Healthy News for Healthy Nation

ScienceDaily (July 20, 2008) — Scientists have long been puzzled by how the Masai can avoid cardiovascular disease despite having a diet rich in animal fats. Researchers at Karolinska Institutet believe that their secret is in their regular walking.

There is strong evidence that the high consumption of animal fats increases the risk of developing cardiovascular disease. Many scientists have therefore been surprised that the nomadic Masai of Kenya and Tanzania are seldom afflicted by the disease, despite having a diet that is rich in animal fats and deficient in carbohydrates.

This fact, which has been known to scientists for 40 years, has raised speculations that the Masai are genetically protected from cardiovascular disease. Now, a unique study by Dr Julia Mbalilaki in association with colleagues from Norway and Tanzania, suggests that the reason is more likely to be the Masai’s active lifestyle.

Their results are based on examinations of the lifestyles, diets and cardiovascular risk factors of 985 middle-aged men and women in Tanzania, 130 of who were Masai, 371 farmers and 484 urbanites. In line with previous studies, their results show that the Masai not only have a diet richer in animal fat than that of the other subjects, but also run the lowest cardiovascular risk, which is to say that they have the lowest body weights, waist-measurements and blood pressure, combined with a healthy blood lipid profile.

What sets the Masai lifestyle apart is also a very high degree of physical activity. The Masai studied expended 2,500 kilocalories a day more than the basic requirement, compared with 1,500 kilocalories a day for the farmers and 891 kilocalories a day for the urbanites. According to the team, most Westerners would have to walk roughly 20 km a day to achieve the Masai level of energy expenditure.

The scientists believe that the Masai are protected by their high physical activity rather than by some unknown genetic factor.

“This is the first time that cardiovascular risk factors have been fully studied in the Masai,” says Dr Mbalilaki. “Bearing in mind the vast amount of walking they do, it no longer seems strange that the Masai have low waist-measurements and good blood lipid profiles, despite the levels of animal fat in their food.”

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ScienceDaily (July 9, 2008) — Researchers in Japan are reporting a discovery that could improve the effectiveness and expand the use of transplants of insulin-producing cells to treat diabetes. Insulin-dependent, or Type 1, diabetes affects about 800,000 people in the United States.

In the new study, Yuji Teramura and Hiroo Iwata point out that transplantation of the pancreas’s insulin producing cells, so-called islets of Langerhans, is a promising experimental technique for treating patients with insulin-dependent diabetes.

However, the procedure is not sufficiently effective for many people. This is because the body destroys many of the islet cells right after transplantation in an inflammatory reaction triggered by blood clotting on the surface of the cells, the researchers say.

To address this problem, the scientists coated islet cells with a special polymer film containing heparin, an anticoagulant, or urokinase, a medication that dissolves blood clots. In laboratory studies, the researchers showed that the coatings delayed the clotting long enough to prevent the destruction that otherwise would occur immediately after transplantation.

The coatings did not affect the ability of the cells to produce insulin, the researchers add.

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ScienceDaily (July 12, 2008) — How will the epidemic of childhood obesity today affect the future health of Americans? As concern about children’s health grows along with their waistlines, medical experts fear that the childhood obesity epidemic could lead to large numbers of younger adults developing type 2 diabetes, causing serious and lasting health complications for future generations of Americans.

In a new article, University of Michigan C.S. Mott Children’s Hospital pediatric endocrinologist Joyce Lee, M.D., M.P.H, warns that the most damaging effects of childhood obesity have yet to surface, and will likely result in an epidemic of type 2 diabetes among young adults, leading to a greater number of diabetes complications, and ultimately, lower life expectancy.

“The full impact of the childhood obesity epidemic has yet to be seen because it can take up to 10 years or longer for obese individuals to develop type 2 diabetes,” says Lee, a member of the Child Health Evaluation and Research (CHEAR) Unit at Mott. “Children who are obese today are more likely to develop type 2 diabetes as young adults.”

The longer a person has diabetes, Lee says, the more likely he or she is to develop devastating complications. Young adults with type 2 diabetes are therefore more likely to develop complications such as blindness and kidney failure during their lifetimes, and they have higher rates of diabetes complications and heart disease than older adults with type 2 diabetes.

Plus, babies born to young women with type 2 diabetes are at greater risk for obesity and type 2 diabetes, creating a vicious cycle.

“Recent studies suggest that there have been dramatic increases in type 2 diabetes among individuals in their 20s and 30s, whereas it used to be that individuals developed type 2 diabetes in their late 50s or 60s, “ notes Lee, assistant professor in the Department of Pediatrics and Communicable Diseases at the U-M Medical School. “This may be the first indication of a type 2 diabetes epidemic among young adults who were obese during childhood.”

Given the delayed negative effects of childhood obesity, Lee says that there needs to be a greater overall investment in childhood obesity, to prevent development of type 2 diabetes.

“Our society heavily invests in the treatment and management of chronic diseases like type 2 diabetes for adults. But it spends very little for the prevention and treatment of childhood obesity to stave off the onset of type 2 diabetes,” says Lee.

“If there isn’t a significant investment in obesity prevention and treatment during childhood within schools, communities, and the health care system, recent trends in childhood obesity will likely lead to increases in type 2 diabetes among young adults, resulting in even greater costs to society and the health care system.”

Lee notes that further studies are needed to learn more about how trends in childhood obesity will impact future rates and age at onset of type 2 diabetes.

These studies will help assess the future burden of disease and disability in the population, and to evaluate whether interventions in childhood can successfully prevent individuals from developing type 2 diabetes over their lifetimes.

Funding: Lee’s work on this study was supported by the U-M Clinical Sciences Scholars Program.

Reference: Archives of Pediatric & Adolescent Medicine, July 2008, Vol. 162, No. 7.

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ScienceDaily (July 17, 2008) — Researchers have devised an ultrasound imaging technique that can spot early signs of peripheral arterial disease that current conventional tests miss and thereby prevent the serious complications that can result, including gangrene and death.

The test, if approved for clinical use, could lead to early treatments that would head off the serious complications that can result from the disease. PAD, a condition in which atherosclerosis of the blood vessels in the legs limits blood flow, affects about 8 million Americans, particularly those older than 65 (American Heart Association statistics). Its presence raises the risk of a heart attack or stroke to four to five times that of the general population.

The disease poses particular dangers for diabetics because of the risk of infections and gangrene that can lead to amputations and death. PAD frequently goes undiagnosed in its early to mid stages. One of the reasons for this is the lack of cost-effective diagnostic tools capable of detecting PAD before it has grown serious. By contrast, cardiologists can noninvasively detect early signs of heart disease by imaging blood flows during exercise stress tests. No equivalent stress test has been available for PAD.

Lead investigator Jonathan R. Lindner, M.D., professor of medicine (cardiovascular medicine) at the Oregon Health & Science University School of Medicine, and his associates devised such a test for use in a study involving 26 control subjects with no history of coronary disease, hypertension or diabetes, and 39 patients with symptomatic PAD, of whom 19 had type 2 diabetes. Lipid-shelled microbubbles were injected intravenously as an ultrasound contrast agent to evaluate microvascular blood flow in the calf muscles of subjects’ legs at rest and during exercise. These microbubbles behave and circulate in much the way red blood vessels do and they “ring” in an ultrasound field giving off a strong signal. The results from blood flow imaging were compared with those from the most commonly used non-invasive diagnostic tests.

“We found that contrast-enhanced ultrasound imaging outperformed most conventional forms of diagnostics in measuring and evaluating impairment in a patient’s ability to recruit blood flow in the legs during modest exercise,” said Lindner. Specifically, the study found that patients with PAD had lower microvascular blood flow in their calf muscles than control subjects did after two minutes of plantar-flexion exercise in which the foot is flexed as when depressing the accelerator pedal of a car.

“Peripheral arterial disease is becoming a huge problem because of the aging of the population and the increasing incidence of diabetes,” said Lindner. “But we don’t have good diagnostics for it, partly because a lot of the methods we have are based on measuring what’s going on in the big vessels, the arteries and veins. PAD is a complex, very diffuse disease, which often involves functional abnormalities in the microcirculation system, the tiniest small vessels that go into muscle, bone, skin and connective tissues. How well the microcirculation system is functioning is what determines how well tissue is getting fed, which is the critical issue.”

Today diagnosing PAD relies mainly on detection of abnormal pulse volumes in the lower limbs, or blood pressure differences between separate readings at the ankle and the arm (the ankle-brachial index), but these are only effective in detecting moderate-to-severe cases and do not always detect disease in the small vessels.

“The real benefit of a test like this – which only takes about five minutes to do and doesn’t require anything beyond the equipment and capabilities already in place in most vascular laboratories – is their value for selecting the right therapies,” said Lindner. “There are new drugs in clinical trials at OHSU and elsewhere that involve gene and stem cell therapies aimed at improving the circulation by promoting new blood vessel growth. But the symptomatic benefits you get from these therapies generally can’t be evaluated by conventional tests because they don’t really test tissue perfusion. If you want to look at the improvement in perfusion, why not look at perfusion?”

Further studies are needed on subjects for whom no diagnosis has yet been made. The microbubbles used in the test already are approved for human use, although the PAD test is currently an off-label application. The technique does require additional training in how to receive the microbubble signals, said Lindner, but otherwise there are few significant hurdles yet to be cleared for the test to be used in vascular clinics everywhere.

The research was supported by grants from the National Institutes of Health to Lindner, to Eugene J. Barrett, M.D., Ph.D., of the endocrinology division of the University of Virginia, and to the University of Virginia General Clinical Research Center.

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