PubMed Health⌕ Search

Biomedical subjects

H S Taper

Publications and source records attributed to H S Taper.

At least 55 records · Page 3Linked to original sources
PubMed1979

Evaluation of the validity of the histochemical lead nitrate technique for alkaline and acid deoxyribonuclease.

The results of several tests and the characteristic morphological distribution of the enzymatic activity appeared to be in favor of the validity and specificity of the histochemical lead nitrate technique for alkaline and acid deoxyribonuclease (DNAse) detection. These tests included thermal inhibition, omission of substrate, use of different chemical inhibitors and the reproduction of histochemical staining on Coujard's slides. Most of these results were in conformity with the biochemical data gathered from literature. Topographically selective inhibition of alkaline or acid DNAse by different factors suggested that there might exist two kinds of alkaline or acid DNase--one cytoplasmic and the other one nuclear. The whole histochemical procedure produced relatively small loss of alkaline and acid DNAse activities as verified by biochemical methods.

Animals↗
PubMed1978

The effect of estradiol-17-phenylpropionate and estradiol benzoate on N-nitrosomorpholine-induced liver carcinogenesis in ovariectomized female rats.

The influence of synthetic estrogens on the N-nitrosomorpholine (NNM)-induced liver carcinogenesis in ovariectomized young adult female rats was investigated and compared to rats which received only the carcinogen or estrogens. Estrogens when chronically administered after the cessation of carcinogen treatment increased the carcinogenic effect of NNM. In such conditioned animals the number of nodules per number of rats was 23/31, that of hepato-cellular carcinomas 9/31, whereas in animals which received only the hepato-carcinogen the incidence of nodules and carcinomas in liver was respectively 11/31 and 3/31. Higher incidence of benign and malignant tumors in other organs was also observed in these animals. Rats which received a single dose of estrogens simultaneously with NNM developed slightly fewer tumors in liver and in other organs. Since under my experimental conditions the long-term treatment with synthetic estrogens alone did not induce any focus, nodule or hepatocellular carcinoma in the liver. I suggest that the estrogens were acting rather as tumor promotors than true initiators of liver carcinogenesis.

Animals↗
PubMed1977

Induction of the deficient acid DNAse activity in mouse interfollicular epidermis by croton oil as a possible tumor promoting mechanism.

Histochemical activity of acid DNAse, intensity of nucleic acid staining and histological alterations in mouse interfollicular epidermis (I.F.E.) were investigated after a single dose or after chronic topical administration of two hyperplastic agents, of which one (croton oil) was a potent tumor promotor, and the other one (podophyllin) did not promote skin carcinogenesis. Podophyllin induced intense uniform I.F.E. hyperplasia without any proliferation of poorly differentiated basal cells, without increased nucleic acid staining and without any appreciably decreased acid DNAse activity. On the other hand, croton oil (as well as TPA) produced almost immediate, distinct hyperplasia of poorly differentiated basal cells with increased intensity in the staining of both nucleic acids and nearly complete deficiency in acid DNAse activity. Similar histochemical and histological patterns were observed at the sites of wounding hyperplasia in untreated control mice. Such wounding hyperplasia was thought also to be a tumor promoting factor. It was suggested that the decrease in acid DNAse activity which occurred almost immediately after administration of potent tumor promoters and which could not be induced by a hyperplastic agent without tumor promoting action may have a particular importance in the mechanisms of tumor promotion.

Animals↗
PubMed1976

Histochemical correlation between glycogen, nucleic acids and nucleases in pre-neoplastic and neoplastic lesions of rat liver after short-term administration of N-nitrosomorpholine.

After 7 weeks of oral administration of the carcinogen N-nitrosomorpholine (12 mg NNM ad 100 ml of drinking water) to male rats, marked hepatocellular changes were found predominantly in the centers of the lobules. These were loss of glycogen, disorganisation of the basophilic bodies and, sometimes, loss of cytoplasmic basophilia or pyroninophilia, necrotic cells and increase in the activity of acid DNAse and RNAse. These centrilobular alterations were reversible after withdrawal of the carcinogen. They are, therefore, attributed to the nonspecific-toxic effect of the carcinogen. In peripheral and midzonal regions of the lobules basically different cellular changes appeared which were unimportant during the phase of intoxication, but became prominent after cessation of the carcinogenic treatment. These lesions were: excessive storage of glycogen, displacement of basophilic bodies and an increase in cytoplasmic acidophilia. The hepatocytes showing these cytoplasmic changes initially formed foci. Neoplastic nodules and frank hepatocellular carcinomas developed later. During these later stages of the experiment both the foci and the nodules consisted of 4 main types of altered hepatocytes: 1) "clear" glycogen storage cells, 2) acidophilic cells, 3) vacuolated (fat storing) cells, 4) basophilic (pyroninophilic) cells poor in, or free from, glycogen. The larger nodules and carcinomas contained predominantly basophilic cells. The activity of nucleases, especially that of acid DNAse, decreased in small foci which as a rule developed later than the foci of glycogen storage. In most cells of neoplastic nodules and carcinomas the activity of these enzymes disappeared, but it reappeared in necrotic cells. The progressive alterations in the activity of the nucleases seemed to be related to the phenotypic expression of malignancy and could be a sign of a fundamental metabolic change taking place during a relatively late step in the malignant transformation.

Animals↗