Well: Ask Well: Weights Before Cardio?

Photo Credit Ariel Zambelich

A

Many dedicated gym-goers have heard that aerobic and resistance-style exercise should not be combined in a single workout; or if they are, that one or the other must come first. The theory behind these claims is that each form of exercise interferes, physiologically, with the other, potentially blunting the desired training effects.

But the best available science disagrees. In an interesting study published in March in the Journal of Applied Physiology, healthy young volunteers vigorously rode a stationary bicycle using one leg and then completed resistance exercises with both legs, meaning that one limb did both types of exercise; the other only weights. After five weeks, both legs had grown equally large and strong. Cycling first had not reduced the impacts of weight training.

Similarly, a 2012 study of sedentary, middle-age men found that they developed specific molecular changes in their leg muscles after riding a stationary bicycle that were distinct from those occurring on a separate day after lower-body weight training. But when the men performed both forms of exercise one after the other (doing half as much of each), they robustly developed both types of molecular responses.

"We saw no indications of interference," said Stuart Phillips, a professor of kinesiology at McMaster University in Hamilton, Ontario, who oversaw the study.

Perhaps most telling, the order of the exercises in these studies was immaterial. In the 2014 study, the men rode and then lifted; in Dr. Phillips's study, they lifted and then rode. Muscles, it seems, "can't tell the difference," Dr. Phillips said.

So don't worry overmuch about which exercise comes when. "Just set up a workout regimen that happens to be convenient for you," Dr. Phillips said.

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Well: Vitamin E and Selenium Fail to Prevent Cataracts

Many health supplement companies, and some medical experts, have recommended vitamin E and selenium for reducing the risk for cataracts. But a large new study has found they are unlikely to provide benefit, though selenium might have a small effect.

Researchers randomly assigned 11,267 men over 50 to four groups of about 2,800 each. Members of one group took a daily placebo, those in the second took 400 IU of vitamin E daily, those in a third took 200 micrograms of selenium a day, and those in the fourth group took both vitamin E and selenium.

The five-year study, published in JAMA Ophthalmology, found 389 confirmed cataracts: 98 in those who took vitamin E, 99 in those who took both supplements, 86 in those who took only selenium, and 106 in the placebo group. None of the differences was statistically significant, though selenium showed a trend that suggests it might have a slight benefit; additional research would be needed.

"The results are consistent with earlier trials of vitamin E," said the lead author, William G. Christen, an associate professor of medicine at Brigham and Women's Hospital in Boston. "They show that for cataracts, the effect is nothing."

But, he added, "These are the first data on selenium alone, and we can't rule out a small but still important effect."

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Well: Ask Well: Weights Before Cardio?

Photo Credit Ariel Zambelich

Ask Well

Your health questions answered by Times journalists and experts.

A

Many dedicated gym-goers have heard that aerobic and resistance-style exercise should not be combined in a single workout; or if they are, that one or the other must come first. The theory behind these claims is that each form of exercise interferes, physiologically, with the other, potentially blunting the desired training effects.

But the best available science disagrees. In an interesting study published in March in the Journal of Applied Physiology, healthy young volunteers vigorously rode a stationary bicycle using one leg and then completed resistance exercises with both legs, meaning that one limb did both types of exercise; the other only weights. After five weeks, both legs had grown equally large and strong. Cycling first had not reduced the impacts of weight training.

Similarly, a 2012 study of sedentary, middle-age men found that they developed specific molecular changes in their leg muscles after riding a stationary bicycle that were distinct from those occurring on a separate day after lower-body weight training. But when the men performed both forms of exercise one after the other (doing half as much of each), they robustly developed both types of molecular responses.

"We saw no indications of interference," said Stuart Phillips, a professor of kinesiology at McMaster University in Hamilton, Ontario, who oversaw the study.

Perhaps most telling, the order of the exercises in these studies was immaterial. In the 2014 study, the men rode and then lifted; in Dr. Phillips's study, they lifted and then rode. Muscles, it seems, "can't tell the difference," Dr. Phillips said.

So don't worry overmuch about which exercise comes when. "Just set up a workout regimen that happens to be convenient for you," Dr. Phillips said.

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Well: A Doctor, a Rabbi and a Chicken

Photo Credit Keith Negley

"Doctor, is it O.K. for our rabbi to visit my father?"

I was an intern on call in one of the internal medicine wards in an Israeli hospital just south of Tel Aviv. The first day of the Jewish holiday of Sukkot had just ended, and the ward was beginning to fill up with visitors who had been unable to drive until after sunset.

Looking up from what I was doing, I saw the son of one of my patients standing at the counter of the nursing station. He and I had already spoken several times that day about his 75-year-old father, who had been admitted the night before because of a stroke.

The father's CT scan from the night before had been unremarkable, not unusual in patients whose strokes are caused by an interruption of blood flow to portions of the brain. I had explained this to the son, as well as what to expect over the next few days as his father would undergo further testing and then discharge to a rehabilitation facility. I told him that it was impossible at this early stage to predict how much function his father might recover, and cautioned against giving him anything to eat or drink until we were certain that his ability to swallow had not been affected. All of the son's questions had been very appropriate and focused.

"Of course," I responded, smiling and a little surprised that he had asked my permission. No one else had that evening.

Thanking me, he turned around towards the main door of the ward, located just beyond behind the nurses' station. Bowing to the rabbi who was just out of sight, the son addressed him in the third person: "Please, may the honorable rabbi enter." After kissing the rabbi's hand, he straightened up and led the guest to his father's room.

I followed them down the hall with my eyes. It was only as they were about to enter the room that I noticed that the rabbi was carrying a white chicken in his arms. Although quiet, the chicken was very much alive.

Amazed, I stood up and followed them into the room. Inside, there were perhaps 20 people, the men standing in a tight circle around my patient's bed, the women sitting off to the side. The rabbi, who I suspected would be visiting other patients that evening, had already begun to chant the prayer for the recovery of the sick, one that I recognized. Totally new for me, however, was the role of the chicken. Clasped snugly in the rabbi's hands, the bird was being waved in tight circles about 12 inches above the patient's head as the prayer was being chanted. I was familiar with the practice of kaparot, in which observant Jews swing a live chicken over their heads on the day before Yom Kippur to symbolize the casting away of sin. I had never, however, seen or heard of this being done as part of a Jewish healing ceremony.

My patient's eyes were partially closed, but the rest of the men by the bedside were fully engaged in ritual. Swaying back and forth, some chanted along with the rabbi. Only one person seemed to notice me as I entered the room. He glanced at me in a stern way, as if warning me not to interfere. I stayed there for a minute until one of the nurses called me away to see another patient.

A couple days later, I asked the son about the ritual I had witnessed. They were members of the local Persian-Jewish community, he explained, and this particular way of reciting the prayer for the sick — with the chicken — was their custom. Be'ezrat hashem (with God's help), his father would make a full recovery.

I was very impressed by how deftly the son was able to maneuver between two very different belief systems explaining his father's disease and paths towards possible recovery: biomedical and religious. As evidenced from our repeated discussions about tests and treatment plans for his father, he clearly understood — and valued — what modern medicine could offer. And yet, his belief in Divine mercy and intercession was unshakeable.

In her book "The Spirit Catches You and You Fall Down," Anne Fadiman describes the collision between two radically different belief systems, shamanism and biomedicine, held by the parents of a Hmong girl suffering from epilepsy and the physicians caring for her. The pushback the parents encountered from the medical team when they tried to incorporate shamanistic healing into their daughter's treatment plan led them to reject biomedicine altogether, with tragic consequences.

Although it hadn't occurred to me to disrupt the unfamiliar ceremony with the chicken — mostly because I was so astonished by it — I probably would have been within my rights to do so: bringing live poultry into an inpatient ward is risky from an infection-control perspective, after all.

I'm glad that I didn't. Doing so would have prevented my patient and his caregivers from accessing the healing potential that their religious beliefs provided them, and likely would have provoked antagonism towards — or the outright rejection of — the biomedicine that I represented. And that would have been detrimental to my patient, who so clearly needed the powers of both in order to heal.

Although nearly 19 years have passed since that October evening, hardly a month goes by in which I do not find myself reflecting on this patient, and the chicken. This invariably occurs because of an interaction I'm having with another patient or family with deeply held beliefs that need not only to be recognized and respected, but also integrated into the therapeutic approach in order for treatment to succeed. It is a lesson that has served me well, and which has helped me to serve so many others over the years.

---

Dennis Rosen, a pediatric pulmonologist practicing in Boston, is the author of "Vital Conversations: Improving Communication Between Doctors And Patients" (Columbia University Press).

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Well: Is Exercise Bad for Your Teeth?

Photo Credit Getty Images

Phys Ed

Gretchen Reynolds on the science of fitness.

Vigorous exercise is good for almost all of the body — except perhaps the teeth, according to a surprising new study of athletes. The study, published in The Scandinavian Journal of Medicine & Science in Sports, found that heavy training may contribute to dental problems in unexpected ways.

There have been hints in the past that athletes could have a heightened risk for cavities and other oral issues. In a study published last year in The British Journal of Sports Medicine, dentists who examined 278 athletes at the 2012 Summer Olympics in London reported that a majority displayed "poor oral health," including high levels of tooth decay, often in conjunction with gum disease and erosion of the tooth enamel. The athletes came from the United States and Europe as well as less-developed parts of the world, and most had access to good-quality dentistry, although many had not visited a dentist in the last year.

The study didn't examine why the athletes were at such high risk of dental problems, although many of us might assume that sugary sports drinks and bars would be a primary cause. Other studies, however, have found little if any link between consuming sports drinks and developing cavities.

So to better understand what is going on inside the mouths of athletes, researchers with the dental school at University Hospital Heidelberg in Germany and other institutions recruited 35 competitive triathletes and 35 age- and gender-matched healthy adults who were not athletes.

All of the volunteers visited the hospital's dental lab for a full oral examination, including collection of their saliva after they had been sitting quietly. They also completed questionnaires about their diets, including consumption of sports drinks and other beverages, their normal oral hygiene routines, and their exercise habits, if any.

Fifteen of the athletes also completed an increasingly strenuous run of about 35 minutes on an outdoor track, during which their saliva was collected several times.

Then the researchers compared the groups' teeth and spit, which turned out to be different in telling ways.

Compared with the control group, the athletes showed significantly greater erosion of their tooth enamel. They also tended to have more cavities, with the risk increasing as an athlete's training time grew. Over all, the more hours that an athlete spent working out, the more likely he or she was to have cavities.

The researchers found no correlation, however, between consuming sports drinks or any other elements of the athletes' diets and their oral health.

They also found no differences in the amount or chemical make-up of their volunteers' saliva after the athletes and the non-athletes had been at rest.

But that situation changed when the athletes worked out. During their experimental runs, the amount of saliva that they produced progressively lessened, meaning that their mouths became drier, regardless of whether they consumed water or other beverages during the workout. The saliva's chemical composition also shifted, growing more alkaline as the workout continued. Excess alkalinity in saliva is thought to contribute to the development of tartar plaques on teeth and other problems.

The extent of the changes in the athletes' saliva during a workout were something of a surprise, said Dr. Cornelia Frese, a senior dentist at University Hospital Heidelberg, who led the study.

"We had thought sports drinks and nutrition might have the most detrimental influence on dental decay," she said, "but we saw no direct link" between them. Instead, it was the changes in saliva during exercise that differentiated the athletes' mouths from those of the control group. Since saliva "has a very protective function" for teeth, Dr. Frese said, having less of it or a chemically different version during exercise could be problematic.

But, she cautions, this study was small, short-term and in many ways unrepresentative of the oral risks most of us would likely face from exercise. "The athletes participating in our study had a mean weekly training time of nine hours," she said. They were, in technical parlance, hard-core.

"All we can say" based on the data from this group, she said, "is that prolonged endurance training might be a risk factor for oral health." Whether less frequent or intense exercise would likewise affect oral health is uncertain but unlikely, Dr. Frese said.

Still there are a few precautions that anyone who exercises and has concerns about their oral health might want to take, she said. Drinking water during workouts could be a start, although the connection between hydration and oral health is not scientifically established, Dr. Frese said. More generally, brush and floss, as you know you should. And if you're a serious endurance athlete, consider visiting a dentist with a specialty in sports dentistry, she said. The goal is to ensure that your teeth remain in as good shape as the rest of you.

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Well: A Better Baby I.C.U.

By many measures, a neonatal intensive care unit, or NICU, with single-family rooms produces better results than one with a shared, open-bay arrangement, a new study has found.

Researchers tracked outcomes in an open-bay NICU for 18 months before the unit was moved to a new single-family room facility. Then they tracked successive admissions to the new facility and compared them with the open-bay NICU results.

There were no differences between the 151 infants in either type of intensive care unit in terms of gestational age at birth, race or maternal educational status or ethnicity. But the study, published in Pediatrics, found significant differences in medical outcomes.

Infants in the single-family rooms weighed more at discharge and gained weight more rapidly. They needed fewer medical procedures, had increased attention, less stress, less lethargy and less pain.

"In a room, you have privacy, the lighting you want, nurses who work one-on-one with the moms. It's relaxed, it's calm," said the lead author, Barry M. Lester, director of the Brown Center for the Study of Children at Risk at Women and Infants Hospital of Rhode Island. "There's more maternal involvement than in the open bay and more maternal involvement leads to better behavioral and medical outcomes."

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Well: Artificial Sweeteners May Disrupt Body’s Blood Sugar Controls

Photo Researchers say gut bacteria changed in subjects that consumed artificial sweeteners, leading to glucose intolerance.Credit Weizmann Institute of Science

Artificial sweeteners may disrupt the body's ability to regulate blood sugar, causing metabolic changes that can be a precursor to diabetes, researchers are reporting.

That is "the very same condition that we often aim to prevent" by consuming sweeteners instead of sugar, said Dr. Eran Elinav, an immunologist at the Weizmann Institute of Science in Israel, at a news conference to discuss the findings.

The scientists performed a multitude of experiments, mostly on mice, to back up their assertion that the sweeteners alter the microbiome, the population of bacteria that is in the digestive system.

The different mix of microbes, the researchers contend, changes the metabolism of glucose, causing levels to rise higher after eating and to decline more slowly than they otherwise would.

The findings by Dr. Elinav and his collaborators in Israel, including Eran Segal, a professor of computer science and applied mathematics at Weizmann, are being published Wednesday by the journal Nature.

Cathryn R. Nagler, a professor of pathology at the University of Chicago who was not involved with the research but did write an accompanying commentary in Nature, called the results "very compelling."

She noted that many conditions, including obesity and diabetes, had been linked to changes in the microbiome. "What the study suggests," she said, "is we should step back and reassess our extensive use of artificial sweeteners."

Previous studies on the health effects of artificial sweeteners have come to conflicting and confusing findings. Some found that they were associated with weight loss; others found the exact opposite, that people who drank diet soda actually weighed more.

Some found a correlation between artificial sweeteners and diabetes, but those findings were not entirely convincing: Those who switch to the products may already be overweight and prone to the disease.

While acknowledging that it is too early for broad or definitive conclusions, Dr. Elinav said he had already changed his own behavior.

"I've consumed very large amounts of coffee, and extensively used sweeteners, thinking like many other people that they are at least not harmful to me and perhaps even beneficial," he said. "Given the surprising results that we got in our study, I made a personal preference to stop using them.

"We don't think the body of evidence that we present in humans is sufficient to change the current recommendations," he continued. "But I would hope it would provoke a healthy discussion."

In the initial set of experiments, the scientists added saccharin (the sweetener in the pink packets of Sweet'N Low), sucralose (the yellow packets of Splenda) or aspartame (the blue packets of Equal) to the drinking water of 10-week-old mice. Other mice drank plain water or water supplemented with glucose or with ordinary table sugar. After a week, there was little change in the mice that drank water or sugar water, but the group getting artificial sweeteners developed marked intolerance to glucose.

Glucose intolerance, in which the body is less able to cope with large amounts of sugar, can lead to more serious illnesses like metabolic syndrome and Type 2 diabetes.

When the researchers treated the mice with antibiotics, killing much of the bacteria in the digestive system, the glucose intolerance went away.

At present, the scientists cannot explain how the sweeteners affect the bacteria or why the three different molecules of saccharin, aspartame and sucralose result in similar changes in the glucose metabolism.

To further test their hypothesis that the change in glucose metabolism was caused by a change in bacteria, they performed another series of experiments, this time focusing just on saccharin. They took intestinal bacteria from mice who had drank saccharin-laced water and injected them in mice that had never been exposed any saccharin. Those mice developed the same glucose intolerance. And DNA sequencing showed that saccharin had markedly changed the variety of bacteria in the guts of the mice that consumed it.

Next, the researchers turned to a study they were conducting to track the effects of nutrition and gut bacteria on people's long-term health. For 381 nondiabetic participants in the study, the researchers found a correlation between the reported use of any kind of artificial sweeteners and signs of glucose intolerance. In addition, the gut bacteria of those who used artificial sweeteners were different from those who did not.

Finally, they recruited seven volunteers who normally did not use artificial sweeteners and over six days gave them the maximum amount of saccharin recommended by the United States Food and Drug Administration. In four of the seven, blood-sugar levels were disrupted in the same way as in mice.

Further, when they injected the human participants' bacteria into the intestines of mice, the animals again developed glucose intolerance, suggesting that effect was the same in both mice and humans.

"That experiment is compelling to me," Dr. Nagler said.

Intriguingly — "superstriking and interesting to us," Dr. Segal said — the intestinal bacteria of the people who did experience effects were different from those who did not. This suggests that any effects of artificial sweeteners are not universal. It also suggests probiotics — medicines consisting of live bacteria — could be used to shift gut bacteria to a population that reversed the glucose intolerance.

Dr. Frank Hu, a professor of nutrition and epidemiology at the Harvard School of Public Health who did not take part in the study, called it interesting but far from conclusive and added that given the number of participants, "I think the validity of the human study is questionable."

The researchers said future research would examine aspartame and sucralose in detail as well as other alternative sweeteners like stevia.

Correction: September 20, 2014
An article Thursday about the effect of artificial sweeteners on metabolism misstated the title of a researcher who commented on the study. Dr. Frank Hu is a professor of nutrition and epidemiology, not immunology, at the Harvard School of Public Health.

A version of this article appears in print on 09/18/2014, on page A4 of the NewYork edition with the headline: Artificial Sweeteners Alter Metabolism, Study Finds.

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DealBook: Bayer to Spin Off Plastics Group to Focus on Health Care

Photo A Bayer plant in Leverkusen, Germany. Though it started as a chemical company, Bayer now makes nearly half its revenue from its health care business.Credit Ina Fassbender/Reuters

Updated, 7:42 p.m. | The German drug maker Bayer said on Thursday that it planned to spin off its polymer business into a new, publicly listed entity as the company moves to shift its focus primarily to health care.

Bayer started in Germany in 1863 as a chemical company making dyes for the textile industry, but now generates nearly half of its sales from its health care business. Among the company's best-known products is its aspirin.

The plan to spin off the polymer business, known as Bayer MaterialScience, was approved by Bayer's management board early this month and by its supervisory board in a unanimous vote on Thursday. Bayer's health care products are part of its life sciences group, which also includes its crop science division. The crop unit, which Bayer will be retaining, focuses on chemical and biological products like insecticides and plant seeds.

"Our intention is to create two top global corporations: Bayer as a world-class innovation company in the life science businesses, and MaterialScience as a leading player in polymers," Marijn Dekkers, the Bayer chief executive, said in a statement on Thursday.

Credit Oliver Berg/European Pressphoto Agency

Bayer said it planned to list the material science business as a separate company in the next 12 to 18 months.

"A major reason for this move is to give MaterialScience direct access to capital for its future development," Bayer said in its statement. "This access can no longer be adequately ensured within the Bayer Group due to the substantial investment needs of the life science businesses for both organic and external growth."

The separation also will allow the polymer business to better align its organization and structure for the industries it serves, the company said.

In recent years, Bayer has been shifting more of its focus and resources to its life science group, which accounted for over 70 percent of its sales last year. In May, Bayer agreed to pay $14.2 billion for Merck's consumer care business, which will bring it the allergy medicine Claritin, the foot care brand Dr. Scholl's and Coppertone sunscreen. The deal will make Bayer one of the largest providers of over-the-counter health care products.

Bayer's core health care business alone generated 18.9 billion euros, or about $24.5 billion, in sales in 2013. It employs 56,000 people, nearly half of the company's work force. Over all, Bayer posted sales of about €40.2 billion in 2013 and had about 113,200 employees.

Photo Marijn Dekkers, C.E.O., said both units would remain industry leaders.Credit Rolf Vennenbernd/European Pressphoto Agency

The life science businesses together had sales of about €29 billion last year and employ nearly 99,000 people, about 29,500 of them in Germany. Bayer and the spun-off plastics business will continue to be based in Leverkusen, Germany. The spinoff will adopt a new name.

The material science business was split off as its own division within Bayer in 2004, but traces its roots to the beginning of the 20th century. One of its scientists, Fritz Hofmann, helped create the first synthetic rubber. Its plastics and coatings are used in passenger and commercial vehicles, CDs and DVDs and in the construction industry.

The material science business had sales of €11.2 billion in 2013, accounting for just under a third of Bayer's sales. After the split, it will employ about 16,800 people worldwide, including about 6,500 in Germany.

The Wall Street Journal, citing sources, reported on Wednesday that Bayer planned to spin off the polymers unit.

A version of this article appears in print on 09/19/2014, on page B5 of the NewYork edition with the headline: Bayer Will Spin Off Plastics Group to Focus on Health Care .

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Well: Artificial Sweeteners May Disrupt Body’s Blood Sugar Controls

Photo Sweeteners alter the microbiome, the population of bacteria that is in the digestive system.Credit Weizmann Institute of Science

Artificial sweeteners may disrupt the body's ability to regulate blood sugar, causing metabolic changes that can be a precursor to diabetes, researchers are reporting.

That is "the very same condition that we often aim to prevent" by consuming sweeteners instead of sugar, said Dr. Eran Elinav, an immunologist at the Weizmann Institute of Science in Israel, at a news conference to discuss the findings.

The scientists performed a multitude of experiments, mostly on mice, to back up their assertion that the sweeteners alter the microbiome, the population of bacteria that is in the digestive system.

The different mix of microbes, the researchers contend, changes the metabolism of glucose, causing levels to rise higher after eating and to decline more slowly than they otherwise would.

The findings by Dr. Elinav and his collaborators in Israel, including Eran Segal, a professor of computer science and applied mathematics at Weizmann, are being published Wednesday by the journal Nature.

Cathryn R. Nagler, a professor of pathology at the University of Chicago who was not involved with the research but did write an accompanying commentary in Nature, called the results "very compelling."

She noted that many conditions, including obesity and diabetes, had been linked to changes in the microbiome. "What the study suggests," she said, "is we should step back and reassess our extensive use of artificial sweeteners."

Previous studies on the health effects of artificial sweeteners have come to conflicting and confusing findings. Some found that they were associated with weight loss; others found the exact opposite, that people who drank diet soda actually weighed more.

Some found a correlation between artificial sweeteners and diabetes, but those findings were not entirely convincing: Those who switch to the products may already be overweight and prone to the disease.

While acknowledging that it is too early for broad or definitive conclusions, Dr. Elinav said he had already changed his own behavior.

"I've consumed very large amounts of coffee, and extensively used sweeteners, thinking like many other people that they are at least not harmful to me and perhaps even beneficial," he said. "Given the surprising results that we got in our study, I made a personal preference to stop using them.

"We don't think the body of evidence that we present in humans is sufficient to change the current recommendations," he continued. "But I would hope it would provoke a healthy discussion."

In the initial set of experiments, the scientists added saccharin (the sweetener in the pink packets of Sweet'N Low), sucralose (the yellow packets of Splenda) or aspartame (the blue packets of Equal) to the drinking water of 10-week-old mice. Other mice drank plain water or water supplemented with glucose or with ordinary table sugar. After a week, there was little change in the mice who drank water or sugar water, but the group getting artificial sweeteners developed marked intolerance to glucose.

Glucose intolerance, in which the body is less able to cope with large amounts of sugar, can lead to more serious illnesses like metabolic syndrome and Type 2 diabetes.

When the researchers treated the mice with antibiotics, killing much of the bacteria in the digestive system, the glucose intolerance went away.

At present, the scientists cannot explain how the sweeteners affect the bacteria or why the three different molecules of saccharin, aspartame and sucralose result in similar changes in the glucose metabolism.

To further test their hypothesis that the change in glucose metabolism was caused by a change in bacteria, they performed another series of experiments, this time focusing just on saccharin. They took intestinal bacteria from mice who had drank saccharin-laced water and injected them in mice that had never been exposed any saccharin. Those mice developed the same glucose intolerance. And DNA sequencing showed that saccharin had markedly changed the variety of bacteria in the guts of the mice that consumed it.

Next, the researchers turned to a study they were conducting to track the effects of nutrition and gut bacteria on people's long-term health. For 381 nondiabetic participants in the study, the researchers found a correlation between the reported use of any kind of artificial sweeteners and signs of glucose intolerance. In addition, the gut bacteria of those who used artificial sweeteners were different from those who did not.

Finally, they recruited seven volunteers who normally did not use artificial sweeteners and over six days gave them the maximum amount of saccharin recommended by the United States Food and Drug Administration. In four of the seven, blood-sugar levels were disrupted in the same way as in mice.

Further, when they injected the human participants' bacteria into the intestines of mice, the animals again developed glucose intolerance, suggesting that effect was the same in both mice and humans.

"That experiment is compelling to me," Dr. Nagler said.

Intriguingly — "superstriking and interesting to us," Dr. Segal said — the intestinal bacteria of the people who did experience effects were different from those who did not. This suggests that any effects of artificial sweeteners are not universal. It also suggests probiotics — medicines consisting of live bacteria — could be used to shift gut bacteria to a population that reversed the glucose intolerance.

Dr. Frank Hu, a professor of nutrition and immunology at the Harvard School of Public Health who did not take part in the study, called it interesting but far from conclusive and added that given the number of participants, "I think the validity of the human study is questionable."

The researchers said future research would examine aspartame and sucralose in detail as well as other alternative sweeteners like stevia.

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Phys Ed: Sit Less, Live Longer?

Photo Credit Getty Images

Phys Ed

Gretchen Reynolds on the science of fitness.

If people need motivation to get up from their office chairs or couches and become less sedentary, two useful new studies could provide the impetus. One found that sitting less can slow the aging process within cells, and the other helpfully underscores that standing up — even if you are standing still — can be good for you as well.

For most of us nowadays, sitting is our most common waking activity, with many of us sitting for eight hours or more every day. Even people who exercise for an hour or so tend to spend most of the remaining hours of the day in a chair.

The health consequences of this sedentariness are well-documented. Past studies have found that the more hours that people spend sitting, the more likely they are to develop diabetes, heart disease and other conditions, and potentially to die prematurely — even if they exercise regularly.

But most of these studies were associational, meaning that they found a link between sitting and illness, but could not prove whether or how sitting actually causes ill health.

So for the most groundbreaking of the new studies, which was published this month in the British Journal of Sports Medicine, scientists in Sweden decided to mount an actual experiment, in which they would alter the amount of time that people spent exercising and sitting, and track certain physiological results. In particular, with this experiment, the scientists were interested in whether changes in sedentary time would affect people's telomeres.

If you are unfamiliar with the componentry of your genes, telomeres are the tiny caps on the ends of DNA strands. They shorten and fray as a cell ages, although the process is not strictly chronological. Obesity, illness and other conditions can accelerate the shortening, causing cells to age prematurely, while some evidence suggests that healthy lifestyles may preserve telomere length, delaying cell aging.

For the new experiment, the Swedish scientists recruited a group of sedentary, overweight men and women, all aged 68, and drew blood, in order to measure the length of telomeres in the volunteers' white blood cells. Then half of the volunteers began an individualized, moderate exercise program, designed to improve their general health. They also were advised to sit less.

The other volunteers were told to continue with their normal lives, although the scientists urged them to try to lose weight and be healthy, without offering any specific methods.

After six months, the volunteers all returned for a second blood draw and to complete questionnaires about their daily activities. These showed that those in the exercise group were, not surprisingly, exercising more than they had been previously. But they were also, for the most part, sitting substantially less than before.

And when the scientists compared telomeres, they found that the telomeres in the volunteers who were sitting the least had lengthened. Their cells seemed to be growing physiologically younger.

Meanwhile, in the control group telomeres generally were shorter than they had been six months before.

But perhaps most interesting, there was little correlation between exercise and telomere length. In fact, the volunteers in the exercise group who had worked out the most during the past six months tended now to have slightly less lengthening and even some shortening, compared to those who had exercised less but stood up more.

Reducing sedentary time had lengthened telomeres, the scientists concluded, while exercising had played little role.

Exactly what the volunteers did in lieu of sitting is impossible to say with precision, said Per Sjögren, a professor of public health at Uppsala University in Sweden, who led the study, because the researchers did not track their volunteers' movement patterns with monitors. But "it's most likely," he said, that "sitting time was predominantly replaced with low-intensity activities," and in particular with time spent standing up.

Which makes the second new study of sedentary behavior particularly relevant. Standing is not, after all, physically demanding for most people, and some scientists have questioned whether merely standing up — without also moving about and walking — is sufficiently healthy or if standing merely replaces one type of sedentariness with another.

If so, standing could be expected to increase health problems and premature death, as sitting has been shown to do.

To find out whether that situation held true, Peter Katzmarzyk, a professor of public health at the Pennington Biomedical Research Center in Baton Rouge, La., and an expert on sedentary behavior, turned to a large database of self-reported information about physical activity among Canadian adults. He noted the amount of time that the men and women had reported standing on most days over the course of a decade or more and crosschecked that data with death records, to see whether people who stood more died younger.

The results, published in May in Medicine & Science in Sports & Exercise, are soothing if predictable. Dr. Katzmarzyk found no link between standing and premature death. Rather, as he writes in the study, "mortality rates declined at higher levels of standing," suggesting that standing is not sedentary or hazardous, a conclusion with which our telomeres would likely concur.

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The New Old Age: On New Measurements of Aging

Pediatricians chart children's growth at every visit, tracking how they conform to age-appropriate standards. What if standard measures of aging were similarly available?

Warren Sanderson, a professor of social and behavioral sciences at Stony Brook University, is working on ways to define aging other than the passing of years. With colleagues at the International Institute for Applied Systems Analysis in Laxenburg, Austria, he recently published a study showing that the strength of an adult's hand grip can distinguish different rates of aging in people with varying levels of education. The conversation below has been condensed and edited for space and clarity.

Your work over the past several years suggests that the conventional definition of old age — as beginning at age 65 — is outdated. Why?

Life expectancy has changed. Disability rates have changed. Health status has changed. Everything is changing about 65-year-olds. They're not the same as they were in 1950 or as they will be in 2050. Still, conventional measures used across the world treat everyone as becoming old starting at age 65. That distorts our view of aging and public policies related to aging.

How should we think about the onset of older age?

We should consider people as old when they near the end of their life: when their remaining life expectancy is 15 years or less. Let's take two 65-year-olds. Say one has a remaining life expectancy of five years. One has a remaining life expectancy of 25 years. Which one is aging faster?

We would say the first one, because she's so much closer to the end of her life. The second one is still far from the end of her life. She's effectively younger.

What would this mean in the United States?

In 2010, if you used our definition, men would start being classified as "old" when they reached the age of 69.2 years old and women when they reached the age of 72.3 years old.

You've proposed what you call a "characteristics" approach to evaluating aging. What does this entail?

We think age has much more to do with how people function than how many birthdays they've had, so measuring function is the crucial thing. Our research agenda calls for looking at different measures of functioning because aging is multidimensional. We started with hand-grip strength, a measure of upper-body strength.

Why did you begin there?

Hand-grip strength is an amazingly good predictor of future rates of mortality and morbidity, or sickness. It's been measured for individuals in surveys across the world. We now have comparable data on about 50,000 people from the U.S., many European countries, Japan, South Korea, China. A substantial body of research suggests that this can be used as a reliable predictor of aging.

Tell me about the study you just published.

We know there are important differences in the U.S. in life expectancy among groups with different levels of education. We decided to compare men and women with low education — those who never graduated from high school — with those with higher education. We wanted to compare them in terms of how rapidly they were aging based on their hand grips.

What did you find?

A 65-year-old white woman with low education had the same hand-grip strength as a 69.5-year-old white woman with more education. The woman with low education had an age disadvantage of about 4.5 years. She was more like an old person than the woman with higher education.

For a 65-year-old white man, the difference was 4.6 years. For African-American women, the more educated women had a 3.5-year advantage. For African-American men, there was no difference between people with low and higher education. We don't understand that finding, but we think it's interesting and something we need to follow up on.

What are the implications?

Measuring hand-grip strength is very simple and cheap. We think every primary care doctor should have a dynamometer in their office. At every visit, the doctor could check grip strength for older patients. If someone was in the 45th percentile for their age and the measurements were stable, great. But if that person suddenly dropped to the 25th percentile, then that's a sign that the doctor should look seriously at what might be going on.

We view this in a larger context. There are going to be more measures than this one. We want to look next at measures of lower-body strength. It may very well be a measure that looks at how long it takes someone to rise from a chair. Then, we will have an upper-body measure and a lower-body measure, and we can compare the two in terms of how aging goes. We envision one day that physicians will have standard age-related tables for these measures and chart their patients' progress, just as they do with height and weight for children.

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Well: Select Drugs Cause Most Childhood Poisonings

Almost all prescription medicines in the United States come in bottles with child-resistant caps. Still, more than 9,000 children younger than 6 are hospitalized annually for the accidental ingestion of prescription drugs; three-quarters of these are 1- and 2-year-olds, a new study reports.

Twelve active ingredients were involved in almost half of hospitalizations of children for prescription drug poisoning, the researchers found. The most often implicated medicines contained buprenorphine, used for treating narcotic addiction and sometimes as a pain reliever; and clonidine, a substance in medicines for high blood pressure, attention-deficit hyperactivity disorder and migraines, among other ailments.

Opioid pain relievers like Vicodin and antianxiety drugs like Valium and Xanax accounted for about 28 percent of hospitalizations.

The scientists used data from a surveillance system maintained by the Consumer Product Safety Commission and controlled for the number of prescriptions issued. The findings were published in Pediatrics.

"Individually packaged pills might be one way to make these products safer," said the senior author, Dr. Daniel S. Budnitz, the director of the Medication Safety Program at the Centers for Disease Control and Prevention. But, he added, "the message now to caregivers is to keep medicines up and out of sight of children, especially immediately after use."

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The New Old Age: Tougher Than They Look

Photo Credit Getty Images

Resilience, the subject of a large-scale study published recently in The Gerontologist, reminds me of what a Supreme Court justice once said of pornography: It's hard to define, but we know it when we see it.

We've all noticed resilience's effects, haven't we? Most older people cope with several chronic diseases and have encountered losses and challenges. Some seem to withdraw into isolation and inactivity even when they remain relatively strong.

Others respond more like the late Evelyn Nade, whom I met in a New Jersey nursing home a few years ago. She was 82 then, a wheelchair user who couldn't rise from her bed without two aides using a mechanical hoist — yet she was the sunniest person in the place, the president of the residents' council, the founder of a Red Hat Society chapter and a formidable poker player.

Age, health and finances can't fully explain such disparities, so social scientists are constantly exploring other factors that might play a role.

When I spoke with the new study's lead author, Lydia Manning, a gerontologist at Concordia University Chicago, she took a stab at a simple definition of resilience: "How people manage adversity and hardship over the life course." Often, she said, they talk about learning this trait, this sense of themselves as people who can negotiate obstacles, from tough experiences earlier in life.

Scientists have been writing and thinking about resilience for several decades. Now, in Dr. Manning's study of 10,753 people (average age: almost 69) drawn from three waves of the national Health and Retirement Study, "we're starting to measure it," Dr. Manning said — "as squishy and fuzzy a concept as it is."

To do that, the team devised and validated a simplified scale of 12 items, based on how strongly subjects agreed or disagreed with statements like: "When I really want to do something, I usually find a way to succeed at it," and "I have a sense of direction and purpose in life." Also included were statements like, "If something can go wrong for me, it will," and "There is really no way I can solve the problems I have."

Over two years, 11 percent of this sample developed a new chronic condition: heart or lung disease, stroke, psychiatric problems, cancer.

These can be devastating. Yet the higher people scored on the resilience scale, the less likely this new obstacle was to disable them.

The researchers looked at their subjects' subsequent ability to perform "activities of daily living," like bathing and dressing, and to handle "instrumental activities of daily living" like using a phone and making meals.

Dr. Manning and her colleagues tried to account for the participants' actual health, including depression, and for sociodemographic differences. The researchers found that when a new disease struck, the least resilient had on average nearly triple the amount of activities of daily living disabilities, compared to the most resilient.

Resilience provided what researchers called a "moderating effect." The extent of disability among this relatively young population was already low: Among those facing a new illness, the least resilient subsequently experienced on average only one A.D.L. disability. But the most resilient were on average barely disabled at all by a new illness.

"You throw something at them, something bad — a new chronic condition is really hard — and we see this bounce-back pretty rapidly," said the co-author Dawn Carr, a gerontologist at the Stanford Center on Longevity. "They're able to maintain their function."

How this works is a question this study can't answer. But Dr. Manning points out that people often describe resilience as acquired, during "moments of adversity."

So perhaps other people can acquire it, too, even late in life. "What strategies would help people bolster their resilience?" she said, envisioning "resilience interventions" in the future. "I believe that unlike some concepts — where you either have it or you don't, you're resilient or you're vulnerable — everybody has the capacity for resilience."

Confession: I'm neither a religious nor a "spiritual" person, and much of the positive-attitude talk we constantly hear strikes me as malarkey. Sometimes, what doesn't kill you makes you weaker. And yet. …

I've reported here on evidence that a sense of purpose correlates with lower rates of Alzheimer's disease and that volunteering in schools is linked to improved cognitive function.

I've come across a couple of recent studies on the impact of religiosity. Even "nonorganizational forms" appear to protect against depression or help people recover from it, and religious attendance is associated with lower levels of certain physiological problems.

Self-efficacy, mastery, gratitude — they're amorphous concepts, but researchers are finding that they can have real-world effects. As we all wait to learn more, it's clear that a healthy old age, however defined, involves more than excellent blood pressure.

Something else is going on. "It is slippery stuff," Dr. Manning acknowledged. "I find it fascinating."

Paula Span is the author of "When the Time Comes: Families With Aging Parents Share Their Struggles and Solutions."

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Well: Training Dogs to Sniff Out Cancer

Photo McBaine, a cancer detection dog.Credit Penn Vet Working Dog Center

PHILADELPHIA — McBaine, a bouncy black and white springer spaniel, perks up and begins his hunt at the Penn Vet Working Dog Center. His nose skims 12 tiny arms that protrude from the edges of a table-size wheel, each holding samples of blood plasma, only one of which is spiked with a drop of cancerous tissue.

The dog makes one focused revolution around the wheel before halting, steely-eyed and confident, in front of sample No. 11. A trainer tosses him his reward, a tennis ball, which he giddily chases around the room, sliding across the floor and bumping into walls like a clumsy puppy.

McBaine is one of four highly trained cancer detection dogs at the center, which trains purebreds to put their superior sense of smell to work in search of the early signs of ovarian cancer. Now, Penn Vet, part of the University of Pennsylvania's School of Veterinary Medicine, is teaming with chemists and physicists to isolate cancer chemicals that only dogs can smell. They hope this will lead to the manufacture of nanotechnology sensors that are capable of detecting bits of cancerous tissue 1/100,000th the thickness of a sheet of paper.

"We don't ever anticipate our dogs walking through a clinic," said the veterinarian Dr. Cindy Otto, the founder and executive director of the Working Dog Center. "But we do hope that they will help refine chemical and nanosensing techniques for cancer detection."

Since 2004, research has begun to accumulate suggesting that dogs may be able to smell the subtle chemical differences between healthy and cancerous tissue, including bladder cancer, melanoma and cancers of the lung, breast and prostate. But scientists debate whether the research will result in useful medical applications.

Photo Trainers tend to notice early on that certain dogs have natural talents that make them better suited for specific kinds of work.Credit Penn Vet Working Dog Center.

Dogs have already been trained to respond to diabetic emergencies, or alert passers-by if an owner is about to have a seizure. And on the cancer front, nonprofit organizations like the In Situ Foundation, based in California, and the Medical Detection Dogs charity in Britain are among a growing number of independent groups sponsoring research into the area.

A study presented at the American Urological Association's annual meeting in May reported that two German shepherds trained at the Italian Ministry of Defense's Military Veterinary Center in Grosseto were able to detect prostate cancer in urine with about 98 percent accuracy, far better than the prostate-specific antigen (PSA) test. But in another recent study of prostate-cancer-sniffing dogs, British researchers reported that promising initial results did not hold up in rigorous double-blind follow-up trials.

Dr. Otto first conceived of a center to train and study working dogs when, as a member of the Federal Emergency Management Agency's Urban Search and Rescue Team, she was deployed to ground zero in the hours after the Sept. 11 attacks.

"I remember walking past three firemen sitting on an I-beam, stone-faced, dejected," she says. "But when a handler walked by with one of the rescue dogs, they lit up. There was hope."

Today, the Working Dog Center trains dogs for police work, search and rescue and bomb detection. Their newest canine curriculum, started last summer after the center received a grant from the Kaleidoscope of Hope Foundation, focuses on sniffing out a different kind of threat: ovarian cancer.

"Ovarian cancer is a silent killer," Dr. Otto said. "But if we can help detect it early, that would save lives like nothing else."

Dr. Otto's dogs are descended from illustrious lines of hunting hounds and police dogs, with noses and instincts that have been refined by generations of selective breeding. Labradors and German shepherds dominate the center, but the occasional golden retriever or springer spaniel — like McBaine — manages to make the cut.

The dogs, raised in the homes of volunteer foster families, start with basic obedience classes when they are eight weeks old. They then begin their training in earnest, with the goal of teaching them that sniffing everything — from ticking bombs to malignant tumors — is rewarding.

"Everything we do is about positive reinforcement," Dr. Otto said. "Sniff the right odor, earn a toy or treat. It's all one big game."

Trainers from the center typically notice early on that certain dogs have natural talents that make them better suited for specific kinds of work. Search and rescue dogs must be tireless hunters, unperturbed by distracting environments and unwilling to give up on a scent – the equivalent of high-energy athletes. The best cancer-detection dogs, on the other hand, tend to be precise, methodical, quiet and even a bit aloof — more the introverted scientists.

"Some dogs declare early, but our late bloomers frequently switch majors," Dr. Otto said.

Handlers begin training dogs selected for cancer detection by holding two vials of fluid in front of each dog, one cancerous and one benign. The dogs initially sniff both but are rewarded only when they sniff the one containing cancer tissue. In time, the dogs learn to recognize a unique "cancer smell" before moving on to more complex tests.

What exactly are the dogs sensing? George Preti, a chemist at the Monell Chemical Senses Center in Philadelphia, has spent much of his career trying to isolate the volatile chemicals behind cancer's unique odor. "We have known for a long time that dogs are very sensitive detectors," Dr. Preti says. "When the opportunity arose to collaborate with Dr. Otto at the Working Dog Center, I jumped on it."

Dr. Preti is working to isolate unique chemical biomarkers responsible for ovarian cancer's subtle smell using high-tech spectrometers and chromatographs. Once he identifies a promising compound, he tests whether the dogs respond to that chemical in the same way that they respond to actual ovarian cancer tissue.

"I'm not embarrassed to say that a dog is better than my instruments," Dr. Preti says.

Photo The dogs, raised in the homes of volunteer foster families, begin their training at 8 weeks of age, starting with basic obedience classes.Credit Penn Vet Working Dog Center.

The next step will be to build a mechanical, hand-held sensor that can detect that cancer chemical in the clinic. That's where Charlie Johnson a professor at Penn who specializes in experimental nanophysics, the study of molecular interactions between microscopic materials, comes in.

He is developing what he calls Cyborg sensors, which include biological and mechanical components – a combination of carbon nanotubes and single-stranded DNA that preferentially bond with one specific chemical compound. These precise sensors, in theory, could be programmed to bind to, and detect, the isolated compounds that Dr. Otto's dogs are singling out.

"We are effectively building an electronic nose," said Dr. Johnson, who added that a prototype for his ovarian cancer sensor will probably be ready in the next five years.

Some experts remain skeptical.

"While I applaud any effort to detect ovarian cancer, I'm uncertain that this research will have any value," said Dr. David Fishman, a gynecologic oncologist at Mount Sinai Hospital in New York City. One challenge, he notes, is that any cancer sensor would need to be able to detect volatile chemicals that are specific to one particular type of cancer.

"Nonspecificity is where a lot of these sort of tests fail," Dr. Fishman said. "If there is an overlap in volatile chemicals — between colon, breast, pancreatic, ovarian cancer — we'll have to ask, 'What does this mean?' "

And even if sensors could be developed that detect ovarian cancer in the clinic, Dr. Fishman says, he doubts that they would be able to catch ovarian cancer in its earliest, potentially more treatable, stages.

"The lesions that we are discussing are only millimeters in size, and almost imperceptible on imaging studies," Dr. Fishman says. "I don't believe that the resolution of the canine ability will translate into value for these lesions."

McBaine remains unaware of the debate. After correctly identifying yet another cancerous plasma sample, he pranced around the Working Dog Center with regal flair, showing off his tennis ball to anyone who would pay attention. In an industry saturated with hundreds of corporations and thousands of scientists all hunting for the earliest clues to cancer, working dogs are just another set of (slightly furrier) researchers.

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Well: Training Dogs to Sniff Out Cancer

Photo McBaine, a cancer detection dog.Credit Penn Vet Working Dog Center

PHILADELPHIA — McBaine, a bouncy black and white springer spaniel, perks up and begins his hunt at the Penn Vet Working Dog Center. His nose skims 12 tiny arms that protrude from the edges of a table-size wheel, each holding samples of blood plasma, only one of which is spiked with a drop of cancerous tissue.

The dog makes one focused revolution around the wheel before halting, steely-eyed and confident, in front of sample No. 11. A trainer tosses him his reward, a tennis ball, which he giddily chases around the room, sliding across the floor and bumping into walls like a clumsy puppy.

McBaine is one of four highly trained cancer detection dogs at the center, which trains purebreds to put their superior sense of smell to work in search of the early signs of ovarian cancer. Now, Penn Vet, part of the University of Pennsylvania's School of Veterinary Medicine, is teaming with the university's chemistry and physics departments to isolate cancer chemicals that only dogs can smell. They hope this will lead to the manufacture of nanotechnology sensors that are capable of detecting bits of cancerous tissue 1/100,000th the thickness of a sheet of paper.

"We don't ever anticipate our dogs walking through a clinic," said the veterinarian Dr. Cindy Otto, the founder and executive director of the Working Dog Center. "But we do hope that they will help refine chemical and nanosensing techniques for cancer detection."

Since 2004, research has begun to accumulate suggesting that dogs may be able to smell the subtle chemical differences between healthy and cancerous tissue, including bladder cancer, melanoma and cancers of the lung, breast and prostate. But scientists debate whether the research will result in useful medical applications.

Photo Trainers tend to notice early on that certain dogs have natural talents that make them better suited for specific kinds of work.Credit Penn Vet Working Dog Center.

Dogs have already been trained to respond to diabetic emergencies, or alert passers-by if an owner is about to have a seizure. And on the cancer front, nonprofit organizations like the In Situ Foundation, based in California, and the Medical Detection Dogs charity in Britain are among a growing number of independent groups sponsoring research into the area.

A study presented at the American Urological Association's annual meeting in May reported that two German shepherds trained at the Italian Ministry of Defense's Military Veterinary Center in Grosseto were able to detect prostate cancer in urine with about 98 percent accuracy, far better than the prostate-specific antigen (PSA) test. But in another recent study of prostate-cancer-sniffing dogs, British researchers reported that promising initial results did not hold up in rigorous double-blind follow-up trials.

Dr. Otto first conceived of a center to train and study working dogs when, as a member of the Federal Emergency Management Agency's Urban Search and Rescue Team, she was deployed to ground zero in the hours after the Sept. 11 attacks.

"I remember walking past three firemen sitting on an I-beam, stone-faced, dejected," she says. "But when a handler walked by with one of the rescue dogs, they lit up. There was hope."

Today, the Working Dog Center trains dogs for police work, search and rescue and bomb detection. Their newest canine curriculum, started last summer after the center received a grant from the Kaleidoscope of Hope Foundation, focuses on sniffing out a different kind of threat: ovarian cancer.

"Ovarian cancer is a silent killer," Dr. Otto said. "But if we can help detect it early, that would save lives like nothing else."

Dr. Otto's dogs are descended from illustrious lines of hunting hounds and police dogs, with noses and instincts that have been refined by generations of selective breeding. Labradors and German shepherds dominate the center, but the occasional golden retriever or springer spaniel — like McBaine — manages to make the cut.

The dogs, raised in the homes of volunteer foster families, start with basic obedience classes when they are eight weeks old. They then begin their training in earnest, with the goal of teaching them that sniffing everything — from ticking bombs to malignant tumors — is rewarding.

"Everything we do is about positive reinforcement," Dr. Otto said. "Sniff the right odor, earn a toy or treat. It's all one big game."

Trainers from the center typically notice early on that certain dogs have natural talents that make them better suited for specific kinds of work. Search and rescue dogs must be tireless hunters, unperturbed by distracting environments and unwilling to give up on a scent – the equivalent of high-energy athletes. The best cancer-detection dogs, on the other hand, tend to be precise, methodical, quiet and even a bit aloof — more the introverted scientists.

"Some dogs declare early, but our late bloomers frequently switch majors," Dr. Otto said.

Handlers begin training dogs selected for cancer detection by holding two vials of fluid in front of each dog, one cancerous and one benign. The dogs initially sniff both but are rewarded only when they sniff the one containing cancer tissue. In time, the dogs learn to recognize a unique "cancer smell" before moving on to more complex tests.

What exactly are the dogs sensing? George Preti, a chemist at the Monell Chemical Senses Center in Philadelphia, has spent much of his career trying to isolate the volatile chemicals behind cancer's unique odor. "We have known for a long time that dogs are very sensitive detectors," Dr. Preti says. "When the opportunity arose to collaborate with Dr. Otto at the Working Dog Center, I jumped on it."

Dr. Preti is working to isolate unique chemical biomarkers responsible for ovarian cancer's subtle smell using high-tech spectrometers and chromatographs. Once he identifies a promising compound, he tests whether the dogs respond to that chemical in the same way that they respond to actual ovarian cancer tissue.

"I'm not embarrassed to say that a dog is better than my instruments," Dr. Preti says.

Photo The dogs, raised in the homes of volunteer foster families, begin their training at 8 weeks of age, starting with basic obedience classes.Credit Penn Vet Working Dog Center.

The next step will be to build a mechanical, hand-held sensor that can detect that cancer chemical in the clinic. That's where Charlie Johnson a professor at Penn who specializes in experimental nanophysics, the study of molecular interactions between microscopic materials, comes in.

He is developing what he calls Cyborg sensors, which include biological and mechanical components – a combination of carbon nanotubes and single-stranded DNA that preferentially bond with one specific chemical compound. These precise sensors, in theory, could be programmed to bind to, and detect, the isolated compounds that Dr. Otto's dogs are singling out.

"We are effectively building an electronic nose," said Dr. Johnson, who added that a prototype for his ovarian cancer sensor will probably be ready in the next five years.

Some experts remain skeptical.

"While I applaud any effort to detect ovarian cancer, I'm uncertain that this research will have any value," said Dr. David Fishman, a gynecologic oncologist at Mount Sinai Hospital in New York City. One challenge, he notes, is that any cancer sensor would need to be able to detect volatile chemicals that are specific to one particular type of cancer.

"Nonspecificity is where a lot of these sort of tests fail," Dr. Fishman said. "If there is an overlap in volatile chemicals — between colon, breast, pancreatic, ovarian cancer — we'll have to ask, 'What does this mean?' "

And even if sensors could be developed that detect ovarian cancer in the clinic, Dr. Fishman says, he doubts that they would be able to catch ovarian cancer in its earliest, potentially more treatable, stages.

"The lesions that we are discussing are only millimeters in size, and almost imperceptible on imaging studies," Dr. Fishman says. "I don't believe that the resolution of the canine ability will translate into value for these lesions."

McBaine remains unaware of the debate. After correctly identifying yet another cancerous plasma sample, he pranced around the Working Dog Center with regal flare, showing off his tennis ball to anyone who would pay attention. In an industry saturated with hundreds of corporations and thousands of scientists all hunting for the earliest clues to cancer, working dogs are just another set of (slightly furrier) researchers.

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Phys Ed: Drink Soda? Take 12,000 Steps

Photo Credit Getty Images

Phys Ed

Gretchen Reynolds on the science of fitness.

People who consume the sweetener fructose — which is most people nowadays — risk developing a variety of health problems. But the risk drops substantially if those people get up and move around, even if they don't formally exercise, two new studies found.

Most of us have heard that ingesting fructose, usually in the form of high-fructose corn syrup, is unhealthy, which few experts would dispute. High-fructose corn syrup is used to sweeten many processed foods and nearly all soft drinks.

The problem with the sweetener is that, unlike glucose, the formal name for common table sugar, fructose is metabolized primarily in the liver. There, much of the fructose is transformed into fatty acids, some of which remain in the liver, marbling that organ and contributing to nonalcoholic fatty liver disease.

The rest of the fatty acids migrate into the bloodstream, causing metabolic havoc. Past animal and human studies have linked the intake of even moderate amounts of fructose with dangerous gyrations in blood sugar levels, escalating insulin resistance, Type 2 diabetes, added fat around the middle, obesity, poor cholesterol profiles and other metabolic disruptions.

But Amy Bidwell, then a researcher at Syracuse University, noticed that few of these studies had examined interactions between physical activity and fructose. That was a critical omission, she thought, because movement and exercise change how the body utilizes fuels, including fructose.

Dr. Bidwell sought out healthy, college-aged men and women who would agree to drink soda in the pursuit of science. They were easy to find. She gathered 22.

The volunteers showed up at the university's physiology lab for a series of baseline tests. The researchers assessed how their bodies responded to a fructose-rich meal, recording their blood sugar and insulin levels, and other measures of general and metabolic health, including cholesterol profiles and blood markers of bodily inflammation. The students also completed questionnaires about their normal diets and activity levels and subsequently wore an activity monitor for a week to gauge how much they generally moved.

Then half of the volunteers spent two weeks moving about half as much as they had before. The other 11 volunteers began moving around about twice as much as before, for a daily total of at least 12,000 steps a day, or about six miles.

After a rest period of a week, the groups switched, so that every volunteer had moved a lot and a little.

Throughout, they also consumed two fructose-rich servings of a lemon-lime soda, designed to provide 75 grams of fructose a day, which is about what an average American typically consumes. The sodas contained about 250 calories each, and the volunteers were asked to reduce their nonfructose calories by the same amount, to avoid weight gain.

After each two-week session, the volunteers returned to the lab for a repeat of the metabolic and health tests.

Their results diverged widely, depending on how much they'd moved. As one of two new studies based on the research, published in May in Medicine & Science in Sports & Exercise, reports, after two weeks of fructose loading and relative inactivity, these young, healthy volunteers displayed a notable shift in their cholesterol and health profiles. There was a significant increase in their blood concentrations of dangerous very-low-density lipoproteins, and a soaring 116-percent increase in markers of bodily inflammation.

The second study, published this month in The European Journal of Clinical Nutrition, focused on blood-sugar responses to fructose and activity, and found equally striking changes among the young people when they didn't move much. Two weeks of extra fructose left them with clear signs of incipient insulin resistance, which is typically the first step toward Type 2 diabetes.

But in both studies, walking at least 12,000 steps a day effectively wiped out all of the disagreeable changes wrought by the extra fructose. When the young people moved more, their cholesterol and blood sugar levels remained normal, even though they were consuming plenty of fructose every day.

The lesson from these studies is not that we should blithely down huge amounts of fructose and assume that a long walk will undo all harmful effects, said Dr. Bidwell, who is now an assistant professor of exercise science at the State University of New York in Oswego. "I don't want people to consider these results as a license to eat badly," she added.
But the data suggests that "if you are going to regularly consume fructose," she said, "be sure to get up and move around."

The study did not examine how activity ameliorates some of the worst impacts of fructose, but it's likely, Dr. Bidwell said, that the "additional muscular contractions" involved in standing and taking 12,000 steps a day produce a cascade of physiological effects that alter how the body uses fructose.

Interestingly, the young people in the study did not increase the lengths of their normal workouts to achieve the requisite step totals, and most did not formally exercise at all, Dr. Bidwell said. They parked their cars further away from stores; took stairs instead of elevators; strolled the campus; and generally "sat less, moved more," she said. "That's a formula for good health, in any case," she added, "but it appears to be key," if you're determined to have that soda.

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Well: The Problem With Reclining Airplane Seat Design

The Well Column

Tara Parker-Pope on living well.

To recline or not to recline? That is the question now being hotly debated among air travelers after three flights were forced to land after passengers on board began fighting about reclining seats.

But are passengers really the problem? The real issue may be that most airline seats are not designed to fully accommodate the human body in its various shapes and sizes.

"We are fighting each other, but the seats are not designed right," said Kathleen M. Robinette, professor and head of the department of design, housing and merchandising at Oklahoma State University. "The seats don't fit us."

Dr. Robinette would know. She is the lead author of a landmark anthropometric survey conducted by the Air Force with a consortium of 35 organizations and published in 2002. It is widely used by seat makers and other designers.

The survey, called the Civilian American and European Surface Anthropometry Resource project, measured the bodies of 4,431 people in North America, the Netherlands and Italy. The survey collected a voluminous amount of data about its subjects, ranging from height and weight to shoe and bra size. Dr. Robinette and her colleagues made 3D scans of their subjects, allowing for detailed measurements in sitting and standing positions.

For seat designers, the most relevant data came from measurements of people sitting, which included distances from the buttock to the knee, the breadth of the hips and the height of the knees.

The data gave an accurate view of the variations in the human form, Dr. Robinette said, but the measurements have not been used correctly.

Seat designers often make the assumption that nearly everyone will be accommodated if they design a seat for a man in the 95th percentile of measurements, meaning that they are larger than all but 5 percent of other men — and, theoretically, all women. But even in that group, there are big differences.

Take the buttock-to-knee measurement of the largest men in the study: In the North American group, the average measurement was 26.5 inches, but the Dutch men were larger, measuring 27.6 inches. Factor in the fact that nobody on an airplane sits upright with the knees bent at a 90 degree angle, plus variations in calf length and thigh length.

The result is that the measurements don't really account for different body shapes and variations in the way people sit.In addition, choosing the 95th percentile of men as a cutoff means at least 5 percent, as many as 1 in 20 men, on the plane will be using seats that are too small for them. "That's about 10 people on every plane who are dis-accommodated, as well as all the people sitting next to them," Dr. Robinette said.

A big flaw in seat design, however, is that men in the 95th percentile are not necessarily larger than women, particularly in the parts of the body that are resting on the seat.

In terms of hip width, women are bigger than men. In the study, North American women in the 95th percentile had hip breadth measurements of 19.72 inches, compared to 17.15 inches for North American men.

According to SeatGuru.com, which collects data on seat sizes from dozens of airlines, the typical economy class airline seat ranges from 17 to 18 inches across. This means that seats will be snug on many bodies; for about 1 in 4 women, the seat will be too small at the hips, causing them to spill over into the adjacent seat.

Further, the widest part of the body is actually the shoulders, which is why so many of us end up knocking elbows and shoulders with the passengers next to us, or leaning into the window or aisle to avoid pressing against our seat neighbor.

The issue goes beyond passenger comfort. Dr. Robinette notes that travelers who are squeezed together and touching continually are more likely to spread cold viruses or other illnesses to a fellow passenger. People who are confined to tight seats and who can't move comfortably are at risk for painful "hot spots" — precursors to the bed sores that occur in nursing home patients who aren't moved frequently.

Of greater concern is the risk of blood clots, including a potentially deadly condition called deep vein thrombosis.

"When sitting in a way so you can't move, you start to get spots that are compression spots after maybe a half-hour or so," Dr. Robinette said. "Pain and discomfort is your body telling you something is wrong, and on an airplane there is a risk of blood clots. It's a serious problem that we are all discounting."

When it comes to reclining a seat, the most important measure of comfort is seat pitch, which is the distance from any point on one seat to the exact same point on the seat in front or behind it.

According to SeatGuru, seat pitch is a good approximation of how much seat and leg room a passenger can expect. The measurement on short-haul flights averages about 31 inches on most flights, ranging from a tight 28 inches on some airlines to a roomy 38 to 39 inches on a few.

"Seat pitch is what most fliers are concerned about," said Jami Counter, senior director of SeatGuru and TripAdvisor. "When you are talking about 31 inches as the standard, that's pretty tight; 28 inches is incredibly tight. Airlines are feeling really crowded and really cramped."

Officials at Recaro Aircraft Seating, a German seat manufacturer, said that seat design had to take into account safety requirements, weight, passenger comfort and airplane space needs, and have enough flexibility that seats can be used in various aircraft layouts.

Recaro has introduced a new seat with a slimmer back rest, giving the passenger behind the seat more space for knees and shins. The designers also moved the seat pocket above the tray table to allow for more knee room.

Recaro has received orders for more than 200,000 of the seats since introducing the model in late 2010.

"Of course, it is possible to install seats in an aircraft at a more comfortable distance from each other, so that everybody has sufficient knee and leg space," Rene Dankwerth, the vice president of research and development at Recaro, said in a written response. "However, the ticket price would definitely rise."

At 6 feet 6 inches, Chicago economics professor Devin Pope knows the risk of sitting behind someone who chooses to recline the seat. Dr. Pope likened it to a classic economics experiment called the Dictator game, in which a person is given $10 and allowed to keep it all, or share it with another person. Surprisingly, the dictator often chooses to share the money.

"It suggests that people really do care about other people sometimes," said Dr. Pope, associate professor of behavioral science at the University of Chicago's Booth School of Business. "I think it suggests why a lot of people don't lean the seat back."

 

A version of this article appears in print on 09/09/2014, on page D1 of the NewYork edition with the headline: Taking a Position on Plane Comfort.

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Well: In Prediabetes, a Chance to Avert Crisis

Personal Health

Jane Brody on health and aging.

After a routine test of her blood sugar eight years ago, Randi Sue Baker, a seriously overweight 64-year-old, learned that Type 2 diabetes was bearing down.

With that test result, she joined the 79 million Americans over the age of 20 who have prediabetes. Up to 70 percent of them will go on to develop diabetes, but 90 percent don't even know they are at risk. In fact, as many as 28 percent of adults with full-blown diabetes don't know they have it, according to Edward W. Gregg, a senior epidemiologist at the Centers for Disease Control and Prevention.

Ms. Baker, who lives in Brooklyn, considers herself lucky to have been forewarned. She realized that while she was still relatively healthy, she could make a concerted effort to stay that way.

For the last several years she has kept track of her caloric intake, the kinds and amounts of the carbohydrates she eats, and the overall healthfulness of her diet. She exercises five days a week, walking for 30 minutes and then swimming for an hour at the local Y. She is down 50 pounds from her top weight.

Ms. Baker also daily monitors her blood sugar, or glucose, level and takes a drug called metformin to help keep it within a normal range. Periodically, her doctor checks her blood level of hemoglobin A1C, another indicator of diabetes, to be sure it hasn't risen.

Could Ms. Baker do more? If she were willing to undergo bariatric surgery, perhaps. The operation has risks but has been shown to "cure" diabetes in about a third of patients.

But what Ms. Baker already is doing to keep diabetes at bay is far more than most people who are likely to develop it do.

Diabetes is now an out-of-control epidemic responsible for a devastating toll in health, lives and medical care costs. In 2012 the condition accounted for $245 billion in health care expenses, about one in five health care dollars.

Among its serious complications are heart disease, stroke, kidney damage, nerve damage, eye disease (which can lead to blindness), foot damage (which can lead to amputations) and hearing loss.

Diabetes is the No. 1 cause of blindness, kidney failure and amputations, Dr. Elizabeth Seaquist, an endocrinologist and diabetes expert at the University of Minnesota, said in an interview. The condition even has been linked to dementia, including Alzheimer's disease.

The two primary causes of Type 2 diabetes — obesity and inactivity — have thus far resisted countless efforts to reverse or prevent them. National data from 2000 to 2011 show that about 40 percent of adults face a lifetime risk of developing diabetes, an increase of up to 20 percent since the late 1980s, Dr. Gregg and his colleagues recently reported.

If this tsunami continues to roll forward, experts predict that by 2050 the number of adults with diabetes will reach one in three.

The risk of developing diabetes rises with age. Currently about one in four Americans ages 65 and older has diabetes, and the number will grow as the population ages.

In theory, it is possible to avert the impending health crisis. Because complications typically take 20 years to become apparent, identifying people at risk of diabetes early and taking corrective action could delay onset of the disease and its devastating consequences, perhaps for the rest of their lives.

The American Diabetes Association has created a simple seven-question test to help people assess their risk; a paper copy can be found at www.diabetes.org. Important factors include a family history of the disease, prior gestational diabetes, being overweight or obese, physical inactivity and older age.

A dozen years ago in its journal, Diabetes Care, the association noted "growing evidence that at glucose levels above normal but below the threshold diagnostic for diabetes, there is a substantially increased risk of cardiovascular disease and death."

A person with prediabetes has a blood glucose level higher than normal but not yet in the range of diabetes. While not everyone with the condition will progress to full-blown diabetes, over time, prediabetes can cause much the same underlying damage to body tissues and organs.

The trouble starts even before glucose levels begin rising, when the body becomes resistant to the effects of insulin, the pancreatic hormone that regulates how much glucose circulates freely in blood.

Insulin's main job is to move glucose from the blood into cells to be used for energy or stored for future needs. Insulin resistance, the portend of prediabetes, prompts the beta cells of the pancreas to produce more and more of this hormone to keep blood glucose levels normal.

Gradually, pancreatic cells wear out, setting the stage for rising blood glucose, prediabetes and diabetes.

The risk of developing diabetes is highest among African-Americans, Hispanics and Native Americans, but no ethnic or racial group is spared.

While excess weight is the leading risk factor, even people of normal weight can develop the disease if they carry too much fat in their abdomen. So-called central obesity may explain why the Japanese and others of Asian descent often develop diabetes at weights well below the range of obesity, Dr. Seaquist said.

She called prediabetes "a wake-up call" and emphasized that "modest weight loss can help. You don't have to lose 100 pounds to prevent diabetes." A loss of 7 percent to 10 percent of body weight can be effective.

Nor do you have to become an exercise fanatic. "Moderate activity, 30 minutes a day five or more days a week, is helpful and can even be broken up into 10-minute segments," Dr. Seaquist said. "More is better, but it's a place to start."

She also offered advice for Americans in general: "Probably we all should consider ourselves at risk. We eat too much, more than we need, and that's not healthy even if we don't get diabetes."

"We should be avoiding drinks that are high in calories," she added. "They make it too hard to regulate food intake. Drinking water is safest all around — it's natural and organic."

 

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Well: Ask Well: Is Horseback Riding Good Exercise?

Ask Well

Your health questions answered by Times journalists and experts.

Photo Credit Kike Calvo for The New York Times

A

It's very good exercise for the horse and, depending on how you ride, can be moderate or even strenuous exercise for you, too. According to a comprehensive and periodically updated scientific compilation of the energy costs of various physical activities, riding a horse requires in general about 5.5 METs, according to 2011 measurements. A MET is the metabolic equivalent of a task and measures how much energy is used during that movement, compared with being still. Sitting quietly is a 1 MET activity. For comparison, other activities at or close to 5.5 METs include recreational badminton and playing golf if you walk the course, pulling your bag of clubs.

The METs change with your mount's gait. Riding a horse at full gallop is a 7.3-MET activity, according to the compilation, similar in intensity to recreational roller blading or squash. The required exertion is a bit less than that if the horse is trotting, to 5.8 METs, and it falls drastically when riding a walking horse. That requires only 3.8 METs, the same as bowling.

Horseback riding improves muscular strength, particularly in the legs. In one study, adolescent girls who regularly rode horses had much stronger quadriceps and hamstring muscles than girls of the same age who did not ride. The equestrians did not have better bone density, though, underscoring that riding is not a weight-bearing activity, except for the horse.

Finally, if you want an even better workout from being around horses, muck out your mount's stall yourself. That work qualifies as a moderate 4.3-MET activity, the compilation finds.

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Well: Put the Physical in Education

Photo Credit Illustration by Ben Wiseman

Phys Ed

Gretchen Reynolds on the science of fitness.

When confronted with an overly active child, many exasperated teachers and parents respond the same way: "Sit still!" It might be more effective, though, to encourage the child to run. Recent research suggests that even small amounts of exercise enable children to improve their focus and academic performance.

By now it's well known that diagnoses of attention deficit hyperactivity disorder are increasingly widespread among American children: The label has been applied to about 11 percent of those between the ages of 4 and 17, according to the latest federal statistics. Interestingly, past studies have shown a strong correlation between greater aerobic fitness and attentiveness. But these studies did not answer the question of which comes first, the fitness or the attentional control.

Addressing that mystery was a goal of a study published last year in The Journal of Pediatrics. Researchers at the University of Illinois at Urbana-Champaign recruited 40 8-to-10-year-old boys and girls, half of whom had A.D.H.D. They all took a series of computerized academic and attentional tests. Later, on one occasion they sat and read quietly for 20 minutes; on another, they walked briskly or jogged for 20 minutes on treadmills. After each task, the children wore caps containing electrodes that recorded electrical activity in the brain as they repeated the original tests.

The results should make administrators question the wisdom of cutting P.E. classes. While there were few measurable differences in any of the children's scores after quiet reading, they all showed marked improvements in their math and reading comprehension scores after the exercise. More striking, the children with A.D.H.D. significantly increased their scores on a complicated test, one in which they had to focus on a single cartoon fish on-screen while other cartoon fish flashed on-screen to distract them. Brain-wave readings showed that after exercise, the children with A.D.H.D. were better able to regulate their behavior, which helped them pay attention. They responded more nimbly to mistakes like incorrect keystrokes. In short, the children with A.D.H.D. were better students academically after exercise. So were the students without A.D.H.D.

"In terms of a nonpharmacological means of dealing with attentional-control problems in children, exercise looks as if it could be quite beneficial," says Charles Hillman, the professor of kinesiology at the University of Illinois who oversaw the study. "Especially since it seems to also improve the academic performance of children who don't have attentional-control problems."

What's more, adds Matthew Pontifex, now an assistant professor at Michigan State University and the study's lead author, "You don't need treadmills." Just get restless children to march or hop or in some fashion be physically active for a few minutes. Coax their peers to join in.

Of course, even as it reinforces the accumulating evidence that exercise is good for brains, this short-term study leaves many questions unanswered: How much and what kind of physical activity is optimal? Does it permanently lessen attentional problems? Does exercise directly affect attention at all? In their study, the researchers speculate that exercise might sharpen mental focus in part by increasing brain activity in the frontal lobe. But understanding its mechanisms may not be needed for teachers and parents to consider deploying movement to counter wandering attentions.

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