Synthesis, in vitro and in vivo biological evaluation of substituted 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones as new potent anticancer agents.

A small library of 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones has been synthesized and screened according to protocols available at the National Cancer Institute (NCI). Some derivatives were potent antiproliferative agents, showing GI values in the nanomolar range. Remarkably, when most active compounds against leukemia cells were tested in human peripheral blood lymphocytes from healthy donors, were 100-200 times less cytotoxic.

Natriuretic peptide activation of extracellular regulated kinase 1/2 (ERK1/2) pathway by particulate guanylyl cyclases in GH3 somatolactotropes.

The natriuretic peptides, Atrial-, B-type and C-type natriuretric peptides (ANP, BNP, CNP), are regulators of many endocrine tissues and exert their effects predominantly through the activation of their specific guanylyl cyclase receptors (GC-A and GC-B) to generate cGMP. Whereas cGMP-independent signalling has been reported in response to natriuretic peptides, this is mediated via either the clearance receptor (Npr-C) or a renal-specific NPR-Bi isoform, which both lack intrinsic guanylyl cyclase activity. Here, we report evidence of GC-B-dependent cGMP-independent signalling in pituitary GH3 cells.

De novo computer-aided design of novel antiviral agents.

Computer-aided drug design techniques have become an integral part of the drug discovery process. In particular, de novo methodologies can be useful to identify putative ligands for a specific target relying only on the structural information of the target itself. Here we discuss the basic de novo approaches available and their application in antiviral drug design.

Density functional theory calculation of cyclic carboxylic phosphorus mixed anhydrides as possible intermediates in biochemical reactions: implications for the Pro-Tide approach.

Cyclic acyl phosphoramidates (CAPAs) are important components in several fundamental biological reactions such as protein synthesis and phosphorylation. These structures are particularly interesting in the nucleotide pro-drug approach, Pro-Tide, since they are putative intermediates in one of the hydrolysis steps required for activation. The central role played by the amino acid carboxylate function suggests first the formation of a cyclic mixed phosphorus anhydride, rapidly followed by water attack.

Towards a thermodynamic definition of efficacy in partial agonism: The thermodynamics of efficacy and ligand proton transfer in a G protein-coupled receptor of the rhodopsin class.

The thermodynamic binding profiles of agonist and antagonist complexes of the 4-hydroxypropanolamine partial agonist, prenalterol, on the chronotropic adrenergic response in guinea-pig right atria were determined over a 15 °C temperature range. The tissue response was compared with data on the ethanolamine agonist, isoprenaline, given by binding studies in a number of rat tissues. Utilising the residue conservatism surrounding the known active conformers bound to either of two aspartate residues (α-helices II, III) in both receptors (β(1), β(2)) and species (guinea-pig, rat and human), no significant deformation in the extended side chain could be found in prenalterol's agonist binding compared to isoprenaline.

Discovery of a novel HCV helicase inhibitor by a de novo drug design approach.

Herein we report a successful application of a computer-aided design approach to identify a novel HCV helicase inhibitor. A de novo drug design methodology was used to generate an initial set of structures that could potentially bind to a putative binding site. Further structure refinement was carried out through docking a series of focused virtual libraries.

Delivery strategies for siRNA-mediated gene silencing.

RNA interference (RNAi) represents a promising new gene silencing technology for functional genomics and a potential therapeutic strategy for a variety of genetic diseases. RNAi involves the targeted post-transcriptional degradation of messenger RNA thereby inhibiting the synthesis of the desired protein. This effectively leads to silencing of gene expression.

Sustained polymeric delivery of gene silencing antisense ODNs, siRNA, DNAzymes and ribozymes: in vitro and in vivo studies.

Small interfering RNA (siRNA), antisense oligonucleotides (ODNs), ribozymes and DNAzymes have emerged as sequence-specific inhibitors of gene expression that may have therapeutic potential in the treatment of a wide range of diseases. Due to their rapid degradation in vivo, the efficacy of naked gene silencing nucleic acids is relatively short lived. The entrapment of these nucleic acids within biodegradable sustained-release delivery systems may improve their stability and reduce the doses required for efficacy.

The design and exogenous delivery of siRNA for post-transcriptional gene silencing.

RNA interference (RNAi) is a natural cellular process that effects post-transcriptional gene silencing in eukaryotic systems. Small interfering RNA (siRNA) molecules are the key intermediaries in this process which when exogenously administered can inhibit or "silence" the expression of any given target gene. Thus, siRNA molecules hold great promise as biological tools and as potential therapeutic agents for targeted inhibition of disease-causing genes.

Gene silencing nucleic acids designed by scanning arrays: anti-EGFR activity of siRNA, ribozyme and DNA enzymes targeting a single hybridization-accessible region using the same delivery system.

Gene silencing nucleic acids such as ribozymes, DNA enzymes (DNAzymes), antisense oligonucleotides (ODNs), and small interfering (si)RNA rely on hybridization to accessible sites within target mRNA for activity. However, the accurate prediction of hybridization accessible sites within mRNAs for design of effective gene silencing reagents has been problematic. Here we have evaluated the use of scanning arrays for the effective design of ribozymes, DNAzymes and siRNA sequences targeting the epidermal growth factor receptor (EGFR) mRNA.

Toxicogenomics of non-viral vectors for gene therapy: a microarray study of lipofectin- and oligofectamine-induced gene expression changes in human epithelial cells.

Of the non-viral vectors, cationic lipid (CL) formulations are the most widely studied for the delivery of genes, antisense oligonucleotides and gene silencing nucleic acids such as small interfering RNAs. However, little is known about the impact of these delivery systems on global gene expression in target cells. In an attempt to study the geno-compatibility of CL formulations in target cells, we have used microarrays to examine the effect of Lipofectin and Oligofectamine on the gene expression profiles of human A431 epithelial cells.

Enantioselectivity of some 1-[(benzofuran-2-yl) phenylmethyl] imidazoles as aromatase (P450AROM) inhibitors.

The enantioselectivity ratio ((+)-:(-)-forms) of three substituted 1-[(benzofuran-2-yl) phenylmethyl] imidazoles as inhibitors of aromatase (P450AROM) was 2.16, 12.3 and 1.

The inhibition of phagocytosis of respirable microspheres by alveolar and peritoneal macrophages.

Respirable poly(lactic co-glycolic acid) (PLGA) microspheres (2-3 microm diameter), were fabricated as a model drug delivery system whose uptake by macrophages could be quantified by fluorescent activated cell sorting. The microspheres exhibited minimal release of the entrapped flourophore (rhodamine B) and thus avoided possible fluid phase uptake of the flourophore. Externally bound microspheres were removed from the cell membrane by acid washing.

Water quantitatively induces the mucoadhesion of liquid crystalline phases of glyceryl monooleate.

The possible role of water in the mucoadhesion phenomenon exhibited by the liquid crystalline phases of glyceryl monooleate was investigated using an in-vitro tensile strength technique. The mucoadhesion of the liquid crystalline phases of glyceryl monooleate was found to occur following uptake of water. The mucoadhesive force of the cubic phase was consistent since it is not capable of taking up additional water.

ATR-FTIR spectroscopic investigations on the effect of solvents on the permeation of benzoic acid and salicylic acid through silicone membranes.

The effect of a series of alcohols on the permeation of salicylic acid (SA) and benzoic acid (BA) through silicone membrane was evaluated, using Franz-type diffusion cells. Although permeants were applied at the same thermodynamic activity in all vehicles, the resulting fluxes were found to differ significantly. This was a consequence of the interactions between the vehicles and the membrane.

An investigation of the solubility of various compounds in the hydrofluoroalkane propellants and possible model liquid propellants.

The aims of this study were to investigate descriptive parameters that may predict the solubility of compounds in the hydrofluoroalkane (HFA) propellants and to identify a model HFA propellant that is liquid at room temperature and atmospheric pressure. The solubility of 32 and 20 compounds chosen to give a wide range of physicochemical properties in HFA-134a and HFA-227, respectively, was measured. The Fedors solubility parameter and a computed log octanol water partition coefficient (CLOGP) were compared with the compounds' solubility in the HFA propellants.

The selection of non-steroidal anti-inflammatory agents for dermal delivery.

An analysis has been conducted to show how the penetration of a selection of non-steroidal anti-inflammatory agents (NSAIDs) through the skin may be predicted. The calculations are based on physicochemical parameters that can be predicted using commercially available software. Where available the predictions compare favourably with the literature values.

pH, pK(a) and dermal delivery.

The effect of pH on the permeation of ibuprofen and lignocaine through human skin has been modelled using a modification to the equation derived by Potts and Guy, which is normally applied to unionized entities. The results show that permeation is related to the distribution coefficient. The physicochemical properties have been predicted ab initio using commercially available software and compared to literature values.

Improved nasal bioavailability of FITC-dextran (Mw 4300) from mucoadhesive microspheres in rabbits.

The nasal bioavailability of fluorescein isothiocyanate-dextran (FITC-dextran) (Mw = 4300) encapsulated in non-mucoadhesive and mucoadhesive microspheres in New Zealand White rabbits was investigated. FITC-dextran was administered nasally encapsulated in carbopol 934P, chitosan and lactose microspheres and the bioavailability compared to intravenous administration of FITC-dextran solution. Administration of FITC-dextran as carbopol microspheres produced a significantly greater bioavailability (33%) than after administration as chitosan (13%) and non-mucoadhesive rapidly dissolving control lactose microspheres (9%).

Epidermal permeability-penetrant structure relationships: 4, QSAR of permeant diffusion across human stratum corneum in terms of molecular weight, H-bonding and electronic charge.

Principal components analysis (PCA) and multivariate regression analysis (MRA) are used to assess the predictors of permeant diffusion across human stratum corneum. Log(D/h), was estimated from logk(p)+0.024-0.

Microcalorimetry does not predict the cellular phagocytosis of latex microspheres.

Current literature highlights the potential suitability of microcalorimetry for the investigation of cell-drug interactions. Previous work using bacteria or antigens derived from infectious organisms yielded conclusions that heat production is a quantitative means of measuring phagocytosis. In this study we evaluated the potential of flow-through microcalorimetry as a method of quantifying the phagocytosis of microsphere particulates.

Prodrug to probe solution HFA pMDI formulation and pulmonary esterase activity.

A novel salbutamol prodrug was synthesised. Solubility in HFA-134a and susceptibility to rat lung homogenate, blood and plasma esterase enzymes were investigated. Whereas salbutamol had a very low solubility in HFA-134a, the prodrug was found to be miscible in all proportions.

Effect of cellulose polymers on supersaturation and in vitro membrane transport of hydrocortisone acetate.

A systematic investigation on the influence of two cellulose polymers, methyl cellulose (MC) and hydroxypropyl cellulose (HPMC) on supersaturation and permeation of hydrocortisone acetate (HA) is reported. Diffusion of HA from a 0.5% Carbopol gel across a model silicone membrane was investigated using the Franz-cell technique.

Do alpha2-adrenoceptors play an integral role in the antinociceptive mechanism of action of antidepressant compounds?

Antidepressants are analgesic in the absence or presence of depression. The underlying mechanisms probably involve a complex interplay between several neurotransmitter systems and neuroreceptors. Alpha-adrenoceptors play an important role in pain processing and alpha2-adrenoceptor agonists have been used in clinical pain management so we have investigated whether alpha-adrenoceptor sub-types mediate the antinociceptive activity of antidepressants.

Passive enhancement strategies in topical and transdermal drug delivery.

The skin has an extremely good barrier function and to improve topical bioavailability it is usually necessary to employ enhancement strategies. Optimization of the applied formulation can improve release to the skin and the use of supersaturation achieves this objective. However, supersaturated states are inherently unstable.