Opto-Chemical Micro-Capillary Clocks

Opto-chemical capillary clocks are presented that are based on the measurement of a colored segment in a microchannel (a capillary). Color is created by a chromogenic chemistry involving the oxidation of a (virtually colorless) leuco-dye. Poly(ethylene glycol) (PEG) is used as a solvent, and indigo and thioindigo (in their reduced leuco forms) act as oxygen-sensitive dyes. The clock is started by removing one seal at the end of the capillary. A visible color change occurs as air diffuses into the microchannel due to an irreversible color reaction. The length of the colored segment is proportional to the time elapsed. PEGs of different average molar mass affect the diffusion rate of oxygen in the microchannel and thereby affect the rate of the migration of the color front. Both temperature and relative humidity exert a strong effect. Six types of such clocks are described that enable times to be determined in the range from 1 day to 6 months, possibly of even decades

Effect of dietary restraint during and following pegylated recombinant leptin (PEG-OB) treatment of overweight men

Effect of dietary restraint during and following pegylated recombinant leptin (PEG-OB) treatment of overweight men. Lejeune MP, Hukshorn CJ, Saris WH, Westerterp-Plantenga MS. Department of Human Biology, Maastricht University, Maastricht, The Netherlands. [email protected] OBJECTIVE: To examine the effect of dietary restraint during and following pegylated recombinant leptin (PEG-OB protein) treatment in overweight men. DESIGN: A randomized double-blind placebo-controlled trial in 24 overweight men (BMI: 28.8+/-0.3 kg/m(2); age: 34.8+/-0.9 y). PEG-OB protein (80 mg) or placebo was administered subcutaneously weekly for 6 weeks, combined with a 2.1 MJ/day energy restriction program. Dietary restraint was determined by the Three-Factor Eating Questionnaire before and after treatment, and after 8 weeks follow-up. RESULTS: During treatment dietary restraint increased, and general hunger, resting energy expenditure and respiratory quotient decreased similarly in the PEG-OB and the placebo group. With PEG-OB treatment, additional weight loss (P<0.03) was observed. During 8 weeks follow-up, body weight increase was larger in the PEG-OB group compared to placebo (P<0.05), and body weight regain was faster. Body weight regain was inversely correlated with the increase in cognitive dietary restraint during treatment (PEG-OB group: r(2)=0.49, P<0.02; placebo group: r(2)=0.60, P=0.01). CONCLUSION: Although treatment with PEG-OB protein led to a greater body weight loss relative to placebo, weight maintenance thereafter was mainly supported by dietary restraint, which was more effective in the placebo-treated group, resulting in a slower regain of body weight