Transplanting Man’s Heart

On January 2, 1968, an amazing occurrence in the history of medicine took place. On that day a South African doctor, Christian Barnard, successfully transplanted a human heart into a man named Philip Blaiberg. The technique he used in performing his surgery had been developed in 1959.

Although very many organ transplants are still being performed, they are slightly less publicized today than they were in 1968 and 1969. The original feelings of success wore off quickly when the doctors discovered that they had not completely solved all the problems of such operations. One of the biggest problems is the fact that the patient's system is not always willing to accept a foreign organ. It works against, rather than with it. When this happens, the transplant is a fail­ure, and the patient's life is in danger. On August 17, 1969, Doctor Barnard's patient died because his body rejected his new heart.

The history of transplanting human organs began in the 1930s. The first attempts were made on the cornea of the eye. Since the cornea has no blood vessels, there was no necessity of typing the patient and donor's antigens. Most of these operations were successful.

Surgeons first tried to transplant a kidney in the early 1950s. To avoid the need for typing, the donor and recipient at that time were twins. For a number of years, such an operation was only successful when performed on twins. But by 1969, due to the development of agents that would prevent rejection, kidney transplants were made successfully on unrelated persons. If a patient survived the first three months after the operation, he was given an eighty percent chance of living

three more years or longer. The liver, pancreas, and lung have been transplanted with success.

Throughout the history of medicine, doctors have worked to invent better methods of saving the lives of their patients. The steps they have taken to do this have been slow and often frustrating. Doctors and scientists are constantly confronted with new problems just when they think that old ones have been solved. In the field of heart transplants, doctors are now working to perfect artificial hearts that will keep patients alive until heart transplant donors have been found. An operation for this purpose was performed for the first time in the United States on April 4, 1969. The artificial heart kept the patient alive for two and a half days until it was replaced by a donor's heart.

An ultimate goal in heart transplant research is to make an artificial heart that can remain in the patient's body for the rest of his life. Many problems must be combatted in this search. The lives of many men are valiantly devoted to the task of saving the human heart. Perhaps in the near future they will completely succeed.(2321)

Watson and Crick Describe Structure of dna.

What is DNA?

DNA stands for deoxyribonucleic acid. This is a substance that is present in every living cell. However, each living thing has a different kind of DNA. The kind of DNA you have in your cells gives you all the features you inherit from your parents.

In the late nineteenth century, a German biochemist found that the nucleic acids, long-chain polymers of nucleotides, were made up of sugar, phosphoric acid, and several nitrogen- containing bases. Later it was found that the sugar in nucleic acid can be ribose or deoxyribose, giving two forms: RNA and DNA. In 1943, American Oswald Avery proved that DNA carries genetic information. He even suggested DNA might actually be the gene.

In 1948, Linus Pauling discovered that many proteins take the shape of an alpha helix, spiraled like a spring coil. In 1950, biochemist Erwin Chargaff found that the arrangement of nitrogen bases in DNA varied widely, but the amount of certain bases always occurred in a one-to-one ratio. These discoveries were an important foundation for the later description of DNA.

In the early 1950s, the race to discover DNA was on. At Cambridge University, graduate student Francis Crick and research fellow James Watson (b. 1928) had become

impressed especially by Pauling’s work. Meanwhile at King’s College in London, Maurice Wilkins (b. 1916) and Rosalind Franklin were also studying DNA. The Cambridge team’s approach was to make physical models to narrow down the possibilities and eventually create an accurate picture of the molecule. The King’s team took an experimental approach, looking particularly at x-ray diffraction images of DNA.

In 1951, Watson attended a lecture by Franklin on her work to date. She had found that DNA can exist in two forms, depending on the relative humidity in the surrounding air. This had helped her deduce that the phosphate part of the molecule was on the outside. Watson returned to Cambridge with a rather muddy recollection of the facts Franklin had presented, though clearly critical of her lecture style and personal appearance. Based on this information, Watson and Crick made a failed model. It caused the head of their unit to tell them to stop DNA research. But the subject just kept coming up.(1902)