The role of liver in HDL metabolism, especially proapolipoprotein A-I metabolism

In present study，我们估计TCA assay to quantitate proapolipoprotein A-l converting activity （PAC activity）examined serum PAC activity from patients with various liver diseases and lipoproteindisorders.Human hepatoblastoma cell line, Hep G2were grown in near confluent monolayer culture and labeled with [<@D13@>D1H] phenylalanine for 12h.[< D13@>D3H] labeled proapolipoprotein A-l (proapo A-l) was purified from the culturemedia byimmunoaffinity purification using anti-apo A-l lgG Sepharose 4b column and then further purified bypreparative sd -polyacrylamide gel electrophoresis. Radiolabeled proapo a -l as a substrate wasincubated with serum for 24h at 37c, then mixed for 1h at room temperature with an equal volume10% TCA. PAC activity was calculated from the difference between radioactivities in the TCAsupernatant incubated with and without EDTA，and expressed the radioactivity/24h/ml serum.In normal control，serum PAC activity was calculated 7567 773dpm/24h…More /ml serum. Whereas in liver cirrhosis，这是一个典型的控制和其他规定3352 1272的显著ficantly lower than in normal control and was calculated 3352 1272贪污,使用hypertriglyceridemia had significantly high PAC activity at the level of 10530 3157. A有意义的反向correlation was observed between PAC activity and the ratio of proapo -l toapo a -l in serum. And serum PAC activity gave a good positive correlation with serum apo a -l Andtriglyceride,but no correlation were found between this activity and serum chole-sterol and HDL-cholesterol.Wehave demonstrated the TCA assay should be possible to quantitate PAC activity and shown thatpatients with liver cirrhosis had relative low this activity and with triglyceridemia had highactivity. Although the implications of the present results have not be made clear，这是必要的，以measure PAC activity in a variety of lipoprotein disorders. And thereby we willgain insights about the function of this enzyme in the lipoprotein metabolism. Less

In present study, we established the TCA assay to quantitate proapolipoprotein A-l converting activity (PAC activity) and examined serum PAC activity from patients with various liver diseases and lipoprotein disorders.Human hepatoblastoma cell line, Hep G2, were grown in near confluent monolayer culture and labeled with [<@D13@>D1H] phenylalanine for 12h. [<@D13@>D3H] labeled proapolipoprotein A-l (proapo A-l) was purified from the culturemedia by immunoaffinity purification using anti-apo A-l lgG Sepharose 4B column and then further purified by preparative SDS-polyacrylamide gel electrophoresis. Radiolabeled proapo A-l as a substrate was incubated with serum for 24h at 37゜C and then mixed for 1h at room temperature with an equal volume of 10% TCA. PAC activity was calculated from the difference between radioactivities in the TCA supernatant incubated with and without EDTA, and expressed the radioactivity/24h/ml serum.In normal control, serum PAC activity was calculated 7567 773dpm/24h … More /ml serum. Whereas in liver cirrhosis, it was significantly lower than that in normal control and was calculated 3352 1272. On the other hand, patients with hypertriglyceridemia had significantly high PAC activity at the level of 10530 3157. A significant inverse correlation was observed between PAC activity and the ratio of proapo A-l to apo A-l in serum. And serum PAC activity gave a good positive correlation with serum APO A-l and triglyceride, but no correlation were found between this activity and serum chole-sterol and HDL-cholesterol.We have demonstrated that the TCA assay should be possible to quantitate PAC activity and shown that patients with liver cirrhosis had relative low this activity and with triglyceridemia had high activity. Although the implications of the present results have not ever be made clear, it is necessary to measure PAC activity in a variety of lipoprotein disorders. And thereby we will gain insights about the function of this enzyme in the lipoprotein metabolism. Less