1930. Immunization against Viral Diseases

With the exception of smallpox, it was not until well into the 20^th century that efficient viral vaccines became available. In fact, it was not until 1930s that much began to be known about viruses. The two developments that contributed most to the rapid growth in knowledge after that time were the introduction of the electron microscope and the introduction of tissue culture as a means of growing viruses in the lab.

Once the virus could be cultivated with comparative ease in the laboratory, the research worker could study it with care and evolve methods for producing one of the two requirements for a safe and effective vaccine: either a virus that was so attenuated, or weakened, that it could not produce the disease for which it was responsible in its normally virulent form: or a killed virus that retained the faculty of inducing a protective antibody response in the vaccinated individual.

The first of the viral vaccines to result from these advances was for yellow fever, developed by the microbiologist Max Thieler in the 1930s. About 1945 the first relatively effective vaccine was produced for influenza; in 1945 the American physician Jonas E. Salk introduced a vaccine poliomyelitis and in 1960 an oral poliomyelitis vaccine, developed by the virologist Albert B. Sabin, came into wide use.

These vaccines went far toward bringing under control thee of the major diseases of the time, although in the case of influenza a major complication id the disturbing proclivity of the virus to change its character from one epidemic to another. Even so, sufficient progress has been made to ensure that a pandemic like the one that swept the world in 1918-1919, killing more than 15,000,000 people, is unlikely to occur again.

1967. Organ Transplantation

In 1967 surgery arrived at a climax that made the whole would aware of its medicosurgical responsibilities when the South African surgeon Christian Barnard transplanted the first human heart.

In 1964 James Hardy, of the University of Mississippi, had transplanted a chimpanzee’s heart into a man.

Research had been remorselessly leading up to just such an operation ever since Charles Guthrie and Alexis Carrel, at The University of Chicago, perfected the suturing of blood vessels in 1905 and then carried out experiments in the transplantation of many organs, including the heart.

1971. Ct Scan and mri Introduced

The use of X-rays in medicine was a huge breakthrough at the turn of the century. British engineer Godfrey Hounsfield came up with an improvement on the 70-year-old technology. It combined X-ray images with a computer.

Hounsfield called this technology a CT (computerized tomography) scan, also called CAT scan (computerized axial tomography). It was especially useful for looking at head injuries and brain problems, because it showed about 100 times greater detail in soft tissues than traditional X-rays. Hounsfield was knighted and won the 1979 Nobel Prize.

In the 1980s another imaging technique was added to the tools of medicine. Nuclear magnetic resonance is a technology that, using a gigantic magnet, can line up the protons- or nuclei of hydrogen atoms – in an object (or organism) to align with the north-south polarity of the magnet. A computer “reads” this to create an image in a process known as MRI, magnetic resonance imaging. MRI can give an image of any plane through the body, while the patient’s experience consists of lying still in a body-sized tube, and hearing the click of the machinery.