Isolation and Characterization of a Cellular Protein-Lipid Complex from Ascites Fluid Caused by Various Neoplasms

High concentrations of lipids in ascites fluid caused by peritoneal carcinomatosis have been described recently. Since their nature has not yet been clarified, we isolated ascitic lipids from 25 patients with various neoplasms for further characterization. After chromatography on Sephadex G-100 gels, the ascitic lipids were fractionated on a Biogel A-5m column in three peaks. The second and third peaks were identified as low and high density lipoproteins, which were most likely of plasmatic origin, and represented the major amounts of ascitic lipids. The first peak was eluted in the void volume, indicating a molecular weight over 5 million. It consisted, on the average, of 65.3% protein, 16.2% triglycerides, 7.4% phospholipids, and 7.0% cholesterol. In a CsCl gradient, this protein-lipid complex floated in the density range from 1.128 to 1.181 g/ml. Sodium dodecyl sulfate: polyacrylamide gel electrophoresis separated up to 11 protein subunits (Mr 29,000 to 97,000), and electron microscopy revealed globular particles of 36 to 64 nm in diameter. The macromolecular complex showed no immunological reaction against anti-{alpha}- and anti-ß-lipoproteins, but a single precipitation line against anti-liver-specific lipoprotein was seen. The biochemical characteristics of this protein-lipid complex proved to have a close relationship to liver-specific lipoprotein. It is most likely derived from cell membranes of the peritoneum detached by carcinomatosis

Association between cholesterol-phospholipid vesicles and cholesterol crystals in human gallbladder bile

Rapid aggregation of cholesterol-phospholipid vesicles in gallbladder bile seems to be the first event in the production of cholesterol crystals, a prerequisite for cholesterol gallstone formation. We examined the amount of these vesicles in 33 human gallbladder biles in relation to biliary lipid composition and to the presence of cholesterol crystals. Biliary microscopy detected cholesterol crystals in all 19 biles from patients with cholesterol gallstones but in none of 14 biles from patients with pigment stones. Gel chromatography was used to separate vesicles and micelles in the native bile with an eluting buffer containing 10 mM sodium cholate to prevent disruption of micellar lipids. Cholesterol, phospholipid and bile salt concentrations were measured in every fraction collected. Bile acid, phospholipid, cholesterol and total lipid concentrations were not significantly different in samples with and without cholesterol crystals. The cholesterol saturation index (1.4 ± 0.11 vs. 1.0 ± 0.08) was significantly (p < 0.01) higher in biles with crystals than without crystals. Gel filtration revealed a vesicular peak in addition to micellar fraction in 18 (23.1 ± 3.2% of total cholesterol) of the 19 biles with crystals but only in three (15.7 ± 2.4% of total cholesterol) of 14 biles without crystals. There was no relation between biliary lipid concentration or the cholesterol saturation index and the percentage of vesicular cholesterol in biles with or without crystals. The close association of vesicles and crystals in human gallbladder bile supports the contention that vesicles are important in the initial nucleation of cholesterol monohydrate crystals

Correlation of total cholesterol and protein in urine in patients with the nephrotic syndrome

The excretion of protein and cholesterol in 24 h urine was measured in 42 patients with the nephrotic syndrome. The finding of a positive correlation (r=0.76,p<0.01) between urinary cholesterol and urinary protein would be compatible with an enhanced glomerular filtration of plasma lipoproteins as the cause of lipiduria in the nephrotic syndrome