Biomedical and environmental sciences : BES最新文献

Objective: To develop a high-throughput screening assay for Farnesoid X receptor (FXR) agonists based on mammalian one-hybrid system (a chimera receptor gene system) for the purpose of identifying new lead compounds for dyslipidaemia drug from the chemical library.

Methods: cDNA encoding the human FXR ligand binding domain (LBD) was amplified by RT-PCR from a human liver total mRNA and fused to the DNA binding domain (DBD) of yeast GAL4 of pBIND to construct a GAL4-FXR (LBD) chimera expression plasmid. Five copies of the GAL4 DNA binding site were synthesized and inserted into upstream of the SV40 promoter of pGL3-promoter vector to construct a reporter plasmid pG5-SV40 Luc. The assay was developed by transient co-transfection with pG5-SV40 Luc reporter plasmid and pBIND-FXR-LBD (189-472) chimera expression plasmid.

Results: After optimization, CDCA, a FXR natural agonist, could induce expression of the luciferase gene in a dose-dependent manner, and had a signal/noise ratio of 10 and Z' factor value of 0.65.

Conclusion: A stable and sensitive cell-based high-throughput screening model can be used in high-throughput screening for FXR agonists from the synthetic and natural compound library.

Objective: To establish a fast and sensitive method for the detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in precision-cut rat liver slices by HPLC-MS/MS and to investigate isoniazid (INH) -induced oxidative DNA damage.

Methods: Precision-cut liver slices (300 microm) were prepared from male rats, and incubated with INH (0.018 mol/L) for 2 h after 1 h preincubation. DNA in the slices was extracted and digested into free nucleosides at 37 degrees C. The samples were injected into HPLC-MS/MS after the proteins were removed. The level of oxidative DNA damage was estimated using the ratio of 8-OHdG to deoxyguanosine (dG).

Results: The limit of detection of 8-OHdG was 1 ng/mL (S/N=3) and the intra-assay relative standard variation was 3.38% when one transition 284.3/168.4 was used as a quantifier and another two transitions 284.3/140.2, 306.1/190.2 as qualifiers. 8-OHdG and dG were well separated, as indicated by elution at 10.02 and 7.37 min, respectively. INH significantly increased the ratio of 8-OHdG to dG in rat liver slices (P<0.05).

Conclusion: 8-OHdG in precision-cut liver slices could be sensitively determined by HPLC-MS/MS. HPLC-MS/MS coupled with precision-cut tissue slices is a fast and reliable analytical technique to evaluate oxidative DNA damage of target tissues caused by procarcinogens and cytotoxins.

Objective: During present investigation the data of a laboratory-scale anoxic sulfide oxidizing (ASO) reactor were used in a neural network system to predict its performance.

Methods: Five uncorrelated components of the influent wastewater were used as the artificial neural network model input to predict the output of the effluent using back-propagation and general regression algorithms. The best prediction performance is achieved when the data are preprocessed using principal components analysis (PCA) before they are fed to a back propagated neural network.

Results: Within the range of experimental conditions tested, it was concluded that the ANN model gave predictable results for nitrite removal from wastewater through ASO process. The model did not predict the formation of sulfate to an acceptable manner.

Conclusion: Apart from experimentation, ANN model can help to simulate the results of such experiments in finding the best optimal choice for ASObased denitrification. Together with wastewater collection and the use of improved treatment systems and new technologies, better control of wastewater treatment plant (WTP) can lead to more effective maneuvers by its operators and, as a consequence, better effluent quality.

Objective: The wetland at Dalian Bay in the Northeast of China has been polluted by oil severely. The effect of various microbes and operation parameters on the bioremediation of oil-polluted wetlands at Dalian Bay was investigated and reported previously. In the study, other operation conditions related to the status of medium were investigated via statistical experimental design and analysis and a necessary information is involved to use micro-technology in the application.

Methods: The method used involved the direct inoculation of selected bacteria, which were capable of degrading oil. The operation conditions were further optimized and evaluated by gravimetrical assay.

Results: The optimal pH and temperature for the studied bacteria to degrade the existing oil pollutants were established as pH 8.0 and 27 degrees C. The mixed of various bacteria showed better results in terms of oil degradation than any single one. Among the selected four factors, disturbance, oxidant, nutrients, and biosurfactant, the former two contributed more impacts on the oil degradation in the early stage of process, while the latter two became the limiting factors in the late stage. Three sets of optimal conditions were obtained for each individual stage, but no one was suitable for the overall process.

Conclusion: The study demonstrated the technical feasibility of using direct inoculation into the contaminated soil samples to remove oil pollutants. It suggested that the operation conditions should be monitored and adjusted during the different stages of bio-reactions in the process to achieve the best result of oil degradation.

Objective: To evaluate the correlation between the beta-fibrinogen gene-455G/A polymorphism and cerebral infarction in Chinese population by means of meta-analysis.

Methods: Genetic association studies on evaluating the beta-fibrinogen gene -455G/A polymorphism and cerebral infarction involving Chinese population published before December 2005 were collected from database of PubMed, EMBASE, and CNKI. All the data in literature were abstracted based on the defined selection criteria by two independent investigators. Publication bias was tested by funnel plot and the odd ratios of all studies were combined dependent on the result of heterogeneity test among the individual studies. The software Review Manager (Version 4.2) was used for meta-analysis.

Results: Eleven studies including 1405 patients and 1600 controls met the selection criteria. There was no publication bias in 11 reviewed studies. Heterogeneity test of reviewed studies showed statistically significant differences (chi2=24.58, P=0.006) among the ORs of individual studies. The combined OR of 11 studies of susceptibility to cerebral infarction in -455A allele carriers compared with the -455G/G wild homozygotes was 1.33 (95%CI 1.04-1.71, P=0.02). In the patients with cerebral infarction in 6 studies, the summarized average plasma fibrinogen level of allele A carrier was 0.29 g/L (95%CI 0.14-0.44, P=0.0002) higher than that of -455G/G homozygous ones.

Conclusions: beta-fibrinogen gene -455G/A polymorphism might contribute to susceptibility of cerebral infarction in Chinese population; allele A increases the individual susceptibility to the disease.

Objective: To study the adsorption of 5-Amino-2-chlorotoluene-4-sulfonic (CLT) and chlorhydric (HC1) acids from wastewater by weakly basic resin.

Methods: The kinetics and isotherm were studied. Thermodynamic parameters for the adsorption of acids were calculated and discussed.

Results: The adsorption of CLT and HC1 acids followed Langmuir isotherm and the first-order kinetics model.

Conclusion: The adsorptive affinity of the two acids on D301R is in the order of CLT acid > HCl acid. CLT and HCl acids can be separated.

Objective: To introduce synergetic inactivation of microorganisms in drinking water by short-term free chlorination for less than 15 minutes followed by monochloramination.

Methods: Indicator microorganisms such as Escherichia coli, Staphylococcus aureus, Candida albicans, and spores of Bacillus subtilis were used to assess the efficiency of sequential chlorination and free chlorination.

Results: The sequential chlorination was more efficient in inactivating these microorganisms than free chlorination, indicating that synergy was provided by free chlorine and monochloramine. Ammonia addition time, temperature and pH had influences on this synergy.

Conclusions: The possible mechanism of this synergy might involve three aspects: free chlorine causing sublethal injury to microorganisms and monochloramine further inactivating them; different ability of free chlorine and monochloramine to penetrate and inactivate microorganism congeries; and higher concentration of residual chlorine in sequential chlorination than in free chlorination.

Objective: To investigate the relation between air pollution exposure and preterm birth in Shanghai, China.

Methods: We examined the effect of ambient air pollution on preterm birth using time-series approach in Shanghai in 2004. This method can eliminate potential confounding by individual risk factors that do not change over a short period of time. Daily numbers of preterm births were obtained from the live birth database maintained by Shanghai Municipal Center of Disease Control and Prevention. We used the generalized additive model (GAM) with penalized splines to analyze the relation between preterm birth, air pollution, and covariates.

Results: We observed a significant effect of outdoor air pollution only with 8-week exposure before preterm births. An increase of 10 microg/m3 of 8-week average PM10, SO2, NO2, and O3 corresponded to 4.42% (95%CI 1.60%, 7.25%), 11.89% (95%CI 6.69%, 17.09%), 5.43% (95%CI 1.78%, 9.08%), and 4.63% (95%CI 0.35%, 8.91%) increase of preterm birth. We did not find any significant acute effect of outdoor air pollution on preterm birth in the week before birth.

Conclusion: Ambient air pollution may contribute to the risk of preterm birth in Shanghai. Our analyses also strengthen the rationale for further limiting air pollution level in the city.

Objective: To investigate reductive dechlorination of 4-chlorophenol (4-CP) by nanoscale Fe0 under different conditions.

Methods: Nanoscale Fe0 was synthesized by using reductive method. 4-CP and its intermediate products were analyzed by HPLC. Chlorine ion was quantified with DX-100 ion chromatograph. Nano-iron particles were observed under a FEI Quanta 200 FEG environmental scanning electron microscope (ESEM).

Results: The size of the particles was in the range of 10-100 nm. The nano-iron particles could reduce 4-CP effectively. The initial concentration of 4-CP increased with the decrease of the relative degradation rate, whereas the reduced amount of 4-CP increased. Temperature could influence both the dechlorination rate and the reaction pathway. Moreover, the stability and durability of nanoscale Fe0 was evaluated through batch studies over extended periods of time.

Conclusion: The nanoscale Fe0 can be used for sustainable treatment of contaminants in groundwater.

Objective: To investigate the feasibility of nitrogen and phosphorus recovery from swine waste biogas digester effluent and the effects of pH and NH4+: Mg2+: PO4(3-) molar ratio on its precipitation.

Methods: Precipitation experiments with swine waste biogas digester effluent were conducted at pH 7.5, 8.0, 8.5, and 9.0 together with NH4+: Mg2+: PO4(3-) molar ratios 1: 0.2: 0.08, 1: 1: 1, and 1: 1.5: 1.5. Chemical and X-ray diffraction (XRD) analysis were done to determine the composition of the precipitate.

Results: The highest removal and recovery of NH4+ and PO4(3-) were achieved at pH 9.0 in each experiment. The elevation of pH to 9.0 alone could decrease the initial PO4(3-) concentration from 42 mg L(-1) to 4.7 mg L(-1) and 89.2% PO4(3-) recovery was achieved. The pH-molar ratio combination 9.0-1: 1.5: 1.5 effected 76.5% NH4+ and 68.5% PO4(3-) recovery. The molar ratio of 1: 1: 1 together with pH elevation to 9.0 was determined to be the optimum combination for both NH4+ and PO4(3-) removal as it recovered over 70% and 97% of the initial NH4+ and PO4(3-), respectively.

Conclusions: Nitrogen and phosphorus can be recovered from biogas digester effluent as struvite.