Studies of copper(II) binding to glycylglycyl-L-tyrosine-N-methyl amide, a peptide mimicking the NH2-terminal copper(II)-binding site of dog serum albumin by analytical potentiometry, spectrophotometry, CD, and NMR spectroscopy

Unlike human serum albumin (HSA), dog serum albumin (DSA) does not possess the characteristics of the specific first binding site for Cu(II). In DSA, the important histidine residue in the third position, responsible for the Cu(II)-binding specificity in HSA, is replaced by a tyrosine residue. In order to study the influence of the tyrosine residue in the third position of DSA, a simple model of the NH2-terminal native sequence tripeptide of DSA, glycylglycyl-L-tyrosine-N-methylamide (GGTNMA) was synthesized and its Cu(II)-binding properties studied by analytical potentiometry, spectrophotometry, CD, and NMR spectroscopy. The species analysis indicated the existence of five mono-complexes at different protonation states: MHA, MA, MH-1A, MH-2A, MH-3A, and only one bis-complex MH-2A-2. The complexing ability of GGTNMA to Cu(II) was found to be weaker than that of the Cu(II) binding peptide models of HSA. The visible absorption spectra of Cu(II)-GGTNMA complexes are similar to those observed in the case of DSA-Cu(II) complexes. The weaker binding and the spectral properties of Cu(II)-GGTNMA complexes are consistent with less specific Cu(II)-binding properties of the peptide of this sequence similar to what was noted with DSA. CD results are in excellent agreement with species analysis and visible spectra where it is clearly evident that Cu(II) binds to GGTNMA starting from the alpha-NH2 group and step by step to deprotonated amide nitrogens as the pH is raised. The absence of any charge transfer band around 400 nm strongly indicates that Cu(II) does not bind to the phenolate group. Furthermore, NMR results are consistent with the noninvolvement of the tyrosine residue of GGTNMA in Cu(II) complexation. Thus, it is clear that the low Cu(II)-binding affinity of DSA is due to the genetic substitution of tyrosine for histidine at the NH2-terminal region of the protein.     

介入治疗成人非创伤性股骨头缺血性坏死的疗效分析

目的：分析介入治疗对于成人非创伤性股骨头缺血性坏死的疗效。方法：采用介入方法治疗95例共117髋非创伤性股骨头缺血性坏死。对比介入治疗前后DSA造影分型结果及血供异常例数。结果：117患髋中,Ia型的31病髋中,11髋（35．48％）介入治疗后动脉主干再通;Ib型的27髋中,24髋（88．89％）介入治疗后分支再通;II型的11髋中,5髋（45．45％）实质期股骨头缺损面积缩小;III型的10髋中,8髋（80．00％）静脉期见股骨头浓密染色明显减轻;Ⅳ型的33髋中,28髋（84．85％）可见动脉主干再通、分支增粗、实质期股骨头缺损面积缩小和静脉期股骨头染色减轻等。治疗前117病髋异常率为95．73％。经过介入治疗后,异常率为30．77％。治疗后异常率明显低于治疗前异常率（P〈0．01）。结论：介入治疗可有效改善非创伤性股骨头缺血性坏死血供异常,增加股骨头血供,具有操作简单、创伤小、疗效确切等优点。关键阗：股骨头缺血性坏死;介入治疗;数字减影血管造影     

4,4-Dimethyl-4-silapentane-1-ammonium trifluoroacetate (DSA), a promising universal internal standard for NMR-based metabolic profiling studies of biofluids, including blood plasma and serum

Nuclear magnetic resonance (NMR)-based metabolic profiling of biofluids and tissues are of key interest to enhance biomarker discovery for disease, drug efficacy and toxicity studies. Urine and blood plasma/serum are the biofluids of most interest as they are the most accessible in both clinical and preclinical studies. However, proteinaceous fluids, such as blood serum or plasma, represent the greatest technical challenge since the chemical shift (δ) and line-width (ν_1/2) of internal standards currently used for aqueous NMR samples are greatly affected by protein binding. We have therefore investigated the suitability of 4,4-dimethyl-4-silapentane-1-ammonium trifluoroacetate (DSA) as a universal internal standard for biofluids. Proton (¹H) NMR spectroscopy was used to determine the effect of serum pH (3, 7.4 and 10) and DSA concentration on the overall lineshape and position of the trimethylsilyl resonance of DSA. The results were compared to that of 3-(trimethylsilyl)propionic acid sodium salt (TSP). Both the chemical shift and line-width of the DSA peak were not significantly affected by pH or DSA concentration, whereas these parameters for TSP showed large variations due to protein binding. Furthermore, the peak area of DSA correlated linearly with its concentration under all pH conditions, whilst no linear correlation was observed with TSP. Overall, in contrast to TSP, these results support the use of DSA as an accurate universal internal chemical shift reference and concentration/normalisation standard for biofluids. In the case of proteinaceous biofluids such as serum, where no current standard is available, this offers a considerable saving in both operator and spectrometer time.     

Morphometry and hemodynamics of posterior communicating artery aneurysms: Ruptured versus unruptured

Posterior communicating artery (PCoA) aneurysms frequently rupture in small size (<7 mm). The aim of the study is to demonstrate morphometric and hemodynamic analyses in ruptured and unruptured PCoA aneurysms to improve predictive accuracy for rupture. Geometrical models were reconstructed from rotational DSA images of 57 ruptured and 22 unruptured side-wall PCoA aneurysms, which were classified into four two-dimensional (2D) groups by a combination of H/D and H/S ratios (H: dome height, D: dome diameter, and S: semi-axis height). Surface area ratio (SAR) of low time-averaged wall shear stress (TAWSS, ≤4 dynes cm⁻²) and high oscillatory shear index (OSI, ≥0.15) were computed in aneurysms. We hypothesized that a two-step analysis method, i.e., one-dimensionally morphometric and hemodynamic analyses in each 2D group, can enhance accuracy of PCoA aneurysm rupture evaluation. There was the highest incidence of H/D > 1 and H/S ≤ 2 with the largest surface area and SAR-TAWSS, but the lowest incidence of H/D ≤ 1 and H/S > 2 with the smallest surface area and SAR-TAWSS in ruptured PCoA aneurysms. PCoA aneurysms of H/D > 1 and H/S ≤ 2 with surface area > 70 mm², H/D ≤ 1 and H/S > 2 with neck diameter > 2.3 mm, H/D ≤ 1 and H/S ≤ 2 with aneurysmal height/parent diameter ratio > 1.0, and H/D > 1 and H/S > 2 with aneurysmal angle > 115° need special attention for clinical diagnosis and treatment. The study highlighted the importance of the two-step analysis method for clinical evaluation of PCoA aneurysm rupture.     

Nickel(II) binding to glycylglycyl-L-tyrosine-N-methyl amide, a peptide mimicking the NH2-terminal nickel(II)-binding site of dog serum albumin: a 1H- and 13C-nuclear magnetic resonance investigation

The nonspecificity of dog serum albumin (DSA) for Ni(II) is mimicked by the simplest tripeptide, glycylglycyl-L-tyrosine-N-methyl amide, which forms a planar complex at high pH. In this study, the 1H and 13C nuclear magnetic resonance (nmr) spectra of the free and complexed peptide are reported. As the pH is increased for the free peptide, the deprotonation of the terminal amino group (pKa = 7.94) is reflected most strongly by the chemical shift changes of the NH2-terminal -CH2CO- unit. Large upfield and downfield shifts for the tyrosine C xi, C epsilon and C gamma carbon resonances occur on the ionization of the phenolic hydroxyl group. The planar Ni(II) complex is in slow exchange on the nmr time scale and is of 1:1 stoichiometry. The greater chemical shift changes on Ni(II) coordination are observed from the protons nearest the peptide and amino nitrogens:amide CH3 (-0.704), Tyr(3) alpha-CH (-0.667), Gly(1) alpha-CH2 (-0.382), and Gly(2) alpha-CH2 (-0.519, -0.487). In the 13C spectrum, the Gly(1) C alpha (+7.58) is most affected. The Ni(II) ion is therefore at the center of four coordinating nitrogens. Changes in the coupling constants for the Tyr(3) -CH-CH2- moiety suggests a mainly gauche conformation with the tyrosyl ring positioned above the plane of coordination and a weak bonding interaction with the Ni(II) ion is indicated. These results provide structural information regarding the reduced affinity of DSA for Ni(II).     

DSA affinity glycoproteome of human liver tissue

Due to the critical roles of glycoproteins in the activities of cells to tissues, mapping of liver glycoproteome may provide valuable basic information for finding disease marker proteins. In this study, Datura Stramonium Agglutinin (DSA) was chosen to enrich N-linked glycoproteins for its broader specificity with tri- or tetra-antennary complex type. DSA affinity glycoproteins’ profiles of human liver tissue were generated by two-dimensional electrophoresis (2-DE) followed by glycoprotein staining based on multiplexed proteomics (MP) technology. 64 ± 3 (n = 3) protein spots were detected and 41 of glycoproteins were identified via peptide mass fingerprinting (PMF) using MALDI-TOF-MS/MS and annotated to IPI databases. Identified glycoproteins definitely take part in the regulation of cell cycle and metabolic processes. The detailed carbohydrate moiety of some glycoproteins might be concluded according to the literatures. The construction of DSA affinity glycoprotein database would contribute to the subsequent research.     

Electron spin resonance study of the copper(II) complexes of human and dog serum albumins and some peptide analogs

Electron spin resonance spectra of the first Cu(II) complexes of human serum albumin, dog serum albumin, l-aspartyl-l-histidine N-methylamide and glycyl-glycyl-l-histidine N-methylamide have been studied using isotopically pure ⁶⁵Cu in its chloride form. At 77° K, the esr spectra of Cu(II) complex of human serum albumin exhibited only one form of esr signal between pH 6.5 and 11. No intermediate forms were detected. The presence of an equally spaced nine-line superhyperfine structure with spacing ～15 G indicated considerable covalent bonding between Cu(II) and four nitrogen atoms derived from the protein. The esr spectrum form of Cu(II) bound to human serum albumin detected at neutral pH would be consistent with the participation of four nitrogens from the α-NH₂ group, two peptide groups, and the imidazole group of a histidine residue. In contrast, the esr spectra of Cu(II)-dog serum albumin complex showed a transition from a low pH form to a high pH form as the pH was increased to 9.5. These spectral changes were found to be reversible upon lowering the pH. Ligand superhyperfine splittings in the low pH form of the esr signal of Cu(II)-dog albumin were not resolved. The distinct pH dependence of the esr signals observed in human and dog serum albumin complexes could be correlated to their respective optical spectra changes as a function of pH. At room temperature and in the pH range between 6 and 11, the esr spectra of Cu(II) complexes of l-aspartyl-l-alanyl-l-histidine N-methylamide and glycyl-glycyl-l-histidine N-methylamide exhibited a well-resolved nine-line superhyperfine structure indicating metal coordination with four equivalent nitrogen atoms of peptide.     

影像诊断在颅内动脉瘤中的研究进展

颅内动脉瘤(intracranial aneurysms,ICA)是由于脑血管局部异常改变而产生的血管瘤样突起,世界2%的人口患有颅内动脉瘤。颅内动脉瘤是引起脑卒中的第三大病因,仅次于脑血栓形成和高血压脑出血,脑卒中病死率、致残率极高,总病死率约为40~50%,早期诊断ICA对预防脑卒中意义重大。颅内动脉瘤的早期诊断主要依赖于影像学检查,近年多层螺旋CT、MRI及DSA技术的迅猛发展对颅内动脉瘤的早期诊断有很大帮助,本文就CT以及MRI功能成像在颅内动脉瘤的应用研究进展进行综述。     

盆腔疾病髂内动脉栓塞术的研究进展

髂内动脉栓塞是盆腔出血性疾病和肿瘤治疗的重要治疗方法,常规采用Seldinger技术,从一侧股动脉径路两侧髂内动脉选择性与超选择性插管。髂内动脉是盆腔脏器主要供血来源,根据数字减影动脉造影术（Digital subtraction arteriography,DSA）功能可分为：常规DSA,旋转DSA,平板数字减影旋转血管造影与三维血管重建和路图技术。栓塞剂可分为颗粒型和液态型栓塞剂。本文综述了盆腔疾病髂内动脉栓塞术近年来的研究进展。     

冠状动脉CTA和DSA对冠心病患者的临床诊断价值比较

目的:比较冠状动脉CT血管成像(CT angiography,CTA)以及数字减影血管造影(digital subtraction angiography,DSA)诊断冠心病的临床价值差异。方法:选择2013年12月至2020年3月安徽医科大学第三附属医院、安徽医科大学第四附属医院收治的60例冠心病患者为研究对象,首先对其实施多排螺旋CT冠状动脉血管造影检测(CTA),而后2 w内再对其实施DSA检测,比较两种检测方式对不同血管狭窄程度、不同性质斑块检出率的差异,最后以DSA检测结果为金标准,评估CTA对冠状动脉狭窄诊断的一致性、灵敏度、特异度、阳性预测值和阴性预测值。结果:(1)CTA检测狭窄血管共计387支,轻度狭窄152支(39.28%),中度狭窄118支(30.49%),重度狭窄105支(27.13%),闭塞12支(3.10%);DSA检测狭窄血管392支,轻度狭窄150支(38.27%),中度狭窄124支(31.63%),重度狭窄112支(28.57%),闭塞6支(1.53%),两组各血管狭窄类型比较差异无统计学意义(P0.05);(2)CTA检测斑块69个,其中钙化斑43个(62.32%),非钙化斑26个(37.68%),DSA检测斑块61个,其中钙化斑33个(54.10%),非钙化斑28个(45.50%),两种检测方式差异无统计学意义(P0.05);(3)以DSA检测为金标准,CTA对重度及以上血管狭窄诊断一致性为99.23%,特异度为98.31%,灵敏度为99.64%,阳性预测值为99.15%,阴性预测值为99.27%。结论:与DSA相比,CTA对冠心病患者血管狭窄的诊断价值相当,且属于无创检测,在冠心病早期筛查中临床应用价值更高。