Studies of human antagonistic muscles after rupture of the tendon of biceps brachii

The fibre type ratio and the cross sectional areas of fibres were studied in triceps brachial muscle after rupture of tendon of the biceps brachial muscle in man. On the healthy and injured sides of the m. triceps brachii, the mean value of type 1 fibres was 51.9% and 52.4%, respectively. The mean cross sectional area of fibre on the two sides of the triceps muscle varied considerably among individuals without any significant correlation to injury of the biceps tendon.     

Lipoprotein lipase activity in skeletal muscles of the rat: effects of denervation and tenotomy.

The effects of denervation, tenotomy, or tenotomy with simultaneous denervation on the activity of heparin-releasable and intracellular, residual lipoprotein lipase (LPL) and triacylglycerol (TG) content were examined in rat skeletal muscles. An influence of muscle electrostimulation on denervated and tenotomized muscles was also evaluated. Activity of both LPL fractions was decreased in denervated and/or tenotomized soleus and red portion of gastrocnemius muscles. It was accompanied by a slight elevation of the intracellular TG content. Electrostimulation increased activities of both fractions of LPL in red muscles from intact hindlimbs. In stimulated denervated muscles without or with simultaneous tenotomy, activity of two LPL fractions was also enhanced, but control values were reached only in denervated soleus muscle. Electrical stimulation had no pronounced effect on LPL activity in tenotomized muscles. In conclusion, denervation and/or tenotomy decreases LPL activity in red muscles, indicating reduction of the muscle potential to utilize circulating TG. Electrostimulation only partly restores the diminished LPL activity in denervated muscles, without any effect in tenotomized ones. Thus, to maintain LPL activity in resting muscle, intact innervation and tension are needed.     

Mucosubstances in the human skeletal muscles.

With histomchemical, and electronmicroscopic-histochemical methods two types of human skeletal muscle fibres were established. The first type of muscle fibres does not contain acidic mucosubstances. The staining reactions and cellulase digestion indicate that, the neutral polysaccharides are cellulose-like substances. The second type of fibres contains only acidic mucosubstances, hyaluronic acid and chondroitine sulphate. The author suggests that the mucosubstances have joint function. These polysaccharides contributed to the jointing both of myofibrils and sarcomers. The polysaccharides can be exhibited in the joint points of contractile elements. In mechanical injury this point became disintegrated.     

Proximal skeletal muscle alterations in streptozotocin-diabetic rats: a histochemical and morphometric analysis.

The response of rat quadriceps muscle fibers to chronic streptozotocin (STZ) diabetes was studied. Transverse sections of rectus femoris muscle from diabetic and weight-matched control rats were assayed for myofibrilar adenosine triphosphatase (ATPase) and nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR). A quantitative analysis was carried out by an automatic interactive analysis system focused on the fiber type size and distribution. STZ-induced diabetes caused important effects in this muscle, with changes in the distribution of oxidative enzyme reactions, type I fiber hypertrophy, and type II fiber atrophy, which was greater in type IIB than in type IIA. It is concluded that hypoinsulinism produces morphological alterations in proximal skeletal muscle fibers that are similar to those of neurogenic myopathy. Thus the pathological changes in these mammalian muscle fibers could explain the clinical syndrome seen in diabetic patients called "diabetic symmetrical proximal motor neuropathy," perhaps the least understood of the major neuropathic complications of diabetes.     

Ultrastructural alterations in cardiac and skeletal muscles in experimental diabetes mellitus

In 18 alloxan-diabetic and 12 metabolically healthy dogs cardiac and skeletal muscles have been studied electronmicroscopically. Myopathy-like alterations, as widening of Z band material, alterations of mitochondria as well as of collagen fibers were observed in the diabetic myocardium. In skeletal muscle nemalin bodies were found. These latter alterations don't develop in insulin-treated diabetic state.     

Aging of human skeletal muscles

Normal aging in humans is associated with progressive decrease in skeletal muscle mass and strength (sarcopenia) which contributes to frailty and falls. The age associated changes in body composition result from lower levels of anabolic hormones, oxidative damage, neuromuscular alterations and a general decrease in muscle protein turnover. In this review we discuss the potential mechanisms and physical activity as prevention and treatment of sarcopenia.     

The value of enzyme histochemical techniques in classifying fibre types of human skeletal muscle. 1. Adult skeletal muscles with no apparent disease of the neuromuscular system.

Fibre-type classification of human skeletal muscle into type I and type II fibres is mostly based on their slight or strong staining with the myosin adenosine triphosphatase reaction. In order to evaluate the reliability of this screening technique a combined histochemical and biochemical study was performed on normal and diseased skeletal muscle of human subjects. In the present investigation activities of enzymes which play a role in the aerobic and anaerobic pathways and which can characterize fibre type, were examined in muscle specimens, with no apparent disease of the neuromuscular system. Special attention is given to the maximal activities of phosphofructokinase and fructose-1,6-diphosphatase, the rate limiting enzymes for the regulation of the glycolysis and glyconeogenesis, respectively. A most important feature of the biochemical findings is the constancy of the activity ratios of the examined enzymes. From these results and from the histochemical results it can be concluded that in apparently normal adult human skeletal muscle the ATP-ase technique for type I and type II typing is reliable. For fibres with an intermediate intensity of staining with the myosin ATPase technique of typing it is also necessary to apply other enzyme histochemical techniques.     

A predictive model of fatigue in human skeletal muscles.

Fatigue is a major limitation to the clinical application of functional electrical stimulation. The activation pattern used during electrical stimulation affects force and fatigue. Identifying the activation pattern that produces the greatest force and least fatigue for each patient is, therefore, of great importance. Mathematical models that predict muscle forces and fatigue produced by a wide range of stimulation patterns would facilitate the search for optimal patterns. Previously, we developed a mathematical isometric force model that successfully identified the stimulation patterns that produced the greatest forces from healthy subjects under nonfatigue and fatigue conditions. The present study introduces a four-parameter fatigue model, coupled with the force model that predicts the fatigue induced by different stimulation patterns on different days during isometric contractions. This fatigue model accounted for 90% of the variability in forces produced by different fatigue tests. The predicted forces at the end of fatigue testing differed from those observed by only 9%. This model demonstrates the potential for predicting muscle fatigue in response to a wide range of stimulation patterns.     

Protein synthesis in adult skeletal muscle after tenotomy: responses to fasting and insulin infusion.

Muscle growth was established in specific muscles in the hindlimb of adult female rats by tenotomy of the gastrocnemius muscle. Seven days after surgery there was an increase in the wet weight of the soleus (Sol) and plantaris (P) muscles and a decrease in that of the gastrocnemius (G) muscle from the tenotomized limb compared with the respective control muscles from the contralateral limb from the same animal. In all three muscles there was a significant increase in the fractional rate of protein synthesis (ks) in the muscles from the tenotomized limb above the rate of the respective control muscles. In contrast, the extensor digitorum longus (EDL) muscle showed no change in wet weight or ks 7 days after tenotomy of G. Fasting for 12 or 36 h had no significant effect on ks in G, P, or Sol muscles from either the control or tenotomized limbs. In EDL from the control limb, both fasting periods resulted in a significant decrease in ks, although this effect was not seen in the EDL from the tenotomized limbs of the same animals. A subsequent 30-min insulin infusion was similarly ineffectual in G, P, and Sol, with its only effect evident in the EDL from the control limb, where it was sufficient to reverse the decreased ks resulting from the fasting, even though after 36 h fasting the reversal was only partial.     

Histochemical profiles of guinea-pig intrafusal fibres in normal muscles and after denervation, cordotomy and tenotomy

Synopsis Histochemical profiles of intrafusal fibres were analysed in normal muscles and in denervated, cordotomized and tenotomized preparations. Based on ATPase activity at polar regions, normal intrafusal fibres were classified as (I) ATPase-light fibres showing low or low-moderate activity when pre-incubated in either an acid or alkaline medium; (2) ATPase-dark fibres demonstrating high activity when preincubated in either an acid or alkaline medium and (3) ATPase-reversing fibres displaying low to moderate activity when pre-incubated in an acid medium, but showing high activity when pre-incubated in an alkaline medium. Four weeks after nerve section contrasting responses were seen between intrafusal fibre types. The ATPase-reversing fibres showed large decreases in polar cross-sectional area and NADH-diaphorase (NADH-D) activity, whereas fibres of the ATPase-light and ATPase-dark types were less subject to atrophy and their NADH-D levels were frequently increased. This differential effect suggests that ATPase-reversing fibres are trophically more dependent on neural innervation than ATPase-light and ATPase-dark fibres. After cordotomy and tenotomy no such marked differential responses were noted between fibre types.     

Local NO synthase inhibition produces histological and functional recovery in Achilles tendon of rats after tenotomy

Repair of injured tendon is a very slow process and involves the release of many molecules, including nitric oxide. We investigate the influence of local nitrergic inhibition in histological and functional recovery of injured Achilles tendon. A standard murine model of tendon injury by rupture was used. The animals were divided into three experimental groups: control, injury + vehicle (normal saline) and injury + Nω-nitro-L-arginine methyl ester (L-NAME). The products were injected into the paratendinous region every 2 days and body weight gain and Achilles functional index (AFI) were evaluated on days 0, 7, 14 and 21 after tendon injury. On day 21 post-injury, the animals were killed to evaluate nitric oxide production and tissue organization. We observed that tendon surgical division led to increased tissue nitrite levels, which were reduced in L-NAME-treated rats. The AFI revealed functional recovery of L-NAME-treated animals on day 21 post-injury, which was not observed in the saline-treated group. Microscopic analysis of hematoxylin-eosin staining and collagen autofluorescence showed that L-NAME-treated rats had more aligned areas of collagen fibers and that the diameter of newly organized collagen in this group was also greater than that in the vehicle-treated one. We demonstrate that local treatment with L-NAME significantly improves the functional parameters and accelerates histomorphological recovery.     

Enzyme histochemical studies on the pathological changes in human Sertoli cells

Two forms of human Sertoli cell disorders were characterized enzyme histochemically from the testicular biopsy material of infertile and subfertile patients. Sertoli cell asthenia: a slight injury of the Sertoli cell with exfoliation of individual germ cells; marked by the rarefaction of reaction zones of thiamine pyrophosphatase (TPPase) and a decrease in lactate dehydrogenase (LDH). Sertoli cell insufficiency: severe Sertoli cell damage with the formation of a "puff" and a heavy exfoliation of germ cells (dislocation of Sertoli cell nucleus and cytoplasm along with the related germ cells into the lumen of seminiferous tubule); marked by a heterogeneous activity pattern of TPPase, the disappearance of LDH, maintenance of a slightly weakened activity of alkaline phosphatase, and an increase of acid phosphatase. In the case of Sertoli-cell-only syndrome, the high prismatic Sertoli cells showed strong acid phosphatase activity with scattered weak TPPase reaction, whereas the flat or cube-like Sertoli cells exhibited weak acid phosphatase activity with only one small round reaction zone of TPPase in each cell. In addition, the frequency of the occurrence of Sertoli cell asthenia, Sertoli cell insufficiency, and Sertoli-cell-only syndrome is reported, and its correlation with the andrological diseases discussed.