Download Medicinea5

III. TECHNOLOGY MILESTONES IN HEALTH AND MEDICINE
III.8. Cancer Chemotherapy
Evolution of cancer chemotherapy
The use of chemicals to treat cancer (cancer chemotherapy)
began in 1942 with the clinical use of nitrogen mustards by
Louis S. Goodman and Alfred Gilman. Drugs which block
folic acid (also called antimetabolites) were also developed.
Aminopterin (1947) was effective against leukemia, but its
adverse effects on white blood cells quickly led to its
replacement by methotrexate. In the 1950s, George
Hitchings and Charles Heidelberger developed the
antimetabolitic
mercaptopurine
for
leukemia
and
Fluorouracil for gastrointestinal and breast tumors.
Cytotoxic drugs
Cytotoxic drugs (or drugs which are poisonous to cells) were
isolated from plants and first introduced into cancer
chemotherapy in 1963. These anti-cancer drugs work on the
principle that rapidly proliferating cells, such as neoplastic (or
cancerous) ones, are more susceptible to damage by cytotoxic
drugs. Several variations include vinca alkaloids (vincristine and
vinblastine) isolated from periwinkle plants and podaphylotoxin
isolated from mayapple in 1970. Taxol was isolated from the
pacific yew in 1971 and developed to treat advanced breast
cancer and lung cancer in the early 1990s.
Tamoxifen
Tamoxifen, a synthetic molecule developed in 1971, was
introduced in 1977 to treat breast cancer by slowing the growth
of estrogen-dependent tumors. High estrogen levels promote
the cell proliferation in breast tissue, so this type of
chemotherapy blocks the natural hormones that can stimulate
growth of cancer cells. Megestrol is a synthetic derivative of
the naturally occurring steroid hormone, progesterone, which
functions in a similar manner and is used in the treatment of
recurrent breast tumours.
Mammographic
image of a breast
tumour
Personal
monitoring of
breasts promotes
early diagnosis
III. TECHNOLOGY MILESTONES IN HEALTH AND MEDICINE
III.9. Novel Healthcare Materials
Artificial limbs and medical devices
Modern artificial limbs and organs, replacement joints,
contact lenses and hearing aids, and biomaterials which
are crafted from specialized plastics and other high-tech
materials have all been produced through chemistry. By
manipulating the structures of molecules and creating new
ones, chemists and engineers have developed new
medical materials that are strong, flexible, and durable. A
few such medical devices include the 1945 artificial
kidney, the 1950s prosthetic heart valves, and the 1982
surgical implantation of a permanent artificial heart. Plastic
contact lenses were introduced in 1956, and soft bifocal
contacts were refined in 1985.
Artificial
heart
valves
Artificial heart
Medical equipment
Chemistry is used to manufacture nearly all of
the plastic and vinyl medical devices used in
today’s hospitals and health care clinics. Today’s
medical equipment must be durable enough for
daily use while helping to create a clean, sterile,
and germ-free environment. Many routine
medical
processes
utilize
state-of-the-art
diagnostic equipment, stethoscopes, bandages
and other novel fabrics, syringes, surgical
instruments, blood bags, and plastic supplies that
are produced through chemistry. Even diapers
contain hygroscopic polymers that prevent
inflammation of the sensitive skin of babies.
Disinfectants and bleach
Chemistry makes it possible to sanitize your home, breakdown
mold and mildew, and remove stains. In the early 1900s, chemists
focused on controlling bacteria and cleaning clothes and home
surfaces effectively. In 1913, researchers developed a formula for
bleach that was affordable and easy to use. Today, bleach is a
household commodity and an effective disinfectant which
eliminates billions of germs and bacteria. Chlorine is also a
powerful weapon against diseases caused by viruses and bacteria
in homes, hospitals, and other buildings. Ignatius Semmelweis,
the Hungarian gynecologist, was the first to introduce hand
washing with chlorine water to his department in 1847.