We have investigated the effects of methanol, acetonitrile, dimethyl sulphoxide or dioxane on enzyme kinetic parameters (Km and Vmax) p-nitrophenol hydroxylation, phenacetin deethylation metoprolol metabolism in rat liver microsomes, at different solvent concentrations. In case methanol (0.1 %-0.75 % v/v) (0.01 %-0.075 showed 1.3 2.5-fold increase respectively, Km with a less marked effect Vmax...

Short chain fatty acids (SCFAs) are potentially valuable as a topical therapy for distal ulcerative colitis. The mechanism of action is unknown but may involve improved intracellular energy production as previous evidence indicates that colonocyte oxidation of butyrate is impaired in ulcerative colitis. No information is, however, available on human mucosal metabolism of acetate and propionate ...

The kinetics and regulation of D-xylose uptake were investigated in the efficient pentose fermentor Candida succiphila, and in Kluyveromyces marxianus, which assimilate but do not ferment pentose sugars. Active high affinity (Km approximately 3.8 mM; Vmax approximately 15 nmol/[mg min]) and putative facilitated diffusion low-affinity (Km approximately 140 mM; Vmax approximately 130 nmol/[mg min...

The pattern of L-alanine uptake in isolated cells of interscapular brown adipose tissue has been determined. The uptake can be divided into the diffusion component (Kd = 0.55 min-1) and a saturable Na(+)-dependent transport (KM = 0.87 mM and Vmax = 155 nmol/min/10(6) cells). The saturable component can be subdivided into MeAIB-sensitive (KM = 1.63 mM and Vmax = 162 nmol/min/10(6) cells) and MeA...

The study determined the population estimates for Km and Vmax of phenytoin in Thai patients. The serum phenytoin concentrations collected prospectively from outpatients who received phenytoin were analyzed to estimate population pharmacokinetic parameters. There were 197 steady-state concentrations and associated dosage rates (mg/day) from 167 outpatients. The data were analyzed using NONMEM, a...

Maximal velocity (Vmax) is a well established biomarker for the assessment of tissue redox status. There is scarce evidence, though, that it does not probably reflect sufficiently in vivo tissue redox profile. Instead, the Michaelis constant (Km) could more adequately image tissue oxidative stress and, thus, be a more physiologically relevant redox biomarker. Therefore, the aim of the present s...

With black soil (Pachic Udic Argiboroll) of Northeastern China as the test object, an incubation test was conducted to investigate the effects of urease inhibitors, hydroquinone (HQ), phenyl phosphorodiamidate (PPD) and N-(n-Butyl) thiophosphoric triamide (NBPT), on the kinetic characteristics of soil urease under normal moisture and waterlogged conditions, aimed to study the changes of catalyt...