View clinical trials related to Protein Metabolism.
Filter by:Rationale: Osteoarthritis (OA) of the knee is a common cause of pain and disability, especially in people over the age of 65. In the current health care system both conservative (e.g. intra-articular injections with corticosteroids) and surgical (total knee replacement, TKR) treatment are applied. Although frequently used, certain effects of these treatments on protein metabolism remain unclear. It is well known that maintenance of different tissues is determined by a dynamic balance between protein synthesis and breakdown rates, with temporary changes in either protein synthesis or breakdown allowing net protein accretion or loss. Though protein supplementation has shown to be an effective nutritional strategy in stimulating muscle protein synthesis, it remains unclear to what extent other musculoskeletal tissues are able to respond to dietary protein supplementation. Therefore, the current study assesses the impact of preoperative protein supplementation on protein synthesis in different musculoskeletal tissues of the knee. Objective: To investigate the effect of preoperative protein supplementation on Hoffa's fat pad, synovium, tendon, bone, muscle, ligament, menisci, and cartilage protein synthesis of the OA knee. Study design: Randomized, parallel (two groups) study design. The intervention group will be compared to the control group. Study population: 24 adults with OA of the knee undergoing TKR. Intervention: Daily 40 g of pre-sleep protein two weeks before TKR or no intervention. Main study parameters/endpoints: Primary study parameters include protein synthesis rates and enrichments of Hoffa's fat pad, synovium, tendon, bone, muscle, ligament, menisci, and cartilage. Secondary parameters include whole-body protein synthesis, breakdown, oxidation, and net balance. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The risks involved in participating in this study are minimal. There are no potential effects known for the ingestion of protein. Muscle biopsies and tissue collection will be performed during the surgical procedure.
Randomized cross-over design with 10 male subjects and 3 campaigns to test whether the negative effects of bed rest (6º head-down tilt) on the various systems of the body and the consequences to health of simulated weightlessness can be counteracted by the use of a defined training programme.
Mainly due to the absence of gravitational forces in weightlessness, astronauts suffer from an increased bone loss- negatively affecting health and vitality during a mission. The development of effective countermeasures to this loss includes many different aspects like sports but also nutrition. Alkaline salts, abundant in fruits and vegetables, have shown to have positive effects on markers of bone turnover of postmenopausal women but also men and younger adults. With the current study the effects of a potassium bicarbonate supplementation added to a standardised, strictly controlled, definite diet of healthy, young men, should be verified within 21 days of 6°- HDT- Bedrest- the gold standard of simulating weightlessness within earthbound conditions.
Introduction: Protein loss during critical illness is an important problem and is shown to predict overall survival. In animal studies, infusion of leucine is shown to increase the synthesis of muscle protein by 30-40% and decrease protein degradation by 30%. Objectives: Compared to saline, an amino acid or 3hydroxybutyrate infusion in the femoral artery will promote protein synthesis and inhibit breakdown assessed with local a/v phenylalanine and tyrosine tracer kinetics in healthy volunteers. These effects will include distinct alterations in muscle signal events, in particular mTOR. Methods: n = 10 healthy male subjects are equipped with catheters in aa. femorals and vv. femorals bilaterally under local anaesthetics. Each study comprises a 3-hour basal period and a 3-hour period with hyperinsulinaemic-euglycaemic clamp. During the test, samples of arterial and venous blood and 4 muscle biopsies are obtained. The intervention contain continues saline infusion compared to either amino acids (Vamin) or 3hydroxybutyrate solution FFa-3OHB. Perspectives: This study elucidates the direct effect of aminoacids and ketone bodies on muscle protein metabolism in humans and contribute to further development of nutritional therapy in human catabolic states.
A prospective, randomized and controlled study is proposed to establish whether an enteral nutrition support regimen based on pressurized whey protein and glucose improves the postoperative utilization of amino acid substrates compared to a drink based on glucose alone. The kinetics of protein metabolism (protein breakdown, protein synthesis and amino acid oxidation) will be investigated using stable isotope methodology before and after surgery in patients undergoing colon resection. Stable isotope infusions will be conducted one week before surgery and on the second postoperative day for two hours in the fasted state and for four hours while sipping the enteral nutrition support regimen. Patients will consume one of two enteral nutrition support regimens consisting of a drink containing either pressurized whey protein and glucose or glucose alone. It is hypothesized that an enteral nutrition support regimen based on pressurized whey protein and glucose promotes positive protein balance through increased protein synthesis or reduced protein breakdown compared to glucose alone.
Background: - Glucocorticoids are primary stress response hormones released from the adrenal gland when an individual is under stress. Chronic or ongoing elevation of these hormones due to prolonged stress or medical treatments can have numerous harmful effects. Researchers are interested in learning more about how these hormones affect cell growth, development, and death. To study glucocorticoid hormones, researchers plan to use the medication dexamethasone, which affects the parts of cells that respond to glucocorticoid hormones. Objectives: - To study glucocorticoid stress hormones in healthy individuals before and after receiving dexamethasone. Eligibility: - Healthy individuals at least 18 years of age. - Participants must not be using certain medications that may affect the dexamethasone test, including hormonal contraception, steroid-based drugs, and some antidepressants. Design: - This study will require an initial screening visit and a second study visit. The visits are estimated to require about 1 to 2 hours of participation over a period of up to 14 days. - Participants will be screened at visit 1 with a full physical examination and medical history, and an initial blood sample for testing. - For visit 2, participants will be asked to abstain from all food and drinks except for water for 12 hours before the appointment, and will take one tablet of dexamethasone 9 hours before the appointment. - Participants will have a second blood sample taken during visit 2, and will receive a snack after the blood is drawn.
The metabolic response to ulcerative colitis, including increased proteolysis and lipolysis and changes in energy expenditure, plays a significant role in the resulting malnutrition from which these patients suffer. Tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, has been found to be elevated in children with ulcerative colitis. TNF-alpha has been incriminated in the mechanism of weight loss in many different chronic diseases, and causes net protein and lipid catabolism. Anti-TNF-alpha antibody (infliximab) has been proven to be an effective therapy for ulcerative colitis. The purpose of this study is to determine changes in protein and lipid metabolism, as well as resting energy expenditure, before and after therapy with anti-TNF-alpha antibody (infliximab) in children with ulcerative colitis. Performing this study will better define the changes in nutrition status observed in these children following remission of active ulcerative colitis, and potentially lead to changes in medical and nutritional management of these children
Inflammatory bowel disease, which includes both Crohn's disease and ulcerative colitis, is a disease of the gastrointestinal tract leading to symptoms of abdominal pain, diarrhea, and growth disturbance. Crohn's disease is a chronic inflammatory process that may affect any part of the gastrointestinal tract, whereas ulcerative colitis is typically present only in the colon. Children with inflammatory bowel disease frequently suffer from disturbances in growth, which may continue into adulthood and result in altered growth outcomes. The metabolic response to inflammatory bowel disease, including increased protein breakdown and decreased protein synthesis may play a significant role in the resulting malnutrition and growth failure from which children with inflammatory bowel disease suffer. The purpose of this study is to compare the rates of protein synthesis within the mucosal lining of the gastrointestinal tract in children Crohn's disease or ulcerative colitis to children who have normal endoscopic examinations. By comparing children with inflammatory bowel disease to normal children, we can begin to determine how alterations in protein metabolism within the lining of the gastrointestinal tract affect whole body protein metabolism, and its consequent effects on growth. In those patients diagnosed with Crohn's disease or ulcerative colitis, a follow-up study will be conducted two weeks following the initiation of steroid therapy to determine its effects on protein metabolism. We hypothesize that children with active inflammatory bowel disease will have increased rates of protein synthesis in the lining of the gastrointestinal tract than patients who have normal endoscopy, and that increases in protein breakdown and protein synthesis will be improved following steroid therapy in children with newly diagnosed inflammatory bowel disease.
The metabolic response to Crohn's disease, including increased proteolysis and lipolysis and changes in energy expenditure, plays a significant role in the resulting malnutrition from which these patients suffer. Tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, has been found to be elevated in children with ulcerative colitis. TNF-alpha has been incriminated in the mechanism of weight loss in many different chronic diseases, and causes net protein and lipid catabolism. Anti-TNF-alpha antibody (infliximab) has been proven to be an effective therapy for ulcerative colitis. The purpose of this study is to compare changes in protein and lipid metabolism, as well as resting energy expenditure, before and after therapy with anti-TNF-alpha antibody (infliximab) or corticosteroids in children with recurrent Crohn's disease. Performing this study will better define the changes in nutrition status observed in these children following remission of active Crohn's disease, and potentially lead to changes in medical and nutritional management of these children.
Muscle catabolism is a major problem in cancer patients undergoing surgery as it negatively affects post-operative recovery. Recent evidence exists that protein metabolic changes are already apparent in cancer before muscle wasting is being present. In line, patients with breast cancer, generally characterized by a normal nutritional status, were recently found to be arginine deficient. Arginine deficiency in cancer can be explained by: 1) Reduced arginine availability, due to exhaustion of endogenous (muscle) sources of arginine 2) Enhanced arginine catabolism, due to conversion of arginine by arginase, which is abundant in tumors. Protein is the most important endogenous source of arginine. Arginine deficiency will lead to a negative feedback loop in cachexia by promoting protein breakdown in an attempt to restore plasma arginine levels. We hypothesize that pre-operative arginine supplementation in breast cancer patients diminishes the occurrence of muscle wasting after surgery by 1) normalizing arginine availability pre-operatively, resulting in conservation of protein, 2) diminishing the catabolic effects of surgery by supplying exogenous arginine for the post-operative response, 3) enhancing the anabolic capacity to feeding through supplying substrate for protein synthesis.