Active clinical trials for "Night Blindness"

Minimal human data exist on actual liver vitamin A compared with blood biomarkers. One blood biomarker, the percent of total serum retinol (vitamin A) in the form of retinyl esters, has been suggested to diagnose hypervitaminosis A with cutoffs of 5% and 10%. In this study, investigators aim to compare total liver vitamin A reserves with the percent total serum retinol as retinyl esters to evaluate hypervitaminosis A using autopsy samples from US adults. Investigators also evaluate the sensitivity (the ability of the biomarker to correctly identify those with deficiency) and specificity (the ability of the biomarker to correctly identify those without deficiency) of serum retinol to determine vitamin A deficiency, variation of liver vitamin A concentration among lobes, and liver alpha retinyl ester concentrations, a cleavage product of alpha-carotene, a vitamin A precursor. To conduct the study, matched serum and liver samples were procured from 27 US adult cadavers (from donors age 49-101 years) and their vitamin A biomarkers were analyzed.

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.

The primary hypothesis is that introduction of food-to-food fortified products through a rural Hub-and-Spoke incubator system contributes to an improved food environment and availability of micronutrients to these communities. A secondary hypothesis is that the influence of the rural Spokes can serve to enhance rural food environments through creation of secondary rural spokes that disseminate improved food-to-food fortified products. The overall hypothesis is that a product designed with optimized nutritional characteristics, based on consumer preferences and leveraging local nutrient dense ingredients, can successfully deliver nutrition through sustainable market-driven approaches.

Vitamin A deficiency remains a major public health problem in developing country worldwide. Young Children are considered to be at greatest risk of deficiency. However, there is little information on the vitamin A requirement of Chinese children. In the present study, about 400 children aged between 4 and 9 years old in a kindergarten and an elementary school of Shiyan City were screened before admission by questionnaire and anthropometric measurement. The vitamin A status of children was assessed by serum vitamin A level, relative dosage reaction and stable-isotope dilution technique. At the same time, their dietary vitamin A intakes were estimated by weighted-food dietary survey. The dietary vitamin A requirement in young children was determined on the basis of dietary vitamin A intakes in Children with adequate vitamin A level.

The overall objective is to determine the impact of EED on zinc absorption and homeostasis, and its impact on the absorptive capacity of vitamin A absorption of young children (18-24 months of age) in an austere setting with high rates of diarrhea, stunting, and micro-nutrient deficiencies.

The overall hypotheses is that a product designed with optimized nutritional characteristics, based on consumer preferences and leveraging local nutrient dense ingredients, can successfully deliver nutrition through sustainable market-driven approaches. The objectives of this study will be 1) to assess the nutritional adequacy of Kenyan households with children and 2) to determine the market potential of a locally sourced and manufactured, blended fortified, cereal-based product for the improvement of micronutrient deficiencies among children aged 24-60 months. This study will simulate a market study, the investigators conducted a product launch, determined market potential based on sales, evaluated marketing strategy to increase market share, and modeled the nutritional contribution of FtFF/traditionally fortified product for iron, zinc, and vitamin A. The investigators expect to provide a throughout evaluation of a business-driven strategy (for profit, social enterprise) as a sustainable tool to decrease micronutrient deficiencies.

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.

To conduct a sub-regional micronutrient survey (SRMNS) assessing the prevalence of vitamin A, Zn, and Fe status in the country