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At least 19 recordsLinked to original sources
PubMed1985

Ultrastructure of pigment in adrenocortical pigmented adenomas of Cushing's syndrome and in non-functioning pigmented nodules with respect to tissue steroid analyses.

Ultrastructural and morphometrical analysis of brown pigment in pigmented (black) and non-pigmented adrenocortical adenomas of Cushing's syndrome and non-functioning pigmented adrenocortical nodules was performed in reference to tissue concentrations and in vitro production of steroids by the adenoma tissue. Pigment in pigmented adenomas was of membrane-bound lysosomal nature, while that of pigmented nodules contained membrane-unbound droplets of lipoid character. The morphometrical study showed little difference among individual adenomas. There was no difference between pigmented and non-pigmented adenomas in the amount of production and tissue concentrations of steroids. The steroid concentrations in a pigmented nodule were lower than those in an adenoma of Cushing's syndrome, but not significantly. Discussion is focused on the difference of pigment of lysosomal nature and of lipoid peroxidation.

Adenoma↗
PubMed1983

Retinomotor pigment migration in the teleost retinal pigment epithelium. I. Roles for actin and microtubules in pigment granule transport and cone movement.

In lower vertebrates, retinal pigment epithelial (RPE) cells and photoreceptors undergo dramatic "retinomotor movements" in response to changes in light conditions. In the dark, RPE pigment granules aggregate to the (choroidal) base of the RPE cells, cones elongate, and rods contract. In the light, movements are reversed: pigment granules migrate out into the long apical projections of the RPE cells, cones contract, and rods elongate. In this report the time courses of dark-induced pigment aggregation and light-induced dispersion have been characterized (and compared to cone movements) in the blue stripe grunt, Haemulon sciurus. It was found that aggregation and dispersion occur at linear rates of 3.4-3.5 microns/min and that RPE movements are kinetically independent from cone movements induced by the same changes in light conditions. The roles of actin and microtubules in RPE and cone movements were also investigated by using the actin-inhibitors, cytochalasins-B and -D, and the microtubule inhibitor, colchicine. Light-induced pigment dispersion, as well as maintenance of the fully dispersed (light-adapted) position appear to require actin-dependent processes. Intraocularly injected cytochalasins-B and -D fully prevented pigment dispersion when administered to dark-adapted animals immediately prior to their exposure to light, and caused pigment aggregation to the RPE cell base when administered to fully light-adapted animals. Ultrastructural studies showed that actin filaments, which in untreated retinas were found closely associated with pigment granules and the plasma membrane, were disrupted after cytochalasin-B treatment. Both dispersive and aggregative pigment movements within the cell body appeared to require microtubule-dependent processes. Intraocularly injected colchicine disrupted microtubules and blocked pigment granule translocation in both directions in the cell body. A hypothetical model to explain pigment movements in response to changes in light conditions is proposed based on these observations as well as on data from the literature.

Actins↗
PubMed1990

[Pigmented spindle cell nevus and pigmented Spitz nevus--clinical and histopathological study on pigmented Spitz nevus, and its differentiation from early melanoma by fluorescence method and measurement of 5-S-CD level in the lesion].

On the basis of clinical and histopathological studies on 17 patients who had been diagnosed as having pigmented Spitz nevus (PSN), pigmented spindle cell nevus (PSCN) was surmised to be a type of pigmented Spitz nevus. In order to distinguish pigmented spindle cell nevus and pigmented Spitz nevus from early melanoma, 5 PSCN cases and 12 PSN cases were analyzed by the fine-needle aspiration fluorescence method, touch fluorescence method and measurement of the 5-S-CD level in the lesion. With the touch fluorescence method, fluorescent tumor cells were detected in one case of PSN. With the fine-needle aspiration fluorescence method, fluorescent tumor cells were detected in one PSCN case and 2 PSN cases. In comparison with fluorescent melanoma cells, the detected fluorescent tumor cells were smaller in size and number and resembled melanocytes. The 5-S-CD level in the lesion was 50 ng/mg or less in all cases, whereas the level in melanoma is known to be a high 100 ng/mg or more. In the final analysis, measurement of the 5-S-CD level in the lesion was concluded to have the greatest utility for differential diagnosis of pigmented spindle cell nevus and pigmented Spitz nevus from early melanoma.

Adolescent↗
PubMed1976

[Pigmented cysts. Pigmented epidermal cysts and pigmented trichilemmal cyst].

The clinical and histopathological picture of the pigmented epidermal cyst and the pigmented trichilemmcyst is illustrated by three case-reports. The pigment is melanin, which is located in the epithelium of the cyst-wall, the corneocytes of the lumen and in macrophages in the dermis. The clinical appearance of melanin pigmented cysts is blue due to the Tyndall-phenomenon.

Adult↗
PubMed1998

PEDF (pigment epithelium-derived factor) promotes increase and maturation of pigment granules in pigment epithelial cells in neonatal albino rat retinal cultures.

Pigment Epithelium-Derived Factor (PEDF), purified from human retinal pigment epithelial (RPE) cell culture medium, is a neurotrophic factor which potentiates the differentiation of human Y-79 retinoblastoma cells and increases the survival of cerebellar granule cells. To investigate the effects of PEDF on non-transformed retinal cells, we used primary cultures of neonatal albino rat retinas, where the three principal cell types of the retinal layers (neuronal, glial and epithelial) were all present and focussed our attention on RPE cells, which are of special relevance for retinal pathophysiology. PEDF had a dramatic effect on these cells. They showed a modified phenotype, with larger dimensions, higher cytoplasmic spreading, presence of phagocytic vacuoles, development of wide intercellular contacts, and increase and maturation of pigment granules. These results suggest that PEDF may have a role in regulating RPE cell differentiation.

Animals↗
PubMed2002

Preliminary approach to elucidate the role of pigment as a binding site for drugs and chemicals in anagen hair: differential uptake of 3H-haloperidol by pigment-producing compared to non-pigment-producing cell lines.

A striking difference was observed for cellular-bound drug in HaCaT and Sk-Mel-1 cells for a fixed drug exposure time of 72 h and varying 3H-haloperidol concentrations in the culture media. Drug uptake was dependent on drug concentration and linearly correlated for both the non-pigment- and the pigment-producing cells which however was different in magnitude. In an additional investigation the time course of drug uptake during 3H-haloperidol exposure (400 pmol/ml; 28 days) revealed increasing drug concentrations in the Sk-Mel-1 population, whereas drug concentrations in the keratinocytes reached a plateau within a short time period. In contrast to the HaCaT cells no tendency to saturation was observed for the pigment-producing cell line. At the end of the experiments 3H-haloperidol concentrations in Sk-Mel-1 were found to be approximately tenfold higher than in HaCaT.

Binding Sites↗
PubMed2001

Library of FT-Raman spectra of pigments, minerals, pigment media and varnishes, and supplement to existing library of Raman spectra of pigments with visible excitation.

Sixty pigments, minerals and media have been analysed by Fourier-transform Raman (FT-Raman) microscopy in order to assemble a database of reference FT-Raman spectra for scientists working at the Arts-Science interface. An earlier library of Raman spectra compiled using visible excitation has been extended by the addition of 22 further reference spectra obtained with 780.0, 647.1, 632.8 and/or 514.5 nm excitation. The relative merits of 1064 nm and visible excitation are discussed.

Databases, Factual↗
PubMed2001

Red pigment-concentrating hormone induces a calcium-mediated retraction of distal retinal pigments in the crayfish.

The octapeptide red pigment-concentrating hormone is capable of eliciting the aggregation of intracellular pigment granules in distal retinal pigment cells of isolated retinas of the crayfish Procambarus clarkii (Girard). The final level and the time course of pigment aggregation are dose dependent within a range of 10(-10) mol l(-1) to 10(-4) mol l(-1). The effect of red pigment-concentrating hormone is prevented by previous incubation with an anti- red pigment-concentrating hormone antibody; however, application of the antibody after the onset of the red pigment-concentrating hormone effect, does not prevent its full development. A similar effect to that elicited by red pigment-concentrating hormone is induced by the calcium ionophores ionomycin and A-23187. Red pigment-concentrating hormone evokes entry of 45Ca2+ to retinal cells. However, the red pigment-concentrating hormone-induced pigment aggregation persists in the presence of the calcium channel blocker verapamil and in Ca2+-free solutions. Caffeine and thapsigargin, known to release calcium from intracellular stores, elicit distal pigment aggregation, while ryanodine and dantrolene, blockers of intracellular calcium release, as well as the intracellular calcium chelator bapta-AM suppress the effect of red pigment-concentrating hormone. These results suggest that red pigment-concentrating hormone elicits distal retinal pigment aggregation by increasing intracellular calcium concentration, acting via a dual mechanism: (1) promoting calcium entry, and (2) releasing intracellular calcium.

Animals↗
PubMed1998

DNA damage in isolated rat hepatocytes exposed to C.I. pigment orange 5 and C.I. pigment yellow 12 by the alkaline comet assay.

The induction of DNA damage by commonly used printing ink pigments, C.I. pigment orange 5 (C.I. 12075) and C.I. pigment yellow 12 (C.I. 21090), was investigated in freshly isolated rat hepatocytes with the comet assay. C.I. pigment yellow 12 is a 3,3'-dichlorobenzidine-based diarylide pigment, and C.I. pigment orange 5 is a naphthol-azo pigment. The pigments are virtually insoluble in aqueous solutions, and they have not been tested extensively for toxicological effects. C.I. pigment orange 5 increased the levels of DNA damage at 5 microg/ml (P < 0.02) and C.I. pigment yellow 12 at 20 microg/ml (P < 0.002). The effect of incubation time (20, 40, and 80 min) of the same concentrations of the pigments was tested. The levels of DNA damage were increased up to 80 min. Both pigments produced DNA damage that was in the same range as the food carcinogen 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline. Our data indicate that both C.I. pigment orange 5 and C.I. pigment yellow 12 are genotoxic in hepatocytes with metabolizing capacities. However, further investigation of the metabolism and disposition are required for the evaluation of the safety of these pigments.

Alkalies↗
PubMed1996

Calcium-independent regulation of pigment granule aggregation and dispersion in teleost retinal pigment epithelial cells.

In the eyes of teleosts and amphibians, melanin pigment granules of the retinal pigment epithelium (RPE) migrate in response to changes in light conditions. In the light, pigment granules disperse into the cells' long apical projections, thereby shielding the rod photoreceptor outer segments and reducing their extent of bleach. In darkness, pigment granules aggregate towards the base of the RPE cells. In vitro, RPE pigment granule aggregation can be induced by application of nonderivatized cAMP, and pigment granule dispersion can be induced by cAMP washout. In previous studies based on RPE-retina co-cultures, extracellular calcium was found to influence pigment granule migration. To examine the role of calcium in regulation of RPE pigment granule migration in the absence of retinal influences, we have used isolated RPE sheets and dissociated, cultured RPE cells. Under these conditions depletion of extracellular or intracellular calcium ([Ca2+]o, [Ca2+]i) had no effect on RPE pigment granule aggregation or dispersion. Using the intracellular calcium dye fura-2 and a new dye, fura-pe3, to monitor calcium dynamics in isolated RPE cells, we found that [Ca2+]i did not change from basal levels when pigment granule aggregation was triggered by cAMP, or dispersion was triggered by cAMP washout. Also, no change in [Ca2+]i was detected when dispersion was triggered by cAMP washout in the presence of 10 microM dopamine, a treatment previously shown to enhance dispersion. In addition, elevation of [Ca2+]i by addition of ionomycin neither triggered pigment movements, nor interfered with pigment granule motility elicited by cAMP addition or washout. Since other studies have indicated that actin plays a role in both pigment granule dispersion and aggregation in RPE, our findings suggest that RPE pigment granule migration depends on an actin-based motility system that is not directly regulated by calcium.

Animals↗
PubMed1992

Primary structures of chicken cone visual pigments: vertebrate rhodopsins have evolved out of cone visual pigments.

The chicken retina contains rhodopsin (a rod visual pigment) and four kinds of cone visual pigments. The primary structures of chicken red (iodopsin) and rhodopsin have been determined previously. Here we report isolation of three cDNA clones encoding additional pigments from a chicken retinal cDNA library. Based on the partial amino acid sequences of the purified chicken visual pigments together with their biochemical and spectral properties, we have identified these clones as encoding the chicken green, blue, and violet visual pigments. Chicken violet was very similar to human blue not only in absorption maximum (chicken violet, 415 nm; human blue, 419 nm) but also in amino acid sequence (80.6% identical). Interestingly, chicken green was more similar (71-75.1%) than any other known cone pigment (42.0-53.7%) to vertebrate rhodopsins. The fourth additional cone pigment, chicken blue, had relatively low similarity (39.3-54.6%) in amino acid sequence to those of the other vertebrate visual pigments. A phylogenetic tree of vertebrate visual pigments constructed on the basis of amino acid identity indicated that an ancestral visual pigment evolved first into four groups (groups L, S, M1, and M2), each of which includes one of the chicken cone pigments, and that group Rh including vertebrate rhodopsins diverged from group M2 later. Thus, it is suggested that the gene for scotopic vision (rhodopsin) has evolved out of that for photopic vision (cone pigments). The divergence of rhodopsin from cone pigments was accompanied by an increase in negative net charge of the pigment.

Amino Acid Sequence↗
PubMed1984

The macular pigment. I. Absorbance spectra, localization, and discrimination from other yellow pigments in primate retinas.

The nonbleaching yellow pigments of the primate fovea were studied by microspectrophotometry (MSP). Retinas fixed with glutaraldehyde/paraformaldehyde mixtures retained yellow pigments with absorbance spectra very similar to those recorded by MSP in fresh retinas. This allowed the authors to prepare retinal sections for localization of the pigments. The spectrum of the macular pigment in fixed tissue is shifted slightly (about 6 nm) toward longer wavelengths, with maximum absorbance at 460 nm. Two short-wavelength yellow pigments also have been identified, with absorbance maxima at 410 nm ( P410 ) and 435 nm ( P435 ), respectively. All three yellow pigments are present in the fovea. The short-wavelength pigments are detected more easily outside the central foveal region because the macular pigment does not obscure them there. They are especially apparent when the MSP beam is confined to the outer nuclear layer or the inner segment layer of retinal sections. The macular pigment is most dense in the fiber layers (receptor axon layer and inner plexiform layer); its density declines markedly with retinal eccentricity. The maximal absorbance of P410 and P435 is usually lower than that of the macular pigment in the central fovea, but their densities and relative proportions change more gradually with eccentricity. Consequently, their maximal absorbance is higher than that of the macular pigment outside the foveal center. The P410 and P435 pigments may be two different oxidation states of one or more respiratory hemoproteins. Commonly used procedures for estimating the absorbance spectrum of the macular pigment by comparing the foveal center with a parafoveal region may be influenced by the amounts and the oxidation states of the short-wavelength pigments in the living eye.

Animals↗
PubMed1993

Iron-induced accumulation of lipofuscin-like fluorescent pigment in the retinal pigment epithelium.

PURPOSE: One of the most prominent changes that occurs in the retinal pigment epithelium during senescence is the progressive accumulation of the autofluorescent pigment lipofuscin. Experiments were conducted to evaluate the role of nonenzymatic oxidation of photoreceptor outer segments in retinal pigment epithelium lipofuscin formation. METHODS: Albino Fischer rats were given intravitreal injections of ferrous sulfate, a catalyst that promotes nonenzymatic lipid oxidation. At 2 hours, 24 hours, and 7 days after ferrous sulfate administration, the retinas were examined with fluorescence microscopy to assess the formation of fluorescent products. At these same time intervals, organic solvent extracts of the retinas and retinal pigment epithelium-choroid complexes were prepared. The extracts were analyzed with thin layer chromatography to assay for the presence of soluble fluorophores. The ultrastructural appearances of the retinas were examined at the same time points. RESULTS: At both 2 hours and 24 hours after the ferrous sulfate treatment, the photoreceptor outer segments displayed a yellow-green fluorescence emission that was not present in untreated eyes. Associated with this in situ fluorescence were a number of blue-green emitting fluorophores in organic solvent extracts that did not correspond to any of the fluorophores extracted from the retinal pigment epithelium of old animals. One week after the ferrous sulfate treatment, the photoreceptor cells had degenerated and the retinal pigment epithelium contained large amounts of an autofluorescent pigment with a golden-yellow emission typical of lipofuscin. The iron-induced fluorophores could not be extracted from this pigment into either chloroform or dichloromethane. CONCLUSIONS: The initial fluorophores that were formed as a result of nonenzymatic oxidation of outer segment components did not appear to be the same as those responsible for retinal pigment epithelium lipofuscin fluorescence. However, after the oxidized outer segments were phagocytosed by the retinal pigment epithelium, the latter cells became filled with a yellow-emitting fluorescent pigment that was similar in its fluorescence properties to lipofuscin. These observations suggest that lipofuscin fluorophores are not direct products of nonenzymatic lipid oxidation. However, some of these oxidation products may be modified after uptake by the retinal pigment epithelium to form insoluble lipofuscin fluorophores.

Animals↗
PubMed2026

Metabolomic and structural signatures of pigmented and non-pigmented Himalayan rice landraces.

BACKGROUND: This study investigated the anti-oxidant properties, starch composition, pasting behavior, structural properties, textural properties and non-targeted metabolomic profiles of pigmented and non-pigmented rice landraces as potential next-generation functional food ingredients. RESULTS: Pigmented rice demonstrated 1.34 times more anti-oxidant activity as compared to non-pigmented rice. Pigmented landraces showcased superior nutritional and functional attributes, including higher total dietary fiber and starch content. Fourier-transform infrared (FTIR) analysis revealed distinct molecular signatures with enhanced peak transmittance, while X-ray diffraction (XRD) indicated greater crystallinity ranging from 36-44.3% in pigmented rice compared with 30-40% in non-pigmented rice, suggesting improved digestibility and processing versatility. Pigmented rice recorded less amylose content hence tended to possess increased adhesiveness values whereas non-pigmented rice revealed greater amylose content hence was coupled with greater hardness values. Field-emission scanning electron microscopy (FE-SEM) images revealed that pigmented rice had densely packed and polygonal starch granules whereas non-pigmented rice had loosely packed starch granules with intergranular voids. Untargeted gas chromatography-mass spectrometry (GC-MS) profiling identified 84 metabolites, including unique compounds such as 3,3-dimethylbutanol and ethanoic acid, along with shared metabolites such as sucrose and linoleic acid, highlighting notable biochemical diversity. Multivariate statistical analyses using principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway mapping further differentiated the metabolomic landscapes, with variable importance in the projection (VIP) scores identifying key bioactive contributors. CONCLUSION: Pigmented rice landraces exhibited significant functional and nutritional advantages, making them promising candidates for functional food development and nutritional improvement programs. These findings support their potential role in advancing sustainable and health-oriented food systems. &#xa9; 2026 Society of Chemical Industry.

Oryza↗
PubMed2001

Development of pigment cells in the brain of ascidian tadpole larvae: insights into the origins of vertebrate pigment cells.

In vertebrates, melanins produced in specialized pigment cells are required for visual acuity, camouflage, sexual display and protection from ultra violet (UV) radiation. There are three pigment cell types that are classified based on their distinct embryonic origins. Retinal pigment epithelium (RPE) cells originate from the outer layer of the optic cup. Pigment cells of the pineal organ are formed from the developing diencephalon. Melanocytes are derived from the neural crest unique to vertebrate embryos. Some of these pigment cells also play roles that are independent of the activity of tyrosinase, the key melanogenesis enzyme, or melanin: production of substrate(s) for catecholamine synthesis, maintenance of endolymph composition in the cochlea, maintenance of photoreceptor cells in the retina and retinoid metabolism essential for the visual cycle. To deduce the evolutionary origins of vertebrate pigment cells and a possible archetypal genetic circuitry, which may have been modified and utilized to generate multiple pigment cell types, comparison of developmental mechanisms of pigment cells between vertebrates and closely related invertebrate ascidians are proposed to provide useful information. The tadpole-type larva of ascidians possesses two melanin-containing pigment cells, termed the otolith and ocellus pigment cells, in the brain that are believed to be required for photo- and geotactic responses during swimming. In this review, current knowledge on the development of the two ascidian pigment cells is summarized, i.e. complete cell lineage, structure and expression of genes encoding two melanogenesis enzymes, and molecular developmental mechanisms involving BMP-CHORDIN antagonism, and possible evolutionary relationships between ascidian and vertebrate pigment cells are discussed.

Animals↗
PubMed1987

Pigment gallstones form as a composite of bacterial microcolonies and pigment solids.

Although previous studies have suggested that bacteria may contribute to pigment gallstone formation, the current experiments provide evidence that bacteria have a central role in this process. The studies included scanning electron microscopy (SEM) of gallstones, measurements of bacterial adherence to gallstones in vitro, and determination of glycocalyx elaboration by biliary bacteria. Gallstones from 85 patients were studied under SEM. Twenty-five (78%) of 32 pigment stones had evidence of bacterial microcolonies throughout the interior of the stones. Bacteria were absent from the interior of all 35 cholesterol stones studied. Composite stones (stones with separate pigment and cholesterol portions) showed evidence of bacteria within the pigment portions in 14 (78%) of 18 cases. Biliary bacteria adhered to the surface of pigment gallstones in vitro in 35 (90%) of 39 cases, compared with three (8%) of 39 cholesterol stones. Glycocalyx was elaborated by bacteria isolated from nine (82%) of 11 patients with either pigment or composite gallstones. One (33%) of three bacterial species from patients with cholesterol gallstone disease produced glycocalyx. These studies indicate that most pigment gallstones obtained from patients in Western cultures form as a composite of bacteria, bacterial glycocalyx, and pigment solids. Bacteria were found in the majority of black as well as brown pigment stones. These findings serve as the basis of a new theory of pigment stone formation in which bacteria and glycocalyx are postulated to be responsible for the precipitation and subsequent agglomeration of bilirubin pigment. These results also suggest that sepsis is more common in pigment gallstone disease because the stones can serve as a sanctuary for bacteria.

Adult↗