Objective To establish a three-dimensional finite element model of pelvic anteroposterior compression (APC) for analysis of mechanisms for related liganentous damages.Methods A finite element model and a laboratory mechanical model of APC were established using the same pelvic specimens.In a finite element model of normal pelvic bones and ligaments,after the right pelvis was fixated the pubic symphysis (PS) was sectioned.Next,a manual external mobile force was gradually applied to the left hemipelvis to make the PS diastasis 10,20,30,40,60,80 and 100 mm apart.The mechanical experiment revealed the anterior sacroiliac ligament (ASIL) was ruptured when the PS diastasis reached 28 mm.After the strain value of ASIL was calculated through the finite element model,it was applied to the other pelvic ligaments.The displacement in front of the sacroiliac joint (SIJ),stress,strain and extent of injury and disruption of sacrotuberous/sacrospinous ligaments (STL/SSL) with a corresponding PS diastasis were observed and recorded.Results ASIL failed at the point when the PS diastasis was 28 mm and the displacement in front of SIJ was 7.41 ± 1.14 mm.The strain and maximum principal stress of ASIL calculated in the finite element model were 259.5％ and 543.24 MPa respectively.The maximum principal stress value of SSL was 35.00 MPa at the point of failure when the PS diastasis and the displacement in front of SIJ were 51 mm and 15.23 ±2.88 mm,respectively.When the PS diastasis and the displacement in front of SIJ were 100 mm and 7.5 mm respectively,the maximum principal stress value of STL was 16.17 MPa but the strained ligament was not ruptured.When the pelvis was rotated externally step by step,the ASIL failure was followed by the rupture of SSL but not necessarily by the STL failure.Conclusion As the finite element pelvic bone-ligament model established in this study can effectively simulate the mechanisms for APC injury,it can be used to evaluate different extents of pelvic ligamentous injury,providing a basis for the biomechanical study of pelvic bones and ligaments.

Objective:To understand the situation of drinking water-borne endemic fluorosis (short for drinking water fluorosis) in Huangzhong, Ping'an and Ledu districts of Qinghai Province and operation status of water improvement projects, and to evaluate the effect of control measures.Methods:In historical drinking water fluorosis villages of Huangzhong, Ping'an and Ledu districts of Qinghai Province in 2018, the status of water improvement, the operation of water improvement projects and the content of water fluoride were investigated; the dental fluorosis of 8-12 years old children in all investigated villages was checked; 3 villages from 3 districts were selected, X-ray examination for skeletal fluorosis and urinary fluoride detection of adults over 25 years old of age were performed.Results:Eight-two historical drinking water fluorosis villages in 3 districts were investigated and all the villages had water improvement projects, in addition, the water improvement projects were operating normally, and the water fluoride content ranged from 0.10 to 0.37 mg/L, which were in line with the drinking water fluoride content standard (< 1.2 mg/L). Totally 2 503 children aged 8-12 years old were examined, the detection rate of dental fluorosis was 6.03% (151/2 503), the index of dental fluorosis was 0.13, the epidemic intensity was negative; the detection rates of dental fluorosis in 3 districts were 6.24% (129/2 068), 4.05% (7/173), 5.73% (15/262), respectively, reaching the control standard (< 30%), and the detection rate of dental fluorosis in 81 villages was less than 30%; 198 adults over 25 years old were examined, the detection rate of skeletal fluorosis was 5.05% (10/198), the geometric mean of urinary fluoride was 0.81 mg/L, and skeletal fluorosis cases were mainly in the age group over 40 years old, all of them were mild cases.Conclusions:The fluoride content in drinking water and the detection rate of children's dental fluorosis are all up to the control standard, and the condition of skeletal fluorosis is significantly reduced after the implementation of water improvement measures in Huangzhong, Ping'an and Ledu districts. It can be seen that the prevention and control of drinking water fluorosis in Huangzhong, Ping'an and Ledu districts have achieved good results, but later management and condition monitoring of water improvement projects should be strengthened to prevent the disease from rebounding.

Objective To understand the current environmental selenium and T-2 toxin levels in the critically ill areas of Kaschin-Beck disease in Qinghai Province.Methods In three historical villages with serious diseases of Kaschin-Beck disease,Xia,Xiemalang and Yaoshidao were selected;at the same time,three villages from non-diseased areas were selected as control villages including Damitan,Gongba and Deang in 2018.Six villages were used as survey sites.Collected hair samples of children aged 6-12 years old,to measure the hair selenium content in Xinghai and Guide survey sites [children's selenium content reference value was (0.60 ± 0.03)mg/kg].Ten samples of self-produced grain were collected from each survey site,selenium content [wheat selenium content reference value was (0.053 ± 0.007) mg/kg] and T-2 toxin content in grain was detected in the six survey sites.Ten soil samples were collected from each survey sites.Soil selenium content was detected in the six survey sites [soil selenium content reference value was (0.24 ± 0.03) mg/kg].Results The selenium contents of children's hair in the diseased and non-diseased areas of Xinghai County,Guide County were (0.252 ± 0.071),(0.296 ± 0.087);(0.225 ± 0.032),(0.238 ± 0.040) mg/kg,respectively.The selenium contents of wheat in the diseased and nondiseased areas of the three counties were 0.000 19,0.003 66;0.000 15,0.004 16;0.016 78,0.016 94 mg/kg.The soil selenium contents in the diseased and non-diseased areas of the three counties were (0.095 ± 0.015),(0.114 ± 0.014);(0.082 ± 0.013),(0.083 ± 0.018);(0.080 ± 0.005),(0.060 ± 0.013) mg/kg.The T-2 toxin contents of wheat in the diseased and non-diseased areas of the three counties were (3.173 ± 0.762),(3.100 ± 0.473);(2.506 ± 0.430),(3.186 ± 0.451);(2.416 ± 0.619),(2.879 ± 0.456) μg/kg.Conclusions The content of hair selenium of children is close to the normal reference value in the area of Kaschin-Beck disease in Qinghai Province.The contents of soil selenium and the main grain selenium of the residents are low in the diseased village.A certain amount of T-2 toxin is detected in the main grain of residential households.

Objective:To investigate the effects of 3 treatment methods on serum cytokines in Kaschin-Beck disease (KBD) patients.Methods:In May 2015, according to "Diagnosis of Kaschin-Beck disease" (WS/T 207-2010), KBD patients with grade Ⅰ and above who lived in KBD areas of Guide, Xinghai and Banma counties of Qinghai Province for at least 25 years and aged 25 - 62 years old were selected as research subjects. Patients were divided into 3 groups according to different treatment methods. The first group ( n = 91) was treated with Celecoxib + Xiaohuoluo pill (concentrated pill), the second group ( n = 89) was treated with Celecoxib + bone-strengthening joint pill, and the third group ( n = 94) was treated with Celecoxib + anti-osteogenic tablet, and the overall treatment effects of 6 months after treatment of the 3 groups were compared and analyzed. The contents of serum nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and hyaluronic acid (HA) in patients before and after treatment were detected by enzyme-linked immunosorbent assay (ELISA). Results:A total of 274 KBD patients were included, aged (47.24 ± 18.97) years old, including 132 males and 142 females. The treatment effective rates in the first, second and third groups were 80.22% (73/91), 77.53% (69/89) and 77.66% (73/94), respectively, and there was no significant difference between the three groups (χ 2 = 0.25, P > 0.05). Before and after the treatment, the serum NO contents of the 3 groups [(149.23 ± 20.61), (135.88 ± 29.63), (151.33 ± 22.15), (137.55 ± 31.51), (148.58 ± 24.36), (134.81 ± 28.53) μmol/L] were significantly different ( t = 2.678, 2.403, 3.195, P < 0.05), and there were no significant differences in TNF-α, IL-1β, and HA contents ( P > 0.05). Conclusion:Three treatment methods for treating KBD have achieved certain effects, all the 3 treatment methods have reduced serum NO content and have no significant effect on TNF-α, IL-1β and HA contents.

Objective To dynamic monitor drinking-water-borne fluorosis in Huzhu County and water improvement projects,to know the trend of the disease,and to evaluate the effect of prevention and control measures.Methods Seven townships in Huzhu County including 60 history drinking-water-borne fluorosis villages were selected as investigation sites in 2017,and demographic data were collected.In the villages of the diseased areas where the water had been changed,the operation of the water improvement project was investigated,and 1 tap water sample was collected to determine the fluorine content;for the villages in the diseased areas where the water had not been changed,one water sample was collected from the drinking water source in accordance with the five directions of east,west,south,north and middle to determine the fluorine content.More than 90％ of the children aged 8-12 years old in the surveyed villages were examined and judged for dental fluorosis.According to historical data,1 village with severe illness of children was selected,50 people were selected who were over 25 years old and lived in the villages for more than 5 years.Clinical and X-ray examinations of skeletal fluorosis were performed.Urine samples from adults surveyed were collected for urinary fluoride detection.Results Six of the 60 villages in the 7 townships had been relocated.By 2017,a total of 54 villages in drinking-water-borne fluorosis areas had changed their water.A total of 16 water improvement project were surveyed,among them,there were small water improvement project 6,accounting for 37.50％,large water improvement project 10,accounting for 62.50％;normal operated project 16,accounting for 100.00％;water fluoride content of qualified project 16,the qualified rate was 100.00％,the water fluoride content ranged 0.10-0.66 mg/L,covering a population of about 160 thousand and 846 people.A total of 2 399 children aged 8-12 were examined,117 cases of dental fluorosis were detected,the detection rate of dental fluorosis was 4.88％,dental fluorosis index was 0.13.Among them,89 cases were extremely mild,accounting for 3.71％ of all the children examined,21 cases were mild,accounting for 0.88％ of all the children examined,7 cases were moderate,accounting for 0.29％ of all the children examined,and no severe cases were found.A total of 68 adults over 25 years old were examined for skeletal fluorosis.Twelve patients were found to have clinical skeletal fluorosis.The detection rate was 17.65％.X-ray radiography was used to examine 46 people,and 1 case was detected,the detection rate was 2.17％.Clinical and X ray examinations showed no more than moderate patients.Fifty samples of adult urine were tested,the level of urine fluorine was 0.72 mg/L.Conclusions Water improvement project is working well in Huzhu County,and no serious children with dental fluorosis and adult skeletal fluorosis are detected.The prevention and control measures of drinking-water-bornefluorosis has achieved remarkable results in Huzhu County.We will continue to strengthen water improvement project and disease monitoring,and thoroughly control the prevalence of drinking water fluorosis.

Objective:To observe and evaluate the effect of health education on drinking brick-tea type fluorosis in Zhiduo County, Qinghai Province, so as to provide basis for further formulating health education strategies.Methods:From April 2019 to April 2020, according to the historical prevalence of drinking brick-tea type fluorosis in Zhiduo County, Qinghai Province, 3 townships (towns) were selected to carry out the health education activities on drinking brick-tea type fluorosis for students of grade 4 - 6, village doctors, adults and monks in each township (town). We carried out a one-year publicity on the prevention and treatment of drinking brick-tea type fluorosis, distributed health education materials and organized health education activities. Before and after the intervention, we conducted a questionnaire survey on health education among the target population (grade 4 - 6 students, village doctors, adults and monks), to evaluate the awareness rate and behavior formation rate of fluorosis prevention and control, and to evaluate the intervention effect.Results:A total of 86 students of grade 4 - 6, 40 village doctors, 42 adults and 20 monks were investigated, after the intervention, the awareness rates of prevention and treatment of drinking brick-tea type fluorosis in grade 4 - 6 students, village doctors, adults and monks were 87.98% (227/258), 96.67% (116/120), 81.75% (103/126), 83.33% (50/60), respectively, which were significantly higher than those before the intervention [38.38% (76/198), 83.33% (100/120), 15.45% (19/123), 28.89% (13/45), P < 0.05]. After the intervention, the behavior formation rates of prevention and treatment of the drinking brick-tea type fluorosis in grade 4 - 6 students, village doctors, adults and monks were 74.42% (128/172), 72.50% (58/80), 52.38% (44/84), 60.00% (24/40), respectively, which were significantly higher than those before the intervention [14.39% (19/132), 38.75% (31/80), 3.66% (3/82), 0(0/28), P < 0.05]. Conclusion:The comprehensive intervention measures based on health education can significantly improve the knowledge of local residents, and improve their bad drinking habits of drinking tea, which is of great significance to the prevention and treatment of drinking brick-tea type fluorosis.

Objective:To observe the changes of serum C-terminal peptide of type Ⅰ collagen (CTX-1) and N-terminal lengthening peptide of type Ⅰ collagen (P1NP) in adult patients with skeletal fluorosis in the tea-drinking-borne endemic fluorosis area in Qinghai Province, and to find sensitive indicators for diagnosis of skeletal fluorosis.Methods:From April to August 2019, a case-control study was carried out in tea-drinking-borne endemic fluorosis area in Zhiduo County, Yushu Tibetan Autonomous Prefecture, and Gangcha County, Haibei Tibetan Autonomous Prefecture of Qinghai Province. According to the Diagnostic Standard for Endemic Skeletal Fluorosis (WS/T 192-2008), the clinical diagnosis and X-ray examination of skeletal fluorosis were carried out for permanent residents ≥25 years old and living for more than 10 years in the area, combined with face-to-face inquiry and investigation of past disease history, lifestyle and clinical manifestations. The patients with skeletal fluorosis and healthy people were selected as skeletal fluorosis group and control group, respectively. Randomized urine samples and fasting venous blood from the two groups were collected. The content of fluoride in urine was determined by ion selective electrode method, and the contents of CTX-1 and P1NP in serum were determined by enzyme-linked immunosorbent assay (ELISA).Results:A total of 127 people in the disease area were investigated, including 63 cases in skeletal fluorosis group and 64 cases in control group. There was no statistically significant difference in age and sex ratio between the two groups ( t = 0.42, χ 2 = 0.07, P > 0.05). The X-ray examination results showed that the patients with skeletal fluorosis were mainly mild, accounting for 71.43% (45/63); X-ray changes were mainly ossification of interosseous membrane and tendon. The urinary fluoride in control group and skeletal fluorosis group was 1.62 (1.12, 1.95) and 3.22 (2.38, 4.89) mg/L, respectively, with statistically significant difference between the two groups ( Z = 7.07, P < 0.001). The difference of serum CTX-1 and P1NP contents between the two groups was statistically significant ( Z = 2.00, 4.89, P < 0.05). Conclusions:The levels of serum CTX-1 and P1NP in patients with skeletal fluorosis are higher than those in healthy people. Serum CTX-1 and P1NP may be used as sensitive indicators for diagnosis of skeletal fluorosis.

Objective To understand the epidemic situation of tea-drinking-borne fluorosis among children in Haixi Prefecture of Qinghai Province,and to provide basis for taking pertinent prevention and control measures.Methods In 2017,three townships (towns) were selected from five counties (cities) in Golmud,Delingha,Dulan,Ulan and Tianjun,Haixi,and one village (villages excluding excessive water fluoride) was selected from each township (town) as the investigation site.Fluoride content in drinking water,tea fluoride content and dental fluorosis in children aged 8-12 years were investigated.Water fluoride was determined using "Standard Test Method for Drinking Water" (GB/T 5750.5-2006);brick tea fluoride content was detected using "The Fluoride Content in Brick Tea" (GB 19965-2005);children's dental fluorosis was diagnosed using "Diagnosis of Dental Standard for Fluorosis"(WS/T 208-2011).Results Totally 75 drinking water samples were collected from each county (city).The water fluoride content ranged from 0.35 to 0.41 mg/L,with an average value of 0.37 mg/L,which was lower than the national drinking water fluoride standard of 1.00 mg/L.The fluoride content of 150 brick tea samples ranged from 206.0 to 796.0 mg/kg,with an average value of 629.8 mg/kg.A total of 1 325 children aged 8-12 were examined.The detection rate of dental fluorosis was 13.43％ (178/1 325),the index of dental fluorosis was 0.27,and the overall epidemic intensity was negative.The epidemic intensity in Dulan and Tianjun counties was marginal.There were significant differences in the detection rate of dental fluorosis among children of different ages (x2=35.26,P ＜ 0.05),and dental fluorosis was increased with ages in children.The detection rate of dental fluorosis in boys and girls was 13.31％ (90/676) and 13.56％ (88/649),respectively,with no significant difference (x2 =0.02,P ＞ 0.05).Conclusions There is an epidemic of tea-drinking-borne fluorosis among children in 5 counties (cities) of Haixi Prefecture.Although the epidemic is mild,it should not be ignored.Health education and publicity work for tea-drinking-borne fluorosis should be strengthened.