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Comment by Dr. Krishna Kumari Challa on August 6, 2023 at 12:54pm

Multiwavelength Astronomy: The Big Picture

Comment by Dr. Krishna Kumari Challa on August 5, 2023 at 11:19am

Insulin-like hormones critical for brain plasticity, research suggests

Research has identified a mechanism through which insulin-like growth factors facilitate brain plasticity.

The insulin superfamily of hormones, including insulin, insulin-like growth factor 1 (IGF1), and insulin-like growth factor 2 (IGF2), play a crucial role not only in regulating blood sugar, metabolism, and growth, but also in healthy brain development and function, including learning and memory.

These hormones can enter the brain through the bloodstream from the liver or can be synthesized directly in neurons and glial cells within the brain. They bind to receptors, including the IGF1-receptor, activating signals that modulate neuron growth and activity. Disruption of this signaling pathway is involved in cognitive decline and diseases such as Alzheimer's.

In the present work one group of neurons in the hippocampus, CA1 neurons, produced IGF1; another group, CA3 neurons, produced IGF2. When either CA1 or CA3 neurons were activated in a way that mimicked synaptic plasticity, IGF wasreleased. Importantly, when the scientists disrupted the ability of the neurons to produce IGF, the activation of the IGF1-Receptor during plasticity and synaptic growth and strengthening was blocked.

This work reveals a local, autocrine mechanism in neurons that is critical forbrain plasticity. When a synapse undergoes plasticity, IGF is released locally to activate the IGF1-Receptor on the same neuron. Disrupting this mechanism impairs the plasticity, highlighting its critical role in maintaining cognitive health.

This discovery of this new mechanism sheds light on how memories are encoded in the brain and highlights the importance of further study on the insulin superfamily of hormones in the brain. 

 Xun Tu et al, Local autocrine plasticity signaling in single dendritic spines by insulin-like growth factors, Science Advances (2023). DOI: 10.1126/sciadv.adg0666

Comment by Dr. Krishna Kumari Challa on August 5, 2023 at 11:02am

Scientists discover how parasites of viruses drive superbug evolution

In a study published in Cell, scientists  have discovered a new way by which bacteria transmit their genes, enabling them to evolve much faster than previously understood.

The ability to share genetic material is the major driver of microbial evolution because it can transform a benign bacterium into a deadly pathogen in an instant. Phages, the viruses of bacteria, can act as conduits that allow genes to transfer from one bacterium to another by a process known as genetic transduction.

Currently, there are three known mechanisms of transduction: generalized, specialized, and lateral. Lateral transduction was also discovered by the same groups of researchers in 2018, and it is at least one thousand times more efficient than the next most powerful mechanism, generalized transduction.

The new process is termed lateral cotransduction, and the architects behind this new frequency and speed in bacterial evolution are the Staphylococcus aureus pathogenicity islands (SaPIs), which are selfish DNA elements that exploit and parasitise phages and are commonly found integrated into the chromosomes of S. aureus isolates.

S. aureus is a type of bacteria that can cause Staph infections in humans and animals. While it primarily manifests as skin infections, it can become life-threatening if it spreads to the bloodstream and infects organs, bones, or joints.

This newly-discovered process, lateral cotransduction, rivals lateral transduction in terms of efficiency but surpasses the latter in versatility and complexity. While lateral transduction is only known to occur when dormant phages within  bacterial genomesbecome reactivated and initiate reproduction in the lytic cycle, lateral cotransduction can occur during the reactivation process and the infection of new bacterial cells.

Additionally, unlike phages that sacrifice their genes to transmit bacterial host DNA, SaPIs can transfer themselves completely intact with bacterial DNA through lateral cotransduction. This remarkable capability enables them to perpetually repeat the process, making them significantly more potent and efficient in transmitting bacterial genes.

Through the study, scientists  have demonstrated that bacteria can evolve much faster than we understood.

This process likely occurs in various other bacterial species as well. This groundbreaking finding marks a paradigm shift in our understanding of bacterial evolution and will immensely influence the ways we combat antibiotic resistance.

They [phages] could be used to destroy bacteria in the short term but end up spreading harmful genes to other cells in the long term, which could prove to be disastrous. With this new way of understanding the evolutionary mechanisms of disease-causing organisms, it is important for therapeutic phages to be carefully vetted before they are used for therapy.

Melissa Su Juan Chee et al, Dual pathogenicity island transfer by piggybacking lateral transduction, Cell (2023). DOI: 10.1016/j.cell.2023.07.001

Comment by Dr. Krishna Kumari Challa on August 5, 2023 at 10:20am

The mechanisms of the relation between consuming more added sugars and a greater risk of developing kidney stones is not yet known. Because this was an uncontrolled observational trial, it can't yet be ruled out that unknown confounding factors might drive this association.

Further studies are needed to explore the association between added sugar and various diseases or pathological conditions in detail. For example, what types of kidney stones are most associated with added sugar intake? How much should we reduce our consumption of added sugars to lower the risk of kidney stone formation? Nevertheless, these  findings already offer valuable insights for decision-makers.

 Association between added sugars and kidney stones in US adults: data from National Health and Nutrition Examination Survey 2007-2018, Frontiers in Nutrition (2023). DOI: 10.3389/fnut.2023.1226082 , www.frontiersin.org/articles/1 … ut.2023.1226082/full

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Part 2

Comment by Dr. Krishna Kumari Challa on August 5, 2023 at 10:18am

Consuming added sugars may increase risk of kidney stones

Between 7% and 15% of people in North America, between 5% and 9% of people in Europe, and between 1% and 5% of people in Asia suffer from kidney stones. Common symptoms are severe pain, nausea, vomiting, fever, chills, and bloody urine. But kidney stones don't just reduce the quality of life; in the long run, they may lead to infections, swollen kidneys (hydronephrosis), renal insufficiency, and end-stage renal disease. Known risk factors for developing kidney stones include being an adult male, obesity, chronic diarrhea, dehydration, and having inflammatory bowel disease, diabetes, or gout.

Now, a study in Frontiers in Nutrition has shown for the first time that an elevated consumption of added sugars should probably be added to the list of 

risk factors for kidney stones. Added sugars occur in many processed foods, but are especially abundant in sugar-sweetened sodas, fruit drinks, candy, ice cream, cakes, and cookies. It suggests that limiting added sugar intake may help to prevent the formation of kidney stones.

Researchers analyzed epidemiological data on 28,303 adult women and men, collected between 2007 to 2018 within the US National Health and Nutrition Examination Survey (NHANES). Participants self-reported if they had a history of kidney stones. Each participant's daily intake of added sugars was estimated from their recall of their most recent consumption of food and drinks, given twice: once in a face-to-face interview, and once in a telephone interview between three and 10 days later. For example, participants were asked if they had eaten syrups, honey, dextrose, fructose, or pure sugar during the past 24 hours.

Each participants also received a healthy eating index score (HEI-2015), which summarized their diet in terms of the adequacy of beneficial diet components such as fruits, vegetables, and whole grains, and moderation of potentially harmful foods, for example refined grains, sodium, and saturated fats.

The researchers adjusted the odds of developing kidney stones per year during the trial for a range of explanatory factors. These included gender, age, race or ethnicity, relative income, BMI, HEI-2015 score, smoking status, and whether the participants had a history of diabetes.

The researchers showed that after adjusting for these factors, the percentage of energy intake from added sugars was positively and consistently correlated with kidney stones. For example, participants whose intake of added sugars was among the 25% highest in the population had 39% greater odds of developing kidney stones over the course of the study.

Similarly, participants who derived more than 25% of their total energy from added sugars had a 88% greater odds than those who derived less than 5% of their total energy from added sugars.

The results also indicated that participants from "other" ethnicities—for example Native American or Asian people—had higher odds of developing kidney stones when exposed to greater-than-average amounts of added sugars than Mexican American, other Hispanic, non-Hispanic white, and non-Hispanic Black people. People with a greater poverty-income ratio (PIR; i.e., the ratio between their income and the federal poverty level) had greater odds of developing kidney stones when exposed to more added sugars than people at or slightly above poverty level.

Part 1

Comment by Dr. Krishna Kumari Challa on August 5, 2023 at 9:52am

Researchers analyzed the participants' brain activity throughout the whole brain and investigated whether different brain areas work together in a distinct way compared to the baseline scan.

Their findings showed that even though psilocybin, LSD, meditation and hypnosis induce overlapping subjective effects, the underlying brain changes are distinct.

The findings gathered by this team of researchers suggest that while some might report having similar experiences or feelings under these different states of consciousness, what is happening in their brain is actually very different. While psilocybin and LSD appeared to produce similar brain activity, the changes they induced were markedly different from those observed during meditation or hypnosis. This suggests that psychedelics, meditation and hypnosis have distinct underlying mechanisms of action and overall different effects on the brain.

Overall, these results suggest that these three distinct states may have synergistic therapeutic effects and may not therapeutically substitute each other. In the future, they could pave the way for further investigations of their unique strengths and benefits, potentially informing the development of new promising therapeutic strategies for psychiatric disorders.

Flora F. Moujaes et al, Comparing neural correlates of consciousness: from psychedelics to hypnosis and meditation, Biological Psychiatry: Cognitive Neuroscience and Neuroimaging (2023). DOI: 10.1016/j.bpsc.2023.07.003

Part 2

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Comment by Dr. Krishna Kumari Challa on August 5, 2023 at 9:50am

Exploring what happens in the brain under the influence of psychedelics, while meditating and during hypnosis

Changes in a person's "normal" mental state after taking drugs, while meditating, during hypnosis or due to specific medical conditions have been a topic of study for several years now. Some of these mental changes, which are known as altered states of consciousness, have been found by some to have potentially beneficial effects, reducing stress and fostering greater well-being.

Researchers have recently been exploring the potential of psychedelic drugs, such as psilocybin and lysergic acid diethylamide (LSD) for treating depression and other mental disorders. In a recent paper published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, they compared the brains of people who had taken psychedelics to those of others who were meditating or were hypnotized. 

Anecdotally, people often report similarities in experiences induced by hypnosis, meditation, or psychedelics. However, our neurobiological understanding of these states is only just evolving.

While many studies looked at individual altered states of consciousness and how they manifest in the brain, comparisons between these states remain scarce. This study tried to bridge that gap. 

Rather than conducting a single experiment that collectively involved psychedelics, meditation and hypnosis, the researchers analyzed datasets conducted during four distinct experimental trials. The first two trials examined the effects of two different psychedelic drugs on the brain, namely psilocybin and LSD, while the last two focused on hypnosis and meditation.

For the psychedelic studies, they included healthy participants who subsequently received psilocybin, LSD, or a placebo, whereas the meditation and hypnosis studies were conducted with participants who were experts in the respective field to make sure they can reach the state in an MR environment.

During the team's four experimental trials, all participants were asked to simply lay inside an MRI scanner without completing any task or engaging in any activity. The MRI scanner recorded their brain activity both while they were in a normal state of consciousness and under the altered state of consciousness relevant to that trial (i.e., after taking psychedelics, while meditating or while under hypnosis).

Part 1

Comment by Dr. Krishna Kumari Challa on August 4, 2023 at 12:02pm

The Bioconcrete Revolution

Concrete is the most important building material on Earth – and it’s also responsible for a MASSIVE chunk of global carbon emissions. Join George as he discovers how a surprising discovery in 1973 could dramatically change how we make concrete forever.

Comment by Dr. Krishna Kumari Challa on August 4, 2023 at 11:08am

Tree rings reveal that it has not been this warm in the past 1,200 years

A new 1,200 year-long time series based on tree rings shows that the current warming is unprecedented during this period. This is reported by researchers  in the scientific journal Nature.

The Middle Ages and the centuries that followed were not only turbulent socially, but also climatically. Not only was there a "Little Ice Age," but also its opposite: the "Medieval climate anomaly," during which it may have been unusually warm. The latter can clearly be seen in reconstructed temperatures from annual tree rings. In fact, reconstructed Medieval temperatures are often portrayed as higher than today's temperatures.

The previous reconstructions based on tree ring density, in contrast, indicated significantly higher temperatures for the Medieval climate anomaly and lower temperatures for the current warming. "This is critical because such reconstructions are considered when evaluating the accuracy of climate models. If the previous reconstructions were used as a benchmark, this would significantly downplay the human influence on current  climate warming and reduce confidence in model projections.

This has long been a puzzle because there is no known physical explanation for such exceptional Medieval warmth. Climate models are therefore unable to simulate it and instead show only moderately warm temperatures for the Medieval climate anomaly.

Previous reconstructions are based on the width or density of the annual tree rings. Both are very much dependent on temperature, but sometimes other factors play a role in how wide or dense a tree ring gets.

For their study researchers now  used a new method optimized at WSL to directly measure the cell wall thickness of the wood cells in the annual tree rings. Each individual cell in each tree ring records climatic information under which it was formed. By analyzing hundreds, sometimes thousands of cells per ring, extraordinary pure climate information can be obtained.

For their new time series, the researchers measured the cell walls of 50 million cells. These come from 188 living and dead Swedish and Finnish Scots pines (Pinus sylvestris), whose annual rings together cover a period of 1,170 years. Based on these measurements, the researchers then reconstructed the summer temperatures in this region and compared them both with model simulations of the regional climate and with previous reconstructions based on the density of the annual rings.

Researchers have created a new reconstruction based on a particularly precise method to extract temperature information from trees. In contrast to previous work, the new results lead to the same conclusion as the climate models: the Medieval climate anomaly was cooler than previously thought, at least in Scandinavia, where the wood studied originated. Today's warming is thus likely outside the range of natural fluctuations in temperatures over the past 1,200 years, the researchers conclude.

Jesper Björklund et al, Fennoscandian tree-ring anatomy shows a warmer modern than medieval climate, Nature (2023). DOI: 10.1038/s41586-023-06176-4

Comment by Dr. Krishna Kumari Challa on August 4, 2023 at 10:12am

Geostationary satellite reveals widespread midday depression in dryland photosynthesis during 2020 heat wave

We are facing unprecedented heat waves . These conditions have resulted in severe consequences for both human and nature systems, including dire water shortages, rampant wildfires, substantial agricultural losses, and increased human mortality.

The places where these heat waves occur, ecosystems face exacerbated water stress due to more frequent and protracted droughts and heat waves, which can profoundly impair ecosystem photosynthesis and carbon uptake, in turn affecting the global carbon cycle.

Investigating vegetation photosynthesis at various time scales provides valuable insights into vegetation growth, carbon uptake, and environmental interactions. Traditional polar-orbiting satellite observations have aided in monitoring gross primary production (GPP) at longer scales (e.g., monthly, annual), but they are limited in capturing diurnal variations. Fortunately, in recent years, emerging new-generation geostationary satellites with sub-daily sampling capability, provide unique opportunities to study diurnal variations of vegetation photosynthesis and their responses to environmental conditions over the course of day at large spatial scales.

In a recent study, scientists estimated hourly GPP across the Conterminous U.S. based on observations from Geostationary Operational Environmental Satellite-R (GOES-R), and then investigated how the diurnal cycle of photosynthesis responded to the severe late-summer heat wave of 2020. The work is published in the journal Science Advances.

The study provides an exploration of heat wave impacts on the diurnal dynamics of photosynthesis at a continental scale, revealing a widespread midday and afternoon depression of photosynthesis in dryland ecosystems during the heat wave. In the study the researchers examine the environmental regulation of diurnal photosynthesis dynamics across diverse ecosystems, and illustrate how current radiation-based methods for upscaling polar-orbiting satellite snapshots to daily means may under- or overestimate daily GPP.

They found a widespread midday and afternoon depression in ecosystem photosynthesis during the heat wave .

The diurnal metrics exhibit divergent responses to the heat wave across vegetation types and along aridity gradients. Overall, shrubland and grassland are more sensitive to the heat wave than the other vegetation types.

The impact of the heat wave on the diurnal cycle of photosynthesis is predominantly observed in arid and semiarid regions with an aridity index (AI) below 0.6. They found that the largest GPP loss occurred at noon or during the afternoon for the majority of western regions, later than the GPP peak hour during the heat wave year, further substantiating the asymmetric influence of heat waves on diurnal photosynthesis fluctuations.

 Xing Li et al, New-generation geostationary satellite reveals widespread midday depression in dryland photosynthesis during 2020 western U.S. heatwave, Science Advances (2023). DOI: 10.1126/sciadv.adi0775

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