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Results 351 - 400 of 1894
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Sohka Takayuki - - 2009
ABSTRACT: BACKGROUND: Gradients of morphogens pattern cell fate - a phenomenon that is especially important during development. A simple model system for studying how morphogens pattern cell behavior would overcome difficulties inherent in the study of natural morphogens in vivo. A synthetic biology approach to building such a system is ...
van Zon Jeroen S - - 2009
Phagocytosis is the process by which cells internalize particulate material, and is of central importance to immunity, homeostasis and development. Here, we study the internalization of immunoglobulin G-coated particles in cells transfected with Fcgamma receptors (FcgammaRs) through the formation of an enveloping phagocytic cup. Using confocal microscopy, we precisely track ...
Kim Mun Ju - - 2009
T-killer cells of the immune system eliminate virus-infected and tumorous cells through direct cell-cell interactions. Reorientation of the killing apparatus inside the T cell to the T-cell interface with the target cell ensures specificity of the immune response. The killing apparatus can also oscillate next to the cell-cell interface. When ...
Baker Ruth E - - 2009
Since the discovery of gene products oscillating during the formation of vertebral segments, much attention has been directed toward eluciating the molecular basis of the so-called segmentation clock. What research has told us is, that even in the most simple vertebrates, enormously complicated gene networks act in each cell to ...
Hernandez Rosa - - 2009
Although the role of invasion in the virulence of Candida albicans has been demonstrated, the mechanism that governs fungal invasion is not fully understood. Among the tools that exist to fill these gaps in knowledge, in vitro tissue models based on reconstituted human epithelia (RHE) have already been developed. Such ...
Biton Y Y - - 2009
We present a theoretical model to explain recent observations of the orientational response of cells to unidirectional curvature. Experiments show that some cell types when plated on a rigid cylindrical surface tend to reorient their shape and stress fibers along the axis of the cylinder, while others align their stress ...
Kam Yoonseok - - 2009
BACKGROUND: Traditional in vitro cell invasion assays focus on measuring one cell parameter at a time and are often less than ideal in terms of reproducibility and quantification. Further, many techniques are not suitable for quantifying the advancing margin of collectively migrating cells, arguably the most important area of activity ...
Nogueira-Ferreira F H - - 2009
We studied the behavior of virgin queens of the stingless bee species Schwarziana quadripunctata, Paratrigona lineata and Tetragona clavipes, investigating internal nest activities, including the cell provisioning and oviposition process. We made direct observation of queen behavior, with the aid of video filming. Forty-four virgin queens of S. quadripunctata were ...
Cailliau Katia - - 2009
To study protein function in cellular signaling, manual microinjection is a direct technique, but limited by the small size of many cells. The giant vertebrate cell, the Xenopus laevis oocyte, is a perfect model system to perform these studies. Oocytes are numerous and synchronous cells, arrested in the G2 phase ...
Veronika Merlin - - 2009
High content screening techniques are increasingly used to understand the regulation and progression of cell motility. The demand of new platforms, coupled with availability of terabytes of data has challenged the traditional technique of identifying cell populations by manual methods and resulted in development of high-dimensional analytical methods. In this ...
Kim Sean H J - - 2009
Three-dimensional (3D) embedded cell cultures provide an appropriate physiological environment to reconstruct features of early glandular epithelial cancer. Although these are orders of magnitude simpler than tissues, they too are complex systems that have proven challenging to understand. We used agent-based, discrete event simulation modeling methods to build working hypotheses ...
Lee Timothy K - - 2009
Nearly identical cells can exhibit substantially different responses to the same stimulus. We monitored the nuclear localization dynamics of nuclear factor kappaB (NF-kappaB) in single cells stimulated with tumor necrosis factor-alpha (TNF-alpha) and lipopolysaccharide (LPS). Cells stimulated with TNF-alpha have quantitative differences in NF-kappaB nuclear localization, whereas LPS-stimulated cells can ...
Moon James J - - 2009
Over the last decade, significant advances have been made in the methodology for studying immune responses in vivo. It is now possible to follow almost every aspect of pathogen-specific immunity using in vivo models that incorporate physiological infectious doses and natural routes of infection. This new ability to study immunity ...
Crouch Adam S - - 2009
In this study, we have used nanoimprinting to create a range of micro- and nanoscale gratings, or their combination, in bulk polystyrene plates to investigate anisotropic cell behaviors of human dermal fibroblasts with respect to the aspect ratio (depth/width) of gratings. The depth and width of the polystyrene gratings both ...
Timp Winston - - 2009
We report on the physical parameters governing prokaryotic cell-to-cell signaling in a model biofilm. The model biofilm is comprised of bacteria that are genetically engineered to transmit and receive quorum-sensing (QS) signals. The model is formed using arrays of time-shared, holographic optical traps in conjunction with microfluidics to precisely position ...
Mishra, Bikash
Fuel cells are promising technology to meet the energy need of the future. This alternative energy source is clean and efficient, and with the continuous decrease in fossil fuel resources, one of the best bets towards sustaining our power needs. Fuel cells are being used in automobiles as well as ...
Kiang, Lee K.
We consider a sensor that is subject to false-positive and false-negative errors. The sensor searches for stationary threat objects such as ballistic missile launchers or improvised explosive devices. The objects are located in a certain area of interest, which is divided into area-cells. The area-cells are defined such that each ...
Choi Kyung-Suk - - 2008
A classically identified "notochordal" cell population in the nucleus pulposus is thought to regulate disk homeostasis. However, the embryonic origin of these cells has been under dispute for >60 years. Here we provide the first direct evidence that all cell types in the adult mouse nucleus pulposus are derived from ...
Voigt, Ina K.
It is well known that all cells of the Voronoi diagram of a Delaunay set are polytopes. For a finite point set, all these cells are still polyhedra. So the question arises, if this observation holds for all discrete point sets: Are always all Voronoi cells of an arbitrary, infinite ...
Chen L Leon - - 2009
Aberrantly regulated cell motility is a hallmark of cancer cells. A hybrid agent-based model has been developed to investigate the synergistic and antagonistic cell motility-impacting effects of three microenvironment variables simultaneously: chemoattraction, haptotactic permission, and biomechanical constraint or resistance. Reflecting distinct cell-specific intracellular machinery, the cancer cells are modeled as ...
Dailey H L - - 2009
The acute respiratory distress syndrome (ARDS) is characterized by fluid accumulation in small pulmonary airways. The reopening of these fluid-filled airways involves the propagation of an air-liquid interface that exerts injurious hydrodynamic stresses on the epithelial cells (EpC) lining the airway walls. Previous experimental studies have demonstrated that these hydrodynamic ...
Smits Anke M - - 2009
Development involves an interplay between various cell types from their birth to their disappearance by differentiation, migration, or death. Analyzing these interactions provides insights into their roles during the formation of a new organism. As a study tool for these interactions, we have created a model based on embryoid bodies ...
Yguel, Manuel
Reliable and efficient perception in dynamic environments especially in densely cluttered environments is still a challenge today. Most of the systems used for target tracking are based on object models. Such approaches usually fail in complex environments with a variety of different moving obstacles. In this report, we propose a ...
Harvey M J - - 2008
Accelerator processors like the new Cell processor are extending the traditional platforms for scientific computation, allowing orders of magnitude more floating-point operations per second (flops) compared to standard central processing units. However, they currently lack double-precision support and support for some IEEE 754 capabilities. In this work, we develop a ...
Falou Omar - - 2008
The high frequency backscatter from cells with a nucleus to cell volume ratio of 0.50 cannot be adequately modeled as a homogeneous sphere. It was hypothesized that the cytoplasm of such cells is of fluid nature. This work attempts to model the ultrasound backscatter (10-62 MHz) from some non-nucleated biological ...
Linge Svein Ohm - - 2008
AIMS: To compute the effects of parameter perturbations for single ischemic cardiac cells, and to determine how perturbations influenced the tendency for the cells to undergo spontaneous depolarization (automaticity) during 20 min of acute ischemia. METHODS: A modified Luo-Rudy 1 cell model was used. Since the range of biological variation ...
Seale, André P
Thesis (Ph. D.)--University of Hawaii at Manoa, 2002.
Slater Jennifer L - - 2009
The production of neurons to form the mammalian cortex, known as embryonic cortical neurogenesis, is a complex developmental process. Insight into the process of cell division during neurogenesis is provided by murine cortical cell lineage trees, recorded through experimental observation. Recurring patterns within cell lineage trees may be indicative of ...
Aubert M - - 2008
We examine the consequences of long-range effects on tumour cell migration. Our starting point are previous results of ours where we have shown that the migration patterns of glioma cells are best interpreted if one assumes attractive interactions between cells. Here we complement the cellular automaton model previously introduced by ...
Hutson M Shane - - 2008
Previous 2D and 3D models concluded that cell sorting requires cytoskeletal fluctuations and is stalled by high tension at heterotypic interfaces. New deterministic and stochastic models show that this is not true in 3D. Sorting in 3D involves both topological untangling and domain coalescence. Coalescence requires fluctuations and low tension, ...
Rubenstein Brenda M - - 2008
In this work, a cellular Potts model based on the differential adhesion hypothesis is employed to analyze the relative importance of select cell-cell and cell-extracellular matrix (ECM) contacts in glioma invasion. To perform these simulations, three types of cells and two ECM components are included. The inclusion of explicit ECM ...
Kapitanov Venedikt A - - 2008
We report investigations on newly designed compact photoacoustic gas cell resonator for laser gas analysis. This photoacoustic cell has a resonator with two times sensitivity compared with the previous result. Sensitivity comparisons between the simulation and the experimental results have been done. The comparisons show predicted result matches well with ...
Volfson Dmitri - - 2008
The structure of bacterial populations is governed by the interplay of many physical and biological factors, ranging from properties of surrounding aqueous media and substrates to cell-cell communication and gene expression in individual cells. The biomechanical interactions arising from the growth and division of individual cells in confined environments are ...
Campbell Stuart G - - 2008
The mechanical properties of myocardium vary across the transmural aspect of the left ventricular wall. Some of these functional heterogeneities may be related to differences in excitation-contraction coupling characteristics that have been observed in cells isolated from the epicardial, mid-myocardial and endocardial regions of the left ventricle of many species, ...
Backes Tracy M - - 2009
We construct and implement a stochastic model of convergent extension, using a minimal set of assumptions on cell behavior. In addition to the basic assumptions of volume conservation, random cell motion, and cell-cell and cell-ECM adhesion, and a non-standard assumption that cytoskeletal polymerization generates an internal pressure tending to keep ...
Chao Dennis L DL Vaccine and Infectious Disease Institute, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA. - - 2008
Clonal expansion of premalignant lesions is an important step in the progression to cancer. This process is commonly considered to be a consequence of sustaining a proliferative mutation. Here, we investigate whether the growth trajectory of clones can be better described by a model in which clone growth does not ...
Meireles, Martine
This study reports a numerical approach for modeling the hydraulic resistance of a filter cake of deformable cells. First, a mechanical and osmotic model that describes the volume fraction of solids in a bed of yeast cells as a function of the compressive pressure it experiences is presented. The effects ...
Meillaud, Fanny
A simple theoretical model for pin/nip-type muc-Si:H solar cells is presented. It is based on a superposition of a drift-dominated collection model and of the classical drift-diffusion transport model of the pn-diode. The model is the basis for a solar cell equivalent circuit, identical to the one introduced by Merten ...
Painter K J - - 2009
The extracellular matrix (ECM) is a highly organised structure with the capacity to direct cell migration through their tendency to follow matrix fibres, a process known as contact guidance. Amoeboid cell populations migrate in the ECM by making frequent shape changes and have minimal impact on its structure. Mesenchymal cells ...
Lee, Daniel W.
Monolithic porous ceramic and porous polystyrene microcarriers were examined as supports for large scale mammalian cell culture. Vero cells and transformed baby hamster kidney (BHK) cells which produced human transferrin were grown in three different reactor configurations: a fixed bed ceramic perfusion system, an airlift systemwith draft tube made of ...
Damiand, Guillaume
In this paper, we present an algorithm for computing efficiently homology generators of 3D subdivided orientable objects which can contain tunnels and cavities. Starting with an initial subdivision, represented with a generalized map where every cell is a topological ball, the number of cells is reduced using simplification operations (removal ...
Canić Suncica - - 2008
Auricular elastic cartilage is a potential source for lining of luminal surfaces of implantable vascular devices, such as stents and left ventricular assist devices with the purpose to improve their biocompatibility. Auricular chondrocytes are easily accessible, harvested, and isolated, and they have been shown to provide a strong adherent cell ...
Kryukov A K - - 2008
We study collective phenomena in highly heterogeneous cardiac cell culture and its models. A cardiac culture is a mixture of passive (fibroblasts), oscillatory (pacemakers), and excitable (myocytes) cells. There is also heterogeneity within each type of cell as well. Results of in vitro experiments are modelled by Luo-Rudy and FitzHugh-Nagumo ...
Huang, Jun
A KINETIC STUDY OF THE T CELL RECOGNITION MECHANISM
Stenlund Hans - - 2008
In this study, the orthogonal projections to latent structures discriminant analysis (OPLS-DA) method was used to assess the in situ chemical composition of two different cell types in mouse liver samples, hepatocytes and erythrocytes. High spatial resolution FT-IR microspectroscopy equipped with a focal plan array (FPA) detector is capable of ...
Painter Scott - - 2008
Dewatered or "dry" grid cells in the USGS ground water modeling software MODFLOW may cause nonphysical artifacts, trigger convergence failures, or interfere with parameter estimation. These difficulties can be avoided in two dimensions by modifying the spatial differencing scheme and the iterative procedure used to resolve nonlinearities. Specifically, the spatial ...
Bur Michael - - 2009
A modified Astra type multistage liquid impinger (MSLI) with integrated bronchial cell monolayers was used to study deposition and subsequent drug absorption on in vitro models of the human airway epithelial barrier. Inverted cell culture of Calu-3 cells on the bottom side of cell culture filter inserts was integrated into ...
Wenzhong Gao, Jiaxin Ning
The fuel cell is a potential alternative energy source for an electric vehicle powertrain. The wide range of frequency spectrum generated by different types of power electronic converter in the fuel cell power conditioning unit causes ripples in the current drawn from fuel cells, and thus affects fuel cell performance ...
Acevedo Cristian A - - 2009
The use of fibrin in tissue engineering has greatly increased over the last 10 years. The aim of this research was to develop a mathematical model to relate the microcapsule-size and cell-load to growth and oxygen depletion. Keratinocytes were isolated from rat skins and microencapsulated dropping fibrinogen and thrombin solutions. ...
Jang Wonhee - - 2008
Little is known about how the sizes of specific organs and tissues are regulated. To try to understand these mechanisms, we have been using a combination of modelling and experiments to study the simple system Dictyostelium discoideum, which forms approximately 20000 cell groups. We found that cells secrete a factor, ...
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