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Biomedical subjects

K Uenishi

Publications and source records attributed to K Uenishi.

14 recordsLinked to original sources
PubMed2001

Calcium requirement estimated by balance study in elderly Japanese people.

The recommended dietary allowance (RDA) for calcium (Ca) of Japanese adults is proposed to be 600 mg/day, which is lower than those of other countries. In this report we estimated the Ca requirement and the RDA for Ca in elderly Japanese utilizing a Ca balance method. Subjects were 10 men aged 65-72 years and 10 women aged 62-77 years. Following a 14 day adaptation period, each participant was subjected to a low Ca diet (Ca 250 mg as a meal) for 6 days. After an interval of 2 weeks or more, another 14 day adaptation period was set and then a high Ca diet (Ca 250 mg as a meal and 600 mg as CaCO3) was served to the subjects for 6 days. Ca balance was calculated at each dose of Ca intake. Ca requirement was estimated by the intersection of the average Ca intake-retention diagram. Daily Ca requirement was 702 mg in the men and 788 mg in the women. The Ca requirement values were multiplied by 1.2 to obtain the RDA for Ca. As a result, RDA for Ca was 842 mg/day for men and 946 mg/day for women. When these values were normalized with the body weight, the RDA for Ca of Japanese and Caucasian women was similar (18.1 and 18.5 mg/kg body weight per day, respectively). Our results suggest the difference in Ca balance between the genders and among populations may be ascribed at least partly to differences in body size. In addition, body weight should be considered when comparing the RDAs among different populations.

Aged↗
PubMed2001

[Not Available].

Explore the source record for details and available documents.

Journal Article↗
PubMed2001

[Intestinal calcium absorption].

Calcium which is required by our body must be absorbed from the diet through the intestine. Food and body conditions influence on calcium absorption from the intestine. Even when the same diet is eaten, the calcium absorption rate is different in each subject. It is assumed that calcium absorption is affected by many factors including acidity in the stomach, transit time of the intestine, intestinal flora, vitamin D, PTH and the other hormones.

English Abstract↗
PubMed1995

Studies on antiulcer agents. II. Antiulcer properties of N-(1H-tetrazol-5-yl)-2-anilino-5-pyrimidinecarboxamides inhibiting release of histamine from passively sensitized rat peritoneal mast cells.

With the aim of applying mast cell-stabilizing agents as antiulcer agents, N-(1H-tetrazol-5-yl)-2-anilino-5-pyrimidinecarboxamides were synthesized, and initially evaluated pharmacologically for activity in the rat passive cutaneous anaphylaxis test by oral administration. The most active compound 6 was proved to inhibit potently the release of histamine from passively sensitized rat peritoneal mast cells in vitro. When compared with other mast cell-stabilizing agents and an antiulcer agent, compound 6 was found to show excellent gastric mucosal protection and gastric antisecretion activities. Furthermore, compound 6 revealed good activity against acidified aspirin ulcer in rats and water-immersion stress ulcer in rats.

Animals↗
PubMed1995

Studies on antiulcer agents. I. Synthesis and pharmacological properties of ethyl 2-[(1H-benzimidazol-2-yl)sulfinylmethyl]-4-dimethylamino-5- pyrimidinecarboxylate, a new H+/K(+)-ATPase inhibitor possessing mucosal protective activity.

Ethyl 2-[1H-benzimidazol-2-yl)sulfinylmethyl]-4-dimethylamino-5- pyrimidinecarboxylate (2) has been synthesized and evaluated for antiulcer properties. Compound 2 is a H+/K(+)-ATPase inhibitor that affords mucosal protection against absolute ethanol-induced gastric lesions in rats after oral and parenteral administrations. On the other hand, omeprazole, a representative H+/K(+)-ATPase inhibitor, showed mucosal protective action only after oral administration, indicating that it required gastric acid secretion to generate activity. The antiulcer activity of 2 in animal models, such as water-immersion stress-induced gastric ulcer in rats and acidified aspirin-induced gastric ulcer in rats, was three times higher than that of cimetidine.

Animals↗
PubMed1993

Effect of excess phenylalanine diet during pregnancy on fetal brain growth in rats.

The effects of 10 and 20% casein diets containing 7% phenylalanine (Phe) during pregnancy on fetal brain growth were examined in rats. Control pregnant rats were fed the casein diets ad libitum or in restricted amounts. Total food intakes during 21-day period in the Phe excess groups decreased to about 50% of those of the liberally fed control groups. In control rats given 10 and 20% casein diets, fetal brain weights (Y, mg) were significantly and hyperbolically correlated to total food intakes (g/21 days), conforming to the following equations: Y = -10283/X + 130.5 (n: 13, r = 0.89, p < 0.001) and Y = -4396/X + 130.4 (n: 15, r = 0.68, p < 0.005), respectively. Similar plots for rats fed 10 and 20% casein diets with Phe fell below these lines, meaning that fetal brain growth was impaired by both the decreased food intake due to excess Phe (nonspecific effect) and the toxicity of excess Phe per se (specific effect). Total amounts of RNA and protein and protein/DNA ratio decreased in the fetal brain from excess Phe dams, suggesting that protein synthesis of brain cells was disturbed. This may be partly due to the disruption of normal patterns of free amino acids observed in the fetal brains. Reduction of total DNA was also seen in fetal brain from excess Phe groups, meaning impaired proliferation. From above findings we concluded that proliferation and hypertrophy were impaired in fetal brain from excess Phe dams.

Amino Acids↗
PubMed1993

Effect of dietary proteins on zinc bioavailability in pregnant rats.

In order to clarify the effects of dietary proteins on zinc bioavailability during pregnancy, two experiments were carried out. In Experiment 1, changes in zinc retention due to pregnancy (difference in retention between pregnant and nonpregnant animals) during early-mid and late pregnancy were examined in rats fed 10 and 20% egg white diets. Total amounts of retained zinc due to pregnancy were about 1000 micrograms or slightly more, equal to the zinc content in the products of conception at term. However, extra zinc retention during late pregnancy ranged between only 20 to 40% of overall retention, suggesting that almost all zinc retained during early-mid pregnancy moved from the mothers to the fetuses near term. Zinc retention in early-mid and late periods of pregnancy was higher in pregnant than nonpregnant rats, due mainly to increases in intake and bioavailability. In Experiment 2, to examine the effects of quality and quantity of dietary proteins, pregnant rats were fed either 10 or 20% egg white (EW), whole egg (WE), casein (C) and soy protein isolate with or without methionine (SM and S, respectively) diets. Total zinc retention during pregnancy was affected by both zinc and nitrogen intakes, though the former effect was greater than the latter. Because rats fed the EW diets retained dietary zinc efficiently, a relationship between zinc retention (Y, microgram/100 g BW/21 d.) and zinc intake (X, microgram/100 g BW/21 d.) was also examined in the non-EW protein groups, resulting in the following regression equation: Y = 0.471X-1790 (n: 51, r = 0.81, p < 0.001). Dietary protein quality affected the food intake resulting in different zinc intake and retention during pregnancy. Zinc from EW diets was more available than from the other four protein diets, because similar plots for rats fed the 10 and 20% EW diets fell above this line. Reasons for efficient bioavailability of zinc in EW were discussed in connection with the forms of zinc in diets and the pancreatic or intestinal responses to ingested EW.

Animals↗
PubMed1993

Nutritional improvements of soy protein isolate by different levels of methionine supplementation in pregnant rats.

The effects of various levels (0, 0.3, 0.4, 0.5, 0.7, 1.0 and 1.5%) of methionine supplementation to a 10% soy protein isolate (SPI) diet were investigated in pregnant and nonpregnant rats in terms of body weight gain, food efficiency, net protein utilization (NPU), growth of the conceptuses and free methionine concentration in the dam's plasma. Supplementation of 0.3 to 0.7% methionine resulted in increases in the weights of the body, fetus and placenta and improvements of food efficiency and NPU in both groups of rats. The extents of increases or improvements of these parameters were more in pregnant rats than in nonpregnant rats, though they were similar in each group independent of the dietary methionine level. No beneficial effects on body weight gain, food efficiency or reproductive performance were observed in rats fed diets with 1.0 or 1.5% methionine. The concentrations of free methionine in the plasma were increased by methionine supplementation to the diet and were consistently higher in nonpregnant rats than in pregnant rats at each level of methionine supplementation. From these results, we proposed that a level of 0.5% methionine (intermediate between 0.3 to 0.7%) is optimal for supplementing 10% SPI diet for rats. The appropriateness of this level is discussed in relation with the methionine equipment of growing rats.

Animals↗
PubMed1978

Identification of an activator protein for myosin light chain kinase as the Ca2+-dependent modulator protein.

Myosin light chain kinase which phosphorylates g2 light chain of skeletal muscle myosin requires an activator for the activity (Yazawa, M., and Yagi, K (1977) J. Biochem. (Tokyo) 82, 287-289). This activator has now been identified as the modulator protein known to be a Ca2+-dependent regulator for phosphodiesterase, adenylate cyclase, and ATPases. The identification is based on the quantitative cross-reactivity of muscle activator protein and brain modulator protein in activating myosin light chain kinase and brain phosphodiesterase and identical properties of both proteins in regard to sensitivities to Ca2+, UV absorption spectra, UV absorption difference spectra with or without Ca2+, and mobilities upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the presence of modulator protein, the activity of myosin light chain kinase was reversibly controlled by the physiological concentration of Ca2+. We suggest that two Ca2+-receptive proteins, i.e. modulator protein and troponin-C, may play roles in the contraction-relaxation cycle of skeletal muscle.

Animals↗
PubMed1975

Multiple cyclic nucleotide phosphodiesterase activities from rat tissues and occurrence of a calcium-plus-magnesium-ion-dependent phosphodiesterase and its protein activator.

1. Supernatant fluids from rat cerebral cortex, cerebellum, kidney, heart and liver contained more phosphodiesterase activity hydrolysing cyclic GMP than that hydrolysing cyclic AMP when assayed with sub-saturating concentrations of substrate. 2. These activities were resolved into several fractions by Sephadex G-200 gel filtration; no two tissues had similar activity profiles. 3. With every tissue examined, a fraction (fraction II) with a molecular weight of about 150,000 was obtained which hydrolysed cyclic GMP preferentially at sub-saturating substrate concentrations in the presence of micromolar concentration of Ca2+, millimolar concentration of Mg2+ and a protein activator. 4. The activity of fraction II accounted for about 60 percent in liver, more than 80 percent in heart and cerebellum, and almost 100 percent in cerebral cortex of the total activity for cyclic GMP hydrolysis, calculated from the activity profiles. 5. Km values of fraction II samples from kidney, heart and liver for cyclic GMP were 1.3, 1.7 and 5 muM respectively. 6. 3-Isobutyl-1-methylxanthine inhibited hydrolysis of cyclic GMP by fraction II with an I50 value of 3muM for heart and liver and 50 muM for cerebrum. 7. The activator protein, with an estimated molecular weight of about 30,000 was isolated from all the tissues listed in 1.8. The concentrations of activator protein and of the isolated enzyme, fraction II, did not correspond exactly.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1975

Ca-2+/Mg-2+-dependent cyclic nucleotide phosphodiesterase and its activator protein.

(1) Ca-2+/Mg-2+-dependent cyclic nucleotide phosphodiesterase was found in the supernatant fluids of a variety of tissues, including cerebral cortex, cerebellum, kidney, liver, and heart. (2) this enzyme required Ca-2+, Mg-2+, and an activator protein (PAF) for the activity. In the presence of these ingredients the enzyme hydrolyzed cyclic GMP preferentially when incubated with a low concentration (0.4 muM) of substrate. (3) The enzyme devoid of PAF was eluted in fraction II with a molecular weight of approximately 150,000 after Sephadex G-200 gel filtration of the supernatant fluids using medium containing EGTA. PAF thus separated from the enzyme was eluted in a fraction corresponding to a molecular weight of approximately 28,000 by gel filtration. Stimulation of the activity of fraction II by Ca-2+ was completely dependent on the addition of PAF. (4) Formation of an active enzyme-PAF complex with an estimated molecular weight of 200,000 was demonstrated by gel filtration of a mixture of the enzyme and PAF in medium containing Ca-2+. It is likely that the activity of the Ca-2+/Mg-2+ in a concentration range of approximately 1 to 10 muM, as shown in the following equation: [Enzyme] inactive + PAF + Ca-2+ in equilibrium [enzyme - PAF - Ca-2+] active. More than one PAF protein may bind to one molecule of enzyme to form an active complex. Equilibrium of the above equation is probably determined mainly by the intracellular concentration of Ca-2+ in vivo. (5) The enzyme-PAF complex was more labile after heat treatment than the free form of enzyme. (6) PAF was isolated from all tissues listed in (1). The levels of PAF and of fraction II did not correspond exactly.

Animals↗
PubMed1973

Regulation of nucleoside cyclic 3':5'-monophosphate phosphodiesterase activity from rat brain by a modulator and Ca2+.

Gel filtration of the 40,000 rpm supernatant fraction of a homogenate of rat cerebral cortex on a Sepharose 6B column yielded two fractions: fraction II with the "Ca(2+) plus Mg(2+)-dependent" phosphodiesterase activity and fraction III containing its modulator. The activity of fraction II was stimulated by micromolar concentrations of Ca(2+) and the modulator when present together; the modulator stimulated the activity of fraction II only when the Ca(2+) concentration was above a threshold value (about 2 muM with 0.4-1 muM substrate), and the stimulatory effect of Ca(2+) was dependent upon the presence of the modulator. A possibility is discussed that the modulator may reversibly bind to the enzyme, which by itself is inactive, to form an active enzyme-modulator complex and that Ca(2+) stimulates the activity of phosphodiesterase by shifting the equilibrium between these three species towards the formation of the active enzyme-modulator complex. Although fraction II hydrolyzed both cyclic AMP and cyclic GMP, hydrolysis of the latter was more significantly influenced by Ca(2+) and the modulator than that of the former, and the "Ca(2+) plus Mg(2+)-dependent" phosphodiesterase is likely to be a cyclic GMP enzyme. This conclusion is based on the following evidence: (a) Ca(2+) stimulated hydrolysis of cyclic GMP by fraction II more than that of cyclic AMP. (b) In the presence of Ca(2+) and the modulator, fraction II hydrolyzed cyclic GMP about 8 times faster than cyclic AMP when incubated with 0.4 muM substrate. (c) Half-maximal stimulation of hydrolysis of cyclic GMP was attained at a lower concentration of Ca(2+) (4 muM) than that of cAMP (8 muM). (d) Increase in the concentration of Ca(2+) from 0.06 muM to 12 muM in the presence of the modulator caused a decrease in the K(m) value of cyclic GMP hydrolysis by fraction II from 20 muM to 2 muM accompanied by 4-fold increase in the V(max) value. Under similar conditions, there was only a slight decrease in the K(m) value of cylic AMP hydrolysis (90 muM --> 50 muM), although the V(max) value increased 7-fold. The anomalous shape of the kinetic plot of cyclic GMP hydrolysis became linear when the Ca(2+) concentration was increased in the presence of the modulator. The modulator seems to be a protein, but it is heat stable. It is probably identical to the protein activator of phosphodiesterase first described by Cheung.

Animals↗