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Proper functioning of the immune system depends on coordinated intercellular communication that occurs in the "immunological synapse". This is the contact area of cell-cell conjugates where information is transferred via segregated clusters of proteins. Vast experimental datasets on its assembly are available, and mathematical and computational modeling represent a useful tool to integrate...
This study addresses a technique to explore mechanical role of intracellular structures by using a triton cytoskeleton model (TC model) for traction force measurements. Inhibition of signaling pathways of myosin light chain phosphorylation, possibly being induced by disruption of mictotubules, is also performed. Traction forces for the TC model significantly decreased compared to control. In contrast,...
Glycoproteins serve as ligands on metastatic cancer cells to mediate labile adhesive interactions with the vascular endothelium. The sub-second transience of carbohydrate-protein bonding events poses challenges for quantification of adhesion by optical tracking. We report the development of a simple, shape- based algorithm with novelty in its application to high spatiotemporal resolution tracking...
We fabricated micro flow channel based on the collagen tunnel for in vitro BBB blood capillary model using collagen gel tunnel, PDMS and infrared laser. This flow channel system can add the influence of shear stress to EC and evaluate the permeability by continuous microfluidic flow during cultivation. This system is expected to become a novel tool for emulating in vivo permeability of drug candidates...
A Fourier transform technique has been used to enhance the genome periodicities when analyzing the distributions of independent nucleotides and dinucleotides. These periodicities are varying from 2 to 500 bp. In this paper we focus on the 3 and 10.5 periodicities. The 3-base periodicity is characteristic for the protein-coding sequences only. The source of the approximately 10.5-base sequence period...
The electromotility of cochlear outer hair cells (OHCs) is a required process for normal hearing, and involves a membrane-based mechanism in which the transmembrane protein, prestin, plays a central role. We have investigated the contribution of prestin to the mechanics and electromechanics of the cell membrane using membrane tethers formed from human embryonic kidney cells. Our results suggest that...
It is commonly recognized that damage to bone tissue begins to occur in response to these supra-physiologic mechanical loading. Parathyroid hormone (PTH) plays a key role on the anabolic effects of osteoblast. However, the effects of N-terminal 1-34 fragment of human PTH (hPTHl-34) on osteoblast under supra-threshold mechanical loading are unknown. We recently used a stretch-induced from the hypotonic...
Recent studies demonstrate that osteocyte processes directly attach to the canalicular wall at discrete, infrequent collagen hillocks, most likely via integrins. In the current paper, we develop a model for these attachment complexes to determine whether they would induce focal strain amplification. Our model predicts that axial strains on the osteocyte process membrane in the vicinity of integrin-based...
Rat aortic fibroblasts were cultured either subconfluent (<20%) or confluent (>80%). Western blotting was conducted to evaluate the amount of two phenotype markers of smooth muscle cells (SMCs), SM alpha-actin (alpha-SMA) and SM myosin heavy chain (SM-MHC). The results showed thatwere native fibroblasts and confluent fibroblasts were myofibroblasts. These two types of cell were then plated on...
We present a simple receding meniscus induced method to capture non-adherent yeast cells onto microwells inside microfluidic channels. Microwells were fabricated by capillary molding onto glass substrate using a UV curable polyurethane acrylate (PUA) solution, leading to well-defined, robust microstructures. A cell suspension of the budding yeast, Saccharomyces cerevisiae, was introduced into microfluidic...
Mechanisms controlling actin polymerization at cell edges remain unclear. To measure the spatiotemporal distribution of edge ruffling, time-lapse optical images of cells expressing fluorescent actin were acquired during a step increase in fluid shear stress and were segmented using an active contour algorithm. Intensity profiles directed normal to the cell boundary were computed, and the spatial distribution...
With the ultimate goal to engineer a meniscus substitute based on autologous cells, we aimed this work at identifying (i) a human cell source capable of generating fibrocartilaginous tissues and (ii) a culture environment promoting the development of bi-zonal constructs, resembling the complex structure and function of a meniscus. The post-expansion differentiation capacity of different chondrogenic...
The purpose of this paper is to introduce our design for transducing forces on the order of tens of piconewtons by optically measuring deflection of a microfabricated beam tip as it pulls on an array of flexible structures such as axons in an array of laminin-printed neurons. To achieve this we have designed polymeric beams with spring constants on the order of 10pN/mum. We have fabricated circular...
The purpose of this paper is to introduce our design for transducing forces on the order of tens of piconewtons by optically measuring deflection of a microfabricated beam tip as it pulls on an array of flexible structures such as axons in an array of laminin-printed neurons. To achieve this we have designed polymeric beams with spring constants on the order of 10pN/mum. We have fabricated circular...
With the ultimate goal to engineer a meniscus substitute based on autologous cells, we aimed this work at identifying (i) a human cell source capable of generating fibrocartilaginous tissues and (ii) a culture environment promoting the development of bi-zonal constructs, resembling the complex structure and function of a meniscus. The post-expansion differentiation capacity of different chondrogenic...
There is increasing experimental evidence suggesting that extracellular and intracellular mechanical forces and deformations have a profound influence on a wide range of cell behavior such as growth, cell division and apoptosis (programmed cell death). In order to explore how cells adapt to applied controlled lateral deformations, we developed a novel functionalized micro force sensor that forms localized...
Aureococcus anophagefferens, a harmful bloom-forming alga responsible for brown tides in estuaries of the Middle Atlantic U.S., has been investigated by atomic force microscopy for the first time, using probes functionalized with a monoclonal antibody specific for the alga. The rupture force between a single monoclonal antibody and the surface of A. anophagefferens was experimentally found to be 246...
Summary form only given. Platelets adhesion occurs at focal adhesions (FA), where cell-membrane receptors bind specifically to substrate proteins and couple to each other and to the cytoskeleton via various cellular proteins. Some of the reactions that follow the ligand-receptor binding at the FA may affect mechanical determinants of the cell-substrate attachment. The resulting molecular structure...
This paper presents a study on force enhancement and mechanisms of contraction in skeletal muscle. Force enhancement was evaluated in four conceptually different experimental preparations: in vivo human muscles activated through voluntary contractions; isolated, in situ muscle preparations (typically the cat soleus), isolated single fibres (typically from the lumbrical muscles of the frog), and isolated...
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