软组织力学进展

概述了软组织力学最近的发展,介绍了在体和离体皮肤的实验方法和实验装置,进一步说明了成形外科中皮肤扩张的力学和组织化学研究。另外对用凹痕法和本构方程导得的肺的增量弹性模量结果作了比较,最后讨论了对键和韧带结构和功能有影响的以下诸因素:冷冻储存、温度、年龄、功能适应和内环境稳定。     

改性组分对遇水膨胀橡胶吸水膨胀性能影响的逾渗理论分析

根据逾渗理论模型对自制遇水膨胀橡胶的平衡吸水膨胀率与吸水树脂用量之间的关系进行了分析和相关的计算,并确定了该遇水膨胀橡胶共混体系的临界基层厚度Tc,在此基础上证明了所制备的遏水膨胀橡胶共混体系的平衡吸水膨胀率（Sw）与复合球体积分数（φs）间的关系服从逾渗理论的标度定律关系,并求得了不同共混体系的临界指数g值;最后将改性吸水树脂中改性组分用量与临界指数g值的大小、遇水膨胀橡胶平衡吸水膨胀性能之间的关系等相联系进行分析。结果表明,临界指数g值越接近理论值,遇水膨胀橡胶的平衡吸水膨胀率越大,当改性组分质量分数为30％,吸水树脂用量为30质量份时,遇水膨胀橡胶的平衡吸水膨胀率达到438％,临界指数g值为0．44,其主要原因是改性组分的引入使吸水树脂在橡胶中的分散性得到了明显的改善。     

Ameliorative Effects of PACAP against Cartilage Degeneration. Morphological,Immunohistochemical and Biochemical Evidence from in Vivo and in Vitro Models of Rat Osteoarthritis

Osteoarthritis (OA); the most common form of degenerative joint disease, is associated with variations in pro-inflammatory growth factor levels, inflammation and hypocellularity resulting from chondrocyte apoptosis. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide endowed with a range of trophic effects in several cell types; including chondrocytes. However; its role in OA has not been studied. To address this issue, we investigated whether PACAP expression is affected in OA cartilage obtained from experimentally-induced OA rat models, and then studied the effects of PACAP in isolated chondrocytes exposed to IL-1β in vitro to mimic the inflammatory milieu of OA cartilage. OA induction was established by histomorphometric and histochemical analyses. Changes in PACAP distribution in cartilage, or its concentration in synovial fluid (SF), were assessed by immunohistochemistry and ELISA. Results showed that PACAP abundance in cartilage tissue and SF was high in healthy controls. OA induction decreased PACAP levels both in affected cartilage and SF. In vitro, PACAP prevented IL-1β-induced chondrocyte apoptosis, as determined by MTT assay; Hoechst staining and western blots of apoptotic-related proteins. These changes were also accompanied by decreased i-NOS and COX-2 levels, suggesting an anti-inflammatory effect. Altogether, these findings support a potential role for PACAP as a chondroprotective agent for the treatment of OA.     

Oral Microbiota Features in Subjects with Down Syndrome and Periodontal Diseases: A Systematic Review

Down syndrome (DS) is a genetic disorder associated with early-onset periodontitis and other periodontal diseases (PDs). The present work aimed to systematically review the scientific literature reporting studies in vivo on oral microbiota features in subjects with DS and related periodontal health and to highlight any correlation and difference with subjects not affected by DS, with and without PDs. PubMed, Web of Science, Scopus and Cochrane were searched for relevant studies in May 2021. The participants were subjects affected by Down syndrome (DS) with and without periodontal diseases; the study compared subjects with periodontal diseases but not affected by DS, and DS without periodontal diseases; the outcomes were the differences in oral microbiota/periodontopathogen bacterial composition among subjects considered; the study design was a systematic review. Study quality was assessed with risk of bias in non-randomized studies of interventions (ROBINS-I). Of the 954 references retrieved, 26 studies were considered. The conclusions from the qualitative assessment of the papers revealed an increasing knowledge over the last years of the microbiota associated with DS and their periodontal diseases, in comparison with healthy subjects and subjects with other kinds of mental disabilities. Few data have emerged on the mycobiome and virobiome of DS, hence, further investigations are still necessary.     

聚己内酯降解速率的调控及改性的研究进展

组织工程学的兴起使聚己内酯成为研究的热点。聚己内酯因优越的性能成为组织工程中支架材料的热门选择。然而,聚己内酯的降解速率过慢,需要3~4年,而应用于牙槽骨再生的支架材料的理想目标是在5~6个月内完全降解,这大大限制了聚己内酯的临床应用。针对聚己内酯降解速率的调控方法进行了梳理,包括与不同的材料共混改性、表面处理等方法,并对聚己内酯作为组织工程支架材料的未来进行了展望。     

裂纹格特蛤韧带中的天然生物光子结构

采用光学显微镜、微型光纤光谱仪和扫描电镜对海产裂纹格特蛤韧带的光学性质以及纳米结构进行了研究。结果表明:韧带是由文石纤维和蛋白质组成的二维天然生物光子材料。另外,首次发现纤维的粒径和间距与韧带位置有关,其值从背侧的133 nm、149nm分别增大到腹侧的156nm、175nm,从而导致韧带反射谱自背侧至腹侧发生红移,反射峰分别位于476nm和544nm处。     

一种天然湿敏性二维可调光子带隙材料及其光学性能研究

采用反射光谱、扫描电镜及理论模拟计算对三角帆蚌韧带的结构色及微结构进行了较为系统的研究.结果表明:韧带从湿润到干燥状态,其反射峰波长从460nm蓝移至423nm,且反射峰强度逐渐降低,相应的颜色从蓝色转变为背景色褐色.韧带的结构色是由韧带中定向排列的文石纤维和蛋白质构成的二维光子结构引起的,该结构中文石纤维粒径为(122±14)nm,相邻文石纤维中心间距为(133±15)nm.水对韧带的反射峰强度及光子带隙范围具有明显的调节作用,可见韧带具有湿敏性二维可调光子带隙结构特征,属于一种天然的湿敏性二维可调光子带隙材料.     

MMPs and TIMPs Expression Levels in the Periodontal Ligament during Orthodontic Tooth Movement: A Systematic Review of In Vitro and In Vivo Studies

Background: During orthodontic tooth movement (OTM), applied orthodontic forces cause an extensive remodeling of the extracellular matrix (ECM) in the periodontal ligament (PDL). This is mainly orchestrated by different types of matrix metalloproteinases (MMPs) and their tissue inhibitors of matrix metalloproteinases (TIMPs), which are both secreted by periodontal ligament (PDL) fibroblasts. Multiple in vitro and in vivo studies already investigated the influence of applied orthodontic forces on the expression of MMPs and TIMPs. The aim of this systematic review was to explore the expression levels of MMPs and TIMPs during OTM and the influence of specific orthodontic force-related parameters. Methods: Electronic article search was performed on PubMed and Web of Science until 31 January 2021. Screenings of titles, abstracts and full texts were performed according to PRISMA, whereas eligibility criteria were defined for in vitro and in vivo studies, respectively, according to the PICO schema. Risk of bias assessment for in vitro studies was verified by specific methodological and reporting criteria. For in vivo studies, risk of bias assessment was adapted from the Joanna Briggs Institute Critical Appraisal Checklist for analytical cross-sectional study. Results: Electronic article search identified 3266 records, from which 28 in vitro and 12 in vivo studies were included. The studies showed that orthodontic forces mainly caused increased MMPs and TIMPs expression levels, whereas the exact effect may depend on various intervention and sample parameters and subject characteristics. Conclusion: This systematic review revealed that orthodontic forces induce a significant effect on MMPs and TIMPs in the PDL. This connection may contribute to the controlled depletion and formation of the PDLs’ ECM at the compression and tension site, respectively, and finally to the highly regulated OTM.     

The Effect of Liposomal Curcumin as an Anti-Inflammatory Strategy on Lipopolysaccharide e from Porphyromonas gingivalis Treated Endothelial Committed Neural Crest Derived Stem Cells: Morphological and Molecular Mechanisms

Curcumin, a yellow polyphenol extracted from the turmeric root is used as a diet supplement. It exhibits anti-inflammatory, antioxidant, and antitumor properties by modulating different intracellular mechanisms. Due to their low solubility in water, the curcumin molecules must be encapsulated into liposomes to improve the bioavailability and biomedical potential. For the periodontal tissue and systemic health, it is essential to regulate the local inflammatory response. In this study, the possible beneficial effect of liposomes loaded with curcumin (CurLIP) in neural crest-derived human periodontal ligament stem cells (hPDLSCs) and in endothelial-differentiated hPDLSCs (e-hPDLSCs) induced with an inflammatory stimulus (lipopolysaccharide obtained from Porphyromonas gingivalis, LPS-G) was evaluated. The CurLIP formulation exhibited a significant anti-inflammatory effect by the downregulation of Toll-like receptor-4 (TLR4)/Myeloid differentiation primary response 88 (MyD88)/nuclear factor kappa light chain enhancer of activated B cells (NFkB)/NLR Family Pyrin Domain Containing 3 (NLRP3)/Caspase-1/Interleukin (IL)-1β inflammation cascade and reactive oxygen species (ROS) formation. Moreover, the exposure to LPS-G caused significant alterations in the expression of epigenetic modifiers, such as DNA Methyltransferase 1 (DNMT1) and P300, while the CurLIP treatment showed physiological expression. Overall, our in vitro study provides novel mechanistic insights into the intracellular pathway exert by CurLIP in the regulation of inflammation and epigenetic modifications.     

Contribution to the optimisation of artificial ligament mechanical properties

In this work, artificial anterior cruciate ligaments were manufactured using braiding process. The mechanical behaviour of circular braids under tensile loads was studied. These braids were manufactured from different yarns and materials. A study of the effect of yarns characteristics and the machine parameters on the braid mechanical properties was done. Predictive models of the braid mechanical response based on the constituent yarn characteristics and the machine parameters have been developed. The last part of this study has been devoted to optimise the braid mechanical properties to be close to those of native ligament.