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Who discovered penicillin?

Penicillin was the first antibiotic, a special drug that is very good at killing bacteria. With antibiotics, many illnesses can soon be cured that were once incurable. Penicillin was discovered by accident by the British scientist Sir Alexander Fleming in 1928. He noticed that a mold which had formed in a dish in his laboratory was killing bacteria in the dish. From the mold, penicillin was later prepared. In 1938, Howard Floery and Ernst Chain found a way to make penicillin in large quantities.

Alexander Fleming returned to his research laboratory at St. Mary’s Hospital in London after World War I. His battlefront experience had shown him how serious a killer bacteria could

be, much worse even than enemy artillery. He wanted to find a chemical that could stop bacterial infection.

He discovered lysozome, an enzyme occurring in many body fluids, such as tears. It had a natural antibacterial effect, but not against the strongest infectious agents. He kept looking. Fleming had so much going on in his lab that it was often in a jungle. This disorder proved very fortunate. In 1928, he was straightening up a pile of Petri dishes where he has been growing bacteria, but which had been piled in the sink. He opened each one and examined it before tossing it into the cleaning solution. One made him stop and say, “That’s funny.”

Some mold was growing in one of the dishes. ...not too unusual, but all around the mold, the staph bacteria had been killed ... very unusual. He took a sample of the mold. He found that it was from the penicillium family, later specified as Penicillium notalum. Fleming presented his findings in 1929, but they raised little interest. He published a report on penicillin and its potential uses in the British Journal of Experimental Pathology.(1504)

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)

Cloning of an Adult Mammal.

When Dr. Ian Wilmut introduced the world to the world to the first successful clone of an adult mammal - a seven-month old Finn-Dorset lamb named Dolly - a new frontier in science opened wide.

When Dr. Ian Wilmut and his team from the Roslin Institute created a lamb named Dolly, they accomplished what many experts thought was a scientific impossibility. Unlike offspring produced in the usual fashion, Dolly does not merely take after her biological mother. She is a carbon copy, a laboratory counterfeit so exact that she is in essence her mother’s identical twin.

In 1996, Dolly became the first large animal to be cloned from genetic material extracted from an adult cell. Scientists inserted a cell from a ewe’s udder into an egg from the same animal after removing the egg’s DNA. The bioengineered embryo was implanted in the ewe’s womb and Dolly developed as a clone. Her birth at the Roslin Institute in Scotland was announced in 1997 and caused an international sensation.(839)

Henry Ford.

Bringing the Automobile to the Common Man

Henry Ford is a man who literally transformed the world. The car he built and the changes he made on the techniques of industrial production revolutionized the lives of people everywhere. At the height of his fame, in the 1920s, Ford was a name known universally.

Ford himself came from a humble farming background. Born July 30, 1863. in Dearborne, Michigan, near Detroit, young Henry hated almost everything about farming except the machinery. When he was 16 he went to Detroit to serve as an apprentice in a machine shop. He held a series of jobs and became completely knowledgeable of the way different types of machines operated. He began to experiment with internal combustion machines in his home workshop in 1891. He was one of many would-be- inventors working on plans for the automobile; and he discussed his project with other mechanics and businessmen working in Detroit. In 1896 Ford succeeded in building an automobile powered by a gasoline engine which he had built in his kitchen sink. Running on four horsepower, the car could reach a speed of 25 miles per hour.

Ford organized the Detroit Automobile Company in 1899 and produced a small number of cars before the company collapsed two years later. He designed and manufactured racing cars, and in 1900, raced one model at 70 miles per hour.

In 1903, at the age of 40, and with an investments 28,000, Henry Ford established the Ford Motor Company. The automobile was still considered a toy of the rich, and Ford set about to change this situation.

In the early years of the company's existence, Ford was involved in legal battles challenging patents which restricted his freedom to alter the internal combustion engine to better suit the car he wished to build. Winning a clear victory in the courts, Henry Ford established an early reputation as a foe of monopolies and the champion of the common man.

The Model T Ford was introduced in 1908. It was boxy and tinny-looking, as its nickname, the "Tin Lizzie," implied; but it was within the purchasing power of people who were not rich. It fulfilled the goal which Ford had set for himself:

"I will build a motor car for the great multitude. It will be large enough for the family but small enough for the individual to run and care for. It will be constructed of the best materials by the best men to be hired, after the simpliest designs that modern engineering can devise. But it will' be so low in price that no man making a good salary will be unable to own one— and enjoy with his family the blessing of hours of pleasure in God's great open spaces."(2166)

Henry Ford

Ford was able to lower the price of the Model T from the $850, which it cost when it first appeared, to $360 in 1916. He did this by introducing mass production assembly line techniques. In 1913 Ford conducted his first test of assembly line manufacture. He drew up the techniques which he had observed in a Chicago meat packing plant where an overhead trolley moved the carcasses of animals from one butcher to another: since each butcher had a special job, he could do his cutting work faster and more efficiently than when he had to cut up the whole animal by himself.

The assembly line revolutionized car production. A chassis that formely took 12.05 hours to build in the shop, now rolled off the assembly line in an hour and a half. This made it possible to triple the production of Model T's within three years.

Ford also introduced the $5.00 wage for an eight-hour day. Such a salary was unheard of in 1914, and he attracted both national and international attention when he began this practice. He also introduced a plan which allowed his workers to share in the profits of the company—the profit sharing plan which is used by many companies today.

Ford was a genuine folk hero to the American people. He represented the virtues of an older, simpler agrarian society— hard work, self-reliance, and thrift even though he contributed to the demise of agrarian life. He was a colorful figure, and stories of his love of running (long before the days of jogging) and his strange notions about diet (he sometimes ate grass sandwiches) were well known. People had an idea of who Henry Ford was—and he in turn, seemed to know what the American people wanted in terms of a product.

As owner of the Ford Motor Company, Henry Ford accumulated more than $1 billion. Between the years 1908 and 1947 when he died, he contributed more than $40 million to charitable causes, such as public hospitals, and research institutions. He established the Ford Foundation which continues to support various programs in education, media, and culture. And he constructed Greenfield Village, near his birthplace in Michigan, as a living museum representing the industrialization of America.(1810)


Date: 2015-01-29; view: 178


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