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A second polymorphic trait of rabbit serum high density lipoprotein (HDL) has been revealed by a new antiserum. The antigen detected by this antiserum appears to be inherited as an autosomal dominant trait. No obvious association was found between the new polymorphic trait (provisionally referred to as the R 67 antigen) and the already established MDL antigen, Hl 1. [ABSTRACT FROM AUTHOR]

Presents the serum lipid patterns found in patients with cerebral thrombosis. Difference in serum cholesterol concentrations; Alpha-lipoprotein cholesterol in both male and female patients; Association between atherosclerosis and lipid metabolism.

During its prolonged period of gestation, the fetal guinea pig gradually develops a striking hyperlipemia (plasma triglycerides ca. 500–1500 mg/dl) and fatty liver (hepatic triglycerides ca. 25% of wet weight). The parenchymal cells of the liver contain not only many fat droplets in the cytoplasm, but also large numbers of osmiophilic particles, interpreted as precursors of plasma lipoproteins, within profiles of the cisternae and secretory vesicles of the Golgi apparatus. Similar particles are found in intercellular spaces, in the space of Disse, and in the hepatic sinusoids. Near the end of gestation, these particles enlarge to the size range characteristic of chylomicrons secreted from the intestinal mucosa after ingestion of fat. At the same time, the hyperlipemia increases and is characterized by the accumulation of particles resembling chylomicrons morphologically and chemically. The results are interpreted as evidence of intense hepatic synthesis and secretion of very low density lipoproteins which may be related to the extensive transplacental transport of free fatty acids known to occur in this species. After birth, the hyperlipemia subsides rapidly and the hepatic steatosis more gradually. The blood plasma of the guinea pig fetus also contains moderate amounts of low density and high density lipoproteins. The latter decrease to barely detectable levels during the first 2 wk of postnatal life. Comparably low levels of high density lipoproteins are found in nonpregnant and pregnant adults.

Ponies fasted for up to 8 days showed, both by agarose electrophoresis and preparative ultracentrifugation, the appearance of a pre-β-migrating, very low density lipoprotein fraction in plasma. This lipoprotein differs from the very low density lipoprotein found in humans and rats in that it contains a relatively smaller amount of total cholesterol, 85% of which is present in the unesterified form. By the 8th day of fasting, plasma triglyceride concentrations had increased from a prefasting level of 20 mg/dl to as high as 1000 mg/dl. The increase in plasma lipid concentrations as a result of fasting was highly variable. Accumulation of plasma cholesterol and triglyceride after injection of Triton WR 1339 was not related to the degree of fasting hyperlipidemia. This suggests that the hyperlipoproteinemia of fasting may result from an impaired utilization of very low density lipoproteins.

A modification of the Pratt and Dangerfield technique of acrylamide gel concentration gradient electrophoresis has been used to study low density lipoproteins from fasting human beings. Prestained plasma from normal subjects and from patients with Fredrickson's type II hyperbetalipoproteinemia was electrophoresed in continuous gradient gel columns (approximately 3.5–8%). Reproducible low density lipoprotein patterns were obtained, and two major bands of low density lipoproteins as well as trace amounts of two to five other low density lipoproteins were seen in normal plasma. Plasmas from patients with hyperbetalipoproteinemia were more heterogeneous. Abnormal plasmas showed as many as six major low density lipoprotein bands and six minor bands. Patterns were constant for an individual but varied between patients. The major bands frequently had obviously different mobilities from those in normal plasma. Extensive experiments, using a large number and variety of mixed plasmas (normal, type II, and others) or plasmas run separately in divided gel columns, led to a numbering system of the low density lipoproteins comprised of 15 discrete bands. In addition to the changes seen in the low density lipoproteins in patients with hyperbetalipoproteinemia,reduced amounts of high density lipoproteins were consistently found.