Transepidermal Water Loss in Newborns Within the First 24 Hours of Life: Baseline Values and Comparison with Adults

The measurement of transepidermal water loss (TEWL) is important for evaluating the integrity of the barrier function of the stratum corneum. Normal TEWL values in healthy adults and in children ages 2 and older are well known, but few studies have been performed in infants and neonates. TEWL in healthy neonates younger than 24 hours old was assessed and compared with that of an adult study population. We also studied possible correlations between this parameter, gestational age, and mode of delivery. A prospective study was conducted in healthy newborns. The areas tested were the volar forearm and the popliteal fossa. Ninety‐nine healthy newborns were enrolled and 33 healthy adults were analyzed as controls. Statistically significant differences were noted between newborns and adults in TEWL (p < 0.01). Newborns had a much higher mean TEWL than adults. Differences in the morphology and physiology between newborn and mature skin can explain the higher TEWL in newborns. Higher TEWL could also be due to the sudden functional adaptation of the skin immediately after delivery, when the newborn transits from a liquid to the dry, gaseous extrauterine environment. Functional evaluation of the neonatal skin barrier is important mainly because maintaining skin integrity facilitates cutaneous adaptation.     

Looking at a predator with the left or right eye: Asymmetry of response in lizards

Studies carried out with the common wall lizard (Podarcis muralis) revealed preferential use of the left eye during responses to predatory threat in laboratory settings and in the wild. Here we tested lizards under monocular conditions of vision, using temporary eye-patching. Lizards were facing a (simulated) predatory threat laterally, from the side of the non-patched eye. Results showed that lizards with the left eye uncovered during predatory threat used the left eye to monitor the predator, whereas lizards with the right eye uncovered nonetheless tried to use the covered left eye. Moreover, lizards frequently tried to change the eye exposition, making a body C-bend behaviour. Right-eyed lizards showed more frequent and faster C-bending responses than left-eyed lizards, trying to monitor the predator with the left eye even though it was patched. Results fit with asymmetries in spontaneous eye use observed in laboratory conditions and in the wild in this species, confirming that structures located on the right side of the brain (mainly served by the left eye) predominantly attend to predatory threat.     

Retinal Laser Damage Thresholds as a Function of Image Diameter

The eyes of rhesus monkeys were exposed to argon (514.5 nm) and ruby (694.3 nm) laser irradiation using various retinal image diameters which were estimated by microphotometric techniques. The experimental design for both wavelengths produced image diameters of 40μ to 50μ for the “minimal” case and approximately 500μ to 1,000μ for the larger irradiance series employed. Extramacular retinal exposure sites were examined by ophthalmoscopic and histopathological techniques. Flat preparations of the pigmented epithelium and sensory layers of the retina were utilized in the confirmation of damage at low power levels. All data were statistically analyzed to establish trends, and results were compared for the wavelengths employed. Results indicate that retinal damage is primarily dependent on energy distribution as a function of image diameter and exposure duration.     

Butyrate Induces Glutathione S-Transferase in Human Colon Cells and Protects From Genetic Damage by 4-Hydroxy-2-Nonenal

Butyrate, one of the major products of gut fermentation, is known to inhibit proliferation, induce apoptosis and differentiation, and increase phase II enzyme activities in tumor cells, whereas little information is available on protective effects in less-transformed colon cells. The aim of this study was to investigate whether the chemoprotective mechanism of glutathione S-transferase (GST) induction by butyrate could also play a role in earlier stages of colon carcinogenesis and whether chemoresistance of cells toward the endogenous genotoxic risk factor 4-hydroxy-2-nonenal (HNE) could be a consequence of butyrate treatment. As cell models, we used the human tumor cell lines HT29 and HT29 clone 19A, a differentiated subclone with properties resembling primary colon cells. We determined the expression of GSTP1 protein (enzyme-linked immunosorbent assay), the major GST in HT29, GSTP1 mRNA (Northern blotting), GST activity, intracellular glutathione, and total protein. The genotoxic impact of HNE (100-200 μM) was compared in butyrate-treated and nontreated cells using single-cell microgel electrophoresis. Our results show that GSTP1 mRNA, GSTP1 protein, GST activity, and total protein were increased (1.2- to 2.5-fold) and glutathione levels were maintained after 24- 72 h of incubation with 4 mM butyrate. Moreover, a marked reduction of HNE-induced genotoxicity was caused by preincubation with butyrate. Butyrate also induced the phosphorylation of extracellular signal-regulated kinases (ERK1/2, Western blotting) after 5-30 min, which indicates a regulation of GST expression by this signal pathway. Most effects were greater in HT29 parent cells than in clone cells. In conclusion, butyrate enhances expression of GST and other proteins in both cell lines, which leads to an enhanced chemoprotection, reducing the impact of HNE genotoxicity. Thus butyrate could play a role in early and later stages of cancer prevention by reducing exposure to relevant risk factors.