+ Reply to Thread
Page 3 of 3 FirstFirst 1 2 3
Results 21 to 26 of 26

Thread: Pure O2 CCR Dive Time and Depth limits.

  1. #21
    Resident bibliophile Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs is a name known to all Gene_Hobbs's Avatar
    Join Date
    Sep 2006
    Location
    Durham, NC, USA
    Posts
    179
    Megalodon

    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by bendomatic  View Original Post
    And free radicals are a normal required part of cell metabolism and cell signalling. So you just can't go about eliminating them completely, otherwise everything will go A over T. Interestingly in the extracellular environment in humans, the most important anti-oxidant is uric acid.
    Yeah, I should have been more clear, their work have been on oxygen exposure extension, NO, sepsis, and the like... PubMed can tell more about their work than I can. ;)

    As for Oxygen and SOD, we scanned these for UHMS a while back:

    Gottlieb SF, Longmuir IS, Totter JR (eds). Oxygen: An In-Depth Study of its Pathophysiology (Volume 1 and 2). 28th Undersea and Hyperbaric Medical Society Workshop. UHMS Publication Number WF145.U55.1983p. Bethesda: Undersea and Hyperbaric Medical Society; 1983; 665 pages.

    Shilling CW (ed). Superoxide Dismutase (SOD). A Bibliography with Informative Abstracts. UHMS Publication Number 48(SOD)4-1-81. Bethesda: Undersea and Hyperbaric Medical Society; 1981; 262 pages.

    jcolley- PLEASE write your friend. One thing I have learned in this project has been that nobody knows where everything is and he may have some interesting insight.

  2. #22
    RBW Member RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan's Avatar
    Join Date
    Feb 2005
    Location
    Pacific NorthWest USA
    Posts
    1,238
    Meg

    CCR Dolphin

    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by jcolley  View Original Post
    As long as the manals are followed, safety is not an issue.

    Jim
    taken out of context, this is pretty funny...

    and they say that military intelligence is an oxymoron... :D

    great thread guys, thanks for the info and references

    always learning...

  3. #23
    Normal people worry me jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap's Avatar
    Join Date
    Jun 2005
    Location
    Stockholm Sweden
    Posts
    634

    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by Dave ******  View Original Post
    The following was excellently written:

    "If the amounts of free radicals get too high, the normal mechanisms for "soaking up" these compounds can be overwhelmed. The FRs then start to react chemically with a whole host of areas within the neuron (brain cell) which would usually be protected from them. This in turn interferes with the routine “ housekeeping” processes in the neuron that keep it functioning normally"



    So..... something I have been positing for years, to empty stares (and no actual answers) from some of the leading hyperbaric physiologists in the world:

    QUESTION:

    "Why has the hyperbaric medical community not performed research on a chemical method of dealing with this issue? As a working hypothesis, let me posit that if the quacks were able to make a compound to deal with the FR's at the chemical level, and we were able to inhibit the possibility of 02 tox by taking a little pill, then as a result we would all be able to enjoy no deco / no narcosis diving on pure 02 at just about any depth".

    The last time I asked Bill Hamilton that question he looked thoughfully into the distance, took a sip of his martini, and started thinking and never answered.

    Just to pull the tail of the thinkers here.


    Dave

    How about the fact that we are not sure of the exact link to this "free radical"-effect. Sure, we know "free radicals" are formed from O2 all the time.

    I say "free radicals", since I suspect that many do not know much about any possible mechanisms. Yet they say things like, well its those "free radicals".

    Infact O2 itself is a biradical (it has two unpaired electrons). So you cannot be wrong if you say radicals are involved when radicals do something.

    I have not seen any good proof of what actually causes it to happen and what happens on a chemical level when a diver is toxing.

    Saying that it probably has something to do with oxidative stress is likely a cautious statement. But to demand a pill to fix it...is a huge task. I think.

    Infact our bodies are already rather defective when in comes to converting O2 to energy. Something like 2% of the electrons in the electron transport chain that keep us alive stray away leading to the formation of "radicals". This coupled with the fact that we breath O2 has forced our bodies to constantly use its antioxidative functions to keep us alive.

    Some even argue that its the "free radicals" that make us age. Like the now rather old: Free radical theory of aging

    So in a way demanding a pill to prevent toxing could be a bit like demanding a pill to stop aging...

    I feel this general "free radical" stuff is something easy to blame and since most people get really impressed by any sort of chemistry they accept it.

  4. #24
    Banned MB is an unknown quantity at this point MB's Avatar
    Join Date
    Jun 2006
    Posts
    0

    Re: Pure O2 CCR Dive Time and Depth limits.

    [quote=jaap;80724]So in a way demanding a pill to prevent toxing could be a bit like demanding a pill to stop aging...
    quote]


    I said it was just to pull the tail.... consider it pulled.


    Dave

  5. #25
    Flaccid Member abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie is a splendid one to behold abowie's Avatar
    Join Date
    May 2005
    Location
    Land of Oz
    Posts
    801
    Dammit I bought another KISS

    CK, SK, Satori, ManBagOD

    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by jaap  View Original Post
    I feel this general "free radical" stuff is something easy to blame and since most people get really impressed by any sort of chemistry they accept it.
    If you read a bit of an undergraduate biochemistry textbook I suspect you might become more convinced.

    Sure what I have written is a gross oversimplification of the problem but it was pitched at the layman and my knowledge of biochem is fading now that I am 20 years out of med school :D.

    A lot of the stuff you read about FRs in the popular press is plain bullshit aimed at selling unnecessary vitamins to you I agree, but they're a real enough problem at a subcellular level.
    Last edited by abowie; 29th November 2006 at 23:36. Reason: spelink

  6. #26
    Normal people worry me jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap's Avatar
    Join Date
    Jun 2005
    Location
    Stockholm Sweden
    Posts
    634

    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by abowie  View Original Post
    If you read a bit of an undergraduate biochemistry textbook I suspect you might become more convinced.

    Sure what I have written is a gross oversimplification of the problem but it was pitched at the layman and my knowledge of biochem is fading now that I am 20 years out of med school :D.

    A lot of the stuff you read about FRs in the popular press is plain bullshit aimed at selling unnecessary vitamins to you I agree, but they're a real enough problem at a subcellular level.
    Hey I'm not saying radicals are a load of BS.

    Of course they are for real, what I'm saying is that I belive that our understanding of the mechanisms of acute O2-tox (dry & wet) are not complete enough to give the full answer. But that it seems like its always handy to start off on the free radical track even tough the full understanding is not there.

    I better don some fire resistant gear

    Or maybe I missed some breakthrough publications? I'm in no way a specialist in this field. I only did my M.Sc diploma work on free radical degradation of polymers. So I'm just a happy amateur with a side interest in diving related chemistry.

    ....read a bit of an undergraduate biochemistry

    Yes, my copy of

    Free Radicals in Biology and Medicine Barry Halliwell and John Gutteridge

    Was already falling to pieces from my overreading of it 10 years ago, but you are right. More reading is probably good.

    As a sidenote my latest project is nudging the real radical experts in my department to get into more diving related stuff. Like the mechanism of NO suppression of bubbleformation.
    Last edited by jaap; 30th November 2006 at 00:48. Reason: spelling as usual...

+ Reply to Thread
Page 3 of 3 FirstFirst 1 2 3

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts