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Biomedical subjects

S Wolff

Publications and source records attributed to S Wolff.

222 records · Page 13Linked to original sources
PubMedDate not supplied

Adaptive response of human lymphocytes for the repair of radon-induced chromosomal damage.

In human lymphocytes low doses of X-rays can decrease the number of chromatid deletions induced by subsequent high doses of sparsely ionizing X-rays. Because of the concern with the carcinogenic effects of low doses of alpha-particles from radon in homes, experiments were carried out to see if low doses of X-rays could also decrease the yield of chromosomal aberrations induced by subsequent exposure to radon. Human peripheral blood lymphocytes were irradiated with low doses of X-rays (2 cGy) at 48 h of culture, exposed to radon at 72 h of culture, and analyzed for the presence of chromatid aberrations at subsequent intervals. The frequency of chromatid aberrations induced by radon alone increased with time after exposure, indicating exaggerated differences in the stage sensitivity of cell cycle stages to high-LET radiation. Furthermore, the numbers of aberrations per cell did not follow a Poisson distribution but were over dispersed, as might be expected since high-LET radiations have a high relative biological effectiveness compared with low-LET radiations. Nevertheless, lymphocytes exposed to 2 cGy of X-rays before radon exposure contained approximately one-half the number of chromatid deletions compared with lymphocytes treated with radon alone and analyzed at the same time. Thus, the putative chromosomal repair mechanism induced by low doses of sparsely ionizing radiation is also effective in reducing chromosomal aberrations induced by radon, which hitherto had been thought to be relatively independent of repair processes.

Adaptation, Physiological↗
PubMedDate not supplied

Re-analysis of radiation-induced specific locus mutations in the mouse.

A re-analysis of published data on mouse mutation rates induced by X and gamma rays suggests that the kinetics of induction can be analysed by fitting the data to a parabolic curve. We interpret this to mean that a substantial proportion of the induced mutations results from gross chromosomal changes such as deletions, some of which are one-track and some of which are two-track. This analysis is based on the assumption that the shape of the dose curve, which in the female is concave upward, reflects the manner in which the mutations are induced rather than representing a one-track (linear) curve whose shape has been modified by differential repair.

Animals↗
PubMedDate not supplied

Nitroxyl spin label contrast enhancers for magnetic resonance imaging. Studies of acute toxicity and mutagenesis.

Two nitroxyl spin label (NSL) compounds that are used experimentally as in vivo contrast enhancers in magnetic resonance (MR) imaging were tested for acute toxicity in rats and for genotoxic effects in cell cultures. These compounds, 2,2,5,5-tetramethyl-1-pyrrolidinyl-oxy-3-carboxylic acid (PCA) and 2,2,6,6-tetramethyl-1-oxido-4-piperidinyl-1-succinic acid (TES) and their hydroxylamine and amine derivatives did not induce sister chromatid exchanges or mutations in Chinese hamster ovary cells at the HGPRT or Na+/K+ ATPase loci. The acute LD50 doses in rats for PCA and TES are 15.1 mmol/kg or greater, suggesting relatively high tolerance.

Animals↗
PubMedDate not supplied

[The forensic expert as author--text construction of psychiatric evaluation].

Some aspects of text construction of psychiatric expert opinion are discussed. Based upon the analysis of his own data, the author attempts to show that expert opinions represent conventionalized forms of communication which not only result in certain types of problems of representation, but also allow for different types of representation.

Expert Testimony↗