Shelley R. Marder

Human neutrophils contain subpopulations of specific granules exhibiting different sensitivities to changes in cytosolic free calcium

We examined the role of mobilization of intracellular calcium in the ability of human neutrophils to discharge specific granule constituents upon stimulation with the synthetic chemotactic factor, N-formyl-met-leu-phe. Extracellular calcium was not required for optimal secretion of the specific granule markers lactoferrin and vitamin B12-binding protein. Depletion and chelation of intracellular calcium, as well as reconstitution experiments, however, revealed different calcium requirements for stimulated secretion of these markers. N-formyl-met-leu-phe-induced secretion of vitamin B12-binding protein required half-maximal change in intracellular calcium of greater than 20 nM, while lactoferrin requirements were approximately 140 nM. Thus, it appears that cytosolic free calcium modulates fusion of subpopulations of specific granules which with the neutrophil plasma membrane.

Pulmonary embolic disease: radiographic appearances

Abstract This pictorial essay reviews the varied radiographic appearances of pulmonary embolism of plain radiographs, CT, and spiral CT including correlation with radionuclide imaging. Pitfalls in the diagnosis of pulmonary embolism by spiral CT are discussed.