[Determination of acetone in urine by headspace gas chromatography-mass spectrometry].

Objective: To establish a method for determination of acetone in urine by headspace gas chromatography-mass spectrometry. Methods: From March to June 2021, the 3.0 ml urine sample was placed in a headspace bottle with 4.0 g of anhydrous sodium sulfate and sealed. Equilibration time was 30 min at 85 ℃. The separation was carried out on a DB-5MS column. The urine sample was detected by mass spectrometry and quantified by external standard method. Results: The method for the determination of acetone in urine by headspace gas chromatography-mass spectrometry had good linearity in the range of 51.2-1024.0 µg/L, and the correlation coefficient was 0.9995. The detection limit and the lower limit of quantification of acetone were 16.4 µg/L and 54.6 µg/L. The average recoveries of samples ranged from 94.9% to 96.8%. The intra-assay precision and inter-assay precision were both less than 10%. Samples can be stored at least 7 d at 4 ℃ or -20 ℃. Conclusion: This method has simple sample preparation and high sensitivity. It can be used for monitoring and evaluation of urinary acetone in the general population and occupationally exposed populations.

[Determination of phenylglyoxylic acid and mandelic acid in urine by ultra high performance liquid chromatography tandem mass spectrometry].

Objective: To develop a method for the analysis of phenylglyoxylic acid (PGA) and mandelic acid (MA) in urine by ultra-high performance liquid chromatography tandem mass spectrometry. Methods: The study was conducted in April 2022. Urine samples were directly diluted with the initial mobile phase, separated by Waters HSS T3 column after passing through the membrane, and analyzed under negative ionization mode (ESI(-)) and multiple reaction monitoring (MRM) conditions, the contents of PGA and MA in human urine were quantitatively determined by external standard method. Results: The determination of PGA and MA showed a good linear relationship within the range of 10-1000 ng/ml, with a correlation coefficient of 0.9999. The linear regression equation of PGA was y=1141.4x+2157.3, the detection limit and lower limit of quantification of the method were 0.081 ng/ml and 0.269 ng/ml, and the recovery rate was 90.47%-99.83%. The linear regression equation of MA was y=62.8x+140.3, the detection limit and lower limit of quantification of the method were 0.551 ng/ml and 1.836 ng/ml, and the recovery rate was 92.75%-101.09%. The intra and inter batch precision of PGA and MA were both<5%. Conclusion: An ultra-high performance liquid chromatography tandem mass spectrometry method for the analysis of PGA and MA in urine was established.The sample pretreatment operation is simple, and the accuracy and precision of the method meet the standard requirements. It can be used for monitoring and evaluating PGA and MA in urine of the general population and occupational contact population.

[Survey on the cognition of the "undetectable equals untransmittable" concept among HIV-infected men who have sex with men receiving antiviral treatment].

Objective: To explore the cognition of the "undetectable equals untransmittable" ("U=U") concept and associated factors among HIV-infected men who have sex with men (MSM) receiving antiviral treatment (ART) in Shenzhen, and provide evidence for designing promotion and advocacy strategies for the "U=U" concept. Methods: We recruited HIV-infected MSM receiving ART using convenient sampling method combined with routine follow-up in Shenzhen through conducting observational survey. The sample size was estimated to be 475. A questionnaire was administered to collect socio-demographic characteristics, sexual behaviors, ART, viral load testing and the cognition towards "U=U" in HIV-infected MSM. Logistic regression was used to access factors associated with acceptance of "U=U". Results: A total of 490 HIV-infected MSM receiving ART were recruited. Of whom, 60.2% (295/490) were aware of "U=U" and 50.6% (248/490) accepted "U=U". Multiple logistic regression showed that participants who had an educational level of college or above (aOR=1.76,95%CI: 1.12-2.75) were more likely to accept "U=U". Those who had no local residency (aOR=0.51,95%CI: 0.29-0.92), had viral load >0 copies/ml in the last testing (aOR=0.61,95%CI: 0.38-0.98) and were unaware of "U=U" (aOR=0.13, 95%CI: 0.09-0.21), were less likely to accept "U=U". Conclusions: HIV-infected MSM receiving ART had a low cognition level of "U=U" in Shenzhen. Promotion and advocacy on this concept through healthcare workers should be enhanced in combination with routine follow-up in order to improve their ART adherence and outcome of treatment. Furthermore, developing related guidelines on "U=U" according to the characteristics of HIV-infected individuals is warranted to improve the normalization of promotion and advocacy on "U=U".

[Evaluation of effects of comprehensive intervention based on key persons on AIDS-related high-risk behaviors in male sex workers in entertainment venues].

Objective: To evaluate the effect of comprehensive intervention model based on key persons in entertainment venues on the incidence of AIDS-related high-risk behaviors in male sex workers (MSW). Data from this study thus can be used to provide compelling evidence for the wider implementation of the intervention model. Methods: In this randomized controlled trial, MSW were recruited and followed-up from May to December, 2021 in entertainment venues in Wuxi, Jiangsu Province, with an estimated sample size of 320. The MSW in the intervention group were provided with comprehensive interventions via key persons in entertainment venues compared with the control group receiving routine interventions. The effect of the intervention model was assessed by comparing the behavioral differences between these two groups and in the intervention group before and after intervention. Results: A total of 330 MSW were recruited at baseline survey, in which 168 were divided into intervention group and 162 into control group. There was no significant difference in socio-demographic characteristics between two groups (all P>0.05). After intervention for 6 months, the rate of consistent condom use in commercial homosexual activities in the intervention group was 79.5% (101/127), higher than 63.2% (74/117) in the control group, and in the intervention group, 90.1% (73/81) of MSW used condom consistently in heterosexual activities, higher than in the control group (59.6%, 59/99) . Compared with 30.8% (36/117) of MSW with drug abuse history in the control group, a lower proportion of 9.4% (12/127) was observed in the intervention group. Differences in all of aforementioned variables were significant (all P<0.05). After intervention, the incidence of group sex was 3.9% (5/127) in the intervention group and 9.4% (11/117) in the control group, the incidence of anal sex post-alcohol consumption was 40.2% (51/127) in the intervention group and 32.5% (38/117) in control group, the differences were not significant (all P>0.05). Conclusions: The intervention model based on key persons in entertainment venues could promote consistent condom use in MSW in both commercial homosexual and heterosexual activities and help them reduce drug abuse, but had no significant effect on decreasing group sex and anal sex after alcohol consumption. It is crucial to improve the intervention model according to the specific characteristics of MSW in order to enhance the effects of comprehensive intervention.

[A non-targeted metabolomics study on serum of occupational people exposed with nanometer titanium dioxide particles (TiO(2)-NPs)].

Objective: To study the changes of serum metabolic profile of occupational people exposed with nanometer titanium dioxide particles (TiO(2)-NPs), and to explore the biomarkers and injury mechanism of TiO(2)-NPs health effects. Methods: From June 2020 to June 2021, a TiO(2)-NPs production enterprise was selected as the research site by a typical sampling method, 64 people in the TiO(2)-NPs exposure group were selected from the enterprise, and 62 people of the logistics administrative staff in the same enterprise were selected as the control group, and blood samples were collected using non-anticoagulant blood collection tubes. After the samples were methanol-precipitated, the untargeted metabolomic data was collected by ultra-high performance liquid chromatography time-of-flight mass spectrometry, and biomarkers were screened and metabolic pathway analysis was performed. Results: 46 different metabolites were screened out by P<0.05 and variable importance projection index (VIP) value >1, mainly including glycerides, sphingomyelin, glycerophospholipid, fatty acyl, etc.; By ROC analysis to determine 3-hydroxy-4, 5-dimethyl-2 (5H) - furanone, 4-aminobiphenyl, heptanoylcarnitine, Hexadecanedioic acid mono-L-carnitine ester, Ibutilide, LysoPA (18∶1 (9Z) /0∶0), LysoPC (18∶0), PC (16∶0/16∶0), PC (16∶0/20: 4 (5Z, 8Z, 11Z, 14Z) ), PC (P-18∶1 (9Z) /P-18∶1 (9Z) ) 10 candidate biomarkers; involving changes in 4 metabolic pathways, namely glycerophospholipid metabolism, sphingolipid metabolism, phenylalanine, tyrosine and tryptophan acid biosynthesis, linoleic acid metabolism. Conclusion: Occupational exposure to TiO(2)-NPs has a significant impact on serum metabolic profiles.

[Relationships between lead-induced learning and memory impairments and gut microbiota disturbance in mice].

Objective: To explore the effect of lead exposure on the neurobehavior and gut microbiota community structure in mice. Methods: In August 2019, 64 C57BL/6 mice were randomly divided into 4 groups: control group (0 ppm) , low lead exposure group (20 mg/l) , medium lead exposure group (100 mg/l) and high lead exposure group (500 mg/l) . During the experiment, they were free to eat and drink. The drinking water of the lead exposure group was mixed with lead acetate, and sodium acetate was added in the control group. After 10 weeks of exposure, the Morris water maze was used to test the learning and memory ability of each group of mice, and then they were sacrificed for sampling. ICP-MS was used to detect lead content in whole blood and brain tissue. ELISA was used to determine the level of IL-1ß in mouse serum. 16S rRNA sequencing was used to detect the structural diversity of the intestinal flora in feces, and then the correlation between the flora and behavior indicators was analyzed. Results: In the Morris water maze experiment, compared with the control group, there was no significant difference in the body weight and swimming speed of the mice in the lead exposure groups. The escape latency of the mice in the 100 mg/l and 500 mg/l dose groups was prolonged, and the number of platform crossings decreased (P<0.05) ; meanwhile, the staying time of the mice in the 500 mg/l Pb-treated group in the target quadrant was lower than that of the control group, and the difference was statistically significant (P<0.05) . Compared with the control group, the blood lead content of the mice in each lead exposure group was significantly increased, and the brain lead content of mice in the 500 mg/l dose group was significantly elevated (P<0.05) . The serum IL-1ß levels of mice in each lead exposure group were higher than those of the control group (P<0.05) . At the phylum level, the relative abundance of the Proteobacteria phylum in all of Pb-treated groups was significantly increased (P<0.05) ; at the genus level, Allobaculum, Desulfovibrio, Lachnospiraceae_NK4A136_group, Turicibacter and Ureaplasma were significantly increased (P<0.05) . Among them. The relative abundance of Desuffaoibrio, Turici bacter, and Ureaplasma was negatively correlated with the residence time of mice in the quadrant of the platform (r=-0.32, -0.29, -0.44, P<0.05) . Conclusion: Lead exposure induced learning and memory impairments in mice, which may be related to the disturbance of the gut microbiota.

[Effect of shift work on menopausal age and menstruation span of professional women].

Objective: To explore the relationship between shift work and menopausal age and menstruation span of retired women. Methods: During July 2017 and October 2018, the research was performed by using cluster sampling in nine districts of Shenzhen City to select all permanent residents (3518 people) with Shenzhen household registration in which was equal to or over 60 years old from the Community Health Service Centers. The data of age, marital status, menopausal age, smoking, drinking, shift experience and shift years were collected. The relationship between shift work and menopausal age as well as menstruation span of professional women were analyzed by multivariate linear regression model. Results: There were 359 people (10.2%) in the shift experience group, the menopausal age was (49.71±3.63) years, and the menstrual period was (34.27±3.92) years. The non-shift experience group were 3159 people (89.8%) , the menopausal age was (50.20±3.60) years, and the menstrual period was (34.86±4.13) years. The differences of menopausal age and menstrual years between the two groups were statistically significant (P<0.05) . After adjusting for factors such as passive smoking and drinking, the results of the multiple linear regression model showed that menopausal age, menstrual years were negatively correlated with shift work (ß=-0.493, -0.575, P<0.05) . Conclusion: Shifts are related to women's menopausal age and menstrual years, and attention should be paid to the impact of work intensity and circadian rhythm on the occupational health of female employees.

[A non-targeted metabolomics study on urine of occupational exposure people with titanium dioxide nanoparticles].

Objective: To investigate the effects of titanium dioxide nanoparticles (TiO(2) NPs) on urine metabolites in occupationally exposure people based on metabolomics technology, and to explore the mechanism of early health effects of TiO(2) NPs on occupational exposure. Methods: In October 2019, the TiO(2) NPs occupational exposure population was selected as the research object, of which 64 people were in the exposure group who had been engaged in TiO(2) NPs exposure positions for more than 1 year; the control group was 62 people, who were logistics administrative staff of the same company. The urine of the research subjects before class was collected, using the ultra-high performance liquid chromatography time-of-flight mass spectrometer to collect the metabolism data of the urine, Progenesis QI software for data preprocessing and metabolite identification, SIMCA-P software for the principal component analysis of the data and potential biomarkers screening, MetaboAnalyst 4.0 software for metabolic pathway enrichment analysis. Results: The urine metabolism profile of workers in the exposure group was different from the control group, and 44 potential biomarkers were screened and identified. These potential biomarkers were significantly enriched in three pathways (P<0.05) , namely D-arginine and D-ornithine metabolism pathway, nitrogen metabolism pathway and D-glutamine and D-glutamate metabolism pathways. Conclusion: The occupational exposure of TiO(2) NPs can affect the concentration of metabolites in people urine and metabolic pathways, which provides a direction for the study of occupational hazard mechanisms of TiO(2) NPs and the monitoring of health risks.

[Metabolomics study of urine with Benzene, Toluene and Xylene combined exposure based on ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry].

Objective: To study the effects of combined occupational exposure of benzene, toluene, and xylene on human metabolism at an overall level, and to screen biomarkers related to the combined occupational exposure of benzene, toluene, and xylene, and to explore the mechanism of early health effects preliminarily caused by combined occupational exposure of benzene, toluene, and xylene by identification of biomarkers and retrieval of metabolic pathways. Methods: A shoe-making company was selected as the research site. Twenty subjects for the exposed group and the control group were selected separately, and urine of the subjects was collected. The metabolic profiles of the samples were collected by liquid chromatography time-of-flight mass spectrometry, and professional metabolomics and multivariate statistical analysis software were used to establish PCA and OPLS-DA analysis models to screen potential biomarkers and identify biomarkers. Finally, based on the dynamic changes and trends of potential biomarkers between groups, the mechanism of body damage caused by benzene, toluene, and xylene was initially explored. Results: Urine metabolomics analysis showed that the metabolic profile of urine samples of the benzene, toluene, and xylene combined exposure group was different from that of the control group. 27 potential biomarkers that were closely related to the combined exposure of benzene, toluene, and xylene were screened and identified. These potential biomarkers were enriched in 16 metabolic pathways, of which 3 pathways were significantly enriched (P<0.05) , respectively, lysine metabolism, amino sugar metabolism, and nucleotide sugar metabolism. Conclusion: The metabonomics method can well reflect the changes in the metabolome of urine samples in the occupational population after the combined exposure of benzene, toluene, and xylene, which will help us better evaluate the risk of combined exposure of benzene, toluene, and xylene and prevent and control their health risks.

Facile fabrication of hydrophobic cellulose-based organic/inorganic nanomaterial modified with POSS by plasma treatment.

A novel hydrophobic cellulose-based organic/inorganic nanomaterial (cellulose/TS-POSS) was prepared by oxygen plasma treatment followed by condensation reaction with TriSilanollsobutyl-Polyhedral oligomeric silsesquioxane. By careful design of cellulose film modified with TS-POSS by plasma etching, not only simply activated the hydroxyl groups on fiber surface, but also lowered the surface energy and increased the surface roughness. The surface morphology, chemical structure, thermal properties, and hydrophobic properties of cellulose/TS-POSS materials were systematically investigated by FTIR, SEM, AFM, CA, and TGA, respectively. The experimental results showed that the static water contact angle of cellulose/TS-POSS was 152.9°, demonstrating super-hydrophobicity. The results indicated that the TS-POSS were observed uniformly dispersed in the cellulose at the nanometer scale to form nanostructures, successful bonding to cellulose through condensation reaction. This process developed in this paper provided new solutions and approximations for the facile fabrication of sustainable cellulose-based hydrophobic materials.

[HIV infection and associated factors of male sex workers among men who have sex with men].

Objective: This study aimed to discover the HIV infection and associated factors among male sex workers (MSW) who provide sexual services for men. Data from this study thus can be used to provide evidence for designing related intervention programs. Methods: In this observational study, MSW were recruited from May to July, 2019 in KTV venues in Wuxi, China. A questionnaire was used to collect information with blood sample collected and tested for HIV and syphilis. EpiData 3.0 and SPSS 17.0 software were used to clean up data and statistical analysis. Results: A number of 500 MSW were involved including 243 (48.6%) heterosexual and 257 (51.4%) homosexual MSW. The overall HIV prevalence was 5.4%(27/500) among all the MSW. there were significant differences between the HIV prevalence rates, the heterosexual MSW (3.3%, 8/243) and the homosexual MSW (7.4%, 19/257)(χ(2)=4.112, P=0.043). In the past 3 months, 28.0% (72/257) of the homosexual MSW mainly engaged in receptive anal sex which was higher than 11.5%(28/243) of the heterosexual MSW. Compared to 15.6% (40/257) of the homosexual MSW who engaged in heterosexual behavior, a higher proportion of 98.4% (239/243) was noticed among the heterosexual MSW. Higher percentage (44.9%, 109/243) appeared among the heterosexual MSW who had not been tested for HIV than the homosexual MSW (20.6%, 53/257). Results from logistic regression multivariate analysis showed that age ≥30 (aOR=7.54, 95%CI: 2.53-37.11), having unprotected anal sexual practice (aOR=3.76, 95%CI:1.15-12.23), having anal sex after drinking alcohol (aOR=10.91, 95%CI: 2.29-51.87) and syphilis tested positive (aOR=8.23, 95%CI:1.29-52.51) were risk factors associated with HIV infection among the heterosexual MSW. Having unprotected anal sexual behavior (aOR=2.94, 95%CI: 1.17-7.37), having group anal sex (aOR=4.08, 95%CI:1.05-15.81), without record on HIV testing (aOR=6.58, 95%CI: 2.01-18.06) and syphilis tested positive (aOR=4.55, 95%CI: 1.15-18.06) were risk factors associated with HIV among the homosexual MSW. Conclusions: High HIV prevalence was discovered among both heterosexual and homosexual MSW in Wuxi, China. Differences in sexual behaviors between these two groups should be considered when designing targeted HIV intervention programs for these populations.

Downregulation of lncRNA CCHE1 inhibits cell proliferation, migration and invasion by suppressing MEK/ERK/c-MYC pathway in nasopharyngeal carcinoma.

OBJECTIVE: The current study was designed to investigate the functionality of lncRNA CCHE1 in nasopharyngeal carcinoma. MATERIALS AND METHODS: MiRNA levels of lncRNA CCHE1 were examined by RT-qPCR. CCK8 assay and colony formation assay were together performed to detect cell proliferation viability. Furthermore, wound healing assay and transwell assay were respectively conducted to assess cell migration and invasion. In addition, proteins related to MEK/ERK/c-MYC pathway were detected by Western blot. RESULTS: Elevated levels of CCHE1 were verified in NPC cell lines. Downregulation of CCHE1 significantly inhibited tumor growth and suppressed A549 cell proliferation, migration and invasion. MEK/ERK/c-MYC pathway was activated in nasopharyngeal carcinoma. Treatment of PD98059 (MEK inhibitor) or SCH772984 (ERK inhibitor) reversed the effects of CCHE1 on cell proliferation, migration and invasion in NPC. CONCLUSIONS: The present study suggested that downregulation of lncRNA CCHE1 could inhibit cell proliferation, migration and invasion by suppressing MEK/ERK/c-MYC pathway in nasopharyngeal carcinoma.

Hepatitis B core antigen-based vaccine demonstrates cross-neutralization against heterologous North American Porcine Reproductive and Respiratory Syndrome Virus (PRRSV-2) strains.

The U.S. swine industry have been bearing the financial impact of Porcine Reproductive and Respiratory Syndrome (PRRS) for decades. Absent of a safe and efficacious vaccine to combat PRRS virus's genetic heterogeneity, it remains a costly disease on pig farms across the country. We have developed virus-like-particle (VLP) based vaccines that incorporate 4 PRRSV epitopes in the hepatitis B core antigen (HBcAg) backbone. Administration of the vaccines in female BALB/C mice resulted in extremely significant PRRSV epitope specific antibody response. One vaccine candidate GP3-4 was able to mount a significant viral neutralizing response against both parental PRRSV strain VR2385 and heterologous PRRSV strain NADC20, showing a promising potential for cross-protection against PRRSV.

[The application of amodified scalp retractor in the craniotomy for intracranial aneurysms].

Objective: To investigate the application of a modified scalp retractor in the craniotomy for intracranial aneurysms withlateral supraorbital approach. Methods: From January 2019 to April 2020, a total of 32 patients with anterior circulation aneurysms clipping by superior lateral orbital approach were selected from Beijing Tiantan Hospital and Peking University International Hospital. The subjects were randomly divided into the traditional scalp retractor group and the modified scalp retractor group utilizing a random number table, with 16 patients in each group. The number of intraoperative retractor adjustment, incision length, postoperative scalp necrosis rate, postoperative wound healing grade, postoperative neurosurgical satisfaction score and patients' satisfaction score for incision were compared between the two groups. Results: The number of retractor adjustment in the modified scalp retractors group was significantly less than that in the traditional scalp retractor group (10.1±2.2 vs 14.2±3.6, P<0.05) . Incision length was also significantly shorter than that of the conventional scalp retractor group ( (10.1±1.0) cm vs (13.9±0.9) cm, P<0.05) .Neurosurgeons were significantly more satisfied with modified scalp retractors than the traditional scalp retractors (8.1±0.9 vs 6.0±0.9, P<0.05). There was no significant difference in postoperative scalp necrosis rate between two groups (P>0.05). Conclusion: The modified scalp retractor group is superior to the traditional scalp retractor group in the craniotomy for intracranial aneurysms with later supraorbital approach, with shorter in cision, less retractor adjustment and shorter surgical time.

[Study on HIV testing behavior among men who have sex with men based on structural equation model].

Objective: To analyze HIV testing behaviors and associated factors in men who have sex with men (MSM) and provide evidence for making intervention on promoting HIV testing. Methods: Our observational study was conducted between April and June, 2018 in Wuxi, Jiangsu province in MSM. A self-completed questionnaire was used to collect the information about their socio-demographic characteristics, sexual behaviors, acceptance of intervention services, psychological status and HIV testing behaviors. Structural equation model (SEM) was chosen to fit data and the model was modified to analyze the relationships between variables. Results: A total of 410 MSM were enrolled in our study, among whom 72.9%(299/410) were aware of the necessity of HIV testing and 69.0%(283/410) reported having HIV tests in the last year. A modified structural equation model presented good fitting results with fitting index of root mean square error of approximation (RMSEA)was 0.065, normed fit index (NFI) was 0.946, relative fit index (RFI) was 0.922, Tucker-Lewis index (TLI) was 0.968 and comparative fit index (CFI) was 0.952. Results of SEM showed that intervention service was the factor with the largest standardized total effect value of 0.57 associated with HIV testing behaviors among MSM. Among intervention services, HIV testing reminding had the biggest factor loading of 0.88. Psychological status scores played a negative role in HIV testing behaviors among MSM with the path coefficient value of -0.33. Conclusions: The awareness and testing rate of HIV among MSM population need to be further improved. While effective measures are implemented to promote HIV testing among MSM, more attention should be paid to the mental health problems of MSM.

[Study on synthetic drug use and associated factors among men who have sex with men at high risk of HIV infection].

Objective: To understand the current status of synthetic drug use and associated factors among men who have sex with men (MSM) at high risk of HIV infection. Methods: A cross- sectional study was conducted in Guangzhou, Wuxi and Shenzhen through January to August 2017. MSM at high risk of HIV infection were recruited from attendants at the health clinics, through internet advertisement and snowball sampling method. Eligible MSM were the ones who had met the following criteria: ≥18 years old, having either 2 male sex partners, or condomless anal sex with a casual male sex partner, or a STD historg during the past 6 months. Data regarding demographic, sexual behavior, HIV/STD testing history and previous drug use were collected by sely-administered questionnaires. Blood was also drawn for HIV testing. Results: Of the 603 MSM at high risk of HIV, 25.5% (154/603, 95%CI: 22.0%-29.0%) of them had used drugs in the past 6 months, including 29.1% (88/302, 95%CI: 24.0%-34.3%) in Guangzhou, 26.3% (40/152, 95%CI: 19.2%-33.4%) in Shenzhen, and 17.4% (26/149, 95%CI: 11.3%-23.6%) in Wuxi. 'Rush' (85.1%, 131/154) was the most commonly used drug. Results from the multivariable logistic regression revealed that drug use was associated with the following factors: having multiple casual sexual partners (aOR=3.24, 95%CI: 1.29-7.43) and alcohol use (aOR=1.78, 95%CI: 1.12-2.80) in the past 6 months after adjusting for age, education and monthly income. Conclusions: Drug use seemed common among MSM population at high risk of HIV infection and was associated with higher risk behavior that leading to HIV infection. Synthetic drug use among MSM deserved more attention.

[Determination of seven urinary metabolites of benzene, toluene and xylene by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry].

Objective: To develop a method using ultra-high performance liquid chromatography-triple quadrupole mass spectrometry to determine the urinary metabolites of benzene, toluene and xylene. The selected metabolites are S-phenylmercapturic acid (S-PMA) , trans, trans-muconic acid (t, t-MA) , 8-hydroxy-2 deoxyguanosine (8-OHdG) , hippuric acid (HA) , 2-methylhippuric acid (2-MHA) , 3-methylhippuric acid (3-MHA) and 4-methylhippuric acid (4-MHA) . Methods: The urine sample was pretreated using methanol to precipitate the proteins. HSS T3 chromatographic column was used to separate the metabolites. The mass spectrometric acquisition was carried out using multiple reaction monitoring (MRM) after ionization with ESI source. External standard method was used for quantification. Results: All the standard curves showed good linear relation, and r of the seven metabolites was all above 0.999. The detection limits and quantitative limits of the seven metabolites were 0.01-500 ng/ml and 0.02-1 000 ng/ml (based on the actual dilution ratio) , respectively. The average spiked recoveries of four loadings ranged from 85.8% to 109.9%. The intra-day and inter-day precisions were 0.2%-4.5% and 0.6%-9.5%, respectively. The samples can be kept for at least 14 days at both 4 ℃ and -20 ℃. Conclusion: This method is simple, rapid and highly sensitive with low cost, and its accuracy, precision and stability can meet the daily test requirements. It can be applied for the determination of urinary S-PMA, t, t-MA, 8-OHdG, HA, 2-MHA, 3-MHA and 4-MHA for the occupational population exposed to benzene, toluene and xylene.

[Determination of Cortisol in Saliva by Liquid Chromatography Tandem Mass Spectrometry].

Objective: To establish a liquid chromatography tandem mass spectrometry method to determine the cortisol in saliva. Methods: Take 0.5 ml saliva sample into a 2 ml centrifuge tube, add excess sodium chloride and 1ml acetonitrile to it, then vortex for 3 min, centrifuge for 10 min at 15 000 r/min, and take 800 µl of the upper layer to another centrifuge tube. Finally, the sample was concentrated by a vacuum concentrator and brought to 200 µl with the initial mobile phase. Then, the sample was analyzed by liquid chromatography tandem mass spectrometry. The target compound was quantified by external standard curve method. Results: The linear range of the method was 0.02-5.00 ng/ml, r=0.999 9, the method limit of the detection was 0.002 ng/ml, the method limit of quantitative was 0.02 ng/ml, and the spiked recoveries were 89.60%-98.60%. The intra-assay precision was 1.90%-3.30%, and the inter-assay precision was 4.20%-9.00%; samples could be stored at -20 °C for at least 14 days. The determination of cortisol could not be interfered by other endogenous substances in the sample. Conclusion: The method is simple in pretreatment, high sensitivity, good reproducibility and good recovery, and it is suitable for the quantitative analysis of cortisol in saliva for normal and occupationally stressed populations.

HGF alleviates renal interstitial fibrosis via inhibiting the TGF-ß1/SMAD pathway.

OBJECTIVE: To study the role of HGF (stem cell growth factor) in renal interstitial fibrosis and to explore its underlying mechanism. MATERIALS AND METHODS: A unilateral ureteral obstruction (UUO) mouse model was first constructed, and kidney samples of mice were then collected. Fibrosis-related indicators in UUO mice kidney were detected by Western blot. The mRNA and protein levels of HGF in UUO mice were detected by quantitative Real-time-polymerase chain reaction (qRT-PCR) and Western blot, respectively. The HGF overexpression mouse model was established by using UUO mice. For in vitro experiments, fibrosis-related indicators and the expression of HGF were detected in transforming growth factor-ß1 (TGF-ß1)-induced NRK-52E cells. Finally, a p-SMAD3 knockdown mouse model was established to confirm whether p-SMAD3 was involved in HGF-regulated renal interstitial fibrosis. RESULTS: The expression levels of HGF and α-SMA (α-smooth muscle actin) were both significantly increased in UUO mice, while E-cadherin expression was significantly decreased, which were consistent with results of in vitro experiments. Overexpression of HGF remarkably decreased the protein and mRNA levels of α-SMA in fibrotic NRK-52E cells. After overexpression of HGF in UUO mice, α-SMA was remarkably downregulated, whereas E-cadherin was significantly upregulated. Further, results also demonstrated that HGF was upregulated and α-SMA was downregulated after p-SMAD3 knockdown in UUO mice. CONCLUSIONS: HGF is highly expressed during renal interstitial fibrosis, which may suppress renal interstitial fibrosis by inhibiting the TGF-ß1/SMAD signaling pathway.