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Biomedical subjects

N Hosoya

Publications and source records attributed to N Hosoya.

At least 55 records · Page 3Linked to original sources
PubMed1991

Metabolic fate of ingested [14C]-maltitol in man.

Six healthy male subjects were given a single oral dose of 0.4 g of maltitol per kg body weight containing [U-14C]-maltitol (50 microCi) and their breath, urine, feces and blood were collected at appropriate intervals for 48 h to measure the recovery of administered radioactivity. Further, to measure breath hydrogen, 15 healthy male subjects ingested 30 g of maltitol and samples of their breath were collected for a 10-h period. The expired 14CO2 showed a wide peak about 3 h after ingestion and 56% of the administered radioactivity was recovered in 48 h. An additional 0.2% of administered radioactivity was recovered as expired 14CH4, 2.6% in urine and 14.3% in feces, respectively. The obvious increase of breath hydrogen was detected at 1 h after maltitol ingestion and then a big peak at 3.5 h, whereas maltose ingestion did not increase breath hydrogen. Both excretion profiles of breath 14CO2 and hydrogen coincided well. These results demonstrate that a greater part of ingested maltitol is fermented by intestinal microbes than is hydrolyzed by digestive enzymes. Although maltitol is catabolized to carbon dioxide via intestinal microbes, the available energy is much lower than that of digestible sugars such as sucrose.

Adult↗
PubMed1989

Utilization and excretion of a new sweetener, fructooligosaccharide (Neosugar), in rats.

In order to study the digestibility of the fructooligosaccharide "Neosugar," [U-14C]Neosugar or [U-14C]sucrose was orally administered to germfree, conventional and antibiotic-treated rats and the radioactivities of expired 14CO2, urine and feces were determined 24 h later. More than 50% of the Neosugar was expired as CO2 in conventional rats. This was the same as for sucrose, but the time course was delayed by about 2 h. In germfree rats, no 14CO2 was released for the first 8 h, and 14CO2 released after 8 h probably reflected bacterial colonization of the gut. The radioactivity of the urine was about 3-4% in all groups, but that of the feces from germfree rats was about eight times higher than the level in conventional rats. When [U-14C]Neosugar was anaerobically incubated with the cecal contents of conventional rats, more than 10% of the added Neosugar was metabolized to CO2, about 66% to volatile fatty acids and about 7% to microbes. More than 58% of 1-14C-volatile fatty acids such as acetic acid, propionic acid or butyric acid injected directly into the cecum of conventional rats was excreted as CO2 within 24 h. These results indicate that Neosugar given orally to rats is metabolized mainly to volatile fatty acids and CO2 by intestinal microorganisms, and the volatile fatty acids produced are absorbed and further converted to CO2 in the body. Thus, the data indicate that Neosugar is partially utilized as an energy source.

Acetates↗
PubMed1988

[Small intestinal alkaline phosphatase activity and changes induced by cysteamine administration in fecal excretions of male Wistar rats].

Alkaline phosphatase (ALP) activity in fecal excretions was measured in male Wistar rats. Total daily ALP activity in fecal extracts was 133.1 +/- 21.2 mumoles/min per rat weighing approximately 150 g. We found that 63.7% of the fecal ALP activity was inhibited by 30 mM L-phenylalanine (L-Phe), a specific inhibitor for intestinal ALP. As body weight increased from 150 g to 300 g, total daily ALP activity in fecal extracts decreased rapidly to 33.7 +/- 6.08 mumoles/min/rat. However, the percentage of L-Phe-sensitive ALP to total enzyme activity was less variable (40-65%) in the growing rats. Cysteamine-HCl, an ulcerogenic drug, was injected subcutaneously to adult rats (300 g b. w) at a dosage of 400 mg/kg. b. w. Daily excretion of L-Phe-sensitive ALP in fecal extracts decreased to one-third 2 days after injection. Afterwards, a steep and transient increase in the enzyme activity was detected in fecal extracts between days 4 and 7 after injection. ALP activity in fecal excretions may be a clinical indicator of duodenal mucosal damage.

Alkaline Phosphatase↗
PubMed1988

Hydrolysis of alpha-D-glucopyranosyl-1,6-sorbitol and alpha-D-glucopyranosyl-1,6-mannitol by rat intestinal disaccharidases.

The hydrolyzing activities in rat small intestine for newly developed sugar substitutes, alpha-D-glucopyranosyl-1,6-sorbitol (GPS) and alpha-D-glucopyranosyl-1,6-mannitol (GPM), both of which are produced by hydrogenation of palatinose, were characterized. GPS and GPM were hydrolyzed in mucosal homogenate as well as in brush border membranes of rat small intestine at a slower rate than the rate of hydrolysis of palatinose (30%) and sucrose (6-7%). Gel filtration column chromatography of disaccharidases solubilized from brush border membranes revealed that GPS and GPM were hydrolyzed mainly by sucrase-isomaltase complex and its degradation product, i.e. isomaltase monomer. The isomaltase monomer, purified from small intestine of rats, possessed similar Km values for GPS (2.47 mM) and GPM (5.38 mM) as compared to those of purified sucrase-isomaltase complex. The Vmax values of isomaltase monomer for GPS and GPM were twice as high as those of sucrase-isomaltase, suggesting that GPS and GPM are hydrolyzed by the active site of isomaltase. On the other hand, a small amount (up to 17%) of GPS- and GPM-hydrolyzing activities was ascribed to glucoamylase, which possessed relatively high Km values for GPS (18.7 mM) and GPM (32.9 mM). To examine a physiological significance of GPS- and GPM-hydrolyzing activities, the transmural potential difference (delta PD) evoked by Na+-dependent active transport of glucose, produced by the hydrolysis of these disaccharide alcohols, was measured in everted segments of rat jejunum. The relative rates of absorption of glucose produced by the hydrolysis of GPS and GPM were 36% and 27% of that of palatinose, directly reflecting the hydrolyzing activities determined in jejunal homogenate. These results suggest that the process of hydrolysis is the rate limiting step in digestion-absorption process of palatinose, GPS and GPM in small intestine.

Animals↗
PubMed1988

Changes in glucose uptake by and phlorizin binding to brush-border membrane vesicles of small intestine from streptozotocin-induced diabetic rats.

The changes in the intestinal glucose transport in streptozotocin-induced diabetic rats have been demonstrated with brush-border membrane vesicles. When Na+-dependent D-glucose uptake and phlorizin binding activities were compared, both significantly increased either in the jejunum or ileum of diabetic rats compared with those of control. Kinetic studies showed the increases in the Vmax of glucose transport and the maximum binding of phlorizin (Bmax), whereas the Kt and Kd remained unchanged, respectively. These results suggested that the increase in glucose transport in diabetic rat intestine was due to the increase in the number of the intact glucose transporters.

Animals↗
PubMed1987

Possible role of insulin status in the increased lipogenic enzyme activity by dietary medium-chain triglyceride in rat liver.

The possible role of insulin status in the increase in liver lipogenic enzyme activities upon feeding medium-chain triglyceride (MCT) was investigated with streptozotocin-induced diabetic rats and insulin-treated diabetic rats. Rats were fed synthetic diets that contained either 2% corn oil (control), fat free, 13% MCT +2% corn oil, or 13% lard +2% corn oil, respectively. Feeding the MCT diet for 3 days increased serum ketone bodies in both the normal and diabetic rats. Insulin levels of MCT-fed rats tended to be higher than in normal animals. MCT feeding caused an enhancement of fatty acid synthetase (FAS) and malic enzyme (ME) in the liver of normal rats, whereas diabetic rats failed to register an increase in those activities due to MCT feeding. Administration of insulin to diabetic rats resulted in a recovery of the level of those enzyme activities to about the same degree as in each of the normal rat groups. It was interesting that diabetic MCT-fed rats with insulin treatment maintained higher enzyme activities in comparison to the lard and control groups. These results suggest that the increase in lipogenic enzyme activities caused by dietary MCT is presumably dependent on differences in insulin status.

Animals↗
PubMed1986

Solubilization of 1,25-dihydroxyvitamin D3 receptor with pyridoxal 5'-phosphate from hen intestinal mucosa.

1,25-Dihydroxyvitamin D3(1,25-(OH)2D3) receptor was solubilized in cytosol fractions upon homogenization of hen intestinal mucosa with pyridoxal 5'-phosphate contained in a low ionic strength buffer. Pyridoxal 5'-phosphate did not inhibit the binding of 1,25-(OH)2D3 to its receptor. The receptor solubilized with pyridoxal 5'-phosphate was similar to the KCl-solubilized receptor in its binding affinity to the hormone and sedimentation coefficient. A majority (greater than 90%) of the mucosal 1,25-(OH)2D3 receptors were obtained as associating with crude chromatin which was prepared with a low ionic strength buffer, and this fraction of the receptor was solubilized with pyridoxal 5'-phosphate. Ten millimolar pyridoxal 5'-phosphate was as effective as approx 0.2 M KCl in solubilizing the receptor from the crude chromatin. Pyridoxal 5'-phosphate also showed a potency to dissociate the 1,25-(OH)2D3-receptor complex previously bound to DNA-cellulose. Pyridoxal 5'-phosphate-related compounds such as pyridoxamine 5'-phosphate and pyridoxal did not show this potency. These results suggest that pyridoxal 5'-phosphate reduced the interaction of 1,25-(OH)2D3 receptor with its nuclear binding components without inhibiting the binding of the receptor to the hormone.

Animals↗
PubMed1986

Influence of chronic intake of new sweetener fructooligosaccharide (Neosugar) on growth and gastrointestinal function of the rat.

The influence of the chronic intake of a newly developed sweetener named "Neosugar" (fructooligosaccharide) on body weight gain, organ weight, serum lipids, fecal excretion and intestinal function was investigated in rats. The following results were obtained. Body weight gain was diminished more severely in rats fed on 20% Neosugar diet than in rats fed on 10% Neosugar diet. The wet weights of cecum and colon were greatly increased by Neosugar feeding. Fecal wet weight was significantly increased and gastrointestinal transit time was shortened by Neosugar feeding compared with those of the control group. Serum triacylglycerol levels were significantly lower in rats fed Neosugar, whereas serum cholesterol levels were similar to those of the control group. Fecal excretions of neutral sterol and volatile fatty acids were significantly increased by Neosugar feeding. These results were quite similar, with the exception of diarrhea to those obtained using a dietary fiber such as glucomannan. Therefore, Neosugar with a pleasant-tasting sweetness appears to be an unavailable oligosaccharide with a dietary-fiber-like action.

Animals↗
PubMed1986

Regulatory effect of calcium-regulating hormones on the synthesis and/or secretion of bone gamma-carboxyglutamic acid-containing protein in chick embryonic calvaria in vitro.

Regulatory effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2-D3), 24,25-dihydroxyvitamin D3 (24,25-(OH)2-D3), parathyroid hormone (PTH) and calcitonin (CT) on BGP synthesis and/or secretion were studied using chick embryonic calvaria in vitro. BGP contents in calvaria and culture medium were determined by radioimmunoassay using antiserum to purified chick BGP. After 72 h culture, 1,25-(OH)2-D3 (10(-10)-10(-7) M) increased the BGP content in culture medium significantly, and the effect was maximum at 10(-8)M, while the BGP content in calvaria was not changed by 1,25-(OH)2-D3. 24,25-(OH)2-D3 increased the BGP content both in medium at 10(-6) M-10(-5) M after 24 h culture and in calvaria at 5 X 10(-7)-10(-5) M after 48 h culture. PTH increased BGP contents both in calvaria after 72 h culture and medium at 1 U/ml after 24 h culture, while it decreased them at 5-10 U/ml after 24 h culture. CT (0.5-10 U/ml) had no effect on BGP contents in calvaria and medium. 1,25-(OH)2-D3-induced increase of BGP in culture medium was observed from 24 to 72 h of culture and then reached a plateau at 120 h of culture. 1,25-(OH)2-D3-induced increase in the BGP level in medium after 72 h culture was 3-4 times the control value. On the other hand, the BGP content in calvaria was not affected by 1,25-(OH)2-D3 until 72 h of culture and then significantly increased at 120 h. The addition of 1,25-(OH)2-D3 (10(-8) M), 24,25-(OH)2-D3 (10(-6) M), and 1 U PTH (and 1 U CT added to those hormones) into culture medium of chick embryonic calvaria significantly increased BGP contents in calvaria and medium at 72 h after culture. The effect of three hormones was not synergistic, but had a tendency to be greater than that of a single addition of 1,25-(OH)2-D3, 24,25-(OH)2-D3 or PTH. Further addition of 1 U CT into culture medium did not affect the combined effects of 1,25-(OH)2-D3, 24,25-(OH)2-D3 and PTH except for the calcium content in calvaria. The addition of individual calcium-regulating hormones into culture medium of chick embryonic calvaria did not affect the calcium and phosphorus contents in calvaria, but the calcium content in calvaria was significantly increased by the addition of 1,25-(OH)2-D3, 24,25-(OH)2-D3 and PTH to the culture medium.(ABSTRACT TRUNCATED AT 400 WORDS)

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Effect of dietary vitamin D3 and cadmium on the lipid composition of rat intestinal brush border membranes.

Vitamin D deficiency in cadmium-exposed rats was observed along with enhanced tissue cadmium accumulation. In relation to the barrier function, the changes in the lipid composition have been studied in the intestinal brush border membranes prepared from rats raised on diets differing in vitamin D status in the absence or presence of cadmium. In an analysis of lipid composition, vitamin D3 treatment resulted in an increase of phospholipid content, and cadmium ingestion resulted in a decrease of cholesterol and glycolipid contents in the duodenal brush border membranes. On the other hand, vitamin D3 and cadmium showed no significant effect on the lipid composition of the jejunal brush border membranes. Further analysis of the fatty acid composition in duodenal brush border membrane lipids showed that vitamin D3 treatment led to an increase of the proportion of fatty acids (18:1 and 18:2 in the total and phospholipid fraction) and also shorter chain fatty acids in neutral lipid fractions in the absence of cadmium. However, vitamin D3 treatment in the presence of cadmium led to a decrease of the proportion of fatty acid (18:2 in the total and phospholipid fraction) and also shorter chain fatty acids in neutral lipid fractions. Vitamin D-dependent alterations of the membranes might act as a barrier in cadmium-exposed rats.

Animals↗
PubMed1986

Effect of dietary medium chain triglyceride on lipogenic enzyme activity in rat liver.

This study was conducted to confirm that medium chain triglyceride (MCT) feeding itself would increase hepatic lipogenic enzyme activity without causing a lack of essential fatty acids (EFA) in the liver. Male weaning rats were fed for 11 weeks on diets containing 2% corn oil and 13% various fats: MCT, corn oil, tripalmitin or beef tallow, respectively. MCT feeding was clearly shown to increase the activities of fatty acid synthetase (FAS) and malic enzyme (ME) in the liver. Rats weighing 170 g were pair-fed for 7 days on diets containing 15% MCT, 13% MCT + 2% corn oil, 15% corn oil, and 2% corn oil and no fat (control groups), respectively, under a fixed level of carbohydrate (sucrose). The addition of 2% corn oil to MCT (13%) did not depress these enzyme activities, even though supplementing the fat-free diet with 2% corn oil resulted in a significant decline in the activities. When the rats received various amounts of MCT, the extent to which the degree of FAS and ME activities increased by MCT feeding depended on the amount of MCT in the dietary fat mixture with corn oil. Supplement of over 5% corn oil to MCT diets did not inhibit them sufficiently. In the liver lipids of animals fed MCT, there were no appearances of 20:3 omega 9 (5,8,11-eicosatrienoic acid), but the levels of mono-unsaturated fatty acids were increased by MCT feeding. The results suggest that MCT ingestion itself enhances lipogenic enzyme activity via some metabolic charge.

Animals↗
PubMed1986

Digestion and absorption of sugars and sugar substitutes in rat small intestine.

The bioavailability of newly developed sugar substitutes was observed by measuring the transmural potential difference (delta PD) evoked by Na+-dependent active transport of glucose, which is supposed to be produced by the hydrolysis of sugar substitutes. delta PD was measured using everted intestinal sac prepared from jejunum of adult rats and compared with the digestibility of sugar substitutes in the mucosal homogenate of everted sac. delta PDs evoked by glucose, maltose or maltosylfructose had almost the same levels, however, the delta PD evoked by sucrose was a little lower. delta PDs evoked by maltitol or palatinose were low, and delta PDs evoked by fructo-oligosaccharides were negligible. The hydrolyzing activities of these sugars and sugar substitutes by the mucosal homogenate were correlated with the delta PDs. A significant positive correlation was observed between delta PDmax of various sugars and sugar substitutes and the Vmax of their corresponding hydrolyzing activities. Also, a significant positive correlation was observed between Kt and Km values of these sugars. These results suggest that the absorption of sugar substitutes is dependent on digestibility by membrane digestive enzymes.

Animals↗
PubMed1986

Multiple form of L-phenylalanine sensitive alkaline phosphatase in rat fecal extracts.

Alkaline phosphatase activity was detected in fecal extracts of male rats. 58% of the total enzyme activity was inhibited by 30 mM L-phenylalanine, which is an inhibitor specific for intestinal alkaline phosphatase. L-Phenylalanine sensitive alkaline phosphatase in the fecal extracts revealed multiple peaks on DEAE-Sephadex A-25 ion exchange column with a linear gradient of NaCl. It is discussed that a part of the fecal alkaline phosphatase might be a set of catabolites of the intestinal enzyme.

Alkaline Phosphatase↗
PubMed1985

Functional disability of rat splenocytes provoked to lipid peroxidation by cumene hydroperoxide.

Rat splenocytes were provoked to lipid peroxidation in a dose-dependent manner by cumene hydroperoxide. After exposure to cumene hydroperoxide, formation of high molecular weight protein, presumably through cross-linking of lower molecular weight protein, was stimulated in splenocytes as well as in erythrocyte ghosts. The mitogenic response to concanavalin A of splenocytes was remarkably depressed by addition of cumene hydroperoxide to cultures. This depression was due rather to failures of splenocytes in responding to concanavalin A than deactivation of concanavalin A molecules. It is notworthy that the viability of splenocytes was unaffected by cumene hydroperoxide under the culture conditions where the mitogenic response was depressed. The addition of alpha-tocopherol or thiourea could block the depression of mitogenic response by cumene hydroperoxide, indicating that the depressed response to concanavalin A was related to radical formation. Overall evidence suggests that the function of immunocompetent cells can be depressed through lipid peroxidation-associated mechanisms without suffering from lethal damage.

Animals↗
PubMed1985

The effect of 1,25-dihydroxycholecalciferol on the changes of bone gamma-carboxyglutamic acid-containing protein in bone and serum of developing chick.

The effects of 1,25-dihydroxycholecalciferol(1,25-(OH)2-D3) injection into developing chick embryos on bone gamma-carboxyglutamic acid-containing protein (BGP) levels in bone and serum were observed in relation to those on calcium metabolism using chick embryos and chicks aged from 13 days' incubation to 7 days of age. Chick BGP was determined by radioimmunoassay using antiserum to purified chick BGP. The injection of 1,25-(OH)2-D3 into the developing chick embryos of 13 days' incubation resulted in the increases of bone BGP levels at hatching and at 2 days of age. However, the distribution of bone BGP at hatching was not influenced by 1,25-(OH)2-D3. On the other hand, serum BGP levels were significantly increased by 1,25-(OH)2-D3 at 14, 15, 18 days' incubation and at 2 days of age. The early changes of serum BGP levels after 1,25-(OH)2-D3 treatment were correlated with the increases of serum calcium concentrations and the decreases of inorganic phosphorus concentrations. These results suggest that 1,25-(OH)2-D3 may directly or indirectly mediate BGP synthesis or secretion associated with calcium metabolism.

1-Carboxyglutamic Acid↗
PubMed1985

Some properties of luminal sucrase and sucrase-isomaltase complex in rat small intestine.

Some properties of luminal sucrase-isomaltase complex and the effect of luminal fluid on their complex were studied in rat small intestine. Luminal contents were collected by flushing the small intestine with the buffered solution. The enzyme activity was observed in luminal contents and intestinal mucosa. Sucrase and isomaltase activities were located mainly in the intestinal mucosa. However, approximately 20% of sucrase and 10% of isomaltase activities of total small intestine were found in the luminal contents. A significant amount of sucrase without isomaltase activity, the molecular weight of which was estimated at about 140,000 daltons, was found in the luminal supernatant of the distal intestine in addition to the complexed form of sucrase and isomaltase. The luminal sucrase and sucrase-isomaltase complex had similar properties such as Km values, optimal pH, molecular weights and antigenicity against anti sucrase-isomaltase antibody compared with brush border membrane-bound sucrase-isomaltase complex. Furthermore, the supernatant of the luminal contents of the ileum had a degradative effect on the isomaltase moiety of the purified sucrase-isomaltase complex and a free sucrase without isomaltase also appeared in vitro as observed in vivo. These results suggest that the sucrase-isomaltase complex is released into the intestinal lumen from the brush border membrane and that a luminal factor affects the degradation step of this enzyme as well as the biosynthesis of sucrase-isomaltase complex.

Animals↗
PubMed1985

Changes of sugar-evoked transmural potential differences in intestine of rats with streptozotocin-induced diabetes.

The changes of the transmural electrical potential difference (delta PD) evoked by infusion of glucose, maltose and sucrose and the disaccharidase activities in the everted intestine were studied in diabetic rats. After the induction of diabetes by streptozotocin, delta PDs evoked by sugars and the enzyme activities were observed in the jejunum and ileum. delta PDs evoked by glucose, maltose and sucrose markedly increased both in the jejunum and ileum of diabetic rats. The Kt values for these sugars in diabetic rats were the same as those of control rats. The Vmax values were significantly increased in the ileum of diabetic rats. Maltase and sucrase activities in the ileum increased in diabetic rats. Highly significant linear correlations were found between the delta PDs evoked by glucose and the delta PDs evoked by maltose or sucrose both in the jejunum and ileum of control and diabetic rats. However, delta PDs evoked by maltose and sucrose did not correlate with maltase and sucrase activities in the jejunum. In the ileum, delta PDs evoked by sucrose correlated with the sucrase activity which was very low. These results suggest that the increase of transport of glucose derived from disaccharides in the diabetes induced by streptozotocin is mainly due to the increased activity of the glucose transport system, but not due to the increase of disaccharidase activities.

Animals↗