Physics in a New Era An Overview (2001) / Chapter Skim
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6. Health and Biomedical Sciences
6. Health and Biomedical Sciences
Pages 107-115
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From page 107... ...
Over the years, the use of ionizing radiation has become more sophisticated, and it is highly effective for certain types of tumors. Recently, for example, the radiation transport absorption coefficients and results from the simulation programs used by nuclear weapons designers have been applied to the problem of optimizing radiation dose in cancer treatment.
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From page 108... ...
Focal tissue coagulation by laser is the standard nonsurgical treatment for a detached retina, and the reforming of the corneal surface shape (laser keratotomy) with laser radiation is a very effective treatment for nearsightedness that is now becoming standard.
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From page 109... ...
Probably the most striking acivance in medical diagnostics has been the development of remarkable imaging techniques. Our ability to look inside the living body noninvasively started with Roentgen's discovery of x rays about a century ago.
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From page 110... ...
have magnetic properties, and these subatomic magnets can be aligned by a very strong magnetic field; how fast the tiny magnets line up depends on their surroundings, and this is exploited by MRI to produce images of tissue in the living body. Certain radioactive agents that have been injected into the bloodstream, like technetium-99, emit photons, and so brightness of the "light" emitted is used by SPECT to tell how much of the agent is present and therefore how much blood is flowing to that region.
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From page 111... ...
Researchers are using these high-resolution scanning techniques, which are sensitive to local brain metabolism or even to local concentration of complex psychoactive biochemical molecules that are thought to regulate brain function, to diagnose and guide treatment for a number of mental illnesses and for some forms of drug addiction. For example, brain scans have identified depressed metabolic rates and regions of abnormal biochemical concentrations in those regions of the brain associated with impulse control.
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From page 112... ...
In the image, the red pixels represent activity modulated during the attend-right phase of the experiment, and the green pixels, activity modulated during the attend-left phase. The red region labeled MT is the cortical area specialized for detecting movement.
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From page 113... ...
It is the application of physics techniques such as x-ray crystallography that allows determining the structure of viruses and identifying candidate sites on a virus to mimic with a therapeutic molecule. This rational drug design is now a major aspect of research at the many synchrotron radiation facilities that have been developed by the physics community in the past decade.
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From page 114... ...
Kinesin is a molecular motor, one of dozens of different sorts of specialized protein motors that are responsible for all forms of biological movement in all living organisms, from bacteria to humans. The most familiar manifestation of molecular motors at work is our ability to generate force with our muscles, but the beating of our heart, the tension of blood vessels that sets our blood pressure, the division of one cell into two during growth, and the movement of molecular cargoes -- from one place in a cell to another are all jobs that depend on a variety of molecular motors.
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From page 115... ...
The most familiar manifestation of these motors at work is muscle contraction and the pumping of the heart, but molecular motors are essential for the jobs performed by all cells, from the dividing of cells to produce replacements for cells that die to the carting of essential chemicals to where they are needed in the brain (see sidebar "Optical Tweezers". Unraveling how these motors work has required developing clever physical methods to measure the motions of single protein molecules over distances that are smaller than can be seen with microscopes.
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