Modulation of platelet membrane function via exogenous lipid moiety exposure alters platelet responsiveness to shear.

Shear-induced platelet activation may cause life-threatening thrombosis, particularly in patients with mechanical support devices or coronary atherosclerosis. The majority of present anti-platelet agents target or interfere with biochemical, rather than physical mechanisms of platelet activation. Less data and understanding exists with regard to pharmacologic modulation of shear-mediated platelet activation. In this work, we hypothesized that modulating cell membrane properties, via alteration of membrane composition through addition of exogenous lipid moieties, would alter platelet responsiveness to shear. Here we tested fatty acids, lecithin and cholesterol as additive lipid compounds. We demonstrated that incorporation of fatty acids (DHA/EPA) or lecithin into the platelet membrane triggered enhanced sensitivity of platelets to shear-mediated activation. On the other hand, cholesterol incorporation provides significant protection, limiting the effect of shear on platelet activation. These findings provide valuable insight for the development of therapeutic strategies that can modulate shear-mediated platelet activation.

Visual and Haptic influences on memory: age differences in recall.

Older (age 60-75) and younger adults (age 20-35) participated in a within-subject experiment. All participants were given four lists of 17 items, a recall test followed each list. Each participant was given a separate list under each of the following conditions, at the rate of 1 item every 10 s. (1) control: list of nouns; (2) visual-only: visually shown objects; (3) visual-and-haptic: given objects to hold and visually examine; (4) haptic-only: blindfolded, given objects to hold. A final surprise recall test was given of all items presented in the study. Data indicated that younger adults recalled more than older adults under all conditions. However, both age groups had the highest recall under the haptic conditions.