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...Sloan-Kettering in New York City. "Over 1 cm, and I lean very strongly toward additional treatment." A close look at the tumor cells will provide other clues, says Dr. William McGuire, chief of medical oncology at the University of Texas Health Science Center at San Antonio. Misshapen cell nuclei, abnormal amounts of DNA or an accelerated rate of cell division are all bad signs, suggesting a need for chemotherapy or tamoxifen. Newer tests include examining tumor cells for extra copies of cancer-causing genes or excess amounts of an enzyme called Capthepsin D, which seems to play a role...
...physics. Perhaps the greatest milestone in this quest has been the quark model of matter. In the early 1960s, theorists proposed that the scores of known subatomic particles were really composites, made up of just a handful of smaller particles. Even protons and neutrons, the major components of atomic nuclei, could be described as being made of these more fundamental objects, called quarks...
Their work closely paralleled the discovery of atomic nuclei. In 1910, Ernest Rutherford fired alpha particles (fragments of helium atoms) at targets of gold foil. Most passed through, but some bounced back, making it clear that there were dense concentrations of matter within the foil. In the Stanford experiments, electrons were fired at protons and neutrons. The way the electrons bounced off these particles showed that the latter were not uniformly dense but made up of tiny concentrations of matter -- the quarks...
Each gene consists of a segment of the DNA that is found in the nucleus of every one of the body's 100 trillion cells (with the exception of red blood cells, which have no nuclei). And each gene is responsible for the manufacture of a particular protein that contributes to either the structure or the functioning of the body. If the gene is defective, protein synthesis will be faulty and a deformity or genetic disease will result...
Epidermal cells become malignant when the DNA in their nuclei is altered, causing them to divide uncontrollably and form tumors. The transformation of DNA can be caused by repeated X-ray exposure, burns, infectious disease or frequent contact with certain chemicals. But by far the most common culprit is the sun's ultraviolet light. After years of exposure to sunlight, the damage becomes visible first as small, scaly, precancerous spots called keratoses, usually on middle-aged or older people and in areas of the skin generally not protected by clothing. These spots can turn malignant, becoming translucent basal-cell nodules...