18 December 2008

I gave up my body for research

For most of us, the idea of becoming a medical experiment conjures up Frankenstein-like images. But Health24's Carine Visagie discovers that it's both interesting and rewarding.

For most of us, the idea of becoming a medical experiment conjures up Frankenstein-like images.

There's the story of a friend of a friend of a friend who, desperate for spare cash, booked himself into a UK hospital as a medical research subject. Thinking that he would only have to pop a few pills and watch for side effects, he was shocked to find that something totally different was in store for him: the researchers promptly cut off one of his toes and sewed it back on again as part of a new, experimental procedure.

Now whether this story is really true or not, we'll probably never know. But what I do know is that, as a result, I definitely had a skewed impression of what's expected of research subjects. Fortunately though, this image has now been replaced by a much better one.

I recently took part in a study conducted by the Department of Human Biology of the University of Cape Town (UCT) in which insulin resistance and microvascular reactivity was measured in a group of South African women. It was an extremely interesting experience during which I learnt a few useful things about myself. Plus, it felt great to contribute to science.

Study background
Researchers know that the microvascular system – in other words, the blood vessels, blood and the morphologically associated nerves – may provide early indications of disease risk, even in healthy people.

By studying these relationships in healthy women, with widely varying health habits and body-fat levels, the UCT researchers aimed to gain a better understanding of the factors that may influence microvascular function, and which thereby predispose certain people to an increased risk for heart disease and diabetes.

One of the main goals of the study was to measure vascular reactivity – or the ability of the blood vessels on the surface of the arm to change in diameter – in a group of women between the ages of 18 and 40 years.

The second goal was to link differences in vascular reactivity to other measures of health risk and health behaviours. These included body-fat levels, body-fat distribution (waist measure), blood pressure, blood glucose and insulin levels (as a measure of diabetes), metabolic rate and fat oxidation, dietary fat intake, regular physical activity and family history of certain diseases.

What it entailed
All in all, I had to clock in at the Sports Science Institute in Newlands on three different occasions.

The first visit was just to familiarise me with the aim of the study and what to expect. I was asked to complete a questionnaire on my health status, as well as my exercise and dietary habits. I was taken on a brief tour of the lab, and then lead researcher Paula Pienaar measured my blood pressure, height, weight, and hip and waist circumference.

In preparation for my second visit, Paula asked me to skip breakfast and refrain from eating anything from 10pm the previous evening. Fortunately, our meeting was scheduled for early morning, before the hunger pangs really began to set in.

During this visit, I was asked to rest quietly for 30 minutes on a bed in the lab, after which measurements were made of the air that I breathed in and out. This was done through a Perspex bubble, with a good air flow, that was placed over my head. Paula explained that this so-called "ventilated hood" measured how much energy my body was using and how much fat I was burning while resting (in other words, my resting energy expenditure). I was also kitted out with a heart-rate monitor, which gave the researchers feedback on my "fight-or-flight" nervous-system activity.

Next up was a test to measure my body composition, specifically to get an indication of my body-fat percentage. This was done by means of dual X-ray absorptiometry (DXA). I simply had to lie down on a flat surface for about 10 minutes, while a big machine scanned over my body.

The third stop during my second visit was to have blood drawn. This was done to measure my glucose and insulin levels and was the only invasive part of the research.

A few days later, I checked in for my third visit. This mainly involved the measurement of my microvascular reactivity. After a 20-minute rest in the examination room, the skin on my forearm was prepared with an alcohol swab and some distilled water, after which Paula gently rubbed my skin with sandpaper to ensure that the equipment "read" a signal from my arm.

Hereafter, six different measurements – each lasting 7 minutes – were done. Two different solutions were placed in a little disc on my arm, and these solutions moved through my skin painlessly via a small electrical current. My blood flow was measured, using a laser-imaging device.

My results
A few weeks after the tests were completed, Paula gave me the good news that I was in perfect health. At the risk of boring you with the nitty-gritty details, let's just suffice to say that my blood pressure, waist circumference, glucose, free fatty acids and insulin levels were where they should be.

I was also extremely chuffed to find out that my diet was absolutely spot on: a carbohydrate intake of 56.7%, a protein intake of 17.39% and a fat intake of 25.82%. What's more, Paula surprised me with the news that I actually had a fast metabolism.

But what really interested me – and what really made taking part in the research worth my while – were two things: 1) the DXA scan showed that my bone density was too low in my spine; and 2) my body fat percentage was too high.

While I was aware that I was a bit overweight, I definitely didn't know that my bone density was below average. Now at least I know that I should exercise harder and make doubly sure that I eat two to three portions of dairy every day.

The verdict
While Paula and her fellow researchers are still analysing the results, they know at this stage that there's a definite association between insulin resistance and microvascular reactivity – thanks to the tests conducted on us.

It feels great to have played a part in this, and to have contributed to medical knowledge that might one day help save lives. I'm definitely putting my name on the list for more experiments in 2009. Care to join me? Then watch this space.

- (Carine Visagie, Health24, December 2008)


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