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Volume 49, Issue 1
Displaying 1-8 of 8 articles from this issue
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From Circadian Rhythms to Regulated DegradationShin-ichi HAYASHI1996 Volume 49 Issue 1 Pages 1-11
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSThis paper summarizes the results of my quarter-century study on the regulatory mechanism of ornithine decarboxylase (ODC), a key enzyme in polyamine synthesis. ODC turns over rapidly and is under negative feedback regulation by polyamines, which accelerate ODC degradation and induce an ODC-inhibitory protein, antizyme. Rat-liver ODC levels exhibit a circadian rhythm with the peak at night, owing to the feeding pattern. The dietary induction of hepatic ODC depends on both the quantity and quality of dietary proteins. In order to clarify the molecular mechanism of ODC regulation, rat-liver ODC was purified to homogeneity. Antizyme was also highly purified and its cDNAs were obtained. Forced expression of antizyme caused rapid ODC degradation, proving that antizyme mediates polyamine-induced destabilization of ODC. In newly established in vitro ODC degradation systems, ODC is degraded in an ATP- and antizymedependent manner by 26 S proteasome without ubiquitination. Antizyme also inactivates polyamine uptake. Nucleotide sequence analysis of antizyme mRNA revealed that programmed ribosomal frameshifting evoked by polyamines is necessary for its translation.View full abstractDownload PDF (6392K) -
Tsuyoshi NAKAMURA, Naoki HAYASHI, Daiji YOSHIHARA, Minoru YANAI, Yasuy ...1996 Volume 49 Issue 1 Pages 13-21
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSThe effect on diarrheal incidence in enterectamized rats enterally fed a liquid diet of either perilla oil [α-linolenic acid (α-LnA) /linoleic acid (LA) =3.26], or corn oil [α-LnA/LA=0.03], or both oils mixed together [α-LnA/LA=0.323] was examined, together with the effect on the transit time through the digestive tract, and the effect on prostaglandin (PGE2 and PGF2α) and fatty acid concentrations. The incidence of dierrhea in the groups fed perilla oil or mixed oil was significantty lower than in the corn oil-fed group. Perilla oil or mixed oil-feeding resulted in longer transit times compared with corn oil-feeding. The concentrations of PGE2 in plasma and the colonic mucosa were lower in the perilla oil-fed group than in the coroil-fed group, while eicosapentaenoic acid levels in the colonic mucosa were higher in the perilla oil-fed group. These results indicate that an enterally-fed liquid diet enriched with α-LnA may prevent diarrhea after operatians af the digestive tract accompanied by suppression of the motility of the digestive tract and alteration of the metabolism of fatty acids.View full abstractDownload PDF (3033K) -
Tetsuo MURAKAMI, Kazuo YAMAMOTO, Norifumi SHIRASAKA, Hajime YOSHIZUMI1996 Volume 49 Issue 1 Pages 23-28
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSStroke-prone spontaneously hypertensive rats (SHRSP) were fed a diet with fishmeal as the protein source (fish diet) from 10 weeks until 30 weeks of age. The effect of the diet on endothelium-dependent relaxation of the mesenteric artery, the resistance of which is known to reflect the pathology of hypertension, was studied and compared with the effects of captopril (an ACE inhibitor) and hydralazine (a vasodilator), both of which are antihypentensive drugs. Mesenteric artery preparations were precontracted with noradrenaline (8×10-6 M) and, when the contraction had reached a steady state, the tissue was perfused with acetylcholine (10-6 M) to induce endothelium-dependent relaxation. The relaxation rate in the fish-diet group was 66±8%, which was higher (p<0.05) than that in the control group (33±12%), and was close to that of normo-tensive Wistar-Kyoto rats (70±7%). On the other hand, in the endothelium-dependent relaxation rates of the drug-treated groups were 61±4% in the captopril group, and 54±5% in the hydralazine group, and these rates were higher (p<0.05) than that of the control group. From these results, it is clear that the impairment of endothelium-dependent relaxation in SHRSP is improved, independently of a blood-pressure drop, by nutritional improvement with a fish diet.View full abstractDownload PDF (4851K) -
Studies on the Nutritive Value of Grass Proteins (Part XXX)Tadahiko YASUI1996 Volume 49 Issue 1 Pages 29-37
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSThis work was undertaken to clarify the effect of pretreatment with dilute HCl solutions on the extractability of true proteins from grasses. After the materials were soaked in 0.5-2N HCl solutions at 22°C for 1-21 days, or at 38°C for 1-24h proteins were extracted from the grasses with 0.05N NaOH solutions. Using this procedure, the extractabilities of grass proteins were markedly increased. The highest values obtained were: red clover 66%, spinach 86%, cabbage 94%, Italian rye grass 79%, leaf of Japanese radish 90%, and so on. The pretreatment at 38°C brought about a marked reduction in the time required for successful protein extraction.View full abstractDownload PDF (1484K) -
Junko SUZUKI, Namiko KUROYANAGI, Yasuko MATSUTANI, Naga ITO1996 Volume 49 Issue 1 Pages 39-45
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSThe effects of physical exercise and dietary fats on blood pressure and lipid metabolism were studied using spontaneously hypertensive rats (SHR). The animals, aged 5 weeks, were fed two semipurified, fat-laden diets containing 1) 10% lard (L-diet) and 2) 10% safflower oil (S-diet) followed by a 15-week exercise program (from 11 weeks of age). Body weight, blood pressure and serum lipid levels were measured. The average body weight was greater than that of nonexercised rats. Blood pressure in the exercised groups for both diets was significantly lower than that in the non-exercised groups. Serum lipid levels, including total lipids, total cholesterol, triglyceride and free fatty acid of exercised L-diet rats were clearly lower than in the non-exercised L-diet rats. These parameters for the exercised S-diet rats were also lower, but were not significantly different, except triglyceride. The serum triglyceride level in the exercised rats was significantly lower than in the non-exercised rats for both diets, w ereas HDL-C in the exercised rats was higher for both diets. Physical exercise was thus shown to be effective for lowering hypertension and suppressing hyperlipemia due to dietary fats.View full abstractDownload PDF (2571K) -
Toshiaki AOYAMA, Kensuke FUKUI, Takashi YAMAMOTO1996 Volume 49 Issue 1 Pages 46-51
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSThe gastric transit times of force-fed proteins, peptides and amino acids were compared in rats. The nitrogen sources used were lactalbumin or casein (protein), enzymatic hydrolysate of soy protein (peptide) and an amino acid mixture simulating the composition of the soy peptide. The solutions, containing 25% or 10% of the nitrogen sources (N × 6.25), were prepared and 1 ml or 2.5 ml per 100 g body weight was force-fed. The gastric transit time of the peptide medium was the fastest. The amino acid medium increased the volume in the stomach above the initial volume within 2 h of force-feeding. The peptide solution, which contained more nitrogen and had a higher osmotic pressure than the amino acid solution, showed a gastric transit time similar to that of the amino acid solution. These results indicate that the gastric transit time of peptides is shorter than that of other nitrogen sources, which may be due not only to the influence of osmotic pressure and molecular size but also to other, unknown mechanisms.View full abstractDownload PDF (832K) -
Megumi UEHARA, Mari TANAKA, Isao CHINEN, Fujiya HONGO, Hiroko SHO1996 Volume 49 Issue 1 Pages 52-56
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSNagakonbu (Laminaria angustata var. longissima Miyabe) and Okinawa-tofu are frequently consumed by aged persons in Okinawa. In this study the effects of Nagakonbu and Okinawa-tofu on bone metabolism in ovariectomized rat were examined. Six-week-old Wistar-strain female rats were divided into ovariectomized and shamtreated groups. Thereafter a control group was fed a “CaCO3 diet” (0.2% Ca, 0.15% P) and the experimental groups were fed either the “Nagakonbu diet” (0.2% Ca, 0.1% P), or the “Okinawa-tofu diet” (0.2% Ca, 0.2% P) ad libitum for 35 days. The calcium absorption of the ovariectomized rats fed the Okinawa-tofu diet was significantly lower than that of rats fed the CaCO3 or Nagakonbu diets. On the other hand, the calcium content of the left femurs of ovariectomized rats fed the Nagakonbu or Okinawa-tofu diets was significantly higher than those of rats fed the CaCO3 diet. In addition, greater strength, stiffness and toughness (mechanical properties) of the femurs was also observed in Nagakonbu diet-fed rats. These results suggest that Nagakonbu and Okinawa-tofu may be suitable as a source of dietary calcium.View full abstractDownload PDF (891K) -
Kazuharu SUZUKI, Yosiaki MAEDA, Mariko UEHARA, Shiro GOTO1996 Volume 49 Issue 1 Pages 57-60
Published: December 10, 1996
Released on J-STAGE: February 22, 2010
JOURNAL FREE ACCESSEffects of dietary phosphate levels and phosphate sources on iron utilization were studied. Seventy-two Wistar-strain male rats (70g body weight) were divided into 12 groups. Each group was fed one of four phosphate sources, either KH2PO4, K5P3O10, NaH2PO4 or Na5P3O10, and the diet was supplemented to approximately 0.5%, 1.0% or 1.5% P. Results: 1) The high dietary phosphate level (1.5%) resulted in significant decreases in weight gain, food intake and nitrogen retention. 2) Absorption and retention of Fe decreased, and urinary excretion increase, with increasing P intake by K2P3O10 and Na5P3O10 feeding.View full abstractDownload PDF (551K)
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