ORCID Profile
0000-0001-8722-8937
Current Organisation
University of Adelaide
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 24-07-2018
DOI: 10.1002/NBM.3992
Publisher: Elsevier BV
Date: 04-2015
Publisher: Springer Science and Business Media LLC
Date: 04-01-0003
DOI: 10.1007/S10557-016-6664-3
Abstract: Approaches to the pharmacotherapy of angina pectoris have previously centred on the concept that a transient imbalance between myocardial oxygen "demand" and supply within the myocardium can best be addressed by reducing demand (for ex le, with β-adrenoceptor antagonist) or by increasing availability of blood (via coronary vasomotor reactivity adjustment or coronary revascularization). However, this principle is potentially challenged by the emergence of cases of angina unsuitable for such therapies (for ex le because of concomitant severe systolic heart failure) and by the recognition that impaired myocardial energetics may precipitate angina in the absence of fixed or variable coronary obstruction (for ex le in hypertrophic cardiomyopathy). The past 20 years have seen the re-emergence of a class of anti-anginal agents which act primarily by improving efficiency of myocardial oxygen utilization, and thus can correct impaired energetics, simultaneously treating angina and heart failure symptoms. We review the principles underlying the safe use of such agents, beginning with the prototype drug perhexiline maleate, which despite complex pharmacokinetics and potential hepato- or neuro-toxicity has emerged as an attractive management option in many "complicated" cases of angina pectoris.
Publisher: Georg Thieme Verlag KG
Date: 31-08-2014
Abstract: The nitric oxide (NO)/soluble guanylate cyclase (sGC) system is fundamental to endothelial control of vascular tone, but also plays a major role in the negative modulation of platelet aggregation. The phenomenon of platelet NO resistance, or decreased antiaggregatory response to NO, occurs increasingly with advanced age, as well as in the context of cardiovascular disease states such as heart failure, ischemic heart disease, and aortic valve disease. The central causes of NO resistance are "scavenging" of NO and dysfunction of sGC. In the current review, we discuss the roles of several modulators of NO synthesis and of the NO/sGC cascade on changes in platelet physiology with aging, together with potential therapeutic options to reduce associated thrombotic risk.
Publisher: Springer Science and Business Media LLC
Date: 08-2014
DOI: 10.1007/S10557-014-6538-5
Abstract: The thioredoxin system, which consists of thioredoxin (Trx), nicotinamide adenine dinucleotide phosphate (NADPH) and thioredoxin reductase (TrxR), has emerged as a major anti-oxidant involved in the maintenance of cellular physiology and survival. Dysregulation in this system has been associated with metabolic, cardiovascular, and malignant disorders. Thioredoxin-interacting protein (TXNIP), also known as vitamin D-upregulated protein or thioredoxin-binding-protein-2, functions as a physiological inhibitor of Trx, and pathological suppression of Trx by TXNIP has been demonstrated in diabetes and cardiovascular diseases. Furthermore, TXNIP effects are partially Trx-independent these include direct activation of inflammation and inhibition of glucose uptake. Many of the effects of TXNIP are initiated by its dissociation from intra-nuclear binding with Trx or other SH-containing proteins: these effects include its migration to cytoplasm, modulating stress responses in mitochondria and endoplasmic reticulum, and also potentially activating apoptotic pathways. TXNIP also interacts with the nitric oxide (NO) signaling system, with apparent suppression of NO effect. TXNIP production is modulated by redox stress, glucose levels, hypoxia and several inflammatory activators. In recent studies, it has been shown that therapeutic agents including insulin, metformin, angiotensin converting enzyme inhibitors and calcium channel blockers reduce TXNIP expression, although it is uncertain to what extent TXNIP suppression contributes to their clinical efficacy. This review addresses the role of TXNIP in health and in cardiovascular and metabolic disorders. Finally, the potential advantages (and disadvantages) of pharmacological suppression of TXNIP in cardiovascular disease and diabetes are summarized.
Publisher: Oxford University Press (OUP)
Date: 23-11-2018
DOI: 10.1093/EJCTS/EZX388
Publisher: Oxford University Press (OUP)
Date: 04-12-2019
DOI: 10.1093/CVR/CVZ271
Publisher: MDPI AG
Date: 23-09-2022
DOI: 10.3390/BIOMEDICINES10102381
Abstract: Perhexiline (Px) inhibits carnitine palmitoyltransferase 1 (CPT1), which controls uptake of long chain fatty acids into mitochondria. However, occasional cases of hypoglycaemia have been reported in Px-treated patients, raising the possibility that Px may also increase sensitivity to insulin. Furthermore, Px increases anti-aggregatory responses to nitric oxide (NO), an effect which may theoretically parallel insulin sensitization. We therefore sought to examine these relationships in patients with stable Type 2 diabetes (T2D) and cardiovascular disease (n = 30). Px was initiated, and dosage was titrated, to reach the therapeutic range and thus prevent toxicity. Investigations were performed before and after 2 weeks, to examine changes in insulin sensitivity and, utilizing aggregometry in whole blood, platelet responsiveness to the anti-aggregatory effects of the NO donor sodium nitroprusside (SNP). Other parameters that affect may affect NO signalling were also evaluated. Px substantially potentiated inhibition of platelet aggregation by SNP (from 16.7 ± 3.0 to 27.3 ± 3.7% p = 0.005). Px did not change fasting blood glucose concentrations but reduced insulin sensitivity (HOMA-IR score increased from median of 4.47 to 6.08 p = 0.028), and increased fasting plasma insulin concentrations (median 16.5 to 19.0 mU/L p = 0.014). Increases in SNP responses tended (r = −0.30 p = 0.11) to be reciprocally related to increases in HOMA-IR, and increases in HOMA-IR were greater (p = 0.002) in patients without NO-sensitizing effects. No patient developed symptomatic hypoglycaemia, nor was there any other short-term toxicity of Px. Thus, in patients with stable T2D and cardiovascular disease, Px increases anti-aggregatory responsiveness to NO, but is not an insulin sensitizer, and does not induce hypoglycaemia. Absence of NO-sensitizing effect occurs in approximately 30% of Px-treated patients with T2D, and is associated with induction of insulin resistance in these patients.
Publisher: Informa UK Limited
Date: 10-2016
DOI: 10.1080/14728214.2016.1241231
Abstract: Angina pectoris, or symptomatic myocardial ischaemia, reflects an impairment of coronary blood flow, and usually a deficiency of available myocardial energetics. Treatment options vary with the precise cause, which may vary with regards to the roles of increased myocardial oxygen demand versus reduced supply. Traditionally, organic nitrates, β-adrenoceptor antagonists, and non-dihydropyridine calcium antagonists were the only commonly used prophylactic anti-anginal agents. However, many patients failed to respond adequately to such therapy, and/or were unsuitable for their use. Areas covered: A number of 'new' agents have been shown to represent ancillary forms of prophylactic anti-anginal therapy and are particularly useful in patients who are relatively unsuitable for either percutaneous or surgical revascularisation. These include modulators of myocardial metabolic efficiency, such as perhexiline, trimetazidine and ranolazine, as well as high dose allopurinol, nicorandil and ivabradine. The advantages and disadvantages of these various agents are summarized. Expert opinion: 'Optimal' medical treatment of angina pectoris now includes use of agents primarily intended to reduce risk of infarction (e.g. statins, aspirin, ACE inhibitors). In patients whose angina persists despite the use of 'standard' anti-anginal therapy, and who are not ideal for invasive revascularization options, a number of emerging drugs offer prospects of symptomatic relief.
Publisher: Springer Science and Business Media LLC
Date: 08-05-2015
DOI: 10.1007/S00134-015-3822-1
Abstract: To determine whether early goal-directed therapy (EGDT) reduces mortality compared with other resuscitation strategies for patients presenting to the emergency department (ED) with septic shock. Using a search strategy of PubMed, EmBase and CENTRAL, we selected all relevant randomised clinical trials published from January 2000 to January 2015. We translated non-English papers and contacted authors as necessary. Our primary analysis generated a pooled odds ratio (OR) from a fixed-effect model. Sensitivity analyses explored the effect of including non-ED studies, adjusting for study quality, and conducting a random-effects model. Secondary outcomes included organ support and hospital and ICU length of stay. From 2395 initially eligible abstracts, five randomised clinical trials (n = 4735 patients) met all criteria and generally scored high for quality except for lack of blinding. There was no effect on the primary mortality outcome (EGDT: 23.2% [495/2134] versus control: 22.4% [582/2601] pooled OR 1.01 [95% CI 0.88-1.16], P = 0.9, with heterogeneity [I(2) = 57% P = 0.055]). The pooled estimate of 90-day mortality from the three recent multicentre studies (n = 4063) also showed no difference [pooled OR 0.99 (95% CI 0.86-1.15), P = 0.93] with no heterogeneity (I(2) = 0.0% P = 0.97). EGDT increased vasopressor use (OR 1.25 [95% CI 1.10-1.41] P < 0.001) and ICU admission [OR 2.19 (95% CI 1.82-2.65) P < 0.001]. Including six non-ED randomised trials increased heterogeneity (I(2) = 71% P < 0.001) but did not change overall results [pooled OR 0.94 (95% CI 0.82 to 1.07) P = 0.33]. EGDT is not superior to usual care for ED patients with septic shock but is associated with increased utilisation of ICU resources.
Publisher: Wiley
Date: 17-06-2025
DOI: 10.1002/EHF2.12729
Abstract: Takotsubo syndrome (TTS) episodes are primarily initiated by ‘pulse’ release of catecholamines inducing neutrophil infiltration and myocardial inflammation in susceptible in iduals (largely ageing women). Evidence of myocardial inflammation and associated energetic impairment persists for ≥ 3 months post‐acute TTS episodes, suggesting the existence of additional ‘perpetuating’ mechanisms. The effects of B‐type natriuretic peptide (BNP) in suppressing superoxide (O 2 − ) release from neutrophils are transiently impaired in acute heart failure. We also evaluated the extent and duration of BNP‐induced suppression of O 2 − release post‐TTS. TTS patients were studied acutely ( n = 34) and 3 months thereafter ( n = 13) and compared with control subjects ( n = 25). O 2 − generation from neutrophils, triggered by N ‐formyl‐methionyl‐leucyl‐phenylalanine and phorbol myristate acetate, and its suppression by BNP, were measured in vitro . Determinants of variability in BNP effect were sought via univariate and multivariate analyses. Relative to control subjects, in TTS patients, BNP suppression of both phorbol myristate acetate and N ‐formyl‐methionyl‐leucyl‐phenylalanine‐induced O 2 − release was impaired acutely ( P 0.05 for both) this did not improve over the 3‐month recovery period, despite treatment with conventional anti‐failure medication in 85% of patients. No significant correlates of BNP effect (other than TTS) were identified. (1) While TTS is associated with marked and prolonged release of BNP, there is virtually total loss of the ability of BNP to suppress neutrophil O 2 − release and its impact on tissue inflammation. (2) BNP responses do not recover for at least 3 months post‐attacks, suggesting that this might contribute to perpetuation of myocardial inflammation in TTS patients.
Publisher: Springer Science and Business Media LLC
Date: 16-09-2015
DOI: 10.1007/S00228-015-1934-8
Abstract: Perhexiline is a prophylactic anti-ischaemic agent with weak calcium antagonist effect which has been increasingly utilised in the management of refractory angina. The metabolic clearance of perhexiline is modulated by CYP2D6 metaboliser status and stereoselectivity. The current study sought to (1) determine whether the acute accumulation of perhexiline in the myocardium is stereoselective and (2) investigate the relationship between duration of short-term therapy and the potential stereoselective effects of perhexiline within myocardium. Patients (n = 129) from the active arm of a randomised controlled trial of preoperative perhexiline in cardiac surgery were treated with oral perhexiline for a median of 9 days. Correlates of atrial and ventricular concentrations of enantiomers were sought via univariate followed by multivariate analyses. Myocardial uptake of both (+) and (-) perhexiline was greater in ventricles than in atria, and there was more rapid clearance of (-) than (+) perhexiline. The main determinants of atrial uptake of both (+) and (-) perhexiline were the plasma concentrations [(+) perhexiline: β = -0.256, p = 0.015 (-) perhexiline: β = -0.347, p = 0.001] and patients' age [(+) perhexiline: β = 0.300, p = 0.004 (-) perhexiline: β = 0.288, p = 0.005]. Atrial uptake of (+) enantiomer also varied directly with duration of therapy (β = 0.228, p = 0.025), while atrial uptake of (-) perhexiline varied inversely with simultaneous heart rate (β = -0.240, p = 0.015). (1) Uptake of both perhexiline enantiomers into atrium is greater with advanced age and displays evidence of both saturability and minor stereoselectivity. (2) Atrial uptake of (-) perhexiline may selectively modulate heart rate reduction.
Publisher: Elsevier BV
Date: 2021
Publisher: Oxford University Press (OUP)
Date: 26-06-2019
DOI: 10.1093/ICVTS/IVY199
Publisher: Wiley
Date: 12-04-2013
DOI: 10.1002/CLC.22129
Publisher: Informa UK Limited
Date: 02-2012
DOI: 10.1586/ERC.11.190
Abstract: Takotsubo cardiomyopathy (TTC) is a form of reversible acute cardiac dysfunction of uncertain pathogenesis, which occurs predominantly in postmenopausal women, often with antecedent severe stress. Systolic dysfunction most commonly affects the apex of the left ventricle. There is considerable uncertainty regarding the pathogenesis of TTC and the optimal diagnostic methodology. Acute catecholamine release may play a component role, but the regional hypokinesis is associated with an acute inflammatory process, with resultant early release of brain natriuretic peptide (BNP) and N-terminal pro-BNP. As the diagnosis of TTC has largely been a process of exclusion, there has been considerable underdiagnosis. The combination of demographics, preceding history, ECG appearances and N-terminal pro-BNP elevation may provide the basis for improved early diagnosis. Complete recovery takes at least several months, with a risk of recurrent episodes. Efforts to delineate pathogenesis, expedite diagnosis and evaluate residual disability may assist in the development of appropriate treatment regimens.
Publisher: Elsevier BV
Date: 04-2021
DOI: 10.1016/J.JACC.2020.12.065
Abstract: Metabolic perturbations underlie a variety of cardiovascular disease states yet, metabolic interventions to prevent or treat these disorders are sparse. Ketones carry a negative clinical stigma as they are involved in diabetic ketoacidosis. However, evidence from both experimental and clinical research has uncovered a protective role for ketones in cardiovascular disease. Although ketones may provide supplemental fuel for the energy-starved heart, their cardiovascular effects appear to extend far beyond cardiac energetics. Indeed, ketone bodies have been shown to influence a variety of cellular processes including gene transcription, inflammation and oxidative stress, endothelial function, cardiac remodeling, and cardiovascular risk factors. This paper reviews the bioenergetic and pleiotropic effects of ketone bodies that could potentially contribute to its cardiovascular benefits based on evidence from animal and human studies.
Publisher: Wiley
Date: 11-02-2015
DOI: 10.1002/EJHF.242
Abstract: The release of the B-type natriuretic peptide (BNP) is increased in heart failure (HF), a condition associated with oxidative stress. BNP is known to exert anti-inflammatory effects including suppression of neutrophil superoxide (O2(-)) release. However, BNP-based restoration of homeostasis in HF is inadequate, and the equivocal clinical benefit of a recombinant BNP, nesiritide, raises the possibility of attenuated response to BNP. We therefore tested the hypothesis that BNP-induced suppression of neutrophil O2(-) generation is impaired in patients with acute HF. We have recently characterized suppression of neutrophil O2(-) generation (PMA- or fMLP-stimulated neutrophil burst) by BNP as a measure of its physiological activity. In the present study, BNP response was compared in neutrophils of healthy subjects (n = 29) and HF patients (n = 45). Effects of BNP on fMLP-induced phosphorylation of the NAD(P)H oxidase subunit p47phox were also evaluated. In acute HF patients, the suppressing effect of BNP (1 µmol/L) on O2(-) generation was attenuated relative to that in healthy subjects (P < 0.05 for both PMA and fMLP). Analogously, BNP inhibited p47phox phosphorylation in healthy subjects but not in HF patients (P < 0.05). However, O2(-)-suppressing effects of the cell-permeable cGMP analogue (8-pCPT-cGMP) were preserved in acute HF. Conventional HF treatment for 5 weeks partially restored neutrophil BNP responsiveness (n = 25, P < 0.05), despite no significant decrease in plasma NT-proBNP levels. BNP inhibits neutrophil O2(-) generation by suppressing NAD(P)H oxidase assembly. This effect is impaired in acute HF patients, with partial recovery during treatment.
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.AMJMED.2014.11.007
Abstract: Hyperglycemia in patients with acute coronary syndromes is associated with poor outcomes, and its rapid correction with insulin infusion has been shown to restore platelet responsiveness to nitric oxide and to suppress superoxide (O2(-)) generation. Thioredoxin-interacting protein has emerged recently as a pivotal modulator of hyperglycemia-induced inflammation, O2(-) production, and impairment of nitric oxide signaling, but it is not known whether its expression in platelets can be downregulated rapidly. In 12 hyperglycemic patients with acute coronary syndrome, we evaluated the putative role of thioredoxin-interacting protein suppression in the platelet nitric oxide response after reversal of hyperglycemia with insulin infusion. Insulin infusion for 13.0 ± 0.8 (standard error of the mean) hours decreased blood glucose level from 16.6 ± 1.6 mmol/L to 8.7 ± 1.4 mmol/L (P = .002). This induced (1) sensitization of antiaggregatory response to nitric oxide (from 6.5% ± 7.7% to 39.7% ± 7.0%, P < .0001) (2) improved endothelial progenitor cell function (from a median of 45 to 180 colony-forming units, P < .05) and (3) decreases of whole blood reactive oxygen species content (P < .05). However, there was no significant suppression of platelet thioredoxin-interacting protein expression (mean decrease, 59 arbitrary units 95% confidence interval, -193 to +74). Correction of hyperglycemia in patients with acute coronary syndrome rapidly reverses oxidative stress, restoring both platelet nitric oxide responsiveness and endothelial progenitor cell function, but this process is largely or entirely independent of thioredoxin-interacting protein.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2016
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.HLC.2014.06.010
Abstract: Takotsubo cardiomyopathy (TTC) is often associated with hypotension and shock. However, development of hypotension/shock in TTC is not closely related to extent of left ventricular (LV) hypokinesis. We sought to determine whether additional right ventricular (RV) involvement in TTC might contribute to hypotension and shock development and thus to prolonged hospital stay (PHS). We evaluated 102 consecutive TTC patients with acute transthoracic echocardiography (TTE) to detect RV hypokinesis. Correlates of hypotension, shock and PHS were identified by univariate and multivariate analyses. Of the 102 patients evaluated, 33% had RV hypokinesis but only 9% had extensive RV involvement. Within the first 24 hours of admission, severe hypotension (systolic blood pressure (SBP) ≤ 90 mmHg) occurred in 21% of the patients and shock (hypotension + peripheral organ hypo-perfusion) in 16.6% of cases. RV involvement was a univariate but not a multivariate correlate of either hypotension or shock and did not result in PHS. On the other hand, RV involvement predicted more extensive LV hypokinesis and LV systolic dysfunction. In TTC, RV hypokinesis occurs in approximately 33% of cases and correlates with more severe LV wall motion abnormality but not with development of hypotension or shock. These data therefore reinforce previous findings that hypotension/shock in TTC are not purely by impaired cardiac output.
Publisher: Oxford University Press (OUP)
Date: 08-02-2017
DOI: 10.1093/CVR/CVX018
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.HLC.2011.12.004
Abstract: Tako-Tsubo cardiomyopathy (TTC) occurs particularly in post-menopausal women, being precipitated in many cases by severe emotional stress. We describe six patients in whom TTC occurred in association with therapeutic ingestion or overdose of the serotonin/noradrenaline reuptake inhibitor venlafaxine, or its metabolite desvenlafaxine. Importantly, two of the six cases were not post-menopausal women. An increased risk of TTC may account for some of the reported cardiovascular adverse effects of venlafaxine and similar agents.
Publisher: Wiley
Date: 13-10-2018
DOI: 10.1002/EHF2.12211
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2014
End Date: 2015
Funder: National Health and Medical Research Council
View Funded ActivityStart Date: 2019
End Date: 2022
Funder: National Heart Foundation of Australia
View Funded ActivityStart Date: 2019
End Date: 2022
Funder: National Health and Medical Research Council
View Funded Activity