Biomedical subjects

P C Isakson

Publications and source records attributed to P C Isakson.

95 records · Page 6Linked to original sources

PubMed1975

Relationship between oxygen tension, coronary vasodilation and prostaglandin biosynthesis in the isolated rabbit heart.

In isolated perfused rabbit hearts, coronary vasodilation, produced by reduced oxygen tension seems to be independent of myocardial prostaglandin biosynthesis. a) Anoxia (N2: CO2 95: 5 %) produced coronary vasodilation without causing prostaglandin-like substance (PLS) biosynthesis and release; b) the decrease in coronary resistance during hypoxia (N2:02:CO2 - 80:15:5 %) was sustained during myocardial perfusion with the low oxygen media despite the transitory nature of its PLS release; and c) indomathacin, which abolished basal or ADP stimulated myocardial PLS release, did not abolish the coronary vasodilation produced by ischemia, hypoxia, or anoxia.

Animals↗

PubMed1975

Mechanism and modification of bradykinin-induced coronary vasodilation.

In isolated perfused rabbit hearts, bradykinin produced a concentration-dependent decrease in coronary resistance directly associated with biosynthesis and release of prostaglandin-E-like substance. An inhibitor of bradykinin destruction (the nonapeptide SQ-20881) markedly enhanced both the coronary vasodilation and release of prostaglandin-E-like substance produced by cardiac injection of bradykinin. Indomethacin inhibited both the myocardial prostaglandin biosynthesis and the decrease in coronary resistance induced by bradykinin. The demonstration that bradykinin is a potent stimulator of prostaglandin biosynthesis in the heart has implications as to the cause of the afferent cardiovascular reflexes and pain in myocardial infarction and angina pectoris.

Animals↗

PubMedDate not supplied

Celecoxib versus diclofenac in long-term management of rheumatoid arthritis: randomised double-blind comparison.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclo-oxygenase (COX), which leads to suppression of COX-1-mediated production of gastrointestinal-protective prostaglandins. Gastrointestinal injury is a common outcome. We compared the efficacy, safety, and tolerability of long-term therapy with celecoxib, a COX-1 sparing inhibitor of COX-2, with diclofenac, a non-specific COX inhibitor. METHODS: 655 patients with adult-onset rheumatoid arthritis of at least 6 months' duration were randomly assigned oral celecoxib 200 mg twice daily or diclofenac SR 75 mg twice daily for 24 weeks. Anti-inflammatory and analgesic activity and tolerability were assessed at baseline, every 4 weeks, and at week 24. We assessed gastrointestinal safety by upper-gastrointestinal endoscopy within 7 days of the last treatment dose at centres where the procedure was available. Analysis was by intention-to-treat. FINDINGS: 430 patients underwent endoscopy (celecoxib n=212, diclofenac n=218). The two drugs were similar in management of rheumatoid arthritis pain and inflammation. Gastroduodenal ulcers were detected endoscopically in 33 (15%) patients treated with diclofenac and in eight (4%) in the celecoxib group (p<0.001). The rate of withdrawal for any gastrointestinal-related adverse event, most commonly abdominal pain, diarrhoea, and dyspepsia, was nearly three times higher in the diclofenac-treated group than in the celecoxib group (16 vs 6%; p<0.001). INTERPRETATION: Celecoxib showed sustained anti-inflammatory and analgesic activity similar to diclofenac, with a lower frequency of upper gastrointestinal ulceration or gastrointestinal adverse events, and tolerability was better.

Analysis of Variance↗

PubMedDate not supplied

Structural basis for selective inhibition of cyclooxygenase-2 by anti-inflammatory agents.

Prostaglandins and glucocorticoids are potent mediators of inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) exert their effects by inhibition of prostaglandin production. The pharmacological target of NSAIDs is cyclooxygenase (COX, also known as PGH synthase), which catalyses the first committed step in arachidonic-acid metabolism. Two isoforms of the membrane protein COX are known: COX-1, which is constitutively expressed in most tissues, is responsible for the physiological production of prostaglandins; and COX-2, which is induced by cytokines, mitogens and endotoxins in inflammatory cells, is responsible for the elevated production of prostaglandins during inflammation. The structure of ovine COX-1 complexed with several NSAIDs has been determined. Here we report the structures of unliganded murine COX-2 and complexes with flurbiprofen, indomethacin and SC-558, a selective COX-2 inhibitor, determined at 3.0 to 2.5 A resolution. These structures explain the structural basis for the selective inhibition of COX-2, and demonstrate some of the conformational changes associated with time-dependent inhibition.

Animals↗

PubMedDate not supplied

Cox-2-specific inhibitors: definition of a new therapeutic concept.

Nonsteroidal anti-inflammatory drugs have been a mainstay in the treatment of inflammatory diseases such as rheumatoid arthritis. However, these agents can result in severe and occasionally life-threatening adverse effects that can limit therapeutic benefit. Progress toward safer anti-inflammatory therapy was aided by the discovery that cyclooxygenase (COX) exists as two isozymes, COX-1 and COX-2. Both isozymes form prostaglandins that support physiologic functions; however, the formation of proinflammatory prostaglandins is catalyzed by COX-2. Inhibition of COX-2 accounts for the anti-inflammatory and analgesic action of NSAIDs; however, concurrent inhibition of COX-1 inhibits prostaglandin-dependent mechanisms such as gastroduodenal mucosal defense and platelet aggregation. This inhibition is the basis of the gastrointestinal toxicity and bleeding characteristic of these drugs. These findings led to the hypothesis that agents that selectively inhibit COX-2 would possess anti-inflammatory and analgesic action but would spare COX-1, thereby avoiding adverse effects in the gastrointestinal tract and platelets. Selective COX-2 inhibitors are now available. The novelty of these agents has raised questions in the medical community as to what constitutes selectivity for COX-2. This review outlines the criteria that must be met to characterize a compound as COX-2-specific. Clinical evidence of clear improvement in gastrointestinal tolerability and safety must be demonstrated in addition to complementary evidence of COX-2 selectivity obtained from enzyme, biochemical, and clinical pharmacology evaluations.

Anti-Inflammatory Agents, Non-Steroidal↗