Differential Regulation of Tyrosinase Activity in Skin of White and Black Individuals In Vivo by Topical Retinoic Acid

Talwar, H. S.; Griffiths, Christopher E.M.; Fisher, Gary J.; Russman, Andrew; Krach, Kent; Benrazavi, S.; Voorhees, John J.

doi:10.1111/1523-1747.ep12476615

Cited by 39 publications

(26 citation statements)

References 33 publications

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“…In addition, it was shown that topical retinoic acid may be capable of modulating pigmentation in vivo, both positively and negatively, by increasing tyrosinase activity and production of keratinocyte-derived cytokines that stimulate melanogenesis in melanocytes with a low basal level of melanogenesis and little or no effect on the high basal level of melanogenesis in normal human melanocytes. 26,27 Pimecrolimus is a topical ascomycin-immunomodulating macrolactam that acts as a calcineurin inhibitor, affecting the activation of T cells and production of various cytokines. 28 This mechanism might interfere with the autoimmune destruction of melanocytes by activated T cells in vitiligo.…”

Section: Discussionmentioning

confidence: 99%

Repigmentation of Hypopigmented Scars Using an Erbium-Doped 1,550-nm Fractionated Laser and Topical Bimatoprost

Massaki

Fabi

Fitzpatrick

2012

Dermatologic Surgery

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Section: Discussionmentioning

confidence: 99%

Repigmentation of Hypopigmented Scars Using an Erbium-Doped 1,550-nm Fractionated Laser and Topical Bimatoprost

Massaki

Fabi

Fitzpatrick

2012

Dermatologic Surgery

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“…Melanin was extracted from postnatal eyes by homogenization and treatment in strong base as described (25). Relative net melanin content (per eye) was determined by spectrophotometric determination of absorbance at 462 nm and subtraction of the absorbance for albino retina.…”

Section: Methodsmentioning

confidence: 99%

Influence of Tyrosinase Levels on Pigment Accumulation in the Retinal Pigment Epithelium and on the Uncrossed Retinal Projection

Rachel

Mason

Beermann³

2002

Pigment Cell Research

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To study the relationship among tyrosinase activity, melanin production, and the routing of retinal ganglion cell (RGC) axons at the optic chiasm, we analysed mice with varying doses of the tyrosinase gene. These include the dark-eyed albino (Tyrc44H), a radiation-induced hypomorphic allele of tyrosinase; and transgenic mice carrying 1 or 2 alleles of a tyrosinase minigene on both wild-type (Tyr+) and albino (Tyrc) backgrounds. Melanization of the retinal pigment epithelium (RPE) occurred gradually even at <2% wild-type tyrosinase activity and was sensitive to tyrosinase activity up to <35% of wild-type levels, beyond which melanin synthesis appeared to be saturated. Overexpression of tyrosinase led to tyrosinase activity above wild type level, but did not increase melanin production. Although a loss of melanin because of a mutation in tyrosinase is associated with a decrease in the number of uncrossed fibers, elevating tyrosinase levels does not appear to cause an increase in the size of the uncrossed retinal projection. Our results suggest that replacing less than 35% of wild-type tyrosinase activity is sufficient to restore normal pigmentation of the RPE, and potentially, to allay visual defects.

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“…The enzyme tyrosinase is rate limiting in the production of melanin (3 1). Given the greater content of melanin in black skin, Talwar and coworkers studied basal and inducible levels of tyrosinase activity in black and Caucasian subjects (32). At baseline, the melanin content of black skin was approximately 3 X that of Caucasians.…”

Section: Racial Differences In Skin Structure and Physiologymentioning

confidence: 99%

Population differences in skin structure and physiology and the susceptibility to irritant and allergic contact dermatitis: implications for skin safety testing and risk assessment

Robinson

1999

Contact Dermatitis

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Skin safety testing and risk assessment utilize a comparative toxicological approach whereby the inherent toxicity (irritation or sensitization) is related to exposure to determine the potential risk to a consumer population. However, consumers cover a broad spectrum of individual characteristics in terms of skin types and functions, as well as their basic habits and practices in use of consumer products. Thus, we try to use very conservative estimates for both inherent susceptibility to the toxic effect as well as the potential worst‐case exposures. While the inherent variation can be considerable even within a country, it is magnified even further when products are marketed globally. Questions have arisen, therefore, as to whether a skin safety testing approach conducted locally or regionally can adequately predict for adverse effects for the global consumer. A good deal of speculation exists that population differences are real and should mandate population‐specific safety testing prior to marketing products in certain regions of the world. In an attempt to address this question, this review has summarized extensive literature covering basic skin biology and function and susceptibility to irritant and allergic skin responses. Throughout this literature, there are individual studies demonstrating population differences in skin properties or in the responsiveness to chemical insult. Some of the research on this topic has pointed fairly convincingly to a demonstrable population difference. The best example of this is the tendency for blacks to have a lesser skin reactivity than Caucasians, likely due to a more impenetrable barrier. In contrast, the comparative data for Caucasians and Asians, for males and females, and for different age clusters are far less compelling. In terms of tendencies, there are little data to support any real difference in skin barrier function or in skin irritation responsiveness between Caucasians and Asians or between males and females. Comparing different age profiles, there does appear to be a slight decline in reactivity to irritants among the elderly (> 65 years). Susceptibility to skin sensitization tends to be more related to exposure than any inherent susceptibility, though some data exist to suggest a slightly increased sensitivity in females versus males. On the basis of these data, standard procedures for skin safety testing and risk assessment can be considered relatively conservative. Most clinical skin safety studies are conducted in test populations that are comprised primarily of female Caucasians between the ages of 18 and 65 years. If anything, the skin reactivity “character” of this population cohort tends to skew toward the more reactive. This is not to say that population‐specific safety testing should not be done. There may be important reasons to pursue a population‐specific testing strategy in certain situations, perhaps due to regional, sex‐specific, or age‐specific marketing or to satisfy a regulatory or external relations need. However, there is yet no scienti...

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Differential Regulation of Tyrosinase Activity in Skin of White and Black Individuals In Vivo by Topical Retinoic Acid

Cited by 39 publications

References 33 publications

Repigmentation of Hypopigmented Scars Using an Erbium-Doped 1,550-nm Fractionated Laser and Topical Bimatoprost

Repigmentation of Hypopigmented Scars Using an Erbium-Doped 1,550-nm Fractionated Laser and Topical Bimatoprost

Influence of Tyrosinase Levels on Pigment Accumulation in the Retinal Pigment Epithelium and on the Uncrossed Retinal Projection

Population differences in skin structure and physiology and the susceptibility to irritant and allergic contact dermatitis: implications for skin safety testing and risk assessment

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