Archive for February 5, 2008

Oh No! Irregular Exercise Patterns May Add Pounds!

BERKELEY, CA — The consequences of quitting exercise may be greater than previously thought, according to a new study from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory that determined that the weight gained during an exercise hiatus can be tough to shed when exercise is resumed at a later date.

The study, conducted by Paul Williams of Berkeley Lab’s Life Sciences Division, found that the key to staying trim is to remain active year-round, year-after-year, and to avoid seasonal and irregular exercise patterns. Most of all, don’t quit. Failure to do so may be a contributing factor in the nation’s obesity epidemic.

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“The price to pay for quitting exercise is higher than expected, and this price may be an important factor in the obesity epidemic affecting Americans,” says Williams, whose study is published in the February issue of the journal Medicine & Science in Sports and Exercise.

The study should prompt people to think twice before taking a break from their exercise regimens, despite the pressures of family and work obligations, or waning motivation.

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Well, then.  Perhaps I better stay away from the exercise entirely if it’s gonna make me gain more weight.   Wish those experts would make up their minds.

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Exotic Pets Can Carry Exotic Diseases

The Centers for Disease Control and Prevention estimate that 60 percent of the currently known human pathogens and 75 percent of emerging infectious pathogens are zoonotic; they include rabies, plague, leptospirosis, tularemia, West Nile virus, Ebola, Marburg, SARS, and Nipah (CDC 2007). Even domestic cats and dogs can serve as a source of human disease, but the risks posed by Fluffy and Fido are well known and understood. These species have been the companions of humans for thousands of years, and, at least in the developed world, most of the risks from them can be controlled: vaccinating prevents the spread of rabies, deworming kills the intestinal parasites that cause ocular or visceral larval migrans, and applying insecticides repels ticks that spread the agent of Lyme disease.Cats and dogs are no longer the only pets found in US homes, however. The Captive Wild Animal Protection Coalition estimates that 10,000 to 20,000 large exotic felids, 17.3 million birds, 8.8 million reptiles, and 3000 great apes are being kept as pets in this country. In 2005 alone, 210 million animals were legally imported into the United States to satisfy the growing demand for exotic species. An unknowable number of pets, animal parts, and meat were smuggled in during the same time period, making up a large part—a portion ranked second only to the illegal drug trade—of the estimated $10 billion per year international black market (Ebrahim 2006).

Introducing so many animals into a new and unnatural environment—our homes—after removing them from the ecosystems in which they evolved represents a disruption of substantial magnitude. This displacement brings these animals into close proximity with species they have not previously encountered, and the public health consequences may be startling.

The most famous, or perhaps infamous, example is the outbreak in the United States of monkeypox in humans, a result of humans’s close contact with prairie dogs sold as pets. Human monkeypox, which in its original environment affects primarily children, has a clinical course similar to that of smallpox, although its fatality rate is lower. This disease, which had not previously been seen outside of Africa (where exposure is thought to take place through contact with wild rodents), was diagnosed in 81 patients in the American Midwest during the summer of 2003. It turned out that Gambian giant rats, imported into the United States for the pet trade, had been housed next to prairie dogs. Asymptomatically infected rats transmitted the virus to the prairie dogs, which then passed it along to the humans who brought them home. Curiously, no suspected, probable, or confirmed cases of monkeypox occurred in humans who had contact only with the Gambian rats, or with any other African rodents (CDC 2003).

Clearly, the surprising thing is not that monkeypox infected US residents, but that such cases have not arisen more often. With our penchant for sharing our living spaces with creatures from foreign lands, outbreaks of other diseases will surely occur. What isn’st clear is how to best protect ourselves.

One approach, the one used most often to augment the generic requirement for a health certificate, is to regulate and legislate for known risks—it is now illegal to import African rodents into the United States, for example. Unfortunately, this approach is reactive rather than proactive, because it relies on the transmission of disease to humans—exactly what we are trying to prevent.

A more proactive alternative would be to regulate the unknown risks—in other words, prevent the importation of species (and thus the pathogens they harbor) that are not well understood. The precautionary principle supports this approach: it puts the onus on the importers and the eventual owners either to prove that a particular species does not have the potential to cause harm, or to provide ways to mitigate any risk. A third approach, a complete ban on importing exotic species for pets, has also been proposed, but is strongly opposed by both potential owners and members of the pet-trade industry. No matter which approach is eventually taken, however, it would be prudent to remember the already vast scale of the illegal market.

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People living in Florida are no strangers to exotic pets being released and then reproducing wildly with no natural predators to keep them in check. As this National Geographic article points out, we are undergoing immense ecological damage from exotic animals imported for the pet market that owners tire of and release, or the animals become too dangerous for the owners and the owners set them free without thinking of, or caring about, the consequences.I would be delighted if the exotic animal trade were shut down tomorrow.   While I may not care if your exotic pet kills your family, I would be very upset about it killing mine.

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Mice Work Out with Weights to Lose Weight

Weight training melts fat and improves metabolism, says study of obese mice
When it comes to losing weight, pumping iron may be just as important as running on the treadmill, suggests a new study in the February issue of Cell Metabolism, a publication of Cell Press.

Researchers used a genetic trick in obese mice that caused the mice’s muscles to bulk up as though they had been lifting weights. The researchers found that the “genetically reprogrammed” mice lost fat and showed other signs of metabolic improvement throughout the body. What’s more, those benefits were seen even though the mice continued eating a diet high in both fat and sugar and didn’t increase their physical activity at all.

“We’ve shown that type II muscle does more than allow you to pick up heavy objects,” said Kenneth Walsh of Boston University School of Medicine. “It is also important in controlling whole-body metabolism.”

The type II, or fast, muscle fibers found plentifully in body builders are well suited to dealing with abrupt and heavy loads. On the other hand, the muscles of long-distance runners are rich in type I, or slow, fibers that can endure lesser loads over longer periods of time. Earlier studies focused primarily on the importance of type I muscle, with its abundance of energy-burning mitochondria, for regulating metabolism, Walsh said. Indeed, those studies have indicated that an increase in “energy burn” in muscle can protect against weight gain and metabolic dysfunction.

“Resistance training builds the white meat,” Walsh said, referring to the relatively mitochondria-poor type II muscle. “There is some evidence it’s good for you, but it’s not immediately clear why. Now, we’ve provided a scientific rationale.”

Walsh’s group developed mice in which they could turn type II muscle growth on or off by flipping a genetic switch specifically in skeletal muscle. The gene they manipulated, known as Akt1, is preferentially activated in skeletal muscle in response to resistance training, but not endurance training, the researchers knew.

Rather than becoming strong and fat “sumo mice” as some of the researchers had expected, the modified mice gained type II muscle and strength while they lost fat. The mice also showed a resolution of hepatic steatosis, otherwise known as fatty liver, and improvements in a variety of other metabolic parameters. The Akt1-driven growth of skeletal muscle counteracted the usual effects of a high-fat, high-sucrose diet on patterns of gene activity in the liver and increased the breakdown of fatty acids there, the researchers showed.

“These findings indicate that type II muscle has a previously unappreciated role in regulating whole-body metabolism through its ability to alter the metabolic properties of remote tissues,” the researchers concluded. “These data also suggest that strength training, in addition to the widely prescribed therapy of endurance training, may be of particular benefit to overweight individuals.”

“The work of [Walsh and his colleagues] reveals the intricate interplay between diet, energy balance, and the function/morphology of diverse tissue systems such as skeletal muscle and liver,” said Brooke Harrison and Leslie Leinwand of the University of Colorado at Boulder in a commentary. “These findings indicate that interventions designed to increase skeletal muscle mass in at-risk human populations may prove to be critical weapons in the fight against obesity and obesity-related comorbidities including diabetes, heart disease, stroke, hypertension, and cancer.”

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The researchers include Yasuhiro Izumiya, Teresa Hopkins, Carl Morris, Kaori Sato, Ling Zeng, Jason Viereck, James A. Hamilton, Noriyuki Ouchi, Nathan K. LeBrasseur, and Kenneth Walsh, of Boston University School of Medicine, Boston, MA.
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Hunh. I had a knee injury a year ago that curtailed both my weightlifting activity AND my cardio activity and in that time, I’ve been engaged in a sedentary occupation that has left me with a double whammy of excess weight and deconditioning. The obstacles to be overcome to get back into shape look as daunting as Mt. Everest.

Maybe, instead of jumping back into exercise with both left feet, I should just work out with weights for a month to get the muscles somewhat used to exercising again and quit trying to lose 30 lbs. in 4 weeks or less. 

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