Videodensitometric analysis of advanced carotid plaque: correlation with MMP-9 and TIMP-1 expression

Background: Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of MMP (TIMP) promote derangement of the extracellular matrix, which is ultimately reflected in plaque images seen on ultrasound. Videodensitometry can identify structural disturbances in plaques. Objectives: To establish the correlations between values determined using videodensitometry in B-mode ultrasound images of advanced carotid plaques and the total expression of MMP-9 and TIMP-1 in these removed plaques. Methods: Thirty patients underwent ultrasonic tissue characterization of carotid plaques before surgery, using mean gray level (MGL), energy, entropy and homogeneity. Each patient was assigned preoperatively to one of 2 groups: group I, symptomatic patients (n = 16; 12 males; mean age 66.7 +/- 6.8 years), and group II, asymptomatic patients (n = 14; 8 males; mean age 67.6 +/- 6.81 years). Tissue specimens were analyzed for MMP-9 and TIMP-1 expression. Nine carotid arteries were used as normal tissue controls. Results: MMP-9 expression levels were elevated in group II and in normal tissues compared to group I (p < 0.001). TIMP-1 levels were higher in group II than in group I, and significantly higher in normal tissues than in group I (p = 0.039). The MGL was higher in group II compared to group I (p = 0.038). Energy had greater values in group II compared to group I (p = 0.02). There were no differences between patient groups in homogeneity and entropy. Energy positively correlated with MMP-9 and TIMP-1 expression (p = 0.012 and p = 0.031 respectively). Homogeneity positively correlated with MMP-9 and TIMP-1 expression (p = 0.034 and p = 0.047 respectively). There were no correlations between protein expression and MGL or entropy. Conclusions: Videodensitometric computer analysis of ultrasound scanning images can be used to identify stable carotid plaques, which have higher total expression levels of MMP-9 and TIMP-1 than unstable plaques.

Differential expression of E-cadherin gene in human neuroepithelial tumors

Cadherins are cell-to-cell adhesion molecules that play an important role in the establishment of adherent-type junctions by mediating calcium-dependent cellular interactions. The CDH1 gene encodes the transmembrane glycoprotein E-cadherin which is important in maintaining homophilic cell-cell adhesion in epithelial tissues. E-cadherin interacts with catenin proteins to maintain tissue architecture. Structural defects or loss of expression of E-cadherin have been reported as a common feature in several human cancer types. This study aimed to evaluate the expression of E-cadherin and their correlation with clinical features in microdissected brain tumor samples from 81 patients, divided into 62 astrocytic tumors grades I to IV and 19 medulloblastomas, and from 5 white matter non-neoplasic brain tissue samples. E-cadherin (CDH1) gene expression was analyzed by quantitative real-time polymerase chain reaction. Mann-Whitney, Kruskal-Wallis, Kaplan-Meir, and log-rank tests were performed for statistical analyses. We observed a decrease in expression among pathological grades of neuroepithelial tumors. Non-neoplasic brain tissue showed a higher expression level of CDH1 gene than did neuroepithelial tumors. Expression of E-cadherin gene was higher in astrocytic than embryonal tumors (P = 0.0168). Low-grade malignancy astrocytomas (grades I-II) showed higher CDH1 expression than did high-grade malignancy astrocytomas (grades III-IV) and medulloblastomas (P < 0.0001). Non-neoplasic brain tissue showed a higher expression level of CDH1 gene than grade I malignancy astrocytomas, considered as benign tumors (P = 0.0473). These results suggest that a decrease in E-cadherin gene expression level in high-grade neuroepithelial tumors may be a hallmark of malignancy in dedifferentiated tumors and that it may be possibly correlated with their progression and dissemination.

Ultra-Structural Changes at the Apical Stop Irradiated with CO(2) Laser

Objective: This study evaluated ultra-structural dentine changes at the apical stop after CO(2) laser irradiation used during biomechanical preparation. Background: Most studies evaluating the sealing efficiency of CO(2) lasers have been carried out after apical root canal resections and retro-filling procedures. Methods: Sixty human canines were prepared with #1 to #6 Largo burs. The apical stops were established at 1 mm (n = 30) and 2 mm (n = 30) from the apex. Final irrigation was performed with 1% NaOCl and 15% EDTA followed by 20 ml of distilled and deionized water. Specimens were subdivided into three subgroups (n = 10 for each stop distance): GI-no radiation (n = 20); GII-3W potency (n = 20), GIII-5W potency (n = 20). After preparation, specimens were evaluated by scanning electron microscopy, with ultra-structural changes classified according to a scoring system based on six qualitatively different outcomes. Results: Statistical analysis using the Mann-Whitney test confirmed more intense results for the specimens irradiated at 5 W potency than at 3 W (p<0.0001). The Kruskal-Wallis test indicated that when using the same potencies (3 or 5 W) at 1 and 2 mm from the apex, there were no statistically significant differences in ultra-structural changes. Conclusions: Our results showed that ultra-structural changes ranged from smear layer removal to dentine fusion. As laser potency was increased from 3 to 5 W, ultra-structural changes included extensive fused lava-like areas sealing the apical foramen.

Production of the refolded oligopeptide-binding protein (OppA) encoded by the citrus pathogen Xanthomonas axonopodis pv. citri

The oligopeptide-binding protein, OppA, binds and ushers oligopeptide substrates to the membrane-associated oligopeptide permease (Opp), a multi-component ABC-type transporter involved in the uptake of oligopeptides expressed by several bacterial species. In the present study, we report the cloning, purification, refolding and conformational analysis of a recombinant OppA protein derived from Xanthomonas axonopodis pv. citri (X. citri), the etiological agent of citrus canker. The oppA gene was expressed in Escherichia coli BL21 (DE3) strain under optimized inducing conditions and the recombinant protein remained largely insoluble. Solubilization was achieved following refolding of the denatured protein. Circular dichroism analysis indicated that the recombinant OppA protein preserved conformational features of orthologs expressed by other bacterial species. The refolded recombinant OppA represents a useful tool for structural and functional analyses of the X. citri protein.

X-ray phase measurements as a probe of small structural changes in doped nonlinear optical crystals

X-ray multiple diffraction experiments with synchrotron radiation were carried out on pure and doped nonlinear optical crystals: NH(4)H(2)PO(4) and KH(2)PO(4) doped with Ni and Mn, respectively. Variations in the intensity profiles were observed from pure to doped samples, and these variations correlated with shifts in the structure factor phases, also known as triplet phases. This result demonstrates the potential of X-ray phase measurements to study doping in this type of single crystal. Different methodologies for probing structural changes were developed. Dynamical diffraction simulations and curve fitting procedures were also necessary for accurate phase determination. Structural changes causing the observed phase shifts are discussed.

Structural properties of buried conducting layers formed by very low energy ion implantation of gold into polymer

We have investigated the fundamental structural properties of conducting thin films formed by implanting gold ions into polymethylmethacrylate (PMMA) polymer at 49 eV using a repetitively pulsed cathodic arc plasma gun. Transmission electron microscopy images of these composites show that the implanted ions form gold clusters of diameter similar to 2-12 nm distributed throughout a shallow, buried layer of average thickness 7 nm, and small angle x-ray scattering (SAXS) reveals the structural properties of the PMMA-gold buried layer. The SAXS data have been interpreted using a theoretical model that accounts for peculiarities of disordered systems.

Depth-dependent local structures in thin films unraveled by grazing-incidence X-ray absorption spectroscopy

A method of using X-ray absorption spectroscopy together with resolved grazing-incidence geometry for depth profiling of atomic, electronic or chemical local structures in thin films is presented. The quantitative deconvolution of thickness-dependent spectral features is performed by fully considering both scattering and absorption formalisms. Surface oxidation and local structural depth profiles in nanometric FePt films are determined, exemplifying the application of the method.

Electronic, structural, and transport properties of Ni-doped graphene nanoribbons

We have investigated the electronic and transport properties of zigzag Ni-adsorbed graphene nanoribbons (Ni/GNRs) using ab initio calculations. We find that the Ni adatoms lying along the edge of zigzag GNRs represent the energetically most stable configuration, with an energy difference of approximately 0.3 eV when compared to the adsorption in the middle of the ribbon. The carbon atoms at the ribbon edges still present nonzero magnetic moments as in the pristine GNR even though there is a quenching by a factor of almost five in the value of the local magnetic moments at the C atoms bonded to the Ni. This quenching decays relatively fast and at approximately 9 A from the Ni adsorption site the magnetic moments have already values close to the pristine ribbon. At the opposite edge and at the central carbon atoms the changes in the magnetic moments are negligible. The energetic preference for the antiparallel alignment between the magnetization at the opposite edges of the ribbon is still maintained upon Ni adsorption. We find many Ni d-related states within an energy window of 1 eV above and below the Fermi energy, which gives rise to a spin-dependent charge transport. These results suggest the possibility of manufacturing spin devices based on GNRs doped with Ni atoms.

Structural and optical properties of rare earth-doped (Ba(0.77)Ca(0.23))(1-x)(Sm, Nd, Pr, Yb)(x)TiO(3)

The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba(0.77) Ca(0.23)TiO(3) (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 degrees C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electron microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO(6) octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb(3+) doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm(-1), which is in agreement with lattice dynamics calculations. (c) 2011 American Institute of Physics. [doi:10.1063/1.3594710]

Continuous structural transitions in quasi-one-dimensional classical Wigner crystals

We study the structural phase transitions in confined systems of strongly interacting particles. We consider infinite quasi-one-dimensional systems with different pairwise repulsive interactions in the presence of an external confinement following a power law. Within the framework of Landau's theory, we find the necessary conditions to observe continuous transitions and demonstrate that the only allowed continuous transition is between the single-and the double-chain configurations and that it only takes place when the confinement is parabolic. We determine analytically the behavior of the system at the transition point and calculate the critical exponents. Furthermore, we perform Monte Carlo simulations and find a perfect agreement between theory and numerics.

Structural and optical analysis of GaAsP/GaP core-shell nanowires

The structural and optical properties of GaAsP/GaP core-shell nanowires grown by gas source molecular beam epitaxy were investigated by transmission electron microscopy, Raman spectroscopy, photoluminescence (PL), and magneto-PL. The effects of surface depletion and compositional variations in the ternary alloy manifested as a redshift in GaAsP PL upon surface passivation, and a decrease in redshift in PL in the presence of a magnetic field due to spatial confinement of carriers.

Structural, dielectric, and optical properties of yttrium calcium borate glasses

Structural and optical properties of stable glasses in the Y(2)O(3)-CaO-B(2)O(3) system, containing the same Y/Ca ratio as the YCa(4)O(BO(3))(3) (YCOB) crystal, were determined from Raman and reflectance infrared spectroscopy. Changes in optical functions with composition are associated with an increase in the number of non-bridging oxygen and to calcium/yttrium oxides content. Refractive indexes values (from 1.597 to 1.627 at lambda=2 mu m) are in good agreement with those of the YCOB crystal, an indication that these glasses are potential candidates for optical applications due to their ease of shaping as large bulk samples or fibers.

Fluoride-modified electrical properties of lead borate glasses and electrochemically induced crystallization in the glassy state

Lead fluoroborate glasses were prepared by the melt-quenching technique and characterized in terms of (micro)structural and electrical properties. The study was conducted on as prepared as well as temperature- and/or electric field-treated glass samples. The results show that, in the as-prepared glassy-state materials, electrical conductivity improved with increasing the PbF(2) glass content. This result involves both an increase of the fluoride charge carrier density and, especially, a decrease of the activation energy from a glass structure expansion improving charge carrier mobility. Moreover, for the electric field-treated glass samples, surface crystallization was observed even below the glass transition temperature. As previously proposed in literature, and shown here, the occurrence of this phenomenon arose from an electrochemically induced redox reaction at the electrodes, followed by crystallite nucleation. Once nucleated, growth of beta-PbF(2) crystallites, with the indication of incorporating reduced lead ions (Pb(+)), was both (micro)structurally and electrically detectable and analyzed. The overall crystallization-associated features observed here adapt well with the floppy-rigid model that has been proposed to further complete the original continuous-random-network model by Zachariasen for closely addressing not only glasses' structure but also crystallization mechanism. Finally, the crystallization-modified kinetic picture of the glasses' electrical properties, through application of polarization/depolarization measurements originally combined with impedance spectroscopy, was extensively explored. (c) 2008 American Institute of Physics.

Structure and magnetism of homometallic ludwigites: Co(3)O(2)BO(3) versus Fe(3)O(2)BO(3)

We present an extensive study of the structural, magnetic, and thermodynamic properties of the oxyborate Co(3)O(2)BO(3). This is carried out through x-ray diffraction, static and dynamic magnetic susceptibilities, and specific heat experiments in single crystals in a large temperature range. The structure of Co(3)O(2)BO(3) is composed of subunits in the form of three-leg ladders where Co ions with mixed valency are located. The magnetic properties of this Co ludwigite are determined by a competition between superexchange and double-exchange interactions in the low-dimensional subunits. We discuss the observed physical properties in comparison with the only other known homometallic ludwigite, Fe(3)O(2)BO(3). The latter presents a structural distortion in the ladders and two magnetic transitions. Both features are not found in the present study of the Co ludwigite. The reason for these differences in the structural and magnetic behavior of two apparently similar compounds is discussed.

Structural models for yttrium aluminium borate laser glasses: NMR and EPR studies of the system (Y(2)O(3))(0.2)-(Al(2)O(3))(x)-(B(2)O(3))(0.8-x)

The structure of laser glasses in the system (Y(2)O(3))(0.2){(Al(2)O(3))(x))(B(2)O(3))(0.8-x)} (0.15 <= x <= 0.40) has been investigated by means of (11)B, (27)Al, and (89)Y solid state NMR as well as electron spin echo envelope modulation (ESEEM) of Yb-doped samples. The latter technique has been applied for the first time to an aluminoborate glass system. (11)B magic-angle spinning (MAS)-NMR spectra reveal that, while the majority of the boron atoms are three-coordinated over the entire composition region, the fraction of three-coordinated boron atoms increases significantly with increasing x. Charge balance considerations as well as (11)B NMR lineshape analyses suggest that the dominant borate species are predominantly singly charged metaborate (BO(2/2)O(-)), doubly charged pyroborate (BO(1/2)(O(-))(2)), and (at x = 0.40) triply charged orthoborate groups. As x increases along this series, the average anionic charge per trigonal borate group increases from 1.38 to 2.91. (27)Al MAS-NMR spectra show that the alumina species are present in the coordination states four, five and six, and the fraction of four-coordinated Al increases markedly with increasing x. All of the Al coordination states are in intimate contact with both the three-and the four-coordinate boron species and vice versa, as indicated by (11)B/(27)Al rotational echo double resonance (REDOR) data. These results are consistent with the formation of a homogeneous, non-segregated glass structure. (89)Y solid state NMR spectra show a significant chemical shift trend, reflecting that the second coordination sphere becomes increasingly ""aluminate-like'' with increasing x. This conclusion is supported by electron spin echo envelope modulation (ESEEM) data of Yb-doped glasses, which indicate that both borate and aluminate species participate in the medium range structure of the rare-earth ions, consistent with a random spatial distribution of the glass components.