Medicine

E

Mental Illness

Even in the early part of the 20th century, mental illness was almost a sentence of doom, and mentally ill persons were handled with cruel confinement and little medical aid. In the latter half of the century, successful therapy for some mental illnesses has greatly improved the prognosis for these diseases and has partly removed their stigma.

The theories advanced by Austrian physician Sigmund Freud were among the first attempts to understand malfunctioning of the mind, but the methods of psychoanalysis advocated by Freud and modified by his followers proved ineffective for treating certain serious mental illnesses. Two early attempts to treat psychotic illness were the destruction of parts of the brain in a procedure called lobotomy, introduced in 1935, and electroconvulsive therapy, devised in 1938. Lobotomy and less severe forms of psychosurgery are now used only rarely, and electroconvulsive therapy is primarily a treatment for depressive illness that has not responded to drug therapy.

A new era in treatment of schizophrenia, a severe form of mental illness, began in the early 1950s with the introduction of phenothiazine drugs. These drugs led to a new trend, deinstitutionalization, in which patients were released from mental hospitals and treated in the community. Valium (see Diazepam) and other benzodiazepine drugs went into wide use in the 1970s for treating anxiety and other emotional illness. Late in the century, there was growing awareness about the importance of diagnosing and treating clinical depression, a leading cause of suicide. Advanced imaging techniques that show the structural and functional differences in the brains of people with certain mental illnesses have opened the door for new treatment options.

F

Genetics and Biotechnology

The discovery of genes and their role in heredity and disease was one of the most important medical advances in history (see Genetics). In 1953 British biophysicist Francis Crick and American biochemist James Watson identified the double-helix structure of deoxyribonucleic acid (DNA). This discovery helped to explain how DNA carried genetic information. In the 1960s American biochemist Marshall Nirenberg added key details about how DNA determines the structure of proteins.

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Indian-born American biochemist Har Gobind Khorana was the first to synthesize a gene in the laboratory in 1970, forging the way for scientists to develop ways to isolate, alter, and clone, or copy, genes. They applied these genetic engineering techniques to the diagnosis and treatment of diseases. Researchers identified genes associated with cancer, heart disease, mental illness, and obesity. With the genes identified, they worked on ways of modifying the genes to treat the disease. Gene therapy emerged as an experimental medical field that used genetically modified genes to treat diseases. In 2003 scientists completed the sequence of the human genome, in which they identified all the genes needed to make a human being (see Human Genome Project).

Genetic engineering techniques enabled production of scarce human hormones and other materials for use as drugs. A new biotechnology industry started producing these materials for medical use. Scientists also began genetically modifying sheep and other animals to produce drugs in their milk.

G

Endocrinology

In 1905, British scientist Ernest H. Starling introduced the word hormone to describe substances secreted by the endocrine glands that regulate body functions (see Endocrine System). The discovery of adrenaline, or epinephrine, in 1901 led to identification and isolation of other hormones. One of the most important advances was the discovery of insulin by Canadian scientists Frederick Banting and Charles H. Best and Scottish physiologist John J. Macleod in 1921. For years people with diabetes mellitus used insulin extracted from animal pancreases. In 1981, human insulin produced using biotechnology became available. American physicians made another major advance in endocrinology in 1949. They discovered that cortisone, an adrenal gland hormone, relieved inflammation. New discoveries about human sex hormones later led to the first birth control pills.

H

Pregnancy and Childbirth

Great advances were made in birth control with the improvement of intrauterine devices in the 1950s and the development of the birth control pill in 1960 by the American biologist Gregory Pincus. By the 1990s long-lasting hormonal implants and contraceptive injections such as Depo-Provera were developed. These options gave women more control in deciding whether to become pregnant. Voluntary sterilization, involving vasectomies in men and tubal sterilization in women, emerged as a popular way of permanent birth control. Unwanted pregnancies, however, remained a serious problem in the late 1990s. Researchers still sought more convenient and safer methods of birth control, including a male birth control pill.

By 1975 physicians were able to diagnose some congenital or inherited diseases before childbirth (see Birth Defects). Doctors take samples of placental cells (see Chorionic Villus Sampling) or of the amniotic fluid around the fetus (see Amniocentesis) to determine whether hereditary blood diseases, Down syndrome, defects of the spine, or other congenital diseases are present. Even the sex of a fetus may be known in advance.

In addition to advances in early diagnosis, progress occurred in identifying the causes of some birth defects. Excess alcohol consumption during pregnancy was linked to fetal alcohol syndrome, and inadequate intake of the vitamin folic acid was linked to spina bifida and other neural tube defects.

Advances in treating infertility, which prevents couples from having children, began with the world's first so-called test-tube baby born in the 1980s through in vitro fertilization. Other forms of assisted reproduction soon became available. Researchers in 1997 cloned a lamb from cells taken from an adult ewe. It led to speculation that human cloning could become another option in human reproduction.

I

Heart Disease

Heart disease emerged as one of the leading causes of death in Western countries by the end of the 20th century. Great advances occurred in diagnosis, treatment, and prevention of this widespread disease.

Diagnosis improved with the widespread use of cardiac catheterization in the 1950s. This procedure involves threading a slender tube into the heart to take measurements and identify blocked arteries. Less invasive diagnostic methods, such as thallium scans in which a special imaging camera detects the movement of thallium in heart muscle, provided additional diagnostic improvements.

These techniques led to a new era in surgical treatment of coronary heart disease, artery blockages that cause most heart attacks. Physicians began treating blocked coronary arteries with a variety of new techniques. The first bypass operation was performed in 1967 and involved the creation of a new route for blood supply to reach blood-starved heart muscles. In balloon angioplasty, developed in 1977, a deflated balloon is inserted into a narrowed artery. The balloon is then inflated at the site of the narrowing to widen it. Other surgical advances included replacement of diseased heart valves with artificial valves; implantation of pacemakers that maintain normal heart rhythm; use of temporary artificial hearts; and better methods for correcting hereditary defects in the heart.

New drugs were developed to treat angina pectoris, the chest pain of heart disease; high blood pressure; dangerous abnormalities in heart rhythm; and high blood cholesterol levels. Studies showed that drug treatment could reduce the risk of a heart attack or stroke. In the 1980s, aspirin went into wide use to prevent blood clots that cause many heart attacks. Emergency medical personnel also began using drugs that dissolve clots and stop a heart attack if given soon after symptoms develop.

Advances have been made in the prevention of heart disease. Studies have identified risk factors such as high blood pressure, high blood cholesterol, cigarette smoking, diabetes, obesity, and lack of exercise. Government health agencies and public health groups began public education programs to help people reduce heart disease risks. These preventive methods seem to be working—according to the American Heart Association, the death rate from coronary heart disease declined 26.3 percent between 1988 and 1998.