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Biomedical subjects

N Hosoya

Publications and source records attributed to N Hosoya.

At least 91 records · Page 5Linked to original sources
PubMed1982

Demonstration of sucrase-isomaltase complex in chick intestine.

It was investigated whether sucrase and isomaltase form an enzyme-enzyme complex in chick intestine or not, and some properties of the disaccharidases were compared with those of other species. 1) Chick intestinal sucrase and isomaltase were shown to exist in the form of an enzyme-enzyme complex from the results of polyacrylamide disc gel electrophoresis, DEAE Sephadex A-25 ion exchange column chromatography and citraconylation, although the chick intestinal sucrase and isomaltase were not retained on a Sephadex G-200 column. 2) The molecular weights of sucrase-isomaltase complex, maltase I, maltase II, maltase III and isomaltase dissociated from sucrase-isomaltase complex were estimated to be 250,000, 250,000, 160,000, 225,000 and 80,000, respectively, by polyacrylamide disc gel electrophoresis. 3) The optimum pH for all the enzymes was 6.0. 4) Km values of sucrase, isomaltase, maltase I and maltase III were 10.0, 3.5, 1.0 and 4.6 mM, respectively. Vmax values for sucrase, isomaltase, maltase I and maltase III were 217.4, 281.4, 147.1 and 454.5 mumol substrate hydrolyzed/mg protein/hr, respectively.

Animals↗
PubMed1982

Property and physiological role of biliary secretory IgA in rats.

Secretory IgA (sIgA) and monomeric IgA (mIgA) were purified from normal rat bile, and their role in the gastrointestinal tract was investigated. Biliary sIgA has a molecular weight of approximately 400,000 daltons and a sedimentation constant of 11.7S. Thus, sIgA obtained from rat bile had physicochemical properties similar to those reported for sIgA in other secretions, and probably consists of L-chains, alpha-chains and secretory component. After in vitro incubation with trypsin or intestinal fluid, sIgA remained intact, whereas mIgA was hydrolyzed. Rats challenged repeatedly with dinitrophenylated bovine serum albumin (DNP-BSA) had specific IgA antibody against DNP in the bile and feces as measured by a radioimmunoassay using [3H]-DNP-lysine. Our results demonstrate a possibility that biliary sIgA, not mIgA, has an important role which inhibits the absorption of foreign antigen from intestine.

Animals↗
PubMed1982

[Effects of bromocriptine and dopamine on pituitary hormone secretion in women].

The present study was designed to examine whether a dopamine agonist, bromocriptine (Brc) exerts similar effects as dopamine (DA) on the pituitary hormones secretion and also to investigate the interaction of these dopaminergic agents and a dopamine receptor antagonist, metoclopramide (MCP) on the DA receptors in the hypothalamic-pituitary axis. Thirty normal cycling women in the midfollicular phase volunteered for this study. Following the administration of Brc (2.5mg, orally) to 13 subjects, a partially significant fall in LH levels, but not in FSH levels, during 4h was observed. DA, infused at a rate of 5 micrograms/kg/min for 4h, induced a significant fall in LH levels between 1 and 4h, but in FSH levels only at 2.5h after the start of infusion in 9 subjects. The amplitude of the spontaneous pulsations of LH secretion which was observed in 8 control subjects, was diminished by DA, while the amplitude seemed to be augmented by Brc. The administration of MCP (10mg, i.v.) to all subjects at 3h during the 4h experimental period caused no observable change in LH and FSH levels. A significant and progressive decline in PRL levels was observed in both Brc-and DA-treated groups of subjects, and this PRL-lowering effect was markedly counteracted by MCP administration in DA-treated group, but not in Brc-treated group. Brc induced a widely varying but significant rise in GH levels, with which MCP did not appear to interfere, whereas DA failed to cause any significant changes in GH levels. These data suggest that Brc, in contrast with DA, seems to be able to increase the pulse amplitude, but not the basal level, of LH and to stimulate GH secretion. Brc is also regarded to be a potent and unique PRL inhibitor, because its PRL-lowering effect cannot be easily antagonized by MCP.

Adult↗
PubMed1981

A new aspect on the mechanism of intestinal cholesterol absorption in rat.

In order to study the mechanism of intestinal cholesterol absorption, the relationship between the amount of cholesterol administered and the rate of absorption was investigated by the dual isotope plasma ratio method in vivo and the ligated-loop method in situ. The energy requirement of cholesterol absorption was also observed by means of the ligated-loop method. The results obtained are summarized below. 1) Tri-phase absorption was observed by the dual isotope plasma ratio method. When less than 300 microgram of cholesterol was administered, absorption increased linearly, with the coefficient of absorption being more than 80%. When the amount administered was between 300 and 500 microgram, the absorption was constant. With the administration of more than 500 microgram, absorption increased linearly, but the coefficient of absorption decreased to approximately 55%. 2) With the ligated-loop method, a second saturation profile was obtained when between 250 and 400 microgram of cholesterol was administered to a segment. When 50 to 250 microgram of cholesterol were administered, absorption increased in proportion to the increase in cholesterol dosage. 3) The mucosal uptake of cholesterol decreased to 40-60% of the control with the addition of metabolic inhibitors such as NaN3, KCN, 2,4-DNP and ouabain, whereas the uptake of palmitate showed no significant decrease. In addition, the uptake of cholesterol decreased remarkably to 25% of the control with the lowering of body temperature from 37 degrees C to 27 C. These results suggest the existence of an active transport system which has a limited capacity for cholesterol absorption and which requires energy for its operation in the physiological state.

Animals↗
PubMed1981

Nitrogen balance and hepatic gluconeogenesis in rats fed on diets containing various proportions of carbohydrate and fat.

This study was conducted to investigate the effects of various proportions of dietary carbohydrate and fat in diet on protein and carbohydrate metabolism. The growth rate, nitrogen balance, urinary and serum urea levels, and the activities of key ureogenic and gluconeogenic enzymes in the livers were examined in the weanling and growing rats. The rats were raised on a 20% casein diet containing various proportions of carbohydrate and fat, viz. 30% and 50%, 50% and 30%, 60% and 20% or 70% and 10% as calorie percent, respectively, for 10 days. For both weanling and growing rats, the growth rate was unaffected by the alteration in the proportions of carbohydrate and fat in the diets. However, in the rats fed on the 30% carbohydrate-50% fat diet, the urinary excretion of nitrogen and urea were reduced in both groups and these findings were reflected in the reduced serum urea level. Arginase activity decreased. In contrast, glucose-6-phosphatase activity was enhanced in the animals of the 30% carbohydrate-50% fat diet group as compared to the other groups. These results suggest that a low carbohydrate-high fat diet causes the reduction of urea formation and the enhancement of glucose formation at a fixed level of protein in the diets in weanling as well as in growing rats.

Aging↗
PubMed1980

Effect of 1,25-dihydroxycholecalciferol on the duodenal villi and alkaline phosphatase in the developing chick embryo.

Administration of 1,25-(OH)2D3 to developing 14-day chick embryo gave precocious induction of alkaline phosphatase in 20-day chick embryonic duodenum. 1,25-(OH)-2D3-induced alkaline phosphase involved in changes in Km and Vmax values. Furthermore, polyacrylamide gel disc electrophoresis of n-butanol-solubilized alkaline phosphatase from control and 1,25-(OH)2D3-treated chick embryonic duodenum revealed that 1,25-(OH)2D3 involved the transformation of neuraminidase-resistant fast migrating form to the neuraminidase-sensitive faster migrating one. Scanning electron microscopic data showed that the injection of 1,25-(OH)2D3 stimulated the elongation of duodenal microvilli, although there was no effect on the duodenal absorptive epithelial cell height.

Alkaline Phosphatase↗
PubMed1980

Inhibition of beta-sitosterol on intestinal cholesterol absorption in rat using in vivo dual isotope ratio method.

The inhibitory effects of beta-sitosterol on intestinal cholesterol absorption were studied by means of a dual isotope plasma ratio method (in vivo), which is a new technique for the measurement of cholesterol absorption, as well as a ligated-loop method (in situ). The results obtained were as follows: 1. The absorption of beta-sitosterol itself was significantly less than cholesterol. Cholesterol was selectively absorbed from rat intestine. 2. When 100 to 1,000 microgram of beta-sitosterol were added to the dose solution containing 10 microgram of cholesterol, cholesterol absorption by the in vivo experiment decreased with the increae of additional beta-sitosterol. 3. A similar inhibitory effect of beta-sitosterol was observed by the in situ ligated-loop method. These results suggest that beta-sitosterol actually inhibits cholesterol absorption in the physiological state of an animal.

Animals↗
PubMed1980

Purification and characterization of calcium-binding protein containing gamma-carboxyglutamic acid from rat bone.

A gamma-carboxyglutamic acid (Gla)-containing protein was purified from rat femur cortical bone. The presence of 4 Gla residues in the rat protein was shown by amino acid analysis on alkaline and acid hydrolysates. The protein was extracted from rat cortical bone with 0.5 M EDTA (pH 7.6) and purified from the EDTA extracts by gel filtration on Sephadex G-100 and ion-exchange chromatography on DEAE-Sephadex A-25. The protein has a molecular weight of about 6,000 on the basis of amino acid composition. The protein had 56 amino acid residues containing significant amounts of Asp, Glu, and Gla (acidic amino acids). The protein showed calcium-binding activity with Kd = 0.2 mM and calcium-dependent electrophoretic mobility.

1-Carboxyglutamic Acid↗
PubMed1980

Effect of food restriction on intestinal disaccharidases in streptozotocin-induced diabetes of rat.

The effect of food restriction on the intestinal weight and membrane digestive enzyme activities was observed in rats with diabetes induced by streptozotocin. The specific activities of disaccharidases of food non-restricted diabetic rats were not changed, but total activities were significantly increased due to the increase of intestinal mucosal weight. Restriction of food intake did not increase intestinal mucosal weight, but significantly increased the specific and total activities of disaccharidases in parallel with the increase of sucrase-isomaltase content. On the other hand, experimental diabetes did not influence the activity of alkaline phosphatase and leucine aminopeptidase except for specific and total activities of alkaline phosphatase in food non-restricted rats.

Alkaline Phosphatase↗