Objective To evaluate the application of three deep learning algorithms in automatic segmentation of clinical target volumes (CTVs) in high-dose-rate brachytherapy after surgery for endometrial carcinoma. Methods A dataset comprising computed tomography scans from 306 post-surgery patients with endometrial carcinoma was divided into three subsets: 246 cases for training, 30 cases for validation, and 30 cases for testing. Three deep convolutional neural network models, 3D U-Net, 3D Res U-Net, and V-Net, were compared for CTV segmentation. Several commonly used quantitative metrics were employed, i.e., Dice similarity coefficient, Hausdorff distance, 95th percentile of Hausdorff distance, and Intersection over Union. Results During the testing phase, CTV segmentation with 3D U-Net, 3D Res U-Net, and V-Net showed a mean Dice similarity coefficient of 0.90 ± 0.07, 0.95 ± 0.06, and 0.95 ± 0.06, a mean Hausdorff distance of 2.51 ± 1.70, 0.96 ± 1.01, and 0.98 ± 0.95 mm, a mean 95th percentile of Hausdorff distance of 1.33 ± 1.02, 0.65 ± 0.91, and 0.40 ± 0.72 mm, and a mean Intersection over Union of 0.85 ± 0.11, 0.91 ± 0.09, and 0.92 ± 0.09, respectively. Segmentation based on V-Net was similarly to that performed by experienced radiation oncologists. The CTV segmentation time was < 3.2 s, which could save the work time of clinicians. Conclusion V-Net is better than other models in CTV segmentation as indicated by quantitative metrics and clinician assessment. Additionally, the method is highly consistent with the ground truth, reducing inter-doctor variability and treatment time.

Gaining a better understanding of autoprotection against drug-induced liver injury(DILI)may provide new strategies for its prevention and therapy.However,little is known about the underlying mechanisms of this phenomenon.We used single-cell RNA sequencing to characterize the dynamics and functions of hepatic non-parenchymal cells(NPCs)in autoprotection against DILI,using acetaminophen(APAP)as a model drug.Autoprotection was modeled through pretreatment with a mildly hepatotoxic dose of APAP in mice,followed by a higher dose in a secondary challenge.NPC subsets and dynamic changes were identified in the APAP(hepatotoxicity-sensitive)and APAP-resistant(hepatotoxicity-resistant)groups.A chemokine(C-C motif)ligand 2+endothelial cell subset almost disappeared in the APAP-resistant group,and an R-spondin 3+endothelial cell subset promoted hepatocyte proliferation and played an important role in APAP autoprotection.Moreover,the dendritic cell subset DC-3 may protect the liver from APAP hepatotoxicity by inducing low reactivity and suppressing the autoimmune response and occurrence of inflammation.DC-3 cells also promoted angiogenesis through crosstalk with endothelial cells via vascular endothelial growth factor-associated ligand-receptor pairs and facilitated liver tissue repair in the APAP-resistant group.In addition,the natural killer cell subsets NK-3 and NK-4 and the Sca-1-CD62L+natural killer T cell subset may promote autoprotection through interferon-y-dependent pathways.Furthermore,macrophage and neutrophil subpopulations with anti-inflammatory phenotypes promoted tolerance to APAP hepatotoxicity.Overall,this study reveals the dynamics of NPCs in the resistance to APAP hepatotoxicity and provides novel insights into the mechanism of autoprotection against DILI at a high resolution.

Objective:To study the patterns of tocilizumab (TCZ) use, its efficacy and safety in patients with rheumatoid arthritis (RA) in routine clinical practice.Methods:A total of 407 patients with RA were enrolled from 23 centers and treated with TCZ within 8 weeks prior to the enrollment visit, and were followed for 6-month. The patterns of TCZ treatment at 6 months, the effectiveness and safety outcomes were recorded. Statistical analysis was performed using SAS version 9.4.Results:A total of 396 patients were included for analysis, in which 330 (83.3%) patients received TCZ combined with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), and 16.7%(66/396) received TCZ monotherapy. At baseline, TCZ was initiated in 56.6%(224/396) and 9.6%(38/396) of patients after failure of DMARDs and other biological agents (bDMARDs) respectively. During the 6-month follow-up period, the mean frequency of TCZ administration was (3.7±1.6), the mean TCZ dosage was (7.4±1.2) mg/kg, and the mean interval between doses was (40±13) days. 120(25.8%) patients were on TCZ treatment at the end of the study. Improvements in disease activity, systemic symptoms and patient report outcomes were observed at the end of the study. 22.7%(90/396) patients experienced at least one treatment related adverse event, and 8 patients experienced at least one serious adverse event.Conclusion:This study demonstrates that TCZ treatment is effective in patients with RA when being treated for 6 months with an acceptable safety profile. The duration of TCZ treatment needs to be extended.

Objective:To investigate the changes of plasma high density lipoprotein cholesterol (HDL-C) and metabolic indicators in obese patients after laparoscopic sleeve gastrectomy (LSG).Methods:The retrospective cohort study was conducted. The clinical data of 69 obese patients who were admitted to the Tenth People′s Hospital of Tongji University from August 2013 to March 2017 were collected. There were 32 males and 37 females, aged (33±12)years, with a range from 18 to 65 years. Of 69 patients, 44 patients with preoperative HDL-C concentration <1.04 mmoL/L were allocated as low HDL-C group, and 25 patients with preoperative HDL-C concentration ≥1.04 mmoL/L were allocated as normal HDL-C group. Sixty-nine patients underwent LSG. Observation indicators: (1) analysis between preoperative HDL-C and clinical indicators; (2) follow-up; (3) stratified analysis of plasma HDL-C. Follow-up was conducted using outpatient examination and hospitalization review to detect changes of plasma HDL-C, insulin resistance index, uric acid, free fatty acids and body mass every 3 months after operation up to September 2017. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was analyzed using the t test. Measurement data with skewed distribution were represented as M ( P25, P75), and comparison between groups was analyzed using the Mann-Whitney U test. Count data were expressed as absolute numbers or percentages, and comparison between groups was analyzed using the chi-square test. Pearson correlation coefficient was used to analyze measurement data with normal distribution, and Spearman correlation was used to analyze measurement data with skewed distribution. Repeated measurement data were analyzed by ANOVA. Results:(1) Analysis between preoperative HDL-C and clinical indicators: results of correlation analysis showed that the preoperative plasma HDL-C concentration was negative correlated with the body mass, height, abdominal circumference, insulin resistance index and triglyceride in 69 patients ( r=-0.246, -0.307, -0.262, -0.253, -0.301, P<0.05), and the preoperative plasma HDL-C concentration was not correlated with the age, body mass index (BMI), fasting blood glucose, glycosylated hemoglobin, alanine aminotransferase, aspartate aminotransferase, gamma glutamyltransferase, uric acid, creatinine, free fatty acid, fasting serum insulin, total cholesterol and low density lipoprotein cholesterol ( P>0.05). The preoperative plasma HDL-C concentration was still negative correlated with the body mass in 69 patients after adjusting for age, BMI, fasting blood glucose, glycosylated hemoglobin, fasting serum insulin and insulin resistance index ( r=-0.277, P<0.05). (2) Follow-up: 69 patients were followed up postoperatively for 6 months (6 months, 12 months). The plasma HDL-C concentration, insulin resistance index, uric acid, free fatty acids, body mass of low HDL-C group at postoperative 3 and 6 months were (0.96±0.18)mmol/L, 2.20(0.51, 11.66), (411±93)μmol/L, 0.57 mmol/L (0.20 mmol/L, 1.00 mmol/L), (92±18)kg and (1.11±0.18)mmol/L, 2.19(0.71, 8.75), (389±100)μmol/L, 0.40 mmol/L(0.13 mmol/L, 1.10 mmol/L), (86±17)kg, respectively. The above indicators of normal HDL-C group at postoperative 3 and 6 months were (1.17±0.24)mmol/L, 2.22(0.24, 7.04), (379±105)μmol/L, 0.60 mmol/L(0.27 mmol/L, 1.10 mmol/L), (84±16)kg and (1.34±0.20)mmol/L, 1.60(0.36, 5.56), (359±92)μmol/L, 0.42 mmol/L (0.16 mmol/L, 2.90 mmol/L), (80±18)kg, respectively. There was significant difference in the changes of postoperative plasma HDL-C concentration between the two groups ( F=41.443, P<0.05), and there was interaction between groups and time points ( F=6.252, P<0.05). There was significant difference between different time points ( F=29.900, P<0.05). There was significant difference in the changes of postoperative insulin resistance index between the two groups ( F=4.313, P<0.05), and there was no interaction between groups and time points ( F=2.298, P>0.05). There was significant difference between different time points ( F=29.800, P<0.05). There was no significant difference in the changes of postoperative uric acid between the two groups ( F=1.669, P>0.05), and there was no interaction between groups and time points ( F=0.111, P>0.05). There was significant difference between different time points ( F=12.796, P<0.05). There was significant difference in the changes of postoperative free fatty acids between the two groups ( F=5.465, P<0.05), and there was no interaction between groups and time points ( F=0.504, P>0.05). There was no significant difference between different time points ( F=1.405, P>0.05). There was significant difference in the changes of postoperative body mass between the two groups ( F=5.614, P<0.05), and there was no interaction between groupsand time points ( F=2.174, P>0.05). There was significant difference between different time points ( F=497.496, P<0.05). (3) Stratified analysis of plasma HDL-C. ① Changes of postoperative plasma HDL-C in obese patients of different genders: of 69 patients, the plasma HDL-C concentration of the 32 male patients before operation and at postoperative 3 and 6 months were (0.91±0.19)mmol/L, (1.02±0.24)mmol/L, (1.18±0.23)mmol/L, respectively, and the percentage increase of plasma HDL-C concentration at postoperative 3 and 6 months were 12.00%(4.00%, 12.00%)and 20.00%(12.00%, 39.25%), respectively. The above indicators of the 37 female patients were (1.05±0.21)mmol/L, (1.06±0.22)mmol/L, (1.22±0.22)mmol/L and 0(-9.50%, 8.25%), 12.00%(2.00%, 23.00%), respectively. There was significant difference in the changes of percentage increase of plasma HDL-C concentration between the male and female patients ( F= 6.716, P<0.05), and there was interaction between groups and time points ( F=3.861, P<0.05). There was significant difference between different time points ( F=37.374, P<0.05). ② Changes of postoperative plasma HDL-C in obese patients of different genders in low HDL-C group and normal HDL-C group: of 44 patients in low HDL-C group, the plasma HDL-C concentration of the 24 male patients before operation and at postoperative 3 and 6 months were (0.82±0.12)mmol/L, (0.99±0.21)mmol/L, (1.12±0.22)mmol/L, respectively, and the percentage increase of plasma HDL-C concentration at postoperative 3 and 6 months were 16.00%(-1.75%, 28.75%) and 27.50%(15.75%, 43.50%), respectively. The above indicators of the 20 female patients in low HDL-C group were (0.89±0.08)mmol/L, (0.93±0.14)mmol/L, (1.10±0.14)mmol/L and 1.50%(-8.25%, 16.50%), 18.00%(9.00%, 23.00%), respectively. There was significant difference in the changes of percentage increase of plasma HDL-C concentration between the male and female patients ( F=4.503, P<0.05), and there was interaction between groups and time points ( F=3.594, P<0.05). There was significant difference between different time points ( F=37.096, P<0.05). Of 25 patients in normal HDL-C group, the plasma HDL-C concentration of the 8 male patients before operation and at postoperative 3 and 6 months were (1.15±0.12)mmol/L, (1.12±0.32)mmol/L, (1.32±0.21)mmol/L, respectively, and the percentage increase of plasma HDL-C concentration at postoperative 3 and 6 months were -1.00%(-14.00%, 12.00%), 13.50%(6.75%, 32.50%), respectively. The above indicators of the 17 female patients in normal HDL-C group were (1.23±0.16)mmol/L, (1.20±0.20)mmol/L, (1.36±0.20)mmol/L and 0(-13.75%, 4.25%), 5.50%(0, 28.50%), respectively. There was no significant difference in the changes of percentage increase of plasma HDL-C concentration between the male and female patients ( F=0.209, P>0.05), and there was no interaction between groups and time points ( F=0.176, P>0.05). There was significant difference between different time points ( F=6.481, P<0.05). Conclusions:For patients with low or normal plasma HDL-C concentration preoperative, there are significant differences in the changes of HDL-C, insulin resistance index, free fatty acids and body mass after LSG. There is significant difference in the changes of postoperative percentage increase of plasma HDL-C concentration between male and female patients who with low plasma HDL-C concentration preoperative.

Objective: To evaluate the safety and efficacy of foam sclerotherapy for bleeding internal hemorrhoids. Methods: Consecutive adult patients (aged 18-60 years) with bleeding hemorrhoids were prospectively enrolled between March 2017 and March 2018. All patients were randomly assigned to the foam sclerotherapy (FS) group and the liquid sclerotherapy (LS) group. The foam and liquid sclerotherapy of hemorrhoids nucleus was performed by cap-assisted colonic endoscopy. Results: A total of 108 patients were enrolled, including 62 males (57.4%) with mean age of 44.0±7.6 years. There was no significant difference in gender, age, or body mass index between the FS (n = 55) group and the LS (n =53) group. The total amount of lauromacrogol injection in the FS group was 3.7±0.9 mL, which was significantly lower than that in the LS group (8.0±2.2 mL, P<0.001). In the LS group, 8 patients (15.1%) developed bleeding after needle removal, which was significantly higher than that in the FS group [5.5%(3/53), P=0.022]. Significant pain was found in 2 patients (3.8%) in the LS group and 0 in the FS group (P= 0.025). The short-term cure rate and effective rate of the FS group were 87.3% (48/55) and 9.1% (5/55), while those were 69.8% (37/53) and 22.6% (12/53) in the LS group, respectively (P=0.046). Conclusion Foam sclerotherapy is safe and effective in the treatment of bleeding internal hemorrhoids.

OBJECTIVETo assess the effects of laparoscopic sleeve gastrectomy (LSG) on insulin secretion mode and metabolism of glucose and lipid in morbidly obese patients.

METHODSClinical data of 65 morbidly obese patients [body mass index (BMI) ≥30 kg/m] undergoing LSG at Shanghai 10th People's Hospital from August 2012 to December 2016 were retrospectively analyzed. According to the result of OGTT, these obese patients were divided into three groups: normal glucose tolerance (NGT, 23 cases), impaired glucose tolerance (IGT, 22 cases) and type 2 diabetes mellitus (DM, 20 cases) groups. Twenty-two healthy people [BMI (23.1±1.4) kg/m] were used as control group. The anthropometries parameters [weight, BMI, waist circumference, body fat percentage, excess weight loss(%EWL)], glucose metabolic indices [fasting plasma glucose (FPG), fasting insulin (FINS), glycosylated hemoglobin (HbA1c), homeostasis model assessment-insulin resistance index (HOMA-IR)], lipid profile (TC, TG, HDL-C, LDL-C) and inflammatory factor (UA, TNF-α) of 3 groups were detected before operation and at postoperative 1-, 3-, 6-month. These variables were analyzed among morbidly obese groups before and after surgery and compared to control group. Clinical registration number of this study was ChiCTROCSl2002381.

RESULTSBody weight, waist circumference and BMI of morbidly obese patients all decreased at postoperative 1-, 3-, 6-month. Postoperative %EWL increased obviously to (71.5±24.7)% with the highest range in DM group. Percentage of successful weight loss (%EWL>50%) in NGT, IGT and DM groups was 63.6%, 83.9% and 90.0% at postoperative 6-month respectively, and DM group was also the highest. At postoperative 6-month, HbA1c of 3 morbidly obese groups became normal; FPG and postprandial 2-hour glucose of IGT and DM group decreased to normal level; insulin level of 3 morbidly obese groups decreased obviously compared to pre-operation (all P<0.05), especially FINS and postprandial 2-hour insulin became normal without significant difference of control group (P>0.05), while postprandial 30-minute and 60-minute insulin levels in 3 groups were still higher as compared to control group. The insulin secretion curves of morbidly obese groups showed hyperinsulinemia before surgery. The peak of insulin secretion curve in IGT and DM group moved back to postprandial 120-minute before operation, and returned to 60-minute after operation, with basic normal rhythm of secretion curve. Preoperative HOMA-IR in all 3 morbidly obese groups was higher than that in control group (all P<0.05) and remarkably lower at postoperative 6-month compared to pre-operation(P<0.05). In 3 morbidly obese groups after operation, TG decreased, HDL-C increased, UA and TNF-α decreased significantly compared to before operation (all P<0.05). At postoperative 6-month, the HOMA-IR of DM group was positively correlated with BMI (r=0.236, P=0.004) and TNF-α (r=0.228, P=0.033), and was not correlated with HDL-C(P>0.05).

CONCLUSIONSLSG can effectively ameliorate hyperinsulinemia and insulin secretion curve, and improve metabolic disorder and insulin resistance of different stage in obesity patients with glucose metabolic disorder. Insulin resistance is correlated with body weight and inflammatory factors.

OBJECTIVETo investigate the effect of laparoscopic sleeve gastrectomy(LSG) on sex hormone in male patients with severe obesity.

METHODSRetrospective analysis was performed in 31 male patient with severe obese [body mass index(BMI) ≥28 kg/m, obesity group] who underwent LSG in Shanghai Tenth People's Hospital of Tongji University from December 2012 to May 2016. The anthropometric parameters(weight, BMI, waist circumference, hip circumference, waist-hip ratio, body fat percentage), glucose metabolic indices [fasting plasma glucose(FPG), fasting insulin (FINS), glycosylated hemoglobin (HbA1c), homeostasis model assessment-insulin resistance index(HOMA-IR)], and sex hormone parameters [estradiol(E2), total testosterone (TT), follicle-stimulating hormone (FSH) and luteinizing hormone (LH)] were collected preoperatively and 1, 3, 6 months postoperatively. In addition, 31 healthy male volunteers with normal BMI were consecutively recruited in this study as control group. The above-mentioned parameters were also determined in control group. Changes of these variables before and after surgery were analyzed. Pearson method was used to analyze the correlation of TT with anthropometric parameters and glucose metabolic indices before and after surgery.

RESULTSThe average age of patients in obesity and control group was (32.9±9.7) (18 to 56) years and (30.7±8.9) (18 to 49) years. Compared to the control group, obesity group had significantly higher anthropometric parameters and glucose metabolic indices before surgery (all P<0.05). In obesity group, the anthropometric and glucose metabolic indices significantly decreased at 1 to 6 months after surgery compared to those before surgery (all P<0.05). At 1 month after surgery, the anthropometric parameters and glucose metabolic indices in obesity group were significantly higher than those in control group (all P<0.05). At 3, and 6 months after surgery, there were no significant differences in glucose metabolic indices between obesity and control group (all P>0.05), while the anthropometric parameters in obesity group were still significantly higher than those in control group(all P<0.05). The sex hormone parameters in control and obesity group before surgery were as follows: E2: (100.2±23.5) pmol/L and (129.2±81.9) pmol/L; TT: (18.0±4.9) nmol/L and (8.4±4.5) nmol/L; FSH: (4.5±3.1) IU/L and (4.3±2.5) IU/L; LH: (4.4±1.7) IU/L and (5.3±2.6) IU/L. Compared to control group, the TT level of obese patients before surgery significantly decreased(P=0.000), while no significant differences were observed in the levels of E2, FSH, and LH(all P>0.05). The TT levels were significantly increased at 1, 3, 6 months after surgery[(13.1±7.0), (13.6±5.7), (21.0±19.3) nmol/L, respectively, all P<0.05] and the E2 level was significantly decreased at 6 months after surgery [(91.4±44.9) pmol/L, P<0.05], while no significant differences were observed at 1 and 3 months after surgery (all P>0.05). Furthermore, the FSH and LH levels did not exhibit significant change at 1, 3, and 6 months after surgery compared to those before surgery (all P>0.05). At 1 month after surgery, no significant correlations were examined in the change value of TT levels (▹TT) with the changes of BMI(▹BMI), FPG(▹FPG), FINS(▹FINS), HOMA-IR(▹HOMA-IR), and E2(▹E2) (all P>0.05). At 3 months after surgery, ▹TT was negatively correlated with ▹BMI (r=-0.441, P=0.015), ▹FINS (r=-0.375, P=0.041), and ▹HOMA-IR(r=-0.397, P=0.030), but not correlated with ▹FPG and ▹E2 (all P>0.05). At 6 months after surgery, ▹TT was negatively correlated with ▹BMI(r=-0.510, P=0.018) and ▹HOMA-IR (r=-0.435, P=0.049), but not correlated with ▹FPG, ▹FINS and ▹E2 (all P>0.05).

CONCLUSIONSMale severe obese patients are accompanied with abnormal sex hormone levels. LSG has a significant effect on weight loss and blood glucose improvement, and may ameliorate the sex hormone unbalance by improving the insulin resistance in men with severe obesity.

Adult ; Bariatric Surgery ; Blood Glucose ; physiology ; Body Mass Index ; Body Weights and Measures ; China ; Estradiol ; blood ; physiology ; Fasting ; blood ; Follicle Stimulating Hormone ; blood ; physiology ; Follow-Up Studies ; Gastrectomy ; Glycated Hemoglobin A ; physiology ; Humans ; Insulin ; blood ; physiology ; Insulin Resistance ; physiology ; Luteinizing Hormone ; blood ; physiology ; Male ; Obesity, Morbid ; surgery ; Retrospective Studies ; Testosterone ; blood ; physiology ; Treatment Outcome ; Weight Loss ; physiology

Objective To observe ransurethral flexible ureteroscopey for two-step precise method treatment of parapelvic cyst. Methods From May 2014 to November 2015, 23 patients of parapelvic cyst underwent a ransurethral flexible ureteroscopey for two-step precise method treatment, then analyze the clinical data of patients, observe the therapeutic effect. Results All patients underwent primary surgery successfully while 4 cases among them were confirmed as urine level puncture calyceal diverticulum treated with flexible ureteroscopy diverticulum expand drainage, the other 19 cases were confirmed as renal cyst and treated with cyst incision drainage successfully. The hemoglobin before and after surgery showed no changes. With no blood transfusion, the average postoperative hospitalization time was 2 d. 1 day after surgery, KUB was to locate the DJ tube position; 1 month later, ultrasound or CT check show that the cyst volume was significantly reduced, postoperative follow-up range from 6 months to 1 year. All the patients had no long-term complications. Conclusion Ransurethral flexible ureteroscopey for two-step precise method treatment of parapelvic cyst and renal pelvis lamp beside diverticulum provide a clear direction for the next operation. It's simple operation with no significant complications and recovered quickly, which is an ideal method for the treatment of renal pelvic.

Objective: To analyze the exposure level and the geographical distribution trend of toxicological indicators of rural drinking water in Shandong Province. Methods: The drawing method was used to randomly select no less than 60% villages and towns from 137 counties (cities, districts) of 17 cities in Shandong Province in 2015, and then 1-3 rural centralized water supply units were selected according to the circumstance of rural centralized water supply units in each village and town. In total, 735 villages and towns, 1 473 rural centralized water supply units were selected, and 1 473 water samples were collected. The water treatment process, water supply population and other circumstances of the rural centralized water supply units were investigated, the water quality was monitored, the content of toxicological indicators of drinking water in different areas was compared, and the trend surface isogram of excessive toxicological indicators was drawn. Results: The qualified rate of toxicological indicators in 1 473 water samples was 83.64% (n=1 232). The main toxicological indicators that affected the qualified rate of toxicological indicators of drinking water in rural areas in Shandong Province were nitrate and fluoride. The excessive rate of fluoride was 5.70% (n=84) and the exposed population was 1 736 709 (4.22%). The excessive rate of nitrate (as nitrogen) was 12.29% (n=181) and the exposed population was 1 393 612 (3.39%). The P₅0 content of fluoride in the eastern, middle and western regions was 0.24, 0.29 and 0.59 mg/L, respective;which was higher in the western region than in the east and the middle regions (P<0.05). There was no significant difference between the eastern and the middle regions (P>0.05). The P₅₀ content of nitrate (as nitrogen) in the eastern, middle and western regions was 8.00, 7.48, and 2.00 mg/L, which was higher in the eastern and middle regions than in the west region (P<0.05), there was no significant difference between the eastern and the middle regions (P>0.05). The trend surface isogram of nitrate and fluoride content showed that the content of nitrate (as nitrogen) in rural drinking water in the eastern region was significantly higher than that in the western region, especially there was a high peak area in the northeastern region, and this high content distribution extended diagonally to the central region, while the other regions were in a relatively low range. The content of fluoride in rural drinking water in the western region was significantly higher than that in the eastern region, and there were high peaks in the southwest and northwest regions, and the other regions were in a relatively low range. Conclusion The high exposed toxicological indicators in rural drinking water in Shandong Province were nitrate (as nitrogen) and fluoride, and their distribution showed obvious geographical distribution trend.

OBJECTIVE: To study the biological exposure limit of 1,3-butadiene occupational exposure. METHODS: A total of 139 workers who exposed to 1,3-butadiene in a rubber plant was chosen as exposure group,and 45 workers without 1,3-butadiene exposure were chosen as control group by judgment sampling method. Gas chromatography-flame ionization detection method was used to detect the level of 1,3-butadiene in workplace air,and ultra-high performance liquid chromatography-tandem mass spectrometric was used to determine the level of urinary dihydroxybutyl mercapturic acid( DHBMA) in end-of-shift workers. The correlation between 1,3-butadiene level and urinary DHBMA level was analyzed.The biological limit of 1,3-butadiene occupational exposure was assessed. RESULTS: The range of concentration-time weighted average( C_(TWA)) of 1,3-butadiene was from 0. 004 to 7. 609 mg/m~3,the medium was 0. 253 mg/m~3 in the exposure group,while the level of urinary DHBMA was from 0. 171 to 4. 235 mg/g Cr,and the medium was 1. 220 mg/g Cr. The range of C_(TWA)of 1,3-butadiene was below detection limit in the control group. The level of urinary DHBMA was from 0. 157 to 1. 808 mg/g Cr,and the medium was 0. 627 mg/g Cr in the control group. The level of urinary DHBMA in the exposure group was higher than that of the control group( P < 0. 01). The level of urinary DHBMA( y) of workers was related to the level of 1,3-butadiene( x) of the workplace air in the exposure group( y = 0. 349 x + 1. 082,P < 0. 01).CONCLUSION: DHBMA in urine could be used as a biomarker for 1,3-butadiene exposure in workers. The recommended biological exposure limit of DHBMA is 2. 900 mg/g Cr.