Browsing by Subject "Proteins -- Physiological effect."
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Item Effects of 28 days of protein and amino acid supplementation and ankle immobilization on gastrocnemius muscle mass and strength and atrophy- and apoptosis-related gene expression in males.(2008-06-11T11:43:18Z) Wismann, Jennifer.; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Purpose: The primary purpose was to determine the extent to which the daily supplementation of protein and amino acids for 28-days in combination with ankle immobilization in humans attenuated decreases in: 1) gastrocnemius muscle mass, 2) plantar flexion strength, 3) and expression of genes associated with the ubiquitin proteolytic pathway (UPS) and calcium-activated proteolytic system (CAS). A secondary purpose was to assess the safety of 28-days of protein and amino acid ingestion by evaluating whole blood and serum clinical chemistry markers. Methods: Twenty male participants wore a lower-limb immobilization boot for 28 days, consumed either a protein and amino acid supplement or an isocaloric carbohydrate placebo twice daily, and underwent testing at days 0, 14, and 28. Each testing session included hemodynamic measurements, blood collection, body composition analysis, lower leg girth and skinfold measurement, strength measurement, dietary analysis, and gastrocnemius muscle biopsies. The muscle tissue was analyzed for mRNA expression of ubiquitin, 20S-HC2, 20S-HC3, E2, E3, atrogin-1, MuRF1, calpain 1, calpain 2, myostatin, TNF-α, and NF-κB. Results: Lower-leg girth decreased over time (p = 0.020), and increased the expression of several genetic variables, but there were no significant changes in the body composition or strength variables (p > 0.05). All UPS, CAS, cytokine, and myostatin degenerative markers showed a significant increase over time (p < 0.05). However, significant interactions only occurred for E2 (time x group, p < 0.001) and E3 (time x group x leg, p > 0.016). Conclusion: The study showed no difference between groups for any of the genetic proeolytic markers, but indicated that several of these markers were increased in the immobilized and control legs. These changes may indicate a link between the UPS and TNF-α and NF-κB. Additionally, the results also indicated that myosatin may play a role in muscle astrophy induced by immobilization, instead of only disease and fasting.Item Effects of four weeks of daily soy or dairy milk ingestion on the exercise-induced proteolytic responses in plasma and skeletal muscle in a post-menopausal female population.(2009-08-25T16:30:08Z) Serra, Monica Christine.; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Sarcopenia is defined as a loss of muscle mass and muscle strength associated with aging. Changes in muscle function can occur as early as the fourth decade of life. Evidence indicates that the calpain and ubiquitin proteolytic degradation pathways account for the majority of myofibrillar protein degradation seen with muscle atrophy. The purpose of this study was to investigate the effects of daily consumption of soy or dairy milk in older females on systemic plasma and local skeletal muscle markers of muscle proteolysis before and after a single bout of eccentric exercise. Thirty one female participants consumed three servings per day of either soy or dairy milk for four weeks, followed by a 45 minute downhill run. Testing sessions were complete pre and post supplementation, as well as at 0, 4, 24, and 48 hrs post exercise. Each testing session included blood collection and vastus lateralis muscle biopsy, except no biopsy was performed immediately or 48 hrs post exercise. The blood was analyzed for plasma creatine kinase and the muscle tissue for mRNA expression of ubiquitin, E2, E3, atrogin-1, muRF1, calpain 1, and calpain 2. Although no significant group x time interactions were observed, a significant time effect was observed for plasma CK (p<0.0001) and muscle mRNA expression of E3 (p=0.04), atrogin-1 (p=0.02), and calpain 2 (p=0.04). Further, evaluation revealed that these differences resulted after the acute exercise bout. The results of this study showed that soy milk ingestion was not influential in attenuating the expression of the ubiquitin and calpain proteolytic pathways compared to dairy milk; however, the eccentric exercise bout was effective at altering expression of markers within both pathways. Future studies should address potential confounding dietary factors by utilizing an inert control group to determine if both soy and dairy milk could be protective with regard to exercise induced proteolysis.