Biomedical subjects
Publications and source records attributed to A Kolman.
The radioprotective effect of an extract of Spirulina platensis has been studied using the micronucleus test in polychromatic erythrocytes of bone marrow of mice. In this system the extract caused a significant reduction of the micronucleus frequencies induced by gamma-radiation.
A dose-dependent transforming ability of the direct-acting alkylating agent, ethylene oxide (EtO), was demonstrated in C3H/10T1/2 mouse embryo fibroblasts. Morphologically transformed colonies were observed 5-6 weeks after the treatment with EtO. The transforming effectiveness of EtO was compared with that of gamma-radiation, and the rad-equivalence of EtO was calculated to be approximately 90 rad/mMh. This value is consistent with earlier estimates based on induced mutation in various biological systems and thus indicates the applicability of the C3H/10T1/2 cell system in the risk estimation of human exposure to genotoxic compounds.
The genotoxic effectiveness of ethylene oxide is compared with that of gamma-radiation, as measured by induced transformation of C3H 10T1/2 mouse embryo fibroblasts. The resultant value of the quality factor, Q approximately 80 rad/mM X h, is compatible with earlier data on mutation and other endpoints in various test systems. This quality factor can thus be used to estimate the risk of exposures to ethylene oxide or its precursor, ethene, on the basis of human doses monitored by haemoglobin adducts.
Mutagenicity of ethylene oxide in Escherichia coli B strains with different repair capacities was studied. Deficiencies in excision repair (uvrA, polA) led to a considerable increase in mutation frequency compared with that in the wild-type strain and in strains deficient in error-prone repair (recA, lexA).
5'-Deoxy-5'-(methylthio)adenosine (MTA) alone and in combination with methionine was found to increase frequencies of background HGPRT mutation and SCE in V79 Chinese hamster cells. The same agents exert a comutagenic action on these effects as well as upon mutation induction in Escherichia coli stain AB1157 (but not in its non-adaptable derivative ada-6) following treatment with N-methyl-N-nitrosourea (MNU). MTA plus methionine also enhanced the lethal action of MNU on hamster cells. The effects observed may tentatively be ascribed to hypomethylation due to inhibition of DNA methylase by MTA.
Cysteamine (MEA) is comutagenic to methylnitrosourea (MNU) in E. coli AB 1157 but not in the nonadaptable mutant derivative ada-6 of that strain. The comutagenic action of MEA was eliminated by cysteine at low concentrations, which also lowered mutation frequencies in AB1157 but not in ada-6. In model experiments it was shown that cysteine counteracted the inhibition by MEA of beta-galactosidase induction in both bacterium strains. The comutagenic action of MEA is interpreted as being due to an inhibition of induction of methyltransferase during treatment with MNU.
Explore the source record for details and available documents.
The influence of uvrB and umuC genes on the induction of lacI- mutants and nonsense mutants by ethylene oxide (EtO) in the lacI gene of E. coli was studied. The uvrB mutation was characterized by much higher mutation frequencies. In contrast the umuC mutation does not significantly affect the induction kinetics. Thus mutation by EtO is enhanced by the lack of excision repair but not influenced by error-prone repair.
The influence of pre-exposure to low doses of ethylene oxide (EtO) on the frequency of leu+ revertants in the E. coli strain, WU36-10, and its excision-repair-deficient mutant, WU36-10-89, after treatment with high doses of EtO, was studied. Low doses had an adaptive effect in both strains with respect to high doses of EtO which was manifested by a decreased number of revertants and lower lethality.
The interaction of UV-irradiation and ethylene oxide (EtO) on forward mutation frequencies in the lacI gene of E. coli strains 3835 and 3951 and on the frequency of leu+ revertants in E. coli WU36-10-89 were studied. Pre-exposure to low doses of UV-light with the following treatment by low and intermediate doses of EtO showed lack of additive effect in the mutagenic response in all strains studied. The number of mutants actually obtained in the respective experiments was much lower than the additive model predicted.
Explore the source record for details and available documents.
As compared to control-groups of rheumatoid arthritis and chronic non-inflammatory low back pain, over a hundred polyclinical patients suffering from ankylosing spondylitis were assessed with respect to several personality characteristics by psychological testing and proved to be relatively sthenic and educated. In trying to explain these personality features some disease-related factors seem to be relevant in ankylosing spondylitis: a relatively mild course of disease, the relief of complaints by exercise and a long pre-diagnostic period.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Colonies of a non-acid-fast mutant of Mycobacterium phlei--termed "PN--bb"--were examined by scanning electron microscopy of gold-sputted whole colonies and by transmission electron microscopy of thin sections. Inspection of the colonies before and after preparation showed that the fixed colonies had retained their original appearance. Colonies are about 2-5 mm in height and width. They are made up of converging ridges forming a cone. These ridges consists of rounded bodies which are made up of clustered cells. The top of the cone consists of small, rugged, irregular structures. Thin sections show that the cells are arranged close together, without interconnections but with some electron-dense material between them. The colony is covered with a layer of unknown composition.
Study of lipid and DNA, biochemical tests and phage typing performed on the strain PA previously labelled Mycobacterium phlei, lead to the conclusion that this strain belongs to the species M. smegmatis. Parallel studies performed on strain PN, isolated from a culture of strain PA, as well as DNA homology percentage of the two strains, do not support the assumption that strain PN could have resulted from a mutation of strain PA Strain PN produces mycolic acids similar to those found in Rhodococcus bronchialis; the few biological tests applied quite agree with such a classification.