Kids' 'Screen Time' Linked to Early Markers for Cardiovascular Disease

Six-year-olds who spent the most time watching television, using a computer or playing video games had narrower arteries in the back of their eyes -- a marker of future cardiovascular risk, in a first-of-its-kind study reported in Arteriosclerosis, Thrombosis and Vascular Biology: Journal of the American Heart Association.

Australian researchers found that more sedentary behavior such as "screen time" was associated with an average narrowing of 2.3 microns in the retinal arteriolar caliber. A micron is one thousandth of a millimeter or one-25th of a thousandth of an inch.

In the study, 6- to 7-year-olds who regularly participated in outdoor physical activity had 2.2 microns wider average retinal arteriolar compared to those children with the lowest level of activity.

The magnitude of the narrowing associated with each hour of television/computer viewing was similar to that associated with 10 millimeters of mercury (mm HG) increase in systolic blood pressure in children, researchers said.

"We found that children with a high level of physical activity had a more beneficial microvascular profile compared to those with the lowest levels of physical activity," said Bamini Gopinath, Ph.D., lead author and senior research fellow at the Center for Vision Research at the University of Sydney. "This suggests that unhealthy lifestyle factors may influence microcirculation early in life and increase the risk of cardiovascular disease and hypertension later in life."

Retinal microvascular caliber is a marker for cardiovascular disease and high blood pressure in adults. But this is the first time that a sedentary lifestyle in childhood showed a narrowing of the vessels in the retina that could be a subclinical marker for cardiovascular disease in the future.

The study included 1,492 children in 34 primary schools in Sydney, Australia. Parents answered a 193-item questionnaire, providing the number of hours spent each week in indoor and outdoor physical activity and sedentary activity such as watching television, video games, computer time and reading.

Researchers took digital photographs of the vasculature in the back of each child's eye, then calculated average retinal vascular calibers. Height, weight, body mass index (BMI) and three separate blood pressure measurements were taken and averaged.

On average, the children spent 1.9 hours per day in screen time and 36 minutes a day in total physical activity. Children in the highest levels of physical activity at just over an hour or more had significantly wider average retinal arteriolar caliber than those spending just under half an hour or less per day.

Increased screen time was associated with narrower average retinal arteriolar diameter after adjusting for age, sex, ethnicity, iris color, length of the eyeball, BMI, birth weight and blood pressure. Each hour per day of TV viewing time was associated on average with 1.53 microns narrower retinal arteriolar caliber.

"Excessive screen time leads to less physical activity, unhealthy dietary habits and weight gain," Gopinath said. "Replacing one hour a day of screen time with physical activity could be effective in buffering the effects of sedentariness on the retinal microvasculature in children. Free play should be promoted and schools should have a mandatory two hours a week in physical activity for children."

Physical activity enhances endothelial function and increases blood flow resulting in enhanced nitric oxide production, which has a positive effect on the linings of blood vessels.

The researchers said their findings might not be applicable to other regions of the world because of the temperate climate in Australia, where children are more apt to play outdoors. Study limitations included the use of parental rather than objective measurement of the children's time spent in physical and sedentary activities.

"Parents need to get their children up and moving and off the couch," Gopinath said. "Parents can also lead the way by being more physically active themselves."

Co-authors are: Louise A. Baur, Ph.D.; Jie Jin Wang, Ph.D.; Louise Hardy, Ph.D.; Erdahl Teber, Ph.D.; Annette Kifley, M.B.B.S.; Tien Y. Wong, M.D., Ph.D.; and Paul Mitchell, M.D., Ph.D. Author disclosures are on the manuscript.

Australian National Health and Medical Research Council, Westmead Millenniun Institute and Vision Co-operative Research Centre funded the research.

Does Video Game Violence Harm Teens? New Study Weighs the Evidence

How much scientific evidence is there for and against the assertion that exposure to video game violence can harm teens?

Three researchers have developed a novel method to consider that question: they analyzed the research output of experts who filed a brief in a U.S. Supreme Court case involving violent video games and teens.

Their conclusion? Experts who say violent video games are harmful to teens have published much more evidence supporting their claims than have experts on the other side of the debate.

"We took what I think is a very objective approach: we looked at the individuals on both sides of the debate and determined if they actually have expertise in the subjects in which they call themselves experts," said Brad Bushman, co-author of the study and professor of communication and psychology at Ohio State University.

"The evidence suggests that those who argue violent video games are harmful have a lot more experience and stronger credentials than those who argue otherwise."

Bushman conducted the study with Craig Anderson, professor of psychology at Iowa State University, and Deana Pollard Sacks, professor of law at Texas Southern University. Their research will be published in May in the Northwestern University Law Review Colloquy.

Their study involved Schwarzenegger v. Entertainment Merchants Association, a case before the U.S. Supreme Court that will decide whether the state of California can ban the sale or rental of violent video games to children under 18. The court is expected to rule on the case this summer.

In this case, groups supporting and opposing the law have filed what are called briefs of amicus curiae. These are briefs by people or groups who are not involved directly in the case, but want to offer the court their expert opinion on the issues involved.

The researchers analyzed the credentials of the 115 people who signed the Gruel brief, who believe video violence is harmful, and the 82 signers of the Millett brief, who believe video violence is not harmful. (The briefs are named after the lead attorneys for each side.)

The data for the study came from the PsycINFO database, which provides more than 3 million references to the psychological literature from the 1800s to the present, including peer-reviewed journal articles, book chapters or essays, and books.

For each of the signers of the two briefs, the researchers calculated how many articles and books they published on issues relating to violence and aggression in general and on media violence specifically.

The results showed that 60 percent of the Gruel brief signers (who believe video game violence is harmful) have published at least one scientific study on aggression or violence in general, compared to only 17 percent of the Millett brief signers.

Moreover, when the researchers looked specifically at the subject of media violence, 37 percent of Gruel brief signers have published at least one study in that area, compared to just 13 percent of the Millett brief signers.

In a further analysis, Bushman and Anderson examined where the signers of both briefs have published their research. The best academic journals have the highest standards and the most rigorous peer review, so only the best research should be published there, Bushman said.

The researchers used a well-established formula, called the impact factor, to determine the top-tier journals, and then calculated how many signers had published in these journals.

Results showed that signers of the Gruel brief had published over 48 times more studies in top-tier journals than did those who signed the Millett brief.

"That's a staggering difference," Bushman said. "It provides strong support for the argument that video game violence is indeed harmful."

Bushman said he and his colleagues did this study because they wanted to show that there is a way for the Supreme Court to evaluate the contradictory evidence it has been presented.

"The justices were presented with two briefs, arguing opposite sides, and they may think the contradictory briefs simply cancel each other out," Bushman said.

"We just wanted to point out to the justices that not all briefs are the same. In this case, the credentials and experience of those who signed the Gruel brief far exceeds that of the ones who signed the Millett brief."

New Approach to Defeating Flu Shows Promise

New research on mice has shown that pulmonary administration of granulocyte macrophage-colony stimulating factor (GM-CSF) significantly reduces flu symptoms and prevents death after a lethal dose influenza virus. While GM-SCF therapy for humans as a flu prophylaxis or treatment may be years away, the study results were striking: All of the mice treated with GM-SCF survived after being infected with the influenza virus, whereas untreated mice all died from the same infection.

"Such unique and unambiguous results demonstrate the great potential of GM-CSF and may be the remedy for a critical public health priority: developing strategies to reduce the morbidity and mortality from influenza," said Homayoun Shams, PhD, principal investigator of the study.

The results were posted online ahead of the print edition of the American Journal of Respiratory and Critical Care Medicine.

Each year, flu infects 3 to 5 million people worldwide and is responsible for 250-500,000 deaths, according to the World Health Organization. Genetic mutations of influenza virus reduce the potency of flu vaccines, and a vaccinated person may contract flu, develop complications and even die due to poor host immune responses to vaccine or mutated virus strains.

Vaccinations work by activating the host's adaptive immunity in advance of infection. However, if the immune system is compromised, a vaccination may not provoke an adequate immune response to confer protection. Additionally, vaccine-induced immunity takes time to develop. If an individual is exposed shortly before or after being vaccinated, the vaccine will likely have little or no effect on his or her immunity.

"Improved methods to protect against influenza are sorely needed, particularly in the face of an impending pandemic. Development of such methods hinges on understanding host mechanisms that confer robust protection against influenza," said Dr. Shams. "Despite the widespread use of vaccines, influenza causes significant morbidity and mortality throughout the world, and those with poor immune systems are particularly more susceptible -- such as very young, elderly or immunocompromised individuals."

GM-SCF boosts innate immunity to make it immediately effective against the virus, and its protective effect has not been shown to be strain dependant so far. Alveolar macrophages (AM), which are enhanced by GM-SCF, are an essential piece of the innate immune response and are known to contribute to host defense against flu infections in animal models.

"Unlike a vaccine, GM-SCF does not rely heavily on the body's ability to mount an immune counter-attack against a specific antigen or virus strain, but enhances the speed of local responses to virus infection and delicately balances the host immune responses," explained Dr. Shams.

Dr. Shams and colleagues wanted to test the idea that boosting AM by introducing GM-SCF would protect against flu. They used three types of mice to test their hypothesis: wild-type (WT) mice, transgenic mice that do not express any GM-SCF (GM-/-), and transgenic mice that express GM-SCF only in the lung (SPC-GM). They infected all three strains of mice with lethal doses of influenza virus. After progressive weight loss, all WT and GM-/- mice died within days. In contrast, all SPC-GM mice survived, and they gained back the weight they initially lost after a short period.

"This proves the concept that GM-SCF, only in the lung, is sufficient to provide complete protection against infection with otherwise lethal doses of influenza virus strains," said Dr. Shams. "This finding delineates a novel means of conferring marked resistance to influenza through enhancing innate immune mechanisms that depend on AM. We found that SPC-GM mice that overexpress GM-SCF only in the lungs are highly resistant to infection with laboratory and clinical influenza strains, including the recent pandemic swine H1N1 strain."

GM-SCF is already in use in humans as a therapy for neutropenia, and Dr. Shams hopes to eventually test its effectiveness in clinical trials for preventing or treating flu exposure. "If additional work determines that delivery of GM-SCF to the lungs after onset of symptoms improves the outcome of influenza infection, this strategy has great potential to represent a new intervention to reduce morbidity and mortality from influenza in humans," he said.

Japan plagued by aftershocks -- 27 of them magnitude 6 or greater

Since Friday's 8.9 quake, Japan has experienced more than 154 aftershocks of magnitude 5 or greater, and 27 of magnitude 6 or greater, an official with the U.S. Geological Survey says. But he says it would take an aftershock of at least a magnitude 7 to generate a tsunami.

Japan continued to be rocked by aftershocks Saturday following Friday's 8.9 magnitude earthquake.

The nation has experienced more than 154 aftershocks of magnitude 5 or greater since the earthquake, according to Paul Caruso, a geophysicist with the U.S. Geological Survey earthquake information center in Golden, Colo. Of the aftershocks, 27 have been magnitude 6 or greater, Caruso said.