Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0042875 (vitamin E deficiency)
 916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lipofuscin, age pigment, is a dark pigment with a strong autofluorescence seen with increasing frequency with advancing age in the cytoplasm of postmitotic cells. By bright-field light microscopy lipofuscin appears as irregular yellow to brown granules ranging in size from 1-2 nm in diameter. The fluorescent spectra of lipofuscin in situ generally show excitation maxima at about 360 nm and a yellowish emission maxima at 540-650 nm. Ultrastructurally the granules, localized in residual body-type lysosomes, are extremely heterogeneous and vary from one cell type to another, and frequently within a single cell. The pigment granules usually contain numerous liquid droplets embedded in an electron-dense matrix. The granules stain positively for neutral lipids but are not soluble in polar or non-polar lipid solvents. Lipofuscin contains about 50 percent by weight of proteinaceous substances, a lesser fraction of lipid-like material, and probably less than one percent by weight fluorophore(s); it is enriched in metals such as Al, Cu, and Fe, and in dolichols. Free radical reactions and the proteolytic system are implicated in lipopigment formation. Thus the rate of lipopigment formation is increased by vitamin E deficiency and by increased intake of polyunsaturated fatty acids as well as by protease inhibitors such as leupeptin. Free radical reactions and proteolysis are involved in the continual turnover of cellular components. Cellular damage from free radical reactions, and others such as hydrolysis, has been present since the beginning of life. The evolution of more complex cells necessitated development of defenses - DNA repair processes, antioxidants, etc. - against damaging reactions as well as the removal and replacement of altered parts, and of those no longer needed by the cells. Proteins "marked" for disposal by oxidation damage, or other means such as conjugation with ubiquitin, are apparently rendered more hydrophobic so that they are "recognized" for degradation by the lysosomes and the proteinases and peptidases of the cytosol and mitochondria. Oxidatively altered lipids are removed by enzymes such as phospholipase A2. The products of the degradation processes are reused by the cells. Normally the recycling of damaged components works extremely well. There may be some slow slippage with advancing age as the rate of free radical damage increases while protease activity decreases. As a result a gradually increasing fraction of lysosomal "food" may be converted to non-digestible forms, lipofuscin, before it can be broken down to reusable components. Ceroid is apparently formed when the disposal system is "overloaded" or impaired.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Lipofuscin and ceroid formation: the cellular recycling system. 248 57

The efficiency of alpha-tocopherol as a 7-etoxycumarine deethylase protector in rat liver microsomes damaged by phospholipase A2 at various levels of vitamin E was studied. No selective damage of cytochrome P-450 isoforms possessing a catalytic activity towards 7-etoxycumarine under vitamin E deficiency was observed. Phospholipase A2 decreased the deethylase activity of cytochrome P-450, the efficiency of the damaging action being dependent on vitamin E content in the liver. Exogenous alpha-tocopherol exerts an antiphospholipase effect and protects 7-etoxycumarine deethylase; the protective action is inversely proportional to vitamin E level in the liver. Under normal conditions the damaging effect of phospholipase A2 on cytochrome P-450 is mainly provided for by lysophospholipids, while under vitamin E deficiency both lysophospholipids and free fatty acids exert a damaging action. A possible mechanism of the stabilizing effect of alpha-tocopherol may consist in the interaction of the chromanol nucleus in the vitamin E molecyule both with lysophospholipids and with free fatty acids.
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PMID:[Non-antioxidative mechanism of cytochrome P-450 stabilization by alpha-tocopherol: the effectiveness in avitaminosis E]. 349 Feb 81

One of the classical vitamin E deficiency syndromes is nutritional encephalomalacia in broiler chicken. Subject of this study was the influence of dietary fatty acids and vitamin E on phospholipase A2 and alpha-tocopherol concentration in liver, cerebrum and affected cerebellum posthatching. Therefore, chicks were fed either oleic, linoleic or linolenic acid rich fats together with 5, 25, or 125 ppm vitamin E. At the end of 0, 1, 2 and 3 weeks the tocopherol content and phospholipase A2 activity of liver, cerebrum and cerebellum were determined. Dietary fatty acids did not influence tissue alpha-tocopherol and phospholipase A2. In the vitamin E-deficient cerebellum the enzyme activity of cytosolic phospholipase A2 was increased. Due to its low content of vitamin E the cerebellum is the most susceptible tissue to oxidative stress during vitamin E deficiency.
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PMID:Alpha-tocopherol and phospholipase A2 in liver and brain of chicks posthatching: the influence of dietary fat and vitamin E. 858

Vitamin E is the primary lipophilic antioxidant in mammals. Lack of vitamin E may lead to an increase of cytotoxic phospholipid-peroxidation products (PL-Ox). However, we could previously show that alimentary vitamin E-depletion in rats did not change the concentrations of dienes, hydroperoxides, and platelet-activating factor-related oxidation products in alveolar type II cells (TII cells). We hypothesized that vitamin E deficiency increases the activity of enzymes involved in the degradation of PL-Ox. Degradation of PL-Ox may be catalyzed by phospholipase A2, PAF-acetylhydrolase, or peroxiredoxins (Prx's). Alimentary vitamin E deficiency in rats increased the expression of Prx-1 at the mRNA and protein levels and the formation of Prx-SO3, but it did not change the expression of Prx-6 or the activity of phospholipase A2 and PAF-acetylhydrolase in TII cells. H2O2-induced oxidative stress in isolated TII cells activated protein kinase Calpha (PKCalpha) and increased the expression of Prx-1 and Prx-6. Inhibition of PKCalpha in isolated TII cells by long-time incubation with PMA inhibited PKCalpha and Prx-1 but not Prx-6. We concluded that the expression of Prx-1 and -6 is selectively regulated in TII cells; PKCalpha regulates the expression of Prx-1 but not Prx-6. Prx-6 expression may be closely linked to lipid peroxidation.
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PMID:Vitamin E differentially regulates the expression of peroxiredoxin-1 and -6 in alveolar type II cells. 1585 58