ABSTRACT
OBJECTIVE@#To build a helical CT projection data restoration model at random low-dose levels.@*METHODS@#We used a noise estimation module to achieve noise estimation and obtained a low-dose projection noise variance map, which was used to guide projection data recovery by the projection data restoration module. A filtering back-projection algorithm (FBP) was finally used to reconstruct the images. The 3D wavelet group residual dense network (3DWGRDN) was adopted to build the network architecture of the noise estimation and projection data restoration module using asymmetric loss and total variational regularization. For validation of the model, 1/10 and 1/15 of normal dose helical CT images were restored using the proposed model and 3 other restoration models (IRLNet, REDCNN and MWResNet), and the results were visually and quantitatively compared.@*RESULTS@#Quantitative comparisons of the restored images showed that the proposed helical CT projection data restoration model increased the structural similarity index by 5.79% to 17.46% compared with the other restoration algorithms (P < 0.05). The image quality scores of the proposed method rated by clinical radiologists ranged from 7.19% to 17.38%, significantly higher than the other restoration algorithms (P < 0.05).@*CONCLUSION@#The proposed method can effectively suppress noises and reduce artifacts in the projection data at different low-dose levels while preserving the integrity of the edges and fine details of the reconstructed CT images.
Subject(s)
Algorithms , Artifacts , Tomography, Spiral Computed , Tomography, X-Ray Computed/methodsABSTRACT
OBJECTIVE@#To propose an adaptive weighted CT metal artifact reduce algorithm that combines projection interpolation and physical correction.@*METHODS@#A normalized metal projection interpolation algorithm was used to obtain the initial corrected projection data. A metal physical correction model was then introduced to obtain the physically corrected projection data. To verify the effectiveness of the method, we conducted experiments using simulation data and clinical data. For the simulation data, the quantitative indicators PSNR and SSIM were used for evaluation, while for the clinical data, the resultant images were evaluated by imaging experts to compare the artifact-reducing performance of different methods.@*RESULTS@#For the simulation data, the proposed method improved the PSNR value by at least 0.2 dB and resulted in the highest SSIM value among the methods for comparison. The experiment with the clinical data showed that the imaging experts gave the highest scores of 3.616±0.338 (in a 5-point scale) to the images processed using the proposed method, which had significant better artifact-reducing performance than the other methods (P < 0.001).@*CONCLUSION@#The metal artifact reduction algorithm proposed herein can effectively reduce metal artifacts while preserving the tissue structure information and reducing the generation of new artifacts.
Subject(s)
Algorithms , Artifacts , Image Processing, Computer-Assisted/methods , Metals , Phantoms, Imaging , Tomography, X-Ray Computed/methodsABSTRACT
Aim To explore the effect of endoplasmic reticulum (ER) stress-related exosomes derived from hepatocellular carcinoma (HCC) cells on the M2 polarization of macrophages via Toll-like receptor 4 (TLR4) and the underlying mechanism. Methods Western blot experiments were conducted to evaluate the GRP78 levels in HCC tissues and HCC cells with or without pre-treatment of tunicamycin and the identification of the isolated exosomes. Immunohistochemical staining was also employed to detect the expression of GRP78 in HCC tissues. Immunofluorescence was used to confirm the effective absorbance of exosomes by macrophages. Flow cytometry ( FCM ) , Western blot and CBA kit were used to detect M2 polarization-asso ciated markers and the expression of TLR4 on macrophages. Affymetrix gene chip and bioinformatics analy-sis were used to screen the differential expression of mRNA in macrophages stimulated by ER stressed-relat- ed exosomes and TLR4 expression. Results In clinical samples, GRP78 expression in liver cancer tissues was higher than that in the adjacent tissues. In cell experiments, tunicamycin (2.5 jxmol • L"1 ) treatment for 24 hours in HCC cells could significantly increase the expression of ER stress marker protein GRP78 compared with control group. Western blot showed that HCC cell-derived exosomes positively expressed exosom- al marker proteins,such as CD63,TSG101 and HSP70, and negatively expressed Calnexin. Interestingly, HSP70-enriched exosomes released by ER-stressed HCC cells were observed. Laser confocal microscopy found that exosomes could be effectively taken up by RAW264.7 macrophages. Flow cytometry and Western blot further indicated that ER stress-related exosomes could significantly up-regulate the expression of CD206, transformed growth factor-beta (TGF-p) and arginase-1 (Arg-1) in macrophages. Meanwhile, these exosomes could promote the secretion of IL-6 and IL- 10,and up-regulate the expression of TLR4 in macrophages. Conclusions ER stressed-HCC cells could promote macrophage M2 polarization by releasing HSP70-enriched exosomes and activating TLR4 signaling.
ABSTRACT
Fourteen compounds were isolated from the ethanol extract of Dalbergiae Odoriferae Lignum by various chromatographic techniques, including column chromatographies on silica gel, Sephadex LH-20 and semi-preparative HPLC. Their structures were determined by spectroscopic techniques as S-3'-hydroxy-7,2',4'-trimethoxyisoxane(1), 2-(2',4'-dimethoxyphenyl)-6-hydroxybenzofuran(2), 2-(2'-hydroxy-4'-methoxyphenyl)-6-methoxybenzofuran(3), 7,2',4'-trimethoxydihydroisoflavone(4), sativanone(5), 3,9-dimethoxy-6H-benzofuro[3,2-c]chromen-6-one(6),(6 aS,11 aS)-homopterocarpin(7),(6 aS,11 aS)-8-hydroxy-3,9-dimethoxypterocarpan(8),(6 aS,11 aS)-3,8,9-trimethoxypterocarpan(9), isodalbergin(10), isoliquiritigenin(11), butein(12), butin(13) and 3,7,4'-trihydroxyflavone(14). Among them, compound 1 was a new compound, while 2 and 3 were new natural products, 6, 8, 9 and 14 were isolated for the first time from Dalbergiae Odoriferae Lignum. Compounds 1-14 were tested for their cytotoxic activity against human hepatoma cell line BEL-7402, human gastric cancer cell line SCG-7901, human lung cancer cell line A549, human chronic myeloid leukemia cell line K562 and HeLa human cervical cancer cellline by MTT method. Compound 1 exhibited significant cytotoxicity with IC_(50) values ranging from 2.85 to 11.62 μg·mL~(-1). In addition, 2, 11 and 12 showed weak cytotoxic activities.
Subject(s)
Humans , Antineoplastic Agents , Chromatography, High Pressure Liquid , HeLa CellsABSTRACT
Ethylene carbodiimide (ECDI) is a chemical coupling agent,more and more studies have focused on the immune tolerance induced by administration of ethylene carbodiimide (ECDI)-fixed syngeneic splenocytes (Ag-SPs) coupled to peptides or to whole myelin proteins,in order to establish a novel and effective tolerance therapy for autoimmune diseases.The mechanisms and applications of immune tolerance induced by Ag-SPs in several kinds of common autoimmune diseases were summarized,and were compared with their counterparts in the traditional treatment.