High-flux dialysis lowers plasma leptin concentration in chronic dialysis patients.

Leptin is a protein produced by fat cells and involved in body weight regulation. Plasma leptin is significantly higher in some hemodialysis (HD) patients than in normal controls. We examined the influence of dialyzer membrane biocompatibility and flux on elevated plasma leptin concentrations in hemodialysis patients.

Increased plasma leptin concentration in end-stage renal disease.

Leptin is a 16-kDa protein recently identified as the obese gene product involved in body weight regulation. Administration of recombinant leptin to ob/ob mice, which have a genetic defect in leptin production, reduces food intake and increases energy expenditure. Leptin is synthesized by fat cells, and in normal humans, plasma concentrations are proportional to adiposity.

Calorimetric analysis of lambda cI repressor binding to DNA operator sites.

Enthalpies and heat capacities were determined by isothermal titration calorimetry for bacteriophage lambda cI repressor binding to DNA containing various combinations of the three operator sites OR1, OR2, and OR3 (each comprising a consensus half-site and a specific nonconsensus half-site). Differential scanning calorimetry was employed to evaluate the effects of specific DNA binding on thermal melting of the N-terminal and C-terminal repressor domains. Principal findings of this study are as follows: (1) Binding of repressor to each of the DNA operators is dominated by a large negative enthalpy, in agreement with earlier van't Hoff analyses of quantitative footprint titration data [Koblan & Ackers (1992) Biochemistry 31, 57-65].

Differential scanning calorimetric study of 5-enolpyruvoyl shikimate-3-phosphate synthase and its complexes with shikimate-3-phosphate and glyphosate: irreversible thermal transitions.

The thermal denaturation of native Escherichia coli 5-enolpyruvoyl shikimate-3-phosphate (EPSP) synthase, its binary complex with shikimate-3-phosphate (S3P) and its ternary complex with S3P and glyphosate have been studied using highly-sensitive differential scanning calorimetry (DSC). All observed transitions are strongly scanning-rate-dependent and irreversible. Consistent with these observations, the data were better fit by a simple irreversible model than by the controversial reversible model more commonly employed.