Ca2+-dependent cross-linking processes in human platelets

When platelet cytoplasmic Ca²⁺ is increased by the ionophore A23187 in the presence of the protease inhibitor leupeptin, there is the coincident appearance of a cross-linked polymer and the partial disappearance of monomeric protein and glycoprotein units. In the absence of leupeptin only 30% of the polymer was formed. The disappearance of monomeric protein bands, as detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis, is prevented by histamine, which as a pseudodonor amine is a known inhibitor of transglutaminase-catalyzed cross-linking. [¹⁴C]Histamine, at a tracer concentration, is incorporated into the polymer as well as into myosin, glycoproteins IIB and III, actin and tropomyosin. The lose of monomeric protein bands is mostly due to their conversion into polymers. Control measurements show that leupeptin effectively inhibited platelet Ca²⁺-dependent proteases. The cross-linking processes bringing about the observed increase in polymer formation are thus the result of a Ca²⁺-dependent platelet transglutaminase activity. The latter is located in the platelet cytosol and has been identified as platelet factor XIII on the basis of its specific cross-linking of fibrin. Platelet factor XIII, upon activation, may function physiologically to couple membrane proteins to cytoplasmic structural proteins. Thus, a new concept is proposed for the stabilization of platelet membranes and platelets as they form the hemostatic plug.     

Quantitative evaluation of temporal similarity in abundance of animal species

Summary A quantitative method is suggested for measuring the similarity of seasonal abundance patterns of different animal species. The method was applied to two sets of field data and produced biologically meaningful and interesting results.     

The Drosophila Platelet-derived Growth Factor and Vascular Endothelial Growth Factor-Receptor Related (Pvr) Protein Ligands Pvf2 and Pvf3 Control Hemocyte Viability and Invasive Migration

Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) family members are essential and evolutionary conserved determinants of blood cell development and dispersal. In addition, VEGFs are integral to vascular growth and permeability with detrimental contributions to ischemic diseases and metastatic cancers. The PDGF/VEGF-receptor related (Pvr) protein is implicated in the migration and trophic maintenance of macrophage-like hemocytes in Drosophila melanogaster embryos. pvr mutants have a depleted hemocyte population and a breakdown in hemocyte distribution. Previous studies suggested redundant functions for the Pvr ligands, Pvf2 and Pvf3 in the regulation of hemocyte migration, proliferation, and size. However, the precise roles that Pvf2 and Pvf3 play in hematopoiesis remain unclear due to the lack of available mutants. To determine Pvf2 and Pvf3 functions in vivo, we generated a genomic deletion that simultaneously disrupts Pvf2 and Pvf3. From our studies, we identified contributions of Pvf2 and Pvf3 to the Pvr trophic maintenance of hemocytes. Furthermore, we uncovered a novel role for Pvfs in invasive migrations. We showed that Pvf2 and Pvf3 are not required for the directed migration of hemocytes, but act locally in epithelial cells to coordinate trans-epithelial migration of hemocytes. Our findings redefine Pvf roles in hemocyte migration and highlight novel Pvf roles in hemocyte invasive migration. These new parallels between the Pvr and PDGF/VEGF pathways extend the utility of the Drosophila embryonic system to dissect physiological and pathological roles of PDGF/VEGF-like growth factors.     

不同剂量熊果酸干预糖尿病小鼠视网膜病变的作用及机制研究

目的:探究不同剂量熊果酸(UA)干预糖尿病小鼠视网膜病变的作用及机制。方法:选取雄性健康C57BL/6小鼠60只,其中50只按50 mg/kg的剂量一次性往小鼠尾静脉注射新鲜配置的四氯嘧啶生理盐水溶液构建小鼠糖尿病视网膜病变模型,随机分为5组,每组10只,分别为模型组、阳性对照组(小鼠玻璃体注射3μL 40 mg/m L的曲安奈德),低剂量UA干扰组(小鼠玻璃体注射3μL剂量为0.5μg/μL的UA)、中剂量UA干扰组(小鼠玻璃体注射3μL剂量为1.0μg/μL的UA),高剂量UA干扰组(小鼠玻璃体注射3μL剂量为2.0μg/μL的UA),余下10只小鼠作为正常对照组。观察各组小鼠对胰岛素敏感性、视网膜内糖代谢情况、小鼠视网膜神经节细胞(RGCs)凋亡情况,比较各组小鼠视网膜组织中血管内皮生长因子(VEGF)、环氧化酶-2(COX-2)、基质金属蛋白酶2(MMP-2)蛋白及其mRNA的表达情况。结果:建模后,正常对照组胰岛素抵抗指数(HOMA-IR)、视网膜含糖量、葡萄糖转运体-1(GLUT-1)与葡萄糖转运体-3(GLUT-3)含量、RGCs凋亡率、视网膜组织中VEGF、COX-2、MMP-2蛋白及其mRNA的表达量低于模型组(P0.05);经干扰后,阳性对照组、不同剂量UA干扰组HOMA-IR、视网膜含糖量、GLUT-1、GLUT-3的含量、RGCs凋亡率、视网膜组织中VEGF、COX-2、MMP-2蛋白及其mRNA的表达量低于模型组(P0.05),且随UA干扰剂量的升高而降低(P0.05)。结论:UA能够降低HOMA-IR和视网膜糖代谢能力,抑制RGCs的凋亡,对VEGF、COX-2、MMP-2蛋白及其mRNA的表达具有一定的抑制作用,高剂量UA对糖尿病小鼠视网膜病预防治疗效果较好。     

Orally bioavailable amine-linked macrocyclic inhibitors of factor XIa

The discovery of orally bioavailable FXIa inhibitors has been a challenge. Herein, we describe our efforts to address this challenge by optimization of our imidazole-based macrocyclic series. Our optimization strategy focused on modifications to the P2 prime, macrocyclic amide linker, and the imidazole scaffold. Replacing the amide of the macrocyclic linker with amide isosteres led to the discovery of substituted amine linkers which not only maintained FXIa binding affinity but also improved oral exposure in rats. Combining the optimized macrocyclic amine linker with a pyridine scaffold afforded compounds 23 and 24 that were orally bioavailable, single-digit nanomolar FXIa inhibitors with excellent selectivity against relevant blood coagulation enzymes.     

碱性成纤维细胞生长因子对激光烧伤大兔皮肤愈合的影响分析

摘要 目的：探讨碱性成纤维细胞生长因子对激光烧伤大兔皮肤愈合的影响分析。方法：通过热辐射仪激光灼烧对大兔耳朵进行烧伤处理,根据实验需求,将其随机分为三组：对照组,bFGF组,bFGF + DAPT组。通过ImageJ软件测量伤口面积和疤痕组织的厚度,并定期计算残余伤口面积率和疤痕指数。通过组织学分析大兔伤口愈合的新血管生成量。通过蛋白印迹分析Notch1、Jagged1和Hes1的蛋白表达。通过免疫荧光分析愈合后的皮肤中α-SMA,Col I和Col III的相对蛋白水平。结果：bFGF组较对照组的疤痕指数降低（P<0.05）,bFGF+DAPT组较bFGF组疤痕指数升高（P<0.05）。bFGF组较对照组的愈合面积增加（P<0.05）,bFGF + DAPT组较bFGF组愈合面积降低（P<0.05）。与对照组相比,bFGF组的愈合时间明显缩短,较低的残余伤口面积和较低的疤痕指数（P<0.05）,而bFGF + DAPT组表现出明显的愈合延迟和较高的疤痕指数（P<0.05）。bFGF组较对照组的新血管生成量增加（P<0.05）,bFGF + DAPT组较bFGF组心血管生成量减少（P<0.05）。bFGF组较对照组的肉芽组织平均厚度增加,表皮间隙的闭合百分比升高（P<0.05）,bFGF + DAPT组较bFGF组肉芽组织平均厚度增加、表皮间隙的闭合百分比减少（P<0.05）。H＆E染色进行组织学分析发现,与对照组和bFGF + DAPT组相比,bFGF组出现明显的再上皮化和新血管形成,愈合效率较高（P<0.05）。bFGF组较对照组Notch1、Jagged1和Hes1的蛋白表达升高（P<0.05）,bFGF + DAPT组较bFGF组Notch1、Jagged1和Hes1的蛋白表达降低（P<0.05）。bFGF组较对照组?琢-SMA,Col I和Col III的蛋白表达降低（P<0.05）,bFGF + DAPT组较bFGF组表达升高（P<0.05）。结论：bFGF可以通过促进ESC的增殖并通过激活Notch1 / Jagged1途径抑制其向肌成纤维细胞（Myofibroblasts,MFB）的分化加快伤口愈合,减少疤痕形成。     

Periostin Mediates the Increased Pro‐Angiogenic Activity of Gastric Cancer Cells under Hypoxic Conditions

This study was conducted to investigate the biological role of periostin in gastric cancer (GC) under hypoxia. Western blot analysis revealed that along with an upregulation of hypoxia‐inducible factor‐1alpha, there was a time‐dependent induction of periostin in MKN‐45 cells under hypoxia (2% O₂), increasing by eightfold as compared to normoxic cells. Pretreatment with 30 µM PD98059, an inhibitor of ERK1/2, significantly reduced hypoxia‐stimulated periostin expression (P < 0.01). Periostin knockdown in MKN‐45 cells was achieved by specific small interfering RNA (siRNA). The conditioned medium from periostin siRNA‐transfected MKN‐45 cells induced significantly less (P < 0.01) endothelial tube formation than control siRNA‐transfected cells. Additionally, periostin silencing markedly decreased the mRNA expression and secretion of vascular endothelial growth factor (VEGF) in hypoxic MKN‐45 cells. Thus, our data suggest that periostin is a hypoxia‐response gene and mediates a cross talk between GC and endothelial cells under hypoxia, partially through regulation of the VEGF expression. © 2013 Wiley Periodicals, Inc. J BiochemMol Toxicol 27:364‐369, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21498     

Phospholipase A2 from Trypanosoma brucei gambiense and Trypanosoma brucei brucei: Inhibition by Organotins

Activity and kinetics of phospholipase A₂ (PLA₂) from Trypanosoma brucei gambiense (Wellcome strain) and Trypanosoma brucei brucei (GUTat 3.1) were examined using two different fluorescent substrates. The activity in the supernatants of sonicated parasites was Ca²⁺-independent, strongly stimulated by Triton X-100 with optimum activity at 37°C and pH 6.5–8.5. To encourage a possible interaction between the parasite enzyme and organotin compounds, fatty acid derivatives of dibutyltin dichloride were synthesized and evaluated as potential inhibitors of PLA₂. The enzyme from the two-trypanosome species differ with respect to kinetic parameters and are noncompetitively inhibited by the organotin compounds. The Michaelis constant (K_M) for PLA₂ from T. b. brucei is 63.87 and 30.90 μM while for T. b. gambiense it is 119.64 and 32.90 μM for the substrates l,2-bis-(1-pyrenebutanoyl-sn-glycero-3-phosphocholine (PBGPC) and 2-(12-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dode-canoyl-1-hexadecanoyl-sn-glycero-3-phosphocholine (NBDC₁₂-HPC), respectively.     

Stem cells: Insights into the secretome

Stem cells have been considered as possible therapeutic vehicles for different health related problems such as cardiovascular and neurodegenerative diseases and cancer. Secreted molecules are key mediators in cell–cell interactions and influence the cross talk with the surrounding tissues. There is strong evidence supporting that crucial cellular functions such as proliferation, differentiation, communication and migration are strictly regulated from the cell secretome. The investigation of stem cell secretome is accumulating continuously increasing interest given the potential use of these cells in regenerative medicine. The scope of the review is to report the main findings from the investigation of stem cell secretome by the use of contemporary proteomics methods and discuss the current status of research in the field. This article is part of a Special Issue entitled: An Updated Secretome.