Olga Terebus-Kekish

SERUM LIPOPROTEINS AND HUMAN NEOPLASTIC DISEASE.

Abstract Serum lipoproteins have been measured m 20 normal subjects. Young women from a convent were studied weekly for a 12-week period, and women from the Institute staff in single experiments. The subjects were divided on the basis of family history for cancer. The same studies were done on 9 young women with advanced cancer of the breast. Lipoproteins with densities less than 1.006 g/ml, e.g., Sf20–100 and Sf0–20, and Sf10–20 class floating in solution density 1.0635 g/ml, are elevated in serum from subjects with advanced cancer of the breast. Of these, Sf0–20 (1.006, unaltered serum) was significantly higher in subjects with cancer. These elevations were not present in the normal subjects who had a negative family history for cancer. The high-density lipoprotein Sf0–4 (1.125, NaCl) which is the major component floating at solution density 1.125 g/ml, was very low in subjects with cancer. It was low consistently in only the normal subjects with cancer in their immediate blood relatives. These differences were highly significant. Although this high-density lipoprotein fluctuates during the menstrual cycle, and each serial subject had a stable range of values, it is possible that a pronounced family history for cancer may influence the serum levels of Sf0–4 or HDL2.

Disclosure and characterization of new high-density lipoproteins in human serum

Abstract Sequential removal, with solutions of increasing density, of the lower-density lipoproteins has made possible the unmasking of previously undescribed high-density (D = 1.0635−1.125 g/ml) lipoproteins. These new high-density lipoproteins were revealed as one or two discrete boundaries in the Spinco Model E ultracentrifuge. They are in the density range between HDL 1 and HDL 2 , and have been classified as S f 12–20 (1.125, NaCl) and S f 4–12 (1.125, NaCl), while the heavier boundary is termed S f 0–4 (1.125, NaCl). This heavier boundary has usually been named HDL 2 .

Properties of lipoprotein lipase extracted from livers of normal rats and livers and tumors of rats bearing Walker carcinosarcoma 256

Abstract Extracts of acetone powders made from normal rat livers, and livers and tumor tissues from male rats bearing the Walker carcinosarcoma 256 have been made. No heparin was given to the animals at any time. The properties of the lipases studied indicate that they are lipoprotein lipases, even though they will hydrolyze well a 1.5% coconut oil emulsion. There is some indication that these enzymes preferentially hydrolyze the lower-density lipoproteins i.e., S f 100–400 and then proceed to the S f 20–100 and 0–20 classes, in in vitro experiments. The enzyme from the liver tissue of rats bearing the Walker carcinoma 256 is especially active in reducing the quantity of all the low-density lipoproteins measured in these experiments. The enzyme from tumor tissue is quite dependent upon heparin. The enzymes from all the tissues examined have characteristics which are like the lipoprotein lipase extracted from normal rat heart, and it may be suggested that the tissue extracts tested in these experiments do have lipoprotein lipase, or clearing factor, activities.

Low-density lipoproteins and lipoprotein lipase activity in tissues from rats bearing Walker carcinosarcoma 256

Abstract It has been observed that the low-density lipoproteins, especially the triglyceride-carrying S f 20–400, are present in large quantities in sera of rats with the Walker carcinosarcoma 256. At the same time, although the lipoprotein lipase activity is maintained at high levels in the sera to the 21st day after implantation, the hyperlipemia remains. Large quantities of similar lower density lipoproteins were observed also in tumor tissue between the 14th and 21st day, suggestive of transport to and penetration of triglyceride hydrolysis products into the tumor tissue. By the 28th day, the S f 20–400 lipoproteins had accumulated greatly in the blood along with diminished lipoprotein lipase activity, while virtually no lipoproteins nor enzyme activity could be measured in the tumor tissue.

ADDITIONAL EVIDENCE FOR THE EXISTENCE OF "NEW" HIGH-DENSITY LIPOPROTEINS IN HUMAN SERUM.

Abstract Two recently described high-density lipoproteins are characterized further. The hydrated densities for these components floating in solution density 1.125 g/ml are: S f 20−12, 1.071 g/ml; S f 12−4, 1.079 g/ml. When they occur in human sera, S f 12−4 especially, is quite consistently present. They have not been observed in rat sera. Experimental measurements of densities during separation procedures are reported.