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Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:30am

Hepatitis C leaves 'scars' in immune cells even after successful treatment

Chronic hepatitis C, caused by the hepatitis C virus, can lead to severe complications such as liver cirrhosis and liver cancer. The advent of highly effective direct-acting antivirals (DAAs) has resulted in high cure rates for this chronic viral infection. However, it has been reported that the immune system of patients does not fully recover even after being cured.

This work provided new insights into the lasting effects of chronic hepatitis C virus (HCV) infection on the immune system, even after the disease has been successfully treated.

The research team has discovered that traces of "epigenetic scars" remain in regulatory T cells and exhibit sustained inflammatory properties long after the virus is cleared from the body. The paper is published in the Journal of Hepatology.

So-Young Kim et al, Epigenetic scars in regulatory T cells are retained after successful treatment of chronic hepatitis C with direct-acting antivirals, Journal of Hepatology (2024). DOI: 10.1016/j.jhep.2024.06.011

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:27am

The researchers further analyzed all bacterial species simultaneously using AI. This revealed a second pattern of 19 different species that were also associated with an increased risk of death.

This is an observational study, and as such, no definitive conclusions can be drawn about the causal roles of particular bacteria.

But, conclude the researchers, "Our results support emerging evidence showing that gut dysbiosis is associated with long-term survival, indicating that gut microbiome targeting therapies might improve patient outcomes, although causal links should be identified first."

 Casper Swarte et al, Multiple indicators of gut dysbiosis predict all-cause and cause-specific mortality in solid organ transplant recipients, Gut (2024). DOI: 10.1136/gutjnl-2023-331441

Part4

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:26am

During a follow-up period of up to 6.5 years, 162 recipients died: 88 kidney, 33 liver, 35 lung and six heart recipients. Forty eight (28%) died from an infection, 38 (23%) from cardiovascular disease, 38 (23%) from cancer, and 40 (25%) from other causes.

The researchers looked at several indicators of gut dysbiosis in these samples: microbial diversity; how much their gut microbiomes differed from the average microbiome of the general population; the prevalence of antibiotic resistance genes; and virulence factors which help bacteria to invade cells and evade immune defenses.
The analysis revealed that the more the gut microbiome patterns of the transplant recipients diverged from those of the general population, the more likely they were to die sooner after their procedure, irrespective of the organ transplanted.

Similar associations emerged for the abundance of antibiotic resistance genes and virulence factors.

The researchers identified 23 bacterial species among all the transplant recipients that were associated with either a heightened or lower risk of death from all causes.
Part3

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:24am

To find out, they looked at the relationship between gut dysbiosis and death from all and specific causes in solid organ transplant recipients among whom the prevalence of gut dysbiosis is much higher than that of the general population. This makes them an ideal group to study the associations between gut dysbiosis and long term survival, say the researchers.

They analyzed the microbiome profiles from 1,337 fecal samples provided by 766 kidney, 334 liver, 170 lung, and 67 heart transplant recipients and compared those with the gut microbiome profiles of 8,208 people living in the same geographical area of northern Netherlands.

The average age of the transplant recipients was 57, and over half were men (784; 59%). On average, they had received their transplant 7.5 years previously.

Part2

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:23am

'Unhealthy' gut microbiome patterns linked to heightened risk of death after organ transplant

'Unhealthy' gut microbiome patterns are linked to a heightened risk of death after a solid organ transplant, finds research published online in the journal Gut.

While these particular microbial patterns are associated with deaths from any cause, they are specifically associated with deaths from cancer and infection, regardless of the organ—kidney, liver, heart, or lung—transplanted, the findings show.

The make-up of the gut microbiome is associated with various diseases, including inflammatory bowel disease and diabetes. But few studies have had the data to analyze the association between the gut microbiome and long term survival, explain the researchers.

And while a shift away from a normal pattern of microbes to an 'unhealthy' pattern, known as gut dysbiosis, has been linked to a heightened risk of death generally, it's not clear whether this might also be associated with overall survival in specific diseases, they add.

To find out, they looked at the relationship between gut dysbiosis and death from all and specific causes in solid organ transplant recipients among whom the prevalence of gut dysbiosis is much higher than that of the general population. This makes them an ideal group to study the associations between gut dysbiosis and long term survival, say the researchers.

Part1

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:16am

First local extinction due to sea level rise identified in the US

The United States has lost its only stand of the massive Key Largo tree cactus in what researchers think is the first local extinction of a species caused by sea level rise in the country.

The Key Largo tree cactus (Pilosocereus millspaughii) still grows on a few scattered islands in the Caribbean, including northern Cuba and parts of the Bahamas. In the United States, it was restricted to a single population in the Florida Keys, first discovered in 1992 and monitored intermittently since.

Salt water intrusion from rising seas, soil depletion from hurricanes and high tides, and herbivory by mammals had put significant pressure on the population. By 2021, what had been a thriving stand of about 150 stems was reduced to six ailing fragments, which researchers salvaged for off-site cultivation to ensure their survival.

"Unfortunately, the Key Largo tree cactus may be a bellwether for how other low-lying coastal plants will respond to climate change," say scientists. 

But don't worry, the researchers are studying and trying to rescue the remnants of a dwindling stock of this cactus. 

 First U.S. vascular plant extirpation linked to sea level rise? Pilosocereus millspaughii (Cactaceae) in the Florida Keys, U.S.A., Journal of the Botanical Research Institute of Texas (2024). DOI: 10.17348/jbrit.v18.i1.1350

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:12am

New study sheds light on brain responses to emotionally-charged scenes

The ability to recognize and respond to emotionally-charged situations is essential to a species' evolutionary success. A new study published in Nature Communications advances our understanding of how the brain responds to emotionally charged objects and scenes.

This new  research reveals that the occipital temporal cortex is tuned not only to different categories of stimuli but it also breaks down these categories based on their emotional characteristics in a way that is well suited to guide selection between alternate behaviours.

The researchers analyzed the brain activity of a small group of volunteers viewing over 1,500 images depicting natural emotional scenes such as a couple hugging, an injured person in a hospital bed, a luxurious home, and an aggressive dog. Participants were asked to categorize the images as positive, negative or neutral and to also rate the emotional intensity of the images.

A second group of participants picked the behavioural responses that best matched each scene.

Using cutting-edge modeling of brain activity divided into tiny cubes (of under 3mm3), the study discovered that the occipital temporal cortex (OTC), a region at the back of the brain, is tuned to represent both the type of stimulus (single human, couple, crowd, reptile, mammal, food, object, building, landscape etc.) and the emotional characteristics of the stimulus—whether it's negative, positive or neutral and also whether it's high or low in emotional intensity. 

Machine learning showed that these stable tuning patterns were more efficient in predicting the behaviors matched to the images by the second group of participants than could be achieved by applying machine learning directly to image features—suggesting that the OTC efficiently extracts and represents the information needed to guide behaviour.

These findings expand our knowledge of how the human brain represents emotional natural stimuli.

Occipital-temporal cortical tuning to semantic and affective features of natural images predicts associated behavioral responses, Nature Communications (2024). DOI: 10.1038/s41467-024-49073-8

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:04am

So the researchers have created a new system here that provides a powerful platform for deepening their understanding of the time crystal phenomenon in a way that comes very close to Frank Wilczek's original idea.
Precise, self-sustained oscillations could be used for sensors.

Xiaoling Wu et al, Dissipative time crystal in a strongly interacting Rydberg gas, Nature Physics (2024). DOI: 10.1038/s41567-024-02542-9. On arXiv: arxiv.org/html/2305.20070v3

Part 2

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 7:03am

Scientists successfully create a time crystal made of giant atoms

A crystal is an arrangement of atoms that repeats itself in space, in regular intervals: At every point, the crystal looks exactly the same. In 2012, Nobel Prize winner Frank Wilczek raised the question: Could there also be a time crystal—an object that repeats itself not in space but in time? And could it be possible that a periodic rhythm emerges, even though no specific rhythm is imposed on the system and the interaction between the particles is completely independent of time?

For years, Frank Wilczek's idea has caused much controversy. Some considered time crystals to be impossible in principle, while others tried to find loopholes and realize time crystals under certain special conditions.

Now, a particularly spectacular kind of time crystal has successfully been created at Tsinghua University in China, with the support from TU Wien in Austria. The team used laser light and special types of atoms, namely Rydberg atoms, with a diameter that is several hundred times larger than normal.  The results have been published in the journal Nature Physics.

The ticking of a clock is also an example of a temporally periodic movement. However, it does not happen by itself: Someone must have wound the clock and started it at a certain time. This starting time then determined the timing of the ticks. It is different with a time crystal:

According to Wilczek's idea, a periodicity should arise spontaneously, although there is actually no physical difference between different points in time.

The tick frequency is predetermined by the physical properties of the system, but the times at which the tick occurs are completely random; this is known as spontaneous symmetry breaking.

How this new work was done: 

Laser light was shone into a glass container filled with a gas of rubidium atoms. The strength of the light signal that arrived at the other end of the container was measured.

This is actually a static experiment in which no specific rhythm is imposed on the system. 

The interactions between light and atoms are always the same, the laser beam has a constant intensity. But surprisingly, it turned out that the intensity that arrives at the other end of the glass cell begins to oscillate in highly regular patterns.

The key to the experiment was to prepare the atoms in a special way: The electrons of an atom can orbit the nucleus on different paths, depending on how much energy they have. If energy is added to the outermost electron of an atom, its distance from the atomic nucleus can become very large.

Part1

In extreme cases, it can be several hundred times further away from the nucleus than usual. In this way, atoms with a giant electron shell are created—so-called Rydberg atoms.

If the atoms in their glass container are prepared in such Rydberg states and their diameter becomes huge, then the forces between these atoms also become very large.

And that in turn changes the way they interact with the laser. If you choose laser light in such a way that it can excite two different Rydberg states in each atom at the same time, then a feedback loop is generated that causes spontaneous oscillations between the two atomic states. This in turn also leads to oscillating light absorption. All by themselves, the giant atoms stumble into a regular beat, and this beat is translated into the rhythm of the light intensity that arrives at the end of the glass container.

Comment by Dr. Krishna Kumari Challa on July 10, 2024 at 6:49am

Initially, the researchers investigated whether cell growth can be regulated with an externally administered substance. Once successful, they examined whether the cells functioned normally.

They used stem cells to create insulin-producing β-cells that they then transplanted into laboratory animals. The cells regulated the blood glucose levels of the animals throughout the almost six-month experiment.
The cells are also able to differentiate into other tissue types as usual, and the researchers have not observed any differences in them other than their inability to proliferate without their say-so.
Stem cells are very primitive cells, as they have to be able to divide in abundance and develop in many different directions. They have potential for a range of purposes, but their primitive nature also poses a problem: What if some cells are not differentiated, but continue to grow in a primitive form? According to the scientists of the study, the research group's solution enables the efficient proliferation of cells during production, which can be halted at the desired time, such as following transplantation.
The solution also makes it possible to edit cells without fear of adverse effects of the editing itself. For example, cells can be made into something that the recipient's immune system does not recognize.
Previously, such cells would have been highly risky, as the immune system also monitors the onset of cancer. Now, that risk is very small or non-existent. Ideally, these cells could be turned into products suited to everyone and, when necessary, quickly deployed.

Rocio Sartori-Maldonado et al, Thymidylate synthase disruption to limit cell proliferation in cell therapies, Molecular Therapy (2024). DOI: 10.1016/j.ymthe.2024.06.014

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