Smallest earthquakes ever detected in micron-scale metals

On the micrometer scale deformation properties of metals change profoundly: the smooth and continuous behaviour of bulk materials often becomes jerky due to random strain bursts of various sizes.

Peer-Reviewed Publication

EÖTVÖS LORÁND UNIVERSITY (ELTE), FACULTY OF SCIENCE

 

IMAGE: ON THE MICROMETER SCALE DEFORMATION PROPERTIES OF METALS CHANGE PROFOUNDLY: THE SMOOTH AND CONTINUOUS BEHAVIOUR OF BULK MATERIALS OFTEN BECOMES JERKY DUE TO RANDOM STRAIN BURSTS OF VARIOUS SIZES. view more 

CREDIT: CREDIT: PÉTER DUSÁN ISPÁNOVITY AND DÁVID UGI

On the micrometer scale deformation properties of metals change profoundly: the smooth and continuous behaviour of bulk materials often becomes jerky due to random strain bursts of various sizes. The reason for this phenomenon is the complex intermittent redistribution of lattice dislocations (which are line-like ctystal defects responsible for the irreversible deformation of crystalline materials) due to external loading, which is also the cause of the formation of the uneven step-like surface upon deformation.

To study this phenomenon in more detail, research groups of the Eötvös Loránd University of Budapest, Charles University of Prague and École des Mines de Saint-Étienne have developed a highly sensitive micromechanical platform, where weak elastic waves emitted by the specimen can be detected during the deformation of micron-scale pillars. Compression experiments performed on such zinc single crystalline micropillars in a scanning electron microscope confirmed that these so-called acoustic signals indeed occur during strain bursts, so, this experiment allowed us, for the first time, to practically hear the `sound of dislocations’.

The acoustic signals are sampled with a rate of 2.5 MHz, therefore, they provide extremely detailed information on the dynamics of dislocations. The in-depth statistical analyses performed by the researchers revealed that strain bursts exhibit a two-level structure: what has so far been seen as a single plastic slip is, in fact, a result of several correlated events on a μs-ms timescale.

The most surprising outcome of the experiments is that this process,

despite the fundamental differences between deformation mechanisms of metals and that of tectonic plates, was found to be completely analogous to earthquakes.

Acoustic signals emitted from the testpieces followed fundamental empirical laws established for main shocks and aftershocks in seismology, such as the Gutenberg-Richter and Omori laws.

 

VIDEOABSTRACT: https://youtu.be/kAf4iP8PnkU Compression of a zinc micropillar. The otherwise ultrasonic acoustic signals were transformed into the audible domain to better illustrate the correlation between acoustic events and strain bursts.

 

`These results are expected to bear high technological impact since, for the first time, we were able to observe direct connection between acoustic signals and the plastic events that emitted them’ said Péter Dusán Ispánovity, assistant professor at Eövös Loránd University and head of the Micromechanics and Multiscale Modelling Research Group. `Since the measurement of acoustic emission is a frequent method for monitoring and locating material failure in technological applications, by providing fundamentally new information about the underlying physics our results are expected to contribure to the further development of this technique.’

Dávid Ugi, PhD student in the group of Ispánovity and corresponding author of the publication added: `These experiments are rather complex, since one has to couple the nanometer precision manipulation tool with the extremely sensitive acoustic sensor, all in the vacuum chamber of a scanning electron microscope.

Such measurements, to our knowledge, at the moment can only be performed at our laboratory’ added the young researcher.

The methodology can also be used to investigate other types of deformation mechanisms, such as twinning or fracture, so the results, which were published in Nature Communications, are expected to open up new vistas in the research of micromechanical propeties of materials.

CAPTION

The reason for this phenomenon is the complex intermittent redistribution of lattice dislocations (which are line-like ctystal defects responsible for the irreversible deformation of crystalline materials) due to external loading, which is also the cause of the formation of the uneven step-like surface upon deformation.

CREDIT

Credit: Péter Dusán Ispánovity and Dávid Ugi

JOURNAL

Nature Communications

DOI

10.1038/s41467-022-29044-7 

ARTICLE TITLE

Dislocation avalanches are like earthquakes on the micron scale

ARTICLE PUBLICATION DATE

13-Apr-2022

Management researchers prescribe possible remedy in opioid misuse

Peer-Reviewed Publication

UNIVERSITY OF TEXAS AT DALLAS

 

IMAGE: DR. METIN CAKANYILDIRIM view more 

CREDIT: UT DALLAS

A decision-support framework developed by management science researchers from The University of Texas at Dallas could help clinicians objectively identify and estimate harms and benefits of opioid use for pain management.

In a study published online Feb. 3 in the INFORMS journal Decision Analysis, Naveen Jindal School of Management researchers explored how clinicians make decisions when prescribing opioids and developed a quantitative model of the process that incorporates multiple factors.

“The ongoing opioid epidemic has been a serious public health problem, and prescription opioids play a role in this problem,” said Dr. Metin Cakanyildirim, professor of operations management and one of the study’s authors. “Opioid drugs are initially prescribed to treat pain, but their use can potentially lead to adverse effects of drug tolerance, increased sensitivity to pain, dependence, addiction and overdose.”

According to the Centers for Disease Control and Prevention (CDC), more than 14,000 people died in 2019 from overdoses involving prescription opioids.

Cakanyildirim and first author Abdullah Gokcinar, a doctoral student in operations management, were motivated by the opportunity to use management science tools to manage a nonmonetary process — pain — occurring outside business contexts.

To provide an analytical framework for evidence-based opioid prescribing, they collaborated with pain researchers Dr. Ted Price BS’97, Ashbel Smith Professor of neuroscience in the School of Behavioral and Brain Sciences and director of the Center for Advanced Pain Studies, and Dr. Meredith Adams, assistant professor of anesthesiology at Wake Forest School of Medicine.

Opioid decision-making incorporates recovery time and pain intensity, as well as gender, age and drug-use history, Gokcinar said. When prescribing opioids, a clinician faces several uncertainties, including opioid tolerance and hypersensitivity.

CDC guidelines direct clinicians to prescribe the lowest effective dose of opioids. The agency emphasizes evaluation of trade-offs in opioid use and directs clinicians to assess pain, check patient opioid history, discuss adverse effects and observe patient cues for drug abuse.

Although recent guidelines loosely limit prescription amounts, the exact prescription decision is left to the clinician, who typically mentally accounts for the trade-offs of beneficial versus adverse effects.

By quantifying this mental process, the researchers built a framework that could lead to prescription decision-support tools. The framework incorporates several parameters related to pain and recovery time, as well as adverse effects such as discomfort, dependence, tolerance and hypersensitivity.

The analysis found that over- and under-prescribing occur due to clinical uncertainties and lack of estimation and evaluation methods. Accurately incorporating adverse effects into the decision-support framework yields pain-management models for chronic, acute and persistent pain types.

The models provide optimal prescriptions to minimize the total pain, discomfort and suffering, and can reduce overprescribing, Gokcinar said.

“The clinician can measure the patient’s pain, approximate its trajectory and estimate the discomfort during opioid use along with the risk of addiction or overdose,” he said. “Inputting these and other factors into a decision-support framework that balances benefits and adverse effects of opioids yields an optimal prescription.”

Additional Framework Applications

Gokcinar said that such a framework could also be adapted to host patient data, including administered dosages, and to facilitate the review of a patient’s pain treatment, transfer of information back and forth between clinicians during and after a patient handover, and benchmarking of these treatments across clinics.

The study found that clinicians who initially prescribe opioids before handing over their patients to another provider are prone to underestimating the adverse effects. A framework could draw a clinician’s attention to the adverse effects or limit their prescription until the handover, he said.

“Using this model could pave the road toward frequently prescribing reduced amounts of opioids and hence adjusting prescriptions — known as adaptive treatment — according to patient statuses,” Gokcinar said. “Without such decision support, clinicians are forced to quickly come up with good prescriptions by combining their patient observations with their experiences. This is not an easy task to perform well repetitively in stressful settings.”

For patients, having a framework in place could help them understand that reduced amounts of opioids will maintain the long-term health of their nervous system.

“That might mean suffering more today to suffer less later,” Cakanyildirim said. “Pain management can be a long-term process and requires patients to be less myopic and more forward-looking.”

Using real-life data of daily reported pain levels and opioid use from Flaredown, a mobile app that helps users track their diseases and medication, the researchers inferred the timing and severity of adverse effects. Also, using data from surgery patients in a clinical setting, the researchers compared the suggestions of their models to clinical practice.

Once the models are validated in a clinical setting, they could potentially support balanced opioid prescribing. They also could aid policymakers in evaluating prescription policies.

Cakanyildirim said the researchers plan to further their work by collaborating with medical professionals and pain clinics to study information conveyed by patient questionnaires, assessments via telemedicine and adaptive treatment approaches.

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JOURNAL

Decision Analysis

DOI

10.1287/deca.2021.0447 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Balanced Opioid Prescribing via a Clinical Trade-Off: Pain Relief vs. Adverse Effects of Discomfort, Dependence, and Tolerance/Hypersensitivity

New research sheds fresh light on the ‘800-pound gorilla’ of presenteeism

Employees only engage in presenteeism, working when sick, when they have not met their daily work goals

Peer-Reviewed Publication

TRINITY COLLEGE DUBLIN

Employees who are unwell only engage in presenteeism when they have not met their daily work goals, according to new research from Trinity College Dublin.

The study, published in the Journal of Occupational Health Psychology recently, also found that working on a day when you feel ill drains mental energy which cannot be recovered the next day.

The study seeks to shed further light on the phenomenon of ‘presenteeism’ — defined by the researchers as continuing to work when experiencing ill-health. The practice has been labelled an ‘800-pound gorilla’ by researchers in occupational health psychology because of the tremendous costs it inflicts on employees and organisations alike. These costs include burnout, impaired workability, and productivity loss.

This study led by Dr Wladislaw Rivkin, Associate Professor in Organisational Behaviour, Trinity, deepens our understanding of the harmful impact of presenteeism on employee effectiveness by demonstrating that depletion of mental resources is a key mechanism responsible for these harmful effects.

The research involved 126 employees logging their daily productivity across 12 workdays, resulting in 995 daily work observations. It was conducted during the COVID-19 lockdown in 2020 when all participants were working from home.

Dr Rivkin commented:

It is crucial to tackle daily presenteeism, especially for remote workers. Managers should openly discourage presenteeism by reassuring team members that if they feel unwell it is acceptable to reduce their daily work goals and instead tend to their health. In light of the energy-depleting nature of presenteeism if employees engage in presenteeism they should work on tasks that are inherently pleasant rather than tedious tasks that further drain their energy.

So, while it may seem a good idea to work despite ill health to deliver on work goals our research shows that this has a knock-on effect for remote workers’ performance on the next day as presenteeism drains employees’ psychological energy, which cannot be fully recovered after work.

The full paper was entitled ‘Should I stay or should I go? The role of daily presenteeism as an adaptive response to perform at work despite somatic complaints for employee effectiveness’.

Wlad Rivkin is an Associate Professor in Organisational Behaviour and Work Psychology whose research focuses on burnout, stress and other demands that people experience at work as well as what organisations can do to protect employee wellbeing and maintain their effectiveness. Other recent research projects include studies on the impact of commuting on employee wellbeing, the role of willpower in overcoming the negative effects of a bad night’s sleep and how smartphone use during non-work time impacts on sleep quality.

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DOI

10.1037/ocp0000322 

METHOD OF RESEARCH

Case study

ARTICLE TITLE

Should I stay or should I go? The role of daily presenteeism as an adaptive response to perform at work despite somatic complaints for employee effectiveness.

Research reveals human-driven changes to distinctive foraging patterns in North Pacific Ocean

The first large-scale study of its kind has uncovered more than 4,000 years’ worth of distinctive foraging behaviour in a species once driven to the brink of extinction.

Peer-Reviewed Publication

UNIVERSITY OF LEICESTER

 

IMAGE: THIS MAP SHOWS KNOWN BREEDING ISLANDS ALONGSIDE THE ARCHAEOLOGICAL AND HISTORICAL SAMPLING SITES IN THE CONTEXT OF THE NORTH PACIFIC OCEAN AND THE SHORT-TAILED ALBATROSS’ FORAGING RANGE. RANGE DATA FROM BIRDLIFE INTERNATIONAL. CREDIT: ERIC GUIRY/UNIVERSITY OF LEICESTER view more 

CREDIT: ERIC GUIRY/UNIVERSITY OF LEICESTER

The first large-scale study of its kind has uncovered more than 4,000 years’ worth of distinctive foraging behaviour in a species once driven to the brink of extinction.

An international team of researchers, led by the University of Leicester, identified long-term patterns in the behaviour of the short-tailed albatross (Phoebastria albatrus) in the North Pacific Ocean by studying isotopes found in archaeological and museum-archived samples of the bird, dating as far back as 2300 BCE.

Their findings, published today (Thursday) in Communications Biology, show long-term patterns in foraging behaviour for the short-tailed albatross for the first time – and demonstrate how individual birds foraged the same hyper-localised sites for thousands of years in spite of the species’ huge potential foraging range across thousands of miles of Pacific coastline and open ocean.

But this behaviour, a demonstration of long-term individual foraging site fidelity (LT-IFSF), can pose significant risks for animals who specialise in areas which may be impacted by human activity.

The short-tailed albatross was brought to the brink of extinction by feather hunters between the 1880s and 1930s and though careful conservation has resulted in exponential population growth in recent decades, this trend of LT-IFSF has not been observed in the last century.

Dr Eric Guiry is Lecturer in Biomolecular Archaeology at the University of Leicester and corresponding author for the study, which focused on two locations close to Yuquot, Canada, and compared findings to sites in the USA, Russia and Japan. He said:

“Understanding migratory behaviour is critical for global biodiversity restoration because it helps identify vulnerable regions for environmental protection.

“Although evidence for the extent and depth of LT-IFSF across other species is still emerging, the extreme distances and time scale of the behaviour seen here indicates that this foraging strategy may be a fundamental, density-driven adaptation that could become widespread again as recovering animal populations reach pre-industrial levels.”

The research team from Leicester, the Land of Maquinna Cultural Society (Canada), Vrije Universiteit Brussel (Belgium) and Simon Fraser University (Canada) were able to track this foraging behaviour by examining stable carbon and nitrogen isotope compositions in samples of bone collagen.

In contrast to most other tissues such as muscle or feather, which turn over on a scale of days, weeks, or months), isotopic compositions from bone collagen, which remodels slowly over the entire lifespan on an individual, reflect an average of foods consumed over the last several years of an individual’s life.

This provides a unique perspective for exploring lifetime trends in animal diet and migration behaviour.

By mapping these biological markers against known isotopic baselines across the species’ foraging range, linked to factors such as sea surface temperature and CO2 concentrations, the researchers were able to build up a picture of the short-tailed albatross’ migratory and foraging behaviour over hundreds of generations.

But, crucially, as this behaviour is no longer observed among these birds, their findings show this hyper-specialised foraging in specific locations disappeared after the birds were hunted to near extinction in the 1880s, when only a handful of birds remained. Dr Guiry continued:

“We think this behaviour could be driven by competition among birds, meaning that, as the population recovers, we could see it re-emerge. This kind information is important because it provides advanced warning that monitoring for this remarkable behaviour, which can make the birds more vulnerable to human impacts, may need close attention.

“One of the most exciting findings, however, is actually quite a positive note. Our data also indicate that Indigenous communities at Yuquot were harvesting these birds with little impact on their population for thousands of years.

“Not only does this tell us something about the long-term sustainability of Indigenous marine resource use at Yuquot, it provides a clear example of how people and the short-tailed albatross can co-exist.”

‘Four millennia of long-term individual foraging site fidelity in a highly migratory marine predator’ is published in Communications Biology.

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JOURNAL

Communications Biology

DOI

10.1038/s42003-022-03310-2 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animal tissue samples

ARTICLE TITLE

Four millennia of long-term individual foraging site fidelity in a highly migratory marine predator

ARTICLE PUBLICATION DATE

14-Apr-2022

Photocatalysts with built-in electric field helps to remove pollutants from water

Peer-Reviewed Publication

HEFEI INSTITUTES OF PHYSICAL SCIENCE, CHINESE ACADEMY OF SCIENCES

 

IMAGE: FIGURE 1. THE PREPARED CDTEQDS/2DBWO PHOTOCATALYST WITH DIFFERENT PROPORTIONS. view more 

CREDIT: YANG PENGQI

A team led by Prof. WU Zhengyan from Institute of Intelligent Machines, Hefei Institutes of Physical Science recently introduced a high-efficiency Z-scheme photocatalyst to deal with contaminants in water.

This new solution has been published in ACS Applied Nano Materials.

In recent years, the rapid industrialisation has caused increasingly severe environmental pollution. Therein, kinds of organic pollutants in water have become major threats for human health and the ecosystem security worldwide. Therefore, an effective treatment approach has become an urgent task for elimination of organic pollutants at present.

In this research, the Bi2WO6(CdTeQDs/2DBWO) photocatalyst with a giant built-in electric field (BEF) was proved to extremely promote the dissociation of exciton and generation of reactive oxygen species. Scientists demonstrated BEF played a positive role during photocatalytic process, which exhibited much higher photodegradation efficiency for phenol, rhodamine B, and tetracycline compared to the pure Bi2WO6 under the visible light.

Compared to the commercial TiO2 photocatalyst, self-prepared CdTeQDs/2DBWO photocatalyst exhibited a slight advantage in photocatalytic efficiency for contaminants. However, due to a complicated synthesis process and a high cost, self-prepared photocatalyst is difficult to be applied in practical application, at present.

This study opened up a new route to design a high-efficiency photocatalysts.

CAPTION

Figure 2. Schematic illustration of photocatalytic degradation mechanism.

CREDIT

YANG Pengqi

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JOURNAL

ACS Applied Nano Materials

DOI

10.1021/acsanm.2c00155 

ARTICLE TITLE

CdTe Quantum Dot/Bi2WO6 Nanosheet Photocatalysts with a Giant Built-In Electric Field for Enhanced Removal of Persistent Organic Pollutants

ARTICLE PUBLICATION DATE

8-Apr-2022

Missing-link black hole found lurking in plain sight

Peer-Reviewed Publication

NATIONAL INSTITUTES OF NATURAL SCIENCES

 

IMAGE: ARTISTIC IMPRESSION OF A YOUNG GROWING BLACK HOLE EMERGING FROM THE CENTER OF A DUSTY STARBURST GALAXY. view more 

CREDIT: ESA/HUBBLE N. BARTMANN

An international research team has discovered a supermassive black hole in the early Universe that could provide the missing link in the evolution of quasars, some of the brightest objects in space. This new object was discovered in the most unlikely place: already archived observations of one of the most intensively studied regions of the sky. This result is important for understanding the evolution of supermassive black holes, like the one hiding at the center of our own Milky Way Galaxy. And the method of discovery suggests that there are more surprises waiting to be discovered in the archive data.

Quasars, extremely bright objects powered by matter falling into a supermassive black hole, formed early in the history of the Universe, only 700-800 million years after the Big Bang. It is believed that quasars evolved from supermassive black holes in dusty starburst galaxies, a class of galaxies that has also been confirmed to have appeared early on. But there has been no direct evidence linking the two.

Researchers found evidence for the missing link while analyzing archived Hubble Space Telescope data for a region of the sky known as the “Hubble GOODS North field” in the constellation Ursa Major. This field has been studied extensively by Hubble and other world-leading telescopes. The team noticed an object, nicknamed GNz7q, that appears to be a black hole just starting to overpower its host galaxy in the process of becoming a quasar. Additional archive data including the Subaru Telescope, which can see farther into infrared wavelengths than Hubble, allowed astronomers to distinguish the black hole from its host galaxy.

Seiji Fujimoto, lead author of the paper describing the discovery, explains his vision for future research, “Subaru Telescope’s Hyper Suprime-Cam has also discovered a large number of quasars in the early universe, and further observations with the ALMA radio telescope and the James Webb [Space Telescope] have been scheduled. Detailed analysis at multiple wavelengths with a combination of these telescopes may find even more objects like GNz7q in the future.”

These results appeared as Fujimoto et al. “A dusty compact object bridging galaxies and quasars at cosmic dawn” in Nature on April 13, 2022.

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JOURNAL

Nature

DOI

10.1038/s41586-022-04454-1 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

A dusty compact object bridging galaxies and quasars at cosmic dawn

ARTICLE PUBLICATION DATE

13-Apr-2022

New report: Total economic burden of MS in United States is more than $85 billion

Peer-Reviewed Publication

AMERICAN ACADEMY OF NEUROLOGY

MINNEAPOLIS –  The estimated cost of multiple sclerosis (MS) reached $85.4 billion in 2019 in the United States, according to a new report published in the April 13, 2022, online issue of Neurology®, the medical journal of the American Academy of Neurology. In addition, when researchers compared people with MS to people without MS they found that excess medical costs represent 74% of the overall economic burden of MS. The excess medical cost per person was $65,612 that year.

These costs not only reflect the cost of medications and health care. Neurologic disability can prevent people with MS from working or limit employment opportunities and reduce earnings. Also, many family members need to leave their employment to be caregivers. These costs are also reflected in this analysis as non-medical costs.

“Multiple sclerosis is an expensive disease to treat and the debilitating effects of MS can result in considerable disruption to daily living including work, physical independence, mobility and social interaction,” said study author Bruce Bebo, PhD, of the National Multiple Sclerosis Society in New York, NY. “The findings of this study help underscore the burden of MS in the US and our hope is our results will inform decision-making regarding MS-related health resources.”

Multiple sclerosis is a disease of the central nervous system which is made up of the brain, spinal cord and optic nerves. MS is chronic and can be unpredictable and disabling. Symptoms may include fatigue, numbness and tingling, loss of balance, weakness and problems with vision. An estimated 1 million people in the United States live with MS, and it affects more women than men. While there are medications to treat symptoms of the disease, there is currently no cure for MS.

For the study, researchers reviewed Medicare and insurance claims to determine direct medical costs, looking at a total of 10,589 people with MS and another 105,893 people without MS matched for age and sex. They calculated the per person direct medical costs for 2017, 2018 and 2019, and then calculated the average one-year cost. Researchers also surveyed 946 study participants and their caregivers about indirect costs, such as job loss or lost productivity on the job, cost of paid and unpaid caregivers, and home modifications.

Researchers found an estimated total economic burden in the U.S. of $85.4 billion. That amount included $63.3 billion in direct medical costs as well as $22.1 billion in indirect non-medical costs. Prescription medications were the largest component with $37.9 billion, amounting to about 54% of direct medical costs, followed by drugs administered in the clinic with $6.7 billion or about 12%, and outpatient care with $5.5 billion or 9%.

The average excess medical costs for a person with MS compared to a person without MS was $65,612. That included $35,154 for medication, the largest proportion of this cost.

The annual cost for a person taking MS medications ranged from $57,202 to $92,719.

“The costs of MS are very high not only on a personal level but a national level as well,” Bebo said. “Our results suggested a possible role for additional policy initiatives to better support individuals and families affected, in terms of providing treatment and long-term care, work-site support, employment, and occupational training. These measures could reduce the economic burden of MS and help improve the lives of those living with MS and their family caregivers.”

Bebo added, “Right now, in the U.S. there are about one million adults with MS and we estimated that by 2039, there will be nearly 1.2 million people living with MS. With this, the economic burden will increase to $108.1 billion."

A limitation of this study was that the indirect and non-medical costs were estimated using a self-administered survey and relied on respondents’ memory, meaning some costs may have not been accurately reported.

The study was commissioned and paid for by the National Multiple Sclerosis Society.

Learn more about multiple sclerosis at BrainandLife.org, home of the American Academy of Neurology’s free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life® on Facebook, Twitter and Instagram.

When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.

The American Academy of Neurology is the world’s largest association of neurologists and neuroscience professionals, with over 38,000 members. The AAN is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer’s disease, stroke, migraine, multiple sclerosis, concussion, Parkinson’s disease and epilepsy.

For more information about the American Academy of Neurology, visit AAN.com or find us on Facebook, Twitter, Instagram, LinkedIn and YouTube.

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JOURNAL

Neurology

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE PUBLICATION DATE

13-Apr-2022

Bisphenol A (BPA) impacted rat offspring more seriously than their dams

Peer-Reviewed Publication

EHIME UNIVERSITY

 

IMAGE: SUPERSCRIPT CAPITAL LETTERS INDICATE WHICH OMICS DATA SUPPORTS THE IMPACT OF BPA: T: TRANSCRIPTOMICS, P: PROTEOMICS, L: LIPIDOMICS, M: MULTI-OMICS ANALYSIS view more 

CREDIT: ©ECOTOXICOLOGY LABORATORY, CENTER FOR MARINE ENVIRONMENTAL STUDIES (CMES), EHIME UNIVERSITY

Bisphenol A (BPA) is an anthropogenic chemical used as a raw material for plastics such as polycarbonate and epoxy resins, and for the inner coating of canned foods. BPA has been detected in human specimens, including fetuses. In addition, BPA contaminates soil, water, air, and wildlife.

The ecotoxicology research group at the Center for Marine Environmental Studies (CMES) of Ehime University, Japan administered 0, 50, and 5000 μg/kg body weight/day of BPA to pregnant rats to investigate the effects of prenatal BPA exposure on the liver transcriptome, proteome, and lipidome of the neonates (Nguyen et al., 2020, 2021). The results showed that prenatal BPA exposure affects lipid and hormone homeostasis in neonates in a sex- and growth-dependent manner. BPA exposure also affected the expression levels of cell cycle- and insulin resistance-related genes in offspring, and females showed a decrease in the hepatic lipid content and an increase in  body weight. However, the effects of BPA on rat dams had not yet been explored.

In this study, to investigate the effects of BPA exposure during pregnancy on rat dams, the CMES group examined changes in the transcriptome and lipidome of the liver of mother rats on postnatal day 23 (after weaning of the newborns). In addition, the effects were compared with those of their offspring. The CMES group also performed multivariate analyses (DIABLO: Data Integration Analysis for Biomarker discovery using Latent cOmponents) to integrate the hepatic transcriptome and lipidome data and attempted to comprehensively understand the effects of BPA exposure.

The effects of BPA exposure during pregnancy on dams were compared to the effects on offspring exposed during the fetal period. The results showed that even 4 weeks after exposure, maternal rats showed effects on insulin signaling, circadian rhythm, and immune response at the transcriptome level. On the other hand, no effects on the lipid composition or body weight of the dams were observed, indicating that the effects on the mother rats were slight compared to those of the offspring. These results suggest that BPA exposure in utero poses a higher risk than exposure in adulthood.

DIABLO successfully discriminated the BPA exposure groups of dams and their offspring based on differences in the effects of the hepatic transcriptome and lipidome. The discrimination accuracy between the 5000 μg BPA/kg body weight/day exposure group and the control group was higher than that between the 50 μg BPA/kg body weight/day exposure group and the control group, suggesting a dose-dependent effect of BPA. In addition, genes and lipids associated with BPA exposure were predicted, and palmitic acid and genes related to circadian rhythm, insulin response, and lipid metabolism were identified as novel biomarker candidates of BPA effects across two generations of mothers and offspring. This is the first report to integrate multi-omics data using the multivariate analysis tool, DIABLO, to comprehensively understand the effects of BPA exposure during pregnancy on mother rats and their offspring.

This study was published in Science of the Total Environment on February 19, 2022.

 

References

Nguyen, H.T., Yamamoto, K., Iida, M., Agusa, T., Ochiai, M., Guo, J., Karthikraj, R., Kannan, K., Kim, E.-Y., Iwata, H., 2020. Effects of prenatal bisphenol A exposure on the hepatic transcriptome and proteome in rat offspring. Sci. Total Environ. 720, 137568. https://doi.org/10.1016/j.scitotenv.2020.137568.

Nguyen, H.T., Li, L., Eguchi, A., Kannan, K., Kim, E.-Y., Iwata, H., 2021. Effects on the liver lipidome of rat offspring prenatally exposed to bisphenol A. Sci. Total Environ. 759, 143466. https://doi.org/10.1016/j.scitotenv.2020.143466.

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JOURNAL

Science of The Total Environment

DOI

10.1016/j.scitotenv.2022.153990 

ARTICLE TITLE

Bisphenol A (BPA) impacted rat offspring more seriously than their dams