drpkaur
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what happens in pyruvate carboxylase deficiency????plz explain.
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| vallia
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I'll do my best...
First rememnber the steps of gluconeogenesis, formation of new glucose from glycerol, lactate, AA.
Pyruvate--->OAA--->PEP--->2Pglycerate--->3Pglycerate--->1, 3bisPglycerate-->glyceraldehide3P-->fructose1,6bisP--->fructose6P- -->glucose6P--->glucose
now most of the steps from glycolysis are revesible but 3 of themare irreversible. Those reaction must be circumvented in favor of formation of glucose. Actually 4 reaction..these are
1. pyruvate-----OAA
2. fructose1,6bisP---->fructose6P
3. glucose6P--->glucose
Now pyruvate carboxilase is the enzime that carboxylates pyruvate to OAA. Then OAA is converted to PEP by PEP carboxykinase.pyruvate carboxilase is located in mithocondria and the others enzy,e in citosol
In pyruvate carboxilase deficiency, we have low levels of this enzyme so gluconeogenesis is blocked here, leading to accumulation of pyruvate. Others way of transformation pyruvate include transformation in lactate, and transformation of pyruvate in acetylCoa, entering in CAA and Fatty acid synthesis
pyruvate<--->lactate, and this reaction is catalise by lactate dehydrogenase and elevated levels of pyruvate favors formation of lactate.
So we have lactic acidosis in this disease. Also periodic hypoglicemia, failure to thrive, vomiting and hypotonia and ataxia. i don't know why ataxia but that's it.
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| drpkaur
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nice explanation .thanx vallia...so in short PC deficiency leads to lactic acidosis,periodic hypoglycemia,vomiting ,mental retardation,hypotonia,ataxia,marked psychomotor delay,seizures plus malignant hyperthermia if they are administered halothane as anesthetic...
another ques how do you differentiate b/n PC deficiency and PDH deficiency..
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| young_doc
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PDH deficiency should not give fasting hypoglycemia. And would give Lactic acidosis with glucose ingestion.
A better differential would be PC deficiency & G6Phosphatase deficiency! Anyone?
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| drpkaur
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Hi young_doc,
In G6Phospahatase deficiency i.e Von-gierke's disease(glycogen storage disease type 1) -symptoms-severe fasting hypoglycemia,hepatomegaly,fatty liver,hyperlipidemia,hyperlacticacidemia,hyperuricemia,growth retardation,progressive renal disease,increased glycogen stored but normal glycogen structure..
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| vallia
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no ataxia and hypotonia in von Gierke
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