大鼠牙髓细胞的分离培养及超微结构观察

目的 探讨牙髓细胞的培养方法和生长状况,观察其形态结构特征,为进一步研究牙齿的发育提供实验基础.方法 采用胶原酶消化分离的方法分离大鼠的牙髓细胞并在DMEM培养液中培养,运用透射和扫描电镜技术观察细胞的形态结构特征.结果 培养的牙髓细胞呈梭形,细胞生长状况良好,细胞器发育正常,并且有细胞增殖和分裂能力.结论 利用酶消化分离的方法分离培养的牙髓细胞,能够保持其生活状态及增殖分裂能力.     

肺癌靶向多肽荧光分子探针的研制及其应用

目的:选择能与整合素α3受体结合的小分子多肽cNGQGEQc-L作为靶向载体，将羧基荧光素（FAM）与cNGQGEQc-L连接构建荧光分子探针，通过荧光成像探讨荧光多肽分子探针用于肺腺癌显像的可行性。方法:利用倒置荧光显微镜观察FAM-cNGQGEQc-L与肺腺癌A549细胞结合部位，流式细胞仪检测荧光多肽与A549细胞的竞争抑制实验，观察FAM-cNGQGEQc-L随浓度的增加与肺腺癌A549细胞结合能力的变化情况。通过小动物活体成像仪，观察荧光多肽在荷瘤裸鼠体内的生物分布特点。结果:倒置荧光显微镜显示荧光多肽cNGQGEQc-L能与A549细胞结合，结合部位在细胞膜和细胞质中。流式细胞仪测试结果证明荧光多肽与A549细胞的结合具有特异性和饱和性，当FAM-cNGQGEQc-L浓度为0.125 mmol/L时，荧光多肽与A549细胞的结合趋近饱和。荷瘤裸鼠活体成像显示移植瘤能够摄取荧光多肽，且荧光多肽通过泌尿系统和胆道系统排泄。结论:体外、体内荧光实验结果显示，荧光多肽分子探针FAM-cNGQGEQc-L可与肺腺癌A549细胞、肺癌移植瘤结合，能够特异性靶向肺腺癌。     

Integrin α6 expression in human prostate carcinoma cells is associated with a migratory and invasive phenotypein vitro andin vivo

Cell adhesion and migration are important features in tumor invasion, being mediated in part by integrins (extracellular matrix receptors). Integrins are significantly decreased in human prostate cancer. An exception is 6 integrin (laminin receptor) which persists during prostate tumor progression. We have selected high (DU-H) and low (DU-L) expressors of 6 integrin from a human prostate tumor cell line, DU145, to assess experimentally the importance of 6 integrin in tumor invasion. DU-H cells exhibited a four-fold increased expression of 6 integrin on the surface compared to DU-L cells. Both cell types contained similar amounts of 3 and 5 integrin. The DU-H cells contained 6 subunits complexed with both the 1 and 4 subunits whereas DU-L cells contained 6 complexed only with 4. DU-H cells were three times more mobile on laminin as compared to DU-L, but adhered similarly on laminin. Adhesion and migration were inhibited with anti-6 antibody. Each subline was injected intraperitoneally into SCID mice to test its invasive potential. Results showed greater invasion of DU-H compared to DU-L cells, with increased expression of a6 integrin on the tumor at the areas of invasion. These data suggest that 6 integrin expression is advantageous for prostate tumor cell invasion.     

妊娠17～37周胎儿可溶性白介素2受体和NK细胞含量的变化

目的：探讨妊娠17～37周正常和宫内感染时胎儿外周血可溶性白介素2受体（Soluble interleuldn-2 receptor，sIL-2R）和自然杀伤细胞（Natural killer，NK）含量的变化。方法：超声引导下行脐带穿刺术，收集129例胎儿外周血，包括97例正常对照组胎儿血，32例宫内感染组（单纯疱疹病毒感染、弓形虫感染、风疹病毒感染）胎儿血，采用双色免疫荧光标记流式细胞仪技术测定胎JLPF周血NK细胞百分率，双抗体夹心酶联免疫吸附试验测定胎JLPF周血中sIL-2R的含量，分析生理状态下胎儿外周血NK细胞、sIL-2R的状况和宫内感染时NK细胞和sIL-2R含量的变化。结果：妊娠17—37周胎儿外周血NK细胞、sIL-2R含量不随孕周改变，r（NK）=-0．03，P〉0．05；r（sIL-2R）=0．167，P〉0．05，宫内感染时NK细胞含量减少，sIL-2R含量增多，与正常对照组相比差异有显著意义；t（NK）=4．29，P〈0．01；t（sIL-2R）=-5．833，P〈0．01。结论：妊娠17—37周胎儿外周血有一定量的NK细胞和sIL-2R存在，但机体免疫功能仍不完善，宫内感染时机体容易出现免疫抑制状态。     

Use of class II tetramers for identification of CD4+ T cells

Multivalent MHC class II molecules containing peptide antigens are useful tools for the detection of antigen specific human CD4+ T cells. Tetramers produced by exogenous peptide loading onto empty class II molecules are comparable to tetramers with peptide tethered to the class II chain covalently, but have many practical advantages. Conditions for optimal peptide loading to generate tetramers are discussed and optimal conditions of using tetramers for staining T cells are examined. As the frequency of antigen specific CD4+ T cells in peripheral blood is low, we demonstrate that an in vitro expansion step is effective in detecting low frequency T cells. Two new applications with tetramers, their uses for mapping T cell epitopes and for the detection of low affinity T cells are described. In a clinical setting, potential applications include using these reagents for monitoring disease progression during clinical intervention.     

Anti-T-cell strategies in the treatment of allergic disease

Specific allergen immunotherapy (SIT) has been shown to be effective in modulating allergic responses in diseases such as rhinitis and asthma. However, the ability of whole allergen to cross link mast cell bound IgE, resulting in release of mediators such as histamine, has limited the application of this therapy to carefully selected patients who have failed conventional pharmacotherapy. The use of peptide sequences corresponding to T cell epitopes of the allergen has been postulated as an alternative to SIT in which high molar doses of T cell epitope can be delivered over a shorter time period and with improved safety. Using peptides from the sequence of the major cat allergen, Fel d 1, we have demonstrated the ability to induce transient T cell activation, resulting in isolated late asthmatic reactions, which are followed by prolonged periods of allergen-specific hyporesponsiveness, both to peptide re-challenge and to cutaneous challenge with whole allergen. Thus, peptide therapy may prove safe and efficacious in the treatment of allergic diseases.     

Properties and regulation of chloride channels in cystic fibrosis and normal airway cells

The present study examines the properties of Cl^–channels in cultured respiratory cells of cystic fibrosis (CF) patients and normal (N) individuals. In excised membrane patches the conductances for CF and N Cl^– channels were larger at positive as compared to negative clamp voltages (V _c): 74±2.6 (V _c > 0) and 47±2.0 pS (V _c < 0) for CF (n= 57) and 69±3.6 (V _c > 0) and 45±2.3 pS (V _c < 0) for N (n=35). The open probability (P _o) of the channel increased markedly with depolarization. Both the voltage dependence of the conductance and of P _o contribute to the outward rectification of the channel. The time histogram analysis reveals two open and two closed time constants. The selectivity of the channel was Cl^–=Br^– =I^– > NO ₃ ^– gluconate. The channel was inhibited reversibly by 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) at 10^–7 mol/l to 10^–5 mol/l. While Cl^– channels were present in cell attached patches of N cells, they were absent in those of CF cells. The mean conductance for cell attached (N) Cl^– channels was 76±3.2 pS for positive clamp voltages (V _c) and 46±3.9 pS for negative V _c (n=8). When the membrane patches were excised from CF cells Cl^– currents appeared spontaneously (n=19). The immediate appearance (within 1 s) of Cl^– channels after excision was observed at positive (n=6) as well as at negative clamp voltage (n=13). Excision activation of CF Cl^– channels was observed at low (< 10^–9 mol/l) or high (10^–3 mol/l) calcium activities on the cytosolic side of the excised patch. Variation of the Ca⁺ activity (< 10^–9–10^–3 mol/l) or pH (6.5–8.5) on the cytosolic side exerted no effects on these Cl^– channels. These results suggest that Cl^– channels are present in the apical membrane of CF and N respiratory cells but they seem to be inhibited in intact CF cells. Excision of the patch and hence removal of the cytosolic inhibitor leads to an activation of Cl^– channels. The Cl^– channels in excised patches of N and CF cells have identical properties.     

Transfection of Lepidopteran insect cells with Baculovirus DNA

Summary Several protocols are presented for preparation and transfection of Baculovirus and plasmid DNAs into Lepidopteran insect cells using the calcium-phosphate co-precipitation technique. Important parameters for optimum efficiency include the inherent susceptibility of the recipient cell line for transfection, and the method of preparation of viral and plasmid DNAs. The protocols presented provide reproducible high efficiencies for transfection of several Lepidopteran cell lines.     

P-selectin glycoprotein ligand-1 mediates rolling of mouse bone marrow-derived mast cells on P-selectin but not efficiently on E-selectin

It has been shown recently that mast cells play an essential role as a source of tumor necrosis factor-α production during neutrophil recruitment to sites of bacterial infection. Increased numbers of mast cells are indeed noted at sites of wound healing and inflammation. These cells are either recruited from the bone marrow or proliferate locally under cytokine stimulation. Little is known about how mast cell progenitors extravasate into tissue. Using antibody-like fusion proteins of mouse E-selectin and P-selectin, we have analyzed the ability of immature mouse bone marrow-derived mast cells (BMMC) to interact with the endothelial selectins. The P-selectin glycoprotein ligand-1 (PSGL-1) was affinity-isolated from detergent extracts of surface biotinylated BMMC with both selectin-IgG fusion proteins. However, only P-selectin-IgG, but not E-selectin-IgG showed significant interaction with intact BMMC as tested by flow cytometry and cell attachment assays with the immobilized fusion proteins under flow and non-flow conditions at physiological shear stress. Thus, in spite of carrying the necessary carbohydrate modifications which enable solubilized PSGL-1 to bind avidly to E-selectin, PSGL-1 on the surface of BMMC is presented in a way that prevents it from interacting efficiently with E-selectin. Affinity-purified rabbit antibodies against mouse PSGL-1 almost completely blocked the interaction of BMMC with P-selectin-IgG in flow cytometry as well as in cell adhesion assays under static and under flow conditions. Our data reveal that PSGL-1 is the major binding site for P-selectin on mouse BMMC progenitors, but does not support efficient interactions with E-selectin.