The direct effect of carbon monoxide on KCa channels in vascular smooth muscle cells

 The vasorelaxation induced by carbon monoxide (CO) has been demonstrated previously. Both a guanosine cyclic monophosphate (cGMP) signalling pathway and cGMP-independent mechanisms have been proposed to be responsible for the vascular action of CO. A direct effect of CO on the activity of calcium-activated K (K_Ca) channels in vascular smooth muscle cells (SMCs) and the underlying mechanisms were investigated in the present study. It was found that CO hyperpolarized single SMCs isolated from rat tail arteries. The whole-cell outward K⁺ channel currents in vascular SMCs, but not in neuroblastoma cells, were enhanced by CO. Extracellularly or intracellularly applied CO increased the open probability of single high-conductance K_Ca channels concentration-dependently without affecting the single channel conductance. Although it did not increase the resting level of intracellular free calcium concentration, CO significantly enhanced the calcium sensitivity of single K_Ca channels in SMCs. Furthermore, the effect of CO on K_Ca channels was not mediated by cGMP or guanine nucleotide-binding proteins (G proteins, G_i/G_o or G_s) in excised membrane patches. Our results suggest that the direct modulation of high-conductance K_Ca channels in vascular SMCs by CO may constitute a novel mechanism for the vascular effect of CO. Received: 9 January 1997 / Received after revision: 21 February 1997 / Accepted: 10 March 1997     

肺癌组织培养液和病人血清对自身T细胞集落形成能力的影响

本文观察了10例肺癌病人围术期的肺癌组织、正常肺组织培养液和血清对自身外周血T细胞集落形成能力的影响,并以14例正常人的血清作为对照。结果显示:肺癌人病在去肿瘤负荷前T细胞集落产率为160.73±124.02/10~5,故低于正常人的397.81±133.89/10~5(P<0.001),也低于去肿瘤负荷后的(P<0.001)306.53±79.86/10~5(P<0.001)。术前病人的血清对T细胞集落的抑制率为46.97±21.42%,术后则下降至27.63±23.25%(P<0.01)。加进肺癌组织培养液时,病人的T细胞集落产率为224.83±104.05/10~5,正常肺组织培养液则为323.12±125.27/10~5(P<0.001),肺癌组织培养液和病人血清两者对T细胞集落产率的抑制性呈正相关关系(r=0.817,P<0.005)。本研究结果认为,肺癌组织能产生细胞免疫抑制物质进入血循环,导致病人T细胞集落形成能力明显下降。手术根治性切除肺癌组织,能有效地解除T细胞集落形成能力受抑制的情况。     

延髓后角脑啡肽超微结构定位和非突触部位释放——脑啡肽突触前抑制痛觉传递的形态学基础

阿片肽在后角镇痛的作用机理,被认为是通过突触前抑制一级传入纤维P物质释放的结果,然而始终未获得形态学的证实。鉴于一级传入纤维存在大量阿片受体的事实,曾提出阿片肽突触前抑制可能是通过非突触的轴-轴作用。为了验证这一设想,本文用免疫组化方法,详细观察了大鼠延髓后角浅层亮氨酸脑啡肽(L-ENK)轴突终末的突触结构和胞吐释放。电镜观察显示,延髓后角ENK终末可分为两类,第一类终末除了含圆形小清亮囊泡外,还有较多的大颗粒小泡(一般7个以上),主要分布于Ⅰ层,很少看到此类终末形成突触;第二类终末,一般含较多圆形清亮小泡和少量大颗粒小泡(一般不超过3个),它们分布于Ⅰ层和Ⅱ层,此类终末主要形成轴-树突触和少量的轴-体突触。只见到一例轴-轴突触,其突触后成分为未标记的R型终末,此外还见到ENK阳性树突成为中央终末的突触后成分。在去传入神经条件下,上述各类终末皆可见到ENK阳性大颗粒小泡的胞吐形成,它们皆位于非突触区,而在突触部位可见到清亮小泡胞吐像,上述结果提示后角ENK非突触部位释放可能是哭触后抑制一级传入纤维P物质释放的形态学基础。     

实验性犬心肌梗塞和溶栓后再闭塞时血浆中GMP—140,TXB2的变化

本文采用放免法测定实验性犬心肌梗塞和溶栓后再闭塞时血浆中ＧＭＰ－１４０、ＴＸＢ２、６－Ｋ－ＰＧＦ１α的含量变化，并探讨其与心肌梗塞溶栓后再闭塞的关系。结果表明，在血栓形成时血浆中ＴＸＡ２稳定代谢产物ＴＸＢ２水平显著升高（ｐ〈０．０５），在溶栓后再闭塞率高（８７．５％）的非治疗组（Ｂ组）。在溶栓后４小时至溶栓后３天期间呈进行性升高（ｐ〈０．０１），而在再 埘经低（１６．７％）的ＡＰＩ０１３４治疗组（     

硫代乙酰胺所致急性肝衰时内毒素血症与肝内胆汁淤积关系的研究

本实验采用硫代乙酰胺（thioacetamide，TAA）灌胃复制大鼠急性肝功能衰竭的动物模型。检测血中内毒素、转氨酶、脂蛋白-x等含量以及胆汁流量。结果表明，大鼠发生了肝内胆汁淤积与内毒素血症（ETM），并且两者呈正相关（P＜0．05）。同时肝细胞膜上Na -K -ATP酶的活力明显降低，与ETM含量呈负相关（P＜0．05）。结果提示：ETM与肝内胆汁淤积的发生有密切关系．     

胸腺细胞对胸腺止皮细胞分泌IL-6的促进作用

为分析胸腺细胞对胸腺基质细胞功能的调节作用，将胸腺细胞与小鼠胸腺上皮细胞系（ＭＴＥＣ１）共育，分析胸腺细胞对ＭＴＥＣ１分泌ＩＬ－６的影响。结果表明，胸腺细胞能明显促进ＭＴＥＣ１分泌ＩＬ－６，其促进程度与两种细胞的数量及共育时间有关。胸腺细胞（４×１０~６／孔）与ＭＴＥＣ１（１×１０~５／孔）共育４８小时，ＭＴＥＣ１分泌ＩＬ－６达高峰。去除胸腺细胞后９６小时，ＭＴＥＣ１分泌ＩＬ－６的量仍比单独培养的ＭＴＥＣＩ多１．７倍。经丝裂霉素Ｃ处理的胞腺细胞仍能促进ＭＴＥＣ１分泌ＩＬ－６，其作用程度与末经处理的胸腺细胞相似。而胸腺细胞培养上清及裂解液则不影响ＭＴＥＣ１分泌ＩＬ－６，从而证实胸腺细胞能促进ＭＴＥＣＩ分泌ＩＬ－６，其作用机制可能与细胞-细胞直接相互作用有关。     

An unusual expression of a squamous cell marker, small proline-rich protein gene, in tracheobronchial epithelium: differential regulation and gene mapping.

An unusual expression of a putative squamous cell marker, small proline-rich protein (spr1), in mucociliary epithelial cells of conducting airways was demonstrated in a serum-free culture system. A cDNA clone was isolated from the cDNA library of monkey tracheobronchial epithelial (TBE) cells by differential hybridization. This cDNA clone, MT5, exhibited 98% homology to a DNA sequence obtained from human keratinocytes treated with either UV light or phorbol esters (T. Kartasova et al., 1988, Mol. Cell. Biol. 8:2195-2230). The predicted peptide of MT5 is unusual for its high content of proline (29%), glutamine (18%), and cysteine (9%) and its repeated PKVPEPC units. The level of spr1 mRNA in cultured cells was inhibited more than 90% by vitamin A. In contrast, phorbol 12-myristate 13-acetate (PMA) stimulated the level of spr1 mRNA by 3- to 8-fold. This differential regulation coincided with the effects of these chemicals on the cornification of cultured TBE cells. Using MT5 as a probe, we have localized the tracheal spr1 gene on the human chromosome 1 by a Southern blot analysis using a panel of human-rodent somatic cell hybrid DNAs. The gene was further sublocalized to bands q22-23 by in situ hybridization.     

Cdc42 is crucial for the establishment of epithelial polarity during early mammalian development.

To study the role of Cdc42 in the establishment of epithelial polarity during mammalian development, we generated murine Cdc42-null embryonic stem cells and analyzed peri-implantation development using embryoid bodies (EBs). Mutant EBs developed endoderm and underlying basement membrane, but exhibited defects of cell polarity, cell-cell junctions, survival, and cavitation. These defects corresponded to a decreased phosphorylation and membrane localization of aPKC, a reduced phosphorylation of GSK3beta, and a diminished activity of Rac1. However, neither Rac1 nor the kinase function of GSK3beta seem to contribute to cell polarization and cell-cell contacts. In contrast, EBs expressing dominant-negative (dn) PKCzeta mimicked well the phenotype of Cdc42-null EBs, suggesting a major role of aPKC in mediating cell polarization downstream of Cdc42. Finally, aggregation experiments with endodermal cell lines suggested that Cdc42 might affect formation of adherens and tight junctions by PKCzeta-dependent regulation of the protein levels of p120 catenin and E-cadherin.