Intimal hyperplasia and hemodynamic factors in arterial bypass and arteriovenous grafts: a review

Stenosis at the graft–vein junction caused by intimal hyperplasia (IH) is the major cause of failure of vascular access grafts used for hemodialysis. There is a strong relationship between hemodynamic factors and formation of IH. The hemodynamic pattern and the location of IH are different in arterial bypass grafts (ABGs) compared with arteriovenous grafts (AVGs). In an ABG, end-to-side anastomosis of the expanded polytetrafluoroethylene graft and artery produces hemodynamic changes around the junction. IH develops at the arterial floor and the toe and heel of the distal anastomosis. Low shear stress and oscillating shear forces at the arterial floor and the heel plus a high wall sheer stress (WSS) gradient at the toe probably promote IH development. Compliance mismatch between the graft and artery causes turbulence that may contribute to IH formation. The blood flow rate in AVGs is 5–10 times greater than that in ABGs. High flow causes turbulence that injures endothelial cells and eventually results in IH. The peak WSS in AVGs is about 6N/m², much higher than that in ABGs. Excessively high WSS may effect IH formation in AVGs. Several venous cuff or patch anastomotic designs have been used in attempts to regulate hemodynamic factors in grafts. In ABGs, these designs appear to help decrease IH formation. In AVGs, however, they generally have not improved patency rates. In a high-flow system such as an AVG, more drastic changes in anastomotic design may be required.     

Bruch''s membrane of the brachymorphic mouse

Bruch's membrane exists between the retinal pigment epithelium and the choriocapillary endothelium. Its structure is very complicated, having five sublayers containing basement membranes of retinal pigment epithelium and choriocapillary endothelium, outer and inner collagenous layers, and a central elastic layer. In the development of Bruch's membrane in normal mice, both basement membranes are created first. Secondarily, collagen fibers are accumulated in the space between these basement membranes and then form a collagenous layer. Finally, the elastic layer elaborated in the collagenous layer separates this into outer and inner collagenous layers. Brachymorphic mice have a disorder in the sulfation pathway, resulting in undersulfation. Consequently, in Bruch's membrane of brachymorphic mice, the expression of decorin, a small proteoglycan containing chondroitin sulfate and an indispensable component in collagen assembly, is at a very low level. It is clear that hypoplasia of the collagenous layer in Bruch's membrane of brachymorphic mice induces a disorder in the following formation of the elastic layer. These findings suggest that the formation of the collagenous layer, regulated with acidic glycoconjugates such as decorin, is important in the development of Bruch's membrane.     

H2O2对大鼠骨骼肌卫星细胞凋亡和线粒体膜电位的影响及EPO的保护作用

目的: 探讨过氧化氢(H2O2)对大鼠骨骼肌卫星细胞(SMSC)凋亡和线粒体膜电位(MMP)的影响以及促红细胞生成素(EPO)的保护作用。方法: 取体外培养的骨骼肌卫星细胞,随机分为正常对照组、H2O2组、H2O2+EPO组,采用流式细胞仪(FCM)检测细胞凋亡率和MMP的平均荧光强度,Hoechst 33258染色后荧光显微镜观察凋亡细胞的形态学变化。结果: H2O2组凋亡发生率最高,为(22.13±1.79)%,经10、20、40 kU/L浓度的EPO预处理后凋亡率分别为(16.47±2.53)%、(4.97±0.55)%、(2.93±0.47)%;H2O2干预组MMP最低,为9.70±0.09,经10、20、40 kU/L浓度的EPO预处理后MMP分别为12.67±0.32、27.90±0.66、44.53±0.93,对照组凋亡率为(1.93±0.57)%,MMP为51.37±0.64;在H2O2干预组和低剂量EPO预干预组,Hoechst 33258染色呈现明显的凋亡征象。结论: EPO可抑制H2O2诱导的细胞凋亡并稳定线粒体膜电位。     

Plectin deficiency leads to both muscular dystrophy and pyloric atresia in epidermolysis bullosa simplex

Plectin is a cytoskeletal linker protein which has a long central rod and N‐ and C‐terminal globular domains. Mutations in the gene encoding plectin (PLEC) cause two distinct autosomal recessive subtypes of epidermolysis bullosa: EB simplex (EBS) with muscular dystrophy (EBS‐MD), and EBS with pyloric atresia (EBS‐PA). Previous studies have demonstrated that loss of full‐length plectin with residual expression of the rodless isoform leads to EBS‐MD, whereas complete loss or marked attenuation of expression of full‐length and rodless plectin underlies the more severe EBS‐PA phenotype. However, muscular dystrophy has never been identified in EBS‐PA, not even in the severe form of the disease. Here, we report the first case of EBS associated with both pyloric atresia and muscular dystrophy. Both of the premature termination codon‐causing mutations of the proband are located within exon 32, the last exon of PLEC. Immunofluorescence and immunoblot analysis of skin samples and cultured fibroblasts from the proband revealed truncated plectin protein expression in low amounts. This study demonstrates that plectin deficiency can indeed lead to both muscular dystrophy and pyloric atresia in an individual EBS patient. © 2010 Wiley‐Liss, Inc.     

T and B cells target identical regions of the non-collagenous domain 1 of type VII collagen in epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita (EBA) is a severe immunobullous disease and is caused by IgG against type VII collagen (Col VII) of anchoring fibrils. In this study, utilizing ELISA and immunoblot, 13/15 EBA sera but 0/20 bullous pemphigoid sera and 0/30 healthy control sera showed IgG reactivity with distinct recombinant subregions of the non-collagenous domain 1 (NC1) of Col VII. In two EBA patients, IgG titers against Col VII-NC1 were grossly correlated to clinical disease activity. Moreover, Col VII-reactive T cells were identified in a representative EBA patient which recognized identical subdomains of Col VII-NC1. These findings strongly suggest that (1) the Col VII-NC1 ELISA is a powerful tool for making the diagnosis of EBA, (2) Col VII-specific IgG grossly relates to disease activity and (3) IgG reactivity is associated with T cell recognition of identical subdomains of Col VII-NC1.     

Amyotrophic lateral sclerosis mutant vesicle-associated membrane protein-associated protein-B transgenic mice develop TAR-DNA-binding protein-43 pathology

Cytoplasmic ubiquitin-positive inclusions containing TAR-DNA-binding protein-43 (TDP-43) within motor neurons are the hallmark pathology of sporadic amyotrophic lateral sclerosis (ALS). TDP-43 is a nuclear protein and the mechanisms by which it becomes mislocalized and aggregated in ALS are not properly understood. A mutation in the vesicle-associated membrane protein-associated protein-B (VAPB) involving a proline to serine substitution at position 56 (VAPBP56S) is the cause of familial ALS type-8. To gain insight into the molecular mechanisms by which VAPBP56S induces disease, we created transgenic mice that express either wild-type VAPB (VAPBwt) or VAPBP56S in the nervous system. Analyses of both sets of mice revealed no overt motor phenotype nor alterations in survival. However, VAPBP56S but not VAPBwt transgenic mice develop cytoplasmic TDP-43 accumulations within spinal cord motor neurons that were first detected at 18 months of age. Our results suggest a link between abnormal VAPBP56S function and TDP-43 mislocalization.     

不同分期特发性黄斑裂孔玻璃体切除联合内界膜剥离术治疗效果分析

目的总结分析不同Gass分期特发性黄斑裂孔（idiopathicmacularhole,IMH）患者行玻璃体切除联合内界膜剥离手术结果,探讨IMH手术时机选择。方法回顾分析2006年1月至2009年12月在我院接受玻璃体切除联合内界膜剥离的IMH47例（48眼）,术后随访6个月以上,用光学相干断层扫描（opticalcoherencetomography,OCT）观察术前、术后黄斑裂孔,统计术前、术后最佳矫正视力（bestcorrectedvisualacuity,BCVA）,对结果进行统计分析。结果①根据Gass分期,Ⅱ期10眼、Ⅲ期20眼、Ⅳ期18眼,随着IMH分期进展,裂孔逐渐增大,术前BCVA逐渐下降,Ⅲ、Ⅳ期IMH直径显著大于Ⅱ期IMH,P〈0．01,但Ⅲ、Ⅳ期IMH直径之间无显著性差异;术前BCVA与Gass分期之间呈负相关关系,r=0．42,P〈0．05。②93．75％（45／48眼）IMH术后经OCT证实完全闭合,6．25％（3／48眼）IMH术后随访超过6个月始终未闭合,但孔径均较术前有所缩小。85．42％（41／48眼）术后BCVA提高,其余14．58％（7／48眼）术后BCVA无明显改变,无术后视力下降者。术后BCVA与术前相比明显提高,P〈0．01。③随着IMH分期进展,IMH术后裂孔闭合率逐渐下降,分别是100％、95％和88．89％,但各组间无显著差异,P〉0．05;3组术后视力提高率分别是90％、90％、77．89％,无显著差异,P〉0．05;三组病例术后BCVA均明显高于同组术前,各组P〈0．01。术后BCVA与Gass分期之间呈负相关关系,r=0．45,P〈0．05。结论IMH是进行性恶化性疾病,玻璃体切除联合内界膜剥离术是治疗IMH的有效手术方法,对Ⅱ期以上IMH应尽早手术治疗,对Ⅳ期以上的晚期IMH,手术仍有积极意义。     

Epstein-Barr virus (EBV) latent membrane protein-1-specific cytotoxic T lymphocytes targeting EBV-carrying natural killer cell malignancies

Epstein-Barr virus (EBV)-encoded latent membrane protein (LMP) 1 is a potential target for immunotherapy of some proportion of Hodgkin's disease cases, nasopharyngeal carcinomas, EBV-associated natural killer (NK)/T lymphomas, and chronic active EBV infection (CAEBV). Since it is unknown whether EBV-infected NK/T cells are susceptible to lysis by LMP1-specific cytotoxic T lymphohcytes (CTL), we here tested the ability of mRNA-transduced antigen-presenting cells (APC) to stimulate rare LMP1-specific CTL. A 43-amino acid N-terminal deletion mutant LMP1 (DeltaLMP1) could be efficiently expressed in dendritic cells and CD40-activated B cells upon mRNA electroporation. DeltaLMP1-expressing APC were found to stimulate LMP1-specific CTL from a healthy donor and a CTL clone recognized a peptide, IIIILIIFI, presented by HLA-A*0206 molecules. Processing and presentation of the antigenic peptide proved dependent on expression of an immunoproteasome subunit, low-molecular-weight protein-7, as confirmed by RNA interference gene silencing. Furthermore, an EBV-infected NK cell line derived from a patient with CAEBV, and another from an NK lymphoma with enforced HLA-A*0206 expression, were specifically lysed by the CTL. Overall, these data suggest that immunotherapy targeting LMP1 in EBV-associated NK lymphomas and CAEBV might serve as an alternative treatment modality.     

Human papillomaviruses bind a basal extracellular matrix component secreted by keratinocytes which is distinct from a membrane-associated receptor

Human papillomaviruses (HPVs) have previously been shown to adsorb to cultured cells via membrane-associated heparan sulfate (HS) and alpha6 integrin. We demonstrate that cultured keratinocytes uniquely secrete a component into the basal extracellular matrix (ECM) which can function to adsorb HPV particles which can then be internalized by adherent cells. This uncharacterized basal ECM adsorption receptor was secreted by normal human epidermal keratinocytes (NHEK) and by each of the four keratinocyte-derived cell lines we examined, but not by non-keratinocyte cell lines. Multiple HPV types bound preferentially to this keratinocyte-specific receptor over the membrane-associated receptor, and binding to the basal ECM adsorption receptor was refractory to inhibition by heparin. Like the membrane-associated receptor, this basal ECM component was functional as an adsorption receptor in our in vitro infection model using HPV-11. Unlike particle adsorption, however, successful infection with HPV-11 virions remained sensitive to the pretreatment of virions with heparin. The secreted basal ECM receptor did not colocalize with antibodies against HS, perlecan, or alpha6 integrin, but colocalized with antibody against laminin-5, a marker of keratinocyte ECM and an abundant component of the basement membrane in mucosa and skin. These findings suggest a model for natural infections in which HPV virions, nonspecifically adsorbed to HS on suprabasal keratinocytes throughout an epithelial wound, might be transferred to mitotically active migrating keratinocytes via an intermediate association with the ECM secreted by these cells as they reestablish the basement membrane.     

A critical role for vesicle-associated membrane protein-7 in exocytosis from human eosinophils and neutrophils

BACKGROUND: Granulocyte exocytosis is proposed to be critically dependent on the interaction of soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptors (SNAREs) located on granules/vesicles (v-SNAREs) and plasma membrane (t-SNAREs). Previous studies indicated that the v-SNARE, vesicle-associated membrane protein (VAMP)-2, as well as t-SNAREs (SNAP-23, syntaxin-4 and -6) are implicated in exocytosis from human granulocytes. Vesicle-associated membrane proteins-7 and -8 have been implicated in endosome/lysosome trafficking, however, their role in granulocyte exocytosis remains obscure. OBJECTIVE: We sought to investigate the expression and functional role of SNARE isoforms in the secretion of different granule-derived mediators in human eosinophils and neutrophils. METHODS: The expression of SNAREs was determined by subcellular fractionation and flow cytometry. SNARE-specific antibodies were examined for their ability to impair mediator release from permeabilized eosinophils and neutrophils. RESULTS: Vesicle-associated membrane proteins-7 and -8 were localized to granule and membrane-enriched fractions in eosinophils and neutrophils, whereas syntaxin-6 was not detectable. In permeabilized cells, anti-VAMP-7, but not anti-VAMP-8, antibody impaired the secretion of all mediators examined (in eosinophils, eosinophil peroxidase and eosinophil-derived neurotoxin; in neutrophils, myeloperoxidase, lactoferrin and matrix metalloprotease-9) in a dose-dependent manner. In contrast, anti-VAMP-2 modestly and selectively impaired secretion from small granules and vesicles. Syntaxin-4, but not syntaxin-6, was found to interact with SNAP-23 and was partially involved in mediator secretion from multiple compartments. CONCLUSION: Our observations indicate for the first time a critical role for VAMP-7 in both eosinophil and neutrophil mediator release.