Culture

With its ability to yield parts with complex shapes and minimal waste, additive manufacturing has the potential to revolutionize the production of metallic components. That potential, however, is currently limited by one critical challenge: controlling defects in the process that can compromise the performance of 3D-printed materials.

A new paper in the journal Additive Manufacturing points to a possible breakthrough solution: Use temperature data at the time of production to predict the formation of subsurface defects so they can be addressed right then and there. A team of researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory, together with a colleague now at Texas A&M University, discovered the possibility.

“Ultimately you would be able to print something and collect temperature data at the source and you could see if there were some abnormalities, and then fix them or start over,” said Aaron Greco, group manager for Argonne’s Interfacial Mechanics & Materials group in the Applied Materials Division (AMD) and a study author. “That’s the big-picture goal.”

For their research, the scientists used the extremely bright, high-powered X-rays at beamline 32-ID-B at Argonne’s Advanced Photon Source (APS), a Department of Energy Office of Science User Facility. They designed an experimental rig that allowed them to capture temperature data from a standard infrared camera viewing the printing process from above while they simultaneously used an X-ray beam taking a side-view to identify if porosity was forming below the surface.

Porosity refers to tiny, often microscopic “voids” that can occur during the laser printing process and that make a component prone to cracking and other failures.  

According to Noah Paulson, a computational materials scientist in the Applied Materials division and lead author on the paper, this work showed that there is in fact a correlation between surface temperature and porosity formation below.

“Having the top and side views at the same time is really powerful. With the side view, which is what is truly unique here with the APS setup, we could see that under certain processing conditions based on different time and temperature combinations porosity forms as the laser passes over,” Paulson said.

For example, the paper observed that thermal histories where the peak temperature is low and followed by a steady decline are likely to be correlated with low porosity. In contrast, thermal histories that start high, dip, and then later increase are more likely to indicate large porosity.

The scientists used machine learning algorithms to make sense out of the complex data and predict the formation of porosity from the thermal history. Paulson said that in comparison to the tools developed by tech giants that use millions of data points, this effort had to make do with a couple hundred. “This required that we develop a custom approach that made the best use of limited data,” he said.

While 3D printers typically come equipped with infrared cameras, the cost and complexity make it impossible to equip a commercial machine with the kind of X-ray technology that exists at the APS, which is one of the most powerful X-ray light sources in the world. But by designing a methodology to observe systems that already exist in 3D printers, that wouldn’t be necessary.

“By correlating the results from the APS with the less detailed results we can already get in actual printers using infrared technology, we can make claims about the quality of the printing without having to actually see below the surface,” explained co-author Ben Gould, a materials scientist in the AMD.

The ability to identify and correct defects at the time of printing would have important ramifications for the entire additive manufacturing industry because it would eliminate the need for costly and time-consuming inspections of each mass-produced component. In traditional manufacturing, the consistency of the process makes it unnecessary to scan every metallic component coming off of the production line.

“Right now, there’s a risk associated with 3D printing errors, so that means there’s a cost. That cost is inhibiting the widespread adoption of this technology,” Greco said. “To realize its full potential, we need to lower the risk to lower the cost.”

This effort is made all the more urgent in recognizing one of the key advantages that additive manufacturing has over traditional manufacturing. “We saw with the recent pandemic response how valuable it would be to be able to quickly adapt production to new designs and needs. 3D technology is very adaptable to those kinds of changes,” added Greco.  

Looking ahead, Gould said the research team was hopeful that what he called a “very, very good first step” would allow it to keep improving and expanding the model. “For machine learning, to build accurate models you need thousands and thousands of data points. For this experiment, we had 200. As we put in more data, the model will get more and more exact. But what we did find is very promising.”

Ottawa, August 5, 2020 - Zebrafish are a common aquarium species, of value to hobbyists and scientists alike. Researchers have now engineered an unusual change in them that has echoes of Jurassic Park--but looks alone are deceiving.

A research team studying jaw evolution in the earliest known vertebrates--fishes from around 400 million years ago--have found that a single-gene mutation in the toe-sized zebrafish produced a surprising lookalike of species long extinct.

The phenomenon revealed in their experiments, called developmental plasticity, explains why a real Jurassic Park will continue to remain a distant concept, best suited for cinematic storytelling rather than scientific reality.

"The plasticity we found in the mutants is a key to the great mystery," says Dr. Tetsuto Miyashita, now a palaeontologist at the Canadian Museum of Nature and formerly postdoctoral scholar at the University of Chicago. He led the research team that also included scientists at the Universities of Alberta and Southern California. The results are published today in the Journal of Experimental Biology.

Miyashita is interested in the evolution of key characteristics in vertebrates, of which jaws were one of the first critical developments. "We generally think evolution adds new things. For example, the first jaws evolved in fish 450 million years ago, giving them the ultimate competitive edge over other living creatures. Today, we would starve and suffocate without jaws. But sometimes evolution goes the opposite way. Take away something that's been there for millions of years, and it suddenly opens up new evolutionary directions. My idea is to see it in action."

To do this, Miyashita bred zebrafish that had a mutation in a gene that instructs cells to form a hinge joint of the jaw. The mutant zebrafish are born without a jaw joint so the upper and lower jaws fuse into one - creating a gaping mouth that cannot close. With their wide eyes and gaping mouth, Miyashita reckons they resemble the figure in Edward Munch's artwork "The Scream".

Surprisingly, Miyashita observed that these mutants swimming in the aquarium were able to survive and thrive - despite the lack of a hinged jaw with which to bite. "Instead of gulping for food, the fish chase it until the food ends up in their great gape," says Miyashita. "They seem unable to move the lips or close the mouth - these fish literally have their jaws dropped, fixed in that position."

The researchers observed that the skulls of the jawless mutants were remodelled with a shortened face, expanded cheeks, and massive neck muscles - similar features that first appeared in some of the earliest known jawless fishes during the Silurian and Devonian Periods nearly half a billion years ago.

Known as anaspids and thelodonts, these long-extinct fish that swam in ancient oceans are far removed from the zebrafish's line of ancestry. But like the mutant zebrafish, the fossils of these creatures show that they also lacked biting jaws and presumably had a similar feeding strategy.

It seems like a Jurassic Park moment, as if Miyashita created Devonian jawless fish out of modern ones. But, he explains, there is a more nuanced answer. "The resemblance is more a coincidence than by design. Anaspids and thelodonts are distant cousins half a billion generations removed, " he says. "Zebrafish didn't come from them, so cannot 'go back' to them."

In essence, the mutant zebrafish experiments suggest that genetic engineering does not enable restoring an ancestor. It only allows superficial convergence of characteristics that mutants develop by necessity. "The finding sets an unrealistically high bar for a Jurassic Park-like scenario. Engineered similarities are skin-deep, but origins and contents are completely different."

Miyashita notes the scientific phenomenon of developmental plasticity is why features of extinct organisms sometimes appear in lab-made mutants, as in the highly publicized case of 'dino-chickens.' Although these types of mutants are sometimes referenced as a rewinding of the evolutionary clock, plasticity means they are no more than coincidences.

That said, these initial experiments do offer insights for future scientific research--especially for how extinct jawless fishes (the predecessors of today's fishes) might have fed, breathed, and swam. The mutant zebrafish can be studied by biologists to explore further why evolution makes an occasional "leap". Understanding how jaw fusion occurs in the mutants may also break a path for a new treatment of certain joint diseases.

Miyashita started his new position at the Canadian Museum of Nature April 1, 2020 during the COVID pandemic. This followed post-doctoral work at the University of Chicago where he completed the zebrafish experiments. Scientists at the University of Alberta contributed CT scans and analysis of the skull morphology. Miyashita plans to carry on his work with the mutant zebrafish by establishing another working "Devonian" aquarium at the museum.

Scientists from the University of Adelaide and South Australian Museum have collaborated with Otago University, New Zealand and a global team to sequence the genome of the tuatara - a rare reptile whose ancestors once roamed the earth with dinosaurs.

The findings on this remarkable living, single species reptile, which originated in the Triassic period around 250 million years ago and is only found in New Zealand, have been published in Nature.

Professor David Adelson's lab of the University of Adelaide's Department of Molecular and Biomedical Science and Dr Terry Bertozzi of the South Australian Museum carried out key analysis of the tuatara genome that revealed an unusual architecture, half-way between mammal and reptile.

"The tuatara is the last surviving species of a reptile group that roamed the earth with the dinosaurs and remarkably, its genome shares features with those of mammals such as the platypus and echidna," said Professor Adelson.

The key contribution of Professor Adelson's lab and Dr Bertozzi was to demonstrate that some sequences of DNA that move or jump location, referred to as 'jumping genes', found in the tuatara are most similar to those found in platypus while others are more similar to those in lizards.

"The tuatara genome contained about 4% jumping genes that are common in reptiles, about 10% common in monotremes (platypus and echidna) and less than 1% common in placental mammals such as humans," said Professor Adelson.

"This was a highly unusual observation and indicated that the tuatara genome is an odd combination of both mammalian and reptilian components."

"The unusual sharing of both monotreme and reptile-like repetitive elements is a clear indication of shared ancestry albeit a long time ago," said Dr Bertozzi.

With no close relatives, the position of tuatara on the tree of life has long been contentious. The research places tuatara firmly in the branch shared with lizards and snakes, but they appear to have split off and been their own species for around 250 million years - an enormous amount of time given primates only originated around 65 million years ago, and hominids, from which humans descend, originated approximately six million years ago.

"It has been a privilege to be part of this project, which has been a true, historic collaboration with local iwi (Māori indigenous tribe) Ngātiwai. While this is largely fundamental science, I expect it to yield new ways of thinking about our own genome structure that may have relevance to our health," said Professor Adelson.

Stone fluted points dating back some 8,000 to 7,000 years ago, were discovered on archaeological sites in Manayzah, Yemen and Ad-Dahariz, Oman. Spearheads and arrowheads were found among these distinctive and technologically advanced projectile points. Until now, the prehistoric technique of fluting had been uncovered only on 13,000 to 10,000-year-old Native American sites. According to a study led by an international team of archaeologists from the CNRS (1), Inrap, Ohio State University and the Max Planck Institute for the Science of Human History, the difference in age and geographic location implies there is no connection between the populations who made them. This is therefore an example of cultural convergence for an invention which required highly-skilled expertise. And yet, despite similar fluting techniques, the final aim appears to be different. Whereas in the Americas the points were used to facilitate hafting, or attaching the point to a shaft, fluting in Arabia was possibly a mere display of knapping skills.

What The Study Says: Practice patterns for common ocular complaints during the initial stage of the COVID-19 pandemic are reported in this observational study among comprehensive U.S. ophthalmology practices.

Authors: Ajay E. Kuriyan, M.D., of Mid Atlantic Retina, Wills Eye Hospital, Thomas Jefferson University in Philadelphia, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamaophthalmol.2020.3237)

Editor's Note: The article includes conflict of interest disclosures. Please see the articles for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.

Gastric cancer is the third leading cause of cancer death worldwide, accounting for over 1,000,000 new cases and nearly 800,000 deaths per year. The poor prognosis of gastric cancer is largely due to the difficulty in early diagnosis of peritoneal metastasis.

Separation and characterization of cancer cells are essential for early diagnosis of peritoneal metastasis. However, due to the low content of cancer cells in patients' peritoneal lavages, traditional detection methods lack sensitivity and cannot satisfy clinical demand.

Researchers from the Shenyang Institute of Automation (SIA) of the Chinese Academy of Science (CAS) and City University of Hong Kong (CityU), in cooperation with doctors from the First Hospital of China Medical University, jointly proposed an optically induced electrokinetics (OEK) microfluidic method for label-free separation and characterization of gastric cancer cells.

Their study was published in Science Advances on August 5.

The researchers fabricated a novel OEK-based microfluidic chip to separate live gastric cancer cells from patients' ascites and characterize their electrical properties. They established polymerization model of cells and solution model of cell membrane capacitance.

The sizes and electrical characteristics between the gastric cancer cells and peritoneal lavage cells were significantly different. Thus the OEK method could theoretically separate gastric cancer cells from the ascites and peritoneal lavages.

Through experiments, the researchers separated gastric cancer cells from six patients' ascites with purity up to 71%. Compared with the traditional clinical peritoneal metastasis detection method, this new method solved the problem of low sensitivity.

It is also a label-free, non-destructive and rapid technique. The researchers could separate and collect gastric cancer cells in the OEK microfluidic chip in 5 minutes.

They also obtained the cell membrane capacitances of gastric cancer cells and peritoneal lavage cells. These digital data can be used as a bio-marker, as part of cellular information.

Experimental results in the study demonstrated that the proposed OEK method was capable of detection free cancer cells in ascites and could expedite diagnosis of peritoneal metastasis in gastric cancer.

BOSTON – A paper published today in the Journal of the American Geriatrics Society reported results of an initiative designed to enhance implementation of hospital mobility programs aimed at improving quality of care and outcomes for older patients. Sharon K. Inouye, M.D., M.P.H., Director of the Aging Brain Center in the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife, headed the effort and is the paper’s senior author, and her mentee, Songprod Jonathan Lorgunpai, M.D., Division of Geriatric Medicine, Mount Auburn Hospital, is the paper’s lead author.

Research shows that keeping older hospitalized patients confined to their beds often does more harm than good. Immobility contributes to poor patient outcomes, including increased risk of injurious falls, delirium, aspiration pneumonia, pressure ulcers, functional decline, prolonged length of stay, institutionalization, readmissions, increased healthcare costs, and mortality. Despite this reality, older adults are largely immobilized throughout their hospital stay. According to estimates in 2009 and 2013, patients spent more than 95 percent of their time in a bed or chair.

Protocols in place to prevent falls are a driving force behind this statistic. In 2008, the Centers for Medicare & Medicaid Services enacted new payment provisions that would no longer reimburse hospitals for diagnosis-related groups resulting from hospital-acquired conditions, including falls with injury. As an unintended consequence, many hospitals routinely use bed and chair alarms that discourage mobility as part of their fall prevention programs, despite large randomized clinical trials that have clearly demonstrated bed and chair alarms are ineffective at reducing falls.

As part of a 2016–2017 Health and Aging Policy Fellowship, Dr. Inouye worked with the Center for Medicare & Medicaid Innovation (CMMI) to develop a new care delivery model designed to promote quality improvement related to mobility in hospitals participating in CMMI’s bundled payment programs. The overarching goal of the initiative was to improve mobility and decrease use of bed and chair alarms with hospitalized older adults. To achieve this goal, Dr. Inouye and her team developed a Mobility Action Group (MACT) Change Package that provides a conceptual framework, roadmap, and step-by-step guide to help hospital mobility teams set and meet their mobilization goals.

The MACT Change Package provided more than 40 participating hospitals of varying sizes across the United States with an innovative framework of peer support, expert faculty, and resources to create a successful culture of mobility in the care of hospitalized older adults.

“The Change Package was an essential tool and starting point for each hospital, while the peer support and assistance they received through the group meetings proved to be another key factor in their success,” said Dr. Inouye.

Results indicate that successful implementation of mobility programs was achieved at most (76 percent) participating sites in medical, surgical, and intensive care units, with 43 percent of mobility programs fully implemented and an additional 33 percent partially implemented by the end of the active initiative. Most (54 percent) reported a high likelihood that their mobility program would continue long-term. There was a more than twofold increase in the proportion of patients who received at least three walks per day and a 1.8-fold reduction in the use of bed or chair alarms across sites.

“I’m greatly encouraged by the results of this effort,” said Dr. Lorgunpai, who is also an Instructor in Medicine at Harvard Medical School. “While additional study is needed to determine if this approach can improve patient outcomes such as decreased falls, functional decline, and readmissions, this initiative demonstrates that emphasizing system-wide change through a flexible approach can catalyze a culture of mobility in hospitals and improve care of older adults.”

Additional co-authors include:

Bruce Finke, M.D., Centers for Medicare and Medicaid Services, Department of Health and Human Services, Baltimore;

Isaac Burrows, M.P.H., Centers for Medicare and Medicaid Services, Department of Health and Human Services, Baltimore; Cigna Health and Life Insurance Company, Bloomfield, Conn.;

Cynthia J. Brown, M.D., M.P.H., Division of Gerontology, Geriatrics, and Palliative Care, University of Alabama at Birmingham, Ala; Birmingham/Atlanta Geriatric Research, Education, and Clinical Care Center, Veterans Affairs;

Fred H. Rubin, M.D., Division of Geriatric Medicine, University of Pittsburgh Medical Center Shadyside, Pittsburgh, Penn.;

Heidi R. Wierman, M.D., Division of Geriatric Medicine, Maine Medical Center, Portland, Maine; Tufts University School of Medicine, Boston, Mass.;

Susan J. Heisey, M.S.W., M.P.H., Aging Brain Center, Hinda and Arthur Marcus Institute for Aging Research, Hebrew SeniorLife, Boston, Mass.; Inova Health System, Falls Church, Va.;

Sarah Gartaganis, LIC.S.W., M.P.H., Aging Brain Center, Marcus Institute, Hebrew SeniorLife, Boston, Mass.;

Shari M. Ling, M.D., Centers for Medicare and Medicaid Services, Department of Health and Human Services, Baltimore;

Matthew Press, M.D., M.Sc., University of Pennsylvania Health System, Philadelphia, Penn.

This work was supported in part by the Health and Aging Policy Fellowship, and by technical support from the Hospital Elder Life Program. Dr. Inouye’s time was supported in part by grants no. R24AG054259 (SKI), K07AG041835 (SKI) from the National Institute on Aging, and by the Milton and Shirley F. Levy Family Chair at Hebrew SeniorLife/Harvard Medical School.

About the Hinda and Arthur Marcus Institute for Aging Research
Scientists at the Hinda and Arthur Marcus Institute seek to transform the human experience of aging by conducting research that will ensure a life of health, dignity, and productivity into advanced age. The Marcus Institute carries out rigorous studies that discover the mechanisms of age-related disease and disability; lead to the prevention, treatment, and cure of disease; advance the standard of care for older people; and inform public decision-making. For further information on the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife, please visit https://www.marcusinstituteforaging.org/.

About Hebrew SeniorLife
Hebrew SeniorLife, an affiliate of Harvard Medical School, is a national senior services leader uniquely dedicated to rethinking, researching, and redefining the possibilities of aging. Based in Boston, the nonprofit organization has provided communities and health care for seniors, research into aging, and education for geriatric care providers since 1903. For more information about Hebrew SeniorLife, visit http://www.hebrewseniorlife.org and our blog, or follow us on Facebook, Instagram, Twitter, and LinkedIn.

Journal

Journal of the American Geriatrics Society

For centuries, people around the world have used garlic as a spice, natural remedy, and pest deterrent - but they didn't know how powerful or pungent the heads of garlic were until they tasted them.

Video: https://video.vt.edu/media/1_h08qtb5q

But what if farmers were able to grow garlic and know exactly how potent it would be? What if buyers could pick their garlic based on its might?

A team of Virginia Tech researchers recently discovered a new step in the metabolic process that produces the enzyme allicin, which leads to garlic's delectable flavor and aroma, a finding that upends decades of previous scientific belief. Their work could boost the malodorous - yet delicious - characteristics that garlic-lovers the world over savor.

"This information changes the whole story about how garlic could be improved or we could make the compounds responsible of its unique flavor," said Hannah Valentino, a College of Agriculture and Life Sciences Ph.D. candidate. "This could lead to a new strain of garlic that would produce more flavor."

The discovery of this pathway opens the door for better control of production and more consistent crops, which would help farmers. Garlic could be sold as strong or weak, depending on consumer preferences.

The research was recently published in the Journal of Biological Chemistry.

When Valentino, an Institute for Critical Technology and Applied Science doctoral fellow, and her team set out to test the generally accepted biological process that creates allicin, they found it just didn't happen.

That's when the team of researchers set out to discover what was really happening in garlic.

As they peeled back the layers, they realized there was no fuel to power the previous accepted biological process that creates allicin.

"By using rational design, Hannah found a potential substrate," said Pablo Sobrado, professor of biochemistry in the College of Agriculture and Life Sciences and a member of the research team. "This is significant because by finding the metabolic pathway and understanding how the enzyme actually works and its structure gives us a blueprint of how allicin is created during biosynthesis."

Valentino and the team - which included undergraduate students - worked in the Sobrado Lab in the Fralin Life Sciences Institute directly with the substrates that comprise garlic, doing their work solely in vitro.

Hannah Valentino, left, and Pablo Sobrado, right, are conducting research that is laying the foundation for a future in which buyers can choose garlic based on its strength and flavor profile.

The researchers found that allicin, the component that gives garlic its smell and flavor, was produced by an entirely different biosynthetic process. Allyl-mercaptan reacts with flavin-containing monooxygenase, which then becomes allyl-sulfenic acid.

Importantly, the allicin levels can be tested, allowing farmers to know the strength of their crops without the need for genetic engineering. Greater flavor can simply be predicted, meaning powerful garlic could simply be bred or engineered.

"We have a basic understanding of the biosynthesis of allicin that it is involved in flavor and smell, but we also now understand an enzyme that we can try to modulate, or a modify, to increase or decrease the level of the flavor molecules based on these biological processes," Sobrado said.

Because of their work, the future awaits for fields of garlic harsh enough to keep even the most terrifying vampires at bay.

A new study found solitary activities like fishing, hunting or exploring outside are key to building strong bonds between children and nature. Activities like these encourage children to both enjoy being outside and to feel comfortable there.

In addition to these independent activities, researchers led by an investigator from North Carolina State University reported that they found social activities can help cement the bond between children and nature.

The findings could help children gain the mental and physical benefits linked with being outdoors at a time when researchers say younger generations of Americans may be less connected to nature than before.

"In order to create a strong bond with nature, you need to provide kids with an opportunity to be alone in nature, or to experience nature in a way that they can personally connect with it, but you need to reinforce that with social experiences either with peers or adults," said Kathryn Stevenson, corresponding author of the study and an assistant professor in North Carolina State University's Department of Parks, Recreation and Tourism Management.

For the study, researchers surveyed 1,285 children aged 9 through 12 in North Carolina. The survey focused on identifying the types of activities that help children build a strong connection to nature, which they defined as when children enjoy being outdoors and feel comfortable there.

The researchers asked children about their experiences with outdoor activities such as hunting, fishing, hiking, camping and playing sports, and their feelings about nature overall. The researchers then used children's survey responses to assess which activities were most likely to predict whether they had a strong connection to nature.

While they found that children who participated in solitary activities such as hunting or fishing built strong connections to nature, they also saw that social activities outdoors, such as playing sports or camping, helped to cement the strongest bonds that they saw in children.

"We saw that there were different combinations of specific activities that could build a strong connection to nature; but a key starting point was being outside, in a more solitary activity," Stevenson said.

The finding that solitary activities were important predictors of strong connections to the natural world wasn't surprising given findings from previous research, said Rachel Szczytko, the study's first author. She was previously an environmental education research assistant at NC State, and now works at the San Francisco-based Pisces Foundation.

"We have seen that when people who go into environmentally focused careers reflect on their lives, they describe having formational experiences outdoors during childhood, like walking on a favorite trail or exploring the creek by their home," she said. "We know that these kind of meaningful life experiences are motivating going forward. So we expected that when children are doing something more solitary, contemplative, when they're noticing what's around them, and have a heightened sense of awareness, they are more likely having these formative experiences and are developing more comfort and affinity for the outdoors."

The findings highlight a need to provide more solitary opportunities for kids when they are outside.

"When you think about recreation opportunities for kids, social activities are often covered; people are signing their kids up for sports, camp and scouts," Stevenson said. "Maybe we need more programming to allow children to be more contemplative in nature, or opportunities to establish a personal connection. That could be silent sits, or it could be activities where children are looking or observing on their own. It could mean sending kids to the outdoors to make observations on their own. It doesn't mean kids should be unsupervised, but adults could consider stepping back and letting kids explore on their own."

Researchers said children who are connected to nature are also likely to spend more time outside, which can lead to benefits for children's mental and physical health, attention span and relationships with adults. In addition, researchers said building connections with nature is also important for getting children involved in environmental conservation.

"There are all kinds of benefits from building connections to nature and spending time outside," Stevenson said. "One of the benefits we're highlighting is that children who have a strong connection to nature are more likely to want to take care of the environment in the future."

Researchers at Uppsala University have described the presence, throughout the human body, of the enzyme ACE2. This is thought to be the key protein used by the SARS-CoV-2 virus for host cell entry and development of the disease COVID-19. In contrast to previous studies, the study shows that no or very little ACE2 protein is present in the normal respiratory system. The results are presented in Molecular Systems Biology.

The article presents a large-scale, systematic evaluation of angiotensin I converting enzyme 2 (ACE2) expression in more than 150 cell types, at both messenger RNA (mRNA) and protein levels, and reports that ACE2 is expressed only at very low levels, if at all, in respiratory epithelial cells.

"Considering the clinical manifestations of COVID-19, with acute respiratory distress syndrome and extensive damage to the lung parenchyma, the results highlight the need for further study of the biological mechanisms responsible for COVID-19 infection and disease progression," says Dr Cecilia Lindskog, senior author of the paper and Head Director of the Human Protein Atlas tissue team at Uppsala University.

A full understanding of susceptibility to SARS-CoV-2 infection and its progression to a severe and sometimes deadly disease calls for study of the SARS-CoV-2 entry receptors and their cell-type-specific expression in human tissues, at both mRNA and protein levels. It has been suggested that SARS-CoV-2 employs the enzyme ACE2 for host cell entry, and that penetration of SARS-CoV-2 via this receptor would explain the severe clinical manifestations observed in various tissues and organs, including the respiratory system.

The study by Hikmet et al. presents a comprehensive update on ACE2 expression throughout the human body, at both mRNA and protein levels. Consistently high expression was found in the intestines, kidney, gallbladder, heart, male reproductive organs, placenta, eye and vascular system. In the respiratory system, however, expression was limited, and in a subset of cells in a few individuals there was no or only low expression.

"Previous studies have indicated that ACE2 protein is highly expressed in the human lung. But these expression profiles have not been reliably presented along with tissues and organs from the entire human body, or based on several different datasets at mRNA and protein levels," Lindskog says.

"Here, in contrast to previous studies, we were able to confidently show that no ACE2 protein is present, or that it occurs at only very low levels, in the normal respiratory system."

Immunohistochemical analysis of 360 normal lung samples from an extended patient cohort was based on the Human Protein Atlas (HPA) resource. Two different antibodies, which were stringently validated, were used.

"The HPA programme has devoted considerable efforts to introducing and implementing a new concept for enhanced validation of antibodies, using strategies recommended by the International Working Group for Antibody Validation (IWGAV). Such strategies are crucial for determining whether the antibody staining corresponds to true protein expression," says Professor Mathias Uhlén, Director of the HPA consortium and co-author of the paper.

In a News & Views article published along with the ACE2 paper, Nawijn et al. acknowledge the importance of the study and discuss potential explanations for the low expression in the respiratory system. Recent studies suggest that ACE2 could be an interferon-induced gene, leading to upregulation during SARS-CoV-2 infection. It is proposed that ACE2 may first enter and infect eye conjunctiva and cells in the upper airways, and that this is followed by ACE2 upregulation due to the antiviral response, enabling the SARS-CoV-2 to spread and infect the lung parenchyma. It has also been suggested that smoking may increase ACE2 expression in the respiratory system.

"Further studies addressing the dynamic regulation of ACE2, and to confirm whether the low ACE2 expression in the human respiratory system is sufficient for SARS-CoV-2 infection or whether other factors are needed for host cell entry, are urgently needed," Lindskog says.

An intriguing early symptom among some COVID-19 patients is the loss of the sense of smell and/or taste, which has led to the suspicion that the virus that causes the illness, SARS-CoV-2, could be targeting taste buds. But as researchers report in ACS Pharmacology & Translational Science, initial data from mice suggest that might not be the case. 

Viruses cause infection by invading specific cells in the body and reproducing, often damaging or killing those cells in the process. Research has shown that SARS-CoV-2 enters human cells through angiotensin-converting enzyme 2 (ACE2), a receptor on the surface of some cells, including those of the human tongue. Hong-Xiang Liu and colleagues wanted to find out whether ACE2 was expressed specifically in taste bud cells, as well as when this receptor first emerges on tongue cells during fetal development, by studying mice as a model organism. Although the mouse version of ACE2 isn't susceptible to SARS-CoV-2, studying where it's expressed in mice could help clarify what happens when people become infected and lose the sense of taste. 

By analyzing data from oral cells of adult mice, the researchers found that ACE2 was enriched in cells that give the tongue its rough surface, but couldn't be found in most taste bud cells. That means the virus probably does not cause taste loss through direct infection of these cells, the researchers say. Instead, taste buds might be damaged by inflammation caused by the infection. The team also showed that other viruses that affect taste, including the flu virus, might affect different tongue cell types. Further, the researchers analyzed data from oral cells of mice at three developmental stages and found ACE2 in newborn mice but not in fetuses. Previous studies in humans that were not focused on oral cells suggest ACE2 could be expressed at an early fetal stage and then again at a later stage. Therefore, the team states that fetuses could have distinct susceptibilities to SARS-CoV-2 infection at different stages and more work is needed to determine the timing and location of human ACE2 expression.

Astronomers using several telescopes at NOIRLab, including the Southern Astrophysical Research (SOAR) Telescope, have obtained critical data on a particular type of exploding star that produces copious amounts of calcium. The calcium produced in this unique type of supernova explosion is the same calcium found in our bones and teeth and these events account for up to half of the calcium found in the Universe.

Thanks to detailed observations using the SOAR Telescope, located on Cerro Pachón in Chile, and a host of telescopes around the world and in space [1], astronomers have been able to probe the inner workings of a special type of supernova explosion. These particular explosions, from compact stars that lose copious amounts of mass late in their lives, appear to create the element calcium in their last dying gasps — and it is dispersed by the explosion throughout galaxies like the Milky Way. SOAR is a facility of Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF’s NOIRLab.

“Most massive stars create small amounts of calcium during their lifetimes, but events like SN 2019ehk appear to be responsible for producing vast quantities of calcium and in the process of exploding disperse it through interstellar space within galaxies. Ultimately this calcium makes its way into forming planetary systems,” according to Régis Cartier, an astronomer at NOIRLab and a member of the research team, “…and into our bodies in the case of our Earth!”

Raffaella Margutti, senior author of the study at Northwestern University, adds that prior to this event astronomers had only indirect information on these events, called calcium-rich supernovae. “With this direct evidence, we can now confidently rule out the production of calcium-rich supernovae by the vast majority of massive stars,” said Margutti.

“By observing what this star did in its final month before it reached its critical, tumultuous end, we peered into a place previously unexplored, opening new avenues of study,” said Wynn Jacobson-Galan, of Northwestern University, who led the study. The results are published in the 5 August issue of The Astrophysical Journal, which included contributions from a huge collaboration of nearly 70 co-authors from over 15 countries.

The SOAR data were critical to the result. In particular, the infrared spectrum acquired with SOAR, only the second ever obtained of a calcium-rich supernova, opened a new window on the kind of elements expelled by the supernova — elements such as helium, carbon, magnesium and calcium, all of which have a clear spectral fingerprint at infrared wavelengths. Understanding how much and what kind of elements are expelled by a supernova provides critical clues to the nature of the explosion — what kind of star exploded and how it exploded. It also provides insights into how calcium-rich supernovae produce so much calcium. While that interesting question remains an open issue, the SOAR observations represent some of the first steps toward an answer.

“Because these events are so rare, and difficult to detect because they are faint, we don’t have a lot of data on which to base our theories about what happens as these stars expel material in their death throes,” said Cartier.

The explosive event occurred in the relatively nearby galaxy known as Messier 100 which is a popular target for amateur astronomers and is readily visible through small telescopes. In fact, it was amateur astronomer Joel Shepherd who first spotted the light from the exploding star while stargazing in Seattle on 28 April 2019, and soon thereafter it was designated SN 2019ehk. Messier 100 is a beautiful spiral galaxy similar to our Milky Way and is located some 55 million light-years away towards the constellation of Coma Berenices (Berenice’s Hair) in the northern sky near the constellation of Ursa Major (The Great Bear) which contains the Big Dipper.

According to Jacobson-Galan, once the discovery was announced telescopes around the world and in space were pointed at the exploding star.

Augmenting optical and infrared observations like those by SOAR, X-ray observations revealed a flood of high-energy X-rays from SN 2019ehk — the first time they were observed in a calcium-rich supernova. According to the researchers, nobody had ever thought to look at this type of explosion in X-ray light so soon after it occured.

The combination of observations by SOAR and other telescopes led to the team’s conclusion that this calcium-rich supernova was a compact star that expelled an outer layer of gas as it expired. When it exploded its expelled material collided with surrounding material in its outer shell and the extremely hot temperatures produced X-rays and powered the chemical reactions that make calcium.

The SOAR Telescope’s role in studying this event reflects its evolution toward preparations for the massive Legacy Survey of Space and Time (LSST), which will be carried out at the nearby Vera C. Rubin Observatory, also sited on Cerro Pachón. As SOAR Director Jay Elias explained, “The SOAR Telescope is a flexible platform, designed to be able to respond quickly to unexpected astronomical events like this one. In recent years, SOAR has observed many such transient events discovered by large-area surveys in order to probe the nature of those events. We are continually working to increase the telescope’s efficiency and agility as we prepare for the start of LSST.”

“This type of science, which is critically time-dependent, is an important aspect of where astronomy is heading,” said Edward Ajhar of the US National Science Foundation. “Future facilities such as the Rubin Observatory will discover thousands of transient events like this and will keep astronomers busy making many new discoveries.”

Notes

[1] Post-explosion observations and spectra for this result were also collected by several facilities at NOIRLab observatories including the Bok 2.3-meter Telescope at Kitt Peak National Observatory and Las Cumbres Observatory telescopes at CTIO, as well as at the Neil Gehrels Swift Observatory, the Swope 1-meter telescope at Las Campanas Observatory in Chile, the PlaneWave CDK-700 0.7-meter telescope at Thacher Observatory in California, Las Cumbres Observatory telescopes in South Africa (Sutherland), Australia (Siding Spring, Faulkes Telescope South) and the US (McDonald and Faulkes Telescope North), the ATLAS twin 0.5-meter telescope system in Hawai‘i, the Konkoly Observatory in Hungary, the ESO New Technology Telescope, the MMT Observatory, and the Karl G. Jansky Very Large Array in New Mexico. Pre-explosion data from the Hubble Space Telescope, the Spitzer Space Telescope and the Chandra X-Ray Observatory were also used.

More information

This research was presented in a paper to appear in the 5 August issue of The Astrophysical Journal.

The team is composed of  Wynn V. Jacobson-Galán (Northwestern University and University of California, Santa Cruz), Raffaella Margutti (Northwestern University), Charles D. Kilpatrick (University of California, Santa Cruz), Daichi Hiramatsu (University of California, Santa Barbara and Las Cumbres Observatory), Hagai Perets (Technion – Israel Institute of Technology), David Khatami (University of California, Berkeley), Ryan J. Foley (University of California, Santa Cruz), John Raymond (Center for Astrophysics | Harvard & Smithsonian), Sung-Chul Yoon (Seoul National University), Alexey Bobrick (Lund University), Yossef Zenati (Technion – Israel Institute of Technology), Lluís Galbany (Universidad de Granada), Jennifer Andrews (Steward Observatory), Peter J. Brown (Texas A&M University), Régis Cartier (Cerro Tololo Inter-American Observatory/NOIRLab), Deanne L. Coppejans (Northwestern University), Georgios Dimitriadis (University of California, Santa Cruz), Matthew Dobson (Queen’s University Belfast), Aprajita Hajela (Northwestern University), D. Andrew Howell (University of California, Santa Barbara and Las Cumbres Observatory), Hanindyo Kuncarayakti (University of Turku), Danny Milisavljevic (Purdue University), Mohammed Rahman (The Thacher School), César Rojas-Bravo (University of California, Santa Cruz), David J. Sand (Steward Observatory), Joel Shepherd (Seattle Astronomical Society), Stephen J. Smartt (Queen’s University Belfast), Holland Stacey (The Thacher School), Michael Stroh (Northwestern University), Jonathan J. Swift (The Thacher School), Giacomo Terreran (Northwestern University), Jozsef Vinko (CSFK Konkoly Observatory, University of Szeged, and ELTE Eötvös Loránd University), Xiaofeng Wang (Tsinghua University and Beijing Planetarium), Joseph P. Anderson (European Southern Observatory), Edward A. Baron (University of Oklahoma), Edo Berger (Center for Astrophysics | Harvard & Smithsonian), Peter K. Blanchard (Northwestern University), Jamison Burke (University of California, Santa Barbara and Las Cumbres Observatory), David A. Coulter (University of California, Santa Cruz), Lindsay DeMarchi (Northwestern University), James M. DerKacy (University of Oklahoma), Christoffer Fremling (California Institute of Technology), Sebastian Gomez (Center for Astrophysics | Harvard & Smithsonian), Mariusz Gromadzki (University of Warsaw), Griffin Hosseinzadeh (Center for Astrophysics | Harvard & Smithsonian), Daniel Kasen (University of California, Berkeley and Lawrence Berkeley National Laboratory), Levente Kriskovics (CSFK Konkoly Observatory and ELTE Eötvös Loránd University), Curtis McCully (University of California, Santa Barbara and Las Cumbres Observatory), Tomás E. Müller-Bravo (University of Southampton), Matt Nicholl (University of Birmingham and University of Edinburgh), András Ordasi (CSFK Konkoly Observatory), Craig Pellegrino (University of California, Santa Barbara and Las Cumbres Observatory), Anthony L. Piro (The Observatories of the Carnegie Institution for Science), András Pál (CSFK Konkoly Observatory, ELTE Eötvös Loránd University), Juanjuan Ren (National Astronomical Observatory of China), Armin Rest (Space Telescope Science Institute and The Johns Hopkins University), R. Michael Rich (University of California at Los Angeles), Hanna Sai (Tsinghua University), Krisztián Sárneczky (CSFK Konkoly Observatory), Ken J. Shen (University of California, Berkeley), Philip Short (University of Edinburgh), Matthew Siebert (University of California, Santa Cruz), Candice Stauffer (Northwestern University), Róbert Szakáts (CSFK Konkoly Observatory), Xinhan Zhang (Tsinghua University), Jujia Zhang (Yunnan Astronomical Observatory of China), and Kaicheng Zhang (Tsinghua University).

NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab), the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and the Vera C. Rubin Observatory. It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawaiʻi, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

The Southern Astrophysical Research (SOAR) Telescope, is a joint project of the Ministério da Ciência, Tecnologia e Inovações do Brasil (MCTIC/LNA), NSF’s NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

The Las Cumbres Observatory global telescope network is a non-profit science institute with the mission of advancing science and education has five telescopes between 0.4 and 1.0 meters deployed at CTIO.

The Bok 2.3-meter Telescope at Kitt Peak National Observatory is operated by Steward Observatory at the University of Arizona.

Links

Research paper
Northwestern University release

Contacts:

Wynn Jacobson-GalanNorthwestern UniversityCell: +1 310-966-7779Email: wynnjacobson-galan2024@u.northwestern.edu

Raffaella MarguttiNorthwestern UniversityCell: +1 857-919-6209Email: raffaella.margutti@northwestern.edu

Régis CartierCTIO/NSF’s NOIRLabCell:+56 982 873 645Email: rcartier@ctio.noao.edu

Peter MichaudNewsTeam ManagerNSF’s NOIRLabGemini Observatory, Hilo HICell: +1 808-936-6643Email: pmichaud@gemini.edu

Amanda KoczPress and Internal Communications OfficerNSF’s NOIRLabCell: +1 626 524 5884Email: akocz@aura-astronomy.org

A Brazilian scientist has produced an inventory of 219 pathogens that infect plants in Brazil, including many agriculturally important species. The annotated list, published in Biota Neotropica, is the largest compilation of information on plant viruses ever produced in Brazil. It presents descriptions of the microorganisms, data on the diseases they cause, and information on their occurrence in native, cultivated and ornamental plants as well as weeds.

“Since the start of my career, I’ve been in the habit of collecting publications on plant viruses in Brazil. I’ve been doing it for decades and have recorded some 8,000 references to date,” said the author, Elliot Watanabe Kitajima, a researcher in the Phytopathology and Nematology Department of the University of São Paulo’s Luiz de Queiroz College of Agriculture (ESALQ-USP).

“I eventually realized that if I were asked how many viruses have been recorded in Brazil, I wouldn’t know the answer, so I drew up an alphabetic list of plant species and of the viruses that naturally infect them. I also produced a reverse list in which the viruses and viroids are followed by the plants infected by each one.”

Viroids are the smallest infectious pathogens known to science, consisting of a short strand of RNA with no protein coating. All known viroids are inhabitants of higher plants, and most cause diseases.

Dr. Kitajima graduated in agronomy from ESALQ-USP in 1958 and earned his PhD in 1967 at the same institution. His résumé includes positions as a researcher at the Agronomic Institute (IAC), an agency of the São Paulo State Government, as a professor at the University of Brasília (UnB) and as a visiting professor at his alma mater, where he retired in 2006 and works as a research collaborator.

The inventory is the outcome of projects conducted under the aegis of the FAPESP Research Program on Biodiversity Characterization, Conservation, Restoration and Sustainable Use (BIOTA-FAPESP).

“This review of the viruses documented between 1926 and 2018 basically sums up everything known about plant viruses in Brazil that infect both spontaneous and cultivated vegetation. The author has produced a most important database that will be both useful to researchers and a relevant pest prevention policy input,” said Carlos Joly, a professor at UNICAMP and a member of BIOTA-FAPESP’s steering committee.

Joly also stressed the importance of the inventory to economic activity. “The list includes 346 plant species belonging to 74 different families and the viruses that naturally infect them. Several viruses are listed for such important crops as the citrus group, for example. Many are well known, but others aren’t. In any event, the occurrence of these pathogens affects fruit production and quality. The ability to recognize them quickly can prevent harm and avoid losses,” Joly said.

Most of the viruses and viroids in the inventory are recognized by the International Committee on Taxonomy of Viruses (ICTV), which authorizes and organizes taxonomic classification and nomenclature. Some of the microorganisms listed have yet to be officially recognized. The list maps the history of pathogenic occurrences in Brazilian agriculture and the evolution of plant virology in Brazil as well as the main centers of research in the field.

For example, citrus tristeza virus (CTV) is one of the top 20 viruses in molecular plant pathology. It causes citrus plants to decline quickly and is the most economically important citrus disease worldwide, being responsible for enormous losses, including the destruction of some 10 million orange trees in the 1940s. This problem was solved on the basis of scientific research, and the state of São Paulo became the world’s largest producer and exporter of industrialized orange juice.

Another important crop pest is bean golden mosaic virus, which emerged in the 1970s, when Brazil was one of the world’s leading producers of beans but had to import the commodity from Mexico owing to the severe losses caused by the disease. Additionally, mosaic is caused in papaya by papaya ringspot virus (PRSV). This disease has wiped out entire plantations in Brazil. Control by roguing (systematic removal of diseased plants) has been sufficiently effective to enable the state of Espírito Santo, which pioneered the technique, to become a major exporter of papaya.

“No viruses can be considered more important than others,” Kitajima said. “Several factors, such as geography, climate, plant species or variety, vectors, and crop practices, will determine how hazardous they are. In monocultures with genetic uniformity, viral diseases can spread very quickly if epidemiological conditions are favorable, causing significant losses. This is a hazard growers must always deal with, and we researchers must also be prepared to offer solutions. To this end, we need appropriate information.”

The article “An annotated list of plant viruses and viroids described in Brazil (1926-2018)” by Elliot Watanabe Kitajima can be read at: doi.org/10.1590/1676-0611-BN-2019-0932.

Journal

Biota Neotropica

DOI

10.1590/1676-0611-bn-2019-0932

Equipped with naloxone and a smartphone app, community members can save lives in the fight against America's opioid crisis, according to a paper from researchers at Drexel University's Dornsife School of Public Health and colleagues published this week in The Lancet journal EClinicalMedicine.

During a pilot study, researchers found that enrolled participants were able to signal and respond to opioid overdoses using a smartphone app, called UnityPhilly, developed by the study team. During 22 overdose emergencies, a participant received an overdose alert on the UnityPhilly app, traveled to the location and then administered naloxone to the overdose victim at the scene. In an additional 52 overdose emergencies, the participant who witnessed the overdose signaled an alert with the app and then administered naloxone themselves. A successful reversal was reported in 95.9% (71/74) of cases. In over half of these events (59.5%), study participants administered naloxone more than five minutes faster than Emergency Medical Services (EMS) were able to arrive on scene.

During the year-long observational study, that concluded in February 2020, 112 adult Philadelphians, 57 of whom use opioids, reported 291 suspected overdoses and alerted nearby volunteers using the UnityPhilly app.

All study participants were trained in how to administer naloxone, use the app and give rescue breathing, and then they were provided with two doses of naloxone. Every time an alert was signaled by pressing an "SOS" button in the app, it also alerted EMS via 911 which allowed them to follow up with their protocol, regardless of whether a layperson responded.

"We know that the lay public is effective at administering naloxone, but now we know that an app can help laypersons provide naloxone faster when every second counts," said senior author Stephen Lankenau, PhD, a professor and associate dean for research at the Dornsife School of Public Health who co-led the study with David Schwartz of Bar-Ilan University, Israel. "By empowering community members with these tools, we strengthen the 'chain of survival,' and keep people alive until EMS or other medical personal administer further aid."

Unless it's reversed in time, an overdose from opioids, such as heroin, or pain relievers, like oxycodone or fentanyl, can cause breathing to slow or stop. Naloxone works as an antagonist that connects to opioid receptors to prevent the effects of other opioids in the body. Signs of an overdose include skin feeling cold, blue nails and lips, slow heartbeat and vomiting, among other symptoms.

In 2018, U.S. overdose deaths decreased for the first time in 25 years with 67,367 drug deaths, roughly seven out of 10 involving opioids, but that rate rose nearly 5% to an estimated 72,000 in 2019, according to the Centers for Disease Control and Prevention. The coronavirus pandemic is also suspected of raising overdose deaths and other "deaths of despair." As of July 15, drug deaths are up 13% this year compared to last year, according to government data compiled by The New York Times.

Philadelphia has the highest per capita overdose mortality rate among large U.S. cities, with 1,150 deaths in 2019, a number up 3% from 2018.

The study focused on four Philadelphia zip codes, with participants recruited in the Kensington neighborhood, which experiences higher drug use and availability of naloxone than other areas of the city. The authors will next look at a city-wide study to test if the app can be scaled for all of Philadelphia.

A survey of Central American migrants traveling through Mexico on their way to the United States found that 74 percent of them experienced a degree of food insecurity, ranging from having only one meal to no food at all for one day or longer. Factors associated with more severe food insecurity include more days in active transit, and the experience of illness by the migrant or their travel companion.

This study by researchers at Columbia University Mailman School of Public Health, School of Public Health of Mexico, and the National Institutes of Public Health in Mexico represents the first attempt to document food insecurity in Central American migrants during their overland transit through Mexico. Their findings are published in the Journal of Immigrant and Minority Health.

The researchers interviewed 95 Central American migrants ages 18 and older traveling overland to the U.S. about their experiences of food insecurity in transit. Interviews took place in a migrant shelter (casa del migrante) in north central Mexico near the midway point of the migrant route through Mexico during the month of July. Respondents were overwhelmingly men (73 percent) and relatively young (mean age of 29, but including youth in their late teens as well as middle aged adults), with the largest proportion from Honduras (58 percent).

Lack of Food

More than a third of respondents (35 percent) said they had gone a day or more with only one meal; 19 percent reported a day or more with no meals; and 20 percent reported two or more consecutive days with no food. Food insecurity may even more pronounced further north, as security conditions worsen in proximity to the U.S. border, contributing to even more challenging access to soup kitchen-like facilities and migrant shelters, the researchers note.

The impact of the severe food insecurity noted, can be both acute potentially affecting health during migration (affecting likelihood of exposure to water borne illness), as well as chronic, potentially impacting life after resettlement. "Lack of access to a reliable food supply during the long travel periods and grueling travel conditions imposed on migrants may increase risk for developing upper respiratory or gastrointestinal infections due to lack of access to a clean water supply. Experiences of food insecurity during the trip may compound risks for later chronic health problems and may negatively impact adaptation post migration," the researchers write.

Importantly, the severity of food insecurity noted was particularly remarkable because the authors documented that migrants had experienced two or more consecutive days with no food at all. Standard scales for documenting food insecurity do not presently capture consecutive days of complete lack of food. The physiologic effect of multiple consecutive days with no food intake would be expected to be severe. Such short-term famine probably occurs frequently during migration in other regions of the world as well, yet data on this is not routinely captured.

Illness

In all, 61 percent of respondents said they had experienced a health issue in the prior two weeks, and 28 percent of this group reported an illness that might impede mobility. One in five respondents (20 percent) reported having a chronic health condition prior to migrating. About one-third (32.6 percent) said they traveled with a companion who was ill in the last two weeks.

A migrant's travel companion could be considered the equivalent of the migrants' social support network during the migration journey, the researchers explain. "The association of the travel companion's illness with severity of food insecurity suggests that migrants share responsibility for acquiring food with their travel companion and thus illness by a member of the travel party can be associated with insecurity of the food supply for the group," they write.

The researchers offer a potential remedy to strengthen migrants' access to food: shelters and healthcare facilities could teach migrants about options for procuring nutrition in the next step of their journey with information on locations of organizations providing meals and pointers for obtaining and prioritizing inexpensive, portable, and nourishing food.

"Understanding the factors associated with relative severity of food insecurity during overland migration can inform strategies for prioritizing assistance and prevention," the authors write.

Background on Central American Migrants

According to the United Nations, in 2017, 70,000 people crossed from Mexico to the US, Primarily from El Salvador, Honduras and Guatemala. During their transit through Mexico, migrants are victims of violence and are also affected by environmental factors that may be life threatening. Other harmful exposures include limited access to health care and basic services including food. Migrants may travel for prolonged periods without finding safe resting stops. In Mexico, faith-based organizations have organized shelters (casas del migrante) located strategically along migration routes to the U.S. where migrants receive lodging, food, medical, and legal assistance.

Recent non-violent deaths at the U.S. Mexican border in migrants without known pre-existing medical conditions have highlighted the dangers of this trip, and suggest that the population reaching the U.S. border may be particularly susceptible to illness potentially because of an acutely undernourished state. In 2019 alone, according to the

International Organization for Migration, 530 migrants died on the U.S.-Mexico border, the vast majority of them Central American migrants. The peak periods for these fatalities appear to be during climate extremes: May through July and December and January, suggesting that food procurement could be particularly challenging.