Targeted disruption of the endothelin-B-receptor gene attenuates inflammatory nociception and cutaneous inflammation in mice.

Endothelin-1 (ET-1) has been suggested to have a potential function as an inflammatory mediator. The study reported here assessed the putative inflammatory/nociceptive actions of the ET isopeptides using endothelin-B (ET(B))-receptor knockout (KO) mice and ET(A)- (SB 234551) and ET(B)- (A192621) selective antagonists. Phenylbenzoquinone (PBQ)-induced algesia was evident in the wild-type (WT) ET(B) (+/+) mice, attenuated by 80% in the heterozygous ET(B) (+/-) mice, and absent in the ET(B) (-/-) homozygotes. This was reproduced pharmacologically in WT ET(B) (+/+) mice where the algesic effect of PBQ was inhibited 74% by A192621, but unaffected by SB 234551 (both at 25 mg/kg p.o.). Similar observations were made in a model of cutaneous inflammation: ET(B) (+/+) mice had a marked inflammatory response to topical arachidonic acid, ET(B) (+/-) and ET(B) (-/-) mice had significantly reduced edema responses (37% and 65% inhibition). Neutrophil infiltration was reduced in the ET(B) (+/-) and ET(B) (-/-) mice (51% and 65% reduction, respectively). Topical administration of A192621 (500 microg/ear) inhibited arachidonic acid-induced swelling (39%) in WT ET(B) (+/+) mice. Collectively, these results support a role for the ET(B)-receptor in the mediation of inflammatory pain and cutaneous inflammatory responses. As such, the development of ET(B)-receptor-selective antagonists may be of therapeutic utility in the treatment of inflammatory disorders.

Endothelin B receptor modulates inflammatory pain and cutaneous inflammation.

The role of endothelin B (ET(B)) receptors in inflammation and nociception was examined using ET(B) receptor knockout mice. Genotyping studies were used with tissues from ET(B)((+/+)), ET(B)((+/-)), and ET(B)((-/-)) mice to confirm the loss of ET(B) receptors. Algesia induced by phenylbenzoquinone was evident in the (+/+) mice, reduced by approximately 80% in the (+/-) mice, and absent in the (-/-) mice. Phenylbenzoquinone-induced algesia in (+/+) mice was inhibited 74% by the ET(B) receptor-selective antagonist A192621 (25 mg/kg p.o.), but unaffected by the ET(A) receptor-selective antagonist SB 234551 (25 mg/kg p.o.). Noninflammatory pain, induced by hotplate, was equivalent between (+/+) and (-/-) mice. The cutaneous inflammatory response to topical arachidonic acid (AA) also was evaluated. Whereas (+/+) mice had a marked inflammatory response to AA, the (+/-), and (-/-) mice had significantly reduced fluid phase responses (37 and 65% inhibition, respectively). Neutrophil infiltration also was reduced in the (+/-) and (-/-) mice (51 and 65% reduction, respectively). Topical administration of A192621 (500 microg/ear) in (+/+) mice inhibited AA-induced swelling (39%), whereas SB 234551 (500 microg/ear) was without effect. Collectively, these results implicate the ET(B) receptor in mediation of inflammatory pain and cutaneous inflammatory responses in mice.

Hazardous waste. A North Carolina dilemma.

North Carolina, along with the rest of the nation, faces a number of dilemmas regarding management of hazardous waste: 1. North Carolina businesses and industries generate a lot of hazardous waste, but the state lacks the capacity to manage it. For many, it has been acceptable to ship the waste to other states for treatment, storage, and disposal. Some of the receiving states have indicated that they are no longer willing to serve as the "dumping ground" for North Carolina. 2. North Carolina, along with the EPA, has identified a number of hazardous waste sites now listed on the NPL. However, the state was excluded from its regional agreement with Alabama, South Carolina, Kentucky, and Tennessee in January 1991, meaning that Superfund monies may be withdrawn and that cleanup won't be completed at these sites. 3. Every year the country produces at least 260 million tons of hazardous waste--more than one ton for every man, woman, and child. Those opposed to constructing hazardous waste treatment facilities charge that businesses and industries should reduce their hazardous waste to zero or near zero, and they charge that the state is not doing enough to encourage waste reduction. North Carolina's hazardous waste regulations already require programs to minimize the amounts of waste generated by industries, but for most industrial processes, it is impossible to reduce the generation of waste to zero. However, industries must continue to reduce their waste through source reduction and recycling. Hazardous waste and toxic materials do pose a risk to human health and the environment unless properly managed.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of a worldwide spontaneous reporting system with cimetidine.

Adverse reactions to cimetidine have been identified through the manufacturer's Worldwide Spontaneous Reporting System. Reactions not observed during clinical trials-mental confusion, interstitial nephritis, and potentiation of oral anticoagulants-were identified and added to the prescribing information for cimetidine while further studies were undertaken. The monitoring of the drug's adverse reaction profile is ongoing so that new types of reactions can be identified.