BACKGROUND:The biomechanical effect of the implant-bone interface is one of the most important factors for bone resorption. The new structure of the periodontal-ligament-like implants may improve the distribution of the interfacial stress. OBJECTIVE:To discuss the effect of the internal structure changes of traditional implants on the cortical bone stress distribution and peak at the implant-bone interface under different occlusal load conditions, so as to provide a theoretical basis for the optimization design and clinical application of new structure implants. METHODS:Two kinds of digital models, new structure implant (model A) and non-threaded cylindrical implant (model B), were established by Pro/ENGINEER software. Variations of the stress peak and stress distribution of implant-bone interface cortical bone area under the same bone and force environment were analyzed using Ansys software. RESULTS AND CONCLUSION: Under a vertical loading, the stress peak under different forces was reduced by 17.54% in model A compared with model B; under a 45° loading, the stress peak of model A was reduced by 2.59% compared with model B, and it showed an evident tendency of high stress area focusing to the buccal side of model B. Under the chew-simulation loading, the stress peak of model A was lower than that of model B. The biggest difference (0.353 2 MPa) appeared atβ=12°(β is the angle of force direction and the implant axis), and it gradualy reduced atβ > 12°. At the same time, model A had a wider range of application degree compared with model B in two quantitative indicators, including optimal peak stress of promoting bone tissue growth and stress peak of maintaining healthy bone tissue. These results suggest that the optimized structure of implants contributes to improve the cortical bone stress distribution at the implant-bone interface, decrease the peak stress, and reduce the risk of cortical bone absorption in a wider range.

Animals ; Arterial Occlusive Diseases ; physiopathology ; therapy ; Dogs ; Genetic Therapy ; Hepatocyte Growth Factor ; genetics ; Hindlimb ; blood supply ; Ischemia ; physiopathology ; therapy ; Male ; Plasmids

BACKGROUND:Alogeneic bone marrow stromal stem cel transplantation for treatment of bone diseases is a hot topic. To seek effective methods for prevention of post-transplantation immune rejection is urgent to be solved.
OBJECTIVE:To explore the expression of MHC antigen on the surface of bone marrow stromal stem cels after osteogenic inductionin vitro.
METHODS:Bone marrow samples were extracted from rabbits to in vitro isolate and culture bone marrow stromal stem cels. Then, the cels were cultured in IMDM medium containing bone morphogenetic protein-2. Flow cytometry was used to analyze the expression of MHC antigen on the osteoblasts differentiated from bone marrow stromal stem cels.
RESULTS AND CONCLUSION:There was highly expressed MHC I antigen but no MHCII antigen on the osteoblasts differentiated from bone marrow stromal stem cels. After osteogenic induction, no immune rejection was found. These findings indicate that alogeneic or xenogeneic bone marrow stromal cel transplantation can be used in the treatment of bone defects.

BACKGROUND: Umbilical cord blood mesenchymal stem cells (UCB-MSCs) can differentiate into various types of cells under certain condisions, and easily proliferate in vitro. However, UCB-MSCs have long establishment time and low frequency.OBJECTIVE: To in vitro isolate and culture UCB-MSCs, and induce its differentiation into osteoblasts.DESIGN, TIM E AND SETTING: The in vitro cytological study was performed at the Laboratory of the Medical College of Qingdao University from June 2008 to January 2009.MATERIALS: UCB was obtained from term normal delivery women at the Department of Gynaecology and Obstetrics, Qingdao Municipal Hospital.METHODS: Human UCB-MSCs were isolated and cultured in vitro by Percoll density gradient. When reached 90% confluency,UCB-MSCs were digested by trypsin for subculture. At the third passage, UCB-MSCs at 1×106 were incubated. When reached 50% 60% cenfluency, UCB-MSCs were treated with DMEM supplemented with 0.1 μmol/L dexamathasone, 10 mmol/Lβ-sodium glycerophosphate and 50 μmol/L vitamin C. UCB-MSCs in the control group were incubated in low glucose DMEM.MAIN OUTCOME MEASURES: Growth and proliferation of MSCs were observed under the inverted microscope. Cell surface marker expression and cell growth curve were measured by flow cytometry. Cell ultrastructure was observed under the transmission electron microscope. Differentiation of UCB-MSCs into osteoblasts was determined by Won Kossa staining and alkaline phosphatase staining.RESULTS: Primary cultured UCB-MSCs had similar morphology to bone marrow mesenchymal stem cells. After passage, cell morphology was even, presenting spindle shape. UCB-MSCs at passage 3 highly expressed CD29, CD44, CD13, but did not express CD34. Growth latency was 2-3 days. Cells entered logarithm proliferation phase at days 3-4, and platform phase 1 month later. Nuclei presented round or irregular, with clear nuclear membrane, 1-2 nucleoli, rough chromatin, abundant organelles and microvilli. UCB-MSCs at passage 3 were gradually confluent following 3 days of osteogenic induction, with the presence of pavement-stone shape. 14 days later, calcified nodules by Von Kossa staining, and cells were positive for alkaline phosphatase staining. In the control group, no calcified nodules were found, and cells were negative for alkaline phosphatase staining.CONCLUSION: UCB-MSCs can be successfully isolated by Percoil density gradient, and induced to differentiate into osteoblasts in vitro.

Objective To evaluate the performance parameters of the PET instrument, which has been used for years in our hospital, assuring the stability of image quality and performance parameters. Methods NEMA NU 2-1994 Standards was used as reference for performance measurement of PET, which were published by National Electrical Manufacturers Association(NEMA). The NEMA standard cylinder model, 18F radiation source, and 18F and 68Ge columniform radiation source were used. Results Projects for performance measurement and daily quality control were drawn up. Conclusion This project provides a reference and methods for the performance measurement of PET instrument and daily quality control. It better ensures the stability of image quality and performance parameters of the PET instrument.

Objective:To investigate the role of bone morphogenetic protein 2/7 heterodimer (BMP-2/7)in the osteogenesis of human adipose-derived stem cells (hASCs).Methods:hASCs were exposed to three different treatments in vitro:osteogenic medium with 1 50 μg/L BMP-2/7 (experimental group), osteogenic medium alone (OM group)and proliferation medium (PM group).After 1 ,4 and 7 days of osteogenic induction,the amount of cellular DNA was measured to investigate the cytotoxicity.After 7 and 1 4 days,alkaline phosphatase (ALP)staining and quantification were performed to test the activity of ALP.After 21 and 28 days,the calcification deposition was determined by Alizarin Red S (ARS)stai-ning and quantification.The expressions of the osteoblast-related genes were tested on days 1 ,4,7 and 1 4.In the in vivo study,6 nude mice were used and 4 groups were set and implanted subcutaneously into the back of nude mice:(1 )β-TCP scaffold only (scaffold control group );(2 )β-TCP scaffold with hASCs cultured by PMin vitro for 1 week (PMcontrol group);(3)β-TCP scaffold with hASCs cultured by OM in vitro for 1 week (OM control group);(4)β-TCP scaffold with hASCs cultured by OM with 1 50 μg/L BMP-2/7 in vitro for 1 week (test group).After 4 weeks of implantation,histological staining was performed to evaluate the in vivo osteogenesis of hASCs.Results:After induction for 1 day,there was no significant difference between the experimental group and the PM group on the cellular DNA con-tent (P>0.05 ).After 4 days,the cellular DNA content increased under the stimulation of BMP-2/7 (P<0.05).On day 7,there was no significant difference among the three groups (P>0.05).ALP ac-tivity was higher by the induction of BMP-2/7 than in OMalone and PM(P<0.05).More mineraliza-tion deposition and more expressions of osteoblast-related genes such as Runx2,ALP,COL-1 A1 and OC were determined in the experimental group at different time points (P<0.05).HE staining showed that, in the test group and OM control group,the extracellular matrix (ECM)with eosinophilic staining were observed around hASCs,and newly-formed bone-like tissues could be found in ECM around the scaffold materials.Moreover,compared with the OM control group,more bone-like tissues could be observed in ECMwith typical structure of bone tissue in the test group.Masson’s trichrome staining showed that more expression of collagen could be observed in ECM in the test group compared with the other groups.There was small amount of expression of collagen in the OM and PM control groups.No obvious positive results were found in the scaffold group.Conclusion:BMP-2/7 heterodimer plays a significant role in the osteo-genesis of hASCs and is able to enhance the osteogenic differentiation of hASCs in vitro and in vivo.

Objective To evaluate the effect of transcatheter hepatic artery embolization with lipiodol on perfused radiofrequency ablation (PRFA) on mini-porcine.Methods Ten Chinese mini-porcine were randomly divided into embolization group and control group (each n=5) .A standard PRFA with infusing cooling procedure was done in control group,while transcatheter hepatic artery embolization with lipiodol was done before PRFA in embolization group.CT and MR scan were performed after PRFA.Then a comparative analysis of the shape and volume of the lesions in the liver were performed.Resuits In both two groups,distinct spherical margin of the PRFA lesions was obtained.The minimal diameter was (31.76±3.43) mm in embolization group and (27.23±3.49) mm in control group (t=2.675,P＜0.05) .The average volume of the embolization group was (54.47±9.98) cm~3,while in the control group was (20.90±5.68) cm~3 (t=10.424,P＜0.05) .Conclusion Transcatheter hepatic artery embolization with lipiodol before PRFA can enlarge the ablation size of mini-porcine's liver.

Objective:To identify the cerebral activation patterns associated with the processes that occur during viewing Chinese and English words in native Chinese English learners.Methods:12 right-handed Chinese English hamers were divided into two groups equally,namely English majors and non-English majors,and took semantic judgement tasks of both English and Chinese words,for whom the fMRI images were coUected.Results:To various degrees,all subjects demonstrated activation of associated cerebral regions in both hemispheres and the left hemisphere activation was more significant for most subjects.Except for elassieal regions involved in language processing,such as Wemicke areas and Broca areas,there were other activated cerebral regions,including cerebellum,limbic system and basal ganglia nucleus,etc.To sum up,there were apparent overlap for cerebral activation distribution and no specific processing areas for both tasks.The analysis of ROI(region of interest)suggested that subjects in specialized group were more dependent on right hemisphere to perform English words task.Conclus/on:Language cognition is dominated by left hemisphere,which is also shared by the right hemisphere to various degrees and thus two hemispheres work by ways of both dissociation and coordination.It is possible that working strategy of the right hemisphere in English task is related to proficiency of the second language.A variety of distinctions are shared by each subject for language cognitive patterns.

Objective To observe the effect of early rehabilitation treatment at different time point on the motor function and activity of daily living (ADL) and emotion in acute stroke patients. Methods 120 patients with acute stroke were randomly assigned to three reha-bilitation groups and one control group according to the disease course (3 days, 5 days, 8 days when the disease is steady). Each group con-sisted of 30 eases. The patients in each group were treated with the regular medication therapy, rehabilitation groups were treated with com-prehensive rehabilitation treatment including Bobath technique therapy. Neurological deficit, motor function, balance function, ADL, emo-tion of all the patients were assessed before and 21 days after rehabilitation intervention. Results After treatment, the motor function, bal-ance function, ADL and emotion of each rehabilitation group were improved. The patients'rehabilitation scores in FMA, Fugl-Meyer balance function, MBI and HRSD got much better than that in control group. The difference was statistic significant. The effect of rehabilitation treat-ment did not show difference among rehabilitation groups. Conclusion Early rehabilitation treatment for acute stroke does benefit for stroke patients. Effect does not show vary with the start time of rehabilitation treatment within 8 days after acute stroke.

Objective To investigate the underlying neural mechanism of left hemiparalexia and left hemialexia in reading Chinese characters. Methods A patient with reading disorders caused by brain infarctions at the left ventralis medialis occipitotemporal lobe and the splenium of the corpus callosum was studied. A series of neuropsychological tests, such as reading Chinese characters presented in the central foveal field or in the left and right half of the foveal field, were conducted with the patient, and neuroimaging techniques including high spatial resolution 3D-MRI and diffusion tensor tractography (DTT) were used to examine whether or not there were lesions of the neural pathway. Results The patient showed left hemiparalexia, which was characterized by making substitution or omission mistakes, mostly in the left parts of Chinese characters, and also left hemialexia(alexia for characters presented in left visual field). 3D-MRI demonstrated infarctions in the left ventral mesial occipitotemporal area and in the left side of the splenium of the corpus callosum. The left lateral mid-fusiform cortex, which has been identified as the visual word form area(VWFA), was almost intact. DTT indicated the major forceps fibers running through the splenium were all disconnected due to the infarction of the left splenium. Conclusion As a result of disruption of the splemium-major forceps pathway, visual character information in the left visual field which is initially projected to the right occipital cortex cannot be transferred from the right visual cortex to the left VWFA. This mechanism of left hemiparalexia and left hemialexia in reading Chinese characters is similar to that in reading English words.