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Biomedical subjects

R Warzok

Publications and source records attributed to R Warzok.

At least 73 records · Page 4Linked to original sources
PubMed1981

The influence of sodium selenite on tumor induction by methylnitrosourea (MNU) in rats.

The effect of sodium selenite on tumor induction by MNU was studied in 3 groups of 40 WE rats each. Group I received 10 intraperitoneal injections of 20 mg/kg b. w. MNU in intervals of 4 weeks and beginning with the 1st administration 4 ppm sodium selenite in the drinking water. Rats of group II and III were given only MNU or selenite, respectively. A slight but statistically not significant increase of tumors was found in group I as compared with group II. In group III tumors did not occur. Problems of the anticarcinogenic action of sodium selenite and other antioxidants are discussed.

Animals↗
PubMed1981

[Localization of brain tumors in autopsy. Part I: Tumors of the temporal lobe].

Among the 54946 post-mortem examinations carried out by the Pathological Institute of the Medical Academy of Erfurt in the years 1953 to 1976 with a total of 1491 DNS-tumours (2.7%), the temporal lobe was involved in the following 10 types of tumours: glioblastoma, ependymoma, oligodendroglioma, plexus papilloma, tumour-like gliosis, sarcoma, angioma and angioblastoma, epidermoid tumour, teratoma. Only tumours that had formed in the cerebral tissue proper were evaluated, so that meningiomas and other tumours of the meninges or tumours of the meninges in the middle cranial fossa were left out of consideration. In a total of 949 cases of the above mentioned 10 tumours types, the temporal lobe was involved in 327 (34.5%) cases; these were mainly astrocytomas and glioblastomas (86.5%). Only 63 of the 327 tumours (19.3%) were exclusively located in the temporal lobe. The age peak of the occurrence of temporal lobe tumours was in the 6th decennium. The male showed with 55.4 per cent a slightly greater incidence. CLinically, the left-sided temporal lobe tumours with 79 per cent of the observations were found more frequently than the right-sided ones (67%). Accordingly, left-sided tumours were operated on more frequently (49%) than tumours on the right-hand side (40%).

Adult↗
PubMed1980

Differences in carcinogenicity after transplacental and postnatal administration of drugs and pesticides.

Comparative studies of the carcinogenic activity of procarbazine, methylphenylnitrosourea and ethylenethiourea after transplacental and postnatal administration showed that there were marked differences in frequency and spectrum of tumors induced. Possible causes of these differences are briefly discussed. It is suggested that transplacental experiments can provide special advantages in testing drugs and environmental chemicals for potential carcinogenicity and should be included in test programs.

Animals↗
PubMed1980

Nitrosated urea pesticide metabolites and other nitrosamides. Activity in clastogenicity and SCE assays, and aberration kinetics in Chinese hamster V79-E cells.

The nitrosoureas 1-methyl-1-nitroso-3-phenylurea, 1-ethyl-1-nitroso-3-phenylurea, 1-methyl-1-nitroso-3-(p-fluorophenyl)urea, 1-methyl-1-nitroso-3-(p-chlorophenyl)urea, and 1-methyl-1-nitroso-3-(p-bromophenyl)urea, as well as their non-nitrosated parent compounds, were checked for induction of chromosomal aberrations and sister-chromatid exchanges in V79-E cells without metabolic activation in vitro. For comparison, methylnitrosourea, ethylnitrosourea and nitrosocarbaryl were included in this study. Whereas the non-nitrosated agents were inactive, the nitroso derivatives were potent clastogens and inducers of SCEs. Clastogenicity parallels SCE induction, but the latter assay is about 10 times more sensitive (based on concentration of substance) than the clastogenicity assay. The dependence of aberration frequency on sampling time, which was studied for 5 nitroso compounds, revealed striking differences. As demonstrated by differential chromatid staining, the lag phase until maximal aberration rates may cover more than 2 cell cycles. Preventive oncological aspects of these nitrosamides and the mechanism of aberration kinetics are discussed.

Animals↗
PubMed1980

Physico-chemical, mutagenic and carcinogenic properties of nitrosated urea herbicide metabolites.

Alkylating activities, rates of decomposition, partition coefficients (octanol/water) and sister chromatid exchanges of several N-nitroso compounds, formed by nitrosation of pesticide metabolites or closely related substances, were determined. The carcinogenic activity of two compounds was investigated in rats. The measured parameters were compared in a search for possible correlations.

Animals↗
PubMed1979

Tumors of the rat kidney induced by nitrosourea compounds.

Apart from other lesions, 51 renal neoplasms were induced in rats by administration of methylethy-, dimethyl- and phenylmethylnitrosourea. 3 tumors originated from the renal pelvis and were classified as transitional cell papilloma (1) or transitional cell carcinoma (2). 48 neoplasms were considered as "mesenchymal tumors". These growths were regarded as rat kidney specific tumors. They display a wide spectrum of histological structures: spindle cells which are capable to differentiate into smooth muscle cells, fibroblasts, angioblasts, fat cells, and even into cartilage thus forming the typical microscopical features which are completed by the tendency of mesenchymal cells to swirl around preexisting renal tubules in several closely investing layers. As the cell of origin is not yet established the term "mesenchymal tumor" seems to be the most suitable one. There is no basis for classifying these tumor as nephroblastomas and the two entities should be strictly separated.

Animals↗
PubMed1979

Late neuropathological findings after acute rubella encephalitis.

Neurophathological findings are reported in a 15-year-old boy who died 8 months after acute rubella encephalitis. There are widespread bilateral necroses in large areas of the cerebral cortex with a diffuse macroglial and microglial reaction. In basal ganglia, degenerative changes and a more or less pronounced rarefication of nerve cells as well as very small cystic areas and glial scars are observed. In the white matter, neither foci of demyelination nor perivascular cuffings nor focal gliosis occurred. The results are compared with other observations in the literature. It is concluded that rubells encephalitis is a disease of a variety of pathogenetic mechanisms and has a variety of clinical and morhpological features. It may evidently be caused by direct viral invasion of the CNS or by hypersensitivity reaction.

Adolescent↗
PubMed1978

Use of human-liver microsomes from kidney-transplant donors for the induction of chromatid aberrations and sister-chromatid exchanges by means of pre-carcinogens in Chinese hamster cells in vitro.

Samples of two human livers taken during operation of kidney donor patients were processed for microsome fractions and used for metabolization of cyclophosphamide (CP) and dimethylnitrosamine (DMN) in combination with the NADPH-generating system. Rat-liver microsomes were checked for comparison. Induction of chromatid aberrations and sister-chromatid exchanges in a newly isolated clone of Chinese hamster fibroblasts served as indicators of activity. Human S-9 fractions standardized on protein content showed strong variations of CP and DMN activation. Whereas liver microsomes of one patient (who also suffered from Gaucher's disease) were highly active for both pre-carcinogens and metabolized DMN at the same level as the uninduced rat-liver microsomes, the S-9 fraction from the second patient failed to activate CP, but was distinctly positive for DMN. It is suggested that samples of liver and other organs of renal transplant donors might be a practicable source of freshly prepared human microsome fractions usable in biochemical, genetic and carcinogenetic studies. Problems concerning the extrapolation of results are discussed.

Biotransformation↗