Asymmetric Construction of 4 H-Pyrano[3,2- b]indoles via Cinchonine-Catalyzed 1,4-Addition of 2-Ylideneoxindole with Malononitrile.

A highly enantioselective [4 + 2] annulation of 2-ylideneoxindole with malononitrile has been accomplished by cinchonine catalysis under mild conditions. The corresponding enantiomerically enriched 4 H-pyrano[3,2- b]indoles were generated in moderate to high yields (up to 94%) with excellent enantioselectivities (up to 98% ee). To explain the stereoselectivity of the organocatalytic Michael-ammonization cascade, we also carried out the control experiments and proposed plausible transition-state models for the catalytic cycle based on the observed stereochemistry of the products. In addition, some of the products showed moderate antibacterial activity against S. aureus and S. epidermidis in vitro, which might be considered as a potential clue for the discovery of new antimicrobial agents.

Quantitative Analysis of Health Risk Perception, Exposure Levels, and Willingness to Pay/Accept of PM2.5 during the 2014 Nanjing Youth Olympic Games.

Local governments in China regularly implement short-term emission control measures to improve air quality during important sporting events. As a condition for hosting the 2014 Youth Olympic Games (YOG), the Nanjing government agreed to temporarily and substantially improve air quality. Regression analysis, Spearman correlation analysis, χ2 test, and the contingent valuation method were used to explore the effects of robust, short-term air pollution control measures on risk perception, daily exposure to PM2.5, risk acceptance levels, and willingness to pay/accept (WTP/WTA) for reductions in air pollution for the benefit of reducing health risks. Postimplementation, the respondents' risk perception levels presented the following changes: during the YOG, the respondents perceived the lowest effects of haze pollution while after the YOG, they perceived the highest effects. The changes in risk acceptance levels showed the same tendency. Furthermore, after the YOG, the respondents asked for the most economic compensation, and their willingness to pay for risk reduction also reached the highest level. This study reveals the need to increase the public's understanding of the health risks of air pollution, protect those populations most exposed to high levels of PM2.5, and take more effective long-term measures to meet local residents' demands for improved air quality.

A comparison of individual exposure, perception, and acceptable levels of PM2.5 with air pollution policy objectives in China.

Atmospheric pollution has emerged as a major public health issue in China. Public perception and acceptable risk levels of air pollution can prompt individual behavioral changes and play a major role in the public's response to health risks. Therefore, to explore these responses and evaluate what constitutes publicly acceptable concentrations of fine particulate matter (PM2.5), questionnaire surveys were conducted in three representative cities of China: Beijing, Nanjing, and Guangzhou. Great differences in public risk perception were revealed. Public perception of the health effects of air pollution (Effect) and familiarity with it (Familiarity) were significantly higher in the winter than in the summer, and also during severe haze days compared with typical days. The public perception of trust in the government (Trust) was consistent across all conditions. Exposure to severe haze pollution and experiencing harms from it were key factors influencing public willingness to respond to haze. These results reflected individual exposure levels correlating closely with risk perception and acceptance of PM2.5. However, a crucial gap exists between public acceptable risk levels (PARL) of air pollution and the policy objectives of the State Council's Action Plan. Thus, policymakers can utilize this study to develop more targeted measures to combat air pollution.

Bovine Serum Albumin Adsorption in Mesoporous Titanium Dioxide: Pore Size and Pore Chemistry Effect.

Understanding the mechanism of protein adsorption and designing materials with high sensitivity, high specificity and fast response are critical to develop the next-generation biosensing and diagnostic platforms. Mesoporous materials with high surface area, tunable pores, and good thermal/hydrostatic stabilities are promising candidates in this field. Because of the excellent biocompatibility, titanium dioxide has received an increasing interest in the past decade for biomedical applications. In this work, we synthesized mesoporous titanium dioxide with controlled pore sizes (7.2-28.0 nm) and explored their application for bovine serum albumin (BSA) adsorption. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption/desorption experiments were performed to characterize the mesoporous TiO2 samples before and after BSA adsorption. Isothermal microcalorimetry was applied to measure both the adsorption heat and conformation rearrangement heat of BSA in those mesopores. We also carried out thermogravimetry measurements to qualitatively estimate the concentration of hydroxyl groups, which plays an important role in stabilizing BSA in-pore adsorption. The adsorption stability was also examined by leaching experiments. The results showed that TiO2 mesopores can host BSA adsorption when their diameters are larger than the hydrodynamic size of BSA (∼9.5 nm). In larger mesopores studied, two BSA molecules were adsorbed in the same pores. In contrast to the general understanding that large mesopores demonstrate poor stabilities for protein adsorptions, the synthesized mesoporous TiO2 samples demonstrated good leaching stabilities for BSA adsorption. This is probably due to the combination of the mesoporous confinement and the in-pore hydroxyl groups.

[Analysis on DNA methylation of mosaic and moxa type leaves of Aconitum carmichaeli by MSAP].

An MSAP analysis method was established for detecting DNA methylation of Aconitum carmichaeli leaves, and the DNA methylation of different leaf shapes and different leaf position was analyzed by MSAP. The study made experiments on the leaves of different position of mosaic and moxa leaf type A. carmichaeli, researched the effects of restriction digestion of genomic DNA by using two restriction enzymes, screened the suitable selective amplification primers, and analyzed the methylation differences of leaves by calculating the 6% acrylamide gel electrophoresis bands and lane. The best reaction system of MSAP was obtained, under the conditions of 37 ℃, the 16 h incubated time was more suitable for 150 ng DNA, and 25 pairs of selective amplification primers were selected from 256 pairs. Totally, 273 electrophoresis bands were obtained by 25 pairs of selective primers, including 228 non methylation or single chain methylation bands,27 double chain methylation bands,and 18 single stranded methylation bands, the total methylation rate was 16.48%. The methylation rate was slightly different in mosaic and moxa leaf type A. carmichaeli leaf, which were 15.36%, 14.34%, respectively, and article 8, article 6 nucleotide fragments of genome methylation modification differences were obtained, accounted for 3%, 2.26% of the total number of bands. Based on this study it can provide new ideas for molecular identification, breeding and cultivation, and genetic evolution of A. carmichaeli.

Panax ginseng and its ginsenosides: potential candidates for the prevention and treatment of chemotherapy-induced side effects.

Chemotherapy-induced side effects affect the quality of life and efficacy of treatment of cancer patients. Current approaches for treating the side effects of chemotherapy are poorly effective and may cause numerous harmful side effects. Therefore, developing new and effective drugs derived from natural non-toxic compounds for the treatment of chemotherapy-induced side effects is necessary. Experiments in vivo and in vitro indicate that Panax ginseng (PG) and its ginsenosides are undoubtedly non-toxic and effective options for the treatment of chemotherapy-induced side effects, such as nephrotoxicity, hepatotoxicity, cardiotoxicity, immunotoxicity, and hematopoietic inhibition. The mechanism focus on anti-oxidation, anti-inflammation, and anti-apoptosis, as well as the modulation of signaling pathways, such as nuclear factor erythroid-2 related factor 2 (Nrf2)/heme oxygenase-1 (HO-1), P62/keap1/Nrf2, c-jun N-terminal kinase (JNK)/P53/caspase 3, mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinases (ERK), AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR), mitogen-activated protein kinase kinase 4 (MKK4)/JNK, and phosphatidylinositol 3-kinase (PI3K)/AKT. Since a systemic review of the effect and mechanism of PG and its ginsenosides on chemotherapy-induced side effects has not yet been published, we provide a comprehensive summarization with this aim and shed light on the future research of PG.

Adhesion and friction forces in biofouling attachments to nanotube- and PEG- patterned TiO2 surfaces.

The TiO2 nanotube pattern with features down to 20nm (TN20) is highly and efficiently resistant to fibrinogen and S. aureus attachment. The ability of TN20 to resist biofouling adsorption, is due to low biofouling-surface adhesion force that determines the initial biofouling attachment, as well as the low friction coefficient that enables a complete removal of biofouling from a low-adhesive 'repelling' TN20 substrate under fluid flow. By grafting PEG molecules onto TN20, a significantly higher S. aureus cells attachment was observed, because of the stronger adhesion forces originated from the deformation of the soft PEG coatings. The complete interaction of S. aureus on structure-free dense TiO2 (DT), yields larger contact area and thus higher adhesion force than on any other TiO2 surfaces, resulting in a high coverage of bacteria. The existing high friction coefficient of S. aureus on TN80 (TiO2 with 80nm nanotubular size) and TN80-P (PEG-modified TN80), due to the much greater surface roughness, would contribute to the immobilization of biofouling on the surface under fluid flow, even though the two surfaces exhibit low adhesion forces. The analysis of adhesion and friction forces manipulated by TiO2 nanotubular topography and posted PEG patterns, advances our understanding of the mechanisms by which nanotopography patterned surfaces reduce biofouling attachment.

[Detecting the DNA damage of N-ras gene induced by potassium dichromate].

OBJECTIVE: Applying RDPCR to detect the DNA damage of N-ras gene induced by Potassium dichromate METHODS: Preparing single-stranded probes of exon 1 of N-ras gene in human. The genomic DNA was treated with Potassium dichromate, then amplified by RDPCR and detected by Southern hybridization with the probe. RESULTS: The clear hybridized bands can be seen in the position which is induced by Potassium dichromate on the dose of 100 micromol/L, but can't be detected on the dose over 1000 mol/L. CONCLUSION: It indicates that Potassium dichromate can cause the DNA damage of N-ras gene, which should be the key point of its carcinogenesis mechanisms.

[Application with single-stranded probes in randomized terminal linker-dependent PCR].

OBJECTIVE: Preparing single-stranded (ss) probes in place of double-stranded (ds) probes to improve the hybridization efficiency and specificity of randomized terminal linker-dependent PCR (RDPCR). METHODS: Using asymmetric PCR and single-primer PCR to prepare ss probes of extron 7 of p53 gene in rat, then comparing the results hybridized with ss probes and ds probes. RESULTS: Preparation of ss probes by asymmetric PCR and single-primer PCR gets success. Hybridization results showed that the ss probes could get better signals and less noise than ds probes. CONCLUSION: In comparison with ds probes, the application of ss probes can increase the hybridization sensitivity and specificity of RDPCR.

[Establishing a method to detect the DNA damage of N-ras gene].

OBJECTIVE: Applying RDPCR to detect the DNA damage of N-ras gene in human. METHODS: Single-primer PCR was used to prepare single strand (ss) probes of extron 1 of N-ras gene in human. The genomic DNA was digested completely by restriction endonuclease, then amplified by RDPCR and detected by Southern hybridization with the probe. RESULTS: The ss probes were successfully prepared by single-primer PCR. The hybridized bands were clearly seen in the expected migration positions. CONCLUSION: The result shows that the method to detect the damaged position of N-ras gene has been established, which would be helpful to further studies on chemical carcinogenesis and on the prevention of tumor.