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Comment by Dr. Krishna Kumari Challa on March 21, 2025 at 9:40am

Uniquely shaped, fast-heating nanoparticles halt ovarian tumor growth

New magnetic nanoparticles in the shape of a cube sandwiched between two pyramids represent a breakthrough for treating ovarian tumors and possibly other types of cancer, according to  researchers who developed them.

The scientists say the study underscores the importance of shape in magnetic nanoparticle design and that the findings will potentially revolutionize treatments that use heat to damage or kill cancer cells.

Made of iron oxide and doped with cobalt, the nanoparticles show exceptional heating efficiency when exposed to an alternating magnetic field. Doping refers to adding something as a means of tailoring characteristics.

When the particles accumulate in cancerous tissue after intravenous injection, they're able to quickly rise to temperatures that weaken or destroy cancer cells.

This is the first time systemically injected nanoparticles have been shown to heat tumors beyond 50° C, significantly surpassing the therapeutic threshold of 44° C for effective treatment at a clinically relevant dose.

Prem Singh et al, Precision‐Engineered Cobalt‐Doped Iron Oxide Nanoparticles: From Octahedron Seeds to Cubical Bipyramids for Enhanced Magnetic Hyperthermia, Advanced Functional Materials (2025). DOI: 10.1002/adfm.202414719

Comment by Dr. Krishna Kumari Challa on March 21, 2025 at 9:29am

Now some physicists are saying, 'the standard model is "satisfactory" but some "tensions" are emerging between observations'.

There are several different ways of measuring the expansion of the universe, including looking at the lingering radiation from after the Big Bang, exploding stars called supernovae and how gravity distorts the light of galaxies.

When the DESI team combined their new data with other measurements, they found "signs that the impact of dark energy may be weakening over time," according to a statement.
When we combine all the cosmological data, it favors that the universe's expansion was accelerating at a slightly higher rate around seven billion years ago
But for the moment there is "absolutely not certainty" about this.
Scientists are confident that "evolving dark energy" theory would be a "revolution on the level of the discovery of accelerated expansion,"
The standard cosmological model would have to be different.
The DESI research, which involved three years' worth of observations of 15 million galaxies and quasars, was presented at a conference of the American Physical Society in California.

https://summit.aps.org/events/APR-R08/1

Part 2

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Comment by Dr. Krishna Kumari Challa on March 21, 2025 at 9:21am

Dark energy seems to be changing

Dark energy, the mysterious force thought to be driving the ever-faster expansion of the universe, appears to be changing over time, according to new observations released this week.

If dark energy is in fact weakening, it would likely mean that science's understanding of how the universe works will need to be rewritten.

The new findings come from the Dark Energy Spectroscopic Instrument (DESI), which sits on a telescope at the Kitt Peak National Observatory in the U.S. state of Arizona.

What we are seeing now is deeply intriguing, say the scientists. It is exciting to think that we may be on the cusp of a major discovery about dark energy and the fundamental nature of our universe.

The DESI instrument's thin optical fibers can simultaneously observe 5,000 galaxies or quasars—blazing monsters with a black hole at their heart—for 20 minutes.

This allows scientists to calculate the age and distance of these objects, and create a map of the universe so they can detect patterns and trace its history.

Scientists have known for a century that the universe is expanding, because massive clusters of galaxies have been observed moving away from each other.

In the late 1990s, scientists shocked the field by discovering that the universe's expansion has been speeding up over time.

The name dark energy was given to the phenomenon driving this acceleration, the effects of which seem to be partially offset by ordinary matter—and an also unknown thing called dark matter.

The universe is thought to be made of 70% dark energy, 25% dark matter—and just 5% normal matter.

Science's best understanding of how the universe works, which is called the standard cosmological model, refers to dark energy as being constant—meaning it does not change.

The idea was first introduced by Albert Einstein in his theory of relativity.

Part 1

Comment by Dr. Krishna Kumari Challa on March 21, 2025 at 9:12am

Probiotic boosters shorten fever duration in pediatric trial

A clinical trial  by researchers found a probiotic mixture that significantly shortened fever duration in children with upper respiratory tract infections (URTIs). Children who received a probiotic mixture containing Bifidobacterium breve M-16V, Bifidobacterium lactis HN019, and Lactobacillus rhamnosus HN001 experienced a median fever reduction of two days compared to those given a placebo.

The research is published in the journal JAMA Network Open.

Upper respiratory tract infections are among the most common illnesses affecting young children. Reports indicate that children typically experience five to eight URTIs per year, particularly in the first five years of life. Fever is a frequent symptom and a leading cause of health care visits, often contributing to inappropriate antibiotic use. Antibiotics provide no benefit for viral infections, which account for the majority of cases.

Current symptom management through antipyretics, such as acetaminophen (paracetamol), can temporarily lower body temperature without reducing fever duration. Probiotics have shown potential in modulating immune responses, yet limited clinical evidence exists regarding their role in treating respiratory infections in children.

In the study titled "Probiotics and Fever Duration in Children With Upper Respiratory Tract Infections: A Randomized Clinical Trial," researchers conducted a triple-blind, placebo-controlled randomized clinical trial to evaluate whether a probiotic mixture could reduce fever duration in children with URTIs.

Primary outcome focused on fever duration, defined as the number of days between the first and last recorded febrile day. Secondary outcomes included antibiotic prescription rates after discharge and the incidence of antibiotic-associated diarrhea. Fever duration was recorded by caregivers, with follow-up conducted via telephone to assess compliance and adverse events.

Results indicated that children in the probiotic group experienced a significantly shorter fever duration than those in the placebo group. The median fever duration was 3 days in the probiotic group compared to 5 days in the placebo group.

Poisson regression analysis, adjusted for age, sex, and antibiotic intake, demonstrated that probiotic supplementation was associated with a fever duration risk ratio of 0.64. Adverse events, including constipation and abdominal pain, were infrequent and similar between both groups. No significant effects were observed on antibiotic prescription rates or the incidence of antibiotic-associated diarrhea, and no meaningful safety concerns were identified.

Authors acknowledge the limitations, including the single-center design and reliance on caregiver-reported temperature measurements. The trial did not distinguish between bacterial and viral URTIs, and participants may have received the probiotic at different stages of illness.

Investigators noted that while previous studies on probiotics have primarily focused on prevention rather than treatment, this trial provides evidence supporting their potential therapeutic role as an adjunct treatment for pediatric URTIs.

Silvia Bettocchi et al, Probiotics and Fever Duration in Children With Upper Respiratory Tract Infections, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.0669

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Comment by Dr. Krishna Kumari Challa on March 20, 2025 at 11:28am

Experimental antifungal compound kills multidrug-resistant fungi

The discovery of a new preclinical compound with strong antifungal activity against multidrug-resistant pathogens is described in Nature. The drug, named mandimycin, is a member of a known family of bacterial products with antifungal properties, the polyene macrolides. Unlike known compounds in this family, mandimycin binds to a novel target in the fungal cell membrane and is therefore active against a range of pathogens that are resistant to related compounds.

Mandimycin, does not bind to ergosterol in the cell membrane, the typical target of polyene macrolides. Instead, mandimycin was shown to bind various phospholipids in the fungal cell membrane. This mode of action means that it is effective against fungal pathogens that have evolved resistance to existing antifungal agents that target ergosterol, such as the clinically used agent amphotericin B.

The authors used animal models of infection to test mandimycin against a range of fungal pathogens, including multidrug-resistant Candida auris (a species listed as a priority fungal threat by the WHO), and found that the compound had increased efficacy and reduced nephrotoxicity, as compared with amphotericin B.

Zongqiang Wang, A polyene macrolide targeting phospholipids in the fungal cell membrane, Nature (2025). DOI: 10.1038/s41586-025-08678-9. www.nature.com/articles/s41586-025-08678-9

Comment by Dr. Krishna Kumari Challa on March 20, 2025 at 11:25am

Trees awaken to spring at their own pace—even within the same species in the same forest

Climatic stress events, such as extreme temperatures and prolonged droughts, are increasingly affecting tree growth and phenology—the timing of developmental stages like leaf burst and senescence.

To better understand these processes, researchers set up a long-term experiment with a permanent laser scanning station located at SMEAR II research station.

 The findings are published in the journal Agricultural and Forest Meteorology.

The scanner uses laser light to create centimeter-precise 3D models of individual trees, enabling scientists to track growth and structural changes with unprecedented detail.

Laser scanning time series enable the observation of tree changes over time without interfering with their natural growth. For the first time, scientists were able to accurately measure day-level differences in the phenology of trees in an automated manner. Subsequently, they could study the factors influencing and the effects of these phenological variations within one growth season.

The study focused on silver birch trees and found that species richness and competitive pressure for light in the immediate vicinity influenced the timing of spring leaf burst, while water availability shaped the timing of fall leaf senescence. Additionally, the timing of growth proved critical; for example, early leaf burst was linked to increased crown area growth later in the season. There was a difference of up to 12 days in the time when leaf senescence occurred in the observed trees.

This research highlights how individual trees differ in the timing and duration of their growth period due to the local growth environment, even in a relatively small and homogenous forest area. These insights, like the impact of local water availability on leaf senescence, also help us to understand how changing climate impacts tree phenology and growth within a forest stand.

The experiment provides a better understanding of how local factors drive tree growth.

Mariana Batista Campos et al, Factors and effects of inter-individual variability in silver birch phenology using dense LiDAR time-series, Agricultural and Forest Meteorology (2024). DOI: 10.1016/j.agrformet.2024.110253

Comment by Dr. Krishna Kumari Challa on March 20, 2025 at 9:09am

If helicases are nanomachines, then "ATP," or adenosine trisphosphate, is the fuel. Much like how burning gas drives the pistons of a car engine, burning ATP, the same fuel used to flex your muscles, causes the six pistons of a helicase to unwind DNA.

The study found that as ATP is consumed, it reduces physical constraints that allow the helicase to proceed along the DNA, unwinding more and more of the double strand. Thus, ATP consumption acts as a switch that increases the amount of entropy—or disorder—in the system, freeing the helicase to move along the DNA.
The helicase uses ATP not to pry DNA apart in one motion, but to cycle through conformational changes that progressively destabilize and separate the strands. ATP burning, or hydrolysis, functions like the spring in a mouse trap, snapping the helicase forward and pulling the DNA strands apart.
Among the many discoveries made by the scientists was that two helicases melt the DNA at two sites at the same time to initiate the unwinding. The chemistry of DNA is such that nanomachines move along a single DNA strand in one direction only. By binding at two sites simultaneously, the helicases coordinate so that the winding can happen in both directions with an energy efficiency unique to natural nanomachines.

 Taha Shahid et al, Structural dynamics of DNA unwinding by a replicative helicase, Nature (2025). DOI: 10.1038/s41586-025-08766-w. www.nature.com/articles/s41586-025-08766-w

Part 2

Comment by Dr. Krishna Kumari Challa on March 20, 2025 at 9:07am

Scientists see the first steps of DNA unwinding

For the first time, scientists have witnessed the very moment DNA begins to unravel, revealing a necessary molecular event for DNA to be the molecule that codes all life.

A new study published in Nature, captures the moment DNA begins to unwind, allowing for all the events that follow in DNA replication.

This direct observation sheds light on the fundamental mechanisms that allow cells to faithfully duplicate their genetic material, a cornerstone for growth and reproduction.

Using cryo-electron microscopy and deep learning to observe the helicase Simian Virus 40 Large Tumor Antigen interacting with DNA, the work  provides the most detailed description yet of the very first steps of DNA replication: 15 atomic states that describe how the enzyme helicase forces the unwinding of DNA.

The achievement is not only a milestone in helicase research, but also a milestone in observing the dynamics of any enzyme at atomic resolution.

 For DNA to replicate, the helix must first unwind and break the DNA from a double strand into two single strands.

Upon binding, helicases melt the DNA, breaking the chemical bonds holding the double helix together. They then pull the two strands apart, allowing other enzymes to complete the replication. Without this first step, no DNA can be replicated. In this way, helicases are machines or, because of their size, nanomachines.

Part 1

Comment by Dr. Krishna Kumari Challa on March 19, 2025 at 10:51am

Immediately after the two ancestral populations split, we see a severe bottleneck in one of them—suggesting it shrank to a very small size before slowly growing over a period of one million years.
This population would later contribute about 80% of the genetic material of modern humans, and also seems to have been the ancestral population from which Neanderthals and Denisovans diverged.
However, some of the genes from the population which contributed a minority of our genetic material, particularly those related to brain function and neural processing, may have played a crucial role in human evolution.
The study also found that genes inherited from the second population were often located away from regions of the genome linked to gene functions, suggesting that they may have been less compatible with the majority genetic background. This hints at a process known as purifying selection, where natural selection removes harmful mutations over time.
The fact that we can reconstruct events from hundreds of thousands or millions of years ago just by looking at DNA today is astonishing.

A structured coalescent model reveals deep ancestral structure shared by all modern humans, Nature Genetics (2025). DOI: 10.1038/s41588-025-02117-1

Part 2

Comment by Dr. Krishna Kumari Challa on March 19, 2025 at 10:41am

Genetic study reveals hidden chapter in human evolution

Modern humans descended from not one, but at least two ancestral populations that drifted apart and later reconnected, long before modern humans spread across the globe.

Using advanced analysis based on full genome sequences, researchers  have found evidence that modern humans are the result of a genetic mixing event between two ancient populations that diverged around 1.5 million years ago. About 300,000 years ago, these groups came back together, with one group contributing 80% of the genetic makeup of modern humans and the other contributing 20%.

For the last two decades, the prevailing view in human evolutionary genetics has been that Homo sapiens first appeared in Africa around 200,000 to 300,000 years ago, and descended from a single lineage. However, these latest results, reported in the journal Nature Genetics, suggest a more complex story.

For a long time, it's been assumed that we evolved from a single continuous ancestral lineage, but the exact details of our origins are uncertain. 

This new  research work  shows clear signs that our evolutionary origins are more complex, involving different groups that developed separately for more than a million years, then came back to form the modern human species.

While earlier research has already shown that Neanderthals and Denisovans—two now-extinct human relatives—interbred with Homo sapiens around 50,000 years ago, this new research suggests that long before those interactions—around 300,000 years ago—a much more substantial genetic mixing took place.

Unlike Neanderthal DNA, which makes up roughly 2% of the genome of non-African modern humans, this ancient mixing event contributed as much as 10 times that amount and is found in all modern humans.

The team's method relied on analyzing modern human DNA, rather than extracting genetic material from ancient bones, and enabled them to infer the presence of ancestral populations that may have otherwise left no physical trace. The data used in the study are from the 1000 Genomes Project, a global initiative that sequenced DNA from populations across Africa, Asia, Europe, and the Americas.
The team developed a computational algorithm called cobraa that models how ancient human populations split apart and later merged back together. They tested the algorithm using simulated data and applied it to real human genetic data from the 1000 Genomes Project.

While the researchers were able to identify these two ancestral populations, they also identified some striking changes that happened after the two populations initially broke apart.
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