On the suppression of plasma nonesterified fatty acids by insulin during enhanced intravascular lipolysis in humans
ABSTRACT During the fasting state, insulin reduces nonesterified fatty acid (NEFA) appearance in the systemic circulation mostly by suppressing intracellular lipolysis in the adipose tissue. In the postprandial state, insulin may also control NEFA appearance through enhanced trapping into the adipose tissue of NEFA derived from intravascular triglyceride lipolysis. To determine the contribution of suppression of intracellular lipolysis in the modulation of plasma NEFA metabolism by insulin during enhanced intravascular triglyceride lipolysis, 10 healthy nonobese subjects underwent pancreatic clamps at fasting vs. high physiological insulin level with intravenous infusion of heparin plus Intralipid. Nicotinic acid was administered orally during the last 2 h of each 4-h clamp to inhibit intracellular lipolysis and assess insulin's effect on plasma NEFA metabolism independently of its effect on intracellular lipolysis. Stable isotope tracers of palmitate, acetate, and glycerol were used to assess plasma NEFA metabolism and total triglyceride lipolysis in each participant. The glycerol appearance rate was similar during fasting vs. high insulin level, but plasma NEFA levels were significantly lowered by insulin. Nicotinic acid significantly blunted the insulin-mediated suppression of plasma palmitate appearance and oxidation rates by approximately 60 and approximately 70%, respectively. In contrast, nicotinic acid did not affect the marked stimulation of palmitate clearance by insulin. Thus most of the insulin-mediated reduction of plasma NEFA appearance and oxidation can be explained by suppression of intracellular lipolysis during enhanced intravascular triglyceride lipolysis in healthy humans. Our results also suggest that insulin may affect plasma NEFA clearance independently of the suppression of intracellular lipolysis.
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ABSTRACT: An automated open resonator system designed and constructed for precision measurement of loss tangent and dielectric permittivity of low absorbing materials at 60 GHz is reported. The use of a high-Q hemispherical Fabry-Perot cavity together with highly stabilized synthesized phase-locked Gunn oscillator sources and the superheterodyne receiver enabled a loss tangent value as low as 10 μrad to be measured. The system is automated by means of a precision lock-in amplifier, a V-band Hewlett-Packard spectrum analyzer and a Hewlett-Packard Vectra computer system with analog-to-digital conversion accessories. The synthesizer allows the collection of data at very small steps over the complete Gaussian beam, and, together with a statistical fitting, the Q determination can be made very accuratelyIEEE Transactions on Microwave Theory and Techniques 01/1990; DOI:10.1109/MWSYM.1990.99777 · 2.94 Impact Factor
Conference Paper: Vertical benchmarks for CAD[Show abstract] [Hide abstract]
ABSTRACT: Vertical benchmarks are complex system designs represented at multiple levels of abstraction. More effective than component-based CAD benchmarks, vertical benchmarks enable quantitative comparison of CAD techniques within or across design flows. This work describes the notion of vertical benchmarks and presents our benchmark, which is based on a commercial DSP, by comparing two alternative design flowsDesign Automation Conference, 1999. Proceedings. 36th; 02/1999
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ABSTRACT: PURPOSE: The aim of this study was to determine the effect of hyperinsulinemia on myocardial and hepatic distribution and metabolism of 14(R,S)-[(18)F]fluoro-6-thia-heptadecanoic acid ([(18)F]FTHA). PROCEDURES: Mitochondrial retention and intracellular lipid incorporation of [(18)F]FTHA were compared to that of [(14)C]-2-bromopalmitate or [(14)C]palmitate during hyperinsulinemic clamp vs. saline infusion in male Wistar rats. RESULTS: Mitochondrial (18)F activity was increased in the heart (1.7 +/- 0.4 vs. 0.5 +/- 0.1% ID/g, P < 0.05), whereas it was reduced in the liver (1.1 +/- 0.3 vs. 1.8 +/- 0.4% ID/g, P < 0.05) during insulin vs. saline infusion, respectively. Mitochondrial [(14)C]-2-bromopalmitate activity was affected by insulin in a similar way in both tissues. The fractional esterification of [(18)F]FTHA into triglycerides was impaired compared to [(14)C]palmitate in both tissues, and [(18)F]FTHA was insensitive to the shift of esterification of fatty acids into complex lipids in response to insulin. CONCLUSIONS: [(18)F]FTHA is sensitive to insulin-induced modifications of free fatty acid oxidative metabolism in rats but is insensitive to changes in nonoxidative fatty acid metabolism.Molecular Imaging & Biology 05/2006; 8(4). DOI:10.1007/s11307-006-0042-7 · 2.87 Impact Factor