Methionine Levels (methionine + level)

Distribution by Scientific Domains


Selected Abstracts


Dietary amino acids fed in free form and as protein components do not differently affect postprandial plasma insulin, glucagon, growth hormone and corticosterone responses in rats

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 7-8 2006
J. A. Nolles
Summary This study examined, whether the postprandial fate of dietary amino acids from different amino acid sources is regulated by the responses of insulin, glucagon, corticosterone and growth hormone (GH). Male Wistar rats were cannulated in the vena jugularis and assigned to dietary groups. The diets contained 21% casein or the same amino acids in free form. In the free amino acid diets, methionine level was varied between the groups. The feed was supplied in two distinct meals. In previous experiments it was established that oxidative amino acid losses of the free amino acid diets and protein diets were different. After 3 weeks on those diets, it appeared that the differences in postprandial oxidative losses had been diminished. GH was measured every 12 min, from 144 min before the start of the experimental meal over the following 144 min. Insulin and corticosterone were measured six times from the start of the meal until 270 min after the meal. No differences have been observed between the hormonal responses to both meals at day 5 and at day 26. In conclusion, it has been found that the differences in the oxidative losses between protein and free amino acid meals are not mediated by the combined action of the insulin, glucagon, corticosterone and GH. Postprandial catabolism of amino acids is most probably regulated by substrate induction. [source]


Dietary amino acids fed in free form or as protein do differently affect amino acid absorption in a rat everted sac model

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2008
J. A. Nolles
Summary In the present study, the effect of free amino acid (FAA) diets on the intestinal absorption rate of methionine and leucine was studied ,ex vivo' with rats adapted for different periods of time to the diets, using the everted sac method. The adaptation period to the 21% FAA diet with an amino acid content based on casein was either, 0 (no adaptation, N-ADA), 5 (short-term adaptation, ST-ADA), or 26,33 days (long-term adaptation, LT-ADA). Within the ST-ADA and the LT-ADA groups, three different levels of methionine were included: 50%, 100% and 200% of the level normally present in casein. All diets were iso-nitrogenous and iso-caloric. After the adaptation period (0, 5, or 26,33 days), intestinal everted sacs were prepared. Methionine or leucine was added to the medium as transport substrate. The methionine absorption rate of the rats of the LT-ADA groups was higher than that of the N-ADA groups. Furthermore, adaptation to 200% dietary methionine levels caused a significantly slower leucine absorption compared to the 100%, and 50% group. Methionine absorption was similar in the 100% and 200% groups, but the absorption of methionine in the 50% group was enhanced in the distal part of the intestines. We concluded that in response diets with 21% FAAs as only amino acid source, amino acid absorption is decreased to avoid toxic effects of high levels of methionine in the circulation. [source]


Dysregulated Cytokine Metabolism, Altered Hepatic Methionine Metabolism and Proteasome Dysfunction in Alcoholic Liver Disease

ALCOHOLISM, Issue 2005
Craig McClain
Abstract: Alcoholic liver disease (ALD) remains an important complication and cause of morbidity and mortality from alcohol abuse. Major developments in our understanding of the mechanisms of ALD over the past decade are now being translated into new forms of therapy for this disease process which currently has no FDA approved treatment. Cytokines are low molecular weight mediators of cellular communication, and the pro-inflammatory cytokine tumor necrosis factor (TNF) has been shown to play a pivotal role in the development of experimental ALD. Similarly, TNF levels are elevated in the serum of alcoholic hepatitis patients. Abnormal methionine metabolism is well documented in patients with ALD, with patients having elevated serum methionine levels, but low S-adenosylmethionine levels in the liver. On the other hand, S-adenosylhomocysteine and homocysteine levels are elevated in ALD. Recent studies have documented potential interactions between homocysteine and S-adenosylhomocysteine with TNF in the development of ALD. Altered proteasome function also is now well documented in ALD, and decreased proteasome function can cause hepatocyte apoptosis. Recently it has been shown that decreased proteasome function can also act synergistically to enhance TNF hepatotoxicity. Hepatocytes dying of proteasome dysfunction release pro-inflammatory cytokines such as Interleukin-8 to cause sustained inflammation. This article reviews the interactions of cytokines, altered methionine metabolism, and proteasome dysfunction in the development of ALD. [source]


Progressive cerebral edema associated with high methionine levels and betaine therapy in a patient with cystathionine ,-synthase (CBS) deficiency

AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 1 2002
Reza Yaghmai
Abstract Cystathionine ,-synthase (CBS) deficiency, the most common form of homocystinuria, is an autosomal recessive inborn error of homocysteine metabolism. Treatment of B6-nonresponsive patients centers on lowering homocysteine and its disulfide derivatives (tHcy) by adherence to a methionine-restricted diet. However, lifelong dietary control is difficult. Betaine supplementation is used extensively in CBS-deficient patients to lower plasma tHcy. With betaine therapy, methionine levels increase over baseline, but usually remain below 1,500 ,mol/L, and these levels have not been associated with adverse affects. We report a child with B6-nonresponsive CBS deficiency and dietary noncompliance whose methionine levels reached 3,000 ,mol/L on betaine, and who subsequently developed massive cerebral edema without evidence of thrombosis. We investigated the etiology by determining methionine and betaine metabolites in our patient, and several possible mechanisms for her unusual response to betaine are discussed. We conclude that the cerebral edema was most likely precipitated by the betaine therapy, although the exact mechanism is uncertain. This case cautions physicians to monitor methionine levels in CBS-deficient patients on betaine and to consider betaine as an adjunct, not an alternative, to dietary control. © 2002 Wiley-Liss, Inc. [source]


Effect of methionine on intestinal enzymes activities, microflora and humoral immune of juvenile Jian carp (cyprinus carpio var. Jian)

AQUACULTURE NUTRITION, Issue 5 2009
L. TANG
Abstract An 8-week feeding experiment was conducted to determine the effect of dietary methionine supplementation on intestinal microflora and humoral immune of juvenile Jian carp (initial weight of 9.9 ± 0.0 g) reared in indoor flow-through and aerated aquaria. Eight amino acid test diets (350 g kg,1 crude protein, CP), using fish meal, soybean-condensed protein and gelatin as intact protein sources supplemented with crystalline amino acids, were formulated to contain graded levels of methionine (0.6,22.0%) at a constant dietary cystine level of 3 g kg,1. Each diet was randomly assigned to three aquaria. Growth performance and feed utilization were significantly influenced by the dietary methionine levels (P < 0.05). Maximum weight gain, feed intake occurred at 12 g kg,1 dietary methionine (P < 0.05). Methionine supplementation improved hepatopancreas and intestine weight, hepatosomatic and intestine index, intestinal ,-glutamyltransferase and creatine kinase activity, Lactobacillus count, Bacillus count, lysozyme activities, lectin potency, sim-immunoglobulin M content, addiment C3,C4 contents and serum total iron-binding capacity and declined Escherichia coli and Aeromonas counts. Quadratic regression analysis of weight gain against dietary methionine levels indicated that the optimal dietary methionine requirement for maximum growth of juvenile Jian carp is 12 g kg,1 of the dry diet in the presence of 3 g kg,1 cystine. [source]


Re-evaluation of total sulphur amino acid requirement and determination of replacement value of cystine for methionine in semi-purified diets of juvenile Nile tilapia, Oreochromis niloticus

AQUACULTURE NUTRITION, Issue 3 2009
T.N. NGUYEN
Abstract Two feeding experiments were conducted to re-evaluate the total sulphur amino acid (TSAA; methionine and cystine) requirement and determine the replacement value of cystine for methionine of juvenile Nile tilapia (Oreochromis niloticus). Semi-purified diets used in both experiments contained 3510 kcal gross energy and 280 g of protein per kilogram diet from casein, gelatin and crystalline amino acids. The basal diet of the first experiment contained 3.1 g methionine and 0.4 g cystine per kilogram. l -methionine was added to the seven remaining diets at 1.0 g kg,1 increment to produce methionine levels ranging from 3.1 to 10.1 g kg,1 diet. Each diet was fed to four replicate groups of juvenile Nile tilapia (1.28 g mean weight) in a recirculation system for 8 weeks. Broken-line regression analysis of weight gain data indicated that the TSAA requirement of juvenile Nile tilapia was 8.5 g kg,1 of the diet or 30.4 g kg,1 of dietary protein. In the second experiment, TSAA level was set at 95% of the requirement value determined in the first experiment. Seven diets were made with different ratios of l -methionine and l -cystine (20 : 80, 30 : 70, 40 : 60, 50 : 50, 60 : 40, 70 : 30 and 80 : 20, based on an equimolar sulphur basis). Each diet was also fed to four replicate groups of juvenile Nile tilapia (4.14 g mean weight) in a recirculation system for 8 weeks. Regression analysis of weight gain data using broken-line model indicated that cystine (on a molar sulphur basis) could replace up to 49% of methionine requirement in semi-purified diets for juvenile Nile tilapia. [source]