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Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:12am

New study finds 40% of cancer cases and almost half of all deaths  linked to modifiable risk factors

A study led by researchers at the American Cancer Society (ACS) finds four in 10 cancer cases and about one-half of all cancer deaths in adults 30 years old and older could be attributed to modifiable risk factors, including cigarette smoking, excess body weight, alcohol consumption, physical inactivity, diet, and infections.

Cigarette smoking was by far the leading risk factor, contributing to nearly 20% of all cancer cases and 30% of all cancer deaths. The findings are published in the journal CA: A Cancer Journal for Clinicians.

The risk factors included cigarette smoking (current and former smoking); secondhand smoke; excess body weight; alcohol consumption; consumption of red and processed meat; low consumption of fruits and vegetables, dietary fiber, and dietary calcium; physical inactivity; ultraviolet (UV) radiation; and infection with Epstein-Barr virus (EBV), Helicobacter pylori, hepatitis B virus (HBV), hepatitis C virus (HCV), human herpes virus-8 (HHV-8; also called Kaposi sarcoma herpesvirus), human immunodeficiency virus (HIV), and human papillomavirus (HPV). 

CA: A Cancer Journal for Clinicians (2024)

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:01am

These new results reveal a mystery. In the largest animals, there is something preventing brains from getting too big. Whether this is because big brains beyond a certain size are simply too costly to maintain remains to be seen. But as we also observe similar curvature in birds, the pattern seems to be a general phenomenon—what causes this 'curious ceiling' applies to animals with very different biology.

Chris Venditti et al, Co-evolutionary dynamics of mammalian brain and body size, Nature Ecology & Evolution (2024). DOI: 10.1038/s41559-024-02451-3

Part 2

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:00am

Brain size riddle solved as humans exceed evolutionary trend

The largest animals do not have proportionally bigger brains—with humans bucking this trend—a study published in Nature Ecology & Evolution has revealed.

Researchers collected an enormous dataset of brain and body sizes from around 1,500 species to clarify centuries of controversy surrounding brain size evolution.

Bigger brains relative to body size are linked to intelligence, sociality, and behavioral complexity—with humans having evolved exceptionally large brains. The new research reveals the largest animals do not have proportionally bigger brains, challenging long-held beliefs about brain evolution.

For more than a century, scientists have assumed that this relationship was linear—meaning that brain size gets proportionally bigger, the larger an animal is. We now know this is not true. The relationship between brain and body size is a curve, essentially meaning very large animals have smaller brains than expected.

The research reveals a simple association between brain and body size across all mammals which allowed the researchers to identify the rule-breakers—species which challenge the norm.

Among these outliers includes our own species, Homo sapiens, which has evolved more than 20 times faster than all other mammal species, resulting in the massive brains that characterize humanity today. But humans are not the only species to buck this trend.

All groups of mammals demonstrated rapid bursts of change—both towards smaller and larger brain sizes. For example, bats very rapidly reduced their brain size when they first arose, but then showed very slow rates of change in relative brain size, suggesting there may be evolutionary constraints related to the demands of flight.

There are three groups of animals that showed the most pronounced rapid change in brain size: primates, rodents, and carnivores. In these three groups, there is a tendency for relative brain size to increase in time (the "Marsh-Lartet rule"*). This is not a trend universal across all mammals, as previously thought.

* a tendency for relative brain sizes to increase with time. But, as the study notes, this rule is not universally applicable across all mammals
part 1

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 11:41am

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 11:28am

First fossil chromosomes discovered
Scientists have discovered intact chromosomes preserved in the skin of a woolly mammoth (Mammuthus primigenius) that met its end some 50,000 years ago — a feat previously thought to be impossible. The team also revealed the spatial organization of the mammoth’s DNA molecules and the active genes in its skin, including one responsible for giving the animal its fuzzy appearance. The study is the first to report the 3D structure of an ancient genome.

https://www.cell.com/cell/fulltext/S0092-8674(24)00642-1?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867424006421%3Fshowall%3Dtrue

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 10:48am

The study pinpoints potential targets for preventing or treating muscle weakness related to brain inflammation. The researchers found that IL-6 activates what is called the JAK-STAT pathway in muscle, and this is what causes the reduced energy production of mitochondria.
Several therapeutics already approved by the FDA for other diseases can block this pathway. JAK inhibitors as well as several monoclonal antibodies against IL-6 are approved to treat various types of arthritis and manage other inflammatory conditions.

The researchers are not sure why the brain produces a protein signal that is so damaging to muscle function across so many different disease categories, though.
They speculate about possible reasons this process has stayed with us over the course of human evolution, despite the damage it does, it could be a way for the brain to reallocate resources to itself as it fights off disease. More research is  needed  to better understand this process and its consequences throughout the body.

Shuo Yang et al, Infection and chronic disease activate a systemic brain-muscle signaling axis, Science Immunology (2024). DOI: 10.1126/sciimmunol.adm7908. www.science.org/doi/10.1126/sciimmunol.adm7908

Part 2

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 10:45am

Scientists identify possible way to block muscle fatigue in long COVID, other diseases

Infections and neurodegenerative diseases cause inflammation in the brain. But for unknown reasons, patients with brain inflammation often develop muscle problems that seem to be independent of the central nervous system. Now, researchers  have revealed how brain inflammation releases a specific protein that travels from the brain to the muscles and causes a loss of muscle function.

The study, in fruit flies and mice, also identified ways to block this process, which could have implications for treating or preventing the muscle wasting sometimes associated with inflammatory diseases including bacterial infections, Alzheimer's disease and long COVID.

The study is published July 12 in the journal Science Immunology.

 The study suggests that when we get sick, messenger proteins from the brain travel through the bloodstream and reduce energy levels in skeletal muscle. This is more than a lack of motivation to move because we don't feel well. These processes reduce energy levels in skeletal muscle, decreasing the capacity to move and function normally.

To investigate the effects of brain inflammation on muscle function, the researchers modeled three different types of diseases—an E. coli bacterial infection, a SARS-CoV-2 viral infection and Alzheimer's.

When the brain is exposed to inflammatory proteins characteristic of these diseases, damaging chemicals called reactive oxygen species build up. The reactive oxygen species cause brain cells to produce an immune-related molecule called interleukin-6 (IL-6), which travels throughout the body via the bloodstream.

The researchers found that IL-6 in mice—and the corresponding protein in fruit flies—reduced energy production in muscles' mitochondria, the energy factories of cells.

Flies and mice that had COVID-associated proteins in the brain showed reduced motor function—the flies didn't climb as well as they should have, and the mice didn't run as well or as much as control mice.

The researchers saw similar effects on muscle function when the brain was exposed to bacterial-associated proteins and the Alzheimer's protein amyloid beta. They also saw evidence that this effect can become chronic. Even if an infection is cleared quickly, the reduced muscle performance remains many days longer in their experiments.

The bacterial brain infection meningitis is known to increase IL-6 levels and can be associated with muscle issues in some patients, for instance. Among COVID-19 patients, inflammatory SARS-CoV-2 proteins have been found in the brain during autopsy, and many long COVID patients report extreme fatigue and muscle weakness even long after the initial infection has cleared.

Patients with Alzheimer's disease also show increased levels of IL-6 in the blood as well as muscle weakness.

Part1

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 10:03am

How galaxies avoid early death

Galaxies avoid an early death because they have a "heart and lungs" which effectively regulate their "breathing" and prevent them from growing out of control, a new study suggests.

If they didn't, the universe would have aged much faster than it has and all we would see today is huge "zombie" galaxies teeming with dead and dying stars.

That's according to a new study published in the Monthly Notices of the Royal Astronomical Society, which investigates one of the great mysteries of the universe—why galaxies are not as large as astronomers would expect.

Something appears to be stifling their enormous potential by limiting the amount of gas they absorb to convert into stars, meaning that instead of endlessly growing, something inside resists what was thought to be the inevitable pull of gravity.

Now, astrophysicists  think they may have uncovered the secret. They suggest that galaxies could in fact control the rate at which they grow through how they "breathe."

In their analogy, the researchers compared the supermassive black hole at the center of a galaxy to its heart, and the two bi-polar supersonic jets of gas and radiation they emit to airways feeding a pair of lungs.

Pulses from the black hole—or "heart"—can lead to jet shock fronts oscillating back and forth along both jet axes, much like the thoracic diaphragm in the human body moves up and down inside a chest cavity to inflate and deflate both lungs.

This can result in jet energy being transmitted widely into the surrounding medium, just as we breathe out warm air, resulting in slowing galaxy gas-accretion and growth.

The phenomenon is similar to the terrestrial equivalent of sound and shock waves being produced when opening a bottle of champagne, the screech of a car, rocket exhausts and the puncture of pressurized enclosures.

These supersonic jets might help in inhibiting galaxy growth.

The researchers concluded that a galaxy's lifespan can be extended with the help of its "heart and lungs," where the supermassive black hole engine at its core helps inhibit growth by limiting the amount of gas collapsing into stars from an early stage. This, the researchers say, has helped create the galaxies we see today.

Without such a mechanism, galaxies would have exhausted their fuel by now and fizzled out, as some do in the form of "red and dead" or "zombie" galaxies.

Carl Richards et al, Simulations of Pulsed Over-Pressure Jets: Formation of Bellows and Ripples in Galactic Environments, Monthly Notices of the Royal Astronomical Society (2024). DOI: 10.1093/mnras/stae1498

Comment by Dr. Krishna Kumari Challa on July 12, 2024 at 11:20am

Monkey malaria is infecting people

Malaysia was on the brink of eliminating malaria – then a new parasite swung out of the jungle

A new malaria parasite comes from monkeys. With thousands already infected, experts fear it could one day spread between humans.

Malaria has been eliminated in Malaysia, but another variety is spilling out from the rainforest and infecting people: monkey malaria. Around 25,000 people have been infected with the Plasmodium knowlesi parasite since 2011, which causes nausea, fever and sometimes death. Deforestation has driven a spike in cases, pushing monkeys, mosquitoes and people into closer proximity. The disease isn’t limited to southeast Asia, and as it spreads so too does the chance that monkey malaria will adapt to be spread between humans.

https://www.telegraph.co.uk/global-health/science-and-disease/monke...

Comment by Dr. Krishna Kumari Challa on July 12, 2024 at 10:58am

Muscle fibers are composed of many components, such as various proteins, cell nuclei, organelles such as mitochondria, and molecular motors such as myosin that convert chemical fuel into motion and drive muscle contraction.
All of these components form a porous network that is bathed in water. So an appropriate, coarse-grained description for muscle is that of an active sponge, say the researchers.
But the squeezing process takes time to move water around, so the researchers suspected that this movement of water through the muscle fiber set an upper limit on how rapidly a muscle fiber can twitch.

To test their theory, they modeled muscle movements in multiple organisms across mammals, insects, birds, fish and reptiles, focusing on animals that use muscles for very fast motions. They found that muscles that produce sound, such as the rattle in a rattlesnake's tail, that can contract ten to hundreds of times per second typically don't rely on fluid flows. Instead, these contractions are controlled by the nervous system and are more strongly dictated by molecular properties, or the time it takes for molecular motors within cells to bind and generate forces.
But in smaller organisms, such as flying insects who are beating their wings a few hundred to a thousand times per second, these contractions are too fast for neurons to directly control. Here fluid flows are more important.
In these cases, the researchers found that fluid flows within the muscle fiber are important and their mechanism of active hydraulics is likely to limit the fastest rates of contraction.
The researchers also found that when muscle fibers act as an active sponge, the process also causes the muscles to act as an active elastic engine. When something is elastic, such as a rubber band, it stores energy as it tries to resist deformation. Imagine holding a rubber band between two fingers and pulling it back.

When you release the rubber band, the band also releases the energy stored when it was being stretched. In this case, energy is conserved—a basic law of physics that dictates that the amount of energy within a closed system should remain the same over time.
But when muscle converts chemical fuel into mechanical work, it can produce energy like an engine, violating the law of the conservation of energy. In this case, muscle shows a new property called "odd elasticity," where its response when squashed in one direction versus another is not mutual.

Unlike the rubber band, when muscle contracts and relaxes along its length, it also bulges out perpendicularly, and its energy does not stay the same. This allows muscle fibers to generate power from repetitive deformations, behaving as a soft engine.

These results are in contrast to prevailing thought, which focuses on molecular details and neglects the fact that muscles are long and filamentous, are hydrated, and have processes on multiple scales.
All together, our results suggest a revised view of how muscle functions is essential to understand its physiology. This is also crucial to understanding the origins, extent and limits that underlie the diverse forms of animal movement.

Suraj Shankar et al, Active hydraulics and odd elasticity of muscle fibres, Nature Physics (2024). DOI: 10.1038/s41567-024-02540-x

Part 2

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