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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidative stress which results from an imbalance between reactive oxygen species production and antioxidant defense mechanisms is now well recognized in hemodialysis (HD) patients and could be involved in dialysis-related pathologies such as accelerated atherosclerosis, amyloidosis and anemia. In order to evaluate the rationale for preventive intervention against oxidative damage during HD, we review the factors that are implied and may be responsible for the imbalance between pro- and antioxidative mechanisms. The inflammatory state mainly due to hemobioincompatibility of the dialysis system plays a critical role in the production of free oxygen radical species contributing by this way to worsen the prooxidant status of uremic patients. Two factors largely contribute to the stimulation of the NADPH oxidase: hemoreactivity of the membrane and trace amounts of endotoxins. The antioxidant system is severely impaired in uremic patients and gradually altered with the degree of renal failure. HD could further impair this antioxidant system mainly by losses of (a) hydrophilic unbound small-molecular-weight substances such as vitamin C, (b) trace elements and (c) enzyme-regulatory compounds. Two main axes may be proposed in order to prevent and/or to decrease oxidative stress in HD patients. One consists in improving the hemocompatibility of the dialysis system mainly by using a dialyzer with low hemoreactivity and ultrapure, sterile, nonpyrogenic dialysate. The other consists in supplementing the deficiency patients with antioxidants. This could be achieved by oral or perdialytic supplementation. Vitamin E could be bound on dialyzer membrane. Alternatively, hemolipodialysis consists in loading HD patients with vitamin C or E via an ancillary circuit made of vitamin E-rich liposomes. The presence of liposomes could also facilitate the removal of hydrophobic prooxidative substances.
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PMID:Why hemodialysis patients are in a prooxidant state? What could be done to correct the pro/antioxidant imbalance. 1085 22

The high frequency of chromosomal breaks in Fanconi anemia (FA) lymphocytes has been related to the increased oxidative damage shown by these cells. The effect of 100 microM DL-alpha-tocopherol (Vitamin E) on the level of chromosomal damage in mitosis was studied in lymphocytes from five FA patients and from age matched controls, both under basal conditions and when G2 repair was prevented by 2.5 mM caffeine (G2 unrepaired damage). In addition, the effect of this antioxidant on G2 duration and the efficiency of G2 repair was also evaluated in the sample. alpha-Tocopherol (AT) decreased the frequency of chromosomal damage (under basal and inhibited G2 repair conditions) and the duration of G2 in FA cells. This antioxidant protective effect, expressed as the decrease in chromatid breaks, was greater in FA cells (50.8%) than in controls (25%). The efficiency of the G2 repair process (G2 R rate) defined as the ratio between the percentage of chromatid breaks repaired in G2 and the duration of this cell cycle phase was lesser in FA cells (10.6) than in controls (22.6). AT treatment slightly increased this G2 R rate, both in FA cells and controls. These results suggest that an increased oxidative damage and a lower G2 repair rate may be simultaneously involved in the high frequency of chromatid damage detected in FA cells.
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PMID:Fanconi anemia lymphocytes: effect of DL-alpha-tocopherol (Vitamin E) on chromatid breaks and on G2 repair efficiency. 1110 2

Nutritional status directly affects immune competence; therefore, dietary supplements can be beneficial. Vitamin A, a fat-soluble nutrient obtained exogenously from animal protein or synthesized endogenously from carotenoids, is important in vision, epithelial tissue maintenance, reproduction, and growth. It is also an antioxidant, and can interfere with HIV-related oxidative destruction. Vitamin C, a water-soluble antioxidant important in hydroxylation reactions and required by erythrocytes for retrieving stored iron, can suppress HIV in vitro. However, this requires long-term administration, and its effect ceases upon termination of treatment. Vitamin E, fat-soluble tocopherols, can be found in plants, vegetable oils, milk, eggs, fish, meats, and cereals. A potent antioxidant because of its electron-donating ability, vitamin E reduces HIV replication. Deficiency reduces inhibition of tumor necrosis factor alpha (TNF-a) and protein kinase C, therefore limiting immunocompetence. Additionally, damaging side effects of AZT, normally reversed or minimized by vitamin E, may induce low leukocyte counts and anemia. Vitamin E acts synergistically with selenium, another antioxidant, to block the rate of lipid peroxidation. Its administration may reduce diarrhea, cramping, and weight loss, and may improve epithelial conditions and reduce the frequency of illness. N-acetylcysteine (NAC), a sulfur-containing amino acid, inhibits HIV replication by raising serum glutathione levels through inhibition of TNF-a. Finally, HIV-infected patients should consider gluten-free diets during times of acute gastric distress.
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PMID:Nutrition and HIV. 1136 99

Iron supplementation is essential for adequate response to recombinant human erythropoietin (rHuEPO) or darbepoetin alfa. Oral iron therapy is often ineffective as the quantity of iron absorbed after oral intake may be insufficient to keep pace with the demands of rHuEPO-stimulated erythropoiesis in patients with end-stage renal disease (ESRD). Currently available i.v. iron preparations include dextran, iron gluconate, and iron sucrose. As rare, but serious, adverse reactions to i.v. iron dextran have been reported, alternative preparations may be preferred. Careful monitoring of iron parameters is required to avoid the effects of over-treatment. Renal anaemia and iron therapy are associated with oxidative stress, leading to a shortening of the lifespan of red blood cells (RBC) and resistance to rHuEPO. rHuEPO therapy may also enhance oxidative stress on RBC. Oxidative stress can be attenuated or prevented by supplementation with vitamin E or melatonin. Vitamin E therapy has also been shown to have a rHuEPO-sparing effect. Disturbances of carnitine metabolism may contribute to the development of renal anaemia in ESRD patients. Oral or i.v. L-carnitine therapy results in an increase in haematocrit and a significant decrease in rHuEPO requirement in HD patients. As yet, there is no general recommendation for L-carnitine supplementation for ESRD patients with renal anaemia.
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PMID:Adjunctive therapy in anaemia management. 1209 9

This review of the nutritional needs of very low birth weight infants (VLBW) concluded that vitamin supplementation was indicated for vitamins A, D, C, and folic acid. With breast feeding or other circumstances, there may be marginal needs for vitamin E, K, B1, B2, and B6. Supplementation of VLBW depends upon the gestation age, which is related to the placental transfer and body stores at birth, and vitamin content of breast milk or formula (feeds), and volume and micronutrient composition of feeds. The infant's vitamin stores at birth are dependent on the nutritional status of the mother, particularly lipid soluble vitamins, which have been found to be higher in fetal cord blood than in maternal blood. The exception is B6, which crosses the placental barrier with difficulty. Preterm infants and infants of undernourished mothers usually have reduced levels of water soluble vitamins at birth. There is some variability in nutrients of feeds. Breast milk, for instance, has lower levels of vitamins D and K than recommended levels. Needs will also very with the presence of particular nutrients. For example, B6 requirements will vary with protein intake. Vitamin E requirements will depend on the amount of linoleic acid or polyunsaturated fatty acids in the diet. Tryptophan in the presence of B6 allows the synthesis of niacin. Volume of feeding affects nutritional needs. The recommended daily allowance (RDA) of specific nutrients for an infant up to 6 month of age and weighing 3-8 kg requires consumption of 500-1000 ml of breast milk or formula per day. A full term infant can receive sufficient nutrients with 450-750 ml, but below 400 would result in a deficit of vitamins. Unfortunately, the volume of feeds for VLBWs is too low in the first two weeks of life or until the body weight of 2000 g is reached; thus supplementation was recommended. Late anemia due to vitamin E deficiency may be prevented when the alpha tocopherol per gram of polyunsaturated fatty acids ratio is equal to or higher than the recommended levels. When intake of vitamin K at birth is insufficient, deficiencies may appear later; the recommendation was .2 to 1.0 mg at birth as a preventive regimen. Vitamin D was also recommended for both breast and formula fed infants. Pyridoxine/ g protein intake, folic acid, and vitamin C should be provided VLBW infants as indicated.
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PMID:Vitamin requirements of very low birth weight infants: a review. 1231 6

Vitamin E and carotenoids are known to act as antioxidants both in vitro and in vivo. In this review we present a series of studies in healthy subjects and in patients who exhibit either acute or chronic oxidative stress. In the EU-Commission funded VITAGE project we investigated the status and effects of vitamin E and carotenoids on oxidative stress in 300 healthy volunteers. Depletion studies limiting dietary vitamin E or carotenoid intake to approximately 25% of the dietary reference intakes and subsequent repletion by supplementation with either large doses of vitamin E or intermediate doses of carotenoids showed significant changes in ex vivo LDL oxidizability, total plasma peroxide concentrations and urinary 8-oxo-7,8-dihydro-2(')-deoxyguanosine excretion. Patients on chronic hemodialysis present with oxidative stress in the presence of normal vitamin E but impaired vitamin C status and, due to anemia, need to be treated with parenteral iron. We studied the effects of a single oral dose of vitamin E taken 6 h prior to intravenous infusion of 100 mg iron, which exceeded the iron-binding capacity of transferrin. Vitamin E significantly reduced and in combination with a single dose of vitamin C completely abrogated acute oxidative stress induced by the iron load. Patients with cystic fibrosis are exposed to chronic oxidative stress due to an overproduction of reactive oxygen species as a result of neutrophil-dominated lung inflammation and impaired antioxidant status. Biochemical vitamin E and carotenoid deficiencies could be fully corrected even in the presence of fat malabsorption using intermediate doses of either RRR alpha-tocopherol or all-rac alpha-tocopheryl acetate and water-miscible all-trans beta-carotene. Long-term supplementation reduced ex vivo LDL oxidizability, in vivo lipid peroxidation and lung inflammation.
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PMID:Effects of vitamin E and carotenoid status on oxidative stress in health and disease. Evidence obtained from human intervention studies. 1458 10

The analysis of vitamin and iron indexes of 95 children sufficiently supplied with vitamin C and vitamin B2 and carotenoids deficiency has been carried out. Vitamin E deficit takes place among anemic children (with decreased hemoglobin blood level) 2 fold more often than among healthy children. From another side, decreased hemoglobin blood level, erythrocyte quantity and erythrocyte indexes have been determined 1.7-2.4 fold more often in insufficiently supplied with vitamin E children. Tocopherols serum level had tendency to the decrease and vitamin E deficit took place 2 fold more frequently in children suffering from iron deficiency anemia that is with decreased hemoglobin and serum ferritin concentrations. Marked positive linear correlation between these iron indexes and vitamin E serum level has been revealed. These results give evidence concerning significant role of this vitamin in the body iron supplying. The results obtained give evidence for multi-deficient anemia presence among children, which are not always caused by iron deficit. High frequency of vitamin E and B group vitamins deficiency proves expediency of these vitamins inclusion in complex therapy of iron deficiency.
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PMID:[The connection between vitamin and iron status indexes of school-age children]. 1568 56

Vitamin E comprises a group of compounds possessing vitamin E activity. alpha-Tocopherol is the compound demonstrating the highest vitamin E activity, which is available both in its natural form as RRR-alpha-tocopherol isolated from plant sources, but more common as synthetically manufactured all-rac-alpha-tocopherol. Synthetic all-rac-alpha-tocopherol consists of a racemic mixture of all eight possible stereoisomers. Assessing the correct biological activity in form of bioavailability and biopotency has been a great challenge during many years as it is difficult to measure clinical endpoints in larger animals than rats and poultry. Thus, the biological effects in focus are resorption of fetuses, testicular degeneration, muscle dystrophy, anemia, encephalomalacia, and in recent years the influence of vitamin E on the immune system are the most important clinical markers of interest. For humans and animals, only different biomarkers or surrogate markers of bioactivity have been measured. In studies with rats, a good consistency between the classical resorption-gestation test and the bioavailability of the individual stereoisomers in fluids and tissues has been shown. For humans and other animals, only different biomarkers or surrogate markers of bioactivity have been measured, and due to the lack of good biological markers for bioactivities, bioavailability is often used as one of the surrogate markers for bioactivities with those limitations this must give. Therefore, a relatively simple analytical method, which allows analysis of the individual stereoisomers of alpha-tocopherol, is an important tool in order to quantify relative bioavailability of the individual stereoisomers. The analytical method presented here allows the quantification of total tocopherol content and composition by normal phase HPLC and subsequent separation of the stereoisomers of alpha-tocopherol as methyl ethers by chiral HPLC. Using this method, the alpha-tocopherol stereoisomers are separated into five peaks. The first peak consists of the four 2S isomers (SSS-, SSR-, SRR-, SRS-), the second peak consists of RSS-, the third peak consists of RRS-, the fourth peak consists of RRR-, and the fifth peak consists of RSR-alpha-tocopherol. The discussion on the bioavailability of RRR- and all-rac-alpha-tocopheryl acetate has primarily been based on human and animal studies using deuterium-labeled forms, whereby a higher biopotency of 2:1 (of RRR: all-rac) has been demonstrated, differing from the accepted biopotency ratio of 1.36:1. In agreement with previous studies, the 2S-forms exert very little importance for the vitamin E activity due to their limited bioavailability. We find notable differences between animal species with regard to the biodiscrimination between the 2R-forms. Especially, cows preferentially transfer RRR- alpha-tocopherol into the milk and blood system. The distribution of the stereoisomer forms varies from tissue to tissue, and in some cases, higher levels of the synthetic 2R-forms than of the RRR-form are obtained, for example, for rats. However, the biodiscrimination of the stereoisomers forms is influenced by other factors such as age, dietary levels, and time after dosage. More focus should be given on the bioactivity of the individual 2R-forms rather than just the comparison between RRR- and all-rac-alpha-tocopheryl acetate.
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PMID:Alpha-tocopherol stereoisomers. 1762 78

On the basis of preliminary data, this larger bi-institutional continuation trial evaluating the efficacy and safety of early iron supplementation in preterm infants calls attention to the levels of vitamin E, a marker of antioxidant activity, during iron treatment. A total of 116 preterm infants were randomly assigned to receive at 2 or 4 weeks of age ( N = 62, N = 54, respectively) 5 mg/kg/d of nonionic iron polymaltose complex concomitantly with a daily dose of 25 IU vitamin E (as dl-alpha-tocopherol acetate) from 2 weeks of age. Vitamin E (alpha-tocopherol) levels, iron, ferritin, hemoglobin concentration, and reticulocyte count were recorded from 2 to 8 weeks of age. The morbidities of prematurity associated with free radicals formation were also documented. A gradual increase of alpha-tocopherol levels within physiological range (0.8 to 3.5 mg/dL) was found in the 2-week and 4-week groups during the study period with no difference among the groups ( P > 0.05 for all comparisons). At 8 weeks of age, iron and ferritin levels, hemoglobin concentration, and reticulocyte count were higher in the 2-week group. No correlation was observed between timing of both iron and vitamin E supplement and hemolysis or morbidities associated with prematurity. Thus, treatment of iron with vitamin E supplement at 2 weeks of age is, in our experience, an efficacious and safe treatment for improving anemia in preterm infants.
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PMID:Vitamin E levels during early iron supplementation in preterm infants. 1926 37

Oxidative stress and resultant accumulation of advanced glycation end products (AGEs) are closely related to the development of cardiovascular disease, which is the major cause of death among end-stage renal disease patients. Several markers of oxidative stress, such as malondialdehyde, oxidized low-density lipoprotein, AGEs and 8-hydroxyde-oxyguanosine, are significantly elevated in circulating blood and/or tissue levels. Vitamin E is one of the scavengers opposed to oxidative stress and has been bonded to the dialyzer membrane surface to suppress oxidative stress related to hemodialysis itself. Vitamin E-coated dialyzers are widely used in Japan and several favorable clinical effects have been reported. Improved biocompatibility leads to decreased activation of circulating blood cells and these are related to reduced doses of heparin, improvement of anemia, and dose reduction in erythropoiesis-stimulating agents. Improvement of the cytokine network and immunological system is also suggested. It is expected that regression of atherosclerosis and slowed vascular calcification might occur parallel with reduction of oxidative stress by vitamin E-coated dialyzer. An improvement of endothelial function and dialysis hypotension during dialysis has also been reported. In small studies in Japan, improvement of nutritional state, insulin resistance and quality of life have been suggested. Although a larger scale control study will be needed, hemodialysis with vitamin E-coated membrane might become another powerful treatment modality other than hemodiafiltration.
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PMID:Markers and possible uremic toxins: Japanese experiences. 2093 33


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