Effects of blue light phototherapy on DNA integrity in preterm newborns.

In previous studies, exposure to phototherapy, but not oxygen therapy, resulted in damage to genetic material in newborns. The objective of this study was to determine whether micronucleated erythrocytes (MNE) increased in preterm newborns (PNBs) who were exposed to blue light phototherapy lamps. MNE of mature organisms are rapidly eliminated by the spleen, and the presence of MNE has been related to immaturity in some species. Furthermore, PNBs present spontaneous MNE. Blood samples were taken from 17 PNBs at birth to establish baseline frequencies (0 h). After beginning blue light phototherapy, blood samples were obtained from 11 of these PNBs at 24-h intervals for 96 h, after the baseline sample. MNE and micronucleated polychromatic erythrocytes (MNPCE) were counted. The basal values of MNE and MNPCE from 17 PNBs were 0.62 ± 0.48 and 1.52 ± 1.28 (‰), respectively, and no increase in MNE or MNPCE was observed in the serial samples of 11 PNBs exposed to blue light and oxygen therapies, though previous studies reported increases using other types of lamps. In conclusion, under the conditions described no increase in the number of MNE or MNPCE was observed in the peripheral blood of PNBs exposed to blue light phototherapy.

Micronucleated erythrocytes in preterm newborns exposed to phototherapy and/or oxygentherapy.

Preterm newborns (PNBs) have an immature antioxidant defense system, and this makes them more susceptible to oxidative stress generated by postnatal treatments. The objective was to determine whether micronucleated erythrocytes increase in PNB by postnatal treatments such as oxygentherapy and phototherapy. We counted micronucleated erythrocytes and micronucleated polychromatic erythrocytes as DNA damage in 72 blood samples of PNB at 26-36 weeks of gestation, taken between 1 and 84 h after birth. We assume that more time passed between sampling and birth would correspond to greater time of exposure to oxygen (37 cases) and phototherapy plus oxygen (35 cases). In the PNB only exposed to oxygen, the differences were not significant, while there was a significant increase in micronucleated polychromatic erythrocytes with increasing exposure time in those treated with phototherapy plus oxygen. In conclusion, our results suggest that the MN increase from phototherapy can be observed in peripheral blood erythrocytes of PNB.