Alterations in enzyme histochemical characteristics of the masseter muscle caused by long-term soft diet in growing rabbits.

OBJECTIVE: Recently young people have an increasing tendency to intake an easily chewable diet and spend less time on mastication. The aim of the present study was to investigate the histochemical effects of long-term soft diet on the masseter muscle in growing rabbits. MATERIALS AND METHODS: Twelve young male Japanese white rabbits were divided into two groups (n = 6 each) at weaning (1 month after birth) and fed a solid diet (control group) or a powder diet (soft-diet group). The duration of the experimental period was 6 months. Masseter fibers from the superficial and the deep portions were histochemically defined as type 1, 2A, 2B, or 2C fibers. RESULTS: As compared with that of the control, the deep masseter of the soft-diet group showed a significantly lower ratio of type 1 fiber cross-sectional area to total area (6.3 and 10.1% for the soft-diet and control group, respectively), significantly more type 2A fibers (74.0%vs 50.3%) and significantly fewer type 2B fibers (4.3%vs 12.5%). However, fiber size did not differ between the two groups. NADH-tetrazolium-reductase (NADH-TR) of the masseter was less reactive in the soft-diet group, reflecting a lower oxidative capacity. CONCLUSIONS: These findings indicate that the alteration of the functional activities contributed to selective disuse influences on the type 1 and type 2B fibers, and a resultant increase in type 2A fibers. This study suggests that long-term alteration of jaw function induced by a soft diet can lead to adaptations of the masseter muscle.

Multi-minicore disease with susceptibility to malignant hyperthermia in pregnancy.

Multi-minicore disease (MmD) is a congenital non-progressive or slowly progressive myopathy associated with multifocal degeneration of muscle fibers. Obstetric management for patients with MmD has not been described previously. A 25-year-old primigravida with a history of muscular weakness from birth was diagnosed with MmD and found to be susceptible to malignant hyperthermia (MH) by muscle biopsy at 28 weeks of gestation. Pregnancy proceeded uneventfully and she had a successful vaginal delivery under sufficient preparation for the possible occurrence of MH. Pregnant women who exhibit myopathic symptoms from childhood should consult an anesthesiologist prior to delivery.

The histochemical profiles of fibre types in porcine skeletal muscle.

Using a variety of histochemical methods -mATPase staining after alkaline and acid preincubations, NADH-TR and alpha-MGPDH- we have investigated the fibre types in porcine skeletal muscle. The results reveal that four major fibre types -I, IIA, IIB and II*- can be separated histochemically in Longissimus lumborum muscle of Landrace pigs. The histochemical properties of the muscle fibre type II* are very similar to that of type IIX described in other mammals. The existence of IIX fibres in pig muscle has been recently demonstrated by molecular biology techniques and our results validate the use of histochemistry (mATPase) as an easy methodology to differentiate the three fast myosins (type II fibres) in pig muscle.

Cardiac and skeletal muscle adaptations to voluntary wheel running in the mouse.

In this paper, we describe the effects of voluntary cage wheel exercise on mouse cardiac and skeletal muscle. Inbred male C57/Bl6 mice (age 6-8 wk; n = 12) [corrected] ran an average of 4.3 h/24 h, for an average distance of 6.8 km/24 h, and at an average speed of 26.4 m/min. A significant increase in the ratio of heart mass to body mass (mg/g) was evident after 2 wk of voluntary exercise, and cardiac atrial natriuretic factor and brain natriuretic peptide mRNA levels were significantly increased in the ventricles after 4 wk of voluntary exercise. A significant increase in the percentage of fibers expressing myosin heavy chain (MHC) IIa was observed in both the gastrocnemius and the tibialis anterior (TA) by 2 wk, and a significant decrease in the percentage of fibers expressing IIb MHC was evident in both muscles after 4 wk of voluntary exercise. The TA muscle showed a greater increase in the percentage of IIa MHC-expressing fibers than did the gastrocnemius muscle (40 and 20%, respectively, compared with 10% for nonexercised). Finally, the number of oxidative fibers as revealed by NADH-tetrazolium reductase histochemical staining was increased in the TA but not the gastrocnemius after 4 wk of voluntary exercise. All results are relative to age-matched mice housed without access to running wheels. Together these data demonstrate that voluntary exercise in mice results in cardiac and skeletal muscle adaptations consistent with endurance exercise.

Induction of a fatigue-resistant phenotype in rabbit fast muscle by small daily amounts of stimulation.

We have shown that fatigue resistance can be induced in rabbit tibialis anterior (TA) muscles without excessive power loss by continuous stimulation at low frequencies, such as 5 Hz, and that the same result is obtained by delivering a 10-Hz pattern in equal on/off periods. Here we ask whether the same phenotype could be produced with daily amounts of stimulation that would be more appropriate for clinical use. We stimulated rabbit TA muscles for 6 wk, alternating fixed 30-min on periods of stimulation at 10 Hz with off periods of different duration. All patterns transformed fast-glycolytic fibers into fast-oxidative fibers. The muscles had fatigue-resistant properties but retained a higher contractile speed and power production than muscles transformed completely to the slow-oxidative type. We conclude that in the rabbit as little as one 30-min period of stimulation in 24 h can result in a substantial increase in the resistance of the muscle to fatigue.

Autosomal dominant myopathy: missense mutation (Glu-706 --> Lys) in the myosin heavy chain IIa gene.

We here report on a human myopathy associated with a mutation in a fast myosin heavy chain (MyHC) gene, and also the genetic defect in a hereditary inclusion body myopathy. The disorder has previously been described in a family with an "autosomal dominant myopathy, with joint contractures, ophthalmoplegia, and rimmed vacuoles." Linkage analysis and radiation hybrid mapping showed that the gene locus (Human Genome Map locus name: IBM3) is situated in a 2-Mb region of chromosome 17p13, where also a cluster of MyHC genes is located. These include the genes encoding embryonic, IIa, IIx/d, IIb, perinatal, and extraocular MyHCs. Morphological analysis of muscle biopsies from patients from the family indicated to us that the type 2A fibers frequently were abnormal, whereas other fiber types appeared normal. This observation prompted us to investigate the MyHC-IIa gene, since MyHC-IIa is the major isoform in type 2A fibers. The complete genomic sequence for this gene was deduced by using an "in silico" strategy. The gene, found to consist of 38 exons, was subjected to a complete mutation scan in patients and controls. We identified a missense mutation, Glu-706 --> Lys, which is located in a highly conserved region of the motor domain, the so-called SH1 helix region. By conformational changes this region communicates activity at the nucleotide-binding site to the neck region, resulting in the lever arm swing. The mutation in this region is likely to result in a dysfunctional myosin, compatible with the disorder in the family.

[Histochemical and morphometric studies of the musculature of the forelimb of sheep with reference to its function. 2. Flexor and extensor of carpal and toe joints]. / Histochemische und morphometrische Untersuchungen der Muskulatur der Vordergliedmasse des Schafes in bezug zu ihrer Funktion Teil 2. Beuger und Strecker der Karpal- und Zehengelenke.

Muscle tissue was obtained from eight forearm muscles of six male sheep (180 days old) and stained for NADH tetrazolium oxidoreductase and myofibrillar ATPase after preincubation at pH 4.3. The fiber diameter and the percentage were determined of three fiber types: slow twitch oxidative (STO), fast twitch oxidative (FTO) and fast twitch glycolytic fibers (FTG). The extensor carpi radialis muscle had the lowest percentage of STO fibers. It is a fast extensor of the carpal joint. The superficial digital flexor muscle (FS) is located in the superficial region of the forearm has shown the highest percentage of STO fibers (50%). These fibers were also considerable larger (57 microns) than the STO fibers of the deep digital flexor muscle (39 microns). The FS supports the elbow joint extensors in the fixation of the elbow joint during the standing position (static work) and flexes the digital joints in motion (dynamic work). At first muscle function decides the quality and the quantity of the muscle fibers. Then other factors, e.g. capillarization, determine the distribution of fiber types. Muscles which have to work static-tonically require a higher content of large slow twitch fibers regardless of whether these muscles are located close to the limb axis or in the periphery. They resist lastingly gravity. Thus they are antigravity muscles. In the forearm they are the superficial digital flexor muscle, flexor carpi ulnaris muscle, and extensor carpi ulnaris muscle, which always have more than 30% STO-fibers.

[Histochemical and morphometric investigations of the musculature of forelimb mass of sheep with reference to its function. 1. Bending and extension of elbow joints]. / Histochemische und morphometrische Untersuchungen der Muskulatur der Vordergliedmasse des Schafes in bezug zu ihrer Funktion. Teil 1. Beuger und Strecker des Ellbogengelenkes.

Muscle tissue was removed from the extensors and flexors of the elbow joint of six male sheep (180 days old) and stained for NADH tetrazolium oxidoreductase and myofibrillar ATPase after preincubation at pH 4.3 in order to identify three fiber types: slow twitch oxidative (STO), fast twitch oxidative (FTO) and fast twitch glycolytic fibers (FTG). The medial head of the M. triceps brachii and the anconaeus muscle had the largest fibers (> 50 and 60 microns). The smallest muscle fibers (35-43 microns) were found in the dorsal part of the long head of the triceps muscle. The medial head of the triceps muscle and the anconaeus muscle possessed a very high percentage of STO-fibers (90 and 100%) and FTG-fibers were absent in these muscles. In the other extensors and flexors of the elbow joint the STO-percentage amounted to less than 30%. The dorsal part of the long head of the triceps muscle contained only 13% STO-fibers, but had the highest percentage of FTG-fibers (49%), which is representative of fast-muscles. The muscles of the elbow joint perform both static and dynamic functions. The medial head of the triceps brachii muscle and the anconaeus muscle possess the complement of enzymes which permits them to fulfil the work of extensors in the standing position. Therefore, they are typical of antigravity muscles. The histochemical structure of the other extensors and flexors reflect their function in motion. The lateral and long head of triceps muscle oppose the flexors and extend the elbow joint of the raised limb in the swing phase, during the landing phase they also function to support the other extensors of the elbow.

Long term effects of spinal cord transection in zebrafish: swimming performances, and metabolic properties of the neuromuscular system.

This study concerns functional recovery of zebrafish following spinal cord transection. Spinal cords were transected at the level of the 14th vertebra, just rostral to the dorsal fin. Recovery was tested at one month after transection when descending fibers start to regrow across the transection site and at three months after transection when fish perform kick and glide swimming. To estimate the rate of regrowth across the lesion site we analysed the tyrosine hydroxylase (TH) and dorsal 5-hydroxytryptamine (5-HT) systems in distal parts of lesioned cords. Both systems have cell bodies in the brainstem and in control fish TH- and dorsal 5-HT-containing fibers descend to all spinal segments. Swimming performance was studied by subjecting lesioned fish to endurance tests in a swimming tunnel with water flowing at a constant rate of 2 or 4.5 body lengths per second (BL/s). At 2 BL/s slow myotomal muscles are active whereas at 4.5 BL/s fast myotomal muscles are recruited. Control fish endured sustained swimming at both speeds for at least 3 hours. As a measure for the condition of the neuromuscular system in trunk and tail, we analysed aerobic metabolic capacities, assessed by NADH-tetrazolium reductase (NADH-TR) histochemistry of myotomal muscle fibers and spinal lateral neuropil. We found that TH- and dorsal 5-HT-immunoreactive fibers were absent in the entire distal part of lesioned cords at one month but at two months after transection they were present at approximately 6000 microns caudally to the site of the lesion. Thus the rate of outgrowth of these fibers is at least 200 microns per day. Sustained swimming at the slow speed (2 BL/s) could be endured for about 14.4 min at one month and for 23.5 min at two months after transection; there was no further improvement in the period that followed. In contrast, in the 10 weeks following transection, fast swimming (4.5 BL/s) could be endured for about 5 to 6 minutes. A significant improvement was gained in the period of 10 to 12 weeks after transection when fish could endure the high speed for almost 15 min. The aerobic capacity of muscle fibers in distal parts of the body was not strongly affected by the lesion. The only important change in aerobic capacity was observed in the neuropil of distal parts of the cords where, at three months after transection, NADH-TR activity was increased to approximately 150% of control values. On the basis of our findings, we assume that it is not the condition of the neuromuscular system, but rather a deficient co-ordination between proximal and distal body parts of lesioned fish that accounts for the relatively poor performances in endurance tests. Furthermore, differences in timing of improvements in swimming at 2 and 4.5 BL/s indicate that the spinal circuitries serving the slow parts of the neuromuscular system recover at an earlier stage than those serving the fast parts.

Mitochondrial myopathies--a clinicopathological study.

Mitochondrial myopathies are heterogeneous group of clinical disorders that can affect multiple systems besides skeletal muscles. The mitochondrial abnormalities in the skeletal muscles are morphologically identified by the presence of characteristic Ragged-red fibers (RRF) in the cryostat sections of the muscle stained with modified Gomori's trichrome stain. In this retrospective study, clinical and histopathological features in six patients with mitochondrial myopathies have been analysed. The utility of histochemical methods in confirming the diagnosis of mitochondrial myopathy has been emphasised.

A new congenital muscular dystrophy with mitochondrial structural abnormalities.

We report a new form of congenital muscular dystrophy (CMD) in 4 patients from three unrelated families with probable autosomal-recessive inheritance. All patients had the clinical characteristics of merosin-positive congenital muscular dystrophy, but had marked mental retardation. The disease was slowly progressive and 1 patient died from dilated cardiomyopathy at the age of 13 years. In addition to dystrophic changes with necrosis and regeneration in muscle, the most striking finding was mitochondrial depletion in the center of the sarcoplasm. Mitochondria at the periphery of fibers were markedly enlarged ("megaconial" appearance) with complicated cristae, and contained a normal amount of mitochondrial DNA by in situ hybridization. Mitochondrial enlargement may represent functional compensation for mitochondrial depletion in the central sarcoplasm, where myofibrillar degeneration occurred.

The interstitial gland of ovary of ewes from birth to sexual maturity.

The morphological and functional development of the interstitial gland was studied in crossbred ewe lambs (East Friesian x Black-Head Pleven breeds) first birth and then at 1, 2, 3, 4, 5, 5.5 and 6 months, as well as at 1 year in anestrous ewes. Histological and histochemical (AP, NAD.H2-tetrasole reductase, G-6-PDH and delta(5)-3 beta-hydroxysteroid dehydrogenase (delta(5)-3 beta-HSD)) methods and transmission electron microscopy (TEM) were applied while the FSH and LH levels were measured. There was an abundance of epithelial cell cords in newborn animals, while interstitial cells were scanty. Cortical and medullary epithelial cell cords occupied an essential place in the histogenesis of ovine ovarian structures. They were clearly expressed during the whole postnatal period of the development, and showed a species specificity. The development of the interstitial gland was correlated with changes in the gonadotropic hormones. A new population of interstitial glands appeared around puberty in a similar manner to the so-called 'puberty gland' in the testis and ovary of humans and other mammals. The results suggest that in these crossbred lambs, puberty was attained between the 3rd and 4th month, and sexual maturity and 5 to 6 months of age.

Differences in distribution of myofiber types between the supraspinatus and infraspinatus muscles of sheep.

BACKGROUND: The m. supraspinatus stabilizes the shoulder joint to bear the body weight, and the m. infraspinatus assists in extension and flexion of the joint in sheep. Postural muscles have many SO myofibers, whereas locomotory muscles have numerous fast-twitch myofibers. In sheep the distribution of myofiber types within the two muscles, necessary for a better understanding of postural function, remains to be clarified. METHODS: Muscle samples were removed from the whole transverse sections of the dorsal, middle, and ventral compartments of the m. supraspinatus and m. infraspinatus of sheep. Myofibers were classified into FG, FOG, SO-1, and SO-2 myofibers by histochemical methods. RESULTS: The distribution of SO myofibers changed more greatly in the m. supraspinatus (15.0-99.1%) than in the m. infraspinatus (24.5-62.3%). SO myofibers were concentrated markedly in the caudal and deep regions near the spine and fossa of the scapula in the m. supraspinatus and distributed more in the medial part than in the lateral part in the m. infraspinatus. Such changes were caused by increases in percentage of SO-2 myofibers and not SO-1 myofibers. The craniolateral regions of the m. supraspinatus and the caudolateral regions of the m. infraspinatus had many fast-twitch (FOG plus FG) myofibers suited for rapid extension and flexion of the shoulder joint. CONCLUSIONS: The m. supraspinatus has the compartmentalized, deep, and caudal regions occupied by SO myofibers, which seem to be specialized for maintenance of the joint extension. The medial region of the m. infraspinatus may assist in the joint stabilization.

Respiratory chain enzyme defects in patients with idiopathic inflammatory myopathy.

OBJECTIVE: To analyse muscle respiratory chain enzymes in idiopathic inflammatory myopathy. METHODS: Four consecutive female patients seen at our hospital with idiopathic inflammatory myopathy were studied. Muscle histochemical staining included NADH tetrazolium reductase and succinate dehydrogenase tests. Activity of rotenone sensitive NADH cytochrome c reductase (complex I and III) succinate dehydrogenase (complex II), succinate cytochrome c reductase (complex II and III), cytochrome c oxidase (complex IV), and citrate synthase (a mitochondrial matrix enzyme), was measured spectrophotometrically in muscle homogenates. Free carnitine, and short and long chain acylcarnitine esters were determined in muscle homogenates by a radiochemical procedure. RESULTS: Three patients had mitochondrial proliferation in nonregenerating muscle fibres; these patients had defects of respiratory chain enzyme complexes. Carnitine concentrations, measured in two of the four patients, revealed carnitine deficiency in one. CONCLUSION: Our results suggest that mitochondrial dysfunction may be present in patients with inflammatory myositis.

Enzyme-histochemical profiles of fiber types in mature canine appendicular muscles.

The histochemical characteristics of skeletal muscle were assessed using a range of samples from 7 appendicular muscles taken from adult mixed-breed dogs (1.5 to 3 years of age). Two slow-twitch fiber subtypes (IA and IB) and three II subtypes (IIA, IIB and IIC) were identified according to myofibrillar myosin adenosine triphosphatase reaction after acid and alkaline preincubation. Type IIB fibers were not found in all muscles, and were only biologically significant in m. semitendinosus. The metabolic potential of these fibers is fairly similar to that of IIA fibers, but significantly different to that of IIB fibers in other mammals, suggesting that they may be designed to play a different functional role during locomotion. All canine muscle fibers have moderate to high oxidative capacity, which may be related to the extraordinary athletic capability of the species.

Skeletal muscle characteristics in red blood cell normovolaemic and hypervolaemic standardbred racehorses.

Muscle biopsy specimens from the middle gluteal muscle were studied in 16 red blood cell hypervolaemic (Group HV) and 19 normovolaemic (Group NV) Standardbred racehorses. All horses were stallions, 4-8 years old and having similar mean racing performance values, as described by an individual selection index value. All horses raced regularly but those in Group HV did not perform as expected and were therefore referred to the clinics for exercise tolerance testing. Muscle biopsy specimens were analysed for fibre type distribution (Type I, IIA and IIB), fibre area and relative fibre area. In addition, oxidative capacity of the fibres was evaluated by staining for nicotinamide adenine dinucleotide (NADH) tetrazolium reductase, and the activities of citrate synthase, 3-OH-acyl CoA dehydrogenase and lactate dehydrogenase were analysed in whole-muscle samples. With the exception of a higher percentage of Type IIB fibres in Group HV having a high oxidative capacity as evaluated by the NADH stain, no significant difference were found in fibre composition, fibre area or enzyme activity between the Groups HV and NV.

Calcitonin gene-related peptide expression at endplates of different fibre types in muscles in rat hind limbs.

Calcitonin gene-related peptide (CGRP) occurs only in some motoneurons. In this study, the presence of CGRP in motor endplates in relation to muscle fibre types was examined in slow (soleus muscle) and fast [tibialis anterior (TA) and extensor digitorum longus (EDL)] leg muscles of the rat. CGRP was detected by use of immunohistochemical methods, and staining for the mitochondrial-bound enzyme NADH-TR was used for demonstration of fibre types. The fibres showing low NADH-TR activity were interpreted as representing IIB fibres. All such fibres located in the superficial portion of TA were innervated by endplates displaying CGRP-like immunoreactivity (LI), whereas in the deep portion of TA some of these fibres lacked CGRP-LI at their endplates. Thirty per cent of the IIB fibres in EDL showed CGRP-LI at the endplates. All fibres in TA and EDL displaying high NADH-TR activity and interpreted as type-IIA fibres, lacked CGRP-LI in their motor innervation. One third of the fibres with intermediate NADH-TR activity in TA exhibited CGRP-LI at their endplates, whereas in EDL only few such fibres displayed CGRP-LI in the endplate formation. These fibres are likely to belong to type-IIX or type-I motor units. CGRP-LI was very rarely detected at the endplates in the soleus muscle. These observations show that distinct differences exist between the slow muscle, soleus, and the fast muscles, TA and EDL, but that there are also differences between the different types of fibres in TA and EDL with respect to presence of CGRP-LI at the endplates.(ABSTRACT TRUNCATED AT 250 WORDS)

[Histochemical and ultrastructural study of myotonic dystrophy].

The pathological, histochemical and ultrastructural changes in the muscular biopsies from 9 patients with myotonic dystrophy were investigated. The major changes observed under light microscopy were degeneration of muscle fibers, increased number of nuclei, tendency of central nuclei to form chains, subsarcolemmal masses of cytoplasm and circularly arranged fibrils. The myosin ATPase and NADH-TR stain demonstrated histochemical selectivity of type I fiber atrophy in 7 of the 9 cases studied. The outstanding ultrastructural changes were extensive small disruptions of plasma membrane, destructions of Z bands and myofilaments, swelling of mitochondria, dilatational sarcoplasmic reticulum and regeneration of muscle fibers. Genetic fault of the surface membrane is a possible cause that leads to enzyme metabolic disorder, mitochondrial calcium overload, increased calcium content in sarcoplasm, resulting finally in mitochondrial metabolic disorder, myofilament destruction and muscle fiber necrosis.

Histochemical and morphometric properties of muscles of the upper airway of goats.

This study investigated the histochemical and morphometric properties of fibres in laryngeal, hyoid, tongue and pharyngeal muscles which contribute in maintaining patency of the upper airway. Muscle specimens from adult female goats were stained for nicotinamide adenine dinucleotide dehydrogenase-tetrazolium reductase and myosin adenosine triphosphatase activities, and the composition and size of the fibre types determined. These muscles contained types 1, 2A, 2B and 2C fibres with type 2 fibres predominating and the fibres possessed oxidative enzyme activity suggesting fast contraction speed and yet moderate resistance to fatigue. Abductor laryngeal muscles contained more type 1 fibres than the adductors. Among pharyngeal muscles fibre size and type 1 fibre composition increased progressively from the hyopharyngeus caudally. Upper airway muscles contained relatively small fibres (range of mean diameter: 25.7 to 46.1 microns) with the pharyngeal and lingualis proprius muscles containing the smallest fibres. These properties might influence the response of upper airway muscles to neuromuscular blocking drugs.