Ablation of human nail by pulsed lasers

BACKGROUND AND OBJECTIVE

The hard and resistant structure of the nail plate forms a natural barrier that limits the penetration of topical drugs. To overcome this barrier, the use of pulsed laser systems has been suggested. The purpose of this study was to evaluate the effect of four laser systems on nail plate ablation rates, ablation efficiencies, and subsequent craters morphology.

STUDY DESIGN/MATERIAL AND METHODS

Solid state Er:YAG (2.94 microns, 250 microseconds), a Ho:YSGG (2.08 microns, 250 microseconds), a XeC1 Excimer (308 nm, 15 ns), and a novel solid-state ultrashort pulse laser (1.05 microns, 350 fs) were used. Ablation rates, surface morphology, and extent of collateral damage were evaluated using light and electron microscopy.

RESULTS

Best ablation efficiencies were demonstrated with the ultrashort pulsed laser (1 micron/mJ), whereas maximum material removal per pulse was obtained with the Er:YAG laser (80 microns/ pulse). Scanning electron microscopy showed cracking damage with both Ho:YSGG and Er:YAG. XeC1 and the ultrashort pulse system left tissue surfaces free of cracks or thermal damage.

CONCLUSION

With its minimal acoustical and mechanical impact, high efficiency, and negligible collateral damage, the ultrashort pulse laser at 3 J/cm2 was found to be the optimal laser system for nail ablation.

Modulation of melanocyte intercellular adhesion molecule-1 by immune cytokines

Human melanocyte expression of intercellular adhesion molecule-1 (ICAM-1) with or without stimulation by interferon gamma (IFN-G), tumor necrosis factor alpha (TNF-alpha), or interleukin-1-alpha (IL-1 alpha), was measured utilizing direct immunofluorescence and fluorescence-activated cell sorting (FACS). Melanocytes grown in vitro expressed low levels of ICAM-1, which could be increased by exposing the cells to IFN-G, TNF-alpha, or IL-1 alpha. Each cytokine caused an enhancement of melanocyte ICAM-1 expression in a dose-dependent fashion. The lowest dose necessary to cause a significant increase in melanocyte ICAM-1 expression was 1 U/ml IFN-G, 0.3 ng/ml TNF-alpha, or 3 U/ml IL-1 alpha. Melanocytes were most sensitive to TNF-alpha stimulation, with the greatest levels of ICAM-1 expression following 30 ng/ml or more TNF-alpha. When IFN-G was added to melanocyte cultures in combination with TNF-alpha or IL-1 alpha, there was an additive increase in ICAM-1 expression but no synergy was noted with the combined cytokines. To our knowledge, this is the first report of melanocyte ICAM-1 induction by TNF-alpha and IL-1 alpha and by physiologically relevant doses of IFN-G. Because of the importance of ICAM-1 in the regulation of immune cell-target interactions, the study of ICAM-1 expression by melanocytes may help us to better understand immune mechanisms of melanocyte injury.