Paul H. Schreibman

Cholesterol Metabolism in Human Obesity

An experiment was undertaken to test whether in severe obesity cholesterol production rates obtained by isotope kinetic analysis (two-pool compartmental analysis) are comparable to those measured by chemical sterol balance techniques. Eight severely obese but normocholesterolemic patients were studied by the balance method, and five of these eight were studied by compartmental analysis. Cholesterol turnover was 10% higher by compartmental analysis. In the entire group of eight patients cholesterol turnover was greater than twice that found previously in nonobese patients studied under similar conditions with bile acids and neutral sterols both participating in the increase. This increment was directly related to excess body fat and to adipose cellularity, with correlation co-efficients of 0.66 and 0.72, respectively. The amount of cholesterol in the slowly turning over pool B was related to degree of adiposity, but that in plasma and in pool A did not differ from values in nonobese patients.

HYPERLIPIDEMIA IN AN ADULT DIABETIC POPULATION.

Of 98 adult-onset diabetic patients selected at random from an ambulatory clinic, 37.8 per cent were found to have hyperlipidemia. In follow-up examination of the hyperlipidemic patients, 23 per cent had hyper-β-lipoproteinemia (Type II), 58 per cent had hyper-pre-β-lipoproteinemia (Type IV), 13 per cent had increased plasma β-and pre-β-lipoproteins (combined type) and 6 per cent had reverted to normal values. Type IV patients, as a group, were distinguished by greater hyperglycemia and relative body weight. Chylomicronemia was not observed in this study group. Hyperlipoproteinemia was frequent in this adult-onset diabetic population and differed in several respects from similar data in untreated juvenile-onset diabetes reported by others.

Familial type IV hyperlipoproteinemia.

Abstract A 17-year-old girl with asymptomatic hyperlipemia was found to have a Type IV hyperpre-beta-lipoproteinemia. The diagnosis was established by measurement of fasting triglycerides and plasm...

Metastatic Insulinoma Treated with Streptozotocin

Abstract A patient with hepatic metastases of an insulin-producing islet cell carcinoma has been successfully treated with streptozotocin. At 6 months posttreatment, liver scans demonstrate complet...

Post-Heparin Lipolytic Activity in Diabetic Patients with a History of Mixed Hyperlipemia: Relative Rates Against Artificial Substrates and Human Chylomicrons

The mechanism responsible for the accumulation of chylomicrons in mixed hyperlipoproteinemia (Type 5) is not known. Assays of the plasma-clearing factor, lipoprotein lipase, with artificially prepared substrates have been normal or only mildly depressed in this condition. The recent report of a patient in whom there was marked depression of activity against native chylomicrons despite normal activity against an artificial substrate suggested, however, that there might exist a qualitative defect in the function of lipoprotein lipase undisclosed by assays with the artificial substrate in general use. Accordingly, the lipolytic activity of post-heparin plasma from five diabetic patients with mixed hyperlipoproteinemia was measured against two artificial substrates and two preparations of human chylomicrons. There was good correlation between activity against coconut oil and each of the three other substrates over a wide range of plasma glyceride concentrations and post-heparin lipolytic activities. The data support the conclusion that plasma post-heparin lipolytic activity in diabetic patients with mixed hyperlipoproteinemia is qualitatively normal.

Decreased post-heparin lipases in Graves's disease.

Abstract The plasma post-heparin lipolytic activity (PHLA) and post-heparin monoglyceridase activity (PHMA) were determined in patients with Gravess disease and treated toxic nodular goiter. Both enzymes were markedly reduced in patients with active Gravess disease. Fasting serum triglycerides were normal or slightly below normal despite low post-heparin lipases. In these patients, restudied after propranolol therapy or within six months of euthyroid control with 131l, propylthiouracil or methimazole, PHLA and PHMA remained below normal. A separate group of patients with treated Gravess disease, who were euthyroid for as long as six years, also had low post-heparin lipases. Enzyme activity did not correlate with the presence of the long acting thyroid stimulator. In contrast, patients with treated toxic nodular goiter had normal PHLA and PHMA. Control subjects made hypermetabolic with tri-iodothyronine or thyroxine had normal post-heparin enzyme activities. Persistently low PHLA and PHMA may be a marke...

Effect of antilipolytic compounds on cyclic 3',5'-adenosine monophosphate activation of adipose tissue lipolysis.

The lipolytic effect of cyclic 3′, 5′-adenosine monophosphate (cAMP) is inhibited by the beta-adrenergic blocker propranolol. This is demonstrated on both isolated fat cells and intact epididymal fat pad preparations. A cell-free extract of either rat or human adipose tissue contains a lipase system which can be activated by cAMP. This activation is also prevented by propranolol as well as the alpha-adrenergic blocker, phentolamine, in a dose-related fashion. Because of this nonspecific action, pharmacologic differentiation of alpha- or beta-adrenergic receptor sites should be based upon direct measurements of cyclic nucleotide, adenyl cyclase or phosphodiesterase, and not target enzyme activity.

Post-Heparin Lipolytic and Monoglyceridase Activities in Fasted Man

Summary Prolonged fasting in man causes a significant decrease in post-heparin lipolytic and monoglyceridase activities. Activity is restored after refeeding. Plasma triglycerides declined in the face of diminished clearing factor lipase.