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PubMed1984

Pharmacological characteristics of beta-adrenergic-sensitive adenylate cyclase in non pigmented and in pigmented cells of bovine ciliary process.

Adenylate cyclase activity was studied on the two epithelial cell types of bovine ciliary process after digestion by trypsin and purification by density gradient centrifugation. cAMP formation after isoproterenol stimulation showed that non pigmented cells were particularly enriched in adenylate cyclase activity. Furthermore pharmacological characteristics of this enzyme indicated that adenylate cyclase-associated beta adrenergic receptors were of beta 2 type in each kind of epithelial cells. These results support the hypothesis that beta adrenergic compounds modulate aqueous humor production through a direct effect on ciliary epithelium and enrichment of beta adrenergic sensitive adenylate cyclase activity in non pigmented epithelial cells suggests that these particular cells may play an important role in aqueous humor secretion.

Adenylyl Cyclases↗
PubMed1977

Effects of colchicine on phagosome-lysosome interaction in retinal pigment epithelium. II. In vitro observations on histio-organotypical retinal pigment epithelial cells of the pig (a preliminary report).

Phagocytic activity of histiotypical and organotypical retinal pigment epithelial cells was studied by SEM and EM. After a latent period polystyrene microspheres of different diameter were captured by newly formed microvilli. No mechanism of discrimination according to the size of microspheres was observed. After engulfment, microvilli of histiotypical cells decreased in length and finally disappeared. Lysosomes increased in number when compared to unstimulated cells and fused with many latex-containing phagosomes. Colchicine, when added at 5 X 10(-5) M to the medium, inhibits phagosome-lysome interaction, thus confirming in vivo observations.

Animals↗
PubMed1976

Photoelectrochemical effects in the electrolyte-pigment-metal system. I. Metal-free phthalocyanine film description of short-circuit photocurrents for thin films of pigment.

Using a semitransparent metallic electrode covered with a thin film of metal-free phthalocyanine, photoelectrochemical effects have been studied in the electrolyte-pigment-metal system. Measurement of the short-circuit photocurrent, produced by continuous illumination, allows description of a photodependent kinetic phase corresponding to the establishment of a stationary state in the charge separation region of the system after the creation of the current carriers.

Biological Transport↗
PubMed2004

Pigment epithelial changes in a strain of pigmented rabbits with low ERG b-wave amplitudes.

Retinas from a strain of rabbits with low dark-adapted electroretinographic (ERG) b-wave amplitudes, and declining ERG responses with time, were examined by light and electron microscopy. Seven rabbits from the affected strain (13 months to 5 years old) and six control animals (6-26 months old) were included in the study. Small inclusions with an electron dense border, about 0.2-1.5 microm in diameter, were significantly (p<0.01) more numerous within the retinal pigment epithelial (RPE) cells in the affected rabbits than in the control animals. No morphological evidence of retinal degeneration was found. Further studies are needed to establish the functional defect in this strain of rabbits.

Animals↗
PubMed2003

Retinal pigment epithelium and endothelial cell interaction causes retinal pigment epithelial barrier dysfunction via a soluble VEGF-dependent mechanism.

PURPOSE: To investigate the effect of endothelial cells (EC) on the barrier function of the retinal pigment epithelium (RPE). METHODS: Primary bovine RPE were grown in solo culture or in coculture with bovine EC. Culture media of RPE were varied to develop a monolayer with stable barrier properties determined by transepithelial electrical resistance (TER) and permeability to sodium fluorescein. The effect of EC on the barrier properties of RPE was tested in contacting and non-contacting cocultures of RPE and EC. The conditioned media of cocultures were analysed for soluble vascular endothelial growth factor (VEGF) by ELISA. A neutralizing antibody to VEGF(165) was added to cocultures of RPE and EC and the TER was measured. RESULTS: RPE had maximal barrier properties (high TER, low permeability, positive staining for barrier proteins) at day 10 that persisted until day 20. Compared to solo RPE culture, cocultivation of RPE with EC reduced RPE barrier function significantly and led to a greater release of soluble VEGF into the conditioned media (p<0.05). Neutralizing VEGF with antibody led to partial recovery of barrier properties in the coculture conditions (p<0.03). CONCLUSIONS: Coculture of RPE with EC reduces RPE barrier properties and the reduction is, in part, mediated by soluble VEGF. EC-RPE contact-induced disruption of barrier properties occurs in ocular pathologies such as choroidal neovascularization, where EC move through Bruch's membrane and contact the RPE, leading to further exacerbation of the already compromised blood-retinal barrier.

Animals↗
PubMed2000

Pigment-protein architecture in the light-harvesting antenna complexes of purple bacteria: does the crystal structure reflect the native pigment-protein arrangement?

Structural analysis of crystallized peripheral (LH2) and core antenna complexes (LH1) of purple bacteria has revealed circular aggregates of high rotational symmetry (C8, C9 and C16, respectively). Quantum-chemical calculations indicate that in particular the waterwheel-like arrangements of pigments should show characteristic structure-sensitive spectroscopic behavior in the near infrared absorption region. Laser-spectroscopic data obtained with non-crystallized, isolated LH2 of Rhodospirillum molischianum are in line with a highly symmetric (C8) circular aggregate, but deviations have been found for LH2 of Rhodobacter sphaeroides and Rhodopseudomonas acidophila. For both the latter, C-shaped incomplete circular aggregates (as seen only recently in electron micrographs of crystallized LH1-reaction center complexes) may be a suitable preliminary model.

Bacterial Proteins↗
PubMed2002

Determination of the virulence of the pigmentation-deficient and pigmentation-/plasminogen activator-deficient strains of Yersinia pestis in non-human primate and mouse models of pneumonic plague.

The current human plague vaccine, a killed Yersinia pestis whole-cell preparation, does not protect against aerosol challenge and is reactogenic and antigenically undefined. Live attenuated Y. pestis, such as pigmentation-deficient (Pgm-) strains, have been used frequently as vaccines and are efficacious. They are used widely in plague research and assumed to be safe. However, they can cause serious adverse reactions, and their aerosol infectivity is not known. We tested the virulence of a defined Pgm- variant of the C092 strain of Y. pestis in mouse and non-human primate models of pneumonic plague. The ten-fold lower median lethal dose by the aerosol compared to the subcutaneous (s.c.) routes of the Pgm- strain in mice suggested that the Pgm- strain might be less attenuated by the former than by the latter route. After exposure of 16 African green monkeys to inhaled doses ranging from 1.1 x 10(4) to 8.1 x 10(7)cfu, eight died and eight survived. The terminal cultures collected from five of the non-survivors were all positive for Y. pestis. Two of the remaining three non-survivors were culture-negative but had pathologic and immunologic evidence of infection with Y. pestis, specimens could not be obtained nor the cause of death determined for the third one. The deaths were not dose-related, and there were some differences in the pathology associated with infection by the Pgm- strain compared to the wild-type (wt) strain. However, the Pgm- derivative was clearly virulent for monkeys by the aerosol route. A mutant of the Pgm- strain, which has a deletion in the plasminogen activator (Pla) virulence locus (pla), appeared to be more attenuated than was either the Pgm- single mutant (in NHPs and mice) or the Pla- single mutant strain (in mice) and has potential as a live vaccine.

Administration, Inhalation↗
PubMed2002

Evaluation of the cytotoxicity of selected systemic and intravitreally dosed drugs in the cultures of human retinal pigment epithelial cell line and of pig primary retinal pigment epithelial cells.

The cytotoxicity of the selected systemic and intravitreally dosed drugs tamoxifen, toremifene, chloroquine, 5-fluorouracil, gentamicin and ganciclovir was studied in retinal pigment epithelium (RPE) in vitro. The cytotoxicity was assayed in the human RPE cell line D407 and the pig RPE cell culture using the WST-1 test, which is an assay of cell proliferation and viability. The effects of experimental conditions on the WST-1 test (cell density, serum content in the culture medium, the exposure time) were evaluated. The EC50 values in tamoxifen-treated D407 cells ranged between 6.7 and 8.9 micromol/l, and in pig RPE cells between 10.1 and 12.2 micromol/l, depending on the cell density used. The corresponding values for toremifene were 7.4 to 11.1 micromol/l in D407 cells and 10.0 to 11.6 micromol/l in pig RPE cells. In chloroquine-treated cells, the EC50 values were 110.0 micromol/l for D407 cells and 58.4 micromol/l for pig RPE cells. Gentamicin and ganciclovir did not show any toxicity in micromolar concentrations. The exposure time was a significant factor, especially when the drug did not induce cell death, but was antiproliferative (5-fluorouracil). Serum protected the cells from the toxic effects of the drugs. Both cell cultures were most sensitive to tamoxifen and toremifene, and next to chloroquine. The drug toxicities obtained in the present study were quite similar in both cell types; that is, the pig RPE cells and the human D 407 cell line, despite the differences in, for example, the growth rate and melanin contents of the cell types. Owing to the homeostatic functions important for the whole neuroretina, RPE is an interesting in vitro model for the evaluation of retinal toxicity, but, in addition to the WST-1 test, more specific tests and markers based on the homeostatic functions of the RPE are needed.

Animals↗
PubMed2002

Mutation analysis of Lhca1 antenna complex. Low energy absorption forms originate from pigment-pigment interactions.

The light harvesting complex Lhca1, one of the four gene products comprising the photosystem I antenna system, has been analyzed by site-directed mutagenesis with the aim of determining the chromophore(s) responsible for its long wavelength chlorophyll spectral form, a specific characteristic of the LHCI antenna complex. A family of mutant proteins, each carrying a mutation at a single chlorophyll-binding residue, was obtained and characterized by biochemical and spectroscopic methods. A map of the chromophores bound to each of the 10 chlorophyll-binding sites was drawn, and the energy levels of the Q(y) transition were determined in most cases. When compared with Lhcb proteins previously analyzed, Lhca1 is characterized by stronger interactions between individual chromophores as detected by both biochemical and spectroscopic methods; most mutations, although targeted to a single residue, lead to the loss of more than one chromophore and of conservative CD signals typical of chlorophyll-chlorophyll interactions. The lower energy absorption form (686 nm at 100K, 688 nm at room temperature), which is responsible for the red-shifted emission components at 690 and 701 nm, typical of Lhca1, is associated with a chlorophyll a/chlorophyll a excitonic interaction originating from a pigment cluster localized in the protein domain situated between helix C and the helix A/helix B cross. This cluster includes chlorophylls bound to sites A5-B5-B6 and a xanthophyll bound to site L2.

Arabidopsis Proteins↗
PubMed2002

In vivo assessment of retinal carotenoids: macular pigment detection techniques and their impact on monitoring pigment status.

Of the many carotenoids found within human tissue, only the carotenoids within the human retina can be assessed noninvasively at present. Such assessment should eventually provide a more complete understanding of the functional role of retinal lutein (L) and zeaxanthin (Z) (termed macular pigment, MP) in human vision. The emerging data allow for some initial observations. For example, there appears to be wide variation (>factor of 10) in the concentration of MP. Although MP levels have been recorded from nondetectable to 1.20 OD (optical density), the "average" levels, relative to what is possible, appear low. This may be due in part to the low average dietary intake of L and Z in the typical U.S. diet. Nonetheless, individual differences in MP may also be influenced by nondietary factors such as genetics, demographics and lifestyle characteristics. Some evidence indicates that the MP carotenoids may protect the retina and lens, and could improve vision through some optical mechanisms. Consequently, efforts to determine typical MP levels and the factors that influence individual differences in MP density should be continued.

Carotenoids↗
PubMed2006

Pigmented coalescing papules on the dorsa of the hands: pigmented colloid milium associated with exogenous ochronosis.

Colloid milium is a rare cutaneous deposition disorder that frequently occurs in areas of chronic sun exposure such as the face, neck and backs of the hands and is characterized by multiple small, discrete, usually amber-colored, dome-shaped papules that cluster to form large plaques. A 50-year-old white woman with esophageal squamous cell carcinoma was referred to us with asymptomatic, slowly spreading lesions localized to the dorsa of her hands which had been present for 4 years. The condition was diagnosed histopathologically as pigmented colloid milium associated with exogenous ochronosis (EO). Colloid milium associated with EO is very rarely reported in the published work. We think that a possible interaction between sunlight and exposure to chemical fertilizers may have played a role in the pathogenesis of both of the disorders in our case.

Carcinoma, Squamous Cell↗
PubMed1993

Characterization of pigmented granules in minocycline-induced cutaneous pigmentation: observations using fluorescence microscopy and high-performance liquid chromatography.

We describe a technique to facilitate histopathological detection and quantitative measurement of trace amounts of tissue minocycline. In a patient with minocycline-induced hyperpigmentation, a series of biopsies were taken from the affected skin over a period of 54 months, and examined for tissue minocycline deposition. Frozen sections treated with 1 M MgCl2-ethanol yielded minocycline-specific yellowish fluorescence, the location of which corresponded to clumps of granular deposits in the dermis. A decrease in the number of fluorescent granules correlated with the clinical resolution of hyperpigmentation and a significant decrease in the tissue minocycline level. Our data also provide further support for the concept that the pigment granules contain insoluble complexes of minocycline chelated with iron. The fluorescence technique is simple, sensitive, and reproducible.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

[Indices of pigment formation in complex cytomorphological research on human pigmented skin neoplasms].

Analysis of the topography peculiarities and distribution of oxidized melanine and its precursors (DOPA-oxide activity and catecholamine) in pigment nevuses and malignant melanomas of skin shows that the studied peculiarities are a complex of intersupplementary markers of melanine formation, correlate with the quality and the degree of proliferative process expression in tumours of this genesis and may be used for their malignancy rating.

Adult↗
PubMed1977

Localization of cellular retinal-binding protein in bovine retina and retinal pigment epithelium, with a consideration of the pigment epithelium isolation technique.

Bovine RPE was isolated by commonly used brushout procedures and analyzed by light and electron microscopy. The preparation was found to consist almost entirely of cells with retained organelles (mitochondria, pigment, and other granules) but with broken surface membranes and extracted cytoplasm. In keeping with this, the wash obtained by sedimenting these broken cells contained approximately 97 percent of the cellular retinol-binding protein present in the suspension. Cellular retinoic acid-binding protein, present in bovine retinal extracts, was found in low amounts in the wash from RPE. The cellular retinol-binding protein present in the RPE wash was of high specific activity and similar in properties to that obtained from bovine retina. Supernatant obtained from sonicated rod outer segments contained approximately 10 percent of the retinol-binding protein of the retina. No retinoic acid-binding protein was found. The relatively large amount of cellular retinol-binding protein present in the RPE (more than is found in the retina) is consistent with a functional role of this protein in uptake and transport of retinol by the RPE.

Animals↗
PubMedDate not supplied

[Comparative study of the energy metabolic enzymatic activity of pigmented and pigment-free strains of Serratia marcescens].

The activity of enzymes involved in energy metabolism was investigated in the pigmented strain of Serratia marcescens and in its pigmentless variant with an elevated activity of nuclease. The pigmentless strain was found to exhibit a higher specific activity of several enzymes participating in glycolysis, the pentose phosphate cycle, and the citric acid cycle. The pigmentless strain accumulated lesser amounts of lactic acid in the medium and was characterized by the negative Voges--Proskauer reaction.

Culture Media↗
PubMed1997

Draft definition of stage I pressure ulcers: inclusion of persons with darkly pigmented skin. NPUAP Task Force on Stage I Definition and Darkly Pigmented Skin.

The National Pressure Ulcer Advisory Panel appointed a task force to review the definition of Stage I pressure ulcers, specifically to assess its adequacy in people with darkly pigmented skin. The process used by the task force to draft a new definition is described in this preliminary report of their work. The proposed definition and initial critique of it are given.

Humans↗
PubMed1996

The major carotenoid pigment of a psychrotrophic Micrococcus roseus strain: fluorescence properties of the pigment and its binding to membranes.

The fluorescence excitation and emission spectra are reported for P-3 (bis-dehydro-B-carotene-2-carboxylic acid), the major carotenoid pigment of psychrotrophic M. roseus. The excitation spectrum and the absorption spectrum showed good agreement with respect to the position of their peak maxima. The study also demonstrates that P-3 binds to liposomes prepared from synthetic lipids (PC, DOPG, or CL) or the total lipids of a mutant colourless M. roseus. Binding of P-3 to the membranes was accompanied by a decrease in the fluorescence emission intensity and a blue shift in lambda(em) maximum by 15 to 20 nm. The quantum yield of P-3 was observed to be low (1.7 x 10(-5)).

Carbon Disulfide↗
PubMed2006

[Bilateral serous detachment of the neurosensory retina and retinal pigment epithelium with rip of the peripheral pigment epithelium].

HISTORY: A 52-year-old patient with atypical plasmocytoma presented with a bilateral serous detachment of the retina as well as a huge detachment of the pigment epithelium (PE) in the periphery. Shortly thereafter the PE ruptured. In the left eye this led to substantial central macular fibrosis. DIAGNOSIS: The clinically healthy patient showed a nephrotic syndrome; neither typical monoclonality was detectable nor was erythropoiesis or myelopoiesis reduced. THERAPY: To avoid further reduction of VA pars plana vitrectomy (ppV) with silicone oil tamponade and laser coagulation was performed. Clinical findings were reduced significantly and VA was stabilized for 2.5 years. DISCUSSION: PE detachments and serous retinal detachments in patients with nephrotic syndrome are only mentioned in a few cases. However, a peripheral rupture of the PE to this extent seems to be very rare. Early ppV with silicone oil and laser coagulation may prevent further macular fibrosis.

Antineoplastic Combined Chemotherapy Protocols↗