Glossary entry (derived from question below)
English term or phrase:
aging half-time
English answer:
AChE aging half-time (or, half the time it takes the refractoriness to reactivation to develop)
Added to glossary by
Mirra_
May 10, 2009 12:17
15 yrs ago
5 viewers *
English term
aging half-time
English
Medical
Biology (-tech,-chem,micro-)
chemical warfare / nerve agents (e.g. Sarin)
The aging half-time for Sarin is 5 hours.
context: aging of AChE-NA bond
AChE= enzyme acetylcholinesterase
NA = nerve agent
What is "aging half-time"? Thank you in advance.
context: aging of AChE-NA bond
AChE= enzyme acetylcholinesterase
NA = nerve agent
What is "aging half-time"? Thank you in advance.
Responses
References
| Aging of nerve agent |
Miriam300
|
Change log
Jun 22, 2009 00:48: Mirra_ Created KOG entry
Responses
3 hrs
Selected
AChE aging half-time (or, half the time it takes the refractoriness to reactivation to develop)
'aging' it is referred to the enzyme inactivation (due to the bond with the nerve agent), in this case it deals with 'AChE aging'
particularly
"'Aging,' i.e., refractoriness of reactivation due to rapid dealkylation of the Soman-inhibited enzyme"
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=ht...
These concentrations are well tolerated and keep a good portion of AChE in the active state, thereby retarding the AChE aging rate
http://lib.bioinfo.pl/meid:131101
However, the mechanism of mipafox-inhibited BChE or AChE aging needs to be investigated further; recent evidence has established that MIP-inhibited NEST
http://pubs.acs.org/doi/abs/10.1021/tx050342o
A test compound that inhibits acetylcholinesterase (AChE) aging has also been studied via computer modeling to determine the specific molecular events that
http://www.nal.usda.gov/awic/newsletters/v8n3/8n3army.htm
AChE aging follows an asymmetric bell curve with a maximum rate at pH 6, and three apparent pK a. ’s which implicate two carboxylic acids
http://www.weizmann.ac.il/sb/faculty_pages/Sussman/papers/19...
AChE aging is particularly rapid with dimethylphosphoryl compounds and may thwart effective reactivation by oximes, particularly in suicidal poisoning with
http://www.bioline.org.br/request?ph07019
and so on... :)
when the alkylic group is separated from the nerve agent, the oximes can no longer divide the nerve agent from the enzyme, so the AChE results permanently blocked, this is called 'AChE aging'
In other words, the time of aging is the time it takes one bound to break (n.a. - alkylic group). When this bound breaks another bound becomes permanent, i.e. the one between the n.a. and the enzyme (in your case the AChE).
Anyway 'aging' is referred specifically to the enzyme, particularly to the the bound that deactivates the enzyme, that is the bound with the nerve agent.
please see also
Pralidoxime Chloride (2-PAMCL) in the autoinjector (600-mg/2 cc) is the second drug for use in nerve agent poisoning cases. The 2-PAMCL removes nerve agent from the enzyme acetylcholinesterase as long as irreversible bonding (aging) has not occurred.
http://www.medtrng.com/special_operations_command_centr.htm
These concentrations are well tolerated and keep a good portion of AChE in the active state, thereby retarding the AChE aging rate.
AChE aging is particularly rapid with dimethyl phosphoryl compounds and may thwart the effective reactivation by oximes, particularly in suicidal poisoning with excessive doses.
http://pt.wkhealth.com/pt/re/tox/abstract.00139709-200322030...
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Note added at 3 hrs (2009-05-10 15:44:36 GMT)
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ah as a matter of fact you should keep the definition as it is, since
'AChE aging half-time' (or, just 'aging half-time')
is the exact, sufficient, and correct definiton for this process :)
--------------------------------------------------
Note added at 4 hrs (2009-05-10 16:33:48 GMT)
--------------------------------------------------
ah OK, sorry I didn't get it!
so you could use something like 'permanent inactivation' that, actually, exactly describes the meaning of 'aging' :)
http://www.google.it/search?hl=it&safe=off&num=30&q="AChE in...
--------------------------------------------------
Note added at 10 hrs (2009-05-10 22:29:02 GMT)
--------------------------------------------------
VERY interesting question!!! :D
and... after searching it (since the answerit is not at all an obious one) you are correct! but perhaps I would put it as "half the time the AChE-NA bond takes to become permanent"
see
"The ageing half-time (time for half of involved cholinesterase to age)"
http://ceaccp.oxfordjournals.org/cgi/content/full/6/6/230
(and since there is one bond for each AChE-NA complex it corresponds exactly to what you suggest)
also (considering it from the "bond point of view" ;)
"The bond between the enzyme and the nerve agent can age, a process by which the enzyme and agent become irreversibly bound. The half time for aging of sarin is 4 to 5 hours; this means that half of the bound sarin-enzyme complex can be reactivated 4-5 hours after sarin exposure by administration of the antidote. "
http://www.nj-ptc.org/training/materials/Liberty/NerveAgentA...
"Sarin's half time to aging (time at which aging has occurred in half the sarin-AChE complexes) "
http://www.gulflink.osd.mil/library/randrep/pb_paper/mr1018....
--------------------------------------------------
Note added at 12 hrs (2009-05-11 00:30:47 GMT)
--------------------------------------------------
anyway, just as an example, Italian texts keep the English term 'aging' - as (aging)' or "aging" - and accompany it with its explanation (most of the times it is "irreversible inhibition"). Sometimes 'aging' is also literally translated (i.e. the Italian term for 'getting old' is included ).
particularly
"'Aging,' i.e., refractoriness of reactivation due to rapid dealkylation of the Soman-inhibited enzyme"
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=ht...
These concentrations are well tolerated and keep a good portion of AChE in the active state, thereby retarding the AChE aging rate
http://lib.bioinfo.pl/meid:131101
However, the mechanism of mipafox-inhibited BChE or AChE aging needs to be investigated further; recent evidence has established that MIP-inhibited NEST
http://pubs.acs.org/doi/abs/10.1021/tx050342o
A test compound that inhibits acetylcholinesterase (AChE) aging has also been studied via computer modeling to determine the specific molecular events that
http://www.nal.usda.gov/awic/newsletters/v8n3/8n3army.htm
AChE aging follows an asymmetric bell curve with a maximum rate at pH 6, and three apparent pK a. ’s which implicate two carboxylic acids
http://www.weizmann.ac.il/sb/faculty_pages/Sussman/papers/19...
AChE aging is particularly rapid with dimethylphosphoryl compounds and may thwart effective reactivation by oximes, particularly in suicidal poisoning with
http://www.bioline.org.br/request?ph07019
and so on... :)
when the alkylic group is separated from the nerve agent, the oximes can no longer divide the nerve agent from the enzyme, so the AChE results permanently blocked, this is called 'AChE aging'
In other words, the time of aging is the time it takes one bound to break (n.a. - alkylic group). When this bound breaks another bound becomes permanent, i.e. the one between the n.a. and the enzyme (in your case the AChE).
Anyway 'aging' is referred specifically to the enzyme, particularly to the the bound that deactivates the enzyme, that is the bound with the nerve agent.
please see also
Pralidoxime Chloride (2-PAMCL) in the autoinjector (600-mg/2 cc) is the second drug for use in nerve agent poisoning cases. The 2-PAMCL removes nerve agent from the enzyme acetylcholinesterase as long as irreversible bonding (aging) has not occurred.
http://www.medtrng.com/special_operations_command_centr.htm
These concentrations are well tolerated and keep a good portion of AChE in the active state, thereby retarding the AChE aging rate.
AChE aging is particularly rapid with dimethyl phosphoryl compounds and may thwart the effective reactivation by oximes, particularly in suicidal poisoning with excessive doses.
http://pt.wkhealth.com/pt/re/tox/abstract.00139709-200322030...
--------------------------------------------------
Note added at 3 hrs (2009-05-10 15:44:36 GMT)
--------------------------------------------------
ah as a matter of fact you should keep the definition as it is, since
'AChE aging half-time' (or, just 'aging half-time')
is the exact, sufficient, and correct definiton for this process :)
--------------------------------------------------
Note added at 4 hrs (2009-05-10 16:33:48 GMT)
--------------------------------------------------
ah OK, sorry I didn't get it!
so you could use something like 'permanent inactivation' that, actually, exactly describes the meaning of 'aging' :)
http://www.google.it/search?hl=it&safe=off&num=30&q="AChE in...
--------------------------------------------------
Note added at 10 hrs (2009-05-10 22:29:02 GMT)
--------------------------------------------------
VERY interesting question!!! :D
and... after searching it (since the answerit is not at all an obious one) you are correct! but perhaps I would put it as "half the time the AChE-NA bond takes to become permanent"
see
"The ageing half-time (time for half of involved cholinesterase to age)"
http://ceaccp.oxfordjournals.org/cgi/content/full/6/6/230
(and since there is one bond for each AChE-NA complex it corresponds exactly to what you suggest)
also (considering it from the "bond point of view" ;)
"The bond between the enzyme and the nerve agent can age, a process by which the enzyme and agent become irreversibly bound. The half time for aging of sarin is 4 to 5 hours; this means that half of the bound sarin-enzyme complex can be reactivated 4-5 hours after sarin exposure by administration of the antidote. "
http://www.nj-ptc.org/training/materials/Liberty/NerveAgentA...
"Sarin's half time to aging (time at which aging has occurred in half the sarin-AChE complexes) "
http://www.gulflink.osd.mil/library/randrep/pb_paper/mr1018....
--------------------------------------------------
Note added at 12 hrs (2009-05-11 00:30:47 GMT)
--------------------------------------------------
anyway, just as an example, Italian texts keep the English term 'aging' - as (aging)' or "aging" - and accompany it with its explanation (most of the times it is "irreversible inhibition"). Sometimes 'aging' is also literally translated (i.e. the Italian term for 'getting old' is included ).
Note from asker:
| Thank you very much. I can't keep the definition as it is because I have to translate it into my native language-Polish.The word "aging", or the verb "age" in this sense does not appear in any bilingual dictionaries, so I am trying to work out its meaning. |
| Thanks for the alternative version; BTW, would it be correct to say: "the time in which half of the bonds will become permanent"? |
| Thanks once again, Mirra :-) |
4 KudoZ points awarded for this answer.
Comment: "Thanks everyone for all your help! "
12 mins
Yasutomo Kanazawa
Japan
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Works in: English to Japanese, German to Japanese, Italian to Japanese, and 3 more.
maturing time
I think aging here means maturing, therefore, it takes 10 full hours for the sarin to fully mature.
27 mins
Carol Gullidge
United Kingdom
United Kingdom
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poetically precise prose with... panache
Native in: English
Works in: French to English, Spanish to English, English
half life for aging
I'm pretty sure they mean half life, as in these examples. It's the time it takes to degrade by 50% if I remember correctly, like nuclear fuel, etc...
What is the Shelf life of Mustard and Sarin?3 posts - 2 authors
If stored dry, the half-life of Sarin (an organophosphate) is about 5 hrs. In contact with moisture or basic solutions, OP's apparently breakdown in minutes ...
www.physicsforums.com/showthread.php?t=124448 - 33k - Cached - Similar pages
The Emergency Response Safety and Health Database: Nerve Agent ...22 Aug 2008 ... DESCRIPTION: Sarin (military designation GB) is a nerve agent that is ..... (life-threatening effects or death) - mg/m3, Not established/ ...
www.bt.cdc.gov/agent/sarin/erc107-44-8.asp - 63k - Cached - Similar pages
Nanocrystalline zinc oxide for the decontamination of sarin - ElsevierThese reactions were studied at room temperature by the MAS-NMR and the data illustrated destruction reaction of the sarin with a half-life of 1.8 h on ...
linkinghub.elsevier.com/retrieve/pii/S030438940801594X - Similar pages
by TH Mahato - 2008 - Related articles
Gulf War and Health: Volume 1. Depleted Uranium, Pyridostigmine ...The half-life for “aging” is about 5 hours after sarin exposure (Sidell and Borak, 1992). Only during this period prior to aging can treatment with oxime ...
www.nap.edu/openbook.php?record_id=9953&page=169 - 95k - Cached - Similar pages
Pharmacokinetics and pharmacodynamics of obidoxime in sarin ...The elimination half-life ranged from 35 min in normal rats to 86 min in sarin-poisoned rats. Obidoxime excretion occurred predominantly by the renal route, ...
www.ionchannels.org/showabstract.php?pmid=2020972 -
What is the Shelf life of Mustard and Sarin?3 posts - 2 authors
If stored dry, the half-life of Sarin (an organophosphate) is about 5 hrs. In contact with moisture or basic solutions, OP's apparently breakdown in minutes ...
www.physicsforums.com/showthread.php?t=124448 - 33k - Cached - Similar pages
The Emergency Response Safety and Health Database: Nerve Agent ...22 Aug 2008 ... DESCRIPTION: Sarin (military designation GB) is a nerve agent that is ..... (life-threatening effects or death) - mg/m3, Not established/ ...
www.bt.cdc.gov/agent/sarin/erc107-44-8.asp - 63k - Cached - Similar pages
Nanocrystalline zinc oxide for the decontamination of sarin - ElsevierThese reactions were studied at room temperature by the MAS-NMR and the data illustrated destruction reaction of the sarin with a half-life of 1.8 h on ...
linkinghub.elsevier.com/retrieve/pii/S030438940801594X - Similar pages
by TH Mahato - 2008 - Related articles
Gulf War and Health: Volume 1. Depleted Uranium, Pyridostigmine ...The half-life for “aging” is about 5 hours after sarin exposure (Sidell and Borak, 1992). Only during this period prior to aging can treatment with oxime ...
www.nap.edu/openbook.php?record_id=9953&page=169 - 95k - Cached - Similar pages
Pharmacokinetics and pharmacodynamics of obidoxime in sarin ...The elimination half-life ranged from 35 min in normal rats to 86 min in sarin-poisoned rats. Obidoxime excretion occurred predominantly by the renal route, ...
www.ionchannels.org/showabstract.php?pmid=2020972 -
-1
44 mins
50% decrease in covalent bond effectiveness
They are talking about aging of the BOND, not the desintegration of a substance itself; thus, the usual term half-life was not used. Aging of the bond means it becoming less effective; i.e. after 5 hours, Sarin's bond with the enzyme is only 50% effective-- it probably further means that acetylcholine undergoes hydrolysis by 50% at 5 hours.
Some background info:
Sarin disrupts the nervous system by inhibiting the cholinesterase enzyme by forming a covalent bond with the particular serine residue in the enzyme which forms the site where acetylcholine normally undergoes hydrolysis. With the enzyme inhibited, acetylcholine builds up in the synapse and continues to act so that any nerve impulses are continually transmitted to the muscle which cannot relax.
Some background info:
Sarin disrupts the nervous system by inhibiting the cholinesterase enzyme by forming a covalent bond with the particular serine residue in the enzyme which forms the site where acetylcholine normally undergoes hydrolysis. With the enzyme inhibited, acetylcholine builds up in the synapse and continues to act so that any nerve impulses are continually transmitted to the muscle which cannot relax.
Note from asker:
| Thank you very much! The explanation is very helpful. |
Peer comment(s):
| disagree |
Mirra_
: it's too long to explain it in this little space, but in my opinion your explanation is completely wrong, sorry! :)
2 hrs
|
|
OK, suit yourself :)
|
48 mins
BahasaTransl8R
Quality Translation @ Reasonable Rates
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the time period within which the treatment of poisoning is still effective
After exposure to a nerve agent, enzyme inactivation will become irreversible after a period of time. This process is called aging, and occurs with a half-life that varies--happens quickly in the case of the soman-AChE complex,half of complexed agents will have aged within a couple of minutes, whereas it takes hours for comparable aging to occur for other nerve agents, such as sarin.
Once aging has occurred, oxime therapy is ineffective.
Once aging has occurred, oxime therapy is ineffective.
5 hrs
chaman4723
India
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See explanation.
The acute toxicity of the nerve agents is considered to be initiated by inhibition of acetylcholinesterase (AChE), an enzyme responsible for deactivating the neurotransmitter acetylcholine at neuronal synapses and myoneural junctions. Nerve agents phosphorylate the enzyme, thereby preventing deactivation of acetylcholine. Although the inhibited cholinesterase can be reactivated by the process of dephosphorylation, that is not possible once the nerve agent-cholinesterase complex undergoes “aging,” which is thought to happen because of a loss of an alkyl or alkoxy group...t1/2 (time required for 50% of the enzyme to become resistant to reactivation).
Re: The National Academies Press (NAP) was created by the National Academies to publish the reports issued by the National Academy of Sciences, the National Academy of Engineering, the Institute of Medicine, and the National Research Council, all operating under a charter granted by the Congress of the United States
--------------------------------------------------
Note added at 5 hrs (2009-05-10 17:30:25 GMT)
--------------------------------------------------
Thus: time required for 50% of the enzyme to become resistant to reactivation, which is represented by t1/2 is called "aging
time"
Re: The National Academies Press (NAP) was created by the National Academies to publish the reports issued by the National Academy of Sciences, the National Academy of Engineering, the Institute of Medicine, and the National Research Council, all operating under a charter granted by the Congress of the United States
--------------------------------------------------
Note added at 5 hrs (2009-05-10 17:30:25 GMT)
--------------------------------------------------
Thus: time required for 50% of the enzyme to become resistant to reactivation, which is represented by t1/2 is called "aging
time"
Example sentence:
The aging half-time for Sarin is 5 hours.
Reference comments
1 hr
Reference:
Aging of nerve agent
This might help-
AGING OF NERVE AGENT–BOUND ACETYLCHOLINESTERASE
Organophosphate nerve agents inhibit the active site of AChE, a key enzymatic regulator of cholinergic neurotransmission. As noted in Chapter 5, Nerve Agents, agent-bound AChE can be reactivated by a class of antidote compounds, the oximes, which remove the nerve agent molecule from the catalytic site of AChE.
During the attachment of the agent with the enzyme, a portion of the agent—the leaving group—breaks off. During a second, later reaction, one of the nerve agent’s alkyl groups leaves: this is the process known as aging. The rate at which this dealkylation of the AChE-bound nerve agent molecule proceeds depends on the nature of the nerve agent. Table 6-1 shows the aging half-time of each of the five chemical compounds commonly considered to be nerve agents: tabun (GA), sarin (GB), soman (GD), GF, and VX.
GB (Sarin) Human (in vivo)-aging half-time= 5 h3
AGING OF NERVE AGENT–BOUND ACETYLCHOLINESTERASE
Organophosphate nerve agents inhibit the active site of AChE, a key enzymatic regulator of cholinergic neurotransmission. As noted in Chapter 5, Nerve Agents, agent-bound AChE can be reactivated by a class of antidote compounds, the oximes, which remove the nerve agent molecule from the catalytic site of AChE.
During the attachment of the agent with the enzyme, a portion of the agent—the leaving group—breaks off. During a second, later reaction, one of the nerve agent’s alkyl groups leaves: this is the process known as aging. The rate at which this dealkylation of the AChE-bound nerve agent molecule proceeds depends on the nature of the nerve agent. Table 6-1 shows the aging half-time of each of the five chemical compounds commonly considered to be nerve agents: tabun (GA), sarin (GB), soman (GD), GF, and VX.
GB (Sarin) Human (in vivo)-aging half-time= 5 h3
Note from asker:
| Thanks, Miriam! I've been looking for this kind of info! |
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