The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage and sunburn cell formation in human skin.

Background: alpha-Hydroxy acids (alphaHAs) are reported to reduce signs of aging in the skin and are widely used cosmetic ingredients. Several studies suggest that alphaHA can increase the sensitivity of skin to ultraviolet radiation. More recently, beta-hydroxy acids (betaHAs), or combinations of alphaHA and betaHA have also been incorporated into antiaging skin care products.

Histological effects of tazarotene 0.1% cream vs. vehicle on photodamaged skin: a 6-month, multicentre, double-blind, randomized, vehicle-controlled study in patients with photodamaged facial skin.

Background: Topical tazarotene has been shown to offer efficacy in ameliorating multiple effects of photodamage.

Objectives: To evaluate the histological effects of tazarotene cream on photodamaged skin.

Methods: In this multicentre, double-blind, randomized, vehicle-controlled study, 50 patients with photodamaged facial skin (at least mild fine wrinkling and mottled hyperpigmentation, with at least one of these being moderate) were randomized to apply tazarotene 0.

The polyhydroxy acid gluconolactone protects against ultraviolet radiation in an in vitro model of cutaneous photoaging.

Background: Ultraviolet (UV) radiation damages skin through a variety of mechanisms, including the generation of free radicals. Gluconolactone is a polyhydroxy acid (PHA) that is capable of chelating metals and may also function by scavenging free radicals, thereby protecting skin from some of the damaging effects of UV radiation.

Objective: This study measured the ability of gluconolactone to protect against UV radiation-induced damage.

Topical glycolic acid enhances photodamage by ultraviolet light.

Background: Alpha-hydroxy acids (AHAs) are widely used as ingredients in cosmetics. Several studies suggest that AHAs can increase the sensitivity of skin to ultraviolet (UV) light.

Purpose: This study was performed in order to determine whether short-term dermal treatment with glycolic acid, a representative AHA, can enhance the damaging effects of UV light.

Safety studies of topical imiquimod 5% cream on normal skin exposed to ultraviolet radiation.

Background: Imiquimod 5% topical cream is an immune response modifier that induces interferon alpha and interleukin-12, and exhibits antiviral and tumor-inhibiting properties. It is currently available for treatment of genital and perianal warts. Three randomized, open-label or assessor-blinded, placebo-controlled studies were carried out to assess its safety on normal white skin exposed to ultraviolet radiation (UVR).

The combination formulation of clindamycin 1% plus benzoyl peroxide 5% versus 3 different formulations of topical clindamycin alone in the reduction of Propionibacterium acnes. An in vivo comparative study.

Background: Isolates of Propionibacterium acnes resistant to one or more anti-acne antibiotics (most commonly erythromycin) are being increasingly reported, and the emergence of resistant strains can be associated with therapeutic failure of topical treatment.

Objective: Comparison of the in vivo effectiveness of the combination of clindamycin 1% plus benzoyl peroxide 5% in a gel formulation to that of each of 3 clindamycin 1% preparations (gel, lotion, and solution) with respect to reduction in counts of P. acnes cultured from the foreheads of healthy volunteers.

A pilot study to determine the effect of tazarotene gel 0.1% on steroid-induced epidermal atrophy.

Background: Repeated applications of a corticosteroid can induce epidermal atrophy. This study was performed to investigate whether the adjunctive use of tazarotene gel 0.1% might help to minimize the development of steroid-induced epidermal atrophy.

Photoreaction potential of orally administered levofloxacin in healthy subjects.

Objective: To evaluate the photoreaction potential of levofloxacin on exposure to solar-simulating radiation. Solar-simulating is ultraviolet (UV) light, defined as UVA in the 320-400 nm range and UVB in the 290-320 nm range.

Design: In a single-center, double-blind, randomized study, 30 adults (20 men, 10 women) received oral levofloxacin (500 mg qd x 5 d) or placebo.

Use of topical corticosteroid pretreatment to reduce the incidence and severity of skin reactions associated with testosterone transdermal therapy.

Local skin reactions at the application site are the most common adverse events associated with the testosterone transdermal delivery (TTD) systems used to treat postpubertal hypogonadism in males. This open-label, controlled pilot study was conducted to determine whether topical pretreatment with triamcinolone acetonide 0.1% cream might be useful in reducing the incidence and/or severity of chronic skin irritation when used in healthy volunteers receiving TTD systems.

The spectral dependence for UVA-induced cumulative damage in human skin.

The wavelength dependence for UVA-induced cumulative damage was investigated in human skin. Epidermal changes (stratum corneum thickening, viable epidermal thickening sunburn cell production), as well as dermal alterations (lysozyme deposition, inflammation), were used as indices of cumulative photoperturbation. UVA wavelengths between 320 nm and 345 nm were more effective than longer wavelengths (360-400 nm) in inducing viable epidermal thickening.

Quantitative assessment of cumulative damage from repetitive exposures to suberythemogenic doses of UVA in human skin.

Daily exposures to relatively small suberythemogenic fluences of UVA (50-200 kJ/m2) for 8 days resulted in cumulative morphological skin alterations indicative of early tissue injury. Histologically, irradiated skin revealed epidermal hyperplasia, inflammation and deposition of lysozyme along the dermal elastic fiber network. Sunburn cells were also present within the epidermis.

Cumulative effects from repeated exposures to suberythemal doses of UVB and UVA in human skin.

Background: The skin is repeatedly exposed to solar UV radiation. Long-term photodamage is a consequence of cumulative UV radiation injury. Hence an examination of the repetitive effects of UV exposure is more likely to yield clues to the early alterations that lead to photoaged skin than a single exposure.

An ultraviolet radiation action spectrum for immediate pigment darkening.

The wavelength dependence for immediate pigment darkening (IPD) was investigated by exposing the midback skin of volunteers to a series of incremental fluences of narrow waveband radiation isolated by band-pass filters in the 310-400 nm region. The threshold IPD fluence for each waveband was determined by visual assessment of the skin responses immediately after each exposure. The action spectrum, constructed from the mean threshold fluences, was broad and extended from 320 nm to 400 nm with a peak at around 340 nm.

Effects of topical ammonium lactate on cutaneous atrophy from a potent topical corticosteroid.

Background: Topical corticosteroids produce atrophic changes in skin, including thinning of the epidermis and decrease in dermal ground substance. We observed that 12% ammonium lactate produced an increase in the thickness of epidermis and increased amounts of dermal glycosaminoglycans.

Objective: Our purpose was to determine whether 12% ammonium lactate could minimize cutaneous atrophy produced by a potent topical corticosteroid.

Determination of UVA protection factors by means of immediate pigment darkening in normal skin.

A method is described for screening potentially useful photoprotective agents against UVA radiation by the use of immediate pigment darkening as an end point. Threshold doses of immediate pigment darkening showed a log normal distribution and the response was found to obey dose-reciprocity at irradiance levels below 50 mW/cm2. With this procedure, several marketed sunscreens containing benzophenone-3 as the only UVA absorber were found to have poor UVA protection factors, whereas those containing combinations of benzophenone-3 and butyl methoxydibenzoyl methane or melanin were more effective.

Reciprocity for solar simulators used in sunscreen testing.

Reciprocity for sunscreen solar protection factors (SPFs) and for delayed erythema was examined using a solar simulator equipped with neutral density filters to vary the beam intensity. Similar SPFs were obtained over a 15-fold intensity difference, using a sunscreen with a low (SPF-4) and a high (SPF-15) protection factor. Reciprocity was also observed for delayed erythema in unprotected skin.

Persistent light reactivity from systemic quinine.

A 41-year-old black female with psoriasis developed photosensitivity and a Koebner reaction while receiving phototherapy. She had been receiving oral quinine intermittently for muscle cramps. Photobiological evaluation revealed a strongly positive photopatch test to quinine sulfate and a marked persistent reduction in the minimal erythema dose to solar-simulated radiation in the uninvolved skin.

The photoprotective potential of the new superpotent sunscreens.

A sun protection factor (SPF)-15 and an SPF-30 sunscreen were compared with regard to their ability to prevent sunburn cell formation after the exposure of human skin to a standardized dose of solar-simulated radiation. The SPF-30 sunscreen provided a significantly superior degree of photoprotection and almost prevented sunburn cell induction. Because sunburn cells may be markers of ultraviolet radiation-induced damage to DNA, the new superpotent sunscreens should offer an advantage in the prevention of skin cancer and long-term actinic damage to skin.

Photosensitizing potential of certain nonsteroidal anti-inflammatory agents.

The nonsteroidal anti-inflammatory drugs (NSAIDs) have been repeatedly associated with photosensitivity reactions. The underlying mechanism however is not known, and the clinical features are not always consistent with either a phototoxic or a photoallergic mechanism. In this study, four NSAIDs were investigated for their phototoxicity potential in human volunteers using an oral dosing protocol.

Quantification of visible light-induced melanogenesis in human skin.

Exposure of normal skin to visible light (400-700 nm) resulted in the induction of immediate pigment darkening (IPD), immediate erythema and a persistent (delayed) tanning reaction. The intensity of pigmentation and time course of the reaction were monitored by measuring chromaticity coordinates. Both IPD and immediate erythema faded over a 24-h period but, unlike erythema, the pigmentation did not totally disappear and the residual tanning response remained unchanged for the rest of the 10-day observation period.

Wavelength dependence for DNA synthesis inhibition in hairless mouse epidermis.

Exposure of mammalian skin to ultraviolet radiation (UVR) results in a transient inhibition of scheduled DNA synthesis. The wavelength dependence for this response was investigated in the epidermis of albino hairless mice. Groups of animals were exposed to narrow wavebands of UVR (HPBW 6.

Comparison of sun protection factors obtained with a xenon solar simulator and an Ultravitalux lamp.

The influence of the type of UV source on the sun protection factor (SPF) was investigated in healthy volunteers with skin Types I to III. In an open-paired comparison, sunscreens with low, medium and high SPF were examined under identical test conditions using either a 150-watt xenon-arc solar simulator or a set of four 300-watt Osram Ultravitalux bulbs as the UV source. Despite wide differences in the spectral output of the two sources, both yielded similar mean SPF for each of the three test sunscreens.

Comparison of methods for assessing photoprotection against ultraviolet A in vivo.

Photoprotection against ultraviolet A (UVA) by three sunscreens was evaluated in humans, with erythema and pigmentation used as end points in normal skin and in skin sensitized with 8-methoxypsoralen and anthracene. The test sunscreens were Parsol 1789 (2%), Eusolex 8020 (2%), and oxybenzone (3%). UVA was obtained from two filtered xenon-arc sources.

An action spectrum for 8-methoxypsoralen-sensitized inhibition of DNA synthesis in vivo.

The wavelength dependence for 8-methoxypsoralen (8-MOP)-sensitized inhibition of scheduled DNA synthesis was investigated in the epidermis of albino hairless mice. Topical (0.1%) applications of 8-MOP followed by exposure to narrow bands from a monochromator in the range of 300-380 nm produced a dose-dependent inhibition of DNA synthesis.