Wikipedia:Reference desk/Archives/Science/2023 August 17

= August 17 =

Patterns for making "court" shoes with a block heel..
Does anyone here know of any 'free' patterns for these?

Alternatively does anyone know of any books on drafting patterns for footwear that are compatible with Wikimedia licensing policy? ShakespeareFan00 (talk) 10:05, 17 August 2023 (UTC)
 * This 1885 book has some shoe patterns. Abductive  (reasoning) 10:48, 17 August 2023 (UTC)

Transplantation into brain-dead bodies
There was a recent report on pig kidney transplant into brain-dead man in the US and surgeons claimed success stating that the transplant has continued to function for 32 days. Particularly, it was claimed that the kidney was not rejected in the minutes after it was transplanted. How on earth it's possible for a kidney to work in a brain-dead man? Seemingly, the question of organ rejection or acceptance isn't relevant for a dead man, to begin with. 212.180.235.46 (talk) 11:00, 17 August 2023 (UTC)
 * The brain was dead while the immune system not. Ruslik_ Zero 11:21, 17 August 2023 (UTC)
 * I do agree that it seems the OP seems to be confused about the overall meaning of brain death, but it is worth mentioning, because of the very broad application of the term "brain death" (in the lay context and clinical environments both) that there are actually some immune functions that get some degree of mediation from the central nervous system. Of these (still somewhat nebulously described in some cases) mechanisms that I know of, I can't think of one that necessarily would create major concerns for a case study of this nature, but depending on the exact nature, but depending on the precise neuroanatomical nature of the brain damage and dysfunction, it's not entirely impossible--especially since inflammation response is a part of the pathways that may (again, very murky area) borrow some regulatory function from the parasympathetic nervous system and this is also a function of the immune response of concern for rejection.  Of course, presumably those running this particular study either have dismissed the likelihood of impact in the case of such mechanisms and/or the particular damage in this case does not involve the relevant localized areas. SnowRise let's rap 14:18, 17 August 2023 (UTC)
 * See also Vegetative state, a person may have no higher-order brain functions, but their bodies may continue to maintain living otherwise, often for a very long time. -- Jayron 32 11:59, 17 August 2023 (UTC)
 * Ok. This says the brain-dead man is "being kept on a ventilator and other life supporting measures until the study concludes". To keep the kidney working I assume this includes some circulatory/cardiac life support and injection of water/fluids? 212.180.235.46 (talk) 17:31, 17 August 2023 (UTC)
 * In a sense there is direct circulatory support, but not of a mechanical variety, if that is what you are asking. First, it's important to understand that "brain death" has come to serve as a catchall for a span of different degrees of neuromorbidity.  It may mean the loss of all higher cognitive functioning and any chance of a recovery of consciousness (but a still functioning brainstem), or it may involve the death of the brainstem as well (which is very typically the last portion of the brain to lose functioning if there is a cascade of damage to the brain).  Increasingly there is a trend to push the term back to its original meaning (all lose of significant function, including the brainstem), but you still see a lot of variability out there--especially in lay literature.


 * In any event, if the brainstem is still functioning, autonomic functions may be maintained for some time. Once the brainstem no longer functions, however, the clock is ticking.  This is where we get to your most recent specific inquiry: there is no need (or indeed, medically practical methodology) to force the circulation of the blood through the body once the heart has stopped beating.  However, the heart contains its own pacemaker in the form of the sinoatrial node, and a broader system for transmitting electrical impulses through the heart to induce regular and rhythmic contraction (see cardiac conduction system).  These systems are innervated and connected to the brain stem under normal circumstances (as are numerous other organs and metabolic pathways), so the system is by no means in a healthy spot once brain death (in the sense of brainstem ceasing to significantly function) has occurred, but so long as the heart continues to get an adequate supply of oxygen, it can continue maintaining a normal sinus rhythm for a while.  This would typically require rapid intervention and intubation before the brainstem had lost all function, however.


 * In cases where the maintainance of the body after the point of true (brainstem included) brain death (which doctors will typically not want to do at this juncture, as there is zero chance of recovery, but may in the case of organ harvesting or when forced to by legal disputes), vasopressors and anticoagulants can be used to try to support cardiac function, but inevitably once the brain is no longer providing important mediatory functions for various systems, cardiac arrhythmias, widespread inflammation, and coagulation sets in.  And that's just focusing on the circulatory system: other vital functions will be compromised and will accelerate the decline as well.  Despite this, in some extreme cases, heart and lung function has been maintained for up to months at a time.  But it is just a matter of time, and usually multi-system collapse will begin in a matter of hours or days, and all remaining respiratory, circulatory, and metabolic activity will cease. S<b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 20:10, 17 August 2023 (UTC)
 * That's a revelation for me, thanks. 212.180.235.46 (talk) 09:29, 18 August 2023 (UTC)
 * You're most welcome! <b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 09:33, 18 August 2023 (UTC)