Objective To investigate image quality and radiation dose of prospective ECG-gated coronary combined with carotid and cerebrovascular angiography and compare it with common coronary CTA and carotid-cerebrovascular CTA at a 256-slice spiral CT.Methods Fifty-seven patients were included in the study.The data was analyzed retrospectively and divided into 3 groups.Group 1 underwent coronary combined with carotid CTA ( n =17 ),which included a wide range of prospective ECG-gated coronary,carotid and cerebral vascular one-stop angiography.Group 2 underwent coronary CTA ( n =20),which was routine prospective ECG-gated coronary angiography.Group 3 underwent routine carotid and cerebrovascular CTA (n =20).Mean CT image attenuation and image noise were measured in the ascending aorta root,proximal parts of the bilateral common carotid artery and vertebral artery,and in the internal carotid artery at sellae level in the axial plane.Coronary artery image quality was rated using a four-point ordinal scale and carotid cerebral vascular image quality was rated using a three-point ordinal scale.Radiation dose were calculated.Mean CT image attenuation,image noise and radiation dose were compared among the 3 groups using t test.Using Mann-Whitney U,the coronary artery imaging quality was compared between group 1 and 2,and image quality of cerebral vessels was compared between group 1 and 3.Results Mean CT image attenuation [ (427 ±50) HU in group 1 and (426 ±86) HU in group 2] and image noise of the ascending aorta root [ (30 ± 9) HU in group 1 and (31 ± 9) HU in group 2 ] showed no statistical difference between group 1 and 2 (t =0.058,-0.325,P ＞0.05).There were no non-diagnosis coronary segments in group 1 and 2.And coronary segments with excellent or good image quality reached 98.1％ (202/206) in group 1 and 99.6％ ( 244/245 ) in group 2.It showed no significant difference between group 1 and 2 ( Z =-0.572,P ＞ 0.05 ).There were significant differences of mean CT image attenuation in the common carotid artery between group 1 [ ( 474 ± 70 ) HU ] and group 3 [ ( 348 ± 81 ) HU ],and in the vertebral artery between group 1 [(447 ±83)HU] and group 3 [(328 +66) HU] (t =5.043,4.869,P＜0.05).However,there was no significant difference of mean CT image attenuation in the internal carotid artery [ (370 ± 92) HU in group 1 and ( 367 ± 97 ) HU in group 3 ] ( t =0.111,P ＞ 0.05 ).There was a significant difference of image quality scores of carotid and cerebrovascular arteries between group 1 and 3 (Z =- 3.306,P ＜ 0.05 ).Effective radiation dose of groups 1,2,3 were ( 7.0 ± 0.8 ),( 3.1 ± 0.4 ) and (5.0 ± 0.3) mSv respectively.Conclusion The prospective ECG-gated coronary combined with carotid and cerebrovascular angiography is able to obtain diagnostic image quality of coronary,carotid and cerebral vascular at the 256-slice spiral CT.It is a simple,fast,noninvasive way to assess coronary and carotid cerebrovascular arteries,with advantages of less contrast medium and low radiation dose.

Objective To compare the image quality and patient radiation dose of coronary computed tomography angiography (CCTA) received by prospectively-gated step-and-shoot (SAS) technique with those obtained by retrospectively-gated spiral (RGS) technique on a 256-slice CT scanner. Methods A total of 200 patients were enrolled in this study. One hundred patients underwent CCTA with SAS mode were subdivided into two groups: ( 1 ) 50 patients with an average heart rate (HR) ≤70 bpm were scanned with a data acquisition time window centered at the 75％ of the R-R cycle ( group A) and (2) 50 patients with HR ＞ 70 bpm were scanned with the data acquisition time window centered at the 45％ of the R-R cycle, including a phase tolerance of ±％ (group B). Other 100 patients underwent CCTA with RGS mode and ECG-based tube current modulation were also subdivided into two groups: (3) 50 patients with HR ≤70 bpm were scanned with cardiac dose right set to phase of 75％ (group C) and (4) 50 patients with HR ＞ 70 bpm were scanned with cardiac ose Rdight set to phases of 45％ and 75％ (group D). All patients were grouped in randomized order. The image quality of CCTA were evaluated using a rank scale from 1 to 4 ( 1 : excellent ; 4 : non-assessable ) .Radiation dose of the four groups received was also estimated. The image quality between groups was compared by Mann-Whitney U test.The radiation dose between groups was compared by t test. For the 100 patients received by prospective ECG-gated CCTA, the receiver operating characteristic curve (ROC) was used to analyze the CCTA image quality and average heart rate to determine the uppercutoff of HR for obtaining diagnostic coronary images with SAS mode. A spearman correlation analysis was also performed to analyze the correlation of HR and image quality in patients underwent CCTA with SAS mode.Results Of 2338 coronary artery segments, excellent or good image quality( score of 1 or 2) was achieved in 96. 5％ (585 of 606) in group A, 77.7％ (445 of 573 ) in B,96. 1％ (548 of 570) in C, and 85. 7％ (505/589) in D, with no significant difference for A vs C(Z ＝- 1. 351 ,P ＞0. 05) and with significant differenceS for B vs D (Z＝ -2. 236,P ＜0. 05). Linear correlation analysis indicated a significant degradation of image quality with the increase of heart rate using SAS mode (Spearman correlation, r ＝ 0. 577, P ＜0. 01 ). ROC analysis established an upper HR threshold of 78 bpm for obtaining diagnostic image quality using SAS mode( AUC ＝ 0. 827, P ＜ 0. 05 ). The average radiation dose in group A [ ( 2. 6 ± 0. 5 ) mSv]reduced 75 ％ comparing with that in group C [ ( 10. 6 ± 2. 3 ) mSy], and the average radiation dose in group B [ ( 4.0 ± 0. 7 ) mSy]reduced 69％ comparing with that in group D [ ( 13.0 ± 1. 4) mSv]. ConclusionUsing SAS mode to perform low-dose CCTA with 256-slice helical CT could keep the image quality and reduce radiation dose significantly. Our preliminary experience suggests a good promise of this technique which could be applied to a wider group of patients such as with higher heart rates.

Aiming at the new problems in orthodontics teaching and employment,this study aims to explore a more suitable undergraduate teaching mode of Orthodontics,and reform the teaching of Orthodontics for five-year program students in department of stomatology of Xi'an Medical University.During the teaching of Orthodontics,teachers use the aesthetic principles that students have learned to integrate into the orthodontics teaching,and guide students to analyze,understand and master orthodontic knowledge based on the principles of aesthetics.After the course,students give good feedback on the teaching reform,and their scores of basic knowledge and case analysis of Orthodontics theoretical examination have been improved.This teaching reform is very helpful for students to learn,understand and master the knowledge of orthodontics.It helps to improve classroom teaching effect,improve students' interest in learning,and adapt to the needs of discipline and industry development,so it is worth studying and promoting.

Objective To study the effect of magnesium/selenium on the expression of matrix metalloproteinases-20(MMP-20) and kallikrein 4(KLK4) during fluorosis in mice and to explore the formation mechanism of dental fluorosis.Methods Eighty SPF male ICR mice were randomly divided into 8 groups according to body weight:control group,magnesium group,selenium group,magnesium-selenium group,fluoride group,magnesium-fluorine group,selenium-fluorine group and magnesium-selenium-fluorine group.Mice in control,magnesium,selenium and magnesium-selenium groups were fed double steamed water,and mice in the other four groups were feddouble steamed water with 50 mg/L F.Mice in control and fluoride groups were fed conventionally.Mice in magnesium and magnesium-fluorine groups were fed conventionally by adding MgSO4·7H2O 162.5 mg/kg.Mice in selenium and selenium-fluorine groups were fed conventionally by adding Na2SeO3·5H2O 2 mg/kg.Mice in magnesium-selenium and magnesium-selenium-fluorine groups were fed conventionally by adding MgSO4· 7 H2O 162.5 mg/kg + Na2SeO3·5H2O 2 mg/kg.Incisor specimens were obtained after the mice were put into death when they were 42 days.The expressions of MMP-20 and KLK4 were observed by using immunohisto-chemicalstain.Results The meangray value of MMP-20 of fluoride group(133.1±10.3) was significantly higher than that of control group(116.8±10.0),magnesium group (113.6 ± 9.6),magnesium-selenium group(108.2 ± 15.2),magnesium-fluorine group(Ill.1 ± 8.1) and magnesium-selenium-fluorine group(108.2 ± 11.0),respectively(F=3.864,P＜0.05).The mean gray value of MMP-20 of magnesium-selenium-fluorine group(108.2 ± 11.0) was significantly lower than that of selenium group(125.4 ± 7.9),fluoride group (133.1 ± 10.3) and selenium-fluorine group(126.2 ± 2.8),respectively(F=3.864,P＜0.05).The mean gray value of KLK4 of magnesium-selenium group(117.2± 11.7) was significantly lower than others(137.3±7.9 of control group,144.2±7.7 of magnesium group,138.9±13.3 of selenium group,149.7± 12.4 of fluoride group,148.9±7.5 of magnesium-fluorine group,140.6± 17.0 of selenium-fluorine group and 140.7 ± 7.3 of magnesium-selenium-fluorine group,F=3.668,P＜0.05).In factorial analysis of fluorosis mice,magnesium had effect on the expression of MMP-20(F=42.613,P＜0.05),selenium had effect on the expression of KLK4(F=6.649,P＜0.05).Conclusions The excessive fluoride could inhibit the expressions of MMP-20.The excessive fluoride hadno significant influence on the expression of KLK4.Magnesium and selenium had antagonistic effect on the dental fluorosis.

With wide applications of radiation therapy in the treatment of cancer and other diseases and amid the in-creasing concerns about global nuclear safety,the research and development of drugs against radiation damage has become a hot spot.Thanks to its high energy properties,ionizing radiation can not only directly damage cell DNA through targeted effects,but also indirectly affect the cell environment through non-targeted effects,leading to cell dysfunction and even death.In this paper,the mechanism of ionizing radiation damage was analyzed,and the mechanisms of action and clinical applications of four types of anti-radiation drugs,namely,antioxidant,apoptosis inhibitor,cytokine and natural radiation protection agent were discussed.These drugs have huge implications for alleviating the targeted and non-targeted effects caused by ionizing radiation.

We studied the patients diagnosed with X-linked hypophosphatemicrickets(XLH) and treated with burosumab in Peking Union Medical College Hospital from January 2021 to December 2022. In addition, we described the clinical characteristics of the patients, the changes of clinical indexes before and after burosumab treatment, and the adverse drug reactions during treatment. We also evaluated the efficacy and safety of burosumab for XLH. The results showed that three children XLH patients and one adult XLH patients received burosumab treatment. After treatment, the serum phosphorus level of all patients increased; the serum phosphorus of 3 children patients increased above the lower limit of the reference value range; the serum alkaline phosphatase(ALP) of all patients was lower than that of before treatment; the serum ALP of one adult patient was close to the normal range after 2.5 years of treatment. One child patient showed small crystals in kidney through ultrasound 48 weeks after treatment; one child and one adult showed increased serum parathyroid hormone(PTH)level before treatment and serum PTH continued increasing after treatment. Finally, it may be concluded that burosumab increased serum phosphorus levels in XLH patients, kept the level relatively stable, and reduced serum ALP levels. No serious adverse reactions occurred during treatment, in order to provide reference for the use of burosumab in patients with XLH.