Motivations and perceived influences on rural and urban general practitioners when prescribing conventional non-steroidal anti-inflammatory drugs or COX-2 inhibitors

Background and objective: Prescribers in rural and remote locations perceive that there are different influences on their prescribing compared with those experienced by urban prescribers. The aim of this study was to compare the motivations and perceived influences on general practitioners (GPs) when prescribing COX-2 inhibitors rather than conventional non-steroidal anti-inflammatory drugs (NSAIDs) between rural and urban-based GPs in Queensland, Australia. Methods: A questionnaire was administered to two geographically distinct groups of GPs, one urban (n = 67) and one rural (n = 67), investigating the reasons that the GP would prescribe a COX-2 inhibitor rather than a conventional NSAID or vice versa and also focusing on patients requesting a prescription for a COX-2 inhibitor. Results and discussion: A 51% response rate (n = 68) was achieved. The difference between the rural and the urban GPs was that the urban GPs were more likely to perceive that they were influenced to prescribe COX-2 inhibitors by their patients' knowledge of these new (at the time) drugs. GPs in both the rural and urban areas perceived the COX-2 selective inhibitors to be safer than conventional NSAIDs, and that there was little difference in terms of efficacy between the two drug classes. However, GPs from both of the study areas stated that conventional NSAIDs were preferred over COX-2 selective inhibitors, primarily due to their expense, if their patients were not at risk for developing a GI bleed. Conclusion: The motivations and perceived influences to prescribe a COX-2 inhibitor in rural and in urban areas of Queensland, Australia were very similar. Almost all surveyed GPs in rural and urban areas had patients request a prescription, or enquire about the COX-2 inhibitors. Urban GPs were more likely to feel pressured to prescribe a COX-2 inhibitor than their rural counterparts, agreeing with other research which found that patient pressure to prescribe appears to be greater in urban general practice.

Inhibitors of cholesteryl ester transfer protein - a step forward in the treatment of coronary artery disease?

Although the LDL cholesterol-lowering statins have reduced the mortality and morbidity associated with coronary artery disease (CAD), considerable mortality and morbidity remains. Increasing HDL cholesterol levels is associated with reduced CAD mortality and morbidity. In healthy subjects with mild dyslipidemia, treatment with JTT-705 decreased cholesteryl ester transfer protein (CETP) activity, increased HDL cholesterol and decreased LDL cholesterol. Similarly, another CETP inhibitor, torcetrapib, has recently been shown to increase HDL cholesterol by 46%, decrease LDL cholesterol by 8% and have no effect on triglycerides in subjects with HDL cholesterol levels below 1.0 mmol/l. Increasing HDL cholesterol with inhibitors of CETP represents a new approach to dyslipidemia that requires further investigation, especially in patients with CAD.

Cardiac chymase: pathophysiological role and therapeutic potential of chymase inhibitors

On release from cardiac mast cells, alpha-chymase converts angiotensin I (Ang I) to Ang II. In addition to Ang II formation, alpha-chymase is capable of activating TGF-beta 1 and IL-1 beta, forming endothelins consisting of 31 amino acids, degrading endothelin-1, altering lipid metabolism, and degrading the extracellular matrix. Under physiological conditions the role of chymase in the mast cells of the heart is uncertain. In pathological situations, chymase may be secreted and have important effects on the heart. Thus, in animal models of cardiomyopathy, pressure overload, and myocardial infarction, there are increases in both chymase mRNA levels and chymase activity in the heart. In human diseased heart homogenates, alterations in chymase activity have also been reported. These findings have raised the possibility that inhibition of chymase may have a role in the therapy of cardiac disease. The selective chymase inhibitors developed to date include TY-51076, SUN-C8257, BCEAB, NK320, and TEI-E548. These have yet to be tested in humans, but promising results have been obtained in animal models of myocardial infarction, cardiomyopathy, and tachycardia-induced heart failure. It seems likely that orally active inhibitors of chymase could have a place in the treatment of cardiac diseases where injury-induced mast cell degranulation contributes to the pathology.

Receptor binding studies disclose a novel class of high-affinity inhibitors of the Escherichia coli FimH adhesin

Mannose-binding type 1 pili are important virulence factors for the establishment of Escherichia coli urinary tract infections (UTIs). These infections are initiated by adhesion of uropathogenic E. coli to uroplakin receptors in the uroepithelium via the FimH adhesin located at the tips of type 1 pili. Blocking of bacterial adhesion is able to prevent infection. Here, we provide for the first time binding data of the molecular events underlying type 1 fimbrial adherence, by crystallographic analyses of the FimH receptor binding domains from a uropathogenic and a K-12 strain, and affinity measurements with mannose, common mono- and disaccharides, and a series of alkyl and aryl mannosides. Our results illustrate that the lectin domain of the FimH adhesin is a stable and functional entity and that an exogenous butyl alpha- D-mannoside, bound in the crystal structures, exhibits a significantly better affinity for FimH (K-d = 0.15 muM) than mannose (K-d = 2.3 muM). Exploration of the binding affinities of alpha-D-mannosides with longer alkyl tails revealed affinities up to 5 nM. Aryl mannosides and fructose can also bind with high affinities to the FimH lectin domain, with a 100-fold improvement and 15-fold reduction in affinity, respectively, compared with mannose. Taken together, these relative FimH affinities correlate exceptionally well with the relative concentrations of the same glycans needed for the inhibition of adherence of type 1 piliated E. coli. We foresee that our findings will spark new ideas and initiatives for the development of UTI vaccines and anti-adhesive drugs to prevent anticipated and recurrent UTIs.

Anatomy of ethylene-induced floral-organ abscission in Chamelaucium uncinatum (Myrtaceae)

Postharvest abscission of Geraldton waxflower (Chamelaucium uncinatum Schauer) flower buds and flowers is ethylene-mediated. Exposure of floral organs to exogenous ethylene (1 mu L L-1) for 6 h at 20 degrees C induced separation at a morphologically and anatomically distinct abscission zone between the pedicel and. oral tube. Flower buds with opening petals and flowers with a nectiferous hypanthium were generally more responsive to exogenous ethylene than were flower buds enclosed in shiny bracteoles and aged (senescing) flowers. The anatomy of abscission-zone cells did not change at sequential stages of floral development from immature buds to aged flowers. The zone comprised a layer of small, laterally elongated-to-rounded, closely packed and highly protoplasmic parenchyma cells. Abscission occurred at a two- to four-cell-wide separation layer within the abscission zone. The process involved degradation of the middle lamella between separation layer cells. Following abscission, cells on both the proximal and distal faces of the separation layer became spherical, loosely packed and contained degenerating protoplasm. Central vascular tissues within the surrounding band of separation layer cells became torn and fractured. For flower buds, bracteoles that enclose the immature floral tube also separated at an abscission zone. However, this secondary abscission zone appeared less sensitive to ethylene than the primary ( central). oral-tube abscission zone as bracteoles generally only completely abscised when exposed to 10 mu L L-1 ethylene for the longer period of 24 h at 20 degrees C. The smooth surfaces of abscised separation-layer cells suggest that hydrolase enzymes degrade the middle lamella between adjacent cell walls.

An ESR study of the radiolysis of semi-crystalline ethylene-propylene copolymers containing DOP mobilizer

The radiolysis of a poly(ethylene-co-propylene), Elpro, marketed by Thai Polypropylene Co. Ltd for the manufacture of medical goods has been investigated at 77 K. Calcium stearate was blended with the Elpro as a processing aid; and dioctyl phthalate, DOP, was added in various amounts as a radiation stabilizer. The ESR spectra of Elpro and Elpro+Ca were very similar and characterized principally by the presence of PP a-carbon radicals. The spectra of the samples containing DOP were similar to those for Elpro but with an additional narrow singlet arising from DOP radicals. On annealing the irradiated polymers to higher temperatures, the singlet was lost between 250 and 270 K, and at room temperature the principal radicals remaining were allyl radicals. The G-values for radical formation at 77 K for Elpro and Elpro+Ca at 77 K were 3.0 and 3.2, respectively, but incorporation of DOP resulted in lower G-values, ranging from 1.6 to 1.4 for 0.5 and 2.5 phr DOP, respectively.(c) 2005 Wiley Periodicals, Inc.

Structural, mutagenic, and kinetic analysis of the binding of substrates and inhibitors of human phenylethanolamine N-methyltransferase

The X-ray structure of human phenylethanolamine N-methyltransferase (hPNMT) complexed. with its product, S-adenoSyl-L-homocysteine (4), and the most potent inhibitor reported to date, SK&F 64139 (7), was used to identify the residues involved in inhibitor binding. Four of these residues, Va153, Lys57, Glu219 and Asp267, were replaced, in turn, with alanine. All variants had increased K-m values for phenylethanolamine (10), but only D267A showed a noteworthy (20-fold) decrease in its k(cat) value. Both WT hPNMT and D267A had similar k(cat) values for a rigid analogue, anti-9-amino-6-(trifluoromethyl)benzonorbornene (12), suggesting that Asp267 plays an important role in positioning the substrate but does not participate directly in catalysis. The K-i values for the binding of inhibitors such as 7 to the E219A and D267A variants increased by 2-3 orders of magnitude. Further, the inhibitors were shown to bind up to 50-fold more tightly in the presence of S-adenoSyl-(L)-methionine (3), suggesting that the binding of the latter brings about a conformational change in the enzyme.

Inhibitors of cyclo-oxygenase-2 and secretory phospholipase A2 preserve bone architecture following ovariectomy in adult rats

Epidemiological evidence and in vitro data suggest that COX-2 is a key regulator of accelerated remodeling. Accelerated states of osteoblast and osteoclast activity are regulated by prostaglandins in vitro, but experimental evidence for specific roles of cyclooxygenase-2 (COX-2) and secretory phospholipase A(2) (sPLA(2)) in activated states of remodeling in vivo is lacking. The aim of this study was to determine the effect of specific inhibitors of sPLA(2)-IIa and COX-2 on bone remodeling activated by estrogen deficiency in adult female rats. One hundred and twenty-four adult female Wistar rats were ovariectomized (OVX) or sham-operated. Rats commenced treatment 14 days after surgery with either vehicle, a COX-2 inhibitor (DFU at 0.02 mg/kg/day and 2.0 mg/kg/day) or a sPLA(2)-group-IIa inhibitor (KH064 at 0.4 mg/kg/day and 4.0 mg/kg/day). Treatment continued daily until rats were sacrificed at 70 days or 98 days post-OVX. The right tibiae were harvested, fixed and embedded in methylmethacrylate for structural histomorphometric bone analysis at the proximal tibial metaphysis. The specific COX-2 or sPLA(2) inhibitors prevented ovariectomy-induced (OVX-induced) decreases in trabecular connectivity (P < 0.05); suppressed the acceleration of bone resorption; and maintained bone turnover at SHAM levels following OVX in the rat. The sPLA2 inhibitor significantly suppressed increases in osteoclast surface induced by OVX (P < 0.05), while the effect of COX-2 inhibition was less marked. These findings demonstrate that inhibitors of COX-2 and sPLA(2)-IIa can effectively suppress OVX-induced bone loss in the adult rat by conserving trabecular bone mass and architecture through reduced bone remodeling and decreased resorptive activity. Moreover, we report an important role of sPLA(2)-IIa in osteoclastogenesis that may be independent of the COX-2 metabolic pathway in the OVX rat in vivo. (c) 2006 Elsevier Inc. All rights reserved.

An evaluation of potential mechanism-based inactivation of human drug metabolizing cytochromes P450 by monoamine oxidase inhibitors, including isoniazid

To characterize potential mechanism-based inactivation (MBI) of major human drug-metabolizing cytochromes P450 (CYP) by monoamine oxidase (MAO) inhibitors, including the antitubercular drug isoniazid. Human liver microsomal CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A activities were investigated following co- and preincubation with MAO inhibitors. Inactivation kinetic constants (K-I and k(inact)) were determined where a significant preincubation effect was observed. Spectral studies were conducted to elucidate the mechanisms of inactivation. Hydrazine MAO inhibitors generally exhibited greater inhibition of CYP following preincubation, whereas this was less frequent for the propargylamines, and tranylcypromine and moclobemide. Phenelzine and isoniazid inactivated all CYP but were most potent toward CYP3A and CYP2C19. Respective inactivation kinetic constants (K-I and k(inact)) for isoniazid were 48.6 mu M and 0.042 min(-1) and 79.3 mu M and 0.039 min(-1). Clorgyline was a selective inactivator of CYP1A2 (6.8 mu M and 0.15 min(-1)). Inactivation of CYP was irreversible, consistent with metabolite-intermediate complexation for isoniazid and clorgyline, and haeme destruction for phenelzine. With the exception of phenelzine-mediated CYP3A inactivation, glutathione and superoxide dismutase failed to protect CYP from inactivation by isoniazid and phenelzine. Glutathione partially slowed (17%) the inactivation of CYP1A2 by clorgyline. Alternate substrates or inhibitors generally protected against CYP inactivation. These data are consistent with mechanism-based inactivation of human drug-metabolizing CYP enzymes and suggest that impaired metabolic clearance may contribute to clinical drug-drug interactions with some MAO inhibitors.

A rheology study of high-energy radiolysis of a semicrystalline ethylene-propylene copolymer containing DOP mobilizer

The ractiolysis of a poly(ethylene-co-propylene), Elpro grade P 750 J, marketed by Thai Polypropylene Co. Ltd. for the manufacture of medical goods, was investigated at ambient temperature and melt rheology measured. The roles of calcium stearate, blended with the Elpro as a processing aid, and dioctyl phthalate (DOP), added in various amounts as a radical scavenger, were assessed. Following radiolysis, G' and the viscosity of the polymer melts at 453 K both decreased with increasing radiation dose, even when the mobilizer was present. The results indicated that although the DOP did scavenge radicals, it did not protect the polymer from net chain scission in a low-dose regimen. The value of (G(S) - 4G(X)) was approximately 0.6-0.7. (c) 2006 Wiley Periodicals, Inc.