BACKGROUND: Tooth intrusion easily leads to root resorption. Previous studies regarding orthodontic treatment-caused tooth root resorption or retrospective clinical studies based on X-ray films have great errors in outcome evaluation because of intrusion force which cannot be precisely controlled. OBJECTIVE: This study established dog models of mini-implant anchorage for incisor intrusion to observe the histological changes of tooth root and periodontal tissue and to evaluate the feasibility and safety of mini-implant anchorage for incisor intrusion. METHODS: Nine dogs were assigned to one control group (n = 1) and four experimental groups per time to sacrifice (1, 2, 4 and 12 weeks; n = 2 dogs for each experimental group). No force was added to the control group. In the experimental groups, mini-implant as an anchorage was placed in the buccal alveoli between maxillary second and third incisors on each side. A traction force of 100 g was imposed to each side to intrude the maxillary first and second incisors on each side. At 1, 2, 3, and 4 weeks (traction force was imposed for 4 weeks and after withdrawal of extraction force, mini-implant was retained in place for 8 weeks), dogs were sacrificed. The first and second incisors together with gingival and alveolar bone were completely resected to prepare histological specimens. Following hematoxylin-eosin staining, histological changes of tooth root and periodontal tissue were observed. RESULTS AND CONCLUSION: Compared with the control group, in the 1-week group, histological changes were primarily at the root tip and alveolar ridge crest, alveolar bone and cementum were absorbed and peridental membrane presented glassy degeneration in local region; in the 2-week group, bone resorption degree and range were obviously enlarged, and bone resorption developed from root tip, root middle part to cervical part; in the 4-week group, bone resorption was still active and the glassy degeneration of peridental membrane disappeared; in the 12-week group, significant improvement in alveolar bone and cemental surface was observed, bone lacuna had deposition of newly formed bone, and peridental membrane was orderly arranged. These findings reveal that in the mini-implant anchorage for dog incisor intrusion, early histological changes primarily appear in the root tip and alveolar ridge crest, presenting as alveolar bone and cemental resorption and the glassy degeneration of the peridental membrane. Bone resorption extent and range expand with the persistence of traction force. After withdrawal of traction force, tooth root and periodontal tissue were gradually repaired

Objective To investigate the effects of Erigeron breviscapus Hand Mazz(EBH) on learning and memory dysfunction in mice with cerebral ischemia/reperfusion injury.Methods 40 mice were randomly divided into control group, sham operated group, model group and EBH group, with 10 mice each. Mice model of cerebral ischemia/reperfusion injury was established by bilateral common carotid artery blocking. 7 days before and after operation, the mice in EBH group were injected I.p.with EBH injection 0.15 ml/d, while those in other groups were injected I.p. with saline 0.15 ml/d. The learning and memory function was tested by Morris water maze.Results The latent period in the model group was longer than that in the normal group and the sham operated group (P<0.05). EBH could shorten the latent period significantly as compared with those in the model group (P<0.05).Conclusion EBH can improve learning and memory function in cerebral ischemia/reperfusion injured mice.

ObjectiveTo investigate the effects of Aniracetam on learning and memory dysfunction in mice with cerebral ischemia/reperfusion injury. Methods48 mice were randomly divided into control group, sham operated group, model group and Aniracetam group, with 12 mice each. Mice model of cerebral ischemia/reperfusion injury was established by bilateral common carotid artery blocking. The learning and memory function was tested by Morris water maze.ResultsThe latent period in the model group was longer than that in the normal group and the sham operated group (P<0.05). Aniracetam could shorten the latent period significantly as compared with those in the model group (P<0.05). ConclusionAniracetam has effects in improving learning and memory function in cerebral ischemia/reperfusion injured mice.

In order to observe the replication and expression of HGV RNA genome in HepG2 cells and establish a cell model of HGV infection, HGV RNA genome was prepared in vitro and transfected HepG2 cells with lipofec-tamin. HGV RNA-positive supernatants were used to infect fresh HepG2 cells. RT-PCR, immunohistochemistry and Western blot assays were carried out to detect the replication and expression of HGV in HepG2 cells. Both positive and negative strands of HGV RNA could be detectable in cell culture supernatants and cells at 24h post-transfection. During the culture periods of 90 days, the cells were maintained by changing the medium every 3 or 5 days, and cultured for more than 20 passages. Both strands of HGV could be detectable in culture supernatants and cells. Immunohistochemistry and Western blot results also confirmed that HGV E2 protein could be expressed in the infected HepG2 cells. HGV RNA could also be detectable in the frozen-thawed HepG2 cells infected with HGV RNA genome. Therefore, HGV RNA genome can replicate and express in HepG2 cells, this HGV RNA genome transfected cells model could be used as a cell model in the studies of replication and infection of HGV.

Objective To explore the application of low dose of radiation combined with low concentration of contrast medium in the energy spectrum CT of the coronary artery angiography.Methods 60 patients with suspected diagnosis of coronary heart disease were randomly divided into A,B two groups,30 cases in each group.Group A with 350 mg I/mL contrast agent,undergoing conventional CT scanning;Group B using 300 mg I/mL contrast agent,the gems energy spectrum CT scanning with low-dose.Two groups both adopted forward-looking heart switch control scanning mode.After scanning,group A reconstructed conventional images of 40% ASiR sequence,group B rebuilded axial surface images of single energy 65 keV and 40% ASiR sequence,all the reconstruction images were introduced to AW4.6 workstations used for analysis.Double-blind subjective rating was done by two experienced doctors to measure CT values and SD of aortic sinus (AS),left main (LMA),the left anterior descending branch proximal (LAD-p),left circumflex branch proximal (LCX-p), right coronary artery proximal (RCA-p)and pericardial fat,AS the noise (SD),to calculate the signal-to-noise ratio (SNR)and contrast to noise ratio (CNR),to calculate the effective doses of radiation(ED)by recording CTDI and DLP,and to record iodine intake.By using two independent samples t test to compare two groups of patients’the effective radiation doses,iodine intake,the average CT value,SD,SNR and CNR.Results The subjective image quality score differences and coronary measuring section CT values between the two groups had no statistical significance.In the aspects of effective radiation dose,group B reduced about 29% compared to group A,the difference was statistically significant.Iodine intake in group B decreased about 16% than in group A.Conclusion In coronary artery CT imaging, spectral scanning with low dose of radiation and reconstruction images with single energy can effectively reduce the radiation dose and iodine intake,at the same time it can obtain the approximate image quality like conventional scanning.

ObjectiveTo investigate the effects of 1-3-n-Butylphthalide on the blood-brain barrier (BBB) following whole brain irradiation in rats.Methods144 male Sprague Dawley rats were randomly divided into sham-irradiation group,irradiation group,1-3-n-Butylphthalide group,and irradiation plus 1-3-n-Butylphthalide group.Whole-brain irradiation was given as a single-dose of 10 Gy using 4 MV X-ray.The rats were injected intraperitoneally with 1-3-n-Butylphthalide at 0.3 mg/kg,1.0 mg/kg,3.0 mg/kg once per day.The changes of the BBB were assessed by Evans blue (EB) assay.The expression of vascular endothelial growth factor (VEGF) in the brain tissue was determined by immunohistochemistry. The circulating endothelial cells (CECs) isolated from right ventricular blood were counted.MRI was evaluated with the T1-weighted images,T2-weighted images and MRI enhancement images induced by Gd-DTPA.The data were compared among the groups through Student-Newman-Keuls test.ResultsCompared with the sham-irradiation group,the EB content,the expression of VEGF in the brain tissue and the CECs were significantly increased in the irradiation group (2.81∶ 7.82,P =0.002;5.83∶ 10.26,P=0.003;3.16∶6.14,P =0.002).The signal intensity of T1-weighted images was significantly decreased while T2-weighted images and the enhancement rate significantly increased in the irradiation group (P =0.004 -0.018 ).Compared with irradiation group,the EB content,the expression of VEGF and the CECs were decreased significantly in the irradiation plus 1-3-n-Butylphthalide group ( 7.80∶ 3.86,P =0.007 ; 10.83 ∶ 5.26,P =0.008 ;6.36∶ 3.64,P =0.009 ).However,the changes in the MRI were significantly attenuated ( P =0.008-0.026,and 0.006 -0.038,respectively).Conclusions Following whole brain irradiation,1-3-n-Butylphthalide can decrease the permeability of the BBB in rats via decreasing VEGF expression and decreasing the CECs.

Objective To assess the clinical value of three dimensional dynamic contrast enhanced MR angiography (3D DCE MRA) in the detection for intracranial aneurysm. Methods 3D DCE MRA was performed in 54 patients highly suspected with intracranial aneurysms. Then conventional digital subtraction angiography (DSA) and feasible endovascular treatment were performed simultaneously. A three dimensional fast imaging with steady state precession (3D FISP) was used for 3D DCE MRA(Gd DTPA dose, 0.2 mmol per kilogram for body weight; acquisition time, 10 seconds). The source images were subtracted from mask images and transferred to computer workstation. All images were subsequently post processed using three dimensional reconstruction. 3D DCE MRA images and DSA images were compared for demonstration of the aneurysm, its neck, and relationship with parent artery, and the usefulness for endovascular treatment was evaluated. Results There were 39 cases with 45 intracranial aneurysms. The sensitivity, specificity, and accuracy of 3D DCE MRA were 96%, 73%, and 90%, respectively. Aneurysm and its neck depiction at 3D DCE MRA was significantly better than that at DSA, especially for aneurysms adjacent to the cavernous sinus and near the PICA of vertebral artery. 3D DCE MRA could guide neurosurgeons to the desired DSA projection, and helped them make plan for interventional or surgical treatment in advance. But the diagnosis should be very carefully made for small aneurysms located in the periphery and the arterial bifurcation. Conclusion 3D DCE MRA is a fast, noninvasive and efficient technique for diagnosing intracranial aneurysms. Its three dimensional information is helpful for DSA demonstration and treatment planning. Any uncertain diagnosis requires DSA confirmation.

Objective: To establish a curve of dosage gradient-liver signal intensity of superparamagnetic iron oxide (SPIO) in normal rats and to find an appropriate dose for enhancement. Methods: Seventy-two SD rats, 4 rats a group at random, underwent MR enhancement with 0, 2, 5, 8, 10, 12, 15, 20, 30, 40, 50, 60, 70, 80, 100, 140, 210, 280 μmol/kg SPIO respectively after plane examination. The signal-to-noise ratio of liver was measured and a curve of dosage gradient-liver signal intensity was made. Results: (1)With the increase of SPIO dose, the signal intensity of both T1 and T2 weighted images of liver declined. (2)T2 weighted images was more sensitive than T1 weighted images in small dose, the ED50 of T1 weighted was 8 μmol/kg, and the ED50 of T2 weighted was 5 μmol/kg. (3)When the dose was greater than 15 μmol/kg, the signal intensity of T1 weighted images declined more rapidly than T2 weighted, the effect of enhanced T1 weighted images resembled T2 weighted ones, and its images was with more fine resolution. (4)At the dose of 40 μmol/kg, the signal intensity of T1 weighted images approached the background noise, and at the dose of 15 μmol/kg, the signal intensity of T2 weighted images approached the background noise. Conclusion: Good effect of T1 and T2 enhanced MR imaging can be acquired at the dose of 20-10 μmol/kg SPIO respectively, the best contrast-to-noise ratio is found on T2 weighted enhanced MR image.

Objective To evaluate the clinical value of three-dimensional contrast-enhanced MR angiography (3D CE-MRA) in the diagnosis and treatment of visceral artery aneurysms. Methods Forty-three patients with visceral artery aneurysms underwent 3D CE-MRA sequence after injection of 0. 2 mmol Gd-DTPA per kg. bw. The source images were subtracted and transferred to computer workstation subsequently post-procession. Digital subtraction angiography (DSA) was performed in 19 patients simultaneously for the purpose of control study. Results There were 43 cases with 50 visceral artery aneurysms. The arteries involved were 32 splenic artery aneurysms accounting for 64% including 5 anomalously arising from superior mesenteric artery; 7 of superior mesenteric ( 14% ) ; 4 celiac ( 1 from celiomesenteric trunk), 5 of renal and 2 of hepatic. 3D CE-MRA clearly demonstrated aneurysm's location, size, morphology, and was superior to DSA in three-dimensional display of aneurysrn and its relationship with surrounding vessels and involved organs. Endovascular treatment was performed in 15 patients, surgical treatment in 9, and conservative therapy only in 19. Conclusion 3D CE-MRA is a noninvasive and accurate technique for the diagnosis of visceral artery aneurysms. Its three-dimensional anatomic information is very helpful for treatment planning. 3D CE-MRA could be used as a test of choice in the evaluation of visceral artery aneurysms.

Objective To explore the remodeling modes and the plaque distribution of atherosclerotic BA at 3.0T high resolution MRI.Methods 90 symptomatic patients with atherosclerotic stenosis of BA on digital subtraction angiography (DSA) (50 ％-99 ％) were recruited consecutively.Luminal area,vessel area of maximal narrow sites and the reference sites were measured.The differences of involved imaging parameters between negative group and positive group were analyzed.Results 51 patients with required imaging quality were enrolled finally.Among the 51 patients,the rate of positive remodeling cases was 72.5％ (37/51) and negative remodeling took over 27.5％ (14/51).Compared with the negative remodeling group,the positive remodeling group had greater plaque size,larger plaque burden percentage,and higher maximal wall thickness at maximal lumen narrowing sites.The plaques were mainly located at ventral wall of the vessel.Conclusion 3.0T high-resolution MR imaging could be applied in assessing the remodeling modes and plaque distribution of BA stenosis.