The nationwide distribution and trends of hepatitis C virus genotypes in mainland China

Comprehensive data on hepatitis C virus (HCV) genotypes distribution is critical for treatment regimen selection, vaccine design, and drug development. This study aimed to understand the dynamic distribution of HCV genotypes in Mainland China. Three hundred sixty-two studies published from January 1993 to December 2017 involving 64 891 samples (5133 injecting drug users, 2748 volunteer blood donors, 1509 former paid plasma donors, 160 sexually encounters, and 1992 human immunodeficiency virus (HIV)/HCV coinfection patients) were eligible for the quantitative synthesis estimation. Pooled proportion of HCV genotypes (and 95% confidence intervals [CIs]) was estimated through the Freeman-Tukey double arcsine transformation by period, region, and risk group. A sharp decline of the subtype 1b was observed in all regions except in northwestern and central regions. The genotypes 3 and 6 showed an obvious increase in southern and southwestern regions and have already spread nationwide. After 2010, subtype 1b was the most dominant variant in all regions and risk groups, accounting for 54.0% (95% CI, 51.9-56.1) of all national infections. Subtype 2a was the second most prevalent strain in all regions except in the south and southwest, with 15.4% (95% CI, 13.1-17.8) national infections. The subtype 6a in southern region and 3b and 3a in southwestern region had a higher proportion of infections than that in other regions. In addition, the genotypes 3 and 6 are already prevalent in almost all risk groups. The distribution of HCV genotypes were sharply shifting in China in the past three decades. The HCV subtype 1b posed a sharp decline, whereas genotypes 3 and 6 played an increasing role in the regional and populational HCV pandemic.     

The evolution and molecular characteristics of H9N2 avian influenza viruses in Jiangxi of China

To understand the evolution and molecular characteristics of Jiangxi H9N2 viruses, we isolated 17 viruses in 2011 and analyzed their characteristics. Phylogenetic analyses revealed that their hemagglutinin genes originate from JS/1/00-like sublineage, neuraminidase genes originate from BJ/94-like sublineage, PB1, PA, NP, and NS genes all come from SH/F/98-like sublineage, PB2 genes originate from ST/163/04-like sublineage, while M genes come from G1-like sublineage. Genotype analysis showed that our isolates were classified as genotype 57. Molecular analyses indicated that our strains contained specific sites characteristic of low-pathogenic viruses. The current study once again highlights the necessity for continued surveillance of novel H9N2 viruses.     

Preparation of nanocellulose and its potential in reinforced composites: A review

Cellulose is a kind of natural polymer material, which is composed of bundle-like fibrils. By peeling the fibrils layer by layer, the size of cellulose can be nanocrystallized, and nanofibers and nanocrystals with unique and potentially useful features can be prepared. As an emerging functional polymer material, nanocellulose has become a research hotspot in the field of technology. This review discusses the preparation of nanocellulose, including the commonly used hydrolysis, oxidation, physical and environmentally friendly ionic liquid methods. The advantages and disadvantages of different methods are also compared. And the review introduced the application of nanofiberized cellulose and nanocellulose crystals in the fields of thermosetting and thermoplastics, such as polylactic acid, polypropylene, epoxy resin and so on. The critical factors in the manufacturing of nanocellulose composites and mechanical properties are discussed to provide a reference for the further application and development of nanocellulose.     

Modeling Clinical Outcomes in Prostate Cancer: Application and Validation of the Discrete Event Simulation Approach

Objectives

Treatment landscape in prostate cancer has changed dramatically with the emergence of new medicines in the past few years. The traditional survival partition model (SPM) cannot accurately predict long-term clinical outcomes because it is limited by its ability to capture the key consequences associated with this changing treatment paradigm. The objective of this study was to introduce and validate a discrete-event simulation (DES) model for prostate cancer.

高山红景天多糖的硫酸化修饰及DPPH自由基清除活性研究

目的优选高山红景天多糖(RSP)的最佳硫酸化修饰条件,提高RSP的抗氧化活性。方法利用氯磺酸-吡啶法对RSP进行了硫酸化修饰,并通过单因素实验确定了硫酸化反应的最佳工艺条件;应用红外光谱(IR)和扫描电子显微镜(SEM)对RSP和硫酸化高山红景天多糖(S-RSP)的理化性质进行了分析;通过测定RSP和S-RSP对1,1-二苯基-2-三硝基苯肼(DPPH)自由基的清除能力,考察了S-RSP的取代度(DS)与多糖抗氧化活性之间的关系。结果当氯磺酸与吡啶的体积比为1∶4、反应时间为2 h、反应温度为60℃时,制得的S-RSP的含硫量最大值为18.83%,取代度最大值为2.38。RSP经硫酸化修饰后,增强了其抗氧化活性,S-RSP的DS与DPPH自由基清除能力存在一定的正比例关系。结论氯磺酸与吡啶的体积比影响S-RSP的DS大小;RSP经硫酸化修饰后通过改变多糖的极性而增加了其抗氧化能力。     

Infant ectopic cervical thymus in submandibular region

Sporadic cases have been reported of ectopic thymic tissue formed along the path of embryologic descent from the mandibular region to the mediastinum, usually manifesting as an asymptomatic mass. Here is reported the case of an 8-month-old boy with a tender palpable mass in the right upper lateral neck. Preoperative posteroanterior chest radiograph revealed normal structures in the mediastinum superior including the thymus. Magnetic resonance imaging showed a 4-cm x 4-cm soft-tissue mass in the left submandibular region. Surgical resection was performed and histopathologic examination showed that the mass was composed of thymic lymphoid tissue and epithelial cells. Immunohistochemical features included positive expression of LCA, CKpan, EMA, CD20 and CD43 antibodies. The clinical 14-month follow up was negative and the child was growing normally after operation. Ectopic thymus in the submandibular region is uncommon; surgical treatment is the definitive means of pathological diagnosis. Prior to surgery, the presence of a mediastinal thymus should be confirmed to prevent the risk of a total thymectomy.     

激光焊接间距对牙科铸造纯钛性能影响的实验研究

目的:研究激光焊接铸造纯钛时不同的焊接间距对纯钛性能的影响。方法:将铸造钛试样按照焊接间距的大小分为4组:0.00、0.25、0.50、1.00mm组,肉眼、扫描电镜观察焊缝区外观,测试焊件的抗拉强度,整铸件为对照组。结果:各试验组焊缝区显示全层焊透、无明显气孔等焊接缺陷,断口电镜显示为延展性(韧窝)与脆性(气孔、裂纹)共存的形貌。各实验组与对照组间抗拉强度方差分析结果显示差异无显著性(P>0.05)。结论:不同的焊接间距对铸钛的机械性能无明显影响。     

CEREC陶瓷修复体的临床应用

在临床修复中，传统的瓷嵌体等修复体的制作，至少需要二次就诊时间。随着光学扫描方法和计算机辅助制作嵌体技术的应用，省去了目前操作的印模、灌模、蜡型等技术。CEREC系统运用光学印模方法以及CAD-CAM技术，将一预成陶瓷块铣磨成修复体，使牙科医生能在牙体预备后即制作一个色泽自然的陶瓷修复体，并即时粘固于预备牙上，这不仅提高了工作效率，更重要的是提高了修复体的质量。该系统不仅可以制作嵌体和高嵌体，而且还可制作各种贴面。本文的目的是介绍和描述CEREC系统制作修复体的方法步骤，并就临床应用中的有关问题加以探讨。     

Effect of dynamic loading on the integrity of the interface between root canal and obturation materials

The purpose of this study was to evaluate the effect of occlusal load on the integrity of root canal obturation. Maxillary anterior teeth were cleaned, shaped, and obturated with either gutta-percha (GP)/AH Plus or Resilon/Epiphany. Afterwards, teeth were placed under 100 N force at 2 Hz for 22 hours in a 37 degrees C water bath. Teeth were sectioned and examined for disruption in the integrity of the obturation by using optical microscopy. The length of the separation between the obturation and the root canal walls was measured and compared statistically. GP and Resilon obturated canals subjected to occlusal load displayed significantly greater interface disruption compared with unloaded controls (p < .05). The results indicate that occlusal load generates separation forces on the obturation interface that might compromise the sealing ability of the obturation.     

ICRF154,加热对腺样囊性癌ACC-2细胞放射增敏的实验研究

目的研究ICRF154和加热对腺样囊性癌ACC－2细胞放射增敏的作用。方法以腺样囊性癌ACC－2细胞作为实验模型，用新抗癌药ICRF154在乏氧条件下研究该药的放射增敏性以及加热对放射的增敏效应。结果在0．2mmol／L浓度和2个小时作用时间下，ICRF154对ACC－2细胞有放射增敏作用，增敏比为1．22、放射后加热43℃，30分钟对ACC－2细胞有显著的放射增敏作用，增敏比为1．51。用上述浓度和作用时间ICRF154，作用于ACC－2细胞后进行照射，照华后即行加热43℃，30分钟，增敏比为1．67，表明ICRF154和加热的放射增敏作用有加成效应。结论ICRF154的放射增敏机制可能与其抑制拓扑异构酶Ⅱ，从而抑制DNA损伤的修复有关。