Body Amino Acid Metabolism Research Articles

Revealing Interactions of Gut Microbiota and Metabolite in Confined Environments Using High-Throughput Sequencing and Metabolomic Analysis.

A confined environment is a special kind of extreme working environment, and prolonged exposure to it tends to increase psychological stress and trigger rhythmic disorders, emotional abnormalities and other phenomena, thus seriously affecting work efficiency. However, the mechanisms through which confined environments affect human health remain unclear. Therefore, this study simulates a strictly controlled confined environment and employs integrative multi-omics techniques to analyze the alterations in gut microbiota and metabolites of workers under such conditions. The aim is to identify metabolic biomarkers and elucidate the relationship between gut microbiota and metabolites. High-throughput sequencing results showed that a confined environment significantly affects gut microbial composition and clusters subjects' gut microbiota into two enterotypes (Bla and Bi). Differences in abundance of genera Bifidobacterium, Collinsella, Ruminococcus_gnavus_group, Faecalibacterium, Bacteroides, Prevotella and Succinivibronaceae UCG-002 were significant. Untarget metabolomics analyses showed that the confined environment resulted in significant alterations in intestinal metabolites and increased the activity of the body's amino acid metabolism and bile acid metabolism pathways. Among the metabolites that differed after confined environment living, four metabolites such as uric acid and beta-PHENYL-gamma-aminobutyric acid may be potential biomarkers. Further correlation analysis demonstrated a strong association between the composition of the subjects' gut microbiota and these four biomarkers. This study provides valuable reference data for improving the health status of workers in confined environments and facilitates the subsequent proposal of targeted prevention and treatment strategies.

Abstract PL04-03: Evidence for increased muscle breakdown associated with early pancreatic cancer

Abstract Most patients with pancreatic ductal adenocarcinoma (PDAC) are diagnosed with advanced disease and survive less than 12 months. PDAC has been linked with obesity and glucose intolerance, but whether changes in circulating metabolites are associated with early cancer progression had not been studied. To better understand metabolic derangements associated with early disease, we profiled metabolites in prediagnostic plasma from pancreatic cancer cases and matched controls from four prospective cohort studies. We found that elevated plasma levels of branched chain amino acids (BCAAs) are associated with a greater than 2–fold increased risk of future pancreatic cancer diagnosis. This elevated risk was independent of known predisposing factors, with the strongest association observed among subjects with samples collected 2 to 5 years prior to diagnosis when occult disease is likely present. Utilizing genetically engineered mouse models of PDAC, we have confirmed that these elevations represent a marker of early, sub-clinical disease. Furthermore, using these model systems, we demonstrate that the increase in plasma BCAAs reflects a breakdown of tissue protein that accompanies early stage disease. Together, these findings suggest that altered whole body amino acid metabolism is an early event in development of PDAC, and that elevations in BCAAs can be seen in patients years before their pancreatic cancer diagnosis. Citation Format: Matthew G. Vander Heiden. Evidence for increased muscle breakdown associated with early pancreatic cancer. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr PL04-03.

Immunonutrition

To outline recent findings on the efficacy of immunonutrients in patients undergoing inflammatory stress due to surgery, infection and cancer. Enteral nutrition is more efficacious and poses lower risks than parenteral nutrition. It reduces infection rates and shortens ICU and hospital length of stay of critically ill patients. Beneficial effects of immunonutrition are most apparent in malnourished patients. Perioperative enteral nutrition is more effective than postoperative nutrition. In Crohn disease similar remission rates are achieved with enteral nutrition as with steroids. Glutamine, omega-3 fatty acids and antioxidants exert beneficial influences in diverse patient populations. L-arginine is an important immunonutrient having both beneficial and adverse effects. The former effect occurs in necrotizing enterocolitis; the latter influence is seen in septic patients. The gut plays a major role in whole body amino acid metabolism, particularly arginine homeostasis. Arginase and nitric oxide synthetase compete for arginine within immune cells and play a pivotal role in clinical outcome during infection. In cancer a range of antioxidants are able to ameliorate immunosuppression. Intravenous lipids may be deleterious due to the pro-inflammatory effects of omega-6 fatty acids. Omega-3 fatty acids are anti-inflammatory and combined with medium chain triglyceride (MCT) and olive oil may provide a more efficacious form of intravenous lipid. Immunonutrition is effective in improving outcome in a wide range of patients when applied enterally, particularly in malnourished individuals. Parenteral immunonutrition carries a higher risk but can be efficacious in selected patient groups for whom enteral nutrition is problematic.

Dynamics of human whole body amino acid metabolism: use of stable isotope probes and relevance to nutritional requirements.

Dynamics of human whole body amino acid metabolism: use of stable isotope probes and relevance to nutritional requirements.

Protein turnover in skeletal muscle of piglets.

1. Rates of protein synthesis and catabolism were measured in longissimus dorsi and hind-limb muscles of suckling piglets.2. Half-lives for synthesis and catabolism for mixed sarcoplasmic proteins were 4.8 and 9.4 d respectively. The corresponding values for mixed myofibrillar proteins were 5.7 and 16.4 d.3. The half-lives for synthesis of sarcoplasmic proteins were significantly different from those of myofibrillar proteins and were not confounded by contamination of the sarcoplasmic protein fraction with plasma proteins of higher specific activity.4. Individual myofibrillar proteins were synthesized and catabolized at rates which were not statistically significantly different. Intramuscular connective tissue also appeared to turnover rapidly, the half-life for synthesis being 8 d and that for catabolism 20 d.5. Values obtained for the specific radioactivities of aspartate + glutamate in mixed plasma proteins support the view that, in so far as the young of animals larger in mature body size than rats or mice are concerned, muscle assumes a more important role relative to liver in regulating whole body amino acid metabolism.