• 29 Posts
  • 15 Comments
Joined 1 year ago
cake
Cake day: June 13th, 2023

help-circle










  • I think that @[email protected] provided a great response for the specific case of flow in a pipe.

    I just want to add that if you look beyond the restrictions of flow in a pipe, there are many other types of behavior that non-Newtonian fluids exhibit. We measure this in the lab on instruments called rheometers. Basically, we put some liquid in the instrument and then deform it and measure the resistance to that deformation. One of the most common ways to apply that deformation is to do so back and forth in an oscillating manner. Depending on the frequency at which you apply this strain, the solid/liquid-like behavior can change. If you have some background in physics or want to get a decent understanding, I found this paper that, on skimming it, seems to be pretty consistent with the way I was taught this stuff in grad school.

    One graph I want to point out is Figure 13 which shows what would be a “typical” viscoelastic polymer solution. An easy way to understand this graph is that as we go from left to right, we are applying strain back and forth quicker and quicker, essentially shaking it faster. When the G’ value is higher than the G" value, then the material is behaving more like a solid and conversely, when G" > G’, then it is behaving more like a liquid. You can see that the material goes through different phases of behavior as the strain frequency changes. Just for you I went and dug up an old graph from my thesis to show a real-life example of this happening too.

    My favorite demonstration of this is to put Oobleck (or something similar) onto a speaker and then change the frequency and see what happens.







  • That’s fair. I couldn’t find much info on their website, so I assumed this was another make insulin cheap using “biohacking” deal. I don’t have any experience with small molecule synthesis or dry powder manufacturing, so I can’t really speak to how feasible this may be. However, having seen first-hand all the ways simple manufacturing steps can go wrong, the risk of consuming a medication that hasn’t been through rigorous QA/QC makes me very wary.


  • Apologies for the long post. I don’t mean this as an attack on OP, just trying to illustrate why actually doing this is a bad idea.

    I have seen efforts like this in the past, especially centered around efforts to manufacture insulin cheaply. While I get that medicine cost and availability is broken at a fundamental level in the US, the solution is a political one rather than to run a wildcat bioreactor. There is simply no way to safely manufacture biologics using a 3d printed bioreactor. Let’s look at the manufacturing process to get an idea of why.

    Staring with the bioreactor, you would need some way to sterilize it before use (not just sanitize, there’s a difference). There are plastic bioreactors that are used in industry, but they are large, single-use bags that are sterilized using gamma or x-ray radiation. Most industry bioreactors are made of stainless steel to withstand the harsh treatment required to re-sterilize them (steam or hydrogen peroxide).

    Moving down the chain from the bioreactor, you need some way to remove your product from the harvested liquid. This is usually done through lysing the cells you have grown and then running this lysate through a series of chromatography columns of varying types (affinity, ionic, etc.) to systematically remove all the junk left over from your cellular media and the cells you have lysed. Even if you could (unsafely) grow your cells and drug in a 3d printed bioreactor, you don’t have these kinds of things at home and can’t just get them from Amazon.

    However, let’s say that you could get past the purification step, what’s next? You find yourself with a large volume of very dilute medicine suspended in a chromatography buffer. The next step is what is called UF/DF, or ultra-filtration/dia-filtration. This step, paradoxically done DF first, uses filter membranes and large amounts of buffer and some pressure to first swap out the buffer that your medicine is in to the target formulation that you want to inject and then concentrate it down to a manageable volume. If you are working at small scale, then you can probably replace this step with just one filter and a centrifuge. Remember that while you are doing all this, everything that comes into contact with your drug needs to be sterile (even the air).

    I think I have made my point, but for actual drugs there are more steps beyond this. Post-UF/DF is what is referred to as drug substance (DS) in the industry. You still need to go through a sterile fill-finish process to get drug product (DP) that is what is actually given to a patient. If you really want, I can go on another long tirade here since this is the step my job focuses on.

    I have worked on these manufacturing processes and seen them fail a lot for very hard to catch problems. Without all the in-process controls and testing we do, there would have been serious risks of giving bad DP to patients. If you have read this far, then I hope I’ve convinced you not to give this kind of thing a try.

    The real problem this is trying to solve is a political one. We should be advocating for better access to medications and reforming how costs are dealt with. It doesn’t matter what your political persuasion is, I think everyone agrees healthcare in the US is broken and it’s time something is done about it.





  • wjs018@beehaw.orgtoScience@beehaw.orgmRNA Vaccine Science
    link
    fedilink
    English
    arrow-up
    4
    ·
    1 year ago

    It hopefully should. One of the main reasons biologics are so expensive isn’t just corporate greed (though it is that too), but because the manufacturing process is very intense. Running bioreactors at commercial scale to make your product, using a train of chromatography steps to purify it, and then filtering it to be concentrated and sterile before fill/finish in a pre-filled syringe or vial followed sometimes by lyophilization is an insanely complicated process that is very costly. mRNA processes simplify this a lot in that the mRNA don’t need to be manufactured using bioreactors that are filled with dirty cellular flotsam and jetsam that need removed. So, the production and purification parts are much much simpler. It still isn’t likely to be cheap, as GMP manufacturing is still complex and the fill/finish part of the operations are largely unchanged, but hopefully cheaper.




  • wjs018@beehaw.orgtoScience@beehaw.orgmRNA Vaccine Science
    link
    fedilink
    English
    arrow-up
    8
    ·
    1 year ago

    I work in this field and this is a great summary of mRNA and its therapeutic usage. The article does mention it, but mRNA is going to be widely used beyond vaccines as well.

    As an example, at a previous company I worked at that had a robust pipeline and a portfolio of antibodies on the market, they were actively developing an mRNA-LNP version of all of their mAb programs. The idea is that if you develop an LNP platform that can reproducibly transfect say, the liver, then you can just turn the liver into a protein factory for anything you provide the mRNA sequence for. Having mAbs produced and excreted in the body solves one of the big challenges to convenient biologics dosing, bioavailability. Basically, a lot of antibodies, when injected under the skin, have trouble making it from the injection site to your bloodstream. This can be solved by administering via IV, but that has many downsides when it comes to patient convenience.

    The reason vaccines are the first successful application of this technology is because they only require very small doses to be effective. Compare the amount of protein that is in a flu shot (60 micrograms in Fluzone at most) to a typical mAb (~150 mg up to 1 g at most), you can see how much less the vaccine requires. I fully expect that as the upstream and downstream processes for LNP manufacture improve and are able to scale, that we will see mRNA take over what is currently the realm of biologics.











  • This pretty much lines up with my take as well. Educating borrowers via the first three bills on true costs, expected earnings, and repayment options is fine, but is mostly done already. I don’t see how mandating a form that needs to be signed saying that you understand the debt you are taking on is going to change that.

    The fourth bill is pretty blatantly ideologically motivated. If they truly think that these programs are worth less, then a better solution might be something like tying the cost of tuition for different majors to the expected earnings potential rather than eliminating aid eligibility.

    The fifth bill would have a dramatic impact on graduate students. I am lucky enough that I did my PhD back when a graduate student stipend could (just barely) cover living expenses. However, graduate student pay has not kept up with cost of living, and grad students often take out the PLUS loans to help bridge the gap. Eliminating these would essentially price out a lot of grad students in HCOL areas that don’t have family wealth to draw from. Alternatively (and preferentially), it could motivate schools to actually pay a living wage to grad students. However, the most likely outcome is that schools would just bring in more wealthy international students to fill the enrollment gap.