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Biomedical subjects

T Takano

Publications and source records attributed to T Takano.

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

Positional specificity of lysosomal acid lipase purified from rabbit liver.

The hydrolysis of tri-, di-, and monooleoylglycerols by highly purified lysosomal acid lipase from rabbit liver (Imanaka, T., et al. (1984) J. Biochem. 96, 1089-1101) was examined. The degradative products were separated by thin layer chromatography on silicic acid impregnated with boric acid. Trioleoylglycerol was hydrolyzed with intermediate accumulation of 1,2(2,3)-dioleoylglycerol and 2-monooleoylglycerol, but no detectable production of the 1,3-isomer. 1,2(2,3)-Dioleoylglycerol was also hydrolyzed with the intermediate accumulation of 2-monooleoylglycerol. The 1(3)-isomer of monooleoylglycerol was hydrolyzed exclusively, with no hydrolysis of the 2-isomer. These results indicate that the enzyme shows preference for 1(3)-ester bonds and that the main lipolytic reaction sequence catalyzed is triacylglycerol---1,2(2,3)-diacylglycerol---2-monoacylglycerol.

Animals↗
PubMed1985

Effect of phospholipids on the hydrolysis of cholesterol oleate liquid crystals by lysosomal acid lipase.

Cholesterol oleate liquid crystals were prepared in vitro as a model of lipid droplets accumulated in the atheromatous aorta. The hydrolysis of cholesterol oleate crystals by lysosomal acid lipase was examined in the presence and absence of various phospholipids. Phosphatidylserine markedly stimulated the hydrolysis of cholesterol oleate liquid crystals (20 times the basal value); it increased the Vmax value about 15 times and decreased the Km value to 1/20 times the basal value. The polar head group and the acyl chains of phosphatidylserine were required for its stimulation of hydrolysis.

Animals↗
PubMed1985

Intracellular respiratory dysfunction and cell injury in short-term anoxia of rabbit renal proximal tubules.

The effects of short-term anoxia and hypoxia were studied in a rabbit proximal renal tubule suspension in order to avoid the hemodynamic consequences of clamp-induced ischemia. The suspension was subjected to anoxia for 10-40 min and the effects on a number of cellular transport and respiratory parameters were monitored. Cellular respiration was measured upon addition of nystatin (Nys) to maximally stimulate Na pump activity. Mitochondrial respiration was measured in the tubules by addition of digitonin and ADP to obtain the state 3 respiratory rate. The release of lactate dehydrogenase (LDH) was measured as an index of plasma membrane damage. The cellular contents of K and Ca were also measured. Results show that 10 and 20 min of anoxia partially inhibited Nys-stimulated and mitochondrial respiration, and partially decreased the K contents, but all these effects were largely reversible after 20 min of reoxygenation. After 40 min of anoxia and 20 min of reoxygenation, all these variables remained irreversibly inhibited: Nys-stimulated respiration by 54%, mitochondrial respiration by 50%, K content by 42%, and LDH release was 40% of total. Ca content decreased slightly during anoxia, but increased up to fourfold during severe hypoxia; the excess Ca was released during the first 10 min of reoxygenation. The degree of respiratory impairment was identical during anoxia or hypoxia, suggesting that Ca accumulation was not associated with the impairment. Decreasing the extracellular Ca to 2.5 microM decreased LDH release significantly during anoxia, suggesting that plasma membrane damage during anoxia may be associated with increased intracellular free Ca. Addition of Mg-adenosine triphosphate during anoxia dramatically improved recovery of all the measured parameters after the anoxic period.

Adenosine Triphosphate↗
PubMed1985

Effects of synthetic analogs and fragments of bovine parathyroid hormone on adenosine 3',5'-monophosphate level, ornithine decarboxylase activity, and glycosaminoglycan synthesis in rabbit costal chondrocytes in culture: structure-activity relations.

Previously, we demonstrated that PTH increases the level of cAMP, the activity of ornithine decarboxylase (ODC; EC 4.1.1.17; which is a rate-limiting enzyme in polyamine biosynthesis), and glycosaminoglycan (GAG) synthesis (which is characteristic of the chondrocyte phenotype) in rabbit costal chondrocytes in culture. These studies suggested that the accumulation of cAMP and the induction of ODC by PTH are good markers of the differentiated phenotype of cultured chondrocytes. In the present study, the biological effects of a series of bovine PTH (bPTH) fragments and analogs on these three parameters of PTH action were examined. bPTH-(1-34), [Nle8,Nle18,Tyr34]bPTH-(1-34) amide and bPTH-(1-27) amide increased cAMP levels, ODC activity, and GAG synthesis in a dose-dependent manner over the concentration range of 10(-9)-10(-5) M. The order of decreasing potency was: bPTH-(1-34), [Nle8,Nle18,Tyr34]bPTH-(1-34) amide, and bPTH-(1-27) amide. On the other hand, [Nle8,Nle18,Tyr34]bPTH-(3-34) amide, bPTH-(5-27) amide, and [Tyr34]bPTH-(20-34) amide failed to increase cAMP levels, ODC activity, or GAG synthesis when present in concentrations up to 10(-5) M. However, [Nle8,Nle18,Tyr34]bPTH-(3-34) amide, bPTH-(5-27) amide, and [Tyr34]bPTH-(20-34) amide inhibited bPTH-(1-34)-stimulated increases in cAMP and ODC activity. These results partially define the principal structural determinants within the PTH molecule required for biological activity and expression of the differentiated phenotype of chondrocytes.

Animals↗
PubMed1985

Ventricular tachycardia associated with acute myocardial infarction--features, therapeutic effect and prognosis.

This study was performed to delineate the precise features and the treatment of ventricular tachycardia (VT) with acute myocardial infarction (AMI). Results indicate: 1) the incidence of VT in 310 AMI patients was 16.1% (50 patients); 2) the higher incidence of ventricular fibrillation and mortalities were observed in VT group compared with non-VT group; 3) the incidence of VT was higher in inferior infarction group (21.0%) than anterior group (13.1%); 4) more frequent VT were seen in patients with more severe heart failure; 5) two peaks of VT occurrence, on the first day and in the 4th week after the onset of AMI, were recognized especially in anterior infarction group; 6) supraventricular arrhythmias were more frequent than ventricular premature beats during one minute preceding VT; 7) the successful termination of VT was achieved in 63.9% of episodes by thump-version, 61.5% by lidocaine, 66.7% by disopyramide and 100% by mexiletine; 8) prophylactic effect on VT by class Ia antiarrhythmic agents seemed stronger than others; 9) IABP was effective to prevent VT in some cases; 10) poor prognosis was determined by frequent and later onset of VT, and combination of severe heart failure.

Aged↗
PubMed1985

Effect of esterastin, an acid lipase inhibitor, on the free and esterified cholesterol contents of cultured aortic smooth muscle cells treated with LDL and cholesterol ester liquid crystals.

The effects of esterastin, an acid lipase inhibitor, on the free and esterified cholesterol contents of cultured smooth muscle cells from pig aorta were examined. The post-nuclear supernatant fraction of the cell homogenate showed maximum acid cholesterol esterase activity at pH 4.5, and 50% of this activity was inhibited by 0.31 microM esterastin. During a 48 h incubation with esterastin, the esterified cholesterol content of the cells increased to about 13 times that of control cells in the presence of low density lipoprotein and to 7 times that of control cells in the presence of cholesterol oleate liquid crystals. The ratio of esterified to free cholesterol also increased to about 5 times the control value in both conditions.

Animals↗
PubMed1985

Subcellular localization of acid lipase in rat liver.

The intracellular localization of acid lipase was examined by several subcellular fractionation techniques. Upon differential centrifugation, acid lipase was detected mainly in the lysosomal fraction. When linear sucrose density gradient centrifugation was used, the mean density of acid lipase was similar to that of lysosomal marker enzymes. After Triton-treatment of rats, however, acid lipase was recovered at a density of 1.10-1.16, which is more than that of tritosomes, when tissues were homogenized with a Potter-Elvehjem homogenizer. But by homogenizing the liver from these rats by pressing it through a stainless steel net, acid lipase was mainly recovered at the same density as that of tritosomes. These results indicate that acid lipase is localized mainly in lysosomes in rat liver.

Animals↗
PubMed1984

High-resolution studies in patients with aniridia-Wilms tumor association, Wilms tumor or related congenital abnormalities.

We attempted to determine whether all cases of AWTA (anirida-Wilms tumor association) or any of the following groups of patients show 11p deletion: cases of Wilms tumor with congenital abnormalities other than aniridia, those without any congenital abnormalities, tumor itself in cases of Wilms tumor without constitutional 11p deletion and cases of aniridia or hemihypertrophy without Wilms tumor. We studied a total of 29 index patients including five cases of AWTA, four cases of Wilms tumor with various congenital abnormalities, 16 cases of Wilms tumor without other abnormalities, three cases of aniridia in one of which Wilms tumor developed later and a case of hemihypertrophy. In all five cases of AWTA and in a case of aniridia who later developed Wilms tumor, 11p deletion involving the p13 band was detected. The mother of the latter also showed an identical 11p deletion. The common segment of deletion was the middle part of the p13. Two possible hypotheses on the mechanism through which Wilms tumor might develop were evaluated, based on the distribution of break points. All other cases, including five with tumor culture, showed a normal karyotype.

Adolescent↗
PubMed1984

Fatal intoxication by 1,2-dichloroethane--a case report.

This is a case report of acute fatal intoxication after accidental exposure to 1,2-dichloroethane in a 51-year-old man. Clinical manifestations, blood chemistry, and autopsy findings are described. High levels of lactate and ammonia in blood had been observed before the elevation of glutamic transaminases, lactic dehydrogenase, and creatine phosphokinase. Ornithine carbamyl transferase and glutamic oxaloacetic transaminase of mitochondrial origin (m-GOT) were remarkably high.

Accidents, Occupational↗
PubMed1984

Comparative light and scanning electron microscopic observations of nasal cavity carcinogenesis in rats treated with 1,4-dinitrosopiperazine.

Epithelial lesions in the nasal cavity of male F344 rats appeared as papillary and nodular hyperplasias progressing to invasive carcinomas during administration of 1,4-dinitrosopepirazine (DNP) at a dose of 0.01% in the drinking water. Observations with specific attention to the cells covering the luminal surface of the mucosa were made by scanning electron microscopy at 10-week intervals. After administration of DNP for 20 and 30 weeks three different types of light microscopically identifiable focal lesions, i.e., papillary hyperplasia, nodular hyperplasia and papilloma, of the epithelium in the nasal cavity were distinguished, and after 40 and 50 weeks areas of squamous cell carcinomas were also observed. In the scanning electron microscope, papillary hyperplasia appeared as a nodular elevation of the surface with a smoother appearance than the surrounding nonnodular areas. Areas of nodular (inverted) hyperplasias had irregularly shaped indentions of the surface. Papillomas appeared as pedunculated projections of the surface. Carcinoma presented as a protrusion of irregular cell masses. The surface cells in the areas of papillary and nodular hyperplasias and of papilloma had numerous short microvilli rather uniform in shape (short-uniform microvilli), unlike the normal epithelium in the nasal cavity, which possesses cilia or olfactory vesicles. The microvilli of carcinoma cells were more irregular in shape and size than those of hyperplastic cells (pleomorphic microvilli).

Animals↗
PubMed1984

Cytoskeleton and differentiation: effects of cytochalasin B and colchicine on expression of the differentiated phenotype of rabbit costal chondrocytes in culture.

Cytochalasin B changed the shape of cultured rabbit costal chondrocytes from polygonal to nearly spherical and stimulated glycosaminoglycan synthesis, which is a differentiated phenotype of chondrocytes, whereas colchicine changed them from polygonal to flattened and inhibited glycosaminoglycan synthesis. These morphological changes occurred parallel with the changes in glycosaminoglycan synthesis. Induction of ornithine decarboxylase by parathyroid hormone, which is a good marker of differentiated chondrocytes, was markedly potentiated in the spherical cells which had been pretreated with cytochalasin B, whereas pretreatment with colchicine inhibited the induction of the enzyme. Both cytochalasin B and colchicine inhibited DNA synthesis. The inhibitions were observed after the appearance of changes in the morphology of the cells and glycosaminoglycan synthesis. These findings suggest that intactness of microtubules and disruption of microfilaments are involved in regulating the expression of the differentiated phenotype of chondrocytes in culture.

Animals↗
PubMed1984

Combined effect of nitrogen dioxide and cold stress on the activity of the hepatic cytochrome P-450 system in rats.

The combined effects of nitrogen dioxide (NO2) and cold stress were assessed on the cytochrome P-450 system by measuring microsomal protein content, cytochrome P-450 content, aminopyrine N-demethylase activity, and aniline hydroxylase activity in the liver of male Wistar rats exposed to 4 ppm NO2 and/or cold environment (4 degrees C) for 24 h, 14 days, and 30 days. Exposure to cold alone changed the activity of the cytochrome P-450 system during the exposure up to 30 days, and exposure to NO2 alone also influenced it after 14 days and 30 days of exposure. Interactions were observed in the effect on the cytochrome P-450 system when rats were exposed to NO2 and cold simultaneously. There was a tendency that NO2 suppressed the increases in activities of the cytochrome P-450 system caused by cold of 24-h and 30-day exposure.

Aminopyrine N-Demethylase↗
PubMed1984

Proton translocating ATPase in lysosomal membrane ghosts. Evidence that alkaline Mg2+-ATPase acts as a proton pump.

Membrane ghosts were prepared from purified lysosomes (tritosomes) of rat liver by hypo-osmotic treatment. Mg2+-ATP-driven acidification was observed in the membrane ghosts using acridine orange as a fluorescent probe of the transmembrane pH gradient (delta pH). Its properties were the same as those of intact lysosomes reported previously (Ohkuma, S., Moriyama, Y., & Takano, T. (1982) Proc. Natl. Acad. Sci. U.S. 79, 2758-2762; Moriyama, Y., Takano, T., & Ohkuma, S. (1982) J. Biochem. 92, 1333-1336). The H+-pump was found to be electrogenic with use of bis(3-phenyl-5-oxoisoxasol-4-yl)pentamethine oxonol as a fluorescent membrane potential probe. Alkaline Mg2+-ATPase activity was also identified on the membranes. It showed a pH maximum of pH 8.0-8.5, a Km value for ATP of 0.36 mM and a Vmax of 0.41 units/mg protein at 30 degrees C. Its activity was inhibited by dicyclohexylcarbodiimide, tri-n-butyltin, azide and ADP, but not by ouabain or vanadate. It differed from mitochondrial F1F0-ATPase in sensitivities to N-ethylmaleimide, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, quercetin, and oligomycin. Since this alkaline Mg2+-ATPase activity is very similar to the H+-pump activity in its requirement for divalent cations, substrate specificity and sensitivities to various chemicals, it may act as a proton translocase (H+-pump). Possible mechanisms of action of some chemicals, such as 4-acetamide-4'-isothiocyanatostilbene-2,2'-disulfonic acid, that inhibited the H+-pump but not the alkaline Mg2+-ATPase, are discussed.

4-Chloro-7-nitrobenzofurazan↗