eSagan 🇮🇳 @crackurbones@qoto.org
Joined Nov 2019
Major #Greenland glacier collapse 90 years ago linked to #climatechange https://t.co/uLTMS6foPk
https://twitter.com/physorg_com/status/1237744019012300801?s=09
#Microbes could influence your desire to get outside
https://t.co/wnIZEYUCmW
https://twitter.com/medical_xpress/status/1237744128731090944?s=09
🌱 AMAZING Small Farm in France Under TREES! // Aromath Farm
https://www.youtube.com/watch?v=HAZwj23DxVE
We May Have Finally Found a Chunk of Theia Buried Deep Inside The Moon
https://www.sciencealert.com/we-may-have-finally-found-a-chunk-of-theia-buried-deep-inside-the-moon
The Fastest Supercomputer on Earth Is Being Deployed Against Coronavirus - ExtremeTech
https://www.extremetech.com/computing/307381-the-fastest-supercomputer-on-earth-is-being-deployed-against-coronavirus
The US Department of Energy has announced that the Summit supercomputer will be used to attempt to find a treatment or cure for Covid-19.
🔸 Between two neurons lie the pre-synaptic cell and the post-synaptic cell (cells with the synaptic terminal). They are separated by a short distance called the 'synaptic cleft'.
And the molecules of nerve transmitter are going to make their way from pre-synaptic cell to post-synaptic cell through the synaptic cleft.
🔸 Neurotransmitters need to have a termination, if they are not received by the post-synaptic cell. We use three different mechanisms to terminate the message of a neurotransmitter.
1️⃣ Diffusion: The molecules are simply going to diffuse out if they don't make it to the "ears" of post-synaptic terminal of the receiving neuron. So diffusion is a very effective way to terminate a message.
2️⃣ The second way is through something called re-uptake. And re-uptake is typically in the pre-synaptic terminal. There are channels, or transporters, which take neurotransmitters back up. The neurotransmitters get re-packaged and put back into a new vesicles (which are actually recycled as well).
🔸 And this is really important for drugs like #serotonin and #dopamine. And there are drugs that act on the serotonin and dopamine re-uptake transporters that can be used both therapeutically, for instance, to treat depression.
3️⃣ The third way that we terminate a message is through degradation. And in the case of degradation, what we have is enzymes that sit in the synaptic cleft that are just chewing up neurotransmitters. [GIF]
🔸 The molecule that the neurotransmitter where degradation is really important is #acetylcholine.
So, in case of acetylcholine, there is an enzyme that sits between the pre-synaptic and the post-synaptic cells, eating up acetylcholine, called acetylcholinesterase (AChE).
🔸 Acetylcholine is the neurotransmitter that is used by motor neurons. And so, in fact, blocking #acetylcholinesterase can be used for therapeutics — in the case of people that are not releasing enough acetylcholine, or don't have enough receptors for the acetylcholine.
🔸 We can boost the amount of acetylcholine in the cleft by inhibiting the acetylcholinesterase. And that's useful for people with diseases such as myasthenia gravis.
Clostridial Toxins: #Botox
🔸 Botox is one of several clostridial toxins made by clostridial bacteria. And the full name of Botox is actually botulinum toxin.
🔸 The vesicles are held very close to the cell membrane. What holds them? A group of three proteins, two of them anchored in the cell membrane, one of them anchored in the vesicle membrane. This complex is called the snare complex.
🔸 And what happens when calcium comes in is that it changes snare complex's shape. Ca²⁺ changes snare's configuration to being in a straight line. [see GIF]
🔸 So that pushes the vesicle into the plasma membrane and fusion Is inevitable. It takes a lot of energy for them not to fuse, and when they're that close, it's inevitable.
🔸 It's the snare pin's sensitivity to calcium that is the final event that allows the vesicle to fuse with the cell membrane.
🔸 Botox comes in and cuts a particular protein of these proteins of the snare pin. But the clostridial toxins cut a variety of places in these three proteins that make up the snare pin.
🔸 If the snare pin is broken for whatever reason, if that is cut, then release doesn't happen.
🔸 Nowadays, we use clostridial toxins all the time — and we use them for very serious problems, such as focal dystonia, where there is an inappropriate continual contraction of a muscle, and that is a basal ganglia disorder.
💉 So, the Botox is injected at a very low dose, very locally.
And Botox is used for a large variety of treatments of various disorders. It's also used cosmetically.
🔸 And the interesting thing about it's use in cosmetics is that, before the widespread use of Botox, we made our own wrinkles. And what Botox is doing is preventing the motor neuron from releasing the neurotransmitter on to the muscle, and thereby preventing us from actively making our own wrinkles.
Babies who persistently struggle with sleep in their first year are more likely to have childhood anxiety https://t.co/ViVdRLX0Fc
https://twitter.com/MailOnline/status/1237593795010543618?s=09
New Intelligence on How the Female Brain Works - WSJ
https://www.wsj.com/articles/what-makes-the-female-brain-different-11583528929
The brain regions affected by declines in #estrogen during #menopause include the hypothalamus, which regulates body temperature; the brain stem, which regulates sleep and stress; the hippocampus, or memory center; and the amygdala, which is the emotional center of the brain.
🔸 How do we get the neurotransmitter out of the vesicle and out of the cell and make it able to go and affect another cell?
🔸 There is a cell membrane, but the cell also has a lot of other membranes that are inside. Inside in these things called organelles.
🔸 The fusion between two different membranes happens constitutively. And the challenge for a neuron is to stop that.
We can't have these vesicles fusing with the plasma membrane, with the cell membrane all the time. That would not work.
🔸 What we want to do is we want to make the vesicle fuse to the membrane **only when the action potential arrives** .
🔸 So the key to neurotransmitter release is two things:
1. We're going to suppress constitutive or ongoing release.
2. We are going to link the release that we want in the synaptic terminal to the action potential.
🔸 There is a molecule that suppresses constitutive release within the synaptic terminal.
🔸 When the action potential comes in, the membrane potential increases and it opens a particular type of ion channel that lets in calcium ions.
🔸 These are positively charged ions with two positive charges. And, these calcium ions are going to flood in to the synaptic terminal, and that is going to trigger release.
🔸 The release that happens of vesicles that contain neurotransmitters is only when the calcium concentration increases.
🔸 All that happens when the calcium concentration increases is that the vesicular membrane and the the cell membrane fuse.
And the calcium concentration only increases when the action potential arrives.
🖼️ Image source: screen-grab from https://www.coursera.org/learn/neurobiology/lecture/o4ZMY/neurotransmitter-release
The WALKING WATER Mystery (in SPACE and SLOW MOTION!) - Smarter Every Day 160
https://www.youtube.com/watch?v=KJDEsAy9RyM
🌱 ECO HOME: No Power, Water & Sewer connection in this house.
https://www.youtube.com/watch?v=LB5gzj0bmq0
New model is very good at predicting the charging time of a supercapacitor while also incorporating physics on the micro and nano scales. https://t.co/N7xGGWI81a
https://twitter.com/PhysicsWorld/status/1237389694918250496?s=09
🧫 The synaptic terminal has these entities here, which are called synaptic vesicles, and they're small, little organelles.
🧫 They're little vesicles made of a membrane; just like the cell has a cell membrane, these vesicles have a vesicular membrane.
The neurotransmitters are within the vesicular membrane.
🧫 And, the neurotransmitter can be any number of a number of different molecules — #Glutamate, #GABA, #Serotonin, #Dopamine, #Acetylcholine, #Glycine, #Norepinephrine, #Epinephrine, #Histamine, #ATP.
🧫 The neurotransmitters are packaged in vesicles. The second thing that's important about this is that we can use the synthesis of a #neurotransmitter as a therapeutic tool.
🧫 So, for instance, Dopamine is missing in #ParkinsonsDisease.
It's not that dopamine isn't made per say, that's there's a problem with making it — it's that the cells that make it die.
🧫 There's something called 'Mass Effect', which means that you take the starting chemical (the substrate) and then through a series of enzymatic processes reaction, through a series of enzymatic reactions, we end up with a neurotransmitter.
🧫 In the case of Dopamine, what we do to treat in most people with Parkinson's is that we give them the substrate — and so that (drug) is what is commonly known as #Sinemet or #Parcopa.
🧫 So we flood the system with substrate, and the goal is to get a little bit of that neurotransmitter out of the system.
Image source: https://in.pinterest.com/pin/11962755239342046/?lp=true
Machine learning illuminates material's hidden order
https://phys.org/news/2020-03-machine-illuminates-material-hidden.html
Extreme temperature can do strange things to metals. In severe heat, iron ceases to be magnetic. In devastating cold, lead becomes a superconductor.
The case for an AI that puts nature and ethics first, not humans
https://thenextweb.com/neural/2020/03/07/the-case-for-an-ai-that-puts-nature-and-ethics-first-not-humans-syndication/
Without Facebook and Twitter, This is How Organisms Stayed Connected Billions of Years Ago
https://www.news18.com/news/buzz/without-facebook-and-twitter-this-is-how-organisms-stayed-connected-billions-of-years-ago-2530549.html
⚡ Neurons sit at a resting membrane potential of about -65 mV.
⚡ Small little potential differences — which are on the order of less than one millivolt up to, say, five millivolts — can travel along the neuron.
⚡ They might travel, but they're going to peter out pretty quickly. So, it's not going to work to simply rely on these small potential changes if we have to go long distances.
⚡ The longest neuron that we possess is a cell that has a cell body right at the base of the spine. And it sends one process all the way down to the toe, and it sends another process all the way up to the medulla.
⚡ Because neurons are so long, we use something called the Action Potential. And the Action Potential goes really far up and comes back down in height. So, it's about 100 mV.
⚡ So from the resting memory potential (-65mV) to the top of the Action Potential — which happens at around, say, 20mVs or so — we're talking about roughly 100 millivolts of difference. And that can get communicated all the way up. That's not going to get lost.
⚡ And what carries that Action Potential is: —
We looked at potassium being in very high concentration in a cell and much lower outside a cell. The reverse is true for sodium.
And so, the sodium comes flooding in, and because it's positively charged, that's what takes the cell up to this very high membrane potential.
⚡ Now the ability for a neuron to communicate using an Action Potential is a slow process unless we add one more thing, and that is an insulator —essentially a very nice insulator —called myelin.
⚡ Electrical language of cells ⚡
⚛️ In a living organism, we don't use electrons. Instead, we use molecules that have a charge, and those molecules are called ions.
⚛️ So these ions are present within the context of cells. And all cells have what are called cellular membranes, which are made up mostly of fat. It's important to understand that most of a membrane is fat. And this is like a layer of oil surrounded by a couple layers of water.
⚛️ Let's consider an ion that's positively charged, and let's consider one to be potassium ion (K+).
⚛️ This potassium ion is very happy in water, but it can't get through oil. It's not gonna pass through there. So it's gonna bounce off this membrane. And the only way for it to get through is via a special place which we're gonna call an ion channel.
⚛️ The physical force for this potassium ion is to leave the cell because of lower concentration of ions outside the cell than in the cell (osmosis).
But, on the other hand, the cell is actually negatively charged. And outside the cell is grounded.
⚛️ The potassium ion is positive and so there's an electrical force that attracts it into the cell.
⚛️ The potential at which the physical (osmotic) force and the electrical force will be equal is where the membrane is gonna sit.
⚛️ And we have to worry about three ions -- the potassium ion, the sodium ion, which is also positively charged, and chloride ion. And once we take into consideration each of these ions, what we see is that this cell is going to sit at rest at about -70 to -60 millivolts (with respect to the potential outside the cell).
Joined Nov 2019
