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Comment by Dr. Krishna Kumari Challa on November 4, 2023 at 9:27am

Wearable devices may prevent astronauts getting 'lost' in space

Taking space  flight is dangerous. In leaving the Earth's surface, we lose many of the cues we need to orient ourselves, and that spatial disorientation can be deadly. Astronauts normally need intensive training to protect against it. But scientists have now found that wearable devices which vibrate to give orientation cues may boost the efficacy of this training significantly, making spaceflight slightly safer.

Long-duration spaceflight will cause many physiological and psychological stressors, which will make astronauts very susceptible to spatial disorientation. When disoriented, an astronaut will no longer be able to rely on their own internal sensors, which they have depended on for their whole lives.
Part 1

Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 9:35am

Neurons in the brain stop working very quickly if you deprive them of oxygen or glucose. If you add oxygen again, they’ll simply resume their work and do so just as quickly.

To better understand what happens inside the brain during syncope, the researchers used electrodes to record the activity of thousands of neurons from various brain regions in mice as the animals fainted. Activity decreased in all areas of the brain, except one specific region of the hypothalamus known as the periventricular zone (PVZ).

The authors then blocked the activity of the periventricular zone, and the mice experienced longer fainting episodes. Stimulating the region caused the animals to wake up and start moving again. The team suggests that a coordinated neural network that includes NPY2R VSNs and the PVZ regulates fainting and recovery.

Lovelace, J. W. et al. Nature https://doi.org/10.1038/s41586-023-06680-7 (2023).

https://www.nature.com/articles/s41586-023-06680-7.epdf?sharing_tok...

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Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 9:33am

What causes fainting? Scientists finally have an answer

Mouse experiments reveal the brain–heart connections that cause us to lose consciousness rapidly — and wake up moments later.

Whether as a result of heat, hunger, standing for too long or merely the sight of blood or needles, 40% of people faint at least once in their lives.

But exactly what causes these brief losses of consciousness — which researchers call syncope — has been a mystery..

Now, researchers have discovered a neural pathway that controls the process, involving a group of sensory neurons that connect the heart to the brainstem. A study published in Nature on 1 November reports that activating these neurons made mice stop moving and fall over almost immediately, then display symptoms observed during human syncope, such as rapid pupil dilation and rolling eyes.

The authors suggest that this pathway holds the key to understanding fainting, beyond the long-standing observation that it results from reduced blood flow in the brain. There is blood-flow reduction, but, at the same time, there are dedicated circuits in the brain which manipulate this.

Using single-cell RNA sequencing analysis of the nodose ganglion, part of the vagus nerve (which connects the brain to several organs, including the heart), the team identified sensory neurons that express a type of receptor involved in the contraction of small muscles in blood vessels.

These neurons, called NPY2R VSNs, are distinct from other branches of the vagus nerve that connect to the lungs or the gut. Instead, they form branches in the lower, muscular parts of the heart, called the ventricles, and connect to a distinct area of the brainstem called the area postrema.

By combining high-resolution ultrasound imaging with optogenetics — a way of controlling neuronal activity using light — the researchers stimulated the NPY2R VSNs in mice while monitoring the animals’ heart rate, blood pressure, respiration and eye movements. This allowed the team to manipulate specific neurons and visualize the heart in real time.

When the NPY2R VSNs were activated, mice that had been moving around freely fainted in a few seconds. As well as showing rapid pupil dilation and eyes rolling back in their sockets, the mice demonstrated other symptoms of syncope in humans, including reduced heart rate, blood pressure, breathing rate and blood flow to the brain.

Humans usually recover rapidly from syncope. 

Part 2

Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 9:29am

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Mysteries of fainting revealed Experiments in mice have identified a specific group of sensory neurons that is responsible for syncope, the brief loss of consciousness during fainting. The cells — called NPY2R vagal sensory neurons — are found in the vagus nerve, which connects the brain to the heart and other organs. Scientists activated these cells in mice that were roaming about, which then fainted within a few seconds. Their pupils dilated, their eyes rolled back and their heart rate, blood pressure and breathing rate all dipped. The team also found that a region of the brain’s hypothalamus is responsible for recovery from fainting.
Part 1

Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 8:56am

Wildfire plumes deposit ash on seawater, fueling growth of phytoplankton

A team of marine biologists has found that large wildfires can deposit large amounts of ash on seawater, fueling the growth of phytoplankton. In their study, reported in the journal Proceedings of the Royal Society B: Biological Sciences, the group tested the impact of ash from a major wildfire on seawater samples in their lab.

Prior research has shown that large forest fires and wildfires produce a large amount of ash that remains in the air for a period of time before falling. Prior research has also found that when ash falls onto land, the result is usually positive—the ash serves as a form of fertilizer. Unfortunately, the same cannot be said for rivers and lakes—the sudden infusion of large amounts of toxic metals can kill fish and other aquatic creatures such as mollusks. For larger bodies of water, it can lead to algal blooms that remove oxygen from the water, resulting in dead zones. For this new study, the research team tracked wildfire plumes over the ocean. They collected samples of ash generated by the Thomas Fire in 2017 and brought them back to their lab for testing. The team mixed samples with fresh seawater in a jar. After a few days, they found that the ash/water solution contained high levels of dissolved nutrients, such as nitrogen and silicic acid. They found it also contained high levels of metals. The researchers then added more seawater to their ash/water solution that also contained microorganisms native to the ocean. They found that after several days, the number of microorganisms was twice as high as it was in a control sample of seawater. They also noted that they did not find any evidence that the ash had a toxic impact on the sea microorganisms. They suggest their work implies that wildfire plumes that settle on the ocean surface can lead to growth of phytoplankton communities.

T. M. Ladd et al, Food for all? Wildfire ash fuels growth of diverse eukaryotic plankton, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2023.1817

Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 8:43am

Research shows one sleepless night can rapidly reverse depression for several days

Most people who have pulled an all-nighter are all too familiar with that "tired and wired" feeling. Although the body is physically exhausted, the brain feels slap-happy, loopy and almost giddy.

Now neurobiologists are the first to uncover what produces this punch-drunk effect. In a new study, researchers induced mild, acute sleep deprivation in mice and then examined their behaviors and brain activity. Not only did dopamine release increase during the acute sleep loss period, synaptic plasticity also was enhanced—literally rewiring the brain to maintain the bubbly mood for the next few days.

These new findings could help researchers better understand how mood states transition naturally. It also could lead to a more complete understanding of how fast-acting antidepressants (like ketamine) work and help researchers identify previously unknown targets for new antidepressant medications.

Chronic sleep loss is well studied, and it's uniformly detrimental effects are widely documented and it is not good.Scientists long have known that acute perturbations in sleep are associated with altered mental states and behaviors. Alterations of sleep and circadian rhythms in patients, for example, can trigger mania or occasionally reverse depressive episodes.

 But brief sleep loss—like the equivalent of a student pulling an all-nighter before an exam—is less understood. Now researchers found that sleep loss induces a potent antidepressant effect and rewires the brain. This is an important reminder of how our casual activities, such as a sleepless night, can fundamentally alter the brain in as little as a few hours.

Mingzheng Wu et al, Dopamine pathways mediating affective state transitions after sleep loss, Neuron (2023). DOI: 10.1016/j.neuron.2023.10.002. www.cell.com/neuron/fulltext/S0896-6273(23)00758-4

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Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 8:25am

Biomimetic melanin heals skin injuries from sunburn and chemical burns

Melanin in humans and animals provides pigmentation to the skin, eyes and hair. The substance protects your cells from sun damage with increased pigmentation in response to sunlight—a process commonly referred to as tanning. That same pigment in your skin also naturally scavenges free radicals in response to damaging environmental pollution from industrial sources and automobile exhaust fumes.

Imagine a skin cream that heals damage occurring throughout the day when your skin is exposed to sunlight or environmental toxins. That's the potential of a synthetic, biomimetic melanin developed by scientists.

In a new study,  scientists show that their synthetic melanin, mimicking the natural melanin in human skin, can be applied topically to injured skin, where it accelerates wound healing. These effects occur both in the skin itself and systemically in the body. When applied in a cream, the synthetic melanin can protect skin from sun exposure and heals skin injured by sun damage or chemical burns, the scientists said.

The technology works by scavenging free radicals, which are produced by injured skin such as a sunburn. Left unchecked, free radical activity damages cells and ultimately may result in skin aging and skin cancer.

Topical Application of Synthetic Melanin Promotes Tissue Repair, npj Regenerative Medicine (2023).

Comment by Dr. Krishna Kumari Challa on November 2, 2023 at 11:44am

Scientists Just Discovered a New Human Sense of Touch

A new study reveals a previously undiscovered way that we can feel light touches: directly through our hair follicles. Before now, it was thought that only nerve endings in the skin and around the hair follicles could transmit the sensation.

Researchers used an RNA sequencing process to find that cells in part of the hair follicle called the outer root sheath (ORS) had a higher percentage of touch-sensitive receptors than equivalent cells in the skin.

From there, the researchers produced lab cultures of human hair follicle cells together with sensory nerves.

When the hair follicle cells were mechanically stimulated, the sensory nerves next to them were also activated – showing that touch had been registered.

The experiments also revealed that the neurotransmitters serotonin and histamine were being released by the ORS cells through tiny sacs called vesicles, as a way of signaling to the surrounding cells.

Touch-sensing nerve cells are known as mechanoreceptors. They're the reason we can feel everything from a light breeze to a firm press. In this case, the hair follicle cells were interacting specifically with low-threshold mechanoreceptors (LTMRs), capable of feeling gentle touches.

https://www.science.org/doi/10.1126/sciadv.adh3273

Comment by Dr. Krishna Kumari Challa on November 2, 2023 at 11:36am

How Could a Piece of the Moon Become a Near-Earth Asteroid? Researchers Have an Answer

A team of astronomers has found a new clue that a recently discovered near-Earth asteroid, Kamo`oalewa, might be a chunk of the moon. They hypothesized that the asteroid was ejected from the lunar surface during a meteorite strike–and they found that a rare pathway could have allowed Kamo`oalewa to get into orbit around the sun while remaining close to the orbits of the Earth and the Moon.

Comment by Dr. Krishna Kumari Challa on November 2, 2023 at 10:14am

In a fascinating paper authored by Toth and posted to the arXiv preprint server, he explores the possibility that multiple gravitational lenses might provide extra amplification of light to provide a communication bridge between distant civilizations.

In a conventional gravitational lens, a large mass—such as a cluster of galaxies—sits between a more distant object and the Earth. As the light travels from the distant object, it is bent around the galaxy cluster, providing a lensing effect to astronomers on Earth, allowing them to a) study the distribution of matter in the lensing cluster but also to observe the more distant object a little more easily. Toth proposes that, just like a conventional telescope that uses multiple lenses, a multiple gravitational lens could provide even more amplification than a single system.

Toth explores combinations of multiple gravitational lenses using a variety of methods but focuses (sorry) attention on a two-lens system (so-called gravitational lens bridge), which is aligned along the central axis of the system, but found no advantages and no additional signal amplification over the results from a single lens system. In addition, photon mapping techniques were applied with the same outcome; a double-lens system offers no advantage over a single-lens system.

Applying the wave theory of light to the same two-lens system revealed the same results, but using computer graphics to perform ray tracing (which cannot be used to estimate amplification) can help to highlight visual features other techniques would be unable to produce. Using this approach, it suggested a two-lens system would produce two concentric Einstein rings; however, they would be very difficult to detect in real-world scenarios. In summary, then, a fascinating concept, especially the possibility of using a lens bridge for communication with distant civilizations, but the results are less than promising. Yes, there may well be double gravitational lenses, but as this paper shows, it is unlikely we will be able to detect them for now and sadly I suspect the idea of using them as a long-distance cosmic telephone will for now remain science fiction.

 Viktor T. Toth, Non-coplanar gravitational lenses and the "communication bridge", arXiv (2023). DOI: 10.48550/arxiv.2310.15957

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