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Showing posts with label LiveSciencecom. Show all posts
Showing posts with label LiveSciencecom. Show all posts

Wednesday, February 23, 2011

New Idea to Reduce Global Warming: Everyone Eat Insects (LiveScience.com)

There is a rational, even persuasive, argument for voluntarily eating insects: Bugs are high in protein, require less space to grow and offer a more environmentally friendly alternative to the vertebrates we Westerners prefer, advocates of the bug fare say.
However, this topic is not a hotbed of research, so while some data exist — in particular on the protein content of insects — there are some assumptions built into the latter part of this argument.
"The suggestion that insects would be more efficient has been around for quite some time," said Dennis Oonincx, an entomologist at Wageningen University in the Netherlands. He and other researchers decided to test it, by comparing the greenhouse gas emissions from five species of insects with those of cattle and pigs.
The results, Oonincx said, "really are quite hopeful."
Untapped potential
For much of the world, eating insects — officially called entomophagy — is neither strange nor disgusting nor exotic. In southern Africa, Mopani worms — the caterpillars of Emperor moths — are popular snacks. The Japanese have enjoyed aquatic insect larvae since ancient times, and chapulines, otherwise known as grasshoppers, are eaten in Mexico. But these traditions are noticeably absent in Europe and European-derived cultures, like the United States.
Insects' nutritional content, small size and fast reproduction rates have also made them appealing solutions to problems traditional agriculture can't solve. For instance, a task force affiliated with the Japanese space agency has looked to insects like silkworms and termites as a self-replenishing supply of fats and amino acids for astronauts on extended missions.
For children from 6 months to 3 years of age, low calories and low protein are the main causes of death, about 5 million a year, according to Frank Franklin, a professor and director of pediatric nutrition at the University of Alabama at Birmingham. Protein from insects could offer a less expensive solution if processed into a form similar to Plumpy'Nut, a peanut-based food for those suffering from malnutrition, he said.
Franklin embraced the arguments for entomophagy after learning about it roughly a year ago.
"The more I looked at it, the more it made incredible sense that this would be an important nutritional advance that is only going to bring back what has probably been there since the primitive man," he told LiveScience.
The comparison
A 2006 report by the U.N.'s Food and Agriculture Organization blamed the livestock sector for a sizable portion of humans' greenhouse gas emissions – 9 percent of our carbon dioxide emissions (much of this originates in changes in land use), 37 percent of our methane and 65 percent of our nitrous oxide emissions.
Oonincx and his colleagues used two important livestock animals, pigs and cattle, and compared existing data on their emissions of these greenhouse gases, plus ammonia, with data they collected from five species of insects: mealworms, house crickets, migratory locusts, sun beetles and Argentine cockroaches. The latter two species are not considered edible, at least not directly. Their taste is just not good, Oonincx said, however, protein extracted from them could be added to foods.
To quantify the animals' greenhouse gas footprints, the team measured the five insects' growth rates and their production of the greenhouse gases and ammonia — also a pollutant but not a greenhouse gas. They compared these to data already available on the cattle and pigs' growth rate and the rates at which they emitted the same pollutants.
Cattle produced the least carbon dioxide per unit of body mass. However, the picture changed once growth rate was considered. The data indicated that insects grow more rapidly, and they emit less carbon dioxide per unit of weight gained than do cattle and pigs. The cockroach was the clear winner in this latter category; meanwhile, cattle produced the most carbon dioxide per pound (or kilogram) gained. [The Truth about Cockroaches]
The insects generally produced less methane, nitrous oxide and ammonia both per unit of body mass and per unit of mass gained than pigs or cattle.
"It proves the hypothesis that insects can be a more efficient source [of protein], and I definitely believe there is a future for edible insects," Oonincx said. "It may not be as the animal as such but regarding protein extraction there is a lot to be learned and a lot to be gained."
Solving the livestock problem
There are strategies that can reduce greenhouse gas emissions associated with raising livestock but these improvements can't bring about reductions necessary to meet emissions targets intended to curb global warming, write the authors of a paper published in the medical journal the Lancet in November 2009.
Their solution: a 30 percent reduction in livestock production, and therefore, a drop in meat consumption. This would mean diets with less saturated fat and fewer premature deaths caused by heart disease, they write. (The researchers note that not everyone needs to reduce meat consumption; agriculture produces enough fat, protein and other nutrients to feed all of us, but food isn't distributed equally, resulting in malnutrition and starvation in some places.)
A policy that reduces our hamburgers and barbeque is likely to encounter resistance, one of the authors, Alan Dangour, of the London School of Hygiene & Tropical Medicine, acknowledged. However, so will a push to switch to insects, he told LiveScience in an e-mail.
"It is clearly worthwhile investigating alternative sources of high-quality protein," Dangourwrote. "However, the practical barriers to eating insects (in Westernized societies) are extremely large and perhaps currently even likely to be insurmountable."
David Gracer, an American advocate for entomophagy who co-organized a conference on the subject in December, welcomed the findings.
"It is wonderful to see science showing the world that what is instinctively apparent is actually factually correct," Gracer said. "The point is that most scientists in Western nations are too busy ignoring this subject to go ahead and take it seriously, and as soon as people do so, the experiments simply reinforce what we already assumed was true."
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Scientists Monitor Killer Mice … From Space (LiveScience.com)

NASA satellites hovering hundreds of kilometers above the Earth may now be able to track a very terrestrial threat: mice.
According to a new study published Wednesday (Feb. 16) in the journal Global Ecology and Biogeography, satellite images showing changes in vegetation (food for mice) can be used to predict the risk of mouse-borne disease outbreaks. Flourishing vegetation generally means a mouse baby boom, and that, in turn, means more rodents carrying hantavirus, a respiratory disease that can be fatal when spread to humans.
The method "potentially could be applied to any animal that responds to vegetation," study co-author Denise Dearing, a biologist at the University of Utah, said in a statement. "It would have to be calibrated against each specific species of rodent and the disease, but it's really powerful when it's done."
Other diseases spread from wild animals to humans include rat-bite fever, Lyme disease and bubonic plague, Dearing said.
Hantavirus and hantanauts
Hantavirus is an ailment spread when people inhale dust containing mouse feces or urine. Only 503 human cases of hantavirus were reported between 1993 and 2009, according to the Centers for Disease Control and Prevention, but the disease is serious: About 36 percent of cases were fatal.
Dearing and her colleagues wanted a way to not just track outbreaks, but to predict them. The research team set about collecting two types of data. First, they trapped hundreds of mice during six field expeditions over three years. Each mouse was tagged and tested for the disease before being released.
When trapping first began, the researchers feared contracting hantavirus by handling the trapped rodents. To protect themselves, they initially donned biohazard suits that look like spacesuits, earning the nickname "hantanauts." After medical researchers learned that hantavirus isn't easily transmitted by handling mice (people usually get it when cleaning out dusty, enclosed spaces contaminated with mouse feces), the research team was able to ditch the suits.
Second, the team pulled data from MODIS, or the Moderate Resolution Imaging Spectroradiometer, a sensor on NASA's Terra satellite. The MODIS images of the field area in Juab County, Utah, were analyzed to measure the green light reflected by plants' leaves and the infrared light that plants absorb. More green and less red meant more vegetation.
Disease-monitoring from space
The researchers expected the mouse population to surge after vegetation peaked, but they didn't know how long it would take. They tested correlations between vegetation and the number of trapped and infected mice at about three-and-a-half months after a vegetation peak, one year after, and one year and three-and-a-half months after.
They found that the mouse population boomed one year after a vegetation surge and then boomed again three-and-a-half months after that. The proportion of hantavirus-infected mice trapped didn't change, but the absolute number of infected mice went up along with the population.
"You can think of it as a kind of air drop of food for the mice," study co-author Thomas Cova, a geography professor at the University of Utah, said in a statement. "It's rained and suddenly there's just so much food that they're rich. They get fat, population density goes up, and about a year-and-a-half later, population peaks."
Because the satellite vegetation images so clearly predict mouse population booms, health officials could use the information to pinpoint where hantavirus outbreaks are most likely to occur.
"Although the focus of this work is hantavirus in deer mice, it contributes to our broader understanding of how to monitor the spread of infectious diseases from space, which in the long run could save lives," Cova said.
You can follow LiveScience Senior Writer Stephanie Pappas on Twitter @sipappas.
View the original article here

Monday, February 14, 2011

Pot Use May Mellow Out Men's Sexual Function (LiveScience.com)

Marijuana users sometimes report that pot enhances their desire for sex. But a new review of research on marijuana and sexual health suggests that male smokers could be courting sexual dysfunction.

Research on the topic is contradictory and few studies are high-quality, said study researcher Rany Shamloul, a physician with appointments at the University of Ottawa and Queen's University in Canada as well as the University of Cairo. But recent research – including the finding that the penis contains receptors for marijuana's active ingredient  – suggests that young men may want to think about long-term effects before rolling a joint, Shamloul told LiveScience.

"It's a strong message to our younger generations and younger men," Shamloul said.

Shamloul reported his findings online Jan. 26 in the Journal of Sexual Medicine.

Sex and drugs

Scientists first began to study marijuana and sex in the 1970s. Some researchers found that cannabis seemed to have the effect of a love drug; in one 1982 study published in the Journal of Psychoactive Drugs, 75 percent of male pot smokers said the drug enhanced their sex lives. Meanwhile, another study published in the same journal the same year found that erectile dysfunction was twice as common in marijuana users – not such good news for lit lotharios. Other research suggests a dose effect, in which small amounts of marijuana have little impact on sexual dysfunction, but more marijuana makes for fewer erections.

But problems are rife with this research, Shamloul said, because none of the studies used validated measurement techniques when surveying men about their sexual function. The different questions used could skew the responses, as could the drug itself, he noted in the review. The 39 percent of men in the original 1982 study who said marijuana extended the duration of sex may just have been experiencing the drug's altering effects on the perception of time.

What most concerns Shamloul is a study published in 2010 in the journal European Urology. In that study, researchers found receptors for tetrahydrocannabinol (THC), the active ingredient in marijuana, in penis tissue from five male patients and six rhesus monkeys. These receptors were mainly in the smooth muscle of the penis, Shamloul said. Additional lab studies suggest that THC has an inhibitory effect on the muscle.

"This is a more serious effect on the erectile function because the smooth muscle makes up 70 percent to 80 percent of the penis itself," Shamloul said.

Men and marijuana

Marijuana use is widespread, especially among men at their sexual peak in life, Shamloul said. The United Nations Office on Drugs and Crime reports that 162 million people worldwide use marijuana each year. More than 22 million use it daily. That makes understanding long-term effects important, Shamloul said.

People tend to focus on the possible upsides of marijuana more than the possible downsides, said Sharon Johnson, a professor of social work at the University of Missouri, St. Louis, who has studied marijuana use and sexual health in the past. Her study, published in 2004 in the journal Archives of Sexual Behavior, found that marijuana users have a slightly elevated risk of inhibited orgasms and pain during sex. (Johnson was not involved in Shamloul's review study.)

Research on sexual health and marijuana use in women is even less common than studies in men, Shamloul said.

"What we are really missing are clinical studies," Shamloul said. "We are stuck with only animal studies and molecular studies, and some clinical studies done in the '60s and '70s, most on a very small number of men… We need well-designed, placebo-control studies examining marijuana's effect in both the short-term and long-term."

You can follow LiveScience Senior Writer Stephanie Pappas on Twitter @sipappas.


View the original article here