Alteration of neuromuscular function after a prolonged road cycling race

The aim of this study was to characterize neuromuscular fatigue in knee extensor muscles after a prolonged cycling exercise. During the two days preceding a 140-km race (mean +/- SD duration: 278.2 +/- 24.9 min) and 15 to 30 min after, maximal percutaneous electrical stimulations were applied to the femoral nerve of 11 trained cyclists. Electrically evoked superimposed twitches and trains of 6 stimulations were delivered during isometric maximal voluntary contraction (MVC) to determine maximal voluntary activation (% VA). Knee extensors MVC decreased with fatigue from 158.2 +/- 29.6 to 144.2 +/- 30.0 Nm (p < 0.01), but no central activation failure was detected after the race. The average rate of twitch force development increased significantly from 414 +/- 106 to 466 +/- 102 N x m x s-1 (p < 0.05) and a tendency toward higher peak twitch tension (p = 0.052) was found in the fatigued state. Short tetanus at 20 Hz and 80 Hz were also applied to 4 cyclists, but these fused and unfused tetanic forces were not significantly modified with fatigue. From these results, it can be concluded that the small but significant isometric strength loss measured less than 30 min after the end of a long distance road cycling race is not due to central fatigue. It is also suggested that a raise in peak twitch tension is not necessarily associated with enhanced neuromuscular function.     

Neurological soft-signs and minor physical anomalies in schizophrenia: differential transmission within families

Markers of vulnerability have been identified in schizophrenia, and among them, neurological soft-signs (NSS) and minor physical anomalies (MPAs) also seem to occur in biological relatives. The similarities of these developmental markers within families may depend on either genetic or non-genetic factors. The aim of the study was to investigate the intra-familial similarities of NSS and MPAs within 18 nuclear families (18 probands with schizophrenia and 36 of their non-psychotic parents). A general linear model showed similarities within families for NSS (intra-class coefficient [ICC] = 0.64; F = 2.6; df = 17.17; p = 0.02) but not for MPAs (ICC = -0.10; F = 0.7; df = 17.17; ns). We thus found a direct evidence for the intra-familial transmission of NSS but not of MPAs, suggesting that this morphological phenotypic trait could be more dependent on epigenetic influences.     

Psychosocial influences on weight gain attitudes and behaviors during pregnancy

OBJECTIVE: To examine pregnant women's weight-related attitudes and behaviors in relation to a constellation of psychosocial characteristics, prepregnancy body habitus, and gestational weight gain. PARTICIPANTS: One hundred-thirty women with low-risk, normal pregnancies. DESIGN: Cross-sectional, observational study assessed attitudes about weight gain at 36 weeks' gestation. Psychosocial characteristics, including anxiety, depression, social support, emotionality, and pregnancy-specific and nonspecific stress appraisal were assessed between 28 and 36 weeks' gestation. STATISTICAL ANALYSIS PERFORMED: Principal components factor analysis, Pearson correlations, t tests, and analysis of variance. RESULT: A range of positive and negative attitudes about weight gain was expressed. Twenty-one percent (n=27) of the sample endorsed at least one weight-restrictive behavior during pregnancy. Women who reported more weight-restrictive behaviors were more anxious (r=.24, P<.01), depressed (r=.29,P<.001), angry (r=.29, P<.001), stressed (r=.23, P<.01), and felt less uplifted (r=-.21, P<.05) about their pregnancies in general. Higher Positive Pregnancy Body Image scores were associated with feeling better about the pregnancy in general (r=.35, P<.001), fewer depressive symptoms, and less anger (both r=.20, both P<.01). Women who were self conscious about their weight gain felt more hassled by their pregnancies (r=.21, P<.05), greater anger (r=.21, P<.05), and more support from partners (r=.22, P<.05). Prepregnancy body mass index was unrelated, but negative attitudes about weight gain existed even among women who gained within recommended ranges. CONCLUSION: Women's attitudes about weight gain in pregnancy are imbedded in their orientation toward pregnancy as well as their general psychological functioning. Effective nutrition counseling for pregnant women should include consideration of weight-restrictive behaviors, the degree to which the pregnancy is perceived as positive and uplifting, and whether weight gain attitudes may be associated with their relationship with a spouse or partner.     

Comparison of two hard keratinous substrates submitted to the action of a keratinase using an experimental design

The influence of temperature, pH, keratinase concentration, substrate concentration and incubation time on the soluble proteins released by a new keratinase from Doratomyces microsporus was studied with a second-order experimental design. Only 15 or 18 spectrophotometric analyses were required to determine the optimal experimental conditions for this keratinase on nail and hoof. This study was carried out by measuring, according to Smith's method, the concentration of soluble proteins released by the enzyme on two substrates: nails and sheep hooves. Results give optimum conditions for the keratinase to release the soluble proteins: pH 8.2, keratinase concentration 0.14% (weight of keratinase lyophilisate/final volume) and substrate concentration 5% (weight of nail powder/final volume) for nails; temperature 38.8 degrees C, pH 9, substrate concentration 5% (weight of hoof powder/final volume) and a 5 h 55 min incubation time for hooves.     

Effect of two drafting modalities in cycling on running performance

PURPOSE: The purposes of this study were first to compare the physiological responses during a triathlon where cycling was performed alternatively with another cyclist (alternate draft triathlon, ADT) or continuously behind him (continuous draft triathlon, CDT), and second to study the incidence of these two drafting modalities in cycling on the subsequent running performance done during a simulated triathlon. METHODS: Ten male triathletes of national level performed a sprint distance triathlon (0.75-km swim, 20-km bike, 5-km run) on two different sessions, one where the triathlete alternatively rode in front or at the back of another cyclist and rotating every 500 m, the other where the triathlete drafted continuously a professional cyclist whose task was to reproduce all split times recorded during the alternate situation. Oxygen uptake (VO2), expiratory flow (VE), heart rate (HR) were recorded during the entire bike and run sections and blood lactate concentrations ([La-]b) were analyzed at the end of each event composing the triathlon. RESULTS:The results showed that expiratory flow, oxygen uptake, heart rate and blood lactate concentrations were significantly lower in CDT on the bike compared with drafting in alternation (148.1 vs. 167.2 L.min-1, 49.9 vs. 59.8 mL.min-1.kg-1, 154.7 vs. 173.1 beats.min-1, 3.5 vs. 6.3 mmol.L-1, respectively). The results also revealed that running after biking in CDT (for similar cycling speeds) significantly improved the subsequent running speed compared to ADT (17.87 vs. 17.15 km.h-1). Furthermore, VE, VO2, HR, and [La-]b were significantly higher during CDT run compared with ADT run (175.6 vs. 170.4 L.min-1, 69.7 vs. 66.8 mL.min-1.kg-1, 182.6 vs. 177.3 beats.min-1, 9.6 vs. 7.5 mmol.L-1, respectively). CONCLUSIONS: These results showed that drafting continuously behind a lead cyclist allows triathletes to save a significant amount of energy during the bike leg of a sprint triathlon and creates the conditions for an improved running performance compared with a situation where cycling is performed alternating the lead with another cyclist.     

小鼠脑缺血后的能量代谢改变和药物的作用

应用部分结扎小鼠颈总动脉(包括迷走神经)及小鼠断头法引起脑缺血后,脑组织的ATP和磷酸肌酸明显降低,乳酸明显升高。部分结扎颈动脉出现四肢无力、转圈及昏睡等症状,其严重程度与脑能量代谢改变相平行。皮下注射尼莫地平、硝苯吡啶、尼卡地平和三七皂甙对脑缺血有一定保护作用。苯巴比妥钠能改善正常和脑缺血小鼠的脑能量代谢,人参皂甙Rb₁可降低正常小鼠脑乳酸含量。     

新缩瞳剂包公藤甲素人工合成研究

包公藤甲素是从包公藤(Erycibe obtusifolia Benth.)茎中提得的一个新莨菪烷生物碱,具有强烈的缩瞳作用,临床用于治疗青光眼。本文报道用合成的6β-乙酰氧基托品酮为原料,经卤代、水解、还原和N-去甲基化等反应合成包甲素(8)。经光谱测定证实8与天然包甲素的结构完全一致。合成品系外消旋体,其作用机理与天然品相同,而强度则减半。     

Endocrine responses to 7 days of head-down bed rest and orthostatic tests in men and women.

The objective of this study was to investigate plasma volume (PV), total body water, hormones and hydroelectrolyte responses in eight males (25-40 years) and eight females (25-31 years) during 7 days of exposure to simulated microgravity (-6 degrees head-down bed rest, HDBR). Bed rest is a model that has commonly been used to simulate spaceflight. Heart rate (HR), blood pressure (BP) and vasoactive hormone responses were studied before and after HDBR during a 10-min stand test. No change in total body water and body mass was noted in either sex. The decrease in PV was similar in both men (9.1 +/- 1.4%) and women (9.4 +/- 0.8%). Urinary normetanephrine (NMN) was decreased during HDBR in both sexes. Urinary metanephrine (MN) and plasma catecholamines were unchanged. Daily urinary excretion of urea, an indirect index of protein breakdown, was increased only in the female subjects during HDBR. Plasma active renin (AR) and aldosterone were increased in both sexes, but urinary atrial natriuretic peptide (ANP) and arginine vasopressin (AVP) were unchanged throughout the study. Also, the hormonal responses to 7 days of HDBR were comparable between men and women. Moreover, the results show similar cardiovascular and endocrine responses to standing after HDBR. However, the orthostatic intolerance following HDBR was associated with a blunted increase in noradrenaline (NA) only in the women during the stand test. It is concluded that: (i) 7 days of physical inactivity achieved during HDBR resulted in a reduced sympathetic activity in both sexes and alterations in protein metabolism in women and (ii) standing after HDBR resulted in an attenuated release of noradrenaline in women.