镁对在体兔缺血—再灌心脏的电生理效应

本实验通过结扎兔冠状动脉左室支复制动脉缺血－再灌注模型，应用心外膜接触电极记录单相动作电位，观察后除极电位在再灌注性心律失常中及镁离子的拮抗作用。结果表明，再灌性心律失常的５２．６％与早期后去极化有关。硫酸镁可终止及预防ＲＡ，对再灌中出现触发活动有抑制作用。     

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（     

Effect of melanin produced by a recombinant Escherichia coli on antibacterial activity of antibiotics.

A recombinant plasmid, pYL-1, containing a tyrosinase gene whose expression is under the control of a phage T5 promoter and 2 lac operators, was constructed. Escherichia coli JM109 harboring pYL-1 was used for production of bacterial melanin. A simple procedure for the isolation and purification of melanin was developed. The ultraviolet (UV)-visible light absorption spectra of melanin prepared by chemical synthesis and derived from different organisms, including bacteria, a plant and an animal source, were determined. Melanins produced by both bacteria and chemical synthesis showed a steady increase of absorption at wavelengths of UV light ranging from approximately 200-400 nm, while melanin derived either from plant or animal sources showed an additional discrete absorption peak at wavelength 280 nm upon a similar steady increase of absorption. This additional absorption peak could be due to the presence of protein-bound melanins in animal and plant sources while a free form of melanin was obtained from bacteria and chemical synthesis. Analysis of the effect of bacterial melanin on the activity of antibiotics against E. coli revealed that the activities of polymyxin B, kanamycin, tetracycline, and ampicillin were markedly reduced in the presence of melanin, whereas the activity of norfloxacin was not affected. The reduction of the antibacterial activity may result directly from the interaction of antibiotics with melanin. However, the mechanism of this interaction remains to be demonstrated.     

Prominent proliferative response of peripheral blood mononuclear cells to a recombinant non-structural (NS3) protein of hepatitis C virus in patients with chronic hepatitis C.

The proliferative response of peripheral blood mononuclear cells (PBMC) to a recombinant non-structural (NS3) protein of hepatitis C virus (HCV) was studied in 41 patients with chronic hepatitis C. Of them, 28 had chronic persistent hepatitis (CPH) and 13 chronic active hepatitis (CAH). The positive proliferation rate of PBMC to the recombinant NS3 protein, T9Ag, was 66% in the 41 patients (77% in CAH versus 61% in CPH; P > 0.05) when stimulation index (SI) = 4 was set as the cut-off value. However, mean SI of CAH patients was significantly higher than that of CPH patients (8.3 +/- 5.2 versus 5.1 +/- 3.6; P < 0.05). Six other chronic hepatitis patients who were repeatedly negative for anti-HCV antibody but positive for serum HCV RNA also had an SI of > or = 4.0. The frequency of cellular immune response to the T9Ag is among the highest results obtained by using HCV antigens tested so far. Our studies thus indicate that NS3 is an immunologically important region of HCV for T cells. Moreover, the proliferative response to T9Ag may help to establish hepatitis C etiology in chronic hepatitis patients who are seronegative with currently available anti-HCV assays.     

Thymoma and hypogammaglobulinemia (Good's syndrome): a case report.

Good's syndrome is extremely rare and refers to an acquired B and T cell immunodeficiency in thymoma patients. We report a 51-year-old female thymoma patient who presented with recurrent herpes zoster, pneumonia, diarrhea and opportunistic infections. She was found to have acquired hypogammaglobulinemia with absent B cells. Despite repeat intravenous immunoglobulin replacement and antibiotic therapy, she died of bacterial pneumonia-induced acute respiratory distress syndrome. Clinicians should look for evidence of immunologic dysfunction in thymoma patients presenting with recurrent infections.     

A tctex1-Ca2+ channel complex for selective surface expression of Ca2+ channels in neurons

Voltage-gated Ca(2+) channels (VGCCs) are important in regulating a variety of cellular functions in neurons. It remains poorly understood how VGCCs with different functions are sorted within neurons. Here we show that the t-complex testis-expressed 1 (tctex1) protein, a light-chain subunit of the dynein motor complex, interacts directly and selectively with N- and P/Q-type Ca(2+) channels, but not L-type Ca(2+) channels. The interaction is insensitive to Ca(2+). Overexpression in hippocampal neurons of a channel fragment containing the binding domain for tctex1 significantly decreases the surface expression of endogenous N- and P/Q-type Ca(2+) channels but not L-type Ca(2+) channels, as determined by immunostaining. Furthermore, disruption of the tctex1-Ca(2+) channel interaction significantly reduces the Ca(2+) current density in hippocampal neurons. These results underscore the importance of the specific tctex1-channel interaction in determining sorting and trafficking of neuronal Ca(2+) channels with different functionalities.     

卡介苗多糖核酸对过敏性支气管哮喘外周血单个核细胞TH1/TH2反应的作用

目的观察卡介苗多糖核酸(BCG-PSN)对支气管哮喘患者外周血淋巴细胞TH1/TH2反应的作用,并与结核菌素纯蛋白衍生物(TB-PPD)进行比较. 方法缓解期过敏性支气管哮喘患者16例,对照组健康成人13例,分离外周血单个核细胞(PBMC),分别加入不同浓度的BCG-PSN(1、10、100、1000 μg/ml)、TB-PPD(10 μg/ml)、尘螨抗原(DerP, 10 μg/ml)体外培养4 d,不加刺激剂者为阴性对照.收集培养上清,ELISA检测IFN-γ、IL-5浓度的变化. 结果 PSN(1～100 μg/ml)刺激正常人PBMC分泌IFN-γ水平均高于哮喘患者(P＜0.05).BCG-PSN(10 μg/ml)可以刺激哮喘患者PBMC分泌IFN-γ(358.7 pg/ml,范围0～2433.0 pg/ml),但显著低于同等浓度的TB-PPD刺激作用(13 036 pg/ml,范围600.5～35 100.0 pg/ml,P＜0.01).PSN刺激PBMC分泌IFN-γ呈浓度依赖性,当浓度达到100 μg/ml时,与低浓度相比刺激作用显著增强(P＜0.01),与TB-PPD的刺激作用类似.DerP刺激哮喘患者PBMC分泌IL-5水平显著高于正常人(P＜0.05).BCG-PSN刺激PBMC分泌IL-5的作用较弱,显著低于TB-PPD和DerP的刺激作用. 结论 BCG-PSN具有一定的TH1刺激作用,但低于TB-PPD的刺激作用,有待对BCG-PSN组分进一步优化以增强疗效.     

Epstein-Barr virus-associated smooth muscle tumor in patients with acquired immunodeficiency syndrome.

Epstein-Barr virus (EBV)-associated smooth muscle tumor (SMT) is a recognized but uncommon disease that is found to occur in patients with immunocompromised conditions such as acquired immunodeficiency syndrome (AIDS). These tumors may be multifocal and located at unusual sites, such as the brain and liver. This report describes the case of 2 AIDS patients with EBV-associated SMT and highlights the features and outcome of this rare but potentially important tumor in human immunodeficiency virus management.