Diabetes is a disease where there is too much sugar (glucose) in the blood.

Glucose enters your body from the foods you eat such as cakes, fruits, pasta and bread. Your body uses glucose as energy for everything you do.

The insulin peptide structure

Insulin is a hormone that is made in the pancreas when there is too much glucose in the blood. Insulin acts like a key that opens the doors that lets glucose move from the blood and into your cells. It is then used for energy.

When someone’s body loses its ability to produce Insulin, they have Type 1 Diabetes and when someone’s Insulin loses its ability to ‘open the door’ to their cells, they have Type 2 Diabetes.

Symptoms

• Frequent urination
• Dehydration
• Thirst

Problems caused by Diabetes

• Blindness
• Kidney failure
• Problems with legs and feet
• Death

Some facts about Diabetes…

Type 1 Diabetes

• Genetic (inherit from parents)
• Autoimmune condition (your immune system attacks your pancreas, leading to Diabetes)
• Begins when you are a kid
• Need to inject Insulin into your body everyday for treatment

Type 2 Diabetes

• Lifestyle (lack of exercise, obesity)
• Can happen at any age
• Need to live a healthier life, exercise more and sometimes take medicines for treatment.

Discussion Points: Diabetes is one example of where a biomarker test is used on a daily basis by patients. Here the focus is on self-management not diagnosis. Can you think of any other health issues that would benefit from such a strategy?

The “horse meat scandal” hit the headlines back in January when the food standards agency (FSA) in Ireland found beef burgers being supplied to supermarkets in the UK, had traces of horse DNA. This led to nationwide testing of products, and a range of processed beef products being taken off the shelves. As of the end of March, the FSA said 5,430 tests had been carried out in the UK, with 17 different products including Findus beef lasagne testing positive.

So how do we test for horse meat? One of the most reliable tests is called “PCR”. In PCR specific short pieces of horse DNA are used to bind to and detect any horse DNA in the product being tested. The test makes copies of the horse DNA found and these can then be counted in real time as they are produced a percentage calculated. Here the DNA is being used as the biomarker.

Horse meat itself is not a risk to humans, and is in fact sometimes on the menu in countries! However, if horse is being illegally put into food products, it may contain banned substances such as bute, a horse drug which can be harmful to humans (but only if we eat a lot!). It has made a lot of people worry about what is actually in their food and whether they can trust the label!

Wikipedia article:

http://en.wikipedia.org/wiki/2013_meat_adulteration_scandal

Dicsussion Points: The horsemeat issue is another use of biomarkers. Not only are they used in diagnosis, we exploit them in food quality tests and other areas. Can you think of anywhere else testing for a biomarker would be useful?

What are Biomarkers?

Biomarkers are biological characteristics which can be used to detect diseases. Researchers are interested in finding biomarkers because they can be used to help diagnose and treat patients.

Biomarkers are usually proteins found in cells or bodily fluids like blood or urine. By measuring the levels of these proteins doctors can assess how severe a disease is and detect improvements after treatment.

Example: HER-2 and breast cancer diagnosis and treatment

In some breast cancers the tumour cells have abnormally high levels of a protein called HER-2. HER-2 is a protein found on the cell surface which receives chemical signals to make the cell grow and divide. If cells have too much HER-2 the cells grow out of control, leading to cancer and tumour formation.

Detection: HER-2 positive cells are easily detected in biopsy material using a stain which shows high levels of HER-2 in dark brown. As these cells grow very quickly doctors know that HER-2 positive tumours need rapid treatment.

Treatment: Researchers designed a drug (Herceptin) which detects cancer cells with abnormally high levels of HER-2. Herceptin is an antibody which specifically binds to HER-2 proteins and tells the immune system that the cell needs to be destroyed.  Therefore the identification of HER-2 as a biomarker for a type of breast cancer has resulted in quicker and more effective treatment for HER-2 positive breast cancer patients.

Video of Herceptin in action http://www.youtube.com/watch?v=66z6BmeA00I

More about biomarkers http://en.wikipedia.org/wiki/Biomarker_(medicine)

Discussion Points: When would detecting biomarkers be useful? Do we need a biomarker for every health issue? Why are antibodies often used to detect protein biomarkers? Biomarkers aren’t always proteins. What else could be a biomarker? How could they be measured?