Measurement of transepidermal water loss in Tanzanian cot-nursed neonates and its relation to postnatal weight loss

Commonly Employed African Neonatal Skin Care Products Compromise Epidermal Function in Mice

BACKGROUND

Neonatal mortality is much higher in the developing world than in developed countries. Infections are a major cause of neonatal death, particularly in preterm infants, in whom defective epidermal permeability barrier function facilitates transcutaneous pathogen invasion. The objective was to determine whether neonatal skin care products commonly used in Africa benefit or compromise epidermal functions in murine skin.

METHODS

After twice-daily treatment of 6- to 8-week-old hairless mice with each skin care product for 3 days, epidermal permeability barrier function, skin surface pH, stratum corneum hydration, and barrier recovery were measured using a multiprobe adapter system physiology monitor. For products showing some benefits in these initial tests, the epidermal permeability barrier homeostasis was assessed 1 and 5 hours after a single application to acutely disrupted skin.

RESULTS

All of the skin care products compromised basal permeability barrier function and barrier repair kinetics. Moreover, after 3 days of treatment, most of the products also reduced stratum corneum hydration while elevating skin surface pH to abnormal levels.

CONCLUSION

Some neonatal skin care products that are widely used in Africa perturb important epidermal functions, including permeability barrier homeostasis in mice. Should these products have similar effects on newborn human skin, they could cause a defective epidermal permeability barrier, which can increase body fluid loss, impair thermoregulation, and contribute to the high rates of neonatal morbidity and mortality seen in Africa. Accordingly, alternative products that enhance permeability barrier function should be identified, particularly for use in preterm infants.

Effects of hypoglossal and facial nerve injuries on milk-suckling

Functional roles of the perioral anatomical structures involved in breastfeeding were examined in newborn rat pups in which the hypoglossal (XII) and facial (VII) nerves had been resected at the neonatal stage. The XII nerve controls tongue movement and is comprised of two functionally distinct branches: the medial branch related to protrusion of the tongue and the lateral branch related to its retraction. Newborn rat pups with bilateral resection of either of the XII nerve components (main trunk: XII-trunk; medial branch: XII-med; lateral branch: XII-lat) failed to suckle milk and did not survive. Unilateral XII nerve-resected neonates showed different milk-suckling capabilities, which thus resulted in differences in survival rate (XII-trunk: 38%; XII-med: 24%; XII-lat: 92%) and postnatal growth during the postnatal 3 weeks until P21. Unilateral and bilateral resections of the VII nerve innervating the buccolabial musculature produced lowered suckling capabilities and retarded postnatal growth, although all pups showed 100% survival. The results indicate a crucial role of the tongue, especially of protruding muscular elements innervated by the XII-med nerve, in breastfeeding. The results also indicate differential effects of the VII and XII nerve components on suckling capability, survival, and postnatal growth of newborn rat pups.

Skin barrier, hydration, and pH of the skin of infants under 2 years of age

The goal of this study was to instrumentally evaluate the skin of healthy infants and to compare it to adult skin. A total of 70 infants, 45 girls and 25 boys, ages 8-24 months, and 30 healthy women were studied by means of transepidermal water loss (TEWL), capacitance, and pH measurements at two different skin sites, the volar forearm and the buttocks. No significant differences in TEWL were found between infants and adults, either on the buttocks or on the volar forearm. On the contrary, capacitance values were higher in infants. Their skin also appeared less acid than that of adults, with high statistical significance. No TEWL, capacitance, or pH variations were observed in infants according to sex and age. On the basis of the above data, the skin of infants 8-24 months of age shows functional signs of immaturity. This may lead to an increased permeability and a reduced capacity for defense against chemical and microbial aggression.