Effect of a cyclooxygenase-2 inhibitor on postexercise muscle protein synthesis in humans.

Nonselective blockade of the cyclooxygenase (COX) enzymes in skeletal muscle eliminates the normal increase in muscle protein synthesis following resistance exercise. The current study tested the hypothesis that this COX-mediated increase in postexercise muscle protein synthesis is regulated specifically by the COX-2 isoform. Sixteen males (23 +/- 1 yr) were randomly assigned to one of two groups that received three doses of either a selective COX-2 inhibitor (celecoxib; 200 mg/dose, 600 mg total) or a placebo in double-blind fashion during the 24 h following a single bout of knee extensor resistance exercise. At rest and 24 h postexercise, skeletal muscle protein fractional synthesis rate (FSR) was measured using a primed constant infusion of [(2)H(5)]phenylalanine coupled with muscle biopsies of the vastus lateralis, and measurements were made of mRNA and protein expression of COX-1 and COX-2. Mixed muscle protein FSR in response to exercise (P < 0.05) was not suppressed by the COX-2 inhibitor (0.056 +/- 0.004 to 0.108 +/- 0.014%/h) compared with placebo (0.074 +/- 0.004 to 0.091 +/- 0.005%/h), nor was there any difference (P > 0.05) between the placebo and COX-2 inhibitor postexercise when controlling for resting FSR. The COX-2 inhibitor did not influence COX-1 mRNA, COX-1 protein, or COX-2 protein levels, whereas it did increase (P < 0.05) COX-2 mRNA (3.0 +/- 0.9-fold) compared with placebo (1.3 +/- 0.3-fold). It appears that the elimination of the postexercise muscle protein synthesis response by nonselective COX inhibitors is not solely due to COX-2 isoform blockade. Furthermore, the current data suggest that the COX-1 enzyme is likely the main isoform responsible for the COX-mediated increase in muscle protein synthesis following resistance exercise in humans.

Open label study to assess infliximab safety and timing of onset of clinical benefit among patients with rheumatoid arthritis.

OBJECTIVE: To assess the timing of onset of clinical benefit following the initial infusion of infliximab and to obtain additional safety experience of infliximab when given in an office setting to patients with rheumatoid arthritis (RA). In addition, the safety of reducing the infusion time from 2 hours to 1 hour was evaluated. METHODS: Patients (n = 553) with active RA despite receiving methotrexate (MTX) were treated with infliximab 3 mg/kg given over 2 h at baseline (Week 0), and Weeks 2, 6, and 14 in this multicenter open-label trial. Patients continued to receive a stable dose of MTX (> or = 7.5 mg/wk). At selected sites, patients tolerating the first 4 infusions were eligible to receive 2 additional infusions at twice the usual infusion rate (given over 1 h). Patients returned for efficacy assessments at 48 h following the initial infusion and several times throughout study participation. RESULTS: By 48 h following the first infusion, significant (p < 0.001) improvements were observed in duration of morning stiffness (34% mean improvement), physician's global disease assessment scores (30%), patient's global disease assessment scores (25%), and patient's pain assessment scores (30%). By Week 16, 52 to 63% mean improvements in these efficacy variables were observed (p < 0.001), the significant improvement was maintained through the end of study participation in the subset of patients who received the additional 1 h infliximab infusions. Through 16 weeks, 10% (54/553) of patients reported an adverse event associated with at least 1 of the 4 infusion procedures; the majority were mild and transient in nature. In the subset of 197 patients who received 2 additional infusions over 1 h, no increase in the frequency or severity of infusion-related adverse events was observed compared to the 2 h infusion. CONCLUSION: Infliximab administered to patients with RA in an outpatient setting resulted in significant clinical improvement within 48 h that was sustained with additional infusions. Approximately 10% of patients experienced an infusion reaction, highlighting the need for direct supervision over patient treatment. Patients who tolerated infliximab infusions given over 2 h also tolerated a 1 h infusion.