Xerophthalmia and protein malnutrition in Bantu children

Toxocara canis: Impact of preweaning nutritional deprivation on the pathogenesis of pneumonia in the mouse

The present study was conducted to better understand the immure response to Toxocara canis pneumonia in mice with preweaning nutritional deprivation. Breast-fed Swiss mice, undernourished due to large litter size (up to 15 pups) and paired controls with only 5-8 pups were used. At 21 days old, both groups were infected with T. canis larvae. Liver retinol, retinyl palmitate, and inflammatory infiltrate in lungs were compared in both groups. Significantly lower levels of retinol and retinyl palmitate in liver tissue confirmed the hypovitaminosis A (P < 0.0001 for both comparisons) in the nutritionally deprived animals. Histological analysis showed similar eosinophilic infiltration in both groups at day 3 but was significantly more severe in undernourished mice at day 20 post-infection (P = 0.01). The present findings indicate that preweaning undernourishment is associated with a more severe inflammation in response to T. canis pneumonia. It suggests that vitamin A deficiency that persists after nutritional rehabilitation, may contribute to the severity of T. canis infection. The authors suggest that nutritional status should be carefully investigated in patients with more severe clinical findings.

Vitamin A and infancy. Biochemical, functional, and clinical aspects

Vitamin A is a very intriguing natural compound. The molecule not only has a complex array of physiological functions, but also represents the precursor of promising and powerful new pharmacological agents. Although several aspects of human retinol metabolism, including absorption and tissue delivery, have been clarified, the type and amounts of vitamin A derivatives that are intracellularly produced remain quite elusive. In addition, their precise function and targets still need to be identified. Retinoic acids, undoubtedly, play a major role in explaining activities of retinol, but, recently, a large number of physiological functions have been attributed to different retinoids and to vitamin A itself. One of the primary roles this vitamin plays is in embryogenesis. Almost all steps in organogenesis are controlled by retinoic acids, thus suggesting that retinol is necessary for proper development of embryonic tissues. These considerations point to the dramatic importance of a sufficient intake of vitamin A and explain the consequences if intake of retinol is deficient. However, hypervitaminosis A also has a number of remarkable negative consequences, which, in same cases, could be fatal. Thus, the use of large doses of retinol in the treatment of some human diseases and the use of megavitamin therapy for certain chronic disorders as well as the growing tendency toward vitamin faddism should alert physicians to the possibility of vitamin overdose.

Vitamin A supplementation: implications for morbidity and mortality in children

Vitamin A deficiency impairs epithelial integrity and systemic immunity and increases the incidence and severity of infections during childhood. However, findings from vitamin A supplementation trials are not consistent. Supplementation has resulted in significant reductions in mortality in several (but not all) large community-based trials among apparently healthy children. In hospital-based studies, vitamin A supplements have been consistently found to reduce the severity of measles infection, but no effect on nonmeasles respiratory infections has been observed. In some cases, the supplements were associated with an apparently increased risk of lower respiratory infection. Vitamin A supplements also reduced the severity of diarrhea in most (but not all) trials. Potential explanations for the differences in efficacy across trials are reviewed. While vitamin A supplementation is effective in reducing total mortality and complications from measles infections, it is likely to be more effective in populations suffering from nutritional deficiencies.

Corneal ulceration in Tanzanian children: relationship between malaria and herpes simplex keratitis

Two 3-year prospective studies from 1982-1984 and 1986-1988 in Tanzania identified 189 children with corneal ulceration, of whom 92 (48.7%) were due to herpes simplex keratitis. In 1982-1984 herpes simplex keratitis was responsible for 35.5% of corneal ulcers (38 of 107), compared with 65.8% (54 of 82) in 1986-1988 (P = 0.00006). It is postulated that the increase in corneal ulceration due to herpes simplex keratitis can be attributed to an increase in the incidence and severity of malaria infection.

Corneal ulceration, measles, and childhood blindness in Tanzania

One hundred and thirty Tanzanian children with corneal ulceration were clinically examined to determine the cause of the ulceration. 37% of the ulcers were associated with recent measles infection and 38% of the children had bilateral ulceration. Herpes simplex virus infection was the commonest cause of ulceration in the series, but vitamin A deficiency was the major cause of bilateral ulceration, subsequent blindness, and mortality in this series. Other significant causes of childhood corneal ulceration were the use of traditional eye medicines, confluent measles keratitis, and ophthalmia neonatorum. We discuss the various mechanisms by which measles causes corneal ulceration, and the priorities in prevention and management of corneal ulceration in African children.

Decreased hepatic retinyl palmitate hydrolase activity in protein-deficient rats

28-day-old weanling rats were fed a diet containing 3% casein as the only source of protein for eight weeks to induce protein deficiency. When compared to control animals (fed a diet containing 25% casein), these rats had significantly lowered body (5.2-fold reduction) and liver (2.5-fold reduction) weights. The circulatory level of retinol (nmol per ml plasma) as well as retinol (nmol per g tissue) in the liver of these protein-deficient animals were also reduced significantly, although their liver concentration of retinyl palmitate (nmol per g tissue) was comparable to that of the control group. Assay of liver tissue for retinyl palmitate hydrolase activity revealed a 4-fold reduction (compared to that of control animals) of specific enzyme activity (nmol retinol formed per g protein per h). These findings suggest that severe protein deficiency results in a decreased hydrolysis of retinyl esters in the liver, which may be in part responsible for the reduced level of metabolically 'active' retinoids available for normal physiological functions.

Increased mortality in children with mild vitamin A deficiency

An average of 3481 preschool-age rural Indonesian children were re-examined every 3 months for 18 months. The mortality rate among children with mild xerophthalmia (night blindness and/or Bitot's spots) was on average 4 times the rate, and in some age groups 8 to 12 times the rate, among children without xerophthalmia. Mortality increased, almost linearly, with the severity of mild xerophthalmia (night blindness, Bitot's spots, and the two combined). These relations persisted after stratification for respiratory disease, wasting, gastroenteritis, pedal oedema, and childhood exanthems. Mild vitamin A deficiency was directly associated with at least 16% of all deaths in children aged from 1 to 6 years. These results suggest that mild xerophthalmia justifies vigorous community-wide intervention, as much to reduce childhood mortality as to prevent blindness, and that night blindness and Bitot's spots are as important as anthropometric indices in screening children to determine which of them need medical and nutritional attention.

Effects of vitamin A deficiency on the ocular surface

Vitamin A deficiency remains an important cause of ocular morbidity among patients with chronic liver disease and lipid malabsorption, and is a major cause of blindness in developing countries. Early ocular surface changes include keratinization of the conjunctiva and development of superficial punctate keratopathy. More severe deficiency results in corneal keratinization, ulceration, and necrosis. Vitamin A is necessary for normal differentiation of nonsquamous epithelium; keratinization is a direct consequence of its deficiency. Exposure exacerbates the process and surface phenomena, especially localized drying from loss of mucus-secreting goblet cells, reduced aqueous tear production, and irregularities of the keratinized surface may all contribute to stromal melting, which can occur in the absence of inflammatory infiltration or bacterial invasion. Surface abnormalities respond rapidly to systemic vitamin A. Significantly, corneal changes disappear long before the reappearance of goblet cells. Inflammation sometimes masks or reverses the xerotic process.

Nutritional blindness in Africa

Nutritional blindness is loss of useful vision resulting from vitamin deficiency. A malnutrition Xerophthalmia means all the ocular manifestations of inadequate metabolism of vitamin A, nutritional blindness being the end result of the most severe cases. The estimated overall prevalence of nutritional blindness in Africa is very low, below the WHO levels of significance, although isolated clusters of locally high prevalence exist, usually in arid, sparsely-populated regions. The peak age group affected is 2-year olds, with most nutritional blindness having its effect before age 6 years. Xerophthalmia may be considered as a serious side effect of protein-energy malnutrition (PEM). When associated with corneal sequelae of xerophthalmia, PEM has an estimated overall mortality of 50%. Intervention programs, therefore, are more appropriately aimed at the broader condition of life-threatening PEM than at the specifically vision-threatening problem of xerophthalmia. Parameters of significant prevalence detection are discussed, and the relative merits of different forms of vitamin A-specific intervention programs are weighed.

Mortality associated with mild, untreated xerophthalmia

The high mortality rate among children with severe corneal xerophthalmia is well recognized. The present study investigates, for the first time, mortality among the very much larger number of otherwise healthy free-living children with mild xerophthalmia (night blindness and Bitot's spots). An average of 3481 children (under 6 years of age) living in six Indonesian villages were reexamined by an ophthalmologist, pediatrician, and nutritionist every 3 months for 18 months. The overall prevalence of mild xerophthalmia was 4.9%. During the 18 months of observation, 132 children died. Of these, 24 had mild xerophthalmia and 108 had normal eyes at the 3-monthly examination preceding their death. Mortality rates were calculated for each 3-month interval by classifying all children by their ocular status at the start of the interval, and then dividing the number of deaths within the interval by the number of children of the same ocular status followed up for that interval. Mortality rates for the six 3-month intervals were then added together, and the results expressed as deaths per 1000 "child-intervals" of follow-up. Overall mortality rates for children with mild xerophthalmia and for children with normal eyes were 23.3 and 5.3, respectively, a ratio of 4 to 1. Excess mortality among the mildly xerophthalmic children increased with the severity of their xerophthalmia. Mortality rates for children with night blindness, with Bitot's spots, and with the two conditions concurrently were 2.7, 6.6, and 8.6 times the mortality rate of non-xerophthalmic children. This direct, almost linear relation between mortality and the severity of mild xerophthalmia was still present after standardizing for age and for the presence or absence of respiratory infection and protein-energy malnutrition. In the population studied, 16% of all deaths in children 1 to 6 years of age were directly related to vitamin A deficiency identified by the presence of mild xerophthalmia. These results suggest: that the existence of mild vitamin A deficiency in a community justifies initiation of vigorous intervention measures to reduce mortality, as much as to prevent the rarer cases of blindness; that night blindness and Bitot's spots should be accorded the same respect as is low "weight for height" in identifying those children in urgent need of medical attention; that ocular criteria used for determining the existence and severity of a vitamin A problem be reevaluated; and that the ophthalmic community, which has long been responsible for managing xerophthalmia, must now re-alert nutritionists, pediatricians, and public health workers to the serious systemic consequences accompanying even mild

Bilateral corneal leukomas

We present this case to suggest that xerophthalmia should be considered in the differential diagnosis of children from less developed countries with corneal leukomas, particularly when it is not clear if the opacities are congenital. With more children from less developed countries being referred for adoption in America, and with continuing refugee groups coming to America, other unsuspected cases of xerophthalmia may be seen.

Keratomalacia in the cachectic hospitalized patient

Keratomalacia occurred in two cachectic hospitalized patients, each with severe vitamin A-protein deficiency secondary to a lethal disease. Prompt therapy with parenteral and topical vitamin A, protein supplementation, and a soft contact lens restored corneal integrity and prevented visual loss in one patient. Keratinization of the conjunctiva did not occur in either patient. Patients with severe protein deficiency may develop keratomalacia in the absence of a severely decreased serum level of vitamin A.

Keratomalacia

Xerophthalmia and keratomalacia are public health problems of great magnitude which are usually associated with multiple vitamin and protein deficiencies. The authors report the case of a 27-year-old commune member who subjected herself to a bizarre protein and vitamin deficient diet for many months. This ultimately produced nyctalopia, xerophthalmia and keratomalacia with bilateral corneal perforation. Despite therapy, she remained comatose and expired shortly after admission. Ocular pathological changes included bilateral corneal melting with prolapse of intraocular contents, conjunctival epidermidalization, goblet cell atrophy and thinning of the outer nuclear layer of the retina. It is noted that ocular findings in pure avitaminosis A produced experimentalyy include epithelial atrophy followed by keratinization.

Collagenase and other proteinases in the cornea of the retinol-deficient rat

1. Enzymes that may contribute to liquefaction of the cornea in retinol-deficient animals and in man have been studied using rat cornea. The established technique of culturing tissue fragments and determining the activity of collagenase (EC 3-4-24-3) and other enzymes in the medium after different periods of culture was used. 2. A collagenolytic system was detected in the media from cultures of rat corneas. This system probably consists of at least two enzymes, a collagenase and a neutral proteinase. 3. Both proteolytic and specific collagenolytic activity were greater in media from retinol-deficient rat corneas. The hydroxyproline level increased in parallel with the increase in enzyme activity. 4. In the final stages of retinol deficiency the cornea is invaded by granulocytes and other cells of the blood and we suggest that destruction of cornea collagen may be due largely to the activity of the enzymes from these cells.

The role of retinol-binding protein in protein-calorie malnutrition

Plasma RBP is decreased to 1.62 mg plus or minus 0.71/100 ml, or 31.1 percent of normal, in the acute stage of kwashiorkor. RBP doubles its plasma level after 1 wk and triples after 2 wk of appropriate refeeding. The return to normal of RPB runs in close parallel with prealbumin (PA), implying that both components remain bound by 1:1 molar ratio in the PA-RBP complex. Low values recorded on admission for RBP seem to be the result of reduced liver biosynthesis. On the other hand, a high correlation persists between RBP and retinol plasma level along the successive steps of clinical recovery, suggesting that RBP acts as the limiting factor for retinol transport.