Lipoprotein plasma levels

A correlation may be established between the concentration of oxidized lipids and the TEARS value, expressed as MDA equivalents, in uM units. Correction is due in some cases for the interference by dyes or other factors. For example, the presence of anthocyanins in red cabbage leaves or turbiditjf causes overestimation of lipid hydroperoxides in plant tissue by the TEARS method. TEARS was used to assert the level of endogenous peroxides in hypo- and hyperthyroidism, both conditions being characterized by low lipid and lipoprotein plasma levels and enhanced oxidative metabolism . In a procedure for determination of TEARS in edible oils, the sample is placed in a centrifuge at 12000 g before measuring at 532 nm (e = 1.56 x 10 M cm ) . A usual procedure for determination of TEARS in certain complex matrices involves steam distillation of the aldehydes responsible for the value, instead of extraction. In nitrite-cured meats, excess nitrite may cause nitrosation of MDA, thus interfering with distillation. To avoid this interference sulfanilamide is added, which is converted to a diazonium salt and... 

A class of important pharmacological compounds that are the most effective drugs for lowering plasma levels of low-density-lipoprotein (LDL)-cholesterol. 

Couture P, Otvos JD, Cupples LA, Wilson PW, Schaefer EJ, Ordovas JM. Association of the A-204C polymorphism in the cholesterol 7alpha-hydroxylase gene with variations in plasma low density lipoprotein cholesterol levels in the Framingham Offspring Study. J lipid Res 1999 40 1883-1889. 

Contrary to LDL, high-density lipoproteins (HDL) prevent atherosclerosis, and therefore, their plasma levels inversely correlate with the risk of developing coronary artery disease. HDL antiatherogenic activity is apparently due to the removal of cholesterol from peripheral tissues and its transport to the liver for excretion. In addition, HDL acts as antioxidants, inhibiting copper- or endothelial cell-induced LDL oxidation [180], It was found that HDL lipids are oxidized easier than LDL lipids by peroxyl radicals [181]. HDL also protects LDL by the reduction of cholesteryl ester hydroperoxides to corresponding hydroperoxides. During this process, HDL specific methionine residues in apolipoproteins AI and All are oxidized [182]. 

One type of hyperlipoproteinemia is characterized by elevated plasma levels of chylomicra, normal plasma levels of 3-lipoproteins, and the inability of any known drug to reduce lipoprotein levels. This is which of the following types of hyperlipoproteinemia ... 

G3. Garcia Frade, L. J., Alvarez, J. J., Rayo, I., Torrado, M. C., Lasuncion, M. A., Garcia Avello, A., Hernandez, A., and Marin, E., Fibrinolytic parameters and lipoprotein (a) levels in plasma of patients with coronary artery disease. Thromb. Res. 63, 407-418 (1991). 

L14. Leitersdorf, E., Friedlander, Y., Bard, J.-M., Fruchard, J.-C., Eisenberg, S., and Stein, Y., Diverse effect of ethnicity on plasma lipoprotein(a) levels in heterozygote patients with familial hypercholesterolemia. J. Lipid Res. 32, 1513-1519 (1991). 

Sundell, I. B., Nilsson, T. K., Hallmans, G., Hellsten, G., and Dahlen, G. H., Interrelationships between plasma levels of plasminogen activator inhibitor, tissue plasminogen activator, lipoprotein (a) and established cardiovascular risk factors in a North Swedish population. Atherosclerosis (Shannon, Irel.) 80, 9-16 (1989). 

Y2. Yamazaki, M., Asakura, H., Jokaji, H., Saito, M., Uotani, C., Kumabahiri, I., Morishita, E., Aoshima, K., Ikeda, T., and Marsuda, T., Plasma levels of lipoprotein(a) are elevated in patients with the antiphospholipid antibody syndrome. Thromb. Haemostasis 71, 424-427 (1994). 

Zairis MN, Ambrose JA, Manousakis SJ, et al. The impact of plasma levels of C-reactive protein, lipoprotein (a) and homocysteine on the long-term prognosis after successful coronary stenting the Global evaluation of new events and restenosis after stent implantation study. J Am Coll Cardiol 2002 40 1375-1382. 

Hagberg, J.M., Wilund, K.R., Ferrell, R.E. (2000) APOE gene and gene-environment effects on plasma lipoprotein-lipid levels. Physiol. Genomics, 4, 101-108. 

Lipoprotein (a) (abbreviated to Lp(a)) is a complex between LDL and apoprotein (a) that forms spontaneously in blood. Lp(a) is secreted by the liver but its function is unknown. A high plasma level of Lp(a) interferes with the conversion of plasminogen to plasmin, the role of which is to break down blood clots and even disperse small clots. 

Pharmacokinetics Ticlopidine is rapidly absorbed (more than 80%), with peak plasma levels occurring at approximately 2 hours after dosing, and is extensively metabolized. Administration after meals results in a 20% increase in the area under the plasma concentration-time curve (AUC). Ticlopidine displays nonlinear pharmacokinetics and clearance decreases markedly on repeated dosing. Ticlopidine binds reversibly (98%) to plasma proteins, mainly to serum albumin and lipoproteins. The binding to albumin and lipoproteins is nonsaturable over a wide concentration range. Ticlopidine also binds to alpha-1 acid glycoprotein at concentrations attained with the recommended dose, 15% or less in plasma is bound to this protein. 

Distribution - Largely outside the blood volume approximately 33% to 47% is in plasma, 4% to 9% in lymphocytes, 5% to 12% in granulocytes and 41% to 58% in erythrocytes. In plasma, approximately 90% is bound to proteins, primarily lipoproteins. Blood level monitoring is useful in patient management. 

The role of the antioxidant properties of vitamins C, E, and p-carotene in the prevention of cardiovascular disease has been the focus of several recent studies. Antioxidants reduce the oxidation of low-density lipoproteins, which may play a role in the prevention of atherosclerosis. However, an inverse relationship between the intake or plasma levels of these vitamins and the incidence of coronary heart disease has been found in only a few epidemiological studies. One study showed that antioxidants lowered the level of high-density lipoprotein 2 and interfered with the effects of lipid-altering therapies given at the same time. While many groups recommend a varied diet rich in fruits and vegetables for the prevention of coronary artery disease, empirical data do not exist to recommend antioxidant supplementation for the prevention of coronary disease. 

Substantial evidence indicates that high plasma levels of lipoprotein remnants and LDL are atherogenic, while high levels of HDL are atheroprotective. Therefore, the class of lipoproteins that is increased or decreased will determine the clinical feature of a patient. Besides the influence on atherosclerosis, high levels of chylomicrons lead to acute pancreatitis, while markedly decreased levels of VLDL and LDL lead to retinal and neurologic disease, probably due to vitamin E deficiency. 

The major biochemical changes observed are a striking depletion of ATP, impaired protein synthesis, defective incorporation of amino acids, and the appearance of RNA and proteins containing the ethyl rather than the methyl group. The plasma levels of triglycerides, cholesterol, lipoprotein, and phospholipid are all decreased. 

Unlike other lipoproteins, HDL particles are assembled outside of cells from lipids and proteins, some of which may be donated from chylomicrons (see Fig. 21-1) or other lipoprotein particles. HDL has a higher protein content than other lipoproteins and is more heterogeneous. The major HDL protein is apolipoprotein A-I, but many HDL particles also contain A-jj 205,208-210 ancj apolipoproteins A-IV, D, and E may also be present. A low plasma level of HDL cholesterol is associated with a high risk of atherosclerosis.205 207... 

Cholesterol biosynthesis is also controlled by the plasma levels of low-density lipoproteins, which we discuss in the context of lipoprotein metabolism later in this chapter. 

In contrast to MPO, eosinophil peroxidase (EPO) prefers to oxidize plasma level bromide (20-100 pM) to hypobromous acid (HOBr) and several biological targets are implicated, including nucleic acids and nucleosides (1480, 1482, 2376), proteins (1812, 1813, 2377, 2378), unsaturated fatty acids (2379), and low-density lipoprotein (2380, 2381). This EPO-dependent bromination is suggested to be involved in the pathogenesis of asthma (2382). Accordingly, both 3-bromotyrosine and 3,5-dibromotyrosine (1812,1813) are produced by EPO-induced bromination of tyrosine residues in lung tissue (1813, 2382). 

Heng, CK, Low, PS, Saha, N. Variations in the promoter region of the apolipoprotein A-I gene influence plasma lipoprotein(a) levels in Asian Indian neonates from Singapore. Pediatr. Res. 2001, 49 514—518. 

The characteristic effect of inhibitors of HMG-CoA reductase is a profound reduction in LDL cholesterol. The maximal doses of the most effective drugs in this class, simvastatin and atorvastatin, produce reductions by about half in the plasma levels of this atherogenic lipoprotein (Heinonen et al., 1996 Ose et al., 1998 Stein et al., 1998b). The full... 

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