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Biomedical subjects

Y Itokawa

Publications and source records attributed to Y Itokawa.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of thiamine supplementation on exercise-induced fatigue.

High-dose thiamine (vitamin B1) supplementation (100 mg/day) may be helpful in preventing or accelerating recovery from exercise-induced fatigue. Sixteen volunteer male athletes volunteer, 8 with a blood thiamine level of 40 ng/ml or more (normal thiamine group) and 8 with levels below that level (low thiamine group) were selected as subjects. They exercised on a bicycle ergometer and the effects of thiamine supplementation were compared with placebo. Blood thiamine level markedly increased following supplementation of thiamine for 3 days before exercise. Exercise-induced changes in hemodynamic parameters and cardiopulmonary function indicated the onset of fatigue. Thiamine supplementation significantly suppressed the increase in blood glucose in the normal thiamine group and significantly decreased the number of complaints shortly after exercise in the subjective fatigue assessment of 30 items.

Adult↗
PubMed1996

The effects of isomaltulose, isomalt, and isomaltulose-based oligomers on mineral absorption and retention.

We carried out a balance study to examine the effects of isomaltulose, lactose, isomalt, and isomaltulose-based oligomers (IBOs) on mineral (calcium, magnesium, phosphorus, and iron) absorption and retention. Four-week-old male Wistar rats were divided into five groups of six rats each and fed a basal diet or diet the containing either 5% isomaltulose, 5% lactose, 5% isomalts or isomaltulose-based oligomers (IBOs) ad libitum for 16 d. After 1 wk, the animals were subjected to a 5-d mineral (calcium, magnesium, phosphorus, and iron) balance study. The isomalt feeding, as well as the IBOs feeding, led to significantly elevated mineral absorption and retention. On the other hand, lactose feeding, widely known to enhance calcium absorption, increased only calcium absorption and isomaltulose feeding did not affect mineral absorption or retention. The organic acids in cecum contents were increased by IBOs or isomalt feeding. Succinic and acetic acids in cecum contents were significantly increased by IBOs feeding. Similarly, succinic, acetic, and i-valeric acids and total amount of organic acid in cecum content were significantly increased by isomalt feeding. Although the organic acids in cecum contents were increased by IBOs or isomalt feeding, the pH values and acidity in cecum contents were not changed by IBOs or isomalt feeding. The effect of addition of various organic acids to the mucosal fluid was examined with in vitro study using a hindgut segment. By the addition of acetic acid, and butyric acid, the mineral (calcium, magnesium, and phosphorus) uptake was increased.

Animals↗
PubMed1996

Neurological disorder and excessive accumulation of calcium in brain of clinically vitamin A-deficient rats.

Three groups of rats were fed two types of synthetic diets for 52 d. The -A group was allowed free access to a vitamin A-deficient diet and showed classical signs of vitamin A deficiency. The brain was the only organ in our experiment where no significant weight difference was present among the three groups. In the brain, calcium concentration was significantly higher in the -A group when compared with the PF (Pair-fed; allowed restricted amount of control diet) and +A groups (allowed free access to control diet). In the tibia, calcium and magnesium concentrations were significantly lower in the -A group when compared with other two groups. Excessive accumulation of calcium in brain and apparently similar unbalance in bone mineral concentration were observed in central nervous system (CNS) degenerative diseases. Our results suggest that abnormal metabolism of calcium and magnesium in some tissues and excessive accumulation of calcium in brain may be responsible for the development of neurological disorders in vitamin A-deficient rats.

Animals↗
PubMed1996

Effect of age and dietary protein level on tissue mineral levels in female rats.

Mineral (phosphorus, sulfur, potassium, calcium, magnesium, iron, zinc, copper, and manganese) concentrations were measured in plasma, and several tissues from female Wistar rats (young: 3-wk-old; mature: 6-mo-old) were fed on a dietary regimen designed to study the combined or singular effects of age and dietary protein on mineral status. Three diets, respectively, contained 5, 15, and 20% of bovine milk casein. Nephrocalcinosis chemically diagnosed by increased calcium and phosphorus in kidney was prevented in rats fed a 5% protein diet. Renal calcium and phosphorus were more accumulated in young rats than mature rats. A 5% protein diet decreased hemoglobin and blood iron. The hepatic and splenic iron was increased by a 5% protein diet in mature rats but was not altered in young rats. Mature rats had higher iron in brain, lung, heart, liver, spleen, kidney, muscle, and tibia than young rats. A 5% protein diet decreased zinc in plasma and liver. Zinc in tibia was increased with dietary protein level in young rats but was not changed in mature rats A 5% protein diet decreased copper concentration in plasma of young rats but not in mature rats. Mature rats had higher copper in plasma, blood, brain, lung, heart, liver, spleen, and kidney than young rats. With age, manganese concentration was increased in brain but decreased in lung, heart, liver, kidney, and muscle. These results suggest that the response to dietary protein regarding mineral status varies with age.

Aging↗
PubMed1996

Effect of low dietary rubidium on plasma biochemical parameters and mineral levels in rats.

The effects of low dietary rubidium on plasma biochemical parameters and mineral levels in tissues in rats were studied. Eighteen male Wistar rats, weighing about 40 g, were divided into two groups and fed the diets with or without supplemental rubidium (0.54 vs 8.12 mg/kg diet) for 11 wk. Compared to the rats fed the diet with supplemental rubidium, the animals fed the diet without rubidium supplementation had higher urea nitrogen in plasma; lower rubidium concentration in tissues; lower sodium in muscle; higher potassium in plasma, kidney and tibia, and lower potassium in testis; lower phosphorus in heart and spleen; lower calcium in spleen; higher magnesium in muscle and tibia; higher iron in muscle; lower zinc in plasma and testis; and lower copper in heart, liver, and spleen, and higher copper in kidney. These results suggest that rubidium concentration in tissues reflects rubidium intake, and that rubidium depletion affects mineral (sodium, potassium, phosphorus, calcium, magnesium, iron, zinc, and copper) status.

Animals↗
PubMed1996

Apoptosis induced by selenium in human glioma cell lines.

Several studies have shown that selenium can inhibit tumorigenesis in tissues. However, little is known about the mechanism and the effect of selenium on DNA, especially in brain tumor cells. In this study we examined the biological effect of selenium on human glioma cell lines (A172 and T98G). Selenium exhibited an antiproliferative effect on these cell lines (and induced the typical ladder pattern of DNA fragmentation commonly found in apoptosis), which were prevented by catalase. Few effects of selenium on NT14 fibroblasts were found. These findings demonstrate that selenium may induce, by apoptosis, cell death of human glioma cell lines, which are resulting from free radical oxygen forming.

Apoptosis↗
PubMed1996

The effect of palatability and feeding conditions on digestive functions in rats.

OBJECTIVE: Information concerning various post prandial gastrointestinal functions modulated by taste stimulation is rather limited. Thus, effects of different types of palatability and feeding condition on digestive functions were studied. METHODS: Male Sprague-Dawley rats were divided into two different feeding groups, meal feeding and ad libitum. In meal feeding, the daily feeding period was shortened gradually and was restricted eventually only 3 hours. In ad libitum feeding, food was freely available for 24 hours until experiment. After each rat in both feeding groups was fed 8.29 mM saccharin or 1.28 mM quinine flavored diet as a taste stimulant for 15 minutes, changes of gastric and intestinal nitrogen and pH and pancreatic amylase activities were compared with meal feeding vs ad libitum feeding. RESULTS: In meal feeding, no difference was observed between before and after taste stimulation or between saccharin and quinine flavored diets on gastric and intestinal nitrogen contents, pH in the stomach and in the small intestine, and amylase activity. On the other hand, in ad libitum feeding, intestinal nitrogen contents tended to stagnate until 60 minutes after tasting quinine, although there was little difference between saccharin and quinine diets on gastric nitrogen contents. Gastric juice was hardly secreted before tasting (pH 6.2) and then pH in the stomach changed to become more acid following taste stimulation. Although amylase secreted in small intestine was hardly secreted before tasting, activities after tasting saccharin were increased immediately and lasted until 120 minutes. Amylase activity in rats fed the quinine diet, however, showed slower increase and faster recovery than that in rats fed the saccharin diet. CONCLUSIONS: The results confirmed that various postingestive functions after taste stimulation depend on feeding conditions and it suggests that the ad libitum feeding condition is more appropriate than meal feeding on the experiment related to gustatory response.

Animals↗
PubMed1996

The effects of isomaltulose-based oligomers feeding and calcium deficiency on mineral retention in rats.

We examined the effects of isomaltulose-based oligomers (IBOs) on the mineral content of the whole blood, kidney, liver and tibia in calcium deficient and calcium sufficient rats. Twenty-eight Wistar rats were divided equally into 4 groups and fed with the following diets ad libitum for 4 weeks: (1) calcium sufficient diet (Ca+, IBOs-), (2) calcium-sufficient-IBOs supply diet (Ca+, IBOs+), (3) calcium-deficient diet (Ca-, IBOs-), (4) calcium-deficient-IBOs supply diet (Ca-, IBOs+). There were no significant differences in final body weights among the groups. Food consumption in the calcium-deficient groups was higher than that in the calcium-sufficient groups. The tibia weight was significantly decreased, and the calcium, magnesium and phosphorous contents significantly decreased, and iron content was significantly increased in the tibia of calcium-deficient rats. On the other hand, in IBOs feeding rats, tibia weight, and calcium, magnesium and phosphorous contents were significantly increased, and iron content was significantly decreased. These findings suggest that IBOs feeding improves mineral retention especially in a state of calcium deficiency.

Animals↗
PubMed1996

[Trace elements in long-term total parenteral nutrition].

Deficiency symptoms of trace elements developed in patients receiving long-term total parenteral nutrition (TPN) are as follows. [Zinc deficiency]: moist eczematoid dermatitis and alopetia are occurred in patients receiving TPN which not containing zinc. Plasma zinc level was very low. The response to intravenous zinc therapy is striking. [Copper deficiency]: anemie and neutropenia caused in patients receiving TPN which not containing copper. These abnormalities disappeared after copper therapy. [Manganese deficiency]: bone changes which thought to be due to manganese deficiency was observed in patient receiving TPN. [Selenium deficiency]: dilated cardiomyopathy resembles to Keshan disease was occurred in patients receiving TPN for long term. [Chromium deficiency]: TPN induced chromium deficiency developed characterized by peripheral neuropathy and glucose intolerance. [Molybudenum deficiency]: Amino acid intolerance due to molybudenum deficiency is occurred in patients receiving TPN. Requirement of trace elements for human adults from TPN estimated as follows. zinc: 3-4 mg/day, copper: 0.02-0.05 mg/day, iron: 1-2 mg/day, manganese: 0.15-0.80 mg/day, selenium: 0.02-0.05 mg/day, chromium: 0.01-0.015 mg/day, molybudenum: 0.075-0.250 mg/day and iodine: 0.070-0.140 mg/day.

Adult↗
PubMed1996

Effect of long-term administration of finasteride (MK-906), an inhibitor of 5 alpha-reductase, in patients with benign prostatic hyperplasia.

We evaluated the effect of long-term administration of finasteride (MK-906), a potent inhibitor of 5 alpha-reductase in patients with benign prostatic hyperplasia (BPH). The effect of an increase in dose was also assessed. Finasteride was administered to 61 patients with BPH at the dose of 1 mg/day for 48 weeks. Thirty three of these patients subsequently received finasteride at the dose of 5 mg/day for further 24 weeks in an open extension study. Urinary symptoms, urinary flow rate, residual urinary volume, prostatic volume and serum concentrations of dihydrotestosterone and prostate-specific antigen were examined periodically during the treatment. The size of the prostate and total urinary symptom scores decreased progressively during the first 16 weeks of treatment. The patients who received finasteride had a significant increase in the maximal urinary flow rate and a significant decrease in residual urinary volume. After 72 weeks of treatment, finasteride at an increased dose of 5 mg did not provide additional benefit to patients, although the effects of the drug at a dose of 1 mg were well maintained. Treatment with finasteride was well tolerated at both doses. In conclusion, the treatment of BPH with 1 mg of finasteride per day for 48 weeks results in a significant increase in maximal urinary flow rate, and a decrease in prostatic volume, symptoms of obstruction and residual urinary volume, with minimal toxicity.

5-alpha Reductase Inhibitors↗
PubMed1996

Changes of phylloquinone and menaquinone-4 concentrations in rat liver after oral, intravenous and intraperitoneal administration.

To study the metabolism of K Vitamins (VK) in the liver, two types of natural VK, phylloquinone (K1) and menaquinone-4 (MK-4), were administered to male Wistar rats orally (P.O.), intravenously (I.V.) and intraperitoneally (I.P.). Blood and a small portion of the liver (and ascites by I.P.) were collected 8 times up to 72 h (P.O.) or 24 h (I.V. and I.P.). A modified assay procedure followed by high performance liquid chromatography (HPLC) was developed to detect VK from small amounts of liver tissue. After oral administration of both K1 and MK-4 (10 mumol/kg-P.O.), their concentrations in the liver increased from 1 h then reached a maximum at 6 h (10 nmol/g v.s. 0.35 nmol/g). After intravenous or intraperitoneal administration of K1 and MK-4 (0.5 mumol/kg-I.V. and I.P.), MK-4 concentrations in the liver reached a maximum faster than those of K1 (1.2 nmol/g -3 h vs. 1.3 nmol/g -0.5 h I.V. and 0.97 nmol/g -6 h vs. 0.47 nmol/g -1 h I.P.). MK-4 also increased in the liver from 6 h to 12 h (0.11 nmol/g -12 h) after oral administration of K1 (P.O.). These results indicate that K1 stays in plasma and liver longer than MK-4 and orally administered K1 might be transformed partially into MK-4 in the liver.

Animals↗
PubMed1995

Effect of selenium on malignant tumor cells of brain.

Some reports have demonstrated that selenium can inhibit tumorigenesis in some tissues of animal. However, little is known about the inhibitory effect on malignant tumor cells of brain. The purpose of our study was to determine the biological effect of selenium on growth of rat glioma and human glioblastoma cell lines. Cell lines C6 and A172 were obtained from Japanese Cancer Research Resources Bank, Tokyo, Japan (JCRB). Cells were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal calf serum at 37 degrees C in a humidified atmosphere of air and 5% CO2. Antiproliferative effects of selenium were evaluated using growth rate assay quantifying cell number by MTT assay. An antiproliferative effect of selenium was found in two cell lines, which was more effective on human A172 glioblastoma and less effective on rat C6 glioma.

Animals↗
PubMed1995

Iron, zinc, and copper levels in different tissues of clinically vitamin A-deficient rats.

To clarify the effect of vitamin A deficiency on iron, zinc, and copper status in different tissues, three groups of rats were fed two types of synthetic diets for 52 d. Group one, which was fed a vitamin A-deficient diet, showed severe signs of vitamin A deficiency. Groups two (fed restricted amount, pair-fed with group one), and three (fed diet ad libitum) were fed a control diet. After said period of feeding, iron, zinc, and copper were measured in different tissues. Significant changes observed when the groups were compared are summarized below: 1. Iron and copper in testes were increased significantly, whereas zinc was strikingly decreased in group one when compared with the other groups; 2. Copper (in lung and kidney) and iron (in the spleen) were increased significantly in group one compared with the other groups; 3. In the liver, iron, zinc, and copper were significantly different between group one and group two; 4. In muscle, iron was significantly higher in group one than group two; 5. In tibia and blood, iron levels (but not zinc and copper) in groups one and two were significantly higher than group three. These results suggest that vitamin A deficiency affects iron, zinc, and copper status in rats.

Animals↗
PubMed1995

Uptake and distribution of sodium selenite in rat brain tumor.

Eighteen weanling male Wistar rats with brain gliomas were divided into three groups, which received 0., 2.0, 5.0 ppm selenium (Se) in their drinking water. The accumulation and retention of selenium in the brain bearing tumor was investigated. Significantly higher concentrations of Se were observed in tumor tissue than normal brain tissue after exposure to sodium selenite. Tumors were observed in the 2.0 micrograms/g selenium group. The difference in selenium concentration between the tumor tissue and contralateral normal brain tissue was not influenced by the weight of brain or body, and water consumption. We observed that selenium accumulated in tumor tissue more than in normal brain tissue.

Administration, Oral↗
PubMed1995

Iodothyronine deiodinase activity in methionine-deficient rats fed selenium-deficient or selenium-sufficient diets.

We examined the effect of methionine deficiency on iodothyronine 5'-deiodinase activity in selenium-deficient rats or selenium-sufficient rats fed sodium selenate or selenomethionine. Forty-two weanling male Wistar rats were divided into six groups and pair fed the respective purified L-amino acid-based diets for 4 wk. L-methionine concentrations in the diet were 8.0 g/kg for sufficient rats, and 2.0 g/kg for deficient rats. Selenium concentrations in the diet were 0.5 mg/kg (as sodium selenate or selenomethionine) for selenium-sufficient rats and less than 0.005 mg/kg for selenium-deficient rats. Type I 5'-deiodinase activities were significantly lower in liver and higher in kidney of methionine-deficient rats than in those of methionine-sufficient rats fed either the selenium-sufficient or the selenium-deficient diets. The type I 5'-deiodinase activity in brain was significantly lower in the methionine-deficient rats than in the methionine-sufficient rats fed the selenium-deficient diet. Type II 5'-deiodinase activity in brain was significantly higher in the methionine-deficient rats than in the methionine-sufficient rats fed selenium-sufficient diet as sodium selenate. Both thyroxine and 3,3',5-triiodothyronine concentrations in plasma were significantly higher in the methionine-deficient rats than in the methionine-sufficient rats. It is suggested that the methionine deficiency affects the 5'-deiodinase activity and thyroid hormones level in the rats.

Animals↗
PubMed1995

Decline of taste sensitivity in protein deficient adult rats.

The influence of dietary protein levels on taste sensitivity was studied in adult rats. Low protein diets of 0.0, 2.5, or 5.0% purified egg protein (PEP) were fed to animals for 28 days. Two bottle choice preference tests between aqueous solutions of either 2, 9, 17, or 86 mM sodium chloride and deionized water were conducted in an ascending order on days 14, 16, 18, and 20. Urine samples were collected for zinc and creatinine analysis. Blood samples were also collected for measuring serum zinc and creatinine concentrations. Scanning electron microscopy was performed to observe rats' tongue epithelia. Protein free diet group showed significantly lower taste sensitivity and renal reabsorption rate than other protein containing diet groups, while serum zinc and creatinine concentrations, and creatinine clearance were not affected by dietary protein level. Degeneration of filiform papillae and imperforation of taste pore of fungiform papillae were observed in protein free diet group. This experiment implies at least 2.5% dietary protein is required to manifest normal taste function in the adult.

Age Factors↗
PubMed1995

Changes of K vitamins in portal and femoral venous plasma of rats after oral administration of phylloquinone and menaquinone-4.

To clarify the mechanism of absorption and metabolism of K vitamins (VK), we administered phylloquinone (K1) and menaquinone-4 (MK-4) orally to male Wistar rats whose portal and femoral veins were cannulated. Blood was collected 9 times up to 120 min later, and 50 microliters plasma was used for VK analysis by high performance liquid chromatography (HPLC) using a modification of our previous method. There were no significant differences between portal and femoral venous VK concentrations throughout all the experiments. When K1 and MK-4 were administered simultaneously, K1 appeared in plasma at 15 min, and MK-4 at 10 min. The concentration of MK-4 was significantly higher than that of K1 up to 60 min. In contrast to the single administration, the MK-4 concentration was reduced after 60 min. After K1 single administration, the MK-4 was not detected in either portal or femoral venous plasma up to 120 min. These results suggested that (1) the main absorption route of both VK may be the extra-portal pathway, (2) MK-4 is absorbed faster than K1 (3) some interactions may exist between K1 and MK-4 and (4) the intestinal cells might not be the major site to transform K1 into MK-4.

Administration, Oral↗