Current Issue : April - June Volume : 2016 Issue Number : 2 Articles : 4 Articles
Background: Cell-to-cell interactions are complex processes that involve physical\ninteractions, chemical binding, and biological signaling pathways. Identification of\nthe functions of special signaling pathway in cell-to-cell interaction from the very first\ncontact will help characterize the mechanism underlying the interaction and advance\nnew drug discovery.\nMethods: This paper reported a case study of characterizing initial interaction\nbetween leukemia cancer cells and bone marrow stromal cells, through the use of an\noptical tweezers-based cell manipulation tool. Optical traps were used to assemble\nleukemia cells at different positions of the stromal cell layer and enable their interactions\nby applying a small trapping force to maintain the cell contact for a few minutes.\nSpecific drug was used to inhibit the binding of molecules during receptor-ligand mediated\nadhesion.\nResults and conclusions: Our results showed that the amount of adhesion molecule\ncould affect cell adhesion during the first few minutes contact. We also found that\nleukemia cancer cells could migrate on the stromal cell layer, which was dependent\non the adhesion state and activation triggered by specific chemokine. The reported\napproaches provided a new opportunity to investigate cell-to-cell interaction through\nsingle cell adhesion manipulation....
Background: One of the recommended treatments for disorders associated with the\nlower extremity venous insufficiency is the application of external mechanical compression.\nCompression stockings and elastic bandages are widely used for the purpose\nof compression therapy and are usually designed to exert a specified value or range\nof compression on the leg. However, the leg deforms under external compression,\nwhich can lead to undesirable variations in the amount of compression applied by the\ncompression bandages. In this paper, the use of an active compression bandage (ACB),\nwhose compression can be regulated through an electrical signal, is investigated. The\nACB is based on the use of dielectric elastomer actuators. This paper specifically investigates,\nvia both analytical and non-linear numerical simulations, the potential pressure\nthe ACB can apply when the compliancy of the human leg is taken into account. The\nwork underpins the need to account for the compressibility of the leg when designing\ncompression garments for lower extremity venous insufficiency.\nMethods: A mathematical model is used to simulate the volumetric change of a calf\nwhen compressed. Suitable parameters for this calf model are selected from the literature\nwhere the calf, from ankle to knee, is divided into six different regions. An analytical\nelectromechanical model of the ACB, which considers its compliancy as a function\nof its pre-stretch and electricity applied, is used to predict the ACB�s behavior. Based on\nthese calf and ACB analytical models, a simulation is performed to investigate the interaction\nbetween the ACB and the human calf with and without an electrical stimulus\napplied to the ACB. This simulation is validated by non-linear analysis performed using\na software based on the finite element method (FEM). In all simulations, the ACB�s elastomer\nis stretched to a value in the range between 140 and 220 % of its initial length.\nResults: Using data from the literature, the human calf model, which is examined\nin this work, has different compliancy in its different regions. For example, when a\n28.5 mmHg (3.8 kPa) of external compression is applied to the entire calf, the ankle\nshows a 3.7 % of volume change whereas the knee region undergoes a 2.7 % of volume\nchange. The paper presents the actual pressure in the different regions of the calf\nfor different values of the ACB�s stretch ratio when it is either electrically activated or not activated, and when compliancy of the leg is either considered or not considered.\nFor example, results of the performed simulation show that about 10 % variation in\ncompression in the ankle region is expected when the ACB initially applies 6 kPa and\nthe compressibility of the calf is first considered and then not considered. Such a variation\nreduces to 5 % when the initial pressure applied by the ACB reduced by half.\nConclusions: Comparison with non-linear FEM simulations show that the analytical\nmodels used in this work can closely estimate interaction between an active compression\nbandage and a human calf. In addition, compliancy of the leg should not be\nneglected when either designing a compression band or predicting the compressive\nforce it can exert. The methodology proposed in this work can be extended to other\ntypes of elastic compression bandages and garments for biomedical applications....
Background: Cervical cancer remains a major health problem, especially in developing\ncountries. Colposcopic examination is used to detect high-grade lesions in patients\nwith a history of abnormal pap smears. New technologies are needed to improve the\nsensitivity and specificity of this technique. We propose to test the potential of fluorescence\nconfocal microscopy to identify high-grade lesions.\nMethods: We examined the quantification of ex vivo confocal fluorescence microscopy\nto differentiate among normal cervical tissue, low-grade Cervical Intraepithelial\nNeoplasia (CIN), and high-grade CIN. We sought to (1) quantify nuclear morphology\nand tissue architecture features by analyzing images of cervical biopsies; and (2) determine\nthe accuracy of high-grade CIN detection via confocal microscopy relative to\nthe accuracy of detection by colposcopic impression. Forty-six biopsies obtained from\ncolposcopically normal and abnormal cervical sites were evaluated. Confocal images\nwere acquired at different depths from the epithelial surface and histological images\nwere analyzed using in-house software.\nResults: The features calculated from the confocal images compared well with those\nfeatures obtained from the histological images and histopathological reviews of the\nspecimens (obtained by a gynecologic pathologist). The correlations between two\nof these features (the nuclear-cytoplasmic ratio and the average of three nearest\nDelaunay-neighbors distance) and the grade of dysplasia were higher than that of\ncolposcopic impression. The sensitivity of detecting high-grade dysplasia by analysing\nimages collected at the surface of the epithelium, and at 15 and 30 �¼m below the\nepithelial surface were respectively 100, 100, and 92 %.\nConclusions: Quantitative analysis of confocal fluorescence images showed its capacity\nfor discriminating high-grade CIN lesions vs. low-grade CIN lesions and normal\ntissues, at different depth of imaging. This approach could be used to help clinicians\nidentify high-grade CIN in clinical settings....
Background: Atrial fibrillation (AF) is the most common heart rhythm disorder. In\norder for late Gd enhancement cardiovascular magnetic resonance (LGE CMR) to\nameliorate the AF management, the ready availability of the accurate enhancement\nsegmentation is required. However, the computer-aided segmentation of enhancement\nin LGE CMR of AF is still an open question. Additionally, the number of centres\nthat have reported successful application of LGE CMR to guide clinical AF strategies\nremains low, while the debate on LGE CMR�s diagnostic ability for AF still holds. The\naim of this study is to propose a method that reliably distinguishes enhanced (abnormal)\nfrom non-enhanced (healthy) tissue within the left atrial wall of (pre-ablation and\n3 months post-ablation) LGE CMR data-sets from long-standing persistent AF patients\nstudied at our centre.\nMethods: Enhancement segmentation was achieved by employing thresholds benchmarked\nagainst the statistics of the whole left atrial blood-pool (LABP). The test-set\ncross-validation mechanism was applied to determine the input feature representation\nand algorithm that best predict enhancement threshold levels.\nResults: Global normalized intensity threshold levels TPRE = 1 1/4 and TPOST = 1\n5/8 were found to segment enhancement in data-sets acquired pre-ablation and at\n3 months post-ablation, respectively. The segmentation results were corroborated\nby using visual inspection of LGE CMR brightness levels and one endocardial bipolar\nvoltage map. The measured extent of pre-ablation fibrosis fell within the normal range\nfor the specific arrhythmia phenotype. 3D volume renderings of segmented post ablation\nenhancement emulated the expected ablation lesion patterns. By comparing\nour technique with other related approaches that proposed different threshold levels\n(although they also relied on reference regions from within the LABP) for segmenting\nenhancement in LGE CMR data-sets of AF patients, we illustrated that the cut-off levels\nemployed by other centres may not be usable for clinical studies performed in our\ncentre.\nConclusions: The proposed technique has great potential for successful employment\nin the AF management within our centre. It provides a highly desirable validation of\nthe LGE CMR technique for AF studies. Inter-centre differences in the CMR acquisition\nprotocol and image analysis strategy inevitably impede the selection of a universally\noptimal algorithm for segmentation of enhancement in AF studies....
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