Undated (AP) _ Here is a summary of medical developments reported Wednesday:

SMOKING:

Smokers who cut back on doctors' orders may compensate by smoking more intensely, tripling the tar and nicotine they inhale, a study has found.

A co-author of the study, directed by Dr. Neal L. Benowitz of San Francisco General Hospital Medical Center, said, ''The best thing to do is quit entirely.'' But if cutting back, smokers should avoid puffing more deeply, more often or smoking each cigarette down to the butt.

The study was reported in Thursday's New England Journal of Medicine.

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SEAFOOD DANGERS:

A nutrition group, saying there was ''a public health scandal in the making,'' requested an improved federal inspection program for seafood.

By eating more fish because it is a healthy source of protein, Americans are at increased risk from bacterial, viral and toxic contamination, said a study released by Public Voice for Food and Health Policy, a non-profit advocacy group in Washington.

Spokesmen for the fisheries industry agreed on the value of inspection, but called the warnings overblown.

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FITNESS, HEART ATTACK DEATHS:

Keeping physically fit not only lowers the risk of heart disease but also helps prevent deaths from heart attacks, a study shows.

Men who are not physically fit are more than four times as likely to die of a heart attack as men who are fit, says the study reported at the annual meeting of the American Heart Association by Dr. Lars Ekelund of Duke University Medical Center.

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SEX HORMONES, HEART DISEASE:

Teen-age boys with elevated levels of estrogen and another sex hormone may be at increased risk for heart disease later in life.

The findings may be useful in predicting which boys will have heart disease, allowing preventive measures, John Morrison, an epidemiologist at the University of Cincinnati, said at the American Heart Association meeting.

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CHILDLESS WOMEN:

Childless women over 50 are more likely than mothers to have fatal heart attacks, according to a University of Pittsburgh researcher.

A study of medical records of women who died of heart attacks in Allegheny County, Pa., found that 12 of 51 heart attack victims were childless. In a group of 47 similar women who did not die of heart attacks, only two were childless, Evelyn Talbott told the American Heart Association meeting.

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SNORING:

People who snore have narrower throats than those who sleep quietly, and doctors say this may be one of the causes of their nightly rumbles and snorts.

The report in Thursday's New England Journal of Medicine said the snorers have abnormalities of the pharynx compared with others of the same age, weight and sex.

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PNEUMONIA VACCINE:

Pneumonia vaccine fails to protect older people from lung infections if they already are seriously ill with chronic diseases, a study has found.

The vaccine is often recommended for such people, who are at high risk of penumonia and who could die from its complications.

The study was directed by Dr. Michael S. Simberkoff of the Veterans Administration Medical Center in New York and published in the New England Journal of Medicine.