Carbamate protection of AChE against inhibition by agricultural chemicals.

The carbamate pyridostigmine bromide has been used as a pretreatment to protect individuals from the nerve agent soman. Previous research showed that pyridostigmine significantly protected human muscle acetylcholinesterase in vitro from soman and bovine red blood cell acetylcholinesterase from some organophosphorous pesticides. Research presented here demonstrates that pretreatment with other carbamates also protects acetylcholinesterase from inhibition by the pesticides chlorpyrifos-oxon and diazinon-oxon, but not from malaoxon.

Chronic hydrocarbon exposure of harlequin ducks in areas affected by the Selendang Ayu oil spill at Unalaska Island, Alaska.

We evaluated chronic exposure of harlequin ducks (Histrionicus histrionicus) to hydrocarbons associated with the 2004 M/V Selendang Ayu oil spill at Unalaska Island, Alaska. We measured levels of hepatic 7-ethoxyresorufin-O-deethylase activity (EROD) in liver biopsy samples as an indicator of hydrocarbon exposure in three oiled bays and one reference bay in 2005, 2006, and 2008. Median EROD activity in ducks from oiled bays was significantly higher than in the reference bay in seven of nine pairwise comparisons.

Pyridostigmine bromide protection against acetylcholinesterase inhibition by pesticides.

Pyridostigmine bromide (PB) has been used to protect soldiers from the toxic effects of soman, a chemical warfare agent. Recent research shows that pyridostigmine bromide protects a significant percentage of acetylcholinesterase in isolated human intercostal muscle. Findings presented here indicate that red blood cell acetylcholinesterase is similarly protected by pyridostigmine bromide from the action of diisopropyl fluorophosphate and several organophosphate pesticides including chlorpyrifos-oxon, diazinon-oxon, and paraoxon, but not malaoxon, using the bovine red blood cell as a subject.

Protection of human muscle acetylcholinesterase from soman by pyridostigmine bromide.

Introduction: Pretreatment with pyridostigmine bromide (PB) of human intercostal muscle fibers exposed to the irreversible acetylcholinesterase (AChE) inhibitor soman was investigated.

Methods: Muscles were pretreated with 3 × 10(-6) M PB or saline for 20 minutes, then exposed to 10(-7) M soman for 10 minutes.

Results: AChE of muscles treated with soman alone was inhibited >95%.

Cytochrome P4501A biomarker indication of the timeline of chronic exposure of Barrow's goldeneyes to residual Exxon Valdez oil.

We examined hepatic EROD activity, as an indicator of CYP1A induction, in Barrow's goldeneyes captured in areas oiled during the 1989 Exxon Valdez spill and those from nearby unoiled areas. We found that average EROD activity differed between areas during 2005, although the magnitude of the difference was reduced relative to a previous study from 1996/1997, and we found that areas did not differ by 2009. Similarly, we found that the proportion of individuals captured from oiled areas with elevated EROD activity (≥ 2 times unoiled average) declined from 41% in winter 1996/1997 to 10% in 2005 and 15% in 2009.

Selenium accumulation in coturnix quail fed seleno-L-methionine.

The accumulation of selenium in Coturnix quail, a sensitive species to selenium toxicity, was studied. Quail were fed diets containing 0.7 µg/g (control), 12 µg/g (low-Se), and 22 µg/g (high-Se) as seleno-L-methionine for four weeks.

Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill.

Hydrocarbon-inducible cytochrome P4501A (CYP1A) expression was measured, as ethoxyresorufin-O-deethylase (EROD) activity, in livers of wintering harlequin ducks (Histrionicus histrionicus) captured in areas of Prince William Sound, Alaska, USA, oiled by the 1989 Exxon Valdez spill and in birds from nearby unoiled areas, during 2005 to 2009 (up to 20 years following the spill). The present work repeated studies conducted in 1998 that demonstrated that in harlequin ducks using areas that received Exxon Valdez oil, EROD activity was elevated nearly a decade after the spill. The present findings strongly supported the conclusion that average levels of hepatic EROD activity were higher in ducks from oiled areas than those from unoiled areas during 2005 to 2009.

Normal range of human red blood cell acetylcholinesterase activity.

The normal range of human erythrocyte acetylcholinesterase (RBC-AChE) activity is important when monitoring exposure to pesticides and chemical warfare agents. A modification of Michel's method measured RBC-AChE activities from 991 individuals (818 males and 173 females) presumably unexposed to nerve agents. Median age was 42 (range, 18-76) years.

Blood cholinesterases from Washington State orchard workers.

Court-ordered monitoring of blood cholinesterases (ChEs) from orchard workers in Washington State is underway. In 2008, the mean red blood cell acetylcholinesterase (AChE, EC 3.1.

Polycyclic aromatic hydrocarbon exposure in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) in the eastern Aleutian Islands, Alaska, USA.

Seaducks may be affected by harmful levels of polycyclic aromatic hydrocarbons (PAHs) at seaports near the Arctic. As an indicator of exposure to PAHs, we measured hepatic enzyme 7-ethoxyresorufin-O-deethylase activity (EROD) to determine cytochrome P4501A induction in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) from Unalaska, Popof, and Unga Islands (AK, USA) in 2002 and 2003. We measured PAHs and organic contaminants in seaduck prey samples and polychlorinated biphenyl congeners in seaduck blood plasma to determine any relationship to EROD.

Determination of cholinesterase in blood and tissue.

The widespread use of organophosphate and organocarbamate pesticides and the dangers of related chemical warfare agents dramatize the importance of rapid, accurate, and sensitive assays for blood and tissue cholinesterases (ChEs), important targets for neurotoxic chemicals. Two ChE enzymes used as biomarkers of exposure are the specific acetylcholinesterases (AChE, EC 3.1.

Monitoring cholinesterases to detect pesticide exposure.

Progress toward a standard blood cholinesterase assay to assess pesticide exposures in the agricultural workplace and to identify possible victims of chemical warfare agents is discussed. Examples given are drawn from collaborations with clinical laboratories in California and the Department of Defense Cholinesterase Reference Laboratory (CRL).

Cholinesterases in aquatic biomonitoring: assay optimization and species-specific characterization for a California native fish.

Cholinesterase (ChE) enzyme activity measurements are widely applied in aquatic organisms for water quality monitoring, especially for pesticide contamination in agricultural watersheds. These biomarkers are amenable to measurement in a variety of species, and are therefore useful for examining effects in model organisms relevant to the ecosystem of interest. However, extensive variation in ChE biochemistry exists among tissues and species.

Influence of water temperature on acetylcholinesterase activity in the Pacific tree frog (Hyla regilla).

This investigation evaluated whether acetylcholinesterase (AChE) in Pacific tree frogs (Hyla regilla) from different geographical locations was influenced by different temperatures during early aquatic life stages, independent of pesticide exposure. Tadpoles were collected from both a California coastal pond and a Sierra Nevada mountain range pond, USA. Groups of frogs from each location were raised in temperatures representative of either the Sierra Nevada (8 degrees C) or the coastal (19 degrees C) location.

Toxicity of storm-water runoff after dormant spray application in a french prune orchard, Glenn County, California, USA: temporal patterns and the effect of ground covers.

Organophosphorous (OP) insecticides, especially diazinon, have been detected routinely in surface waters of the Sacramento and San Joaquin River watersheds, coincident with rainfall events following their application to dormant orchards during the winter months. Preventive best management practices (BMP) aim at reducing off-site movement of pesticides into surface waters. Two proposed BMPs are: The use of more hydrophobic pyrethroid insecticides believed to adsorb strongly to organic matter and soil and the use of various types of ground cover vegetation to increase the soil's capacity for water infiltration.

Meeting requirements of the California cholinesterase monitoring program.

California (CA) has a long-standing formal blood cholinesterase (ChE) monitoring program for mixers, loaders, and applicators of pesticides. When the authors found commercial clinical kits were not optimal for assaying blood ChEs, CA regulations were revised to specify use of the Ellman ChE assay or to demonstrate a conversion factor with a correlation (r(2)) of 0.9 or better.

Molecular and cellular biomarker responses to pesticide exposure in juvenile chinook salmon (Oncorhynchus tshawytscha).

We determined the effects of two pesticides, chlorpyrifos and esfenvalerate in juvenile Chinook salmon. Four to five month old salmon were exposed to a range of pesticide concentrations, and tissue samples of surviving fish were analyzed for stress protein expression, cytokine transcription, and acetylcholinesterase (AChE) activity. At the highest concentrations, both pesticides led to complete mortality, whereas medium and low concentrations resulted in high survival rates.

Standardization of clinical cholinesterase measurements.

Previous studies showed that commonly used kits for measuring cholinesterases were not optimal for determining acetylcholinesterase (AChE) activity. Clinical use of different kits and methodologies resulted in AChE levels being reported in different units and activities that were not reproducible among laboratories. Findings such as these led to a revision in California regulations (covering AChE measurements for pesticide worker safety) calling for clinical laboratories to standardize their findings.

Cholinesterase measurements with an automated kit.

Background: The Test-mate kit determines acetylcholinesterase (AChE, EC 3.1.1.

Actions of pyridostigmine and organophosphate agents on chick cells, mice, and chickens.

Gulf War veterans were given pyridostigmine bromide (PB) tablets to enhance the therapeutic effect of antidotes to nerve agents in the event of exposure. The goal of this research is to examine whether combined exposure to PB and sarin (agent GB) is more neurotoxic to sensitive surrogate animals, mice and chickens, than if given separately. Scoping trials were performed to establish appropriate dose-response ranges for sarin and control chemicals.