Publications by authors named "Petko W"

A hallmark of the immunopathology associated with Alzheimer's disease (AD) is the presence of activated microglia surrounding senile plaque deposits of beta-amyloid (A beta) peptides. A beta peptides have been shown to be potent activators of microglia and macrophages, but little is known about endogenous factors that may modulate their responses to amyloid. We investigated whether the 'anti-inflammatory' cytokines IL-4, IL-10 and IL-13 could regulate A beta-induced production of the inflammatory cytokines IL-1 alpha, IL-1 beta, TNF-alpha, IL-6 and the chemokine MCP-1.

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We investigated a potential role for the soluble interleukin-6 receptor (sIL-6R) in modulating interleukin-6 (IL-6) function in the central nervous system by assessing IL-6 and sIL-6R effects on beta-amyloid precursor protein (beta-APP) transcription and expression in cells of human neuronal origin. Cells transfected with a luciferase reporter plasmid containing a 3.8 kb DNA fragment of the beta-APP promoter were shown to have inducible promoter activity when treated with phorbol ester or basic fibroblast growth factor, but not when treated with lipopolysaccharide or Il-6.

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Expression of the beta-amyloid precursor protein (beta-APP), a proteoglycan whose proteolytically derived fragments have been implicated in the neuropathology observed in Alzheimer's disease, is regulated by a variety of stimuli including cytokines, phorbol esters, and growth factors. In this study we report the effects of basic fibroblast growth factor (bFGF) and the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), on beta-APP expression and secretion in SKNMC human neuroblastoma cells. Treatment of the cells with bFGF for 24 h increased APP promoter activity 200%, cell-associated full-length protein 189%, and secreted amino-terminal fragments 192% compared to basal levels.

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1-[(3-Fluoro-4-pyridinyl)amino]-3-methyl-1(H)-indol-5-yl methyl carbamate (P10358) is a potent, reversible acetylcholinesterase inhibitor that produces central cholinergic stimulation after oral and parental administration in rats and mice. P10358 is a 2.5 times more potent acetylcholinesterase inhibitor than THA in vitro (IC50 = 0.

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Attenuating beta-amyloid precursor protein (beta-APP) gene expression may have relevance in diseases such as Alzheimer's disease, where beta-APP has been implicated in neuropathological processes. We report here on the transcriptional down-regulation of beta-APP by interferon-gamma (IFN-gamma) in SKNMC human neuroblastoma cells. Treatment of the cells with IFN-gamma resulted in a 85% dose-dependent inhibition of beta-APP promoter activity after 24 h of exposure, with no changes observed at 5 h.

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Examination of HP 184, [N-n-propyl)-N-(3-fluoro-4-pyridinyl) -1H-3-methylindodel-1-amine hydrochloride], in a variety of tests for serotonergic activity revealed some unique properties of this compound. We report here that 100 microM HP 184 enhanced spontaneous release of [3H]serotonin (5-HT) from rat hippocampal slices. This release was independent of the uptake carrier.

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Acetylcholinesterase (AChE) inhibitors from several chemical classes have been tested for the symptomatic treatment of Alzheimer's disease; however, the therapeutic success of these compounds has been limited. Recently, another AChE inhibitor, galanthamine hydrobromide (GAL), has shown increased clinical efficacy and safety. Using biochemical, behavioral and pharmacokinetic analyses, this report compares GAL with two of its analogs, 6-O-acetyl-6-O-demethylgalanthamine hydrochloride (P11012) and 6-O-demethyl-6-O[(adamantan-1-yl)-carbonyl]galanthamine hydrochloride (P11149), for their therapeutic potential.

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A novel series of substituted (pyrroloamino)pyridines was synthesized, and the compounds were evaluated for cholinomimetic-like properties in vitro (inhibition of [3H]quinuclidinyl benzilate binding) and in vivo (reversal of scopolamine-induced dementia) as potential agents for the treatment of Alzheimer's disease. Compounds displaying significant activity were more broadly evaluated, which revealed the presence of a desirable adrenergic component of activity. The synthesis and structure-activity relationships for this series is presented, along with the biological profiles of selected compounds.

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A series of novel N-(4-pyridinyl)-1H-indol-1-amines and other heteroaryl analogs was synthesized and evaluated in tests to determine potential utility for the treatment of Alzheimer's disease. From these compounds, N-propyl-N-(4-pyridinyl)-1H-indol-1-amine (besipirdine, 4c) was selected for clinical development based on in-depth biological evaluation. In addition to cholinomimetic properties based initially on in vitro inhibition of [3H]quinuclidinyl benzilate binding, in vivo reversal of scopolamine-induced behavioral deficits, and subsequently on other results, 4c also displayed enhancement of adrenergic mechanisms as evidenced in vitro by inhibition of [3H] clonidine binding and synaptosomal biogenic amine uptake, and in vivo by reversal of tetrabenazine-induced ptosis.

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Previous studies have shown that, at concentrations of 1 microM and 10 microM, HP 749 increased electrically-stimulated release of [3H]norepinephrine (NE) from rat cortical slices. These effects were Ca(2+)-dependent, indicating an effect on release from vesicular stores. At 100 microM, HP 749 had two effects.

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4-Amino-3-pyridyl carbamates (2a-c) were synthesized as potential acetylcholinesterase inhibitors and acetylcholine releasers on the basis of the reported activity of the analogous N-(4-amino-3-pyridyl)-N',N'-dimethylurea (1). Although 4-amino-3-pyridyl N,N-dimethylcarbamate (2b) showed good cholinesterase inhibition [concentration that elicited a 50% reduction in the maximal enzyme response (IC50) was 13.4 microM], it had no effect on the stimulated release of [3H]acetylcholine from rat striatal slices.

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A series of 3-substituted-6-fluoro-1,2-benzisoxazoles (II) was synthesized and evaluated for potential antipsychotic activity. Many of the compounds displayed potent antipsychotic-like activity in the apomorphine induced climbing in mice (CMA) or spiroperidol binding assays, and compound 42 (HRP 392, 1-[3-(6-fluoro-1,2-benzisoxazol-3-yl)propyl]-4-(2-methoxyphenyl) piperazine) was selected for more detailed antipsychotic evaluation in a battery of preclinical assays. The results of these studies suggests that 42 is a potential antipsychotic drug with less propensity for EPS than some standard neuroleptics in monkeys.

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