View clinical trials related to Night Blindness.
Filter by:Guatemala has enforced mandatory fortification of sugar with vitamin A (VA) since June 1974 and has led to a highly successful reduction in VA deficiency and associated disease. However, Ribaya-Mercado et al. 2014, estimated the biological impact of sugar fortified with retinyl palmitate that there may be a risk of chronic excess intake of preformed VA associated with programs of mass fortification. A recent food consumption survey in two departments in Guatemala found the average daily sugar intake in children under the age of two who aren´t being breastfed is 30.3 g, which translates into a daily intake of 272 μg of retinol (almost the full estimated average requirement (EAR) for that age group). Since data from the second National Survey on Micronutrients suggest a risk of VA toxicity, it is important to determine the levels of hepatic VA directly in corpses of individuals, of all ages, who have died of non-metabolic causes. Due to this, the investigators propose to assess liver and bone VA levels in combination with gene expression, histopathology and biochemical analyses, to elicit indications of hypervitaminosis A in Guatemala.
The combatant is likely to carry out missions any time, any place, day or night. The very strong degradation of natural vision performance in these conditions justifies the use of visual replacement means, based on optronic sensors whose sensitivity is more adapted to these luminous environments than that of the human eye. The duration and repetition of missions carried out with night vision sensors lead to visual complaints from users. The literature on night vision binoculars adjustment states that a binocular adjustment of the equipment provides more convex settings. The latter would then limit the strain on the accommodative component, which is one of the possible sources of operator visual fatigue. In order to allow a more appropriate adjustment, it is proposed to rely on a measurement of the refraction (optical defect of the eye) of each operator. Like binocular adjustments, binocular refractive methods would limit accommodative stimulation and thus visual fatigue. However, these methods are little used in favour of conventional methods. It is therefore necessary to evaluate the interest of binocular refraction for the adjustment of night vision binoculars. The purpose of this study is to compare refraction measurements by procedure in adult subjects free of ophthalmological disorders.
Since no quantitative information currently exists on how effectively the pro-vitamin A carotenoid (pVAC) β-cryptoxanthin (βCX) is converted to vitamin A (VA) in humans, this proof of principle study aims to compare the efficacy of both βCX and β-carotene (βC) to yield VA from biofortified maize. This data is critical before the breeding strategy for biofortified maize is directed towards high βCX-containing varieties in order to reduce VA deficiency in low-income countries.
The WHO recommended intermittent iron supplementation as a strategy for prevention of anemia and iron deficiency among school age children. Several aspects of cognitive development, co-supplementation with other micronutrients, severe adverse events especially in the context of malaria were missing. The investigators will evaluate the effectiveness of intermittent iron and vitamin A supplementation on cognitive development and anemia and iron status of Rural Ethiopian school children.
The prevalence of vitamin A deficiency was found high in children with sepsis. Whether those patients will benefit from the vitamin A supplementation is unknown.
Women of reproductive age had their vitamin A stores estimated by retinol isotope dilution and then were given vitamin A supplements near the US vitamin A RDA or placebo for 42(USA) or 60 (Indonesia) days, after which retinol isotope dilution was repeated and the change in vitamin A stores was determined in each group to estimate how much vitamin A is needed to maintain nutrient balance in these women.
Vitamin A (VA) and vitamin E (VE) are fat-soluble vitamins and indispensable substances in life activities. VA plays an important role in visual function, normal formation and development of epithelial cells, development and growth of bones, immune function and reproductive health. VA is of great significancCe for the growth and development of embryonic cells, especially for the development of fetal vertebrae, spinal cord, limbs, heart, eyes and ears. The lack of maternal VA will lead to the stunted development of fetal organs and tissues, and even fetal developmental malformation. In addition, VA has a protective effect on neonatal lung maturation.VA deficiency can cause the decrease in the activity of enzymes needed to catalyze the formation of progesterone precursors in pregnant women, reduce the production of steroids in adrenal glands, gonads and placenta, and seriously affect the functions of multiple organs such as heart, liver and skeletal muscle in pregnant women. VE, also known as tocopherol, has non-enzymatic antioxidant function, and maintains the balance of REDOX reaction in vivo by efficiently removing free radicals generated by lipid peroxidation.VE can increase the synthesis of nitric oxide (NO) in endothelial cells and improve vascular endothelial function. Long-term administration of VE can improve the impaired endothelium-dependent vasodilatory function in patients.VE can promote sex hormone secretion, improve fertility and prevent abortion. Pregnancy women the body's metabolism, increases produce free radicals, lipid peroxidation, low levels of VE will result in the accumulation of excess free radicals, cause the placenta aging, vascular endothelial damage, increase the risk of the occurrence of PHI and adverse outcome rate, as well as the membranes of cell membrane damage, increase the risk of premature rupture of membranes. Gestational hypertension is a group of diseases with both pregnancy and elevated blood pressure, and is the main cause of increased maternal and perinatal mortality, mainly including gestational hypertension, preeclampsia PE, and eclampsia, as well as chronic hypertension with preeclampsia and chronic hypertension with pregnancy. The cause of PE is unknown, but studies have found that it may be related to insufficient recast of spiral uterine arterioles, excessive activation of inflammatory immune system, damage of vascular endothelial cells, genetic factors, nutritional deficiency and insulin resistance. Recent studies have found that free radical oxidative damage may also be one of the main reasons for the occurrence and development of PE. PE occurs, the placenta bed vasospasm, ischemia, angiogenesis blocking and endothelial atherosclerotic changes, local immune cell activity, make produce free radicals increases, interfere with the vascular endothelial cell function, reduce vascular relaxation material synthesis, and shrink blood vessels increase material synthesis, promote vascular spasm, platelet condensed state is changed, thus appeared a series of PE. Previous studies have shown that oxygen free radicals and lipid peroxides are increased in PHI patients, while the levels of VA and VE are closely related to the antioxidant capacity of the body, and their lack can lead to the imbalance of the homeostasis of redox reaction in multi-tissue cells in the body. Since both VA and VE belong to fat-soluble vitamins and are widely distributed in daily food, whether their effects on the occurrence and development of PE are independent or combined will be a question for us to explore. Therefore, this study intends to evaluate the correlation between VA, VE and VA+VE and PE occurrence through multi-center clinical studies, and explore and summarize the feasibility of VA and VE in PE adjuvant treatment.
Vitamins A, D, and E play important roles in humans, such as vision function, immune function, bone metabolism, cell growth and differentiation and oxidation resistance. Deficiencies in these vitamins will result in a high prevalence of cardiovascular disease, infection, bone diseases, etc. Preterm infants, especially very low birth weight infants, are at risk of vitamin deficiency. Intravenous perfusion is the most common and widely used method to supply vitamins for the specific population in early life. However, the current dose of vitamin supplied by intravenous perfusion whether can meet the need of growth and development is not sure and the appropriate dose for preterm infants is still uncertain. The purpose of this study is to investigate whether current dose of fat-soluble vitamin supplementation is enough for very low birth weight infants, the safety of high dose of fat-soluble vitamin supplementation, and compare the differences of prevalence of common complications, such as bronchopulmonary dysplasia, patent ductus arteriosus, sepsis, anemia, and neural development between these two groups.
Breast milk is the best food during the first 6mo of life because it offers multiple benefits for the mother-infant pair. An inadequate maternal diet during pregnancy can lead to excess weight gain, leading to negative health consequences for the dyad. In Mexico, an excess of body weight coexists with micronutrient deficiencies (double burden of malnutrition). Low vitamin A concentration has been observed in northwest Mexico, which can affect the human milk composition and increase the risk of VAD in breastfed babies. An individualized dietary intervention in the lactating woman will reduce body weight and improve vitamin A status. The objective is to assess the effect of an individualized dietary intervention during 3 months postpartum on body composition and vitamin A status of lactating women.
This study establishes the safety and efficacy of vit A supplementation doses (3000 and 6000 IU/d) over 8 weeks in children with SCD-SS, ages 9 and older and test the impact of vit A supplementation on key functional and clinical outcomes. Additionally, vitamin A status is assessed in healthy children ages 9 and older to compare to subjects with SCD-SS.