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‘CSI’ conservation uses tiger spit and conch fritters

Thu, 2019-04-18 20:30

Scientists have come up with a new way to collect DNA from endangered species—extract it from degraded and left-behind materials, including feces, saliva, and even food products.

The near impossibility of collecting DNA samples from rare and elusive animals has hobbled wildlife detectives aiming to protect these endangered species. The researchers say their proof of concept, which appears in Methods in Ecology and Evolution, could revolutionize conservation approaches and policies worldwide.

“It’s CSI meets conservation biology,” says coauthor Dmitri Petrov, professor in the School of Humanities and Sciences at Stanford University.

Looming extinctions

The specter of extinction hangs over more than a quarter of all animal species, according to the best estimate of the International Union for Conservation of Nature, which maintains a list of threatened and extinct species. Conservationists have documented extreme declines in animal populations in every region of Earth.

“Conservation needs answers fast, and our research was not providing them fast enough.”

Helping species recover often depends on collecting DNA samples, which can reveal valuable information about details including inbreeding, population history, natural selection, and large-scale threats such as habitat destruction and illegal wildlife trade.

However, current approaches tend to require relatively large amounts of DNA or expensive and often inefficient strategies for extracting the material. Getting meaningful information rapidly from lower-concentration, often degraded and contaminated DNA samples requires expensive and specialized equipment.

Tigers and conchs

A solution may lie in an ongoing collaboration between Stanford’s Program for Conservation Genomics, including the labs of Petrov and coauthors Elizabeth Hadly and Stephen Palumbi, and India’s National Centre for Biological Sciences, including the lab of coauthor Uma Ramakrishnan, a molecular ecologist and former Fulbright faculty fellow at Stanford.

“I have been working on tiger conservation genetics for over a decade, but have been frustrated at how slow and unreliable the process of generating genetic data can be,” Ramakrishnan says. “Conservation needs answers fast, and our research was not providing them fast enough.”

The researchers looked at endangered wild tigers in India and overfished Caribbean queen conchs, examining tiger feces, shed hair, and saliva found on killed prey, as well as fried conch fritters purchased in US restaurants. All of the samples were too impure, mixed, or degraded for conventional genetic analysis.

“Our goal was to find extremely different species that had strong conservation needs, and show how this approach could be used generally,” says Palumbi, professor of marine biology. “The King of the Forest—tigers—and Queen of the Caribbean—conch—were ideal targets.”

Tiny bits of DNA

Together, the team improvised a new approach, using a sequencing method that amplifies and reads small bits of DNA with unique differences in each sample. Doing this simultaneously across many stretches of DNA in the same test tubes allowed the researchers to keep the total amount of DNA needed to a minimum.

Making the procedure specific to tiger and conch DNA allowed for the use of samples contaminated with bacteria or DNA from other species.

The technology proved highly effective at identifying and comparing genetic characteristics. For example, the method worked with an amount of tiger DNA equivalent to about one-one-hundred-thousandth the amount of DNA in a typical blood sample. The method had a higher failure rate in conchs because the researchers did not have whole genomes at their disposal.

The approach’s effectiveness, speed and affordability—implementation could cost as little as $5 per sample—represents a critical advance for wildlife monitoring and forensics, field-ready testing, and the use of science in policy decisions and wildlife trade, the researchers say.

“It is easy to implement and so can be done in labs with access to more or less basic equipment,” says coauthor Meghana Natesh of the National Centre for Biological Sciences and Sastra University in India. “If a standard procedure is followed, the data generated should be easy to share and compare across labs. So monitoring populations across states or even countries should be easier.”

The scientists have made their methods freely available. “We are working to expand the method so that it can identify other species and other characteristics, such as diet and pathogens,” Hadly says.

The Wildlife Conservation Trust, the US Department of State, the Wellcome Trust / DBT India Alliance, the Summit Foundation, and the Smithsonian Institution funded the work, which appears in
Methods in Ecology and Evolution.

Source: Stanford University

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Rain on other side of the planet foreshadows California heat

Thu, 2019-04-18 19:50

When heavy rain falls over the Indian Ocean and Southeast Asia and the eastern Pacific Ocean, it is a good indicator that temperatures in central California will reach 100°F in four to 16 days, according to new research.

Heat waves are common in California’s Central Valley, a 50-mile-wide oval of land that runs 450 miles from just north of Los Angeles up to Redding. The valley is home to half of the nation’s tree fruit and nut crops, as well as extensive dairy production, and heat waves can wreak havoc on agricultural production. The dairy industry had a heat wave-induced economic loss of about $1 billion in 2006, for instance. The ability to predict heat waves and understand what causes them could inform protective measures against damage.

“We want to know more about how extreme events are created,” says corresponding author Richard Grotjahn, professor in the land, air, and water resources department at the University of California, Davis.

“We know that such patterns in winter are sometimes linked with areas of the tropics where thunderstorms are enhanced. We wondered if there might be similar links during summer for those heat waves.”

The scientists analyzed the heat wave data from June through September from 1979 to 2010. Fifteen National Climatic Data Center stations located throughout the valley collected the data. From these data, the researchers identified 24 heat waves. They compared these instances to the phases of a large, traveling atmospheric circulation pattern called the Madden-Julian Oscillation, or MJO.

The MJO manifests as heavy rain that migrates across the tropical Indian and then Pacific oceans, and researchers have shown that it influences winter weather patterns.

“It’s well known that tropical rainfall, such as the MJO, has effects beyond the tropics,” says the paper’s first author Yun-Young Lee of the Asia-Pacific Economic Cooperation Climate Center in Busan, South Korea. “So a question comes to mind: Is hot weather in the Central California Valley partly attributable to tropical rainfall?”

Lee and Grotjahn found that, yes, enhanced rainfall in the tropics preceded each heat wave in specific and relatively predictable patterns. They also found that hot weather in the valley is most common after more intense MJO activity in the eastern Pacific Ocean, and next most common after strong MJO activity in the Indian Ocean.

“The more we know about such associations to large-scale weather patterns and remote links, the better we can assess climate model simulations and therefore better assess simulations of future climate scenarios,” Grotjahn says.

The National Science Foundation, the National Aeronautics and Space Administration, the Department of Energy Office of Science, the United States Department of Agriculture’s National Institute of Food and Agriculture, and the APEC Climate Center in the Republic of Korea funded the research.

The work appears in Advances in Atmospheric Sciences.

Source: UC Davis

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We finally know how general anesthesia works

Thu, 2019-04-18 19:44

In a new study,researchers found that to knock you out, different anesthesia drugs hijack the neural circuitry that makes you fall sleep.

The discovery of general anesthesia 170 years ago was a medical miracle, enabling millions of patients to undergo invasive, life-saving surgeries without pain.

General anesthesia drugs induce unconsciousness by activating a tiny cluster of cells at the base of the brain called the supraoptic nucleus (shown in red), while the rest of the brain remains in a mostly inactive state (blue). (Credit: Duke)

For the study, which appears in Neuron, researchers traced this neural circuitry to a tiny cluster of cells at the base of the brain responsible for churning out hormones to regulate bodily functions, mood, and sleep.

The finding is one of the first to suggest a role for hormones in maintaining the state of general anesthesia, and provides valuable insights for generating newer drugs that could put people to sleep with fewer side effects.

Ever since the first patient went under general anesthesia in 1846, scientists have tried to figure out exactly how it works. The prevailing theory was that many of these drugs tamp down the brain’s normal activities, resulting in the inability to move or feel pain.

Similar theories revolved around sleep, the sister state to general anesthesia. However, research over the last decade has shown that sleep is a more active process than previously recognized, with entire sets of neurons clocking in to work while you catch your Z’s.

Fan Wang, a professor of neurobiology at Duke University School of Medicine, and Li-Feng Jiang-Xie, a graduate student in her laboratory, wondered whether the predominant view of general anesthesia was also one-sided.

“Perhaps rather than simply inhibiting neurons, anesthetics could also activate certain neurons in the brain,” says Jiang-Xie.

To test their new theory, Jiang-Xie and Luping Yin, a postdoctoral fellow in the Wang lab, put mice under general anesthesia with several different but commonly used drugs. Then they used molecular markers to track down the neurons commonly activated by the anesthetics.

They found a cluster of actively firing neurons buried in a tiny brain region called the supraoptic nucleus, known to have leggy projections that release large amounts of hormones like vasopressin directly into the bloodstream.

“Most of the anesthesia-activated cells were a kind of hybrid cell that connects the nervous system and the endocrine system,” says Jiang-Xie. “That took us by surprise and led us into unexplored territory for understanding the neural pathways of general anesthesia.”

Next, the researchers tapped a sophisticated technique developed in the Wang lab to turn on or off this specialized group of cells with chemicals or light. When they switched on the cells in mice, the animals stopped moving and fell into a deep slumber called slow wave sleep, typically associated with unconsciousness.

Then the research team killed off this group of cells. The mice continued to move around, unable to fall asleep.

Finally, the researchers performed similar experiments on mice under general anesthesia. They found that artificially pre-activating the neuroendocrine cells made the mice stay under general anesthesia for longer periods of time. Conversely, when they silenced these cells, the mice woke up from anesthesia more easily.

The study also revealed a previously unexpected role of the brain’s hormone-secreting cells in promoting deep sleep.

“Many people, particularly those with Alzheimer’s disease, have difficulty falling to sleep, yet current medications have troublesome side effects,” says Yin. “If we can find ways to manipulate this neural circuitry, perhaps by targeting hormones or small peptides, then it could lead to the development of better sleeping pills.”

The W.M Keck Foundation, the Brain Research Foundation, the National Institutes of Health, and a Human Frontier Science Fellowship funded the work.

Source: Duke University

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System restores some pig brain function hours after death

Thu, 2019-04-18 19:33

Researchers restored circulation and cellular activity in a pig’s brain four hours after its death, the team reports.

The finding challenges long-held assumptions about the timing and irreversible nature of the cessation of some brain functions after death.

Researchers isolated the brain of a postmortem pig from a meatpacking plant and circulated a specially designed chemical solution. They observed many basic cellular functions once thought to cease seconds or minutes after oxygen and blood flow cease, the scientists report.

“The intact brain of a large mammal retains a previously under-appreciated capacity for restoration of circulation and certain molecular and cellular activities multiple hours after circulatory arrest,” says senior author Nenad Sestan, professor of neuroscience, comparative medicine, genetics, and psychiatry at Yale University.

Immunofluorescent stains for neurons (green), astrocytes (red), and cell nuclei (blue) in a region of the hippocampus of a pig’s brain left untreated 10 hours after death (left) or subjected to perfusion with the BrainEx technology. Ten hours postmortem, neurons and astrocytes undergo cellular disintegration unless the BrainEx system salvages them. (Credit: Stefano G. Daniele & Zvonimir Vrselja; Sestan Laboratory; Yale School of Medicine)

Researchers also stress, however, that the brain lacked any recognizable global electrical signals associated with normal brain function.

“At no point did we observe the kind of organized electrical activity associated with perception, awareness, or consciousness,” says co-first author Zvonimir Vrselja, associate research scientist in neuroscience.

“Clinically defined, this is not a living brain, but it is a cellularly active brain.”

The nature of death

Scientists usually consider cellular death within the brain a swift and irreversible process. Cut off from oxygen and a blood supply, the brain’s electrical activity and signs of awareness disappear within seconds, while energy stores are depleted within minutes. Current understanding maintains that a cascade of injury and death molecules activate, leading to widespread, irreversible degeneration.

However, researchers in Sestan’s lab, whose research focuses on brain development and evolution, observed that the small tissue samples they worked with routinely showed signs of cellular viability, even when the tissue was harvested multiple hours postmortem.

Intrigued, they obtained the brains of pigs processed for food production to study how widespread this postmortem viability might be in the intact brain. Four hours after the pig’s death, they connected the vasculature of the brain to circulate a uniquely formulated solution they developed to preserve brain tissue, utilizing a system they call BrainEx. They found the system preserved neural cell integrity, and restored certain neuronal, glial, and vascular cell functionality.

Why it matters

The new system can help solve a vexing problem—the inability to apply certain techniques to study the structure and function of the intact large mammalian brain—which hinders rigorous investigations into topics like the roots of brain disorders, as well as neuronal connectivity in both healthy and abnormal conditions.

“Previously, we have only been able to study cells in the large mammalian brain under static or largely two-dimensional conditions utilizing small tissue samples outside of their native environment,” says co-first author Stefano G. Daniele, an MD/PhD candidate.

“For the first time, we are able to investigate the large brain in three dimensions, which increases our ability to study complex cellular interactions and connectivity.”

While the advance has no immediate clinical application, the new research platform may one day be able to help doctors find ways to help salvage brain function in stroke patients, or test the efficacy of novel therapies targeting cellular recovery after injury, the authors say.

“This line of research holds hope for advancing understanding and treatment of brain disorders and could lead to a whole new way of studying the postmortem human brain,” says Andrea Beckel-Mitchener, chief of functional neurogenomics at the NIH’s National Institute of Mental Health, which co-funded the research.

Ethical standards

The researchers says that it is unclear whether this approach can be applied to a recently deceased human brain. The chemical solution used lacks many of the components natively found in human blood, such as the immune system and other blood cells, which makes the experimental system significantly different from normal living conditions. However, the researchers stress that any future study involving human tissue or possible revival of global electrical activity in postmortem animal tissue should be done under strict ethical oversight.

“Restoration of consciousness was never a goal of this research,” says coauthor Stephen Latham, director of Yale’s Interdisciplinary Center for Bioethics. “The researchers were prepared to intervene with the use of anesthetics and temperature-reduction to stop organized global electrical activity if it were to emerge. Everyone agreed in advance that experiments involving revived global activity couldn’t go forward without clear ethical standards and institutional oversight mechanisms.”

There is an ethical imperative to use tools developed by the Brain Initiative to unravel mysteries of brain injuries and disease, says Christine Grady, chief of the Department of Bioethics at the NIH Clinical Center.

“It’s also our duty to work with researchers to thoughtfully and proactively navigate any potential ethical issues they may encounter as they open new frontiers in brain science,” she says.

The research appears in Nature. The National Institutes of Health’s BRAIN Initiative funded the research.

Source: Yale University

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Can ginkgo biloba seeds fight skin infections?

Thu, 2019-04-18 13:05

Extracts from the seeds of the Ginkgo biloba tree show antibacterial activity on pathogens that can cause skin infections such as acne, psoriasis, dermatitis, and eczema, a new study finds.

The findings show that the extracts inhibit the growth of Cutibacterium acnes, Staphylococcus aureus, and Streptococcus pyogenes.

A nearly 200-year-old copy of a 16th-century text on traditional Chinese medicine, the Ben Cao Gang Mu, guided the researchers in their experiments.

“It was like blowing the dust off knowledge from the past and rediscovering something that had been there all along,” says co-first author of the paper Xinyi (Xena) Huang.

Huang, a native of China, began the project for her senior thesis as a biology major at Emory University. She is now a student at the University of Maryland School of Pharmacy.

‘Complex chemistry’

“To the best of our knowledge, this is the first study to demonstrate the antibacterial activity of ginkgo seeds on skin pathogens,” says Cassandra Quave, senior author of the paper and assistant professor at Emory’s Center for the Study of Human Health and the dermatology department at the School of Medicine.

“This paper is just one more example of how much we still have to learn about the pharmacological potential of the complex chemistry of plants.”

Quave is an ethnobotanist, studying how indigenous people use plants in their healing practices, to uncover promising candidates for new drugs.

“Our results give validity to the use of ginkgo seeds as a topical antimicrobial as prescribed in this 16th-century text,” says co-first author Francois Chassagne, a pharmacist in the Quave lab.

Many hurdles remain, he adds, before scientists can consider ginkgo seed extracts for use in a modern-day medical context. In its concentrated form, the main compound that a statistical analysis identified as likely responsible for the antibacterial activity, ginkgolic acid C15:1, has been demonstrated to have skin toxicity.

“One possible strategy in the search for new antibiotics would be to investigate ways to modify the structure of the particular ginkgolic acid tied to the antibacterial activity, to try to improve its efficacy and also to reduce its toxicity to human skin cells,” Chassagne says.

The ginkgo biloba, which is native to China, is one of the oldest tree species, going back at least 270 million years. The tree has distinctive fan-shaped leaves and a long history in traditional Chinese medicine.

Modern-day researchers have studied ginkgo extensively in search of medical benefits for everything from memory enhancement to macular degeneration, but there is still “no conclusive evidence that ginkgo is helpful for any health condition,” according to the web page of the National Institutes of Health’s National Center for Complementary and Integrative Health. Most previous studies have focused on the ginkgo leaves.

A seed of inspiration

During her first year at Emory, Huang began volunteering in the Emory Herbarium, where she processed medicinal herbs that Quave collected in the Mediterranean. She eventually joined the Quave lab, due to her interest in pharmacy.

When walking across campus, pondering what to focus on for her senior thesis, a ginkgo tree caught Huang’s eye. She knew that the tree was used in traditional Chinese medicine, although she did not know any details, so she decided to research it.

Huang’s interest grew when she learned that Emory has an 1826 version of the Ben Cao Gang Mu, or Compendium of Materia Medica. Considered the most comprehensive book on traditional Chinese medicine, Li Shi-zhen compiled and wrote the book in the 16th century during the heyday of the Ming Dynasty. The original compendium is vast, encompassing dozens of volumes, but Huang had only seen greatly condensed versions sold in Chinese bookstores.

The copy Huang read resides in the Candler School of Theology’s Pitts Theology Library. The 1826 version passed at one stage through a London book dealer. The unnumbered pages contain block-printed in Chinese characters, but at some point someone rebound them into 10 volumes with covers labeled in English.

The Ben Cao Gang Mu arrived at Emory as part of the university’s purchase of more than 200,000 volumes from Hartford Theological Seminary in 1975.

“At the time, it was the largest transfer of a book collection ever between academic libraries,” says Brandon Wason, above, curator of archives and manuscripts at Pitts Theology Library.

Touching history

Huang never imagined she would be touching such an old copy of the Ben Cao Gang Mu.

“You can feel the history in it,” she says. “The paper is so yellow, thin and fragile that I was afraid I would break the pages as I was turning them.”

In a volume labeled “Grains, Vegetables, Fruits,” Huang found references to the uses of ginkgo, written in an engaging, narrative style. The book described 17 traditional uses for the seed, including eight for skin disorders such as chapped hands and feet, rosacea, crab louse-induced itchiness, dog-bit wound abscesses, and pustules.

Li Shi-Zhen recommended preparing a paste of ground up seeds mixed with rice wine or other alcohol, or by immersing the crushed seeds in rape seed oil. The paste could then be applied to the affected area.

“I was surprised because I had never thought about doing anything with gingko seeds except eating them,” Huang says. “I remember the first time I tasted them was in Cantonese soup. The seed turns an unforgettable bright yellow when it’s cooked. The flavor is really distinct—a little bit bitter but also sweet. They’re good, but my parents warned me not to eat more than five at a time.”

The Ben Cao Gang Mu, she learned as she read it, also advised limiting consumption of the seeds.

The past and the present

A previous study found that ginkgo seed coats demonstrated antibacterial activity against some intestinal bacterial pathogens. And ginkgo leaves have shown antibacterial activity on both some intestinal bacteria and on the skin pathogen S. aureus.

Huang, however, wanted to test the information she had gleaned from the ancient text for the use of ginkgo seeds as a topical treatment for skin disorders. Skin pathogens are of particular interest to the Quave lab, which focuses on finding new approaches to treat antibiotic-resistant bacteria.

Huang gathered ginkgo samples from trees on campus, including seeds and immature whole seeds. She purchased additional fresh seeds from a local farmer’s market for the research and obtained nine chemicals known to be in ginkgo from chemical suppliers in their pure form.

The researchers processed the extractions from the seeds as closely as possible to the recommendations of the Ben Cao Gang Mu, using either water, ethanol, or rape seed oil. Huang and Chassagne conducted microbial experiments—including the evaluation of ginkgo extracts from the seed nut, immature seeds, and the seed coat—on 12 different bacterial strains.

The results showed that the ginkgo seed coats and the immature seeds exhibited antibacterial activity on three of the strains tested: C. acnes, S. aureus, and S. pyogenes. Statistical analysis also found a positive correlation between the antimicrobial activity of the ginkgo samples and the concentration of ginkgolic acid C15:1, suggesting it was involved in the activity.

“Our finding is still in a basic, benchtop phase—these extracts have not yet been tested in animal or human studies—but it is still a thrill for me to learn that this ancient story in the Ben Cao Gang Mu appears to be real,” Huang says. “As a student pharmacist, this gives me more appreciation for the value of using ancient plant remedies to guide modern-day research.”

The research appears in Frontiers in Microbiology.

Source: Emory University

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Sea snake and elephant skin have a trick in common

Thu, 2019-04-18 11:57

Both elephants and yellow-bellied sea snakes have skin that can create a water sheath around the animal, research finds.

In addition, sea snake skin has evolved to permit the animal to thrive as the only pelagic species of venomous sea snake. (Pelagic refers to species residing in the open sea.)

The new study, published in the Journal of Morphology, is the first to quantify the water-retention capacity of sea snake skin, which is crucial to their ability to rest on the surface of the ocean to bask and travel great distances oversea without drying out.

A yellow-bellied sea snake (Hydrophis platurus). (Credit: Mark Sandfoss/U. Florida)

Squamates (snakes and lizards) have a thicker, cornified outer layer of skin called the stratum corneum that allows them to thrive in many arid or semi-arid environments. The stratum corneum includes a lipid- and keratin-based permeability barrier. Yet Hydrophis platurus has an unusual skin structure.

To support H. platurus’ ability to move between the ocean’s surface and depths, the outer keratin level is thinner to allow for improved respiratory gas exchange in the skin. The skin also includes filamentous receptors that permit the snake to detect nearby prey and even help distinguish freshwater from seawater.

“I realized from natural history and photographs of elephants that the superficial structure of the skin had similarities with that of toads, and that both animals used capillary attraction forces to help wet the skin and keep the superficial epidermis from drying,” says Harvey Lillywhite, professor of biology at the University of Florida.

“Elephants wallow when they can find water holes, and the adaptive function of the sculptured surfaces is similar to that of toads that were studied previously.”

The sea snake species’ enormous range takes it across the Indo-Pacific Oceans, and it moves between the surface of the water down to depths of 50 feet. According to Lillywhite, because of this unusual habitat, its skin has some distinct features, including furrows along its scales, as opposed to the overlapping morphology of other snakes’ scales.

These furrows collect water and form a sheath around the snake. A similar structure is evident in elephant skin. Indeed, this research shows that the meso layer of H. platurus’ skin features a “brick and mortar” organization of lipids that is closer to mammalian skin and is markedly different from most squamates’ skin.

Moreover, to keep from drying out while constantly immersed in seawater, sea snake skin actively creates lipids to enhance the permeability barrier. This increased production of lipids to keep the skin hydrated is unusual among squamates, including other species of sea snakes, but has parallels to the skin of cetaceans (dolphins and whales).

Lillywhite’s coauthor, Gopinathan Menon from the California Academy of Sciences, says, “We get an evolutionary insight into what preceded the development of mammalian skin barrier, what pre-adaptations allowed the mammals to go back into an aquatic life as mammals and birds evolved from reptiles.”

Source: University of Florida

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Morphing origami could lead to better concert halls and drones

Thu, 2019-04-18 10:48

A new type of origami can morph from one pattern to another—or even a hybrid of two patterns—instantly altering many of its structural characteristics.

The research could unlock new types of origami-based structures or metamaterials that leverage the characteristics of two types of origami.

Scientists have used origami-based structures to create deployable solar arrays for space, adaptable acoustic systems for symphony halls, and even crash protection systems for flying drones.

“This hybrid origami allows for reprogrammable mechanical properties and the ability to change those properties while the material is in service,” says Glaucio Paulino, a professor in the School of Civil and Environmental Engineering at Georgia Tech.

(Credit: Allison Carter)

The researchers started with two types of origami patterns: the Miura-ori and the eggbox, both of which can form into sheets of repeating patterns. The Miura-ori looks like rows of folded zigzags, while the eggbox pattern resembles a mountain range with repeating peaks and valleys.

Both can compress into a very small space, but when expanded behave differently from one another in how they respond to bending. The eggbox pattern resembles a dome when bent, and the Miura-ori takes the shape of a saddle.

“Traditionally, if you have an eggbox pattern, you are locked into the characteristics of that particular pattern,” Paulino says. “With this new pattern, which we are calling morph, that’s no longer the case.”

A redesign of the geometry of two of the four planes that comprise one section of the origami allows the new pattern to achieve its morphing ability. Shrinking the two planes on one side enables their creases to shift from a mountain to a valley, or in other words, to fold in the opposite direction.

And importantly, the transition from peak to valley can occur whether the origami forms from a flexible material such as paper or a rigid material such as metal.

That means, for example, that origami-based structures used for acoustic systems—which can already expand and contract to increase or decrease the volume of the sound response—could go one step further, changing how they bend to potentially offer an even greater range of resonant responses.

In the example of the drone crash protection system, the new origami pattern could potentially offer other customization options or alter aspects of its impact resistance, Paulino says.

The new origami pattern can also take on a hybrid structure, where certain rows fold into one configuration and others fold in the other. In such a configuration, the structure would exhibit characteristics of both types.

“There are a large number of combinations in terms of how these could be configured, which offers a lot of customization possibilities for structures based on the morph pattern,” says Ke Liu, a postdoctoral scholar at the California Institute of Technology.

Another unique characteristic of the morph pattern happens when a Miura-ori row lies between two eggbox rows. Typically, when tension pulls apart either of the patterns, they give in and flatten their shape. However, in this new instance, the Miura-ori pattern locks into place.

“The locking is very strong, and there is no way to break that hold other than to tear the entire structure apart,” says Phanisri Pratapa, an assistant professor of civil engineering at the Indian Institute of Technology Madras.

The locking could enable structures to limit the amount of expansion possible and change that limit on the fly, Pratapa says.

The research appears in Physical Review Letters. The National Science Foundation and the Raymond Allen Jones Chair at Georgia Tech supported the work.

Source: Georgia Tech

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Quick learners have speedier neurons

Thu, 2019-04-18 10:43

The speed with which a person is able to grasp, process, understand, store, and use information comes down to the speed and timing with which the neurons in the brain fire off, research finds.

The closer the gap between the firing of one neuron and the next, the greater the speed with which they receive the information, store it, and act upon it.

In other words, when it comes to quick thinking, timing makes all the difference. The research  provides fundamental information about the precise timing that can critically affect the formation of memory processes.

Snappy synapses

The capacity to adapt and learn with experience is one of the most intriguing features of the human brain. This fascinating organ is composed of billions of neurons, which are in turn connected to many other cells. The physical connections between neurons, called synapses, are where neurons communicate with each other.

Synapses are remarkably plastic—these connections can strengthen or weaken dynamically in response to incoming information. Such changes in the efficacy of the synapses underlie learning and the formation of memory in the brain.

Researchers at NUS Yong Loo Lin School of Medicine found that neurons in the hippocampus, a brain region critical for the formation of memory, use a surprisingly wide variety of learning mechanisms. One such form of learning, termed “spike-timing-dependent plasticity (STDP),” depends on the timing of each pair of electrical spikes (electrical activity used to transmit information within neurons) in the pre-synaptic neuron and the post-synaptic neuron. An electrical spike in the presynaptic neuron stimulates the neuron to release neurotransmitters, which travel across the synapse to activate the postsynaptic neuron, where it converts information back into an electrical spike.

When the pre- and postsynaptic neurons are active at the same time (less than 30 milliseconds apart), the connections between them strengthen. However, when the presynaptic neuron fires earlier by 30 milliseconds or more, or when the postsynaptic neuron fires earlier by more than 10 milliseconds, the connections strengthen to a lesser degree.

In addition, the researchers demonstrated that when the pre- and postsynaptic spikes occur at the same time, the increase in synaptic strength persists for several hours, and the synapse can even strengthen weak information so that it gets stored. The effect was specific, working only to strengthen this synapse, not to enhance changes in other synapses. This study reveals how important the split-second timing in neuronal activity is in shaping information processing in the brain.

The researchers could detect the longer-term effects of the inter-spike timing because they studied the synaptic changes for a longer duration (4 hours) than previous studies, which were typically less than 1.5 hours.

The STDP model has been proposed to explain spatial and temporal sequence learning. Moreover, the STDP model comes in handy in various situations where object identification and decision-making have to be done quickly, e.g. projectile avoidance or friend-foe identification.

For instance, when a ball is flying towards us, we have to identify the object and its trajectory of travel within a very small window of time, in order to swiftly take action to avoid being hit. Similarly, when we come across another person, we have to quickly decide whether they are a friend or a foe. And this recognition requires the coordinated action of various areas of the brain within an activity timing window explained by STDP.

Timing is everything

“Unfortunately, the ability for the brain to change in response to such precise timing of information flow may be lacking in brains affected by Alzheimer’s disease as the hippocampus is particularly damaged in this common cause of dementia,” says Christopher Chen, senior consultant neurologist at National University Hospital and director of the Memory Aging and Cognition Centre in the National University Health System.

“This study may provide the foundation for understanding how such timing differences alter brain function and also how these changes could be reversed or mitigated. This might enable clinicians to help patients who suffer from memory loss.”

A comprehensive understanding of the factors that shape neural connections is critical for our understanding of information processing in the brain. It also helps us to understand how memories form. Furthermore, a firm grasp of these neural computational rules can help guide the building of artificial intelligence technology, e.g. deep neural networks, which take inspiration from the brain’s learning mechanisms.

“In the case of Autism Spectrum Disorder, some of the neural systems are more active than the others. This could be the reason why some autistic people are good at certain tasks like arts or mathematics, but have difficulty socializing. Using artificial intelligence, it might be possible to identify the neural networks that are more or less active and it might be possible to normalize their functioning using STDP rules,” says Sajikumar Sreedharan of the physiology department of the National University of Singapore.

Based on this improved understanding of how normal brains compute information and learn, researchers can identify mechanisms for further study that may be involved in conditions like schizophrenia, depression, sleep loss, stroke, chronic pain, learning disability, and Alzheimer’s disease.

The study appears in the Proceedings of the National Academy of Sciences.

Source: National University of Singapore

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Same-sex couples 73% more likely to get mortgage denial

Thu, 2019-04-18 10:24

Mortgage lenders are less likely to approve same-sex couples, research finds.

Researchers in Iowa State University’s Ivy College of Business analyzed national mortgage data from 1990 to 2015 and found the approval rate for same-sex couples was 3 to 8 percent lower. The study also includes a smaller dataset with more detail about applicants’ work history and credit worthiness.

Based on this data, same-sex applicants were 73 percent more likely to get a denial than heterosexual couples.

Same-sex couples who were approved paid more in interest and fees. Coauthors Hua Sun and Lei Gao, associate and assistant professors of finance, respectively, say the difference in finance fees averaged less than .5 percent, but combined added up as much as $86 million annually.

The research, published in the Proceedings of the National Academy of Sciences, found no evidence that same-sex couples had a higher default risk.

“Lenders can justify higher fees, if there is greater risk,” Gao says. “We found nothing to indicate that’s the case. In fact, our findings weakly suggest same-sex borrowers may perform better.”

Equal access to credit

While mortgage applicants are not required to disclose their sexual orientation, the researchers say perception is just as damaging in terms of discrimination. The Fair Housing and Equal Credit Opportunity acts prohibit discrimination based on a borrower’s race, gender, marital status, or religion, but neither specifically lists sexual orientation.

The researchers say the findings illustrate a need for change to make the law fair for everyone. Loan decisions should be based on fundamental economic factors, not skin color, sexual orientation, or gender. Sun says making sexual orientation a protected class would limit potential discrimination.

“Policymakers need to guarantee same-sex couples have equal access to credit,” Sun says. “Using our framework, credit monitoring agencies also can take steps to investigate unfair lending practices.”

Neighborhood effects

Sun and Gao used data from the Home Mortgage Disclosure Act, the Federal Reserve Bank of Boston, and Fannie Mae Loan Performance to test whether perceived sexual orientation affected mortgage approval, cost, and performance. Using these datasets allowed researchers to validate their findings and control for factors such as income, variations in lenders’ underwriting standards, and property type, which may influence approval rates.

Co-applicants of the same gender were identified as same-sex couples for the study. The researchers used Gallup and Census Bureau data of geographic distributions of LGBT adults to verify their identification strategy and reported a good matching quality.

Previous research has shown that recent home purchases or refinancing in a neighborhood can predict defaults, which influences mortgage lending approval and interest rates. To determine if the percentage of LGBT individuals living in a neighborhood contributed to the disparity in approval rates, Sun and Gao looked at county-level percentages of same-sex applicants each year.

What they found was somewhat surprising. In neighborhoods with more same-sex couples, both same-sex and different-sex borrowers seem to experience more unfavorable lending outcomes overall. The researchers say the findings should raise enough concern to warrant further investigation.

Source: Iowa State University

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Stress doesn’t stop male lizards from showing off

Thu, 2019-04-18 09:11

The physical traits and behaviors that lizards use to attract potential mates and fend off competitors may be so important that they don’t change in the face of stress.

A new study shows that low levels of stress-associated hormones don’t affect the blue and black badges on the throats and abdomens of male fence lizards—or the signaling behaviors used to show them off.

“Animals in the wild experience stress every day when they flee from predators, fight with others over food, or face extreme weather,” says Kirsty MacLeod, a postdoctoral scholar at Penn State at the time of the research and lead author of the paper, which appears in Scientific Reports.

“But they are facing increasing amounts of stress due to increased interactions with people, a changing climate, and other anthropogenic changes. Because of this, it is rapidly becoming more important to understand the myriad effects of stress on population health.”

Billboard ads

The researchers studied the effects of stress on “secondary sexual traits,” which, like a deer’s antlers or a bird’s brilliant colors, are important in attracting mates or warding off potential rivals, and ultimately contribute to an animal’s ability to reproduce.

Specifically, they studied the blue and black badges that appear on the throats and abdomens of male eastern fence lizards.

“Secondary sexual traits are the billboard ads animals use to advertise their condition,” MacLeod says. “Being more colorful or having bigger ornaments—like antlers—than your neighbor, could mean the difference between mating and passing on your genes, or not mating at all.

“They also help in maintaining a great territory that can provide resources for your offspring and preventing constant attack by rival males. If stress affects these secondary sexual traits, it could affect which individuals are successful in mating or holding territories, which could in turn affect the evolution and persistence of these populations—even though these traits are often not thought of as being central to population health.”

The researchers found that the color of a lizard’s badges is not related to the normal circulating levels of the stress hormone corticosterone in their blood. Additionally, artificially elevating levels of corticosterone, replicating the elevation that occurs when a lizard encounters a stressor like a predator, repeatedly over the course of a few weeks did not affect badge color.

Lizard push-ups

In addition to investigating the physical trait of badge color, the research team also looked at how the trait is displayed through behaviors. Much like a male peacock might raise its colorful tail, fence lizards perform push-ups and bob their heads to show off their badges, warding off other males or attracting potential mates.

“If stress did not affect color but did affect the behavior, for example if lizards stopped doing push-ups, then it wouldn’t matter if their color was the same because it wouldn’t be seen,” MacLeod says. “It would be like having a big flashy billboard lying on the ground.”

Elevating stress hormones did not affect signaling behaviors, including the number of push-ups or head bobs that the lizards performed, the researchers found.

“We know that elevating stress hormones can have important effects in this lizard species, including on immune function and behaviors that allow them to deal with predators, so these results are particularly interesting,” says Tracy Langkilde, professor and head of biology and senior author of the paper.

“It may be that low-level stress is not enough to impact these traits. Or that sexual signaling—to find better mates and maintain better territories—is so important that, when lizards experience stress, more resources are allocated to maintain them.”

Negative results

Next, the researchers plan to investigate whether maintaining these signaling traits under stress has an increased physiological cost on other aspects of lizard health and survival.

Sharing negative results like these, which show that a factor of interest does not have an effect, provide meaningful information and can challenge the status quo, the researchers say.

“It’s always cool to show that something you expected to have an impact on animals, like stress, does so, but it’s equally important to show where there is no impact,” MacLeod says.

“If we only reported results that show stress having an impact, we might over-estimate the effects of stress. Our results suggest that animals are resilient to stress where it matters: in the context of sexual signaling, which is likely to be critical in determining their ability to successfully reproduce.”

Gail McCormick, a graduate student at Penn State at the time of the research and currently a research fellow at Lund University in Sweden, contributed to the research, which received funding from the National Science Foundation and the Society of Ichthyologists and Herpetologists.

Source: Penn State

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A new kind of signal points to neutron star mergers

Thu, 2019-04-18 08:34

NASA’s Chandra X-ray Observatory has discovered a bright burst of X-rays in a galaxy 6.6 billion light years from Earth.

This event likely signaled the merger of two neutron stars—dense stellar objects packed mainly with neutrons—and could give astronomers fresh insight into how neutron stars are built.

When two neutron stars merge they produce jets of high-energy particles and radiation fired in opposite directions. If the jet is pointed along the line of sight to Earth, astronomers can detect a flash, or burst, of gamma rays. If the jet is not pointed in our direction, a different signal is necessary to identify the merger, such as the detection of gravitational waves—ripples in space time.

Now, with the observation of a bright flash of X-rays, astronomers have found a different kind of signal that could indicate a merger, and discovered that two neutron stars likely merged to form a new, heavier, and fast-spinning neutron star with an extraordinarily strong magnetic field.

A bright burst of X-rays that NASA’s Chandra X-ray Observatory discovered likely signals the merger of two neutron stars— dense stellar objects packed mainly with neutrons. The source of the X-rays, dubbed XT2, is located in the Chandra Deep Field South (CDF-S), a small patch of sky in the Fornax constellation. The wider field of view shows an optical image from the Hubble Space Telescope of a portion of the CDF-S field, while the inset shows a Chandra image focusing only on XT2. (Credit: X-ray: NASA/CXC/U. of Science and Technology of China/Y. Xue et. al.; Optical: NASA/STScI)

“We’ve found a completely new way to spot a neutron-star merger,” says Yongquan Xue, professor at the University of Science and Technology of China (USTC) and lead author of the paper; Xue was formerly a postdoctoral researcher at Penn State.

“The behavior of this X-ray source matches what one of our team members predicted for these events.”

XT2 discovery

Chandra observed the source, dubbed XT2, as it suddenly appeared and then faded away after about seven hours. The source is in a region of the sky known as the Chandra Deep Field-South, which is the focus of the deepest X-ray image ever taken, containing almost 12 weeks of Chandra observing time taken at various intervals over nearly 16 and a half years. XT2 appeared on March 22, 2015, and scientists discovered it later in analysis of archival data.

“The serendipitous discovery of XT2 makes another strong case that nature’s fecundity repeatedly transcends human imagination,” says coauthor Niel Brandt, professor of astronomy and astrophysics and professor of physics at Penn State, as well as principal investigator of the relevant Chandra Deep Field-South data.

The researchers identified the likely origin of XT2 by studying how its X-ray light varied with time, and comparing this behavior with predictions made in 2013 by coauthor Bing Zhang, professor and associate dean for research at the University of Nevada, Las Vegas.

The X-rays showed a characteristic signature that matched those astronomers predicted for a newly-formed magnetar—a neutron star spinning around hundreds of times per second and possessing a tremendously strong magnetic field about a quadrillion times that of Earth’s.

The team thinks that the magnetar lost energy in the form of an X-ray-emitting wind, slowing down its rate of spin as the source faded. The amount of X-ray emission stayed roughly constant in X-ray brightness for about 30 minutes, then decreased in brightness by more than a factor of 300 over 6.5 hours before becoming undetectable. This behavior indicates that the neutron star merger produced a new, larger neutron star that survived at least a few hours rather than collapsing immediately into a black hole.\

This result is important because it gives astronomers a chance to learn about the interior of neutron stars, objects that are so dense that their properties could never be replicated on Earth.

“We can’t throw neutron stars together in a lab to see what happens, so we have to wait until the universe does it for us,” says Zhang. “If two neutron stars can collide and a heavy neutron star survives, then this tells us that their structure is relatively stiff and resilient.”

Massive mergers

Neutron-star mergers have been prominent in the news since the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves from one in 2017. That source, known as GW170817, produced a burst of gamma rays and an afterglow in light many other telescopes, including Chandra, detected. The research team thinks that XT2 would also have been a source of gravitational waves, however it occurred before Advanced LIGO started its first observing run, and it was too distant to have been detected in any case.

The team also considered whether a different phenomenon, the collapse of a massive star, could have caused XT2 rather than a neutron star merger. However, XT2 is in the outskirts of its host galaxy, which aligns with the idea that supernova explosions that left behind the neutron stars kicked them out of the center a few billion years earlier.

The galaxy itself also has certain properties—including a low rate of star formation compared to other galaxies of a similar mass—that are much more consistent with the type of galaxy where the merger of two neutron stars is expected to occur. Massive stars, by contrast, are young and associated with high rates of star formation.

“The host-galaxy properties of XT2 indeed boost our confidence in explaining its origin,” says coauthor Ye Li, from Peking University.

The team estimated the rate at which events like XT2 should occur, and found that it agrees with the rate deduced from the detection of GW170817. However, both estimates are highly uncertain because they depend on the detection of just one object each, so more examples are needed.

“There must be more exciting transients that are still undiscovered in Chandra’s archival X-ray data,” says Guang Yang, graduate student in astronomy and astrophysics at Penn State and an author of the paper whose current research focuses on rate constraints for events like XT2. “These old data are really a gold mine.”

Additional researchers from Penn State, Nanjing University, Pontifica Universidad Católica de Chile, University of Arkansas, USTC, and the Chinese Academy of Sciences contributed to the research. Chandra’s Advanced CCD Imaging Spectrometer gathered the relevant data for this research. NASA’s Marshall Space Flight Center in Huntsville, Alabama manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts controls Chandra’s science and flight operations.

Source: Penn State

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What it means when lungs crackle and wheeze

Wed, 2019-04-17 19:15

Crackling and wheezing lungs could be the sounds of a disease progressing, according to new research.

A new study describes how the mechanics that produce those noises with every breath are likely a cause of injury and inflammation.

The findings, based on evidence from experiments on microfluidic chips and on animal models, could eventually change treatment of lung diseases, says James Grotberg, professor of biomedical engineering at the College of Engineering and professor of surgery at the Medical School at the University of Michigan. They also represent a paradigm shift for how doctors understand what they hear through a stethoscope.

Here, Grotberg answers explains his research, which appears in the Annals of the American Thoracic Society.

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Sticky patch reduces damage after heart attack

Wed, 2019-04-17 18:57

An adhesive patch can provide support for damaged heart tissue, report researchers.

The new patch may one day help  reduce the stretching of heart muscle that often occurs after a heart attack.

Researchers developed the patch, which they made from a water-based hydrogel material, using computer simulations of heart function in order to fine tune the material’s mechanical properties. A study with rats showed that the patch was effective in preventing left ventricle remodeling—a stretching of the heart muscle that’s common after a heart attack and can reduce the function of the heart’s main pumping chamber.

The research also showed that the computer-optimized patch outperformed patches whose mechanical properties had been selected on an ad hoc basis.

Support system

“Part of the reason that it’s hard for the heart to recover after a heart attack is that it has to keep pumping,” says Huajian Gao, a professor of engineering at Brown University and a coauthor of the paper. “The idea here is to provide mechanical support for damaged tissue, which hopefully gives it a chance to heal.”

Prior research had shown that mechanical patches could be effective, the researchers say, but no one had done any research on what the optimum mechanical properties of such a patch might be. As a result, the thickness and stiffness of potential patches varies widely. And getting those properties right is important, Gao says.

“If the material is too hard or stiff, then you could confine the movement of the heart so that it can’t expand to the volume it needs to,” he says. “But if the material is too soft, then it won’t provide enough support. So we needed some mechanical principles to guide us.”

To develop those principles, the researchers developed a computer model of a beating heart, which captured the mechanical dynamics of both the heart itself and the patch when fixed to the heart’s exterior. Yue Liu, a graduate student who led the modeling work, says the model had two key components.

“One part was to model normal heart function—the expanding and contracting,” Liu says. “Then we applied our patch on the outside to see how it influenced that function, to make sure that the patch doesn’t confine the heart. The second part was to model how the heart remodels after myocardial infarction, so then we could look at how much mechanical support was needed to prevent that process.”

Fluid and solid qualities

With those properties in hand, the team turned to the biomaterials lab of Lei Yang, a PhD graduate who is now a professor at Soochow University and Hebei University of Technology in China. Yang and his team developed a hydrogel material made from food-sourced starch that could match the properties from the model.

The key to the material is that it’s viscoelastic, meaning it combines fluid and solid properties. It has fluid properties up to a certain amount of stress, at which point it solidifies and becomes stiffer. That makes the material ideal for both accommodating the movement of the heart and for provided necessary support, the researchers say.

The material is also cheap (a patch costs less than a penny, the researchers say) and easy to make, and experiments showed that it was nontoxic. The rodent study ultimately showed that it was effective in reducing post-heart attack damage.

“The patch provided nearly optimal mechanical supports after myocardial infarction (i.e. massive death of cardiomyocytes),” says coauthor Ning Sun, a cardiology researcher at Fudan University in China. “[It] maintained a better cardiac output and thus greatly reduced the overload of those remaining cardiomyocytes and adverse cardiac remodeling.”

Biochemical markers showed that the patch reduced cell death, scar tissue accumulation, and oxidative stress in tissue damaged by heart attack.

More testing is required, the researchers say, but the initial results are promising for eventual use in human clinical trials.

“It remains to be seen if it will work in humans, but it’s very promising,” Gao says. “We don’t see any reason right now that it wouldn’t work.”

The research appears in Nature Biomedical Engineering.

The National Natural Science Foundation of China and the US National Science Foundation supported the research.

Source: Brown University

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Scientists use ‘x-ray vision’ to see how catfish nab prey

Wed, 2019-04-17 13:53

Scientists used a powerful X-ray imaging system to discover how catfish move joints throughout their head in a concerted manner to suck in their prey.

The imaging system, which tracked catfish as they caught and swallowed prey, helped scientists develop a precise understanding of the complex set of motions required to create the suction necessary to eat. They found that many of the bones in the catfish skull work in a coordinated manner to catch food—but move more independently when it’s time to swallow.

“Fish have the most mobile skulls of vertebrates,” says Aaron Olsen, a postdoctoral research associate in Brown University’s ecology and evolutionary biology department. “Fish have over a dozen moving pieces in their skull, and they’re all connected together by joints and ligaments in these closed loops called ‘linkages’ in engineering.

A video of a catfish catching and swallowing an earthworm that shows the coordinated head movements necessary to feed. (Credit: Brainerd Lab/Brown)

“In comparison, humans have moving lower jaws and middle ear bones, but that’s it. The heads of fishes also have very diverse shapes, so we can study how these complex systems evolved in lots of different linages of fishes.”

Bones and muscles

To make the observations, researchers used a 3D-imaging technology called X-ray Reconstruction of Moving Morphology (XROMM). The technology combines CT scans of a skeleton with high-speed X-ray video, aided by tiny implanted metal markers, to create visualizations of how bones and muscles move inside humans and animals.

The technique is so precise that scientists can track movements with errors equivalent to only the width of a human hair.

“XROMM basically gives us X-ray vision to watch how multiple bones move within an animal as they perform a behavior,” Olsen says.

A model of a catfish skull with each bone highlighted in a different color. Catfish have over a dozen moving pieces in their skull. (Credit: Aaron Olsen/Brown)

In this study, the team used XROMM to watch three catfish catch and swallow prey—including food pellets, bits of squid, and earthworms. First, the fish move their whisker-like barbels back and forth in the tank.

Immediately after a barbel touches a piece of food, four primary bones that surround the mouth and throat expand outward in a consistent and coordinated manner to form the suction necessary to catch it.

On the other hand, these bones move more independently and less consistently as the fish swallow. Olsen isn’t certain why swallowing is less coordinated.

The result of the XROMM video of catfish capturing and then swallowing prey, showing the strong coordination the four primary skull bones during prey capture and the more independent movements of the bones during swallowing. (Credit: Brainerd Lab/Brown)

“It seems like different tasks need different levels of coordination,” Olsen said. “But what determines a good level of coordination for a specific task is an open question. What our study shows is that these natural behaviors have different levels of coordination. We’re not sure if they strictly require different levels of coordination.”

Different shapes, same tasks

Previous research from the lab of professor and senior researcher Elizabeth Brainerd used XROMM to study the feeding behavior of other fish, including bass and sharks. Largemouth bass protrude their jaws, which helps catch prey, but catfish can’t protrude their jaws that way, Olsen says. Instead, the bone critical for that action in bass evolved into the base of the whisker-like barbels in catfish.

Bamboo sharks are distantly related to all bony fish, including catfish. However, both bamboo sharks and catfish have powerful shoulders, or pectoral girdles, that both species move extensively during feeding, Olsen says.

Comparing different species of fish with different body shapes, skull structures, and feeding behaviors can clarify how fish with different body shapes evolved different structures and mechanisms to solve similar tasks, Olsen says.

Olsen is in the process of constructing a model to explain how the bones and ligaments that comprise the catfish skull move together as a complex system.

The paper appears in the Proceedings of the Royal Society B. Additional coauthors are from Brown and George Washington University. The National Science Foundation and the Bushnell Research and Education Fund supported the research.

Source: Brown University

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Can an algorithm replace animal testing for chemicals?

Wed, 2019-04-17 13:39

A low-cost, high-speed algorithm may make animal toxicity testing a thing of the past.

Toxicity testing—determining the amount of exposure to a chemical that is unsafe for humans—is vital to the safety of millions of workers in various industries. But researchers have not comprehensively tested a majority of the 85,000 compounds in consumer products for safety.

Animal testing, in addition to its ethical concerns, can be too costly and time consuming to meet this need, according to a new study in Environmental Health Perspectives.

“There is an urgent, worldwide need for an accurate, cost-effective and rapid way to test the toxicity of chemicals, in order to ensure the safety of the people who work with them and of the environments in which they are used,” says lead researcher Daniel Russo, a doctoral candidate at the Rutgers University-Camden Center for Computational and Integrative Biology. “Animal testing alone cannot meet this need.”

Previous efforts to solve this problem used computers to compare untested chemicals with structurally similar compounds whose toxicity is already known. But those methods could not assess structurally unique chemicals—and the fact that some structurally similar chemicals have very different levels of toxicity confounded them.

The researchers overcame these challenges by developing a first-of-its-kind algorithm that automatically extracts data from PubChem, a National Institutes of Health database of information on millions of chemicals. The algorithm compares chemical fragments from tested compounds with those of untested compounds, and uses multiple mathematical methods to evaluate their similarities and differences in order to predict an untested chemical’s toxicity.

“The algorithm developed by Daniel and the Zhu laboratory mines massive amounts of data, and discerns relationships between fragments of compounds from different chemical classes, exponentially faster than a human could,” says coauthor Lauren Aleksunes, an associate professor at Rutgers’ Ernest Mario School of Pharmacy and the Environmental and Occupational Health Sciences Institute.

“This model is efficient and provides companies and regulators with a tool to prioritize chemicals that may need more comprehensive testing in animals before use in commerce.”

To fine-tune the algorithm, the researchers began with 7,385 compounds with known toxicity data, and compared it with data on the same chemicals in PubChem. They then tested the algorithm with 600 new compounds.

For several groups of chemicals, the algorithm had a 62 percent to 100 percent success rate in predicting their level of oral toxicity. And by comparing relationships between sets of chemicals, they shed light on new factors that can determine the toxicity of a chemical.

Although researchers only directed the algorithm to assess the chemicals’ level of toxicity when consumed orally, the researchers conclude that their strategy can extend to predict other types of toxicity.

“While the complete replacement of animal testing is still not feasible, this model takes an important step toward meeting the needs of industry, in which new chemicals are constantly under development, and for environmental and ecological safety,” says coauthor Hao Zhu, an associate professor of chemistry.

Additional researchers from Rutgers, Integrated Laboratory Systems, Johns Hopkins Bloomberg School of Health, and the University of Kostanz contributed to the work.

Source: Rutgers University

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Political divide takes a toll on immigrants’ health

Wed, 2019-04-17 11:30

A new study, drawn from a broader research project on immigrant health highlights the ways partisan rhetoric and cultural divides become stressors that can lead to poor health.

Health is more than the genes we inherit from our parents, the food we eat, or the exercise we sweat through at the gym. So-called “social determinants”—our support networks, our access to health care, housing, and a stable income, even our surroundings—affect our physical and mental health, too.

For immigrants to the United States, the current political climate, and debates over issues such as a border wall, become part of the environment that influences health, argues Jane Lee, an assistant professor of social work at the University of Washington.

“People focus so much on policies, like the border wall or the DREAM Act. But it’s not just whether these policies pass; it’s the overall discourse,” argues Jane Lee, an assistant professor of social work at the University of Washington.

“This is a vulnerable and marginalized population, and that climate creates fear and uncertainty, which have impacts on people’s health.”

Fear and hopelessness

The study, which appears in the Journal of Social Policy, identifies the “sociopolitical context” of immigration and how this contributes to health-related behaviors.

Lee interviewed nearly three dozen Latino immigrants, along with another dozen people who work closely with immigrants in social services and community organizations, in a neighborhood in Queens, New York.

The study sample was nearly two-thirds female, with an average age of 39 and a range of time living in the United States, from seven months to 33 years. Most of the participants were from Mexico, Ecuador, and the Dominican Republic.

“I think everybody comes here with a purpose. But being here, they lose it… and once they’re here, that [purpose] is their last thought.”

Part of a larger, 2017 study of HIV prevention and immigration, this study relied on responses from in-depth interviews with participants, and focused on their understandings of, and concerns and day-to-day encounters with, immigration-related discussions and policies.

Researchers grouped their perceptions into general themes: discrimination toward immigrants; unpredictable circumstances; and lack of information.

Participants reported a pervasive, “overarching anti-immigrant sentiment” in society; according to one respondent, a 32-year-old woman from Mexico, most people think of immigrants as “criminals, drunkards, lazy, unkempt… and everything bad.”

Several cited the 2016 election, and then-candidate Donald Trump, in particular, for stoking hostility toward immigrants and promoting punitive immigration policies. Those policies, in turn, are confusing and unpredictable, study participants said, as the distinction among ideas, plans, and consistent, actionable policies are often unclear to them.

That lack of clarity, combined with experiences of discrimination and animosity from others, led to psycho-emotional impacts such as fear and hopelessness, Lee says, as well as physical impacts such as substance abuse and unprotected sex, and an avoidance of medical care or preventive behaviors.

“I think everybody comes here with a purpose. But being here, they lose it… and once they’re here, that [purpose] is their last thought,” said a 29-year-old woman from Ecuador.

Barriers to integration

Many factors shape a person’s actions, including their beliefs about what might happen if they engage in a particular behavior, such as going to see a doctor, or their perceived ability to engage in that behavior, Lee says.

A prevention-oriented approach to health care is “not the first thing on their mind when they’re a new immigrant.”

Even when immigrants intend to engage in healthy behaviors, they may confront environmental constraints that can prevent them from doing so.

One of the community liaisons interviewed for the study said that a prevention-oriented approach to health care is “not the first thing on their mind when they’re a new immigrant,” while other respondents reported being afraid to go to a doctor due to their immigration status, or reluctance because of money.

The stresses cited in the study ultimately serve as barriers to integrating immigrants into society, the study notes. Lee suggests more policies that focus on integration, and more social and health services that proactively reach out to immigrant communities, could not only improve health outcomes, but also lead to a more cohesive society.

Future studies with larger and more geographically diverse groups could explore how immigrants’ perception of public policies shapes their health outcomes, Lee says. The concepts that emerged from this study could guide such research, perhaps with other marginalized populations, to determine links between sociopolitical contexts and health.

“While policy changes are critical for resource allocation and opportunity creation for immigrants in the United States, we cannot simply wait for changes to happen. Health disparities among immigrants constitute urgent social work and public health issues,” Lee says.

“Research can demonstrate the need for systemic and policy level change, and we can work from different levels to address barriers and improve outcomes, today.”

The National Institute of Mental Health and the Center for Latino Adolescent and Family Health at New York University funded the work.

Source: University of Washington

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Society’s gender expectations alter brain cells

Wed, 2019-04-17 10:40

Society’s expectations about gender roles alter the human brain at the cellular level, according to a new paper.

“We are just starting to understand and study the ways in which gender identity, rather than sex, may cause the brain to differ in males and females,” says Nancy Forger, professor and director of the Neuroscience Institute at Georgia State University.

Though the terms “sex” and “gender” are often used interchangeably by the average person, for neuroscientists, they mean different things, Forger says.

“Sex is based on biological factors such as sex chromosomes and gonads [reproductive organs],” she says, “whereas gender has a social component and involves expectations and behaviors based on an individual’s perceived sex.”

These behaviors and expectations around gender identity can be seen in “epigenetic marks” in the brain, which drive biological functions and features as diverse as memory, development, and disease susceptibility. Forger explains that epigenetic marks help determine which genes are expressed and are sometimes passed on from cell to cell as they divide. One generation can also pass them down to the next, she says.

“While we are accustomed to thinking about differences between the brains of males and females, we are much less used to thinking about the biological implications of gender identity,” she says.

“There is now sufficient evidence to suggest that an epigenetic imprint for gender is a logical conclusion. It would be strange if this were not the case, because all environmental influences of any importance can epigenetically change the brain.”

Forger, with doctoral student Laura Cortes and postdoctoral researcher Carla Daniela Cisternas, reviewed previous studies of epigenetics and sexual differentiation in rodents, along with new studies that have linked gendered experiences among humans and changes in the brain.

In one example involving rats, the authors cite a study by University of Wisconsin researchers who gave female rat pups extra attention designed to simulate the increased licking that mother rats normally perform on their male offspring. That treatment led to detectible changes in the brains of the female rats that received extra stimulation as compared to those who got the normal level of attention for female pups.

Among the studies involving humans, researchers considered the example of Chinese society during the Great Chinese Famine from 1959-1961, when many families preferred to spend their limited resources on boys, leading to higher rates of disability and illiteracy among female survivors in adulthood. This demonstrates, they say, that early life stress can be a gendered experience as it changes the neural epigenome.

“Given our lifetimes of layered gendered experiences, and their inevitable, iterative interactions with sex, it may never be possible to completely disentangle the effects of sex and gender on the human brain,” Forger says.

“We can start, however, by including gender in our thinking any time a difference between the brain functioning of men and women is reported.”

The paper appears in Frontiers in Neuroscience. A National Science Foundation Graduate Research Fellowship and a Georgia State Brains & Behavior Seed grant supported the research.

Source: Georgia State University

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What can we learn from the Notre Dame fire?

Wed, 2019-04-17 09:27

A horrific fire claimed most of the roof and iconic spire at the Cathedral of Notre Dame in Paris on April 15, a destructive event that caused potentially even more harm to the 12th century building’s historic and religious artifacts and treasures.

Charles McClendon, a professor of the history of art at Brandeis University, studies art and architecture in western Europe with a particular emphasis on ancient and medieval times.

Here, with the world vowing to rebuild the cathedral, McClendon discusses the Notre Dame’s past and future.

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Opioid epidemic may have cost U.S. $37B in tax revenue

Wed, 2019-04-17 08:52

The opioid epidemic may have cost state and federal governments in the United States up to $37.8 billion in lost tax revenue due to opioid-related employment loss, according to a new study.

Additionally, the researchers found that Pennsylvania was one of the states with the most lost revenue, with approximately $638.2 million lost to income and sales tax. The study looked at data between 2000 and 2016.

The results, which appear in the journal Medical Care, could help governments hoping to make up for lost revenue, says Joel Segel, assistant professor of health policy and administration at Penn State.

“This is a cost that was maybe not thought about as explicitly before, and a cost that governments could potentially try to recoup,” Segel says.

“Instead of focusing on the cost of treating people with opioid use disorder, you could think about it in terms of a potential benefit to getting people healthy, back on their feet, and back in the workforce.”

Previous research estimated that in 2016, nearly 2.1 million Americans had an opioid use disorder, and approximately 64,000 deaths resulted from an opioid overdose. According to the National Institute on Drug Abuse, Pennsylvania alone saw 2,235 opioid-related overdose deaths.

While previous studies have looked at the cost of the opioid epidemic in terms of substance abuse treatment and other medical costs, Segal and the other researchers wanted to explore other costs that previous studies had not captured.

“We wanted to take a systematic approach to how we could think about some of the tax revenue that is lost if someone is unable to work due to opioid use,” Segel says. “This could be an important consideration for either state or federal budgets.”

The researchers used National Survey on Drug Use and Health data, as well as information from a previous study that estimated declines in the labor force due to the opioid epidemic. They used the National Bureau of Economic Research’s TAXSIM calculator to estimate losses in tax revenue.

An analysis of data from 2000 to 2016, showed an estimated decline of 1.6 million participants in the labor force, with about 68,000 of those in Pennsylvania and about 180,000 overdose deaths, with approximately 6,100 occurring in Pennsylvania.

Additionally, the researchers estimated losses of $11.8 billion to state governments and $26 billion to the federal government in tax revenue due to reductions in the labor force. For state governments, this included lost sales tax and income tax revenue. Lost income tax revenue accounted for all the losses to the federal government.

The results help show the value of treating people with opioid use disorder, and should play into treatment program considerations and evaluations, Segel says.

“The state of Pennsylvania has been developing some innovative programs, and our results are something to consider as these programs are being considered for implementation,” Segel says.

“Not only are treatment programs beneficial to the individual and to society, but if you’re thinking about the total cost of these treatment programs, future earnings from tax revenue could help offset a piece of that.”

The Commonwealth of Pennsylvania supported the study.

Source: Penn State

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1 gene connects stem cells in the brain and the gut

Wed, 2019-04-17 08:25

Researchers have identified a new factor that is essential for maintaining the stem cells in the brain and gut.

The loss of this factor may contribute to anxiety and cognitive disorders and to gastrointestinal diseases.

The organs in our bodies house stem cells that are necessary to regenerate cells when they become damaged, diseased, or too old to function.

The study, which appears in the journal Stem Cell Reports, reveals the importance of the insulin-like growth factor II gene in adult stem cell maintenance in both the brain and gut. The gene provides key support for the existence of two, functionally distinct sets of stem cells in the intestine, whose unregulated self-renewal and proliferation may contribute to colorectal cancers.

“The discovery that there is a factor—this gene product—that is common between more than one adult stem cell population is remarkable.”

“The role that the insulin-like growth factor II gene plays in adult stem cells has been largely unknown. This growth factor was previously regarded as dispensable in adults,” says coauthor Steven Levison, director of the Laboratory for Regenerative Neurobiology at Rutgers University New Jersey Medical School.

“The discovery that there is a factor—this gene product—that is common between more than one adult stem cell population is remarkable.”

The findings indicate that this growth factor is essential for multiple types of adult stem cells, including those critical for cognitive function, sense of smell, and for renewing the lining of the small intestine in adults.

In the study, the researchers removed the gene from adult mice either rapidly over 5 days or more slowly over 15 days. In the intestine, the fast deletion of the gene led to a rapid loss of fast-cycling stem cells that replenish the gut lining, leading to dramatic weight loss and death within a week. A slower deletion of the gene allowed the mice to survive due to the recruitment of a second, and more inactive, population of gut stem cells, whose existence researchers had debated.

Additionally, the study revealed that half of the stem cells in two regions of the brain that house neural stem cells were lost, causing deficits in learning and memory, increased anxiety, and a loss of the sense of smell.

“When the gene was removed acutely, the stem cells in glands in the inner surface of the small intestine could not continue their normal cycle of continued cell replacement, causing organ failure,” says coauthor Teresa Wood, a professor at Rutgers New Jersey Medical School.

“However, when the gene was deleted slowly, it gave the other stem cells an opportunity to take over for the lost stem cells.”

Source: Rutgers University

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