Analysis on genotype distributions and epidemiological characteristics of Yersinia pestis plague foci in Gansu province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the genotype distributions and epidemiological characteristics of Yersinia pestis in Gansu province.</p><p><b>METHODS</b>Primers were designed according to the confirmed 23 differential sections, to genotype the 202 Yersinia pestis DNA of Gansu province by PCR, and to analyze its distribution and epidemiological characteristics.</p><p><b>RESULTS</b>Yersinia pestis in Gansu province could be divided into eight genotypes: 1b, 5, 7, 8, 13, 26, new genotype 1 (GS1) and new genotype 2 (GS2). They were distributed in various regions. 1b, 8 and GS1 genotypes of Yersinia pestis had been identified since 1960s but the 7, 13 and 26 genotypes had not been isolated for more than 40 years while GS2 and 5 genotypes had been isolated since 1990s.</p><p><b>CONCLUSION</b>1b, 8 and GS1 genotypes of Yersinia pestis continued to be violently prevalent since 1960s but 7, 13 and 26 genotypes had not been isolated for more than 40 years while GS2 and 5 genotypes had started to be popular since 1990s.</p>

Evaluation of the effect of up-converting phosphor technology in detection of plague antigen-antibody by receiver operating characteristic curve method / 中国地方病学杂志

Objective To evaluate the effect of up-converting phosphor technology(UPT) in detection of plague antigen-antibody by receiver operating characteristic curve (ROC) method,and to provide a scientific basis for field application of UPT rapid detection technology in plague prevention and control.Methods Two hundred and twenty four serum samples were collected from Marmots and ground squirrels in the plague foci,Yersinia pestis antibody was detected by UPT,ELISA,Colloidal-gold Strips and IHA,respectively; 108 organs and bone marrow samples were collected,and Yersinia pestis antigens were detected by UPT,ELISA,PCR and RIHA,respectively.IHA was used as the gold standard for antibody test results,RIHA,PCR + Colloidal-gold Strips,PCR + ELISA were used as the gold standard for antigen test results.The results were evaluated using ROC method.Results Antibodies detection:the AUCs of UPT,ELISA and Colloidal-gold Strips were greater than 0.5.The difference between UPT and other methods was not statistically significant (z =1.204,P ＞ 0.05).Antigen detection:the AUCs of UPT,ELISA,Colloidal-gold Strips and PCR were greater than 0.5.There was no statistical difference between UPT and other methods(z =0.866,P ＞ 0.05).Conclusions UPT as a new technology works well in the detection of plague antigen-antibody.The technology is simple,fast,accurate,and suitable for on-site monitoring of plague,emergency treatment of sudden plague,and suitable for promotion.

Corrosion resistance of Ti-Cu alloy / 中华口腔医学杂志

<p><b>OBJECTIVE</b>to investigate the corrosion behavior of Ti-Cu alloy in 0.9%NaCl solution and in acidified 0.9%NaCl solution.</p><p><b>METHODS</b>the microstructure of Ti-Cu alloys were characterized by means of X-ray diffraction (XRD). The electrochemical behavior of Ti-Cu alloy in two solutions (namely 0.9%NaCl solution and acidified 0.9%NaCl solution) was tested. Commercial pure Ti and 316L stainless steel were used as control.</p><p><b>RESULTS</b>Ti-Cu alloys were composed by α-Ti and Ti(2)Cu intermetallic compound. After 3500 s immersion, the open circuit potential (OCP) values of pure Ti, Ti-5Cu alloy and Ti-10Cu alloy in 0.9% NaCl solution were -188, -181 and -173 mV, respectively. In 0.9% NaCl solution with lactic acid added, the OCP values were -143, -158 and -109 mV, respectively. In potentiodynamic polarization tests, the passive current densities of pure Ti and Ti-5Cu alloys were about 20 µA/cm(2). However, 316L stainless steel experienced pitting corrosion.</p><p><b>CONCLUSIONS</b>it was possible to establish the following relation for their corrosion resistances: pure Ti≈Ti-5Cu > Ti-10Cu > 316L stainless steel. The addition of lactic acid in the solution did not compromise the corrosion resistance of Ti-Cu alloys.</p>

Root resection by Er:YAG laser: a scanning electron microscope study / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the difference of the surface of root resection by Er:YAG laser, ultrasonic or high-speed handpiece with scanning electron microscope (SEM), and to evaluate the possibility of using Er:YAG laser on the root resection in clinical application.</p><p><b>METHODS</b>Thirty maxillary central incisors were divided into three groups (Er:YAG laser group, ultrasonic group, high-speed handpiece group), and the root resection were made at root tip 3 mm with Er:YAG laser, ultrasonic instrument or long needle diamond bur according to grouping. The surface of the root resection by SEM in the aspects of debris, smear layer, opened dentinal tubules, cracks and ablation characteristics were compared.</p><p><b>RESULTS</b>The examination revealed that Er:YAG laser group and ultrasonic group had no or little debris and smear layer and with opened dentinal tubules. High-speed handpiece group had great amount of debris and smear layer and without opened dentinal tubules. Cracks were observed in ultrasonic group and high-speed handpiece group, no in Er:YAG laser group. There were ablation characteristics in ultrasonic group and high-speed handpiece group, but no in Er:YAG laser group.</p><p><b>CONCLUSION</b>From the morphological aspect, Er:YAG laser has much more advantage than ultrasonic instrument and diamond bur for the root resection.</p>

Comparison of clinical effect of different tapered gutta-percha root filling with warm vertical condensation / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the clinical effect of different tapered gutta-percha root filling by warm vertical condensation with immediate postoperative radiographs and one year follow-up.</p><p><b>METHODS</b>40 maxillary anterior teeth with single, straight canals were divided into two equal groups. The teeth were instrumented with Hero 642 rotary nickel-titanium files to a master file 0.06 taper No. 30. Group 1 was obturated with 0.02 tapered gutta-percha using System B for downpack and Obtura II for backfilling. Group 2 was the same but 0.06 tapered gutta-percha. Every tooth's X-ray radiographs of immediate postoperative and one year follow-up were taken. In order to compare the quality of root canal filling, the rate of filling material extrusion, and the rate of obturation of lateral canals in each group were evaluated by X-ray radiographs. The clinical effect of one year follow-up's radiographs of the two groups was compared too.</p><p><b>RESULTS</b>There was no significant difference in two groups on the quality of the root canal filling, obturation of lateral canals, and filling material extrusion. The success of the therapy was similar. But the 0.06 tapered gutta-percha group showed more quickly healing trend on apical periodontitis.</p><p><b>CONCLUSION</b>When single, straight root canals were obturated using warm vertical condensation, adaptively tapered gutta-percha showed better clinical effect.</p>

Quality of apical seal of differently tapered gutta-percha cone using warm vertical condensation technique / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to compare the quality of apical seal of the canals that obturated with differently tapered gutta-percha cone using continuous wave technique.</p><p><b>METHODS</b>62 extracted human mandible incisors were prepared with Gates-Glidden drill and Hero642 to a final file of No. 30 and 0.06 taper. The teeth were randomly separated into 0.02 taper group (30 teeth), 0.06 taper group (30 teeth) and positive control group (2 teeth). The teeth of 0.02 taper group and 0.06 taper group were respectively obturated with a 0.02, or 0.06 tapered gutta-percha cone and Cortisomol sealer using warm vertical condensation technique separately. The teeth of positive control group were not obturated. In 0.02 taper group and 0.06 taper group, 10 teeth were placed in India ink for 24 hours, 10 teeth were placed in India ink for 10 days, 10 teeth were placed in India ink for 90 hours after 67 days storage in Hank's balanced salt solution. The teeth of positive control group were placed in India ink for 24 hours. The apical leakage was evaluated by the linear measurement under the stereomicroscope.</p><p><b>RESULTS</b>The dye penetration of positive control group was along the whole canals. The apical leakage of 0.02 taper group increased along with time, while no difference was found among 0.06 taper group. There was a significant difference in the degree of leakage between 0.02 taper group and 0.06 taper group in 67 days (P = 0.041), but not in 24 hours and 10 days groups (P = 0.601, P = 0.471).</p><p><b>CONCLUSION</b>Better apical seal was obtained when using the same tapered gutta-percha cone with root canal.</p>

Isolation and Characterization of a Temperature-sensitive p-Nitrophenol Degradation Related Genes Mutant Strain / 微生物学通报

A temperature-sensitive mutant strain was isolated after transposon mutagenesis with Tn5 and named MT54.PCR was carried out with primers designed according to the sequence of transposon,the PCR products showed that the MT54 carried transposon in the genome. The mutant grew well at 30℃in minimal medium(MM)containing p-nitrophenol(PNP)as sole carbon source,while it cannot grow at 37℃in the same medium,NO_2.detection results also proved that.Comparing the degradation rate of PNP and hydroquinone of MT54 and DLL-E4 at different temperature,it was speculated that the mutant site locate in the PNP degradation related genes.