Human skin colour has significant aesthetic and cultural implications. Cutaneous injuries can result in dys-pigmented scars which are more noticeable, aesthetically unpleasant, and can lead to patient distress and social isolation. Management of dys-pigmented scars has been challenging with variable success. There is a limited understanding of the timing, progression and mechanisms of skin re-pigmentation following wounding. This thesis is a detailed sequential study, which describes and quantifies scar colour changes in pigs of different pigmented strains.The first result chapter describes the observational pigmentary changes in scars of four different pigmented pig strains (Hampshire, Yucatan, Tamworth and Duroc) over time. Two scar re-pigmentation progression patterns, specific to the darkly and the lightly pigmented pigs, are identified and all scar photographs of all pigs at all time-points are scored during non-invasive wound/ scar monitoring using a semi-quantitative scale. In the second result chapter, histo-chemical (DOPA-oxidase) staining was combined with immuno-histochemistry (HMB45) to establish the spatial and temporal distribution and activities of melanocytes in the regenerated epithelium of darkly pigmented pig strains. Results suggest a rise in both inactive and active melanocyte numbers in re-pigmenting scars at early time-points and by late time-points, scars achieved ‘complete re-pigmentation’ and melanocyte numbers were lowest. Late melanocyte proliferation was observed in two scars from two different pigs; one of which manifested this as hyper-pigmentation, macroscopically. In addition, histological analysis of the epidermal melanin staining (Warkel-Luna-Helwig) pattern showed good correlation with the macroscopic appearance of the scars. The effect of changes in scar basement membrane undulation on melanocyte packing density was investigated: changes were small and unlikely to impact melanocyte packing density; hence macroscopic scar colour. Macroscopic and microscopic observations of the pattern of re-pigmentation following creation of partial thickness wounds across the white and black belts of three Hampshire pigs were investigated.The final result chapter describes how colour changes were quantified for scars and normal skin of each pig, at all time-points during non-invasive scar monitoring; using a reflectance spectrophotometer. In addition, the sensitivity of objective colour measurements was investigated. Results using two statistical clustering techniques suggest that colour measurements differentiate scars from the surrounding normal skin and the tristimulus L*a*b* values of scars correlate well with their macroscopic colour appearances. Time-dependent colour changes in scars and normal skin were quantified independently, using polynomial analysis. The results suggest systematic colour changes in most scars of all pig groups, except Yucatans’, which on the other hand, showed systematic colour changes to their normal skin. These findings highlight the importance of independent analysis of scar and normal skin colour measurements with time post wounding. In conclusion, this thesis has investigated timing and progression patterns of scar re-pigmentation in pigs of different pigmented strains.

黑色素生成是為了保護皮膚細胞免受紫外光傷害的一個生化過程。在這過程中，黑色素在人類表皮底層的黑色素細胞的黑色素體內產生。該過程可以被基因，荷爾蒙或環境因素所影響。黑色素的製造量是依賴速度限制酶酪氨酸酶的活性，黑色素體的數量和大小，黑色素體通過黑色素細胞的偽足傳送致角質細胞的速度及黑色素體在角質細胞內的分佈。這些細胞過程會受皮膚顏色或紫外光曝光量的變化而影響。當黑色素的產生超過黑色素的降解，黑色素沉著毛病便出現。根據不同的皮膚類型，年齡組別及累積紫外光曝光程度而引發雀斑或黃褐斑的形成。很多治療方法市面上能夠提供，它們包括人工合成化粧品，激光，整容手術等。這些治療方法通常會產生副作用及蘊藏高風險。因此從天然物質裏尋找治療藥物便成了美容學的一個新的研究方向。在這研究裏，十種草本植物就從自古以來用作治療黑色素沉著毛病的傅統中藥中被挑選出來。那些草本植物被四種擁有不同極性的溶劑提取。小鼠黑色素細胞被用以篩選提取物的降黑色素能力。結果發現當歸的正己烷及二氯甲烷的提取物有正面效用。當歸的化學成份4-乙基間苯二酚、4-乙基苯酚及1-十四烷醇也能降低小鼠黑色素細胞的黑色素量。數種生化技術繼而被應用作研究有效化學物的藥理。他們包括西方墨點法、環磷酸腺苷測試、蛋白激酶A活性測試及酪氨酸酶活性測試。 / Melanogenesis is a biochemical process designated for protecting skin cells from ultraviolet (UV)-induced damage. During the process, melanin is produced in the melanosomes of the melanocytes located at the basal epidermis of human. The process could be affected by genetic, hormonal or environmental factors. Amount of melanin synthesized depending on the activity of the rate-limiting enzyme tyrosinase, number and size of melanosomes, the transfer rate of melanosomes to keratinocytes through the melanocyte dendritic projections and the distribution pattern of melanosomes within keratinocytes. These cellular processes are influenced by variations in skin color or UV exposure amount. When melanin synthesis exceeds melanin degradation, hyperpigmentation disorder arises. This lead to the formation of freckles or chloasma according to different skin types, age groups and degree of cumulative UV exposure. A number of treatments are commercially available, they include applying synthetic cosmetics, laser, plastic surgery, etc. These treatments usually produce side-effects and possess high risk. Therefore, searching for therapeutic agents from natural compounds has become a new research direction in cosmetology. In this study, ten herbs were chosen from traditional Chinese medicine (TCM) which had been applied for treating hyperpigmentation. The herbs were extracted by four solvents with different polarity. The extracts were screened for their hypopigmentary ability by using melan-a cells. It was found that the hexane and dichloromethane extracts of Angelica sinensis possessed positive effects. 4-ethylresorcinol, 4-ethylphenol and 1-tetradecanol, the chemical constituents of A. sinensis, also attenuated melanin amount in melan-a cells. Moreover, several biochemical techniques were utilized to study the pharmaceutical mechanisms of the potent compounds. They include Western blot, cyclic adenosine monophosphate (cAMP) assay, protein kinase A (PKA) activity assay and tyrosinase activity assay. / Detailed summary in vernacular field only. / Lam, Rosanna Yen Yen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 127-146). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / Chinese Abstract --- p.iii / Acknowledgements --- p.iv / List of Publications --- p.v / Table of Contents --- p.vi / List of Abbreviations --- p.xii / List of Figures --- p.xv / List of Tables --- p.xviii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Demand of cosmetics --- p.1 / Chapter 1.2 --- Skin structures and functions --- p.1 / Chapter 1.2.1 --- Epidermis --- p.3 / Chapter 1.2.1.1 --- Stratum corneum --- p.4 / Chapter 1.2.1.2 --- Stratum granulosum --- p.4 / Chapter 1.2.1.3 --- Stratum spinosum --- p.4 / Chapter 1.2.1.4 --- Stratum basale --- p.4 / Chapter 1.2.2 --- Dermis --- p.5 / Chapter 1.2.3 --- Hypodermis --- p.5 / Chapter 1.3 --- Sun irradiation --- p.5 / Chapter 1.4 --- Variety of skin types --- p.6 / Chapter 1.5 --- Biochemical reactions within melanocyte --- p.7 / Chapter 1.6 --- Pigmentation disorder --- p.14 / Chapter 1.7 --- From the view of traditional Chinese medicine --- p.16 / Chapter 1.8 --- Treatments available for hyperpigmentation --- p.18 / Chapter 1.9 --- Aims of study and application of strategies --- p.19 / Chapter Chapter 2 --- Investigation of the inhibitory effect of herbal extracts and their constituent compounds on melanin synthesis --- p.20 / Chapter 2.1 --- Introduction --- p.20 / Chapter 2.2 --- Materials and methods --- p.21 / Chapter 2.2.1 --- Materials --- p.21 / Chapter 2.2.2 --- Herbal extraction --- p.23 / Chapter 2.2.3 --- Cell culture --- p.25 / Chapter 2.2.4 --- Growth curve and melanin production curve --- p.25 / Chapter 2.2.5 --- SRB assay --- p.26 / Chapter 2.2.6 --- Calibration curve for SRB assay --- p.27 / Chapter 2.2.7 --- Measurement of melanin production --- p.27 / Chapter 2.2.8 --- Calibration curve for melanin production assay --- p.28 / Chapter 2.2.9 --- Statistical analysis --- p.28 / Chapter 2.3 --- Results --- p.29 / Chapter 2.3.1 --- Growth curve and melanin production curve for assay development --- p.29 / Chapter 2.3.2 --- Calibration curves of SRB assay and melanin production assay --- p.32 / Chapter 2.3.3 --- Hypopigmentary effect of 40 herbal extracts --- p.35 / Chapter 2.3.4 --- Hypopigmentary effects of chemical components of A. sinensis --- p.41 / Chapter 2.4 --- Discussion --- p.49 / Chapter Chapter 3 --- Study of the effect of potential compounds on melanogenic protein expression by Western blot --- p.54 / Chapter 3.1 --- Introduction --- p.54 / Chapter 3.2 --- Materials and methods --- p.56 / Chapter 3.2.1 --- Materials --- p.56 / Chapter 3.2.2 --- Cell culture --- p.56 / Chapter 3.2.3 --- Preparation of cell lysates --- p.57 / Chapter 3.2.4 --- Protein assay --- p.57 / Chapter 3.2.5 --- SDS-PAGE and membrane transfer --- p.58 / Chapter 3.2.6 --- Washing of blotted antibodies and film exposure --- p.59 / Chapter 3.3 --- Results --- p.61 / Chapter 3.4 --- Discussion --- p.70 / Chapter Chapter 4 --- Study of the effect of potential compounds on melanogenic gene expression by RT-PCR --- p.76 / Chapter 4.1 --- Introduction --- p.76 / Chapter 4.2 --- Materials and methods --- p.76 / Chapter 4.2.1 --- Materials --- p.77 / Chapter 4.2.2 --- Cell culture --- p.77 / Chapter 4.2.3 --- RNA extraction --- p.78 / Chapter 4.2.4 --- cDNA synthesis --- p.78 / Chapter 4.2.5 --- PCR --- p.80 / Chapter 4.3 --- Results --- p.83 / Chapter 4.4 --- Discussion --- p.85 / Chapter Chapter 5 --- Study of the effect of potential compounds on cAMP level by EIA --- p.85 / Chapter 5.1 --- Introduction --- p.86 / Chapter 5.2 --- Materials and methods --- p.86 / Chapter 5.2.1 --- Materials --- p.86 / Chapter 5.2.2 --- Cell culture --- p.86 / Chapter 5.2.3 --- Preparation of cell lysates --- p.86 / Chapter 5.2.4 --- Protein assay --- p.87 / Chapter 5.2.5 --- The cAMP assay --- p.88 / Chapter 5.2.6 --- Preparation of cAMP calibration curve --- p.88 / Chapter 5.2.7 --- Calculation --- p.89 / Chapter 5.2.8 --- Statistical analysis --- p.89 / Chapter 5.3 --- Results --- p.90 / Chapter 5.4 --- Discussion --- p.94 / Chapter Chapter 6 --- Study of the effect of potential compounds on PKA activity by PKA activity assay --- p.96 / Chapter 6.1 --- Introduction --- p.96 / Chapter 6.2 --- Materials and methods --- p.96 / Chapter 6.2.1 --- Materials --- p.97 / Chapter 6.2.2 --- Cell culture --- p.97 / Chapter 6.2.3 --- Preparation of cell lysates --- p.98 / Chapter 6.2.4 --- Protein assay --- p.98 / Chapter 6.2.5 --- The PKA kinase activity assay --- p.100 / Chapter 6.2.6 --- Calculation --- p.100 / Chapter 6.2.7 --- Statistical analysis --- p.100 / Chapter 6.3 --- Results --- p.101 / Chapter 6.4 --- Discussion --- p.104 / Chapter Chapter 7 --- Study of the effect of potential compounds on tyrosinase activity by enzyme inhibition assay --- p.107 / Chapter 7.1 --- Introduction --- p.107 / Chapter 7.2 --- Materials and methods --- p.108 / Chapter 7.2.1 --- Materials --- p.108 / Chapter 7.2.2 --- Assay development for mushroom tyrosinase --- p.109 / Chapter 7.2.3 --- Mushroom tyrosinase inhibition assay --- p.109 / Chapter 7.2.4 --- Cell culture --- p.110 / Chapter 7.2.5 --- Preparation of cellular tyrosinase --- p.110 / Chapter 7.2.6 --- Protein assay --- p.111 / Chapter 7.2.7 --- Cellular tyrosinase inhibition assay --- p.111 / Chapter 7.2.8 --- Calculation --- p.112 / Chapter 7.2.9 --- Statistical analysis --- p.112 / Chapter 7.3 --- Results --- p.113 / Chapter 7.4 --- Discussion --- p.120 / Chapter Chapter 8 --- General discussion --- p.123 / References --- p.127

Variation in pigmentation of hair and skin is one of the most striking forms of human diversity. Human pigmentation and sun sensitivity is a complex trait. The melanocortin 1 receptor gene (MC1R) (OMIM 15555) has been shown to be a key determinant of hair and skin colour. Recently a number of other genes have been implicated in human pigmentation. This thesis presents the relationship between human pigmentary phenotypes and genetic variation at MC1R and 34 other candidate loci from 159 individuals. The relationship between experimentally induced cutaneous erythemal and facultative pigmentary response to UVB radiation and MC1R and other pigmentation genotypes was investigated in a subset of 98 individuals. Some of this work involved the development of novel methods of assaying phenotype. I present a detailed description of human pigmentation and facultative pigmentation with respect to a number of key variables (e.g. sex, site, freckling, skin type) and seek to explain the variation in pigmentation in relation to these factors. The effect of MC1R on hair colour is large, but MC1R explains a smaller amount of the variation for skin colour. I found that a number of loci including MC1R, oculocutaneous albinism type 2 OCA2 (OMIM 611409), KIT oncogene ligand KITLG (OMIM 184745) and the Hermansky-Pudlak syndrome 3 HPS3 (OMIM 606118) are determinants of pigmentary phenotype. Some of these findings are in keeping with previous work and some are novel. I present data showing novel SNPs in genes Hermansky-Pudlak syndrome 3 (HPS3) and KIT ligand (KITLG) to be associated with human skin and hair colour variation. Association of HPS3 to eye colour was also found and has to be confirmed in another population. The possible putative mechanisms for the novel association finding in HPS3 are discussed. I am in the process of confirming these positive significant findings in collaboration with another laboratory in Denmark. Further experiments are proposed to confirm other associations and phenotypes.

No description available.

No description available.

Magister Chirurgiae Dentium - MChD / Oral physiological pigmentation presents with great variability with respect to sites, forms, patterns and contrasts in colour. Knowledge of the existence of pigmented lesions and their significance remained unclear for both the general public and oral clinicians alike. The possibility of malignant transformation of some pigmented lesions makes them important to monitor and biopsy. The prevalence of physiological pigmentation is unknown for the defined population group in this study. The results will be beneficial as part of a larger multicentre study with South Africa (Feller et al, 2015). Methodology: A cross sectional analytical study of patients that attended the University of the Western Cape Oral Health centres for routine treatment was conducted. After obtaining informed consent, patients were screened and asked a series of questions using a standardized questionnaire. From these completed questionnaires a prevalence relating to oral physiological pigmentation was determined. Oral physiological pigmentation did not have a male or female predominance in this study population group, but was associated with increased age. Oral pigmentation seemed to be well represented after 18 years of age. Patients were not usually aware of the pigmented gingiva unless being made aware off it.

Pigmentation patterns can be used as a communication signal in a variety of taxa, and can convey information relative to sexual selection, dominance, and species identification. Pigmentation is also sometimes used in mimicry to deceive the signal receiver into thinking the signaler is something other than itself. Mimicry can occur in several contexts, including sexual interactions, where one sex mimics another. There are relatively few examples of species with females that mimic males. Proposed hypotheses to explain female mimicry of males are that mimicry is used to reduce male harassment or that mimicry is used to display dominance over other females. In this study, we tested these two hypotheses using an experimental approach. Researchers have hypothesized that Brachyrhaphis fishes provide an example of sexual mimicry because females have pigmentation of the same coloration and shape, and in the same location as male genitalia. To test if female mimicry of males reduces male harassment, we designed an experiment to observe male preference for females with and without male-like pigmentation. To test the effect that female mimicry of males has on female dominance, we observed female behavior based on the pigmentation patterns of companion females. We found that neither of these hypotheses was supported by our data. We conclude that similarities in anal fin pigmentation between male and female Brachyrhaphis fishes cannot be explained as a way to reduce male harassment of females and is not a good predictor of female dominance interactions. Alternative explanations must exist for this pattern of anal fin coloration include the possibility that these similarities are simply non-adaptive.

Thesis (M.Sc. (Clinical Tropical Medicine))--Mahidol University, 1984.

Extravagant male plumage traits in birds are a classic example of sexual selection. However we know very little about the units that selection is acting upon, the genes themselves – what are they and how are they influenced by sexual selection? In this study I focused on in the evolution and genetics of colouration the galliform birds. Several novel loci were used to create a well resolved phylogeny of this group. This was then used to investigate and reconstruct the evolution of sexual plumage dichromatism. Four pigmentation genes were sequenced in an array of galliform species. A measure of the rate of evolutionary change (dN/dS) at these loci was then compared between lineages with different strengths of sexual selection, using sexual dichromatism as the main index of sexual selection. I found evidence for sexual selection acting at the MC1R locus, in the form of a robust correlation between dN/dS and sexual plumage dichromatism that was not found at any of the other loci. I then went on to investigate the evolution and population genetics of MC1R in the grouse, focusing on the strongly dichromatic black grouse and the relatively monochromatic red grouse. I found some evidence for an adaptive change at this locus between these species. Finally I used a candidate gene approach to investigate the role of several genes in avian pigmentation using the Japanese quail (Coturnix japonica) as a model system. I found evidence that the avian agouti gene is involved in dorso-ventral pigmentation patterning and a regulatory mutation at this locus that produces a yellow phenotype. In addition point mutations at MC1R and TYRP1 were found to be responsible for producing pigmentation variants. I then compared the expression of several of these candidate genes in male and female common pheasants (Phasianus colchicus) and found lower TYRP1 expression in males. Knowledge of the genetic basis of secondary sexual traits and the action of sexual selection at this level could have important implications for our understanding of the process of sexual selection as a whole.

No description available.