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H Flores

Publications and source records attributed to H Flores.

At least 37 records · Page 2Linked to original sources
PubMed1988

A re-examination of the stability of retinol in blood and serum, and effects of a standardized meal.

We examined the stability of retinol in blood and serum samples, kept in the dark, under different handling procedures. Samples not protected from contact with air oxygen were highly unstable, even when kept at ice temperature. Samples collected under anaerobic conditions, with Vacutainer Tubes, or treated with nitrogen after collection to displace the air from the tubes were stable during the usual interval between collection and freezing or analysis in biochemical surveys. Ingestion of a moderate amount of vitamin. A significantly increased serum retinol concentrations in normal volunteers, showing the importance that survey samples be preprandial.

Adult↗
PubMed1988

Intrahepatic distribution of vitamin A in humans and rats.

Liver vitamin A was determined in 10 different regions of the liver from 13 rats and 17 human individuals deceased of various causes. Linear regression analysis and comparison of the values obtained from the different anatomical regions showed that, despite a high degree of heterogeneity in distribution and lack of a consistent pattern, samples from any of the sites analyzed ensure representativeness of the whole liver concentration, taken as the average of the values from the 10 samples of each liver. This means that properly trained personnel, but not necessarily specialized, could draw the liver samples, thus significantly reducing the cost of surveys of vitamin A status based on liver reserves of the vitamin determined at autopsy.

Animals↗
PubMed1987

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. At 180 d postsupplementation, 74% of children who had been infected tested positive by the RDR, indicative of an inadequate liver reserve of vitamin A, in contrast to only 10% who had not been infected. Paired RDR observations at 0 and 180 d postsupplementation confirmed that the infective episode caused an accelerated depletion of liver reserves of vitamin A.

Chickenpox↗
PubMed1984

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. By using the criteria that liver reserves of vitamin A less than 5 and 20 micrograms/g denote states of high risk and inadequacy, respectively, approximately 3 and 17% of children 0 to 4 yr of age in the live population of Recife were estimated to fall in the high risk and inadequate status group, respectively. None of the persons who died violently was at high risk and only one had inadequate reserves. These estimates agree with previous prevalence figures from clinical and biochemical surveys. Thus, the direct assessment of concentrations of vitamin A in the liver at necropsy is a simple, inexpensive, and noninvasive procedure for estimating the vitamin A status of children.

Adolescent↗
PubMed1984

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). The RDR-(A5-A0)/A5 X 100. A single massive oral dose of vitamin A was given after conducting the base-line RDR test. The RDR procedure was repeated at 30, 120, and 180 days. Weight and height measurements were obtained at each observation and the bloods were analyzed for Hb, total protein, and serum iron, as well as vitamin A. Serum albumin was determined in 120- and 180-day bloods. Serum iron levels were improved 30 days after supplementation with the massive dose of vitamin A. The RDR procedure was found practical to apply in mildly undernourished children under nonclinical condition. In this group of low income children presumed to be habitually ingesting minimally adequate diets, a serum vitamin A level of 20 micrograms/dl or less invariably was associated with an elevated RDR test. Blood levels between 20 to 40 micrograms/dl were not consistently predictive of the RDR response. All elevated RDR tests reverted to normal after supplementation with vitamin A, presumably indirectly indicating a presupplementation inadequate vitamin A status. Hence, the RDR was a more sensitive indicator of inadequate vitamin A status than was only a serum level of vitamin A when blood levels were above 20 micrograms/dl.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1979

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). When the diet was changed to a high-energy, low-fat formula, these levels increased rapidly to normal values (104.9 +/- 19.2 mg/dl). Reversing the dietary change produced the opposite effect within 2 days. This effect was also studied in 14 normal adults, who received a high-fat diet ad libitum during 5 days. Meals were prepared from common foodstuffs with a high fat content. The hypotriglyceridemic effect occurred in all volunteers. A close relationship was observed between the initial triglyceride concentration and the decrement produced by the high-fat diet (r = 0.97), which did not affect serum cholesterol levels. No consistent response of serum free-fatty acids was detected, while serum proteins remained within normal values. Despite the rather high energy intake, most subjects lost weight during the experimental period. The level of fasting serum triglycerides of the adult volunteers was negatively correlated to the fat content of their self-selected diets. These results are discussed in relation to current ideas about fat requirements.

Adult↗
PubMed1973

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. Ca(2+) stimulated gluconeogenesis from glutamine, glutamate, 2-oxoglutarate, succinate, malate, pyruvate, lactate and fructose, but not from galactose. 3. The [Ca(2+)] needed for optimum gluconeogenesis was about 2mm, but at this concentration, acidosis, produced in vitro by a decrease of [HCO(3) (-)] in the medium at constant pCO(2) or by an increase in pCO(2) at constant [HCO(3) (-)], did not stimulate gluconeogenesis. 4. In the absence of Ca(2+), acidosis (low [HCO(3) (-)]) stimulated gluconeogenesis from glutamine, glutamate, 2-oxoglutarate, succinate, malate, pyruvate and lactate but not from fructose or galactose. With succinate as substrate, the stimulatory effect of acidosis (low [HCO(3) (-)]) disappeared at Ca(2+) concentrations above 1.0mm. 5. The [HCO(3) (-)] was the most important determinant of the acidosis effect since a decrease of pH caused by an increase in pCO(2) did not uniformly stimulate gluconeogenesis, whereas a decrease in [HCO(3) (-)] without a change in pH consistently stimulated glucose formation in a way similar to the stimulation produced by acidosis (low [HCO(3) (-)]) in the absence of Ca(2+). 6. Acidosis in vitro inhibited the rate of decrease of activity of phosphoenolpyruvate carboxylase in slices, and Ca(2+) caused an increase in the activity of fructose 1-phosphate aldolase. 7. Respiratory acidosis in vitro caused an increase in the activity of phosphoenolpyruvate carboxylase in kidney cortex and an increase in gluconeogenesis from glutamine. 8. Possible points of interaction between Ca(2+), H(+) and HCO(3) (-) with the gluconeogenic sequence are discussed.

Acidosis↗
PubMed1971

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. The subcellular distribution of phosphoenolpyruvate carboxykinase in the kidney of several animal species resembled the distribution in the liver. 3. The rise in enzyme activity in the kidney cortex of rats made acidotic by feeding with ammonium chloride was not prevented by administration of ethionine or actinomycin. 4. The possibility is suggested that in the kidney acidosis causes activation of an inactive form of the enzyme already present.

Acidosis↗