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Biomedical subjects

Y Takamura

Publications and source records attributed to Y Takamura.

At least 109 records · Page 6Linked to original sources
PubMed1986

Arginine sensors in the hepato-portal system and their reflex effects on pancreatic efferents in the rat.

To investigate the possible existence of arginine sensors in the liver and their reflex effects, afferent discharges from the hepatic branch of the vagus nerve and efferent discharges from the pancreatic branches of the splanchnic and vagus nerves were recorded. Intraportal injection of arginine increased afferent discharge rate of the hepatic branch of the vagus nerve, slightly depressed the efferent discharge rate of the pancreatic vagal branch, and increased the efferent discharge rate of the pancreatic splanchnic branch. The results suggest the existence of arginine sensors in the hepato-portal system that exert reflex regulation of the pancreatic neuroendocrine system.

Animals↗
PubMed1986

Enhancement of insulin and glucagon secretion by arginine after hepatic vagotomy.

The hepatic vagus nerve consists of mostly afferent fibers in the rat, and is a major afferent pathway between the liver and the medulla. The present study was carried out to examine the role of the hepatic branch of the vagus nerve in secretion of insulin and glucagon after intraperitoneal injection of arginine (1 g/kg body wt.) in rats. Measurements were made one week after section of this branch. Intraperitoneal arginine enhanced both plasma insulin and glucagon concentrations; more in hepatic-vagotomized than in sham-vagotomized rats. The results suggest that inhibition of the secretion of insulin and glucagon after arginine stimulation is mediated by the hepatic branch of the vagus nerve. The existence of 'sensors' in the liver for arginine, or its derivatives, is proposed as an explanation for the inhibition of the secretion of insulin and glucagon by the hepatic vagus nerve.

Animals↗
PubMed1986

[Effect of mazindol on glucose absorption in everted rat small intestine].

Effect of an anorexiant, mazindol, on glucose absorption was investigated. Ten weeks-old female Sprague-Dawley rats were divided into mazindol treated (fed on powder diet containing 100 mg/kg of mazindol) and control groups. Four weeks later, experiments of continuous observation of glucose absorption and glucose transport were performed in each group using the everted sac method. During 180 min of continuous observation of glucose absorption, significantly lowered glucose concentrations of the serosal medium were observed in the mazindol treated group at oral and caudal ends of the upper, caudal end of the middle, and caudal ends of the lower small intestine, whereas no significant differences in glucose concentrations of the mucosal medium were observed between the two groups. After 60 min incubation for monitoring the glucose transport, significantly decreased glucose concentrations of serosal medium were observed in mazindol treated group at oral and caudal ends of the upper, caudal ends of the middle and caudal ends of the lower small intestine, whereas no significant differences in glucose concentrations of mucosal medium were observed. The results suggested that there is little effect on glucose absorption, but the metabolism of glucose or the remaining glucose in the small intestinal wall is increased by mazindol treatment.

Animals↗
PubMed1985

Malonyl-CoA: acetyl-CoA cycling. A new micromethod for determination of acyl-CoAs with malonate decarboxylase.

A new micromethod for determination of acetyl-CoA and malonyl-CoA using malonate decarboxylase is described. This enzyme catalyzes decarboxylation of malonate in a cyclic manner and produces acetate in proportion to the amount of a given acyl-CoA, such as acetyl-CoA, malonyl-CoA or propionyl-CoA. The acetate generated is converted to acetylphosphate by acetate kinase (EC 2.7.2.1) added at the same time and is determined spectrophotometrically as acetohydroxamate. The sensitivity of this method is high enough to detect 10(-12) mol of acetyl-CoA or malonyl-CoA. The simplicity of the method allows more than 30 samples to be analyzed at the same time without any prior extraction step. Although this method does not distinguish between acetyl-CoA and malonyl-CoA, malonyl-CoA alone can be measured by elimination of acetyl-CoA with citrate synthetase (EC 4.1.3.7).

Acetate Kinase↗
PubMed1985

Increased triglyceride secretion rate and hyperinsulinaemia in ventromedial hypothalamic lesioned rats in vivo.

The present study aimed to measure triglyceride secretion rate (TGSR) into the circulation in ventromedial hypothalamic (VMH) lesioned rats. Average gain of body weight in VMH lesioned rats was 72 +/- 6 g (mean +/- SE, n = 9) in a week; significantly greater than that in controls (6 +/- 2, n = 8, P less than 0.001). TGSR was determined under hexobarbital anaesthesia in fasted rats by measuring the increase in plasma concentration after the triglyceride removal mechanism was blocked by injecting Triton WR-1339. TGSR in VMH lesioned rats was 500 +/- 37 mg/dl of plasma/h; markedly higher than that in controls (239 +/- 12, P less than 0.001). Serum insulin concentration in VMH lesioned rats was 2.26 +/- 0.32 ng/ml; significantly higher than that in controls (0.83 +/- 0.08, P less than 0.001). There was a positive correlation between serum insulin concentration and TGSR in VMH lesioned rats (r = 0.709, P less than 0.05). The increased secretion rate of triglyceride in VMH lesioned rats is discussed in connection with the development of obesity in these rats.

Animals↗
PubMed1984

Effects of ventromedial hypothalamic lesions on circadian rhythms in serum insulin, glucose, triglyceride and food intake in rats.

The effects of ventromedial hypothalamic (VMH) lesions on the circadian periodicity of serum insulin, glucose, triglyceride and food intake were studied in rats. The rhythms of serum insulin, glucose and triglyceride did not persist in VMH lesioned rats. The glucose level during the light period was reduced. The triglyceride and insulin levels were elevated. The VMH lesions markedly increased food intake during the later half part of the light cycle but kept it significantly less during the first half part. Thus, the VMH lesions abolished the circadian rhythmicity of serum insulin, glucose and triglyceride and attenuated the rhythmicity of eating through increase in daytime consumption.

Animals↗
PubMed1984

Enhancement of glutathione S-transferase activity in rat liver by repeated administration of propylthiouracil.

Treatment of rats with propylthiouracil for one to two weeks caused an increase in glutathione S-transferase (GST) activity of the liver cytosol, but not of the particulate fraction. Increased GST activity was reversed two weeks after discontinuing PTU administration. Activation of the enzyme was inversely proportional to the decrease in leukocytes. Repeated administration of PTU increased the Vmax of the enzyme without affecting the Km value for the substrate 1-chloro-2,4-dinitrobenzene, whereas both the Km and Vmax for glutathione (GSH) were increased by PTU treatment. GSH content and GSH peroxidase activity were not affected by PTU, but this resulted in an increase in glucose 6-phosphate dehydrogenase activity. PTU treatment caused increase in GST activity using 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, p-nitrobenzyl chloride, and benzalacetone as substrates; enzyme activity towards chlorodinitrobenzene was the highest.

Animals↗
PubMed1982

Effect of paromomycin sulfate on endotoxemia in patients with cirrhosis.

We evaluated, in a randomized double-blind trial, the efficacy of oral paromomycin sulfate administration in the prevention of endotoxemia in 24 cirrhotic patients with endotoxemia. Renal function was evaluated by glomerular-filtration rate and renal plasma flow at the beginning and at the end of the study period. After the administration of paromomycin sulfate, 2 g/day for 4 weeks, endotoxemia disappeared in 10 out of 13 (76.9%) cirrhotic patients with endotoxemia, whereas it became negative in only 3 of the 11 (27.3%) treated with placebo, the difference being significant (P less than 0.05). With regard to correlation of endotoxemia with renal impairment, endogenous creatinine clearance and p-aminohippurate clearance were significantly improved (P less than 0.02) in those patients whose endotoxemia disappeared on paromomycin sulfate administration. We did not find significant improvement, however, neither in liver function or in blood coagulation tests in the same patients. Paromomycin sulfate seems to be effective in the prevention of endotoxemia and the associated renal impairment in cirrhosis in man.

Acute Kidney Injury↗