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Monitoring erythrocyte free radical resistance in neonatal blood microsamples using a peroxyl radical-mediated
Insights
Oxidative stress impacts premature infants. A new micromethod accurately measures erythrocyte antioxidant defenses, correlating with tocopherol levels and aiding preterm infant monitoring.
Area of Science:
- Biochemistry
- Neonatology
- Pediatric Medicine
Background:
- Oxidative stress is linked to diseases in premature infants.
- Erythrocyte membrane antioxidant defenses can be assessed via hemolysis assays.
- The free radical generator AAPH (2,2'-azobis (2-amidinopropane)dihydrochloride) is used to induce hemolysis.
Purpose of the Study:
- To develop a micromodification of the AAPH-induced erythrocyte hemolysis test.
- To assess erythrocyte radical resistance in term and preterm infants.
- To correlate hemolysis resistance with plasma tocopherol levels.
Main Methods:
- A micromodification of the AAPH-induced hemolysis test was developed.
- The test requires only 15 microliters of erythrocytes from capillary blood samples.
- Time to 50% hemolysis (T50%) was measured to characterize radical resistance.
Main Results:
- T50% values in healthy term infants were lower than in adults initially, then increased.
- A significant correlation was found between T50% values and plasma tocopherol levels.
- Preterm infants showed higher T50% values than term infants on the first day of life.
Conclusions:
- The micromodification simplifies monitoring of erythrocyte antioxidant defenses in preterm infants.
- This method allows for frequent, minimally invasive assessment of antioxidant status in vulnerable neonates.
- Findings highlight the utility of this test for managing oxidative stress in sick preterm infants.
Abstract:
Inadequate resistance to oxidative stress has been implicated in several diseases of premature children. Antioxidative defences at the membrane level can be studied by measuring haemolysis induced through exposure of erythrocytes to the free radical generator AAPH (2,2'-azobis (2-amidinopropane)dihydrochloride). We developed a micromodification of this haemolysis test requiring only 15 microl of erythrocytes derived from capillary blood samples. The time needed for 50% haemolysis (T50%) was used to characterize radical resistance of erythrocytes. T50% results in adult samples were highly reproducible. T50% values in healthy term infants on the first 2 d of life were lower than in adults (p < 0.001), but increased to the same level thereafter. A correlation was found between T50% values and plasma tocopherol levels as determined in plasma of each of the capillary blood samples (p < 0.001). On the first day of life T50% results in preterm infants (n = 20) were higher than in term infants (p < 0.001). It was easy to monitor T50% results and plasma tocopherol levels in preterm infants that were not at all burdened by the sampling method, almost daily over several weeks. The micromodification presented simplifies monitoring of antioxidative defences in sick preterm infants.