A tripeptide mimetic of von Willebrand factor residues 981-983 enhances platelet adhesion to fibrinogen by signaling through integrin alpha(IIb)beta3.

Background: RGD is a major recognition sequence for ligands of platelet alpha(IIb)beta3.

Objective And Methods: To identify potential binding sites for alpha(IIb)beta3 apart from RGD, we screened phage display libraries by blocking the enrichment of RGD-containing phages with a GRGDS peptide and identified a novel integrin recognition tripeptide sequence, VPW.

Results: Platelets adhered to an immobilized cyclic VPW containing peptide in a alpha(IIb)beta3-dependent manner; platelets and alpha(IIb)beta3-expressing CHO cells adhered faster to immobilized alpha(IIb)beta3-ligands in the presence of soluble VPW.

Involvement of the beta3 E749ATSTFTN756 region in stabilizing integrin alphaIIbbeta3-ligand interaction.

Platelet integrin alphaIIbbeta3 must be activated via intracellular mechanisms before it binds soluble ligands, and it is thought to be activated at its extracellular site by surface-bound ligands. Integrin activation is associated with rearrangement of the cytoskeleton and phosphorylation of proteins that become localized in focal contacts. In these processes, the cytoplasmic tail of the beta-subunit plays a central role.

Cytoplasmic regions of the beta3 subunit of integrin alphaIIbbeta3 involved in platelet adhesion on fibrinogen under flow conditions.

Platelet adhesion to surface-bound fibrinogen depends on integrin alphaIIbbeta3. In the present study, we investigated the role of the regions 749EATSTFT756N and 755TNITYRG762T of the beta3 cytoplasmic tail in the regulation of platelet adhesion under flow conditions, by introducing peptide mimetics in platelets. Introduction of peptide EATSTFTN (E-N) increased surface coverage by 35%, an effect caused by 25% more adhesion.

Characterization of the screwworm flies Cochliomyia hominivorax and Cochliomyia macellaria by PCR-RFLP of mitochondrial DNA.

The primary screwworm fly Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) is one of the most important insect pests of livestock in neotropical regions, whereas Cochliomyia macellaria (Fabricius) (Diptera: Calliphoridae), the secondary screwworm, is of medical and sanitary importance because of its role in the dissemination of pathogens. These two species share morphological similarities and both may occur in the same myiasis, but in different developmental stages. In this work, the usefulness of PCR-RFLP (polymerase chain reaction - restriction fragment length polymorphism) of mitochondrial DNA (mtDNA) for the unambiguous identification of C.