Dietary vitamin A (beta carotene) is not the active form of vitamin A (retinoic acid), it needs to be converted into the active form by the body's enzymes. Once retinoic acid is formed, it can bind to the retinoic acid receptor and regulate gene expression.

Retinoid treatment bypasses these enzymes and directly activates retinoic acid receptor signaling. So, eating vitamin A in the form of beta carotene won't directly increase retinoic acid receptor signaling because the rate-limiting step is the enzymes, but retinoid treatment will. This is also why you can't overdose on vitamin A by eating carrots.

Does this meet your criteria for a good answer? If not I can explain in more detail.

Lastly, you shouldn’t use Retinoids if you’re pregnant or likely to become pregnant.

This needs more emphasis. Retinoid signaling is very important for embryonic development, so excess retinoids will really mess up your baby. 

I agree with this. There's a lot of snake oil out there and cerebrolysin is just one example. I had no idea it was so popular though.

200 mg/day is a pretty high dose (at least for me)

Not just mammals, as far as I know it only works in E. coli bacteria and not in any eukaryotes.

Source:

https://www.nature.com/articles/s41586-024-07552-4

Interestingly there was just a similar article in the news section of Science, about glacier geoengineering.

https://www.science.org/content/article/avoid-sea-level-rise-some-researchers-want-build-barriers-around-world-s-most

>I'm using Quaise Energy as an example of a much larger overall trend - of the inability of investors to effectively evaluate technologies. The ability of investors to recognize good technical evaluations is the key thing that's lacking in the economy today; there are plenty of good ideas and there's plenty of investment capital.

Yeah, just look at Varda "manufacture drugs in space," and Colossal "bring back the wooly mammoth." It just doesn't make sense for these to be profitable businesses.

Reposting a comment from the Substack:

>Recently, he solved this problem!

I'm flattered, but I actually haven't gotten all the way to haploid cells yet. As I wrote in my preprint and associated blog post, right now I can get the cells to initiate meiosis and progress about 3/4 of the way through it (specifically, to the pachytene stage). I'm still working on getting all the way to haploid cells and I have a few potentially promising approaches for this.

Very cool. I wonder which University of Missouri lab the lentiviral plasmid leaked from...

I went a few times but eventually got grossed out by all the mold. (At least they don't sell live pangolins there.)