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Biomedical subjects

J Bulux

Publications and source records attributed to J Bulux.

11 recordsLinked to original sources
PubMed1995

Blood retinol and beta-carotene levels in rural Guatemalan preschool children.

Plasma retinol and beta-carotene levels were measured in 502 preschool Guatemalan children from five rural hamlets. Their ages ranged from 6 to 78 months (mean: 42.9 +/- 19.2 months); 45% males and 55% females. The mean retinol value in the whole group was 0.9 +/- 0.4 mumol/l (range: 0.1 to 8.4 mumol/l). There was no significant difference between sexes in retinol mean values nor in the incidence of retinol values less than 0.7 mumol/l (22% in males, 18% in females). When grouped by age and community, significant low retinol mean values were found in two hamlets in the youngest age group (12 to 23 months) as compared to the other age-groups (p < 0.05). In the other two hamlets, there were no significant differences among retinol means by age-group. The highest prevalence of deficient retinol values by age-group was in the 12 to 23 months group (40%), and decreased as age increased. The mean value for beta-carotene in the whole group was 0.13 +/- 0.18 mumol/l (range: 0.01 to 2.23 mumol/l). There were no significant differences in beta-carotene means between sexes in the whole group. Stratifying the beta-carotene data by age-groups and community, values were significantly higher in the 48-59 months and 72-83 months groups, as compared with the other age groups in two of the communities (p < 0.05). Significant differences across communities for beta-carotene were found only in the 12 to 23 months group.

Age Factors↗
PubMed1994

Plasma response of children to short-term chronic beta-carotene supplementation.

Plasma concentrations of beta-carotene and retinol after supplementation of children with beta-carotene in supplements and in foods were compared in Guatemalan children. The children received 6 mg/d beta-carotene [1000 retinol equivalents (RE)] as purified supplements or as carrots for 20 d and the effects on plasma beta-carotene and retinol concentrations were assessed. Plasma concentrations of beta-carotene were increased by 0.59 +/- 0.65 and 0.60 +/- 0.67 mumol/L after supplementation with beta-carotene capsules for 10 and 20 d, respectively. Addition of cooked carrots to the diet resulted in no significant change in plasma beta-carotene. Fasting plasma retinol concentrations were 1.23 +/- 0.35 mumol/L and were not significantly changed in response to supplementation with either of the carotene treatments with retinyl palmitate (1000 RE/d) for 20 d. Possible explanations for the differences in effects of plasma concentrations between the two methods of supplementation are discussed.

Biological Availability↗
PubMed1992

Studies on the application of the relative-dose-response test for assessing vitamin A status in older adults.

We investigated the time course and the reproducibility of the relative-dose-response (RDR) test for assessing vitamin A status in older adults. The maximum plasma retinol response to 480 retinol equivalents (RE) of retinyl palmitate in abnormal responses was at 6 or 7 h after dosing compared with the 5-h sampling interval recommended by others for younger adults and children. With respect to reproducibility, the diagnostic concordance of two RDR tests at 7-d intervals in 14 elders was 71%. In 29% of tests, one test was abnormal and the other normal. Linear regression of the two RDR values in these 14 subjects gave a correlation coefficient of -0.08. We conclude that the procedure for the RDR should be modified when applied to persons greater than 60 y of age, and that multiple repetitions of the test are needed to provide a stable indication of vitamin A stores in an elderly individual.

Aged↗
PubMed1991

Plasma response to oral beta-carotene in Guatemalan schoolchildren.

The response to oral doses of beta-carotene (0 mg, n = 10; 15 mg, n = 20; and 30 mg, n = 21) was studied in 51 Guatemalan children aged 8-15 y, with mean fasting plasma retinol concentrations of 1.72 +/- 0.38 mumol/L. Beta-carotene was delivered with a chocolate drink containing 8.4 g fat. Serial blood sampling was performed at intervals up to 48 h. Circulating retinol concentrations remained relatively constant. The maximum increases in plasma beta-carotene after the 30- and 15-mg doses for all subjects occurred at 24 h and were 0.29 and 0.23 mumol/L, respectively. Time of maximum increase for individuals varied and average maxima over the 48-h period for individuals were 0.13 and 0.26 mumol/L for the 15- and 30-mg-treatment groups, respectively. Increased plasma beta-carotene concentrations were not predicted by recent intake of dietary vitamin A, fasting plasma concentrations, or anthropometric measurements.

Administration, Oral↗
PubMed1990

Test-retest reproducibility of the relative dose response for vitamin A status in Guatemalan adults: issues of diagnostic sensitivity.

The relative dose response (RDR) test has been used as a functional measure of whole-body stores of vitamin A in humans. We have examined the reproducibility of the RDR procedure in a population of Guatemalan adult subjects who would be expected to show a moderate prevalence of hypovitaminosis A. Fifty-one subjects were administered a standard RDR test, and the plasma samples were analyzed for retinol, tocopherol, retinol binding protein (RBP) and prealbumin (PAL). Thirty-four of the subjects underwent repeat RDR tests 7 d later. Plasma levels in fasted subjects were as follows: retinol, 1.35 +/- 0.30 mumol/L; RBP, 37.8 +/- 7.7 mg/L; PAL, 187.0 +/- 39.0 mg/L; and tocopherol, 16.6 +/- 6.2 mumol/L. RDRs ranged from -35.2% to +63.1%, with a mean of 2.6 +/- 10.4%. Overall, we observed poor within-subject reproducibility of the RDR procedure whether expressed numerically or by diagnostic classification. Moreover, in contrast to previous studies in children, we observed fewer positive RDR tests than would be expected for the population studied. Nevertheless, the mean RDR was inversely proportional to fasting retinol levels, thus confirming the validity of the biological basis of the RDR procedure in humans. Because of high intra-individual variability with this test, investigators should be cautious when using the RDR procedure in serial studies to monitor the efficacy of therapeutic interventions or subject compliance to dietary regimens.

Administration, Oral↗
PubMed1990

Weanling diarrhea: a case report.

This case report describes a 14-month-old Guatemalan boy suffering from diarrhea and malnutrition. He had been healthy and experienced normal growth until weaning, which began at six months of age. Introduction of semisolid foods at this time was accompanied by bouts of diarrhea and a reduced growth rate. After admission to hospital at 14 months of age, he was found to have protein-energy malnutrition of the edematous type (kwashiorkor) and to be infected with Giardia lamblia. Therapy with metronidazole and a high-protein diet resulted in satisfactory weight gain and cessation of the diarrhea.

Animals↗
PubMed1989

Conjunctival impression cytology: feasibility of a field trial to detect subclinical vitamin A deficiency.

Two hundred and thirty-six Guatemalan children aged 2-14 y were examined for subclinical vitamin A deficiency by use of conjunctival impression cytology (CIC). The feasibility of the technique and quality of a modified touch procedure were assessed. Neither lid speculum nor physical restraint in the form of a papoose board was used. The CIC technique was easily performed on children aged greater than 3 y but was more difficult among those less than or equal to 3 y. Laboratory processing of specimens is uncomplicated but interpretation may be problematic and requires clearly defined criteria of normal and abnormal cytology as well as careful standardization of readers.

Adolescent↗
PubMed1989

Conjunctival impression cytology (CIC) to detect subclinical vitamin A deficiency: comparison of CIC with biochemical assessments.

By use of sensitivity and specificity analysis, conjunctival impression cytology (CIC) was compared with fasting serum vitamin A levels and relative dose response (RDR) of Guatemalan children. One impression was taken from the temporal bulbar aspect of each eye, fasting serum vitamin A levels were then drawn, 480 RE of oil-based retinyl palmitate was given, and a 5-h postdosing vitamin A level was drawn (RDR procedure). For a 20% RDR cutoff, the sensitivity of CIC was 23% with a specificity of 80% and a positive predictive value of 9% (n = 213 children). Compared with fasting vitamin A levels alone (with 0.70 mumol/L as abnormal), the sensitivity of CIC was 26%, specificity was 81%, and positive predictive value was 22% (n = 221 children). There was no significant difference in the mean serum retinol level between those with abnormal and normal CIC. In this study population CIC does not identify the same group of children with marginal vitamin A as identified biochemically.

Adolescent↗