BACKGROUND:Thrombus formation and neointimal hyperplasia still limit the use of small-caliber expanded poly(tetrafluoroethylene) (ePTFE) vascular prosthesis with a diameter less than 6 mm for revascularization in the coronary or peripheral circulation. Bioactive surface heparin coating is one conceivable path for above-mentioned problems.OBJECTIVE: To elevate the anticoagulant property of ePTFE, this study promoted the patency of a novel small-caliber ePTFE vascular graft by modifying its luminal surface with covalently crosslinked poly(vinyl alcohol)/ p-diazonium diphenyl amine polymer/heparin gel (PVA/PA/Hep gel) and examined the hemocompatibility of the graft.DESIGN, TIME AND SETTING: Observational experiments were performed at the Nanomedicine and Biosensor Lab,Biomedical Engineering Center, Harbin Institute of Technology from May 2006 to June 2007.MATERIALS: The ePTFE vascular grafts (diameter of 4 mm), Nafion (Naf) and Poly(vinyl alcohol) (Aldrich, USA), heparin (Mw 12 000- 14 000) (Calbiochem, USA), p-diazonium diphenyl amine polymer (PA) (this lab, China) were used in this study.METHODS: ①The vascular graft surface was firstly modified with Nafion. ②Following the impregnation of the mixture of PVA/PA/Hep, covalent crosslinking between polyvinyl alcohol and heparin was performed using crosslinker PA under ultraviolet radiation.MAIN OUTCOME MEASURES: ①Contact angles, ②Attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR), ③Activated partial thromboplastin time (APTT) and prothromhin time (PT), ④hemolysis test, ⑤platelet adhesion test and ⑥thrombosin inactivation test.RESULTS: ①The water contact angle of the vascular graft surface was greatly decreased after modifying. ATR-FTIR revealed the disappearance of diazonium groups at 2 172 cm-1 and 2 224 cm-1. Vascular prosthesis after modifying had prolonged APTT and PT, low percent hemolysis and low amount of platelet adhesion. Modified vascular prosthesis had inhibitory effect on thrombosin activity and good coating stability.CONCLUSION: Converage of PVA/PA/Hep has good antithrombotic function and low percent hemolysis, resulting in improving hemocompatibility of vascular prosthesis.

BACKGROUND: For decades, liposome drug carrier has been used to enhance drug stability and efficacy, reduce drug toxicity and adverse effects. However, they fail to provide long-term delivery due to insufficient stability. Studies have demonstrated that silica is not toxic, with chemically inert and biological compatibility, and can be used as modified material. OBJECTIVE: To characterize the silica coated liposome and investigate the controlled release property. DESIGN, TIME AND SETTING: In vitro observation. The study was performed at the Nanomedicine and Biosensor Laboratory, Biomedical Engineering Center, Harbin Institute of Technology from May 2007 to June 2008. MATERIALS: Dipalmitoylphosphatidylcholine (DPPC) was purchased from Nanjing Kangsente Chemical Engineering Company; tetraethylorthosilicate (TEOS) was purchased from Aldrich, USA. Doxorubicin (DOX) was purchased from Beijing Huafeng United Technology Company; Sephadex G-50 was purchased from Amersham Biosciences, Sweden. All other chemical agents were of analytical purity. METHODS: Liposome was formed from DPPC following the precipitation of silica by sol-gel method. MAIN OUTCOME MEASURES: Zeta-potential and dynamic light scanning were used for zeta-potential measurement and particle size distribution; transmission electron microscopy was used to collect the image of particle morphology; Fourier transform infrared spectroscopy (FTIR) was used to display chemical characteristics of Si-O-Si structure; Spectrophotofluorimetry was used to determine DOX regression equation and was further used for calculation in drug encapsulation efficiency and in vitro release.　RESULTS: ①Silica coated liposome was successfully prepared. ②FTIR proofed the presence of Si-O-Si at 1 166, 1 080, 859 and 526 cm-1. ③The DOX encapsulated silica coated liposome had encapsulation efficiency of 72.4%. ④Drug release profiles showed that sustained release of DOX was achieved after modification of silica on liposome. CONCLUSION: With Si-O-Si as protective layer, the liposome has increased stability and prolonged drug release.

BACKGROUND: The expanded polytetrafluoroethylene (ePTFE) vascular grafts hold promise for enhanced healing,extended suture retention, kink reduction and compression resistance. But thrombus formation still limits its use for revascularization of small-caliber vessels. It is the surface of ePTFE vascular graft that contacts with the blood. The current study focused on surface modification of ePTFE materials to improve its blood compatibility.OBJECTIVE: To characterize the heparin/alginate (H/A) gel modified ePTFE vascular graft and investigate the hemocompatibility and histocompatibility of the graft.DESIGN: Observation experiment.SETTING: Laboratory for Nanomedicine and Biosensor, Biomedicine Engineering Center, Harbin Institute of Technology.MATERIALS: The GORE-TEX ePTFE vascular grafts were 4 mm in internal diameter. Sodium alginate and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) were purchased from Sigma. Heparin sodium salt was obtained from Calbiochem. Nation and chitosan were purchased from Aldrich company. Human α-thrombin and AT Ⅲ were purchased from Haematologic Technologies, Inc. S-2238 was purchased from Chromogenix.METHODS: This study was performed at the Laboratory for Nanomedicine and Biosensor, Biomedicine Engineering Center, Harbin Institute of Technology between May 2006 and June 2007. The graft was first modified with Nation and then Chitosan/Nafion/Chitosan multilayer. Following the impregnation of heparin and alginate, covalent crosslinking was performed using ethylenediamine and EDC. Some characterization methods were employed: stastic water contact angle for the hydrophilicity; SEM for the surface morphology; ATR-FTIR for the surface chemical characteristics; APTT and PT,percent hemolysis and Chromogenic assay for the hemocompatibility of the ePTFE vascular graft after modification.MAIN OUTCOME MEASURES: ①Static water contact angles. ②Charactedzation of the surface morphology and platelet adhesion by SEM. ③ATR-FTIR ④APTT and PT. ⑤Percent hemolysis ⑥Chromogenic assay for heparin activity.RESULTS: ①ATR-FTIR revealed the presence of -CO-NH- at 1626 cm-1. ②The water contact angle was greatly decreased from (125±1)° to (84±2)° .③The prolonged APTT and PT, low percent hemolysis(0.065%) and low amount of platelet adhesion assay showed the H/A gel impregnated graft had good blood compatibility. ④Chromogenic assay showed the modified graft was less thrombogenic than the bare one, and the H/A coating had good stability in. PBS buffer.CONCLUSION: The H/A modified ePTFE vascular graft has great potential in applications utilizing small-diameter vascular grafts.

Objective To manufacture magnetic microbubbles with dual-response to ultrasound and magnetic fields.Methods Microbubbles of ultrasound contrast agent (ST68) based on a surfactant were prepared by the acoustic cavitation method.Fe3O4 magnetic nanoparticles with negative charge were synthesized using the polyol procedure.Magnetic microbubbles were generated by depositing polyethylenimine and Fe3O4 magnetic nanoparticles alternately onto the microbubbles using the layer-by-layer self-assembly.In vitro ultrasonography was performed on a silicone tube with/without magnetic microbubbles (3 × 108/ml) by a self-made device to observe the movement of magnetic microbubbles under the effects of magnetic field.In vivo imaging was performed on the kidney of New Zealand rabbits before and after the injection of magnetic microbubbles.Results The Fe3O4 nanoparticles carried a stable negative charge of (-24.6 ± 6.7) mV and more than 98％ of the particles were less than 8 μm in diameter,meeting the size requirement of an ultrasound contrast agent for intravenous administration.There was no echoic signal in the silicone tube before injection of magnetic microbubbles,but there were strong echoic signals after injection.After applying a magnetic field,the magnetic microbubbles moved along the direction of the magnetic flux.In vivo ultrasound imaging could not visualize the kidney before injection of magnetic microbubbles,but could remarkably visualize the kidney after injection.Conclusions The magnetic microbubbles exhibit favorable magnetic targeting and ultrasound contrast enhancement characteristics.Such properties may serve as the foundation to study their potential for simultaneous diagnosis and treatment in the future.

Objective To fabricate an ultrasound/fluorescence bi-modal contrast agent by encapsulating fluorescent quantum dots into polymeric ultrasound contrast agent microbubbles.Methods Polylactic acid (PLA,500 mg),(1R)-(+)-camphor (50 mg) and CdSe/ZnS quantum dots (0.5 ml,2.3 μmol/L)were dissolved or dispersed in dichloromethane (10 ml) to form in an organic phase.Ammonium carbonate solution and poly (vinyl alcohol) solution were employed as the internal and external water phase,respectively.The fluorescent microbubbles were generated using double emulsion solvent evaporation and lyophilization methods.The morphology and illumination were characterized by scanning electron microscopy (SEM) and fluorescence spectrophotometry.Synchronized contrast-enhanced ultrasound and fluorescence imaging was acquired by injecting fluorescent microbubbles into the silicone tube coupled to a self-made ultrasound/fluorescence imaging device.Ultrasound/fluorescence bi-modal in vivo imaging was acquired on the kidney of New Zealand rabbits and suckling mice.Results The fluorescent microbubbles were hollow spheres with an averaged diameter of (1.62 ± 1.47) μm.More than 99％ of these microbubbles were less than 8 μm in diameter,which meeted the size criteria for ultrasound contrast agents.The fluorescence emission peak of the microbubbles appeared at 632 nm,indicating that good luminescence properties of quantum dots were maintained.In vitro ultrasound/fluorescence imaging showed no echoic signal when the silicone tube was filled with saline,but there was a strong echo when filled with fluorescent microbubbles.The liquid column with fluorescent microbubbles emitted red luminescence under ultraviolet irradiation.The kidney of the rabbit was remarkably enhanced after the administration of fluorescent microbubbles.Bright fluorescence could be observed at the injection site of the suckling mice via subcutaneous injection.Conclusions A bi-modal but single contrast agent based on polymeric microbubbles has been successfully fabricated for the use of ultrasound and fluorescence imaging.It retains the good characteristics of both echogenicity and fluorescence,which complement each other in case of limitations imposed by uni-modal,single agents.

Objective To compare the effects of repetitive transcranial magnetic stimulation (rTMS) at various low frequencies on upper limb function after cerebral infarction.Methods Fifty patients were randomly assigned to a control group (10 cases),a sham rTMS group (10 cases) or an rTMS group which had three sub-groups treated at 0.25 Hz,0.5 Hz and 0.75 Hz with 10 cases in each.All of the patients were treated with conventional medical treatment and rehabilitation training.The sham and true rTMS groups received rTMS applied over the M1 area of the unaffected hemisphere,5 days per week for 4 weeks.Motor evoked potential (MEP) cortical latency,and central motor conduction time (CMCT) were measured and the Fugl-Meyer assessment (FMA),motricity index (MI) and a Hong Kong functional test for the hemiplegic upper extremity (FTHUE-HK) were evaluated beforehand and at Post 1 after 2 weeks of treatment and Post 2 after 4 weeks of treatment.Results The average CMCT and FMA scores of the control and sham rTMS groups both had improved significantly at Post 2.There was no significant difference in any of the indices between those 2 groups at any time point.At Post 1,the average MEP cortical latencies of the 0.25 Hz and 0.5 Hz subgroups had improved to be significantly better than those of the control and sham rTMS groups.The average CMCTs of the 0.25 Hz and 0.5 Hz rTMS subgroups were significantly shorter after treatment,and significantly better than those of the control and sham rTMS groups.At Post 2,the average MEP cortical latency of all groups except the control group showed significant improvement compared with pre-treatment.The 2 indices of the 0.25 Hz and 0.5 Hz subgroups were again significantly shorter than those of the control and sham rTMS groups,and the average CMCTs were significantly better than that of 0.75 Hz subgroup.At Post 1 the average FMA and MI scores of the rTMS subgroups had all improved significantly.In the 0.25 Hz and 0.5 Hz subgroups the average MI scores were significantly higher than those of the control and sham rTMS groups.The FTHUE-HK scores of those 2 subgroups had also improved significantly.At Post 2,the average FMA and MI scores of all groups and the FTHUE-HK scores of rTMS group had improved significantly.In the 0.25 Hz and 0.5 Hz subgroups,all of the indices were significantly better than in the control and sham rTMS groups.The average FTHUE-HK score of the 0.25 Hz subgroup was significantly superior to that of the 0.75 Hz subgroup.In the 0.75 Hz subgroup the average MI score was significantly higher than in the control and sham rTMS groups.Conclusions rTMS at either 0.25 Hz or 0.5 Hz applied to the unaffected hemisphere provides effective treatment for enhancing the excitability of the motor cortex and the motor function of a paretic upper limb after stroke.Compared with others,the total number of stimulus pulse in 0.25 Hz subgroup was the least,and priority consideration should be given to the frequency of 0.25 Hz when using rTMS in clinical treatment of cerebral infarction.

Objective:To investigate the clinicopathologic features and molecular genetics characteristics of sinonasal tract mucosal malignant melanomas(STMMMs)in elderly patients.Methods:The clinicopathological features, immunohistochemical features and BRAF, C-KIT, NRAS mutations of STMMM in ten elderly patients were retrospectively analyzed.Results:Among the 10 patients, 5 were female and 5 were male.The patients were aged 65-81 years, with an average age of(72.5 ± 8.5)years.The lesions in 7 cases were located in the nasal cavity and paranasal sinuses, and in the other 3 cases were located in the nasopharynx.The morphologies of tumor cells under microscope was complex and diverse, showing plasma cell-like, rhabdomyoblast-like, small cell-like, epithelial-like, and spindle cell-like morphologies.Immunohistochemically, HMB-45 and S-100 were generally positive in 10 cases, and the positive rate of Melan A was 70.0%.The genes detection data showed no mutations in BRAF or NRAS genes in all the 10 cases, while C-KIT exon 11 c. 1666_1667insA mutation was found in one case, and the remaining 9 cases were wild-type for C-KIT.All the 10 cases were followed up for 4~50 months.Three cases survived so far.Conclusions:STMMM in elderly patients are rare and easy to be misdiagnosed.Immunohistochemistry and genetic testing provide guidance for accurate diagnosis and targeted therapy.