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Influence of CO2 pneumoperitoneum on intracellular pH and signal transduction in cancer cells 总被引：17，自引：0，他引：17
Object: The authors studied the influence of CO2 pneumoperitoneum on intracellular pH and signal transduction arising from cancer cell multiplication in laparoscopic tumor operation. Method: They set up a simulation of pneumoperitoneum under different CO2 pressure, and then measured the variation of intracellular pH (pHi) at different time and the activity of protein kinase C (PKC) and protein phosphatase 2a (PP2a) at the end of the pneumoperitoneum. After 1 week, the concentration of cancer cells in the culture medium was calculated. Result: When the pressure of CO2 pneumoperitoneum was 0, 10, 20, 30 mmHg respectively, the average pHi was 7.273, 7.075, 6.783, 6.693 at the end of the pneumoperitoneum; PKC activity was 159.4, 168.5, 178.0, 181.6 nmol/(g-min) and PP2a was 4158.3,4066.9, 3984.0, 3878.5 nmol/(g-min) respectively. After 1 week, the cancer cells concentration was 2.15×105, 2.03×105, 2.20×105, 2.18×105 L-1. Conclusion: CO2 pneumoperitoneum could promote acidosis in cancer cells, inducing the activation of protein kinase C and deactivation of protein phosphatase 2a, but it could not accelerate the mitosis rate of the cancer cells. 相似文献
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Protein and hordein fraction content in barley seeds as affected by sowing date and their relations to malting quality 总被引：1，自引：0，他引：1
Qi JC Chen JX Wang JM Wu FB Cao LP Zhang GP 《Journal of Zhejiang University. Science. B》2005,6(11):1069-1075
INTRODUCTION Barley (Hordeum vulgare L.) is widely used as food and feed, but its most economically important use is for malting and brewing. Many barley charac- ters are involved in malt quality, of which protein content is the most important, as it has been observed to be related to malt qualities, such as extract and diastatic power (Weston et al., 1993; Eagles et al., 1995).Barley suitable for malting should have low grain protein content, as high protein content will not only reduce… 相似文献
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The relative length of the second and fourth digits (2D:4D) is a putative marker for prenatal testosterone. Low 2D:4D has been reported to correlate with high performance in sport in general. Here, for the first time, we examine the relationship between 2D:4D and performance in elite rugby players. The 44 players (28 forwards, 16 backs) were drawn from the Ospreys Rugby Union Club and 44 age-matched controls. The measures of performance comprised age-adjusted number of international performances (caps) for Wales, a comparison of coaches' first-choice League team with others, and the number of tries scored by backs in club matches. Compared with controls, players were larger and had lower 2D:4D for the right and left hand. With regard to number of caps, players with low 2D:4D in their right hand and low right 2D:4D compared with their left (right?-?left 2D:4D difference) had high numbers of caps. First-choice players did not differ significantly from second-choice players in their 2D:4D but they did have a lower right?-?left 2D:4D difference than second-choice players. Low right 2D:4D and low right?-?left 2D:4D difference were significantly linked with large numbers of tries. We conclude that low right 2D:4D and low right?-?left 2D:4D difference are predictors of high rugby performance. 相似文献
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West DJ Stephens JW Bain SC Kilduff LP Luzio S Still R Bracken RM 《Journal of sports sciences》2011,29(3):279-289
In this study, we examined the glycaemic and fuel oxidation responses to alterations in the timing of a low glycaemic index carbohydrate and 75% reduced insulin dose, prior to running, in type 1 diabetes individuals. After carbohydrate (75 g isomaltulose) and insulin administration, the seven participants rested for 30 min, 60 min, 90 min or 120 min (conditions 30MIN, 60MIN, 90MIN, and 120MIN, respectively) before completing 45 min of running at 70% peak oxygen uptake. Carbohydrate and lipid oxidation rates were monitored during exercise and blood glucose and insulin were measured before and for 3 h after exercise. Data were analysed using repeated-measures analysis of variance. Pre-exercise blood glucose concentrations were lower for 30MIN compared with 120MIN (P < 0.05), but insulin concentrations were similar. Exercising carbohydrate and lipid oxidation rates were lower and greater, respectively, for 30MIN compared with 120MIN (P < 0.05). The drop in blood glucose during exercise was less for 30MIN (3.7 mmol · l(-1), s(x) = 0.4) compared with 120MIN (6.4 mmol · l(-1), s(x) = 0.3) (P = 0.02). For 60 min post-exercise, blood glucose concentrations were higher for 30MIN compared with 120MIN (P < 0.05). There were no cases of hypoglycaemia in the 30MIN condition, one case in the 60MIN condition, two in the 90MIN condition, and five in the 120MIN condition. In conclusion, a low glycaemic index carbohydrate and reduced insulin dose administered 30 min before running improves pre- and post-exercise blood glucose responses in type 1 diabetes. 相似文献
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Kingsley M James N Kilduff LP Dietzig RE Dietzig B 《Journal of sports sciences》2006,24(12):1291-1296
Squash is a popular racket sport that requires intermittent activity with frequent bursts of near maximal-intensity exercise. Consequently, effective physiological and thermoregulatory responses are important contributors to performance during squash match-play. Controlled field-based simulation protocols have been introduced in a growing number of sports, which allow sports scientists to investigate changes in physiology and the efficacy of various interventions in sport-specific contexts. This study aimed to develop an exercise protocol that simulates the physiological requirements of elite squash match-play. Eight elite junior squash players (age 16.2+/-0.8 years, height 1.76+/-0.06 m, body mass 61.3+/-5.9 kg; mean+/-s) completed the following in a randomized order: (1) a squash match against a player of similar standard and (2) a squash-specific incremental exercise protocol (multistage squash test [MST]) followed by the squash simulation protocol (SSP). The multistage squash test was continued for 18.0+/-1.0 min and elicited near maximal post-MST heart rates, blood lactate concentrations and ratings of perceived exertion (198+/-9 beats.min-1, 5.7+/-1.7 mmol.l-1 and 18+/-1, respectively). The SSP was 12.2 min in length compared with mean game length during competitive matches of 10.0+/-1.6 min (P=0.27). Peak heart rates were similar during the SSP and match-play (192+/-11 and 189+/-6 beats.min-1, respectively; P=0.44). Mean exercising heart rates were similar during the SSP (180+/-8 beats.min-1) and match-play (179+/-13 beats.min-1; P=0.73). Peak blood lactate concentrations during the SSP and match-play were 3.5+/-1.5 and 2.4+/-1.2 mmol.l-1 (P=0.07), respectively. Peak ratings of perceived exertion during the SSP and match-play were similar (17+/-2 and 17+/-2, respectively; P=0.64). It was concluded that the SSP closely replicated the demands of squash match-play in elite junior squash players. Furthermore, the SSP provides coaches and scientific support staff with a controlled squash-specific exercise protocol that has potential application in the objective investigation of a range of interventions such as training programmes, nutritional supplements and strategies to maintain core body temperature. 相似文献
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Hadjicharalambous M Georgiades E Kilduff LP Turner AP Tsofliou F Pitsiladis YP 《Journal of sports sciences》2006,24(8):875-887
This study examined the effects of caffeine, co-ingested with a high fat meal, on perceptual and metabolic responses during incremental (Experiment 1) and endurance (Experiment 2) exercise performance. Trained participants performed three constant-load cycling tests at approximately 73% of maximal oxygen uptake (VO2max) for 30 min at 20 degrees C (Experiment 1, n = 8) and to the limit of tolerance at 10 degrees C (Experiment 2, n = 10). The 30 min constant-load exercise in Experiment 1 was followed by incremental exercise (15 W . min-1) to fatigue. Four hours before the first test, the participants consumed a 90% carbohydrate meal (control trial); in the remaining two tests, the participants consumed a 90% fat meal with (fat + caffeine trial) and without (fat-only trial) caffeine. Caffeine and placebo were randomly assigned and ingested 1 h before exercise. In both experiments, ratings of perceived leg exertion were significantly lower during the fat + caffeine than fat-only trial (Experiment 1: P < 0.001; Experiment 2: P < 0.01). Ratings of perceived breathlessness were significantly lower in Experiment 1 (P < 0.01) and heart rate higher in Experiment 2 (P < 0.001) on the fat + caffeine than fat-only trial. In the two experiments, oxygen uptake, ventilation, blood [glucose], [lactate] and plasma [glycerol] were significantly higher on the fat + caffeine than fat-only trial. In Experiment 2, plasma [free fatty acids], blood [pyruvate] and the [lactate]:[pyruvate] ratio were significantly higher on the fat + caffeine than fat-only trial. Time to exhaustion during incremental exercise (Experiment 1: control: 4.9, s = 1.8 min; fat-only: 5.0, s = 2.2 min; fat + caffeine: 5.0, s = 2.2 min; P > 0.05) and constant-load exercise (Experiment 2: control: 116 (88 - 145) min; fat-only: 122 (96 - 144) min; fat + caffeine: 127 (107 - 176) min; P > 0.05) was not different between the fat-only and fat + caffeine trials. In conclusion, while a number of metabolic responses were increased during exercise after caffeine ingestion, perception of effort was reduced and this may be attributed to the direct stimulatory effect of caffeine on the central nervous system. However, this caffeine-induced reduction in effort perception did not improve exercise performance. 相似文献
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DaCosta LP 《国际体育史杂志》2001,18(3):181-196
This epilogue offers a critical overview of some current interpretations of modern sport's origins and evolution in Latin America by certain European and North American commentators. These analyses still adhere to the tradition of the New World's creation. They seldom refer to primary sources. Conclusions are often born out of patronizing compassion and exotic impression. Latin American sources, if any, are mostly quoted when they serve a pessimistic historical bias cultivated by outsiders. In fact, Latin American sport represents a mirror image of more developed areas and indeed a reinvention of sport in specific cases of community isolation and self-development. 相似文献
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