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New insight into how primary lung cancer turns into invasive, or metastatic, cancer could lead to treatments that improve patient survival, U.S. scientists say.

The research team at the University of Texas M.D. Anderson Cancer Center found that lung cancer becomes invasive by suppressing a type of microRNA that normally keeps tumors in a non-metastatic state. Specifically, when microRNA-200 was suppressed in mice prone to metastatic lung cancer, all their primary lung tumors became invasive, the study found.

The study appears in the Sept. 15 issue of the journal Genes & Development.

“Existing treatments have little success against cancer that has spread to other organs, so finding a way to prevent metastasis could have a huge impact on survival,” senior author Dr. Jonathan Kurie, a professor in M.D. Anderson’s Department of Thoracic/Head and Neck Medical Oncology, said in a university news release.

“To do that, we need to understand the cues that initiate metastasis. In this paper, we show that microRNA-200 is one of those central cues,” he explained.

The researchers are now trying to identify regulators of microRNA-200 that might offer targets for treatment.

High exposure to certain now-banned industrial chemicals may lead to fewer female births, a new study suggests.

The findings, reported in the journal Environmental Health, add to evidence that the two groups of related chemicals — polybrominated biphenyls (PBBs) and polychlorinated biphenyls (PCBs) — may affect human reproduction.

PBBs were once widely used as flame retardants in plastics, electronic and textiles, while PCBs were used in everything from appliances and fluorescent lighting to insulation and insecticides.

While the chemicals were banned in the 1970s as potential health hazards, they remain a public-health concern because they linger in the environment and accumulate in the fat of fish, mammals and birds.

For the current study, researchers used data from a group of Michigan residents who, in the early 1970s, had been inadvertently exposed to high levels of PBBs; the chemicals had been accidentally mixed into animal feed, leading to human exposure through contaminated meat, eggs and milk.

The researchers observed that, from 1975 to 1988, women in the study group had a higher-than-average rate of male births, relative to the national average.

There was also a suggestion of increased odds of a male birth when both parents’ combined PBB exposure was particularly high — above the midpoint for the study group — compared with couples whose PBB exposure was lower.

Similarly, couples with high PCB levels had a higher rate of male births.

What this all means for the public at large, however, is unknown, according to lead researcher Metrecia Terrell, of Emory University in Atlanta.

“This was a unique situation, so it’s very difficult to extend the findings to people with everyday exposures,” she said in an interview.

“Exposure in the general population would be much lower,” Terrell pointed out, “and we just don’t know if there are effects on sex ratio.”

Male births have always outnumbered female ones, but some research suggests that the male-to-female birth ratio is declining in the U.S. and elsewhere. One recent study found that in the U.S. in 2001, there were 104.6 boys born for every 100 girls; that compared with a ratio of 105.5 male births for every 100 female ones in 1970.

The researchers speculate that environmental toxins might be playing a role. Certain chemicals may, for example, affect the viability of sperm that bear the Y chromosome — which determines male sex — or the viability of male fetuses.

In this study, however, high exposure to PBBs and PCBs was linked to an increase in male births. Exactly why is unclear, according to Terrell.

Certain PBBs and PCBs have been shown to alter levels of male and female sex hormones, she and her colleagues note. But whether they promote the survival of Y-bearing over X-bearing sperm, or affect the survival of female fetuses is unknown.

Terrell said that continuing research on the chemicals’ potential reproductive effects is needed.

New research has uncovered possible causes of epilepsy related to signals in the brain that go haywire.

It suggests that when a certain protein is missing in the brains of mice, the animals have epileptic seizures. The protein appears to be important to the brain’s ability to calm and fine-tune itself.

The researchers, who report their findings in the Sept. 18 issue of Cell, found that neural connections in the brain were excitable in the mice even though connections appeared normal.

When the protein was restored, the brains of the mice began acting normally again.

The specific protein referred to is one encoded by plasticity related gene-1 (PRG-1) and is found only in the brain, according to the researchers. Its calming effect depends on how the protein interacts with lipids that provide a signaling function in the brain.

Epilepsy occurs when signals in the brain become disrupted. People with the condition can suffer from a long list of symptoms, including seizures, strange behavior and emotions, and loss of consciousness.

There’s no cure for the disorder, but it can be controlled by medicine and surgery in an estimated 80 percent of cases. In recent years, people with epilepsy have turned to a device that stimulates the body’s vagus nerve.

With the H1N1 swine flu virus lurking in every nook and cranny, all Americans should be on guard this coming flu season.

But experts say those living and working in crowded locales — schools, colleges, prisons, cruise ships, airplanes, military barracks — need to be extra careful.

“Any crowded place carries a heightened risk,” said Dr. Melinda Moore, a senior health researcher at the Rand Corp., in Arlington, Va. “It really has to do with people being in close quarters and having disease-transmitting behaviors such as coughing and sneezing.”

“The virus is mainly spread the respiratory route, and it’s also on inanimate objects like doors and knobs and handles and desktops and telephones,” added Dr. Stuart Beeber, attending pediatrician at Northern Westchester Hospital Center, in Mount Kisco, N.Y. “It’s mainly in close quarters where a lot of people are together, such as in classrooms or offices, potentially even movie theaters.”

The danger of transmission lies not only in the fact that hordes of people are together for long periods of time, but that those hordes may not be practicing good hygiene.

“Any environment in which people are crowded together with compromised hygiene carries a heightened risk,” said Dr. Dean Blumberg, an associate professor of pediatric infectious diseases at the University of California, Davis, Children’s Hospital. “It’s when people don’t have access to hand washing or shower facilities.”

Younger children are not naturally very hygienic, Blumberg pointed out.

College students may also engage in behaviors that are friendly to the spread of the H1N1 virus, such as kissing and sharing drinks. If those drinks are alcoholic, judgment may be affected, resulting in even more unsafe behaviors. Smoking can also compromise the respiratory system, making you more vulnerable to infection, Blumberg said.

The added problem in jails and prisons is that stepped-up hygiene needs to be balanced with safety and, in some cases, could actually compromise safety, Blumberg said. For example, “alcohol-based hand gels can be dangerous in that environment,” he said.

Budget cuts may even be contributing to a hygiene crisis. The current fiscal problems plaguing California affect all school facilities, including those related to hygiene, Blumberg said.

“The people involved may not be quite as interested in disease prevention compliance as they are with other things, but that doesn’t make it any less important,” Moore said.

The first line of protection is what experts call “respiratory etiquette.” Coughing and sneezing into your elbow or handkerchief doesn’t require any special facilities. And, as often as you can, wash your hands or cleanse them with hand foam or alcohol gel. “You may also want to wipe down surfaces that you are in frequent contact with, like door knobs,” Beeber said.

These are also messages the airline and cruise-ship industry are emphasizing more than usual right now, although, for the most part, it’s business as usual for travelers.

According to Erik Elvejord, a spokesman for Holland America Line, based in Seattle, the cruise ship industry is already bound by strict public health standards, including not letting sick passengers board a ship and isolating sick passengers who are already on board. Ships do have some flu-testing equipment on board as well as antivirals, he said. Passengers also receive notes on their pillow reminding them to wash their hands, and containers of hand sanitizer are placed all around the ships, although these measures are not new, Elvejord added. “We’ve kind of been doing what we’ve been doing all along,” he said.

Although one passenger on a recent commercial airline flight was told by the flight crew that blankets were no longer available in economy class because of swine flu concerns, David Castelveter, a spokesman for the Air Transport Association (ATA), said he has “not seen that wholesale.”

For the most part, the airline industry is also proceeding with travel-as-usual. “We [already] have pretty sophisticated filtering systems,” he said.

Debunking one persistent myth, Castelveter stressed that cabin air is not recirculated, but comes in the side, moves in a circular motion, then exits the plane into the great beyond. The worst danger comes from the person sitting next to you — not in front or behind, Castelveter said. “The person who sneezes in row 3 will have no impact on someone sitting in row 11,” he said.

Airlines are being more diligent in passing out hand-washing messages, and both water and antibacterial soap are available on most airplanes.

The ATA is also communicating regularly with CDC officials and will follow any recommendations they make, such as screening passengers before boarding an aircraft. So far, nothing has changed, Castelveter said.

As always, people who are sick should stay away from others. “The buzz word is social isolation, so children who have flu-like symptoms should stay home from school and workers who have flu-like symptoms should stay home from work until they have been fever-free for 24 hours without any drugs,” Beeber said.

Problems carrying out daily chores or enjoying hobbies could predict which people with “mild cognitive impairment” will progress more quickly to Alzheimer’s dementia, U.S. researchers report.

According to the Alzheimer’s Association, mild cognitive impairment (MCI) is “a condition in which a person has problems with memory, language, or another mental function severe enough to be noticeable to other people and to show up on tests, but not serious enough to interfere with daily life.” This type of mental state is considered a risk factor for dementia.

In fact, some studies have found that about 10 percent to 15 percent of those with MCI will progress to dementia each year, according to background information in the new study.

Reporting in the September issue of the Archives of Neurology, the researchers sought to determine if there were telltale signs within MCI that might spot those people who would progress more rapidly to full-blown dementia. To do so, they collected data on 111 people with mild cognitive impairment, then evaluated these individuals using brain scans and cognition tests.

Over the next two years of follow-up, 28 people did go on to develop dementia.

On their own, the tests did not predict which patients went on to develop dementia, said lead researcher Sarah Tomaszewski Farias, an associate professor of neurology at the University of California, Davis.

However, level of daily function was a key predictor, Farias said.

“So, if an older adult is starting to display problems in daily life, such as problems shopping independently, problems managing their own finances, problems performing household chores, and problems maintaining their hobbies, they are more likely to develop a dementia within several years,” she said.

Farias cautioned that the study involved people visiting a clinic because they were already having memory and other problems, so the implications could be different among the general population of older adults.

“If you look at individuals in the community, you see a much slower progression to dementia in those with some mild cognitive impairment,” she said. “The time to develop dementia once someone has mild cognitive impairment is probably slower in the general population of older adults than we had previously thought.”

Still, any kind of early warning is helpful, and Farias believes health-care providers should ask patients and those who know them well — a spouse or adult child — about how they are doing in their daily lives.

“It is important to keep in mind that sometimes individuals themselves lack awareness of some of these problems. So it is important, if at all possible, to get feedback from individuals who are familiar with how the older adult is functioning in their daily life,” she added.

If there is evidence or suspicion that an older adult has some mild cognitive or memory problems, and it is starting to interfere with their ability to do daily activities, there is a higher likelihood this individual is developing a dementia and they should be closely monitored, Farias said.

Greg M. Cole, a neuroscientist at the Greater Los Angeles VA Healthcare System and associate director of the Alzheimer’s Center at UCLA David Geffen School of Medicine, said it is crucial to be able to identify people with early Alzheimer’s disease, “if we want to test methods of preventing it.”

This study illustrates the difficulties in early diagnosis of Alzheimer’s disease in aging people with mild problems with memory and cognition, Cole said.

“In my view, because memory and cognitive performance vary widely in our population no matter what age, the best indications of ongoing decline are going to be seen against past individual performance rather than some cross-sectional ‘normalized’ standard,” he said.

Dr. Ronald C. Petersen, director of the Alzheimer’s Disease Research Center at the Mayo Clinic in Rochester, Minn., agreed that, despite the lack of effective treatments, spotting Alzheimer’s disease early remains important.

“If people in the family start to recognize a change in memory/learning patterns, that might be sufficient to identify someone who could develop Alzheimer’s disease,” Peterson said. “Don’t wait until the person is having trouble driving, is having trouble paying their bills or having trouble functioning in the community — that’s dementia,” he said. “This study tells us that we can identify important symptoms earlier and it may be worthwhile doing so.”