Norimasa Hosoya

Metabolic pathways of glucose in human placenta

Abstract Slices of human placenta taken at term or at 10 to 16 weeks of gestation were incubated with one of several 14 C-labeled substrates. The conversion of 14 C to products was measured. From these data the fractions of glucose metabolized in the Embden-Meyerhof pathway, the pentose phosphate pathway, the glucuronic acid cycle, and the non-triose phosphate pathway were calculated. Estradiol added to slices of young placenta increased the uptake and utilization of glucose and the formation of glycogen and glycerol. The experiments show that the pattern of glucose metabolism in the placenta changes markedly in the course of gestation and becomes simpler in term placenta.

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.

Demonstration of immunoreactive retinol-binding protein and prealbumin in developing chicken embryo

Abstract The immunoreactive retinol-binding protein (RBP) and prealbumin (PA) were identified in chicken embryo by the method of double immunodiffusion using antisera against purified chicken serum RBP and PA, respectively. The embryonic RBP studied by a fluorospectrophotometric analysis showed presence of vitamin A (retinol) within the molecule. The RBP and PA fractionated on a column of Sephadex G-200 had molecular weight of approximately 20,000 and 56,000, respectively. RBP and PA formed a complex with vitamin A which had a molecular weight of approximately 76,000. The developmental changes of RBP and PA in the chicken embryo were determined in the eye, brain, serum and liver by the single radial immunodiffusion. In the brain and eye, the maxima for the concentration of RBP and PA were detected at day 6 for RBP, and day 6 and day 13 for PA during development. However, these proteins were not detected in the tissues of young chicken. The concentration of the serum embryonic RBP and PA showed a maximum at day 6. With regard to the liver, the PA was observed in the embryo only at day 13, but the RBP only after hatching.

Competitive protein-binding radioassay for retinoic acid

Rat testes cytosol treated by Blue Sepharose was employed in a simple and sensitive method for the determination of retinoic acid in the rat serum, liver, and intestine. The method permits the detection of as little as 3 ng of retinoic acid. The mean concentrations of retinoic acid in normal male rats were 33.5 ng/ml of serum, 624.9 ng/g wet wt of liver, and 444.3 ng/g of intestine.

Development of circadian rhythm of hepatic tyrosine aminotransferase in growing rats

Abstract DEVELOPMENTAL formation of circadian rhythm of hepatic tyrosine aminotransferase (TAT: EC 2.6.1.5.) activity was investigated in rats between day 3 and day 33 after birth. A diurnal change of TAT activity with low day time levels and high night-time values was initially recognized in rats between day 11 and day 15, the “eye-opening” stage. This diurnal variation of TAT activity became less evident during the weaning period due to a marked elevation of TAT activity throughout an entire 24 hour cycle. After the completion of weaning (day 27), however, a distinct circadian rhythm with a high amplitude of TAT activity was established, exhibiting a peak at the onset of darkness.

Comment Xylitol Effect on Ketogenesis in Alloxan Diabetic Rat Liver Slice

Haydon [1] has observed that xylitol is antiketogenic in liver slices of starved rats, and Bassler and Dreiss [2] also found that xylitol exerts antiketogenic action in alloxan diabetic rats. In this experiment xylitol effect on ketogenesis was studied in alloxan diabetic rat liver slices with palmitate-1-C14 used as substrate.

Present conditions and the future role of hospital dietitians in Japan

The primary role of dietitians in Japan has been as leaders in solving the food shortages caused by World War II. After 1970, dietitians were educated to promote health education and teach chronic disease prevention to the public. They have undertaken the responsibility to improve nutritional status of the community. Approximately 80% of dietitians in Japan are graduates of twoyear colleges. They work in food services and their job activities consist mainly of food-related activities and nutrition guidance to patients. They are not in charge of patients’ nutrition assessment or any other clinical dietetic practice. Recently, a number of attempts have been made to educate those who need to learn more about the clinical aspects of nutrition and to foster the development of clinical dietitians in Japan. Unfortunately, many problems remain to be solved in order to dramatically reform the education and practice of dietitians in this country.

Influence of calcium-binding protein in bovine milk on intestinal calcium absorption

In order to confirm the effect of calcium-binding protein in bovine milk (mCaBP) on intestinal calcium absorption, calcium transport was measured in the presence and the absence of exogenous mCaBP using the everted gut sac method and ligated-loop method. Exogenous mCaBP significantly stimulated the absorption of calcium in the lower ileum, but not in the duodenum in both vitamin D-deficient and normal rats only as determined by the ligated-loop method. These observations suggest that the stimulating mechanism of exogenous mCaBP for calcium transport is clearly different from that of vitamin D-dependent CaBP in intestinal epithelial cells, and that calcium transport in the lower intestine is effectively stimulated in the presence of both exogenous mCaBP and vitamin D-dependent CaBP. These results are tempting to suggest that mCaBP and vitamin D-dependent CaBP participate at the outside and the inside of epithelial cell, respectively, to stimulate intestinal calcium absorption, and both CaBPs interact each other in calcium transport system. The mechanism of mCaBP action in the intestine is still unclear.

Effect of Xylitol on the Metabolic Rate of Glucose in Alloxan Diabetic Rat Liver Slices

Glycogenic and glycolytic enzymes function systematically in the cell to establish the regulated flow of each of the metabolic pathways. Chaikoff et. al. [1] reported that enzyme activities of glycogenesis and glycolysis are markedly disturbed in the liver of alloxan diabetic rats. In order to elucidate the effect of xylitol on glucose metabolism [2], we have measured intermediates of glycogenesis and glycolysis in diabetic liver, in the presence or absence of added xylitol.

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.