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  • 1
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    Karger
    Forum of Nutrition 199-200 
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    Keywords: gene expression ; HEALTH ; SIGNAL ; signal transduction ; SIGNAL-TRANSDUCTION ; EXPRESSION ; GENOME ; TRANSDUCTION ; NEW-YORK ; DISEASE ; GENE ; GENE-EXPRESSION
    Type of Publication: Book chapter
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    Keywords: GROWTH ; tumor ; Germany ; MORTALITY ; NEW-YORK ; RISK ; PROTEIN ; PATIENT ; TUMOR-NECROSIS-FACTOR ; INTERVENTION ; treatment ; PLASMA ; DECREASE ; AGE ; MUSCLE ; AMINO-ACIDS ; OXIDATIVE STRESS ; ANTIOXIDANT ; aging-related wasting ; ALPHA-LIPOIC ACID ; antioxidants and aging ; cysteine ; ELDERLY HUMANS ; INJURIOUS FALLS ; MUSCLE PROTEIN-SYNTHESIS ; muscular aging ; P70 S6 KINASE ; PLASMA REDOX STATE ; RAT SKELETAL-MUSCLE ; RESISTANCE EXERCISE ; role in aging ; tumor necrosis factor in aging
    Abstract: Aging-related loss of muscle function is a predictor of mortality and a surrogate parameter of the aging process. Its consequences include a high risk for falls, hip fractures, and loss of autonomy. Aging is associated with changes in the oxidant/antioxidant balance including a decrease in plasma thiol (cysteine) concentration. To assess the importance of cysteine, we determined in a double-blind study the effects of N-acetylcysteine on the functional capacity of frail geriatric patients and their response to physical exercise. The subjects on placebo showed only a relatively weak response, and 31% showed even a decrease in more than one parameter during the observation period. Low plasma arginine levels were correlated with a weak overall performance before exercise and a poor response to exercise. N-Acetyl-cysteine strongly enhanced the increase in knee extensor strength and significantly increased the sum of all strength parameters if adjusted for baseline arginine level as a confounding parameter. N-acetylcysteine had no significant effect on growth hormone and IGF-1 levels but caused a significant decrease in plasma TNF-alpha. These findings may provide a basis for therapeutic intervention and suggest that the loss of function involves limitations in cysteine and one or more other amino acids which may compromise muscular protein synthesis
    Type of Publication: Journal article published
    PubMed ID: 12601528
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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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    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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    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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    Keywords: AEROBIC CAPACITY, analysis, BIOPSIES, BIOPSY, BLOOD, blood volume, BLOOD-FLOW, BODIES, BODY, body we
    Abstract: PURPOSE To assess metabolism and microcirculation of healthy skeletal muscle by magnetic resonance (MR) and ultrasound techniques and to compare these data with muscle histology, and anthropometric and blood parameters. METHODS Thirty-four healthy volunteers were selected such that their measured aerobic capacity (VO(2)max) per body weight ranged between 23 and 66 mL/minute/kg to render a large variability of skeletal muscle capillarization as a result of their different physical activity. We analyzed body composition, blood parameters, and skeletal muscle fiber size and capillarization in biopsies of the vastus lateralis muscle. These data were compared with knee extensor cross-sectional area (CSA) obtained by MR imaging, microcirculation of the vastus lateralis muscle by contrast-enhanced ultrasound (CEUS), and its energy and lipid metabolism measured with P-31 and H-1 MR spectroscopy. Statistical analysis was performed using Pearson's correlation coefficient and significance was tested at a level of .5%. RESULTS The variable physical activity was reflected in a large variability of vastus lateralis muscle perfusion and metabolism at rest with highest histologic capillarization and CEUS-perfusion values observed in the best-trained volunteers. Levels of high-energy phosphates, such as phosphocreatine, were positively correlated with CSA (r = .5) and histologic fiber size (r = .6 for type IIA and IIX fibers), while phosphocreatine concentration was significantly negatively correlated to myocellular lipids (r = -.6) and trimethyl ammonium containing compounds (r = -.8). Local blood volume measured in vivo with CEUS was positively correlated with several histologic capillarization parameters. CONCLUSIONS Dedicated MR- and CEUS-methods deliver (patho-)physiologic information about capillarization and fiber characteristics of skeletal muscles in vivo and hence establish a useful diagnostic tool for muscular diseases
    Type of Publication: Journal article published
    PubMed ID: 17894621
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    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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