Response of pigmented porcine skin ( Sus scrofa domestica ) to single 3.8-micron laser radiation pulses

Abstract

Background and purpose:The purpose of this study is to determine the impact of melanin on skin response to single 3.8 micron, eight microsecond laser pulses and the difference in lesion formation thresholds for input into laser safety standards. Williams et al., performed a study examining laser tissue interaction from 3.8-micron lasers in lightly pigmented Yorkshire pigs (Sus scrofa domestica). 1 However, studies performed by Eggleston et al comparing pigmented and lightly pigmented skin with human skin found that the Yucatan mini-pig is a superior model for laser skin exposures. 2 Methods: Five Yucatan mini-pigs under general anesthesia were exposed to 3.8 micron laser pulses ranging from 0.8 J/cm 2 to 93 J/cm 2 . Gross examinations were done acutely and 24 hours after laser exposure. Skin biopsies were then collected at various times post exposure, and histologic examinations were conducted. Results: The 24 hour ED 50 was determined to be 4.5 J/cm 2 with fiducial limits of 6.2 and 2.2 J/cm 2 . As deposited energy was increased, the lesion presentation ranged from whitening of the epidermis (4 J/cm 2 ) to whitening with inflammatory centers (14 J/cm 2 ), and at the highest energy levels inflammatory areas were replaced with an epidermal ulcerated central area (>21 J/cm 2 ). Conclusion: Preliminary findings suggest pigmentation or melanin may play a minor role in the mechanism of laser-tissue damage. The ED 50 of Yorkshire pigs was 2.6 J/cm 2 . 3 The ED 50 of the Yucatan mini-pig was found to be 3.6 J/cm 2 , and although it was higher, it is still within the 95% fiducial limits.

Use of Miniature Pig for Biomedical Research, with Reference to Toxicologic Studies

“…On the basis of epidermal skin thickness measurements and melanin assessment, the flank and dorsal neck of the Yucatan minipigs were closely comparable to those of the human epidermis from the face, neck and arms, and better suited to laser injury studies than the Yorkshire pig models of the human skin because of their higher pigmentation levels 44,46 . In a later study, however, no statistical difference was found between the 24 h effective dose of laser pulses in two breeds, Yorkshire pigs and Yucatan minipigs, nor were there any differences in histologic lesions represented by desiccation of the superficial layer of epidermis to desiccation with inflammatory centers, and finally replacement of inflammatory centers with areas of epidermal ulceration 47 .…”

Abdominal Wall Reconstruction after Flap Surgery and the Effect on the Immune System

“…This study highlights the new flap techniques used to repair the abdominal wall defect and provides readers with a better understanding on the postoperative course, the flaps histology, and the immune consequences. The pigs have been utilized in numerous studies of tissue healing and blood flow since they mimic human cutaneous and vascular anatomy [ 9 – 12 ]. The animal models offer important advantages for plastic repair progress.…”

Cutaneous sensation threshold for 3.8 μm radiation from a short duration pulsed laser on the calves of human subjects: A pilot study

“…1 The sensation threshold is at least two orders of magnitude greater than the MPE. 17,18 Ordinarily the MPE is set a factor of ten below the threshold for gross skin changes, so that a MPE of 2.5ϫ 10 −1 J/cm 2 would be indicated. It is of note that changes to the skin were limited and did not appear to have any long term consequences.…”