[Study of interaction of umbelliferone with three aromatic amino acids by fluorescence spectroscopy].

The interaction between umbelliferone (UMB) with tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe) was studied by using fluorescence (FS) and ultraviolet (UV) spectroscopy. The results show that UMB can strongly quench the fluorescence of the three aromatic amino acids with the maximum quenching wavelengths at 347, 303 and 282 nm, respectively. Data analyses based on the Stern-Volmer curve and the UV spectroscopy show that static quenching occurred through the formation of the complexes of UMB with each aromatic amino acid in a molar ratio of 1 : 1. The binding constant K(c) of UMB with Trp, Tyr and Phe is 2.993 x 10(6), 7.858 x 10(4) and 1.186 x 10(3) L x mol(-1) (298.15 K) and 2.702 x 10(4), 1.063 x 10(5) and 8.352 x 10(3) L x mol(-1) (310.15 K), respectively. The thermodynamic parameters indicate that UMB has a strong interaction with the three aromatic amino acids. Hydrogen bond and Van der Waals force may play a major role in the reaction of UMB with Trp, whereas hydrophobic interaction should be responsible for the binding of UMB with Tyr and Phe. In addition, the dipole-dipole interaction may be another factor in the reactions between UMB and the three aromatic aminoacids.

[Monitoring and analysis of vertical profile of atmospheric HONO, NO2 in boundary layer of Beijing].

Based on the scanning differential optical absorption spectroscopy (DOAS) system, field measurement of vertical profiles of HONO and NO2 was performed continuously from Aug. 27, 2007 to Sep. 4, 2007 in Chaoyang District of Beijing, and their vertical profiles were analyzed. Based on the acquired data, the typical vertical variation characteristics of HONO, NO2 and the ratio HONO/NO2 were discussed, and the possible formation sources of HONO were studied. The results indicated that the decrease of HONO with height was faster than the decrease of NO2. The study found good correlation between NO2 and HONO, as well as between the ratio HONO/NO2 and vapor, respectively. Therefore, the authors' conclusion is that HONO was formed by heterogeneous conversion of NO2 on surfaces or near ground and then transported to higher altitudes.

Population pharmacokinetic modeling and clinical application of vancomycin in Chinese patients hospitalized in intensive care units.

Management of vancomycin administration for intensive care units (ICU) patients remains a challenge. The aim of this study was to describe a population pharmacokinetic model of vancomycin for optimizing the dose regimen for ICU patients. We prospectively enrolled 466 vancomycin-treated patients hospitalized in the ICU, collected trough or approach peak blood samples of vancomycin and recorded corresponding clinical information from July 2015 to December 2017 at Tai Zhou Hospital of Zhejiang Province. The pharmacokinetics of vancomycin was analyzed by nonlinear mixed effects modeling with Kinetica software. Internal and external validation was evaluated by the maximum likelihood method. Then, the individual dosing regimens of the 92 patients hospitalized in the ICU whose steady state trough concentrations exceeded the target range (10-20 µg/ml) were adjusted by the Bayes feedback method. The final population pharmacokinetic model show that clearance rate (CL) of vancomycin will be raised under the conditions of dopamine combined treatment, severe burn status (Burn-S) and increased total body weight (TBW), but reduced under the conditions of increased serum creatinine (Cr) and continuous renal replacement therapy status; Meanwhile, the apparent distribution volume (V) of vancomycin will be enhanced under the terms of increased TBW, however decreased under the terms of increased age and Cr. The population pharmacokinetic parameters (CL and V) according to the final model were 3.16 (95%CI 2.83, 3.40) L/h and 60.71 (95%CI 53.15, 67.46). The mean absolute prediction error for external validation by the final model was 12.61% (95CI 8.77%, 16.45%). Finally, the prediction accuracy of 90.21% of the patients' detected trough concentrations that were distributed in the target range of 10-20 µg/ml after dosing adjustment was found to be adequate. There is significant heterogeneity in the CL and V of vancomycin in ICU patients. The constructed model is sufficiently precise for the Bayesian dose prediction of vancomycin concentrations for the population of ICU Chinese patients.

[Monitoring and analysis of air pollutants using DOAS in winter of Beijing].

Based on the differential optical absorption spectroscopy (DOAS) technology, the measurement of air pollutants (SOz, NO2, HONO and HCHO) was performed continuously from Jan 19, 2007 to Feb 8, 2007 in Peking University campus. The typical diurnal variation characteristic of SO2 concentration, the main source and the meteorological factors that influence the pollutants were analyzed. The results indicated that the typical diurnal variation of SO2 concentration has the same shape as the letter "V" when wind speed was low, and in the afternoon the SO2 concentration was the lowest, while in other time it was high. Coal-burning made prominent contribution to the concentration of atmospheric various pollutants in the heating period of Beijing. Wind speed played a leading role and other meteorological factors also have some effect, which resulted from the influence of the meteorology on diffusion, transmission, elimination of air pollutants.

Short- and long-term outcomes of laparoscopic versus open surgery for rectal cancer: A systematic review and meta-analysis of randomized controlled trials.

OBJECTIVES: The present meta-analysis aimed to evaluate the short- and long-term outcomes of laparoscopic surgery (LS) versus open surgery (OS) for rectal cancer. METHODS: PubMed, Web of Science, and Cochrane Library, were searched for eligible randomized controlled trials (RCTs) published up to June 2017. Operation related index, postoperative complication, and long-term survival rate and disease-free survival rate were evaluated by meta-analytical techniques. RESULT: Nine RCTs enrolling 4126 patients were included in the present meta-analysis. Compared to OS, LS had similar positive circumferential resection margin (CRM) and number of lymph nodes extracted (LNE) as well as long term 5 years survival rate and disease-free survival rate, but of which the risk tendency was higher in LS group. The short-term outcomes of major and total postoperative complication were lower in LS group. CONCLUSIONS: LS for rectal cancer was as safe and effective as OS in terms of long-term outcomes, but with lower postoperative complication.

Glucocorticoid-induced leucine zipper may play an important role in icariin by suppressing osteogenesis inhibition induced by glucocorticoids in osteoblasts.

BACKGROUND AND PURPOSE: Icariin is a potent stimulator of osteogenic differentiation; however, the mechanism underlying its osteogenic effect remains unclear. The osteogenic effect of icariin is related to the upstream glucocorticoid-induced leucine zipper (GILZ) signaling pathway, and antagonism with dexamethasone-induced osteoblast inhibition was noted. METHODS: MC3T3-E1 cells were cultured in induced medium treated with icariin with or without dexamethasone. After short interfering RNA (siRNA) were used to silence GILZ expression, the degree of mineralization, proliferation, and GILZ expression as well as the levels of osteogenic (OPG, RANKL, ALP, OC and RUNX2) markers were tested. RESULTS: Dexamethasone inhibited, while icariin increased, osteogenic activity, as indicated by ALP activity and calcium nodules. Meanwhile, dexamethasone dose-dependently (10-6M-10-4M) increased GILZ and RANKL expression and reduced ALP, OPG and OC, but the pattern of mRNA expression was reversed when icariin was added. Furthermore, GILZ (dexamethasone-induced) inhibition caused by icariin or moderately silenced by GILZ siRNA abolished the osteogenesis inhibition effect of dexamethasone, as indicated by the changes in the GILZ, ALP, OPG and RANKL expression levels; ALP activity; and calcium nodule. CONCLUSIONS: These results indicate that the GILZ-mediated osteogenic signal pathway is involved in the osteogenic effect induced by icariin.

Enhanced sensing of ascorbic acid, dopamine and serotonin at solid carbon paste electrode with a nonionic polymer film.

A nonionic poly(2-amino-5-mercapto-thiadiazole) film was electrodeposited on a solid carbon paste electrode via a potential scanning procedure, and used for amperometric sensing of ascorbic acid (AA), dopamine (DA) and serotonin (ST). The highly electrocatalytic activity of the sensor to the three analytes was demonstrated from the sensitive and well separated voltammetric signals. The polymer film did not show significant accumulation effect on all the three species, reducing the fouling and deactivation of the electrode surface as well as the mutual interference among the analytes. The sensor achieved amperometric sensitivities of 1.92 nA (nmol L(-1))(-1)cm(-2) to AA in the linear range of 0.025-1.95 µmol L(-1), 3.76 nA (nmol L(-1))(-1)cm(-2) to DA and 7.00 nA (nmol L(-1))(-1)cm(-2) to ST both in the linear range of 0.02-1.56 µmol L(-1). The lowest detection limits were found to be 1.5, 0.7 and 0.4 nmol L(-1) for AA, DA and ST, respectively. This sensor was successfully employed for the successive determination of AA, DA and ST in pharmaceutical samples. The good antifouling property and reproducibility of the proposed sensor can be attributed to the nonionic polymer film without electrostatic attraction to the ionized species in the solutions.

[Observational study of atmospheric HONO in summer of Beijing].

The concentration of HONO, NO2, O3 and other atmospheric pollutants were observed continuously by using differential optical absorption spectroscopy (DOAS) from 2007-08-14 to 2007-08-24 in Beijing, China. Diurnal variation characteristics of HONO and NO2 were analyzed. The HONO levels originated from the nocturnal direct emission were discussed. And the correlation between the heterogeneous formation of HONO and its related factors (BC, RH, and so on) was studied. The results showed that HONO had two peaks at about 01:00 and 06:00, respectively, while two peaks of NO2 concentrations appeared at about 01:00 and 07:00. The highest HONO(em)/HONO ratio of 31.3% was observed at about 20:00 between 19:00 to 07:00, and the average ratio was 15%. Good correlation of HONO(corr)/NO2 ratio with BC and RH at night was obtained. The correlation suggested that heterogeneous NO2 to HONO conversion processes may occur on BC surfaces by reaction with absorption water, and the average nighttime conversion frequency from NO2 into HONO (HONO/NO2) was calculated about 0.8% x h(-1). At the same time, the results showed that heterogeneous formation of HONO was increased with RH and inhibited at RH > 80%, and the hypothesis was further supported by detailed analysis of selected case.