Category: Health

New Portable Device Quickly Measures Radiation Exposure

Scientists are developing a portable device that can measure a person's radiation exposure in minutes using radiation-induced changes in the concentrations of certain blood proteins. This image shows a magneto-nanosensor chip reader station, chip cartridge, and chip. (Credit: S. Wang)
Scientists are developing a portable device that can measure a person’s radiation exposure in minutes. This image shows a magneto-nanosensor chip reader station, chip cartridge, and chip. (Credit: S. Wang)

Picture the scene of the Fukushima nuclear accident. The Daiichi nuclear reactors were hit by an earthquake of magnitude 9.0 and flooded by the resulting tsunami, which caused a nuclear meltdown and release of radioactive materials. Over 100,000 people were evacuated from their homes due to the threat of radiation contamination.

In a large-scale radiological incident like this, emergency medical personnel need a rapid way to assess radiation exposure so they can identify the people who need immediate care. This radiation-dosimetry technology needs to be sensitive, accurate, fast and easy to use in a non-clinical setting.

Local scientists have developed a small, portable device that can quickly test the level of radiation exposure victims have suffered in such emergencies. This technology was developed by scientists from Berkeley Lab, Stanford University and several other institutions, as reported in a journal article recently published in Scientific Reports. The lead researchers were Dr. Shan Wang from Stanford University and Dr. Andrew Wyrobek from Berkeley Lab.

This new dosimetry device is a novel type of immunoassay. Immunoassays are chemical tests used to detect or measure the quantity of a specific substance in a body fluid sample using a reaction of the immune system. For example, a common immunoassay test for pregnancy measures the concentration of the human chorionic gonadotropin hormone in a woman’s blood or urine sample.

In order to measure a person’s radiation dose, the new device measures a blood sample for the concentration of particular proteins that change after radiation exposure. Scientists, including those in Wyrobek’s group, have previously identified these target proteins as excellent biological markers for radiation dosimetry. Basically, blood exposed to radiation has a special biochemical signature.

But scientists needed more than just target proteins. They also needed an accurate, sensitive way to quickly measure the proteins’ concentrations in a few drops of blood. So at the heart of the new device is a biochip developed by Wang’s group.

The biochip system relies on a sandwich structure where a target protein is trapped between a capture antibody and a detection antibody. The capture antibodies are immobilized on the surface of the biochip sensor. When a drop of blood is placed on the biochip, those antibodies capture the target proteins and the other proteins are washed away. Detection antibodies labeled with magnetic nanoparticles are then added, forming a sandwich structure that traps the target proteins. When an external oscillating magnetic field is then applied, the magnetic nanoparticles generate an electrical signal that is read out. This signal measures the number of magnetic nanoparticles bound to the surface, and this indicates the number of target proteins that have been trapped.

The researchers tested the biochip system using blood from mice that had been exposed to varying levels of radiation. Their novel immunoassay results were validated by comparing them to conventional ELISA immunoassay measurements. Overall the scientists demonstrated that the new biochip dosimetry system is fast, accurate, sensitive and robust. In addition, the whole system is the size of a shoebox so it is very portable.

“You add a drop of blood, wait a few minutes, and get results,” explained Wyrobek in a press release. “The chip could lead to a much-needed way to quickly triage people after possible radiation exposure.” Although the technology is still under development, hopefully it will be available before the next radiological accident or terrorist attack occurs.

For more information about this biochip system, check out my KQED Science blog.

Earworms: Those Intrusive Songs Stuck in Your Head

manic looking man listening to music on headphones
Photograph courtesy of John Hayes Photography via a Creative Commons license.

If you could hear inside my sister’s head, it would often sound like “Deck the halls with boughs of holly, Fa la la la la, la la la la.” For years, she has had this “earworm” – a song that plays in her head without control. Her mind acts like a broken record player that repeatedly plays the same song again and again, especially during quiet times when she is alone.

Having a song stuck in your head is a common experience. Research has shown that 92% of people experience earworms at least once a week. So it isn’t surprising that many myths exist about them. One common belief is that annoying music is more likely to become stuck.  Another is that certain music characteristics, such as simplicity and repetitiveness, cause songs to become intrusive. It is also thought that having earworms is more likely for certain types of people, including musicians and women. Finally, some people believe that interrupting a song creates a sense of incompleteness that leads the song to remain in the consciousness, making it more likely to become an earworm.

Researchers from the psychology department at Western Washington University have investigated these common beliefs about earworms, as reported in a journal article recently published in Applied Cognitive Psychology. They conducted five studies on earworms: an online survey of 299 participants, an experimental diary study of 16 participants, and three lab experiments with 89, 123 or 139 participants.

In the online survey, participants answered questions about their most recent earworm, general music experience and basic demographics. The other research studies used methods to induce earworms. During the lab experiments, participants evaluated three songs, completed a puzzle (maze, Sudoku or anagram), and then reported the extent to which they heard the three songs playing in their heads while completing the puzzle. They completed either an easy or difficult puzzle.

Although annoying songs like advertising jingles can become stuck in someone’s head, this appears to be relatively rare. Researchers found that people generally know and like the songs that become intrusive.

They also found that the intrusive songs are virtually unique to each individual, which suggests that lists of the most potent earworms are misleading. Earworms are mainly formed from recent and repeated exposure to a song, so they’re influenced by listening tastes. This is supported by a previous study that identified music exposure as the primary trigger for earworms, followed by memory triggers.

Researchers found no gender difference in how earworms were experienced. However, musicians did report having earworms more frequently than non-musicians, as did people who listen to music almost constantly.

The researchers also interrupted some of the songs that they played, expecting the interrupted songs to trigger earworms more frequently than the songs played to completion. However, no difference was observed due to song interruption.

Finally, they analyzed how participants responded to completing the different puzzle tasks. Researchers found that the best way to stop an earworm is to perform a verbal task: solve an anagram, have an engaging conversation or read an interesting book. But you don’t want the task to be too easy or too challenging, or your mind will wander and the earworm may return. I guess this means that I should give my sister some engrossing novels and a book of anagrams for her birthday?

For more information about earworms, check out my KQED Science blog.

Spotlight on Red Meat

photo of raw steaks
Photograph courtesy of IwateBuddy via Creative Commons licensing

Overall meat consumption continues to rise in the U.S., and 58% of the meat consumed is red meat. People in the U.S. eat 5 ounces of meat per day on average.

Eating a lot of red meat is known to contribute to heart disease, presumably due to the large amount of saturated fats and cholesterol in the meat. Or that is what we used to think. New research published in Nature Medicine indicates that the real culprit is a chemical in the red meat called L-carnitine. In a series of experiments on humans and mice, researchers found that L-carnitine is broken down by gut bacteria to produce trimethylamine-N-oxide (TMAO), which previous research has linked to heart and artery damage. TMAO alters how cholesterol is metabolized so less is eliminated from the body, allowing more cholesterol to deposit and harden into the artery walls.

But the researchers also found that frequent meat eaters produced significantly more TMAO than vegetarians after consuming the same amount of L-carnitine. For instance, L-carnitine supplements (250 mg) were given to 74 healthy volunteers, including 23 who were long-term vegetarians or vegans. The lab tests showed that consuming L-carnitine increased the level of TMAO in the blood, but meat eaters made far more TMAO than vegetarians or vegans.

Fecal studies also showed that meat eaters and vegetarians had different types of bacteria in their guts, and the meat eaters had more of the bacteria involved in breaking down L-carnitine into TMAO.

“The bacteria living in our digestive tracts are dictated by our long-term dietary patterns,” explained the lead researcher Dr. Stanley Hazen in a press release. “A diet high in carnitine actually shifts our gut microbe composition to those that like carnitine, making meat eaters even more susceptible to forming TMAO and its artery-clogging effects.”

The main food sources for carnitine are red meat and full-fat dairy products. It is also found in fish, poultry, tempeh, wheat, asparagus, avocados and peanut butter. L-carnitine is also commonly available as a dietary supplement, which is advertised as a weight loss and body building tool despite a lack of supporting scientific evidence. Plus L-carnitine is added to many energy drinks.

So eating all this L-carnitine is bad, right? Unfortunately it isn’t that simple.

Carnitine plays a vital and complex role in cardiac metabolism. Some people have diseases that cause a carnitine deficiency, so they need to take carnitine supplements. Studies have also shown that carnitine may help treat some heart conditions, such as angina, arrhythmias, heart attacks and heart failure. For instance, a meta-analysis review study in the Mayo Clinic Proceedings recently showed that taking L-carnitine supplements reduces your risk of ventricular arrhythmias by 65% and risk of angina by 40%, although no reduction in risk was seen for heart attacks and heart failure.

In general, scientific studies have shown both positive and negative effects on cardiac health from taking carnitine supplements. These discrepant findings may be due to differences in how the carnitine is administered and the dose. For instance, carnitine given by an intravenous or intramuscular injection would bypass the gut bacteria, so it may not form TMAO. Larger carnitine studies are needed, which also take into account the volunteers’ long-term diet and the bacteria ecosystem in their guts.

For more information about L-carnitine studies, check out my KQED Science blog.

Air Pollution Lurks Inside Your Home

photo of stir-frying
Photograph by kfisto via Creative Commons licensing.

How would you like a job that involves grocery shopping at Trader Joes with the company credit card and cooking dishes like stir-fry? This describes Tosh Hotchi’s job, but he isn’t a chef. He is part of a research team that studies how to build healthy efficient homes, including how to improve the quality of air inside a home through better ventilation. Hotchi is helping to study a major source of indoor pollutants – cooking.

When people think of air pollution, they usually picture a factory spewing a plume of toxic chemicals. But indoor air pollution causes significant health effects such as respiratory illness, asthma attacks, cancer and premature death. Californians spend over 45 billion dollars each year on these health impacts, according to a study by the California Air Resources Board.

Scientists at the Lawrence Berkeley National Laboratory (Berkeley Lab) have investigated which indoor air pollutants cause the greatest health consequences. In a paper published in Environmental Health Perspectives, they reported that fine particles with a diameter of 2.5 mm or less, formaldehyde and acrolein are the worst indoor contaminants for nonsmoking households.

Fine particulates are found indoors mainly due to cooking, burning candles or incense, and outdoor sources that leak inside. Formaldehyde is mainly emitted by materials used in home construction and furniture, such as particle board, paneling and foam insulation. Acrolein in the home is primarily from cooking, especially oils. All three of these contaminates also come from tobacco smoke.

“Think about what your putting in your home,” says Melissa Lunden, a Berkeley Lab staff engineer. “Most of us have to cook, but do you need the candles, incense and air fresheners? Freshening your air requires taking stuff out, not putting more stuff in.”

Berkeley Lab scientists are now looking for ways to improve indoor air quality, by developing better standards for residential buildings and new tests to measure these hazardous pollutants. Since cooking is a major source of indoor air pollutants, they have also evaluated the effectiveness of cooking exhaust hoods. Their study results showed that indoor air quality can be significantly improved by simply cooking on the back burners of your stove, using higher fan settings, and turning the fan on before you start cooking. Further research on cooking-induced pollutants is underway using a new demonstration kitchen to study real-life cooking conditions. During these studies, Tosh Hotchi’s stir-fry and cookies are just a happy bonus for his coworkers like Melissa Lunden.

For more information about indoor air pollution, check out my KQED Quest blog.

Nerve Stimulation May Prevent Migraines

Photograph of the Cefaly anti-migraine device, courtesy of STX-Medssprl via Creative Commons licensing
Photograph of Cefaly anti-migraine device, courtesy of STX-Med via Creative Commons license

While shopping for groceries at Trader Joes, suddenly your peripheral vision disappears. This could be frightening, but you know what is coming — a one-sided pulsating pain, sensitivity to light and noise, nausea, vomiting and seeing flashing lights. You quickly drive home and cancel your plans, because you have a migraine coming. You need to lie still in a dark quiet room for the next 24 hours.

Migraines affect about 30 million Americans. This means that one in four households in the US have at least one member impaired by migraines. Women are three times more likely to be migraine sufferers than men.

Unfortunately, there is currently no cure for migraines. A migraine diary can help identify the headache triggers to avoid. Medications can also help reduce the number of attacks or ease the symptoms, but these medications are often ineffective or cause unpleasant side effects.

Instead migraine sufferers might find relief from a new non-medicinal alternative, a device called a supraorbital transcutaneous stimulator (STS) that stimulates the nerves around the eyes and forehead. A study recently published in Neurology tested the safety and effectiveness of this STS device designed to prevent migraines.

Conducted by researchers in five specialized headache clinics in Belgium, this study was a randomized controlled trial that compared the STS device with an identical-looking sham device. Study participants were aged 18 to 65 who routinely experienced a minimum of two migraine attacks per month. None of the 67 participants had taken anti-migraine medications in the three months leading up to the study.

Both the STS and sham devices used a self-adhesive electrode placed on the forehead that buzzed identically during treatment. Only the STS devices delivered electrical impulses. The participants wore one of the devices for 20 minutes per day for 90 days.

The participants’ migraine diaries indicated that the number of migraine attacks dropped by at least half for 38% of the participants using the STS device, compared with 12% for those using the sham device. Although the severity of the migraines was not reduced, people using the STS device had fewer days with headache, fewer total migraine attacks, and used fewer pain relief medications each month. Most importantly, there were no adverse effects seen in either group.

The study concluded that treatment with a STS device is “effective and safe as a preventive therapy for migraine.” However, only 67 migraine sufferers have been studied and the use of this device was only examined for three months. Larger studies with longer-term treatment are needed to confirm that this STS device is safe and effective.

For more information about migraines and the STS device, check out my KQED Quest blog.

Dreaming of Sleep

woman laying in bed
Photograph courtesy of Wiros via a Creative Commons license.

You lay in bed, tossing and turning. Your body is exhausted, but your mind is racing with the day’s activities. Or worse yet, you’re stressing out about all the things on your to-do list for tomorrow.

Insomnia has become a major health concern worldwide with about 15% of the global population seeking relief with sleeping pills or tranquilizers. In the US, 60 million prescriptions for sleeping pills are issued each year. The most commonly prescribed type of sleeping pill is non-benzodiazepines, also called z-drugs — zaleplon (Sonata), zolpidem (Ambien), zopiclone (Imovane), and eszopiclone (Lunesta). However, a recent scientific journal article has raised some concerns about using these drugs.

Researchers from Harvard Medical School, the University of Connecticut and the University of London performed a quantitative statistical analysis of 13 studies on the effectiveness of z-drugs and their associated placebo response. They selected only randomized double-blind placebo-controlled trials, which means that neither the 4378 participants nor the researchers knew who was given the drug and who the placebo. They obtained the data from the US Food and Drug Administration, using both published and unpublished trials in order to avoid “publication bias.”  Their research results were published in the British Medical Journal on December 17, 2012.

This large, well-designed study found that the z-drugs helped participants fall asleep more quickly, as measured subjectively by the participants and by equipment in a sleep lab. However, half the effect of the drug was found to be due to a placebo response. Specifically, participants on average fell asleep in the lab only 22 minutes faster if taking the z-drug compared to the placebo. This has raised concern on whether the benefits of taking z-drugs are worth the risk of adverse side effects, which include daytime fatigue, memory loss, problems with balance, dependency, and an associated risk of an earlier death.

Of course, how quickly you fall asleep is only one symptom of insomnia. Other important measures are the total sleep time, number of awakenings, sleep quality, and time spent awake after sleep onset. Although the study looked at these other outcomes, unfortunately there was insufficient data to make firm conclusions on these factors.

Hopefully there will be further research to analyze the effectiveness of z-drugs on all aspects affecting sleep quality. In addition, the demonstrated importance of the placebo response suggests that more attention should be directed at psychological interventions for insomnia.

For more information about z-drugs, check out my KQED Quest blog.

Think Before You Drink Grapefruit Juice

photograph of grapefruit
Courtesy of dullhunk via Wikimedia Commons

You follow the directions on your medication carefully, always taking the pills with the correct frequency and with or without food as directed. But have you discussed with your doctor or pharmacist whether ingesting grapefruit could cause an unintentional drug overdose?

A drug is normally metabolized in the gastrointestinal tract, but a liver enzyme called cytochrome P450 3A4 (CYP3A4) deactivates much of the drug so the body only absorbs about half of it. This process is taken into account when a doctor prescribes the necessary dose.

However, grapefruit, grapefruit juice, Seville bitter oranges (used in marmalade), limes and pomelos naturally contain chemicals called furanocoumarins. These furanocoumarins inhibit the CYP3A4 enzymes, causing the gut to absorb much more of the drug at a potentially toxic level. Sweet oranges, such as navel or Valencia, do not contain furanocoumarins.

This grapefruit-medication interaction was discovered back in 1989 by David Bailey, Ph.D., a clinical pharmacologist at the Lawson Health Research Institute. However, Bailey recently released an expanded list of medications affected by grapefruit in the peer-reviewed Canadian Medical Association Journal. The number of drugs that interact with grapefruit has significantly increased to more than 85 as new drugs have come on the market. More importantly, 43 of these drugs could interact with grapefruit and lead to serious side effects, such as kidney damage, blood clots, respiratory depression, abnormal rapid heart beats (torsade de pointes) and sudden death.

So it is important to carefully read the information leaflet that comes with your medications, as well as discuss with your doctor or pharmacist how your diet may affect your medication.

For more information about a potential drug overdose caused by ingesting risky citrus, please check out my KQED Quest blog.

Dynamic Duo: Antibiotics and Probiotics

Photograph of antibiotics.
Photograph of antibiotics, courtesy of sparktography via Creative Commons license.

When your cold or flu virus turns into a bacterial infection, taking antibiotics can seem like a miracle. You often start feeling better after just a day or two. Antibiotics work by killing bacteria or by stopping bacteria from multiplying. Antibiotics quickly make you feel better because the drug kills the majority of the targeted bacteria very quickly.

However antibiotics also kill beneficial bacteria and induce negative side effects — most commonly diarrhea, upset stomach, and vaginal yeast infection. For instance, antibiotics cause about one out of three people to get diarrhea by disrupting the balance of the intestinal flora, a collection of bacteria and other microorganisms in the digestive tract. This can result in an overgrowth of the Clostridium difficile bacteria that causes diarrhea. Similarly, antibiotics can disrupt the vaginal flora and cause an overgrowth of Candida yeasts to cause a yeast infection.

Probiotics are live bacteria, yeasts and other microbes intended to maintain or restore the supply of beneficial bacteria in the body, particularly the stomach and intestines. Probiotics are found naturally in certain foods, including yogurt, aged cheeses, kefir, miso, tempeh, and fermented cabbage. Dietary supplements are another common source of probiotics.

The use of probiotics to reduce antibiotic-induced side effects is now becoming more widely accepted by the medical profession. A recent study published in the Journal of the American Medical Association supports taking probiotics with antibiotics. A team of researchers from southern California combined and analyzed the results of 63 randomized controlled trials of probiotics for the prevention or treatment of antibiotic-associated diarrhea. The 11811 men and women included in this large combined study took a placebo or probiotics supplement along with their antibiotics. The people who took the probiotics were 42% less likely to develop diarrhea than those taking the placebo.

However, further research is needed to determine the most effective probiotics and dose. Of course it is also important to limit your use of antibiotics, using them only for bacterial infections when necessary.

For more information about using probiotics with antibiotics, check out my KQED Quest website.

Should You Get a PSA Blood Test?

Photograph courtesy of Joint Base Lewis McChord via Creative Commons

My brother-in-law was seemingly the healthiest person I knew. He never even got a cold, so he rarely saw the doctor. Luckily he got a complete checkup when he turned 50, because it turned out that he had aggressive prostate cancer. Standard screening, to find prostate cancer in people who don’t have symptoms, allowed him to be treated in time.

Standard prostate cancer screening consists of a digital (finger) rectal exam to feel for prostate abnormalities and a simple blood test that measures the amount of prostate-specific antigen (PSA) in the blood. PSA is a protein produced by the prostate gland that is present in small quantities for healthy men, but it’s generally evaluated for men with prostate cancer and other prostate disorders. The goal of PSA screening is to detect prostate cancer early, so it is easier to treat and more likely to be cured.

So why has PSA screening recently become so controversial when it’s just a simple blood test? The main issue is that PSA screening isn’t good at distinguishing between aggressive life-threatening prostate cancer and slow-growing prostate cancer that may never spread. So it may lead to unnecessary side effects from overtreatment of slow-growing prostate cancer, including a risk of incontinence and impotence.

This controversy escalated in May 2012 when a government panel of health experts called the U.S. Preventive Services Task Force (USPSTF) recommended against PSA-based screening for prostate cancer for men of any age, stating that the benefits of screening don’t outweigh the harms of overtreatment.

The USPSTF based its recommendation primarily on the two largest published randomized clinical trials that evaluated the effectiveness of PSA screening. The first is the U.S. Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial in which 76,685 men aged 55 to 74 years were randomly assigned to receive either annual PSA screening or “usual care.” The study found that slightly more prostate cancers were found in the PSA screened group, but the number of people that died from prostate cancer were about the same for both groups. Hence, it raised the question of whether men were harmed from overtreatment of cancers that weren’t life threatening.  However, this PLCO study is inherently flawed because 52% of the “usual care” control group also received PSA screening and 40% of the study participants received PSA screening before enrollment in the trial. Since so many men in the “usual care” control group received PSA screening, it’s not surprising that the prostate cancer mortality rates were the same for both groups.

The USPSTF also based its recommendation on the European Randomized Study of Screening for Prostate Cancer (ERSPC) that randomly assigned 162,243 men aged 55 to 69 years to either PSA screening once every 4 years or an unscreened control group. After correcting for patients that did not follow the protocol-prescribed screening procedures, the ERSPC found that PSA screening actually reduced the risk for dying of prostate cancer by 31%. Many argue that this demonstrates that PSA screening has a significant benefit, so it’s unclear how the USPSTF considered these results in their benefit to harm analysis.

An ad hoc group of nationally recognized prostate cancer medical experts have argued against the USPSTF recommendations. They state, “We believe that eliminating reimbursement for PSA testing would take us back to an era when prostate cancer was often discovered at advanced and incurable stages.”

A journal article published in the July 2012 issue of Cancer supports the view of this ad hoc group. Researchers at the University of Rochester Medical Center used data from the Surveillance, Epidemiology and End Results Program to estimate the total number of men in the current U.S. population who would have metastatic prostate cancer at initial diagnosis if PSA screening weren’t used. Such metastatic prostate cancer is usually rapidly fatal with a median survival of less than 1 yr to 2.6 years, depending on age.  The study found that there would have been 25,000 men presenting with metastatic disease in 2008 in the absence of PSA-screening, instead of the 8,000 men that were actually observed using PSA-screening.

So the uncertainty and controversy about PSA screening continues despite extensive research. Since I work in the field of prostate cancer research, friends and family members have asked my opinion. It seems to me that the new screening guidelines against PSA testing assume that ignorance is less stressful than having faith in your doctor; specifically, it’s better to not even perform a simple PSA blood test because patients with low PSA levels are often over-treated. Why not just change how to treat patients with low PSA levels and repeat the blood test in 6 months to a year to see how quickly the PSA level rises — since prostate cancer is more likely to cause a rapid rise in PSA levels? Is this common practice of “watchful waiting” by your doctor really more stressful than not having the blood test at all? For some, that simple blood test could also indicate that you have aggressive prostate cancer that has spread and needs immediate treatment.

For more information about PSA screening, check out my KQED Quest blog.

Stem Cells Cause Clogged Arteries

illustration of how the newly discovered vascular stem cells can become smooth muscle, fat, cartilage or bone cells.
Within the walls of blood vessel are smooth muscle cells and newly discovered vascular stem cells. These stem cells are able to differentiate into smooth muscle, fat, cartilage and bone cells. (Song Li illustration)

Odds are that you know someone who’s had a heart attack. If you’re like me, you know many. One American suffers a coronary event every 25 seconds and about every minute someone dies from one.

Doctors thought they understood artery-hardening diseases that lead to heart attacks, strokes and death. But these theories have been contradicted by new research performed at the University of California, Berkeley. According to a new study published in Nature Communications, a previously unknown type of stem cell is actually the underlying cause for clogged arteries.

Researchers analyzed cells from blood vessels of transgenic mice and humans. They were able to trace the lineage of the cells that rapidly reproduced to cause a build up of fibrous scar tissue in the vessel walls. Current theories predicted these would be smooth muscle cells but instead they were a newly discovered type of stem cell.

Specifically they determined that the culprit behind clogged arteries are multipotent vascular stem cells that can develop into various specialized cells – smooth muscle, nerve, cartilage, bone and fat cells. This explains how arteries can calcify and harden, since the stem cells can form bone and cartilage.

If this research is verified in animals and humans by other research groups, this could lead to new therapies.

For more information about this research, check out my KQED Quest blog.