Preparation of a stable fresh frozen primary lipoprotein[a] (Lp[a]) standard.

LP[a] is one of the most atherogenic lipoproteins consisting of an LDL-like core particle and a covalently linked glycoprotein of variable size. Due to its structural features, its heterogeneity and instability, there are great difficulties in standardizing quantitative immunochemical Lp[a] assays. One particular problem is the preparation of a pure primary standard, which is sufficiently stable to be used for value assignment of secondary reference material.

Mapping of antigenic determinants of purified, lipid-free human serum amyloid A proteins.

Serum amyloid A (SAA) is the major apolipoprotein of high-density lipoproteins (HDL) present during the acute-phase reaction. To map specific epitopes on purified, lipid-free SAA, sequence-specific antibodies raised against synthetic peptides corresponding to amino acid residues 1-17, 14-30, 27-44, 40-63, 59-72, 68-84, 79-94 and 89-104 of human SAA1 were studied. Using the indirect sandwich dissociation-enhanced lanthanide fluorescence immunoassay, antibodies raised against epitopes comprising residues 1-17, 14-30, 40-63 and 79-94 failed to recognize the corresponding domains on isolated human SAA1/SAA2 or a mixture of both isoforms, indicating that these epitopes are masked, apparently because of specific folding and/or self-aggregation (dimerization).

Quantification of lipoprotein lipase (LPL) by dissociation-enhanced lanthanide fluorescence immunoassay. Comparison of immunoreactivity of LPL mass and enzyme activity of LPL.

Lipoprotein lipase (LPL) hydrolyses triglycerides in chylomicrons and in very low density lipoproteins. In this study, a new sensitive enzyme immunoassay, the dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA), for the quantification of immunoreactive LPL mass in biological specimens was developed. In the indirect sandwich DELFIA assay polyclonal anti-human or anti-bovine LPL IgGs were used as capture antibodies, monoclonal antibody (mAb) 5D2 and Eu(3+)-labelled goat anti-mouse IgG were used as detection antibodies.

Quantification and mapping of antigenic determinants of serum amyloid A (SAA) protein utilizing sequence-specific immunoglobulins and Eu3+ as a specific probe for time-resolved fluorometric immunoassay.

Serum amyloid A (SAA) protein, the most prominent amongst acute-phase proteins, is the specific precursor protein of secondary reactive amyloidosis. The fact that SAA once released into the circulation as a 'free' protein rapidly associates with lipoproteins of the high-density range indicates a specific role in lipoprotein metabolism. In this study a new sensitive assay for quantification of human SAA protein in biological specimens using affinity-purified polyclonal antibodies and Eu3+ as a specific probe for time-resolved fluorometric immunoassay is presented.

Lysine modification of LDL or lipoprotein(a) by 4-hydroxynonenal or malondialdehyde decreases platelet serotonin secretion without affecting platelet aggregability and eicosanoid formation.

The effects of lysine-modified atherogenic plasma lipoproteins, known to be constituents of human atherosclerotic plaques, were studied on platelet function in vitro. LDL and lipoprotein(a) [Lp(a)] modified with secondary breakdown products of lipid peroxidation (4-hydroxy-2,3-trans-nonenal [HNE] 0.1 to 10 mmol/L or malondialdehyde [MDA] 1 to 50 mmol/L) induced neither spontaneous platelet aggregation nor secretion of 5-hydroxytryptamine (5-HT) from platelet aminestorage granules.