ABSTRACT
Enzymes that efficiently hydrolyze highly toxic organophosphorus nerve agents could potentially be used as medical countermeasures. As sufficiently active enzymes are currently unknown, we synthesized twelve fluorogenic analogues of organophosphorus nerve agents with the 3-chloro-7-oxy-4-methylcoumarin leaving group as probes for high-throughput enzyme screening. This set included analogues of the pesticides paraoxon, parathion, and dimefox, and the nerve agents DFP, tabun, sarin, cyclosarin, soman, VX, and Russian-VX. Data from inhibition of acetylcholinesterase, in vivo toxicity tests of a representative analogue (cyclosarin), and kinetic studies with phosphotriesterase (PTE) from Pseudomonas diminuta, and a mammalian serum paraoxonase (PON1), confirmed that the analogues mimic the parent nerve agents effectively. They are suitable tools for high-throughput screens for the directed evolution of efficient nerve agent organophosphatases.
Subject(s)
Acetylcholinesterase/drug effects , Chemical Warfare Agents/chemistry , Cholinesterase Inhibitors/chemistry , Fluorescent Dyes/chemistry , Organophosphorus Compounds/chemistry , Organothiophosphorus Compounds/toxicity , Phosphoric Triester Hydrolases/chemistry , Animals , Aryldialkylphosphatase/chemistry , Chemical Warfare Agents/toxicity , Cholinesterase Inhibitors/chemical synthesis , Cholinesterase Inhibitors/toxicity , Coumarins/chemistry , Drug Evaluation, Preclinical/methods , Guinea Pigs , Hydrolysis , Kinetics , Male , Molecular Structure , Organophosphorus Compounds/chemical synthesis , Organophosphorus Compounds/toxicity , Organothiophosphorus Compounds/chemistry , Pesticides/chemistry , Structure-Activity RelationshipABSTRACT
BACKGROUND: It has been suggested that infection with Toxoplasma gondii is associated with slow reaction and poor concentration, whilst infection with Coxiella burnetii may lead to persistent symptoms of fatigue. METHODS: 425 farmers completed the Revised Clinical Interview Schedule (CIS-R) by computer between March and July 1999 to assess psychiatric morbidity. Samples of venous blood had been previously collected and seroprevalence of T. gondii and C. burnetii was assessed. RESULTS: 45% of the cohort were seropositive for T. gondii and 31% were positive for C. burnetii. Infection with either agent was not associated with symptoms reflecting clinically relevant levels of concentration difficulties, fatigue, depression, depressive ideas or overall psychiatric morbidity. CONCLUSIONS: We do not provide any evidence that infection with Toxoplasma gondii or Coxiella burnetii is associated with neuropsychiatric morbidity, in particular with symptoms of poor concentration or fatigue. However, this is a relatively healthy cohort with few individuals reporting neuropsychiatric morbidity and therefore the statistical power to test the study hypotheses is limited.
