It is necessary to have a research on dental fluorosis in a population to minimize the prevalence and severity of caries.It is important to research the pathogenesis of enamel fluorosis and prevention and control of dental fluorosis and caries.This article reviews the progress in chemistry and biology of dental fluorosis.

Objective To explore the clinical value of multi-slice CT in distinguishing between benign parotid tumors and malignant parotid tumors. Methods CT scanning images of 72 parotid tumor patients were analyzed. The location, shape, density, edge, cystic necrosis and degree of enhancement of the tumors were analyzed, de-gree of cervical lymph node swelling were analyzed, and all the analysis results were compared to pathological re-sults. Results 80 lesions were diagnosed in tumors, among which 59(73. 8%) lesions were benign tumors and 21 (26. 2%) lesions were malignant tumors. The CT images of benign tumors showed that 42(71. 2%) of them were located in the superficial lobe and with regular shape and uniform density;62.7% of them had clear edge;57 . 6%of them showed mild or moderate enhancement. 2 cases of benign tumors presented cervical lymph node swelling, which were proved to be pathological inflammatory mass after operation. Whereas in the CT images of malignant tumors 12( 57. 1%) of them were located in the deep lobe or in both of the superficial lobe and the deep lobe. 15 (71. 4%) of them had irregular shape and uneven density. 81% of them had unclear edge. 71. 4% of malignant tumors were significantly enhanced. 9 cases of malignant tumor were with cervical lymph node metastasis. There was statistical difference between the shape, edge, density, cystic necrosis, degree of enhancement and cervical lymph node metastasis of the two groups of tumors(P<0.05), while the location and the degree of enhancement of the two groups of tumors showed no statistical difference ( P>0.05 ) . Conclusion Most of benign and malignant parotid tumors can be correctly diagnosed by analyzing multi-slice CT images.

Objective To study the effects of the early diagnosis and treatment of sleeve fractu re of patella in children.Methods The retrospection study was done to a nalyse the effects of the diagnosis a nd treatment of ten samples of sleeve fr acture of patella in our hospital fro m 1993to 2001.Results The diagnosis was confirmed by the characteristic s of the tension swelling of the knee,high position of the patella and a sle eve fractured fragment in the patella.T he operations were the main initial t reatment to regain the proper reduction.After 4weeksfixation the patients did knee exerc ises.And the curative effects were q uite good.Conclusion The sleeve fracture of the patella in children is easy to be misdiagnosed o r missed because of the cartilage.So it is the more important to be able to con duct an early diagnosis and treatmen t for the better prognosis.

Objective To investigate the changes of buffy coat components after 25Gy 137Cs-irradiation.Methods Lymphocyte proliferation was detected by MTT,the fluorescent intensity of neutrophils was measured as phagocytotic rate by flow cytometry,O2-release was determined by cytochrome C reduction,and cytokine production pre-and post-irradiation was detected by ELISA.Results 25Gy is adequate to inactivate T cells.The percentages of phagocytosis of E.coli before and after irradiation were of no significant difference.The release of O2-increased significantly and monocytes maintained the ability to produce cytokines after irradiation.Conclusion Radiation does affect the components of buffy coat,and neutrophils isolated should be transfused as early as possible.

ObjectiveTo investigate the prevalence and distributing feature of atrial fibrillation (AF) in Xinjiang Kazaks adult population.MethodsFour-stage selected random samples aged 30-89 years from Tacheng,Yili and Aletai were analyzed.An epidemical study of AF was performed including inquiring medical history,recording electrocardiogram and auscultation. ResultsA total of 22 514 adults were surveyed.The prevalence of AF in Xinjiang Kazaks adult population was 0.37％,which was increasing with aging.The prevalence was higher in men than in women (0.5％ vs 0.2％,P ＜0.01 ).In AF patients,23 was valvular AF.Ischemic stroke was the most frequent type and the stroke rate in the patients with AF was significantly higher than that without AF (6.0％ vs 1.2％,P ＜ 0.01 ).ConclusionsThe prevalence of AF in Xinjiang Kazaks adult population is lower than the reported national prevalence but patients with AF in this population would not like to take the necessary medicine. Therefore,the control of AF need to be reinforced.

Objective To summarize the lung HRCT findings of lung Langerhans cell histiocytosis (LCH) in children. Methods A total of 54 children with lung LCH pathologically proved in our institute from September 2006 to December 2014 were retrospectively reviewed. Patients were subdivided into two subgroups, diffuse type (n=29) and localized type (n=25). In addition, 32 children with LCH but without pulmonary infiltration were selected as control group. HRCT findings of 54 LCH with lung involvement were reviewed and analyzed for distribution pattern. The age of onset, illness duration and pulmonary function were compared between the lung LCH group and the control group. The differences of HRCT findings in LCH patients between diffuse type and localized type were compared with χ2 test. The differences on the onset age, illness duration and pulmonary function between the LCH group with lung involvement and control group were compared with non-parametric test(Mann-Whitney U Test). The differences of pulmonary function between the LCH group with lung involvement and control group were compared with Fisher exact probability test. Results The signs of pulmonary LCH on HRCT included lobular hyperinflation (n=26), interlobular septa thickening (n=11), cystic lesions (n=11), ground?glass opacity (n=10), nodules (n=9), and centrilobular nodules (n=6). The signs presented in 21, 8, 7, 9, 4 and 6 cases in diffuse type group respectively and 5, 3, 4, 1, 5, 0 in localized type group. Among them, lobular hyperinflation, ground?glass opacity and centrilobular nodules were more prevalent in the diffuse group. The difference was statistically significant (χ2=14.77,2.01,0.55,4.84,0.06 and 3.91, P<0.05). The onset age of LCH group with lung involvement was younger than the other (Z=-2.40, P<0.05). However, there was no statistically significant difference in the illness duration (Z=-1.46, P>0.05) and pulmonary function between two groups (P>0.05). Conclusions Lobular hyperinflation, ground glass opacity and centrilobular nodules are the most common manifestations in LCH patients with lung involvement and the distribution is mostly diffuse. Nodules, cystic lesions and interlobular septa thickening may exist. Several signs may coexist simultaneously. Younger children with LCH are more vulnerable to lung involvement.

Objective To measure the average value of CT lung density at the phase of end inspiration and end expiration in children under 5 years.Methods Sixty patients with normal lungs who underwent chest CT for reasons caused by trauma etc.in our institute from January 2010 to March 2012 were enrolled to the study.All of the patients were divided into end inspiration group and end expiration group through random number table.CT images of the phase of end inspiration and end expiration were taken.Three levels of CT images were chosen to measure the lung density,which were 2 cm above the arch,1 cm below the carina and 2 cm above diaphragm.Lung density was measured at anterior,posterior,lateral,medial and central of the images at each level in each lung.The average lung density of each and entire lung were respectively calculated.The influence of phase,level,location was quantified using analysis of variance methods and LSD method.Results The average lung density at end inspiration was (-766 ±56)HU for the left,right and both lung.At end expiration,the average lung density of the left,right and both lungs was (-625 ± 86),(-647 ± 85) and (-636 ± 86) HU respectively.The average densities at anterior,posterior,lateral,medial and central of the left lung at end inspiration were (-798±63),(-733±68),(-767±64),(-754 ±65),(-775 ±63)HU respectively.The average densities at anterior,posterior,lateral,medial and central of the right lung were (-796 ± 70),(-736 ± 65),(-769 ± 64),(-754 ± 62),(-776-± 59) HU respectively.At end expiration phase,the average densities at anterior,posterior,lateral,medial and central of the left lung were (-692±91),(-555±116),(-639±91),(-598±103),(-640±98) HU respectively.The average densities at anterior,posterior,lateral,medial and central of the right lung were (-712 ± 90),(-575±121),(-657±90),(-619±95),(-670±87) HU respectively.The statistical differences of these five measurement areas were significant at both inspiration and expiration phase (F=12.55,11.29,23.31,25.47,P＜0.01).The posterior lung density was the highest and the anterior was the lowest.As for the other measurement areas,in descending order were medial,lateral,and central.Conclusion The lung density at end inspiration and end expiration in children under 5 years old is described to provide reference for the clinical work.

Objective To explore the CT findings of pediatric hepatoblastoma and its correlation with pathological subtypes.Methods CT findings and pathological characteristics of 110 patients with hepatoblastoma confirmed by pathology were retrospectively analyzed.Results The locations of the tumor were right lobe (67/110,60.90％),right and left lobe (25/110,22.72％),left lobe (15/110,13.63％) and caudate lobe (3/110,2.72％).The average tumor size was (287.14±272.36) cm3.Most cases were solitary (94/110,85.45％) and round shape (96/110,87.27％).Most cases were well defined (86/110,78.18 ％).Necrosis were irregular in 102 cases,calcification were in 60 cases.Lung metastases were common (23/110,20.90 ％) and vessel involvement were common (56/110,50.90 ％).Lymph node metastasis was in 5 cases.Calcification and homogeneous enhancement in different pathological types had statistically significance (both P ＜0.001).Conclusion CT is helpful for pre-operation and pathological diagnose.

0.05).Conclusion:The CT perfusion parameters can be regarded as a surrogate marker of tumor angiogenic activity,which is a useful method in estimating the degree of angiogenesis.

Objective To compare the CT findings of different phases in pediatric hepatoblastoma (HB) based on PRETEXT system in order to optimize pediatric HB CT scan protocol. Methods A total of 58 HB patients who were surgical and pathological diagnosed from January 2015 to December 2016 were analyzed. Pre-operation CT exams were analyzed respectively. Observing items included tumor size, intra-abdominal invasion, bleeding, intrahepatic metastasis, lymphatic metastasis, metastasis (except lymphatic in abdomen) main portal vein, three main hepatic vein, inferior vena cava (IVC) invasion, para-tumor hepatic arteries, and its branches. All image findings were compared to pathological and surgical findings to calculate the agreement rate. Exact Fisher test and R × C χ2 test were used. Results According to the surgery and pathological results, the agreement rate of tumor size was n=40 (68.9%) at non-contrast phase, n=43 (74.1%) at artery phase and n=52 (91.2%) at venous phase. Venous phase was adaptive for observing tumor size (χ2=8.16,P=0.018). For main portal vein, three main hepatic vein, and IVC invasion, none was found at both non-contrast and artery phase. N=12 (20.7%, P<0.001) was found at venous phase. For para-tumor hepatic arteries, and its branches, none was found at non-contrast phase. N=46 (79.3%) was found at artery phase. N=17 (29.3%) was found at venous phase. Artery phase was adaptive for observing (P<0.001). There was no statistical significant difference in intrahepatic metastasis, lymphatic metastasis and metastasis. Conclusions Suspected pediatric HB, artery and venous phase CT scan would meet the clinical requirement, there was no need for non-contrast pahse. Follow up cases, a single venous phase was enough. Venous phase contributed much more information on tumor size and high risk prognosis evaluation.