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In prior work, a 50 kDa protein was purified to homogeneity from rat urine. This protein reduces food intake when injected into rats and is the only natural substance other than satietin known to be effective for long (24 hour) time periods and which does not make animals ill. However, when attempts were made to repeat the purification, contamination appeared in the 50 kDa fraction. The present contribution documents successful reisolation of the 50 kDa anorexigen by an improved method. Reisolation involved Cibacron blue-Sepharose, DEAE-Sephacel and Sephacryl S-200 chromatography, and SDS disc preparatory electrophoresis. The reisolated 50 kDa anorexigen contains no detectable carbohydrate. Partially purified preparations of the 50 kDa anorexigen were fragmented with trypsin and proteinase K without loss of anorexigenic activity. It is concluded that the 50 kDa anorexigen may be reproducibly purified to homogeneity and may contain within its amino acid sequence a peptide which is the basis of its anorexigenic activity.

There is positive correlation between high dietary intake of sodium and prevalence of hypertensive disease. Dietary potassium shows a negative correlation with this prevalence. Racial background of subjects may affect such relationships. This is a study of the relationships between ethnicity and blood pressure in young adults of six ethnic groups in Hawaii. Body weight, electrolyte excretion, which may reflect intake, and blood pressure of the subjects are reported here. Caucasians and Hawaiians and part-Hawaiian young adults tended to be taller and heavier than the Chinese, Filipinos, Japanese, and Koreans. Both systolic and diastolic pressures were significantly higher in males than in females (all races combined). No significant differences between sexes or races were found in urinary excretion of sodium and potassium or in urinary sodium:potassium ratios. Body weight and Quetelet's Index but not sodium:potassium ratio correlated significantly with diastolic pressure.

A potent, homogeneous, 50 kDa protein which transiently depresses food intake of rats up to 24 h after injection was isolated from rat urine. It was prepared from an ethanolic benzoic acid precipitate of urine. The material was subjected to DEAE-Sephacel chromatography, whereupon four fractions (DEAE pools a, b, c, and d) were obtained. The latter three contained anorexigenic activity. DEAE pools b and c were subjected to further purification on columns of Sephacryl S-300 eluted with buffer containing 8 M urea. One of the subfractions of DEAE pool b contained only one protein as judged by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. This protein had a molecular weight of 50,000 and was active in reducing 24 h food intake at a dose of 130 micrograms/100 g bodyweight.

Thirty men were studied during a 34-day intensive training exercise conducted by the U.S. Army. All soldiers were followed to determine the effect of such training, designed to simulate wartime operations, on selected zinc parameters. The soldiers consumed a nutritionally adequate diet made from fresh foods (A rations) prepared at the training site. Dietary intake, weight change, serum zinc, alkaline phosphatase activity, and urinary zinc excretion were measured. The 34-day intensive training exercise was associated with weight loss, depressed serum zinc levels, and elevated urinary zinc excretion. Alkaline phosphatase activity was not altered by the training exercise. The depressed serum zinc concentration could not be explained by the parameters measured. Weight loss was positively correlated with urinary zinc excretion. The functional significance of a depressed serum zinc concentration on performance deserves further study.

Human dietary requirements for essential mineral nutrients are not precisely known. Estimates differ according to the method used. For magnesium, balance studies yield values from 300 to 354 mg/day for American women and from 420 to 483 mg/day for men. Lower figures are obtained from measurements of urinary and sweat losses. Little is known about requirements for children. Actual intakes in the United States are about 202 mg/day for children from 1 to 5 years old, 228 mg/day for women, and 331 mg/day for men (19-50 years old). Intakes are lower in blacks. Calcium requirements for adults have been estimated as the amount of dietary calcium required to ensure absorption of 150 mg/day. This amount is about 540 mg/day. A similar figure is assumed for children. Intakes are 870 mg/day for children, 683 mg/day for women, and 948 mg/day for men. Again, intakes are lower in blacks. Dietary requirements are used as the basis for recommended dietary intakes, but the latter are generally set higher to ensure adequate intakes. Selected 1980 Recommended Dietary Allowances (RDAs) set by the Food and Nutrition Board of the National Research Council are for magnesium (mg/day): children 1-3 years 150; 4-6 years 200; 7-10 years 350; men 19-50 years 350; women of any age 300. Selected RDAs for calcium (mg/day) are: children 1-10 years 800; men and women 15-18 years 1,200; 19-50 years 800. An extra 150 mg of magnesium and 400 mg of calcium are recommended daily in the diets of pregnant or lactating women.