Researchers believe they have identified a fundamental cause of aging, according to a study published this week in the journal Cell. The mechanism was previously found in fungus and has now been discovered in mice. It's likely that the same process applies to humans, said the authors of the research, from Harvard.
The study found that DNA damage, which accrues as we age, decreases a cell's ability to regulate which genes are turned on and off in particular settings. Though DNA damage speeds up aging, the actual cause is not the DNA damage but the lack of gene regulation. However, this lack of gene regulation, called epigenetics, may be reversible.
The study focused on a group of genes called sirtuins that are involved in the aging process. Sirtuins respond to DNA damage to repair it but appear to become overwhelmed as DNA damage accumulates during aging. When DNA damage accumulates, the sirtuins became too distracted to properly regulate gene activity. This was found in yeast about 10 years ago. The new study shows it also occurs in mice.
But when stimulated by either the chemical in red wine, resveratrol, or by caloric restriction, sirtuins appear to function better. In the study, researchers administered extra copies of the sirtuin gene, or fed resveratrol to mice that were genetically altered to develop lymphoma. That extended their lifespan by 24% to 46%.
"We see here, through a proof-of-principal demonstration, that elements of aging can be reversed," said one of the researchers, Philipp Oberdoerffer, in a news release.
People are often advised to avoid making important decisions when they're under a lot of stress. Now a study on rats shows too much stress can lead to cloudy thinking.
University of Washington researchers presenting their work at this week's annual meeting of the Society for Neuroscience found that stressed rats took much longer to respond to a change in rewards given to them in a maze and performed worse than those not exposed to stress. After the changes were made to the rats' maze, those that weren't exposed to stress collected the new reward on 35 out of 40 trials. But rats that were stressed (with a series of unpredictable tail shocks for one hour) were only successful on about 23 of 40 trials. Even after several more days, their performance increased only to 26 out of 40 trials.
Even one episode of stress can cause long-lasting cognitive impairment, concluded the researchers, Lauren Jones, a psychology doctoral student, and Jeansok Kim, an associate professor of psychology.
"Decision-making, both large and small, is part of our lives," Kim said in a news release. "People are prone to make mistakes under stress. Look at what has been going on with the stock market. People are under huge amounts of stress and we have to question some of the decisions that are being made."
Have you seen all those gorgeous grapes in the grocery stores these days? Eat 'em. They may help you with high blood pressure that results from a salty diet.
Research published this week in the Journal of Gerontology: Biological Sciences, examined rats from a research breed that develops high blood pressure when fed a salty diet. The rats were fed a mixture of green, red and black table grapes in powdered form along with their regular salty diet. When the grape-fed rats were compared 18 weeks later with control-group rats, who ate a salty diet without grapes, they were found to have lower blood pressure, better heart function, reduced inflammation throughout their bodies and fewer signs of heart muscle damage. Some of the rats in the control group received a blood-pressure medication. Those rats had lower blood pressure but their hearts weren't protected from damage as were the grape-fed rats.
"These findings support our theory that something within the grapes themselves has a direct impact on cardiovascular risk, beyond the simple blood pressure-lowering impact that we already know can come from a diet rich in fruits and vegetables," said Mitchell Seymour, who led the research as part of his doctoral work in nutrition science at Michigan State University.
The rats in the study mimic the condition of many Americans who develop hypertension because of their diet and then develop heart failure over time because of prolonged hypertension, the researchers noted. But the addition of the grape powder changed the trajectory of the rats' health.
Here's a gee-whiz fact: The control of mammalian blood pressure depends on a gas that smells like rotten eggs -- hydrogen sulfide. So we learn from a study of mutant mice published this week in the journal Science. Researchers genetically engineered mice to under-produce hydrogen sulfide, which is made by the endothelial cells lining blood vessels. They measured the animals' blood pressure using tiny blood pressure cuffs applied to the animals' tails. The result: hypertensive mice.
Hydrogen sulfide, it appears, acts to relax blood vessels, and if the mouse doesn't make the gas it can't control its blood pressure.
Hydrogen sulfide is thus the latest gas found to do useful stuff in the body. (Scientists call these useful gases "gasotransmitters.") Others are carbon monoxide and nitric oxide, the latter famously involved in blood pressure control, including the production of erections. Perhaps hydrogen sulfide has an involvement there too.
All those sugary sodas, those *fructose-laden (high-fructose corn syrup, as stated in an earlier version of this article, was not used in the study) candy bars and cereals might be delivering a double whammy in setting people up for obesity, assuming that people are a little like rats.
In rats, researchers from the University of Florida have reported in the American Journal of Physiology, a high-fructose diet blocks the appetite-controlling hormone leptin.
So it's not just the fructose, a sugar found in moderate amounts naturally in fruits and vegetables, and in large amounts in the form of high-fructose corn syrup in many processed foods, that packs the pounds on. *(Though the Corn Refiners Assn. would like you to know that there are differences between fructose and high-fructose corn syrup in that, like table sugar, the syrup contains roughly equal amounts of fructose and corn syrup. For the industry's arguments, see its fact sheet or press release.) The Department of Agriculture found that the consumption by Americans of high-fructose corn syrup increased by 1,000% from 1970 to 2000. It may be that a high-fructose diet makes the eater resistant to leptin, interfering with the body's internal attempt to balance food intake and energy expenditure. The "I'm not hungry" signal fails to go off, and rats, at least, forget how to push their little chairs away from the table.
Scientists have long linked leptin resistance to obesity, but the new study is the first to link fructose and leptin resistance.
The researchers studied two groups of rats, each group receiving the same amount of calories, according to a news release. But one group ate rat chow that contained 60% fructose, while the other was on a fructose-free diet. During that phase of the study, all remained equal. Both groups had identical body weight and fat as well as blood levels of leptin, insulin, glucose and cholesterol. The only difference was that high-fructose eaters had higher levels of blood triglycerides.
Then the researchers tested how each group of rats responded to leptin, and they discovered that those eating the high-fructose diet had become resistant to the hormone. When both groups were switched to a high-fat diet, those who had earlier eaten the high-fructose diet got fat, while the fructose-free group didn't.
"Fructose sets you up," says Philip J. Scarpase, professor of pharmacology and therapeutics at the UF College of Medicine and lead author of the study. "If these findings are applicable to humans, then there could be consequences of eating a diet high in fructose, but only if you also consume an excessive amount of calories. If you go on a trip, attend a celebration, or otherwise eat more than you usually eat, a person consuming a low-fructose diet may be able to handle it. But the individual who has set themselves up so that leptin no longer works will be unable to burn the extra calories, and now they gain a lot of weight."
The findings, so far, apply only to rats. But suddenly, that weight gain after those out-of-town celebrations are starting to make a lot more sense to me.
A classic way that researchers teach mice to be afraid is to sound a tone and immediately follow it with a small electric shock to their paws. Scientists can then study what fear and anxiety do to the brain. It doesn't take long before the mice become anxious and afraid at the sound of the tone, even without the follow-up shock.
Recently, though, scientists have found that they can teach mice a kind of calm fearlessness, even in a stressful situation, getting from them the same response as, say, a dose of Prozac. "It's a little bit like psychotherapy," Eric Kandel said in a news release. He's the lead author of a study in the Oct. 8 journal Neuron, and an investigator at the Howard Hughes Medical Institute. "This shows that behavioral intervention works."
Here's what they did. They taught mice learned safety, pairing a tone with uneventful calmness and safety. These mice learned to associate the tone with absence of danger.
Then it was into the little mouse swimming pool for everyone, normally a pretty stressful situation for any critter who can't figure out how to get out of the water. The swimming mice, not surprisingly, normally become desperate. Earlier research has shown that antidepressants help rodents remain calm, even in the stressful swimming pool.
The new experiment showed that mice who had gone through learned-safety training remained calm, even in the swimming pool.
"In this seemingly desperate situation –- where the mice have no option to escape from the water -- they start to show signs of behavioral despair that are ameliorated by antidepressant medications. We found that the mice trained for safety could overcome their sense of hopelessness in the swim test," Kandel explained.
The antidepressant effect in the safety-conditioned mice was similar and comparable in magnitude to treatment with the drug fluoxetine (Prozac), Kandel noted in the release.
After analyzing the brains of the mice who had been through safety training, researchers were intrigued to find that the training did not affect serotonin, the brain chemical targeted by many antidepressants. Rather, learned safety affected dopamine and neuropeptide neurotransmitters, suggesting new targets for antidepressant drug development.
Overeating not only makes your body expand, it sends your brain off-kilter, say the authors of a new study on obesity. The study, from researchers at the University of Wisconsin-Madison, showed that a part of the brain that is normally dormant can be activated by too many calories.
Previous research has shown that over-nutrition causes an inflammatory response in many tissues in the body. This inflammation can lead to diseases like diabetes. A particular molecular compound called IKKbeta/NK-kappaB is known to promote this inflammation. But by giving mice loads of sugar or fat, the same molecular compound was activated in their brains. That, in turn, caused dysfunctions in the way they handled nutrition, such as changes in the important metabolic hormones insulin and leptin. Insulin lowers blood sugar while leptin controls appetite.
Researchers think that this normally inactive pathway in the brain may have been important in our evolutionary past, perhaps by boosting the body's immunity. But it's definitely something modern-day humans want to avoid. So go easy on that never-ending pasta bowl.
"In today's society, this pathway is mobilized by a different environmental challenge -- over-nutrition," said Dongsheng Cai, the lead author of the study. "The pathway leads to a number of dysfunctions."
The study also found that treatments that prevent the activity of IKKbeta/NF-kappaB in the animals' brains protected them from obesity. Scientists now hope they can create treatments to block this pathway in humans. The study was published in the journal Cell.
Scientists can do a lot with mice. They can, for example, engineer them so that their stem cells glow green. Why would anyone do that, you ask? Well, in the case of mice in a laboratory at the University of Texas Southwestern Medical Center, it was to watch baby fat cells as they grew into fully developed fat cells.
They knew that immature fat cells hang back and wait for excess calories, growing into adult fat cell monsters that make it so easy to pack on extra pounds, so hard to lose them.
But scientists didn't know exactly where those cells were hiding. "Identifying the progenitor cells and finding where they live gives us an exciting therapeutic opportunity," says Dr. Jonathan Graff, senior author of the study, which appears in the online edition of the journal Science. Turns out, the cells are embedded within blood vessel walls that run through fatty tissue.
These cells do more than just grab excess calories and store them as fat. When people take in more calories than they burn off, these cells procreate, producing more and more fat cells. Finding where the fat-hungry cells hang out in mice eventually could help to develop therapies in humans to reduce obesity.
Or scientists might develop ways to use the immature fat cells to benefit people in other ways. For example, progenitor cells from a fatty thigh or belly might be moved to a soldier's wounds or a woman's breast cancer scar to help fill out and heal.
Obstructive sleep apnea causes a world of problems, one being erectile dysfunction. New research, however, makes some interesting observations about the connection between the two problems.
People with sleep apnea have periods of time during sleep when they stop breathing. Working with mice, researchers at the University of Louisville have discovered that oxygen deprivation appears to be the cause of the ED. They exposed mice to one week of oxygen deprivation episodes that mimic those seen in sleep apnea patients. The mice had a decline in daily spontaneous erections and took much more time to, ahem, make contact with their female friends. The study is published in the current issue of American Journal of Respiratory and Critical Care Medicine, which is a publication of the American Thoracic Society.
The good news is it that the researchers were able to reverse the ED in mice after giving them tadalafil (which is known by the brand name Cialis). Future research is needed to better understand how the oxygen deprivation experienced in obstructive sleep apnea patients affects the part of the central nervous system that influences sexual drive.
"Exploration of alternative interventions aiming at preventing and treating this infrequently spoken of, yet extremely frequent complication of obstructive sleep apnea, will certainly require improved understanding of the complex mechanisms affecting sexual activity and how it is affected by diseases such as sleep apnea," said Dr. David Gozol, the lead author of the study and a professor of pediatrics at the University of Louisville.
As a consumer-focused section, Health rarely writes about animal studies because it's impossible to say if the study results can be extrapolated to human health. That said, the findings from animal studies are often too cool to ignore. That's why we'll present a pick-of-the-litter animal study each Friday in Booster Shots. The item may tell you nothing of certainty about your own health. But you're likely to learn a lot about rats and mice. Enjoy.
A medication that has been used to help athletes cheat appears to help mice with their memory. Erythropoietin, also commonly known as EPO, is an interesting medication. A hormone that controls red blood cell production, it's used to treat anemia in people undergoing chemotherapy or with chronic kidney failure. Some athletes have used it to improve their performances, although it is banned from most athletic competitions.
Researchers have observed that when EPO is given to people with chronic kidney failure it seems to improve their cognition. A new study published in BMC Biology, however, suggest the drug acts in the brain to improve memory and cognition. Investigators gave mice EPO for three weeks and compared them to mice who didn't receive the drug. The EPO mice performed better on memory tests than the other mice, an effect that lasted up to three weeks after the last EPO dose. Researchers have guessed that EPO improves memory by boosting blood production. But when the scientists examined the brains of the EPO mice, they found changes in the neurons in the hippocampus area of the brain.
Tami Dennis, who takes the word "skeptic" to previously uncharted territory, is editor of The Times' Health section. She's adamant that pitches promoting awareness days, weeks or months are, by their nature, non-stories. And, because she's an adult, she refuses to use words like "veggies," "tummy" and "yummy."
Rosie Mestel, Health section deputy editor, studied genetics before abandoning flies, fungi and DNA for health/medical writing. Her hero is the biologist Ernst Haeckel, whose jellyfish paintings inspired snazzy chandeliers. Her favorite toast-spread is Marmite, a British delicacy made of yeast extract. Her least-favorite word is "millenniums."
Melissa Healy is a staff writer for the Health section reporting from Washington D.C. Healy's a veteran of The Times' National staff, having covered the Pentagon, Congress, poverty and social welfare, the environment, and the White House before shifting to Health in 2003. She writes frequently about mental health and human behavior, about federal health policy, prescription medication and ethics in medicine. More wonk than wellness freak, Healy chooses to believe in the health benefits of coffee and wine, and considers water a better work-out medium than beverage.
After a brief stint as a sports writer, Shari Roan turned to health journalism and has covered the topic for The Times for 18 years. She is the author of three books and the mother of two daughters, both teenagers who refer to her as a "health freak." She likes to jog, watch baseball and is very happy that dark chocolate contains some health benefit.
Jeannine Stein writes about fitness, sports medicine and obesity for the Health section. She’s a gym rat from way back and never met an elliptical trainer she didn’t like. Well, maybe one or two. She tempers exercise with a steady diet of reality television because she believes it’s all about balance.
Researchers believe they have identified a fundamental cause of aging, according to a study published this week in the journal Cell. The mechanism was previously found in fungus and has now been discovered in mice. It's likely that the same process applies to humans, said the authors of the research, from Harvard.
People are often advised to avoid making important decisions when they're under a lot of stress. Now a study on rats shows too much stress can lead to cloudy thinking.
Have you seen all those gorgeous grapes in the grocery stores these days? Eat 'em. They may help you with high blood pressure that results from a salty diet.
Here's a gee-whiz fact: The control of mammalian blood pressure depends on a gas that smells like rotten eggs -- 
In rats, researchers from the University of Florida have reported in the American Journal of Physiology, a high-fructose diet blocks the appetite-controlling hormone leptin.
A classic way that researchers teach mice to be afraid is to sound a tone and immediately follow it with a small electric shock to their paws. Scientists can then study what fear and anxiety do to the brain. It doesn't take long before the mice become anxious and afraid at the sound of the tone, even without the follow-up shock.
Overeating not only makes your body expand, it sends your brain off-kilter, say the authors of a new study on obesity. The study, from researchers at the University of Wisconsin-Madison, showed that a part of the brain that is normally dormant can be activated by too many calories.
They knew that immature fat cells hang back and wait for excess calories, growing into adult fat cell monsters that make it so easy to pack on extra pounds, so hard to lose them.
Obstructive sleep apnea causes a world of problems, one being erectile dysfunction. New research, however, makes some interesting observations about the connection between the two problems.
As a consumer-focused section, Health rarely writes about animal studies because it's impossible to say if the study results can be extrapolated to human health. That said, the findings from animal studies are often too cool to ignore. That's why we'll present a pick-of-the-litter animal study each Friday in Booster Shots. The item may tell you nothing of certainty about your own health. But you're likely to learn a lot about rats and mice. Enjoy.