Publications by authors named "Amsterdam C"

Problem: A shortage of curriculum-aligned formative multiple-choice questions (FMCQs) remains despite their known learning benefits in preclinical medical education due to limitations on teaching faculty time and other reasons. In response, students often use extramural resources such as commercial or collaborative question banks; however, these options are often expensive and cannot be aligned with the content of each school's unique curriculum. In addition, students need feedback on their learning in a manner that parallels the format of summative assessments.

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Introduction: Irwin/FOB testing is routinely conducted to investigate the neurofunctional integrity of laboratory animals during preclinical development of new drugs, however, the study design frequently varies to meet specific needs. Representatives of several European-based pharmaceutical companies performed a "state-of-the-art" assessment of how they conduct their CNS safety evaluation using Irwin/FOB tests.

Methods: This assessment consisted of (1) a survey of current/historical practice, (2) an evaluation of historical studies with reference compounds (amphetamine, chlorpromazine) to determine intercompany reproducibility of results, and (3) an interlaboratory test using reference compounds (MK-801, chlorpromazine) to determine whether partially standardized conditions (animals, sex, doses, vehicles, administration route, observation time points, systemic exposure) might reduce variability of results.

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Introduction: Excitation of Acetylcholine-mediated (Ach) transmission (especially if irreversible) may pose life-threatening adverse events by increasing neuronal network activity. Unfortunately, adequate detection of this liability during early drug development is hampered, because published ex vivo electrophysiological models are very insensitive to this regard. For example, Eserine, which reversibly inhibits acetylcholinesterase (AchE) in the double digit nM range, affects electrically evoked potentials in hippocampal slices only at ≥10μM.

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Rationale: The recently approved antidepressant vilazodone, a serotonin (5-HT)1A receptor partial agonist/selective 5-HT reuptake inhibitor offers new possibilities to study the underlying mechanisms of depression pharmacotherapy and of 5-HT augmenting antidepressants.

Objective: The role of the 5-HT1A receptor with respect to the regulation of 5-HT output in the mechanism of action of vilazodone.

Method: We measured 5-HT levels in two subregions of the rat prefrontal cortex by microdialysis, and 5-hydroxytryptophan (5-HTP) accumulation and tissue 5-HT concentrations ex vivo.

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The human gene RSC1A1 codes for a 67-kDa protein named RS1 that mediates transcriptional and post-transcriptional regulation of Na(+)-D-glucose cotransporter SGLT1. The post-transcriptional regulation occurs at the trans-Golgi network (TGN). We identified two tripeptides in human RS1 (Gln-Cys-Pro (QCP) and Gln-Ser-Pro (QSP)) that induce posttranscriptional down-regulation of SGLT1 at the TGN leading to 40-50% reduction of SGLT1 in plasma membrane.

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The discovery of a novel class of highly potent and selective 5-HT2A antagonists is reported herein. Selectivity for the serotonin 5-HT2A receptor was optimized, decreasing the affinity of these antagonists toward the adrenergic alpha1 and dopaminergic D2 receptors, and especially to the 5-HT2C receptor. A series of corresponding 7-substituted indoles is described for the first time as serotonergic ligands.

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Neutral chlorothiophenecarboxamides bearing an amino acid and a substituted aniline were synthesized and investigated for their factor Xa inhibitory activity in vitro. From selected 2-methylphenyl morpholinones the solution properties were determined. The most soluble and active compounds were then investigated in different animal species to compare the pharmacokinetic parameters.

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Systematic structural modifications of indolealkylphenylpiperazines led to improved selectivity and affinity within this class of 5-HT(1A) receptor agonists. Introduction of electron-withdrawing groups in position 5 on the indole raises serotonin transporter affinity, and the cyano group proved to be the best substituent here. 5-Fluoro and 5-cyano substituted indoles show comparable results in in vitro and in vivo tests, and bioisosterism between these substituents was supported by calculation of the molecular electrostatic potentials and dipole moments.

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A series of new 1-[4-(indol-3-yl)butyl]-4-arylpiperazines was prepared to identify highly selective and potent 5-HT(1A) agonists as potential pharmacological tools in studies of mood disorders. The combination of structural elements (indole-alkyl-amine and aryl-piperazine) known to introduce 5-HT(1A) receptor affinity and the proper selection of substituents (R on the indole moiety and R' on the aryl moiety) led to compounds with high receptor specificity and affinity. In particular, the introduction of the methyl ether or the unsubstituted carboxamide as substituents in position 5 of the indole (R) guaranteed serotonergic 5-HT(1A) affinity compared to the unsubstituted analogue.

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The dual serotonin (5-HT) re-uptake inhibitor and 5-HT(1A) receptor agonist vilazodone was found to increase central serotonin levels in rat brain. In the course of structural modifications of vilazodone 3-[4-[4-(2-oxo-2H-1-benzopyran-6-yl)-1-piperazinyl]-butyl]-1H-indole-5-carbonitrile 8i and its fluorine analogue 6-[4-[4-(5-fluor-3-indolyl)-butyl]-1-piperazinyl]-2H-1-benzopyran-2-one have been identified. These unsubstituted chromenones are equally potent at the 5-HT(1A) receptor and 5-HT transporter.

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Sarizotan exhibited high affinities only to serotonin 5-HT1A receptors and dopamine DA D4>D3>D2 receptors with the profile of a 5-HT1A agonist and DA antagonist demonstrated by the inhibition of cAMP-stimulation and guinea pig ileum contraction, decreased accumulation of the 5-HT precursor 5-hydroxytryptophan and increased levels of 5-HT metabolites, increased accumulation of DA precursor dihydroxyphenylalanine (DOPA) and the reduced levels of DA metabolites in intact rats. However, sarizotan at higher doses decreased DA precursor accumulation in reserpinized rats and induced contralateral rotational behavior in unilaterally substantia nigra lesioned rats, indicating some intrinsic dopaminergic activity; at D2 receptors sarizotan may act as a partial agonist, depending on the dopaminergic impulse flow. Sarizotan represents a new approach for the treatment of extrapyramidal motor complications such as l-DOPA-induced dyskinesia in Parkinson's disease.

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The 5-HT2A receptor ligand 7-[4-[2-(4-fluoro-phenyl)-ethyl]-piperazine-1-carbonyl]-1H-indole-3-carbonitrile HCl (EMD 281014) selectively binds to human (h) and rat 5-HT2A receptors (IC50 values 0.35 and 1 nM, respectively; vs. 1334 nM for h5-HT2C) and inhibited 5-HT-stimulated [35S]guanosine 5'-O-3-thiotriphosphate (GTPgammaS)-accumulation in h5-HT2A transfected Chinese hamster ovary cells (IC50 9.

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As part of our research program toward new, potential antidepressants, a series of unsymmetrical ureas has been prepared and evaluated as 5-HT reuptake inhibitors with 5-HT(1B/1D) antagonistic activities. The design of these compounds was based on coupling of various indole derivatives, previously shown to inhibit 5-HT reuptake, to three different aniline moieties, which are part of known 5-HT(1B/1D) ligands. Binding experiments in rat frontal cortex using [(125)I]iodocyanopindolol, in calf striatum using [(3)H]5-HT, and in rat hippocampus using [(3)H]8-OH-DPAT as radioligands, respectively, revealed significantly higher affinity at the 5-HT(1B) receptor as compared to the affinities for the 5-HT(1A) and 5-HT(1D) receptors for a number of compounds, among them 4-(5-fluoro-1H-indol-3-yl)piperidine-1-carboxylic acid [4-methoxy-3-(4-methylpiperazin-1-yl)phenyl]amide (5), the corresponding 4-fluoro-1H-indol-3-yl analogue 21a, and the corresponding 6-fluoro-1H-indol-3-yl analogue 21b.

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A series of new analogues of N-[4-methoxy-3-(4-methylpiperazin-1-yl)phenyl] 2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)biphenyl-4-carboxamide (1; GR127935) as potent and selective 5-HT(1B/1D) antagonists were synthesized and evaluated pharmacologically. Their receptor binding profiles were comparable to that of 1. The 1,3,4-oxadiazole isomer 2 and the 4'-aminocarbonyl and 4'-amidinyl analogues (9 and 10) of 1 had higher affinities at the rat 5-HT(1B) receptor (IC(50) = 0.

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The hydroxyl radical is a very reactive oxygen species that damages biomolecules in the brain and in other tissues. The possible pharmacological intervention to prevent hydroxyl radical formation was studied in vivo using the microdialysis technique in brains of nonanesthetized rats. Hydroxyl radicals form stable adducts [mainly 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-DHBA)] via an aromatic hydroxylation reaction with salicylic acid.

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Fast, simple and accurate methods for the determination of SDZ ICM 567, the 7-methoxy derivative of tropisetron, in microdialysates have been developed. Sampling by microdialysis from freely moving rats in the portal and jugular vein offers a new technology for pharmacokinetic studies by direct and continuous measurement of unbound drug concentrations with time. SDZ ICM 567 can be identified in small sample volumes of dialysates on a microbore high-performance liquid chromatography column-switching system with ultraviolet detection.

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