ABSTRACT
Harpagoside (HAR) is believed to be a main compound in Scrophularia ningpoensis which possess a broad of biological activities.Human serum albumin (HSA) has important physiological roles in transportation, distribution and metabolism of many endogenous and exogenous substances in body.It is great significance in pharmacology to investigate the interaction mechanism of HAR and HSA.In this work, the interaction between HAR and HSA was investigated by fluorescence and ultraviolet absorption spectroscopy at different pH (pH=4.0, 7.4, and 9.0) and temperatures (297, 310 and 323 K).The experimental results showed that the HAR could cause the fluorescence quenching of HSA through a static quenching procedure, showing that the HAR regularly quenched the intrinsic fluorescence of HSA, and a decrease in the quenching constant was observed with an increase in temperature.Under different conditions, all the magnitude of binding constants (KA) was larger than 105 L/mol and the number of binding sites (n) in the binary system were approximate to 1.Base on the magnitude of enthalpy and entropy changes, the negative values of ΔG, ΔH and ΔS revealed that the binding of HAR with HSA was spontaneous and exothermic process, and the main interaction forces of the HAR with HAR were van der Waals forces and/or hydrogen bonding interaction.The binding distance (r) between the HAR and HSA was calculated to be about 4.2 nm based on the theory of F(o)rster′s nonradiation energy transfer, which indicated that the energy transfer from HSA to HAR occurred with high possibility.What was more, the synchronous florescence spectroscopy confirmed the conformational changes of HSA during the binding reaction.
ABSTRACT
Objective To explore the diagnostic value of dilated intercellular space detected by light microscope for non-erosive reflux disease (NERD) and erosive esophagitis (RE). Methods A total of 104 subjects were divided into normal control group (n = 20), NERD group (n = 30) and RE group (n = 54).Biopsies were taken at 2-3 cm above the dentate line and were examined by light microscope to calculate the intercellular space and compared between different groups. Results The mean values of intercellular space in RE ( 1.40 ±0. 17 μm) and NERD ( 1.11 ± 0. 14 μm) were significantly higher than that in control group (0.66±0. 18 μm, x2 = 154. 170, P =0.000). But no significant difference was noted between RE and NERD groups ( t = 0. 044, P = 0. 834). The cut-off value of mean intercellular space with light microscope was 0. 89 μm, with sensitivity and specificity at 95.2% and 95.0%, respectively. Conclusion Dilated intercellular space under light microscope can be a sensitive, specific and objective indicator of NERD.