Comment

Comment by Dr. Krishna Kumari Challa on February 25, 2023 at 10:49am

Human height remained unchanged for 2,000 years in Milan, finds study

A study covering 2,000 years of male and female adult statures in Milan, Italy, has been published in the journal Scientific Reports, illustrating a stable environmental influence on height.

Human height depends on an interplay between genetics and environmental factors like fetal health, childhood nutrition, disease exposures, as well as environmental epigenetic factors that can reach back generations. While genetics alone may determine how tall a person could become, the environment they are born into plays a significant role in how much of that genetic growth potential is realized. Typically when we look around the world, we see that as health and nutrition have become more reliable since the industrial revolution, humans have reached increasingly greater heights.

In past studies, population stature has been linked to environmental factors. Human height dramatically reduced during the switch from hunter-gatherers to more agricultural societies. Human height has been slowly increasing since then, occasionally being shown to wax and wane with times of sustained prosperity, wars, famines, climate change, and exposure to plague.

In the study, researchers analysed 549 skeletal remains from 13 different sites, all within Milan. The remains all came from necropolises dedicated to the less wealthy classes of Milanese society. They were assigned to one of five historical periods: Roman Era (first–fifth centuries AD), Early Middle Ages (sixth–tenth centuries AD), Late Middle Ages (eleventh–fifteenth centuries AD), Modern Era (sixteenth–eighteenth centuries AD) and Contemporary Era (nineteenth–twentieth centuries AD).

About 100 individuals were assessed for each era, split between male and female. Stature was estimated, mostly using femur bones, according to a well-established forensic regression formula. Individual female heights ranged from 143.5 to 177.6 cm, with a mean of 157.8 cm (about 5'2''). Males ranged from 152.0 to 195.4 cm, with a mean of 168.5 cm (5'6''). There was no significant change in average heights when comparing the historical periods.

By focusing their study on a single geographic location with similar urban and socioeconomic characteristics, researchers were able to remove biases that might arise in studies of multiple populations with distinct environmental influences. With such a homogenous environment, external forces on population height, like wars, plagues, or climate, should have been obvious. Surprisingly, there were no significant fluctuations seen in the statures. Suggesting to the study authors that city life in Milan has provided a stable environment for thousands of years, even for its lowest-income inhabitants.

 Lucie Biehler-Gomez et al, The diachronic trend of female and male stature in Milan over 2000 years, Scientific Reports (2023). DOI: 10.1038/s41598-023-28406-5

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Comment by Dr. Krishna Kumari Challa on February 23, 2023 at 2:45pm

Spinal cord stimulation shown to instantly improve arm mobility after stroke

Neurotechnology that stimulates the spinal cord instantly improves arm and hand mobility, enabling people affected by moderate to severe stroke to conduct their normal daily activities more easily, report researchers.

A pair of thin metal electrodes resembling strands of spaghetti implanted along the neck engage intact neural circuits, allowing stroke patients to fully open and close their fist, lift their arm above their head or use a fork and knife to cut a piece of steak for the first time in years.

They discovered that electrical stimulation of specific spinal cord regions enables patients to move their arm in ways that they are not able to do without the stimulation. Perhaps even more interesting, they found that after a few weeks of use, some of these improvements endure when the stimulation is switched off, indicating exciting avenues for the future of stroke therapies.

Spinal cord stimulation technology uses a set of electrodes placed on the surface of the spinal cord to deliver pulses of electricity that activate nerve cells inside the spinal cord. This technology is already being used to treat high-grade, persistent pain. Additionally, multiple research groups around the world have shown that spinal cord stimulation can be used to restore movement to the legs after spinal cord injury.

But the unique dexterity of the human hand, combined with the wide range of motion of the arm at the shoulder and the complexity of the neural signals controlling the arm and hand, add a significantly higher set of challenges.

Following years of extensive preclinical studies involving computer modeling and animal testing in macaque monkeys with partial arm paralysis, researchers were cleared to test this optimized therapy in humans.

The sensory nerves from the arm and hand send signals to motor neurons in the spinal cord that control the muscles of the limb.

By stimulating these sensory nerves, one can amplify the activity of muscles that have been weakened by stroke. Importantly, the patient retains full control of their movements: The stimulation is assistive and strengthens muscle activation only when patients are trying to move.

In a series of tests adapted to individual patients, stimulation enabled participants to perform tasks of different complexity, from moving a hollow metal cylinder to grasping common household objects, such as a can of soup, and opening a lock. Clinical assessments showed that stimulation targeting cervical nerve roots immediately improves strength, range of movement and function of the arm and hand.

Unexpectedly, the effects of stimulation seem to be longer-lasting than scientists originally thought and persisted even after the device was removed, suggesting it could be used both as an assistive and a restorative method for upper limb recovery. Indeed, the immediate effects of the stimulation enable administration of intense physical training that, in turn, could lead to even stronger long-term improvements in the absence of the stimulation.

Moving forward, researchers continue to enroll additional trial participants to understand which stroke patients can benefit most from this therapy and how to optimize stimulation protocols for different severity levels.

Marco Capogrosso, Epidural stimulation of the cervical spinal cord for post-stroke upper-limb paresis, Nature Medicine (2023). DOI: 10.1038/s41591-022-02202-6. www.nature.com/articles/s41591-022-02202-6

Comment by Dr. Krishna Kumari Challa on February 23, 2023 at 12:39pm

Anti-dust tech paves way for self-cleaning surfaces

Dust is a common fact of life, and it's more than just a daily nuisance—it can get into machinery and equipment, causing loss of efficiency or breakdowns.

Researchers  developed a new method to keep dust from sticking to surfaces. The result is the ability to make many types of materials dust resistant, from spacecraft to solar panels to household windows. They demonstrated  a surface that can clean itself. Particulates aren't able to stick to the surface, so they come off using just the force of gravity.

In tests, the researchers piled lunar dust on top of their engineered surfaces and then turned each surface on its side. The result: Only about 2% of the surface remained dusty, compared with more than 35% of a similarly smooth surface.

The researchers said the discovery boils down to things the human eye can't detect. In the experiments, the team altered the geometry of flat surfaces to create a tightly packed nanoscale network of pyramid-shaped structures. These sharp, angular structures make it difficult for the dust particles to stick to the material, instead sticking to one another and rolling off the material via gravity.

These structures provide a passive solution, meaning they don't require any extra energy or materials to remove dust. Compare that with more active solutions such as a car windshield that requires the use of windshield wipers and wiper fluid to clean off dust.

Samuel S. Lee et al, Engineering large-area anti-dust surfaces by harnessing interparticle forces, ACS Applied Materials & Interfaces (2023). DOI: 10.1021/acsami.2c19211. pubs.acs.org/doi/10.1021/acsami.2c19211

Comment by Dr. Krishna Kumari Challa on February 23, 2023 at 12:30pm

Certain fitness and wellness trackers could pose serious risks for people with cardiac implantable electronic devices (CIEDs) such as pacemakers, implantable cardioverter defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. Credit: Heart Rhythm

But after conducting comprehensive testing of bioimpedance on three cardiac CRT devices from manufacturers Medtronic, Boston Scientific, and Abbott, Sanchez Terrones' team learned the slight electrical currents from these wearable gadgets can interfere and sometimes confuse cardiac implantable devices into operating incorrectly.

In the case of a pacemaker, which sends small electrical impulses to the heart when it is beating too slowly, the bioimpedance's tiny electrical current could trick the heart into thinking it is beating fast enough, preventing the pacemaker from doing its job when it is supposed to.

Safety evaluation of smart scales, smart watches, and smart rings with bioimpedance technology shows evidence of potential interference in cardiac implantable electronic devices, Heart Rhythm (2023). DOI: 10.1016/j.hrthm.2022.11.026

Part 2

Comment by Dr. Krishna Kumari Challa on February 23, 2023 at 12:28pm

Study shows certain wearable gadgets could interfere with implantable cardiac electronic devices

In this high-tech era, wearable devices such as smartwatches have proven to be invaluable companions for the health conscious. But a new study shows that for a small group of people, some of these electronic fitness gadgets could possibly be risky to their health—even potentially deadly.

This new study  shows that wearable devices such as the Samsung Galaxy watch 4, Fitbit smart scales, or Moodmetric smart rings, among others, have sensing technology that could interfere with cardiac implantable electronic devices (CIEDs) such as pacemakers, implantable cardioverter defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices.

This study raises a red flag. Researchers  have done this work in simulations and benchtop testing following Food and Drug Administration accepted guidelines, and these gadgets interfere with the correct functioning of the CIEDs they tested. These results call for future clinical studies evaluating the translation of their findings to patients wearing CIEDs and using these wearable devices.

Part 1

Comment by Dr. Krishna Kumari Challa on February 23, 2023 at 12:23pm

Study finds 'forever chemicals' disrupt key biological processes

A team of researchers  found that exposure to a mixture of synthetic chemicals found widely in the environment alters several critical biological processes, including the metabolism of fats and amino acids, in both children and young adults. The disruption of these biological processes is connected to an increased risk of a very broad range of diseases, including developmental disorders, cardiovascular disease, metabolic disease and many types of cancer.

Known as per- and polyfluoroalkyl substances, or PFAS, these man-made chemicals are used in a wide range of consumer and industrial products. PFAS are sometimes called "forever chemicals" because they break down very slowly and accumulate in the environment and human tissue.

Although individual PFAS are known to increase the risk of several types of disease, this study, published February 22 in Environmental Health Perspectives, is the first to evaluate which biological processes are altered by exposure to a combination of multiple PFAS, which is important because most people carry a mixture of the chemicals in their blood.

In this new study, it was found that exposure to a combination of PFAS not only disrupted lipid and amino acid metabolism but also altered thyroid hormone function.

Another important finding was the fact that exposure to a mixture of PFAS, rather than a single chemical of this type, drove the disruption of these biological processes. This finding was consistent across the two cohorts, even though they had different levels of PFAS exposure.

Metabolic signatures of youth exposure to mixtures of per- and polyfluoroalkyl 2 substances: A multi-cohort study, Environmental Health Perspectives (2023). DOI: 10.1289/EHP11372

Comment by Dr. Krishna Kumari Challa on February 23, 2023 at 11:07am

Discovery of massive early galaxies defies prior understanding of the universe

Six massive galaxies discovered in the early universe are upending what scientists previously understood about the origins of galaxies in the universe.

These objects are way more massive than anyone expected. Researchers expected only to find tiny, young, baby galaxies at this point in time, but they've discovered galaxies as mature as our own in what was previously understood to be the dawn of the universe.

Using the first dataset released from NASA's James Webb Space Telescope, the international team of scientists discovered objects as mature as the Milky Way when the universe was only 3% of its current age, about 500-700 million years after the Big Bang. The telescope is equipped with infrared-sensing instruments capable of detecting light that was emitted by the most ancient stars and galaxies. Essentially, the telescope allows scientists to see back in time roughly 13.5 billion years, near the beginning of the universe as we know it.

But scientists think this is their first glimpse back this far, so it's important that they keep an open mind about what they are seeing. While the data indicates they are likely galaxies, they think there is a real possibility that a few of these objects turn out to be obscured supermassive black holes. Regardless, the amount of mass they discovered means that the known mass in stars at this period of our universe is up to 100 times greater than they had previously thought. Even if they cut the sample in half, this is still an astounding change.

In a paper published recently (Feb. 22) in Nature, the researchers show evidence that the six galaxies are far more massive than anyone expected and call into question what scientists previously understood about galaxy formation at the very beginning of the universe.

The revelation that massive galaxy formation began extremely early in the history of the universe upends what many of us had thought was settled science. Scientists have been informally calling these objects 'universe breakers'—and they have been living up to their name so far.

 Accounting for such a high amount of mass would require either altering the models for cosmology or revising the scientific understanding of galaxy formation in the early universe—that galaxies started as small clouds of stars and dust that gradually grew larger over time. Either scenario requires a fundamental shift in our understanding of how the universe came to be.

One way to confirm the team's finding and alleviate any remaining concerns would be to take a spectrum image of the massive galaxies. That would provide the team data on the true distances, and also the gasses and other elements that made up the galaxies. The team could then use the data to model a clearer of picture of what the galaxies looked like, and how massive they truly were. A spectrum will immediately tell us whether or not these things are real. 

 Ivo Labbe, A population of red candidate massive galaxies ~600 Myr after the Big Bang, Nature (2023). DOI: 10.1038/s41586-023-05786-2. www.nature.com/articles/s41586-023-05786-2

Comment by Dr. Krishna Kumari Challa on February 22, 2023 at 11:29am

Although the effects of senescence may seem paradoxical at first sight, recent studies show that it is all a question of temporality... and context. "In the short term, the secretome is involved in recruiting immune cells to eliminate tumor cells. But in the long term, the accumulation of senescent cells can promote the destruction of the extracellular matrix—which allows the organization of cells into tissue—and the proliferation of malignant cells." The researchers wondered whether there was senescence in glioblastoma and, if so, what role it might play in the cancer progression. To do this, they investigated both an animal model of glioblastoma and tumor tissue removed from patients during surgery. The team first examined 28 patient tumors. They found, in varying proportions (0.4% to 7% of the original mass of glioblastoma), senescent cells of different cell types—tumoral, immune, or glial—located mainly in areas of malignant cell proliferation, as well as in necrosis zones. In mice, suppressing a part of the senescent tumor cells made it possible to modify the immune activity within the tumor and extend the animal's lifespan. The researchers then defined a characteristic signature of senescence based on the expression of 31 genes in mice and ensured that it was identical in humans. Researchers observed that the strong expression of this signature was associated with a poor prognosis. This shows the pro-tumor action of senescence in glioblastoma. Modulating cellular senescence could therefore constitute a new therapeutic avenue to be combined with conventional treatments—to increase their effectiveness.

Rana Salam et al, Cellular senescence in malignant cells promotes tumor progression in mouse and patient Glioblastoma, Nature Communications (2023). DOI: 10.1038/s41467-023-36124-9

Part 2

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Comment by Dr. Krishna Kumari Challa on February 22, 2023 at 11:27am

Cellular senescence plays a significant role in cerebral tumours

Glioblastomas are the most common malignant tumors of the adult brain. They resist conventional treatment, including surgery, followed by radiation therapy and chemotherapy. Despite this armamentarium, glioblastomas inexorably recur.

In a new study published in Nature Communications, researchers have shown that the elimination of senescent cells, i.e., cells that have stopped dividing, can modify the tumor ecosystem and slow its progression. These results open up new avenues for treatment.

Glioblastoma, the most common adult brain cancer, affects 2 to 5 in 100,000 individuals. While the incidence of the disease is highest in those between 55 and 85 years old, it is increasing in all age groups. This effect can't be attributed to improved diagnostic techniques alone, suggesting the influence of environmental factors hitherto unidentified.

People with the disease have a median survival of 15 months after diagnosis, as the tumor infiltrates the brain very quickly. There is an urgent need to better understand the biology of the tumor, including the diversity of cell types of which it is composed, and their role. The challenge is to find new therapeutic targets and significantly increase the lifespan of patients.

Finding the weak spot of glioblastoma is no easy task. One recent approach consists in targeting a key biological process: cellular senescence. Initially identified during the normal aging of cells, it corresponds to the loss of their ability to divide. Interruption of the cell cycle has an advantage: it prevents the uncontrolled division of malignant cells. In that case, senescence contributes to the body's anti-tumor response.

Long considered a simple marker of aging, we now know that senescence occurs throughout life, especially in response to genotoxic stress—that is, an event that disrupts or damages DNA, such as chemotherapy

When cells enter senescence, they secrete various molecules. This is called the senescence-associated secretory phenotype—or secretome. The secretome can influence the cellular environment in a beneficial or detrimental way. For example, it can activate the immune system or, conversely, induce the formation of blood vessels that contribute to the irrigation of the cancerous tissue. It all depends on the molecules secreted.

Part 1

Comment by Dr. Krishna Kumari Challa on February 22, 2023 at 11:09am

Physicists create new model of ringing black holes

When two black holes collide into each other to form a new bigger black hole, they violently roil spacetime around them, sending ripples, called gravitational waves, outward in all directions. Previous studies of black hole collisions modeled the behavior of the gravitational waves using what is known as linear math, which means that the gravitational waves rippling outward did not influence, or interact, with each other. Now, a new analysis has modeled the same collisions in more detail and revealed so-called nonlinear effects.

Nonlinear effects are what happens when waves on the beach crest and crash. The waves interact and influence each other rather than ride along by themselves. With something as violent as a black hole merger, researchers expected these effects but had not seen them in their models until now. New methods for extracting the waveforms from their simulations have made it possible to see the nonlinearities.

In the future, the new model can be used to learn more about the actual black hole collisions that have been routinely observed by LIGO (Laser Interferometer Gravitational-wave Observatory) ever since it made history in 2015 with the first direct detection of gravitational waves from space. LIGO will turn back on later this year after getting a set of upgrades that will make the detectors even more sensitive to gravitational waves. Supercomputers are needed to carry out an accurate calculation of the entire signal: the inspiral of the two orbiting black holes, their merger, and the settling down to a single quiescent remnant black hole.

Keefe Mitman et al, Nonlinearities in black hole ringdowns, Physical Review Letters (2023). Accepted for publication: journals.aps.org/prl/accepted/ … 5c5aaa672c0e199adcff. On Arxiv: DOI: 10.48550/arxiv.2208.07380

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