Copper-induced skeletal myopathy in rabbits.

Doses of 1.66 mg Cu/kg/day, as cupric acetate in aqueous solution, were injected intramuscularly into the lateral thigh muscles of rabbits. The rate of loss of Cu from the injection site was estimated from in vivo measurements of 64Cu injected on the 15th day. Biological half-life values were 1.0 h for the first component (accounting for 65.2% of the 64 Cu) and 14.6 h for the second component (34.8% of the 64Cu). For the control group, values were 0.8 h and 62.2%, 14.6 h and 37.8%. Grossly visible lesions of dermatitis were noted on the paws, i.e. at sites removed from the site of injection, in some rabbits injected with Cu acetate two days post injectionem (p.i.). Histologically detectable lesions of acute inflammation were seen as early as 24 hours p.i. at the injection site of rabbits which had been exposed to the Cu once. Multiple injections and longer time periods resulted in lesions of acute and chronic inflammation. Cu was detected by the use of rubeanic acid stain. Signs of muscle degeneration and regeneration were seen as early as three days p.i. in rabbits which had received two injections of Cu. Rabbits which had been killed six days p.i. after a single injection showed chronic inflammatory changes and newly formed myofibres. Rabbits which had been killed 37 days p.i. after 17 injections showed lesions of acute and chronic inflammation of muscle and surrounding connective tissue, as well as signs of muscle regeneration. The gangrene visible grossly was attributed to the ischaemia caused by conglomerations of Cu.     

Incidence of sarcocysts in skeletal muscles of horses.

The incidence of sarcocysts was examined in postural, propulsive and respiratory muscles from 74 horses ranging in age from mid-gestation to 14 years post-natal. Cryostat sections were stained for myosin adenosine triphosphatase (ATPase) at pH 9.5 and the type of muscle fibre containing sarcocysts was identified. Sarcocysts were found in muscles from three animals, all aged 1 year or more. Counts showed that they displayed no preference for any particular muscle. However, fibres with a high activity for myosin ATPase were preferentially colonized. Transverse sectional profiles of sarcocysts showed a wide variation in size, shape and wall thickness. Both the proportion of horses infected and the intensity of infection per animal were considerably lower than those reported in other studies.     

Distribution of parvalbumin in specific fibre types of chicken skeletal muscles

1. The distribution of parvalbumin (PA), which functions as a relaxing factor in the skeletal muscles, was examined in slow anterior latissimus dorsi (ALD), fast posterior latissimus dorsi (PLD), mixed sartorius (SA), pectoralis superficialis (PS) and pectoralis profundus (PP) muscles from chickens.

2. The biochemical characteristics of these muscles were confirmed by the assay of total lactate dehydrogenase (LDH) activity as well as the LDH isozymes for anaerobic metabolism, and by the photometrical analysis of myoglobin for aerobic metabolism.

3. PA in individual muscles was determined by a sandwich ELISA and was demonstrated by 2‐dimensional polyacrylamide‐gel electrophoresis.

4. Because of poor myoglobin and higher LDH activity or M‐type isozyme pattern, the PLD was confirmed as containing primarily fast‐twitch glycolytic and oxidative‐glycolytic (FG/FOG) fibres, while the SA was shown to be composed mosdy of FOG fibres because of the highest myoglobin content and the intermediate LDH activity or H and M‐type isozyme pattern. PA content was high and variable in both PLD and SA.

5. PA was undetectable in the ALD which appears to contain exclusively slow‐tonic (ST) fibres, being verified by its myoglobin‐rich nature and lowest LDH activity or predominant H‐type isozyme characteristics. PA was absent from the PS and PP, which probably contain predominantly FG fibres because of negligible amounts of myoglobin and the highest LDH activities or M‐type isozyme pattern.     

骨骼肌琥珀酸脱氢酶的组织化学方法探讨

应用骨骼肌琥珀酸脱氢酶法检测哺乳动物骨骼肌的肌纤维型 ,在 1 95 7年首先由 Nachlas等 [1]创建色素形成四唑盐法 ,倍受各国学者的广泛青睐而加以普遍应用。经过四十多年来的改良和创新 ,为了迅速、方便地切实反映骨骼肌各型肌纤维间的分辨 ,提高肌纤维的区分度。利用镁离子作为酶的激活剂来激活骨骼肌细胞浆内线粒体中琥珀酸脱氢酶 ,在其脱氢作用下 ,含有双四唑盐的底物释放出氢原子 ,与无色的双四唑盐结合 ,还原形成蓝色的双甲月赞色素 ,沉着于酶作用的所在部位 ,据此分出染成蓝色的 型纤维和未染色的 型纤维。 1 96 8年 Pearse[2 ]发…     

Cimaterol reduces beta-adrenergic receptor density in rat skeletal muscles.

Interactions between the beta-adrenoceptor agonist cimaterol and beta-adrenoceptors on rat skeletal muscle membranes were examined in two studies. In Exp. 1, muscle samples from eight Sprague-Dawley rats (female, approximately 200 g) were used for competition binding and autoradiographic studies using [125I]cyanopindolol (ICYP) as a radioligand. The affinities or dissociation constants for binding (KD values) for cimaterol in plantaris and soleus muscles were .68 and .92 microM, respectively. Muscle areas stained for succinic dehydrogenase had propranolol-resistant ICYP binding sites; cimaterol did not seem to compete for these sites. In Exp. 2, 60 Sprague-Dawley rats (female, approximately 218 g) were fed 0 or 10 ppm of cimaterol in rat diet that was ground. Groups were killed after 1, 3, 7, 14, or 28 d of treatment. Cimaterol increased BW gain up to 14 d after commencement of treatment, with little or no improvement thereafter. Enhanced weight gain in skeletal muscles also occurred up to 14 d of cimaterol treatment. Densities of beta-adrenoceptors in plantaris and soleus muscle membrane homogenates were estimated using a radioligand binding assay with ICYP. A significant reduction in the number of binding sites (Bmax) was observed after 3 d of cimaterol treatment in plantaris muscle without a change in the KD of ICYP binding. The percentage reductions in Bmax were 26.8, 42.2, 37.7, and 37.8% at 3, 7, 14, and 28 d after cimaterol administration, respectively. In the soleus muscle, significant reductions (44.1 and 29.8%) in Bmax were observed after 3 and 14 d of cimaterol treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estimation of increased vascular permeability in the sheep skin

Extract

A cardinal feature of inflammation is the striking increase in the permeability of capillaries and venules to plasma protein. This is referred to as increased vascular permeability.     

The effect of cadmium poisoning on glucose transformation in skeletal muscles

Long-time effects of Cd on carbohydrate metabolism were investigated in male Wistar rats. A dose of 0.3 mg/kg body weight of Cd in acetate form was subcutaneously injected to the experimental animals twice a week through 3 months. Selected enzyme activities of glycolysis as well as concentrations of glycogen, glucose, pyruvate, lactate, triglycerides, and free fatty acids (FFA) were determined in blood serum, muscles, liver, and fatty tissues. The experimental animals differed from the control group, in that Cd intoxication was followed by decline in the blood serum only of pyruvate kinase and lactate dehydrogenase activities. In the liver, however, all enzyme activities were reduced. Glycogen glucose and FFA levels were increased. Intramuscular alterations were found to depend on the fibre type. The severest disturbance of glycolysis was recordable from red long fibres, whereas rapid white fibres were more resistant. The change in FFA concentration may be interpreted as some compensation for the impairment of carbohydrate metabolism in the energy balance.     

Myofiber differentiation in skeletal muscles of newborn runt and normal weight pigs

Differentiation of myofiber types and proportions of secondary and primary myofibers were investigated in the deep semitendinosus and longissimus muscles of 12-h- and 3-d-old littermate runt and normal birth weight pigs. Runt pigs 12 h after birth had lower proportions of type I fibers in the deep semitendinosus than did normal size pigs, which indicates that in utero stunting delayed the normal differentiation of myofiber histochemical characteristics. More of the type I myofibers had centrally located nuclei in runt pigs than in normal birth weight pigs. Also, newborn runt pigs had lower ratios of secondary to primary myofibers in the deep semitendinosus. This result indicates that the restriction of prenatal myofiber hyperplasia probably had a greater effect on secondary than on primary myofiber formation. None of these differences were observed in the longissimus muscle.     

Histochemical changes in skeletal muscles of four male horses with neuromuscular disease

Skeletal muscle biopsy specimens were taken from 4 male horses with neuromuscular disease such as myotonia congenita, chronic myositis, exertional rhabdomyolysis, and shivers. Histologic and histochemical techniques were used to evaluate skeletal muscle morphologic features and fiber-type population, size, and area, as well as muscle enzyme activities (acid phosphatase, alkaline phosphatase, and esterase). A histochemical and histologic profile were described for each muscle biopsy specimen.     

Sustained strenuous exercise increases intestinal permeability in racing Alaskan sled dogs

We assessed gastric and intestinal permeability and performed gastroscopy to evaluate the effects of sustained strenuous exercise on the gastrointestinal tract in racing sled dogs. Three teams of racing Alaskan sled dogs were examined approximately 1 week before and 24 hours after the 2003 Iditarod sled dog race (1,100 miles in 10 days). Each examination consisted of the administration of a solution of sucrose, lactulose, and rhamnose to evaluate gastric and intestinal permeability, as well as gastroscopy to visually inspect the gastric mucosa. Of the 54 dogs examined before the race, 16 completed the course and contributed data to the analysis. Sustained strenuous exercise was associated with an increased frequency of gastric erosions or ulcerations seen endoscopically (0% prerace versus 61% postrace). A significant postrace increase occurred in the median lactulose to rhamnose ratio in both serum and urine (0.11 versus 0.165, P = .0363; 0.11 versus 0.165, P = .0090, respectively). No significant differences were found in median serum or urinary sucrose concentrations when pre- and postrace values were compared. No correlation was found between visible gastric lesions and the concentration of sucrose in serum or urine samples obtained 4-5 hours after administration of the sugar solutions. We conclude that sustained strenuous exercise is associated with increased intestinal permeability, but the sucrose permeability test as we performed it did not correlate with visible gastric lesions.     

母体营养对后代肌肉生长发育的影响

骨骼肌占机体干重的50%以上,是机体的重要组成部分。肌肉的发育受很多因素的调控,而在关键窗口期,母体营养对其影响是至关重要的。母体营养状况可以改变后代肌纤维的数目、密度、肌肉的代谢、胰岛素敏感性和肌内脂肪的沉积。本文就母体营养对后代肌肉发育的影响作一简要概述。