Current Issue : April - June Volume : 2013 Issue Number : 2 Articles : 5 Articles
Background: Bioartificial liver systems, designed to support patients with liver failure,\r\nare composed of bioreactors and functional hepatocytes. Immunological rejection of\r\nthe embedded hepatocytes by the host immune system is a serious concern that\r\ncrucially degrades the performance of the device. Induced pluripotent stem (iPS) cells\r\nare considered a desirable source for bioartificial liver systems, because patient-derived\r\niPS cells are free from immunological rejection. The purpose of this paper was to test\r\nthe feasibility of a bioartificial liver system with iPS cell-derived hepatocyte-like cells.\r\nMethods: Mouse iPS cells were differentiated into hepatocyte-like cells by a multi-step\r\ndifferentiation protocol via embryoid bodies and definitive endoderm. Differentiation of\r\niPS cells was evaluated by morphology, PCR assay, and functional assays. iPS\r\ncell-derived hepatocyte-like cells were cultured in a bioreactor module with a pore size\r\nof 0.2 �µm for 7 days. The amount of albumin secreted into the circulating medium was\r\nanalyzed by ELISA. Additionally, after a 7-day culture in a bioreactor module, cells were\r\nobserved by a scanning electron microscope.\r\nResults: At the final stage of the differentiation program, iPS cells changed their\r\nmorphology to a polygonal shape with two nucleoli and enriched cytoplasmic\r\ngranules. Transmission electron microscope analysis revealed their polygonal shape,\r\nglycogen deposition in the cytoplasm, microvilli on their surfaces, and a duct-like\r\narrangement. PCR analysis showed increased expression of albumin mRNA over the\r\ncourse of the differentiation program. Albumin and urea production was also observed.\r\niPS-Heps culture in bioreactor modules showed the accumulation of albumin in the\r\nmedium for up to 7 days. Scanning electron microscopy revealed the attachment of\r\ncell clusters to the hollow fibers of the module. These results indicated that iPS cells\r\nwere differentiated into hepatocyte-like cells after culture for 7 days in a bioreactor\r\nmodule with a pore size of 0.2 �µm.\r\nConclusion: We consider the combination of a bioreactor module with a 0.2-�µm pore\r\nmembrane and embedded hepatocytes differentiated from iPS cells to be a promising\r\noption for bioartificial liver systems. This paper provides the basic concept and\r\npreliminary data for an iPS cell-oriented bioartificial liver system.\r\nPACS code: 87. Biological and medical physics, 87.85.-d Biomedical engineering, 87.85.Lf\r\nTissue engineering, 87.85.Tu Modeling biomedical systems...
Background: Digital mammography is the most reliable imaging modality for breast\r\ncarcinoma diagnosis and breast micro-calcifications is regarded as one of the most\r\nimportant signs on imaging diagnosis. In this paper, a computer-aided diagnosis\r\n(CAD) system is presented for breast micro-calcifications based on dual-tree complex\r\nwavelet transform (DT-CWT) to facilitate radiologists like double reading.\r\nMethods: Firstly, 25 abnormal ROIs were extracted according to the center and\r\ndiameter of the lesions manually and 25 normal ROIs were selected randomly. Then\r\nmicro-calcifications were segmented by combining space and frequency domain\r\ntechniques. We extracted three texture features based on wavelet (Haar, DB4,\r\nDT-CWT) transform. Totally 14 descriptors were introduced to define the\r\ncharacteristics of the suspicious micro-calcifications. Principal Component Analysis\r\n(PCA) was used to transform these descriptors to a compact and efficient vector\r\nexpression. Support Vector Machine (SVM) classifier was used to classify potential\r\nmicro-calcifications. Finally, we used the receiver operating characteristic (ROC) curve\r\nand free-response operating characteristic (FROC) curve to evaluate the performance\r\nof the CAD system.\r\nResults: The results of SVM classifications based on different wavelets shows DT-CWT\r\nhas a better performance. Compared with other results, DT-CWT method achieved\r\nan accuracy of 96% and 100% for the classification of normal and abnormal ROIs,\r\nand the classification of benign and malignant micro-calcifications respectively. In\r\nFROC analysis, our CAD system for clinical dataset detection achieved a sensitivity of\r\n83.5% at a false positive per image of 1.85.\r\nConclusions: Compared with general wavelets, DT-CWT could describe the features\r\nmore effectively, and our CAD system had a competitive performance....
Background: The aim of this study was to evaluate the concept of a wearable\r\ndevice and, specifically: 1) to design and implement analysis procedures to extract\r\nclinically relevant information from data recorded using the wearable system; 2) to\r\nevaluate the design and placement of the strain sensors.\r\nMethods: Different kinds of trunk movements performed by a healthy subject were\r\nacquired as a comprehensive data set of 639 multivariate time series and off-line\r\nanalyzed. The space of multivariate signals recorded by the strain sensors was\r\nreduced by means of Principal Components Analysis, and compared with the\r\nunivariate angles contemporaneously measured by an inertial sensor.\r\nResults: Very high correlation between the two kinds of signals showed the\r\nusefulness of the garment for the quantification of the movements� range of motion\r\nthat caused at least one strain sensor to lengthen or shorten accordingly. The\r\nrepeatability of signals was also studied. The layout of a next garment prototype was\r\ndesigned, with additional strain sensors placed across the front and hips, able to\r\nmonitor a wider set of trunk motor tasks.\r\nConclusions: The proposed technologies and methods would offer a low-cost and\r\nunobtrusive approach to trunk motor rehabilitation...
Introduction: This paper shows the influence of a measurement method of features\r\nin the diagnosis of Hashimoto�s disease. Sensitivity of the algorithm to changes in\r\nthe parameters of the ROI, namely shift, resizing and rotation, has been presented.\r\nThe obtained results were also compared to the methods known from the literature\r\nin which decision trees or average gray level thresholding are used.\r\nMaterial: In the study, 288 images obtained from patients with Hashimoto�s disease\r\nand 236 images from healthy subjects have been analyzed. For each person, an\r\nultrasound examination of the left and right thyroid lobe in transverse and\r\nlongitudinal sections has been performed.\r\nMethod: With the use of the developed algorithm, a discriminant analysis has been\r\nconducted for the following five options: linear, diaglinear, quadratic, diagquadratic\r\nand mahalanobis. The left and right thyroid lobes have been analyzed both together\r\nand separately in transverse and longitudinal sections. In addition, the algorithm\r\nenabled to analyze specificity and sensitivity as well as the impact of sensitivity of\r\nROI shift, repositioning and rotation on the measured features.\r\nResults and summary: The analysis has shown that the highest accuracy was\r\nobtained for the longitudinal section (LD) with the method of linear, yielding\r\nsensitivity = 76%, specificity = 95% and accuracy ACC = 84%. The conducted\r\nsensitivity assessment confirms that changes in the position and size of the ROI have\r\nlittle effect on sensitivity and specificity. The analysis of all cases, that is, images of\r\nthe left and right thyroid lobes in transverse and longitudinal sections, has shown\r\nspecificity ranging from 60% to 95% and sensitivity from 62% to 89%. Additionally, it\r\nwas shown that the value of ACC for the method using decision trees as a classifier is\r\nequal to 84% for the analyzed data. Thresholding of average brightness of the ROI\r\ngave ACC equal to 76%....
Background: Tissue engineering represents a promising new method for treating\r\nheart valve diseases. The aim of this study was evaluate the importance of\r\nconditioning procedures of tissue engineered polyurethane heart valve prostheses\r\nby the comparison of static and dynamic cultivation methods.\r\nMethods: Human vascular endothelial cells (ECs) and fibroblasts (FBs) were obtained\r\nfrom saphenous vein segments. Polyurethane scaffolds (n = 10) were primarily seeded\r\nwith FBs and subsequently with ECs, followed by different cultivation methods of cell\r\nlayers (A: static, B: dynamic). Group A was statically cultivated for 6 days. Group B was\r\nexposed to low flow conditions (t1= 3 days at 750 ml/min, t2= 2 days at 1100 ml/min)\r\nin a newly developed conditioning bioreactor. Samples were taken after static and\r\ndynamic cultivation and were analyzed by scanning electron microscopy (SEM),\r\nimmunohistochemistry (IHC), and real time polymerase chain reaction (RT-PCR).\r\nResults: SEM results showed a high density of adherent cells on the surface valves from\r\nboth groups. However, better cell distribution and cell behavior was detected in Group\r\nB. IHC staining against CD31 and TE-7 revealed a positive reaction in both groups.\r\nHigher expression of extracellular matrix (ICAM, Collagen IV) was observed in Group B.\r\nRT- PCR demonstrated a higher expression of inflammatory Cytokines in Group B.\r\nConclusion: While conventional cultivation method can be used for the development\r\nof tissue engineered heart valves. Better results can be obtained by performing a\r\nconditioning step that may improve the tolerance of cells to shear stress. The novel\r\npulsatile bioreactor offers an adequate tool for in vitro imp...
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