5-carbon ring, bridged by two oxygens (a peroxide.) The derived prostaglandins contain a single, unsaturated 5-carbon ring. In prostacyclins, this ring is conjoined to another oxygen-containing ring. In thromboxanes the ring becomes a 6-member ring with one oxygen. Production of PGE2 in bacterial and viral infections appear to be stimulated by certain cytokines, e.g., interleukin-1. See also Prostaglandin Prostaglandin receptors Prostanoid receptors Essential fatty acid Isoprostane Prostacyclin References Prostaglandins Eicosanoids