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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adhesion of human and dog platelets to native and collagen-coupled Cuprophan under defined flow conditions was studied by scanning and transmission electron microscopy. Dog platelets, singly adherent to and uniformly distributed on both native and collagen-coupled Cuprophan, extend slender pseudopods across the surface without evidence of degranulation. Human platelets, while not adhering to native Cuprophan, formed irregularly shaped, semi-confluent cytoplasmic sheets on the collagen-coupled surface. Extensive cytoplasmic reorganization and degranulation suggests a post-release state of the human platelets. Aspirin had no apparent effect on either human or dog platelet adhesion or upon the apparent release state of the human platelets.
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PMID:Ultrastructural characteristics of dog and human platelets adherent to native and collagen-coupled cuprophan. 53 1

Adhesion of platelets to collagen fibrils in a stirred system was inhibited by preincubation of platelets with combinations of 2-deoxy-D-glucose and oligomycin or antimycin. The inhibition of adhesion was associated with a decrease in metabolic ATP to 6% of control levels. Without metabolic inhibitors, platelets adherent to collagen fibrils were found to have catabolized approximately 57% of their metabolic ATP, and converted a major part of this to IMP. Storage pool ATP and ADP contents were also diminished in the adherent platelets. Pretreatment with imipramine resulted in 76% inhibition of the release reaction, but only 5% inhibition of adhesion. Imipramine-treated platelets that were adherent to collagen showed significant depletion of metabolic ATP, but markedly diminished conversion of ATP to IMP as compared to control adherent platelets. Inhibition of deamination of platelet AMP by coformycin or erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) did not inhibit adhesion, although platelets adherent to collagen after treatment with these agents showed depletion of metabolic ATP. These studies suggest that adhesion is an energy dependent process, occurring independently of release, and not associated with conversion of ATP to IMP. The energy dependent portions of the adhesion process are probably disc to sphere transformation and pseudopod formation, the ATP threhold requirement is relatively low, and the ATP utilized can probably be regenerated during the adhesion process via glycolysis and oxidative phosphorylation.
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PMID:Relationships of adenine nucleotide metabolism to platelet-collagen adhesion. 58 Sep 88

The mechanism of tendon healing and the role played by the synovial sheath are still obscure and controversial. In the present experimental study free tendon grafts were nourished by synovial fluid only. By morphological and cytochemical techniques viable cells were found in the superficial zones of the tendon, capable of both proliferation and production and production of new collagen. This repair process affected predominantly the ends of the grafts. At the centre of the specimens degenerative changes appeared to an increasing extent throughout the observation period of 12 weeks. Adhesions to the surrounding tissues did not form. It is concluded that fibroblasts, most probably originated from the superficial cell layers of the tendon are capable of regeneration and synthesis of new collagen and that synovial fluid plays an important role in the metabolic exchange of the superficial scantily vascularized areas of the tendon. The observations are discussed in relation to the present concepts of tendon surgery.
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PMID:Synovium as a nutritional medium in tendon grafting. 60 35

Cell Adhesion Factor, complexed to insoluble collagen-coated tissue culture dishes, is required for the attachment of fibroblasts to this substrate. In solution, the factor has no demonstrable affinity for cells in suspension following trypsin-EDTA removal of cells from monolayer. Cell surface receptors for the factor are present during the assay period since cells allowed to recover for 1 h at 37 degrees C, 4 degrees C or in the presence of 10(-6) M cycloheximide show exactly the same kinetics of adhesion as control cells. It is demonstrated that Cell Adhesion Factor acquires affinity for the cell surface only following its binding to collagen.
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PMID:Substrate activation of cell adhesion factor as a prerequisite for cell attachment. 68 Oct 24

Adhesion to collagen was investigated as a function of platelet age in rat platelets. Platelet adherence was measured using EDTA-containing platelet- rich plasma which was added to preparations of collagen fibers clamped between magnetic stirrers by recording changes in light transmission. The plot of light transmission versus logarithm of time was linear and allowed calculation of a slope factor which related to the rate of adherence. Neither the amount of collagen nor the platelet count were limiting in the test. Young platelet populations (less than or equal to 1 day old) were obtained during the recovery phase from immune induced thrombocytopenia. Old platelet populations were prepared by blocking thrombopoiesis with cyclophosphamide. Young platelets showed a moderate but statistically significant increase in adhesivity to collagen but old platelets did not differ significantly from randomly aged platelets in this function. The electrophoretic mobility of platelets was not affected by their age.
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PMID:Effect of platelet age on adhesiveness to collagen and platelet surface charge. 103 40

Adhesion of platelets to several polymer- and protein-coated glass surfaces has been studied in vitro. The apparatus consists of a cylindrical probe rotating in a test tube containing the platelet medium and allows close control of fluid shear and mass transport. Suspensions of washed pig platelets constitute the basic platelet medium, and can be modified by adding back red cells and plasma proteins. Adhesion is measured via 51Cr-labeling of platelets. In the absence of red cells, identical low levels of adhesion were seen on all surfaces and saturation was reached within 2 min. In the presence of red cells, adhesion was greater. Saturation on all surfaces except fibrinogen and collagen again occurred within 2 min. The adhesion levels on polymer surfaces and glass were indistinguishable, while those on albumin were lower and those on fibrinogen were higher. Collagen was the most reactive surface. It did not equilibrate within 15 min., and kinetic data indicated a platelet diffusivity strongly dependent on hematocrit. These effects were attributed to rotational and translational motion of the red cells causing increased diffusion and surface-platelet collision energy.
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PMID:Adhesion of platelets to artificial surfaces: effect of red cells. 127 Apr 59

Glomerular epithelial cells (GEC) maintain glomerular permselectivity and are a target of immunological glomerular injury, which may lead to proliferation or detachment from extracellular matrix (ECM). We studied adhesion mechanisms in rat GEC in culture, focusing on adhesion molecules of the beta 1 integrin family. At early time points (1 hr after plating of cells into culture wells that had been pre-incubated with purified ECM proteins), adhesion of GEC to collagen I, collagen IV, laminin, and fibronectin was inhibited with anti-beta 1 integrin antibody. The peptide RGDS inhibited adhesion to fibronectin and laminin. Immunoprecipitation studies demonstrated the presence of alpha 2, alpha 3, and beta 1 integrins; the alpha 1, alpha 4, alpha 5, alpha 6, alpha v, and beta 3 subunits were undetectable. Adhesion to all ECM proteins was dependent on divalent cations, but the effects of individual cations varied among substrata. In rat GEC, alpha 2 beta 1 and/or alpha 3 beta 1 integrins appear to mediate adhesion to collagen I, collagen IV, and laminin. The alpha 3 beta 1 integrin is also the likely receptor for fibronectin, interacting through an RGD binding site. Furthermore, single integrins or combinations of integrins appear to have distinct ligand-binding functions that are differentially regulated by divalent cations. Characterization of GEC adhesion molecules may facilitate the understanding of mechanisms of glomerular development, and cell detachment or proliferation in immune glomerular injury.
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PMID:Adhesion of rat glomerular epithelial cells to extracellular matrices: role of beta 1 integrins. 128 Jul 1

Regulation of a number of adhesion molecules during neural crest cell migration was studied. The neural crest, a transient embryonic neural epithelium structure, undergoes mesenchymal transformation (epithelial-mesenchymal transition). The cells then migrate, giving rise to a variety of elements including the peripheral nervous system and melanocytes. During migration, neural crest cells do not express functional cell Adhesion Molecules but interact specifically with cell-binding domains in fibronectin molecules. A rat bladder carcinoma cell line was used as an in vitro model to study conversion of epithelial cells to a migratory fibroblast-like state. Conversion can be induced by culture on collagen or exposure to acidic Fibroblast Growth Factor (aFGF). Furthermore, constitutive fibroblast-like transformation can be induced by transfection with cDNA encoding aFGF. Growth factor-producing clones exhibit increased invasive and metastatic properties as compared with non-FGF-producing control cells. This model may provide increased understanding of the role of the different adhesion molecules in processes involving cell remodeling, such as tumor spread and development of metastases.
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PMID:[Adhesion and mobility of embryonic and tumoral cells]. 128 12

Recently, we described a platelet antibody against a putative collagen receptor (P62), which was found in a patient with idiopathic thrombocytopenic purpura (ITP) (Blood 69:1712). We now report a deficiency of the P62 receptor in a young man whose platelets showed defective collagen-induced platelet aggregation. He had a mild bleeding tendency and slight thrombocytopenia. The results of coagulation and fibrinolysis studies were normal. The patient's platelets were partially unresponsive to collagen, although aggregation in response to ADP, thrombin, ristocetin, and calcium ionophore (A23187) was almost normal. Adhesion of his platelets to bovine collagen was markedly reduced. Addition of collagen caused no synthesis of thromboxane (TX)B2 in platelet rich plasma (PRP) from this patient. Furthermore, collagen produced no rise of cytosolic free calcium ([Ca2+]i) in fura2-loaded platelets. In contrast, thrombin caused TXB2 formation and an increase of [Ca2+]i in his platelets. These results suggest defective interaction between the platelets and collagen. The IgG from the ITP-patient induced irreversible aggregation in normal PRP, but caused no aggregation of the young man's platelets. Immunoblot studies showed that normal platelets had antigens with a molecular weight of 62 KDa under reducing conditions and of 57 KDa under nonreducing conditions. In contrast, the young man's platelets had no P62 band, although GPIa/IIa and thrombospondin were normally present. These results indicate that impaired collagen-induced aggregation in the patient's platelets was due to a deficiency of P62 and confirm that P62 may play a crucial role as a collagen receptor in platelet activation.
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PMID:Deficiency of P62, a putative collagen receptor, in platelets from a patient with defective collagen-induced platelet aggregation. 131 Nov 44

Integrin matrix receptors on glomerular epithelial cells (GEC) may play an important role in adhesion of GEC to the glomerular basement membrane (GBM) and in the maintenance of normal glomerular permeability. Therefore, the author determined the types of matrix receptors present on cultured rat GEC and examined their interactions with several components of the extracellular matrix. Beta 1 integrin matrix receptors were detected on all three glomerular cell types in rat kidney in vivo and at areas of cell-cell contact on cultured GEC. Glomerular epithelial cell adhesion to types I and IV collagen was slightly greater than to laminin and fibronectin. Adhesion to fibronectin was significantly inhibited by a synthetic peptide containing the RGD adhesion sequence. Immunoprecipitation of lysates of surface-iodinated GEC showed the presence of alpha 3 beta 1 integrin. Chromatography of lysates on immobilized collagen showed alpha 3 beta 1 integrin and a 70- to 75-kd protein band as the collagen receptors on GEC. Chromatography on the 120-kd cell-binding fragment of fibronectin disclosed only alpha 3 beta 1 as a specific fibronectin receptor. Antibody to the beta 1 integrin chain inhibited adhesion to laminin and collagen. These studies demonstrate that in vitro, as in vivo, GEC appear to express only alpha 3 beta 1 integrin. Furthermore, this matrix receptor is capable of mediating GEC adhesion to collagen, fibronectin, and laminin, components of the GBM, and presumably plays a similar role in promoting GEC adhesion to GBM in vivo.
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PMID:Characterization of glomerular epithelial cell matrix receptors. 132 40


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