Alterations In Muscle Tissue Research Articles

The atorvastatin metabolite pattern in muscle tissue and blood plasma is associated with statin muscle side effects in patients with coronary heart disease; An exploratory case-control study

Background and aimsStatin-associated muscle symptoms (SAMS) is a prevalent cause of statin discontinuation. It is challenging and time-consuming for clinicians to assess whether symptoms are caused by the statin or not, and diagnostic biomarkers are requested. Atorvastatin metabolites have been associated with SAMS. We aimed to compare atorvastatin pharmacokinetics between coronary heart disease (CHD) patients with and without clinically statin intolerance and statin-dependent histopathological alterations in muscle tissue. Secondarily we aimed to assess genetic variants relevant for the observed pharmacokinetic variables. MethodsTwenty-eight patients with CHD and subjective SAMS were included in the exploratory MUSE biomarker study in 2020. Participants received atorvastatin 40 mg/day for seven weeks followed by no statins for eight weeks. Muscle biopsies and blood were collected at the end of each period. Four patients were categorized as clinically intolerant to ≥3 statins prior to study start whereas four patients had signs of muscle cell damage during treatment. ResultsWe found significantly lower levels of atorvastatin acids, and higher lactone/acid ratios in the statin intolerant, both in muscle and plasma. With optimal cut-off, the combination of 2-OH-atorvastatin acid and the 2-OH-atorvastatin lactone/acid ratio provided sensitivity, specificity, and predictive values of 100 %. Patients with variants in UGT1A1 and UGT1A3 had higher lactone metabolite levels than those with wild type, both in muscle and plasma. ConclusionAtorvastatin metabolites appear promising as biomarkers for the identification of clinical statin intolerance in patients with self-perceived SAMS, but the findings have to be confirmed in larger studies.

Pre-breeding Diets in the Seahorse Hippocampus reidi: How Do They Affect Fatty Acid Profiles, Energetic Status and Histological Features in Newborn?

Seahorses (Hippocampus spp.) are exceptional marine species considering their reproductive patterns and other features. Due to the iconic characteristics of these fishes, aquarium trade, and research efforts have increased in the last years. Consequently, novel rearing techniques have been developed; however, there is a need for improvements on a series of issues, namely reproduction success enhancement. The tropical species Hippocampus reidi is the most traded seahorse but many aspects of breeding and its impact on the quality of neonates are still poorly understood. In the present study, we assessed the effects of two pre-breeding diets on newborn quality and viability considering biochemical characteristics, energetic status, and ultrastructural aspects of muscular tissue. During the whole pre-breeding season (5 months), the breeders were fed on one of the following diets: M0 (adult non-enriched Artemia) and M5 (adult non-enriched Artemia + mysidaceans). From the onset of the reproduction period, all breeders were fed for 6 months on diet M5. Breeding success and energetic status (ATP, total adenylic nucleotides, AEC, and NAD) of newborns resulted considerably enhanced in treatment M5. However, initial differences in neonates quality did not affect further newborn performance (survival and growth until day 7 after male’s pouch release) while gaining access to high-quality preys (copepods). Besides, morphological alterations in muscle tissue were not observed. The reproduction in the species followed a capital–income continuum pattern characterized by an initial mixed capital-income period (until 70–100 days since the onset of the breeding season) followed by an income breeding period with progressive exhaustion of body reserves, especially in M0-newborns. Interestingly, the effects of pre-breeding diets were also noticed in the second half of the breeding period. Our results seemed to indicate that the requirements in essential fatty acids in H. reidi are lower than in other seahorse species (e.g., Hippocampus guttulatus). Globally, the results achieved revealed that high-quality pre-breeding diets enhanced reproduction success and would likely result advantageous to improve newborn endurance in conditions of moderate starvation or sub-optimal feeding.

Histological structure of skeletal muscle in disuse muscle atrophy and role of exercise

Disuse muscle atrophy is one of the most important research topics in fields of rehabilitation and clinical medicine. It refers to morphological and functional alteration of skeletal muscle under the states of hypokinesia, immobilization and weightlessness. This review analyzes a number of structural and functional changes in the skeletal muscle tissue in case of muscle disuse which appeared in loss in the muscle mass, reduction in the transverse diameter of most of muscle fibers, wide spaces between muscle fibers, increase collagen fiber deposition and appearance of apoptotic nuclei in muscle fibers besides sensorial dysfunction such as hypo mechanical responsiveness and diminished contractile function. In addition to the ultrastructural alteration, which include loss of sarcomere organization, indistinguishable A and I bands, irregular distorted Z-line with disruption of myofilaments and fused giant accumulated mitochondria. The review summarizes also the molecular mechanisms of skeletal muscle disuse atrophy which could be resulted from an alteration in the activity of oxidative stress enzymes and lead to increase in protein degradation and/or a reduction in protein synthesis. Moreover, the review discusses the efficiency of potential countermeasures of stretching exercise as a very powerful stimulant of muscle growth and muscle protein synthesis to counteract the structural and functional alterations in muscle tissue caused by disuse. The review showed that stretching exercise can increase the transverse sectional area of muscle fibers, produce a rise in the number of sarcomeres in series and prevent muscle atrophy. Passive stretching also completely prevented the decrease in myonuclear number induced by inactivity. Moreover, stretching accelerated the amelioration of the range of motion limitation and prevent the deposition of connective tissue resulted from disuse muscle atrophy.

Lake Edku pollutants induced biochemical and histopathological alterations in muscle tissues of Nile Tilapia (Oreochromis niloticus)

This study aimed to assess some water quality parameters of Lake Edku, evaluation of the effect of a complex mixture of contaminants on the fish biochemical composition, and the histopathological changes in muscle tissue of Nile Tilapia, Oreochromis niloticus inhabiting different locations of Lake Edku. Methods: Water samples and 200 fish of O. niloticus were collected from different regions of Lake Edku and transported to the laboratory. Fish were divided into three groups: El-Maadyah region, Edku drain, and the recovery (El-Maadyah region). Recovery fish were left in aquaria for a month. Water quality parameters including temperature, pH, dissolved oxygen, electrical conductivity, total dissolved solids, and salinity were measured. Muscle total protein, total lipid, energy value, moisture, and ash content were determined, and the histopathology of fish muscle was examined. A significant decrease of dissolved oxygen in the Edku drain region compared to El-Maadyah and the recovery groups was observed. The salinity value showed a significant increase in the El-Maadyah region compared to the other groups. On the other hand, Edku drain fish group exhibited a significant decrease in muscle total protein, energy value, and ash content compared to the other groups. In contrast, it exhibited an increase in the water content and a significant increase in total lipids compared to the other groups. The muscle sections of El-Maadyah and Edku drain fish revealed several alterations compared to the recovery fish including hyalinized and necrotic muscle fibers, vacuolar degeneration, parasitic granuloma, infiltration of macrophages, dispersed muscle fibers by edema, fatty tissue, a variable amount of connective tissue proliferation between bundles and glycogen granules. The results confirm that fish contaminated environment could result in the damage of muscle tissue and has negative impacts on the fish quality and its validation to human consumption.

Lipid alterations in the skeletal muscle tissues of mice after weight regain by feeding a high-fat diet using nanoflow ultrahigh performance liquid chromatography-tandem mass spectrometry

This study investigated lipid alterations in muscle tissues [gastrocnemius (Gas) and soleus (Sol)] of mice under different diet programs (weight gain, weight maintenance, weight regain, and controls) by nanoflow ultrahigh pressure liquid chromatography-electrospray ionization-tandem mass spectrometry. Since overloaded lipids in the skeletal muscle tissues by excessive fat accumulation are related to insulin resistance leading to type II diabetes mellitus, analysis of lipid alteration in muscle tissues with respect to high-fat diet (HFD) is important to understand obesity related diseases. A total of 345 individual lipid species were identified with their molecular structures, and 184 lipids were quantified by selected reaction monitoring method. Most triacylglycerol (TG) and phosphatidylethanolamine (PE) species displayed a significant (>2-fold, p < 0.01) increase in both the Gas and Sol and to a larger degree in the Gas. However, lipid classes involved in insulin resistance and anti-inflammatory response, including lysophosphatidylcholine (18:0), diacylglycerol (16:0_18:1, 16:0_18:2, and 18:1_18:1), ceramide (d18:1/24:0 and d18:1/24:1), and phosphatidylinositol (18:0/20:4), showed a significant accumulation in the Sol exclusively after HFD treatment. In addition, the lipid profiles were not significantly altered in mice that were fed HFD only for the last 4 weeks (weight gain group), suggesting that consuming HFD in the younger age period can be more effective in the Gas. This study reveals that lipid classes related to insulin resistance accumulated more in the Sol than in the Gas following HFD treatment and the weight regain program perturbed lipid profiles of the Sol to a greater extent than that by the other diet programs, confirming that the Sol tissue is more influenced by HFD than Gas.

Characterizing Woody Breast Myopathy in a Meat Broiler Line by Heat Production, Microbiota, and Plasma Metabolites.

Selection for quantitative traits in meat broilers such as breast yield and growth rate exert physiological pressure leading to ante mortem histological and biochemical alterations in muscle tissues. The poultry industry has recently witnessed a myopathy condition affecting Pectoralis major (breast muscle) of broilers, called woody breast (WB), an etiology still unclear to scientific community. A study was conducted to characterize the WB myopathy in a meat broiler line at its finishing phase (d 41) in terms of heat production (HP), microbiota and plasma metabolites. Two treatment groups were studied—WB affected (myopathy) and normal (non-myopathy) broiler; n = 20 in each group. Indirect calorimetry was utilized for HP measurement. Furthermore, body composition (BC) analysis was also performed using dual-energy x-ray absorptiometry (DEXA). Microbiota in ileal digesta was studied with PCR amplified 16s rRNA gene. LC-MS targeted metabolomics was performed to understand differential expression of plasma metabolites. Results showed that there was difference in fasting HP (P < 0.05) between these two treatment groups, with non-myopathy broiler producing more heat which was indicative of higher body protein content validated by higher protein: fat ratio by BC results. Less protein content in myopathy bird could be due to probable higher mixed muscle degradation occurring in lean tissue as marked by elevated 3-methylhistidine expression in plasma. Microbiota results showed unclassified Lactobacillus as predominant genus with higher abundance occurring in myopathy group; whereas at species level, L. acidipiscis was predominant bacteria for non-myopathy broiler. Differentially significant metabolites (P < 0.05) identified from plasma metabolome between these two treatment groups were homocysteine, cyclic GMP, trimethylamine N-oxide (TMAO), tyramine, carnitine, and acetylcarnitine, which were all associated to cardiovascular system. The findings suggest that more research in meat broilers could be opted toward delivering reduced vascularity issues to alleviate this myopathy condition.

Decreased Aerobic Exercise Capacity After Long-Term Remission From Cushing Syndrome: Exploration of Mechanisms.

BackgroundAlthough major improvements are achieved after cure of Cushing syndrome (CS), fatigue and decreased quality of life persist. This is the first study to measure aerobic exercise capacity in patients in remission of CS for more than 4 years in comparison with matched controls, and to investigate whether the reduction in exercise capacity is related to alterations in muscle tissue.MethodsSeventeen patients were included. A control individual, matched for sex, estrogen status, age, body mass index, smoking, ethnicity, and physical activity level was recruited for each patient. Maximal aerobic capacity (VO2peak) was assessed during incremental bicycle exercise to exhaustion. In 8 individually matched patients and controls, a percutaneous muscle biopsy was obtained and measures were made of cross-sectional areas, capillarization, and oxphos complex IV (COXIV) protein content as an indicator of mitochondrial content. Furthermore, protein content of endothelial nitric oxide synthase (eNOS) and eNOS phosphorylated on serine1177 and of the NAD(P)H-oxidase subunits NOX2, p47phox, and p67phox were measured in the microvascular endothelial layer.FindingsPatients showed a lower mean VO2peak (SD) (28.0 [7.0] vs 34.8 [7.9] ml O2/kg bw/min, P < .01), maximal workload (SD) (176 [49] vs 212 [67] watt, P = .01), and oxygen pulse (SD) (12.0 [3.7] vs 14.8 [4.2] ml/beat, P < .01) at VO2peak. No differences were seen in muscle fiber type–specific cross-sectional area, capillarization measures, mitochondrial content, and protein content of eNOS, eNOS-P-ser1177, NOX2, p47phox, and p67phox.InterpretationBecause differences in muscle fiber and microvascular outcome measures are not statistically significant, we hypothesize that cardiac dysfunction, seen in active CS, persists during remission and limits blood supply to muscles.

Muscle damage and inflammation during recovery from exercise.

Unaccustomed exercise consisting of eccentric (i.e., lengthening) muscle contractions often results in muscle damage characterized by ultrastructural alterations in muscle tissue, clinical signs, and symptoms (e.g., reduced muscle strength and range of motion, increased muscle soreness and swelling, efflux of myocellular proteins). The time course of recovery following exercise-induced muscle damage depends on the extent of initial muscle damage, which in turn is influenced by the intensity and duration of exercise, joint angle/muscle length, and muscle groups used during exercise. The effects of these factors on muscle strength, soreness, and swelling are well characterized. By contrast, much less is known about how they affect intramuscular inflammation and molecular aspects of muscle adaptation/remodeling. Although inflammation has historically been viewed as detrimental for recovery from exercise, it is now generally accepted that inflammatory responses, if tightly regulated, are integral to muscle repair and regeneration. Animal studies have revealed that various cell types, including neutrophils, macrophages, mast cells, eosinophils, CD8 and T-regulatory lymphocytes, fibro-adipogenic progenitors, and pericytes help to facilitate muscle tissue regeneration. However, more research is required to determine whether these cells respond to exercise-induced muscle damage. A large body of research has investigated the efficacy of physicotherapeutic, pharmacological, and nutritional interventions for reducing the signs and symptoms of exercise-induced muscle damage, with mixed results. More research is needed to examine if/how these treatments influence inflammation and muscle remodeling during recovery from exercise.

COMPARATIVE ANALYSIS OF BIOCHEMICAL PARAMETERS OF MUSCLE TISSUE ALTERATION DEPENDING ON APPROACHES FOR TOTAL HIP ARTHROPLASTY

The results of the comparative analysis of biochemical alterations of muscle tissue in the blood serum of patients who underwent primary total hip replacement. In this study, we consider the data of 75 patients who underwent total hip arthroplasty (75 operations) from November 2010 to April 2012 to analyze the data was divided into 3 groups of patients: the first - using a minimally invasive technique MIS AL (22 operations), the second - with the use of the modified approach Muller (pending on the invention) - (29 operations), and the third - with approach by Hardinge (26 operations). The levels of glutamic oxaloacetic transaminase, creatinine phosphokinase, lactate dehydrogenase, myoglobin, creatinine, and C-reactive proteine in serum were determined preoperatively and at 3, 5, 7, 9 days after surgery. CRP included in the study as an indicator of non-specific inflammation of the tissues. When comparing the biochemical indicators in three types of approaches to the hip joint, the highest increase in GOAT, LDH, CPK, CRP, and myoglobin was detected at surgery approach by Hardinge. The results of this study may indicate a decrease in the degree of tissue trauma during surgery using a minimally-invasive approaches, which is characterized by the retention of attachment to the middle gluteal muscle of the femur.

Quantification of muscular morphological alterations in patients with infantile and early-juvenile Pompe disease

Aims: Patients with infantile and early-juvenile Pompe disease (glycogen storage disease type II) show a variable degree of a vacuolar myopathy with pathological glycogen deposits in periodic acid-Schiff (PAS) stained sections. Enzyme replacement therapy (ERT) is available, but response to therapy is highly variable. The aim of this study was to develop a technique that allows quantifying morphological alterations in muscle tissue of Pompe patients.

Efectos de la sobredosificación con láser de arseniuro de galio sobre el cuádriceps de ratas

RESUMENObjetivo. Obtener información de los efectos de la irradiación con laser con el objeto de determinar dosis en la que se observen efectos deletéreos sobre el tejido muscular. Materiales y métodos. Se estudiaron 20 ratas macho Sprague Dawley y fueron divididas aleatoriamente en cuatro grupos de 5 individuos. En todos los grupos se realizó la irradiación con laser, empleando un equipo de diodo de Arseniuro de Galio. Se aplicó en forma puntual 1 vez al día durante 10 días consecutivos. El tiempo de exposición y las dosis diarias siguieron el siguiente arreglo: grupo A, 15 minutos y 24.3 julios, grupo B, 30 minutos y 48.6 Julios, grupo C, 45 minutos y 72.9 Julios, grupo D, 60 minutos y 97.2 Julios. Se tomaron muestras del cuadriceps para microscopía óptica y microscopía electrónica. Resultados. La microscopia óptica no mostró alteraciones en ninguno de los grupos estudiados. Al microscopio electrónico se observaron alteraciones ultraestructurales solamente en el grupo D. Conclusiones. El rango entre la dosis terapeútica y la que produce alteraciones ultraestructurales en el tejido muscular es tan amplio que hace del laser un eficiente elemento seguro para la terapia física.

Guanidine affects differentially the twitch response of diaphragm, extensor digitorum longus and soleus nerve-muscle preparations of mice.

Guanidine has been used with some success to treat myasthenia gravis and myasthenic syndrome because it increases acetylcholine release at nerve terminals through K+, Na+ and Ca2+ channels-involving mechanisms. Currently, guanidine derivatives have been proposed for treatment of several diseases. Studies aimed at providing new insights to the drug are relevant. Experimentally, guanidine (10 mM) induces on mouse phrenic nerve-diaphragm (PND) preparations neurotransmission facilitation followed by blockade and a greatest secondary facilitation after its removal from bath. Herein, we hypothesized that this peculiar triphasic response may differ in muscles with distinct twitch/metabolic characteristics. Morphological alterations and contractile response of PND, extensor digitorum longus (EDL) and soleus (SOL) preparations incubated with guanidine (10 mM) for 15, 30, 60 min were analyzed. Guanidine concentrations of 5 mM (for PND and EDL) and 1 mM (for EDL) were also tested. Guanidine triphasic effect was only observed on PND regardless the concentration. The morphological alterations in muscle tissue varied along time but did not impede the PND post-wash facilitation. Higher doses (20–25 mM) did not increase EDL or SOL neurotransmission. The data suggest a complex mechanism likely dependent on the metabolic/contractile muscle phenotype; muscle fiber types and density/type of ion channels, sarcoplasmic reticulum and mitochondria organization may have profound impact on the levels and isoform expression pattern of Ca2+ regulatory membrane proteins so reflecting regulation of calcium handling and contractile response in different types of muscle.

Clonus is explained from increased reflex gain and enlarged tissue viscoelasticity

Upper motor neuron diseases (UMND), such as stroke and spinal cord injury (SCI), are assumed to produce alterations in muscle tissue in association with neural damage. Distinguishing between these two factors is of clinical importance in choosing appropriate therapy. We studied the effect of changes in the gain of the Ia reflex pathway and tissue viscoelasticity on the emergence, frequency, and persistence of ankle clonus: a clinically significant, involuntary oscillatory movement disorder. Monte Carlo simulations were performed to explain our experimental observations in patients with stroke (n=3) and SCI (n=4) using a nonlinear antagonistic muscle model of the human ankle joint. Ia reflex gain was varied by changing motor unit pool threshold and gain, and passive tissue viscosity and elasticity were varied by changing optimal muscle length. Tissue viscoelasticity appeared to have a strong effect on the emergence and persistence of clonus. Observed frequencies of ankle movement, prior to and after the experimental intervention of a sudden damper, was predicted by the model. The simulations revealed that reflex gains were largest in patients with the largest tissue viscoelasticity. We conclude that ankle clonus in stroke and SCI is the result of a combination of, and suggests a relation between, (i) a decrease in threshold and an increase in gain of the motor unit pool and (ii) a decrease in optimal muscle length.

Evaluation of Functional and Structural Alterations in Muscle Tissue after Short-Term Cold Storage in a New Tissue Preservation Solution

Storage of muscle preparations in vitro is required for the diagnosis of neuromuscular disorders and for electrophysiological tests. The current standard protocols for muscle storage or transport, i.e. placement on 0.9% NaCl-moistened gauze, lead to impaired function and structural alterations. For other tissues, however, improved preservation methods and solutions have recently been described. In this study, functional and structural alterations in the murine diaphragm were compared after storage on 0.9% NaCl-moistened gauze and after storage in different modifications of the new vascular preservation solution TiProtec®. Muscle force generation after nerve stimulation, histological parameters and ATP levels were investigated after 2.5 h of cold storage at 4°C in the different media and 0.5 h of rewarming at 25°C in Tyrode buffer. Murine diaphragms were injured during cold storage and rewarming, with the degree of the alteration being dependent on the type of solution used. There were no histological alterations and no caspase 3 activation in all groups. In contrast, diaphragms stored in the modified TiProtec solution showed markedly better performance concerning force generation after nerve stimulation (7.1 ± 1.1 cN · s) as well as higher ATP content (2.4 ± 0.7 µmol/g) and were superior to storage on 0.9% NaCl-moistened gauze (1.4 ± 0.4 cN · s; 0.3 ± 0.1 µmol/g). In conclusion, the modified TiProtec preservation solution showed promising results for short-term cold storage of murine diaphragms. For further evaluation, the transferability of these positive findings to storage conditions for muscles of other species, especially human muscle tissue, needs to be investigated.

Sensory Ataxic Neuropathy in Golden Retriever Dogs Is Caused by a Deletion in the Mitochondrial tRNATyr Gene

Sensory ataxic neuropathy (SAN) is a recently identified neurological disorder in golden retrievers. Pedigree analysis revealed that all affected dogs belong to one maternal lineage, and a statistical analysis showed that the disorder has a mitochondrial origin. A one base pair deletion in the mitochondrial tRNATyr gene was identified at position 5304 in affected dogs after re-sequencing the complete mitochondrial genome of seven individuals. The deletion was not found among dogs representing 18 different breeds or in six wolves, ruling out this as a common polymorphism. The mutation could be traced back to a common ancestor of all affected dogs that lived in the 1970s. We used a quantitative oligonucleotide ligation assay to establish the degree of heteroplasmy in blood and tissue samples from affected dogs and controls. Affected dogs and their first to fourth degree relatives had 0–11% wild-type (wt) sequence, while more distant relatives ranged between 5% and 60% wt sequence and all unrelated golden retrievers had 100% wt sequence. Northern blot analysis showed that tRNATyr had a 10-fold lower steady-state level in affected dogs compared with controls. Four out of five affected dogs showed decreases in mitochondrial ATP production rates and respiratory chain enzyme activities together with morphological alterations in muscle tissue, resembling the changes reported in human mitochondrial pathology. Altogether, these results provide conclusive evidence that the deletion in the mitochondrial tRNATyr gene is the causative mutation for SAN.

A pilot study using Tissue Velocity Ultrasound Imaging (TVI) to assess muscle activity pattern in patients with chronic trapezius myalgia

BackgroundDifferent research techniques indicate alterations in muscle tissue and in neuromuscular control of aching muscles in patients with chronic localized pain. Ultrasound can be used for analysis of muscle tissue dynamics in clinical practice.AimThis study introduces a new muscle tissue sensitive ultrasound technique in order to provide a new methodology for providing a description of local muscle changes. This method is applied to investigate trapezius muscle tissue response – especially with respect to specific regional deformation and deformation rates – during concentric shoulder elevation in patients with chronic trapezius myalgia and healthy controls before and after pain provocation.MethodsPatients with trapezius myalgia and healthy controls were analyzed using an ultrasound system equipped with tissue velocity imaging (TVI). The patients performed a standardized 3-cm concentric shoulder elevation before and after pain provocation/exercise at a standardized elevation tempo (30 bpm). A standardized region of interest (ROI), an ellipsis with a size that captures the upper and lower fascia of the trapezius muscle (4 cm width) at rest, was placed in the first frame of the loop registration of the elevation. The ROI was re-anchored frame by frame following the same anatomical landmark in the basal fascia during all frames of the concentric phase. In cardiac measurement, tissue velocities are measured in the axial projection towards and against the probe where red colour represents shortening and red lengthening. In the case of measuring the trapezius muscle, tissue deformation measurements are made orthogonally, thus, indirectly. Based on the assumption of muscle volume incompressibility, blue represents tissue contraction and red relaxation. Within the ROI, two variables were calculated as a function of time: deformation and deformation rate. Hereafter, max, mean, and quadratic mean values (RMS) of each variable were calculated and compared before and after pain provocation/exercise.ResultsThis new methodology seems valuable when looking at local muscle changes and studying the mechanism behind chronic muscle pain. The univariate analyses indicate that patients with chronic trapezius myalgia after pain provocation due to exercise at group level showed decreased strain and unchanged strain rate while healthy controls had unchanged strain and increased strain rate. However, the multivariate analysis indicates that most patients showed lower levels according to both strain and strain rate after exercise compared to most controls.ConclusionTissue velocity imaging can help describe musculoskeletal tissue activity and dynamics in patients with chronic pain conditions. An altered muscle tissue dynamic after pain provocation/exercise among the majority of trapezius myalgia patients compared with the healthy controls was found.

Knee replacement surgery as a human clinical model of the effects of ischaemia/reperfusion upon skeletal muscle

The temporal pattern of metabolic alterations in muscle tissue during total ischaemia and reperfusion are not well-characterized in humans with respect to glutathione, amino acids and energy-rich compounds. In the present study, knee replacement surgery was used as a clinical model to elucidate this pattern of metabolic alterations. Patients (n=15) undergoing elective knee replacement surgery employing tourniquet ischaemia were studied. Muscle biopsies were taken from the quadriceps femoris muscle on the operated side preoperatively, at maximal ischaemia and after 24 h of reperfusion. The biopsies were analysed for glutathione, amino acids and energy-rich compounds. In addition the patients were randomized to receive either glucose or a mannitol infusion in the 24 h following tourniquet ischaemia. During ischaemia, muscle lactate increased by 400% (P<0.05) and phosphocreatine decreased by 70% (P<0.05). During the subsequent 24 h of reperfusion, muscle-reduced glutathione and total glutathione decreased by 27% and 22% (P<0.05) respectively. The muscle amino acid pattern changed during ischaemia with an increase in alanine by 65% (P<0.001) and a decrease in glutamate by 29% (P<0.001). During the reperfusion part of the study, no differences attributable to the infusion of mannitol or glucose were observed. During tourniquet ischaemia and subsequent reperfusion, changes in glutathione metabolism developed, indicating oxidative stress. Knee replacement surgery as a clinical model was useful during the ischaemia period, whereas the reperfusion period was dominated by the general changes seen postoperatively.

Functional exploration and quantitative histological study of muscle atrophy

SummarySome methods of electrophysiological and histological exploration that can be used for the clinical diagnosis of muscle atrophies, are described.The excitability of neuromuscular tissue may be expressed graphically by current-duration curves. These curves are different in case of partial and complete denervation.Electromyography reveals some specific modifications of electrical activity in diseased muscles, and may throw some light on the cause of an atrophy.Histopathological alterations of muscle tissue are often lacking specificity, and are of little diagnostic value, when informations about the state of innervation are not available.The pattern of muscular innervation can be studied quantitatively, by the estimation of the terminal innervation ratio and by the measurement of the variations in size and shape of the subneural apparatuses, which represent the post-synaptic part of the myoneural junction. This investigation has been performed on neuromuscular biopsies stained by original histologica...