An abnormal enlargement of the thyroid gland, called a goiter, can cause breathing difficulty and destroy the gland. Kocher explained the functioning of the gland and its relation to metabolism. Most importantly, Kocher’s work showed that physicians must leave an important part of the gland in place during surgery. He reduced the mortality of thyroid surgery significantly.

In 1921, Banting conducted research with Macleod, along with Charles Best, to prove that a substance called Trypsin degraded the body’s natural insulin production. The researchers stopped Trypsin production in dogs, allowing them to extract insulin for treating suffering from diabetes.

Karl Landsteiner and Murray developed a technique using radiotherapy and immunosuppressants to discourage the body’s tendency to reject donor organs.

After Robert Koch discovered that tuberculosis is caused by a bacterium, in 1943 Selman Waksman and colleague, Albert Schatz, isolated streptomycin from this bacterium, which proved an effective medicine against tuberculosis.

Nitric oxide as a signaling molecule in the cardiovascular system (leading to development of sildenafil citrate and similar drugs)

Discovery of magnetic resonance imaging (MRI) technology.

Scientists define genomes that contain ribonucleic acid (RNA) that can enter host deoxyribonucleic acid (DNA) as retroviruses. They discovered a retrovirus, later named Human Immunodeficiency Virus (HIV) that caused Acquired Immunodeficiency Syndrome (AIDS). This revelation led to improved treatments for those diagnosed with AIDS.

Some couples experience fertility difficulties. In the late 1970’s Edwards developed the concept of removing female eggs and fertilizing them in test tubes. The first in vitro fertilized birth took place in 1978.