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Hepatic polyamine metabolism in children with Reye's syndrome
A Mukhopadhyay1, D R Deshmukh, A P Sarnaik
1Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit.
Abstract:
Acute mitochondrial insult has been suggested as a primary reason for the clinical, histopathological and biochemical abnormalities seen in Reye's syndrome. However, the etiology of mitochondrial dysfunction has not been identified. Polyamines have been known to alter the mitochondrial structure and function. Influenza infection may cause an increase in ornithine decarboxylase activity and thereby channel ornithine for polyamine biosynthesis, leading to mitochondrial dysfunction in Reye's syndrome. To test this hypothesis, the hepatic concentrations of polyamines, polyamine-metabolizing enzymes and urea cycle enzyme activities in Reye's syndrome patients were determined and compared with patients who died from illnesses other than Reye's syndrome. The hepatic concentration of putrescine, spermidine and spermine were increased in Reye's syndrome patients. The activity of ornithine decarboxylase was elevated but, due to the small number of samples, these values did not reach statistical significance. Ornithine carbamoyltransferase activity was decreased in the liver of Reye's syndrome patients. Our results suggest that increased synthesis of polyamines from ornithine may initiate mitochondrial injury in Reye's syndrome.
Insights
Increased polyamine synthesis may cause mitochondrial injury in Reye's syndrome. This study found elevated polyamines and altered enzyme activity in Reye's syndrome patients, suggesting a link to disease pathogenesis.
Area of Science:
- Biochemistry
- Pathology
- Molecular Biology
Background:
- Reye's syndrome involves mitochondrial dysfunction, but its cause is unknown.
- Polyamines can affect mitochondrial structure and function.
- Influenza infection might increase polyamine synthesis, potentially causing Reye's syndrome.
Purpose of the Study:
- To investigate the role of polyamines in Reye's syndrome.
- To compare polyamine levels and enzyme activities in Reye's syndrome patients versus controls.
Main Methods:
- Measured hepatic polyamine concentrations (putrescine, spermidine, spermine).
- Assessed polyamine-metabolizing enzymes, including ornithine decarboxylase.
- Determined urea cycle enzyme activities, specifically ornithine carbamoyltransferase.
Main Results:
- Reye's syndrome patients showed increased hepatic concentrations of putrescine, spermidine, and spermine.
- Ornithine decarboxylase activity was elevated, though not statistically significant due to sample size.
- Ornithine carbamoyltransferase activity was decreased in Reye's syndrome livers.
Conclusions:
- Elevated polyamine synthesis from ornithine may initiate mitochondrial injury in Reye's syndrome.
- Polyamines are implicated in the pathogenesis of Reye's syndrome.