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91.
Oxygen-derived free radicals and hemolysis during open heart surgery   总被引:2,自引:0,他引:2  
Reperfusion injury occurs during open-heart surgery after prolonged cardioplegic arrest. Cardiopulmonary bypass also is known to cause hemolysis. Since reperfusion of ischemic myocardium is associated with the generation of oxygen free radicals, and since free radicals can attack a protein molecule, it seems reasonable to assume that hemolysis might be the consequence of free radical attack on hemoglobin protein. The results of this study demonstrated that reperfusion following ischemic arrest caused an increase in free hemoglobin and free heme concentrations, simultaneously releasing free iron and generating hydroxyl radicals. In vitro studies using pure hemoglobin indicated that superoxide anion generated by the action of xanthine oxidase on xanthine could release iron from the heme ring and cause deoxygenation of oxyhemoglobin into ferrihemoglobin. This study further demonstrated that before the release of iron from the heme nucleus, oxyhemoglobin underwent deoxygenation to ferrihemoglobin. The released iron can catalyze the Fenton reaction, leading to the formation of cytotoxic hydroxyl radical (OH·). In fact, the formation of OH. in conjunction with hemolysis occurs during cardiac surgery, and when viewed in the light of the in vitro results, it seems likely that oxygen-derived free radicals may cause hemolysis during cardiopulmonary bypass and simultaneously release iron from the heme ring, which can catalyze the formation of OH·.  相似文献   
92.
In Japan, histiocytic necrotizing lymphadenitis (Kikuchi’s disease) is a relatively common reactive lesion affecting lymph nodes, but the histogenesis and pathogenesis of the disease have not been clarified. Alpha-interferon has a role in the body’s defense against, viral infections. Using a polyclonal antibody to human alpha-interferon, we found numerous cells, mainly histiocytes, containing alpha-interferon in affected foci in the lymph nodes from 24 patients with Kikuchi’s disease. Tubuloreticular structures, thought by some authors to be associated with the production of interferon, were detected by electron microscopy in histiocytes, activated lymphocytes and vascular endothelial cells in the affected foci. These results suggested that the formation of tubuloreticular structures is a secondary phenomenon following stimulation by alpha-interferon. Further, the activity of 2′–5′ oligoadenylate synthetase, which is induced by alpha-interferon and enhanced during the early or active stage of viral infection, showed increased levels of activity in the active stage of Kikuchi’s disease and decreased to normal levels in the convalescent stage 2 weeks later. These results suggested the possibility of a viral etiology for Kikuchi’s disease.  相似文献   
93.
在乌拉坦麻醉的大鼠,研究了去甲肾上腺素(NE)在缰核(Hb)引起的心血管效应及其机制。Hb内微量注射NE使平均动脉压和心率呈剂量依赖性增加。用α受体阻断剂酚妥拉明预处理Hb,可明显减弱NE在Hb引起的心血管效应,但β受体阻断剂心得安或生理盐水不引起任何影响。Hb内微量注射海人酸使平均动脉压和心率明显增加,但Hb内微量注射利多卡因则不能引起明显的心血管效应。上述结果表明,Hb内NE在调节心血管活动中起重要作用,而这种效应可能是通过激活α受体使Hb兴奋的结果。  相似文献   
94.
Summary In order to evaluate the frequency of skin sensitivity to Storage Mites and the role of such sensitization in respiratory allergic disease in workers with occupational exposure to stored items we studied 217 dock workers, 93 farmers and 104 white collars.From the results of skin prick tests the sensitization to sole Storage Mites appears significantly higher among people working in docks or farms, compared with a control group. This confirms the role of the working environment in inducing sensitization to Storage Mites. Rhinitis and asthma however affect nearly always (27/29 cases) people with an associated sensitization to House Dust Mites. Further studies are needed to define the allergenic importance of Storage Mites in working environments.  相似文献   
95.
Endochitinases (E.C. 3.2.14, chitinase) are believed to be important in the biochemical defense of plants against chitin-containing fungal pathogens. We introduced a gene for class I (basic) tobacco chitinase regulated by Cauliflower Mosaic Virus 35S-RNA expression signals into Nicotiana sylvestris. The gene was expressed to give mature, enzymatically active chitinase targeted to the intracellular compartment of leaves. Most transformants accumulated extremely high levels of chitinase-up to 120-fold that of non-transformed plants in comparable tissues. Unexpectedly, some transformants exhibited chitinase levels lower than in non-transformed plants suggesting that the transgene inhibited expression of the homologous host gene. Progeny tests indicate this effect is not permanent. High levels of chitinase in transformants did not substantially increase resistance to the chitin-containing fungus Cercospora nicotiana, which causes Frog Eye disease. Therefore class I chitinase does not appear to be the limiting factor in the defense reaction to this pathogen.  相似文献   
96.
Sections of two pollarded parkelms (Ulmus glabra) from Damsgaard, Bergen, west Norway have been studied. Changes in annual ring-width are attributed partly to management, namely pollarding, and partly to pathogenic attacks, probably by Ceratocystis ulmi. The oldest attack on the trees dates back to 1826: so far the oldest known record of Dutch elm disease in Norway. Pollarding may be an important factor in attacks by the pathogen within parkelms. A possible relationship between pollarding, the pathogen and the Neolithic elmfall is suggested.  相似文献   
97.
L‐forms of the halo blight pathogen, Pseudomonas syringae phaseolicola, were maintained in a medium which suppressed cell wall synthesis. These L‐forms, unlike revertants (walled forms derived from unstable L‐forms) and cell walled (parent) organisms, did not elicit a hypersensitive response in tobacco leaves. Association of L‐forms with Phaseolus vulgaris was established by seed imbibition in L‐form suspensions compared with appropriate control treatments (5% mannitol or heat‐killed cells). Seedling emergence and plant growth was not affected by L‐form imbibition. The association was detected by agglutination assays using polyclonal antibody. The L‐form association was localized to the lower shoot tissue and was progressively lost with age of plants. Plants with associated L‐forms had vigour and shoot weights equivalent to controls and showed no disease symptoms. The cell walled form could not be isolated from plants showing positive agglutination. On challenge with the pathogen, plants associated with L‐forms showed significantly less disease symptoms than controls. Stem extracts, from associated plants, were inhibitory to in vitro cultures of both L‐forms and parent forms of Ps. syr. phaseolicola. These results indicate that L‐form associations confer induced systemic resistance to bean plants and might be developed as novel biocontrol systems.  相似文献   
98.
棉株感染枯萎病后的几种生理变化及其与抗病性的关系   总被引:1,自引:0,他引:1  
  相似文献   
99.
鳗鲡赤鳍病病原菌的分离鉴定和耐药性的研究   总被引:6,自引:0,他引:6  
从汕头地区5个养鳗场的患赤鳍病的病鳗中均分离到病原菌是嗜水气单胞菌(Aeromonas hydrophila(chester)stanler),将有毒力的87株病原菌对养鰻场常用抗菌剂进行耐药性试验,结果表明,4种抗菌剂的MIC、MIC_(50)和耐药率分别是:土霉素109.3μg/ml、50.0μg/ml和78.8%;氯霉素123.3μg/ml、63.0μg/ml和90.7%;复方磺胺甲基(口恶)唑(TMP/SMZ)720/3600μg/ml、126/630μg/ml和42.5%;痢特灵79.7μg/ml、63.0μg/ml和65.5%。4种被测抗菌剂的平均MIG分别是对照敏感菌株的109.3,102.7,72和26.6倍。上述试验结果显示了由于滥用药物的严重后果  相似文献   
100.
本研究观察了肾血管性高血压大鼠(RHR)肥大左室的等容峰压-容积关系(PIPVR)和左室压力最大上升速率-容积关系(PRPVR)的曲线特征,并用两曲线的升支斜率E_(max)和dE/dt_(max)及曲线的特征参数评价了RHR(8周)左室的收缩能力及其对异丙肾上腺素的反应性。结果显示,大鼠高血压8周后左室发生明显肥大;与同龄假手术对照大鼠(SOR)相似,RHR的PIPVR和PRPVR也呈指数曲线形式;与SOR比较,RHR左室的PIPVR和PRPVR左上移位,E_(max)、dE/dt_(max)显著增大(P均<0.01),分别增加78%和97%,曲线的特征参数K_1、K_2、B_1和B_2也明显高于SOR(P均<0.05),分别增加37%、32%、25%和57%;灌注异丙肾上腺素(0.94μg/min)后,上述指标的增加幅度均较SOR低(P均<0.05)。结果提示,压力超负荷心肌肥大并不影响PIPVR的非线性特征,基础状态下,RHR肥大左室的收缩能力增强,但对异丙肾上腺素的反应性降低。  相似文献   
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