Showing papers on "Canine Mastocytoma published in 1993"

In vitro histamine release induced by magnetic resonance imaging and iodinated contrast media

Abstract: Rationale and objectives To investigate the mechanism of anaphylactoid reactions to contrast media, in vitro histamine release induced by magnetic resonance imaging, and iodinated contrast agents was examined in a dog mastocytoma cell line. Methods Two gadolinium (Gd)-based magnetic resonance contrast agents, Gd diethylenetriamine pentaacetic acid (Gd-DTPA), dimeglumine, and Gd-bismorpholide, and two iodinated contrast agents, diatrizoate meglumine and iohexol, were incubated with histamine-containing canine mastocytoma cells. Release of histamine into the supernatant was determined at various contrast-medium concentrations after incubation at 37 degrees C for 30 minutes. Results Iodinated and Gd-based contrast agents caused release of histamine from mastocytoma cells at similar concentrations (50-150 mM). Mannitol, an osmotic stimulus, caused release of histamine only at concentrations greater than 1,000 mM. Conclusions Histamine release from canine mastocytoma cells does not appear to be solely due to osmotic effects, but results from direct stimulation by contrast media. For all agents examined, the concentration at which in vitro histamine release occurs far exceeds the serum contrast media concentration expected in routine clinical application. Direct release of histamine from mast cells does not completely explain the pathogenesis of idiosyncratic anaphylactoid responses to contrast media.

Mitogen-inducible prostaglandin G/H synthase is expressed in canine mastocytoma cells.

Abstract: A mitogen-inducible prostaglandin G/H synthase (PGHS-2 or cyclooxygenase-2) has recently been cloned from chicken and mouse fibroblasts. This protein is distinct from classic prostaglandin G/H synthase (PGHS-1 or cyclooxygenase-1) but has a similar enzymatic activity. Because PGHS-1 is a rate-limiting enzyme in the synthesis of prostaglandins, PGHS-2 may also play an important role in prostaglandin production. To examine whether PGHS-2 is induced by phorbol ester in mast cells, we studied mRNA expression of PGHS-2 and also measured prostaglandin D2 (PGD2) production when canine mastocytoma cells were incubated with phorbol myristate acetate (PMA). PGHS-2 mRNA was induced by PMA, with a maximal induction after 4 h of incubation with 10 nM PMA. There was concentration-dependent production of PGD2 after incubation with PMA. In contrast, PGHS-1 mRNA was expressed in resting cells, and the expression of PGHS-1 mRNA was down-regulated by PMA. Dexamethasone inhibited PMA-induced mRNA expression of PGHS-2 and PGD...