Postprandial chylomicron remnant clearance was studied in six patients with familial combined hyperlipidemia (FCH) and seven control subjects by using an oral retinyl palmitate (RP) fat-loading test. The chylomicron remnant clearance (Sf < 1,000 fraction), expressed as the area under the RP curve (AUC-RP), was delayed in FCH subjects (65.05 +/- 12.84 hours x [mg/L]) compared with control subjec...

A mother and her son who have lipoprotein phenotype I are described. They differed from subjects with lipoprotein lipase deficiency in that lipoprotein lipase was present in adipose tissue respectively at 30- and 2-fold the levels seen in normal subjects, and from subjects with apoprotein C-II deficiency in that apoprotein C-II was present in their plasma. They appeared to have an inhibitor to ...

The separation of rat epididymal adipocytes into plasma-membrane, mitochondrial, microsomal and cytosol fractions is described. The fractions, which were characterized by marker-enzyme analysis and electron-micrographic observation, from the cells of fed and 24 h-starved animals were used to prepare acetone/diethyl ether-dried powders for the measurement of lipoprotein lipase activities. The hi...

An assay has been developed for specific measurement of two different lipase activities in postheparin plasma. Lipoprotein lipase, derived from extrahepatic sources, is measured as protamine-inactivated lipase activity; hepatic lipase activity is protamine-resistant under the conditions of this assay. In 100 normal subjects, both enzyme activities were noted to be related to age and sex. Protam...

The role of insulin in the regulation of human adipose tissue lipoprotein lipase was evaluated. Adipose tissue heparin-releasable lipoprotein lipase (thought to be related to peripheral clearance of plasma triglycerides) was low in insulin-deficient, untreated hyperglycemic diabetic subjects (P less than 0.001) and treatment of hyperglycemia returned the activity to normal. In chronic hyperinsu...

Lipoprotein lipase is a key enzyme in the regulation of lipid fuel disposal,3 and it provides fatty acids for tissue utilization by catalyzing the hydrolysis of triacylglycerol circulating in triglyceride-rich lipoproteins. Anchored to the surface of the capillary endothelium by glycosaminoglycans, lipoprotein lipase hydrolyzes plasma chylomicrons and VLDL to remnant particles. As such, lipopro...

We compared two methods for the direct selective measurement of hepatic lipase and lipoprotein lipase activities in human plasma after intravenous administration of heparin. Except for the emulsifier (gum arabic vs lecithin), the two assay media for hepatic lipase are essentially similar. Results for hepatic lipase by these two assays correlate well (r = 0.99). The assays for lipoprotein lipase...

Hormone-sensitive lipase and cholesterol ester hydrolase of chicken adipose tissue were markedly activated by adenosine 3’:5’-monophosphate (CAMP)-dependent protein kinase (on the average, 235 to 275%); occasionally as much as 1000%). Diglyceride and monoglyceride hydrolases were also activated, but to a lesser extent (60 to 87%). The activation of all four hydrolases was inhibited by protein k...

Lipoprotein lipase released from the rat heart during a 30-s perfusion with heparin was compared to the lipase remaining in the heart tissue. The perfusate, containing the heparin-releasable enzyme, as well as the heart tissue extract ("residue"), was purified on heparin-Sepharose affinity columns. Both purified fractions showed pronounced inhibition by 1 M NaCl and by antiserum to heart lipopr...