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In view of earlier results obtained with rodents, the present study was designed to investigate the effect of acute zinc deprivation in man on plasma zinc concentration and the response of platelets to aggregating agents. Three adult men consumed a formula diet based largely on soybean protein for 12 to 14 days. During the control period the diet was supplemented with 12 mg zinc per day. Without supplementation the diet supplied approximately 0.5 mg zinc per 3.0 Mcal; it contained 0.7 ppm zinc, and 0.2% phytate. After removal of the zinc supplement plasma zinc dropped rapidly and reached a minimum by the 5th day. There was a wide diurnal variation in plasma zinc concentration in one subject with the overnight fasting value being the highest and decreasing soon after the morning meal. Platelet aggregation in response to ADP and arachidonate was impaired when plasma zinc was 60 micrograms/dl or less and was restored to normal within 19 h of oral zinc supplementation. These results demonstrate that plasma zinc can be rapidly decreased by dietary zinc deprivation and that extracellular zinc plays an important role in platelet aggregation.

A total of 40% of 107 stool samples from infants 1 to 52 weeks of age were found to contain Clostridium difficile antigens, detected by counterimmunoelectrophoresis. Within the group tested, there was no detectable variation by age or sex. Infants fed formula were nearly four times more likely to carry C. difficile than were those exclusively breast fed (62 versus 16%), whereas breast-fed infants also receiving formula or solids had an intermediate rate of colonization (35%). The distributions were similar when a subgroup with the highest levels of antigen was assessed separately. These data will be useful in considering potential pathogenic activities of C. difficile colonization in infancy. Asymptomatic colonization of the intestines with Clostridium difficile occurs frequently during the first year of life. In neonatal intensive care units, carrier rates of 21 to 59% in the absence of gastrointestinal symptoms have been reported (6, 19; J.

Normative data for total body potassium on 462 children (232 boys and 230 girls) are presented. The regression of total body potassium on weight can be described as a straight line for males (grams K = 4.32 +2.12 X weight) and two significantly different lines for females (grams K = -1.50 + 2.32 X weight for weight ^ 30 kg, and grams K = 34.90 + 1.11 X weight for weight > 30 kg), with less potassium per kilogram for females weighing more than 30 kg. No sex-related difference is found between 12 and 30 kg. When the regression of total body potassium on height is examined, it is found that a logarithmic transformation of potassium values results in a similar pattern, with no sex-related differences between 100 and 135 cm and less potassium per centimeter in females over this height. For males, log K in grams = 1.761 + 0.0182 X cm of height; and for females, log Kin grams = 1.595 + 0.01942 X cm for height 1 35 cm, and log K in grams = 2.574 + 0.01215 X cm for height > 135 cm. The logarithmic transformation of K versus height is proposed as a standard because it reflects changes in slope associated with known physiologic and endocrinologic changes occurring with puberty and may be more sensitive than weight in predicting abnormal values in individual patients. SpeculationSince the regression of total body potassium on height appears to be a straight line common to both sexes 100-130 cm tall, with a diverging line indicating progressively less potassium per centimeter for females over 135 cm in height, these data were compared with available data for infants. The total body K values of infants between 50 and 80 cm in length appear to fall on a line with a steeper slope than values of children 100 to 135 cm tall. This observation suggests that, during the 1st year of life, increasing total body potassium per centimeter of length reflects maturation of body composition. Further extension of such observations to low birth weight infants might be expected to give information on their body composition. Introductiongrowth and be sensitive to pathologic changes. A semilogarithmic regression on height appears to meet these Interpretation of the clinical significance of total body criteria for total body potassium. potassium determinations depends upon normative Subjects were 232 boys and 230 girls, ages 3-18 years, data and their relations to other measures of body size.They were from a middle socioeconomic background, Presentation of normative data should be in a form in apparent good health, and were free of known acute that will reflect the physiologic changes of normal or chronic disease. They lived in or near Columbia,

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