视网膜色素上皮细胞吞噬纤维连接蛋白时细胞内信号传导通路的研究

目的 探讨视网膜色素上皮（retinal pigment epithelium PRE)细胞对纤维连接蛋白（fibronectin,FN）的吞及相关细胞内信号传导通路的作用。方法 以FN包被的聚苯乙烯微球（微球）作为吞噬标记物, 建立人胎儿RPE细胞吞噬模型。所研究的细胞内信号传导通路包括蛋白激酶C（protein kinase C,PKC)通路、酪氨酸激酶（tyrosine kinase,TK）通路和磷酯酰肌醇3－激酶（phosphatidylinositol 3-kinase,PI3-K)通路,分别使用这3种信号通路的抑制剂预处理RPE细胞,37℃吞噬3h,流式细胞仪定量检测吞噬指数。结果 与对照组比较,RPE细胞对FN包被微球有明显吞噬作用（P＜0．05）。PKC抑制剂PMA（phorbol 12-myristate 13-acetate,100nmol/L)或Calphostin C(400nmol/L)非特异性地增加了PRE细胞对FN包被或未包被微球的吞噬指数（P＜0．01）;TK和PI3K的抑制剂Genistein(100μg/ml）与Wortmannin(5μmol/L）分别降低了FN包被微球的吞噬指数（P＜0．001）,但对对照组无影响。联合使用不同抑剂Genistein或Wortmannin可对抗PMA对FN吞噬的增强作用,但二者联合使用则具有相累加的抑制吞噬作用。结论 PRE细胞对FN的吞噬受细胞内PKC、TK和PI3－K信号传导通路的调节,此结论将为进一步研究治疗增殖性玻璃体视网膜病变的药物提供理论依据。     

The effects of stimulating protease-activated receptor-1 and -2 in A172 human glioblastoma

Summary. Human glioblastoma cell line A172 expressed protease-activated receptor-1 and -2 (PAR-1 and PAR-2). We investigated the effects of the stimulation of these receptors by receptor-activating agonist peptides on the Ca²⁺ signaling, protein kinase C translocation, cell morphology and cell proliferation in A172. Both PAR-1 agonist SFLLRN and PAR-2 agonist SLIGKV induced an increase in [Ca²⁺]i. The prior treatment of A172 with PAR-2 agonist SLIGKV did not influence the [Ca²⁺]i response to PAR-1 agonist SFLLRN or thrombin, however, the prior treatment with PAR-1 agonist SFLLRN or thrombin completely abolished the second response to PAR-2 agonist SLIGKV. Treatment with each agonist peptide produced thinner and fewer processes in A172. The PAR-2 agonist inhibited the proliferation of A172 significantly while PAR-1 agonist did not. PKC-α and γ were translocated from cytosol to membrane with either PAR-1 or PAR-2 stimulation, however, ι was specifically translocated with SFLLRN, and λ with SLIGKV, respectively. These results indicated that PAR-1 and PAR-2 stimulation produced a similar [Ca²⁺]i response and morphological changes in A172 glioblastoma while the effects on the cell proliferation and activation of PKC isozymes were distinct, suggesting that different signal transduction pathways were activated by these receptors. The uni-directional cross desensitization implies a functional linkage between PAR-1 and PAR-2 receptors. Received May 23, 2000; accepted September 13, 2000     

CD19 regulates intrinsic B lymphocyte signal transduction and activation through a novel mechanism of processive amplification

The fate of B lymphocytes is dependent on intrinsic and B cell antigen receptor (BCR)-induced signals. These signals are interpreted and modified by response regulators such as CD19 that govern mature B cell activation. The current understanding of how CD19 governs B lymphocyte signaling is outlined in this review. Primarily, CD 19 establishes a novel Src-family kinase amplification loop that regulates basal signal transduction thresholds in resting B cells. Moreover, CD19 amplifies Src-family kinase activation following BCR ligation. CD19 amplification of Lyn activity leads to processive phosphorylation of CD19 and downstream substrates including CD22. Phosphorylated CD19 recruits other effector molecules including Vav, Grb2, phosphoinositide 3-kinase, phospholipase C γ2, and c-Abl, which may contribute to CD19 regulation of B cell function. CD19/Lyn complex formation also regulates phosphorylation of CD22 and FcγRIIB, which inhibit B cell signal transduction through the recruitment of the SHP1 and SHIP phosphatases. These observations provide insight into how CD19 governs the molecular ordering and intensity of signals transduced in B cells, and how perturbations in CD19 expression or signaling function may contribute to autoimmunity.     

Mechanical trauma induces rapid astroglial activation of ERK/MAP kinase: Evidence for a paracrine signal

Astrogliosis is a prominent and ubiquitous reaction of astrocytes to many forms of CNS injury, often implicated in the poor regenerative capacity of the adult mammalian CNS. Transmembrane signals that rapidly trigger and maintain astroglial responses to injury are largely undefined. Several candidate inducers of astrogliosis, including growth factors and neuropeptides, act via the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway. We previously observed chronically activated ERK/MAPK in human reactive astrocytes. To investigate mechanisms of pathway activation in a defined in vitro model, primary cultured astroglial monolayers were subjected to focal mechanical injury. Within 2-10 min, ERK/MAPK was activated, but only in cells near the wound edge. By 30 min, the entire monolayer showed activation, which persisted for 4 to 8 h. ERK/MAPK activation was specifically blocked by application of the MEK inhibitors, PD98059 and U0126. Cell-cell contact was not necessary for intercellular spread of ERK/MAPK activation, and ERK/MAPK-stimulating activity was found in the injury-conditioned medium. The activating factor was shown to have a native size of 50-100 kD and did not signal through the classical EGF receptor. Injury-induced signaling to ERK/MAPK required Ras, as demonstrated by specific blockade after transient transfection with a dominant negative Ha-RasN17 construct. Finally, we demonstrated that focal lesioning of adult rat cortex induces a rapid activation and spreading of astroglial ERK/MAPK, suggesting that similar mechanisms may operate in astroglial activation following acute brain injury.     

5/6肾切除大鼠早期模型中p38MAPK的动态变化

目的：研究5/6肾切除大鼠模型中p38MAPK磷酸化的动态表达情况。方法：82只雄性SD大鼠分为两组：5/6肾切除模型组72只,假手术对照组10只。模型组造模完成后,分别于肾切除早期（术后1/2h、1h、3h、6h、12h、1d、2d、4d）相应时间点处死,每组9只,假手术组于术后12h处死,称量各组体重及残余肾重,计算肥大指数;下腔静脉取血留取血清测定血肌酐（Scr）、尿素氮（BUN）;以Western blotting免疫印迹法检测肾皮质磷酸化p38MAPK活性的表达情况;以病理光镜和电镜观察肾小球、肾小管及肾间质组织形态学及超微结构的变化。结果：模型组与对照组相比,肾脏呈代偿性肥大,肥大指数增高（P〈0.05）,Scr和BUN升高（P均〈0.01）。免疫印迹法显示5/6肾切除术后1/2h、1h、3h、6h、12h磷酸化p38信号呈递增趋势,尤以12h信号最强,之后信号减弱,2d时几乎不可见,4d有较弱的信号,假手术组未见明显信号。光镜下,发现肾小球有轻度系膜细胞增生,基质增宽不明显,肾小管偶有轻度变性,间质偶有炎性细胞浸润。电镜下,偶见足突局灶融合。结论：5/6肾切除大鼠在造模完成后12h时磷酸化p38MAPK表达最强。     

颈椎单开门扩大成形术后脊髓信号强度变化作用的临床观察

目的探讨颈脊髓压迫性病变中MRI髓内信号强度的改变与临床症状及疾病预后的关系。方法对选取的46例颈脊髓压迫性病变的病人进行多因素分析。结果术前正常信号/正常信号(N/N)组有13例,正常信号/高信号(N/Hi)组有26例,纯信号/高信号(Lo/Hi)组有7例。随访时Lo/Hi组恢复率明显低于其他两组,术前脊髓最大受压处的横截面积在N/N组、N/Hi与Lo/Hi组之间差异显著,术后JOA评分3组之间也有差异。结论脊髓受压后出现的髓内信号强度的改变,多表现为T2加权序列高信号,单独出现预示脊髓有一定的修复功能,但如同时出现T1加权序列改变则预后不良。     

亚溶量C5b-9与足细胞损伤及其信号传导的研究进展

膜性肾病的发病机制与亚溶量C5b-9(SC5b-9)诱导足细胞损伤有关.SC5b-9刺激足细胞产生的氧化剂、蛋白酶、前列腺素类、细胞外基质及各种细胞因子对足细胞有损伤作用.SC5b-9对足细胞的作用主要表现为引起足细胞凋亡、足细胞脱落以及对细胞周期的影响.MAPK通路在SC5b-9导致足细胞损伤中起到重要的作用.     

腹腔镜下幽门环肌切开术对患儿细胞免疫的影响

目的探讨腹腔镜下幽门环肌切开术围手术期CO2气腹对患儿细胞免疫的影响及临床意义。方法选择40例先天性肥厚性幽门狭窄患儿，随机分为腹腔镜组和开腹组，分别于术前及术后1d、3d监测围手术期CD3、CD4、CD4／CD8的变化。结果开腹组CD4术后1d轻微下降，术后3d明显升高，术后1d与3d比较，差异有显著统计学意义（P=0．007）；开腹组CD4／CD8术后1d下降，与术前比较，差异有统计学意义（P=0．044）；术后3d升高，与术后1d比较，差异有显著统计学意义（P=0．003）。腹腔镜组CD4术后1d下降，与术前比较，差异有显著统计学意义（P=0．023），术后3d明显升高，与术前比较，差异无统计学意义（P=0．596）；两组比较CD4／CD8腹腔镜组较高，差异有显著性（F=3．961，P〈0．05）结论新生儿及婴儿腹腔镜手术可引起机体免疫功能的改变，腹腔镜组对机体免疫功能的影响较小。