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Jacob H. Rand - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Three Dimensional Relationships Among Components of Human Vascular Subendothelium by Stereo-Tilt Immunoelectron Microscopy
Journal of Histotechnology, 1998Co-Authors: Ronald E. Gordon, R. R. Uson, Robert W. Glanville, Huey-ju Kuo, Jacob H. RandAbstract:AbstractStereo-tilt immunoelectron microscopy offers a method for analyzing the inter-relationships among components of the Subendothelium at the 3 dimensional level. It has been demonstrated that von Willebrand factor (vWF) is important in the process of platelet adhesion following endothelial injury by serving as a bridge between constituents of the vascular Subendothelium and platelet membrane receptors. We had previously shown that type VI collagen microfibrils serve as a binding site for vWF in human vascular Subendothelium, and immunolabeling studies of vascular tissues by routine transmission electron microscopy showed apparent co-localization of the 2 proteins.We investigated the relationships among vWF, fibrillin and type VI collagen in human vascular Subendothelium with double labeling immunogold localization techniques in conjunction with stereo-tilt electron microscopy to examine the 3 dimensional ultrastructure of vWF-microfibril complexes.Our studies confirmed that vWF co-localizes with the ...
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Morphological relationships of von Willebrand factor, type VI collagen, and fibrillin in human vascular Subendothelium.
The American journal of pathology, 1996Co-Authors: Ronald E. Gordon, R. R. Uson, Robert W. Glanville, Huey-ju Kuo, Jacob H. RandAbstract:von Willebrand factor (vWF) plays an important role in the process of platelet adhesion after endothelial injury by serving as a bridge between constituents of the vascular Subendothelium and platelet membrane receptors. We previously presented evidence that type VI collagen microfibrils serve as a binding site for vWF in human vascular Subendothelium. However, others have proposed that vWF is not associated with type VI collagen but rather with the thicker elastin-associated microfibrils, which contain several proteins including fibrillin. We therefore investigated the relationships among vWF, type VI collagen, and fibrillin in human vascular Subendothelium by immunoelectron microscopy using single- and double-labeling immunogold localization techniques. In addition, we observed the three-dimensional ultrastructure of vWF-microfibril complexes by stereo paired micrographs and stereo viewer. We found that vWF co-localizes only with the type VI collagen microfibrils in Subendothelium but not with fibrillin microfibrils or striated collagen. The vWF is present in Subendothelium in the form of electron-dense aggregates having diameters varying between 65 and 80 nm that are closely associated with, and enmesh, the type VI collagen microfibrils and have structural similarities to intracellular Weibel-Palade bodies. The occasional co-localization of type VI collagen and fibrillin adjacent to internal elastic lamina was observed. These results are consistent with the hypothesis that type VI collagen, but not fibrillin-containing microfibrils, serves as a physiologically relevant binding site for vWF in the vascular Subendothelium, where the type VI collagen-vWF complex may play an important role modulating the hemostatic response to vascular injury.
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Co-localization of von Willebrand factor and type VI collagen in human vascular Subendothelium
The American journal of pathology, 1993Co-Authors: Jacob H. Rand, Barry J. Potter, R. R. Uson, Ronald E. GordonAbstract:The binding of von Willebrand factor (vWF) to Subendothelium constitutes an important initial step in the process of platelet adhesion to exposed Subendothelium following blood vessel injury. We previously demonstrated that vWF is present in human vascular Subendothelium and recently found that a 150 kd vWF-binding protein, which we extracted from Subendothelium, is type VI collagen. Although we have established that vWF and type VI collagen bind in vitro, it is not known whether these two proteins are associated in the vascular Subendothelium in situ. We, therefore, 1) investigated the morphological effects of our biochemical extraction procedure on human umbilical veins by scanning and transmission electron microscopy, 2) analyzed the subendothelial extract by immunofluorescence for the presence of vWF and collagens and by electron microscopy for morphological characteristics, and 3) localized vWF and type VI collagen in Subendothelium by immunofluorescence and by single- and double-label immunoelectron microscopic studies with protein A-conjugated gold particles. We found that the surface exposed following de-endothelialization is composed of microfibrils and contains very little fibrillar collagen. The Subendothelium is stripped after sodium dodecyl sulfate-urea extraction, and the extract itself contains immunoreactive vWF and type VI collagen but no immunoreactive type I or III fibrillar collagens. Immunofluorescence and immunoelectron microscopic studies showed that vWF and type VI collagen are both present in Subendothelium, where both co-localized to microfibrils. In conclusion, vWF that binds to type VI collagen in vitro, also co-localizes with type VI collagen in Subendothelium, where both are associated with microfibrils. Type VI collagen, therefore appears to serve as a biologically significant binding site for vWF in vivo and may thereby play a role in mediating platelet adhesion to exposed Subendothelium following vascular injury.
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150 kd von willebrand factor binding protein extracted from human vascular Subendothelium is type vi collagen
Journal of Clinical Investigation, 1991Co-Authors: Jacob H. Rand, N D Patel, E Schwartz, Shengli Zhou, Barry J. PotterAbstract:We have previously shown that von Willebrand factor (vWF), a glycoprotein which plays a critical role in the adhesion of platelets to injured blood vessels, is present within vascular Subendothelium. We investigated the identity of the subendothelial binding site(s) for vWF by examining vWF binding to subendothelial constituents and solubilized a 150-kD protein with SDS-urea that bound vWF. This protein had an amino-acid composition similar to that of the type VI collagen alpha-1/alpha-2 chains, was recognized by specific polyclonal antibodies against type VI collagen, and had a similar acidic isoelectric point. Furthermore, we found that purified type VI collagen also bound vWF. Thus, we have identified the extracted 150-kD protein as type VI collagen. This protein may play a significant role in the binding of vWF to vascular Subendothelium in vivo.
Ronald E. Gordon - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Three Dimensional Relationships Among Components of Human Vascular Subendothelium by Stereo-Tilt Immunoelectron Microscopy
Journal of Histotechnology, 1998Co-Authors: Ronald E. Gordon, R. R. Uson, Robert W. Glanville, Huey-ju Kuo, Jacob H. RandAbstract:AbstractStereo-tilt immunoelectron microscopy offers a method for analyzing the inter-relationships among components of the Subendothelium at the 3 dimensional level. It has been demonstrated that von Willebrand factor (vWF) is important in the process of platelet adhesion following endothelial injury by serving as a bridge between constituents of the vascular Subendothelium and platelet membrane receptors. We had previously shown that type VI collagen microfibrils serve as a binding site for vWF in human vascular Subendothelium, and immunolabeling studies of vascular tissues by routine transmission electron microscopy showed apparent co-localization of the 2 proteins.We investigated the relationships among vWF, fibrillin and type VI collagen in human vascular Subendothelium with double labeling immunogold localization techniques in conjunction with stereo-tilt electron microscopy to examine the 3 dimensional ultrastructure of vWF-microfibril complexes.Our studies confirmed that vWF co-localizes with the ...
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Morphological relationships of von Willebrand factor, type VI collagen, and fibrillin in human vascular Subendothelium.
The American journal of pathology, 1996Co-Authors: Ronald E. Gordon, R. R. Uson, Robert W. Glanville, Huey-ju Kuo, Jacob H. RandAbstract:von Willebrand factor (vWF) plays an important role in the process of platelet adhesion after endothelial injury by serving as a bridge between constituents of the vascular Subendothelium and platelet membrane receptors. We previously presented evidence that type VI collagen microfibrils serve as a binding site for vWF in human vascular Subendothelium. However, others have proposed that vWF is not associated with type VI collagen but rather with the thicker elastin-associated microfibrils, which contain several proteins including fibrillin. We therefore investigated the relationships among vWF, type VI collagen, and fibrillin in human vascular Subendothelium by immunoelectron microscopy using single- and double-labeling immunogold localization techniques. In addition, we observed the three-dimensional ultrastructure of vWF-microfibril complexes by stereo paired micrographs and stereo viewer. We found that vWF co-localizes only with the type VI collagen microfibrils in Subendothelium but not with fibrillin microfibrils or striated collagen. The vWF is present in Subendothelium in the form of electron-dense aggregates having diameters varying between 65 and 80 nm that are closely associated with, and enmesh, the type VI collagen microfibrils and have structural similarities to intracellular Weibel-Palade bodies. The occasional co-localization of type VI collagen and fibrillin adjacent to internal elastic lamina was observed. These results are consistent with the hypothesis that type VI collagen, but not fibrillin-containing microfibrils, serves as a physiologically relevant binding site for vWF in the vascular Subendothelium, where the type VI collagen-vWF complex may play an important role modulating the hemostatic response to vascular injury.
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Co-localization of von Willebrand factor and type VI collagen in human vascular Subendothelium
The American journal of pathology, 1993Co-Authors: Jacob H. Rand, Barry J. Potter, R. R. Uson, Ronald E. GordonAbstract:The binding of von Willebrand factor (vWF) to Subendothelium constitutes an important initial step in the process of platelet adhesion to exposed Subendothelium following blood vessel injury. We previously demonstrated that vWF is present in human vascular Subendothelium and recently found that a 150 kd vWF-binding protein, which we extracted from Subendothelium, is type VI collagen. Although we have established that vWF and type VI collagen bind in vitro, it is not known whether these two proteins are associated in the vascular Subendothelium in situ. We, therefore, 1) investigated the morphological effects of our biochemical extraction procedure on human umbilical veins by scanning and transmission electron microscopy, 2) analyzed the subendothelial extract by immunofluorescence for the presence of vWF and collagens and by electron microscopy for morphological characteristics, and 3) localized vWF and type VI collagen in Subendothelium by immunofluorescence and by single- and double-label immunoelectron microscopic studies with protein A-conjugated gold particles. We found that the surface exposed following de-endothelialization is composed of microfibrils and contains very little fibrillar collagen. The Subendothelium is stripped after sodium dodecyl sulfate-urea extraction, and the extract itself contains immunoreactive vWF and type VI collagen but no immunoreactive type I or III fibrillar collagens. Immunofluorescence and immunoelectron microscopic studies showed that vWF and type VI collagen are both present in Subendothelium, where both co-localized to microfibrils. In conclusion, vWF that binds to type VI collagen in vitro, also co-localizes with type VI collagen in Subendothelium, where both are associated with microfibrils. Type VI collagen, therefore appears to serve as a biologically significant binding site for vWF in vivo and may thereby play a role in mediating platelet adhesion to exposed Subendothelium following vascular injury.
Harvey J. Weiss - One of the best experts on this subject based on the ideXlab platform.
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Flow-related platelet deposition on Subendothelium.
Thrombosis and haemostasis, 1995Co-Authors: Harvey J. WeissAbstract:The deposition of platelets on Subendothelium is controlled both by flow factors that determine their transport to the surface through convective diffusion, and by the kinetics of their interactions with the surface. Red cells influence platelet transport by several mechanisms, and may also influence platelet reactivity. Platelets initially contact the surface through the binding of membrane GPIb to von Willebrand factor (vWf) that is present in the Subendothelium or deposited there from plasma. Platelet spreading on the surface is promoted by the binding of the arg 1744 gly 1745 asp 1746 (RGD) region of vWf (at high shear rates) to platelet GPIIb-IIIa. At high (arterial) shear rates, vWf binding to GPIIb-IIIa also promotes thrombus formation. At these shear rates, thrombin that is generated at the subendothelial surface is not involved in platelet adhesion or thrombus formation that occurs early in thrombogenesis, but is a major mediator of subsequent thrombus growth and/or stabilization.
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Further studies on the presence of functional tissue factor activity on the Subendothelium of normal human and rabbit arteries
Thrombosis research, 1994Co-Authors: Harvey J. Weiss, Vincent T. Turitto, Thomas J. Hoffmann, Yale NemersonAbstract:Although tissue factor (TF) activity has been observed on the subendothelial surface of rabbit aorta and human umbilical cord, immunofluorescent and in situ hybridization methods have failed repeatedly to demonstrate TF in the intima of human blood vessels. In the present study, TF activity on everted, de-endothelialized arteries was studied by two methods. One utilized a flow system and measured fibrin deposition and fibrinopeptide A formation. The other utilized a newly developed rotating probe system and measured the conversion of factor X to factor Xa in the presence of factor VIIa and Ca+2. The study attempted to control, or assess, the possibility that functional TF could have been exposed on the vessel surface by the procedures used to prepare the arterial segments. By both methods, TF activity was detected on the Subendothelium of rabbit aortae and human umbilical arteries, and was unaffected by the length of storage or by inclusion of actinomycin D in the storage buffer. TF activity was also observed in the Subendothelium of adult human ileo-colic, internal mammary, and renal arteries, studied by the rotating probe method. The latter may underestimate TF activity, as some of the factor Xa formed appears to bind to the subendothelial surface. TF activity (Xa formation) was detected on the luminal surface (Subendothelium) of non-everted arteries, but increased activity was observed after eversion of the vessel. The source of the subendothelial TF, and its presence in normal Subendothelium in vivo, requires further study. In addition, if any of the TF activity observed in this study was derived from injured endothelial or myointimal cells during preparation of the everted vessel segments, the techniques described could serve as a useful model for studying TF-induced thrombosis and factor Xa formation on injured blood vessels, and for evaluating the anti-thrombotic properties of TF-inhibitors.
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Evidence that the arg1744 gly1745 asp1746 sequence in the GPIIb-IIIa-binding domain of von Willebrand factor is involved in platelet adhesion and thrombus formation on Subendothelium.
The Journal of laboratory and clinical medicine, 1993Co-Authors: Harvey J. Weiss, T Hoffmann, Akira Yoshioka, Zaverio M. RuggeriAbstract:Previous studies have strongly suggested that the initial attachment (adhesion) of platelets to Subendothelium or collagen at high shear rates is mediated by the binding of von Willebrand factor (vWf) to platelet glycoprotein Ib (GPIb). The finding in the present study that incubating human umbilical artery Subendothelium with a monoclonal antibody to the GPIb binding site of vWf markedly inhibited platelet adhesion is fully consistent with this hypothesis. Platelet adhesion (and thrombus formation) also requires GPIIb-IIIa, and previous studies have suggested that the binding of vWf to GPIIb-IIIa may be involved in this process. To explore this further, we utilized two monoclonal antibodies (152B-20 and 152B-6) that recognize the arg1744 gly1745 asp1746 (RGD) sequence of vWf. These antibodies selectively inhibit vWf binding to GPIIb-IIIa and have no cross-reactivity with other RGD-containing proteins that can bind to GPIIb-IIIa. When added to citrated human blood, these antibodies (152B-20 in particular) inhibited platelet adhesion and thrombus formation on rabbit Subendothelium at a shear rate of 2600 sec-1 but not at 400 sec-1. The results of the study thus provide direct evidence that the binding of vWf to GPIIb-IIIa is important for platelet adhesion and thrombus formation on Subendothelium at high shear rates and that the arg1744 gly1745 asp1746 sequence in the mature vWf is involved in this process.
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Upstream thrombus growth impairs downstream thrombogenesis in non-anticoagulated blood: effect of procoagulant artery Subendothelium and non-procoagulant collagen.
Thrombosis and haemostasis, 1991Co-Authors: Kjell S. Sakariassen, Harvey J. Weiss, Hans R. BaumgartnerAbstract:In the present experiments we have investigated the influence of wall shear rate and axial position on platelet and fibrin deposition which results when flowing human non-anticoagulated blood is exposed to either non-procoagulant fibrillar collagen (human type III) or procoagulant Subendothelium (rabbit aorta). Platelet adhesion, thrombus volume and fibrin deposition were morphometrically evaluated at axial positions of 1 and 13 mm following perfusions for 5 min at shear rates of 100, 650 and 2,600 s-1. An axially-dependent decrease of platelet adhesion (34-57%, p less than 0.01-0.05) and thrombus volume (57-80%, p less than 0.05) was observed on collagen at all shear rates. On Subendothelium, an axially-dependent decrease was observed for platelet adhesion only at 100 s-1 (29%; p less than 0.01) and for thrombus volume at shear rates of 650 s-1 and above (49-58%, p less than 0.01). Deposition of fibrin on Subendothelium was axially decreased (16-42%, p less than 0.05) at all shear rates, while no significant axial differences were seen on collagen. However, substantially more fibrin was deposited on the Subendothelium (p less than 0.05), and the upstream platelet adhesion and thrombus volume were lower than on collagen (p less than 0.05) at 100 s-1 and 650 s-1. The axially-dependent phenomena on the two surfaces are consistent with the concept of rapid-growing upstream thrombi which deplete the blood layer streaming adjacent ot the surface of platelets, leading to decreased platelet deposition further downstream.(ABSTRACT TRUNCATED AT 250 WORDS)
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Further evidence that glycoprotein IIb-IIIa mediates platelet spreading on Subendothelium.
Thrombosis and haemostasis, 1991Co-Authors: Harvey J. Weiss, Vincet T TurittoAbstract:In order to explore further the mechanism by which glycoprotein GPIIb-IIIa promotes platelet vessel wall interaction, platelet adhesion to Subendothelium was studied in an annular chamber in which Subendothelium from rabbit aorta was exposed at a shear rate of 2,600 s-1 to blood from patients with thrombasthenia. Perfusions were conducted for each of 5 exposure times (1, 2, 3, 5 and 10 min), and the percent surface coverage of the vessel segment with platelets in the contact (C) and spread (S) stage was determined. Increased values of platelet contact (C) were obtained in thrombasthenia at all exposure times; this finding is consistent with a defect in platelet spreading, based on a previously described kinetic model of platelet attachment to Subendothelium. According to this model of attachment, increased values of platelet contact (C) at a single exposure time may be indicative of either a defect in spreading (S) or initial contact (C), but multiple exposures will result in increased contact only for defects which are related to defective platelet spreading (S). The results obtained over a broad range of exposure times provide more conclusive evidence that GPIIb-IIIa mediates platelet spreading than those previously obtained at single exposure times.
J E Sadler - One of the best experts on this subject based on the ideXlab platform.
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von Willebrand's factor and von Willebrand's disease.
Current opinion in hematology, 1994Co-Authors: T Matsushita, Z Dong, J E SadlerAbstract:von Willebrand's factor is required for platelet adhesion to Subendothelium, and for normal factor VIII survival in the circulation. These functions require the assembly of von Willebrand's factor into multimers that exhibit properly regulated binding to platelet glycoprotein lb. Recent studies suggest that the propeptide of von Willebrand's factor may catalyze multimer assembly and have identified new segments of von Willebrand's factor that appear to regulate its affinity for glycoprotein lb. Two segments of von Willebrand's factor have been found to interact with collagen type VI, which is a candidate binding site for von Willebrand's factor in the Subendothelium. Advances in the identification of mutations have prompted a reclassification of von Willebrand's disease. ABO antigens on von Willebrand's factor may impair the efficacy of plasma or recombinant von Willebrand's factor when administered to patients with incompatible ABO blood type.
R. R. Uson - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Three Dimensional Relationships Among Components of Human Vascular Subendothelium by Stereo-Tilt Immunoelectron Microscopy
Journal of Histotechnology, 1998Co-Authors: Ronald E. Gordon, R. R. Uson, Robert W. Glanville, Huey-ju Kuo, Jacob H. RandAbstract:AbstractStereo-tilt immunoelectron microscopy offers a method for analyzing the inter-relationships among components of the Subendothelium at the 3 dimensional level. It has been demonstrated that von Willebrand factor (vWF) is important in the process of platelet adhesion following endothelial injury by serving as a bridge between constituents of the vascular Subendothelium and platelet membrane receptors. We had previously shown that type VI collagen microfibrils serve as a binding site for vWF in human vascular Subendothelium, and immunolabeling studies of vascular tissues by routine transmission electron microscopy showed apparent co-localization of the 2 proteins.We investigated the relationships among vWF, fibrillin and type VI collagen in human vascular Subendothelium with double labeling immunogold localization techniques in conjunction with stereo-tilt electron microscopy to examine the 3 dimensional ultrastructure of vWF-microfibril complexes.Our studies confirmed that vWF co-localizes with the ...
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Morphological relationships of von Willebrand factor, type VI collagen, and fibrillin in human vascular Subendothelium.
The American journal of pathology, 1996Co-Authors: Ronald E. Gordon, R. R. Uson, Robert W. Glanville, Huey-ju Kuo, Jacob H. RandAbstract:von Willebrand factor (vWF) plays an important role in the process of platelet adhesion after endothelial injury by serving as a bridge between constituents of the vascular Subendothelium and platelet membrane receptors. We previously presented evidence that type VI collagen microfibrils serve as a binding site for vWF in human vascular Subendothelium. However, others have proposed that vWF is not associated with type VI collagen but rather with the thicker elastin-associated microfibrils, which contain several proteins including fibrillin. We therefore investigated the relationships among vWF, type VI collagen, and fibrillin in human vascular Subendothelium by immunoelectron microscopy using single- and double-labeling immunogold localization techniques. In addition, we observed the three-dimensional ultrastructure of vWF-microfibril complexes by stereo paired micrographs and stereo viewer. We found that vWF co-localizes only with the type VI collagen microfibrils in Subendothelium but not with fibrillin microfibrils or striated collagen. The vWF is present in Subendothelium in the form of electron-dense aggregates having diameters varying between 65 and 80 nm that are closely associated with, and enmesh, the type VI collagen microfibrils and have structural similarities to intracellular Weibel-Palade bodies. The occasional co-localization of type VI collagen and fibrillin adjacent to internal elastic lamina was observed. These results are consistent with the hypothesis that type VI collagen, but not fibrillin-containing microfibrils, serves as a physiologically relevant binding site for vWF in the vascular Subendothelium, where the type VI collagen-vWF complex may play an important role modulating the hemostatic response to vascular injury.
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Co-localization of von Willebrand factor and type VI collagen in human vascular Subendothelium
The American journal of pathology, 1993Co-Authors: Jacob H. Rand, Barry J. Potter, R. R. Uson, Ronald E. GordonAbstract:The binding of von Willebrand factor (vWF) to Subendothelium constitutes an important initial step in the process of platelet adhesion to exposed Subendothelium following blood vessel injury. We previously demonstrated that vWF is present in human vascular Subendothelium and recently found that a 150 kd vWF-binding protein, which we extracted from Subendothelium, is type VI collagen. Although we have established that vWF and type VI collagen bind in vitro, it is not known whether these two proteins are associated in the vascular Subendothelium in situ. We, therefore, 1) investigated the morphological effects of our biochemical extraction procedure on human umbilical veins by scanning and transmission electron microscopy, 2) analyzed the subendothelial extract by immunofluorescence for the presence of vWF and collagens and by electron microscopy for morphological characteristics, and 3) localized vWF and type VI collagen in Subendothelium by immunofluorescence and by single- and double-label immunoelectron microscopic studies with protein A-conjugated gold particles. We found that the surface exposed following de-endothelialization is composed of microfibrils and contains very little fibrillar collagen. The Subendothelium is stripped after sodium dodecyl sulfate-urea extraction, and the extract itself contains immunoreactive vWF and type VI collagen but no immunoreactive type I or III fibrillar collagens. Immunofluorescence and immunoelectron microscopic studies showed that vWF and type VI collagen are both present in Subendothelium, where both co-localized to microfibrils. In conclusion, vWF that binds to type VI collagen in vitro, also co-localizes with type VI collagen in Subendothelium, where both are associated with microfibrils. Type VI collagen, therefore appears to serve as a biologically significant binding site for vWF in vivo and may thereby play a role in mediating platelet adhesion to exposed Subendothelium following vascular injury.
