Red cell lipids

Phosphatidyl serines (or threonine) nh3 —ch2ch.cooh Widely distributed but in small amounts. Is a major component of brain and red cell lipids Usually isolated as salts with K+, Ca2+, Na+ or Mg2+... 

Isolated from Human Red Cells Lipids l(6) 391-398 (1966) CA 66 16634h... 

Phytanic acid of total red cell lipids may amount to 12% of total red cell fatty acids. Its concentration in the various lipid fractions of washed red cells varies the main portion is found in red cell phospholipids, although here cholesterol esters also contain phytanic acid. 

Morphologic abnormalities of erythrocytes stimulated studies on red cell lipids (Ways et al. 1963 Simon and Ways 1964 Fredrickson 1966) (see table 5). A normal total lipid content (Phillips and Roome 1959 Reed et al. 1960 ... 

Synthesis of glycogen, fatty acids, protein, and nucleic acids does not occur in the RBC however, some lipids (eg, cholesterol) in the red cell membrane can exchange with corresponding plasma lipids. 

The red blood cell must be able to squeeze through some tight spots in the microcirculation during its numerous passages around the body the sinusoids of the spleen are of special importance in this regard. For the red cell to be easily and reversibly deformable, its membrane must be both fluid and flexible it should also preserve its biconcave shape, since this facilitates gas exchange. Membrane lipids help determine membrane fluidity. Attached to the inner aspect of the membrane of the red blood cell are a number of peripheral cytoskeletal proteins (Table 52-6) that play important roles in respect to preserving shape and flexibility these will now be described. 

The new lipid occurred only in the plasma hpids of newborns and was not present in membrane hpids of red cell membranes or platelets. Total lipids were extracted from plasma and from red blood cell membranes and platelets. A total lipid profile was obtained by a three-directional PLC using silica gel plates and was developed consecutively in the following solvent mixtures (1) chloroform-methanol-concen-trated ammonium hydroxide (65 25 5, v/v), (2) chloroform-acetone-methanol-ace-tic acid-water (50 20 10 15 5, v/v), and (3) hexane-diethyl ether-acetic acid (80 20 1, v/v). Each spot was scraped off the plate a known amount of methyl heptadecanoate was added, followed by methylation and analysis by GC/MS. The accmate characterization of the new lipid was realized using NMR technique. 

The importance of vitamin E for maintenance of lipid integrity in vivo is emphasized by the fact that it is the only major lipid-soluble chain-breaking antioxidant found within plasma, red cells and tissue cells. Esterbauer etal. (1991) have shown that the oxidation resistance of LDL increases proportionately with a-tocopherol concentration. In patients with RA, synovial fluid concentrations of a-tocopherol are significantly lower relative to paired serum samples (Fairburn et al., 1992). The low level of vitamin E within the inflamed joint implies it is being consumed via its role in terminating lipid peroxidation and this will be discussed further in Section 3.3. 

Superoxide has a chemical half-life measured in microseconds, but in even this short time serious damage can be caused to all types of biological macromolecules. Peroxidation of membrane lipids could cause haemolysis but the oxidation of ferrous (Fe2+) to ferric (Fe3+) iron in haemoglobin due to free radical action is a more immediate cause for concern within the red cell (Figure 5.17). 

The interaction of an extrinsic membrane protein with a lipid bilayer can also be investigated by energy transfer. The interaction of cytochrome c has attracted much attention, and in an early study by Shaklai et al.(()5> the number of binding sites per red cell was determined. It was shown that an equation analogous to the Stem-Volmer relationship could be derived ... 

Satoh T, Kobayashi K, Sekiguchi S, et al. Characteristics of artificial red cells. Hemoglobin encapsulated in poly-lipid vesicles. ASAIO J 1992 38 M580. 

Evidence of a role of lipid peroxidation in the cellular toxicity of ozone has been obtained in in vitro studies in which human red cells were exposed to this oxidant gas. The possibility that lipid peroxidation is responsible for altered permeability of bacterial cell walls after ozone exposure was proposed by Scott and Lesher and has since been con-... 

More recently, B. Goldstein and McDonagh demonstrated that the native protein fluorescence (280-nm excitation, 330-nm emission) of red-cell membranes exposed in vitro to ozone at 1 ppm was a somewhat more sensitive indicator of ozone effect than other characteristics measured in the same em, including oxidation of cell-membrane sulfhydiyl groups, loss of acetylcholinesterase activity, and formation of lipid peroxide breakdown products. 

The possibility that pulmonary membranes are a primary site of ozone toxicity is suggested by a number of lines of evidence, most of which are indirect. These include observations that the membrane is the major site of ozone toxicity in plants and bacteria morphologic evidence of pulmonary membrane damage after ozone exposure in a number of studies and in vitro experiments with human red cells and artificial lipid membranes. 

Minor chromosomal abnormalities Inhibition of intracellular hydrolytic enzymes of alveolar macrophages increased fraction of polymorphonuclear leukocytes Alterations in blood, including red-cell membrane and enzyme changes and increased serum vitamin E and lipid peroxides Decreased lung DNA synthesis Decreased electric response of specific areas of brain with evoked-response technique... 

Alterations in blood, induding Man red-cell membrane and enzyme diaiiges and increased serum vitamin E and lipid peroxides... 

Q Yang, M Wallsten, P Lundahl. Immobilization of phospholipid vesicles and protein-lipid vesicles containing red cell membrane proteins on octyl derivatives of large-pore gels. Biochim Biophys Acta 938 243-256, 1988. 

Increased plasmalogen levels have not been observed. Erroneously low red cell levels can be encountered when the transmethylation process has not been completed. Breaking the ether lipid bond of the plasmalogens requires more energy than hydrolysis of the fatty acid esters. Evaluation of the plasmalogen levels should not be done after a blood transfusion. Donor erythrocytes will be present for up to 120 days following a transfusion. 

The lack of inhibition of lysis by catalase in the resealed vesicles prompted the proposal that the precursor which reacted with O to form the lytic species was not H2O2 but instead a lipid hydroperoxide the marked sensitization of the vesicles to the lytic effects of O , which prior photooxidation produced, was consistent with this proposal. Lysis of bovine red cells exposed to Oj , however, was inhibited by superoxide dismutase but not by catalase. ... 

The outer portion of the erythrocyte (red cell) is a very complex material composed of proteins, polysaccharides, and lipids, many of which are... 

PLASMA. The portion of the blood remaining after removal of the white and red cells and the platelets it differs from serum in that it contains fibrinogen, which induces clotting by conversion into fibrin by activity of the enzyme thrombin. Plasma is made up of more than 40 proteins and also contains acids, lipids, and metal ions. It is an amber, opalescent solution in which the proteins are in colloidal suspension and the solutes (electrolytes and nonelectrolytes) are either emulsified or in true solution. The proteins can be separated from each other and from the other solutes by nltrafiltration, nltracentrifugation, electrophoresis, and immuno-chemical techniques. See also Blood. 

Lead is widely destributed in the environment, especially in industrial and urban areas, and it is readily absorbed into the mammalian body where it exerts a number of undesirable physiological effects. Its most dramatic action is the inhibition of human red cell 5-aminolaevulinic acid dehydrase activity71), but it also depresses the activities of many enzymes having functionsl -SH groups. Attempts to remove lead from the body using agents such as dimercaptopropanol can result in the formation of lipid-soluble lead complexes that may be carried to the brain and exacerbate the effects of lead poisoning. 

Certain bioflavonoids may play a preventive role against cardiovascular diseases. Some citrus and other bioflavonoids have been demonstrated to reduce serum cholesterol levels and to affect fatty acid metabolism (70,71,72). The strong antiadhesive action on red cells and platelets of highly methoxylated flavones such as nobiletin, which also demonstrates antithrombogenic activity (73), indicates an important role in blood rheology and tissue perfusion. The antiadhesive action may indicate a preventive role in atherosclerosis since there is evidence that reduced perfusion of the vascular wall may interact with serum lipids to promote atherogenesis (74). 

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