Drug-resistant hospital bacteria persist even after deep cleaning

UNIVERSITY OF CAMBRIDGE

Research News

 

Scientists have used genome sequencing to reveal the extent to which a drug-resistant gastrointestinal bacterium can spread within a hospital, highlighting the challenge hospitals face in controlling infections.

Enterococcus faecium is a bacterium commonly found in the gastrointestinal tract, where it usually resides without causing the host problems. However, in immunocompromised patients, it can lead to potentially life-threatening infection.

Over the last three decades, strains have emerged that are resistant to frontline antibiotics including ampicillin and vancomycin, limiting treatment options - and particularly worrying, these strains are often those found in hospital-acquired E. faecium infections.

A team of scientists at the University of Cambridge and the London School of Hygiene and Tropical Medicine has pioneered an approach combining epidemiological and genomic information to chart the spread of bacteria within healthcare settings. This has helped hospitals identify sources of infection and inform infection control measures.

In a study published today in Nature Microbiology, the team has applied this technique to the spread of drug-resistant E. faecium in a hospital setting.

Dr Theodore Gouliouris from the Department of Medicine at the University of Cambridge, and joint first author on the study, said: "We've known for over two decades that patients in hospital can catch and spread drug-resistant E. faecium. Preventing its spread requires us to understand where the bacteria lives - its 'reservoirs' - and how it is transmitted.

"Most studies to date have relied on culturing the bacteria from samples. But as we've shown, whole genome sequencing - looking at the DNA of the bacteria - combined with detailed patient and environmental sampling can be a powerful tool to help us chart its spread and inform ways to prevent further outbreaks."

The team followed 149 haematology patients admitted to Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, over a six-month period. They took stool samples from the patients and swabs from the hospital environment and cultured them for E. faecium.

Genomic analysis of the bacteria was much more effective at identifying hospital-acquired E. faecium: out of 101 patients who could be followed up, genomic analysis identified that two thirds of patients acquired E. faecium, compared to less than half using culture methods alone.

Just under half (48%) of the swabs taken from the hospital environment were positive for vancomycin-resistant E. faecium. This included 36% of medical devices, 76% of non-touch areas such as air vents, 41% of bed spaces and 68% of communal bathrooms tested.

The researchers showed that even deep cleaning could not eradicate the bacteria. The hospital undertook deep cleaning on one ward over a three-day period during the study, when patients were moved elsewhere; however, when the team sampled locations prior to patients returning to the ward, they found that 9% of samples still tested positive for the bacteria. Within three days of patients returning to the ward, around half of the sampled sites tested positive.

Three-quarters (74%) of the patients (111/149) were carriers of the A1 clade - a multi-drug resistant strain of E. faecium commonly seen in hospitals that is resistant to the antibiotic ampicillin and which frequently acquires resistance to vancomycin. Of these 111 patients, 67 had strong epidemiological and genomic links with at least one other patient and/or their direct environment.

"The fact that these cases were all linked to another patient or their environment suggests strongly that they had picked up the multi-drug resistant bacteria while in the hospital," said Dr Francesc Coll from the London School of Hygiene and Tropical Medicine, joint first author.

Further genomic analysis showed that within this multi-drug resistant strain were several subtypes (defined by how genetically-similar they were). However, it was not uncommon for a patient to be carrying more than one subtype, which - without detailed genomic analysis - could confound attempts to identify the route of transmission of an infection. Notably, despite the circulation of as many as 115 subtypes, 28% of E. faecium acquisitions were caused by just two superspreading subtypes. The authors found no evidence of resistance or tolerance to common disinfectants to explain the success of these subtypes.

Six study patients contracted an 'invasive infection', meaning that they had been carrying E. faecium asymptomatically in their gut, but subsequently developed a symptomatic infection. Comparing the genomes of the infecting and gut strains the authors determined that invasive E. faecium infections originated from the patients' own gut.

"Our study builds on previous observations that drug-resistant strains of E. faecium can persist in the hospital environment despite standard cleaning - we were still surprised to find how short-lasting was the effect of deep cleaning," added Dr Gouliouris.

"We found high levels of hospital-adapted E. faecium despite the use of cleaning products and procedures that have proven effective against the bug. It highlights how challenging it can be to tackle outbreaks in hospitals."

Senior author Professor Sharon Peacock from the Department of Medicine at the University of Cambridge added: "The high rates of infection with drug-resistant E. faecium in specific vulnerable patient groups and its ability to evade cleaning measures pose an important challenge to infection control. Patient screening, adequate provision of isolation and ensuite toilet facilities, improved and more frequent cleaning procedures, and stricter health-care worker hygiene practices will all be needed to curtail this global epidemic.

"But this is also a sign of how urgently we need to tackle inappropriate use of antibiotics worldwide, which is widely recognised as posing a catastrophic threat to our health and our ability to control infections."

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The research was funded by the Department of Health and Wellcome.

Reference
Gouliouris, T, Coll, F et al. Quantifying acquisition and transmission of Enterococcus faecium using genomic surveillance. Nature Microbiology; 26 Oct 2020; DOI: 10.1038/s41564-020-00806-7

 

Tiny golden bullets could help tackle asbestos-related cancers

UNIVERSITY OF CAMBRIDGE

Research News

 

IMAGE: CONFOCAL FLUORESCENCE IMAGE OF GOLD NANOTURES (GREEN) IN MESOTHELIOMA CELLS view more 

CREDIT: ARSALAN AZAD

Gold nanotubes - tiny hollow cylinders one thousandth the width of a human hair - could be used to treat mesothelioma, a type of cancer caused by exposure to asbestos, according to a team of researchers at the Universities of Cambridge and Leeds.

In a study published today in journal Small, the researchers demonstrate that once inside the cancer cells, the nanotubes absorb light, causing them to heat up, thereby killing the cells.

More than 2,600 people are diagnosed in the UK each year with mesothelioma, a malignant form of cancer caused by exposure to asbestos. Although the use of asbestos is outlawed in the UK now, the country has the world's highest levels of mesothelioma because it imported vast amounts of asbestos in the post-war years. The global usage of asbestos remains high, particularly in low- and middle-income countries, which means mesothelioma will become a global problem.

"Mesothelioma is one of the 'hard-to-treat' cancers, and the best we can offer people with existing treatments is a few months of extra survival," said Dr Arsalan Azad from the Cambridge Institute for Medical Research at the University of Cambridge. "There's an important unmet need for new, effective treatments."

In 2018, the University of Cambridge was awarded £10million from the Engineering and Physical Sciences Research Council to help develop engineering solutions, including nanotech, to find ways to address hard-to-treat cancers.

In a collaboration between the University of Cambridge and University of Leeds, researchers have developed a form of gold nanotubes whose physical properties are 'tunable' - in other words, the team can tailor the wall thickness, microstructure, composition, and ability to absorb particular wavelengths of light.

The researchers added the nanotubes to mesothelioma cells cultured in the lab and found that they were absorbed by the cells, residing close to the nucleus, where the cell's DNA lies. When the team targeted the cells with a laser, the nanotubes absorbed the light and heated up, killing the mesothelioma cell.

Professor Stefan Marciniak, also from the Cambridge Institute for Medical Research, added: "The mesothelioma cells 'eat' the nanotubes, leaving them susceptible when we shine light on them. Laser light is able to penetrate deep into tissue without causing damage to surrounding tissue. It then gets absorbed by the nanotubes, which heat up and, we hope in the future, could be used to cause localised cancer-cell killing."

The team will be developing the work further to ensure the nanotubes are targeted to cancer cells with less effect on normal tissue.

The nanotubes are made in a two-step process. First, solid silver nanorods are created of the desired diameter. Gold is then deposited from solution onto the surface of the silver. As the gold builds-up at the surface, the silver dissolves from the inside to leave a hollow nanotube.

The approach advanced by the Leeds team allows these nanotubes to be developed at room temperature, which should make their manufacture at scale more feasible.

Professor Stephen Evans from the School of Physics and Astronomy at the University of Leeds said: "Having control over the size and shape of the nanotubes allows us to tune them to absorb light where the tissue is transparent and will allow them to be used for both the imaging and treatment of cancers. The next stage will be to load these nanotubes with medicines for enhanced therapies."

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The research was funded by the British Lung Foundation, Victor Dahdaleh Foundation, National Institute for Health Research Cambridge Biomedical Research Centre, Royal Papworth Hospital, Alpha1-Foundation, Medical Research Council and the Engineering & Physical Sciences Research Council.

Reference

Ye, S & Azad, AA et al. Exploring High Aspect Ratio Gold Nanotubes as Cytosolic Agents: Structural Engineering and Uptake into Mesothelioma Cells. Small; 25 Oct 2020: DOI: 10.1002/smll.2003793

 

Air pollution, green space and built environment characteristics may influence body mass index durin

BARCELONA INSTITUTE FOR GLOBAL HEALTH (ISGLOBAL)

Research News

 

Exposure to higher air pollution levels and greater population density during the early months of life may be associated with an increase in children's body mass index (BMI). By contrast, living in areas with greater exposure to green space and a more favourable land use mix (a measure of the variety of building types and services in an area) could be associated with the opposite effect. These are two conclusions reached by a study undertaken by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Foundation, in which data from nearly 80,000 children living in urban environments in Catalonia was, for the first time, analysed to explore relationships between BMI growth trajectories and multiple urban exposures.

There is a growing body of evidence that environmental urban exposures, such as air pollution, green space and the built environment, may be linked to effects on growth and obesity in children. These effects may begin at a very early stage, during pregnancy and the first few years of life. "Urban environments are characterised by multiple exposures that may influence the BMI, but the results of research to date have been inconsistent and earlier studies did not assess simultaneous exposures," explains the first author of the study, Jeroen de Bont, researcher at ISGlobal and the IDIAPJGol Foundation.

The most notable innovation of this new large scale longitudinal study, funded by the La Marató de TV3 Foundation and published in the journal Environmental Pollution, was that multiple exposures were evaluated simultaneously. The data analysed was extracted from a database of primary care medical records in Catalonia, which included 79,992 children born between 2011 and 2012 in urban areas, who were followed up until they reached five years of age. BMI growth curves were calculated based on routine measurements of weight and height. At the same time, the authors estimated various urban exposures at the level of the census tracts where the children live. These included air pollution (nitrogen dioxides [NO2] and particulate matter [PM10 and PM2.5], green spaces and several characteristics of the built environment (population density, street connectivity, land use, and walkability).

"Our results suggest that the population density in urban areas and exposure to higher levels of air pollution may be associated with a small increase in BMI in children up to five years of age and that greater exposure to green spaces and a more favourable land use mix may be associated with a small decrease in BMI," says de Bont. "The fact that these associations were strongest during the first two months of life," he adds, "could be explained by the effects of exposure during pregnancy, which would persist over time".

According to study coordinator and ISGlobal researcher Martine Vrijheid, earlier findings indicated that the relationship between BMI and air pollution might be explained by the fact that the pollution "could affect foetal growth through various factors, such as oxidative stress and inflammation, and lead to alterations in the basal metabolism of infants, thereby increasing the risk of obesity by inducing insulin resistance and hormonal alterations".

"On the other hand," Vrijheid goes on to explain, "the possible relationship between a lower BMI and exposure to green space could be explained by the fact that such spaces are a valuable resource favouring physical activity on the part of both mother and child and result in a beneficial effect on the development of the foetus and later on that of the child".

A different hypothesis is that the association could be explained by another possible mediating factor--the lower levels of air pollution observed in the greener areas in the study.

In the case of the characteristics of the built environment, Vrijheid goes on to explain that higher population density may be associated with a higher BMI "owing to higher levels of air pollution and because traffic levels in the more populated areas in Spain may give rise to a perceived lack of safety and disincentivise active modes of travel (walking and cycling), thereby increasing childhood obesity."

While there is no clear consensus on how the land use mix affects BMI, the chief hypothesis is that a more varied land use mix decreases the distance between housing, work and services and therefore favours walking and cycling, which in turn increases levels of physical activity.

"For children, the early years of life are a time of great sensitivity; they represent a window of special vulnerability to environmental exposures that can permanently affect the structure, physiology and metabolism of the child's body. Future studies should take into account multiple exposures in the urban setting instead of analysing exposure one by one, as encouraged by the exposome concept, which studies many different exposures a person faces altogether", Vrijheid concludes.

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Reference

Jeroen de Bont, Rachael Hughes, Kate Tilling, Yesika Díaz, Montserrat de Castro, Marta Cirach, Serena Fossati, Mark Nieuwenhuijsen, Talita Duarte-Salles, Martine Vrijheid. Early life exposure to air pollution, green spaces and built environment, and body mass index growth trajectories during the first 5 years of life: A large longitudinal study. Environmental Pollution. July 2020. https://doi.org/10.1016/j.envpol.2020.115266.

 

Neuron-based gene expression study reveals insights on fear and its regulation

Researchers identify potential therapeutic target for fear-based psychiatric illnesses

MCLEAN HOSPITAL

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IMAGE: RESEARCHER LED BY A TEAM AT MCLEAN HAS FOUND A POTENTIAL NEW TARGET FOR DIAGNOSING, TREATING, AND PREVENTING FEAR-RELATED PSYCHIATRIC ILLNESSES view more 

CREDIT: MCLEAN HOSPITAL

Highlights

• The expression of a gene called CREB in certain neurons may function as a switch to regulate feelings of fear and its extinction.
• Targeting this gene may provide new information and treatments for fear-based psychiatric conditions.

Fear and fear extinction learning (the gradual reduction of fear by repeated exposure to the feared object) are adaptive processes caused by molecular changes in specific brain circuits, and they're perturbed in conditions such as anxiety and post-traumatic stress disorder. A new study by investigators at McLean Hospital and Massachusetts General Hospital reveals that the expression of a particular gene may function as a switch to regulate feelings of fear and its extinction. The findings point to a potential new target for diagnosing, treating, and preventing fear-related psychiatric illnesses.

The research, which is published in Nature Communications, focuses on neurons in the central amygdala that produce a corticotropin-releasing hormone (Crh) and are involved in the brain's response to threats. The scientists examined how different gene pathways are activated within Crh neurons after the expression or extinction of fear.

"This precise analysis utilized a new cell-type-specific technology called translating ribosome affinity purification, or TRAP, to identify gene expression only within the Crh amygdala cells," said co-senior author Nikolaos P. Daskalakis, MD, PhD, who is the director of the Neurogenomics and Translational Bioinformatics Laboratory at McLean Hospital. "The results showed that diverse gene networks are activated or inhibited by fear versus extinction learning."

Additional analyses demonstrated that fear extinction learning requires that Crh neurons reduce their expression of a regulatory gene named CREB, which codes for a protein called cAMP response-element binding protein. Indeed, overexpression of CREB in Crh neurons in mice increased their fear response.

"CREB is well known to be involved in learning and memory, and these data suggest that it may act as a molecular switch that regulates expression of fear and its extinction," said co-senior author Kerry J. Ressler, MD, PhD, McLean's chief scientific officer, McLean's chief of the Center of Excellence in Depression and Anxiety Disorders, and co-director of the Silvio O. Conte Center for Stress Peptide Advanced Research, Education & Dissemination (SPARED) at McLean Hospital.

Targeting CREB expression in Crh neurons in the brain's amygdala may provide a better understanding of the mechanisms behind fear-based psychiatric illnesses and represent a promising treatment strategy.

"Fear is one of the most basic emotions we all experience in response to trauma--and also one of the most complex to study," says Magali Haas, MD, PhD, CEO and president of Cohen Veterans Bioscience, the nonprofit biotech research organization fast-tracking diagnostics and therapeutics for trauma-related and other brain disorders. "We are proud to support this latest research into how animal models' brains process fear, which could provide important parallels in humans and lead to new ways to diagnose or treat disorders such as PTSD."

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Funding sources: This work was supported by funding from Cohen Veterans Bioscience, NIMH (P50-MH115874, R01-MH108665, R01-MH117292, and R01-MH063266), and the Frazier Institute at McLean Hospital. C.C. was supported by the 2019 SPARED Center Seed Grant (through NIMH P50-MH115874). N.P.D. was supported by a NARSAD Young Investigator grant and an appointed KL2 award from Harvard Catalyst/The Harvard Clinical and Translational Science Center (NCATS KL2TR002542 and UL1TR002541).

ABOUT McLEAN HOSPITAL:

McLean Hospital has a continuous commitment to put people first in patient care, innovation and discovery, and shared knowledge related to mental health. It is consistently named the #1 freestanding psychiatric hospital in the United States by U.S. News & World Report. McLean Hospital is the largest psychiatric affiliate of Harvard Medical School and a member of Mass General Brigham. To stay up to date on McLean, follow us on Facebook, YouTube, and LinkedIn.

ABOUT COHEN VETERANS BIOSCIENCE:

Cohen Veterans Bioscience (CVB) is a nonprofit (501)(c)(3) research biotech dedicated to fast-tracking the development of diagnostic tests and personalized therapeutics for the millions of veterans and civilians who suffer from the devastating effects of trauma-related and other brain disorders.

To learn more about CVB's research efforts, visit: http://www.cohenveteransbioscience.org

 

Bridges with limb-inspired architecture can withstand earthquakes, cut repair costs

Using expert feedback, Texas A&M researchers quantify the benefits of their new bridge design

TEXAS A&M UNIVERSITY

Research News

 

IMAGE: SPECIMEN OF THE HYBRID SLIDING-ROCKING BRIDGE COLUMN TESTED IN THE CENTER FOR INFRASTRUCTURE RENEWAL'S LARGE-SCALE EXPERIMENTAL FACILITIES. view more 

CREDIT: TEXAS A&M UNIVERSITY COLLEGE OF ENGINEERING

Structural damage to any of the nation's ailing bridges can come with a hefty price of billions of dollars in repairs. New bridge designs promise more damage-resistant structures and, consequently, lower restoration costs. But if these designs haven't been implemented in the real world, predicting how they can be damaged and what repair strategies should be implemented remain unresolved.

In a study published in the journal Structure and Infrastructure Engineering, Texas A&M University and the University of Colorado Boulder researchers have conducted a comprehensive damage and repair assessment of a still-to-be-implemented bridge design using a panel of experts from academia and industry. The researchers said the expert feedback method offers a unique and robust technique for evaluating the feasibility of bridge designs that are still at an early research and development phase.

"Bridges, particularly those in high-seismic regions, are vulnerable to damage and will need repairs at some point. But now the question is what kind of repairs should be used for different types and levels of damage, what will be the cost of these repairs and how long will the repairs take -- these are all unknowns for new bridge designs," said Dr. Petros Sideris, assistant professor in the Zachry Department of Civil and Environmental Engineering. "We have answered these questions for a novel bridge design using an approach that is seldomly used in structural engineering."

Most bridges are monolithic systems made of concrete poured over forms that give the bridges their shape. These bridges are strong enough to support their own weight and other loads, such as traffic. However, Sideris said if there is an unexpected occurrence of seismic activity, these structures could crack, and remedying the damage would be exorbitantly expensive.

To overcome these shortcomings, Sideris and his team have developed a new design called a hybrid sliding-rocking bridge. Instead of a monolithic design, these bridges are made of columns containing limb-inspired joints and segments. Hence, in the event of an earthquake, the joints allow some of the energy from the ground motion to diffuse while the segments move slightly, sliding over one another rather than bending or cracking. Despite the overall appeal of the hybrid sliding-rocking bridge design, little is known about how the bridges will behave in real-world situations.

"To find the correct repair strategy, we need to know what the damages look like," said Sideris. "Our bridge design is relatively new and so there is little scientific literature that we could refer to. And so, we took an unconventional approach to fill our gap in knowledge by recruiting a panel of experts in bridge damage and repair."

For their study, Sideris, Dr. Abbie Liel, professor at the University of Colorado, Boulder, and their team recruited a panel of eight experts from industry and academia to determine the damage states in experimentally tested hybrid sliding-rocking segment designed columns. Based on their evaluations of the observed damage, the panel provided repair strategies and estimated costs for repair. The researchers then used that information to fix the broken columns, retested the columns under the same initial damage-causing conditions and compared the repaired column's behavior to that of the original column through computational investigations.

The panel found that columns built with their design sustained less damage overall compared to bridges built with conventional designs. In fact, the columns showed very little damage even when subject to motions reminiscent of a powerful once-in-a-few-thousand-years earthquake. Furthermore, the damage could be repaired relatively quickly with grout and carbon fibers, suggesting that no special strategy was required for restoration.

"Fixing bridges is a slow process and costs a significant amount of money, which then indirectly affects the community," said Sideris. "Novel bridge designs that may have a bigger initial cost for construction can be more beneficial in the long run because they are sturdier. The money saved can then be used for helping the community rather than repairing infrastructure."

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This work is funded by the National Science Foundation.

Other contributors include Dr. Jakub Valigura, former graduate student researcher from the University of Colorado Boulder and Dr. Mohammad Salehi, former graduate student in the civil and environmental engineering department at Texas A&M.

 

Dog training methods help JHU teach robots to learn new tricks

JOHNS HOPKINS UNIVERSITY

Research News

 

IMAGE:  "THE QUESTION HERE WAS HOW DO WE GET THE ROBOT TO LEARN A SKILL? " SAID LEAD AUTHOR ANDREW HUNDT, A PHD STUDENT WORKING IN JOHNS HOPKINS' COMPUTATIONAL INTERACTION AND ROBOTICS... view more 

CREDIT: WILL KIRK/JOHNS HOPKINS UNIVERSITY

With a training technique commonly used to teach dogs to sit and stay, Johns Hopkins University computer scientists showed a robot how to teach itself several new tricks, including stacking blocks. With the method, the robot, named Spot, was able to learn in days what typically takes a month.

By using positive reinforcement, an approach familiar to anyone who's used treats to change a dog's behavior, the team dramatically improved the robot's skills and did it quickly enough to make training robots for real-world work a more feasible enterprise. The findings are newly published in a paper called, "Good Robot!"

"The question here was how do we get the robot to learn a skill?" said lead author Andrew Hundt, a PhD student working in Johns Hopkins' Computational Interaction and Robotics Laboratory. "I've had dogs so I know rewards work and that was the inspiration for how I designed the learning algorithm."

Unlike humans and animals that are born with highly intuitive brains, computers are blank slates and must learn everything from scratch. But true learning is often accomplished with trial and error, and roboticists are still figuring out how robots can learn efficiently from their mistakes.

The team accomplished that here by devising a reward system that works for a robot the way treats work for a dog. Where a dog might get a cookie for a job well done, the robot earned numeric points.

Hundt recalled how he once taught his terrier mix puppy named Leah the command "leave it," so she could ignore squirrels on walks. He used two types of treats, ordinary trainer treats and something even better, like cheese. When Leah was excited and sniffing around the treats, she got nothing. But when she calmed down and looked away, she got the good stuff. "That's when I gave her the cheese and said, 'Leave it! Good Leah!'"

Similarly, to stack blocks, Spot the robot needed to learn how to focus on constructive actions. As the robot explored the blocks, it quickly learned that correct behaviors for stacking earned high points, but incorrect ones earned nothing. Reach out but don't grasp a block? No points. Knock over a stack? Definitely no points. Spot earned the most by placing the last block on top of a four-block stack.

The training tactic not only worked, it took just days to teach the robot what used to take weeks. The team was able to reduce the practice time by first training a simulated robot, which is a lot like a video game, then running tests with Spot.

"The robot wants the higher score," Hundt said. "It quickly learns the right behavior to get the best reward. In fact, it used to take a month of practice for the robot to achieve 100% accuracy. We were able to do it in two days."

Positive reinforcement not only worked to help the robot teach itself to stack blocks, with the point system the robot just as quickly learned several other tasks - even how to play a simulated navigation game. The ability to learn from mistakes in all types of situations is critical for designing a robot that could adapt to new environments.

"At the start the robot has no idea what it's doing but it will get better and better with each practice. It never gives up and keeps trying to stack and is able to finish the task 100% of the time," Hundt said.

The team imagines these findings could help train household robots to do laundry and wash dishes - tasks that could be popular on the open market and help seniors live independently. It could also help design improved self-driving cars.

"Our goal is to eventually develop robots that can do complex tasks in the real world -- like product assembly, caring for the elderly and surgery," Hager said. "We don't currently know how to program tasks like that -- the world is too complex. But work like this shows us that there is promise to the idea that robots can learn how to accomplish such real-world tasks in a safe and efficient way."

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The team and co-authors included Johns Hopkins graduate students Andrew Hundt, Benjamin Killeen, Nicholas Greene, Heeyeon Kwon, and Hongtao Wu; former graduate student Chris Paxton; and Gregory D. Hager, the Mandell Bellmore Professor of Computer Science.

 

State gun laws may help curb violence across state lines: study

COLUMBIA UNIVERSITY'S MAILMAN SCHOOL OF PUBLIC HEALTH

Research News

 

Columbia University Mailman School of Public Health researchers find that strong state firearm laws are associated with fewer firearm homicides--both within the state where the laws are enacted and across state lines. Conversely, weak firearm laws in one state are linked to higher rates of homicides in neighboring states.

Results of the study appear in the journal Epidemiology, and are based on an analysis of county-level data on firearm homicides as they relate to state gun laws between 2000 and 2014.

Around 14,000 Americans civilians die and over 75,000 people are treated in emergency departments because of gun violence every year. This study adds evidence that the count and composition of states' gun laws affect within-state homicide incidence. The associations are strongest for background checks compared to other gun laws, including child access prevention laws, dealer registration laws, and licensing laws. As well as examining within-state effects, the research is one of the few studies to explore the potential effects of gun laws on homicides in neighboring states, with the results emphasizing that firearm laws spill over state lines.

The study found that homicide incidence was greatest in counties with weak within-state laws and where the largest nearby population centers were in other states that also weak laws. As an example, the researchers contrast New Hampshire and Alabama, which both had 10 gun laws in 2014. The most populous urban center near New Hampshire is Boston, which had 100 gun laws, whereas the major city nearest to Alabama is Atlanta, where there were 6 laws. The weak gun laws in Alabama and Georgia both contribute to higher homicide incidence in Alabama, but the stronger gun laws in Massachusetts temper the effect of the weak laws in New Hampshire. To explain these results, the researchers suggest it may be easier for guns to flow undetected into places where laws are already weak.

"Gun violence is a public health crisis in the United States," says first author Christopher Morrison, PhD, Assistant Professor of epidemiology at the Columbia Mailman School. "Research has demonstrated that strong gun laws can reduce this burden. It's now becoming clear that weak gun laws don't only drive up gun violence within their own borders, they also affect gun violence in neighboring states."

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Study authors include Christopher N. Morrison; Elinore J. Kaufman and Douglas J. Wiebe of the University of Pennsylvania; and David K. Humphreys of the University of Oxford.

The study was supported in part by the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health (AA026327).

 

New lead screening method zooms in on highest-risk areas in Georgia

The method could be applied to any area in the United States

EMORY HEALTH SCIENCES

Research News

 

IMAGE: 

SCREENING INDEX SCORES FOR LOW-LEVEL LEAD EXPOSURE IN GEORGIA. CLICK HERE TO SEE AN INTERACTIVE VERSION OF THE MAP: http://scholarblogs.emory.edu/esaikawa/files/2020/10/GA_map.html

... view more 

CREDIT: SAIKAWA LAB, EMORY UNIVERSITY

While many people think of lead poisoning as a problem of the past, chronic exposure still occurs in some communities that may be missed in limited screening programs for children's blood lead levels. Now researchers at Emory University have developed a more precise screening index, illustrated with a map, which provides a fine-grain view of areas where children are most at risk for low-level lead exposure in the city of Atlanta and throughout the state of Georgia.

Scientific Reports published their new method, including analyses that tested and showed its efficacy, using historical data.

The new screening index is based on established risk factors for lead exposure, including poverty and housing built before 1950. The index pinpointed 18 highest-priority census tracts in metro Atlanta, encompassing 2,715 children under the age of six -- or 1.7 percent of all children that age in greater Atlanta.

These highest-priority areas include the historically black neighborhoods of English Avenue and Vine City, where Emory researchers had previously identified elevated levels of lead in the soil of some yards and vacant lots.

"As we move forward into an age when acute lead poisoning is rare, we need better tools to monitor for chronic, long-term exposure to lead," says Emory graduate Samantha Distler, first author of the paper. "We developed an interactive map that can be used by physicians and other health officials, and even by individuals who want to check their own children's risk levels. You can easily zoom in to find an exact location, so there's less guess work involved in assessing what is a high-risk area."

The method could be applied to any area in the United States, she adds.

Distler led the work as an Emory undergraduate majoring in quantitative sciences on the neuroscience and behavioral biology track. She is now a graduate student of epidemiology at the University of Michigan School of Public Health.

"Lead is a toxicant that is particularly dangerous to children and their developing brains," Distler says. "Even low blood lead levels are associated with neurological deficits in children."

"One of the biggest problems concerning lead is that many people don't know if their children are being exposed," says Eri Saikawa, senior author of the study and associate professor in Emory's Department of Environmental Sciences and Rollins School of Public Health. "Detecting lead exposure as early as possible is very important so preventative measures can be taken. The easiest way to do that is to screen the blood."

In 2018, the Saikawa lab collaborated with members of Atlanta's Historic Westside Gardens to test urban soil on Atlanta's Westside for contaminants. That project uncovered high levels of heavy metal and metalloids in some yards, and even some industrial waste known as slag. The project led to an investigation by the U.S. Environmental Protection Agency, which in 2019 began decontaminating properties in the area by removing and replacing soil.

In addition to neurological deficits, lead exposure is associated with immunological and endocrine effects and cardiovascular disease. Decades ago, federal regulations reduced lead in paint and gasoline and other common exposure sources. The resulting drop in children's blood lead levels in the United States is considered one of the greatest public health achievements in the country's history.

Many people remain unaware, however, that lead persists in the environment. "It can linger for a really long time in everything from soil to water," Distler says. "That puts some people at risk for chronic exposures to low levels over a long time."

The Centers for Disease Control and Prevention (CDC) estimates that at least four million households in the United States have children living in them who are being exposed to high levels of lead. And about half a million of those children aged one to five years have blood lead levels above five micrograms per deciliter, the level at which the CDC recommends initiating public health action.

Despite this alarming statistic, many children in higher-risk areas are not screened for blood lead levels. In Georgia, data from the period 2011 to 2018 show that the proportion in various ZIP code tabulation areas who have been tested range from 1 percent to 67 percent, with a median of 13 percent.

The Emory researchers realized that one problem may be that health officials focus screening efforts on a county-wide basis, rather than zeroing in on the highest-risk neighborhoods within those counties.

In 2009, a team led by researchers at the CDC developed and published a priority screen index for Atlanta neighborhoods based on housing age and percentage of residents enrolled in Georgia's Special Supplemental Nutrition Program for Women, Infants and Children (WIC), a proxy for poverty.

For the current paper, the Emory researchers built on the efforts of the 2009 paper, drilling down from neighborhoods to more precise U.S. Census Bureau tracts. Data from the American Community Survey was used to assess the relative level of poverty and proportion of homes built before 1950.

A priority screening index, ranging from two to eight, was applied to the census tracts. The areas of highest relative poverty and proportion of homes built before 1950 received the highest score. The researchers applied this index to census tracts across the state of Georgia and to the entire United States to identify tracts that consistently have the highest priority screening index values.

"The visualizations of our priority screening index that we've created using interactive maps can empower physicians and health officials to better target children at high risk for lead exposure," Distler says. "We hope our work will help lead to improved policies and actions to reach children who are most at risk for lead exposure and to improve their lives -- not just in Georgia but throughout the United States."

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From sea to shining sea: new survey reveals state-level opinions on climate change

A new report analyzing state-level opinions on climate change finds the majority of Americans believe in and want action on climate change--but factors like state politics and local climate play important roles.

RESOURCES FOR THE FUTURE (RFF)

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North and South, rural and urban--the United States is a complex mix of cultures, mindsets, and life experiences. And, as a new report by researchers at Stanford University, Resources for the Future, and ReconMR illustrates, those state-by-state differences affect climate attitudes and opinions.

The report is the latest installment of Climate Insights 2020, a seven-part series that reveals American beliefs, attitudes, and opinions on climate change and mitigation policies. The latest installment combines data from 27,661 respondents into a single dataset, then separates those data by state. Through this unique formulation, the report reveals state and regional opinions on climate change and their potential impacts on voting just days ahead of the presidential election.

As well as assessing where each state stands on a variety of climate-related issues, the report explains variation between states using indicators ranging from state-level politics to typical temperatures to residential energy prices.

Top Findings

• The majority of residents in all analyzed states hold "green" opinions--for example, more than 70% of residents in all states believe that climate change has occurred.
• At least 60% of people in all analyzed states believe that climate change will be a serious problem for the United States and world.
• The "issue public"--the people who consider climate change extremely personally important and vote based on the issue--varies from state to state. In Rhode Island, 33% of people care deeply about climate change, while in South Dakota only 9% do so.
• People in states that conferred more votes to President Trump in the 2016 election demonstrated a lower level of acceptance of the fundamentals of climate change and reduced support for specific policies to mitigate it.
• The larger the majority expressing "green" opinions on climate change, the more likely their US congressional representatives were to vote for "green" policies. The more of a state's population is passionate about the issue, the more likely representatives are to vote for those policies.

"These data provide strong signals to many policymakers about how their constituents would like them to vote on legislation related to global warming," report coauthor Jon Krosnick said. "With just over a week until the presidential election, these findings document the likely role that climate will play in voting decisions from coast to coast."

To learn more about these findings, read Climate Insights 2020: Opinion in the States by Jared McDonald, postdoctoral research fellow at Stanford University; Bo MacInnis, lecturer at Stanford University and PhD economist; and Jon Krosnick, social psychologist, professor at Stanford University, and RFF university fellow. The Climate Insights 2020 interactive data tool also allows users to explore the data in greater depth.

The final report installment in this series will be a synthesis of the six installments. Previous ones have focused on overall trends, natural disasters, climate policies, partisan breakdowns of those policies, and electric vehicles.

 Estimating risk of airborne COVID-19 with mask usage, social distancing

The Contagion Airborne Transmission inequality model illustrates correlation between physical distancing and protection, the efficacy of face masks and the impact of physical activity on transmission.

AMERICAN INSTITUTE OF PHYSICS

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IMAGE: LARGE-EDDY SIMULATION RESULTS OF THE AEROSOL "CLOUDS " GENERATED BY THE BREATHING OF AN INFECTED HOST IN A TURBULENT BOUNDARY LAYER. view more 

CREDIT: RAJAT MITTAL, CHARLES MENEVEAU AND WEN WU

WASHINGTON, October 26, 2020 -- The continued increase in COVID-19 infection around the world has led scientists from many different fields, including biomedicine, epidemiology, virology, fluid dynamics, aerosol physics, and public policy, to study the dynamics of airborne transmission.

In Physics of Fluids, by AIP Publishing, researchers from Johns Hopkins University and the University of Mississippi used a model to understand airborne transmission that is designed to be accessible to a wide range of people, including nonscientists.

Employing basic concepts of fluid dynamics and the known factors in airborne transmission of diseases, the researchers propose the Contagion Airborne Transmission (CAT) inequality model. While not all factors in the CAT inequality model may be known, it can still be used to assess relative risks, since situational risk is proportional to exposure time.

Using the model, the researchers determined protection from transmission increases with physical distancing in an approximately linear proportion.

"If you double your distance, you generally double your protection," said author Rajat Mittal. "This kind of scaling or rule can help inform policy."

The scientists also found even simple cloth masks provide significant protection and could reduce the spread of COVID-19.

"We also show that any physical activity that increases the breathing rate and volume of people will increase the risk of transmission," said Mittal. "These findings have important implications for the reopening of schools, gyms, or malls."

The CAT inequality model is inspired by the Drake equation in astrobiology and develops a similar factorization based on the idea that airborne transmission occurs if a susceptible person inhales a viral dose that exceeds the minimum infectious dose.

The model includes variables that can added at each of the three stages of airborne transmission: the generation, expulsion, and aerosolization of the virus-containing droplets from the mouth and nose of an infected host; the dispersion and transport via ambient air currents; and the inhalation of droplets or aerosols and the deposition of the virus in the respiratory mucosa in a susceptible person.

The researchers hope to look more closely at face mask efficiency and the transmission details in high-density outdoor spaces. Beyond COVID-19, this model based on the CAT inequality could apply to the airborne transmission of other respiratory infections, such as flu, tuberculosis, and measles.

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The article, "A mathematical framework for estimating risk of airborne transmission of COVID-19 with application to face mask use and social distancing," is authored by Rajat Mittal, Charles Meneveau, and Wen Wu. The article appears in Physics of Fluids and can be accessed at https://aip.scitation.org/doi/10.1063/5.0025476.

ABOUT THE JOURNAL

Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex fluids. See https://aip.scitation.org/journal/phf.