Effect of an infection on vitamin A status of children as measured by the relative dose response (RDR).

The effect of an infective episode of chickenpox on the vitamin A status of preschool-aged children was evaluated by use of the relative dose response (RDR) test. Status was determined before and 30, 120, and 180 d after administration of a single oral high-dosage (200,000 IU) supplement of vitamin A. No differences in mean blood levels of retinol or percentage of children showing a positive RDR were apparent until after the infective episode that occurred approximately 90 d after dosing.

Assessment of marginal vitamin A deficiency in Brazilian children using the relative dose response procedure.

Vitamin A status was determined using fasting plasma levels and the relative dose response (RDR) procedure before and 30, 120, and 180 days after administration of an oral massive (200,000 IU) dose of vitamin A. The study was carried out in Recife, Brazil among 93 children of 7 yr or less from low income families who attended two day-care programs. The RDR procedure is conducted by obtaining a fasting blood (A0), feeding 450 retinol equivalents and obtaining a second blood specimen after 5 h (A5).

Liver levels of retinol in unselected necropsy specimens: a prevalence survey of vitamin A deficiency in Recife, Brazil.

Total retinol was analyzed in 517 necropsy specimens from children 0 to 14 yr of age, deceased of various causes in Recife, Brazil, and from eight persons, 10 to 59 yr of age, who died violently. Age and nutritional status, in that order, were found to be the major determinants of the prevalence of low reserves, children less than 1 yr of age showing the highest prevalence of deficient values. These data were extrapolated to the live population less than 5 yr of age, categorized by age and nutritional status.

Osmotic Stress-Induced Polyamine Accumulation in Cereal Leaves : II. Relation to Amino Acid Pools.

Arginine decarboxylase activity increases 2- to 3-fold in osmotically stressed oat leaves in both light and dark, but putrescine accumulation in the dark is only one-third to one-half of that in light-stressed leaves. If arginine or ornithine are supplied to dark-stressed leaves, putrescine rises to levels comparable to those obtained by incubation under light. Thus, precursor amino acid availability is limiting to the stress response.

Osmotic stress-induced polyamine accumulation in cereal leaves : I. Physiological parameters of the response.

Putrescine and spermidine accumulate in cereal cells and protoplasts exposed to various osmotica (sorbitol, mannitol, proline, betaine, or sucrose). The response is fast (1-2 hour lag), massive (50- to 60-fold increase in putrescine), and is not due to release of putrescine from a bound form or to conversion from spermidine. It rather involves the activation of the biosynthetic pathway mediated by arginine decarboxylase (ADC; EC 4.

Gradients of polyamines and their biosynthetic enzymes in coleoptiles and roots of corn.

The distribution of diamines, polyamines, and their biosynthetic enzymes arginine decarboxylase and ornithine decarboxylase in roots and coleoptiles of corn (Zea mays var Golden Cross Bantam) seedlings have been determined. Putrescine content, expressed on either a fresh weight or protein basis, increases from the tip to the base in both roots and coleoptiles. In roots, this gradient is paralleled by an activity gradient of arginine and ornithine decarboxylases.

Polyamines and plant stress: activation of putrescine biosynthesis by osmotic shock.

The putrescine content of oat leaf cells and protoplasts increases up to 60-fold within 6 hours of exposure to osmotic stress (0.4 to 0.6 molar sorbitol).

Analysis of polyamines in higher plants by high performance liquid chromatography.

A sensitive (0.01-1 nmol) method has been developed for the analysis of polyamines in higher plant extracts based on high performance liquid chromatography (HPLC) of their benzoyl derivatives (Redmond, Tseng 1979 J Chromatogr 170: 479-481). Putrescine, cadaverine, agmatine, spermidine, spermine, and the less common polyamines nor-spermidine and homospermidine can be completely resolved by reverse phase HPLC, isocratic elution with methanol:water (64%, v/v) through a 5-mum C(18) column, and detection at 254 nm.

Relation of polyamine synthesis and titer to aging and senescence in oat leaves.

Polyamine biosynthesis in senescing leaves of Avena sativa L. was measured by determining the activities of arginine decarboxylase (EC 4.1.

Polyamine oxidase in oat leaves: a cell wall-localized enzyme.

The localization and activity of polyamine oxidase (PAO; EC 1.5.3.

Polyamine-induced DNA Synthesis and Mitosis in Oat Leaf Protoplasts.

Freshly isolated protoplasts from leaves of oat seedlings (var. Victory) which do not divide when cultured on a wide range of media are capable of incorporating tritiated leucine, uridine, and thymidine into trichloroacetic acid-insoluble macromolecules. Over 70% of the leucine and uridine incorporated over an 18-hour period are found in protein and RNA, respectively, as shown by hydrolysis of the macromolecular products with a specific protease or RNase.

Dietary manipulation of serum triglycerides.

A group of children who had been treated for protein-energy malnutrition with a high-energy, high-faty diet, presented very low levels of fasting serum triglycerides (50.8 +/- 5.9 mg/dl).

The interrelationship of the concentration of hydrogen ions, bicarbonate ions, carbon dioxide and calcium ions in the regulation of renal gluconeogenesis in the rat.

1. The interrelationship of acidosis and Ca(2+) on the stimulation of gluconeogenesis by rat kidney-cortex slices was studied. 2.

Phosphoenolpyruvate carboxykinase of kidney. Subcellular distribution and response to acid-base changes.

1. A method for the assay of phosphoenolpyruvate carboxykinase is presented, based on the enzymic determination of the phosphoenolpyruvate produced by the enzyme reaction. 2.