Made available in DSpace on 2017-07-24T19:22:07Z (GMT). No. of bitstreams: 1 Wilmer Fabian.pdf: 1250076 bytes, checksum: dc6d549d19b660234c668b167e06c364 (MD5) Previous issue date: 2007-11-08 / The purpose of this study was to determine the color stability of two heat-cured denture base acrylic resins (Lucitone 550 and Vipi Cril) and one nylon denture base material (Transflex) immersed in four liquid foods (coffee, cola, red wine and distilled water). Forty specimen disks of each brand, with a diameter of 20.0 mm and a thickness of 3.0 mm were prepared. Each specimen was suspended in the liquid foods with dental floss so that it did not contact the container or other specimens. The specimens were stored in distilled water for 24 h at 37°C. At that time (T0) the color of all specimens was measured with a spectrophotometer (Varian Cary 100). After 15-day (T1) and 30-day (T2) periods of immersion in the liquid foods color of the specimens was measured again with the spectrophotometer. Color measurements were recorded using the CIEL a b (Commission Internationale de L’ Eclairage) system with D65 (day light) light. Mean ΔE (color changes) values were calculated for each material and compared statistically with a two-way analyses of variance and calculating Bonferroni intervals at 0.95. In ΔE T0T1 and ΔE T0T2 the most severe discoloration was apparent with red wine when compared to the specimens stored in distilled water (P< 0.0001). Coffee was the second staining liquid food which have affect both acrylic and nylon denture base materials. Transflex also showed significant color change after immersion in cola (P < 0.001). In ΔE T1T2 only red wine promoted significant discoloration of all resins (P < 0.0001). From the conclusions of this study, the greatest chromatic change was exhibited by specimens immersed in red wine, followed by coffee. ΔE values of the specimens converted to NBS (National Bureau of Standard) units, showed a visually perceptible color change by these two liquid foods (red wine and coffee). / objetivo deste estudo foi determinar a estabilidade de cor de duas resinas acrílicas (Lucitone 550 e Vipi Cril) e de um material à base de náilon (Transflex) para base de próteses, imersos em três alimentos líquidos (café, refrigerante de cola e vinho tinto, e água destilada, como controle). Quarenta corpos-de-prova em forma de discos de cada marca comercial, com diâmetro de 20,0 mm e espessura de 3,0 mm foram confeccionados. Cada corpo-de-prova foi suspenso dentro do alimento líquido com o uso de um fio dental impedindo o contato com o recipiente ou outros corpos-deprova. Os corpos-de-prova foram armazenados em água destilada por 24 h (T0) a 37 °C. Neste tempo T0, a cor dos corpos-de-prova foi mensurada com espectrofotômetro (Varian Cary 100). Após 15 dias (T1) e 30 dias (T2) de imersão nos alimentos líquidos, a cor dos corpos-de-prova for mensurada novamente com o espectrofotômetro. A mensuração de cor foi registrada usando o sistema CIE L*a*b* (Commission Internationale de L’ Eclairage), com iluminante D65 (luz do dia). Os valores das médias de ΔE (alterações de cor) foram calculados para cada material e comparados estatisticamente com análise de variância de dois fatores e confirmado pelo teste de Bonferroni com intervalos de 0,95. Em ΔE T0T1 e ΔE T0T2 as maiores alterações de cor foram obtidas com o vinho tinto quando comparadas com as dos corpos-de-prova imersos em água destilada (P< 0,0001). O café foi o segundo alimento líquido que alterou a cor tanto das resinas acrílicas quanto da resina à base de náilon. Transflex também demonstrou alteração de cor significativa após a imersão em refrigerante de cola (P < 0,0001). Em ΔE T1T2, somente o vinho tinto promoveu alteração de cor significativa em todas as resinas (P < 0,0001). As conclusões deste estudo demonstram que a maior alteração cromática foi provocada pelo vinho tinto, seguido pelo café. Os valores de ΔE dos corpos-de-prova, convertidos a unidades NBS (National Bureau of Standard), demonstraram alteração de cor visualmente perceptíveis por ambos os alimentos líquidos (vinho tinto e café).

Introdução: O vitiligo é uma doença da pele frequente que afeta cerca de 1% da população em todo o mundo. Ocorre em pessoas de qualquer idade ou etnia, e mais da metade dos pacientes desenvolvem a doença antes dos 20 anos de idade. O vitiligo pode afetar negativamente a qualidade de vida (QoL) do paciente. Um questionário de qualidade de vida específico para vitiligo foi desenvolvido e validado na língua inglesa: the vitiligo-specific quality-of-life instrument (VitiQoL). Objetivo: O objetivo deste estudo é avaliar a QoL em pacientes adultos com o VitiQoL e o DLQI e pediátricos com o CDLQI em uma amostra de pacientes com vitiligo no sul do Brasil. Métodos: Na primeira etapa, o instrumento foi traduzido, adaptado culturalmente e validado para o português falado no Brasil (VitiQoL-PB). Após, foram incluídos pacientes selecionados no Ambulatório de Dermatologia do Hospital de Clínicas de Porto Alegre e numa clínica privada de Porto Alegre. Foi realizada amostragem de conveniência de casos consecutivos. A qualidade de vida de pacientes pediátricos foi avaliada com o questionário CDLQI. Em pacientes adultos foram aplicados o VitiQoL – PB e o DLQI. Resultados: Observou-se uma forte correlação entre os escores do total de VitiQoL e o DLQI (r = 0,81; p <0,001). O fator que mais contribuiu para a pontuação final do VitiQoL foi estigma. Em nossa amostra, as mulheres apresentaram escores mais elevados do que os homens (p <0,05). Problemas psiquiátricos foram associados com uma pior qualidade de vida. Na população pediátrica, a mediana do escore do CDLQI foi 3 (intervalo interquartil 1,3-7,3). Houve uma correlação estatisticamente significativa entre a idade da criança e o escore no CDLQI (rs = 0,41, p = 0,044). Não houve diferença entre meninos e meninas (p = 0,219). Conclusão: Este estudo confirma não só que o VitiQoL é fácil de administrar, como também, acrescenta informações importantes sobre o impacto do vitiligo na América do Sul. Instrumentos genéricos são úteis e permitem comparações com outras dermatoses, mas não são suficientemente específicos para detectar nuances na maneira como os pacientes lidam com o vitiligo. A autoestima dos pacientes é muito afetada e a estigmatização está bastante presente. Há grupos de pacientes que são mais vulneráveis ao impacto da doença, como as mulheres, os adolescentes e os pacientes com doenças psiquiátricas. / Background: Vitiligo is a common skin disease that has been reported to affect approximately 1 % of the population worldwide. It affects people of any age or ethnicity, more than half of who develop it before the age of 20 years. Vitiligo can negatively affect patient’s quality of life (QoL). A specific questionnaire for vitiligo has been developed and validated in the English language: the vitiligo-specific quality-of-life instrument (VitiQoL). Objective: The aim of this study was to access the QoL in adult patients through VitiQoL and DLQI and pediatric patients through CDLQI in a sample of patients with vitiligo in Southern Brazil. Methods: In the first phase of the study the instrument was translated, cultural adapted and validated into Brazilian Portuguese (VitiQoL-PB). Then patients were selected from a Dermatological Outpatient Clinic from Hospital de Clínicas de Porto Alegre and from a Private Practice in Porto Alegre. In this study, we used convenience sampling of consecutive cases. The QoL of pediatric patients was performed using the CDLQI questionnaire. In adult patients we applied the VitiQoL – PB and the DLQI. Results: A strong correlation between the scores of the total VitiQoL and DLQI was observed (r = 0.81; p <0.001). The factor that most contributed to the final score of VitiQoL was stigma. In our sample, women had higher scores than men (p<0,05). Psychiatric problems were associated with lower QoL. In the pediatric population, the median score of CDLQI was 3 (interquartile range 1.3 to 7.3). There was a statistically significant correlation between the child's age and the score on CDLQI (rs = 0.41, p = 0.044). There was no difference between boys and girls (p = 0.219). Conclusion: This study confirms that VitiQoL is easy to administer and adds important information about the impact of vitiligo on a South American population. Generic instruments are useful and allow comparisons with other dermatoses, but are not specific enough to detect nuances in how patients deal with the overall vitiligo burden. Self-esteem of patients is greatly affected and stigmatization is very present in the disease. There are groups of patients that are more vulnerable to the impact of the disease, like women, patients with psychiatric diseases and adolescents.

La peau constitue la première barrière de défense de l'organisme face aux agressions physiques, chimiques et biologiques de l'environnement. Le rôle protecteur de la peau face aux rayonnements solaires ultraviolets, qui constituent la source majeure de dommages de l'ADN des cellules de l'épiderme, est généralement obtenu par la synthèse de la mélanine. La réponse pigmentaire repose ainsi sur la coopération cellulaire observée principalement entre les mélanocytes et les kératinocytes avoisinants. Les mécanismes moléculaires mis en jeu font intervenir les voies classiques de la pigmentation constitutive, déterminant le phototype propre à chaque individu ainsi qu'une voie de signalisation spécifique de la réponse UV. L'implication de la voie de signalisation p38, stress-dépendante, et du facteur de transcription USF-1 dans la régulation de l'expression du gène Tyrosinase, nous a conduit à étudier le rôle du facteur de transcription dans la réponse pigmentaire (Galibert et al., EMBO, 2001). Un ensemble d'expériences (RT-PCR-Quantitative, Immuno-Précipitation de la chromatine, Transfection transitoire...) réalisé in vitro et in vivo (culture cellulaire ou biopsies humaines) et complété d'une approche génétique utilisant une lignée mélanocytaire invalidé pour le gène USF-1, nous a permis d'établir un modèle de régulation de la pigmentation UV induite (Corre et al., JBC, 2004 ; Corre et al., soumis). Enfin, la mise en évidence d'une nouvelle modification post-traductionnelle de la protéine USF-1 en réponse à un stress, dose et temps dépendant, permet d'envisager un nouveau mode de régulation des gènes régulés par USF- 1 (Corre et Galibert, PCR, 2005 ; Corre et al, en préparation). L'ensemble des données obtenues au cours de ma thèse complètent et précisent la fonction du facteur de transcription USF-1 dans la réponse aux stress et suggère un rôle dans le processus tumoral des mélanomes.

A major challenge in the post-genomic era is to understand how genome sequence variants (genotype) give rise to the enormous diversity observed in terms of morphology, physiology and behavior (phenotype) among living organisms. Domestic animals—with their tremendous phenotypic variation—are excellent model organisms for determining the relationships between genotype and phenotype. In this thesis, I describe the utilization of the chicken, in combination with modern genetic and genomic approaches, in developing our understanding of the genetic mechanisms underlying phenotypic variation. These studies provide novel information on the genetics behind variation in carotenoid- and melanin-based pigmentation—observed in many organisms—and also cast light on the genetic basis of chicken domestication. In paper I, we report that the yellow skin phenotype—observed in most commercial chickens—is caused by one or several tissue-specific mutations altering the expression of beta-carotene oxygenase 2 (BCO2 or BCDO2) in skin. In addition, we present the first conclusive evidence of a hybrid origin of the domestic chicken, since the allele causing yellow skin most likely originates from the grey jungle fowl (Gallus sonneratii) and not from the previously described sole ancestor, the red jungle fowl (Gallus gallus). In paper II, we detect a number of loci that were likely important during the domestication process of chicken and the later specialization into meat (broiler) and egg (layer) producing lines. One of the major findings was that worldwide, almost all domestic chickens carry a missense mutation in TSHR (thyroid stimulating hormone receptor) in a position that is completely conserved amongst vertebrates. We speculate that this “domestication-mutation” has played an important role in the transformation of the wild red jungle fowl ancestor into the modern domestic chicken. In paper III, we demonstrate that the dilution of red (pheomelanin) pigmentation—observed in the plumage of the Inhibitor of Gold chicken—is caused by a frame-shift mutation in the catechol-O-methyltransferase domain containing 1 (COMTD1) gene. The production and regulation of pheomelanin is poorly understood and this discovery advances our current knowledge of this pathway.

Melanin is the major component of skin-, hair-, and eye pigmentation in mammals. Synthesis of melanin takes place in specialized organelles in melanocytes, called melanosomes. As melanosomes mature during pigment synthesis, they are transported towards the tips of dendrites in the melanocyte, and eventually transferred to neighbouring keratinocytes to distribute pigment throughout the skin. A large number of proteins regulate melanin synthesis and distribution. Over one hundred genes have been associated with coat colour mutations in mice, and many of these genes have also been identified in human pigmentation disorders. Other proteins involved in pigmentation are part of pathways that are not unique to pigmentation alone, such as the Ras/ERK pathway. In mouse B16 cells, cAMP stimulation leads to the upregulation of melanin synthesis and dendrite extension. However, cAMP also activates the Ras/ERK pathway in these cells, which, upon prolonged stimulation, leads to an inhibition of melanin synthesis and dendrite extension. Here I show that the protein CNrasGEF, which was previously identified in our lab, is responsible for cAMP-dependent Ras activation in B16 cells, and therefore a part of the negative regulatory pathway of melanogenesis. In order to find other proteins involved in pigmentation pathways, I have developed a method to detect melanosomes using Cellomics KineticScan (KSR) high-content image analysis. This system could potentially be used in a high-throughput RNA interference screen to identify proteins that affect melanosome formation or transport. However, in a pilot study it appeared that knockdown levels achieved upon transient transfection of knockdown constructs from a mouse shRNAmir library against selected targets were in many cases not sufficient to detect an effect on melanocytes, either by confocal microscopy, or by Cellomics KSR analysis. Further reduction of expression levels is necessary before this system can be scaled up to high-content/high-throughput identification of proteins involved in pigmentation.

Melanin is the major component of skin-, hair-, and eye pigmentation in mammals. Synthesis of melanin takes place in specialized organelles in melanocytes, called melanosomes. As melanosomes mature during pigment synthesis, they are transported towards the tips of dendrites in the melanocyte, and eventually transferred to neighbouring keratinocytes to distribute pigment throughout the skin. A large number of proteins regulate melanin synthesis and distribution. Over one hundred genes have been associated with coat colour mutations in mice, and many of these genes have also been identified in human pigmentation disorders. Other proteins involved in pigmentation are part of pathways that are not unique to pigmentation alone, such as the Ras/ERK pathway. In mouse B16 cells, cAMP stimulation leads to the upregulation of melanin synthesis and dendrite extension. However, cAMP also activates the Ras/ERK pathway in these cells, which, upon prolonged stimulation, leads to an inhibition of melanin synthesis and dendrite extension. Here I show that the protein CNrasGEF, which was previously identified in our lab, is responsible for cAMP-dependent Ras activation in B16 cells, and therefore a part of the negative regulatory pathway of melanogenesis. In order to find other proteins involved in pigmentation pathways, I have developed a method to detect melanosomes using Cellomics KineticScan (KSR) high-content image analysis. This system could potentially be used in a high-throughput RNA interference screen to identify proteins that affect melanosome formation or transport. However, in a pilot study it appeared that knockdown levels achieved upon transient transfection of knockdown constructs from a mouse shRNAmir library against selected targets were in many cases not sufficient to detect an effect on melanocytes, either by confocal microscopy, or by Cellomics KSR analysis. Further reduction of expression levels is necessary before this system can be scaled up to high-content/high-throughput identification of proteins involved in pigmentation.

Phenotypic plasticity is defined as an organism’s ability to express differentphenotypes depending on the environment. Predation is one of the key forces inecology and can indirectly cause a change of the phenotype in fish populations.Pigmentation change in order to match the background is one type of camouflage usedin fish and other organisms. Moreover, pigmentation might depend on environmentalconditions such as turbidity and water colour that affect the light spectrum and thusthe visibility in the water. The phenotypic variation in body pigmentation of perch(Perca fluviatilis L.) has rarely been studied to this date. In this study, I examined ifbody pigmentation of perch varied between different environments and betweenstructurally different habitats (littoral/pelagic). I tested long-term (phenotypicplasticity) and short-term (physiological-behavioural) changes in pigmentation byusing long-term pre-treatments and short-term aquarium experiments. Differences instructurally-diverse habitats were investigated in an extensive field study.Furthermore, experimental results were compared to data from the field. The resultsshow that pigmentation is determined by environmental factors, such as water colouror turbidity, and by structural complexity. Since fishes adapted their pigmentation totheir visual environment, pigmentation is likely used as predator avoidancemechanism in perch. Moreover, it was demonstrated that the environmentally-inducedpigmentation pattern determines the magnitude of short-term pigmentation in perch.

Dissertation--Düsseldorf--Heinrich-Heine Universität. / Bibliogr. p. 554-580.

Melanin pigmentation is a complex trait governed by many genes. Variation in melanin pigmentation within, and between, populations makes it an important trait for assisting in physical identification of an individual in forensic investigations. Utilizing a training sample (n=789) comprised of various ethnicities and SNPs (75) in 24 genes previously implicated in human or animal pigmentation studies, I determined three-SNP multiple linear regression models that accounted for large proportions of pigmentation variation in skin (45.7%), eye color (76.4%), and hair [eumelanin-to-pheomelanin (43.2%) and total melanin (76.3%)], independent of ethnic origin. Rather than implementing stepwise regression, to ascertain the three-SNP predictive models, I devised an algorithm that is likely more robust than stepwise regression. The algorithm consisted of two steps: the first step reduced the pool of 75 SNPs to a pool of 40 by selection of SNPs that were significant (p<0.05) by one-way ANOVA; the second step enabled selection of SNPs for model incorporation based on their frequency in the best-fitted models of all possible combinations of three-SNP models (i.e., 40 choose 3).Prediction models were validated utilizing an independent cohort (n=242, test sample) that was very similar in ethnic composition to the training sample. Relative shrinkage was moderate for skin reflectance (23.4%), eye color (19.4%), and eumelanin-to-pheomelanin (37.3%) of hair, and largest for total melanin (67%) of hair. Additionally, we refined our model-building algorithm, enabling visual comparison of the frequency and co-linearity due to linkage or co-inheritance of SNPs of the best-fitted models. Application of our algorithm to the test sample yielded the same or similar models as the training sample. Two of the three SNPs composing the models were the same, with some variability in the third SNP of the model.

Skin Pigmentation represents the major natural protection against the deleterious effects of Ultraviolet light and involves a crosstalk between keratinocytes and melanocytes. Pigment synthesis or melanogenesis is initiated by the binding of \(\alpha\)-Melanocyte Stimulating Hormone \((\alpha-MSH)\) to the Melanocortin 1 Receptor (MC1R), expressed by the melanocytes. α-MSH is generated by cleavage of pro-opiomelanocortin hormone (POMC), produced by both melanocytes and keratinocytes. Activation of MC1R leads to an increase in cAMP levels, causing the expression of the transcription factor MITF. MITF regulates the expression of the enzymes involved in melanogenesis as well as genes important for the survival and proliferation of melanocytes. Pigment synthesis, which occurs in specialized organelles called melanosomes, involves the regulation of different proteins as well as fine homeostatic tuning such as melanosomal pH regulation. The POMC derivative, \(\alpha-MSH\), begins the pigmentation pathway by activating the MC1R signaling pathway, and OCA2 regulates the end of this pathway by controlling tyrosinase activity. The OCA2 gene has been shown to be important in the control of intra-melanosomal pH to allow optimal conditions for the activity of Tyrosinase, the limiting enzyme of pigment (melanin) production. OCA2 polymorphisms have been linked to oculocutaneous albinism type 2 and to blue eye color, demonstrating the importance of this gene in fine pH regulation on pigment production. Polymorphisms in POMC have also been linked to red-haired/fair-skin color in humans. Despite the effort to dissect the mechanisms involved in the control of pigmentation, the transcriptional regulation of POMC and OCA2 are still not fully understood. In this study, we investigate the relevance of the cAMP/CREB pathway in the transcriptional regulation of these two proteins. Our data shows that both POMC and OCA2 expression increases after stimulation of the cAMP/CREB pathway. We demonstrate that MITF transcriptionally regulates OCA2: the cAMP/CREB pathway therefore induces OCA2 in a MITF-dependent manner. On the other hand, our data reveals that POMC may be regulated by cAMP in a MITF-independent fashion but consistent with the hypothesis of a positive feedback loop within the MC1R signaling pathway.