L-精氨酸对任意型移植皮瓣组织中基质金属蛋白酶2和基质金属蛋白酶2抑制因子表达的影响

目的：观察L-精氨酸对任意型移植皮瓣组织中基质金属蛋白酶2、基质金属蛋白酶2抑制因子表达的影响，分析L-精氨酸对移植皮瓣保护作用的途径。方法：于2005—06／09在武汉大学人民医院动物实验室完成取材、组织学和组织化学实验；2005—10／2006—02在武汉大学医学院人体解剖与组织胚胎实验室完成图像分析、照相和统计学处理。①实验材料和分组：取Wistar大白鼠79只，按随机数字表法分为3组：正常对照组（n=5），仅接受生理盐水处理，不形成皮瓣，只切开皮肤；皮瓣模型组（n=37），形成皮瓣，接受生理盐水处理；L-精氨酸干预组（n=37），形成皮瓣，接受L-精氨酸处理。②实验评估：肉眼观察皮瓣成活情况，利用HPIAS-2000多媒体彩色病理图像分析系统求出皮瓣平均成活面积率。应用光镜观察皮瓣组织学变化；用免疫组织化学SP法检测基质金属蛋白酶2、基质金属蛋白酶2抑制因子抗原。比较各组免疫组织化学反应阳性颗粒的平均吸光度、阳性面积率并作统计学分析。结果：纳入85只大鼠，79只大鼠进入结果分析，皮瓣模型组和L-精氨酸干预组各有3只大鼠死亡。①术后7d，L-精氨酸干预组皮瓣成活面积率显著高于皮瓣模型组（P〈0．01）。②术后24h，72h皮瓣模型组皮瓣组织中基质金属蛋白酶2和基质金属蛋白酶2抑制因子呈强阳性表达，L-精氨酸干预组呈弱阳性或阴性，正常对照组呈阴性。③皮瓣模型组皮瓣组织中基质金属蛋白酶2和基质金属蛋白酶2抑制因子的平均吸光度及阳性面积率均显著高于L-精氨酸干预组和正常对照组（P〈0．01）。结论：外源性L-精氨酸可能通过抑制任意型移植皮瓣组织中基质金属蛋白酶2、基质金属蛋白酶2抑制因子的过度表达，提高任意型皮瓣的成活率。     

Susceptibility of leishmania to oxygen intermediates and killing by normal macrophages

This study demonstrates that the promastigote form of virulent Leishmania donovani and Leishmania tropica are both deficient in endogenous enzymatic scavengers of H(2)0(2) (catalase, glutathione peroxidase) and susceptible to low fluxes of H(2)O(2) in a cell-free model. In addition, the killing of promastigotes by H(2)0(2) is markedly enhanced in the presence of a peroxidase and halide. Promastigotes also readily trigger the macrophage oxidative burst including the generation of H(2)0(2), and most intracellular promastigotes are killed within 18 h by unstimulated normal resident cells. Catalase, but not scavengers or quenchers of O(2)(-), OHx, or (1)O(2), protected promastigotes in a cell-free xanthine oxidase microbicidal system, and catalase also partially inhibited the leishmanicidal activity of resident macrophages. Thus, amongst various oxygen intermediates, H(2)0(2) alone appeared to be both necessary and sufficient for promastigote killing. Depriving macrophages of exogenous glucose, which inhibits the generation of oxygen intermediates, achieved effects similar to catalase treatment. These observations directly contrast with the intracellular parasite, T. gondii which is richly endowed with catalase and glutathione peroxidase, highly resistant to H(2)0(2), and requires products of O(2)(-)-H(2)0(2) interaction for effective oxidative killing. Toxoplasmas also fail to trigger the respiratory burst of normal macrophages, and readily multiply within these cells (1-5). Macrophages first activated by in vivo or in vitro immunologic stimuli, however, display an enhanced capacity to generate oxygen intermediates beyond O(2)(-) and H(2)0(2), and are able to kill toxoplasmas or inhibit their intracellular replication (1, 2). These studies illustrate the wide spectrum of susceptibility to oxidative products which appears to exist for virulent intracellular protozoans, and indicate that such differences may be reflected in contrasting fates of parasites within cell-free oxidative environments and the cytoplasm of normal resident macrophages. In addition, these observations also demonstrate that nonactivated phagocytes may display effective microbicidal activity against certain intracellular pathogens utilizing an oxygen-dependent mechanism.     

Comparison of FDG-PET and dynamic contrast-enhanced MRI in the evaluation of suggestive breast lesions

The aim of our study was a direct comparison of the ability of positron-emission tomography with FDG-PET and of magnetic resonance imaging (MRI) to determine whether breast lesions were benign or malignant and of the two imaging methods capability of depicting eventual multifocal disease. We performed both PET and MRI in 36 patients (40 lesions) who were scheduled for surgery because of suggestive mammographic, sonographic and/or clinical findings. A final histological classification was available for all lesions. Tumour size ranged from 5 to 45 mm (mean 16.7 mm). Sensitivity for lesions, sensitivity for patients, specificity for lesions and specificity for patients were 68.0%, 76.2%, 73.3%, and 73.3% for PET and 92.0%, 95.2%, 73.3%, and 73.3% for MRI, respectively. MRI was more sensitive than FDG-PET in disclosing malignant breast tumours and was also more accurate than FDG-PET in the assessment of multifocal disease. The lower sensitivity of FDG-PET than of MRI seems to be due to difficulties in reliable imaging of carcinomas smaller than 10 mm and of lobular carcinomas.     

Respiratory syncytial virus infection enhances the response to laryngeal chemostimulation and inhibits arousal from sleep in young lambs*

To evaluate the effect of respiratory syncytial virus (RSV) infection on the response to laryngeal chemostimulation (LCS) with water, five lambs were inoculated with human RSV and three lambs were given control media at an age of 3-5 days. During RSV infection, LCS resulted in increased inhibition of minute ventilation and delayed recovery of regular breathing. Sleep further increased the response, and arousal was less likely to occur in active sleep. Two of the five infected lambs needed resuscitation after LCS when arousal was absent. Histological studies showed bronchiolitis and pneumonitis. Laryngeal tastebud morphology was unchanged at 8 days after inoculation. However, infected lambs had disrupted tastebuds 4-6 weeks after infection. Failure to arouse and to terminate reflex apnea may play a role in the pathogenesis of the sudden infant death syndrome associated with respiratory tract infection.     

Screening tests for blood donors presumed to have transmitted the acquired immunodeficiency syndrome

We investigated 18 sets of blood donors from 12 to 50 months after they donated blood to recipients who subsequently developed the acquired immunodeficiency syndrome (AIDS). Within each donor set, only one donor was suspected of having transmitted the disease (ie, member of an AIDS risk group). The other donors (n = 189) were not risk group members and served as controls. A number of laboratory tests distinguished suspected from nonsuspected donors, including determination of T helper/T suppressor cell ratio, antibody to hepatitis B core antigen, and immune complexes, but none of these was as sensitive and specific as tests for antibody to the human retrovirus, HTLV-III/LAV.     

Characterization of nonlymphoid cells derived from rat peripheral lymph

Mesenteric lymphadenectomy in rats is followed by union of peripheral and central lymphatics, allowing the collection of intestine-derived peripheral lymph cells via the thoracic duct for several days. These cells include a proportion of nonlymphoid cells (NLC) that show irregular and heterogeneous surface morphology including long pseudopodia and veils. They stain variably for nonspecific esterase and acid phosphatase and are ATPase-positive. Their nuclei are irregular and some contain cytoplasmic inclusions, some of which show peroxidase activity and/or contain DNA. NLC have a range of densitites generally lower than that of lymphocytes. Freshly collected NLC express the leukocyte-common antigen (defined by monoclonal antibody MRC Ox 1) and Ia antigens (I-A and I-E subregion products defined by monoclonal antibodies) but they show a relative lack of other surface markers normally found on rat B or T lymphocytes (W3/13, W3/25, MRC Ox 12 (sIg), MRC Ox 19) or rat macrophages (FcR, C’R, mannose R, W3/25). In general NLC are only weakly adherent to glass or plastic. Although a subpopulation of NLC appear to have had a phagocytic past, freshly collected NLC fail to phagocytose a variety of test particles in vitro. NLC also appear incapable of pinocytosis in vitro. This heterogeneity may represent distinct subpopulations of NLC or different stages in the development of a single cell lineage. Direct cannulation of mesenteric lacteals shows that the majority of NLC are derived from the small intestine and their precursors appear to be present both in lamina propria and Peyer's patches. Kinetic studies, following irradiation or intravenous tritiated thymidine, show that the majority of NLC turn over rapidly in the intestine with a modal time of 3-5 d. Studies with bone marrow chimeras show that they are derived from a rapidly dividing precursor present in normal bone marrow. NLC occur at very low frequencies in normal thoracic duct lymph at all times following cannulation. The evidence presented suggests that NLC closely resemble mouse lymphoid dendritic cells. This conclusion is supported by evidence already obtained showing that NLC are potent stimulators of the semi-allogeneic rat primary mixed leukocyte reaction. In addition to the ceils resembling dendritic cells rare monocytoid cells are found in thoracic duct lymph of lymphadenectomized specific pathogen-free rats. The proportion of these cells increases greatly when the animals are conventionally housed. It seems probable that the physiological function of NLC is to act as accessory cells in the lymph nodes to which they normally drain. Methods for enriching NLC and thus facilitating analysis of their functions are discussed.