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PubMed2004

Retinal temperature increase during transpupillary thermotherapy: effects of pigmentation, subretinal blood, and choroidal blood flow.

PURPOSE: To study the risk of adverse events in transpupillary thermotherapy (TTT) for age-related macular degeneration by measuring how laser-induced retinal temperature increase is affected experimentally by subretinal blood, choroidal blood flow, and chorioretinal pigmentation. METHODS: An ultrafine thermocouple technique was developed to measure retinal temperature increase during TTT in albino and pigmented rabbit eyes. TTT was performed with 60-second, 0.78-mm spot size, 810-nm infrared diode laser exposures with power settings ranging from 50 to 950 mW. Intraretinal and subretinal temperature increases were measured in pigmented and albino rabbits, with or without subretinal blood and choroidal blood flow. RESULTS: Threshold power settings for visible lesions in albino and pigmented rabbits were 950 and 90 mW, respectively, corresponding to retinal temperature increases of 11.8 degrees C and 5.28 degrees C, respectively. Power settings required to produce threshold lesions in albino rabbits caused retinal temperature increases in pigmented rabbits that were five times higher than in the albino rabbits. Temperature increases in albino rabbits were 1.5 times higher with subretinal blood than without it. Choroidal blood flow generally did not affect measured retinal temperature increases. CONCLUSIONS: The results confirm prior theoretical recommendations that clinicians should consider decreasing TTT power settings in darkly pigmented eyes and proceed with caution in those with subretinal hemorrhage or pigment clumping.

Animals↗
PubMed2003

Absorption, distribution and excretion of 14C-chloroquine after single oral administration in albino and pigmented rats: binding characteristics of chloroquine-related radioactivity to melanin in-vivo.

Chloroquine is an antimalarial agent that has been reported to have distinct affinity to melanin. After single oral administration of 14C-chloroquine at a dose of 20mg kg-1 under non-fasting conditions, the absorption, distribution and excretion of 14C-chloroquine-related radioactivity were studied in albino and pigmented rats. The objectives of the study were to investigate differences in the disposition of chloroquine between albino and pigmented rats and to define its in-vivo binding characteristics to melanin-containing ocular tissues. Extensive uptake of radioactivity into tissues was indicated by higher concentrations in most tissues compared with serum and there was no quantitative differences in the distribution of radioactivity found between albino and pigmented rats except for melanin-containing tissues, such as the uveal tract of the eye and perhaps hair follicles. There was selective and strong binding of drug-related compounds to these tissues in pigmented rats. The uveal tract concentrations reached the maximum value of 158.42 +/- 7.86 micrograms equiv g-1 (mean+/-s.e.) at 1 week and decreased very slowly with a terminal half life of 4476 h (187 day). The uveal tract concentrations at 24 weeks were still high (67.75 +/- 6.19 micrograms equiv g-1). The AUC for uveal tract was 842.3 mg.h g-1. A relatively high concentration was still determined in the uveal tract even at 48 weeks after single oral dosing by whole-body autoradiography. The uveal tracts separated from one eye of each rat were extracted with 0.067 M phosphate buffer (pH 7.4) and 1 M HCl-EtOH (30:70) successively. In pigmented rats, almost all radioactivity was released from the tissue with 1 M HCl-EtOH (30:70), indicating that the strong binding by melanin was reversible, and that hydrophobic or electrostatic interaction would play a critical role in the binding of chloroquine and its metabolites with the melanin-containing ocular tissues. Approximately 70% of the radioactivity given was recovered in urine and faeces up to 144 h after dosing both in pigmented and albino rats. The excretion pattern in pigmented rats was similar to that seen in albino rats.

Administration, Oral↗
PubMed1987

Polarized pigment granule transport occurs in the absence of microtubules in squirrelfish erythrophores: studies of the effects of estramustine.

We have re-examined the involvement of microtubules in the process of pigment granule transport in squirrelfish erythrophores in situ (i.e. on scales). Light-microscopic studies revealed that following exposure to 5 microM-nocodazole for 1 h at 4 degrees C erythrophores retained an ability to aggregate and disperse their pigment uniformly, though at reduced rates. Serial thick-section stereo high-voltage electron-microscopic studies showed that the entire microtubule population was removed by drug treatment and that the microtubules were not reassembled as a result of pigment translocation processes in the presence of reduced levels of nocodazole (0.4 microM). Immunofluorescence microscopic studies confirmed that nocodazole (0.5-1 microM) produced rapid disassembly of the microtubules. Whole-mount electron-microscopic studies showed that the pigment granules were suspended in a cross-linking network of 3-10 nm filaments, which appeared to support ordered pigment transport in situ in the absence of microtubules. Drug inhibition studies showed that micromolar levels of estramustine, a novel anti-MAPs (microtubule-associated proteins) drug, reversibly inhibited pigment transport. The results suggest that an estramustine-sensitive cytomatrix component might produce polarized pigment transport in intact erythrophores.

Animals↗
PubMed1983

Lipofuscin Pigment In Adult Clonorchis Sinensis.

Adult Clonorchis sinensis from infected human cases may have black pigment in their parenchyme. In present paper, the nature of the pigment was investigated. The pigment distributed in cytoplasm of parenchymal cells of the worms. Histochemically the pigment was positive by periodic acid-Schiff, Ziehl-Neelsen, and lipofuscin stainings. The pigment particle contained many, various sized membrane structure as well as electron dense granules when observed by electron microscopy. Staining characteristics of the black pigment, together with electron microscopic findings, strongly indicated that the pigment was lipofuscin.

Journal Article↗
PubMed1999

Paradoxical response to dexamethasone in the diagnosis of primary pigmented nodular adrenocortical disease.

BACKGROUND: Primary pigmented nodular adrenocortical disease causes the Cushing syndrome in children and young adults and is most frequently associated with the Carney complex. OBJECTIVE: To evaluate diagnostic tests for primary pigmented nodular adrenocortical disease. DESIGN: Retrospective cohort study. SETTING: Tertiary care center. PATIENTS: 21 patients with primary pigmented nodular adrenocortical disease. The control groups consisted of 9 patients with macronodular adrenocortical disease and 15 patients with primary unilateral adrenocortical disease (single adenomas). MEASUREMENTS: Clinical characteristics, radiologic imaging, and a 6-day Liddle test with determination of urinary free cortisol and 17-hydroxycorticosteroid excretion. RESULTS: Adrenal imaging and other tests were of limited value for the diagnosis of primary pigmented nodular adrenocortical disease. The Liddle test, however, distinguished patients with this disorder from those with other primary adrenocortical lesions. An increase of 50% or more in urinary free cortisol levels on day 6 of the Liddle test identified 9 of 13 patients (69.2% [95% CI, 46.6% to 91.8%]) with primary pigmented nodular adrenocortical disease, excluded all patients with macronodular adrenocortical disease, and was present in only 3 of the 15 patients with single adrenocortical adenomas (20% [CI, 0% to 40.2%]). An increase in urinary free cortisol excretion of 100% or more on day 6 of the Liddle test identified only patients with primary pigmented nodular adrenocortical disease. CONCLUSIONS: Patients with primary pigmented nodular adrenocortical disease responded to dexamethasone with a paradoxical increase in glucocorticoid excretion during the Liddle test. This feature distinguishes such patients from those who have the Cushing syndrome caused by other primary adrenal disorders and may lead to timely detection of the Carney complex (a potentially fatal disorder) in asymptomatic patients.

17-Hydroxycorticosteroids↗
PubMed1999

Tradition of pigment cell research at Charles University in Prague.

A short review on the history of pigment cell research at Charles University (Ch.U.) in Prague is presented. The famous Czech physiologist and professor J.E. Purkyne started the pigment cell research at Ch.U. already in 1837. He discovered melanin granules in the cells of substantia nigra of the brain. Later, in 1858, a Czech professor of medicine at Ch.U., B. Eiselt, as the first, described melanogenuria in 3 patients with generalized melanoma. Also some German professors at Ch.U. contributed to the research of melanins and melanogenuria in the past, especially H. Waelsch (1932). After the World War II, a Czech professor of medical chemistry at Ch.U., A.F. Richter with his young assistant J. Duchon continued in the chemical exploration of melanins (1954) and J.D. with Z. Pechan, B. Matous and S. Pavel devoted their attention to melanogenuria in melanoma patients (1962-1980). In 1967 they identified 2 new metabolites in melanoma urine: 5-hydroxy-6-methoxy and 6-hydroxy-5-methoxy-indole-2-carboxylic acids. J. Duchon with J. Borovanský and P. Hach also studied morphology and chemical composition of different melanosomes (1972-1979) and brought the first evidence that melanosomes consist of several proteins (1972). In 1980's 4 groups devoted to the pigment cell research and originated from Ch.U. were formed. The groups of J.B., of B.M. and of J. Vachtenheim in Prague and the group of S.P. who moved to the Netherlands (Leiden). As for the clinical aspects of the pigment cell research, the s.c. Hermanský-Pudlák syndrome published in 1959 and the histopathological classification of malignant melanomas estimated by J. Trapl (1957), should be mentioned. Therefore it is not surprising that, as a result of the tradition of pigment cell research at Ch.U., the 3rd European Workshop on Melanin Pigmentation was held in Prague already in 1981 and that, in 1998 again, Ch.U. was entrusted with the arrangement of the 8th Meeting of the European Society for Pigment Cell Research at the occasion of the Ch.U. 650th anniversary.

Biochemistry↗
PubMed2001

Mucin gene expression in gallbladder epithelium with black pigment stone ascertained by in situ hybridization.

Black pigment stones are usually found in patients with liver cirrhosis or hemolytic disease. Mucoglycoproteins are present in a significant amount in black pigment stones and contribute to the matrix of gallstones. Epithelium of stone-containing gallbladders contains much more mucin than those without stones. In this study, we try to determine by in situ hybridization the mucin gene expression in black stone-containing gallbladders and try to find the diversity of mucin gene expression in gallbladders containing black pigment stones and those without stones. In situ hybridization with DIG-tailed oligonucleotides was performed on sections of paraffin-embedded tissues of gallbladders with black pigment stones (n = 10) and those without stones (n = 6) to identify the expression of MUC1, MUC2, MUC3, MUC4, MUC5B and MUC6 in gallbladder epithelium. The findings showed that (1) mRNA expression of MUC1, MUC3, MUC5B and MUC6 were found in all gallbladders with black pigment stones, while they were expressed in 33.3%, 83.3%, 83.3% and 66.7% respectively in those without stones. They were expressed more strongly and extensively in gallbladders with stones when compared to those without stones. (2) MUC2 and MUC4 labeling were absent in gallbladders without stones, while they were present in 20% and 60% of gallbladders with black pigment stones, respectively. We conclude that MUC3, MUC5B and MUC6 were the main mucin gene expression in either gallbladder with or without stones. Altered mucin gene expression occurred in gallbladders with black pigment stones, such as the presence of MUC2 and MUC4 and increased expression of MUC1, MUC3, MUC5B and MUC6 in black stone-containing gallbladders. The higher incidence and stronger labeling intensity of mucin gene expression of MUC2, MUC3, MUC5B and MUC6 in black stone-containing gallbladder may reflect abundant mucin content in these gallbladders. Increased expression of MUC2 and MUC4 in black stone-containing gallbladder epithelium indicated that intestinal metaplasia and altered mucin genes could occur in diseased gallbladders.

Adult↗
PubMed2003

Differential effects of endothelin-1 on calcium mobility in cultured porcine pigment epithelial cells of iris and retina.

BACKGROUND AND PURPOSE: Photoreceptor function depends on an intact retina pigment epithelial (RPE) cell layer. Transplantation of iris pigment epithelial (IPE) cells to the subretinal space offers a potential alternative to RPE transplantation in patients with severe retinal diseases such as macular degeneration. Whether the functions of IPE and RPE are similar or different is not well established. The purpose of this study was to identify the characteristics of IPE cells and RPE cells by detecting the effects of endothelin-1 (ET-1) on intracellular free Ca(2+) ([Ca(2+)](i)) mobility in these cells. METHODS: Iris and retina pigment epithelial cells were cultured from porcine eyeballs. After the cells were loaded with fura-2/AM, fluorescence was monitored with a fluorescent spectrophotometer by continuously recording excitation signals at 340 nm and 380 nm and emission signals at 510 nm. RESULTS: IPE and RPE cells induced a significant increase in [Ca(2+)](i) under exposure to 10(-7), 10(-8), and 10(-9) mol/L ET-1 in Ca(2+)-containing buffer. In the presence of Ca(2+)-free buffer, ET-1 alone induced an increase in [Ca(2+)](i) in iris but not in retina pigment epithelial cells. In Ca(2+)-free buffer, pretreatment of the IPE cells with 10(-7) mol/L ET-1 partially inhibited thapsigargin-induced [Ca(2+)](i) increase and carbonylcyanide m-chlorophenylhydrazone (CCCP)-induced Ca(2+) release. Similarly, pretreatment of the IPE cells with thapsigargin or CCCP also partially inhibited ET-1-induced [Ca(2+)](i) increase. The [Ca(2+)](i) release induced by 10(-7) mol/L ET-1 was not inhibited by the phospholipase C inhibitor U73122. In Ca(2+)-containing buffer, the ET(A) receptor antagonist BQ123 and ET(B) receptor antagonist BQ788 partially inhibited 10(-7) mol/L ET-1-induced [Ca(2+)](i) increase in IPE cells. However, BQ123 partially inhibited the 10(-7) mol/L ET-1-induced [Ca(2+)](i) increase in RPE cells. Nifedipine partially inhibited 10(-7) mol/L ET-1-induced [Ca(2+)](i) increase in both types of pigment cells. CONCLUSIONS: These results suggest that iris and retina pigment epithelial cells possess distinguishing characteristics because the ET-1-induced [Ca(2+)](i) increases in these 2 types of pigment epithelial cells are regulated by distinct mechanisms.

Animals↗
PubMed2004

Genetics and epigenetics in flower pigmentation associated with transposable elements in morning glories.

Among the genus Ipomoea, three morning glories, I. nil the Japanese morning glory), I. purpurea (the common morning glory), and I. tricolor, were domesticated well for floricultural plants, and many spontaneous mutants displaying various flower pigmentation patterns were isolated. Most of these spontaneous mutations were found to be caused by the insertion of DNA transposable elements in the genes for the anthocyanin pigmentation in flowers, and many of them exhibited variegated flowers, such as white flowers with pigmented spots and sectors. Here, we describe the historical background of the mutants displaying variegated flowers and review the genetic and epigenetic regulation in flower pigmentation associated with transposable elements of these morning glories. The flecked, speckled, r-1, and purple mutations in I. nil were caused by insertions of Tpnl and its relatives in the En/Spm superfamily, Tpn2, Tpn3, and Tpn4, into the genes for anthocyanin coloration in flowers,i.e., DFR-B, CHI, CHS-D, and InNHXI, respectively. Similarly, the flaked and pink mutants of I. purpurea have distantly related elements, Tip100 and Tip201, in the Ac/Ds superfamily inserted into the CHS-D and F3'H genes, respectively. The flower variegation patterns can be determined by the frequency and timing of the excision of these transposons, and their stable insertions produce plain color flowers without generating pigmented spots or sectors; furthermore, both genetic and epigenetic regulation appeared to play important roles in determining the frequency and timing of the excision of the transposons. However, flower variegation is not always associated with the excision of an integrated DNA transposon from one of the genes for anthocyanin pigmentation. The mutant Flying Saucers of I. tricolor displaying variegated flowers was found to have the transposon ItMULE inserted into the DFR-B promoter region, but no excision of ITMULEL from the DFR-B could be detected in the variegated flower lines. The instable pearly-vrg allele in cv. Flying Saucers is likely to be an epiallele because the DNA methylation in the DFR-B promoter appeared to be associated with flower pigmentation.

Journal Article↗
PubMedDate not supplied

[Mutant gene expression in mouse aggregation chimeras. 8. The effect of the white gene on coat pigmentation].

Aggregation of mouse embryos produced 11 chimaeras Miwh/+C/C----+/+c/c and 8 chimaeras +/+C/C----+/+c/c (control). Chimaerism was detected by mosaicism of coat retinal pigment epithelium and by electrophoretic pattern of glucose phosphate isomerase. All chimaeras showed a common pattern of pigmented and unpigmented hair regions that alternated as stripes of different length and width and extended from spine in lateral-ventral direction. However, white coat color predominated in Miwh/+C/C----+/+c/c chimaeras due to a higher proportion of unpigmented zones as well as to weakening of hair color in pigmented areas. Besides, distal regions of limbs were always unpigmented in Miwh/+C/C----+/+c/c chimaeras and completely or partially pigmented in +/+C/C----+/+c/c chimaeras. Pigmented hair regions are often located on the ventral trunk surface where the Miwh/+ heterozygotes usually had an unpigmented spot. The examination of hairs, taken from the same regions of gray coloration, revealed the presence of pigmented, unpigmented and mosaic hairs. The proportion of unpigmented hairs was much higher in Miwh/+C/C----+/+c/c chimaeras than in +/+C/C----+/+c/c chimaeras. The data obtained indicate that a single Miwh gene dose reduced proliferative activity of melanoblasts which resulted in weakening of coat pigmentation.

Alleles↗
PubMed1994

Cloning of the human DOPAchrome tautomerase/tyrosinase-related protein 2 gene and identification of two regulatory regions required for its pigment cell-specific expression.

We have cloned and sequenced the human genomic DNA segments encoding the 5'-flanking region and the first two exons of the DOPAchrome tautomerase (DT)/tyrosinase-related protein 2 (TRP-2) gene. The DT gene is a member of the tyrosinase gene family and specifically expressed in melanin-producing cells. A transcriptional initiation site of the DT gene was identified by S1 nuclease-mapping and primer-extension analyses using RNA prepared from human pigmented melanoma cells. To study the mechanism for pigment cell-specific expression of the human DT gene, we analyzed the promoter function of its 5'-flanking region by transient expression assays. The fusion genes, containing the DT gene promoter upstream from a firefly luciferase reporter gene, were introduced into human pigmented melanoma cells and HeLa cells, and the pigment cell-specific promoter activity was evaluated by comparing the luciferase activity expressed in both cell lines. A series of 5' deletion studies of the human DT gene promoter revealed that the 32-bp element, located between -447 and -415, is sufficient to confer pigment cell-specific expression of a reporter gene on a homologous promoter, but not on a heterologous simian virus 40 promoter. Internal deletion studies using a homologous or a heterologous promoter revealed that the pigment cell-specific expression of a reporter gene mediated by the 32-bp element is dependent on the presence of another region of the DT gene spanning from -268 to -56, which was termed the proximal region. However, the proximal region by itself is not sufficient to confer cell type-specific expression. These results indicate that the presence of two regulatory regions, the 32-bp element and the proximal region, is required for pigment cell-specific expression of the DT gene. Both regulatory regions contain a CANNTG motif, a well known binding site for a large family of transcription factors possessing a basic helix-loop-helix structure.

Base Sequence↗
PubMed1975

Congenital grouped pigmentation of the retina. Histopathologic description and report of a case.

Gross examination of an eye removed at autopsy from a 4-year-old child with congenital heart disease revealed typical grouped pigmentation of the retina. Routine light microscopy and flat preparation of the retinal pigment epithelium demonstrated the lesions to consist of focal areas of increased concentration of pigment granules in otherwise normal retinal pigment epithelial cells. The pigment granules were large and football shaped. The overlying photoreceptors showed no abnormalities, possibly explaining the clinical features of normal visual acuity and visual fields in this patient. We believe that this is the first histologic description of congenital grouped pigmentation reported in the English literature. A differential diagnosis and brief review of the pertinent literature are also presented.

Child, Preschool↗
PubMed1983

Dimensions of the anterior chamber in pigment dispersion syndrome.

A recently introduced theory of the mechanism of the pigment dispersion syndrome is that pigment granules are released by mechanical contact between the anterior surface of zonular fibrils and the posterior surface of the pigment epithelium of the iris. A photogrammetric study of the depth of the central and peripheral anterior chamber of the iris was carried out in 37 subjects with the pigment dispersion syndrome. These subjects had deeper anterior chambers, particularly in the midperiphery, than could be accounted for by their age, sex, or refractive error. Excessive depth of the anterior chamber is demonstrated to be a risk factor in the pigment dispersion syndrome. Concavity of the midperipheral iris surface was demonstrated in this group of subjects, confirming previous clinical observations and giving additional support to the mechanical theory of pigment dispersion.

Adult↗
PubMed1995

Pigment variant of neuronal ceroid-lipofuscinosis.

A 6-year-old girl had progressive ataxia, and visual disturbances resulting in blindness. She died in her sleep at age 22 years. She shared with her sister and paternal relatives bilateral pes cavus deformities and impaired deep-tendon reflexes which suggested Charcot-Marie-Tooth disease. Her sister, who also had both polyneuropathy and a progressive central nervous system (CNS) disease, did not have pigmentary retinopathy. At autopsy, the patient was found to have neuronal ceroid-lipofuscinosis (NCL) marked by intraneuronal accumulation of autofluorescent granular lipopigments in ballooned perikarya and conspicuous extraneuronal pigmentation of subcortical grey matter, but without axonal spheroids. These findings indicate a pigment variant of NCL and represent one of very few patients recorded. The ultrastructure of the intraneuronal pigments was uniformly granular, while that of the extraneuronal pigments found within processes of the neuropil and glial perikarya was more variegated. In addition to those patients with the pigment variant of NCL, described earlier by Jakob and Kolkmann [1973: Acta Neuropathol (Berl) 26:225-236], and Jervis and Pullarkat [1978: Neurology 28:500-503], our patient shared clinical symptoms with those described in a family afflicted with polyneuropathy and NCL by Wisniewski et al. [1987: J Child Neurol 2:33-41]. Currently, it is unclear whether they have similar atypical forms of juvenile NCL (JNCL). We conclude that the spectrum of pigment variants in lysosomal diseases is heterogeneous: only few and recently described patients have had NCL, while others most likely had other forms of lipidosis.

Cerebral Cortex↗
PubMed1985

The optokinetic nystagmus and ocular pigmentation of hypopigmented mouse mutants.

We tested the optokinetic nystagmus (OKN) reflex of various hypopigmented mutant mice and ultrastructurally examined the pigmentation of various ocular structures in these mutants. Using electron microscopy we examined the pigmentation of the choroid and retinal pigment epithelium (RPE) and measured the numerical density, volume density, and distribution of RPE melanosomes of mice with the following phenotypes: (1) wild type, (2) mutants that have abnormal or no OKN in response to horizontally moving, full-field stimulation, and (3) other mutants that have normal OKN but reduced choroidal pigmentation. We also measured the OKN of all these mice in response to horizontally moving stimuli that were restricted to the nasal or to the temporal retina. We found that in the mutants with normal OKN the numerical density of melanosomes in the RPE was within the range found for wild type, while the numerical density was reduced for the mutants with abnormal OKN. For one mutant with normal RPE pigmentation and normal OKN, the choroidal pigmentation was nearly absent. For the genotypes with abnormal OKN the volume density of the RPE melanosomes and percent apical melanosomes were sometimes greater and sometimes less than normal. The OKN patterns of these mice fell into the following categories: (1) wild type; (2) field-restriction dependent OKN with small following movements but no OKN in response to full-field stimulation, normal OKN in response to stimulation of the nasal retina, and OKN of reversed direction in response to stimulation of the temporal retina; (3) oblique with slow oblique following movements and reduced numbers of OKNs with oblique quick phases in response to horizontally moving, full-field stimulation, nearly normal OKN in response to stimulation of the nasal retina, and OKN of reversed direction in response to stimulation of the temporal retina. The horizontal component of the oblique response to full-field stimulation was in the same direction for the two eyes, but the vertical component was in the opposite direction. (4) Slow, small amplitude, with no or very small following movements in response to full-field stimulation, following movements in response to stimulation of the nasal retina and reversed "following" movements in response to stimulation of the temporal retina but few or no quick phases of the OKN for any stimulus condition. These results show that a variety of abnormalities of the OKN occur for hypopigmentation mutants of the mouse.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

UV irradiation causes multiple cellular changes in cultured human retinal pigment epithelium cells.

BACKGROUND: The retinal pigment epithelium maybe causally involved in the development and progression of age-related macula degeneration; however, the mechanisms leading to the development of age-related macula degeneration remain largely unknown. The purpose of this study was to examine cellular changes in the retinal pigment epithelium induced by direct irradiation with UV light in culture. METHODS: Retinal pigment epithelium cells from post-mortem human retinas were used to obtain dissociated cultures with cells retaining the ability to differentiate in vitro. These cells were cultured over several days to weeks. The UV radiation (UV-A and UV-B) occurred under sterile conditions with a 100 HBO/mercury bulb attached to a dissecting microscope, delivering co-axial illumination. The time dependence of irradiation effects was analysed using morphometric, immunohistochemical, functional and apoptosis-detecting techniques. RESULTS: Vital and proliferating retinal pigment epithelium cell cultures could be prepared consistently. The cells showed tissue-specific morphologies in vitro for several days to weeks. Pigment epithelium-derived factor was detected in these cells using immunocytochemistry and Western blots. The UV irradiation but not white light resulted in measurable alterations of cell shape and size. The irradiated cells showed partial swelling and shrinkage reminiscent of progressing apoptotic degeneration. TUNEL staining revealed that apoptosis was induced by UV light, but not detectably by white light. The phagocytosis of fluorescent micro-particles diminished after irradiation. These effects were dependent on the duration of irradiation. CONCLUSIONS: Cultures of retinal pigment epithelium are suitable and sensitive models to study cell damage and may contribute to unravelling the pathogenetic mechanisms of retinal degeneration.

Apoptosis↗
PubMed1983

Effects of centrophenoxine on lipofuscin in the retinal pigment epithelium of old mice.

The effects of centrophenoxine on the retinal pigment epithelium (RPE) of 17 month old female mice have been studied. Animals were injected subcutaneously for 3 months (60 injections) with the drug (0.1 mg/g of body wt) daily in 0.1 M phosphate buffered saline at pH 7.0. The morphological changes in the pigment layers of the retina of both eyes were studied by light and electron microscopy and the lipofuscin pigment was demonstrated by its autofluorescence and ultrastructural characteristics. There was a significant reduction of the lipofuscin pigment in the treated animals, but the melanin pigment remained unchanged. The lipofuscin granules also appeared less osmiophilic and showed a greater preponderance of membranes and vacuoles. Although the precise mechanism of action of the drug is not clear, an increased protective function of the pigment epithelium by the drug has been suggested.

Aging↗
PubMed1984

Mitotic and pigment-translocating activities of cultured chromatophores of the guppy, Lebistes reticulatus.

Using Ham's F-12 medium, an in vitro culture system permitting cellular survival for over 6 months has been developed for the chromatophores of the guppy. In this culture system, the various types of chromatophores (melanophores, erythrophores and xanthophores) migrated out of the explanted tail fin tissue, retained their pigmentation, and displayed both mitotic and pigment-translocating activities. The mitotic activity was evident during the first 3 or 4 weeks in culture, whereas the pigment-translocating ability persisted for 16 weeks. The cultured chromatophores of male fish displayed pigment aggregation in response to adrenergic agents (epinephrine and norepinephrine) and pigment dispersion in response to alpha-melanocyte stimulating hormone (alpha-MSH), cyclic AMP and dibutyryl cyclic AMP. Cyclic GMP did not elicit pigment-translocating responses in any of the chromatophores.

Animals↗