环球英语 — 152：Changing Blood Groups
Voice 1
Hello, I’m Mike Procter.
Voice 2
And I’m Ruby Jones. Welcome to Spotlight. This programme uses a special English method of broadcasting. It is easier for people to understand, no matter where in the world they live.
Voice 3
“My name is Anna. I am just a normal person. But I help to save many people’s lives. How? Well, three times a year, I give blood. To do this, I go to my local blood donor centre. At the centre, the health worker asks me some questions. She wants to make sure that my blood is free from any harmful bacteria. Then, I lie down on a narrow bed. Another health worker places a needle into my arm. A tube leads from the needle to a machine. Slowly, the machine takes out some of my blood - almost half a litre! A system of tubes and plastic bags separates the blood into its different elements: red cells, white cells, platelets and plasma. Doctors can use these four elements to treat different medical problems. So one half-litre of my blood could help four different people!”
Voice 1
There are many people around the world like Anna. They know that their blood can save lives. This is because doctors depend on a ready supply of blood when they operate. They may need to it to replace a patient’s blood, lost during the operation. And, some people suffer from unusual medical conditions. They often need new, clean blood because their own blood is infected. So, it is important for hospitals to have a large supply ready at all times. And there is always a demand for new people to give blood.
Voice 2
In theory, the process is simple. People give some blood. Health workers then store the blood under controlled conditions. It is then ready for use when the doctors need it. But in real life, it is not that easy. Doctors cannot just give any kind of blood to their patients. The reason for this is genetic. The genes passed on to us from our parents dictate what our blood group will be. If a person receives blood from the wrong blood group, it could have a bad effect on their health. It may even result in death. Health workers must supply patients with blood that fits their blood group.
Voice 1
There are four kinds of blood group: O, A, B and AB. The most common blood kind, or type, is O. Any patient needing fresh blood can receive type O. Scientists believe that type O is the oldest blood group. They say that A and B groups developed from the O blood type as human history developed. Later, people moved around the world. They often married individuals with a very different genetic history. The scientists believe that group AB formed by genetic mixing among people with other types.
Voice 2
Type A blood contains a particular kind of sugar molecule. This sugar molecule attaches itself to the surface of the red blood cells. And it is an antigen - it can make the body react as if it is being attacked by harmful bacteria. This is what would happen if doctors gave B or AB type blood to someone with blood type A.
Voice 1
Type B also has sugar molecules on its red blood cells - but a different kind of sugar from type A. These sugar molecules are also antigens. However, in a person with type B blood these antigens would reject type A or AB blood.
Voice 2
It may be no surprise to hear that AB blood contains both A and B type sugar molecules! And both sugar types act as antigens in AB blood too. People with type A or type B blood cannot accept type AB. But some people with type AB blood can accept any type of blood.
Voice 1
Well, we can see that different blood groups may cause problems when it comes to treating patients. But a new scientific discovery may be about to change all that. Doctors in Denmark and Sweden have developed a new medical process - a way to change blood types A, B and AB into type O. Remember, type O can be given to anyone. So, how is this change possible?
Voice 2
The process seems very simple. The scientists searched different bacteria for some enzymes. Enzymes help to speed up chemical processes. The scientists mixed some of these enzymes with blood samples. And they found that two particular enzymes produced interesting results. These enzymes cut off the sugar molecules from the surface of the red blood cells. After one hour, blood samples of type A, B and AB were all free from sugar molecules. They had changed into type O blood.
Voice 1
The processed blood still needs to be tested on patients. But the scientists are very hopeful about the future of this discovery. Professor Henrik Clausen, from the University of Copenhagen in Denmark, led the research. He said,
Voice 4
“We hope that we can soon move this new process from the laboratory to the hospital. This may improve blood supply. And it may also improve patients’ safety when they receive blood transfusions.”
Voice 2
People’s ethnic origin influences what blood group they may be. Most people on the American continent have type O. Type A blood is very common among people from Central and Eastern Europe. Many people of Chinese or Asian origin have type B. And in Japan, China and Pakistan, ten [10] percent have the most rare blood type, AB.
Voice 1
In the 1970s, a Japanese writer called Masahiko Nomi wrote a book. This book suggested that blood types influence the way that people think and act. For example, people with type O blood may be more friendly, type A people may be quieter, type B people - more independent and type AB people - more serious minded. Many Japanese people are very serious about this theory. They may even ask about a person’s blood group when they search for someone to marry! But others believe that blood group is purely a health matter.
Voice 2
Doctor Peter D’Adamo is from the U S A. He wrote a book called ‘Eat 4 Your Type’. The book says that our blood groups should influence what we eat. For example, people with O type blood should eat more meat, but people with type A blood should eat more vegetables, and so on. Many people follow Doctor D’Adamo’s diet ideas. But some scientists say that these ideas have yet to be proved.
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