Vascular Biology & Cardiovascular Medicine
Professor Ben Freedman
In general there are a large variety of projects in cardiovascular medicine that can be offered to students both at the ANZAC Research Institute as well as Concord Hospital (one of the major teaching hospitals in the Sydney region). These studies range from basic cellular and molecular science through human physiology and pathophysiology.
Examples of research include work basic research on atherosclerosis, the cause and treatment of acute heart attack, the physiology and pathophysiology of coronary disease, the cause and prevention of sudden cardiac death, electrophysiology of the heart, epidemiology of cardiovascular disease and planning and performance of large international clinical trials in cardiovascular medicine.
Contact: Professor Ben Freedman
Tel: 9515 6519
Email:
Vascular Biology Laboratory
Dr Paul Witting, Professor Ben Freedman, Associate Professor Len Kritharides, Associate Professor David Brieger and Dr Harry Lowe
Project 1: Can synthetic antioxidants prevent the oxidation and modification of cardiac lipids, vitamins and proteins?
Essential or desirable attributes of candidate: Background in biochemistry, medicinal chemistry, physiology, biology or a related subject.
Supervisor: Dr. Paul Witting
Project Description: There is now considerable evidence for a key role for oxidative stress in tissue hypoxia induced by periods of reduced blood flow (termed ischaemia). Evidence has been presented for the formation of oxidation products derived from lipids and vitamins, both in vitro and in vivo. These oxidation products are believed to accumulate through the action of damaging free radicals. Such oxidation products are capable of inhibiting key cellular enzymes, altering cell redox status, and depleting antioxidants. More importantly, there is a body of evidence to support the idea that oxidation products can promote cellular dysfunction.
During a heart attack blood supply to heart muscle is significantly impaired and procedures that re-establish blood flow are susceptible to promoting damage to heart tissues through a process termed ischaemia reperfusion. We have shown that a cardiac protein, myoglobin, may play a role in promoting myocardial dysfunction through promoting tissue oxidation.
This project will provide an understanding of how oxidants produced by myoglobin can impair myocardial function at both the level of cardiac myocyte cell function and the intact heart. Such studies are an essential precursor to studies designed to prevent such damage. In particular we wish to:
- Quantify the extent of tissue damage in isolated perfused hearts.
- Demonstrate that the oxidation markers are specific to myoglobin-derived oxidative stress (through analyses for lipid oxidation specific to myoglobin oxidants).
- Investigate the mechanisms of myocyte dysfunction induced by ischaemia reperfsion (through determining intracellular events that lead to cellular dysfunction).
- Determine whether, and to what extent, the inhibition of myoglobin-derived oxidants can reverse ischaemia reperfsuion damage in isolated perfused hearts.
Contact: Dr Paul Witting,
Vascular Biology Lab, ANZAC Research Institute
Tel: +612 9767 9103
Email:
Key references:
Witting et al. Biochem. Biophys. Res. Commun., 2001, 286, 352, Jung et al. Biochem. Biophys. Res. Commun., 2001, 286, 419, Witting et al. J. Biol. Chem. 2001, 276:16540-7,
Witting et al. Chem Res Toxicol. 1999 12, 1173.
- Witting et al. Biochem. Biophys. Res. Commun., 2001, 286, 352,
- Jung et al. Biochem. Biophys. Res. Commun., 2001, 286, 419,
- Witting et al. J. Biol. Chem. 2001, 276:16540-7,
- Witting et al. Chem Res Toxicol. 1999 12, 1173.
Project 2: What is the composition of fragments of coronary plaque obtained from patients undergoing primary balloon angioplasty?
Essential or desirable attributes of candidate: Background in biochemistry or medicinal chemistry, biology or a related subject
Supervisors: Dr Paul Witting, Dr David Brieger and Dr Harry Lowe
Project Description: It is known that there are elevated levels of oxidised and modified proteins in a range of different diseased human tissues (e.g. atherosclerotic human arteries) when compared to normal tissues. The identity of some of these oxidised products have been examined using HPLC and spectroscopic techniques, and is consistent with the involvement of radical (one-electron) - and two-electron oxidation - (e.g. peroxides, hydrogen peroxide and hypochlorite) reactions. The accumulation of these oxidised or modified materials within cells has been hypothesised to play a role in cellular dysfunction in a number of diseases and to also play a key role in normal tissue ageing.
During balloon angioplasty plaque material can be dislodged and travel in the blood-flow. Whether these fragments from culprit atheroma cause secondary damage to vascular tissues is not known. For example, approximately 20% of all patients undergoing balloon angioplasty to reverse acute ST-elevated myocardial infarct (MI) fail to regain adequate blood flow after successful angioplasty. Interestingly, deploying a filter as part of the angioplasty procedure can capture the dislodged plaque material.
We aim to examine the composition of plaque material obtained from humans by filter capture. The proposed program will examine the levels of oxidized and unoxidised lipids and antioxidants as well as select protein oxidation products contained in the plaque material. In a second component to the study, endothelial cells will be exposed to the captured plaque materials to determine whether such material can promote endothelial cell dysfunction. These studies will involve a wide range of techniques including chemical kinetics, spectroscopy (UV, EPR), HPLC analysis, enzymatic assays and cell work, in order to provide a detailed evaluation of the potential for plaque to promote vascular dysfunction in an acute setting of myocardial infarct.
Contact: Dr Paul Witting
Tel: +612 9767 9103
Email:
Key references:
- Suarna et al. Arterioscler Thromb Vasc Biol. 1995 15, 1616,
Witting et al. J Clin Invest. 1999, 104, 213.
Project 3: In vivo investigations of coronary disease
The Department of Cardiology has ongoing research studies in the detection of myocardial dysfunction using echocardiography, the detection of coronary disease and coronary bypass disease using CT scanning, and the cellular mechanisms of atherosclerosis. New projects being planned include the in vivo study of high density lipoprotein (HDL) metabolism in man, and, in collaboration with Dr Witting of the Vascular Biology laboratory of the Anzac Institute and colleagues from the Department of Cardiology, the detection of myocardial injury using biomarkers of oxidative damage.
Contact: A/Prof Len Kritharides
email:
Project 4: Identification of mediators of fibrinolysis in plasminogen deficient mice.
Plasminogen is the major mediator of fibrinolysis, yet mice deficient in this protein survive to adulthood, suggesting the existence of physiologically important non-plasmin mediators of fibrinolysis. The purpose of this project is to characterize these non-plasmin mediators of fibrinolysis, using plasminogen deficient mice. In our current studies, we are using biochemical techniques to identify potential fibrinolytic proteins in the plasma of these animals. We are also analyzing their white cells, which appear to have enhanced lytic activity in the absence of plasminogen.
Techniques routinely employed include reverse transcriptase polymerase chain reaction (to confirm plasminogen deficiency in the mice), SDS-PAGE zymography and mass spectrometry (for peptide mass matching and sequence definition). The plasminogen deficient mouse model is available at the ANZAC Research Institute
Essential attributes include a background in biochemistry, molecular biology or a related subject
Contact: Dr Paul Witting
Tel +612 9767-9103
email:
A/Prof David Brieger
Tel: +612 9767-7358
email: davidb@email.cs.nsw.gov.au
Project 5: Gene targeting: Novel ways to improve outcomes in heart attack
Acute myocardial infarction (AMI) and its sequelae are an increasing problem in terms of morbidity, mortality and healthcare costs in Australia and the industrialised world. It is also increasingly recognised that the focus to date, of attempting to restore normal epicardial blood flow, addresses only one facet of the pathogenesis of AMI. Strategies directly protecting ischemic myocardium are therefore being keenly sought. A gene therapy approach to “myocardial protection” is one such method, creating much interest.
Using a rat model of ischemia-reperfusion, we are creating AMIs, and examining novel genes implicated in this process, looking for ways to block these genes to reduce infarct size and provide myocardial protection
Desirable Qualities: experience with small animals. Molecular biology skills.
Contact: Harry Lowe
email:
PAPERS:
- Lowe HC, Mac Neill BD, Van de Werf F, Jang IK. Pharmacologic reperfusion therapy for acute myocardial infarction. Journal of Thrombosis and Thrombolysis 2002;14:179-96
Project 6: Developing novel animal models of in-stent restenosis.
In-stent restenosis remains a significant problem within cardiovascular medicine, lately being treated using drug-eluting stents. Pre-clinical testing of novel stents and drug-coatings require careful testing using animal models, which are often expensive and time-consuming. More straightforward animal models are required; we are therefore investigating these.
Desirable Qualities: Techniques routinely employed include dissection of small animals including rats and rabbits, tissue embedding and sectioning, inverted fluorescence and standard light microscopy, quantitation of immunoactivity using video capture techniques. The ANZAC Research Institute has an up-to-date animal house for the housing and husbandry of small research animals.
Contact: Harry Lowe
email:
PAPERS
- Lowe HC, James BD, Khachigian LM. A Novel Model of In-stent Restenosis Using the Rat Aorta. Heart in press
Lowe HC, Schwartz RS, MacNeill BD, Jang IK, Hayase M, Rogers C, Oesterle SN. The porcine coronary model of in-stent restenosis: current status in the era of drug-eluting stents. Catheterization and Cardiovascular Interventions 2003:60:515-23. - Lowe HC, Oesterle SN, MacNeill BD, James B, Chesterman CN, Khachigian LM. Overstretch Stent Injury to the Rat Aorta Leads to In-Stent Restenosis. American Journal of Cardiology 2002;89:1010
- Lowe HC, Oesterle SN, Khachigian LM. In-stent restenosis: Current status and future strategies Journal of the American College of Cardiology 2002;39:183-93
Project 7: Vein graft stenosis
Symptomatic vein graft atherosclerosis remains a disease process with high morbidity, mortality and healthcare costs. Surprisingly, the precise nature of this disease process remains unclear. This study uses novel immunohistological techniques to carefully characterise atheromatous plaque retrieved using Distal protection devices in 50 patients undergoing percutaneous vein graft intervention. It is hypothesised that patients presenting with symptomatic vein graft atherosclerosis have a high prevalence of immunohistologic indices of plaque instability, and that these indices of plaque instability are increased in patients with acute coronary syndromes compared to those with stable angina. This proposal will therefore provide for the first time, a detailed immunohistologic examination of vein graft atherosclerotic plaque, using a methodology not previously reported in this context. The information provided will give novel insights into atherosclerosis and plaque instability in vein graft disease.
Techniques routinely employed include dissection of small animals including rats and rabbits, tissue embedding and sectioning, inverted fluorescence and standard light microscopy, quantitation of immunoactivity using video capture techniques. The ANZAC Research Institute has an up-to-date animal house for the housing and husbandry of small research animals.
Essential attributes include a background in molecular biology or immunology or a related subject
Contact: Dr Harry Lowe
Tel: 0419141982;
email:
Dr Paul Witting
Tel: +612 9767-9103;
email: