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Predecessor
Volume 57, Issue 1
Displaying 1-8 of 8 articles from this issue
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Involvement of Phosphatidylinositol 3-kinase Activation in Acute Metabolic Effect of Insulin on Glucagon-induced Glucose ReleaseToshiaki Tanaka, Yoshimichi Someya, Mica Imaizumi, Hidenori Katsuta, S ...2004 Volume 57 Issue 1 Pages 1-7
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSIt has been demonstrated that hepatic glucose metabolism and glycogen synthesis is essential for the maintenance of glucose homeostasis in vivo. However, the precise mechanism for regulation of the metabolic system in hepatocytes is still unclear at the cellular level. In the present study, we developed a new highly sensitive assay system for glucose, based on the combination of an enzyme immobilization column and an electrochemical detector. The minimum detection limit of this system was 10nM, and the coefficient of inter-assay variance was 1.9%. This assay system was then applied to the measurement of glucose released from rat primary cultured hepatocytes in vitro. Stimulation with 10-12-10-8M glucagon increased the release of glucose from hepatocytes in a dose-dependent manner. In the presence of 10-9M glucagon, 10-12-10-5M insulin reduced glucagon-induced glucose release dose-dependently in an hour. The inhibitory effect was found to be significant (p<0.05) when 10-7-10-5M insulin was added to the medium. In addition, both 10-6M wortmannin and 10-4M LY294002, inhibitors of phosphatidylinositol 3-kinase (PI3K), significantly suppressed the inhibitory effect of 10-7M insulin on enhanced glucose release by 10-9M glucagon (p<0.05). These results clearly indicate that the acute metabolic effect of insulin in isolated hepatocytes is mediated, at least partly, through the phosphorylation cascade of insulin signalling via PI3K activation.View full abstractDownload PDF (1235K) -
Yoshiaki Maeda, Yoshiko Aoyama, Shiro Goto, Syoji Azami2004 Volume 57 Issue 1 Pages 9-13
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSThe objective of this experiment was to determine calcium (Ca) balance and the kidney content of Ca in young male Wistar, Fischer, Sprague-Dawley and Donryu rats fed a high-phosphorus (P) diet in the form of Harpers' salt. During the three weeks of the experiment, each of the four rat strains was fed a diet containing either 0.5% or 1.5% P, and urine and fecal samples were collected in the final week. Food intake in all strains was significantly decreased by the high-P diet, and food intake differed among the strains. The effect of the high-P diet on Ca utilization showed that the Ca balance was not significantly modified in Wistar and Sprague-Dawley rats, but Ca absorption and retention were significantly increased in Fischer rats and significantly decreased in Donryu rats. The kidney content of Ca in all strains was significantly increased by the high-P diet, and the kidney Ca content varied among the strains. The effects of dietary P on Ca utilization cannot always be duplicated among different rat strains, but an increase of calcification can be promoted by a decrease of food intake. We suggest that the effect of high dietary P on Ca utilization is closely related to a decrease of food intake.View full abstractDownload PDF (782K) -
Tsuyoshi Watanabe2004 Volume 57 Issue 1 Pages 15-19
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSOver the last 50 years since the end of World War II, the incidence of diabetes mellitus and hyperlipidemia has increased dramatically in Japan. Although the incidence of hypertension had been decreasing in association with decreased salt intake until the mid-1980s, it has increased slightly because of a return rend to re-increase in salt intake since 1988, and insulin resistance-related hypertension has begun to predominate over salt-sensitive hypertension in the total hypertensive population. The reason for this increase in lifestyle-related diseases is that the Japanese have become an aged and obese population, with accumulation of visceral fat, because of the westernized lifestyle characterized by high consumption of animal fat and decreased physical activity. As a result, atherosclerosis-related diseases such as myocardial infarction and cerebral infarction as well as microangiopathic diseases such as diabetic complications and benign nephrosclerosis have increased, and are now the most important medical and social problem to be solved from the standpoints of mortality, quality of life and medical finance. Thus, lifestyle modifications such as appropriate calorific intake containing a low level of animal fat, aerobic exercise and stress management should be promoted as a financially effective and medically powerful strategy for reducing the number of patients with diabetes mellitus, hyperlipidemia and hypertension.View full abstractDownload PDF (847K) -
Preventive Effects of Tea Catechins on Atherosclerosis and Cerebral Ischemic DamageTakako Tomita2004 Volume 57 Issue 1 Pages 21-26
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSGreen tea catechins possess potent antioxidative properties, and the preventive effects against various oxidative diseases have been reported. Oxygen radicals in the subendothelial spaces and the penumbra around occluded brain area, play a crucial role in the initiation mechanism of atherosclerosis and stroke, respectively. The purpose of this study was to examine the protective and preventive effects of green tea catechins on atherosclerosis and stroke. Individual pure components of green tea catechins were tested for antiplatelet aggregation property; EGCg and ECg showed 5- and 4-fold potency compared with aspirin. Catechins, especially EGCg and ECg, strongly prevented copper-mediated oxidation of low-density lipoproteins (LDL) in vitro. One-week ingestion of green tea extract significantly prolonged the lag time of LDL oxidation in humans. A long time ingestion of catechin extract greatly prevented the development of atherosclerosis in apoE-deficient mice. In addition, catechin extract protected against cerebral ischemic damage in mid-cerebral artery occluded and reperfused rats; it reduced the score of neurological deficit, reduced brain infarct volume depending on plasma EGCg concentration, and inhibited iNOS expression, neutrophill accumulation and peroxynitrite formation in the penumbra. These results suggest that tea catechins exert beneficial effects on cardiovascular diseases, and support the results of various epidemiological investigations.View full abstractDownload PDF (2608K) -
Yasuo Kagawa2004 Volume 57 Issue 1 Pages 27-33
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSLifestyle-related diseases are the outcome of both nutritional and genetic factors. The genetic factors are due mainly to single-nucleotide polymorphisms (SNPs). SNPs including beta-adrenergic receptor, uncoupling proteins 2 and 3p, PPAR-gamma, and leptin receptor are responsible for obesity and diabetes. Westernization of lifestyle and diet has a strong impact. We have studied SNPs in mongoloids because of their rapid increase in diabetes resulting from westernization. SNPs responsible for saving energy-the so-called called “thrifty SNPs” (Biochem Biophys Res Commun 295: 207-222, 2002)-were found in PPAR-gamma 2, UCP3 promoter, leptin receptor etc. Using mailed swab DNA samples, we also analyzed SNPs of individuals who had been educated 25-31 years previously. Despite differences in SNPs (UCP3p, UCP2, apoE and mtDNA), the special dietary habits (four-group point method) and exercise practiced by these individuals prevented most of the lifestyle-related diseases. A diabetes prevention program to encourage effective habit change is an important activity of registered dieticians.View full abstractDownload PDF (1293K) -
Young Investigator Award of the 2003's JSNFSTakanori Tsuda2004 Volume 57 Issue 1 Pages 35-43
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSAnthocyanins are used for food coloring, and are widely distributed in human foods, suggesting that we ingest large amounts of anthocyanins from plant-based foods. However, anthocyanins have not been recognized as a physiologically functional food factor. In in vivo (rat and human) studies, we have demonstrated that anthocyanins are potent physiological functional food factors that are absorbed and metabolized. Dietary cyanidin 3-glucoside (C3G), one of the typical anthocyanins, functions as a potent antioxidant in vivo (liver ischemia-reperfusion and zymosan-induced inflammation system in rats). We have also demonstrated the absorption and metabolism of C3G and delphinidin (Del) derivatives in rats and humans. C3G was degraded to protocatechuic acid and metabolized to methylated C3G in rats. In the human study, C3G, Del 3-glucoside and Del 3-rutinoside were also directly absorbed and distributed to the blood. Based on our results, C3G is expected to have more beneficial effects beyond its antioxidant activity. We demonstrated that dietary C3G-rich purple corn coloring suppressed the development of obesity and ameliorated hyperglycemia induced by a high-fat diet in mice. Our findings provide a biochemical and nutritional basis for the use of anthocyanins as a functional food factor, which can also have important implications for the development of physiological functional foods.View full abstractDownload PDF (5012K) -
Young Investigator Award of the 2003's JSNFSSatoshi Ishizuka2004 Volume 57 Issue 1 Pages 45-50
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSDisruption of the maintenance of intestinal epithelial homeostasis results in many intestinal disorders. It is suggested that intraepithelial lymphocytes (IELs) contribute to this homeostasis through their involvement in the elimination of abnormal epithelial cells. Some forms of dietary fiber inhibit the decrease in the number of CD8+ IELs by anti-asialo GM1 administration to maintain epithelial homeostasis. Even under physiological conditions, some fermentable forms of dietary fiber modify the distribution of IELs and natural killer cells in the large intestine. This suggests that the epithelium selects the type of intraepithelial lymphocytes according to the type of dietary fiber ingested. It is considered that dietary fiber modulates the distribution of IELs and natural killer cells in the epithelial layer via luminal fermentation.View full abstractDownload PDF (4641K) -
Young Investigator Award of the 2003's JSNFSHiroyuki Takeuchi2004 Volume 57 Issue 1 Pages 51-58
Published: February 10, 2004
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSControl of body fat accumulation by dietetics is very important from a viewpoint of lifestylerelated disease prevention. We studied the effects of molecular species of dietary fat on body fat accumulation. Intake of saturated fatty acids, compared with that of unsaturated fatty acids, decreased diet-induced thermogenesis by a decline of sympathetic activity, reduced Na+, K+-ATPase activity by lowering the level of serum thyroid hormone, and increased the activity of lipoprotein lipase in adipose tissue, thus promoting the accumulation of body fat. In a double-blind, controlled trial in healthy subjects, dietary medium-chain triacylglycerols suppressed the accumulation of body fat. Suitability of medium-chain triacylglycerols for high-temperature cooking was vastly improved by transesterification with long-chain triacylglycerols. Diet-induced thermogenesis was greater for ester-exchange triacylglycerols than for long-chain triacylglycerols in healthy humans. We also demonstrated that ester-exchange triacylglycerols suppressed the accumulation of body fat in healthy subjects. These results suggest not only the quantity but also the quality of fat intake needs to be considered in diet management for obesity prevention.View full abstractDownload PDF (1270K)
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