The spare tire you stow around your waist might someday replace your creaky knee. According to a study published in Tissue Engineering, stem cells from human fat can be turned into muscle, bone or cartilage. Fat, marrow and bone all develop from the mesoderm layer of embryonic tissue in humans. Using tissue from a patient's own stem cells would eliminate the risk of rejection and exposure to viruses from a donor.

However the heel is stacked, it is bad for you. Most women, knowing that stick-thin high heels can cause foot problems, opt for their chunkier cousins. While this may save their feet, a study published in The Lancet shows that chunky-heeled shoes can cause knee problems instead. Also, the more “sensible” chunky heel comes with a false sense of comfort and safety that encourages women to wear them longer, which also threatens the knees.

Exercisers have always been told, “no pain, no gain.” However, according to two new studies, even a little pain can lead to noticeable improvement. Results of a Dutch study published in Nature show that any extra activity, such as taking the stairs rather than the elevator, can help people shed pounds. In addition, a study published in JAMA shows that women who walk even one hour a week reduce their risk of heart disease by one half.

Are you worried that your household cat might trigger asthma in your children? Don't be too quick to toss Fluffy out of the house. According to study results recently published in The Lancet, household cat allergens can actually decrease the risk of asthma. Researchers believe that high levels of exposure to allergens alter the immune response to cats over a period of time.

Don't be too quick to throw out Fido either. Thanks to the K9 Top Coat, a Lycra bodysuit for dogs, dog owners no longer must have their homes covered with dog hair. Available from an Oregon-based company, the lightweight “coat” covers 90 percent of the dog's body and comes in five colors. The coat not only stops shedding, but also keeps the dog's fur clean, prevents the dog from licking and biting at healing wounds, and keeps burrs, stickers and ticks at bay.

Stuttering has been believed to be caused by nervousness and stress. While these conditions do aggravate stuttering, new positron emission tomography imaging study results, as reported at a recent American Speech-Language-Hearing Association national meeting, reveal that stutterers use the opposite side of their brain when speaking. Scans of nonstutterers' brains show that both hemispheres light up when they speak, but with more activity on the left side. To the contrary, scans of stutterers' brains show more activity on the right side of the brain. Researchers also found that stutterers are deficient in a region of the brain that processes hearing when speaking.

When considering the likelihood of birth defects, the mother's age is usually considered a major factor. However, according to a study published in the Archives of General Psychiatry, the risk of having a child with schizophrenia increases with the father's advancing age. Researchers found that men between the ages of 45 and 49 are twice as likely to have a child with schizophrenia as men younger than 25. Some cases of schizophrenia might be a result of genetic sperm cell abnormalities that become more common as a man ages.

Pneumonia-related deaths in severely burned patients may be reduced by selective decontamination of the digestive tract. Pneumonia occurs in 65 percent of burn patients who require mechanical ventilation, according to a study published in Chest. Over a two-year period, 56 burn patients were studied for types of pneumonia and the interventions used for each. More than one half of the burn patients requiring ventilation developed pneumonia. This rate was two times higher in patients with inhalation injury than in patients without such injury.

Researchers aren't monkeying around when they say that more attention should be given to estrogen levels during pregnancy. While studying the estrogen levels of pregnant baboons, a team of researchers at the University of Maryland School of Medicine and Eastern Virginia Medical School found that the female offspring of baboons with low estrogen levels were born with underdeveloped ovaries and produced about one half the normal number of eggs. They also had a higher number of abnormal and broken eggs.

A study published in JAMA set out to settle a dispute over whether statin use reduces age-related fractures. Considering many variables, patients with fractures and a history of statin use were compared with age-and sex-matched control patients. Researchers found no relationship between statin use and reduction of fracture risk. Patients using nonstatin lipid lowering drugs also had fracture risks comparable to patients with untreated hypercholesterolemia.

Many high-level executives wanting to return quickly to their office responsibilities are opting for off-pump coronary artery bypass surgery, according to surgeons at Yale School of Medicine. By allowing the heart to keep beating during surgery, this method eliminates the “pump-head” syndrome that commonly occurs when the heart's functions are artificially replaced with a heart-lung machine. Pump-head syndrome is characterized by insomnia, depression, short-term memory loss, and difficulty reading and concentrating. It often occurs in persons with demanding careers or otherwise high-stress lives.

Why didn't the sperm fertilize the egg? Because it wouldn't ask for directions. More molecularly correct: it's because the egg keeps changing the lines to its prized yolk. A study published in the Proceedings of the National Academy of Sciences shows that three reproductive proteins in the mammalian egg are among the most rapidly evolving molecules in the body. It had been previously assumed that the egg was stable, and the focus had been on the male component's habit of changing and adapting under selective pressure.

“Home, smart home.” Through the growing power of computer networks and sensors, aging adults might soon be able to remain in their homes (and out of nursing homes) for much longer. Using sensors that track sound and vibration, the “home” would monitor the occupants' health, alerting friends and family of changes. Unobtrusive “aids” would provide help for memory lapses and remind the occupants to take their medications and to eat and drink.

We all know people who can't pass up sugar, and others who can easily walk away from it. Two studies published in Nature Genetics show that a “craving sweets” gene may exist. The theoretic T1R3 gene has yet to be proved as the cause for sweets-eating. However, scientists are hopeful that research could lead to new developments in the field of sugar, that diabetics and people watching their weight could someday switch the gene to “off,” and that artificial sweeteners could become tastier.