Analysis of 8-hydroxydeoxyguanosine 5'-monophosphate (8-OH-dGMP) as a reliable marker of cellular oxidative DNA damage after gamma-irradiation

In order to improve 8-hydroxyguanine (8-OH-Gua) detection in DNA, we digested isolated DNA with nuclease P1 and analyzed for 8-hydroxydeoxyguanosine 5'-monophosphate (8-OH-dGMP) using a high-performance liquid chromatography system equipped with an electrochemical detector (HPLC-ECD). The amount of 8-OH-Gua in the DNA was expressed as the ratio of 8-OH-dGMP to deoxycytidine monophosphate (dCMP). Using this analysis, the background level of 8-OH-Gua in DNA from human lung carcinoma cells (A549) was several-fold lower than that obtained by a previous method. A549 cells were exposed to 20-60 Gy of gamma-radiation and an increase in 8-OH-Gua concentration was observed with increasing gamma-ray dose (0.3 residues per 10(7) dCMP per Gy). Moreover, by an immunohistochemical procedure using a commercial FITC-kit, 8-OH-Gua was clearly detected in A549 cells and the fluorescence intensity of cells with oxidative DNA damage increased with the doses of gamma-irradiation. Using an endonuclease nicking assay, we also found that gamma-rays decreased 8-OH-Gua repair activity. The results indicate that 8-OH-dGMP is a useful and sensitive marker for estimating oxidative damage in DNA.     

Minimising stimulator artefacts in electromagnetic flow signals

Simultaneous electrical stimulation of tissue with the measurement of blood flow using an electromagnetic flowmeter system almost invariably results in large flow measurement inaccuracies. These inaccuracies are because the electrical energy from stimulating artefacts is amplified along with the flow signals. The paper describes the building and use of an inexpensive circuit to remove stimulation artefacts from electromagnetic flow measurements.     

独立准直器位置精度对半野联合处剂量的影响

目的:介绍在乳腺癌和鼻咽癌放射治疗中的单一等中心半野联合放疗技术,并对独立准直器位置精度对半野联合处剂量的影响进行研究,提出对策.方法:用带独立准直器的直线加速器,以一个等中心,上下半野技术照射体模,用胶片剂量仪分析半野衔接处剂量分布情况,并将研究结果应用于乳腺癌和鼻咽癌病人的放射治疗.结果:受加速器独立准直器位置精度的影响,半野衔接处可能存在最大不超过2mm的过剂量区或欠剂量区.如果消除该系统误差的影响,则半野衔接处可得到均匀的剂量分布.结论:单一等中心半野联合照射,半野衔接处处于照射靶区,必须重视独立准直器位置精度对衔接处剂量的影响,并加以修正.     

卵巢辐射损伤对大鼠腰椎骨密度和生物力学的影响

目的探讨大鼠卵巢辐射损伤后腰椎骨密度、微结构和生物力学的改变。方法手术暴露大鼠双侧卵巢并应用50Gy的γ射线局部照射,术后90d取大鼠腰椎,DEXA测定骨密度,扫描电镜显示微结构,并行压缩实验检测腰椎最大载荷。结果与假手术组相比,卵巢辐射组大鼠的腰椎骨密度显著减少(P<0.05),骨微结构破坏,生物力学性能下降(P<0.05)。结论卵巢辐射损可导致大鼠腰椎的骨质疏松样改变。     

低能量激光血管内照射治疗脑梗死的临床观察

目的:探讨采用低能量半导体激光血管内照射疗法(intravascular laser irradiation on blood,ILIB)治疗脑梗死的效果及机制.方法:随机选取80例脑梗死患者分为治疗组与对照组,两组各40例,两组患者接受同样的药物治疗,治疗组在上述治疗的基础上,于发病1 d～3 d内,加用半导体激光血管内照射治疗.采用国产半导体激光治疗仪,波长650nm,功率1.5mW～2.0mW.患者平卧,消毒后用静脉留置针穿刺上肢正中静脉或贵要静脉,成功后留置外套管,通过管脑导入激光剂,开启半导体激光治疗仪进行照射治疗.结果:治疗组有效率92.5%,与对照组差异有显著性意义(p＜0.01),治疗组患者临床症状和体征治疗后明显改善.结论:该疗法有调节脂质代谢,改善血液流变学性质,恢复神经传导功能等功效,进而提高脑梗死的治疗效果.     

Magnetophosphenes: a quantitative analysis of thresholds

Low-frequency and transient magnetic fields of moderate flux densities are known to generate visual phenomena, so-called magnetophosphenes. In the present study, time-variable very low frequency (10–50 Hz) electromagnetic fields of moderate flux density (0–40 mT) were used to induce magnetophosphenes. The threshold values for these phosphenes were determined as a function of the frequency of the magnetic field both in normal subjects and colour defective ones. Maximum sensitivity occurred at a frequency of approximately 20–30 Hz, and with broad-spectrum light the threshold flux density was 10–12 mT. The threshola values were found to be dependent upon the intensity and the spectral distribution of the background light. Sensitivity decreased during dark adaptation. In certain respects deutans differed from subjects with normal colour vision. Possible mechanisms for generation of magnetophosphenes are discussed. The present magnetic threshold curves show a close resemblance to corresponding curves obtained by electric stimulation at various frequencies provided the electric thresholds are divided by the a.c. frequency. These problems are under current investigation in our laboratory. This is in full agreement with the assumption that the fluctuating magnetic field affects retinal neurons by inducing currents which polarise synaptic terminals.     

Effect Of Pulsatile Electromagnetic Fields On Blood Viscosity And Coagulation

Ithasbeenprovedthatanumberofdiseasesarerelatedwithabnormalityofbloodviscosityandcoagulationinclinicalresearch.Bloodhyperviscosityandhypercoagulationcauseandaccelearatethedevelopmentofcertaindiseases,deathrateofsomeofwhicharerisingwithyears.Lookingforawaytoreducebloodviscosityandrestrainfasterandstrongercoagulationbecomesasubjectdrawingmoreattention.Theproperseofthisresearchwastofindsuchaway.Intheblood,therearechargrdRBC,WBC,PLT,inorganicions,sothattheremustbesensitiveandcomplicatedresponse…     

Efficacy and safety of anti-CD45–saporin as conditioning agent for RAG deficiency

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