[Pool size and turnover of primary bile acids in hyperlipoproteinemias: different findings in type II and type IV hyperlipoproteinemias]

Reduced incidence of cardiovascular complications and mortality in hyperlipoproteinemia (HLP) with effective lipid correction. The Dresden HLP study

The influence of the efficacy of triglyceride and cholesterol correction on cardiovascular complications and mortality was analysed in a follow-up study with 260 patients with primary HLP (triglycerides before entry greater than 2.9 mmol/l and/or cholesterol greater than 7.8 mmol/l). The follow-up time was 67.4 +/- 27 months. It was hypothesised that reduction of elevated levels of triglycerides and/or cholesterol influenced favourably the incidence of angina pectoris, MI, stroke and total mortality. For ethical reasons, it was not possible to carry out the investigations with a control group. Therefore, we performed an internal comparison of 3 categories of lipid correction achieved during the trial (effective, moderate, insufficient). A substantial improvement of the lipid disorder was obtained by individualizing the therapy. Triglycerides and cholesterol decreased on average by 50% and 20%, respectively. The incidence of MI was 10 times higher than in the general population. With respect to the type of HLP, hypertriglyceridemia revealed a significantly higher incidence of MI compared with hypercholesterolemia and mixed HLP. The therapy variant was only of importance with respect to gallstone diseases accumulating in the CPIB-treated subgroups. We found a majority of cases with newly manifested angina pectoris and stroke in the group with moderate correction of both triglycerides and cholesterol. Patients with effective triglyceride and cholesterol correction suffered less frequently from MI than those with insufficient correction. This was also the case with secondary prevention in cases with MI prior to entry. There was no significant difference in the distribution of lipid categories at entry between those with and without recurrent infarction. In the group without reinfarction, however, the percentage with insufficient control diminished significantly. Associated risk factors such as hypertension, diabetes, smoking and obesity were of minor or no significance. In subjects with effective triglyceride correction, the total mortality was 0.97/1000 treatment months vs. 3.63 in insufficiently treated patients. The figures for MI mortality were 0.36 and 1.91, respectively.

[Relation between serum lipoprotein metabolism and biliary lipid metabolism]

This review concern with recent results regarding interrelationships between serum lipoprotein and bile acid metabolism. First, changes in bile acid metabolism in primary hyperlipoproteinaemia type II and type IV are described. In addition, influences of lipid-lowering drugs such as sitosterol, cholestyramine/colestipol, neomycin, nicotinic acid, clofibrate and thyroxin on serum lipoproteins and biliary lipid metabolism are discussed. Changes in lipoprotein metabolism in disorders of bile acid metabolism and effects of primary and secundary bile acids on lipoprotein metabolism, hepatic cholesterol metabolism and intestinal cholesterol absorption are described. In the final discussion interrelationships between very low density lipoprotein - triglycerides and cholic acid metabolism as well as low density lipoprotein and chenodeoxycholic acid metabolism are stressed. The positive correlation between serum triglycerides and lithogenicity of bile is underlined and the possible significance of high density lipoprotein-cholesterol as precursor of biliary cholesterol is discussed.

Bile acid content of gallbladder bile and stones in type IIb and IV hyperlipoproteinemia

We examined the bile acid composition of gallbladder bile using reversed-phase high performance liquid chromatography (HPLC), in normolipemic and hyperlipidemic (types IIb and IV) patients with cholelithiasis and compared them with normal subjects. Similarly, bile acid composition was determined n the gallstones of these patients. No free bile acids were found in any of the samples examined. We observed that gallbladder bile and gallstones of patients with type IV hyperlipidemia showed a significant increase in the percentage of glyco-conjugated bile acids and reduction in taurine conjugates. Based on this finding we postulate that in addition to biliary lipid composition bile acid composition may also play a role in the pathogenesis of cholesterol gallstone formation.

Increased production of triglyceride-rich lipoproteins after partial biliary diversion in the rhesus monkey

An interrelationship between bile acid and triglyceride metabolism is suggested by observations in patients with endogenous hypertriglyceridemia and in subjects treated with bile acid-binding resins or chenodeoxycholic acid. We investigated this possible interrelationship in the rhesus monkey. The effect of 14 days of partial bile diversion on plasma concentration and secretion rates of triglyceride-rich lipoproteins was studied by means of a stream-splitting device that permitted controlled interruption of the enterohepatic circulation. Diversion of 25% of the enterohepatic circulation resulted in increased bile acid synthesis and decreased bile acid secretion and pool size, and was associated with a 75% increase in fasting serum triglyceride concentration and a twofold increase in the rate of secretion of triglyceride-rich lipoproteins into plasma. Intraduodenal replacemtn of cholic acid during the period of bile diversion completely prevented the increase in lipoprotein secretion and partially prevented the increase in fasting plasma triglycerides, suggesting that these changes resulted from loss of bile acid rather than other components of bile. These studies show that partial removal of bile acids from the enterohepatic circulation augments the secretion of triglyceride-rich lipoprotein into plasma in the rhesus monkey. Elucidation of the mechanism of this effect may provide important new information concerning the control of hepatic lipoprotein secretion.

Prevalence of hyperlipoproteinemia in men with gallstone disease

Lipoprotein disorders are associated with changes in the bile lipid composition, and gallstone disease has been reported to be common in hyperlipoproteinemic patients. To find out whether there is a significant correlation between hyperlipoproteinemia and gallstone disease, we compared the prealence of hyperlipoproteinemia in a consecutive series of male gallstone patients with that in an age-matched consecutive series of gallstone-free patients. The gallstone patients were hyperlipoproteinemic in 43.5% as compared with 22.5% in the control patients. This difference was statistically significant. Prebetahyperlipoproteinemia (type IV) was the most common lipoprotein disorder in gallstone patients as well as in control patients.

Bile acid kinetics in relation to sex, serum lipids, body weights, and gallbladder disease in patients with various types of hyperlipoproteinemia;

Bile acid kinetics were determined in 15 normolipidemic and 61 hyperlipidemic subjects with the aid of [(14)C]cholic acid and [(3)H]chenodeoxycholic acid. The diet was standardized and of natural type. The total bile acid formation was within normal limits in patients with hyperlipoproteinemia types IIa and IIb. On the average the production of cholic acid (C) represented less than 50% of the total bile acid synthesis in both groups. The corresponding value recorded for the controls was 64+/-2% (mean+/-SEM). The synthesis of C in hyperlipoproteinemia type IIa was significantly below normal. Of the 27 patients with the type IV pattern, 18 had a synthesis of C and C + chenodeoxycholic acid (CD) that exceeded the upper range recorded for the controls. In these subjects the C formation represented 73+/-3% of the total bile acid synthesis. Similar findings were also encountered in the five patients with the type V lipoprotein pattern studied. The bile acid pool size of the 11 patients with hyperlipoproteinemia type IV, who had been cholecystectomized or suffered from cholelithiasis, was 900 mg smaller on the average than that of the other subjects with the same type of hyperlipoproteinemia. However, the pool size in the former subjects still tended to be higher than that of the control subjects without evidence of gallbladder "disease". In all groups of subjects the formation of bile acids tended to be higher in the male than in the female subjects. Bile acid synthesis showed no linear correlation to actual body weight, relative body weight, or body surface area. A moderate weight reduction in five patients (one with type IIb and four with type IV pattern) was followed by a 50% reduction of the C and CD synthesis.