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  • pharmacokinetics  (70)
  • temperature  (52)
  • oxidation  (49)
  • Springer  (171)
  • American Meteorological Society
  • Institute of Physics
  • 1995-1999  (171)
  • 1990-1994
  • 1940-1944
  • 1996  (171)
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  • Springer  (171)
  • American Meteorological Society
  • Institute of Physics
  • Wiley-Blackwell  (12)
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  • 1995-1999  (171)
  • 1990-1994
  • 1940-1944
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  • 1
    Electronic Resource
    Electronic Resource
    Non-reciprocal cross-incompatibility in Trichogramma deion (1996)
    Springer
    Entomologia experimentalis et applicata 80 (1996), S. 481-489 
    Details
    ISSN: 1570-7458
    Keywords: reproductive compatibility ; hybrid inviability ; temperature ; Trichogramma ; biological control ; Hymenoptera ; Trichogrammatidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In non-reciprocal cross-incompatibility (NRCI), the crossing of a female of a strain A with a male of a strain B results in hybrid offspring, whereas the reciprocal cross produces few or no hybrids. Only females are of hybrid origin in Hymenoptera because they arise from fertilized eggs; males arise from unfertilized (haploid) eggs. Crosses between many strains of Trichogramma deion showed some degree of NRCI. Crosses between a T. deion culture collected in Seven Pines, California (SVP) with one from Marysville, California (MRY) showed an extreme form of NRCI in which practically no female offspring was produced when MRY females were crossed with SVP males. The reciprocal cross produced a close to normal proportion of female and male offspring. Detailed studied of this cross indicated that 1) the female offspring produced in the compatible interstrain cross were not the result of parthenogenesis but were true hybrids, 2) the incompatible interstrain cross did not produce female offspring because fertilized eggs died during development, 3) the death of these eggs could not be prevented by either antibiotic or temperature treatment, 4) cytoplasmically inherited factors causing NRCI could be discounted because backcrossed females with the genome of MRY and the cytoplasm of SVP, exhibit the NRCI relationship characteristic of their genome. Therefore the NRCI between these strains appears to be caused by a modification coded for by the nuclear genes of MRY that results in incompatibility when SVP sperm fertilizes MRY eggs. In addition the level of incompatibility in crosses between the SVP females and MRY males is temperature sensitive, the higher the rearing temperature the lower the level of compatibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343472
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  • 2
    Electronic Resource
    Electronic Resource
    Survival of Bemisia tabaci adults under different climatic conditions (1996)
    Springer
    Entomologia experimentalis et applicata 80 (1996), S. 511-519 
    Details
    ISSN: 1570-7458
    Keywords: sweet potato whitefly ; temperature ; relative humidity ; migration and dispersal ; virus transmission ; Homoptera ; Aleyrodidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ability of the sweet potato whitefly, Bemisia tabaci Gennad., to survive a range of environmental conditions was investigated in the laboratory. The range of temperature and humidity investigated corresponds to the normal climatic range during B. tabaci's summer migration in Israel. Adult whiteflies confined to small test cages were exposed to combinations of temperature (25, 30, 35, and 41 °C) and relative humidity (20, 50, 80, and 100%) for periods of 2, 4, or 6 h. A logistic regression model describing the four-dimensional surface defining percent survival as a function of time, temperature, and humidity was developed. Using stepwise regression to exclude non-significant terms, the linear predictor included temperature, and the products of temperature and time, and humidity and time. The model accounted for 75% of the variance. A reparameterization of the fitted regression model suggests that survival potential is conditioned by temperature conditions prevailing during the previous 10 h. Whitefly survival after 2 h exposure ranged from ≈ 90% survival at 20°C and 100% RH, to 〈2% survival at 41°C and 20% r.h.. No whiteflies survived more than 2 h exposure at these latter extremes of temperature and humidity. Survival rates decreased slightly after experimental whiteflies were kept in a cage with food a further 20 h at 25±2°C, 55±5% r.h. Investigations of the effects of hunger and virus infection, showed that both increased mortality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343476
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of temperature and vapor pressure deficit on the rate of predation by the predatory mite, Amblyseius cucumeris, on Frankliniella occidentalis (1996)
    Springer
    Entomologia experimentalis et applicata 78 (1996), S. 31-38 
    Details
    ISSN: 1570-7458
    Keywords: Amblyseius cucumeris ; Frankliniella occidentalis ; rate of predation ; temperature ; vapor pressure deficit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of temperature and vapor pressure deficit (VPD) on the rate of predation by the predatory mite, Amblyseius cucumeris (Oudemans) on Frankliniella occidentalis (Pergande) was determined under controlled laboratory conditions. The survival of first instars of F. occidentalis was initially determined by themselves. Then the number of first instars that were killed by a single female adult of A. cucumeris was determined for the same density of thrips. The differences in the mortality between the two experiments were used to calculate the rate of predation by A. cucumeris under a range of temperature and VPD regimes. Rate of predation was expressed as the number of thrips killed per h to account for the different time periods that the trials lasted. A quadratic model was fitted to the data. At a constant temperature, the rate of predation decreased with increasing VPD for VPDs 〈-1.24 to 1.44 kPa. Above these VPDs, the rate of predation started to increase again. At a constant VPD, the rate of predation decreased slightly at the lower temperatures and increased at the higher temperatures. The rate of change was dependent upon the VPD. By using the quadratic model, the rate of predation can be predicted for the range of hygrothermal conditions that would be encountered in the greenhouse. The optimal condition for maximum rate of predation by A. cucumeris on first instars of F. occidentalis in the greenhouse is a VPD 〈- 0.75 kPa at the recommended production temperatures and VPDs (17 to 25°C and 〈- 1.5 kPa).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304454
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  • 4
    Electronic Resource
    Electronic Resource
    Temperature influence on cohort parameters and demographic characteristics of the two cowpea coreids Clavigralla tomentosicollis and C. shadabi (1996)
    Springer
    Entomologia experimentalis et applicata 78 (1996), S. 201-213 
    Details
    ISSN: 1570-7458
    Keywords: cowpea ; Vigna unguiculata ; pod sucking bugs ; age-specific life tables ; temperature ; insect development ; cohort statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Age-specific life tables of two important pests of cowpea, Vigna unguiculata (L.) Walp., the pod sucking bugs Clavigralla tomentosicollis Stål and C. shadabi Dolling (Heteroptera: Coreidae), were obtained from observations carried out at different temperatures. A biophysical model was found satisfactory to describe the temperature-response of developmental and mortality rates of egg and nymphal stages, with a peak developmental rate around 34°C in both species. The variability in development times was small and the experimental data did not permit any conclusion with regard to the Erlang probability density function. Survival of eggs and nymphs remained high between 20° and 30°C for both species. At temperatures above 34°C, C. tomentosicollis survivorship and fecundity was higher than that of C. shadabi, which in turn laid more eggs at temperatures between 20° and 30°C. Maximum fecundity is estimated to be at 29°C for C. tomentosicollis (99 eggs/female) and 26°C for C. shadabi (261 eggs/female). At 30°C, the intrinsic rate of increase reached a maximum in both species, 0.152 per day for C. tomentosicollis and 0.145 per day for C. shadabi, and remained high for C. tomentosicollis until 36°C. C. tomentosicollis performed significantly better on pigeonpea, Cajanus cajan Millsp., than on cowpea at higher temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187518
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  • 5
    Electronic Resource
    Electronic Resource
    Spring behavioral patterns of the apple blossom weevil (1996)
    Springer
    Entomologia experimentalis et applicata 79 (1996), S. 9-17 
    Details
    ISSN: 1570-7458
    Keywords: Anthonomus pomorum ; temperature ; diel cycle ; Coleoptera ; Curculionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Individual pairs of overwintered adult apple blossom weevils, Anthonomus pomorum (L.), confined with apple twigs under different ambient temperatures in the laboratory and on apple trees in the field, were observed through day and night for their spring activities. Flight behavior in relation to ambient temperature was also investigated under laboratory conditions using flight stands. Both sexes displayed predominantly nocturnal behavior patterns in both the laboratory and the field. Feeding, crawling, and mating activities increased following sunset in the field or onset of scotophase in the laboratory while resting occurred most frequently during daylight hours. Results of the laboratory experiments showed that temperature affected significantly the activity patterns. The diel pattern of activities became less distinctive at higher temperatures (above 15°C), and total activities in crawling, feeding, and mating were suppressed significantly at lower temperatures (below 5°C). Over 97% of the test weevils initiated take-off response from flight stands at 20°C within the 30 min trial period; however, flight initiation rarely occurred at temperatures 12°C or below. Overall, results of the laboratory and field experiments indicate that A. pomorum is a remarkably cold-adapted insect with ability to crawl, feed, and mate at a few degrees above freezing, a physiological attribute necessary for the exploitation of early stages of apple bud development in the cold early spring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333816
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of environmental conditions and parasitoid quality on field performance of Trichogramma minutum (1996)
    Springer
    Entomologia experimentalis et applicata 80 (1996), S. 461-468 
    Details
    ISSN: 1570-7458
    Keywords: Trichogramma minutum ; Choristoneura fumiferana ; Ephestia kuehniella ; biological control ; inundative release ; weather ; host acceptance ; realized fecundity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of weather conditions and two parasitoid quality attributes, realized fecundity and host acceptance, were assessed on the field efficacy of mass-released Trichogramma minutum. Temperature was the most important single variable, explaining up to 75% of the variation in field parasitism. There were significant positive relationships between both the sum of the maximum temperatures and the number of degree-hours above a 15 °C threshold, accumulated in the three days following the release, and parasitism in the field. There was a significant negative relationship between the mean relative humidity and the odds of parasitism in the field. Quality parameters based on parasitoid biology were not effective for predicting field efficacy if poor weather conditions persisted after a release. If weather conditions were ‘good’ (i.e. accumulated maximum temperatures above 62 °C, in the 3 days following the release), then parameters such as release rate and fecundity in the lab were useful predictors of field performance. There was no relationship between host acceptance measured in the lab and field parasitism. Given the importance of field temperatures for field performance, selection for cold tolerance of T. minutum would be desirable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343469
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  • 7
    Electronic Resource
    Electronic Resource
    Low ambient temperature decreases cadmium accumulation in the liver and kidneys of the bank vole (Clethrionomys glareolus) (1996)
    Springer
    BioMetals 9 (1996), S. 363-369 
    Details
    ISSN: 1572-8773
    Keywords: cadmium ; copper ; iron ; photoperiod ; temperature ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The importance of photoperiod and ambient temperature on the accumulation of cadmium in the liver and kidneys of bank voles was determined in the present study. Males and females, aged 1 month, were given 3.0 μg Cd ml−1 drinking water and divided into four groups according to photoperiod (16 h light/8 h dark and 8 h light/16 h dark) and ambient temperature (20 or 5°C); liver and kidneys were removed for cadmium as well as copper, iron and zinc analyses at the end of 6 weeks. Bank voles exposed to 5°C in both photoperiods consumed approximately 30% less water containing cadmium than those kept at 20°C. However, the total accumulation of cadmium in the liver and kidneys of males and females exposed to the low temperatures was 4.3–4.8 and 2.2–3.3 times less than that in animals maintained at room temperature in the long and short photoperiod, respectively. Simultaneously, the low temperature brought about an increase in the copper concentrations in the liver (12–43%) and kidneys (47–78%), giving rise to an inverse correlation between the cadmium accumulation and the tissue copper concentration. In contrast to cadmium and copper, the concentrations of iron and zinc were affected primarily by photoperiod. These findings indicate that ambient temperature is an important determinant of cadmium retention in the bank vole. It appears that low temperature decreases tissue cadmium accumulation not only by reducing cadmium intake but also through changes in copper metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00140605
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  • 8
    Electronic Resource
    Electronic Resource
    Selective oxidation of secondary amines over titanium silicalite molecular sieves, TS-1 and TS-2 (1996)
    Springer
    Catalysis letters 37 (1996), S. 213-216 
    Details
    ISSN: 1572-879X
    Keywords: titanium silicalites ; oxidation ; amines ; hydrogen peroxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Titanium silicalite molecular sieves, TS-1 and TS-2 having MFI and MEL structures, respectively, catalyze the oxidation of secondary amines to the corresponding hydroxylamines using hydrogen peroxide as the oxidant. Higher concentrations of H2O2 lead to further oxidation of hydroxylamine to nitrone. Diffuse reflectance spectroscopy shows the formation of a titanium peroxo complex upon addition of hydrogen peroxide to the TS-1 catalyst. The titanium peroxo complex oxidizes the substrate and reforms to a titanyl group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807756
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  • 9
    Electronic Resource
    Electronic Resource
    Catalytic oxidation of cyclohexene with molecular oxygen by polyoxometalate-intercalated hydrotalcites (1996)
    Springer
    Catalysis letters 40 (1996), S. 43-45 
    Details
    ISSN: 1572-879X
    Keywords: oxidation ; cyclohexene ; polyoxometalate-intercalated hydrotalcite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cyclohexene was oxidized with molecular oxygen over transition-metal-substituted polyoxometalate-intercalated hydrotalcites to produce 2-cyclohexene-1-one and 2-cyclohexene-1-ol with high selectivity under mild reaction conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807455
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  • 10
    Electronic Resource
    Electronic Resource
    A broad spectrum catalytic system for removal of toxic organics from water by deep oxidation using dioxygen as the oxidant (1996)
    Springer
    Catalysis letters 40 (1996), S. 95-99 
    Details
    ISSN: 1572-879X
    Keywords: palladium metal ; oxidation ; toxic organics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In water, metallic palladium was found to catalyze the deep oxidation of a wide variety of functional organics by dioxygen at 80–90°C in the presence of carbon monoxide. Several classes of organic compounds were examined: benzene, phenol and substituted phenols, aliphatic and aromatic halogenated compounds, organophosphorus, and organosulfur compounds. In every case, deep oxidation to carbon monoxide, carbon dioxide, and water occurred in high yields, resulting in up to several hundred turnovers over a 24 h period. Since the heterogeneous catalyst can be removed by simple filtration, simultaneous water purification and contaminant destruction becomes feasible. For those substrates that are insoluble in pure water, a mixture of water and perfluorobutyric acid was successfully employed as the solvent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807463
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  • 11
    Electronic Resource
    Electronic Resource
    Ion association of dilute aqueous sodium hydroxide solutions to 600°C and 300 MPa by conductance measurements (1996)
    Springer
    Journal of solution chemistry 25 (1996), S. 711-729 
    Details
    ISSN: 1572-8927
    Keywords: Conductivity ; aqueous ; sodium hydroxide ; ion association ; temperature ; pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The limiting molar conductances Λ0 and ion association constants of dilute aqueous NaOH solutions (〈0.01 mol-kg−1) were determined by electrical conductance measurements at temperatures from 100 to 600°C and pressures up to 300 MPa. The limiting molar conductances of NaOH(aq) were found to increase with increasing temperature up to 300°C and with decreasing water density ρw. At temperatures ≥400°C, and densities between 0.6 to 0.8 g-cm−3, Λ0 is nearly temperature-independent but increases linearly with decreasing density, and then decreases at densities 〈0.6 g-cm−3. This phenomenon is largely due to the breakdown of the hydrogen-bonded, structure of water. The molal association constants K Am for NaOH( aq ) increase with increasing temperature and decreasing density. The logarithm of the molal association constant can be represented as a function of temperature (Kelvin) and the logarithm of the density of water by $$\begin{gathered} log K_{Am} = 2.477 - 951.53/T - (9.307 \hfill \\ - 3482.8/T)log \rho _{w } (25 - 600^\circ C) \hfill \\ \end{gathered} $$ which includes selected data taken from the literature, or by $$\begin{gathered} log K_{Am} = 1.648 - 370.31/T - (13.215 \hfill \\ - 6300.5/T)log \rho _{w } (400 - 600^\circ C) \hfill \\ \end{gathered} $$ which is based solely on results from the present study over this temperature range (and to 300 MPa) where the measurements are most precise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973780
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  • 12
    Electronic Resource
    Electronic Resource
    Oxidative dehydrogenation of ethane over La1−xSrxFeO3−δ perovskite oxides (1996)
    Springer
    Catalysis letters 38 (1996), S. 189-195 
    Details
    ISSN: 1572-879X
    Keywords: perovskite ; La1−xSrxFeO3−δ ; dehydrogenation ; oxidation ; ethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Catalysts of the composition La1−xSrxFeO3−δ, 0⩽x ⩽1, have been tested for the oxidative dehydrogenation of ethane in the temperature range 300–800°C. The catalyst is active above 400°C, giving a maximum yield of 37% ethylene at 650°C. Above 650°C, synthesis gas was formed together with methane, suggesting that the reforming reaction and thermal cracking of ethane took place. The catalytic data are compared to conductivity measurements on the same material, and a good correlation between the activity and p-type conductivity has been found. In the phase diagram for the system LaFeO3-SrFeO3−δ, a phase separation to two types of (La, Sr)FeO3−δ perovskites was observed in the La/Sr binary composition in the temperature range below 800°C. The phase separation can elucidate the dependency of the catalytic activity on its p-type conductivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806567
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  • 13
    Electronic Resource
    Electronic Resource
    Inhibition of CO oxidation on hydroxyapatite by tetrachloromethane (1996)
    Springer
    Catalysis letters 39 (1996), S. 205-208 
    Details
    ISSN: 1572-879X
    Keywords: oxidation ; hydroxyapatite ; carbon monoxide ; inhibition ; tetrachloromethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The introduction of tetrachloromethane (TCM) into the feedstream of CO and O2 inhibits the formation of CO2 on hydroxyapatite. TCM interacts with the surface of hydroxyapatite to form its chlorinated analogue, chlorapatite, which suppresses the oxidation of CO to CO2. Thus, in the oxidative coupling of methane the beneficial effects of the addition of TCM to the feedstream result, at least in part, from the suppression of the further oxidation of CO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805584
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  • 14
    Electronic Resource
    Electronic Resource
    Oxidation of methanol at copper surfaces (1996)
    Springer
    Catalysis letters 37 (1996), S. 79-87 
    Details
    ISSN: 1572-879X
    Keywords: methanol ; oxidation ; copper ; electron spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The role of preadsorbed oxygen present at Cu(111), Cu(110) and polycrystalline surfaces in the oxidation of methanol has been investigated by X-ray and electron energy loss spectroscopies. In addition to the well established formation of methoxy species and its subsequent decomposition and desorption as formaldehyde, a second reaction pathway to surface formate is present. The latter is temperature dependent being undetectable at 260 K at a polycrystalline surface but occurs at a significant rate at 295 K and above. The limitations of experimental data for methanol oxidation by temperature programmed desorption and molecular beam techniques are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00813523
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  • 15
    Electronic Resource
    Electronic Resource
    Synergistic effects during CO oxidation over mixed oxides. Study of (Fe2O3+SnO2) and (Mn2O3+SnO2) systems (1996)
    Springer
    Catalysis letters 37 (1996), S. 181-185 
    Details
    ISSN: 1572-879X
    Keywords: synergistic effect ; carbon monoxide ; oxidation ; mixed oxides ; iron oxide ; tin oxide ; manganese oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Based on the comparative evaluation of the catalytic activity of Fe2O3, Mn2O3 and SnO2 and their mixed oxides (Fe2O3+SnO2) and (Mn2O3+SnO2), it is shown that the system (Mn2O3+SnO2) shows strong synergistic effects during CO oxidation reaction. Such effects are not observed for the analogous system (Fe2O3+SnO2). Based on the calcination and reduction behaviour of these two mixed oxide systems and the redox potentials of the involved cations, the possible reasons for the observance of synergistic effects for the (Mn2O3+SnO2) system are discussed.
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    URL: http://dx.doi.org/10.1007/BF00807751
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  • 16
    Electronic Resource
    Electronic Resource
    Non-uniform surface kinetics with two types of sites: the case of ethanol oxidation on molybdenum oxide (1996)
    Springer
    Catalysis letters 39 (1996), S. 67-71 
    Details
    ISSN: 1572-879X
    Keywords: non-uniform surface ; kinetics ; ethanol ; oxidation ; molybdenum oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Temkin's theory of rates of catalytic reactions on non-uniform surfaces is extended to the MoO3-catalyzed oxidation of ethanol to acetaldehyde. Two types of sites are assumed to be present, an oxygen atom site that can be modeled with uniform properties and a metal atom site characterized by non-uniform properties both for ethanol chemisorption to an ethoxide intermediate and the conversion of this intermediate to acetaldehyde. The rate-limiting step is the cleavage of a C-H bond in the absorbed ethoxide intermediate. Non-uniform surface kinetics leads to a kinetic rate expression of the form $$v = kP_{C_2 H_5 OH}^{1 - m} P_{O_2 }^{(1 - m)/4} P_{H_2 O}^{ - (1 - m)/2} $$ . Such a rate expression, withm=0.14, is shown to provide a good fit to kinetic data for the selective oxidation of ethanol on a silica supported molybdenum oxide catalyst.
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    URL: http://dx.doi.org/10.1007/BF00813732
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  • 17
    Electronic Resource
    Electronic Resource
    Baeyer-Villiger rearrangement catalysed by titanium silicate molecular sieve (TS-1)/H2O2 system (1996)
    Springer
    Catalysis letters 40 (1996), S. 47-50 
    Details
    ISSN: 1572-879X
    Keywords: Baeyer-Villiger ; titanium silicate molecular sieve ; oxidation ; rearrangement ; titanium peroxo ; triphase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Titanium silicate molecular sieve TS-1 has been found to be an efficient catalyst for Baeyer-Villiger (BV) oxidation of cyclic and aromatic ketones under triphase conditions (solid catalyst along with two immiscible liquid reactants in the absence of any cosolvent), using dilute H2O2. Reactions studied are the oxidation of cyclohexanone and acetophenone. Whereas in the case of cyclohexane,ε-caprolactone, a BV product along with hydroxy and diketones is formed, in the case of acetophenone, phenyl acetate, a BV product along witho- andp-hydroxyacetophenone is formed. The acidic nature of titanium peroxo species, stabilised by water, is proposed to be responsible for such reactions under triphasic reaction conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807456
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  • 18
    Electronic Resource
    Electronic Resource
    Platinum particle size effect on the oxidative dehydrogenation of aqueous ethanol (1996)
    Springer
    Catalysis letters 36 (1996), S. 31-36 
    Details
    ISSN: 1572-879X
    Keywords: ethanol ; kinetics ; oxidation ; oxydehydrogenation ; platinum ; structure sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the platinum particle size was investigated for the catalytic oxidative dehydrogenation of aqueous ethanol to ethanal at a temperature of 303 K, an ethanol concentration of 260 mol m−3, a partial oxygen pressure 60 kPa, a pH of 9, and an ethanal and ethanoate concentration of 20 mol m−3. A particle size effect on the turnover frequency was observed but only for particle sizes smaller than 2 nm. Hence, the reaction shows a limited structure sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807202
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  • 19
    Electronic Resource
    Electronic Resource
    Perfluoroalkylporphyrin complexes as active catalysts for the reaction of isobutane with oxygen and the decomposition of tert-butyl hydroperoxide (1996)
    Springer
    Catalysis letters 36 (1996), S. 69-73 
    Details
    ISSN: 1572-879X
    Keywords: oxidation ; metalloporphyrins ; hydroperoxide decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new family of metalloporphyrin complexes having perfluoroalkyl groups in the meso-positions of the ring are active catalysts for the oxidation of isobutane to tert-butyl alcohol, TBA, and for the decomposition of tert-butyl hydroperoxide to TBA. This discovery extends the limited number of meso-substituents that can be used to enhance catalytic activity and fits the postulate that groups that withdraw electrons from the porphyrin periphery give rise to active catalysts for alkane oxidation. The perfluoroalkyl groups also confer oxidative stability, hydrophobicity and lower cost to the catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807207
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  • 20
    Electronic Resource
    Electronic Resource
    The environmental history of a mountain lake (Lago Paione Superiore, Central Alps, Italy) for the last c. 100 years: a multidisciplinary, palaeolimnological study (1996)
    Springer
    Journal of paleolimnology 15 (1996), S. 245-264 
    Details
    ISSN: 1573-0417
    Keywords: palaeolimnology ; acidification ; diatoms ; chrysophytes ; pigments ; chironomids ; temperature ; Alps ; Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A palaeoecological study of an oligotrophic alpine lake, Paione Superiore (Italy), provided a record of historical changes in water quality. Historical trends in lake acidification were reconstructed by means of calibration and regression equations from diatoms, chrysophycean scales and pigment ratios. The historical pH was inferred by using two different diatom calibration data sets, one specific to the alpine region. These pH trends, together with the record of sedimentary carbonaceous particles and chironomid remains, indicate a recent acidification of this low alkalinity lake. Concentration of total organic matter, organic carbon, nitrogen, biogenic silica (BSiO2), chlorophyll derivatives (CD), fucoxanthin, diatom cell concentration and number of chironomid head capsules increased during the last 2–3 decades. When expressed as accumulation rates, most of these parameters tended to decrease from the past century to c. 1950, then all except P increased to the present day. A marked increase in sedimentary nitrogen may be related to atmospheric pollution and to the general increases in output of N in Europe. High C/N ratios indicate a prevailing allochthonous source of organic matter. Finally, the increase in measured air temperature from the mid-1800's appeared to be related to lake water pH before industrialization: cold periods generally led to lower pH and vice-versa. The more recent phenomenon of anthropogenic acidification has apparently decoupled this climatic-water chemistry relationship.
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    URL: http://dx.doi.org/10.1007/BF00213044
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    Fungi associated with post-harvest rot of black plum (Vitex doniana) in Nigeria (1996)
    Springer
    Mycopathologia 136 (1996), S. 109-114 
    Details
    ISSN: 1573-0832
    Keywords: Fungi ; post-harvest rot ; relative humidity ; temperature ; Vitex doniana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The fungi associated with rot of Vitex doniana fruits (blackplum) were isolated and identified. Aspergillus niger, Botryodiplodia theobromae, Candida spp. Penicillium chrysogenum, Rhizopus stolonifer, Fusarium pallidoroseum F. oxysporum and Mucor mucedo were the primary rot causing fungi in contrast to Cladosporium herbarum and Mucor circinelloides which were just present as secondary colonizers. The rot fungi penetrated mainly through wounds and bruises on the surface of fruits. Mature green fruits were less susceptible to infection than half ripe and fully ripened red fruits. Optimum rot by pathogenic isolates occurred at 25–30 °C and relative humidity 72.5–100%. The results of investigation of influence of storage temperatures and relative humidity on the quality of uninoculated healthy fruits are presented and discussed.
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    URL: http://dx.doi.org/10.1007/BF00437504
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    Phosphorus supplying capacity of heavily fertilized soils II. Dry matter yield of successive crops and phosphorus uptake at different temperatures (1996)
    Springer
    Nutrient cycling in agroecosystems 47 (1996), S. 123-134 
    Details
    ISSN: 1573-0867
    Keywords: heavily fertilized soils ; P supplying capacity ; P uptake ; residual P ; soil test methods ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nine heavily fertilized soils were collected from southern and central Norway. A greenhouse experiment in the phytotron was conducted to evaluate the P supplying capacities of these soils at different temperatures (9, 12 and 18 °C). The crops were grown in succession and the sequence was oat, rye grass (cut twice), oat, rape and oat. Effect of temperature on dry matter (DM) yield and P uptake was more marked up to the fourth crop but the effect varied among crops. The DM yields of oat and rape increased with increasing temperature but the opposite was the case with rye grass. The yield differences among soils at 12 °C were highly significant (p 〈 0.01) in contrast to 9 and 18 °C. The amount of P taken up by plants in these soils was highest at 18. °C. The P supplying capacity was highest in the soils with higher content of organic P. Generally, the soils of very fine and coarse texture classes failed to supply enough P to crops to avoid P deficiency in the successive crops. Soil P test (P-NH4-lactate) values in most of the soils increased with increasing temperatures. The highest temperature effect was seen in the Særheim sand soil. Soil P test extractants P-AL, Bray-1 and Colwell-P were used to determine P in the soil after each harvest and the soil P test values were compared with P uptake by crops. Only the P-AL extractant was significantly correlated to cumulative P removal (CPR) by plants in most of the soils. Regression equation was calculated for each soil. The value of removed P per harvest (RPH) varied from 10.33 to 20.87 mg P kg−1 soil. Phosphorus drawdown slope was determined for each soil and the number of consecutive harvests necessary to reduce the P-AL value to a normal level (110 mg P kg−1 soil) was calculated. The drawdown slope varied widely (1.257–2.801) and this reflected the P buffer capacity and the number of crops required to lower the soil test P value to a normal level. The highest drawdown slope was found in the soils with higher P supplying capacities. The Bray-1 extractant was significantly correlated in the soils with higher buffer capacity but the Colwell-P method did not show significant correlation in any of the soils.
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    URL: http://dx.doi.org/10.1007/BF01991544
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    Effects of temperature on nutrient release from slow-release fertilizers (1996)
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 179-187 
    Details
    ISSN: 1573-0867
    Keywords: electrical conductivity ; leaching ; nitrogen ; pH ; phosphorus ; potassium ; release pattern ; slow-release fertilizers ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effect of temperature on the release of N, P, and K from slow-release fertilizers (SRF). The study was conducted in micro-lysimeters filled with moist peat medium. Increasing the temperature from 4 to 12°C slightly increased N release from three different slow-release N (SRN) carriers with different particle sizes and coating thicknesses. At 21°C the rate of release was significantly different than the other two temperatures. Urea formaldehyde (UF), sulphur coated urea (SCU) and coated calcium nitrate (CCN), incubated in sphagnum moss peat, released between 3 and 20% of the applied N in six weeks. For eight synthetic and organic NPK carriers, the release pattern was similar to UF and SCU. However, the leaching losses of N from the NPK fertilizers were up to twenty times more than for the SRN products. Except for Osmocote® and Duna, which released 30–40% of the applied N as mineral-N within six weeks, all other slow-release and slowly mineralized NPK carriers acted like readily water-soluble compound NPK. Temperature did not affect the nutrient release from NPK fertilizers.
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    URL: http://dx.doi.org/10.1007/BF00420552
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    Effects of temperature and solar radiation interactions on the survival of quiescent conidia of the entomopathogenic hyphomycetePaecilomyces fumosoroseus (Wize) Brown and Smith (1996)
    Springer
    Mycopathologia 135 (1996), S. 163-170 
    Details
    ISSN: 1573-0832
    Keywords: Entomopathogenic hyphomycete ; Paecilomyces fumosoroseus ; inoculum persistence ; solar radiation ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The detrimental effect of solar radiation on the survival of conidia of the entomopathogenic fungusPaecilomyces fumoroseus was studied by monitoring germinability and ability to form colonies (CFU) of conidia irradiated at two temperatures, 25 and 35 °C, harmless to shaded conidia. There was no apparent effect when spores were exposed to a high level of artificial radiation (0.66 W m−2 UVB). However, at a lower level of irradiance (0.33 W m−2), effects of radiation occurred more quickly at 35 °C than at 25 °C. Under natural solar radiation, the rate of decrease in germinability or viability was doubled at 35 °C as compared to 25 °C, indicating an interaction between temperature and radiation effects under natural conditions. This interaction was not detected in indoor experiments, indicating that the spectral distribution of UV radiation has to be taken in account as well as its irradiance when studying its effects.
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    URL: http://dx.doi.org/10.1007/BF00632338
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    The dependence of transport properties ofin situ rocks on pore fluid composition and temperature (1996)
    Springer
    Surveys in geophysics 17 (1996), S. 289-306 
    Details
    ISSN: 1573-0956
    Keywords: Effective properties ; pore fluids ; cracked rock ; permeability ; stress ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Fluids saturating cracked rocks within the crust can vary widely in composition and physical properties, which depend greatly on pressure and temperature. External non-hydrostatic stress applied to a cracked medium may result in a significant change of crack volume (and hence, for the undrained regime, pore-fluid pressure) due to the processes of crack closure (opening), and thus lead to a drastic change of the overall physical parameters of a rock. The purpose of the study is to estimate theoretically, using the effective-medium theory, the macroscopic seismic and transport parameters (such as permeability) of cracked rocks (granites) saturated with hydrocarbon gases, oils, brines and water. Variations of crack geometry and fluid parameters in the closed system (at constant fluid mass) under uniaxial compression are considered as well. The results show that composition of a saturating fluid as well as fluid temperature greatly influence the effective permeability and shear velocities of a rock mass, while thermal conductivity is not so sensitive to variations of fluid parameters.
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    URL: http://dx.doi.org/10.1007/BF01904045
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    Powdered elemental sulphur: oxidation rate, temperature dependence and modelling (1996)
    Springer
    Nutrient cycling in agroecosystems 47 (1996), S. 19-28 
    Details
    ISSN: 1573-0867
    Keywords: elemental sulphur ; model ; oxidation rate ; particle size distribution ; soil ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Finely-powdered elemental sulphur is a useful source of fertilizer S, being readily oxidizable in soil to plant-available sulphate yet possessing some slow release characteristics. Two mesh sizes were evaluated using four soils from northeast Scotland. Particle size analysis found that the 120 and 300 mesh S samples had specific surface areas of 1300 and 1940 cm2 g−1, respectively, with most of the surface area in particles of 10 – 20 µm diameter. The S oxidation rate was similar in all four soils but was greater for the 300 mesh than for the 120 mesh S: mean values of 51% and 18% were oxidized over 7 weeks at 14 °C, respectively. The time course of oxidation followed a sigmoidal pattern with a pronounced lag which was modelled using the logistic equation. Maximum specific oxidation rates were 11–28 µg S cm−2 day−2 for the 300 mesh S at 14 °C. These were significantly slower at 7 °C and the temperature response was calculated as a Q10 of 4.0. A model of seasonal S oxidation was developed using a cosine function for the annual temperature, the Arrhenius equation to relate S oxidation rate to temperature and a generalization of the logistic equation to describe the time course of S oxidation. Simulations showed that the 300 mesh S would be useful for spring S applications in east Scotland and if applied in autumn could supply S during the autumn and again in the spring. The 120 mesh S would be less effective in autumn but more resistant to winter leaching. The 120 mesh S applied to the warmer soils of southwest England would behave the same as 300 mesh S applied in east Scotland.
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    URL: http://dx.doi.org/10.1007/BF01985715
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    Effect of temperature on polaronic and bipolaronic structures of the adiabatic Holstein model (1996)
    Springer
    Journal of statistical physics 85 (1996), S. 471-488 
    Details
    ISSN: 1572-9613
    Keywords: Electron-phonon interaction ; temperature ; polaron ; Holstein model ; bifurcation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is proved that the polaronic and bipolaronic structures found in the adiabatic Holstein model at large electron-phonon coupling by Aubry, Abramovici, and Raimbault survive under connection of the electrons to a low-temperature heat bath, uniformly in the size of the system. Bounds are computed for one-dimensional nearest neighbor chains, and some sample solutions are continued numerically.
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    URL: http://dx.doi.org/10.1007/BF02174215
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    Influence of age, frailty and liver function on the pharmacokinetics of brofaromine (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 387-391 
    Details
    ISSN: 1432-1041
    Keywords: Key words Liver function tests; elderly ; pharmacokinetics ; geriatrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The pharmacokinetics of brofaromine, a selective inhibitor of monoamine oxidase A, was evaluated in 12 frail elderly patients (66–92 y) and 12 healthy volunteers (20–35 y). Methods: Quantitative liver function tests were performed to show whether brofaromine elimination in the elderly could be predicted from noninvasive assessment of CYP1A2 activity (caffeine clearance) or liver plasma flow (sorbitol clearance). Results: In the elderly the AUC of brofaromine was significantly increased (e.g. for the 75 mg dose 43.2 vs 19.9 μmol*h⋅l−1, clearance was reduced (5.0 vs. 11.8 l⋅h−1), the volume of distribution was smaller (130 vs. 230 l), and the half-life was slightly increased (19.0 vs. 14.2 h). No significant correlation was observed between hepatic plasma flow and brofaromine clearance (r = 0.41, P = 0.05), whereas CYP1A2 activity and brofaromine clearance were tightly correlated (r = 0.94, P 〈 0.0001). Conclusion: Caffeine clearance, a simple, noninvasive test of CYP1A2 activity, is predictive of brofaromine clearance.
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    URL: http://dx.doi.org/10.1007/s002280050037
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    Design of a suitable formulation of FK613, a novel antiallergic agent, based on its pharmacokinetic and pharmacodynamic properties in healthy subjects (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 279-284 
    Details
    ISSN: 1432-1041
    Keywords: Antiallergic drug ; FK613 ; pharmacokinetics ; histamine skin-test ; drug formulation ; urinary excretion ; safety
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The pharmacokinetic and pharmacodynamic properties of FK613, a novel indolyl piperidine derivative, were investigated after oral administrations of 5, 10 and 20 mg in hard gelatin capsules to healthy male volunteers. FK613 was rapidly and almost completely absorbed, and 〉89% was recovered in the urine as the unchanged form. The urinary excretion of FK613 was linearly correlated with plasma concentration and its low water solubility was the main concern regarding the safety. In another experiment using a double-blind crossover design, in which 0 (placebo), 5 and 20 mg FK613 were administered to determine the plasma concentration-effect relationship, suppression of the intradermal histamine-induced skin reaction by FK613 was observed. Thus, the maintenance of a plasma concentration of FK613 in the range of 80–250 ng · ml-1 was recommended to ensure the suppression of histamine-induced wheal by 〉50% and not to exceed the solubility in urine. To achieve this, a new hydrogel-type formulation of FK613 was developed, with the aim both of delaying its absorption, so as to suppress the sharp rise in plasma concentration, and of maintaining the effective concentration for a longer period of time. This formulation was administered after meals at the doses of 20, 30, 40, 50 and 60 mg, and at repeated doses of 40 mg twice daily for 6.5 days to evaluate the pharmacokinetics and safety in healthy subjects. The area under the plasma concentration curve increased linearly with dose, whereas maximum plasma concentration (Cmax) tended to peak as dose increased, indicating the desirable properties of this formulation. Although Cmax exceeded 250 ng/ml at doses of 30 mg or more, no urinary crystal formation was observed on careful inspection of urine.
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    URL: http://dx.doi.org/10.1007/BF00226328
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    Multiple dose pharmacokinetics of tiludronate in healthy volunteers (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 175-181 
    Details
    ISSN: 1432-1041
    Keywords: Key words Tiludronate; healthy volunteers ; bisphosphonates ; pharmacokinetics ; calcium metabolism ; bone resorption ; adverse events
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objectives: A double-blind, placebo-controlled study was conducted to assess the pharmacokinetics and pharmacodynamics of the bisphosphonate tiludronic acid, administered once daily as sodium tiludronate 200, 400, 600 and 800 mg for 12 days. Four groups of ten subjects participated in the study, with a drug to placebo ratio of 4:1. Methods: Pre-dose blood samples were taken on alternate days, starting on Day 1 and additional samples were collected over 144 h following the final dose on Day 12. Urine was collected over 24 h after the final dose. Indices of calcium homeostasis and biochemical markers of bone turnover were assessed during the study as pharmacodynamic parameters. Tolerability was evaluated with special emphasis on renal function and gastrointestinal irritation. Adverse experiences were assessed at regular time intervals. Results and conclusions: Steady state was attained from Day 4 (200 mg) or from Day 6 (400, 600 and 800 mg). Following the final dose on Day 12, minimal plasma concentrations (Cmin) ranged between 0.19 and 1.5 mg ⋅ l−1, and maximal plasma concentrations (Cmax) between 1.1 and 7.8 mg⋅l−1 for the lowest and highest doses, respectively. A supra-proportional increase in Cmax, AUC24 and Ae 24 with dose was observed. There was a linear relationship between the plasma tiludronic acid and its urinary excretion rate, so, the disproportional rise in Cmax and AUC24 with increasing dose could not be attributed to saturation of renal excretion. Certain indices of calcium homeostasis changed significantly during the study, but generally, became only prominent at the highest dose level of 800 mg. Total serum calcium and the urinary calcium/creatinine clearance ratio fell, indicating depression of osteoclastic bone resorption, which was not revealed by serum osteocalcin levels probably because of the brevity of the treatment (12 days). In response to the decline in serum calcium, serum 1,25-dihydroxyvitamin D3 and intact PTH (1–84) levels increased. None of the safety parameters raised any concerns about the safety of sodium tiludronate administered in this way.
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    Effect of grapefruit juice on the pharmacokinetics of amlodipine in healthy volunteers (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 189-193 
    Details
    ISSN: 1432-1041
    Keywords: Key words Dihydropyridine ; Amlodipine ; Grapefruit juice; flavonoids ; interaction ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract. Objective: This study was performed to assess whether coadminstration with grapefruit juice significantly affects the pharmacokinetics of amlodipine, a dihydropyridine class calcium antagonist with slow absorption, distribution and low plasma clearance. The primary objective was to evaluate whether short exposure to grapefruit juice could affect the metabolism of amlodipine to an extent similar to that previously demonstrated for other dihydropyridines (e.g. felodipine, nisoldipine, nitrendipine). Methods: Twelve healthy male volunteers followed a randomised, open crossover study design, comparing the effect of a single oral dose of amlodipine (5 mg) taken together with a glass of grapefruit juice (250 ml) vs water. Blood samples to determine plasma concentration were taken and blood pressure (BP) and heart rate (HR) were measured throughout the study. Results: When amlodipine was coadministered with grapefruit juice, Cmax was 115% and AUC(0–72 h) was 116% compared with water, but tmax was not significantly changed. There were no significant differences in BP and HR between the two treatments. A small decrease in diastolic BP, however, was observed in both treatments 4–8 h after drug administration, coinciding with Cmax, but this was normalised after 12 h. The BP reduction seen was compensated by a slight increase in HR, which remained throughout the study. Conclusion: An interaction between grapefruit juice and amlodipine was demonstrated. The haemodynamic data showed that a dose of 5 mg was sufficient to achieve a BP reduction in healthy subjects, but the increase in amlodipine plasma concentration seen after intake of grapefruit juice was too small to significantly affect BP or HR. The clinical significance of this food/drug interaction, however, cannot be ignored since there is considerable variation between individuals and a more extensive intake of grapefruit juice might give more pronounced effects.
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    Haemodynamic effects and pharmacokinetics of oral d-and l-nebivolol in hypertensive patients (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 259-264 
    Details
    ISSN: 1432-1041
    Keywords: Key words Nebivolol ; Hypertension; d ; l-enantiomers ; pharmacokinetics ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Nebivolol is a selective β1-adrenergic receptor blocker possessing an ancillary vasodilating effect. The objective of the present study was to study the haemodynamic and pharmacokinetic properties of nebivolol 5 mg once daily in a double-blind, placebo-controlled cross-over study. Methods: Fifteen patients, 12 men and 3 women, with essential hypertension were investigated. Blood pressure and peripheral circulation were determined after acute oral nebivolol administration, 5 mg daily, and after 4 weeks treatment. Results: The acute effect on blood pressure upon single-dosing was weak and non-significant. After 4 weeks both systolic blood pressure (152 vs 163 mmHg) and diastolic blood pressure (89 vs 97 mmHg) were significantly reduced after nebivolol treatment as compared to placebo. Following the first dose the venous volume was higher on placebo (5.88 ml ⋅ 100 ml−1 tissue) as compared to active nebivolol treatment (5.17 ml ⋅ 100 ml−1 tissue), while there were no statistically significant differences with regard to venous plethysmographic findings after 1 month on placebo (5.53 ml ⋅ 100 ml−1 tissue) or on active treatment (5.97 ml ⋅ 100 ml−1 tissue). Calculated peripheral resistance did not differ between active treatment (617 units) or placebo (548 units) after the first dose, whereas it was significantly lowered after 4 weeks of nebivolol treatment (483 units) as compared to placebo (593 units). Conclusions: Oral nebivolol 5 mg once daily lowered blood pressure and heart rate during steady state compared to placebo. Moreover, venous volume was reduced during acute but not steady-state dosing, while peripheral resistance was unaffected in the acute phase but reduced during steady state. Plasma concentrations of the separate enantiomers plus hydroxylated metabolites after the first and last dose in hypertensive patients were similar to those in healthy subjects.
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    URL: http://dx.doi.org/10.1007/s002280050194
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    Lack of pharmacodynamic and pharmacokinetic interaction between pantoprazole and phenprocoumon in man (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 277-281 
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    ISSN: 1432-1041
    Keywords: Key words Pantoprazole; Proton pump inhibitor drug interaction ; oral anticoagulant phenprocoumon ; pharmacodynamics ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Pantoprazole is a selective proton pump inhibitor characterized by a low potential to interact with the cytochrome P450 enzymes in man. Due to the clinical importance of an interaction with anticoagulants, this study was carried out to investigate the possible influence of pantoprazole on the pharmacodynamics and pharmacokinetics of phenprocoumon. Methods: Sixteen healthy male subjects were given individually adjusted doses of phenprocoumon to reduce prothrombin time ratio (Quick method) to about 30–40% of normal within the first 5–9 days and to maintain this level. The individual maintenance doses remained unaltered from day 9 on and were administered until day 15. Additionally, on study days 11–15, pantoprazole 40 mg was given per once daily. As a pharmacodynamic parameter, the prothrombin time ratio was determined on days 9 and 10 (reference value) and on days 14 and 15 (test value), and the ratio test/reference was evaluated according to equivalence criteria. Results: The equivalence ratio (test/reference) for prothrombin time ratio was 1.02 (90% confidence interval 0.95–1.09), thus fulfilling predetermined bioequivalence criteria (0.70–1.43). The pharmacokinetic characteristics AUC0–24h and Cmax of S(−)-and R(+)-phenprocoumon were also investigated using equivalence criteria. Equivalence ratios and confidence limits of AUC0–24h and of Cmax of S(−)-phenprocoumon (0.93, 0.87–1.00 for AUC0–24h; 0.95, 0.88–1.03 for Cmax) and of R(+)-phenprocoumon (0.89, 0.82–0.96; 0.9, 0.83–0.98) were within the accepted range of 0.8–1.25. Conclusion: Pantoprazole does not interact with the anticoagulant phenprocoumon on a pharmacodynamic or pharmacokinetic level. Concomitant treatment was well tolerated.
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    Influence of age, frailty and liver function on the pharmacokinetics of brofaromine (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 387-391 
    Details
    ISSN: 1432-1041
    Keywords: Liver function tests ; elderly ; pharmacokinetics ; geriatrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The pharmacokinetics of brofaromine, a selective inhibitor of monoamine oxidase A, was evaluated in 12 frail elderly patients (66–92 y) and 12 healthy volunteers (20–35 y). Methods: Quantitative liver function tests were performed to show whether brofaromine elimination in the elderly could be predicted from noninvasive assessment of CYP1A2 activity (caffeine clearance) or liver plasma flow (sorbitol clearance). Results: In the elderly the AUC of brofaromine was significantly increased (e.g. for the 75 mg dose 43.2 vs 19.9 μmol*h·l−1, clearance was reduced (5.0 vs. 11.8 l·h−1), the volume of distribution was smaller (130 vs. 230 l), and the half-life was slightly increased (19.0 vs. 14.2 h). No significant correlation was observed between hepatic plasma flow and brofaromine clearance (r=0.41, P=0.05), whereas CYP1A2 activity and brofaromine clearance were tightly correlated (r=0.94, P〈0.0001). Conclusion: Caffeine clearance, a simple, noninvasive test of CYP1A2 activity, is predictive of brofaromine clearance.
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    URL: http://dx.doi.org/10.1007/BF00203783
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    Pharmacokinetics of moxisylyte in healthy volunteers after intracavernous injection of increasing doses (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 411-415 
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    ISSN: 1432-1041
    Keywords: Moxisylyte ; pharmacokinetics ; intracavernous administration ; healthy volunteers ; adverse events ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The concentration-time profiles of specific metabolites of moxisylyte, an α-adrenoceptor blocking agent, in the plasma and urine from 18 healthy volunteers were investigated after intracavernous (IC) administrations at three dose levels (10, 20 and 30 mg). Results: Four metabolites, unconjugated desacetyl-moxisylyte (DAM), DAM glucuronide, and DAM and monodesmethylated DAM (MDAM) sulphates were found in plasma and urine. For all metabolites, t1/2 elimination was independent of the administered dose (1.19 h for unconjugated DAM; 1.51 h for DAM glucuronide; 1.51 h for DAM sulphate; and 2.17 h for MDAM sulphate). Cmax and AUC increased in direct proportion to dose, except for the inactive DAM glucuronide. Any the differences detected were small and equivalence of the three doses can be accepted. Conclusion: The pharmacokinetics of moxisylyte in humans following intracavernous administration were linear in the dose range 10 to 30 mg.
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    Rectal pharmacokinetics of budesonide (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 293-298 
    Details
    ISSN: 1432-1041
    Keywords: Key words Budesonide; enema ; pharmacokinetics ; healthy subjects ; hepatic bypass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The pharmacokinetics and systemic availability of budesonide after rectal administration of two single enema doses (2 mg in 100 ml fluid of almost identical composition) were compared in 15 healthy volunteers. In 11 of these subjects, 2 mg oral budesonide in a gelatine capsule was given on a separate occasion. An intravenous administration (0.5 mg) was given as reference. With this design, individual hepatic bypass of the rectally administered budesonide dose could be estimated. The pharmacokinetics of the two enema formulations were similar, although not bioequivalent. Mean systemic availability was 16% (range 4.2–43%) and 15% (3.2–50%) after rectal administration and 6.3% (2.4–10%) after oral administration. The rectal data revealed a small intra- but a substantial inter-subject variability in systemic availability. Cmax was 3.3 nmol ⋅ l−1 (0.95–8.2), 3.0 nmol ⋅ l−1 (0.64–8.9) and 1.3 nmol ⋅ l−1 (0.61–3.0), respectively, for the three formulations. Absorption was rapid and essentially terminated within 3 h after rectal dosing [tmax = 1.3 h for both formulations (range 0.5–2.0)], but was slower after oral dosing [tmax = 2.1 h (1.0–6.0)]. If a complete absorption after oral and rectal dosing is assumed, the fraction of the rectal dose entering the liver at first pass can be calculated to be 88% (55–99%). The higher systemic availability and intersubject variability after rectal dosing does not seem to be caused by differences in first-pass liver metabolism but rather by hepatic bypass of a varying portion of administered drug. This portion seems to be typical for an individual and might be explained by anatomical differences between subjects.
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    Rectal pharmacokinetics of budesonide (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 293-298 
    Details
    ISSN: 1432-1041
    Keywords: Budesonide ; enema ; pharmacokinetics ; healthy subjects ; hepatic bypass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The pharmacokinetics and systemic availability of budesonide after rectal administration of two single enema doses (2 mg in 100 ml fluid of almost identical composition) were compared in 15 healthy volunteers. In 11 of these subjects, 2 mg oral budesonide in a gelatine capsule was given on a separate occasion. An intravenous administration (0.5 mg) was given as reference. With this design, individual hepatic bypass of the rectally administered budesonide dose could be estimated. The pharmacokinetics of the two enema formulations were similar, although not bioequivalent. Mean systemic availability was 16% (range 4.2–43%) and 15% (3.2–50%) after rectal administration and 6.3% (2.4–10%) after oral administration. The rectal data revealed a small intra- but a substantial inter-subject variability in systemic availability. Cmax was 3.3 nmol·l-1 (0.95–8.2), 3.0 nmol·l-1 (0.64–8.9) and 1.3 nmol·l-1 (0.61–3.0), respectively, for the three formulations. Absorption was rapid and essentially terminated within 3 h after rectal dosing [tmax=1.3 h for both formulations (range 0.5–2.0)], but was slower after oral dosing [tmax=2.1 h (1.0–6.0)]. If a complete absorption after oral and rectal dosing is assumed, the fraction of the rectal dose entering the liver at first pass can be calculated to be 88% (55–99%). The higher systemic availability and intersubject variability after rectal dosing does not seem to be caused by differences in first-pass liver metabolism but rather by hepatic bypass of a varying portion of administered drug. This portion seems to be typical for an individual and might be explained by anatomical differences between subjects.
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    Increase in magnesium plasma level after orally administered trimagnesium dicitrate (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 317-323 
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    ISSN: 1432-1041
    Keywords: Magnesium ; Plasma level ; pharmacokinetics ; bioavailability ; circadian fluctuation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Magnesium plasma concentrations were measured in healthy probands before and after administration of trimagnesium dicitrate by the oral and intravenous routes. There was a notable circadian fluctuation of the plasma concentration with a peak in the evening hours. After oral administration of 12 and 24 mmol magnesium, a long-lasting, statistically significant increase in plasma magnesium concentration measured as the increase in area under the curve (AUC) between 0 and 12 h, of 3.1% and 4.6%, respectively, was found. After intravenous administration of 4 and 8 mmol magnesium, AUCs increased by 9.5% and 16.1%, respectively. The decline in the plasma magnesium concentration after i.v. administration was compatible with a three-compartment model with a terminal half-time of about 8 h. Although no absolute value of the oral bioavailability of trimagnesium dicitrate could be determined from the data, our results may be important in helping to elucidate the influence of magnesium preparations on the plasma magnesium concentration. By comparing the effects of different preparations, it should be possible to estimate the relative oral bioavailability and the bioequivalence of these preparations.
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    URL: http://dx.doi.org/10.1007/BF00226334
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    Multiple-dose clinical pharmacology of the catechol-O-methyl-transferase inhibitor tolcapone in elderly subjects (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 47-55 
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    ISSN: 1432-1041
    Keywords: Key words Tolcapone ; Elderly; levodopa ; pharmacokinetics ; pharmacodynamics ; multiple-dose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract. Objective: The purpose of this study was to assess the multiple-dose clinical pharmacology of tolcapone, a novel catechol-O-methyltransferase (COMT) inhibitor, in elderly subjects. Methods: The drug was administered orally t.i.d. for 7 days to four sequential groups of eight elderly subjects (gender ratio1:1) at doses of 100, 200, 400 and 800 mg in a double-blind, randomised, placebo-controlled, ascending-multiple-dose design. On days 2 and 7, a single dose of levodopa/benserazide 100/25 mg was given 1 h after the first intake of tolcapone. Plasma concentrations of tolcapone, its metabolite 3-O-methyltolcapone, levodopa and 3-O-methyldopa were determined during the course of the study in conjunction with COMT activity in erythrocytes. Results: Tolcapone was well tolerated at all dose levels, with a slight increase in gastrointestinal adverse events in females at higher doses. The drug was rapidly absorbed and eliminated and showed no changes in pharmacokinetics with time during multiple doses of 100 and 200 mg t.i.d. At doses of 400 and 800 mg t.i.d., tolcapone accumulated moderately as reflected in increased Cmax and AUC values. Despite the long half-life of 3-O-methyltolcapone (39 h), only minor accumulation occurred due to suppression of its formation by tolcapone. The pharmacodynamics of tolcapone did not change during the week of treatment as reflected in inhibition of COMT activity in erythrocytes, the derived parameters of the plasma concentration-effect relationship (inhibitory Emax model with constant EC50 values) and the effect on levodopa pharmacokinetics (1.6 to 2.5-fold increase in bioavailability). This suggests the absence of tolerance development and the insignificance of the altered pharmacokinetics at 400 and 800 mg t.i.d. with regard to the pharmacodynamics. Conclusion: The results of this study offer promising perspectives for the application of tolcapone as adjunct therapy to levodopa in the treatment of Parkinson’s disease.
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    A comparison of the pharmacokinetics and pharmacodynamics of cilazapril between Chinese and Caucasian healthy, normotensive volunteers (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 57-62 
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    ISSN: 1432-1041
    Keywords: Key words Cilazapril ; Caucasians ; Chinese; cilazaprilat ; pharmacokinetics ; pharmacodynamics ; ACE inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract. Methods: The pharmacokinetics and pharmacodynamics of the angiotensin converting enzyme (ACE) inhibitor cilazapril were studied in 12 Chinese and 13 Caucasian, healthy, normotensive volunteers on their normal diet. Cilazapril was given orally as a single 2.5 mg capsule. Plasma was sampled for assay of the active metabolite, cilazaprilat, plasma renin activity (PRA), aldosterone, angiotensin I (AI) and ACE-activity. Plasma concentrations of the active drug were measured by radioimmunoassay. Blood pressure and heart rate were measured at regular intervals. Results: The pharmacokinetic parameters of cilazaprilat were similar in the two ethnic groups. No significant difference in plasma concentrations was found at any of the time points. However, the weight-adjusted plasma clearance was significantly higher in the Chinese group, which is compatible with their lower body weight. The effects on plasma hormones were also comparable, although there was a somewhat greater rise in PRA and greater fall in aldosterone levels in Chinese than in Caucasians. The effect of cilazapril on blood pressure and heart rate was greater than was previously reported in healthy volunteers. Systolic (SBP) and diastolic (DBP) blood pressure were significantly reduced in both groups, but there was a more prolonged reduction in DBP in Caucasians. In addition, heart rate (HR) was significantly increased from baseline from 5 h onwards in Chinese subjects and significantly higher in comparison with Caucasians at most time points from 1.5 h onwards. The pharmacokinetic parameters of cilazapril were essentially the same in healthy, normotensive Chinese and Caucasians. Cilazapril reduced blood pressure acutely in both groups, with good tolerance. The inhibition of ACE in relationship to time and the plasma concentrations of cilazaprilat were similar in the two groups, although the changes in PRA and aldosterone suggest an ethnic difference in the responses of the renin-angiotensin-aldosterone system.
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    URL: http://dx.doi.org/10.1007/s002280050069
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    Pharmacokinetic interaction between cyclosporine and the dihydropyridine calcium antagonist felodipine (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 203-208 
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    ISSN: 1432-1041
    Keywords: Key words Cyclosporine ; Felodipine; dehydrofelodi-pine ; pharmacokinetics ; blood pressure ; drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: In a double blind, randomised, placebo-controlled, cross-over study 12 healthy male volunteers were allocated to receive felodipine + placebo, cyclosporine + placebo, and felodipine + cyclosporine in order to investigate the interaction between the calcium channel blocker felodipine and cyclosporine as it affects the pharmacokinetics of felodipine, dehydrofelodipine, and cyclosporine, and 24-hour blood pressure measurements. Methods: Single doses of cyclosporine (capsules, 5 mg/kg body weight) and of felodipine (extended release (ER) tablets 10 mg) were given at a 1–2 week interval. Plasma drug concentrations were followed for 2 days after drug intake. Results: For cyclosporine, Cmax was increased after combined treatment (16%) compared to cyclosporine alone, but felodipine did not influence other kinetic parameters of cyclosporine. For felodipine, combined treatment with cyclosporine and felodipine increased AUC and Cmax (58% and 151%, respectively) and lowered mean residence time (24%) significantly compared to felodipine alone. For the metabolite dehydrofelodipine, too, AUC and Cmax were increased after the combined treatment (43% and 94%, respectively). Mean 24-hour systolic and diastolic blood pressures were significantly lower after felodipine, both when felodipine was given alone (121/68 mmHg) and in combination with cyclosporine (122/68 mmHg) compared to cyclosporine alone (127/73 mmHg). Conclusion: A combined single dose of cyclosporine and felodipine in healthy subjects increased the AUC and Cmax of felodipine suggesting a cyclosporine-induced decrease in the first-pass metabolism of felodipine, whereas the AUC of cyclosporine was only slightly increased by felodipine.
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    Effect of food on the bioavailability of oxybutynin from a controlled release tablet (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 221-223 
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    ISSN: 1432-1041
    Keywords: Key words Oxybutynin; effect of food ; N-desethyl oxybutynin ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The effect of food on the bioavailability of oxybutynin was assessed in a randomised cross-over study in 23 healthy volunteers. A single oral 10 mg dose of a controlled release oxybutynin tablet was administered after a high fat breakfast and to fasting subjects. The AUC, Cmax, tmax, t1/2 and MRT of oxybutynin and its active metabolite N-desethyloxybutynin were determined. Results: Breakfast did not change the AUC of oxybutynin but increased the AUC of N-desethyloxybutynin by about 20% . The Cmax of oxybutynin and N-desethyl oxybutynin were two-fold higher when the drug was administered after breakfast compared to the fasting state. Conclusion: Breakfast significantly reduced the MRT of oxybutynin and N-desethyloxybutynin.
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    Plasma concentrations and pharmacokinetics of idebenone and its metabolites following single and repeated doses in young patients with mitochondrial encephalomyopathy (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 167-169 
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    ISSN: 1432-1041
    Keywords: Key words Idebenone; mitochondrial encephalomyopathy ; young patients ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The pharmacokinetics and tolerance of idebenone after single or repeated doses have been studied in young patients with mitochondrial encephalomyopathy. Results: No significant adverse effects were noted. In 3 out of 7 patients idebenone induced overall stimulation and improvement in arousal. Plasma concentrations of idebenone and its main metabolites were determined and the pharmacokinetic parameters of idebenone after single and repeated doses were estimated. During the single dose study, the mean plasma concentrations of idebenone and its main metabolites and mean pharmacokinetic parameters were comparable to published results (Cmax = 452.2 ng ⋅ ml−1, tmax = 2.3 h, AUC = 26 μg ⋅ ml−1 ⋅ h, t1/2β = 16.5 h). During the repeated doses study, no significant difference was found between mean residual plasma concentrations of idebenone on Day 2 (47 ng ⋅ ml−1) and Day 5 (70.6 ng ⋅ ml−1), and mean t1/2β of idebenone after the single and after repeated dose studies, i.e., there was no evidence of accumulation. Although idebenone did not appear to accumulate during this study, the coadministration of anticonvulsants, often prescribed during mitochondrial encephalomyopathy, can affect its pharmacokinetics.
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    Single oral doses of amisulpride do not enhance the effects of alcohol on the performance and memory of healthy subjects (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 161-166 
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    ISSN: 1432-1041
    Keywords: Key words Amisulpride; ethanol vector ; performance ; memory ; cognitive function ; interaction ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objectives: Amisulpride is a benzamide antipsychotic that binds selectively to dopamine D2- and D3-receptors, preferentially in limbic and hippocampal structures. Since other substituted benzamides have a limited or negligible interaction with alcohol on human performance, amisulpride was studied for this potential. Methods: In a randomised double-blind crossover study, 18 young, non-smoking men took single oral doses of placebo and amisulpride 50 mg and 200 mg, without and with ethanol (0.8 g ⋅kg−1) taken 30 min later. Objective performance tests and self-ratings were done at baseline and 1.5, 3.5 and 6.5 h after drug intake. Memory (immediate and delayed recall) was tested 2 h after dosing. Breath ethanol and the plasma concentrations of amisulpride and prolactin were measured. Three-way ANOVA + Newman-Keul tests were used for statistical analyses; interactions were confirmed by factorial contrast ANOVA. Results: Mean blood ethanol was 0.94, 0.62 and 0.26 g ⋅l−1 at the three test times. It produced significant impairment in all performance tests (symbol digit substitution, simulated driving, body sway, flicker fusion, tapping, nystagmus), reduced both immediate and delayed recall in memory tests, and caused subjective clumsiness, muzziness and mental slowness, mainly between 1.5 to 4.5 h after dosing. Amisulpride, 50 and 200 mg elevated plasma prolactin but had minimal or no effect on performance, attention and memory. The decreases in immediate free recall after the 50 mg dose and in delayed free recall after the 200 mg dose were slight. Amisulpride neither modified blood ethanol concentrations nor enhanced the detrimental effect of ethanol on skilled and cognitive performance; it slightly antagonised ethanol in the digit copying test. Ethanol did not modify the effect of amisulpride on plasma prolactin, and the plasma concentrations of amisulpride were little changed by ethanol. Conclusions: Amisulpride in single oral doses of 50 and 200 mg did not interact significantly with the effects of high, moderate or low concentrations of ethanol on human skilled and cognitive performance. The drugs did interact pharmacokinetically.
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    Comparison between concentrations of racemic mefloquine, its separate enantiomers and the carboxylic acid metabolite in whole blood serum and plasma (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 171-173 
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    ISSN: 1432-1041
    Keywords: Key words Mefloquine; mefloquine enantiomers ; carboxylic acid metabolite ; blood concentrations ; pharmacokinetics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To compare concentrations of the separate enantiomers of mefloquine (MQ), total racemic MQ and the carboxylic acid metabolite in different blood fractions at steady state. Setting: Human volunteer laboratory, Unit of Clinical Pharmacology, Karolinska Institute. Volunteers: Ten healthy adult Caucasian volunteers. Methods: Drug concentrations were determined by high-performance liquid chromatography (HPLC). Results: Trough concentrations of the (+)RS enantiomer were higher in venous whole blood than in plasma and serum (mean ratios, 1.41 and 1.38). For the other enantiomer, (−)SR, concentrations were lower in whole blood than in plasma (mean ratio 0.89) and for the metabolite this ratio was 0.5. Conclusion: Stereoselective distribution might be important for antimalarial activity and should be considered when pharmacokinetic studies are performed.
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    Pharmacokinetics of dexamethasone in premature neonates (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 477-483 
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    ISSN: 1432-1041
    Keywords: Dexamethasone ; Premature neonates ; pharmacokinetics ; bronchopulmonary dysplasia ; infant ; newborn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Dexamethasone is frequently used in premature neonates with bronchopulmonary dysplasia, however little is known about its disposition in this population. Methods: We evaluated the pharmacokinetics of dexamethasone in 9 premature neonates with a mean gestational age of 27.3 weeks and a postnatal age of 21.8 days. Results: There was a strong relationship between clearance (4.96 ml·min−1·kg−1) and gestational age (r=0.884). Pharmacokinetic parameters were grouped based on a gestational age of less than 27 weeks (Group I) and greater than 27 weeks (Group II). Mean clearance in group I and group II was 1.69 and 7.57 ml·min−1·kg−1, respectively. Mean distribution volume in group I and II was 1.26 and 2.19 l·kg−1, respectively. No significant relationships were noted between the disposition of dexamethasone and ventilator requirements or adverse effects. Conclusion: The pharmacokinetics of dexamethasone in premature neonates was related to gestational age.
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    Influence of food on the bioavailability and some pharmacokinetic parameters of diprafenone – a novel antiarrhythmic agent (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 315-319 
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    ISSN: 1432-1041
    Keywords: Key words Diprafenone; antiarrhythmics ; bioavailability ; human ; foods ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The present study was done to investigate the effect of food on the bioavailability of diprafenone. Methods: The most important pharmacokinetic parameters (Cmax, t1/2, AUC) and the relative oral availability of a solid oral preparation of racemic diprafenone were investigated when administered to fasting subjects and 10 min after a standard meal, in an open, randomised, crossover trial. Single oral doses of 100 mg were given on two different occasions, at least 1 week apart. The serum concentrations of diprafenone and its hydroxy-metabolite were determined up to 24 hours after administration by a sensitive, specific HPLC method. Fifteen healthy, male volunteers were enrolled in the trial. Their mean height, weight and age were 183 cm, 80 kg and 22 years, respectively. Fourteen volunteers were found to be rapid hydroxylators and one was a slow hydroxylator of debrisoquine. Only data from the rapid hydroxylators were used in the statistical analysis. Results: Food increased the oral bioavailability of diprafenone by approximately 50%. This effect was similar in rapid and in slow hydroxylators. The only slow hydroxylator in this trial had an AUC0–last ratio (with food/fasting) of 1.54. These findings suggest that diprafenone should be administered in a constant temporal relationship to food.
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    Evaluation of plasma and urinary salbutamol levels in COPD (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 91-93 
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    ISSN: 1432-1041
    Keywords: Key words Salbutamol; nebulised ; pharmacokinetics ; COPD ; overnight urinary salbutamol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To evaluate the use of trough plasma salbutamol and overnight urinary salbutamol excretion in the assessment of nebulised salbutamol delivery in patients with chronic obstructive pulmonary disease (COPD). Methods: Twenty in-patients with COPD receiving nebulised salbutamol, age 69.7 years, FEV1 38.1% predicted, were studied on two consecutive days, receiving four 2.5 mg doses of nebulised salbutamol on day 1 and four 5 mg doses of nebulised salbutamol on day 2, the first dose at 8.00 h the last dose at 22.00 h. Salbutamol delivery was assessed after the last dose by trough plasma salbutamol 8.00 h and overnight urinary excretion of salbutamol (22.00–8.00 h). Results: Levels of urinary salbutamol were detectable in all 20 patients at both doses, whereas for plasma salbutamol detectable levels were only found in 16/20 cases at the 2.5 mg dose and in all cases at the 5 mg dose. For overnight urinary salbutamol (μg⋅10 h−1  n = 20) the results were 141 for 2.5 mg and 249 for 5 mg. The dose ratio for urinary salbutamol between 2.5 mg and 5 mg doses was 1.83. Results for plasma salbutamol (ng/ml, n = 16) were 1.58 at 2.5 mg and 2.43 at 5 mg: dose ratio (geometric mean) 1.49. Conclusion: Overnight urinary salbutamol provides a simple and effective measure of nebulised salbutamol delivery in patients with COPD, which would be suitable for studying nebuliser performance and compliance.
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    Therapeutic monitoring of nalbuphine: transplacental transfer and estimated pharmacokinetics in the neonate (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 485-489 
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    ISSN: 1432-1041
    Keywords: Key words Nalbuphine ; Neonate; therapeutic drug monitoring ; placental transfer ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Nalbuphine, a mixed agonist-antagonist opiate, is commonly used as a systemic analgesic during labour. Recent reports of perinatal adverse effects prompted us to carry out therapeutic nalbuphine monitoring in obstetric analgesia. Because data on fetomaternal transfer are scarce and the pharmacokinetics of this drug in the neonate are largely unknown, we report data obtained from 28 parturients treated with nalbuphine either intramuscularly and/or intravenously during labour. Plasma nalbuphine levels were measured by high-performance liquid chromatography (HPLC) with electrochemical detection. At delivery, 30–150 min after maternal administration, nalbuphine concentrations ranged from 5.0 to 79.2 ng ⋅ ml−1 in mother plasma samples and from 3.0 to 46.6 ng ⋅ ml−1 in umbilical cord plasma samples. Nalbuphine concentrations were highly correlated to dose. The fetomaternal ratio was high: 0.74 and not correlated to the administered dose of nalbuphine. An estimated plasma half-life of 4.1 h was calculated from two determinations in the neonate based on the assumption of a monoexponential decay of nalbuphine concentrations. Apart from a flattening of the fetal heart rate tracing in 54% of the cases, only one neonate had a low Apgar score at birth. The apparent prolonged half-life of nalbuphine in the neonate indicates the usefulness of an intramuscular injection of naloxone to prevent recurrence of cardiorespiratory depression due to nalbuphine administration to the mother.
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  • 50
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    Therapeutic monitoring of nalbuphine: transplacental transfer and estimated pharmacokinetics in the neonate (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 485-489 
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    ISSN: 1432-1041
    Keywords: Nalbuphine ; Neonate ; therapeutic drug monitoring ; placental transfer ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Nalbuphine, a mixed agonist-antagonist opiate, is commonly used as a systemic analgesic during labour. Recent reports of perinatal adverse effects prompted us to carry out therapeutic nalbuphine monitoring in obstetric analgesia. Because data on fetomaternal transfer are scarce and the pharmacokinetics of this drug in the neonate are largely unknown, we report data obtained from 28 parturients treated with nalbuphine either intramuscularly and/or intravenously during labour. Plasma nalbuphine levels were measured by high-performance liquid chromatography (HPLC) with electrochemical detection. At delivery, 30–150 min after maternal administration, nalbuphine concentrations ranged from 5.0 to 79.2 ng·ml−1 in mother plasma samples and from 3.0 to 46.6 ng·ml−1 in umbilical cord plasma samples. Nalbuphine concentrations were highly correlated to dose. The fetomaternal ratio was high: 0.74 and not correlated to the administered dose of nalbuphine. An estimated plasma half-life of 4.1 h was calculated from two determinations in the neonate based on the assumption of a monoexponential decay of nalbuphine concentrations. Apart from a flattening of the fetal heart rate tracing in 54% of the cases, only one neonate had a low Apgar score at birth. The apparent prolonged half-life of nalbuphine in the neonate indicates the usefulness of an intramuscular injection of naloxone to prevent recurrence of cardiorespiratory depression due to nalbuphine administration to the mother.
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    Pharmacokinetics of quinine in patients with chronic renal failure (1996)
    Springer
    European journal of clinical pharmacology 49 (1996), S. 497-501 
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    ISSN: 1432-1041
    Keywords: Quinine ; Malaria ; pharmacokinetics ; chronic renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Methods: We investigated the pharmacokinetics of quinine (Qn) following administration of a single oral dose of 600 mg Qn sulphate in six male Thai patients with a moderate degree of chronic renal failure (CRF), and six male Thai subjects with normal renal function. Results: The drug was well tolerated in both groups of subjects; no major adverse reactions were observed. A marked alteration in the pharmacokinetics of Qn was found in patients with CRF compared to healthy subjects; there were six signifiicant changes in the pharmacokinetic parameters. Absorption was delayed, but increased in CRF (tmax 4.5 vs 1.6 h, Cmax 6.17 vs 3.45 μg·ml−1). Total clearance was significantly reduced 0.94 vs 2.84 ml·min−1·kg−1, whereas Vz/f remained unchanged (1.82 vs 2.78 1·kg−1). This resulted in the increased values of AUC and prolongation of the t1/2z and MRT in the patients (AUC 181.5 vs 61.8 μg·min−1·ml−1, t1/2z 26 vs 9.7 h, MRT 36.4 vs 11.3 h). Median concentrations of plasma unbound fraction of Qn collected at 4 h after drug administration in patients and healthy subjects were 7.3 vs 9.8%, respectively.
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    Stereoselective pharmacokinetics of mefloquine in young children (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 241-244 
    Details
    ISSN: 1432-1041
    Keywords: Key words Mefloquine ; Children; enantiomer ; pharmacokinetics ; stereoselectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: the stereospecificity of mefloquine pharmacokinetics in children has been investigated. Patients: Twelve children aged 6 to 24 months were treated for uncomplicated falciparum malaria with a single oral dose of 25 mg⋅kg−1 racemic mefloquine in combination with sulfadoxine and pyrimethamine. Methods: concentrations of mefloquine enantiomers were determined using a coupled achiral-chiral chromatographic system. Pharmacokinetic parameters were calculated using model-independent analysis. Results: Maximum plasma concentrations, areas under the curve and apparent plasma elimination half-lives were higher for the (−) enantiomer than its antipode. In contrast, the apparent volume of distribution (V/f) and total clearance (Cl/f) values were higher for the (+) enantiomer. Conclusion: the stereoselectivity of mefloquine pharmacokinetics is similar to that observed in adults.
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    A single dose of ursodiol does not affect cyclosporine absorption in liver transplant patients (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 335-337 
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    ISSN: 1432-1041
    Keywords: Key words Cyclosporine ; Ursodiol; ursodeoxycholic acid ; absorption ; pharmacokinetics ; liver transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To study the possible influence of ursodiol (ursodeoxycholic acid), a hydrophilic bile acid, on cyclosporine (CsA) bioavailability. Methods: Seven adult liver transplant recipients participated in a randomised cross-over pharmacokinetic study comparing ursodiol (600 mg) with placebo in single doses. Blood concentrations of CsA were measured by HPLC. Results: There was no significant effect of ursodiol on CsA absorption: AUC was 5011 vs 5486 ng⋅h⋅ml–1, Cmax was 832 vs 871 ng⋅ml–1 and tmax was 2 vs 2 h, after ursodiol and placebo, respectively. Conclusion: Although a significant period effect was observed, we conclude that a single dose of ursodiol has little effect on CsA absorption in liver transplant patients and that an interaction in the intestinal lumen between these two drugs is unlikely.
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    Absolute bioavailability of fluoride from disodium monofluorophosphate and enteric-coated sodium fluoride tablets (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 321-326 
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    ISSN: 1432-1041
    Keywords: Key words Sodium fluoride ; Disodium monofluorophosphate; absolute bioavailability ; pharmacokinetics ; elderly population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objectives: The absolute bioavailability and other pharmacokinetic parameters of two fluoride formulations were investigated in 13 healthy volunteers, aged 61–70 years. Methods: The following formulations were administered, under fasting conditions, in a single-dose three-way cross-over design: tablets of 76 mg disodium monofluoro phosphate (MFP, equivalent to 10.0 mg F− ion), enteric-coated (e.c.) tablets of 25 mg sodium fluoride (NaFor, equivalent of 11.3 mg F− ion), and an isoosmotic aqueous injection solution (4 ml) of 22.1 mg sodium fluoride (NaFiv, equivalent of 10.0 mg F− ion). There was a wash-out period of at least one week between each administration. Blood was sampled before and during a 24-hour period after administration. For F− excretion urine was sampled 48 hours before (baseline) and over the 48 hours after the adminstration. Results: The mean t1/2 values of the three formulations were 8.3, 8.7 and 8.3 h for MFP, NaFor and NaFiv respectively, and were not significant different. Mean Cmax after MFP was significantly higher than after NaFor [344 vs 142 μg⋅l−1]. Mean tmax for MFP was shorter than for NaFor [1.1 vs 4.6 h]. MFP had significantly higher bioavailability [102.8%] than NaFor [64.2%]. Conclusion: The MFP formulation showed higher bioavailability with smaller variation than the NaFor formulation. MFP is preferable, therefore, for fluoride therapy in clinical practice, and changing from NaFor to MFP will require adjustment of the dose.
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    Bioavailability of 1-deamino-8-D-arginine vasopressin with an enzyme inhibitor (aprotinin) from the small intestine in healthy volunteers (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 491-495 
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    ISSN: 1432-1041
    Keywords: Key words Aprotinin ; Arginine vasopressin; bioavailability ; dDAVP ; enzyme inhibitor ; gastrointestinal tract ; healthy volunteer ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The bioavailability of an aqueous solution of 1-deamino-8-D-arginine vasopressin (dDAVP), with and without an enzyme inhibitor, was studied in six healthy, male volunteers aged 19–34 years, followed for 8 h after each drug administration. Methods: For i.v. administration the subjects received 4 μg dDAVP. For intestinal administration 500 μg dDAVP was administered directly, in two separate sessions, in the first part of the duodenum via a triple-lumen channel tube. In one session a solution of isotonic polyethylene glycol (PEG) was given as a continuous enteral perfusion. In the other session a solution of PEG and aprotinin was administered enterally at the constant rate of 5 ml⋅min−1 for 4 h. Plasma dDAVP was measured using a specific, sensitive radioimmunoassay and intestinal juice was collected for measurement of lipase, chymotrypsin and pH every 30 min for 5 h. Results: The intestinal chymotrypsin activity was decreased after perfusion of aprotinin while the lipase activity was not modified. After i.v. administration, the half-life of elimination of dDAVP was 1.56 h and plasma clearance 1.24 ml⋅min⋅kg−1. The mean bioavailability after duodenal administration of dDAVP + aprotinin was 0.46% compared with 0.09% after duodenal administration of dDAVP alone. The bioavailability of dDAVP after direct duodenal administration of an aqueous solution was similar to that after swallowing a tablet in a previous study and increased 5 times when given together with a perfusion of an enzyme inhibitor.
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    Bioavailability of estradiol from a new matrix and a conventional reservoir-type transdermal therapeutic system (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 327-330 
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    ISSN: 1432-1041
    Keywords: Key words Hormone replacement therapy; estradiol ; pharmacokinetics ; bioequivalence ; postmenopausal volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Bioavailability of estradiol delivered from a newly developed matrix-type transdermal therapeutic system (MTTS) was compared with that of the conventional reservoir-type system (RTTS). Both formulations have a nominal delivery rate of 50 μg per day of 17β-estradiol (E2). Plasma concentrations of E2 and estrone (E1) were determined at steady state during a 96-h application of each formulation to 34 postmenopausal volunteers, using a two-stage randomized two-period crossover design. Results: The MTTS proved to be equivalent to the RTTS with respect to the extent of E2 absorption. Due to differences in patch design and composition, the rate of absorption was different between the two systems, with less fluctuating E2 plasma levels during application of the matrix system. Local tolerability and adhesion of MTTS appeared to be better than those of the reservoir system.
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    Effect of itraconazole on the pharmacokinetics and pharmacodynamics of zopiclone (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 331-334 
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    ISSN: 1432-1041
    Keywords: Key words Zopiclone ; Itraconazole; drug interaction ; pharmacokinetics ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: We studied the possible interaction between itraconazole, a potent inhibitor of CYP3A, and zopiclone, a short-acting hypnotic. Methods: A double-blind, randomized, two-phase crossover design was used. Ten healthy young subjects received daily either 200 mg itraconazole or placebo for 4 days. On day 4 they ingested a single 7.5-mg oral dose of zopiclone. Plasma concentrations of zopiclone and itraconazole were determined and pharmacodynamic responses were measured up to 17 h. Results: Itraconazole significantly increased the Cmax of zopiclone from 49 to 63 ng ⋅ ml−1. The t1/2 of zopiclone was prolonged from 5.0 to 7.0 h. The AUC(0–∞) of zopiclone was increased from 415 to 719 ng ⋅ ml−1 h by itraconazole. No statistically significant differences were observed in the pharmacodynamic responses between the groups. Conclusion: Itraconazole has a statistically significant pharmacokinetic interaction with zopiclone but this is only of limited clinical importance, at least in young adults.
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    Effects of heat exposure in a Finnish sauna on the pharmacokinetics and metabolism of midazolam (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 335-338 
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    ISSN: 1432-1041
    Keywords: Key words Midazolam ; Sauna; metabolism ; pharmacokinetics ; heat ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The effect of short-term heat exposure in a Finnish sauna on hepatic first-pass metabolism and the capacity to metabolize midazolam were studied in a crossover trial. Midazolam oral (15 mg) and intravenous (0.05 mg ⋅ kg−1) was given to 6 healthy young male volunteers, in random order, during a control session and a sauna bathing session (temperature 85–100° C, relative humidity 25–30%). Blood samples for the determination of plasma midazolam and α-hydroxy midazolam concentrations were taken for 6 h after drug administration. Results: After oral administration, the bioavailability and clearance of midazolam were not affected by sauna bathing, nor was there a significant difference in α-hydroxy midazolam plasma concentration or the α-hydroxy midazolam/midazolam AUC-ratio between the sessions. Midazolam Cmax was increased and its t1/2β was prolonged during the sauna session, but the clinical relevance of the findings appears to be modest. The pharmacokinetics of intravenous midazolam were not affected by sauna bathing. Conclusions: Short-term heat exposure may not affect the first-pass metabolism or hepatic capacity to metabolize midazolam.
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    Desulforhopalus vacuolatus gen. nov., sp. nov., a new moderately psychrophilic sulfate-reducing bacterium with gas vacuoles isolated from a temperate estuary (1996)
    Springer
    Archives of microbiology 166 (1996), S. 160-168 
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    ISSN: 1432-072X
    Keywords: Key words Anaerobic sulfate reduction ; Incomplete ; propionate oxidation ; Marine environment ; Low ; temperature ; Psychrophilic bacteria ; Growth yields ; Desulforhopalus vacuolatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new type of gas-vacuolated, sulfate-reducing bacterium was isolated at 10° C from reduced mud (E0 〈 0) obtained from a temperate estuary with thiosulfate and lactate as substrates. The strain was moderately psychrophilic with optimum growth at 18–19° C and a maximum growth temperature of 24° C. Propionate, lactate, and alcohols served as electron donors and carbon sources. The organism grew heterotrophically only with hydrogen as electron donor. Propionate and lactate were incompletely oxidized to acetate; traces of lactate were fermented to propionate, CO2, and possibly acetate in the presence of sulfate. Pyruvate was utilized both with and without an electron acceptor present. The strain did not contain desulfoviridin. The G+C content was 48.4 mol%. The differences in the 16S rRNA sequence of the isolate compared with that of its closest phylogenetic neighbors, bacteria of the genus Desulfobulbus, support the assignment of the isolate to a new genus. The isolate is described as the type strain of the new species and genus, Desulforhopalus vacuolatus.
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    Purification and characterization of fumarase from the syntrophic propionate-oxidizing bacterium strain MPOB (1996)
    Springer
    Archives of microbiology 165 (1996), S. 126-131 
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    ISSN: 1432-072X
    Keywords: Key words Fumarase ; Syntrophy ; Propionate ; oxidation ; Fumarate fermentation ; Anaerobic oxidation ; Iron-sulfur cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fumarase from the syntrophic propionate-oxidizing bacterium strain MPOB was purified 130-fold under anoxic conditions. The native enzyme had an apparent molecular mass of 114 kDa and was composed of two subunits of 60 kDa. The enzyme exhibited maximum activity at pH 8.5 and approximately 54° C. The K m values for fumarate and l-malate were 0.25 mM and 2.38 mM, respectively. Fumarase was inactivated by oxygen, but the activity could be restored by addition of Fe2+ and β-mercaptoethanol under anoxic conditions. EPR spectroscopy of the purified enzyme revealed the presence of a [3Fe-4S] cluster. Under reducing conditions, only a trace amount of a [4Fe-4S] cluster was detected. Addition of fumarate resulted in a significant increase of this [4Fe-4S] signal. The N-terminal amino acid sequence showed similarity to the sequences of fumarase A and B of Escherichia coli (56%) and fumarase A of Salmonella typhimurium (63%).
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    Carbon dioxide evolution of an upland rice and barley, double cropping field in central Japan (1996)
    Springer
    Ecological research 11 (1996), S. 217-227 
    Details
    ISSN: 1440-1703
    Keywords: double cropping field ; soil respiration ; temperature ; water content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carbon dioxide evolution rates from a double cropping, upland rice and barley field were determined in central Japan from June 1992 to May 1994, and regression models were developed to predict soil respiration rate. Diurnal patterns of hourly soil respiration rates (SRh) showed a similar trend with those of soil surface temperatures. Daily soil respiration rate (SRd) obtained by integrating SRh varied from 0.3 to 15.6 g CO2 m−2 for the 2 years. In the summer cropping period, SRd was positively correlated with daily mean soil surface temperature and negatively correlated with volumetric water content in soil. Moreover, this relationship was able to be expressed as a multiple-factor model with an Adj-R2 of 0.925. On the other hand, in the winter cropping period, SRd was able to be represented by a single factor model using soil surface temperature with an Adj-R2 of 0.854. Based on these relationships, seasonal changes in soil respiration rate were estimated. Total soil respiration rates in 1992 and 1993 estimated for the summer cropping period were 1260 g CO2 m−2 and 1094 g CO2 m−2, and for the winter cropping period 624 g CO2 m−2 and 676 g CO2 m−2, respectively. It was considered that the lower values during the summer cropping period in 1993 depended on lower soil surface temperature and higher soil water content.
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    Kinetic analysis of DSC and thermogravimetric data on combustion of lignite (1996)
    Springer
    Journal of thermal analysis and calorimetry 46 (1996), S. 1657-1669 
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    ISSN: 1572-8943
    Keywords: activation energy ; combustion ; differential scanning calorimetry ; kinetics ; lignite ; oxidation ; thermogravimetric analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal analysis increasingly being used to obtain kinetic data relating to sample decomposition. This work involves a comparative study of several methods used to analyse DSC and TG/DTG data obtained on the oxidation of Beypazari lignite. A general computer program was developed and the methods are compared with regard to their accuracy and the ease of interpretation of the kinetics of thermal decomposition. For this study, the ratio method was regarded as the preferred method, because it permits the estimation of reaction order, activation energy and Arrhenius constant simultaneously from a single experiment.
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    Contribution to the understanding of the parabolic oxidation mechanism of dilute alloys. Part I: Oxides with metal excess or oxygen deficit (1996)
    Springer
    Oxidation of metals 46 (1996), S. 1-17 
    Details
    ISSN: 1573-4889
    Keywords: dilute alloys ; oxidation ; Wagner-Hauffe rule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Concerning the parabolic oxidation of alloys with a low content of a different valence element, we show that the Wagner-Hauffe valence approach contains some inaccuracies. This paper is devoted to the growth of an oxide MO with metal excess or oxygen deficit. The analytical processing consists in solving the differential equation connecting the point defect flux to the oxygen pressure. This equation has been solved analytically in the case where the foreign-element concentration is very high compared to that of the point defects in the pure oxide. On this assumption with a lower-valence dopant, as long as the oxide conductivity remains essentially electronic, the oxidation is limited only by the transport of ionic defects across the scale under the electric-potential gradient. Moreover, an increase of the dopant concentration may lead to an oxide exhibiting partial ionic conductivity. Consequently, the parabolic constant variations as a function of the dopant concentration is not monotonic, contrary to results published before. With a higher-valence dopant, the conductivity always remains electronic, and this result agrees with predictions based on the Wagner Hauffe approach, though the demonstrations are fundamentally different.
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    Effect of short-circuiting on the oxidation kinetics of copper and its doped varieties in the temperature range of 523–1073 K (1996)
    Springer
    Oxidation of metals 46 (1996), S. 73-107 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; copper ; Li-doped copper ; Cr-doped copper ; short-circuiting ; Mott's parabola ; Wagner's parabola
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of shorting circuitry attachment between metal-oxide and oxideoxygen interfaces on the oxidation kinetics of copper, lithium-doped copper (Li: 400 ppm), and chromium-doped copper (Cr: 12 ppm) have been studied in dry air $$(P_{O_2 } = 21.27kPa)$$ in the temperature range of 523–1073 K. Oxide film or scale growth under short-circuiting as well as under normal oxidation conditions conforms to the parabolic rate law. The oxidation kinetics under short-circuiting resulted in decreased rates for Cu and Li-doped Cu up to a temperature of 773 K, while Cr-doped Cu exhibited an enhancement in rate compared to its normal oxidation in the same temperature range. However, above 873 K, all three systems under shorting circuitry attachment exhibited enhanced rates compared to their normal oxidation rates in conformity to the existing theoretical model. Use of additional resistances in series in the outer short-circuit Pt path have clearly established that below 773 K Mott's fieldinduced migration plays the most important role, while at elevated temperatures Wagner's electrochemical potential-gradient factor acts as the main driving force in the scale-growth process. The results have been interpreted on the basis of average defect concentration, the electrochemical potential gradient, electrical field gradient, and transport coefficient in the Cu2O layer.
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    Effect of Cr, Co, and Ti additions on the high-temperature oxidation behavior of Ni3Al (1996)
    Springer
    Oxidation of metals 46 (1996), S. 109-127 
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    ISSN: 1573-4889
    Keywords: oxidation ; Ni3Al base alloy ; chromium ; cobalt ; titanium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of Ni3Al+2.90 wt.% Cr, Ni3Al+3.35 wt% Co, and Ni3Al+2.99 wt.% Ti alloys was studied in 1 atm of air at 1000, 1100, and 1200°C. Isothermal tests revealed parabolic kinetics for all three alloys at all temperatures. Cyclic oxidation for 28 two-hour cycles produced little spallation at 1000°C, but caused partial spallation at 1100°C. Especially, at 1200°C severe spallation in all three alloys was observed. Although additions of Cr, Co, or Ti to Ni3Al alloys slightly increased the isothermal-oxidation resistance, the additions tended to decrease the cyclic-oxidation resistance. The major difference in the oxidation of the three alloys compared with the oxidation of pure Ni3Al alloys was the existence of small α-Al2O3 particles in the middle of the α-Al2O3 scale and the formation of irregularly shaped Kirkendall voids at the alloy-scale interface.
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    Influence of external mechanical loadings (creep, fatigue) on oxygen diffusion during nickel oxidation (1996)
    Springer
    Oxidation of metals 45 (1996), S. 153-181 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; 18O diffusion ; nickel ; stress effects on diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This study deals with the influence of various mechanical loadings (fatigue, creep, creep-fatigue) on oxygen diffusion in a particular system, oxidizing nickel. A distinction between the behavior of the oxide layer and underlying nickel was noted during the first step of oxidation at 550°C, in PO 2=1 atm. Mechanical loading causes a decrease of the oxygen mobility through the oxide scale (factor of 103). The oxide thicknesses on nickel undergoing mechanical loadings are different than for an unloaded sample, due to distinct contributions of the oxygen and nickel fluxes in the growing oxide. In the substrate, the ingress of oxygen becomes easier with a constant tensile load (creep). The intergranular-oxygen diffusion coefficient, Di, is increased by a factor of 102 with respect to other samples. In creep, oxygen diffusion takes place along grain boundaries of a structure with smaller grains than in unstrained Ni. A short fatigue period during creep-fatigue decreases the sensitivity of nickel to intergranular-oxygen diffusion.
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    Relationships between soluble sugar concentrations in roots and ecosystem stress for first year sugar maple seedlings (1996)
    Springer
    Water, air & soil pollution 88 (1996), S. 1-19 
    Details
    ISSN: 1573-2932
    Keywords: Acidic deposition ; vesicular-arbuscular mycorrhizae ; seedling nutrition ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Accumulation of reducing sugars (i.e., glucose and fructose) in plant roots has been consistently correlated with forest dieback and decline and, therefore, has potential as a biological indicator of ecosystem stress. In this study, the relationships between acidic deposition and “natural” (temperature, mycorrhizae, and nutrition) factors with first-year sugar maple seedling root sugar concentrations and growth were assessed in two sugar maple dominated forests in Michigan. Seedlings at the southern site (Wellston) had greater root growth, phosphorus, total sugar, and sucrose concentrations in roots, but lower reducing sugar concentration in roots. In addition, percent root length colonized by vesicular-arbuscular mycorrhizal fungi was less than that found for seedlings growing at the northern site (Alberta). Throughfall deposition of nitrate, sulfate, and hydrogen ions was not significantly correlated with seedling total or reducing sugar concentration. Total sugar concentration in seedling roots was positively correlated with air and soil temperatures at the southern site, but not at the northern site. Seedling tissue phosphorus concentration was correlated with total sugars at both sites, with sucrose at the southern site, and reducing sugars at the northern site. Mycorrhizal colonization rates at the Alberta site were positively correlated with reducing sugar concentration in seedling roots and negatively correlated with sucrose concentration. The results suggest that differences in seedling root sugar concentrations in these two forests are related to seedling root growth and are most likely due to ecological variables, such as available soil phosphorus, temperature, and growing season length through some complex interaction with mycorrhizae rather than acidic deposition stress.
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    A study on the oxidation characteristics of cast irons containing aluminum (1996)
    Springer
    Oxidation of metals 45 (1996), S. 109-131 
    Details
    ISSN: 1573-4889
    Keywords: Fe−Al−C ; Fe−Al−Si−C ; inoculation ; scale ; characterization ; oxidation ; high temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Isothermal-oxidation characteristics of cast irons containing aluminum (5–15% Al) from 700 to 1000°C in air have been studied. In addition to massgain measurements, the morphology and composition of the oxide scales have been examined by SEM-EDX system and XRD analysis. A normal Fe−5Al−C alloy does not develop protective, adherent scales. Even the addition of misch metal and calcium silicide to such an alloy does not improve its oxidation resistance. But aluminum cast iron develops considerable oxidation resistance only when a sufficient quantity of silicon is also present in the alloy. Treatment of the alloy with misch, metal and calcium silicide together assists in protective scale formation. Among the alloys investigated Fe−15Al−Si−C treated with misch metal and calcium silicide shows minimum oxidation at 1000°C.
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    Corrosion of iron in sulfur dioxide at 0.1 MPa (1996)
    Springer
    Oxidation of metals 45 (1996), S. 469-486 
    Details
    ISSN: 1573-4889
    Keywords: iron ; sulfur dioxide ; oxidation ; tracer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The reaction of iron with sulfur dioxide at 0.1 MPa and 1073 K was studied. The composition and morphology of the scales, transport phenomena occurring in the growing scales, and kinetics of the process were investigated. Scanning electron microscopy and various techniques of X-ray analysis were used. The transport phenomena were studied by marker and by radiotracer techniques. The scales were composed of sulfide and oxides and grew by the outward diffusion of metal. It was concluded that the process initially took place through the reaction of iron with sulfur dioxide molecules. During the next stage of the process the reaction with sulfur dioxide molecules as well as with oxygen molecules is possible.
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    URL: http://dx.doi.org/10.1007/BF01046847
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    High-temperature corrosion of Ti and Ti-6Al-4V alloy (1996)
    Springer
    Oxidation of metals 45 (1996), S. 507-527 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; sulfidation ; oxides ; sulfides ; Ti ; Ti-6Al-4V alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Pure titanium and Ti-6Al-4V were exposed at 750°C in an H2/H2O/H2S PO 2≈10−18 Pa and PS 2≈10−1 Pa), H2/H2O (PO 2≈10−18 Pa) and air environments for up to 240 hr. The corrosion kinetics, obtained by the discontinuous gravimetric method, showed that the sulfidation/oxidation kinetics were linear for Ti and linear-parabolic for Ti-6Al-4V in the H2/H2O/H2S environment. Both materials obeyed parabolic rate laws in the H2/H2O atmosphere after a transient period, and linear-parabolic rate laws in air. After exposure to the H2/H2O/H2S atmosphere, the titanium specimen displayed a double scale of TiO2 with an intervening TiS2 film between the double-layered scale of TiO2 and the substrate. Ti-6Al-4V also contained a double layer of TiO2 together with a stratum consisting of Al2S3, TiS2 and vanadium sulfide at the junction of the inner TiO2 layer and substrate. Some Al2O3 precipitated in the external portion of the outer TiO2 layer. Following oxidation in the low-PO 2 atmosphere a double-layered oxide of TiO2 scale formed on both Ti and Ti-6Al-4V. The scale on Ti-6Al-4V also contained an α-Al2O3 film situated between the outer and inner (TiO2) layers. For both materials, multilayered-scale formation characterized air oxidation. In detail a multilayered oxide scale of TiO2 formed on the air-oxidized Ti, while a multilayered oxide scale with alternating layers of Al2O3/TiO2 developed on Ti-6Al-4V oxidized in air.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046849
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    Mixed oxidant corrosion in nonequilibrium gasifier environments (1996)
    Springer
    Oxidation of metals 45 (1996), S. 487-505 
    Details
    ISSN: 1573-4889
    Keywords: sulfidation ; oxidation ; gasification ; austenitic steel alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The major use of high-temperature steel alloys in gasifiers is in heat exchangers for cooling hot syngas, consisting mainly of CO and H2 with lesser amounts of H2O and CO2 and minor quantities of H2S and HCl. Metal temperatures range from 250 to 600°C, gas temperatures from 250 to 1200°C. Because of rapid cooling the composition of the gas does not change with temperature. Therefore the gas is not in equilibrium at the metal surface. Calculations show that such gases have lower oxygen and sulfur pressures than equilibrated gases at the same temperature. This makes the results of previous laboratory studies less appropriate for predicting mixed oxidant corrosion in gasifiers. For this reason the present study was carried out using nonequilibrium gas mixtures, similar to gases, produced in entrained-slagging gasifiers. Most corrosion experiments were carried out at 540°C, as this is a common temperature for superheaters and hot-gas cleanup systems. Iron-base model alloys containing 35% Ni, 20% Cr, and various minor alloying additions were studied. Three corrosion regimes were identified over the range of conditions studied, depending on the sulfur-to-oxygen pressure ratio of the gas and the alloy composition. At high PS 2/PO 2 ratios a somewhat protective FeCr2S4 scale formed on all alloys. Below this layer internal oxidation and sulfidation occurred at a slow rate. At lower PS 2/PO 2 ratios nonprotective Fe(Ni, Cr)S external scales formed. These allow rapid internal oxidation of the chromium in the alloy, resulting in high corrosion rates. Under the same conditions very low corrosion rates are obtained when silicon is added to the alloy, because the presence of SiO2 precipitates makes the internal-oxidation layer protective. Thus, the same corrosion model is operative in all three corrosion regimes: external sulfidation of iron and nickel, together with internal oxidation of chromium and other strong-oxide formers.
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    URL: http://dx.doi.org/10.1007/BF01046848
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    TEM investigations of the early stages of TiAl oxidation (1996)
    Springer
    Oxidation of metals 46 (1996), S. 255-285 
    Details
    ISSN: 1573-4889
    Keywords: electron diffraction ; intermetallic ; oxidation ; TEM ; titanium aluminide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The early stages of TiAl oxidation at 900°C and 1000°C in air have been investigated by transmission electron microscopy (TEM). The investigations revealed that at the beginning of oxidation, i.e., after 4 min, TiO2 and Al2O3 grow in a preferential orientation on the γ-TiAl substrate. After 4 h of oxidation an oxide scale structure can already be found similar to that known from long-term oxidation. In addition, besides α-Al2O3, the formation of a second aluminum oxide phase and of titanium nitrides is observed. The processes at the metal-oxide interface of oxidation in the early stages, consisting of a repeated cycle of Al2O3 formation, Al2O3 dissolution, outward migration of Al through the scale, and reprecipitation of Al2O3 in the outer scale, are described by a model. The four stages observed in the kinetics of TiAl oxidation are explained on the basis of the results obtained and the structure of the oxide scale.
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    URL: http://dx.doi.org/10.1007/BF01050799
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    The corrosion of pure niobium in oxidizing, sulfidizing, and oxidizing-sulfidizing gas mixtures at 600–800°C (1996)
    Springer
    Oxidation of metals 46 (1996), S. 287-297 
    Details
    ISSN: 1573-4889
    Keywords: pure niobium ; oxidation ; sulfidation ; oxidation-sulfidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The corrosion of pure niobium has been studied at 600–800°C in various environments as part of a study of the corrosion resistance of its alloys with iron, cobalt, and nickel to atmospheres of low-oxygen and/or high-sulfur activities. The results have shown that not only the sulfidation but also the corrosion in mixed atmospheres and particularly the oxidation under low oxygen pressures of pure niobium are quite slow, with kinetics rather similar in the three types of gas mixtures used. The good corrosion resistance of niobium to attack by oxygen under low pressures is quite interesting because this element is corroded very rapidly by oxygen under high oxygen pressures, due to the formation of the nonprotective highest oxide Nb2O5 as a main corrosion product.
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    URL: http://dx.doi.org/10.1007/BF01050800
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    The oxidation behavior of Fe-20Cr alloy foils in a synthetic exhaust-gas atmosphere (1996)
    Springer
    Oxidation of metals 46 (1996), S. 335-364 
    Details
    ISSN: 1573-4889
    Keywords: Fe−Cr ; oxidation ; exhaust gas ; oxide adherence ; titanium ; rare earths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation tests of rare-earth-modified and Ti-modified Fe−20Cr alloy foils, which are under consideration for catalytic converter supports, were performed in a synthetic exhaust-gas atmosphere (N2+H2O+CO2) between 900°C and 650°C. Between 900°C and 750°C, the rare earths had no effect on oxide growth rates while Ti increased growth rates. Oxide growth rates for the rareearth alloys at 800°C and 750°C are much lower than those found in the literature for oxidation of Fe−Cr alloys or pure Cr in O2-rich atmospheres. The slow growth rates for the rare-earth alloys agree with literature data for oxidation of stainless steels containing 〉20% Cr in wet atmospheres and are caused by growth of an oxide scale only one grain thick. At temperatures ≤700°C, Fe−20Cr alloys grow massive Fe oxides; however, this can be suppressed by adding rare earths or Ti. To ensure good oxide adherence, free sulfur must be eliminated in the alloy by tying it up with a reactive-element addition. Both Ti and the rare earths can be used to tie up S, but the rare earths are more effective. For converter applications, the optimum alloy composition may contain rare earths for good oxide adherence and a small amount of Ti to suppress growth of Fe-rich oxides.
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    URL: http://dx.doi.org/10.1007/BF01048635
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    Transient oxidation in Fe-Cr-Ni alloys: A Raman-scattering study (1996)
    Springer
    Oxidation of metals 46 (1996), S. 365-381 
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    ISSN: 1573-4889
    Keywords: oxidation ; steel ; Raman ; scale ; transient oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Using Raman scattering we have investigated the oxidation, in air, of the Fe-Cr-Ni stainless steels Fe-25Cr-20Ni, Fe-25Cr-20Ni-3Zr, and Fe-24Cr-3Zr (wt.%) as a function of temperature in the range 300 to 1000°C. The Raman technique is very sensitive to, and provides a clear identification of, the oxides Fe2O3 and Cr2O3. However, the technique is insensitive to NiO, FeO, and does not give a clear identification of spinels. The Fe−Cr−Ni alloys form chromia scales at temperatures greater than ∼800°C. At lower oxidation temperatures, transient phases are observed. With a 1-h heat treatment at 300°C, we observe the formation of an unidentified scale; we speculate that it is either amorphous or consists of disordered spinel(s). Near 400°C we begin to observe hematite (Fe2O3). The intensity of the Fe2O3 signal increases with temperature to ∼600°C and then decreases, being largely replaced by the signal from Cr2O3. The thickness of the Cr2O3 scale increases with temperature up to ∼1000°C above which spallation becomes apparent. Spinel phases also apparently persist in the scale to 1000°C.
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    URL: http://dx.doi.org/10.1007/BF01048636
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    The steady-State corrosion kinetics of two-phase binary alloys forming the most-stable oxide (1996)
    Springer
    Oxidation of metals 46 (1996), S. 383-398 
    Details
    ISSN: 1573-4889
    Keywords: high temperatures ; binary alloys ; two-phase alloys ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The steady-state kinetics in the high-temperature oxidation of binary A-B alloys containing a mixture of the conjugated solid solutions of B in A (alpha phase) and A in B (beta phase) with exclusive formation of the most-stable oxide BOv have been examined, assuming that the external scale grows on top of a subsurface layer of alpha phase. The results obtained are compared with the corresponding behavior of alloys which are single phase in the whole range of composition. Under identical values of all the parameters involved the concentration of B at the alloy-scale interface is smaller for two-phase than for single-phase alloys under the same concentration of B in the alloy as a result of the restricted flux of B through the alpha-phase layer. As a consequence of this, the two-phase alloys corrode more slowly than single-phase alloys and this difference increases as the solubility of B in the alpha phase decreases. Finally, the simultaneous formation of BOv both externally and as internal oxide is more likely for two-phase than for single-phase materials.
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    URL: http://dx.doi.org/10.1007/BF01048637
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    An analysis of the internal oxidation of binary M-Nb alloys under low oxygen pressures at 600–800°C (1996)
    Springer
    Oxidation of metals 46 (1996), S. 441-463 
    Details
    ISSN: 1573-4889
    Keywords: niobium alloys ; oxidation ; high temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The corrosion of M−Nb alloys based on iron, cobalt, and nickel and containing 15 and 30 wt% Nb has been studied at 600–800°C under low oxygen pressures (10−24 atm at 600°C and 10−20 atm at 700–800°C). Except for the Co−Nb and Ni−Nb alloys corroded at 800°C, which formed external scales of niobium oxides, corrosion under low O2 pressures produced an internal oxidation of niobium. This attack was much faster than expected on the basis of the classical theory. Furthermore, the distribution of the internal oxide in the alloys containing two metal phases was very close to that of the Nb-rich phase in the original alloys. These kinetic, microstructural, and thermodynamic aspects are examined by taking into account the effects of the limited solubility of niobium in the various base metals and of the two-phase nature of the alloys.
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    URL: http://dx.doi.org/10.1007/BF01048640
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    The effect of oxygen concentration on the oxidation of low-carbon steel in the temperature range 1000 to 1250°C (1996)
    Springer
    Oxidation of metals 46 (1996), S. 423-440 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; scaling ; surface temperature ; heat of reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper describes the oxidation behavior of low-carbon steel samples in binary gas mixtures of oxygen and nitrogen, at oxygen concentrations ranging between 1% and 15% and temperatures ranging between 1000 and 1250°C. Sample weight gains versus time were analyzed, along with measurements and calculations of sample heating rates due to exothermic heat of reaction at the sample surface. It was found that initial rates of oxidation depended on oxygen content in the gasmixture and that these reaction rates were linear up to oxide thicknesses of 0.4 to 0.5 mm. Calculations of linear oxidation rate constants based on equations for mass transport of oxygen in the gas mixture to the sample surface showed good agreement with those measured experimentally, indicating that the initial period of oxidation is controlled by the mass transport of oxygen to the reaction interface. The linear rate constants showed little dependency on temperature, an activation energy of approximately 17kJ/mole being obtained. Measurements of sample surface temperatures have shown that within this linear-oxidation regime, interfacial temperatures of the samples increase with increasing oxygen contents in the gas mixture, owing to exothermic heats of oxidation. Subsequent oxidation kinetics were found to be parabolic. Measured parabolic rates constants were in good agreement with previous investigations, with activation energy values of approximately 127kJ/mole.
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    URL: http://dx.doi.org/10.1007/BF01048639
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    Effect ofθ-alumina formation on the growth kinetics of alumina-forming superalloys (1996)
    Springer
    Oxidation of metals 46 (1996), S. 465-480 
    Details
    ISSN: 1573-4889
    Keywords: ODS Alloy ; oxidation ; SIMS ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Alumina-forming ODS superalloys are excellent oxidation-resistant materials. Their resistance relies upon the establishment of a stable, slow-growing, and adherent α-alumina. In the present investigation, these alloys exhibited unstable and relatively less adherent θ-alumina phase, which increased the oxidation rate in the transient stage and converted into α-alumina in the later part of the exposure. The oxide-growth process was found to depend upon various parameters such as temperature, time, and presence of an active elecment in the superalloy. Characterization carried out by XRD, SEM/EDAX, and AES on oxidized ODS and non-ODS alloys demonstrated a significant influence of the active element, Y, on the transformation of θ- to α-alumina. SIMS analysis of two-stage oxidation at 900°C for two different durations evidently showed that the change in the transport process is due to θ-to-α-alumina transformation. On the basis of these results, a new and consistent mechanism is proposed to explain the influence of θ-alumina and its transformation on growth kinetics and the effect of yttrium on the transformation leading to good scale adherence and oxidation resistance.
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    URL: http://dx.doi.org/10.1007/BF01048641
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    Shoot development and flowering in potato (Solanum tuberosum L.) (1996)
    Springer
    Potato research 39 (1996), S. 581-607 
    Details
    ISSN: 1871-4528
    Keywords: assimilate partitioning ; flower primordia survival ; flower production ; photoperiod ; stem production ; temperature ; time to flower primordia initiation ; tuber initiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The shoot system of potato is a configuration of stems with terminal inflorescences. In this review, shoot development is quantified in terms of stem production, while stem development is quantified in terms of leaf and flower primordia production per stem, which are functions of the rates and the durations of primordia initiation. The effect of the position of the stem in the shoot system on number of leaves and flowers per stem is also evaluated. Flowering of individual stems is described by the ‘time to flower primordia initiation’ (expressed in number of leaves produced) and ‘flower production’ (a function of the number and the development of flower primordia). At warmer temperatures and longer daylengths the number of leaves and flower primordia per stem, and the number of stems per shoot increase by prolonging stem production and primordia development. Temperature and photoperiod also affect flower primordia survival by altering assimilate production and partitioning. The photothermal response of the number of leaves per stem is small compared to the response of stem production; at higher temperatures, flower primordia survival becomes the principal factor determining flower production. The similarity of the signals leading to flower primordia initiation and tuberization, and the relation between shoot and tuber growth are discussed.
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    URL: http://dx.doi.org/10.1007/BF02358477
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    Acid-catalyzed formation of free radicals in the reaction of hydroperoxides with ketones (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 340-345 
    Details
    ISSN: 1573-9171
    Keywords: oxidation ; acid catalysis ; free radicals ; acetonitrile ; p-toluenesulfonic acid ; tert-butyl hydroperoxide ; cyclohexanone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of formation of free radicals in the cyclohexanone (CH)-tert-butylhydroperoxide (TBHP)-para-toluenesulfonic acid (PTSA) system in acetonitrile was studied. The stoichiometry of the reaction corresponds to the consumption of two TBHP molecules per ketone molecule, whereas the yield of free radicals is -20 % based on the TBHP reacted.
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    New heterocyclic system based on vinylsulfonylfluorobenzene and X-ray structural study of this compound (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 414-416 
    Details
    ISSN: 1573-9171
    Keywords: 1,2,4,5-tetrafluoro-3,6-bis(vinylthio)benzerne ; 1,2,4,5-tetrafluoro-3,6bis(vinylsulfonyl)benzene ; 5,6-difluorobenzo-[a,d]-bis(3,3′-dihydro-1,1′-sulfonylallyl-4,4′-perhydroazine) ; oxidation ; allylamine ; X-ray structural study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Oxidation of 1,2,4,5-tetrafluoro-3,6-bus (vinylthio)benzene (1) affords 1,2,4,5-tetra fluoro3,6-bis(vinylsulfonyl)benzene (2) in 65 % yield. The reaction of compound 2 with allylamine gives a new heterocyclic compound, 5,6-difluorobenzo-[a,d]-bis(3,3′-dihydro-l,l′-sulfonylallyl-4,4′-perhydroazine) (3). This compound is the product of nucleophilic addition at the vinylsulfonyl group and intramolecular replacement of fluorine atoms of the benzene ring. The structure of compound 3 has been established by X-ray structural study.
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    URL: http://dx.doi.org/10.1007/BF01433984
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    The influence of low-temperature oxidation of active carbons by nitric acid on their physicochemical properties (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1071-1077 
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    ISSN: 1573-9171
    Keywords: active carbons ; oxidation ; surface chemistry ; n-hexane ; water ; methanol ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of oxidation by nitric acid on the character of oxygen-containing functional surface groups and porous structure of active carbons is considered. Adsorption properties of the initial and oxidized carbons are studied using adsorption isotherms of vapor of n-hexane and polar substances (water and methanol).
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    Heat release kinetics in the reaction of decane with nitric acid (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1883-1888 
    Details
    ISSN: 1573-9171
    Keywords: decane ; nitric acid ; nitrogen dioxide ; oxidation ; kinetics ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the reaction of decane with nitric acid (25.07–75.53 %) at 57.8 to 119 °C in an acid-decane-gas triphasic system was studied. The main contribution to the rate of heat release is made by the oxidation of decane with nitrogen dioxide in the organic phase proceedingvia the mechanism of a degenerate branched-chain reaction. Nitration plays the role of a chain termination reaction. The acid phase is the source of NO2, whose content increases with oxidation. The equilibrium of the nitrogen dioxide distribution in the triphasic system was analyzed. The kinetic law of the reaction, the dependences of the reaction constants of the initial and catalytic stages on temperature and the acid phase composition were determined. The results allow one to calculate the rate of heat release in the decane-HNO3 system under any conditions of the process.
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    Phenazinee di-N-oxide radical cation and its reactions with hydrocarbons (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1889-1895 
    Details
    ISSN: 1573-9171
    Keywords: phenazine di-N-oxide ; radical cation ; hydrocarbons ; oxidation ; mechanism ; O2 effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The absorption spectra of phenazine di-N-oxide radical cation (OPO+·) in dichloromethane were recorded by the spectroelectrochemical method in the range from 300 to 700 nm. The reactions of the electrochemically generated OPO+· withpara-substituted toluenes, ethylbenzene, and cumene were studied. Using differential cyclic voltammetry, relative rate constants of reactions of OPO+· with substrates were determined; their correlations with σ+ para constants of substituents gives p = -2.7, which attests to the nonradical character of the reaction of OPO+· with RH. This conclusion is confirmed by the study of the effect of O2 on oxidation of ethylbenzene and cumene.
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    Interaction of diphenyl sulfide with sulfuryl chloride (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 2668-2669 
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    ISSN: 1573-9171
    Keywords: diphenyl sulfide ; sulfuryl chloride ; oxidation ; chlorination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction of diphenyl sulfide with sulfuryl chloride was studied. Depending on the reaction conditions, it occurs either as chlorination of the aromatic ring or as oxidation to give sulfoxide.
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    URL: http://dx.doi.org/10.1007/BF01431143
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    Formation of isomeric iodohydrins from terminal alkenes upon oxidation by a RuCl3-NaIO4 system (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 2813-2815 
    Details
    ISSN: 1573-9171
    Keywords: alkenes ; catalysis ; oxidation ; iodohydrins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract RuCl3-catalyzed periodate oxidation of alkenes affords isomeric iodohydrins.
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    URL: http://dx.doi.org/10.1007/BF01430649
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    Effects of pH and temperature on growth ofSaprolegnia diclina andS. parasitica isolated from various sources (1996)
    Springer
    Mycoscience 37 (1996), S. 385-390 
    Details
    ISSN: 1618-2545
    Keywords: pH ; Saprolegnia diclina ; Saprolegnia parasitica ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Saprolegnia diclina andS. parasitica isolated from three sources could germinate in strong acidic conditions. Growth ability correlated with the species of fungi rather than with the sources from which they were isolated.S.diclina isolates appeared to germinate at a pH condition as low as 3.5, whereasS. parasitica isolates could not germinate at below pH 3.8.S. parasitica isolates from visceral mycoses still showed good growth at 30°C, whereas other isolates did not. Also,S. parasitica isolates from visceral mycoses produced more abundant motile zoospores, and continued to do so for a longer period of time (28 d), thanS. parasitica isolates from external saprolegniasis andS. diclina isolates.
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    Effects of temperature, salinity and agitation on byssus thread formation of zebra musselDreissena polymorpha (1996)
    Springer
    Aquatic ecology 30 (1996), S. 187-195 
    Details
    ISSN: 1573-5125
    Keywords: Dreissena polymorpha ; byssus thread production ; temperature ; salinity ; agitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Byssus thread production ofD. polymorpha under different conditions of temperature, salinity and agitation were studied in the laboratory. The acclimation to salinity and temperature greatly affects the byssus production ofD. polymorpha. Byssus production of mussels was significantly reduced when temperature increased beyond 20°C and decreased below 10°C. Mussels with cut threads (for counting), produced a substantially increased number of threads. However, mussels with uncut byssus threads were comparatively more mobile. Byssus production of mussels did not vary significantly at salinities up to 3‰. Beyond this salinity byssus production was reduced significantly. Mussels increased their byssus production with increasing frequency of agitation.
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    URL: http://dx.doi.org/10.1007/BF02272238
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  • 90
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    In situ monitoring of chlorophyll fluorescence to assess the synergistic effect of low temperature and high irradiance stresses inSpirulina cultures grown outdoors in photobioreactors (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 283-291 
    Details
    ISSN: 1573-5176
    Keywords: fluorescence ; photoinhibition ; photosynthesis ; Spirulina ; photobioreactor ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A chlorophyll fluorescence technique was applied to anin situ study on the effects of low temperature and high light stresses onSpirulina cultures grown outdoors in controlled tubular photobioreactors at high (1.1 g L−1) and low (0.44 g L−1) biomass concentrations. Diurnal changes in PSII photochemistry (F v/F m) after 15 min of darkness, or in the light (dF/F′ m), and non-photochemical (qN) quenching were measured using a portable, pulse-amplitude-modulated fluorometer. The depression of theF v/F m ratio ofSpirulina cultures grown outdoors at 25°C (i.e. 10°C below optimum for growth) and 0.44 g L−1, reached 30% at the middle of the day. At the same time of the day thedF/F′ m ratio showed a reduction of up to 52%. The depression of bothF v/F m anddF/F′ m was lower in the cultures grown at 1.1 g L−1. Photoinhibition reduced the daily productivity of the culture grown at 0.44 g L−1 and 25°C by 33% with respect to that grown at 35°C. Changes in the growth yields of the cultures grown under different temperatures and growth rates correlate well with analogous changes in photon yield (dF/F′ m). Simple measurements of photochemical yield (F v/F m) can be used to test the physiological status ofSpirulina cultures. The results indicate that the saturating pulse fluorescence technique, when usedin situ, is a powerful tool for assessment of the photosynthetic characteristics of outdoor cultures ofSpirulina.
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    URL: http://dx.doi.org/10.1007/BF02178571
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  • 91
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    Outdoor cultivation ofArthrospira platensis during autumn and winter in temperate climates (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 293-301 
    Details
    ISSN: 1573-5176
    Keywords: Arthrospira platensis ; Spirulina ; tubular photobioreactors ; outdoor culture ; aeration rate ; cell density ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Arthrospira (Spirulina) platensis M2 was grown outdoors in 50-mm diameter tubular reactors under the climatic conditions of central Italy (Florence) from September to December 1995 and in March 1996. Except for September, the cultures temperature was regulated. Mean productivities of 0.83, 0.44 and 0.61 g dry wt L−1 d−1 were achieved in autumn (September–October), winter (November–December) and March, respectively. In autumn and winter, the photosynthetic efficiency of the cultures and the degree of correlation between productivity and solar irradiance were significantly greater than in summer. The effect of cell density and aeration rate on productivity was evaluated in September. The productivity of cultures operated at high supra-optimal population density was about 30% less at high aeration rate (1.0 LL−1 min−1), and 50% less at standard aeration rate (0.17 LL−1 min−1), than that of control cultures kept at optimal population density and standard aeration rate. The reduction of productivity in high-density cultures was due to lower daylight output rates and higher night biomass losses (the latter were particularly relevant under standard aeration conditions). The main factor limiting productivity in closed reactors during autumn was the night temperature. Heating the cultures during daylight hours on sunny days did not cause any significant increase of the yields, since under sunlight the unheated cultures also reached the optimal temperature for growth early in the morning. On cloudy days, the day-time temperature of the unheated cultures remained well below the optimum, however this had only a limited effect on productivity since algal growth was mainly light-limited.
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    URL: http://dx.doi.org/10.1007/BF02178572
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  • 92
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    Clinical and pharmacokinetic phase I trial of oral dimethylaminoetoposide (NK611) administered for 21 days every 35 days (1996)
    Springer
    Investigational new drugs 14 (1996), S. 379-386 
    Details
    ISSN: 1573-0646
    Keywords: NK611 ; dimethylaminoetoposide ; phase I ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have conducted a clinical and pharmacokinetic trial of the novel podophyllotoxin derivative NK611 administered orally for 21 consecutive days. The treatment was repeated every 35 days. Eighteen patients were included into the study, all of whom were eligible. Due to early progression of tumor disease in two patients, 16 patients were évaluable for toxicity [7 female, 9 male, median age 64 years (range: 44 to 73)]. Dose escalation steps were 5 mg/day [105 mg per cycle (pc)], 10 mg/day (210 mg pc), 12.5 mg/day (265 mg pc) and 15 mg/day (315 mg pc). A total of 37 courses was administered. Toxicity was evaluated using NCI-CTC criteria. Granulocytopenia was the main hematologic toxicity. Other hematologic toxicities were sporadic. Non-hematologic toxicities were mild and consisted of grade 1 nausea and grade 2 alopecia. Pharmacokinetic analyses were performed in six patients each treated with 10 mg/day and 12.5 mg per day, and in one patient treated with 15 mg/day. Using a two-compartment model, t1/2α ranged from 0.47 to 1.54 h and t1/2β from 2.0–11.6 h. Mean values for C max and AUC were 1.47 ± 0.331 μg/ml and 13.67±3.81 μg/ml·h. No objective tumor responses were observed. However, one patient with metastatic breast cancer had stable disease for twelve months. We conclude that the Maximum Tolerated Dose of NK611 administered daily for 21 consecutive days is 12.5 mg/day. The Dose-Limiting Toxicity is granulocytopenia. The recommended dose for further clinical Phase II studies is 10 mg/day.
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    URL: http://dx.doi.org/10.1007/BF00180814
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  • 93
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    Biodiversity and function of bacteria in the Southern Ocean (1996)
    Springer
    Biodiversity and conservation 5 (1996), S. 1505-1523 
    Details
    ISSN: 1572-9710
    Keywords: seasonal changes ; benthic bacteria ; bacterioplankton ; bacterial communities ; organic matter ; temperature ; Antarctic Oceans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: A short overview of the biodiversity of Antarctic marine bacteria is given with respect to morphology and metabolic activity. The importance of spatial and temporal variability is described. The physiological adaptation and ecological function of Antarctic marine bacterioplankton are discussed.
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    URL: http://dx.doi.org/10.1007/BF00051989
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  • 94
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    Interspecies Scaling of Bosentan, A New Endothelin Receptor Antagonist and Integration of in Vitro Data into Allometric Scaling (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 97-101 
    Details
    ISSN: 1573-904X
    Keywords: allometric scaling ; interspecies scaling ; pharmacokinetics ; clearance ; in vitro models ; bosentan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The goal of this study was to find a rational and reliable method of using animal data to predict the clearance of metabolised drugs in humans. Methods. One such approach is to use in vitro liver models (e.g. hepatocytes and microsomes) to determine the relative capacities of the various animal species and humans to metabolise the test compound. These data can then be combined with the in vivo clearances in animals, to calculate the in vivo clearance in humans using allometric scaling techniques. In this study, this approach was evaluated with a new endothelin receptor antagonist, bosentan, which is eliminated mainly through metabolism and is characterized by very large interspecies differences in clearance. Therefore, this compound provided a stringent test of our new extrapolation method for allometric scaling. Results. The results obtained with bosentan showed that adjusting the in vivo clearance in the different animal species for the relative rates of metabolism in vitro gave a far better prediction of human clearance than an empirical correcting factor (brain weight). Conclusions. This approach provided a more rational basis for predicting the clearance of metabolised compounds in humans.
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    URL: http://dx.doi.org/10.1023/A:1016037519116
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  • 95
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    Percutaneous Absorption of Ketoprofen from Different Anatomical Sites in Man (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 168-172 
    Details
    ISSN: 1573-904X
    Keywords: ketoprofen ; nonsteroidal anti-inflammatory agent ; topical application ; percutaneous absorption ; regional variation ; pharmacokinetics ; urinary excretion ; enantiomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of this study was to investigate the percutaneous absorption of ketoprofen applied topically to different anatomical sites on the body. Methods. The study design was a randomized, four-way crossover in 24 healthy male subjects. One gram of ketoprofen 3% gel (30 mg dose) was applied every six hours for 25 doses over a 100 cm2 of the back, arm, and knee. A 0.5 ml of ketoprofen solution (60 mg/ml) was applied to the back as a reference treatment. Plasma and urine samples were obtained for the assay of racemic ketoprofen and ketoprofen enantiomers (S and R), respectively. Results. The relative bioavailabilities of ketoprofen gel were 0.90 ± 0.50, 1.08 ± 0.63, and 0.74 ± 0.38 when applied to the back, arm, and knee, respectively. The plasma ketoprofen Cmax for gel applied to the back and arm were similar (p 〉 0.05) but Cmax was lower when applied to the knee (p 〈 0.05). The time to Cmax ranged from 2.7 to 4.0 hours and was similar for gel treatments on the back and arm, but longer for the knee treatment. The fraction of dose excreted in urine as total S and R enantiomers ranged from 5.41 to 9.10%. Conclusions. The percutaneous absorption of ketoprofen was similar when applied to either the back or arm but was lower when applied to the knee.
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    URL: http://dx.doi.org/10.1023/A:1016014308638
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    Pharmacokinetics of eltanolone following bolus injection and constant rate infusion (1996)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 24 (1996), S. 535-549 
    Details
    ISSN: 1573-8744
    Keywords: eltanolone ; pregnanolone ; Kabi 2213 ; context sensitive time ; anaesthesia ; healthy volunteers ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Disposition of intravenous anaesthetic eltanolone was studied when administered as a bolus injection (B) of 0.75 mg/kg and constant rate intravenous infusion at 2 mg/kg/hr (I2) and 3.5 mg/kg/hr (I3.5) for 2 hr in healthy male volunteers. Venous blood samples were collected for 12 hr and 20 hr following bolus injection and intravenous infusion, respectively. Serum eltanolone concentrations were determined by a specific gas chromatographic mass spectrometric assay. Using a nonlinear regression analysis, the individual data sets were best fitted by a three-compartment mamillary model with central elimination. Derived pharmacokinetic parameters expressed as median and 95% confidence intervals indicated an initial fast distribution with a half-life of 1.80 (0.23–5.47) min (B), 1.44 (0.97–2.06) min (I2) and 1.44 (0.95–2.39) min (I3.5), an intermediate phase with a half-life of 35.4 (28.7–45.2) min (B), 39.6 (31.0–47.9) min (I2) and 35.4 (33.3–44.9) min (I3.5) and a moderately short terminal phase with a half-life of 3.8 (2.7–5.9) hr (B), 5.0 (4.2–6.1) hr (I2) and 4.6 (4.0–4.8) hr (I3.5). The serum clearance after bolus injection was 1.37 (1.23–1.67) L/hr/kg and after infusion was 1.36 (1.25–1.52) L/hr/kg (I2) and 1.17 (1.11–1.31) L/hr/kg (I3.5). The pharmacokinetics of eltanolone appear to be linear over the dosage range studied. Pharmacokinetic parameters obtained after bolus injection were very much similar to the parameters obtained after infusion with the exception of t1/2β which was longer after the infusion (significant) and the volume of central compartment which was lower after infusion (not significant). Context sensitive times were estimated for a 30%, 50% and 80% drop in the concentration of eltanolone after different infusion times. A 30% drop in concentration is estimated to take about 2 to 3 min. A 50% drop in concentration, is estimated to take about 8 min when duration of infusion is 3 hr and reaches a value of about 10 min by a duration of infusion of 10 hr. A 80% drop in concentration is estimated to take about 55 min following an infusion of 1 hr and it reaches a value of 70–80 min following an infusion of 10 hr.
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    URL: http://dx.doi.org/10.1007/BF02353479
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    Bioequivalence assessment of etoposide phosphate and etoposide using pharmacodynamic and traditional pharmacokinetic parameters (1996)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 24 (1996), S. 313-325 
    Details
    ISSN: 1573-8744
    Keywords: etoposide ; etoposide phosphate ; bioequivalence ; pharmacokinetics ; pharmacodynamics ; humans ; cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The bioequivalence of etoposide phosphate, a prodrug of etoposide, to etoposide was assessed in a randomized, crossover study in 29 patients with histologically established solid tumors that had failed conventional treatment. Cohorts of patients received one treatment course each of etoposide and etoposide phosphate which consisted of a 100 mg/m2 per day etoposide equivalent dose infused iv over 1 hr on a Day 1 to 5 schedule of treatment. The second course was administered 21 days later or on recovery of blood cell counts. Plasma and urine samples were collected over 24 hr on Day 1 of each course and assayed for etoposide content by a validated HPLC/UV method. Resulting data were subjected to noncompartmental pharmacokinetic analysis. Hematology profiles were obtained by collecting blood samples prior to the first course and twice a week after each course. The pharmacodynamics and pharmacokinetics of etoposide were virtually identical after the two treatments. The point estimates (90% confidence intervals) for nadir WBC, granulocytes, hemoglobin, and platelets expressed as % decrease from the baseline, and for the pharmacokinetic parameters, Cmax, and AUC0-∞, after intravenous etoposide phosphate relative to etoposide were 100% (96%, 105%), 97% (91%, 103%), 95% (82%, 109%), 95% (84%, 106%), 107% (101%, 113%), and 113% (107%, 119%), respectively. Therefore, etoposide phosphate is bioequivalent to etoposide based on pharmacokinetic and pharmacodynamic assessments.
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    URL: http://dx.doi.org/10.1007/BF02353515
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  • 98
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    In vivo relationships between the cerebral pharmacokinetics and pharmacodynamics of thiopentone in sheep after short-term administration (1996)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 24 (1996), S. 1-18 
    Details
    ISSN: 1573-8744
    Keywords: thiopentone ; pharmacokinetics ; pharmacodynamics ; brain ; cerebral blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The cerebral kinetics and dynamics of thiopentone after infusions of 250, 500, and 750 mg over 2 min were examined in chronically instrumented sheep (6, 6, and 5 sheep per dose, respectively). The cerebral kinetics were studied by rapid sampling of arterial and dorsal sagittal sinus blood (afferent and efferent blood for the brain, respectively) for 40 min, and could be described by a single flow-limited compartment when arterial concentrations and cerebral blood flow were used as forcing input functions. The half-lives of equilibration between blood and the brain were estimated to be 0.67 (SEM=0.07), 0.57 (0.03) and 0.74 (0.05) min for the 250-, 500- and 750-mg doses, respectively, showing that the cerebral concentrations of thiopentone rapidly equilibrate with the afferent blood concentration. Simultaneous pharmacodynamic measurements included cerebral blood flow via a Doppler flowmeter on the sagittal sinus, and an index of the depth of anesthesia based on an algesimetry method. Thiopentone transiently reduced cerebral blood flow to 82 (SEM=3), 80% (7), and 74% (10) of baseline for the 250−, 500−, and 750-mg doses, respectively, and failure to account for drug-induced changes in cerebral bloof flow in the model overestimated the apparent volume of the brain by 12% for the 500-mg dose. For the 500-mg dose, the changes in cerebral blood flow could be accounted for by an effect compartment with a half-life of 0.82 min for arterial blood, and 0.00 min for sagittal sinus blood, showing the effluent brain concentrations were in equilibrium with this drug effect. The time course of the depth of anesthesia for the 250-mg dose could be accounted for by an effect compartment with a half-life of 1.33 min for arterial blood, and 0.41 min for sagittal sinus blood. Thus, the rate of equilibration between blood and brain could not account for all of this delay. It is concluded that after short-term administration thiopentone equilibrated rapidly with the brain, and that this is consistent with the observation that the magnitude of its clinically relevant effects closely follow the time course of the arterial blood concentrations.
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    URL: http://dx.doi.org/10.1007/BF02353508
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    Pharmacokinetics and pharmacodynamics of azosemide after intravenous and oral administration to rats: Absorption from various GI segments (1996)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 24 (1996), S. 551-568 
    Details
    ISSN: 1573-8744
    Keywords: azosemide ; pharmacokinetics ; pharmacodynamics ; multiple peaks ; absorption from various segments of GI tract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Azosemide, 5, 10, 20, and 30 mg/kg, was administered both intravenously and orally to determine the pharmacokinetics and pharmacodynamics of azosemide in rats (n=7–12). The absorption of azosemide from various segments of GI tract and the reasons for the appearance of multiple peaks in plasma concentrations of azosemide after oral administration were also investigated. After intravenous (iv) dose, the pharmacokinetic parameters of azosemide such ast 1/2, MRT, VSS, CL, CLR, and CLNR were found to be dose-dependent in the dose ranges studied. The percentages of the iv dose excreted in 8-hr urine as azosemide, MI (a metabolite of azosemide), glucuronide of azosemide, and glucuronide of MI—expressed in terms of azosemide—were also dose-dependent in the dose ranges studied. The data above suggest saturable metabolism of azosemide in rats. The measurements taken after the iv administrations such as the 8 hr urine output, the total amount of sodium and chloride excreted in 8-hr urine per 100 g body weight, and diuretic, natriuretic, kaluretic, and chloruretic efficiencies were also shown to be dose-dependent. However, the total amount of potassium excreted in 8-hr urine per 100 g body weight was dose-independent. Similar dose-dependency was also observed following oral administration. Azosemide was absorbed from all regions of GI tract studied and approximately 93.5, 79.1, 86.1, and 71.5% of the doses (5, 10, 20, and 30 mg/kg, respectively) were absorbed between 1 and 24 hr after oral administration. The appearance of multiple peaks after oral administration is suspected to be due mainly to the gastric emptying pattern. The percentages of azosemide absorbed from the GI tract as unchanged azosemide for up to 24 hr after oral doses of 5, 10, 20, and 30 mg/kg were significantly different with doses (decreased with increasing doses), suggesting that the problem of azosemide precipitating in acidic gastric juices or dissolution may have at least partially influenced the absorption of azosemide after oral administration.
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    URL: http://dx.doi.org/10.1007/BF02353480
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  • 100
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    Essential of the environmental control of insect seasonality as reference points for comparative studies in other invertebrates (1996)
    Springer
    Hydrobiologia 320 (1996), S. 123-130 
    Details
    ISSN: 1573-5117
    Keywords: insects ; seasonality ; photoperiod ; temperature ; developmental reactions ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A great body of knowledge of photoperiodic and other developmental reactions, governing seasonality in insects, may be helpful for similar investigations which are or will be conducted with other animal groups. The following principles, based on a recent hypothesis, seem the most significant to be tested in comparative studies. (1) On the level of the photoperiodic clock only quantitative perception of photoperiod takes place. (2) The following, presumably neuroendocrine, ‘managing’ level of the mechanism discriminates between long and short days, determines the type of the response, and integrates photoperiodic and temperature reactions. (3) A working hypothesis, to be tested with both insects and other invertebrates, is that the ‘managing’ mechanism described in the model of photoperiodic and temperature control of development may have several sensory inputs and, therefore, plays a central role in governing developmental reactions to different environmental cues.
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    URL: http://dx.doi.org/10.1007/BF00016813
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