Yohko Sugawa-Katayama

Effect of repeated exercise on urinary 8-hydroxy-deoxyguanosine excretion in humans.

The purpose of this study was to investigate the effect of repeated exercise on oxidative damage to DNA in 10 well trained long distance runners who participated in an 8-day training camp. The average running distance during the camp was 30 +/- 3 km/day. The amount of urinary 8-hydroxy-deoxyguanosine (8-OHdG) excretion was used to estimate the oxidative DNA damage. Urine samples were collected for both a 3-day control period as well as throughout the camp. Blood samples were drawn after overnight fasting both before and after the camp. Urinary 8-OHdG excretion was significantly increased during the camp compared to the control period (265.7 +/- 75.5 vs. 335.6 +/- 107.4 pmol/kg/day, P < 0.05). The content of 8-OHdG in the lymphocyte DNA on the day after finishing the camp did not differ from that before the camp. Plasma TBARS, LDH, CK, CK-MB, and myoglobin significantly rose after the camp (P < 0.05). The plasma beta-carotene levels tended to rise after the camp, while the plasma alpha-tocopherol levels increased significantly after the camp (P < 0.05). These results indicate that repeated exercise augments oxidative stress and the DNA is also injured by exercise-induced reactive oxygen species. However, the oxidative damage to DNA is not accumulated by consecutive exercise, although it is sustained as long as the exercise is repeated.

No influence of a single bout of exercise on urinary excretion of 8‐hydroxy‐deoxyguanosine in humans

We investigated the effect of a single bout of intensive exercise on the excretion of 8‐hydroxy‐deoxyguanosine in the 24 h urine from healthy non‐smokers. We studied three exercise tests in Experiment 1; which consisted of incremental exercise to exhaustion on a treadmill in eleven male long distance runners. Experiment 2; which comprised incremental exercise until reaching exhaustion on abicycle ergometer in six male untrained subjects. Experiment 3; which consisted of a 20 km run by eleven male long distance runners. No differences in the urinary 8‐hydroxy‐deoxyguanosine excretion were obselwed from days 1 or 3 after each respective exercise regimen. However, significant increases in the plasma creatine kinase activity were observed at 24 h or 48 h after exercise, except for Experiment 2. Our results thus suggest that the oxidative stress during a single bout of intensive exercise does not result in an accumulation of oxidative DNA damage.

Effect of endurance exercise on the tissue 8-hydroxy-deoxyguanosine content in dogs.

The purpose of this study was to investigate the effect of endurance exercise on both the tissue and lymphocyte 8-hydroxy-deoxyguanosine (8-OHdG) content. Six dogs ran on a treadmill for 7 hours. Another six dogs were assigned to a sedentary control group. The exercised dogs were sacrificed immediately after exercise and the counterpart of the sedentary group was also sacrificed at the same time. The brain, lung, liver, spleen, kidney, jejunum, colon, diaphragm, heart, splenius muscle, and the medial and lateral portion of gastrocnemius muscle samples were then collected. Lymphocytes were sampled before and after exercise in the exercised dogs. The 8-OHdG content of lymphocyte DNA was found to significantly decrease after exercise (0.57 +/- 0.19 vs 0.33 +/- 0.10/deoxyguanosine (dG) x 10(5), P < 0.05). The colon was the only tissue which showed a significant decrease in the content (0.83 +/- 0.24 vs 0.54 +/- 0.15/dG x 10(5), P < 0.05). No tissue except for the colon showed any significant changes after exercise. These results therefore indicate that, immediately after endurance exercise, an augmented repair mechanism might thus play a role in the decrease of 8-OHdG in the lymphocytes and the colon, while the 8-OHdG generation might be counterbalanced by its repair in other tissues.

Effects of partially hydrolyzed guar gum on the morphological surface structure of intestinal mucosa in the rat

Publisher Summary This chapter examines the effects of partially hydrolyzed guar gum on the morphological fine structure of intestinal mucosa in rats through a series of investigations. The Sprague-Dawley male rats are fed a diet containing 5% partially hydrolyzed guar gum (experimental diet) for four weeks. A significant increment in the weight of the cecum and in its contents, and a significant decrement in the fecal weight are observed while comparing the rats with those which are fed a 5% cellulose diet (control diet). The transit time of the gastrointestinal tract is extended by the partially hydrolyzed guar gum supplementation. The surface structures of ileal and cecal mucosa change markedly to the abnormal ones among those which are fed the experimental diet; their microvilli of the experimental diet group are more tightly packed than those of the controlled, and more intestinal contents adhere to the tops of the microvilli in the experimental diet group. When rats are fed a diet containing 1% partially hydrolyzed guar gum together with 4% cellulose, the effects of the partially hydrolyzed guar gum are significantly reduced. In conclusion, an excess of a partially hydrolyzed guar gum exerts effects on the ileal and cecal mucosal surface structure.

Fructose Transport in Small Intestinal Mucosa

小腸のeverted sacにおける果糖の輸送が白ネズミを高果糖食で飼育した場合に増大することを観察した。1) 5週齢のSprague Dawley系雌白ネズミを高果糖食または高ブドウ糖食で2週間meal-feeding (9時～12時) した。2) 小腸のeverted sacを作製し, 反応液中に1mM果糖, 20mM NaFを加えて37℃でincubationし, everted sacへの果糖のとりこみを経時的に測定した。3) everted sacへの果糖のとりこみは, 高果糖食で飼育された白ネズミでは高ブドウ糖食のものよりも大きい値を示した。4) NaFの添加によってeverted sac中のATPase活性が高果糖食群では低下した。とくにNa+, K+-ATPaseの低下が著しかった。5) 反応液に2, 4-dinitrophenolを添加すると, everted sacへの果糖のとりこみが減少した。