Estudo clínico, histológico, imunoistoquímico e da função lisossomal na miosite por corpos de inclusão / Clinical, histological, immunohistochemical and lysosomal function study in inclusion body myositis

A miosite por corpos de inclusão (inclusion body myositis - IBM), na sua forma esporádica, é considerada a miopatia adquirida mais comum após os 50 anos de idade. Embora seja incluída no grupo das miopatias inflamatórias, estudos recentes mostram um processo particular de degeneração muscular caracterizado por deposição anormal de agregados de proteínas nas fibras musculares e funcionamento anormal dos principais sistemas de degradação proteica. O objetivo deste estudo foi o de avaliar os aspectos clínicos, histológicos e imunoistoquímicos de pacientes com IBM. Avaliamos 18 casos com diagnóstico de IBM de dois dos principais centros de doenças neuromusculares do Brasil (25 biópsias musculares). Na tentativa de diferenciar os casos de IBM das outras miopatias inflamatórias, determinamos o padrão de expressão tecidual da p-tau (p62), alfa-sinucleína e TDP-43. Também foi avaliada a função lisossomal através da reação da fosfatase ácida (marcação da atividade lisossomal global) e determinação da marcação para LC3B (marcador de autofagia). Foi observado que a IBM predominou no sexo masculino (61% dos casos), da cor branca, com início das manifestações clínicas ao redor dos 59 anos de idade e os sintomas mais frequentes foram fraqueza muscular, instabilidade postural com quedas da própria altura, disfagia e perda ponderal, podendo ainda apresentar dispneia. O diagnóstico demorou em média 7,4 anos após o início dos sintomas e frequentemente esteve associada às seguintes comorbidades: hipertensão arterial sistêmica, diabetes mellitus tipo 2, osteopenia / osteoporose, dislipidemia e hiperuricemia / gota. O padrão de comprometimento muscular na IBM foi caracterizado por tetraparesia de predomínio proximal em membros inferiores e distal em membros superiores. Os valores séricos da creatinofosfoquinase em pelo menos uma das medições foram elevados em todos os pacientes, porém sem ultrapassar 10 vezes o limite superior da normalidade. O uso de...

Sporadic inclusion body myositis (sIBM) is considered the most common acquired myopathy affecting adults aged over 50 years. Although included in the group of inflammatory myopathies, recent studies show a particular process of muscle degeneration characterized by abnormal deposit of protein aggregates in muscle fibers and abnormal operation of the main protein degradation systems. The aim of this study was to evaluate the clinical, histological and immunohistochemical patients with IBM. We evaluated 18 cases with IBM diagnostic of two of the main centers of neuromuscular diseases in Brazil (25 muscle biopsies). In an attempt to differentiate the IBM cases of other inflammatory myopathies, we determined the pattern of tissue expression of p-tau (p62), alfa-synuclein and TDP-43. Also evaluated the lysosomal function by acid phosphatase reaction (marking global lysosomal activity) and determining the markup for LC3B (autophagy marker). It was observed that IBM was predominant in males (61% of cases), white colored, with onset of clinical manifestations around 59 years old and the most common symptoms are muscle weakness, postural instability with high falls, dysphagia and weight loss, and may also present dyspnea. The diagnosis took an average of 7.4 years after the onset of symptoms and was often associated with the following comorbidities: hypertension, type 2 diabetes mellitus, osteopenia / osteoporosis, dyslipidemia and hyperuricemia / gout. The muscular damage pattern at IBM was characterized by tetraparesis predominantly proximal lower limbs and distal upper limbs. Serum creatine kinase levels in at least one of the measurements were elevated in all patients, but not exceeding 10 times normal. Immunosuppression was not effective in patients with IBM. The IBM histological findings included diversify dystrophic changes, endomysial inflammation, as well as the occurrence of rimmed vacuoles, in addition to high frequency of mitochondrial changes. Other...

Skeletal Muscle Mitochondria and Insulin Resistance: The Role of Exercise

Insulin resistance in skeletal muscle, liver, beta-cells, fat cells, the gastrointestinal track, alpha-cells, kidneys, and brain represents the core defect in obesity or type 2 diabetes (T2D). Among them, skeletal muscle insulin resistance due to obesity or T2D is manifested by decreased glucose uptake because skeletal muscle comprises 40-50% of the total human body mass. Many previous reports indicate that T2D patients or obese insulin-resistant individuals have less mitochondria in their skeletal muscles than lean control subjects. Whether or not mitochondria in skeletal muscle play a causal role in insulin resistance has been debated. A large number of studies demonstrated that skeletal muscle insulin resistance is associated with mitochondrial deficiency including 1) reduced fatty acid oxidation and increased accumulation of lipid intermediates (e.g., FA-CoA, DAG, ceramide), 2) increased mitochondrial overload and incomplete fatty acid oxidation, and 3) increased mitochondrial oxidative stress (e.g., H2O2) in skeletal muscle. In contrast, some studies demonstrated that mitochondrial dysfunction in skeletal muscle is not responsible for insulin resistance, suggesting that 1) the development of insulin resistance in high-fat diet animals occurs with increased muscle mitochondria, and 2) fatty acid oxidation is higher in T2D patients and obese insulin-resistant individuals compared with lean control subjects. However, various types of exercises (acute vs chronic, aerobic vs resistance) are critical in the treatment and prevention of insulin resistance in obesity and T2D.

Fiebre chikungunya en México: caso confirmado y apuntes para la respuesta epidemiológica / Chikungunya fever in Mexico: confirmed case and notes on the epidemiologic response

La fiebre chikungunya (CHIK) es una enfermedad viral transmitida al ser humano por el mismo vector del dengue, el mosquito Aedes. Además de fiebre y fuertes dolores articulares, produce otros síntomas como mialgias, cefalea, náuseas, cansancio y exantema. No tiene tratamiento específico; el manejo terapéutico de los pacientes se enfoca en el alivio de los síntomas. Históricamente se han reportado brotes de grandes proporciones; incluso desde 2010 se llegó a considerar como una potencial epidemia emergente. En 2013 se introdujo a las islas del Caribe y recientemente se ha reportado en el continente americano. En este trabajo se describe el primer caso confirmado de chikungunya en México, en el municipio de Tlajomulco de Zúñiga, Jalisco, en mayo de 2014, importado de la isla Antigua y Barbuda, en el Caribe, por una mujer de 39 años de edad.

Chikungunya fever (CHIK) is a viral disease transmitted to human beings by the same vector as dengue -the Aedes mosquito. Besides fever and severe pain in the joints, it produces other symptoms such as myalgias, headache, nausea, fatigue and exanthema. There is no specific treatment for it; the therapeutic management of patients focuses on symptom relief. Historically, outbreaks of large proportions have been reported; even since 2010 it was considered to be a potential emerging epidemic. In 2013 it was introduced into the islands of the Caribbean, and it has recently been reported in the American continent. This paper describes the first confirmed case of chikungunya in Mexico -in the municipality of Tlajomulco de Zúñiga, Jalisco, in May, 2014-, which was imported from the Caribbean island of Antigua and Barbuda by a 39 year-old woman.

Effect of aerobic and resistance training; the skeletal muscle mitochondrial function in the spirit study cohort

The aim of this investigation was to examine the effect of aerobic and resistance training on the skeletal muscle mitochondrial function. Wellington Hospital New Zealand, Massey University, Wellington Campus New Zealand. Sep 2008- Sep 2011. There was a very large effect [6.7 +/- 1.2] in the AER group for BHAD activity whereas in the PRT group a large effect [2.7 +/- 1.2] for BHAD activity was observed. There was an increase in CS activity in both groups [PRT; p = 0.007, AER; p=0.03] however, the activity increase was more in the PRT group [effect size = 1.8 +/- 1.3]. COX activity was raised in both groups as well though the effect size in the PRT group was 2.3 +/- 1.2 meaning a very large change with PRT exercise compared to a moderate effect [1.0 +/- 1.2] with AER exercise. Overall these findings suggest that both PRT and AER exercise can be effective therapeutic modalities for the induction of changes at the cellular level in muscle of people with T2DM

Exercise training in hypoxia prevents hypoxia induced mitochondrial DNA oxidative damage in skeletal muscle / 生理学报

This study was undertaken to investigate the effect of exercise training on mitochondrial DNA (mtDNA) oxidative damage and 8-oxoguanine DNA glycosylase-1 (OGG1) expression in skeletal muscle of rats under continuous exposure to hypoxia. Male Sprague-Dawley rats were randomly divided into 4 groups (n = 8): normoxia control group (NC), normoxia training group (NT), hypoxia control group (HC), and hypoxia training group (HT). The hypoxia-treated animals were housed in normobaric hypoxic tent containing 11.3% oxygen for consecutive 4 weeks. The exercise-trained animals were exercised on a motor-driven rodent treadmill at a speed of 15 m/min, 5% grade for 60 min/day, 5 days per week for 4 weeks. The results showed that, compared with NC group, hypoxia attenuated complex I, II, IV and ATP synthase activities of the electron transport chain, and the level of mitochondrial membrane potential in HC group (P < 0.05 or P < 0.01). Moreover, hypoxia decreased mitochondrial OGG1, MnSOD, and GPx activities (P < 0.05 or P < 0.01), whereas elevated reactive oxygen species (ROS) generation and the level of 8-oxo-deoxyguanosine (8-oxodG) in mtDNA (P < 0.01). Furthermore, hypoxia attenuated muscle and mitochondrial [NAD⁺]/ [NADH] ratio, and SIRT3 protein expression (P < 0.05 or P < 0.01). Compared with HC group, exercise training in hypoxia elevated complex I, II, IV and ATP synthase activities, and the level of mitochondrial membrane potential in HT group (P < 0.05 or P < 0.01). Moreover, exercise training in hypoxia increased MnSOD and GPx activities and mitochondrial OGG1 level (P < 0.01), whereas decreased ROS generation and the level of 8-oxodG in mtDNA (P < 0.01). Furthermore, exercise training in hypoxia increased muscle and mitochondrial [NAD⁺]/[NADH] ratio, as well as SIRT3 protein expression (P < 0.05 or P < 0.01). These findings suggest that exercise training in hypoxia can decrease hypoxia-induced mtDNA oxidative damage in the skeletal muscle through up-regulating exercise-induced mitochondrial OGG1 and antioxidant enzymes. Exercise training in hypoxia may improve hypoxia tolerance in skeletal muscle mitochondria via elevating [NAD⁺]/[NADH] ratio and SIRT3 expression.

Effect of eccentric training on mitochondrial function and oxidative stress in the skeletal muscle of rats

The objective of the present study was to investigate the effects of eccentric training on the activity of mitochondrial respiratory chain enzymes, oxidative stress, muscle damage, and inflammation of skeletal muscle. Eighteen male mice (CF1) weighing 30-35 g were randomly divided into 3 groups (N = 6): untrained, trained eccentric running (16°; TER), and trained running (0°) (TR), and were submitted to an 8-week training program. TER increased muscle oxidative capacity (succinate dehydrogenase and complexes I and II) in a manner similar to TR, and TER did not decrease oxidative damage (xylenol and creatine phosphate) but increased antioxidant enzyme activity (superoxide dismutase and catalase) similar to TR. Muscle damage (creatine kinase) and inflammation (myeloperoxidase) were not reduced by TER. In conclusion, we suggest that TER improves mitochondrial function but does not reduce oxidative stress, muscle damage, or inflammation induced by eccentric contractions.

Effects of carnitine on respiratory chain and metabolism of oxygen radical in mitochondria of skeletal muscle after exhaustive running in training rat / 生理学报

The aim of the present study was to investigate the effect of carnitine on function of respiratory chain and metabolism of oxygen radical in mitochondria of skeletal muscle after exhaustive running in training rats. Forty male Wistar rats were randomly divided into 4 groups (n = 10): control, carnitine, training and training + carnitine groups. The training and training + carnitine groups received 6-week treadmill training, whereas carnitine and training + carnitine groups were administered intragastrically with carnitine (300 mg/kg per day, 6 d/week) for 6 weeks. After exhaustive running, all the rats from 4 groups were sacrificed to obtain quadriceps muscles samples, and muscle mitochondria were extracted by differential centrifugation. Spectrophotometric analysis was used to evaluate activities of respiratory chain complexes (RCC) I-IV, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the content of malondialdehyde (MDA) in the skeletal muscle mitochondria. The results showed that, compared with the control group, the carnitine group exhibited increased RCCI and RCCIII activities (P < 0.05), the training + carnitine group exhibited increased RCCI, RCCIII and RCCIV activities (P < 0.05 or 0.01). Moreover, RCCIII activity in the training + carnitine group was higher than that in training group (P < 0.05). Compared with the control group, the carnitine, training and training + carnitine groups showed increased SOD activities ( P < 0.01), the carnitine and training + carnitine groups showed increased GSH-Px activities ( P < 0.01), the carnitine, training and training + carnitine groups showed increased MDA contents (P < 0.05 or 0.01). The SOD and GSH-Px activities in training + carnitine group were higher than those in training group (P < 0.01), and the MDA level in the training + carnitine group was higher than that in the carnitine and training groups (P < 0.01). These results suggest that training and carnitine can increase function of respiratory chain, antioxidation and lipid peroxidation tolerance capacity in skeletal muscle mitochondria, and the improving effects of training and carnitine are synergistic.

Assessment of mitochondrial toxicity induced by zidovudine and adefovir dipivoxil in rats / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To explore the mitochondrial toxicities induced by zidovudine (AZT) and adefovir dipivoxil (ADV) antiviral drugs using a rat model system.</p><p><b>METHODS</b>Twelve healthy Sprague-Dawley rats were randomly divided into three equal groups and treated by oral gavage with zidovudine (125 mg/kg/day), adefovir (40 mg/kg/day), or saline (equal volume) for 28 days. The rats' body weights were measured once a week, and blood was collected every two weeks for blood and biochemical tests. All animals were sacrificed at the end of treatment, and liver, kidney, skeletal muscle, and cardiac muscle were collected by necropsy. Mitochondria were isolated from the respective tissue samples, and the activities of respiratory chain complexes were measured. DNA was purified from each sample and the mitochondrial DNA (mtDNA) content was monitored by quantitative real time PCR. Mitochondrial morphology was analyzed under electron microscope.</p><p><b>RESULTS</b>No significant adverse effects, including body weight loss, abnormal blood or biochemistry, were observed in rats treated with AZT or ADV. The activities of mitochondrial cytochrome c oxidase in liver and cardiac muscle were slightly decreased in rats treated with AZT (liver: 9.44+/-3.09 vs. 17.8+/-12.38, P?=?0.21; cardiac muscle: 32.74+/-5.52 vs. 24.74+/-20.59, P?=?0.28; kidney: 4.42+/-1.53 vs. 14.45+/-13.75, P?=?0.18; skeletal muscle: 33.75+/-8.74 vs. 40.04+/-2.49, P?=?0.45). The mtDNA content was significantly decreased in cardiac muscle of AZT-treated rats (cardiac muscle: 0.15+/-0.13 vs. 0.32+/-0.42, P?=?0.85). The morphology of mitochondria in liver, kidney, skeletal muscle, and cardiac muscle was significantly altered in the AZT-treated rats and included disappearance of the outer membrane, severely damaged structure, and swollen or completely absent cristae. No obvious effects were noted in the ADV- or saline-treated rats.</p><p><b>CONCLUSION</b>Significant adverse effects related to mitochondrial toxicity were observed in rats treated with AZT. The slightly decreased mtDNA content in ADV-treated rats may suggest that this antiviral drug can also cause mitochondrial toxic effects.</p>

Value of dynamic ³¹P magnetic resonance spectroscopy technique in in vivo assessment of the skeletal muscle mitochondrial function in type 2 diabetes / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Phosphorous magnetic resonance spectroscopy ((31)P-MRS) has been successfully applied to study intracellular membrane compounds and high-energy phosphate metabolism. This study aimed to evaluate the capability of dynamic (31)P-MRS for assessing energy metabolism and mitochondrial function in skeletal muscle from type 2 diabetic patients.</p><p><b>METHODS</b>Dynamic (31)P-MRS was performed on 22 patients with type 2 diabetes and 26 healthy volunteers. Spectra were acquired from quadriceps muscle while subjects were in a state of rest, at exercise and during recovery. The peak areas of inorganic phosphate (Pi), phosphocreatine (PCr), and adenosine triphosphate (ATP) were measured. The concentration of adenosine diphosphate (ADP) and the intracellular pH value were calculated from the biochemistry reaction equilibrium. The time constant and recovery rates of Pi, PCr, and ADP were analyzed using exponential curve fitting.</p><p><b>RESULTS</b>As compared to healthy controls, type 2 diabetes patients had significantly lower skeletal muscle concentrations of Pi, PCr and β-ATP, and higher levels of ADP and Pi/PCr. During exercise, diabetics experienced a significant Pi peak increase and PCr peak decrease, and once the exercise was completed both Pi and PCr peaks returned to resting levels. Quantitatively, the mean recovery rates of Pi and PCr in diabetes patients were (10.74 ± 1.26) mmol/s and (4.74 ± 2.36) mmol/s, respectively, which was significantly higher than in controls.</p><p><b>CONCLUSIONS</b>Non-invasive quantitative (31)P-MRS is able to detect energy metabolism inefficiency and mitochondrial function impairment in skeletal muscle of type 2 diabetics.</p>

Effects of different hypoxic training modes on activities of mitochondrial antioxidants and respiratory chain complex in skeletal muscle after exhaustive running in rat / 生理学报

The present study was aimed to investigate the effect of hypoxic training on mitochondrial antioxidants and activities of respiratory chain complexes in mitochondria of skeletal muscle in rats. Forty healthy male Wistar rats were randomized to 5 groups (n=8): living low-training low (LoLo), living high-training high (HiHi), living high-training low (HiLo), living low-training high (LoHi), and living high-exercise high-training low (HiHiLo). All the animals were subjected to 5-week training in normoxic (atmospheric pressure=632 mmHg, altitude of about 1 500 m) or hypoxic environment (atmospheric pressure=493 mmHg, simulated altitude of about 3 500 m). Before exhaustive running, the animals stayed in normoxia for 3 d. Skeletal muscles were prepared immediately after exhaustive running. Muscle mitochondria were extracted by differential centrifugation. Spectrophotometric analysis was used to evaluate activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA) level and respiratory chain complex (C) I-III activities in muscle homogenate and mitochondria. Results showed that SOD, GSH-Px, CAT activities and MDA level in skeletal muscle homogenate in HiHi and HiHiLo groups were significantly increased (P<0.05 or P<0.01) compared with those in LoLo group. Muscle mitochondrial MDA level in HiHi and HiHiLo groups was significantly lower (P<0.01), while activities of SOD, GSH-Px and CAT were remarkably higher (P<0.01) than those in LoLo group. Meanwhile, C I-III activities in HiHi and HiHiLo groups were increased significantly (P<0.01), and C II activity in HiLo group also was increased remarkably (P<0.01) compared with those in LoLo group. These results suggest that HiHiLo might be an ideal hypoxic training mode.

Pathologic changes of the palatopharyngeal muscles in patients with obstructive sleep apnea hypopnea syndrome of different degrees / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To study the pathologic changes of the palatopharyngeal muscles with transmission electronmicroscopy (TEM) in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), the role of the above muscle in OSAHS pathogenesis was discussed.</p><p><b>METHODS</b>Thirty-eight palatopharyngeal muscle from OSAHS patients receiving uvulopalatopharyngoplasty (UPPP) were collected in in-patient department of Chinese Medical University and five palatal tumor patients receiving resection without snoring were chosen as the control. The palatopharyngeal muscle fiber and the feature of changes in mitochondrial morphology were observed by TEM.</p><p><b>RESULTS</b>The pathological changes were not observed in the normal control group. The muscle fibers were regularly arranged, and the mitochondrial between muscles were normal. The palatopharyngeal myofibrillar in mild OSAHS group was regularly arranged. The Z lines were straight, and most mitochondria structure were normal. In the moderate group, the myofibrillar was disorganized, and the Z lines were shortened or distorted. The myofibrillar in severe group was disorganized, similar to point-like or flake, and the Z lines and the structures of sarcomeres were disappeared. And organelle were disintegrated and mitochondria were disappeared similar to flocculent. There existed obvious fatty infiltration in the palatopharyngeal muscle. In the control, mild, moderate and severe group, pharyngeal muscle fiber disarrangement of the occurrence rate was 0, 2/10, 8/13, 14/15, the occurrence rate of mitochondrial degeneration was 0, 2/10, 8/13, 14/15, increased with the severity of the ultrastructural changes in the trend of increasing incidence.</p><p><b>CONCLUSIONS</b>The degree of OSAHS is correlated with the pathological changes of palatopharyngeal muscles. Incidence of myopathy is an important part of OSAHS secondary to chronic intermittent hypoxia in OSAHS and other pathological lesions, but also an important reason for increasing pharyngeal collapse.</p>

Detection of bovine, goat, pig and chicken derived ingredients in animal products with universal PCR-microarray method / 生物工程学报

We analyzed the sequence of vertebrate molecular marker genes, then we selected the mitochondrial DNA (mtDNA) 16S rRNA gene as marker gene. In order to detect four kinds of animal-derived ingredients, which including bovine, goat, pig and chicken. We utilized a pair of universal primers, designed four sets of species-specific microarray probes and two pairs of quality control probes. We optimized the PCR amplifications and hybridization conditions, therefore these four kinds of animal-derived ingredients could be rapid and accurate detected by this approach. The detection limits were all reaches 1 pg. We established the detection platform of these four kinds of animal-derived ingredients. This universal PCR-microarray assay provides a new method for the identification of animal-derived ingredients in the import-export field.

Multiplex fluorescent real-time PCR detection of bovine, goat and sheep derived materials in animal products / 生物工程学报

We designed the specific primers and TaqMan probes targeting cytochrome b genes of mitochondrial DNA from bovine, goat and sheep. We used different fluorescents to label the probes. After optimization of reaction conditions, we set up a multiplex fluorescent real-time PCR method to detect bovine, goat and sheep derived materials, simultaneously. We finished the detection tests of 17 kinds of animal DNA and 200 DNA samples from different sources with the developed method and the National Standard GB/T 20190Y-2006 routine PCR method. The coincidence rate of these two methods was 100%. Without electrophoresis or restriction digestion, the developed method could reduce the test time to one third as routine PCR and identify three kinds of animal derived materials including bovine, goat and sheep in one reaction. The developed method was approximately 10 times more sensitive than routine PCR, and was applicable to identifications of bovine, goat and sheep derived materials in feed stuff, meat, milk, pelt and grease, etc. The study showed that the developed real-time PCR method is a rapid, sensitive and efficacious detection assay for bovine, goat and sheep derived materials in animal products.

Difference in oxygen uptake in skeletal muscles between plateau zokor (Myospalax rufescens baileyi) and plateau pika (Ochotona curzoniac) / 生理学报

To investigate the difference between the functions of oxygen uptake in skeletal muscle and living habits of plateau zokor (Myospalax rufescens baileyi) and plateau pika (Ochotona curzoniac), the microvessel densities (MVD) of skeletal muscle of plateau zokor, plateau pika and Sprague-Dawley (SD) rat were measured by immunohistochemical staining; the numerical density on area (N(A)) of mitochondria, and surface density (S(V), external surface area density of mitochondria per unit volume of skeletal muscle fiber) were obtained by stereo microscope technique; mRNA levels of myoglobin (Mb) in skeletal muscle were determined by real-time PCR, and the contents of Mb protein in skeletal muscle were determined by spectro-photometer. The results showed that MVD, N(A) and S(V) of mitochondria in skeletal muscle of plateau pika were significantly lower than those of plateau zokor and SD rat (P<0.05). The mRNA levels of Mb gene in skeletal muscle of plateau zokor and plateau pika were notably higher than that of SD rat (P<0.05). There were significant differences in the contents of Mb among these three species, and plateau zokor and SD rat presented the highest and the lowest value, respectively (P<0.05). The results suggest that even though plateau zokor inhabits in the hypoxia environment, most of its skeletal muscle fiber are red muscle fiber. While most of skeletal muscle fibers of plateau pika are white muscle fibers. This kind of white muscle has low MVD, N(A) and S(V) of mitochondria and less content of Mb compared with the red one, suggesting it obtains most energy from aerobic oxidation. The above-mentioned differences in skeletal muscles may be related to not only the different species, but also the different living habits of these two high altitude species.

Endurance training attenuates the bioenergetics alterations of rat skeletal muscle mitochondria submitted to acute hypoxia: role of ROS and UCP3 / 生理学报

The physiological significance of skeletal muscle mitochondrial uncoupling protein 3 (UCP3) in hypoxia is elusive. In the current study, UCP3 mRNA and protein expressions were investigated along with mitochondrial respiratory function, reactive oxygen species (ROS) generation, as well as manganese superoxide dismutase (MnSOD) expression in rat skeletal muscle with or without endurance training after an acute and severe hypobaric hypoxia exposure for different time. Acute hypoxia induced a series of impairments in skeletal muscle mitochondrial bioenergetics. In untrained rats, UCP3 protein content increased by 60% above resting level at 4 h hypoxia, whereas MnSOD protein content and activity were unaltered. UCP3 upregulation increased mitochondrial uncoupling respiration thus reducing O2(.-) generation, but inevitably decreased ATP production. Training decreased acute hypoxia-induced upregulation of UCP3 protein (67% vs 42%) in rat skeletal muscle. ROS production in trained rats also showed a dramatic decrease at 2 h, 4 h and 6 h, respectively, compared with that in untrained rats. MnSOD protein contents and activities were significantly (50% and 34%) higher in trained than those in untrained rats. Training adaptation of MnSOD may enhance the mitochondrial tolerance to ROS production, and reduce UCP3 activation during severe hypoxia, thus maintaining the efficiency of oxidative phosphorylation. In trained rats, mitochondrial respiratory control (RCR) and P/O ratios were maintained relatively constant despite severe hypoxia, whereas in untrained rats RCR and P/O ratios were significantly decreased. These results indicate that (1) UCP3 mRNA and protein expression in rat skeletal muscle are upregulated during acute and severe hypobaric hypoxia, which may reduce the increased cross-membrane potential (Deltapsi) and thus ROS production; (2) Endurance training can blunt hypoxia-induced UCP3 upregulation, and improve mitochondrial efficiency of oxidative phosphorylation due to increased removal of ROS.

PCR-mtDNA for detecting components of duck origin in foodstuff and feedstuff / 生物工程学报

Mitochondrial cytochrome oxidase III (COIII) of duck was successfully amplified by PCR-mtDNA with duck muscle DNA as the template (GenBank Accession No. DQ655706). Cloning sequence analysis shows that the 784 bp nucleotides of COIII gene were contained. Through homology analysis, we confirmed that the cytochrome oxidase III (COIII) was relatively conservative. The method of PCR-mtDNA can be designed to detect the components of duck origin. And then, the method of PCR can be applied to amplify with the muscle DNA of various animal and feedstuff as the template, repeated verification, the primer (P3, P4) with strong specificity and good stability is screened, which can only amplify the sequence of duck. The special sequence contains 226 bp, the amplified product of 226 bp was sequenced and analyzed, it showed 100% homology with duck mtDNA COIII gene, which proved the accuracy of the special primer. The test that used different concentration of DNA with P3 and P4 is the sensitive experiment by PCR. The result showed that the primer has much specialty and rather sensitivity. So it is a way to detect the duck origin in the muscle of various animal and feedstuff.

Mitochondrial myopathies-clinicopathological features and diagnostic modalities.

Mitochondrial myopathy is the term applied to a clinically and biochemically heterogeneous group of disorders which have multisystem involvement. The concept was introduced by Luft in 1962. These are due to genetic defects in the respiratory chain enzymes which are detected by histochemical, immunohistochemical stains, molecular biological studies and ultrastructural studies on muscle biopsy. Classification of the disorders can be genetic, based on defects of respiratory enzyme complexes or on the basis of the clinical syndromes. Due to the extremely variable clinical presentations of these disorders, a complete clinical and laboratory workup involving strict diagnostic criteria is essential.

Skeletal muscle mitochondrial dysfunction & diabetes.

Skeletal muscle insulin resistance is a key contributor to the pathophysiology of type 2 diabetes. Recent studies have shown that insulin resistance in a variety of conditions including type 2 diabetes, ageing and in offspring of type 2 diabetes is associated with muscle mitochondrial dysfunction. The important question is whether insulin resistance results from muscle mitochondrial dysfunction or vise versa. Gene array studies from muscle biopsy samples showed that transcript levels of several genes, especially OXPHOS genes are altered in type 2 diabetic patients during poor glycaemic control but many of these alterations are normalized by insulin treatment suggesting that reduced insulin action is a factor involved in muscle mitochondrial dysfunction. Moreover, insulin infusion while maintaining glucose and amino acid levels results in increase in muscle mitochondrial gene transcript levels and ATP production indicating that insulin is a key regulator of muscle mitochondrial biogenesis. At a similar post-absorptive insulin levels both type 2 diabetic patients and non diabetic controls have similar muscle mitochondrial ATP production but increasing insulin from low to high levels stimulate ATP production only in non diabetic people but not in the diabetic people. The lack of muscle mitochondrial response to insulin in type 2 diabetic patients is likely to be related to insulin resistance and reduced substrate utilization.

Age-dependent mitochondrial DNA 4977bp depletion in human skeletal muscle / 法医学杂志

OBJECTIVE@#To explore depletion of human mitochondrial DNA 4977-bp and its relation with aging.@*METHODS@#Total DNA (nuclear and mtDNA) was extracted from 100mg muscle tissue. UV light illumination of ethidium bromide-stained PCR products was used to study the depletion of mtDNA (wild-type or mutant).@*RESULTS@#The proportions of mtDNA depletion in human skeletal muscle could be determined. The frequency of mtDNA 4977-bp depletion in different age groups (0-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89, 90-99) was: 0%, 0%, 0.003%, 0.011%, 0.015%, 0.033%, 0.038%, 0.062%, 0.069%, and 0.091%, respectively.@*CONCLUSION@#Our findings suggest that the frequency of the mtDNA4977 depletion in human skeletal muscle increases with age. It might be useful for human age estimation.

Precipitation of stroke-like event by chickenpox in a child with MELAS syndrome.

The mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes syndrome (MELAS) is a rare congenital disorder of mitochondrial DNA (mtDNA). Herein we report a case of MELAS, whose second stroke-like episode was provoked by chickenpox. A point mutation at nucleotide (nt) 3243 in mtDNA supported the diagnosis of MELAS in this case. History of myopathy, the presence of lesions that did not conform to accepted distributions of vascular territories on cranial magnetic resonance imaging (MRI), normal result of cranial magnetic resonance angiography, hyperintensity on diffusion weighted MRI and apparent diffusion coefficient mapping indicating the presence of vasogenic edema in the fresh stroke-like lesion, and mitochondrial DNA analysis helped to exclude the diagnosis of ischemic cerebral infarction which can also be induced by chickenpox.