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Comment by Dr. Krishna Kumari Challa 5 hours ago

Urban heat islands linked to worse recovery after major surgery

Patients living in areas with more intense urban heat were less likely to have an optimal recovery after major surgery, according to new research on nearly 700,000 patients.
Among 697,552 patients undergoing major surgery, greater neighbourhood heat was associated with worse recovery. Above a heat-island intensity of 2.19°C, each additional 1°C was associated with 8% higher odds of not achieving an optimal outcome.
Above an urban heat island intensity threshold of 2.19°C, or about 3.9°F, each additional 1°C (1.8°F) was associated with 8% higher odds of not achieving a "textbook outcome." In this study, a textbook outcome required no complications, no readmission, no prolonged hospital stay and survival for at least 30 days.

An urban heat island is a developed area that is warmer than its surroundings. Roads, buildings and other infrastructure absorb and re-emit more heat than natural landscapes, while limited trees and vegetation reduce shade and natural cooling. The temperature difference can vary substantially across neighbourhoods within the same city.
Heat isn't only uncomfortable; these data suggest it can have a real impact on surgical recovery.
Overall, 50.2% of patients achieved a textbook outcome. Across the cohort:

25.2% experienced complications
22.9% had a prolonged hospital stay
14.8% were readmitted
7.1% died within 30 days

The findings suggest that surgical teams may need to consider not only whether a patient is medically ready to leave the hospital, but also whether the patient can recover safely in the environment to which they are returning.

"Do you have air conditioning in your house? Do you have a fan? Are you going to be able to stay hydrated?," Doctors should be asking these questions, say the researchers . They add that questions about heat exposure may need to be increasingly incorporated into discharge planning.
People at higher risk during extreme heat include older adults, people with chronic health conditions or disabilities, people with limited incomes, people experiencing homelessness and those who do not have access to safe, adequately cooled housing.
Because the study was observational, it identifies an association and does not establish that residential heat exposure caused the worse outcomes.

Wang, J, et al. Heat Island-Related Surgical Outcome Burden under Global Warming, Demographic and Adaptation in 3,144 Counties across the United States. Scientific Forum, American College of Surgeons (ACS) Clinical Congress 2026. 

Comment by Dr. Krishna Kumari Challa 5 hours ago

The brain begins learning in utero
In addition to showing yet again that smoking during pregnancy is harmful to the fetus, this study confirms that experience and environment shape the brain long before birth.

A young child who hears speech, observes their surroundings and experiments with new movements literally transforms their brain through those experiences.
The spontaneous waves produced by the retina constitute a form of 'internal experience' for the fetus. They give the visual system activity that supports its own development, even before the baby starts looking at the world.

To understand how the human brain develops, then, we must look not only at genes and what happens after birth, but also at the very first experiences, which occur before the fetus has access to the outside world.

Xavier Navarri et al, The tangential growth of the human visual cortex and maternal smoking during pregnancy, Cerebral Cortex (2026). DOI: 10.1093/cercor/bhag105

part2

Comment by Dr. Krishna Kumari Challa 6 hours ago

Smoking during pregnancy linked to smaller visual cortex

We tend to think of a fetus's brain as a construction site guided by a blueprint imprinted in the genes. But even before birth, other things are happening. The fetus moves, responds to muffled sounds, receives stimuli and, crucially, its own nervous system is already generating activity.
A recent study sheds new light on this prenatal activity. One important finding is that signals spontaneously generated by the retina may help shape the primary visual cortex, the brain region that processes visual information
The retina, at the back of the eye, contains cells specialized for receiving light. But even before a baby can actually see, these cells spontaneously produce waves of activity. These waves travel through the visual system and reach the cortex.

Animal studies had already shown that if this activity is blocked, the development of the visual cortex is disrupted. So the brain doesn't necessarily wait for external images to arrive before it starts developing. Before that, it already receives a kind of 'stimulation' produced from within.

This is where nicotine enters the picture.
The waves of spontaneous activity in the retina rely on acetylcholine, a neurotransmitter whose signalling is disrupted by nicotine. Researchers hypothesized that nicotine exposure could alter these waves and therefore influence the development of the primary visual cortex.

They tested this hypothesis using causal variants to investigate whether nicotine exposure was the cause, rather than merely correlated with the difference. The results confirmed the hypothesis.
Does a smaller cortex mean poorer vision?
The primary visual cortex is like a TV screen. The larger its surface area, the more pixels—that is to say, neurons—it can potentially contain, allowing for more detailed representation of visual information.
A direct link between V1 surface area and visual resolution has been observed in animals, but not as directly in humans.

However, in the British biobank data, the team did find that a larger primary visual cortex was associated with abilities that suggest better shape perception.
Part 1

Comment by Dr. Krishna Kumari Challa yesterday

 Why your day isn't quite 24 hours?

You might think the length of a day never varies—exactly 24 hours. You'd be wrong, at least if you count days in milliseconds, as physicists do.

Earth’s day length varies by milliseconds over decades as the core and mantle exchange angular momentum. Changes in the solid inner core’s rotation exert gravitational torque on the mantle, while friction and electromagnetic drag at the core–mantle boundary oppose it. The balance between these torques explains the observed variations.
For about 30 years, scientists have known that the rotation of Earth's liquid core—detected through changes in its magnetic field—speeds up over a few decades, then slows down over a few more.

Meanwhile, the mantle—the rocky shell that includes the crust and is 3,000 kilometers (1,860 miles) thick—slows down, then speeds up to compensate, because the planet's angular momentum must remain constant.

That change in the mantle's rotational speed can shorten or lengthen a day by a few milliseconds over time.
But in a new study published in Nature, researchers show that small changes in the rotational speed of the inner core—the solid, central part of the core, which is not exactly spherical—exert what's called a "gravitational torque" on mass anomalies within the mantle, causing a slight fluctuation in the length of a day.

Another form of torque at the boundary of the core and mantle creates friction and electromagnetic drag—called core-mantle boundary torque—that resist the gravitational tug and limit changes in the length of a day. Subtle shifts in the balance between gravitational and core-mantle torque are ultimately responsible for the small changes observed in the length of a day.

Huifeng Zhang et al, Gravitational torque drives multidecadal variations in length of day, Nature (2026). DOI: 10.1038/s41586-026-10999-2

Comment by Dr. Krishna Kumari Challa yesterday

For the mice, the DCTAL routine included compressive forces ranging from 0.5 N to 4 N, delivering 300 cycles per day. In pigs, the force was scaled up to twice their body weight, with 400 cycles per day.
For pigs suffering severe head trauma, DCTAL extended median survival by five days, giving them crucial extra time to recover. The same treatment also improved movement in mice after TBI or stroke. In pole mobility tests, DCTAL-treated mice initiated movement sooner and descended faster, with significant improvements at one week and eight weeks after injury.

When DCTAL was administered before or shortly after a stroke, motor deficits were reduced by more than 50%. In maze navigation tests, treated mice showed a striking recovery, with memory performance improving nearly fivefold and the ability to stay within the target area rising by 62.2% just one week after injury. DCTAL also helped protect brain tissue while promoting regeneration. The number of immature neurons increased 4.5-fold, while neural stem cell populations rose nearly sixfold.

Leg bones are packed with osteocytes, cells that sense mechanical force through a protein called PIEZO1, which acts like an on switch for brain healing. When physical force activates PIEZO1, it prompts osteocytes to release a mix of protective signaling proteins directly into the bloodstream, much like endocrine cells do. When researchers removed PIEZO1 from these cells, the healing effects vanished entirely, showing that it is the essential trigger.

This study shows that the bone-brain axis works both ways: mechanical force on bone can tune its hormone-releasing function to boost brain repair after injury. If confirmed in clinical trials, a simple device that gently compresses the shinbone could become a rehabilitation tool for patients unable to exercise on their own.

Zhiqing Cai et al, Tibial bone compression promotes recovery after brain injury through osteocyte PIEZO1, Nature Neuroscience (2026). DOI: 10.1038/s41593-026-02422-w

Part 2

Comment by Dr. Krishna Kumari Challa yesterday

Gentle rhythmic tapping on shinbone helps injured brains heal faster in animal models

A traumatic brain injury (TBI) can turn a person's life upside down, leaving lasting effects on memory, thinking, physical abilities and overall quality of life. TBI remains one of the leading causes of death and disability worldwide. Yet, paradoxically, the same injury that harms the brain may sometimes appear to benefit a broken bone by speeding up healing. In a recent study published in Nature Neuroscience, researchers explored whether the reverse is true.
To test whether bones could influence recovery after brain injury, the researchers induced TBI and stroke in mice and pigs. Then, using a small biomechanical device, they applied gentle, rhythmic compression to the animals' shinbones (tibias) for five days. This technique is called dynamic compressive tibial axial loading (DCTAL).

The results revealed a direct bone–brain axis. Applying mechanical pressure to the leg bones helped the brain heal after stroke and TBI while also improving movement and memory. In mice with TBI, DCTAL reduced brain cell loss, eased chronic inflammation and promoted the growth of new neurons. In severe brain injury models, bone compression also had a striking effect on survival, raising 14-day survival rates from 20% to 90%.
The effects of TBI or a stroke often unfold in waves. The immediate injury can affect thinking, movement and emotional well-being, while secondary damage can cause a gradual loss of brain cells over hours, days or even months. These effects, however, trigger a healing response in the skeletal system.

Doctors have long observed that when patients suffer a TBI alongside a broken bone, their fractures heal significantly faster, with bone calluses forming much more rapidly than normal. When the brain is injured, damaged brain cells release microscopic, fluid-filled bubbles into the blood. The bubbles travel to the skeleton, where they attach to young bone stem cells called osteoprogenitors and prompt them to multiply and build new bone tissue.

For decades, researchers have searched for a drug that could restore lost brain function or repair damaged tissue after stroke or traumatic brain injury, with little success. The nondrug treatments available today ease some effects of brain injury without reversing the damage. This pushed researchers to think differently, aiming for a treatment that could trigger a broad healing response across the whole body.

That search led the researchers to the bone-brain connection. They wanted to find out whether healing signals from bone could drive recovery in the brain. To test this, the team placed anesthetized animals (pigs and mice) with simulated TBI and stroke into specialized ElectroForce biomechanical loading devices fitted with custom leg clamps. The animals then received gentle, repeated pressure down their tibias five days per week at a rhythm of two pushes per second (2 Hz).
Part 1

Comment by Dr. Krishna Kumari Challa on Thursday

Every extra 100 grams of ultra-processed food linked to higher disease risks

Higher ultra-processed food (UPF) intake is linked to a heightened risk of several major chronic health issues, such as digestive diseases, high blood pressure and metabolic syndrome/diabetes, as well as death, finds a pooled data analysis of the available evidence published in the open-access journal Family Medicine and Community Health.
Pooled prospective cohort data from 8.8 million adults linked higher ultra-processed food intake with increased risks of cardiovascular disease, cancer, obesity, metabolic disorders, digestive disease, hypertension, mental health conditions, and all-cause mortality. Each additional 100 g/day was associated with higher cardiovascular, cancer, mortality, and metabolic risk, though residual lifestyle confounding remains possible.
Every additional 100 g (3.5 ounces) consumed was associated with correspondingly greater risks, the analysis indicates.

Ultra-processed foods are defined as ready-to-eat or heat-and-serve products that have undergone extensive industrial processing. Typically, they contain a range of additives, are energy-dense and high in sugar and salt but low in dietary fiber, protein, vitamins and minerals, the researchers explain.

Pooled data analysis of the results of the included studies showed that higher UPF consumption was associated with greater risks of multiple chronic health issues and death from any cause, with risks rising in tandem with the quantity consumed.

High consumption of ultra-processed foods was associated with higher risks of cardiovascular events (24%), cancer (12%), obesity/overweight (23%), metabolic syndrome/diabetes (24%), depression/anxiety (27%), digestive diseases (31%), high blood pressure (11%) and death from any cause (18%).

Further analyses showed that each additional 100 g/day (3.5 ounces per day) consumed was associated with greater risks of cardiovascular events (14%), cancer (4%), death from any cause (3%) and metabolic syndrome/diabetes (2%).

And every 10% increase in weight/energy intake was associated with a 16% greater risk of metabolic syndrome/diabetes.
Emerging evidence suggests that the combination of multiple additives may exert a "cocktail effect" on human health, while laboratory studies have shown that the extensively altered physical composition of UPFs may adversely affect the gut microbiome and promote inflammation and insulin resistance, among other effects, the researchers point out.

Several compounds that may form during food processing, such as acrylamide—a contaminant formed in heat-treated processed foods—and acrolein, generated during fat heating, have been associated with a higher incidence of cardiovascular disease, they add.

Ultra-processed food consumption and risk of multiple chronic diseases among 8,819,894 adults from 51 prospective cohorts: a dose- response meta- analysis, Family Medicine and Community Health (2026). DOI: 10.1136/fmch-2026-003925

Comment by Dr. Krishna Kumari Challa on Thursday

But some factors can prevent an echo chamber. For example, individuals at a group's periphery may be connected to those at the centre, but they are also influenced by others and can pick up information from their environment, triggering change throughout the group.

It's really the free spirits, the individuals who have stayed at the edge and don't have many social influences, who are the first ones to change. They can set off a cascade.

Another factor that prevents echo chambers comes from individuals who recognize that their decisions are wrong and start ignoring the group.

If some of the individuals in the network, even just a small fraction of them, do that some of the time, it will destroy an echo chamber.

Ling-Wei Kong et al, Messaging strategies and the emergence of echo chambers in collective decision-making, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2613908123

Comment by Dr. Krishna Kumari Challa on Thursday

How biological echo chambers form—and what can break them

Tropical army ants are known to form devastating armadas that march through forests eating other insects and small creatures. As they march, they deposit chemical trails of pheromones that others behind them sense and follow. But occasionally one of these ants will walk in a circle, prompting a subset of ants behind them to follow until they all collapse and die.

They end up in this cycle where they're reinforcing the same pattern over and over again. This is a physical instance of an echo chamber, where the animals involved actually die.
A new study examines how a few general constraints can lead to echo chambers—self-reinforcing feedback loops—in groups of biological agents such as birds in a flock, cells in tissue or ants in a swarm, and explores ways to control them.

The paper, published Sept. 22 in the Proceedings of the National Academy of Sciences, uses mathematical models to test parameters that increase and decrease the likelihood of an echo chamber forming.

In humans, the phenomenon occurs in groups when individuals send and receive similar messages and lack external sources of differing information. Many biological systems in which individuals collectively make decisions—such as fish in a school darting away from a suspected predator—face two key constraints, according to the paper.

First, an individual often observes only a neighbor's discrete actions and doesn't know all the internal information that led that neighbor to behave in a certain way. Second, individuals have limited attention at any moment and can attend to the actions of only a few neighbours, rather than many of them at once.

The study reveals that these constraints can make individuals extremely sensitive to messages they receive from others and encourage them to send and receive similar messages back and forth, creating an echo chamber.

It happens when people are telling each other the same thing, but there's also an implication that this group has become unresponsive to what's actually happening in the world around them.
In the study, the researchers also started with computer models previously studied by other researchers in which agents in a network shared the actual data that caused them to form a particular opinion or take a particular action.

It's as if one person expresses his opinion to another person, but instead of telling him what his opinion is, he tells him everything that he ever learned that caused him to form that opinion.

The model also assumed that any agent in the network could pay attention to all of its neighbours at once. With these two assumptions in place, the models did not form echo chambers.
This means individuals rarely have all the information that led to an action or opinion, nor can they pay attention to many things at once.
The researchers then tinkered with these assumptions, removing one or both to create more realistic constraints. The behaviour of the group of agents as a whole could become just totally dysfunctional and the form that this dysfunction takes is really an echo chamber.
Individuals can reach a consensus decision but it becomes totally decoupled from the state of the world around them.
Part 1

Comment by Dr. Krishna Kumari Challa on Thursday

Uncovering gravity's impact on the human genome
After 24 hours of simulated microgravity, human cells had larger nuclei, but genome organization and motion remained stable, with no detectable DNA damage. Fluid flows altered cell shape and caused DNA damage, underscoring the need to control for flow in microgravity experiments.

More specifically, the researchers investigated changes in the genome's organization, dynamics and possible DNA damage induced by simulated microgravity. Overall, the results showed the following:

The cells' shape became elongated when exposed to flows but remained unchanged when exposed to simulated microgravity.

The volume of the cell nucleus increased after exposure to zero gravity, indicating that gravity diminishes it.

Despite the changes to the nucleus's shape and volume under zero gravity, the thickness and structure of the nuclear envelope remained unchanged, suggesting gravity has minimal impact on these traits.

The genome inside the cell nucleus maintained its physiological organization and motions after 24 hours of exposure. T

he researchers showed that simulated microgravity does not cause DNA damage; however, DNA damage occurs when cells are exposed to flows. The nucleolus became smoother after exposure to simulated microgravity or flows.

Overall, a daylong exposure of the nucleus to simulated microgravity led to rather subtle changes, which, the researchers add, could amplify over time and then affect cell physiology.

Nikitas Kanellakopoulos et al, The Effect of Microgravity and Flows on the Organization and Dynamics of the Human Genome, Science Advances (2026). DOI: 10.1126/sciadv.aeh3116. www.science.org/doi/10.1126/sciadv.aeh3116

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