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PubMed2005

Porocarcinoma arising in pigmented hidroacanthoma simplex.

Hidroacanthoma simplex (HAS) is a rare benign tumor that is also known as intraepidermal poroma. While there have been a few reports of HAS with malignant transformation (porocarcinoma), we report an unusual case of porocarcinoma, arising in a pigmented HAS, the latter also showing secondary amyloid deposits. An 80-year-old Japanese man presented with a cutaneous tumor on his left buttock, which had first been noticed in his childhood. The tumor consisted of flat pigmented plaque and a depigmented papule with erosion. Histologic analysis revealed many pigmented and well-defined nests within the epidermis of the flat pigmented portion. The nests were composed of cuboidal to oval and occasionally elongated, bland, basaloid cells with numerous melanin granules. In addition, there were infrequently ductal structures and small clusters of sebocytes, and abundant amyloid deposits in the upper dermis. These findings were consistent with pigmented HAS with amyloid deposition. In the depigmented portion, markedly atypical cells with occasional ductal structures and intracytoplasmic lumina extended throughout the entire thickness of the epidermis, with minimal invasion of the dermis. We considered this portion of the tumor to be a porocarcinoma. Since the two portions of the tumor were continuous, we made a final diagnosis of porocarcinoma arising in pre-existing pigmented HAS with amyloid deposition.

Acanthoma↗
PubMed1999

Xanthophyll cycle pigment localization and dynamics during exposure to low temperatures and light stress in vinca major

The distribution of xanthophyll cycle pigments (violaxanthin plus antheraxanthin plus zeaxanthin [VAZ]) among photosynthetic pigment-protein complexes was examined in Vinca major before, during, and subsequent to a photoinhibitory treatment at low temperature. Four pigment-protein complexes were isolated: the core of photosystem (PS) II, the major light-harvesting complex (LHC) protein of PSII (LHCII), the minor light-harvesting proteins (CPs) of PSII (CP29, CP26, and CP24), and PSI with its LHC proteins (PSI-LHCI). In isolated thylakoids 80% of VAZ was bound to protein independently of the de-epoxidation state and was found in all complexes. Plants grown outside in natural sunlight had higher levels of VAZ (expressed per chlorophyll), compared with plants grown in low light in the laboratory, and the additional VAZ was mainly bound to the major LHCII complex, apparently in an acid-labile site. The extent of de-epoxidation of VAZ in high light and the rate of reconversion of Z plus A to V following 2.5 h of recovery were greatest in the free-pigment fraction and varied among the pigment-protein complexes. Photoinhibition caused increases in VAZ, particularly in low-light-acclimated leaves. The data suggest that the photoinhibitory treatment caused an enrichment in VAZ bound to the minor CPs caused by de novo synthesis of the pigments and/or a redistribution of VAZ from the major LHCII complex.

Journal Article↗
PubMed1977

Pigmentation and Antibacterial Activity of Fast Neutron- and X-Ray-induced Strains of Monascus purpureus Went.

Seven new strains of Monascus purpureus Went were induced by neutron and x-ray irradiation. The quantity and quality of pigments produced by these strains differed. Strains N4S and N11S produced twice as much pigment as normal, while another strain, N14S, was albino. An unknown orange pigment was found in young colonies of the N11S strain. This orange pigment reacted with alcohols and malt extract medium to form red pigments. Strains N4S, N11S, X2P, and wild type inhibited the growth of certain bacteria, especially the Bacillus species. Strain N11S had more antibacterial activity than wild type. A major active compound was isolated with an ultraviolet absorption spectrum that was related to those of the red pigments found in this fungus. The active compound(s) was named monascidin.

Journal Article↗
PubMed1996

Tattoo pigment mimicking metastatic malignant melanoma.

BACKGROUND: The benefits of elective lymph node dissection (ELND) in the treatment of melanoma remain controversial, however, it may be beneficial in some patients. Tattoo pigment from decorative tattoos may migrate to the regional lymph nodes. In patients who develop malignant melanoma and who have been tattooed, this pigment may clinically mimic metastatic disease. OBJECTIVE: We wish to alert clinicians that pigment from tattoos may migrate to the regional lymph nodes. In the unusual instance of a tattooed patient who develops malignant melanoma, when undergoing ELND, surgeons should rely on histologic confirmation of metastatic disease before altering operative plans. METHODS: ELND for malignant melanoma, in a patient with a history of decorative tattoos that had been removed by dermabrasion, was performed. Black lymph nodes that clinically resembled metastatic disease were identified. Subsequent histologic examination revealed normal lymph node architecture with a heavy collection of black pigment. Mass spectrophotometry showed this pigment to be consistent with tattoo dye. RESULTS: A patient who had undergone dermabrasion for removal of decorative tattoos developed malignant melanoma in the same extremity. Clinically suspicious black lymph nodes were identified during ELND. Histologic examination did not reveal metastatic disease. Additional therapy was not considered intra- or postoperatively even though the clinical suspicion of metastatic disease was high. The patient was not subjected to any unnecessary emotional or physical distress pending histologic confirmation. CONCLUSIONS: Tattoo pigment in the lymph nodes may clinically mimic metastatic melanoma. Histologic confirmation of metastatic disease should always be obtained before additional therapy is considered.

Adult↗
PubMed2004

Pigmented Bowen's disease mimicking cutaneous melanoma: clinical and dermoscopic aspects.

BACKGROUND: Pigmented Bowen's disease (BD) (squamous cell carcinoma in situ) has been rarely described among white patients. OBJECTIVE AND METHODS: We report the case of a 48-year-old white male presenting a lesion of pigmented BD on his left thigh, clinically mimicking a superficial spreading melanoma. RESULTS: Naked-eye physical examination revealed a single 1.8 x 1.5 cm, hyperpigmented plaque with a rough surface, which appeared irregularly shaped and sharply demarcated. The assessment of this uncommon tumor by means of dermoscopy, never reported in literature before, was performed. According to standardized terminology, none among the well-established dermoscopic criteria useful to discriminate between melanocytic and nonmelanocytic origin was detected within the lesion. A reticular pigmentation simulated remnants of atypical pigment network, being of uncertain diagnostic value in the preoperative classification of the lesion. Other recognized patterns were irregular, brown globular structures and wide regression-like areas. None of the features diagnostic for pigmented basal cell carcinoma was found as well. CONCLUSION: The correct classification of nonmelanocytic origin of the lesion was therefore achieved only at histologic examination, after the complete surgical excision. In spite of its rarity, pigmented BD should be included among those lesions, which may simulate cutaneous melanoma. According to criteria validated by literature, dermoscopy failed to improve a preoperative classification of this peculiar skin tumor.

Bowen's Disease↗
PubMed1995

Growth and pigmentation in genetically related Cloudman S91 melanoma cell lines treated with 3-isobutyl-1-methyl-xanthine and beta-melanocyte-stimulating hormone.

4 clonal sublines of Cloudman S91 melanoma cells, S91/mel, S91/I3, S91/6 and S91/amel, were evaluated for changes in growth, pigment content and plating efficiency during and after treatment with a cyclic-AMP phosphodiesterase inhibitor-melanin-stimulating agent, 3-isobutyl-1-methyl-xanthine (IBMX) plus beta-melanocyte stimulating hormone (beta-MSH) or IBMX alone. After combined treatment, increases in melanin content on day 3 were 48, 27, 11, and 2 pg/cell in the four cell lines respectively. In each case IBMX alone was less effective than IBMX plus beta-MSH. Doubling time increased and plating efficiency decreased with increased melanization. The increases in doubling time and decreases in plating efficiency were cell line dependent. The greatest rate of increase in doubling time and decrease in plating efficiency as a function of melanin content were seen in S91/amel, which produced the least pigment. The lowest rates of increase/decrease were seen in S91/mel, which produced the most pigment. Melanin pigment induced in the cells was classified as eumelanin by EPR determination. The differential response to induction of pigmentation makes these cell lines suitable models for comparative studies on the role of melanin in pigment cell biology.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Phosphorylated mixed isomers of L-dopa increase melanin content in skins of Skh-2 pigmented hairless mice.

Dopa phosphates, a new class of compounds, contain phosphate-ester linkages at the 3- and/or 4- positions of the phenylalanine ring of L-dopa. Dopa phosphates have been shown to increase pigment production in the epidermis of hairless mice. Groups of Skh-2 pigmented hairless mice were treated topically with various concentrations of dopa phosphates daily for five weeks. Half of each group received suberythemal UVB radiation three times weekly for four weeks from a bank of filtered FS20 lamps. UVB and dopa phosphates alone each caused a modest increase in epidermal pigmentation. However, treatment of mice with dopa phosphates plus UVB radiation resulted in a marked increase in pigmentation, greater than with either treatment alone. The optimal concentration of dopa phosphates was 0.01% (100 micrograms/ml Tris-glycerol buffer) whether or not they were applied in conjunction with UVB radiation. Histological analyses revealed that dopa phosphates and UVB radiation each caused an increase in the number of pigmented melanocytes in the epidermis. Control groups treated with Tris-glycerol buffer alone, or buffer containing L-phenylalanine or L-dopa showed no significant changes in pigmentation. Our results indicate that dopa phosphates stimulate the production of melanin and affect the development and distribution of melanocytes in the skin of Skh-2 mice. By these criteria, dopa phosphates and UVB act in a similar manner to increase melanin content in the skin. The processes may be related to those recently observed in cultured mouse melanoma cells where dopa phosphates are incorporated into melanin, presumably following enzymatic hydrolysis by cellular phosphatases with the resultant production of L-dopa and inorganic phosphate.

Animals↗
PubMedDate not supplied

Antioxidant enzymatic systems in pigment tissue of amphibia.

Superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities in pigmented and unpigmented liver tissues of frog and albino rat, respectively, were studied. Our results show that pigmented tissue is lacking in manganese superoxide dismutase activity and that the main enzymatic activity utilized in the cytosol by pigmented cells to reduce the hydrogen peroxide to water is represented by catalase; on the contrary, for the same reaction, the cells of albino rat liver primarily utilize the glutathione peroxidase activity. Both a low glutathione peroxidase activity and a low glutathione reductase activity were found in pigmented tissue of frog liver when compared with unpigmented tissue of rat liver. In light of our results, we also report a hypothetical interrelationship between melanin and reduced glutathione: We believe that in pigmented cells the melanin could act as a reducing physiological agent replacing the glutathione in the reduction of hydrogen peroxide. This reducing action of melanin could cause a diminished need for GSH and therefore could provoke the low glutathione peroxidase and reductase activities in pigmented tissue.

Animals↗
PubMed1992

Extracellular matrix constituents and pigment cell expression in primary cell culture.

Three types of pigment cells were isolated and cultured from larval Rana pipiens, and their attachment, maintenance, and proliferation were examined in the presence of extracellular matrix constituents (ECMs) in primary cell culture. The initial profile of pigment cell types present on day 2 of culture reflects the relative attachment of the cells to the dishes. Changes in the numbers of cells present after day 2 reflects the influence of factors present in the culture media on the maintenance, proliferation, or detachment of each type of pigment cell. Fetal bovine serum (FBS) promoted melanophore expression, but inhibited iridophore expression. FBS had no effect on xanthophores. In contrast, ventral skin conditioned medium (VCM), which contains melanization inhibiting factor, strongly stimulated iridophore expression, while it markedly inhibited melanophore expression. VCM had little effect on xanthophores. Of the ECMs tested, collagen type I had no effect on pigment cells. Fibronectin slightly inhibited melanophore expression, while it moderately stimulated iridophores and xanthophores. The stimulatory effect of fibronectin was not as strong as that of FBS or VCM. Laminin was also tested; however, it did not allow pigment cells to attach to the dishes, at least under the culture conditions utilized. The results of these experiments are discussed in terms of the general mechanisms of pigment pattern formation.

Animals↗
PubMed1972

Production of diagnostic pigment by phenoloxidase activity of cryptococcus neoformans.

Cryptococcus neoformans produces brown pigmented colonies when grown on agar media made from an extract of potatoes and carrots, broad beans (Vicia faba), or Guizotia abyssinica seeds. Since other yeasts do not produce the pigment, these media are useful as differential isolation media for C. neoformans. Similar specific pigment was produced by C. neoformans on chemically defined agar media which contained six different substrates of phenoloxidase (o-diphenol: oxygen oxidoreductase EC 1.10.3.1) an enzyme which catalyses the oxidation of o-diphenols to melanin. Substrates were incorporated singly into the media and included L-3, 4-dihydroxyphenylalanine (L-DOPA), chlorogenic acid, protocatechuic acid, catechol, norepinephrine, and 3-hydroxytyramine hydrochloride (dopamine). No pigment was produced on media without substrate. Phenoloxidase activity in (NH(4))(2)SO(4) precipitates of C. neoformans cell-free extract was assayed by measuring increases in absorbance at 480 nm produced in solutions of L-DOPA. This reaction showed oxygen uptake and was effectively inhibited by copper chelators, but not by catalase. The enzyme also oxidized the five other substrates which induced pigment formation. Electron micrographs of cells incubated in L-DOPA showed deposition of the pigment in the cell wall.

Agar↗
PubMed1986

Fluorescein angiography of the iris in anterior segment pigment dispersal syndrome.

The results are presented of fluorescein angiography of the iris in 11 patients with anterior segment pigment dispersal syndrome. These show a general hypovascularity of the iris with fine neovascularisation at the pupil margin and the peripupillary area. Hypoplasia of the iris stroma was also present in many cases. When the condition was virtually unilateral, the vascular changes were present though less marked in the relatively unaffected eye. It is postulated that the anterior segment pigment dispersal syndrome is secondary to a congenital mesodermal deficiency of the iris stroma with hypovascularity of the iris, which forms a poor support tissue for the pigment epithelium of the iris, resulting in shedding of pigment granules particularly in the region of the attachment of the dilator muscle to the pigment epithelium. The condition may be hereditary. Because of the hypovascularity the mesodermal hypoplasia may be progressive, but pigment release may diminish in later life with treatment, with consequent diminution of pupil activity.

Cell Count↗
PubMed2003

Pigment cells: a model for the study of organelle transport.

Eukaryotic organisms rely on intracellular transport to position organelles and other components within their cells. Pigment cells provide an excellent model to study organelle transport as they specialize in the translocation of pigment granules in response to defined chemical signals. Pigment cells of lower vertebrates have traditionally been used as a model for these studies because these cells transport pigment organelles in a highly coordinated fashion, are easily cultured and transfected, are ideal for microsurgery, and are good for biochemical experiments, including in vitro analysis of organelle motility. Many important properties of organelle transport, for example, the requirement of two cytoskeletal filaments (actin and microtubules), the motor proteins involved, and the mechanisms of their regulation and interactions, have been studied using pigment cells of lower vertebrates. Genetic studies of mouse melanocytes allowed the discovery of essential elements involved in organelle transport including the myosin-Va motor and its receptor and adaptor molecules on the organelle surface. Future studies of pigment cells will contribute to our understanding of issues such as the cooperation among multiple motor proteins and the mechanisms of regulation of microtubule motors.

Animals↗
PubMed1995

Studies on age pigments evolving into a new theory of biological aging.

A variety of age pigment-like fluorophores have been recognized, identified and investigated during the past three decades. They are mainly the end-products of various side-reactions of essential biological processes. Among these, the lipid peroxidation-related fluorophores formed via aldehyde-protein crosslinking are of general importance. Fluorescent advanced glycation end-products formed during glycation/Maillard reactions, are oxygen independent, carbohydrate-associated age pigment-like substances. Age pigments, particularly those identified in retinal pigment epithelium, represent another type of age pigment that originates from polyenic biomolecules, including retinoids and carotenoids. Various alpha beta-unsaturated aldehydes can also react with the amino groups of nucleotides to induce biological alteration. Although age pigments can be produced from different types of biological materials, the crosslinking of carbonyl and amino compounds is a common toxiferous process during biological life. In the context of various aging phenomena and degenerative diseases, this process may constitute an essential mechanism of aging--the carbonyl toxification process of biological aging.

Aging↗
PubMed2004

Gene structure of the goldfish agouti-signaling protein: a putative role in the dorsal-ventral pigment pattern of fish.

One of the most successful chromatic adaptations in vertebrates is the dorsal-ventral pigment pattern in which the dorsal skin is darkly colored, whereas the ventrum is light. In fish, the latter pattern is achieved because a melanization inhibition factor inhibits melanoblast differentiation and supports iridophore proliferation in the ventrum. In rodents, the patterned pigmentation results from regional production of the agouti-signaling protein (ASP). This peptide controls the switch between production of eumelanin and pheomelanin by antagonizing alphaMSH effects on melanocortin receptor (MCR) 1 in the melanocytes. In addition, ASP inhibits the differentiation and proliferation of melanoblast. Thus, the mammalian ASP may be homologous to the poikilotherm melanization inhibition factor. By screening of a genomic library, we deduced the amino acid sequence of goldfish ASP. The ASP gene is a four-exon gene spanning 3097 bp that encodes a 125-amino acid precursor. Northern blot analysis identified two different ASP mRNAs in ventral skin of red- and black-pigmented and albino fish, but no expression levels were observed in the dorsal skin of the same fish. The dorsal-ventral expression polarity was also detected in both black dorsally pigmented fish and albino fish. Pharmacological studies demonstrate that goldfish ASP acts as a melanocortin antagonist at Fugu MC1R and goldfish MC4R. In addition, goldfish ASP inhibited Nle4, D-Phe7-MSH-stimulated pigment dispersion in medaka melanophores. Our studies support agouti signaling protein as the melanization inhibition factor, a key factor in the development of the dorsal-ventral pigment pattern in fish.

Agouti Signaling Protein↗
PubMed2004

Comparative assessment of ocular tissue distribution of drug-related radioactivity after chronic oral administration of 14C-levofloxacin and 14C-chloroquine in pigmented rats.

Fluoroquinolones have been reported to have a high affinity for melanin. The ocular tissue distribution and accumulation of radioactivity was compared after repeated oral administration of 14C-levofloxacin and 14C-chloroquine at daily doses of 20 mg (0.054 mmol) kg(-1) and 28 mg (0.054 mmol) kg(-1), respectively, in pigmented rats for 84 days. The mean serum level at 24 h following each dose of 14C-levofloxacin was almost constant in the range of 0.33-0.45 nmol equiv mL(-1) after the 14th dose and thereafter. The melanin-containing ocular tissues, such as iris ciliary body and stratum pigment chorioides sclera, showed a much higher concentration of radioactivity than other non-pigmented ocular tissues. The respective concentration in iris ciliary body and stratum pigment chorioides sclera after the 1st dose was 126.47 and 74.91 nmol equiv g(-1), and gradually increased with increasing dose number, reaching 1261.81 and 447.45 nmol equiv g(-1) after the 84th dose, which was ca. 10 and 6 times higher, respectively, than after the 1st dose. The mean serum level following each dose of 14C-chloroquine was almost constant in the range 0.51-0.87 nmol equiv mL(-1) after the 7th dose and thereafter. The respective concentration in iris ciliary body and stratum pigment chorioides sclera after the 1st dose was 572.10 and 709.41 nmol equiv g(-1), and gradually increased with increasing dose number, reaching 33 317.92 and 12 322.90 nmol equiv g(-1) after the 84th dose, which was ca. 58 and 17 times higher, respectively, than after the 1st dose. The concentration in aqueous humour, cornea, lens, vitreous body and retina after the 84th dose was 1.84, 6.33, 0.48, 5.60 and 11.42 nmol equiv g(-1) for 14C-levofloxacin and 18.84, 264.99, 27.26, 158.43 and 1020.89 nmol equiv g(-1) for 14C-chloroquine (ca. 10, 42, 57, 28 and 89 times higher, respectively, than for 14C-levofloxacin). Especially, the concentration in the retina was markedly higher after 14C-chloroquine administration than after 14C-levofloxacin administration. The concentration and the extent of accumulation of radioactivity not only in melanin-containing ocular tissues but also in other non-pigmented ocular tissues, such as retina, after chronic oral administration of 14C-levofloxacin once daily for 84 days were much lower than those after multiple dosing with 14C-chloroquine under the same conditions. These results indicate that levofloxacin would have a much lower risk for ocular toxicity than chloroquine after chronic dosing.

Administration, Oral↗
PubMed2004

A unique visual pigment expressed in green, red and deep-red receptors in the eye of the small white butterfly, Pieris rapae crucivora.

The full primary structure of a long-wavelength absorbing visual pigment of the small white butterfly, Pieris rapae crucivora, was determined by molecular cloning. In situ hybridization of the opsin mRNA of the novel visual pigment (PrL) demonstrated that it is expressed in the two distal photoreceptor cells (R3 and R4) as well as in the proximal photoreceptors (R5-8) in all three types of ommatidia of the Pieris eye. The main, long-wavelength band of the spectral sensitivities of the R3 and R4 photoreceptors is well described by the absorption spectrum of a visual pigment with absorption maximum at 563 nm; i.e. PrL is a visual pigment R563. The spectral sensitivities of R5-8 photoreceptors in ommatidial type I and III peak at 620 nm and those in type II ommatidia peak at 640 nm. The large shifts of the spectral sensitivities of the R5-8 photoreceptors with respect to the absorption spectrum of their visual pigment can be explained with the spectral filtering by pale-red (PR) and deep-red (DR) screening pigments that are concentrated in clusters of granules near the rhabdom boundary. The peak absorbance of the two spectral filters appears to be approximately 1 (PR) and 2 (DR).

Amino Acid Sequence↗
PubMed1998

Visual pigments, oil droplets and cone photoreceptor distribution in the european starling (Sturnus vulgaris)

Microspectrophotometric measurements of retinal photoreceptors from the European starling (Sturnus vulgaris) revealed four classes of single cone, containing visual pigments with wavelengths of maximum absorbance ( max) at 563, 504, 449 and close to 362 nm. The two longer-wave-sensitive single cones contained brightly coloured oil droplets which cut off light below 572 and 514 nm, respectively. The 449 nm max pigment was associated with a 'colourless' oil droplet with peak measured absorptance below 400 nm. The ultraviolet-sensitive visual pigment was paired with a transparent oil droplet which showed no significant absorption above 350 nm. A single class of double cone was identified, both members of which contained the longwave-sensitive ( max 563 nm) visual pigment. The principal member of the double cone contained an oil droplet with a topographically variable cut-off wavelength below 471 nm; the oil droplet found in the accessory member was only measured in the ventral retina and displayed three distinct peaks of absorption at approximately 430, 450 and 480 nm. Rod photoreceptors had a max at 503 nm. A new polynomial for fitting visual pigment templates to ultraviolet-sensitive visual pigment data is given. Topographic density measurements of the different cone classes were made using Nitroblue-tetrazolium chloride to label selectively bleached photoreceptors. The two classes of shortwave-sensitive single cone were more abundant in the dorsal retina, and longwave-sensitive single cones were notably less abundant in the dorso-temporal region of the retina, which subserves binocular vision.

Journal Article↗
PubMed2005

Antioxidant activity of the melanin pigment extracted from Aspergillus nidulans.

Melanins are pigments of high molecular weight formed by oxidative polymerization of phenolic or indolic compounds. A number of fungi, including Aspergillus nidulans, produce pigments related or identical to melanin, which are located on cell walls or exist as extracellular polymers. The aim of the present study was to assess the antioxidant activity of synthetic melanin and of the pigment extracted from the mycelium and culture medium after growth of the highly melanized strain (MEL1) from A. nidulans. The ability of the melanin pigment to scavenge the oxidants HOCl and H2O2 was evaluated by inhibition of the oxidation of 5-thio-2-nitrobenzoic acid (TNB) using several melanin concentrations. The results showed that the pigment of the MEL1 strain competes with TNB for H2O2 and HOCl, inhibiting TNB oxidation in a concentration-dependent manner. For the HOCl oxidant, this inhibition was comparable to that of synthetic melanin, whose IC50 values were quite close for both pigments. Thus, our results suggest that the melanin from A. nidulans is a potential HOCl scavenger and may be considered a promising material for the cosmetic industry for the formulation of creams that protect the skin against possible oxidative damage.

Antioxidants↗