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Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:42am

Most normal matter in the universe isn't found in planets, stars or galaxies

Only about 9% of the universe’s normal (baryonic) matter is found in stars and cold gas within galaxies, while 76% resides in the intergalactic medium and 15% in galaxy halos. This distribution matches Big Bang predictions, confirming that most normal matter exists as diffuse gas between galaxies, not in visible structures. Dark matter and dark energy remain the dominant, poorly understood components.

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:42am

So in his latest study, titled "Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation" and published in the Journal of Spacecraft and Rockets, researchers investigated ways to create commercial opportunities for space operators and debris remediators to clean up dangerous junk.

The study analyzed three possible scenarios of debris cleanup—controlled reentry back to Earth, uncontrolled reentry back to Earth, and recycling in space. All three methods would require a space debris remediation satellite - a vehicle designed to capture and remove space junk from orbit. 

In the uncontrolled re-entry scenario, the remediation service vehicle would grab the debris from the orbit path it flies in and bring it down to about 350 kilometers away from Earth. The piece of debris would continue orbiting around our planet until it entered the atmosphere and either burned or landed someplace.

It will either burn or drop somewhere on Earth, but we don't know where because it depends on the atmospheric drag it receives. This uncontrolled reentry method is the cheapest as the remediation vehicle doesn't have to fly long distances.

In the controlled reentry scenario, the remediation service vehicle would bring the debris much closer to Earth, down to about 50 kilometers.  Controlled reentry is more expensive because the servicer needs to bring the debris down closer to Earth and then fly up again to get the next piece of debris. That consumes more energy and more fuel than an uncontrolled reentry .

In the recycling scenario, the debris would be transported from its original orbit to a recycling center up in space. The transportation would require fuel, adding to the cost, but a lot of energy would also be saved by reusing aluminum, the metal commonly used in spacecraft, up in orbit rather than having to bring it up from Earth.

It takes about $1,500 per kilogram to launch anything from Earth to space.  . So if you don't have to launch from Earth, it's a benefit.

Space operators stand a lot to gain from debris removal. Their satellites can operate more safely and efficiently, so they save money on fuel and operations, since they don't have to make extra maneuvers to avoid collisions.

Asaad Abdul-Hamid et al, Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation, Journal of Spacecraft and Rockets (2025). DOI: 10.2514/1.a36465

https://phys.org/news/2025-12-space-debris-poses-threat-cleanup.htm...

part2

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:41am

Space debris poses growing threat, but new study suggests cleanup is feasible

High up in Earth's orbit, millions of human-made objects large and small are flying at speeds of over 15,000 miles per hour. The objects, which range from inactive satellites to fragments of equipment resulting from explosions or collisions of previously launched rockets, are space debris, colloquially referred to as space junk. Sometimes the objects collide with each other, breaking into even smaller pieces.

No matter the size, all of this debris poses a problem. Flying at high speeds caused by prior launches or explosions, they create danger for operational satellites and spacecraft, which are vital for the efficacy of modern technologies like GPS, digital communication and weather forecasting. At orbital speeds, even tiny fragments can cause significant damage to operational equipment, endangering future space missions and the people who would participate in them. 

Even if a tiny, five-millimeter object hits a solar panel or a solar array of a satellite, it could break it .  And we have over 100 million objects smaller than one centimeter in orbit. So if you want to avoid a collision, you have to maneuver your spacecraft, which takes up fuel and is costly. Additionally, we have humans on the International Space Station who sometimes must go outside the spacecraft where the space debris can hit them too. It's really dangerous.

Cleaning up space junk is technologically challenging and expensive. Furthermore, there are currently no incentives for countries or private companies to do so. Without binding international regulations or an enforceable "polluter pays" principle with consequences for noncompliance, the circumstances have led to a "cosmic free-for-all."

Part1

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:40am

Tattoos might put the immune system at risk

 Studies in mice suggest that the pigment used in tattoos accumulates in the lymph nodes and might affect immune responses. Researchers found that ink remained in the lymph nodes for months and had varying effects: it weakened the animals’ response to a COVID vaccine but increased the reaction to an influenza vaccine.

https://www.pnas.org/doi/10.1073/pnas.2510392122

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:37am

Gut bacteria's hidden toxin acts as DNA glue, fueling colorectal cancer risk

Colibactin is a powerful toxin produced by Escherichia coli and other bacteria living in the human gut. This highly unstable bacterial product causes mutations in DNA that have been linked to colorectal cancer. Because it breaks down quickly, isolating and studying it has been difficult, but now scientists  have discovered exactly how colibactin attacks DNA.

Using advanced tools such as mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy, the team studied the toxin at the atomic level, as reported in a paper published in the journal Science. The scientists overcame colibactin's instability by growing toxin-producing bacteria directly next to strands of DNA in the lab. Consequently, colibactin attacked the genetic material almost as soon as it was made. 

The study authors discovered that the toxin doesn't target genetic material at random. It homes in on DNA sequences with high quantities of adenine and thymine bases. The way it damages DNA is by creating a bridge-like connection, called an interstrand cross-link (ICL), between the two strands of the DNA helix. In effect, the toxin acts like glue, binding the two strands together. This damage is permanent and prevents the cell from correctly reading or copying its DNA, which ultimately results in genetic errors that can lead to cancer.

The researchers also revealed that the damage occurs at the same place, in the minor groove. This is the narrow, shallow groove that is formed where the DNA's backbones are closest together. And the reason is the toxin has an unstable, positively charged core that is attracted to the negatively charged, AT-rich minor groove. So they fit together like a lock and key.

The research is a significant advance in our understanding of the direct link between gut microflora and cancer risk. The discovery that colibactin binds to DNA at a specific site explains the characteristic DNA mutations doctors observe in colorectal cancer patients. 

Now that scientists know the structure of the ICL bridge and the mechanism of attack, it can help them develop diagnostic tools to screen people at higher risk and design therapeutics to neutralize the unstable core. It could even inform new ways to reduce cancer risk through dietary changes or treatments that reduce the number of colibactin-producing bacteria in the gut. 

Erik S. Carlson et al, The specificity and structure of DNA cross-linking by the gut bacterial genotoxin colibactin, Science (2025). DOI: 10.1126/science.ady3571

Orlando D. Schärer, Molecular basis of DNA cross-linking by bacteria, Science (2025). DOI: 10.1126/science.aec9205

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:36am

Abdominal obesity and muscle loss increase the risk of death by 83% after age 50, study finds

A study by researchers concluded that the combination of abdominal fat and muscle loss increases the risk of death by 83%, compared to people without these conditions.

This combination is so dangerous that it identifies an even greater problem: sarcopenic obesity. This condition is characterized by loss of muscle mass while gaining fat throughout the body. It is a difficult condition to diagnose, and it is related to loss of autonomy and a worsening quality of life in older adults. It is also known as frailty syndrome and is associated with an increased risk of falls and other comorbidities.

Valdete Regina Guandalini et al, Can simple measures from clinical practice serve as a proxy for sarcopenic obesity and identify mortality risk?, Aging Clinical and Experimental Research (2024). DOI: 10.1007/s40520-024-02866-9

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:36am

Fat tissue around the heart may contribute to greater heart injury after a heart attack 

Greater epicardial adipose tissue (EAT) volume, measured by cardiovascular imaging, is independently associated with larger myocardial infarct size and greater area at risk after myocardial infarction, though not with reduced left ventricular ejection fraction. Non-invasive EAT quantification may enhance cardiovascular risk assessment beyond traditional factors.

Epicardial adipose tissue (EAT) is the layer of fat between the myocardium and the lining of the heart, directly surrounding the coronary arteries. Under certain pathological conditions, EAT releases inflammatory mediators leading to myocardial infiltration and constrictive effects. Over time, adverse remodeling of the myocardium can occur.

Researchers have now shown that patients with increased EAT volume exhibited greater acute myocardial injury following MI.

https://www.escardio.org/The-ESC/Press-Office/Press-releases/fat-ti...

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:36am

'Self-activation' is part of the success strategy of parasitic weeds 

Certain parasitic weeds can autonomously activate their feeding organs (haustoria) before encountering a host by producing and releasing specific substances from their seeds. This early self-activation enables rapid and effective host attachment, contributing to their persistence and difficulty of control in agriculture. The process is influenced by compounds from both host and non-host seeds, and targeting these early signaling pathways may offer new weed management strategies.

Guillaume Brun et al, Seed metabolites headstart haustoriogenesis and potentiate aggressiveness of parasitic weeds, Science Advances (2025). DOI: 10.1126/sciadv.aea1449

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:33am

ATI2341 also protected mice from several other types of neutrophil-induced tissue damage but, crucially, did not impair the animals' ability to fend off bacterial and fungal infections.

Aroca-Crevillén et al. A circadian checkpoint relocates neutrophils to minimize injury, Journal of Experimental Medicine (2025). DOI: 10.1084/jem.20250240

Part2

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:32am

Switching immune cells to 'night mode' could limit damage after a heart attack

Researchers have identified a way to suppress the daily fluctuations in the activity of key immune cells known as neutrophils.

The study, published in the Journal of Experimental Medicine (JEM), suggests that inhibiting these fluctuations could prevent neutrophils from causing excessive tissue damage during daylight hours, a phenomenon that may underlie the fact that heart attacks in the early morning are more damaging than heart attacks suffered at night.

Neutrophils provide the first line of defense against microbial infections and tissue injury. However, their efforts to promote inflammation and kill injured or infected cells can result in the death of nearby healthy cells. In fact, neutrophils have an internal clock that makes them more active and prone to cause tissue damage during the daytime.

This could help explain the long-standing observation that heart attacks in the early morning have more severe consequences than heart attacks at night, because excessive neutrophil activity contributes significantly to the size of myocardial infarcts and long-term reductions in cardiac function.

So scientists realized that targeting the neutrophil clock could provide a simple and effective means to blunt the toxic activity of these cells during myocardial infarctions, without compromising antimicrobial defense.

They performed a series of experiments to confirm that, like in humans, mice suffer greater cardiac tissue damage after a heart attack in the early morning, and that this is due to enhanced neutrophil activity at this time of the day.

Treating mice with a drug that inhabits the neutrophil clock reduced the amount of myocardial tissue damage after a heart attack and helped to preserve heart function over the following days and weeks.

The drug, known as ATI2341, targets a receptor protein on the surface of neutrophils and switches the cells into a less active mode usually only seen at night.

In their active, daytime mode, neutrophils accumulate around the edge of the initial wound caused by a heart attack, where they are poised to damage neighboring healthy cardiac tissue and extend the size of the injury. In night mode, however, neutrophils accumulate in the center of the initial wound, well away from the surrounding, healthy tissue.

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