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The rhythms of life

Clocktower.

Shieak TzengDr Shieak Tzeng
The overarching goal of his research is to enhance the understanding of how the normal human body functions.

Dr Shieak Tzeng (Department of Surgery and Anaesthesia, Wellington) is fascinated by the big unanswered questions in the murky depths of the body's physiology. That's one of the main reasons he gave up medicine to engage in biomedical research.

"I don't regret doing a medical degree, but it wasn't for me. I was torn between research and medicine and was always thinking about my PhD research when on ward rounds. I wanted to ask questions – to explore – and biomedical research is an exciting and creative way to do that," he says.

So far it has paid off. The 28-year-old researcher has already made a name for himself as a former MacDiarmid Young Scientists of the Year Awards winner (in the Advancing Human Health and Well-being category) and, more recently, by winning an AMP Scholarship. He is also currently a National Heart Foundation Research Fellow.

He is investigating how the autonomic nervous system in the body regulates heart rate, blood pressure and pulmonary function. In 2010, with his wife and baby, he will continue this ground-breaking work at Harvard Medical School's Cardiovascular Research Laboratory. "I'm really looking forward to it. It's one of the best labs in this area and it'll mean that I can learn new techniques and skills to facilitate my research. It'll also be really stimulating to be working with a bigger group and leading international scientists."

Tzeng's research area is of wide interest internationally: trying to explain how the cardiovascular system is controlled through the autonomic nervous system and the brain, and what happens when that equilibrium goes out of balance.

He says that the autonomic system has two "arms" coming from the brain, two pathways which control the functions of our body: the sympathetic and parasympathetic system. The subtle balance of this system allows the heart rate to be regulated, amongst a host of other key physiological functions. "My research is working around four major questions: what determines that balance, what things can change it, how can we measure the activity non-invasively and what happens if cyclical body rhythms are lost, such as in heart failure?"

Tzeng has already established some fundamental relationships in this area and has had several papers published in major journals. These studies have elucidated new mechanisms by which the cardiovascular and respiratory systems interact, and have provided new insights into how heart rate, blood pressure and breathing rhythms are inter-related and what information they might tell us about underlying autonomic function.

Because much of the existing evidence is based on analysis techniques that Tzeng's research has shown to be unreliable and, because animal models are not particularly relevant to the human experience in this particular area, his more recent work has focused on people who have cardiovascular problems.

"We use traditional techniques like tilting people, putting cuffs around their neck to generate negative pressures and stimulating nerve receptors that are responsible for regulating the autonomic system. We combine these time-honoured methods with imaging and pharmaceutical interventions and measure the results."

Tzeng says the overarching goal of his research is to enhance our understanding of how the normal human body functions. "We can develop new technologies and show how our fancy new measures change with disease. But unless you understand at a very simple level what you're looking at – what it means and how it normally works – you won't get very far."

He hopes his research will contribute to the development of economical diagnostic tools (a bit like an ECG machine) that will be able to measure the activity of the autonomic nervous system, to be used in clinical settings to predict those patients who might require more aggressive therapy.

"I just love the whole research process," he says. "Challenging the conventional view and coming up with new approaches, then testing and trying them out ... When it works it's tremendously exciting!"

Funding

  • National Heart Foundation
  • Health Research Council of New Zealand
  • Wellington Medical Research Foundation