Effects of d-amphetamine, pentobarbital, chlorpromazine and promazine on electric shock postponement responding by the pigeon

The effects of d-amphetamine, pentobarbital, chlorpromazine and promazine on responding under schedules of electric shock postponement were studied in pigeons. Responding was maintained by three different response-shock intervals (10, 20 and 60 seconds). Low doses (0.3-3 mg/kg) of d-amphetamine increased response rates without decreasing shock rates under all three response-shock intervals. The highest dose (10 mg/kg) of d-amphetamine increased the shock rates under all response-shock intervals and decreased the high response rate under the 10-second response-shock interval but did not decrease the lower rates of responding under the 20- and 60-second response-shock intervals. Pentobarbital decreased the high rate of responding maintained under the 10-second response-shock interval at lower dose (10 mg/kg) than the lower rates of under the 20- and 60-second response-shock intervals. The high dose (17.5 mg/kg) of pentobarbital decreased responding and the low doses (1-3 mg/kg) had no effect under all three response-shock intervals. Chlorpromazine (3-100 mg/kg) did not affect the average rate of responding under all response-shock intervals and only slightly increased shock rates under the 20- and 60-second response-shock intervals. Promazine (3-30 mg/kg) increased the rates of responding and decreased shock rates under all three response-shock intervals. Analysis of the temporal patterns of responding within the response-shock interval showed that d-amphetamine tended to induce the animals to respond earlier than they normally would in the response-shock interval while otherwise maintaining the temporal pattern of responding, pentobarbital decreased the probability of responses late in the response-shock interval, and chlorpromazine and promazine increased the probability of responses in the middle of the response-shock interval, producing a lessening of the temporal patterning of responding within the response-shock interval.     

(3SR,4aRS,6SR,8aRS)-6-(1H-tetrazol-5-yl)decahydroisoquinoline-3-carboxylic acid, a novel, competitive, systemically active NMDA and AMPA receptor antagonist

We report the synthesis and characterization of 6 (LY246492), which is a competitive N-methyl-D-aspartate (NMDA) and 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propanoic acid (AMPA) receptor antagonist. Tetrazole-substituted amino acid 6 was prepared in four steps from the recently described aldehyde 7. The optical isomers (-)-6 and (+)-6 were obtained from the same sequence of reactions using the corresponding isomers of 7. The compound displaces both NMDA and AMPA receptor binding and antagonizes depolarizations in cortical slices evoked by both NMDA and AMPA. In mice and pigeons, the compound showed antagonism of responses mediated through NMDA and AMPA receptors. Using the resolved optical isomers of 6, both NMDA and AMPA antagonist activities were found to reside in a single isomer, (-)-6.     

Synthesis and characterization of sol-gel silica films doped with size-selected gold nanoparticles

Homogeneous nanocomposite silica films uniformly doped with size-selected gold nanoparticles (AuNPs) have been prepared by a combined use of colloidal chemistry and the sol-gel process. For this purpose, stable thiol-functionalized AuNPs (DDT-AuNPs) were first synthesized by a two-phase aqueous/organic system and, subsequently, dispersed in an acid-catalysed sol-gel silica solution. The microstructural morphology of the samples was investigated by x-ray diffraction and field emission scanning electron microscopy. X-ray photoelectron spectroscopy (XPS) and UV-vis optical spectrophotometry were instead employed to investigate the elemental chemical behaviour and the evolution of the surface plasmon resonance (SPR) band of the AuNPs from their synthesis up to the formation of the Au-doped silica films. The results show that the size, shape and crystalline domains of the AuNPs remain unchanged during the entire preparation process, indicating that their aggregation or decomposition was prevented. XPS results show that the DDT-AuNPs lose the capping shells and oxidize themselves when dispersed in acid-catalysed sol-gel solutions, and that bare AuNPs are embedded in the SiO(2) films. A large broadening of the SPR band, observed for systems with DDT-AuNPs, suggests the presence of interface effects which cause a surface electron density lowering. Thiol chain detachment from the AuNPs determines an increase of the SPR peak intensity while the oxidation of the Au surfaces causes a red shift of its position. The latter is no longer observed in doped films, suggesting that no interfacial effects between bare AuNPs and the host medium are present.     

A polynomial-time maximum common subgraph algorithm for outerplanar graphs and its application to chemoinformatics

Metrics for structured data have received an increasing interest in the machine learning community. Graphs provide a natural representation for structured data, but a lot of operations on graphs are computationally intractable. In this article, we present a polynomial-time algorithm that computes a maximum common subgraph of two outerplanar graphs. The algorithm makes use of the block-and-bridge preserving subgraph isomorphism, which has significant efficiency benefits and is also motivated from a chemical perspective. We focus on the application of learning structure-activity relationships, where the task is to predict the chemical activity of molecules. We show how the algorithm can be used to construct a metric for structured data and we evaluate this metric and more generally also the block-and-bridge preserving matching operator on 60 molecular datasets, obtaining state-of-the-art results in terms of predictive performance and efficiency.     

A novel laminar-flow-based bioaerosol test system to determine biological sampling efficiencies of bioaerosol samplers

In this work, we describe a novel type of bioaerosol test system based on a laminar airflow chamber that provides a homogenous aerosol of microbial cells with known concentrations and defined culturability to bioaerosol samplers positioned in the chamber. In the system, three control and monitoring points (CMPs) are implemented in which the number and culturability of microbes can be determined by combining optical particle counting with microscopic and culture-based microbiological analyses. This lineup is designed to quantify the biological sampling efficiency (BSE) of a bioaerosol sampling device. Seven bioaerosol samplers were tested with four fungal and one bacterial species and their BSEs have been determined under optimized standard operating conditions. After executing tests with the appropriate statistical power, this new laminar-flow platform demonstrated the sensitivity necessary to determine significant differences in the recovery efficiency of viable fungal spores and bacterial cells in modern samplers. Under these test conditions, the samplers showed considerable differences in BSEs for the individual fungal and bacterial species. Our data demonstrate that a large number of experimental repetitions and measurements under tightly controlled and monitored conditions are necessary to quantify the BSE of a given sampler and to compare them to each other. Employing this system improves biological evaluation of samplers because natural environments are not suitable for this task due to their high variabilities in homogeneity and distribution of cells as well as fluctuations in culturability ratios.

© 2019 American Association for Aerosol Research