DEAR DR. DONOHUE: My mother, 92 years old, suffered a stroke, and she is not able to speak. Her current problem is a bedsore, which, they tell me, is quite deep. She is in a good nursing home, but they are understaffed. Could we get her a special mattress or bed? Would that help? – S.M.

ANSWER: Bedsores have another, more appropriate name – pressure ulcers. They arise when the skin and surface tissues are pressed between two unyielding surfaces – a bone and a firm mattress. The three most common sites for them are the lower back, the side of the hip and the heel.

Pressure on the skin and underlying tissues stops blood flow. If blood does not continuously flow to and nourish tissues, they die. That, in a capsule, is a pressure ulcer.

In addition to pressure, moisture favors bedsore formation. I imagine that your mother is incontinent. Lying in a pool of sweat, water or urine turns skin cells into mush that breaks apart. Friction that comes when a body slips downward (or upward) against a sheet also tears off the outer layer of skin.

There are special beds and special mattresses that can alleviate the pressure that is bound to develop between bones and a mattress. One is an air-fluid bed. It’s a bed whose mattress contains silicone-coated beads. The bed comes with a gadget that pumps air into the mattress. The air liquefies the beads, and pressure between bones and mattress is greatly reduced. The bed automatically adjusts airflow so patients are protected no matter how they roll around in the bed.

Pressure-sore-preventing mattresses are also available. There are a number of them. Talk with the nursing home supervisor, and she or he can guide you to one most suited to your mother’s needs.

For her present sore, meticulous care must be given to the sore if it is ever going to heal. All dead tissue in the sore must be removed. Why not get a surgeon’s opinion on how best to get the bedsore clean and dry?

DEAR DR. DONOHUE: It seems I cannot turn on the television without hearing some mention made of beta carotene. What exactly is it? What does it do? – C.M.

ANSWER: The body can turn beta carotene into vitamin A if its supply of that vitamin is low. In its own right, beta carotene is an antioxidant. From the myriad of chemical processes body cells perform, noxious waste materials – oxidants – are produced. If oxidants are not neutralized, as they usually are, they cause destruction to cells and tissues.

For many years, the spotlight shone brightly on beta carotene. Beta carotene fans claimed it would stop artery hardening, bone loss, and cells from becoming cancerous. The spotlight has dimmed considerably. An excess appears as dangerous as a deficit. Smokers, for example, who supplement their diet with beta carotene have a greater risk of developing lung cancer.

People can get all the beta carotene they need from fruits and vegetables. If you take a daily multivitamin, check to see if it has beta carotene. If it has less than 15,000 IU, there is no problem.

DEAR DR. DONOHUE: As I have gotten older, I have noticed that my testicles are bigger. I am 80. They don’t hurt or cause me any problem, but I would like to know the significance of this. Is it something that happens with aging? – A.S.

ANSWER: Testicle enlargement is not a normal consequence of aging. Whenever testicular enlargement occurs, everyone thinks of cancer. Testicular cancer, however, is more common in younger men – men in their 30s. It can occur at any age, but it is less likely to occur in 80-year-old men.

A more likely explanation is a hydrocele or varicocele. A hydrocele is a collection of fluid in the space between the two-layered testicular coverings. It usually is harmless and can be left alone if it’s not causing trouble. Varicoceles are dilated testicular blood vessels. They, too, can be ignored if not causing trouble.

I have stuck my neck out, and I don’t like it there. You must see a doctor for a one-on-one examination.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475.