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Comment by Dr. Krishna Kumari Challa on August 14, 2021 at 9:38am

Scientists show how blocking opioid receptors in specific neurons can restore breathing during an overdose

Opioid overdose deaths are caused by disrupted breathing, but the actual mechanism by which these drugs suppress respiration was not understood. Now, a new study by  scientists has identified a group of neurons in the brainstem that plays a key role in this process.

The new findings show how triggering specific receptors in these neurons causes opioid-induced respiratory depression, or OIRD, the disrupted breathing that causes overdose deaths. It also shows how blocking these receptors can cause OIRD to be reversed.

Opioids work by binding to proteins on nerve cells (neurons) called opioid receptors and subsequently inhibiting their activity. Currently, naloxone is the only medication known to block the effects of opioids and reverse an overdose. But naloxone has limitations, including a short duration that requires it to be administered multiple times. It also works systemically, blocking opioid receptors throughout the entire body, including those that control pain.

In the new study, the researchers identified a group of neurons that express a certain type of opioid receptor (the mu opoid receptor) and are located in the brainstem breathing modulation center; they then characterized these neurons' role in OIRD.

They found that mice that were genetically engineered to lack opioid receptors in these neurons didn't have their breathing disrupted when exposed to morphine, as mice in the control group did. The researchers also found that, without introducing opioids, stimulating these receptors in control mice caused symptoms of OIRD.

The team then looked at ways to reverse the process by treating the overdosed mice with chemical compounds targeted to other receptors on the same neurons, which play an opposite role as the opioid receptor (activating rather than inhibiting them).

Shijia Liu et al, Neural basis of opioid-induced respiratory depression and its rescue, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2022134118

https://medicalxpress.com/news/2021-08-scientists-blocking-opioid-r...

Comment by Dr. Krishna Kumari Challa on August 13, 2021 at 7:42am

Antibodies Stop Sperm in Their Tracks

Engineered antibodies trap and immobilize human sperm in the reproductive tract of female sheep, paving the way for possible use as a nonhormonal contraceptive in people.

Currently, most available birth control options are barrier methods or rely on hormones to prevent fertilization of an egg—both of which have drawbacks, such as discomfort or side effects, that make them less than ideal for some people. Enter antisperm antibodies, described in a study published today (August 11) in Science Translational Medicine. Researchers generated antibodies that recognize an antigen unique to human sperm. When delivered topically to the reproductive tracts of sheep, the antibodies successfully bound and trapped more than 99.9 percent of introduced human sperm. Some of the authors have spun out a company, Mucommune, in order to continue the development of contraceptives based on these antibodies.

Previous work showed that some women’s bodies naturally produce antibodies to sperm that can lead to a type of immunological infertility. Lai’s group used the antigen binding fragment from one of these antibodies, which recognizes a sperm-specific antigen known as CD52g, in a study published in 2020, where they engineered an IgG antibody with four of the antigen-binding fragments and showed that it and the original, naturally-occurring IgG antibody with two antigen binding domains trapped sperm in vitro. 

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In the new study, Lai and colleagues added multiple antigen-binding fragments—6, 8, or 10—to an IgG antibody and then introduced expression plasmids into human embryonic kidney cells so the cells would produce them and researchers could isolate them. The team tested the antibodies’ ability to immobilize sperm in vitro, where the antibodies with extra antigen-binding fragments trapped sperm at least 10 times more effectively than the original IgG antibody with just two antigen-binding fragments. 

To explore the effects of the antibodies in vivo, the researchers introduced the original IgG antibody, one with 6 or 10 antigen-binding fragments, or saline into the vaginas of female sheep, which are similar to the human female reproductive tract, and then simulated intercourse and delivered a human semen sample. Two minutes later, they retrieved the sample and analyzed sperm movement. At a high dose (333 micrograms of antibody), all three antibodies tamped down nearly all sperm motility, and at a low dose (33.3 micrograms), both modified antibodies, but not the original IgG, trapped more than 90 percent of sperm.

https://stm.sciencemag.org/content/13/606/eabd5219

https://www.the-scientist.com/news-opinion/antibodies-stop-sperm-in...

Comment by Dr. Krishna Kumari Challa on August 13, 2021 at 7:10am

Newtonian physics for babies

Comment by Dr. Krishna Kumari Challa on August 13, 2021 at 6:34am

Combining classical and quantum systems to meet supercomputing demands

Quantum entanglement is one of the most fundamental and intriguing phenomena in nature. Recent research on entanglement has proven to be a valuable resource for quantum communication and information processing. Now, scientists from Japan have discovered a stable quantum entangled state of two protons on a silicon surface, opening doors to an organic union of classical and quantum computing platforms and potentially strengthening the future of quantum technology.

One of the most interesting phenomena in quantum mechanics is "quantum entanglement." This phenomenon describes how certain particles are inextricably linked, such that their states can only be described with reference to each other. This particle interaction also forms the basis of quantum computing. And this is why, in recent years, physicists have looked for techniques to generate entanglement. However, these techniques confront a number of engineering hurdles, including limitations in creating large number of "qubits" (quantum bits, the basic unit of quantum information), the need to maintain extremely low temperatures (<1 K), and the use of ultrapure materials. Surfaces or interfaces are crucial in the formation of quantum entanglement. Unfortunately, electrons confined to surfaces are prone to "decoherence," a condition in which there is no defined phase relationship between the two distinct states. Thus, to obtain stable, coherent qubits, the spin states of surface atoms (or equivalently, protons) must be determined.

Recently, a team of scientists  recognized the need for stable qubits. By looking at the surface spin states, the scientists discovered an entangled pair of protons on the surface of a silicon nanocrystal.

Proton entanglement has been previously observed in molecular hydrogen and plays an important role in a variety of scientific disciplines. However, the entangled state was found in gas or liquid phases only. Now, researchers have detected quantum entanglement on a solid surface, which can lay the groundwork for future quantum technologies.

The scientists studied the spin states using a technique known as "inelastic neutron scattering spectroscopy" to determine the nature of surface vibrations. By modeling these surface atoms as "harmonic oscillators," they showed anti-symmetry of protons. Since the protons were identical (or indistinguishable), the oscillator model restricted their possible spin states, resulting in strong entanglement. Compared to the proton entanglement in molecular hydrogen, the entanglement harbored a massive energy difference between its states, ensuring its longevity and stability. Additionally, the scientists theoretically demonstrated a cascade transition of terahertz entangled photon pairs using the proton entanglement.

Takahiro Matsumoto et al, Quantum proton entanglement on a nanocrystalline silicon surface, Physical Review B (2021). DOI: 10.1103/PhysRevB.103.245401

https://phys.org/news/2021-08-worlds-combining-classical-quantum-su...

Comment by Dr. Krishna Kumari Challa on August 13, 2021 at 6:21am

Dendrimers: The tiny tentacles shown to evade our immune response

Tiny synthetic particles known as dendrimers avoid detection by our immune system and could help develop a new way to deliver drugs into the body without triggering a reaction.

The dendrimer is a chemically-created molecule with tentacles branching out in a highly-symmetrical structure around a central core. The research describes how dendrimer tentacles arranged incredibly closely to each other—less than one nanometer apart—avoided detection by the complement system, part of our immune system.

Our immune system is equipped with many tools to recognize and eliminate invaders. For example, our blood contains sensors belonging to a family of defense system known as the "complement system," which recognizes unique patterns expressed by invaders such as bacteria and viruses. Binding of these sensors to pathogens alarms the immune system and triggers an immune response. These sensors are termed "complement pattern-recognition (CPR)" molecules.

CPR can sense surface patterns that are regularly repeated so close to each other, for instance in 2–15 nanometer ranges—a distance, which is at least 5000 times thinner than the thickness of a typical sheet of paper.

The international team discovered however, that the CPR could not sense patterns repeated closer to each other, for instance, at 1 nanometer or less.

At a nanoscale level, the team grew tiny particles known as dendrimers which are shaped like trees with many branches—or tiny tentacles. The number of tentacles exponentially increases with dendrimer size and the tentacles are positioned less than 1 nanometer from each other. The ends of tentacles are where regular patterns appear. Depending on chemical structure of these patterns, they found that these dendrimers could escape detection by the CPR radar.

Dendrimers offer us the ability to deliver drugs to diseased sites where inflammation is a major problem such as in conditions like atherosclerosis, cancer, macular degeneration  and rheumatoid arthritis.

Lin-Ping Wu et al, Dendrimer end-terminal motif-dependent evasion of human complement and complement activation through IgM hitchhiking, Nature Communications (2021). DOI: 10.1038/s41467-021-24960-6

https://phys.org/news/2021-08-dendrimers-tiny-tentacles-shown-evade...

Comment by Dr. Krishna Kumari Challa on August 12, 2021 at 1:05pm

Can you Stand On Liquid Mercury?

Comment by Dr. Krishna Kumari Challa on August 12, 2021 at 11:46am

At the ions' relativistic speeds, the virtual particles can behave like real photons. Thankfully, there's a way physicists can tell which electron-positron pairs are generated by the Breit-Wheeler process: the angles between the electron and the positron in the pair generated by the collision.

Each type of collision - virtual-virtual, virtual-real and real-real - can be identified based on the angle between the two particles produced. So the researchers detected and analyzed the angles of over 6,000 electron-positron pairs generated during their experiment.

They found that the angles were consistent with collisions between real photons - the Breit-Wheeler process in action.

"We also measured all the energy, mass distributions, and quantum numbers of the systems. They are consistent with theory calculations for what would happen with real photons.

"Our results provide clear evidence of direct, one-step creation of matter-antimatter pairs from collisions of light as originally predicted by Breit and Wheeler."

The argument could be very reasonably made that we won't have a direct first detection of the pure, single photon-photon Breit-Wheeler process until we collide photons approaching the energy of gamma rays.

Nevertheless, the team's work is highly compelling stuff - at the very least, it shows that we are barking up the right tree with Breit and Wheeler.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.052302

Part 3

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Comment by Dr. Krishna Kumari Challa on August 12, 2021 at 11:45am

At the RHIC, ions are accelerated to relativistic speeds - those that are a significant percentage of the speed of light. In this experiment, the gold ions were accelerated to 99.995 percent of light speed.

This is where the magic happens: When two ions just miss each other, their two clouds of photons can interact, and collide. The collisions themselves can't be detected, but the electron-positron pairs that result can.

However, it's not enough to just detect an electron-positron pair, either.

That's because the photons produced by the electromagnetic interaction are virtual photons, popping briefly in and out of existence, and without the same mass as their 'real' counterparts.

To be a true Breit-Wheeler process, two real photons need to collide - not two virtual photons, nor a virtual and a real photon.

part 2

Comment by Dr. Krishna Kumari Challa on August 12, 2021 at 11:45am

Physicists Detect Strongest Evidence Yet of Matter Generated by Collisions of Light

According to theory, if you smash two photons together hard enough, you can generate matter: an electron-positron pair, the conversion of light to mass as per Einstein's theory of special relativity.

It's called the Breit-Wheeler process, first laid out by Gregory Breit and John A. Wheeler in 1934, and we have very good reason to believe it would work.

But direct observation of the pure phenomenon involving just two photons has remained elusive, mainly because the photons need to be extremely energetic (i.e. gamma rays) and we don't have the technology yet to build a gamma-ray laser.

Now, physicists at Brookhaven National Laboratory say they've found a way around this stumbling block using the facility's Relativistic Heavy Ion Collider (RHIC) - resulting in a direct observation of the Breit-Wheeler process in action.

But what do accelerated ions have to do with photon collisions? Well, we can explain.

The process involves, as the collider's name suggests, accelerating ions - atomic nuclei stripped of their electrons. Because electrons have a negative charge and protons (within the nucleus) have a positive one, stripping it leaves the nucleus with a positive charge. The heavier the element, the more protons it has, and the stronger the positive charge of the resulting ion.

The team used gold ions, which contain 79 protons, and a powerful charge. When gold ions are accelerated to very high speeds, they generate a circular magnetic field that can be as powerful as the perpendicular electric field in the collider. Where they intersect, these equal fields can produce electromagnetic particles, or photons.

"So, when the ions are moving close to the speed of light, there are a bunch of photons surrounding the gold nucleus, traveling with it like a cloud.

part 1

Comment by Dr. Krishna Kumari Challa on August 12, 2021 at 11:38am

The 'Second Brain' in Your Gut Might Have Evolved Before The Brain in Your Head
The enteric nervous system (ENS) in our gut operates a lot like other neural networks in the brain and the spinal cord – so much so that it's often called the 'second brain'. Now a new study has revealed more about how exactly the ENS works.
Using a recently developed technique combining high-resolution video recordings with an analysis of biological electrical activity, scientists were able to study the colons of mice, and in particular the way that the gut moves its contents along.

One of the key findings was discovering how the thousands of neurons inside the ENS communicate with each other, causing contractions in the gastrointestinal tract to aid the digestive process. Up until now, it wasn't clear how these neurons were able to join forces to do this.

"Interestingly, the same neural circuit was activated during both propulsive and non-propulsive contractions.

The team found large bunches of connecting neurons firing to propel the contents of the colon further down the gut, via both excitatory (causing action) and inhibitory (blocking action) motor neurons.

The discovery means the ENS is made up of a more advanced network of circuitry, covering a wider section of the gut and involving a greater amount of different types of neurons working in tandem than had previously been thought.

Another important finding is that this activity is significantly different from the propulsion that's seen in other muscle organs around the body that don't have a built-in nervous system, such as lymphatic vessels, ureters, or the portal vein.

"The mechanism identified is more complex than expected and vastly different from fluid propulsion along other hollow smooth muscle organs," the researchers explain in their paper.

The team says it backs up the hypothesis that the ENS is in fact the 'first brain' rather than the second one – suggesting that it may have evolved in animals a long time before our actual brains took their current form.

https://www.nature.com/articles/s42003-021-02485-4

https://www.sciencealert.com/we-have-a-brain-like-system-in-our-gut...

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