Feeding Methionine Research Articles

Metabolic responses of folic acid and related compounds to thyroxine in rats.

This study deals with the effects of thyroidectomy and feeding thyroid powder on histidine and folic acid metabolism. Normal rats maintained on a soy protein diet, low in methionine but supplemented with vitamin B-12, oxidize approx. 10% of an injected dose of [2-14C]histidine in 3 h and excrete low levels of formiminoglutamic acid. Addition of methionine increases histidine oxidation to approx. 20%. The feeding of thyroid powder or the injection of high levels of thyroxine decreases histidine oxidation and increases formiminoglutamic acid excretion. Surgical thyroidectomy at weaning increases histidine oxidation to approx. 45% and, thus, resembles the effect of methionine in promoting histidine oxidation and decreasing formiminoglutamic acid excretion. The feeding of methionine to the thyroidectomized animal further increases histidine oxidation to 65%. The distribution of folate forms in the liver was determined by column chromatography following administration of a dose of tritiated folic acid. In the normal animal, tetrahydrofolate accounts for 38% of the total folate present. The feeding of methionine increases this to 48%, which is consistent with the observed increase in histidine metabolism. Thyroidectomy increases the percentage of tetrahydrofolate to 63% and the feeding of methionine further increases it to 68%. The percentage of tetrahydrofolate relative to total folate is in proportion to the observed rate of histidine metabolism. The action of thyroidectomy in increasing histidine oxidation may be accounted for by its effect in increasing the proportion of tetrahydrofolate.

Stimulation of erythropoietin secretion by single amino acids.

SummaryProtein deficiency in rats results in decreased ability to produce erythropoietin after hypoxic stimulation. This defect can be reversed by a single protein feeding at the time of exposure to hypoxia. The present experiments show that feeding of methionine, leucine or cystine also corrected the defect in erythropoietin production. These amino acids may serve to signal the adequacy of protein reserves and permit the synthesis of erythropoietin. Other single amino acids had minimal or no effect.Study has been supported by University of Illinois BRSG 7612, Veterans Administration Research Funds, funds from the American Cancer Society, Illinois Division, Leukemia Research Foundation and the Hematology Research Foundation. The authors wish to thank Mrs. Jan Rone for her technical assistance.

Factors affecting the urinary excretion of endogenously formed dimethyltryptamine in normal human subjects.

The hallucinogenic substance N',N'-dimethyltryptamine and its precursor N-methyltryptamine were found in 24-h specimens of urine from 19 normal human subjects; the mean excretion rates were 386 ng 24 h(-1) and 856 ng 24 h(-1) respectively. The urinary excretion of both compounds was unrelated to age, sex, urinary volume, or creatinine, nor was any consistent diurnal pattern observed. Rates for the mono and dimethylated compounds were not correlated. Diet and the intestinal flora were excluded as a source of urinary dimethyltryptamine. Administration to 4 subjects of sufficient ammonium chloride to increase the H ion concentration of the urine caused a transient increase in dimethyltryptamine excretion but no consistent increase in the rate for N-methyltryptamine. Acidification of the urine did not appear to be the determining factor in this result since in one subject the same drop in urinary pH was achieved by feeding methionine without any increase in dimethyltryptamine excretion.

Feeding Encapsulated Methionine Supplement to Lactating Cows , ,

Twenty lactating Holstein cows were fed individually and were randomly assigned to 4 treatment groups in a continuous 120-day trial. The study was to determine the effects of methionine supplementation at 12g per day and of feeding methionine supplement more frequently than twice daily. Treatment 2× was twice daily feeding; 2×M, twice daily feeding plus methionine; 4× was 4 feedings daily, and 4×M was 4 feedings daily plus methionine. Average daily fat-corrected milk production, milk fat, milk protein, and ration intake by treatments were: 2×) 19.21kg, 3.49%, 3.56%, 16.42kg; 2×M) 18.22kg, 3.72% 3.49%, 15.59kg; 4×) 17.56kg, 3.60%, 3.41%, 15.11kg; and 4×M) 17.37kg, 3.43%, 3.47%, 13.88kg. Analysis of covariance indicated no significant differences (P<.05) for daily fat-corrected milk production, milk composition, and feed intake. No significant differences were found in urinary urea nitrogen, urine volume, urinary nitrogen, creatinine, urinary amino acids, or blood ammonia. The 4× group had higher blood urea nitrogen values than other groups. The 4× and 4×M groups appeared to have lower methionine to valine ratios than the 2× and 2×M groups at the end of the trial. Feeding encapsulated methionine at 12g per day showed no benefit for increasing fat-corrected milk production.

Mercaptans and dimethyl sulfide in the breath of patients with cirrhosis of the liver. Effect of feeding methionine.

Abstract Mercaptans have been measured in the breath for the first time. The only sulfur compounds detected in the breath of cirrhotic patients in hepatic coma or cirrhotic patients fed methionine were methanethiol, ethanethiol, and dimethyl sulfide. Normally, methanethiol is 6 to 20 per cent of the mercaptans excreted. Under fasting conditions in the absence of gastrointestinal bleeding, methane- and ethanethiol are approximately twice normal in severe decompensated cirrhosis. In the presence of gastro-intestinal bleeding, methanethiol increases further severalfold. After ingestion of methionine, the mercaptans are approximately doubled in the breath of normal persons but not in cirrhotic patients. The pungent odor of dimethyl sulfide appears in the breath of the cirrhotic patients, and the intensity of the odor is directly related to the amount of dimethyl sulfide in the breath.

Effect of Vitamin E, Arginine and Methionine on Free Amino Acids and Lipids in Selected Rat Tissues

The effect of dietary arginine, methionine and vitamin E on selected free amino acids in plasma and on lipids in liver was investigated. Weanling male rats were fed a vitamin E-deficient ration supplemented with methionine, arginine or methionine plus arginine with and without vitamin E. Supplementary feeding of arginine, methionine or a combination of these amino acids increased in plasma the concentration of the supplementary amino acid. The effect of vitamin E deficiency on growth had become apparent only in animals fed added arginine or methionine. Vitamin E had no effect on the concentration of arginine, methionine or tyrosine in plasma. Feeding of supplementary methionine or tocopherol decreased the concentration of cholesterol in liver. Vitamin E decreased the amount of total lipids in liver of all animals. The data suggest that a marked change in the proportion of arginine and methionine in plasma may accelerate the development of vitamin E deficiency in the rat.

BLOOD CORTICOSTERONE LEVELS IN THE RAT AFTER ADMINISTRATION OF AMINO ACIDS.

Munro and Mukerji1 observed that the feeding of single large doses of certain individual amino-acids, notably glycine, methionine and leucine, caused a marked stimulation of uptake of phosphorus-32 by rat-liver ribonucleic acid (RNA) during the next 18 h. In the case of methionine and leucine, but not of glycine, this action was abolished by adrenalectomy2. It was therefore proposed that the increased incorporation of phosphorus-32 into liver RNA after feeding methionine or leucine was due to release of adrenocortical hormones, which are known to induce changes in liver RNA metabolism3. The experiments reported here show that, within a 24-h period of administering methionine or leucine to rats, there is an elevation of blood corticosterone-level. Administration of other amino-acids or of casein does not have this effect. These observations would thus appear to confirm the proposed mechanism of action of methionine and leucine on liver RNA metabolism.

Effect of DL-ethionine and S-ethyl-L-cysteine on rat liver regeneration.

The administration of diets containing 0.05–0.40% dl-ethionine to partially hepatectomized rats decreases the extent of liver regeneration over a period of 10.5 days. Body weight losses and definite liver pathology are noted for animals of either sex fed the rations with 0.30% or 0.40% ethionine. The effect is neutralized by the simultaneous feeding of methionine but not by choline, thereby reflecting definite amino acid antagonism. S-ethyl-l-cysteine, a homolog of ethionine, at a dietary level of 0.40% is without effect on the rate of liver regeneration.

Cystathionine in the liver following the feeding of methionine and serine

Cystathionine has been identified by paper chromatography as a constituent of the liver following the feeding of both l-methionine and l-serine to a fasting rat. l-Methionine alone was ineffective.

Influence of Methionine and Thiouracil on Nitrogen Balance Index and Organ Weights of Adult Rat.

SummaryThe addition of methionine and of thiouracil to the diet of rats altered the nitrogen balance index in proportion to the level of the compound in the diet. Although both methionine in high concentration and thiouracil caused a decrease in body weight and a reduction in nitrogen balance index, the compounds increased the total liver nitrogen; however, methionine increased the nitrogen per gram of tissue without affecting the size of the organ while thiouracil increased the size of the organ without affecting the nitrogen per gram of tissue. Both methionine and thiouracil increased the size of the thyroid, while methionine alone increased the size of the kidney. Both compounds increased the total plasma proteins by increasing the plasma globulin. Both methionine and thiouracil decreased creatine excretion; however, the effect of thiouracil is marked in comparison to methionine. These data indicate that the result of feeding methionine or thiouracil is very similar in end result but that the mechanism...

An Attempt to Shorten the Molt and to Stimulate Egg Production by the Feeding of Methionine

It has been found in this laboratory (Holman, 1941) that when egg production exceeds 50 percent, or when the daily feather loss during the molt exceeds 0.9 gm., hens fed a practical poultry ration are usually in negative sulfur balance. Since methionine is a constituent of egg albumin and since it is an essential amino acid for the growing chick (Klose and Almquist, 1941), although its essentiality for the hen is not known, it is conceivable that heavy layers are forced to draw upon their body supply of this amino acid for egg formation. Such a withdrawal might disturb the physiological status of the hen and be one of the causes of high mortality commonly observed in laying flocks. Furthermore, it was considered possible that an increase in the methionine consumed might furnish a constituent necessary for feather formation and thus shorten the molt.Consequently on the assumption that the .

THE OXIDATION OF THE SULFUR OF HOMOCYSTINE, METHIONINE, AND S-METHYLCYSTEINE IN THE ANIMAL BODY

Since it had been found that homocystine could support growth on a cystine-deficient diet in lieu of cystine (l), the oxidative fate of the sulfur of this compound was of interest to us. Furthermore, the possible relationship of this compound to the intermediary metabolism of methionine made such a study desirable. The surprising observation that the feeding of methionine to rats on a cystine-deficient diet results in a marked stimulation of growth was first made by Jackson and Block (2) and has been verified in other laboratories (3, 1). As pointed out by Butz and du Vigneaud (4), one might expect that homocystine would likewise support growth under these conditions if in the metabolism of methionine demethylation took place. The study of the substitution in the diet of methionine and cystine by homocystine was therefore undertaken with the results mentioned above (I), which we feel are in harmony with the idea just expressed in regard to the intermediary metabolism of methionine. It should be recalled that the lack of the growth-promoting powers of other disulfide acids such as @-dithiodipropionic, dithiodiglycolic, and a-dihydroxy-&dithiodipropionic acids has already been shown by Westerman and Rose (5), and therefore the behavior of the disulfide amino acid, homocystine, is all the more significant. The same view-point of the metabolism of methionine on the basis of evidence of an even more direct nature was independently arrived at by Virtue and Lewis (6, 7). These investigators made the interesting observation that after the feeding of methionine to rats and rabbits a positive test for the disulfide linkage was obtained