5 ms·
I assume volume is the problem. Can anyone explain what the speeds are required to freeze any particular organ safely?
by bojo 3y ago
I assume volume is the problem. Can anyone explain what the speeds are required to freeze any particular organ safely?
- elromulous 3y agoI imagine freezing is the less problematic side. You can probably dump it in liquid nitrogen (exaggeration, but you get my point). But you can't heat it fast (enough) because the extreme heat would burn/vaporize the exterior while the inside is still cold.
- littlestymaar 3y agoI'm not sure about what's the problem with slow thawing though: AFAIK most tissues are pretty stable at fridge temperature for a few hours (from 4hours for a heart, up to 36hours for a kidney), but freezing is another matter: the slower you freeze things, the bigger the ice crystal grow, and IIRC you need to freeze things very quickly if you don't want damages from the ice crystal (you want to “vitrify” the water, instead of crystalizing it) and I don't think even liquide nitrogen is enough to freeze big organs quickly enough.
- AstralStorm 3y agoThere are some tricks with cryoprotectants and rarely used cryopreserving protein, but triggering that and not damaging cells is an active field of research.
- Vecr 3y agoI remember there being research where they successfully froze and then revived hamsters in the microwave (a scientific one to prevent uneven heating though), but it had no hope of working in people or even cats and dogs.
- greazy 3y agoThis is partly true https://www.thestar.com.my/news/true-or-not/2021/12/30/quickcheck-were-microwave-ovens-originally-developed-to-reanimate-frozen-hamsters https://www.thestar.com.my/news/true-or-not/2021/12/30/quick... Nowadays we have much better tech for rewarming frozen animals.
- ginko 3y agoAfaik the problem isn't the rewarming, but the quick and even freezing.
- elromulous 3y agoA scientific hamster? :P
- tschwimmer 3y agoah yes, the well known "hot pocket" problem - one of the most challenging in cryogenics
- bluSCALE4 3y agoThere has to be a trick to cooling something fast enough then freezing it. People falling into freezing water, dying, then being revived ours later comes to mind. I do suppose actually freezing is very different but who knows, maybe there could be a connection?
- AstralStorm 3y agoThe body has time to prepare for the cold by making a lot of cryoprotectants in the cells. That of course only works in quite particular conditions and in a liivng host, and the induction would be quite painful. The remaining damage of defrost is fixed later on.
- lm28469 3y ago> People falling into freezing water, dying, then being revived ours later comes to mind. Except this doesn't exist, these people don't actually freeze, as in they never go bellow 0, most of them stay well above 0 actually. They're very different phenomenons For example: https://jmedicalcasereports.biomedcentral.com/articles/10.1186/s13256-019-2282-6 https://jmedicalcasereports.biomedcentral.com/articles/10.11... > A 52-year-old Italian mountaineer, was trapped in a crevasse and rescued approximately 7 hours later by a professional rescue team.... His core temperature was 26.0 °C or: https://en.wikipedia.org/wiki/Anna_Bågenholm https://en.wikipedia.org/wiki/Anna_Bågenholm > her body temperature decreased to 13.7 °C (56.7 °F), one of the lowest survived body temperatures ever recorded in a human with accidental hypothermia.
- bluSCALE4 3y ago>> People falling into freezing water, dying, then being revived ours later comes to mind. > Except this doesn't exist, these people don't actually freeze, as in they never go bellow 0, most of them stay well above 0 actually. They're very different phenomenons Yep, I stated that as well.
- bryan0 3y ago> Afterward, they cool it quickly — 24 degrees Celsius per minute — to bypass the formation of cell-shredding ice crystals and directly enter a glass-like state.