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  • pharmacokinetics  (96)
  • wheat  (60)
  • Springer  (156)
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wien : Geolog. Bundesanst.
  • 2005-2009
  • 1990-1994  (156)
  • 1992  (156)
Collection
Publisher
  • Springer  (156)
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wien : Geolog. Bundesanst.
  • Wiley-Blackwell  (2)
Years
  • 2005-2009
  • 1990-1994  (156)
Year
  • 1
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    Nutrient cycling in agroecosystems 31 (1992), S. 319-329 
    ISSN: 1573-0867
    Keywords: Superphosphate ; fertilizer effectiveness ; residual value ; lupins ; oats ; wheat ; grain production ; bicarbonate-extractable soil phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a field experiment on a deep pale-yellow sand in a 600 mm per annum rainfall Mediterranean environment of south-western Australia, six levels of phosphorus (P) as superphosphate (O up to 546 kg P ha−1) were applied once only, to the soil surface, before sowing lupins (Lupinus angustifolius). The lupins were grown in a continuous arable cropping rotation with, in successive years, oats (Avena sativa), wheat (Triticum aestivum), lupins. Five such rotations were started in the experiment from 1985 to 1989. The experiment continued until the end of 1990. The relationship between lupin seed (grain) yields and the level of P applied was measured in the year of P application for five successive years (1985 to 1989). The relationship had the same general form but it varied between years, largely due to different maximum yields (yield plateaux) in each year. The residual value of superphosphate applied three years previously was measured for lupins on two occasions (1988 and 1989) relative to superphosphate applied in the current year. The residual values was different in the two years. The superphosphate applied three years previously was about 30% as effective as freshly applied superphosphate in 1988, and 12% as effective in 1989. At each harvest, the relationship between grain yield and the P concentration in the grain differed for different species. However, for each species at each harvest, the relationship was similar regardless of when the P was applied in the previous years. Thus each species had the same internal efficiency of P use curve, and yields varied only with P concentration in tissue. Bicarbonate-extractable soil P was determined on soil samples taken in mid-July of 1989 and 1990. These soil test values were related to grain yields at harvest. The relationship between yield and soil test values had the same general form but varied for different species within years and for each species between years. It also varied for each species within years depending on the year the P was applied.
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  • 2
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    Nutrient cycling in agroecosystems 31 (1992), S. 331-340 
    ISSN: 1573-0867
    Keywords: Superphosphate ; residual value ; wheat ; lupins ; soil test for phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a field experiment on a sandplain soil in a low rainfall (326 mm per annum) Mediterranean environment of south-western Australia, the effectiveness of superphosphate applied in 1986 was measured in three subsequent years relative to freshly-applied superphosphate each year, using grain (seed) yields of wheat (Triticum aestivum) and lupins (Lupinus angustifolius). The wheat and lupins were grown in rotation and both crops were grown each year starting in 1986. Bicarbonate-soluble phosphorus was determined on soil samples taken in mid June from where the P treatment was applied in 1986 only. These soil test values were related to the grain yields produced that year. For each level of superphosphate applied in 1986, soil test values decreased with increasing time from application. The relationship between grain yield and soil test values had the same general form within each year for both plant species, but varied between years. For both species, the effectiveness of superphosphate decreased by about 70–80% between the year of application and the first and second years after application, and by a further approximate 10% in the third year. The relationship between grain yield and the level of superphosphate applied became sigmoidal by 1989.
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  • 3
    ISSN: 1573-0867
    Keywords: nitrogen fertilizer rate ; electroultrafiltration ; wheat ; soil test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of the investigation was to examine whether there exist relationships between the optimum nitrogen fertilizer rate for winter wheat and soil nitrogen fractions extracted by electroultrafiltration (EUF) from autumn samples of the upper soil layer (0–30 cm). Optimum nitrogen fertilizer rates were derived from grain yield curves of field trials carried out with increasing nitrogen fertilizer rates on 19 different sites in 1985/86 and 1986/87. Most soils were luvisols derived from loess, two soils were brown earths and one a pararendzina. Total Nitrogen fertilizer rates were 0, 40, 80, and 120 kg N/ha applied twice before ear emergence. The final nitrogen rate at ear emergence was the same for all treatments, namely 60 kg N/ha. Optimum nitrogen fertilizer rates were derived from the grain yield curve fitted to a modified Mitscherlich equation. The optimum nitrogen fertilizer rates were correlated with the nitrogen fractions extracted by EUF. The regression equation thus obtained showed that NO 3 - , the organic N fraction (EUF Norg), and the EUF Norg-quotient each had a highly significant impact on the optimum nitrogen fertilizer rate. The higher the amounts of EUF-N extracted the lower the optimum nitrogen rate. Substituting the EUF Norg-fraction for total nitrogen concentration in the upper soil layer gave a poorer relationship between the optimum nitrogen fertilizer rate and the soil data. In absolute terms the EUF Norg-fraction had by far the greatest impact on calculating the optimum nitrogen fertilizer rate. The investigation shows that the EUF method is a suitable technique for the determination of available soil nitrogen from which optimum nitrogen fertilizer rates can be derived for winter wheat cultivated under soil and climatic conditions typical for cereal growing areas in central Europe.
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  • 4
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    Nutrient cycling in agroecosystems 31 (1992), S. 43-49 
    ISSN: 1573-0867
    Keywords: Superphosphate ; nitrogen fertilizer ; take-all ; (Gaeumannomyces graminis) ; wheat ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat was grown continuously in soil amended with 5 levels of superphosphate and with 4 levels of urea at 3 sites. The incidence and severity of take-all, caused byGaeumannomyces graminis var.tritici, declined with increasing rates of application of both superphosphate and urea. In both years, the severity of take-all on plants receiving neither superphosphate nor urea was about 40% while at the highest level of superphosphate and urea supply the take-all severity was approximately halved at 22%. There was an increase in grain yield in response to applied superphosphate and urea to the highest level of each nutrient. There was also an increase in the 1,000-kernal weights with superphosphate and urea fertilizer application.
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  • 5
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    Nutrient cycling in agroecosystems 32 (1992), S. 27-36 
    ISSN: 1573-0867
    Keywords: Phosphorus requirement ; wheat ; oats ; barley ; lupins ; triticale ; superphosphate ; grain yield ; phosphorus in grain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The phosphorus (P) requirement for grain production of different crop species (oats (Avena sativa), barley (Hordeum vulgare), triticale (xTriticosecale), narrow-leafed lupins (Lupinus angustifolius), and sandplain lupins (L. cosentinii) was compared with wheat (Triticum aestivum) in five field experiments on different lateritic soils in south-western Australia. Seven or eight levels of superphosphate were applied at the start of each experiment. The amount of P required to produce 70% (four experiments) or 90% (one experiment) of the maximum yield was used to compare P requirements. Large differences in the P requirements of the species were obtained. On P deficient soil in 3 experiments, oats required from 50 to 70% less P than wheat, but required 40% more P on a soil with a long history of superphosphate applications. Compared with wheat, in the year of P application, barley required 50% less P in one experiment, had similar P requirements in two experiments, and required 80% more P in another experiment. In the years after P application, barley required 20% less P in two experiments. On an acidic soil triticale required from 50% to 70% less P than wheat, but on less acidic soil it required 100% more P. In the year of P application, narrow-leafed lupins required 800% more P than wheat in one experiment, and 30% more P in the other experiment. In the year of P application, sandplain lupins required 70% less P than wheat in one experiment.
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  • 6
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    Nutrient cycling in agroecosystems 32 (1992), S. 185-194 
    ISSN: 1573-0867
    Keywords: Residual P ; P fixation ; Bray P ; Olsen P ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nineteen soils from the south east of the Province of Buenos Aires (Argentina) that had been fertilized with moderate amounts of P (10–40 kgP/ha) during the last 10 years were used to investigate the effect of time on the decline of P availability as measured by three soil tests (Bray 1, Bray 2, Olsen) and the null-point method. Differences in rates of P decline among soils and chemical methods were characterized by an exponential coefficient for time (b 2) in equations which describe the changes of the added P retained by the soil (Pr =ac b1 t b2). The rate of decline of P for the nineteen soils calculated for the soil test methods was ordered decreasingly as: null-point 〉 Olsen 〉 Bray 1 〉 Bray 2. The ability of the chemical methods for assessing the residual value of P for wheat growth (RV) was tested in a pot experiment on seven of the soils that differed in their individual rates of reaction with P. Differences between soils in the rate of reaction with P as measured in the laboratory by the null-point method and by the Olsen test were reflected in different residual values for P fertilizer for wheat plants. Thus the value ofb 2 for these methods was well correlated with the observed residual values. The soil properties commonly associated with the retention of P were not related to the value ofb 2 suggesting that more than one soil property may be involved in the measure ofb 2. The exponent for timeb 2 may be used as an index of the ability of the soil test to reflect the decline of P availability with time.
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  • 7
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    European journal of clinical pharmacology 42 (1992), S. 101-105 
    ISSN: 1432-1041
    Keywords: Rufloxacin ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma and urine kinetics of rufloxacin were assessed in healthy volunteers after single (100, 200, 400 and 800 mg) and multiple (300 mg followed by 150 mg daily, Group 1, and 400 mg followed by 200 mg daily, Group 2) oral doses. The kinetics of a single oral dose of 800 mg was assessed in fasting and non-fasting subjects to assess the influence of food intake on drug absorption. The AUCs were 134, 266 and 375 μg · h · ml−1 after 100, 200 and 400 mg, respectively. The AUC after 800 mg p. o. was 715 μg · h · ml −1 in fasting subjects and 614 μg · h · ml−1 in non-fasting subjects. The parameters of the model and the mean renal clearance values indicated some departure from linearity in rufloxacin kinetics. After multiple doses the plasma drug levels during the 6th treatment day were similar to those after the first dose in Group 1 and were about 30–40% higher after the first dose in Group 2. The half-lives after the last dose were much shorter than those estimated in the single dose studies (33–36 h and 50–80 h, respectively).
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  • 8
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    European journal of clinical pharmacology 42 (1992), S. 535-538 
    ISSN: 1432-1041
    Keywords: Meropenem ; Carbapenem ; pharmacokinetics ; uraemia ; haemodialysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of IV meropenem (500 mg over 30 min) has been studied in 6 healthy volunteers and 26 patients with various degrees of renal impairment. Blood samples were taken at different times over 24 h in healthy subjects and 36 to 48 h in uraemic patients, and four or five urine samples were collected over 24 or 48 h. Meropenem concentrations in plasma and urine were measured by a microbiological assay. The mean peak plasma concentration of meropenem ranged from 28 to 40 μg·ml−1 and was not affected by the degree of renal impairment. The terminal half-life of meropenem was approximately 1 h in subjects with normal kidney function and it was proportionately increased as renal function decreased. A significant linear relationship between total body clearance and creatinine clearance as well as between renal clearance and creatinine clearance was observed. The mean apparent volume of distribution at steady state was not significantly altered in uraemic patients. The mean cumulative urinary recovery of meropenem in healthy volunteers was 77% of the administered dose and it was significantly decreased in patients with renal impairment. Haemodialysis shortened the elimination half-life, from 9.7 h during the predialysis period to 1.4 h during the dialysis period. The dose of meropenem should be reduced in relation to the decrease in creatinine clearance.
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  • 9
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    European journal of clinical pharmacology 42 (1992), S. 559-560 
    ISSN: 1432-1041
    Keywords: Mefloquine ; Thai subjects ; pharmacokinetics ; Primaquine ; drug interaction ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
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  • 10
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    European journal of clinical pharmacology 42 (1992), S. 689-691 
    ISSN: 1432-1041
    Keywords: Diphemanil methylsulphate ; pharmacokinetics ; healthy subjects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic parameters of oral diphemanil methylsulphate have been evaluated in six healthy male volunteers. Absorption of the drug was slow (tmax=2 to 4 h), the mean half-life was 8.35 h, and the amount of the drug recovered in urine within 48 h ranged from 0.6 to 7.4% of the administered dose. The results suggest low bioavailability, assuming that the drug is poorly metabolized.
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  • 11
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    European journal of clinical pharmacology 42 (1992), S. 693-694 
    ISSN: 1432-1041
    Keywords: Loperamide ; loperamide oxide ; diarrhoea ; pharmacokinetics ; dose-proportionality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of loperamide, after oral administration of increasing doses (1 to 16 mg) of loperamide oxide, has been investigated in 10 healthy male volunteers, using a randomised cross-over design. Comparison of the maximum plasma loperamide concentration and AUC demonstrated that the bioavailability of loperamide was proportional to the dose of loperamide oxide administered.
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  • 12
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    European journal of clinical pharmacology 43 (1992), S. 67-75 
    ISSN: 1432-1041
    Keywords: Morphine ; Patient-controlled analgesia ; opioids ; pharmacokinetics ; bolus-elimination-transfer ; computer-assisted continuous infusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Bone marrow transplant patients having severe, prolonged oral mucositis pain (expected to last for one to three weeks) used a computer-controlled infusion system to self-administer morphine for pain control. Individual patient pharmacokinetic information, derived from a pretreatment bolus morphine dose, was used in a new bolus-elimination transfer algorithm to produce rapid adjustments of steady plasma morphine concentrations when the patient requested more or less drug. We evaluated the performance characteristics (bias and precision) of this pharmacokinetically based patient-controlled analgesic infusion system (PKPCA) in a group of 15 cancer patients over six to 14 days. Although we found a three- to fivefold pharmaco-kinetic variability in the tailoring morphine dose data, the PKPCA system was free of systematic bias (insignificant overall prediction error) during the patient-controlled infusions in this study population. The absolute prediction error was 19.9% for the group on the first study day and 25.6% over the entire study period (aggregate results; 6–14 days of continuous use). Two-thirds of the patients exhibited no bias throughout the study period, and individual bias in the others was symmetrically distributed (three patients with underpredictions and two overpredicted). Magnitude of prediction error during the patient-controlled morphine infusions was not related to the magnitude of pharmacokinetic deviation of individual subjects from group parameters. Our results indicate that this PKPCA system provides accurate control of plasma morphine concentration when used by patients to self-administer opioid for prolonged pain relief continuously over 1 to 2 weeks. Use of individual pharmacokinetic information, instead of population parameters, may account for superior performance characteristic of this computer-assisted continuous drug infusion system.
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  • 13
    ISSN: 1432-1041
    Keywords: Indomethacin ; steady-state ; pharmacokinetics ; elderly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The steady-state pharmacokinetic profile of indomethacin was examined in twelve healthy volunteers (4 m, 8 f; 20–34 y) and in 12 elderly subjects (7 m, 5 f; 70–88 y). Two formulations of indomethacin were examined, providing duplicate data for each subject group. The subjects received each formulation of indomethacin (25 mg tid) for 6 days in a single blind crossover fashion. On day 7, after an overnight fast, a final 25 mg dose of indomethacin was given and plasma concentrations measured over the following 12 h. Kinetic parameters Cpmin, tmx and AUC (0–12 h) were determined. There were no differences in the pharmacokinetic parameters between young and elderly subjects or between data for the two formulations of indomethacin. AUC values (μg · ml−1 · h), for example, for the two formulations in the young subjects were 5.85 and 6.85 while the values for the elderly subjects were 6.55 and 6.50 respectively. When each treatment period was considered independently there was a significant difference between young and elderly subjects with regard to compliance. The rates of non compliance (over and under compliance) using a capsule count technique were, however, low with a mean maximum value of 5.8% being recorded for the elderly subjects.
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  • 14
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    European journal of clinical pharmacology 42 (1992), S. 231-233 
    ISSN: 1432-1041
    Keywords: Isradipine ; Haemodialysis ; pharmacokinetics ; dialysability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of isradipine, a calcium-channel blocker, have been studied in eight patients on chronic haemodialysis. A single oral dose of 5 mg was administered on both a non-haemodialysis and a haemodialysis day and the plasma concentrations of isradipine were analyzed. The mean cmax, tmax, AUC, and t1/2 in plasma on the non-haemodialysis day were 5.2 ng·ml−1, 1.4 h, 23.8 ng·h·ml−1, and 3.1 h, respectively. The dialysis clearance of isradipine was negligible (5.0 ml·min−1). The t1/2 values during haemodialysis were not significantly different from those observed during the same period post dose on the non-haemodialysis day. The study demonstrates that supplemental doses of isradipine are not necessary in these patients since isradipine is not significantly removed by haemodialysis.
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  • 15
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    European journal of clinical pharmacology 42 (1992), S. 171-174 
    ISSN: 1432-1041
    Keywords: Quinine ; Malaria ; pharmacokinetics ; red blood cells ; plasma ; saliva ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of quinine has been studied in ten healthy adult Africans after intravenous infusion and oral ingestion of a 500 mg dose. Blood and saliva samples were collected over 48 h and quinine in plasma, red cells and saliva was determined by HPLC. Quinine was rapidly and almost completely absorbed after an oral dose, with absorption half-life of 0.53 h, a tmax of 1–3 h and a bioavailability of 88%. Analysis of the i. v. data gave an apparent volume of distribution of 3.6 1·kg−1 and a plasma clearance of 0.19 l·kg−1·h−1. The concentration-time curves for plasma, red cells and saliva had declining phases were approximately parallel, giving a similar half-life that in all three media. The half-lives after the i. v. infusion also did not different from those after oral administration. The dose was well tolerated by both methods of administration.
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  • 16
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    European journal of clinical pharmacology 42 (1992), S. 175-179 
    ISSN: 1432-1041
    Keywords: 2-hydroxy-4-trifluoromethylbenzoic acid (HTB) ; Triflusal ; triflusal metabolite (HTB) ; pharmacokinetics ; protein binding ; ultrafiltration ; binding constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 2-hydroxy-4-trifluoromethylbenzoic acid (HTB) is the main active metabolite of the platelet anti-aggregant drug triflusal. Its binding to plasma proteins of rats and healthy volunteers in vitro and in vivo has been studied. Rats were given a single oral dose of 50 mg·kg−1 triflusal and the healthy volunteers received 300 mg as a single oral dose or a multiple dose regimen of 600 mg every 24 h and 300 mg every 8 h, both for 13 days. Protein-free HTB was obtained by ultrafiltration. Unbound and total HTB concentrations were determined by HPLC. HTB was primarily bound to albumin in plasma. The Scatchard plots suggested two types of binding sites for HTB on the albumin molecule. In rats, the binding constants (K=intrinsic affinity constant, n=number of binding sites) were K1=1.4×105 l·mol−1, n1=1.23, and K2=4.1×103 l·mol−1 and n2=3.77. The mean plasma concentration in rats after oral administration was 185 (37) μg·ml−1 (protein-free HTB: 2.44 (0.77)%). The binding constants in human plasma were K1=4.7×105 l·mol−1, n1=1.93, K2=4.3 l·mol−1 and n2=4.28. The plasma HTB concentration in man (n=8) was 35 μg·ml−1 (Cmax) after a single oral dose of triflusal 300 mg, 172.96 μg·ml−1 (Cmax·ss) during the multiple dosage regimen of 300 mg every 8 h, and 131 μg·ml−1 (Cmax·ss) during the multiple oral dose regimen of 600 mg every 24 h. Unbound HTB ranged from 0.27 to 0.43%, depending on dose. HTB had high affinity for plasma albumin, which was not saturable after therapeutic doses. It showed linear elimination.
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  • 17
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    European journal of clinical pharmacology 42 (1992), S. 181-185 
    ISSN: 1432-1041
    Keywords: Glycerol ; brain oedema ; serum ; cerebrospinal fluid ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Glycerol 50 g infused i. v. over 2 to 6 h is widely used to treat cerebral oedema in patients with acute stroke. Its transit through the blood-cerebrospinal fluid barrier in subjects with uninflamed meninges has now been examined. In 7 patients with an external ventriculostomy for occlusive hydrocephalus, each of whom was given 500 ml of a 10% solution IV over 4 h, serum and CSF were repeatedly sampled during and after the infusion and glycerol was measured enzymatically. The highest serum glycerol level of 191–923 mg/l was observed at the end of the infusion. The maximum CSF glycerol of 18.7–110.8 mg/l was attained 0–1 h after the end of the infusion. Elimination both from serum and CSF approximated a single-exponential decay; the elimination half-life from serum was 0.29–0.56 h compared to 1.03–3.68 h from CSF. In six of the seven cases there was a temporary reversal of the serum/CSF concentration gradient during glycerol elimination. The ratios of the AUCs of CSF and serum, which describe the overall penetration of glycerol into CSF, ranged from 0.09–0.31. In conclusion, the serum level of glycerol produced by giving 50 g IV glycerol over 4 h may not be sufficiently high reliably dehydrate to brain tissue in many patients, and the slow elimination of glycerol from the CSF may be related to the so-called rebound phenomenon.
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  • 18
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    European journal of clinical pharmacology 42 (1992), S. 187-191 
    ISSN: 1432-1041
    Keywords: Dipyrone ; Acetylation phenotype ; metabolism ; pharmacokinetics ; urinary excretion ; metabolite clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The formation and urinary excretion of the dipyrone metabolites, methylaminoantipyrine (MAA), aminoantipyrine (AA), formylaminoantipyrine (FAA) and acetylaminoantipyrine (AAA) were determined following administration of a single oral 1.0 g dose of dipyrone to 12 healthy volunteers. The AAA/AA plasma ratio showed that 3 subjects were slow and 9 were rapid acetylators. Pharmacokinetic parameters were determined separately for each group. A good correlation was found between the plasma and urine AAA/AA ratios. The renal clearance of the four metabolites was similar for both phenotypes. A significant difference in the rate of formation of dipyrone metabolites was found for AA, 0.25 (slow) vs 0.1 ml·min−1·kg−1 (rapid), and for AAA 0.75 (slow) vs 7.53 ml·min−1·kg−1 (rapid). There were comparable differences between slow and rapid acetylators in the AUC and the urinary excretion extrapolated to infinity for AA and AAA. The present results show that the kinetics of dipyrone metabolites in plasma and urine can provide a useful measure of the activity of the enzymes involved in their production.
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  • 19
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    European journal of clinical pharmacology 42 (1992), S. 197-201 
    ISSN: 1432-1041
    Keywords: Digoxin ; Salbutamol ; serum ; skeletal muscle digoxin ; pharmacokinetics ; drug interaction ; serum potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A single dose of the β2-adrenoceptor agonist salbutamol has previously been shown to decrease serum digoxin concentration in healthy volunteers. A possible explanation of the phenomenon is a β2-adrenoceptor-mediated increase in the specific binding of digoxin to skeletal muscle. The present study was undertaken to further elucidate the effect of salbutamol on the pharmacokinetics of digoxin in man. Nine volunteers were studied on two occasions during salbutamol or placebo treatment. On test days salbutamol, 4 μg·kg−1·h−1 or saline was infused for 10 h, preceded and followed by four and three days, respectively, of oral administration. A single i. v. injection of digoxin 15 μg·kg−1, was given 20 min after starting the infusion. At the end of the infusion a muscle biopsy was taken from the vastus lateralis. Blood samples for the analysis of serum digoxin and potassium were repeatedly taken over 72 h. Urine was collected over a period of 24 h for determination of the renal excretion of digoxin and potassium. The serum digoxin concentration, expressed as the AUC 0–6 h was 15% lower during salbutamol infusion than during saline infusion. Salbutamol caused significantly faster elimination of digoxin from the central volume of distribution to deeper compartments. Salbutamol had no effect on the renal clearance of digoxin. The skeletal muscle digoxin concentration tended to be higher (48%) during salbutamol compared to placebo treatment. The serum potassium concentration was significantly lower after salbutamol compared to placebo, as was the rate of renal excretion of potassium. The results support the hypothesis that the salbutamol-induced decrease in serum digoxin is caused by increased distribution of digoxin to skeletal muscle (and possibly other tissues), and that this may be secondary to a β2-adrenoceptor-mediated increase in Na-K-ATPase activity.
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  • 20
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    European journal of clinical pharmacology 42 (1992), S. 203-207 
    ISSN: 1432-1041
    Keywords: Nicorandil ; pharmacokinetics ; angina pectoris ; uraemia ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of oral nicorandil 20 mg 12 hourly for 9 doses was evaluated in 21 hospitalized patients with angina pectoris due to coronary heart disease and with normal and impaired renal function. Patients were divided into 3 groups based on creatinine clearance (CLCr): GROUP I (n=6) 〉 80 ml/min, GROUP II (n=8) 20–80 ml/min, and GROUP III (n=7) 〈 20 ml/min. After the first dose, the total clearance of nicorandil (CL) value did not change with increasing renal failure and so was not dependent on creatinine clearance. After the last dose CL was 51 l·h−1 in Group I, 44 l·h−1 in Group II and 56 l·h−1 in Group III, and it was not related to creatinine clearance. The percentage of the dose excreted in the urine was 0.4%. No significant difference was noted in any of the other pharmacokinetic parameters examined in the three groups, not even on comparing values obtained on the first and last days of treatment. The findings suggest that there is no need to change the dose of nicorandil in subjects with different degrees of renal failure.
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  • 21
    ISSN: 1432-1041
    Keywords: Alprazolam ; benzodiazepines ; pharmacokinetics ; pharmacodynamics ; sublingual dosage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We gave 12 healthy male volunteers 1 mg of alprazolam or placebo on three occasions after a standard breakfast in a double-blind, randomized, single-dose, three-way crossover study. The three trials were: (a) oral alprazolam and sublingual placebo; (b) oral placebo and sublingual alprazolam; (c) placebo by both routes. Plasma alprazolam concentrations during 24 h after each dose were measured by electron-capture gas-liquid chromatography. Peak plasma concentrations were reached later after sublingual than oral dosage (2.8 vs 1.8 h, P〈0.01). Other kinetic variables were not significantly different: peak plasma concentration, 11.3 vs 12.0 ng·ml−1; elimination half-life, 12.5 vs 11.7 h; and total area under the plasma concentration versus time curve, 197 vs 186 h·ng·ml−1. Pharmacodynamic measures showed that sublingual and oral alprazolam both produced sedation, fatigue, impaired digit symbol substitution, slowing of reaction time, and impairment of the acquisition and recall of information. These changes were initially observed at 0.5 h after dosage and lasted up to 8 h. In general the two routes were significantly different from placebo but not from each other.
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  • 22
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    European journal of clinical pharmacology 42 (1992), S. 445-448 
    ISSN: 1432-1041
    Keywords: Ethanol ; whole blood ; plasma ; total body water ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of ethanol in plasma and whole blood have been investigated and the results used to estimate the volume of total body water (TBW) by means of the dilution principle. Fifteen men (mean age 62 y) were given 0.6 g ethanol/kg body weight as an intravenous infusion over 1 h. The peak concentration of ethanol in plasma was 120 mg·dl−1 compared to 108 mg·dl−1 for whole blood. The disappearance rate of ethanol from plasma was 18.6 mg·dl−1·h−1 compared to 17.0 mg·dl−1·h−1 for the whole blood concentration-time data. The apparent volume of distribution of ethanol (Vz) was 0.54 l·kg−1 according to plasma kinetics compared to 0.59 l·kg−1 for the kinetics derived from whole blood. The mean area under the curve (AUC) was 294 mg·dl−1×h for plasma kinetics compared to 266 mg·dl−1×h for whole blood. The TBW was 40.9 l or 50.9% of body weight for the plasma concentration-time data. This agreed well with the 40.3 l or 50.1% of body weight obtained using whole blood.
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  • 23
    ISSN: 1432-1041
    Keywords: Methylprednisolone ; Rheumatoid arthritis ; bioavailability ; pharmacokinetics ; clinical response ; pulse steroid therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A commercially available 1.0 g intravenous (i.v.) dosage formulation of methylprednisolone, as the sodium hemisuccinate salt (Solu MedrolR, Upjohn) was administered both parenterally and orally (pulse steroid therapy) on separate occasions, to eight elderly (mean 65 y) patients with active rheumatoid arthritis. The relative oral bioavailability of the sterol was 69.2%. Elimination of methylprednisolone was prolonged when given orally; the mean residence times were 7.23 h and 3.94 h for oral and i.v. administrations, respectively. Clinical response to pulse steroid therapy was no different with respect to route of administration. There were no significant differences in standard clinical and laboratory assessments of disease activity when the two therapies were compared. Oral administration of methylprednisolone in patients requiring high-dose pulse steroid therapy is convenient and avoids the discomfort and inconvenience associated with i.v. administration.
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  • 24
    ISSN: 1432-1041
    Keywords: Acetyl-L-carnitine ; Senile Dementia of Alzheimer Type ; pharmacokinetics ; plasma concentration ; cerebrospinal fluid concentration ; carnitine metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Acetyl-L-carnitine (ALC), a physiological component of the L-carnitine family, has been proposed for treating Alzheimer's disease in pharmacological doses. As this condition requires prolonged therapy, its kinetics has been examined after a multiple dose regimen, involving different routes of administration, in 11 patients suffering from Senile Dementia of Alzheimer Type. The study design comprised a 3-day basal observation period, sham treatment with repeated blood sampling; treatment with 30 mg·kg−1 i.v. given twice for 10 days (plasma kinetics was studied on the 7th day), and 50 days of 2.0 g/day p.o. given in three daily doses. Total acid soluble L-carnitine, L-carnitine and acetyl-L-carnitine in plasma and CSF were evaluated using an enantioselective radioenzyme assay. Short chain L-carnitine esters were calculated as the difference between total and free-L-carnitine. The plasma concentrations of individual components of the L-carnitine family did not change during the three days of the basal period, nor were they affected during the sham therapy period. Following the i.v. bolus injections, the plasma concentrations showed a biphasic curve, with average t1/2 of 0.073 h and 1.73 h, respectively. At the end of oral treatment, plasma acetyl-L-carnitine and L-carnitine short chain esters were significantly higher than during the run-in phase. The CSF concentrations paralleled those in plasma, suggesting that ALC easily crosses the blood-brain barrier. It is concluded that i.v. and oral administration of multiple doses of ALC can increase its plasma and CSF concentration in patients suffering from Alzheimer's disease.
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  • 25
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    European journal of clinical pharmacology 42 (1992), S. 95-99 
    ISSN: 1432-1041
    Keywords: Ofloxacin ; Haemodialysis ; ofloxacin metabolites ; pharmacokinetics ; multiple doses ; dosage selection ; renal failure ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 7 patients with end-stage renal disease on regular haemodialysis were treated orally with a loading dose of 200 mg ofloxacin and multiple maintenance doses of 100 mg per 24 h for 10 days. The pharmacokinetics of ofloxacin and its metabolites were studied at the end of the treatment period. Plasma and dialysate concentrations of ofloxacin and ofloxacin metabolites were measured by HPLC. Peak (3.1 mg·1−1) and trough levels (1.6 mg·1−1) and the AUC of ofloxacin were comparable to the values in healthy volunteers given 300 to 400 mg ofloxacin p.o. The mean half-life, determined in the dialysis-free interval (t1/2β) and during the haemodialysis session (t1/2HD), was 38.5 h and 9.9 h, respectively. Extrarenal clearance (32.7 ml·min−1) was unchanged as compared to that reported in healthy volunteers after a single dose of ofloxacin. The fractional removal by haemodialysis amounted to 21.5%. Two metabolites, ofloxacin-N-oxide and demethyl-ofloxacin, were detected in plasma. Despite prolonged t1/2β of both metabolites (66.1 and 50.9 h) and multiple doses of ofloxacin the peak concentrations of the metabolites reached only 14% and 5% of that of the parent drug, respectively. It is concluded that in patients on regular haemodialysis treatment the dosage adjustment employed resulted in safe and therapeutically favourable plasma concentrations. The observed accumulation of ofloxacin metabolites does not appear to have any toxic or therapeutic significance.
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  • 26
    ISSN: 1432-1041
    Keywords: Methotrexate ; non-steroidal anti-inflammatory drugs (NSAIDs) ; interaction ; disposition ; adverse effects ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have studied the pharmacokinetics of methotrexate in patients with rheumatoid arthritis concurrently treated with choline magnesium trisalicylate, ibuprofen, naproxen, or a non-NSAID analgesic (control treatment). The apparent systemic clearance of methotrexate was significantly reduced by all three treatments. Trisalicylate and ibuprofen both significantly reduced methotrexate renal clearance, but only the trisalicylate significantly displaced methotrexate from protein, increasing the fraction unbound by 28%. These data show that NSAIDs can affect the disposition of methotrexate, possibly increasing the potential for toxicity and necessitating dosage adjustments. However, large inter-subject variability precludes specific dosage recommendations.
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  • 27
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    European journal of clinical pharmacology 43 (1992), S. 567-569 
    ISSN: 1432-1041
    Keywords: Mefloquine ; Tetracycline ; Thai subjects ; Thai subjects ; drug interaction ; pharmacokinetics ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of a single oral dose of mefloquine given either alone or with tetracycline has been studied in 20 healthy Thai male volunteers. There was a significantly higher maximum whole blood mefloquine concentration after coadministration with tetracycline (1600 vs 1160 ng · ml−1), as well as a significantly reduced terminal half-life (14.4 vs 19.3 days), mean residence time (11.9 vs 16.0 days) and volume of distribution at steady state (13.3 vs 19.91 · kg−1). Although there was no significant change in the AUC from zero time to infinity, the AUC from zero time to 7 days was significantly increased by tetracycline (6.18 vs 4.76 μg · ml−1 · day). The changes in mefloquine disposition after tetracycline treatment are probably due to a reduction in enterohepatic recycling. The initial increase in mefloquine AUC without an apparent increase in side-effects suggests that this combination may have a place in the treatment of multi-drug resistant falciparum malaria.
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  • 28
    ISSN: 1432-1041
    Keywords: Cyclosporine ; Hyperlipidaemia ; heart transplantation ; fenofibrate ; fenofibric acid ; pharmacokinetics ; drug interaction ; nephrotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Cyclosporine (Cy) binds to lipoproteins in plasma. In order to test if its pharmacokinetics would be modified when efficient lipid-lowering treatment is introduced, a study has been done of Cy pharmacokinetics and any interaction with the lipid-lowering agent fenofibrate in hyperlipidaemic long-term, survivors of heart transplantation. Fenofibrate 200 mg once daily significantly reduced blood lipids (cholesterol 6.5 vs 7.7 mmol/l; apoprotein B 1.2 vs 1.6 g/l) but did not modify mean whole blood Cy trough levels (113 before fenofibrate vs 103 ng·ml−1), Cmax (812 ng·ml−1 by RIA and 757 ng·ml−1 by HPLC before fenofibrate versus 865 and 741 respectively, during fenofibrate); tmax (1.6 and 1.7 h before fenofibrate versus 1.4 and 1.4 h respectively), and t1/2 (13.9 and 11.1 h versus 9.5 and 10.7 h). The only adverse effect was an increase in creatinine (157 vs 145 mmol/l). Further studies are needed to investigate the mechanism of Cy-fenofibrate nephrotoxicity and to evaluate the long-term efficiency and safety of fenofibrate after heart transplantation.
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  • 29
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    European journal of clinical pharmacology 42 (1992), S. 219-222 
    ISSN: 1432-1041
    Keywords: Thiamine ; pharmacokinetics ; analytical method ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A novel liquid chromatographic method for the determination of thiamine in plasma has been developed and has been used to study plasma thiamine concentrations after multiple dosage regimens for 11 days. The method involves purification, concentration and analytical separation of thiochrome on-line, using a switching column system. Ten healthy men were given 500 mg thiamine i.m. once a day (Group 1) and ten were given 250 mg p.o. every 12 h (Group 2). The times to reach steady state (7 and 5.6 days for Groups 1 and 2, respectively) were not different (P〉0.05). The mean elimination half-life was 1.8 days. The mean minimum steady-state concentration after the oral regimen (23 μg·l−1) was 78% of that after the intramuscular regime (29 μg·l−1).
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  • 30
    ISSN: 1432-1041
    Keywords: Ibopamine ; Isosorbide-5-mononitrate ; pharmacokinetics ; drug interaction ; healthy volunteers ; pharmacodynamics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The possibility of a pharmacokinetic interaction between isosorbide-5-mononitrate (5-ISMN) and epinine, the active metabolite of ibopamine, has been investigated in 8 healthy male subjects given single doses of 200 mg ibopamine and 20 mg 5-ISMN, separately and together. The plasma 5-ISMN concentration-time profile was the same whether 5-ISMN was administered concomitantly with ibopamine or alone [AUC(o-t): 2.24 μg·ml−1·h after 5-ISMN alone, 2.16 μg·ml−1·h after 5-ISMN + ibopamine]. The plasma concentrations of total and free epinine and the urinary recovery of total epinine, homovanillic acid and dihydroxyphenylacetic acid, too, were not different when ibopamine was administered alone or concomitantly with 5-ISMN. The intake of ibopamine did not change the blood pressure and heart rate. The decrease in diastolic blood pressure induced by 5-ISMN was not influenced by concomitant intake of ibopamine. The observations suggest that in healthy volunteers there is no pharmacokinetic interaction between 5-ISMN and ibopamine.
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  • 31
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    European journal of clinical pharmacology 42 (1992), S. 593-598 
    ISSN: 1432-1041
    Keywords: Metamizole ; Furosemide ; prostaglandins ; drug interaction ; adverse effects ; pharmacokinetics ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic and pharmacodynamic interactions between metamizole (dipyrone) and furosemide were investigated in 9 of 12 healthy female subjects able to complete the study. They received oral metamizole 3×1 g for 3 days or placebo (cross-over) and on the last day of both study periods furosemide 20 mg IV. On the last two days a balanced sodium diet (120 mEq) and on Day 3 an oral water load (600 ml) were given. Metamizole significantly inhibited basal urine flow, whereas the fractional excretion of sodium and chloride and the 12 h-GFR remained unchanged. Metamizole significantly reduced furosemide clearance (175 vs 141 ml · min−1), furosemide-stimulated plasma renin activity (1.42 vs 0.79 ng AI · ml−1 · h−1) and the urinary excretion of prostacyclin metabolites and of prostaglandin F2α (by 70–81%). The renal clearance and terminal half-life of furosemide, peak renal chloride and volume excretion were unchanged. Thus, metamizole did not interact with the renal excretion and the diuretic effect of furosemide, although prostaglandin synthesis was significantly reduced.
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  • 32
    ISSN: 1432-1041
    Keywords: 6-Mercaptopurine ; suppository ; bioavailability ; acute lymphoblastic leukaemia ; children ; interindividual variability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma levels and the area under the plasma concentration-time curve (AUC) values of 6-mercaptopurine (6-MP) were determined in a balanced crossover study of oral (powder) and rectal (macrogol suppository) administration to 5 children with acute lymphoblastic leukaemia (ALL). The AUC (538.6 ng · h · ml−1) after the rectal dose of 30 mg/m2 was approximately 1.5-times of that (365.5 ng · h · ml−1) after the oral dose of 87.5 mg/m2. The coefficients of variation of interindividual variability of the AUCs were 21.5% and 32.3%, respectively. The relative bioavailability of the macrogol suppository compared to the powder was approximately 4.39. These findings indicate that rectal administration of 6-MP could avoid the first-pass effect of this drug in the alimentary canal and/or liver, resulting in a large AUC of 6-MP, and so could reduce interindividual variability in plasma 6-MP concentrations. Rectal administration of 6-MP may be more effective than empirical oral dosing for the treatment of children with ALL, especially for patients with nausea and/or vomiting.
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  • 33
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    European journal of clinical pharmacology 42 (1992), S. 635-639 
    ISSN: 1432-1041
    Keywords: Vancomycin ; Haemodialysis ; highflux membranes ; pharmacokinetics ; renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Vancomycin is usually given only once a week to haemodialysis (HD) patients. If highly permeable dialysis membranes are used, however, high clearance values have been reported, so the aim of the study was to determine whether high clearance of vancomycin resulted in sufficient drug elimination to induce subtherapeutic plasma levels after one week. In 18 chronic HD patients, treated with polysulfone dialyzers (1.2 m2), the pharmacokinetics of vancomycin were studied after administration of 1 g. Concentrations were determined by fluorescence polarisation immunoassay. At a blood flow of 219 ml·min−1, HD clearance of vancomycin was 62.3 ml·min−1. Immediately after dialysis plasma concentrations were 38% lower than predialysis levels. However, marked rebound in the vancomycin level was observed 5 h later, resulting in plasma levels only 16% lower than prior to dialysis. 3 HD treatments in 1 week removed about one third of the initial dose. After one week 15 of 18 patients still had a therapeutic plasma level (〉5 μg·ml−1). In conclusion, polysulfone membranes show high clearance of vancomycin. However, transfer of drug from blood to dialysate appears to be faster than from tissues to blood. Because of a marked rebound in plasma level after treatment, therapeutic drug concentrations will still be present in most patients after one week.
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  • 34
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    European journal of clinical pharmacology 43 (1992), S. 501-505 
    ISSN: 1432-1041
    Keywords: S-1452 ; thromboxane A2 receptor antagonist ; nocturnal dosage ; platelet aggregation ; circadian rhythm ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary It is well known that platelet aggregation shows a morning rise, which may contribute to the increase in the onset of ischaemic heart diseases during the morning period. The present study was undertaken to determine whether nocturnal dosage with S-1452, a thromboxane AZ receptor antagonist, would blunt the morning rise in platelet aggregability. S-1452 50 mg or placebo were given orally to 8 healthy subjects at 10.00 h (day trial) or 22.00 h (night trial) according to a cross-over design. Plasma concentrations of S-1452 and its metabolites, bisnor-( + )-S-145 and tetranor-(+ )-S-145, and platelet aggregation were determined during the 12-hour period following the dose. Mean plasma concentrations of S-1452, bisnor-( + )-S-145 and tetranor-(+ )-S-145 during the absorption phase were lower after the nocturnal dose than after the morning dose. The maximum plasma concentration and area under the plasma concentration-time curve of the compounds were also lower and the time to the maximum concentration were delayed after the treatment at night. A morning rise in platelet aggregation was observed following placebo treatment. The inhibitory effect of S-1452 on platelet aggregation was observed at 3 hours and persisted for up to 9 h in both trials. The results suggest that S-1452 is absorbed more slowly after the nocturnal dose than after the morning dose. However nocturnal treatment with 50 mg S-1452 may blunt the morning rise in platelet aggregability.
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  • 35
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    European journal of clinical pharmacology 43 (1992), S. 527-531 
    ISSN: 1432-1041
    Keywords: Calcitonin ; Colonic administration ; Bioavailability ; pharmacokinetics ; pharmacodynamics ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Human calcitonin (hCT) injected into the lumen of the descending colon of normal human subjects was absorbed within minutes and could be recognized intact in plasma as shown by RIA in combination with reverse-phase HPLC. The absorption was low and variable, with bioavailabilities ranging from 0.01% to 2.7% relative to intravenously administered hCT (area under the concentrationtime curve). With intravenous hCT serum calcium was lowered and the fractional urinary excretion of calcium, phosphorus, sodium and chloride was significantly stimulated. With the intracolonic hCT, the fractional urinary excretions of calcium, sodium and chloride were also marginally stimulated relative to intracolonic vehicle (placebo). In conclusion, hCT is absorbed intact from the colon, but the bioavailability is low and highly variable.
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  • 36
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    European journal of clinical pharmacology 43 (1992), S. 85-88 
    ISSN: 1432-1041
    Keywords: Hypertension ; Carvedilol ; chronic renal failure ; pharmacokinetics ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic and acute systemic haemodynamic effects of a single oral dose of 50 mg carvedilol has been studied in 24 hypertensive patients with chronic renal failure. The patients were stratified into 3 groups according to the creatinine clearance: I 51–90 ml · min−1; II 26–50 ml · min−1; III 4–25 ml · min−1. The area under plasma level time curve AUC, the elimination half-life t/12, the maximum plasma concentration Cmax, the time to peak concentration tmax were not significantly different between groups, whereas the amount of unchanged drug or metabolite excreted in urine Ae and the renal clearance CLR of carvedilol and its metabolites M2, M4, M5 were significantly decreased in Group III. Blood pressure and heart rate decreased in all 3 groups of patients after acute administration of 50 mg carvedilol. Mild adverse effects were reported in 6 patients. Despite a decrease in the renal clearance of carvedilol and of its metabolites with decreasing kidney function, its main pharmacokinetic parameters remained unchanged. The present results suggest that the dose of carvedilol need not be reduced in hypertensive patients with chronic renal failure.
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  • 37
    ISSN: 1432-1041
    Keywords: Tiopronin ; 2-mercaptopropionic acid ; pharmacokinetics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have studied the pharmacokinetics of tiopronin and its principal metabolite, 2-mercaptopropionic acid (2-MPA) in healthy volunteers after the oral administration of 500 mg (2 Acadione® tablets), followed by simultaneous assay of the two compounds in plasma over a period of 48 h using a new method (emission of fluorescence after HPLC and post-column derivatization by pyrene-maleimide). The absorption of tiopronin was slow (tmax between 4 and 6 h) and the plasma concentrations subsequently fell biexponentially. The principal metabolite 2-MPA appeared later in the plasma (tmax between 10 and 12 h after a lag-time of 3 h) then disappeared monoexponentially. About 15% of the tiopronin was metabolized to 2-MPA.
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  • 38
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    European journal of clinical pharmacology 42 (1992), S. 209-212 
    ISSN: 1432-1041
    Keywords: Ethanol ; gastric acid inhibition ; pharmacokinetics ; antisecretory drugs ; omeprazole ; ranitidine ; cimetidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of three gastric antisecretory drugs on the pharmacokinetics of ethanol have been studied in a randomized crossover experiment. Male medical students (n=12) took ethanol 0.8 g/kg body weight at 08.00 h after an overnight fast. On seven successive days before drinking ethanol they were given omeprazole 20 mg, cimetidine 800 mg, ranitidine 300 mg, or no drug, with a period of at least 7 days between treatments. The peak blood ethanol concentration of 21.9 to 22.8 mmol·l−1 occurred at 64 to 70 min after the end of drinking. The rate of disappearance of ethanol from the blood ranged from 3.0 to 3.3 mmol·l−1·h−1 and the rate of removal from the whole body ranged from 8.0 to 8.5 g·h−1. The apparent volume of distribution of ethanol was almost the same for all four treatments: mean 0.68 l·kg−1, corresponding to a mean total body water of 441 (59% body weight). Mean areas under the concentration-time profiles of ethanol ranged from 83 to 87 mmol·l−1·h for the four treatments. It is concluded that omeprazole, cimetidine and ranitidine do not alter the kinetics of a moderate dose of ethanol.
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  • 39
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    European journal of clinical pharmacology 42 (1992), S. 227-229 
    ISSN: 1432-1041
    Keywords: Tenoxicam ; Warfarin ; drug interaction ; pharmacokinetics ; anticoagulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of tenoxicam on plasma warfarin concentrations and on its anticoagulant effect has been studied in healthy volunteers. Tenoxicam did not alter the plasma warfarin concentration versus time profile. Treatment with it for 14 days had no effect on the average dose of warfarin required to maintain the prothrombin time within a specified range. The coumarin dose index, an indicator of warfarin sensitivity, remained unchanged during tenoxicam administration. The results demonstrate the lack of a clinically relevant effect of tenoxicam on warfarin-induced anticoagulation.
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  • 40
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    European journal of clinical pharmacology 43 (1992), S. 173-177 
    ISSN: 1432-1041
    Keywords: Enalapril ; Hydrochlorothiazide ; pharmacokinetics ; renal impairment ; old patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a randomized, cross-over, single-dose study of 19 elderly hypertensive patients (aged 62–84 y, SBP 〉 160 mm Hg, DBP 〉 100 mm Hg, creatinine clearance 11–93 ml·min−1) we have studied the pharmacokinetics of the angiotensin converting enzyme (ACE) inhibitor enalapril after a single oral dose of either 10 mg enalapril or 10 mg enalapril + 25 mg hydrochlorothiazide. The pharmacokinetics of enalapril were unaffected by hydrochlorothiazide, but there was a significant reduction in renal clearance and a significant increase in AUC(0–24 h) of enalaprilat after hydrochlorothiazide, resulting in higher serum concentrations of the active drug. This was independent of the individual degree of renal impairment and might be due either to an initial reduction of GFR by hydrochlorothiazide or to interference with the tubular secretion of enalaprilat. The relationships between serum enalaprilat and serum ACE activity were similar after both treatments, both consistent with a value for Ki of enalaprilat of about 0.1 nmol·l−1. Thus, serum ACE activity was not affected by hydrochlorothiazide but completely reflected the pharmacokinetics of enalaprilat in both treatments.
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  • 41
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    European journal of clinical pharmacology 43 (1992), S. 179-184 
    ISSN: 1432-1041
    Keywords: Ebastine ; Ethanol interaction ; carebastine ; psychomotor performance ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have given 12 healthy subjects the H1-antihistamine ebastine (20 mg) or placebo in a double-blind, crossover study for one week each. The subjects were tested for drug effects on Day 6 of each period, and for interactions of ebastine with ethanol (0.8 g·kg−1) on Day 7. On both days, the testing runs were done at baseline and at 2, 4, and 6 h after the drug. Performance was evaluated both objectively (digit symbol substitution, flicker fusion, Maddox wing, nystagmus, simulated driving, body balance) and subjectively (visual analogue scales) and with questionnaires. Venous blood samples were taken daily during maintenance and during each test run for assay of plasma carebastine. Blood ethanol concentrations were assayed with an Alcolmeter in the breath and directly in the blood. Plasma carebastine concentration reached a steady-state from Day 3 on; the mean concentrations in the morning were 92 µg·l−1 on Day 6 and 104 µg·l−1 on Day 7. The rise in plasma carebastine after an extra 20 mg of ebastine was accelerated but not increased by ethanol. Ebastine did not impair performance objectively or subjectively. It slightly improved body balance and reduced errors during simple tracking at 4 h. Blood ethanol concentrations peaked (mean 0.76 g·l−1) at 1.5 h after ethanol intake. Ethanol impaired performance in most objective tests and produced clumsiness, muzziness, and mental slowness, but little drowsiness. Ebastine neither modified the blood ethanol concentrations nor increased the effects of ethanol. We conclude that treatment with 20 mg ebastine once daily for one week provides steady concentrations of carebastine in plasma without impairment of skilled performance or important interactions with alcohol.
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  • 42
    ISSN: 1432-1041
    Keywords: β-Methyldigoxin ; Ranitidine ; pharmacokinetics ; drug interaction
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  • 43
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    European journal of clinical pharmacology 43 (1992), S. 197-199 
    ISSN: 1432-1041
    Keywords: Tenoxicam ; pharmacokinetics ; haemodialysis ; end-stage renal disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have studied the pharmacokinetics of tenoxicam after single and multiple oral doses of 20 mg in five patients (2 men and 3 women) with end-stage renal disease undergoing haemodialysis. After a single dose, tenoxicam had a half-life (t1/2) of 33 h, an apparent clearance (CL·f−1) of 4.3 ml·min−1, and an apparent volume of distribution (Vz·f−1) of 11.8 l. The maximum tenoxicam concentration (Cmax) was 4.3 mg·l−1 at a median tmax of 1.7 h. There were no significant differences between the values calculated from the pre- or post-dialyser port plasma samples. Tenoxicam plasma concentrations measured during once daily dosing before and after haemodialysis showed that tenoxicam does not accumulate. Our findings suggest that dosage adjustment may not be required in patients with end-stage renal disease on haemodialysis taking tenoxicam.
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  • 44
    ISSN: 1432-1041
    Keywords: Noradrenaline ; Adrenaline ; catecholamines ; pharmacokinetics ; healthy volunteers ; IV infusion
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Noradrenaline and adrenaline were infused IV at 5 different rates (0.01–0.2 μg · kg · min− for 30 min to volunteers. The plasma catecholamine concentrations were determined by HPLC and electro-chemical detection. At the highest infusion rate, the arterial and venous plasma concentrations of noradrenaline increased from 1.18 to 44.1 nmol · l−1and from 1.14 to 31.9 nmol · l−1, respectively, and of adrenaline from 0.29 to 23.9 nmol · l−1 and from 0.28 to 19.3 nmol · l−1 respectively. The peripheral venous plasma concentration of noradrenaline averaged 76% of the arterial concentration, and of adrenaline it was 73%. There was a linear relationship between the peripheral venous and arterial plasma noradrenaline and adrenaline concentrations at therapeutic doses.
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  • 45
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    European journal of clinical pharmacology 43 (1992), S. 273-276 
    ISSN: 1432-1041
    Keywords: Molsidomine ; slow release ; pharmacokinetics ; in vitro/in vivo correlation ; pharmacokinetics ; healthy volunteers ; dissolution profile
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A novel slow release preparation containing 24 mg molsidomine has been investigated in 6 healthy subjects. Individual concentration/time-profiles after the tablet showed two separate concentration peaks at 2.2 h and 15.0 h. The relative bioavailability of the slow release preparation in comparison to an aqueous solution of molsidomine was 0.67. The in vivo dissolution profile revealed either a progressive decrease in dissolution velocity caused by altered physico-chemical conditions in the ileum and the colon or a progressive reduction in the absorption constant. In all subjects deconvolution revealed a punctual increase in absorption about 15 h post-dose, coinciding with the second peak of the concentration/time-profile. Therapeutic plasma levels of molsidomine (〉 5 ng · ml−1 were not maintained over 24 h by this slow release formulation.
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  • 46
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    European journal of clinical pharmacology 43 (1992), S. 445-447 
    ISSN: 1432-1041
    Keywords: Captopril ; Digitoxin ; impedance cardiography ; drug interaction ; healthy volunteers ; pharmacodynamics ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The chronic oral administration of 0.07 mg digitoxin o. d. for up to 58 days to 12 healthy volunteers caused a small drop in mean heart rate HR (95 % CI: −7.9 to −1.6 beats · min−1), in mean diastolic blood pressure (95 % CI: −8.3 to −0.4 mm Hg), shortening of the QTc-interval (95 % CI: −42 to −19 ms), shortening of the HR-corrected pre-ejection period PEPc (95 % CI: −16 to −1 ms) and electromechanical systole QS2c (95 % CI: −25 to −1 ms), and an increase in the impedance cardiographic Heather index (dZ/dtmax/RZ, 95 % CI: 0.3 to 4.3) relative to the baseline measurements before digitalisation. The concomitant administration of 25 mg oral captopril b. d. did not significantly alter these responses relative to the concomitant double-blind administration of placebo, nor did it alter the pharmacokinetic characteristics of plasma digitoxin at steady state. Thus, no relevant change in the pharmacokinetic and pharmacodynamic characteristics of chronically administered digitoxin were induced by concomitant treatment with captopril.
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  • 47
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    European journal of clinical pharmacology 42 (1992), S. 237-256 
    ISSN: 1432-1041
    Keywords: Non-steroidal anti-inflammatory drugs ; Enantioselective ; Enantiomers ; pharmacodynamics ; pharmacokinetics ; stereoselective
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  • 48
    ISSN: 1432-1041
    Keywords: Dihydropyridine ; Felodipine ; availability ; flavonoids ; dietary interaction ; pharmacokinetics ; pharmacodynamics ; adverse effects
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of drinking grapefruit juice on the acute pharmacokinetic and haemodynamic actions of the dihydropyridine calcium antagonist felodipine given as a 5 mg plain tablet has been studied in nine, healthy, middle-aged males. Compared to water, grapefruit juice caused an increase in Cmax from mean 6 to 16 nmol · l−1, and in the AUC from 23 to 65 nmol · h · l−1. The change in AUC corresponded to an increase in the systemic availability of felodipine from 15 to 45%, assuming no change in its clearance. This change was probably caused by inhibition of the oxidation of felodipine to the inactive dehydrofelodipine by flavonoids in grapefruit juice. The interaction with grapefruit juice is believed to be a class effect for the dihydropyridines, as oxidation of the dihydropyridine ring to the corresponding pyridine derivative is a major metabolic route for all these drugs. The higher plasma concentrations of felodipine taken with grapefruit juice resulted in a greater change in blood pressure measured in the morning 3 h after dosing (−9%) than did water (0%).
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  • 49
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    European journal of clinical pharmacology 42 (1992), S. 329-332 
    ISSN: 1432-1041
    Keywords: Midazolam ; Fentanyl ; Neonates ; pharmacokinetics ; sedation drug interaction ; hypotension
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Midazolam is a water soluble benzodiazepine, with a short elimination half-life in adults and children. An IV bolus (0.2 mg·kg−1) immediately followed by continuous infusion of 0.06 mg·kg−1·h−1 was administered to 15 critically ill neonates at a gestational age of 32.8 weeks, who required sedation for mechanical ventilation. Heart rate and blood pressure were closely monitored. Hypotension occurred in 4 patients after the bolus dose or during the continuous infusion. Three of them had also been given fentanyl. Individual pharmacokinetic parameters were calculated: plasma clearance was 3.9 ml·min−1, elimination half-life was 12.0 h. Because of its short half-life compared to diazepam, midazolam may be used during the neonatal period to achieve rapid, brief sedation. However, it should be administered cautiously to neonates, particularly in premature infants, or if fentanyl is also given.
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  • 50
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    European journal of clinical pharmacology 42 (1992), S. 343-345 
    ISSN: 1432-1041
    Keywords: Omeprazole ; Theophylline ; pharmacokinetics ; drug interaction
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of omeprazole treatment on theophylline pharmacokinetics was studied in eight, non-smoking healthy male volunteers during repeated administration of a slow release formulation of theophylline. In a randomized double-blind cross-over study, the subjects received theophylline 5 mg·kg−1 per day with omeprazole 20 mg per day or identical placebo during two periods, each of 7 days, separated by a washout period of 7 days. The oral clearance of theophylline remained unchanged whether it was administered alone or with omeprazole (54.2 ml·min−1). The average urinary excretion of theophylline and its metabolites, 1,3 dimethyluric acid (1,3-DMU), 3-methylxanthine (3-MX), 1-methyluric acid (1-MU) amounted to 9%, 32%, 12% and 22% of the administered dose, respectively, and no significant change occured during concomitant treatment with omeprazole. Thus, the formation and clearance of the metabolites was not altered by omeprazole. Consequently, omeprazole in the recommended dose of 20 mg daily can safely be administered to patients on theophylline therapy.
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  • 51
    ISSN: 1432-1041
    Keywords: Metipranolol ; Liver cirrhosis ; pharmacokinetics ; pharmacodynamics ; beta-adrenoreceptor blockade
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The disposition kinetics and heart rate reducing effect of deacetylmetipranolol (DMP), the active form of the β-adrenoreceptor blocking agent metipranolol (MP), administered as a single 40 mg oral dose have been compared in 6 patients with cirrhosis and 6 healthy volunteers. The mean maximal DMP concentration was significantly higher and the time to reach the peak level shorter in the patients compared to the healthy subjects. There was also a significantly higher AUC of DMP, a shorter half-life of the rapid phase of the decline in DMP concentrations, a smaller central compartment and lower apparent DMP clearance in patients. A correlation with the albumin level was observed in cirrhotics for individual values of apparent DMP clearance (r=0.92) and AUC (r=-0.89). The maximal reduction in heart rate was recorded in patients at plasma DMP levels which were already significantly lower than the peak levels. Median inhibitory concentrations (IC50) and maximum possible heart rate reductions (Δ HRmax), obtained by fitting individual plots of the plasma DMP concentration-effect relationship to the inhibitory Emax model in the postdistributional phase of DMP disposition were significantly higher in cirrhotics than in healthy subjects. It is conjectured that down-regulation of adrenoreceptors due to chronic sympathetic activation in hepatic cirrhosis contributes to decreased sensitivity to the reduction in heart rate following a single dose of the beta-blocker.
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  • 52
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    European journal of clinical pharmacology 42 (1992), S. 371-374 
    ISSN: 1432-1041
    Keywords: Ambenonium chloride ; Myasthenia gravis ; dietary effect ; serum concentration ; adverse effects ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Influence of food on the serum concentration and kinetics ambenonium chloride (AMBC) has been examined in thirteen patients with myasthenia gravis (MG). Mean serum concentrations and Cmax during fasting were higher than those in the non-fasting state. The AUC (0–3 h) was also about four-times larger. The drug effects versus the serum concentration were observed to be anti-clockwise or clockwise. The effective range of the Cmax varied between patients. The unexpected increase in Cmax led to adverse muscarinic actions of AMBC, when the condition was changed from the non-fasting to the fasting state. It is recommended that the dose be changed during non-fasting treatment when adjusting the optimum regimen for patients myasthenia gravis. Patients must be advised to keep to the dosing and dietary schedule in order to avoid unexpected adverse actions to AMBC.
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  • 53
    ISSN: 1432-1041
    Keywords: Nitrendipine ; enantiomers ; stereoselectivity ; Renal failure ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of the enantiomers of nitrendipine has been studied in seven elderly patients with chronic renal failure (CRF) and in six control subjects (mean creatinine clearance 30 and 97 ml·min−1 respectively). Racemic nitrendipine 20 mg was given once daily for seven days and the pharmacokinetics of the enantiomers over the last dosage interval were determined using a stereospecific assay. In both groups nitrendipine exhibited stereoselective pharmacokinetics (AUC, Cmax), but the half-lives of the enantiomers did not differ in individual subjects. As an index of stereoselectivity, the mean S/R ratio of AUCs in control subjects (2.07) was not significantly different from the ratio in patients with CRF (2.68). The mean AUCs of (S)- and (R)-nitrendipine during the last dosage interval were increased in CRF by 132% and 85%, respectively. The observed doubling of the half-lives and the increases in Cmax did not reach significance because of the large variability in each group. Thus, the pharmacokinetics of oral nitrendipine is altered in CRF, but there was no change in the stereoselectivity of its pharmacokinetics.
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  • 54
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    European journal of clinical pharmacology 42 (1992), S. 429-433 
    ISSN: 1432-1041
    Keywords: Chloroquine ; Rheumatoid arthritis ; desethylchloroquine ; bisdesethylchloroquine ; blood levels ; toxicity ; therapeutic activity ; dose-effect relationship ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Blood levels of racemic chloroquine and its main metabolites desethylchloroquine and bisdesethylchloroquine were measured in 29 patients treated chronically for rheumatoid arthritis. In six patients, the concentrations were followed during a one day dosage interval. There was considerable intersubject variability in the steady state blood concentrations of chloroquine (range 36.6 to 3895 ng·ml−1) and its two main biotransformation products; the latter represented, respectively, 47.7% and 12.9% of the concentration of chloroquine. This finding shows the need for further studies in view of the known toxic effects of chloroquine and the inevitable accumulation due to the exceptionally long residence time of the compound and its metabolites. The main requirement, which has not yet been met, for adding chloroquine to the list of drugs for which therapeutic drug monitoring is useful, is the lack of information about its mechanism of action, and consequently the dose-effect relationships of its therapeutic and toxic actions. Regular ophthalmic examination, in particular, is strongly recommended. The relatively high concentrations of desethylchloroquine and bisdesethylchloroquine found during chronic treatment show the need for more information about the therapeutic value and adverse effects of the metabolites.
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  • 55
    ISSN: 1432-1041
    Keywords: Calcium channel blocker ; Nilvadipine ; blood pressure ; liver disease ; pharmacokinetics ; pharmacodynamics ; cirrhosis ; hepatitis
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Fourteen normotensive patients with liver disease (6 with cirrhosis and 8 with chronic hepatitis) and 7 healthy volunteers were given a single oral dose of nilvadipine 2 mg. In addition, nilvadipine 4 mg was administered orally twice daily for several months to 6 hypertensive patients with mild liver dysfunction and 18 hypertensives with normal liver function. A significant increase in plasma nilvadipine was found in the patients with cirrhosis as compared both to the normal and chronic hepatitis subjects; the time to peak concentration was similar among the three groups. The peak plasma nilvadipine concentration was closely correlated both with the serum albumin level and the retention of indocyanine green. Changes in blood pressure, pulse rate and various vasoactive hormones following a single oral dose of nilvadipine did not differ between the groups. Thus, an increase in plasma nilvadipine relative to the level in normal subjects was demonstrated in patients with cirrhosis following a single oral dose, as well as in patients with slight liver dysfunction following long-term oral administration.
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  • 56
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    European journal of clinical pharmacology 42 (1992), S. 481-485 
    ISSN: 1432-1041
    Keywords: Digoxin ; Spironolactone ; drug interaction ; biliary clearance ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The possibility of an inhibitory effect of spironolactone on the biliary clearance of digoxin has been investigated in 6 healthy subjects. Plasma clearance and the renal and biliary clearance of digoxin were determined twice at steady state (digoxin 0.5 to 1 mg·d−1 p.o. for 6 days), alone or in combination with spironolactone 200 mg daily, after an intravenous dose of digoxin (0.7 × oral dose) on Day 7. Plasma and urine were collected for 48 h. Biliary clearance of digoxin was determined on Day 8 by a duodenal perfusion technique. During spironolactone treatment plasma digoxin clearance tended to be lower (255 vs 224 ml/min; P=0.057) and renal clearance significantly lower (166 vs 144 ml/min), while the biliary clearance of digoxin remained unchanged (106 vs 103 ml/min). Thus, spironolactone reduced the renal clearance of digoxin by an average of 13%, without affecting its biliary clearance.
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  • 57
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    European journal of clinical pharmacology 42 (1992), S. 545-547 
    ISSN: 1432-1041
    Keywords: Vinorelbine ; anti-neoplastic agents ; vinca alkaloids ; pharmacokinetics ; lung neoplasms ; HPLC ; assay method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of vinorelbine has been investigated by a new HPLC method in 8 cancer patients receiving 8 weekly doses (30 mg·m−2) administered by brief infusion (15 min). The plasma concentration-time curves showed a tri-exponential decay with a long terminal half-life (44.7 h) and a high volume of distribution (Vz=75.61·kg−1). The concentrations after the 8th infusion were significantly lower than after the 1st infusion, but without significant modification of CL (1.28 l·h−1·kg−1) or AUC (0.80 mg·l−1·h). The pharmacokinetic parameters exhibited wide inter-individual variations. The results are consistent with those of previous RIA studies, although the HPLC method appears to be more specific and more precise.
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  • 58
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    European journal of clinical pharmacology 42 (1992), S. 663-666 
    ISSN: 1432-1041
    Keywords: Morphine ; Codeine ; drug metabolism ; pharmacokinetics ; systemic availability ; individual variability ; post-operative state
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The metabolism and systemic availability of codeine have been studied in 12 patients after cholecystectomy. They were given 20 mg codeine as an IV bolus dose on the first day after surgery and 50 mg codeine as a single oral on the fourth day after surgery. Codeine had a medium to high extraction ratio and a total plasma clearance of 10.8 (4.3) ml·min−1·kg−1. The clearance varied fourfold between subjects. All the patients were extensive metabolizers with regard to the debrisoquine/sparteine polymorphism, as tested using dextromethorphan as the probe drug. Nevertheless, the formation of morphine from codeine was very small and plasma morphine concentrations were below the detection limit of 3.3 nmol·1−1 (1 ng·ml−1). As a corollary, the morphine/codeine ratio in the the concentration-time curves was less than 3% in all the patients. The systemic availability of codeine varied extensively between subjects (range 12–84%). This might partly explain differences in the dose of codeine required as an analgesic.
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  • 59
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    European journal of clinical pharmacology 42 (1992), S. 671-673 
    ISSN: 1432-1041
    Keywords: Nifurtimox ; Changas' disease ; renal failure ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of nifurtimox, a drug used in the treatment of Trypanosoma cruzi infections, has been studied in seven patients with chronic renal failure undergoing haemodialysis, and in seven healthy subjects. Each subject took nifurtimox 15 mg·kg−1 orally and blood samples were obtained for 10 h after administration. Nifurtimox in serum was analyzed by HPLC. The patients with chronic renal failure had a higher Cmax than the control subjects due to a change in systemic availability. An alternative explanation would be that both the distribution volume and the clearance had changed. The mean half-life in the patients with chronic renal failure was similar to that in the healthy subjects.
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  • 60
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    European journal of clinical pharmacology 43 (1992), S. 209-210 
    ISSN: 1432-1041
    Keywords: Moxonidine ; Hydrochlorothiazide ; pharmacokinetics ; drug interaction ; steady-state ; healthy volunteers ; adverse effects
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  • 61
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    European journal of clinical pharmacology 43 (1992), S. 269-271 
    ISSN: 1432-1041
    Keywords: Lignocaine ; diabetes mellitus ; pharmacokinetics ; epidural anaesthesia
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of lignocaine has been compared after epidural anaesthesia in diabetics and nondiabetic patients. Epidural lignocaine 8 mg · kg−1 was given to 8 well controlled Type II diabetic and 8 nondiabetic patients and the plasma drug concentration in serial blood samples were measured by HPLC. The plasma level of lignocaine was lower in diabetics compared to non-diabetics. The peak level was attained at 20 min in both groups. The clearance of the drug was significantly higher, (39,9 vs 16,7 ml · min− · kg−) associated with a decreased elimination half-life and mean residence time. The study suggests that the rate of absorption of lignocaine is not altered after epidural administration and that its hepatic metabolism is increased in diabetics compared to non-diabetics.
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  • 62
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    European journal of clinical pharmacology 43 (1992), S. 289-294 
    ISSN: 1432-1041
    Keywords: Microdialysis ; Drug concentration ; parameter estimation ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Microdialysis has recently been adapted for sampling the extracellular fluid of various organs in order to measure drug concentrations, and the first clinical application has been published. My aim here is to provide simple rules about how to analyse pharmacokinetic data from such studies. The plotting of data on a time scale and the estimation of C (0) and slopes is not a trivial problem when multicompartmental models are assumed or sampling intervals are unequal. I have developed formulae and algorithms to solve the problem. A simple rule of thumb is given, suggesting when these formulae need to be applied. It is shown that the calculations of half-life and slopes is similar to standard methods for equal sample intervals and that calculation of AUC and clearance may be even more accurate for microdialysis data than for ordinary blood sampling, because of the time-integral character of the dialysis method. I have dealt with both zero-order and first-order kinetics.
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  • 63
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    European journal of clinical pharmacology 43 (1992), S. 437-439 
    ISSN: 1432-1041
    Keywords: Pirmenol ; pharmacokinetics ; elderly subjects ; age effect ; adverse effect
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The steady state pharmacokinetics of pirmenol was compared in twelve healthy young (aged 18 to 45 y) and 11 elderly subjects (over 65 y) subjects given pirmenol HCl 100 mg every 12 h for a total of 14 doses. In addition, the single-dose pharmacokinetics of pirmenol was determined following a 100 mg oral dose in the young subject group for comparison with the results of repeated administration. In the young subjects, the mean single-dose and steady-state CLR of pirmenol were similar; however, Ae was 29 % higher and CL/f was 22 % lower at steady state than after the single dose. Steady-state (fourteenth dose) Cmin, Cmax, tmax, λz, Ae, CL/f, CLR and V values were similar in the young and elderly subjects. Based on pharmacokinetic considerations, the dosage of pirmenol is unlikely to differ in young and elderly subjects.
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  • 64
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    European journal of clinical pharmacology 43 (1992), S. 441-443 
    ISSN: 1432-1041
    Keywords: Flecainide ; quinidine ; pharmacokinetics ; metabolism inhibition ; drug interaction ; renal transport
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have studied the effects of quinidine on ECG intervals and on the pharmacokinetics of flecainide and its two metabolites in 6 healthy men in an open randomized crossover study. Flecainide acetate (150 mg) was given as a constant rate i. v. infusion over 30 min. Quinidine (50 mg orally), given the previous evening, did not change the volume of distribution of flecainide (7.9 vs 7.41·kg−1), but significantly increased its half-life (8.8 vs 10.7 h). This was attributable to a reduction in total clearance (10.6 vs 8.1 ml·min−1·kg−1), most of it being accounted for by a reduction in non-renal clearance (7.2 vs 5.2 ml·min−1·kg−1). The excretion of the metabolites of flecainide over 48 h was significantly reduced. These findings suggest that quinidine inhibits the first step of flecainide metabolism, although it may also reduce its renal clearance, but to a lesser extent (3.5 vs 2.9 ml·min−1·kg−1). The effects of flecainide on ECG intervals were not altered by quinidine. Thus, quinidine tends to shift extensive metabolizer status for flecainide towards poor metabolizer status and may also alter its renal excretion.
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  • 65
    ISSN: 1573-1561
    Keywords: Cover crops ; wheat ; Triticum aestivum ; soybean ; Glycine max ; soil extracts ; germination bioassays ; phenolic acids ; hydroxamic acids ; allelopathy ; slope analysis ; ivy-leaved morning glory ; Ipomoea hederacea ; crimson clover ; Trifolium incarnalum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The primary objective of this research was to determine if soil extracts could be used directly in bioassays for the detection of allelopathic activity. Here we describe: (1) a way to estimate levels of allelopathic compounds in soil; (2) how pH, solute potential, and/or ion content of extracts may modify the action of allelopathic compounds on germination and radicle and hypocotyl length of crimson clover (Trifolium incarnatum L.) and ivyleaved morning glory (Ipomoea hederacea L. Jacquin.); and (3) how biological activity of soil extracts may be determined. A water-autoclave extraction procedure was chosen over the immediate-water and 5-hr EDTA extraction procedures, because the autoclave procedure was effective in extracting solution and reversibly bound ferulic acid as well as phenolic acids from wheat debris. The resulting soil extracts were used directly in germination bioassays. A mixture of phenolic acids similar to that obtained from wheat-no-till soils did not affect germination of clover or morning glory and radicle and hypocotyl length of morning glory. The mixture did, however, reduce radicle and hypocotyl length of clover. Individual phenolic acids also did not inhibit germination, but did reduce radicle and hypocotyl length of both species. 6-MBOA (6-methoxy-2,3-benzoxazolinone), a conversion product of 2-o-glucosyl-7-methoxy-1,4-benzoxazin-3-one, a hydroxamic acid in living wheat plants, inhibited germination and radicle and hypocotyl length of clover and morning glory. 6-MBOA, however, was not detected in wheat debris, stubble, or soil extracts. Total phenolic acids (FC) in extracts were determined with Folin and Ciocalteu's phenol reagent. Levels of FC in wheat-conventionaltill soil extracts were not related to germination or radicle and hypocotyl length of either species. Levels of FC in wheat-no-till soil extracts were also not related to germination of clover or morning glory, but were inversely related to radicle and hypocotyl length of clover and morning glory. FC values, solute potential, and acidity of wheat-no-till soil extracts appeared to be independent (additive) in action on clover radicle and hypocotyl length. Radicle and hypocotyl length of clover was inversely related to increasing FC and solute potential and directly related to decreasing acidity. Biological activity of extracts was determined best from slopes of radicle and hypocotyl length obtained from bioassays of extract dilutions. Thus, data derived from the water-autoclave extraction procedure, FC analysis, and slope analysis for extract activity in conjunction with data on extract pH and solute potential can be used to estimate allelopathic activity of wheat-no-till soils
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  • 66
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    Plant molecular biology 18 (1992), S. 423-427 
    ISSN: 1573-5028
    Keywords: Hordeum vulgare L. ; CM protein ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The primary structure of the insect α-amylase inhibitor CMa of barley seeds was deduced from a full-length cDNA clone pc43F6. Analysis of RNA from barley endosperm shows high levels 15 and 20 days after flowering. The cDNA predicts an amino acid sequence of 119 residues preceded by a signal peptide of 25 amino acids. Ala and Leu account for 55% of the signal peptide. CMa is 60–85% identical with α-amylase inhibitors of wheat, but shows less than 50% identity to trypsin inhibitors of barley and wheat. The 10 Cys residues are located in identical positions compared to the cereal inhibitor family with a Pro-X-Cys motif present in all.
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    Plant molecular biology 20 (1992), S. 849-856 
    ISSN: 1573-5028
    Keywords: GA regulation ; thiol-protease promoter ; wheat ; aleurone ; particle gun
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A wheat gene (A121) encoding a protein with sequence similarity to mammalian cathepsin B is regulated by gibberellic acid (GA) in aleurone layers of germinating grains. To analyse the mechanism of A121 regulation, its promoter was fused to the β-glucuronidase reporter gene (GUS) and introduced by micro-projectile bombardment into aleurone layers of oat. With 2.3 kb of promoter sequence, the GUS expression was enhanced by GA treatment. This effect was reversed by abscisic acid (ABA). This result showed for A121, like the α-amylase genes, that the regulation by GA and ABA was at the level of transcription. The GA responsiveness of the promoter was retained with as little as 276 bp of promoter sequence. Sequence comparison with a GA responsive promoter of an α-amylase gene identified the conserved element GCAACGGCAACGATGG which is required intact for full expression of both promoters. However, there was no identifiable similarity in the cathepsin-like promoter with the GA-responsive element of α-amylase promoters with the consensus sequence TAACAAA, suggesting that GA affects more than one mechanism of transcriptional control.
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  • 68
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    Plant molecular biology 20 (1992), S. 991-995 
    ISSN: 1573-5028
    Keywords: retrotransposon-like element ; sequence analysis ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract WIS-2-1A, a 8624 bp insertion in the Glu-1A-2 locus of chromosome 1A of wheat, consists of two 1755 bp long terminal repeats enclosing a 5114 bp internal region. No long open reading frames could be found, but inspection of the predicted amino acid sequence showed regions with homology to retrotransposon structures, including a methionine tRNA initiator binding site, a nucleotide binding domain, a protease, an integrase and a polymerase. DNA replication errors have resulted in frame-shifts in the protein coding region, suggesting that retrotransposition of WIS-2-1A, if it occurs, must be mediated by trans-acting factors.
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  • 69
    ISSN: 1573-5028
    Keywords: TATA box ; TFIID ; transcription factor ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We isolated a complementary DNA (cDNA) encoding the TATA-binding factor ‘TFIID’ from a wheat seedling cDNA library. The wheat TFIID transcript of 1.2 kb poly(A)+ RNA was expressed at a low level early in germination, but gradually increased as the seedlings developed. In vitro binding experiments showed that the bacterially expressed wheat TFIID protein could specifically bind to the TATA boxes of the cauliflower mosaic virus (CaMV) 35S, wheat histone H3 and adenovirus major late genes with different affinity. A comparison with Arabidopsis TFIID showed the presence of a plant-specific region consisting of 13 amino acids at the divergent amino terminus and a conserved region (182 amino acids) at the carboxy terminus longer than that observed in yeasts (180 amino acids) and animals (181 amino acids).
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  • 70
    ISSN: 1573-5028
    Keywords: rRNA ; PCR ; ITS ; DNA sequence ; nucleotide ; Triticum speltoides ; wheat
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  • 71
    ISSN: 1573-5028
    Keywords: rRNA ; PCR ; ITS ; DNA sequence ; nucleotide ; Triticum aestivum ; wheat
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  • 72
    ISSN: 1573-5028
    Keywords: mitochondrial DNA ; repeated sequences ; ribosomal RNA ; t-elements ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report the sequence of a 7.2 kilobase pair DNA fragment containing a copy of the wheat mitochondrial gene (rrn26) that encodes the mitochondrial large-subunit ribosomal RNA (26S rRNA). The mature 26S rRNA was determined by direct RNA sequencing to be 3467 nucleotides long, and to share a 5′-terminal pentanucleotide (5′-AUCAU), thought to be important in post-transcriptional processing, with the wheat mitochondrial small-subunit (18S) rRNA. Two other prominent features of the sequence were noted. First, upstream of rrn26 are located two tandem copies of a 70 base pair element containing a putative mitochondrial promoter motif (TCGTATAAAAA). Second, downstream of rrn26 is a sequence element that, if transcribed, would produce and RNA with a secondary structure resembling that of tRNAs but differing sufficiently from the latter structure to preclude any transcript from functioning normally in translation. These upstream and downstream sequence elements may play a role in the expression of rrn26 in wheat mitochondria.
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  • 73
    ISSN: 1573-5028
    Keywords: chloroplast ; gene expression ; photosystem 2 ; transcription ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The time course of the accumulation of the transcripts from 13 psb genes encoding a major part of the proteins composing photosystem II during light-induced greening of dark-grown wheat seedlings was examined focusing on early stages of plastid development (0.5 h through 72 h). The 13 genes can be divided into three groups. (1) The psbA gene is transcribed as a single transcript of 1.3 kb in the dark-grown seedlings, but its level increases 5- to 7-fold in response to light due to selective increase in RNA stability as well as in transcription activity. (2) The psbE-F-L-J operon, psbM and psbN genes are transcribed as a single transcript of 1.1 kb, two transcripts of 0.5 and 0.7 kb and a single transcript of 0.3 kb, respectively, in the dark-grown seedlings. The levels of accumulation of every transcript remain unchanged or rather decrease during plastid development under illumination. (3) The psbK-I-D-C gene cluster and psbB-H operon exhibit fairly complicated northern hybridization patterns during the greening process. When a psbC or psbD gene probe was used for northern hybridization, five transcripts differing in length were detected in the etioplasts from 5-day old dark-grown seedlings. After 2 h illumination, two new transcripts of different length appeared. Light induction of new transcripts was also observed in the psbB-H operon.
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  • 74
    ISSN: 1573-0646
    Keywords: pharmacokinetics ; cytotoxicity ; molecular combination ; fluorouracil ; nitrosourea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary B.3839 is the prototype compound in a series of novel molecular combinations of chloroethylnitrosoureas and 5-fluorouracil(5-FU) and has been tested against MAC tumours in mice. Previous studies have shown it is moderately active against MAC15A and highly active against MAC13 though this activity is dependent on route of administration. The aim of this study was to determine whether bioavailability could explain this difference in anti-tumour activity. Plasma levels of B.3839 and 5-FU after i.p. and oral administration were measured using HPLC. Non tumour-bearing and MAC26 bearing mice gave almost identical plasma profiles after i.p. administration with the Cmax being 29.8 and 30.4μ gml−1 and t1/2 16 and 15 min. The AUCs were 15.3 and 13.9μg h ml−1 suggesting tumour load had no influence over plasma levels. Oral administration gave a much lower Cmax of 8.0μg ml−1 but an AUC of 15.2μg h ml−1 due to a longer terminal t1/2 (94 min) giving 99% bioavailability. Levels of 5-FU release from B.3839 by either route were considered too small to influence anti-tumour activity. Cytotoxicity assaysin vitro against the MAC lines gave IC70 values of 5.3, 13.8 and 8.6μg ml−1 for MAC 26,13 and 15A respectively after a one hour exposure. Bone marrow toxicity was shown to be less severe than that of TCNU which is currently in clinical trials. The results show bioavailability alone is not enough to explain tumour response. There appears to be a need for a threshold concentration (C) to be maintained for a period of time (t).
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  • 75
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    Journal of pharmacokinetics and pharmacodynamics 20 (1992), S. 95-99 
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; physiological model ; cisplatin ; DDP ; cis-dichlorodiammineplatinum(II)
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    Topics: Chemistry and Pharmacology
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  • 76
    ISSN: 1573-8744
    Keywords: prednisolone ; pharmacokinetics ; pharmacodynamics ; corticosteroids ; protein binding
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and pharmacodynamics of prednisolone were evaluated in normal male volunteers. Seven subjects completed 3 phases: 16.4−and 49.2−mg iv prednisolone, and a phase with no drug to assess baseline responses. Plasma concentrations of prednisolone and urine concentrations of prednisolone and 5 metabolites were assayed by HPLC. Protein binding of prednisolone was measured by ultrafiltration. The polyexponential disposition of free and total plasma prednisolone were evaluated and apparent parameters were compared between doses. Suppression of plasma cortisol and alterations in blood basophil and helper-T cell trafficking were used as pharmacodynamic indices. Pharmacodynamic models were used to relate total or free plasma prednisolone concentrations to each of these effects generating response parameters and IC50 (50% inhibitory) concentrations common to both doses. The pharmacokinetics of total drug were comparable to previous findings with CLand Vss increasing with dose. Free prednisolone exhibited slight capacitylimited elimination and distribution as CLand Vss decreased with the larger dose. Pharmacodynamic models jointly fitting all three phases characterized the suppression/trafficking phenomena equally well with use of total or free drug concentrations. In each case the models provided realistic values of parameters relating to steroid sensitivity-in particular IC50-and to the underlying physiology of the affected systems. This study comprehensively elucidates the complexities of prednisolone pharmacokinetics and demonstrates how plasma concentration-time profiles of total or free prednisolone can be utilized for evaluation of prednisolone pharmacodynamics.
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  • 77
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    Journal of pharmacokinetics and pharmacodynamics 20 (1992), S. 147-169 
    ISSN: 1573-8744
    Keywords: computers ; pharmacokinetics ; pharmacodynamics ; infusions ; drug delivery ; computer driven ; effect site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Computer-controlled infusion pumps incorporating an internal model of drug pharmacokinetics can rapidly achieve and maintain constant drug concentrations in the plasma. Although these pumps offer more accurate titration of intravenous drugs than is possible with simple boluses or constant rate infusions, the choice of the plasma as the target site is arbitrary. The plasma is not the site of drug effect for most drugs. This manuscript describes two algorithms for calculation of the infusion rates necessary for a computer-controlled infusion pump to rapidly achieve, and then maintain, the desired target concentration at the site of drug effect rather than in the plasma.
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  • 78
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    Journal of pharmacokinetics and pharmacodynamics 20 (1992), S. 611-635 
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; pharmacodynamics ; plasma concentration-effect relation-ship ; anesthesia ; analgesic ; narcotic ; opioids ; alfentanil ; brain ; electroencephalograph ; spectral edge ; semilinear canonical correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To examine the relationship between the electroencephalograph (EEG) and plasma opioid concentration, one would like to collapse the high-dimensional EEG signal into a univariate quantity. Such a simplification of the EEG is desirable because a univariate quantity can be modeled using standard nonlinear regression techniques, and because most of the information in the EEG is redundant or unrelated to drug concentration. In previous studies of the EEG response to opioids, the manner in which a univariate component was extracted from the EEG was ad hoc.In this paper, this extraction was performed optimally using a new statistical technique, semilinear canonical correlation. Data from 15 patients who received an intravenous infusion of the semisynthetic opioid alfentanil were analyzed. The components of the EEG that were nearly maximally correlated with plasma drug concentration were found, based on a standard pharmacokinetic-pharmacodynamic model. Two new EEG components were produced from the powers in the frequency spectrum of the EEG: a weighted sum of the logarithms of the powers, and a weighted sum of the powers expressed as percentages of the total power. These components both had a median R2 of 0.84, compared to median R2sranging from 0.37 to 0.83 for five commonly used ad hocEEG components. The new components also had less variability in R2 between subjects.
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  • 79
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    Journal of pharmacokinetics and pharmacodynamics 20 (1992), S. 511-528 
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; population analysis ; model building ; generalized additive models ; NONMEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract One major task in clinical pharmacology is to determine the pharmacokinetic-pharmacodynamic (PK-PD) parameters of a drug in a patient population. NONMEM is a program commonly used to build population PK-PD models, that is, models that characterize the relationship between a patient's PK-PD parameters and other patient specific covariates such as the patient's (patho)physiological condition, concomitant drug therapy, etc. This paper extends a previously described approach to efficiently find the relationships between the PK-PD parameters and covariates. In a first step, individual estimates of the PK-PD parameters are obtained as empirical Bayes estimates, based on a prior NONMEM fit using no covariates. In a second step, the individual PK-PD parameter estimates are regressed on the covariates using a generalized additive model. In a third and final step, NONMEM is used to optimize and finalize the population model. Four real-data examples are used to demonstrate the effectiveness of the approach. The examples show that the generalized additive model for the individual parameter estimates is a good initial guess for the NONMEM population model. In all four examples, the approach successfully selects the most important covariates and their functional representation. The great advantage of this approach is speed. The time required to derive a population model is markedly reduced because the number of necessary NONMEM runs is reduced. Furthermore, the approach provides a nice graphical representation of the relationships between the PK-PD parameters and covariates.
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  • 80
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    Journal of pharmacokinetics and pharmacodynamics 20 (1992), S. 591-609 
    ISSN: 1573-8744
    Keywords: nicotine ; cotinine ; pharmacokinetics ; physiologically-based pharmacokinetic model ; interindividual variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Physiologically based pharmacokinetic (PBPK) models have been developed describing the disposition kinetics of nicotine and its major metabolite, cotinine, in man. Separate 9-compartment, flow-limited PBPK models were initially created for nicotine and cotinine. The physiological basis for compartment designation and parameter selection has been provided;chemical-specific tissue-to-blood partition coefficients and elimination rates were derived from published human and animal data. The individual models were tested through simulations of published studies of nicotine and cotinine infusions in man using similar dosing protocols to those reported. Each model adequately predicted the time course of nicotine or cotinine concentrations in the blood and urine following the administration of nicotine or cotinine. These individual models were then linked through the liver compartments to form a nicotine-cotinine model capable of predicting the metabolic production and disposition of cotinine from administered nicotine. The potential for integrating this functional PBPK model with an appropriate pharmacodynamic model for the characterization of nicotine's physiological effects is discussed.
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  • 81
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    Journal of pharmacokinetics and pharmacodynamics 20 (1992), S. 397-412 
    ISSN: 1573-8744
    Keywords: neural networks ; pharmacodynamics ; pharmacokinetics ; modeling ; drug effect prediction ; alfentanil ; model testing ; system analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Neural networks (NN) are computational systems implemented in software or hardware that attempt to simulate the neurological processing abilities of biological systems, in particular the brain. Computational NN are classified as parallel distributed processing systems that for many tasks are recognized to have superior processing capability to the classical sequential Von Neuman computer model. NN are recognized mainly in terms of their adaptive learning and selforganization features and their nonlinear processing capability and are considered most suitable to deal with complex multivariate systems that are poorly understood and difficult to model by classical inductive,logically structured modeling techniques. A NN is applied to demonstrate one of the potentially many applications of NN for modeling complex kinetic systems. The NN was used to predict the effect of alfentanil on the heart rate resulting from a complex infusion scheme applied to six rabbits. Drug input-drug effect data resulting from a repeated, triple infusion rate scheme lasting from 30 to 180 min was used to train the NN to recognize and emulate the input-effect behavior of the system. With the NN memory fixed from the 30- to 180-min learning phase the NN was then tested for its ability to predict the effect resulting from a multiple infusion rate scheme applied in the subsequent 180 to 300 min of the experiment. The NN's ability to emulate the system (30–180 min) was excellent and its predictive extrapolation capability (180–300 min) was very good (mean relative prediction accuracy of 78%). The NN was best in predicting the higher intensity effect and was able to identify and predict an overshoot phenomenon likely caused by a withdrawal effect from acute tolerance. Current modeling philosophy and practice is discussed on the basis of the alternative offered by NN in the modeling of complex kinetic systems. In modeling such systems it is questioned whether traditional modeling practice that insists on structure relevance and conceptually pleasing structures has any practical advantages over the empirical NN approach that largely ignores structure relevance but concentrates on the emulation of the behaviorof the kinetic system. The traditional searching for appropriate models of complex kinetic systems is a painstakingly slow process. In contrast, the search for empirical models using NN will continue to improve, limited only by technological advances supporting the very promising NN developments.
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  • 82
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    Plant foods for human nutrition 42 (1992), S. 165-173 
    ISSN: 1573-9104
    Keywords: Calcium ; absorption ; wheat ; Bengal gram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheatchapati, wheat+Bengal gram (80∶20 and 70∶30)chapatis and casein diets, at 10 percent protein level, were fed to rats for 12 weeks to study the effect on calcium utilization. The supplementation of Bengal gram to wheat diets significantly improved the calcium absorption. The urinary calcium excretion in wheat+Bengal gramchapati diets was significantly less than that of wheatchapati diet fed group. The in vivo45Ca absorption (CPM/100 μl serum) was also less in wheatchapati group as compared to wheat+Bengal gramchapati diets fed groups. The supplementation of legumes to cereals improved the calcium utilization and it may be concluded that there will be no risk of occurance of protein induced hypercalciuria.
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  • 83
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    Plant and soil 140 (1992), S. 311-314 
    ISSN: 1573-5036
    Keywords: boron toxicity ; diagnosis ; foliar analysis ; mineral nutrition ; nutrient leaching ; rain ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of rain on foliage elemental composition, especially B, was assessed using samples of wheat collected at three harvests from a field trial conducted in soil containing excessive levels of B. Moderate rainfall substantially decreased both the B concentration and content of whole shoots and young leaves. The change in B concentration due to rain suggests that foliar analysis is unreliable for diagnosing B toxicity. For the other elements examined (Ca, Cu, Mg, Mn, Mg, P, S, Zn), rainfall had little effect.
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  • 84
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    Plant and soil 142 (1992), S. 281-285 
    ISSN: 1573-5036
    Keywords: barley ; mixed-cropping ; peas ; root activity ; rooting-depth ; tracers ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Lithium was used as a non-radioactive tracer to investigate the root activity of two cereals (wheat and barley), and of two contrasting cultivars of pea (leafy and semi-leafless), both in pure stands and in mixtures. The mixtures included combinations of each cereal with each pea cultivar in single rows, alternative rows and cross-drilled. Total lithium uptake (mg m-2) was higher for wheat than for barley, and higher for semi-leafless pea than for leafy peas. Growing cereals with peas reduced the total lithium uptake by peas, compared with pure stands, especially in alternate-row mixtures. Growing peas with cereals only reduced the total Li uptake by cereals when they were cross-drilled. The Li uptake by wheat, barley and peas generally decreased with soil depth in a similar manner; however, semi-leafless peas absorbed proportionately more Li from close to the soil surface than did leafy peas. Both pea cultivars absorbed more Li at 10–20 cm depth when grown in intimate mixtures with cereals, compared with less intimate mixtures or pure stands. The potential of lithium as a non-radioactive tracer in mixed-cropping studies is briefly discussed.
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  • 85
    ISSN: 1573-5036
    Keywords: aluminium ; aluminium tolerance ; calcium ; magnesium ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The activities of inorganic, monomeric aluminium (Al) species in the root environment are important in the toxicity of Al to plant roots, which may be ameliorated by increased activities of basic cations. Additionally, it has been suggested that electro-chemical processes in walls of root cells play a role in Al tolerance. Empirical models were proposed to accomodate genetic and calcium (Ca) and magnesium (Mg) ameliorative effects on Al toxicity. The models were tested using data from a solution culture study (with ionic strength 1.6 to 8.6 mM) in which wheat (Triticum aestivum L.) cvv. Warigal (Al-sensitive) and Waalt (Al-tolerant) were grown for 28 d at 0, 10 and 20 μM Al, in factorial combination with 200, 400, 800 and 1600 μM Ca and 100, 200, 400 and 800 μM Mg. There was a poor relationship between relative total dry mass (TDM) (calculated as a percentage of the average TDM of each cultivar in the absence of added Al) and the activity of Al3+ or the sum of the activities of the monomeric Al species in solution. A model based on the ratios of activities of cations in solution, taking valency into consideration, was more successful, accounting for ca 85% of the observed variation in relative TDM. There were no systematic variations between observed values and those estimated by the model.
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  • 86
    ISSN: 1573-5036
    Keywords: ammonium ; cyanides ; Gaeumannomyces graminis var tritici ; nitrate ; nitrogen fertilizer ; pseudomonads ; soil conduciveness ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a field cropped with wheat, a high and low level of soil conduciveness to take-all were induced by applying a nitrogen fertilizer with either calcium nitrate or ammonium sulphate. From these two soils, two representative populations of fluorescent pseudomonads were tested for their in situ behaviour. Take-all index and root dry weight were assessed on plants cropped in soils infested with Gaeumannomyces graminis var tritici (Ggt) and each bacterized with one of the isolates of fluorescent pseudomonads. The bacteria tested can be split into three groups: antagonists which reduce take-all, deleterious isolates which aggravate the disease and neutral without evident effect on the disease. The predominance of antagonistic fluorescent pseudomonads in the NH4-treated soil and the predominance of deleterious ones in the NO3-treated soil was confirmed after statistical analysis. The microbial impact on take-all must be more considered as the resulting effect of divergent activities of both rhizobacteria types than the only consequences of the presence of antagonistic pseudomonads. All the high cyanogenic pseudomonads were antagonists in situ and were more numerous in the NH4-treated soil than in the NO3-treated soil.
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  • 87
    ISSN: 1573-5036
    Keywords: ammonium ; Gaeumannomyces graminis var tritici ; nitrate ; nitrogen fertilizers ; fluorescent pseudomonads ; root system ; soil conduciveness ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Take-all of wheat, caused by Gaeumannomyces graminis var tritici (Ggt), is reduced by ammoniacal fertilizers as compared to nitrate sources. This influence of nitrogen on the disease is only observed on nodal roots at flowering. But soil conduciveness to take-all, as measured in a soil bioassay, is modified earlier. Forty days after nitrogen application at early tillering, the NH4-treated soil became less conducive than the NO3-treated one. When nitrogen applications are done at sowing and at tillering, differences in disease propagation between the two soils are enhanced. Results from four years of experimentation show that when the level of natural soil inoculum is high, disease severity is reduced by ammonium, showing an effect on the parasitic phase of Ggt. At a low level of natural inoculum the effect of the source of nitrogen is mainly observed on the percent of infected plants, indicating that the saprophytic and preparasitic phases are affected. Rhizospheric bacterial populations increase from sowing to tillering, but differences on take-all conduciveness after tillering are not correlated with differences in the amounts of aerobic bacteria or fluorescent pseudomonads isolated from soils treated with different sources of nitrogen. Qualitative changes in fluorescent Pseudomonas spp. populations, like in vitro antagonism, are more likely to explain differences in soil conduciveness to take-all than are quantitative changes in this group. Nevertheless, the introduction of Ggt in a cropped soil leads to a greater increase in fluorescent pseudomonads populations than in total aerobic bacteria. The delay between reducing soil conduciveness and reducing disease in the field with ammonium nitrogen fertilization, the qualitative change of fluorescent pseudomonads populations and the role of necroses in rhizobacteria multiplication, provide information leading to our representation of a dynamic model based on the differentiation of the wheat root system into seminal and nodal roots.
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  • 88
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    Plant and soil 146 (1992), S. 163-168 
    ISSN: 1573-5036
    Keywords: genetic variability ; NIR ; ploidy ; phosphorus ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract More efficient utilization of phosphorus by wheat plants is needed to extend the useful life of the phosphate reserves in the world, to reduce the cost of producing crops, and to improve the value of the grain and the straw produced. In this paper definitions of efficient use of phosphorus by wheat are reviewed, genotypic variation in phosphorus efficiency is reported, some consequences of breeding for greater efficiency are discussed, and ways to select more efficient genotypes are suggested.
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  • 89
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    Euphytica 60 (1992), S. 89-95 
    ISSN: 1573-5060
    Keywords: cuckoo effect ; gametocidal chromosome/gene ; preferential transmission ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A translocated chromosome segment, derived from Thinopyrum distichum, carries the leaf rust resistance allele Lr19d and a segregation distorter allele, Sd-1d. In translocation heterozygotes, male and female gametophytes lacking the translocation are aborted, the severity of the effect depending on the genotype of the hybrid. The selective abortion of the gametophytes with a normal chromosome 7D appears to be based on the absence of the translocated chromosome rather than the presence of the normal chromosome. The magnitude of the gametocidal response, elicited by Sd-1d, is under multigenic control. A number of chromosomes, the individual effects of which are generally small, may act to suppress or promote the response. Chromosome arms 2AL, 2BL, 5BL and 5DL of ‘Chinese Spring’ were found to reduce sensitivity to the presence of the gametocidal chromosome. Chromosome 3B of ‘Inia 66-1’ also reduce the gametocidal response while chromosome arm 6DS of ‘Chinese Spring’ may promote the effect
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  • 90
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; stress tolerance ; genetic variance ; genetic correlation ; selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat (Triticum aestivum L.) cultivars grown in the southern Great Plains of the U.S.A. are exposed to a wide range of moisture conditions due to large fluctuations in the amount and frequency of rainfall. Yield stability under those conditions is therefore a desirable trait for wheat breeders. Our primary objective was to quantify various genetic parameters for grain production in drought-stressed and irrigated environments. We also attempted to predict and measure yield responses when selection is practiced in either drought-stressed or irrigated environments, or both. Seventy F2-derived lines from the cross, TAM W-101/Sturdy, were evaluated at Goodwell, OK, under irrigated and naturally drought-stressed conditions in 1987 and 1988. Genetic variance and heritability estimates were higher in the irrigated environment than in the drought-stressed environment. The genetic correlation coefficient for yields in the two environments was 0.20±0.16, indicating that selection of widely adapted genotypes requires testing in both environments. Based on the genetic variance/covariance structure of this particular population, the linear index which maximized the combined expected gain in both environments was 0.66Y1 + 0.34Y2, in which Y1 and Y2 are yields in the irrigated and drought-stressed environments. This index is not expected to apply across all populations; rather, it further supports the hypothesis that testing in either environment alone (drought stressed or irrigated) may not be most effective for increasing either mean productivity or yield under drought stress.
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    Euphytica 62 (1992), S. 111-117 
    ISSN: 1573-5060
    Keywords: aluminium ; root growth ; screening ; tolerance ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Aluminium tolerance of 83 genotypes from Croatian and Yugoslav Triticum aestivum germplasm was evaluated in nutrient solutions having Al3+ activities of 0, 12.5 and 25 μM. Relative root length (25 μM Al3+/0 Al) of various genotypes ranged from 2 to 97% (from very sensitive to tolerant to Al). No genotype with Al tolerance close to that of very tolerant cultivar Atlas-66 was found. Soil, climatic, fertilization, and liming effects that wheat plants giving seeds for the nutrient solution Al-tolerance screening had been subjected to during their growth cycle did not influence the Al-tolerance ranking. Significant correlation was found between screening wheat for Al tolerance in nutrient solutions and in acid Pseudogley soil amended with five rates of limestone in a greenhouse experiment. Seed protein concentration was significantly related to the Al-tolerance ranking (r2 = 0.962). Such a significant correlation was not obtained in a case of rheological and other quality characteristics of seeds. Al-tolerant wheat genotypes identified in this study will be used in breeding for improved Al tolerance.
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  • 92
    ISSN: 1573-5060
    Keywords: heading time ; narrow-sense earliness ; photoperiodic response ; Triticum aestivum ; vernalization requirement ; winter hardiness ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary For breeding early heading wheat cultivars with resistance to frost damage which are well adapted to dry areas of West Asia and North Africa, the relationships between winter hardiness, ear primordia development and heading traits, i.e. veernalization requirement, photoperiodic response and narrow-sense earliness, were assessed using a total of 30 genotypes of wheat (Triticum aestivum L.) grown in an experiment in Syria. The results of artificial freezing tests indicated that cultivars with good winter hardiness were to be found only in the winter wheat cultivars which required 50 or more days of vernalization treatment. These winter wheat cultivars did not initiate internode elongation without vernalization even at 95 days after planting. Thus their ear primordia were still underground and were protected from frost injury at this stage. Photoperiodic response and narrow-sense earliness were not associated with winter hardiness and earliness of internode elongation, but were related to the number of days to heading after planting. This indicated the possibility for breeding early heading cultivars with winter hardiness and tiller frost avoidance by combining high vernalization requirement, short narrow-sense earliness and neutral response to photoperiod.
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  • 93
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    Euphytica 63 (1992), S. 3-22 
    ISSN: 1573-5060
    Keywords: wheat ; Triticum aestivum ; yellow (stripe) rust ; Puccinia striiformis ; septoria ; Septoria tritici ; S. nodorum ; eyespot ; Pseudocercosporella herpotrichoides ; resistance genetics ; pathogen variation ; durable resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This introductory chapter contains some general comments about plant breeding and breeding for disease resistance. The use of disease resistant crop plants is an environmentally favourable method of controlling disease but the process of breeding for disease resistance is subject to several constraints. Among them is the variability of pathogens in relation to host resistance. Some parts of this variation can be resolved into gene-for-gene interactions, but the boundaries within which such interactions can be detected are not sharp. The discussion of this variation is illustrated by reference to some important diseases of wheat, especially yellow rust, septoria and eyespot. The objective of obtaining durable resistance is discussed and some contributions of new genetical and molecular techniques to breeding for resistance are considered. It is suggested that new technology will enhance breeding for disease resistance but that established techniques of plant breeding will remain relevant and important.
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  • 94
    ISSN: 1573-5036
    Keywords: Alternaria alternata ; black point ; fertilization ; irrigation ; nitrogen ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agronomic studies were conducted to examine the effect of fertilizer N on black point incidence in Fielder soft white spring wheat (Triticum aestivum L. em Thell.). Black point incidence rose with increases in the amount of N supplied either as fertilizer applied during the growing season in irrigation water or as soil N, specifically nitrate, from fertilizer N application in previous years. A comparison of four different irrigation regimes demonstrated that black point incidence was highest under frequent irrigation (irrigate to field capacity at 75% available moisture) and lowest under conventional irrigation (irrigate to field capacity at 50% available soil moisture). In each irrigation regime, disease incidence increased as N rates were raised from 0 to 120 kg ha-1. A residual fertilizer-N study demonstrated in 1985 and 1986 that black point incidence generally rose with increasing levels of nitrogen from either preplant applications in the spring or soil nitrate from the previous year. However, additions of fertilizer N were shown to slightly reduce black point incidence at soil nitrate levels above 150 kg ha-1. A two-year fertilizer N study demonstrated that in treatments receiving the same amount (90 kg ha-1) of fertilizer N, the amount broadcast as a preplant treatment versus the amount applied in irrigation water in a fertigation treatment had no effect on black point incidence, but all fertilized treatments had significantly higher levels of disease than the unfertilized check.
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  • 95
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    Plant and soil 146 (1992), S. 55-59 
    ISSN: 1573-5036
    Keywords: acid soils ; low pH ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Shoot length (cm), shoot fresh weight (g/pot), root length (cm), and root fresh weight (g/pot) were measured on six cultivars of wheat (Triticum aestivum L. cv Saluda, C9733, Gore, Stacy, FL301, and FL302) grown at pH 6.0, 5.5, 5.0, 4.5, or 4.0 for 14 days in ‘white quartz flintshot’ sand. Plants were watered on alternate days with pH-adjusted buffer solutions. All measured plant parameters decreased as H+ concentration increased from pH 6.0 to 4.0. Decreased lengths of shoots and roots were similar among the cultivars as the pH decreased. This indicated a uniform response of wheat cultivars to excess H+ concentration in the soil solution; however, the decrease in shoot and root length was only about 50% as large as was previously reported for sorghum [Sorghum bicolor (L.) Moench.].
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  • 96
    ISSN: 1573-5036
    Keywords: aluminium ; genetics ; inheritance ; toxicity ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of Al on the growth of plants derived from the F3 generation of a cross between Al tolerant (Waalt) and Al sensitive (Warigal) wheat cultivars, grown in low ionic strength nutrient solutions, were assessed by a number of methods viz; root length and haematoxylin stain after 3 days exposure to Al and plant top and root yields, and root length and visual assessment for Al damage after 4 weeks growth. Of these methods haematoxylin stain (3 days) and visual assessment at 4 weeks identified the same plants as being sensitive or tolerant to Al and clearly segregated the 2 populations. Consequently these 2 methods were used as ‘standard’ techniques to determine the ability of the other methods to distinguish between tolerant and sensitive plants. The ratio of plant top: root yields clearly segregated the 2 populations. The 2 populations could not be clearly distinguished based on plant top or root yields, or on root length either after 3 days or 4 weeks exposure to Al. Within the population of tolerant plants, root length was significantly correlated with root weight (r2=0.86) and top weight (r2=0.71). None of these relationships were significant for the population of sensitive plants. These techniques were applied in a number of separate experiments on the F2 and F3 populations from a Waalt × Warigal cross. The results indicate that Al tolerance in wheat is inherited by a single gene and that this gene has incomplete dominance.
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  • 97
    ISSN: 1573-5036
    Keywords: aluminium ; electron microscope ; light microscope ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root tips from aluminium (Al) tolerant (Waalt) and Al sensitive (Warigal) wheat (Triticum aestivum (L). Thell.) cultivars exposed to low concentrations of Al (10 μM) for 10, 24 and 72 hours were examined under the light and electron microscope. After fixing and embedding, longitudinal and transverse thin and ultrathin sections were cut. There was no evidence of Al damage to the root tips of the Al tolerant cultivar under both the light and electron microscope. For the Al sensitive cultivar, Al had no observable effect on the root tips 10 hours after Al addition when examined under the light microscope. When examined under an electron microscope, electron dense globular deposits were observed between the cell wall and cell membrane of the epidermal cells. There was not obvious damage to the cell cytoplasm. Two or 3 days after Al addition, light microscopy showed that the cells in the root tips had become swollen and extensively vacuolated. The tissues appeared disorganised and degenerate, particularly in the epidermis and outer cortical cells. The electron microscope also revealed a thickening of the cell wall. The cell wall was broken down, particularly in the epidermis in the region 4–6 mm from the root tip. The tissue in the meristematic area was largely intact.
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  • 98
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    Plant and soil 146 (1992), S. 89-98 
    ISSN: 1573-5036
    Keywords: barley ; drought ; halophytes ; productivity ; salinity ; salt tolerance ; sunflower ; water-use efficiency ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The productivity of wheat and barley was compared in soils of different salt concentrations with a limited water supply. Productivity was assessed as total dry weight or dry weight per unit of water used (water use efficiency, WUE). Barley achieved the highest productivity because it used more of the available water and it had a greater WUE for above-ground dry weight. However, when WUE for total organic weight of roots and shoots was determined, or WUE was corrected for grain production, wheat and barley had the same productivity. In two experiments in drying soils with different salt concentrations but the same amount of soil water, wheat and barley had a higher dry weight than salt-tolerant grasses and they were more productive than C4 halophytes and non-halophytes when adjusted for water use. In one experiment, sown at a low plant density, barley and wheat used less water than some halophytes and they completed their life cycle leaving some water behind in the soil. Their higher WUE did not compensate for their lower water use. However, when all species were sown at a high density, wheat and barley were either as productive or more productive than the most salt-tolerant species, including a C4 halophyte, as they used all the available water and had the highest WUE. A sunflower cultivar was similary more productive than a salt-tolerant relative. The contribution that salt-tolerant relatives of wheat, barley and sunflower can make to genetically improving the productivity of these species in dry saline soils is questioned.
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  • 99
    ISSN: 1573-5036
    Keywords: boron ; genetic variation ; major genes ; uptake ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Physiological and genetic studies have been undertaken to further the understanding of genetic variation in response to high concentrations of B in the soil and so facilitate the breeding of tolerant varieties for cultivation in high B regions. Genetic variation in response to high concentrations of B has been identified for a number of crop and pasture species of southern Australia, including wheat, barley, oats, field peas and annual pasture medics. The wheat variety Halberd, which was the most widely grown variety in Australia during the 1970s and early 1980s, is the most tolerant of the current Australian wheat varieties. The mechanism of tolerance for all species studied is reduced accumulation of B by tolerant genotypes in both roots and shoots. Results from experiments of uptake kinetics indicate that control of B uptake is a non-metabolic process. The response of wheat to high B supply is under the control of several major additive genes, one of which has been located to chromosome 4A.
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  • 100
    ISSN: 1573-1561
    Keywords: Hessian fly ; Mayetiola destructor ; Diptera ; Cecidomyiidae ; oviposition stimulants ; wheat ; rye ; barley ; oat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract More than twice the number of mated female Hessian flies,Mayetiola destructor (Say) entered a zone within 1 cm of a paper strip treated with one plant equivalent (PE) of a chloroform extract of wheat foliar waxes compared to a strip treated with solvent only; females also stayed six times longer and laid 10 times more eggs on the strip treated with the wheat extract. Column chromatographic fractionation of the wheat extract and application of these fractions onto filter paper strips showed four fractions elicited significant numbers of eggs to be laid. Single, binary, and tertiary combinations of three of these fractions (two of the four fractions apparently contained similar compounds) were tested. The greatest numbers of eggs were laid on strips treated with the tertiary combination or the binary combination conaining the two most active fractions (3 and 6); three times the number of eggs were laid on strips treated with this binary combination than the sum of eggs laid on strips treated with these two fractions separately. A comparison of grasses and their extracts showed female Hessian flies laid greater numbers of eggs on wheat or rye than on barley or oat. Fractionated barley and oat extracts were tested for activity as for wheat, and a similar pattern was observed, i.e., the greatest numbers of eggs were laid on fractions 3 and 6. Dose-response tests, using these two fractions of wheat, barley, or oat showed the same threshold of activity for fraction 3 for all three extracts, i.e., 2 PE. In contrast, fraction 6 of wheat was active at the lowest dosage tested, 0.25 PE, while the same fraction of either barley or oat was not active until tested at a dosage of 2 PE. It appears that (at least) two chemicals in the foliar waxes of these grasses influence ovipositional behavior of female Hessian flies. Furthermore, given the similar foliar chemistry of these grasses and the strong synergistic interaction between fractions 3 and 6 shown for wheat extract, it is likely that the ovipositional preferences exhibited by female Hessian flies towards these grasses may be explained by quantitative differences in the amount(s) of the active chemical(s) in their respective fraction 6 (most polar fraction tested).
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