Biophysical properties of dry atopic and normal skin with special reference to effects of skin care products

During recent years several highly developed non-invasive methods for evaluation of skin physiology and pathology have been introduced. Against this background, the present studies were undertaken with the primary aim of assessing the effects of various skin care products on some properties of the skin. Skin topography was measured by profilometry on skin replicas, friction with a newly developed friction instrument, capacitance with a Corneometer, and barrier function both with an Evaporimeter to assess transepidermal water loss (TEWL) and by application of an irritant followed by measurement of the resulting irritative reaction. Initially some of the techniques were used to further characterize the differences between dry atopic skin and normal skin. Dry skin exhibits increased values of roughness parameters and a reduced number of topographical peaks. TEWL is increased, indicating impaired barrier function. The friction and capacitance are lower and correlate significantly to each other, whereas TEWL does not appear to relate to either of these parameters. The use of a scrub cream removes the outermost part of the stratum corneum, resulting in a smoother skin. Application of moisturizers modifies the frictional response of the skin. The friction instrument gave results comparable to those of panelists trained in sensory evaluation. The study suggests that measurement of skin friction can be used to predict the degree of liking of moisturizers. Furthermore, moisturizers increase the skin hydration. They provide water directly to the skin from their water phase. Skin hydration also increases with increased degree of occlusion, as measured as a decrease in TEWL. Moisturizers may also alter the diffusional resistance of the stratum corneum and reduce the skin susceptibility to the surfactant sodium lauryl sulphate (SLS). Lipids in moisturizers may influence already developed SLS-induced irritation. A significantly lower degree of irritation was found in areas treated with canola oil and its sterol-enriched fraction than in an area treated with water. These findings emphasize that skin care products do not only form an inert, epicutaneous layer, but that they may penetrate and influence the structure and function of the skin.

Scaling, dry skin and gender. A bioengineering study of dry skin

Dry skin and scaling was studied in a group of 72 healthy volunteers by using subjective self-assessment and by clinical assessment by a dermatologist, as well as application of noninvasive bioengineering techniques to measure scaling and epidermal hydration. The study revealed that 67% of the volunteers had subjective complaints, while only 5.6% had definite clinical signs of dry skin at the time of examination. Subjective complaints were more common in women than in men (p < 0.001), though neither clinical nor objective measurements showed any sex difference, which suggests that other factors may play a role in the way men and women perceive dry skin. Subjective and clinical scores were correlated (p < 0.02), though neither was significantly correlated to objective measurements. Grading of skin scaling on D-squame tapes correlated with densitometry of the tapes (p < 0.001), as did the electrical capacitance (p < 0.001). Both clinical and objective methods can identify dry skin. However, the study showed that in healthy persons a number of irrational factors play a role in the use of moisturizers, and while these factors cannot be measured, they must be taken into account. Healthy, but dry skin is a vaguely defined clinical entity, which may explain the generally poor correlation between the two methods. This underlines the need for several methods to be used simultaneously in order to elicit complementary information.

Recordings of pre- and postoperative sympathetic skin response in patients with palmar hyperhidrosis

Transthoracic endoscopic sympathectomy is an accepted standard surgical treatment for hyperhidrosis palmaris. During the past 4 years, more than 500 patients underwent this kind of surgical treatment at our institution with a 98% success rate. About 50% of cases were found to have compensatory sweating. We measured the sympathetic skin response (SSR) and R-R interval variation (RRIV) in 38 normal control subjects, and 50 consecutive patients with palmar hyperhidrosis before and 2 weeks after transthoracic endoscopic T2-3 sympathectomy. Before sympathectomy SSR was absent in 36% of patients on deep inspiratory stimulation and in 20% on electrical stimulation. After T2-3 sympathectomy, SSR in the palms was absent in 64% of patients with deep inspiration stimulation and in 76% on electrical stimulation. A decrease in the SSR amplitude in the soles was found in 40% on deep inspiration and in 54% of patients on electrical stimulation. RRIV was not significantly influenced 2 weeks after sympathectomy. The high abnormal rate of SSR in the patient group indicated that an abnormal regulation of the sudomotor control center played an important role in palmar hyperhidrosis.