Sunday, September 24, 2023

Research estimates that a mere 2% of all chemical exposure has been identified

What chemicals are we exposed to on a daily basis? That is the central question of "non-targeted analysis" or NTA, an emerging field of analytical science that aims to identify all chemicals around us. A daunting task, because how can you be sure to detect everything if you don't know exactly what you're looking for?

In a paper published in Environmental Science and Technology, researchers at the Universities of Amsterdam (UvA, the Netherlands) and Queensland (UQ, Australia) have assessed this problem. In a meta-analysis of NTA results published over the past six years, they estimate that less than 2% of all chemicals have been identified.

According to Viktoriia Turkina who performed the research as a Ph.D. student with Dr. Saer Samanipour at the UvA's Van 't Hoff Institute for Molecular Sciences, this limitation underscores the urgent need for a more proactive approach to chemical monitoring and management. "We need to incorporate more data-driven strategies into our studies to be able to effectively protect the human and environmental health," she says.

Samanipour explains that current monitoring of chemicals is rather limited since it's expensive, time consuming, and requires specialized experts. "As an example, in the Netherlands we have one of the most sophisticated monitoring programs for chemicals known to be of concern to human health. Yet we target less than 1,000 chemicals. There are far more chemicals out there that we don't know about."

A vast chemical space

To deal with those chemicals, some 15 to 20 years ago the concept of non-targeted analysis was introduced to look at possible exposure in an unbiased manner. The idea is to take a sample from the environment (air, water, soil, sewer sludge) or the human body (hair, blood, etc.) and analyze it using well-established techniques such as chromatography coupled with high resolution mass spectroscopy.

The challenge then is to trace the obtained signal back to the structures of chemicals that may be present in the sample. This will include already known chemicals, but also chemicals of which the potential presence in the environment is yet unknown.

In theory, this "chemical space" includes as many as 1060 compounds, an incomprehensible number that exceeds the number of stars in the universe by far. On the other hand, the number of organic and inorganic substances published in the scientific literature and public databases is estimated at around 180 million.

To make their research more manageable, Turkina, Samanipour and co-workers focused on a subset of 60,000 well-described compounds from the NORMAN database. Turkina says, "This served as the reference to establish what is covered in NTA studies, and more importantly, to develop an idea about what is being overlooked."

The vast 'exposome' of chemicals that humans are exposed to on a daily basis is a sign of our times, according to Samanipour.

"These days we are soaking in a giant ocean of chemicals. The chemical industry is part of that, but also nature is running all a whole bunch of reactions that result in exposure. And we expose ourselves to chemicals by the stuff we use—think for instance of the problem of microplastics. To solve all this we have to be able to go beyond pointing fingers. With our research, we hope to contribute to finding a solution together. Because we all are in the same boat."

Much room for improvement

The meta analysis, which included 57 NTA papers, revealed that only around 2% of the estimated chemical space was covered. This can indicate that the actual exposure to chemicals is indeed quite low, however, it can also point to shortcomings in the applied analyses. According to Turkina and Samanipour, the latter is indeed the case. They focused on NTA studies applying liquid chromatography coupled with high resolution mass spectrometry (LC-HRMS) -one of the most comprehensive methods for the analysis of complex environmental and biological samples.

It turned out that there was much room for improvement. For instance in sample preparation, they observed a bias towards specific compounds rather than capturing a more diverse set of chemicals. They also observed poor selection and inconsistent reporting of LC-HRMS parameters and data acquisition methods.

"In general," Samanipour says, "the chemical analysis community is to a great extent driven by the available technology that vendors have developed for specific analysis purposes. Thus the instrumental set-up and data processing methods are rather limited when it comes to non-targeted analysis."

To Samanipour, the NTA approach is definitely worth pursuing. "But we need to develop it further and push it forward. Together with vendors we can develop new powerful and more versatile analytical technologies, as well as effective data analysis protocols."

He also advocates a data-driven approach were the theoretical chemical space is "back calculated" towards a subset of chemicals that are highly likely to be present in our environment. "Basically we have to better understand what is the true chemical space of exposure. And once those boundaries are defined, then it becomes a lot easier to assess that number of 2% we have determined."

More information: Tobias Hulleman et al, Critical Assessment of the Chemical Space Covered by LC–HRMS Non-Targeted Analysis, Environmental Science & Technology (2023). DOI: 10.1021/acs.est.3c03606

Journal information: Environmental Science and Technology , Environmental Science & Technology

Provided by University of Amsterdam Using machine learning to improve the toxicity assessment of chemicals

Research presents new development model for the world's third-longest river

by University of North Carolina at Chapel Hill

A new research paper published in Science Advances reveals how changes in the size of the Yangtze River watershed may have led to the carving of deep canyons

In this study, UNC-Chapel Hill professor Eric Kirby and his co-authors explore the impact of drainage basin expansion on the growth of the Yangtze River.

"This study presents a new model for when and how the Yangtze River was born," said Kirby, "The Yangtze is one of the world's great rivers, rising on the Tibetan Plateau at altitudes over 17,000 feet and descending through some of the deepest canyons on the planet toward the East China Sea. The timing of when these canyons were carved is commonly attributed to the uplift of the Tibetan Plateau, but whether the rivers existed in their present-day configuration has been uncertain."

Landscape evolution simulations demonstrated that expansion of the Yangtze watershed since the Late Miocene could be responsible for 1 to 2 kilometers of fluvial incision. In addition, increased erosive power associated with capture and basin integration drove accelerated incision during the Late Miocene.

"One key observation is that ancient lakes were present on the top of the plateau. Our work shows that the effect of capturing these lake basins can explain much of the timing of river incision and the depth of those canyons. Essentially, the Yangtze used to be a shorter, smaller river," Kirby adds.

The study also implies that eastern Tibet was elevated prior to approximately 15 million years ago and the timing of fluvial incision may be out of phase with the growth of plateau topography.

Research presents new development model for the world's third-longest river — *Overview of eastern Tibet with major river catchments and distribution of Miocene lake*

More information: Alexander Rohrmann et al, Accelerated Miocene incision along the Yangtze River driven by headward drainage basin expansion, Science Advances (2023). DOI: 10.1126/sciadv.adh1636

Journal information: Science Advances

Provided by University of North Carolina at Chapel Hill Researchers home in on the age of the Yangtze River

Negative 'retweets' appear to add to voter fraud conspiracy theories

by Stony Brook University

A team of behavioral scientists using big data and a simulation-based model to analyze social media "tweets" around the 2020 presidential election found that the spread of voter fraud conspiracy theories on Twitter (now called X) was boosted by a negativity bias. Led by Mason Youngblood, Ph.D., a post-doctoral fellow in the Institute for Advanced Computational Science at Stony Brook University, the findings are published in Humanities and Social Sciences Communications.

The researchers simulated the behavior of around 350,000 real Twitter users. They found that the sharing patterns of some 4 million tweets about voter fraud are consistent with people being much more likely to retweet social posts that contain stronger negative emotion.

The data for their study came from the VoterFraud2020 dataset, collected between October 23 and December 16, 2020. This dataset includes 7.6 million tweets and 25.6 million retweets that were collected in real-time using X's streaming Application Program Interface, under the established guidelines for ethical and social media data use.

"Conspiracy theories about large-scale voter fraud spread widely and rapidly on Twitter during the 2020 U.S. presidential election, but it is unclear what processes are responsible for their amplification," says Youngblood.

Given that, the team ran simulations of individual users tweeting and retweeting one another under different levels and forms of cognitive bias and compared the output to real patterns of retweet behavior among proponents of voter fraud conspiracy theories during and around the election.

"Our results suggest that the spread of voter fraud messages on Twitter was driven by a bias for tweets with more negative emotion, and this has important implications for current debates on how to counter the spread of conspiracy theories and misinformation on social media," Youngblood adds.

Through their simulations and numerical analysis, Youngblood and colleagues found that their results are consistent with previous research by others suggesting that emotionally negative content has an advantage on social media across a variety of domains, including news coverage and political discourse.

The model also showed that even though negative tweets were more likely to be retweeted, quote tweets tended to be more moderate than the original ones, as people tended not to amplify negativity when commenting on something.

Youngblood says that because the team's simulation-based model recreates the patterns in the actual data quite well, it may potentially be useful for simulating interventions against misinformation in the future. For example, the model could be easily modified to reflect the ways that social media companies or policy makers might try to curb the spread of information, such as reducing the rate at which tweets hit people's timelines.

More information: Mason Youngblood et al, Negativity bias in the spread of voter fraud conspiracy theory tweets during the 2020 US election, Humanities and Social Sciences Communications (2023). DOI: 10.1057/s41599-023-02106-x

Provided by Stony Brook University

Twitter's role in combating vaccine misinformation: New study highlights importance of influential users

Surgeons perform second pig heart transplant, trying to save a dying man

by Lauran Neergaard

Surgeons have transplanted a pig's heart into a dying man in a bid to prolong his life—only the second patient to ever undergo such an experimental feat. Two days later, the man was cracking jokes and able to sit in a chair, Maryland doctors said Friday.

The 58-year-old Navy veteran was facing near-certain death from heart failure but other health problems meant he wasn't eligible for a traditional heart transplant, according to doctors at University of Maryland Medicine.

"Nobody knows from this point forward. At least now I have hope and I have a chance," Lawrence Faucette, from Frederick, Maryland, said in a video recorded by the hospital before Wednesday's operation. "I will fight tooth and nail for every breath I can take."

While the next few weeks will be critical, doctors were thrilled at Faucette's early response to the pig organ.

"You know, I just keep shaking my head—how am I talking to someone who has a pig heart?" Dr. Bartley Griffith, who performed the transplant, told The Associated Press. He said doctors are feeling "a great privilege but, you know, a lot of pressure."

The same Maryland team last year performed the world's first transplant of a genetically modified pig heart into another dying man, David Bennett, who survived just two months.

There's a huge shortage of human organs donated for transplant. Last year, there were just over 4,100 heart transplants in the U.S., a record number but the supply is so tight that only patients with the best chance of long-term survival get offered one.

Attempts at animal-to-human organ transplants have failed for decades, as people's immune systems immediately destroyed the foreign tissue. Now scientists are trying again using pigs genetically modified to make their organs more humanlike.

Recently, scientists at other hospitals have tested pig kidneys and hearts in donated human bodies, hoping to learn enough to begin formal studies of what are called xenotransplants.

To make this new attempt in a living patient outside of a rigorous trial, the Maryland researchers required special permission from the Food and Drug Administration, under a process reserved for certain emergency cases with no other options.

It took over 300 pages of documents filed with FDA, but the Maryland researchers made their case that they'd learned enough from their first attempt last year—even though that patient died for reasons that aren't fully understood—that it made sense to try again.

And Faucette, who retired as a lab technician at the National Institutes of Health, had to agree that he understood the procedure's risks.

In a statement his wife, Ann Faucette, said, "We have no expectations other than hoping for more time together. That could be as simple as sitting on the front porch and having coffee together."

What's different this time: Only after last year's transplant did scientists discover signs of a pig virus lurking inside the heart—and they now have better tests to look for hidden viruses. They also made some medication changes.

Possibly more important, while Faucette has end-stage heart failure and was out of other options, he wasn't as near death as the prior patient.

By Friday, his new heart was functioning well without any supportive machinery, the hospital said.

"It's just an amazing feeling to see this pig heart work in a human," said Dr. Muhammad Mohiuddin, the Maryland team's xenotransplantation expert. But, he cautioned, "we don't want to predict anything. We will take every day as a victory and move forward."

This kind of single-patient "compassionate use" can provide some information about how the pig organ works but not nearly as much as more formal testing, said Karen Maschke, a research scholar at the Hastings Center who is helping develop ethics and policy recommendations for xenotransplant clinical trials. That FDA allowed this second case "suggests that the agency is not ready to permit a pig heart clinical trial to start," Mashke added.

The pig heart, provided by Blacksburg, Virginia-based Revivicor, has 10 genetic modifications—knocking out some pig genes and adding some human ones to make it more acceptable to the human immune system.

Pig heart recipient continues to recover from transplant

Astronomers find abundance of Milky Way–like galaxies in early universe, rewriting cosmic evolution theories

by Jessica Marsh, University of Manchester

Galaxies from the early universe are more like our own Milky Way than previously thought, flipping the entire narrative of how scientists think about structure formation in the universe, according to new research published today.

Using the James Webb Space Telescope (JWST), an international team of researchers including those at The University of Manchester and University of Victoria in Canada discovered that galaxies like our own Milky Way dominate throughout the universe and are surprisingly common.

These galaxies go far back in the universe's history with many of these galaxies forming 10 billion years ago or longer.

The Milky Way is a typical disk galaxy, which has a shape similar to a pancake or compact disk, rotating about its center and often containing spiral arms. These galaxies are thought to be the most common in the nearby universe and might be the types of galaxies where life can develop given the nature of their formation history.

However, astronomers previously considered that these types of galaxies were too fragile to exist in the early universe when galaxy mergers were more common, destroying what we thought was their delicate shapes.

The new discovery, published today in The Astrophysical Journal, finds that these disk galaxies are 10 times more common than what astronomers believed based on previous observations with the Hubble Space Telescope.

Christopher Conselice, professor of extragalactic astronomy at The University of Manchester, said, "Using the Hubble Space Telescope we thought that disk galaxies were almost non-existent until the universe was about 6 billion years old, these new JWST results push the time these Milky Way–like galaxies form to almost the beginning of the universe."

The research completely overturns the existing understanding of how scientists think our universe evolves, and the scientists say new ideas need to be considered.

Lead author, Leonardo Ferreira from the University of Victoria, said, "For over 30 years it was thought that these disk galaxies were rare in the early universe due to the common violent encounters that galaxies undergo. The fact that JWST finds so many is another sign of the power of this instrument and that the structures of galaxies form earlier in the universe, much earlier in fact, than anyone had anticipated."

It was once thought that disk galaxies such as the Milky Way were relatively rare through cosmic history, and that they only formed after the universe was already middle aged.

Previously, astronomers using the Hubble Space Telescope believed that galaxies had mostly irregular and peculiar structures that resemble mergers. However, the superior abilities of JWST now allows us to see the true structure of these galaxies for the first time.

The researchers say that this is yet another sign that "structure" in the universe forms much quicker than anyone had anticipated.

Professor Conselice continues, "These JWST results show that disk galaxies like our own Milky Way, are the most common type of galaxy in the universe. This implies that most stars exist and form within these galaxies which is changing our complete understanding of how galaxy formation occurs. These results also suggest important questions about dark matter in the early universe which we know very little about."

"Based on our results astronomers must rethink our understanding of the formation of the first galaxies and how galaxy evolution occurred over the past 10 billion years."

More information: Leonardo Ferreira et al, The JWST Hubble Sequence: The Rest-frame Optical Evolution of Galaxy Structure at 1.5 < z < 6.5, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/acec76

Journal information: Astrophysical Journal

Provided by University of Manchester The Milky Way's disk is warped. Is that because its dark matter halo is tilted?

Jellyfish shown to learn from past experience for the first time

by University of Copenhagen

Jellyfish are smarter than you think — A Caribbean box jellyfish. Black dots embedded low on the bell are the animal’s visual

Jellyfish are more advanced than once thought. A new study from the University of Copenhagen has demonstrated that Caribbean box jellyfish can learn at a much more complex level than ever imagined—despite only having one thousand nerve cells and no centralized brain. The finding changes our fundamental understanding of the brain and could enlighten us about our own mysterious brains.

After more than 500 million years on Earth, the immense evolutionary success of jellyfish is undeniable. Still, we've always thought of them as simple creatures with very limited learning abilities.

The prevailing opinion is that more advanced nervous systems equate with more advanced learning potential in animals. Jellyfish and their relatives, collectively known as cnidarians, are considered to be the earliest living animals to develop nervous systems and to have fairly simple nervous systems and no centralized brain.

For more than a decade, neurobiologist Anders Garm has been researching box jellyfish, a group of jellyfish commonly known for being among the world's most poisonous creatures. But these lethal jellies are interesting for another reason as well: it turns out that they are not quite as simple as once believed. And this shakes our entire understanding of what simple nervous systems are capable of.

"It was once presumed that jellyfish can only manage the simplest forms of learning, including habituation—i.e., the ability to get used to a certain stimulation, such as a constant sound or constant touch. Now, we see that jellyfish have a much more refined ability to learn, and that they can actually learn from their mistakes. And in doing so, modify their behavior," says Anders Garm, an associate professor at the University of Copenhagen's Department of Biology.

One of the most advanced attributes of a nervous system is the ability to change behavior as a result of experience—to remember and learn. The research team, headed by Jan Bielecki of Kiel University and Anders Garm, set out to test this ability in box jellyfish. The findings have just been published in the journal Current Biology.

A thousand nerve cells are more capable than once thought

The scientists studied the Caribbean box jellyfish, Tripedalia cystophora, a fingernail-sized medusa that lives in Caribbean mangrove swamps. Here, they use their impressive visual system including 24 eyes to hunt for tiny copepods among mangrove roots. While making for a good hunting grounds, the web of roots is also a dangerous place for soft-bodied jellies.

So, as the small box jellyfish approach the mangrove roots, they turn and swim away. Should they veer too soon, they won't have enough time to catch any copepods. But if they turn too late, they risk bumping into the root and damaging their gelatinous bodies. Thus, assessing distances is crucial for them. And here, contrast is the key, as the researchers discovered:

"Our experiments show that contrast, i.e., how dark the root is in relation to the water, is used by the jellyfish to assess distances to roots, which allows them to swim away at just the right moment. Even more interesting is that the relationship between distance and contrast changes on a daily basis due to rainwater, algae and wave action," says Anders Garm.

"We can see that as each new day of hunting begins, box jellyfish learn from the current contrasts by combining visual impressions and sensations during evasive maneuvers that fail. So, despite having a mere one thousand nerve cells—our brains have roughly 100 billion—they can connect temporal convergences of various impressions and learn a connection—or what we call associative learning. And they actually learn about as quickly as advanced animals like fruit flies and mice."

Credit: University of Copenhagen

The new research results break with previous scientific perceptions of what animals with simple nervous systems are capable of:

"For fundamental neuroscience, this is pretty big news. It provides a new perspective on what can be done with a simple nervous system. This suggests that advanced learning may have been one of the most important evolutionary benefits of the nervous system from the very beginning," says Anders Garm.

Seeking the brain cells where memory is housed

The research team has also shown where the learning is happening in these box jellyfish. This has given them unique opportunities for how to now study the precise changes that occur in a nerve cell when it is involved in advanced learning.

"We hope that this can become a supermodel system for looking at cellular processes in the advanced learning of all sorts of animals. We are now in the process of trying to pinpoint exactly which cells are involved in learning and memory formation. Upon doing so, we will be able to go in and look at what structural and physiological changes occur in the cells as learning takes place," says Anders Garm.

If the scientists are able to pinpoint the exact mechanisms in jellyfish involved in learning, the next step will be to find out whether it applies specifically to jellies or if it can be found in all animals.

"Eventually, we will look for the same mechanisms in other animals, to see if this is how memory works in general," says the researcher.

This kind of groundbreaking knowledge could be used for a wealth of purposes, according to Anders Garm.

"Understanding something as enigmatic and immensely complex as the brain is in itself an absolutely amazing thing. But there are unimaginably many useful possibilities. One major problem in the future will undoubtedly be various forms of dementia. I don't claim that we are finding the cure for dementia, but if we can gain a better understanding of what memory is, which is a central problem in dementia, we may be able to lay a building block to better understand the disease and perhaps counteract it," concludes the researcher.

About Tripedalia cystophora

Box jellyfish are a class of jellyfish known for being among the most poisonous animals in the world. They use their venom to catch fish and large shrimp. Tripedalia cystophora has a somewhat milder venom and feeds on tiny copepods.
Box jellyfish do not have a centralized brain like most animals. Instead, they have four parallel brain-like structures, with approximately holds a thousand nerve cells in each. A human brain has approximately 100 billion nerve cells.
Box jellyfish have twenty four eyes distributed among their four brain-like structures. Some of these eyes are image forming, providing box jellyfish with more complex vision than other types of jellyfish.
To find their way through murky mangroves, four of Tripedalia cystophora's eyes look up through the surface of the water and navigate using the mangrove canopies.
Tripedalia cystophora is one of the smallest box jellyfish species, with a body of only about one centimeter in diameter. It lives in the Caribbean Sea and Central Indo-Pacific.
Unlike many jellyfish species, Tripedalia cystophora actually mates as the male captures the female with its tentacles. A female's eggs are then fertilized in their gut system, where they also develop into larvae.

The researchers replicated mangrove swamp conditions in the laboratory, where box jellyfish were placed in a behavioral arena. Here, the researchers manipulated jellyfish behavior by changing the contrast conditions to see what effect this had on their behavior.

They learned that jellyfish learning takes place through failed evasions. That is, they learn from misinterpreting contrast and bumping into roots. Here they combined the visual impression and mechanical shock they got whenever they bumped into a root—and in doing so, learned when to veer away.

"Our behavioral experiments demonstrate that three to five failed evasive maneuvers are enough to change the jellyfish's behavior so that they no longer hit the roots. It is interesting that this is roughly the same repetition rate that a fruit fly or mouse needs to learn," says Anders Garm.

The learning was further verified through electrophysiology and classical conditioning experiments, which also showed where in the jellyfish's nervous system the learning takes place.

The study was conducted by Jan Bielecki from Kiel University and Anders Garm, Sofie Katrine Dam Nielsen and Gösta Nachman from the Department of Biology, University of Copenhagen.

More information: Jan Bielecki et al, Associative learning in the box jellyfish Tripedalia cystophora, Current Biology (2023). DOI: 10.1016/j.cub.2023.08.056. www.cell.com/current-biology/f … 0960-9822(23)01136-3

Journal information: Current Biology

Provided by University of Copenhagen Team discovers new box jellyfish species in Hong Kong

A possible explanation for an increasing trend in the cyclone Genesis Potential Index in the Arabian Sea

by Bob Yirka , Phys.org

A team of Earth scientists and oceanographers affiliated with several institutions in India, working with a colleague from the U.S., has developed possible explanations for some of the factors involved in the observed increasing trend in the cyclone Genesis Potential Index (GPI) in the Arabian Sea.

In their study, reported in the journal npj Climate and Atmospheric Science, the group used data from multiple other studies to learn more about the drivers of cyclonic GPI in the Arabian Sea.

Prior research has suggested that climate change is going to have a major impact on weather around the world. Much effort has gone into studying such changes but they are still difficult to predict. One change already occurring is a reduction in the amount of monsoon rainfall over the Indian subcontinent over the past several decades.

The region has also seen an increase in extreme rainfall events, changes in heat waves and droughts and the number of cyclones that come ashore. Prior research has also shown a dramatic change in the potential for cyclone formation over the Arabian Sea during roughly the same time period.

As the researchers note, it is easy to pin such changes on climate change—much more difficult is to explain just what is happening as the climate changes at a more local level. In this new effort, the research team sought to find all of the factors, or as many as possible, that lead to an increase in cyclonic GPI in the Arabian Sea.

They note that prior research has shown that the factors that lead to changes in GPI in general are related to changes in water temperature, how much heat the ocean is holding, and changes in wind, including rotation near the sea surface. This, they suggest, indicates that one or more of these factors must be responsible for the GPI change in the Arabian Sea.

The team found that over the past 30 years, all such drivers (except wind rotation) would seem to favor an increase in cyclone formation. That led them to ask why that is. They found a shift in the "warm Arctic, cold Eurasian" pattern—a pattern of warm sea surface temperatures over the Arctic Ocean that have been associated with a mass of cold sea surface temperatures over Eurasia. The pattern is believed to be connected to the circulation of upper air over the entire region.

As to why such changes there have occurred, the team cannot say, other than to suggest that it is likely tied to global warming.

More information: P. J. Vidya et al, Intensification of Arabian Sea cyclone genesis potential and its association with Warm Arctic Cold Eurasia pattern, npj Climate and Atmospheric Science (2023). DOI: 10.1038/s41612-023-00476-2

Journal information: npj Climate and Atmospheric Science

Winds of change bring winter rain to eastern Arabia

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