No description available.

Call number: LD2668 .T4 1951 P3 / Master of Science

No description available.

Call number: LD2668 .T4 1957 O95 / Master of Science

Reported here is an investigation to determine if azinphos-methyl (AZM), an organophosphate insecticide, adducts to hemoglobin, and if so, whether the hemoglobin adduct could be used as a quantitative marker of occupational AZM exposure. We hypothesized that AZM, or a metabolite of AZM, binds to hemoglobin in erythrocytes forming an adducted protein. We administered radiolabled AZM to rats and found a stable, dose-dependent association of radioactivity with hemoglobin. The decline in hemoglobin-associated radioactivity followed the expected kinetics of erythrocyte turnover in rats. We examined hemoglobin isolated from these rats by high-pressure liquid chromatography, liquid scintillation counting, and electrospray ionization mass spectrometry. These analyses provided evidence of AZM or an AZM metabolite binding to one of the beta proteins of hemoglobin. In vitro incubation of AZM with hemoglobin in a liver microsome system indicated an AZM adduct to heme. Further research is necessary to fully characterize the adduct and determine whether this biomarker will be useful for monitoring human exposure to AZM. / Graduation date: 2000

Call number: LD2668 .T4 1965 A51 / Master of Science

D.Sc. / Please refer to full text to view abstract

Call number: LD2668 .T4 1985 C52 / Master of Science

No description available.

Effects of developmental exposure to chlorpyrifos (CPS) or methyl parathion (MPS) on visuospatial, adaptive fear response, and passive avoidance memory and the signaling mechanisms responsible for these neurocognitive changes were investigated. Using an incremental low dose regimen, rat pups were orally gavaged daily with either corn oil (vehicle), CPS, or MPS from postnatal day 1 (PND1) -PND21. Cholinesterase activity was significantly inhibited with the highest dosages of CPS and MPS for up to 19 days after the last dosages. OP exposure impaired working and reference memory in males whereas in the females, enhancement occurred following CPS exposure. In addition, the adaptive fear response and passive avoidance retention memory was impaired in males whereas differential changes occurred in females. Accordingly, the behavioral deficits observed in males were persistent whereas the enhancement in females was transient. Males were more sensitive to OPs than females in that the medium and high dosages of CPS and MPS produced greater effects in females whereas all dosages of both compounds produced effects in males. Training in the radial arm maze significantly increased protein kinase C gamma (PKC ) expression and activity in the hippocampal membrane fraction of control rats whereas exposure to OPs exhibited a significant decrease in PKC and PKC immunoreactivity in both untrained and trained rats. However, MPS exposed females exhibited a significant increase in PKC expression in the cytosolic fraction but this was not related to improved memory. Reduction of membrane PKC expression and activity and cytosolic PKC expression and activity seemed to be related to visuospatial learning and memory deficits in exposed males but not exposed females. Brain-derived neurotrophic factor (BDNF) gene expression in the hippocampus was significantly increased (60%) in trained control males as compared to untrained control males. In contrast, trained and untrained females exhibited similar levels of BDNF gene expression. However, exposure of both sexes to either CPS or MPS significantly reduced the expression of BDNF in trained rats. In summary, these data indicate that OP exposure induced gender-specific changes in working memory formation and altered PKC isozyme levels/activity and BDNF expression.