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Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 11:47am

Electric fans fail to lower core body temperature of seniors during heat waves, study finds

A team of physiologists at the University of Ottawa's Human and Environmental Physiology Research Unit reports that use of an electric fan during periods of high temperatures by older people does not lower core body temperatures. In their study, published in JAMA, the group conducted experiments with elderly volunteers using fans in high-temperature conditions.

As several heat waves have struck parts of North America, high numbers of older people have died of heat stroke. This was notable due to the location of many of the deaths—the Pacific Northwest, where extremely high temperatures are rare. Because of the rarity of such high temperatures, many people in the region do not have air conditioners. Prior research has shown that older people are at higher risk of dying of heat stroke due to their lessened ability to reduce their body temperature. One notable problem is less efficient sweating.

During heat waves, officials in the affected regions suggested that older people without access to air conditioning use electric fans to stay cool. In this new effort, the research team tested the approach to see if the advice was valid.

The researchers recruited 18 people ranging in age from 65 to 72, who sat in a climate-controlled temperature chamber with an electric fan. The temperature and the fan settings were both controlled by the research team. All the volunteers were monitored during the experiments to ensure they did not become overheated.

The researchers kept the temperature inside the chamber at a steady 36°C, with a humidity level of 45%. The fans had three spin settings: off, slow and fast. All three settings were tested with the volunteers.

The researchers found that neither the slow nor the fast setting had any measurable impact on core body temperature—it was the same as if the fan was off. They also found that the slow setting did little to make the volunteers feel cooler, but the fast setting did, which, they suggest, was dangerous. Because they felt somewhat cool, the volunteers did not realize that their core body temperatures might be rising to dangerous levels.

 Fergus K. O'Connor et al, Effect of Electric Fans on Body Core Temperature in Older Adults Exposed to Extreme Indoor Heat, JAMA (2024). DOI: 10.1001/jama.2024.19457

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 11:17am

Some wildfire suppressants contain heavy metals and could contaminate the environment

In fire-prone areas, water isn't the only thing used to quell blazes. Wildland firefighters also apply chemical or synthetic suppressants. Researchers reporting in Environmental Science & Technology Letters explored whether these suppressants could be a source of elevated metal levels sometimes found in waterways after wildfires are extinguished.

Several products they investigated contained high levels of at least one metal, including chromium and cadmium, and could contribute to post-fire increases in the environment.

Wildfires are associated with the release of toxic heavy metals to the environment, but until now, it was assumed that these metals came from natural sources like soil. We now know that fire retardants may contribute to these metal releases.

Wildfire suppressant products, which are intended to inhibit fire activity before and after water evaporates, include fire retardants, water enhancers and foams. As wildfires have become more frequent and severe, larger volumes of water along with chemical and synthetic suppressants—sprayed from the ground and dropped from planes—have been required to extinguish them. Although manufacturers identify most of the active ingredients in suppressants, some components are proprietary. In addition, previous researchers have observed increased concentrations of potentially toxic metals in soil and streams after wildfires.

These results show that fire suppression activities could contribute to elevated metal levels in the environment but that more work is needed to determine potential risks to human and environmental health.

Marella H. Schammel et al, Metals in Wildfire Suppressants, Environmental Science & Technology Letters (2024). DOI: 10.1021/acs.estlett.4c00727

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:34am

Researchers show nanoplastics can reduce the effectiveness of antibiotics

In a recent study, an international research team has investigated how nanoplastic particles deposited in the body affect the effectiveness of antibiotics.

The study showed that the plastic particles not only impair the effect of the drugs, but could also promote the development of antibiotic-resistant bacteria. These results were recently published in the journal Scientific Reports.

The focus was on the broad-spectrum antibiotic tetracycline, which is used to treat many bacterial infections, such as those of the respiratory tract, skin or intestines.

When it came to plastics, the choice fell on polyethylene (PE), polypropylene (PP) and polystyrene (PS), which are ubiquitous components of packaging materials, as well as nylon 6,6 (N66), which is contained in many textiles such as clothing, carpets, sofa covers and curtains. Nanoplastics are smaller than 0.001millimeters and are considered particularly harmful to humans and the environment due to their small size.

Using complex computer models, the team was able to prove that the nanoplastic particles can bind tetracycline and thus impair the effectiveness of the antibiotic. The binding was particularly strong with nylon.

The micro- and nanoplastic load is around five times higher there than outdoors. Nylon is one of the reasons for this: it is released from textiles and enters the body via respiration, for example.

As the study results show, the binding of tetracycline to nanoplastic particles can reduce the biological activity of the antibiotic. At the same time, binding to nanoplastics could lead to the antibiotic being transported to unintended sites in the body, causing it to lose its targeted effect and possibly cause other undesirable effects.

This increase in concentration could lead to the development of antibiotic-resistant bacteria. Plastics such as nylon 6,6, but also polystyrene, which bind more strongly to tetracycline, could therefore increase the risk of resistance.

The study shows that exposure to nanoplastics is not only a direct health risk, but can also indirectly influence the treatment of diseases. If nanoplastics reduce the effectiveness of antibiotics, the dosage poses a massive problem.

Leonard Dick et al, The adsorption of drugs on nanoplastics has severe biological impact, Scientific Reports (2024). DOI: 10.1038/s41598-024-75785-4

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:26am

Comb jellies can reverse age

A new article published in Proceedings of the National Academy of Sciences reveals the unprecedented ability for reverse development in a ctenophore, also called comb jelly. The findings suggest that life cycle plasticity in animals might be more common than previously thought.

Animal life cycles typically follow a familiar pattern of decline in countless variations: they are born, grow, reproduce and die, giving way to the next generation. Only a few species are able to deviate from this general principle, the best-known example being the "immortal jellyfish" Turritopsis dohrnii, which can revert from an adult medusa back to a polyp. This elusive group of animals with flexible life cycles now includes the ctenophore Mnemiopsis leidyi.

The work challenges our understanding of early animal development and body plans, opening new avenues for the study of life cycle plasticity and rejuvenation. The fact that we have found a new species that uses this peculiar 'time-travel machine' raises fascinating questions about how spread this capacity is across the animal tree of life.

Joan J. Soto-Angel et al, Reverse development in the ctenophore Mnemiopsis leidyi, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2411499121

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:18am

It's unclear whether animals intentionally consume ethanol for ethanol's sake, and more research is needed to understand its impact on animal physiology and evolution. However, the researchers say that ethanol consumption could carry several benefits for wild animals.
First and foremost, it's a source of calories, and the odorous compounds produced during fermentation could guide animals to food sources, though the researchers say it's unlikely that animals can detect ethanol itself.

Ethanol could also have medicinal benefits: fruit flies intentionally lay their eggs in substances containing ethanol, which protects their eggs from parasites, and fruit fly larvae increase their ethanol intake when they become parasitized by wasps.

On the cognitive side, ideas have been put forward that ethanol can trigger the endorphin and dopamine system, which leads to feelings of relaxation that could have benefits in terms of sociality.

 The evolutionary ecology of ethanol, Trends in Ecology & Evolution (2024). DOI: 10.1016/j.tree.2024.09.005

Part 2

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:17am

Animal alcohol consumption more common than thought

Anecdotes abound of wildlife behaving "drunk" after eating fermented fruits, but despite this, nonhuman consumption of ethanol has been assumed to be rare and accidental. Ecologists challenge this assumption in a review published October 30 in Trends in Ecology & Evolution. They argue that since ethanol is naturally present in nearly every ecosystem, it is likely consumed on a regular basis by most fruit- and nectar-eating animals.

It is much more abundant in the natural world than we previously thought, and most animals that eat sugary fruits are going to be exposed to some level of ethanol.

Ethanol first became abundant around 100 million years ago, when flowering plants began producing sugary nectar and fruits that yeast could ferment. Now, it's present naturally in nearly every ecosystem, though concentrations are higher, and production occurs year-round in lower-latitude and humid tropical environments compared to temperate regions.

Most of the time, naturally fermented fruits only reach 1–2% alcohol by volume (ABV), but concentrations as high as 10.2% ABV have been found in over-ripe palm fruit in Panama.

Animals already harbored genes that could degrade ethanol before yeasts began producing it, but there is evidence that evolution fine-tuned this ability for mammals and birds that consume fruit and nectar. In particular, primates and tree-shrews have adapted to efficiently metabolize ethanol.

From an ecological perspective, it is not advantageous to be inebriated as you're climbing around in the trees or surrounded by predators at night—that's a recipe for not having your genes passed on.

It's the opposite of humans who want to get intoxicated but don't really want the calories—from the non-human perspective, the animals want the calories but not the inebriation.

Part 1

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:12am

The constraint imposed on the tissue geometry by the channel walls affects the patterns of mechanical stress experienced by the Hydra tissue, from both the hydrostatic pressure gradient across the tube and the frequent muscle contractions that take place.

The group found there was a strong preference of the body axes and the actomyosin fiber to come into alignment with the "easy-axis" of the channel, with one head and one foot along the channel axis. But different body plans developed if the initial tissue was perpendicular to the channel axis.

They wrote, "samples that are initially oriented with their primary fiber alignment perpendicular to the channel direction often regenerate into multiaxial morphologies."

But if the animals that were confined in length, perpendicular to the channel axis, they consisted mostly of animals with, amazingly, two heads, and often more than one foot. These multiple morphological features are not arranged along a single axis, but rather at junctions between axes with particular topological defects in the fiber organization.

Yonit Maroudas-Sacks et al, Confinement Modulates Axial Patterning in Regenerating Hydra, PRX Life (2024). DOI: 10.1103/PRXLife.2.043007

Part 3

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Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:11am

In the group's earlier work, they focused on the role of multi-cellular arrays of actomyosin fibers in guiding and stabilizing the body axis of the Hydra as they regenerated. (Actomyosin is a complex formed by two interacting proteins, actin and myosin. It plays crucial roles in muscle contraction and cell movement, with the myosin motor protein pulling the actin filaments into place.)

Hydra have parallel actomyosin fibers that contract, and previous work by the same group found that the body axis of Hydra regenerated when tissue segments were aligned with the inherited body axis of the parent.

They decided to investigate how the orientation field of the actomyosin fibers, which contained locally disordered regions called topological defects, is relevant to the body plan of Hydra morphogenesis, which was still unknown.

They developed a methodology to confine regenerating Hydra in an anisotropic manner—on an axis other than the Hydra's parallel fibers. This required a method of confinement that did not damage the organism's tissue or regenerating capacity over the course of several days. They also needed high resolution live imaging over the entire time of regeneration.

The confinement was in a glass capillary tube, equipped with small cylindrical channels on its inner surface, 120 to 300 microns wide, made of a stiff gel between the spherical tissue samples and the glass wall.

When the Hydra tissue was introduced into the resulting channel, while a softer gel was pushed into the channel cavities on the edges to create a width available to the Hydra, care was taken not to tear the tissue during the soft gel insertion.

This reduced the movement of the tissue along the cylinder axis, with about 20 to 50 cells along the circumference of the cavity (a typical cell size is 20 microns), while allowing the spherical tissue to unfold and regenerate into an elongated, ellipsoidal shape.

After some time, the regenerating tissue fills the channel available to it, then forms a mouth and tentacles as the body column becomes narrower than the channel, and the animal separates from the channel walls.

In this way, an angle develops between the constrained body axis and the inherited body axis. The relative angle between the inherited body axis and the channel axis depends on the orientation in which the Hydra tissue spheroid enters the channel, with its inherited axis parallel or perpendicular to the channel's axis.
Part 2

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:11am

Constraining the body of a hydra can cause it to grow two heads

Hydra are small, invertebrate, predatory animals that live in water. They're tubular, radially symmetric and up to 10 mm long, with a head (mostly a mouth), a single, adhesive foot, and tentacles.

In a study published in the journal PRX Life, researchers investigated how technical forces and feedbacks on a Hydra might affect its body plan.

They choose Hydra because they are notable for being able to regenerate, as most of their body cells are stem cells, which can continually divide and then differentiate into any of the body's cell types. In fact, Hydra are so good at it that do not appear to age and may be immortal, constantly regenerating whatever cells they need, even from an initial small piece of tissue.

All animals share a common body plan because all come from a common ancestor, including bilateral symmetry, segmented bodies and a digestive system. Over billions of years, evolution has modified their shapes to create the enormous variety of body morphologies observed in the animal kingdom. But this biological pattern formation is still not well understood.

Morphogenesis is the biological process that causes a cell, tissue, or organism to develop its shape. It involves the differentiation of cells, tissues, and organs, leading to the creation of order in the developing organism.

Morphogenesis is a fundamental aspect of developmental biology, alongside tissue growth control and cellular differentiation. But what if an organism is constrained in some way due to external forces?

In this study, a team of researchers confined Hydra into a narrow cylindrical channel. The channel constrained the morphology of the animal—the form and structure of an organism, and particular features of its structure.

Part 1

Comment by Dr. Krishna Kumari Challa on October 30, 2024 at 12:35pm

What is transcranial ultrasound stimulation (TUS)?

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