• 【1.5T轨道的表面线圈磁共振成像。】 复制标题 收藏 收藏
    影响因子 :
    发表时间:1988-11-01
    来源期刊:Rofo
    DOI:10.1055/s-2008-1048391 复制DOI
    作者列表:Wilms G,Marchal G,Decrop E,van Hecke P,Baert A,Dralands G
    BACKGROUND & AIMS: :MRI of the orbit at 1.5-Tesla was performed in 5 healthy volunteers and 30 patients with a variety of pathological intraocular or intraconal conditions. Major advantages of MRI over CT include higher spatial resolution, higher tissue contrast, possibility of direct multiplanar imaging, absence of bony and dental artifacts, and of ionising radiation. Specific indications of MRI in orbital pathology concern differentiation of uveal melanoma from subretinal haemorrhage, identification of lesions of the orbital apex, the orbital fissure or the optic canal, differentiation of inflammatory pseudotumour from malignant lesions, determination of the posterior extension of lesions of the optic nerve, and detection of abnormal flow in normal or hypertrophic intraorbital vessels. Limitations are due to motion artifacts on T2 weighted sequences, less accurate visualisation of calcification, poor specificity of some findings, and absence of signal from cortical bone.
    背景与目标: :在5名健康志愿者和30名患有各种病理性眼内或圆锥内疾病的患者中进行了1.5-Tesla眼眶的MRI检查。 MRI优于CT的主要优点包括更高的空间分辨率,更高的组织对比度,直接多平面成像的可能性,无骨和牙齿伪影以及电离辐射。眼眶病变的MRI特定指征涉及葡萄膜黑色素瘤与视网膜下出血的区别,眼眶顶点,眼眶裂孔或视神经管的病变的识别,炎性假瘤与恶性病变的区别,对视神经病变的向后扩展的确定神经,以及正常或肥大的眶内血管中异常血流的检测。局限性是由于T2加权序列上的运动伪影,钙化的可视化效果较差,某些发现的特异性差以及皮质骨信号缺失所致。
  • 【人工卷曲螺旋蛋白单层的力调制电导。】 复制标题 收藏 收藏
    DOI:10.1002/bip.22181 复制DOI
    作者列表:Atanassov A,Hendler Z,Berkovich I,Ashkenasy G,Ashkenasy N
    BACKGROUND & AIMS: :Studies of charge transport through proteins bridged between two electrodes have been the subject of intense research in recent years. However, the complex structure of proteins makes it difficult to elucidate transport mechanisms, and the use of simple peptide oligomers may be an over simplified model of the proteins. To bridge this structural gap, we present here studies of charge transport through artificial parallel coiled-coil proteins conducted in dry environment. Protein monolayers uniaxially oriented at an angle of ∼ 30° with respect to the surface normal were prepared. Current voltage measurements, obtained using conductive-probe atomic force microscopy, revealed the mechano-electronic behavior of the protein films. It was found that the low voltage conductance of the protein monolayer increases linearly with applied force, mainly due to increase in the tip contact area. Negligible compression of the films for loads below 26 nN allowed estimating a tunneling attenuation factor, β(0) , of 0.5-0.6 Å(-1) , which is akin to charge transfer by tunneling mechanism, despite the comparably large charge transport distance. These studies show that mechano-electronic behavior of proteins can shed light on their complex charge transport mechanisms, and on how these mechanisms depend on the detailed structure of the proteins. Such studies may provide insightful information on charge transfer in biological systems.
    背景与目标: 近年来,通过跨两个电极的蛋白质进行电荷传输的研究一直是研究的重点。但是,蛋白质的复杂结构使得难以阐明转运机制,并且简单肽寡聚物的使用可能是蛋白质的过度简化模型。为了弥合这种结构缺口,我们在这里介绍了在干燥环境中通过人工平行卷曲螺旋蛋白进行电荷传输的研究。制备相对于表面法线单轴取向约30°的蛋白质单分子层。使用导电探针原子力显微镜获得的当前电压测量结果揭示了蛋白质膜的机械电子行为。已经发现,蛋白质单层的低电导率随着施加的力线性增加,这主要是由于尖端接触面积的增加。对于低于26 nN的负载,薄膜的压缩可忽略不计,因此可以估算出隧穿衰减因子β(0)为0.5-0.6Å(-1),尽管电荷传输距离相对较大,但类似于通过隧穿机制进行的电荷转移。这些研究表明,蛋白质的机电行为可以阐明其复杂的电荷传输机制,以及这些机制如何依赖于蛋白质的详细结构。这样的研究可以提供有关生物系统中电荷转移的有见地的信息。
  • 【含有109B的卷曲螺旋结构域是HIF1α调控的基因,对人类神经胶质瘤的进展至关重要。】 复制标题 收藏 收藏
    DOI:10.1186/s12967-017-1266-9 复制DOI
    作者列表:Xu R,Han M,Xu Y,Zhang X,Zhang C,Zhang D,Ji J,Wei Y,Wang S,Huang B,Chen A,Zhang Q,Li W,Sun T,Wang F,Li X,Wang J
    BACKGROUND & AIMS: BACKGROUND:The coiled-coil domain is a structural motif found in proteins that participate in a variety of biological processes. Aberrant expression of such proteins has been shown to be associated with the malignant behavior of human cancers. In this study, we investigated the role of a specific family member, coiled-coil domain containing 109B (CCDC109B), in human gliomas. METHODS AND RESULTS:We confirmed that CCDC109B was highly expressed in high grade gliomas (HGG; WHO III-IV) using immunofluorescence, western blot analysis, immunohistochemistry (IHC) and open databases. Through Cox regression analysis of The Cancer Genome Atlas (TCGA) database, we found that the expression levels of CCDC109B were inversely correlated with patient overall survival and it could serve as a prognostic marker. Then, a serious of cell functional assays were performed in human glioma cell lines, U87MG and U251, which indicated that silencing of CCDC109B attenuated glioma proliferation and migration/invasion both in vitro and in vivo. Notably, IHC staining in primary glioma samples interestingly revealed localization of elevated CCDC109B expression in necrotic areas which are typically hypoxic. Moreover, small interfering RNA (siRNA) and specific inhibiters of HIF1α led to decreased expression of CCDC109B in vitro and in vivo. Transwell assay further showed that CCDC109B is a critical factor in mediating HIF1α-induced glioma cell migration and invasion. CONCLUSION:Our study elucidated a role for CCDC109B as an oncogene and a prognostic marker in human gliomas. CCDC109B may provide a novel therapeutic target for the treatment of human glioma.
    背景与目标: 背景:卷曲螺旋结构域是在参与多种生物学过程的蛋白质中发现的结构基序。已经表明这种蛋白质的异常表达与人类癌症的恶性行为有关。在这项研究中,我们调查了一个特定的家庭成员,包含109B(CCDC109B)的卷曲螺旋域在人类神经胶质瘤中的作用。
    方法和结果:我们使用免疫荧光,免疫印迹分析,免疫组化(IHC)和开放式数据库证实了CCDC109B在高级别胶质瘤(HGG; WHO III-IV)中高表达。通过癌症基因组图谱(TCGA)数据库的Cox回归分析,我们发现CCDC109B的表达水平与患者的总体生存率呈负相关,并且可以作为预后的标志物。然后,在人神经胶质瘤细胞系U87MG和U251中进行了严重的细胞功能测定,这表明CCDC109B的沉默在体外和体内均减弱了神经胶质瘤的增殖和迁移/侵袭。值得注意的是,原发性神经胶质瘤样本中的IHC染色有趣地揭示了在通常缺氧的坏死区域中CCDC109B表达升高的定位。此外,小的干扰RNA(siRNA)和HIF1α的特异性抑制剂导致CCDC109B在体外和体内的表达降低。 Transwell分析进一步表明,CCDC109B是介导HIF1α诱导的神经胶质瘤细胞迁移和侵袭的关键因素。
    结论:我们的研究阐明了CCDC109B在人类神经胶质瘤中作为癌基因和预后标志物的作用。 CCDC109B可为治疗人脑胶质瘤提供新的治疗靶标。
  • 【腔内腹腔动脉瘤修复后10年,致命的盘绕迁移到胃中。】 复制标题 收藏 收藏
    DOI:10.1016/j.jvir.2006.10.003 复制DOI
    作者列表:Dinter DJ,Rexin M,Kaehler G,Neff W
    BACKGROUND & AIMS: :Celiac trunk aneurysms are rare and can be treated with coil embolization. Migration of the coil with erosion of the arterial wall and further perforation to an extravascular structure, although infrequent, can occur. The authors describe a lethal aortogastric fistula in a patient who had undergone embolization of a celiac trunk aneurysm with tungsten coils and alcohol prolamine solution 10 years earlier. Gastroscopy, performed due to acute hematemesis, showed the coil placed 10 years previously inside the stomach without active bleeding. Two days later, the patient died of a recurrent gastrointestinal bleeding. Autopsy showed abscess formation at the celiac trunk resulting in an aortogastric fistula. The authors discuss the possible cause of this remote complication of the embolotherapy.
    背景与目标: :腹腔干动脉瘤很少见,可以用线圈栓塞治疗。尽管不常见,但可能会发生线圈的迁移,并伴有动脉壁的侵蚀,并进一步穿孔至血管外结构。作者描述了在10年前接受钨丝线圈和醇溶谷蛋白胺溶液栓塞的腹腔干动脉瘤栓塞的患者中的致死性主动脉瘘。由于急性呕血而进行的胃镜检查显示,线圈在胃内放置了10年之久,而没有活动性出血。两天后,患者死于胃肠道出血。尸检显示在腹腔干处形成脓肿,导致主动脉瘘。作者讨论了栓塞治疗这种远程并发症的可能原因。
  • 【骨髓来源的细胞中Rho相关的含卷曲螺旋激酶2缺乏导致胆固醇外排增加和动脉粥样硬化减少。】 复制标题 收藏 收藏
    DOI:10.1161/CIRCULATIONAHA.111.086041 复制DOI
    作者列表:Zhou Q,Mei Y,Shoji T,Han X,Kaminski K,Oh GT,Ongusaha PP,Zhang K,Schmitt H,Moser M,Bode C,Liao JK
    BACKGROUND & AIMS: BACKGROUND:Macrophages play a central role in the development of atherosclerosis. However, the signaling pathways that regulate their function are not well understood. The Rho-associated coiled-coil-containing kinases (ROCK1 and ROCK2) are serine-threonine protein kinases that are involved in the regulation of the actin cytoskeleton. Recent studies suggest that ROCK1 in macrophages and bone marrow-derived cells mediates atherogenesis. However, a similar role for ROCK2 in the pathogenesis of atherosclerosis has not been determined. METHODS AND RESULTS:The bone marrows from wild-type, ROCK2(+/-), and ROCK2(-/-) mice were transplanted into irradiated recipient low-density lipoprotein receptor(-/-) mice, and atherosclerosis was induced with a 16-week high-cholesterol diet. Compared with wild-type bone marrow-transplanted mice, ROCK2(+/-) bone marrow-transplanted and ROCK2(-/-) bone marrow-transplanted mice showed substantially less lipid accumulation in the aorta (8.46±1.42% and 9.80±2.34% versus 15.64±1.89%; P<0.01 for both) and decreased atherosclerotic lesions in the subaortic sinus (158.1±44.4 and 330.1±109.5×10(3)μm(2) versus 520.2±125.7×10(3)μm(2); P<0.01 for both). These findings correlated with decreased foam cell formation (2.27±0.57 versus 4.10±0.3; P<0.01) and increased cholesterol efflux (17.65±0.6 versus 9.75±0.8; P<0.05) in ROCK2-deficient mice that are mediated, in part, through the peroxisome proliferator-activated receptor-γ/liver X receptor/ATP-binding cassette transporter A1 pathway in macrophages. CONCLUSIONS:ROCK2 contributes to atherosclerosis, in part, by inhibiting peroxisome proliferator-activated receptor-γ-mediated reverse cholesterol transport in macrophages, which contributes to foam cell formation. These findings suggest that inhibition of ROCK2 in macrophages may have therapeutic benefits in preventing the development of atherosclerosis.
    背景与目标: 背景:巨噬细胞在动脉粥样硬化的发展中起着核心作用。但是,调节其功能的信号通路尚不完全清楚。 Rho相关的含有螺旋线圈的激酶(ROCK1和ROCK2)是丝氨酸-苏氨酸蛋白激酶,参与肌动蛋白细胞骨架的调节。最近的研究表明巨噬细胞和骨髓来源的细胞中的ROCK1介导动脉粥样硬化。然而,尚未确定ROCK2在动脉粥样硬化的发病机理中的类似作用。
    方法和结果:将野生型,ROCK2(/-)和ROCK2(-/-)小鼠的骨髓移植到受辐照的低密度脂蛋白受体(-/-)小鼠中,用16诱导了动脉粥样硬化周高胆固醇饮食。与野生型骨髓移植小鼠相比,ROCK2(/-)骨髓移植和ROCK2(-/-)骨髓移植小鼠在主动脉中的脂质蓄积少得多(8.46±1.42%和9.80±2.34%与15.64±1.89%;两者均P <0.01)和主动脉下窦动脉粥样硬化病变减少(158.1±44.4和330.1±109.5×10(3)μm(2)与520.2±125.7×10(3)μm(2) ; P均<0.01)。这些发现与部分介导了ROCK2缺陷的小鼠的泡沫细胞形成减少(2.27±0.57对4.10±0.3; P <0.01)和胆固醇外排增加(17.65±0.6对9.75±0.8; P <0.05)相关。通过过氧化物酶体增殖物激活受体-γ/肝X受体/ ATP结合盒转运蛋白A1途径在巨噬细胞中。
    结论:ROCK2部分通过抑制过氧化物酶体增殖物激活的受体-γ介导的胆固醇在巨噬细胞中的逆向转运而导致动脉粥样硬化,这有助于泡沫细胞的形成。这些发现表明,巨噬细胞中ROCK2的抑制在预防动脉粥样硬化的发展中可能具有治疗益处。
  • 【[使用直接经皮穿刺椎动脉穿刺栓塞椎动脉瘤的技术报告]。】 复制标题 收藏 收藏
    DOI:10.11477/mf.1436203776 复制DOI
    作者列表:Sasaki K,Yoshida M,Mino M,Tashiro R
    BACKGROUND & AIMS: :Although direct puncture of the cervical vertebral artery(VA)is not commonly performed in neuroendovascular therapy, it is sometimes inevitable for procedural or technical reasons. We report a case of a ruptured VA aneurysm that required direct cervical VA puncture for treatment. A 79-year-old man was transferred to our hospital with the diagnosis of subarachnoid hemorrhage. Cerebral angiography revealed a right VA-posterior inferior cerebellar artery aneurysm. The aneurysm showed downward projection due to retrograde flow of the right VA caused by chronic occlusion of the right subclavian artery. For endovascular treatment, the approach through the VA union via the left VA was thought to be most appropriate;however, the left VA was very tortuous and the microcatheter could not cross the VA union. We performed percutaneous direct puncture of the left cervical VA. An 18-G intravenous catheter needle(Surflo®)was advanced and set into the C5/6 segment of the VA under biplane fluoroscopic road-mapping guidance. The microcatheter reached the aneurysm and coil embolization was successfully performed. The patient was kept intubated under general anesthesia overnight, to monitor for cervical subcutaneous hematoma. Several procedures for direct VA puncture have been reported. The major problem is the difficulty with hemostasis and maintenance of the airway is important. Although the indication is limited due to the difficulty of adjunctive techniques and postoperative antithrombotic therapy, direct VA puncture under biplane fluoroscopic guidance was useful in this case.
    背景与目标: :尽管在神经内血管治疗中通常不直接进行颈椎动脉(VA)的直接穿刺,但出于手术或技术原因,有时还是不可避免的。我们报告了一例需要直接进行宫颈VA穿刺治疗的VA动脉瘤破裂的病例。一名79岁男子被转移到我院诊断为蛛网膜下腔出血。脑血管造影显示右小脑后下动脉瘤。由于右锁骨下动脉的慢性闭塞引起的右VA逆行流动,动脉瘤显示出向下的投影。对于血管内治疗,认为最合适的方法是通过左VA通过VA联合;但是,左VA曲折,微导管无法穿过VA联合。我们对左颈VA进行了经皮直接穿刺。在双平面透视镜下引导下,将18G静脉导管针(Surflo ®)推进并置于VA的C5 / 6段。微导管达到了动脉瘤,并成功进行了线圈栓塞术。病人在全身麻醉下插管过夜,以监测宫颈皮下血肿。已经报道了几种直接进行VA穿刺的方法。主要问题是止血困难,气道的维护很重要。尽管由于辅助技术和术后抗血栓治疗的困难而使适应症受到限制,但在这种情况下,在双平面荧光镜引导下直接进行VA穿刺是有用的。
  • 【TMS线圈定位/保持系统,用于与fMRI交错的MR图像引导TMS。】 复制标题 收藏 收藏
    DOI:10.1016/s1388-2457(03)00232-3 复制DOI
    作者列表:Bohning DE,Denslow S,Bohning PA,Walker JA,George MS
    BACKGROUND & AIMS: OBJECTIVE:Transcranial magnetic stimulation (TMS) can be interleaved with fMRI to visualize regional brain activity in response to direct, non-invasive, cortical stimulation, making it a promising tool for studying brain function. A major practical difficulty is accurately positioning the TMS coil within the MRI scanner for stimulating a particular area of brain cortex. The objective of this work was to design and build a self-contained hardware/software system for MR-guided TMS coil positioning in interleaved TMS/fMRI studies. METHODS:A compact, manually operated, articulated TMS coil positioner/holder with 6 calibrated degrees of freedom was developed for use inside a cylindrical RF head coil, along with a software package for transforming between MR image coordinates, MR scanner space coordinates, and positioner/holder settings. RESULTS:Phantom calibration studies gave an accuracy for positioning within setups of dx=+/-1.9 mm, dy=+/-1.4 mm, dz=+/-0.8 mm and a precision for multiple setups of dx=+/-0.8 mm, dy=+/-0.1 mm, dz=+/-0.1 mm. CONCLUSIONS:This self-contained, integrated MR-guided TMS system for interleaved TMS/fMRI studies provides fast, accurate location of motor cortex stimulation sites traditionally located functionally, and a means of consistent, anatomy-based TMS coil positioning for stimulation of brain areas without overt response.
    背景与目标: 目的:经颅磁刺激(TMS)可以与功能磁共振成像相交错,以可视化对直接,非侵入性皮层刺激的反应,从而使其成为研究脑功能的有前途的工具。一个主要的实际困难是将TMS线圈准确地定位在MRI扫描仪内,以刺激大脑皮层的特定区域。这项工作的目的是为交错式TMS / fMRI研究中的MR引导TMS线圈定位设计并构建一个独立的硬件/软件系统。
    方法:开发了具有6个校准自由度的紧凑型手动铰接式TMS线圈定位器/支架,以在圆柱形RF头线圈内部使用,以及用于在MR图像坐标,MR扫描仪空间坐标和定位器之间转换的软件包/ holder设置。
    结果:幻像校准研究提供了在dx = /-1.9 mm,dy = /-1.4 mm,dz = /-0.8 mm设置中的定位精度以及在dx = /-0.8 mm,dy = /的多个设置中的定位精度。 -0.1毫米,dz = /-0.1毫米。
    结论:此独立的,集成的MR导引的TMS系统可进行TMS / fMRI交错研究,可快速,准确地定位传统功能性定位的运动皮层刺激部位,并提供一致的基于解剖的TMS线圈定位来刺激大脑区域没有明显的反应。
  • 【线圈栓塞后4周单侧多发性脑水肿的病例】 复制标题 收藏 收藏
    DOI:10.11477/mf.1436204148 复制DOI
    作者列表:Torii J,Tanei T,Naito T,Katoh T,Ishii K,Tsukamoto E,Hasegawa T
    BACKGROUND & AIMS: :Coil embolization for cerebral aneurysms can lead to various complications, such as aneurysm rupture and cerebral embolism. In recent years, foreign substance embolisms-caused by peeling off of coating materials from therapeutic devices-have been described. We report here a case of unilateral multiple cerebral edema four weeks after coil embolization. A 44-year-old woman presented with a subarachnoid hemorrhage from a right internal carotid-posterior communicating artery aneurysm, for which coil embolization was performed. Four weeks after the embolization, she developed numbness in the left side of her mouth and in her left upper extremity. Magnetic resonance images showed multiple edematous lesions in the right cerebral hemisphere. Subsequent treatment with steroids improved her symptoms and edematous cerebral lesions. Although definitive diagnosis by biopsy was not performed, her clinical course and imaging findings resembled a foreign substance embolism by hydrophilic coating. It is important to note that delayed cerebral edema due to foreign substance embolisms might occur after endovascular treatments.
    背景与目标: :脑动脉瘤的线圈栓塞可导致多种并发症,例如动脉瘤破裂和脑栓塞。近年来,已经描述了由于从治疗装置上剥离涂层材料而引起的异物栓塞。我们在这里报告了线圈栓塞后四周单侧多发性脑水肿的病例。一名44岁的女性因右颈内-后交通动脉瘤出现蛛网膜下腔出血,对其进行了线圈栓塞术。栓塞后四周,她的嘴左侧和左上肢出现麻木感。磁共振图像显示右脑半球有多处水肿性病变。随后使用类固醇的治疗改善了她的症状和脑水肿。尽管没有进行活检的明确诊断,但她的临床过程和影像学表现类似于亲水涂层的异物栓塞。重要的是要注意,在进行腔内治疗后,可能会因异物栓塞而导致延迟性脑水肿。
  • 【用于7 T时MRI的宽边分体式环形谐振器线圈。】 复制标题 收藏 收藏
    DOI:10.1109/TMI.2013.2253488 复制DOI
    作者列表:Freire MJ,Lopez MA,Meise F,Algarin JM,Jakob PM,Bock M,Marques R
    BACKGROUND & AIMS: :A coil design termed as broadside-coupled loop (BCL) coil and based on the broadside-coupled split ring resonator (BC-SRR) is proposed as an alternative to a conventional loop design at 7T. The BCL coil has an inherent uniform current which assures the rotational symmetry of the radio-frequency field around the coil axis. A comparative analysis of the signal-to-noise ratio provided by BCL coils and conventional coils has been carried out by means of numerical simulations and experiments in a 7T whole body system.
    背景与目标: :提出了一种称为宽边耦合环路(BCL)线圈并且基于宽边耦合裂环谐振器(BC-SRR)的线圈设计,作为7T常规环路设计的替代方案。 BCL线圈具有固有的均匀电流,可确保射频场围绕线圈轴的旋转对称性。通过在7T全身系统中进行数值模拟和实验,对BCL线圈和常规线圈提供的信噪比进行了比较分析。
  • 【在酿酒酵母中,端粒和交配型沉默需要Sir4 C末端卷曲螺旋。】 复制标题 收藏 收藏
    DOI:10.1016/j.jmb.2003.09.066 复制DOI
    作者列表:Murphy GA,Spedale EJ,Powell ST,Pillus L,Schultz SC,Chen L
    BACKGROUND & AIMS: :Saccharomyces cerevisiae Sir4p plays important roles in silent chromatin at telomeric and silent mating type loci. The C terminus of Sir4p (Sir4CT) is critical for its functions in vivo because over-expression or deletion of Sir4CT fragments disrupts normal telomeric structure and abolishes the telomere position effect. The 2.5A resolution X-ray crystal structure of an Sir4CT fragment (Sir4p 1217-1358) reveals a 72 residue homodimeric, parallel coiled coil, burying an extensive 3600A(2) of surface area. The crystal structure is consistent with results of protein cross-linking and analytical ultracentrifugation results demonstrating that Sir4CT exists as a dimer in solution. Disruption of the coiled coil in vivo by point mutagenesis results in total derepression of telomeric and HML silent mating marker genes, suggesting that coiled coil dimerization is essential for Sir4p-mediated silencing. In addition to the coiled coil dimerization interface (Sir4CC interface), a crystallographic interface between pairs of coiled coils is significantly hydrophobic and buries 1228A(2) of surface area (interface II). Remarkably, interface II mutants are deficient in telomeric silencing but not in mating type silencing in vivo. However, point mutants of interface II do not affect the oligomerization state of Sir4CT in solution. These results are consistent with the hypothesis that interface II mimics a protein interface between Sir4p and one of its protein partners that is essential for telomeric silencing but not mating type silencing.
    背景与目标: :酿酒酵母Sir4p在端粒和沉默交配型基因座的沉默染色质中起重要作用。 Sir4p(Sir4CT)的C端对其体内功能至关重要,因为Sir4CT片段的过度表达或缺失会破坏正常的端粒结构并消除端粒的位置效应。 Sir4CT片段(Sir4p 1217-1358)的2.5A分辨率X射线晶体结构揭示了72个残基的同二聚体,平行盘绕的线圈,掩埋了表面积较大的3600A(2)。晶体结构与蛋白质交联的结果和分析超离心结果一致,这表明Sir4CT在溶液中以二聚体形式存在。通过点诱变在体内盘绕线圈的破坏导致端粒和HML沉默交配标记基因完全被阻抑,这表明盘绕线圈二聚化对于Sir4p介导的沉默至关重要。除了卷曲的线圈二聚化界面(Sir4CC界面)外,成对的卷曲线圈之间的晶体学界面明显疏水,并掩埋了表面积(界面II)1228A(2)。值得注意的是,界面II突变体在体内端粒沉默不足,但在交配型沉默方面却不足。但是,界面II的点突变体不会影响溶液中Sir4CT的低聚状态。这些结果与接口II模仿Sir4p及其蛋白伴侣之一之间的蛋白接口这一假设相符,这对于端粒沉默而不是交配型沉默是必不可少的。
  • 【使用3T临床扫描仪和多阵列线圈为多动物腹部MR成像量身定制的强度校正方法。】 复制标题 收藏 收藏
    DOI:10.2463/mrms.2012-0038 复制DOI
    作者列表:Mitsuda M,Yamaguchi M,Nakagami R,Furuta T,Sekine N,Niitsu M,Moriyama N,Fujii H
    BACKGROUND & AIMS: PURPOSE:Simultaneous magnetic resonance (MR) imaging of multiple small animals in a single session increases throughput of preclinical imaging experiments. Such imaging using a 3-tesla clinical scanner with multi-array coil requires correction of intensity variation caused by the inhomogeneous sensitivity profile of the coil. We explored a method for correcting intensity that we customized for multi-animal MR imaging, especially abdominal imaging. METHOD:Our institutional committee for animal experimentation approved the protocol. We acquired high resolution T₁-, T₂-, and T₂*-weighted images and low resolution proton density-weighted images (PDWIs) of 4 rat abdomens simultaneously using a 3T clinical scanner and custom-made multi-array coil. For comparison, we also acquired T₁-, T₂-, and T₂*-weighted volume coil images in the same rats in 4 separate sessions. We used software created in-house to correct intensity variation. We applied thresholding to the PDWIs to produce binary images that displayed only a signal-producing area, calculated multi-array coil sensitivity maps by dividing low-pass filtered PDWIs by low-pass filtered binary images pixel by pixel, and divided uncorrected T₁-, T₂-, or T₂*-weighted images by those maps to obtain intensity-corrected images. We compared tissue contrast among the liver, spinal canal, and muscle between intensity-corrected multi-array coil images and volume coil images. RESULTS:Our intensity correction method performed well for all pulse sequences studied and corrected variation in original multi-array coil images without deteriorating the throughput of animal experiments. Tissue contrasts were comparable between intensity-corrected multi-array coil images and volume coil images. CONCLUSION:Our intensity correction method customized for multi-animal abdominal MR imaging using a 3T clinical scanner and dedicated multi-array coil could facilitate image interpretation.
    背景与目标: 目的:在单个会话中对多个小动物进行同步磁共振(MR)成像,可提高临床前成像实验的通量。使用带有多阵列线圈的3-tesla临床扫描仪进行的这种成像需要校正由线圈不均匀的灵敏度曲线引起的强度变化。我们探索了一种针对多动物MR成像(尤其是腹部成像)定制的校正强度的方法。
    方法:我们的动物实验机构委员会批准了该协议。我们使用3T临床扫描仪和定制的多阵列线圈同时获取了4个大鼠腹部的高分辨率T 1-,T 2-和T 2 *加权图像以及低分辨率质子密度加权图像(PDWI)。为了进行比较,我们还在4个单独的实验中在同一只大鼠中获得了T 1-,T 2-和T 2 *加权的体积线圈图像。我们使用内部创建的软件来校正强度变化。我们对PDWI应用阈值处理,以生成仅显示信号产生区域的二进制图像,通过将低通滤波后的PDWI除以低通滤波后的二进制图像逐像素计算出多阵列线圈灵敏度图,并除以未校正的T₁-,通过那些图的T 2或T 2 *加权图像以获得强度校正的图像。我们比较了强度校正的多阵列线圈图像和体积线圈图像之间的肝脏,脊椎管和肌肉之间的组织对比度。
    结果:我们的强度校正方法在研究的所有脉冲序列上均表现良好,并且在不降低动物实验通量的情况下校正了原始多阵列线圈图像中的变化。在强度校正的多阵列线圈图像和体积线圈图像之间,组织对比是可比的。
    结论:我们针对3D临床扫描仪和专用多阵列线圈为多动物腹部MR成像量身定制的强度校正方法可以促进图像解释。
  • 【膜环境中线圈β-折叠转变的热力学。】 复制标题 收藏 收藏
    DOI:10.1016/j.jmb.2007.02.082 复制DOI
    作者列表:Meier M,Seelig J
    BACKGROUND & AIMS: :Biologically important peptides such as the Alzheimer peptide Abeta(1-40) display a reversible random coil <==>beta-structure transition at anionic membrane surfaces. In contrast to the well-studied random coil left arrow over right arrow alpha-helix transition of amphipathic peptides, there is a dearth on information on the thermodynamic and kinetic parameters of the random coil left arrow over right arrow beta-structure transition. Here, we present a new method to quantitatively analyze the thermodynamic parameters of the membrane-induced beta-structure formation. We have used the model peptide (KIGAKI)(3) and eight analogues in which two adjacent amino acids were substituted by their d-enantiomers. The positions of the d,d pairs were shifted systematically along the three identical segments of the peptide chain. The beta-structure content of the peptides was measured in solution and when bound to anionic lipid membranes with circular dichroism spectroscopy. The thermodynamic binding parameters were determined with isothermal titration calorimetry and the binding isotherms were analysed by combining a surface partition equilibrium with the Gouy-Chapman theory. The thermodynamic parameters were found to be linearly correlated with the extent of beta-structure formation. beta-Structure formation at the membrane surface is characterized by an enthalpy change of DeltaH(beta)=-0.23 kcal/mol per residue, an entropy change of DeltaS(beta)=-0.24 cal/mol K residue and a free energy change of DeltaG(beta)=-0.15 kcal/mol residue. An increase in temperature induces an unfolding of beta-structure. The residual free energy of membrane-induced beta-structure formation is close to that of membrane-induced alpha-helix formation.
    背景与目标: :生物学上重要的肽,例如阿尔茨海默氏症肽Abeta(1-40)在阴离子膜表面显示出可逆的无规卷曲β结构。与经过充分研究的两亲性肽的右箭头α-螺旋过渡上的左旋箭头相反,缺少关于右箭头β-结构过渡上的随机螺旋左箭头的热力学和动力学参数的信息。在这里,我们提出了一种定量分析膜诱导的β-结构形成的热力学参数的新方法。我们使用了模型肽(KIGAKI)(3)和八个类似物,其中两个相邻的氨基酸被其d对映异构体取代。 d,d对的位置沿着肽链的三个相同部分系统地移动。肽的β结构含量在溶液中以及通过圆二色谱法与阴离子脂质膜结合后进行测量。用等温滴定热法测定热力学结合参数,并通过结合表面分配平衡与Gouy-Chapman理论分析结合等温线。发现热力学参数与β结构形成的程度线性相关。在膜表面形成β结构的特征是每个残基的DeltaHβ= -0.23 kcal / mol的焓变,DeltaSβ= -0.24 cal / mol K残基的熵变和ΔGβ= -0.15kcal / mol残余物。温度升高引起β结构的展开。膜诱导的β-结构形成的剩余自由能接近膜诱导的α-螺旋形成的剩余自由能。
  • 【经颅磁刺激和线圈放置的挑战:传统和立体定向神经导航策略的比较。】 复制标题 收藏 收藏
    DOI:10.1002/hbm.20360 复制DOI
    作者列表:Sparing R,Buelte D,Meister IG,Paus T,Fink GR
    BACKGROUND & AIMS: :The combination of transcranial magnetic stimulation (TMS) with functional neuroimaging has expanded the potential of TMS for human brain mapping. The precise and reliable positioning of the TMS coil is not a simple task, however. Modern frameless stereotaxic systems allow investigators to base navigation either on the subject's structural magnetic resonance imaging (MRI), functional MRI data, or the use of functional neuroimaging data from the literature, so-called "probabilistic approach." The latter assumes consistency across individuals in the location of task-related "activations" in standardized stereotaxic space. Conventional nonstereotaxic localization of brain areas is also a common method for defining the coil position. Our aim was to evaluate the accuracy of five different localization strategies in one single study. The left primary motor cortex (left M1-Hand) was used as target region. Three approaches were based on real-time frameless stereotaxy using information based on either anatomical or functional MRI. The remaining two strategies relied either on standard cranial landmarks (i.e., the International 10-20 EEG system) or a standardized function-guided procedure (i.e., the spatial relationship between the left and right M1-Hand). The results were compared to a TMS-based mapping of the primary motor cortex; center of gravity of motor-evoked potentials (MEP-CoG) was calculated for each subject (n = 10). Our findings suggest that highest precision can be achieved with fMRI-guided stimulation, which was accurate within the range of millimeters. Very consistent results were also obtained with the "probabilistic" approach. In view of these findings, we discuss the methods and special characteristics of each localization strategy.
    背景与目标: :经颅磁刺激(TMS)与功能性神经影像学的结合扩大了TMS在人脑测绘中的潜力。然而,TMS线圈的精确和可靠定位并不是一件容易的事。现代无框立体定位系统使研究人员可以根据受试者的结构磁共振成像(MRI),功能性MRI数据或使用文献中的功能性神经成像数据来进行导航,即所谓的“概率方法”。后者假设个人在标准化立体定位空间中与任务相关的“激活”的位置上具有一致性。大脑区域的常规非立体定位也是确定线圈位置的常用方法。我们的目的是在一项研究中评估五种不同定位策略的准确性。左初级运动皮层(左M1-Hand)用作目标区域。三种方法基于实时无框架立体定位,并使用基于解剖或功能MRI的信息。其余两种策略要么依靠标准的颅骨标志(即国际10-20 EEG系统),要么依靠标准化的功能指导程序(即左右M1-Hand之间的空间关系)。将结果与主运动皮层的基于TMS的映射进行比较;计算每个受试者(n = 10)的运动诱发电位(MEP-CoG)的重心。我们的发现表明,在fMRI指导的刺激下可以达到最高的精确度,该精确度在毫米范围内。使用“概率”方法也获得了非常一致的结果。鉴于这些发现,我们讨论了每种本地化策略的方法和特殊特征。
  • 【使用混合决策支持系统预测囊状颅内动脉瘤治疗的线圈栓塞后的形状直径。】 复制标题 收藏 收藏
    DOI:10.1007/s13246-013-0193-1 复制DOI
    作者列表:Owasirikul W,Tantivatana J,Gansawat D,Auethavekiat S
    BACKGROUND & AIMS: :The purpose of the study was to design a hybrid decision support system (HDSS) that could simulate the embolized coil selection pattern of the radiologists in aneurysms treatment. As the longest available length of the coils should be used in most cases, therefore only the shape diameter (SD) selection was modeled and varied. Ninety-eight aneurysms successfully treated by a radiologist with coil embolization were divided into two groups (86 for training and 12 randomly selected for validating). Eight aneurysms treated by another radiologist were also used to cross validate the proposed HDSS. The HDSS was developed using the classification and the linear regression methods (LRM). The dome and the width of an aneurysm were used as the system inputs. The system outputs were the SDs of the first three coils indexed according to the insertion order. The HDSS that consisted of Bagging classification and LRM achieved the highest accuracy for all cases. The errors were within 1 mm for the SD selection of the first two coils. For the third coil, the SD selection within 1 mm bound had 80 % accuracy. The experimental results indicated the feasibility of using the HDSS as the guidance for selecting the SDs of the first two coils. The selection of the third coil required more training data for the rarely used SD. Moreover, the cross validation with another radiologist showed the feasibility of using the proposed HDSS as the guidance, however further validation with more data is recommended.
    背景与目标: :该研究的目的是设计一种混合决策支持系统(HDSS),该系统可以模拟在动脉瘤治疗中放射科医生的栓塞线圈选择模式。由于在大多数情况下应使用线圈的最长可用长度,因此仅对形状直径(SD)选择进行建模和更改。由放射科医生成功完成线圈栓塞治疗的98个动脉瘤分为两组(用于训练的86个患者和用于验证的12个随机选择的患者)。由另一位放射科医师治疗的8个动脉瘤也被用来交叉验证所提议的HDSS。 HDSS是使用分类和线性回归方法(LRM)开发的。圆顶和动脉瘤的宽度用作系统输入。系统输出是根据插入顺序索引的前三个线圈的SD。由装袋分类和LRM组成的HDSS在所有情况下均达到了最高的准确性。前两个线圈的SD选择误差在1mm以内。对于第三个线圈,在1mm范围内的SD选择具有80%的精度。实验结果表明,将HDSS用作选择前两个线圈的SD的指导是可行的。对于很少使用的SD,选择第三个线圈需要更多的训练数据。此外,与另一位放射科医生的交叉验证显示了使用建议的HDSS作为指导的可行性,但是建议使用更多数据进行进一步验证。
  • 【原位大隐静脉旁路术中动静脉瘘的线圈栓塞术:成功率和并发症。】 复制标题 收藏 收藏
    影响因子 :
    发表时间:2007-06-01
    来源期刊:Rofo
    DOI:10.1055/s-2007-962922 复制DOI
    作者列表:Krüger K,Wagner D,Gawenda M,Strohe D,Uedelhoven J,Brunkwall J,Lackner K
    BACKGROUND & AIMS: PURPOSE:To determine the success and complication rate of coil embolization of arteriovenous fistulae on in situ saphenous vein bypasses. MATERIALS AND METHOD:82 AV-fistulae on 30 bypasses (28 patients, 20 men, age 62.5 +/- 8.3 years) were treated using coils. The success rate, complications, duration, amount of contrast material and radiation exposure were measured. Color-coded duplex sonography was performed 1 - 2 days and up to 6 - 18 months after embolization. RESULTS:The success rate was 68.3 %. The reasons for persistent fistula perfusion were: 96 % fistula not accessible, 4 % reperfusion during thrombolysis. 7 complications were observed in 6 bypasses: failure of placement and retrieving of coil (n = 4), thrombembolic complications with thrombolysis (n = 3). The duration of intervention was 118.3 +/- 46.6 min, the contrast material need was 277.03 +/- 94.0 ml, and the radiation exposure was 10 966 +/- 11 295 cGy/cm (2). Additional balloon dilatation was performed in 30 % of the bypasses. All bypasses were open 1-2 days after intervention. During follow-up, 11 persistent fistulae were detected. CONCLUSIONS:Coil-embolization of arteriovenous fistulae on saphena magna bypasses proved to be a method with moderate success and complication rates.
    背景与目标: 目的:确定原位大隐静脉旁路手术中动静脉瘘的线圈栓塞术的成功率和并发症发生率。
    材料与方法:使用线圈治疗了30例旁路手术中的82例AV瘘管(28例患者,20例男性,年龄62.5 /-8.3岁)。测量成功率,并发症,持续时间,造影剂用量和放射线照射。栓塞后1至2天以及最长6至18个月进行彩色编码的双工超声检查。
    结果:成功率为68.3%。持续性瘘管灌注的原因有:96%的瘘管无法通畅,溶栓期间4%的再灌注。在6次旁路中观察到7处并发症:放置和取回线圈失败(n = 4),血栓栓塞并发症并溶栓(n = 3)。干预时间为118.3 /-46.6分钟,造影剂需求为277.03 /-94.0 ml,放射线暴露为10 966 /-11 295 cGy / cm(2)。在30%的旁路中进行额外的球囊扩张。干预后1-2天,所有旁路均打开。在随访期间,发现了11例持续性瘘管。
    结论:在巨大隐静脉旁路上动静脉瘘的栓塞术是一种具有中等成功率和并发症发生率的方法。

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