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Comment by Dr. Krishna Kumari Challa 15 hours ago

Your gut can get jet lag too: How not to waste the first days of your vacation

A dream vacation, an exotic destination, a long-haul flight and finally some well-deserved rest. The problem is that many travelers arrive at their destination only to spend the first days of their vacation struggling with fatigue, sleep disturbances, low energy levels and digestive issues. Researchers point out that these symptoms may be caused by more than classic jet lag. A growing body of evidence suggests that time zone changes also affect the trillions of bacteria living in our intestines.

This phenomenon, known as "gut jet lag," describes a disruption in synchronization between the human biological clock and the rhythms of the gut microbiota. Although the concept is relatively new, researchers agree that our intestines may need just as much time as our brains to adapt to a new time zone.

Long-haul travel and rapid time zone shifts can desynchronize circadian rhythms of the gut–brain axis and microbiota, causing fatigue, sleep disturbances, and digestive symptoms (“gut jet lag”). Disrupted meal timing alters enzymes, bile, motility, and microbiome composition, reducing barrier integrity and short-chain fatty acid production. Gradual pre-trip adjustment of sleep–light cycles and meal times, daytime-aligned eating, hydration, and targeted probiotics may mitigate effects. Similar mechanisms affect shift workers and individuals with chronic circadian disruption.

Gut jet lag is a relatively new concept describing a state of desynchronization between the human biological cycle and the rhythms of gut bacteria. A short trip within Europe is unlikely to cause such major disruptions, but the problem becomes significant during long-haul flights that involve crossing multiple time zones.
Under these conditions, fatigue and dietary changes can compromise intestinal barrier integrity and reduce the production of beneficial short-chain fatty acids.
Intercontinental travel means much more for the body than simply changing the time on a watch. Within a matter of hours, sleep schedules, meal times, light exposure and stress levels all change dramatically. For the body, it is a major upheaval.

Our digestive system is extremely sensitive to these changes because the entire gut-brain axis operates according to a tightly regulated circadian rhythm. When biological signals become misaligned, communication between the intestines, immune system and brain is temporarily disrupted.
his temporary dysregulation is responsible for digestive complaints, poorer sleep quality and reduced energy levels in many people during the first days after arrival.
This helps explain why the first days of a vacation are often the least comfortable. While the body is trying to adapt to new environmental conditions, gut bacteria may still be operating according to the schedule of the departure location.

Part 1

Comment by Dr. Krishna Kumari Challa 16 hours ago

Earlier toilet training could curb growing diaper waste crisis

Earlier toilet training and new recycling technologies are among expert-backed solutions to reduce the environmental impact of disposable diapers and other hygiene products, according to a new study by researchers.
Absorbent hygiene products generate 160–200 million metric tons of waste annually, largely landfilled or incinerated, with additional pollution where waste systems are absent. The paper proposes three main interventions: earlier toilet training and reusable products to cut use, advanced recycling to recover all materials, and fully compostable designs, with region-specific strategies and policy changes needed for implementation.
The paper, published in Nature Sustainability, sets out a roadmap for changing how absorbent hygiene products (AHPs), which include diapers, incontinence products and period products, are designed, used and disposed of.

AHPs account for an estimated 160–200 million metric tons (176–220 million tons) of waste each year globally, with the vast majority sent to landfills or incineration. In regions without adequate waste collection, used diapers are often dumped or burned, contributing to plastic pollution, contaminated water and the spread of disease.

The research team identified three system interventions that they expect will radically reduce the environmental impact of AHPs. They say behaviour change around toilet training and greater use of reusable products can reduce product use; new and scalable recycling technologies will promote a more circular system; and developing completely compostable products can divert products from landfills and incineration to produce compost or biogas.
These products are essential for health, dignity and caregiving, but their environmental impact has largely gone under the radar. What this research shows is that this is not a problem with a single solution. It requires coordinated changes across behaviour, technology, materials and policy.

Elze Porte et al, Research priorities for addressing global absorbent hygiene product waste, Nature Sustainability (2026). DOI: 10.1038/s41893-026-01903-x

Comment by Dr. Krishna Kumari Challa 17 hours ago

Why evolution never produced mammal teeth that slice and crush equally well

Evolution is all about trade-offs. Traits that may be beneficial in one situation may backfire in another. Over millions of years, species can become specialized for one way of living rather than being equally good at everything. This explains why mammal teeth look the way they do today.

In a study published in Science, researchers investigated this exact trade-off in the carnassial (shearing) teeth of predatory mammals. They wanted to know why a single tooth rarely performs two different functions equally well. For example, it can slice but not crush, and vice versa.

To turn back the clock and understand why this is so, researchers collected lower-jaw teeth from 250 different predatory mammals, including modern bears, cats and dogs, as well as extinct prehistoric predators such as creodonts.

They mapped the exact geometry of every tooth with 3D scanners and printed 3D replicas of a representative subset to test how they work. Replicas of both modern and prehistoric teeth were put through two mechanical trials.
The research team discovered that to excel at slicing meat, a tooth must be tall and blade-like, with very little variation in shape. If it changes even slightly, slicing performance plummets.

Crushing teeth are more flexible, as nature has found many different shapes that work well. Tests showed teeth with broader, more developed crushing basins generally performed best at absorbing crushing forces.

Less than 1% of the 250 species analyzed managed to find a shape that could successfully balance both tasks. "Efficient slicers are rarely efficient crushers and vice versa," wrote the study authors in their paper.

In fact, the only two living species in the study with teeth that came closest to balancing both were the spotted hyena and the Asian palm civet.

The researchers suggest that this trade-off changed how predatory mammals evolved. While the tribosphenic tooth, an early mammal tooth that combined slicing and crushing functions, gave early mammals an advantage that drove their evolutionary success, it also imposed limits. As teeth evolved to become better at slicing or crushing, they became less effective at the other task. "The tribosphenic blueprint represents both an enabling innovation and a structural constraint."

The innovation that sparked their early success led mammals to evolve teeth specialized for different jobs instead of a single tooth that could do everything well.

Narimane Chatar et al, Performance trade-offs define a fundamental dental dichotomy in mammals, Science (2026). DOI: 10.1126/science.aee3453

Comment by Dr. Krishna Kumari Challa 17 hours ago

A spider-inspired robotic boat could track and rescue people in water

Rescue teams in coastal cities and towns often need to rescue people who are at risk of drowning. These operations often require emergency teams to locate and reach people in distress as quickly as possible, as even a short delay could have serious or even fatal consequences.

Robotic systems that can autonomously move on the surface of water, also known as unmanned surface vehicles (USVs), could potentially help search and rescue (SAR) units rapidly locate victims of maritime accidents and retrieve them from the water. Many existing USVs, however, were primarily designed to locate or approach victims on water, instead of physically rescuing them.

Researchers at Shenzhen Institute of Artificial Intelligence and Robotics for Society (AIRS) in China and Stevens Institute of Technology in the U.S. recently developed QuadBoat, a new four-legged USV that could assist agents during water rescue operations.

The new robotic boat, introduced in a paper published on arXiv preprint server, draws inspiration from fishing spiders, arachnids that can move across the surface of ponds, lakes, slow-moving streams and some other bodies of water.

Fishing spiders, the arachnids that inspired the development of QuadBoat, have long water-repellent legs that distribute their body weight over the surface of water. These legs allow them to walk and run on the surface of calm bodies of water, leveraging a force known as surface tension.
The researchers set out to develop a new USV that tries to reproduce the agile movements of fishing spiders on water, relying on conventional buoyancy to stay afloat. The robot they developed has a central body structure and four legs.

The robot's leg movements are planned, coordinated and executed by an algorithm known as an inverse kinematics controller. The researchers also developed other control algorithms that precisely steer the robot in specific directions and stabilize it while it is moving on water.

QuadBoat features a quadrupedal robot configuration, enabling it with highly adaptable and agile maneuverability through its actively adjustable posture," wrote the authors. "Employing an inverse kinematics-based controller and cascaded model predictive control (MPC)-PID controller for overall movement, QuadBoat can accurately track and retrieve objects on the water surface."

The researchers tested their robotic boat in a series of experiments inside a pool.

Lianxin Zhang et al, Design and Control of the "QuadBoat": A Quadruped Surface Vehicle for Drowning Rescue, arXiv (2026). DOI: 10.48550/arxiv.2607.13633

Comment by Dr. Krishna Kumari Challa yesterday

College professors face an emerging challenge: We know students are no longer reading entire books

Long-form book reading is declining among adults and students, with fewer adults reporting reading books and high school teachers assigning fewer complete texts. A growing share of 12th graders score below basic reading levels, indicating erosion in literacy skills. Historically central to U.S. education, reading now presents colleges with a renewed literacy crisis. The author argues that sustained engagement with difficult books is essential for independent thinking and that higher education must explicitly justify and support such reading.

original article.

Comment by Dr. Krishna Kumari Challa yesterday

From urinary tract infection to brain abscess: bacterial subpopulations can spread to distant body sites

Researchers present a clinical case in the New England Journal of Medicine that provides new insights into the evolution of bacterial pathogens and presents the concept of heterovirulence, or the simultaneous presence of subpopulations with different levels of virulence within a single infection.

The case began with a chronic urinary tract infection caused by Klebsiella pneumoniae, a common pathogen responsible for hospital-acquired infections. However, the patient subsequently developed a brain abscess. Analysis revealed that, in addition to a "classic" bacterial population, a second, significantly more virulent subpopulation existed in the patient's urine and was also present in the brain abscess.

Using whole-genome sequencing, the research team demonstrated that both populations had a common origin. Subsequent mechanistic investigations, including targeted genome modifications, functional analyses and infection models, enabled the researchers to reconstruct the evolutionary steps that led to the emergence of the increasingly virulent subpopulation.
These experiments revealed that just a few point mutations were sufficient to produce an enlarged bacterial capsule, which protected the bacteria from being taken up by immune cells and increased their virulence in infection models.

Previous work by the research group had already shown that common Klebsiella pneumoniae bacteria can become more virulent through simple mutations that lead to a larger capsule. These capsule mutants were associated with bloodstream infections, providing initial evidence of capsule subpopulations in a limited number of patient urine samples.
The case demonstrates that such processes occur within individual patients and can have clinically relevant consequences. The researchers think that the severity of an infection depends on the nature of the underlying mutations as well as the patient's condition. Aside from increasingly virulent infections, heterovirulence may also promote chronic infections.

Another important aspect highlighted by this case is that uncontrolled acute and latent infections enable the emergence of heterovirulent populations. This could be particularly relevant in the case of multidrug-resistant pathogens.

A chronic Klebsiella pneumoniae urinary tract infection contained coexisting subpopulations with distinct virulence (heterovirulence), one of which disseminated to cause a brain abscess. Whole-genome sequencing and functional analyses showed that a few point mutations enlarging the capsule increased immune evasion and virulence. Heterovirulence may drive both severe and chronic infections, especially in multidrug-resistant strains, yet remains largely undetected by current diagnostics.
The researchers see parallels to so-called heteroresistance, in which antibiotic-resistant subpopulations within an infection can complicate antibiotic treatment and are difficult to detect. However, virulent subpopulations are even more difficult to detect because bacterial virulence traits are not yet part of standard diagnostics.

The study underscores the importance of a better understanding of bacterial evolution in patients and highlights new avenues for diagnosing and treating complex infections.

Christoph M. Ernst et al, Klebsiella Brain Abscess and Evolution of Heterovirulence in the Urinary Tract, New England Journal of Medicine (2026). DOI: 10.1056/nejmc2108952

Comment by Dr. Krishna Kumari Challa yesterday

Why air travel can be so hard on the body

At any given time, hundreds of thousands of people are traveling by air. For many, these journeys will pass without consequence. But for some, a routine flight may trigger a health emergency.
Commercial flights expose passengers to reduced cabin pressure, relative hypoxia, and very low humidity, which strain cardiopulmonary function, promote dehydration, increase blood viscosity, and elevate risk of thrombosis. Gas expansion in body cavities contributes to gastrointestinal discomfort and flatulence, while postural changes, alcohol, and dehydration increase fainting risk. Cardiac and cerebrovascular events in flight are uncommon but have worse outcomes due to limited resources. Hydration, mobility, moderated alcohol intake, and timing around surgery, dental work, or diving help mitigate these risks.

original article.

Comment by Dr. Krishna Kumari Challa yesterday

Dormant pigment cells found in vitiligo patches may offer treatment target

Vitiligo is an autoimmune disease in which the body's immune system attacks and destroys melanocytes, the cells that produce the skin pigment melanin. Once the melanocytes are gone, the skin turns white, leading to the characteristic skin patches of the disease. However, the standard model of vitiligo doesn't explain some of its unusual features. Some vitiligo lesions repigment, and treatments sometimes restore pigmentation even in areas that lack melanocytes, suggesting that the melanocytes may not be fully destroyed.
Researchers found evidence that melanocytes do not completely disappear from vitiligo skin and instead enter a "dedifferentiated-like state" in which the mature cells revert to a more primitive form, losing many of their specialized functions, including pigment production.

This study uncovers a new mechanism underlying the development of vitiligo, which could change how we treat the disease.

Vitiligo lesions contain melanocytes in a dedifferentiated, pigment-silent state rather than completely lacking these cells. Basement membrane remodeling, with a shift from laminin-211 to laminin-332 and altered adhesion via integrin α3β1, drives this state and forms a self-reinforcing loop. Pharmacological inhibition of downstream signaling partially restores mature melanocyte markers and pigmentation-related gene expression, indicating reversibility and a therapeutic target.

Fei Yang et al, Aberrant laminin signaling drives melanocyte dedifferentiation and unveils a tractable therapeutic target in vitiligo, Nature Communications (2026). DOI: 10.1038/s41467-026-72064-w

Comment by Dr. Krishna Kumari Challa yesterday

A mother's devotion to newborns begins in the brain, study suggests

In mice, prolactin activates a specific hormone-sensitive pathway projecting to the brain’s reward center, increasing dopamine release and making offspring interaction intrinsically rewarding. Artificial activation of this pathway induced maternal behaviour in nulliparous mice, whereas blocking it suppressed normal maternal interest. This mechanism links prolactin-driven neural rewiring to maternal motivation and may be relevant to peripartum mood disorders.
New research has found that a hormone is responsible for making mothers' interactions with newborns feel rewarding rather than just necessary. The study, published in Science Advances, looked at how a mother's brain changes to help her devote her energy to providing for her infant's needs.
The researchers found an essential pathway in the brain that switches on when a mother is interacting with her offspring.

In mice, it runs from a hormone-sensing part of the brain into the brain's reward center—which releases dopamine—and it's switched on by prolactin, a hormone essential for milk production that also surges after birth.

When the researchers artificially activated this part of the brain, mice that had never had pups suddenly acted like devoted new mothers. When they blocked it in mothers, their normal surge of interest in pups didn't happen.
The brain's reward system gets rewired after birth to prioritize offspring. These findings help explain how that rewiring might happen, showing that prolactin acting through this specific pathway tips the balance and makes time with a new born feel rewarding rather than just necessary.
The brain is undergoing remarkable change during pregnancy that really shapes the way we think and feel. It's not surprising that sometimes these changes can be difficult. Mothers and families need support and tools to positively shape this critical period of life.
The research will help take some stigma away from parents who struggle to bond with their baby because of their biochemistry. It points to a brain pathway that isn't switching on as expected, not a personal failing.

Jenny Clarkson et al, A prolactin-receptive neural circuit drives maternal interactions with pups in mice, Science Advances (2026). DOI: 10.1126/sciadv.ady6498

Comment by Dr. Krishna Kumari Challa on Thursday

Human study links reduced inflammation to later myopia onset
Retrospective analysis of ~200 patients ≤22 years indicated that children with juvenile idiopathic arthritis receiving systemic anti-inflammatory therapy developed myopia at a later mean age (~17 years) than healthy peers (~10 years). Findings support a role for inflammation in myopia onset and suggest ocular anti-inflammatory strategies may help delay or reduce myopic progression.

Abstract: The Role of Systemic Anti-Inflammatory Agents on Refractive Development: A Retrospective Study in Children

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