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Intact Skin (intact + skin)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

Determination of Wavelength-Specific UV Protection Factors of Sunscreens in Intact Skin by EPR Measurement of UV-Induced Reactive Melanin Radical

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007
Leslie Lund
ABSTRACT There remains an unmet need for skin tissue-based assays for the measurement of the UVA protection and efficacy of sunscreens. Here we describe development of a novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin. We have used areas of focal melanocytic hyperplasia in the skin of Monodelphis domestica to model the human nevus. We show that we are able to use this assay to determine the monochromatic protection factors (mPF) of research and commercial sunscreens at specific narrow wavebands of UVB, UVA and blue visible light. Both commercial sunscreens, a sun protection factor (SPF) 4 and an SPF 30 product, had mPFs in the UVB range that correlated well with their claimed SPF. However, their mPF in the UVA ranges were only about one-third of claimed SPF. This technique can be used to design and assay sunscreens with optimally balanced UVA and UVB protection. [source]

The effect of mechanical strain on protease production by keratinocytes

BRITISH JOURNAL OF DERMATOLOGY, Issue 2 2008
N. Bhadal
Summary Background, Intact skin is under constant tension, transmitted from the underlying dermis, but when tension is lost (i.e. upon wounding) protease activity is upregulated. Objectives, To investigate the effect of mechanical strain on protease production by both normal and transformed keratinocytes in vitro. Methods, Keratinocytes were seeded on to membranes precoated with either type I or type IV collagen. After 48 h medium was replaced with serum-free medium and mechanical strain was applied. Results, Mechanical strain resulted in decreased urokinase-type plasminogen activator (uPA) production by normal human keratinocytes (P < 0·05) but increased production by transformed keratinocytes (P < 0·05) cultured on type I and type IV collagen. Conclusions, Differential production of uPA by normal and transformed keratinocytes is relevant in the context of normal function, wound healing and tumorigenesis. [source]

Chlorhexidine anaphylaxis: case report and review of the literature

CONTACT DERMATITIS, Issue 3 2004
A. B. Krautheim
Chlorhexidine is a widely used antiseptic and disinfectant. Compared to its ubiquitous use in medical and non-medical environments, the sensitization rate seems to be low. Multivarious hypersensitivity reactions to the agent have been reported, including delayed hypersensitivity reactions such as contact dermatitis, fixed drug eruptions and photosensitivity reactions. An increasing number of immediate-type allergies such as contact urticaria, occupational asthma and anaphylactic shock have been reported. In the case report, we describe anaphylaxis due to topical skin application of chlorhexidine, confirmed by skin testing and sulfidoleukotriene stimulation test (CAST®: cellular antigen stimulation test). The potential risk of anaphylactic reactions due to the application of chlorhexidine is well known, especially that application to mucous membranes can cause anaphylactic reactions and was therefore discouraged. The use of chlorhexidine at a 0.05% concentration on wounds and intact skin was so far thought to be safe. Besides our patient, only one other case of severe anaphylactic reaction due to application of chlorhexidine on skin has been reported. Hypersensitivity to chlorhexidine is rare, but its potential to cause anaphylactic shock is probably underestimated. This review should remind all clinicians of an important potential risk of this widely used antiseptic. [source]

Straight-chain naltrexone ester prodrugs: Diffusion and concurrent esterase biotransformation in human skin

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2002
Audra L. Stinchcomb
Abstract Naltrexone (NTX) is an opioid antagonist used for treatment of narcotic dependence and alcoholism. Transdermal naltrexone delivery is desirable to help improve patient compliance. The purpose of this study was to increase the delivery rate of NTX across human skin by using lipophilic alkyl ester prodrugs. Straight-chain naltrexone-3-alkyl ester prodrugs of 2,7 carbons in chain length were synthesized and evaluated. In vitro human skin permeation rates were measured using a flow-through diffusion cell system. The melting points, solubilities, and skin disposition of the drugs were determined. The prodrugs were almost completely hydrolyzed on passing through the skin and appeared as NTX in the receiver compartment. The mean NTX flux from the prodrug-saturated solutions exceeded the flux of NTX base by ,2,7-fold. The amount of drug detected in the skin was significantly greater after treatment with the prodrug solutions compared with treatment with NTX base. The extent of parent drug (NTX) regeneration in the intact skin ranged from 28 to 91%. Higher NTX regeneration percentages in skin appeared to correlate with increased drug delivery rates. Definitively, the highly oil-soluble prodrugs provide a higher NTX flux across human skin in vitro and undergo significant metabolic conversion in the skin. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:2571,2578, 2002 [source]

Tetanus toxoid-loaded transfersomes for topical immunization

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2005
Prem N. Gupta
Topical immunization is a novel immunization strategy by which antigens and adjuvants are applied topically to intact skin to induce potent antibody and cell-mediated responses. Among various approaches for topical immunization, the vesicular approach is gaining wide attention. Proteineous antigen alone or in combination with conventional bioactive carriers could not penetrate through the intact skin. Hence, specially designed, deformable lipid vesicles called transfersomes were used in this study for the non-invasive delivery of tetanus toxoid (TT). Transfersomes were prepared and characterized for shape, size, entrapment efficiency and deformability index. Fluorescence microscopy was used to investigate the mechanism of vesicle penetration through the skin. The immune stimulating activity of these vesicles was studied by measuring the serum anti-tetanus toxoid IgG titre following topical immunization. The immune response was compared with the same dose of alum adsorbed tetanus toxoid (AATT) given intramuscularly, topically administered plain tetanus toxoid solution, and a physical mixture of tetanus toxoid and transfersomes again given topically. The results indicated that the optimal transfersomal formulation had a soya phosphatidylcholine and sodium deoxycholate ratio of 85:15%, w/w. This formulation showed maximum entrapment efficiency (87.34±3.81%) and deformability index (121.5±4.21). An in-vivo study revealed that topically administered tetanus toxoid-loaded transfersomes, after secondary immunization, elicited an immune response (anti-TT-IgG) comparable with that produced by intramuscular AATT. Fluorescence microscopy revealed the penetration of transfersomes through the skin to deliver the antigen to the immunocompetent Langerhans cells. [source]