CHANGES IN STRATUM CORNEUM-WATER INTERACTIONS FOLLOWING BIRTH IN THE NEWBORN INFANT • 1021

Abstract

The outermost layer of the skin, the stratum corneum (SC), is a thin, flexible, polymeric envelope required for survival in a terrestrial environment. Evidence from newborn animals demonstrates that the SC manifests a range of unique water interactions at birth including a hydrophobic surface mantle, integral barrier lipid lamellae, and spontaneous proteolysis of structural proteins, such as filaggrin, to form smaller water binding molecules necessary for polymer plasticization. In the present study, we evaluated the background of these interactions by quantifying changes in SC hydration, water flux, and surface hydrophobicity (water desorption) over the first 16h of life in 86 term infants. Unit measurement of surface electrical capacitive reactance (cru) served as the primary index of hydration state(Pediatrics 96:688-692, 1995). A separate study looking at the effect of occlusion was also performed using a plastic thermal wrap to occlude the lower body after birth. The results demonstrate 1) a progressive fall in surface hydration from 2h to 16 h after birth (113±3 to 105±5 cru's, respectively, p < 0.05), 2) a decrease in transepidermal water movement measured as the slope of the continuous capacitance curves(0.96±0.12 at 2h of age to 0.32±0.09 cru's/sec at 16h, p < 0.01), 3) an increase in surface water desorption (-7±0.6 at 2h of age to -12±1 cru's/sec × 1000 at 16h, p < 0.01); 4) higher baseline hydration following occlusion of the suprapubic region at 2h of age compared to the chest (135±7 to 120±4 cru's, respectively, p<0.01); and 5) increased transepidermal water movement following occlusion(2.86±0.34 compared to 1.21±0.16 cru's/sec, p<0.01).