Free radicals and the heart - The chemistry of almost everything (12/31)

Uploaded by OUlearn on 03.09.2009

Not everyone worries about their health
but I know a lot of you do.
So you may like to know
that two of the main sources of free radicals in our environment
are sunlight and tobacco smoke.
They're such difficult things to study.
They're only around for a few millionths of a second,
you need extremely complex technology for measuring them, identifying them,
looking for the fingerprints of their activity.
And it really is new technology.
In the heart field it's really only been studied
for the last 10 or 15 years.
So one of the ways in which we study
the effect of free radicals in the heart
are to take single heart cells,
isolated from a whole piece of tissue,
perhaps from a sample in the operating room,
study it under the microscope
and monitor many of the activities that you would see in a normal heart.
Included in the fluid which is going round the cell,
providing the oxygen and the glucose, there are photo active agents
which when illuminated with a particular colour of light
will generate free radicals.
What then happens is that these radicals,
although they're only there maybe for a millionth of a second,
will start attacking the membranous coating on the outside of the cell.
They will start to oxidise fats in the membranes.
They will start modifying proteins.
The cell may start twitching, it may start contracting bizarrely,
and eventually, if the damage is enormous,
the cell will being to round up
and go from this beautiful rod shape down to an amorphous kind of ball
and that's exactly what happens during a heart attack.
One major killer in heart disease
is what is known as reprofusion injury -
when a heart that's stopped starts pumping again minutes later,
bringing a rush of oxygenated blood to the starved heart tissues
and a burst of radicals along with it.
What you're seeing here is a piece of isolated heart tissue
beating away, completely removed from the body.
In these experiments
we will suddenly induce a burst of free radicals
and you will see a transition of a normal and regular slow heart rhythm
into a very, very rapid one
which will then deteriorate into a state of complete chaos.
That's called ventricular fibrillation and that kills you.
We know that those radicals are only present
for a few millionths of a second
but in that time, they can do sufficient damage
to cause perhaps a lethal heart attack,
a disturbance of cardiac rhythm
which would kill a patient in two or three minutes.
You have other effects which take longer to manifest themselves.
Possibly in diseases like cystic fibrosis
where the lack of antioxidant defences
slowly builds up accumulative injury in the tissue
which takes it toll with time.
At the extreme end of the spectrum, we all grow old.
And much of the ageing process,
the withering of skin, the changing of colour,
the changing of the texture of connective tissue,
that is all an accumulative effect of radical attack
over perhaps a century.
Some of the most healthy foods.
Halibut - first on the menu.
Its oils are rich in vitamin D, good for your bones.
Liver - lots of goodness here but you don't need to eat it often.
A single serving gives you a month's supply of vitamin A.
Curry powder- you need iron? Forget spinach.
Take a takeaway curry.
Cheese- calcium is vital for your bones and muscles.
All you need is a daily serving of hard cheese.
Fruit - you can enjoy a selection
but 100 years ago sailors had to suck on limes to get their vitamin C.
Brazil nuts - you need just a dash of selenium for the body's defence.
One and half brazil nuts gives you a daily dose.
And that's six really healthy foods.