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An interactive effect of visual deprivation and pigmentation on the reactivity of mice to light.

The degree to which mice react to light was measured by comparing open-field activities of mice produced by backcrosses involving A/J and C57BL/6J parental strains under normal white light and under dim red light. This reactivity was markedly enhanced, for pigmented mice, by rearing the animals in the dark: the reactivity of albino mice was unaffected by dark-rearing. Total activity, but not reactivity to light, was found to be influenced by the genotype of the mother, the offspring of hybrid mothers being less active than the offspring of inbred mothers. The findings are discussed in terms of the previously advanced hypothesis that retinal melanin may serve as a photochrome.

Albinism↗

Treatment of the hematological manifestations of dyskeratosis congenita.

Dyskeratosis congenita is a congenital multisystem disorder, characterized by skin pigmentation, dystrophic nails, and leukoplakia. Hematologic abnormalities progressing to severe pancytopenia play a significant role in the poor prognosis of afflicted patients. We report on a patient with dyskeratosis congenita and severe aplastic anemia, complicated by life threatening infection. The patient was treated with recombinant granulocyte-macrophage colony-stimulating factor. This therapy resulted in a moderate and transient improvement in absolute neutrophil counts. Current concepts regarding the pathogenesis and etiology of dyskeratosis congenita are discussed, while reviewing the available therapeutic options.

Anemia, Aplastic↗

Pigment dispersion syndrome in pseudophakic corneal transplants.

We observed the pigment dispersion syndrome in two patients after keratoplasty with posterior chamber intraocular lenses. In addition to a heavily pigmented trabecular mesh-work and iris transilluminating defects, an inferior linear pigmented endothelial line was seen in both patients. One patient developed glaucoma, which was well controlled with medication. Pigment dispersion syndrome in patients with penetrating keratoplasty should not be confused with an allograft reaction but should alert the transplant surgeon that a different process is occurring.

Aged↗

The genetics of pigmentation: from fancy genes to complex traits.

Genes that control mammalian pigmentation interact with each other in intricate networks that have been studied for decades using mouse coat color mutations. Molecular isolation of the affected genes and the ability to study their effects in a defined genetic background have led to surprising new insights into the potential interaction between tyrosine kinase and G-protein-coupled signaling pathways. Recent developments show that homologous genes in humans are responsible not only for rare diseases, such as albinism and piebaldism, but also for common phenotypic variations, such as red hair and fair skin.

Animals↗

Biogenesis of pigment granules: a sensitive way to regulate melanocyte function.

Pigmentation not only provides a wide range of cosmetic coloration to the skin, hair and eyes, but also provides the underlying tissue significant protection from ultraviolet (UV) damage, which can lead to photoaging and photocarcinogenesis. The melanin pigment is synthesized and deposited within a unique, membrane-bound organelle termed the melanosome. Recent advances in molecular biology and biochemistry have allowed a greater appreciation of how melanocytes generate this organelle and how its biogenesis, structure and function is regulated by the environment. Melanosomes serve as ideal models for the study of organelle biogenesis, protein trafficking, organelle movement and cell-cell interactions that occur during the transfer of melanosomes to keratinocytes. Our understanding of the mechanisms behind a wide range of human pigmentary diseases have grown remarkably as melanosomes have been unraveled.

Animals↗

Topical mercurials.

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Administration, Cutaneous↗

Keratinocytes control the proliferation and differentiation of cultured epidermal melanocytes from ultraviolet radiation B-induced pigmented spots in the dorsal skin of hairless mice.

Long-term exposure of ultraviolet radiation B (UVB)-induced pigmented spots in the dorsal skin of hairless mice of Hos:(HR-1 X HR//De) F1. Previous study showed that the proliferative and differentiative activities of cultured epidermal melanoblasts/melanocytes from UVB-induced pigmented spots increased with the development of the pigmented spots. To determine whether the increase in the proliferative and differentiative activities of epidermal melanoblasts/melanocytes was brought about by direct changes in melanocytes, or by indirect changes in surrounding keratinocytes, pure cultured melanoblasts/melanocytes and keratinocytes were prepared and co-cultured in combination with control and irradiated mice in a serum-free culture medium. Keratinocytes from irradiated mice stimulated the proliferation and differentiation of both neonatal and adult non-irradiated melanoblasts/melanocytes more greatly than those from non-irradiated mice. In contrast, both non-irradiated and irradiated adult melanocytes proliferated and differentiated similarly when they were co-cultured with irradiated adult keratinocytes. These results suggest that the increased proliferative and differentiative activities of mouse epidermal melanocytes from UVB-induced pigmented spots are regulated by keratinocytes, rather than melanocytes.

Animals↗

Development of a digital imaging system for objective measurement of hyperpigmented spots on the face.

BACKGROUND/AIMS: There are few available methods that can be used to quantify hyperpigmented spots on a wide area of the face. The objective of this study was to develop such a method through the use of specialized image analysis technologies. METHODS: This imaging system was composed of a source of illumination whose light intensity was controlled with a dimmer, a 3-CCD video camera connected to a computer, and a positioning device used to correctly align the subject's face. This system was calibrated by adjusting the light intensity, the camera position, and white balance of the camera in order to acquire reproducible images. Using a specific algorithm for the image analysis, this system enabled us to measure both the total area of hyperpigmented spots (mm2) and the averaged skin colour tone (quasi L*a*b*) excluding the area of those hyperpigmented spots in a wide area of the face. The accuracy and reproducibility of the system was validated using a mannequin head with six standard colour chips obtained from the GretagMacbeth ColorChecker, and brown-coloured patches that simulated hyperpigmented spots whose colour and area were both known. The correlation between CIE L*a*b* and quasi L*a*b* values was examined by conducting simultaneous measurements of the facial skin colour of 187 subjects with a tristimulus colourimeter (Minolta Chromameter) and our imaging system. RESULTS: The measurement errors in quasi L*a*b* values of colour chips and the area of brown patches were less than 2 and 5%, respectively, unless these chips or patches were located in the peripheral zone of the mannequin head. The variation in quasi L*a*b* values and the area of hyperpigmented spots (mm2) in five repeated measurements performed once every hour was less than 2%. There was an excellent correlation between the CIE L*a*b* and quasi L*a*b* values, and the Pearson's correlation coefficient between CIE L* and quasi L* value, for instance, was 0.908. CONCLUSIONS: : As long as the region to be evaluated is limited to the cheek and periorbital areas, this system enables automatic detection of hyperpigmented spots in a wide area of the face, as well as the correct measurement of those areas and determination of skin colours.

Adult↗