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Highlights • A multi-atlas based segmentation method for cardiac PET and SPECT images. • Remarkably different perfusion between single-atlas and multi-atlas based ROIs. • High correlation results between multi-atlas based and manual segmentations. Abstract Purpose We propose a multi-atlas based segmentation method for cardiac PET and SPECT images to deal with the high variability of tracer uptake characteristics in myocardium. In addition, we verify its performance by comparing it to the manual segmentation and single-atlas based approach, using dynamic myocardial PET. Methods Twelve left coronary artery ligated SD rats underwent ([18F]fluoropentyl) triphenylphosphonium salt PET/CT scans. Atlas-based segmentation is based on the spatial normalized template with pre-defined region-of-interest (ROI) for each anatomical or functional structure. To generate multiple left ventricular (LV) atlases, each LV image was segmented manually and divided into angular segments. The segmentation methods performances were compared in regional count information using leave-one-out cross-validation. Additionally, the polar-maps of kinetic parameters were estimated. Results In all images, the highest r 2 template yielded the lowest root-mean-square error (RMSE) between the source image and the best-matching templates ranged between 0.91–0.97 and 0.06–0.11, respectively. The single-atlas and multi-atlas based ROIs yielded remarkably different perfusion distributions: only the multi-atlas based segmentation showed equivalent high correlation results (r 2 = 0.92) with the manual segmentation compared with the single-atlas based (r 2 = 0.88). The high perfusion value underestimation was remarkable in single-atlas based segmentation. Conclusions The main advantage of the proposed multi-atlas based cardiac segmentation method is that it does not require any prior information on the tracer distribution to be incorporated into the image segmentation algorithms. Therefore, the same procedure suggested here is applicable to any other cardiac PET or SPECT imaging agents without modification. [ABSTRACT FROM AUTHOR]

The development of biologically targeted contrast agents for X-ray computed tomography (CT) imaging remains a major challenge. Here, we investigated a green chemistry-based synthesis of lymph node-targeted mannan-capped gold nanoparticles (M-GNPs) as a CT contrast agent. In this study, mannan was used as a reducing and stabilizing agent for gold nanoparticles (AuNPs). M-GNPs were readily internalized by antigen-presenting cells (APCs) through mannose receptors-mediated endocytosis. The M-GNPs, which had a spherical morphology, had an average diameter of 9.18 ± 0.71 nm and surface plasmon resonance (SPR) absorption spectra with maximal absorption at 522 nm. The M-GNPs displayed a concentration-based X-ray attenuation property with a maximum Hounsfield unit (HU) value of 303.2 ± 10.83. The local administration of M-GNPs led to significantly enhanced X-ray contrast for the imaging of popliteal lymph nodes. These findings demonstrated that M-GNPs can be used as biologically targeted contrast agents for CT imaging. [ABSTRACT FROM AUTHOR]

A PtSe2-based edge-contact field-effect transistor (FET) incorporating PtSe2 as the channel material and PtTe2 as the contact metal is fabricated using tellurization on only a selected region. The higher on–off ratio of the PtSe2-based edge-contact device compared to other synthesized PtSe2-based FETs is successfully achieved by reducing the contact resistance. [Display omitted] One-dimensional (1D) edge contact is considered critical to reducing contact resistance between two-dimensional transition-metal dichalcogenides (TMDs) and contact metal and overcoming surface contact effects, such as surface damage and orbital hybridization. Although several studies have investigated edge contact, some problems such as inevitable etching damage and a limited area persist. Herein, a tellurization method is applied to a specific lateral region to fabricate PtTe 2 /PtSe 2 /PtTe 2 edge-contact field-effect transistors (FETs) without etching damage. High-resolution X-ray photoelectron spectroscopy and Raman spectroscopy are used to verify tellurization completion, which is evidenced by the complete transformation of PtSe 2 to PtTe 2 by the substitution of Se atoms with evaporated Te atoms. Furthermore, tellurization is applied to a specific lateral region by utilizing the hexagonal boron nitride to block the interdiffusion of evaporated Te atoms, which is confirmed by Raman spectroscopy and cross-sectional annular dark-field scanning transmission electron microscopy. Finally, the 1D edge-contact FETs fabricated by tellurization demonstrate a higher on–off ratio and carrier mobility than the surface-contact FET. Therefore, this method can be applied to various FETs based on TMDs for improving electrical performance through a reduction in contact resistance. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Recent studies have reported the color change and formation of precipitates containing para-chloroaniline (PCA) after a reaction of sodium hypochlorite (NaOCl) and chlorhexidine (CHX). Alexidine (ALX), a biguanide disinfectant similar to CHX, has greater affinity for bacterial virulence factors than CHX. This study determined by electrospray ionization mass spectrometry (ESI-MS) and scanning electron microscopy (SEM) whether the chemical interaction between ALX and NaOCl results in PCA or precipitates. Methods: ESI-MS was performed on 4 different concentrations of ALX (1%, 0.5%, 0.25%, and 0.125%) with 4% NaOCl to detect the presence of PCA. As control groups, 1% ALX, 0.5% PCA, and a mixture of 2% CHX and 4% NaOCl were analyzed. The formation of precipitates on the dentinal surfaces of premolar root canals treated with the solutions of ALX and NaOCl (AN) or CHX and NaOCl (CN) was observed by SEM and the color change in the reaction solutions was also analyzed. Results: ESI-MS showed that the peak (mass/charge ratio = 128.026) in the PCA spectrum was not detected in any of the 4 AN solutions, whereas the peak was found in the CN solution. SEM revealed precipitates covering dentinal surfaces in the CN solution. The AN solutions produced no precipitate. The AN solutions changed in color from light yellow to transparent with decreasing ALX concentration, whereas peach-brown discoloration was observed in the CN solution. Conclusions: The interaction of ALX and NaOCl did not produce PCA or precipitates, and the color of the reacted solution changed transparent with decreasing ALX concentration. [Copyright &y& Elsevier]

In the present authors’ previous study, sonicated Enterococcus faecalis extracts were shown to suppress the cell cycle progression of human lymphocytes. To study the effect of this microorganism on the function of lymphocytes, the authors investigated the levels of interleukin-2 (IL-2) and interleukin-4 (IL-4) production by T lymphocytes before and after the addition of sonicated E. faecalis extracts. In this study, levels of IL-2 and IL-4 produced from T cells were evaluated by using the quantitative sandwich enzyme immunoassay technique. In response to phytohemagglutinin (PHA) stimulation, T cells produced increased levels of IL-2 and IL-4. However, the expressions of both cytokines were significantly inhibited when PHA-activated T cells were preexposed to 12.5 μg/ml and 25 μg/ml of sonicated E. faecalis extracts (p < 0.05). This effect was concentration-dependent, because the levels of IL-2 and IL-4 expressions were not affected by the addition of a low concentration (5 μg/ml) of sonicated extract. These findings suggest that Th1 and Th2 immunosuppression mediated by E. faecalis could be a part of the pathogenic mechanism of the endodontic failure associated with this microorganism. [Copyright &y& Elsevier]

Carbonic anhydrase IX is overexpressed in many solid tumors including hypoxic tumors and is a potential target for cancer therapy and diagnosis. Reported imaging agents targeting CA-IX are successful mostly in clear cell renal carcinoma as SKRC-52 and no candidate was approved yet in clinical trials for imaging of CA-IX. To validate CA-IX as a valid target for imaging of hypoxic tumor, we designed and synthesized novel [ 18 F]-PET tracer ( 1 ) based on acetazolamide which is one of the well-known CA-IX inhibitors and performed imaging study in CA-IX expressing hypoxic tumor model as 4T1 and HT-29 in vivo models other than SKRC-52. [ 18 F]-acetazolamide ( 1 ) was found to be insufficient for the specific accumulation in CA-IX expressing tumor. This study might be useful to understand in vivo behavior of acetazolamide PET tracer and can contribute to the development of successful PET imaging agents targeting CA-IX in future. Additional study is needed to understand the mechanism of poor targeting of CA-IX, as if CA-IX is not reliable as a sole target for imaging of CA-IX expressing hypoxic solid tumors. [ABSTRACT FROM AUTHOR]