A look at stem cells and their current use

Dear Dr. Donohue Since starting to clip your articles, I haven't found any that deal with using adult stem cells for breakthrough treatments, such as repairing heart damage. Could they help if one needs an aortic valve replacement? A.R.

Answer Stem cells are primitive cells that have the potential of spawning mature cells that carry out specific bodily functions, like skin cells, liver cells, lung cells, heart muscle cells, and on and on. Embryonic stem cells have the greatest potential for differentiating into any of the many varieties of cells that make up all body organs, structures and tissues.

Hematopoietic stem cells are recovered from the bone marrow and, to a lesser extent, the circulating blood. They have been and are being used to restore the bone marrow's capability of generating blood cells.

At the present time, no stem cell therapy has been used in replacing a heart valve.

Dear Dr. Donohue I would like to know the risk of having a stroke when a carotid artery has a blockage. I was told that doctors don't go by percentage of blockage now. How is the risk determined? K.C.

Answer An obstruction in the carotid artery, the neck artery that supplies the brain with blood, is not the only cause of a stroke. A piece of a blood clot that has broken off of a main clot elsewhere in the body and been swept into a brain artery is another cause of stroke. I mention this to keep it clear that a blocked carotid is but one risk for a stroke.

The doctors I know still use percentage of reduction in the interior of a carotid artery as a criterion of stroke risk. With a 60 percent to 70 percent or greater narrowing of the carotid artery, people benefit from the opening up of the artery, using a variety of procedures. Some experts feel that a 60 percent narrowing requires only blood-thinning medication, such as aspirin. Others feel that surgical removal of the blockage is indicated.

Other factors have to be considered: the patient's age, the patient's wishes and the patient's health problems unrelated to the artery problem..

Dear Dr. Donohue I am an 85-year-old female, and my doctor has suggested a colonoscopy. I find it a degrading test. The doctor didn't say why I needed it. Should a woman my age have it? K.C.

Answer The American College of Physicians recommends against screening colonoscopies for people 75 and older or for those people with a life expectancy of less than 10 years. Some add that screening can be stopped only if prior colonoscopies have been normal. No one I know recommends screening at 85.

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A look at stem cells and their current use