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Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 12:27pm

Brain mechanisms underpinning loss of consciousness identified

The shift from an awake state to unconsciousness is a phenomenon that has long captured the interest of scientists and philosophers alike, but how it happens has remained a mystery—until now. Through studies on rats, a team of researchers at Penn State has pinpointed the exact moment of loss of consciousness due to anesthesia, mapping what happens in different brain regions during that moment.

The study has implications for humans as well as for other types of loss of consciousness, such as sleep, the researchers said. They published their results in Advanced Science.

In this study the researchers combined two different methods: electrophysiology studies and functional magnetic resonance imaging (fMRI). By measuring electrophysiological signals—or electrical activity—in the brain very quickly over time, the researchers determined the precise moment that the rat transitioned from an awake state to an unconscious one.  

They next overlaid this time-stamped data with the fMRI map of activity in the whole brain to investigate different regions of the brain during that transition.

They  found that there were three regions in the brain that showed transient changes in their activities during the moment of lost consciousness: the medial prefrontal cortex, the hippocampus and the thalamus.

While these regions have been implicated in unconscious states in the existing scientific literature, this new research was the first to indicate how these regions might interact with each other and what kind of role they might play during the moment of loss of consciousness.

The researchers said previous work also did not indicate whether the activity in those three regions was a cause or an effect of loss of consciousness.

The results suggest that loss of consciousness may be triggered by sequential events in these three regions, while activity increases in other cortical regions may be a consequence, rather than a cause, of loss of consciousness.

The results do provide new insights into the roles of these brain regions in loss of consciousness.

Xiaoai Chen et al, Sequential Deactivation Across the Hippocampus‐Thalamus‐mPFC Pathway During Loss of Consciousness, Advanced Science (2024). DOI: 10.1002/advs.202406320

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 12:08pm

Toxoplasma gondii parasite uses unconventional method to make proteins for evasion of drug treatment, research reveals

A study by  Medicine researchers sheds new light on how Toxoplasma gondii parasites make the proteins they need to enter a dormant stage that allows them to escape drug treatment. The research is published in the Journal of Biological Chemistry.

Toxoplasma gondii is a single-celled parasite that people catch from cat feces, unwashed produce or undercooked meat. The parasite has infected up to one-third of the world's population, and after causing mild illness, it persists by entering a dormant phase housed in cysts throughout the body, including the brain.

Toxoplasma cysts have been linked to behavior changes and neurological disorders like schizophrenia. They can also reactivate when the immune system is weakened, causing life-threatening organ damage.

While drugs are available to put toxoplasmosis into remission, there is no way to clear the infection. A better understanding of how the parasite develops into cysts would help scientists find a cure.

 Researchers have shown that Toxoplasma forms cysts by altering which proteins are made. Proteins govern the fate of cells and are encoded by mRNAs.

But mRNAs can be present in cells without being made into protein. Researchers have  shown that Toxoplasma switches which mRNAs are made into protein when converting into cysts.

Researchers examined the so-called leader sequences of genes named BFD1 and BFD2, both of which are necessary for Toxoplasma to form cysts.

mRNAs not only encode for protein, but they begin with a leader sequence that contains information on when that mRNA should be made into protein.

All mRNAs have a structure called a cap at the beginning of their leader sequence. Ribosomes, which convert mRNA into protein, bind to the cap and scan the leader until it finds the right code to begin making the protein.

What the researchers now found is during cyst formation, BFD2 is made into protein after ribosomes bind the cap and scan the leader, as expected. 

But BFD1 does not follow that convention. Its production does not rely on the mRNA cap like most other mRNAs."

The team further showed that BFD1 is made into protein only after BFD2 binds specific sites in the BFD1 mRNA leader sequence. This is a phenomenon called cap-independent translation, which is more commonly seen in viruses.

Finding it in a microbe that has cellular anatomy like our own was surprising.

Vishakha Dey et al, Cap-independent translation directs stress-induced differentiation of the protozoan parasite Toxoplasma gondii, Journal of Biological Chemistry (2024). DOI: 10.1016/j.jbc.2024.107979

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 11:09am

Human disruption is driving 'winner' and 'loser' tree species shifts across Brazilian forests, study shows

An international team of researchers examined a unique dataset of more than 1,200 tropical tree species over more than 270 forest plots across six regions of Brazilian Amazon and Atlantic forests that have been altered by people through activities such as deforestation and local disturbances like logging, hunting and burning.

Fast-growing and small-seeded tree species are dominating Brazilian forests in regions with high levels of deforestation and degradation, a study shows. This has potential implications for the ecosystem services these forests provide, including the ability of these "disturbed" forests to absorb and store carbon. This is because these "winning" species grow fast but die young, as their stems and branches are far less dense than the slow growing tree species they replace.

Wildlife species adapted to consuming and dispersing the large seeds of tree species that are being lost in human-modified landscapes may also be affected by these shifts.

Authors of the study, "Winner-loser plant trait replacements in human-modified tropical forests" published in Nature Ecology & Evolution, say their findings highlight the urgent need to conserve and restore tropical forests, prevent degradation, and implement measures to protect and boost populations of the large-bodied birds like toucans and mammals such as spider monkeys that disperse the seeds of "losing" slow-growing large-seeded tree species.

The researchers looked at the overall structure of the landscapes surrounding each forest plot and, using multiple statistical models, they were able to identify the causal effects of habitat loss, fragmentation and local degradation on the composition of forests, as well as identifying the attributes of so-called "winners" and "losers" species.

They found that the tree species dominating landscapes with high forest cover tend to have dense wood and large seeds, which are primarily dispersed by medium to large-bodied animals typical of Brazil's rainforests. 

In contrast, in highly deforested landscapes, where remaining forests face additional human disturbances, these tree species are losing out to so-called 'opportunistic' species, which have softer wood and smaller seeds consumed by small, mobile, disturbance-adapted birds and bats. These species typically grow faster and have greater dispersal capacity.

The researchers found this was happening despite differing geography, climate and land-use contexts.

This study highlights the urgent need to strengthen the conservation and restoration of tropical forests to preserve these vital ecosystems.

Tropical forests constitute the most important reservoir of terrestrial biodiversity. They play a major role in absorbing greenhouse gases and provide essential ecosystem services. Yet they are victims of rapid deforestation and fragmentation, with the loss of 3 to 6 million hectares per year over the last two decades.

Winner-loser plant trait replacements in human-modified tropical forests, Nature Ecology & Evolution (2024). DOI: 10.1038/s41559-024-02592-5

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 10:57am

To test this antidote, they injected hydrogen sulfide-treated mice with met-hemoCD-I. The results were very promising—mice injected with met-hemoCD-I showed improved survival rates compared to mice that were not given the antidote. Additionally, CcO activity in the brain and heart tissues (which had decreased because of poisoning) recovered and returned to normal.
Another aspect of met-hemoCD-I that makes it a very promising antidote is its demonstrated safety—it was found that injected met-hemoCD-I was excreted in the urine of the rats without undergoing any chemical decomposition in their body.

The results of this study show that hemoCD-Twins could be used as a powerful antidote to treat carbon monoxide, hydrogen cyanide, and now hydrogen sulfide poisoning without the risk of any side effects.
Using hemoCD-Twins, we can provide one powerful solution for multiple gas poisoning, even if the cause of poisoning is unknown.
Clinical trials are about to be started with this antidote.

 Nakagami, A., et al. Detoxification of hydrogen sulfide by synthetic heme model compounds, Scientific Reports (2024). DOI: 10.1038/s41598-024-80511-1

Part 2

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 10:48am

New antidote could save lives from deadly hydrogen sulfide gas

Hydrogen sulfide, a colorless gas that smells like rotten eggs, is produced naturally from decaying matter. This gas is lethal to breathe in, and hydrogen sulfide present in high concentrations can cause death very rapidly.

Its relative density is also greater than air, causing it to accumulate at lower altitudes and posing an enormous threat to workers at sites, such as manholes, sewage systems and mining operations.

Why is hydrogen sulfide so dangerous? It binds strongly to the heme-containing cytochrome c oxidase (CcO) enzyme and blocks the cellular process of aerobic (oxygen-dependent) respiration.
What is even more concerning is that, as of now, there is no identified antidote that can treat hydrogen sulfide poisoning. Hence, there is an urgent need to develop therapeutic agents that can be stored for long durations and are effective against hydrogen sulfide poisoning immediately.

A study  published online on December 10, 2024, in Scientific Reports has proposed a novel antidote for hydrogen sulfide poisoning.

Researchers decided to tackle this problem by using artificial heme-model compounds that would have a higher affinity towards hydrogen sulfide than the native hemes present in our bodies.

They  have developed and studied synthetic heme-model compounds (hemoCDs) over the last two decades.

In this study, they decided to test if  two of those complexes had the potential to "scavenge" hydrogen sulfide in an aqueous medium. Interestingly, they found that met-hemoCD-I in particular had a very high affinity for hydrogen sulfide under normal physiological conditions—almost 10 times higher than that of human met-hemoglobin.

Met-hemoCD-I was able to convert toxic hydrogen sulfide into nontoxic sulfite and sulfate ions, indicating that it could be used to treat hydrogen sulfide poisoning.

Part 1

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 10:32am

The analysis showed that sea-surface temperatures dropped by 3°C as an after-effect of the merging of the cyclones, and deep, cold water masses were churned upwards towards the surface from a depth of 200 meters in a process known as "upwelling." The cooling effect was "exceptionally high" in relation to the cyclones' intensity, the researchers observed.

The highest wind speeds of around 130 kilometers per hour were reached on 11 April, after the merging of the cyclones, and corresponded to Category 1 on the Hurricane Scale. The observed cooling and the depth of the upwelling, on the other hand, were of a scale observed in Category 4 or 5 hurricanes.
The researchers were particularly surprised by the strength of the upwelling: there were periods when the deep-water masses rose to the sea surface at a speed of up to 30 meters per day. By comparison, the typical upward velocity of the ocean is only between 1 and 5 meters per day.

In this specific case, a downward velocity of the ocean was observed shortly before the cyclones merged. Thanks to satellite technology and autonomous deep-sea ARGO floats, they were able to demonstrate how the rotation of the cyclones transports cold water from the depths of the ocean to the surface.
Although encounters between tropical cyclones during their one to two-week lifespan have been rare to date, according to climate models, the number and intensity of tropical cyclones is likely to increase as a result of global warming—and by extension also the likelihood of full-blown hurricane-force cyclones colliding.
This could result in "the most extreme interactions between the ocean and the atmosphere," the authors of the paper write. The fact that the merging of two cyclones can lead to an abrupt change of course also makes it more difficult to predict how they will behave afterwards.
They also point to another important consequence: "As a result of the interactions of a cyclone with the ocean and the upwelling of cold, deep water, the ocean absorbs additional heat from the air and then transports it to higher latitudes—a crucial process that influences the climate worldwide."
In addition, cyclones also convert thermal energy into mechanical energy which they then transport to higher latitudes as they progress.

Oliver Wurl et al, Intense Cooling of the Upper Ocean with the Merging of Tropical Cyclones: A Case Study in the Southeastern Indian Ocean, Tellus A: Dynamic Meteorology and Oceanography (2024). DOI: 10.16993/tellusa.4083

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 10:29am

What happens in the ocean when two cyclones collide?

In April 2021, two tropical cyclones, Seroja and Odette, collided in the Indian Ocean northwest of Australia. Researchers   now studied how this rare phenomenon affected the ocean.

According to their case study, the rendezvous caused an unusual cooling of the surface water and an abrupt change in the direction of the combined storm. Since the frequency and intensity of tropical cyclones are increasing as a result of global warming, it is possible that such encounters—and thus more extreme air-sea interactions—will become more frequent in the future, they conclude.

Tropical cyclones (TCs) not only whip up air masses in the atmosphere, they also churn up water masses in the areas of the ocean that are in their path. When two cyclones collide and merge, these interactions between the ocean and the atmosphere can intensify considerably.

Researchers reported this  in a paper published in the journal Tellus A: Dynamic Meteorology and Oceanography.

The researchers analyzed the encounter between two relatively weak tropical cyclones in the Indian Ocean in 2021, TC Seroja and TC Odette, and found that effects occurred that have otherwise only been observed with much stronger cyclones. Since the frequency and intensity of tropical cyclones is increasing as a result of global warming, this type of convergence—and the resulting extreme interactions between air and sea—could become more frequent in the future, the study concludes.

Researchers combined satellite data and measurements obtained from ARGO floats and autonomous drifters with numerical modeling. These sources provided the researchers with information about factors such as salinity and water temperatures between the sea surface and depths of up to 2,000 meters as well as data about upward and downward (vertical) flow velocities. In addition to these data, they analyzed upward and downward (vertical) flow velocities using data from numerical models. 

The encounter between the two cyclones lasted for around a week. On 6 April they came within approximately 1,600 kilometers of one another. Seroja first of all stalled the smaller cyclone Odette and then merged with it three days later.

After the two cyclones merged, TC Seroja abruptly changed course by 90 degrees on 9 April. This chain of events not only influenced weather patterns but also triggered a previously unobserved interaction with the ocean underneath.

Part 1

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 10:12am

AI's power demands driving toxic air pollution, study finds

Computer processing demands for artificial intelligence, or AI, are spurring increasing levels of deadly air pollution from power plants and backup diesel generators that continuously supply electricity to the fast-growing number of computer processing centers.

This air pollution is expected to result in thousands of premature deaths a year by 2030.

Total public health costs from cancers, asthma, other diseases, and missed work and school days are getting mind boggling. 

Such are findings of a study by UC Riverside and Caltech scientists published online this week on the arXiv preprint server. Yet, these human and financial costs appear overlooked by the tech industry.

Yuelin Han et al, The Unpaid Toll: Quantifying the Public Health Impact of AI, arXiv (2024). DOI: 10.48550/arxiv.2412.06288

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 9:53am

Tourism leads the pack in growing carbon emissions, study shows

A University of Queensland-led study shows greenhouse gas emissions from tourism have been growing more than two times faster than those from the rest of the global economy. The research is published in Nature Communications.

Rapid expansion in travel demand has meant carbon  from tourism activities accounts for 9% of the world's total emissions.

Without urgent interventions in the global tourism industry, we anticipate annual increases in emissions of 3 to 4%, meaning they will double every 20 years, say scientists.

This does not comply with the Paris Agreement which requires the sector to reduce its emissions by more than 10% annually.

"The major drivers behind the increasing emissions are slow technology improvements and a rapid growth in demand.

The study involved researchers from UQ, Griffith University, the University of Sydney and Linnaeus University (Sweden), and tracked international and domestic travel for 175 countries.

It found tourism's global carbon footprint increased from 3.7 gigatons (Gt) to 5.2 Gt between 2009 and 2019. The most net emissions were reported in aviation, utilities and private vehicle use for travel.

The emissions growth rate for tourism was 3.5% per annum during the decade while global emissions increased by 1.5% per annum from 50.9 Gt to 59.1 Gt.

The United States, China, and India dominated the list and were responsible for 60% of the total increase in tourism emissions across the study period. Australia ranked in the top 20 countries that together contributed three quarters of the total tourism carbon footprint in 2019.

The biggest carbon challenge in tourism is air travel.

Reducing long-haul flights is one of the recommendations scientists have put forward to help the industry lower its emissions.

Cutting back on marketing long-haul travel and identifying a national growth threshold would also help rein in the rapid expansion of emissions.

At a local level, tourism operators could look to renewable electricity for accommodation, food and recreational activities and switch to electric vehicles for transport.

Ya-Yen Sun, Drivers of global tourism carbon emissions, Nature Communications (2024). DOI: 10.1038/s41467-024-54582-7. www.nature.com/articles/s41467-024-54582-7

Comment by Dr. Krishna Kumari Challa on December 11, 2024 at 9:36am

The team conducted their experiments at the National High Magnetic Field Laboratory in Florida. The lab's hybrid magnet creates the most powerful sustained magnetic field in the world, roughly 900,000 times stronger than the Earth's magnetic field. The field is so strong it can levitate small objects such as water droplets.

The researchers cooled down a piece of ZrSiS to -452°F—only a few degrees above absolute zero, the lowest possible temperature—and then exposed it to the lab's powerful magnetic field while hitting it with infrared light to see what it revealed about the quantum interactions inside the material.
When a magnetic field is applied to any material, the energy levels of electrons inside that material become quantized into discrete levels called Landau levels.
The levels can only have fixed values, like climbing a set of stairs with no little steps in between. The spacing between these levels depends on the mass of the electrons and the strength of the magnetic field, so as the magnetic field increases, the energy levels of the electrons should increase by set amounts based entirely on their mass—but in this case, they didn't.

Using the high-powered magnet in Florida, the researchers observed that the energy of the Landau level transitions in the ZrSiS crystal followed a completely different pattern of dependence on the magnetic field strength. Years ago, theorists had labeled this pattern the "B2/3 power law," the key signature of semi-Dirac fermions.

Yinming Shao et al, Semi-Dirac Fermions in a Topological Metal, Physical Review X (2024). DOI: 10.1103/PhysRevX.14.041057
Part 2

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