Impact of High-Molecular-Weight Hyaluronic Acid on Gene Expression in Rabbit Achilles Tenocytes In Vitro

(1) Background: Surgical tendon repair often leads to adhesion formation, leading to joint stiffness and a reduced range of motion. Tubular implants set around sutured tendons might help to reduce peritendinous adhesions. The lubricant hyaluronic acid (HA) is a viable option for optimizing such tubes with the goal of further enhancing the anti-adhesive effect. As the implant degrades over time and diffusion is presumed, the impact of HA on tendon cells is important to know. (2) Methods: A culture medium of rabbit Achilles tenocytes was supplemented with high-molecular-weight (HMW) HA and the growth curves of the cells were assessed. Additionally, after 3, 7 and 14 days, the gene expression of several markers was analyzed for matrix assembly, tendon differentiation, fibrosis, proliferation, matrix remodeling, pro-inflammation and resolution. (3) Results: The addition of HA decreased matrix marker genes, downregulated the fibrosis marker α-SMA for a short time and slightly increased the matrix-remodeling gene MMP-2. Of the pro-inflammatory marker genes, only IL-6 was significantly upregulated. IL-6 has to be kept in check, although IL-6 is also needed for a proper initial inflammation and efficient resolution. (4) Conclusions: The observed effects in vitro support the intended anti-adhesion effect and therefore, the use of HMW HA is promising as a biodegradable implant for tendon repair.     

The HIV-1 Gag Protein Displays Extensive Functional and Structural Roles in Virus Replication and Infectivity

Once merely thought of as the protein responsible for the overall physical nature of the human immunodeficiency virus type 1 (HIV-1), the Gag polyprotein has since been elucidated to have several roles in viral replication and functionality. Over the years, extensive research into the polyproteins’ structure has revealed that Gag can mediate its own trafficking to the plasma membrane, it can interact with several host factors and can even aid in viral genome packaging. Not surprisingly, Gag has also been associated with HIV-1 drug resistance and even treatment failure. Therefore, this review provides an extensive overview of the structural and functional roles of the HIV-1 Gag domains in virion integrity, functionality and infectivity.     

移动IPv6安全绑定更新机制研究

介绍了移动IPv6网络中节点移动后进行三角路由优化所引出的绑定更新安全问题,阐述了在非PKI体系中解决绑定更新安全隐患的几种机制;在阐述的同时对这些机制进行了安全性分析,最后对这几种机制从安全性角度进行比较.     

Association of Ligamentum Flavum Hypertrophy with Adolescent Idiopathic Scoliosis Progression—Comparative Microarray Gene Expression Analysis

The role of the ligamentum flavum (LF) in the pathogenesis of adolescent idiopathic scoliosis (AIS) is not well understood. Using magnetic resonance imaging (MRI), we investigated the degrees of LF hypertrophy in 18 patients without scoliosis and on the convex and concave sides of the apex of the curvature in 22 patients with AIS. Next, gene expression was compared among neutral vertebral LF and LF on the convex and concave sides of the apex of the curvature in patients with AIS. Histological and microarray analyses of the LF were compared among neutral vertebrae (control) and the LF on the apex of the curvatures. The mean area of LF in the without scoliosis, apical concave, and convex with scoliosis groups was 10.5, 13.5, and 20.3 mm², respectively. There were significant differences among the three groups (p < 0.05). Histological analysis showed that the ratio of fibers (Collagen/Elastic) was significantly increased on the convex side compared to the concave side (p < 0.05). Microarray analysis showed that ERC2 and MAFB showed significantly increased gene expression on the convex side compared with those of the concave side and the neutral vertebral LF cells. These genes were significantly associated with increased expression of collagen by LF cells (p < 0.05). LF hypertrophy was identified in scoliosis patients, and the convex side was significantly more hypertrophic than that of the concave side. ERC2 and MAFB genes were associated with LF hypertrophy in patients with AIS. These phenomena are likely to be associated with the progression of scoliosis.     

DOT1L Methyltransferase Regulates Calcium Influx in Erythroid Progenitor Cells in Response to Erythropoietin

Erythropoietin (EPO) signaling plays a vital role in erythropoiesis by regulating proliferation and lineage-specific differentiation of murine hematopoietic progenitor cells (HPCs). An important downstream response of EPO signaling is calcium (Ca²⁺) influx, which is regulated by transient receptor potential channel (TRPC) proteins, particularly TRPC2 and TRPC6. While EPO induces Ca²⁺ influx through TRPC2, TRPC6 inhibits the function of TRPC2. Thus, interactions between TRPC2 and TRPC6 regulate the rate of Ca²⁺ influx in EPO-induced erythropoiesis. In this study, we observed that the expression of TRPC6 in KIT-positive erythroid progenitor cells was regulated by DOT1L. DOT1L is a methyltransferase that plays an important role in many biological processes during embryonic development including early erythropoiesis. We previously reported that Dot1l knockout (Dot1l^KO) HPCs in the yolk sac failed to develop properly, which resulted in lethal anemia. In this study, we detected a marked downregulation of Trpc6 gene expression in Dot1l^KO progenitor cells in the yolk sac compared to the wild type (WT). The promoter and the proximal regions of the Trpc6 gene locus exhibited an enrichment of H3K79 methylation, which is mediated solely by DOT1L. However, the expression of Trpc2, the positive regulator of Ca²⁺ influx, remained unchanged, resulting in an increased TRPC2/TRPC6 ratio. As the loss of DOT1L decreased TRPC6, which inhibited Ca²⁺ influx by TRPC2, Dot1l^KO HPCs in the yolk sac exhibited accelerated and sustained elevated levels of Ca²⁺ influx. Such heightened Ca²⁺ levels might have detrimental effects on the growth and proliferation of HPCs in response to EPO.     

真空高温退火对锻态Ti-6Al-4V合金显微组织与超塑性性能的影响

退火处理是改善钛合金显微组织,提高力学性能及超塑成形性能的一种重要工艺。使用真空退火炉在850℃-950℃温度区间内对锻态Ti-6Al-4V合金的进行了高温退火处理,研究了退火态Ti-6Al-4V合金微观组织演变及其在温度为900℃,应变速率为0.01 s^-1时的超塑拉伸性能。结果表明,锻态Ti-6Al-4V合金的初生α晶粒尺寸随真空退火温度的升高而减小,β相比例随真空退火温度升高而增大。当真空退火温度为910℃时,Ti-6Al-4V合金的晶粒尺寸和α相与β相分布较为均匀,其超塑拉伸试验结果表明,该合金表现出最佳的超塑拉伸性能,其拉伸延伸率达到785%,峰值应力仅为26.8 MPa。