Kinetics of dissociation of transient tethers. Representative graphs depicting the distribution of interaction times for more than 35 individual transient attachment events (known as tether bonds) that occurred between microspheres coated with VWF-A1 (about 30 molecules per square micrometer) and surface-immobilized platelets purified from healthy individuals (A) or 2 patients with PT-VWD (B-C). Dissociation rate constants were estimated at wall shear stresses of 0.5 to 2.0 dyne cm^-2; k_off is the negative slope of the linear regression through the experimental data.