Muscle Fiber Damage Research Articles

Udział czynników endokrynnych i komórek macierzystych w regeneracji mięśni szkieletowych*

Streszczenie Proces odbudowy uszkodzonych mięśni szkieletowych obejmuje cztery fazy: degeneracji, odpowiedzi zapalnej i immunologicznej, regeneracji oraz reorganizacji, regulowanych przez wiele cząsteczek o charakterze immuno-endokrynnym oddziałujących na komórki mięśniowe oraz komórki macierzyste mięśni. Do tych cząsteczek należy testosteron (T), który wiążąc się z wewnątrzkomórkowym receptorem androgenowym inicjuje ekspresję mięśniowej izoformy insulinopodobnego czynnika wzrostu 1 (IGF-1Ec). Współdziałanie T i IGF-1Ec stymuluje wzrost i regenerację mięśni z powodu zahamowania apoptozy, nasilenia proliferacji i róż-nicowania SCs. W wyniku starzenia się, dystrofii mięśniowych lub chorób wyniszczających liczba SCs ulega znacznemu obniżeniu. Regularny wysiłek fizyczny zapobiega jej obniżeniu i tym samym podwyższa potencjał regeneracyjny mięśni zarówno u młodych, jak i starszych osób. Jednym z wyzwań współczesnej medycyny jest możliwość wykorzystania komórek macierzystych oraz podłoży imitujących macierz zewnątrzkomórkową w medycynie regeneracyjnej i molekularnej, zwłaszcza w chorobach degeneracyjnych i pourazowej rekonstrukcji mięśni szkieletowych. Celem pracy jest przedstawienie aktualnych informacji na temat molekularnych i komórkowych mechanizmów regeneracji mięśni szkieletowych, roli testosteronu i czynników wzrostu w aktywacji SCs oraz możliwości ich terapeutycznego wykorzystania w stymulacji odbudowy uszkodzonych włókien mięśniowych.

The Effect of G. Lucidum on the Lifespan of Caenorhabditis Elegans modeling Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X chromosome-linked disease characterized by progressive physical disability, immobility, and premature death in affected boys. Underlying the devastating symptoms of DMD is the loss of dystrophin, a structural protein that connects the extracellular matrix to the cell cytoskeleton and provides protection against contraction-induced damage in muscle cells, leading to chronic peripheral inflammation. However, dystrophin is expressed in neurons within specific brain regions, including the hippocampus, a structure associated with learning and memory formation. Linked to this, a subset of boys with DMD exhibit progressing cognitive dysfunction, with deficits in verbal, short-term, and working memory. Furthermore, in the genetically comparable dystrophin-deficient mouse model of DMD, some, but not all, types of learning and memory are deficient and specific deficits in synaptogenesis and channel clustering at synapses has been noted. Little consideration has been given to the cognitive deficits associated with DMD compared with the research conducted into the peripheral effects of dystrophin deficiency. Therefore, this review focuses on what is known about the role of full-length dystrophin (Dp427) in the hippocampal neurons. In this experiment, I hypothesized that 100 ug/ml of G. Lucidum would extend the lifespan and too much concentration of this herbal medicine would lose its efficacy in treating this disease. A study was conducted through the reactions and lifespan of Caenorhabditis Elegans exhibiting the lack of dystrophin to the different concentrations of G. Lucidum. As a result, the effect of G. Lucidum on the Caenorhabditis Elegans modeling Duchenne Muscular Dystrophy was astonishing as 100 ug/ml of G. Lucidum helped prolong the lifespan of these nematodes by 20%. This data can be reflected onto the lifespan of humans with DMD as the 20% increase in lifespan of these nematodes could mean the prolonged life of 6-8 years for humans. However, too much concentration of G. Lucidum was shown not to affect the life of the worms. The hypothesized argument was proven correct as the results show the 20% increase of lifespan for the 100ug/ml of G. Lucidum concentration and the effect of too much concentration of this herbal method. Moreover, the use of herbal medicine like G. Lucidum could be a new inexpensive and attainable method of treatment for those diagnosed with DMD. The importance of dystrophin in learning and memory is assessed, and the potential importance that inflammatory mediators, which are chronically elevated in dystrophinopathies, may have on hippocampal function is also evaluated

Infection-associated decrease of serum creatine kinase levels in Fukuyama congenital muscular dystrophy

BackgroundMarked decreases in serum creatine kinase levels have been noted in Duchenne and Becker muscular dystrophies as rare complications of autoimmune or autoinflammatory diseases. Subjects and methodsThe influence of systemic inflammation on serum creatine kinase levels was reviewed from the charts of three subjects with Fukuyama congenital muscular dystrophy. ResultsA total of 30 infectious events were identified. Elevated serum C-reactive protein levels coincided with decreased creatine kinase levels on 19 occasions. In one subject, administration of 2 mg/kg/d prednisolone for bronchial asthma resulted in a decrease in creatine kinase level on six other occasions. ConclusionApart from an increase in endogenous cortisol secretion, certain inflammation-related molecules could play a role in mitigating muscle cell damage in Fukuyama congenital muscular dystrophy during febrile infectious episodes. Corticosteroids may be a promising agent for the treatment of muscular symptoms in this disorder.

Lgr5 Marks Adult Progenitor Cells Contributing to Skeletal Muscle Regeneration and Sarcoma Formation

Regeneration of adult skeletal muscle is driven largely by resident satellite cells, a stem cell population increasingly considered to display a high degree of molecular heterogeneity. In this study, we find that Lgr5, a receptor for Rspo and a potent mediator of Wnt/β-catenin signaling, marks a subset of activated satellite cells that contribute to muscle regeneration. Lgr5 is found to be rapidly upregulated in purified myogenic progenitors following acute cardiotoxin-induced injury. Invivo lineage tracing using our Lgr5-2ACreERT2R26tdTomatoLSL reporter mouse model shows that Lgr5+ cells can reconstitute damaged muscle fibers following muscle injury, as well as replenish the quiescent satellite cell pool. Moreover, conditional mutation in Lgr52ACreERT2;KrasG12D;Trp53flox/flox mice drives undifferentiated pleomorphic sarcoma formation in adult mice, thereby substantiating Lgr5+ cells as a cell of origin of sarcomas. Our findings provide the groundwork for developing Rspo/Wnt-signaling-based therapeutics to potentially enhance regenerative outcomes of skeletal muscles in degenerative muscle diseases.

In vivo Ca2+ dynamics during cooling after eccentric contractions in rat skeletal muscle.

The effect of cooling on in vivo intracellular calcium ion concentration [Ca2+]i after eccentric contractions (ECs) remains to be determined. We tested the hypothesis that cryotherapy following ECs promotes an increased [Ca2+]i and induces greater muscle damage in two muscles with substantial IIb and IIx fiber populations. The thin spinotrapezius (SPINO) muscles of Wistar rats were used for in vivo [Ca2+]i imaging, and tibialis anterior (TA) muscles provided greater fidelity and repeatability of contractile function measurements. SPINO [Ca2+]i was estimated using fura 2-AM and the magnitude, location, and temporal profile of [Ca2+]i determined as the temperature near the muscle surface post-ECs was decreased from 30°C (control) to 20°C or 10°C. Subsequently, in the TA, the effect of post-ECs cooling to 10°C on muscle contractile performance was determined at 1 and 2 days after ECs. TA muscle samples were examined by hematoxylin and eosin staining to assess damage. In SPINO, reducing the muscle temperature from 30°C to 10°C post-ECs resulted in a 3.7-fold increase in the spread of high [Ca2+]i sites generated by ECs (P < 0.05). These high [Ca2+]i sites demonstrated partial reversibility when rewarmed to 30°C. Dantrolene, a ryanodine receptor Ca2+ release inhibitor, reduced the presence of high [Ca2+] sites at 10°C. In the TA, cooling exacerbated ECs-induced muscle strength deficits via enhanced muscle fiber damage (P < 0.05). By demonstrating that cooling post-ECs potentiates [Ca2+]i derangements, this in vivo approach supports a putative mechanistic basis for how postexercise cryotherapy might augment muscle fiber damage and decrease subsequent exercise performance.

Physical and chemical effects of ultrasonic cavitation on the grain of meat when lamb salting

The data of a study of the influence of ultrasonic lamb salting on the grain of meat raw materials are presented. It has been established, that at ultrasonic salting with a frequency of 35 kHz, structural damage and turgescence of muscle fibers, as well as local destruction of the sarcolemma with the pronounced rugosity are observed, besides the cross-striation is poorly expressed, and the tissue structure is disturbed. An ultrasonic lamb salting with a frequency of 26 kHz is attended by an increase in quantity of crevices and transverse microcracks, loosening up of muscle fibers, formation of cavities between them while maintaining muscle tissue structure, which facilitates the penetration of brine between and inside the muscle fibers. It allows us to recommend ultrasonic treatment at a frequency of 26 kHz for activation of the brine to intensify the technological process wet of lamb salting.

6-shogaol suppresses oxidative damage in L6 muscle cells

Ginger (Zingiber Officinale Roscoe) has been known reduce muscle pain after exercise, and 6-shogaol {(E)-1-(4-Hydroxy-3-methoxyphenyl)dec-4-en-3-one)} is the major essential oil contained in ginger. In this study, the protective effect of 6-shogaol on L6 muscle cells against oxidative damage was measured. 6-shagol inhibited the damage of L6 cell induced by H2O2, and allowed the increase in mRNA and protein expression levels of intracellular HO-1 and NRF2. 6-shogaol also reduced the production of intracellular ROS. These results suggested that 6-shagol effectively inhibits oxidative damage of skeletal muscle cell.

Molecular Mechanisms of Action of Emodin: As an Anti-Cardiovascular Disease Drug.

Emodin is a natural occurring anthraquinone derivative isolated from roots and barks of numerous plants, molds, and lichens. It is found to be an active ingredient in different Chinese herbs including Rheum palmatum and Polygonam multiflorum, and it is a pleiotropic molecule with diuretic, vasorelaxant, anti-bacterial, anti-viral, anti-ulcerogenic, anti-inflammatory, and anti-cancer effects. Moreover, emodin has also been shown to have a wide activity of anti-cardiovascular diseases. It is mainly involved in multiple molecular targets such as inflammatory, anti-apoptosis, anti-hypertrophy, anti-fibrosis, anti-oxidative damage, abnormal, and excessive proliferation of smooth muscle cells in cardiovascular diseases. As a new type of cardiovascular disease treatment drug, emodin has broad application prospects. However, a large amount of evidences detailing the effect of emodin on many signaling pathways and cellular functions in cardiovascular disease, the overall understanding of its mechanisms of action remains elusive. In addition, by describing the evidence of the effects of emodin in detail, the toxicity and poor oral bioavailability of mice have been continuously discovered. This review aims to describe a timely overview of emodin related to the treatment of cardiovascular disease. The emphasis is to summarize the pharmacological effects of emodin as an anti-cardiovascular drug, as well as the targets and its potential mechanisms. Furthermore, the treatment of emodin compared with conventional cardiovascular drugs or target inhibitors, the toxicity, pharmacokinetics and derivatives of emodin were discussed.

Abstract 478: Connexin-43 Reduction Rescues Cardiac and Skeletal Muscle Pathology in a Novel Mouse Model of Duchenne Muscular Dystrophy Symptomatic Carriers

Duchenne muscular dystrophy (DMD) and its associated cardiomyopathy manifest in 8-10% of all female carriers however research remains male-centric. Although underrepresented, symptomatic females face the risk of cardiac, respiratory, and skeletal muscle problems. Basic research and clinical trials exclude female carriers therefore developments in treatment expose females to unknown safety and efficacy issues. The bottleneck is largely due to the absence of a faithful mouse model. To generate a mouse model, we injected mdx embryonic stem cells (ESCs) into wild-type (WT) blastocysts ( mdx /WT chimera). The cardiac and skeletal muscle phenotype recapitulates the same generated as a consequence of x-inactivation in human manifesting female patients. In the heart, mdx /WT chimeras develop fibrotic cardiomyopathy. In the skeletal muscle, we found evidence of fibrosis, inflammation and muscle weakness. We found that Connexin-43 (Cx43), the primary gap junctional protein in the heart, was pathologically enhanced and remodeled in mdx /WT chimeras. Cx43 was also enhanced in the dystrophic skeletal muscle. Genetic reduction of Cx43-copy number protected mdx /WT chimeras from cardiac and skeletal muscle fiber damage. The latter result was unexpected because Cx43 is not expressed in mature muscle fibers. Upon further investigation, Cx43 was localized to the mononuclear cells invading the interstitial space between dystrophic skeletal muscle fibers. Pathologically enhanced activity of Cx43 in mdx FACS-macrophages was observed via ethidium bromide uptake and the Cx43 hemichannel peptide mimetic, Gap19, inhibited Cx43 function in a dose-dependent manner. Because an excess of Cx43 has been associated with cell death, we believe that Cx43 reduction in invading mdx macrophages benefits the skeletal muscle of understudied DMD carriers, perhaps by a paracrine mechanism involving macrophage-skeletal muscle fiber communication.

Basement membrane recovery process in rat soleus muscle after exercise-induced muscle injury

ABSTRACT Purpose: Collagen IV is a component of the basement membrane (BM) that provides mechanical support for muscle fibers. In addition, transcription factor 4 (TCF4) is highly expressed in muscle connective tissue fibroblasts and regulates muscle regeneration. However, the expression of collagen IV and TCF4 (+) cells in response to exercise-induced muscle injury is not well known. Here, we investigated the expression and localization of collagen IV and TCF4 (+) cells during the recovery process after muscle injury induced by different exercise loads. Materials and Methods: Muscle injury was observed in the soleus muscle of young Wistar rats after 12 or 18 sets—downhill running (DR) on a treadmill. After running, the rats were permitted to recover for a period of 0.5 days, 2 days, or 7 days. Results: Ectopic localization of collagen IV in injured muscle fibers was observed after DR, and the number increased at 0.5 days after 18 sets DR and at 2 days after 12 or 18 sets DR as compared to the number observed at baseline. BM disruption was observed after DR. TCF4 (+) cells appeared in the inside and around injured muscle fibers at 0.5 day of recovery. After 18 sets DR, TCF4 (+) cells were more abundant for a longer period than that observed after 12 sets DR. Conclusions: DR induces BM disruption accompanied by muscle fiber damage. It is possible that BM destruction may be accompanied by muscle damage and that TCF4 (+) cells contribute to muscle fiber and BM recovery.

Mitochondrial Dysfunction Is an Early Consequence of Partial or Complete Dystrophin Loss in mdx Mice.

Duchenne muscular dystrophy (DMD) is characterized by rapid wasting of skeletal muscle. Mitochondrial dysfunction is a well-known pathological feature of DMD. However, whether mitochondrial dysfunction occurs before muscle fiber damage in DMD pathology is not well known. Furthermore, the impact upon heterozygous female mdx carriers (mdx/+), who display dystrophin mosaicism, has received little attention. We hypothesized that dystrophin deletion leads to mitochondrial dysfunction, and that this may occur before myofiber necrosis. As a secondary complication to mitochondrial dysfunction, we also hypothesized metabolic abnormalities prior to the onset of muscle damage. In this study, we detected aberrant mitochondrial morphology, reduced cristae number, and large mitochondrial vacuoles from both male and female mdx mice prior to the onset of muscle damage. Furthermore, we systematically characterized mitochondria during disease progression starting before the onset of muscle damage, noting additional changes in mitochondrial DNA copy number and regulators of mitochondrial size. We further detected mild metabolic and mitochondrial impairments in female mdx carrier mice that were exacerbated with high-fat diet feeding. Lastly, inhibition of the strong autophagic program observed in adolescent mdx male mice via administration of the autophagy inhibitor leupeptin did not improve skeletal muscle pathology. These results are in line with previous data and suggest that before the onset of myofiber necrosis, mitochondrial and metabolic abnormalities are present within the mdx mouse.

Characterization of Pectoralis Major Muscle Satellite Cell Population Heterogeneity, Macrophage Density, and Collagen Infiltration in Broiler Chickens Affected by Wooden Breast.

Muscle satellite cells (MSCs) are myogenic stem cells that play a critical role in post-hatch skeletal muscle growth and regeneration. Activation of regeneration pathways to repair muscle fiber damage requires both the proliferation and differentiation of different MSC populations as well as the function of resident phagocytic cells such as anti-inflammatory and pro-inflammatory macrophages. The Wooden Breast (WB) phenotype in broiler chickens is characterized by myofiber degeneration and extensive fibrosis. Previous work indicates that the resident MSC populations expressing the myogenic regulatory factors, Myf-5 and Pax7 are larger and more proliferative in broilers severely affected with WB vs. unaffected broilers. To further characterize the cellular and molecular changes occurring in WB-affected muscles, samples from pectoralis major (PM) muscles with varying severity of WB (WB score 0 = normal; 1 = mildly affected; 2 = severely affected) were collected at 25 and 43 days post-hatch (n = 8 per score per age) and processed for cryohistological and protein expression analyses. Collagen per field and densities of macrophages and MyoD+, Myf-5+, and Pax7+ MSC populations were quantified on immunofluorescence-stained cryosections. Relative collagen protein expression was quantified by fluorescent Western Blotting. In both 25 and 43-days-old broilers, the proportion of collagen per field (P ≤ 0.021) and macrophage density (P ≤ 0.074) were greater in PM exhibiting severe WB compared with normal. At day 43, populations of MyoD+, Myf-5+:MyoD+ MSC were larger and relative collagen protein expression was greater in WB-affected vs. unaffected broilers (P ≤ 0.05). Pax7+ MSC relative to total cells was also increased as WB severity increased in 43-days-old broilers (P ≤ 0.05). Densities of Myf-5+ (P = 0.092), MyoD+ (P = 0.030), Myf5+:MyoD+ (P = 0.046), and Myf-5+:MyoD+:Pax7+ (P = 0.048) MSC were greater in WB score 1 birds compared with WB score 0 and 2 birds. Overall, alterations in the resident MSC and macrophage populations and collagen protein content were observed in WB-affected muscle. Further investigation will be required to determine how these changes in cell population kinetics and local autocrine and paracrine signaling are involved in the apparent dysregulation of muscle maintenance in WB-affected broilers.

Ca2+‐induced Complex I Inactivity: A Model for Early Mitochondrial Dysfunction Following Volumetric Muscle Loss Injury

Calcium (Ca2+) is a secondary messenger, responsible for the regulation of a plethora of metabolic pathways that must be tightly regulated to avoid cytotoxicity 1. During early stage volumetric muscle loss (VML) injuries, damaged muscle fibers are open to the extracellular environment until the myofiber can be sealed, a process that may take hours 2– 3. This allows for free Ca2+ exchange between intra‐ and extracellular environments to concentrations beyond those appropriate for cell homeostasis. The purpose of this study was to model the changes in mitochondrial metabolism of early VML injuries as a response to a drastic increase of intracellular Ca2+.C57BL6 mice underwent unilateral surgery to create a VML defect in the gastrocnemius muscle, as approved by the University of Georgia’s Institutional Animal Care and Use Committee. Animals were sacrificed via CO2 inhalation, 18 hrs. following surgery. Total [Ca2+] per kg of tissue ([Ca2+]TWM) was measured using a BAPTA complexation assay. Gastrocnemius muscles from naïve mice were dissected into individual fiber bundles, permeabilized, and washed in either normal isotonic or Ca2+‐supplemented medium. Mitochondrial metabolic function and mitochondrial membrane potential were measured through oxygen consumption and Safranin‐O fluorescence rates, respectively, in a High‐Resolution Fluoro‐respirometer.[Ca2+]TWM was elevated in VML‐injured tissue, as expected (n=3, p&lt; 0.05). Acute Ca2+ exposure negatively affected Complex I (C‐I) activity of the electron transport chain. Specifically, C‐I activity was targeted by the addition of glutamate and malate (Glu‐Mal) and confirmed by the sequential addition of C‐I inhibitor Rotenone (Rot). In normal fibers, respiration increased after Glu‐Mal addition and subsequently decreased significantly following Rot, while Ca2+‐incubated fibers exhibited no change in oxygen consumption rate. Succinate (Succ) was used to rescue respiratory function by bypassing C‐I. Succ addition significantly increased oxygen consumption in both normal and Ca2+‐incubated fibers (n=3, p&lt;0.01), confirming a C‐I dysfunction in Ca2+‐treated fibers. Safranin fluorescence is sensitive to changes in mitochondrial membrane potential, decreasing with complex activity and increasing upon inhibition. In normal fibers, Safranin signal decreased with Glu‐Mal and Succ additions and increased with Rot, as expected. However, Ca2+‐treated fibers were only sensitive to Succ treatment, further supporting C‐I dysfunction (n=3, p&lt; 0.01).Herein, we show that an acute increase in intracellular Ca2+ negatively affects the process of oxidative phosphorylation within the mitochondria by disturbing the electron potential and inactivating Complex I. This alteration in membrane potential and decrease in complex activity may be the first step in a systematic shut down of mitochondrial metabolic function that leaves the muscle remaining after injury beyond the hope of effective repair.Support or Funding InformationFunded through the Department of Defense Neuromusculoskeletal Injuries Rehabilitation Research Award W81XWH‐18‐1‐0710 to SMG (UMinn) and JAC (UGA)A‐ Quantification of internal [Ca2+] of VML‐injured and control gastrocnemius muscles using BAPTA absorbance (n=3, p &lt; 0.05). B‐ Oxygen consumption rates of control and Ca2+‐treated muscle fibers after Complex I activation, inhibition, and bypass, respectively (n=3 in duplicate, p &lt; 0.05). C‐ Safranin‐O signal fluctuation in control and Ca2+‐treated muscle fibers after Complex I activation, inhibition, and bypass, respectively (n=3, p&lt; 0.05).Figure 1

Investigation on Pneumotoxicity Induced by Pyrrolizidine AlkaloidsInvestigation on Pneumotoxicity Induced by Pyrrolizidine Alkaloids

Pyrrolizidine alkaloids (PAs) are most common phytotoxins. Apart from their extensively reported hepatotoxicity, few PAs, such as MCT, are also reported to cause lung injury. However, whether different PAs commonly lead to pneumotoxicity remains largely unknown whether different PAs. PAs require metabolic activation to exert toxicity. Hepatic cytochrome P450s are proposed to be responsible for bioactivation of PAs to reactive dehydro‐PAs, which interact with proteins to form pyrrole‐protein adducts causing intrahepatic cytotoxicity. However, the mechanisms underlying pneumotoxicity of PAs, especially the site of metabolic activation of PAs, have not been delineated. Here we aimed to investigate pneumotoxicity of different types of PAs and also identify the contribution of hepatic P450s and extrahepatic P450s to metabolic bioactivation of PAs.Pulmonary toxicity of four representative PAs of both retronecine and otonecine types and Gynura Segetum (GS) alkaloid extract containing two retronecine type PAs, to mimic human PA poisoning, were investigated. Rats were orally administered with representative PAs and GS at 0.2 mmol/kg for 48 hours. Biochemical and histological examinations were applied to evaluate PA‐induced toxicity in liver and lung. The results showed that all PAs induced liver injury to varied levels. Significant lung lesions including pulmonary arterial hypertrophy, capillary congestion, endothelium damage, and abnormal proliferation of smooth muscle cells were found in all PA‐treated groups, demonstrating that both retronecine and otonecine types of PAs can cause pulmonary toxicity.Further to delineate the role of hepatic and extrahepatic CYPs in metabolic bioactivation of PAs, mice with conditional deletion of cytochrome P450 reductase (Cpr) gene and resultant dysfunctional P450s were used. After oral exposure to MCT (120 mg/kg), a well‐known pneumotoxic PA, metabolic activation and pneumotoxicity of MCT among wild‐type (WT), liver‐specific Cpr‐null (LCN), and extrahepatic Cpr‐knockdown (XhCL) mice were compared. The results demonstrated that comparing with WT mice, pyrrole‐protein adducts were significantly decreased (by &gt;60%) in the serum, liver and lungs in LCN mice but unchanged in XhCL mice. In addition, comparing with WT mice, MCT‐exposed LCN mice had significantly higher blood concentration of the intact MCT. Consistently, lung injury represented by vasculature damage was observed in WT and XhCL mice but not in LCN mice. All the data confirmed that hepatic CYPs, not extrahepatic CYPs, were responsible for metabolic activation of PAs.To conclude, the present study for the first time demonstrated that PAs can commonly induce lung injury, which is dependent on the metabolic activation mediated by functional hepatic CYPs.Support or Funding InformationThe present study was supported by General Research Fund (GRF Project No. 14160817) from Research Grants Council of Hong Kong Special Administrative Region.

High pressure‐assisted vacuum‐freeze drying: A novel, efficient way to accelerate moisture migration in shrimp processing

High pressure processing (HPP), as nonthermal processing technology, has the potential to increase the drying rate due to its improvement of heat and mass exchange in different processes. In this study, the moisture migration in shrimps during HPP-vacuum-freeze drying (HPP-VFD) processes has been monitored by using low-field nuclear magnetic resonance and magnetic resonance image (MRI) in comparison with hot air-drying and VFD. Based on the T2 relaxation spectra, three water fractions corresponding to bound water (hydrogen-bonded water), immobile water (water trapped by organization structure or cell member), and free water were observed. For group B, with increasing drying time (4 to 22 hr), the transverse relaxation times of T21 , T22 , and T23 were significantly decreased (76.79%, 57.78%, and 40.9%) (P < 0.05). The content of immobile water (A22 ) and free water (A23 ) decreased (81.55% and 89.07%), whereas the bound water (A21 ) increased (7.26%). In comparison with group B, the T21 , T22 , and T23 of group C showed greater decrease (83.12%, 87.12%, and 89.57% for group C) so that HPP pretreatment could shorten the relaxation time. MRI analysis further proved that HPP-VFD drying has improved drying efficiency, and moisture migration was from the exterior to the interior part with increasing drying time. SEM analysis demonstrated that no significant damage of muscle fibers with narrower gaps was observed for groups B and C. Overall, HPP, as a pretreatment technology, could accelerate the moisture migration and improve the drying efficiency of VFD process for shrimp. PRACTICAL APPLICATION: High pressure processing (HPP) is now well known as a nonthermal processing technology and becoming increasingly acknowledged. However, there is limited information about its application in shrimp-drying process and the moisture dynamic of shrimp subjected to high pressure processing-assisted vacuum-freeze drying. This study could provide valuable information regarding the moisture status and migration in HPP-VFD shrimp monitored by LF-NMR and MRI methods. The results showed that HPP processing at 550MPa for 10min can be used as an interesting method for drying pretreatment, increasing its drying rate and consequently reducing its process time, and it demonstrated that the methods used in this study had good correlation coefficient with physicochemical properties of shrimp, which may be real-time and nondestructive monitoring methods for shrimp-drying process.

Connexin-43 reduction prevents muscle defects in a mouse model of manifesting Duchenne muscular dystrophy female carriers

Duchenne muscular dystrophy (DMD) is a severe X-linked neuromuscular disorder that affects males. However, 8% of female carriers are symptomatic and underrepresented in research due to the lack of animal models. We generated a symptomatic mouse model of DMD carriers via injection of mdx (murine DMD) embryonic stem cells (ESCs) into wild-type (WT) blastocysts (mdx/WT chimera). mdx/WT chimeras developed cardiomyopathic features and dystrophic skeletal muscle phenotypes including elevated mononuclear invasion, central nucleation, fibrosis and declined forelimb grip strength. The disease was accompanied by connexin-43 (Cx43) aberrantly enhanced in both cardiac and skeletal muscles and remodeled in the heart. Genetic reduction of Cx43-copy number in mdx/WT-Cx43(+/−) chimeras protected them from both cardiac and skeletal muscle fiber damage. In dystrophic skeletal muscle, Cx43 expression was not seen in the fibers but in adjacent F4/80+ mononuclear cells. Ethidium Bromide uptake in purified F4/80+/CD11b+ mdx macrophages revealed functional activity of Cx43, which was inhibited by administration of Gap19 peptide mimetic, a Cx43 hemichannel-specific inhibitor. Thus, we suggest that Cx43 reduction in symptomatic DMD carrier mice leads to prevention of Cx43 remodeling in the heart and prevention of aberrant Cx43 hemichannel activity in the skeletal muscle macrophages neighboring Cx43 non-expressing fibers.

Calcinosis Biomarkers in Adult and Juvenile Dermatomyositis.

Dermatomyositis (DM) is a rare idiopathic inflammatory myopathy characterized by muscle weakness and cutaneous manifestations in adults and children. Calcinosis, a complication of DM, is the abnormal deposition of insoluble calcium salts in tissues, including skin, subcutaneous tissue, tendons, fascia, and muscle. Calcinosis is more commonly seen in juvenile DM (JDM), but also develops in adult DM. Although the mechanism of calcinosis remains unclear, several pathogenic hypotheses have been proposed, including intracellular accumulation of calcium secondary to an alteration of the cellular membrane by trauma and inflammation, local vascular ischemia, dysregulation of mechanisms controlling the deposition and solubility of calcium and phosphate, and mitochondrial damage of muscle cells. Identifying calcinosis biomarkers is important for early disease detection and risk assessment, and may lead to novel therapeutic targets for the prevention and treatment of DM-associated calcinosis. In this review, we summarize myositis autoantibodies associated with calcinosis in DM, histopathology and chemical composition of calcinosis, genetic and inflammatory markers that have been studied in adult DM and JDM-associated calcinosis, as well as potential novel biomarkers.

Lateral pharyngoplasty techniques for obstructive sleep apnea syndrome: a comparative experimental stress test of two different techniques.

To show the different effects of expansion sphincter pharyngoplasty (ESP) and barbed reposition pharyngoplasty (BRP) on muscle tension and muscle fiber tearing using a comparative experimental stress test with a frog thigh muscle model. Frog thigh muscle was used for this experimental study. A Barbed suture was used to simulate the BRP pharyngoplasty whereas a Vicryl 3-0 suture was used to simulate the ESP technique. The other extremity of the suture was attached to traction scales. The traction scales were used to measure the weight relative to the amount of force required to obtain muscle breaking. Both surgical techniques were simulated on the frog muscle. Traction was performed until muscle breaking was observed, measuring the value of force needed to obtain muscle rupture. Specimen muscle breakdown in the ESP simulation occurred with an average value of 0.7kg of traction force. Contrarily, specimen muscle breakdown in the BRP simulation with Barbed suture occurred with an average value of 1.5kg of traction force CONCLUSION: During simulation of the ESP technique, specimen muscle breakdown occurred with an average value of traction force lower than in the BRP technique. During traction the multiple lateral sustaining suture loops of BRP could ensure greater stability then the single pulling tip suture of ESP with minor risk of muscle fiber damage.

Adrenomedullin expression in aortic artery wall of diabetic rats given alpha lipoic acid.

Diabetes mellitus (DM) is a major health problem predisposing to cardiovascular diseases. The aim of this study was to investigate the effects of alpha lipoic acid (ALA) on both the arterial wall of diabetic rats and the adrenomedullin (ADM) gene expression. Twenty-four Wistar Albino rats were divided into three groups as Control, DM + S, and DM + ALA. For DM model, a single dose of 40mg/kg streptozotocin, for DM + ALA group, 100mg/kg/day/4weeks was administered. Hematoxylin & Eosin (H&E) staining was done and vascular endothelial growth factor (VEGF) was detected by immunohistochemical analysis in the artery wall. Total damage score of vessel wall (endothelial cell damage, media layer smooth muscle cell damage, and internal elastic lamina damage) and H score (immunoreactivity intensity) were calculated. Expression of ADM gene was measured by qRT-PCR. In DM + S group, Total damage score of vessel wall were detected by light microscopy. There were statistically significant differences between the groups Control/DM + S and DM + S/DM + ALA in terms of the vessel total damage score and H score (p < 0.005). ADM expression was increased threefold in both DM + S and DM + ALA groups compared to the control group (p < 0.05). ALA may have positive effect on the vessel damage in diabetic rats. However, no significant decrease in ADM expression levels was observed in diabetic rats after ALA administration and we considered that the protective effect of ALA is independent of adrenomedullin. Further studies with different doses and durations of ALA administrations are required to investigate the changes in ADM expression.

Large increases in plasma fast skeletal muscle troponin I after whole-body eccentric exercises

ObjectivesIt has been reported that plasma fast skeletal muscle troponin I (fsTnI) but not slow skeletal muscle troponin I (ssTnI) increases after a bout of eccentric exercise of the elbow flexors. The present study compared the first and second bouts of whole-body eccentric exercises for changes in plasma fsTnI and ssTnI concentrations. DesignObservational study in an experimental group. MethodsFifteen sedentary men (20–25 y) performed nine eccentric exercises targeting arm, leg and trunk muscles, and repeated them two weeks later. Blood samples were taken before and for five days following each bout, and plasma ssTnI and fsTnl concentrations were measured by enzyme-linked immunosorbent assays. Their changes were compared between bouts and their relationships to plasma CK activity and myoglobin concentrations were analysed. ResultsPlasma fsTnI concentration increased after the first bout and peaked at 4 days post-exercise (2152–40,295 ng/mL), but no significant increases were evident after the second bout. Plasma ssTnI concentration did not change significantly from the baseline (<0.08 ng/mL) after either bout. Peak plasma fsTnI concentration was significantly (p < 0.005) correlated with peak plasma CK activity (peak: 23,238–207,304 IU/L, r = 0.727) and myoglobin concentration (1047–3936 μg/L, r = 0.625) after the first bout. ConclusionsThese results suggest that plasma TnI concentrations are more specific biomarker of muscle damage than plasma CK activity and myoglobin concentration. It seems that the whole-body eccentric exercises induced damage preferentially to fast-twitch muscle fibres, and increases in plasma CK activity and myoglobin concentration after eccentric exercise may reflect fast-twitch muscle fibre damage.