Health & Science

The death-by-smoking gene

Why can some people quit smoking overnight, while others keep relapsing for years? Why do some long-term smokers live to 100, while others are felled by lung cancer in their 40s? The answer, say three new studies, lies in the genes. Scientists who scanned the DNA codes of more than 35,000 people have found a set of mutations that seem to make smoking more addictive and to increase the risk of lung cancer. “This is kind of a double-whammy gene,” says study author Christopher Amos. Of all people who smoke, about 14 percent eventually develop lung cancer. Inheriting the smokers’ gene from one parent seems to increase that risk by more than 30 percent. The unlucky smoker who inherits the deadly gene from both parents is 80 percent more likely to get cancer. This same smoker, researchers found, will smoke more cigarettes per day and find it much harder to quit. These findings suggest a biological underpinning to addiction that varies in strength from person to person, and may explain why some addicts find their substance of choice so compelling, says Dr. Nora Volkow. “It opens our eyes,” she tells The New York Times. “Not everyone takes drugs for the same reasons. Not everyone smokes cigarettes for the same reasons.”

Longer isn’t better

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Contrary to myth, the best sex doesn’t last all night long, says a new survey of sex therapists. In fact, the optimal time spent on intercourse is about the same as the time it takes to microwave a frozen burrito. Good sex (not counting foreplay) should last more than three minutes, the therapists said, but less than 13—any more time and the experience starts to get tiresome. The sex therapists surveyed, who based their answers on real-world experiences reported by hundreds of couples, said many men suffer from the misconception that only a marathon man can satisfy his partner. Previous research, involving 1,500 couples, showed that the average length of intercourse is actually seven minutes. “There are so many myths in our culture of what other people are doing sexually,” says Marianne Brandon, a clinical psychologist and sex therapist. “Most people’s sex lives are not as exciting as other people think they are.”

The first man-cow

British researchers have blurred the lines between animal and man, creating an embryo that is part human, part cow. The announcement of the first human-animal hybrid by embryonic researchers at Newcastle University has ignited enormous controversy. The scientific feat was called “a monstrous attack on human rights, human dignity, and human life” by Roman Catholic Cardinal Keith O’Brien of Scotland. The researchers created the hybrid by injecting human DNA into eggs harvested from cows. Though most of the cow’s genetic material had been stripped away, some remained, so that the embryo was indeed a human-animal hybrid. Scientists used cow eggs simply because they’re far easier to obtain, and said that this technique would be useful for basic research on stem cells and other embryonic studies. Under British law, hybrid embryos have to be destroyed after 14 days.

How fasting can fight cancer

A new technique minimizes the nausea and other side effects of chemotherapy at the same time that it kills more cancer cells. Curiously, the method isn’t a drug or a therapy but an extremely restrictive diet: Patients are told to starve themselves for two days before every dose of the toxic chemotherapy drugs. So far, the treatment has only been used on mice, but it was extremely effective. Cancer-stricken mice that were starved before chemo survived longer and suffered far less than the mice that were given the standard treatment. When normal cells are starved, they go into a defensive mode in which they stop growing and replicating and use all their energy to fend off and repair damage. Cancer cells, on the other hand, keep growing and copying themselves no matter what, leaving them vulnerable to attack. So when a fasting person receives chemotherapy, most of the healthy cells aren’t affected by the powerful toxic drugs, while the cancer cells are. Standard chemotherapy treatment ends up affecting normal and tumor cells equally—that’s why people in chemo get so sick. Researcher Valter Longo hopes to start human trials within months. “Within a year,” he tells Agence France-Presse, “you could have this into many different hospitals.”

A cure for cirrhosis?

Japanese researchers have invented a technique that can erase a lifetime of liver damage. Cirrhosis of the liver, a potentially fatal condition brought on by years of alcohol abuse or hepatitis, occurs when collagen-filled scar tissue replaces the normal cells of the liver. When cirrhosis takes over much of the organ, the liver can’t perform its vital functions, and the cirrhosis patient’s only hope is a transplant. But researchers at the Sapporo Medical University in Japan have found a way to completely reverse the disease in rats. When they injected diseased rats with a drug that blocks collagen production by liver cells, “we cured them of the cirrhosis,” researcher Yoshiro Niitsu tells Scientific American. “After you remove the fibrosis, the liver by itself starts to regenerate tissues. So liver damage is reversible.”