The benefits of folic acid-modified gold nanoparticles in CT-based molecular imaging: radiation dose reduction and image contrast enhancement

X-ray computed tomography (CT) requires an optimal compromise between image quality and patient dose. While high image quality is an important requirement in CT, the radiation dose must be kept minimal to protect the patients from ionizing radiation-associated risks. The use of probes based on gold nanoparticles (AuNPs) along with active targeting ligands for specific recognition of cancer cells may be one of the balanced solutions. Herein, we report the effect of folic acid (FA)-modified AuNP as a targeted nanoprobe on the contrast enhancement of CT images as well as its potential for patient dose reduction. For this purpose, nasopharyngeal KB cancer cells overexpressing FA receptors were incubated with AuNPs with and without FA modification and imaged in a CT scanner with the following X-ray tube parameters: peak tube voltage of 130�KVp, and tube current�time products of 60, 90, 120, 160 and 250�mAs. Moreover, in order to estimate the radiation dose to which the patient was exposed during a head CT protocol, the CT dose index (CTDI) value was measured by an X-ray electrometer by changing the tube current�time product. Raising the tube current�time product from 60 to 250�mAs significantly increased the absorbed dose from 18�mGy to 75�mGy. This increase was not associated with a significant enhancement of the image quality of the KB cells. However, an obvious increase in image brightness and CT signal intensity (quantified by Hounsfield units HU) were observed in cells exposed to nanoparticles without any increase in the mAs product or radiation dose. Under the same Au concentration, KB cells exposed to FA-modified AuNPs had significantly higher HU and brighter CT images than those of the cells exposed to AuNPs without FA modification. In conclusion, FA-modified AuNP can be considered as a targeted CT nanoprobe with the potential for dose reduction by keeping the required mAs product as low as possible while enhancing image contrast. © 2017 Informa UK Limited, trading as Taylor & Francis Grou

Intestinal protozoa in domestic cats (Carnivora: Felidae, felis catus) in northwestern iran: A cross-sectional study with prevalent of microsporidian and coccidian parasites

Background: In this study, some microsporidial and coccidian parasites were isolated from 103 domestic cats in the Meshkin Shahr area, northwestern Iran during the Jun 2014 to Jun 2015, and their genera were identified using parasitologicamethods with emphasis on their zoonotic importance. Methods: One hundred and three fecal samples of domestic cats were collected and preserved in formalin (10) and conserved in phosphate buffer saline solution, finally examined by microscopy after formalin-ether concentration and specific staining. Preservation in dichromate potassium (2.5) was performed for all coccidian positive samples and then sporulated coccidian oocysts were investigated. Results: The detected parasites were Isospora spp. 6/103(5.8). Microsporidian spores were identified in 46/103 (44.6) of all samples post-stained by the aniline blue staining method. Conclusion: Microsporidial infections were more prevalent in domestic cats. Further studies are needed in the identification of microsporidial spores isolated from infected cats. © 2019, Tehran University of Medical Sciences (TUMS). All rights reserved

Phenotypic and Genome-Wide Analysis of an Antibiotic-Resistant Small Colony Variant (SCV) of Pseudomonas aeruginosa

Small colony variants (SCVs) are slow-growing bacteria, which often show increased resistance to antibiotics and cause latent or recurrent infections. It is therefore important to understand the mechanisms at the basis of this phenotypic switch.One SCV (termed PAO-SCV) was isolated, showing high resistance to gentamicin and to the cephalosporine cefotaxime. PAO-SCV was prone to reversion as evidenced by emergence of large colonies with a frequency of 10(-5) on media without antibiotics while it was stably maintained in presence of gentamicin. PAO-SCV showed a delayed growth, defective motility, and strongly reduced levels of the quorum sensing Pseudomonas quinolone signal (PQS). Whole genome expression analysis further suggested a multi-layered antibiotic resistance mechanism, including simultaneous over-expression of two drug efflux pumps (MexAB-OprM, MexXY-OprM), the LPS modification operon arnBCADTEF, and the PhoP-PhoQ two-component system. Conversely, the genes for the synthesis of PQS were strongly down-regulated in PAO-SCV. Finally, genomic analysis revealed the presence of mutations in phoP and phoQ genes as well as in the mexZ gene encoding a repressor of the mexXY and mexAB-oprM genes. Only one mutation occurred only in REV, at nucleotide 1020 of the tufA gene, a paralog of tufB, both encoding the elongation factor Tu, causing a change of the rarely used aspartic acid codon GAU to the more common GAC, possibly causing an increase of tufA mRNA translation. High expression of phoP and phoQ was confirmed for the SCV variant while the revertant showed expression levels reduced to wild-type levels.By combining data coming from phenotypic, gene expression and proteome analysis, we could demonstrate that resistance to aminoglycosides in one SCV mutant is multifactorial including overexpression of efflux mechanisms, LPS modification and is accompanied by a drastic down-regulation of the Pseudomonas quinolone signal quorum sensing system

Measurement of the Stress State in the Lower Link of the Three-Point Hitch Mechanism

Agricultural machines and their implements are subjected to dynamic loads during farm operations. Depending on the type of operation (e.g. lifting or plowing), lower links of the three-point hitch mechanism are exposed to stresses caused by combination of bending moments and axial forces. In this paper we analyzed influence of the soil resistance during plowing in the lower link and the possibility of its failure. The stresses were measured using strain gauges at locations with uniform stress distribution in order to enable more reliable comparison with finite element analysis (FEA). Recorded stresses vs. time were used for identifying mean stresses and amplitudes for different plowing depth and different tractor speeds. Due to the geometry of the lower links and their joints in the three-point hitch mechanism, during plowing and transferring soil resistance, links are loaded not only by axial forces but also by bending moment in the horizontal plane. Under some assumptions, FEA provided us to make relations between the measured stresses and the loads that caused them. Measured stresses show that links have significant safety margin relative to tractor installed power and soil resistance, which enables the possibility of their design optimization. Obtained results may also serve for further analyses of fatigue life prediction, measurement of the draft forces etc

GPVI and Thromboxane Receptor on Platelets Promote Proinflammatory Macrophage Phenotypes during Cutaneous Inflammation

Platelets are well known for their role in hemostasis but are also increasingly recognized for their supporting role in innate immune responses. Here, we studied the role of platelets in the development of peripheral inflammation and found that platelets colocalize with macrophages in the inflamed tissue outside of blood vessels in different animal models for cutaneous inflammation. Collagen-treatment of macrophages isolated from paws during zymosan-induced inflammation induced thromboxane synthesis through the platelet expressed collagen receptor glycoprotein VI. Deletion of glycoprotein VI or its downstream effector thromboxane A2 receptor (TP) reduced zymosan-induced mechanical allodynia without altering macrophage recruitment or formation of macrophage/platelet complexes. Instead, macrophages in inflamed paws of glycoprotein VI- and TP-deficient mice exhibited an increased expression of anti-inflammatory markers and synthesized less proinflammatory mediators (prostaglandin E-2 and IL6). TP expression on platelets was necessary to mediate increased prostaglandin E2 and IL6 synthesis, whereas TP expression on macrophages was sufficient to decrease the expression of the anti-inflammatory macrophage marker CD206, showing that TP activation on platelets and macrophages regulates different aspects of macrophage activation

Phenotypic and genome-wide analysis of an antibiotic-resistant small colony variant (SCV) of Pseudomonas aeruginosa

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