Wednesday, August 23, 2006

Nicotine Receptors Studied

Smoking may rewire people's brains in a way that makes it difficult to quit, a study says.

Smokers who stopped for seven days still had a much higher number of nicotine receptors in their brain than nonsmokers, a surprising finding to researchers who said that past studies in animals had shown a much quicker drop-off in the receptors.

The study suggests that many smokers may need stronger doses of nicotine in replacement patches, gums and sprays to "keep all the nicotine receptors occupied in the short term before weaning off to lower doses," said Julie Staley, a Yale University School of Medicine psychiatrist who led the study.

"There's evidence that replacement therapy only works for some people, maybe about half of those who try it," Staley said in an interview.

The research will be published today in the Journal of Neuroscience.

Brain scans of 16 smokers who gave up cigarettes for four to nine days showed nicotine receptor levels that were 26 to 36 percent higher than brains scans of 16 nonsmokers of similar age and sex, the study said.

Bausch & Lomb Inc.'s global recall of a popular contact lens solution in May appears to have stopped the spread of a serious eye infection, but scientists still do not know what caused the outbreak, the Centers for Disease Control and Prevention said yesterday.

They found no infection in the Bausch & Lomb solution itself but do not believe improper lens hygiene practices by consumers alone explain the outbreak of the fusarium keratitis infection, which in some cases required a cornea transplant.

"We feel pretty confident that the outbreak is over," said CDC researcher Benjamin Park, who has studied the outbreak since the first reports of the infection in the United States in early March.

The rare but potentially blinding eye infection prompted Bausch & Lomb to halt shipments of its ReNu with MoistureLoc lens solution to U.S. retailers in April.

According to the study in the Journal of the American Medical Association, infected contact lens wearers were 20 times as likely to have used Bausch & Lomb's ReNu with MoistureLoc lens solution as other solutions.

A new study finds an encouraging decline in infections with genital herpes virus.

The new study shows a 19 percent drop since 1994 in the percentage of Americans ages 14 to 49 testing positive for herpes Type 2, the most common cause of the recurring painful sores of genital herpes. The declines were especially pronounced among young people.

The findings, in today's Journal of the American Medical Association, represent biological evidence of a decrease in risky sexual behavior by adolescents, said lead author Fujie Xu of the Centers for Disease Control and Prevention.

But herpes is still widespread. Blood tests of more than 11,000 people found that 11 percent of men and 23 percent of women carry the genital herpes virus. Among people in their twenties, the infection rate was almost 11 percent.

"It's still an epidemic," said Tom Cherpes of the University of Pittsburgh School of Medicine. "The fact that there's a trend downward should not be construed by anybody that herpes is under control."

-- From News Services