Cholinesterase inhibitors and stress: effects on brain muscarinic receptor density in mice.

Exposure to the reversible cholinesterase inhibitor, pyridostigmine bromide (PB), in conjunction with stress, has been suggested as a possible cause of Gulf War Syndrome. This work explores the hypothesis that PB exposure coupled with stress will alter cholinergic receptor density based on the rationale that prolonged exposure to PB and stress will lead to increased stimulation of cholinergic receptors due to the reduced capacity to degrade acetylcholine, leading to changes in receptor levels. Male C57Bl6 mice were exposed to PB (3 or 10 mg/kg/day) or physostigmine (2.

Antibiotic resistance of gram-negative bacteria in rivers, United States.

Bacteria with intrinsic resistance to antibiotics are found in nature. Such organisms may acquire additional resistance genes from bacteria introduced into soil or water, and the resident bacteria may be the reservoir or source of widespread resistant organisms found in many environments. We isolated antibiotic-resistant bacteria in freshwater samples from 16 U.