Many empirical parameters have been suggested to measure solvent effects in chemical reactions. Gutmann's donor number has been a successful parameter to quantify the electron-donating property of the solvent molecule; it is defined as the enthalpy change of the addition reaction of solvent molecule to SbCl(5) in 1,2-dichloroethane. Calorimetric measurements can be applied to determine the qu...

Recent experiments reported that proton mobility in tetramethylurea (TMU) solutions is much slower than in urea solutions of the same molarity, and this (as well as the significantly retarded water reorientation) was ascribed to hydrophopic effects. In order to further explore the mechanism of proton transport in these solutions, reactive molecular dynamics simulations using a multistate empiri...

Aqueous solvation of small amphiphilic molecules exhibits a unique and complex dynamics, that is only partially understood. A recent series of studies on the hydration of small organic compounds, such as tetramethylurea (TMU), trimethylamine N-oxide (TMAO) and urea, has provided strong evidence of a slowdown of the dynamics of the hydrating water molecules. However, the mechanism of this slowdo...

Castle, Paul C., Adam L. Macdonald, Andrew Philp, Anthony Webborn, Peter W. Watt, and Neil S. Maxwell. Precooling leg muscle improves intermittent sprint exercise performance in hot, humid conditions. J Appl Physiol 100: 1377–1384, 2006. First published December 8, 2005; doi:10.1152/japplphysiol.00822.2005.—We used three techniques of precooling to test the hypothesis that heat strain would be ...

To the Editor: A range of infectious diseases have been described in asymptomatic immigrants (1), which may justify the implementation of screening after obtaining consent. In particular, asymptomatic malaria caused by Plasmodium falciparum parasitemia among recently arrived immigrants may be a major public health problem outside malaria-endemic areas because these patients may be involved in a...

BACKGROUND Intravenous glucose infusion into ambulatory dogs results in attenuation of exercise-induced increase of both rectal and thigh muscle temperatures. HYPOTHESIS That glucose (Glu) infusion attenuates excessive increase in body temperature from restricted activity during confinement deconditioning. METHODS Rectal (Tre) and quadriceps femoris muscle (Tmu) temperatures, metabolic rate...

A rapid continuous-Ñow technique for the quantitative determination of hydrogen isotope ratios in organic materials and water, at natural abundance levels, is described. Samples are pyrolysed in a helium stream at 1080 ÄC over an inert form of carbon. Hydrogen is separated from the other pyrolysis gases by gas chromatography and enters the ion source of the isotope ratio mass spectrometer (IRMS...

The molecular basis of the ability of bacteria to live on caffeine via the C-8 oxidation pathway is unknown. The first step of this pathway, caffeine to trimethyluric acid (TMU), has been attributed to poorly characterized caffeine oxidases and a novel quinone-dependent caffeine dehydrogenase. Here, we report the detailed characterization of the second enzyme, a novel NADH-dependent trimethylur...