5/2/2023 0 Comments Cardinal chains level 999 Urocanic acid is produced by the enzyme histidase in the stratum corneum and crucially protects the skin against harmful effects of UVB radiation. In its excess, the photo-exposed skin becomes more photosensitive. Production of kynurenic acid via the tryptophan-kynurenine-nicotinic acid pathway results from niacin deficiency. 2, 7, 8 Deficiency of these coenzymes can inhibit the repair of cell damage and affect tissues with high cellular turnover such as the brain, gastrointestinal tract and skin.Īlthough the pathogenesis of photosensitivity in pellagra is reasonably complex, Karthikeyan et al considered excess production of a photosensitiser, kynurenic acid and lack of urocanic acid. These two pyrimidine compounds are essential for oxidative phosphorylation and DNA regulation. NAD is involved in glycolysis and catabolism of protein and alcohol, whereas NADP acts as a hydrogen acceptor in the electron transport chain and functions in cholesterol and fatty acid synthesis. It is a water-soluble vitamin which is readily converted to nicotinamide-adenine-dinucleotide (NAD) and its phosphate (NADP) that are involved in metabolic reactions as hydrogen ion donors or acceptors. The deficient molecule, niacin (vitamin B3), refers to pyridine compounds, namely nicotinic acid and nicotinamide. 2, 7 It only became evident when Conrad Elvehjem and co-workers showed cure of pellagra with niacin when treating black tongue disease in dogs and pellagra-like condition in rats. He established nutritional factor as a cause of pellagra, but the deficient nutrient was still unrecognised. 2 Later in the 20th century an American public health doctor, Joseph Goldberger reported his study in which he experimented induction of pellagra in prison inmates by changing their diet and later correcting the condition by a diet supplemented with meat and vegetables. 6įor many years, pellagra was thought to be a form of leprosy and regarded as an insect-borne communicable disease until Casmiri Funk in 1912 proposed the vitamin hypothesis of pellagra as a diet-related disease. 5 In an impoverished population in central Malawi, an outbreak of pellagra was reported due to lack of niacin in the diet and niacin fortification was suggested as one way to stop pellagra in that setting. 4 Associated with the food insecurity triggered by the civil war, many cases of pellagra were reported during and after the war in Angola. Malfait et al described an epidemic of pellagra among Mozambican refugees after a change in protein supplements in their food rations in a refugee camp in Malawi. 2, 3 In low-income economies of Africa and Asia, pellagra remains a problem and upsurge of cases have occurred worsened by periods of inadequate food supplies. Instead, chronic alcoholism, malabsorption syndrome, anorexia nervosa and drug-induced niacin deficiency are the leading causes of pellagra in such settings. This is no longer the case in the developed world where it has been almost eradicated as a manifestation of primary nutritional deficiency. Previously nutritional deficiency was the leading and recognised cause of pellagra in the world. Pellagra was initially described by a Spanish Physician Gasper Casal. Pellagra is a clinical syndrome characterised by dermatitis, diarrhoea dementia and if untreated may result in death. This was not a formal systematic review, but we attempted, with this search, not to miss information about which we were not previously aware. We did not restrict searches by language. Eligible studies were case reports, journals, retrospective and prospective studies reported worldwide. We used Medline (NCBI, searched through EBSCO) search through Studynet access from the University of Hertfordshire, EMBASE, CINAHL, Google Scholar and PubMed. We searched relevant papers related to pellagra and its various causes. 1 An associated increase in pellagra has been seen. The World Health Organization (WHO) recommends isoniazid preventative therapy for routine use in patients receiving antiretroviral treatment in HIV in countries where latent tuberculosis is common.
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