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PubMed1990

A 195-kb cosmid walk encompassing the human Xq28 color vision pigment genes.

By using cosmid walking, we have cloned a 195-kb region from chromosome band Xq28 that encompasses the red and green color pigment genes and 85 kb of flanking sequences. This has allowed us to confirm that the color pigment genes are within very homologous units arranged in tandem array. Each unit contains two BssHII sites and one NruI site that are frequently methylated in male leukocyte DNA. A NotI and an EagI site are present 6 kb upstream from the red pigment gene promoter; the NotI site was shown to be unmethylated in the active X chromosome in leukocytes and may represent a CpG island for the whole cluster. We have identified another CpG island, 61 kb 3' from the last green pigment gene, that is unmethylated in leukocytes on the active X chromosome, but methylated on the inactive X. This island is flanked by sequences conserved in evolution and may thus correspond to an expressed gene. We also describe an informative three-allele restriction fragment length polymorphism within the pigment gene cluster.

Biological Evolution↗
PubMed1996

Biochemical basis of lipofuscin, ceroid, and age pigment-like fluorophores.

Serious studies of the formation mechanisms of age-related pigments and their possible cellular influence have been hampered for a long time by discrepancies and controversies over the definition, fluorescence emission, origin, and composition of these pigments. This review discusses several critical controversies in this field and lay special emphasis on the cellular and biochemical reactions related to the formation mechanisms of lipofuscin, ceroid, advanced glycation end-products (AGEs), and age pigment like fluorophores (APFs). Various amino compounds and their reaction with secondary aldehydic products of oxygen free radical-induced oxidation, particularly lipid peroxidation, are important sources of the fluorophores of ceroid/lipofuscin, which progressively accumulate as a result of phagocytosis and autophagocytosis of modified biomaterials within secondary lysosomes of postmitotic and other cells. Lipofuscin is the classical age pigment of postmitotic cells, while ceroid accumulates due to pathologic and experimental processes. There are good reasons to consider both ceroid and lipofuscin as materials of the same principal origin. The age-related intracellular fluorophores of retinal pigment epithelium (RPE) seems to represent a special class of lipofuscin, which partly contains derivatives of retinoids and carotenoids. Saccharide-originated fluorophores, principally AGEs formed during glycation/Maillard reactions, may be mainly responsible for the extracellular fluorescence of long-lived proteins, such as collagen, elastin, and lens crystalline. Although lipofuscin, ceroid, AGEs, and APFs can be produced from different types of biological materials due to different side reactions of essential biology, the crosslinking of carbonyl-amino compounds is recognized as a common process during their formation.

Aging↗
PubMedDate not supplied

Study of a melanic pigment of Proteus mirabilis.

The present study sought to determine whether the pigment produced by Proteus mirabilis from the L-forms of various aromatic amino acids under aerobic conditions is melanic in nature. It is a black-brown pigment which behaves like a melanin in many respects, namely solubility features, bleaching by oxidizing agents and positive response to the Fontana-Masson assay. In the present study, for the first time, it was shown by electron spin resonance analysis that a bacterial melanin is able to act as a free radical trap, as was previously demonstrated for other melanins. Scanning electron microscopy studies showed a specific organized structure of the pigment as rounded aggregates of spherical bodies. DNA hybridization data did not reveal, in the P. mirabilis genome, any nucleotide sequence related to Shewanella colwelliana mel A, one of the two melanogenesis systems already defined at the molecular level in bacteria. Results obtained from experiments on pigment production inhibition suggest a possible role of tyrosinase in P. mirabilis melanogenesis. In conclusion, from the bulk of our results, it appears that the pigment produced by P. mirabilis is melanic in nature.

DNA, Bacterial↗
PubMed2004

Visualization of retinal pigment epithelial cells in vivo using digital high-resolution confocal scanning laser ophthalmoscopy.

PURPOSE: To visualize retinal pigment epithelial cells in vivo by fundus autofluorescence imaging using a confocal scanning laser ophthalmoscope. DESIGN: Experimental study and observational case report. METHODS: Digital in vivo autofluorescence images were recorded with a confocal scanning laser ophthalmoscope (excitation, 488 nm; emission, >500 nm) and compared with confocal scanning laser ophthalmoscope and fluorescence microscopic recordings from human donor eyes. RESULTS: A uniform pattern of the polygonal retinal pigment epithelial cell layer was visualized in vivo outside of absorbing retinal vessels and macular pigment. Autofluorescence intensities of individual cells showed marked variation. The pattern corresponded to in vitro findings. Visualization is based on the topographic distribution of autofluorescent lipofuscin granules and melanin granules in apical retinal pigment epithelium cytoplasm. CONCLUSIONS: High-resolution autofluorescence imaging may be useful to determine morphologic and lipofuscin-dependent alterations in retinal diseases and may be applicable for monitoring effects of therapeutic interventions targeting the retinal pigment epithelium.

Aged↗
PubMed2005

Cancer-associated nummular loss of the pigment epithelium.

PURPOSE: To report a case of bilateral diffuse uveal melanocytic proliferation (BDUMP) that had areas of retinal pigment epithelial loss. DESIGN: Observational case report. METHODS: A 67-year-old woman with a history of uterine cancer presented with 4 months of bilateral visual loss. RESULTS: Although B-scan ultrasonography revealed both small shallow serous retinal and choroidal detachments in the periphery, the choroid was normal in thickness. Fluorescein angiography revealed numerous nummular-shaped areas of transmission defects suggesting retinal pigment epithelium loss. Autofluorescence photography showed complete absence of autofluorescence in these nummular areas, and optical coherence tomography showed segmental areas with lack of any signal from affected areas of the retinal pigment epithelium, suggesting complete loss of retinal pigment epithelium cells. CONCLUSIONS: Although the fundus findings in BDUMP have been attributed to the proliferation of uveal melanocytic cells in the outer choroid in previous papers, our patient had nummular areas of loss of the retinal pigment epithelium as the apparent reason for visual decline.

Aged↗
PubMed2005

Spontaneous rip of the retinal pigment epithelium with a macular hole in neovascular age-related macular degeneration.

PURPOSE: To report a case of retinal pigment epithelial tear associated with a macular hole in a patient with neovascular age-related macular degeneration (AMD). DESIGN: Observational case report. METHODS: An 87-year-old woman with AMD-related fibrovascular pigment epithelial detachment associated with vision loss was followed with sequential fundus photography, fluorescein angiography, and optical coherence tomography for 8 months. RESULTS: The detachment developed into a retinal pigment epithelium tear with macular hole formation. The temporal evolution of the lesion and optical coherence tomography findings suggested that the retinal pigment epithelium tear led to stretching forces along the posterior surface of the neurosensory retina with secondary foveal dehiscence. CONCLUSION: Macular hole formation is one mechanism by which retinal pigment epithelium tears may cause vision loss in AMD.

Aged↗
PubMed2005

Changes in retinal pigment epithelium after indocyanine green-assisted internal limiting lamina peeling during macular hole surgery.

PURPOSE: To determine the changes in the retinal pigment epithelium (retinal pigment epithelium) and secondary changes in the choroid and fovea after indocyanine green (ICG) staining of the internal limiting lamina during surgery for an idiopathic macular hole (MH). DESIGN: Observational case series. METHODS: The medical charts of 31 patients who underwent MH surgical procedures with internal limiting lamina staining and peeling were reviewed. The eyes were examined by optical coherence tomography, scanning laser ophthalmoscopy, fluorescein, and ICG angiography. RESULTS: In three cases that experienced retinal pigment epithelium changes, there was foveal thinning and choriocapillary atrophy in the area of the previous MH. The visual acuity was markedly worse, and the retina was markedly thinner in these three cases than in the other cases without retinal pigment epithelium changes (P = .003, P = .009, respectively). CONCLUSION: The use of ICG dye with illumination may increase the risk of retinal pigment epithelium damage and secondary choroidal and foveal morphologic changes.

Basement Membrane↗
PubMed2006

Retinal pigment epithelium tear after intravitreal bevacizumab for exudative age-related macular degeneration.

PURPOSE: To report on the development of retinal pigment epithelium tears after intravitreal injections of bevacizumab as treatment of exudative age-related macular degeneration (AMD). DESIGN: Interventional case series. METHODS: The study included 63 patients who received an intravitreal injection of 1.5 mg bevacizumab as treatment of a detachment of the retinal pigment epithelium attributable to AMD and who had a follow-up of at least two months. RESULTS: Four patients (6%) developed a tear of the retinal pigment epithelium in the parafoveal region. Compared with the baseline value, visual acuity at the end of follow-up remained stable in three patients and declined in the fourth patient. CONCLUSIONS: Intravitreal injections of bevacizumab may be followed by a tear of the retinal pigment epithelium in eyes with exudative AMD and a retinal pigment epithelium detachment.

Angiogenesis Inhibitors↗
PubMed2004

Studies of orthodontic elastomeric modules. Part 1: glass transition temperatures for representative pigmented products in the as-received condition and after orthodontic use.

The purpose of this study was to investigate the glass transition temperatures (T(g)) of representative elastomeric chain products (plastic modules) in the as-received condition and after orthodontic use to determine differences between brands and pigments. Values of T(g) were determined by differential scanning calorimetry. Products were obtained from 3 manufacturers: Rocky Mountain Orthodontics (RMO, Denver, Colo), Ormco (Glendora, Calif), and G&H (Greenwood, Ind). Three colors (gray, red, and purple) were selected for each brand-pigment combination to evaluate the as-received products, and test specimens for each brand-pigment combination from the same batches were placed in patients' mouths for 4 weeks to evaluate the products after clinical use (sample size of 7 specimens for both groups of experiments). Results were analyzed statistically by multiple nonparametric Mann-Whitney tests. A post hoc step-down Bonferroni analysis followed, to examine differences in T(g) due to pigmentation within brands and differences due to brands within each pigmentation category. For the as-received products, the RMO modules had mean T(g) ranging from -24 degrees C to -21 degrees C, whereas the Ormco and G&H modules had significantly lower mean T(g), ranging from -46 degrees C to -39 degrees C, indicating substantial compositional or polymer structural differences compared with the RMO modules. After clinical use, the RMO products had mean T(g) ranging from -31 degrees C to -25 degrees C, whereas the Ormco and G&H products had mean T(g) ranging from -46 degrees C to -30 degrees C. The in vivo specimens also exhibited a second, higher-temperature glass transition of unknown origin. Results suggest that the Ormco and G&H products should have greater flexibility than the RMO products and that there should be significant differences in clinical force-degradation behavior for the Ormco and G&H products compared with the RMO products.

Color↗
PubMed2005

Yellow pigments used in rapid identification of aflatoxin-producing Aspergillus strains are anthraquinones associated with the aflatoxin biosynthetic pathway.

Studies on biological control of aflatoxin production in crops by pre-infection with non-toxigenic Aspergillus flavus strains have created a need for improved methods to screen isolates for aflatoxigenicity. We have evaluated two empirical aflatoxigenicity tests: (i) yellow pigment production, and (ii) the appearance of a plum-red color in colonies exposed to ammonium hydroxide vapor. Yellow pigments from aflatoxigenic A. flavus were shown to function as pH indicator dyes. Seven pigments representing most of the pigmentation in extracts have been isolated using color changes when chromatography spots were exposed to ammonium hydroxide vapor to guide fractionation. Their structures have been shown to be norsolorinic acid, averantin, averufin, versicolorin C, versicolorin A, versicolorin A hemiacetal and nidurufin, all of which are known anthraquinone pigments on, or associated with, the aflatoxin biosynthetic pathway in Aspergillus spp. Thus, the basis of both empirical tests for aflatoxigenicity is detecting production of excess aflatoxin biosynthetic intermediates.

Aflatoxins↗
PubMed2004

Determination of pigments in vegetables.

Plant pigments are responsible for the shining color of plant tissues. They are also found in animal tissues and, eventually in transformed food products as additives. These pigments have an important impact on the commercial value of products, because the colors establish the first contact with the consumer. In addition plant pigments may have an influence on the health of the consumers. Pigments are labile: they can be easily altered, and even destroyed. Analytical processes have been developed to determine pigment composition. The aim of this paper is to provide a brief overview of these methods.

Chromatography, Liquid↗
PubMed2006

In situ estimation of the entire color and spectra of age pigment-like materials: application of a front-surface 3D-fluorescence technique.

Fluorescent characteristics of age pigment-related materials were re-examined with improved techniques. A series of fluorescent colors, from blue to yellow-red were observed in artificial ceroid/lipofuscin. A front-surface accessory attached to a spectrofluorometer was found very useful in studying the age pigment-like aggregates directly in its solid state. With a three-dimensional (3D)-fluorescence measurement, in addition to the front-surface application, entire fluorescence spectra of artificial ceroid/lipofuscin both in extractions and in non-extractable tissues were obtained. When the front-surface 3D-scan technique was applied to estimate collagen-related age pigments of rat-tails in situ, a dynamic process of age-related protein deterioration accompanied with age pigment development was recorded. The front-surface 3D-fluorescence technique introduced in this study may be used as a practical and effective tool in studying in situ pigment alterations during aging process.

Aging↗
PubMed2004

Iris pigment epithelial cells: a possible cell source for the future treatment of neurodegenerative diseases.

For the treatment of neurodegenerative disorders such as Parkinson's disease cell or gene therapeutical options are increasingly verified. For such approaches, neural stem cells or astrocytes are discussed as possible cell candidates. As also fetal retinal pigment epithelial cells have been successfully tested for such therapeutical options, we investigated the potential of iris pigment epithelial cells as an autologous source for future cell replacement therapies. Using the ELISA technique, we looked for the secretion of neurotrophic factors under basal and stimulated conditions by iris pigment epithelial cells (IPE) cells and compared them with the secretion of retinal pigment epithelial cells (RPE) cells. As iron plays a causative role in cell death during Parkinson's disease, the iron-binding capacity by IPE cells was investigated. Furthermore, we checked the integrative capacity of IPE cells after transplantation into the striatum of adult rats. Our data reveal that IPE cells produce and secrete a variety of neurotrophic factors which can be stimulated after treatment with cytokines. Following transplantation, the cells can be easily detected by their pigmentation, survive for at least 8 weeks and as shown by electron microscopy integrate within the host tissue. Moreover, cells can be transduced with high efficiency using a third generation adenoviral vector, making them promising vehicles to locally deliver therapeutic proteins for the treatment of neurodegenerative diseases in a combined cell and gene therapeutical approach.

Animals↗
PubMed2004

A carotenoid-binding protein (CBP) plays a crucial role in cocoon pigmentation of silkworm (Bombyx mori) larvae.

We examined the role of carotenoid-binding protein (CBP) in yellow cocoon pigmentation. First, using yellow or white cocoon races, we investigated the linkage between the yellow pigmentation and CBP expression. CBP was expressed only in the silk gland of the yellow cocoon races, which utilize carotenoids for cocoon pigmentation. Furthermore, CBP expression in the silk glands of day 1-7 fifth instar larvae matched the period of carotenoid uptake into the silk gland. Finally, we gave double-stranded CBP RNA to Bombyx mori (B. mori) larvae to induce RNA interference. The significantly reduced expression of CBP in the silk gland of fifth instar larva was confirmed on day 4 and a decrease in yellow pigmentation was observed in the cocoon. We showed that CBP plays a key role in the yellow cocoon pigmentation caused by carotenoids.

Animals↗
PubMed2004

Tubercle bacilli generate a novel cell wall-associated pigment after long-term anaerobic culture.

Many cases of tuberculosis result from reactivation of previously acquired latent infections. Models to study such persister forms often involve gradual depletion of oxygen during culture as poor aeration is a characteristic of non-progressive TB granulomas. Anaerobically cultured bacilli develop a thickened outer-most cell wall layer. Here, we analyzed this layer from anaerobically cultured Mycobacterium tuberculosis and Mycobacterium bovis BCG. By six weeks of anaerobiosis a pigment was detected at levels > 60-fold higher in anaerobic than aerobic bacilli. This pigment was responsible for the electron-dense appearance of the thickened cell wall layer and gave an electrospray mass spectrometry peak at 409 Da (M+Na)+ or (M+H)+. We termed this pigment APP1, anaerobically produced pigment 1, the first pigment identified in M. tuberculosis.

Anaerobiosis↗
PubMed2006

Iris and trabecular meshwork pigment changes after posterior chamber phakic intraocular lens implantation.

PURPOSE: To evaluate the changes in laser iridotomies, intraocular pressure (IOP), angle structures, and pupil diameter after implantable contact lens (ICL) (Version 4 Staar Surgical) implantation in myopic Asian eyes. SETTING: Department of Ophthalmology, Chung-Ang University Yongsan Hospital, Seoul, Korea. METHODS: The ICL was implanted in 81 eyes of 43 patients with spherical equivalent greater than -6.00 diopters. Gonioscopy examination was performed 1 day after laser iridotomy and 6 and 12 months after ICL implantation. The changes in laser iridotomy sites, IOP, and pupil diameter were also evaluated. RESULTS: Ten eyes (12.3%) had occlusion or narrowing of the laser iridotomy sites. The angle width was more than 30 degrees in all cases preoperatively but narrowed to less than 20 degrees in 16 eyes (19.8%) 6 months postoperatively. The mean pigment, measured by the semiquantitative method (grade 0 to 4), was 2.03 in the inferior angle, 0.18 in the nasal angle, 0.12 in the temporal angle, and 0.00 in the superior angle 12 months postoperatively. The pigment in all quadrants increased temporally as a result of the laser iridotomy or iris rubbing by the ICL; however, the pigments absorbed gradually and decreased to values before laser iridotomy 12 months postoperatively. There was a temporary increase in IOP from the instillation of steroid eyedrops 1 week and 1 month postoperatively; IOP returned to the preoperative level and remained there 12 months postoperatively. There was a significant decrease in pupil diameter 1 and 3 months postoperatively; the diameter returned to the preoperative size at 6 and 12 months. Pigment dispersion syndrome and pigmentary glaucoma were not seen. CONCLUSION: Implantation of the ICL narrowed the angle width but did not increase trabecular pigmentation compared with values after laser iridotomy, indicating ICL implantation is safe regardless of the pigmentary changes in the trabecular meshwork.

Adult↗
PubMed2006

A new lipophilic pro-vitamin C, tetra-isopalmitoyl ascorbic acid (VC-IP), prevents UV-induced skin pigmentation through its anti-oxidative properties.

BACKGROUND: Vitamin C, which is a strong anti-oxidant, plays an important role in maintaining physiological states. In dermatology, Vitamin C is used for treatment of various skin problems such as de-pigmentation of hyperpigmented spots. However, Vitamin C has limited stability and permeability, and development of a Vitamin C derivative with improved properties is needed. OBJECTIVE: We evaluated the effect of a lipophilic Vitamin C derivative, tetra-isopalmitoyl ascorbic acid (VC-IP), on ultraviolet (UV)-induced skin pigmentation, to determine its potential as a more effective form of Vitamin C. METHODS: The release of Vitamin C from VC-IP was examined using a reconstructed skin model following topical application of VC-IP. Anti-oxidative and anti-inflammatory activities of VC-IP were tested in cultured human keratinocytes. Subsequently, clinical test was done to clarify the effect of VC-IP on UVB-induced skin pigmentation. RESULTS: VC-IP released Vitamin C in physiological conditions and worked as pro-Vitamin C. In subsequent experiments, we found that VC-IP suppressed the elevation of intracellular peroxide after UVB irradiation, and enhanced cellular tolerance against UVB and reactive oxygen species such as hydrogen peroxide and tert-butyl hydroperoxide. Furthermore, VC-IP reduced the production of interleukin-1alpha and prostaglandin E2 in UVB-irradiated keratinocytes and suppressed melanocyte proliferation in conditioned culture medium prepared from UVB-irradiated keratinocytes. Finally, in a clinical study, topical application of a 3% VC-IP cream for 3 weeks suppressed pigmentation after UVB irradiation. CONCLUSIONS: These results demonstrate that VC-IP is a precursor of Vitamin C, and effectively suppresses UVB-induced skin pigmentation, possibly through its anti-oxidative activity.

Adult↗
PubMed2004

Hair cycle and hair pigmentation: dynamic interactions and changes associated with aging.

The tight coupling of hair follicle melanogenesis to the hair growth cycle dramatically distinguishes follicular melanogenesis from the continuous melanogenesis of the epidermis. Cyclic re-construction of an intact hair follicle pigmentary unit occurs optimally in all scalp hair follicles during only the first 10 hair cycles, i.e. by approximately 40 years of age. Thereafter there appears to be a genetically regulated exhaustion of the pigmentary potential of each individual hair follicle leading to the formation of true gray and white hair. Pigment dilution results primarily from a reduction in tyrosinase activity within hair bulbar melanocytes. Thereafter, sub-optimal melanocyte-cortical keratinocyte interactions, and defective migration of melanocytes from a reservoir in the upper outer root sheath to the pigment-permitting microenvironment close to the follicular papilla of the hair bulb, will all disrupt normal function of the pigmentary unit. Evidence from studies on epidermal melanocyte aging suggest that reactive oxygen species-mediated damage to nuclear and mitochondrial DNA may lead to mutation accumulation in bulbar melanocytes. Parallel dysregulation of anti-oxidant mechanisms or pro/anti-apoptotic factors is also likely to occur within the cells. Pigment loss in canities may also affect keratinocyte proliferation and differentiation, providing the tantalizing suggestion that melanocytes in the hair follicle contribute far more that packages of pigment alone. Here, we review the current state of knowledge of the development, regulation and control of the aging human hair follicle pigmentary system in relation with hair cycling. The exploitation of recently available methodologies to manipulate hair follicle melanocytes in vitro, and the observations that melanocytes remain in senile white hair follicles that can be induced to pigment in culture, raises the possibility of someday reversing canities. The perspective of rejuvenation of the whole hair follicle apparatus are still part of the dream but optimising its functional properties is clinically relevant and is close to reality. Finally as hair color influences its visibility when optical methods such as scalp photography are used to count hair fibers, the attention is drawn to possible interpretations of statistically significant changes in visible hair. Such changes may not exclusively be related to improved hair growth itself but also to changes in natural hair color that makes the hair more visible with the method used to count hairs.

Adult↗