磁化水对小鼠血液过氧化氢酶及谷胱甘肽过氧化物酶活力的影响

将小鼠随机分为饮用磁化水的实验组及饮用自来水的对照组，在组雌鼠８只，雄鼠９只。饲养一个月，测定其血液中的过氧化氢酶（ＣＡＴ）和谷胱甘肽过氧化物酶（ＧＳＨ－ＰＸ）活力。结果雌、雄实验组ＣＡＴ活性均显著高于对照组；雄鼠实验组ＧＳＨ－ＰＸＩ活力显著高于对照组，雌鼠实验组ＧＳＨ－ＰＸ活力与对照组无显著差异。显示饮用一定时间磁化水的雄鼠机体处理自由基能力显著提高。雌鼠处理自由基能力有一定提高。     

超声波对酵母过氧化氢酶活性的影响机理研究

目的 探索超声辐射影响过氧化氢酶（CAT）的催化效果及其作用机理。方法 本试验用不同参数的超声波处理酵母CAT,测定处理前后酶活性变化、催化动力学的变化以及光谱学的变化。结果 试验结果表明。在30℃的条件下,用16kHz、50W的超声波处理酵母CAT2min,酶活力可提高126．35％。经超声波处理后的CAT分子荧光强度有所增加。超声波处理后,CAT的紫外吸收光谱基本不改变,说明超声作用并没有改变CAT的分子构型。而超声波处理后,CAT的紫外差示光谱分别出现正峰和负峰,说明超声波使CAT的分子构象发生了改变。对超声波处理前后的CAT分别进行动力学分析,结果表明超声波处理使酶的米氏常数（Km）和最大反应速度（Vmax）都增大。结论 从试验结果得出结论,适宜参数超声波处理酵母CAT后酶活性升高,可能是超声波改变酶分子的构象所引起。     

稳恒磁场对体外胚胎中脑神经元细胞分化影响的研究

本文利用大鼠胚胎中脑神经细胞作原代微团培养，培养物经不同强度（分别为５ ｍ Ｔ，１０ ｍ Ｔ，２０ｍ Ｔ，３０ ｍ Ｔ，４０ ｍ Ｔ，５０ ｍ Ｔ和６０ ｍ Ｔ）的稳恒磁场作用，研究其对细胞生长和分化的影响，并利用图像分析细胞形态的变化。结果表明：各种强度的稳恒磁场能明显地抑制中脑神经细胞的分化，集落形成率明显减少，且细胞表面的突起和集落间的神经纤维束减少。     

幽门螺杆菌尿素酶A、过氧化氢酶的表达及纯化

目的：探讨重组尿素酶A亚单位（UreA）、过氧化氢酶（KatA）疫苗在防治婴门螺杆菌（HP）感染中的作用。方法：构建表达UreA、KatA的重组质粒,用IPTG诱导表达融合蛋白,并进行SDS－PAGE凝胶电泳及Western blot分析,Bulk GST Purification Module试剂盒纯化UreA和KatA。结果：构建的重组质粒能表达GST－UreA和GST－KatA合蛋白,表达量占细胞总蛋白量的35％和19％,并能与抗GST 发生特异性反应。纯化的UreA、KatA的纯度达95％以上。结论：该工作为进一步的动物免疫实验奠定了基础,该重组疫苗有望在HP感染及其相关疾病的防治中发挥积极作用。     

恒磁场对大鼠血液流变学及一氧化氮含量的影响

本研究通过建立大鼠前脑缺血再灌注损伤模型，然后应用恒磁场进行照射，10天后眼球取血，断头取脑观察其血液流变学指标，N0(一氧化氮)、NOS(一氧化氮合成酶)、GSH—PX(谷胱甘肽过氧化物酶)含量影响。实验结果表明，恒定磁场通过降低血液粘度，改善血液循环状态；降低N0对神经细胞的毒性作用；升高GSH—PX的活力，维持一定量的GSH对血脑屏障的保护作用．减轻缺血后脑水肿，对脑缺血再灌注损伤起到一定的保护作用。     

麻黄素对小鼠心肌组织结构和总抗氧化能力、过氧化氢酶活力的影响

目的探讨麻黄素对小鼠心肌组织的毒性影响。方法 60只小鼠随机分为麻黄素组和对照组,每组各30只,用递增剂量腹腔连续注射麻黄素溶液(0.0315 g/kg、0.0477 g/kg、0.0564 g/kg)和等量的生理盐水15d(每天两次,每次0.2ml),称量检测小鼠体重和心重的变化,用生物显微技术观察心肌组织结构的变化,用比色法检测血浆肌酸激酶(CK)、肌酸激酶同工酶-MB(CK-MB)和心肌组织总抗氧化能力(T-AOC)、过氧化氢酶(CAT)活力及丙二醛(MDA)含量的变化。结果麻黄素组小鼠体重和心重均低于对照组,小鼠心肌组织出现不同程度的损伤,心肌细胞排列紊乱,闰盘间隙增宽,心肌纤维断裂;麻黄素组小鼠血浆CK、CK-MB活性高于对照组(P0.01),心肌组织T-AOC和CAT的活性降低(P0.05或P0.01),MDA含量则升高(P0.01)。结论麻黄素影响小鼠心肌组织结构,可能与心肌组织抗氧化酶活性降低和丙二醛含量升高有关。     

恒磁场对大鼠骨髓间充质干细胞增殖的影响

目的:探讨中心磁场强度为0.2 T的恒磁场对大鼠骨髓间充质干细胞的影响.方法:用全骨髓贴壁法分离大鼠骨髓间充质干细胞,对生长良好的第3代细胞进行中心磁场强度为0.2 T的恒磁场刺激,MTT法测定细胞增殖水平,流式细胞仪法测定细胞周期变化.结果:大鼠骨髓间充质干细胞经磁场刺激5 d后,实验组细胞增殖水平和(S+G2/M)期细胞数量均有不同程度提高,差异有统计学意义(P<0.05).结论:恒磁场能促进体外培养大鼠骨髓间充质干细胞的增殖水平.     

中华眼镜蛇毒对荷人鼻咽癌裸鼠血过氧化氢酶和GSH-PX活性的影响

目的:探讨中华眼镜蛇毒(NNAV)对荷人鼻咽癌(NPC)裸鼠血中过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)活性的影响。方法:采用比色法检测经腹腔注射低、中或高浓度NNAV(1mg／L、5mg／L或10mg／L)的荷人NPC裸鼠血中CAT和GSH-PX活性。结果:荷人NPC裸鼠组血中CAT活性(16450U/L)低于正常裸鼠组(20680U/L)(P＜0.05),而荷瘤裸鼠组血中GSH-PX活性(27670U/L)与正常裸鼠组(28790U/L)相比P＞0.05。低、中和高浓度NNAV治疗后的荷瘤鼠组血中CAT活性(20570U/L、23090U/L、21280U/L)均高于荷瘤鼠组(16450U/L)(P＜0.05),并接近正常水平(20680U/L)(P＞0.05)。同时低、中和高浓度用药组血中GSH-PX活性均不同程度地高于荷瘤鼠组(27670U/L)(P＜0.05),其中高浓度组(37810U/L)明显高于低或中浓度组(29940U/L、30610U/L)(P＜0.05),其血中GSH-PX活性明显高于正常裸鼠组(28790U/L)(P＜0.05)。结论:NNAV的抑瘤作用可能与其提高荷瘤鼠血中CAT和GSH-PX活性有关。     

过氧化氢对血管平滑肌细胞增殖和明胶酶A及其抑制因子基因表达的影响

目的:探讨过氧化氢(H₂O₂)对体外培养大鼠血管平滑肌细胞(VSMC)增殖和明胶酶A(MMP-2)、及其抑制因子(TIMP-2)基因表达的影响。方法:先用四甲基偶氮唑(MTT)法筛选出H₂O₂对VSMC的毒性作用浓度和增殖作用浓度,在此基础上用逆转录聚合酶链反应(RT-PCR)法测定H₂O₂对MMP-2、TIMP-2mRNA表达的影响。结果:H₂O₂浓度大于300μmol/L后显示出对VSMC的致死毒性作用;H₂O₂浓度在0.01-5.0μmol/L内可以刺激VSMC的增殖,且呈时间依赖性;1μmol/LH₂O₂、10μmol/LH₂O₂对MMP-2基因转录有明显的促进作用;不同浓度的H₂O₂对TIMP-2基因转录无明显促进作用。结论:适当浓度的H₂O₂可以促进VSMC的增殖和MMP-2mRNA表达,但对TIMP-2mRNA表达无明显作用,提示H₂O₂参与了血管重塑的不同病理环节。     

Behavioral effects on rats of high strength magnetic fields generated by a resistive electromagnet

It has been reported previously that exposure to static high magnetic fields of 7 T or above in superconducting magnets has behavioral effects on rats. In particular, magnetic field exposure acutely but transiently suppressed rearing and induced walking in tight circles; the direction of circular locomotion was dependent on the rats' orientation within the magnet. Furthermore, when magnet exposure was paired with consumption of a palatable, novel solution, rats acquired a persistent taste aversion. In order to confirm these results under more controlled conditions, we exposed rats to static magnetic fields of 4 to 19.4 T in a 189 mm bore, 20 T resistive magnet. By using a resistive magnet, field strengths could be arbitrary varied from -19.4 to 19.4 T within the same bore. Rearing was suppressed after exposure to 4 T and above; circling was observed after 7 T and above. Conditioned taste aversion was acquired after 14 T and above. The effects of the magnetic fields were dependent on orientation. Exposure to +14 T induced counter-clockwise circling, while exposure to -14 T induced clockwise circling. Exposure with the rostral-caudal axis of the rat perpendicular to the magnetic field produced an attenuated behavioral response compared to exposure with the rostral-caudal axis parallel to the field. These results in a single resistive magnet confirm and extend our earlier findings using multiple superconducting magnets. They demonstrate that the behavioral effects of exposure within large magnets are dependent on the magnetic field, and not on non-magnetic properties of the machinery. Finally, the effects of exposure to 4 T are clinically relevant, as 4 T magnetic fields are commonly used in functional MRI assays.     

Behavioral effects of static high magnetic fields on unrestrained and restrained mice

High-strength static magnetic fields are common tools in clinical imaging, but the behavioral effects are not well characterized. Previous studies on rats showed that fields of 7 T or above produced locomotor circling, conditioned taste aversion (CTA) and c-Fos in vestibular nuclei. To determine the generality of the behavioral effects on a smaller species, we subjected restrained or unrestrained mice to 30-min exposures in a 14.1-T field. Mice were given saccharin immediately prior to magnet or sham exposure on 3 consecutive days. All mice exposed to the magnet developed a CTA, and a significant number displayed tight circling and suppression of rearing. Unrestrained mice exhibited larger effects than restrained mice. These effects, similar to the effects in rats, may be the result of a vestibular disturbance caused by the magnetic field.     

工频磁场对细胞蛋白质酪氨酸磷酸化影响的研究

目的;研究５０Ｈｚ工频磁场绎细胞浆蛋白质酪氨酸磷酸化的以初步工频磁场生物效 有关细胞信息转导的机制。方法;对分别经两个不同强度的工频磁场作不同时间辐照处理后的细胞,提取其胞浆蛋白质,定量后,以Ｗｅｓｔｅｒｎ ｂｌｏｔ方法测定并比较细胞胞浆蛋白质酪氨酸磷酸化的程度。     

Effects of static magnetic fields on the voltage-gated potassium channel currents in trigeminal root ganglion neurons

To evaluated the effects of moderate-intensity static magnetic fields (SMF) on two types of voltage-gated potassium channel (VGPC) currents: I(K,A) and I(K,V), whole-cell patch-clamp experiments were conducted on acute dissociated rat trigeminal root ganglion (TRG) neurons. The results demonstrated that 125 mT SMF could influence the inactivation kinetics of these two VGPC currents by altering the inactivation rate and velocity. No significant change was observed in the activation properties. These findings supported the hypothesis that biological membrane would be deformed in moderate-intensity SMF and the physiological characteristics of ion channels on the membrane would be influenced. The mechanism underlying the different effects of SMF on the I(K,A) and I(K,V) inactivation was also discussed.     

Influence of strong magnetic fields on genetic endpoints in Tradescantia tetrads and stamen hairs

Inflorescences from Tradescantia clones 4430 and 02 were subjected to mean magnetic field intensiteis of 0.16 or 0.76 to 0.78 tesla for 6 to 11 days. Following exposures to both intensities, damage to pollen mother cell chromosomes at early prophase was determined by scoring the frequency of micronuclei in early tetrads. Pink mutations in stamen hair cells of clone 4430 were scored for 15 days after a 6-day exposure to the higher intensity level while clone 02 was scored during and for 6 days after an 11-day exposure to the 0.16 tesla field. Comparison of micronuclei results from exposed groups to those for control groups that were scored concurrently showed that there was no significant difference in frequency for either clone or either field intensity (P values in contingency table analyses were between 0.42 and 0.6); similarly, pink mutation frequencies for clone 4430 exposed and control groups did not differ significantly (a contingency test yielded χ² = 1.4 and P = 0.26). Comparisons of pink mutation frequencies during the first 6 days of clone 02 exposure to those in the period when an effect should be greatest (days 7 through 17 revealed no significant difference (χ² = 2.6 and P = 0.1) between the two scoring periods, through frequencies were higher during the early scoring period.     

Spatial and temporal variations in the magnetic fields produced by human gastrointestinal activity

Magnetoenterography (MENG) is a new, non-invasive technique that measures gastrointestinal magnetic signals near the body surface. This study was undertaken to evaluate the temporal and spatial characteristics of the magnetic signals generated by gastric and duodenal slow wave activity. The gastrointestinal magnetic fields of eight normal subjects were measured for 60 minutes in both the fasting and fed state using 36 magnetic sensors simultaneously. The results were displayed as a succession of maps over time showing the temporal evolution of the spatial distribution of the signal over the upper abdomen. In all subjects, slow wave activity of the stomach centred at 3.0 +/- 0.5 cycles min-1 in both the fasting and fed state was observed. The duodenal signal at 11.0 +/- 1.0 cycles min-1 was observed in four subjects. The spatial distribution of these two signals is distinctly different. The observed spatial and temporal variations are described in terms of a model used previously to explain the potentials observed in electrogastrography (EGG).     

Spatial and temporal variations in the magnetic fields produced by human gastrointestinal activity

Magnetoenterography (MENG) is a new, non-invasive technique that measures gastrointestinal magnetic signals near the body surface. This study was undertaken to evaluate the temporal and spatial characteristics of the magnetic signals generated by gastric and duodenal slow wave activity. The gastrointestinal magnetic fields of eight normal subjects were measured for 60 minutes in both the fasting and fed state using 36 magnetic sensors simultaneously. The results were displayed as a succession of maps over time showing the temporal evolution of the spatial distribution of the signal over the upper abdomen. In all subjects, slow wave activity of the stomach centred at 3.0±0.5 cycles min⁻¹ in both fasting and fed state was observed. The duodenal signal at 11.0±1.0 cycles min⁻¹ was observed in four subjects. The spatial distribution of these two signals is distinctly different. The observed spatial and temporal variations are described in terms of a model used previously to explain the potentials observed in electrogastrography (EGG).     

Theoretical model for investigating the magnetic and electric fields produced during pulsed magnetic field therapy for nonunion of the tibia

Pulsed magnetic field therapy for tibial nonunion has become an established orthopaedic procedure in many centres. The field is generated by passing pulses of current through coils positioned one each side of the limb but the magnitudes of the magnetic and induced electric fields produced are not usually known. The paper describes a method of calculating the fields that gives good agreement between theory and measurement. An improved model of a bone in a limb has been developed and this model predicts that the peak induced electric field close to the fracture site is between 0·03 and 0·6 Vm⁻¹, depending on which of the many clinically tested coil systems is used. The effect of changing geometry and the contribution of the outer surface of the limb are examined, and the implications for future experimental work are discussed.     

Biological effects of static magnetic fields on the microcirculatory blood flowin vivo: a preliminary report

There have been few studies of the effect of static magnetic fields on microcirculatory haemodynamics in vivo. The rat skinfold transparent chamber technique was used, which provides an excellent means of observing and quantifying direct in vivo microvascular haemodynamic responses to static magnetic fields up to 8 T. An intravital videomicroscope was used to measure the changes in blood flow before and after exposure to a magnetic field for 20 min in a horizontal type superconducting magnet with a bore 100 mm in diameter and 700 mm long. After exposure, microcirculatory blood flow showed an initial increase for about 5 min followed by a gradual decrease and a return to the control value. It is hypothesised that these changes represent rebound hyperaemia following reduced blood flow during exposure.     

Volume conductor effects on the spatial resolution of magnetic fields and electric potentials from gastrointestinal electrical activity

An analysis of the relative capabilities of methods for magnetic and electric detection of gastrointestinal electrical activity is presented. The model employed is the first volume conductor model for magnetic fields from GEA to appear in the literature. A mathematical model is introduced for the electric potential and magnetic field from intestinal electrical activity in terms of the spatial filters that relate the bioelectric sources with the external magnetic fields and potentials. The forward spatial filters are low-pass functions of spatial frequency, so more superficial external fields and potentials contain less spatial information than fields and potentials near the source. Inverse spatial filters, which are reciprocals of the forward filters, are high-pass functions and must be regularised by windowing. Because of the conductivity discontinuities introduced by low-conductivity fat layers in the abdomen, the electric potentials recorded outside these layers required more regularisation than the magnetic fields, and thus, the spatial resolution of the magnetic fields from intestinal electrical activity is higher than the spatial resolution of the external potentials. In this study, two smooth muscle sources separated by 5 cm were adequately resolved magnetically, but not resolved electrically. Thus, sources are more accurately localized and imaged using magnetic measurements than using measurements of electric potential.