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After introduction of the first human 7 tesla (7T) system in 1999, 7T MR systems have been employed as one of the most advanced platforms for human MR research for more than 20 years. Currently, two 7T MR models are approved for clinical use in the U.S.A. The approval facilitated introduction of the 7T system, summing up to around 100 worldwide. The approval in Japan is much awaited. As a clinical MR scanner, the 7T MR system is drawing attention in terms of safety.Several large-sized studies on bioeffects have been reported for vertigo, dizziness, motion disturbances, nausea, and others. Such effects might also be found in MR workers and researchers. Frequency and severity of reported bioeffects will be presented and discussed, including their variances. The high resonance frequency and shorter RF wavelength of 7T increase the concern about the safety. Homogeneous RF pulse excitation is difficult even for the brain, and a multi-channel parallel transmit (pTx) system is considered mandatory. However, pTx may create a hot spot, which makes the estimation of specific absorption rate (SAR) to be difficult. The stronger magnetic field of 7T causes a large force of displacement and heating on metallic implants or devices, and the scan of patients with them should not be conducted at 7T. However, there are some opinions that such patients might be scanned even at 7T, if certain criteria are met. This article provides a brief review on the effect of the static magnetic field on humans (MR subjects, workers, and researchers) and neurons, in addition to scan sound, SAR, and metal implants and devices. Understanding and avoiding adverse effects will contribute to the reduction in safety risks and the prevention of incidents.  相似文献   
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构建Loa22基因去信号肽片段原核重组表达载体   总被引:1,自引:0,他引:1  
目的:构建赖型钩端螺旋体OmpA膜蛋白Loa22基因去信号肽片段的原核表达载体,并对其进行克隆表达。方法:实验于2004—12/2005—12在四川大学华西医学中心感染免疫研究室完成。以赖型钩端螺旋体017株基因组DNA为模板,PCR扩增Loa22基因去信号肽片段,亚克隆至原核表达载体pGEX-4T-1,经双酶切、PCR鉴定,筛选出阳性重组质粒克隆。经DNA测序正确后,转化大肠杆菌,利用IPTG进行诱导表达,通过SDS—PAGE鉴定表达产物。结果:PCR获得长516bp的片段。Loa22基因去信号肽片段与pGEX-4T-1的重组质粒构建成功。重组质粒经IPTG诱导后能在大肠杆菌中表达Mr45000的融合蛋白。结论:制备了Loa22基因去信号肽片段原核重组表达载体,为钩体新型疫苗的研究奠定基础。  相似文献   
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To determine the optimal dose of gamma radiation necessary to inhibit T- lymphocyte function and prevent transfusion-acquired graft-versus-host disease (TA-GVHD), a donor plateletpheresis component was initially divided into ten 20-mL samples. One sample was not irradiated, while the other nine samples were treated with gamma radiation at doses ranging from 500 to 4500 cGy. T-lymphocyte function was subsequently measured by mixed lymphocyte cultures and mitogen stimulation assays. The results were assessed in each test by calculating the percentage of inhibition of each irradiated sample as compared to that of the unirradiated sample. The accuracy of the delivered dose of gamma radiation was measured with thermoluminescent dosimeters. It was concluded that a nominal dose of 3000 cGy (actual dose delivered, 2898 cGy) is the appropriate amount of gamma radiation needed to eliminate T- lymphocyte-mediated graft-versus-host disease.  相似文献   
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BACKGROUND: Pantoprazole is a substituted benzimidazole which is a potent inhibitor of gastric acid secretion by its action upon H+, K+- ATPase. METHODS: Pantoprazole 40 mg and 80 mg were compared in a randomized double-blind study in 192 out-patients with stage II or III (Savary-Miller classification) reflux oesophagitis. Patients received either pantoprazole 40 mg (n = 97) or pantoprazole 80 mg (n = 95), once daily before breakfast for 4 weeks. Treatment was extended for a further 4 weeks if the oesophagitis had not healed. RESULTS: After 4 weeks complete healing of the reflux oesophagitis was seen in 78% of protocol-correct patients given pantoprazole 40 mg daily (n = 86), and in 72% in the 80 mg (n = 87) group. The cumulative healing rates after 8 weeks were 95 and 94%, respectively (P > 0.05, Cochran-Mantel- Haenszel), and time until healing of oesophagitis comparable in both groups. Differences between doses were also not significant in an intention-to-treat analysis. Both dosing schedules were well tolerated and the patients experienced remarkable symptom relief. No adverse event or changes in laboratory values of clinical significance could definitely be ascribed to the trial medication. CONCLUSION: The 40 mg pantoprazole dosage is comparable to 80 mg in reflux oesophagitis, both in efficacy and tolerability.  相似文献   
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用RP-HPLC法,以三唑仑为内标,反相C18为分析柱,乙腈—0.01mol·L-1磷酸二氢钠—四甲基乙二胺(46∶54∶0.22v/v)为流动相,磷酸调至pH6.9,检测波长263nm,测定血清和尿中盐酸青藤碱浓度,线性范围分别为6~480ng·mL-1和0.06~3μg·mL-1,平均回收率75.88%和91.35%,日内日间误差小于5%,最低检测浓度血清4ng·mL-1,尿40ng·mL-1。8名健康男性志愿者单次口服盐酸青藤碱片80mg,测定血清及尿浓度,该药符合二室开放模型,体内消除符合一级动力学消除过程,主要药代动力学参数:T1/2α0.791±0.491h,T1/2β9.397±2.425h,Tmax 1.040±0.274h,Cmax246.604±71.165ng·mL-1,AUC 2651.158±1039.050ng·h·mL-1,CL 0.033±0.01ng·mL-1。  相似文献   
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