Mild vitamin A deficiency and risk of respiratory tract diseases and diarrhea in preschool and school children in northeastern Thailand.

A cross-sectional study, a follow-up study, and an intervention trial were carried out to investigate the association between mild vitamin A deficiency and the occurrence of diarrhea and respiratory diseases. Cross-sectional analysis was performed among 1,772 children, aged 1-8 years, in the Sakon Nakhon province of northeastern Thailand. Children with a history of diarrhea or respiratory disease had lower levels of serum retinol and retinol-binding protein. Adjusted for age, sex, nutritional status, and level of urbanization, logistic regression using data for 877 children showed a negative association between serum retinol and both diarrhea and respiratory diseases. A follow-up three months later (n = 146 children) showed that children with deficient serum retinol (less than 0.35 mumol/liter) had a fourfold greater risk of respiratory disease (p less than 0.01). No relation was found for diarrhea. An intervention trial (n = 166 children aged 1-5 years) showed that, during 2 months of follow-up after administration of oral vitamin A (200,000 IU), the control group (aged 3-5 years) had a higher incidence of respiratory disease (2.9 times) as well as diarrhea (3.1 times). Between 2 and 4 months, a significantly (p less than 0.025) higher incidence of respiratory diseases (2.5 times) could be observed in children aged 1-2 years. This study supports earlier reports on a greater risk of respiratory diseases and of diarrhea in mild vitamin A deficiency. Supplementation reduced the incidence of both diarrhea and respiratory disease for a period of at least 2 months.

Vitamin A intervention: short-term effects of a single, oral, massive dose on iron metabolism.

A group of 134 school children aged 3-9 y, with signs of conjunctival xerosis, from the rural area of the Sakorn Nakhon province in Northeast Thailand were selected for a controlled study on the short-term effect (2 wk) of a single, oral high dose of vitamin A on iron metabolism. After collection of the baseline data, children within villages were randomly assigned to receive the capsules (n = 65) or serve as control subjects (n = 69). Two weeks after supplementation significant increases of retinol, retinol-binding protein, hemoglobin, hematocrit, serum iron, and saturation of transferrin were found in the supplemented group. Ferritin concentrations did not change significantly. These short-term changes completely exclude seasonal effects and change in morbidity. This study provides further evidence of a causal association between vitamin A and iron metabolism. In areas where vitamin A deficiency is endemic, periodic massive vitamin A dose programs can also improve iron status of the population.

Iron metabolism and vitamin A deficiency in children in northeast Thailand.

To investigate the association between vitamin A and iron metabolism, two studies were carried out: a cross-sectional study and an intervention trial. The cross-sectional analysis was carried out in 1060 children aged 1-8 y. Multiple-regression analysis was used to adjust for effects of age, gender, indices of the protein nutritional status, and infections. Retinol was significantly associated with hematocrit, serum Fe, transferrin, ferritin, and saturation of transferrin (%ST). To obtain further evidence as to whether this observed association is a causal one, an intervention trial was carried out. After collection of the baseline data of 300 children, 166 children with a hemoglobin concentration less than 7.5 mmol/L were selected. A random sub-sample of 78 children received vitamin A capsules; the other children served as control subjects. Two months after supplementation significant differences, adjusted for age, were found for retinol, retinol-binding protein, serum Fe, and %ST between the supplemented and the control group. After 4 mo none of the indices were found to be significantly different between the supplemented and the control group. Periodic massive doses of vitamin A may play a role in improving the Fe status as well.

The total free radical trapping ability of cord blood plasma in preterm and term babies.

The interaction between various antioxidants may be important in protecting the newborn baby against oxygen toxicity. We studied the total radical trapping capacity of the antioxidants in plasma (TRAP) and compared the TRAP level in the preterm and term baby (cord blood) with that in adults. In addition, the concentrations of various known antioxidants were measured and the theoretical contribution of these antioxidants to the TRAP calculated. The measured and calculated TRAP were higher in the newborn babies than the adults. The uric acid concentration was similar in the three groups but the vitamin C concentration was higher and the vitamin E and sulfhydryl concentrations were lower in the newborn babies. In contrast to the adult group, the measured TRAP in the newborn babies did not correlate with the calculated TRAP. This may be due to differences in inhibition or recycling of antioxidants in the newborn and adult groups. Theoretical considerations showed that there may be a large unidentified group of antioxidants that contribute to measured TRAP in plasma. Bilirubin and beta-carotene were measured (higher and lower concentrations, respectively, in the newborn) in an attempt to identify these antioxidants. The efficient plasma radical trapping capacity in the cord blood may partly compensate for deficiencies in other components of the antioxidant defenses, e.g. cellular enzymes, at the time of birth.

A prevalence study of vitamin A deficiency and xerophthalmia in northeastern Thailand.

An epidemiologic survey of the prevalence of xerophthalmia and vitamin A deficiency was conducted in May and June 1985 in a multistage random sample of 1,772 children 1-8 years of age from 16 rural villages and the capital city of the Sakon Nakhon province in northeastern Thailand. Data of clinical eye examinations were available for 92% (n = 903) of the eligible children aged 1-5 years (n = 982); history of night blindness was obtained from a reliable source from 93% (n = 1,644) of the whole sample; and biochemical data were available for 60% (1,060) of the children examined. The distribution of clinical signs of xerophthalmia and serum retinol levels differed between the rural and urban areas. In the urban area, no signs of xerophthalmia or deficient serum retinol levels were found in the preschool children examined. The prevalence of night blindness in the rural area was 1.3% in children aged 1-5 years (95% confidence interval (Cl) 0.7-1.9); Bitot's spots were seen in 0.4% (95% Cl 0.1-1.0); 12.7% (95% Cl 9.9-15.5) showed deficient serum retinol levels (less than 0.35 mumol/liter). Of the children aged 1-8 years, 9.6% (95% Cl 7.8-11.4) showed deficient serum retinol levels. In the rural area, the prevalence of night blindness, Bitot's spots, and deficient serum retinol levels indicates a problem of public health importance according to World Health Organization criteria.

The effect of vitamin A supplementation on tear fluid retinol levels of marginally nourished preschool children.

Vitamin A has been determined in tear fluid and blood plasma of marginally nourished Thai children before and after supplementation with a single, oral dose of 110 mg retinyl palmitate. After two months a significant rise of tear fluid retinol levels of the supplemented group was observed as compared to the non-supplemented group, while after four months no difference could be found. Determination of vitamin A levels in tear fluid may be useful in clinical eye research, with special regard to xerophthalmia.

Fluorometric determination of retinol in human tear fluid using high-performance liquid chromatography.

A fast and sensitive high-performance liquid chromatographic (HPLC) method for the determination of vitamin A (all-trans retinol) in 50 microliter human tear fluid is described. After deproteinization with ethanol and extraction with n-hexane, retinol is separated from the extract on a straight-phase HPLC column and detected fluorometrically. Vitamin A can be determined in concentrations as low as 0.4 ng/ml. A single analysis can be completed in 12 min while the analysis of a series of 60 samples takes about 8 h. The within-assay and between-assay coefficients of variation were 3.1 and 4.2% resp. The between-assay analytical recovery of retinol added to tear fluid was 97.4 +/- 6.0% (mean +/- SD). Retinol was determined in tear fluid of nine adult volunteers. The amounts observed ranged from less than 0.4 - 10.6 ng/ml.

Persistent low plasma vitamin E levels in premature infants surviving respiratory distress syndrome.

Plasma vitamin E levels were determined serially in preterm infants surviving respiratory distress syndrome (RDS) and in premature infants without RDS (control). Vitamin E intakes of the RDS and control infant group were not significantly different. The results of the study show that preterm infants surviving RDS have a persistent low plasma vitamin E level throughout the first 8 weeks of life. In contrast, in premature infants without RDS the plasma vitamin E level gradually increases to the adult level throughout the first 8 weeks of life. It is concluded that data on plasma vitamin E levels in premature infants with and without RDS should not be pooled together to obtain reference values. It is further suggested that premature infants with RDS might need more supplemental vitamin E than premature infants without RDS.

Urinary excretion of 3-methylhistidine and creatinine by healthy Dutch children during day and night. The influence of age and sex.

The urinary excretion of 3-methylhistidine and creatinine and the urinary 3-methylhistidine to creatinine excretion ratio during day and night were investigated in a group of 103 healthy, normally fed Dutch children (52 boys and 51 girls) aged 2-17 years. The 3-methylhistidine to creatinine ratio of the night urine appeared to be significantly higher than that of the urine produced during the day, irrespective of sex and age. This difference was about 30%. For both sexes it was found that the 3-methylhistidine and creatinine excretion increased and that the 3-methylhistidine to creatinine ratio decreased with age. Although the creatinine excretion by boys was significantly higher than that by girls of the same age, no differences were seen between the sexes with respect to the 3-methylhistidine excretion or the 3-methylhistidine to creatinine ratio. A clear linear relation was found between the day or night urine and the 24 h urine with respect to the 3-methylhistidine to creatinine ratio. However, no such relation was observed between the day and the night urine. These results are discussed in relation to the use of smaller urine samples instead of 24 hour urine in the study of 3-methylhistidine excretion.

Fluorimetric determination of menadione sodium bisulphite (vitamin K3) in animal feed and premixes by high-performance liquid chromatography with post-column derivatization.

A high-performance liquid chromatographic (HPLC) method for the determination of menadione sodium bisulphite (vitamin K3) in animal feed and premixes is described. After aqueous extraction, the vitamin is converted into menadione, which is extracted and separated on a reversed-phase HPLC column. After menadione has been reduced in a post-column reaction coil, fluorimetric measurement of the reduced vitamin permits the determination of menadione sodium bisulphite in animal feed and premixes at concentrations as low as 0.02 microgram/g. Several types of animal feed have been analysed according to the method described and also with the European Community colorimetric method. From high concentration levels down to ca. 15 micrograms/g the results obtained with the two methods are in good agreement. For concentrations in the range 1-3 micrograms/g (complete diets) a tendency to lower results by the HPLC method is observed. The detection limit of the HPLC method is considerably lower than that of the European Community colorimetric method. The within-assay coefficient of variation of the method applied to feeds is 6.0%. The within-assay analytical recovery of menadione sodium bisulphite added to feeds is 94.4 +/- 6.8% (mean +/- S.D.).

Fluorometric determination of total vitamin C in whole blood by high-performance liquid chromatography with pre-column derivatization.

A reliable and semi-automated high-performance liquid chromatographic (HPLC) method is described for the determination of total vitamin C in whole blood. After deproteinization of whole blood and enzymatic oxidation of l-ascorbic acid to dehydro-l-ascorbic acid, the latter is condensed with o-phenylenediamine to its quinoxaline derivative. This derivative is separated on a reversed-phase HPLC column and detected fluorometrically. Total vitamin C in whole blood can be determined in concentrations as low as 0.2 mumol/l. Special attention was paid to the stability of vitamin C in whole blood and of its quinoxaline derivative in the extract. Results of our investigations showed that total vitamin C in whole blood is stable for eight days at -20 degrees C, provided ethyleneglycol-bis-(beta-amino-ethyl ether)-N,N,N',N'-tetraacetic acid and glutathione are immediately added to the blood sample. The quinoxaline derivative of vitamin C in the blood extract is stable for at least 24 h if stored in the dark at 4 degrees C. Routine vitamin C determinations can be carried out in a series of 100 samples within 48 h. The within-assay and between-assay coefficients of variation were 3.7% and 4.6%, respectively. The between-assay analytical recovery of l-ascorbic acid added to whole blood samples was 97.0 +/- 7.0% (mean +/- S.D.). Reference values of vitamin C in whole blood of normal healthy Dutch adults were found in the range 20-80 mumol/l.

High-performance liquid chromatographic determination of urinary free catecholamines with electrochemical detection after prepurification on immobilized boric acid.

A reliable high-performance liquid chromatographic method is presented for the determination of the urinary free catecholamines noradrenaline, adrenaline and dopamine. Urine is purified on a column of immobilized boric acid. Catecholamines are separated by ion-pair reversed phase high-performance liquid chromatography and detected electrochemically. The method is suited for routine analysis. It allows the determination of urinary free catecholamines in concentrations as low as 1 microgram/1 for noradrenaline and adrenaline and 5 micrograms/1 for dopamine. A single analysis can be completed within 1 h. Routine analyses can be carried out in a series of 40 samples within 2 days. The within-assay and between-assay coefficients of variation of the analyses in urine were both 2.9% for noradrenaline, both 5.0% for adrenaline, and 1.9 and 2.1% for dopamine. The chromatographic properties of the immobilized boric acid were investigated. In particular, the elution pattern of a series of catecholamine metabolites and analogues was determined. Under the conditions used, only basic compounds containing both a vicinal hydroxyl configuration and a primary or secondary amino group adsorb and elute together with the free catecholamines.

A reliable semiautomated method for the determination of total thiamine in whole blood by the thiochrome method with high-performance liquid chromatography.

A sensitive and reliable method for the determination of total thiamine (vitamin B1) in whole blood has been developed which is suited for routine analysis. After extraction, and enzymatic hydrolysis of thiamine phosphate esters, thiamine is separated from interfering compounds by a fully automated high-performance liquid chromatographic (HPLC) system. Thiamine is detected fluorometrically as thiochrome. By calculating the concentration of thiamine on-line with the aid of a computer, it is possible to complete one analysis within four hours. Routine thiamine determinations can be carried out in a series of 120 samples within 48 hours. The within-assay and between-assay coefficients of variation of the analysis of total thiamine in whole blood were 4.2 and 4.4%, respectively. The between-assay analytical recovery of thiamine diphosphate added to blood samples was 99.9 +/- 11.7% (mean +/- SD). The HPLC method described has been applied also to the analysis of thiamine in plasma and erythrocytes. In agreement with other reports, it was found that about 80% of total thiamine of whole blood is present in the erythrocytes. Reference values of thiamine in whole blood of the human were found in the range 95-155 nmol/l.

Semi-automated fluorometric determination of pyridoxal-5'-phosphate (vitamin B6) in whole blood by high-performance liquid chromatography (HPLC).

A sensitive and reliable method for the determination of vitamin B6 as pyridoxal-5'-phosphate (PLP) in whole blood is described. After acid extraction of PLP, a fully automated high-performance liquid chromatographic (HPLC) system is used to separate PLP from interfering compounds. PLP is detected fluorometrically as its semicarbazone. By calculating the concentration of PLP on-line with the aid of a computer, it is possible to run one hundred and twenty-five samples within forty-eight hours in routine analysis. The within-assay and the between-assay coefficients of variation of the analysis of PLP in whole blood were 3.3 and 4.7% respectively. The between-assay analytical recovery of PLP added to whole blood was 100.0 +/- 7.1% (mean +/- SD). Reference values of PLP in human blood were found in the range 55-110 nmol/l.