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Comment by Dr. Krishna Kumari Challa on February 22, 2025 at 12:01pm

Breathing and vision may be linked

Researchers  have discovered a fundamental mechanism that affects the size of the pupil, namely our breathing. The study, published in the Journal of Physiology, shows that the pupil is smallest during inhalation and largest during exhalation—something that could affect our vision.

Like the aperture in a camera, the pupil controls how much light reaches the eye. It is therefore fundamental to our vision and how we perceive our surroundings. Three mechanisms that can change the size of the pupil have been known for over a century: the amount of light, focus distance and cognitive factors such as emotion or mental effort.

Now, scientists have discovered a fourth: breathing. The pupil is smallest around inhalation onset and largest during exhalation.

This mechanism is unique in that it is cyclical, ever-present and requires no external stimulus

Martin Schaefer et al, The pupillary respiratory‐phase response: pupil size is smallest around inhalation onset and largest during exhalation, The Journal of Physiology (2025). DOI: 10.1113/JP287205

Comment by Dr. Krishna Kumari Challa on February 22, 2025 at 11:35am

To show how this works, the researchers placed genetically identical Escherichia coli bacteria—which exhibit different swimming behaviors—in both liquid and porous environments and then observed their collective migration.

In the liquid environment, which the researchers compared to a straight highway, bacteria that swam straight for longer took the lead while those that turned frequently lagged behind. Over time, the population of these bacteria became enriched with these smooth swimmers.

On the other hand, in porous environments with more obstructions, the tendency to turn frequently proved advantageous for escaping dead ends. In these environments, the bacteria that turned more often emerged as the leaders while populations of smooth swimmers gradually thinned.
Crucially, the enrichment of specific swimming behaviors could not be explained by mutations or gene expression. The researchers found no evidence of an increase or decrease in the expression of genes regulating the swimming behaviors of these bacteria during migration.

Since there were no changes in gene expression or mutations, the populations didn't commit to one environment or another—migration alone was enough to temporarily enrich the population with well-adapted individuals.

Non-genetic adaptation via collective migration not only permits a rapid response to new environments, but also enables cell populations to respond to many biological challenges simultaneously.
While gene regulation typically allows for a quick reaction by modifying one or two traits at a time, the mechanism now discovered facilitates a rapid response by simultaneously altering many traits.
Beyond enabling populations to adapt to changes in the environment within two to three generations of cell division, this mechanism can also modulate chemoreceptor abundances depending on what attractants the bacteria are chasing, highlighting its potential flexibility, the researchers found.
This process is likely applicable to many cell types, both prokaryotic and eukaryotic, that break down environmental factors and generate their own gradient to chase, say the researchers.
These findings demonstrate that when collective behaviors create selection pressures, cell populations can reversibly adapt multiple traits with a level of speed and flexibility that is difficult to achieve via classical mechanisms.

Lam Vo et al, Nongenetic adaptation by collective migration, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2423774122

Part 2

Comment by Dr. Krishna Kumari Challa on February 22, 2025 at 11:32am

How do cells respond to changes? New study finds it's not all in the genes

Cells are constantly on the move, whether in a developing embryo or metastatic cancer. But how do cells adapt to the new environments they encounter? Earlier scientists thought that cells adapt to changes and stressors in their environment through genetic mutations or by altering gene expression.

But a new  study shows that migrating bacterial cells can also respond to changes in their surroundings, quickly and collectively, without any genetic alterations. Specifically, the researchers found that cell populations can adapt "non-genetically" to new environments just by growing and leaving behind slower cells.

This new discovery, which is described in the journal Proceedings of the National Academy of Sciences, has implications across biology, from advancing our understanding of evolution to informing new therapeutic strategies for diseases like cancer.

Given the prevalence of collective migration in microbes, cancers, and embryonic development, non-genetic adaptation through collective migration may be a universal mechanism for populations to navigate diverse environments. 

Past research has shown that bacterial cells can acquire genetic mutations that confer resistance in response to antibiotics. Similarly, cancer cells can develop resistance to chemotherapy through genetic changes. Yet such adaptations typically require tens of generations before the mutated cells become predominant. (In some bacterial cells , cell division or generation happens about every hour).

The new adaptive mechanism enables migrating cell populations to respond to environmental changes in just two or three generations and without relying on gene regulation or mutation.  

Part 1

Comment by Dr. Krishna Kumari Challa on February 21, 2025 at 12:29pm

The potential health effects of plastic pollution are only just beginning to emerge, but the mounting evidence is not exactly inspiring hope.

In a study published last year, scientists discovered that when people put hot, disposable plastic cutlery in their mouths, it reduces their diversity of intestinal microbiota.

The next time you order takeaway, you might want to think about the heat of the food and the material of the packaging it might come in.

https://www.sciencedirect.com/science/article/pii/S0147651324014593

Part 2

Comment by Dr. Krishna Kumari Challa on February 21, 2025 at 12:28pm

Your Takeaway Food Packaging Could Increase Your Risk of Heart Failure

Disposable plastic containers could be leaching dangerous chemicals into your takeaway food, potentially increasing your risk of cardiovascular disease.

In experiments on rats, researchers in China have found evidence that drinking water exposed to the various chemical additives that seep from heated plastic packaging causes changes to the body, that begin with altered gut bacteria.

Rodents that ingested this cocktail of plastic contaminants for just three months showed broken or misaligned fibers, inflammatory cell infiltration, and mitochondrial swelling in their heart tissue. They also showed bleeding between myocardial cells.

Whether or not the same occurs in the human body is unknown, but the findings suggest that heated plastic containers may not be a safe vehicle for food.

Researchers argue that it is essential to avoid using plastic containers for high-temperature food.

Their experiments on rats were prompted by a survey of 3,179 older adults in China. Those who reported higher exposure to plastic on a questionnaire were more likely to suffer congestive heart failure.

Heat causes plastic to break down more easily, but even bottled water, which is usually kept at room temperature or colder, seems to be swimming with microplastics.

Recently, studies have shown that microwaving plastic food containers can release microplastics and nanoplastics into the meal, even if the containers claim to be microwave-safe. As few as three minutes can release billions of tiny plastic particles.

How many of those plastic particles are absorbed into the body when ingested is unknown. It's also a mystery as to how long the fragments stick around for.

Some studies on clogged arteries in human patients have found tiny fragments of plastic accumulating in more than 50 percent of plaques. Within roughly 34 months of surgery, those with plastics in their arteries were 4.5 times more likely to have a heart attack, stroke, or death compared to those where no plastic was detected.

When the body is exposed to plastic contaminants, researchers suspect there's a chance the additives can reduce the activity of antioxidant enzymes and trigger the body's inflammatory reaction, leaving it exposed to cardiovascular damage.

Part 1

Comment by Dr. Krishna Kumari Challa on February 21, 2025 at 11:35am

It is crucial to carefully consider the subject's posture during [pulse wave velocity] measurements to accurately assess arterial stiffness," the researchers wrote in their paper.

 Marino Karaki et al, The validity of carotid-femoral pulse wave velocity in the seated posture as an index of central arterial stiffness, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology (2024). DOI: 10.1152/ajpregu.00073.2024

Part 2

Comment by Dr. Krishna Kumari Challa on February 21, 2025 at 11:34am

Vital sign accuracy may depend on body position, research suggests

Body position can affect the accuracy of vital sign measurements that indicate arterial stiffness—a risk factor for heart disease—according to new research. Sitting down during certain tests may cause a spike in arterial stiffness readings that does not reflect a true increase.

The study is published in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 

Arterial stiffness is when the walls of the blood vessels are not as elastic or stretchy as they should be. The condition is often a part of aging and can also occur in people who have diabetes, high cholesterol or high blood pressure. People with stiffer arteries have an increased risk of heart attack, stroke and other forms of heart disease.

Medical professionals most commonly measure markers of arterial stiffness with patients lying on their back (supine position). However, sitting may be a more practical option for people with chronic back pain or other health concerns.

In this study, researchers explored whether measuring carotid-femoral pulse wave velocity—the time it takes for the pulse to travel from the carotid to the femoral artery—can be considered reliable when measured in a seated position. Carotid-femoral pulse wave velocity (cfPWV) is considered the "gold standard" for measuring arterial stiffness.

The research team assessed a small group of young, healthy volunteers in both supine and seated positions on the same day. The researchers measured heart rate and blood pressure as well as cfPWV and took measurements three times in each position. They also analyzed the difference in arterial stiffness markers after a change from one position to the other.

Blood pressure, arterial pressure and heart rate were generally higher when participants were sitting compared to lying down. The researchers found cfPWV to be much higher when seated as well. However, when looking at blood flow and blood pressure between the two postures and adjusting the calculations to account for changes in hydrostatic pressure (pressure created due to gravity), the readings were much more comparable.
In addition, these findings suggest the activation of the sympathetic nervous system that occurs while sitting is not strong enough to cause large increases in arterial stiffness.

This study may have important implications for diagnosis of arterial stiffness and, in turn, the risk of heart disease.

Part 1

Comment by Dr. Krishna Kumari Challa on February 21, 2025 at 11:28am

Radon exposure linked to increased asthma symptoms in children

A radioactive gas could be contributing to asthma among schoolkids, researchers have found.

Children exposed to elevated levels of radon gas tended to have more asthma symptoms, results show.

Radon is a naturally occurring radioactive gas that's odorless and invisible, according to the U.S. Centers for Disease Control and Prevention (CDC). It emanates from the breakdown of trace amounts of uranium found in soil. Homes can fill with radon as it seeps out of soil and up through cracks and crevices, the CDC says. It is the second-leading cause of lung cancer deaths in some countries after cigarette smoke.

 Tina M. Banzon et al, Effect of radon exposure on asthma morbidity in the School Inner‐City Asthma study, Pediatric Pulmonology (2023). DOI: 10.1002/ppul.26429

Joyce E. Yu, Effect of Radon Exposure on Asthma Morbidity in the School Inner-City Asthma Study, Pediatrics (2024). DOI: 10.1542/peds.2024-069114KG

Comment by Dr. Krishna Kumari Challa on February 21, 2025 at 11:24am

Screen time linked to bipolar and manic symptoms in  preteens

Preteens who spend more time on screens are more likely to develop manic symptoms two-years later, according to a new study published in Social Psychiatry and Psychiatric Epidemiology.

The findings reveal that 10–11 year-olds who engage heavily with social media, video games, texting, and videos show a greater risk of symptoms such as inflated self-esteem, decreased need for sleep, distractibility, rapid speech, racing thoughts, and impulsivity—behaviors characteristic of manic episodes, a key feature of bipolar-spectrum disorders.

Adolescence is a particularly vulnerable time for the development of bipolar-spectrum disorders. Given that earlier onset of symptoms is linked with more severe and chronic outcomes, it's important to understand what might contribute to the onset or worsening of manic symptoms in teenagers.

Symptoms of social media and video game addiction, characterized by the inability to stop despite trying, withdrawal, tolerance, conflict, and relapse, may play a role. Screen addictions and irregular sleep patterns may exacerbate manic symptoms in susceptible teens.

The study adds to the wealth of knowledge on the associations between screen use and poor mental health in adolescents.

Jason M. Nagata et al, Screen time and manic symptoms in early adolescents: prospective findings from the Adolescent Brain Cognitive Development Study, Social Psychiatry and Psychiatric Epidemiology (2025). DOI: 10.1007/s00127-025-02814-6

Comment by Dr. Krishna Kumari Challa on February 21, 2025 at 11:19am

Experts strongly recommend against spine injections for chronic back pain

Spine injections should not be given to adults with chronic back pain because they provide little or no pain relief compared with sham injections, say a panel of international experts in The BMJ.

Their strong recommendations apply to procedures such as epidural steroid injections and nerve blocks for people living with chronic back pain (lasting at least three months) that is not associated with cancer, infection or inflammatory arthritis.

Their advice is based on the latest evidence and is part of The BMJ's "Rapid Recommendations" initiative—to produce rapid and trustworthy guidance based on new evidence to help doctors make better decisions with their patients.

Chronic back pain is the leading cause of disability worldwide. It is estimated to affect one in five adults aged 20–59, with higher rates likely among older adults.

Procedures such as epidural steroid injections, nerve blocks and radiofrequency ablation (using radio waves to destroy nerves) are widely used to stop pain signals reaching the brain, but current guidelines provide conflicting recommendations for their use.

So an international panel, made up of clinicians, people living with chronic spine pain, and research methodologists, carried out a detailed analysis of the latest evidence using the GRADE approach (a system used to assess the quality of evidence).

This evidence, based on reviews of randomized trials and observational studies, compared the benefits and harms of 13 common interventional procedures, or combinations of procedures, for chronic, non-cancer spine pain against sham procedures.

After careful consideration, the panel concluded that there was no high certainty evidence for any procedure or combination of procedures, and all low and moderate certainty evidence suggests no meaningful relief for either axial pain (in a specific area of the spine) or radicular pain (radiating from the spine to the arms or legs) for spine injections compared with sham procedures.

As such, they strongly recommend against their use.

This includes injections of local anesthetic, steroids, or their combination; epidural injections of local anesthetic, steroids, or their combination; and radiofrequency ablation with or without local anesthetic plus steroid injections. The panel added that these procedures are costly, a burden on patients, and carry a small risk of harm. As such, they say almost all informed patients would choose to avoid them.

Finally, they acknowledge that further research is warranted and may alter future recommendations, in particular for procedures currently supported by low or very low certainty of effectiveness. Further research is also needed to establish the effects of interventional procedures on important outcomes for patients, such as opioid use, return to work, and sleep quality.

Commonly used interventional procedures for non-cancer chronic spine pain: a clinical practice guideline, The BMJ (2025). DOI: 10.1136/bmj-2024-079970

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