Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D06543 (Vitamin A)
3,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vitamin A deficiency and xerophthalmia are major public health problems throughout much of the developing world. Perhaps 5 million or more children develop xerophthalmia every year of whom 1/4 million go blind. Children with mild xerophthalmia die at 4-16 times the rate of their nonxerophthalmic peers. Vitamin A supplementation of children at large may reduce mortality by at least 1/3. Given the size and significance of the problem of vitamin A deficiency and the limited resources presently available to combat it, recognition of contributory factors or conditions that identify children at increased risk would allow targeting of intervention activities for greater efficiency and effectiveness. In this study, preschool-age rural Indonesian children were reexamined every 3 months for 18 months. An average of 3228 were free of xerophthalmia at the examination initiating each of the 6, 3 month follow-up intervals. Children with respiratory disease and/or a recent history of diarrhea at the start of an interval developed xerophthalmia by the end of the interval at more than twice the rate of their healthier peers (p0.05) independent of anthropometric status. It appears that vitamin A deficiency and infections, especially diarrhea and respiratory disease, can establish a vicious cycle that induces and perpetuates ocular and systemic disease.
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PMID:Increased risk of xerophthalmia following diarrhea and respiratory disease. 357 98

In a sample of 100 pregnant and 106 lactating women, the serum levels of vitamin A, carotene, retinol-binding protein (RBP), and pre-albumin (PA) were analyzed. The study was in response to the problem of inadequate hepatic reserves and serum vitamin A levels of newborns. On the presumption that these levels are related to the Vitamin A status of mothers during pregnancy, and the Vitamin A content of breast milk during lactation, attention was given to the Vitamin A status of pregnant and lactating women in studies of maternal and child nutrition in Machakos. The women were selected at random from the total population of pregnant and lactating women with infants of 0-12 months. Blood was taken before the midday meal, centrifuged, and sera were deep frozen. Mean serum levels of the 4 biochemical parameters of vitamin A status were in the range for well-nourished population groups. Correlations of r=0.76-0.85 were found between RBP and PA, but between Vitamin A and RBP the correlation was r=0.32-0.40. Some seasonal variations reflected crop availability. A review of very little available literature shows that Vitamin A status of lactating women in Ethiopia is poorer among less privileged women. Dietary intake of retinol equivalents in West African countries being adequate, reported serum levels in these countries are also generally adequate. Xerophthalmia among young children in Machakos is rare, with the possible explanation that seasonal intake of carotene-rich foods is enough to replenish liver stores, and protein status (RBP and PA serum levels) is adequate as well.
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PMID:Vitamin A status of pregnant and lactating women as assessed by serum levels in Machakos area, Kenya. 407 26

Vitamin A is required for the normal growth maintenance and maturation of the corneal epithelium and is effective in the treatment of xerophthalmia and experimental corneal epithelial wounds when applied topically as retinoic acid. The normal route of delivery of vitamin A to the cornea has remained undefined. We collected tears from normal and vitamin A deficient rabbits and from humans and analyzed them by high pressure liquid chromatography. A peak corresponding to a retinol standard was eluted from normal rabbit and human tears but was absent from the vitamin A deficient rabbit tears. The retinol concentration in rabbit tears was 69 ng/ml (0.2 X 10(-6)M) and in human tears was 16 ng/ml (0.5 X 10(-7)M). This demonstration that vitamin A is present in the tears as retinol establishes the rationale for treatment of corneal disease with topical vitamin A.
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PMID:Vitamin A is present as retinol in the tears of humans and rabbits. 653 64

Topical retinol, tretinoin (all-trans-retinoic acid) and etretinate (a synthetic retinoid) were used in rabbits to treat experimental xerophthalmia due to vitamin A deficiency. Both 0.2% retinol and 0.1% and 0.2% tretinoin effectively reversed abnormal corneal epithelial keratinization within one to two days and restored corneal clarity within two to four days following topical application three times per day. Etretinate was ineffective in the concentration used (0.2%). In addition, application of tretinoin to one eye effectively reversed xerophthalmic changes in the other eye. Retinol did not have an effect on the other eye.
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PMID:Treatment of xerophthalmia with retinol, tretinoin, and etretinate. 673 78

Thirteen anorexia nervosa patients and 13 control subjects were examined for cataract and xerophthalmia. Although 11 patients had Vitamin A intakes below recommended daily levels for significant periods of time, there was no evidence to suggest that they had an increased incidence of pathological changes in conjunctiva or lens.
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PMID:Eye signs in patients with anorexia nervosa. 738 45

In developing countries, vitamin A deficiency (VAD) is a major contributor to child blindness and is associated with increased mortality. We assessed the vitamin A status of a Sahelien population and evaluated the correlation between the various criteria used to score xerophthalmia. The survey was carried out between June 1992 (the end of the dry season) using a representative sample of 906 children between the ages of 3 and 7 years in the district of Douentza. The population sample was selected by a two stage cluster sampling method (villages and then households). Vitamin A status was evaluated using clinical, histological and nutritional criteria. Clinical examination included testing for night blindness (XN), Bitot's spots (X1B) and corneal scars (XS). The Impression Cytology with Transfer (ICT) test described by Amedee-Manesme was used for histological analysis. Cases of follicular trachoma were recorded because of the possible influence of active trachoma on the findings of the ICT test. Nutritional status was determined by measuring the height for weight ratio according to the National Center for Health Statistics criteria. The prevalence of XN was 2.7% (1.6-3.7), significantly higher than the WHO threshold for a public health problem. The prevalence of X1B was 0.5% (0.1-1.2), and no corneal scars were detected. 31.7% of the children were suffering from malnutrition, but malnutrition did not correlate with any of the ophthalmological indicators of a public health problem. Among the 842 readable ICT tests, 265 were abnormal (31.4% of the total, 28.2-34.5). This incidence of abnormal results was unexpectedly low, in the light of the clinical results, and well below the threshold value of 50% suggested by Carlier.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Xerophthalmia. Identification of populations at intermediate risk]. 764 Aug 98

Acute infections of childhood are associated with an increased of xerophthalmia, apparently due to depletion of vitamin A stores. The mechanism responsible for this is not known. Recently, it has been reported that severe infections in adult patients (ie, sepsis and pneumonia) result in excretion of large quantities of retinol in the urine. In 44 children hospitalized for treatment of acute diarrhea we found mean urinary excretions of 1.44 mumol retinol/24 h on day 1 of hospitalization, 0.62 mumol retinol/24 h on day 2, and 0.23 mumol/24 h on day 3. Healthy control subjects matched for age did not excrete measurable amounts of retinol in the urine. Retinol excretion was associated strongly with rotavirus diarrhea and presence of fever. Furthermore, serum retinol concentration was negatively associated with duration of diarrhea before hospitalization, suggesting that urinary excretion of retinol may be an important contributor to vitamin A depletion.
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PMID:Urinary excretion of retinol in children with acute diarrhea. 776 30

Vitamin A is essential for growth, development and survival. For children in deprived settings an adequate vitamin A status may be more critical to survival protection than to growth and development. During infancy breast milk from malnourished mothers is protective against the development of xerophthalmia; it needs to be complemented after six months by other dietary sources of vitamin A to provide full health protection. Correcting the low vitamin A content of breast milk from malnourished mothers within the first four weeks of delivery by a high dose oral vitamin A supplement can be an effective short-term preventive strategy while efforts are made to improve the dietary intake for the long-term solution.
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PMID:The role of vitamin A in child growth, development and survival. 783 48

A randomized controlled clinical trial was conducted to determine the relative protection afforded by two large doses of vitamin A against subclinical vitamin A deficiency among 345 preschool children. At baseline, children either had or were at high risk of developing non-corneal xerophthalmia. Vitamin A status was assessed by the relative dose response (RDR) test, serum retinol concentration, and ocular examination before and 3 and 6 mo following one oral dose of 105 mumol or 210 mumol of vitamin A. At 3 and 6 mo, mean serum retinol concentration was significantly higher in the 210-mumol group than in the 105-mumol group. The proportion of children with a positive RDR did not differ between groups at 3 mo, but by 6 mo there were three times more children positive in the 105-mumol group. Most of the observed difference was confined to children with xerophthalmia at baseline. The relative benefit of the 210-mumol dose was related to baseline vitamin A status. The current World Health Organization recommended prophylactic dose of 210 mumol seems appropriate.
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PMID:A 210-mumol dose of vitamin A provides more prolonged impact on vitamin A status than 105 mumol among preschool children. 806 67

This article is based on a presentation given at a nutritional symposium at the Experimental Biology '93 Conference. The author describes the worldwide problem of vitamin A deficiency. Children of developing countries are particularly affected and may develop keratomalacia. Keratomalacia remains the major cause of preventable childhood blindness in developing countries. In 1987 WHO identified 37 developing countries that exhibited an increased risk for eye disease because of a deficiency of vitamin A. Vitamin A deficient populations may be identified by classic xerophthalmia (clinical symptoms) or by using 1-2 biological measurements. No single biological measurement of a subclinical deficiency was considered best. Subclinical indicators might include: plasma and/or breast milk retinol levels, dose-response testing, and functional tests measuring night blindness and eye conjunctival impression cytology. Treatment is immediate and given in 3 doses of vitamin A at concentrations related to the child's age. Children 1 year old and older are given 200,000 international units (IU), infants aged 6-12 months are given 100,000 IU, and for those aged under 6 months 50,000 IU are recommended. Intervention efforts should be customized to fit the country. WHO recommends that any strategy include the following: public awareness, infectious disease control, improved agricultural and horticultural programs, nutritional and health education programs, breast feeding promotion, vitamin A supplemental programs, and world health leaders' conferences.
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PMID:Hypovitaminosis A: international programmatic issues. 806 5


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