不同负荷运动训练对大鼠骨骼肌线粒体三羧酸循环的影响及其机制研究

目的：探讨不同负荷运动训练对大鼠骨骼肌线粒体三羧酸循环的影响及其机制。方法：将雄性Wistar大鼠50只随机均分为5组：安静对照组（C）、低负荷运动训练组（LT）、中等负荷运动训练组（MT）、高负荷运动训练组（HT）和极高负荷运动训练组（ST），每组10只。各运动组分别进行6周的跑台运动训练。训练方案结束后，取腓肠肌样本，提取线粒体，测定线粒体柠檬酸合成酶（CS）、异柠檬酸脱氢酶（ICD）和α-酮戊二酸脱氢酶（α-KGDHC）活性；线粒体Ga²⁺含量、胞浆NADH、NAD⁺、ATP和ADP含量，以及ICD mRNA转录水平。结果：（1）不同负荷运动训练组线粒体CS、ICD和α-KGDHC的活性均显著高于安静对照组（P < 0.01），且CS和ICD活性由高到低顺序均为：MT组 > HT组 > ST组 > LT组 > C组，α-KGDHC活性由高到低顺序为：HT组 > MT组 > ST组 > LT组 > C组。（2）不同负荷运动训练组线粒体Ca²⁺ 含量均显著高于安静对照组（P < 0.01），其含量由高到低顺序为：MT组 > HT组 > ST组 > LT组 > C组；胞浆NADH/NAD⁺和ATP/ADP的比值均显著低于安静对照组（P < 0.01），其比值由低到高顺序为：MT组 < ST组 < HT组 < LT组 < C组。（3）不同负荷运动训练组ICD mRNA转录水平均高于安静对照组（P < 0.01），其水平由高到低顺序为： MT组 > HT组 > ST组 > LT组 > C组。结论：低负荷、中等负荷、高负荷及极高负荷运动训练均可提高大鼠骨骼肌线粒体三羧酸循环功能，且中等负荷运动训练效果最佳。其机制与胞浆NADH/NAD⁺和ATP/ADP比值、线粒体摄钙能力及限速酶基因的表达有关。     

体育运动中神经-肌肉疲劳研究的新进展

简要回顾神经-肌肉疲劳的研究历史,并从生理学角度综述近年来国内外有关中枢性疲劳与外周疲劳的理论研究成果以及在实验研究方面取得的新进展.有关中枢性疲劳,着重介绍5-羟色胺、多巴胺、乙酰胆碱等中枢神经递质参与运动性疲劳的形成与恢复的新证据与新理论(可能的机制).有关外周疲劳机制,从神经肌肉接头处的超微结构到骨骼肌细胞的亚细胞结构等可能发生疲劳的部位,将近年来的研究成果作简要概括.这些研究成果表明有关运动性疲劳的生理学研究进入到亚细胞水平与分子水平.     

人体运动图像边缘处理

根据人体运动图像的特点，引用图像层的平滑处理和图像层的边缘处理获得了较好的人体运动边缘图像，通过轮廓跟踪能较好地提取了人体运动图像边缘，为研究人体运动图像质心定位作好了准备。同时也为处理人体运动图像提供了一种新的方法。     

骨骼肌基因转移系统的建立

以EGFP为标记基因，利用重新构建的pAV-EGFP质粒，采用直接注射方法，进行了离体和在体基因转移研究。实验结果显示，经脂质体包裹后，质粒可以有效地进行细胞转移；DNA表达载体肌肉直接注射后，利用共聚焦显微镜可以在注射点周围的肌细胞观察到绿色荧光蛋白；而在对侧肢PCR和共聚焦显微镜的结果均为阴性。实验结果表明，肌肉直接注射DNA可以在肌肉得到表达，将会为治疗肌肉损伤带来新的方法。     

低氧训练促进大鼠骨骼肌组织血管生成的体视学研究

为了研究低氧、训练及低氧训练对骨骼肌组织血管生成的不同作用,采用3×3析因设计试验,将健康雄性SD大鼠72只,随机分为9组,采用免疫组织化学及生物体视学方法,检测骨骼肌组织中微血管密度参数的改变,分析低氧和运动训练两种不同的处理因素对骨骼肌组织微血管体积密度、表面积密度、长度密度的单独效应、主效应及交互作用.结果表明:CD34可较好显示骨骼肌组织的微血管.低氧处理及运动训练对骨骼肌组织微血管体积密度、表面积密度、长度密度的主效应有差别,低氧处理、运动训练的单独效应中以超低氧处理、低氧训练的效应最强,并且低氧处理与训练方式两因素之间具有协同交互作用.     

力竭运动对小鼠骨骼肌6种元素含量的影响

利用高频电感耦合等离子体原子发射光谱法(ICP-PES)测定了小鼠一次性力竭游泳运动后，骨骼肌内铁(Fe)、锌(Zn)、铜(Cu)、硒(Se)、钙(Ca)、镁(Mg)6种元素含量的变化。结果表明，力竭运动后可使小鼠骨骼肌内Ca、Se含量明显上升，Cu元素含量基本不变，Fe、Zn、Mg含量则明显下降。为进一步研究运动员大运动量训练后合理补充微量元素提供科学的依据。     

针刺和静力牵张对大负荷运动后骨骼肌M线变化影响的免疫电镜研究

用胶体金标记技术定位运动后及运动后经针刺或静力牵张处理的人骨骼肌M蛋白,以探讨超过习惯负荷后骨骼肌收缩结构变化以及针刺和静力牵张对促进其恢复的机制。我们发现:大负荷斜蹲后未经针刺的对照腿股外肌M线的M蛋白标记密度低于针刺腿(P<0.05),而对照腿M线两侧及M线两侧以外的M蛋白标记密度高于针刺腿(P<0.05)。对照实验证明运动腿M线以外增加的标记物为物异性标记。静力牵张组在M线及M线两侧的标记结果与针刺组一致。仅在M线两侧以外区域牵张腿与运动对照腿之间标记密度的差异没有统计学意义。我们还观察到运动后对照腿变化M线体密度达42—48％,而针刺或牵张腿为6—9％。上述结果表明大负荷运动加强了负荷后骨骼肌M蛋白的解聚或降解,从而导致M线结构改变;针刺和静力牵张可显著促进M蛋白的合成或抑制其降解,而使M线结构恢复或稳定。本文还探讨了M线变化与肌粗丝结构变化的关系。     

Socioeconomic segregation between and within curriculum tracking

Previous studies have documented social segregation for single types of tracking, but little previous research has compared levels of segregation across different institutional tracking arrangements. This paper uses extensive administrative data of the Chilean educational system to estimate the magnitude and evolution of socioeconomic segregation between- and within-school curriculum tracking. Results indicate that the unequal distribution of students by socioeconomic status between tracks narrows when tracking takes place within schools, mainly in the presence of market incentives that lead schools to focus on particular student populations.     

Reliability of arterial spin labelling measurements of perfusion within the quadriceps during steady-state exercise

Arterial spin labelling (ASL) provides a potential method to non-invasively determine muscle blood flow and examine the impact of interventions such as supplementation and training. However, it's a method with intrinsically low signal, leading to limitations in accuracy and temporal resolution. To examine these limitations, the current study measured perfusion via ASL on three occasions in the rectus femoris of 10 healthy adults, during light and moderate exercise, over three different exercise durations. For data sampled over 9 min, light intensity exercise gave an average perfusion of 35.0 ± 5.1 ml/min.100g^?1 with a coefficient of variation (COV) of 16% and single intraclass correlation coefficient (ICC) of 0.67. For the moderate bout, perfusion was 51.3 ± 5.6 ml/min.100g^?1 (COV 10%, ICC 0.82). When the same data were analyzed over 5 min 24 s, perfusion was 37.8 ± 11.13 (COV 30%, ICC 0.13) during light and 49.5 ± 8.8 ml/min.100g^?1 (COV 18%, ICC 0.52) during moderate exercise. When sampling was reduced to 1 min 48 s, perfusion was 41.2 ± 13.7 (COV 33%, ICC 0.26) during light and 49.5 ± 13.6 ml/min.100g^?1 (COV 28%, ICC 0.04) during moderate exercise. For 9 min a significant perfusion difference was found between the exercise intensities; however, this was not the case for sampling over 5 min 24 s or 1 min 48 s. Such findings illustrate the potential of ASL to non-invasively monitor muscle perfusion under steady-state conditions, but highlight that extended exercise protocols are necessary in order to generate date of sufficient reliability to be able to discriminate intervention dependent perfusion differences.     

Validity of Self-Reported Pedometer Steps per Day in College Students

The purpose of this article was to examine the validity of self-reported pedometer steps/day. Forty-seven participants were provided a New Lifestyles NL-2000 (NL-2000; Lees Summit, MO, USA) pedometer and a physical activity (PA) diary for 3 weeks, but not informed of the data-storing capabilities. For weeks 2 and 3, each participant was given a step goal of 3,000 steps/day above week 1 average. A 2 × 3 repeated measures analysis of variance (ANOVA) was used to examine differences between reported steps/day. Bland–Altman plots assessed the mean bias and limits of agreement between reporting methods. Mean self-reported and NL-2000 steps/day were 9,264 ± 3,555 and 8,971 ± 3,590 steps/day (n = 26, p > .05). Mean biases were 216 ± 1,753 (week 1), –506 ± 1,355 (week 2), and –590 ± 1,360 (week 3) steps/day. Negative mean bias values indicate higher self-reported steps/day. Mean steps/day were similar between recording methods, but large differences were observed among individuals, suggesting self-reported steps/day may be valid for PA research at the population level, but not the individual level.