TAREA 13: PARKINSON'S DISEASE AND PAIN

A brain disorder mostly of the elderly, Parkinson's is characterized by trembling, rigid posture, slow movements and a shuffling, unbalanced walk. lt results from the degeneration of or damage to dopamine-containing neurons that originate in the substantia nigra of the brain and project into the basal ganglia. But the precise cause far Parkinson's is unknown and until recently it had no treatment. During the late 1950's, scientists associated the loss of dopamine with Parkinson's. They found that levodopa improves the symptoms of most Parkinson's patients.
To reduce gastrointestinal side _1_, levodopa is usually combined with the drug carbidopa. But the _2_ effects of levodopa gradually _3_, requiring the use of a _4_ of drugs including bromocriptine, pergolide and amantadine. The drug deprenyl may slow the _5_ of the disease. For some patients, an operation on the brain may _6_ tremor and rigidity but better _7_ are needed.

Recently, scientists _8_ reduced Parkinson's like symptoms in rats by injecting skin cells that have been _ 9_ engineered to produce dopamine in the basal ganglia. _1O_ have also transplanted adrenal gland and fetal brain _11 _, both of which produce dopamine, into the brains of Parkinson's patients. However, much basic _12_ must be completed before this strategy becomes useful for most _13_.

Researchers are now working with an animal model of Parkinson's, _14_ injected with a substance called MPTP, which has _15_ the doors to new approaches to tissue implants and other _16_.

Pain

How pain killers work. At the site of injury, the body produces prostaglandins which increase pain sensitivity. Some analgesics, such as aspirin, prevent the production of prostaglandins. lf there is a universal _17_, pain is it. Each year, more than 97 million Americans _18_ chronic, debilitating headaches, about with a _19_ back or the pain of arthritis- all at a total _20_ of some $80 billion. But it need not be that way. New _21_ about how chemicals in the body transmit and intercept _22_ have paved the way for new _23_ for both chronic and acute pain.

Until the middle of the 19th century, pain _24_ during surgery relied on natural substances such as _25_, alcohol and cannabis. AII were _26_ and short-lived. Not until 1846 did _27_ discover the anesthetic properties of ether, first in animals and then in _28_. Soon afterward, the usefulness of chloroform and nitrous oxide became _29_ and heralded a new era in surgery.
The dozen of _30_ used today during surgery abolish pain, _31_ muscles and induce unconsciousness. Other agents _32_ these effects after an operation.
Local anesthesia is used in a _33_ area of a person's body to prevent pain during examinations, _34_ procedures, treatments and surgical operations. The most _35_ of these agents, which temporarily interrupt the action of pain-carrying nerve _36_, is novocaine. Until recently, novocaíne was used as a _37_ anesthetic by dentists but lidocaine is more _38_ today.