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PubMed2000

Hyperfluorescence associated with serous retinal pigment epithelial detachment on indocyanine green angiography.

PURPOSE: Indocyanine green angiography has been reported to improve detection and delineation of occult choroidal neovascularisation in serous pigment epithelium detachment in age-related macular degeneration. The study aims to evaluate the visual acuity results of eyes affected by serous pigment epithelium detachment in age-related macular degeneration, having had indocyanine green-directed laser photocoagulation, and to correlate them to the pattern of serous pigment epithelium detachment on indocyanine green angiography. METHODS: Thirty-four eyes of 31 patients affected by serous pigment epithelium detachment in age-related macular degeneration were prospectively considered. Each patient underwent an ophthalmological examination including fluorescein and indocyanine green angiography one day before, and 6 weeks, 3 months, 6 months, 9 months, 12 months and 24 months after krypton-laser treatment. The serous pigment epithelium detachment was classified in the late-phases angiograms as either hypofluorescent, isofluorescent or hyperfluorescent comparing the fluorescence of the serous pigment epithelium detachment with the choroidal background fluorescence. RESULTS: The indocyanine green-guided laser treatment was associated with a temporary stabilization and a long-term progressive reduction of visual acuity: after 24 months visual acuity improved in 2.9%, stabilized in 26.5% and worsened in 70.5% of cases. Serous pigment epithelium detachment presenting a pretreatment hyperfluorescence had a final visual acuity of 0.06, with subfoveal choroidal neovascularisation development in 100% of cases, whereas serous pigment epithelium detachment presenting a pretreatment hypofluorescence and isofluorescence showed a final visual acuity of 0.12, with subfoveal choroidal neovascularisation development in 43.5% of eyes, with statistically significant difference. CONCLUSION: Overall visual acuity decreases with time after indocyanine green-guided laser treatment of choroidal neovascularisation in serous pigment epithelium detachment, and serous pigment epithelium detachment becoming hyperfluorescent in the late-phases of indocyanine green angiography has the worst functional outcome.

Aged↗
PubMed2001

Production of brown tyrosine pigments by the yeast Yarrowia lipolytica.

AIMS: To study the mechanism of production of brown pigments from tyrosine in the yeast Yarrowia lipolytica. METHODS AND RESULTS: Pigment formation was followed during growth in tyrosine medium, and the presence of the pigment precursor in the medium was assessed by evaluating pigment formation after removing the cells at different times of incubation. It was observed that the pigment precursor accumulated outside the cells during the exponential phase of growth, but pigment formation only occurred during the stationary phase of growth and resulted from the oxidation of the precursor. Pigment formation was repressed by glucose and L-glutamine, and promoted by lactic acid, L-asparagine and glycine. Spectra of 1H and 13C-NMR revealed that the brown pigment was derived from tyrosine and was a polymer composed of a core of aromatic residues. CONCLUSION: The results indicate that pigments result from the extracellular accumulation and auto-oxidation of an intermediate of tyrosine catabolism. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the mechanism of pigment production from tyrosine in a yeast species.

Cheese↗
PubMed1998

Role of cell adhesion in the specification of pigment cell lineage in embryos of the sea urchin, Hemicentrotus pulcherrimus.

To clarify the role of cell adhesion in the specification of pigment cell lineage in sea urchin embryos, cell contacts were inhibited by Ca2+-free artificial seawater (ASW) treatment, and the number of differentiated pigment cells was examined by the method devised for the present study. Obtained results showed that inhibition of cell contacts during mid-to-late blastula stage greatly affects the number of pigment cells. Treatment with Ca2+-free ASW during 7.5-10.5 h of development drastically decreased the number of pigment cells, indicating that cell adhesion during this period is indispensable for the specification of pigment cell lineage. On the other hand, the number of pigment cells were increased by the treatment during 9.5 12.5 h of development. It was suggested that this increase was caused by excess divisions of the precursor cells, that is, the division schedule of the precursor cells was altered by inhibition of cell contacts at this period. Interestingly, the number of pigment cells was a multiple of four in a majority of embryos in which pigment cells were drastically decreased in number. These findings suggest that the founder blastomeres of the pigment cell lineage are specified during 7-10 h of development, and that these blastomeres divide twice before they differentiate into pigment cells.

Animals↗
PubMed2002

Ecological-friendly pigments from fungi.

The dyestuff industry is suffering from the increases in costs of feedstock and energy for dye synthesis, and they are under increasing pressure to minimize the damage to the environment. The industries are continuously looking for cheaper, more environmentally friendly routes to existing dyes. The aim of this minireview is to discuss the most important advances in the fungal pigment area and its interest in biotechnological applications. Characteristic pigments are produced by a wide variety of fungi and the chemical composition of natural dyes are described. These pigments exhibit several biological activities besides cytotoxicity. The synthetic pigments authorized by the EC and in USA and the natural pigments available in the world market are discussed. The obstacle to the exploitation of new natural pigments sources is the food legislation, requesting costly toxicological research, manufacturing costs, and acceptance by consumers. The dislike for novel ingredients is likely to be the biggest impediment for expansion of the pigment list in the near future. If the necessary toxicological testing and the comparison with accepted pigments are made, the fungal pigments, could be acceptable by the current consumer. The potentiality of pigment production in Brazil is possible due to tremendous Amazonian region biodiversity.

Environment↗
PubMed1997

Visual pigment gene structure and expression in human retinae.

We determined the genotypes of the X-chromosome-linked red/green color vision genes by a novel PCR/SSCP-based method and assessed expression by mRNA analysis in retinae of 51 unselected post mortem eye specimens from Caucasian males of unknown color vision status. All individuals had a single red (long-wave) pigment gene and one or more (an average of two) green (middle-wave) pigment genes. Four males had 5'green-red3' hybrid genes in addition to normal red and green pigment genes. These findings are consistent with earlier studies on human visual pigment gene structure using Southern blotting and with a recent study using pulsed-field electrophoresis. We interpret claims of much larger numbers of red, green and green-red hybrid genes to be technical artifacts. The ratio of expressed red to green pigment retinal mRNA varied widely (1-10 with a mode of 4) and was not correlated with that of red to green pigment genes. In one individual with a green-red hybrid gene in addition to normal red and green pigment genes, the normal red pigment gene and the hybrid gene were both expressed, but the normal green gene was not. This person presumably had deuteranomalous color vision. Two with green-red hybrid genes expressed the normal red and green pigment genes, but not the hybrid genes. These two individuals presumably had normal color vision. We interpret the failure to express their green-red hybrid genes to be caused by their location at a more distal position in the visual pigment gene array.

Color Vision Defects↗
PubMed1989

Molecular evolution of human visual pigment genes.

By comparing the published DNA sequences for (a) the genes encoding the human visual color pigments (red, green, and blue) with (b) the genes encoding human, bovine, and Drosophila rhodopsins, a phylogenetic tree for the mammalian pigment genes has been constructed. This evolutionary tree shows that the common ancestor of the visual color pigment genes diverged first from that of the rhodopsin genes; then the common ancestor of the red and green pigment genes and the ancestor of the blue pigment gene diverged; and finally the red and green pigment genes diverged from each other much more recently. Nucleotide substitutions in the rhodopsin genes are best explained by the neutral theory of molecular evolution. However, important functional adaptations seem to have occurred twice during the evolution of the color pigment genes in humans: first, to the common ancestor of the three color pigment genes after its divergence from the ancestor of the rhodopsin gene and, second, to the ancestor of the red pigment gene after its divergence from that of the green pigment gene.

Amino Acid Sequence↗
PubMed1987

Relationship between pigment production and haemolysin formation by Lancefield group B streptococci.

Group B streptococci produce both a pigment and a haemolysin. The requirements of group B streptococci for the formation and release of pigment and haemolysin are similar and have been examined to extend observations on the relationship between the two products. The amount of pigment and haemolysin extractable from actively metabolising washed-cell suspensions of group B streptococci varied with the atmosphere of incubation, the pH at which the extraction was carried out and the presence of Mg2+ ions. Both pigment and haemolysin were produced in significant amounts in all phases of the growth cycle. When conditions were established for obtaining maximum yields of haemolysin, its production correlated closely with pigment yields, but pigment did not function as a carrier for haemolysin. Formation of pigment, but not of haemolysin, increased in the presence of trimethoprim or higher concentrations of glucose. The composition of pigment produced in different conditions differed qualitatively and different strains of group B streptococci formed pigment of different appearance, suggesting that group B streptococcal pigment is composed of several different substances.

Aerobiosis↗
PubMed2006

Clinical, dermoscopy and histological correlation study of melanotic pigmentations in excision scars of melanocytic tumours.

BACKGROUND: Melanotic pigmentations in scars consecutive to the excision of melanocytic tumours can be secondary to a reactive phenomenon related to the scar tissue or to a recurrence of the melanocytic lesion excised in the first case. Recurrent naevi may sometimes adopt unusual features that make them difficult to differentiate from a melanoma. OBJECTIVES: To describe the clinical, dermoscopic and histological features of melanotic pigmentations in scars consecutive to the excision of melanocytic tumours, and to correlate the histological diagnosis with the dermoscopic features. METHODS: This was a prospective cohort study using macrophotography, dermoscopy and histopathological study. Ninety-five melanotic pigmentations (77 patients) in scars secondary to the excision of melanocytic tumours were prospectively collected in the Department of Dermatology at the Instituto Valenciano de Oncología in Valencia, Spain. Histopathological study was performed in 57 scars. RESULTS: Thirteen dermoscopic structures were identified. Four criteria allowed a differentiation between reactive and specific melanocytic pigmentations. Presence of globules and presence of heterogeneous pigmentation were features associated with specific melanocytic pigmentations (P < 0.0001). Presence of a regular network and presence of streaks were more frequently found in reactive pigmentations (P = 0.023 and 0.026, respectively). CONCLUSIONS: Dermoscopic examination of melanotic pigmentations in excision scars of melanocytic tumours provides useful information about the origin of that pigmentation. Based on such information, recurrent naevi can be differentiated from reactive pigmentations in most cases. Excision and histopathological diagnosis continue to be imperative in some cases of recurrent naevi with atypical clinical features.

Cicatrix↗
PubMed1990

Dopamine induces light-adaptive retinomotor movements in bullfrog cones via D2 receptors and in retinal pigment epithelium via D1 receptors.

In the eyes of lower vertebrates, retinal photoreceptors and melanin pigment granules of the retinal pigment epithelium (RPE) exhibit characteristic retinomotor movements in response to changes in ambient illumination and to signals from an endogenous circadian clock. We previously reported that 3,4-dihydroxyphenylethylamine (dopamine) mimicked the effect of light on these movements in photo-receptors and RPE cells of green sunfish, Lepomis cyanellus, by interacting with D2 dopaminergic receptors. Here, we report that dopamine also mimics the effect of light on cone and RPE retinomotor movements in bullfrogs, Rana catesbeiana, i.e., dopamine induces cone contraction and RPE pigment dispersion. Dopamine induced cone contraction in isolated dark-adapted bullfrog retinas incubated in constant darkness in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). This effect of dopamine was inhibited by a D2 but not a D1 antagonist and mimicked by a D2 but not a D1 agonist. These results suggest that induction of cone contraction by dopamine is mediated by D2 dopaminergic receptors and that cone adenylate cyclase activity is inhibited. Thus, dopamine acts via the same type of receptor in both bullfrog and green sunfish retinas to induce cone contraction. In contrast, dopamine influences RPE retinomotor movement via different receptors in fish and bullfrog. Dopamine induced light-adaptive pigment dispersion in isolated dark-adapted bullfrog RPE-eyecups incubated in constant darkness in normal Ringer's solution. Because the retina was not present, these experiments demonstrate a direct effect of dopamine on bullfrog RPE. This effect of dopamine on bullfrog RPE was inhibited by a D1 but not a D2 antagonist and mimicked by a D1 but not a D2 agonist. Furthermore, agents that increase the concentration of intracellular cyclic AMP also induced pigment dispersion in dark-adapted bullfrog RPE-eyecups incubated in the dark. These results suggest that dopamine induces pigment dispersion in bullfrog RPE via D1 dopaminergic receptors. Thus, dopamine acts via different receptors on bullfrog (D1) versus green sunfish (D2) RPE to induce pigment dispersion. In addition, inhibitor studies indicate that pigment dispersion is actin dependent in teleost but not in bullfrog RPE. Dopamine-induced pigment dispersion was inhibited by cytochalasin D in isolated RPE sheets of green sunfish but not in RPE-eyecups of bullfrogs. Together, these observations indicate that dopamine mimics the effect of light on cone and RPE retinomotor movements in both fish and bullfrogs. However, in the RPE, different receptors mediate the effect of dopamine, and different cytoskeletal mechanisms are used to affect pigment transport.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed2004

Non-invasive measurements of skin pigmentation in situ.

Objective in situ measurements of skin pigmentation are needed for accurate documentation of pigmentation disorders, in studies of constitutive and induced skin pigmentation, for testing of the efficacy of pro-pigmentation or de-pigmentation agents, etc. Non-invasive instrumental measurements of skin pigmentation have been used for many decades. All are based on the ability of melanin to attenuate light. However, hemoglobin in dermal capillaries also attenuates light and needs to be accounted for when pigmentation is assessed. The methods under consideration include: (a) single point measurements, in which light reflected from a defined skin area is collected and a pigment index is calculated representing the average pigmentation over the examined area, and (b) imaging methods that attempt to generate a concentration distribution map of melanin pigment for the skin area being imaged. In this article, we describe the potentials and the limitations of the different approaches to both single point and imaging methods.

Dermoscopy↗
PubMed1976

The cyclopentolate provocative test in suspected or untreated open-angle glaucoma. III. The significane of pigment for the result of the cyclopentolate provocative test in suspected or untreated open-angle glaucoma.

Significant elevations of IOP, i. e. responses, occurred in eyes with suspected or untreated open-angle glaucoma during the mydriasis test with 1% cyclopentolate (CPT). The possible role of pigment in the IOP elevations seen in the responders was studied. Pigment was liberated in the aqueous, sometimes very profusely, in 88 (31.9%) of 276 eyes during CPT. The maximal IOP elevations, ad 20 mmHg, were seen in just these eyes. They were eyes with capsular or pigmentary glaucoma or eyes in which exceptionally heavy pigment was demonstrated in the chamber angle for other reasons. There was a statistically significant correlation between pigment liberation and IOP elevation during CPT. Evidently profuse pigment liberation may have caused transient blocking of the trabecular meshwork, obstruction of aqueous outflow and elevation of IOP. Liberation of pigment in the aqueous during CPT was statistically highly significantly more profuse in eyes with pseudoexfoliation than in eyes without pseudoexfoliation. An equally significant correlation with demonstrated between the grade of chamber angle pigmentation and the degree of pigment liberation during CPT. The significance of pigment for IOP elevation was seen also in the statistically highly significantly more profuse pigmentation of the chamber angle in the responder than in the non-responder eyes.

Aqueous Humor↗
PubMed1977

The effect of different nitrogen sources on pigment production and sporulation of Monascus species in submerged, shaken culture.

Thirty-nine strains from the genus Monascus were cultivated aerobically to study the relation between nitrogen nutrition and sporulation and pigment production. The effects of yeast extract, nitrate, ammonium, and ammonium nitrate have been compared. During cultivation the pHs of the different media are not the same, resulting in the formation of different coloured pigments. When the source of nitrogen is yeast extract or nitrate the pH is around 6.5 and red pigments are formed, whereas with ammonium or ammonium nitrate the pH is around 2.5 and the pigments are orange. It is proposed that only the orange pigments, monascorubrin and rubropunctatin, are produced biosynthetically and that the other pigments are formed from these by chemical transformations depending on the cultural conditions. The presence of organic nitrogen is optimal for growth and unfavourable for pigment production. Reduced growth and best pigment formation occurs with the three other nitrogen sources. Nitrate stimulates conidiation and sexual reproduction, while ammonium is inhibitory. Pigment production is better when conidiation is reduced. A mechanism is proposed for the control of sporulation and pigment production.

Ascomycota↗
PubMed1991

Generation of pigmented stripes in albino mice by retroviral marking of neural crest melanoblasts.

The pigment cells of the skin are derived from melanoblasts which originate in the neural crest. The dorsoventral migration of melanoblasts has been visualized in pigment stripes seen in aggregation chimeras, and the width of these bands has suggested that the entire pigmentation of the coat is derived from a small number of founder cells. We have generated mosaic mice by marking single melanoblasts in utero to gain information on the clonal history of pigment-forming cells. A retroviral vector carrying the human tyrosinase gene was constructed and microinjected into neurulating albino mouse embryos. Albino mice are devoid of pigmentation due to deficiency of tyrosinase. Thus, transduction of the wild-type gene into the otherwise normal melanoblasts should rescue the mutant phenotype, giving rise to patches of pigmentation, which correspond to the area colonized by the mitotic progeny of a marked clone. Mosaic animals derived from the injected embryos indeed showed pigmented bands with a width strikingly similar to the 'standard' stripes seen in aggregation chimeras. These results are consistent with the notion that the unit width bands seen in aggregation chimeras represent the clonal progeny of a single melanoblast and verify Mintz's (1967) conclusion that a few founder melanoblasts give rise to coat pigmentation. The pigment cells of the eye are of dual origin: the melanocytes in choroid and outer layer of the iris are derived from the neural crest and those in the pigment layer of the retina from the neuroepithelium of the optic cup. Marked clones in both lineages were observed in the eyes of many mosaic animals.

Animals↗
PubMed2003

Occlusable corneas in toadfishes: light transmission, movement and ultrastruture of pigment during light- and dark-adaptation.

The toadfishes Tetractenos hamiltoni and Torquigener pleurogramma (Tetraodontidae) possess occlusable yellow corneas. We examine the light transmission and location of the yellow/orange pigment throughout the cornea, the temporal properties of pigment migration and the ultrastructure of the pigmented processes during light- and dark-adaptation. Each species was dark-adapted during the day and light-adapted during the night and then exposed to either sun illumination or darkness for different lengths of time (0-70 min). Movement of corneal pigment could be induced in both species regardless of time of day or night. The pigment was able to migrate in a dorsal or ventral direction and changed from minimal to maximal pigmentation within 60 min. Three types of transmission curves were found with varying degrees of transmission in the 400-500 nm waveband, indicating that the pigment distribution is not uniform across the cornea; some areas of the cornea transmit near UV light, while others absorb blue light. The gradual change of the transmission characteristics in different areas of the cornea indicates the presence of different concentrations of a single type of pigment. Ultrastructural examination of the corneas showed that the layer containing the pigment is situated within the scleral cornea either surrounding (T. pleurogramma) or abutting (T. hamiltoni) an iridescent layer. Long sheet-like processes or chromatophores extending centrally from dorsal and ventral reservoirs are filled with pigment during the light-adapted state but empty in the dark-adapted state.

Adaptation, Ocular↗
PubMed1998

Presence of pigment in the ovine pineal gland during embryonic development.

Light- and electron-microscopic analyses were used to identify and describe the characteristic features of cells containing pigment in the ovine pineal gland during prenatal development. 72 ovine embryos (36 male, 36 female) ranging in age from 54 to 150 days were used for this study. Cells containing pigment granules were a constant feature in this gland. When samples from the different groups were inspected using the naked eye, the detection of pigment was of 61% in groups I (54 to 67 days of prenatal development) and II (71 to 92 days of prenatal development), 83% in group III (98 to 113 days of prenatal development) and 25% in group IV (118 to 150 days of prenatal development). The morphological features and histochemical properties of the pineal pigment enabled it to be identified as melanin. Several types of pigment granules were ultrastructurally distinguished; these varied in size, shape and location within pineal cell populations. The pigment granules were detected in pinealocytes, interstitial cells and pigmented cells. The largest amount and the widest variety of pigmented granules were found in pigmented cells. The presence of cells containing pigmented granules amongst the cell populations of the developing ovine pineal gland was analysed and compared with that of other mammalian species.

Animals↗
PubMedDate not supplied

Evidence for a pathway of distal screening pigment granules across the basement membrane of the crayfish photoreceptor.

The distal pigment cells of Orconectes limosus contain two layers of large electron lucent vacuoles that are separated by layers of small right-angled platelets adjacent to the crystalline cones. The crystalline cones of the dioptric apparatus of this species have evaginations into the distal pigment cell cytoplasm. In photoreceptors of Orconectes limosus and Procambarus clarkii a dark pigment accumulation site was detected just distal to the basement membrane at the edges of each retina. These pigment accumulations occurred independent of the state of light adaptation. Ultrastructurally the pigment granules at this accumulation site resemble distal screening pigment granules according to their size (up to 1.2 microns in diameter) and fibrous structure. Distal screening pigment granules were also found in tube-like cell processes or extracellularly within and proximal to the retinal basement membrane, indicating pigment transport to and across the basement membrane. Proximal to the basement membrane screening pigment granules were also observed disintegrated to a gravel-like electron dense material in widely branched cells. Evidence was found that an electron dense material, probably resulting from disintegrating screening pigment granules, was incorporated in the integument of the eyestalk. Four hours after injection of gold particles into the eye stalk distal to the retina they were detected inside and proximal to the retinal basement membrane.

Animals↗
PubMed1981

Biliary pigment and cholesterol calculi in patients with and without juxtapapillary duodenal diverticula.

The occurrence of pigment and cholesterol calculi was studied in 45 patients with concrements in the gallbladder but no calculi in the common or intrahepatic bile ducts. Twenty-one of the patients had juxtapapillary duodenal diverticula diagnosed by duodenoscopy. Twenty-four patients had no diverticula. The classification of the calculi as pigment stones or cholesterol stones was based on quantitative determination of the cholesterol contents. Calculi with a cholesterol content of less than 25% were classified as pigment stones; calculi with a cholesterol content of more than 25% were classified as cholesterol stones. All pigment stones had a cholesterol content of less than 20%. With the exception of four patients the cholesterol content was over 70% in all cholesterol stones. Twelve of the 21 patients with were classified as pigment stones; calculi with a cholesterol content of more than 25% were classified as cholesterol stones. All pigment stones had a cholesterol content of less than 20%. With the exception of four patients the cholesterol content was over 70% in all cholesterol stones. Twelve of the 21 patients with were classified as pigment stones; calculi with a cholesterol content of more than 25% were classified as cholesterol stones. All pigment stones had a cholesterol content of less than 20%. With the exception of four patients the cholesterol content was over 70% in all cholesterol stones. Twelve of the 21 patients with diverticula had pigment stones, whereas only 1 of the 24 patients without diverticula had pigment calculi, a difference that was statistically significant (p less than 0.01).

Adult↗
PubMed1993

Melanins and lens pigments: a comparative study.

Based on previous findings that lens pigments and melanins share many physicochemical properties, human lens pigments and natural (hair) and synthetic melanins were submitted to oxidation with permanganate under strong acidic conditions. This procedure has been utilized for the characterization of melanins and results in the well defined products, thiazole-4,5-dicarboxylic acid (TDCA) and pyrrole-2,3,5-tricarboxylic acid (PTCA), which can be quantitated by high performance liquid chromatography (HPLC). PTCA is regarded as a marker of black eumelanins and was therefore a main component of synthetic DOPA-eumelanin and dark hair. Its identity was established by synthesis from 5-hydroxyindole-2-carboxylic acid. TDCA derives from pheomelanins and was therefore an important component of red hair and synthetic GSH-pheomelanin. TDCA was identified by its retention time relative to PTCA. The analysis of a series of cataract digests of increasing pigmentation (type I < type IV < type V) and a purified fraction of lens pigments (DE52 pigment) revealed the presence in these preparations of both PTCA and TDCA. The concentration of TDCA significantly increased with the degree of pigmentation of the digests and reached a maximum in the DE52 pigment. The TDCA/PTCA ratio was high in the lens preparations and comparable to that given by hair pheomelanin. These findings support that pheomelanin is an integral part of lens pigments. By comparing the yields of TDCA in GSH-pheomelanin and in the purified lens pigment, a 9% contribution of pheomelanin to the lens pigment was estimated.

Cataract↗