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PubMed1994

Suppression of cAMP-induced pigment granule aggregation in RPE by organic anion transport inhibitors.

PURPOSE: To investigate the mechanism(s) by which intracellular cAMP levels are elevated to induce pigment granule aggregation in teleost retinal pigment epithelium (RPE). METHODS: Pigment granule migration was studied in vitro using RPE sheets isolated from dark-adapted green sunfish, Lepomis cyanellus. After preculture to allow pigment granule dispersion, RPE sheets were incubated with various agents to test their ability to induce pigment granule aggregation. RPE sheets were then fixed, and pigment granule position was assessed microscopically. RESULTS: Pigment granule aggregation was induced by nonderivatized cAMP. At maximally effective concentration (1 mM), cAMP was as effective as its more membrane-permeant analogs dbcAMP and 8-Br-cAMP. Forskolin (1 or 10 microM), a stimulator of adenylyl cyclase, was also effective at inducing pigment aggregation. Two inhibitors of organic anion transport, probenecid and sulfinpyrazone, inhibited cAMP-induced aggregation by approximately 80% but had no effect on forskolin-induced aggregation. Several agents shown to stimulate RPE adenylyl cyclase in other species failed to induce pigment aggregation in isolated RPE sheets. CONCLUSIONS: Our observations strongly suggest that exogenously applied, nonderivatized cAMP can gain access to the cytoplasm of isolated RPE cells via organic anion transporters. Thus, if cAMP were secreted by retinal cells into the subretinal space, it could be taken up by RPE cells and subsequently act as an intracellular messenger to activate dark-adaptive physiological processes such as pigment granule aggregation.

Animals↗
PubMed1963

SELECTIVE INHIBITION OF PROLINE-INDUCED PIGMENTATION IN WASHED CELLS OF SERRATIA MARCESCENS.

Blizzard, John L. (University of Houston, Houston, Texas) and G. E. Peterson. Selective inhibition of proline-induced pigmentation in washed cells of Serratia marcescens. J. Bacteriol. 85:1136-1140. 1963.-Streptomycin, chloramphenicol, and tetracyclines inhibited the synthesis of prodigiosin by Serratia marcescens strain D1. This occurred at concentrations of the antibiotic too low to inhibit the growth of the organism in either agar media or broth cultures. Nonpigmented cells were produced in broth by either adding streptomycin or incubating at 37 C. After being washed and resuspended in aqueous saline containing either casein hydrolysate, l-proline, or a glycine-succinate mixture and incubated at 27 C for 24 hr, these cells formed pigment. The appearance of pigment was preceded by a lag period of 10 hr. Prodigiosin production by these washed suspensions of cells was completely inhibited by either streptomycin or glucose, or by incubation at 37 C instead of 27 C. Even though pigmentation by washed-cell suspensions was induced by proline, the utilization of proline was not affected by streptomycin or glucose, or by incubation at 37 C. To block pigmentation completely, streptomycin had to be added to proline-supplemented cells before they were 10 hr old. Addition of the antibiotic after the end of the induction period caused either partial or no inhibition of pigment production. Streptomycin caused an increase in the endogenous respiration of S. marcescens but failed to affect the constitutive enzymes that oxidize glucose. The possible relationships of these phenomena are discussed. Weil (1952) reported that low concentrations of chloramphenicol and certain tetracyclines inhibit the synthesis of prodigiosin while permitting growth by Serratia marcescens. He noted the potential value to "mode-of-action" studies of an organism having certain functions selectively inhibited by antibiotics. We confirmed Weil's (1952) observations and found that streptomycin at low concentration would also inhibit the synthesis of prodigiosin without impeding growth. Further studies of the selective inhibition of prodigiosin synthesis by streptomycin were performed using nonproliferating suspensions of washed cells (Gott and Williams, 1961). Either a glycine-succinate mixture or l-proline could cause nonproliferating cells to form pigment. A period of induction preceded the formation of pigment. Either streptomycin or glucose, or an incubation temperature of 37 C, inhibited the proline-induced pigmentation by washed cells. Further investigations provided insights to these findings.

Amino Acids↗
PubMed1997

Apoprotein structure in the LH2 complex from Rhodopseudomonas acidophila strain 10050: modular assembly and protein pigment interactions.

The refined structure of the peripheral light-harvesting complex from Rhodopseudomonas acidophila strain 10050 reveals a membrane protein with protein-protein interactions in the trans-membrane region exclusively of a van der Waals nature. The dominant factors in the formation of the complex appear to be extramembranous hydrogen bonds (suggesting that each apoprotein must achieve a fold close to its final structure in order to oligomerize), protein-pigment and pigment-pigment interactions within the membrane-spanning region. The pigment molecules are known to play an important role in the formation of bacterial light-harvesters, and their extensive mediation of structural contacts within the membrane bears this out. Amino acid residues determining the secondary structure of the apoproteins influence the oligomeric state of the complex. The assembly of the pigment array is governed by the apoproteins of LH2. The particular environment of each of the pigment molecules is, however, influenced directly by few protein contacts. These contacts produce functional effects that are not attributable to a single cause, e.g. the arrangement of an overlapping cycle of chromophores not only provides energy delocalisation and storage properties, but also has consequences for oligomer size, pigment distortion modes and pigment chemical environment, all of which modify the precise function of the complex. The evaluation of site energies for the pigment array requires the consideration of a number of effects, including heterogeneous pigment distortions, charge distributions in the local environment and mechanical interactions.

Apoproteins↗
PubMed1989

The human oral raphe system. Architectonics and neuronal types in pigment-Nissl preparations.

Serial sections (15 microns, 120 microns, and 400 microns) of nine brain stems treated with a combined lipofuscin pigment-Nissl stain were examined in order to delineate the three-dimensional conformation and subdivisions as well as the neuronal types of the human oral raphe system. Characteristic lipofuscin deposits within the somata of various cell types facilitated the demarcation of the oral raphe nuclei from surrounding structures. The dorsal, central, and linear raphe nuclei, e.g. the major subdivisions of the oral raphe system, share common traits as far as neuronal composition and pigmentation is concerned. The interfascicular subnucleus, the dorsofascicular subnucleus, and the intercalate subnucleus are minor subdivisions of the dorsal raphe nucleus. The intercalate one cannot be differentiated from surrounding areas in preparations solely stained for Nissl-material, while it can facilely be identified in combined pigment-Nissl preparations by virtue of differences in the pigmentation pattern. Our architectonical concept of the oral raphe system is in good accordance with the one derived from immunocytochemical investigations of serotonin-containing neurons in the human brain stem. Furthermore, five main neuronal types are described which constitute the oral raphe nuclei. They have been differentiated according to their characteristics as seen in combined pigment-Nissl preparations. I) Large ovoid to polygonal neurons with densely packed and intensely stained pigment granules. II) Similarly featured cells displaying dust-fine and faintly stained pigment granules. III) Medium-sized, ovoid to polygonal neurons with loosely distributed, small pigment granules. IV) Small ovoid neurons devoid of pigment or with only few, intensely stained granules. V) Small spindle-shaped nerve cells with various amounts of intensely stained pigment granules.(ABSTRACT TRUNCATED AT 250 WORDS)

Autopsy↗
PubMed1989

Differential susceptibility to gentamicin ototoxicity between albino and pigmented guinea pigs.

The known chemical affinity of melanin pigment for aminoglycoside antibiotics has led to the suggestion that higher concentrations of these drugs will bind to the pigmented inner ear and produce greater ototoxicity compared to the nonpigmented albino cochlea. Although this has provided a compelling hypothesis, results from the few investigations to address this question have been equivocal. In the present study, cochlear microphonic (CM) thresholds were recorded from albino and pigmented guinea pigs both before and two weeks after exposure for 14 consecutive days to 100 mg/Kg gentamicin. Cochleae were dissected and half-turn segments prepared for surface examination of the organ of Corti. After gentamicin exposure, threshold shifts averaged a statistically reliable 33 dB in albinos and 19 dB for the pigmented animals. Anatomical studies revealed a significant 44% mean outer hair cell loss in albinos compared to a 21% loss in the pigmented inner ears. The results showed that albinos display greater ototoxicity from gentamicin than do pigmented guinea pigs. Aminoglycosides are known to exert toxicity through interaction with polyphosphoinositides found in high concentrations in the inner ear. Cochleae in both albino and pigmented animals appear to possess significant phospholipid concentrations and bind toxic levels of these drugs independent of inner ear pigment content. However, evidence showing that melanin can inhibit aminoglycoside activity in vitro suggests that, once these drugs bind to pigmented tissue, they may undergo inactivation in a manner unavailable to the nonpigmented albino cochlea. The present results are consistent with the possibility that cochlear melanin may inhibit gentamicin activity in vivo and decrease the severity of aminoglycoside ototoxicity in the pigmented inner ear.

Acoustic Stimulation↗
PubMed2000

Pigment signatures associated with an anoxic coastal zone: Bahia Concepcion, Gulf of California.

Bahia Concepcion is a coastal lagoon that has bottom anoxic conditions and high pigment concentrations during the summer. The phytoplankton responsible for this pigment increase is enigmatic, therefore we sampled the lagoon to analyze the pigment with a C8-HPLC system to look for signatures of phytoplankton groups. Analysis reveals a low pigment concentration in the mixed layer with a higher concentration of zeaxanthin and increasing values of chlorophyll a, peridinin, and fucoxanthin below, which peaked at the depth where oxygen dramatically decreases and H(2)S increases. Below this depth, a high pigmentation was recorded and the most important signatures were six chlorophyll-like pigments that eluted between the fucoxanthin and the chlorophyll a, and one carotenoid that eluted just after the chlorophyll a. Spectral characteristics of these last pigments are very similar to pigments present in the Chlorobiales group. These results suggest that cyanobacteria, diatoms, and dinoflagellates are responsible for the chlorophyll a increases, though in highly pigmented samples, anoxygenic phototrophic bacteria are probably the main contributors to the increase in pigments.

Journal Article↗
PubMed1995

Prevention of blinking alters iris configuration in pigment dispersion syndrome and in normal eyes.

PURPOSE: To examine the effect of blinking on iris configuration and aqueous humor distribution between the posterior and anterior chambers in eyes with pigment dispersion syndrome compared with healthy eyes. METHODS: High-resolution, anterior segment ultrasound biomicroscopy was performed on ten eyes of ten patients with untreated pigment dispersion syndrome and on ten control subjects. Patients were scanned continuously for 15 minutes or until the maximal change in iris configuration occurred. During this time, the eyelids were held open mechanically, and blinking was prevented. Eyes then were rescanned immediately after blinking. RESULTS: Initial iris configuration was concave in all eyes with pigment dispersion syndrome, whereas in control eyes it was concave in four eyes, planar in four eyes, and convex in two eyes. Iridozonular contact occurred in eyes with pigment dispersion syndrome only. Iridolenticular contact was greater in eyes with pigment dispersion syndrome than in control eyes. Analysis of covariance controlling for age, sex, and refractive error showed pigment dispersion syndrome to be a significant predictor of increased iris concavity. During continuous scanning, the mean change in iris position, from most concave to most convex, and mean time to the maximal change in iris configuration were greater for eyes with pigment dispersion syndrome than in control eyes and were related to the degree of initial iris concavity only (analysis of covariance). In six eyes with pigment dispersion syndrome, the eye cup was removed, normal blinking was permitted, and the eye was rescanned. The iris resumed a concave configuration in all eyes. CONCLUSION: Increased iris concavity in pigment dispersion syndrome appears to be related to increased iridolenticular contact. This creates an anatomic configuration that predisposes to reverse pupillary block. The accumulation of aqueous humor in the posterior chamber, when blinking is prevented, alters iris position in pigment dispersion syndrome and in healthy eyes and increases iridozonular and iridociliary-process distances while minimizing iridolenticular contact. Normal blinking appears to create transient vector forces which promote aqueous humor flow from the posterior to anterior chamber.

Adult↗
PubMed2000

Detection of solid pigment in dermatoscopy images using texture analysis.

BACKGROUND/AIMS: Epiluminescence microscopy (ELM), also known as dermoscopy or dermatoscopy, is a non-invasive, in vivo technique, that permits visualization of features of pigmented melanocytic neoplasms that are not discernable by examination with the naked eye. ELM offers a completely new range of visual features. One such feature is the solid pigment, also called the blotchy pigment or dark structureless area. Our goal was to automatically detect this feature and determine whether its presence is useful in distinguishing benign from malignant pigmented lesions. METHODS: Here, a texture-based algorithm is developed for the detection of solid pigment. The factors d and a used in calculating neighboring gray level dependence matrix (NGLDM) numbers were chosen as optimum by experimentation. The algorithms are tested on a set of 37 images. A new index is presented for separation of benign and malignant lesions, based on the presence of solid pigment in the periphery. RESULTS: The NGLDM large number emphasis N2 was satisfactory for the detection of the solid pigment. Nine lesions had solid pigment detected, and among our 37 lesions, no melanoma lacked solid pigment. The index for separation of benign and malignant lesions was applied to the nine lesions. We were able to separate the benign lesions with solid pigment from the malignant lesions with the exception of only one lesion, a Spitz nevus that mimicked a malignant melanoma. CONCLUSION: Texture methods may be useful in detecting important dermatoscopy features in digitized images and a new index may be useful in separating benign from malignant lesions. Testing on a larger set of lesions is needed before further conclusions can be made.

Journal Article↗
PubMed2001

Behavior of pigment cells in gastrula-stage embryos of Hemicentrotus pulcherrimus and Scaphechinus mirabilis.

The behavior of pigment cells in sea urchin embryos, especially at the gastrula stage, is not well understood, due to the lack of an appropriate method to detect pigment cells. We found that pigment cells emanated autofluorescence when they were fixed with formalin and irradiated with ultraviolet or green light. In Hemicentrotus pulcherrimus, fluorescent pigment cells became visible at the archenteron tip at the mid-gastrula stage. The cells detached from the archenteron slightly before the initiation of secondary invagination and migrated toward the apical plate. Most pigment cells entered the apical plate. This entry site seemed to be restricted, because pigment cells could not enter the ectoderm and remained in the blastocoele at the vegetal pole side when elongation of archenteron was blocked. Pigment cells that had entered the apical plate soon began to migrate in the aboral ectoderm toward the vegetal pole. In contrast, pigment cells of Scaphechinus mirabilis embryos were first detected in the vegetal plate before the onset of gastrulation. Without entering the blastocoele, these cells began to migrate preferentially in the aboral ectoderm toward the animal pole. When the archenteron tip reached the apical plate, pigment cells had already distributed throughout the aboral ectoderm. Thus, the behavior of pigment cells was quite different between H. pulcherrimus and S. mirabilis.

Animals↗
PubMed1982

Thylakoid membrane biogenesis in Chlamydomonas reinhardtii 137+. II. Cell-cycle variations in the synthesis and assembly of pigment.

Synthesis of the chlorophyll and the major carotenoid pigments and their assembly into thylakoid membrane have been studied throughout the 12-h light/12-h dark vegetative cell cycle of synchronous Chlamydomonas reinhardtii 137+ (wild-type). Pulse exposure of cells to radioactive acetate under conditions in which labeling accurately reflects lipogenesis, followed by cellular fractionation to purify thylakoid membrane, allowed direct analysis of the pigment synthesis and assembly attendant to thylakoid biogenesis. All pigments are synthesized and assembled into thylakoids continuously, but differentially, with respect to cell-cycle time. Highest synthesis and assembly rates are confined to the photoperiod (mid-to-late G1) and support chlorophyll and carotenoid accretion before M-phase. The lower levels at which these processes take place during the dark period (S, M, and early-to-mid G1) have been ascribed to pigment turnover. Within this general periodic pattern, pigment synthesis and assembly occur in a "multi-step" manner, i.e., by a temporally-ordered, stepwise integration of the various pigments into the thylakoid membrane matrix. The cell-cycle kinetics of pigment assembly at the subcellular level mirror the kinetics of pigment synthesis at the cellular level, indicating that pigment synthesis not only provides chlorophyll and carotenoid for thylakoid biogenesis but may also serve as a critical rate-determinant to pigment assembly.

Carotenoids↗
PubMed1993

Visual pigment bleaching in isolated salamander retinal cones. Microspectrophotometry and light adaptation.

Visual pigment bleaching desensitizes rod photoreceptors greatly in excess of that due to loss of quantum catch. Whether this phenomenon also occurs in cone photoreceptors was investigated for isolated salamander red-sensitive cones. In parallel experiments, (a) visual pigment depletion by steps of bleaching light was measured by microspectrophotometry, and (b) flash sensitivity was measured by recording light-sensitive membrane current. In isolated cones, visual pigment bleaching permanently reduced flash sensitivity significantly below that due to the reduction in quantum catch, and there was little spontaneous recovery of visual pigment. The "extra" desensitization due to bleaching was most prominent up to bleaches of approximately 80% visual pigment and reached a level approximately 1 log unit beyond that due to loss of quantum catch. At higher bleaches, the effect of loss of quantum catch became more important. Bleaching did not greatly reduce the maximum light-suppressible membrane current. A 99% reduction of the visual pigment permanently reduced the circulating current by only 30%. Visual pigment bleaching speeded up the kinetics of dim flash responses. All electrical effects of bleaching were reversed on exposure to 11-cis retinal, which probably caused visual pigment regeneration. Light adaptation in photopic vision is known to involve significant visual pigment depletion. The present results indicate that cones operate with a maintained circulating current even after a large pigment depletion. It is shown how Weber/Fechner behavior may still be observed in photopic vision when the contributions of bleaching to adaptation are included.

Absorptiometry, Photon↗
PubMed2006

Evaluation of dermoscopic and histopathologic features and their correlations in pigmented basal cell carcinomas.

BACKGROUND: Because of their clinical similarities, pigmented basal cell carcinomas (BCCs) can be confused with melanocytic pigmented lesions especially with melanoma. Since special dermoscopic features have been described for pigmented BCCs, dermoscopy is accepted as a useful tool for the diagnosis of pigmented BCCs. OBJECTIVE: To investigate dermoscopic and corresponding histopathologic features of BCCs and to evaluate their correlations in pigmented BCCs. METHODS: In this study, 32 pigmented BCCs in 30 patients whose diagnoses were confirmed with clinical and histopathologic features were included. Before the histopathologic evaluation, the lesions were analysed for dermoscopic features. Histopathologic correlations of dermoscopic features of BCCs and the localization of pigment accumulation in tumour mass were investigated. RESULTS: In addition to ulceration, large grey-blue ovoid nests, multiple grey-blue globules, maple leaf areas and arborizing telangiectasia; dermoscopically yellow-brown, whitish-yellow, and black-dark brown colour showed statistically significant correlation with their histopathologic counterparts (P < 0.05). Whitish veil, which is among dermoscopic features of BCCs, did not show significant correlation with its histopathologic counterpart (P > 0.05). It was histopathologically determined that pigmentation is found within the tumour mass as well as in the tumour stroma and in the hyperplastic epidermal melanocytes. CONCLUSIONS: Ulceration, large grey-blue ovoid nests, multiple grey-blue globules, maple leaf-like areas and arborizing telangiectasia, which are specific dermoscopic features for the diagnosis of pigmented BCC, were found to correlate with their histopathologic counterparts. In conclusion, dermoscopy can be described as a valuable tool for the diagnosis of pigmented basal cell carcinomas.

Aged↗
PubMed2004

Down-regulated PAR-2 is associated in part with interrupted melanosome transfer in pigmented basal cell epithelioma.

In pigmented basal cell epithelioma (BCE), there seems to be an abnormal transfer of melanized melanosomes from proliferating melanocytes to basaloid tumor cells. In this study, the interruption of that melanosome transfer was studied with special respect to the altered function of a phagocytic receptor, protease-activated receptor (PAR)-2 in the basaloid tumor cells. We used electron microscopy to clarify the disrupted transfer at the ultrastructural level and then performed immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) to examine the regulation of a phagocytic receptor, PAR-2, expressed on basaloid tumor cells. Electron microscopic analysis revealed that basaloid tumor cells of pigmented BCE have a significantly lower population of melanosomes ( approximately 16.4%) than do normal keratinocytes located in the perilesional normal epidermis ( approximately 91.0%). In contrast, in pigmented seborrheic keratosis (SK), a similarly pigmented epidermal tumor, the distribution of melanin granules does not differ between the lesional ( approximately 93.9%) and the perilesional normal epidermis ( approximately 92.2 %), indicating that interrupted melanosome transfer occurs in BCE but not in all pigmented epithelial tumors. RT-PCR analysis demonstrated that the expression of PAR-2 mRNA transcripts in basaloid cells is significantly decreased in pigmented BCE compared with the perilesional normal epidermis. In contrast, in pigmented SK, where melanosome transfer to basaloid tumor cells is not interrupted, the expression of PAR-2 mRNA transcripts is comparable between the basaloid tumor cells and the perilesional normal epidermis. Immunohistochemistry demonstrated that basaloid cells in pigmented BCE have less immunostaining for PAR-2 than do keratinocytes in the perilesional normal epidermis whereas in pigmented SK, there is no difference in immunostaining for PAR-2 between the basaloid tumor and the perilesional normal epidermis. These findings suggest that the decreased expression of PAR-2 in the basaloid cells is associated in part with the observed interruption of melanosome transfer in pigmented BCE.

Aged↗
PubMed2006

Association of kinesin and myosin with pigment granules in crustacean chromatophores.

Chromatic adaptation in crustaceans results from the differential distribution of colored pigment granules within their chromatophores consequent to cell signaling by neurosecretory peptides. However, the force transducing, mechanochemical protein motors responsible for granule translocation, and their molecular mechanisms of action, are not well understood. The present study uses immunocytochemical techniques and a motility assay in vitro to demonstrate that protein motors from the kinesin and myosin superfamilies are stably associated with membrane-bounded pigment granules in the red, ovarian chromatophores of the freshwater, palaemonid shrimp, Macrobrachium olfersii. Monoclonal antibodies against conventional kinesin heavy chain, and an anti-myosin whole serum, labeled pigment-containing fragments prepared from homogenates of chromatophores with fully dispersed or aggregated pigments: this finding infers a permanent association between the protein motors and the pigment granules, and suggests that such motors may be regulated while bound to their cargos. The pigment aggregator appears to be a myosin since the anti-myosin whole serum attenuated hormonally triggered pigment aggregation in the motility assay in vitro, and induced pigment hyper-dispersion in some chromatophores. Western blots of the chromatophore-containing, ovarian tissue homogenate demonstrated protein bands consistent with myosin II and myosin XII, either of which may be the pigment aggregator. This study provides the first direct evidence for myosin and kinesin protein motors directly and stably associated with pigment granules in crustacean chromatophores, and may represent the first successful isolation of myosin class XII.

Animals↗
PubMed2002

Visual pigment coexpression in Guinea pig cones: a microspectrophotometric study.

PURPOSE: To determine the visual pigment content of the rods and cones of the guinea pig (Cavia porcellus) and to quantify the level of coexpression of pigments within individual cones. METHODS: Microspectrophotometry was used to measure the absorbance spectrum of visual pigments in individual rods and cones from three retinal regions: dorsal, ventral, and a subequatorial transition zone. Partial bleaching was used to establish whether two spectrally distinct visual pigments were present within a single cone. RESULTS: Rods possessed a pigment with a wavelength of maximum absorbance (lambda(max)) close to 500 nm. A population of middle-wave-sensitive cones (M cones) contained a pigment with lambda(max) at approximately 530 nm, and a short-wave-sensitive cone population (S cones) contained a pigment with lambda(max) close to 400 nm. The majority of cones in all regions were M cones. Approximately 10% of cones in the transition region were found to coexpress the M and S cone pigments in a ratio of approximately 4:1. Coexpression was not detected in S cones. CONCLUSIONS: In C. porcellus, coexpression of cone pigments occurs in a small number of cells but is biased in favor of the M pigment. Given the relatively low level of coexpression, detectable in only approximately 10% of the cones in the transition region, it is unlikely to cause any significant detriment to dichromatic color vision.

Animals↗
PubMedDate not supplied

Incidence of a latanoprost-induced increase in iris pigmentation in Japanese eyes.

PURPOSE: To prospectively determine the incidence of a latanoprost-induced increase in iris pigmentation in Japanese brown iris eyes by identifying changes in iris pigmentation on a series of iris color photographs. METHODS: In a cohort study, we prospectively and consecutively enrolled 104 patients (104 eyes) with primary open-angle glaucoma or normal-tension glaucoma who began treatment with latanoprost eye drops for the first time. None of the enrolled patients had a history of previous intraocular surgery or laser surgery. Patients comprised 51 men and 53 women. Their ages ranged from 23 to 80 years (mean +/- SD, 63.8 +/- 10.4 years). Before and every 3 months after starting latanoprost treatment, iris photographs were taken using a slit-lamp biomicroscope with an attached camera. To identify an increase in iris pigmentation, seven glaucoma specialists independently read the series of photographs. If five of the seven observers agreed that iris pigmentation had increased, we determined that the iris pigmentation had increased from the time the previous photograph was taken. Ten normal volunteers served as controls, and photographs of their eyes were used in the evaluation of iris pigmentation. The Kaplan-Meier life table analysis was adopted to evaluate the incidence of increase in iris pigmentation during treatment with latanoprost. RESULTS: The Kaplan-Meier life table analysis indicated that the incidence of increased iris pigmentation at 3, 6, 9, 12, and 15 months after the start of latanoprost treatment was 16.3%, 34.2%, 49.5%, 58.2%, and 58.2%, respectively. CONCLUSIONS: Latanoprost instillation for at least 1 year induced increased iris pigmentation in approximately 50% of the treated Japanese eyes, which is a considerably higher percentage than that reported in Caucasians.

Adult↗
PubMed2001

Upregulation of pigment epithelium-derived factor after laser photocoagulation.

PURPOSE: To determine the changes in the expression of pigment epithelium-derived factor in cultured human retinal pigment epithelial cells and rat retinas after laser photocoagulation. METHODS: Experimental study of laser photocoagulation on human retinal pigment epithelial cells in culture and on adult rats. Reverse transcription-polymerase chain reaction and semiquantitative polymerase chain reaction analysis were used. RESULTS: After photocoagulation, the mRNA expression of pigment epithelium-derived factor was upregulated in human retinal pigment epithelial cells at 6 hours and then gradually decreased. Compared with controls, significantly higher levels of pigment epithelium-derived factor were observed in rat retinas from 6 to 24 hours after laser photocoagulation (P <.005), and they were still higher than before photocoagulation at 2 weeks. CONCLUSION: An upregulation of pigment epithelium-derived factor in retinal pigment epithelial cells and in the retina after photocoagulation suggests that pigment epithelium-derived factor plays a role in inhibiting neovascularization by its antiangiogenic activity.

Animals↗
PubMed1953

Some properties of a photodynamic pigment from Blepharisma.

1. A pigment can be extracted from Blepharisma undulans by heat treatment of a concentrated suspension of the deeply pigmented animals. 2. In the presence of this pigment, various colorless protozoans are sensitized to light and killed if exposed long enough. The protozoans show a differential sensitivity, some being much more sensitive than others. 3. Bleached colorless blepharismas are not sensitized to their own pigment even after prolonged exposure in the most concentrated solutions available. 4. Blepharisma is also less sensitive than any of the protozoans tested to such photodynamic dyes as rose bengal. 5. The pigment is not extracted from wet blepharismas by non-polar solvents, but is readily extracted into such polar organic solvents as the alcohols. 6. When the alcohol extract is dried, the amorphous residue is readily soluble in a variety of organic solvents, but not in the most non-polar. 7. The pigment is highly stable in alcohol extract and has been kept in the dark for years. 8. The pigment is bleached by light in a photooxidation. 9. Absorption maxima are found at wave lengths 5800, 5400, 4800, and 3300 A, the latter being the largest. Similar peaks are found in alcohol and water solutions, although the heights are not exactly the same. In both alcoholic and aqueous solutions pH had an effect on the absorption spectrum. Heat has little effect but illumination with intense visible light or exposure to ultraviolet light bleaches the pigment with decreases in the characteristic peaks. 10. Preliminary absorption column experiments indicate a single pigment in the alcohol extract. 11. Experiments on the migration of zoopurpurin in agar and gelatin gels indicate that it diffuses at about the same rate as eosin and is therefore probably not a large molecule.

Animals↗