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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of human back versus arm skin region for its suitability to test weak irritants (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Skin research and technology 2 (1996), S. 0 
    Details
    ISSN: 1600-0846
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background/aims: Large-scale comparative screening of der-matological and cosmetic products require non-invasive bioengineering methods which give reproducible results that can be statistically analyzed. To determine the most suitable test region for testing irritating substances, the response of the skin to the weak irritant sodium lauryl sulphate (SLS) was measured on standardized locations on the forearm and back. Furthermore, using 3 bioengineering methods, we aimed to establish the most sensitive method to measure skin response to SLS.Methods: The baseline measurements of transepidermal water loss (TEWL), cutaneous blood flow (CBF) and skin colour a*-value were performed at 6 standardized locations on the volar forearms and at 12 locations on the back on 2 consecutive days, day 1 and 2, in 9 healthy volunteers. On day 2, 9 out of the 18 sites were exposed to 0.5% SLS by occlusive 24-h patches and the skin response was evaluated on days 3 and 4.Results: For TEWL, CBF and a*-value, no significant regional variations were found within individuals at any time on the arm locations and on the back locations. However, significant inter-individual variation was found. At the back on day 4, a slightly higher skin response to SLS was found compared to that found on the forearms as measured by TEWL and the a*-value. Of the 3 bioengineering methods used, TEWL was the most sensitive method to detect cutaneous response to the weak irritant used. TEWL measurements on days 1 and 2 performed at the 6 standardized locations on the volar forearms inside and outside a specially constructed air convection protection box, showed no relevant differences in measured TEWL values.Conclusion: Both the forearms and the back were found to be suitable sites for irritancy testing. Since considerable differences in mean reactivity between subjects have been observed the use of large numbers of subjects in predictive irritant patch testing is required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0846.1996.tb00062.x
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  • 2
    Electronic Resource
    Electronic Resource
    Barrier function parameters in various keratinization disorders: transepidermal water loss and vascular response to hexyl nicotinate (1993)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 129 (1993), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In this study, we characterized the stratum corneum barrier function in 39 patients with various keratinization disorders (autosomal dominant ichthyosis vulgaris [ADI] [n=7]. X-linked recessive ichthyosis [XRI] [n=6], autosomal recessive congenital ichthyosis [C1] [N=10]. dyskeratosis follicularis [Darier's disease: DD] [n=8], erythrokeratoderma variabilis [EKV] [n=8]). and 21 healthy volunteers, using two non-invasive methods: transepidermal water loss (TEWL) measuring outward transport of water through the skin by evaporimetry. and the vascular response to hexyl nicotinate (HN) penetration into the skin as determined by laser-Doppler flowmetry.Significantly increased TEWL values were found on the volar forearm in all three forms of ichthyosis, compared with the healthy control group, with the highest TEWL values in the CI group. The penetration of HN on the volar forearm was accelerated in patients with ADI. XRI and CI, as indicated by a shorter lag time (to) between HN application and initial vascular response. However, differentiation between CI and the other ichthyoses was not possible by this method. When using both methods in DD and EKV. no differences compared with the healthy controls could be detected on the volar forearm, where the skin was principally unaffected: only the measurements from the affected skin on alternative sites demonstrated significantly increased TEWL values. In ADI and CI. however, normal-appearing skin also showed impaired values.We conclude that both TEWL and the vascular response to penetration of HN are suitable methods to monitor the skin barrier function in keratinization disorders, and are helpful in discriminating between these disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2133.1993.tb00482.x
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  • 3
    Electronic Resource
    Electronic Resource
    Skin barrier function in healthy volunteers as assessed by transepidermal water loss and vascular response to hexyl nicotinate: intra- and inter-individual variability (1993)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 128 (1993), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study assesses the variability of two non-invasive methods of measuring stratum corneum barrier function in vivo. Transepidermal water loss (TEWL), and the vascular response to hexyl nicotinate (HN) penetration as determined by laser-Doppler flowmetry, were measured in a group of 21 healthy volunteers. Each time profile of the vascular response to HN penetration was analysed using the following parameters: the baseline cutaneous blood flow, the lag-time between application and initial response (to), the time between application and maximum response (tmax.), the maximum response, and the slope of the curve. TEWL measured on the left volar forearm showed a normal range of 3.9–7.6 g/m2h and a small inter-individual variability [coefficient of variation (CV) 19–4%]. TEWL values at three other forearm sites did not show differences of clinical importance compared with the left volar forearm. The parameters of the vascular response to HN penetration spanned a wider normal range than the TEWL values (CV between 33 and 52%). Repeat measurements after a 1–2 month interval showed highly reproducible individual TEWL values. The mean difference between first and second measurements was only 0.03 g/m2h: the relative difference 0.6%. The intra-individual reproducibility of to and tmax for HN penetration was also high (relative differences of 2.8 and 3.1%, respectively). The other vascular response parameters were less reproducible (relative differences of 6.9–18.6%). We conclude that TEWL and selected parameters of HN penetration, as non-invasive tests of the stratum corneum barrier function, yield reproducible results and are hence useful for investigations assessing the skin barrier function in various disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2133.1993.tb15141.x
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  • 4
    Electronic Resource
    Electronic Resource
    Validation of an in vivo extraction method for human stratum corneum ceramides (1994)
    Springer
    Archives of dermatological research 286 (1994), S. 495-503 
    Details
    ISSN: 1432-069X
    Keywords: Stratum corneum lipids ; Transepidermal water loss ; Stripping ; Freeze-fracture electron microscopy ; Acetone/diethylether extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A topical acetone/diethylether (A/E) lipid extraction method was evaluated for its suitability for use in the study of stratum corneum lipids in various skin disorders. Its efficiency was compared in vitro with topical chloroform/methanol (C/M) extraction and with the classical ‘integral’ C/M extraction (submerged tissue) of stratum corneum or whole epidermis. To estimate the depth of lipid removal by A/E extraction, light microscopic and freeze-fracture electron microscopic studies were carried out on A/E and C/M topically treated skin samples. The in vivo experiments consisted of topical A/E extraction and of classical C/M extraction of scrapings of the stratum corneum. Transepidermal water loss (TEWL) was measured before and after topical A/E extraction and after every scraping procedure, and correlated with TEWL values found after stripping of the stratum corneum. The total amount of lipid found with both topical extraction procedures was lower than that found with the integral extraction of the stratum corneum. Light microscopy showed that topical C/M extraction induced cell damage in the living epidermal cell layers. Great interindividual variation in overall lipid composition was shown in the in vitro experiments irrespective of the extraction protocol used. However, the ceramide (CER) profiles in a single skin sample from the same subject were similar irrespective of the protocol used, and a uniformity in the CER profiles was found in skin samples from different subjects. Similar results were obtained with in vivo topical A/E extractions: marked interindividual variation was seen in overall lipid composition, but not in the CER profile. Furthermore, the CER profiles found using the A/E extraction procedure both in vivo and in vitro were similar. The CER profiles were also found to be identical throughout the stratum corneum, as revealed by scraping experiments. Since the CER profiles are though to play a major role in the stratum corneum barrier function, the non-invasive A/E extraction of epidermal lipids seems to be suitable for clinical application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371579
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    Paper (German National Licenses)
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