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Biomedical subjects

B Bach

Publications and source records attributed to B Bach.

At least 37 records · Page 2Linked to original sources
PubMed1985

Exogenous glutathione induces sister chromatid exchanges, clastogenicity and endoreduplication in V79-E Chinese hamster cells.

Glutathione (GSH) dissolved in Eagle's MEM and added to cultures of V79-E cells in concentrations between 2.5 X 10(-4) and 10(-3) moles/l for 1 h induces a dose-dependent cell cycle delay, sister chromatid exchanges and clastogenic damage. 7-8% of the metaphases showed endoreduplication at a recovery phase of 25 and 30 h after treatment with 10(-3) moles/l GSH. Higher concentrations were lethal. The highest tolerated dose corresponds to the intracellular GSH level in V79-E cells. In the same range of concentrations, glutathione disulfide was inactive. Endoreduplication induction by GSH is G2-phase specific and endoreduplication metaphases show a reduced occurrence of single SCEs when extrapolated to the diploid complement. The adverse effects of GSH are independent of the presence of serum in the culture fluid but completely abolished when the treatment is performed in Hank's solution instead of MEM. The mechanism of genotoxicity of exogenous GSH is discussed but, at present, no pertinent explanation can be given.

Animals↗
PubMed1985

Detection of a deuterium isotope effect in di- and trisubstituted alkylphenylnitrosoureas. An SCE study in Chinese hamster V79-E cells.

The genotoxicity of 1-methyl-3-phenyl-1-nitrosourea (MPNU), 1-methyl-3-(p-chlorophenyl)-1-nitrosourea (C1-MPNU), 1-ethyl-3-phenyl-1-nitrosourea (EPNU), 1,3-dimethyl-3-phenyl-1-nitrosourea (DMPNU) and their derivatives substituted by deuterium in different positions was studied using sister chromatid exchange (SCE) induction in Chinese hamster V79-E cells. Deuterium substitution in the 1-methyl group of MPNU (MPNU-d3) and C1-MPNU (C1-MPNU-d3) diminished the SCE-inducing capacity by 20-30% and by 30-40% in DMPNU (DMPNU-d3B). There was no altered SCE activity detected when the phenyl group of MPNU (MPNU-d5) or the 3-methyl group of DMPNU (DMPNU-d3A) was deuterium labeled. No isotope effect was detected in deuterated EPNU derivatives, presumably due to the instability of these compounds. It is surmised that the easier delocalization of the positive charge in the deuterated alkyl diazonium ion causes a diminished reactivity and therefore influences the type and amount of DNA alkylation. Furthermore, the experiments with DMPNU and its derivatives revealed that, in contrast to mono- and disubstituted nitrosoureas, the biological activities of these very stable trisubstituted nitrosoureas are strongly influenced by a serum factor in the culture fluid.

Animals↗
PubMed1982

Serum antibodies and immunoglobulins in smokers and nonsmokers.

Antibodies to antigens in humidifier water were detected by double immunodiffusion in 30 of 63 (47.6%) persons who were exposed to aerosols from a water humidification unit in a cigar plant, whereas no antibodies could be detected in 49 unexposed blood donors (P less than 0.001). The presence of antibodies could not be related to fever or pulmonary symptoms (cough, expectoration, dyspnoe). Antibodies were found in 14 (93.3%) of 15 nonsmokers and in only 13 (31.7%) of 41 smokers (P less than 0.001), and the titres were highest in nonsmokers. Serum IgG and IgA levels were higher in nonsmokers than in smokers, and the variances within the groups were significantly different (F less than 0.05 and F less than 0.05, respectively). The mean serum IgM values were not significantly different in the two groups. Antibodies to Candida albicans and Escherichia coli 04 and 075 were detected with equal prevalences and titres in smokers and nonsmokers. These findings suggest that tobacco smoking may suppress the humoral immune response to inhaled antigens but not to antigens which are supposed to be absorbed through membranes other than those of the bronchopulmonary system. They may partly explain the reported increased incidence of allergic alveolitis in nonsmokers.

Adolescent↗
PubMed1981

[Early jaundice after orthotopic liver transplantation. The role of ischaemia (author's transl)].

The purpose of this experimental study was to identify the cause of early cholestatic jaundice occurring after orthotopic liver transplantation. The role of ischaemia was investigated in dogs undergoing auto-transplantation of the liver preserved for two hours. The animals developed early cholestasis with lesions that were markedly different from the graft-rejection lesions observed in a control group, being restricted to the cells and canaliculi of the central lobular area. The results of this work have made it possible to avoid overdosage with immunosuppressive drugs in a patient who had recently undergone orthotopic liver transplantation.

Animals↗
PubMed1979

Kinetics of propylthiouracil in the elderly.

The pharmakokinetics of propylthiouracil was evaluated in 9 elderly patients and compared to previous results from 6 younger subjects. By giving the drug both by the intravenous and oral route of administration it was possible to estimate the rate and extent of bioavailability. The various kinetic parameters were calculated according to a two-compartment model by use of two different methods: a graphical hand drawn one and by a special developed computer program based on a least squares minimalisation. While no significant differences could be demonstrated between the two age groups concerning volumes of distribution, clearance and extent of absorption, a large difference was found with regard to the absorption rate constant ka, which was about 3 times higher in the younger than in the elderly subjects, presumably due a reduced gastric emptying time. Considering the comparison between the two methods of calculations all the kinetics parameters were similar except ka and the slow disposition rate constant betw which were underestimated by the graphical method. It is concluded that no-age dependent changes exist concerning the kinetics of propylthiouracil except for a decreased rate of absorption. Graphical methods in pharmacokinetics are useful in obtaining distribution and elimination data but seem often biased for the evaluation of absorption rate constants.

Age Factors↗