Dear Doctor: Could you tell me about the causes, treatment and remission rates for Burkitt lymphoma?

Dear Reader: Burkitt lymphoma is a highly aggressive, rapidly growing type of B cell lymphoma. It's caused by an alteration to a gene involved with cell division and cell death. The alteration of this gene causes B cell lymphocytes (a type of white blood cell) to divide quickly and repeatedly, creating multiple abnormal cells.

There are three types of Burkitt lymphoma, and the likelihood of each one depends on your geographic region and your immune status. In Africa, the incidence of Burkitt lymphoma is 50 times higher than in the United States, with the disease there caused largely by chronic Epstein-Barr virus infection. In this type of Burkitt lymphoma, the peak incidence of infection is between the ages of 4 and 7. Often, the disease is initially found in the bones of the face or jaw; from there it can spread to other parts of the body.

The most common type of Burkitt lymphoma in the United States is much rarer -- about three cases per million people per year -- and the peak incidence is about 11 years of age, with the majority of cases occurring in people younger than 35.

The third type of Burkitt lymphoma occurs in people with a suppressed immune system, usually due to HIV infection. In these cases, the suppression of the immune system causes viruses, like Epstein-Barr, to exert genetic changes on B cells that lead to lymphoma.

Because Burkitt lymphoma is a rapidly growing cancer, chemotherapy works well against it, and multiple drugs are available to stop its growth and destroy the rapidly growing B cells. In fact, because drugs are so effective, radiation and surgery are not generally recommended. Of note, many chemotherapy regimens now include the medication Rituxan, often used for rheumatoid arthritis, because of its ability to attack B lymphocytes. Because Burkitt lymphoma can often make its way to the brain, most chemotherapy treatments are also given via the cerebrospinal fluid by way of a lumbar puncture.

Chemotherapy is not without its side effects. Part of the difficulty in older adults, especially those over the age of 60, is the ability to tolerate these side effects. They include bone marrow suppression, in which the numbers of red and white blood cells and platelets drop dramatically. The drop in the white blood cells can make a patient more susceptible to severe bacterial infections. Chemotherapy can also lead to toxicity of the heart and the nerves of the body.

As for survival rates, those depend on the regimen of chemotherapy and the age of the patient. A study from Germany found that people ages 15 to 25 had a five-year survival rate of 90 percent; the rate decreased to 84 percent in people ages 26 to 55, and to 62 percent in those over 55.

You didn't say whether you or someone you know is being treated for Burkitt lymphoma, but, if so, I hope this limited review has been helpful.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My 81-year-old father is scheduled for a heart procedure, and I'm actually less worried about the surgery itself than the effects of the anesthesia. I've read that it can lead to memory loss in the elderly. Is there any way to help him?

Dear Reader: The condition you're referring to is known as postoperative cognitive dysfunction, sometimes shortened to POCD. It's loosely defined as impairment to the mental functions of an individual following surgery performed under general anesthesia. And while your question zeroes in on anesthesia as the cause of those cognitive side effects, the jury is still out on that. Some researchers point to the rigors of surgery itself as well as the body's resulting inflammation response as contributing factors to the condition.

Symptoms of POCD include impaired memory, difficulty learning and retaining new information, a shortened attention span, problems carrying out more than one task at once and a decline in the ability to concentrate. These can develop over time following surgery and may last a few weeks, a few months or in some cases become permanent. While the condition can occur in any surgical patient, it's most often seen in elderly individuals.

One of the challenges to diagnosing POCD is that unless the patient has undergone pre-operative cognitive testing, assessing his or her post-operative condition relies on observational and anecdotal evidence. In cases where the syndrome is pronounced, a reliable diagnosis can be made. But in more subtle cases, where those around the patient feel he or she has "lost a step" following surgery, citing POCD as the direct cause becomes more difficult. With that in mind, we'd like to share with you the following recommendations from the American Society of Anesthesiologists:

-- Before surgery, undergo a cognitive test that can be used as a baseline against which to compare similar post-surgical testing, if needed.

-- Make sure your surgeon is familiar with all medications and supplements you're taking in the weeks and days before surgery, and any that you plan to take following the procedure. This includes medications to address pain, sleep and anxiety.

-- Patients who wear glasses or use hearing aids find it easier to re-enter the post-surgical world when their sight and hearing are at optimal levels. Assign someone the task of making them available to you as soon as possible following surgery.

-- Arrange for a caregiver, who can notice and report any troubling symptoms, to visit with you regularly as you recover.

-- Anchoring yourself in the present as soon as possible after surgery is important. Request a room with a window, so you have visual cues regarding the passage of time, as well as your physical location.

-- In that same vein, photos of family, friends and pets, familiar possessions, and a clock and a calendar, all can help you readjust.

With an aging populace, many of whom will go on to require surgery, recognizing and preventing POCD is rapidly becoming a public health issue. A wide range of researchers are now focused on it. As new findings emerge, we will share the latest information.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: What can you tell me about an allergy to nickel? I recently had skin testing after experiencing itchy skin, a rash and fluid-filled blisters that several doctors thought might be mosquito-related. Instead, I tested positive for nickel allergy. Even the nickel in my bra clasps and earrings make me break out. Do I need to avoid certain foods? Is this problem hereditary?

Dear Reader: Nickel allergies are quite common. Although nickel is only about .009 percent of the Earth's crust, the metal and its compounds are found in a large number of common objects, such as coins, earrings, rings, watches, bras, belt buckles, mobile phones, medical devices and dental implants. And, as you referenced, nickel is found in small amounts in many foods. Unfortunately, nickel is the most common metal allergy in humans, affecting more than 10 percent of people in the United States. Women are five times more likely to have an allergic reaction to nickel than are men, largely because of their exposure to nickel-containing jewelry.

For people with nickel allergies, nickel ions provoke an immune response within the skin. After multiple exposures, the immune system can overreact when exposed to the metal. This type of reaction is called a delayed hypersensitivity reaction and it occurs 48 to 72 hours after the exposure.

There does appear to be some genetic predisposition to nickel allergies, but really, allergies to nickel are more related to exposure than to heredity. People who frequently handle coins, such as cashiers and toll road collectors, have greater amounts of allergic reactions on the hand than does the general population.

Again, the problem with nickel is how commonly the metal is used in clothing and in jewelry. That can be attributed to its strength and its resistance to oxidation. That said, Denmark has regulated nickel in its consumer goods and thus has the lowest rates of nickel allergy among industrialized countries. Other European countries have taken similar action; the United States has not.

Obviously, the best course of action is to avoid nickel in clothing and jewelry. One way to detect nickel is through a rapid testing kit, or dimethylglyoxime test. Here's how it works: You apply the test solution to a cotton swab, rub the swab on the metal of a product you're thinking of buying and -- if the product contains any nickel -- the swab turns pink.

Titanium, platinum, sterling silver, some types of stainless steel and gold that is at least 18 karats should be free from nickel. As for earrings with nickel (a common metal in such jewelry), you can create a barrier between it and your skin by coating the metal that touches your ear with nail polish or specific products marketed for nickel allergies. For clothing with nickel-containing buttons, you can apply an iron-on cloth over the metal portion or simply use duct tape. Finally, you can use barrier creams on the skin that comes in contact with nickel from jewelry.

Case reports suggest that skin reactions to nickel can diminish with a reduction of nickel in the diet, but your reaction appears to be related specifically to skin contact. So, for you, if you can't avoid nickel, I recommend using a barrier against it.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)