Publications by authors named "Paul J White"

49 Publications

Identifying the core concepts of pharmacology education.

Pharmacol Res Perspect 2021 Aug;9(4):e00836

School of Medical Sciences, Faculty of Medicine and Health Sciences, The University of Sydney, Sydney, NSW, Australia.

Pharmacology education currently lacks an agreed knowledge curriculum. Evidence from physics and biology education indicates that core concepts are useful and effective structures around which such a curriculum can be designed to facilitate student learning. Building on previous work, we developed a novel, criterion-based method to identify the core concepts of pharmacology education. Five novel criteria were developed, based on a literature search, to separate core concepts in pharmacology from topics and facts. Core concepts were agreed to be big ideas, enduring, difficult, applicable across contexts, and useful to solve problems. An exploratory survey of 33 pharmacology educators from Australia and New Zealand produced 109 terms, which were reduced to a working list of 26 concepts during an online workshop. Next, an expert group of 12 educators refined the working list to 19 concepts, by applying the five criteria and consolidating synonyms, and added three additional concepts that emerged during discussions. A confirmatory survey of a larger group resulted in 17 core concepts of pharmacology education. This list may be useful for educators to evaluate existing curricula, design new curricula, and to inform the development of a concept inventory to test attainment of the core concepts in pharmacology.
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http://dx.doi.org/10.1002/prp2.836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8292785PMC
August 2021

Predictors of Pharmacy Student Performance on Written and Clinical Examinations in a Flipped Classroom Curriculum.

Am J Pharm Educ 2020 Dec 19;84(12):8038. Epub 2020 Aug 19.

Monash University, Faculty of Pharmacy and Pharmaceutical Sciences, Parkville, VIC, Australia

To examine the effects of student demographics, prior academic performance, course engagement, and time management on pharmacy students' performance on course examinations and objective structured clinical examinations (OSCEs). Study participants were one cohort of pharmacy students enrolled in a five-year combined Bachelor and Master of Pharmacy degree program at one institution. Variables included student demographics, baseline factors (language assessment and situational judgement test scores), prior academic performance (high school admission rank), course engagement, and student time management of pre-class online activities. Data were collected from course, learning management system, and institutional databases. Data were analyzed for univariate, bivariate, and multivariate associations (four linear regression models) between explanatory factors and outcome variables. Three years of data on 159 pharmacy students were obtained and entered in the dataset. Significant positive predictors of OSCE communication performance included domestic (ie, Australian) student designation, higher baseline written English proficiency, and pre-class online activity completion. Positive predictors of OSCE problem-solving included workshop attendance and low empathy as measured by a baseline situational judgment test (SJT). Positive predictors of performance on year 2 end-of-course examinations included the Australian Tertiary Academic Rank, completing pre-class online activities prior to lectures, and high integrity as measured by an SJT. Several explanatory factors predicted pharmacy students' examination and OSCE performance in the regression models. Future research should continue to study additional contexts, explanatory factors, and outcome variables.
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http://dx.doi.org/10.5688/ajpe8038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7779876PMC
December 2020

Pharmacological Insights Into Safety and Efficacy Determinants for the Development of Adenosine Receptor Biased Agonists in the Treatment of Heart Failure.

Front Pharmacol 2021 11;12:628060. Epub 2021 Mar 11.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.

Adenosine A receptors (AR) are a potential target for cardiac injury treatment due to their cardioprotective/antihypertrophic actions, but drug development has been hampered by on-target side effects such as bradycardia and altered renal hemodynamics. Biased agonism has emerged as an attractive mechanism for AR-mediated cardioprotection that is haemodynamically safe. Here we investigate the pre-clinical pharmacology, efficacy and side-effect profile of the AR agonist neladenoson, shown to be safe but ineffective in phase IIb trials for the treatment of heart failure. We compare this agent with the well-characterized, pan-adenosine receptor (AR) agonist NECA, capadenoson, and the AR biased agonist VCP746, previously shown to be safe and cardioprotective in pre-clinical models of heart failure. We show that like VCP746, neladenoson is biased away from Ca influx relative to NECA and the cAMP pathway at the AR, a profile predictive of a lack of adenosine-like side effects. Additionally, neladenoson was also biased away from the MAPK pathway at the AR. In contrast to VCP746, which displays more 'adenosine-like' signaling at the AR, neladenoson was a highly selective AR agonist, with biased, weak agonism at the AR. Together these results show that unwanted hemodynamic effects of AR agonists can be avoided by compounds biased away from Ca influx relative to cAMP, relative to NECA. The failure of neladenoson to reach primary endpoints in clinical trials suggests that AR-mediated cAMP inhibition may be a poor indicator of effectiveness in chronic heart failure. This study provides additional information that can aid future screening and/or design of improved AR agonists that are safe and efficacious in treating heart failure in patients.
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http://dx.doi.org/10.3389/fphar.2021.628060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7991592PMC
March 2021

Biased agonism at adenosine receptors.

Cell Signal 2021 Jun 19;82:109954. Epub 2021 Feb 19.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia; Department of Pharmacology, Monash University, Melbourne, VIC, Australia. Electronic address:

Adenosine modulates many aspects of human physiology and pathophysiology through binding to the adenosine family of G protein-coupled receptors, which are comprised of four subtypes, the AR, AR, AR and AR. Modulation of adenosine receptor function by exogenous agonists, antagonists and allosteric modulators can be beneficial for a number of conditions including cardiovascular disease, Parkinson's disease, and cancer. Unfortunately, many preclinical drug candidates targeting adenosine receptors have failed in clinical trials due to limited efficacy and/or severe on-target undesired effects. To overcome the key barriers typically encountered when transitioning adenosine receptor ligands into the clinic, research efforts have focussed on exploiting the phenomenon of biased agonism. Biased agonism provides the opportunity to develop ligands that favour therapeutic signalling pathways, whilst avoiding signalling associated with on-target undesired effects. Recent studies have begun to define the structure-function relationships that underpin adenosine receptor biased agonism and establish how this phenomenon can be harnessed therapeutically. In this review we describe the recent advancements made towards achieving therapeutically relevant biased agonism at adenosine receptors.
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http://dx.doi.org/10.1016/j.cellsig.2021.109954DOI Listing
June 2021

The adenosine A G protein-coupled receptor: Recent advances and therapeutic implications.

Pharmacol Ther 2019 06 22;198:20-33. Epub 2019 Jan 22.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia. Electronic address:

The adenosine A receptor (AAR) is one of four adenosine receptor subtypes belonging to the Class A family of G protein-coupled receptors (GPCRs). Until recently, the AAR remained poorly characterised, in part due to its relatively low affinity for the endogenous agonist adenosine and therefore presumed minor physiological significance. However, the substantial increase in extracellular adenosine concentration, the sensitisation of the receptor and the upregulation of AAR expression under conditions of hypoxia and inflammation, suggest the AAR as an exciting therapeutic target in a variety of pathological disease states. Here we discuss the pharmacology of the AAR and outline its role in pathophysiology including ischaemia-reperfusion injury, fibrosis, inflammation and cancer.
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http://dx.doi.org/10.1016/j.pharmthera.2019.01.003DOI Listing
June 2019

Development of a self-report instrument for measuring in-class student engagement reveals that pretending to engage is a significant unrecognized problem.

PLoS One 2018 17;13(10):e0205828. Epub 2018 Oct 17.

Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia.

Student engagement during classes includes behavioural, cognitive and emotional components, and is a pre-requisite for successful active learning environments. A novel approach to measuring student engagement was developed, involving triangulation of real-time student-self report, observation by trained observers and heart rate measurement. The self-report instrument was evaluated in four separate cohorts (n = 123) at Monash University and the University of North Carolina. The six item self-report demonstrated good reliability (Cronbach's alpha values ranged from 0.7-0.81). The self-report showed predictive validity in that small group activities were rated as significantly more engaging than didactic lecturing. Additionally, there was significant inter-instructor variability and within-class variability, indicating good discrimination between classroom activities. This self-report may prove useful to academic teaching staff in evaluating and refining their active learning activities. Independent observation was not found to correlate with student self-report, due in part to students who were pretending to engage being rated as engaged by an observer. Strikingly, students reported that they were pretending to engage for 23% of class time, even for highly regarded instructors. Individual participants were rated as engaged for 42 of the 46 intervals for which they reported that they had "pretended to engage", indicating that the two observers were unable to detect disengagement during periods in which students pretended to engage. Instructors should be aware that student cues such as eye contact and nodding may indicate pretending to engage. One particular self-report item; "I tried a new approach or way of thinking about the content", correlated positively with heart rates, and a controlled study reproduced this finding during two activities that required students to try a new approach to understanding a concept. Agreement with this item also correlated with superior performance on two in-class written assessment tasks (n = 101, p<0.01). Further use of this tool and related educational research may be useful to identify in-class activities that are engaging and likely to lead to improved student attainment of learning outcomes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0205828PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6192645PMC
April 2019

Self-Crosslinking Lipopeptide/DNA/PEGylated Particles: A New Platform for DNA Vaccination Designed for Assembly in Aqueous Solution.

Mol Ther Nucleic Acids 2018 Sep 18;12:504-517. Epub 2018 Jul 18.

Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Melbourne, VIC, Australia. Electronic address:

Delivery of plasmids for gene expression in vivo is an inefficient process that requires improvement and optimization to unlock the clinical potential of DNA vaccines. With ease of manufacture and biocompatibility in mind, we explored condensation of DNA in aqueous solution with a self-crosslinking, endosome-escaping lipopeptide (LP), stearoyl-Cys-His-His-Lys-Lys-Lys-amide (stearoyl-CHK), to produce cationic LP/DNA complexes. To test whether poly(ethylene glycol) (PEG)-ylation of these cationic complexes to neutralize the surface charge would improve the distribution, gene expression, and immune responses poly(ethylene glycol), these LP/DNA complexes were combined with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG). Fluorescence imaging illustrated that the cationic complexes exhibited the highest degree of localization and lowest degree of dispersion throughout the injected muscle, suggesting impaired mobility of cationic particles upon administration. Nanoluciferase reporter assays over a 90-day period demonstrated that gene expression levels in muscle were highest for PEGylated particles, with over a 200-fold higher level of expression than the cationic particles observed at 30 days. Humoral and cell-mediated immune responses were evaluated in vivo after injection of an ovalbumin expression plasmid. PEGylation improved both immune responses to the DNA complexes in mice. Overall, this suggests that PEGylation of cationic lipopeptide complexes can significantly improve both the transgene expression and immunogenicity of intramuscular DNA vaccines.
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http://dx.doi.org/10.1016/j.omtn.2018.05.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6077166PMC
September 2018

Effect of the 5-HT receptor agonist tegaserod on the expression of GRK2 and GRK6 in the rat gastrointestinal tract.

BMC Res Notes 2018 Jun 8;11(1):362. Epub 2018 Jun 8.

Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC, 3052, Australia.

Objective: Tegaserod is a 5-hydroxytryptamine type 4 (5-HT) receptor agonist, formerly used in treating constipation predominant irritable bowel syndrome, which desensitizes 5-HT receptors in rat oesophagus and colon in vitro. Desensitization of 5-HT receptors is regulated by G-protein coupled receptor kinases. This study was designed to assess the effect of 5-HT receptor activation on the expression of GRK2 and GRK6 in the rat oesophagus and distal colon by acute administration of tegaserod.

Results: Rats were treated with a single dose of tegaserod (5 mg/kg) and tissue samples of the oesophagus and distal colon were prepared and level of GRK2 and GRK6 protein expression was determined using western blotting. The immunodensity of GRK2 and GRK6 was normalized against the loading control β-actin and compared with control animals. Acute administration of tegaserod for 1, 2, 3, 4, 6, and 8 h did not change significantly the immunodensity of GRK2 or GRK6 in the oesophagus or GRK2 in the distal colon when compared with control animals. This may indicate that the basal level of GRK2 and GRK6 expression is sufficient to regulate the desensitization of 5-HT receptors in acute drug treatment.
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http://dx.doi.org/10.1186/s13104-018-3495-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5994065PMC
June 2018

New paradigms in adenosine receptor pharmacology: allostery, oligomerization and biased agonism.

Br J Pharmacol 2018 11 21;175(21):4036-4046. Epub 2018 Jun 21.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.

Adenosine receptors are a family of GPCRs containing four subtypes (A , A , A and A receptors), all of which bind the ubiquitous nucleoside adenosine. These receptors play an important role in physiology and pathophysiology and therefore represent attractive drug targets for a range of conditions. The theoretical framework surrounding drug action at adenosine receptors now extends beyond the notion of prototypical agonism and antagonism to encompass more complex pharmacological concepts. New paradigms include allostery, in which ligands bind a topographically distinct receptor site from that of the endogenous agonist, homomeric or heteromeric interactions across receptor oligomers and biased agonism, that is, ligand-dependent differential intracellular signalling. This review provides a concise overview of allostery, oligomerization and biased agonism at adenosine receptors and outlines how these paradigms may enhance future drug discovery endeavours focussed on the development of novel therapeutic agents acting at adenosine receptors.

Linked Articles: This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.
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http://dx.doi.org/10.1111/bph.14337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6177620PMC
November 2018

A Structure-Activity Relationship Study of Bitopic N-Substituted Adenosine Derivatives as Biased Adenosine A Receptor Agonists.

J Med Chem 2018 03 23;61(5):2087-2103. Epub 2018 Feb 23.

Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences , Monash University , Parkville , Victoria 3052 , Australia.

The adenosine A receptor (AAR) is a potential novel therapeutic target for myocardial ischemia-reperfusion injury. However, to date, clinical translation of prototypical AAR agonists has been hindered due to dose limiting adverse effects. Recently, we demonstrated that the biased bitopic agonist 1, consisting of an adenosine pharmacophore linked to an allosteric moiety, could stimulate cardioprotective AAR signaling in the absence of unwanted bradycardia. Therefore, this study aimed to investigate the structure-activity relationship of compound 1 biased agonism. A series of novel derivatives of 1 were synthesized and pharmacologically profiled. Modifications were made to the orthosteric adenosine pharmacophore, linker, and allosteric 2-amino-3-benzoylthiophene pharmacophore to probe the structure-activity relationships, particularly in terms of biased signaling, as well as AAR activity and subtype selectivity. Collectively, our findings demonstrate that the allosteric moiety, particularly the 4-(trifluoromethyl)phenyl substituent of the thiophene scaffold, is important in conferring bitopic ligand bias at the AAR.
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http://dx.doi.org/10.1021/acs.jmedchem.8b00047DOI Listing
March 2018

Student Engagement with a Flipped Classroom Teaching Design Affects Pharmacology Examination Performance in a Manner Dependent on Question Type.

Am J Pharm Educ 2017 Nov;81(9):5931

Monash University, Parkville, Victoria, Australia.

To investigate the relationship between student engagement with the key elements of a flipped classroom approach (preparation and attendance), their attitudes to learning, including strategy development, and their performance on two types of examination questions (knowledge recall and providing rational predictions when faced with novel scenarios). This study correlated student engagement with the flipped classroom and student disposition to learning with student ability to solve novel scenarios in examinations. Students who both prepared for and attended classes performed significantly better on examination questions that required analysis of novel scenarios compared to students who did not prepare and missed classes. However, there was no difference for both groups of students on examination questions that required knowledge and comprehension. Student motivation and use of strategies correlated with higher examination scores on questions requiring novel scenario analysis. There is a synergistic relationship between class preparation and attendance. The combination of preparation and attendance was positively correlated to assessment type; the relationship was apparent for questions requiring students to solve novel problems but not for questions requiring knowledge or comprehension.
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http://dx.doi.org/10.5688/ajpe5931DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5738940PMC
November 2017

α-Adrenoceptors activate mTOR signalling and glucose uptake in cardiomyocytes.

Biochem Pharmacol 2018 02 24;148:27-40. Epub 2017 Nov 24.

Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden. Electronic address:

The capacity of G protein-coupled receptors to modulate mechanistic target of rapamycin (mTOR) activity is a newly emerging paradigm with the potential to link cell surface receptors with cell survival. Cardiomyocyte viability is linked to signalling pathways involving Akt and mTOR, as well as increased glucose uptake and utilization. Our aim was to determine whether the α-adrenoceptor (AR) couples to these protective pathways, and increased glucose uptake. We characterised α-AR signalling in CHO-K1 cells co-expressing the human α-AR and GLUT4 (CHOαGLUT4myc) and in neonatal rat ventricular cardiomyocytes (NRVM), and measured glucose uptake, intracellular Ca mobilization, and phosphorylation of mTOR, Akt, 5' adenosine monophosphate-activated kinase (AMPK) and S6 ribosomal protein (S6rp). In both systems, noradrenaline and the α-AR selective agonist A61603 stimulated glucose uptake by parallel pathways involving mTOR and AMPK, whereas another α-AR agonist oxymetazoline increased glucose uptake predominantly by mTOR. All agonists promoted phosphorylation of mTOR at Ser2448 and Ser2481, indicating activation of both mTORC1 and mTORC2, but did not increase Akt phosphorylation. In CHOαGLUT4myc cells, siRNA directed against rictor but not raptor suppressed α-AR mediated glucose uptake. We have thus identified mTORC2 as a key component in glucose uptake stimulated by α-AR agonists. Our findings identify a novel link between the α-AR, mTORC2 and glucose uptake, that have been implicated separately in cardiomyocyte survival. Our studies provide an improved framework for examining the utility of α-AR selective agonists as tools in the treatment of cardiac dysfunction.
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http://dx.doi.org/10.1016/j.bcp.2017.11.016DOI Listing
February 2018

Virtual reality body motion induced navigational controllers and their effects on simulator sickness and pathfinding.

Annu Int Conf IEEE Eng Med Biol Soc 2017 Jul;2017:4175-4178

Virtual reality (VR) navigation is usually constrained by plausible simulator sickness (SS) and intuitive user interaction. The paper reports on the use of four different degrees of body motion induced navigational VR controllers, a TiltChair, omni-directional treadmill, a manual wheelchair joystick (VRNChair), and a joystick in relation to a participant's SS occurrence and a controller's intuitive utilization. Twenty young adult participants utilized all controllers to navigate through the same VR task environment in separate sessions. Throughout the sessions, SS occurrence was measured from a severity score by a standard SS questionnaire and from body sway by a center of pressure path length with eyes opened and closed. SS occurrence did not significantly differ among the controllers. However, time spent in VR significantly contributed to SS occurrence; hence, a few breaks to minimize SS should be interjected throughout a VR task. For all task trials, we recorded the participant's travel trajectories to investigate each controller's intuitive utilization from a computed traversed distance. Shorter traversed distances indicated that participants intuitively utilized the TiltChair with a slower speed; while longer traversed distances indicated participants struggled to utilize the omni-directional treadmill with a unnaturalistic stimulation of gait. Therefore, VR navigation should use technologies best suited for the intended age group that minimizes SS, and produces intuitive interactions for the participants.
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http://dx.doi.org/10.1109/EMBC.2017.8037776DOI Listing
July 2017

Virtual reality body motion induced navigational controllers and their effects on simulator sickness and pathfinding.

Annu Int Conf IEEE Eng Med Biol Soc 2017 Jul;2017:4175-4178

Virtual reality (VR) navigation is usually constrained by plausible simulator sickness (SS) and intuitive user interaction. The paper reports on the use of four different degrees of body motion induced navigational VR controllers, a TiltChair, omni-directional treadmill, a manual wheelchair joystick (VRNChair), and a joystick in relation to a participant's SS occurrence and a controller's intuitive utilization. Twenty young adult participants utilized all controllers to navigate through the same VR task environment in separate sessions. Throughout the sessions, SS occurrence was measured from a severity score by a standard SS questionnaire and from body sway by a center of pressure path length with eyes opened and closed. SS occurrence did not significantly differ among the controllers. However, time spent in VR significantly contributed to SS occurrence; hence, a few breaks to minimize SS should be interjected throughout a VR task. For all task trials, we recorded the participant's travel trajectories to investigate each controller's intuitive utilization from a computed traversed distance. Shorter traversed distances indicated that participants intuitively utilized the TiltChair with a slower speed; while longer traversed distances indicated participants struggled to utilize the omni-directional treadmill with a unnaturalistic stimulation of gait. Therefore, VR navigation should use technologies best suited for the intended age group that minimizes SS, and produces intuitive interactions for the participants.
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http://dx.doi.org/10.1109/EMBC.2017.8037776DOI Listing
July 2017

Targeting Adenosine Receptors for the Treatment of Cardiac Fibrosis.

Front Pharmacol 2017 5;8:243. Epub 2017 May 5.

Monash Institute of Pharmaceutical Sciences, Monash University, ParkvilleVIC, Australia.

Adenosine is a ubiquitous molecule with key regulatory and cytoprotective mechanisms at times of metabolic imbalance in the body. Among a plethora of physiological actions, adenosine has an important role in attenuating ischaemia-reperfusion injury and modulating the ensuing fibrosis and tissue remodeling following myocardial damage. Adenosine exerts these actions through interaction with four adenosine G protein-coupled receptors expressed in the heart. The adenosine A receptor (AAR) is the most abundant adenosine receptor (AR) in cardiac fibroblasts and is largely responsible for the influence of adenosine on cardiac fibrosis. and studies demonstrate that acute AAR stimulation can decrease fibrosis through the inhibition of fibroblast proliferation and reduction in collagen synthesis. However, in contrast, there is also evidence that chronic AAR antagonism reduces tissue fibrosis. This review explores the opposing pro- and anti-fibrotic activity attributed to the activation of cardiac ARs and investigates the therapeutic potential of targeting ARs for the treatment of cardiac fibrosis.
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http://dx.doi.org/10.3389/fphar.2017.00243DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5418340PMC
May 2017

Capadenoson, a clinically trialed partial adenosine A receptor agonist, can stimulate adenosine A receptor biased agonism.

Biochem Pharmacol 2017 07 23;135:79-89. Epub 2017 Mar 23.

Drug Discovery Biology & Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia. Electronic address:

The adenosine A receptor (AAR) has been identified as an important therapeutic target in cardiovascular disease, however in vitro and in vivo targeting has been limited by the paucity of pharmacological tools, particularly potent agonists. Interestingly, 2-((6-amino-3,5-dicyano-4-(4-(cyclopropylmethoxy)phenyl)-2-pyridinyl)thio)acetamide (BAY60-6583), a potent and subtype-selective AAR agonist, has the same core structure as 2-amino-6-[[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methylsulfanyl]-4-[4-(2-hydroxyethoxy)phenyl]pyridine-3,5-dicarbonitril (capadenoson). Capadenoson, currently classified as an adenosine A receptor (AAR) partial agonist, has undergone two Phase IIa clinical trials, initially in patients with atrial fibrillation and subsequently in patients with stable angina. Capadenoson has also been shown to decrease cardiac remodeling in an animal model of advanced heart failure and a capadenoson derivative, neladenoson bialanate, recently entered clinical development for the treatment of chronic heart failure. The therapeutic effects of capadenoson are currently thought to be mediated through the AAR. However, the ability of capadenoson to stimulate additional adenosine receptor subtypes, in particular the AAR, has not been rigorously assessed. In this study, we demonstrate that capadenoson does indeed have significant AAR activity in physiologically relevant cells, cardiac fibroblasts and cardiomyocytes, which endogenously express the AAR. Relative to the non-selective adenosine receptor agonist NECA, capadenoson was a biased AAR agonist with a preference for cAMP signal transduction over other downstream mediators in cells with recombinant and endogenous AAR expression. These findings suggest the reclassification of capadenoson as a dual AAR/AAR agonist. Furthermore, a potential AAR contribution should be an important consideration for the future clinical development of capadenoson-like therapeutics, as the AAR can promote cardioprotection and modulate cardiac fibrosis in heart disease.
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http://dx.doi.org/10.1016/j.bcp.2017.03.014DOI Listing
July 2017

Developing a Framework for Objective Structured Clinical Examinations Using the Nominal Group Technique.

Am J Pharm Educ 2016 Nov;80(9):158

Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia.

To use the nominal group technique to develop a framework to improve existing and develop new objective structured clinical examinations (OSCEs) within a four-year bachelor of pharmacy course. Using the nominal group technique, a unique method of group interview that combines qualitative and quantitative data collection, focus groups were conducted with faculty members, practicing pharmacists, and undergraduate pharmacy students. Five draft OSCEs frameworks were suggested and participants were asked to generate new framework ideas. Two focus groups (n=9 and n=7) generated nine extra frameworks. Two of these frameworks, one from each focus group, ranked highest (mean scores of 4.4 and 4.1 on a 5-point scale) and were similar in nature. The project team used these two frameworks to produce the final framework, which includes an OSCE in every year of the course, earlier implementation of teaching OSCEs, and the use of independent simulated patients who are not examiners. The new OSCE framework provides a consistent structure from course entry to exit and ensures graduates meet internship requirements.
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http://dx.doi.org/10.5688/ajpe809158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5221840PMC
November 2016

Novel Irreversible Agonists Acting at the A Adenosine Receptor.

J Med Chem 2016 12 13;59(24):11182-11194. Epub 2016 Dec 13.

Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia.

The A adenosine receptor (AAR) is an important G protein-coupled receptor that regulates a range of physiological functions. Herein we report the discovery of novel irreversible agonists acting at the AAR, which have the potential to serve as useful research tools for studying receptor structure and function. A series of novel adenosine derivatives bearing electrophilic substituents was synthesized, and four compounds, 8b, 15a, 15b, and 15d, were shown to possess similar potency and efficacy to the reference high efficacy agonist, NECA, in an assay of ERK1/2 phosphorylation assay. Insensitivity to antagonist addition in a real-time, label-free, xCELLigence assay was subsequently used to identify compounds that likely mediated their agonism through an irreversible interaction with the AAR. Of these compounds, 15b and 15d were more directly validated as irreversible agonists of the AAR using membrane-based [H]DPCPX and [S]GTPγS binding experiments.
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http://dx.doi.org/10.1021/acs.jmedchem.6b01561DOI Listing
December 2016

Neurocognitive Treatment for a Patient with Alzheimer's Disease Using a Virtual Reality Navigational Environment.

J Exp Neurosci 2016 8;10:129-135. Epub 2016 Nov 8.

Department of Biomedical Engineering, University of Manitoba, Winnipeg, Manitoba, Canada.

In this case study, a man at the onset of Alzheimer's disease (AD) was enrolled in a cognitive treatment program based upon spatial navigation in a virtual reality (VR) environment. We trained him to navigate to targets in a symmetric, landmark-less virtual building. Our research goals were to determine whether an individual with AD could learn to navigate in a simple VR navigation (VRN) environment and whether that training could also bring real-life cognitive benefits. The results show that our participant learned to perfectly navigate to desired targets in the VRN environment over the course of the training program. Furthermore, subjective feedback from his primary caregiver (his wife) indicated that his skill at navigating while driving improved noticeably and that he enjoyed cognitive improvement in his daily life at home. These results suggest that VRN treatments might benefit other people with AD.
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http://dx.doi.org/10.4137/JEN.S40827DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102253PMC
November 2016

Extracellular Loop 2 of the Adenosine A1 Receptor Has a Key Role in Orthosteric Ligand Affinity and Agonist Efficacy.

Mol Pharmacol 2016 Dec 28;90(6):703-714. Epub 2016 Sep 28.

Monash Institute of Pharmaceutical Sciences (A.T.N.N., J.-A.B., T.T., L.L.M, K.J.G, P.J.W, P.M.S, A.C., L.T.M), Monash e-Research Centre (T.D.N), and Department of Pharmacology (A.T.N.N, J.-A.B., K.J.G., P.M.S., A.C., L.T.M), Monash University, Parkville, Victoria, Australia

The adenosine A G protein-coupled receptor (AAR) is an important therapeutic target implicated in a wide range of cardiovascular and neuronal disorders. Although it is well established that the AAR orthosteric site is located within the receptor's transmembrane (TM) bundle, prior studies have implicated extracellular loop 2 (ECL2) as having a significant role in contributing to orthosteric ligand affinity and signaling for various G protein-coupled receptors (GPCRs). We thus performed extensive alanine scanning mutagenesis of AAR-ECL2 to explore the role of this domain on AAR orthosteric ligand pharmacology. Using quantitative analytical approaches and molecular modeling, we identified ECL2 residues that interact either directly or indirectly with orthosteric agonists and antagonists. Discrete mutations proximal to a conserved ECL2-TM3 disulfide bond selectively affected orthosteric ligand affinity, whereas a cluster of five residues near the TM4-ECL2 juncture influenced orthosteric agonist efficacy. A combination of ligand docking, molecular dynamics simulations, and mutagenesis results suggested that the orthosteric agonist 5'-N-ethylcarboxamidoadenosine binds transiently to an extracellular vestibule formed by ECL2 and the top of TM5 and TM7, prior to entry into the canonical TM bundle orthosteric site. Collectively, this study highlights a key role for ECL2 in AAR orthosteric ligand binding and receptor activation.
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http://dx.doi.org/10.1124/mol.116.105007DOI Listing
December 2016

Role of the Second Extracellular Loop of the Adenosine A1 Receptor on Allosteric Modulator Binding, Signaling, and Cooperativity.

Mol Pharmacol 2016 Dec 28;90(6):715-725. Epub 2016 Sep 28.

Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia

Allosteric modulation of adenosine A1 receptors (A1ARs) offers a novel therapeutic approach for the treatment of numerous central and peripheral disorders; however, despite decades of research, there is a relative paucity of structural information regarding the A1AR allosteric site and mechanisms governing cooperativity with orthosteric ligands. We combined alanine-scanning mutagenesis of the A1AR second extracellular loop (ECL2) with radioligand binding and functional interaction assays to quantify effects on allosteric ligand affinity, cooperativity, and efficacy. Docking and molecular dynamics (MD) simulations were performed using an A1AR homology model based on an agonist-bound A2AAR structure. Substitution of E172ECL2 for alanine reduced the affinity of the allosteric modulators PD81723 and VCP171 for the unoccupied A1AR. Residues involved in cooperativity with the orthosteric agonist NECA were different in PD81723 and VCP171; positive cooperativity between PD81723 and NECA was reduced on alanine substitution of a number of ECL2 residues, including E170ECL2 and K173ECL2, whereas mutation of W146ECL2 and W156ECL2 decreased VCP171 cooperativity with NECA. Molecular modeling localized a likely allosteric pocket for both modulators to an extracellular vestibule that overlaps with a region used by orthosteric ligands as they transit into the canonical A1AR orthosteric site. MD simulations confirmed a key interaction between E172ECL2 and both modulators. Bound PD81723 is flanked by another residue, E170ECL2, which forms hydrogen bonds with adjacent K168ECL2 and K173ECL2. Collectively, our data suggest E172ECL2 is a key allosteric ligand-binding determinant, whereas hydrogen-bonding networks within the extracellular vestibule may facilitate the transmission of cooperativity between orthosteric and allosteric sites.
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http://dx.doi.org/10.1124/mol.116.105015DOI Listing
December 2016

Tissue-specific Calibration of Real-time PCR Facilitates Absolute Quantification of Plasmid DNA in Biodistribution Studies.

Mol Ther Nucleic Acids 2016 Oct 4;5(10):e371. Epub 2016 Oct 4.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Melbourne, Australia.

Analysis of the tissue distribution of plasmid DNA after administration of nonviral gene delivery systems is best accomplished using quantitative real-time polymerase chain reaction (qPCR), although published strategies do not allow determination of the absolute mass of plasmid delivered to different tissues. Generally, data is expressed as the mass of plasmid relative to the mass of genomic DNA (gDNA) in the sample. This strategy is adequate for comparisons of efficiency of delivery to a single site but it does not allow direct comparison of delivery to multiple tissues, as the mass of gDNA extracted per unit mass of each tissue is different. We show here that by constructing qPCR standard curves for each tissue it is possible to determine the dose of intact plasmid remaining in each tissue, which is a more useful parameter when comparing the fates of different formulations of DNA. We exemplify the use of this tissue-specific qPCR method by comparing the delivery of naked DNA, cationic DNA complexes, and neutral PEGylated DNA complexes after intramuscular injection. Generally, larger masses of intact plasmid were present 24 hours after injection of DNA complexes, and neutral complexes resulted in delivery of a larger mass of intact plasmid to the spleen.
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http://dx.doi.org/10.1038/mtna.2016.79DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5095683PMC
October 2016

The hybrid molecule, VCP746, is a potent adenosine A2B receptor agonist that stimulates anti-fibrotic signalling.

Biochem Pharmacol 2016 Oct 9;117:46-56. Epub 2016 Aug 9.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology, Monash University, Parkville, VIC 3052, Australia. Electronic address:

We have recently described the rationally-designed adenosine receptor agonist, 4-(5-amino-4-benzoyl-3-(3-(trifluoromethyl)phenyl)thiophen-2-yl)-N-(6-(9-((2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxylmethyl)tetrahydro-furan-2-yl)-9H-purin-6-ylamino)hexyl)benzamide (VCP746), a hybrid molecule consisting of an adenosine moiety linked to an adenosine A1 receptor (A1AR) allosteric modulator moiety. At the A1AR, VCP746 mediated cardioprotection in the absence of haemodynamic side effects such as bradycardia. The current study has now identified VCP746 as an important pharmacological tool for the adenosine A2B receptor (A2BAR). The binding and function of VCP746 at the A2BAR was rigorously characterised in a heterologous expression system, in addition to examination of its anti-fibrotic signalling in cardiac- and renal-derived cells. In FlpInCHO cells stably expressing the human A2BAR, VCP746 was a high affinity, high potency A2BAR agonist that stimulated Gs- and Gq-mediated signal transduction, with an apparent lack of system bias relative to prototypical A2BAR agonists. The distinct agonist profile may result from an atypical binding mode of VCP746 at the A2BAR, which was consistent with a bivalent mechanism of receptor interaction. In isolated neonatal rat cardiac fibroblasts (NCF), VCP746 stimulated potent inhibition of both TGF-β1- and angiotensin II-mediated collagen synthesis. Similar attenuation of TGF-β1-mediated collagen synthesis was observed in renal mesangial cells (RMC). The anti-fibrotic signalling mediated by VCP746 in NCF and RMC was selectively reversed in the presence of an A2BAR antagonist. Thus, we believe, VCP746 represents an important tool to further investigate the role of the A2BAR in cardiac (patho)physiology.
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http://dx.doi.org/10.1016/j.bcp.2016.08.007DOI Listing
October 2016

VCP746, a novel A1 adenosine receptor biased agonist, reduces hypertrophy in a rat neonatal cardiac myocyte model.

Clin Exp Pharmacol Physiol 2016 10;43(10):976-82

Centre of Cardiovascular Research and Education in Therapeutics, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Vic., Australia.

VCP746 is a novel A1 adenosine receptor (A1 AR) biased agonist previously shown to be cytoprotective with no effect on heart rate. The aim of this study was to investigate the potential anti-hypertrophic effect of VCP746 in neonatal rat cardiac myocytes (NCM). NCM hypertrophy was stimulated with interleukin (IL)-1β (10 ng/mL), tumour necrosis factor (TNF)-α (10 ng/mL) or Ang II (100 nmol/L) and was assessed by (3) H-leucine incorporation assay. VCP746 significantly inhibited IL-1β-, TNF-α- and Ang II-stimulated NCM hypertrophy as determined by (3) H-leucine incorporation. The anti-hypertrophic effect of VCP746 was also more potent than that of the prototypical A1 AR agonist, N(6) -cyclopentyladenosine (CPA). Further investigation with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay showed that neither CPA nor VCP746 had any effect on cell viability, confirming that the reduction in (3) H-leucine incorporation mediated by CPA and VCP746 was not due to a reduction in cell viability. IL-1β, TNF-α and Ang II were also shown to increase the mRNA expression of hypertrophy biomarkers, ANP, β-MHC and α-SKA in NCM. Treatment with VCP746 at concentrations as low as 1 nmol/L suppressed mRNA expression of ANP, β-MHC and α-SKA stimulated by IL-1β, TNF-α or Ang II, demonstrating the broad mechanistic basis of the potent anti-hypertrophic effect of VCP746. This study has shown that the novel A1 AR agonist, VCP746, is able to attenuate cardiac myocyte hypertrophy. As such, VCP746 is potentially useful as a pharmacological agent in attenuating cardiac remodelling, especially in the post-myocardial infarction setting, given its previously established cytoprotective properties.
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http://dx.doi.org/10.1111/1440-1681.12616DOI Listing
October 2016

Ligand-Independent Adenosine A2B Receptor Constitutive Activity as a Promoter of Prostate Cancer Cell Proliferation.

J Pharmacol Exp Ther 2016 Apr 20;357(1):36-44. Epub 2016 Jan 20.

Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia

Aberrant ligand-independent G protein-coupled receptor constitutive activity has been implicated in the pathophysiology of a number of cancers. The adenosine A2B receptor (A2BAR) is dynamically upregulated under pathologic conditions associated with a hypoxic microenvironment, including solid tumors. This, in turn, may amplify ligand-independent A2BAR signal transduction. The contribution of A2BAR constitutive activity to disease progression is currently unknown yet of fundamental importance, as the preferred therapeutic modality for drugs designed to reduce A2BAR constitutive activity would be inverse agonism as opposed to neutral antagonism. The current study investigated A2BAR constitutive activity in a heterologous expression system and a native 22Rv1 human prostate cancer cell line exposed to hypoxic conditions (2% O2). The A2BAR inverse agonists, ZM241385 [4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol] or PSB-603 (8-(4-(4-(4-chlorophenyl)piperazide-1-sulfonyl)phenyl)-1-propylxanthine), mediated a concentration-dependent decrease in baseline cAMP levels in both cellular systems. Proliferation of multiple prostate cancer cell lines was also attenuated in the presence of PSB-603. Importantly, both the decrease in baseline cAMP accumulation and the reduction of proliferation were not influenced by the addition of adenosine deaminase, demonstrating that these effects are not dependent on stimulation of A2BARs by the endogenous agonist adenosine. Our study is the first to reveal that wild-type human A2BARs have high constitutive activity in both model and native cells. Furthermore, our findings demonstrate that this ligand-independent A2BAR constitutive activity is sufficient to promote prostate cancer cell proliferation in vitro. More broadly, A2BAR constitutive activity may have wider, currently unappreciated implications in pathologic conditions associated with a hypoxic microenvironment.
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http://dx.doi.org/10.1124/jpet.115.230003DOI Listing
April 2016

Effect of viewing mode on pathfinding in immersive Virtual Reality.

Annu Int Conf IEEE Eng Med Biol Soc 2015 Aug;2015:4619-22

The use of Head Mounted Displays (HMDs) to view Virtual Reality Environments (VREs) has received much attention recently. This paper reports on the difference between actual humans' navigation in a VRE viewed through an HMD compared to that in the same VRE viewed on a laptop PC display. A novel Virtual Reality (VR) Navigation input device (VRNChair), designed by our team, was paired with an Oculus Rift DK2 Head-Mounted Display (HMD). People used the VRNChair to navigate a VRE, and we analyzed their navigational trajectories with and without the HMD to investigate plausible differences in performance due to the display device. It was found that people's navigational trajectories were more accurate while wearing the HMD compared to viewing an LCD monitor; however, the duration to complete a navigation task remained the same. This implies that increased immersion in VR results in an improvement in pathfinding. In addition, motion sickness caused by using an HMD can be reduced if one uses an input device such as our VRNChair. The VRNChair paired with an HMD provides vestibular stimulation as one moves in the VRE, because movements in the VRE are synchronized with movements in the real environment.
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http://dx.doi.org/10.1109/EMBC.2015.7319423DOI Listing
August 2015

Quantification of adenosine A(1) receptor biased agonism: Implications for drug discovery.

Biochem Pharmacol 2016 Jan 12;99:101-12. Epub 2015 Nov 12.

Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia. Electronic address:

Adenosine A1 receptor (A1AR) stimulation is a powerful protective mechanism in cerebral and cardiac ischemia-reperfusion injury. Despite this, therapeutic targeting of the A1AR for the treatment of ischemia-reperfusion injury has been largely unsuccessful, as high concentrations of prototypical A1AR agonists impart significant hemodynamic effects, particularly pronounced bradycardia, atrioventricular block and hypotension. Exploiting the phenomenon of biased agonism to develop ligands that promote A1AR cytoprotection in the absence of adverse hemodynamic effects remains a relatively unexplored, but exciting, approach to overcome current limitations. In native systems, the atypical A1AR agonists VCP746 and capadenoson retain cytoprotective signaling in the absence of bradycardia, a phenomenon suggestive of biased agonism. The current study used pharmacological inhibitors to investigate A1AR mediated cytoprotective signal transduction in a CHO FlpIn cell background, thus identifying candidate pathways for quantitative bias profiling, including cAMP, extracellular signal-regulated kinases 1 and 2 and Akt1/2/3. Subsequently, effects on cell survival and the bias profile of VCP746 and capadenoson were determined and compared to that of the prototypical A1AR agonists, NECA, R-PIA, MeCCPA and CPA. We found that prototypical agonists do not display significant bias for any of the pathways assessed. In contrast, VCP746 and capadenoson show significant bias away from calcium mobilization relative to all pathways tested. These studies demonstrate that quantitative "fingerprinting" of biased agonism within a model system can enable ligands to be clustered by their bias profile, which in turn may be predictive of preferential physiologically relevant in vivo pharmacology.
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http://dx.doi.org/10.1016/j.bcp.2015.11.013DOI Listing
January 2016

Buccal mucosal delivery of a potent peptide leads to therapeutically-relevant plasma concentrations for the treatment of autoimmune diseases.

J Control Release 2015 Feb 4;199:37-44. Epub 2014 Dec 4.

Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia. Electronic address:

Stichodactyla helianthus neurotoxin (ShK) is an immunomodulatory peptide currently under development for the treatment of autoimmune diseases, including multiple sclerosis and rheumatoid arthritis by parenteral administration. To overcome the low patient compliance of conventional self-injections, we have investigated the potential of the buccal mucosa as an alternative delivery route for ShK both in vitro and in vivo. After application of fluorescent 5-Fam-ShK to untreated porcine buccal mucosa, there was no detectable peptide in the receptor chamber using an in vitro Ussing chamber model. However, the addition of the surfactants sodium taurodeoxycholate hydrate or cetrimide, and formulation of ShK in a chitosan mucoadhesive gel, led to 0.05-0.13% and 1.1% of the applied dose, respectively, appearing in the receptor chamber over 5h. Moreover, confocal microscopic studies demonstrated significantly enhanced buccal mucosal retention of the peptide (measured by mucosal fluorescence associated with 5-Fam-ShK) when enhancement strategies were employed. Administration of 5-Fam-ShK to mice (10mg/kg in a mucoadhesive chitosan-based gel (3%, w/v) with or without cetrimide (5%, w/w)) resulted in average plasma concentrations of 2.6-16.2nM between 2 and 6h, which were substantially higher than the pM concentrations required for therapeutic activity. This study demonstrated that the buccal mucosa is a promising administration route for the systemic delivery of ShK for the treatment of autoimmune diseases.
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http://dx.doi.org/10.1016/j.jconrel.2014.12.001DOI Listing
February 2015

Separation of on-target efficacy from adverse effects through rational design of a bitopic adenosine receptor agonist.

Proc Natl Acad Sci U S A 2014 Mar 11;111(12):4614-9. Epub 2014 Mar 11.

Drug Discovery Biology and Department of Pharmacology and Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia.

The concepts of allosteric modulation and biased agonism are revolutionizing modern approaches to drug discovery, particularly in the field of G protein-coupled receptors (GPCRs). Both phenomena exploit topographically distinct binding sites to promote unique GPCR conformations that can lead to different patterns of cellular responsiveness. The adenosine A1 GPCR (A1AR) is a major therapeutic target for cardioprotection, but current agents acting on the receptor are clinically limited for this indication because of on-target bradycardia as a serious adverse effect. In the current study, we have rationally designed a novel A1AR ligand (VCP746)--a hybrid molecule comprising adenosine linked to a positive allosteric modulator--specifically to engender biased signaling at the A1AR. We validate that the interaction of VCP746 with the A1AR is consistent with a bitopic mode of receptor engagement (i.e., concomitant association with orthosteric and allosteric sites) and that the compound displays biased agonism relative to prototypical A1AR ligands. Importantly, we also show that the unique pharmacology of VCP746 is (patho)physiologically relevant, because the compound protects against ischemic insult in native A1AR-expressing cardiomyoblasts and cardiomyocytes but does not affect rat atrial heart rate. Thus, this study provides proof of concept that bitopic ligands can be designed as biased agonists to promote on-target efficacy without on-target side effects.
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http://dx.doi.org/10.1073/pnas.1320962111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970544PMC
March 2014

HCN channelopathy and cardiac electrophysiologic dysfunction in genetic and acquired rat epilepsy models.

Epilepsia 2014 Apr 4;55(4):609-20. Epub 2014 Mar 4.

Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.

Objective: Evidence from animal and human studies indicates that epilepsy can affect cardiac function, although the molecular basis of this remains poorly understood. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels generate pacemaker activity and modulate cellular excitability in the brain and heart, with altered expression and function associated with epilepsy and cardiomyopathies. Whether HCN expression is altered in the heart in association with epilepsy has not been investigated previously. We studied cardiac electrophysiologic properties and HCN channel subunit expression in rat models of genetic generalized epilepsy (Genetic Absence Epilepsy Rats from Strasbourg, GAERS) and acquired temporal lobe epilepsy (post-status epilepticus SE). We hypothesized that the development of epilepsy is associated with altered cardiac electrophysiologic function and altered cardiac HCN channel expression.

Methods: Electrocardiography studies were recorded in vivo in rats and in vitro in isolated hearts. Cardiac HCN channel messenger RNA (mRNA) and protein expression were measured using quantitative PCR and Western blotting respectively.

Results: Cardiac electrophysiology was significantly altered in adult GAERS, with slower heart rate, shorter QRS duration, longer QTc interval, and greater standard deviation of RR intervals compared to control rats. In the post-SE model, we observed similar interictal changes in several of these parameters, and we also observed consistent and striking bradycardia associated with the onset of ictal activity. Molecular analysis demonstrated significant reductions in cardiac HCN2 mRNA and protein expression in both models, providing a molecular correlate of these electrophysiologic abnormalities.

Significance: These results demonstrate that ion channelopathies and cardiac dysfunction can develop as a secondary consequence of chronic epilepsy, which may have relevance for the pathophysiology of cardiac dysfunction in patients with epilepsy.
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http://dx.doi.org/10.1111/epi.12563DOI Listing
April 2014
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