EPO-receptor is present in mouse C2C12 and human primary skeletal muscle cells but EPO does not influence myogenesis.

Abstract The role and regulation of the pleiotropic cytokine erythropoietin (EPO) in skeletal muscle are controversial. EPO exerts its effects by binding its specific receptor (EPO-R), which activates intracellular signaling and gene transcription in response to internal and external stress signals. EPO is suggested to play a direct role in myogenesis via the EPO-R, but several studies have questioned the effect of EPO treatment in muscle in vitro and in vivo. The lack of certainty surrounding the use of nonspecific EPO-R antibodies contributes to the ambiguity of the field. Our study demonstrates that the EPO-R gene and protein are expressed at each stage of mouse C2C12 and human skeletal muscle cell proliferation and differentiation and validates a specific antibody for the detection of the EPO-R protein. However, in our experimental conditions, EPO treatment had no effect on mouse C2C12 and human muscle cell proliferation, differentiation, protein synthesis or EPO-R expression. While an increase in Akt and MAPK phosphorylation was observed, we demonstrate that this effect resulted from the stress caused by changing medium and not from EPO treatment. We therefore suggest that skeletal muscle EPO-R might be present in a nonfunctional form, or too lowly expressed to play a role in muscle cell function

A Generalized Discrete Event System (G-DEVS) Flattened Simulation Structure: Application to High-Level Architecture (HLA) Compliant Simulation of Workflow

International audienceThe objective of the paper is to specify a new flattened Generalized Discrete Event System simulation engine structure and the Workflow modeling and simulation environment embedding it. We express first the new flattened simulation structure and give the corresponding transformation functions. We analyze performance tests conducted on this new simulation structure to measure its efficiency. Then, having selected the essential concepts in the elaboration of the Workflow, we present a language of description to define the Workflow processes. Finally, we define a distributed Workflow Reference Model that interfaces components of the Workflow with respect to the High-Level Architecture standard. Today enterprises can take advantage of this platform in the context of networking where interoperability, flexibility, and efficiency are challenging concepts

Statin-induced increases in atrophy gene expression occur independently of changes in PGC1α protein and mitochondrial content

One serious side effect of statin drugs is skeletal muscle myopathy. Although the mechanism(s) responsible for statin myopathy remains to be fully determined, an increase in muscle atrophy gene expression and changes in mitochondrial content and/or function have been proposed to play a role. In this study, we examined the relationship between statin-induced expression of muscle atrophy genes, regulators of mitochondrial biogenesis, and markers of mitochondrial content in slow- (ST) and fast-twitch (FT) rat skeletal muscles. Male Sprague Dawley rats were treated with simvastatin (60 or 80 mg·kg(-1)·day(-1)) or vehicle control via oral gavage for 14 days. In the absence of overt muscle damage, simvastatin treatment induced an increase in atrogin-1, MuRF1 and myostatin mRNA expression; however, these were not associated with changes in peroxisome proliferator gamma co-activator 1 alpha (PGC-1α) protein or markers of mitochondrial content. Simvastatin did, however, increase neuronal nitric oxide synthase (nNOS), endothelial NOS (eNOS) and AMPK α-subunit protein expression, and tended to increase total NOS activity, in FT but not ST muscles. Furthermore, simvastatin induced a decrease in β-hydroxyacyl CoA dehydrogenase (β-HAD) activity only in FT muscles. These findings suggest that the statin-induced activation of muscle atrophy genes occurs independent of changes in PGC-1α protein and mitochondrial content. Moreover, muscle-specific increases in NOS expression and possibly NO production, and decreases in fatty acid oxidation, could contribute to the previously reported development of overt statin-induced muscle damage in FT muscles

Identification of MicroRNAs Linked to Regulators of Muscle Protein Synthesis and Regeneration in Young and Old Skeletal Muscle

Over the course of ageing there is a natural and progressive loss of skeletal muscle mass. The onset and progression of age-related muscle wasting is associated with an attenuated activation of Akt-mTOR signalling and muscle protein synthesis in response to anabolic stimuli such as resistance exercise. MicroRNAs (miRNAs) are novel and important post-transcriptional regulators of numerous cellular processes. The role of miRNAs in the regulation of muscle protein synthesis following resistance exercise is poorly understood. This study investigated the changes in skeletal muscle miRNA expression following an acute bout of resistance exercise in young and old subjects with a focus on the miRNA species predicted to target Akt-mTOR signalling

Ageing has no effect on the regulation of the ubiquitin proteasome-related genes and proteins following resistance exercise

Skeletal muscle atrophy is a critical component of the ageing process. Age-related muscle wasting is due to disrupted muscle protein turnover, a process mediated in part by the ubiquitin proteasome pathway (UPP). Additionally, older subjects have been observed to have an attenuated anabolic response, at both the molecular and physiological levels, following a single-bout of resistance exercise (RE). We investigated the expression levels of the UPP-related genes and proteins involved in muscle protein degradation in 10 older (60-75 years) versus 10 younger (18-30 years) healthy male subjects at basal as well as 2 hours after a single-bout of RE. MURF1, atrogin-1 and FBXO40, their substrate targets PKM2, myogenin, MYOD, MHC and EIF3F as well as MURF1 and atrogin-1 transcriptional regulators FOXO1 and FOXO3 gene and/or protein expression levels were measured via real time PCR and western blotting, respectively. At basal, no age-related difference was observed in the gene/protein levels of atrogin-1, MURF1, myogenin, MYOD and FOXO1/3. However, a decrease in FBXO40 mRNA and protein levels was observed in older subjects, while PKM2 protein was increased in older subjects. In response to RE, MURF1, atrogin-1 and FBXO40 mRNA were upregulated in both the younger and older subjects, with changes observed in protein levels. In conclusion, UPP-related gene/protein expression is comparably regulated in healthy young and old male subjects at basal and following RE. These findings suggest that UPP signalling plays a limited role in the process of age-related muscle wasting. Future studies are required to investigate additional proteolytic mechanisms in conjunction with skeletal muscle protein breakdown measurements following RE in older versus younger subjects

A fast, reliable and sample-sparing method to identify fibre types of single muscle fibres

Abstract Many skeletal muscle proteins are present in a cell-specific or fibre-type dependent manner. Stimuli such as exercise, aging, and disease have been reported to result in fibre-specific responses in protein abundances. Thus, fibre-type-specific determination of the content of specific proteins provides enhanced mechanistic understanding of muscle physiology and biochemistry compared with typically performed whole-muscle homogenate analyses. This analysis, however, is laborious and typically not performed. We present a novel dot blotting method for easy and rapid determination of skeletal muscle fibre type based on myosin heavy chain (MHC) isoform presence. Requiring only small amounts of starting muscle tissue (i.e., 2–10 mg wet weight), muscle fibre type is determined in one-tenth of a 1–3-mm fibre segment, with the remainder of each segment pooled with fibre segments of the same type (I or II) for subsequent protein quantification by western blotting. This method, which we validated using standard western blotting, is much simpler and cheaper than previous methods and is adaptable for laboratories routinely performing biochemical analyses. Use of dot blotting for fibre typing will facilitate investigations of fibre-specific responses to diverse stimuli, which will advance our understanding of skeletal muscle physiology and biochemistry

Erythropoietin Does Not Enhance Skeletal Muscle Protein Synthesis Following Exercise in Young and Older Adults

PURPOSE: Erythropoietin (EPO) is a renal cytokine that is primarily involved in hematopoiesis while also playing a role in non-hematopoietic tissues expressing the EPO-receptor (EPOR). The EPOR is present in human skeletal muscle. In mouse skeletal muscle, EPO stimulation can activate the AKT serine/threonine kinase 1 (AKT) signaling pathway, the main positive regulator of muscle protein synthesis. We hypothesized that a single intravenous EPO injection combined with acute resistance exercise would have a synergistic effect on skeletal muscle protein synthesis via activation of the AKT pathway. METHODS: Ten young (24.2 ± 0.9 years) and 10 older (66.6 ± 1.1 years) healthy subjects received a primed, constant infusion of [ring-13C(6)] L-phenylalanine and a single injection of 10,000 IU epoetin-beta or placebo in a double-blind randomized, cross-over design. 2 h after the injection, the subjects completed an acute bout of leg extension resistance exercise to stimulate skeletal muscle protein synthesis. RESULTS: Significant interaction effects in the phosphorylation levels of the members of the AKT signaling pathway indicated a differential activation of protein synthesis signaling in older subjects when compared to young subjects. However, EPO offered no synergistic effect on vastus lateralis mixed muscle protein synthesis rate in young or older subjects. CONCLUSIONS: Despite its ability to activate the AKT pathway in skeletal muscle, an acute EPO injection had no additive or synergistic effect on the exercise-induced activation of muscle protein synthesis or muscle protein synthesis signaling pathways

Zastosowanie konserwanta chemicznego do utrwalania probek mleka do badan mikrobiologicznych

lt has been shown that boric preservative (50 g H3B03 and 10 g glycerol in 1 dm3 of solution in distilled water) added in the amount of 1.2 cm3 to 10 cm3 of milk prevents statistically significant changes of the, number of bacteria during 28 h storage of milk at 12°C and 20°C or during 8 h storage at 25°C, irrespective of the initial microbiological quality of milk. The bacteriostatic effect of the preservative on psychrotrophic bacteria persisted for 24 h. The action of the preservative an coliform bacteria varied depending on the quality of milk and storage temperature. In the absence of preservative, the milk kept at 0-2°C (in ice water) did not alter its microbiological quality during storage for 28 h

“My Mind Varied Its Focus Quite a Bit”: A Thematic Analysis of the Attentional Focus of Aspiring Professional Violinists and Violists During Performance

Knowledge about musicians’ attentional focus may shed more light on why some succeed in demonstrating their optimal performance under pressure while others fail to do so. In previous research, attentional focus has not been investigated directly after performance. The aim of this study was to extend and deepen our understanding of the “what” and “how” of musicians’ attentional focus during performance under pressure. Qualitative data provided by 46 violinists and violists in open-format questionnaires immediately after they performed audition excerpts under low- and high-pressure conditions were analyzed using thematic analysis within a constructivist framework. Findings revealed that the focus of upper string players during “real-life” performance may be more dynamic and multifaceted than previous research might suggest. In particular, when participants reported a music-related focus, they referred to the level of formal and technical elements and to the level of interpretation and character, but also to prioritizing between the two levels. They focused on the navigation of these music-related aspects, their physical and emotional performance experience, critical thoughts and attempts at control, and the quality and dynamic of their focus. Furthermore, they described ways of managing their focus in a positive and adaptive sense but also reported negative thoughts, feelings, and sensations. Staying in the present moment and enjoying the music was thus a desirable focus. Approaches based on mindfulness and acceptance may be particularly suited to supporting musicians in maintaining a beneficial attentional focus during performance

Decentralized Approach for Efficient Simulation of Devs Models

Part 1: Knowledge-Based Performance ImprovementInternational audienceThis paper proposes to improve simulation efficiency of DEVS mod- els based on the classical Discrete Event system Specification (DEVS) formalism by reducing the number of messages exchanged between simulators. We propose three changes: hierarchical modeling tree flattening based on closure under cou- pling, direct coupling and decentralized scheduling. The main idea is to relieve coordinators by giving to simulators more tasks to process