Spectral K-edge subtraction imaging of experimental non-radioactive barium uptake in bone

PurposeTo evaluate the feasibility of using non-radioactive barium as a bone tracer for detection with synchrotron spectral K-edge subtraction (SKES) technique.MethodsMale rats of 1-month old (i.e., developing skeleton) and 8-month old (i.e., skeletally mature) were orally dosed with low dose of barium chloride (33 mg/kg/day Ba²⁺) for 4 weeks. The fore and hind limbs were dissected for imaging in projection and computed tomography modes at 100 μm and 52 μm pixel sizes. The SKES method utilizes a single bent Laue monochromator to prepare a 550 eV energy spectrum to encompass the K-edge of barium (37.441 keV), for collecting both ‘above’ and ‘below’ the K-edge data sets in a single scan.ResultsThe SKES has a very good focal size, thus limits the ‘crossover’ and motion artifacts. In juvenile rats, barium was mostly incorporated in the areas of high bone turnover such as at the growth plate and the trabecular surfaces, but also in the cortical bone as the animals were growing at the time of tracer administration. However, the adults incorporated approximately half the concentration and mainly in the areas where bone remodeling was predominant and occasionally in the periosteal and endosteal layers of the diaphyseal cortical bone.ConclusionsThe presented methodology is simple to implement and provides both structural and functional information, after labeling with barium, on bone micro-architecture and thus has great potential for in vivo imaging of pre-clinical animal models of musculoskeletal diseases to better understand their mechanisms and to evaluate the efficacy of pharmaceuticals.     

Complete microscale profiling of tumor microangiogenesis: A microradiological methodology reveals fundamental aspects of tumor angiogenesis and yields an array of quantitative parameters for its characterization

Complete profiling would substantially facilitate the fundamental understanding of tumor angiogenesis and of possible anti-angiogenesis cancer treatments. We developed an integrated synchrotron-based methodology with excellent performances: detection of very small vessels by high spatial resolution (~ 1 μm) and nanoparticle contrast enhancement, in vivo dynamics investigations with high temporal resolution (~ 1 ms), and three-dimensional quantitative morphology parametrization by computer tracing. The smallest (3–10 μm) microvessels were found to constitute > 80% of the tumor vasculature and exhibit many structural anomalies. Practical applications are presented, including vessel microanalysis in xenografted tumors, monitoring the effects of anti-angiogenetic agents and in vivo detection of tumor vascular rheological properties.     

When identical functional groups are not identical: A DFT study of the effects of molecular environment on sulfur K-edge X-ray absorption spectra

Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have been used to elucidate differences in the sulfur K-edge spectra of three pairs of related compounds: methionine and , cystine and (±)6-thioctic amide, and (Me)₂SO₃ and (CH₂)₂SO₃. TD-DFT is shown to accurately reproduce all the experimental XAS spectra. The 2 eV energy difference in the sulfur K-edge rising edge position between methionine and trimethylsulfonium is shown to derive from changes in bonding rather than the increase in effective nuclear charge. A similar insensitivity to effective nuclear charge is found in the XAS spectra of cystine and (±)6-thioctic amide. These surprising results are traced back to the fact that XAS spectra reflect orbital energy differences, rather than a measure of the atomic potential. The change in atomic potential following oxidation or reduction affects the core and valence orbitals almost equally. In all cases DFT calculations showed that the dramatic differences in sulfur K-edge spectra found between functional groups in alternative molecular environments derive from the variations in orbital mixing and energies following from bonding. However, XAS rising-edge energy positions have a near linear correlation with oxidation state. This is attributed to the fact that bond strength typically increases with oxidation state. Therefore, although XAS rising-edge energies are an approximate measure of the oxidation state of the absorbing atom, it is important to recognize that the correlation of XAS edge energy with effective nuclear charge is not direct. This result is finally applied to the question of quantitative sulfur speciation in complex materials of chemical, biological, or geological origin.     

大黄联合抗生素治疗脑出血合并肺部感染的临床疗效观察

目的：观察大黄联合抗生素治疗脑出血后肺部感染的临床疗效。方法：96例急性高血压脑出血血肿清除术后并发肺部感染患者随机分为治疗组（56例）和对照组（40例）。对照组应用抗生素治疗,治疗组在抗生素治疗的基础上加用大黄6g,以温开水100mL调匀后经胃管鼻饲,每日2次,共治疗7天。治疗结束后比较和评价两组的治疗效果效果。结果：治疗组患者肺哆音消失的时间、炎症消散的时间和平均治愈天数分别为3．52±1．81、10．32±3．25、10．73±3．26天,较对照组（分别为10．86±3．43、13．51±2．66、14．73±3．11）均显著缩短,差异有显著统计学意义（P〈0．01）。治疗组和对照组治疗总有效率分别为94．64％和85％,差异有统计学意义（P〈0．05）。两组不良反应的发生率比较无统计学差异（P〉0．05）。结论：大黄联合抗生素治疗脑出血术后合并肺部感染,可缩短治疗时间,提高疗效,且无严重不良反应。     

VCTDSA联合CT灌注成像在急性缺血性卒中诊断运用探究

目的：探讨64层容积CT数字减影血管造影（Volume computed tomography digital subtraction angiography, VCTDSA）联合CT灌注成像在急性缺血性卒中诊断价值。方法：回顾性分析45例临床确诊为急性缺血性卒中患者的临床资料,分别给予VCTDSA与CT灌注成像处理,分析这两种技术对急性缺血性卒中患者的诊断敏感性和特异性。结果：45例患者检查有颅内有不同部位出血灶,多见于脑室,均伴有不同程度的异常血管网形成,其中VCTDSA图像质量优于CT灌注成像,VCTDSA较DSA可准确显示和测量动静脉瘘口大小,VCTDSA与MRA在瘤体长轴、瘤颈的比较中无显著性差异。结论：与其他减影CTA比较,VCTDSA联合CT灌注成像在急性缺血性卒中患者的诊断中具有优势。     

Chloride ligation in inorganic manganese model compounds relevant to Photosystem II studied using X-ray absorption spectroscopy

Chloride ions are essential for proper function of the photosynthetic oxygen-evolving complex (OEC) of Photosystem II (PS II). Although proposed to be directly ligated to the Mn cluster of the OEC, the specific structural and mechanistic roles of chloride remain unresolved. This study utilizes X-ray absorption spectroscopy (XAS) to characterize the Mn–Cl interaction in inorganic compounds that contain structural motifs similar to those proposed for the OEC. Three sets of model compounds are examined; they possess core structures Mn^IV₃O₄X (X=Cl, F, or OH) that contain a di--oxo and two mono--oxo bridges or Mn^IV₂O₂X (X=Cl, F, OH, OAc) that contain a di--oxo bridge. Each set of compounds is examined for changes in the XAS spectra that are attributable to the replacement of a terminal OH or F ligand, or bridging OAc ligand, by a terminal Cl ligand. The X-ray absorption near edge structure (XANES) shows changes in the spectra on replacement of OH, OAc, or F by Cl ligands that are indicative of the overall charge of the metal atom and are consistent with the electronegativity of the ligand atom. Fourier transforms (FTs) of the extended X-ray absorption fine structure (EXAFS) spectra reveal a feature that is present only in compounds where chloride is directly ligated to Mn. These FT features were simulated using various calculated Mn–X interactions (X=O, N, Cl, F), and the best fits were found when a Mn–Cl interaction at a 2.2–2.3 Å bond distance was included. There are very few high-valent Mn halide complexes that have been synthesized, and it is important to make such a comparative study of the XANES and EXAFS spectra because they have the potential for providing information about the possible presence or absence of halide ligation to the Mn cluster in PS II.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00775-003-0520-1Abbreviations bpea N,N-bis(2-pyridylmethyl)ethylamine - EXAFS extended X-ray absorption fine structure - FT Fourier transform - IPE inflection point energy - OEC oxygen evolving complex - PS II Photosystem II - tacn 1,4,7-triazacyclononane - XANES X-ray absorption near edge structure - XAS X-ray absorption spectroscopy - XRD X-ray diffraction     

烟雾病5例临床分析

目的：研究烟雾病（moyamoya disease,MMD）的临床及影像学特征。方法：回顾性分析5例烟雾病患者,分析其临床及影像学特点。结果：本组病例既往均无阳性病史,中、青年起病,男性居多,均以缺血性脑血管病起病,肢体瘫痪不重,经颅多普勒（TCD）及头颅核磁改变明显,数字减影血管造影（DSA）检查均存在血管闭塞及侧支开放,烟雾血管网形成,1例MRA证实烟雾血管网形成。结论：对于无既往史的中、青年脑卒中患者,要考虑MMD的可能,需完善TCD、头核磁检寻找证据,最后完善数字减影血管造影确诊。     

烟雾病5 例临床分析

目的:研究烟雾病(moyamoya disease,MMD)的临床及影像学特征。方法:回顾性分析5例烟雾病患者,分析其临床及影像学特点。结果:本组病例既往均无阳性病史,中、青年起病,男性居多,均以缺血性脑血管病起病,肢体瘫痪不重,经颅多普勒(TCD)及头颅核磁改变明显,数字减影血管造影(DSA)检查均存在血管闭塞及侧支开放,烟雾血管网形成,1例MRA证实烟雾血管网形成。结论:对于无既往史的中、青年脑卒中患者,要考虑MMD的可能,需完善TCD、头核磁检寻找证据,最后完善数字减影血管造影确诊。     

BMIT facility at the Canadian Light Source: Advances in X-ray phase-sensitive imaging

The BioMedical Imaging and Therapy (BMIT) facility [1,2] located at the Canadian Light Source, provides synchrotron-specific imaging and radiation therapy capabilities. There are two separate beamlines used for experiments: the bending magnet (05B1-1) and the insertion device (05ID-2) beamline.The bending magnet beamline provides access to monochromatic beam spanning a spectral range of 15–40 keV, and the beam is 240 mm wide in the POE-2 experimental hutch. Users can also perform experiments with polychromatic (pink) beam.The insertion device beamline was officially opened for general user program in 2015. The source for the ID beamline is a multi-pole, superconducting 4.3 T wiggler. The high field gives a critical energy over 20 keV. The optics hutches prepare a beam that is 220 mm wide in the last experimental hutch SOE-1. The monochromatic spectral range spans 25–150+ keV. Several different X-ray detectors are available for both beamlines, with resolutions ranging from 2 μm to 200 μm.BMIT provides a number of imaging techniques including standard absorption X-ray imaging, K-edge subtraction imaging (KES), in-line phase contrast imaging (also known as propagation based imaging, PBI) and Diffraction Enhanced Imaging/Analyzer Based Imaging (DEI/ABI), all in either projection or CT mode. PBI and DEI/ABI are particularly important tools for BMIT users since these techniques enable visualization of soft tissue and allow for low dose imaging.     

同步辐射在显微CT中的应用

计算机X射线断层成像技术（CT）是利用X射线的穿透能力对物体进行扫描,所得信号经过反投影的算法而得到物体二维分布的一种成像方法,已经在医学诊断、工业探伤等领域广泛应用。但是由于实验室光源的低通量,光源点大小及其单色性等限制了其向高分辨发展,通常其分辨率在0．5mm左右。利用微焦点X射线源作为光源的显微CT分辨率可以达到微米量级,但是由于其光通量低且为非单色光,对不同样品有不同程度的束线硬化,影响了其真实分辨率。同步辐射作为一种新兴的光源有高亮度、高光子通量、高准直性、高极化性、高相干性及宽的频谱范围的特点,配合高分辨的X射线探测器,可以发展同步辐射显微CT,其分辨率可达10μm以下。利用同步辐射的高空间相干性开展位相衬度显微CT的研究,对低吸收物质也可以清晰三维成像。新建的上海光源的X射线成像及生物医学应用线站开展了三维显微CT方面的研究,经过初步试验,得到了较好的结果。     

Speciation of sulfur from filamentous microbial mats from sulfidic cave springs using X-ray absorption near-edge spectroscopy

Most transformations within the sulfur cycle are controlled by the biosphere, and deciphering the abiotic and biotic nature and turnover of sulfur is critical to understand the geochemical and ecological changes that have occurred throughout the Earth's history. Here, synchrotron radiation-based sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy is used to examine sulfur speciation in natural microbial mats from two aphotic (cave) settings. Habitat geochemistry, microbial community compositions, and sulfur isotope systematics were also evaluated. Microorganisms associated with sulfur metabolism dominated the mats, including members of the Epsilonproteobacteria and Gammaproteobacteria. These groups have not been examined previously by sulfur K-edge XANES. All of the mats consisted of elemental sulfur, with greater contributions of cyclo-octasulfur (S8) compared with polymeric sulfur (Smicro). While this could be a biological fingerprint for some bacteria, the signature may also indicate preferential oxidation of Smicro and S8 accumulation. Higher sulfate content correlated to less S8 in the presence of Epsilonproteobacteria. Sulfur isotope compositions confirmed that sulfur content and sulfur speciation may not correlate to microbial metabolic processes in natural samples, thereby complicating the interpretation of modern and ancient sulfur records.     

容积减影成像计算机自动化技术与实现

探讨在PC机上对容积CT灌注（CTP）源影像全自动生成减影CTP源影像的方法。首先在WindowsXP操作系统中使用Matlab,对4层螺旋CTP源影像进行DICOM文件格式解析,获得CT成像设备的球管每转一周扫描层数及容积减影方法需要的其它参数信息,然后经过容积的CT值集合读、容积的CT值集合减以及容积的CT值集合写等几个步骤,生成减影CTP源影像的DICOM文件序列。使用该容积减影方法得到的减影CTP源影像,在定性肉眼观察和定量CT值矩阵比对上,与使用CT影像工作站上的减影软件手工逐层半自动减影得到的结果类同。容积减影方法实现了容积CTP源影像的自动化减影处理与成像,为最终形成一个一站式的减影CTP软件奠定了基础。     

高分辨率磁共振成像对颅内动脉粥样硬化斑块的诊断价值

目的:探讨高分辨率核磁共振成像(magnetic resonance imaging,MRI)对颅内动脉粥样硬化斑块的诊断价值。方法:选择2016年1月至2018年6月在我院诊治的缺血性脑卒中患者134例作为研究对象,所有患者都给予数字减影血管造影(Digital subtraction angiography,DSA)与高分辨率MRI检查,记录颅内动脉粥样硬化斑块特征与分型,以DSA诊断为金标准,判断MRI的诊断价值(阳性预测值、特异度、灵敏度、阴性预测值)。结果:在134例患者中,高分辨率MRI显示未见斑块62例,Ⅰ型5例、Ⅱ型26例,Ⅲ型26例、Ⅳ型15例,与DSA诊结果一致124例,占比92.5%。高分辨率MRI与DSA诊断颅内动脉粥样硬化斑块的Kappa值为0.89,MRI对各分型的颅内动脉粥样硬化斑块的阳性预测值、特异度、灵敏度、阴性预测值分别为:Ⅰ型87.0%、99.2%、95.8%和99.2%,Ⅱ型81.0%、98.5%、83.4%和98.5%,Ⅲ型82.7%、82.7%、84.0%和95.7%,Ⅳ型100.0%、100.0%、100.0%和100.0%。结论:高分辨率MRI用于诊断颅内动脉粥样硬化斑块的价值与DSA检查有很好的一致性,可反映硬化斑块的分型。     

Sulfur oxidation activities of pure and mixed thermophiles and sulfur speciation in bioleaching of chalcopyrite

The sulfur oxidation activities of four pure thermophilic archaea Acidianus brierleyi (JCM 8954), Metallosphaera sedula (YN 23), Acidianus manzaensis (YN 25) and Sulfolobus metallicus (YN 24) and their mixture in bioleaching chalcopyrite were compared. Meanwhile, the relevant surface sulfur speciation of chalcopyrite leached with the mixed thermophilic archaea was investigated. The results showed that the mixed culture, with contributing significantly to the raising of leaching rate and accelerating the formation of leaching products, may have a higher sulfur oxidation activity than the pure cultures, and jarosite was the main passivation component hindering the dissolution of chalcopyrite, while elemental sulfur seemed to have no influence on the dissolution of chalcopyrite. In addition, the present results supported the former speculation, i.e., covellite might be converted from chalcocite during the leaching experiments, and the elemental sulfur may partially be the derivation of covellite and chalcocite.     

颅内静脉系统血栓形成6例临床分析

目的：探讨颅内静脉系统血栓形成（CVT）的临床表现、影像学特征以及治疗方法对临床诊断的意义。方法：回顾性分析首都医科大学宣武医院收治的6例CVT患者的临床表现及影像学特征与治疗方法。结果：6例临床表现无特殊,4例经MRI＋MRV确诊,3例DSA检查确诊,1例介入治疗,4例抗凝治疗,2例保守,无死亡患者。结论：静脉系统血栓形成临床症状缺乏特异性,临床遇到急性起病的头痛、呕吐,伴或不伴有局灶性神经功能缺损或癫痫发作、意识障碍的青中年人,应高度怀疑CVT。早期应用抗凝、溶栓等治疗方法,对改善预后具有较高的临床应用价值。     

颅内静脉系统血栓形成6 例临床分析

目的:探讨颅内静脉系统血栓形成(CVT)的临床表现、影像学特征以及治疗方法对临床诊断的意义。方法:回顾性分析首都医科大学宣武医院收治的6例CVT患者的临床表现及影像学特征与治疗方法。结果:6例临床表现无特殊,4例经MRI+MRV确诊,3例DSA检查确诊,1例介入治疗,4例抗凝治疗,2例保守,无死亡患者。结论:静脉系统血栓形成临床症状缺乏特异性,临床遇到急性起病的头痛、呕吐,伴或不伴有局灶性神经功能缺损或癫痫发作、意识障碍的青中年人,应高度怀疑CVT。早期应用抗凝、溶栓等治疗方法,对改善预后具有较高的临床应用价值。