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Comment by Dr. Krishna Kumari Challa on June 1, 2024 at 12:02pm

A new way of healing wounds in diabetics fast

Wounds that are superficial for some can be life-threatening for others. With diabetic wounds, healing can be slow, particularly in the feet, increasing the tissue's susceptibility to infection. Foot ulcers and other diabetic foot complications have similar mortality rates to some cancers, yet progress toward improved treatments has plateaued. Now, researchers may have found a better way to kickstart the healing process.

B ioengineers have developed a multistep strategy that applies different nanomaterials to wounds at different times to support both early- and late-stage healing. In a study published in the journal Biomaterials, the authors' method outperformed a common wound dressing in a diabetic mouse model, closing wounds faster and producing more robust skin tissue.

Clinically, the standard practice for wounds is to keep them clean and use a dressing to protect them while they heal. This approach gets the job done for most injuries but falls short for patients with conditions that interfere with the healing process, such as diabetes. In addition to causing poor circulation and neuropathy, diabetes can disrupt wound healing by impairing the function of various immune cells.

The researchers' analysis also suggests that their approach unexpectedly activated an immune cell population not normally seen in wounds that can resolve inflammation, which highlights a new potential avenue to accelerate healing.

The researchers devised a strategy to treat wounds like these and compared it to a commonly used dressing in a diabetic mouse model.

For the first step, the team fabricated a silk nanomaterial dressing embedded with gold nanorods. Because gold nanoparticles readily convert light to heat, the team was able to direct a laser at dressings placed over fresh wounds in mice, producing heat that quickly sealed them in place and provided a high level of protection.

The strategy, which the authors previously found success with, creates something akin to an instantaneous scab.

This time around, the authors added histamine to the mix, a natural biochemical produced by the immune system that plays important roles in inflammation, blood vessel development, and allergic reactions.

Inflammation dominates the body's initial response to injuries, but eventually subsides to allow the body to rebuild. However, diabetic wounds can get stuck in first gear, maintaining persistent, low-grade inflammation, which can inhibit the healing process.

Since the wound is stalled, the researchers wanted to co-deliver histamine with the dressing, to give a push and bring the inflammation stage to a resolution.

Part 1

Comment by Dr. Krishna Kumari Challa on June 1, 2024 at 10:55am

The team of researchers combined live-cell imaging approaches and molecular genetics to understand why the inhibition of ergosterol synthesis results in cell death in the crop pathogenic fungus Zymoseptoria tritic (Z. tritici). This fungus causes septoria leaf blotch in wheat, a serious disease in temperate climates.
The team observed living Z. tritici cells, treated them with agricultural azoles and analyzed the cellular response. They showed that the previously-accepted idea that azoles kill the pathogen cell by causing perforation of the outer cell membrane does not apply. Instead, they found that azole-induced reduction of ergosterol increases the activity of cellular mitochondria, the "powerhouse" of the cell, required to produce the cellular fuel that drives all metabolic processes in the pathogen cell.
While producing more "fuel" is not harmful in itself, the process leads to the formation of more toxic by-products. These by-products initiate a "suicide" program in the pathogen cell, named apoptosis. In addition, reduced ergosterol levels also trigger a second "self-destruct" pathway, which causes the cell to eat its own nuclei and other vital organelles—a process known as macroautophagy. The authors show that both cell death pathways underpin the lethal activity of azoles. They conclude that azoles drive the fungal pathogen into "suicide" by initiating self-destruction.

The authors found the same mechanism azoles killing pathogen cells in the rice-blast fungus Magnaporthe oryzae

Azoles activate type I and type II programmed cell death pathways in crop pathogenic fungi, Nature Communications (2024). www.nature.com/articles/s41467-024-48157-9

Part 2

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Comment by Dr. Krishna Kumari Challa on June 1, 2024 at 10:53am

Most powerful anti-fungal chemistries cause fungal pathogens to self-destruct

Scientists have discovered that the most widely-used class of antifungals in the world causes pathogens to self-destruct. The  research could help improve ways to protect food security and human lives.

Fungal diseases account for the loss of up to a quarter of the world's crops. They also pose a risk to humans and can be fatal for those with weakened immune systems.

Our strongest weapons against fungal plant diseases are azole fungicides. These chemical products account for up to a quarter of the world agricultural fungicide market, worth more than $3.8 billion per year. Antifungal azoles are also widely used as a treatment against pathogenic fungi which can be fatal to humans, which adds to their importance in our attempt to control fungal disease.

Azoles target enzymes in the pathogen cell that produce cholesterol-like molecules, named ergosterol. Ergosterol is an important component of cellular bio-membranes. Azoles deplete ergosterol, which results in killing of the pathogen cell. However, despite the importance of azoles, scientists know little about the actual cause of pathogen death.

In a new study published in Nature Communications,  scientists have uncovered the cellular mechanism by which azoles kill pathogenic fungi. The paper is titled "Azoles activate type I and type II programmed cell death pathways in crop pathogenic fungi." 

Part 1

Comment by Dr. Krishna Kumari Challa on June 1, 2024 at 10:33am

They calculated stellar populations without and with the presence of dark matter. With dark matter, more massive stars experienced a lower dark matter density, and hydrogen in their core fused more slowly and their evolution was slowed down. But stars in a higher dark matter density region were changed significantly—they maintained equilibrium through dark matter burning with less fusion or no fusion, which led to a new stellar population in an HR region above the main sequence.
The scientists' simulations show that stars can survive on dark matter as a fuel alone and because there is an extremely large amount of dark matter near the Galactic Center, these stars become immortal staying forever young, occupying a new, distinct, observable region of the HR diagram.
Their dark matter model may be able to explain more of the known mysteries. For lighter stars, scientists saw in their simulations that they become very puffy and might even lose parts of their outer layers something similar to this might be observed at the Galactic Center: the so-called G-objects, which might be star-like, but with a gas cloud around them.
There are a limited number of individual stars known to exist so close to the Galactic Center, as the region is extremely bright. Upcoming 30-meter telescopes will be able to see much better into the region, which will allow scientists to better understand the population of its stars and verify or rule out the dark main sequence.

Isabelle John et al, Dark Branches of Immortal Stars at the Galactic Center, arXiv (2024). DOI: 10.48550/arxiv.2405.12267

Part 3

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Comment by Dr. Krishna Kumari Challa on June 1, 2024 at 10:29am

Stars are nuclear ovens, generating heat burning hydrogen via nuclear fusion. The thermal radiation from this reaction, as well as thermodynamic convection of the stellar plasma, exerts an outward force on a star's constituents—mostly hydrogen and helium. That force is balanced by the inward force of self-gravity.

The Hertzsprung–Russell (HR) diagram classifies stars by plotting their luminosity against the effective temperature of their surface. Excluding white dwarfs and red giants, the "main sequence" of this diagram curves from its upper left to lower right, and most stars fall on this curve. (The sun falls near the middle, as their luminosities are plotted as their ratio with the sun's). Stars in different locations on the sequence correspond to stars of different masses and ages.

However, dark matter also exists in the galaxy. Its presence has been inferred by observations that find insufficient ordinary matter to account for the higher-than-expected rotational speeds of stars around the Galactic Center.

Dark matter's density is highest near the center and falls off with the distance from it. It's reasonable to expect it would be incorporated within stars near the center, where dark matter is densest. If so, dark matter annihilation—dark matter particles and antiparticles that collide and produce photons, electrons, etc.—would exert an additional outward pressure within a star and could even dominate over nuclear fusion.
A research team has found that incorporating dark matter power into the dynamics of the innermost stars—those within about a third of a light-year of the center (equivalent to about 8% of the distance to the sun's nearest star)—solves many of the known paradoxes.
To incorporate dark matter annihilation, the group used relatively standard star formation parameters over the evolutionary course of the Milky Way, and dark matter particles just slightly more massive than the proton. Using a stellar evolution computer model, they assumed that stars migrate on the main sequence towards the Galactic Center, then they began to inject dark matter energy into a star's composition. The star then evolved until it reached the red giant branch on the HR diagram, or until it reached an age of 10 billion years, the lifetime of the Milky Way.
Part 2

Comment by Dr. Krishna Kumari Challa on June 1, 2024 at 10:26am

Dark matter could make our galaxy's innermost stars immortal

Stars near the center of our galaxy are acting kind of weird. Dark matter may be the explanation.

A team of scientists have discovered a potential new class of stars that could exist within a light-year of the Milky Way's center that could be operating according to an unusual mechanism: dark matter annihilation. This process would produce an outward pressure on the stars other than hydrogen fusion, keeping them from gravitationally collapsing—and making them essentially immortal, their youth being refreshed constantly. The findings are published  on the arXiv preprint server.

Collectively, the dark matter–powered stars would inhabit a new region of a long-established diagram that classifies stars by their temperature and luminosity, placing them away from the so-called main sequence where the vast majority of stars exist.

Observing our Galactic Center, around which the galaxy's stars rotate, is quite difficult, as the region is extremely bright. A supermassive black hole, Sagittarius A*, sits at the center, with a mass four million times that of the sun. It is a bright source of radio waves, and was imaged in 2022. Stars near Sgr A* orbit it at speeds of several thousands of kilometers per second (compared to the sun's orbital speed of 240 km/s).
These close inner stars, called S-cluster stars, are very puzzling, with properties unlike any others in the Milky Way. Their provenance is unknown, since the environment within about three light-years of the center is considered hostile to star formation. They appear to be much younger than would be expected if they had moved inward from someplace else. Most mysterious of all, they look unusually young, with fewer older stars in the neighborhood than expected, and also unexpectedly, there seem to be many heavy stars.
Part 1

Comment by Dr. Krishna Kumari Challa on June 1, 2024 at 10:19am

This tiny fern has the largest genome of any organism on Earth

In a new study published in the journal iScience, researchers  presented a new record-holder for the largest amount of DNA stored in the nucleus of any living organism on the planet.

Coming in at more than 100 meters of unraveled DNA, the New Caledonian fork fern species Tmesipteris oblanceolata was found to contain more than 50 times more DNA than humans and has dethroned the Japanese flowering plant species Paris japonica, which has held this record since 2010.

In addition, the plant has achieved three Guinness World Records titles for Largest plant genome, Largest Genome, and Largest fern genome for the amount of DNA in the nucleus.

T. oblanceolata is a rare species of fern found on the island nation of New Caledonia, an overseas French territory situated in the Southwest Pacific, about 750 miles east of Australia, and some of the neighboring islands such as Vanuatu. The genus Tmesipteris is an understudied group of plants consisting of about 15 species, most of which occur across a range of Pacific Islands and Oceania.

Until now, scientists have only estimated the size of the genomes for two species of Tmesipteris—T. tannensis and T. obliqua—both of which were found to contain gigantic genomes, at 73.19 and 147.29 gigabase pairs (Gbp) respectively.

The analysis revealed the species T. oblanceolata to have a record-breaking genome size of 160.45 Gbp, which is about 7% larger than that of P. japonica (148.89 Gbp).

Tmesipteris is a unique and fascinating small genus of ferns, whose ancestors evolved about 350 million years ago—well before dinosaurs set foot on Earth—and it is distinguished by its mainly epiphytic habit [it grows mainly on the trunks and branches of trees] and restricted distribution in Oceania and several Pacific Islands.

 Oriane Hidalgo and Jaume Pellicer et al, A 160 Gbp fork fern genome shatters size record for eukaryotes. iScience (2024). DOI: 10.1016/j.isci.2024.109889

Comment by Dr. Krishna Kumari Challa on May 31, 2024 at 11:20am

‘Smart’ antibiotic can kill deadly bacteria while sparing the microbiome

We need our microbiome. But if we take antibiotics, they will disrupt it. 

Now scientists found that a compound called lolamicin targets a group of harmful microbes but does not disturb those that live peacefully in the gut.

Scientists have developed an antibiotic that kills pathogenic Gram-negative bacteria — even those resistant to many other drugs — without impairing the gut microbiome. So far, it has been studied only in mice, but if the compound works in humans, “it could help us dramatically".
However, there is a caveat: the compound’s usefulness “depends on whether bacteria will develop resistance to it in the long run”.
To find a way around the bacteria’s defences, the study’s authors started with compounds that don’t kill the bacteria but are known to inhibit the ‘Lol system’, a group of proteins that is exclusive to Gram-negative bacteria. Tinkering with those compounds produced one that the researchers called lolamicin, which “selectively kills pathogenic bacteria over non-pathogenic bacteria based on differences in Lol proteins between these bacteria.
Lolamicin had anti-microbial effects against more than 130 multidrug-resistant strains of bacteria growing in laboratory dishes.
Mice that developed blood stream infections after exposure to antibiotic-resistant bacteria all survived after being given lolamicin, whereas 87% of those that didn’t receive the compound died within three days.

https://www.nature.com/articles/d41586-024-01566-8?utm_source=Live+...

Comment by Dr. Krishna Kumari Challa on May 31, 2024 at 9:19am

New method advances cancer detection by counting tiny blood-circulating particles

Researcher are reporting a new method to detect cancer which could make cancer detection as simple as taking a blood test. With a 98.7% accuracy rate, the method—which combines PANORAMA imaging with fluorescent imaging—has the potential to detect cancer at the earliest stage and improve treatment efficacy.

The remarkably precise method allows researchers to peer into nanometer-sized membrane sacs, called extracellular vesicles or EVs, that can carry different types of cargos, like proteins, nucleic acids and metabolites, in the bloodstream.

The researchers  observed differences in small EV numbers and cargo in samples taken from healthy people versus people with cancer and are able to differentiate these two populations based on their analysis of the small EVs. The findings came from combining two imaging methods—their previously developed method PANORAMA and imaging of fluorescence emitted by small EVs—to visualize and count small EVs, determine their size and analyze their cargo.

For this research it was a matter of counting the number of small EVs to detect cancer.

Using a cutoff of 70 normalized small EV counts, all cancer samples from 205 patients were above this threshold except for one sample, and for healthy samples, from 106 healthy individuals, all but three were above this cutoff, giving a cancer detection sensitivity of 99.5% and specificity of 97.3%.

To further test the performance of the detection threshold of 70 normalized small EV counts in plasma, the team analyzed two independent sets of samples from stage I-IV or recurrent leiomyosarcoma/gastrointestinal stromal tumors and early-and-late-stage cholangiocarcinoma that were anonymously labeled and mixed in with healthy samples and achieved 100% accuracy.

Nareg Ohannesian et al, Plasmonic nano-aperture label-free imaging of single small extracellular vesicles for cancer detection, Communications Medicine (2024). DOI: 10.1038/s43856-024-00514-x

Comment by Dr. Krishna Kumari Challa on May 31, 2024 at 9:07am

Scientists create the thinnest lens on Earth, enabled by excitons

Lenses are used to bend and focus light. Normal lenses rely on their curved shape to achieve this effect, but physicists have made a flat lens of only three atoms thick that relies on quantum effects. This type of lens could be used in future augmented reality glasses.

Curved-glass lenses work because light is refracted (bent) when it enters the glass, and again when it exits, making things appear larger or closer than they actually are.

Using a single layer of a unique material called tungsten disulfide (WS₂ for short), researchers constructed a flat lens that is half a millimeter wide, but just 0.0000006 millimeters, or 0.6 nanometers, thick. This makes it the thinnest lens on Earth.

Rather than relying on a curved shape, the lens is made of concentric rings of WS₂ with gaps in between. This is called a "Fresnel lens" or "zone plate lens," and it focuses light using diffraction rather than refraction. The size of, and distance between the rings (compared to the wavelength of the light hitting it) determines the lens's focal length. The design used here focuses red light 1 mm from the lens.

A unique feature of this lens is that its focusing efficiency relies on quantum effects within WS2. These effects allow the material to efficiently absorb and re-emit light at specific wavelengths, giving the lens the built-in ability to work better for these wavelengths.
This quantum enhancement works as follows. First, WS2 absorbs light by sending an electron to a higher energy level. Due to the ultra-thin structure of the material, the negatively charged electron and the positively charged "hole" it leaves behind in the atomic lattice stay bound together by the electrostatic attraction between them, forming what is known as an "exciton."
These excitons quickly disappear again by the electron and hole merging together and sending out light. This re-emitted light contributes to the lens's efficiency.
The scientists detected a clear peak in lens efficiency for the specific wavelengths of light sent out by the excitons. While the effect is already observed at room temperature, the lenses are even more efficient when cooled down. This is because excitons do their work better at lower temperatures.

Ludovica Guarneri et al, Temperature-Dependent Excitonic Light Manipulation with Atomically Thin Optical Elements, Nano Letters (2024). DOI: 10.1021/acs.nanolett.4c00694

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