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PubMed2003

Pigmentation in the developing seed coat and seedling leaves of Brassica carinata is controlled at the dihydroflavonol reductase locus.

Flavonoid differences between near-isogenic lines of yellow- and brown-seeded Brassica carinata were used to identify a genetic block in seed coat and seedling leaf pigment biosynthesis. Seed coat pigment in the brown-seeded line consisted of proanthocyanidins (condensed tannins), while anthocyanin was absent. Dihydroquercetin, dihydrokaempferol, quercetin and kaempferol accumulated only in the mature seed coat of the yellow-seeded line, indicating dihydroflavonol reductase (DFR) as an element of genetic control in pigment biosynthesis. DFR transcripts from the developing seed coat in the yellow-seeded line were absent or less abundant at 5-30 days after pollination compared to transcript levels in the brown-seeded line. Seedling leaves of the yellow-seeded line exhibited reduced expression of DFR and contained less anthocyanin compared to the respective tissues from plants of the brown-seeded line when grown at 25/20 degrees C (day/night). Cooler (18/15 degrees C) growing temperatures affected seedling leaf pigmentation, mature seed coat colouration and DFR expression in the yellow-seeded line. Comparable brown-seeded line tissues were unaffected by these temperature changes. These results are suggestive of a temperature-sensitive regulator of DFR in the yellow-seeded line of Brassica carinata which ultimately affects the formation of pigments in the seedling leaves and in the mature seed coats.

Alcohol Oxidoreductases↗
PubMed1992

Pigmented adenoma of the optic nerve head simulating a melanocytoma.

PURPOSE: The purpose of this report is to describe a clinicopathologic correlation of an unusual pigmented tumor of the optic nerve head, to point out that such a lesion can simulate clinically a melanocytoma of the optic disc, and to discuss the differential diagnosis of pigmented epipapillary lesions. FINDINGS: Histopathologic studies of the affected eye showed a peculiar pigmented tumor of the optic disc that was compatible with an adenoma arising from the juxtapapillary retinal pigment epithelium. CONCLUSIONS: Adenoma of the retinal pigment epithelium can closely simulate a melanocytoma of the optic disc. There are some clinical features that may serve to differentiate the two lesions.

Adenoma↗
PubMed1996

Laser treatment of tattoos in darkly pigmented patients: efficacy and side effects.

BACKGROUND: Many modalities for the treatment of tattoos and pigmented lesions produce a greater risk of complications in Fitzpatrick types V and VI skin because of an increased incidence of adverse pigmentary changes and keloidal scarring. In fair-skinned persons Q-switched lasers have proved effective in removing pigmented lesions and tattoos without scarring. OBJECTIVE: This study was conducted to determine the efficacy and effects of Q-switched lasers on a small series of darkly pigmented patients with tattoos. METHODS: Four patients of Ethiopian origin with facial and neck tribal tattoos were treated with both the Q-switched ruby and Nd:YAG lasers. One black woman with a multicolored tattoo on the mid chest was treated with the Q-switched ruby laser. RESULTS: Clearing of all lesions was seen. The treatments did not result in scarring or permanent pigment changes other than the ones intended. CONCLUSION: Our results indicate that in darkly pigmented patients, Q-switched laser treatment of tattoos can be performed successfully. The longer wavelength Q-switched Nd:YAG laser is recommended when removing tattoos in darker complected persons. A test treatment is advised before treatment of large skin areas.

Adult↗
PubMed1993

Retinal age pigments generated by self-assembling lysosomotropic detergents.

A universal biomarker of cellular ageing in eukaryotic postmitotic cells is the appearance over time of autofluorescent lysosomal residual bodies called age pigments or lipofuscin granules. Their role in the process of cellular ageing has been debated without resolution. Neither the identity nor mechanism of formation of the fluorophores has been definitively determined. A postmitotic cell type that accumulates large quantities of age pigments is the ocular retinal pigment epithelium. We have now identified the major orange-emitting fluorophore of these pigments using fast-atom bombardment tandem mass spectrometry with collisional activation analysis. It is an amphoteric quaternary amine that arises as a Schiff base reaction product of retinaldehyde and ethanolamine. This compound should display lysosomotropic detergent behaviour which would help explain many of the age-related changes shown in this cell. These results suggest a new role for Schiff base reaction products as lysosomotropic amines in the genesis of cellular age pigments.

Cellular Senescence↗
PubMed2004

Adaptive divergence in pigment composition promotes phytoplankton biodiversity.

The dazzling diversity of the phytoplankton has puzzled biologists for decades. The puzzle has been enlarged rather than solved by the progressive discovery of new phototrophic microorganisms in the oceans, including picocyanobacteria, pico-eukaryotes, and bacteriochlorophyll-based and rhodopsin-based phototrophic bacteria. Physiological and genomic studies suggest that natural selection promotes niche differentiation among these phototrophic microorganisms, particularly with respect to their photosynthetic characteristics. We have analysed competition for light between two closely related picocyanobacteria of the Synechococcus group that we isolated from the Baltic Sea. One of these two has a red colour because it contains the pigment phycoerythrin, whereas the other is blue-green because it contains high contents of the pigment phycocyanin. Here we report theory and competition experiments that reveal stable coexistence of the two picocyanobacteria, owing to partitioning of the light spectrum. Further competition experiments with a third marine cyanobacterium, capable of adapting its pigment composition, show that this species persists by investing in the pigment that absorbs the colour not used by its competitors. These results demonstrate the adaptive significance of divergence in pigment composition of phototrophic microorganisms, which allows an efficient utilization of light energy and favours species coexistence.

Adaptation, Physiological↗
PubMed2005

What features do patients notice that help to distinguish between benign pigmented lesions and melanomas?: the ABCD(E) rule versus the seven-point checklist.

The ABCD(E) rule and the seven-point checklist are diagnostic aids that have proven to be useful in the hands of physicians; however, little is known of their value to patients with respect to aiding self-detection. The objective of this study was to investigate features that patients notice when identifying melanomas and to explore how well these features correspond to the ABCD(E) rule and the seven-point checklist. A retrospective, modified, case-control study involving patient interviews was performed. All interviews were conducted through the private consulting rooms of a Melbourne dermatologist (JWK) and a Newcastle plastic surgeon (CH) prior to the result of pathology being known to the patients and the interviewers. Sixty-seven patients with benign pigmented skin lesions and 46 patients with melanomas were included. Using a logistic regression model, the change in size/new lesion and change in colour (major criteria, seven-point checklist) were most useful in differentiating between melanomas and benign pigmented lesions in the hands of patients [odds ratio (OR), 4.74; 95% confidence interval (CI), 1.85-12.19; P=0.001; OR, 4.27; 95% CI, 1.62-11.26; P=0.003, respectively). The ABCD(E) rule failed to discriminate between melanoma and other benign pigmented skin lesions. It can be concluded that, of the patients' observations, changes in size or colour were most important in distinguishing between benign pigmented lesions and melanomas. Such features therefore deserve emphasis in public education campaigns. Medical professionals should also remember to seek a history of change in assessing pigmented skin lesions.

Case-Control Studies↗
PubMed1994

The removal of cutaneous pigmented lesions with the Q-switched ruby laser and the Q-switched neodymium: yttrium-aluminum-garnet laser. A comparative study.

BACKGROUND: The Q-switched ruby laser (QSRL) (694 nm) has been used successfully in the removal of tattoos and a variety of cutaneous pigmented lesions. The frequency-doubled Q-switched neodymium:yttrium-aluminum-garnet laser (QSNd:YAG) (1064 and 532 nm) has also been shown to be effective in the treatment of tattoos, however, little has been published regarding the QSNd:YAG laser in the removal of cutaneous pigmented lesions. OBJECTIVE: The purpose of this study is to compare the efficacy and side effect profile of the QSRL and the frequency-doubled QSNd:YAG lasers in the removal of cutaneous pigmented lesions, including lentigines, café-au-lait macules, nevus of Ota, nevus spilus, Becker's nevus, postinflammatory hyperpigmentation, and melasma. METHODS: Twenty patients with pigmented lesions were treated with the QSRL and the frequency-doubled QSNd:YAG lasers. Clinical lightening of the lesion was assessed 1 month after a single treatment. Side effects and patient satisfaction were also evaluated. RESULTS: A minimum of 30% lightening was achieved in all patients after only one treatment with either the QSRL or the frequency-doubled QSNd:YAG laser. The QSRL seems to provide a slightly better treatment response than the QSNd:YAG laser. Neither laser caused scarring or textural change of the skin. Most patients found the QSRL to be more painful during treatment, but the QSNd:YAG laser caused more postoperative discomfort. CONCLUSION: Both the QSRL and the frequency-doubled QSND:YAG laser are safe and effective methods of treatment of epidermal and dermal pigmented lesions.

Adult↗
PubMed2003

DNA polymorphism and selection at the melanocortin-1 receptor gene in normally pigmented southern African individuals.

Skin pigmentation is a polygenic multifactorial trait determined by the cumulative effects of multiple genetic variants and environmental factors. Melanocortin-1 receptor (MC1R) is one of the genes involved in pigmentation, and has been implicated in the red hair and pale skin phenotype in human Caucasoid individuals. The present study was undertaken to identify variation at the MC1R locus in normally pigmented individuals in two African populations, sub-Saharan Negroids (22 unrelated individuals) and the San (17 unrelated individuals). The study showed considerable MC1R gene sequence variation with the detection of eight synonymous and three nonsynonymous mutations. This is the first report of nonsynonymous mutations in African individuals in the MC1R gene: L99I was found in a single San individual, S47I was detected in a single Negroid individual, and F196L was detected in five Negroid individuals (5/44; 0.11). The functional significance of these mutations is not known. Three of the eight synonymous mutations found, L106L (CTG --> CTA), F300F (TTC --> TTT), and T314T (ACA --> ACG) (also known as A942G), have been reported previously. T314T was the only variant that showed a significant difference between the Negroid and San populations (0.477 and 0.059, respectively; P = 1.6 x 10(-5)). Its low frequency in the San may be the result of random genetic drift in a population of small size, or selection. Several tests of neutrality of the MC1R coding region in these and other African populations were significant, suggesting that purifying selection (functional constraint) had occurred at this gene locus in Africans. This demonstrates that although some nonsynonymous MC1R mutations are tolerated in individuals with dark skin, this gene has likely played a significant role in the maintenance of dark pigmentation in Africans and normal pigment variation in non-African populations.

Africa↗
PubMed1979

Common origin of pigment cells.

The fundamentally diverse vertebrate pigment cells, melanophores, xanthophores, and iridophores, contain pigmentary organelles known, respectively, as melanosomes, pterinosomes, and reflecting platelets. Their pigments are mealanins pteridines, and purines. Mosaic pigment cells containing more than one type of organelle have been observed and mosaic organelles containing more than one type of pigment have been discovered. It is proposed that the various pigment cells are derived from a stem cell that contains a primordial organelle of endoplasmic reticular origin. This primordial organelle can differentiate into any of the known pigmentary organelles.

Animals↗
PubMed1965

SPECTROPHOTOMETRIC CHARACTERIZATION OF PIGMENTS PRODUCED BY STAPHYLOCOCCUS EPIDERMIDIS STRAINS ISOLATED FROM BOVINE UDDERS.

Sandvik, Olav (National Animal Disease Laboratory, Ames, Iowa), and Richard W. Brown. Spectrophotometric characterization of pigments produced by Staphylococcus epidermidis strains isolated from bovine udders. J. Bacteriol. 89:1201-1208. 1965.-Spectrophotometric analysis of methanol-extracted pigments of 70 isolates, representing 48 strains of Staphylococcus epidermidis, exhibited absorption curves that were classified into seven types, designated I, II, III, IV, V, VI, and a S. aureus type. Two subtypes were included in types I and III. All nonpigmented cell extracts were classified as type I. One of the six numbered type absorption curves was obtained with the majority of isolates. Three isolates gave an absorption curve that was similar to the curve produced by extracts of five of seven S. aureus strains, thus the designation S. aureus type. The differences in pigment complexes indicated by the various absorption curves of methanol extracts were substantiated by column-chromatography studies. Generally, pigments of types II to VI, as produced by representative strains, were of a xanthophyllic nature, whereas, the S. aureus type pigment studied was carotenelike. Analyses of representative strains showed that the type of spectral absorption curves did not change whether the organisms were carried in vitro and tested through 3 months, or isolated repeatedly from infected udders for periods up to 8 months. The method of determining the spectral absorption curves of whole-cell methanol extracts provides an additional tool for differentiating strains of S. epidermidis that can be used in enzootiological studies of udder infections.

Animals↗
PubMed1996

Zebrafish pigmentation mutations and the processes of neural crest development.

Neural crest development involves cell-fate specification, proliferation, patterned cell migration, survival and differentiation. Zebrafish neural crest derivatives include three distinct chromatophores, which are well-suited to genetic analysis of their development. As part of a large-scale mutagenesis screen for embryonic/early larval mutations, we have isolated 285 mutations affecting all aspects of zebrafish larval pigmentation. By complementation analysis, we define 94 genes. We show here that comparison of their phenotypes permits classification of these mutations according to the types of defects they cause, and these suggest which process of neural crest development is probably affected. Mutations in eight genes affect the number of chromatophores: these include strong candidates for genes necessary for the processes of pigment cell specification and proliferation. Mutations in five genes remove part of the wild-type pigment pattern, and suggest a role in larval pigment pattern formation. Mutations in five genes show ectopic chromatophores in distinct sites, and may have implications for chromatophore patterning and proliferation. 76 genes affect pigment or morphology of one or more chromatophore types: these mutations include strong candidates for genes important in various aspects of chromatophore differentiation and survival. In combination with the embryological advantages of zebrafish, these mutations should permit cellular and molecular dissection of many aspects of neural crest development.

Adaptation, Physiological↗
PubMedDate not supplied

Lipofuscin pigment over benign and malignant choroidal tumors.

This study has shown that lipofuscin pigment may accumulate in RPE cells and macrophages over several types of benign and malignant choroidal tumors. The color of the pigment, however, varies with the nature and color of the underlying lesion. On the surface of deeply pigmented tumors the lipofuscin pigment may produce an orange color, whereas over amelanotic lesions it may appear brown or reddish-brown. On the surface of vascular tumors, such as choroidal hemangiomas, the lipofuscin is almost invisible ophthalmoscopically but may be demonstrated with fluorescein angiography. Although the presence of such pigment accumulation is suggestive of a malignant melanoma, it is not diagnostic and may occur over benign simulating lesions as well.

Choroid↗
PubMed2000

[Cellular and molecular features of mammalian pigmentation--tyrosinase and TRP].

Melanin pigments are found in all biological kingdoms. At the cellular level, correct pigmentation depends not only on correct migration of pigment cells (melanocytes) and their precursors (melanoblasts), but also on specialized cytoplasmic organelles, melanosomes. Three pigment cell-specific enzymes inside melanosomes are involved in melanogenesis: tyrosinase, TRP-1 and TRP-2/DOPA-chrome tautomerase. A point mutation of tyrosinase is sufficient to give rise to a nonfunctional enzyme, leading to albinism and associated decreased visual acuity. Several regulatory elements have been identified within the promoters of the genes encoding these three enzymes. These promoter fragments have been used to target the expression of heterogeneous genes in pigment cells of transgenic mice.

Albinism↗
PubMed1978

Breeding a pigmented strain of rats with tapetoretinal degeneration.

When Royal College of Surgeons (RCS) rats are bred with Wistar albinos the offspring are deeply pigmented and have normally functioning retinas. From this second generation, various breeding possibilities exist. In the course of successive cross-breedings one can obtain albinos, tan striped (RCS type) or pigmented animals, any one of which may be normal, carrier or affected. The skin pigmentation trait and that of retinal degeneration are independently inherited and follow autosomal recessive Mendelian laws. However normals for ERG studies vary with skin pigmentation. It is suggested that only one group should be chosen and preferably the pigmented variety.

Albinism↗
PubMed2003

Improved identification of potentially dangerous pigmented skin lesions by computerized image analysis.

BACKGROUND: Melanoma is completely curable if resected early. Unfortunately, early melanoma can be difficult to differentiate from other pigmented lesions. Computerized image analysis instruments have now been developed to assist in determining whether a pigmented lesion is potentially dangerous and requires biopsy. To evaluate whether one such instrument can improve the management of pigmented lesions, we obtained biopsy specimens from 52 pigmented lesions that appeared clinically benign to an experienced dermatologist but were suspicious by image analysis. OBSERVATION: Histologically, 9 (17%) of the lesions that were removed based solely on computer recommendation were potentially dangerous and should have been removed. These included 1 malignant melanoma in situ and 8 dysplastic nevi with moderate to severe cytologic atypia. CONCLUSION: The results of the present study indicate that computerized image analysis can improve the evaluation of pigmented skin lesions by identifying clinically unsuspicious, but potentially dangerous, lesions that might have otherwise have been neglected.

Biopsy, Needle↗
PubMed1999

Idiopathic reactive hyperplasia of the retinal pigment epithelium.

OBJECTIVES: To present and discuss 2 patients with acquired peripapillary pigmented lesions. METHODS: We reviewed the patients' clinical records and histopathologic findings. RESULTS: The first patient was diagnosed with a pigmented papillary lesion that was followed up for 38 years. The second patient was a child with neurofibromatosis type 1 who developed a pigmented peripapillary lesion following excision of an optic nerve glioma. Histologic findings in both cases demonstrated hyperplasia of the retinal pigment epithelium with associated findings. CONCLUSIONS: The lesions presented an idiopathic reactive hyperplasia of the retinal pigment epithelium. The clinical and histopathologic findings resemble findings reported with the combined hamartoma. We suggest that such lesions are reactive in nature, rather than hamartomatous.

Child, Preschool↗
PubMed2006

Iris pigment epithelial translocation in the treatment of exudative macular degeneration: a 3-year follow-up.

OBJECTIVE: To report the functional and anatomical outcome of 20 patients who underwent surgical removal of choroidal neovascularization combined with transplantation of autologous iris pigment epithelial cells to the subretinal space 3 years after treatment. METHODS: Freshly isolated autologous iris pigment epithelial cells were translocated to the subretinal space in 20 patients after membrane extraction. Patients were followed up by funduscopy, angiography, microperimetry, and visual acuity testing. RESULTS: After a follow-up of 3 years, 1 patient showed improved visual acuity, 13 patients retained stable visual acuity, and 3 patients had reduced visual acuity. No macular edema or recurrent choroidal neovascularization was apparent at any time during the follow-up. CONCLUSIONS: Transplanted autologous iris pigment epithelial cells were well tolerated for 3 years and stabilization of visual acuity was achieved in most patients. These results suggest that iris pigment epithelial cells may serve as a substitute for retinal pigment epithelial cells after choroidal neovascularization removal in patients with exudative macular degeneration; however, whether these cells will be of any value for the restoration of vision and possible protection against choroidal neovascularization recurrence awaits further clinical observation and additional research.

Adult↗
PubMed1984

Repair of the pigment epithelial barrier following photocoagulation.

Mild argon laser burns produced in the retina of cynomolgus monkeys underwent differentiated retinal repair with frequent restoration of the pigment epithelial barrier. Permeability of the restored barrier was tested by two tracers injected intravenously--horseradish peroxidase followed by electron microscopic evaluation and fluorescein sodium followed by fluorescence microscopic examination of freeze-dried tissue. Tightness of the barrier was associated with regularly arranged pigment epithelial cells joined by zonulae occludentes. Leakage of the barrier was associated with discontinuities in the line of regularly proliferated pigment epithelial cells. At times, the tracers stained the pigment epithelial cells diffusely but they did not accumulate in the subretinal space. Variable changes in the choriocapillaris were noted. Mild photocoagulation may be effective in treating central serous choroidopathy in man when restoration of the pigment epithelial barrier is stimulated.

Animals↗