排序方式: 共有17条查询结果,搜索用时 171 毫秒
11.
12.
Rong Yan 《Archives of biochemistry and biophysics》2009,485(1):41-48
The membrane microparticle (MP) formation and phosphatidylserine (PS) exposure evoked by platelet activation provide catalytic surfaces for thrombin generation. Several reports have indicated the effects of cAMP-elevating agents on agonist-induced MP formation and PS exposure; however, the mechanism still remains unclear. Here we show that inhibition of basal cyclic AMP-dependent protein kinase (PKA) activity incurred platelet MP formation and PS exposure. Pretreatment of platelets with cAMP-elevating agent, forskolin, abolished thrombin plus collagen-induced MP formation and PS exposure, and obviously decreased calcium ionophore-evoked MP shedding. Moreover, the inhibitory effects of forskolin on agonists-induced MP formation and PS exposure were reversed by the PKA inhibitor H89. PKA inhibitor-induced MP formation was dose-dependently inhibited by calpain inhibitor MDL28170, and forskolin abrogated thrombin plus collagen-induced calpain activation. In conclusion, PKA plays key roles in the regulation of platelet MP formation and PS exposure. PKA-mediated MP shedding is dependent on calpain activation. 相似文献
13.
Mahajan A Naylor S Mills AD Low JC Mackellar A Hoey DE Currie CG Gally DL Huntley J Smith DG 《Cell and tissue research》2005,321(3):365-374
Lymphoid follicles cluster in the terminal rectum of various animal species and of man and hence this site may be important in the development of immune responses to pathogens. For the induction of immune responses at mucosal sites, interplay is required between various cell types performing functions ranging from antigen-sampling cells via antigen-presenting cells to antigen-specific lymphocytes. Therefore, we have characterised the cell populations and relevant functioning of follicle-associated epithelium (FAE) and associated follicles in the terminal portion of rectum in cattle as a representative mammal. Immunohistochemical studies of this region identified immune cell subsets (CD4+, CD8+, WC1+, CD2+, CD21+ and CD40+ cells) characteristic of an immune-inductive site. Examination of FAE identified a subset of cells with structural and functional features of antigen-sampling M-cells. Cells of the FAE and adjacent follicle-associated crypts expressed vimentin and a subset of these cells internalised microparticles, a further attribute of M-cells. The FAE cells were phenotypically heterogeneous and therefore the function and phenotype of these cell subsets requires further characterisation, particularly with respect to their potentially important role in the interaction of hosts with pathogens and the development of immune responses.A. Mahajan is grateful to the Darwin Trust of Edinburgh for providing post-graduate scholarship funding. This research was supported by the Department for Environment, Food and Rural Affairs, and the Scottish Executive Environment and Rural Affairs Department. 相似文献
14.
Tissue derived from embryogenic suspension cultures of cassava was bombarded with microparticles coated with a plasmid containing theuidA gene, which codes for-glucuronidase (GUS). After 3 days, the effect of different bombardment parameters was evaluated by comparing the numbers of blue spots that resulted from histological GUS assays. Counting of blue spots was performed using a system comprised of a black and white video camera, a stereoscope and a personal computer. A reproducible counting method was established by optimizing GUS assay conditions, preparation of tissue samples and acquisition of video images in view of attaining the highest possible contrast between the blue spots and the surrounding tissue. The effects of bombardment pressure, microparticle size, number of bombardments, and osmotic pretreatment on GUS expression were investigated. Optimal transient expression of theuidA gene was observed after bombardment at 1100 psi, with a particle size of 1 µm, an osmotic pretreatment and two bombardments per sample. The highest number of blue spots observed was 2400 per square centimeter of bombarded tissue. 相似文献
15.
支架内血栓形成是冠状动脉支架植入术后的重要并发症之一,尽管发生率较低,但严重者可危及生命。冠心病支架植入术后高凝状态源自患者的自身因素及支架植入所导致的一系列病理生理反应,包括斑块破裂、血管内皮损伤、组织因子大量表达、微粒生成增多等,进一步可激活血细胞和凝血系统,重者可导致局部血栓形成。及时检测及防治支架术后的高凝状态对降低支架内血栓的发生率有积极作用。本文主要对冠状动脉支架植入术后高凝状态的研究进展进行了综述。 相似文献
16.
目的:观察急性早幼粒细胞白血病(APL)细胞来源微粒(APL-MP)的促凝活性、表面组织因子(TF)表达情况、TF在其促凝活性中发挥的作用及分化治疗药物三氧化二砷(ATO)对上述指标有何影响。方法:选取3例初发APL患者,提取骨髓APL细胞,3名缺铁性贫血患者提取骨髓单个核细胞作为对照。分别用不同浓度ATO处理APL细胞24 h、48 h、72 h,收集细胞培养液提取微粒。采用流式细胞术对微粒进行定量分析并进行微粒表面TF表达情况检测;利用凝血实验比较不同组细胞释放微粒的促凝血活性;应用抗TF抗体抑制微粒促凝血活性实验检测TF在APL-MP的促凝血活性中发挥多大作用。结果:1.0μM及2.0μM ATO能显著促进APL细胞释放微粒。与正常骨髓来源单个核细胞释放的微粒相比,骨髓APL-MP的TF表达及促凝活性均显著增高,0.5μM及1.0μM ATO处理可以有效降低APL-MP的TF表达及促凝活性,且这一作用呈时间依赖性。各组APL-MP经抗TF抗体孵育后凝血时间显著延长。结论:APL-MP的TF表达和促凝学活性均显著增高,并且TF在APL-MP的促凝血活性中发挥着重要作用。ATO能显著促进APL细胞释放微粒,低浓度ATO可以有效降低APL-MP的TF表达及促凝血活性。 相似文献
17.
Various strategies have been carried out to date in order to overcome the problem of the adverse effects of bulk fungal growth in bioreactors. Nevertheless, previous conventional methods such as modifying the cultivation temperature or pH resulted in limited biomass production and consequently lower yields. In recent years microparticle enhanced cultivation (MPEC) techniques are one of the most remarkable and novel methods employed for submerged fungal production to overcome bulk microbial growth. In addition to low cost advantages, MPEC also provides benefits such as not interfering with fungal metabolism, enhancing final product concentration and improving homogeneity in the fermentation broth. In this review, a comparison of conventional and novel methods to control fungal morphology has been discussed. Additionally, the application of microparticles in fungal fermentations, their benefits to the process in terms of fungal morphology, biomass accumulation, substrate consumption, and product formation also effect mechanisms of microparticle function are discussed in detail. 相似文献