Ragged-red fibres detected in paraffin sections by a monoclonal antibody to inner mitochondrial membrane

Summary An immunohistochemical method is reported using the M-II68 monoclonal antibody, which detects mitochondrial accumulations (ragged-red fibres) in routinely processed (formalin-fixed, paraffin-embedded) muscle tissue. Ten cases with electron-microscopically and histochemically proven mitochondrial myopathy featured 4% to 24% ragged-red fibres. In a series of 50 muscle biopsies without mitochondrial myopathy, scattered ragged-red fibres (<0.1%) were present in a few normal and pathological muscles. The immunohistochemical method is specific for mitochondria, does not require frozen tissue and permits rapid examination of large areas. Present address and address for offprint requests: Ludwig-Boltzmann-Institut für Klinische Neurobiologie, Krankenhaus Lainz, Wolkersbergenstrasse, A-1130 Wien. Austria     

Glycogenosomes in fibres of human normal skeletal muscles

Summary Analysis of muscle biopsies from five patients, with no clinical evidence of neuromuscular disorders, showed the presence of membrane-bound structures containing glycogen (glycogenosomes). Occurrence of these structures within human muscle fibres has been usually considered a pathological finding, common to various types of metabolic diseases. Our results provide evidence that glycogenosomes are a normal constituent of human muscle fibre, thereby emphasizing that any relationship between glycogenosomes and a specific pathological condition should be established with great care.Supported by a grant from CDCH of UCV (no. C-01.3/82)     

Changes in human skeletal muscles due to ageing

Summary Morphological changes in human skeletal muscle with ageing are reported. Samples from the deltoid and the vastus lateralis muscles from 126 subjects, aged 20–80 years, were studied by light microscopy. The patients died suddenly due to accidents or from fatal diseases. Until their death, they had preserved normal physical activity corresponding to their age. Chronic diseases, inactivity or neuromuscular diseases which are known to lead to changes in the muscles were excluded. The frequency of neurogenic changes of muscles increased with increasing age. These results correlated with electrophysiological and morphological changes in the peripheral nerves due to ageing reported by other investigators. The neurogenic changes in persons over 70 years were overlapped by a type-2 fibre atrophy.Supported by the Ministry of Public Health of the German Democratic Republic (HFR Schwangerschaft und frühkindliche Entwicklung, FR Genetische Defekte)     

微波热凝后骨骼肌体积及功能的变化

背景：微波利用其热效应在医学领域得到广泛应用,经微波热凝作用后造成局部组织凝固性坏死,坏死部位由纤维组织修复。但是微波热凝是否能产生缩容效果运用于口腔临床,目前经检索国内外尚未见报道。目的：观察微波热凝骨骼肌后肌肉体积和功能的改变,探讨微波热凝用于骨骼肌体积缩小的可能性。　方法：20 只新西兰大白兔暴露双侧胫骨前肌,采用2 450 MHz微波治疗仪以70 W微波热凝一侧胫骨前肌20 s,另一侧不做微波热凝作对照。分别于热凝后24,48 h和1,8周,随机各处死5只兔,测量双侧胫前肌体积变化,8周处死动物前,行肌电生理检测双侧胫前肌的肌动力。　结果与结论：微波热凝后24,48 h骨骼肌体积增大[(5.82±0.93),(6.04±0.47) mL],48 h体积最大,1周后肌肉体积开始缩小[(4.90±0.80) mL],8周后体积[(4.27±0.67) mL]缩小23.6%;肌电生理检测显示对照组与热凝组潜伏期分别为(1.765±0.393),(1.760±0.394) ms,波宽分别为(6.273±0.808),(6.259±0.773) ms,两组之间传导速度及波宽差异无显著性意义(P > 0.05)。结果证实微波热凝后48 h内肌肉体积增大,随后体积减小,骨骼肌可保持肌功能。     

Muscle phosphofructokinase deficiency in a myopathic child with severe mental retardation and aplasia of cerebellar vermis

Muscle phosphofructokinase (PFK) deficiency in man is responsible for at least two forms of myopathy; one is characterized by painful contractures of muscles and typically occurs in adults, whereas the other is often disabling and typically occurs in childhood, with psychomotor and growth retardation. In this investigation, a young myopathic patient with severe mental retardation and aplasia of the cerebellar vermis presented with muscular hypotrophy of the limbs, generalized hypotonia, convergent strabismus and marked pain during passive movement. Biopsy of quadriceps femoris muscle showed variation in the fiber size with sarcoplasmic areas positive for periodic acid-Schiff stain. Histochemical qualitative reaction for PFK showed no staining of muscle fibers; ultrastructural studies showed abnormal accumulation of glycogen granules in both intermyofibrillar and subsarcolemmal areas. While some enzyme activities in the muscular crude extract were significantly lower than in controls, direct assay of PFK revealed no activity, thus demonstrating that the child's myopathy was due to the lack of PFK activity.     

Changes in skeletal muscles of young women with anorexia nervosa

Summary Biopsies from four young women with advanced anorexia nervosa were examined to investigate the effect of malnutrition on skeletal muscles. None of the patients showed signs of neuromuscular disease and all were physically active at the time of examination.Cryostat sections from the vastus lateralis muscle were stained with hematoxylin-azophloxin-safran and with stains for myofibrillar ATP-ase activity. In addition to routine examination of the sections, the size and distribution of the type 1 and type 2 fibres were calculated by means of a Kontron Digiplan MOP 02.Routine stained sections showed a small grouped atrophy in three cases and a more diffuse atrophy in the fourth. Enzyme histochemical stains revealed a distinct type 2 atrophy, a finding which should serve to distinguish the changes of pure malnutrition from those of conventional denervation.Exact measurements confirmed the predominant type 2 atrophy but showed definite atrophy also of the type 1 fibres. Compared with normal controls the type 1 fibres were reduced by 46% and the type 2 fibres by 75%. These findings are largely in agreement with the recent observations by Essén et al. (1981) on anorexia nervosa. However, in contrast to Essén et al. we did not find any change in the numerical distribution of the fibre types, especially no increase in type 1 fibres. Thus, we could not confirm the hypotheses of a conversion of the fibre types in cachexia.     

Humanin detected in skeletal muscles of MELAS patients: a possible new therapeutic agent

Humanin (HN) was originally identified as an endogenous peptide that protects neuronal cells from apoptosis induced by various types of Alzheimers disease-related insults. We have previously indicated that HN increases cellular ATP levels and speculated that this peptide may rescue energy-deficient cells in mitochondrial disorders. Here, we report, for the first time, increased HN expression in skeletal muscles from patients with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS). HN was strongly positive in all ragged-red fibers (RRFs) and some non-RRFs, and most of them were type 1 fibers generally requiring higher energy than type 2 fibers. HN in these fibers was localized in mitochondria. HN expression was also increased in small arteries that strongly reacted for succinate dehydrogenase. Our experiments on muscular TE671 cells indicated the possibility that synthesized HN increases cellular ATP levels by directly acting on mitochondria. From these in vivo and in vitro findings, we propose that HN expression might be induced in response to the energy crisis within affected fibers and vessels in MELAS muscles and further be a possible therapeutic candidate for MELAS.     

Quantitative analysis of the size distribution of target-and targetoid fibres employing the method of daeves and beckel for mixed distributions

Summary An analysis of frequency distribution is performed in 250 target and targetoid fibres each from the anterior tibial muscle of a case with rapidly proceeding denervation atrophy. Following plane measurements on cross sections the size data were analysed according to the method of Daeves and Beckel [1] for mixed distributions. Three homogeneous normally distributed populations could thus be extracted from the mixed distributed sample. The largest population represents target fibres with a normal size range, while the second one encloses hypertrophic fibres, and the third and smallest one consists of fibres ranging within atrophic size limits. These findings support the previous presumption that targets predominantly occur in fibres of normal size and can therefore be regarded as manifestations of an early stage of denervation atrophy. The targetoid fibres, on the contrary, are of an atrophic size by 84%, while only a small population of about 15% contains targetoid fibres of a normal size on cross section.     

3H]Ouabain binding in normal and dystrophic mouse skeletal muscles and the effect of age

The numbers of Na+-K+ ATPase sites in skeletal muscles of normal and dystrophic mice between 3 and 17 months of age have been estimated using [3H]ouabain binding assays. In normal mice, at all ages, slow twitch muscle, soleus (SOL), bound significantly more [3H]ouabain than fast-twitch muscle, extensor digitorum longus (EDL). [3H]Ouabain binding did not alter in either SOL or EDL from normal mice over the age range studied. The numbers of Na+-K+ ATPase sites did alter in muscles taken from dystrophic mice (C57BL/6J dy2J/dy2J). In EDL there was an increase and in SOL a decrease in [3H]ouabain binding. This may be related to a change in muscle fibre metabolism from glycolytic to oxidative or to an altered activity pattern. Increasing age resulted in a progressive reduction in [3H]ouabain binding of both SOL and EDL from dystrophic mice. Part of this reduction may be only apparent and due to an increase in connective tissue composition of dystrophic muscles. A limited study of muscles from neonate dystrophic mice indicated that abnormal [3H]ouabain binding was not present in EDL before two weeks of age.     

Putative nociceptor responses to mechanical and chemical stimulation in skeletal muscles of the chicken leg

Electrophysiological responses of nociceptive sensory afferent fibres in the skeletal muscle of the chicken (Gallus domesticus) were examined using mechanical and chemical stimulation. The activity of single nociceptive afferent fibres was recorded from micro-dissected filaments of the fibular and lateral tibial nerves, which innervate the fibularis longus and lateral gastrocnemius muscles. Seventeen putative nociceptive fibres were identified by mechanical stimulation (muscle compression). Conduction velocities (CVs) ranged from 2.8 to 11.3 m/s (mean 5.8; S.E.M.±0.9 m/s). Response thresholds to tissue compression ranged from 38 to 126 kPa (mean 81; S.E.M.±4 kPa). Increases in pressure intensity, above individual fibre thresholds (×2 moderate; ×3 noxious), produced intensity dependent increases in discharge rates. Fibres exhibited slowly adapting, irregular discharges lasting the duration of the stimulus and showed no spontaneous activity in the absence of mechanical stimulation. Intramuscular injection of acetic acid (1% v/v in isotonic saline; pH 2.8) in to the receptive field area stimulated discharge activity in 13 of the 17 (76%) pressure sensitive fibres. Acid injection resulted in prolonged irregular single or intermittent clustered discharges, which continued beyond the 15-min recording period. This study demonstrates the existence of nociceptive sensory fibres in chicken skeletal muscle that are able to respond to and encode acute tissue threatening and subjectively painful stimuli. The physiological characteristics of these nociceptive afferents are consistent with mammalian group III skeletal muscle nociceptors. These findings support the suggestion of a common, acute nociceptive response function in skeletal muscle in avians and other vertebrate classes.     

Regulatory mechanism of the ventromedial hypothalamus in enhancing glucose uptake in skeletal muscles

To evaluate roles of the sympathetic nervous system in enhancing glucose uptake in skeletal muscles in response to electrical stimulation of the ventromedial hypothalamic nucleus (VMH), the effects of guanethidine treatment and adrenal demedullation on the response were examined in rats anesthetized and injected with muscle relaxant, pancuronium bromide. Pretreatment with guanethidine effectively suppressed the increase in the rate constant of glucose uptake, measured by the 2-deoxy-d-[³H]glucose method, in skeletal muscles upon VMH stimulation. However, bilateral adrenodemedullation had no significant effect. These results suggest that the VMH is intimately concerned in the regulation of glucose uptake in skeletal muscles through intermediation of the sympathetic nerves.     

Heroin-induced myopathy in rat skeletal muscle

Summary The effects of heroin on rat skeletal muscle was studied. Heroin was injected intraperitoneally, and the soleus and tibial anterior muscles were studied using histological and histochemical techniques. Degenerative and regenerative changes were detected, the latter proving more significant. The soleus was the only muscle affected, the anterior tibial showing no sign of damage. The heroin myopathy model may be valuable in studying muscle fibre necrosis and regeneration.     

Nucleo-cytoplasmic ratio in ageing skeletal muscle

Summary In order to investigate possible changes in the nucleo-cytoplasmic ratio of the muscle fibres during ageing, samples of quadriceps femoris from 15 normal individuals whose age ranged from 17 to 82 years were studied (autopsy material). The mean lesser diameter and the number and size of the muscle fibre nuclei were calculated using a planimetric technique. It was found that nucleo-cytoplasmic ratio increased significantly after the age of 60 years. This was due to a decrease in the mean fibre size whilst the number and the size of myonuclei remained unchanged. The resemblance of this finding to denervation atrophy changes is noted.     

Contrasting histochemical features of various mitochondrial syndromes

A comparative histochemical analysis of the prevalence and cytochrome oxidase staining characteristics of ragged-red fibres in limb skeletal muscles was performed in 19 patients spanning four distinct mitochondrial syndromes: chronic progressive external ophthalmoplegia; myoclonus epilepsy with ragged-red fibres; mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes; and pure limb myopathy. The percentage occurrence of non-ragged red but cytochrome oxidase negative fibres was additionally noted. Ragged-red fibres and cytochrome oxidase-negative fibres were generally more prevalent in the chronic progressive external ophthalmoplegia syndrome than in myoclonus epilepsy ragged-red fibres syndrome or mitochondrial myopathy encephalopathy lactic acidosis and stroke-like episodes syndrome. Isolated cytochrome oxidase-negative fibres were a common finding in each phenotypic syndrome except pure limb myopathy and could involve any of the major fibre types non-specifically. Ragged-red fibres were devoid of cytochrome oxidase activity in chronic progressive external ophthalmoplegia, but commonly displayed activity in the other three syndromes providing a clue to syndromal differentiation on a histochemical basis.     

Site-dependent pathological differences in smooth muscles and skeletal muscles of the adult MDX mouse

This study presents a survey of the morphometric characteristics, the regeneration rate, and the extent of muscle dystrophy in several smooth and skeletal muscles from adult mdx mice, an animal model of the Duchenne muscular dystrophy (DMD). Smooth muscles from adult mdx mice showed neither cell necrosis nor fibrosis. As compared to control C57 mice, the thickness of the mdx smooth muscle was normal in the vascular and urogenital layers but significantly reduced in the digestive layers, a finding relevant to clinical reports of gastrointestinal dilatation in DMD patients, and suggesting that gastrointestinal dysfunctions should be systemically searched for in DMD patients. Adult mdx skeletal muscles, however, presented different patterns of muscle suffering: either absent (esophagus); very mild (trunk and limb muscles); or severe (diaphragm). In these three conditions we studied the fiber diameters, the nuclei locations, and the regeneration rate. From this comparative study, it seems that severe dystrophy occurs in muscle tissues showing large fiber diameter and peripheral location of the nuclei. We showed that this combination occurs in the mouse diaphragm which is thus a realistic model for human DMD muscles. © 1995 John Wiley & Sons, Inc.     

Intramuscular nerves in motor neurone disease

Summary The ultrastructure of human intramuscular nerves at biopsy has been compared in motor neurone disease with that in other neuromuscular disease including muscular dystrophy and in controls. Myelinated axons appeared to be lost in control patients aged over 50 years, but this varied both between and within nerve fascicles. Even in two boys aged 31/2 and 9 years, but with Duchenne's dystrophy, examples were found of nerve fascicles with few or no axons. In motor neurone disease additional nerve fibres were lost, but there was little change in the size distributions of axons and myelin sheaths within the muscle. In both preterminal and terminal fascicles there was an increase of Schwann cell cytoplasm in association with unmyelinated axons, which was compatible with nerve sprouting. It is concluded that intramuscular nerves are likely to be lost with age as well as motor neurone disease. The results are discussed in relation to the stage of the disease process at biopsy.     

Peripheral nerve injury causes transient expression of MHC class I antigens in rat motor neurons and skeletal muscles

After a peripheral nerve lesion (rat facial and sciatic) an induction of major histocompatibility complex (MHC) antigens class I was detected immunohistochemically in skeletal muscle fibers and motor neurons. This MHC expression was transient after a nerve crush, when regeneration occurred, but persisted after a nerve cut, when regeneration was prevented. Since the time course of MHC class I expression correlates to that of regeneration a role for this cell surface molecule in regeneration may be considered.     

Asymmetric molecular forms of acetylcholinesterase in mammalian skeletal muscles

Velocity sedimentation analysis of acetylcholinesterase (AChE) molecular forms was performed separately in endplate-rich and endplate-free regions of the diaphargm muscle of the rat, guinea pig, rabbit, dog, and pig, and in mm. erectores trunci and m. vastus lateralis in man. Several high-ionic-strength media were first tested to achieve better solubilization of AChE from rat muscles than by the usual 1 M NaCl- Triton X-100 medium. Ninety-five percent of the rat diaphragm was solubilized in a single extraction step by medium containing 1 M lithium chloride instead of NaCl. Homologous molecular forms of AChE were found in all species. The asymmetric forms were invariably present in the endplate regions of muscles but their activity in endplate-free regions was much lower than in endplate regions in all investigated mammals except in man. Essentially the same pattern of AChE molecular forms was present in both regions in human muscles. High extrajunctional activity of the asymmetric forms makes human muscles similar to immature rodent muscles in vivo and in culture. The pattern of AChE molecular forms in the endplate region of the diaphragm in senile 24-month-old rats was not significantly different from that in 3-month-old animals. The persistence of the asymmetric AChE forms in the diaphragm of senile rats suggests that neuromuscular interactions do not become deficient with age in this muscle.