Induction of an acetaminophen-sensitive cyclooxygenase with reduced sensitivity to nonsteroid antiinflammatory drugs.

The transformed monocyte/macrophage cell line J774.2 undergoes apoptosis when treated for 48 h with competitive inhibitors of cyclooxygenase (COX) isoenzymes 1 and 2. Many of these nonsteroid antiinflammatory drugs (NSAIDs), but in particular diclofenac, induce during this time period a COX activity that coincides with a robust induction of COX-2 protein. Induction of this activity requires high, apoptosis-inducing concentrations of diclofenac (>100 microM). Prolonged treatment of J774.2 cells with lower doses of diclofenac inhibits COX activity, indicating that diclofenac is a time-dependent, pseudoirreversible inhibitor of COX-2. It is difficult to wash out the inhibition. However, the activity evoked by high concentrations of diclofenac has a profoundly distinct COX active site that allows diclofenac, its inducer, to be washed readily from its active site. The diclofenac-induced activity also has the unusual property of being more sensitive to inhibition by acetaminophen (IC50 = 0.1-1.0 mM) than COX-2 induced with bacterial lipopolysaccharide. Moreover, relative to COX-1 or COX-2, diclofenac-induced enzyme activity shows significantly reduced sensitivity to inhibition by diclofenac or other competitively acting nonsteroid antiinflammatory drugs (NSAIDs) and the enzyme activity is insensitive to aspirin. If the robust induction of COX-2 observed is responsible for diclofenac-induced COX enzyme activity, it is clear that COX-2 can, therefore, exist in two catalytically active states. A luciferase reporter-construct that contains part of the COX-2 structure and binds into the membrane showed that chronic diclofenac treatment of fibroblasts results in marked mobilization of the fusion protein. Such a mobilization could result in enzymatically distinct COX-2 populations in response to chronic diclofenac treatment.

Fun in the sun: an outdoor program in a health care setting.

The Children's Hospital of Eastern Ontario in Ottawa, Ontario, has had a supervised playground program for the past 6 years, which is available to inpatients, outpatients, and their visitors. This paper describes playground staff and volunteer prerequisites, the role of interdisciplinary involvement, equipment and materials, factors to consider when planning outdoor activities, and the activities found to be most useful. The authors' purpose is not to give the recipe for an ideal playground program, but rather to stimulate interest in the desirability of playground programs in health care settings through the description of one such facility.