Category: Science News

{In a new study, a group of Boston scientists, including researchers at Dana-Farber Cancer Institute, offer a genetic explanation for the age-old conundrum of why cancer is more common in males than females.}

Females, it turns out, carry an extra copy of certain protective genes in their cells — an additional line of defense against the cells growing out of control — the investigators report in a paper published online by Nature Genetics. Though not solely responsible for cancer’s “bias” toward males, the duplicate copies likely account for some of the imbalance, including up to 80 percent of the excess male cases in some tumor types, report the study authors, based at Dana-Farber, the Broad Institute of Harvard and MIT, and Massachusetts General Hospital.

“Across virtually every type of cancer, occurrence rates are higher in males than in females. In some cases, the difference might be very small — just a few percent — but in certain cancers, incidence is two or three times higher in males,” said Andrew Lane, MD, PhD, of Dana-Farber, the co-senior author of the study with Gad Getz, PhD, of the Broad Institute and Massachusetts General Hospital. “Data from the National Cancer Institute show that males carry about a 20 percent higher risk than females of developing cancer. That translates into 150,000 additional new cases of cancer in men every year.”

Despite the size of the gap, the reasons for this divergence have been difficult to discern. The historic explanation — that men were more likely to smoke cigarettes and be exposed to hazardous chemicals in the work environment — has proven inadequate, because even as smoking rates have dropped and occupational patterns changed, men still outpace women in developing many cancers, including some associated with tobacco use such as kidney, renal, bladder, and oral cancers, Lane said. The disparity is present among boys and girls, as well as men and women.

Previous research found that in one form of leukemia, the cancer cells often carried a mutation in a gene called KDM6A, located on the X chromosome — one of the sex chromosomes that determine whether an individual is male or female. (Females cells carry two X chromosomes; males carry an X chromosome and a shorter, smaller Y chromosome.) If KDM6A is a tumor-suppressor gene — responsible for preventing cell division from spinning out of control — the mutation could lead to cancer by crippling that restraint system.

One might expect female cells to be just as vulnerable to the mutation. During embryo formation, one of the X chromosomes in female cells shuts down and remains off-line for life. A mutation in KDM6A on the active X chromosome, therefore, should lead to the same cell-division havoc as it does in males. Unexpectedly, KDM6A mutations were detected more often in male cancers. It turns out that some genes on the inactivated X chromosome in female cells “escape” that dormant state and function normally. One of those awakened genes happens to be a working copy of KDM6A. The “good” copy of the gene is sufficient to prevent the cell from turning cancerous.

The new study explored whether this phenomenon — fully functional tumor-suppressor genes on an otherwise idle X chromosome — underlies the broader phenomenon of cancer’s partiality toward male cells. The researchers dubbed such genes “EXITS,” for Escape from X-Inactivation Tumor Suppressors.

“Under this theory, one of the reasons cancer is more common in males is that male cells would need a harmful mutation in only one copy of an EXITS gene to turn cancerous,” Lane said. “Female cells, by contrast, would need mutations in both copies.”

To test this hypothesis, researchers at the Broad Institute scanned the genomes of more than 4,000 tumor samples, representing 21 different types of cancer, looking for various types of abnormalities, including mutations. They then examined whether any of the irregularities they found were more common in male cells or female cells.

The results were striking. Of nearly 800 genes found solely on the X chromosome, six were more frequently mutated — and incapacitated — in males than females. Of more than 18,000 other genes, none showed a gender imbalance in mutation rates.

Of the six genes more likely to be mutated in males, five were known to escape X chromosome inactivation, making them strong candidates to be EXITS genes.

“The fact that the very genes which are more often mutated in males are found exclusively on the X chromosome — and that several of them are known to be tumor-suppressors and escape X-inactivation — is compelling evidence of our theory,” Lane remarked. “The protection afforded by the working copies of these genes in female cells may help explain the lower incidence of many cancers in women and girls.”

One of the implications of the finding is that many cancers may arise through different molecular pathways in men and women. To circumvent the added genetic safeguards against cancer in female cells, tumors in women may employ alternate genetic circuits than in men.

To explore this possibility, the study authors recommend that future clinical studies of cancer treatments be “statistically powered” ¬- that is, involve enough patients and tumor tissue samples — to understand whether men and women respond differently to treatment because of genetic differences in their tumors.

{An international team of scientists led by the University of Michigan has discovered a new type of photoreceptor — only the third to be found in animals — that is about 50 times more efficient at capturing light than the rhodopsin in the human eye.}

The new receptor protein, LITE-1, was found among a family of taste receptors in invertebrates, and has unusual characteristics that suggest potential future applications ranging from sunscreen to scientific research tools, the team noted in findings scheduled to be published Nov. 17 in the journal Cell.

“Our experiments also raise the intriguing possibility that it might be possible to genetically engineer other new types of photoreceptors,” said senior study author Shawn Xu, a faculty member of the U-M Life Sciences Institute, where his lab is located.

The LITE-1 receptor was discovered in the eyeless, millimeter-long roundworms known as nematodes, a common model organism in bioscience research.

“LITE-1 actually comes from a family of taste receptor proteins first discovered in insects,” said Xu, who is also a professor in the Department of Molecular and Integrative Physiology at the U-M Medical School. “These, however, are not the same taste receptors as in mammals.”

Xu’s lab previously demonstrated that although they lack eyes, the worms will move away from flashes of light. The new research goes a step further, showing that LITE-1 directly absorbs light, rather than being an intermediary that senses chemicals produced by reactions involving light.

“Photoreceptors convert light into a signal that the body can use,” Xu said. “LITE-1 is unusual in that it is extremely efficient at absorbing both UV-A and UV-B light — 10 to 100 times greater than the two other types found in the animal kingdom: opsins and cryptochromes. The next step is to better understand why it has these amazing properties.”

The genetic code of these receptor proteins is also very different from other types of photoreceptors found in plants, animals and microbes, Xu said.

Characterizing the current research as an “entry point,” the researchers said the discovery might prove useful in a variety of ways.

With further study, for example, it might be possible to develop LITE-1 into a sunscreen additive that absorbs harmful rays, or to further scientific research by fostering light sensitivity in new types of cells, the scientists wrote in the paper.

Several characteristics make LITE-1 unusual, Xu said.

Animal photoreceptors typically have two components: a base protein and a light-absorbing chromophore (a role played by retinal, or vitamin A, in human sight). When you break these photoreceptors apart, the chromophore still retains some of its functionality.

This is not the case for LITE-1. Breaking it apart, or “denaturing” it, completely stops its ability to absorb light, rather than just diminishing it — showing that it really is a different model, Xu said.

The researchers also determined that within the protein, having the amino acid tryptophan in two places was critical to its function.

When a nonlight-sensitive protein in the same family, GUR-3, was modified to add the corresponding tryptophan residues, it reacted strongly to ultraviolet light — with about a third the sensitivity to UV-B as LITE-1.

“This suggests scientists may be able to use similar techniques to genetically engineer other new photoreceptors,” Xu said.

{Older bodies need longer to mend. This reality of aging has been documented since World War I, with the observation that wounds heal slower in older soldiers. Yet until now, researchers have not been able to tease out what age-related changes hinder the body’s ability to repair itself.}

Recent experiments at The Rockefeller University explored this physiological puzzle by examining molecular changes in aging mouse skin. The results, described November 17 in Cell, delineate a new aspect of how the body heals wounds.

“Within days of an injury, skin cells migrate in and close the wound, a process that requires coordination with nearby immune cells. Our experiments have shown that, with aging, disruptions to communication between skin cells and their immune cells slow down this step,” says Elaine Fuchs, the Rebecca C. Lancefield Professor and head of the Robin Chemers Neustein Laboratory of Mammalian Cell Biology.

“This discovery suggests new approaches to developing treatments that could speed healing among older people,” adds Fuchs, who is also a Howard Hughes Medical Institute investigator.

{{Return of the skin cells}}

Whenever a wound occurs, the body needs to repair it quickly to restore its protective skin barrier. “Wound healing is one of the most complex processes to occur in the human body,” says Brice Keyes, a former postdoc in Fuch’s lab and currently a researcher at Calico Life Sciences. “Numerous types of cells, molecular pathways, and signaling systems go to work over timescales that vary from seconds to months. Changes related to aging have been observed in every step of this process.” Keyes and Siqi Liu, an immunology specialist and a current Jane Coffin Childs postdoctoral fellow in in the lab, are co-first authors of the Cell article.

Both skin cells and immune cells contribute to this elaborate process, which begins with the formation of a scab. New skin cells known as keratinocytes later travel in as a sheet to fill in the wound under the scab.

The team focused on this latter step in healing in two-month-old versus 24-month-old mice — roughly equivalent to 20- and 70-year-old humans. They found that among the older mice, keratinocytes were much slower to migrate into the skin gap under the scab, and, as a result, wounds often took days longer to close.

Wound healing is known to require specialized immune cells that reside in the skin. The researchers’ new experiments showed that following an injury, the keratinocytes at the wound edge talk to these immune cells by producing proteins known as Skints that appear to tell the immune cells to stay around and assist in filling the gap. In older mice, the keratinocytes failed to produce these immune signals.

{{Seeking a reversal}}

To see if they could enhance Skint signaling in older skin, the researchers turned to a protein that resident immune cells normally release after injury. When they applied this protein to young and old mouse skin tissue in a petri dish, they saw an increase in keratinocyte migration, which was most pronounced in the older skin. In effect, the old keratinocytes behaved more youthfully.

The scientists hope the same principle could be applied to developing treatments for age-related delays in healing.

“Our work suggests it may be possible to develop drugs to activate pathways that help aging skin cells to communicate better with their immune cell neighbors, and so boost the signals that normally decline with age,” Fuchs says.

{Finally, psychologists have discovered a type of face that men are better at identifying than women: the faces on Transformer toys.}

It’s a first. All previous scientific studies have found that either women are better than men at identifying faces or there is no gender difference.

“One of the suggestions of this prior work is that that women are inherently better than men at recognizing faces,” said Isabel Gauthier, David K. Wilson Professor of Psychology at Vanderbilt University, who conducted the new study with graduate student Kaitlin Ryan. “But we believe that experience plays a major role in facial recognition so we tried to come up with some way to test our hypothesis regarding this gender difference.”

The approach they hit upon was testing people’s ability to identify the faces of the toys they played with as children. The researchers’ intuition was that men may have played more with Transformers then Barbies when they were younger, and vice versa for women, and they confirmed this by surveying people about their experience playing with these toys.

“So women had much more experience studying Barbie faces and men had much more experience studying Transformer faces. That difference in experience was just what we needed,” said Gauthier.

To take advantage of this difference, the researchers designed a study that compared men’s and women’s ability to recognize male faces, female faces, Barbie doll faces, Transformer faces and, as a control category, different kinds of cars. The results are described in the article “Gender Differences in Recognition of Toy Faces Suggest a Contribution of Experience” published online by the journal Vision Research on Nov. 3.

The test consisted of giving participants a group of six images to study, and then presenting them with a series of trials that showed them three images — one from the initial set and two that they hadn’t seen before — and asking them to identify the familiar image. They did this with male faces, female faces, Barbie doll faces, Transformer faces and different automobiles.

(There is a popular misconception that all Barbie dolls have the same face. “Different models have distinctly different faces,” said Gauthier. “They appear to be modeled on different women.”)

The researchers administered the test to 295 people: 161 men and 134 women. Some took the test in a laboratory and some took it online through the Amazon Mechanical Turk crowd-sourcing website that psychologists have begun using to conduct large studies. One advantage of the online platform is that the researchers can sample a more diverse population in terms of age, ethnicity and socio-economic status, relative to laboratory studies that generally test undergraduate students.

Replicating prior work, men slightly outperformed women when recognizing cars and, in this study, men and women performed equally well with human faces. “We also found that women had a small but statistically significant advantage at identifying Barbie faces while men had a small but statistically significant advantage in identifying Transformer faces,” said Gauthier. “This is the first category of faces where men do better than women.”

The psychologists considered the possibility that the male advantage was because the participants treated the Transformers as objects rather than faces. Previous studies have shown that men are sometimes better than women recognizing vehicles like cars, planes or motorcycles. That is why the researchers included the automobile recognition task.

The researchers addressed this question by looking at individual differences. They found that those people who were best at recognizing human faces were generally those who were best at recognizing Transformer faces and Barbie faces. In contrast, there was a weaker relation between performance with toy faces and cars, leading them to conclude that the participants were reacting to the toy faces as faces, not as objects. Gauthier’s other research has shown that just a few hours of experience with a new type of face, such as a new alien race from a Star Trek episode, can change how the brain processes these faces. The new research suggests that the experience is long lasting.

“Clearly, the faces you experience as a child leave a trace in your adult memory,” Gauthier said. “It is unlikely that this effect is limited to these particular toys.”

{Acoustical vibrations of heart and vocal cords measured.}

Researchers from the University of Colorado Boulder and Northwestern University have developed a tiny, soft and wearable acoustic sensor that measures vibrations in the human body, allowing them to monitor human heart health and recognize spoken words.

The stretchable device captures physiological sound signals from the body, has physical properties well-matched with human skin and can be mounted on nearly any surface of the body, said CU Boulder Assistant Professor Jae-Woong Jeong, one of three lead study authors. The sensor, which resembles a small Band-Aid, weighs less than one-hundredth of an ounce and can gather continuous physiological data.

“This device has a very low mass density and can be used for cardiovascular monitoring, speech recognition and human-machine interfaces in daily life,” said Jeong of the Department of Electrical, Computer and Energy Engineering. “It is very comfortable and convenient — you can think of it as a tiny, wearable stethoscope.”

A paper on the subject was published Nov. 16 in Science Advances, a sister journal of Science. The other two co-corresponding authors are Professors Yonggang Huang and John Rogers of Northwestern.

“The thin, soft, skin-like characteristics of these advanced wearable devices provide unique capabilities for ‘listening in’ to the intrinsic sounds of vital organs of the body, including the lungs and heart, with important consequences in continuous monitoring of physiological health,” said Rogers, the Simpson Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery. Rogers also is director of Northwestern’s Center for Bio-Integrated Electronics.

The researchers say the new device can pick up mechanical waves that propagate through tissues and fluids in the human body due to natural physiological activity, revealing characteristic acoustical signatures of individual events. They include the opening and closing of heart valves, vibrations of the vocal cords and even movements in gastrointestinal tracts.

The sensor can also integrate electrodes that can record electrocardiogram (ECG) signals that measure the electrical activity of the heart as well electromyogram (EMG) signals that measure the electrical activity of muscles at rest and during contraction.

While the sensor was wired to an external data acquisition system for the tests, it can easily be converted into a wireless device, said Jeong. Such sensors could be of use in remote, noisy places — including battlefields — producing quiet, high-quality cardiology or speech signals that can be read in real time at distant medical facilities.

“Using the data from these sensors, a doctor at a hospital far away from a patient would be able to make a fast, accurate diagnosis,” said Jeong.

Vocal cord vibration signals also could be used by the military personnel or civilians to control robots, vehicles or drones. The speech recognition capabilities of the sensor also have implications for improving communication for people suffering from speech impairments, he said.

As part of the study, the team used the device to measure cardiac acoustic responses and ECG activity -including the detection of heart murmurs — in a group of elderly volunteers at Camp Lowell Cardiology, a private medical clinic in Tucson, Arizona collaborating with the University of Arizona, a project partner. The researchers also were able to detect the acoustical signals of blood clots in a related lab experiment, said Jeong.

Other CU Boulder study co-authors on the Science Advances paper include Assistant Professor Jianliang Xiao and doctoral student Zhanan Zou of mechanical engineering and doctoral student Raza Qazi of electrical engineering.

The sticky, flexible polymer encapsulating the tiny device is stretchable enough to follow skin deformation, said study first author Yuhao Liu, who earned his doctorate and the University of Illinois-Urbana Champaign and now works at Lam Research, headquartered in Fremont, California. The device contains a tiny commercial accelerometer to measure the vibration of the body acoustics and allows for the evaporation of human sweat.

The researchers also showed vocal cord vibrations gathered when the device is on one’s throat can be used to control video games and other machines. As part of the study a test subject was able to control a Pac-Man game using vocal cord vibrations for the words “up,” “down,” “left” and “right.”

“While other skin electronics devices have been developed by researchers, what has not been demonstrated before is the mechanical-acoustic coupling of our device to the body through the skin,” Jeong said. “Our goal is to make this device practical enough to use in our daily lives.”

{Scientists from the National Institutes of Health have identified an antibody from an HIV-infected person that potently neutralized 98 percent of HIV isolates tested, including 16 of 20 strains resistant to other antibodies of the same class. The remarkable breadth and potency of this antibody, named N6, make it an attractive candidate for further development to potentially treat or prevent HIV infection, say the researchers.}

The scientists, led by Mark Connors, M.D., of NIH’s National Institute of Allergy and Infectious Diseases (NIAID), also tracked the evolution of N6 over time to understand how it developed the ability to potently neutralize nearly all HIV strains. This information will help inform the design of vaccines to elicit such broadly neutralizing antibodies.

Identifying broadly neutralizing antibodies against HIV has been difficult because the virus rapidly changes its surface proteins to evade recognition by the immune system. In 2010, scientists at NIAID’s Vaccine Research Center (VRC) discovered an antibody called VRC01 that can stop up to 90 percent of HIV strains from infecting human cells. Like VRC01, N6 blocks infection by binding to a part of the HIV envelope called the CD4 binding site, preventing the virus from attaching itself to immune cells.

Findings from the current study showed that N6 evolved a unique mode of binding that depends less on a variable area of the HIV envelope known as the V5 region and focuses more on conserved regions, which change relatively little among HIV strains. This allows N6 to tolerate changes in the HIV envelope, including the attachment of sugars in the V5 region, a major mechanism by which HIV develops resistance to other VRC01-class antibodies.

The new findings suggest that N6 could pose advantages over VRC01, which currently is being assessed as intravenous infusions in clinical trials to see if it can safely prevent HIV infection in humans. Due to its potency, N6 may offer stronger and more durable prevention and treatment benefits, and researchers may be able to administer it subcutaneously (into the fat under the skin) rather than intravenously. In addition, its ability to neutralize nearly all HIV strains would be advantageous for both prevention and treatment strategies.

{In 2009, applied physicist Peter Sturrock was visiting the National Solar Observatory in Tucson, Arizona, when the deputy director of the observatory told him he should read a controversial article about radioactive decay. Although the subject was outside Sturrock’s field, it inspired a thought so intriguing that the next day he phoned the author of the study, Purdue University physicist Ephraim Fischbach, to suggest a collaboration.}

{{Fischbach replied, “We were about to phone you.”}}

More than seven years later, that collaboration could result in an inexpensive tabletop device to detect elusive neutrinos more efficiently and inexpensively than is currently possible, and could simplify scientists’ ability to study the inner workings of the sun. The work was published in the Nov. 7 issue of Solar Physics.

“If we’re correct, it means that neutrinos are far easier to detect than people have thought,” said Sturrock, professor emeritus of applied physics. “Everyone thought that it would be necessary to have huge experiments, with thousands of tons of water or other material, that may involve huge consortia and huge expense, and you might get a few thousand counts a year. But we may get similar or even better data from an experiment involving only micrograms of radioactive material.”

{{Why, how we study neutrinos}}

For twenty years, Sturrock and his colleague Jeff Scargle, astrophysicist and data scientist at NASA Ames Research Center, have studied neutrinos, subatomic particles with no electric charge and nearly zero mass, which can be used to learn about the inside of the sun.

Nuclear reactions in the sun’s core produce neutrinos. A unique feature of neutrinos is that they rarely interact with other particles and so can escape the sun easily, bringing us information about the deep solar interior. Studying neutrinos is thought to be the best way to obtain direct information about the center of the sun, which is otherwise largely a mystery. Neutrinos can also give us information about supernovas, the creation of the universe and much more.

On Earth, an area the size of a fingernail has 65 billion neutrinos pass through it each second. But only one or two in an entire lifetime will actually stop in our bodies. Studying neutrinos involves massive equipment and expenses to trap enough of the elusive particles for investigation.

At present, the gold standard for neutrino detection is Japan’s Super-Kamiokande, a magnificent $100 million observatory. In use since 1996, Super-Kamiokande lies 1,000 meters below ground. It consists of a tank filled with 50,000 tons of ultra-pure water, surrounded by about 13,000 photo-multiplier tubes. If a neutrino enters the water and interacts with electrons or nuclei there, it results in a charged particle that moves faster than the speed of light in water. This leads to an optical shock wave, a cone of light called Cherenkov radiation. This light is projected onto the wall of the tank and recorded by the photomultiplier tubes.

{{Past challenges in detection}}

The 2002 Nobel Prize in Physics was awarded to Masatoshi Koshiba of Super-Kamiokande and Raymond Davis Jr. of Homestake Neutrino Observatory for the development of neutrino detectors and “for the detection of cosmic neutrinos.” One perplexing detail of this work was that, with their ground-breaking detection methods, they were detecting one-third to one-half as many neutrinos as expected, an issue known as the “solar neutrino problem.” This shortfall was first thought to be due to experimental problems. But, once it was confirmed by Super-Kamiokande, the deficit was accepted as real.

The year prior to the Nobel, however, scientists announced a solution to the solar neutrino problem. It turned out that neutrinos oscillate among three forms (electron, muon and tau) and detectors were primarily sensitive to only electron neutrinos. For the discovery of these oscillations, the 2015 Nobel Prize in Physics was awarded to Takaaki Kajita of Super-Kamiokande and Arthur B. MacDonald of the Sudbury Neutrino Observatory.

Even with these Nobel Prize-worthy developments in research and equipment at their disposal, scientists can still detect only a few thousand neutrino events each year.

{{A new option for research}}

The research that Sturrock learned about in Tucson concerned fluctuations in the rate of decay of radioactive elements. The fluctuations were highly controversial at the time because it had been thought that the decay rate of any radioactive element was constant. Sturrock decided to study these experimental results using analytical techniques that he and Scargle had developed to study neutrinos.

In examining the radioactive decay fluctuations, the team found evidence that those fluctuations matched patterns they had found in Super-Kamiokande neutrino data, each indicating a one-month oscillation attributable to solar rotation. The likely conclusion is that neutrinos from the sun are directly affecting beta-decays. This connection has been theorized by other researchers dating back 25 years, but the Sturrock-Fischbach-Scargle analysis adds the strongest evidence yet. If this relationship holds, a revolution in neutrino research could be underway.

“It means there’s another way to study neutrinos that is much simpler and much less expensive than current methods,” Sturrock said. “Some data, some information, you won’t get from beta-decays, but only from experiments like Super-Kamiokande. However, the study of beta-decay variability indicates there is another way to detect neutrinos, one that gives you a different view of neutrinos and of the sun.”

Sturrock said this could mark the beginning of a new field in neutrino research and solar physics. He and Fischbach see the possibility of bench-top detectors that would cost thousands rather than millions of dollars.

The next steps for now will be to gather more and better data and to work toward a theory that can explain how all these physical processes are connected.

{Traumatic stress affects the brains of adolescent boys and girls differently, according to a new brain-scanning study from the Stanford University School of Medicine.}

Among youth with post-traumatic stress disorder, the study found structural differences between the sexes in one part of the insula, a brain region that detects cues from the body and processes emotions and empathy. The insula helps to integrate one’s feelings, actions and several other brain functions.

The findings will be published online Nov. 11 in Depression and Anxiety. The study is the first to show differences between male and female PTSD patients in a part of the insula involved in emotion and empathy.

“The insula appears to play a key role in the development of PTSD,” said the study’s senior author, Victor Carrion, MD, professor of psychiatry and behavioral sciences at Stanford. “The difference we saw between the brains of boys and girls who have experienced psychological trauma is important because it may help explain differences in trauma symptoms between sexes.”

Smaller insula in traumatized girls

Among young people who are exposed to traumatic stress, some develop PTSD while others do not. People with PTSD may experience flashbacks of traumatic events; may avoid places, people and things that remind them of the trauma; and may suffer a variety of other problems, including social withdrawal and difficulty sleeping or concentrating. Prior research has shown that girls who experienced trauma are more likely to develop PTSD than boys who experience trauma, but scientists have been unable to determine why.

The research team conducted MRI scans of the brains of 59 study participants ages 9-17. Thirty of them — 14 girls and 16 boys — had trauma symptoms, and 29 others — the control group of 15 girls and 14 boys — did not. The traumatized and nontraumatized participants had similar ages and IQs. Of the traumatized participants, five had experienced one episode of trauma, while the remaining 25 had experienced two or more episodes or had been exposed to chronic trauma.

The researchers saw no differences in brain structure between boys and girls in the control group. However, among the traumatized boys and girls, they saw differences in a portion of the insula called the anterior circular sulcus. This brain region had larger volume and surface area in traumatized boys than in boys in the control group. In addition, the region’s volume and surface area were smaller in girls with trauma than among girls in the control group.

Findings could help clinicians

“It is important that people who work with traumatized youth consider the sex differences,” said Megan Klabunde, PhD, the study’s lead author and an instructor of psychiatry and behavioral sciences. “Our findings suggest it is possible that boys and girls could exhibit different trauma symptoms and that they might benefit from different approaches to treatment.”

The insula normally changes during childhood and adolescence, with smaller insula volume typically seen as children and teenagers grow older. Thus, the findings imply that traumatic stress could contribute to accelerated cortical aging of the insula in girls who develop PTSD, Klabunde said.

“There are some studies suggesting that high levels of stress could contribute to early puberty in girls,” she said.

The researchers also noted that their work may help scientists understand how experiencing trauma could play into differences between the sexes in regulating emotions. “By better understanding sex differences in a region of the brain involved in emotion processing, clinicians and scientists may be able to develop sex-specific trauma and emotion dysregulation treatments,” the authors write in the study.

To better understand the findings, the researchers say what’s needed next are longitudinal studies following traumatized young people of both sexes over time. They also say studies that further explore how PTSD might manifest itself differently in boys and girls, as well as tests of whether sex-specific treatments are beneficial, are needed.

The work is an example of Stanford Medicine’s focus on precision health, the goal of which is to anticipate and prevent disease in the healthy and precisely diagnose and treat disease in the ill.

{Humans have always been frightened and fascinated by lightning. This month, NASA is scheduled to launch a new satellite that will provide the first nonstop, high-tech eye on lightning over the North American section of the planet.}

University of Washington researchers have been tracking global lightning from the ground for more than a decade. Lightning is not only about public safety — lightning strike data have recently been introduced into weather prediction, and a new UW study shows ways to apply them in storm forecasts.

“When you see lots of lightning you know where the convection, or heat-driven upward motion, is the strongest, and that’s where the storm is the most intense,” said co-author Robert Holzworth, a UW professor of Earth and space sciences. “Almost all lightning occurs in clouds that have ice, and where there’s a strong updraft.”

The recent paper, published in the American Meteorological Society’s Journal of Atmospheric and Oceanic Technology, presents a new way to transform lightning strikes into weather-relevant information. The U.S. National Weather Service has begun to use lightning in its most sophisticated forecasts. This method, however, is more general and could be used in a wide variety of forecasting systems, anywhere in the world. The authors tested their method on two cases: the summer 2012 derecho thunderstorm system that swept across the U.S., and a 2013 tornado that killed several people in the Midwest. “Using lightning data to modify the air moisture was enough to dramatically improve the short-term forecast for a strong rain, wind and storm event,” said first author Ken Dixon, a former UW graduate student who now works for The Weather Company. His simple method might also improve medium-range forecasts, for more than a few days out, in parts of the world that have little or no ground-level observations.

The study used data from the UW-based WorldWide Lightning Location Network, which has a global record of lightning strikes going back to 2004. Director Holzworth is a plasma physicist who is interested in what happens in the outer edges of the atmosphere. But the network also sells its data to commercial and government agencies, and works with scientists at the UW and elsewhere.

A few years ago Holzworth joined forces with colleagues in the UW Department of Atmospheric Sciences to use lightning to improve forecasts for convective storms, the big storms that produce thunderstorms and tornadoes.

Apart from ground stations, weather forecasts are heavily dependent on weather satellites for information to start or “initialize” the numerical weather prediction models that are the foundation of modern weather prediction.

What’s missing is accurate, real-time information about air moisture content, temperature and wind speed in places where there are no ground stations.

“We have less skill for thunderstorms than for almost any other meteorological phenomenon,” said co-author Cliff Mass, a UW professor of atmospheric sciences. “This paper shows the promise of lightning information. The results show that lightning data has potential to improve high-resolution forecasts of thunderstorms and convection.”

The new method could be helpful in forecasting storms over the ocean, where no ground instruments exist. Better knowledge of lightning-heavy tropical ocean storms could improve weather forecasts far from the equator, Mass said, since many global weather systems originate in the tropics.

The study was funded by NASA and the National Oceanic and Atmospheric Administration. Greg Hakim, a UW professor of atmospheric sciences, is the other co-author. The Worldwide Lightning Location Network began in 2003 with 25 detection sites. It now includes some 80 host sites at universities or government institutions around the world, from Finland to Antarctica.

The latest thinking on how lightning occurs is that ice particles within clouds separate into lighter and heavier pieces, and this creates charged regions within the cloud. If strong updrafts of wind make that altitude separation big enough, an electric current flows to cancel out the difference in charge.

A bolt of lightning creates an electromagnetic pulse that can travel a quarter way around the planet in a fraction of a second. Each lightning network site hosts an 8- to 12-foot antenna that registers frequencies in the 10 kilohertz band, and sends that information to a sound card on an Internet-connected laptop. When at least five stations record a pulse, computers at the UW register a lightning strike, and then triangulate the arrival times at different stations to pinpoint the location.

The network’s online map shows lightning strikes for the most recent 30 minutes in Google Earth. An alternate display shows the last 40 minutes of lightning in different parts of the world on top of NASA cloud maps, which are updated from satellites every 30 minutes. The program is the longest-running real-time global lightning location network, and it is operated by the research community as a global collaboration.

Lightning already kills hundreds of people every year. That threat may be growing — a recent study projected that lightning will become more frequent with climate change.

“The jury’s still out on any long-term changes until we have more data,” Holzworth said. “But there is anecdotal evidence that we’re seeing lightning strikes in places where people are not expecting it, which makes it more deadly.”

On Nov. 19, NASA is scheduled to launch the new GOES-R satellite that will be the first geostationary satellite to include an instrument to continuously watch for lightning pulses. Holzworth will help calibrate the new instrument, which uses brightness to identify lightning, against network data. NASA also funded the recent research as one of the potential applications for lightning observations.

“GOES-R will offer more precise, complete lightning observations over North and South America, which will supplement our global data,” Holzworth said. “This launch has been long anticipated in the lightning research community. It has the potential to improve our understanding of lightning, both as a hazard and as a forecasting tool.”

{As the ancestors of modern humans made their way out of Africa to other parts of the world many thousands of years ago, they met up and in some cases had children with other forms of humans, including the Neanderthals and Denisovans. Scientists know this because traces of those meetings remain in the human genome. Now, researchers reporting in the Cell Press journal Current Biology on November 10 find more evidence that those encounters have benefited humans over the years.}

All told, the new study identifies 126 different places in the genome where genes inherited from those archaic humans remain at unusually high frequency in the genomes of modern humans around the world. We owe our long-lost hominid relatives for various traits, and especially those related to our immune systems and skin, the evidence shows.

“Our work shows that hybridization was not just some curious side note to human history, but had important consequences and contributed to our ancestors’ ability to adapt to different environments as they dispersed throughout the world,” says Joshua Akey of University of Washington School of Medicine in Seattle.

Akey says it’s relatively straightforward today to identify sequences that were inherited from archaic ancestors. Studies show that non-African individuals inherited about 2% of their genomes from Neanderthals. People of Melanesian ancestry inherited another 2% to 4% of their genomes from Denisovan ancestors. But it hasn’t been clear what influence those DNA sequences have had on our biology, traits, and evolutionary history.

In the new study, the researchers took advantage of recently constructed genome-scale maps of Neanderthal and Denisovan sequences identified in more than 1,500 geographically diverse people. Their sample included close to 500 individuals each from East Asia, Europe, and South Asia. They also analyzed the genomes of 27 individuals from Island Melanesia, an area including Indonesia, New Guinea, Fiji, and Vanuatu. The researchers were searching for archaic DNA sequences in those human genomes at frequencies much higher than would be expected if those genes weren’t doing people any good.

While the vast majority of surviving Neanderthal and Denisovan sequences are found at relatively low frequencies (typically less than 5%), the new analyses turned up 126 places in our genomes where these archaic sequences exist at much higher frequencies, reaching up to about 65%. Seven of those regions were found in parts of the genome known to play a role in characteristics of our skin. Another 31 are involved in immunity.

“The ability to increase to such high population frequencies was most likely facilitated because these sequences were advantageous,” Akey explains. “In addition, many of the high-frequency sequences span genes involved in the immune system, which is a frequent target of adaptive evolution.”

Generally speaking, the genes humans got from Neanderthals or Denisovans are important for our interactions with the environment. The evidence suggests that hybridization with archaic humans as our ancient ancestors made their way out of Africa “was an efficient way for modern humans to quickly adapt to the new environments they were encountering.”

The researchers say they’d now like to learn more about how these genes influenced humans’ ability to survive and what implications they might have for disease. They are also interested in expanding their analysis to include geographically diverse populations in other parts of the world, including Africa.