scholarly journals Human megakaryocytes. II. Expression of platelet proteins in early marrow megakaryocytes.

1981 ◽  
Vol 154 (1) ◽  
pp. 88-100 ◽  
Author(s):  
E M Rabellino ◽  
R B Levene ◽  
L L Leung ◽  
R L Nachman
Keyword(s):  
Factor Viii ◽  
Fc Receptors ◽  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Ia Antigen ◽  
Plasma Factor ◽  
Factor Viii Antigen ◽  
Megakaryocyte Differentiation ◽  
Marrow Cells ◽  
Platelet Proteins

Analysis of various platelet proteins by immunofluorescence demonstrated that platelet glycoproteins Ib, IIb, and IIIa, as well as plasma factor VIII antigen (factor VIII:AGN), platelet factor 4, and fibronectin are present in the vast majority of morphologically recognizable megakaryocytes. In addition, a small number of lymphoid-like mononuclear marrow cells, representing approximately 1.4--2.9/10(4) marrow cells, was found to express the same platelet proteins. This population of early marrow megakaryocytes is analogous to small acetylcholinesterase-positive rat and mouse marrow cells. Fc receptors for IgG were expressed in all megakaryocytes and megakaryocyte precursors, whereas the Ia antigen was detected only on a proportion of mature megakaryocytes and not on only early or precursor megakaryocytes. Platelet glycoproteins Ib, IIb, and IIIa, as well as factor VIII:AGN, and platelet factor 4 were established as distinct markers for marrow megakaryocytes and may be helpful for identifying megakaryocytic cells as well as for monitoring events of megakaryocyte differentiation.

scholarly journals Subcellular platelet factor VIII antigen and von Willebrand factor.

1975 ◽  
Vol 141 (5) ◽  
pp. 1101-1113 ◽  
Author(s):  
R L Nachman ◽  
E A Jaffe
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Human Platelets ◽  
Factor Vii ◽  
Platelet Factor ◽  
Plasma Factor ◽  
Factor Viii Antigen ◽  
Von Willebrand ◽  
Willebrand Factor

Subcellular membrane and granule fractions derived from human platelets contain factor VIIII antigen and von Willebrand factor activity but not factor VII procoagulant activity. Circulating platelets constitute a significant reservoir of plasma factor VIII antigen, containing approximately 15% of the amount of factor VIII antigen present in platelet-poor plasma. The antibiotic ristocetin, which aggregates human platelets in the presence of von Willebrand factor, nonspecifically precipitates platelet membrane factor VIII antigen. Thus normal platelets contain surface-bound as well as internally stored von Willebrand factor, a protein synthesized by endothelial cells which is necessary for normal platelet function in vivo.

Live Attenuated Salmonella Carrying Platelet Factor 4 cDNAs as Radioprotection and Anti-Tumor Angiogenesis Agents.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3178-3178
Author(s):  
Zhong Chao Han ◽  
Bin Liu ◽  
Lihua Zhao
Keyword(s):  
Gene Therapy ◽  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Tumor Regression ◽  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Delivery Vector ◽  
Total Body ◽  
Marrow Cells

Abstract In cancer therapy, specific radioprotection of normal tissue and antiangiogenesis are the ways to increase the therapeutic gain. Here we describe a novel gene therapy, which uses attenuated salmonella SL3261 as oral vectors carrying with cDNA of platelet factor 4 (PF4) or that of a truncated PF4. After oral administrations of attenuated salmonella carrying with cDNA of PF4 or truncated PF4, the survival rate of mice which received sublethal total body irradiation was improved by 50%, In comparison with the control mice, the bone marrow cells obtained from the mice of experimental group increased (13.2±8.3, 15.7±1.5 vs 4.1 ± 2.0 P<0.05) at day 7 after TBI, and the number of HPP-CFC of bone marrow cells also increased significantly (15.7±9, 11.7±5 vs 4.3±4.1 P<0.05) at day 7, suggesting a stimulating effect of PF4 on hematopoietic recovery. This gene therapy also caused significant tumor regression. The microvessel density (MVD) of tumors was significantly decreased in the group of treated mice compared to controls (4.25±0.96, 4.08±0.56 vs 11±0.83 P<0.05). Analysis TUNEL kit revealed an increase in the number of apoptosis cells in tumors of mice treated by SL3261 carrying with cDNA of PF4 or a truncated PF4. GFP expression and gene integration were detected in the liver, kidney, spleens, intestine, peripheral blood, bone marrow and tumors samples of the SL3261 treated mice, and the expression of GFP was higher in tumors than that in other tissues. These data demonstrate for the first time a dual biological function of PF4 against tumor growth and radiation injury. These results also demonstrate that attenuated salmonella can be used in vivo as a DNA delivery vector

Rabbit Antibodies Against the Procoagulant Activity (VIII:C) of Human Factor VIII

1981 ◽  
Vol 46 (04) ◽  
pp. 699-705 ◽  
Author(s):  
T H Tran ◽  
G A Marbet ◽  
F Duckert
Keyword(s):  
Factor Viii ◽  
Human Factor ◽  
Gel Filtration ◽  
Procoagulant Activity ◽  
Solid Matrix ◽  
Factor Viii Activity ◽  
Physiological Conditions ◽  
Human Factor Viii ◽  
Plasma Factor ◽  
Factor Viii Antigen

SummaryThe procoagulant activity VIII:C was separated from factor VIII antigen (VIIIR:Ag) by gel filtration in the presence of 0.25 mol/l calcium chloride. Antibodies (anti-VIII:C) were obtained by immunization of rabbits with VIII:C. The last step of the purification procedure of antibodies consists of an adsorption on VIIIR:Ag-Sepharose 2 BCL as immunoadsorbent to remove contaminating traces of antibodies against VIIIR:Ag. The anti- VIII:C titer remains unchanged during this adsorption (29 Bethesda units per mg). In solution, anti-VIII:C neutralies factor VIII activity (in plasma, cryoprecipitate or in purified form) and the fragment VIII:C without reacting with VIIIR:Ag. Once immobilized on a solid matrix, i.e.2% agarose, it loses over 95% of its inhibitory capacity. The immobilized anti-VIIIR:Ag binds stoichiometrically the antigen and the activity of plasma factor VIII. These results together suggest that factor VIII is composed of 2 different entities, but undissociated under physiological conditions. Immunophysical analyses as a function of pH and temperature of anti-VIII:C and its complex with factor VIII show properties similar to those of homologous antibodies. The antigen determinants of VIII:C (VIII:CAg) are destroyed at low pHs or high temperatures, and VIII:C can no more form a complex with anti-VIII:C. Purified anti-VIII:C is also used in a two-stage assay to detect VIII:CAg or cross-reacting material in some severe haemophiliacs.

Nomenclature of Secreted Platelet Proteins – Report of the Working Party on Secreted Platelet Proteins of the Subcommittee on Platelets

1985 ◽  
Vol 53 (02) ◽  
pp. 282-284 ◽  
Author(s):  
Karen L Kaplan ◽  
Stefan Niewiarowski
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Cellulose Acetate ◽  
Working Party ◽  
Platelet Factor 4 ◽  
Cellulose Acetate Electrophoresis ◽  
Platelet Factor ◽  
Amino Terminal ◽  
Platelet Proteins

SummaryStandard nomenclature for a number of secreted platelet proteins was agreed upon by The Working Party on Secreted Platelet Proteins of the Subcommittee on Platelets. Platelet factor 4 will continue to be used for the molecule with high heparin affinity, subunit molecular weight of 7780, and the described amino acid sequence. β-Thromboglobulin will be used to designate β-Thromboglobulin (81 amino acids/subunit, β-mobility on cellulose-acetate electrophoresis, pI 7), low-affinity platelet factor 4 (85 amino acids/subunit, y-mobility on cellulose-acetate electrophoresis, pI 8), and platelet basic protein (94 amino acids/ subunit, pI 10) when these are measured immunologically in plasma, but that thromboglobulin with a superscript designation of the pI should be used when assays are conducted on samples after isoelectric focusing, and a subscript amino-terminal amino acid can be added when a purified protein is described. Thrombospondin will continue to be the designation for the high molecular weight trimer that has previously been called thrombospondin or glycoprotein G. Platelet derived growth factor will be used for the group of closely related proteins of molecular weight about 30,000 and isoelectric point about 10.

scholarly journals Immunoelectron microscopic localization of platelet factor 4 and fibrinogen in the granules of human platelets.

1983 ◽  
Vol 31 (7) ◽  
pp. 905-910 ◽  
Author(s):  
T D Pham ◽  
K L Kaplan ◽  
V P Butler
Keyword(s):  
Human Platelets ◽  
Platelet Factor 4 ◽  
Water Soluble ◽  
Antigenic Determinants ◽  
Storage Site ◽  
Human Fibrinogen ◽  
Platelet Factor ◽  
Thin Sections ◽  
Fab Fragments ◽  
Platelet Proteins

To determine the storage site of platelet fibrinogen and of platelet factor 4 (PF4) in human platelets by immunoelectron microscopic techniques, washed human platelets were briefly exposed to Karnovsky's fixative and embedded in water-soluble Durcupan. Thin sections of platelets were exposed to Fab fragments of rabbit anti-human fibrinogen or of goat anti-human PF4, followed by a peroxidase conjugate of Fab fragments of antibodies to rabbit immunoglobulin (Ig) G or to goat IgG. The technique enabled preservation of the antigenic determinants of the platelet proteins, accessibility of Fab fragments to the platelet proteins, and maintenance of the ultrastructural integrity of the platelets. Using this approach, it was directly demonstrated that platelet fibrinogen and PF4 are stored in the alpha-granules of human platelets.

Altered bioavailability of platelet-derived factor VIII during thrombocytosis reverses phenotypic efficacy in haemophilic mice

2008 ◽  
Vol 100 (12) ◽  
pp. 1111-1122 ◽  
Author(s):  
Andrea L. Damon ◽  
Lesley E. Scudder ◽  
Dmitri V. Gnatenko ◽  
Varsha Sitaraman ◽  
Patrick Hearing ◽  
...  
Keyword(s):  
Factor Viii ◽  
Transgenic Mouse ◽  
Comparative Studies ◽  
Amyloid Β ◽  
Platelet Factor 4 ◽  
Precursor Protein ◽  
Haemophilia A ◽  
Platelet Factor ◽  
Thrombin Cleavage ◽  
Viable Approach

SummaryEctopic delivery of factor VIII (FVIII) to megakaryocytes (Mk) represents a viable approach for localized tenase generation by concentrating the FVIIIa/FIXa enzymecofactor complex onto activated platelet membranes. We utilized a core rat platelet factor 4 (PF4) promoter for Mk/platelet-restricted expression of human B-domain-deleted (hBDD) FVIII within the background of a haemophilia A mouse (rPF4/hBDD/FVIII-/-). Platelets from rPF4/hBDD/FVIII-/- mice contained ∼122 mU FVIII:C/1x109 platelets/ml with no detectable plasmatic FVIII:C,and with no effect on α-granule-derived platelet factorV/Va function.Paired tenase assays (± thrombin) confirmed that platelet (pt) FVIII (unlike platelet FV) required thrombin cleavage for complete activation. rPF4/hBDD/FVIII-/- mice exposed to a thrombocytotic stimulus (thrombopoietin, TPO) demonstrated a statistically-significant 66% reduction in molar ptFVIII activity with a non-significant reduction in total ptFVIII biomass. Decreased molar ptFVIII concentration correlated with loss of phenotypic correction as evaluated using a haemostatic tail-snip assay. Comparative studies using a transgenic mouse expressing human amyloid-β-precursor protein (hAβPP) from the rPF4 promoter confirmed diminished hAβPP expression without affecting endogenous α-granule PF4, establishing generalizability of these observations.While Mk/plateletreleased ptFVIII (unlike pFV) is proteolytically inactive, we also conclude that thrombocytotic stimuli negatively affect ptFVIII bioavailability and phenotypic efficacy, results which correlate best with molar ptFVIII concentration, and not systemically available ptFVIII.

scholarly journals Human platelet surface binding of endogenous secreted factor VIII-von Willebrand factor and platelet factor 4

Blood ◽  
1982 ◽  
Vol 59 (1) ◽  
pp. 194-197 ◽  
Author(s):  
JN George ◽  
AR Onofre
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Membrane Surface ◽  
Platelet Factor 4 ◽  
Secreted Proteins ◽  
Surface Binding ◽  
Platelet Factor ◽  
Platelet Surface ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Washed human platelets in buffers containing either 2 mM Ca++ or 4 mM EDTA were stimulated by human alpha-thrombin to induce secretion. The binding of two endogenous secreted proteins, factor-VIII-related protein (VIII-R) (von Willebrand factor) and platelet factor 4, was measured by reacting thrombin-treated and control platelets with specific antibodies to these proteins, then quantifying antibody binding with 125I-staphylococcal protein A. Both of these granule proteins were associated with the platelet membrane surface by a calcium-dependent mechanism after thrombin-induced secretion. This ability to bind endogenous secreted proteins to the plasma membrane surface may provide a mechanism by which the platelet can concentrate and organize its secreted proteins for subsequent physiologic reactions.

Sign in / Sign up

Export Citation Format

Share Document