Influence of connection type on the biomechanical behavior of distal extension mandibular removable partial dentures supported by implants and natural teeth

Few studies are performed to evaluate the influence of connection type on the stress distribution of distal extension mandibular removable partial dentures (RPDs) supported by both implants and natural teeth. In this study, five three-dimensional finite element models were prepared to simulate mandibular bilateral partially edentulous arches. Four were RPDs supported by both implants and natural teeth, and the other one was RPDs supported only by natural teeth. The maximum equivalent (EQV) stress values of bone around implants, the abutments, and the mucosa displacements of the related supporting structures were measured. It was found that a non-rigid telescopic coping was more favorable to protect the implant than a rigid telescopic coping. Compared with other connection types, the easy resilient attachment (ERA) system seemed to be effective to associate implant without complications. However, the results obtained in the present study should be cautiously interpreted in the clinic.     

Ghrelin治疗脑出血大鼠脑水肿及MMP-9表达的影响

目的:研究Ghrelin对大鼠脑出血后脑水肿及脑组织中基质金属蛋白酶-9(MMP-9)表达的影响。方法:选取雄性SD大鼠80只,随机分为对照组(NC组)20只、假手术组(SHAM组)20只、脑出血组(ICH组)20只、Ghrelin治疗组(Ghrelin组)20只。利用自体动脉血注入法建立大鼠脑出血模型;Ghrelin组于建立脑出血模型后经股静脉注射Ghrelin 10 nmol/Kg·d。分别于12 h、24 h、3d、5 d、7 d时间点根据Berderson评分法评估各组大鼠神经系统功能;利用干湿重法测定各组大鼠脑组织含水量;利用蛋白质免疫印迹法(WB)检测脑组织中MMP-9表达情况。结果:在12 h、24 h、3 d、5 d、7 d,ICH组、Ghrelin组大鼠Berderson评分及脑组织含水量高于NC组、SHAM组(P0.05);在5 d、7 d,ICH组大鼠Berderson评分及脑组织含水量高于Ghrelin组(P0.05)。WB结果表明在12 h、24 h、3 d、5 d、7 d,ICH组大鼠脑组织中MMP-9的表达均高于NC组、SHAM组(P0.05);Ghrelin组MMP-9的表达在12 h、24 h、3 d高于NC组、SHAM组(P0.05),在5 d、7 d,与NC组、SHAM组无明显差异(P0.05);在5 d、7 d,ICH组MMP-9表达高于Ghrelin组(P0.05)。结论:在本研究中,Ghrelin可以在5 d后降低脑出血大鼠脑组织中MMP-9的表达程度,从而减轻脑水肿,改善脑出血大鼠神经功能。     

水稻耐储藏特性三年动态鉴定与QTL分析

种子耐储藏特性是粮食作物的特殊农艺性状之一, 耐储藏性能对种子生产和种质资源保存有重要意义。以粳型超级稻龙稻5 (LD5)和高产籼稻中优早8 (ZYZ8)杂交衍生的重组自交系(RILs)群体(共180个株系)为实验材料, 自然高温高湿条件下放置1年、2年和3年后, 对不同储藏时段种子发芽率进行比较, 并利用223个分子标记的遗传图谱进行动态QTL鉴定。结果表明, 不同储藏时段龙稻5的发芽率均显著低于中优早8, 株系间耐储性存在较大差异; 不同储藏时段发芽率显著相关, 相邻存储时段发芽率关系紧密。共检测到17个耐储性相关的QTLs, 3个老化时段分别检测到5、4和3个, 检测到5个动态条件QTLs, 单一QTL解释5.60%-32.76%的表型变异, 加性效应在-16.78%-16.95%范围内。主效QTL簇qSSC2、qSSC6、qSSC7和qSSC8能调控不同储藏时段的发芽率, qSSC6具有明显降低发芽率的效应。共检测到26对上位性互作位点, 主效QTL qSS1和qSS4参与上位性互作, 这表明上位性互作是调控耐储藏性状的重要遗传组成。研究结果为水稻(Oryza sativa)耐储性相关QTL的精细定位奠定基础, 同时丰富了耐储性分子标记辅助选择育种的基因资源。     

Evolution of genes and genomes: an emerging paradigm in life science

<正>Traditional molecular biology, defined in a broad sense to include most of life science research that focuses on single or a few genes to understand their functions and application values to medicine and agriculture, has generated interesting and important accomplishments. Meanwhile, in recent years,a new paradigm is emerging in biological research that further adds new approaches and new dimension of scientific     

Transplantation of adult spinal cord grafts into spinal cord transected rats improves their locomotor function

Grafted embryonic central neural tissue pieces can recover function of hemisected spinal cord in neonatal rats and promote axonal growth in adults. However, spinal cord segments from adults have not been used as donor segments for allogeneic transplantation. Here, we utilized adult spinal cord tissue grafts(aSCGs) as donor constructs for repairing complete spinal cord injury(SCI). Moreover, to provide a favourable microenvironment for SCI treatment, a growth factor cocktail containing three growth factors(brain-derived neurotrophic factor, neurotrophin-3 and vascular endothelial growth factor), was applied to the aSCG transplants. We found that the locomotor function was significantly improved 12 weeks after transplantation of aSCGs into the spinal cord lesion site in adult rats. Transplantation of aSCGs combined with these growth factors enhanced neuron and oligodendrocyte survival and functional restoration. These encouraging results indicate that treatment of complete SCI by transplanting aSCGs, especially in the presence of growth factors, has a positive effect on motor functional recovery, and therefore could be considered as a possible therapeutic strategy for SCI.     

The role of autophagy in the pathogenesis of exposure keratitis

Incomplete tear film spreading and eyelid closure can cause defective renewal of the ocular surface and air exposure‐induced epithelial keratopathy (EK). In this study, we characterized the role of autophagy in mediating the ocular surface changes leading to EK. Human corneal epithelial cells (HCECs) and C57BL/6 mice were employed as EK models, respectively. Transmission electron microscopy (TEM) evaluated changes in HCECs after air exposure. Each of these models was treated with either an autophagy inhibitor [chloroquine (CQ) or 3‐methyladenine (3‐MA)] or activator [Rapamycin (Rapa)]. Immunohistochemistry assessed autophagy‐related proteins, LC3 and p62 expression levels. Western blotting confirmed the expression levels of the autophagy‐related proteins [Beclin1 and mammalian target of rapamycin (mTOR)], the endoplasmic reticulum (ER) stress‐related proteins (PERK, eIF2α and CHOP) and the PI3K/Akt/mTOR signalling pathway‐related proteins. Real‐time quantitative PCR (qRT‐PCR) determined IL‐1β, IL‐6 and MMP9 gene expression levels. The TUNEL assay detected apoptotic cells. TEM identified autophagic vacuoles in both EK models. Increased LC3 puncta formation and decreased p62 immunofluorescent staining and Western blotting confirmed autophagy induction. CQ treatment increased TUNEL positive staining in HCECs, while Rapa had an opposite effect. Similarly, CQ injection enhanced air exposure‐induced apoptosis and inflammation in the mouse corneal epithelium, which was inhibited by Rapa treatment. Furthermore, the phosphorylation status of PERK and eIF2α and CHOP expression increased in both EK models indicating that ER stress‐induced autophagy promoted cell survival. Taken together, air exposure‐induced autophagy is indispensable for the maintenance of corneal epithelial physiology and cell survival.     

Picroside II attenuates hyperhomocysteinemia‐induced endothelial injury by reducing inflammation,oxidative stress and cell apoptosis

Picroside II (P‐II), one of the main active components of scrophularia extract, which have anti‐oxidative, anti‐inflammatory effects, but its effect on hyperhomocysteinemia (HHcy) induced endothelial injury remains to be determined. Here, we test whether P‐II protects HHcy‐induced endothelial dysfunction against oxidative stress, inflammation and cell apoptosis. In vitro study using HUVECs, and in hyperhomocysteinemia mouse models, we found that HHcy decreased endothelial SIRT1 expression and increased LOX‐1 expression, subsequently causing reactive oxygen species generation, up‐regulation of NADPH oxidase activity and NF‐κB activation, thereby promoting pro‐inflammatory response and cell apoptosis. Blockade of Sirt1 with Ex527 or siRNASIRT1 increased LOX‐1 expression, whereas overexpression of SIRT1 decreased LOX‐1 expression markedly. P‐II treatment significantly increased SIRT1 expression and reduced LOX‐1 expression, and protected against endothelial cells from Hcy‐induced oxidative injury, inflammation and apoptosis. However, blockade of SIRT1 or overexpression of LOX‐1 attenuated the therapeutic effects of P‐II. In conclusion, our results suggest that P‐II prevents the Hcy induced endothelial damage probably through regulating the SIRT1/LOX‐1 signaling pathway.     

Cigarette smoke extract alters genome‐wide profiles of circular RNAs and mRNAs in primary human small airway epithelial cells

As a novel kind of non‐coding RNA, circular RNAs (circRNAs) were involved in various biological processes. However, the role of circRNAs in the developmental process of chronic obstructive pulmonary disease (COPD) is still unclear. In the present study, by using a cell model of COPD in primary human small airway epithelial cells (HSAECs) treated with or without cigarette smoke extract (CSE), we uncovered 4,379 previously unknown circRNAs in human cells and 903 smoke‐specific circRNAs, with the help of RNA‐sequencing and bioinformatic analysis. Moreover, 3,872 up‐ and 4,425 down‐regulated mRNAs were also identified under CSE stimulation. Furthermore, a putative circRNA‐microRNA‐mRNA network was constructed for in‐depth mechanism exploration, which indicated that differentially expressed circRNAs could influence expression of some key genes that participate in response to pentose phosphate pathway, ATP‐binding cassette (ABC) transporters, glycosaminoglycan biosynthesis pathway and cancer‐related pathways. Our research indicated that cigarette smoke had an influence on the biogenesis of circRNAs and mRNAs. CircRNAs might be involved in the response to CSE in COPD through the circRNA‐mediated ceRNA networks.