Disease relevance of LOC507790

• Local delivery of human hemopexin fragment of MMP-2 and COOH-terminal fragment of platelet factor-4 significantly inhibited the growth of well-established malignant glioma in nude and BALB/C mice [1].
• BACKGROUND: Studies have demonstrated a high incidence of antibodies to heparin/platelet factor 4 complexes, the antigen in heparin-induced thrombocytopenia, in patients after cardiopulmonary bypass surgery [2].

High impact information on LOC507790

• Moreover, the kinetics and dose dependency of this release are similar to those observed for the release of platelet factor 4, and the release of both molecules is blocked by pretreating the platelets with prostaglandin E1 and theophylline [3].
• The observed effects were specific for TSP and were not observed with platelet factor 4, beta-thromboglobulin, or fibronectin [4].
• Degradation was inhibited to the same extent as binding by increasing concentrations of heparin, fucoidan, platelet factor 4, or whole blood serum [5].
• Heparin, fucoidan, chondroitin sulfate, platelet factor 4, beta-thromboglobulin, unlabeled TSP, and serum derived from whole blood all competed for binding of [125I]TSP [5].
• These megakaryocytes were stained with acetylcholine esterase, and expressed platelet glycoprotein (GP)Ib beta, GPIIIa, and platelet factor 4 by reverse transcription-polymerase chain reaction analysis [6].

Biological context of LOC507790

• Isolation and amino acid sequence of bovine platelet factor 4 [7].
• 1H-NMR spectroscopy has been used to assign and to characterize the two histidine C2H resonances of the heparin binding protein, bovine platelet factor 4 [8].
• At 37 degrees C, PF-4 was internalized by confluent monolayer of bovine aortic endothelial cells primarily through low-affinity adsorptive endocytosis [9].
• Sequence analysis of a corresponding 3,201-base-pair EcoRI fragment isolated from a human genomic library demonstrated the existence of a variant of platelet factor 4, designated PF4var1 [10].
• A short peptide domain of platelet factor 4 blocks angiogenic key events induced by FGF-2 [11].

Anatomical context of LOC507790

• Cloning and characterization of platelet factor 4 cDNA derived from a human erythroleukemic cell line [12].
• To examine the interactions of PF-4 with the GAGs present on endothelial cell surfaces, we incubated 125I-PF-4 with cell suspensions derived from confluent monolayers of cultured bovine aortic endothelium [9].
• Characterization of a neutrophil cell surface glycosaminoglycan that mediates binding of platelet factor 4 [13].
• Purified platelet factor IV (PF4) stimulated migration of pericytes but not of smooth muscle cells nor endothelial cells [14].
• Inhibition of mesangial cell proliferation by platelet factor 4 [15].

Associations of LOC507790 with chemical compounds

• Platelet factor 4 (PF4), which is released by platelets during coagulation, binds very tightly to negatively charged oligosaccharides such as heparin [16].
• Bovine platelet factor 4 was isolated by affinity chromatography using dextran sulfate Sepharose and purified by subsequent gel filtration [7].
• The bovine platelet factor 4 amino-terminal region, which contains two unique phenylalanine residues, is extended by 15 residues relative to human platelet factor 4 [7].
• This observation and the presence of His-38 within the belt of positively charged residues around the platelet factor 4 tetramer supports the model of the platelet factor 4-heparin complex in which the polysaccharide crosses over each of the 2 alpha-helices of the 2 dimers at right angles [8].
• PF4 did not cause release of the cytoplasmic enzyme lactate dehydrogenase which indicates that exocytosis of granule-containing lysosomal enzymes did not result from cytolysis [17].

Physical interactions of LOC507790

• Carboxyl-terminal heparin-binding fragments of platelet factor 4 retain the blocking effect on the receptor binding of basic fibroblast growth factor [18].

Other interactions of LOC507790

• Influence of platelet factor 4 on the neutralization of heparin by protamine [19].

Analytical, diagnostic and therapeutic context of LOC507790

• EXPERIMENTAL DESIGN: Polymeric microspheres made of poly(lactic-co-glycolic acid) (PLGA) were loaded with very low amounts of PEX and PF-4/CTF [20].
• A single local s.c. injection of PLGA microspheres loaded with low amounts of PEX or PF-4/CTF resulted in an 88% and 95% reduction in glioma tumor volume 30 days post-treatment [20].
• Thirty minutes later, kidneys were removed and tissue processed for light, immunofluorescence, and electron microscopy for the assessment of glomerular alterations and the localization of immune complexes (IgG and BSA), platelet factor 4, and platelet cationic proteins [21].
• Immunofluorescence and immunocytochemistry revealed prominent localization of platelet factor 4, platelet cationic proteins, IgG and BSA within peripheral capillary walls of glomeruli concomitant with a reduction in GPA [21].
• RESULTS: Data available on 98 patients, randomized to receive either bovine or porcine heparin, revealed no significant difference in patient positivity by serotonin release assay (12% in both groups) or by the heparin/platelet factor 4 enzyme-linked immunosorbent assay (29% with porcine and 35% with bovine heparin) postoperatively [2].

References