Life Sciences Commons^™

Evidence That Nicotine Can Acutely Desensitize Central Nicotinic Cholinergic Receptors In Vivo, John Randolph James

Theses and Dissertations

Current concepts concerning nicotine's central nervous system (CNS) mechanism(s) of action suggest that this drug is producing its effects via an interaction at nicotiniccholinergic receptors (nAChRs) which open a membrane cation channel. Following initial opening of the channel, nicotine appears to induce a rapid desensitization of the nAChRs, closing the channel and resulting in a cessation of nicotine's effects. Research presented here will provide evidence of this secondary desensitization process in vivo by demonstrating nicotine's ability to induce acute tolerance in the discriminative stimulus (DS) paradigm. The ability of nicotine to elicit DS control of behavior was significantly reduced via …

Stem Cell Factor In Mast Cell And Schwann Cell Proliferation And Hyperplasia, John Joseph Ryan

Theses and Dissertations

Stem cell factor (SCF) is a recently characterized hematopoietic growth factor capable of stimulating the proliferation and differentiation of many hematopoietic cells, including the mast cell. We have cloned the gene encoding SCF from a cDNA library prepared from NIH 3T3 fibroblasts, and have characterized the ability of recombinant SCF to induce the development of mast cell-committed progenitors (MCCP), found in the mesenteric lymph nodes of mice infected with Nippostrongylus brasiliensis (Nb-MLN), but not naive mice. We have also examined Schwann cells, mast cells, and reproductive tissues for their ability to produce SCF.

We have found that recombinant …

Pharmacological Manipulation Of Protein Kinase C Modulates The Growth And Lineage Commitment Of Enriched Human Myeloid Progenitor Cells Induced By Hematopoietic Growth Factors, Fei Li

Theses and Dissertations

The activity of protein kinase C (PK-C) has been implicated in regulating the growth and differentiation of both normal and neoplastic hematopoietic cells. We have examined the effects of the PK-C activators, phorbol 12,13- dibutyrate, mezerein, and bryostatin 1, on the proliferation and lineage commitment of enriched CD34+ human myeloid progenitor cells stimulated by lL-3, GM-CSF, stem cell factor and the lL-3/GM-CSF hybrid cytokine plXY321. Coadministration of these PK-C activators with plateau concentrations of rlL-3 or rGM-CSF induced 100-150% increase in the number of day 14 CFU-GM.with a selective stimulation on neutrophil and macrophage lineages while inhibiting eosinophilic growth. plXY321 …