Foundations of chemical microscopy. 1. Solid-state characterization of 5-nitrobarbituric acid (dilituric acid) and its complexes with group IA and group IIA cations.

5-Nitrobarbituric acid (dilituric acid) has been used as a chemical microscopic reagent for the qualitative identification of alkali metal (Group IA) and alkaline earth (Group IIA) cations. This methodology was based on the characterization of observed crystal morphologies, since a unique crystal habit could be associated with each adduct product. To understand the scientific foundations which permitted chemical microscopy to function as a useful analytical technique, the products formed between dilituric acid and the Group IA and IIA cations were characterized using polarizing optical microscopy, powder X-ray diffraction, thermal analysis and solid-state nuclear magnetic resonance.

A comparison of the CPAP performance characteristics of the Puritan-Bennett 7200a and a prototype continuous pressure-regulating ventilator.

Background: A prototype demand-flow medical ventilator for intensive care unit (ICU) applications has been developed with the ability to maintain continuous pressure regulation of proximal airway pressure during both inspiratory and expiratory respiratory phases. The performance of this system was investigated in laboratory tests of continuous positive airway pressure (CPAP) mode, a ventilatory mode in which airway pressure regulation is strongly challenged.

Materials & Methods: Comparative tests of the pressure-regulating ventilator (PRV) prototype and a Puritan-Bennett 7200a (PB7200a) ventilator were made in three performance categories: pressure-volume product error, peak pressure error during inspiration, and peak pressure error during expiration.

Substituent effects on the excited-state properties of platinummeso-tetraphenylporphyrins.

A study has been undertaken to examine the effect of peripheral substitution on the photophysics of platinum tetraarylporphyrins. The aim of the study was to provide better dyes for oxygen sensing. Substitution of electron rich aryl groups results in red shifts for both the absorption and emission spectra.

Synthesis and in vitro evaluation of [Leu13]porcine motilin fragments.

Several peptide fragments representing N-terminal, C-terminal, and internal sequences of [Leu13]porcine motilin ([Leu13]pMOT) were synthesized using Fmoc solid phase methodology. Peptides were assayed for motilin receptor binding activity in a rabbit antrum smooth muscle preparation and for stimulation of contractile activity in segments of rabbit duodenum. In vitro activity was directly correlated with motilin receptor binding affinity for all [Leu13]pMOT fragments examined.

Molecular modeling of 5-HT3 receptor ligands.

Ligands of various chemical classes (e.g., indoles, indazoles, benzamides, carbazoles, and quinolines) have demonstrated high affinity for the 5-HT3 receptor in radiolabeled ligand-binding studies, and have shown 5-HT3 receptor antagonistic activity in functional assays which utilize the excitatory effects of 5-HT on enteric neurons and autonomic afferents.

Capillary zone electrophoresis studies of motilin peptides. Effects of charge, hydrophobicity, secondary structure and length.

Motilin is a gut hormone, which is involved in gastrointestinal motility. Capillary electrophoresis studies were made on 24 peptides that are N-terminal, C-terminal or internal fragments of motilin. The isoelectric point, total charge and hydrophobicity were calculated for all of the peptides.

Chiral high-performance liquid chromatography of aromatic cyclic dipeptides using cyclodextrin stationary phases.

A series of enantiomers of cyclic and linear dipeptides containing aromatic amino acids was prepared and chromatographed on beta- and gamma-cyclodextrin (CD) columns. The retention times, separation factor alpha and resolution values were calculated. The relevance of the distance of the chiral center from the phenyl ring for chiral resolution was studied.

4-Phenyl- and 4-heteroaryl-4-anilidopiperidines. A novel class of analgesic and anesthetic agents.

The incorporation of the 4-phenylpiperidine pharmacophore found in morphine into 4-anilidopiperidines related to fentanyl (1) led to a novel class of potent opioid analgesic and anesthetic agents with a favorable pharmacological profile. The synthesis, analgesic activity, and anesthetic properties of a series of 4-phenyl-4-anilidopiperidines (13-29) are discussed. Isosteric replacement of the phenyl by various heteroaryl substituents extended the series to include 4-heteroaryl-4-anilidopiperidines (30-53).