All Good Read

The itchy wool sweater explained

Johns Hopkins researchers have uncovered strong evidence that mice have a specific set of nerve cells that signal itch but not pain, a finding that may settle a decades-long debate about these sensations, and, if confirmed in humans, help in developing treatments for chronic itch, including itch caused by life-saving medications.
At the heart of their discovery is a type of sensory nerve cell whose endings receive information from the skin and relay it to other nerves in the spinal cord, which then coordinates a response to the stimulus. Published online Dec. 23 in Nature Neuroscience, a report on the research suggests that even when the itch-specific nerve cells receive stimuli that are normally pain-inducing, the message they send isn’t “That hurts!” but rather “That itches!”
Pain and itch are both important sensations that help organisms survive. And pain is arguably more important because it tells us to withdraw the pained body part in order to prevent tissue damage. But itch also warns us of the presence of irritants, as in an allergic reaction. However, “when either of these sensations continues for weeks or months, they are no longer helpful. We even see patients stop taking life-saving medications because they cause such horrible itchiness all over,” says Xinzhong Dong, a Howard Hughes early career scientist and associate professor of neuroscience at the Institute of Basic Biomedical Sciences at the Johns Hopkins University School of Medicine. “And sometimes when we try to suppress chronic pain, with morphine for example, we end up causing chronic itchiness. So the two sensations are somehow related, and this study has begun to untangle them,” he says.

Babies in womb learn language from their mothers

Babies only hours old are able to differentiate between sounds from their native language and a foreign language, scientists have discovered. The study indicates that babies begin absorbing language while still in the womb, earlier than previously thought.
Sensory and brain mechanisms for hearing are developed at 30 weeks of gestational age, and the new study shows that unborn babies are listening to their mothers talk during the last 10 weeks of pregnancy and at birth can demonstrate what they've heard.
"The mother has first dibs on influencing the child's brain," said Patricia Kuhl, co-author and co-director of the Institute for Learning & Brain Sciences at the University of Washington. "The vowel sounds in her speech are the loudest units and the fetus locks onto them."
Previously, researchers had shown that newborns are born ready to learn and begin to discriminate between language sounds within the first months of life, but there was no evidence that language learning had occurred in utero.
"This is the first study that shows fetuses learn prenatally about the particular speech sounds of a mother's language," said Christine Moon, lead author and a professor of psychology at Pacific Lutheran University in Tacoma, Wash. "This study moves the measurable result of experience with speech sounds from six months of age to before birth."

Aerobic, not resistance, better for quick weight loss

A new study led by North Carolina researchers has found that when it comes to weight- and fat loss, aerobic training is better than resistance training. The study is believed to the largest randomized trial to directly compare changes in body composition induced by comparable amounts of time spent doing aerobic and resistant training, or both in combination, among previously inactive overweight or obese non-diabetic adults.
The study is entitled “Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults” (http://bit.ly/Rs7Rp4). It is published in the December 2012 edition of the Journal of Applied Physiology published by the American Physiological Society.
Methodology
A total of 234 previously sedentary overweight or obese males and females, age 18-70 years of age, were enrolled in one of three eight-month supervised protocols: aerobic training (AT), resistance training (RT), or a combination (AT/RT). Of the total, 119 participants completed the trials and had complete data for the variables of interest in the article.

Smoking affects heart surgery outcome even after quitting

Smoking cessation even a year prior to coronary artery bypass grafting (CABG) surgery does not fully normalize the changes smoking has made to the saphenous (leg) veins used for the surgery and may lead to later graft failure, according to a study published in the January 2013 issue of The Annals of Thoracic Surgery.
Sun Yongxin, MD and colleagues from Zhongshan Hospital at Fudan University in Shanghai, China, analyzed heart surgery outcomes in 208 patients undergoing elective CABG surgery. After dividing the patients into six groups based on the current quantity smoked and previous smoking status, the researchers found that heavy smoking noticeably increased matrix metalloproteinase enzyme levels in the saphenous vein. These enzymes have been linked to vein graft failure.
The researchers also found that while dysregulation of enzymes may gradually normalize after smoking cessation, a noticeable vein recovery needs at least 6 months, and vein enzymes do not completely return to normal levels even after 1 year.
“Although recovery after smoking cessation appears somewhat disappointing, it illustrates exactly the importance of prompt smoking cessation for patients who will receive CABG,” the researchers wrote.

Hydrogen peroxide vapor improves hospital disinfection

Infection control experts at The Johns Hopkins Hospital have found that a combination of robot-like devices that disperse a bleaching agent into the air and then detoxify the disinfecting chemical are highly effective at killing and preventing the spread of multiple-drug-resistant bacteria, or so-called hospital superbugs.
A study report on the use of hydrogen peroxide vaporizers -- first deployed in several Singapore hospitals during the 2002 outbreak of severe acute respiratory syndrome, or SARS, and later stocked by several U.S. government agencies in case of an anthrax attack - is to be published Jan. 1 in the journal Clinical Infectious Diseases.
In the study, the Johns Hopkins team placed the devices in single hospital rooms after routine cleaning to disperse a thin film of the bleaching hydrogen peroxide across all exposed hospital equipment surfaces, as well as on room floors and walls. Results showed that the enhanced cleaning reduced by 64 percent the number of patients who later became contaminated with any of the most common drug-resistant organisms. Moreover, researchers found that protection from infection was conferred on patients regardless of whether the previous room occupant was infected with drug-resistant bacteria or not.

Scientists home in on cause of osteoarthritis pain

Researchers at Rush University Medical Center, in collaboration with researchers at Northwestern University, have identified a molecular mechanism central to the development of osteoarthritis (OA) pain, a finding that could have major implications for future treatment of this often-debilitating condition.
“Clinically, scientists have focused on trying to understand how cartilage and joints degenerate in osteoarthritis. But no one knows why it hurts,” said Dr. Anne-Marie Malfait, associate professor of biochemistry and of internal medicine at Rush, who led the study. An article describing the research was published in the December 11 print version of the Proceedings of the National Academy of Sciences.
Joint pain associated with OA has unique clinical features that provide insight into the mechanisms that cause it. First, joint pain has a strong mechanical component: It is typically triggered by specific activities (for example, climbing stairs elicits knee pain) and is relieved by rest. As structural joint disease advances, pain may also occur in rest. Heightened sensitivity to pain, including mechanical allodynia (pain caused by a stimulus that does not normally evoke pain, such as lightly brushing the skin with a cotton swab), and reduced pain-pressure thresholds are features of OA.

Practice makes perfect when it comes to losing weight

Losing weight and saving money are perenially the top New Year’s resolutions made by many Americans. But both require behavioral changes and a certain amount of discipline.
“People need a motivation to lose weight and the new year is an opportunity to start fresh,” said Dr. Jessica Bartfield, internal medicine and medical weight-loss specialist at Gottlieb Memorial Hospital, part of the Loyola University Health System.
“Maybe it was the shock of seeing oneself in recent holiday photos, or not being able to fit into desired party attire that causes a vow to lose weight, and for many more it is a medical event such as a heart attack, the threat of diabetes or high blood pressure,” she said.
Bartfield is part of the Loyola Center for Metabolic Surgery & Bariatric Care that offers non-surgical as well as surgical weight loss programs for patients. Patients in both programs benefit from a dedicated team of medical professionals in psychology, nutrition, exercise physiology and more with an expertise in bariatrics.
“Behavior change is the cornerstone of healthy, successful weight loss and it takes about three months to establish a new behavior,” said Bartfield. “Just as you learn to play a musical instrument from a skilled teacher, you need to learn how to lose weight from professionals. You need to practice and make mistakes until you get it right. At Loyola, a team of tried-and-true medical experts can teach you the skills you need to achieve and maintain behavior change.”

Piranha kin wielded force that T.Rex would have admired

Taking into consideration its size, an ancient relative of piranhas weighing about 20 pounds delivered a bite with a force more fierce than prehistoric whale-eating sharks, the four-ton ocean-dwelling Dunkleosteus terrelli and – even – Tyrannosaurus rex.
Besides the force of the bite, Megapiranha paranensis appears to have had teeth capable of shearing through soft tissue the way today's piranhas do, while also being able to pierce thick shells and crack armoring and bones, according to Stephanie Crofts, a University of Washington doctoral student in biology.
"If our calculations are correct, Megapiranha was probably a bone-crushing predator taking bites of anything and everything," she said. Crofts is co-author of "Mega-Bites: Extreme jaw forces of living and extinct piranhas," published Dec. 13 in the online journal Scientific Reports.
The bite force of Megapiranha, which lived 10 million years ago, was extrapolated from the first field measurements of the biting force of Earth's largest piranha today, Serrasalmus rhombeus or black piranha. One 2 ½ pound fish delivered a bite with a force of 320 newtons, or about 72 pounds, which is 30 times its body weight. The force is nearly three times greater than the bite force of an equivalent size American alligator.

Starvation did not cause saber toothed tiger's extinction

In the period just before they went extinct, the American lions and saber-toothed cats that roamed North America in the late Pleistocene were living well off the fat of the land.
That is the conclusion of the latest study of the microscopic wear patterns on the teeth of these great cats recovered from the La Brea tar pits in southern California. Contrary to previous studies, the analysis did not find any indications that the giant carnivores were having increased trouble finding prey in the period before they went extinct 12,000 years ago.
The results, published on Dec. 26 in the scientific journal PLOS ONE, contradicts previous dental studies and presents a problem for the most popular explanations for the Megafaunal (or Quaternary) extinction when the great cats, mammoths and a number of the largest mammals that existed around the world disappeared.
“The popular theory for the Megafaunal extinction is that either the changing climate at the end of the last Ice Age or human activity – or some combination of the two – killed off most of the large mammals,” said Larisa DeSantis, assistant professor of earth and environmental sciences at Vanderbilt, who headed the study.

New MRI method may help diagnose dementia

A new way to use MRI scans may help determine whether dementia is Alzheimer’s disease or another type of dementia, according to new research published in the December 26, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology.
Alzheimer’s disease and frontotemporal lobar degeneration (FTLD) often have similar symptoms, even though the underlying disease process is much different.
“Diagnosis can be challenging,” said study author Corey McMillan, PhD, of the Perelman School of Medicine and Frontotemporal Degeneration Center at the University of Pennsylvania and a member of the American Academy of Neurology. “If the clinical symptoms and routine brain MR are equal, an expensive positron emission tomography (PET) scan might be needed. Or, a lumbar puncture, which involves inserting a needle into the spine, would be needed to help make the diagnosis. Analysis of the cerebrospinal fluid gives us reliable diagnostic information, but this is not something patients look forward to and is also expensive. Using this new MRI method is less expensive and definitely less invasive.”