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Biomedical subjects

T Imamura

Publications and source records attributed to T Imamura.

At least 577 records · Page 32Linked to original sources
PubMed1985

Inhibitory effect of various organophosphorus esters on rat liver malathion carboxylesterase in vitro: role of mixed-function oxidases.

6 Structurally related trialkyl phosphorothioates were assessed for their inhibitory effects on rat liver malathion carboxylesterase in vitro. IC50 values indicate that all these compounds, except compound III, a phosphorodithioate, inhibited the activity of the enzyme progressively with increasing incubation time of the compounds with the enzyme preparation. Compounds with an ethyl substitution were more potent than the corresponding methyl-substituted inhibitors. There was cytochrome P-450-mediated oxidative deactivation of all compounds tested, this was especially profound with inhibitors containing an ethyl thiolate moiety.

Animals↗
PubMed1985

Malignant fibrous histiocytoma of maxilla following radiotherapy for bilateral retinoblastoma.

A 20-year-old man developed a malignant fibrous histiocytoma in the right maxilla 19 years after irradiation for bilateral retinoblastoma. The incidence of second tumours in patients who survived bilateral retinoblastoma treated with radiation was 8.5 per cent. Malignant fibrous histiocytomas which arise in a site of prior radiation are fatal. The present case is presumed to have the autosomal dominant retinoblastoma gene, not associated with deletion of the q 14 band of chromosome 13. The patient succumbed to the second tumour.

Adult↗
PubMed1985

Development of tolerance to a pneumotoxic impurity of malathion.

O,O,S-Trimethyl phosphorothioate (OOS-Me) is a pneumotoxic impurity present in various organophosphorus insecticides. OOS-Me produces morphological alteration of bronchiolar epithelial Clara cells accompanied by an increase in pulmonary lavage lactate dehydrogenase activity and severe weight loss in rats. Tolerance to the pneumotoxicity of OOS-Me was induced rapidly by oral pretreatments with small doses of OOS-Me itself. O,O-Dimethyl-S-ethyl phosphorothioate (OOS-Et), a pneumotoxic trialkyl phosphorothioate that is closely related in structure to OOS-Me, also produced a tolerance by oral pretreatment with small doses of OOS-Et itself. Pretreatment of rats with OOS-Me produced tolerance to OOS-Et, pretreatment did not produce tolerance to OOS-Me. Pretreatment of rats with tolerance-inducing doses of OOS-Me or OOS-Et had no effect on pulmonary or hepatic monooxygenase activities. Malathion and phenthoate carboxylesterases in pulmonary and hepatic microsomes were inhibited by these pretreatments. Activity of superoxide dismutase in lung or glutathione content in lung or liver was not affected by these pretreatments. Although the mechanism(s) remains unknown, the present study demonstrated the tolerance development to the chemical-induced pneumotoxicity.

Administration, Oral↗
PubMed1985

Digitalis-induced augmentation of cardiopulmonary baroreflex control of forearm vascular resistance.

We sought to determine whether digitalis augments cardiopulmonary baroreflex control of forearm vascular resistance in normal young men. Cardiopulmonary baroreceptor input was reduced with lower body negative pressure (LBNP) at 10 and 20 mm Hg, which decreased central venous pressure but did not alter blood pressure or heart rate. Decreases in forearm blood flow and increases in forearm vascular resistance with LBNP were greater after administration of lanatoside C (Cedilanid) than before, and the slope of the regression line relating changes in central venous pressure and those in forearm vascular resistance was steeper after lanatoside C. Vasoconstrictor responses to the cold pressor test did not differ before and after lanatoside C, which suggested that augmented responses to LBNP after the drug were not caused by a generalized change in reflex control. These results suggest that lanatoside C augments the tonic inhibitory influence of cardiopulmonary baroreceptors in normal men.

Adult↗
PubMed1985

Hemoglobin Rahere, a human hemoglobin variant with amino acid substitution at the 2,3-diphosphoglycerate binding site. Functional consequences of the alteration and effects of bezafibrate on the oxygen bindings.

We encountered an abnormal hemoglobin (Rahere), with a threonine residue replacing the beta 82 (EF6) lysine residue at the binding site of 2,3-diphosphoglycerate, which was responsible for overt erythrocytosis in two individuals of a Japanese family. Hemoglobin Rahere shows a lower oxygen affinity on the binding of 2,3-diphosphoglycerate or chloride ions than hemoglobin A. Although a decrease in the positive charge density at the binding sites of 2,3-diphosphoglycerate in hemoglobin Rahere apparently shifts the allosteric equilibrium toward the low affinity state, it greatly diminishes the cofactor effects by anions. The oxygen affinity of the patient's erythrocytes is substantially lowered by the presence of bezafibrate, which combines with sites different from those of 2,3-diphosphoglycerate in either hemoglobin Rahere or hemoglobin A.

2,3-Diphosphoglycerate↗
PubMed1985

Genetic and environmental factors in the development of Behcet's disease.

Analysis of HLA antigens and case control study were performed in 50 patients with Behcet's disease. Frequency of HLA-Bw51 was significantly increased in the patients (52.0%) as compared to that in the control subjects (16.0%). In case control study, the incidence of tonsillitis, and use of public bath and a privy were more frequently seen in the patients than in the controls. The patients were frequently exposed to agricultural chemicals before onset of the disease. Daily ingestion of vegetable salad and milk was less frequent in the patients than in the controls. Heterogeneity of Behcet's disease and results of multivariate analysis for selected variables were discussed.

Adult↗
PubMed1985

Hemoglobin A2 Honai (alpha 2 delta 2(90)(F6)Glu----Val): a new delta chain variant.

A new slow-moving variant of hemoglobin(Hb) A2, designated as Hb A2 Honai, was found to have an amino acid substitution of valine for glutamic acid at position 90(F6) in the delta chain. Hb A2 Honai comprised 0.84% of total hemoglobin. Hb A2 and Hb A were estimated to be 1.30% and 97.85%, respectively. Hb A2 Honai was observed in 4 members of a family in 3 generations. No hematologic abnormalities were associated with Hb A2 Honai.

Aged↗
PubMed1984

Lectin-like molecules on the murine macrophage cell surface.

Lectin-like molecules on the surface of murine peritoneal exudate macrophages induced by thioglycolate or an anti-tumor streptococcal preparation, OK-432, were investigated and isolated. Furthermore, their sugar-binding specificities and their role in macrophage-mediated tumor cytotoxicity were examined. A neoglycoprotein, D-galactose (Gal)-bovine serum albumin, bound to these murine peritoneal macrophages. This binding of Gal-bovine serum albumin was inhibited by D-galactose, and by complex-type oligosaccharides (unit B) and high mannose-type oligosaccharides (unit A) prepared from porcine thyroglobulin. When thioglycolate-elicited macrophages were activated by lipopolysaccharide and/or the culture supernatant of concanavalin A-activated mouse spleen cells, they became tumoricidal and the number of the lectin-like molecules on the macrophage surface was found to increase. Since the binding and cytotoxic activities of these tumoricidal macrophages toward tumor cells were partially inhibited by D-galactose, the D-galactose-binding lectin-like molecules on the surface of tumoricidal macrophages might play an important role in macrophage-mediated cytotoxicity. These lectin-like molecules were then isolated from solubilized murine peritoneal exudate cells labeled with pyridoxal 5'-phosphate and sodium [3H]borohydride by affinity chromatography on columns of asialo unit B oligosaccharide-Sepharose 4B and/or beta-D-galactose-Bio-Gel P-100. The proteins bound to the asialo unit B oligosaccharide-Sepharose 4B column and eluted specifically were found to have approximate molecular weights of 79 000 and 18 000, and the protein bound to and eluted from the beta-D-galactose-Bio-Gel P-100 column had an approximate molecular weight of 77 000. These isolated proteins bound to the surface of glutaraldehyde-fixed tumor cells, and their binding was inhibited by D-galactose and also by D-mannose. Since most of the 77 kDa protein bound to the asialo unit B oligosaccharide-Sepharose 4B, this protein was assumed to be identical with the 79 kDa protein. These results suggest that the lectin-like molecules on murine macrophages have wide specificity and that one lectin-like molecule can bind both D-galactose and D-mannose.

Animals↗