No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

A physiologic model for phencyclidine disposition in the rat was established. This model was able to accurately predict phencyclidine disposition in most rat tissues. Physiologic models are based on actual physiologic, anatomic, and biochemical considerations. As a result, these models can be used to predict drug disposition under conditions of altered physiology or anatomy. This aspect of physiologic modeling was tested in the present study by examining the ability of the model to predict phencyclidine plasma disposition in dog and man. The model developed in this study was able to accurately predict phencyclidine disposition in these species. A primary goal of this project was to evaluate the effects of the administration of an anti-phencyclidine monoclonal antibody on phencyclidine disposition and toxicity in the rat. The monoclonal antibody was produced in murine ascites fluid. The antibody was purified using a recirculating isoelectric focusing apparatus. This method provided a rapid technique which can be used to purify monoclonal antibody from large quantities of ascites fluid, yielding reasonably good antibody recovery and very high purity. Characterization of the antibody showed only moderate affinity and high cross reactivity. Administration of the monoclonal antibody did not significantly alter either phencyclidine disposition or toxicity. While qualitative differences in recovery from phencyclidine-induced toxicity occurred in rats receiving the anti-phencyclidine antibody, these differences failed to be statistically different from control rats. These results may be explained by the poor qualities (moderate affinity, high cross-reactivity) of the monoclonal antibody.

Tissue sequestration and biliary elimination are two of the important mechanisms by which mammalian body defends against heavy metal insults. In rats or rabbits that had received Pb, Cd, Hg, As and ²¹⁰Po, these metal ions were sequestered in the choroid plexus at concentrations of Pb, Cd, Hg, As and Po that were 57, 33, 12, 13 and 5 times higher, respectively, than those found in the brain cortex. In addition, the concentrations of these heavy metal ions were many fold greater in the choroid plexus than in the CSF or blood. The accumulation of Pb in the choroid plexus was dose-dependent and time-related. When the choroid plexus was incubated, in vitro, with ouabain, the latter significantly inhibited the uptake of Cd from the CSF side of the choroid plexus. Cystine concentration was four times greater in the choroid plexus than in brain cortex. Results suggest that the choroid plexus sequesters toxic metal and metalloid ions. It appears to do this in order to protect the CSF and brain from toxic heavy metals in the blood. The effect of N-(2,3-dimercaptopropyl) phthalamidic acid (DMPA), meso-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto-1-propane sulfonic acid (DMPS) on biliary excretion of Cd was studied in rat chronic intoxication mode. DMPA (0.10 mmol/kg, iv), when given to rats three days after exposure to Cd, elicited within 30 min a 20-fold increase in biliary Cd excretion. GSH in rat bile was also increased three fold as compared to control. Neither DMSA nor DMPS increased biliary Cd or GSH. Upon iv administration, DMPA, not DMSA, appeared in bile. An altered, presumably disulfide, form of DMPS was also found in bile. Incubation of DMPA or DMSA with Cd-saturated MT resulted in the removal of Cd from MT. DMPS, however, promoted the formation of MT polymers. DMPA protected biliary GSH from autoxidation. Gel filtration and autoradiographic study of rat bile samples showed that the radioactivity of Cd was correlated with both GSH and DMPA. The evidence supports the mechanism that the increase of biliary Cd by DMPA is the result of DMPA entering cells and removing Cd from MT. Protection of GSH autoxidation by DMPA may facilitate Cd elimination via the bile.

MCF7 cell cultures exposed to cyclosporine A (CsA) from 1-5 μM and from 0-48 hr have decreased viability and clonogenic ability. When these cells are examined by indirect immunofluorescence for cytoskeletal filaments, there is altered cell shape, but no alteration in microfilaments or microtubules. However, there is a collapse in cytokeratin intermediate filament arrays resulting in a peri-nuclear reorganization at 24-48 hr incubation (5 μM). When MCF7 cells are pre-treated in 5 μM CsA for 24 hr, and then placed in non-drug media for 12-24 hr, there is recovery of cytokeratin arrays and cell shape. Analysis of cytokeratin proteins by 2-D electrophoresis depict decreased phosphorylated proteins at 2-5 μM CsA (24 hr). CsA (1-5 μM CsA, 1-48 hr) inhibits phosphate content on cytokeratin protein to 35% levels on cytokeratin #8, and to 50% levels on cytokeratins #18, and #19. CsA decreases phosphate content on cytokeratin protein during incorporation, at steady state, and during turnover. Determinations of phosphate loss indicate that CsA increases turnover at greater levels than it inhibits incorporation, suggesting the activation of a phosphatase enzyme. CsA-induced decreased phosphorylation levels can be rescued by addition of 100 nM 12-o-tetradecanoylphorbol-13-acetate (TPA), but not upon addition of 50 μM forskolin. This indicates a CsA-sensitive protein kinase C site on cytokeratin protein. An in vitro urea assay was utilized to examine assembly and disassembly or cytokeratin protofilaments. CsA (5 μM, 48-72 hr) does not alter assembly of cytokeratin protofilaments from monomeric proteins. Analysis of disassembly of protofilaments into monomeric units resulted in CsA-induced (5 μM, 48-72 hr) inhibition of disassembly. Regulation of phosphorylation may therefore be important in the assembly and disassembly of cytokeratin filaments, and a resistance to disassembly may indicate a CsA interaction that is toxic to the cell.