Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012739 (disseminated intravascular coagulation)
 8,673 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence for a structural precursor of the focal contact in cultured fibroblasts and continuing studies on the development of the precursor and contact are discussed. The structural precursor consists of an F-actin-rich, rib-like fiber within the motile lamellipodium. The focal contact forms beneath the fiber, part of which is retained at the contact as the initial adhesion plaque. Therefore, F-actin is present at the contact from the beginning. Vinculin accumulates at the plaque during a 90-second period after the contact forms. A novel feature of the distribution of talin has been found. The protein is present along the distal margin of the lamellipodium, where it is further concentrated as a series of nodes at the tips of each precursor and between precursors. This distribution of talin is independent of that which develops at the plaque after the contact forms. The structural development of the precursor has been followed with AVEC-DIC optics. The process begins with the development of fine oblique fibers from small structural nodes at the margin of the lamellipodium, and continues with the fusion of the nodes at the margin and inward coalescence of the fibers. It is suggested that talin may function as a cross-linking protein in the convergence of actin filaments at the membrane, while other actin-bundling proteins participate in the inward coalescence of the filaments to form fibers. The F-actin core of the precursor could provide a structural framework against which differences at the external surface of the membrane develop prior to contact formation.
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PMID:A precursor of the focal contact in cultured fibroblasts. 314 Oct 68

Previous work has shown that Trypanosoma cruzi extracellular amastigotes as well as metacyclic trypomastigotes infect cultured cells in a highly specific parasite form-cell type interaction. In this work we have investigated the mode of interaction of both forms with HeLa and Vero cells using scanning electron and confocal fluorescence microscopy. We examined the distribution of several host cell components as well as extracellular matrix elements during cell invasion by both T. cruzi infective forms. Scanning electron microscopy showed that membrane expansions formed during the invasion of cells by extracellular amastigotes. These expansions correspond to small cup-like structures in HeLa cells and are comparatively larger "crater"-like in Vero cells. We detected by confocal microscopy actin-rich structures associated with the internalisation of both infective forms of the parasite that correspond to the membrane expansions. Confocal fluorescence microscopy combining DIC images of cells labelled with monoclonal antibodies to phosphotyrosine, cytoskeletal elements, integrins, and extracellular matrix components revealed that some of the components like gelsolin and alpha-actinin accumulate in actin-rich structures formed in the invasion of amastigotes of both cell types. Others, like vinculin and alpha2 integrin may be present in these structures without evident accumulation. And finally, some actin-rich processes may be devoid of components like fibronectin or alphaV integrin. These studies provide evidence that the repertoire of host cell/extracellular matrix components that engage in the invasion process of T. cruzi forms is cell type- and parasite form-dependent.
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PMID:Actin-rich structures formed during the invasion of cultured cells by infective forms of Trypanosoma cruzi. 1066 10

The purpose of this study was to develop and apply a new model for investigating how the organization and movement of cell-matrix adhesion sites correlate with force generation by corneal fibroblasts on a fibrillar collagen extracellular matrix. Primary cultures of rabbit corneal fibroblasts were transfected using a vector encoding GFP-zyxin to allow visualization of adhesion sites. Cells were plated at low density on top of 100 micro m thick fibrillar collagen lattices embedded with 2 micro m diameter red fluorescent beads. Time-lapse imaging was performed at one minute intervals for up to 3 hours. At each time interval, GFP-zyxin, bead and DIC images were acquired in rapid succession using filter wheels. Cells were treated with cytochalasin D and/or Triton X-100 at the end of each experiment. The movements of adhesions and nearby matrix landmarks were measured and correlated from the time-lapse digital images, and the size, intensity and orientation of the adhesions were quantified. GFP-zyxin was detected in adhesions of transfected corneal fibroblasts as confirmed using vinculin counterstaining. Time-lapse imaging revealed extensions and retractions of cell processes and displacements of the fiduciary beads that were similar to control cells. Extending processes exhibited the most complex behavior, with new adhesions continuously forming at the leading edge while existing adhesions moved backward in a retrograde fashion. This process generated tractional forces as indicated by pulling in of the extracellular matrix in front of the cell. Interestingly, during extension, adhesions along the ventral surface of the cell body generally moved toward those at the tip, resulting in contractile-like shortening and matrix compression at the base of lamellipodia. Overall, a high correlation was found between both the magnitude (R=0.87, P<0.001) and direction (R=0.98, P<0.001) of the adhesions and nearby matrix displacements. Cytochalasin D induced rapid and reversible disassembly of adhesions, cell elongation and matrix relaxation, including decompression at the base of the lamellipodia. This new experimental model allows direct, dynamic assessment of cell-matrix interactions on a fibrillar collagen matrix. Our results are consistent with the previously described 'frontal towing' model of cell motility and demonstrate for the first time that this mechanism is employed by cells interacting with a fibrillar extracellular matrix.
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PMID:Direct correlation of collagen matrix deformation with focal adhesion dynamics in living corneal fibroblasts. 1264 33