Newsgroups: alt.drugs From: [p c k] at [acsu.buffalo.edu] (P. C. Kilinskas) Subject: N20 (reasonably safe) was: Nitrous oxide (DOES kill nerve cells!) Date: Tue, 11 Jan 1994 17:46:40 GMT [c h ris] at [hacktic.nl] (chris) writes: >damage! It irreveribly inactivates the vitamin B12 containing enzyme >methionine synthase, which leads to neurologic symptoms. Several reports "Irreversible" is a misleading term, since it refers to the change to a particular enzyme, and not the human being. This was clipped from a.d awhile back, and includes a reference: ----- Basically, B12 is a bound coenzyme of methionine synthase and has a tetrapyrrole rings with a monovalent cobalt at the center. The cobalt functions as a methyl carrier in a transmethylation reaction. Nitrous oxide converts the cobalt from the monovalent form to the bivalent form. As a result, methionine synthase activity is inhibited. Recovery is believed to require absorption of new unoxidized B12 (and synthesis of new apoenzyme). Humans seem to be far more resistant to complications from this than rodents. I don't have the energy to go through the various published studies at this point, so I will quote from Nunn's "Clinical Aspects of the Interaction Between Nitrous Oxide and Vitamin B12" (1987), _Br. J. Anaesth._ 59: 3-13. It seems likely that in man, in contrast to the rat, exposure of less than 30 minutes will not cause any measurable change in methionine synthase activity. In combination with a wealth of clinical experience, this suggests that there is no special hazard for short exposures to nitrous oxide. There is a variable response to exposures lasting between 30 minutes and 2 h. However, it now seems likely that exposures of more than 2 h are likely to cause intereference with hepatic methionine synthase activity. The paucity of human data makes it more difficult to say how long an exposure is required to cause significant intereference with DNA synthesis. It is likely that there will be considerable individual variation and results obtained in healthy patients cannot be extrapolated to the patient who is seriously ill. Nevertheless, it seems likely that, once methionine synthase activity is inhibited, it will remain so for days. With respect to repeated exposures to nitrous, be aware that this effect can build up (Nunn gives "intervals of less than 3 days" as a cut-off). So, go easy on the "hippie crack," people! Mandatory nitrous horror story: Layzer (in (1978) "Myeloneuropathy after prolonged exposure to nitrous oxide," _Lancet_ 2:1227) reports a case of 15 people who had been inhaling nitrous oxide for long periods of time and developed a condition resembling subacture combined degneration of the cord, whatever that means. ------------ N2O has not been shown to be dangerous in small (i.e. "whippit") amounts. Phil ____________________________________________________________________________ [p c k] at [acsu.buffalo.edu] / "Our days are like grass..." - Psalms 103:51 Your eyes are weary from staring at the CRT. You feel sleepy. Notice how restful it is to watch the cursor blink. Close your eyes. The opinions stated above are yours. You cannot imagine why you ever felt otherwise. From: [c h ris] at [hacktic.nl] (chris) Newsgroups: alt.drugs Subject: Nitrous Oxide Dangers Date: 12 Jan 1994 21:52:13 +0100 Summary: 2 case reports of neurological damage due to nitrous oxide NITROUS DOES IT KILL BRAIN CELLS? In an earlier post I mentioned some scientific reports on the possible dangers of prolonged exposure to nitrous oxide. This elicited some reactions that focus around the definition of "prolonged exposure". How much nitrous taken in how much time will rot your nerves? To get an idea i will transcribe two case reports from a more recent nitrous horror story. At the same time it will give you an idea what "neuropathy" and "myeloneuropathy" looks like and what signs to watch out for when you are a nitrous regular. From: Stacey et.al (1992) " Methionine in the treatment of nitrous oxide induced neuropathy and myeloneuropathy" Journal of Neurology 239:401-403. Case 1 (quote) This 36-year old electrical engineer came to the emergency room complaining that he was unable to walk. Symptoms had begun 4 days earlier with "pins and neeedles" in both feet that gradually worsened and ascended to involve the knees and the fingertips. With worsening of the paresthesias (-no sense of touch or pain-) he noted difficulty in maintaining proper control of the movements of his arms and hands and trouble in walking. He also reported the sensation of electric shocks through his back and legs upon flexion of the neck. He denied bladder or bowel impairment but he had been unable to have an erection for the past week. His past medical history was unremarka- ble except for occasional abuse of alcohol in the past. However he denied any drinking of alcohol for the past 8 months. For recreational purposes he had inhaled two to three boxes of nitrous oxide, each box containing 24 cartridges, practically every day for the past six months. When first seen his general physical examination was completely unremarka- ble. The neurological examination showed hyperesthesia and hyperalgesia in the lower extremities up to the knees. He had severe bilateral sensory dystaxia and could only stand with support. (-More Neurological and Blood statistic Stuff Deleted- ed.). Intramuscular B12 injections were started and during the following days his hematological status inproved, (-apart from neurological symptoms, the functional B12 deficiency caused by N2O also produces megaloblastic anemia,- ed.) although his neurological condition continued to deteriora- te. The paresthesias ascended to the nipples and he developed fecal and urinary incontinence. (- stuff deleted-) Four weeks later he began to improve and four months after the onset of the symptoms, and his last use of nitrous oxide he could walk with some hesitation and had completely regained bowel and bladder control and sexual function (-stuff deleted-). Case 2 This 32 year old woman was admitted tho the neurology service for inability to walk and paresthesias in her limbs and trunk. Her symptoms began 3 weeks prior to admission with a "tingling" sensation in the soles of her feet, trunk and hands. Her gait bexcame progressively less steady and the day prior to admission she had an episode of urinary incontinence. Her past medical history was significant for bulimia and occasional intranasal use of cocaine. for the previous 3 months she had inhaled nitrous oxide for recreational purposes, up to 200 cartriges a day, three to four times a week. (-stuff deleted, similar neurological signs as above, some antisocial behavior). (end quote) What this shows is that these people really did a lot of nitrous, say 300- 400 cartridges a week, for a few months in a row to develop these really nasty symptoms. But it also shows that people who do such things do exist ( can you believe it?) For the really health conscious among you (a contradiction in terms?) if you "must" do nitrous for a longer period be sure to take high doses of folic acid (is also depleted from your body as a result of functional B12 deficiency ) and vitamin B12. (No injury NOT guaranteed, but it might help) Also, but less well known, the state of B12 deficiency caused by regular use of nitrous oxide produces hyperhomocysteinemia, an accumulation in the blood of the amino acid homocysteine. Hyperhomocysteinemia is a risk factor for vascular disease of all sorts. Furthermore, hyperhomocysteinemia, B12 deficiency and folic acid deficiency early in pregnancy all increase the risk of getting a child with a neural tube defect (spina bifida and anencephaly, childeren with no brains or open spinal cord). If you are a woman, planning to get pregnant or just "at risk of getting pregnant", nitrous is a bad idea. If youre interested in this literature contact me. More literature on neurological aspects of nitrous use: Pulsson (1979) "Recreational" misuse of nitrous oxide, J. Am Dent. Soc. 98:410-411 Sahenk et al.(1978) "Polyneuropathy from inhalation of N2O cartridges through a whipped cream dispenser" Neurology 28:485-487. Chris ( [c h ris] at [hacktic.nl] )