Human health risk assessment based on a total diet study of daily mercury intake in Chengdu, China.

To assess the total daily mercury intake and main exposure sources of residents, six food groups, including marine fish, freshwater fish, poultry, livestock, vegetables, and cereals, were collected from five districts of Chengdu, China. The median concentrations of total mercury (THg) and methylmercury (MeHg) were 12.8 and 6.94 µg kg-1 ww, respectively. Cereals (32.2%), vegetables (30.5%), and livestock (16.2%) contributed to a much larger extent to the total consumption for the participants in Chengdu. All food categories that contributed the most of THg (2.16 µg day-1) and MeHg 1.44 (µg day-1) to the daily intake in Chengdu were cereals and marine fish, respectively. The total Hazard Ratios values below 1 in this study indicate that there is no health risk associated with Hg ingestion from the consumption of these foods for the residents in Chengdu.

[Extracorporeal shock wave therapy for chronic prostatitis / chronic pelvic pain syndrome: A meta-analysis].

OBJECTIVE: To systematically evaluate the clinical efficacy of the extracorporeal shock wave therapy (ESWT) in the treatment of chronic prostatitis / chronic pelvic pain syndrome (CP/CPPS) and provide some evidence for the management of the disease. METHODS: We searched the PubMed, Cochrane Library, EMbase, CNKI, VIP, WanFang Data and CBM databases on the internet, as well as the Journal of Clinical Urology and Chinese Journal of Urology manually for randomized controlled trials (RCT) on the treatment of CP/CPPS by ESWT published from their establishment till February 1, 2019. Two reviewers independently screened the literature, extracted the data and assessed the risk of bias of the included studies, followed by a meta-analysis with the RevMan 5.3 software. RESULTS: Totally 12 RCTs involving 838 CP/CPPS patients were included in this study. Compared with the controls, the patients treated by ESWT showed a significantly higher rate of overall effectiveness (OR = 8.75, 95% CI: 5.16 to 14.86, P < 0.000 01) and lower NIH-CPSI scores (MD = －5.10, 95% CI: －6.13 to －4.06, P < 0.000 01). Subgroup analyses manifested that a higher number of shock wave pulses (≥2 000) had a better therapeutic effect (MD = －4.99, 95% CI: －6.20 to －3.38, P < 0.000 01 in the >2 000-pulse group; MD = －5.76, 95% CI: －7.09 to －4.42, P < 0.000 01 in the 2 000-pulse group). CONCLUSIONS: ESWT can raise the rate of overall clinical effectiveness and improve the symptoms of chronic prostatitis in the treatment of CP/CPPS. This conclusion, however, is to be further supported by more RCTs with higher quality, larger sample size and better design.

Theoretical and experimental research on self-assembly system of molecularly imprinted polymers formed via chloramphenicol and methacrylic acid.

Chloramphenicol was chosen as the imprinting molecule and the methacrylic acid was chosen as the functional monomer to prepare molecularly imprinted polymers. Ethylene glycol dimethacrylate, pentaerythritol triacrylate, and trimethylolpropane trimethylacrylate were used as the cross-linking agents, respectively. The interaction processes between chloramphenicol and methacrylic acid were simulated by using the ωB97XD/6-31G (d,p) method. The self-assembled configuration, bonding sites, binding number, binding energy, and interaction principle of stable complex formed by chloramphenicol and methacrylic acid with different molar ratios have been studied. The selectivity of the most stable complex formed from chloramphenicol and methacrylic acid was discussed with the thiamphenicol and florfenicol as the analogues of chloramphenicol. The results showed that chloramphenicol and methacrylic acid were interacted through the hydrogen bonds. When the molar ratio was 1:10 and pentaerythritol triacrylate as the cross-linking agent, the ordered complex formed by chloramphenicol and methacrylic acid has the largest amount of hydrogen bonds and the lowest binding energy. Scatchard analysis showed that the maximum apparent adsorption capacity was 173.3 mg/g (0.536 mol/g), and the selection factor of florfenicol was the largest. This study provides a reliable theoretical and experimental basis for the design, preparation, and characterization of chloramphenicol molecularly imprinted polymers.

Occurrence and distribution of phthalate esters in freshwater aquaculture fish ponds in Pearl River Delta, China.

The concentrations, congener profiles and spatial distribution of 13 phthalate esters (PAEs) in the freshwater fish ponds in the Pearl River Delta (PRD) region were investigated in water and sediment samples collect from 22 sites during Jul. 2016-Sept. 2017. The di-2-ethylhexyl phthalate (DEHP) was the predominant compounds in both water and sediment samples, accounting for 70.1% and 66.1% of ∑PAEs, respectively. The DEHP concentrations in the water samples collected from the sites of Zhongshan (35.7 µg/L), Jingmen (17.3 µg/L) and Nanhai (14.2 µg/L) were higher than that collected from other sampling sites (p <0.05), and exceed the Chinese environmental quality standards for surface water (DEHP, 8.00 µg/L). The concentrations of ΣPAEs (mean and median were 11.8 mg/kg dw and 7.95 mg/kg dw) in sediment was higher than that in sediment of river and estuary in the PRD region (p <0.05). The median concentrations of DEHP and di-n-butyl phthalate (DBP) exceeded recommend environmental risk limit (ERL) that posed a potential risk to the aquaculture fish pond environment in the PRD.

Theoretical and experimental studies on the performances of barbital-imprinted systems.

By using density functional theory, we studied the interaction process between barbital and 2-vinyl-4,6-diamino-1,3,5-triazine in acetonitrile at 333 K. Barbital and 2-vinyl-4,6-diamino-1,3,5-triazine were used as the template and functional monomer, respectively. The molecularly imprinted polymer microspheres containing barbital and 2-vinyl-4,6-diamino-1,3,5-triazine were synthesized through precipitation polymerization. After removing the template molecule barbital, the average diameter of the obtained molecularly imprinted polymers was 1.45 µm. By optimizing the molar ratio of barbital and the 2-vinyl-4,6-diamino-1,3,5-triazine, the resulting molecularly imprinted polymers showed the highest adsorption for the barbital. The analysis of the Scatchard plot revealed that the dissociation constant (Kd ) and apparent maximum adsorption quantity (Qmax ) of the molecularly imprinted polymers were 30.69 mg/L and 8.68 mg/g, respectively. The study of selective adsorption showed that molecularly imprinted polymers exhibited higher selectivity for barbtital than that for 1,3-dimethyl barbituric acid and pentobarbital. Herein, the studies can provide theoretical and experimental references for the barbital-imprinted system.

Preparation of melamine molecularly imprinted polymer by computer-aided design.

Melamine was chosen as template, methacrylic acid was chosen as functional monomer, and divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane trimethylacrylate were chosen as cross-linking agents, respectively. The WB97XD/6-31G(d, p) method was used to calculate the geometry optimization of the different imprinting ratios, the action sites, the bonding situation, and the optimization of the cross-linking agents. The nature of the imprinting effect was also studied by the atoms in molecules theory. The theoretical results showed that melamine interacts with methacrylic acid by hydrogen bonding, and the melamine molecularly imprinted polymers with a molar ratio of 1:6 have the most hydrogen bonds and the most stable structure. Divinylbenzene is the best cross-linking agent for the melamine molecularly imprinted polymers. The melamine molecularly imprinted polymers were synthesized by precipitation polymerization. The results showed that the maximum adsorption capacity for molecularly imprinted polymers towards melamine is 19.84 mg/g, and the adsorption quantity of the polymers to melamine is obviously higher than that of cyromazine, cyanuric acid, and trithiocyanuric in milk. This study could provide theoretical and experimental references for the screening of the imprinting ratio and the cross-linking agent for the given template and monomer system.

[Development of one corn ear and verification the three laws of inheritance].

A new corn was developed as a lab material to verify the three Laws of Inheritance on only one F2 ear with correct segregation ratios of kernel traits. In order to investigate the three Inheritance Laws simultaneously with one ear, the sweet endosperm (Sn1), kernel color (C1) and the glutinous endosperm (Wx) were chosen as the original phenotypes. Gene Sn1sn1 is located on chromosome four, genes C(1c1) and Wxwx are located on chromosome nine. After several generations of continuous self-pollination and test crossing, direct crossing and back crossing, with strict selections, the homozygous parents were obtained. With different combinations of homozygous parents, different hybrids were developed. The segregation ratios of each phenotype on the same F2 ear are compared to the theoretical segregation ratios according to the corn gene exchange and gamete types and quantities produced through meiosis. The results showed three ratios of 3:1, two ratios of 9:3:3:1, and one ratio of linkage and exchange, with all the chi-square values smaller than the permitted ones. This means that only one ear of this new hybrid corn can be used as a new teaching aid to examine and verify the three Laws of Inheritance.

[Preparation and identification of the oligonucleotide chip for detecting the virulence-associated genotypes and drug resistance of Helicobacter pylori].

OBJECTIVE: To develop an oligonucleotide microarray-based method for the simultaneous detection of Helicobacter pylori (Hp) infection, virulence-associated genotypes, and drug resistance. METHODS: Hp was classified into cagA + and cagA- genotypes based on its virulence. Clarithromycin-resistance of Hp was identified by existence of point mutations in 23S rRNA. We constructed an oligonucleotide microarray chip to simultaneously diagnose Hp infection and detect its virulence-associated genotypes and mutations associated with clarithromycin-resistance. The diagnostic accuracy of the constructed microarray was tested with templates of wild type and mutated type. RESULTS: The oligonucleotide chip accurately detected cagA + and cagA- genotypes of Hp, as well as four common point mutations in 23S rRNA related to clarithromycin-resistance. CONCLUSION: Oligonucleotide microarray chip can be used to diagnose Hp infection and test its virulence-associated genotypes and drug resistance simultaneously.

[Detection of P53 and K-ras gene mutations in lung cancer with oligonucleotide chip].

Different factors including hybridization solution components, hybridization temperature, and the concentration and proportion of the labelled primer, which affected the sensitivity and specificity of single mutation identification, were exploited. Asymmetric PCR increased the hybridization sensitivity, and the asymmetric multi-PCR did not affect the specificity, while the sensitivity was improved a little. Among 30 lung cancer samples detected with the oligonucleotide microarray, 12 was found P53 gene mutations and 5 had K-ras gene mutations. The P53 gene mutations identified by the oligonucleotide microarray was proved 80% same as the sequencing results. The obvious statistical relations of K-ras and P53 gene mutations with tumor type, tumor stage and smoking were not obtained because of less samples and mutation sites.