Improved water absorption behaviour of experimental hydrophilic vinyl polysiloxane (VPS) impression materials incorporating a crosslinking agent and a novel surfactant.

Objectives: To study the effects of incorporating a further crosslinking agent and a novel surfactant on the water absorption behaviour of experimental VPS impression materials.

Methods: Part 1: The water uptake behaviour of Aquasil-Ultra-Monophase (AqM) was studied gravimetrically in three media (DW, 1%NaOCl and Perform ID), at 23 °C and 37 °C, over a period of one and four-months (n = 5) to gain information on long-term immersion. Part 2: Five experimental materials were formulated: Exp-I and II as hydrophobic and Exp-III-V as hydrophilic, containing an additional cross-linking agent (TFDMSOS) and Rhodasurf CET-2 surfactant.

The effects of cross-linking agent and surfactant on the tear strength of novel vinyl polysiloxane impression materials.

Objectives: To formulate experimental hydrophobic and hydrophilic vinyl polysiloxane (VPS) impression materials ab initio, comprising a novel cross-linking agent, tetra-functional (dimethylsilyl) orthosilicate (TFDMSOS), and a non-ionic surfactant, Rhodasurf CET-2 (ethoxylatedcetyl-oleyl alcohol), and to investigate their effects on tear strength (TS).

Methods: Five experimental formulations (Exp I-V) were prepared and compared with three medium bodied commercial VPS impression materials (Aq M, Elt M, Extr M). Tear test was performed on trouser test specimens (n=12 per material), at four time points (immediately, 24, 72 and 168 hours after setting).

Experimental hydrophilic vinyl polysiloxane (VPS) impression materials incorporating a novel surfactant compared with commercial VPS.

Objectives: To formulate experimental hydrophilic (Exp) VPS impression materials incorporating a novel surfactant (Rhodasurf CET-2), and to compare their contact angles (CAs) with commercial materials, before/after disinfection.

Methods: CAs were measured immediately after setting and after disinfection (1% NaOCl; 30min and 24h), together with their change whilst a droplet remained on the materials surface (over 10, 20, 30 60 and 120s), on three commercial (Aquasil Ultra-Monophase [Aq M], Elite HD-Monophase [Elt M], Extrude Medium-bodied [Extr M]) and four experimental (Exp I-IV) materials, using the Drop Shape Analysis 100 technique. The results were compared statistically.

A study to investigate and compare the physicomechanical properties of experimental and commercial temporary crown and bridge materials.

Objectives: To develop two experimental temporary crown and bridge materials with improved physicomechanical properties.

Methods: Commercial materials: Trim (TR, monomethacrylate, Bosworth) and Quicktemp2 (QT, dimethacrylate, Schottlander).

Experimental Materials: isobutyl methacrylate/poly(ethyl methacrylate) (IBMA/PEM) and n-butyl methacrylate/PEM (nBMA/PEM), both monomethacrylates.

Modification of pH Conferring Virucidal Activity on Dental Alginates.

To formulate an alginate dental impression material with virucidal properties, experimental alginate dental impression materials were developed and the formulations adjusted in order to study the effect on pH profiles during setting. Commercially available materials served as a comparison. Eight experimental materials were tested for antiviral activity against Herpes Simplex Virus type 1 (HSV-1).

A novel fluorine-18 β-fluoroethoxy organophosphate positron emission tomography imaging tracer targeted to central nervous system acetylcholinesterase.

Radiosynthesis of a fluorine-18 labeled organophosphate (OP) inhibitor of acetylcholinesterase (AChE) and subsequent positron emission tomography (PET) imaging using the tracer in the rat central nervous system are reported. The tracer structure, which contains a novel β-fluoroethoxy phosphoester moiety, was designed as an insecticide-chemical nerve agent hybrid to optimize handling and the desired target reactivity. Radiosynthesis of the β-fluoroethoxy tracer is described that utilizes a [(18)F]prosthetic group coupling approach.

Delivery of macromolecules across oral mucosa from polymeric hydrogels is enhanced by electrophoresis (iontophoresis).

Objective: To develop polymeric hydrogel delivery systems for iontophorseis transfer of large molecules across buccal (porcine) mucosa.

Methods: Three hydrogels (PVA, HPMC and PVA/HPMC) were prepared as stable gels (7 mm diameter/1.5 mm thick).

Microwave accelerated synthesis of isoxazole hydrazide inhibitors of the system xc- transporter: Initial homology model.

Microwave accelerated reaction system (MARS) technology provided a good method to obtain selective and open isoxazole ligands that bind to and inhibit the Sxc- antiporter. The MARS provided numerous advantages, including: shorter time, better yield and higher purity of the product. Of the newly synthesized series of isoxazoles the salicyl hydrazide 6 exhibited the highest level of inhibitory activity in the transport assay.

Electrically induced transport of macromolecules through oral buccal mucosa.

Objective: To investigate the feasibility of iontophoretic delivery of large molecules across buccal mucosa, and to establish its potential for enhanced drug delivery.

Methods: Qualitative (6h) and quantitative (8 and 36 h) assessment of porcine buccal mucosa, using a diffusion cell in vitro model, was carried out by fluorescent microscopy and UV/Vis spectroscopy respectively, with four fluorescently-labeled model species (3 and 10 kDa dextrans, 12 kDa parvalbumin and 66 kDa bovine serum albumin, BSA). Passive and iontophoresis parameters were obtained.

The interaction of various liquids with long-term denture soft lining materials.

Objectives: To study the uptake of liquids, representative of those encountered orally, by long-term denture soft lining materials, and analyze the data in terms of appropriate theories.

Methods: Four proprietary and one experimental soft lining material were investigated, and the weight change presented as a function of time in both aqueous and organic fluids over the course of a year. A separate experiment determined the equilibrium swelling in ethanol of poly(ethyl methacrylate) and poly(methyl methacrylate).

Some aspects of the formulation of alginate dental impression materials--setting characteristics and mechanical properties.

Objective: To study the role of the various components of alginate dental impression materials.

Methods: Experimental materials were formulated and their physical properties characterized and compared to commercially available counterparts (Neocolloid, Palgat Plus and Blueprint Cremix). Properties examined were: dimensional stability and weight change in water and artificial saliva; setting behavior; Shore A hardness and tear energy.

The effect of disinfecting solutions on the dimensional stability of dental alginate impression materials.

Objectives: Dimensional changes occur in set dental alginate impression materials when immersed in disinfecting solutions. In this contribution the dimensional changes of two alginates in two disinfecting solutions, and for two specimen thicknesses, have been studied. The results were analyzed theoretically.

An experimental and theoretical study of the effect of sample thickness on the Shore hardness of elastomers.

Objective: The Shore hardness test is a quick and convenient way to measure hardness of elastomers. The test specifies that the specimen should be at least 6mm thick; however, published work in the literature indicates that workers often use much thinner samples. The aim of this study was to investigate the effect of thickness on the measured hardness of a range of dental elastomers and develop a theoretical relationship to predict the effect.

Inhibition of acetylcholinesterase by chromophore-linked fluorophosphonates.

Fluorophosphonate (FP) head groups were tethered to a variety of chromophores (C) via a triazole group and tested as FPC inhibitors of recombinant mouse (rMoAChE) and electric eel (EEAChE) acetylcholinesterase. The inhibitors showed bimolecular inhibition constants (k(i)) ranging from 0.3 x 10(5)M(-1)min(-1) to 10.

The relationship between Shore hardness of elastomeric dental materials and Young's modulus.

Objectives: Hardness of elastomers can be directly related to Young's modulus, a relationship that was investigated in detail by Gent in a paper in 1958. The aim of this study was to test this relationship for 13 dental elastomers (12 silicone and 1 polyether) using the equation derived by Gent and one from BS 903 (1950) that accounts for departures at low values.

Methods: The dental elastomers were subjected to tensile testing and Shore A scale hardness measurements.

Assessment of the roles of serines 5.43(239) and 5.46(242) for binding and potency of agonist ligands at the human serotonin 5-HT2A receptor.

We assessed the relative importance of two serine residues located near the top of transmembrane helix 5 of the human 5-HT(2A) receptor, comparing the wild type with S5.43(239)A or S5.46(242)A mutations.

Molecular interaction of serotonin 5-HT2A receptor residues Phe339(6.51) and Phe340(6.52) with superpotent N-benzyl phenethylamine agonists.

Experiments were conducted to examine the molecular basis for the high affinity and potency of a new class of 5-HT(2A) receptor agonists, N-benzyl phenethylamines. Competition binding assays at several serotonin receptors confirmed that an N-arylmethyl substitution was necessary for affinity increases up to 300-fold over simple N-alkyl homologs, as well as enhanced selectivity for 5-HT(2A) versus 5-HT(2C) and 5-HT(1A) receptors. PI hydrolysis functional assays confirmed that these N-benzyl phenethylamines are potent and highly efficacious agonists at the rat 5-HT(2A) receptor.

1-Aminomethylbenzocycloalkanes: conformationally restricted hallucinogenic phenethylamine analogues as functionally selective 5-HT2A receptor agonists.

A series of conformationally restricted analogues of the hallucinogenic phenethylamine 1 (2,5-dimethoxy-4-bromophenethylamine, 2C-B) was synthesized to test several hypotheses concerning the bioactive conformation of phenethylamine ligands upon binding to the 5-HT(2A) receptor. These benzocycloalkane analogues were assayed for their receptor binding affinity and ability to activate downstream signaling pathways, and one exceptional compound was selected for testing in an in vivo drug discrimination model of hallucinogenesis. All compounds were examined in silico by virtual docking into a homology model of the 5-HT(2A) receptor.

C-(4,5,6-trimethoxyindan-1-yl)methanamine: a mescaline analogue designed using a homology model of the 5-HT2A receptor.

A conformationally restricted analogue of mescaline, C-(4,5,6-trimethoxyindan-1-yl)-methanamine, was designed using a 5-HT(2A) receptor homology model. The compound possessed 3-fold higher affinity and potency than and efficacy equal to that of mescaline at the 5-HT(2A) receptor. The new analogue substituted fully for LSD in drug discrimination studies and was 5-fold more potent than mescaline.

Differential phospholipase C activation by phenylalkylamine serotonin 5-HT 2A receptor agonists.

Experiments compared a series of phenethylamine hallucinogens with their phenylisopropylamine analogues for binding affinity and ability to stimulate serotonin 5-HT 2A receptor-mediated hydrolysis of phosphatidyl inositol in cells expressing cloned rat and human 5-HT 2A receptors. The (+/-)phenylisopropylamine analogues had significantly higher intrinsic activities for 5-HT 2A receptor-mediated hydrolysis of phosphatidyl inositol compared to their phenethylamine analogues. With respect to the effects of the stereochemistry of the phenylisopropylamines, those with the (R) absolute configuration at the alpha carbon had higher intrinsic activities for hydrolysis of phosphatidyl inositol in a cell line expressing the human 5-HT 2A receptor compared to those with the (S) absolute configuration.

NMR imaging of the diffusion of water at 310 K into semi-IPNs of PEM and poly(HEMA-co-THFMA) with and without chlorhexidine diacetate.

Magnetic resonance imaging has been used to monitor the diffusion of water at 310 K into a series of semi-IPNs of poly(ethyl methacrylate), PEM, and copolymers of 2-hydroxyethyl methacrylate, HEMA, and tetrahydrofurfuryl methacrylate, THFMA. The diffusion was found to be well described by a Fickian kinetic model in the early stages of the water sorption process, and the diffusion coefficients were found to be slightly smaller than those for the copolymers of HEMA and THFMA, P(HEMA-co-THFMA), containing the same mole fraction of HEMA in the matrix. A second stage sorption process was identified in the later stage of water sorption by the PEM/PTHFMA semi-IPN and for the systems containing a P(HEMA-co-THFMA) component with a mole fraction HEMA of 0.

Use of prepolymerized cement spacers to augment the femoral component in revision total knee arthroplasty: a clinical outcome report and laboratory experiment.

A technique for revision total knee arthroplasty managing posterior femoral condylar bone loss with prepolymerized polymethyl methacrylate cement spacers as augments to the femoral component is described in 10 consecutive cases. The maximum follow-up time is 63 months. This method allows for maintenance of the posterior joint line, which in turn facilitates appropriate flexion-extension gap balancing.