RESUMEN
In this study, the inhibitory effect and mechanism of rifampicin on the activity of tyrosinase were investigated for developing a novel tyrosinase inhibitor. It was found to have a significant inhibition on the activity of tyrosinase (IC50=90±0.6µM). From the kinetics analysis, it was proved to be a reversible and noncompetitive type inhibitor of the enzyme with the KI value of 94±3.5µM. The results obtained from intrinsic fluorescence quenching indicated that rifampicin could interact with tyrosinase. In particular, the drastic decrease of fluorescence intensity was due to the formation of a rifampicin-enzyme complex in a static procedure which was mainly driven by hydrophobic forces and hydrogen bonding. Moreover, the ANS-binding fluorescence analysis suggested that rifampicin binding to tyrosinase changed the polarity of the hydrophobic regions. Molecular docking analysis further revealed that the hydrogen bonds were generated between rifampicin and amino residues Leu7, Ser52, and Glu107 in the B chain of the enzyme. And the hydrophobic forces produced through the interaction of rifampicin with B chain residues Pro9, Pro14, and Trp106. This work identified a novel tyrosinase inhibitor and potentially contributed to the usage of rifampicin as a potential hyperpigmentation drug.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Monofenol Monooxigenasa/antagonistas & inhibidores , Rifampin/farmacología , Agaricales/enzimología , Inhibidores Enzimáticos/metabolismo , Cinética , Simulación del Acoplamiento Molecular , Monofenol Monooxigenasa/química , Monofenol Monooxigenasa/metabolismo , Conformación Proteica , Rifampin/metabolismoRESUMEN
Effects of extraction temperature, extraction time and ratio of water to material as well as their interactions on the yield of total polysaccharide from Herba lophatheri were studied by response surface methodology (RSM). The optimal conditions for the extraction of polysaccharides were determined to be the ratio of liquid to solid of 39.01, extraction time of 2.11h and extraction temperature of 97.09°C. Under these optimal conditions, the yield of polysaccharides obtained was 5.73±0.10%, which was well matched with the value predicted by the model. In vitro antioxidant assays showed that the polysaccharides HLP possessed significant inhibitory effects on superoxide radical. It also exhibited strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities, hydroxyl radical scavenging activities and its reducing power, ferrous ions chelating effect was also strong. These results suggested that H. lophatheri polysaccharides could be a suitable natural antioxidant and may be the functional foods for humans.
Asunto(s)
Medicamentos Herbarios Chinos/química , Poaceae/química , Polisacáridos/química , Agua/química , Medicamentos Herbarios Chinos/aislamiento & purificación , Depuradores de Radicales Libres/química , Humanos , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Polisacáridos/aislamiento & purificación , Propiedades de SuperficieRESUMEN
BACKGROUND: The policy environment in China is rapidly changing. Strategic planning may enable hospitals to respond more effectively to changes in their external environment, little evidence exists on the extent to which public hospitals in China adopt different strategies and the relationship between strategic decision-making and hospital performance. PURPOSES: The purposes of our study were to determine the extent to which different hospitals adopt different strategies, whether strategies are associated with organizational culture and whether hospital strategies are associated with hospital performance. METHODOLOGY: Presidents (or vice presidents), employees, and patients from 87 public hospitals were surveyed during 2009. Measures of strategic group were developed using cluster analysis based on the three dimensions of product position, competitive posture, and market position. Culture was measured using a tool developed by the investigators. Performance was measured based on profitability, patient satisfaction, and employee satisfaction with overall hospital development in the recent 5 years. The association of strategic group and organizational culture with hospital performance was analyzed using multivariate models. FINDINGS: Chinese public general hospitals were classified into five strategic groups that had significant differences in product positioning, competitive posture, and market position. Hospitals of similar types based on regulation adopted different strategies. Organizational culture was not strongly associated with hospital strategic group. Although strategic group was associated with hospital profitability and patient satisfaction in the models with or without control for hospital location, these effects did not persist after controlling for organizational culture, hospital level, and hospital location. PRACTICE IMPLICATIONS: It is important for public hospitals in China to make effective strategic planning and align their organizational culture with the strategies for better execution and therefore better performance. Moreover, the method of hospital strategic grouping in the study provides a new way to analyze management issues within a strategic group and between strategic groups.
Asunto(s)
Eficiencia Organizacional , Procesos de Grupo , Hospitales/normas , Cultura Organizacional , China , HumanosRESUMEN
OBJECTIVE: To measure perceptions of organizational culture among employees of public hospitals in China and to determine whether perceptions are associated with hospital performance. DATA SOURCES: Hospital, employee, and patient surveys from 87 Chinese public hospitals conducted during 2009. STUDY DESIGN: Developed and administered a tool to assess organizational culture in Chinese public hospitals. Used factor analysis to create measures of organizational culture. Analyzed the relationships between employee type and perceptions of culture and between perceptions of culture and hospital performance using multivariate models. PRINCIPAL FINDINGS: Employees perceived the culture of Chinese public hospitals as stronger in internal rules and regulations, and weaker in empowerment. Hospitals in which employees perceived that the culture emphasized cost control were more profitable and had higher rates of outpatient visits and bed days per physician per day but also had lower levels of patient satisfaction. Hospitals with cultures perceived as customer-focused had longer length of stay but lower patient satisfaction. CONCLUSIONS: Managers in Chinese public hospitals should consider whether the culture of their organization will enable them to respond effectively to their changing environment.