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Comment by Dr. Krishna Kumari Challa on Wednesday

Fat breakdown in skin cells restarts hair growth in mice

Researchers  report that adipocyte lipolysis activates epithelial hair follicle stem cells and drives hair regeneration via monounsaturated fatty acid signaling.

Healthy hair follicles are still present in balding men, but they are often miniaturized, producing thinner, weaker hairs that eventually stop producing. For a while, even though the follicles stop growing visible hair, previous studies show they still contain stem cells and could, theoretically, be reactivated.

Skin is a lipid-rich organ where fatty tissue cushions, insulates, and secretes endocrine factors. Previous studies have linked inflammation after minor injury to hair regrowth and have described crosstalk between dermal white adipose tissue and hair follicle stem cells with both stem cell activation and dormancy. Specific roles for adipocytes in regeneration remained unclear.

In the study, "Adipocyte lipolysis activates epithelial stem cells for hair regeneration through fatty acid metabolic signaling," published in Cell Metabolism, researchers employed mouse models of skin injury to determine whether inflammation-triggered adipocyte lipolysis promotes hair regrowth and to define the downstream metabolic pathway in epithelial hair follicle stem cells.

Mouse experiments were conducted using topical sodium dodecyl sulfate (SDS) irritation and controlled dermal laser injury, with female mice used predominantly. Mice were shaved on postnatal day 49 to synchronize with the start of the second telogen phase, when hair follicles are naturally resting and hair doesn't normally regrow for about six weeks.

Investigators applied 7.5% SDS to induce contact dermatitis, tracked timing of epidermal and follicular responses by histology, EdU labeling, lipid testing and immunostaining, and profiled transcripts with bulk and spatial transcriptomics.
Skin irritation produced rapid skin redness and scaling at the surface, outer skin thickened and immune cells flooded in. Several days later, growth of new hair was observed.
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Comment by Dr. Krishna Kumari Challa on Wednesday

Over 3.5 years, the team studied 8,073 older adults aged 73 to 91. They tracked how quickly participants lost teeth over time, measuring this as the average number of teeth lost per year. Based on the tooth loss pattern, the participants were divided into four groups: stable (no teeth lost per year), slow loss (more than zero but less than two teeth lost per year), moderate loss (two to under four teeth lost per year), and rapid loss (4 or more teeth lost per year).

The data were then entered into a Cox regression analysis—a statistical method that accounts for the relative risk of an event—to determine whether faster tooth loss was associated with a higher mortality risk. They found that those with rapid tooth loss had a 33% higher risk of death compared to those who lost none. Also, with each tooth lost per year, the risk increases by 4%.

The researchers note that further investigation into the mechanisms underlying this relationship is needed to develop effective interventions. Until then, raising awareness of the hidden health risks of rapid tooth loss among both health care professionals and the public could go a long way toward encouraging habit modification.

Linjia Duan et al, Tooth loss progression and mortality among older adults: results from the Chinese longitudinal healthy longevity survey (CLHLS), BMC Geriatrics (2025). DOI: 10.1186/s12877-025-06419-1

Part 2

Comment by Dr. Krishna Kumari Challa on Wednesday

Rapid tooth loss linked to higher risk of death in older people

In older adults, tooth loss may be linked to serious health risks. A team of  researchers analyzed data from 8,073 older participants and found that people who lost their teeth more quickly had a higher risk of dying, regardless of how many teeth they started with.

The researchers emphasize the need to closely monitor the progression of tooth loss among older adults, as it is an important indicator of broader physiological decline.

Modifiable habits like regular brushing, avoiding smoking, and routine dental checkups play a key role in how quickly teeth are lost. Studies show that consistent oral care can lower mortality rates among older adults with missing teeth. Making oral health a stronger focus of public health efforts could be an easy way to improve overall well-being, suggests the study published in BMC Geriatrics.

Old age or not, oral health is a major problem in humans across the globe. In 2022, the World Health Organization released a "Global Oral Health Status Report," which showed that almost half of the world's population (~3.5 billion people) has some form of dental disease. It highlighted tooth loss as one of the most common problems.

While losing teeth with age is often inevitable, its impact can be far-reaching. It not only affects quality of life by making it harder to chew and enjoy food, but has also been linked to higher death rates—not just overall mortality, but from specific causes like heart disease, lung cancer, and pneumonia.

Part 1

Comment by Dr. Krishna Kumari Challa on Tuesday

Exploring mechanisms behind attachment issues

Stoicism says attachment is not good. But  overcoming biochemistry is extremely difficult. Especially when you are young. 

And then not giving enough care also makes people detached. 

Children can sometimes develop health, behavioral, and attachment issues that persist when their needs are not met by their caregiver. Now from eNeuro, researchers explored whether mouse pups also experience these issues from early life adversity.

Their discoveries provide an opportunity for researchers to explore the mechanisms of health and behavioral deficits from early life adversity.

When the researchers limited bedding for making nests, this impaired maternal care and increased stress hormone signaling in pups after just one week. Offspring also experienced long-term stunted growth trajectories.

Behaviorally, while some attachment behaviors remained unchanged, many were affected: Pups vocalized less when they were separated from their mothers after one week, did not approach their mothers after about two weeks, and had anxiety-like behavior by week three.

Giving credit where credit is due, work in rats relates an increased stress response from impaired maternal care to attachment deficits. But this work was only done in one age group. Researchers used thorough, 24/7 videotape footage of moms and their pups to show how impaired maternal care leads to attachment deficits at different timepoints.

This isn't a linear relationship. It seems that there is a threshold for how bad maternal care must be to disrupt the offspring's behavior. This supports an existing hypothesis that you don't have to be a perfect parent, you just need to provide adequate care.

Erratic Maternal Care Induces Avoidant-Like Attachment Deficits in a Mouse Model of Early Life Adversity, eNeuro (2025). DOI: 10.1523/ENEURO.0249-25.202

Comment by Dr. Krishna Kumari Challa on Tuesday

Most often the behavior was directed at the chimpanzee's own open wound. However, in one rare instance, an adolescent female applied an insect to her brother's wound. A study on the same community has shown that chimpanzees also dab the wounds of unrelated members with leaves, prompting the question of whether insect application of these chimpanzees, too, might extend beyond family members. Acts of care, whether directed towards family or others, can reveal the early foundations of empathy and cooperation.

 Kayla Kolff et al, Insect applications to open wounds by chimpanzees in the wild: first insights from East African chimpanzees, Scientific Reports (2025). DOI: 10.1038/s41598-025-16582-5

Part2

Comment by Dr. Krishna Kumari Challa on Tuesday

Chimpanzees in Uganda use flying insects to tend their wounds, study reveals

Animals respond to injury in many ways. So far, evidence for animals tending wounds with biologically active materials is rare. Yet, a recent study of an orangutan treating a wound with a medicinal plant provides a promising lead.

Chimpanzees, for example, are known to lick their wounds and sometimes press leaves onto them, but these behaviors are still only partly understood. We still do not know how often these actions occur, whether they are deliberate, or how inventive chimpanzees can be when responding to wounds.

Recent field observations in Uganda, east Africa, are now revealing intriguing insights into how these animals cope with wounds.

In  research published in Scientific Reports, based in Kibale National Park, Uganda, chimpanzees have been seen applying insects to their own open wounds on five occasions, and in one case to another individual.

Behaviors like insect application show that chimpanzees are not passive when wounded. They experiment with their environment, sometimes alone and occasionally with others. While we should not jump too quickly to call this "medicine," it does show that they are capable of responding to wounds in inventive and sometimes cooperative ways.

Each new insight reveals more about chimpanzees, offering glimpses into the shared evolutionary roots of our own responses to injury and caregiving instincts.

In all observed cases, the sequence of actions seemed deliberate. A chimpanzee caught an unidentified flying insect, immobilized it between lips or fingers, and pressed it directly onto an open wound. The same insect was sometimes reapplied several times, occasionally after being held briefly in the mouth, before being discarded. Other chimpanzees occasionally watched the process closely, seemingly with curiosity. Part1

Comment by Dr. Krishna Kumari Challa on Tuesday

The researchers broke down human movement by mode of transportation. They found that about 65% of human biomass movement is by car or motorbike, 10% by airplane, 5% by train and 20% by foot or on a bicycle. Remarkably, the biomass movement of humans walking is six times greater than that of all wild land mammals, birds and arthropods combined.

On average, each person travels about 30 kilometers a day by various means—slightly more than wild birds. By comparison, wild land mammals (excluding bats) travel only about 4 kilometers a day. In the air, human biomass movement by airplane is ten times greater than that of all flying wildlife.

We often marvel at the power of nature compared to how small we are. But in practice, even the great migrations we see in Africa in nature documentaries—some of the largest land migrations on Earth—barely compare to the human biomass movement associated with people gathering from around the world for a single World Cup tournament.
Animals spend a large portion of their energy on movement, and measuring their biomass movement enabled the scientists to compare the energetic cost of transport across species. Scientists found, for example, that a single airline burns as much energy as all wild birds combined. It may be hard to grasp just how much humankind affects nature, but the biomass movement metric does provide a quantitative measure that reveals the true balance of power on Earth.
This power balance is dramatically changing. Humanity continues to develop and expand while nature is in decline. Most biomass movement occurs in the oceans, but even those vast habitats are severely affected by human activity now.
Since the Industrial Revolution, human biomass movement has soared by 4,000%, while that of marine animals has dropped by about 60%.
Today we know that animal movement is critical for ecosystems to function properly and that ecosystems must remain connected to one another to survive. The global decline in animal movement is a warning sign to us all, say the researchers.

Yuval Rosenberg et al, Human biomass movement exceeds the biomass movement of all land animals combined, Nature Ecology & Evolution (2025). DOI: 10.1038/s41559-025-02863-9

Lior Greenspoon et al, The global biomass of mammals since 1850, Nature Communications (2025). DOI: 10.1038/s41467-025-63888-z

Part 2

Comment by Dr. Krishna Kumari Challa on Tuesday

Humanity rises as wildlife recedes: Two studies show the extent of human domination over nature

Wolves roaming the Mongolian steppes cover more than 7,000 kilometers a year. The Arctic tern flies from pole to pole in its annual migration. Compared to these long-distance travelers of land, sea and sky, humans might seem like the ultimate couch potatoes. But a new study shows otherwise.

In a paper published recently in Nature Ecology & Evolution,  researchers report that the total movement of humans is 40 times greater than that of all wild land mammals, birds and arthropods combined. Since the Industrial Revolution some 170 years ago, human movement has skyrocketed, while animal movement in nature has dwindled to levels that could endanger ecosystems.

Life, by its very nature, is always in motion, shaping both the natural world and human society. Yet until now, no comparison has been made among different species as to the magnitude of their overall movement. Birds, for example, cross vast distances but their overall body mass is tiny. By contrast, deep-sea fish may travel only short distances, but their combined biomass is enormous—about a thousand times greater than that of all birds.

Researchers  have now quantified and compared the movement of different species, shedding light on the power dynamics between humans and the rest of the animal kingdom.

The index they created, called the biomass movement metric, is calculated by multiplying the total biomass of a species—that is, the combined mass of all its members—by the total distance that species travels in a year. Calculating this metric globally made it possible, for the first time, to quantify global movement across animal species—and then compare it to that of humankind.

Part 1

Comment by Dr. Krishna Kumari Challa on Tuesday

How a coral stiffens its skeleton on demand

Touch the branches of Leptogorgia chilensis, a soft coral found along the Pacific coast from California to Chile, and its flexible arms stiffen. Researchers have discovered the mechanism underlying this astonishing ability, one that could advance fields as varied as medicine, robotics and manufacturing.

In a paper in Proceedings of the National Academy of Sciences,

they describe how the coral's skeleton—made of millions of mineral particles suspended in a gelatinous matrix—compacts itself to ward off danger.

When stimulated, the coral's tissues expel water, shrinking the gel and squeezing the particles closer together until they jam in place.

Physicists have long studied this phenomenon, known as "granular jamming," by manipulating grainy substances like sand and coffee grounds, but this marks the first time granular jamming based on hard particles has been observed in a living organism.

They're basically made of chalk- calcium carbonate, the same cheap and plentiful white powder that forms eggshells, sticks of chalk, marble, limestone and pearls. What gives their skeletons interesting properties is how the calcium carbonate is structured and organized.

While marine biologists recognized long ago that soft corals like L. chilensis have skeletons containing granular particles, the grains' shapes had primarily been used to classify different species.

Li, Ling, Mineralized sclerites in the gorgonian coral Leptogorgia chilensis as a natural jamming system, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2504541122. doi.org/10.1073/pnas.2504541122

Comment by Dr. Krishna Kumari Challa on Tuesday

Study links cockroach infestations to higher household allergens and endotoxins

Researchers have shown a link between the size of cockroach home infestations and the levels of both allergens and endotoxins in those homes, with lowering roach infestation numbers through pest control triggering significant declines in the levels of allergens and endotoxins. The study's findings suggest that eliminating cockroach infestations could help improve indoor environmental health by greatly reducing allergens and endotoxins.

Endotoxins are bacterial cellular components that get released when bacteria die. As omnivores that will eat just about anything, cockroaches have a rich and diverse gut microbiome. Previous research has shown that cockroaches shed a lot of endotoxins through their fecal matter, although house pets – and humans – can also shed endotoxins. The researchers in this study found that a large amount of the endotoxins found in household dust was associated with cockroach feces.

Endotoxins are important to human health, as inhalation of these components has been shown to provoke allergic responses. 

The researchers found significant amounts of endotoxins in infested homes, with female cockroaches excreting about twice the amount that males excreted. Female cockroaches eat more than males, so more endotoxins are shed from their fecal matter.  More endotoxins were found in kitchens than in bedrooms, as more cockroaches live in kitchens where they find more food.

When you eliminate cockroaches, you eliminate their allergens. Small decreases in cockroaches don't lower allergen levels because the remaining live cockroaches deposit more allergens. Endotoxins significantly decreased in homes where cockroaches were eliminated. This research shows that the cockroach is the most important depositor of endotoxin in infested homes.

Researchers  also saw that allergens and endotoxins can be airborne. 

There exists the implication that asthma can be worse due to interactions between allergens and endotoxins.

Cockroaches?! Eeek!

I don't have a single cockroach in my home. Because I don't like them, I see to it they don't come inside my home. 

 Madhavi L. Kakumanu et al, Indoor Allergens and Endotoxins in Relation to Cockroach Infestations in Low-Income Urban Homes, Journal of Allergy and Clinical Immunology: Global (2025). DOI: 10.1016/j.jacig.2025.100571

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