Immunochemical characterization of mouse brain-associated theta (Thy-1) antigen.

The Thy-1 antigens or rat brain and thymus have been isolated and chemically characterized, but those of mice have not been identified. Moreover, it is uncertain whether the antigens are glycolipids or glycoproteins. This study with highly purified preparations of gangliosides GM₁, ¹GD_1a, GD_1b and GT_1b from bovine brain and several ganglioside fractions from mouse brain showed that Thy-1 activity does not reside in gangliosides, but rather in the chloroform-methanol-insoluble residue of brain remaining after extraction of gangliosides. The antigen could be solubilized from this residue with a non-ionic detergent. The antigenic activity of the solubilized preparation was heat-labile but resistant to periodate. The chemical properties of the Thy-1 antigen of mouse brain are discussed.     

Fibronectin activates matrix metalloproteinase-9 secretion via the MEK1-MAPK and the PI3K-Akt pathways in ovarian cancer cells

Cell adhesion to the extracellular matrix appears to trigger a cascade of intracellular signalings. We have previously shown that treatment of ovarian cancer cells, NOM1, with fibronectin (FN) stimulated matrix metalloproteinase (MMP)-9 secretion and thereby activated the invasiveness of cells via the FAK/Ras signaling pathway. By use of chemical inhibitors, we investigated the downstream effectors critical for FN-dependent secretion of MMP-9. Treatment of cells with MEK1 inhibitors, U0126 and PD98059, dramatically suppressed the secretion of MMP-9 activated by FN. Similarly, PI-3 kinase inhibitors, Wortmannin and LY294002, strongly suppressed the FN-dependent secretion of MMP-9 together with the inhibition of Akt activation. In contrast, a specific PKC inhibitor (GF109203X) showed no inhibitory effect on the FN-dependent MMP-9 secretion. Moreover, we found that both the MEK1 inhibitor and the PI3-K inhibitor, but not the PKC inhibitor, strongly suppressed the invasiveness of NOM1 cells. Taken together, our results suggest that activation of dual signaling pathways, MEK1-MAPK and PI3K-Akt, is required for the FN-dependent activation of MMP-9 secretion. Our results suggest the importance of these signaling molecules as a chemotherapeutic target for cancer. This revised version was published online in July 2006 with corrections to the Cover Date.     

CD25+ T cells induce Helicobacter pylori‐specific CD25− T‐cell anergy but are not required to maintain persistent hyporesponsiveness

The gastric pathogen Helicobacter pylori infects over half the world's population. The lifelong infection induces gastric inflammation but the host fails to generate protective immunity. To study the lack of protective H. pylori immunity, CD4⁺CD25⁺ T_reg cells were investigated for their ability to down‐regulate H. pylori‐specific CD4⁺CD25⁻ cells in a murine model. CD25⁻ lymphocytes from infected mice were hyporesponsive to antigenic stimulation in vitro even in the absence of CD25⁺ T_reg cells unless treated with high‐dose IL‐2. Transfer of CD45RB^hi naïve CD25⁻ cells from infected mice into rag1^−/− mice challenged with H. pylori resulted in severe gastritis and reduced bacterial loads, whereas transfer of CD45RB^lo memory CD25⁻ cells from H. pylori‐infected mice resulted in only mild gastritis and persistent infection. CD25⁻ cells stimulated in the absence of CD25⁺ cells in rag1^−/− mice promoted bacterial clearance, but lost this ability when subsequently transferred to WT mice harboring CD25⁺ cells. These results demonstrate that CD25⁺ cells induce anergy in CD25⁻ cells in response to H. pylori infection but are not required to maintain hyporesponsiveness. In addition, CD25⁺ cells are able to suppress previously activated CD25⁻ cells when responding to H. pylori challenge in vivo.     

胚胎干细胞源性肝干细胞在治疗性肝再生中的应用

目的： 应用治疗性肝再生模型进行胚胎干细胞(ESC)源性肝干细胞肝内移植, 观察其在肝组织替代、体内的生长分化及成瘤性等情况，为ESC移植在难治性肝病治疗中的临床应用提供实验依据。方法： 倒千里光碱+70%肝部分切除建立BALB/c小鼠的治疗性肝再生模型。用荧光示踪剂CFDA SE 标记移植细胞，将经淤胆血清“病理微环境”筛选体系筛选出的ESC源性肝干细胞经门静脉移植入治疗性肝再生模型小鼠肝内。然后荧光显微镜下观察，检测移植细胞体内分布、整合与肝细胞替代、体内生长分化等情况。2周后行白蛋白荧光免疫组化(双荧光染色)、血清白蛋白水平检测其功能状况。并通过观察其体内成瘤性对筛选出的ESC源性肝干细胞的安全性进行评估。结果： CFDA SE标记的ESC源性肝干细胞肝内移植1周，受体小鼠肝实质内可见散在绿色荧光分布。2周后，肝实质内绿色荧光分布区域明显扩大，且可见类似肝索样结构排列。共焦白蛋白荧光免疫组化(双荧光染色)结果表明，受体小鼠肝组织内可见标记细胞表达白蛋白阳性信号（呈黄色荧光），血清白蛋白水平则无明显差异（P>0.05）。6周内未见畸胎瘤形成，而将未分化的ESC移植入小鼠腋区皮下6周后则可见畸胎瘤形成。结论： 经淤胆血清“病理微环境”筛选体系筛选出的ESC源性肝干细胞移植入治疗性肝再生模型小鼠肝内后可有效整合入宿主肝板、在肝内能进一步生长分化并部分表达肝细胞功能。其安全性较好，6周内未见畸胎瘤形成。     

Interaction of transforming growth factor β1 with human glomerular epithelial cells in culture: opposite effects on synthesis of matrix proteins and on urokinase plasminogen activator

The effect of transforming growth factor- (TGF-) was analyzed on the synthesis of fibronectin, collagen type IV, and urokinase plasminogen activator in human glomerular epithelial cells in culture. An increase in the abundance of specific mRNA was found for collagen type IV and fibronectin. Fibronectin protein synthesis was also increased in TGF- treated cells; most of the de novo synthesized fibronectin was found as an unsoluble protein associated with extracellular matrix. In the same cells the amount of plasminogen activator mRNA was found leading also to a decreased surface expression of urokinase plasminogen activator. The data support the concept that by upregulating matrix protein synthesis and downregulating the plasminogen activator system, TGF- favors the development of sclerosis.Abbreviations FN Fibronectin - GEC Glomerular epithelial cells - TGF- Transforming growth factor - uPA Urokinase-type plasminogen activator     

Extracellular detection of K+ release during migration of transformed Madin-Darby canine kidney cells

 Madin Darby canine kidney cells transformed by alkaline stress (MDCK-F cells) constitutively migrate at a rate of about 1 μm·min^–1. Migration depends on the intermittent activity of a Ca²⁺-stimulated, 53-pS K⁺ channel (K_Ca channel) that is inhibitable by charybdotoxin. In the present study we examined whether this intermittent K_Ca channel activity results in a significant K⁺ loss across the plasma membrane. K⁺ efflux from MDCK-F cells should result in a transient increase of extracellular K⁺ ([K⁺]_e) in the close vicinity of a migrating cell. However, due to the rapid diffusion of K⁺ ions into the virtually infinite extracellular space, such a transient increase in [K⁺]_e was too small to be detected by conventional K⁺-selective electrodes. Therefore, we developed a ”shielded ion-sensitive microelectrode” (SIM) that limited diffusion to a small compartment, formed by a shielding pipette which surrounded the tip of the K⁺-sensitive microelectrode. The SIM improved the signal to noise ratio by a factor of at least three, thus transient increases of [K⁺]_e in the vicinity of MDCK-F cells became detectable. They occurred at a rate of 1.3 min^–1. The cell releases 40 fmol K⁺ during each burst of intermittent K_Ca channel activity, which corresponds to about 15% of the total cellular K⁺ content. Since transmembrane K⁺ loss must be accompanied by anion loss and therefore leads to a decrease of cell volume, these findings support the hypothesis that intermittent volume changes are a prerequisite for the migration of MDCK-F cells. Received: 15 April 1996 / Received after revision: 18 June 1996 / Accepted: 23 July 1996     

细胞低温显微图象的计算机处理及定量分析

本文用计算机图象处理技术对细胞显微图象进行处理和定量分析,求出了细胞面积在低温保存中极其重要的参数。实验证明,计算机测量比人工精度高,误差小,同时新颖的标号去噪方法也非常有效。     

Autoantibodies to human melanocyte-specific protein Pmel17 in the sera of vitiligo patients: a sensitive and quantitative radioimmunoassay (RIA)

Lethally irradiated LEW rats reconstituted with syngeneic bone marrow and given CsA for a 4-week period develop a graft-versus-host-like disease upon withdrawal of CsA. This T cell-mediated autoimmune disease is referred to as CsA-induced autoimmunity (CsA-AI). CsA-AI-susceptible LEW rats and resistant BN rats differ greatly in the composition of their peripheral T cell compartment. To dissect the role of MHC and non-MHC genes in the development of peripheral T cell subsets in combination with susceptibility to CsA-AI the respective MHC congenic strains (LEW-1N and BN-1L) were examined for their T cell subsets and for their ability to develop CsA-AI. In this study we show that the Th1/Th2-like cell ratio as well as susceptibility to CsA-AI are under control of the non-MHC genes. This suggests that the Th1/Th2-like cell ratio is a critical determinant for development of CsA-AI. Alternatively, resistance can be attributed to lack of target organ susceptibility due to the absence of the target autoantigen in resistant rat strains. This interpretation is rejected, since both BN as well as BN-1L rats consistently develop the characteristic macroscopic and microscopic signs of CsA-AI upon adoptive transfer with autoreactive LEW-1N and LEW T cells, respectively. Therefore, it can be concluded that the non-MHC genes encode for immune deviation and thereby determine susceptibility or resistance to CsA-AI.     

大鼠胎儿表皮干细胞的分离鉴定和体内分化

目的探索一种简单而又高效的分离大鼠胎儿表皮干细胞方法,以及观察其在体内环境中的分化潜能。方法采集ED14、ED16、ED18及ED20不同发育阶段的SD大鼠胎儿皮肤,HE染色观察其结构。鼠尾胶原快速黏附法筛选胎鼠表皮细胞,在无血清培养基(K-SFM)中进行培养。免疫组织化学方法检测CK-19和1β-整合素表达情况。同时,也对细胞周期和细胞增殖能力进行检验。经荧光染料(PKH26)标记过的胎鼠表皮干细胞与多孔凝胶海绵结合,然后植入大鼠肾被膜下进行诱导分化。结果在ED18之前皮肤表皮和真皮尚未充分完成分化。使用快速黏附法能够有效的从ED18胎鼠皮肤分离到表皮干细胞。获得的细胞CK19和1β整合素呈阳性表达,细胞周期分析显示,细胞呈慢周期性,移植体在肾被膜下分化并展现典型的表皮样结构。结论表皮干细胞存在于早期发育皮肤中,但在ED18才能使用快速黏附法分离到表皮干细胞。此时的胎鼠表皮干细胞具有向表皮分化的能力。