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Biomedical subjects

J R McKinlay

Publications and source records attributed to J R McKinlay.

11 recordsLinked to original sources
PubMed2000

Nonablative skin remodeling: selective dermal heating with a mid-infrared laser and contact cooling combination.

BACKGROUND AND OBJECTIVE: Many of the microscopic changes associated with photodamage reside in the dermis. It follows that subsurface heating of the skin might allow for cosmetic enhancement without loss of the epidermis. Accordingly, we investigated the clinical and microscopic changes produced by a mid-infrared laser coupled with a contact cooling device. STUDY DESIGN/MATERIALS AND METHODS: Nine patients were treated with an erbium glass laser and sapphire cooling handpiece in contact with the skin. Postauricular sites were irradiated with pulse energies varying from 400-1,200 mJ and numbers of pulses from 4 to 40. Outcome measures included pain, edema, and erythema at predetermined postoperative intervals. Biopsies were performed just after treatment and 2 months postoperatively for selected pulse energy-pulse number combinations. RESULTS: Erythema, edema, and pain increased with pulse energy and number of pulses. Likewise, immediate epidermal necrosis and subsequent scarring were observed for larger pulse energy-pulse number combinations. At sites with epidermal preservation, on biopsy, immediate dermal thermal damage was observed in a band-like pattern. The deep boundaries of this band were dependent on pulse energy and pulse number. After 8 weeks, biopsies showed dermal fibroplasia roughly correlating to the band of immediate dermal thermal damage. CONCLUSION: Selective dermal heating can be achieved with a mid-infrared laser coupled to a contact surface cooling device. In this study, the range of fibroplasia and lack of clinically substantial cosmetic enhancement suggest that the dermal thermal damage achieved may be too deep and that the injury should be confined to more superficial levels to alter the most severely photodamaged dermis. Lasers Surg. Med. 26:186-195, 2000. Published 2000 Wiley-Liss, Inc.

Aged↗
PubMed2000

Comparison of carbon dioxide laser, erbium:YAG laser, dermabrasion, and dermatome: a study of thermal damage, wound contraction, and wound healing in a live pig model: implications for skin resurfacing.

BACKGROUND: Advances in laser technology allow for precise tissue removal and minimal thermal damage. However, mechanisms for cosmetic improvement have not been determined. Investigators have suggested that ablation, collagen shrinkage, and new collagen deposition all contribute to the clinical outcome. OBJECTIVE: In a live farm pig, we examined gross and microscopic effects of thermal and mechanical ablation devices to characterize immediate and long-term mechanisms in skin rejuvenation. METHODS: Two CO(2) lasers, an erbium:YAG laser, a dermabrader, and a dermatome were used to treat flank skin in a farm pig. There were 14 different treatment groups based on device type and working parameters. One to five sites were treated for each group. Wound surface areas were measured before treatment, immediately after treatment, and 7, 17, 23, 30, and 60 days thereafter. Biopsies were performed immediately after irradiation and 2, 7, 17, and 60 days after treatment. RESULTS: For the CO(2) laser-induced wounds, surface area measurements showed that immediate and final wound contraction tended to increase with initial residual thermal damage (RTD) for a range of values, above which immediate contraction remained relatively constant. Although there was no immediate wound contraction with mechanical ablation devices, long-term wound contraction in the dermatome and dermabrasion sites increased with depth of ablation. The erbium:YAG laser sites healed in a manner similar to that of mechanically induced wounds. Wound contraction profiles over time were dependent on depth of RTD and depth of ablation. Sixty days postoperatively, histologic examination showed varying degrees of fibroplasia. Overall, there was greater compaction and horizontal orientation of collagen fibers in those wounds with more than 70 microm of dermal RTD. Grossly, all wounds were similar after 60 days, with the exception of the deep dermabrasion sites, at which clinical scarring was observed. CONCLUSION: Our results show that CO(2) laser resurfacing produces short- and long-term wound contraction that is greater than that induced by purely ablative methods for the same total depth of injury. The erbium laser produced wound contraction profiles similar to those produced by mechanical wounding. The data suggest that initial collagen contraction and thermal damage modulate wound healing.

Animals↗
PubMed1999

Why does carbon dioxide resurfacing work? A review.

Despite the unquestionable efficacy of carbon dioxide laser skin resurfacing, mechanisms for cosmetic enhancement remain poorly characterized. Histological studies have provided some insight into the cascade of events from initial laser impact to final skin rejuvenation. However, there are few comprehensive studies of gross and microscopic wound healing. Additionally, the literature is fragmented; excellent individual articles appear in journals from widely disparate disciplines. For example, some reports relevant to laser skin resurfacing are "sequestered" in the engineering literature. This article is intended to update the physician on laser skin resurfacing based on the broadest review of the current literature. It proceeds from a discussion of initial laser-tissue interactions, such as collagen denaturation, to examination of long-term biological sequelae. At some cost to scientific rigor, mathematical models describing laser-tissue interactions are not presented.

Carbon Dioxide↗
PubMed1999

The clinical superiority of continuous exposure versus short-pulsed carbon dioxide laser exposures for the treatment of pearly penile papules.

Treatment of pearly penile papules was performed both with a conventional continuous-wave (CW) and a newer generation high energy pulsed carbon dioxide laser. When compared to the short pulsed laser, the CW laser, using relatively low power densities, provided superior hemostasis and improved visualization of the operative field. Despite the increase in thermal injury, wound healing was not compromised. The results of this case report support the CO2 laser in CW mode as the infrared laser treatment of choice for exophytic lesions with increased vascularity.

Adult↗
PubMed1998

Blue rubber bleb nevus syndrome.

Blue rubber bleb nevus syndrome is a rare autosomal dominant disorder of multiple venous malformations of the skin and gastrointestinal tract. The fragility of the gastrointestinal lesions may lead to significant occult blood loss and subsequent anemia.

Diagnosis, Differential↗