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PubMed1981

Pigment release.

Guttae phenylephrine 10% produced a significant decrease in intraocular pressure and increase in facility of outflow in eyes with untreated ocular hypertension. If at the same time pigment was released into the aqueous, the pressure and outflow effect was nullified. Guttae pilocarpine 2% also reduced pressure and increased outflow, but if phenylephrine was added to the pilocarpine 2 responses appeared. If no pigment was released, pressure decreased and outflow increased; if pigment was released, there was no significant change in either. An identical response was shown by eyes with treated open-angle glaucoma. In eyes with treated exfoliation glaucoma pilocarpine and phenylephrine combined produced a significant increase in pressure and decrease in outflow because of pigment release. Finally, 18 eyes are described in which pigment release produced a mean increase in intraocular pressure of 14 mmHg. An acute release of pigment has an outflow-blocking effect that can be readily demonstrated. It provides an explanation for some of the paradoxical responses that occur after the instillation of autonomic drugs. It also provides a sufficient explanation for glaucoma associated with pigment dispersion.

Drug Combinations↗
PubMed2003

Comparison of iridial pigmentation between latanoprost and isopropyl unoprostone: a long term prospective comparative study.

AIM: To compare incidence of iridial pigmentation prospectively induced by long term treatment with latanoprost and isopropyl unoprostone (hereafter, unoprostone) in Japanese patients with glaucoma. METHODS: Patients with glaucoma treated with prostaglandin (PG) related ophthalmic solutions were sequentially enrolled. Patients treated for more than 30 months with PG related ophthalmic solutions were subjected to analysis. The entry criteria were no history of intraocular surgery, laser iridotomy, and/or laser trabeculoplasty within 12 months before and after the enrolment; and no history of uveitis; no changes in antiglaucoma drugs within 6 months before and after the enrolment. Photographs of the irides were taken under the same conditions and three glaucoma specialists evaluated the iridial pigmentation with masking of patient information. The correlation of iridial pigmentation with the background factors and the reduction of intraocular pressure (IOP) before and after the treatment were investigated. RESULTS: 48 eyes in 48 patients satisfied the enrolment criteria (25 eyes in the latanoprost group, 23 eyes in the unoprostone group). At the end of the follow up period, iridial pigmentation was present in 15 patients (60.0%) in the latanoprost group and seven patients (30.4%) in the unoprostone group. The correlation between development of iridial pigmentation and age, sex, concurrent use of other ophthalmic solutions, and IOP reduction was not significant. CONCLUSIONS: The incidence of iridial pigmentation induced by latanoprost or unoprostone is high in the case of long term treatment. Iridial pigmentation did not affect PG related ophthalmic solution induced IOP reduction.

Adult↗
PubMed2004

Association between choroidal pigmentation and posterior uveal melanoma in a white population.

BACKGROUND/AIMS: It is well known that light skin pigmentation is a risk factor for cutaneous melanoma. The aim of this study was to investigate the analogous association between choroidal pigmentation and posterior uveal melanoma. METHODS: Cross sectional study of 65 consecutive patients diagnosed with posterior uveal melanoma (melanoma group) and 218 consecutive patients referred for general retinal evaluation (control group). All patients were white. A clinical grading system for estimating choroidal pigmentation was developed and histologically validated in seven patients. RESULTS: Melanoma patients with light iris colour were significantly more likely to have darker choroidal pigmentation than controls (p = 0.005). Darker choroidal pigmentation was associated histologically with increased density of choroidal melanocytes (p = 0.005). CONCLUSIONS: Increased choroidal pigmentation, as a result of an increase in the density of pigmented choroidal melanocytes, is not protective but may actually be a risk factor for the development of posterior uveal melanoma in white patients. This finding may have implications for understanding the pathogenesis of uveal melanoma.

Adult↗
PubMed1989

Brown pigmentation in Serratia marcescens cultures associated with tyrosine metabolism.

Serratia marcescens produced a brown pigment when grown in minimal medium in the presence of tyrosine and high concentrations of copper(II) ion. The pigment was not related to the melanin pigments, but was similar to the pigment produced by autooxidation and polymerization of 3,4-dihydroxyphenylacetate, which is synthesized in S. marcescens from tyrosine through the 3,4-dihydroxyphenylacetate catabolic pathway. The enzymes of this pathway were induced under pigment production conditions; however, 3,4-dihydroxyphenylacetate 2,3-dioxygenase remained at low activity levels, permitting the accumulation and excretion of the substrate. Mutants unable to use tyrosine as a sole carbon and energy source were able to produce brown pigments only if the step blocked by the mutation was after the synthesis of 3,4-dihydroxyphenylacetate. The ability to produce brown pigments was common to all the S. marcescens strains tested.

Chemical Phenomena↗
PubMed1998

Reticulate, patchy and mottled pigmentation of the neck. Acquired forms.

Besides the inherited forms of mottled and reticulate pigmentation, a vast number of diseases and trigger mechanisms can lead to acquired pigmentation of the neck. Nonhereditary variants of reticulate and mottled pigmentation can affect the neck as a typical site and therefore may give a diagnostic clue or it can occur sporadically on the neck as well as on other sites. A well-known and important factor in the pathogenesis is exposure to sunlight. Sun-induced pigmentation often presents on the neck and may result from phototoxic, photoallergic and cumulative actinic damage. Frequent forms comprise berloque dermatitis, Riehl's melanosis, poikiloderma of Civatte and tanning bed lentigines. Different infections may also lead to this distinct skin alteration as pediculosis capitis, pityriasis versicolor and syphilis II. Treatment-induced irregular pigmentations may occur after applications of topical agents (e.g. diphenylcyclopropenone), systemic medication (e.g. 5-fluorouracil, chlorpromazine), as a complication of laser resurfacing or as a chronic graft-versus-host reaction. Different neoplasms may also involve the neck. Widespread pigmented basal cell carcinoma, cutaneous T-cell lymphoma, syringolymphoid hyperplasia and histiocytic diseases may lead to reticulated pigmentation. Various other infrequent conditions as connective tissue diseases, malnutrition, lichen planus pigmentosus and others are summarized. The neck, a readily accessible site to medical inspection, may have an underestimated value for the diagnosis of different skin diseases.

Humans↗
PubMed2001

Transdifferentiation of pigmented epithelial cells: a source of retinal stem cells?

In urodeles, larval anurans, embryonic chicks and rodents, the retinal pigmented epithelium (RPE) is capable of transdifferentiation and generating new neurons. Recent evidence suggests that pigmented cells in the ciliary body of the adult rodent eye are capable of producing new neurons in vitro. Here we provide data to suggest that the pigmented epithelium at the retinal margin of postnatal chickens is similar to that found in the embryonic retina. Pigmented cells at the retinal margin expressed mitf and pax6, transcription factors that are transiently expressed by the developing RPE. Furthermore, these pigment cells at the retinal margin express high levels of proliferating cell nuclear antigen and accumulate bromodeoxyuridine, indicating that they continue to proliferate long after embryonic stages of development. Exogenous fibroblast growth factor-2 (FGF2) or insulin alone did not affect the proliferation of these cells, while FGF2 plus insulin induced their proliferation and loss of pigmentation. We propose that the pigmented cells at the retinal margin of the postnatal chicken are similar to those found in the embryonic eye, and these cells could be a source of neural regeneration under appropriate conditions.

Animals↗
PubMed1996

CD36 participates in the phagocytosis of rod outer segments by retinal pigment epithelium.

Mechanisms of phagocytosis are complex and incompletely understood. The retinal pigment epithelium provides an ideal system to study the specific aspects of phagocytosis since an important function of this cell is the ingestion of packets of membranous discs that are normally discarded at the apical ends of rod and cone cells during outer segment renewal. Here we provide evidence that rod outer segment phagocytosis by retinal pigment epithelium is mediated by CD36, a transmembrane glycoprotein which has been previously characterized on hematopoietic cells as a receptor for apoptotic neutrophils and oxidized low density lipoprotein. Immunocytochemical staining with monoclonal and polyclonal antibodies demonstrated CD36 expression by both human and rat retinal pigment epithelium in transverse cryostat sections of normal retina and in primary cultured cells. By western blot analysis of retinal pigment epithelial cell lysates, polyclonal and monoclonal antibodies to CD36 recognized an 88 kDa protein which comigrated with platelet CD36. Furthermore, the synthesis of CD36 mRNA by retinal pigment epithelium was confirmed by reverse transcriptase-PCR using specific CD36 oligonucleotides. The addition of CD36 antibodies to cultured retinal pigment epithelial cells reduced the binding and internalization of 125I-labeled rod outer segments by 60%. Immunofluorescence confocal microscopy confirmed that outer segment uptake was significantly diminished by an antibody to CD36. Moreover, we found that transfection of a human melanoma cell line with CD36 cDNA enabled these cells to bind and internalize isolated photoreceptor outer segments as seen by double immunofluorescent staining for surface bound and total cell-associated rod outer segments, and by measurement of cell-associated 125I-labeled rod outer segments. We conclude that the multifunctional scavenger receptor CD36 participates in the clearance of photoreceptor outer segments by retinal pigment epithelium and thus, participates in the visual process.

Aged↗
PubMed2005

Chromatic interaction between egg pigmentation and skin chromatophores in the nuptial coloration of female two-spotted gobies.

In two-spotted gobies (Gobiusculus flavescens Fabricius 1779), females develop an orange belly as they approach sexual maturity. Bright belly coloration is preferred by males and has been suggested to act as a female ornament. This coloration is unusual in that it originates partly from pigmentation of the abdominal skin but also from strongly pigmented gonads directly visible through the skin. In addition, females have been observed to temporarily become more colourful during courtship and competition. To understand how gonad and skin pigmentation interact in this nuptial coloration, the potential for colour modification via regulation of skin chromatophores was investigated. Noradrenaline caused aggregation of chromatophore pigment and was used to experimentally reduce the contribution of skin chromatophores to the nuptial coloration. Chromatophore pigment aggregation caused bellies to become less colourful and abdominal skin biopsies to become less colourful and more transparent. There was a strong positive relationship between belly coloration and the coloration of the underlying gonads. This shows that belly coloration honestly reflects egg pigmentation, mainly because the transparency of the abdominal skin allows other fish to see the gonads directly. Interestingly, when noradrenaline caused pigment to aggregate and thereby increased the transparency of the skin, the relationship between belly and gonad coloration weakened. We conclude that female G. flavescens have a potential to use skin chromatophores to rapidly alter their nuptial coloration, thereby affecting the efficacy with which information about gonad coloration is conveyed.

Animals↗
PubMed2000

Cone pigment gene expression in individual photoreceptors and the chromatic topography of the retina.

Human trichromatic vision is based on three classes of cones: L, M, and S (long-, middle-, and short-wavelength sensitive, respectively). Individuals can have more than one M and/or more than one L pigment gene on the X chromosome along with an S pigment gene on chromosome 7. In some people the X-linked pigment gene array can include polymorphic variants that encode multiple, spectrally distinct cone photopigment subtypes. A single-cell, polymerase chain reaction approach was used to examine visual pigment gene expression in individual human cone cells and identify them as L or M. The ratio of L:M pigment gene expression was assayed in homogenized retinal tissues taken from the same eyes. Results indicate that there is a close correspondence between the cone ratio determined from counting single cells and the L:M pigment mRNA ratio estimated from homogenized pieces of retina. The results also show that the different pigment genes in one array are often expressed at very different levels, giving rise to unequal numbers of L and M cones. Expression of only one photopigment gene was detected in each cone cell. However, individual males can have more than the classically described three spectrally distinct cone types in their retinas.

Adult↗
PubMed2005

Association of melanin pigmentation in the gingiva of children with parents who smoke.

OBJECTIVE: The association between gingival pigmentation and active smoking has been established. This investigation is the first to address the relationship between gingival pigmentation in children and passive smoking. METHODS: A case-control study was performed involving 59 nonsmoking children who were selected from patient records of a dental clinic in a rural town in Japan. The number of subjects was based on a power calculation. Two calibrated examiners independently observed labial gingiva via oral photographs. RESULTS: An interview determined that 61% of children had at least 1 smoking parent. Gingival pigmentation was observed in 71% to 78% of children. Interexaminer agreement was satisfactory (kappa = 0.73). Percentage of smoking parents was higher in children with gingival pigmentation (70-71%) than in those who lacked pigmentation (35%). Odds ratios of parental smoking adjusted by age and gender were 5.6 (95% confidence interval: 1.5-20.0) and 5.4 (1.4-21.2) for the 2 examiners. CONCLUSION: These findings suggest that excessive pigmentation in the gingiva of children is associated with passive smoking. The visible pigmentation effect in gingiva of children could be useful in terms of parental education.

Adolescent↗
PubMed2007

Diffuse pigmentation of maxillary attached gingiva: four cases of the cultural practice of gingival tattoo.

BACKGROUND: Gingival pigmentation is a common finding, may be of endogenous or exogenous origin, and can have diagnostic significance. Diffuse gingival pigmentation may be physiologic in nature or can be due to environmental factors, drugs, endocrine disorders, or genetic conditions. We present four cases of diffuse gingival pigmentation due to traditional gingival tattooing and review the literature on this practice. METHODS: Four black females (aged 19 to 56 years) of West African origin (Mauritania and Senegal), representing three different ethnic groups (Fulani, Mandinka, and Soninke) presented with various chief complaints. All exhibited diffuse pigmentation of the maxillary vestibular gingiva extending to the second premolar areas, without any associated radiographic abnormalities. The color ranged from intense blue gray to light gray or grayish pink. One case was biopsied for histopathologic evaluation. RESULTS: Questioning revealed that the women had had one or more sessions of traditional gingival tattooing. In one case, the procedure was performed in a dental office. The color range appeared to depend on the time that elapsed since the last procedure. The biopsy exhibited dense fibrous connective tissue containing aggregates of foreign material consistent with a foreign body tattoo. CONCLUSIONS: Gingival tattooing, a cultural practice prevalent in certain African ethnic groups, results in diffuse pigmentation. Outside of Africa, it may be misinterpreted as racial pigmentation or pose a diagnostic puzzle. The color and distribution pattern of diffuse gingival pigmentation often are quite suggestive, and the clinical diagnosis should be confirmed by patient history. In selected cases, biopsy may be necessary to exclude other diagnostic considerations.

Adult↗
PubMedDate not supplied

Effects of aging on normal hearing loss and noise-induced threshold shift in albino and pigmented guinea pigs.

In a previous investigation into noise-induced hearing loss by comparing 2-month-old albino with pigmented guinea pigs, albinos displayed significantly greater shifts in cochlear microphonic (CM) threshold and less recovery than the pigmented animals 7 days after noise exposure. The present study compared the responses of 14-month-old albino and pigmented guinea pigs to the same noise parameters used previously. Thresholds for the first detectable elicitation of CM for three pure tones were recorded prior to, at 90 min and at 7 days after a 45-min exposure to 126 dB broadband noise. Before exposure to noise, thresholds for pigmented guinea pigs were 24 dB higher than those in the albinos. Following noise exposure, the pigmented animals showed less than half the amount of threshold shift displayed by the albinos. This change ws attributed to the higher pre-exposure thresholds in the pigmented guinea pigs. Converging lines of evidence suggest that cochlear pigmentation may have both protective and toxic influences on the inner ear.

Aging↗
PubMed1988

Melanosome abnormalities of ocular pigmented epithelial cells in beagle dogs with hereditary tapetal degeneration.

Eyes of laboratory beagle dogs with an inherited tapetal degeneration were abnormally lightly pigmented. The development of pigmentation was followed morphologically from 7 days postnatal to 9 years of age. At all postnatal ages the iris pigmented epithelia contained no normal melanosomes, only organelles resembling secondary lysosomes or residual bodies. The ciliary body pigmented epithelium contained a variety of melanosome organelles at the earliest stages examined, but in fewer numbers than in normal animals. These included premelanosomes, partially melanized and some fully melanized pigment granules. However, the melanin deposition was usually patchy and irregular. With time, many of these granules appeared to condense into residual bodies. The retinal pigmented epithelium in peripheral and inferior posterior regions of affected animals never contained normal appearing melanin granules at any stage of postnatal development. The iris and choroidal stroma had melanosomes of normal size and shape, but many fewer than in normal animals. These results imply that there is local cellular control over melanosome production and regression, since the melanosome abnormalities do not follow the anterior to posterior development of pigment in ocular epithelia. It is proposed that a defect in synthesis of the matrix component of melanosomes could result in absent or abnormal deposition of melanin and initiate a process of autophagy of these organelles.

Animals↗
PubMed1988

Patterns of pigment accumulation in Plasmodium falciparum trophozoites in peripheral blood samples.

Ninety-five samples of peripheral blood from patients with Plasmodium falciparum malaria in southwest Saudi Arabia were examined by Giemsa staining and darkfield microscopy under flow condition. Eighty-four samples contained trophozoites (ring forms) only and 11 samples contained gametocytes and trophozoites. Two patterns of pigmentation were observed in the trophozoite-containing samples: 48 (57%) contained trophozoites in which no pigment could be detected, 32 (38%) contained trophozoites with clearly detectable pigment, and 4 (5%) contained both pigmented and nonpigmented forms. Trophozoite pigmentation did not correlate with percent parasitemia or age or sex of the patients. These results indicate that microscopically observable pigment accumulation in trophozoites of P. falciparum is not required during the asexual multiplication cycle. Pigment accumulation may be triggered later in infection, perhaps as a feature of the differentiation process leading to the formation of gametocytes.

Age Factors↗
PubMedDate not supplied

[Microbial sources of pigments].

Pigments from natural sources has been obtained since long time ago, and their interest has increased due to the toxicity problems caused by those of synthetic origin. In this way the pigments from microbial sources are a good alternative. Some of more important natural pigments, are the carotenoids, flavonoids (anthocyanins) and some tetrapirroles (chloropyls, phycobilliproteins). Another group less important are the betalains and quinones. The carotenoids are molecules formed by isoprenoids units and the most important used as colorant are the alpha and beta carotene which are precursors of vitamin A, and some xantophylls as astaxanthin. The pigment more used in the industry is the beta-carotene which is obtained from some microalgae and cyanobacteria. The astaxanthin another important carotenoid is a red pigment of great commercial value, and it is used in the pharmaceutical feed and acuaculture industries. This pigments is mainly obtained from Phaffia rhodozyma and Haematococcus pluvialis and other organisms. The phycobilliproteins obtained from cyanobacteria and some group of algae, have recently been increased on the food industries. In the last years it has been used as fluorescent marker in biochemical assays. Our research group have carried out studies about the factors that improve the production of these pigments obtained from different microbial species as well as the methods for their extraction and application.

Carotenoids↗
PubMed2001

In vitro quantitative chemical analysis of tattoo pigments.

BACKGROUND: The composition of cosmetic tattoos might prove relevant to their treatment by high-powered lasers. OBJECTIVES: To test the accuracy and completeness of information supplied by the tattoo ink manufacturers and to perform an elemental assay of tattoo pigments using scanning electron microscopy with energy-dispersive x-ray analysis. DESIGN: Samples of 30 tattoo inks were examined using "standardless" energy-dispersive spectrometry. This technique uses quantitative electron x-ray microanalysis. The technique reliably identifies all elements with the exception of those elements with atomic numbers less than 11. SETTING: A major national referral laboratory for microscopic examination and biochemical analysis of tissue. These results were compared with ink compositions compiled from manufacturer-supplied material safety data sheets. MAIN OUTCOME MEASURES: (1) The percentage of any given element in whole tattoo pigments. (2) The presence or absence of elements and/or compounds as recorded in material safety data sheets supplied by the tattoo ink manufacturers. RESULTS: Of the 30 tattoo inks studied, the most commonly identified elements were aluminum (87% of the pigments), oxygen (73% of the pigments), titanium (67% of the pigments), and carbon (67% of the pigments). The relative contribution of elements to the tattoo ink compositions was highly variable between different compounds. Overall, the manufacturer-supplied data sheets were consistent with the elemental analysis, but there were important exceptions. CONCLUSION: The composition of elements in tattoo inks varies greatly, even among like-colored pigments. Knowledge of the chemical composition of popular tattoo inks might aid the clinician in effective laser removal.

Electron Probe Microanalysis↗
PubMed2002

Correlation between rod photoreceptor numbers and levels of ocular pigmentation.

PURPOSE: Ocular melanin synthesis modulates rod photoreceptor production, because in albino eyes, rod numbers are reduced by approximately 30%. In this study, rod numbers and ocular rhodopsin concentrations were measured in intermediate pigmentation phenotypes to determine whether proportional reductions in melanin are correlated with proportional changes in rod numbers. Further, patterns of cell production and death were examined around the time of birth, when rod production peaks, to determine whether there are abnormalities in these features associated with hypopigmentation. METHODS: Four mouse pigmentation phenotypes were used: fully pigmented, albino, Beige, and Himalayan. The latter two are intermediate-pigmentation phenotypes, with Beige having markedly more pigment than Himalayan. Ocular melanin concentrations were measured during development and at maturity. Rods were counted at maturity and measurements of ocular rhodopsin undertaken. Mitotic and pyknotic cells were also counted in neonates. RESULTS: Rods and ocular rhodopsin were reduced in both Beige and Himalayan mice below levels found in fully pigmented mice, but not to levels found in albino animals. This was more marked in Himalayan than Beige mice, reflecting the lower concentration of melanin found in the former compared with the latter, both in development and at maturity. Although patterns of cell production were elevated in the hypopigmented animals, such patterns varied. CONCLUSIONS: Rod numbers are modulated within a range between that in fully pigmented and albino phenotypes by the concentration of ocular melanin. However, in these animals, there is no obvious correlation between these events and patterns of cell production and death in neonates.

Albinism, Ocular↗
PubMed1999

[Experimental studies on the cancer chemoprevention of tea pigments].

A batch of short-term tests were used to examine the effects of tea pigments on three stages of carcinogenesis, i.e. initiation, promotion and progression. Forward gene mutation test and micronuclei test were used to study the initiation stage of carcinogenesis; metabolic cooperation test and mice ear test to study the promotion stage. Viability and growth ability of Hela cells in soft agar and S180 solid tumor test in mice were used to examine the effect of tea pigments on the third stage of carcinogenesis. The results showed that both tea pigments and tea polyphenols had significantly protective effects on initiation, promotion and progression stages in carcinogenesis. In vitro study showed that tea pigments and tea polyphenols could induce QR and GST activity in Hep G2 cells. Oral administration of 0.1% tea polyphenols and 0.1% tea pigments could increase GST activity in rat liver by 25% and 18% respectively, and this increase was accompanied by the significant increase of GST 1-1, 1-2 and 3-3 protein expression level in rat liver. Our results suggested that the anticancer effect of tea pigments was the same as that of tea polyphenols, and the anticancer properties of tea pigments might be mediated by activating the enzymes such as QR and GST, which play important roles in the detoxification and exclusion of carcinogen.

3T3 Cells↗