The role of cell adhesion molecules in ischemic epididymal injury

Objective The aim of this study was to investigate the role of adhesion molecules in epididymal injury induced by I–R in the rats. Study design A total of 20 male Sprague–Dawley rats were separated into two groups. A sham operation was performed in group 1 (control). In group 2 (I–R), following 6 h of unilateral spermatic cord torsion, 1-h detorsion of the testis was performed. Then, epididymides were removed to measure the tissue levels of malondialdehyde (MDA) and to make histological examination. Results MDA values increased in the group 2. In the group 2 rats demonstrated significant disorganization of the epithelium and loss of microvilli in the epididymal tissue. No abnormal microscopic findings of the epididymis of the rats in the control group. The tenascin expression in the interstitial area of the epididymis was intense in the group 2. ICAM-1 expression by intense brown staining was seen along the basement membrane in epididymal tissue from I to R group rats. The microvillus sites of the epithelia in I–R group were stained mildly by lectin. Conclusion The increased expression of adhesion molecules found in epididymal injury induced during postischemic reperfusion might implicate importance of inflammatory infiltration.     

Bimodal modulation of the botulinum neurotoxin protein-conducting channel

Clostridium botulinum neurotoxin (BoNT) is the causative agent of botulism, a neuroparalytic disease. We describe here a semisynthetic strategy to identify inhibitors based on toosendanin, a traditional Chinese medicine reported to protect from BoNT intoxication. Using a single molecule assay of BoNT serotypes A and E light chain (LC) translocation through the heavy chain (HC) channel in neurons, we discovered that toosendanin and its tetrahydrofuran analog selectively arrest the LC translocation step of intoxication with subnanomolar potency, and increase the unoccluded HC channel propensity to open with micromolar efficacy. The inhibitory profile on LC translocation is accurately recapitulated in 2 different BoNT intoxication assays, namely the mouse protection and the primary rat spinal cord cell assays. Toosendanin has an unprecedented dual mode of action on the protein-conducting channel acting as a cargo-dependent inhibitor of translocation and as cargo-free channel activator. These results imply that the bimodal modulation by toosendanin depends on the dynamic interactions between channel and cargo, highlighting their tight interplay during the progression of LC transit across endosomes.     

Single homopolypeptide chains collapse into mechanically rigid conformations

Huntington''s disease is linked to the insertion of glutamine (Q) in the protein huntingtin, resulting in polyglutamine (polyQ) expansions that self-associate to form aggregates. While polyQ aggregation has been the subject of intense study, a correspondingly thorough understanding of individual polyQ chains is lacking. Here we demonstrate a single molecule force-clamp technique that directly probes the mechanical properties of single polyQ chains. We have made polyQ constructs of varying lengths that span the length range of normal and diseased polyQ expansions. Each polyQ construct is flanked by the I27 titin module, providing a clear mechanical fingerprint of the molecule being pulled. Remarkably, under the application of force, no extension is observed for any of the polyQ constructs. This is in direct contrast with the random coil protein PEVK of titin, which readily extends under force. Our measurements suggest that polyQ chains form mechanically stable collapsed structures. We test this hypothesis by disrupting polyQ chains with insertions of proline residues and find that their mechanical extensibility is sensitive to the position of the proline interruption. These experiments demonstrate that polyQ chains collapse to form a heterogeneous ensemble of conformations that are mechanically resilient. We further use a heat-annealing molecular dynamics protocol to extensively search the conformation space and find that polyQ can exist in highly mechanically stable compact globular conformations. The mechanical rigidity of these collapsed structures may exceed the functional ability of eukaryotic proteasomes, resulting in the accumulation of undigested polyQ sequences in vivo.     

Osmolyte-induced separation of the mechanical folding phases of ubiquitin

Solvent molecules play key roles in the conformational dynamics of proteins. Here we use single molecule force-clamp spectroscopy to probe the role played by the stabilizing osmolyte glycerol on the conformational ensembles visited by a single ubiquitin protein folding after mechanical extension. Using a variety of force-pulse protocols, we find that glycerol stabilizes the native state of ubiquitin, making it more resistant to mechanical unfolding. We also find that although glycerol enhanced the hydrophobic collapse of unfolded and highly extended ubiquitins, it had no effect on the resulting collapsed states that are essential precursors of the folded state. These disparate effects of glycerol may be the result of distinct structural roles played by solvent molecules at the transition state of each folding ensemble. Our results open the way for a detailed analysis of the transition state structures that form along the folding trajectory of a mechanically extended protein.     

Discrete stack of an odd number of polarized aromatic compounds revealing the importance of net vs. local dipoles

Three polarized aromatic guest molecules (pyrene-4,5-dione, 1) form a triple-layered stack in the box-shaped cavity of an organic pillared coordination cage in water. The cavity size strictly limits the number of stacked planar guests but does not restrict guest orientation, and thus enables the study of discrete stacks of polarized guests and their preferred conformations. Crystallographic study shows that the guest molecules in the cavity are rotated 120° with respect to each other, canceling the net dipole moment rather than the local dipole moment. The unique conformation of a discrete, triple stack of 1 sharply contrasts to the standard head-to-tail conformation in infinite stacks of 1.     

大鼠主动脉内皮损伤后核因子κB活性的动态变化及血管细胞黏附分子1的表达

目的 观察动脉损伤后核因子Κb活性的动态变化,以及血管局部血管细胞黏附分子1的表达,分析二者的关系.方法 SD大鼠以球囊剥脱主动脉内皮建立大鼠动脉损伤模型.按照术后处死的时间点,将动物分为8组:0 h(对照组)、12 h、24 h、1天、2天、3天、7天及14天,每组6只.凝胶迁移率实验检测各个时间点核因子Κb活性的动态变化,免疫组织化学观察血管细胞黏附分子1在血管局部的表达.结果 术后即刻以扫描电镜观察内皮完全剥脱.术后14天可见明显的增生内膜,模型建立成功.大鼠主动脉球囊损伤后,核因子Κb在术后12 h即有明显活化,高峰在1～3天,然后逐渐下降,14天左右接近术前水平.术后即刻无血管细胞黏附分子1表达,7天时在内膜表面及少量中膜平滑肌细胞可以看到血管细胞黏附分子1表达,术后14天时在未有内皮细胞覆盖处,新生内膜的近血管腔面少量表达,而主要的 阳性转移到新生内膜近内弹力板处.结论 核因子κB和血管细胞黏附分子1参与大鼠的主动脉损伤后的炎症过程;核因子κB的活化与失活成动态变化;血管细胞黏附分子1不同时间表达在不同的部位,核因子κB的活化与失活在血管细胞黏附分子1的表达与消退之前,核因子κB对血管细胞黏附分子1的表达起调节作用.     

缺血后处理对大鼠缺血／再灌注心肌髓过氧化物酶及细胞间粘附分子的影响

目的：研究缺血后处理对大鼠缺血／再灌注心肌髓过氧化物酶（MPO）及可溶性细胞间粘附分子（sICAM）的影响。方法：选择健康SD大鼠48只,随机分为3组：假手术组、缺血再灌注组（对照组）和缺血后处理组。每组16只。制备大鼠心肌缺血再灌注模型。缺血再灌注组．收紧结扎线缺血40min,放松结扎线再灌注240min;缺血后处理组．缺血40min后．再灌注10S．缺血108,连续3个循环,然后再灌注240min;假手术组,开胸后穿线做套环,但不收紧结扎线。再灌注结束后检测血清肌酸激酶（CK）活性、sICAM含量及心肌MPO活性。结果：①血清CK活性：试验后缺血后处理组和缺血再灌注组（对照组）的CK活性明显高于假手术组[分别为（736．28±21．72）,（987．62±28．58）,（256．34±19．34）U／L,P〈0．01],缺血后处理组的明显低于对照组（P〈0．01）。②心肌MPO活性：缺血后处理组和对照组的均显著高于假手术组（P〈0．01）。缺血后处理组的较对照组显著降低[（0．86±0．08）U／G：（1．28±0．26）U／G。P〈0．01]。③血清sICAM含量：缺血后处理组和对照组血清的sICAM含量均显著高于假手术组（P〈0．01）。缺血后处理组的较对照组显著降低[（54．28±11．69）ng／ml：（76．62土13．45）ng／ml．P〈0．01]。结论：缺血后处理可减轻缺血再灌注损伤,其机制可能与减轻氧化损伤、抑制白细胞的粘附有关。     

Soluble endothelial adhesion molecules and inflammation markers in patients with β-thalassemia intermedia

The term thalassemia intermedia, indicates a clinical condition of intermediate severity between thalassaemia minor, the asymptomatic carrier, and thalassaemia major, the transfusion-dependent, severe form. Thromboembolic events frequently complicate the outcome of thalassemia intermedia patients, reflecting a hypercoagulable state to which endothelial activation is believed to play an important role. The aim of this study was to evaluate the levels of soluble endothelial adhesion molecules that reflect endothelial activation and dysfunction and levels of chronic inflammation markers in the serum of β-thalassemia intermedia patients. Thirty-five Greek patients with β-thalassemia intermedia that have received different types of treatment (Hydroxyurea, splenectomy, untreated), aged 8–63 years, were included in the study. Twenty apparently healthy individuals matched for age and sex, formed the control group. Measurements of sVCAM-1, sICAM-1, sTM, P-selectin, E-selectin and CRP levels were performed using immunoassays. We found that all endothelial adhesion molecules and CRP were significantly increased in patients (p < 0.001) and not influenced by treatment. A negative correlation was observed between levels of sICAM-1 and sTM and this finding agrees with the results of studies, which propose this correlation as a predictive marker of increased risk for vascular damage. No correlation was observed between endothelial adhesion molecules and inflammation markers. These findings support the hypothesis that a serious degree of endothelial activation and damage along with a state of chronic inflammation underlie the pathophysiology of β-thalassemia intermedia. Furthermore, these findings are of particular importance in patients who can otherwise be characterized by a subtle clinical phenotype and may have an important role in their clinical care.     

一氧化碳释放分子-2对大鼠急性坏死性胰腺炎的影响

6.9)μg/L、24.9 4-4.6、(8.7±1.5)U/g、(41.6±5.1)nmoL/mg prot、4.9±0.5(P＜0.05),而CORM-2组血清IL-10水平为(81.9±18.8)μg/L,显著高于ANP组的(52.3±14.8)μg/L(P＜0.05).结论 ANP时,应用CORM-2能够抑制系统炎症反应,减轻胰腺病理损伤,其机制可能与抑制促炎细胞因子TNF-α、IL-1的释放及上调抗炎细胞因子IL-10有关.