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The study of regional drought characteristics is vital for identifying drought patterns and offering scientifically informed guidance for drought warnings. This research focuses on the Sichuan Basin, where the Standardized Precipitation Evapotranspiration Index (SPEI) was calculated across various time scales using meteorological data from 1963 to 2022. Wavelet analysis was applied to examine the periodic fluctuations of the SPEI across different time scales. Drought events were identified using run-length theory and spatially visualized with ArcGIS 10.7 interpolation techniques to elucidate the temporal and spatial dynamics of drought occurrences. The findings are as follows: (1) Over nearly 60 years, the SPEI in the Sichuan Basin fluctuated between −1.5 and 1, with an insignificant annual downward trend but a significant downward trend in autumn (p < 0.05). (2) The SPEI displayed a primary cycle of 6 years in spring, autumn, and winter, while the summer cycle matched the annual SPEI cycle of 8 years. (3) Drought events were more frequent in the eastern part of the basin compared to the west. The area with high drought frequency shifted counterclockwise from east to north, northwest, west, and south with the changing seasons. (4) Drought duration was longer in the western and northern regions of the basin than in the east. Severe drought events were mainly concentrated in the Chengdu Plain and the Central Sichuan Hilly Region, although the drought intensity index was lowest in the Chengdu Plain and Chongqing in eastern Sichuan. The peak values of drought showed an insignificant decreasing trend, indicating a potential expansion in the extreme impacts of drought disasters in the study area. [ABSTRACT FROM AUTHOR]

The composition of amino acids forming the active site of a CYP enzyme is impactful in its substrate selectivity. For CYP2E1, the role of PHE residues in the formation of effective binding orientations for its aromatic substrates remains unclear. In this study, molecular docking and molecular dynamics analysis were performed to reflect the interactions between PHEs in the active site of human CYP2E1 and various aromatic compounds known as its substrates. The results indicated that the orientation of 1-methylpyrene (1-MP) in the active site was highly determined by the presence of PHEs, PHE478 contributing to the binding free energy most significantly. Moreover, by building a random forest model the relationship between each of 19 molecular descriptors of polychlorinated biphenyl (PCB) compounds (from molecular docking, quantum mechanics, and physicochemical properties) and their human CYP2E1-dependent mutagenicityas established mostly in our lab, was investigated. The presence of PHEs did not appear to significantly modify the electronic or structural feature of each bound ligand (PCB), instead, the flexibility of the conformation of PHEs contributed substantially to the effective binding energy and orientation. It is supposed that PHE residues adjust their own conformation to permit a suitablly shaped cavity for holding the ligand and forming its orientation as favorable for a biochemical reaction. This study has provided some insights into the role of PHEs in guiding the interactive adaptation of the active site of human CYP2E1 for the binding and metabolism of aromatic substrates. [ABSTRACT FROM AUTHOR]

As a representative acidifier, lactic acid (LA) is widely used in the diets of aquatic animals. LA is the main supporter of energy metabolism and may be associated with drug metabolism. This study was designed to explore the pharmacokinetics of enrofloxacin (ENR) in Eriocheir sinensis (Chinese mitten crab) fed diets containing 0.1%, 0.2% and 0.3% LA (designated groups LA1, LA2 and LA3 respectively). The concentrations of ENR in the haemolymph, hepatopancreas and muscle were determined by HPLC after a single oral dose of 10 mg/kg. Our results showed that LA had a significant effect on the peak ENR concentrations in all the tissues (p < 0.05) by one‐way ANOVA analysis. There was a trend that Cmax (peak concentration) of ENR was elevated with LA levels increasing up to 0.3% in haemolymph, hepatopancreas, muscle and Tmax (time‐point of the peak concentration of the drug), t1/2β (elimination half‐life) and AUC(0‐∞) of ENR were shortened. Taken together, 0.3% LA might be effective in improving ENR pharmacokinetics in E. sinensis. Furthermore, it can be speculated that the enhanced biotransformation of ENR in the hepatopancreas mediated by LA is responsible for the differences in the pharmacokinetics of ENR in E. sinensis. [ABSTRACT FROM AUTHOR]