[Application of mixture analysis methods in association between metals mixture exposure and DNA oxidative damage].

Objectives: To study the association between metals mixture exposure and DNA oxidative damage using mixture analysis methods, and to explore the most significant exposure factors that cause DNA oxidative damage. Methods: Workers from steel enterprises were recruited in Shandong Province. Urinary metals were measured by using the inductively coupled plasma mass spectrometry method. The level of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was determined by using the ultra-high performance liquid chromatography-mass spectrometry method. Bayesian kernel machine regression (BKMR), elastic net regression and quantile g-computation regression were used to analyze the association between urinary metals and urinary 8-OHdG. Results: A total of 768 subjects aged (36.15±7.40) years old were included in the study. BKMR, elastic net regression and quantile g-computation all revealed an overall positive association between the mixture concentration and increased urinary 8-OHdG. The quantile g-computation results showed that with a 25% increase in metal mixtures, the urinary 8-OHdG level increased by 77.60%. The elastic net regression showed that with a 25% increase in exposure risk score, the urinary 8-OHdG level increased by 26%. The BKMR summarized the contribution of individual exposures to the response, and selenium, zinc, and nickel were significant contributors to the urinary 8-OHdG elevation. Conclusion: Exposure to mixed metals causes elevated levels of DNA oxidative damage, and selenium, zinc, and nickel are significant exposure factors.

Postoperative pulmonary complications in older patients undergoing elective surgery with a supraglottic airway device or tracheal intubation.

The two most commonly used airway management techniques during general anaesthesia are supraglottic airway devices and tracheal tubes. In older patients undergoing elective non-cardiothoracic surgery under general anaesthesia with positive pressure ventilation, we hypothesised that a composite measure of in-hospital postoperative pulmonary complications would be less frequent when a supraglottic airway device was used compared with a tracheal tube. We studied patients aged ≥ 70 years in 17 clinical centres. Patients were allocated randomly to airway management with a supraglottic airway device or a tracheal tube. Between August 2016 and April 2020, 2900 patients were studied, of whom 2751 were included in the primary analysis (1387 with supraglottic airway device and 1364 with a tracheal tube). Pre-operatively, 2431 (88.4%) patients were estimated to have a postoperative pulmonary complication risk index of 1-2. Postoperative pulmonary complications, mostly coughing, occurred in 270 of 1387 patients (19.5%) allocated to a supraglottic airway device and 342 of 1364 patients (25.1%) assigned to a tracheal tube (absolute difference -5.6% (95%CI -8.7 to -2.5), risk ratio 0.78 (95%CI 0.67-0.89); p < 0.001). Among otherwise healthy older patients undergoing elective surgery under general anaesthesia with intra-operative positive pressure ventilation of their lungs, there were fewer postoperative pulmonary complications when the airway was managed with a supraglottic airway device compared with a tracheal tube.

[Dose-effect relationship between serum polycyclic aromatic hydrocarbon adducts and serum complements among children in a city of East China].

Objective: To investigate the dose-response relationship between serum polycyclic aromatic hydrocarbon adducts and serum complement C3 and C4 levels among children from a city in East China. Methods: In September 2016, two boarding schools in the air pollution exposure area and the control area (beyond the upwind of 30 km in the air pollution exposure area) in a city in East China were selected as the research site, and the eligible school-age children were recruited as the research objects. A total of 273 children were included, including 163 in the exposure group and 110 in the control group. The annual air pollutant data (PM2.5, PM10 and NO2) of the two regions during the study period were collected. The exposure level of tobacco was evaluated by cotinine in urine. The levels of serum complement C3 and C4 were determined by automatic biochemical analyzer. The serum anti-7, 8, -dihydrodiol-9, 10-epoxide benzo[a]pyrene (BPDE)-albumin adduct levels were detected by ELISA. Linear regression model was used to explore the dose-response relationship between BPDE-albumin adducts and serum complement C3 and C4. Results: The age of 273 subjects was (13.67±0.37) years old, including 165 boys (60.4%). The average annual exposure levels of PM2.5, PM10 and NO2 and the level of serum BPDE-albumin adducts in the exposure group were higher than those in the control group (P<0.05). The results of linear regression model analysis showed that after adjusting age, sex, BMI z-score and urinary cotinine level, when the serum BPDE-albumin adduct level increased by 10%, the serum complement C4 level decreased by 1.2% (P=0.017). After adjusting age, BMI z-score and urinary cotinine level, for every 10% increase in serum BPDE-albumin adduct level in boys, the serum complement C4 level decreased by 1.68% (P=0.024). After adjusting age, sex and BMI z-score, the levels of serum complement C3 and C4 decreased by 1.31% and 3.57% respectively for every 10% increase in serum BPDE-albumin adducts among children in the urinary cotinine detection group (P<0.05). Conclusion: There is a significant dose-response relationship between serum BPDE-albumin adducts and the complement C4 among children.

[Analysis of the relationship between the changes of lung function and serum proinflammatory cytokines in workers occupationally exposed to toluene diisocyanate].

Objective: To analyze the correlation between the changes of lung function and serum proinflammatory cytokines in workers occupationally exposed to toluene diisocyanate (TDI), and to explore the evaluation index of respiratory toxicity of TDI. Methods: In October 2014, 61 male workers engaged in TDI synthesis process, purification process, packaging process and the above production process in a TDI factory in western China were selected as TDI exposure group; 62 male enterprise managers who were not exposed to TDI and other known allergenic chemicals were selected as control group, which were matched at the age of workers in exposure group. The questionnaire survey obtained information such as gender, length of service, age, occupational history, exposed length of service and so on. The lung function indexes [forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC] and serum levels of interleukin (IL)-1 ß, IL-6, IL-8, tumor necrosis factor (TNF)-α, macrophage inflammatory factor-1 ß, monocyte chemoattractant factor-1 and vascular endothelial growth factor were measured. The urine was collected after the weekend shift, and the concentration of (TDA), the metabolite of TDI, was determined as the index of internal exposure. Spearman rank correlation was used to analyze the correlation between cytokines and lung function indexes, and multivariate linear regression was used to analyze the changes of lung function indexes and cytokines with TDI exposure concentration and time. Results: The median age (P5-P95) of the exposed group and the control group was 36.5 (24.0-51.0) and 38.0 (24.0-50.0) years, respectively. In the exposed group, the median length of service (P5-P95) was 6.94 (0.97-26.33) years, and the median concentration of TDA in urine was 15.56 (2.28-112.16) ng/ml. The three indexes of lung function, FVC, FEV1, FEV1/FVC and the levels of serum IL-8 and TNF-α were significantly lower than those in the control group (P<0.01). With the increase of exposure concentration and exposure time, the level of serum TNF-α, FVC and FEV1 decreased, and showed a good dose-effect and time-effect relationship (all Ptrend values< 0.05). Serum IL-8 and TNF-α were positively correlated with FVC, FEV1 and FEV1/FVC (all P values<0.01). Conclusion: The levels of serum inflammatory factors IL-8 and TNF-α in worker exposed to TDI are related to lung function indexes, which can be used as early evaluation indexes of respiratory toxicity induced by TDI.

[Risk-factor analysis of poor graft function after allogeneic hematopoietic stem cell transplantation for severe aplastic anemia].

Objective: To investigate the risk factors of poor graft function (PGF) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for severe aplastic anemia (SAA) . Methods: Clinical data from 111 SAA patients who received allo-HSCT were analyzed retrospectively. Factors including age, gender, interval to transplantation, the level of serum ferritin before transplantation were analyzed by Cox multivariate regression analysis. Results: Among the 111 patients who underwent allo-HSCT, 16 developed PGF (14.4%) . Multivariate analysis showed donor type (HR=2.656, 95%CI 1.204-5.858, P= 0.016) and the level of serum ferritin before tansplantation (HR=3.170, 95%CI 1.400-7.180, P=0.006) were significant risk factors for PGF. Conclusion: Unrelated donor transplantation and the high level of serum ferritin before transplantation are risk factors for PGF.

[Association of etheno-DNA adduct and DNA methylation level among workers exposed to diesel engine exhaust].

Objective: To investigate the association between etheno-DNA adduct and the promoter of DNA methylation levels of cyclin dependent kinase inhibitor 2A (P16), Ras association domain family 1 (RASSF1A) and O-6-methylguanine-DNA methyltransferase (MGMT) in workers with occupational exposure to diesel engine exhaust (DEE). Methods: We recruited 124 diesel engine testing workers as DEE exposure group and 112 water pump operator in the same area as control group in Henan province in 2012 using cluster sampling. The demographic data were obtained by questionnaire survey; urine after work and venous blood samples were collected from each subject. The urinary etheno-DNA adducts were detected using UPLC-MS/MS, including 1,N6-etheno-2'-deoxyadenosine (εdA) and 3,N4-etheno-2'-deoxycytidine(εdC). The DNA methylation levels of P16, RASSF1A, and MGMT were evaluated using bisulfite-pyrosequencing assay. The percentage of methylation was expressed as the 5-methylcytosine (5mC) over the sum of cytosines (%5mC). Spearman correlation and multiple linear regression were applied to analyze the association between etheno-DNA adducts and DNA methylation of P16, RASSF1A, and MGMT. Results: The median (P(25)-P(75)) of urinary εdA level was 230.00 (98.04-470.91) pmol/g creatinine in DEE exposure group, and 102.10 (49.95-194.48) creatinine in control group. The level of εdA was higher in DEE exposure group than control group (P<0.001). DNA methylation levels of P16, RASSF1A and MGMT were 2.04±0.41, 2.19 (1.94-2.51), 2.22 (1.94-2.46)%5mC in exposure group, and 2.19±0.40, 2.41 (2.11-2.67), 2.44 (2.15-2.91)%5mC in control group. DNA methylation levels were lower in exposure group (P values were 0.005, 0.002 and 0.001, respectively). Spearman correlation analysis showed that DNA methylation levels of P16, RASSF1A, and MGMT were negative associated with urinary εdA level (r values were -0.155, -0.137, and -0.198, respectively, P<0.05). No significant correlation was observed between the εdC level and any measured DNA methylation levels (P>0.05) . Multiple linear regression confirmed the negative correlation between εdA and DNA methylation levels of P16, RASSF1A, and MGMT in non-smoking group (ß (95%CI) was -0.068 (-0.132--0.003), -0.082 (-0.159--0.004) and -0.048 (-0.090--0.007), P values were 0.039, 0.039 and 0.024, respectively). Moreover, εdC was negative associated with DNA methylation level of MGMT in non-smoking group (ß (95%CI) was -0.094 (-0.179--0.008), P=0.032). Conclusion: DEE exposure could induce the increased of εdA and decreased of DNA methylation levels of P16, RASSF1A and MGMT.

[Analysis on the nuclear division index of peripheral blood lymphocytes in the 281 general population of Anhui, China].

OBJECTIVE: To investigate the reference range and influeing factors of the nuclear division index (NDI) of peripheral blood lymphocyte in Chinese general population in Anhui province. METHODS: We selected 281 subjects from the general poulation in Anhui province, without occupational exposure to genetic toxicants and no chronic disease history. We used questionnaires to collect occupational history, age, gender, region, body mass index, smoking, and alcohol drinking status etc. NDI was measured by cytokinesis block micronucleus assay in peripheral blood lymphocytes, and the related factors were also analyzed. And NDI was used as the dependent variable, age, gender and other factors as independent variables to conduct stepwise multiple linear regression. RESULTS: We found the data of NDI according with normal distribution, and the nuclear division index was 1.71±0.22, the minimum value was 1.10 while the maximum was 2.36. The results showed that NDI value of the males (1.67±0.20) were lower than that of the females (1.76±0.24), the difference was statistically significant (t=-3.65, P<0.001); current smokers NDI (1.66±0.18) lower than non-smokers (1.73±0.24) differences were statistically significant (t=3.06, P=0.002); the NDI of drinking groups (1.66±0.20) was lower than that of non-drinking population (1.74±0.23), the differences was statistically significant (t=3.15, P=0.002); Using multiple stepwise linear regression calibration factors and found that gender was an independent factor of NDI (ß=0.098, Sx=0.027, t=3.66, P< 0.001). CONCLUSION: We set the reference value on the nuclear division index among general population of survey areas in this study, it could provide a reference for similar studies and will provide reference for better evaluation of the effects of hazards on the body.

[Analysis of 8-hydroxy-2'-deoxyguanosine in human urine by ultra-high performance liquid chromatography mass spectrometer method].

OBJECTIVE: To develop an ultra-high performance liquid chromatography mass spectrometer method for the rapid determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in human urines. METHODS: 8-OHdG standard solution with the concentration from 0.01 to 0.1 µg/ml was formulated. The solution was implanted into ion source with a rate of 7 µl/min, the mass-to-charge ratio of parent ion and product ions, and ion mass to charge ratio was identified. The mass spectrum parameters of each Ion pairs, such as DP, EP and EXP, were gradually optimized. The urine sample with a concentration of 10.0 µg/L was detected, and the pH of the sample was adjusted using 1 mol/L ammonium formate and formic acid solution with a volume ratio of 5∶1, 4∶1, 3∶1, 2∶1, and 1∶1. It was tested using three different polarity of SPE, i.e.: HLB, MCX, and MAX. The elution effect of methanol and water mixture with the proportion of 90∶10, 80∶20, 50: 50, 20: 80, and 10: 90 were tested, and then acetonitrile and water mixture with the proportion of 90∶10, 80∶20, 50∶50, 20∶80, 10∶90 were also tested. The standard curve was constructed using the ratio of a standard series application fluid concentration to corresponding compounds quantitative ion liquid concentration of the peak area. The detection limit was determined as 3 times of the signal to noise ratio corresponding to the concentration of 8-OHdG, and the quantitative lower limit was determined as 10 times of the signal to noise ratio corresponding to the concentration of 8-OHdG. The blank urine spiked recovery method was used to evaluate the precision and recovery rate. RESULTS: The mass to charge ratio of parent ion was 284.1 and the product ions was 168.1, 140.1, 123.0, and 112.0, respectively. The collision voltage of quantitative ion-pair 284.1/168.1 was 18 V, the 284.1/140.1 collision voltage was 42 V, the 284.1/123.0 collision voltage was 48 V, and the 284.1/112.0 collision voltage was 53 V. The recovery rate was the highest (87.9%-104.3%) when the pH of urine was adjusted by a 10 ml 1 mol/L ammonium formate solution, 2 ml of formic acid, 88 ml of water are mixed with the sample solution volume ratio of 1∶5, and then purified with 3 ml of methanol and 3 ml water activated HLB extraction column. Within 1.0-100.0 µg/L concentration range, 8-OHdG standard application solution test results showed a good linear relationship. The regression equation was y= 1.25x+0.74, and the correlation coefficient was r=0.999 5. The detection limit was 0.2 µg/L, and the limit of quantification was 0.7 µg/L. The method of recovery rate was in the range of 87.9% to 104.3%, the precision was in the range from 1.5% to 3.7% and inter-assay precision was in the range from 1.6% to 5.4%. CONCLUSION: The method developed in this study had high sensitivity, good precision and accuracy, and a wide range of testing concentrations.

[Effect of high density lipoprotein (HDL) on the clearance of intracellular lipids with special reference to the co-effect of nifedipine].

More than 90% of peritoneal macrophages collected from the diet-induced hyperlipidemic rabbits were noticed to be loaded with abundant lipids, and were morphologically similar to the foamy cells infiltrating in the atheromatous lesion. Data of this experiment showed that HDL could promote the clearance rate of intracellular cholesterol efflux and this effect could be strengthened in the progress of time that HDL could transport more than 30% of the accumulated lipids from the cultured cells in 96 hours. Data also indicated that nifedipine was able to promote the hydrolysis of cholesteryl esters in the cultured cells. Addition of nifedipine to the culture media originally containing only HDL promoted the ability of foamy cells in excreting intracellular cholesterol via a hitherto unknown mechanism. This study indicated that nifedipine enhanced the cholesterol efflux mediated by HDL.