煅石膏、骨形成蛋白及羟基磷灰石三元复合人工骨修复骨缺损的实验研究

以煅石膏(PLP）作为颗粒型羟基磷灰石(HA)人工骨粘接成形剂和骨形成蛋白(BMP)的载体，制成三元复合人工骨．分别用HA—bBMP、HA—PLP和单纯HA植入狗下颌骨实验性骨缺损中，采用组织学、定量组织学、免疫组织化学、X线摄片和扫描电镜观察的方法评价该复合人工骨的生物学性能。术后1，2，4，8和16周观察发现，HA—bBMP—PLP复合人工骨具有明显的骨诱导活性．PLP可充当BMP缓慢释放系统载体．增强BMP骨诱导活性，和作为颗粒型HA的粘接成形剂．使复合人工骨具有一定的可塑性和成形性，可达到准确的植入，植入后早期可有效防止HA颗粒移动。本研究证实．HA—bBMP—PLP三元复合人工骨不但可限制植入后HA颗粒的早期移动，更重要的是可以迅速增加新骨形成量．从形态和功能上大大提高了复合人工骨修复骨缺损的质量。     

介绍一种新型口腔正畸托槽定位安放器

研制托槽安放、定位功能融为一体的正畸器械。此新型器械使托槽安放及定位一次完成，取消安放托槽后再进行定位这一破坏粘结强度的步骤，操作方便，值得临床推广应用。     

Microbial leakage evaluation of the continuous wave of condensation

Coronal leakage has been recognized as a cause of pulpal and periradicular disease. Although cleaning and shaping of the root canal system is considered paramount, obturation of the system is an important step in endodontic success. The purpose of this study was to evaluate coronal bacterial leakage in teeth obturated with the System B continuous wave of condensation technique, followed by an Obtura II backfill, versus teeth obturated using the lateral condensation technique. Sixty single-rooted bilaterally matched teeth were evaluated in this study. An anaerobic bacterial leakage model was used. Results indicate that microbial coronal leakage occurs more quickly using lateral condensation than with the System B continuous wave of condensation and Obtura II backfill. This difference was statistically significant (p < or = 0.05). However, there was no statistical difference between groups 1 and 2 in the numbers of teeth that demonstrated bacterial leakage at the end of the study.     

变形链球菌CH43变链素Ⅰ基因片段的克隆及表达

目的:获得编码变形链球菌CH43变链素Ⅰ前体肽基因片段,并诱导其在不杀伤工程菌的前提下高效表达。方法:用PCR技术从变形链球菌CH43基因库中扩增出编码变链素Ⅰ成熟肽mutA基因片段相应大小的DNA片段,将片段与pMD18 T载体连接后测序。将测序正确的mutA按照BamHⅠ和HindⅢ酶切位点克隆入原核表达载体pProEX,将连接产物转化入E.coliDH5α,挑出阳性克隆,IPTG诱导表达重组的6×His融合蛋白。以IPTG浓度、A600值、诱导时间各梯度优化表达。结果:PCR获得的mutA序列与GenBank报道的一致(为147bp)。优化了诱导条件使重组载体在E.coliDH5α中高效表达,融合蛋白经SDS PAGE,在相对分子质量为5. 7×103处有特异的蛋白条带,在A600为1. 666时,加入IPTG至终浓度为1. 0mmol/L,诱导6h,目的蛋白表达量最高,占菌体总蛋白量的20%左右。结论:成功克隆变形链球菌CH43变链素ⅠmutA基因片段,并在E.coliDH5α中高效表达。     

Inverted U-Shaped Associations between Glycemic Indices and Serum Uric Acid Levels in the General Chinese Population: Findings from the China Cardiometabolic Disease and Cancer Cohort (4C) Study

Objective The relationship between serum uric acid(SUA)levels and glycemic indices,including plasma glucose(FPG),2-hour postload glucose(2 h-PG),and glycated hemoglobin(HbA1 c),remains inconclusive.We aimed to explore the associations between glycemic indices and SUA levels in the general Chinese population.Methods The current study was a cross-sectional analysis using the first follow-up survey data from The China Cardiometabolic Disease and Cancer Cohort Study.A total of 105,922 community-dwelling adults aged≥40 years underwent the oral glucose tolerance test and uric acid assessment.The nonlinear relationships between glycemic indices and SUA levels were explored using generalized additive models.Results A total of 30,941 men and 62,361 women were eligible for the current analysis.Generalized additive models verified the inverted U-shaped association between glycemic indices and SUA levels,but with different inflection points in men and women.The thresholds for FPG,2 h-PG,and HbA1 c for men and women were 6.5/8.0 mmol/L,11.0/14.0 mmol/L,and 6.1/6.5,respectively(SUA levels increased with increasing glycemic indices before the inflection points and then eventually decreased with further increases in the glycemic indices).Conclusion An inverted U-shaped association was observed between major glycemic indices and uric acid levels in both sexes,while the inflection points were reached earlier in men than in women.     

Comparative Study of the Genetic Diversity,Antimicrobial Resistance,and Pathogenicity of Aeromonas Isolates from Clinical Patients and Healthy Individuals

Objective This study was performed to compare the genetic diversity, virulence, and antimicrobial resistance of Aeromonas strains isolated from patients and healthy individuals. Methods A total of 38 clinical strains and 19 strains from healthy individuals were isolated from the samples collected in Ma'anshan City, Anhui Province. Their taxonomy was investigated using concatenated gyrB-cpn60 sequences, and their resistance to 12 antibiotics was evaluated. The pathogenicity of these strains was examined through beta-hemolysis, protease activity, and virulence gene assays. Results The 57 Aeromonas strains were divided into 55 sequence types. Of these types, 21 were novel, suggesting that their genetic diversity was high. These Aeromonas isolates could be divided into 7 species, and the positive rates of beta-hemolysis and protease activity were 49.1％ and 73.7％, respectively. The detection rate of clinical patients in terms of beta-hemolysis and protease activity was higher than that of healthy individuals. Among the four most common Aeromonas strains, A. dhakensis had the highest detection rate of virulence genes. The multidrug resistance rate of the clinical isolates was much higher than that of the strains isolated from healthy individuals. Conclusions The taxonomy, virulence properties, and antibiotic resistance of Aeromonas isolates from patients differ from those of the isolates from healthy individuals.     

Epidemiologic Features,Radiological Findings and Clinical Outcomes of 19 Patients with COVID-19 in a Single Center in Beijing,China

Objective To describe the epidemiologic, clinical, laboratory, and radiological characteristics and prognoses of COVID-19 confirmed patients in a single center in Beijing, China. Methods The study retrospectively included 19 patients with nucleic acid-confirmed SARS-CoV-2 infection at our hospital from January 20 to March 5, 2020. The final follow-up date was March 14, 2020. The epidemiologic and clinical information was obtained through direct communication with the patients or their family members. Laboratory results retrieved from medical records and radiological images were analyzed both qualitatively by two senior chest radiologists as well as quantitatively via an artificial intelligence software. Results We identified 5 family clusters (13/19, 68.4％) from the study cohort. All cases had good clinical prognoses and were either mild (3/19) or moderate (16/19) clinical types. Fever (15/19, 78.9％) and dry cough (11/19, 57.9％) were common symptoms. Two patients received negative results for more than three consecutive viral nucleic acid tests. The longest interval between an initial CT abnormal finding and a confirmed diagnosis was 30 days. One patient's nucleic acid test turned positive on the follow-up examination after discharge. The presence of radiological abnormalities was non-specific for the diagnosis of COVID-19. Conclusions COVID-19 patients with mild or no clinical symptoms are common in Beijing, China. Radiological abnormalities are mostly non-specific and massive CT examinations for COVID-19 screening should be avoided. Analyses of the contact histories of diagnosed cases in combination with clinical, radiological and laboratory findings are crucial for the early detection of COVID-19. Close monitoring after discharge is also recommended.