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Masanori Ohta

Publications and source records attributed to Masanori Ohta.

10 recordsLinked to original sources
PubMed2006

Hindlimb unloading decreases thioredoxin-related antioxidant proteins and increases thioredoxin-binding protein-2 in rat skeletal muscle.

To investigate role(s) of thioredoxin-related antioxidant proteins in disuse muscle atrophy, we examined the levels of thioredoxin-1 (Trx-1), peroxiredoxin-3/SP-22 (Prx-3) and thioredoxin-binding protein-2 (TBP-2) in rat soleus muscle subjected to hindlimb unloading (HU) for 2, 4, 7 or 14 days. The muscle weight loss was initially observed on day 4. The increases in aclorein- and malondialdehyde-modified proteins, and the decreases in the levels of Trx-1, Prx-3 and Mn-SOD were observed in the late phase of muscle atrophy, whereas, the increase in mRNA expression of TBP-2, a negative regulator of thioredoxin, preceded muscle atrophy. These findings suggest that the decrease of those antioxidant proteins, particularly a marked decrease of Trx-1, may be responsible for the enhanced oxidative damage during the late phase of disuse muscle atrophy. Furthermore, the increase in TBP-2 preceding the muscle atrophy may suppress the thioredoxin-mediated redox signaling, which can be an initial trigger leading to disuse muscle atrophy.

Animals↗
PubMed2005

Blood pressure-lowering effects of lifestyle modification: possible involvement of nitric oxide bioavailability.

Lifestyle modification is recommended as a non-pharmacological approach to treatment of hypertension. Many investigators have reported that exercise has antihypertensive effects, and various mechanisms have been proposed to explain this phenomenon. For example, nitric oxide (NO), which may be increased by exercise, has been reported to play a crucial role in preserving vessel homeostasis both by regulating vascular tone and by exerting anti-atherosclerotic effects. NO is known to be exquisitely sensitive to inactivation by superoxide radicals. However, the relationship between the blood pressure-lowering effect of lifestyle modification and NO bioavailability remains unknown. We investigated the effects of a 12-week lifestyle modification program consisting of mild exercise and diet on changes in blood pressure, plasma nitrate/nitrite (NOx), plasma nitrotyrosine, which is the footprint of NO interaction with reactive oxygen species, and plasma extracellular-superoxide dismutase (EC-SOD). The 12-week lifestyle modification program lowered blood pressure and increased plasma NOx. When the subjects were divided into two groups according to the change of plasma nitrotyrosine as an indicator of NO bioavailability, the subjects whose plasma nitrotyrosine decreased exhibited a significant relationship between the blood pressure-lowering effect of the lifestyle modification and the increase in EC-SOD, whereas those without a decrease in plasma nitrotyrosine exhibited a significant relationship between the blood pressure-lowering effect and the increase in maximum oxygen consumption. These results indicate that the level of NO bioavailability influences the mechanism of the blood pressure-lowering effect of aerobic exercise and diet.

Adult↗
PubMed2005

Expression of small stress protein hsp20 gene in the maturing rat testis.

In this study, we cloned a cDNA that encodes a small heat shock protein, Hsp20 (alphaB crystallin-related protein), from a maturing rat testis by means of differential display. The full-length cDNA sequence was completely identical to that registered in the DNA databank. The expression of Hsp20 gene was detected strongly in the heart and slightly in the testis of a 9-week-old rat. The expression of Hsp20 increased gradually from three weeks to 9 weeks, and the strongest expression was observed in the testis at week fifteen. The expression was localized in spermatocytes and round spermatids. The gene expression was not affected by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) when it was administered into male rats during the nursling period.

Age Factors↗
PubMed2005

A novel spermatogenesis related factor-2 (SRF-2) gene expression affected by TCDD treatment.

We have cloned a gene which is specifically expressed at the stage of sexual maturation in the rat testis by means of differential display, and have named it spermatogenesis-related factor-2 (SRF-2). Testicular expression was first detected at 5 weeks of age, and its level of the expression increased up to 7 weeks, and was maintained even at 63 weeks. Its cDNA was 2,789 bp in length and encoded an open reading frame of 718 amino acids. This gene was mainly expressed in the spermatocyte, judging from the result of in situ hybridization. The hypothetical gene product had a motif highly homologous with RabGAP/TBC protein. Taken together, this gene is considered to have some important functions for meiosis. The gene expression was significantly decreased by treatment with TCDD, a candidate endocrine disruptor, when administered to male rats of the nursling period. Body weight and testis weight were decreased by the treatment, but even then the sperm concentration in cauda epididymis was not changed significantly. SRF-2 gene may be a promising biomarker to construct a detection system of uncertain endocrine disruptors.

Adenosine Triphosphatases↗
PubMed2004

The effect of lifestyle modification on physical fitness and work ability in different workstyles.

It is generally considered that physical fitness is affected by daily life activities including leisure time activity and working time activity. The aim of this study is to investigate the effects of different levels of physical activity at work on physical fitness, analyze the effects of 12-week lifestyle modification outside of working hours on physical fitness, work satisfaction and subjective symptoms, and to consider the role of lifestyle modification in occupational health. Lifestyle modification, consisting of aerobic exercise and diet counseling, was conducted for 12 weeks. The data before and after the intervention from 49 male workers were obtained. Physical fitness such as exercise endurance, flexibility, agility, balance, muscular strength, muscular endurance, and muscular power was measured before and after the intervention. The subjects were asked to fill out questionnaires about their work activities, subjective complaints, and work satisfaction. Subjects were divided into active work group (n = 14) and sedentary work group (n = 35) for analysis according to their work activities. As for differences in physical fitness due to different levels of physical activity, the active work group had superior exercise endurance and balance compared to the sedentary work group. In addition, the sedentary work group tended to experience greater fatigue than the active work group. In the active work group, flexibility and muscular strength were significantly increased with lifestyle modification and, in the sedentary work group, exercise endurance, flexibility and muscular endurance were significantly improved while balance also showed a tendency to improve. In the sedentary work group, lifestyle modification resulted in reduced fatigue and stiff neck as well as an increased work satisfaction. In the active work group, no change was observed in complaints or work satisfaction, but improved physical fitness led to a reduction in subjective complaints and an increase in work satisfaction. The level of physical activity at work contributes to the physical fitness of the worker and the addition of aerobic exercise in the worker's leisure time improves physical fitness and thereby contributes to increased work ability regardless of differences in the level of physical activity at work.

Hand Strength↗
PubMed2004

The prevention of colon carcinogenesis in rats by dietary cellulose is greater than the promotive effect of dietary lard as assessed by repeated endoscopic observation.

We developed a method which we used in the current study to observe the rat colon endoscopically. Our goal was to evaluate the entire course in the development of experimental large bowel tumors through serial observations in the same rat. We compared the effects of dietary lard and cellulose on rat colon tumorigenesis in a 2 x 3 factorial design. Sprague-Dawley rats (n = 90) were divided into 6 diet groups: rats were fed a diet without cellulose that contained 5, 10, and 15 g/100 g lard, or diets containing 15% cellulose diet (15 g cellulose/100 g diet) and the same concentrations of lard. The development of large bowel tumors induced by the administration of 1,2-dimethylhydrazine (25 mg/kg body weight) for 19 wk was examined endoscopically. Tumor induction rates in the 15% cellulose groups were lower than in the 0% cellulose groups (P = 0.008), independent of the lard concentration. These results suggest that the preventive effect of cellulose against large bowel tumorigenesis is greater than the promotive effect of fat under the current experimental conditions.

1,2-Dimethylhydrazine↗
PubMed2003

Increase of human MTH1 and decrease of 8-hydroxydeoxyguanosine in leukocyte DNA by acute and chronic exercise in healthy male subjects.

To investigate the effects of exercise on oxidative DNA damage, we measured the levels of 8-hydroxydeoxyguanosine (8-OH-dG, 7,8,dihydro-8-oxo-deoxyguanosine), and mRNA of its sanitization enzyme, human MutT homologue (hMTH1), after mild acute exercise in healthy male subjects. The basal 8-OH-dG levels of physically active subjects were significantly lower than those of sedentary subjects. After mild exercise for 30min, the 8-OH-dG levels of the sedentary subjects significantly decreased. In correspondence with the change of 8-OH-dG levels, the hMTH1 mRNA levels of the physically active subjects were significantly higher than those of the sedentary subjects. The levels of hMTH1 mRNA of sedentary subjects significantly increased after mild exercise. Furthermore, there was a significant negative correlation between the levels of 8-OH-dG and hMTH1 mRNA. These results suggest that a mild exercise has a beneficial effect on the maintenance of low levels of 8-OH-dG probably by keeping the sanitization system at higher levels.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

Inhibitory effect of small amounts of cellulose on colonic carcinogenesis with low-dose carcinogen.

This study set out to evaluate the effects of dietary fiber on cancer development in the large bowel under in vivo experimental conditions as similar as possible to those under which this cancer develops in vivo in humans. Forty-eight Sprague-Dawley rats were divided into three groups that were fed either a nonfiber diet or a 3 g or 10 g/100 g cellulose diet in this experiment, and all groups received doses of a mild carcinogen, 1,2-dimethylhydrazine (5 mg/kg body weight) for 50 weeks. Following endoscopic observation of the large bowel, we found that the induction rates of tumor in the cellulose groups were significantly lower than that in the nonfiber diet group, both endoscopically and histologically. No differences were seen between the 3% and 10% cellulose groups in suppressing carcinogenesis. It is likely that the inhibitory effect of 3% cellulose could be confirmed only by a long-term experiment on carcinogenesis following the administration of a low dose of carcinogen.

Animals↗
PubMed2002

Effects of growth hormone on testicular dysfunction induced by cyclophosphamide (CP) in GH-deficient rats.

Growth hormone (GH) is known to accelerate spermatogenesis and maintain gonadal function. In this study, we evaluated the effect of GH on recovery from testicular damage induced by cyclophosphamide (CP). Eleven- to fourteen-week-old GH-deficient Lewis rats (dw/dw) were divided into 4 groups (n = 10 each), with one group serving as controls. In the CP group, CP was intravenously administered in daily doses of 50 mg/kg for 2 days, followed by daily doses of 10 mg/kg for the next 3 days. In the GH group, rat GH was subcutaneously administered at a daily dose of 0.3 mg/kg until the rats were sacrificed. In the CP/GH group, GH and CP administration were started simultaneously. In the CP/preGH group, GH administration was started 14 days before CP administration. Five rats from each group were sacrificed at days 14 and 28 after administration of CP. Spermatogenesis was then evaluated morphometrically by counting numbers of cells at several stages of the spermatogenic cycle. On day 14, there were no significant differences in the numbers of the spermatocytes between CP and CP/GH group. On day 28, the numbers of spermatocytes and motility of spermatozoa in CP/GH group were greater than those of CP group were. In the CP/preGH group, these effects of GH administration were not observed. These results suggested that administration of GH improved testicular function damaged by CP under GH-deficient condition, when GH and CP administration are started simultaneously.

Animals↗