Aucbvax.1505 fa.human-nets utzoo!duke!decvax!ucbvax!DERWAY@MIT-ML Wed Jun 3 00:42:46 1981 HUMAN-NETS Digest V3 #111 HUMAN-NETS AM Digest Wednesday, 3 Jun 1981 Volume 3 : Issue 111 Today's Topics: Administrivia - Content of Human-Nets, Left Handed Sugar - Isomer Chemistry & Heavy Water Biology & Reversing Matter ---------------------------------------------------------------------- Date: 06/03/81 00:49:19 From: The Moderator Subject: Submissions to Human-Nets Increasingly, Human-Nets has become a broader and broader discussion, until now there are clearly people that view the list as a place to discuss whatever happens to be on their mind. To a certain extent, this may be due to the age of the list. Perhaps we have discussed so much of the area directly related to our supposed subject, that it is difficult to find new ideas in those areas. I have been receiving complaints recently, about the randomness of the topics discussed in Human-Nets. Consider, (especially just before you send that message!), that over 3,000 people will be reading it. Does it really have anything to say? Roger Duffey established the policy of never rejecting a message that wasn't in some way out and out objectionable. Since then, the list has grown, and the incidence of submitted messages, which say nothing of interest, EVEN ON THE TOPIC THEY PURPORT TO DISCUSS, has grown sharply. The combination of the breadth of the discussion, and the high ratio of nonsense to informative, interesting messages, is causing a real problem in that they grossly slow down the exchanges, and annoy a good many people, particularly those with slow terminals. Please think a little longer before sending in an off-the-cuff comment, or a message that really doesn't make any point. I should never have allowed the left handed sugar discussion to take place. I first published the reprint of the news article because someone had sent it in, it wasn't objectionable, and I even thought there might be a fairly wide interest in it. Unfortunately, the latter was all too true. I really had not thought that a discussion was appropriate over the list. However, all of these people worked hard on the messages, so here they are. Please, keep further discussion among yourselves, as it really has no relevance to Human-Nets. Thankyou, Don ------------------------------ Date: 21 May 1981 04:36 edt From: JSLove at MIT-Multics (J. Spencer Love) Subject: Re: Jerry Leichter's message on sugars Your memory of chemistry is faulty. There are LOTS of ways to hang 6 water molecules worth of atoms on 6 carbons; these are called isomers. Glucose (also called dextrose), fructose (also called levulose) and mannose are just three; there are many others. Those three are all "right handed" sugars; none are mirror images of each other. My CRC gives fucose as a left-handed sugar; where it occurs I don't know. Then there are the 12-carbon sugars, of which sucrose, maltose, and lactose are examples. And 18-carbon sugars like raffinose. Sucrose is glucose + fructose - H2O, while maltose appears to be glucose + glucose - H2O. Unfortunately, this is an oversimplification: my CRC gives alpha and beta forms for glucose, with slightly different characteristics. Lactose is a 12-carbon sugar that can be found in milk and that some people lack the enzyme to digest. Actually, most people lose it when milk stops being a significant component of their diet, but lacking it is much more critical at age 3 weeks. I don't know if it is a component in milk allergies, but if it is, then it would be an example of a toxic sugar isomer. It would be nice to know whether any mirror image sugars (of nontoxic sugars) are toxic; I expect we will find out soon. As I remember it (my term to go out on a limb), we can only metabolize (that is, make ATP using) one sugar isomer: dextro-glucose (by various pathways), so to utilize another sugar we must have an enzyme to mung it into one or more glucose molecules. That is why fructose is said to be better for you; the conversion acts as a bottleneck and causes the glucose to be released into your system more gradually, which is less of a shock to the regulatory mechanisms. Of course, any isomer that we lack the enzyme to convert is just so much bulk (like adding cellulose to food). This difference is more subtle than simple "sugarness", so it isn't surprising that levulo-glucose can't be converted. At least it's safer than eating antimatter... How are calorie counts calculated for such foods? The energy is there but inaccessible. For some foods I have read that simple burning will suffice, measuring the heat produced, but this fails when much cellulose is present, and indigestible sugars will make it worse. Are there microorganisms that are cultured for this purpose that have similar digestive capabilities to homo sapiens? I have read of an amino acid combination that tastes sweet, although you can't heat it up much or it denatures. It seems the critical thing is some bond angles on the sugar, which any compound might duplicate. So it seems quite plausible that the mirror image of glucose would taste identical to glucose; same for sucrose. Would some PRACTICING biochemist like to set the record straight by typing in a list of six and twelve carbon sugars, the breakdown of the more complex ones,and their handednesses (if different from the right-handedness that has been repeatedly mentioned in this forum for glucose)? Toxicity and sweetness levels would be nice, too, but I guess that diagrams showing exactly how all the isomers differ would be too much to ask (tho you could include a reference, a CRC is pretty useless for this). Thanks... ------------------------------ Date: 28 May 1981 2005-EDT (Thursday) From: Mark.Sherman at CMU-10A Subject: Left vs. Right Handed Substances During the sugar discussions, I got the impression that some people were not convinced that different stereochemistries of a substance could have different effects in the body. According to the Wasacz in the latest copy of American Scientist, morphine comes in both left handed (levorotatory) and right handed (dextrorotatory) forms, but only left handed morphine is analgesic and addicting. -Mark ------------------------------ Date: 28 May 1981 (Thursday) 0754-EST From: RUBENSTEIN at HARV-10 Subject: Heavy Water and isomers Since deuterium is heavier than normal hydrogen, reactions involving it are slower when the hydrogen is involved in the rate limiting step. Certain enzymatic reactions are slowed considerably when run in heavy water; the example that comes to mind is the family of sugar isomerases which are slowed by something like 45%. The net effect of all this, if I remember correctly, is a horrible, retching death after 12 to 16 hours, with LD50 around 150 or 200 ml for adults. I don't have a Merck Index handy, but that's what I remember. As to mirrors, would your mirror change a positive to a negative charge? No? Then don't worry about that anti-matter explosion. The difference between matter and anti-matter is more than handedness. The spin would reverse, but most stable systems consist of pairs of electrons with opposite spin. Likewise for nuclear spin (unless you're in a magnetic field of the tens of kilogauss variety). Hope this clears up a few misunderstandings. Stew Btw, heavy water always struck me as a really neat murder weapon. 200 mls isn't that expensive (about $80). Who ever heard of doing a mass isotopic abundancy analysis during an autopsy? ------------------------------ Date: 28 May 1981 (Thursday) 1607-EST From: RUBENSTEIN at HARV-10 Subject: Heavy Water and isomers Upon checking my source, I have to admit that my memory of the lethal dose of heavy water was based on an oft-repeated myth. According to Merck Index, Heavy water is considered non-toxic, though it stunts the growth of mammals on prolonged exposure, presumably due to the slowdown of enzymatic reactions. Too bad, I still think it would have made a great murder weapon. Almost as good as the dagger made of ice. Stew ------------------------------ Date: 05/28/81 08:08:22 From: TK@MIT-AI Subject: Heavy Water Deuterium oxide (heavy water) is poisonous, and will kill you when consumed such that your total water intake is about 60% D2O. The bug is apparently the rather subtle change in the hydrogen bonding, which makes things like DNA work. ------------------------------ Date: 28 May 1981 06:11:15-PDT From: decvax!duke!unc!smb at Berkeley via Subject: sterioisomers About Will Martin's query on deuterium: I'm a little skeptical that it would have much effect, but it might. For one thing, biologists often tag molecules with tritium, and I've never heard that this interferes with their function. On the other hand, the ratio of O-16 to O-18 is used as a clue to climate in the past, so there is SOME effect there. Incidentally, not all science fiction writers have neglected the anti-matter problem. The reversing machine in Zelazny's "Doorways in the Sand" was described second n-axial inversion unit. It seems that the first one lacked a "particle exceptor program".... ------------------------------ Date: 28 May 1981 11:26:42-EDT From: cjh at CCA-UNIX (Chip Hitchcock) Subject: chemistry and reversal As an ex-chemist, my first remark about the alleged problems of deuterated water (i.e., \\not// tritiated, which would be radioactive) is that it's almost certainly nonsense. The problem is that the old definition of isotopes as those forms of an element that were not separable by chemical means is fading as the boundaries between physics and chemistry are fading; the latest CHEMICAL & ENGINEERING NEWS reports from the last national ACS meeting that someone has found a reaction that behaves differently if several of the hydrogens are replaced with tritium. Since this is still a relatively subtle difference, I strongly doubt that it supports the idea that deuterated water would not serve the same physiological functions as ordinary water. Biochemical reactions are primarily a matter of sizes, shapes, and relative concentrations, and the size, shape, and molecules/space of heavy water are all \\very// close to those of ordinary water. With regard to the proposed sugars, the first question is what process is used; the FDA has standards for decaffeinated coffee, for instance, because decaf is sometimes made by dissolving out the caffeine from the beans with methylene chloride, which is \\not// something you want to consume. Any process that would invert a normal sugar would be fairly drastic chemically, so the same standards against residuals would apply. Of equal concern is the effect of another indigestible substance on the body; the low-bulk American standard diet has disadvantages but a high-bulk diet is not without problems either. (This is more of a concern for the plan to bind the sugars to indigestible polymers.) Also, when I was doing some research several years ago in producing a preponderance of one optical isomer of a given amino acid, I remember being told that some of the mirror images of necessary amino acids were known to be toxic; without any preexisting information the FDA is right to be concerned about this. If the manufacturing proposals were simply to sort out an isomer from a mixture of sugars known to be tolerable, there wouldn't be a problem; but I don't think that is the case. ------------------------------ Date: 28 May 1981 at 0842-PDT Subject: Reversal Symmetry From: zaumen.tscb at Sri-Unix There is a technical error in Bruce Lucas's comment about mirror images: the mirror-image of matter in not anti-matter because anti-matter differs in other quantum numbers besides parity (such as lepton number, baryon number, etc). The confusion is over symmetries: Certain physical laws are invarient under parity (mirror-imaging), others are invarient under charge-reversal, and others under time-reversal. It turns out that all of these seem to hold for the strong interactions (nuclear forces) and all of these fail (individually) for the weak interactions. Quantum field theory predicts (assuming only causality) that all physical laws are invarient under the combination of all three symmetries (CPT invarience). So far, CPT is the only one that works in every known case, and if that fails, either relatavistic quantum mechanics or causality is in serious trouble. ------------------------------ Date: 05/28/81 17:38:40 From: KWH@MIT-AI Subject: Reversing atoms? :flame Huh? The mirror image of matter is antimatter? You're confusing topological and physical terminology- The mirror image and fourth dimensional twisting, and the handedness issue is all a part of topology- Look at your right hand- and your left hand- and try to transform them into each other. The difference between them is topological, and you can't do it, by the same token that by twisting a right-hand glove around, you can't fit it on your left hand. You can flip a two-dimensional object from right to left handed, by just flipping it over (Physically) But you can only flip a three dimensional object over in a fourth spacial dimension- (You can also flip a two dimensional object over, however, by running it over a mobius strip, and if you jam yourself through a Klein bottle, you will flip around) But you still wouldn't be made of antimatter- Matter is RADIALLY symmetric, with electrons around a positive nucleus, antimatter is similar, but with postive particles around a negative nucleus, but in either case, flipping gets you nowhere- How can you have a "right-handed" ball? Flipping it does nothing. However, there is a neat theory by Feynaman that proposes antimatter is regular matter moving backwards in time... Maybe that's why we don't have visitors from the future, they start up the time machine and blow the earth and themselves to pieces..... :unflame Ken Haase ------------------------------ Date: 29 May 1981 (Friday) 0324-EDT From: SHRAGE at WHARTON-10 (Jeffrey Shrager) Subject: ragus desrever I suspect that this entire conversation belongs in SFL but... Firstly, who says that sending someone thru a reversal machine will reverse down to the subnuclear level? Did you build the machine? Do you have any idea how it works? Maybe is has a LOOP UNTIL LEVEL=ATOMIC in it someplace. Also, what would the result be if we went and reversed even deeper than the anti-matter level? Can you reverse quarks? Can you even reverse anything lower than a molecule in the isomeric sense (probably not). At lower levels you're dealing with spins and resultant charges rather than structure but I don't think that anyone really knows what's what down there so maybe the structure of a proton dictates the charge. As to the FDA's legal rights and their interpretation of the law... given half a chance, they'd outlaw distilled water! ------------------------------ End of HUMAN-NETS Digest ************************ ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.