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The role of deoxyribonuclease I in amniotic fluid during pregnancy and labour
D E Lolis1, S N Kalantaridou, T Stefos
1Department of Obstetrics and Gynaecology, University Hospital of Ioannina, Greece.
The purpose of this study was to detect the presence, and determine the normal values and the significance of DNase I in the amniotic fluid and in human placentas. Fifty-one pregnant women at 16-22 weeks of gestation and 89 women in spontaneous labour at term were recruited to the study. DNase I activity was measured in amniotic fluid and cytoplasmic extracts from the fetal portion of placentas by using a spectrophotometric technique (DNA precipitation assay) and nucleic acid electrophoresis, following degradation of the DNA by the enzyme. DNase I activity was undetectable in the placental cytoplasmic extracts. In the second trimester of pregnancy DNase I activity was detectable in amniotic fluid (2.3+/-0.64x10(5) U/l). During labour DNase I activity was also detectable, but reduced levels were observed in the presence of clear amniotic fluid, compared to second trimester levels, (1.9+/-0.44x10(5) U/l, P<0.001), whereas higher levels were found in the presence of meconium-stained amniotic fluid compared to both second trimester and clear amniotic fluid at labour (11.4+/-4.1x10(5) U/l, P<0.001 and P<0.001, respectively). Three out of 17 fetuses with meconium-stained amniotic fluid (18%) developed perinatal infection. In conclusion, the detection of DNase I activity in the amniotic fluid of second and third trimester indicates a physiological role in human pregnancy. DNase I activity normally decreases at term, compared to second trimester levels, but increases significantly in the presence of meconium.
The purpose of this study was to detect the presence, and determine the normal values and the significance of DNase I in the amniotic fluid and in human placentas. Fifty-one pregnant women at 16-22 weeks of gestation and 89 women in spontaneous labour at term were recruited to the study. DNase I activity was measured in amniotic fluid and cytoplasmic extracts from the fetal portion of placentas by using a spectrophotometric technique (DNA precipitation assay) and nucleic acid electrophoresis, following degradation of the DNA by the enzyme. DNase I activity was undetectable in the placental cytoplasmic extracts. In the second trimester of pregnancy DNase I activity was detectable in amniotic fluid (2.3+/-0.64x10(5) U/l). During labour DNase I activity was also detectable, but reduced levels were observed in the presence of clear amniotic fluid, compared to second trimester levels, (1.9+/-0.44x10(5) U/l, P<0.001), whereas higher levels were found in the presence of meconium-stained amniotic fluid compared to both second trimester and clear amniotic fluid at labour (11.4+/-4.1x10(5) U/l, P<0.001 and P<0.001, respectively). Three out of 17 fetuses with meconium-stained amniotic fluid (18%) developed perinatal infection. In conclusion, the detection of DNase I activity in the amniotic fluid of second and third trimester indicates a physiological role in human pregnancy. DNase I activity normally decreases at term, compared to second trimester levels, but increases significantly in the presence of meconium.