Dear Doctor: I read that scientists are close to being able to "turn off" inflammation. What does that mean? And isn't that dangerous, since inflammation is a natural part of the immune system?

Dear Reader: The body's inflammation reaction is a double-edged sword. Most of the time we're grateful for the array of specialized white blood cells that rally to our defense. First to the scene of injury, illness and infection, they're specialists in detecting bacteria, viruses and other harmful organisms. They not only emit chemicals that destroy harmful invaders, they also cart away debris and rally the rest of the immune system to mount a robust response.

That's all great when things are working properly. But sometimes the body's inflammation response goes haywire. The same white blood cells that race to the rescue can be triggered by a case of mistaken identity and attack the body's own tissues. That's what's happening in autoimmune diseases like lupus, Crohn's disease or rheumatoid arthritis.

Certain conditions, like obesity, can rev up the inflammation process as well. That's because fat cells produce a class of small proteins known as cytokines, which are the same biochemicals that our white blood cells produce when they're on the attack. Those cytokines act as a 911 call to a host of other immune system cells, and thus encourage a state of ongoing inflammation. In addition to the autoimmune disorders we mentioned earlier, chronic inflammation has been linked to heart disease and certain cancers. And studies suggest that inflammation may have a hand in some diseases of the central nervous system as well.

All of which brings us back to the recent research that (we suspect) prompted your question. Among the cells that get involved in that initial immune response are white blood cells known as macrophages, which circulate throughout the tissues of the body. Now, a team of scientists from the United States, Ireland and the United Kingdom has identified a metabolic process that's able to get macrophages to stand down.

It turns out that a molecule known as itaconate, which is derived from glucose, acts as an "off" switch for macrophages. In a study published recently in the journal Nature, the researchers reported that the macrophages themselves can be instructed to make itaconate from glucose molecules. The presence of itaconate blocks the cascade of biochemical processes that add up to inflammation.

Specifically, a derivative of itaconate that can move in and out of the walls of our cells can actually decrease the production of cytokines, those small signaling proteins we were talking about earlier. The ability to control how macrophages produce and disperse cytokines would mean that certain types of inflammation could be controlled, or even stopped. The fact that it appears cytokines play a role in pain adds another intriguing layer of possibility to this discovery.

But before we celebrate the end of random inflammation, it's important to understand that at this point, the research has focused on mouse and human cells. The leap between the petri dish and the release of a targeted medication to control inflammation is a huge one.

(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: About 15 years ago, while giving blood, I was advised of an irregularity, which my doctor confirmed after an EKG, known as premature ventricular contractions. He told me not to worry, and I've not had any problems. Now I'm 79 and still in good health, but my current doctor had me wear a heart monitor and has now referred me to a cardiologist. Should I be concerned?

Dear Reader: Premature ventricular contractions (PVCs) are very common. In healthy people without any evidence of heart disease, 50-54 percent will be found to have some degree of PVCs when monitored for 24 hours. Here are the basics: Electrical impulses normally begin in the atria of the heart before they make their way down to the ventricles. This leads to the atria contracting first, followed by the ventricles. However, PVCs are ventricular contractions that bypass the atrial beat, leading to an extra heartbeat.

PVCs are more common in men than in women, increase in frequency with age and are more common in African-Americans. Lastly, they are more common in people with structural heart disease, especially those with congestive heart failure and those who have had heart attacks.

Most PVCs are not felt. It sounds as if you weren't having symptoms from the PVCs, but rather that they were simply noted on examination by your doctor. When patients feel PVCs, they often describe a sensation of a pause or a skipped beat. People also sometimes feel that the heart is beating hard or fast or that they have a strong pulsation in the neck. Sometimes PVCs can cause lightheadedness and anxiety. Very frequent PVCs have been associated with heart failure.

Sometimes, concerns about PVCs are related to their frequency, especially if they were sporadic and then become more numerous. Increased frequency of PVCs has been associated with an increase in mortality. This was illustrated in a 2006 study of 15,070 patients ages 45 to 64 who had no history of heart disease and who had a two-minute electrocardiogram performed. Those with one or more PVCs on the electrocardiogram had twice the likelihood of dying of coronary heart disease.

Similarly, a 2007 study of 45,402 veterans showed that 3.8 percent of the veterans studied had PVCs on a routine electrocardiogram -- and that the PVCs were associated with a nearly twofold increase in mortality. Note that routine electrocardiograms only last for 10 seconds, so detecting a PVC on an electrocardiogram suggests a very high frequency over a 24-hour period.

Studies over a 24-hour period have also shown that more frequent PVCs -- recorded in this way -- are also linked to an increased risk of heart failure and heart-related deaths, but the risk is greater when a PVC is seen on a routine electrocardiogram.

The heart monitor that your doctor recommended should pick up the number of PVCs over a 24-hour period. If the PVCs are frequent, the cardiologist may want to do other studies, like an echocardiogram, to determine whether there is any structural damage to the heart.

Treatment of PVCs for people with symptoms include calcium channel blockers and beta blockers. If these don't help control symptoms or if there is structural heart disease, anti-arrhythmic medication or electrical destruction of the area of heart that is causing PVCs may be necessary.

I would have some degree of concern regarding PVCs, but the results of the 24-hour monitor and your visit to the cardiologist will provide more 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: Are mumps really dangerous? Thousands of people apparently may have been exposed at a cheerleading event a few months ago, which seemed to upset public health officials. My kids have been vaccinated, but I'm not sure if I have been, or even if I've had the disease. Should I be concerned?

Dear Reader: Mumps is a viral infection that affects the parotid glands, which are one of three sets of salivary glands. The virus spreads when tiny airborne droplets of saliva are released during a cough, a sneeze and even through speech. These droplets, which contain the active virus, can then be inhaled by anyone in the infected person's vicinity. The virus can also linger on hard surfaces that those aerosolized droplets have landed on, so touching an object in an infected person's room, or sharing a sick person's food, glassware, dishes or cutlery can put anyone without immunity at risk.

In the incident you mentioned, tens of thousands of people were exposed to mumps when they attended the National Cheerleaders Association All-Star National Championship, which was held in Dallas. An attendee from outside the state turned out to be sick with mumps and was in the contagious stage of the illness. Someone with mumps is capable of spreading the virus anywhere from a few days before and up to five days after the onset of parotitis, which is the characteristic facial swelling that often accompanies the illness. The first symptoms of mumps typically appear 16 to 18 days after infection, though it can be as soon as 12 days, or as many as 25 days.

Mumps is not considered to be dangerous in the majority of cases. But as with any viral illness, it does take a toll on the body. In addition to the swelling of the salivary glands, symptoms can include fever, headache, muscle aches, tiredness, general malaise and loss of appetite. Up to 40 percent of infected individuals will have few or no symptoms. About one-third of males with the mumps who are post-puberty will also experience pain or swelling of the testicles. Complications, which are thankfully rare, can include deafness, infertility, meningitis and encephalitis.

There is no targeted cure for mumps at this time, so treatment consists of addressing specific symptoms. In most people, the disease will run its course in two to three weeks. The best form of protection against mumps is the MMR vaccine, which targets measles and rubella as well as mumps. The Centers for Disease Control and Prevention recommends children get two doses of the MMR vaccine, first at 12 to 15 months of age, and again at 4 to 6 years of age. And because immunity appears to wane over time, some epidemiologists now recommend a third dose of the vaccine for individuals living near a mumps outbreak. You can track current mumps outbreaks at cdc.gov/mumps/outbreaks.html.

Since you don't know your immunity status, we recommend that you contact your primary care physician, who can check your immunity through bloodwork.

(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.)