The characteristics of cyclosporin A transport have been studied in cultured kidney epithelial cell line LLC-PK1. The uptake of cyclosporin A by LLC-PK1 cells was time-dependent and reached a steady state at about 30 min. The initial uptake was saturable and was inhibited by cyclosporin A analogs, cyclosporin C and D and by verapamil, but not by metabolic inhibitors such as 2,4-dinitrophenol an...

The use of accelerated temperature stability studies using the Arrhenius relationship is routine for estimating the stability of a drug at room temperature. Therefore, the acceleration method is used to determine the expiration date of dexamethasone aqueous formulation manufactured in Iran. A high-performance liquid chromatography (HPLC) method utilizing ultraviolet (UV) detection for dexa...

guaiacol peroxidases (gp) are haem-containing enzymes participating in many physiological processes in plants. the expression pattern of these enzymes is organ-specific and developmentally regulated. methods: the presence of gp activity in extract samples, prepared from crocus sativus l. corms that were either dormant or rooting for 3, 6 and 10 days, was investigated. results: kinetic studies r...

The activities of acetylcholinesterase (ACHE) and butyrylcholinesterase (BuChE) in rat brain capillaries were measured as a function of temperature. Arrhenius plots of the data revealed that AChE exhibits a biphasic Arrhenius plot with a distinct break (transition temperature) at about 15.2 kcal/mol. In contrast, BuChE did not show evidence of discontinuity. BuChE showed an activation energy hi...

The effect of temperature on the activation energies of mitochondrial enzymes of the yeast Saccharomyces cerevisiae was examined. Non-linear Arrhenius plots with discontinuities in the temperature range 14-19 degrees C and 19-22 degrees C were observed for the respiratory enzymes and mitochondrial ATPase (adenosine triphosphatase) respectively. A straight-line Arrhenius plot was observed for th...

The Arrhenius plot of the de-excitation rate of tryptophan triplet state deviates from linearity in the physiological temperature range for several proteins with buried tryptophans, similarly to the behaviour of enzyme activity. A model is presented featuring two de-excitation pathways whose effectiveness is regulated by protein dynamics.

In a previous paper [Bag and Hu, Phys. Rev. E 73, 061107 (2006)], we studied the mean lifetime (MLT) for the escape of a Brownian particle through an unstable limit cycle driven by multiplicative colored Gaussian and additive Gaussian white noises and found resonant activation (RA) behavior. In the present paper we switch from Gaussian to non-Gaussian multiplicative colored noise. We find that ...

The rate of hydrolysis of trans -[Cr(NH ) F ] was obtained as a function of acid concentsation in perchloric, sulfuric and nitric acid at 3Q°C. The results have been analyzed by the treatment of Bunnett and Olsen. Values of the parameter ?in Olsen equation are consistent with the participation of water as a proton-wansfer agent in the rate-determining step. The Arrhenius plot for perchlori...