Gasous hole closing in a polymer Langmuir monolayer.

The hole-closing phenomenon is studied in a polymer Langmuir film with coexisting gaseous and liquid phases both as a test of hydrodynamic theories of a two-dimensional fluid embedded in a three-dimensional one and as a means to accurately determine line tension, an important parameter determining size, shape, and dynamics within these and other membrane model systems. The hole-closing curve consists of both a universal linear regime and a history-dependent nonlinear one. Improved experimental technique allows us to explore the origin of the nonlinear regime.

Triglyceride synthesis in epididymal adipose tissue: contribution of glucose and non-glucose carbon sources.

The obesity epidemic has generated interest in determining the contribution of various pathways to triglyceride synthesis, including an elucidation of the origin of triglyceride fatty acids and triglyceride glycerol. We hypothesized that a dietary intervention would demonstrate the importance of using glucose versus non-glucose carbon sources to synthesize triglycerides in white adipose tissue. C57BL/6J mice were fed either a low fat, high carbohydrate (HC) diet or a high fat, carbohydrate-free (CF) diet and maintained on 2H2O (to determine total triglyceride dynamics) or infused with [6,6-(2)H]glucose (to quantify the contribution of glucose to triglyceride glycerol).

Chronic ethanol and triglyceride turnover in white adipose tissue in rats: inhibition of the anti-lipolytic action of insulin after chronic ethanol contributes to increased triglyceride degradation.

Chronic ethanol consumption disrupts whole-body lipid metabolism. Here we tested the hypothesis that regulation of triglyceride homeostasis in adipose tissue is vulnerable to long-term ethanol exposure. After chronic ethanol feeding, total body fat content as well as the quantity of epididymal adipose tissue of male Wistar rats was decreased compared with pair-fed controls.

Determination of interphase line tension in Langmuir films.

A Langmuir film is a molecularly thin film on the surface of a fluid; we study the evolution of a Langmuir film with two coexisting fluid phases driven by an interphase line tension and damped by the viscous drag of the underlying subfluid. Experimentally, we study a 4{'} -8-alkyl[1, 1{'} -biphenyl]-4-carbonitrile (8CB) Langmuir film via digitally imaged Brewster angle microscopy in a four-roll mill setup which applies a transient strain and images the response. When a compact domain is stretched by the imposed strain, it first assumes a bola shape with two tear-drop shaped reservoirs connected by a thin tether which then slowly relaxes to a circular domain which minimizes the interfacial energy of the system.

Novel application of the "doubly labeled" water method: measuring CO2 production and the tissue-specific dynamics of lipid and protein in vivo.

The partitioning of whole body carbon flux between fat and lean compartments affects body composition. We hypothesized that it is possible to simultaneously determine whole body carbon (energy) balance and the dynamics of lipids and proteins in specific tissues in vivo. Growing C57BL/6J mice fed a high-fat low-carbohydrate diet were injected with a bolus of "doubly labeled" water (i.

Quantifying rates of protein synthesis in humans by use of 2H2O: application to patients with end-stage renal disease.

A method is introduced for quantitating protein synthetic rates in humans by use of (2)H(2)O. Its validity was tested in subjects with end-stage renal disease. Six clinically stable subjects, hemodialyzed three times weekly, ingested (2)H(2)O to a body water (2)H enrichment of approximately 0.

Influence of diet on the modeling of adipose tissue triglycerides during growth.

We have studied the accretion of lipids in growing mice. We measured the rates of synthesis and degradation of triglycerides in epididymal fat pads of mice maintained for 44 days on a low-fat, high-carbohydrate diet (I) or a high-fat, low-carbohydrate diet (II). 2H2O was added to the drinking water for 14 days.