Spotlight On: Tuberculosis

Pulmonary Tuberculosis

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If you’ve ever volunteered or worked in a hospital, nursing home or laboratory, you may remember having a tuberculosis (TB) skin test. But did you fully understand what TB is and why the tests are necessary? Though TB may not seem to be a major health concern in the U.S., this cunning disease remains a leading cause of death worldwide and a major risk to people with weak immune systems.

A strain of bacteria called Mycobacterium tuberculosis causes TB. People who are exposed to the bacteria may develop a form of the disease without actually being sick. This is called latent TB infection and means the body is able to fight the bacteria without spreading it to others. However, if the immune system is not in top-notch shape, the bacteria can multiply and develop into a dangerous active infection. Active TB infection is very serious and can be deadly if not treated.

An active TB infection can be spread easily, especially when the disease attacks the lungs (pulmonary TB). The bacteria spreads from one person to another through the air. When someone with active pulmonary TB coughs or even speaks, tiny droplets sent out from the lungs carry bacteria through the air. The droplets can easily be inhaled by others, especially in close contact. Common symptoms of pulmonary TB include chest pain, coughing—sometimes coughing up blood and mucus—and wheezing. People with active TB infection may also feel weak and have fever, chills or no appetite.

You might wonder what all this has to do with skin tests. Because active TB is so dangerous and because latent TB can develop into active disease, people who have a high risk of developing TB and their caregivers need to be tested for the disease. A small amount of solution containing an inactive part of the bacteria is injected under the skin. If the skin at the injection site doesn’t change, everything is fine. But if the skin becomes red or swollen, this indicates there are TB bacteria in the body and treatment is necessary.

Although the number of people infected in the U.S. has been steadily declining, more than 10 million people worldwide were sickened by TB in 2016. March 24 is World Tuberculosis Day. Learn more about how to stop the spread of TB.

Audrey Vasauskas

Curcumin, the Golden Spice

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Growing up, I enjoyed spending time in my grandmother’s kitchen. Her cooking usually involved an array of colorful spices, including a generous mix of curry powder in nearly every Indian recipe. You can’t mistake the tantalizing smell—cooking with this yellow-tinted powder can fill a room quite quickly. But it appears that there is much more to the aromatic spice than first meets the nose. It may help maintain heart health, too.

Turmeric, one of the spices that make up curry powder, contains curcumin. Evidence suggests that consuming curcumin has a wide range of physiological effects that may be beneficial to health. Curcumin is rich in antioxidants and acts as an anti-inflammatory, which may help explain its ability to promote nitric oxide (NO) availability. NO is a key compound in maintaining the health of our blood vessels. Scientists think that the body makes less NO and more becomes inactive as we age. Consequently, there is less available as we get older.

Also as we age, our blood vessels aren’t able to expand (dilate) as well. They become stiffer and less flexible and more likely to become clogged. Older people have a greater risk for developing high blood pressure due to the increased stiffness and reduced flexibility of the blood vessels. This process is called vascular aging. Women appear to experience vascular aging more quickly after menopause when the hormone estrogen is no longer produced.

A study of healthy middle-aged and older women in Japan found that taking curcumin supplements for eight weeks improved the blood vessels’ ability to dilate and reduced stiffening of the carotid artery in the neck. A recent study in the Journal of Applied Physiology found that exercise training alone does not protect against blood vessel stiffening in postmenopausal women. Therefore, combining exercise training with curcumin may be a promising way for women to slow down the steep decline in vascular health after menopause.

Another study of healthy middle-aged and older adults found that 12 weeks of curcumin supplementation improved NO availability and reduced oxidative stress (a type of cell damage) to improve blood vessel function.

These studies show promise for curcumin as a preventive therapy to lower heart disease risk in both men and women.

It seems that this golden spice really is a spice for life and may help prevent cardiovascular disease—the leading cause of death in the United States and worldwide—in older people.

March is National Nutrition Month. Learn more about how eating a balanced diet can improve your health at the Academy of Nutrition and Dietetics website.

Yasina Somani cropYasina Somani, MS, is a PhD student in the Cardiovascular Aging and Exercise Lab at Penn State. She is interested in studying the effects of novel exercise and nutritional therapies on cardiovascular outcomes in both healthy and clinical populations.

Childhood Stress + Immune Overactivity = High Blood Pressure in Adulthood?

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About 35 million adults in the U.S. may develop high blood pressure because of negative events that happened to them during childhood. Researchers are exploring how an event you experience when you’re a kid can cause high blood pressure as an adult.

About 35 million children in the U.S. experience early-life stress (ELS). ELS is any traumatic event that occurs for an extended period of time to a child younger than 10. These experiences may range from emotional, sexual or physical abuse to parental divorce or growing up in a low-income household. ELS often has negative health effects—including high blood pressure—throughout a person’s adult life.

High blood pressure occurs when the force of the blood passing through the blood vessels remains higher than normal. If the pressure is not controlled, the blood vessels become stiff over time, which reduces blood flow and oxygen to the heart and increases the risk of heart failure or heart attack. High blood pressure can also cause severe damage to blood vessels in the kidneys and may eventually lead to chronic kidney disease, a condition in which the kidneys are no longer able to filter blood to remove toxic waste from the body. People with severe chronic kidney disease require a treatment called dialysis to keep them alive. During dialysis, a machine removes waste and excess water from the blood, effectively acting as an artificial kidney outside the body.

Because of these potential complications, it’s important to understand how ELS puts people at risk for high blood pressure. Numerous studies have shown that activation of immune cells can make high blood pressure worse. A recent study explored how ELS affects the immune system in rat kidneys, the organs responsible for long-term blood pressure control. The study found that rats exposed to ELS had higher numbers of immune cell markers and more immune cell activation in their adult life. Prolonged immune cell activation can prevent the kidneys from working properly, which may cause high blood pressure later on.

Interestingly, the study also found that when the immune cells in the kidneys of ELS rats were stimulated they showed that the immune cells were overactive. This finding is important because it shows researchers are starting to understand more about the link between ELS and high blood pressure. However, more research is needed to fully establish a connection between childhood trauma, the immune response of the kidneys and high blood pressure in adulthood.

Ijeoma ObiIjeoma Obi, MS, is a PhD candidate in the University of Alabama at Birmingham’s Department of Medicine, Nephrology Division, Section of Cardio-Renal Physiology and Medicine.

Can Eating Fruit Be Hazardous to Your Health?

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The U.S. Department of Agriculture recommends two cups of fresh, frozen, canned or dried whole fruits each day for most people following a 2,000-calorie diet. However, some people have difficulty breaking down fruit in their digestive tract or absorbing fructose into their bloodstream. Fructose is a type of sugar that is naturally found in fruit. Humans have a limited ability for absorbing fructose. A special protein called GLUT5 carries fructose into the small cells of the intestines, and another protein called GLUT2 takes fructose from the cells and into the bloodstream.

People with fructose malabsorption (formerly called dietary fructose intolerance) have a deficiency of GLUT5 in their intestinal cells. Bacteria in the intestinal tract break down the fructose that the body can’t absorb. The undigested fructose forms gas and often causes gastrointestinal discomfort. Symptoms may include bloating, gassy pain and diarrhea. Up to 50 percent of adults can’t absorb large amounts of fructose, and about 10 percent can’t absorb even moderate amounts of fructose.

In addition to fruit, a number of sweeteners are high in fructose. High-fructose corn syrup, honey, maple-flavored syrup, molasses, sorghum and invert sugar may also cause uncomfortable symptoms. One possible reason why fructose malabsorption rates in the U.S. are high is from the widespread consumption of beverages—such as soft drinks—sweetened by high-fructose corn syrup.

People who have fructose intolerance should limit their consumption of high-fructose foods, such as:

  • fruit juices,
  • apples,
  • grapes,
  • watermelon,
  • asparagus,
  • peas, and
  • zucchini.

Fruits and vegetables that are lower in fructose may be easier to digest, especially when they are part of a full meal. Lower-fructose foods include:

  • bananas,
  • blueberries,
  • strawberries,
  • carrots,
  • avocados,
  • green beans, and
  • lettuce.

So, if you are trying to eat the recommended servings of fruit every day but have digestion issues, ask your doctor if you may have fructose malabsorption and try lower-fructose foods as an alternative.

barb-goodmanBarb Goodman, PhD, is a professor of physiology at the University of South Dakota.

In Heart Disease, Women and Men Are Not Created Equal

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It may seem as if heart disease affects mostly men, but in fact it’s the No. 1 cause of death for both genders—more people die from heart disease than all cancers combined. Perhaps even more surprising is that more women than men will develop heart failure or die within a year of a heart attack.

Medical professionals don’t completely understand why women have worse outcomes than men when it comes to heart disease. One factor, however, is that heart attack symptoms are often very different in women and in some cases aren’t as obvious. Like men, women may experience classic chest pain, but they may also have a variety of more general symptoms, including:

  • nausea or vomiting,
  • indigestion,
  • shortness of breath,
  • pain in the upper back or arm,
  • neck and jaw pain, or
  • unusual fatigue.

Sometimes these symptoms may fade and reappear.

Men and women often have different types of artery disease. This may be a key to why symptoms are not the same. Men are more likely to have significant blockage of a major artery whereas many women have no evidence of arterial blockage. Women are more likely to have microvascular disease, which affects the heart’s smaller blood vessels.

Because many people believe that women are less likely to have a heart attack—combined with the differences in symptoms—may be why women don’t always realize they are having one. As a result, they may not seek treatment immediately. In one study, women did not get medical treatment for an average of 50 hours, compared to fewer than 16 hours for men. A delay in treatment contributes to a greater chance of dying from a heart attack.

In the emergency room, the lack of classic heart attack symptoms can lead to misdiagnosis, resulting in a delay in treatment. Studies show that women are less likely to receive appropriate treatment for heart attack compared to men. Even when they are treated appropriately, women often experience a higher risk of complications.

Although there have been tremendous improvements in the treatment of heart disease in women, more still needs to be done. Increased education and improved training will help the general public and medical professionals recognize the differences between men’s and women’s symptoms. In addition, more clinical research is needed to understand the reason for these gender-related differences and to better personalize the management of heart disease in women.

February is American Heart Month. Visit the American Heart Association’s website to learn more about heart disease in women.


John ChathamJohn Chatham, DPhil, is a professor of pathology and director of the Division of Molecular and Cellular Pathology at the University of Alabama at Birmingham.


Why Marriage Is Good for Your Heart

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Valentine’s Day is a time when many of us reflect on the importance of our closest relationships. Whether they include family, friends or a significant other, science is not silent on the impact these relationships have on our health. A review of 148 studies reveals that strong social relationships are associated with a 50 percent increased likelihood of survival, regardless of medical condition. Other studies link low social support to an increased risk and incidence of heart disease. The newest research, however, explores the effect our most intimate relationships—with a romantic partner—have on heart health.

A study that looked at more than 6,000 people reports that being single is associated with heart disease. Specifically, people who were single had a 45 percent higher rate of death from heart disease than those who were married. A striking finding in this study was that even though the reason for being unmarried varied among the participants—some people had never married, others were divorced, separated or widowed—the risks were consistently lower in married people. From these results, the overall benefit of the spousal relationship on heart health seems clear.

Many factors may account for the positive effect of marriage on heart health, including:

  • improved social support,
  • a less sedentary lifestyle, and
  • increased motivation to make healthy lifestyle changes.

The quality of marital relationships over time also influences heart disease risk factors. Men who described their relationships as “improving” had a lowering of risk factors compared to those in marriages categorized as “consistently good” or “deteriorating.”

In other words, marriage is generally good for your heart health and even better when you work to improve that relationship over time. So as you think about those closest to your heart on Valentine’s Day, do your heart a favor and take your sweetheart on a date.

Shawn Bender, PhD

Shawn Bender, PhD, is an assistant professor at the University of Missouri and a research health scientist at the Harry S. Truman Memorial Veterans’ Hospital.

In Hot Water

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This week, the I Spy Physiology blog answers a reader question: Why do we get dizzy when getting out of a hot tub?

There may not be a better way to chase away the winter “blahs” than soaking in the hot tub or standing under a steaming shower. However, sometimes, after a lengthy soak or steam you may feel lightheaded when you stand up. You may start to feel woozy and your balance may waver. You may even see stars for a moment or faint. Why does this happen?

When body temperature rises due to hot water, hot weather or fever, the body activates mechanisms to cool down toward normal temperature (97–99°F). The blood coursing through the body must rise to the surface of the skin, releasing heat, to reduce core temperature. This happens through a process called vasodilation. During vasodilation, blood vessels carrying blood away from the heart (arteries) open up to allow a larger volume of blood to flow through them. Blood flowing through the arteries near the skin’s surface releases heat into the environment and cools the body. However, when many arteries open up at the same time (while a person is standing up), gravity pulls the blood into the legs and away from the brain and heart. Pooling of blood in the legs can cause dizziness or lightheadedness because the brain and heart aren’t getting enough blood.

Lightheadedness and even fainting are the body’s way of “fixing” the lack of blood in the brain and heart. Once the brain, heart and legs are at the same level (when a person is lying down), blood flows into each organ more easily because gravity no longer pulls so much blood into the legs. Flexing the muscles is another way to return more blood to the brain and heart. Muscle contraction works against gravity and forces blood back to the heart and ultimately the brain. This provides the brain with enough blood volume to eliminate wooziness.

The next time you are enjoying a dip in a hot tub or a steaming shower, pause, flex your muscles and steady yourself before stepping out.

Jessica Taylor 2017Jessica C. Taylor, PhD, is the Senior Manager of Higher Education Programs at the American Physiological Society. She is a cardiovascular physiologist, exercise enthusiast and firm believer in warming up in hot water.

Why Does Muscle Matter?

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When young people think about their muscles, they often focus on enhancing their muscle size and strength for cosmetic or athletic reasons. Those older than 50, however, need to be more concerned with just keeping the muscle they have. On average, people over the age of 50 lose 1 to 2 percent of their muscle mass each year, and after age 60, this number increases to 3 percent. Bed rest, lack of exercise and sedentary behavior in the elderly can speed up this gradual loss over time. Why is maintaining muscle so important for the elderly?

The simplest reason is that muscle is essential for all kinds of movement. Mobility is a crucial component of maintaining independence as we age. Adequate muscle mass and strength allow seniors to continue performing simple daily activities—things like bathing, getting dressed and preparing food—without assistance. Another less obvious reason is that muscle burns a large percentage of the energy that we get from the foods we eat. Losing muscle mass means that we do not use the energy from food as effectively, which can lead to chronic health conditions. In fact, loss of muscle mass is a major contributor to the increased rates of type 2 diabetes in older adults.

Current research has revealed, however, that muscle size is not the only, or even best measure of muscle health. Scientists have traditionally used the term “sarcopenia” to refer to aged-related loss of muscle mass, but many scientists are now focusing more on “dynapenia,” which indicates the loss of muscle function due to aging. New research is showing that how well muscle works can be just as important as how much muscle mass remains. In fact, a person with a smaller amount of muscle mass whose muscle function is good may be stronger and healthier than someone with more muscle mass but poor muscle function. This realization has led to new strategies for promoting muscle health in aging. Although maintaining muscle mass is still important, new approaches are targeting improvement in muscle function. These strategies go beyond simply lifting weights and look at ways to make the inner machinery of the muscle work better. Although nothing can completely stop the loss of muscle function with age, promising new nutritional and exercise therapies are emerging to substantially slow the decline, helping seniors stay active and independent for as long as possible.

Ben MillerBenjamin Miller, PhD, is an associate professor in the department of Health and Exercise Science at Colorado State University. He co-directs the Translational Research in Aging and Chronic Disease (TRACD) Laboratory.

Relieve Stress and Anxiety with Exercise in the New Year

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If getting more exercise is one of your New Year’s resolutions, here is another reason to stick with it: daily exercise—which is known to lower blood pressure—has also been shown to reduce stress and anxiety. I am not the first to notice that physical activity improves my ability to respond to stressful situations, but as a physiologist, I naturally wonder about the biological basis of this observation.

The hippocampus—one of the brain regions that regulates anxiety levels—becomes activated during both exercise and stress. Research suggests that exercise can calm some of the nerve cells in the hippocampus that become overstimulated during times of stress. While we don’t fully understand the mechanisms, we do know that certain chemical signals in the brain inhibit nerve cell activity, and some of these signals are likely responsible for the observed reduction in stress and anxiety.

Reduced anxiety and stress immediately after physical activity is not the only benefit of exercise. Blood pressure also declines to healthier levels within minutes after exercising. Studies suggest that exercise causes vasodilation, or widening of the blood vessels. When blood vessels open wider, it allows the blood to flow more easily, thereby lowering the pressure of the blood inside the vessels. Activation of histamine receptors is one mechanism that contributes to the reduction in blood pressure following exercise.

While there are many other benefits to regular exercise, the reductions in stress and blood pressure occur immediately and last for many hours. So, consider engaging in a physically active lifestyle that includes daily exercise, and encourage family and friends to join in. The result could be less stress, less anxiety, and lower blood pressure. What better way to start 2018?

william-farquharWilliam B. Farquhar, PhD, is a professor in the department of kinesiology and applied physiology at the University of Delaware. In addition to being a member of the American Physiological Society, he is a Fellow of the American College of Sports Medicine.


How Are Gut Bacteria and Bone Related?

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Your gut contains tens of trillions of microorganisms, including at least 1,000 different species of known bacteria. Even though these bacteria are microscopic in size, they are so abundant that they make up 1 to 3 percent of your total body mass! Many of these microorganisms that live in the body are actually beneficial to your health, although some can be harmful. The “good” bacteria in your digestive system protect your body by preventing the growth of “bad” bacteria that can make you sick. They also serve an essential function in food digestion by breaking down foods and proteins and synthesizing vitamins and nutrients. Recently, researchers have shown that gut bacteria, or microbiota, may play a role in diseases such as diabetes, obesity and Alzheimer’s disease, and they can affect distant organs such as the brain and even bone.

One of the ways that the gut affects bone is by regulating mineral absorption. As food passes through the body, the gastrointestinal (GI) system controls the amount of minerals that are absorbed from the food into the bloodstream. Many of these minerals—including calcium, phosphorous, and magnesium—are essential for healthy bones. In fact, studies report that people with GI diseases such as inflammatory bowel disease can experience bone complications.

Other research has added support to the theory that gut bacteria may affect the bone by contributing to the absorption of nutrients. Mouse studies have shown that the presence or absence of gut microbiota can actually change the structure and density of bone. Bone density, or bone mass, is one indicator of how strong and healthy your bones are. It’s not exactly clear how or why gut bacteria affect bone, but researchers believe that one way is by regulating how much calcium is absorbed into the body.

Taking probiotics is known to help maintain a healthy gut microbiota. Probiotics are live bacteria that can be taken by mouth as a dietary supplement. They contribute to the health of the digestive system by promoting the growth of good bacteria and inhibiting harmful bacteria. But new research is showing that they can also have beneficial effects on the bone.

While scientists continue to explore the link between the gut bacteria and bone, a few lifestyle adjustments can help protect your bones:

  • Include plenty of calcium and vitamin D in your diet.
  • Exercise regularly (preferably with weight-bearing exercises that strengthen your bones).
  • Quit smoking and limit alcohol consumption.
  • Avoid using steroid drugs, which can weaken your bones.
  • Get bone mineral density testing according to the schedule recommended by your doctor.

Naiomy Rios-Arce cropNaiomy Rios-Arce, BS, is a PhD candidate in the Comparative Medicine and Integrative Biology program in the Department of Physiology at Michigan State University. Her research focuses on understanding the mechanism by which probiotics can affect bone density. Naiomy is originally from Hatillo, Puerto Rico.