Irgm1 knockout indirectly inhibits regeneration after skeletal muscle injury in mice

Immunity-related GTPase family M1 protein (lRGM1) plays an important role in host resistance to infection, immune inflammation, and tumors, and it is expressed in various tissues and cells, including the central nervous system, cardiovascular system, bone marrow-derived cells, glioma, and melanoma. However, the effect of IRGM1 in the muscles has not been reported to date. In this study, Irgm1^−/− mice were used to evaluate the effect of lrgm1 on regeneration after skeletal muscle injury. The tibialis anterior muscle in Irgm1^−/− mice was poorly repaired after BaCl₂-induced injury, whereas lrgm1 knockout itself had no significant effect on the differentiation of myoblasts. However, the microenvironment of Irgm1^−/− mice with a high interferon-gamma level inhibited the differentiation of myoblasts in vivo. These results suggest that lrgm1 knockout indirectly inhibits skeletal muscle regeneration after injury, providing new insights into the biological function of IRGM1.     

中等强度训练干预大鼠骨骼肌抗增殖蛋白PHB1表达及线粒体呼吸功能的变化

背景:研究显示长期中等强度规律运动可以改善骨骼肌细胞线粒体电子呼吸链复合体酶的活性,从而提高其做功能力和抵抗疲劳能力。目的:探讨中等强度训练对大鼠骨骼肌内抗增殖蛋白及线粒体呼吸功能的影响。方法:32只健康雄性SD大鼠随机分为2组:安静对照组、中等强度训练组,每组16只。中等强度训练组的训练方案:第1周以10 m/min速度跑,每周6 d,每天10 min,坡度10°;第2周以15 m/min速度跑,每周6 d,每天增加10 min至60 min结束,坡度10°;第3-8周以15 m/min速度跑,每周6 d,每天60 min,坡度10°。末次实验后48 h处死大鼠,提取骨骼肌以及线粒体,检测线粒体呼吸控制率、ATP含量、活性氧水平、复合体V活性及PHB1蛋白表达。结果与结论:①与安静对照组相比,中等强度训练组骨骼肌线粒体呼吸控制率显著性升高(P<0.001)、ATP含量显著性升高(P<0.05)、活性氧水平显著降低(P<0.001)、复合体V活性显著升高(P<0.05)、PHB1表达显著升高(P<0.01);②通过相关性分析得出:经过8周中等强度训练后大鼠骨骼肌内PHB1的表达分别与ATP含量、复合体V活性呈正相关,与活性氧水平呈负相关;③结果表明,中等强度训练通过促进PHB1表达提高线粒体氧化磷酸化功能,维持线粒体膜结构,增强线粒体呼吸功能。     

不同骨密度老年人群的体成分、肌力及心脏功能特点

目的 分析不同骨密度老年人群的体成分、肌力和心脏功能特点。方法 选择2019年1月至2021年12月在内蒙古自治区人民医院健康管理中心行骨密度检查年龄为65~80岁的500名受试者作为研究对象。采用人体成分分析仪检测并记录受试者骨骼肌指数、体脂肪率、脂肪控制、肌肉控制、右臂肌肉量、肌力；采用超声诊断仪检查并记录受试者心脏功能（EF、EDV、ESV、FS、HR、e/a）。结果 在500例研究对象中，骨量异常人数较多，占77 %，其中骨质疏松者93人（18.6 %），骨量减少者292人（58.4 %），骨量正常者115人（23%）。在男性中，骨质疏松者21人（8.4 %），骨量减少者153人（61.2 %），骨量正常者76人（30.4 %）；在女性中，骨质疏松者72人（28.8 %），骨量减少者139人（55.6 %），骨量正常者39人（15.6 %）；女性患骨质疏松的比例高于男性。女性的体脂肪率（37.20±4.13）高于男性（28.15±5.38）；女性骨骼肌指数（8.20±0.58）低于男性（9.23±0.55）（P＜0.05）。500例研究对象中需进行肌肉控制（增肌）的比例为55.6 % (278人),需进行脂肪控制（减脂）的比例为100 %（500人）。男性、女性分别按照骨密度分为骨质疏松组、骨量减少组及骨质正常组，三组体质量指数（body mass index, BMI)、T值、 Z值、骨骼肌指数、肌肉控制、右臂肌肉量、右手握力、左手握力比较，差异有统计学意义（P＜0.05）；年龄、体脂肪率、脂肪控制比较，差异无统计学意义（P＞0.05）。组间两两比较男性组BMI、T值、 Z值、骨骼肌指数、肌肉控制、右臂肌肉量、右手握力、左手握力组间比较差异有统计学意义（P＜0.05）；女性组T值、 Z值、骨骼肌指数、肌肉控制、右臂肌肉量、右手握力、左手握力组间比较差异有统计学意义（P＜0.05）。Pearson 相关分析显示，T值与骨骼肌指数、BMI、右臂肌肉量及右手握力呈正相关；相较BMI，T值与骨骼肌指数、右臂肌肉量相关性更高；与肌肉控制（增肌）呈负相关（r值= – 0.326，P=0.000）；与体脂肪率及脂肪控制无相关性。心脏功能EDV（F=0.042,P=0.958）、ESV（F=0.008,P=0.992）、EF值（F=0.060,P=0.942）、FS值（F=0. 057,P=0.945）、HR（F=0. 032,P=0.969）组间比较差异无统计学意义（P＞0.05）；e/a（F=3.768,P=0.034）比较差异有统计学意义（P＜0.05）。结论 老年人群骨量异常比率较高，随着骨密度减低，骨骼肌指数及肌力也会下降，且骨质疏松患者易出现心脏舒张功能减低。利用生物电阻抗测定人体成分可以分析骨质疏松患者人体成分变化，能够更细化地了解其肌肉和脂肪的含量，为进一步预防、治疗骨质疏松及优化老年人人体成分提供依据。     

Mechanical and morphological determinants of peak power output in elite cyclists

Mechanical peak power output (PPO) is a determinant of performance in sprint cycling. The purpose of this study was to examine the relationship between PPO and putative physiological determinants of PPO in elite cyclists, and to compare sprint performance between elite sprint and endurance cyclists. Thirty-five elite cyclists (18 endurance; 17 sprint) performed duplicate sprint cycling laboratory tests to establish PPO and its mechanical components. Quadriceps femoris (Q_VOL) and hamstring muscle volume (HAM_VOL) were assessed with MRI, vastus lateralis pennation angle (Pθ_VL) and fascicle length (FL_VL) were determined with ultrasound imaging, and neuromuscular activation of three muscles was assessed using EMG at PPO during sprint cycling. For the whole cohort, there was a wide variability in PPO (range 775-2025 W) with very large, positive, bivariate relationships between PPO and Q_VOL (r = .87), HAM_VOL (r = .71), and Pθ_VL (r = .81). Step-wise multiple regression analysis revealed that 87% of the variability in PPO between cyclists was explained by two variables Q_VOL (76%) and Pθ_VL (11%). The sprint cyclists had greater PPO (+61%; P < .001 vs endurance), larger Q_VOL (P < .001), and BF_VOL (P < .001) as well as more pennate vastus lateralis muscles (P < .001). These findings emphasize the importance of quadriceps muscle morphology for sprint cycling events.     

Changes in urinary titin N-terminal fragments as a biomarker of exercise-induced muscle damage in the repeated bout effect

ObjectivesMuscle damage symptoms induced by unaccustomed eccentric contraction exercise can be reduced by repeating the experience several times. This phenomenon is termed the repeated bout effect. Although traditional biochemical markers require invasive blood sampling, biochemical measurements have recently been developed that can be non-invasively performed using urinary titin N-terminal fragment (UTF). However, it is unclear whether UTF can reflect the repeated bout effect. Therefore, the aim of the present study was to clarify whether UTF decreased with the repeated bout effect.DesignThis study compared changes in muscle damage markers between bouts of exercise performed for the first and second time.MethodsEight young men performed 30 eccentric exercises of the elbow flexor on the first day of the first week (Bout 1). A second bout of eccentric exercises, same as the first, was performed 2 weeks later, (Bout 2). The dependent variables were muscle soreness (SOR), maximal voluntary isometric contraction (MVIC), range of motion (ROM), creatine kinase (CK), and UTF. All dependent variables were analyzed using two-way analysis of variance.ResultsNo significant difference was observed in workload or peak torque between the first and second exercise bouts. SOR as well as CK and UTF were significantly lower and ROM and MVIC were significantly higher in Bout 2 in comparison to Bout 1.ConclusionsThese results suggest that UTF sensitively reflects the repeated bout effect and exercise-induced muscle damage can be non-invasively measured.     

生物反馈电刺激联合补中益气汤对产妇产后盆底康复效果的影响

目的探讨生物反馈电刺激联合补中益气汤对产妇产后盆底康复效果的影响。方法将56例初产妇按随机数字表法分成对照组与研究组各28例。对照组给予补中益气汤治疗;研究组在对照组基础上联合生物反馈电刺激治疗,两组均治疗6周。观测盆底肌相关电压、盆底肌力、尿失禁率、性生活质量。结果治疗后,两组盆底电位均值均显著升高,研究组高于对照组(P<0.05);治疗后,研究组尿失禁发生率显著降低,且显著低于对照组(P<0.05);研究组Ⅱ、Ⅲ、IV级肌力显著低于对照组(P<0.05);研究组性生活质量高水平显著高于对照组(P<0.05)。结论生物反馈电刺激联合补中益气汤可有效促进产妇产后盆底康复,效果显著优于单独补中益气汤。