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  • Scanning electron microscopy  (77)
  • Chromatographie, Gas  (67)
  • bioavailability  (65)
  • Springer  (209)
  • Periodicals Archive Online (PAO)
  • 1975-1979  (209)
Collection
Keywords
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  • Springer  (209)
  • Periodicals Archive Online (PAO)
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 181 (1977), S. 31-40 
    ISSN: 1432-041X
    Keywords: Cell migration ; Mesoderm ; Gastrulation ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At the end of gastrulation, the lateral mesoderm of amphibian embryos migrates ventrally between the ectoderm and the endoderm. The present study is an examination of the morphology of the leading cells of the mesodermal sheet and of the substratum over which they move (the inner surface of the ectoderm). The cells of the leading edge of the mesoderm are generally round, with very short and narrow flattened projections in the forward direction. These projections do not have a “ruffled” morphology, regardless of whether fixation is carried out before or after the ectoderm and mesoderm are dissected away from the endoderm. The inner surface of the ectoderm is covered with fine (450–500A) filamentous extracellular material and the ectoderm cells sometimes extend cytoplasmic processes (approx. 0.1 μ wide) onto the leading surface of the mesoderm or onto adjacent ectoderm cells. These studies indicate that the morphology of cell migration in amphibians is closer to that seen inFundulus than to that characteristic of chick or mammalian cells.
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  • 2
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    Calcified tissue international 27 (1979), S. 33-40 
    ISSN: 1432-0827
    Keywords: Chick embryo ; Bone ; Organ culture ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The study describes the ultrastructure of the mineralized portion of chick tibiae from 10 days in ovo to 2 days post-hatch. At 10 days a single mineralized cylinder surrounds the diaphysis. On its outer surface columnar trabeculae join to form ridges parallel to the long axis of the bone. These ridges are covered by another cylinder and form the haversian canals. At 11 days vascular invasion of the marrow cavity occurs and resorption of the endosteal surface begins. This type of periosteal deposition and endosteal resorption is repeated during and subsequent to embryonic development. The mineralized portion of 10-day chick tibiae cultured for 2 days in modified BGJ medium was compared with 10-, 11-, and 12-day tibiae in ovo. Cultured tibiae were similar in length and calcium content to 11-day tibiae in ovo. The form of mineral deposited in ovo and in culture was the same, namely, aggregates of spherical mineral clusters. Differences in culture included the following: (a) few concentric cylinders were deposited as compared with tibiae in ovo; (b) trabeculae were not arranged in rows and ridges in culture; (c) osteocytic lacunae were restricted to bases of trabeculae rather than uniformly distributed as in ovo; and (d) the endosteal surface of tibiae in culture appeared etched.
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  • 3
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    Calcified tissue international 26 (1978), S. 237-241 
    ISSN: 1432-0827
    Keywords: Epiphyseal chondrocytes ; Freezefracture ; Scanning electron microscopy ; Cell processes ; Membrane particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Chondrocytes in epiphyseal cartilage were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) using freeze-fracture techniques. Freeze-fracture replicas showed large numbers of fingerlike, 0.11–0.15 μm diameter, projections from the chondrocyte surface, with numerous 95–180 Å diameter intramembranous particles associated with both the cell membrane surface and these projections. With SEM, these cytoplasmic projections were also obvious, but appeared collapsed into clusters of globular-shaped projections on the surface of the chondrocytes. With freeze-fracture techniques, in which shrinkage artifacts were essentially eliminated, the cytoplasmic projections were often seen in intimate contact with the extracapsular matrix. However, with chondrocytes prepared by both SEM and conventional TEM, there was evidence of shrinkage, the cytoplasmic projections having little contact with the extracapsular matrix. These findings show that the cytoplasmic processes are not artifacts of tissue processing and provide morphological evidence in support of the hypothesis that matrix vesicles are of cellular origin.
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  • 4
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    Calcified tissue international 25 (1978), S. 75-83 
    ISSN: 1432-0827
    Keywords: Rat ; Fluorosis ; Enamel ; Scanning electron microscopy ; Low temperature incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Sixteen 58-day-old male rats of Wistar strain, with a mean body weight of 179 g, were divided into two equal groups. Each group of eight animals was maintained for 70 days on drinking water, ad lib., containing no fluorine (control group) and 100 ppm of fluorine (experimental group). All specimens examined were obtained from the incisal portions of the incisors. The following types of enamel specimens were prepared for scanning electron microscopy: (1) acid-etched specimens; (2) acid-etched specimens followed by low temperature microincineration; and (3) fractured specimens. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core and interprismatic region was lower than that of control animals. The organic substances appeared to increase in these regions. These changes were prominent in the outer and middle enamel layers. Such changes following fluoride administration appear to indicate an inhibition of enamel maturation, that is, an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal.
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  • 5
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    Planta 146 (1979), S. 203-210 
    ISSN: 1432-2048
    Keywords: Cellulose ; Microfibrils ; Negative staining ; Nicotiana ; Protoplasts ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study has been made of the wall fibrils produced by tobacco protoplasts, using scanning electron microscopy in conjunction with negative staining. It has been shown that the fibres seen in scanning electron microscopy correspond to aggregates of microfibrils. These aggregates are only visible where they are lifted clear of the protoplast surface. Negative staining of fixed protoplasts shows that the aggregation of microfibrils into the fibres visible in scanning electron microscopy is probably produced by air-drying. Gentle disruption of microfibrils produces both random broken fragments and bundles of short pieces of fibrillar material about 60 nm in length. This material is present in undisrupted young walls, but not in undisrupted older walls. The microfibrils in young walls seem much more fragile and liable to breakage than those in older walls. These results are discussed in terms of the interpretation of scanning electron microscope images and the mechanism of cellulose microfibril formation by higher plants.
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  • 6
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    European journal of clinical pharmacology 8 (1975), S. 293-299 
    ISSN: 1432-1041
    Keywords: Rifampicin ; p-aminosalicylic acid ; bentonite ; drug interaction ; bioavailability ; drug adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability (plasma concentrations, AUC and urinary excretion) of an oral solution of rifampicin was investigated in six healthy volunteers. Simultaneous administration of PAS granules produced a significant decrease in the absorption of RMP, whereas Na-PAS tablets had no effect. This indicated that the dosage form of the granules and not PAS itself was responsible for the interaction, and that the dissolution of RMP was not involved. The interaction could be reproduced by giving dummy granules that contained the same excipients but no PAS. The disintegration and dissolution of PAS granulesin vitro correlated well with the disappearance of RMP from the solution. The major excipient of the granules, bentonite (a mineral closely related to kaolin), was found to adsorb rifampicin rapidly and strongly.
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  • 7
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    European journal of clinical pharmacology 8 (1975), S. 365-370 
    ISSN: 1432-1041
    Keywords: Particle size ; bioavailability ; digoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of digoxin in three tablets prepared from materials with different particle sizes was measured in healthy volunteers in a cross-over study using an alcoholic solution of digoxin as a reference standard. Its bioavailability in tablets with particle sizes of 7 µ or 13 µ was 78–97% of that of digoxin in solution. The tablet with largest particle size (102 µ) showed markedly lower bioavailability than the reference solution, namely 39%. It is obvious that particle size is an important determinant of the dissolution rate and bioavailability of digoxin.
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  • 8
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    European journal of clinical pharmacology 9 (1975), S. 209-212 
    ISSN: 1432-1041
    Keywords: Anticonvulsants ; phenytoin ; diphenylhydantoin ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma phenytoin levels were measured in 60 patients under steady-state conditions for a period of six weeks. During the trial, the preparation of phenytoin was changed from Phenytoin BP (Regent) to Epanutin Infatabs. A significant increase in plasma phenytoin levels following the change of tablet was matched by a decrease in the number of seizures.
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  • 9
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    European journal of clinical pharmacology 9 (1975), S. 213-218 
    ISSN: 1432-1041
    Keywords: Phenytoin ; diphenylhydantoin ; anticonvulsants ; bioavailability ; drug absorption ; generic inequivalence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In order to evaluate the bioavailability of four different brands of phenytoin (diphenylhydantoin, DPH) tablets single doses of 600 mg DPH in acid form were given to six volunteers in a cross-over study. A micronized DPH-acid suspension was used as the reference standard. Significant differences between various products were found. The areas under the serum DPH concentration-time curves (AUC) were 26, 59, 68 and 90 per cent of the AUC of the DPH suspension. The peak serum DPH concentrations using the different tablets were 24, 54, 55 and 80 per cent of the peak value of the DPH suspension. It is likely that the differences in bio-availability of the DPH tablets are of clinical significance.
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  • 10
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    European journal of clinical pharmacology 9 (1976), S. 315-317 
    ISSN: 1432-1041
    Keywords: Tolamolol ; bioavailability ; maximum exercise tachycardia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Bioavailability of capsule and tablet formulations of tolamolol were compared by measuring plasma concentration of tolamolol and reduction in maximum exercise heart rate over a period of twelve hours in eight healthy subjects in a two-way cross-over study. Tolamol was absorbed more rapidly from capsules than from tablets; this did not result in any significant difference in the reduction in maximum exercise heart rate between the two formulations. There was no significant difference between area under curve of reduction in exercise tachycardia and area under curve of plasma concentration of tolamolol for the two formulations. Reduction in maximum exercise heart rate was related to logarithm of plasma concentration of tolamolol between two and twelve hours after both formulations.
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  • 11
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    European journal of clinical pharmacology 9 (1976), S. 373-379 
    ISSN: 1432-1041
    Keywords: Methyldigoxin ; repetitive doses ; bioavailability ; deep compartments ; oral and i.v. dose ; volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To obtain true half lives, glycoside elimination from six healthy subjects was studied for 14 days after multiple intravenous doses or oral administration of a daily maintenance dose of β-methyldigoxin 0.3 mg. After oral or intravenous administration of β-methyldigoxin ceased, the plasma concentrations declined from the 14th to the 16th days with a half life of 1.7 days. From the 16th to the 20th day a change from a shorter to a longer half life of 2.8 and 2.9 days was observed. Similar half lives were found in urine: after the last dose the initial slope from the 14th to the 16th day had a half life of 1.8 days, and the terminal slope had one of 3.2 days. The results indicate release of the glycoside from slowly equilibrating tissues.
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  • 12
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    European journal of clinical pharmacology 8 (1975), S. 371-376 
    ISSN: 1432-1041
    Keywords: Digoxin ; bioavailability ; plasma levels ; cumulative urinary excretion ; particle size ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Various brands of digoxin tablets, and even different batches of one brand, may differ greatly in bioavailability. Digoxin-Sandoz® tablets have been compared with Lanoxin® manufactured between 1969 and 1972 and after May 1972. Comparisons were also made between and within batches of Digoxin-Sandoz tablets. Three separate cross-over studies were conducted involving a total of 20 volunteers. Digoxin-Sandoz tablets were shown to have a constant bioavailability and to produce plasma concentrations very similar to “new” Lanoxin. Storage for 2 years of one batch of Digoxin-Sandoz did not alter the bioavailability. Particle size was shown to influence bioavailability. Care should be exercised when plasma data alone are interpreted as an index of bioavailability. Measures of bioavailability based on plasma data obtained up to 6 h after administration differed from those based on cumulative urinary excretion data (in this study by a factor of about 2), which can lead to the belief that a difference in bioavailability is much greater than is actually the case. Data from cumulative urinary excretion, collected over a sufficiently long period of time, are likely to be the most reliable method for determining the bioavailability of a substance such as digoxin.
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  • 13
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    European journal of clinical pharmacology 16 (1979), S. 211-215 
    ISSN: 1432-1041
    Keywords: fluoride ; bioavailability ; calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of milk products on the gastrointestinal absorption of fluoride from sodium fluoride tablets was studied in five healthy subjects. Two different diets were tested: (1) 250 ml standardized milk (3% fat) and (2) 500 ml of milk, 3 pieces of white bread with cheese and 150 ml of yoghurt. The 100% bioavailability of sodium fluoride tablets during fasting was greatly decreased by coadministration of milk products: with Diet 1 the absolute bioavailability calculated from combined plasma and urine data was in the range 50–79% and with Diet 2 it ranged from 50–71%. It is suggested that the decreased bioavailability produced by dairy products should be taken into account when establishing fluoride dosage regimens for prophylaxis of caries.
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  • 14
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    European journal of clinical pharmacology 10 (1976), S. 231-236 
    ISSN: 1432-1041
    Keywords: Digoxin ; beta-methyl-digoxin ; capsules ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The intestinal absorption and urinary elimination rate of total cardioactive material was compared following digoxin and beta-methyldigoxin (BMD) administration to twelve healthy volunteers. Significantly more injected digoxin was recovered in urine. Urinary clearance was more rapid for digoxin, mean half-lives of elimination being 35 hours for digoxin and 40 hours for BMD. Calculated percentage intestinal absorption was lowest for digoxin tablets with a dissolution rate of 77% in one hour, intermediate for BMD tablets, and maximal for an experimental soft gelatin formulation of digoxin in solution. Respective mean values were 75%, 87% and 97%. Similar steady state plasma concentrations followed twice daily ingestion of the 0.25 mg digoxin tablets and 0.20 mg BMD tablets. Mean peak plasma concentration and percentage urinary recovery of ingested dose were higher during continued BMD administration. Between-subject variation in absorption was higher for the digoxin tablets. The comparative intestinal absorption of BMD and digoxin depends upon the formulation. Digoxin is virtually completely absorbed from a solution encapsulated in soft gelatin. Relatively more BMD is eliminated by nonrenal routes.
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  • 15
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    European journal of clinical pharmacology 10 (1976), S. 251-256 
    ISSN: 1432-1041
    Keywords: Sisomicin ; pharmacokinetics ; bioavailability ; two-compartment analysis ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of sisomicin, a new single component aminoglycoside antibiotic related to gentamicin c1a, were determined in four healthy volunteers after intravenous and intramuscular administration of a 1 mg/kg dose. The elimination profile of this antibiotic follows two-compartment model kinetics after I.V. administration. The fast (α) and slow (β) disposition rate constants averaged 0.072 and 0.004 min−1, respectively. The volume of distribution at the steady-state averaged 0.185 liters/kg which approximately corresponds to the volume of extracellular space. The physiological availability of an intramuscular dose appeared to be complete. A method of administration adapted to the kinetic properties of the drug is proposed.
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  • 16
    ISSN: 1432-1041
    Keywords: Cefoxitin ; lidocaine ; intramuscular ; bioavailability ; pain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The use of lidocaine HCl solution at concentrations of 0.5 and 1.0% to reconstitute sodium cefoxitin relieves the pain associated with intramuscular injections of the antibiotic. Cefoxitin absorption by the intramuscular route is initially rapid and is virtually complete. Peak serum concentrations, corresponding to about one-half those of a comparable intravenous infusion, are achieved in 30 min. Continuing absorption tends to maintain higher serum concentrations for longer times. Renal clearance and serum half-life of cefoxitin do not appear to be affected by lidocaine at its effective anaesthetic concentrations.
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  • 17
    ISSN: 1432-1041
    Keywords: p-Chlorophenoxyisobutyric acid ; clofibrate ; steady-state plasma concentrations ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma concentrations and bioavailability of clofibrinic acid have been estimated under conditions approaching the steady-state during a ten-day period of administration as clofibrate or as a calcium clofibrinate-carbonate combination (1:1 w/w) at a dosage interval of 12 h. Formulation — related differences in bioavailability were not significant, and the 95% confidence limits of these differences were within −2% to +8% of the mean for the reference formulation of clofibrate. The mean steadystate plasma concentrations of clofibrinic acid measured on the tenth day of dosing were 116 µg/ml±22 S.D. and 119 µg/ml±23 S.D. after administration of 885 mg as clofibrate and the calcium clofibrinate-carbonate combination respectively. The peaks of mean plasma concentrations were 70 µg/ml±15 S.D., 119 µg/ml±32 S.D. and 131 µg/ml±26 S.D. on the first, fifth and tenth day of dosing with clofibrate, and 62 µg/ml±13 S.D., 127 µg/ml±S.D. and 143 µg/ml±25 S.D. on the corresponding days of dosing with the calcium clofibrinate-carbonate combination. After the last dose on the tenth day of dosing, the mean apparent half-lives of elimination of clofibrinic acid from plasma were 24.2 h±4.4 S.D. and 25.5 h±3.2 S.D. after administration of clofibrate and the calcium clofibrinate-carbonate combination respectively.
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  • 18
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    European journal of clinical pharmacology 13 (1978), S. 125-128 
    ISSN: 1432-1041
    Keywords: bioavailability ; diuretics ; gastrointestinal absorption ; hydrochlorothiazide ; thiazides ; food effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Hydrochlorothiazide (hct) 75 mg was administered orally to eight healthy volunteers without (Study I) or together with a standardized meal (Study II), and plasma and urine concentrations of hct were analyzed by GLC. The plasma levels of hct were higher initially when the tablets were taken on an empty stomach, but after 5 h they were higher in Study II. There was no difference between the two studies in the area under plasma concentration time curves. The urinary recovery of hct totalled 55.6±4.9 mg when the drug was given with food and 47.4±6.0 when it was taken on an empty stomach. The difference is significant (p〈0.01). As the urinary recovery represents the uptake of hct, it appears that the gastrointestinal absorption of hct is enhanced when the drug is given with food.
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  • 19
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    European journal of clinical pharmacology 10 (1976), S. 257-262 
    ISSN: 1432-1041
    Keywords: Anti-inflammatory and analgesic drug ; indoprofen ; pharmacokinetics ; bioavailability ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a pharmacokinetic study of the new analgesic and anti-inflammatory drug indoprofen, plasma levels and urinary excretion were determined in four healthy volunteers after 100 mg and 200 mg iv, and after 100 mg (capsules) and 200 mg (tablets) oral doses. After iv administration, the mean biological half-life (t1/2 β) was about 2 h (range 1.4 to 3.2 h). The apparent volume of distribution Vdβ ranged between 11 to 17 % of body weight, indicating its limited extravascular distribution. Most of the drug was excreted in urine as glucuronide and a smaller proportion as unchanged indoprofen: the 24 h urinary excretion of these compounds accounted for 67 to 95 % of an iv dose. Peak plasma levels occurred between 30 and 120 minutes after oral administration of 100 mg as capsules or 200 mg as tablets. The mean biological half-life was about 2 h, as after iv administration. The bioavailability of oral doses was assessed using both plasma levels and urinary excretion data. The absorption of capsules and tablets was practically complete, that of the former being faster.
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  • 20
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    European journal of clinical pharmacology 10 (1976), S. 101-108 
    ISSN: 1432-1041
    Keywords: Cardiac glycosides ; methyl proscillaridin ; plasma concentrations ; electrocardiogram ; bioavailability ; 86Rb-erythrocyte assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The aim of this study was to obtain data about the pharmacological properties of a new glycoside derivative in man. Plasma concentrations and ECG parameters were measured after oral and intravenous administration of a single dose of 1.2 mg methyl proscillaridin in 16 healthy volunteers, using a strictly randomized, two-period change-over design. Glycoside concentrations were measured using a modified86Rb-erythrocyte-assay. QT-duration, corrected for frequency (QTc), was the principal variable measured in the ECG. By either route, there was a maximum plasma level after 1 hour, which had decreased to a minimum at 3 hours, followed by a second peak at 4 to 10 hours (orally〉iv). From 10 to 72 hours the concentrations decreased with a median t 1/2 of 23.3 hours (iv) and 33.0 hours (orally). Comparison of the ratio of plasma concentrations following oral and iv administration resulted in a bioavailability of 69 % using the 48 hour plasma levels, and 59 % using the areas under the concentration-time curves. The mean QTc was maximally shortened to 28 msec at 1 hour after iv and to 19 msec at 10 hours after the oral dose. A distinct similarity between time-concentration and time-QTc curves was seen after the initial distribution phase, both after oral and intravenous administration. The new derivative shows a rapid elimination. Its bioavailability is reasonably high.
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  • 21
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    European journal of clinical pharmacology 16 (1979), S. 417-421 
    ISSN: 1432-1041
    Keywords: theophylline ; aminophylline ; bioavailability ; rapidly dissolving tablet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of a rapidly dissolving tablet of theophylline and three brands of standard aminophylline tablets was estimated in a four way cross-over study involving 8 healthy adult volunteers. The relative extent of bioavailability as assessed by the measurement of the total area under the plasma concentration time curves showed no difference between the products (P〉0.05). Computed estimates of the rate of drug absorption were similar for all 4 products tested. The results indicate that the rapidly dissolving tablet offers no advantage in respect to rate and extent of absorption over conventional aminophylline tablets.
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  • 22
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    European journal of clinical pharmacology 12 (1977), S. 69-72 
    ISSN: 1432-1041
    Keywords: Metronidazole ; serum concentration ; bioavailability ; food intake ; healthy subjects ; Crohn's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The possible influence of food intake on the bioavailability of metronidazole was examined in ten healthy volunteers by administration of a single dose of metronidazole on an empty stomach, and with a standardized breakfast. Food intake did not significantly alter the bioavailability of metronidazole. The interindividual variation in bioavailability appeared to be slight. In nine patients with Crohn's disease, the absorption of metronidazole appeared to be reduced and to be more variable than in healthy subjects. In both groups there was a clear relationship between the amount absorbed and dose/kg body weight. Thus, from the pharmacokinetic point of view, metronidazole can safely be given either with or between meals. The dose should be related to body weight.
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  • 23
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    European journal of clinical pharmacology 12 (1977), S. 285-290 
    ISSN: 1432-1041
    Keywords: Phenytoin acid ; phenytoin calcium ; bioavailability ; inequivalence of generics ; normal subjects ; volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Serum phenytoin concentrations have been studied in epileptic patients and healthy subjects taking tablets of phenytoin calcium (Desitin), A, phenytoin acid (Desitin), B, and phenytoin acid (Nordmark), C. Retrospective data and prospective investigation of hospitalized patients on long-term phenytoin treatment showed that significantly higher serum concentrations of phenytoin were produced by the phenytoin acid preparations B and C than by the phenytoin calcium preparation A. In a cross over study six volunteers received 200 mg/day of preparations A, B, and C for three weeks. In this study, too, higher phenytoin serum concentrations were produced by B and C than by A, although the differences were not statistically significant. The reasons for the discrepancies between the studies in healthy and epileptic subjects are discussed.
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  • 24
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    European journal of clinical pharmacology 12 (1977), S. 383-386 
    ISSN: 1432-1041
    Keywords: Benzodiazepine ; temazepam ; pharmacokinetics ; bioavailability ; hard and soft gelatine capsules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma levels of temazepam were determined in healthy subjects after single oral administration of soft and hard gelatin capsules, and after 7 consecutive night-time doses in soft capsules. Absorption from soft gelatin capsules was significantly faster and produced earlier and higher peak plasma levels. The two pharmaceutical forms did not show any significant difference in relative availability. The apparent half-life of temazepam after night-time administration was significantly shorter than after morning administration, but no change in half-life was observed between the first and seventh night-time doses.
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  • 25
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    European journal of clinical pharmacology 14 (1978), S. 253-259 
    ISSN: 1432-1041
    Keywords: Pseudoephedrine ; side effects ; bioavailability ; multiple oral dosing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Dose tolerance and pharmacokinetic studies of pseudoephedrine sustained action capsules were performed in thirty-three adult male subjects who received either 120 mg or 150 mg capsules every twelve hours for seven consecutive days in a double-blind parallel design study. Although only one subject in the 150 mg group was discontinued prematurely from this study, a large number of side effects typical of CNS stimulation were seen. A placebo effect might account for a portion of these complaints, however symtoms evaluated as being due to drug were significantly more severe and persistent in the 150 mg group. Pulse rates showed a persistent and significant increase while systolic and diastolic blood pressure fell from the baseline values in both groups. A pharmacokinetic analysis of the pseudoephedrine plasma concentration-time data provided estimates of half-life and the volume of distribution/availability ratio. The values obtained were in good agreement with values reported by others. Half-life was not influenced by urine pH probably as a result of the narrow range of urine pHs observed in the subjects. Calculations of relative bioavailability suggest that the 120 mg capsule formulation has a 30% greater bioavailability compared to the 150 mg capsule.
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  • 26
    ISSN: 1432-1041
    Keywords: chlorthalidone ; pharmacokinetics ; oral and i.v. doses ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Seven normal human volunteers each received a constant-rate infusion of chlorthalidone for 2 h, and the same (commonly 50 mg) single oral dose on separate occasions. The concentration of unchanged chlorthalidone was analyzed over a 100 to 220 h period in plasma, red blood cells, urine and faeces after both dosage forms. A three compartment model was required to describe the intravenous plasma concentrations in five of the subjects. A two compartment model sufficed to account for the decay of the oral plasma concentrations in all seven subjects. The mean plasma t1/2 after i.v. dosing was 36.5 h (±10.5 SD), and the mean plasma t1/2 after oral doses was 44.1 h (±9.6 SD). The mean red blood cell concentration t1/2 after i.v. doses was 46.4 h (±9.9 SD), and the mean red blood cell t1/2 after the oral doses was 52.7 h (±9.0 SD). The shorter i.v. half-live was not equally manifest in all subjects, being mainly apparent in three of them. In all cases the urinary excretion rate plots were parallel to the plasma concentration curves. As the faster decay after i.v. administration was not accompanied by increased renal clearance, the difference must have been due to non-renal mechanism. The mean total of 65.4 (±8.6 SD) % of the intravenous dose was excreted in urine over infinite time, whereas the mean total excretion after the oral dose was 43.8 (±8.5 SD) %. Faecal excretion ranged from 1.3–8.5% of dose in the i.v. study to 17.5–31.2% of dose in the oral study. The sum of the amounts present in urine plus faeces pointed strongly to an important metabolic route of elimination of chlorthalidone. Bioavailability estimates (F) from three sets of data were — a mean F of 0.61 from plasma concentrations, 0.67 from urinary excretion measurements and 0.72 from the erythrocyte concentrations. Simulations with a non-linear model indicated lesser validity of the estimate from erythrocyte concentrations. It was concluded that the average of plasma and urine data, F=0.64, yielded the best estimate of the oral availability of chlorthalidone 50 mg in man.
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  • 27
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    European journal of clinical pharmacology 16 (1979), S. 31-38 
    ISSN: 1432-1041
    Keywords: bezafibrate ; hyperlipoproteinemia ; bioavailability ; pharmacokinetics ; GC-MS
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The disposition kinetics of bezafibrate, a newly developed drug of great lipid-lowering potency, were investigated in normal male subjects. Five male volunteers received14C-labelled bezafibrate orally in solution, and a further 10 were given the same dose (300 mg) of un-labelled drug as tablets. The concentration of bezafibrate in serum and urine from the latter was determined by GC, and in the former total radioactivity in serum, urine and feces was followed for 48 h, and urinary excretion products were analysed by TLC and GC-MS. Rapid absorption from the gastrointestinal tract led to peak serum levels 30 min and 2 h after administration of solution and tablets, respectively. Since approximately 95% of the administered14C-bezafibrate was excreted in urine within 48 h, and almost all the remainder was detected in feces, absorption can be regarded as complete after administration in solution. The relative optimal bioavailability from the tablets was also complete, since in both cases approximately 50% of the administered dose was detected as unchanged bezafibrate in urine within 24 h by GC in the tablet study, and by TLC in the solution study. Of the decomposition products, more than 20% of the dose was present as glucuronides and the remainder consisted of several more polar compounds, one of which was identified as a hydroxyderivative of bezafibrate. Since the apparent halflife of bezafibrate in serum was 2.1 h, this new drug possesses favourable pharmacokinetic features: rapid and complete absorption, even from tablets, combined with a conveniently short half-life, and clearance which is half renal (56 ml/min) and half metabolic (43 ml/min), giving a total clearance of 99 ml/min.
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  • 28
    ISSN: 1432-1041
    Keywords: indobufen ; platelet aggregation ; single dose ; bioavailability ; pharmacodynamics ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Six healthy volunteers received single iv and oral doses of 2-[p-(1-oxo-2-isoindolinyl)phenyl] butyric acid 100 mg (indobufen; K 3920), an inhibitor of platelet aggregation. Plasma levels and urinary excretion of the drug were determined by GLC. Collagen-induced platelet aggregation was assessed turbidimetrically at various intervals after administration. The plasma half-life of the drug was 7–8 h and more than 70% of the administered dose was recovered within 48 h in urine, as unchanged drug and as the glucuronide of indobufen. After oral administration of tablets of two different formulations, the drug was completely absorbed, but one formulation showed faster absorption. The maximal inhibitory effect on platelet aggregation was observed 1 to 4 h after iv administration, and it had decreased by 8 h. After tablets, peak effect and the time of the peak were similar, but activity was significantly prolonged, in accordance with the higher plasma levels found at 8 h. The data suggest that the effect of indobufen on platelets is reversible, and that for this drug platelets behave as a compartment that slowly equilibrates with plasma.
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  • 29
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    European journal of clinical pharmacology 16 (1979), S. 45-48 
    ISSN: 1432-1041
    Keywords: quinidine ; slow release formulation ; pharmacokinetics ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of quinidine in two sustained release preparations A and B has been compared in three females and three males with i.v. administration of quinidine. The initial rate of oral absorption did not differ between the two drug preparations; the peak concentration was observed after 4 h both for A and B, but was significantly higher after B. A slower decrease in plasma concentration was observed after preparation A than B. Absolute bioavailability did not differ significantly between A (median value 78.4%) and B (median 87.1%). Drug absorption in vivo was in good agreement with the results of in vitro dissolution tests on both preparations. The slower decrease in plasma concentration found for the new sustained release form of quinidine should be of clinical advantage.
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  • 30
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    European journal of clinical pharmacology 10 (1976), S. 183-187 
    ISSN: 1432-1041
    Keywords: Hydralazine ; bioavailability ; pharmacogenetics ; first pass effect ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary After oral administration of a single 50 mg dose of hydralazine (Apresoline®), the serum half-life (T1/2) and bioavailability (AUC0−∞) were assessed in 16 healthy volunteers. The half-life was 2.57±0.14 h (S.E.) in 10 slow acetylators of sulphadimidine, and 2.18±0.15 h in 6 fast acetylators (difference not statistically significant). AUC0−∞ was significantly higher in slow acetylators, at 1.04±0.10 µg·hour·ml−1, compared to 0.66±0.12 µg·hour·ml−1 in the fast acetylators (p〈0.025). Treatment with Apresoline® 25 mg tid produced minimum serum concentrations at steady-state of 57.3±7.3 ng·ml−1 and 33.4±4.2 ng·ml−1 in 8 slow and 5 fast acetylators, respectively (p〈0.05). The corresponding maximum concentrations were 228.8±20.3 ng·ml−1 and 147.6±15.0 ng·ml−1 in slow and fast acetylators, respectively (p〈0.025). First-pass metabolism of hydralazine could explain the difference in bioavailability of the drug between fast and slow acetylators, without any corresponding difference in the elimination rate of the drug in the post-distributive phase.
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  • 31
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    European journal of clinical pharmacology 10 (1976), S. 395-401 
    ISSN: 1432-1041
    Keywords: Hydralazine ; bioavailability ; polymorphic acetylation ; first-pass metabolism ; oral and intravenous dosing
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of orally administered hydralazine was assessed in 4 healthy subjects after separate administration of a single oral or intravenous dose (0.3 mg·kg−1). Comparison of the areas under the serum concentration-time curves showed that 26 – 55 % of the oral dose was available to the systemic circulation as unchanged drug. The O - 24 h excretion of the drug in urine was rapid: 11.4 – 14.1 % of the dose after intravenous administration, and 2.0 – 3.6 % after an oral dose. Acetylation of hydralazine leads to formation of 3-methyl-s-triazolo-3,4,a-phthalazine (MTP) and a gas-liquid-chromatographic method for its measurement in urine was developed. After oral and intravenous administration, 0.8 – 1.2 % and 1.4 – 2.3 % of the dose, respectively, were recovered within 24 hours from urine as MTP. After oral administration there was a relative increase in the amount of MTP in every subject, which indicates route-dependent metabolism. The lower bioavailability of oral hydralazine could be explained in terms of first-pass metabolism.
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  • 32
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    European journal of clinical pharmacology 16 (1979), S. 335-340 
    ISSN: 1432-1041
    Keywords: cimetidine ; enterohepatic circulation ; irregular absorption ; bioavailability ; pharmacokinetics ; volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability and pharmacokinetics of cimetidine have been studied in healthy volunteers after administration of single intravenous (100 mg) and oral doses (100, 400 and 800 mg). After i.v. administration, the kinetics of cimetidine could be described by a linear, two compartment open model. Substantial variation in half-life was observed between subjects, with a mean value of 2.1 h (range 0.9–4.7). Cimetidine had a low hepatic extraction ratio and a high total plasma clearance, due to extensive urinary excretion of unchanged drug. After oral administration, the plasma concentration vs time curves in most subjects exhibited two marked peaks, an observation that seemed to be constant within individuals and was independent of dose. Bioavailability, estimated as the area under the plasma concentration vs time curves (AUC), after oral doses as compared to the intravenous dose, in most cases exceeded 100%. There was no correlation between bioavailability estimated as AUC and as urinary excretion of unchanged drug. These observations may indicate an enterohepatic circulatory mechanism, predominantly after oral administration. Both unchanged drug and its sulphoxide metabolite appear to be excreted in bile. The latter was shown in vitro to be reduced to cimetidine by fecal bacteria.
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  • 33
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    European journal of clinical pharmacology 13 (1978), S. 267-274 
    ISSN: 1432-1041
    Keywords: Chlordiazepoxide ; benzodiazepines ; pharmacokinetics ; bioavailability ; intramuscular injection ; alcohol withdrawal
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of oral and intramuscular (i. m.) chlordiazepoxide hydrochloride (CDX · HCl) was compared in two pharmacokinetic studies. In Study One, single 50-mg doses of CDX · HCl were administered orally and by i. m. injection to 14 healthy volunteers using a crossover design. Whole-blood concentrations of chlordiazepoxide (CDX) and its first active metabolite, desmethylchlordiazepoxide (DMCDX), were determined in multiple samples drawn after the dose. Mean pharmacokinetic variables for CDX following oral and i. m. administration, respectively, were: highest measured blood concentration, 1.65 vs 0.87 µg/ml (p〈0.001); time of highest concentration, 2.3 vs 7.6 h after dosing (p〈0.001); apparent absorption half-life, 0.71 vs 3.39 h (p〈0.001). Biphasic absorption after i. m. injection, consistent with precipitation at the injection site, was observed in 9 of 14 subjects. Based upon comparison with previous intravenous data, the completeness of absorption was 100% for oral vs 86% for i. m. CDX · HCl (p〈0.1). In Study Two, 28 male chronic alcoholics with clinical manifestations of the acute alcohol withdrawal syndrome were randomly assigned to one of four treatment conditions: 50 or 100 mg doses of CDX · HCl, by mouth or by i. m. injection. Concentrations of CDX and DMCDX, determined in plasma samples drawn every 20 min for 5 h following the dose, were significantly higher after oral administration of a given dose than at corresponding points in time after i.m. injection after the same dose. Thus absorption of oral CDX is reasonably rapid and complete, whereas the absorption rate of i. m. CDX is slow.
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  • 34
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    European journal of clinical pharmacology 15 (1979), S. 269-274 
    ISSN: 1432-1041
    Keywords: phenytoin ; food-intake ; bioavailability ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of food intake on the absorption of phenytoin was examined in eight healthy volunteers, by study of single-dose kinetics following ingestion of phenytoin 300 mg either with a standardized breakfast or on an empty stomach. Blood samples were collected at regular intervals from 0 to 48 h, and serum concentrations of unmetabolized phenytoin were determined by gas chromatography. Serum concentrations of the major metabolite of phenytoin, 4-hydroxyphenytoin, were measured by mass fragmentography. Concurrent intake of food and phenytoin appeared to accelerate absorption of the drug from the formulation used, and the peak concentrations were significantly higher (mean increase 40%) in the postprandial than in the preprandial state. As reflected by the AUC (area under the curve), the amount of drug absorbed was increased during postprandial conditions, although the difference only reached borderline significance. It is suggested that phenytoin should always be taken in a defined relation to meals.
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  • 35
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    European journal of clinical pharmacology 16 (1979), S. 107-112 
    ISSN: 1432-1041
    Keywords: quinidine ; enteric-coated tablets ; bioavailability ; gastric emptying ; pH
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of quinidine from single and multiple doses of an enteric-coated preparation (Systodin®) was studied in seven healthy subjects, and was compared with the pharmacokinetics of intravenously administered quinidine and the results of in vitro dissolution tests of the tablets. Absorption of quinidine began after a variable delay, 2–8 h (mean 4.8) after fasting and 3–10 h (mean 6.1) after food. The rate of absorption varied both in and between individuals. It appeared to be lower when the drug was administered after food. Multiple doses after food gave a pattern of plasma concentration-time curves similar to that found on administration of single doses after food. The delay prior to absorption was prolonged at night. The ratio between the maximum and minimum concentration of quinidine during a dose interval varied from 1.3 to 3.2 (mean 2.0). Bioavailability of quinidine in fasting subjects ranged from 69 to 95% (mean 83); variation was greater when doses were administered after food. The release of quinidine from the enteric-coated preparation was pH dependent and was sustained at low pHs as may be found in the intestines. The results indicate that the absorption of quinidine from the enteric-coated formulation was dependent on the highly variable rate of gastric emptying and the pH of intestinal fluid, and it varied greatly both within and between individuals.
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  • 36
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    European journal of clinical pharmacology 16 (1979), S. 141-147 
    ISSN: 1432-1041
    Keywords: prazepam ; N-desmethyldiazepam ; bioavailability ; pharmokinetics ; electron-capture gasliquid chromatography
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary An original electron-capture gas chromatographic assay was developed for simultaneous measurement of plasma levels of the benzodiazepine derivative prazepam and of its principal unconjugated metabolite, N-desmethyldiazepam. The assay was used to study the pharmacokinetics of the drug and its comparative bioavailability from tablets and from a specially prepared solution. Nine healthy adult volunteers were studied. Each volunteer on one occasion took 30 mg of the drug in tablet form, and on another occasion 30 mg of the drug in solution. In all subjects, N-desmethyldiazepam appeared in plasma shortly after prazepam appeared and reached a peak within four hours of prazepam ingestion. Thereafter plasma N-desmethyldiazepam levels were much higher than plasma prazepam levels throughout. Prazepam became undetectable within six hours of intake, whereas its metabolite could still be measured in plasma fourteen days after dosage. Thus much of the pharmacological action of prazepam may be mediated through its metabolite, N-desmethyldiazepam. In five of the nine subjects, areas under the plasma level curves for the metabolite were not markedly different for the tablet and solution formulations studied. In the other four subjects the area under the curve for the tablets was 50% to 80% of the area under the curve for the solution. The time to reach peak plasma level for the metabolite was shorter after the solution formulation (mean 2.0±SD 1.2 h) than after the tablet formulation (mean 4.2±SD 1.7 h).
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  • 37
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    European journal of clinical pharmacology 10 (1976), S. 55-58 
    ISSN: 1432-1041
    Keywords: Penicillin V ; bioavailability ; pharmacokinetics ; dose ranging
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary An absorption study was performed in ten healthy volunteers to test the bioavailability of various doses of two penicillin V-K preparations: Isocillin® (Hoechst AG, Federal Republic of Germany), — tablets of 600 000 and 1.2 Mega U; V-Cillin® (Eli Lilly, USA), — tablets of 200 000, 400 000 and 800 000 U. The serum concentrations and elimination of the active substance in urine were measured for six hours after administration. Independently of the source of the preparation, a strict linear relation between the dose and the area under the serum curve (AUC), or between the dose and the urinary elimination, was demonstrated by regression analysis. The dose-dependent increase in the AUC was highly significant (p〈0.01) in the range tested, i.e. between 200 000 and 1.2 Mega U. The relative elimination of active substance in urine lay within narrow limits for all doses (35.7–41.3%). Thus, both compounds proved to have the same bioavailability.
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  • 38
    ISSN: 1432-1041
    Keywords: Ampicillin ; bioavailability ; pharmacokinetics ; branded products ; proprietary preparations ; capsule formulation ; tablet formulation
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of three different brands of ampicillin were studied in 10 volunteers. After intravenous administration ampicillin can be described adequately by a two-compartment open pharmacokinetic model. The half-life during the α-phase was 9 min and the β-half-life was in the range 50–60 min, independent of the mode of administration. Absolute bioavailability was determined from the ratio of the areas under the serum concentration curves obtained after oral and intravenous administration of equal doses. Bioavailability was also estimated by analysis of variance. The results indicated absolute availability of the three products of 39–54%. One of the products, a capsule formulation, showed a significantly lower bioavailability than the others, which were tablet formulations.
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  • 39
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    European journal of clinical pharmacology 11 (1977), S. 277-281 
    ISSN: 1432-1041
    Keywords: Proscillaridin ; oral administration ; portal venous sample ; porto-peripheral concentration difference ; bioavailability ; 86Rb-uptake inhibition assay
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of proscillaridin A was studied in four patients undergoing catheterization of the portal vein for diagnostic purposes. Proscillaridin 1.5 mg was given as a single oral dose and plasma glycoside activity was analyzed by the86Rb-uptake inhibition technique. Proscillaridin appeared rapidly in the portal blood, peak activity being found after 15 min in three and after 30 min in one patient. In peripheral blood the peak activity occurred after approximately 35 min. Despite rapid passage across the gut wall, porto-peripheral differences in glycoside activity were small; they were zero after 4 h. The mean amount absorbed as active proscillaridin during the first 4 h after the dose was calculated to be only 7.1% of the given amount. Late porto-peripheral differences, probably due to enterohepatic recycling, appeared after 6 h in three patients. The results suggest that proscillaridin undergoes first pass inactivation in the gut wall. Enterohepatic recirculation may contribute to the amounts of active glycoside that reach the systemic circulation.
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  • 40
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    European journal of clinical pharmacology 10 (1976), S. 49-54 
    ISSN: 1432-1041
    Keywords: Three-compartment open model ; intravenous infusion ; apparent volume of distribution ; renal insufficiency ; miconazole ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic profile of miconazole has been studied in normal subjects and in patients suffering from severe renal insufficiency; one group of patients was undergoing intermittent haemodialysis. A three-compartment open model was fitted to the observed plasma concentrations obtained after intravenous infusion of miconazole 522 mg over fifteen minutes. The rate constants of elimination and exchange between compartments computed for the three groups were not significantly different. The apparent volumes of distribution in the cases of renal failure not undergoing haemodialysis were significantly smaller than the corresponding control values. A computational procedure is described which reduces observations obtained after infusion to the case of a single rapid intravenous administration.
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  • 41
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    European journal of clinical pharmacology 11 (1977), S. 207-212 
    ISSN: 1432-1041
    Keywords: Chlorpropamide ; hypoglycaemic agent ; bioavailability ; plasma concentrations ; bioequivalence ; dissolution tests
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of chlorpropamide from two new formulations (Melitase® tablets) has been compared to that from a reference formulation which is currently in clinical use as a hypoglycaemic agent. In both rate and extent of bioavailability, all three formulations may be considered equivalent, providing allowances are made for differences in drug content. With 95% confidence, the mean bioavailability of chlorpropamide from the new formulations was within about 16% of the mean from the reference formulation, and formulation-related differences were not statistically significant. Although all three formulations were shown to have similar dissolution profiles, dissolution of chlorpropamide was pH-dependent in vitro. Dissolution was almost complete during 30 min at pH 7.2, but only 40%–60% had dissolved during 90 min at pH 2.0. A peak mean concentration of 22.7 µg/ml was reached 3 h after administration of 2×100 mg tablets of the new formulation and peak mean concentrations of 26.8 µg/ml and 27.4 µg/ml were reached 3 h and 4 hours after administration of one 250 mg tablet of the new formulation and one 250 mg tablet of the reference formulation respectively. Formulation-related differences of mean plasma concentrations (after scaling for equal doses of 250 mg) were not significant and each formulation provided similar plasma concentrations at corresponding times after administration. Statistically significant subject-related differences in all the parameters of bioavailability were shown by analyses of variance.
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  • 42
    ISSN: 1432-1041
    Keywords: ergotamine ; migraine ; bioavailability ; radioimmunoassay ; plasma level ; CSF level ; continuous dosing
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma ergotamine concentrations were determined by radioimmunoassay in 10 healthy subjects after a 2 mg oral dose of ergotamine, administered at 24 h intervals on three consecutive days. After the first dose the mean peak plasma level of 0.35±0.05 (SEM) ng/ml was found 1–2 h after administration. In the samples obtained 2 h after the second and third doses, plasma ergotamine levels did not exceed the first peak value. On the other hand, after the third and last dose the plasma ergotamine began to rise slowly, reaching maximum of 0.70± 0.10 ng/ml on the 6th day after administration. This supports the concept of accumulation of the drug or of immunoreactive metabolites. CSF ergotamine was determined in 4 patients, who underwent lumbar puncture for other diagnostic purposes, 1 to 2 h after the 2 mg oral dose. A concentration of 0.40± 0.03 ng/ml was observed. In seven out of 18 migraine patients who were taking ergotamine preparations daily (mean 11.7 mg/week), ergotamine could not be detected in plasma 1 h after administration of the dose. In the remaining migraine patients, the pattern of plasma ergotamine after both the daily and the test doses was similar to that of the 10 healthy subjects. The results in volunteers and migraine patients suggest notable variation in bioavailability of the drug. It seems that in most subjects there is accumulation or tissue redistribution of ergotamine or its immunoreactive metabolites, although in a significant number of migraine patients who use the drug daily, ergotamine does not appear to be biologically available.
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  • 43
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    European journal of clinical pharmacology 16 (1979), S. 405-410 
    ISSN: 1432-1041
    Keywords: diclofenac ; plasma levels ; intravenous bolus administration ; oral administration ; enteric coating ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of diclofenac were examined following single rapid intravenous injection and also following single oral doses to healthy female volunteers. After intravenous injection plasma levels of diclofenac fell rapidly and were below the limits of detection at 5.5 h postdosing. Individual drug profiles were described by a triexponential function and mean half-lives of the three exponential phases were 0.05, 0.26 and 1.1 h. After oral doses of enteric-coated tablets, the lag time between dosing and the appearance of drug in plasma varied between 1.0 and 4.5 h. However once drug absorption had commenced similar plasma drug profiles were obtained in different individuals. Peak plasma diclofenac levels ranged from 1.4 to 3.0 µg · ml−1. The mean terminal drug half-life in plasma was 1.8 h after oral doses. This value was not significantly greater than the value of 1.1 h following intravenous doses. Fifty percent of orally dosed diclofenac did not reach the systemic circulation due, predominantly, to first-pass metabolism.
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  • 44
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    European journal of clinical pharmacology 11 (1977), S. 219-224 
    ISSN: 1432-1041
    Keywords: Nortriptyline ; 10-OH-nortriptyline ; bioavailability ; plasma metabolites ; first pass metabolism ; oral dose ; intramuscular dose
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Nortriptyline was given orally and intramuscularly to six depressed patients. Plasma concentrations of parent drug and the unconjugated and conjugated principal metabolite, 10-hydroxynortriptyline, were determined by mass fragmentography. There was a significant decrease in the area under the nortriptyline plasma concentration — time curve after the oral route of administration, whilst the elimination rate was unchanged. With the oral dose, plasma concentrations of the metabolites were higher and peaked earlier than after intramuscular administration, whilst the opposite was true for the parent compound. This proves that the difference in bioavailability between the two routes of administration was due to first pass metabolism. As determined from the ratio between corresponding areas, the relative bioavailability of the oral dose was 66±21 S.D. per cent. This fraction is higher than that reported previously when intravenous nortriptyline was used as the reference dosage form.
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  • 45
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    European journal of clinical pharmacology 12 (1977), S. 281-284 
    ISSN: 1432-1041
    Keywords: Tetracycline ; bioavailability ; plasma levels ; nutritional state ; man
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Relative bioavailability after oral administration of a single dose and Cmin levels of tetracycline in plasma after multiple doses were determined in groups of well-nourished and undernourished subjects. The relative bioavailability of tetracycline, assessed by the area under serum concentration time-curves, did not differ in undernourished and well-nourished patients. The plasma levels were not different in the two groups after the conventional dose of tetracycline HCl 250 mg at 6 hour intervals. However, in these studies undernourished subjects received a higher dose per kg body weight, which could have compensated for any effect of a shortened half life of the drug. When the dose per kg body weight was reduced, the Cmin levels were lower. On the other hand, with the same dose per kg body weight at more frequent intervals, the plasma concentrations were similar to those in well-nourished subjects. These studies indicate that the dosage regimen should be based both on body weight and on the nutritional status of the individual.
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  • 46
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    European journal of clinical pharmacology 12 (1977), S. 65-68 
    ISSN: 1432-1041
    Keywords: Indomethacin ; antacids ; drug-drug interactions ; bioavailability ; drug combinations
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The biovailability of indomethacin from two indomethacin-antacid (aluminum hydroxide magnesium carbonate and magnesium hydroxide) combinations was compared with the bioavailability of oral indomethacin. Relative bioavailability was estimated by three methods: comparison of plasma concentrations at various times, comparison of areas under plasma concentration time curves, and comparison of the amount of drug excreted unchanged in the urine. A double blind three-way crossover study was conducted in twelve healthy volunteers. The combination with the slightly smaller amount of antacid (preparation A) showed significantly decreased bioavailability by all three methods in comparison with indomethacin alone (preparation C). The combination with the larger amount of antacid (preparation B) was also less bioavailable than preparation C. This effect was significant only for the comparison of areas under curves and not for plasma levels, although the mean plasma levels produced by preparation B at all times were lower than those for preparation C. These findings suggest that aluminum hydroxide magnesium carbonate and magnesium hydroxide decrease the bioavailability of indomethacin.
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  • 47
    ISSN: 1432-1041
    Keywords: Tolmetin ; pharmacokinetics ; bioavailability ; antacid ; oral dose
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The purpose of this study was to determine whether a concomitant single dose of antacid or multiple doses of antacid administered prior to, and with tolmetin, alter the pharmacokinetics of tolmetin when the drug was administered as a commercially available tablet containing tolmetin sodium. The possible effects of the antacid on plasma concentrations and urinary excretion of tolmetin and its major metabolite were evaluated following administration of: (a) tolmetin sodium alone; (b) antacid four time a day for three days prior to a single dose of tolmetin sodium, with continuation of the antacid during the day tolmetin was given; and (c) co-administration of single doses of tolmetin sodium and antacid. The twenty-four subject study was of the crossover type. There were no significant differences among treatment means for: (i) peak plasma concentrations of both tolmetin and metabolite, (ii) AUC 0–8 h and AUC 0-∞ for both tolmetin and metabolite, (iii) time to peak plasma concentration for both tolmetin and metabolite, (iv) plasma concentrations of both tolmetin and the metabolite at all sampling times (except for tolmetin at 2 h), (v) renal clearance of both tolmetin and its metabolite, and (vi) the amount of metabolite excreted in the 0–24 h urine. There were small, but significant, differences among amounts of tolmetin excreted in the 0–24 h urine. Semilogarithmic plots of both tolmetin and metabolite plasma concentrations past the peak concentrations were curved over the entire 8-h observation period; although the elimination half-life of tolmetin has been reported to be about one hour, the half-life most probably exceeds 2.6 h in most subjects. The results of this study indicate a lack of a significant drug-drug interaction between the non-steroidal anti-inflammatory agent, tolmetin sodium, and a commonly used antacid, which is a mixture of magnesium and aluminium hydroxides.
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  • 48
    ISSN: 1432-1041
    Keywords: Coumarin ; 7-Hydroxycoumarin ; drug disposition ; first-pass effect ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of coumarin (C) upon i.v. and p.o. administration and its metabolites 7-hydroxy-coumarin (7-HC) and 7-hydroxy-coumarin glucuronide (7-HCG) have been studied. Six healthy volunteers were involved in this investigation. Four of the volunteers participated in a crossover study. Coumarin was administered i.v. and p.o. in dose sizes of 0.25 mg/kg and 0.857 mg/kg, respectively. Coumarin is rapidly absorbed p.o., however the availability to systemic circulation is less than 4%. The rest of the dose appears quantitatively as 7-HC and 7-HCG in systemic circulation suggesting an extensive firstpass effect. Coumarin and 7-HCG are best fitted to an open two-compartment model, whereas 7-HC is best fitted to an open one-compartment model. The biological half-life of both C (0.80 vs. 1.02 h) and 7-HCG (1.47 vs. 1.15 h) was not significantly different for the two routes of administration. The large total clearance of C again suggests a first-pass effect; while that of 7-HCG, which is nearly exclusively eliminated into urine, indicates active tubular secretion of the glucuronide.
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  • 49
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    European journal of clinical pharmacology 13 (1978), S. 35-39 
    ISSN: 1432-1041
    Keywords: Norethindrone ; bioavailability ; man ; competitive protein binding ; sex differences ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A competitive protein binding assay for norethindrone was developed to measure plasma levels in human subjects. The plasma levels were considerably higher in women than in men, especially at low dose levels. The plasma levels were directly related to the dose in men; but greater variations in the plasma levels were observed in women. The plasma half-life was about 5 h in both sexes with single oral doses of 5 to 20 mg. A comparative bioavailability study with norethindrone from 2 different manufacturers, formulated in the same manner, showed no significant differences in absorption characteristics and provided sufficient data for pharmacokinetic analysis.
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  • 50
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    European journal of clinical pharmacology 14 (1978), S. 261-265 
    ISSN: 1432-1041
    Keywords: Procainamide ; slow release formulations ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Procainamide was given to 20 patients with normal renal function as an i.v. bolus of 500 mg followed by 1.0 or 1.5 g eight-hourly by mouth in the form of a slow release preparation (Durules). 97.6±27.1 (SD)% of the oral procainamide was absorbed, the absorption half life being 1.54 h. The elimination half life following the oral formulation was 6.0±0.8 h, compared to a mean of 3.4±0.4 h following i.v. administration. Elimination half life following i.v. administration was slightly related to acetylator status, being 2.75±0.9 h in fast acetylators, and 4.4±2.4 h in slow acetylators. This dependence on acetylator status was not seen in half life following oral administration. Total body clearance, steady state plasma procainamide and N-acetylprocainamide were not significantly dependent on acetylator status, although a few patients who are slow acetylators had unexpectedly low clearance and high steady state procainamide concentrations when given the higher dose.
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  • 51
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    European journal of clinical pharmacology 14 (1978), S. 357-360 
    ISSN: 1432-1041
    Keywords: Lanoxin tablets ; Lanoxicaps ; sorbitol ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary (1) The mean cumulative urinary digoxin excretion over 8 days was compared in 8 healthy volunteers after single doses of digoxin administered as 3 Lanoxin tablets of 0.25 mg, 3 digoxin tablets of 0.2 mg, 12 Lanoxicaps without sorbitol of 0.05 mg, 6 Lanoxicaps without sorbitol of 0.1 mg digoxin, 3 Lanoxicaps without sorbitol of 0.2 mg and 3 Lanoxicaps with sorbitol of 0.2 mg. (2) There was no significant difference between the 8 day cumulative urinary excretion for any of the Lanoxicaps treatments. (3) Cumulative urinary excretion after 3 digoxin tablets of 0.2 mg was significantly (P〈0.05) lower than after all other treatments. (4) Cumulative urinary excretion after 3 Lanoxin tablets of 0.25 mg was not significantly different from that after any of the Lanoxicaps treatments except 0.1 mg Lanoxicaps without sorbitol, it was significantly (P〈0.05) lower after the latter. (5) Mean urinary excretion of digoxin was 60% of ingested dose for all Lanoxicaps treatments and was significantly (P〈0.05) higher than the mean value of 50% for both tablet treatments. (6) Enhanced absorption of digoxin from Lanoxicaps was confirmed and shown to be unrelated to the sorbitol content of the capsule shell.
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  • 52
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    Archives of microbiology 112 (1977), S. 123-126 
    ISSN: 1432-072X
    Keywords: Bandeiraea simplicifolia ; Schizosaccharomyces pombe ; Colloidal gold ; Cytochemistry ; α-Galactomannan-lectin ; Scanning electron microscopy
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    Topics: Biology
    Notes: Abstract Galactomannan was localized by scanning and transmission electron microscopy on the cells and cell walls of Schizosaccharomyces pombe. The markers were prepared from colloidal gold granules labelled with an α-galactopyranosyl-binding lectin isolated from the seeds of Bandeiraea simplicifolia. Part or all of this α-galactomannan was present in the outer layer of the cell wall and was uniformly distributed even on the fission scars.
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  • 53
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    Archives of microbiology 109 (1976), S. 9-14 
    ISSN: 1432-072X
    Keywords: Candida utilis ; Saccharomyces cerevisiae ; Colloidal gold ; Cytochemistry ; Mannan ; Plasma membranes ; Scanning electron microscopy
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    Topics: Biology
    Notes: Abstract The β(1→3)glucanase of Basidiomycete QM 806 was used to prepare Saccharomyces cerevisiae and Candida utilis protoplasts. Plasma membranes isolated from S. cerevisiae contained a small amount of mannose and traces of glucose and ribose. Randomly distributed α-mannan was detected by scanning electron microscopy at the surface of prefixed protoplasts using colloidal gold labelled with Concanavalin A as a marker. C. utilis protoplasts were also marked with anti-mannan antibodies. Again the distribution of mannan was random. This experiment indicated also that plasma membrane mannan has the same immunochemical determinants as cell wall mannan. It is hypothesized that mannan is mainly located in the outer layer of plasma membranes.
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  • 54
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    Archives of microbiology 109 (1976), S. 31-35 
    ISSN: 1432-072X
    Keywords: Scanning electron microscopy ; Chlamydomonas ; Cell agglutination ; Cell fusion ; Flagella
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    Topics: Biology
    Notes: Abstract A technique has been developed by which mating gametes of Chlamydomonas eugametos can be studied in the Scanning Electron Microscope. A detailed description of the mating process, from the initial flagellar agglutination until the release of free vis-à-vis pairs, is presented. Flagella appear to agglutinate at random points on their surface. This is followed by a rapid increase of the contact area such that they “line-up” tip to tip. Flagella always exhibit a typical position prior to cell fusion. After cell fusion the flagella of a pair separate rapidly while the female have shortened about 33%. In a vis-à-vis pair the plasma bridge has contracted. The observations are interpreted in terms of a specific reorganization of the sexuale aggregate.
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  • 55
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    Cell & tissue research 157 (1975), S. 457-465 
    ISSN: 1432-0878
    Keywords: Pecten oculi ; Pigeon ; Surface ; Function ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary A scanning electron microscopic study of the pecten reveals the rib-like character of the pectinal folds, the nature of their connections with the base and bridge of the pecten as well as the presence of interconnections between the bundles of superficial collagenous fibres. It has been suggested that the pecten may have a mechanical significance, namely protection of the retina from the excessive movements of the vitreous humour. The relationship between the superficial membrane of the folds which is continuous, the intercellular spaces and the process of diffussion has also been discussed.
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  • 56
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    Cell & tissue research 170 (1976), S. 145-159 
    ISSN: 1432-0878
    Keywords: Neurogenesis ; Retina ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary Fixed retinae of chick embryos and chicks of the first week after hatching were fractured and examined with the scanning electron microscope. The matrix cells of the retina proliferate up to the beginning of the second week. The migrating cells are oriented in cell cords. This columnar organization prevails up to the development of the plexiform layers formed as a consequence of the outgrowth of the dendritic and axonal cell processes. Special attention was paid to the differentiation of the ganglion, bipolar and receptor cells, and the radial fibers (Müller cells). Two main morphological patterns are significant for the organization of the retina during neurogenesis: a) the cell to cell contacts of migrating cells and b) the spatial arrangement of Müller cells which could provide guidelines for migration of neuronal elements.
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  • 57
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    Cell & tissue research 159 (1975), S. 73-80 
    ISSN: 1432-0878
    Keywords: Osteoblasts ; Collagen orientation ; Parietal bone ; Rat, Rhesus monkey ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary Bone was removed from the calvaria of anaesthetized 70 g rats or freshly killed young monkeys and the fibrous periosteum dissected off the inner, formative surface under 0.15 M cacodylate buffer. The bone and undisturbed osteoblasts were fixed in 3% glutaraldehyde in the same buffer for 24 to 48 hours, critical point dried and coated with evaporated carbon and gold for scanning electron microscopy (SEM). Fields of osteoblasts were photographed and chosen cells dissected off the osteoid using a tungsten needle. The control of the dissection was made possible by the use of a system of real-time stereo TV-speed SEM. The fields were rephotographed and the orientations of the osteoblasts were compared with that of the underlying collagen fibres. 62% of all osteoblasts lay with their long axes within 15° of the collagen fibre orientation below and 80% within 30°. Montages of large areas of osteoblasts were also made, and then compared with ones of the same area after the cells had been stripped off on adhesive tape. In general, the orientation of the collagen tended to be the same as the cell that formed it. Collagen fibres below cells at the periphery of a domain sometimes had the orientation of the cells in the adjacent patch. It is not possible to determine whether the cells controlled the orientation of the collagen, or vice versa, from this experiment, but other SEM evidence suggests that the collagen orientation in hard tissue matrices depends on the freedom of cells to move with respect to the matrix surface.
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  • 58
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    Cell & tissue research 159 (1975), S. 233-243 
    ISSN: 1432-0878
    Keywords: Odontoblasts ; Predentine ; Dentine ; Calcification ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary A scanning electron microscopic technique was used to investigate the surface structure of dentinogenically active odontoblasts. Thin pieces of rat incisors were fixed, rapidly frozen, freezedried at -70° C and fractured to expose new surfaces prior to examination in the SEM. Differences in the appearance of odontoblastic cell surfaces were seen, with the most extensive ridge formations at the distal part of the sides of the odontoblasts. The predentine area displayed a spongy structure which contrasted to the compact appearance of dentine. Results are discussed in relation to previous studies at the light microscopic and transmission electron microscopic levels.
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  • 59
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    Cell & tissue research 160 (1975), S. 399-410 
    ISSN: 1432-0878
    Keywords: Lung ; Frog ; Alveolar epithelium ; Mucus layer ; Scanning electron microscopy ; Transmission electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary Scanning and transmission electron microscopy were used to study the inner architecture of the frog lung. In some specimens the alveolar surface mucus layer was removed to permit the examination of underlying features. The inner surface of the frog's lung is covered by a layer of microvilli belonging to only one type of epithelial cells. The boundaries of these epithelial cells are demarcated by small ridges. Different degrees of lung expansion cause variations of the surface topography. The morphology of certain surface features is examined in detail. Several methods of drying the specimens are compared.
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  • 60
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    Cell & tissue research 161 (1975), S. 329-341 
    ISSN: 1432-0878
    Keywords: Spermatozoa ; Boar, bull, ram ; Surface ultrastructure ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé La morphologie comparée des spermatozoïdes éjaculés de Verrat, Taureau et Bélier a été étudiée au microscope à balayage. Le sperme lavé est fixé dans le glutaraldéhyde ou le mélange acide picrique-formaldéhyde-glutaraldéhyde. Les échantillons sont le plus souvent désséchés par la méthode du point critique (Fréon) sur un filtre et aussi dans l'air sur une lamelle de verre. La tête des spermatozoïdes de ces trois espèces présente la même forme en pagaie aplatie formée de trois régions principales: les deux segments, antérieur, entouré d'un épaississement marginal, et équatorial de l'acrosome et la région postacrosomique. La plupart des differentiations de la lame postacrosomique décrites en microscopie électronique à transmission sont visibles à travers la membrane plasmique, particulièrement après dessication à l'air. La morphologie superficielle du cou et des différentes parties du flagelle est aussi observable. Des différences spécifiques sont mises en évidence: chez le verrat seulement, par exemple, la surface de l'acrosome apparaît granuleuse, et aucune bordure antérieure dentelée de la lame postacrosomique n'est visible. La microscopie à balayage permet d'observer les grands traits et de fins détails de la morphologie superficielle d'un échantillon de sperme et aussi d'étudier les effects de traitements sur des spermatozoïdes (congélation, extraction de l'acrosome).
    Notes: Summary The comparative ultrastructure of ejaculated boar, bull and ram spermatozoa is studied by scanning electron microscopy. After washing, the spermatozoa are fixed in glutaraldehyde or in picric acid-formaldehyde-glutaraldehyde mixture. Samples are prepared either by critical point drying (Freon) on Millipore filters or by air drying on glass cover slips. In all the species studied, three regions may be distinguished in the paddle-shaped head of the sperm: an anterior segment (surrounded by the marginal thickening) and an equatorial segment constituting together the acrosome, and the postacrosomal region. Most of the feature of the postacrosomal lamina described in transmission electron microscopy are visible through the plasma membrane, particularly after air drying. The surface morphology of the neck and of the different segments of the flagellum is also evident. Some species differences are encountered, e.g. rough surface of acrosome and absence of serrations in postacrosomal lamina of boar spermatozoa only. The techniques employed result in good general morphology and fine resolution of surface detail of the sperm samples; they also permit analysis of spermatozoa treated by freezing or submitted to acrosomal extraction.
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  • 61
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    Cell & tissue research 174 (1976), S. 129-137 
    ISSN: 1432-0878
    Keywords: Pineal organ, human ; Acervuli ; Scanning electron microscopy ; Transmission electron microscopy ; Electron probe microanalysis
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    Topics: Biology , Medicine
    Notes: Summary Untreated, decalcified and trypsinized acervuli from human pineal bodies were studied with the scanning and transmission electron microscope as well as by electron probe microanalysis. The mulberry-like acervuli are composed of a various number of spherical lobes (135–800 μm) between which clustered groups of globuli (4–14 urn in diameter) are observed. The acervular lobes are very probably formed by an aggregation of these globuli. Small round particles 125–500 Å in diameter are observed on the surface of the pineal concretions. These are not influenced by either decalcification or trypsin treatment. The acervular mineral corresponds morphologically to hydroxyapatite. The electron probe microanalysis reveals the existence of calcium and phosphorus as main components of the acervuli. Small quantities of magnesium and strontium were also detected.
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  • 62
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    Cell & tissue research 176 (1977), S. 493-504 
    ISSN: 1432-0878
    Keywords: Pancreas ; Acinar cells ; Cell surface ; Dissociation ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The pancreatic acinar cell surfaces have been studied by SEM with a dissection technique and correlated with results obtained by TEM. The SEM results demonstrate characteristic arrangement of microplicae which in some areas are densely packed. In many areas, the microplicae are distributed in such a manner that they create zones with typical geometrical shapes and show a relatively smooth surface. These smooth areas may coincide, as indicated by correlated TEM results, with the limits of intimate contact between adjacent acinar cells which, in turn, represent part of the junctional complex. Another aspect revealed by these SEM preparations concerns the presence of groups of densely packed microplicae, arranged in regular rows and distributed along some grooves and/or infoldings of the cellular surface. On the basis of SEM and TEM information, it is likely that these structures correspond to intercellular (and possibly, in some cases, intracellular) canaliculi which topographically form a kind of extensive microlabyrinthine arrangement running along all the cell sides. One final point revealed by fractured samples concerns the finding of spherical zymogen droplets within the vesicles of the Golgi complex. Because in many scanning images these vesicles appear connected by small openings, it is suggested that they may represent a system of intercommunicating chambers (vacuoles) through which the zymogen droplets can be continuously accumulated and discharged into the acinar lumen.
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  • 63
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    Cell & tissue research 177 (1977), S. 307-316 
    ISSN: 1432-0878
    Keywords: Third ventricle ; Mature monkeys ; Scanning electron microscopy ; Ependyma
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    Topics: Biology , Medicine
    Notes: Summary Surface features of the ependymal lining of the third ventricle in mature male and female monkeys have been investigated with scanning electron microscopy (SEM). Broad aspects of third ventricular morphology from three species of monkey are similar regardless of sex. The lateral walls are heavily ciliated whereas the ventral floor and most ventral parts of the lateral walls are not. Clumps of cilia on the lateral walls are so dense that underlying surface details are usually obscured. There is a transition zone between the ciliated lateral wall and nonciliated ventral floor. The floor and lower part of the lateral walls of the third ventricle exhibit a characteristic polygonal pattern upon which surface specializations such as microvilli, blebs and polymorphous membrane protrusions are superimposed. Ependyma of the choroid plexus of the third ventricle also display membrane specializations. Supraependymal cells are more visible in nonciliated regions.
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  • 64
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    Cell & tissue research 163 (1975), S. 125-132 
    ISSN: 1432-0878
    Keywords: Bovine subcommissural organ ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The bovine subcommissural organ was studied by using scanning electron microscopy. The most prominent finding was the existence of protruded and dilated endings of the ependymal cells. The majority of these cells were ciliated with two or more cilia; only a few unciliated cells were seen. Some pore-like structures were also seen on the surface. From the functional point of view, the most interesting finding was an amorphous heterogeneous material on the subcommissural ependyma. Especially in the caudal part of the organ this material accumulated in abundance. No real filamentous structures such as Reissner's fibre could be seen, however, it was assumed that the heterogeneous material corresponds to this formation. No supraependymal neurones were demonstrated.
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  • 65
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    Cell & tissue research 163 (1975), S. 313-325 
    ISSN: 1432-0878
    Keywords: Neurogenesis ; Cerebral cortex ; Scanning electron microscopy
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    Notes: Summary Fixed cerebral vesicles of mouse foetuses were fractured and examined with the scanning electron microscope. This method provides a study of the three dimensional developmental features of the pseudostratified columnar epithelium up to the formation of the early cortex plate. Matrix cells are a cell population of homogeneous shape, however, mitotic cells are easily identified by their spherical form. The external surface of the brain is formed by the closely packed end feet of these cells covered by a basal membrane. The formation of the cortical plate is the result of a continuous cell migration in columnar arrangement towards the pia. Glioependymal cells extend along the whole brain wall and most likely provide guidance for the migrating cell cords. The formation of the so-called migratory zone is a consequence of the growth of the basal and the horizontal prolongations of emigrating cells. The significance of the cell to cell contacts for the neuronal migration processes is discussed.
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  • 66
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    Cell & tissue research 170 (1976), S. 1-16 
    ISSN: 1432-0878
    Keywords: Tissue culture cells ; Mycoplasma ; Light microscopy ; Transmission electron microscopy ; Scanning electron microscopy ; Morphometry
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    Topics: Biology , Medicine
    Notes: Summary The host-parasite relationship of HeLa M cells artificially infected with a bovine species of Mycoplasma was studied by light microscopy, transmission electron microscopy and scanning electron microscopy. The use of morphometry to quantitate some of the findings was explored. The parasites were seen in locations extracellular to the cell surface. The detection of small numbers of organisms by light microscopy was well demonstrated by use of the fluorescent antibody technique. Scanning electron microscopy proved to be an excellent method for revealing the surface details of cell-parasite morphology. Ultra-thin sections showed that the parasites are aligned mostly parallel to the plasma membrane of the host cell but separated by a gap of 10 nm. Morphometry indicated an average of 69 organisms per cell surface occupying 1.7% of the surface area. An increase of 26% in diameter of the HeLa cells, possibly as a result of infection, was observed.
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  • 67
    ISSN: 1432-0878
    Keywords: Axons ; Scanning electron microscopy ; Neurones, afferent ; Nerve regeneration ; Spinal nerve roots
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    Notes: Summary Rat dorsal spinal nerve roots were cut and the tip on the ganglionic side of the cut was examined by scanning electron microscopy at 0, 7, 20 and 48 h after operation. Seven hours after cutting, free axonal sprouts had started to protrude from the cut end of the nerve. After 20 h the free sprouts were more profuse than at 7 h but were smaller and had a rougher surface. At both 7 and 20 h many of the sprouts consisted of a stalk 2–7 μm in diameter with a bulbous end 5–20 μm in diameter. A few branching sprouts were seen. At 48 h the sprouts were shrunken with a deeply furrowed surface. The significance of the surface structure of the sprouts is discussed.
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  • 68
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    Keywords: Epididymal epithelium ; Castration ; Androgen-substitution ; Japanese monkey ; Scanning electron microscopy
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    Notes: Summary The caput epididymidis from castrated and androgen-supplemented, castrated Japanese monkeys was observed with the scanning electron microscope. The experimental findings were compared with the normal structures in control animals. The epididymal lumen of control animals was lined by a tall, pseudostratified columnar epithelium possessing long, slender stereocilia which were densely arranged in a tuft-like form. After castration, the epididymal epithelium was decreased in height to one-fifth of controls. The stereocilia were also considerably reduced in length and in number, resulting in a flattened epithelial surface with polygonal boundaries. Frequent projection of a long, single cilium from an epithelial cell into the lumen was also a prominent feature in the epididymal ducts of the castrated animals. Administration of testosterone to the castrated animals resulted in almost complete recovery of the epididymal epithelium as well as regeneration of the stereocilia which regained a tuft-like arrangement.
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    Cell & tissue research 159 (1975), S. 379-385 
    ISSN: 1432-0878
    Keywords: Compound eye ; Musca domestica ; Ommatidium ; Distal retinula ; Scanning electron microscopy ; Corneal lens ; Corneal pigment cell ; Pseudocone ; Semper cell ; Basement membrane
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    Topics: Biology , Medicine
    Notes: Summary The distal aspect of the housefly ommatidium was surveyed by the scanning electron microscope. Attention was directed to the somal eminence of the superior central cell and the lens to large pigment cell junction. The underside of each lens facet exhibits six hexagonally arranged incisures. Into each of these indentations are fitted several large pigment cells. This hexagonal indentation appears to be a tenacious anchorage. Two corneal pigment cells laterally encircle the pseudocone and at their proximal extension they enclose the Semper cells and neck of the retinula. The somal eminence of the superior central cell is about 10 μm from the base of the corneal pigment cell enclosure. Micrographs were used to construct a diagram of the ommatidium above the basement membrane. Suggestions are made as to the functional correlates of the observed ommatidial structures.
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    Cell & tissue research 172 (1976), S. 379-388 
    ISSN: 1432-0878
    Keywords: Chitons ; Receptors ; Shell surface ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The shells of the chitons Lepidochitona cinereus, Sypharochiton pelliserpentis, Amaurochiton glaucus and Onithochiton neglectus were examined by scanning electron microscopy. In all species the surface terminations of the megalaesthete and micraesthete organs could be identified lying flush with the shell surface, as well as, lenses of the shell eyes in O. neglectus. Periostracal debris and encrusting diatoms were a usual feature of the shell surfaces. The micraesthete subsidiary caps normally appear featureless, but the megalaesthete apical caps sometimes appear to be perforated. The reasons for this perforate appearance are discussed and it is concluded that it provides no evidence for the normal passage of substances out of or into the megalaesthete.
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  • 71
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    Keywords: Hypothalamo-adenohypophysial region Bufo bufo (L.) ; Portal vessels ; Methyl-methacrylate casts ; Light microscopy ; Scanning electron microscopy
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    Notes: Summary The vascularization of the hypothalamo-adenohypophysial region of the toad Bufo bufo (L.) (Amphibia, Anura) was studied by means of light- and scanning electron microscopy. Special attention was given to the portal vascular system of the median eminence and the pars distalis. Course and arrangement of these vessels are described.
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    Cell & tissue research 162 (1975), S. 377-385 
    ISSN: 1432-0878
    Keywords: Globiferous pedicellariae ; Psammechinus miliaris ; Microvilli ; Chemoreceptor ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary The globiferous pedicellariae of Psammechinus miliaris are described. Two fixation methods giving minimal distortion and rapid tissue hardening were adapted for soft tissue preparation for scanning electron microscopy. The pedicellarial valves are covered by a microvillous epithelium. The outer valve epithelial microvilli overlying red spherulocytes in the epidermis are characterized by a filament matrix radiating out from each microvillus. These microvilli may function in epidermal absorption of organic solutes. The inner valve microvilli are more densely packed and the filament matrix is absent. Ciliation is confined to the inner valve surface where the cilia are concentrated to form a distal sensory pad and sensory hillock. Behavioural evidence suggests a chemo- and mechanosensory role for the inner valve surface.
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  • 73
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    Cell & tissue research 164 (1975), S. 371-385 
    ISSN: 1432-0878
    Keywords: Kupffer cell ; Endothelial cell ; Sinusoid ; Liver ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The surface ultrastructure of Kupffer cells in the rat liver has been studied by scanning electron microscopy (SEM). The results demonstrate that Kupffer cells are both significantly different and clearly distinct from endothelial cells. Kupffer cells have neither pores (and/or “sieve plates”) nor fenestrations, all of which are present in endothelial cells. They possess a stellate shape, and only indirectly, with slender and irregular evaginations, contribute to the lining of the sinusoidal wall. Furthermore, the luminal surface in some areas contains a large population of short microvilli, microplicae and invaginations. These elements form a kind of microlabyrinth which may correspond to the “worm-like” structures described by transmission electron microscopy (TEM). In the present study, transition forms between endothelial and Kupffer cells were never found. On the contrary, considering the highly fenestrated nature of the endothelial cells, the Kupffer cells may, by ameboid movements, easily cross the overlapping barrier of the sinusoid and protrude into the lumen. Thus, acting as activated macrophages, the Kupffer cells might function to prevent the entrance of foreign material into the tissues of the liver through the fragile and highly fenestrated endothelium. Finally, the topographical reconstruction of the sinusoid by correlated SEM and TEM studies demonstrates that Kupffer cells, with their protruding cytoplasm and ability to extend into the lumen of the sinusoid, may actually change the caliber of the vessel, and thus function as a “sphincter” which causes a temporary arrest of the blood flow when the diameter of the sinusoidal lumen is reduced.
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  • 74
    ISSN: 1432-0878
    Keywords: Neuromuscular junctions ; Appendicularia (Oikopleura dioica) ; Connective tissue fibrils ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Critical point dried and fractured appendicularia of the species Oikopleura dioica have been examined in the scanning electron microscope. The dorsal nerve cord with ganglion cells and peripheral nerve fibres could easily be observed. Thick peripheral nerve fibres leave the nerve cord as bilateral pairs at constant intervals along the tail. Most of these fibres branch from the naked nerve cord, but some evidently originate in ganglion perikarya bulging out from the nerve cord itself. These paired peripheral nerves always have elaborate end-arborizations on the medial surface of the lateral muscle cells. They are accordingly interpreted as motor axons. Some thinner peripheral nerve fibres originate at irregular intervals from both the nerve cord and the ganglion cells. Due to the numerous extracellular fibrils that connect the bilateral layers of the epidermal fins and the muscle cells to each other, these thin nerve fibres can seldom be traced to their termination. A few ones can, however, be traced ventrally between the notochord and the muscle cells and seem to end in singular bulb-like expansions. Clusters of synaptic vesicles are present in transmission electron micrographs of such nerves, and they are accordingly believed to carry efferent impulses. The extracellular fibrils are arranged in a highly ordered pattern with thick bundles crossing the gap between the structures to be interconnected and with numerous radiating insertions on the surface of the tissues.
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  • 75
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    Cell & tissue research 166 (1976), S. 65-70 
    ISSN: 1432-0878
    Keywords: Collagen ; Bone ; Cell culture ; Scanning electron microscopy
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    Notes: Summary Embryonic and young rat bone cells have been grown in culture and examined in the scanning electron microscope (SEM). Compared with cells fixed in situ and taken directly from the animal, the cultured osteoblastic cells were smoother, flatter and more extensive and showed tighter intercellular contacts. Some matrix is formed in culture and undergoes at least partial mineralization as judged by the accumulation of Ca and P measured by energy dispersive x-ray analysis. Findings concerning the morphology of the collagen arrangement were indecisive. Some superficial cells, free of surrounding matrix, resembled osteocytes in normal in vivo bone. This may indicate that a proportion of the extracellular matrix produced by the cultured cells failed to polymerise into recognizable bone matrix, and that osteocytic morphology is not dependent upon the physical characteristics of the bone matrix.
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  • 76
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    Cell & tissue research 169 (1976), S. 277-287 
    ISSN: 1432-0878
    Keywords: Rabbit gametes ; Cryofractography ; Scanning electron microscopy ; Transmission electron microscopy ; Zona pellucida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rabbit ova fertilized in vitro were prepared for scanning electron microscopy by ethanol-cryofracturing and critical-point drying methods and were also embedded and sectioned for transmission electron microscopy. Study of a region of interaction between sperm and zona pellucida with scanning electron microscopy reveals the latter to be composed of a complex network of fibers interspersed with numerous pores. Transmission electron microscopy of the same region reveals a “typical” homogeneous composition of the zona pellucida. Ultrastructural observations of thin sections passing through the region of sperm-egg interactions or through other regions of the ovum or its investments reveals very little methodological distortion of the various intracellular organelles or matrix. Application of the procedures described provides not only an elucidation of surface detail but also reveals intracellular cytoplasmic information about the same specimen during in vitro fertilization.
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  • 77
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    Cell & tissue research 169 (1976), S. 449-465 
    ISSN: 1432-0878
    Keywords: Bone ; Osteoblasts ; Cell surface ; Cell shape ; Calcitonin ; Parathyroid extract ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neonate rat endocranial osteoblasts were cultured on their bone surfaces in control medium (CC) or medium to which either parathyroid extract (PTE) or calcitonin (CT) had been added for 2, 4, 8 or 24 h. Some were cultured for 24 h in CC, then for 2, 4, 8 or 24 h in either CT or PTE medium; or for 24 h in PTE, then for 2, 4, 8 or 24 h in either CC or CT; or 24 h in CT and 2, 4, 8 or 24 h in CC. The dorsal ruffling of the cells in CC was found to be suppressed by later culturing with PTE and the disoriented cells reorganized to form arrays of parallel cells. The effects of PTE were also reversed by CC or CT: the osteoblasts in the second culture (CC) lost elongation and order, and proceeded through a proliferative phase before exhibiting the ruffling form similar to a single CC 24 h culture. PTE-cultured osteoblasts showed an increase in cell overlap and contact so that a more competent barrier was formed separating the bone from the medium. In control or CT medium, however, intercellular gaps were greater than in vivo.
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    Cell & tissue research 164 (1975), S. 467-471 
    ISSN: 1432-0878
    Keywords: Pancreas ; Islets ; Scanning electron microscopy
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    Notes: Summary The surfaces of isolated pancreatic islet cells were studied with the scanning and transmission electron microscopes. Islets were isolated from the pancreas of Wistar rats by collagenase treatment and were incubated either in glucose-free medium or in 300 mg% glucose for one hour. Immunoreactive insulin (IRI) in the media of both control and experimental preparations was assayed. Islets were then transferred to 4% glutaraldehyde, buffered with cacodylate, pH 7.4, and prepared for scanning and transmission electron microscopy. Cell masses average 200 μ in diameter. Alpha cells appear pyramidal in shape, are about 8 μ in diameter and appear in groups. Beta cells are round or oval in shape and have an average diameter of 10 μ. Glucose stimulation raised the IRI value tenfold and increased the number of blebs and other surface irregularities per unit area of beta cell surface. Comparison with transmission electron micrographs suggests that the blebs are related to the process of emiocytosis.
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    Cell & tissue research 166 (1976), S. 91-100 
    ISSN: 1432-0878
    Keywords: Kidney (rat) ; Uriniferous tubule ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The fine structure of luminal surface of clearly identified portions of uriniferous tubules has been studied by scanning electron microscopy to elucidate some controversies concerning the topography of certain surface formations. The results show a characteristic pattern of the luminal surface in the region of Henle's loop, which was assumed by previous authors, to belong to the collecting tubule. Furthermore it is demonstrated that no cilia are present within the terminal portion of the collecting tubules.
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    Cell & tissue research 174 (1976), S. 499-518 
    ISSN: 1432-0878
    Keywords: Fibroblast ; Human ; Transmission electron microscopy ; Scanning electron microscopy ; Aggregation
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    Notes: Summary The different stages during aggregation of diploid human skin fibroblasts have been examined by transmission and scanning electron microscopy. As a result of aggregation, fibroblasts form a complex tissue configuration. Numerous intercellular junctions can be observed, while the cells remain polygonal and do not develop an organised intracellular cytoskeleton. Cell division occurs only rarely. After aggregation, signs of progressive auto-digestion develop. Adhesion to a substrate results in outgrowth of the cells and monolayer formation, even when extensive cell damage had occurred. The morphology of fibroblasts in aggregates and in the monolayers, from which they were derived, is compared and the contribution of the aggregate system to the study of fibroblast behavior is discussed.
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    Cell & tissue research 166 (1976), S. 299-314 
    ISSN: 1432-0878
    Keywords: Renal glomerulus (Rat) ; Endothelial cells ; Blood capillaries ; Scanning electron microscopy
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    Notes: Summary The rat kidney was perfused with saline and glutaraldehyde, treated with Murakami's tannin-osmium impregnation method, ethanol-freeze cracked and dried by the critical point method. Gold-palladium evaporated specimens were observed in a field-emission scanning electron microscope. The glomerular filtration membrane, fractured in different planes was observed with the following results: 1. Adjacent pedicles originate from different podocytes. No interpedicular bridges of apparent cytoplasmic nature could be found. 2. The basement membrane, in grazing fractures shows a horizontally layered architecture. 3. The attenuated endothelial sheet (lamina fenestrata) is divided into compartments, which we suggest should be called “areolae fenestratae”, by cytoplasmic crests radiating from the nucleated portion of the endothelial cell. A crest also occurs along the cell margin, which contacts a similar crest at the margin of the adjacent cell. 4. The pores in the areolae fenestratae are variable in size (30−150 nm diameter). A knob-like projection from the apparently naked basement membrane is found in a portion of the pores. 5. Numerous microvilli may occur on the endothelium. Some of them anastomose and fuse with one another to form a net whose meshes appear identical with the endothelial pores. Domes and shelves formed of a fenestrated cytoplasmic sheet also occur above the ordinary level of the endothelial lining. A hypothesis implicating microvilli in partial renewal of the endothelial sheet is proposed. This study was assisted by Mr. K. Adachi of the SEM Laboratory at the Niigata University School of Medicine.
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  • 82
    ISSN: 1432-0878
    Keywords: Blood vessels ; High voltage electron microscopy ; Scanning electron microscopy
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    Notes: Summary The luminal surface features and Junctional complexes from developing blood vessels in the rat central nervous system have been studied by high-voltage electron microscopy and scanning electron microscopy. Developing blood vessels exhibit three types of luminal projections; marginal folds or ridges at Junctional complexes, ridges not at Junctional complexes and microvilli. Both types of ridges are associated with troughs or depressions in the luminal surface of the endothelial cell. Those ridges not associated with Junctional complexes take part in the production of enclosed tunnels in the endothelial cell cytoplasm. Fusion of the external leaflets of Junctional complexes between adjacent endothelial cells occurred, initially, near the luminal surface of the blood vessel with other small fusion sites forming in the direction of the basal lamina secondarily. Further fusion activity to produce the zonula occludens type junction appeared to spread outwards from the smaller fusion sites.
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  • 83
    ISSN: 1618-2650
    Keywords: Analyse von Polycyclen in Lebensmitteln, Erdölprodukten, Abgasen, Tabakrauch ; Chromatographie, Gas ; gepackte Glassäulen
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    Fresenius' Zeitschrift für analytische Chemie 279 (1976), S. 161-162 
    ISSN: 1618-2650
    Keywords: Nachw. von Hormonmetaboliten in Biolog. Gewebe ; Chromatographie, Gas ; Radio-GC
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    Fresenius' Zeitschrift für analytische Chemie 280 (1976), S. 32-32 
    ISSN: 1618-2650
    Keywords: Best. von Äthylenglykol, Diäthylenglykol, Triäthylenglykol in Wasser ; Chromatographie, Gas
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    Fresenius' Zeitschrift für analytische Chemie 291 (1978), S. 299-307 
    ISSN: 1618-2650
    Keywords: Analyse von Kohlenwasserstoffen in Luft ; Chromatographie, Gas ; Tieftemperaturgradientenrohr
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    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird über ein gas-chromatographisches Verfahren zur Bestimmung von Alkanen, Alkenen und Aromaten in der Außenluft berichtet, bei dem die Probenahme an Tenax GC oder Carbopack mit Hilfe eines Tieftemperaturgradientenrohres erfolgt und die Analyse unter Einsatz eines Doppelsäulensystems in Verbindung mit zwei Flammenionisationsdetektoren durchgeführt wird. Eingehende Untersuchungen zum Verhalten der Substanzen bei der Probenahme zeigen, daß die Trocknung der Probeluft mit Magnesiumperchlorat das Ergebnis nicht beeinflußt und für Kohlenwasserstoffe mit drei oder mehr C-Atomen keine auf Durchbruch zurückzuführenden Substanzverluste zu befürchten sind. Bei einem Probenahmevolumen von 51 Luft können 2 μg Substanz/m3 gut bestimmt werden. Für Außenluft-Konzentrationen von 45 μg Benzol/m3, 95 μg Toluol/m3 und 35 μg n-Pentan/m3 betrugen die Standardabweichungen 3,5, 6,0 bzw. 3,6 μg/m3. Bei leichter Modifikation des Systems ist mit derselben Probenahmevorrichtung die gleichzeitige Bestimmung von Kohlenwasserstoffen mit einem Flammenionisationsdetektor und von Organohalogen Verbindungen mit einem Elektroneneinfangdetektor möglich.
    Notes: Summary A method is described for the gas-chromatographic determination of alkanes, alkenes and aromatics in ambient air. The hydrocarbons are trapped by cryogenic sampling using Tenax GC or Carbopack as adsorbing material and are analyzed in a two-column system equipped with two flame-ionization detectors. A detailed examination of the sampling procedure shows that drying the air with magnesium perchlorate does not affect the results, and losses of substances due to break-through need not be reckoned with for hydrocarbons with three and more carbon atoms. In a 51 air sample 2 μg/m3 of hydrocarbons can be determined readily. The standard deviations for benzene, toluene and n-pentane were 3.5, 6.0 and 3.6 μg/m3 at ambient air concentrations of 45, 95 and 35 μg/m3. A slight modification of the system which includes the combined use of a flame-ionization detector and an electron-capture detector permits the simultaneous determination of hydrocarbons and halogenated hydrocarbons.
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 409-409 
    ISSN: 1618-2650
    Keywords: Analyse von Dimethylterephthalat ; Chromatographie, Gas ; Oxidationsgemisch
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 410-411 
    ISSN: 1618-2650
    Keywords: Analyse von 1,3,5-Trioxan ; Chromatographie, Gas
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 39-42 
    ISSN: 1618-2650
    Keywords: Analyse von Metaboliten in Biolog. Material ; Chromatographie, Gas ; Fraktionierung durch Extraktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A new method for the gas-chromatographic multicomponent analysis of metabolites in biological material is described. It is an analytical procedure involving several extractions carried out under different conditions. In this procedure the metabolites are divided according to their functional groups and specific chemical behaviours into eight main fractions: lipids, hydrocarbons, organic acids, neutral substances, phenols, amines, amino acids and carbohydrates. Each of these fractions is derivatized; the components are separated and estimated by gas chromatography. This analytical system was applied to the determination of a number of metabolites in serum, urine, amniotic fluid, sperma, tissues and other biological materials.
    Notes: Zusammenfassung Eine Methode für die Multikomponenten-GC-Analyse von Metaboliten in Biomaterialien wird beschrieben. Das Verfahren umfaßt mehrere Extraktionen, die unter verschiedenen Bedingungen durchgeführt werden. Die Komponenten werden in Abhängigkeit von ihren funktionellen Gruppen und spezifischem chemischen Verhalten in acht Hauptfraktionen geteilt: Lipide, Kohlenwasserstoffe, organische Säuren, neutrale Substanzen, Phenole, Amine, Aminosäuren und Kohlenhydrate. Die Komponenten jeder Gruppe werden nach spezieller Derivatisierung gaschromatographisch getrennt und bestimmt. Dieses neue System ist bei verschiedenen biologischen Materialien (klinische Proben, Pflanzen- und Tiergewebe) angewandt worden.
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 117-120 
    ISSN: 1618-2650
    Keywords: Best. von Fluor ; Chromatographie, Gas ; F-spezifischer Detektor, Candoluminescenz
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    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird ein spektroskopischer fluor-spezifischer Detektor für gas-chromatographische (GC) Anwendungen beschrieben, der sich der Candoluminescenz bedient. Das Auftreten von InF-Bandenemissionen bei 233,7 nm bei Anwendung des MECA (= Molecular Emission Cavity Analysis)-Verfahrens kann als qualitatives Zeichen für die Anwesenheit von F in einer GC-Fraktion benützt werden. Nach entsprechender Kalibrierung kann die Bandenemission als Maß für die F-Konzentration in einer Fraktion dienen. Die Reproduzierbarkeit ist besser als ±2%, die Nachweisgrenze liegt bei 3,2 μg F pro Peak.
    Notes: Summary A fluorine-specific spectroscopical detector is described that takes advantage of candoluminescence. The intensity of the InF-band emission at 233.7 nm in Molecular-Emission-Cavity Analysis (MECA) is an indicator for F in a GC-fraction. After calibration the band intensity can be used as measure for the F-content in the fraction. The reproducibility is better than ±2%, the detection limit 3.2 μg F per peak.
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 385-390 
    ISSN: 1618-2650
    Keywords: Best. von Carbonsäuren, Sulfonsäuren ; Chromatographie, Gas ; Spuren in wäßrigem Medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Gas-chromatographische Methoden für die Spurenbestimmung einiger Carbonund Sulfonsäuren in wäßrigem Medium werden beschrieben. Die Nachweisvermögen für Ameisensäure, Essigsäure, Propionsäure, n-Buttersäure, n-Valeriansäure, Capronsäure, Acrylsäure, Benzoesäure und Chloressigsäure sowie für Methansulfonsäure und Äthansulfonsäure liegen zwischen 1 · 10−7 und 8 · 10−7 Mol/Liter. Anreicherung und Derivatisierung werden bei den Carbonsäuren durch Gefriertrocknung der Tetra-n-butylammoniumsalze und deren Umsetzung mit Benzylbromid zu den Benzylestern, bei den Sulfonsäuren durch Gefriertrocknung der Silbersalze und deren Umsetzung mit n-Butyljodid zu den n-Butylestern erreicht.
    Notes: Summary Gas-chromatographic methods for the determination of traces of several carboxylic and sulphonic acids in aqueous media are presented. Detection limits for formic, acetic, propionic, n-butyric, isobutyric, n-valeric, caproic, acrylic, benzoic, and chloroacetic acids as well as of methanesulphonic and ethanesulphonic acids range from 1 · 10−7 moles/liter to 8 · 10−7 moles/liter. Preconcentration and derivatisation of the carboxylic acids are achieved by freezedrying their tetra-n-butylammonium salts and converting the latter into the benzyl carboxylates using benzyl bromide. The sulphonic acids are converted to the corresponding silver salts, freeze-dried, and then esterified using n-butyl iodide.
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    Fresenius' Zeitschrift für analytische Chemie 278 (1976), S. 365-366 
    ISSN: 1618-2650
    Keywords: Best. von Acetylsalicylsäureanhydrid, Acetylsalicylsalicylsäure in Acetylsalicylsäure ; Chromatographie, Gas
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  • 93
    ISSN: 1618-2650
    Keywords: Analyse von Umweltmaterial, Pesticiden ; Chromatographie, Gas ; Capillar-, Ident. von Einzelkomponenten in komplexen Gemischen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Der Vergleich von präzise bestimmten Retentionsindices von Probe- und Referenzsubstanzen in der hochauflösenden Capillar-Gas-Chromatographie stellt eine aussagekräftige Methode der Identifizierung von Einzelkomponenten in komplexen Gemischen dar. Neben der Konstanz der GC-Parameter erfordert die präzise Bestimmung von Retentionsindices eine sehr genaue Bestimmung der Netto-Retentionszeiten. Insbesondere ist bei Anwendung einer Totzeitberechnung auf der Basis einer erzwungenen Linearisierung der log t s/Homologenzahl-Beziehung auf eine sehr genaue Retentionszeitmessung zu achten. Die Reproduzierbarkeit von präzise bestimmten Retentionsindices hängt von der Konstanz der Polarität und von der Adsorptivität der Capillarsäule ab. An ausreichend desaktivierten und konditionierten Hochleistungs-Capillarsäulen (TZ≥40) können unter der Voraussetzung einer Retentionszeit-Meßgenauigkeit von besser als 0,05% Retentionsindices über einen Zeitraum von mehreren Wochen innerhalb ±0,15 Indexeinheiten reproduziert werden. Eine Übertragung des n-Alkan bezogenen Retentionsindex-Konzeptes auf die homologe Reihe der n-Allkyl-trichloracetate (ATA) ermöglicht die Verwendung des Elektroneneinfang-Detektors (ECD) zur präzisen RetentionsindexBestimmung als Methode einer zuverlässigen Identifizierung von Substanzen im Picogrammbereich.
    Notes: Summary High resolution glass-capillary gas chromatography can be used as a powerful identification tool for single components in complex mixtures, when the matching of retention indices of reference compounds with those found in the sample is based on precise measurements. Besides the constancy of the GC-parameters high precision measurements of retention indices require an accurate determination of net retention times. Special care has to be taken for an accurate measurement of retention times when using a dead-time calculation on the basis of an enforced linearisation of the log t s/homologues-number relationship. The reproducibility of precise retention-index determinations strongly depends on the constancy of the polarity and on the adsorptivity of the capillary column. Provided a sufficiently deactivated and conditioned high performance capillary column (separation number ≥40) and an accuracy of retention-time measurement of better than 0,05 % retention indices can be reproduced within ±0.15 i.u. over a period of several weeks. A conversion of the n-alkane based retention-index concept to the use of the homologous series of n-alkyl-trichloro-acetates (ATA) allows the use of the electron-capture detector (ECD) for precise retention-index determinations for a reliable identification of compounds in the picogram range.
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 412-413 
    ISSN: 1618-2650
    Keywords: Analyse von Dimethylterephthalat in Wasser ; Chromatographie, Gas ; Abwasser
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 385-390 
    ISSN: 1618-2650
    Keywords: Nachw. von Kohlenwasserstoffen, aromat. polycycl. in Wasser ; Chromatographie, Gas ; ECD, Anreicherungsverfahren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Ein einfaches und schnelles Adsorptionsverfahren zur Anreicherung von polycyclischen aromatischen Kohlenwasserstoffen (=PAK) wird angegeben: nach einer Magnesiumhydroxidfällung in der Wasserprobe wird der Niederschlag abzentrifugiert und durch Zugabe von Ammoniumchlorid gelöst; die organischen Substanzen in dieser Lösung werden mit sehr wenig Cyclohexan extrahiert, wodurch eine Einengung des Extraktes nicht erforderlich ist. Die PAK im Extrakt werden gas-chromatographisch mit ECD-Detektion getrennt. Ein Vergleich dieser neuen Methode mit der “rapid liquid extraction” wird beschrieben.
    Notes: Summary A simple and rapid adsorption method for the enrichment of polycyclic aromatic hydrocarbons (=PAH)is described: after precipitation of magnesium hydroxide in the water sample the precipitate is separated by centrifugation and then dissolved by adding ammonium chloride; the organic substances in this solution are extracted with a very small volume of cyclohexane. A concentration of the extract is not necessary. The PAH in the extract are, separated gaschromatographically using ECD detection. The new method is compared with the “rapid liquid extraction” method.
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 45-46 
    ISSN: 1618-2650
    Keywords: Best. von Barbituraten, Phenytoin in Harn ; Chromatographie, Gas ; Hg-Verbindungen v. Barbituraten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 11-15 
    ISSN: 1618-2650
    Keywords: Best. von Blei neben Wismut ; Chromatographie, Gas ; Di(trifluoräthyl)dithiocarbamat. — Verhalten von Kupfer(II), Nickel(II), Kobalt(III), Eisen(III), Wismut(III), Blei(II), Antimon(III) ; Verteilung zwischen wäßriger Lösung und Chloroform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das Verteilungsverhalten der oben genannten Di(trifluroäthyl)dithiocarbamato-Chelate zwischen wäßrigen Lösungen und Chloroform wird untersucht. Eine Anwendung zur gleichzeitigen gaschromatographischen Bestimmung von Blei und Wismut im ppm-Bereich (0,2–3 ppm) nach Ausschütteln aus wäßrigen Lösungen wird beschrieben (Säule: 5 % GE SE50 auf Gas Chrom Q; 180–240° C; 4°/min; Einspritzblock: 240° C).
    Notes: Summary The solvent extraction of the above di(trifluoroethyl)dithiocarbamatochelates with chloroform is investigated. An application for the simultaneous gas-chromatographic determination 0.2–3 ppm of lead and bismuth after extraction out of aqueous solutions is reported (column: 5% GE SE 50 on Gas Chrom Q; 180–240° C; 4°/min; injection block: 242°C).
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    Cell & tissue research 200 (1979), S. 409-423 
    ISSN: 1432-0878
    Keywords: Human placenta ; Classification of villi ; Histology ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The classification of human placental villi was reviewed on the basis of material prepared by means of special methods. The material from in situ normal-term placentae was biopsied by aspiration into glutaraldehyde. The classification was made on the basis of light-microscopic observations of semithin sections, reconstructions from serial sections, and scanning-electron micrographs. The peripheral villous tree is roughly divided into stem (ramuli), intermediate and terminal villi. The intermediate villi may be further subdivided as mature and immature types, which are found between the stem and terminal villi. Some of the terminal villi possess a local specialization described as the neck region. The histological characteristics and the branching pattern of each type are described, and the basis of the proposed classification is discussed.
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    Cell & tissue research 163 (1975), S. 29-44 
    ISSN: 1432-0878
    Keywords: Spermatozoa ; Capacitation ; Uterus ; Acrosome Reaction ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The surface morphology of rabbit spermatozoa, fixed in situ (female reproductive tract) and prepared for scanning electron microscopy by critical point drying, was studied for as many as 36 hours post coitum. The findings demonstrate that 1) spermatozoa in the reproductive tract following coitus exist as a heterogenous, morphological population and 2) with time, shifts within this population from one predominant morphology to another take place. In the fresh ejaculate, most spermatozoa have intact surfaces free of membranous disruptions. With time, a process of labilization (denudation) of the membranes covering the acrosomal region occurs in a progressively larger proportion of spermatozoa. The labilization originates by a process of vesiculation and/or vacuolation and leads to the appearance of a series of small fenestrations or perforations of the surface membranes. The perforations coalesce, and gradually larger areas of the surface membranes are eroded such that by 15 hours post coitum, the outer acrosomal membrane, as well as other acrosomal areas, are to varying degrees, directly exposed to the uterine milieu. Secretory granules, picked up by cilia and transferred to the spermatozoa become localized over the acrosomal region shortly after coitus. The possible significance of these time-dependent, morphological events with the phenomena of capacitation and the “true” and “false” acrosome reactions are discussed.
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    Cell & tissue research 163 (1975), S. 411-413 
    ISSN: 1432-0878
    Keywords: Cuticle ; Laminae ; Arthropod ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Examination of etched pyramids of decapod crustacean cuticles with the scanning electron microscope indicates that laminae are continuous around the angles of the pyramids. This observation is in direct contrast to the result expected on Bouligand's (1965, 1971) hypothesis and suggests that laminae may be real structures.
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