Douglas B. Brown

Chronic sun exposure alters both the content and distribution of dermal glycosaminoglycans

Summary Chronic sun exposure leads to structural and functional alterations in exposed skin. Photoageing is a process distinct from the changes taking place due to chronological ageing. Unique alterations in the dermal extracellular matrix occur as a result of photoageing and are responsible for many of these physiological changes taking place in sun‐damaged skin. Accompanying the deposition of abnormal elastic tissue, or solar elastosis, are significant alterations in dermal glycosaminoglycans (GAGs). Accumulation of GAGs as a result of photoageing as demonstrated in both humans and animal models of photoageing seems almost paradoxical in view of the large amounts of GAGs present in the skin of newborns, making their skin well hydrated and supple, in sharp contrast to the weathered appearance of photoaged skin. We investigate the relative GAG content of photoaged skin using immunoperoxidase stains specific for hyaluronic acid and chondroitin sulphate, and determine the location of these GAGs using confocal laser scanning microscopy. Our results demonstrate significant increases in GAG staining in sun‐damaged vs. sun‐protected skin from the same individuals, as measured by computer‐based image analysis. Furthermore, confocal laser scanning microscopy reveals that the increased dermal GAGs in sun‐damaged skin are deposited on the elastotic material of the superficial dermis of photodamaged skin, and not between collagen and elastic fibres as in normal skin. The abnormal location of GAGs on these fibres may explain the apparent paradoxical weathered appearance of photodamaged skin despite increased GAGs.

Treatment of spider veins with the 595 nm pulsed-dye laser☆☆☆★

BACKGROUND Previous attempts to treat spider veins with the conventional 585 nm pulsed-dye laser with a 0.5-ms pulse duration have been relatively ineffective. Recently, a new pulsed-dye laser that is tunable from 585 to 600 nm with a pulse duration 3 times longer than previously available lasers has preliminarily been shown to be effective for treatment of spider veins. OBJECTIVE Our purpose was to evaluate the effectiveness of multiple treatments with the tunable long-pulse dye laser in treatment of spider veins of the lower extremity. METHODS Ten female volunteers were treated in two separate areas containing blue or red linear spider veins less than 1.5 mm in diameter. Treatments were administered with the pulsed-dye laser with a 1.5-ms pulse duration and 595-nm light at fluences of 15 and 20 J/cm2, and each subject received a total of 3 treatments at each site, administered at 6-week intervals. Photographs were taken before and 6 weeks after the last treatment. RESULTS Computer-based image analysis showed clearing of more than three fourths of veins after 3 treatments with 15 or 20 J/cm2. Side effects were minimal and the treatments were well tolerated. CONCLUSION The 595 nm, 1.5 ms pulse duration, pulsed-dye laser is safe and effective for treating blue or red spider veins of the lower extremities less than 1.5 mm in diameter in nontanned patients with Fitzpatrick skin types I and II. Multiple treatments improve on the results obtained after a single treatment.

Multicenter Study of the Safety and Efficacy of a 585 nm Pulsed‐Dye Laser for the Nonablative Treatment of Facial Rhytides

OBJECTIVE The objective of this study was to assess the safety and efficacy of a 585 nm flashlamp pulsed-dye laser for the nonablative treatment of facial rhytides. METHODS A multicenter prospective randomized controlled study on 58 volunteers was performed. A split-face approach was adopted, with one periorbital region acting as a control and the other receiving either one or two treatments. Patients were photographed and imaged three-dimensionally before and after treatment. Histologic sections were analyzed. RESULTS Three-dimensional topographic evaluation showed improvements of 9.8% (p= .0022) and 15% (p= .0029) in surface roughness for single and double treatments, respectively. Histology revealed an increase in type I collagen messenger ribonucleic acid expression, type III procollagen, chondroitin sulfate, and grenz zone thickness. Two treatments resulted in greater improvement than one treatment. CONCLUSION Clinical improvement was achieved following a single treatment. Further improvement was observed following a second treatment. The subjective evaluation of clinical improvement was consistent with both histologic and topographic quantitative measurements.

Common Fluorescent Sunlamps are an Inappropriate Substitute for Sunlight

Abstract Fluorescent sunlamps are commonly employed as convenient sources in photobiology experiments. The ability of Kodacel to filter photobiologically irrelevant UVC wavelengths has been described. Yet there still remains a major unaddressed issue—the over representation of UVB in the output. The shortest terrestrial solar wavelengths reaching the surface are ∼295 nm with the 295–320 nm range comprising ∼4% of the solar UV irradiance. In Kodacel-filtered sunlamps, 47% of the UV output falls in this range. Consequently, in studies designed to understand skin photobiology after solar exposure, the use of these unfiltered sunlamps may result in misleading, or even incorrect conclusions. To demonstrate the importance of using an accurate representation of the UV portion of sunlight, the ability of different ultraviolet radiation (UVR) sources to induce the expression of a reporter gene was assayed. Unfiltered fluorescent sunlamps (FS lamps) induce optimal chloramphenicol acetyltransferase (CAT) activity at apparently low doses (10–20 J/cm2). Filtering the FS lamps with Kodacel raised the delivered dose for optimal CAT activity to 50–60 mJ/cm2. With the more solar-like UVA-340 lamps somewhat lower levels of CAT activities were induced even though the apparent delivered doses were significantly greater than for either the FS or Kodacel-filtered sunlamp (KFS lamps). When DNA from parallel-treated cells was analyzed for photoproduct formation by a radioimmuneassay, it was shown that the induction of CAT activity correlated with the level of induced photoproduct formation regardless of the source employed.

Evaluation of sunscreens with various sun protection factors in a new transgenic mouse model of cutaneous photoaging that measures elastin promoter activation

BACKGROUND Long-term sun exposure can cause major alterations in the papillary dermis, resulting in the deposition of massive amounts of abnormal elastic material, termed solar elastosis. Previous work has demonstrated that this type of photodamage is accompanied by an increase in elastin and fibrillin messenger RNAs and elastin promoter activity. OBJECTIVE Our purpose was to develop a rapid and sensitive in vivo method for evaluating compounds offering protection against cutaneous photodamage. METHODS Using a line of transgenic mice that expresses the human elastin promoter linked to a chloramphenicol acetyltransferase reporter gene, we applied sunscreens with various sun protection factors to 5-day-old mice followed by 30 minimal erythema doses of solar simulating radiation for three consecutive days. RESULTS Solar simulating radiation alone resulted in a fivefold increase in elastin promoter activity. Sun protection factors of 2, 4, 8, and 15 yielded a reduction in promoter activity by 2.8%, 42.5%, 58.1%, and 70.3%, respectively. CONCLUSION These results confirm the use of this system as a rapid and sensitive in vivo model for evaluating compounds that protect against photodamage.

8-Methoxypsoralen and Ultraviolet A Radiation Activate the Human Elastin Promoter in Transgenic Mice: In vivo and in vitro Evidence for Gene Induction

Treatment of skin diseases with the combination of 8‐methoxypsoralen and ultraviolet A radiation (PUVA) results in clinical alterations in treated skin that resemble those observed in chronically photodamaged skin. The PUVA‐treated patients develop nonmelanoma skin cancers, pigmentary alterations and wrinkling characteristic of sun‐induced changes. The major alteration in the dermis of sun‐damaged skin is the deposition of abnormal elastic fibers, termed solar elastosis. Up‐regulation of elastin promoter activity in dermal fibroblasts explains the excess elastic tissue but not the reason for the aberrant morphology of the elastotic material. In order to study photoaging in an experimental system, we utilized a transgenic mouse line that expresses the human elastin promoter/chloramphenicol acetyltransferase construct in a tissue‐specific and developmentally regulated manner. Although UVB radiation has been demonstrated to increase promoter activity in vitro, UVA fails to demonstrate a similar effect at the doses utilized. In this study, we demonstrate the ability of PUVA treatment to up‐re‐gulate elastin promoter activity both in vitro and in vivo. These data help to explain the development of photoaging in sun‐protected PUVA‐treated skin. We attribute the up‐regulation of elastin promoter activity in response to PUVA to the formation of DNA photoadducts, which do not occur in response to UVA radiation alone.

The nitroxide Tempol affords protection against ultraviolet radiation in a transgenic murine fibroblast culture model of cutaneous photoaging

Abstract: The generation of reactive oxygen species is among the various mechanisms by which ultraviolet radiation damages skin. Tempol, a superoxide dismutase analogue which readily penetrates cell membranes when administered exogenously, has been shown to provide protection against some forms of oxygen‐dependent damage. In this study, we measured the ability of Tempol to protect against ultraviolet A‐ and ultraviolet B‐induced damage, using a previously described transgenic mouse model of cutaneous photoaging. The ability of Tempol to prevent ultraviolet radiation‐induced elastin promoter activation was determined in vitro. Tempol provided over 50% protection against ultraviolet B and over 70% protection against ultraviolet A as measured in our in vitro system. These results demonstrate the ability of the superoxide dismutase mimic, Tempol, to protect against ultraviolet induced elastin promoter activation. This compound could be a useful pharmacological agent to prevent cutaneous photoaging.

Ultraviolet-filtering properties of commonly used tissue cell culture plasticware.

Background: Fluorescent sunlamps are a common source of ultraviolet radiation (UVR) for photobiology research. However, these lamps emit a significant amount of biologically “irrelevant” wavelengths that, if not removed, can drastically skew results and perhaps lead to mistaken conclusions regarding human photobiology. The use of a cellulose triacetate sheet (Kodacel) to filter the shorter ultraviolet wavelengths has become the accepted standard in photobiology. Over time, the transmission characteristics of this sheet may be altered due to photochemical changes. In addition, in vitro experiments utilizing filtered fluorescent sunlamps require the removal of plastic tissue cell culture lids, increasing the possibility of contamination.