Could you discuss the new approach to vaccines that could supposedly revolution immunization?

DEAR DOCTOR K: I heard on television about a possible new vaccine against HIV, Ebola and other terrible viruses. That sounds like very good news, or is it just hype?

DEAR READER: You may well have heard about a new approach to creating vaccines. The approach is called "passive immunization with neutralizing antibodies." It could revolutionize immunization against Ebola and other viruses, including HIV (the virus that causes AIDS) and influenza (flu) viruses.

Can I do anything to help prevent another kidney stone?

DEAR DOCTOR K: I recently passed a kidney stone, and it was really painful. My doctor gave me medicine. Is there anything else I can do to prevent another one?

DEAR READER: Besides the medicine, your diet can influence your risk of getting another kidney stone. Kidney stones are hard chemical deposits that form inside the kidneys. They can be as small as grains of sand and pass painlessly out of the body in urine. But they also can be the size of a pea, a marble or even larger.

What can elephants teach us about cancer?

DEAR DOCTOR K: I heard on the radio about a new research finding that elephants don't get cancer. If we could figure out why, could we protect ourselves against cancer?

DEAR READER: A recent study found that elephants (and many animals) do, in fact, get cancer, but have lower rates of death from it than humans do. The study also found one possible explanation that, as you suggest, might someday help us deal with cancer.

How can I practice mindful eating?

DEAR DOCTOR K: I've heard so much about mindful eating. How do I practice it?

DEAR READER: Mindful eating is the opposite of mindless eating -- a lack of awareness of the food we're consuming. What is mindless eating? Think about something you've eaten in the past few hours. You probably remember what it was -- say, an apple. But do you remember the sensation of eating it? The burst of juice as you bit through the skin? The initial tart bite, followed by the sweetness of the apple's flesh? If you're like many of us, then probably not.

Can children benefit from yoga?

DEAR DOCTOR K: My 8-year-old daughter has expressed an interest in taking a yoga class, but I don't want to waste my money. Can children really benefit from yoga?

DEAR READER: Yes, they can. I spoke to Dr. Marlynn Wei, who is a psychiatrist, certified yoga teacher, and author of the upcoming Harvard Medical School Guide to Yoga. She noted that yoga and mindfulness (a related practice) have been shown to improve both physical and mental health in children.

What is retinal vessel occlusion?

DEAR DOCTOR K: A friend recently lost vision in his right eye because of something called "retinal vessel occlusion." What is that? Can it be prevented?

DEAR READER: The retina is the light-sensitive layer at the back of the eye that receives light and then sends a signal to the brain -- resulting in vision. Most of the blood circulation to the retina comes through one artery and one vein. If either blood vessel or one of their smaller branches is blocked, this is called an occlusion.

What is the right way to dispose of unused medications?

DEAR DOCTOR K: I've heard that some people dump their unused medicines into the sink or toilet, which then gets into our drinking water. Is this true, and could it affect my health?

DEAR READER: Unfortunately, it's true. There is increasing concern about chemicals from unused medications making their way into our drinking water.

What makes berries so healthy?

DEAR DOCTOR K: You often list berries as one of the most nutritious foods. It's berry season, and my wife wants to buy lots of them, but they're a little expensive. So, I'd like to know what makes them so healthy. Call me a skeptic.

DEAR READER: I know, I know, I keep repeating it's the berries. But that's because it's true. And if the expense is an issue, consider the expensive foods you buy that are definitely unhealthy. I don't need to list them -- you know what they are.