OBJECTIVETo modify biomacromolecules, such as chitosan and collagen, to synthesize a mineralized template that will induce self-growing remineralization of tooth enamel.

METHODSNatural polycation polysaccharide chitosan was modified through phosphorylation to synthesize the polyanion derivative ofphosphorylated chitosan. Parent hydrogels com- bined with chitosan and collagen I were built through peptide binding reaction using genipin as a crosslinker. The gels self- assembled on the tooth's inert surface, which was stimulated by ultraviolet radiation. The bionic saliva provided mineralized ion, and then the hydroxyapatite assembled and grew in situ on the tooth.

RESULTSThe functional group P04(3-) (3,446 cm(-1)) was grafted on chitosan as confirmed by the Fourier transform infrared spectroscopy. The porous polyelectrolyte complex hydrogel formed by the interaction between the polycation chitosan and the polyanion phosphorylated chitosan could induce hydroxyapatite crystal nucleation and growth on the hydrogel fiber surfaces. The neonatal crystal was hydroxyapatite as confirmed by X-ray diffraction and was tightly connected to the tooth. A continuous structure of column crystals with sizes ranging from 30 nm to 60 nm was observed. The structure was in parallel direction similar to the direction of the enamel rod, and its hardness was close to dentin.

CONCLUSIONThe parent hydrogels that were easily obtained and controlled could mimic the template of the enamel mineralization and induce a self-growing hydroxyapatite, which is an important step in the structural bionics of enamel.

Biocompatible Materials ; Chitosan ; Collagen ; Dental Enamel ; Durapatite ; Microscopy, Electron, Scanning ; Polymers ; Spectroscopy, Fourier Transform Infrared ; Tooth ; Tooth Remineralization ; Ultraviolet Rays ; X-Ray Diffraction

Objective To investigate the influences of sodium salicylate on the auditory brainstem response (ABR)and expression of EphA4mRNA in rat inferior colliculus and its effects on salicylate ototoxicity.Methods A total of 30 healthy SPF rats were randomly divided into five groups:the control group (without any treatment),S7 (i.m.injection of sodium salicylate,175mg/kg,twice daily for 7 days),S14(the same method as S7,twice daily for 14 days),S14+R14(the same method as S14,twice daily for 14 days and recovered for 14 days),and S14+R28(the same method as S14,twice daily for 14 days and recovered for 28 days).After the ABR assessment,rats were sacri-ficed after deep anesthesia and the inferior colliculus tissues were dissected.Real-time PCR was used to detect the expression of EphA4mRNA.Results Compared with the control group,ABR thresholds in the S7 group and S14 group were increased significantly (P<0.05),while there was no significant difference between the control group and the S14+R28 group (P>0.05).The inferior colliculus EphA4mRNA expression level of S7 group was signifi-cantly decreased than the control group (P<0.05).The EphA4mRNA expression level of S7 group was significant-ly decreased than the control group (P<0.05),while there was no significantly difference between the control group and the S14+R28 group (P>0.05).Conclusion Long term injection of sodium salicylate can cause changes in the inferior colliculus of EphA4mRNA which are related closely with synaptic plasticity.It may lead the alteration of the inferior colliculus synaptic plasticity,which is associated with the changes of the hearing failure and the tinni-tus behavior.This indicates that EphA4 which is considered as a related protein in the inferior colliculus may play an important role in the pathology of tinnitus.

Objective To explore the relationship between the expression of CD44v6,P16 protein and the invasion and metastasis in gastric carcinoma and to investigate the correlation between the expression of CD44v6 and P16 protein.Methods Immunohistochemical methods were used to detect the expression of CD44v6 and P16 protein in 110 cases of gastric carcinoma.Results In 110 cases of gastric carcinoma,the expression of CD44v6 and P16 protein were 72.7%(80/110)and 47.3%(52/110)respectively. The high level expression of CD44v6 protein and low level expression of P16 protein were positively correlated with the TNM staging,serosa infiltration,lympho node and liver metastasis of gastric carcinoma(P

Objective To investigate the prevalence of the occupational hazard of organic solvent and noise in printing and Methods record medium production enterprises in Longgang District of Shenzhen City. A total of 56 printing and record medium production enterprises were selected as the study subjects by judgmental sampling method to analyze the worksite Results survey of occupational health and the key occupational hazard factors. There were 256 organic solvent samples ， detected in 56 enterprises which included a total of 148 terms and 1 358 categories of volatile constituents. The top three （ ）， - （ ） （ ） volatile constituents were toluene 35.5% n hexane 25.7% and methanol 23.8% . The top three detected samples of the （ ， ， ， ， - ， ，- ， eight key chemical occupational hazard factors benzene toluene xylene ethylbenzene n hexane 1 2 dichloroethane ） ， - ， trichloroethylene and chloroform were toluene n hexane and ethylbenzene. In the workplace air toluene was the most risk ， factor of occupational hazard factors in enterprise and in sample detection while no trichloromethane was detected. The toluene in workplace air was found to exceed the national standard with the rate of 2.6%. It showed that 27.9% of the work sites were found occupational noise hazard which was over national standard in the 10 key work sites. Only 64.3% and 57.1% enterprises - performed occupational hazard factors detection and occupational health examination. Both none or invalid toxicant proof - facilities accounted for 33.9% of the enterprises. Both none or invalid noise proof facilities accounted for 78.6% of the Conclusion ， - enterprises. The occupational hazards factor of toluene n hexane and noise were serious in printing and record ， medium production enterprises in Longgang District of Shenzhen City and the occupational health management was imperfect. The occupational regulation should be enhanced in this industry.

In an anti-thrombotic pressure circulatory device, relays and solenoid valves serve as core execution units. Thus the therapeutic efficacy and patient safety of the device will directly depend on their performance. A new type of testing system for relays and solenoid valves used in the anti-thrombotic device has been developed, which can test action response time and fatigue performance of relay and solenoid valve. PC, data acquisition card and test platform are used in this testing system based on human-computer interaction testing modules. The testing objectives are realized by using the virtual instrument technology, the high-speed data acquisition technology and reasonable software design. The two sets of the system made by relay and solenoid valve are tested. The results proved the universality and reliability of the testing system so that these relays and solenoid valves could be accurately used in the antithrombotic pressure circulatory equipment. The newly-developed testing system has a bright future in the aspects of promotion and application prospect.
Equipment Design ; Humans ; Monitoring, Ambulatory ; instrumentation ; Pressure ; Reproducibility of Results ; Software ; Thrombosis ; diagnosis

The effects of C1-930, a known selective phosphodiesterase 111 inhibitor, on vascular resistance and rat aortic strip contraction were studied CI-930 025mg/kg injected into the perfused artery, reduced vascular resistance markedly in femoral artery and internal carotid artery in anaesthetized rats. The action lasted for about 15-20 min. CI-930 in vitro inhibited norepinephrine (NE) and TXA2/PGH, mimetic U-46619 induced rat aortic strip contraction significantly with PD, values of 6.71 and 5.5 respectively. The inhibitory effects of CI-930 on NE and U-46619 induced contraction were more potent than that of KG induced contraction. CI-930 0.01 - 10?mol/L exhibited a potential inhibitory effects on intracellular Ca2+ dependent contraction of rat aortic strip induced by NE, but had no effect on extracellular Ca2+ dependent contraction. The results suggest that CI-930 can possess a potent intracellular Ca2+ dependent vasodilating effects in vitro and in vivo.

Objective To evaluate the effect of Ebselen on the ischemia-reperfusion injury (IRI) in rat lungs from non-heart-beating donors (NHBD).Methods Forty Sprague-Dawley rats were paired randomly divided into two groups:group Ⅰ,NHBD with 30 min of warm ischemia time (WIT); group Ⅱ,NHBD with 30 min of WIT and administration of Ebselen.The donor lungs remained ventilated at the room temperature for 30 min after asystolia and then flushed with LPD solution.The recipient rats underwent left lung transplantation.The recipients of group Ⅱ were administered with Ebselen (500 mg/kg body weight) one h before transplantation.Results All the recipients survived during the observation period.In the group Ⅱ,the MDA of the pulmonary tissue was 0.631 ± 0.23 nrmol/mg protein,and the polymorphonuclear neutrophils and the total protein of the bronchoalveolar lavage fluid were (78.4 ± 35.2) × 107/L and (0.41 ± 0.12) mg/ml respectively.The MPO was (25.09 ± 1.19) ％ and W/D was 0.359 ± 0.017.There was significant difference between group Ⅱ and group Ⅰ (all P＜ 0.05).Conclusion The administration of ebselen is an effective treatment to attenuate the acute injury resulted from the ischermia-reperfusion in the rat lungs from non-heart-beating donors.

Adolescent ; Bone Neoplasms ; metabolism ; pathology ; surgery ; Diagnosis, Differential ; Follow-Up Studies ; Glomus Tumor ; metabolism ; pathology ; surgery ; Humans ; Immunohistochemistry ; Male ; Melanoma ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Tibia ; metabolism ; pathology ; surgery ; Vimentin ; metabolism

Objective To observe the expression of the IGF-1 on the auditory cortex as well as the hippo-campus of rats which underwent longterm exposure to white noise to explore its effects for the repairment of the noise induced damage in the central nervous system.Methods 16 healthy Wistar rats were randomly grouped as chronic noise exposure group(group A)which underwent the longterm noise exposure(100 dB SPL white noise,4 hours per day for 28 days)and control group(group B).The expression of IGF-1 both on the auditory cortex and hippocampus was measured and the ABR waveforms were recorded.ResuIts Compared with the group A,the num-ber of IGF-1 positive neurons as well as the expression of IGF-1 both in the auditory cortex and the hippocampus of the group B increased(P<0.05),the ABR threshold was significantly higher(P<0.05 )after long-term noise exposure.ConcIusion Chronic noise exposure induced the changes of the IGF-1 system which may play a part in the protection for the noise-induced damage of the central nervous system.

Objective To investigate the effect of ketamine on the mitochondrial function of rat neurons subjected to anoxia. Methods Primarily cultured rat hippocampal neurons were seeded in culture dishes (35 mm in diameter) at the density of 5×105-1×106 cells∕ml, and divided into 3 groups (n=11 each) using a random number table: control group, anoxia group and ketamine group. The neurons were exposed to 90% N2 plus 10% CO2 50 ml∕min for 5 min in anoxia group. In ketamine group, ketamine was added to the culture medium with the final concentration of 20 μmol∕L at 1 h before anoxia, and then the neurons were exposed to 90% N2 plus 10% CO2 50 ml∕min for 5 min. After the end of treatment in each group, the dead neurons were detected using trypan blue staining, the ATP content was determined by ATP bioluminescence assay, and mitochondrial membrane potential was measured by rhodamine 123 staining. Results Compared with control group, the mortality rate of hippocampal neurons was significantly in?creased, and the ATP content and mitochondrial membrane potential were significantly decreased in anoxia group and ketamine group ( P<0.05) . Compared with anoxia group, the mortality rate of hippocampal neu?rons was significantly decreased, and the ATP content and mitochondrial membrane potential were signifi?cantly increased in ketamine group (P<0.05). Conclusion The mechanism by which ketamine amelio?rates anoxia?induced damage to rat neurons is related to improved mitochondrial function.