Morphological classification and comparison of suboccipital muscle fiber characteristics / 대한해부학회지

In an attempt to clarify the function of the suboccipital muscles, we performed morphological observation of the suboccipital muscles for variations in the muscle belly and compared the morphology of their muscle fibers in terms of cross-sectional area by immunostaining with anti-myosin heavy chain antibodies. The cadavers of 25 Japanese individuals were used: 22 for morphological examinations and three for histological examinations. Among samples of the rectus capitis posterior major muscle (RCPma) and rectus capitis posterior minor muscle (RCPmi), 86.4% had a typical muscle appearance with a single belly, and 13.6% had an anomalous morphology. None of the samples of the obliquus capitis superior (OCS) or obliquus capitis inferior (OCI) muscles had an anomalous appearance. Measurement of cross-sectional area revealed that fast-twitch muscle fibers in the RCPma and OCI had a significantly greater cross-sectional area than those of the RCPmi and OCS. The cross-sectional area of intermediate muscle fibers was also significantly greater in the OCS than in the RCPma, RCPmi, and OCI. The cross-sectional area of slow-twitch muscle fibers was significantly greater in the OCS than in the RCPma, RCPmi, and OCI, and the RCPmi showed a significantly greater cross-sectional area for slow-twitch muscle fibers than did the RCPma, and OCI. Our findings indicate that the RCPmi and OCS exert a greater force than the RCPma and OCI, and act as anti-gravity agonist muscles of the head. Prolonged head extension in individuals with anomalous suboccipital muscle groups could result in dysfunction due to undue stress.

Histochemistry profile of the biceps brachii muscle fibres of capuchin monkeys (Cebus apella, Linnaeus, 1758) / Perfil histoquímico das fibras do músculo bíceps braquial do macaco-prego (Cebus apella, Linnaeus, 1758)

A general analysis of the behaviour of “Cebus” shows that when this primate moves position to feed or perform another activity, it presents different ways of locomotion. This information shows that the brachial biceps muscle of this animal is frequently used in their locomotion activities, but it should also be remembered that this muscle is also used for other development activities like hiding, searching for objects, searching out in the woods, and digging in the soil. Considering the above, it was decided to research the histoenzimologic characteristics of the brachial biceps muscle to observe whether it is better adpted to postural or phasic function. To that end, samples were taken from the superficial and deep regions, the inserts proximal (medial and lateral) and distal brachial biceps six capuchin monkeys male and adult, which were subjected to the reactions of m-ATPase, NADH-Tr. Based on the results of these reactions fibres were classified as in Fast Twitch Glycolitic (FG), Fast Twitch Oxidative Glycolitic (FOG) and Slow Twitc (SO). In general, the results, considering the muscle as a whole, show a trend of frequency FOG> FG> SO. The data on the frequency were studied on three superficial regions FOG=FG>SO; the deep regions of the inserts proximal FOG=FG=SO and inserting the distal FOG>FG=SO. In conclusion, the biceps brachii of the capuchin monkey is well adapted for both postural and phasic activities.

Uma análise geral do comportamento do “Cebus apella” mostra que este primata quando desloca para se alimentar ou realizar outra atividade apresenta diferentes maneiras de locomoção. Estas informações mostram que o músculo bíceps braquial deste animal é usado freqüentemente nas suas atividades de locomoção, mas deve ser lembrado ainda que este músculo é usado também para desenvolvimento de outras atividades como esconder-se, procurar objetos, vasculhar arboredos, além de cavar o chão. Considerando-se o exposto acima decidiu-se pesquisar as características histoenzimológicas do músculo bíceps braquial do macaco-prego com o objetivo de comparar se este músculo esta melhor adaptado para funções posturais ou fásicas. As amostras foram retiradas das regiões superficiais e profundas; inserções proximais (medial e lateral) e distal de seis macacos-prego machos e adultos, os quais foram submetidos às reações de m-ATPase, NADH-Tr. Baseado nos resultados das reações, as fibras foram classificadas em Fast Twitch Glycolitic (FG), Fast Twitch Oxidative Glycolitic (FOG) e Slow Twitch (SO). Quanto à área dos diferentes tipos de fibras, os resultados encontrados foram semelhantes em todas as amostras estudadas, e as fibras de contração rápida foram sempre maiores do que as de contração lenta (FG=FOG>SO). Os dados obtidos sobre a frequência foram: nas três regiões superficiais estudadas FOG=FG>SO; nas regiões profundas das inserções proximais FOG=FG=SO e na inserção distal FOG>FG=SO. Baseado nestes dados pode-se concluir que o músculo bíceps braquial do macaco-prego está bem adaptado tanto para atividades posturais como fásicas.

[ effect of resistance training on plasma and skeletal muscles sphingosine-1-phosphate levels of male Wistar rat]

Sphingosine 1-phosphate [S1P] is a bioactive platelet-derived sphingolipid that is involved in regulation of proliferation, differentiation, hypertrophy and anti-apoptosis of cells and activation of satellite cells. The purpose of present study was to examine the effect of resistance training on S1P levels of plasma and skeletal muscles in male Wistar rats. Twenty four 8-week-old male Wistar rats were used in this study. The initial body weight of rats was 190 to 250 gr. All animals were maintained in pairs in an environmentally controlled room at 22°C, 12:12-h photoperiod cycle and allowed normal cage activity. The animals were fed standard rat chow and water ad libitum. After a week of acclimation to the animal facility, the rats were assigned randomly to a control [N=12] or training [N=12] group. Resistance training was done using a 1 meter height ladder with 2 cm grid with an 85 degree incline, and weights attached to rat's tails. The content of sphingosine-1- phosphate [S1P] present in the chloroform layer was determined by means of high performance liquid chromatography [HPLC]. Resistance exercise training increased the total content of S1P in FHL [fast-twitch] [P=0.003] and soleus [slow-twitch] [P=0.008] muscles and plasma [P=0.001] in comparison with control group. It is concluded that resistance exercise training strongly affects the S1P content in fast and slow twitch muscles and plasma

The relationship between contractile characteristics and fiber type conversion in hind-limb unloading mice soleus / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore the relationship between contractile characteristics and fiber type conversion in hind-limb unloading mice soleus.</p><p><b>METHODS</b>After 28-day hind-limb unloading and muscle atrophy, we used the method of isolated muscle perfusion with different stimulated protocols to determine the changes in contractile characteristics including the isometric twitch force and tetanus force and fatigue index of slow twitch muscle in mice. The muscle myofibrillar composition and fiber type conversion were detected by immunofluorescence staining and real-time PCR.</p><p><b>RESULTS</b>The isometric twitch force and the tetanus force and fatigue index were decreased progressively in 28-day unloaded mice soleus, with the increase in fast twitch fiber subtype and the decrease in slow twitch fiber subtype.</p><p><b>CONCLUSION</b>The alteration of contractile characteristics is relevant to the slow-to-fast fiber conversion in mice soleus after 28-day hind-limb unloading.</p>

Type IIB human skeletal muscle fibers positively correlate with bone mineral density irrespective to age / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Age-associated decrease in type IIA/B human skeletal muscle fibers was detected in human biopsies in our previous study. The relationship between change in muscle fiber typing and bone mineral density (BMD) is, however, unknown either cross-sectionally or longitudinally. We therefore conducted a cross-sectional study to investigate their correlation using human muscle biopsies.</p><p><b>METHODS</b>Forty human subjects aged (53.4 ± 20.2) years were recruited. Histomorphometric parameters of their muscle biopsies were measured by ATPase staining and image analysis, including average area percentage, fiber number percentage, mean fiber area, and area percentage of connective tissues. Hip and spine BMD was measured by dual-energy X-ray absorptiometry. Partial correlation with adjusting age was performed.</p><p><b>RESULTS</b>Type IIB muscle fiber was found positively correlated with hip BMD irrespective to age and demonstrated significantly stronger relationship with BMD among all fiber types, in terms of its cross-sectional area (r = 0.380, P = 0.029) and size (r = 0.389, P = 0.025). Type IIA muscle fibers associated with hip BMD in mean fiber area only (r = 0.420, P = 0.015).</p><p><b>CONCLUSIONS</b>Type IIB muscle fiber may play an important role in maintaining bone quality. This may also be a relatively more sensitive fiber type of sarcopenia and osteoporosis. These findings further consolidate the muscle-bone relationship.</p>

[Effects of endurance and resistance training on calcitonin gene-related content in slow and fast twitch rat muscles]

Calcitonin Gene-Related Peptide [CGRP], a 37-amino acid peptide generated by alternative processing of primary transcripts from calcitonin gene, is broadly distributed in the peripheral and central nervous systems of vertebrate and invertebrate species, CGRP plays a main role in the neuromuscular junction. This paper investigates the effects of endurance and resistance training on the content of CGRP in the slow and fast twitch muscles. Twenty-two male Wistar rats, [age 10 mo, weight 220 +/- 20gr, Pasteur Institute] were randomly divided to three groups.] Control [n=7], Endurance training [n=7], and Resistance training [n=8]] and underwent 12 weeks training according to protocols. Animals of the resistance training group were housed in a metal cage with a wire-mesh tower; endurance training included treadmill running], 5 days a week, 60 min/day, 30 m/min speed, for animals in this group. Forty-eight hours after last session of protocols, animals were anaesthetized. The right soleus and anterior tibialis were removed, and, tissues were immediately frozen in liquid nitrogen and kept at -70°C for use later. CGRP content was measured by the ELISA method. For data analyses, one-way ANOVA was used. There was no significant difference between control and endurance training groups in the CGRP of slow and fast twitch muscles. However the content of CGRP in both fast and slow twitch muscles was significantly different in the resistance training group as compared to the control group. That training can be a main factor for CGRP release in muscles. In addition, the type and intensity of activity probably contribute to increase in CGRP content

Effects of Ischemic Preconditioning on the Phosphorylation of Akt and the Expression of SOD-1 in the Ischemic-reperfused Rat Skeletal Muscles / 체질인류학회지

Akt, a key protein of cell survival, can promote cell growth and survival by activations of various cellular protective factors. Ischemic preconditioning (IP) has been known to reduce ischemic injury through upregulation of phosphorylation of Akt (p-Akt). CuZn-superoxide dismutase (SOD-1), an antioxidant enzyme, scavenges reactive oxygen species and protects cell from oxidative stress by increasing the activaiton of Akt. The present study was performed to examine the effects of IP on the expression of p-Akt and SOD-1 in the ischemicreperfused rat skeletal muscles. Thirty weeks old male SD rats were divided into 4 groups, such as controls, IP, 4 hour ischemia and 4 hour ischemia with IP. For IP, commom iliac artery was occluded three times for 5 min ischemia followed by 5 min reperfusion using rodent vascular clamps. Ischemia was induced by occlusion on the same artery for 4 hours. The Tibialis anterior and Soleus were removed at 0, 1, 3, and 24 hours of reperfusion. The expressions of p-Akt (Ser 473) and SOD-1 were examined with immunohistochemistry and Western blot analysis.In the IP group, the p-Akt and SOD-1 were increased, compared to the control group. In the ischemia group, the p- Akt and SOD-1 were decreased, compared to the control group, and were more abundant when reperfusion time were increased. IP increased the p-Akt and SOD-1 after 4 hour ischemia, and the p-Akt and SOD-1 were higher in Soleus compared to Tibialis anterior. These findings suggest that IP increases p-Akt and expression of SOD-1 in the ischemic-reperfused rat skeletal muscles, and that upregulations of p-Akt and SOD-1 induced by IP were higher in the red muscle fiber, Soleus, than the white muscle fiber, Tibialis anterior.

Morfologia e morfometria dos tipos de fibras do músculo reto abdominal de cadelas (Canis familiaris) durante a gestação / Morphologic and morphometry of rectus abdominis muscle fiber types of the during the gestation dog (Canis familioris)

Neste trabalho foram avaliadas as alterações morfológicas e o grau de hipertrofia das fibras de contração lentas (tipo I) e rápidas (tipo II) do músculo reto abdominal de cadelas adultas nas fases: pré-gestacional, 30 e 60 dias de gestação e 30 dias pós-parto (pp). Em todas essas fases, sob anestesia, foram removidas biópsias musculares, as quais foram congeladas. Cortes histológicos foram obtidos em um micrótomo e corados com hematoxilina e eosina (HE) para a avaliação da morfologia. Outros cortes foram submetidos à ATPase miofibrilar (m-ATPase), após pré-incubação em meio alcalino (pH = 10,4) e em meio ácido (pH = 4,4), visando à identificação das fibras tipo I e II. Nas cadelas virgens, o tecido muscular revelou-se constituído por fibras com diferentes diâmetros, com contornos poligonais, tendo um ou mais núcleos periféricos. Estas características foram similares nos animais com 30 dias de gestação. Aos 60 dias, ao lado de fibras com aparência normal, observaram-se fibras com contornos mais polimórficos e outras fibras de diâmetros muito pequenos. Aos 30 dias pp, as características do tecido foram similares às dos animais em fase pré-gestacional. Em todas as fases estudadas, os diâmetros fibras tipo II foram maiores do que as do tipo I. Aos 30 dias observou-se a redução significativa dos diâmetros de ambos os tipos de fibras e aumento significativo aos 60 dias de gestação. Durante a gestação, o estímulo crônico, representado pela expansão da parede abdominal, promoveu alterações da morfologia e morfometria das fibras.

The present paper deals with the evaluation of morphological and morphometric alterations of slow-twist (I) and fast-twitch (II) fibers of rectus abdominis muscle of adult female dog during pre-gestational phase, at 30 and 60 days of pregnancy and at 30 days after the porturition. At the every phases, using the open biopsy technique, muscle samples were collected. The samples were plunged. Histological sections were cut in a microtome. For general morphology, some sections were stained with HE. Subsequent sections were reacted for myofibrillor ATPase (m-ATPase), after alkaline (pH 10.4) and acid (pH 4.4) pre-incubations, in order to identificate type I and II fibers. In the pre-gestational phase, muscle tissue revealed to be composed by fibers with different diameters, presenting polygonal outlines and one or more periphery nuclei. At 30 days of pregnancy, muscle fiber characteristics were similar. At 60 days, in addition to the existence of normal fibers, polymorphic and small diameter fibers were frequent. At 30 days after the parturation, the morphology of muscle fiber were similar to that observed in the pre-gestational phase. In the four phases, type II fiber diameters were lager than type I. The diameters of both fiber types showed a significant reduction in the 30 days phase and a significative increasing at 60 days. The expansion of the abdominal wall during the pregnancy represents a chronic stimulus, induced changes in the morphology and in the fiber type diameters.

Metabolic and physiologic characteristics of skeletal muscle determine its response to clenbuterol treatment.

beta-Adrenoceptor agonists are reported to induce skeletal muscle hypertrophy and hence serve as valuable adjunct to the treatment of wasting disorders. In the present study, we attempted to find out whether metabolic and physiologic characteristics of fibres are important in determining skeletal muscle response to clenbuterol (an adrenergic receptor agonist) therapy, as proposed in the treatment of wasting disorders. The treatment of mice with clenbuterol (2 mg/kg body wt for 30 days) resulted in skeletal muscle hypertrophy, more common amongst fast-twitch glycolytic fibres/muscle, with increase in body mass and a parallel rise in muscle mass to body mass ratio. Measurement of fibre diameters in soleus (rich in slow-twitch oxidative fibres), ALD or anterior latissimus dorsi (with a predominance of fast-twitch glycolytic fibres) and gastrocnemius (a mixed-type of muscle) from clenbuterol-treated mice for 30 days revealed noticeable increase in the per cent population of narrow slow-twitch fibre and a corresponding decline in white-type or fast-twitch glycolytic fibres in gastrocnemius and ALD. As revealed by counting of muscle cells in soleus, narrow red fibres declined with corresponding increase in white-type glycolytic fibres population. A significant decline in the succinic dehydrogenase activity was observed, thereby suggesting abnormality in oxidative activity of skeletal muscles in response to clenbuterol therapy.

Effect of testosterone on skeletal muscle of young and old male rats

The effects of testosterone on skeletal muscle were assessed in adult male Wistar rats aged 80 days and 1 year. The animals were divided into 4 groups: young testosterone (YT), old testosterone (OT), young control (YC), and old control (OC) groups. The YT and OT groups received 15 applications of testosterone cypionate (5 mg/kg) on alternate days and the controls received injections containing sterile oil alone. After 30 days the animals were sacrificed and the soleus (SOL) and extensor digitorum longus (EDL) muscles were analyzed using mATPase histochemistry. After treatment, YT group gained less body weight than YC group and OT group decreased body weight, differently from the body weight gain observed in the OC group. Testosterone treatment did not show significant changes in both relative muscle weight and muscle fiber composition profile. However, in the YT group we observed an increase in the cross-sectional area of type I fibers in the SOL muscle, and type I and IIAD fibers in the EDL muscle. In the OT group, the cross sectional area of type I was decreased in the EDL muscle. These results reveal that testosterone did not cause a shift in muscle fiber type, but the cross-sectional area had fiber type-specific changes.

Some bio-medical mechanisms in athletic prowess / Algunos de los mecanismos biomédicos de las proezas atléticas

Variations in somato-genetic patterns in muscle-fibre biology, biochemical metabolic pathways and pulmonary physiology are hypothesized to have been concentrated by natural selection over the centuries in the Afrocentric peoples displaced from West Africa to the New World. These phenotypic and genotypic characteristics are attributed to provide the athletic prowess so well documented in African-Americans. Not the least of coincidence seems to be the influence of the compensatory mechanisms on oxygen transport and its availability to the tissues, in response to the sickle cell gene. The reduced availability coupled with reduced myoglobin in the preponderant fast-twitch muscle fibres which are adapted for rapid energy (ATP) regeneration, all give a NET outcome of muscle anatomical and biochemical advantages which support outstanding performances in athleticism.

Existe la hipótesis de que los patrones somatogenéticos en la biología fibromuscular, las vías meta-bólicas bioquímicas, y la fisiología pulmonar, se han concentrado mediante selección natural a lo largo de siglos, en los pueblos afrocéntricos desplazados desde C1frica Occidental al Nuevo Mundo. A estas características fenotípicas y genotípicas se les atribuye las proezas atléticas, tan bien docu-mentadas en los afroamericanos. Tampoco parece ser coincidencia en lo más mínimo, la influencia de los me-canismos compensatorios de transporte de oxígeno, y su disponibilidad en los tejidos, en respuesta al gene de la célula falciforme. Esta disponibilidad reducida acoplada con la mioglobina reducida en las fibras musculares de contracción rápida preponderantes que están adaptadas para la rápida re-generación de energía (ATP), producen de conjunto un resultado neto en términos de ventajas musculares anatómicas y bioquímicas que constituyen la base de las actuaciones destacadas en el atletismo.

Myopathy with atrophy of type 2 fibers: a morphometrical analysis of three cases

Type 2 fiber atrophy is a non-specific phenomenon in several diseases, including rare cases of congenital myopathies. These myopathies manifest early in life, and are characterized by hypotonia and muscle weakness. In this report, we describe a morphometric analysis of type 1 (T1F) and type 2 (T2F) fibers in three children (0.8, 4 and 8 years old) with signs of myopathy and T2F atrophy and assess the extent of T2F involvement compared to T1F. We measured the lesser diameter of T2F and T1F processed for ATPase activity at pH 9.4, in order to determine the pattern of muscle involvement. A histogram of the frequency of muscle fiber lesser diameter was used to compare the results with other reports in the literature. Statistical analysis using the chi-square test for goodness of fit showed that the lesser diameter of T2F differed among the children (p<0.05). Hence, it was not possible to determine a pattern of T2F atrophy based on the frequency of fiber size distribution in these cases of myopathies.

Effect of testosterone propionate on the distribution pattern of calcitonin gene-related peptide in different motoneuron pools / 中国医学科学院学报

<p><b>OBJECTIVE</b>To study the effect of testosterone propionate (TP) on the distribution pattern of calcitonin gene-related peptide (CGRP) in two types of motoneuron (Mn) pools in rats.</p><p><b>METHOD</b>The double labeling of cholera toxin B subunit coupled with colloidal gold (CB-Au) retrograde identification combining with immunocytochemistry was mainly used to reveal the distribution pattern of CGRP-like immunoreactivity (CGRP-LI) and its changes in the motoneuron pools labeled by CB-Au.</p><p><b>RESULT</b>TP injected intramuscularly 28 days later significantly decreased CGRP expression in Mn pool innervating extensor digitorum longus (EDL, fast-twitch), comparing with corresponding control and castration group respectively (P < 0.001), while no significant effect on Mn pools innervating soleus (SOL, slow-twitch, P > 0.05) was observed.</p><p><b>CONCLUSION</b>EDL-Mn pool is more sensitive to testosterone propionate than SOL-Mn pool in regulating CGRP expression.</p>

Regional variations in fibre growth dynamics of myotomal and caudal fin muscles in relation to body size of a freshwater teleost, Barbus sarana (Cuv. & Val.).

The growth of red fibres in anterior and middle myotomal regions of B. sarana was mainly by hyperplasia in smaller size classes. In higher size classes, growth by hyperplasia was greater in posterior myotomal region compared to the other two myotomal regions. The growth of pink fibres in anterior myotomal regions was mainly by hypertrophy. The middle and posterior myotomal regions showed fibre growth by hyperplasia. The growth dynamics of white fibres revealed more or less similar pattern in all three myotomal regions against the somatic development. White fibres grew by hyperplasia up to 8 cm F.L. size classes and thereafter by hypertrophy. However, in > 12 cm F.L. size classes, the mean diameter of white fibres did not increase significantly. Similar pattern of growth was found in the white fibres of caudal fin muscle. It is interesting to note that the hyperplasia was mostly completed in the white fibres of the smallest fish studies, whereas, it continued to quite larger fish size in red and pink fibres. Thus, hyperplasia and hypertrophy may be responsible for growth in all fibre types in all myotomal regions in relation to somatic development in this small and medium growing species.

Effect of Regular Exercise during Recovery Period Following Steroid Treatment on the Atrophied Type II Muscles Induced by Steroid in Young Rats / 간호학회지

PURPOSE: This study was conducted to determine whether low intensity regular exercise following dexamethasone treatment could attenuate steroid-induced muscle atrophy. METHOD: 36 Wistar-rats(90-110g) were divided into six groups: control group(C), dexamethasone treatment group(D), sedentary group after normal sedentary period(C+S), sedentary group after dexamethasone treatment period(D+S), exercise group after normal sedentary period(C+E), and excercise group after dexamethasone treatment period(D+E). D, D+S, and D+E groups received dexamethasone injection(5mg/Kg) for seven days whereas C, C+S, and C+E groups received normal saline injection. Both C+E and D+E groups ran on a treadmill for 60 minutes/day(20minutes/4hours) at 15m/min and a 10degreegrade for seven recovery days. RESULT: Post-weight(body weight before muscle dissection) of D group significantly decreased by 16.03%, and that of D+E group significantly increased by 15.51% compared with pre-weight(body weight before steroid treatment). Type II muscle(plantaris and gastrocnemius) weights of D group were significantly lower than those of C group. Myofibrillar protein contents of type II muscles of D group tended to decrease comparing with C group. In D+E groups, body weights and relative weights of typeII muscles(muscle weight(mg)/post-weight(g)) tended to increase comparing with D+S group. CONCLUSION: It is suggested that steroid- induced muscle atrophy can be ameliorated through low intensity regular exercise after dexamethasone treatment.

cytopathies mitochondriales: etude clinique

Mitochondrial myopathy is a group of multisytemic disease, variable in the age at onset, frequency, clinical data, evolution and prognosis. It results from nuclear or mitochondrial DNA mutation or from defective interaction between nuclear and mitochondrial DNA. The transmission of this mitochondrial myopathy is exlusively maternal. Sometimes the mutationns are born in the maternal ovule, or early in the embryonal life. The diagnosis is suspected on clinical manifestations and is confirmed by existence of ragged - red - fibers in the muscular biopsy, and especially, by molecular study which discovers the mutation of mitochondrial DNA. The treatment is often disappointing, however some specific measures are necessary to improve the quality of patients life

Effect of thyroidectomy on fast and slow muscle fibres of rat gastrocnemius muscle.

A combined histochemical, biochemical and electrophoretic study with respect to the enzymes succnic dehydrogenase(SDH), myofibrillar adenosine triphosphatase (m-ATPase), lactate dehydrogenase (LDH) isozymes and myosin light chains was carried out to investigate the response of rat gastrocnemius muscle (medial head). Twelve weeks after thyroidectomy, the results indicated a shift from fast to slow type pattern of LDH isozymes, fibre type transformation from Type II to Type I and a decrease in SDH and m-ATPase activity. The results suggest, possible thyroidal involvement in determining the phenotypic properties of skeletal muscle.

Obesidad y diabetes mellitus tipo 2 / Obesity and type 2 diabetes mellitus

The mechanism by which obesity leads to type 2 diabetes mellitus is unknown. It is generally agreed that insulin resistance is an invariable accompaniment of obesity but that normoglycemia is maintained by compensatory hiperinsulinemia until the pancreatic B cells become unable to meet the increased demand for insulin, at which point type 2 diabetes mellitus begins. The precise cause of insulin resistance is yet to be determined, but is association with obesity has long been established. Recent data has implied free fatty acids tumoral necrosis factor - alfa, muscle fiber type II b and leptin, as a link resistance and obesity

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.