[Effects of exercises with different durations and intensities on mitochondrial autophagy and FUNDC1 expression in rat skeletal muscles].

The aim of the present study was to investigate the effects of exercises with different durations and intensities on mitochondrial autophagy and FUNDC1 in rat skeletal muscles. Sixty male Sprague-Dawley rats were randomly divided into 2- and 4-week control groups (Con), moderate-intensity exercise groups (M-ex groups, treadmill exercise, 16 m/min, 1 h/d, 6 d/week), and high-intensity exercise groups (Hi-ex groups, treadmill exercise, 35 m/min, 20 min/d, 6 d/week). The bilateral soleus muscles were separated after the intervention, and paraffin sections were prepared for transmission electron microscopy. ELISA method was used to detect the content of citrate synthase (CS). The co-localizations of microtubule-associated protein 1 light chain 3 (LC3)/cytochrome c oxidase IV (COX-IV), FUNDC1/COX-IV and LC3/FUNDC1 were observed by immunofluorescent staining in frozen sections. The skeletal muscle mitochondria were extracted, and the expression of autophagy-related proteins, including AMPKα, p-AMPKα, Unc-51 like kinase 1 (ULK1), FUNDC1, LC3 and p62, were detected by Western blot. The results showed that exercise increased mitochondrial function, i.e. peroxisome proliferator-activated receptor γ co-activator-1α (PGC-1α), COX-I protein expression levels and CS content. There was no difference of mitochondrial function parameters between 2-week M-ex and 2-week Hi-ex groups, while mitochondrial function of 4-weeks Hi-ex group was significantly lower than that of 4-week M-ex group. Under the same exercise intensity, mitochondrial autophagy activation in skeletal muscle of 4-week exercise was higher than that in 2-week exercise group; Under the same duration of exercise, mitochondrial autophagy activation of Hi-ex group was higher than that in M-ex group. Both 2- and 4-week exercise intervention increased LC3/COX-IV, COX-IV/FUNDC1, and FUNDC1/LC3 co-localizations. Exercise increased LC3-II/LC3-I ratio, down-regulated p62 protein expression level, up-regulated FUNDC1, ULK1 protein expression levels and AMPKα phosphorylation, and the changes of these proteins in 4-week Hi-ex group were significantly greater than those in 4-week M-ex group. These results suggest exercise induces mitochondrial autophagy in skeletal muscles, and the activity of autophagy is related to the duration and intensity of exercise. The induction mechanism of exercise may involve the mediation of FUNDC1 expression through AMPK-ULK1 pathway.

Increased serum visfatin level is associated with fat deposition of the lumbar spine in ankylosing spondylitis patients.

Objectives: To assess the serum visfatin levels in patients with ankylosing spondylitis (AS), as well as its correlation with fat deposition of the lumbar spine. Methods: Serum visfatin levels were detected by enzyme-linked immunosorbent assay (ELISA) in 50 AS patients and 75 sex-and age-matched healthy controls. The clinical and laboratory indexes of AS patients were recorded, and the lumbar spine magnetic resonance scan was performed to evaluate the lumbar spine fat deposition in AS patients. The level of serum visfatin and its correlation with lumbar fat deposition were analyzed, and the risk factors of AS lumbar MRI fat deposition were evaluated by Logistic regression. Results: Serum visfatin levels in AS patients were elevated compared with that in healthy controls (p < 0.001), and were more significant in patients with fat deposition and syndesmophyte formation (p = 0.017 and p = 0.014, respectively). Serum visfatin levels were positively correlated with CRP, BASDAI, mSASSS and fat deposition (all p < 0.05). Age (OR = 1.085, 95% CI: 1.005-1.173, p = 0.038), disease duration (OR = 1.267, 95% CI: 1.017-1.578, p = 0.035), and visfatin (OR = 1.846, 95% CI: 1.004-3.393, p = 0.048) were risk factors for fat deposition in AS patients. Conclusions: The level of serum visfatin in AS patients is significantly increased, which is associated with fat deposition on lumbar MRI. Elevated visfatin level is an independent risk factor for AS lumbar fat deposition.

Synergistic Effects of Multiple Environmental Factors on Degradation of Silicone Rubber Seals under Marine Atmosphere.

In this research, the degradation behavior and failure mechanism of silicone rubber seal rings under the synergistic effects of multiple factors in the marine atmosphere are fully investigated. Firstly, four aging factors of air, temperature, compressive stress, and chemical medium were determined by analyzing the service environment profile of silicone rubber seal under a marine atmosphere environment. Secondly, to better simulate the actual service environment of silicone rubber and shorten the test period, an artificially accelerated aging test was designed and carried out in the laboratory. In this paper, temperature is utilized as the accelerating stress. According to the results of the pre-test, the accelerating stress level is finally determined to be 110-150 ∘C. In addition, the compression set applied is consistent with the constant compression permanent deformation value of 28% of the silicone rubber in the actual service process. Finally, through the macroscopic physical properties and microstructure analysis of the samples before and after aging, the corresponding test results are given, and the failure mechanism is analyzed and discussed in detail. Through the above test results and discussion, it can be concluded that the aging process of multi-factor coupling on the lower silicone rubber seal ring is uneven, and its aging process is not a simple superposition of multiple environmental factors. More importantly, the above test data and results are of great significance for evaluating the service life of silicone rubber seals, which can be utilized in the future to improve the reliability and durability of related equipment in the marine environment.

[Change in gastrocnemius dystrophin and metabolic enzymes and increase in high-speed exhaustive time induced by hypoxic training in rats].

The aim of the present study was to explore the changes and roles of dystrophin and membrane permeability in hypoxic training. Seventy-two 8-week-old Sprague Dawley (SD) rats were randomly divided into 4 groups, normoxic non-train (NC), normoxic train (NT), hypoxic non-train (HC), and hypoxic train (HT) groups. The rats of each group were randomly divided into three subgroups, non-exhaustive, low-speed exhaustive test and high-speed exhaustive test subgroups. Rats in hypoxia groups lived and were trained in a condition of 12.7% oxygen concentration (equal to the 4 300 m altitude). NT and HT groups received 4 weeks of training exercise. Then the rats in all non-exhaustive subgroups were sacrificed, and gastrocnemii were sampled for the measurements of lactate dehydrogenase (LDH), succinatedehydrogenase (SDH), malate dehydrogenase (MDH) activities. Moreover, serum LDH activity was analyzed. Low-speed exhaustive test and high-speed exhaustive test subgroups received exhaustive tests with 20 (71% VO2max) and 30 m/min speed (86% VO2max), respectively, and their exhaustive times were recorded. The results showed that, compared with normoxic groups, the weights in hypoxia groups exhibited slower increase. The level of dystrophin in HT group without exhaustion test didn't change significantly. The muscle MDH activities were markedly affected by the different oxygen concentration, training and their interaction (P < 0.05), whereas the muscle LDH activities were only affected by the different oxygen concentration (P < 0.05). Serum LDH activities were affected by the interaction of the different oxygen concentration and training (P < 0.05), showing decreased muscle LDH and increased blood LDH activities. The exhaustion time were markedly affected by the different test speed, training and their interaction (P < 0.05), and also affected by the interaction of the different oxygen concentration and training (P < 0.05), but didn't affected by oxygen concentration. The exhaustive time of HT high-speed exhaustive test subgroup was more than NT high-speed exhaustive test subgroup in 30 m/min exhaustion test. Compared with NT high-speed exhaustive test subgroup, HT high-speed exhaustive test subgroup had an earlier fatigue in the test, but had a rapid recovery. These results suggested that hypoxic training can effectively increase the rats' high-speed exhaustive time. The mechanism may be related to an increase in serum LDH caused by the increased membrane permeability after hypoxic training.

[Effects of heavy-load exercise on skeletal muscle cells apoptosis and mechanisms of mitochondrial apoptosis in rats].

OBJECTIVE: To analyze the molecular mechanisms of skeletal muscle cells apoptosis induced by heavy-load exercise with Omi as the entry point. METHODS: One hundred and twenty-six adult SD rats were randomly divided into five groups: control group(C), eccentric exercise group (E), simple blocking group (U), DMSO group (D) and exercise block group (EU). In addition to the C group, the other four groups were randomly divided into 0 h after experiment, 12 h after experiment, 24 h after experiment, 48 h after experiment and 72 h after experiment with 6 rats in each group. E and EU group were submitted to a heavy-load exercise on a treadmill down a 16° decline, 16 m/min for 90 minutes. U, D and EU group were one-time intervened with drugs. U and EU groups were intraperitoneally injected with 1.5 µmol/kg ucf-101, D group were intraperitoneally injected with 1.5 µmoL/kg 0.5% DMSO. The rats were sacrificed in batches at different time points after experiment, then the soleus were saved to detect the Caspase-3,-8,-9,-12 activities and protein expressions of Omi and XIAP. RESULTS: Compared with group C, the mitochondrial distribution and morphology appeared the typical ultrastructure pathological changes, the opening degree of MPTP was increased significantly (P＜0.01) or (P＜0.05), protein expressions of Omi and XIAP were increased significantly (P＜0.01 or P＜0.05), the activities of Caspase-9 and Caspase-3 were increased significantly (P＜0.01 or P＜0.05) in group E. Compared with group C, there was no significant difference in XIAP protein and caspase-9, - 3 activities in group U and Group D. The change trend of XIAP protein and Caspase-9, - 3 activities was the same as those between EU group and E group, but the change range of XIAP protein in EU group was significantly higher than that in E group (P＜0.01), and the change ranges of caspase-9, - 3 activities in EU group were significantly lower than those in E group (P＜0.01). CONCLUSION: A single heavy-load exercise can induce changes in the mitochondria morphology and structure in rats, open the high permeability of MPTP, and improve the expression of Omi protein, then through its downstream XIAP-Caspase pathway, start the mitochondrial apoptosis pathway mediated by caspase-9, and finally lead to myocyte apoptosis. The inhibition of Omi can reduce the cell apoptosis level of motor induced skeletal muscle cells.

A Review of the Role of Endo/Sarcoplasmic Reticulum-Mitochondria Ca2+ Transport in Diseases and Skeletal Muscle Function.

The physical contact site between a mitochondrion and endoplasmic reticulum (ER), named the mitochondria-associated membrane (MAM), has emerged as a fundamental platform for regulating the functions of the two organelles and several cellular processes. This includes Ca2+ transport from the ER to mitochondria, mitochondrial dynamics, autophagy, apoptosis signalling, ER stress signalling, redox reaction, and membrane structure maintenance. Consequently, the MAM is suggested to be involved in, and as a possible therapeutic target for, some common diseases and impairment in skeletal muscle function, such as insulin resistance and diabetes, obesity, neurodegenerative diseases, Duchenne muscular dystrophy, age-related muscle atrophy, and exercise-induced muscle damage. In the past decade, evidence suggests that alterations in Ca2+ transport from the ER to mitochondria, mediated by the macromolecular complex formed by IP3R, Grp75, and VDAC1, may be a universal mechanism for how ER-mitochondria cross-talk is involved in different physiological/pathological conditions mentioned above. A better understanding of the ER (or sarcoplasmic reticulum in muscle)-mitochondria Ca2+ transport system may provide a new perspective for exploring the mechanism of how the MAM is involved in the pathology of diseases and skeletal muscle dysfunction. This review provides a summary of recent research findings in this area.

[Effects of acupuncture on endoplasmic reticulum pathway in exercise-induced skeletal muscle damage in rats and its mechanism].

Objective: To observe the effects of acupuncture on the endoplasmic reticulum (ER) functional enzymes sarcoplasmic reticulum Ca2+-ATPase (SERCA), protein disulfide isomerase (PDI), glucose-regulated protein 78(GRP78) and PERK pathways in rats with exercise-induced skeletal muscle damage, and to explore the mechanisms of acupuncture in preventing and treating exercise-induced skeletal muscle damage. Methods: Eight-week-old male SD rats were randomly divided into control group (group C, n=6), exercise group (group E, n=30), acupuncture group (group A, n=30) and exercise acupuncture group (group EA, n=30). Among them, the E and EA group were established an exercise-induced skeletal muscle damage model by a single eccentric exercise, and acupuncture intervention was applied 0.5 cm above the Achilles tendon of the rat's calf immediately after EA exercise, and in group A, acupuncture intervention was applied during the same period. Each group was divided into 0 h/12 h/24 h/48 h/72 h (n=6) according to different sampling time points after exercise and acupuncture intervention, and soleus muscle was collected at the corresponding time for index test. The ultrastructure of muscle fibers was observed by transmission electron microscopy; the contents of SERCA and PDI were determined by ELISA; and the expressions of ER stress marker proteins GRP78 and p-PERK and p-eIF2α were detected by Western blot. Results: Compared with group C, there were no significant differences in the indicators of group A at all time points (P＞ 0.05), the ultrastructure of muscle fibers in group E showed different damages, SERCA content was significantly decreased from 0 h to 48 h (P＜0.05), PDI content was significantly increased from 0 h to 72 h (P＜0.05), GRP78 expression was significantly increased from 0 h to 72 h (P＜0.05), p-PERK expression was significantly increased from 0 h to 24 h (P＜0.05), and p-eIF2α expression was consistent with p-PERK. Compared with the corresponding times in group E, the ultrastructure of muscle fibers in group EA was significantly alleviated, SERCA content was significantly increased from 48 h and 72 h (P＜0.05), PDI content was significantly increased from 0 h to 72 h (P＜0.05), and GRP78 expression was significantly decreased from 0 h to 72 h (P＜0.05). Conclusion: Acupuncture can effectively ameliorate exercise-induced skeletal muscle damage and alleviate ER stress after a large load eccentric exercise. The mechanism of them may be related to the up-regulation of protein disulfide isomerase PDI and the inhibition of ER stress PERK pathway.

[TGF-ß1/ERK/CTGF pathway involved in effect of acupuncture on exercise-induced skeletal muscle fibrosis].

OBJECTIVE: To observe the changes of the skeletal muscle fibrosis and changes of transforming growth factor-ß1(TGF-ß1)/ extracellular signal-regulated kinase (ERK) / connective tissue growth factor (CTGF)pathway in rats after long-term eccentric exercise and acupuncture intervention, so as to explore the mechanism of acupuncture in regulating exercise-induced skeletal muscle fibrosis. METHODS: A total of 30 male SD rats were randomly divided into normal control, exercise and acupuncture group, with 10 rats in each group. The rat model of skeletal muscle fibrosis was established by eccentric exercise for 3 weeks. After exercise trained every time, the rats of the acupuncture group received acupuncture stimulation by holding the acupuncture needle to obliquely and longitudinally penetrate the ventral part of triceps of the lower leg along its lateral side, followed by retaining the needle for 2 min. Changes of the collagen fibers in each group was observed by scanning electron microscope. The expressions of Collagen Ⅰ, TGF-ß1, phosphated (p)-ERK/ERK and CTGF proteins were detected by Western blot. RESULTS: After 3 weeks of eccentric exercise and acupuncture, the fibrosis and deposition of collagen fibers in the exercise group were significantly higher than that in the normal control group,the degree of fibrosis in the acupuncture group was significantly lower than that in the exercise group. Compared with the normal control group, the expression levels of Collagen Ⅰ, TGF-ß1, CTGF and p-ERK/ERK in the exercise group was significantly higher (P<0.01，P<0.05). After EA interventions, the increased levels of the above indicators were significantly reversed (P<0.05，P<0.01) apart from p-ERK/ERK which had a downward trend, but the difference was not statistically significant. CONCLUSION: The accumulation of chronic sports injury can lead to the deposition of collagen fibers in skeletal muscle, which leads to the fibrosis of skeletal muscle. Acupuncture can inhibit skeletal muscle fibrosis via down-regulating TGF-ß1/ERK/CTGF signaling pathway.

[Changes of dystrophin and desmin in rat gastrocnemius under micro-damage induced by hypoxia].

To explore the changes and regulation mechanism of dystropin and desmin under muscle injury without mechanic stress, 40 male Sprague-Dawley rats were randomly divided into 5 groups, which included normoxia control and hypoxia groups for 1, 2, 4 and 7 d with 10% O2. Two rats from each group were examined for sarcolemma integrity using Evans blue dye (EBD) and EBD-positive fiber typing by metachromatic dye-ATPase method. The rest six rats from each group were analyzed for the changes of protein content and gene expression using Western blot, RT-PCR and fluorescence assays. The results showed that the EBD-positive muscle fibers, mainly type IIA and type IIB, appeared at 1 d after hypoxia exposure. Both the ratio of EBD-positive cell and the mean fluorescence density were significantly higher in hypoxia groups than those in control group (P<0.05). The contents of dystrophin and desmin fluctuated after hypoxia exposure, increased at 1 d, decreased at 2 d, increased dramatically again at 4 d, and returned to a normal level at 7 d. Consistently, the gene expression began to increase significantly after 2 d. The total activity of calpain was significantly higher in hypoxia groups at 1, 4 and 7 d. Significantly higher levels of HSP70 and HSP90 were also observed at 4 and 7 d, respectively (P<0.05). These results suggest that the mechanical stress is not the only cause of damage of sarcolemma membrane integrity. In contrast to eccentric contraction, hypoxia-induced muscle damage is not accompanied by the loss of dystrophin and desmin. The types of muscle fibers recruited by motor units and the activities of calpain may be important in hypoxia-induced damage of sarcolemma membrane integrity.

[Effects of high-load exercise induced skeletal muscle injury on autophagy ultrastructure and Beclin1 and LC3-II / I in rats].

OBJECTIVE: To investigate the effects of high-load eccentric exercise on the ultrastructure of autophagy and the autophagy-related proteins Beclin1 and LC3II / I in rats. METHODS: Forty-eight SD male rats were randomly divided into control group (C, n=8) and high-load eccentric exercise group (E, n=40) after adaptive training. Group E was run downhill for 90 minutes on the running platform, and soleus muscles were collected at 0, 12, 24, 48 and 72 hours after exercise. Transmission electron microscopy was used to observe the ultrastructural changes of skeletal muscle autophagosomes. Western blot was used to detect the expressions of Beclin1 and LC3II / I protein. Immunofluorescence was used to observe the localization and content of LC3. RESULTS: The number of soleus muscle autophagosomes in group E was increased at 0, 12 and 24 hours after exercise, and LC3 autophagic fluorescence was significantly increased (P＜0.01), while autophagic fluorescence at 48 hours after exercise was still increased significantly (P＜0.05). Beclin1 and LC3II / I expression levels were increased after high-load centrifugal intervention (P＜0.05), and were peaked at 12 h～24 h after exercise (P＜0.01), and fully recovered at 72 h after exercise. CONCLUSION: High-load eccentric exercise can induce ultrastructural changes in skeletal muscle autophagy and increase the expression of autophagy protein. The peak value appears at 12 hours after exercise. The above may be one of the reasons for the decline in skeletal muscle function caused by sports injury.

Influence of short- and long-term treadmill exercises on levels of ghrelin, obestatin and NPY in plasma and brain extraction of obese rats.

This study aims to clarify the effects of exercise on levels of appetite regulatory hormones in plasma and hypothalamus of obese rats. Diet-induced obese rats undergo short- (40 min) and long-term (40 min, 5 days/week for 8 weeks) exercises. The rats ran at a speed of 20 m/min on a 5 degrees slope treadmill. Rats undergoing short-term exercise were divided into C, E0, E1, E3, E12, and E24. Rats undergoing long-term exercise (LE) were compared to long-term control (LC). Concentrations of ghrelin, obestatin, and neuropeptide Y (NPY) were measured using radio immuno-assay. Expression of ghrelin receptor (GHSR-1a), putative obestatin receptor (GPR-39), and NPY in the hypothalamus was measured by quantitative RT-PCR. After short-term exercise, the plasma concentrations of ghrelin and obestatin were not changed, but NPY decreased. Ghrelin and obestatin in the hypothalamus decreased, and recovered 12 until 24 h. NPY increased and recovered after 24 h. Expression of GHSR-1a and NPY was not changed and GPR-39 was not observed. In LE, these changes are different in plasma and hypothalamus. It would be concluded appetite and body weight of obese rats are decreased by exercise through reduced level of ghrelin in the hypothalamus. Obestatin seems to have no effect in exercise-induced change in appetite.

[Developing a straight wire bracket placement gauge].

OBJECTIVE: To develop a new straight wire bracket placement gauge, providing measurement instrument for it's accurate position. Methods The gauge was made of 3.0 mm x 6.0 mm stainless steel, after being curved in certain form, made by machine process and cleaned through removing tough and polishing. The bracket placement gauge is divided into three parts: the middle straight stem, the curve head and the measurement head. It was 146 mm long, the angle between straight stem and curve was 145 degrees,the angle between the curve and measurement head was 105 degrees.The measurement head was made of occlusion placement item and slot placement item. The occlusion placement item was 10 mm long and 2 mm thick. The slot placement item was 2 mm long and 0.4 mm thick. This suit of gauge had 7 pieces, the measurement scope was 2.5 mm-5.5 mm which reflected the different vertical distances from occlusion edge to the middle point of slot. RESULTS: This gauge can determine the vertical position of bracket. CONCLUSION: The gauge improve the accuracy with individual straight wire bracket position table.