Yaye F. Herman

Regulation of human jejunal glycolytic enzymes by oral folic acid

The effect of oral folic acid on jejunal glycolytic enzyme activity in five fasting obese patients and in three normal male volunteers on a constant 3000 cal diet was studied. The glycolytic enzymes, fructokinase, hexokinase, glucokinase, fructose-1-phosphate aldolase, and fructose diphosphate aldolase, and the disaccharidases, sucrase, maltase, and lactase were measured. In both the fasting patients and the normal volunteers, oral folic acid significantly increased the jejunal glycolytic enzyme activities but had no effect on disaccharidase activity. When oral folic acid was discontinued in the normal volunteers, the glycolytic enzyme activities returned to control values. In the obese patients, refeeding and folic acid caused a further increase in glycolytic enzyme activities above that seen with fasting and folic acid. In contrast to oral folic acid, intramuscular folic acid, oral vitamin B(12), and oral tetracycline had no effect on glycolytic enzyme activities. These studies demonstrate that oral folic acid which is neither a substrate nor a coenzyme of these enzymes, increases human jejunal glycolytic enzyme activity in a specific fashion. This would appear to be an action of oral folic acid which has not been recognized previously.

Trace Elements and Vitamins

What might appear to be nutritionally unimportant or of only minor importance in the adult can be extremely important in the infant who may increase his body mass by 50 to 75 per cent during a few weeks of total intravenous nutrition. This dilutional factor alone might be enough to significantly deplete body stores of some micronutrients.

Effect of Germfree Status on 64Cu Excretion by the Rat

Summary The fecal excretion of radioactive copper during the first 24 hr following oral dosage was significantly lower in germfree rats than in conventional rats. Urinary excretion of 64Cu during the same period of time amounted to approximately 1% of the oral dosage and was not significantly affected by germfree conditions. Growth rates indicated that a mineral level of 120% of the recommended daily allowances for conventional rats was adequate for germfree rats despite the fact that some of the minerals may be metabolized differently by rats in the two environments.

The comparison of the 1-C14-glucose and 6-C14-glucose metabolism of reticulocyte-rich and reticulocyte-poor human red blood cells

consistent with the hypothesis that reticulocytes contain an operative pentose phosphate pathway but not a functioning Kreb’s tricarboxylic acid cycle. I T IS GENERALLY ACCEPTED that the Kreb’s tricarboxylic acid cycle (TCA cycle) is operative in immature nucleated red blood cells but not in mature non-nucleated erythrocytes .I The stage of maturation at which erythroid precursors lose the TCA cycle is not known. The demonstration in mammalian reticulocytes of mjitochondria and certain metabolic intermediates has led to the belief that the TCA cycle functions in human reticulocytes. 1,2 Rapoport and Sarkar 3,4 have shown that rabbit reticulocytes have an appreciably higher isocitric dehydrogenase activity than mature erythrocytes but that reticulocytes have only a slightly higher malic dehydrogenase. Also, Grimes5 showed that the ratio between C1402 from 1-C14-glucose and lactate produced from glucose remained constant in mature erythrocytes and in reticulocyte-rich samples obtained from patients recovering from megaloblastic anemia. This implies that a TCA cycle did not contribute significantly to the glucose metabolism in these reticulocyte-rich samples, otherwise the amount of lactate produced in the reticulocyte preparations would have been reduced proportionately and the C1402 from the 1-C14-glucose would have been raised (since 1-C14-glucose furnishes C1402 from both the pentose phosphate pathway and the TCA cycle), thus altering the ratio as compared to mature erythrocytes. We had the unusual opportunity to measure the utilization of l-C14- and 6-C14-glucose by human reticulocyte-rich preparations obtained from a patient with a mechanical hemolytic anemia with no complicating metabolic process and hence we could test whether or not human reticulocytes metabolize C14-labeled glucose consistent with the presence of a functioning TCA cycle. METHODS

Susceptibility of Primary Cultures of Feline Renal Cells to Selected Viruses

Summary The susceptibility of primary feline renal cell cultures to 24 viruses is reported. Of these, infectious bovine rhinotracheitis, vesicular stomatitis, equine abortion, vaccinia, herpes, Sendai, ECHO 10, and adenovirus 4 were shown to produce marked cytopathic effects with multiplication. Canine hepatitis virus, Coxsackie B-l through B-5, adeno 3 and 7, and parainfluenza III(SF-4) were cytopathogenic for one or more passages but did not multiply. The polio-viruses, Newcastle disease, ECHO 4, and Coxsackie A-9 had no cytopathogenic effect on the cell, and there was no evidence of viral multiplication.