Skeletal Muscle Tissue Samples Research Articles

Efeitos da atividade física na histomorfometria muscular esquelética de modelo tumoral murino de caquexia

INTRODUÇÃO: A caquexia associada ao câncer (CAC) é uma síndrome paraneoplásica que ocorre com indivíduos com câncer que é caracterizada pela diminuição gradual de tecidos muscular esquelética e de tecido adiposo, promovendo um quadro de consumação física do indivíduo. A ocorrência de CAC determina de forma significativa a uma pior qualidade de vida e de sobrevida de indivíduos com câncer. A CAC não pode ser revertida pelo amparo nutricional convencional. Tratamentos não-farmacológicos empregados para a CAC tem reportado a realização de atividade física para possibilitar adaptações neurais e de hipertrofia muscular em indivíduos com a síndrome. OBJETIVO: Verificar os efeitos da atividade física em ambiente enriquecido na histomorfometria da musculatura esquelética de camundongos C57BL/6 submetidos ao modelo tumoral murino de caquexia associada ao câncer (CAC) MÉTODOS: Foram utilizados 38 camundongos C57BL/6 fêmeas, distribuídos aleatoriamente nos grupos de estudo. Todos os animais foram submetidos ao modelo tumoral murino singênico de Melanoma Cutâneo (MTMSMC) com a inoculação subcutânea de células B16F10. Os grupos de estudo são animais do experimento diagnostico CRC (n = 12), animais sedentários (n = 11) e animais submetidos à prática de atividade física em ambiente enriquecido (n = 15). O seguimento do estudo ocorreu por um período de dez dias. Após esse momento, todos os animais foram sacrificados e amostras de tecido muscular esquelético do gastrocnêmio foram submetidas às análises histomorfométricas. RESULTADOS: Os resultados da análise inferencial do peso absoluto e relativo muscular esquelético não diferiram entre os grupos do estudo. Todas as comparações das variáveis apresentaram tamanho do efeito pequeno. A análise histomorfométrica muscular revelou que a área da fibra muscular não diferiu entre os grupos do estudo. Contudo, essa área muscular, apresentou tamanho do efeito pequeno. CONCLUSÃO: Os resultados apresentados mostraram que a realização de atividade física no ambiente enriquecido não influenciou na área da fibra do músculo do gastrocnêmio de camundongos C57BL/6 submetidos ao MTMSMC, associada à CAC.

PSXI-34 Supplementation of grazing Nellore beef heifers during mid-to-late gestation as a strategy to improve skeletal muscle development of the offspring

Abstract The aim of this study was to evaluate supplementation effects of grazing heifers during mid-to-late of gestation on skeletal muscle development and performance of the progeny until weaning. One hundred and eighty Nellore beef heifers confirmed pregnant (timed AI) to a single sire were allotted to a completely randomized design with 2 treatments. Ninety heifers were fed only mineral (control) and the other 90 were fed a protein supplement (44.5% CP, 0.15% BW) from 90 to 274 days of gestation. Cows were grazed on Urochloa brizantha cv. Marandu pastures (5% CP and 64% NDF). At calving, cow–calf pairs were commingled and grazed on the same pasture until weaning. At 30 days after birth, a biopsy was performed to obtain samples of skeletal muscle tissue (Semitendinosus) from calves to determine the number and size of muscle fibre. Least squares mean for all data were computed using PROC MIXED of SAS (SAS Inst. Inc., Cary, NC). Calves from heifers supplemented with protein had greater birth BW (P < 0.001), ADG (P = 0.0147) and BW at 155 d (P = 0.0016) compared with calves from heifers not supplemented. However, calf BW at weaning (P = 0.1508) and gain from birth to weaning (P = 0.1446) did not differ. On the other hand, calves born from dams supplemented with protein had greater muscle fibre number (P = 0.0262), larger diameter of the fiber (P < 0.001), and smaller diameter of the fiber (P < 0.001) compared with calves from heifers not supplemented, although did not differ for mean fiber diameter (P = 0.8079). Fiber volume, fiber perimeter, and volume/area ratio were also affected (P < 0.001) by prepartum supplementation, and were greater on calves whose dams were fed with protein. In conclusion, supplementation of pregnant Nellore heifers with protein during the dry season improves calf birth BW, and promotes hyperplasia and hypertrophy in the skeletal muscle of the offspring.

Protein supplementation elicits greater gains in maximal oxygen uptake capacity and stimulates lean mass accretion during prolonged endurance training: a double-blind randomized controlled trial

Endurance training induces numerous cardiovascular and skeletal muscle adaptations, thereby increasing maximal oxygen uptake capacity (VO2max). Whether protein supplementation enhances these adaptations remains unclear. The present study was designed to determine the impact of protein supplementation on changes in VO2max during prolonged endurance training. We used a double-blind randomized controlled trial with repeated measures among 44 recreationally active, young males. Subjects performed 3 endurance training sessions per week for 10 wk. Supplements were provided immediately after each exercise session and daily before sleep, providing either protein (PRO group; n=19; 21.5±0.4 y) or an isocaloric amount of carbohydrate as control (CON group; n=21; 22.5±0.5 y). The VO2max, simulated 10-km time trial performance, and body composition (dual-energy X-ray absorptiometry) were measured before and after 5 and 10 wk of endurance training. Fasting skeletal muscle tissue samples were taken before and after 5 and 10 wk to measure skeletal muscle oxidative capacity, and fasting blood samples were taken every 2 wk to measure hematological factors. VO2max increased to a greater extent in the PRO group than in the CON group after 5 wk (from 49.9±0.8 to 54.9±1.1 vs 50.8±0.9 to 53.0±1.1 mL · kg-1 · min-1; P<0.05) and 10 wk (from 49.9±0.8 to 55.4±0.9 vs 50.8±0.9 to 53.9±1.2 mL · kg-1 · min-1; P<0.05). Lean body mass increased in the PRO group whereas lean body mass in the CON group remained stable during the first 5 wk (1.5±0.2 vs 0.1±0.3 kg; P<0.05) and after 10 wk (1.5±0.3 vs 0.4±0.3 kg; P<0.05). Throughout the intervention, fat mass reduced significantly in the PRO group and there were no changes in the CON group after 5 wk (-0.6±0.2 vs -0.1±0.2 kg; P>0.05) and 10 wk (-1.2±0.4 vs -0.2±0.2 kg; P<0.05). Protein supplementation elicited greater gains in VO2max and stimulated lean mass accretion but did not improve skeletal muscle oxidative capacity and endurance performance during 10 wk of endurance training in healthy, young males. This trial was registered at clinicaltrials.gov as NCT03462381.

Skeletal-muscle-derived mesenchymal stem/stromal cells from patients with osteoarthritis show superior biological properties compared to bone-derived cells

Mesenchymal stem/stromal cells (MSCs) are being exploited for patient-derived stem-cell therapies. As the biological properties of MSCs derived from skeletal muscle of osteoarthritis patients are poorly understood, the aim of this study was to compare muscle MSCs with well-recognized bone and bone marrow-derived MSCs from these patients.Paired samples of skeletal muscle and trabecular bone tissue were obtained from 21 patients with osteoarthritis. Isolated cells were compared using ex vivo immunophenotyping and detailed in vitro analyses. These included the colony forming unit fibroblast assay, growth kinetics, senescence, multilineage potential, immunophenotyping, and MSC marker gene expression profiling.Freshly isolated MSCs from muscle showed improved viability over bone-derived MSCs, with similar mesenchymal fraction. Muscle-derived MSCs showed superior clonogenicity, higher growth rates, and lower doubling times. Muscle-derived MSCs also showed superior osteogenic and myogenic properties and a positive correlation between CD271 expression and adipogenesis. Senescence rate as well as adipogenic and chondrogenic potentials were similar.Skeletal muscle-derived MSCs of osteoarthritis patients have superior clonogenicity and growth kinetics compared to bone-derived MSCs, making them a good candidate for autologous stem-cell therapies. Moreover, the positive correlation between CD271 and adipogenesis suggest that CD271 expressing muscle MSCs might contribute to muscle steatosis observed in osteoarthritis.

How sleep loss leads to weight gain

Physiology Chronic sleep loss can have negative health effects, including weight gain and type 2 diabetes. Underlying molecular processes in key metabolic tissues are thought to be to blame. Cedernaes et al. compared molecular changes such as DNA methylation in fat and skeletal muscle tissue samples taken from 15 young Caucasian males after a night of sleep loss and after a normal night's sleep. The two tissue types responded very differently. In muscle, sleep loss enhanced skeletal muscle breakdown by down-regulating a metabolic pathway. However, the same pathway was up-regulated in fat tissue after disrupted sleep. Thus, sleep loss may reprogram fat tissue to increase fat storage. Sci. Adv. 10.1126/sciadv.aar8590 (2018).

Assessment of Skeletal Muscle Nicotinamide Adenine Dinucleotide Concentrations in Rat Strains Exhibiting Different Levels of Play Behavior

Relative to Sprague‐Dawley (SD) and Lewis (LEW) rats, the Fischer 344 (F344) strain displays reduced play behavior. While neurobiological explanations for these behavioral differences have been explored, we investigated whether impaired skeletal muscle mitochondrial function may contribute to these observed variations.Nicotinamide adenine dinucleotide (NAD) is an important cofactor in protein deacetylase reactions regulating mitochondrial content and activity. We hypothesized that there would be strain‐dependent differences in skeletal muscle NAD concentrations ([NAD]) matching differing levels of play behavior in these strains. We also hypothesized that F344 rats would show reduced protein expression of nicotinamide phosphoribosyl transferase (Nampt), a key enzyme in intracellular NAD recycling, and sirtuin 3 (SIRT3), an NAD‐dependent protein deacetylase governing mitochondrial content and function.Rat soleus muscles were obtained from anesthetized SD (n = 10), LEW (n = 7), and F344 (n = 7) rats and processed for NAD measurements. Skeletal muscle tissue samples were homogenized in perchloric acid. Intracellular NAD was quantified via HPLC elution and UV‐visible spectroscopy detection at 261 nm. NAD quantification via HPLC was validated through the analysis of NAD standards and spike‐recovery samples. Tissue harvesting and processing methods for HPLC analysis were optimized to account for the effects of tissue hypoxia, sample storage temperature, and the number of freeze‐thaw cycles on [NAD]. In addition, relative amounts of Nampt and SIRT3 protein expression were determined via immunoblots.NAD could be detected reliably and reproducibly by HPLC. Tissues exposed to hypoxic conditions during dissection and collection showed sensitivity to NAD degradation relative to controls. Sample [NAD] were stable at or below 4°C for at least 1 week.Average NAD concentrations were not statistically significantly different between the three rat strains (SD, 13.2 ± 0.89 [mean ± S.E.M] μM/mg tissue, LEW, 14.4 ± 0.81 μM/mg, F344, 13.9 ± 1.21 μM/mg; p = 0.66). No significant difference in Nampt expression was found between the three strains (p = 0.56). However, SIRT3 expression differed statistically significantly between the three strains (SD 0.97 ± 0.076 arbitrary units (AU), LEW 1.26 ± 0.085 AU, F344 1.72 ± 0.187 AU; p = 0.0006). Post‐hoc testing revealed that SIRT3 expression was significantly lower in SD (p &lt; 0.01) and LEW (p &lt; 0.05) strains compared to F344 rats. There was no statistically significant difference in SIRT3 expression between the SD and LEW strains (p = 0.50). No significant correlations between skeletal muscle [NAD], Nampt expression, or SIRT3 expression were detected.In conclusion, F344 rats exhibiting reduced playfulness are characterized by a marked increase in skeletal muscle SIRT3 protein expression despite unaltered intracellular NAD compared to both SD and LEW rats. While intracellular [NAD] are stable between strains, different NAD/SIRT3 ratios suggest altered dynamics of NAD‐dependent mitochondrial protein deacetylases.Support or Funding InformationThis work was supported in part by a grant to Gettysburg College from the Howard Hughes Medical Institute through the Precollege and Undergraduate Science Education Program, and by Gettysburg College.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Skeletal muscle insulin signaling and whole-body glucose metabolism following acute sleep restriction in healthy males.

Sleep restriction is associated with impaired glucose metabolism and insulin resistance, however, the underlying mechanisms leading to this impairment are unknown. This study aimed to assess whether the decrease in insulin sensitivity observed after sleep restriction is accompanied by changes in skeletal muscle PKB activity. Ten healthy young males participated in this randomized crossover study which included two conditions separated by a 3‐week washout period. Participants underwent two nights of habitual sleep (CON) and two nights of sleep which was restricted to 50% of habitual sleep duration (SR) in the home environment. Whole‐body glucose tolerance and insulin sensitivity were assessed by an oral glucose tolerance test after the second night of each condition. Skeletal muscle tissue samples were obtained from the vastus lateralis to determine PKB activity. Findings displayed no effect of trial on plasma glucose concentrations (P = 0.222). Plasma insulin area under the curve was higher after sleep restriction compared to the control (P = 0.013). Matsuda index was 18.6% lower in the sleep restriction (P = 0.010). Fold change in PKB activity from baseline tended to be lower in the sleep restriction condition at 30 min (P = 0.098) and 120 min (P = 0.087). In conclusion, we demonstrated decreased whole‐body insulin sensitivity in healthy young males following two nights of sleep restriction. Skeletal muscle insulin signaling findings are inconclusive and require further study to examine any potential changes.

Cyclooxygenase 2 contributes to bradykinin-induced microvascular responses in peripheral arterioles after cardiopulmonary bypass

BackgroundDiabetic patients are associated with impaired peripheral microvascular function after cardiopulmonary bypass (CPB) and cardiac surgery. We hypothesized that upregulation of the inducible cyclooxygenase 2 (COX-2) contributes to altered microvascular reactivity of peripheral arterioles in diabetic patients undergoing CPB and cardiac surgery. MethodsSkeletal muscle samples of nondiabetic (ND) patients and patients with diabetes mellitus (DM; n = 8 per group) undergoing cardiac surgery were harvested before and after CPB. The protein expression/localization of COX-2 was assayed by Western blotting and immunohistochemistry. Peripheral arterioles were dissected from the harvested skeletal muscle tissue samples, the isolated arterioles (80-180 μm) were cannulated and pressurized, and changes in diameter were measured with video microscopy. In-vitro relaxation responses of precontracted arterioles were examined in the presence of the endothelium-dependent vasodilator bradykinin (10−10 to 10−6M) and in the presence or absence of the selective COX-2 inhibitor NS398 (10−5M). ResultsThe post-CPB protein levels of the inducible COX-2 were significantly increased compared with pre-CPB values in both the ND and DM groups (P < 0.05), whereas, this increase was higher in DM than that of ND (P < 0.05). In the DM arterioles, not the ND vessels, bradykinin-induced relaxation response was inhibited in the presence of the specific COX-2 inhibitor NS398 at baseline (P < 0.05). After CPB, bradykinin-induced relaxation response of the ND and DM arterioles was inhibited in the presence of the specific COX-2 inhibitor NS398, but this effect was more pronounced in the diabetic patients (P < 0.05). ConclusionsDiabetes and CPB are associated with upregulation in COX-2 expression/activation in human peripheral microvasculature. This alteration may lead to altered peripheral microvascular reactivity in diabetic patients undergoing cardiac surgery.

Supplementation of grazing beef cows during gestation as a strategy to improve skeletal muscle development of the offspring

The appropriate supply of nutrients in pregnant cows has been associated with the optimal development of foetal tissues, performance of their progeny and their meat quality. The aim of this study was to evaluate supplementation effects of grazing cows in different stages of gestation on skeletal muscle development and performance of the progeny. Thereby, 27 Nellore cows were divided into three groups (n=9 for each group) and their progeny as follows: UNS, unsupplemented during gestation; MID, supplemented from 30 to 180 days of gestation; LATE, supplemented from 181 to 281 days of gestation. The percentage composition of the supplement provided for the matrices was the following: ground corn (26.25%), wheat bran (26.25%) and soya bean meal (47.5%). The supplement was formulated to contain 30% CP. Supplemented matrices received 150 kg of supplement (1 and 1.5 kg/day for cows in the MID and LATE groups, respectively). After birth, a biopsy was performed to obtain samples of skeletal muscle tissue from calves to determine number and size of muscle fibres and for messenger RNA (mRNA) expression analysis. The percentage composition of the supplement provided for the progeny was the following: ground corn grain (30%), wheat bran (30%), soya bean meal (35%) and molasses (5%). The supplement was formulated to contain 25% CP and offered in an amount of 6 g/kg BW. Performance of the progeny was monitored throughout the suckling period. Means were submitted to ANOVA and regression, and UNS, MID and LATE periods of supplementation were compared. Differences were considered at P<0.10. Birth weight, average daily gain and weaning weight of the offspring did not differ among treatments (P>0.10). Similarly, no differences were observed between calves for nutrient intake (P>0.10). However, greater subcutaneous fat thickness (P=0.006) was observed in the calves of LATE group. The ribeye area (P=0.077) was greater in calves born from supplemented compared with UNS cows. The supplementation of pregnant cows did not affect the muscle fibre size of their progeny (P=0.208). On the other hand, calves born from dams supplemented at mid-gestation had greater muscle fibre number (P=0.093) compared with calves from UNS group. Greater mRNA expression of peroxysome proliferator-activated receptor α (P=0.073) and fibroblast growth factor 2 (P=0.003) was observed in the calves born from MID cows. Although strategic supplementation did not affect the BW of offspring, it did cause changes in carcass traits, number of myofibres, and mRNA expression of a muscle hypertrophy and lipid oxidation markers in skeletal muscle of the offspring.

Effects of diabetes and cardiopulmonary bypass on expression of adherens junction proteins in human peripheral tissue

We investigated the changes in adherens junction proteins, such as vascular endothelial-cadherin and β-catenin, of skeletal muscle and vessels in patients with or without diabetes in the setting of cardiopulmonary bypass and cardiac operation. Skeletal muscle tissue samples were harvested pre- and post-cardiopulmonary bypass from nondiabetic (hemoglobin A1c: 5.4±0.1), controlled diabetic (hemoglobin A1c: 6.3±0.1), and uncontrolled diabetic patients (hemoglobin A1c: 9.6±0.3) undergoing coronary artery bypass grafting operation (n=8 per group). The expression/phosphorylation of adherens junction proteins vascular endothelial-cadherin and β-catenin were assessed by immunoblotting and immuno-histochemistry. Endothelial function of skeletal muscle arterioles was determined by videomicroscopy in response to the vasodilator substance P. The protein expression of total vascular endothelial-cadherin was not changed at baseline or between pre-and post-cardiopulmonary bypass among groups. The pre-cardiopulmonary bypass level of phospho-vascular endothelial-cadherin was found to be significantly increased in the uncontrolled diabetic patients group compared with the nondiabetic or controlled diabetic groups (P<.05). The post-cardiopulmonary bypass levels of phospho-vascular endothelial-cadherin were significantly increased compared with pre-cardiopulmonary bypass in all groups (P<.05 each), and this increase was greater in the uncontrolled diabetic patients group than that of the nondiabetic or controlled diabetic groups (P<.05). Expression of basal β-catenin protein in the uncontrolled diabetic group was decreased compared with nondiabetic or controlled diabetic groups (P<.05). There were significant decreases in the β-catenin protein expression between pre- and post-cardiopulmonary bypass in all 3 groups (P<.05 each), and this decrease was greater in the uncontrolled diabetic patients group than the nondiabetic group (P<.05). There were decreases in the relaxation response of skeletal muscle arterioles to substance P after cardiopulmonary bypass in all 3 groups (P<.05), and this alteration was more pronounced in the uncontrolled diabetic patients (P<.05). Uncontrolled diabetes causes inactivation and reduction in the expression of endothelial adherens junction proteins in the arterioles of skeletal muscle early after cardiopulmonary bypass. The enhanced phosphorylation of vascular endothelial-cadherin and degradation of β-catenin indicate deterioration of these proteins and damage of the cell-cell endothelial junctions, specifically in the diabetic peripheral vessels. These alterations may contribute to the increases in peripheral vascular permeability and endothelial dysfunction.

Metformin Effect on Nontargeted Metabolite Profiles in Patients With Type 2 Diabetes and in Multiple Murine Tissues

Metformin is the first-line oral medication to increase insulin sensitivity in patients with type 2 diabetes (T2D). Our aim was to investigate the pleiotropic effect of metformin using a nontargeted metabolomics approach. We analyzed 353 metabolites in fasting serum samples of the population-based human KORA (Cooperative Health Research in the Region of Augsburg) follow-up survey 4 cohort. To compare T2D patients treated with metformin (mt-T2D, n = 74) and those without antidiabetes medication (ndt-T2D, n = 115), we used multivariable linear regression models in a cross-sectional study. We applied a generalized estimating equation to confirm the initial findings in longitudinal samples of 683 KORA participants. In a translational approach, we used murine plasma, liver, skeletal muscle, and epididymal adipose tissue samples from metformin-treated db/db mice to further corroborate our findings from the human study. We identified two metabolites significantly (P < 1.42E-04) associated with metformin treatment. Citrulline showed lower relative concentrations and an unknown metabolite X-21365 showed higher relative concentrations in human serum when comparing mt-T2D with ndt-T2D. Citrulline was confirmed to be significantly (P < 2.96E-04) decreased at 7-year follow-up in patients who started metformin treatment. In mice, we validated significantly (P < 4.52E-07) lower citrulline values in plasma, skeletal muscle, and adipose tissue of metformin-treated animals but not in their liver. The lowered values of citrulline we observed by using a nontargeted approach most likely resulted from the pleiotropic effect of metformin on the interlocked urea and nitric oxide cycle. The translational data derived from multiple murine tissues corroborated and complemented the findings from the human cohort.

A murine model of peripheral irradiation-induced fatigue

PurposeFatigue is the most ubiquitous side effect of cancer treatment, but its etiology remains elusive. Further investigations into cancer-related fatigue pathobiology necessitate the expanded use of animal models. This study describes the development of a murine model of radiation-induced fatigue. MethodsVoluntary wheel running activity measured fatigue in 5–8 week-old, male C57BL/6 mice before and after γ irradiation totaling 2400cGy (3 consecutive days×800cGy daily fractionated doses) to the lower abdominal areas. Three trials confirmed fatigue behavior at this dose. Anhedonia, body weight, and hemoglobin were also measured. Gastrointestinal, skeletal muscle, and bone marrow tissue samples were evaluated for signs of damage. ResultsIn two validation trials, irradiated mice (trial 1, n=8; trial 2, n=8) covered less cumulative distance in kilometers post-irradiation (trial 1, mean=115.3±12.3; trial 2, mean=113.6±21.8) than sham controls (trial 1, n=5, mean=126.3±5.7, p=0.05; trial 2, n=8, mean=140.9±25.4, p=0.02). Decreased mean daily running distance and speed were observed during the last four hours of the dark cycle in irradiated mice compared to controls for two weeks post-irradiation. There were no differences in saccharin preference or hemoglobin levels between groups, no effect of changes in body weight or hemoglobin on wheel running distance, additionally, histology showed no damage to muscle, bone marrow, or gastrointestinal integrity, with the latter confirmed by ELISA. ConclusionWe characterized a novel mouse model of fatigue caused by peripheral radiation and not associated with anemia, weight changes, or anhedonia. This model provides opportunities for detailed study of the mechanisms of radiation-induced fatigue.

Effects of ischemic preconditioning protocols on skeletal muscle ischemia–reperfusion injury

BackgroundIschemic preconditioning (IPC) is described as brief ischemia–reperfusion (I/R) cycles to induce tolerance to subsequent in response to longer I/R insults. Various IPC protocols can be performed in four combinations as follows: at early or late phases and on local or distant organs. Although many experimental studies have been performed on IPC, no consensus has been established on which IPC protocol is most effective. The aims of the present study were as follows: (1) to compare the variables of preconditioning in different combinations (in early versus late phases; local versus remote organ implementations) and (2) to determine the most therapeutic IPC protocol(s). Materials and methodsA subtotal hind limb amputation model with clamping an intact femoral pedicle was used for I/R injury. IPC was induced using hind limb tourniquet with 3 × 10 min I/R cycles before longer I/R insult. Forty-nine rats were divided into seven groups (n = 7), sham, IsO (ischemia only), I/R, early ischemic preconditioning (e-IPC), late ischemic preconditioning (l-IPC), early remote ischemic preconditioning (e-RIPC), and l-RIPC (late-remote) groups, respectively. In the sham group, pedicle occlusion was not performed. Six hours ischemia was challenged in the IsO group. Three hours ischemia followed by 3 h reperfusion was performed in the I/R group. The e-IPC group was immediately preconditioned, whereas the l-IPC group was preconditioned 24 h before I/R injury on the same hind limb. In the e-RIPC and l-RIPC groups, the same protocols were performed on the contralateral hind limb. At the end of the experiments, skeletal muscle tissue samples were obtained for biochemical analysis (Malondialdehyde [MDA], catalase, myeloperoxidase [MPO], and nitric oxide end products [NOx]), light microscopy, and caspase-3 immunohistochemistry for determination of apoptosis. ResultsTissue biochemical markers were improved in nearly all the IPC groups compared with IsO and I/R groups (P < 0.05). Similarly, the histologic damage scores were decreased in all the IPC groups (P < 0.05). The lowest damage score was in the e-RIPC group followed by the l-RIPC, e-IPC, and l-IPC groups, respectively. The apoptosis scores were significantly high in the I/R group compared with the e-RIPC and l-RIPC groups (P < 0.05). Although apoptosis scores of the e-IPC and l-IPC groups were lower than the I/R group, this finding was not statistically significant (P > 0.05). ConclusionsAll IPC protocols were effective in reducing I/R injury. Among these protocols, e-RIPC achieved most protection.

Human skeletal muscle biopsy procedures using the modified Bergström technique.

The percutaneous biopsy technique enables researchers and clinicians to collect skeletal muscle tissue samples. The technique is safe and highly effective. This video describes the percutaneous biopsy technique using a modified Bergström needle to obtain skeletal muscle tissue samples from the vastus lateralis of human subjects. The Bergström needle consists of an outer cannula with a small opening ('window') at the side of the tip and an inner trocar with a cutting blade at the distal end. Under local anesthesia and aseptic conditions, the needle is advanced into the skeletal muscle through an incision in the skin, subcutaneous tissue, and fascia. Next, suction is applied to the inner trocar, the outer trocar is pulled back, skeletal muscle tissue is drawn into the window of the outer cannula by the suction, and the inner trocar is rapidly closed, thus cutting or clipping the skeletal muscle tissue sample. The needle is rotated 90°and another cut is made. This process may be repeated three more times. This multiple cutting technique typically produces a sample of 100-200 mg or more in healthy subjects and can be done immediately before, during, and after a bout of exercise or other intervention. Following post-biopsy dressing of the incision site, subjects typically resume their activities of daily living right away and can fully participate in vigorous physical activity within 48-72 hr. Subjects should avoid heavy resistance exercise for 48 hr to reduce the risk of herniation of the muscle through the incision in the fascia.

Adverse effects of aflatoxin B1 on skeletal muscle development in broiler chickens

1. Detrimental effects of in ovo administrated of aflatoxin B1 (AFB1) on the embryonic development of skeletal muscle were determined using histological methods.2. A total of 420 eggs of a Ross broiler parent stock were incubated and divided into 4 groups: (1) control, (2) 5 ng AFB1/egg group, (3) 15 ng AFB1/egg group, (4) 40 ng AFB1/egg group. Test solutions were injected via the air-sac, just prior to setting the eggs in the incubator.3. Five eggs from each group were opened on different days of incubation (11d, 13d, 17d and 21d). Developmental stages of embryos were determined according to the Hamburger–Hamilton scale and embryos were weighed. Skeletal muscle tissue samples were dissected and fixed, sectioned and stained with Crossman’s trichrome and AgNOR.4. The mean relative embryo, leg muscle and breast muscle weights of AFB1-treated groups were lower than the control group and decreased with increasing AFB1. The nucleus area and AgNOR area of the AFB1-treated groups were also lower than the control group whereas there were no significant differences in AgNOR numbers and AgNOR area/nucleus area among the treatment groups.5. It was concluded that in ovo administrated of AFB1 adversely affected the embryonic development of skeletal muscle and that affected animals might therefore be more susceptible to skeletal and muscle disorders during the growing period.

Differential expression of miRNAs with metabolic implications in hibernating thirteen-lined ground squirrels, Ictidomys tridecemlineatus.

Mammalian hibernators undergo significant physiological and biochemical changes when confronted with cold temperatures. Metabolic depression and translational repression are two examples of the various processes impacted during a torpor bout. MicroRNAs (miRNAs), non-coding transcripts that bind to mRNAs, are known regulators of mRNA translation and a growing number of these molecules have been found to be differentially expressed during hibernation. We hypothesized that a group of six miRNAs, with targets involved in various metabolic cascades, is modulated in selected tissues of the hibernating thirteen-lined ground squirrel Ictidomys tridecemlineatus. Expression levels of these miRNAs were assessed in the liver, heart, and skeletal muscle ground squirrel tissues using qRT-PCR. miR-29a, miR-152, miR-195, miR-223, and miR-486 were shown to be up-regulated in the hibernating liver, while miR-378 was shown to be down-regulated in hibernating skeletal muscle tissue samples. Interestingly, fatty acid synthase (FAS), an enzyme involved in fatty acid biosynthesis and a miR-195 target, was shown to be down-regulated in hibernating squirrel liver. This data add to the growing signature of differentially expressed miRNAs during hibernation and puts the light on the potential regulation of fatty acid homeostasis by a miRNA in torpid animals.

Effects of obesity, diabetes and exercise on Fndc5 gene expression and irisin release in human skeletal muscle and adipose tissue: in vivo and in vitro studies

Irisin was identified as a myokine secreted by contracting skeletal muscle, possibly mediating some exercise health benefits via 'browning' of white adipose tissue. However, a controversy exists concerning irisin origin, regulation and function in humans. Thus, we have explored Fndc5 gene and irisin protein in two clinical studies: (i) a cross-sectional study (effects of type 2 diabetes (T2D) in drug-naive men) and (ii) an intervention study (exercise effects in sedentary, overweight/obese individuals). Glucose tolerance and insulin sensitivity were assessed. Maximal aerobic capacity and muscle strength were measured before and after training. Body composition (magnetic resonance imaging), muscle and liver fat content (1H-magnetic resonance spectroscopy (MRS)) and in vivo muscle metabolism (32P-MRS) were determined. Skeletal muscle and subcutaneous abdominal adipose tissue samples were taken in the fasted state and during euglycaemic hyperinsulinaemia (adipose tissue) and before/after exercise training (muscle). We found that muscle Fndc5 mRNA was increased in prediabetes but not T2D. Fndc5 in adipose tissue and irisin in plasma were reduced in T2D by 40% and 50%, respectively. In contrast, T2D-derived myotubes expressed/secreted the highest levels of Fndc5/irisin. Neither hyperinsulinaemia (adipose tissue/plasma) nor exercise (muscle/plasma) affected Fndc5/irisin in vivo. Circulating irisin was positively associated with muscle mass, strength and metabolism and negatively with fasting glycaemia. Glucose and palmitate decreased Fndc5 mRNA in myotubes in vitro. We conclude that distinct patterns of Fndc5/irisin in muscle, adipose tissue and circulation, and concordant in vivo down-regulation in T2D, indicate that irisin might distinguish metabolic health and disease. Moreover, Fndc5/irisin was discordantly regulated in diabetic muscle and myotubes in vitro, suggesting that whole body factors, such as glucose and fatty acids, might be important for irisin regulation. Exercise did not affect Fndc5/irisin. However, irisin was positively linked to muscle mass, strength and metabolism, pointing to common regulatory factors and/or the potential for irisin to modify muscle phenotype.

Two-dimensional and surface backscattering Mueller matrices of anisotropic sphere-cylinder scattering media: a quantitative study of influence from fibrous scatterers

We present both the two-dimensional backscattering point-illumination and surface-illumination Mueller matrices for the anisotropic sphere-cylinder scattering media. The experimental results of the microsphere-silk sample show that the Mueller matrix elements of an anisotropic scattering medium are different from those of an isotropic medium. Moreover, both the experiments and Monte Carlo simulations show that the directions of the fibrous scatterers have prominent effects on the Mueller matrix elements. As the fibrous samples rotate, the surface-illumination Mueller matrix measurement results for the m12, m21, m13, m31, m22, m23, m32, and m33 elements represent periodical variations. Experiments on skeletal muscle and porcine liver tissue samples confirm that the periodical changes for the surface-illumination Mueller matrix elements are closely related to the well aligned fibrous scatterers. The m22, m23, m32, and m33 elements are powerful tools for quantitative characterization of anisotropic scattering media, including biological tissues.

Oxytocin Protects Rat Skeletal Muscle Against Ischemia/Reperfusion Injury

Oxytocin (OXY) is a well-known nonapeptide that functions in reproduction. It is also known as an antioxidant in several organs. However, little is about its role in the protection of tissue against ischemia/reperfusion injury in skeletal muscle. The aim of this study was to evaluate the protective and therapeutic antioxidant effect of oxytocin in skeletal muscle during ischemia/reperfusion (I/R) injury. Rats were divided into 4 groups. Hindlimb ischemia was achieved by clamping the common femoral artery in 3 of the groups, but not a control group. OXY was injected before ischemia in the preoperative (preop) I/R + OXY group and after the onset of ischemia in the postoperative (postop) I/R + OXY group. Saline solution was injected in the I/R group. Limbs were rendered ischemic for 90 min. At the end of 90-min reperfusion period, skeletal muscle tissue samples were taken from the ischemic muscle for evaluation at light and transmission electron microscopic levels. Biochemical analysis was done for malonedialdehyde and glutathione levels. Caspase immunohistochemistry was applied for apoptosis. The light- and electron-microscopic scores of the OXY-treated groups were significantly lower than in the I/R group. The degree of tissue damage was ameliorated in the OXY-treated groups. The number of apoptotic cells was decreased in the OXY-treated groups compared with the I/R group. In OXY-treated groups, the malonedialdehyde level was lower than in the I/R group. Glutathione levels were found to be increased in the OXY-treated groups compared with the I/R group. Oxytocin has a protective effect against I/R injury in skeletal muscle and may reduce the incidence of compartment syndrome.

Resveratrol Supplementation Does Not Improve Metabolic Function in Nonobese Women with Normal Glucose Tolerance

Resveratrol has been reported to improve metabolic function in metabolically abnormal rodents and humans, but it has not been studied in nonobese people with normal glucose tolerance. We conducted a randomized, double-blind, placebo-controlled trial to evaluate the metabolic effects of 12weeks of resveratrol supplementation (75mg/day) in nonobese, postmenopausal women with normal glucosetolerance. Although resveratrol supplementation increased plasma resveratrol concentration, it did not change body composition, resting metabolic rate, plasma lipids, or inflammatory markers. A two-stage hyperinsulinemic-euglycemic clamp procedure, in conjunction with stable isotopically labeled tracer infusions, demonstrated that resveratrol did not increase liver, skeletal muscle, or adipose tissue insulin sensitivity. Consistent with the absence of invivo metabolic effects, resveratrol did not affect its putative molecular targets, including AMPK, SIRT1, NAMPT, and PPARGC1A, in either skeletal muscle or adipose tissue. These findings demonstrate that resveratrol supplementation does not have beneficial metabolic effects innonobese, postmenopausal women with normal glucose tolerance.