胰岛素抵抗大鼠骨骼肌蛋白激酶B的表达

蛋白激酶 B(protein kinase B,PKB)具有促进生长、增殖、抑制凋亡的作用,对糖代谢有明显影响.本研究通过高脂喂养诱导Sprague-Dawley(SD)大鼠产生胰岛素抵抗,检测大鼠骨骼肌中胰岛素诱导的蛋白激酶B的表达的改变,揭示胰岛素抵抗与蛋白激酶B表达的关系.

MITOCHONDRIAL BIOGENESIS AND SLOW MUSCLE GENE EXPRESSIONRecent findings in proxisome proliferators-activated recep tor γ (PPARγ) coactivator-1α (PGC-1α) gene regulation and function have led to the consideration of PGC-1α as a key regulator in regulating important features of skeletal muscle adaptation.PGC-1α is a transcriptional coactivator cloned originally by a yeast-two-hybrid screen from a differentiated brown fat cell line using PPARγ as bait[80]. PGC-1α mRNA and protein are highly expressed in slow,oxidative fibers compared to the fast, glycolytic fibers[81-82],consistent with the function of a gene involved in fiber type specialization. The functional importance of PGC-1α in striated muscles has been suggested by several different models [83-84].

胰岛素样生长因子-1对慢性肾功能不全大鼠骨骼肌蛋白质合成与分解的影响

目的探讨胰岛素样生长因子(IGF-1),在CRF大鼠及配对喂养的假手术(ShamOperated,SO)对照组大鼠骨骼肌蛋白质代谢上的作用.方法从两组大鼠血清和骨骼肌中提取IGF-1,用放射免疫分析法测定血清及骨骼肌中的IGF-1水平;用荧光测定法检测肱骨内上髁肌培养液中总酪氨酸的浓度,进而计算基础蛋白合成率及分解率.通过剂量反应试验,观察不同浓度重组人类胰岛素样生长因子-1(rhIGF-1)对骨骼肌蛋白质合成与分解的影响.结果CRF大鼠血清IGF-1浓度显著低于SO对照大鼠(170.3±16.4比410.4±49.3ng/ml),骨骼肌IGF-1含量也明显低于SO组(4.22±1.03比6.93±1.4lng/g),P值均<0.001.CRF组大鼠肱骨内上髁肌的基础蛋白合成串(24.0±2.1nmol酪氨酸·g肌肉-1·h-1)比SO组(30.8±2.4nmol酪氨酸·g肌肉-1·h-1)低22%,P<0.05.而基础蛋白分解率则比SO组高78%(234.4±13.8比131.7±8.4nmol酪氨酸·g肌肉-1.h-1,P<0.001.剂量反应试验发现,rhlGF-1对CRF大鼠骨骼肌蛋白质合成和分解的作用明显低于SO大鼠.浓度为25-500ng/ml的rhlGF-1对CRF大鼠蛋白质合成的促进作用仅为SO大鼠的25%～44%,对蛋白质分解的抑制作用仅为对照组的15%～42%.说明CRF大鼠骨骼肌对rhlGF-1促进蛋白质合成代谢的反应性降低.结论CRF时血清及骨骼肌的IGF-1含量减少,骨骼肌对IGF-1促进蛋白质合成代谢的作用存在抵抗,这些可能是CRF患者骨骼肌蛋白质合成减少、分解增强,进而导致营养不良、肌肉萎缩的主要原因.

心脏术后早期患儿应用胰岛素严格控制血糖无益于减少骨骼肌降解

心脏术后早期患儿应用胰岛素严格控制血糖无益于减少骨骼肌降解/ Tight glycemic control with insulin does not affect skeletal muscle degradation during the early post-operative pe-riod following pediatric cardiac surgery. Fisher JG，Sparks EA，Khan FA，et al. Pediatr Crit Care Med，2015，16（6）：515-521.
　　关键词严格控制血糖；危重症；儿童；蛋白水解；分解代谢；胰岛素
　　摘要
　　目的危重症可导致分解代谢显著增强，而持续性蛋白丢失和患病率及病死率升高有关。胰岛素为强效抗分解代谢激素；大剂量胰岛素可减少危重手术患儿骨骼肌蛋白分解。然而尚无研究分析临床剂量的胰岛素对蛋白分解的作用。本研究旨在评估术后严格控制血糖及应用临床剂量胰岛素对体外循环心脏术后患儿骨骼肌分解的影响。

Previous studies have conifrmed that heat shock protein 90 overexpression can lead to dopami-nergic neuronal death. This study was designed to further investigate what effects are produced by heat shock protein 90 after endurance exercise training. Immunohistochemistry results showed that exercise training signiifcantly inhibited heat shock protein 90 overexpression in the soleus and gastrocnemius in Parkinson’s disease rats, which is a potential therapeutic target for ameliorating skeletal muscle abnormalities in Parkinson’s disease.

骨骼肌疾病的临床病理诊断

骨骼肌的病理检查在众多肌肉病相关的辅助检查方法中有诊断价值.20世纪60年代开展的肌肉活检冰冻切片技术以及电生理检查技术促进了骨骼肌疾病的研究和诊断,此后的神经生化检查为代谢性肌肉病的诊断提供了更多的依据,影像学的应用为观察肌肉损害的全身分布和肌肉活检部位的选择提供了重要参考,基因和免疫细胞化学方法的应用促进了分子肌肉病理学的发展[1],使骨骼肌病理检查在鉴别疾病相关结构、为治疗策略提供形态学依据以及研究发病机制方面[2]更显重要.

骨骼肌特异性microRNA-206在骨骼肌卫星细胞再生过程中的表达

尽管运动性骨骼肌损伤(Exercise-induced Skeletal Muscle Injury)和修复一直是运动医学界研究的热点问题之一,但是骨骼肌损伤后再生修复过程中的许多机制性问题并未解决.卫星细胞的发现推动了骨骼肌再生研究的飞速发展.现已证实,所有哺乳动物的骨骼肌都具有再生能力,卫星细胞是肌肉损伤后功能修复的唯一来源.卫星细胞位于肌细胞膜与基膜之间,正常生理状态下处于静息状态,肌肉损伤时被激活进入分裂期,不断增殖、融合为肌管,随后收缩蛋白和调节蛋白开始表达,胞质中出现肌原纤维,核移位于细胞边缘,分化成为成熟的肌纤维.近年来的研究表明,microRNA可能在卫星细胞的增殖分化过程中起到重要作用.

Increased non-oxidative and oxidative ATP production via metabolic pathways in skeletal muscle is essential for the maintenance of force and power production during exercise. However, substrate depletion and accumulation of metabolic byproducts are potential causes of fatigue. Reduced PCr availability can limit power production during sprint exercise, whereas carbohydrate depletion is a major limitation to endurance performance. During sprint exercise increased Pi and H+ may contribute to fatigue, and during prolonged strenuous exercise, the accumulation of NH3, reactive oxygen species, and heat can limit performance. Appropriate training programs and nutritional interventions are potential strategies to enhance fatigue resistance and exercise performance.

CT和MRI功能成像在慢性骨骼肌缺血的研究进展

慢性骨骼肌缺血即由于各种原因导致的骨骼肌长期慢性的缺血缺氧改变.引起慢性骨骼肌缺血常见的原因是外周动脉闭塞性疾病(Peripheral Arterial Occlusive Disease,PAOD),通常指周围动脉硬化性闭塞症,是由于动脉粥样硬化导致动脉狭窄、闭塞引起的缺血性疾病,常见于下肢.由于组织缺血造成肌肉和神经的营养障碍,表现为下肢疼痛、间歇性跛行,病情严重时可引起足趾溃疡和坏疽.

脊髓损伤后骨骼肌变化及预后的研究进展

脊髓损伤是脊柱骨折严重的并发症.由于椎体的移位或碎片骨突出于椎管内,使脊髓产生不同程度的损伤.在脊髓损伤之后,其效应器之一,骨骼肌将不可避免的发生一些相应的变化:凋亡、萎缩、运动单位的改变;肌肉兴奋性、收缩能力的改变;肌球蛋白重链的表达以及3-磷酸甘油脱氢酶活性的改变等,这些变化影响脊髓损伤的预后及患者的生活质量.目前针对脊髓损伤后骨骼肌变化的研究方法主要是从运动训练及电刺激这两方面.

We aimed to determine the mechanisms of the anabolic actions of androgens in skeletal muscle by investigating potential androgen receptor(AR)?regulated genes ininvitroandinvivomodels. The expression of the myogenic regulatory factormyogenin was signiifcantly decreased in skeletal muscle from testosterone?treated orchidectomized male mice compared to control orchidectomized males, and was increased in muscle from male AR knockout mice that lacked DNA binding activity(ARΔZF2) versus wildtype mice, demonstrating thatmyogenin is repressed by the androgen/AR pathway. The ubiquitin ligaseFbxo32 was repressed by 12h dihydrotestosterone treatment in human skeletal muscle cell myoblasts, andc?Myc expression was decreased in testosterone?treated orchidectomized male muscle compared to control orchidectomized male muscle, and increased in AR?ZF2 muscle. The expression of a group of genes that regulate the transition from myoblast proliferation to differentiation, Tceal7, p57Kip2, Igf2 andcalcineurin Aa, was increased in AR?ZF2 muscle, and the expression of all butp57Kip2was also decreased in testosterone?treated orchidectomized male muscle compared to control orchidectomized male muscle. We conclude that in males, androgens act via the AR in part to promote peak muscle mass by maintaining myoblasts in the proliferative state and delaying the transition to differentiation during muscle growth and development, and by suppressing ubiquitin ligase?mediated atrophy pathways to preserve muscle mass in adult muscle.

生长分化因子-8与骨骼肌再生

再生常意味着细胞的分裂增殖,但传统观点认为,骨骼肌属于永久性细胞(permanent cell),又称终末细胞,成熟的骨骼肌不能再生,肌纤维的有丝分裂罕见.是否成熟的骨骼肌内存在某种抑制细胞分裂增殖的特异性控制因子(或是增殖因子的缺陷、失活或不表达),长期以来,是生物医学界试图解决的课题.随着分子生物学的发展,不仅证实了骨骼肌的再生[1-5],而且发现多种生长因子对骨骼肌再生有一定的积极作用[6-11],其中新近发现的生长分化因子-8(growth differentiation factor-8,GDF-8)对骨骼肌生长发育的负调节作用更为突出,又称为肌肉生长抑制素(Myostatin,Mstn),属于转化生长因子β(transforming growth factor-beta,TGF-β)超家族成员.

伴骨骼肌分化的小细胞神经内分泌癌--附3例报道

向骨骼肌方向分化是一种十分少见的现象但却普遍存在于人类多种肿瘤中。作者观察了3例含有横纹肌母细胞成分的神经内分泌癌的病理特征。 3例中男性2例，分别为77岁和75岁，发生于臀部皮下组织和膀胱；女性1例，70岁，发生于左侧鼻腔内。瘤体小者为3．5 Cm皮下结节大者充满膀胱腔并侵犯周围软组织，边界不清。3例均经广泛手术切除，1例行术后放疗，1例行辅助化疗。除1例女性失访外，2例男性分别在术后2周和肿瘤初发后11个月死于肿瘤的广泛侵袭和转移。

游离骨骼肌自体移植的实验研究与临床应用

本文介绍游离骨骼肌自体移植术代尿道括约肌2例,代耻骨直肠肌2例,矫治前臂缺血性挛缩1例.经过半年到三年随访,功能满意.动物实验结果表明,去神经后的骨骼肌无组织学改变,但SDH的活性降低.电镜检查见到肌原纤维中有空泡和糖原沉积,说明糖和脂肪分解代谢降低,有利于移植肌在无血供期生存.由于ATPase活性未降低,移植肌尚存在收缩功能.

Orexins, hypothalamic neuropeptieds, are involved in modulation of food intake and arousal state. To examine further physiological roles of orexin in brain function, the effects of centrally administered orexin- A on body temperature was investigated in rats. Assessed by a telemetry-sensor system implanted into the abdominal cavity, infusion of orexin-A into the third cerebroventricle increased body temperature in a dose-responsive manner. Cumulative ambulatory activity was concomitantly increased during 6 h but not 12 h after administration of orexin-A. Expression of uncoupling protein 1 (UCP1) mRNA in brown adipose tissue, as a marker for peripheal thermogenesis which affects body temperature, failed to increase after orexin-A administration. Expression of UCP3 mRNA in skeletal muscle but not UCP 2 in white adipose tissue was upregulated by infusion of orexin-A. The resulting information indicates that orexin neuron regulates body temperature in coordination with control of arousal system independently of peripheral thermogenesis through the BAT UCP1.

AIM: To study the changes in capillarity of skeletal muscle during acclimation to high altitude, and explore the effects of a certain extent physical activity under hypoxia on capillary formation and the role of vascular endothelial growth factor (VEGF) in this process. METHODS: 48 Wistar rats were divided into 3 groups: Ⅰ normoxic control; Ⅱ hypoxia and Ⅲ hypoxia+exercise. Rats of Ⅱ and Ⅲ groups were subjected to hypobaric hypoxia for 5 weeks (23 h/d). They were first brought to simulated 4 000 m altitude, where rats of the Ⅲgroup were forced to swim for 1 h/d (6 d/week). Then the animals were ascent to 5 000 m. Biomicrosphere method was used to determine blood flow of skeletal muscle. The mean fiber cross-sectional area (FCSA), capillary density (CD) and capillary/fiber ratio (C/F) of red portion of the lateral head of the gastrocneminus were assayed by myofibrillar ATPase histochemistry. VEGF and its receptor KDR were assayed with immunohistochemistry method.RESULTS: By comparison with the normoxic control, 5-week hypoxic exposure resulted in a decrease in cross-sectional area of skeletal muscle fiber and an increase in CD, but the C/F remained unchanged. The blood supply to the gastrocnemius was not changed. After 5-week-exercise at high altitude, the muscle fibers did not undergo atrophy. CD, C/F, and the blood flow at rest increased significantly. VEGF protein was found primarily in the matrix between muscle fibers; KDR were shown mainly in endothelial cells of capillary. VEGF was more strongly stained in the skeletal muscle of hypoxia-exercise rats.CONCLUSION: Hypoxia itself can not induce neovascularization. While exercise during hypoxic exposure can lead to capillary formation. VEGF and KDR may play roles in it. New capillary formation benefits the blood supply, oxygen delivery and working performance at high altitude.

AIM:Cytochrome P450 epoxygenase 2J2 and epoxyeicosatrienoic acids ( EETs) are known to protect against cardiac hypertrophy and heart failure, which involve activation of 5′-AMP-activated protein kinase ( AMPK) and Akt.Although the functional roles of AMPK and Akt are well established , the significance of crosstalk between them in the development of cardiac hypertrophy and anti -hy-pertrophy of CYP2J2 and EETs remains unclear .Here, we investigated whether CYP 2J2 and its metabolites EETs protected against cardiac hypertrophy by activating AMPKα2 and Akt1.Moreover, we tested whether EETs enhanced crosstalk between AMPKα2 and phosphorylated Akt1 ( p-Akt1), and stimulated the nuclear translocation of p-Akt1, to exert their anti-hypertrophic effects. METHODS:The recombinant rAAV9 vector was coupled to CYP2J2 and the rAAV9-CYP2J2 construct was injected into the caudal vein of AMPKα2-/-and littermate control mice .AMPKα2 -/-and littermate control mice that overexpressed CYP 2J2 in heart were treated with angiotensin II (Ang II) for 2 weeks.Hemodynamic and cardiac functions were also evaluated after 14 days of infusion with Ang II or saline.RESULTS:Interestingly, the overexpression of CYP2J2 suppressed cardiac hypertrophy , including decreased heart size, cross sectional area of cardiomyocytes , markers of cardiac hypertrophy [ brain natriuretic peptide ( BNP) ,β-myosin heavy chain (β-MHC) and skeletal muscle α-actin (ACTA1)] and increased levels of atrial natriuretic peptide (ANP) in the heart tissue and plasma of wild-type mice but not AMPKα2 -/-mice.Measurement of left ventricular ejection fraction and fractional shortening showed that CYP2J2 overexpression prevented Ang II-induced ventricular systolic dysfunction in mice .Moreover, an Ang II-induced reduction in cardiac function, demonstrated by decreased dp/dtmax and dp/dtmin, was prevented by overexpression of CYP2J2.Mechanistically, the CYP2J2 metabolites 11,12-EET activated AMPKα2 to induce the nuclear translocation of p-Akt1, which increased production of ANP and thereby inhibited the development of cardiac hypertrophy .Furthermore , by co-immunoprecipitation analysis , we found that full-length Akt1 and an Akt1 fragment containing amino acids 150-408, which constitute the protein kinase domain , but not other frag-ments of Akt1, bind to the AMPKγ1 subunit.AMPKα2β2γ1 and p-Akt1 interact through the direct binding of the AMPKγ1 subunit to the Akt1 protein kinase domain.This interaction was enhanced by 11,12-EET.CONCLUSION:Our studies reveal a novel mechanism in which CYP2J2 and EETs enhanced Akt1 nuclear translocation through interaction with AMPKα2β2γ1 and protect against cardiac hy-pertrophy and suggest that overexpression of CYP 2J2 might have clinical potential to suppress cardiac hypertrophy and heart failure .

AIM:R-spondin 2 (Rspo2), one member of R-spondin family which contains four secreted proteins , plays an important role in skeletal muscle development .However, the impact of Rspo2 on vascular smooth muscle cell ( SMC) differentiation is little known . This study aims at revealing the role and mechanism of Rspo 2 on SMC differentiation from embryonic stem cells (ESCs).METHODS:A well-established model for studying SMC differentiation from ESCs were used , in which mouse embryonic stem cells ( ES-D3) were seeded on collagen IV-coated flasks and cultured in differentiation medium (DM) for 2, 4, 6 and 8 days.Smooth muscle specific markers, includingα-smooth muscle actin (α-SMA), SM22 and smooth muscle myosin heavy chain (SM-MHC), were detected to in-sure the successful model by qRT-PCR and Western blot .After 3-day pre-differentiation, ESCs were treated with recombinant Rspo 2 protein, overexpression plasmid or shRNA plasmid for 96 h, and the mRNA and protein expression of smooth muscle markers was detected.To explore the role of Rspo2 on SMC differentiation in vivo, 3-day predifferentiated ESCs (106 in 50μLα-MEM) incubated with Rspo2-overexpression plasmid were mixed with 50 μL of Matrigel ( Becton Dickinson Labware ) and then subcutaneously injected into C57BL/6J mice.After 12 days, mice were sacrificed and the implants were harvested for immunofluorescence staining , qRT-PCR and Western blot.Furthermore, electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation assay (ChIP) and lucif-erase reporter assay were performed to investigate the transcriptional activity of SMC differentiation related transcription factors , inclu-ding serum response factor (SRF), myocardin (MYO), myocyte-specific enhancer factor 2C (MEF-2C).Involvement of Rspo2 re-ceptor, leucine-rich repeat-containing, G-protein-coupled receptors (Lgr)4,5,6, and β-catenin pathway during Rspo2-induced MSC differentiation were also uncovered by overexpression or inhibition of the respective protein .RESULTS:Our results showed that Rspo 2 mRNA and protein expression was significantly and consistently increased during ESC differentiation towards SMCs .Recombinant Rs-po2 protein and enforced Rspo 2 expression in ESCs resulted in up-regulation of smooth muscle markers and transcription factors , while knockdown decreased the expression of these genes .Expectedly , Rspo2 overexpression also promotes SMC differentiation in vivo.
Mechanistically , our data showed that Rspo 2 could promote SRF binding to SM22 promoter region .Evidence also revealed that one of three Rspo2 receptors, LGR5, was up-regulated while the other two , LGR4 and LGR6, was down-regulated.Silencing of LGR5 inhibi-ted Rspo2-induced SMC differentiation, whereas knockdown of LGR4 had no impact.Finally, activation or inhibition of β-catenin could promote or inhibit SMC differentiation , respectively .CONCLUSION: Our findings demonstrate for the first time that Rspo 2 plays a positive role during smooth muscle cell differentiation from embryonic stem cells .We confirmed that Rspo 2 can up-regulate smooth muscle markers at transcription level .We also revealed Rspo promote smooth muscle cell differentiation through activation of LGR 5 re-ceptor and Wnt/β-catenin pathway .

低分化肺腺癌左上臂及背部肌内转移1例

肺癌晚期可出现各个不同脏器的转移而引起相应的症状,常常给患者带来极大的痛苦,甚至威胁到生命.肺癌转移主要以直接蔓延和淋巴结转移为主,晚期可发生血行转移.首发症状为软组织转移较少见,现对新疆医科大学第一附属医院诊治的1例低分化肺腺癌左上臂及背部肌内转移的病例报道如下.