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Biomedical subjects

M Kirsch-Volders

Publications and source records attributed to M Kirsch-Volders.

117 records · Page 7Linked to original sources
PubMed1975

Fragmentation of purified mammalian DNA molecules by ultrasound below human therapeutic doses.

Because of the increasing medical use of ultrasound, especially in obstetrical diagnosis, it has become important to check its genetic harmlessness. Purified calf thymus DNA in solution was exposed to both therapeutic and obstetrical diagnostic doses of ultrasound. Intensities lower than those used in therapy have a drastic effect on purified DNA in solution, although intensities used in obstetrical diagnosis caused no visible effect.

Animals↗
PubMed1975

Relative position of trypsin banded homologous chromosomes in human (female) metaphase figures.

"Generalized distances" between centromeres were statistically analyzed (chi2 test) on 50 normal female trypsin-banded metaphase figures. This study revealed that the homologous chromosomes of the pairs 13, 17, 14, and 21 lie closer together than would be expected by a reference distribution, and this in a statistically significant way. The same relative position was demonstrated for the chromosome groups 13-14, 13-21, 14-21, 15-22, and 14-22. Evidences were collected that also showed that homologous chromosomes of the pairs 1, 19, and 20 and the chromosome groups 15-21, 13-15, and 18-20 tend to lie closer together. Giving a functional interpretation to the phenomenon of non-random distribution of chromosomes in metaphase figures, it may be suggested that the chromosomes 13, 14, and 21 are involved in the organization of the human nucleolar organizers, more frequently than the other D- and G-group chromosomes.

Cell Nucleus↗
PubMed1972

Characterization of yolk DNA from Xenopus laevis oocytes ovulated in vitro.

High molecular weight DNA was isolated from the yolk platelets of Xenopus laevis oocytes ovulated in vitro. Yolk DNA has the same buoyant density in CsCl gradients as mitochondrial and nuclear DNAs, and, like them, it is double-stranded. Yolk DNA behaves like nuclear DNA, and not like mitochondrial DNA, upon renaturation after denaturation. The molecules are always linear. Cytochemical and biochemical controls preclude the possibility that the yolk DNA might be contaminated by nuclear or mitochondrial DNA. We conclude that the yolk DNA is an endogenous component of the yolk platelets.

Ambystoma↗
PubMedDate not supplied

Comparative in vitro cytogenetic studies in mercury-exposed human lymphocytes.

As part of a long-term cytogenetic research project on mercury, we studied the in vitro clastogenic capacity of HgCl2 and CH3HgCl as well as their influence on chromosome segregation by means of a computer-aided chromosome distribution study in metaphase plates. As in other in vitro studies published elsewhere, we exposed human peripheral blood lymphocytes to different concentrations of the mercury compound during a limited period of the pre-DNA synthetic stage (G1-S) or from that stage up to mitosis (G1-M). For both exposure periods and both mercury compounds we observed a rather important clastogenic effect as well as a dissociation of the (normally highly associated) acrocentrics. The results do indicate, in conjunction with previously published data, that mercury compounds alter the chromosome segregation at lower concentrations than those observed for clastogenicity. Moreover, the effects on chromosome segregation are not necessarily due to binding to spindle proteins. Binding to--and inactivation of RNA polymerase I may for example be another mechanism of action which is more important for the inorganic form of mercury than for the organic form.

Adult↗
PubMedDate not supplied

Differential staining of chromosomes and spindle cannot be used as an assay to determine the effect of cancer promoters on primary cultures of human fibroblasts.

The differential staining technique allows simultaneous visualization of chromosomes and spindle fibers. The relative sensitivity of this test for chemicals with high tumor-promoting activity (TPA and iodoacetic acid) or for low tumor-promoting chemicals (4 beta-PDD and alpha-phorbol) was analyzed. Moreover, to ensure a complementary reference system, metals with possible mutagenic (As greater than Hg greater than Cd) and carcinogenic (As greater than Cd = Hg) properties were tested in parallel. As and Hg, which are known as spindle poisons, do induce, as expected, a disaggregation of the spindle fibers; with Cd, no clear-cut disappearance of the spindle is observed. As far as the cancer promoters are concerned, there is no evidence that their ability to induce mitotic aneuploidy in yeast would be confirmed by the induction of spindle disappearance and/or abnormal chromosome segregation in primary cultures of human fibroblasts.

Carcinogens↗
PubMedDate not supplied

Stimulation of human lymphocytes in vitro by purified autologous DNA.

Addition of increasing concentrations of autologous DNA, but not of allogeneic DNA, in culture media of human lymphocytes induces a parallel increase of thymidine incorporation into leucocytes and of lymphocytes transformation into blast cells. Specificity of DNA action was analysed by different DNase and RNase treatments. DNase or RNase alone neither stimulates blastic transformation of lymphocytes and incorporation of thymidine into leucocytes, nor inhibits PHA-induced stimulations of these cells. However Dnase--but almost not RNase--clearly inhibits thymidine incorporation and blast transformation induced by autologous DNA.

Carbon Radioisotopes↗