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Skin Pigmentation (skin + pigmentation)

Distribution by Scientific Domains

Medical Sciences	56%
Life Sciences	38%

Selected Abstracts

A Case,Sibling Assessment of the Association Between Skin Pigmentation and Other Vitamin D-related Factors and Type 1 Diabetes Mellitus

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2009
Anne-Louise Ponsonby
Fair skin pigmentation has been associated with a higher risk of type 1 diabetes mellitus (T1DM). The aim is to compare children with T1DM directly to a sibling in relation to their skin pigmentation in sun-exposed and unexposed sites, past sun exposure and methylation of the VDR gene promoter. The sample consisted of children with T1DM attending a diabetes outpatient clinic and siblings (total n = 42). Cutaneous melanin density was estimated using a spectrophotometer. Parental report on past sun exposure was obtained. DNA methylation analysis of the VDR gene promoter was conducted. Matched data analysis was performed comparing each case directly to their sibling. Cases were significantly more likely to have lighter skin pigmentation at the upper arm (AOR 0.69 [95% CI: 0.52, 0.90]; P = 0.01). Low infant sun exposure was imprecisely associated with a two-fold increase in T1DM risk (AOR 2.43 [95% CI: 0.91, 6.51]; P = 0.08 for under 1 h of winter sun exposure per leisure day). The VDR gene promoter was completely unmethylated in both cases and siblings. The previously demonstrated association between light skin pigmentation and T1DM risk was evident even in this comparison across sibling pairs. Further work on past UVR exposure and related factors such as skin pigmentation is required. [source]

Ethnic Dermatology: Clinical Problems and Skin Pigmentation

AUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 2 2010
Sam Kalouche
No abstract is available for this article. [source]

Antimelanogenesis effect of Tunisian herb Thymelaea hirsuta extract on B16 murine melanoma cells

EXPERIMENTAL DERMATOLOGY, Issue 12 2007
Mitsuko Kawano
Abstract:, Skin pigmentation is the result of melanogenesis that occurs in melanocytes and/or melanoma cells. Although melanogenesis is necessary for the prevention of DNA damage and cancer caused by UV irradiation, excessive accumulation of melanin can also cause melanoma. Thus, we focused on the antimelanogenesis effect of an extract from Thymelaea hirsuta, a Tunisian herb. Murine melanoma B16 cells were treated with T. hirsuta extract, and then cell viability and synthesized melanin content were measured. We found that the T. hirsuta extract decreased the synthesized melanin content in B16 cells without cytotoxicity. Tyrosinase is a key enzyme of melanogenesis and extracellular signal-regulated kinase (ERK)-1/2 phosphorylation is known to be related to melanogenesis inhibition. To clarify its mechanism, we also determined ERK1/2 phosphorylation and tyrosinase expression level. ERK1/2 was immediately phosphorylated in cells just after treatment with the extract. The tyrosinase expression was inhibited after 24 h of stimulation with the extract. The T. hirsuta extract was fractionated, and we found that one fraction considerably decreased the melanin synthesis in B16 cells and that this fraction contains daphnanes as the main component. This indicates that our findings might be attributable to daphnanes. [source]

Effective inhibition of melanosome transfer to keratinocytes by lectins and niacinamide is reversible

EXPERIMENTAL DERMATOLOGY, Issue 7 2005
Amanda Greatens
Abstract:, Skin pigmentation results in part from the transfer of melanized melanosomes synthesized by melanocytes to neighboring keratinocytes. Plasma membrane lectins and their glycoconjugates expressed by these epidermal cells are critical molecules involved in this transfer process. In addition, the derivative of vitamin B3, niacinamide, can inhibit melanosome transfer and induce skin lightening. We investigated the effects of these molecules on the viability of melanocytes and keratinocytes and on the reversibility of melanosome-transfer inhibition induced by these agents using an in vitro melanocyte,keratinocyte coculture model system. While lectins and neoglycoproteins could induce apoptosis in a dose-dependent manner to melanocytes or keratinocytes in monoculture, similar dosages of the lectins, as opposed to neoglycoproteins, did not induce apoptosis to either cell type when treated in coculture. The dosages of lectins and niacinamide not affecting cell viability produced an inhibitory effect on melanosome transfer, when used either alone or together in cocultures of melanocytes,keratinocytes. Cocultures treated with lectins or niacinamide resumed normal melanosome transfer in 3 days after removal of the inhibitor, while cocultures treated with a combination of lectins and niacinamide demonstrated a lag in this recovery. Subsequently, we assessed the effect of niacinamide on facial hyperpigmented spots using a vehicle-controlled, split-faced design human clinical trial. Topical application of niacinamide resulted in a dose-dependent and reversible reduction in hyperpigmented lesions. These results suggest that lectins and niacinamide at concentrations that do not affect cell viability are reversible inhibitors of melanosome transfer. [source]

P43 Acute urticaria to infliximab

CONTACT DERMATITIS, Issue 3 2004
Ana Giménez-Arnau
Infliximab is a chimeric antitumor necrosis factor-alpha monoclonal antibody used to treat Crohn's disease and rheumatoid arthritis. Acute infusion reactions, headache, fever, chills, urticaria and chest pain were seen in 17% of patients with infliximab compared with 7% of those receiving placebo. Other adverse cutaneous reactions are fungal dermatitis, eczema, seborrhoea, hordeolum, bullous eruption, furunculosis, periorbital oedema, hyperkeratosis, rosacea, verruca, skin pigmentation, alopecia, leukocytoclastic vasculitis, lichenoid drug eruption, erythema multiforme, perniosis-like eruption, granuloma annulare and acute folliculitis. Any pathogenic mechanism has been suggested. Patch test with infliximab can induce flare-up of lesions, nausea and malaise and suggest a percutaneous absortion. A sixty years-old man with atopy background and rheumatoid arthritis treated with Remicare®, infliximab who developed a severe acute urticaria with angioedema is presented. The lesions appearance after previous endovenous administrations and the worsening spreading wheals days after the injection clinically suggested an hypersensitivity mechanism. The protocolized study drug hypersensitivity performed showed only the Prick Test positivity with infliximab at 30/60 minutes. Patch test with infliximab was negative and any adverse event was reported. Actually the patient is treated with etanercept and this drug is well tolerated. This result suggested a type I hypersensitivity mediated reaction. Urticaria could be induced as immunologic reaction of the host against the murine part of infliximab, just as it hapens with other antichimeric antibodies. [source]

Fractional Photothermolysis for Photoaging of Hands

DERMATOLOGIC SURGERY, Issue 1 2008
MING H. JIH MD
BACKGROUND Laser treatment for photoaging of the hands should ideally address pigmentary alteration as well as associated skin roughness and wrinkling. Fractional resurfacing has been previously shown to effectively treat facial rhytids and dyschromia. OBJECTIVE We examined the effect of fractional resurfacing for photoaging of the hands. METHODS AND MATERIALS Ten patients (skin phototypes II to IV) with hand photodamage were randomized to receive five treatments with a 1,550-nm diode-pumped erbium fiber laser (Fraxel SR, Reliant Technologies) laser on either the right or left hand. Treatments were performed at settings of 8 to 9 mJ/microscopic treatment zone and density of 2,500 microscopic treatment zones/cm2. Subjective assessments by the patients and investigator were performed for skin roughness, wrinkling, and pigmentation using a 5-point scale. Skin biopsies were taken at baseline and at 1 and 3 months. RESULTS Patient subjective assessment and physician clinical assessment at 1 and 3 months revealed a mean 51% to 75% improvement in skin pigmentation and 25% to 50% improvement in skin roughness and wrinkling. Biopsies of the skin showed increased density of dermal collagen. Patients experienced transient erythema and edema and none had scarring or other adverse effects. LIMITATIONS This was a small study. CONCLUSION Fractional resurfacing appears to be an effective and safe treatment modality for correcting both the pigmentary and the textural aspects of photoaging of the hand. [source]

Skin lightening preparations and the hydroquinone controversy

DERMATOLOGIC THERAPY, Issue 5 2007
Zoe Diana Draelos
ABSTRACT:, Skin lightening preparations are widely used in dermatology by persons of all Fitzpatrick skin types. Fitzpatrick skin types I,III require local pigment lightening for the treatment of hormonally induced melasma and postinflammatory hyperpigmentation caused by acne and trauma. Fitzpatrick skin types IV and darker have an even greater need for skin lightening for social reasons, as well as pigmentary changes that occur around the eyes, in the intertriginous areas, following dermatitis, or with acne and trauma. The gold standard dermatologic agent for skin lightening was hydroquinone, until regulatory agencies in Japan, Europe, and most recently in the United States questioned the safety of this substance. This has encouraged research into alternative agents to inhibit skin pigmentation such as retinoids, mequinol, azelaic acid, arbutin, kojic acid, aleosin, licorice extract, ascorbic acid, soy proteins, and N-acetyl glucosamine. The efficacy and safety of each of these ingredients is examined as possible topical alternatives to hydroquinone. [source]

A study of a single variant allele (rs1426654) of the pigmentation-related gene SLC24A5 in Greek subjects

EXPERIMENTAL DERMATOLOGY, Issue 2 2009
Gerasimos Dimisianos
Abstract:, The SLC24A5 gene, the human orthologue of the zebrafish golden gene, has been shown to play a key role in human pigmentation. In this study, we investigate the prevalence of the variant allele rs1426654 in a selected sample of Greek subjects. Allele-specific polymerase chain reaction was performed in peripheral blood samples from 158 attendants of a dermatology outpatient service. The results were correlated with pigmentary traits and MC1R genotype. The vast majority of subjects (99%) were homozygous for the Thr111 allele. Only two subjects from the control group (1.26%) were heterozygous for the alanine and threonine allele. Both of these Thr111/Ala111 heterozygotes carried a single polymorphism of MC1R (one with the V92M variant and another with the V60L variant). Following reports of the rs1426654 polymorphism reaching fixation in the European population, our study of Greek subjects showed a prevalence of the Thr111 allele, even among subjects with darker skin pigmentation or phototype. [source]

Regulation of MC1R signalling by G-protein-coupled receptor kinases

EXPERIMENTAL DERMATOLOGY, Issue 9 2004
J. C. García-Borrón
The melanocortin 1 receptor (MC1R) is a key regulator of melanocyte proliferation and differentiation and a major determinant of human skin phototype and skin cancer risk. Although the regulation of MC1R gene expression is fairly well understood, little is known about regulatory mechanisms acting at the protein level. In particular, no information is available on homologous desensitization of MC1R signalling. We studied MC1R and Mc1r desensitization and found that: 1) MC1R and Mc1r in melanoma cells undergo homologous desensitization, demonstrated by decreases in cAMP contents upon continuous exposure to agonists, 2) desensitization is not dependent on PKA, PKC, calcium mobilization or MAPKs but is agonist dose dependent, suggesting a role of receptor occupancy, 3) melanoma cells express two members of the GRK family of serine/threonine kinases, GRK2 and GRK6, 4. These kinases are expressed in normal melanocytes, 5) in cotransfection experiments performed with HEK 293T cells, GRK2 strongly impairs agonist-dependent signalling by MC1R or Mc1r, 6) expression of a dominant negative GRK2 mutant in melanoma cells increases their cAMP response to MC1R agonists, 7) cotransfection of HEK 293T cells with GRK6 and MC1R inhibits both basal and agonist-dependent signalling, and 8) cAMP production in agonist-stimulated melanoma cells is strongly impaired by enrichment with GRK6 following stable transfection. Therefore, GRK2 and GRK6 are key regulators of MC1R signalling and may be important determinants of normal and pathological skin pigmentation. [source]

,-MSH and cAMP signalling in normal human melanocytes

EXPERIMENTAL DERMATOLOGY, Issue 9 2004
R. Buscà
Melanocytes are neural crest-derived skin cells specialized in the synthesis of melanin pigments responsible, in human, for skin and hair colour. The pro-opiomelanocortin peptide, ,-MSH is a strong melanogenic agent secreted by keratinocytes following UV radiation. ,-MSH through the binding to the MC1R and activation of the cyclic AMP pathway plays a pivotal role in melanocyte differentiation and in the regulation of skin pigmentation. During the last few years, we have elucidated the molecular events linking the cAMP pathway to melanogenesis upregulation. This cascade involves the activation of protein kinase A and CREB transcription factor, leading to the upregulation of the expression of microphthalmia-associated transcription factor (MITF). MITF binds and activates the melanogenic gene promoters thereby increasing their expression, which results in an increased melanin synthesis. Beyond this simplified scheme, other intracellular signalling pathways are regulated by cAMP and participate to the regulation of melanocyte differentiation. Indeed, cAMP inhibits the phosphatidyl inositol 3-kinase pathway, leading to the inhibition of AKT and to the activation of GSK3,. This kinase phosphorylates MITF and allows its binding to the target sequence. Such pathways are involved in the upregulation of melanogenesis. ,-MSH and cAMP signalling also regulate melanocyte dendricity, and melanosome transport through the inhibition of the Rho GTPase cascade that function downstream the PI3 kinase. It should be also mentioned that cAMP activates the ERK pathway through a melanocyte-specific pathway involving Ras and B-Raf. The activation of ERK and RSK1 leads to the phosphorylation of MITF and target MITF to the proteasome degradation pathway. Interestingly, several proteins involved in melanocyte differentiation by ,-MSH (MC1R, PI3K, B-Raf and MITF) have also been implicated in the development of melanoma, suggesting that the cAMP pathway could influence melanocyte transformation. [source]

Vitamin D deficiency in a multinational refugee population

INTERNAL MEDICINE JOURNAL, Issue 12 2007
H. D. Wishart
Abstract Background: Populations with increased skin pigmentation who have migrated to countries of high latitude are at increased risk of low vitamin D. This study aimed to determine the prevalence of low vitamin D among the refugee population arriving in New Zealand. Methods: An audit of all refugees arriving at the national refugee resettlement centre from May 2004 to May 2005 was carried out. Serum 25-hydroxyvitamin D3 levels were measured and defined as normal (50,150 nmol/L) or low, with low subdivided into insufficient (25 to <50 nmol/L) and deficient (<25 nmol/L). Whether vitamin D status varied with age and sex was determined. Results: Vitamin D was measured in 869 (99%) of the refugees and was low in 470 (54%, 95% confidence interval (CI) 51,57%). It was insufficient in 323 (37%, 95%CI 34,41%) and deficient in 147 (17%, 95%CI 15,20%). Female sex was associated with at least a 10 times increased risk of vitamin D deficiency (relative ratio 13.93, 95%CI 10.15,17.96). Women aged between 17 and 45 years and men aged 46 years and more were at greatest risk. Conclusion: Poor vitamin D status is prevalent among refugees arriving in New Zealand. Women, particularly those of child-bearing age are at greatest risk. Screening and ongoing surveillance for vitamin D deficiency should be considered for all recent refugee immigrants to New Zealand. [source]

A review of ageing and an examination of clinical methods in the assessment of ageing skin.

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2008
Part 2: Clinical perspectives, clinical methods in the evaluation of ageing skin
Synopsis With the advancement of skin research, today's consumer has increased access to technological information about ageing skin and hair care products. As a result, there is a rapidly increasing demand for proof of efficacy of these products. Recognizing these demands has led to the development and validation of many clinical methods to measure and quantify ageing skin and the effects of anti-ageing treatments. Many of the current testing methods used to research and evaluate anti-ageing product claim to employ sophisticated instruments alongside more traditional clinical methods. Intelligent use of combined clinical methods has enabled the development of technologically advanced consumer products providing enhanced efficacy and performance. Of non-invasive methods for the assessment and quantification of ageing skin, there is a plethora of tools available to the clinical researcher as defined by key clinically observed ageing parameters: skin roughness and surface texture; fine lines and wrinkles; skin pigmentation; skin colour; firmness and elasticity; hair loss; and proliferative lesions. Furthermore, many clinical procedures for the evaluation of ageing skin treatments are combined with invasive procedures, which enable added-value to claims (such as identification and alteration of biochemical markers), particularly in those cases where perception of product effect needs additional support. As discussed herein, clinical methods used in the assessment of skin ageing are many and require a disciplined approach to their use in such investigations. Résumé Avec les progrès des recherches sur la peau, les consommateurs aujourd'hui ont un accès accru aux informations technologiques concernant le vieillissement de la peau et les produits de soins capillaires. Il en découle une demande rapidement croissante des preuves d'efficacité de ces produits. La reconnaissance de ces demandes a conduit au développement et à la validation de nombreuses méthodes cliniques pour mesurer et quantifier la peau âgée ou le vieillissement de la peau et les effets des traitements anti-âge. Beaucoup des méthodes de test classiques utilisées pour rechercher et évaluer les revendications des produits antivieillissement reposent sur des instruments sophistiqués, à côté des méthodes cliniques plus traditionnelles. La combinaison intelligente de méthodes cliniques a permis le développement de produits commerciaux aux technologies avancées, possédant une efficacité et une performance améliorées. A partir de méthodes non invasives pour la détermination et la quantification des peaux âgées, une pléthore d'outils utilisables par les chercheurs cliniciens a été développée. Elle repose sur les paramètres cliniques-clés observés lors du vieillissement : rêcheur de la peau et texture de surface, ridules et rides, pigmentation de la peau, couleur de la peau, fermeté et élasticité, chute des cheveux et lésions proliférantes. De plus, de nombreuses procédures cliniques pour l'évaluation des traitements des peaux âgées sont combinées à des procédures invasives qui permettent des revendications à valeur ajoutée comme l'identification et l'altération de marqueurs biochimiques, en particulier dans les cas où la perception de l'effet du produit nécessite une argumentation complémentaire. Comme discuté ici, les méthodes cliniques utilisées pour la détermination du vieillissement de la peau sont nombreuses et nécessitent une approche contrôlée pour pouvoir les utiliser dans de telles recherches. [source]

A case of Carney complex

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 12 2006
Junichi Hachisuka MD
Carney complex is a rare syndrome characterized by myxomas, skin pigmentation and endocrine adenomas. We report a case of Carney complex in a 26-year-old man who exhibited skin myxomas on the buttocks, abdomen and neck, and spotty skin pigmentation on the lips. Past medical history revealed that surgical excisions of heart myxomas had been performed twice and calcifications of the testes had been noted. [source]

The latest cosmeceutical approaches for anti-aging

JOURNAL OF COSMETIC DERMATOLOGY, Issue 2007
Zoe Diana Draelos MD
Summary Background, Cosmeceuticals provide a new therapeutic frontier for anti-aging in dermatology. The most dramatic signs of cutaneous aging include the lack of skin surface regularity, the formation of rhagades, and the increased presence of dyspigmentation. Background, The objective of this review is to illustrate how these three needs of maturing skin can be met by novel ingredients incorporated into carefully constructed formulations designed to deliver scientifically measurable and visibly noticeable improvement. Conclusion, Skin surface irregularity can be improved through increased skin turnover facilitated by topical niacinamide, while the appearance of fine lines can be diminished through the application of moisturizers containing engineered peptides and over-the-counter retinoids, such as retinyl propionate. Finally, skin pigmentation can become more regular with the topical application of N-acetyl glucosamine and ultraviolet A photoprotective ingredients. Furthermore, combining cosmeceutical ingredients in a moisturizing vehicle can magnify benefits and profoundly improve skin appearance. [source]

Modern India and the vitamin D dilemma: Evidence for the need of a national food fortification program

MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 8 2010
Uma S. Babu
Abstract India is located between 8.4 and 37.6°N latitude with the majority of its population living in regions experiencing ample sunlight throughout the year. Historically, Indians obtained most of their vitamin D through adequate sun exposure; however, darker skin pigmentation and the changes which have accompanied India's modernization, including increased hours spent working indoors and pollution, limit sun exposure for many. Inadequate sun exposure results in reduced vitamin D synthesis and ultimately poor vitamin D status if not compensated by dietary intake. Dietary vitamin D intake is very low in India because of low consumption of vitamin D rich foods, absence of fortification and low use of supplements. All these factors contribute to poor vitamin D status as measured by low circulating levels of 25-hydroxy vitamin D. Our review searches the published literature specific to India for evidence that would confirm the need to fortify food staples with vitamin D or stimulate public health policies for vitamin D supplementation and dietary guidelines tailored to the Indian diet. This review documents findings of widespread vitamin D deficiency in Indian populations in higher and lower socioeconomic strata, in all age groups, in both genders and people in various professions. Moreover, poor vitamin D status in India is accompanied by increased bone disorders including osteoporosis, osteomalacia in adults and rickets and other bone deformities in children. Without a concerted national effort to screen for vitamin D status, to implement policies or guidelines for vitamin D fortification and/or supplementation and to re-assess recommended dietary intake guidelines, dramatic increase in the number of bone disorders and other diseases may lie ahead. [source]

Effects of sarpogrelate hydrochloride in a patient with chronic graft-versus-host disease: a case report

AMERICAN JOURNAL OF HEMATOLOGY, Issue 2 2006
Tomoe Hayashi
Abstract Chronic graft-versus-host disease (cGVHD) is a frequent complication of allogenic bone marrow transplantation. Even with aggressive treatment, cGVHD is associated with a significant degree of morbidity and mortality. cGVHD resembles autoimmune disorder, particularly systemic sclerosis (SSc). Sarpogrelate hydrochloride (SH) is an antagonist of the 5-hydroxytryptamine2A (5HT2A) receptor and has been reported to be effective in the treatment of systemic sclerosis (SSc) patients with Raynaud phenomenon. We used SH to treat a cGVHD patient, and we measured plasma PDGF and total TGF-, levels. After SH treatment, his plasma PDGF and total TGF-, levels decreased, and he noticed improvement in his skin pigmentation. In the present case, SH may have improved the skin lesion by inhibiting the synthesis of PDGF and TGF-,. Am. J. Hematol. 81:121,123, 2006. © 2006 Wiley-Liss, Inc. [source]

Mitigating Photosensitivity of Erythropoietic Protoporphyria Patients by an Agonistic Analog of ,-Melanocyte Stimulating Hormone,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009
Juergen H. Harms
Erythropoietic protoporphyria (EPP) is a rare hereditary disorder characterized by dermal accumulation of the photosensitizer protoporphyrin IX. Following sunlight exposure, the resulting photosensitivity is manifested first as pain, later as erythema, edema and dermal lesions. Afamelanotide (Nle4 -d-Phe7 -,-MSH), a synthetic analog of ,-melanocyte stimulating hormone and agonist of the melanocortin-1-receptor, promotes melanin synthesis, increasing skin pigmentation. This study examines the efficacy of afamelanotide in preventing symptoms in patients with EPP. A sustained-release subcutaneous implant of 20 mg afamelanotide was administered twice, with a 60-day interval to five EPP patients. Therapeutic efficacy was assessed by a photoprovocation test using standardized white light irradiation, melanin density (MD) determination and daily recording of sunlight exposure and symptoms. From Day 30 to Day 120 tolerance to photoprovocation significantly increased compared with baseline (P = 0.007) and skin MD was significantly higher than that recorded at baseline (P = 0.004). Except for two low-grade pain episodes, patients recorded no phototoxic events past Day 4 of treatment. Tolerance to natural sunlight was up to 24 times longer than prior to therapy. The findings demonstrate beneficial effects of afamelanotide in patients with EPP. Due to the limited number of patients enrolled and the design being an open-label study, confirmation by a large-scale trial is required. [source]

A Case,Sibling Assessment of the Association Between Skin Pigmentation and Other Vitamin D-related Factors and Type 1 Diabetes Mellitus

Standardization of In Vitro Macrophotography for Assessment of Cutaneous Responses

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009
Sergio G. Coelho
The increased popularity of commercially available three-dimensional human skin equivalents in recent years has allowed for assessment of melanogenesis modulated by compounds topically applied to the skin or directly incorporated from the medium. These skin equivalents provide a suitable model for elucidating the mechanisms of action of various factors that modulate skin pigmentation or other properties of the skin. As such, researchers need to objectively quantify cutaneous responses at the macroscopic level. A simple method to standardize macrophotography images is reported that can quantify cutaneous responses in human skin equivalents of Asian, Black or African American, and Caucasian or White racial/ethnic origin. Macrophotographs are analyzed using the Commission Internationale de l'Eclairage L*a*b* color space system in combination with a personal computer and image editing software. Pigmentation changes monitored over a 9 day period showed a high correlation with melanin content evaluated in Fontana,Masson-stained sections. These results indicate the feasibility of using a macrophotography setup in a sterile tissue culture environment to objectively assess in vitro cutaneous responses in human skin equivalents. This serves as an adjunct tool to biochemical and morphological methods to effectively quantify changes in pigmentation over time. [source]

Variables in full-body ultraviolet B treatment of skin diseases

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 3 2010
Hans Christian Wulf
Ultraviolet B (UVB) treatment is most often performed according to a fixed schedule, not necessarily considering important variables such as UV intensity, type of UVB source and skin pigmentation. These variables can rather easily be taken into consideration by the right choice of dosing unit. The advantage of going from dosing in time to Joule to standard erythema dose or to minimal erythema dose is considered. The size of most variables may be diminished considerably. Following these guidelines, it is possible to increase the efficacy of UVB phototherapy without increasing the risk of unintentional burning. [source]

Minimal erythema dose after multiple UV exposures depends on pre-exposure skin pigmentation

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2004
M. Henriksen
Background/purpose: Phototherapy consists of multiple ultraviolet (UV) exposures. Most previous studies have focused on erythema following a single UV exposure in fair-skinned persons. Although it is well known that phototherapy lowers the daily UV-threshold dose for erythema in clinical practice, this is insufficiently documented under controlled experimental conditions. The purpose of this study was to quantify the change in the daily threshold for a dose specific erythema grade after 1,4 consecutive daily UV exposures. Methods: Forty-nine healthy volunteers (skin type II,V) with varying pigmentation quantified by skin reflectance. Two UV sources were used: a narrowband UVB (Philips TL01) and a Solar Simulator (Solar Light Co.). Just perceptible erythema after 24 h was chosen as the minimal erythema dose (+); besides + and ++ were assessed. Results: We found a positive and significant exponential relationship between skin pigmentation and UV dose to elicit a specific erythema grade on the back after 1,4 UV exposures. After repetitive UV exposures the UV dose had to be lowered more in dark-skinned persons compared with fair-skinned persons to elicit a certain erythema grade. This applied to both UV sources and all erythema grades. Conclusion: In the dark-skinned persons the daily UV dose after the 4 days UV exposure should be lowered by 40,50% to avoid burns compared with the single UV exposure. For the most fair-skinned persons essentially no reduction in the daily UV dose was needed. Our results indicate that the pre-exposure pigmentation level can guide the UV dosage in phototherapy. [source]

UV-induced skin changes due to regular use of commercial sunbeds

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2002
J. Ruegemer
Background/aim: Increased pigmentation and thickening of the epidermis are the most important photoprotective skin reactions induced by ultraviolet (UV) radiation. The present study was designed to find out what changes are induced by regular use of commercial sunbeds twice weekly over a period of 6 weeks. Methods: The parameters analysed were skin pigmentation measured by chromametry, minimal erythema dose (MED) as a parameter of light sensitivity, epidermal thickening as determined by histology, induction of keratinocyte apoptosis as determined by TUNEL staining and antioxidant metabolism as measured by changes of cis - and trans -urocanic acid (UCA) content of the skin. Results: As expected, chromametry confirmed the clinically obvious increased skin pigmentation. However, no increase in MED was observed. In addition, neither epidermal thickening nor sunburn cells were seen. Significant detectable changes in proportion of the UCA isomer content of the UV-exposed skin were seen. The total UCA and cis -UCA content increased significantly between nearly all points of measurement. The amount of trans -UCA first decreased, then increased significantly between the different time points. Conclusion: Our data indicate that sunbed-induced tanning is non-protective, which has to be addressed for persons looking for this effect before planning a stay in a sunny climate. However, sunbed-induced tanning may influence immunological reactions. [source]

The role of p53 in pigmentation, tanning and melanoma

PIGMENT CELL & MELANOMA RESEARCH, Issue 5 2008
Neil F. Box
Summary p53 has a central role in skin pigmentation and may impact on melanoma at all stages, however, as it's mutation frequency in melanoma is low, it's role has been somewhat under-appreciated. During normal skin function, p53 in the keratinocyte is a transducer of the skin tanning signal and an essential component of what is effectively a keratinocyte-melanocyte signaling cycle that regulates skin pigmentation. It is clear that this cycle functions optimally in skin of dark pigmentation. When melanin biosynthesis is genetically disrupted in skin of white complexion, we propose that this cycle operates as a promoter of melanocyte proliferation. The cell autonomous function of p53 in melanocytes is not well described, however, the balance of the evidence suggests that p53 is an effective tumor suppressor and the myriad of mechanisms by which the p53 pathway may be dysregulated in tumors attests to it importance as a tumor suppressor. In this review, we outline the known mechanisms that impair p53 itself and its immediate regulators or target genes during melanomagenesis. Due to the importance of this pathway, it is clear that p53 disruptions may relate directly to a patient's prognosis. This pathway will continue to be a focus of investigation, particularly with respect to targeted experimental chemotherapeutics. [source]

Skin Responses to Ultraviolet Radiation: Effects of Constitutive Pigmentation, Sex, and Ancestry

PIGMENT CELL & MELANOMA RESEARCH, Issue 5 2002
Jennifer K. Wagner
Constitutive skin pigmentation and skin responses to ultraviolet radiation were measured on a sample of volunteers (n=250) living in State College, PA, USA. The sample was composed of individuals of European American (n=190), Hispanic (n=45), and East Asian ancestry (n=15). Constitutive pigmentation was measured using the Adjusted Melanin Index (AMI), Erythemal Dose Response (EDR) was measured using the slope of a* at 24 h (,a*), and Melanogenic Dose,Response (MDR) was measured using ,AM, the slope of AMI at 7 d. The relationships between constitutive skin pigmentation, EDR, MDR, sex, age, and ancestry were investigated. European Americans showed a lower constitutive pigmentation, had a significantly higher burn response (EDR), and had a significantly lower tanning response (MDR) than Hispanics and East Asians. No significant difference is seen between Hispanics and East Asians for either constitutive pigmentation or EDR. Constitutive pigmentation in females was slightly lower than in males in all three samples, but the difference was not significant. While no differences were observed in MDR between sexes, males had a stronger EDR than females regardless of population or constitutive pigmentation level, and this difference was significant in European Americans and Hispanics. We observed no age-related differences in any of the populations or measures investigated. We evaluated the relationship between constitutive pigmentation, EDR and MDR. There was a strong inverse correlation between constitutive pigmentation and EDR in the three samples (European Americans, R2=0.176, P < 0.001; Hispanics, R2=0.204, P=0.009; East Asians, R2=0.223, P=0.098) and a strong direct correlation between constitutive pigmentation and MDR in European Americans and Hispanics (European Americans, R2=0.094, P < 0.001; Hispanics, R2=0.164, P=0.012). In other words, persons with lower constitutive pigmentation both burn more and tan less than persons with higher pigmentation. However, after controlling for constitutive pigmentation, EDR and MDR were significantly correlated in European Americans (R2=0.041 P=0.006). Thus, the general observation that persons who burn more tan less is probable because of the common link that these two phenotypes have with constitutive skin pigmentation and, in fact, once pigmentation has been adjusted for, there is a positive correlation between tanning response and burning response in European Americans. [source]

Production of Melanocyte-Specific Antibodies to Human Melanosomal Proteins: Expression Patterns in Normal Human Skin and in Cutaneous Pigmented Lesions

PIGMENT CELL & MELANOMA RESEARCH, Issue 4 2001
Victoria Virador
Multiple factors affect skin pigmentation, including those that regulate melanocyte and/or keratinocyte function. Such factors, particularly those that operate at the level of the melanosome, are relatively well characterized in mice, but the expression and function of structural and enzymatic proteins in melanocytes in human skin are not as well known. Some years ago, we generated peptide-specific antibodies to murine melanosomal proteins that proved to be instrumental in elucidating melanocyte development and differentiation in mice, but cross-reactivity of those antibodies with the corresponding human proteins often was weak or absent. In an effort to characterize the roles of melanosomal proteins in human skin pigmentation, and to understand the underlying mechanism(s) of abnormal skin pigmentation, we have now generated polyclonal antibodies against the human melanocyte-specific markers, tyrosinase, tyrosinase-related protein 1 (TYRP1), Dopachrome tautomerase (DCT) and Pmel17 (SILV, also known as GP100). We used these antibodies to determine the distribution and function of melanosomal proteins in normal human skin (adult and newborn) and in various cutaneous pigmented lesions, such as intradermal nevi, lentigo simplex, solar lentigines and malignant melanomas. We also examined cytokeratin expression in these same samples to assess keratinocyte distribution and function. Immunohistochemical staining reveals distinct patterns of melanocyte distribution and function in normal skin and in various types of cutaneous pigmented lesions. Those differences in the expression patterns of melanocyte markers provide important clues to the roles of melanocytes in normal and in disrupted skin pigmentation. [source]

Genetic admixture, self-reported ethnicity, self-estimated admixture, and skin pigmentation among Hispanics and Native Americans

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009
Yann C. Klimentidis
Abstract The relationship between ethnicity and biology is of interest to anthropologists, biomedical scientists, and historians in understanding how human groups are constructed. Ethnic self-identification in recently admixed groups such as Hispanics, African Americans, and Native Americans (NA) is likely to be complex due to the heterogeneity in individual admixture proportions and social environments within these groups. This study examines the relationships between self-identified ethnicity, self-estimated admixture proportions, skin pigmentation, and genetic marker estimated admixture proportions. These measures were assessed using questionnaires, skin color measurements, and genotyping of a panel of 76 ancestry informative markers, among 170 Hispanics and NAs from New Mexico, a state known for its complex history of interactions between people of NA and European (EU) ancestry. Results reveal that NAs underestimate their degree of EU admixture, and that Hispanics underestimate their degree of NA admixture. Within Hispanics, genetic-marker estimated admixture is better predicted by forehead skin pigmentation than by self-estimated admixture. We also find that Hispanic individuals self-identified as "half-White, half Hispanic" and "Spanish" have lower levels of NA admixture than those self-identified as "Mexican" and "Mexican American." Such results highlight the interplay between culture and biology in how individuals identify and view themselves, and have implications for how ethnicity and disease risk are assessed in a medical setting. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source]

Genetic mapping of the belt pattern in Brown Swiss cattle to BTA3

ANIMAL GENETICS, Issue 2 2009
C. Drögemüller
Summary The white belt pattern of Brown Swiss cattle is characterized by a lack of melanocytes in a stretch of skin around the midsection. This pattern is of variable width and sometimes the belt does not fully circle the body. To identify the gene responsible for this colour variation, we performed linkage mapping of the belted locus using six segregating half-sib families including 104 informative meioses for the belted character. The pedigree confirmed a monogenic autosomal dominant inheritance of the belted phenotype in Brown Swiss cattle. We performed a genome scan using 186 microsatellite markers in a subset of 88 animals of the six families. Linkage with the belt phenotype was detected at the telomeric region of BTA3. Fine-mapping and haplotype analysis using 19 additional markers in this region refined the critical region of the belted locus to a 922-kb interval on BTA3. As the corresponding human and mouse chromosome segments contain no obvious candidate gene for this coat colour trait, the mutation causing the belt pattern in the Brown Swiss cattle might help to identify an unknown gene influencing skin pigmentation. [source]

Characterization of OCA2 cDNA in different porcine breeds and analysis of its potential effect on skin pigmentation in a red Iberian strain

ANIMAL GENETICS, Issue 2 2006
A. Fernández
Summary Although the function of the OCA2 gene product has not been totally clarified, variation in OCA2 has been associated with skin and hair pigmentation in human and mouse. However, its contribution to skin colour in domestic species has not been reported. In this study, cDNA and intron 9 sequences of the porcine OCA2 gene have been characterized in several pig populations. The cDNA sequence alignment of 20 animals from eight porcine populations allowed the identification of 10 single nucleotide polymorphisms (SNPs); five of the 10 SNPs were non-synonymous. The intron 9 sequence alignment of 12 animals belonging to four pig populations revealed four additional SNPs. Skin colour variation was analysed in a red strain of Iberian pigs with segregation of three SNPs forming two OCA2 intragenic haplotypes. Results from this study provide evidence of a suggestive dominant effect of haplotypes on colour intensity and indicate an important contribution of additive polygenic effects (h2 = 0.56 ± 0.21) to the variance of this trait. [source]

Effects of cage netting colour and density on the skin pigmentation and stress response of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

AQUACULTURE RESEARCH, Issue 13 2008
Ben J Doolan
Abstract The unnaturally dark pigmentation of cultured Australian snapper Pagrus auratus can be improved through dietary astaxanthin supplementation and by holding fish in tanks with a white background. The practical application of these laboratory-based findings was examined with two experiments to establish if the advantages of transferring fish to light coloured tanks before harvest could be achieved on-farm using white cages and to determine the effects of fish density on skin colour. For the first experiment, snapper (mean TL=29.7 cm) were transferred from a commercial snapper sea cage to black or white netted cages and fed diets supplemented with unesterified astaxanthin (supplied as Lucantin® Pink, BASF) at 0 or 39 mg kg,1 for 42 days. Skin colour was measured using the CIE (black,white), (green,red), (blue,yellow) colour scale. Snapper held in white netting cages became significantly lighter (higher ) than snapper held in black cages; however, values were not as high as previous laboratory-based studies in which snapper were held in white plastic-lined cages. Snapper fed astaxanthin displayed significantly greater and values, and total carotenoid concentrations after 42 days. In addition, total carotenoids were higher in fish from black than white cages. The second experiment was designed to investigate whether density reduced the improvements in skin colour achieved by holding fish in white coloured cages and whether cage colour affected stress. Snapper (mean weight=435 g) were acclimated to black cages and fed 39 mg kg,1 astaxanthin for 44 days before transferring to black or white plastic-lined cages at 14 (low), 29 (mid) or 45 (high) kg m,3 for 7 days after which time skin colour, plasma cortisol and plasma glucose concentrations were measured. Skin lightness () was greater in snapper transferred to white plastic-lined cages with the lightest coloured fish obtained from the lowest density after 7 days. Density had no effect on plasma cortisol or glucose levels after 7 days, although plasma cortisol was elevated in snapper from black cages. For improved skin colouration we recommend feeding unesterified astaxanthin at 39 mg kg,1 for approximately 6 weeks and transferring snapper to white plastic-lined cages or similar at low densities for short periods before harvest rather than producing fish in white netting sea cages subject to biofouling. [source]

Cage colour and post-harvest K+ concentration affect skin colour of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

AQUACULTURE RESEARCH, Issue 9 2008
Ben J Doolan
Abstract In an attempt to improve post-harvest skin colour in cultured Australian snapper Pagrus auratus, a two-factor experiment was carried out to investigate the effects of a short-term change in cage colour before harvest, followed by immersion in K+ -enriched solutions of different concentrations. Snapper supplemented with 39 mg unesterified astaxanthin kg,1 for 50 days were transferred to black (for 1 day) or white cages (for 1 or 7 days) before euthanasia by immersing fish in seawater ice slurries supplemented with 0, 150, 300, 450 or 600 mmol L,1 K+ for 1 h. Each treatment was replicated with five snapper (mean weight=838 g) held individually within 0.2 m3 cages. L*, a* and b* skin colour values of all fish were measured after removal from K+ solutions at 0, 3, 6, 12, 24 and 48 h. After immersion in K+ solutions, fish were stored on ice. Both cage colour and K+ concentration significantly affected post-harvest skin colour (P<0.05), and there was no interaction between these factors at any of the measurement times (P>0.05). Conditioning dark-coloured snapper in white surroundings for 1 day was sufficient to significantly improve skin lightness (L*) after death. Although there was no difference between skin lightness values for fish held for either 1 or 7 days in white cages at measurement times up to 12 h, fish held in white cages for 7 days had significantly higher L* values (i.e. they were lighter) after 24 and 48 h of storage on ice than those held only in white cages for 1 day. K+ treatment also affected (improved) skin lightness post harvest although not until 24 and 48 h after removal of fish from solutions. Before this time, K+ treatment had no effect on skin lightness. Snapper killed by seawater ice slurry darkened (lower L*) markedly during the first 3 h of storage in contrast with all K+ treatments that prevented darkening. After 24 and 48 h of storage on ice, fish exposed to 450 and 600 mmol L,1 K+ were significantly lighter than fish from seawater ice slurries. In addition, skin redness (a*) and yellowness (b*) were strongly dependent on K+ concentration. The initial decline in response to K+ was overcome by a return of a* and b* values with time, most likely instigated by a redispersal of erythrosomes in skin erythrophores. Fish killed with 0 mmol L,1 K+ maintained the highest a* and b* values after death, but were associated with darker (lower L*) skin colouration. It is concluded that a combination of conditioning snapper in white surroundings for 1 day before harvest, followed by immersion in seawater ice slurries supplemented with 300,450 mmol L,1 K+ improves skin pigmentation after >24 h of storage on ice. [source]