Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Malabsorption of nutrients in cystic fibrosis (CF) has a multifactorial origin. The factors involved in malabsorption include malfunction of the exocrine pancreas and liver, bile acid metabolism, and disordered intestinal resorptive processes. Therapeutic measures presently employed are only partially effective. Improvement of fat malabsorption is attained by using a pancreatic enzyme supplement consisting of pH-sensitive, enteric-coated microspheres (microsphere preparations) that prevent enzyme degradation in the stomach and travel with the chyme to the small intestine. Microsphere preparations, however, do not improve bile salt deficiency. The detergent Tween-80, given orally to simulate bile salt activity, does not improve fat absorption. The mucus viscosity is probably enhanced in the intestinal epithelium of CF patients and can be decreased by N-acetylcysteine, which breaks down sulfide bonds. However, the addition of a high oral dose of this mucus solvent to pancreatin preparations does not improve fat absorption. Further studies on the disturbed intestinal resorptive mechanism seem warranted since recent investigations point to an abnormal chloride secretion as the primary defect in the intestinal epithelia of CF patients.
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PMID:Malabsorption in cystic fibrosis: mechanisms and treatment. 340 59

The intestinal mucosa is an important target of human immunodeficiency virus (HIV) infection. HIV virus induces CD4+ T cell loss and epithelial damage which results in increased intestinal permeability. The mechanisms involved in nutrient malabsorption and alterations of intestinal mucosal architecture are unknown. We previously demonstrated that HIV-1 transactivator factor (Tat) induces an enterotoxic effect on intestinal epithelial cells that could be responsible for HIV-associated diarrhea. Since oxidative stress is implicated in the pathogenesis and morbidity of HIV infection, we evaluated whether Tat induces apoptosis of human enterocytes through oxidative stress, and whether the antioxidant N-acetylcysteine (NAC) could prevent it. Caco-2 and HT29 cells or human intestinal mucosa specimens were exposed to Tat alone or combined with NAC. In an in-vitro cell model, Tat increased the generation of reactive oxygen species and decreased antioxidant defenses as judged by a reduction in catalase activity and a reduced (GSH)/oxidized (GSSG) glutathione ratio. Tat also induced cytochrome c release from mitochondria to cytosol, and caspase-3 activation. Rectal dialysis samples from HIV-infected patients were positive for the oxidative stress marker 8-hydroxy-2'-deoxyguanosine. GSH/GSSG imbalance and apoptosis occurred in jejunal specimens from HIV-positive patients at baseline and from HIV-negative specimens exposed to Tat. Experiments with neutralizing anti-Tat antibodies showed that these effects were direct and specific. Pre-treatment with NAC prevented Tat-induced apoptosis and restored the glutathione balance in both the in-vitro and the ex-vivo model. These findings indicate that oxidative stress is one of the mechanism involved in HIV-intestinal disease.
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PMID:The HIV-1 transactivator factor (Tat) induces enterocyte apoptosis through a redox-mediated mechanism. 2221 81