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Biomedical subjects

S B Hoath

Publications and source records attributed to S B Hoath.

59 records · Page 4Linked to original sources
PubMedDate not supplied

Changes in diapered and nondiapered infant skin over the first month of life.

Time- and site-dependent differences in epidermal barrier properties were investigated over the first 28 days of life in healthy term newborn infants. Diapered and nondiapered skin sites were contrasted to the volar forearm of adults (mothers). Thirty-one term infants were evaluated in the hospital on postnatal day 1 and at home on days 4, 7, 14, 21, and 28 for a total of six visits. Measurements included baseline skin hydration, continuous capacitive reactance, peak water sorption, rate of water desorption, skin pH, skin temperature, and environmental conditions. Changes in epidermal barrier properties over the first 4 weeks of life included an increase in surface hydration, a decrease in transepidermal water movement under occlusion, a decrease in surface water desorption rate, and a decrease in surface pH. Diapered and nondiapered regions were indistinguishable at birth but exhibited differential behavior over the first 14 days, with the diapered region showing a higher pH and increased hydration. Maternal measurements remained constant throughout the period. We conclude that healthy newborn skin undergoes progressive changes in epidermal barrier properties over the first 28 days. Adult skin testing does not replicate newborn skin during the first month of life.

Adult↗
PubMedDate not supplied

Characterization of vernix caseosa as a natural biofilm: comparison to standard oil-based ointments.

The application of occlusive films and oil-in-oil ointments has been reported to improve epidermal barrier function in very low birthweight, preterm infants. Such infants have a structurally immature stratum corneum and lack a surface coating of vernix caseosa. In this study we examined the short-term effects of topical application of vernix caseosa to human skin and contrasted these effects with commonly used ointments and water-in-oil emulsions. Specifically, vernix, Eucerin(R), Aquaphor(R), and petrolatum were applied to the volar skin surface of adult volunteers. Surface electrical capacitance (SEC) and transepidermal water loss (TEWL) were measured as indices of surface hydration. Sorption-desorption profiles were performed to determine skin surface hydrophobicity. Particular attention was given to monitoring the acute (0-120 minutes) changes following vernix treatment in order to compare these effects with earlier reports on the rate of skin surface drying in newborn infants following birth. Immediately after vernix application there was an increase in the rate of water loss from the skin surface. Relative to control skin and skin treated with the ointments and water-in-oil emulsions, the application of vernix to freshly bathed human skin resulted in a unique profile of temporal change in baseline surface hydration, moisture accumulation, and water-holding capacity. These results demonstrate major differences between human vernix and standard oil-based topical ointments. The results provide a framework for discussing the various properties of topical barriers applied to the very low birthweight infant.

Adult↗
PubMedDate not supplied

Assessment with the dermal torque meter of skin pliability after treatment of burns with cultured skin substitutes.

The assessment of visco-elastic (V-E) properties in cutaneous scars is critical to reduction of impairment and restoration of function after grafting of excised burns. Cultured skin substitutes (CSS) that consist of autologous keratinocytes and fibroblasts attached to biopolymer substrates are alternatives for permanent closure of excised, full-thickness burns, but assessment of scarring has been subjective. V-E properties of CSS were measured with a Dia-Stron Dermal Torque Meter (DTM 310, Dia-Stron, Ltd, Broomall, Pa), which applies a constant torque (10 mNm) for a fixed interval (10 seconds) and measures rotational deformation and recovery. Parameters of skin deformation were measured in patients (n = 10) after grafting of CSS or meshed skin autograft. Native human skin (NHS) of healthy volunteers (n = 13) served as the control. Skin healed after treatment with CSS or autograft was evaluated for 1 year or longer after grafting. Elastic stretch (Ue), viscous stretch (Uv), total extensibility (Uf), elastic recovery (Ur), total recovery (Ua), and residual plasticity (R) were measured as degrees of rotation, were tested for significance (P < .05) by Student t test comparisons between treatment groups and controls, and were subjected to regression analysis. Assessment of burn scar with the Dermal Torque Meter detected time-dependent increases of all individual parameters of V-E properties for both CSS and autograft during the first year after grafting. At 1 year or later, no statistical differences were found between CSS and autograft for individual parameters, but Ue and Ur for autograft were significantly lower than for NHS. At 1 year or longer, autograft was significantly different from CSS or NHS, with a greater ratio of Uv to Ue, and both graft types had a lower ratio of Ur to Uf than NHS had. These results suggest that instrumental measurement of scar pliability may increase objectivity in assessment of patient recovery and establish an absolute scale for quantitative analysis of V-E properties in skin after grafting of conventional or alternative skin substitutes.

Biocompatible Materials↗
PubMedDate not supplied

Accurate micromethod of neonatal blood sampling from peripheral arterial catheters.

Blood sampling from peripheral arterial catheters is an important, but inadequately standardized, technique in neonatal intensive care. In this study two peripheral arterial sampling methods were evaluated in a neonatal animal model. One commonly used method (the drip technique) involves inserting a needle into the hub of the peripheral arterial catheter and discarding up to 10 drops of infusate fluid and blood before the sample is collected. This method was compared with a new micromethod where two needles are used (two-needle technique). Blood gas values in the peripheral samples were compared with control values drawn from a femoral artery catheter. Accuracy of peripheral arterial PCO2 and total blood loss constituted the final study variables. The results demonstrated that the two needle technique was more accurate, yielding peripheral arterial PCO2 values that were 98% of control values. Withdrawal of fewer than six drops of infusate fluid and blood with the drip technique resulted in spuriously low PCO2 values. The new technique also resulted in significantly less total blood loss per sample compared with the drip technique (189 +/- 3 microliters vs 398 +/- 3.8 microliters, mean +/- SEM, p < 0.01). We conclude that the two-needle micromethod is an accurate technique for blood sampling from peripheral arterial catheters and is particularly appropriate for low-birth-weight infants in whom minimization of blood loss is desirable.

Animals↗