Wernicks Korsakoff; pyruvate dehydrogenase or transketolase? - USMLE Forums
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Old 01-22-2012
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Biochemistry Wernicks Korsakoff; pyruvate dehydrogenase or transketolase?

in wernicks encephalopathy it is due to vit b1 def. but that affect pyruvate dehydrogenase or transketolase enz.??
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hope this is the answer you are looking for :

B1 or thiamine pyrophosphate is just like lipoic acid, coenzyme A, riboflavin (FAD) and niacin (NAD) a coenzyme for Pyruvatedehydrogenase (Pyruvate ->AcetylCoA), alpha-ketoglutaratedehydrogenase (alphaketoglut -> succinylCoA) and Transketolase.

this is why if you have a patient with neraly-wernicke-korsakoff and you administer only sailine with glucose you 'produce' wernicke-korsakoff because you use the last bitt of b1 that's still there for the metabolisation of glucose via Pyrovatdehydrogenase.
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Originally Posted by MedPharm View Post
hope this is the answer you are looking for :

B1 or thiamine pyrophosphate is just like lipoic acid, coenzyme A, riboflavin (FAD) and niacin (NAD) a coenzyme for Pyruvatedehydrogenase (Pyruvate ->AcetylCoA), alpha-ketoglutaratedehydrogenase (alphaketoglut -> succinylCoA) and Transketolase.

this is why if you have a patient with neraly-wernicke-korsakoff and you administer only sailine with glucose you 'produce' wernicke-korsakoff because you use the last bitt of b1 that's still there for the metabolisation of glucose via Pyrovatdehydrogenase.

well explained ... in addition i guess if you are trying to solve a Qs saying how do measure B1 def then its transketolase level in erythrocyte , though it affects PDH too ......
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thanks both and y I solved this q today but which made me confused , in wernicks it is exactly which enz. does not work transketolase or pyruvate dehydrogenase??
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hey i found that transketolase is more sensitive than PDH and is affected more , there is decline in it even in asymptomatic pts .... its on pubs.niaaa.nich/gov site .... what was the ans in your Qs ???????
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hey i found that transketolase is more sensitive than PDH and is affected more , there is decline in it even in asymptomatic pts .... its on pubs.niaaa.nich/gov site .... what was the ans in your Qs ???????
yes it is transketolase also , but is it responsible for wernicks or is it the pyruvate dehydrogenase???
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yes it is transketolase also , but is it responsible for wernicks or is it the pyruvate dehydrogenase???
there is no specific enzyme responsible for wernicks , but transketolase is more sensitive and get affected first .... thus appears to be a better ans in the end all enzymes are affected ... transketolase def decreases ribose phosphate needed for dna synthesis and glutathione by HMP while PDH is needed for myelin and ATP ... but still transketolase is the ans it seems
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Wouldn't be PDH? This enzyme is before entering the Krebs cycle, the one that, if no B1, we have deviation to make lactic acid? I think that is PDH and no transketolase the one that is responsible for this pathology.
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I read it online that transketolase is the most sensitve of the three and its also logical i feel G-6-P is used by G6PD in the very beginning of the glycolysis pathway and would be affected first and even while measuring B1 level we check for erythrocyte Transketolase levels .... its level is low even in mild def and asymptomatic pts making it a sensitive test ...
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