高频振动对尾部悬吊大鼠比目鱼肌梭内、外肌纤维肌球蛋白重链表达的影响

目的 观察高频正统波振动对尾部悬吊大鼠比目鱼肌（SOL）梭内、外肌纤维MHC表达的影响。方法 采用大鼠尾部悬吊法建立模拟失重模型,高频正弦波振动大鼠比目鱼肌。用免疫组织化学技术,观察大鼠比目鱼肌（SOL）梭内、外肌纤维MHC表达变化。结果 尾部悬吊7d后大鼠比目鱼肌梭内、外肌纤维中快缩型MHC的表达均有所增加,而在另尾期间给予高频正弦波振动比目鱼肌后梭内、外肌快缩型MHC表达没有明显变化。结论 高频正弦波振动尾部悬吊大鼠比目鱼肌梭内、外肌纤维MHC表型转化有明显的对抗作用。     

低氧引起大鼠心室肌肌球蛋白重链图谱的变化

模拟5000米海拔高度低氧对大鼠心室肌肌球蛋白重链图谱的影响已作研究。用PP/PAGE,心室肌显示3种同功肌球蛋白,即V_1、V_2和V_3。在幼鼠中,V_1占优势,随着年龄的增长,V_3含量逐渐增加。用SDS/PAGE肌球蛋白呈双带、即MHCa和MHCβ,比较低氧与常氧条件下大鼠的心室肌MHCα与MHCβ的相对含量,我们发现低氧适应引起大鼠心室肌肌球蛋白重链图谱的变化,MHCα下降,MHCβ上升;MH邻的增加程度,右心室肌高于左心室。这提示低氧可能激活大鼠心肌编码肌球蛋白β重链的基因。     

山东地方绵羊MHC-DRB3基因PCR-RFLPs反应体系的优化

本文探讨了影响山东地方绵羊MHC—DRB3基因PCR-RFLPs扩增的因素,实验结果表明：抗凝剂、模板的浓度、纯度、Mg^2 的浓度、引物的浓度、变性温度、Taq聚合酶、退火温度等因素对扩增结果的影响,为此我们对影响扩增结果的各个因素和反应程序进行了研究和浓度梯度的对比试验,建立了绵羊MHC—DRB3基因PCR—RFLPs的最佳反应体系和反应程序。     

牛主要组织相容性复合体的研究

主要组织相容性复合作(MHC)是脊椎动物中普遍存在的一个紧密连锁的基因复合体。主要组织相容性抗原是能引起强烈移植反应的一组抗原,编码该抗原的基因也是一组基因,遗传学上把这一连锁群称为主要组织相容性系统(MHS)。七十年代初不少研究者相继报道了特异性牛淋巴细胞抗原的存在,但直至1977年人们才找到牛淋巴细胞抗原(BOLA)是受遗传控制且具有多态性的证据。随后Amorena等(1978)发现BOLA是牛MHC的一部分。 Antczak(1982)认为MHC的研究仅     

Na2ATP对尾部悬吊大鼠比目鱼肌梭内、外肌纤维MHC表达的影响

目的 探讨三磷酸腺苷二钠盐（Na2ATP）对尾部悬吊大鼠比目鱼肌（SOL）梭内、外肌纤维肌球蛋白重链（MHC）表达的影响。方法 采用大鼠尾部悬吊法建立废用模型，用免疫组织化学技术，观察Na2ATP注射液对大鼠比目鱼肌（SOL）梭内、外肌纤维MHC表达的影响。结果 尾部悬吊14d后大鼠比目鱼肌梭内、外肌纤维中快缩型MHC的表达均有所增加，而在尾吊期间注射Na2ATP后比目鱼肌梭内、外肌快缩型MHC表达没有明显变化。结论 Na2ATP注射液对尾部悬吊大鼠比目鱼肌梭内、外肌纤维MHC表型转化有明显的对抗作用。     

主要组织相容性复合体Ⅱ和γ-干扰素在CO中毒迟发性脑病大鼠模型脑内的表达

目的探讨CO中毒迟发性脑病(DNS)大鼠模型脑内主要组织相容性复合体Ⅱ(MHCⅡ)和γ-干扰素(IFN-γ)的表达,分析其发病机制。方法建立CO中毒DNS大鼠模型,用HE染色观察大鼠脑组织病理学变化,用免疫组织化学方法检测大鼠脑内MHCⅡ和IFN-γ的表达。结果HE染色标本上,正常对照组大鼠脑内细胞形态正常,DNS大鼠脑皮质出现大片疏松区,海马锥体细胞层稀疏,可见点片状坏死。免疫组化结果显示,对照组无或仅有少量MHCⅡ和IFN-γ表达;DNS组有表达,MHCⅡ3d表达增强,7d达高峰,10d呈零星分布,20d几乎无阳性细胞;IFN-γ3d表达高峰,7d有所下降, 10d、20d呈零星分布。结论与对照组相比,DNS大鼠脑组织存在明显的病理学改变,MHCⅡ和IFN-γ的表达明显增多,且在时间上有一定顺序,提示免疫因素可能参与了DNS的发病过程。     

病毒感染心肌细胞的心肌肌凝蛋白重链基因表达和细胞力学

目的：探讨病毒直接损伤心现细胞的机制。方法：采用柯萨奇B3病毒感染体外培养心现细胞，检测心肌细胞收缩力以及心肌细胞的α－MHC和β－MHC的基因表达，并与正常心肌细胞相对比。结果：柯萨奇B3病毒感染后的心肌细胞收缩力比正常心肌细胞的心肌收缩力明显降低（P＜0．01），并且感染后24h比12h下降更为显著（P＜0．05），心肌细胞收缩蛋白α－MHC和β－MHC的基因表达也发生了改变，阿萨奇B3病毒感染后心肌细胞的α－MHC基因表达明显降低，而β-MHC基因表达升高，结论：柯萨奇B3病毒感染后的心肌细胞收缩力下降，使心肌细胞以α－MHC基因表达为主转向以β－MHC基因表达为主。     

转人类胰岛素样生长因子-Ⅰ基因成肌细胞对骨骼肌急性钝挫伤后Ⅱb型肌球蛋白重链及波形蛋白mRNA表达的影响

目的:观察转人类胰岛素样生长因子-Ⅰ(HumanInsulin -likeGrowthFactor-Ⅰ,hIGF -Ⅰ)基因成肌细胞回输小鼠骨骼肌钝挫伤局部后,对小鼠骨骼肌愈合过程中Ⅱb型肌球蛋白重链(MyosinHeavyChain -Ⅱb ,MHC -Ⅱb)及波形蛋白(Vimentin)mRNA表达的影响。方法:将90只7～12周雄性C3H小鼠右下肢腓肠肌中段内侧实施急性钝挫伤后,随机分为自然愈合组、单纯成肌细胞注射组和转基因成肌细胞注射组。挫伤后第3天,对单纯成肌细胞注射组、转基因成肌细胞注射组损伤局部分别注射等量单纯成肌细胞和转基因成肌细胞,并于损伤后第1、5、10、2 0、30天取材。检测不同时间点MHC -Ⅱb和VimentinmRNA表达水平,观察比较各组骨骼肌修复情况。结果:(1)在急性骨骼肌钝挫伤修复期,3组小鼠骨骼肌MHC -ⅡbmRNA均明显升高,第2 0天达到峰值。转基因成肌细胞注射组MHC -ⅡbmRNA表达水平最高,其次为单纯成肌细胞注射组。(2 )急性骨骼肌钝挫伤修复过程中,转基因成肌细胞注射组VimentinmRNA的表达水平始终在3组中表达最低。结论:急性骨骼肌钝挫伤修复过程中,注射转基因成肌细胞能提高损伤后MHC -IIbmR NA表达水平,促进肌纤维的增生,加速骨骼肌愈合进程。同时,损伤局部注射转hIGF -Ⅰ基因的成肌细胞后,使得损伤局部VimentinmRNA表达低于另两组,一     

大鼠骨髓多能成体祖细胞转化为皮肤组织细胞的在体研究

目的 观察大鼠骨髓多能成体祖细胞(mulipotent adult progenitor cells,MAPCs)是否可在体向皮肤组织细胞分化.方法 采用免疫磁性分选技术(MACS)获取MAPCs;通过皮肤受损的C57BL/6小鼠与免疫缺陷性裸鼠的尾静脉注入MAPCs,免疫组织化学技术检测愈合皮肤中大鼠MHC I类抗原的表达.结果 MHC I抗原在C57BL/6小鼠愈合皮肤处的毛囊皮脂腺周围及毛囊外根鞘与皮脂腺交界处均有阳性表达细胞;裸鼠实验组愈合皮肤内出现毛囊样结构,在表皮基底部及部分毛囊样结构中有MHC I抗原阳性表达的细胞.结论 在皮肤组织损伤的条件下,MAPCs可迁移至受损皮肤表面及皮肤附属器毛囊周围,并通过转化为表皮细胞参与受损皮肤的愈合.     

AT2R基因转染对树突状细胞成熟和免疫功能的影响

目的研究血管紧张素Ⅱ2型受体(AT2R)基因表达对树突状细胞(DC)成熟及免疫功能的影响,探讨AT2R参与动脉粥样硬化斑块进展的免疫炎性反应机制。方法用免疫磁珠分离纯化C57BL/6J小鼠骨髓细胞,体外培养为DC,再转染携带绿色荧光蛋白的AT2R基因重组腺病毒载体(p Ad CMV/AT2R)或空病毒载体(p Ad-GFP),分为对照组、脂多糖组、p AdGFP组、p Ad CMV/AT2R组及p Ad CMV/AT2R+AT2RB组(AT2R拮抗剂)。用荧光显微镜、RT-PCR、Western印迹检测绿色荧光及AT2R mRNA和蛋白表达水平;流式细胞术检测DC表面标志CD86和MHCⅡ的表达率;MTT检测DC刺激T淋巴细胞增殖能力;ELISA检测细胞因子白细胞介素-12(IL-12)和干扰素-γ(IFN-γ)水平。结果 DC转染病毒后有绿色荧光及AT2R mRNA和蛋白的表达,p Ad CMV/AT2R组CD86和MHCⅡ的表达、T淋巴细胞增殖和细胞因子分泌量都较对照组高(P<0.01),但比脂多糖组显著降低(P<0.05或P<0.01),p Ad CMV/AT2R+AT2RB组上述变化也显著高于对照组(P<0.01),但与脂多糖组比较无显著差异(P>0.05)。结论 DC表达AT2R基因,AT2R能抑制DC成熟诱导的局部免疫炎性反应,推测AT2R可能介导抑制动脉粥样斑块的进展。     

Sarcomeric myosin heavy chain gene family: organization and pattern of expression

The sarcomeric myosin heavy chains (MHCs), which exhibit different levels of ATPase activity, are encoded by a closely related multigene family from which seven members have been identified and characterized in the rat. The MHC genes appear to map to a single chromosome, and at least two of them, alpha- and beta-cardiac, are closely linked in the genome. Each of these genes is approximately 25 kilobases long, and their coding sequences are interrupted by 40 introns. Each MHC gene displays a pattern of expression that is tissue-specific and developmentally regulated, with more than one MHC gene expressed in each muscle and developmental stage. Moreover, with the exception of the extra-ocular muscle MHC gene that has a very specific pattern of expression, the other genes are all expressed in more than one tissue. The expression of all MHC genes can be modulated by thyroid hormone. Surprisingly, however, the same myosin heavy chain gene can be regulated by thyroid hormone in highly different modes, even in opposite directions, depending on the tissue in which it is expressed. Furthermore, the skeletal embryonic and neonatal myosin heavy chain genes, so far considered specific to these two developmental stages, can be re-induced by hypothyroidism in specific adult muscles.     

Effects of high intensity resistance and low intensity endurance training on myosin heavy chain isoform expression in highly trained rowers

An important mechanism of muscle adaptation to exercise is the alteration of myosin heavy chain (MHC) isoform expression. This study investigated the effect of a high intensity resistance training (HIRT) and a low intensity endurance rowing (LIER) on MHC isoform expression in highly trained human muscle. Six well-trained male rowers underwent a training program consisting of a 3-week HIRT and a 3-week LIER, each followed by one-week of recovery. Muscle samples were taken from vastus lateralis before and at the end of each training and recovery phase. MHC isoform was analyzed by SDS-PAGE using silver stain and MHC isoform mRNA by RT-PCR. The maximum oxygen uptake and power output did not change after the training. MHC isoform composition did not change over HIRT or LIER, and there was a decrease in MHC I with concomitant increase in MHC IIa after recovery following HIRT. HIRT led to mRNA upregulation of MHC Ialpha, Ibeta and IIx (127 %, 148 % and 117 %, respectively, p < 0.05), but not MHC I protein (60 % vs 62 %, NS), and LIER led merely to MHC Ibeta mRNA upregulation (131 %, p < 0.05). Thus, different responses of MHC isoform expression to HIRT and LIER occurred in the highly trained muscle, and a "ceiling effect" in terms of MHC I expression could be observed. The upregulation of MHC Ialpha mRNA in human skeletal muscle documented in this study may encourage further observations in this field.     

Single muscle fiber myosin heavy chain distribution in elite female track athletes

PURPOSE: Myosin heavy chain (MHC) characterization of tissue samples from the gastrocnemius muscle of six elite female athletes and 10 untrained females was performed using myosin ATPase histochemistry and gel electrophoresis. Athletes were of national and international caliber, whereas their untrained counterparts were healthy individuals not involved in a regular exercise program. METHODS: Muscle biopsies for the athletes were performed 14 wk into their training season and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and myosin ATPase techniques. RESULTS: Electrophoretic analysis of single muscle fibers from elite athletes revealed a MHC phenotype composition of 46 +/- 6% type I, 21 +/- 6% type IIa, and 0% type IIx, whereas 34% of the single fibers expressed multiple MHC isoforms. When compared with the elite women, untrained subjects demonstrated higher percentages of type I MHC and lower percentages of IIa MHC muscle fibers, 57 +/- 5 and 16 +/- 3%, respectively (P < 0.05). Similar to the female athletes, 27% of the fibers from untrained women possessed multiple myosin isoforms. Myosin ATPase staining demonstrated a greater percentage of type I fibers in untrained subjects versus the elite women (67 +/- 3 vs 41 +/- 2%, P< 0.05) (mean +/- SE), whereas the athletes had a higher percentage of type IIa fibers compared with the untrained women (49 +/- 5 vs 19 +/- 2%, P< 0.05). There were no differences in the percentage of IIb fibers between elite and untrained women (11 +/- 4 vs 14 +/- 2%, respectively). CONCLUSIONS: Whereas a preponderance of hybrid fibers is generally observed in untrained populations, the diverse MHC phenotype seen in these elite female athletes is uncommon. These unique findings are attributed to the chronic and varied nature of training in which these athletes were involved.     

The profile and distribution of myosin heavy chain isoforms in middle-aged sedentary persons

AIM: Human lifestyle has drastically changed during the past century as the share of physical work in daily life has decreased. The purpose of the present study was to examine the distribution of myosin heavy chain (MHC) isoforms in middle-aged sedentary persons, to compare the proportion of MHC isoforms of middle-aged and young sedentary persons and to demonstrate the effect of physical activity of MHC isoforms in middle-aged sedentary persons. METHODS: Eighty-nine middle-aged sedentary and 13 young sedentary persons volunteered for the study. Thirty middle-aged sedentary subjects participated in strength-conditional exercise program during 9 months. Vertical jumping height and maximal anaerobic work capacity were measured. Muscle samples were taken from vastus lateralis muscle. MHC isoform composition was determined by SDS-PAGE. RESULTS: Variation of MHC I and MHC IIa isoforms in middle-age sedentary persons demonstrated normal distribution. Significant differences of MHC isoform proportions between middle-aged and young sedentary participants were not observed. The proportion of MHC IIx decreased significantly after the exercise period that significantly improved the maximal anaerobic power and jumping height of participants. CONCLUSIONS: Normal distribution illustrated the proportion of MHC I and MHC IIa isoforms in 89 middle-aged sedentary persons while significant differences of MHC isoforms proportion between young and middle-aged sedentary persons were not observed. Even small increase of physical activity improved physical performance and decrease the MHC IIx proportion of middle-aged sedentary persons. Physically active lifestyle in middle age, when age-related changes have not started yet, may delay age-related changes in skeletal muscle.     

肌球蛋白重链II_xmRNA表达可能为大鼠比目鱼肌废用的分子标志

目的建立大鼠跟腱切断模型 ,观测并比较跟腱切断与尾部悬吊大鼠比目鱼肌重量与肌球蛋白重链 (MHC)异构体mRNA表达的变化 ,为探讨骨骼肌废用性萎缩的机理提供实验线索。方法选取雄性SD大鼠 30只 ,随机分为 6组 ,每组 5只。直接切断跟腱 ,称量肌腱切断后第 1、3、7、1 4、2 1、2 8天比目鱼肌 (SOL)、腓肠肌内外侧头 (MG ,LG)与跖肌 (PL)的湿重。用RT PCR法观测SOLMHC异构体mR NA的表达。结果跟腱切断后第 3天 ,SOL出现明显萎缩 ,在第 7与 1 4天萎缩达最低点 ,从第 2 1天开始 ,萎缩的SOL重量有所恢复。MG、LG与PL重量的变化趋势与SOL基本一致。在正常SOL中 ,仅有MHCI与IIa mRNA表达。从跟腱切断的第 3天开始直至第 2 8天 ,SOL中出现MHCIIx mRNA的表达 ,但无MHCIIb 的表达。结论跟腱切断引起的SOL萎缩在出现时间与程度上 ,与尾部悬吊相似。两种模型均可引起SOL中MHCIIx mRNA表达 ,推测MHCIIx 可能为骨骼肌废用的分子标志     

Myosin heavy chain isoform expression: influence on isoinertial and isometric performance

Thirty-six healthy men with varying degrees of physical training background performed maximal-effort isometric and isoinertial knee extensor actions, with relative loads equal to 40% and 70% of one-repetition maximum. Force, velocity, and power were derived from force and linear position transducers at 500 Hz. Biopsies were taken from the vastus lateralis and analyzed by SDS-PAGE for relative myosin heavy chain (MHC) content. Relative MHC IIx content was included in a regression model, and explained variance noted. Relative MHC I content was subsequently added to the regression model to determine what, if any, additional variance was explained beyond that of MHC IIx. Results indicated that no relationship (r = 0.0 to 0.1) exists between the relative expression of MHC isoforms from the vastus lateralis and isometric/isoinertial performance in a population with diverse training backgrounds. Lack of nervous system adaptations in the untrained subjects in the study possibly attenuates the significant relationship between MHC and in-vivo muscle performance previously established in trained populations.     

Repeated high‐intensity exercise modulates Ca2+ sensitivity of human skeletal muscle fibers

The effects of short‐term high‐intensity exercise on single fiber contractile function in humans are unknown. Therefore, the purposes of this study were: (a) to access the acute effects of repeated high‐intensity exercise on human single muscle fiber contractile function; and (b) to examine whether contractile function was affected by alterations in the redox balance. Eleven elite cross‐country skiers performed four maximal bouts of 1300 m treadmill skiing with 45 min recovery. Contractile function of chemically skinned single fibers from triceps brachii was examined before the first and following the fourth sprint with respect to Ca²⁺ sensitivity and maximal Ca²⁺‐activated force. To investigate the oxidative effects of exercise on single fiber contractile function, a subset of fibers was incubated with dithiothreitol (DTT) before analysis. Ca²⁺ sensitivity was enhanced by exercise in both MHC I (17%, P < 0.05) and MHC II (15%, P < 0.05) fibers. This potentiation was not present after incubation of fibers with DTT. Specific force of both MHC I and MHC II fibers was unaffected by exercise. In conclusion, repeated high‐intensity exercise increased Ca²⁺ sensitivity in both MHC I and MHC II fibers. This effect was not observed in a reducing environment indicative of an exercise‐induced oxidation of the human contractile apparatus.     

Role of CaMKII and sarcolipin in muscle adaptations to strength training with different levels of fatigue in the set

Strength training promotes a IIX‐to‐IIA shift in myosin heavy chain (MHC) composition, likely due to changes in sarcoplasmic [Ca²⁺] which are sensed by CaMKII. Sarcoplasmic [Ca²⁺] is in part regulated by sarcolipin (SLN), a small protein that when overexpressed in rodents stimulates mitochondrial biogenesis and a fast‐to‐slow fiber type shift. The purpose of this study was to determine whether CaMKII and SLN are involved in muscle phenotype and performance changes elicited by strength training. Twenty‐two men followed an 8‐week velocity‐based resistance training program using the full squat exercise while monitoring repetition velocity. Subjects were randomly assigned to two resistance training programs differing in the repetition velocity loss allowed in each set: 20% (VL20) vs 40% (VL40). Strength training caused muscle hypertrophy, improved 1RM and increased total CaMKII protein expression, particularly of the δ_D isoform. Phospho‐Thr²⁸⁷‐CaMKII δ_D expression increased only in VL40 (+89%), which experienced greater muscle hypertrophy, and a reduction in MHC‐IIX percentage. SLN expression was increased in VL20 (+33%) remaining unaltered in VL40. The changes in phospho‐Thr²⁸⁷‐CaMKII δ_D were positively associated with muscle hypertrophy and the number of repetitions during training, and negatively with the changes in MHC‐IIX and SLN. Most OXPHOS proteins remained unchanged, except for NDUFB8 (Complex I), which was reduced after training (?22%) in both groups. The amount of fatigue allowed in each set critically influences muscle CaMKII and SLN responses and determines muscle phenotype changes. With lower intra‐set fatigue, the IIX‐to‐IIA MHC shift is attenuated.     

肌球蛋白重链Ⅱx mRNA表达可能为大鼠比目鱼肌废用的分子标志

目的：建立大鼠跟腱切断模型，观测并比较跟腱切断与尾部悬吊大鼠比目鱼肌重量与肌球蛋白重链（MHC）异构体mRNA表达的变化，为探讨骨骼肌废用性萎缩的机理提供实验线索。方法：选取雄性SD大鼠30只，随机分为6组，每组5只，直接切断跟腱，称量肌腱切断后第1，3，7，14，21，28天比目鱼肌（SOL），腓肠肌内外侧头（MG，LG）与跖肌（PL）的湿重，用RT－PCR法观测SOL MHC异构体mRNA的表达，结果：跟腱切断后第3天，SOL出现明显萎缩，在第7与14天萎缩达最低点，从第21天开始，萎缩的SOL重量有所恢复，MG，LG与PL重量的变化趋势与SOL基本一致。在正常SOL中，仅有MHC1 MHC Ⅱb的表达。结论：跟腱切断引起的SOL萎缩在出现时间与程度上，与尾部悬吊相似，两种模型均可引起SOL中MHC，Ⅱx mRNA表达，推测MHCⅡx可能为骨骼肌废用的分子标志。