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  • SKELETAL-MUSCLE  (9)
  • 1
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    Keywords: brain ; RECEPTOR ; CELL ; Germany ; KINASE ; EXPOSURE ; NEW-YORK ; PATIENT ; INDEX ; treatment ; cell culture ; culture ; TRIAL ; PLASMA ; DECREASE ; ATP ; SKELETAL-MUSCLE ; GLUCOSE ; DOUBLE-BLIND ; OXIDATIVE STRESS ; SMOKERS ; OXYGEN ; insulin ; INSULIN-RECEPTOR ; 3T3-L1 ADIPOCYTES ; CREATINE SUPPLEMENTATION ; HYDROGEN-PEROXIDE PRODUCTION ; LOW-CARBOHYDRATE ; obesity,hyperlipidemia,body fat,insulin reactivity,thiol antioxidant treatment ; REDOX STATE ; REVERSES ENDOTHELIAL DYSFUNCTION ; STRESS IMPAIRS INSULIN ; SUPPLEMENTATION ; TYROSINE KINASE DOMAIN
    Abstract: Insulin signaling is enhanced by moderate concentrations of reactive oxygen species (ROS) and suppressed by persistent exposure to ROS. Diabetic patients show abnormally high ROS levels and a decrease in insulin reactivity which is ameliorated by antioxidants, such as N-acetylcysteine (NAC). A similar effect of NAC has not been reported for non-diabetic subjects. We now show that the insulin receptor (IR) kinase is inhibited in cell culture by physiologic concentrations of cysteine. In two double-blind trials involving a total of 140 non-diabetic subjects we found furthermore that NAC increased the HOMA-R index (derived from the fasting insulin and glucose concentrations) in smokers and obese patients, but not in nonobese non-smokers. In obese patients NAC also caused a decrease in glucose tolerance and body fat mass. Simultaneous treatment with creatine, a metabolite utilized by skeletal muscle and brain for the interconversion of ADP and ATP, reversed the NAC-mediated increase in HOMA-R index and the decrease in glucose tolerance without preventing the decrease in body fat. As the obese and hyperlipidemic patients had lower plasma thiol concentrations than the normolipidemic subjects, our results suggest that low thiol levels facilitate the development of obesity. Supplementation of thiols plus creatine may reduce body fat without compromising glucose tolerance
    Type of Publication: Journal article published
    PubMed ID: 15007512
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  • 3
    Keywords: CELLS ; CELL ; Germany ; THERAPY ; PROTEIN ; MOLECULES ; TISSUE ; MICE ; MECHANISM ; TISSUES ; mechanisms ; HEALTH ; Drosophila ; GLUTATHIONE ; PLASMA ; STRESS ; AGE ; NECROSIS-FACTOR-ALPHA ; DAMAGE ; LIFE-SPAN ; CAENORHABDITIS-ELEGANS ; MUSCLE ; PARAMETERS ; SKELETAL-MUSCLE ; DIET ; LIPID-PEROXIDATION ; OXIDATIVE STRESS ; OXYGEN ; antioxidants ; reactive oxygen species ; signaling ; OXIDATIVE-STRESS ; INCREASE ; INSULIN-RECEPTOR ; WEIGHT ; clinical trials ; LIFE ; REACTIVE OXYGEN ; LEVEL ; PROTEIN-TYROSINE PHOSPHATASES ; AGE-RELATED-CHANGES ; function ; LOSSES ; ROS ; PRECURSOR ; age-related decrease in ; ageing related functions ; CALORIE RESTRICTION ; cysteine deficit and ageing ; cysteine supplementation ; GLUTATHIONE REDOX STATE ; improvement of ; insulin receptor signaling and ageing ; limiting availability in old age ; oxidative shift in redox status ; redox signaling 'and ageing ; thiols
    Abstract: The popular use of antioxidative vitamins illustrates the growing awareness of oxidative stress as an important hazard to our health and as an important factor in the ageing process. Superoxide radicals and superoxide-derived reactive oxygen species (ROS) are constantly formed in most cells and tissues. To ensure that ROS can function as biological signaling molecules without excessive tissue damage, ROS are typically scavenged by antioxidants such as glutathione and the vitamins A, C, and E. "Oxidative stress" occurs if the production of ROS is abnormally increased or antioxidant concentrations are decreased. Genetic studies in mice, Drosophila, and Celegans suggested that ageing may be mechanistically linked to oxidative stress. Several manifestations of oxidative stress were shown to increase with age, whereas tissue levels of vitamin E, plasma concentrations of vitamin C, and intracellular glutathione concentrations decrease with age. In at least two independent studies, cysteine supplementation on top of the normal protein diet has shown significant beneficial effects on each of several different parameters relevant to ageing, including skeletal muscle functions. As the quality of life in old age is severely compromised by the loss of skeletal muscle function, and as muscle function can be measured with satisfactory precision, loss of muscle function is one of the most attractive surrogate parameters of ageing. The mechanisms by which a deficit in glutathione and its precursor cysteine contributes to various ageing-related degenerative processes appears to be related largely but not exclusively to the dysregulation of redox-regulated biological signaling cascades
    Type of Publication: Journal article published
    PubMed ID: 17100590
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  • 4
    Keywords: EXPRESSION ; SURVIVAL ; CELL ; Germany ; KINASE ; imaging ; NEW-YORK ; PATIENT ; ACTIVATION ; MARKER ; prognosis ; QUALITY ; TYPE-1 ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; FIBER COMPOSITION ; BREAST-CANCER ; NO ; PERFORMANCE ; PLASMA ; AGE ; genetics ; FIBER ; MUSCLE ; PARAMETERS ; MORPHOLOGY ; SKELETAL-MUSCLE ; PREDICTION ; BODY ; POOR-PROGNOSIS ; heredity ; OXYGEN ; BIOPSY ; exercise ; MASSES ; BODIES ; REGRESSION ; INCREASE ; WEIGHT ; LIFE ; PHYSICAL-ACTIVITY ; HEIGHT ; QUALITY-OF-LIFE ; LEVEL ; MYOPATHY ; PLASMA-LEVELS ; technique ; USA ; LOSSES ; uptake ; correlation ; cachexia ; myopathies ; PREDICT ; BIOPSIES ; INCREASES ; - ; RESONANCE ; CANCER DIAGNOSIS ; TRACK ; FOXO TRANSCRIPTION FACTORS ; cancer cachexia ; muscle biopsy ; muscle morphology ; muscle wasting
    Abstract: Progressive muscle wasting is a central feature of cancer-related cachexia and has been recognized as a determinant of poor prognosis and quality of life. However, until now, no easily assessable clinical marker exists that allows to predict or to track muscle wasting. The present study evaluated the potential of myoglobin (MG) plasma levels to indicate wasting of large locomotor muscles and, moreover, to reflect the loss of MG-rich fiber types, which are most relevant for daily performance. In 17 cancer-cachectic patients (weight loss 22%) and 27 age- and gender-matched healthy controls, we determined plasma levels of MG and creatine kinase (CK), maximal quadriceps muscle cross-sectional area (CSA) by magnetic resonance imaging, muscle morphology and fiber composition in biopsies from the vastus lateralis muscle, body cell mass (BCM) by impedance technique as well as maximal oxygen uptake (VO(2)max). In cachectic patients, plasma MG, muscle CSA, BCM, and VO(2)max were 30-35% below control levels. MG showed a significant positive correlation to total muscle CSA (r=0.65, p 〈 0.001) and to the CSA fraction formed by type 1 and 2a fibers (r=0.80, p 〈 0.001). However, when adjusted for body height and age by multiple regression, MG yielded a largely improved prediction of total CSA (multiple r=0.83, p 〈 0.001) and of fiber type 1 and 2a CSA (multiple r=0.89, p 〈 0.001). The correlations between CK and these muscle parameters were weaker, and elevated CK values were observed in 20% of control subjects despite a prior abstinence from exercise for 5 days. In conclusion, plasma MG, when adjusted for anthropometric parameters unaffected by weight, may be considered as a novel marker of muscle mass (CSA) indicating best the mass of MG-rich type 1 and 2a fibers as well as VO(2)max as an important functional readout. CK plasma levels appear to be less reliable because prolonged increases are observed in even subclinical myopathies or after exercise. Notably, cancer-related muscle wasting was not associated with increases in plasma MG or CK in this study
    Type of Publication: Journal article published
    PubMed ID: 17605115
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  • 5
    Keywords: EXPRESSION ; carcinoma ; Germany ; human ; KINASE ; MODEL ; MODELS ; PATHWAY ; PATHWAYS ; liver ; NEW-YORK ; PROTEIN ; PROTEINS ; SAMPLE ; SAMPLES ; transcription ; TISSUE ; TRANSDUCTION ; PATIENT ; ACTIVATION ; TRANSCRIPTION FACTOR ; CONTRAST ; PHOSPHORYLATION ; protein kinase ; PROTEIN-KINASE ; signal transduction ; SIGNAL ; antibodies ; antibody ; FORM ; TRANSCRIPTION FACTORS ; DECREASE ; genetics ; SIGNAL-TRANSDUCTION ; MUSCLE ; Jun ; DEGRADATION ; SKELETAL-MUSCLE ; ATROPHY ; pancreatic cancer ; heredity ; REGULATOR ; REGULATORS ; BIOPSY ; ANIMAL-MODELS ; CHAIN ; pancreas ; RE ; PANCREATIC-CANCER ; INCREASE ; TUMORIGENESIS ; HEAVY ; PROTEIN-SYNTHESIS ; WEIGHT ; LEVEL ; PHOSPHATIDYLINOSITOL 3-KINASE ; ANIMAL-MODEL ; USA ; LOSSES ; cachexia ; animal ; ACTIN ; animal model ; BIOPSIES ; comparison ; HYPERTROPHY ; FOXO TRANSCRIPTION FACTORS ; Skeletal muscle ; UBIQUITIN LIGASES
    Abstract: In animal models of cachexia, alterations in the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway have been demonstrated in atrophying skeletal muscles. Therefore, we assessed the activity of proteins in this pathway in muscle and liver biopsies from 16 patients undergoing pancreatectomy for suspect of carcinoma. Patients were divided in a non-cachectic or cachectic group according to their weight loss before operation. Extracts of skeletal muscle and liver tissue from eight cachectic patients with pancreas carcinoma and eight non-cachectic patients were analysed by Western blotting using pan- and phospho-specific antibodies directed against eight important signal transduction proteins of the PI3-K/Akt pathway. Muscle samples from cachectic patients revealed significantly decreased levels of myosin heavy chain (-45%) and actin (-18%) in comparison to non-cachectic samples. Akt protein level was decreased by -55%. The abundance and/or phosphorylation of the transcription factors Foxo1 and Foxo3a were reduced by up to fourfold in muscle biopsies from cachectic patients. Various decreases of the phosphorylated forms of the protein kinases mTOR (-82%) and p70S6K (-39%) were found. In contrast to skeletal muscle, cachexia is associated with a significant increase in phosphorylated Akt level in the liver samples with a general activation of the PI3-K/Akt cascade. Our study demonstrates a cachexia-associated loss of Akt-dependent signalling in human skeletal muscle with decreased activity of regulators of protein synthesis and a disinhibition of protein degradation
    Type of Publication: Journal article published
    PubMed ID: 17333095
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  • 6
    Keywords: BLOOD ; Germany ; IN-VIVO ; PERFUSION ; VIVO ; imaging ; SYSTEM ; METABOLISM ; BLOOD-FLOW ; FLOW ; MAGNETIC-RESONANCE ; MAGNETIC-RESONANCE-SPECTROSCOPY ; METABOLITES ; SPECTROSCOPY ; magnetic resonance imaging ; resistance ; ENERGY ; AGE ; SKELETAL-MUSCLE ; KINETICS ; exercise ; methods ; SIZE ; contrast-enhanced ultrasonography ; magnetic resonance spectroscopy ; contrast-enhanced ultrasound ; Skeletal muscle ; INTRAMYOCELLULAR LIPIDS ; AREA ; ADAPTATIONS ; Concentric resistance training ; ENDURANCE
    Abstract: Purpose: While the evidence is conclusive regarding the positive effects of endurance training, there is still some controversy regarding the effects of resistance training on muscular capillarity. Thus, the purpose was to assess whether resistance strength training influences resting skeletal muscle microcirculation in vivo. Materials and methods: Thirty-nine middle-aged subjects (15 female, 24 male; mean age, 54 +/- 9 years) were trained twice a week on an isokinetic system (altogether 16 sessions lasting 50 min, intensity 75% of maximum isokinetic and isometric force of knee flexors and extensors). To evaluate success of training, cross-sectional area (CSA) of the quadriceps femoris muscle and its isokinetic and isometric force were quantified. Muscular capillarization was measured in biopsies of the vastus lateralis muscle. In vivo, muscular energy and lipid metabolites were quantified by magnetic resonance spectroscopy and parameters of muscular microcirculation, such as local blood volume, blood flow and velocity, by contrast-enhanced ultrasound analyzing replenishment kinetics. Results: The significant (P〈0.001) increase in CSA (60 +/- 16 before vs. 64 +/- 15 cm(2) after training) and in absolute muscle strength (isometric, 146 +/- 44 vs. 174 +/- 50 Nm; isokinetic, 151 +/- 53 vs. 174 +/- 62 Nm) demonstrated successful training. Neither capillary density ex vivo (351 +/- 75 vs. 326 +/- 62) nor ultra-sonographic parameters of resting muscle perfusion were significantly different (blood flow, 1.2 +/- 1.2 vs. 1.1 +/- 1.1 ml/min/100 g; blood flow velocity, 0.49 +/- 0.44 vs. 0.52 +/- 0.74 mm s(-1)). Also, the intensities of high-energy phosphates phosphocreatine and beta-adenosintriphosphate were not different after training within the skeletal muscle at rest (beta-ATP/phosphocreatine, 0.29 +/- 0.06 vs. 0.28 +/- 0.04). Conclusion: The significant increase in muscle size and strength in response to concentric isokinetic and isometric resistance training occurs without an increase in the in vivo microcirculation of the skeletal muscles at rest. (C) 2008 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 19144482
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  • 7
    Keywords: AGENTS ; BLOOD ; Germany ; PERFUSION ; DIAGNOSIS ; QUANTIFICATION ; VOLUME ; DISEASE ; TISSUE ; BLOOD-FLOW ; CONTRAST ; SKIN ; blood flow ; CONTRAST AGENT ; FLOW ; PARAMETERS ; SKELETAL-MUSCLE ; KINETICS ; HEALTHY ; SONOGRAPHY ; BOLUS ; POWER DOPPLER SONOGRAPHY ; VASCULARIZATION ; ULTRASOUND-INDUCED DESTRUCTION ; AGENT ; RE ; monitoring ; HEALTHY-VOLUNTEERS ; MICROBUBBLE CONTRAST ; replenishment kinetics ; TUMOR PERFUSION ; PRINCIPLES ; POWER ; contrast-enhanced ; contrast-enhanced ultrasonography ; muscle perfusion ; replenishment kinetics of microbubbles ; venous occlusion plethysmography
    Abstract: Objective. The purpose of this study was to develop a clinically applicable examination method to assess per-fusion of the skeletal muscle using contrast-enhanced ultrasonography (CEUS) analyzing replenishment kinetics of microbubbles. Methods. Power Doppler sonography (7 MHz) after intravenous bolus injection of 10 mL of a microbubble contrast agent was used to repeatedly examine the perfusion of the right biceps muscle at rest and after defined exercise in 10 healthy volunteers. Parameters of perfusion, such as local blood volume, blood flow velocity, and perfusion, were calculated by a modified analysis of replenishment kinetics. For validation, CEUS was correlated with venous occlusion plethysmography (VOP) examining the right forearm flexor muscles at rest and after defined exercise. Results. The CEUS examination was easily feasible and was able to depict the physiologic large variability of the right biceps muscle perfusion at rest (mean +/- SID, 3.0 +/- 2.3 [similar to mL/s (.) 100 mg]) compared with the results after exercise (22.9 +/- 11.0 [similar to mL/s (.) 100 mg]). The perfusion calculated with VOP significantly correlated with the CEUS parameters perfusion (r = 0.81; P 〈 .001) and blood volume (r = 0.82; P 〈 .001). The calculated mean blood flow velocity in the right forearm flexor muscles raised from 0.41 +/- 0.24 mm/s at rest to 0.64 +/- 0.39 mm/s after exercise, showing a significant correlation with the CEUS perfusion (r = 0.72; P 〈 .001). Conclusions. Muscle perfusion can be easily and quantitatively assessed with CEUS. Compared with VOP, CEUS allows for a separate analysis of different muscle groups, unaffected by skin perfusion. Its application may be of particular interest in the diagnosis and monitoring of pathologic microvascularization in myositis or diabetic obstructive disease
    Type of Publication: Journal article published
    PubMed ID: 15784761
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  • 8
    Keywords: CANCER ; CELLS ; EXPRESSION ; tumor ; BLOOD ; Germany ; SYSTEM ; GENE-EXPRESSION ; microarray ; TUMORS ; LINES ; PATIENT ; DNA ; MECHANISM ; prognosis ; CELL-LINES ; cytokines ; antibodies ; antibody ; immunohistochemistry ; DESIGN ; OBESITY ; LINE ; SKELETAL-MUSCLE ; adenocarcinoma ; MICROARRAY ANALYSIS ; OVEREXPRESSION ; PERIPHERAL-BLOOD ; cell lines ; pancreatic cancer ; THYROID-HORMONE ; SERUM ; ELISA ; PANCREATIC-CANCER ; CAPACITY ; DUCTAL ADENOCARCINOMA ; INTERLEUKIN-6 ; INFLAMMATORY CYTOKINES ; SCREEN ; ABILITY ; DNA-MICROARRAY ; ACUTE-PHASE RESPONSE ; ANOREXIA ; cachexia ; NEUROPEPTIDE-Y ; UNCOUPLING PROTEIN-3
    Abstract: Background and Purpose: The mechanism behind aggressive development of cachexia in patients suffering from pancreatic cancer is not well understood. In this study, we investigated which factors are associated with the cachectic status of the patients and evaluated cachexia-promoting capacity of cancer and inflammatory cells. Experimental Design: DNA microarray analysis and quantitative reverse transcription-PCR were used to screen for cachexia-associated factors in pancreatic specimens obtained from non-cachectic and cachetic patients diagnosed with pancreatic ductal adenocarcinoma. The expression pattern of the most prominently altered cachexia-associated factor, interleukin-6 (IL-6), was further analyzed in patients sera by ELISA, in pancreatic specimens by immunohistochemistry, and in a coculture system by quantitative reverse transcription-PCR using pancreatic cancer cell lines T3M4 (IL-6 positive) and Panc-1 (IL-6 negative) and peripheral blood mononuclear cells (PBMC) obtained from donors and noncachectic and cachectic patients. Results: Among numerous analyzed factors, IL-6 was significantly overexpressed in pancreatic specimens and elevated in serum of cachectic patients. The coculture system revealed that pancreatic cancer T3M4 cells but not Panc-1 cells were able to stimulate IL-6 exclusively in cachectic PBMC (by 14-fold) and this triggering was reduced by half in the presence of IL-6-neutralizing antibodies. Conclusion: IL-6 represents a prominent cachexia-associated factor in pancreatic cancer. IL-6 overexpression in cachectic patients is related to the ability of certain tumors to sensitize PBMC and induce cytokine expression in cachectic PBMC
    Type of Publication: Journal article published
    PubMed ID: 16115919
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  • 9
    Keywords: CANCER ; carcinoma ; CELL ; Germany ; liver ; PROTEIN ; PATIENT ; MECHANISM ; RAT ; CONTRAST ; mechanisms ; ACID ; ACIDS ; SIGNALING PATHWAYS ; MUSCLE ; EXCHANGE ; DEGRADATION ; SKELETAL-MUSCLE ; CANCER-PATIENTS ; AMINO-ACIDS ; CANCER PATIENTS ; PROTEASOME ; insulin ; YOUNG ; CELL CARCINOMA ; ISOLATED RAT HEPATOCYTES ; CATABOLISM ; correlation ; PROTEOLYSIS ; Male ; AUTOPHAGY ; TURNOVER ; amino acid-sensitive protein catabolism ; autophagic protein degradation ; postabsorptive protein catabolism
    Abstract: Autophagic (lysosomal) and proteasomic protein degradation are important regulatory mechanisms in the homeostasis of muscle mass, that may be profoundly disturbed in cancer and other wasting syndromes. Due to the inhibiting effect of amino acids and insulin, net proteolysis is restricted to the fasted state, and in autophagy certain amino acids have been identified as 'regulatory' in the rat, including leucine, tyrosine, phenylalanine, methionine, and histidine (i.e. LYFMH). The present cross-sectional study assessed postabsorptive net protein catabolism in male cancer patients as well as in healthy male volunteers, to analyse its relation to such 'regulatory amino acids'. Postabsorptive amino acid exchange rates across the leg were determined in patients with gastrointestinal cancer (GIC, n=47) or renal cell carcinoma (RCC, n=15), age-matched (n=33), and young male control subjects (n=42). Both groups of cancer patients revealed a significantly lower postabsorptive net protein catabolism than control subjects. Furthermore, in the control subjects, the postabsorptive net protein catabolism was found to be inversely and significantly correlated with the arterial concentrations of the 8 amino acids YSHMFGI and L which include 5 of the I regulatory amino acids'. Cancer patients, in contrast, revealed no such significant correlations. These results may indicate i) that postabsorptive net protein catabolism in skeletal muscle of healthy subjects may be sensitive to amino acids which reportedly regulate autophagy and ii) that such amino acidsensitive mechanism of protein catabolism may be disturbed in cancer patients
    Type of Publication: Journal article published
    PubMed ID: 17273753
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