Effects of severe caloric restriction on the degree of sialylation of apoprotein C-III in obese women.

Alterations in the relative proportions of very low density lipoprotein (VLDL) apoprotein C-III (apoC-III) isoforms have been previously observed under various dietary and metabolic states. This study was designed to evaluate the effects of a very high caloric restriction on plasma triglycerides and on the relative proportions of VLDL apoprotein C-II (apoC-II) and apoC-III isoforms in obese subjects. VLDL were isolated by preparative ultra-centrifugation from 12 obese women. ApoC-II and apoC-III subspecies were separated by analytical ultrathin-layer isoelectrofocusing. The mean body weight decreased significantly from 96.2 +/- 8.7 to 90.6 +/- 7.6 kg (p less than 0.01). Mean total and VLDL triglycerides did not vary significantly. Apoprotein C-III2 (apoC-III2) as percentage of total apoprotein C increased (p less than 0.01) and apoprotein CIII0 (apoC-III0) decreased (p less than 0.01). Apoprotein C-III1 (apoC-III1) did not vary significantly. An inverse correlation was found between the percentage variation of apoC-III2 and that of apoC-III1 (r = -0.94; p less than 0.01). The variations of apoC-III2 correlated positively (r = 0.83; p less than 0.01), while those of apoC-III1 correlated inversely (r = -0.65, p less than 0.025) with the changes of VLDL triglycerides. The apoC-III1 to apoC-III2 ratio as well as the apoC-III0 to apoC-III2 and apo C-III1 ratios decreased after diet (p from less than 0.01 to less than 0.001). Total apoC-III as well as apoC-III2 and apoC-III1 to apoC-II ratios did not vary.(ABSTRACT TRUNCATED AT 250 WORDS)