Wikipedia:Reference desk/Archives/Science/2014 August 8

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

August 8

Bone marrow biopsies

Is the procedure highly painful? I would guess so, and story (below) makes me wonder more, but the "After the procedure" section of bone marrow examination mentions soreness and "worsening pain", but it doesn't address routine pain. Story: I have a friend with leukemia; he had a bone marrow biopsy recently, soon after he was told that chemotherapy had destroyed his cancer. If I understood rightly, they did this biopsy to see what was hanging around in the marrow still, and his extreme reluctance to undergo the procedure (basically a mindset of "I'm doing it because it's good for me, but I really really really don't want to") makes me wondering if there's a major pain issue (or other side effect) that patients frequently experience. I kept forgetting to ask my friend whether it were deeply painful, or otherwise I wouldn't have to come here. Nyttend (talk) 04:58, 8 August 2014 (UTC)

According to Roswell Park, yes, it can hurt. I am of course offering this answer purely to assuage your "'satiable curtiosity" and not in any sense at all as any kind of advice. DuncanHill (talk) 05:25, 8 August 2014 (UTC)

This depends on the skill of the anesthesiologist and dumb luck about whether you can remember the pain. Because if a tree falls in the forest, it makes a sound, but if nobody hears it, then it might as well not have. 104.128.96.117 (talk) 09:36, 8 August 2014 (UTC)

Thank you. This actually wasn't to assuage my curiosity; I'm about to improve the article somewhat. Duncan, it would help if you'd check my addition ("Site of procedure" section) to ensure that it follows the source. It shares some little bits of wording with the source, e.g. "cannot be anesthetized", but only at points when I couldn't think of an alternate wording. Nyttend (talk) 11:17, 8 August 2014 (UTC)

I will do so shortly, Nyttend. My comment about "for information only" was an attempt to fend off any misguided attempts to remove a perfectly reasonable question. DuncanHill (talk) 16:31, 8 August 2014 (UTC)

And your edits look good to me :) DuncanHill (talk) 16:41, 8 August 2014 (UTC)

Transport careers

Is a career in transport management and operations similar to event management? — Preceding unsigned comment added by Clover345 (talk • contribs) 15:48, 8 August 2014 (UTC)

This question sounds like the "Operations Sector" question from July 26. Nimur (talk) 15:57, 8 August 2014 (UTC)

The following is my un-referenced personal experience and opinion, for whatever you think that's worth. My grandfather was a transport manager and I have worked in companies which use transport to support their main activities (and still do). I have also been involved in amateur event management over a couple of decades (Fan-run Science Fiction Conventions and CAMRA Beer Festivals, if it matters).

I would say the two types of activity are very different, beyond the very basics of needing an organized and 'businesslike' approach and the flexibility to deal with the unexpected. Similarly, careers in them seem to me likely to differ markedly. However, professionals in either field would be better placed to advise on specifics. If none show up here to answer (as seems likely) you might try researching some leading companies in either field (local to yourself) and contacting their recruitment/personnel/human resources/whatever offices directly. All companies have to recruit new staff (on account of those pesky workers keep moving, retiring or dying) and should be eager to help genuine enquirers. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 19:15, 8 August 2014 (UTC)

Wood-burning cars and steam engines

This probably would have been equally at home at the humanities desk, but I'll add an additional component to make it more RDS-friendly...

In the book O Jerusalem!, reference is made to a "wood-burning Mercedes," without further elaboration (I don't have the book in front of me, but I distinctly remember being puzzled by the phrase and irritated that it was mentioned in such an offhand way). Does anyone know more about wood-burning models of Mercedes? Also, what exactly does "wood-burning" mean in this context? Surely these weren't steam cars, or were they? The idea of having a wood fireplace to heat a large car seems almost as absurd, though, so what's going on there?

And the more sciencey bit: what are the energy efficiency implications of using a steam engine in a car, or steam engines in general? Obviously using gasoline to heat water to boiling is going to be far less efficient than using the gasoline to drive the pistons directly, but what about with other fuel sources? There are still locomotives that use steam engines, but is it really more fuel efficient to use coal to drive a boiler than it is to liquefy that coal and use its energy directly? Evan ^{(talk|contribs)} 20:30, 8 August 2014 (UTC)

there's some information here that may be of use/interest. DuncanHill (talk) 20:34, 8 August 2014 (UTC)

We also have some info at Wood gas. --Mark viking (talk) 20:36, 8 August 2014 (UTC)

Notable is the Mercedes 35 hp, the very first car produced by Daimler to bear the "Mercedes" name was gasoline (petrol) fueled from the start. However, reading the Wood gas article, it says "Wood gasifiers can power either spark ignition engines, where 100% of the normal fuel can be replaced with little change to the carburation" The article Wood gas generator would also be a good read; it converts wood cellulose directly to wood gas to feed internal combustion engines; so literally you could feed wood into the car, and then run it. A wood-burning Mercedes then must be a Mercedes fitted to run with a wood gas generator. --Jayron32 20:49, 8 August 2014 (UTC)

See Steam car for the second part of the question. Most early 20th-century steam cars were oil-fired, although one major advantage of steam is that you can run it on anything flammable. Tevildo (talk) 21:29, 8 August 2014 (UTC)

True, but burning most things results in massive quantities of pollution. StuRat (talk) 23:20, 8 August 2014 (UTC)

During WWII, there were "coal-powered" VWs; see:[1] using the same wood-gas technology (e.g:Holzbrenner “Wood burning” Volkswagen). A 1945 Daimler "woodmobile" can be seen here:[2] — From this interesting article on the subject: [3]. Here is a Mercedes-Benz type 230 with the entire apparatus within the trunk:[4] 71.20.250.51 (talk) 22:20, 8 August 2014 (UTC) & 22:23, 8 August 2014 (UTC)

The German article also has several photos. Rgds ✦ _hugarheimur 03:52, 9 August 2014 (UTC)

Thanks for the replies, everybody. Fascinating stuff. Evan ^{(talk|contribs)} 22:26, 9 August 2014 (UTC)

Abdominal fat

Why is abdominal fat so hard to lose even with exercise and healthy eating? Is it genetics? — Preceding unsigned comment added by 94.14.151.66 (talk) 21:06, 8 August 2014 (UTC)

The tendency to put on weight there, versus other places, does seem to be genetic. Unfortunately, abdominal fat is also the most unhealthy. StuRat (talk) 23:21, 8 August 2014 (UTC)

That last sentence reads awfully like unsourced medical advice. HiLo48 (talk) 23:23, 8 August 2014 (UTC)

Doctors on TV frequently say that folks with belly fat, a.k.a. "apples", are at greater risk than those with backside fat, i.e. "pears". In fact, this doctor makes essentially the same statement: "Belly fat is the most dangerous type of fat." However, he also contradicts the OP's premise: "But I have good news: Belly fat is the easiest fat to lose!" ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:33, 8 August 2014 (UTC)

No 11 of my 'Rules of Life' says "Never believe anybody who is selling you something". Richard Avery (talk) 12:48, 9 August 2014 (UTC)

Probably a random TV show isn't the best source but there is a fair amount of research in to fat distribution and the correlation with different health outcomes. See e.g. Body shape#Fat distribution (we also have a Android fat distribution but it's totally unsourced). E.g. of research articles [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]. (A mix of stuff relating to the health outcomes and research on factors associated with different distributions since I was lazy to seperate them.) A quote from the first source which may be helpful for the confusion

There is little controversy that upper body/visceral obesity increases the risk for dyslipidemia (8), hypertension (9,10), type 2 diabetes (11,12), sleep apnea (13), etc. It is also recognized that increasing amounts of lower body fat are independently associated with a reduced risk of metabolic complications (14). Many (15,16,17), but not all (18), studies find that visceral fat mass is more strongly associated with an abnormal metabolic profile than upper body sc fat

Nil Einne (talk) 14:49, 9 August 2014 (UTC)

I wouldn't call The Doctors a "random TV show". It's a popular daily show with several doctors from various fields, exploring different medical issues each day. That doesn't necessarily make it "authoritative", but it's not "random" either. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:12, 9 August 2014 (UTC)

It depends a lot on what is meant by "exercise" and "healthy eating". If you still end up above a caloric deficit, or in surplus, you aren't going to be losing weight. That's not to say that genetics, and other such, don't play some role - just pointing out that healthy food alone won't cause you to lose weight if you are eating too much.Phoenixia1177 (talk) 03:31, 10 August 2014 (UTC)

Extraction of insulin from animal pancreas

The article on Insulin describes the work of various researcher who by the early 1920's had found means of extracting insulin from the pancreases of beef or pork and purifying it into a form which could be injected subcutaneously into humans to control diabetes. Collip was apparently quite important in devising a way to process the animal tissue into a useful extract, since researchers before his work with Banting, Best and McLeod had made extracts which lowered blood glucose, but which produced infection. My first question is, what would the process be, for making insulin from pork pancreas? This is for intellectual interest only, and certainly I am not looking for medical advice nor do I plan to actually do the process. I just wonder what a "recipe" might be for small scale production, in some hypothetical situation in a novel where synthetic insulin were not available, but animal carcasses were available. Something like "Take a fresh pork pancreas, (or isolate Islet cells from same), maintain it in some specified temperature range, macerate it in a blender with some solvent, filter, remove certain impurities by some process, concentrate the insulin by some process." Citing a book chapter or journal article describing the commercial process before the Humalog etc were invented would be a good response if it would be too long to describe all the processing, equipment and chemicals. The second question is, if insulin is a water soluble peptide, why is it impossible to preserve it as a powder to be reactivated by adding water, similar to the (different) chemical in the "Glucagon emergency kit" sometimes carried by diabetics, or as a long-term stable precursor chemical which could be processed into insulin by adding another chemical. The article Inhalable insulin says " Carl developed a method to preserve peptide hormones like insulin in the glassy state so that they can be pulverized into a powder and inhaled by diabetics as an alternative to self-injection." Such a "glassy state" or powder form might or might not be more stable over time or at more varied storage temperatures than the present liquid forms of insulin. Edison (talk) 21:29, 8 August 2014 (UTC)

Regarding the first question, I should note that this is not of historic interest only; if I recall correctly (based on conversations wih a diabetic acquaintance), porcine insulin was used alongside Humalog etc. until recently, so the details of the purification process are probably not hidden in some obscure pharmaceutical archive.

Also, this 1975 patent for a proposed improved purification method seems to describe the usual purification processes of the time. הסרפד (call me Hasirpad) 21:42, 8 August 2014 (UTC)

Porcine insulin is still used, according to the British National Formulary, as is, but rarely, bovine insulin. (From the July 2014 edition, section 6.1.1). DuncanHill (talk) 21:54, 8 August 2014 (UTC)

There's information here. DuncanHill (talk) 23:59, 8 August 2014 (UTC)

and this patent also has details. DuncanHill (talk) 00:01, 9 August 2014 (UTC)

and Eva Saxl is an article that is also relevant. DuncanHill (talk) 00:03, 9 August 2014 (UTC)

If you just go to PubMed and search for insulin, you can click on the last page (of 321635 results!) and look through a number of the old articles, which amazingly enough someone has actually put online. Here's an early purification [16] - only a partial purification at the time; remember that historically things like "insulin" refer to enzyme activities, not to single molecules per se. It appears that picric acid had a particularly important role; needless to say it is very "old school" biochemistry, though with a somewhat embarrassing degree of familiarity to the modern reader! Wnt (talk) 00:55, 9 August 2014 (UTC)

This looks promising. It does stress that you need fresh glands. DuncanHill (talk) 21:34, 9 August 2014 (UTC)

Having just now gotten one of the free Wikimedia licenses to access JSTOR, I sat long into the night reading up on the published early history of insulin, and have the basic info I was curious about. Collip would grind up a fresh animal pancreas, and use ethyl alcohol to extract the pancreatic enzymes. In a post apocalypse scenario, Everclear would be strong enough to achieve the extraction (I don't know if moonshiners could produce such nearly pure grain alcohol). A centrifuge was used to spin down solids. I wonder if a hand operated cream separator would suffice? It certainly would be more suited to volume production than a typical lab centrifuge which holds tiny test tubes. Insulin apparently can be separated from other soluble substances and proteins by increasing the strength of the alcohol. They would also filter out solids or precipitates initially by squeezing the macerated meat mixed with alcohol through cloth, and later the solution was filtered through paper. Banting at one point suggested that some of the filtering reduced the efficacy of the product, but its unclear if that held up. Various means were used to separate the fat. Refinements over the next year adjusted as well the acidity or alkalinity of the alcohol at various stages of the purification, and got a much higher yield per kg of pancreas, but an inefficient low-tech method would also work at a higher usage of animal pancreas. It did not require a lot of weight of pancreas to provide adequate insulin for a patient. When an alcohol solution of insulin is obtained, (say 95% alcohol/5% water) the alcohol can be removed by warming it to a modest temperature and putting a low vacuum over it. If done this, the alcohol can be recovered and reused. The millibars or fractions or millimeters of mercury in the vacuum are not generally stated, but it seem to have not been much of a vacuum, so a low tech suction pump might suffice, followed by a condensor to recover the alcohol. The fluctuating vacuum levels caused temperature variations and ruined the product when they initially tried to scale up to volume production. A lower-tech method (McLeod's) was to put the solution in a pan and blow warm air over it to evaporate the alcohol. The result of either process is a solution of insulin in water. A preservative was then added, and Banting said it would keep for a year at room temperature (modern vials suggest a month at room temperature). Strength was tested with rabbits: a "unit" of insulin would lower a 2 kg rabbit's blood sugar enough to cause convulsions in a certain percentage. That is the equivalent to today's differently-tested "unit." A post-apocalypse system of insulin production could plausibly be set up by your local labs which produce moonshine and crack, since insulin would sell for quite a high price. In the first couple of years of availability in the 1920's, it was not all that high tech, but the product was effective. Thanks to all. Edison (talk) 03:50, 12 August 2014 (UTC)