Despite the rapid progress of modern medical science, cancer remains an unconquered enemy of mankind. The Republic of China, however, has made a breakthrough recently in its cancer research. After a long series of experiments, Prof. Tun Ta-cheng of the department of biochemistry of the National Taiwan University has discovered that cancer cells, after being subjected to abrus agglutinin (AAG) may lead to the development of an antigen in the human body. This can be used as vaccine which has already produced strong immunity in animals. It keeps cancer cells in check, or even destroys them to some extent.
The professor's success is based on his studies of the jequirity bean, a red and black seed of a tropical plant that grows abundantly in southern Taiwan. When he started his research 30 years ago, he discovered that the bean contained four kinds of toxic protein which could destroy cancer cells.
Because the bean is poisonous to normal cells as well, it could only be used directly on cancer cells. As a result, treatment was only possible after the cancer cells had appeared.
For a long time, the risk in using the bean's proteins was greater than that involved in surgery. Always, when it was applied to cancer cells, it damaged normal cells as well.
It was only when Prof. Tun turned his attention to AAG, a fifth protein found in the bean, that he achieved his breakthrough. He discovered that while AAG can curb the growth of cancer cells, it has low toxicity for normal cells.
Most people have natural immunity to cancer which enables them to destroy between 100 and 200 abnormal cells a day. This immunity is reduced, however, as a person gets older or consumes too much medication. Once the number of cancer cells reaches a certain level, the body's antibody fail to control them. To increase immunity, the structure of the cancer cell's membrane must be changed so that antibody can attack it. In the past, X-rays, drugs and viruses have been used to achieve this, but with little effect.
To ensure the accuracy of his tests, Prof. Tun used a pure breed of guinea pig for injection with the proteins. After implanting cancer cells and allowing them to grow in the mice, he removed them and ran a test tube culture. The vaccine was made by adding AAG to the culture, and injected into another guinea pig before cancer cells were implanted in its body. Although tests showed that the mouse developed immunity and was able to destroy the cancer cells, several problems must be resolved before the treatment can be used on man.
Prof. Tun at first used cancer cells taken from patients during surgery to create his AAG vaccine for humans. Later, the vaccine was injected into the patients in the hope that it would arrest the growth of the tumor.
Clinical tests at the National Taiwan University Hospital at the beginning of this year, however, failed to show conclusive results. A careful review revealed that patients are too weak to develop immunity immediately after surgery. It usually takes two or three months for this to happen, by which time the cancer may have killed the patient.
Prof. Tun is now planning to use bacteria such as Bacillus Calmette-Guerin (BCG) to enhance the cancer patient's immunity. To prolong the life of the vaccine, he is planning to preserve cancer cells taken from humans either by tissue cultivation, freezing at a temperature of minus 70 Centigrade or implanting them in nude mice which have no immunity. The practicability of these treatments has yet to be proved by clinical tests.
Prof. Tun, 64, has been in the field of biochemistry for more than 40 years. After obtaining his Ph.D. in medical science from Kyushu University in Japan in 1945, he returned to his alma mater, the National Taiwan University, to conduct research work.
In 1948, he went to the United States to study at the department of biochemistry and the graduate school of enzymology at Wisconsin University for two years. Then he resumed his research work at the NTU, and under his supervision, the department of biochemistry has developed research work in nine areas--protein chemistry, nutrition, mycotoxin, carcinogenic substances, black-foot disease, cytology, genetics, food toxicology and anticancer drugs. He has helped the country to cultivate many young specialists in biochemistry.
Besides his research on the jequirity bean, he has also studied enzymes in rice, aflatoxins, and cooking oil. During his work, he discovered that improper fermentation may create aflatoxins in soy sauce which may cause cancer of the liver. He also proposed the addition of Vitamins B1, B2, and nicotinic acid to rice to improve public health. The professor said confidently: "As long as I am able, I will dedicate myself to improving the quality of human life in every possible way."
[Picture Caption]
Prof. Tun injects toxic protein vaccine in guinea pig, and right, shows the difference between a healthy mouse (left) and one suffering from cancer.
The jequirity bean (right) is a red and black seed of a tropical plant that grows abundantly in southern Taiwan (left).
The jequirity bean （right）
is a red and black seed of a tropical plant that grows abundantly in southern Taiwan （left）.
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