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At least 487 records · Page 27Linked to original sources
PubMed2000

Evaluation of a human bio-engineered skin equivalent for drug permeation studies.

PURPOSE: To test the barrier function of a bio-engineered human skin (BHS) using three model drugs (caffeine, hydrocortisone, and tamoxifen) in vitro. To investigate the lipid composition and microscopic structure of the BHS. METHODS: The human skin substitute was composed of both epidermal and dermal layers, the latter having a bovine collagen matrix. The permeability of the BHS to three model drugs was compared to that obtained in other percutaneous testing models (human cadaver skin, hairless mouse skin, and EpiDerm). Lipid analysis of the BHS was performed by high performance thin layered chromatography. Histological evaluation of the BHS was performed using routine H&E staining. RESULTS: The BHS mimicked human skin in terms of lipid composition, gross ultrastructure, and the formation of a stratum corneum. However, the permeability of the BHS to caffeine, hydrocortisone, and tamoxifen was 3-4 fold higher than that of human cadaver skin. CONCLUSIONS: In summary, the results indicate that the BHS may be an acceptable in vitro model for drug permeability testing.

Animals↗
PubMed2002

Efficacy of stratum corneum lipid supplementation on human skin.

Recent studies suggest that supplementing intercellular lipids of the stratum corneum in ageing populations or in people with dry skin can stimulate the functioning of the skin. This work lends support to the reinforcement capacity of two different stratum corneum lipid mixtures (synthetic stratum corneum lipid mixtures, SSCL, and internal wool lipid extracts, IWL) formulated as liposomes on healthy skin of two differently aged groups of individuals. Protection of healthy skin against detergent-induced dermatitis was evaluated. Transepidermal water loss and capacitance were used to evaluate the effect of these formulations in in vivo long-term studies. Increase in water-holding capacity is obtained only when the formulations applied are structured as liposomes. This is slightly more pronounced for aged skin. Subsequent SLS exposure reflected the protection of healthy human skin against detergent-induced dermatitis. Slightly better results were obtained with IWL containing a mixture of natural ceramides than with SSCL with only one ceramide present in the formulation. All these results support the beneficial effects of skin lipid supplementation given their resemblance to the lipids in the stratum corneum both in composition and in the structuring of the formulation.

Adult↗
PubMed2000

Photoscratch testing in systemic drug-induced photosensitivity.

Because of numerous false-negative results, photopatch testing is seldom relevant in systemic drug-induced photosensitivity. These false-negative photopatch test results can be attributed to the inability of the drug to penetrate into the epidermis. In order to enhance the penetration of the tested drug into the epidermis, some authors proposed to breach the cutaneous barrier. We performed a prospective study comparing photopatch and photoscratch testing. Fifteen patients presenting with a systemic drug-induced photosensitivity, proved by a favourable outcome after discontinuing the drug, were tested. For each drug, photopatch and photoscratch tests were performed. Two-thirds of the patients had negative photopatch and photoscratch tests with the suspected drugs. Photopatch and photoscratch tests were positive and relevant, respectively, in 3 and 4 patients. Photoscratch tests induced more false-positive results due to irritation confirmed on control subjects. Our study proves that photoscratch tests do not change the sensitivity of phototesting.

Adult↗
PubMed2003

Enabling topical immunization via microporation: a novel method for pain-free and needle-free delivery of adenovirus-based vaccines.

The skin represents an excellent site for vaccine inoculation due to its natural role as a first line of contact with foreign pathogens and the high local frequency of antigen presenting cells. To facilitate skin-directed immunization, a new technique has been developed (termed microporation) whereby a vaporization process is used to remove tiny areas of the stratum corneum creating microscopic pores that allow access to the underlying viable epidermis. Reporter gene expression was 100-fold increased following application of an adenovirus vector to microporated skin when compared to intact skin. Furthermore, 10-100-fold greater cellular and humoral immune responses were observed following topical administration of an adenovirus vaccine to microporated skin versus intact skin. Hairless mice responded to the microporated adenovirus vaccine equivalently to mice with normal hair follicle distribution demonstrating the activity of the microporated vaccine was not related to follicle count. In a tumor challenge model using a surrogate antigen, microporation increased vaccine efficacy by approximately 100-fold compared to intact skin. Finally, microporation enabled delivery of an adenovirus vaccine carrying a relevant melanoma antigen resulting in the development of auto-immune vitiligo and tumor protection. Thus, the microporation technology has proven to be a reliable and easy method to enable skin-directed vaccination.

Adenoviridae↗
PubMed2006

Gene therapy progress and prospects: the skin--easily accessible, but still far away.

Significant progress has been made in corrective gene therapy of inherited skin diseases. This includes advances in vector technology, targeted gene expression, gene replacement, and the availability of appropriate animal models for a variety of candidate diseases. In addition, an increased understanding of the uptake and trafficking mechanisms inside keratinocytes has evolved. Topical application facilitates DNA vaccination through the skin, albeit clinical benefits have not yet materialized. However, the translation into clinical trials has only been partially mastered. The latter and the control of immune responses represent challenges for the research community.

Animals↗
PubMed2000

Barrier recovery rate varies time-dependently in human skin.

The recovery in cutaneous barrier functions, assessed in terms of transepidermal water loss, 1 h after tape stripping of volar forearm skin in human volunteers, was investigated at different times over the 24 h day. The barrier recovery rate was significantly lower between 20:00 h and 23:00 h than that at other time points. The skin surface temperature and the basal transepidermal water loss reached their highest values at about 03:00 h (33.6 degrees C and 0.30 mg cm-2 h-1), while the cortisol level in the saliva was highest at 09:00 h (7.8 pmol mL-1). These results suggest significant time-dependent variation in cutaneous barrier repair independent of changes in skin temperature and cortisol level.

Adult↗
PubMed2000

Fluorescence excitation spectroscopy provides information about human skin in vivo.

Fluorescence spectroscopy of human skin has the potential to provide useful morphologic and biochemical information. The endogenous fluorescence of human skin has been investigated in vivo on normal human volunteers as well as on patients with psoriasis and it was found that characteristic bands can be identified in the fluorescence spectra that are associated with specific skin fluorophores. One epidermal band (295 nm excitation, attributed to tryptophan) and two dermal bands (335 and 370 nm excitation, attributed to collagen cross-links) were consistently present in all fluorescence spectra. In addition, the fluorescence spectra obtained from lesions and nonlesional sites of psoriatic patients differed from those obtained from healthy volunteers and the hyperproliferative state of the lesions was characterized by a significantly larger signal at 295 nm excitation. These results indicate that fluorescence spectroscopy is a promising technique for the investigation of human skin in vivo.

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

Direct comparison of skin physiology in children and adults with bioengineering methods.

The aim of the study was to investigate whether the physiologic skin parameters of transepidermal water loss (TEWL), stratum corneum hydration (capacitance and conductance), dynamic stratum corneum hydration parameters (hygroscopicity and water-holding capacity), skin color (a* and L* axes; chromameter), cutaneous blood perfusion [laser Doppler flowmetry (LDF)], and pH value differ between a sample of 44 children [C] (average age 3.5 years) and a directly comparable sample of 44 adults (their parents) [P] (average age 34.6 years). The results can be described as follows: TEWL C: 6.2 g/m2/h, P: 5.4 g/m2/h; stratum corneum hydration, capacitance C: 75.4 AU, P: 76.1 AU; conductance C: 27.1 microS, P: 19.2 microS; hygroscopicity C: 129.0 AU, P: 132.7 AU; water-holding capacity: C: 127.7 AU, P: 127.6 AU; redness (a*) C: 7.31, P: 8.21; lightness (L*) C: 67.63, P: 66.36; LDF (%) C: 24.6, P: 18.7; pH value C: 4.91, P: 5.07. In comparison to the skin of the adult sample we investigated (the parents of the 44 children), the skin of the small child can be characterized in the following way: it has a significantly lower hygroscopicity, a lighter (higher L* values) and less red color (lower a* values), and an increased cutaneous blood perfusion (LDF).

Adult↗
PubMed2000

The use of aromatherapy in intrapartum midwifery practice an observational study.

The authors report the process and results of an evaluation of a midwifery aromatherapy service for mothers in labour: This study of 8058 mothers in childbirth, is the largest research initiative in the use of aromatherapy within a health-care setting. The study involved a wide range of participants, from mothers who experienced a low risk, spontaneous labour and birth, to those whose labour was induced, and those who had vaginal operative delivery and Caesarean section. The study-took place over a period of 8 years, which enabled a more challenging test of the effect of aromatherapy on intrapartum midwifery practice and outcomes. In the study a total of 10 essential oils were used, plus a carrier oil, which were administered to the participants via skin absorption and inhalation. The study found little direct evidence that the practice of aromatherapy per se reduces the need for pain relief during labour, or the incidence of operative delivery. But a key finding of this study suggests that two essential oils, clary sage and chamomile are effective in alleviating pain. The evidence from this study suggests that aromatherapy can be effective in reducing maternal anxiety, fear and/or pain during labour. The use of aromatherapy appeared to facilitate a further reduction in the use of systemic opioids in the study centre, from 6% in 1990 to 0.4% in 1997 (per woman). Aromatherapy is an inexpensive care option. In 1997 when 1592 mothers used aromatherapy, the total cost was 769.17 Pounds. The study reports a minimal incidence of associated symptoms. Out of 8058 mothers, 1% (100) recorded an associated symptom. These were mild in nature. The successful model of integrated practice that this aromatherapy study presents, offers a useful example for other units to consider.

Adult↗