Scientists have identified the “master” stem cell that gives rise to the three types of heart cells, possibly opening the door for new methods of pharmaceutical research and heart therapies, such as growing a patch to repair cardiac tissue damaged by heart disease, according to a study published in Nature.
The research illuminates a crucial facet of how heart tissue develops and shows why past studies to repair heart tissue with stem cells had poor results: the cells used were not the heart tissue progenitors that lead author Kenneth Chien and his team identified. The researchers then purified the cells, cloned them and tracked their journey from single stem cell to the three major lineages of heart cells — smooth muscle, cardiomyocyte [or striated] muscle and endothelial cells [U.S. News and World Report], which line the inside of the heart. For years, scientists have studied the development of the heart in animals like the zebra fish, but this finding will allow researchers to closely examine the genesis of human cardiac tissue in unprecedented detail.
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The hearts of African-American adults are apparently under extraordinary stress. A broad, long-term study has found that African-Americans are developing heart failure at a rate 20 times higher than whites, and some are dying of the disease decades before the condition typically proves fatal in whites. “Blacks in our study who were in their 30s and 40s had the same rate of heart failure as whites in their 50s and 60s,” said [lead researcher] Kirsten Bibbins-Domingo…. “These are people who are in the prime of their life and should be contributing in all kinds of ways,” Dr. Bibbins-Domingo added, “so this disease has a devastating effect, not just on the individual patient but on the family, the community and society in general” [The New York Times].
Researchers say the findings show that narrowly focused research in the past has left striking gaps in our understanding of heart disease, which is the top cause of death for Americans. Says Bibbins-Domingo: “We usually thought of heart failure as a disease of older people, but that’s based on studies by mostly white participants.” … Researchers and cardiology specialists called the findings alarming and a call to action. The scientific community should step up its research on the risk factors and design clinical trials to study specialized treatment for black patients, they said [Baltimore Sun]. They also urge young African-Americans to take the threat seriously, and hedge against it with a healthy diet and exercise.
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It may be old news that people who work the night shift tend to have higher rates of certain medical conditions. But researchers say they have established a direct link between an abnormal sleep cycle and altered hormone levels, which can disrupt metabolism and increase the risk of heart disease, diabetes, and obesity. As soon as their circadian rhythms became separated from a day-night cycle, test subjects’ levels of key metabolic hormones went haywire—the most compelling evidence yet that shift work isn’t just an inconvenience, but an occupational hazard [Wired News].
The study, published in the Proceedings of the National Academy of Sciences, maps a clear path from work-sleep cycles to metabolic disregulation to disease [Wired News]. Scientists cannot yet explain the exact connection between metabolism and the circadian rhythm, the roughly 24-hour cycle that biological and behavioral processes are based on. But they believe the trigger to be a decrease in the hormone leptin, which the body uses to regulate appetite, that results when the circadian rhythm is disrupted.
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It may be a platitude that fresh, clean air is good for you, but now researchers have quantified how much cleaning up air pollution has improved the public health: It has boosted the lifespan of the average American city-dweller by five months.
Coauthor Majid Ezzatin explains that when his team examined three decades of health data from 51 U.S. cities, researchers found that people are living about three years longer than they did before. Controlling for changes in income, education, demographics and smoking, about five months of that can be chalked up to air improvements…. “Rather than just saying pollution is bad for health,” he said, “we can say that regulations are good for health” [Wired News].
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Researchers have coaxed a mouse into releasing a flood of stem cells from its bone marrow, and say these extra stem cells may then hustle off to repair damaged tissue. If this technique proves effective for repairing damage and can be transfered to humans, researchers say it could help mend everything from broken bones to damaged hearts. Says lead researcher Sara Rankin: “Suppose a person comes in to hospital having had a heart attack. You give them these drugs and stem cells are quickly released into the blood. We know they will naturally home in on areas of damage, so if you’ve got a broken bone, or you’ve had a heart attack, the stem cells will go there. In response to a heart attack, you’d accelerate the repair process” [The Guardian].
Researchers say this approach would be a more direct and less controversial way to get stem cells to patients. Instead of injecting patients with stem cells from donors, embryos or stem cell banks, doctors could simply inject the drugs and the patients would produce the cells themselves. This would avoid complications of tissue rejection and sidestep ethical objections to using stem cells originating from embryos. “It’s promoting self-healing,” says Sara Rankin…. “We’re simply boosting what’s going on naturally” [New Scientist].
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An experimental drug has shown promise in preventing emphysema in mice exposed to cigarette smoke, giving researchers new hope that they’ll soon find a way to combat one of the most stubborn, untreatable, and common killers of humans. Even though the study focuses on emphysema in mice, the researchers suggest the drug could work in people by delaying or preventing chronic obstructive pulmonary disease, which encompasses emphysema and chronic bronchitis and is the fourth most common cause of death in the United States [Science News].
The drug, called CDDO-imidazole, or CDDO-Im, works by activating a gene called Nrf2, explains study coauthor Shyam Biswal. In prior research, Biswal and colleagues found that Nrf2 works as a “master gene,” turning on genes involved in protecting the lungs from pollution and cigarette smoke. “The Nrf2 pathway is the major antioxidant and detoxifying response in the lungs. Therapies targeting this pathway need to be developed and tested in patients,” said Biswal [Reuters].
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The health benefits of eating more fish outweigh the risks of mercury poisoning, according to a new Food and Drug Administration (FDA) proposal that would revise current federal seafood advisories. The proposal is drawing fire from the Environmental Protection Agency (EPA) and environmental groups that accuse the FDA of pandering to the seafood industry. Richard Wiles, director of an environmental advocacy group, said, “This is an astonishing, irresponsible document…It’s a commentary on how low FDA has sunk as an agency. It was once a fierce protector of America’s health, and now it’s nothing more than a patsy for polluters” [Washington Post].
Currently, the government advises young children, pregnant women, and women of child-bearing age to restrict overall fish consumption to 12 ounces per week and to avoid shark, swordfish, king mackerel and tilefish, which are known to have particularly high mercury levels. Mercury in the environment accumulates in fish and studies have linked the element to developmental problems in fetuses and young children as well as cardiovascular disease in adults. However, the new FDA report says recent studies suggest “a beneficial impact on fetal neurodevelopment from the mother’s consumption of fish, even though they contain methylmercury…The net effect is not necessarily adverse, and could in fact be beneficial” [AP]. The report argued that nutrients in fish, including omega-3 fatty acids, selenium and other minerals could boost a child’s IQ by three points [Washington Post]. The new analysis places ideal fish consumption—for optimal IQ-boosting—somewhere above 12 ounces per week.
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Researchers recently went to an Amish community in Pennsylvania with an odd request: Will you drink milkshakes for the sake of science? In a study about cardiovascular health and genetics that had more than 800 Amish people slurping high-fat shakes, researchers discovered that about five percent of their subjects had a genetic mutation that defends the heart against the effects of a high-fat diet—specifically, breaking down triglycerides, those fats that clog arteries like hair in your bathroom drain [Newsweek].
In the study, published in Science [subscription required], Amish men and women agreed to drink a rich milkshake that was made mostly of heavy cream. Over the next six hours, a group of investigators took samples of their blood, determining how much fat was churning through their bloodstreams. Most of the study participants responded as expected — their levels of triglycerides, a common form of fat in the blood, rose steadily for three to four hours and then declined. But about 5 percent had an extraordinary reaction: their triglyceride levels started out low and hardly budged [The New York Times].
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Cancer will be the world’s leading killer by 2010, edging out heart disease for the top spot, according to the latest report by the World Health Organization (WHO). Though cancer rates in the United States have just recently begun to decrease, elsewhere in the world cancer is on a steady rise. Experts cite tobacco, increasingly Western lifestyles, and inadequate medical care as the factors contributing to the cancer epidemic in developing countries. “In the U.S., we pay a lot of attention to cancer trends, and the trend has been encouraging,” says Dr. Richard Schilsky… “But we have forgotten that there is a big wide world out there. Cancer is a global problem” [TIME].
According to the WHO report, 12 million new cases of cancer will be diagnosed this year and 7 million will die from the disease. The group forecast a 1 percent increase globally each year, with emerging economies such as China, Russia and India being hit the hardest [CNN]. The report also projects a 38 percent population increase in less developed countries by 2030. Taken together, that means by 2030 an estimated 20 to 26 million new cases of cancer will be diagnosed annually and 13 to 17 million deaths will be cancer-related.
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In yet another warning signal of the toll that childhood obesity will take on health and health care budgets, a small study has shown that overweight kids as young as 10 years old have the thickened arteries of 45-year-olds. Researchers say the findings raise the possibility that these kids could develop serious heart disease in their 20s or 30s. “There’s a saying that ‘you’re as old as your arteries,’ meaning that the state of your arteries is more important than your actual age in the evolution of heart disease and stroke,” said [lead researcher] Dr Geetha Raghuveer [Telegraph].
The findings, while preliminary, should serve as a serious alarm bell in the United States, where about one-third of children are overweight and almost one-fifth are obese. Many parents think that “baby fat” will melt away as kids get older. But research increasingly shows that fat kids become fat adults, with higher risks for many health problems. “Obesity is not benign in children and adolescents,” said Dr. Robert Eckel, a former heart association president [AP].
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Researchers have built a honeycomb-like scaffold that resembles natural heart tissue, and found that when they seeded the artificial structure with heart cells from young rats the cells grew and joined together in an approximation of normal heart muscle. The cells had also formed electrical connections with one another, allowing them to contract in coordination – and when an electric field was applied along the long axis of the honeycomb, the cells indeed contracted. “You could see the cells ‘beating’ on the scaffold,” says [study coauthor] George Engelmayr [New Scientist].
Other researchers have constructed biodegradable scaffolding on which to grow different types of tissue, but heart tissue poses particular technical challenges. Heart tissue must be flexible enough to change shape as the heart contracts, but also strong enough to withstand the intense forces generated by these contractions. So, the researchers used a polymer…. “It’s elastic like a rubber band,” Engelmayr says, so it can withstand repeated stretching while only gradually losing strength as it degrades [Technology Review].
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Vice-President Dick Cheney went to the hospital this afternoon after his doctors detected an abnormal rhythm to his heartbeat. He was diagnosed with atrial fibrillation, meaning that the upper chambers of his heart, the atria, weren’t beating properly, and doctors prepared to give his heart an electric shock to restore its proper rhythm.
Atrial fibrillation isn’t an immediately life-threatening condition, unlike ventricular fibrillation, when the heart’s lower chambers stop beating, blood stops pumping, and the body begins to shut down. Patients with atrial fibrillation may feel palpitations or shortness of breath, but often it causes no symptoms at all. When it happens, blood isn’t pumped completely out of the atria. That increases the likelihood that the blood will form a clot, which can then travel into the brain and cause a stroke. That’s the most important reason for treating the condition [The Wall Street Journal health blog].
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An enzyme that helps the human body break down alcohol has another beneficial function, researchers say: In rat studies the enzyme reduces the amount of damage during a heart attack. Researchers also developed an experimental drug that can increase levels of the enzyme in rats, and say these findings could lead to a drug that could prevent damage to the heart from heart attack[s] or during coronary bypass surgery and other events in which the heart does not receive enough blood [Reuters].
During a heart attack, a clot blocks blood flow to the heart. The lack of oxygen and build up of toxins causes tissue to die. This is also a danger during coronary bypass surgery, when blood flow is redirected to allow surgeons to operate [BBC News]. Researchers believe the enzyme works by removing toxic molecules known as free radicals from the cells that are struggling to live through the episode of oxygen deprivation. Although not all cardiac damage is avoided, “any time you can save cells, you have a better chance of recovery,” says study co-author Thomas Hurley [Scientific American].
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California is striking a blow against obesity and heart disease: On Friday, Governor Arnold Schwarzenegger signed a bill outlawing the use of trans fats in all restaurants and bakeries. The bill creates the first state-wide ban of trans fats, but follows the path set out by cities like New York City and Philadelphia, which have already evicted the substance from restaurants within city limits.
Trans fats are created by pumping hydrogen into liquid oil at high temperature, a process called partial hydrogenation. The process results in an inexpensive fat that prolongs the shelf life and appearance of packaged foods and that, many fast-food restaurants say, helps make cooked food crisp and flavorful [The New York Times]. The artificial fats have been shown to increase levels of “bad” cholesterol and decrease levels of “good” cholesterol, and are therefore linked to heart disease.
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In an experiment that could have applications in treating heart disease and strokes, researchers have taken certain cells from the blood and used them to grow entire networks of blood vessels in mice.
“What’s really significant about our study is that we are using human cells that can be obtained from blood or bone marrow rather than removing and using fully developed blood vessels,” said Harvard’s Joyce Bischoff, who led the study.[Reuters].
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