Redox Biology of Blood

Antioxidants and Redox Signaling (Impact Factor: 7.41). 01/2005; 6(6):941-3. DOI: 10.1089/ars.2004.6.941
Source: PubMed
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    • "Hb is critical for life, providing cells with oxygen for their energy needs. However, outside of the confines of the erythrocytes (RBCs), Hb is highly toxic (Alayash, 2004). Its prosthetic group, haem, is lipophilic and readily intercalates into cell membranes to disrupt the lipid bilayers. "
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    ABSTRACT: Haptoglobin is an acute phase protein that scavenges haemoglobin in the event of intravascular or extravascular haemolysis. The protein exists in humans as three main phenotypes, Hp1-1, Hp2-2 and Hp2-1. Accumulated data on the protein's function has established its strong association with diseases that have inflammatory causes. These include parasitic (malaria), infectious (HIV, tuberculosis) and non-infectious diseases (diabetes, cardiovascular disease and obesity) among others. Phenotype-dependent poor disease outcomes have been linked with the Hp2-2 phenotype. The present review brings this association into perspective by looking at the functions of the protein and how defects in these functions associated with the Hp2 allele affect disease outcome. A model is provided to explain the mechanism, which appears to be largely immunomodulatory.
    Transactions of the Royal Society of Tropical Medicine and Hygiene 09/2008; 102(8):735-42. DOI:10.1016/j.trstmh.2008.04.010 · 1.84 Impact Factor
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    ABSTRACT: Transfusion of hemoglobin-based blood substitutes, designed for their plasma expansion and oxygen transport capabilities, has resulted in some major problems, such as organ dysfunction, during clinical trials. Experimental evidence demonstrates that these hemoglobins damage tissue by producing highly reactive oxygen species. Although cell-free hemoglobin may present a low risk to people with normal redox status, patients who are sick and have a poor antioxidant status may be at risk. Oxidative damage is particularly dangerous in the microcirculation because excess leakage of plasma components into the interstitium will disturb the fluid balance between blood and tissue and alter the kinetics of delivery of intravascularly injected drugs, and endogenous enzymes and hormones, to various tissues. In this review, the redox chemistry of hemoglobin-based blood substitutes is briefly described, and their effects on cultured endothelial cells, and on the exchange properties of the microvasculature, are discussed. Taking into account the possible mechanisms by which oxidative damage can occur, various methods to reduce the deleterious effects of blood substitutes in vivo are evaluated. Finally, several possible cell signaling pathways that are triggered in endothelial cells, in response to modified hemoglobins, are considered in terms of protecting microvascular function.
    Antioxidants and Redox Signaling 01/2005; 6(6):1019-30. DOI:10.1089/ars.2004.6.1019 · 7.41 Impact Factor
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    ABSTRACT: Haptoglobin (Hpt) is known to capture circulating free hemoglobin (Hb) and bind apolipoprotein (Apo) A-I or E. Here, we report that Hb can be tightly bound by most of Hpt molecules (TB-Hpt, 80%), whereas loosely bound by a minor part of them (LB-Hpt, 20%). LB-Hpt amount was significantly increased (over 60%) in patients with acute coronary syndrome. LB-Hpt bound ApoA-I and ApoE less efficiently than TB-Hpt (8- and 4-fold less, respectively) and did not affect their activity of stimulating the enzyme lecithin-cholesterol acyltransferase. LB-Hpt and TB-Hpt displayed comparable levels of nitrotyrosine residues, but differences in glycan chains. Changes in LB-Hpt level might be associated with changes in Hpt functions.
    Biological Chemistry 02/2011; 392(4):371-6. DOI:10.1515/BC.2011.033 · 3.27 Impact Factor
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