Showing papers by "Scott M. Grundy published in 1976"

Chylomicron clearance in normal and hyperlipidemic man.

Abstract: A method has been developed for measurement of fractional clearance rates of chylomicrons in man The technique employs constant infusion of emulsified fat into the duodenum at a rate of 200 mg/kg/hr After 5 hr of infusion, concentrations of triglycerides (TG) in the chylomicron fraction become constant for the subsequent 5 hr Since the input of chylomicron-TG is known, fractional removal rates can be calculated from steady-state plasma levels In 21 patients with normal TG levels, clearance rates for chylomicrons were extremely rapid (t 1/2 for chylomicron-TG=45±29 (SD) min) In 30 patiemia, clearance was generally prolonged (t 1/2 =23±55 min) This delay in chylomicron clearance could have been due either to a defect in removal of all TG-rich lipoproteins or to competition for removal between endogenous and exogenous particles; a generalized defect in clearance capacity for plasma TG was apparently ruled out for most patients by the further observation that reduction endogenous TG by caloric restriction caused chylomicron removal to return to normal These studies also showed that endogenous-TG is removed much less efficiently than chylomicron-TG, and in some patients, this discrepancy is particularly marked

Changes in plasma triglyceride metabolism during withdrawal of bile.

Abstract: The relationship between bile acid turnover and plasma triglyceride metabolism was examined in a group of seven moderately overweight and hypertriglyceridemic men. Bile acid synthesis was stimulated by the continuous aspiration of duodenal contents so that 150% of the bile acid pool was removed in 18 hr. In comparison with the average concentration of very low density lipoprotein triglyceride (VLDL-TG) during a preceding 8–10 hr control period, bile withdrawal led to an increase in VLDL-TG of 34%, 43%, 32%, 14%, 26%, 14%, and 8% (mean +24%) in the seven men. In control studies performed on another day the mean change over a similar period of time, but without bile withdrawal, was +1% ( p The kinetics of VLDL triglyceride were studied in some of the subjects by analyzing the triglyceride specific radioactivity curves following injections of radiolabelled glycerol. In control studies of 26 hr duration the curves were resolved into two apparent exponential functions, the second part of the curve appearing between 15 and 18 hr after pulse-labeling. During bile withdrawal, the second apparent exponential developed sooner, within 4 hr of beginning the aspiration and coincided with the rise in triglyceride concentration. The fractional rate of the second exponential was at least as fast during bile withdrawal as during the control period despite the increase in VLDL-TG pool size, suggesting that the turnover of triglyceride was higher at a time when bile acid production was being stimulated.