Stereochemistry and molecular pharmacology of (S)-thio-ATPA, a new potent and selective GluR5 agonist.

(RS)-2-Amino-3-(5-tert-butyl-3-hydroxy-4-isothiazolyl)propionic acid (thio-ATPA), a 3-isothiazolol analogue of (RS)-2-amino-3-(5-tert-butyl-3-hydroxy-4-isoxazolyl)propionic acid (ATPA), has previously been shown to be a relatively weak AMPA receptor agonist at native (S)-glutamic acid ((S)-Glu) receptors (EC(50)=14 microM), comparable in potency with ATPA (EC(50)=34 microM). Recent findings, that (S)-ATPA is a potent (EC(50)=0.48 microM) and selective agonist at homomerically expressed ionotropic GluR5, prompted us to resolve thio-ATPA using chiral chromatography and pharmacologically characterize the two enantiomers at native as well as cloned ionotropic glutamate receptors.

Construction of a high affinity zinc binding site in the metabotropic glutamate receptor mGluR1: noncompetitive antagonism originating from the amino-terminal domain of a family C G-protein-coupled receptor.

The metabotropic glutamate receptors (mGluRs) belong to family C of the G-protein-coupled receptor (GPCR) superfamily. The receptors are characterized by having unusually long amino-terminal domains (ATDs), to which agonist binding has been shown to take place. Previously, we have constructed a molecular model of the ATD of mGluR1 based on a weak amino acid sequence similarity with a bacterial periplasmic binding protein.

Synthesis of 1-hydroxy-substituted pyrazolo[3,4-c]- and pyrazolo[4, 3-c]quinolines and -isoquinolines from 4- and 5-aryl-substituted 1-benzyloxypyrazoles.

1-Hydroxypyrazolo[3,4-c]quinoline (22), 1-hydroxypyrazolo[4, 3-c]quinoline (21), 1-hydroxypyrazolo[3,4-c]isoquinoline (20), and 1-hydroxypyrazolo[4,3-c]isoquinoline (19) were prepared from 1-benzyloxypyrazole (6), establishing the pyridine B-ring in the terminal step. The pyridine ring of pyrazoloquinolines 14 and 18 was formed via cyclization of a formyl group at C-4 or C-5 and an amino group of a 2-aminophenyl substituent at C-5 or C-4 in 1-benzyloxypyrazole. The pyridine ring of pyrazoloisoquinolines 5 and 9 was created via cyclization of a formyl group in a 2-formylphenyl substituent at C-4 or C-5 with an iminophosphorane group installed at C-5 or C-4 of 1-benzyloxypyrazole by lithiation followed by reaction with tosyl azide and then with tributylphoshine utilizing the Staudinger/aza-Wittig protocol.

Accumulation of the anandamide precursor and other N-acylethanolamine phospholipids in infant rat models of in vivo necrotic and apoptotic neuronal death.

It has been demonstrated that the endogenous cannabinoid receptor ligand, anandamide, and other N-acylethanolamines (NAEs), accumulate during neuronal injury in vitro, a process that may be linked to the neuroprotective effects of NAEs. The crucial step for generation of NAEs is the synthesis of the corresponding precursors, N-acylethanolamine phospholipids (NAPEs). However, it is unknown whether this key event for NAE formation is regulated differently in the context of insults causing necrotic or apoptotic neuronal death.

Effects of interactions between powder particle size and binder viscosity on agglomerate growth mechanisms in a high shear mixer.

A study was performed in order to elucidate the effects of the interactions between powder particle size and binder viscosity on the mechanisms involved in agglomerate formation and growth. Calcium carbonates having mean particle sizes in the range of 5-214 microm and polyethylene glycols having viscosities in the range of approximately 50-100000 mPas were melt agglomerated in a high shear mixer. Agglomerate growth by nucleation and coalescence was found to dominate when agglomerating small powder particles and binders with a low viscosity.

Direct estimation of the in vivo dissolution of spironolactone, in two particle size ranges, using the single-pass perfusion technique (Loc-I-Gut) in humans.

Aim: The objective of this in vivo dissolution study was to investigate the usefulness of the Loc-I-Gut technique for differentiating between the in vivo dissolution rate of two particle sizes of spironolactone, and to compare these in vivo results with corresponding in vitro data.

Methods: The study included six volunteers, and consisted of three sequential parts (I, II, III). In parts I and III the in vivo dissolution was measured directly by perfusing a semi-open segment in the proximal jejunum.

N-Acylethanolamines and precursor phospholipids - relation to cell injury.

The present review focuses on the relationship between formation of N-acylethanolamine phospholipids (NAPEs) and N-acyletransferase (NAEs) catalyzed by N-acyltranferase and NAPE-hydrolyzing phospholipase D, respectively, and cell injury in tissues like brain, heart, and testis. A number of mechanisms are proposed by which these two groups of lipids may have cytoprotective properties. The mechanisms may involve activation of cannabinoid receptors, as well as non-receptor-mediated effects such as stabilization of membrane bilayers, antioxidant mechanisms, inhibition of calcium leakage from mitochondria, and direct inhibition of ceramidase.

NMR characterisation and transdermal drug delivery potential of microemulsion systems.

The purpose of this study was to investigate the influence of structure and composition of microemulsions (Labrasol/Plurol Isostearique/isostearylic isostearate/water) on their transdermal delivery potential of a lipophilic (lidocaine) and a hydrophilic model drug (prilocaine hydrochloride), and to compare the drug delivery potential of microemulsions to conventional vehicles. Self-diffusion coefficients determined by pulsed-gradient spin-echo NMR spectroscopy and T(1) relaxation times were used to characterise the microemulsions. Transdermal flux of lidocaine and prilocaine hydrochloride through rat skin was determined in vitro using Franz-type diffusion cells.

CGRP and adrenomedullin receptor populations in human cerebral arteries: in vitro pharmacological and molecular investigations in different artery sizes.

The aim of the present study was to determine functional and molecular characteristics of receptors for calcitonin gene-related peptide (CGRP) and adrenomedullin in three different diameter groups of lenticulostriate arteries. Furthermore, the presence of perivascular neuronal sources of CGRP was evaluated in these arteries. In the functional studies, in vitro pharmacological experiments demonstrated that both CGRP and adrenomedullin induce alpha-CGRP-(8-37) sensitive vasodilation in artery segments of various diameters.

Studies of the structure of insulin fibrils by Fourier transform infrared (FTIR) spectroscopy and electron microscopy.

Fibril formation (aggregation) of insulin was investigated in acid media by visual inspection, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. Insulin fibrillated faster in hydrochloric acid than in acetic acid at elevated temperatures, whereas the fibrillation tendencies were reversed at ambient temperatures. Electron micrographs showed that bovine insulin fibrils consisted of long fibers with a diameter of 5 to 10 nm and lengths of several microns.

Pharmacological and functional characterization of astrocytic GABA transport: a short review.

GABA neurotransmission is terminated by high affinity transport mediated by a number of carriers on neurons and astrocytes. So far four different carriers have been cloned and their cellular distribution has been partly worked out. It is generally believed that GAT-1 (mouse homologue GAT1) is the quantitatively most important of the transporters and it is primarily present on GABAergic neurons but also to some extent on astrocytes.

Resolution, configurational assignment, and enantiopharmacology of 2-amino-3-[3-hydroxy-5-(2-methyl-2H- tetrazol-5-yl)isoxazol-4-yl]propionic acid, a potent GluR3- and GluR4-preferring AMPA receptor agonist.

We have previously shown that (RS)-2-amino-3-[3-hydroxy-5-(2-methyl-2H-tetrazol-5-yl)isoxazol -4-yl] propionic acid (2-Me-Tet-AMPA) is a selective agonist at (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors, markedly more potent than AMPA itself, whereas the isomeric compound 1-Me-Tet-AMPA is essentially inactive. We here report the enantiopharmacology of 2-Me-Tet-AMPA in radioligand binding and cortical wedge electrophysiological assay systems, and using cloned AMPA (GluR1-4) and kainic acid (KA) (GluR5, 6, and KA2) receptor subtypes expressed in Xenopus oocytes. 2-Me-Tet-AMPA was resolved using preparative chiral HPLC.

Various nitric oxide donors protect chick embryonic neurons from cyanide-induced apoptosis.

The discovery of numerous biochemical effects of cyanide not directly related to the inhibition of the respiratory chain, including the involvement of apoptosis, has challenged the basis of traditional antidote treatment, which primarily depends on nitrite-induced conversion of hemoglobin into methemoglobin, releasing the blockade of cytochrome c oxidase by high-affinity binding of cyanide as cyanmethemoglobin. The fact that amyl nitrite has antidotal effects not related to methemoglobin formation has unfolded new mechanism of actions of nitrites including release of nitric oxide (NO). In this study, we characterized the effect of various NO donor compounds on cyanide-induced cell death in cultured chick embryonic neurons.

Modification of in vitro drug release rate from oily parenteral depots using a formulation approach.

Rate constants for transfer of naproxen and lidocaine from different oils and oil mixtures to aqueous buffer, pH 6.00, were determined using the rotating dialysis cell. Significantly different first-order rate constants related to attainment of equilibrium, k(obs), were derived depending on the type of oil/oil mixtures used in the release experiments.

Assessment of rate of drug release from oil vehicle using a rotating dialysis cell.

The rate constants for transfer of model compounds (naproxen and lidocaine) from oily vehicle (Viscoleo) to aqueous buffer phases were determined by use of the rotating dialysis cell. Release studies were done for the partly ionized compounds at several pH values. A correlation between the overall first-order rate constant related to attainment of equilibrium, k(obs), and the pH-dependent distribution coefficient, D, determined between oil vehicle and aqueous buffer was established according to the equation: logk(obs)=-0.

Rational selection of antisense oligonucleotide sequences.

The purpose of this review is to identify rational selection procedures for the identification of optimal antisense oligonucleotide sequences. The review is firstly focused on how to find optimal hybridization sites, and secondly on how to select sequences that bind to structured RNA. The methods reviewed range from the more empirical testing of large numbers of mRNA complementary sequences to the more systematic techniques, i.

Impact of particle density and initial volume on mathematical compression models.

In the calculation of the coefficients of compression models for powders either the initial volume or the particle density is introduced as a normalising factor. The influence of these normalising factors is, however, widely different on coefficients derived from the Kawakita, Walker and Heckel equations. The problems are illustrated by investigations on compaction profiles of 17 materials with different molecular structures and particle densities.

A new structural class of subtype-selective inhibitor of cloned excitatory amino acid transporter, EAAT2.

We have studied the pharmacological effects of (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) and the enantiomers of (RS)-2-amino-3-(3-hydroxy-1,2, 5-thiadiazol-4-yl)propionic acid (TDPA) on cloned human excitatory amino acid transporter subtypes 1, 2 and 3 (EAAT1-3) expressed in Cos-7 cells. Whereas AMPA and (R)-TDPA were both inactive as inhibitors of [3H]-(R)-aspartic acid uptake on all three EAAT subtypes, (S)-TDPA was shown to selectively inhibit uptake by EAAT2 with a potency equal to that of the endogenous ligand (S)-glutamic acid. (S)-TDPA thus represents a new structural class of EAAT2 inhibitor that will serve as a lead for the design of EAAT selective inhibitors.

Intranasal absorption of buprenorphine--in vivo bioavailability study in sheep.

The bioavailability of buprenorphine, HCl (BPP) in sheep after nasal administration of two formulations has been studied. 0.9 mg BPP in 150 microl was administered nasally and compared to 0.

Absolute configuration and antiprotozoal activity of minquartynoic acid.

Minquartynoic acid (1) was isolated as an antimalarial and antileishmanial constituent of the Peruvian tree Minquartia guianensis and its absolute configuration at C-17 established to be (+)-S through conversion to the known (+)-(S)-17-hydroxystearic acid (2) and confirmed using Mosher's method.

HPLC analysis of the seasonal and diurnal variation of iridoids in cultivars of Antirrhinum majus.

In this paper we show the seasonal and diurnal variation in the content of the four iridoids found in cultivars of Antirrhinum majus, antirrhinoside, antirrhide, 5-glucosyl-antirrhinoside and linarioside. The seasonal variation in total iridoid content showed a marked bimodal distribution with high total values (around 100mg/g dry matter) early and late in the season and a very low content of all iridoids coinciding with the onset of flowering at the beginning of August. The relative contribution of antirrhinoside was significantly higher before flowering than after bud break.

Synthesis of epimers of L-cyclopentenylglycine using enzymatic resolution.

Both epimers of the naturally occurring nonproteinogenic amino acid L-cyclopentenylglycine, (2S,1'S)- and (2S, 1'R)-2-(cyclopent-2'-enyl)glycine, were obtained via a procedure involving condensation of 3-chlorocyclopentene with diethyl acetylaminomalonate, deethoxycarbonylation, chromatographic separation of the resulting two pairs of enantiomers, and enzymatic resolution of the racemates employing enantioselective hydrolysis of the ethyl ester group with alpha-chymotrypsin. The method was used for preparation of (13)C-labeled compounds of interest for biosynthetic tracer experiments. Enantiomeric purity of the products was determined by chiral HPLC on a Crownpak CR(+) column.

Agonist discrimination between AMPA receptor subtypes.

The lack of subtype-selective compounds for AMPA receptors (AMPA-R) led us to search for compounds with such selectivity. Homoibotenic acid analogues were investigated at recombinant GluR1o, GluR2o(R), GluR3o and GluR1o + 3o receptors expressed in Sf9 insect cells and affinities determined in [3H]AMPA radioligand binding experiments. (S)-4-bromohomoibotenic acid (BrHIBO) exhibited a 126-fold selectivity for GluR1o compared to GluR3o.