CHECKUP : NEWS, TIPS AND TRENDS FRESH OUT OF THE OVEN: THE SWEET SMELL OF EXCESS?

Some people contend that they can gain weight just by smelling a freshly baked chocolate cake, and now a new study suggests there might just be something to that.

Purdue University food scientists found that just tasting fatty foods, but not swallowing them, may elevate levels of fatty substance in the blood. The test involved 15 people, some of whom tasted cream cheese on crackers, some had fat-free spread and some had plain crackers. All were instructed to spit out the food after chewing it for a while to taste it.

Why those who had tasted cream cheese showed a change in blood fat measurements while the others didn't is a mystery to the researchers. ``It seems that some chemical feature of the fat may provide the cue for the effect,'' said Richard Mattes of Purdue. ``But what that feature is and what level of fat is required will be issues that have to be addressed in future studies.''

Perfect (pitch) genes: Geneticists at the annual meeting of the American Society of Human Genetics were singing about musical ability.

Two research groups reported studies on perfect pitch, the ability to name a musical note without comparing it with another note.

Scientists have known that perfect pitch runs in families, but a clear genetic basis hadn't been established, said Siamak Baharloo, a graduate student at the University of California, San Francisco.

Baharloo sent surveys to music schools across the country and found that musicians with perfect pitch were more likely to have someone else in their family who also had the ability. And since some musicians with years of musical training didn't have perfect pitch, Baharloo said he favored the theory that perfect pitch is largely in the genes.

Another study presented by researchers at Cornell University Medical College in Manhasset, N.Y., also suggested that perfect pitch has a genetic basis. Both groups are preparing to search for the gene or genes linked to the trait.

A successful gene hunt will give scientists a window into human perception, Baharloo said.

``This goes at the core of our nature: why we hear the same thing but perceive it differently,'' he said.

Transplanted tumor: In an unusual event, a surgeon has accidentally transplanted a patient's malignant tumor cells into his own body.

Last week, German physicians from Eberhard-Karls University in Tubingen described the case of a 53-year-old surgeon who nicked the palm of his hand during an operation. The patient, who was suffering from a tumor in his abdomen, eventually died.

Five months after the surgery, the doctor developed an inch-long tumor in the exact spot of his injury. It was the same type of cancer found in the patient. The surgeon's tumor was removed.

Suspecting a connection, the hospital pathologist ordered a genetic comparison of the two cancers.

``Using molecular methods, we showed that the sarcomas in the unrelated patient and surgeon were genetically identical,'' the researchers wrote last week in the New England Journal of Medicine. The accident occurred two years ago, and the surgeon remains well, they reported.

While this is not the first time tumor cells have been accidentally transplanted, it is rare for cancer to develop, the scientists say. Normally the immune system surrounds the malignancy. However, in this case the tumor appears to have escaped destruction by the body's defenses.

New label law: The Food and Drug Administration has announced new regulations that will change the way milk is labeled.

Two-percent milk can be labeled reduced-fat but not low-fat, according to the regulations, which go into effect on Jan. 1, 1998. Skim milk can be referred to as skim milk or as fat-free, no-fat, non-fat, free-of-fat or zero-fat.

The new changes are intended to make milk labeling more consumer friendly, according to the FDA. Although many people use lower-fat milk products to decrease their fat intake, 2-percent milk is not low in fat - as defined by other FDA standards, the FDA said.

Ebola's natural habitat?: The Ebola virus appears to grow readily in bats without causing disease, suggesting that the animals may be the virus's natural hiding place.

Since the virus first revealed itself in the late 1970s, scientists have searched for its source in nature. Despite exhausting investigations of jungle plants and animals, Ebola's lair between outbreaks remains a mystery.

Despite this finding, the scientists note, ``much remains to be learned about the nature of the infection in bats.''