[Lipoprotein examination in old hyperlipemic persons (author's transl)].

The fluorescence and thiobarbituric acid reaction of isolated beta lipoprotein (beta-LP) and alpha lipoprotein (alpha-LP) have been studied in young, old, and old hyperlipemic persons. Specific fluorescence showed no significant difference in the beta-LP of young and old individuals. However, the difference was signficant in the A:F 380:450 fluorescence (A= activation wavelength, F = fluorescence or emission wavelength) of the alpha-LP. On the effect of autooxidation the alpha-LP showed a significant increase in both the A:F 380:450 and the A:F 410:470 fluorescence. Absorption at 530 nm has been studied by the thiobarbituric acid (TBA) reaction. The malondialdehyde (MDA) content has been given as microgram/mg on the basis of the curve obtained by the known quantity of MDA. The MDA content of beta-LP in the young and old groups was less increased as compared to the substantial increase of alpha-LP. As opposed to results obtained in senile persons MDA increase of alpha-LP has been significant in old hyperlipemic individuals. In addition to the absorption peak at 530 nm, characteristic for MDA, a peak at 450 nm has been obtained by TBA. A yellow-brown substance associated with hyperlipemia did appear mainly in the protein fraction isolated from alpha-LP and has been named protein III. During oxidation in hydrochloric acid a yellow-brown substance appeared from protein III fraction and became unsoluble and dark brown in hyperlipemic persons. The substance was considered as a precursor of the atherofluorescent component (AFC) present in atherosclerotic aortas. The reaction in the alpha-LP, and particularly in its protein component, with MDA (originating from peroxidezed unsaturated fatty acids) leads to complexes which are, assumably, precursors of atheromatous lipid and calcium plaques.