微泡在肿瘤进展的作用及其临床应用

微泡(microvesicles)能运载多种特异性蛋白、微小RNA及DNA片段,其为细胞间信号交流提供了新的途径。肿瘤细胞分泌微泡(tumor-derived membrane microvesicles,TMV),而微泡参与肿瘤进展的多个方面,TMV向周围的普通细胞传递肿瘤特异性蛋白改变细胞功能,传递microRNA改变细胞表型,增加逆转录干扰基因的稳定性,从而建立肿瘤微环境;同时,其可促进血管新生、破坏细胞基质,从而增强肿瘤细胞的侵袭性;其还可通过强化抑制性免疫T细胞的功能和诱导抗肿瘤T细胞的凋亡,参与肿瘤对机体免疫监视的逃避。另外,微泡作为肿瘤抗原递呈载体,可扩大机体的抗肿瘤免疫,而由此研制的新型肿瘤疫苗,目前已处于临床试用早期阶段。循环系统中微泡运载microRNA及DNA片段的发现,为研究无创性肿瘤标志物提供新思路。然而,微泡的分离技术有待提高,这对微泡的鉴别和亚型分类有重要意义。     

胆红素和内毒素联合作用对NRK52E细胞缝隙连接功能的影响

目的: 观察胆红素(BR)和内毒素(LPS)联合作用对肾小管上皮细胞(NRK52E)生长及细胞间缝隙连接(GJ)的影响。方法: 体外培养NRK52E细胞,不同浓度的BR和LPS联合干预,用MTT测量细胞生长;观察它们对生长融合细胞(有GJ形成)和生长未融合细胞(无GJ形成)集落形成的影响;采用细胞荧光免疫示踪法分析细胞间GJ的功能。结果: BR 从17.1 μmol/L增加至 513 μmol/L,可浓度依赖性地增加细胞生长;当BR浓度继续增加时,细胞生长逐渐降低。LPS(10-1 000 μg/L)能浓度依赖性地降低NRK52E细胞生长。 BR和LPS 联合作用下,513 μmol/L BR增加100 μg/L LPS作用下的细胞生长(P<0.05),而684 μmol/L BR降低100 μg/L LPS的细胞生长(P<0.05);513 μmol/L BR能增加100 μg/L LPS作用下GJ传递数目(P<0.05),684 μmol/L BR降低100 μg/L LPS作用下的GJ传递数目。 结论: BR和LPS联合作用时,513 μmol/L BR降低LPS的细胞毒性,684 μmol/L BR增加LPS的细胞毒性,其改变可能是通过细胞间缝隙连接发挥作用的。     

星形胶质细胞缝隙连接对缺血性脑卒中的影响

缺血性脑卒中后,半暗带区星形胶质细胞缝隙连接(GJ)仍然开放,介导细胞间的通讯,但GJ主要成分Cx43蛋白表达增多,分布改变,发生了去磷酸化及内化。本文综述了星形胶质细胞GJ对缺血性脑损伤的影响及其机制,包括星形胶质细胞GJ介导了缺血性脑损伤的扩大及其对缺血性脑损伤的保护作用。     

高校内部学术权力与行政权力制衡机制构建探索

通过分析学术权力与行政权力制衡机制存在的问题,指出构建高校内部学术权力与行政权力制衡机制的必要性;提出通过建立学术权力与行政权力分工明确、相互制衡的管理机制,实现学术权力与学术责任辨证统一,促使行政权力树立"管理就是服务"的理念,建立健全监督制约机制的措施,构建高校内部学术权力与行政权力制衡机制。     

不同β受体阻滞剂对大鼠心肌间隙连接结构作用的对比研究

目的比较三代β受体阻滞剂的代表药物卡维地洛、美托洛尔及普萘洛尔对大鼠心肌缺血再灌注损伤心肌间隙连接（GJ）结构的不同作用。方法将大鼠随机分为假手术组、缺血再灌注组、卡维地洛组、美托洛尔组及普萘洛尔组。除假手术组只穿线不结扎外,其余各组均结扎左冠状动脉前降支30min,然后松开结扎线复灌4h,建立心肌缺血再灌注损伤模型。于再灌4h末用免疫荧光和激光扫描共聚焦显微镜技术观察心肌间隙连接蛋白43（CX43）的分布及组成变化,用激光扫描共聚焦显微镜对CX43进行定量。结果与假手术组相比,缺血再灌注组CX43-GJ结构明显异常。与缺血再灌注组比较,卡维地洛组、美托洛尔组和普萘洛尔组CX43-GJ损伤减轻。各药物治疗组间比较,卡维地洛组CX43-GJ结构损伤最轻。结论各种β受体阻滞剂均具有保护心肌GJ结构的作用,以卡维地洛的作用最明显。     

Role of an alternatively spliced form of alphaII-spectrin in localization of connexin 43 in cardiomyocytes and regulation by stress-activated protein kinase

Decreases in the expression of connexin 43 and the integrity of gap junctions in cardiac muscle, induced by the constitutive activation of the c-Jun N-terminal kinase (JNK) signaling pathway, have been linked to conduction defects and sudden cardiac failure in mice [Petrich BG, Gong X , Lerner DL , Wang X , Brown JH , Saffitz JE , Wang Y. c-Jun N-terminal kinase activation mediates downregulation of connexin 43 in cardiomyocytes. Circ Res. 91 (2002) 640-647; B.G. Petrich, B.C. Eloff, D.L. Lerner, A. Kovacs, J.E. Saffitz, D.S. Rosenbaum, Y. Wang, Targeted activation of c-Jun N-terminal kinase in vivo induces restrictive cardiomyopathy and conduction defects. J. Biol. Chem. 2004;279: 15330-15338]. We examined the membrane cytoskeletal protein, alphaII-spectrin, which associates with connexin 43, to learn if changes in its association with connexin 43 are linked to the instability of gap junctions. Several forms of alphaII-spectrin are expressed in the heart, including one, termed alphaII-SH3i, which contains a 20-amino-acid sequence next to the SH3 domain of repeat 10. In adult mouse heart, antibodies to all forms of alphaII-spectrin labeled the sarcolemma, transverse ("t-") tubules and intercalated disks of cardiomyocytes. In contrast, antibodies specific for alphaII-SH3i labeled only gap junctions and transverse tubules. In transgenic hearts, in which the JNK pathway was constitutively activated, alphaII-SH3i was lost specifically from gap junctions but not from t-tubules while other isoforms of alphaII-spectrin were retained at intercalated disks. Immunoprecipitations confirmed the decreased association of alphaII-SH3i with connexin 43 in transgenic hearts compared to controls. Furthermore, activation of JNK in neonatal myocytes blocked the formation of gap junctions by exogenously expressed Cx43-GFP fusion protein. Similarly, overexpression of the SH3i fragment in the context of repeats 9-11 of alphaII-spectrin specifically caused the accumulation of Cx43-GFP in the perinuclear region and inhibited its accumulation at gap junctions. These results support a critical role for the alphaII-SH3i isoform of spectrin in intracellular targeting of Cx43 to gap junctions and implicates alphaII-SH3i as a potential target for stress signaling pathways that modulate intercellular communication.     

膝内侧稳定结构的解剖特征与软组织平衡的关系

目的:观测国人膝内侧结构解剖学特点,为膝关节置换术中内侧结构软组织平衡的松解策略选择提供形态学依据.方法:80例固定及20例新鲜成人膝关节标本,解剖观察内侧结构的组成及其位置与形态学特点.结果:膝关节内侧面支持结构包括内侧副韧带复合体和半膜肌复合体等结构,可分为3层.内侧副韧带复合体包括内侧副韧带(medial collateral ligament,MCL)深、浅两层,可分为前纵部和后斜部两部分.MCL前纵部以间接止点形式融入胫骨平台关节面下50～60 mm,鹅足深方的胫骨内侧骨面骨膜,长约92mm,中部宽约15mm后斜部纤维以腱板起于股骨内卜髁后侧,下止点弥散;在关节间隙处,后斜部纤维与其深方第3层(内侧关节囊)愈着,被半月板、冠状韧带固定.MCL深层实际上为膝内侧关节囊增厚,自股骨内上髁下半周缘骨面垂直向下走行,连接内侧半月板,止于胫骨平台内侧缘中点关节面下0.8～1.5cm骨面,并与半膜肌腱横臂融合.膝关节后内侧区域为半膜肌腱鞘和半膜肌腱的9处附丽所加强,维持膝关节后内侧角稳定.结论:基于膝关节内侧结构解剖特点,膝关节置换术中软组织平衡可以做到微创化、选择性的松解.尽量保护其结构和功能的完整对术后功能有重要意义.     

Prior information and oculomotor initiation: the effect of cues in gaps

Eye movements reflect not only an important output of various neural control systems, but also often reflect cognitive processing. For example, saccades are frequently used as a behavioural index of attentional processing. A second important eye movement type, smooth pursuit (SP), has received much less attention in this regard. These two types of eye movement were classically thought of as being separate, but recent results have suggested a closer linkage of their control mechanisms and perhaps their interactions with cognitive processes. Prior information, in the form of cues, alters saccade latency leading to characteristic cueing effects. When the period between the appearance of the cue and the appearance of the saccade target is sufficiently long, the latency of saccades to targets appearing at cued locations is increased. This "inhibition of return" is enhanced by a second type of stimulus manipulation, the early removal of the fixation target a few hundred milliseconds before the target appears (the gap paradigm). In the current experiments, the effect of cues, and interactions between cues and long gaps were investigated. In the main pursuit experiment, and in a separate saccade experiment, subjects were presented with interleaved runs of tasks with and without long gaps (gap duration = 1 s), and with and without cues. In tasks without cues, SP latency was reduced by long gaps (mean reduction 8 ms); unexpectedly, saccade latency for non-cue tasks was increased by long gaps (mean increase 41 ms). In a control experiment with only non-cue tasks, in which SP and saccade gap and non-gap tasks were run together, SP latency was again reduced in gap tasks, while saccade latency was increased, but by much less than in the first experiment. Analysis of individual subjects' data showed that while gaps increased saccade latency in two subjects who had participated in the main experiment (in which cues and gaps had been combined), in two naive subjects long gaps did not affect saccade latency. In the main pursuit experiment, cues had both spatially specific and non-spatially specific (warning) effects on pursuit latency. In non-gap conditions, latency was greater when contralateral cues were presented 250 ms prior to the appearance of the pursuit target, compared to ipsilateral cues, a pattern of effect consistent with inhibition of return. However, this was reversed when cues appeared during a gap--contralateral cues increased while ipsilateral cues decreased latency. For saccades, as expected, in both gap and non-gap conditions, cue effects were consistent with inhibition of return (latency was lower with contralateral cues), and the inhibition of return effect was larger in gap, compared to non-gap conditions. The results suggest that, in appropriate contexts (or as a result of appropriate training), there are distinct inhibitory mechanisms that operate on saccades but not pursuit. What appears to be an inhibition of return effect on pursuit latency when static cues are presented in pursuit tasks, may be better understood as the product of a modulation of mechanisms active in pursuit initiation, perhaps related to motion processing. In contrast to some recent evidence suggesting a close anatomical and functional linkage between pursuit and saccade initiation, the results are consistent with the involvement of a wider range of mechanisms, or a greater degree of flexibility, in programming the initiation of these two oculomotor behaviours.     

5-HT4 and 5-HT2 receptors antagonistically influence gap junctional coupling between rat auricular myocytes

5-hydroxytryptamine-4 (5-HT₄) receptors have been proposed to contribute to the generation of atrial fibrillation in human atrial myocytes, but it is unclear if these receptors are present in the hearts of small laboratory animals (e.g. rat). In this study, we examined presence and functionality of 5-HT₄ receptors in auricular myocytes of newborn rats and their possible involvement in regulation of gap junctional intercellular communication (GJIC, responsible for the cell-to-cell propagation of the cardiac excitation). Western-blotting assays showed that 5-HT₄ receptors were present and real-time RT-PCR analysis revealed that 5-HT_4b was the predominant isoform. Serotonin (1 μM) significantly reduced cAMP concentration unless a selective 5-HT₄ inhibitor (GR113808 or ML10375, both 1 μM) was present. Serotonin also reduced the amplitude of L-type calcium currents and influenced the strength of GJIC without modifying the phosphorylation profiles of the different channel-forming proteins or connexins (Cxs), namely Cx40, Cx43 and Cx45. GJIC was markedly increased when serotonin exposure occurred in presence of a 5-HT₄ inhibitor but strongly reduced when 5-HT_2A and 5-HT_2B receptors were inhibited, showing that activation of these receptors antagonistically regulated GJIC. The serotoninergic response was completely abolished when 5-HT₄, 5-HT_2A and 5-HT_2B were simultaneously inhibited. A 24 h serotonin exposure strongly reduced Cx40 expression whereas Cx45 was less affected and Cx43 still less. In conclusion, this study revealed that 5-HT₄ (mainly 5-HT_4b), 5-HT_2A and 5-HT_2B receptors coexisted in auricular myocytes of newborn rat, that 5-HT₄ activation reduced cAMP concentration, I_CaL and intercellular coupling whereas 5-HT_2A or 5-HT_2B activation conversely enhanced GJIC.     

声强对豚鼠下丘给声响应神经元间隔探测的影响

目的探讨声音信号强度对豚鼠下丘给声响应神经元间隔探测的影响。方法采用单细胞记录的方法,刺激信号由100 ms和50 ms白噪声相加组成,声音强度10～80 dB SPL,中间间隔时间为0、1、2、4、8、16、48、96 ms,分别统计阈响应组和阈上10,20,30 dB时,给声响应神经元的间隔阈值,并观察间隔阈值与放电率和潜伏期的关系。结果本实验共记录96个神经元,其中,给声响应神经元有35个,在阈响应强度时,给声响应神经元间隔阈值明显增大,四组强度的间隔阈值均值分别为（22.91±4.36）ms,（9.00±2.69）ms,（4.00±0.49）ms和（11.33±3.11）ms（P＆lt;0.01）,但阈上各组间的差异无统计学意义（P〉0.05）。在间隔时间为48 ms时,给声响应神经元间隔后放电恢复率的均值分别为0.44±0.15,0.83±0.12,0.88±0.07和0.61±0.10（P＆lt;0.01）。而首次放电潜伏期分别为（12.86±0.72）ms,（11.65±0.64）ms,（11.03±0.65）ms和（10.68±0.55）ms（P〉0.05）。结论声音信号强度对豚鼠下丘给声响应神经元的间隔探测有一定影响.