Risk of Sprint Fidelis defibrillator lead failure is highly dependent on age.

Background: In 2007, Medtronic Sprint Fidelis defibrillator leads were taken off the market due to a high rate of lead failure. Current data do not allow for risk stratification of patients with regard to lead failure.

Aims: We sought to determine predictors of Sprint Fidelis lead failure.

H4 histamine receptor mediates optimal migration of mast cell precursors to CXCL12.

Background: CXCL12, a constitutive chemokine (ligand of CXCR4 and CXCR7), is expressed in the skin and airway epithelium and plays a significant role in allergic airway diseases. The pleiotropic effects of CXCL12 are enhanced by cofactors specific to the target cell.

Objective: We hypothesized that histamine, a major mediator of allergic reactions, could interact with CXCL12 to promote human mast cell (MC) migration.