Effects of N-acetylcysteine on bacterial clearance

Abstract. The aim of this study was to investigate whether the oxygen radical scavenger N -acetylcysteine ( N -AC) impairs bacterial clearance, thus predisposing the host to increased risk of disease. Blood clearance of Escherichia coli and organ colonization were investigated in anaesthetized rabbits after pretreatment with N -AC (250 mg kg^-1 body weight, n = 16) and in sham-operated animals ( n = 12). To enable quantification of the clearance process, defined numbers of exogenous E. coli [1.3 times 108 colony-forming units (CFUs)] were injected intravenously. Parameters monitored were kinetics of bacterial elimination from the blood, and polymorphonuclear leucocyte (PMN) oxidative burst activity. Samples of liver, kidney, spleen and lung were collected for bacterial counts. Compared with controls, pretreatment with N -AC resulted in delayed bacterial elimination from blood and higher organ colonization with increased numbers of E. coli in liver, lung and kidney ( P < 0.05). N -AC treatment was associated with a suppressed PMN oxidative burst activity. Impaired bacterial clearance and enhanced organ colonization in N -AC-treated animals correlated with reduced oxidative burst activity, suggesting impaired granulocyte-dependent bacterial killing due to N -AC application.     

大气颗粒物健康效应生物学机制研究进展

大量流行病学研究发现，大气颗粒物的污染水平与心肺系统疾病的超额发病、死亡存在密切关联，但其毒理学机制尚未阐明。本文对近年来大气颗粒物毒理学研究进行综述，包括大气颗粒物对呼吸系统、心血管系统及神经系统的毒性作用，并对氧化应激损伤、细胞钙稳态失衡及激活关键转录因子等分子毒理学机制进行了初步的阐述。     

慢性乙型肝炎病人血清中游离白细胞介素2受体升高的意义

应用放射免疫分析法测定慢性活动性肝炎(CAH)和慢性迁延性肝炎(CPH)病人及健康人血清中游离白细胞介素2受体(fIL2R)水平,CAH和CPH病人的cpm分别是2326±617及1277±397,健康人仅为343±213。结果发现:CAH和CPH病人血清中fIL2R水平均显著高于健康人(P<0.01);CAH病人血清中fIL2R水平高于CPH病人(P<0.01)。提示,慢性乙型肝炎病人血清中fIL2R水平升高可能与其免疫应答异常及炎症活动性有关。     

牛磺酸对应激大鼠心肌损伤的保护机制

以异丙肾上腺素诱导的大鼠应激为模型，研究牛磺酸对心肌及血清中自由基系统与游离脂肪酸含量组成的影响。与对照组比较，结果Ｉｓｏ组心肌中ＦＲ、ＬＰＯ、ＣＫ、ＬＤＨ、Ｃ１６：０、Ｃ１８：０、Ｃ１８：１、ＦＦＡ与Ｃ１８：０／ＦＦＡ值显著升高，ＳＯＤ、Ｃ１８：３、Ｃ２０：４ＰＵＦＡ／ＦＦＡ值显著降低；血清中ＬＰＯ、ＣＫ、Ｃ１６：０、Ｃ１８：１、ＦＦＡ值显著升高，Ｃ１８：３、Ｃ２０：４、ＰＵＦＡ／ＦＦＡ及ＳＯＤ值呈下降趋势，牛磺酸对纠正应激引起的上述变化有显著作用，结果提示牛磺酸可通过减少自由基产生，增加抗氧化酶活性来减少脂质过氧化反应，维持细胞膜完整，影响心肌中ＦＦＡ含量及组成，保护心肌免受应激损伤。     

加热及增加细胞内氧自由基水平对恶性胶质瘤细胞生物学特性的影响

本文就加热及同时增加细胞内氧自由基水平对恶性胶质瘤细胞存活、增殖和细胞间隙连结通讯的影响做初步观察。用Ｍ．Ｔ．Ｔ法测定胶质瘤细胞存活率；用Ｋｉ－６７抗增殖细胞核抗原单克隆抗体，通过免疫组织化学ＡＢＣ染色分析胶质瘤细胞的增殖活性；用划痕染料示踪技术观察胶质瘤细胞的细胞间隙连结通讯。结果表明，Ｈ２Ｏ２和３ＡＴ能增强加热对胶质瘤细胞存活与增殖的抑制作用，促进胶质瘤细胞间隙连结通讯的改善，存在着明显的剂量和时间效应。实验结果提示，通过内外源性增加胶质瘤细胞内的氧自由基水平，将有助于强化加热治疗胶质瘤效果，并可以减少加热的剂且，降低副作用。     

卡托普利对.OH所致异常血流动力学的保护作用

．ＯＨ生成液０．０５ｍｌ．１００ｇ＾－１经胶静脉注入心脏，可使麻醉大鼠的左心室收缩压力、左心室压力与心率乘积、左心室压力上升最大速率和左心室压力下降最大速率明显下降。     

Surgical results of performing R4 gastrectomy for gastric cancer located in the upper third of the stomach

Because gastric cancers located in the upper third of the stomach are difficult to detect at an early stage, the surgical results remain poor. We performed R4 gastrectomy as a radical procedure for 25 patients, involving complete resection of the latero-aortic and interaorticovenous lymph modes above and below the left renal vein, in combination with the ordinary R2 or R3 gastrectomy (the R4 group). These patients were compared with 156 others who underwent R2 gastrectomy alone (the R2 group). There were no significant differences in operation time, blood loss, or the incidence of complications between the two groups; however, when the survival rates of the patients with tumors invading beyond the subserosa were compared, the 5-year survival rate was found to be significantly higher in the R4 group than in the R2 group. Furthermore, in patients with para-aortic nodal involvement, a significant survival advantage was observed in the R4 group, as compared with the R2 group. These results suggest that the R4 gastrectomy is a rational approach for patients with advanced gastric cancer located in the upper third of the stomach.     

Study on lymphocyte activation and proliferation induced by anti-CD3 McAb

Summary T cell activation and proliferation via CD₃-TCR complex were investigated by lymphocyte DNA synthesis in vitro. Several interfering factors were also discussed. The result indicated that lymphocyte activation and proliferation are calciumdependent. A rise of cytoplasmic free Ca²⁺ quickly following activation with CD₃ McAb is mainly due to intracellular mobilization of Ca²⁺, while lymphocyte proliferation needs both intracellular mobilization of Ca²⁺ as well as influx of extracellular Ca²⁺. It was confirmed that CTX sensitive G protein plays a role in regulating T cell proliferation by pretreatment with CTX suppressing lymphocyte³H-TdR incorporation obviously. PLC and PKC inhibitor neomycin and P. S. S could also decrease T cell proliferation.     

Metabolic myocardial viability assessment with iodine 123-16-iodo-3-methylhexadecanoic acid in recent myocardial infarction: Comparison with thallium-201 and fluorine-18 fluorodeoxyglucose

The best test presently available to ascertain residual viability within an infarct-related area involves the use of fluorine-18 fluorodeoxyglucose (FDG) to detect the persistence of some cellular metabolism. Rest reinjection of thallium-201 is a less accurate alternative but is easy to perform. Iodinated fatty acids, which are used with standard gamma cameras, are proposed as markers of cellular metabolism. This study was performed to assess the value of 16-iodo-3-methyl-hexadecanoic acid (MIHA) as a marker of the residual cellular metabolism by comparison with FDG in patients with a recent myocardial infarction, and to evaluate its contribution compared with the²⁰¹Tl stress-redistribution-reinjection technique. Stress-redistribution-reinjection²⁰¹T1 imaging, rest MIHA imaging and glucoseloaded FDG imaging were performed in 22 patients with recent myocardial infarction. Out of the 628 myocardial segments obtained from the left ventricular analysis, 400 were hypoperfused (relative uptake <0.75 of maximum uptake on stress²⁰¹T1 imaging), 177 of which were severely hypoperfused (relative uptake <0.50). Receiver operating characteristic (ROC) curves for predicting metabolic myocardial viability with FDG were derived from the results in respect of (a)²⁰¹T1 activity during exercise, redistribution and reinjection and (b) MIHA up-take, using the two FDG thresholds most commonly considered to define metabolic viability (0.50 and 0.60). Analysis of the 400 hypoperfused segments demonstrated that²⁰¹T1 reinjection was the most accurate test in predicting the presence of myocardial viability (area under the ROI curves=0.85 and 0.86 at the 0.50 and 0.60 FDG thresholds, respectively;P<0.05 vs other tests). The global predictive values of MIHA and²⁰¹T1 reinjection were, respectively, 0.87 and 0.89 at the 0.50 FDG threshold (NS), and 0.82 and 0.87 at the 0.60 FDG threshold (NS). When only the 177 severely hypoperfused segments were considered,²⁰¹T1 reinjection remained the most accurate test (accuracy 0.84 at the 0.50 FDG threshold and 0.82 at the 0.60 FDG threshold), while the accuracy of MIHA decreased significantly (0.78 at the 0.50 FDG threshold and 0.73 at the 0.60 FDG threshold,P<0.05 vs²⁰¹T1 reinjection). In all circumstances, MIHA was less specific than²⁰¹T1 reinjection for the detection of metabolic viability. In conclusion, in patients with recent myocardial infarction, MIHA accurately detects the persistence of metabolic viability, but is not superior to²⁰¹T1.