Histochemical studies on striated muscle fibres of the beige mutant mouse

A histological study of cylindric structures in skeletal muscle fibres from beige mice with the Chediak-Higashi syndrome was carried out. The muscle tissue was investigated morphologically with a differential interference contrast microscope and stained for glycogen, lipid, and basophile elements. It is suggested that the cylindric structures represent accumulations of glycogen rich lipoprotein membranes.     

Histochemical changes in striated muscle in patients with intermittent claudication

Biopsy specimens from the gastrocnemius or rectus femoris muscle of 20 patients with intermittent claudication were studied using fresh frozen cryostat sections and histochemical reactions for adenosine triphosphatase, nicotinamide adenine nucleotide dehydrogenase reductase and phosphorylase and modified Gomori trichrome staining. Neuropathic changes, such as fibertype grouping and small group atrophy, were present to some extent in all of the biopsy specimens. Myogenic muscle changes such as necrosis and phagocytosis were seen in approximately one third and various forms of myofibrillar disorganization in approximately two thirds of the specimens. The amount and size of the type I aerobic fibers increased with the increasing severity of the ischemic disease.     

急性下肢动脉缺血程度分级相关因素探讨

目的探讨影响急性下肢动脉缺血分级的相关因素。方法回顾性分析笔者2005年5月至2010年6月收治的73例经造影证实为急性下肢动脉栓塞或急性下肢动脉血栓形成的患者,其中男性40例,女性33例;年龄35~90岁,平均年龄68.5岁。采集临床相关资料,对性别、年龄、缺血时间、吸烟史、其他合并症、肢体动脉栓塞史、梗阻原因(栓塞/血栓形成)等可能影响急性缺血分级的因素,使用SPSS 11.5软件进行多因素逻辑回归分析。结果该组患者73例,79条患肢,急性缺血分级:Ⅰ级2例(3条患肢);Ⅱ级65例,其中Ⅱa级32例(34条患肢),Ⅱb级33例(36条患肢);Ⅲ级6例(6条患肢)。缺血时间、糖尿病及梗阻性质可影响患者缺血程度(P<0.05)。随着缺血时间的延长,缺血程度逐渐加重;糖尿病患者下肢缺血程度倾向于Ⅱa级以下;急性动脉血栓形成缺血程度倾向于Ⅱa级,急性动脉栓塞缺血程度更趋向于Ⅱb级。结论缺血时间、糖尿病及梗阻性质与急性肢体缺血分级有相关性。     

Cryo-electron microscopic studies of relaxed striated muscle thick filaments

Summary Electron micrograph images of rapidly frozen suspensions of thick filaments from four different muscle types are presented. Their optical and computer transforms are compared with images and diffraction patterns of negatively stained filaments and with X-ray data from the same muscles. We conclude that myosin head arrangement can be preserved on rapid freezing and that the images produced can be analysed by image processing techniques to give new information on thick filament structure.     

Nerve conduction studies of lower extremities in pes planus subjects.

Pes planus is a condition in which the medial longitudinal arch is depressed. Pedoscop, eyeball visualization, ink mat and roentgenography were used in clinical evaluation. We performed nerve conduction studies on both feet of 28 pes planus subjects. Our results demonstrated mild prolongation distal latency of the medial and lateral plantar sensory nerves, and delayed sensory conduction velocity of the medial plantar sensory nerve. The presence of electrodiagnostic abnormalities in this study population helps to substantiate the presence of compression neuropathy of the medial or lateral plantar nerve in pes planus subjects.     

Radioautographic studies of glycogen synthesis in the striated muscle of rat tongue

Glycogen synthesis was studied in rat tongue striated muscle after administration of ³H-glucose using light and electron microscope radioautography. Neither fasting nor addition of unlabeled glucose were needed to produce incorporation of ³H-glucose into glycogen, the only radioactive substance found in the tissue. Intense radioautographic reactions indicating glycogen synthesis were already seen 20 minutes after injection and were preferentially located over glycogen accumulations in the intermyofibrillar spaces. A striking variation of silver grain density from fiber to fiber, was a somewhat unexpected finding in a muscle consisting of fibers of uniform metabolic type. Decrease in grain counts at the 90-minute interval suggested a rapid turnover of muscle glycogen. In agreement with this, there were no morphological signs of glycogen accumulation on glucose administration. PA-Schiff staining, as well as the number of glycogen granules in electron micrographs, did not increase, nor did granule diameters change significantly during the experiment. Electron microscope radioautographs showed all silver grains to be located over or very near glycogen granules and sarcoplasmic spaces. While all newly-formed glycogen seemed associated with preexisting granules, there was no evidence for the participation of the sarcoplasmic reticulum in glycogen synthesis.     

氟伐他汀对兔心肌缺血再灌注损伤的防治效应

目的：观察氟伐他汀对心肌缺血再灌注损伤的防治作用及对心肌ICAM-1 mRNA表达的影响。 方法： 24只日本大耳白兔，随机分3组，假手术组、对照组、处理组（给予氟伐他汀10 mg·kg－1·d－1喂服1周）,所有动物在手术前检测血脂，对照组和处理组复制缺血再灌注模型，假手术组只穿线不结扎。监测血流动力学指标，检测血清乳酸脱氢酶（LDH）和肌酸激酶（CK）的活性。RT-PCR检测缺血区及假手术组对应区域心肌ICAM-1 mRNA的表达。 结果： 各组动物在手术前1 d血脂指标无统计学差异；缺血开始后处理组各时点左室舒张末压（LVEDP）小于对照组（P＜0.05），左室内压变化最大速率（±dp/dtmax）大于对照组（P＜0.05）；他汀组LDH-1、CK、CKMB活性均显著小于对照组（均为P＜0.01)；他汀组心肌组织ICAM-1 mRNA表达显著低于对照组(P<0.01),假手术组表达最少。 结论： 氟伐他汀预处理能减轻心肌缺血再灌注损伤，其机制可能与抑制炎症反应有关。     

Tumors of striated muscle.

Three benign forms of muscle tumors and three variants of rhabdomyosarcoma are discussed from the point of view of their histology and behabior. Recent combined modality therapy has significantly improved the prognosis in at least the embryonal form of rhabdomyosarcoma.     

Basophilic degeneration of skeletal muscle in hypothyroid myopathy. Histochemical and ultrastructural studies

Morphologic and histochemical studies of basophilic degeneration (BD) of skeletal muscle were performed on a 64-year-old woman with hypothyroid myopathy. The BD had staining characteristics of polysaccharide and similarity to the deposits described in cardiac muscle in five of six muscle groups studied and was absent in the diaphragm. The frequent occurrence of BD at the myotendinous junction suggested the necessity of including this area in muscle biopsy specimens of suspected hypothyroid myopathy. Review of the literature indicated a need for more detailed examination of muscle specimens of these patients to determine the clinical implication and biochemical nature of the BD. To my knowledge, the demonstration of a close association of BD and leptomeres and the presence of crystalline structures within the BD have not been described previously.     

Phosphorylation of tropomyosin in striated muscle

An historical perspective of the phosphorylation of tropomyosin is provided. The effects of this covalent modification on the properties of striated muscle tropomyosin are summarised. Technical hurdles and findings in other systems are also discussed.     

The ultrastructure of striated muscle.

Striated muscle is a tissue in which the major cytoplasmic components are spatially arranged to produce directional motion. This orientation is seen at all levels of structure, beginning with the molecular placement of characteristic proteins into 2 dissimilar types of filaments, and proceeding ultimately to the alignment of muscle fibers in the heart or an anatomically defined skeletal muscle. Generation of contractile force is accomplished by the enzymatic interaction of the 2 dissimilar protein filaments, which results ultimately in the utilization of energy (in the form of adenosine triphosphate) and the production of directional motion.     

Regulation of contraction in striated muscle

Ca(2+) regulation of contraction in vertebrate striated muscle is exerted primarily through effects on the thin filament, which regulate strong cross-bridge binding to actin. Structural and biochemical studies suggest that the position of tropomyosin (Tm) and troponin (Tn) on the thin filament determines the interaction of myosin with the binding sites on actin. These binding sites can be characterized as blocked (unable to bind to cross bridges), closed (able to weakly bind cross bridges), or open (able to bind cross bridges so that they subsequently isomerize to become strongly bound and release ATP hydrolysis products). Flexibility of the Tm may allow variability in actin (A) affinity for myosin along the thin filament other than through a single 7 actin:1 tropomyosin:1 troponin (A(7)TmTn) regulatory unit. Tm position on the actin filament is regulated by the occupancy of NH-terminal Ca(2+) binding sites on TnC, conformational changes resulting from Ca(2+) binding, and changes in the interactions among Tn, Tm, and actin and as well as by strong S1 binding to actin. Ca(2+) binding to TnC enhances TnC-TnI interaction, weakens TnI attachment to its binding sites on 1-2 actins of the regulatory unit, increases Tm movement over the actin surface, and exposes myosin-binding sites on actin previously blocked by Tm. Adjacent Tm are coupled in their overlap regions where Tm movement is also controlled by interactions with TnT. TnT also interacts with TnC-TnI in a Ca(2+)-dependent manner. All these interactions may vary with the different protein isoforms. The movement of Tm over the actin surface increases the "open" probability of myosin binding sites on actins so that some are in the open configuration available for myosin binding and cross-bridge isomerization to strong binding, force-producing states. In skeletal muscle, strong binding of cycling cross bridges promotes additional Tm movement. This movement effectively stabilizes Tm in the open position and allows cooperative activation of additional actins in that and possibly neighboring A(7)TmTn regulatory units. The structural and biochemical findings support the physiological observations of steady-state and transient mechanical behavior. Physiological studies suggest the following. 1) Ca(2+) binding to Tn/Tm exposes sites on actin to which myosin can bind. 2) Ca(2+) regulates the strong binding of M.ADP.P(i) to actin, which precedes the production of force (and/or shortening) and release of hydrolysis products. 3) The initial rate of force development depends mostly on the extent of Ca(2+) activation of the thin filament and myosin kinetic properties but depends little on the initial force level. 4) A small number of strongly attached cross bridges within an A(7)TmTn regulatory unit can activate the actins in one unit and perhaps those in neighboring units. This results in additional myosin binding and isomerization to strongly bound states and force production. 5) The rates of the product release steps per se (as indicated by the unloaded shortening velocity) early in shortening are largely independent of the extent of thin filament activation ([Ca(2+)]) beyond a given baseline level. However, with a greater extent of shortening, the rates depend on the activation level. 6) The cooperativity between neighboring regulatory units contributes to the activation by strong cross bridges of steady-state force but does not affect the rate of force development. 7) Strongly attached, cycling cross bridges can delay relaxation in skeletal muscle in a cooperative manner. 8) Strongly attached and cycling cross bridges can enhance Ca(2+) binding to cardiac TnC, but influence skeletal TnC to a lesser extent. 9) Different Tn subunit isoforms can modulate the cross-bridge detachment rate as shown by studies with mutant regulatory proteins in myotubes and in in vitro motility assays. (ABSTRACT TRUNCATED)     

Heterotopic striated muscle on the surface of the brain

Summary Heterotopic tissue, identified by both light and electron microscopy as cardiac muscle, was detected at autopsy on the surface of the right superior temporal gyrus of a 73-year old female patient. The cells of the heterotopic tissue were interconnected by intercalated discs and the fibres contained regularly cross-striated, contracted, or relaxed myofibrils indicating a continuing contractile activity until the time of death.     

短期运动对大鼠缺血/再灌注心肌的保护作用

目的研究短期中等强度运动训练对大鼠缺血/再灌注(I/R)心肌的保护作用及与蛋白激酶C(PKC)激活的相关性。方法40只Wistar大鼠随机分为4组(每组10只):对照组(CON组)、运动组(EXE组)、运动 PKC抑制剂组(E C组)和PKC抑制剂组(CHE组)。应用Langendorff离体心脏I/R模型,观察各组大鼠心脏再灌注期间心律失常的发生情况、心功能指标恢复率及心肌梗死范围。结果EXE组大鼠LVDP(再灌注30、60 min)和RPP(再灌注20、30、60 min)恢复率高于CON和E C组(P<0.05或P<0.01),心肌梗死范围显著低于CON和E C组(P<0.01)。CON、CHE组上述各指标无差异。结论短期中等强度运动训练对I/R心肌有保护作用,保护作用与PKC的激活有关。