They’re not miracle cures, sensational titles are made to gain clicks. I’d recommend reading the articles if you have the time.

That being said, I do believe they have therapeutic benefits when used alongside therapy. I’m going to excuse ketamine as a psychedelic and focus on MDMA and mushrooms (psilocybin). If you have taken MDMA or Mushrooms you may have experienced a rush of love and beauty in the world. Mushrooms especially make me want to call friends and family to tell them how much I love them. When I think about personal problems in my life on these substances, I think very matter of fact. This happened and it’s okay to feel sad. This happened and I can improve my situation by doing such and such. I’m embarrassed about something and that’s fine, it’s human to be embarrassed.

I’ve read an article suggesting the brain “rewires” itself when on these drugs. When someone with PTSD experiences a triggering event while high on these drugs AND they’ve been given proper tools to deal with their stressors, the person may not react as extreme as they had previously. Not reacting to something is improvement and can help the person be ready for a triggering event in the future. I don’t think it’s a miracle, just something that helps push you to get past your problems.

If you are anxious about something the best thing to do is force yourself to deal with it. Worried about socializing? Go socialize. Scared of talking about personal issues? Talk about them. The more practice you have doing something the easier it becomes.

>Actually, when you're at the scale of these molecular interactions, the concepts of rigidity hold up pretty nicely. (BTW, the broadest term for these kinds of interactions can be called "ligand-receptor binding", and the "lock-and-key" model works well for describing it.

That is not true. The lock and key model is known to be less correct than models such as induced fit or conformational selection.

It's like i learned more.. but know less?

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The program was supposed to be a drop in replacement upgrade. When they realized they would need to start making serious changes to fasteners and other equipment they just killed the entire thing. The changes they would of had to make were far outside the scope of their original intent and they were basically out of project money.

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From that paper “The mechanism of action of semaglutide in patients with obesity is similar to that of liraglutide — primarily energy intake reduction — but semaglutide has also been shown to improve control of eating and food cravings and reduce preference for fatty, energy-dense foods (6), suggesting that semaglutide may affect food intake via hedonic as well as homeostatic pathways.”

So it does not just make you eat less. You know when you eat so much fatty food at one point you’re like i cant anymore or crave something light. That signalling is mimicked my semaglutide.

Also your body reacts to hunger by shutting down, so you start burning less and you plateau. This does not happen if instead of hunger you feel full. Semaglutide slows the food passing through you so you feel full.

One more thing…these drugs CAN and WILL interact with prescription medication. Some of these interactions can be fatal. Serotonin syndrome is extremely common and extremely fatal. Don’t mix drugs unless you know for a fact that it is safe to do so.

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Basic answer is yes it can. The original superconductor was mercury, which had to be distilled before it could be pure enough to go superconductive.

This is covered in this very informative discussion from BBC radio.

I hope this is available in your area. This series is great for curious people wanting to learn about many subjects.

Proteins can* be very rigid, and that rigidity comes mostly from four forces:

• hydrophobic and hydrophilic interactions (some amino acids will stay away from water and twist to the inside of the protein, others will be attracted to the water and be on the outside of the protein)

• hydrogen bonding in the protein (some substituents make strong dipole interactions with each other, these forces also exist in the backbone of the protein, making sub-structures)

• electrostatic interactions (parts of the protein carry positive and negative charges, which help hold the protein together)

• disulfide bridges formed from two cysteines which are actual covalent bonds between two parts of the chain

Here's the important part: when something binds to the protein, the electrical and chemical environment around the protein changes, and the protein will* change shape. For example, if a signal peptide with a lot of charged side chains lands on the receptor site, amino acids with charged side chains in the receptor will try to twist towards or away from it. This will change the shape of the protein, potentially opening new receptor sites or setting off other signalling.

A great example is this animation of a G-protein coupled receptor. Watch it change shape as things bind and unbind to it (the good part starts at 4:15) https://youtu.be/ZmrDWIeX0Tc

*Per /u/danby, below, the hydrogen bonding network is quite flexible, so we can't really call the protein a rigid body.

*Again, per /u/danby, there are examples of binding without structural change.

Often you will get a conformational change in the receptor upon agonist/antagonist binding. So, the bound compound changes the electron distribution of the receptor just enough that it's more stable in another state. For AMPA receptors, for example, they're composed of 4 proteins that form, like, columns through a cell membrane. When it's not activated, the 4 proteins are slightly twisted, such that there is no opening between them. With each glutamate that binds, the proteins that make up the AMPA receptor twist slightly, exposing an opening down the middle. The more open the receptor, the more ions can flow through the channel. When an antagonist binds, the quaternary structure of the AMPA receptor is more stable in a deactivated state, even if more glutamate bind. These bindings are typically transitory, so the molecule will kind of "flicker" on and off the receptor, but when concentrations are high, it's more likely to be bound, and when concentrations are low, it's less likely to be bound.

TL;DR: It's about electron charge distributions.

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Thanks for the answer!

In short, when the ligand (can be peptides, drugs, proteins, etc.) binds to receptor, the said receptor will change its form ("conformational change") and allowing some kinds of actions, i.e. opening ion channel, releasing some kinds of intracellular molecules (second messenger system), increasing/decreasing transcription of some genes, etc.

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Some ligands can be highly specific to its receptor, but some ligands may act at many different receptors. The ligands can bind irreversibly or reversibly, allowing different duration of action and concentrations affecting how the receptor works. Some ligands may also compete for same space of receptor, allowing it to act in dose-dependent manner.

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References:

1. Katzung BG. Basic and Clinical Pharmacology. 14th ed. New York: McGraw Hill Education; 2018.

2. Whalen. Lippincott Illustrated Reviews: Pharmacology (Lippincott Illustrated Reviews Series) SEVENTH EDITION. Vol. 53, Journal of Chemical Information and Modeling. 2019.

Receptors are proteins, which are made up of amino acids that fold into a particular 3-dimensional shape. Different amino acids can also have different properties such as positive and negative charges, hydrophobic or hydrophilic side chains, etc.

Receptors can also be modified with sugars, lipids, etc. but the ligand binding site is usually just amino acids.

When a ligand (protein or other molecule) binds to the receptor, it will interact with the amino acids in the binding site, based on their 3D shape and physical properties (charge, hydrogen bonding, etc.) The binding affinity of the ligand will depend on how strongly it interacts with the binding site. This is how the receptors establish selectivity for binding some molecules instead of others.

You can think of the binding event like a hand fitting into a glove. The glove will change shape a bit when the hand goes into it. This conformational change in the receptor can cause downstream biological effects, depending on the function of the receptor. Many receptors are kinases which phosphorylate proteins when the ligand is bound.

Also, some inhibitors (called competitive inhibitors) will bind to the receptor and not cause conformational changes like the normal ligand, but still occupy the binding site.

Regarding the question of rigidity/solidity, proteins can be more or less flexible (depending on the protein) but the individual bonds are pretty rigid, and most receptors will have only a few stable conformations.

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How can you prove anything is zero? Even for the photon mass the best we have is an upper limit of 10^-18 ev/c^2.

It comes from huygens principle. Each point of a wavefront can be treated as a point source for a wavefront. They seems to form a common wavefront because they interact with each other through a phenomenon called interference.

This leads to a wave entering into a lower impedence media to be refracted away from the normal of the surface, you can view it as a car which comes from driving in mud into driving on good ground with one wheel first, that wheel will get better traction and the car will turn as it is now moving faster than the other wheel. At a certain angle the car will turns so much that the other wheel never passes the boundary, the car is deflected.

You could see it as the first wheel being a part of the wavefront which passes the boundary then starts interfering with the wave point sources still inside the media causing the aggregate wave front to not pass the boundary. Maye one could say that they interfere with their own potential to travel faster beyond the boundary.

Sound is not my speciality though I'm more used to thinking probablity waves so someone else may have a better explanation. But it should work the same, all waves act in the same way.

Edit: Also something about the energy being indestuctible and dependent on the frequency (which means the frequency cannot change) and the sound moving quicker and/or slower which means that the wavelength change in diffrent media. It's been almost ten years since I worked with waves.

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Actually, when you're at the scale of these molecular interactions, the concepts of rigidity hold up pretty nicely. (BTW, the broadest term for these kinds of interactions can be called "ligand-receptor binding", and the "lock-and-key" model works well for describing it. The ligand (or soluble protein) binds specifically to its receptor with high affinity. The subsequent steps are analogous to the mechanism within a lock when the key is turned. The altered structure of the receptor causes a change in another molecule (e.g., a "kinase" enzyme), which in turn induces a conformation change in another molecule. Subsequent interactions can result in a cascade of changes that result in the cell changing in some way (e.g., secreting a hormone or altering the voltage potential across its membrane).