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Biomedical subjects

S Kuhn

Publications and source records attributed to S Kuhn.

69 records · Page 4Linked to original sources
PubMed1986

The effects of diabetes mellitus, exercise, and single doses of biguanides upon lactate metabolism in man.

The polymorphism of phenformin oxidation has been investigated in 103 non-insulin-dependent (Type II) diabetics. The frequency distribution was clearly bimodal and 14 poor metabolisers were identified. The frequency of the recessive allele (0.369) was not significantly different from that found previously in non-diabetics. Six of the extensive metabolisers of phenformin were matched for age, sex and oxidizer phenotype with non-diabetic controls. All subjects underwent a standard 3-min exercise test, using a bicycle ergometer, after which plasma lactate concentration was monitored for 90 min. There was no significant difference between groups in lactate accumulation or elimination. Ten extensive metabolisers, ten poor metabolisers and seven non-diabetics (matched for age, sex and phenotype with seven of the diabetic extensive metabolisers) were challenged with a fasting oral dose of phenformin (50 mg), after which plasma lactate, and blood pyruvate and glucose concentrations were monitored for 4 h. A further ten diabetics (five extensive and five poor metabolisers of phenformin) received a single dose of metformin (1 g) following an identical protocol. No significant changes were observed in any group.

Adult↗
PubMed1985

The rise and fall of serum theophylline concentration: a comparison of sustained-release formulations in volunteers with rapid theophylline clearance.

The pharmacokinetics of four sustained-release formulations of theophylline have been examined after single doses (Nuelin SA, Phyllocontin, Slo-phyllin and Theo-Dur) and at steady-state (Phyllocontin, Theo-Dur) in six healthy adult volunteers, selected because they all eliminated theophylline rapidly after an intravenous dose of aminophylline. After a single dose of Theo-Dur, the peak concentration of theophylline was smaller and occurred later than after single doses of Nuelin SA, Phyllocontin and Slo-phyllin, suggesting that absorption occurs over a longer period. The systemic availability of theophylline was virtually complete after all four formulations. After repeated 12-hourly dosing to steady-state, and adjustment of dose to achieve trough concentrations of between 5 and 10 mg l-1 (28-55 mumol l-1), theophylline concentration fluctuated to a significantly greater extent within a dose interval when the subjects were taking Phyllocontin than when they were taking Theo-Dur.

Administration, Oral↗
PubMed1985

A comparative study of the bioavailability of five different phenytoin preparations.

The concentration of phenytoin in saliva has been measured in 8 healthy volunteers at intervals after an intravenous dose and after single oral doses of five formulations commercially available in the United Kingdom. The six doses (all 300 mg) were given in random order and at least one week apart. There were no significant differences in the mean values of the peak saliva concentration, the time-to-peak and the area under the saliva concentration-time curve between the five oral formulations. The absolute bioavailability of phenytoin varied between 68 and 74%.

Adult↗
PubMed1984

Immunochemistry of I/i-active oligo- and polyglycosylceramides from rabbit erythrocyte membranes. Determination of branching patterns of a ceramide pentadecasaccharide by 1H nuclear magnetic resonance.

1H NMR spectra of the ceramide hexasaccharide obtained after the removal of the terminal alpha-Gal and subterminal beta-Gal residues from the ceramide decasaccharide, Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-3)[Gal(alpha 1-3)Gal(beta 1-4)GlcNAc (beta 1-6)]Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer, showed that terminal and internal GlcNAc residues are differentiated by their chemical shifts. This finding enabled us to determine the primary structure of the title compound as Gal(alpha 1-3)Gal(beta 1-4)GlcNAc (beta 1-3)[Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-6)]Gal(beta 1-4)GlcNAc (beta 1-3)[Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-6)]Gal(beta 1-4)GlcNAc (beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer. Alternative branching of this oligosaccharide chain was excluded since the removal of all terminal alpha-Gal and penultimate beta-Gal residues yielded a ceramide nonasaccharide containing one terminal and two internal 1----3-linked GlcNAc residues, as well as two terminal 1----6-linked GlcNAc units. The intermediate degradation products of the ceramide deca- and pentadecasaccharides , viz. the ceramide octa- and dodecasaccharide , obtained by the removal of alpha-Gal residues only, as well as the linear ceramide heptasaccharide, Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-3) Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer, and ceramide hexasaccharide, Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)GlcNAc (beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer, were also investigated. The usefulness of the glycosylation-induced chemical shifts is discussed.

Animals↗
PubMed1984

The comparative beta-adrenoceptor blocking effects of penbutolol, atenolol and sustained-release metoprolol in healthy volunteers.

The effects of penbutolol (40 mg), atenolol (100 mg) and sustained-release metoprolol (metoprolol SA) (200 mg) upon heart rate (HR) and blood pressure (BP) at rest and during bicycle ergometer exercise, have been compared in 12 healthy young men using a double-blind crossover design. Measurements of each drug's effect were made before and at 3, 10 and 24 h after a single dose, and again at 24 h after the last of seven consecutive daily doses. Resting HR and systolic BP were reduced to an equivalent extent by all three drugs. During the third minute of exercise, the effects of penbutolol and atenolol upon HR and systolic BP were consistently similar and greater than those of metoprolol SA.

Adolescent↗
PubMed1977

Successful chemoprophylaxis for Pneumocystis carinii pneumonitis.

In a randomized, double-blind, placebocontrolled study to evaluate the efficacy of trimethoprim-sulfamethoxazole for the prevention of Pneumocystis carinii pneumonia, we studied 160 patients with cancer who were at high risk for this pneumonia over a two-year period. Seventeen of the 80 patients receiving a placebo acquired P. carinii pneumonitis, whereas none of the 80 given 150 mg of trimethoprim and 750 mg of sulfamethoxazole per square meter per day had the infection P less than 0.01). Bacterial sepsis, pneumonia other than that caused by P. carinii, acute otitis media, upper-respiratory-tract infections, sinusitis and cellulitis occurred less frequently in recipients of the drug than in the placebo group (P less than 0.01 in each case). Oral candidiasis was the only adverse effect ecountered from trimethoprim-sulfamethoxazole administration. The study shows the combination to be highly effective in the prevention of P. carinii pneumonitis.

Adolescent↗
PubMedDate not supplied

Transition to alcohol dependence: clinical and neurobiological considerations.

The transition to alcohol dependence is supposed to occur during a critical period that begins with increased drinking and ends with a loss of control. This process may last about 3 to 4 years, and is modified by gender and accelerated by premorbid traits (e.g., novelty-seeking) and comorbid disorders (e.g., dissocial personality disorders according to ICD-10). Genetic disposition, environmental influences (e.g., stress), and sensitization by exposure are factors implicated in dependence that alter brain functions, some possibly in an irreversible way. Underlying neurobiological mechanisms that may have different time patterns are beginning to be characterized on a systemic, cellular, and molecular level. Repeated free choices of the rewarding compound seem to be necessary for the transition to dependence.

Adult↗