The British journal of dermatology
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Comparative Study
Intracellular expression of type VII collagen during wound healing in severe recessive dystrophic epidermolysis bullosa and normal human skin.
The ability of keratinocytes to synthesize basement membrane components in vivo during wound healing in normal human skin and in severe recessive dystrophic epidermolysis bullosa (RDEB) was investigated. Indirect immunofluorescence using anti-type VII collagen (VIIc, recognizing the globular non-helical component of the molecule), anti-type IV collagen, anti-laminin and bullous pemphigoid antisera, was performed on biopsies of intact skin and of healing skin taken between 7 and 14 days after dermatome injury (upper to mid-dermal wounding) in eight patients with severe RDEB and in seven normal subjects. Baseline anti-type VIIc immunofluorescence showed completely absent staining of the epidermis, dermis and dermo-epidermal junction in severe RDEB samples, and bright linear dermo-epidermal junction fluorescence in normal human skin. ⋯ In all the severe RDEB biopsies sampled between days 10 and 13 (5/5), anti-VIIc fluorescence was also seen with varying intensity within basal and lowermost suprabasal cells, and in one day 14 sample at the dermo-epidermal junction. Low levels of intracellular type IVc were seen in both groups, but only in those samples taken 7-9 days after injury; later biopsies showed only continuous dermo-epidermal junction staining. Linear basement membrane zone labelling with laminin and bullous pemphigoid antisera was seen in all samples in both sets of subjects, even at day 7, but there was no detectable intracellular antisera staining.(ABSTRACT TRUNCATED AT 250 WORDS)
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Letter Case Reports
Median nail dystrophy associated with isotretinoin therapy.
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Randomized Controlled Trial Comparative Study Clinical Trial
Taking the 'sting' out of local anaesthetics.
In order to investigate factors influencing the discomfort caused by the injection of different lignocaine preparations, a randomized, double-blind comparison of paired injections was performed in 32 patients. In all subjects 2% plain lignocaine was found to be more painful than 0.5% plain lignocaine. ⋯ The presence of sodium metabisulphite (the antioxidant in commercial adrenalized lignocaine) significantly increased the discomfort. Neutralization of acidic 0.5% lignocaine (pH 4.7) reduced the discomfort caused in 44% of patients, but this was not statistically significant.
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Tyrosinase is considered to be the rate-limiting enzyme for the biosynthesis of melanin in epidermal melanocytes, and thus tyrosinase activity is thought to be a major regulatory step in melanogenesis. To determine whether the rate of pigment production was controlled at the level of tyrosinase gene expression, we developed a culture system capable of generating large populations of pure human melanocytes and then measured both melanin content as determined spectrophotometrically by absorption at 475 nm and mRNA levels as detected by hybridization with cloned cDNA Pmel 34, encoding human tyrosinase. We examined the relationship between pigment content and tyrosinase mRNA levels among human melanoma and melanocyte lines with very different levels of basal pigmentation; between two clones of a single human melanoma line, one pigmented and one amelanotic; and sequentially in melanocytes before and after simulation with isobutylmethylxanthine to increase melanin content per cell. Using Northern blot analysis and in-situ hybridization we found no correlation between tyrosinase message levels and melanin content, suggesting that posttranscriptional regulation of tyrosinase and/or other events determine the rate of pigment synthesis in human melanocytes.
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The action spectrum for the induction of phototoxic erythema by treatment with 8-methoxypsoralen (8-MOP) and UVA peaks at around 335 nm. Because earlier investigations reported peak phototoxic activity at 365 nm, we compared the antipsoriatic efficacy of 335 and 365 nm in an oral psoralen photochemotherapy (PUVA) regimen using a monochromator. ⋯ However, 335 and 365 nm were equally effective if delivered in equal erythema doses. It appears that in human skin the antipsoriatic activity of 8-MOP parallels its erythemogenicity.