PubMed Health⌕ Search

Biomedical subjects

Y Oshiro

Publications and source records attributed to Y Oshiro.

80 records · Page 5Linked to original sources
PubMedDate not supplied

Genetic toxicology studies with a tumor promoter.

A diuretic antihypertensive agent, SC-33643 (8-[2-ethoxyethyl]-7-phenyl-[1,2,4]triazolo[4,3-c]pyrimidine-5- amine, also known as bemitradine), was tested in the Ames test, in the mouse lymphoma TK +/- mutation assay, in the Chinese hamster ovary cell hypoxanthine guanine phosphoribosyl transferase (CHO/HGPRT) mutation test and in the CHO chromosome aberration assay with and without metabolic activation. Additionally, the compound was tested in the rat primary hepatocyte unscheduled DNA synthesis (UDS) assay and in the mouse bone marrow micronucleus assay. The results were uniformly negative. Contrary to expectations based on the results of the battery of genetic toxicology tests, the compound produced liver, thyroid and mammary tumors in the rat (reported separately). Subsequently, SC-36741 (5-amino-7-phenyl-[1,2,4]triazolo-[1,5-c] pyrimidine-8-ethanol, also known as desethylbemitradine), a major metabolite of SC-33643, was tested in the Ames test, in the CHO/HGPRT mutation test and in the CHO chromosome aberration assay with and without metabolic activation, and was also tested in the rat primary hepatocyte/UDS assay and in the mouse bone marrow micronucleus assay. This metabolite also produced negative results in these tests. Therefore, SC-33643 is a non-genotoxic carcinogen producing tumors in rats without altering DNA or chromosomes.

Animals↗
PubMedDate not supplied

An in vitro system to screen for diarrheagenic chemicals.

We examined an in vitro system to screen for diarrheagenic chemicals using an established intestinal cell line (T84 human colonic carcinoma). The cells were grown on Millicell-PCF (polycarbonate membrane) wells. The cells were seeded at approximately 5 x 10(6) cells/30mm well and incubated for 9-11 days in a 5% CO2 incubator saturated with water at 37 degrees C. The culture medium was a 1:1 mixture of Ham's F12 and Dulbecco's MEM with 5% fetal bovine serum and 25 micrograms/ml gentamicin sulfate. The well containing cells was removed from the incubator and mounted in a modified Ussing chamber for measurement of short-circuit current (ISC). Chemical-induced increases in ISC are usually indicative of electrogenic epithelial Cl- secretion, which is associated with diarrheagenic effects in animals and humans. T84 cells grown on Millicell-PCF membrane responded with an increase in ISC after basolateral addition of the cholinergic (muscarinic) agonist carbachol, prostaglandin E2, 16,16-dimethylprostaglandin E2, and forskolin, while non-diarrheagenic prostaglandin D2 did not affect ISC. Based on our results, this in vitro system has the potential to be adapted as a rapid screen for detecting diarrheagenic chemicals.

Carbachol↗
PubMedDate not supplied

Exploration of the transformation potential of a unique male rat protein alpha2u-globulin using hamster embryonic cells.

Several environmentally and socially important chemicals such as d-limonene and unleaded gasoline have been demonstrated to induce alpha2u-globulin (alpha 2u) nephropathy in male rats. Substantial progress has been made in characterizing the biological effects of these chemicals on the kidney and in further defining prerequisite events in the pathogenesis of this syndrome. The alpha 2u increase in the kidney is hypothesized to be the proximal event in the toxicologic and tumorigenic sequelae associated with administration of these xenobiotics over the male rat's lifetime rather than a direct effect of the administered chemical. The administered chemical appears to simply mediate the increase in alpha 2u concentration in the kidney. To further investigate the properties of alpha 2u, this protein was tested in the pH 6.7 Syrian hamster embryo (SHE) cell transformation assay. The alpha 2u caused morphological transformation in these cells, whereas another protein, bovine serum albumin, did not induce transformation at equimolar concentrations, suggesting a protein-specific phenomenon. Neither d-limonene nor trimethylpentane (a causal component in unleaded gasoline) induced SHE cell transformation. These results support the hypothesis that alpha 2u increase in proximal convoluted tubules may directly cause renal tumorigenesis in male rats. The SHE cell transformation assay may be a useful tool for mechanistic studies of this syndrome.

Alpha-Globulins↗
PubMedDate not supplied

Pleomorphic leiomyosarcoma of the soft parts: a reassessment by histology and immunohistochemistry of pleomorphic soft tissue sarcomas.

Histologically it is often difficult to differentiate malignant fibrous histiocytoma (MFH) from leiomyosarcoma. Sixty-three cases formerly diagnosed as pleomorphic soft tissue sarcomas were examined by immunohistochemistry. We identified three different types according to its positivity for the myogenic markers: A) positive cells with a fascicular pattern, 13 cases (26%); B) a small number of scattered positive cells, 29 cases (57%); C) negative for markers, 9 cases (17%). We reassessed 51 MFHs as follows: A type as pleomorphic leiomyosarcoma, B+C types as MFH. Pleomorphic leiomyosarcomas were also positive for collagen type IV around the compactly arranged individual tumor cells. An imunohistochemical analysis and detection of fascicular structures are thus considered to be necessary in order to distinguish between leiomyosarcoma and MFH.

Adult↗