Lawrence V. Hankes

Incorporation of C14-labeled amino acids by Trichinella spiralis larvae.

Abstract 1. 1. Carbon-14-labeled amino acids were fed to mice infected with Trichinella spiralis to test the ability of immature larvae and encysted larvae to incorporate C 14 from the host. The C 14 amino acids were fed beginning 14, 56, or 180 days after infection. 2. 2. Immature larvae (14 days) incorporated higher levels of C 14 activity (C 14 per gram of dry tissue) from glycine-2-C-14 and dl -alanine-2-C-14 than the amounts found in muscle tissue. 3. 3. When the 7-day period of C 14 feeding began 56 days after infection, the encysted larvae incorporated C 14 activity indicating that the larvae were exchanging metabolites with the host. The specific activity of the carbon in the larvae exceeded that found in the muscles of the host. 4. 4. The presence of encysted Trichinella larvae in the muscle of 56-day and 180-day infected mice did not alter the incorporation of C 14 activity into muscle protein when compared with noninfected muscle. 5. 5. The encysted larvae in the 180-day infected mice incorporated significant levels of C 14 activity from the tissues of mice fed glycine-1-C-14 and dl -alanine-1-C-14 diets showing an active metabolism by well-encapsulated Trichinella spiralis larvae.

Incorporation of DL-tyrosine-2-C-14 and DL-tryptophan-2-C-14 by encysted Trichinella spiralis larvae.

1. 1. Trichinella spiralis larvae incorporated significant levels of C14 activity when dl-tyrosine-2-C-14 and dl-tryptophan-2-C-14 labeled diets were fed to mice with infections of 56 and 180 days duration. 2. 2. In the 6-month-old infections the well-developed cyst wall surrounding the larvae retains sufficient permeability to tyrosine and tryptophan or to products of metabolism of these amino acids by the host. 3. 3. The larvae from the 62 and 186-day infected mice that were fed a dl-tyrosine-2-C-14 diet incorporated 86 and 92% of their total C14 content into protein (defined as material precipitable by tungstic acid). 4. 4. When the dl-tryptophan-2-C-14 diet was fed, the 62 and 186-day-old larvae incorporated 86 and 85% of their total C14 content into larval protein. 5. 5. Incorporation of total C14 into muscle protein was reduced in 186-day infected mice fed dl-tyrosine-2-C-14 as compared to muscle proteins obtained from noninfected animals. 6. 6. With the dl-tryptophan-2-C-14 diet, a 10-fold increase in C14 activity was found in 186-day infected muscle protein over that observed in noninfected muscle. This may indicate a significant change in tryptophan metabolism of the host during the course of a Trichinella infection in mice.

In vitro metabolism of DL-tyrosine-2-C-14 and DL-tryptophan-2-C-14 by Trichinella spiralis larvae.

Abstract 1. 1. Trichinella spiralis larvae incorporated C14 when maintained in vitro in a serum-Krebs-Ringer medium containing either dl -tyrosine-2-C-14 or dl -tryptophan-2-C-14. Incorporation of C14 from labeled tryptophan was also observed in Krebs-Ringer medium without serum. 2. 2. Uptake of the C14-labeled amino acids was progressive through 3-to 48-hour periods of incubation. 3. 3. The larvae incorporated somewhat more C14 activity (cpm/mg carbon) from the dl -tryptophan-2-C-14 media than from the dl -tyrosine-2-C-14 medium. 4. 4. Of the total C14 taken up by the larvae cultured for 24 hours in the labeled-tyrosine-medium, 43% of the C14 was incorporated into proteins (defined as material precipitable by tungstic acid). 5. 5. With dl -tryptophan-2-C-14 labeled media the larvae incorporated 35% of their total C14 into protein when serum was present. In the serum-free medium the larvae incorporated 54% of their total C14 into protein material.

In vitro Metabolism of DL-AIanine-2-C-14 and Glycine-2-G-14 by Trichinella spiralis Larvae.

Summary 1. Trichinella spiralis larvae incorporated C14 when cultured in vitro in a serum-Rrebs-Ringer medium or Rrebs-Ringer medium containing either dl-alanine-2-C-14 or glycine-2-C-14. 2. Carbon-14 analysis of the larvae revealed a progressive uptake of the C14-labeled amino acids in both types of media through 48 hours of incubation. 3. The larvae incorporated more C14 activity (cpm) from glycine-2-C-14-labeled media than from dl-alanine-2-C-14-labeled media. 4. Of the total C14 incorporated by larvae cultured 48 hours in glycine-2-C-14-la-beled media about 70 to 84% was precipitable by tungstic acid, and was presumably chiefly in the proteins. Larvae cultured in the dl-alanine-2-C-14-labeled media incorporated about 32-57% of their total C14 content into material precipitable by tungstic acid.

Synthesis and Metabolism of Quinolinic Acid Ring Labeled with Tritium.

Summary 1. Quinolinic acid was labeled in the 4, 5, and 6 positions with tritium by the neutron recoil method. 2. Intraperitoneal injection of labeled quinolinic acid into rats was followed by excretion of labeled N1 methylnicotinamide in urine during the next 24 hours. Tritium contents of excreted N1 methylnicotinamide in 2 experiments indicated that 7.6 and 23.6% originated from the injected labeled quinolinic acid. The evidence is definite that quinolinic acid can serve in the rat as a source of niacin. 3. Most of the injected quinolinic acid was exreted as such in the urine. Quinolinic acid isolated from urines of 2 rats had specific activities of 103 and 112% of injected quinolinic acid. The increase in specific activity suggests that tritium-labeled quinolinic acid may have been less rapidly metabolized than the unlabeled substance.

The uptake of 14C-labeled hydroxyanthranilic acid and enantiomers of tryptophan, kynurenine, and hydroxykynurenine in human blood.

Summary Labeled enantiomers of tryptophan, kynurenine, and hydroxykynurenine were given to five patients with scleroderma. Blood samples were drawn periodically over a 24-hr period. When the d-isomers were given, peak blood levels of radioactivity did not appear until 8 hr, whereas with the natural l-isomers peak levels were reached in 2 hr Considerable radioactivity was found firmly bound to the precipitated plasma proteins from both the l- and d-isomers. Incubation studies confirmed the binding of the d-isomers to the serum proteins. These experiments show that the use of pure labeled l-isomers is required, when studying the metabolism of amino acids in man, and that compounds other than l-tryptophan are bound to serum proteins in significant quantities. We wish to thank first the patients who volunteered to participate in the study and secondly John Jessep, M.D., for his excellent care of the patients.

O-Aminophenol A Urinary Product of Tryptophan Metabolism in the Human.

Summary The metabolic fate of DL-Tryptophan-7a-C14 in a human with multiple myeloma was studied. Only 5% of the administered C14 was excreted as respired C14O2 and 14% in the urine in the first 24 hours. O-aminophenol-2-C14 was isolated from the urine.

Effect of Trichinella spiralis infection on incorporation of amino acids into serum and hemoglobin

Abstract An alteration of metabolism of C14-labeled amino acids into serum and hemoglobin was observed when glycine, alanine, tyrosine, and tryptophan were fed to Trichinella-infected mice. An initial fall in serum C14 specific activity and subsequent rise was observed as duration of the infection was extended from 14 to 180 days. The observed changes in concentration of C14 in serum and hemoglobin appear to be related to the influence of the infection on various amino acid transaminase and decarboxylase enzyme systems. dl -Tryptophan-2-C-14 was incorporated into hemoglobin of 180-day infected mice in a tenfold increase over that found in normal mice. A 20% increase in C14 activity was found in the serum. In all 180-day infected mice the serum free-amino acid carboxyl carbon levels rose above those of normal mice, indicating a decrease in utilization of serum free amino acids.

Synthesis and metabolism of tritium-labeled DL-kynurenine.

Summary 1. DL-kynurenine was labeled with tritium by the Wilzbach procedure. 2. Intraperitoneal injection of tritium-labeled DL-kynurenine into rats was followed by the excretion of labeled quinolinic acid and N1-methylnicotinamide in the urine. The evidence is definite that kynurenine can serve as a precursor of quinolinic acid and N1-methylnicotinamide. 3. During 24 hours after injection of 1 mg of labeled DL-kynurenine, 6.86% was excreted as unchanged labeled kynurenine.