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PubMed1979

Structure and function of the conidiospore pigments of Penicillium cyclopium.

The cell wall of mature, green condiospores of Penicillium cyclopium Westling contains at least two pigments: A green chromoprotein which is extractable by means of formic acid or liquified phenol and a black insoluble pigment. Both fractions after long term treatment with boiling conc. HCl leave black amorphous residues which, due to their chemical and physico-chemical properties, belong to the group of melanins. The chemical structure of these melanins is still unidentified. No degradation products typical for indol-type or catechol-type melanins have so far been detected. During spore maturation parallel to an increase of pigmentation (determined by remission), the melanin residue left after acid hydrolysis of spores increases. The mature, dark green spores of the wild type strain contain about 40% melanin, the yellow-green spores of the mutant aux-glu 1 about 36%. The unpigmented spores of mutant res-eth 1 possess a melanin content of only about 5%. This value is nearly the same as that found in hyphae, which in all strains are yellowish-brown. The heavily pigmented condia of the wild type strain are about 100-times less sensitive to UV-radiation compared with the unpigmented spores of the mutant res-eth 1. The reduced sensitivity indicates that, as with other microorganisms, the conidia pigments of P. cyclopium are protective components of the spores.

Cell Wall↗
PubMed1984

Cycloheptatrienylidene analog of 11-cis retinal. Formation of pigment in photoreceptor membranes.

In biochemical and electrophysiologic studies employing the bullfrog (Rana catesbeiana) and the rat, the authors examined the interaction of opsin and an 11-cis-locked analog of retinal. In previously bleached preparations of bullfrog receptor outer segments (ROS) and isolated retinas, incubation with the aldehyde form (I) of the analog leads to the appearance of a pigment that is degraded slowly by hydroxylamine but is relatively resistant to photolysis. In the ROS preparation, the analog pigment (lambda max of difference spectrum congruent to 497 nm) also forms on incubation with NADP+ and the alcohol form (II) of the analog. In vitamin A deprived rats possessing only approximately 45% of the normal complement of rhodopsin, intraperitoneal injection of II leads within 1 day to the appearance of the analog pigment in the photoreceptors, at levels representing a major fraction of the opsin initially available for pigment formation. Formation of the analog pigment appears to have no significant effect on the sensitivity of electroretinographic b-wave responses recorded from the rat eye; furthermore, administration of II appears to suppress the sensitizing activity of all-trans retinol injected 1 day later. The data are discussed in relation to other studies examining chromophore-opsin interactions and electrophysiologic changes associated with the formation of rhodopsin in situ.

Animals↗
PubMed1982

Identification of the endogenous retinoids associated with three cellular retinoid-binding proteins from bovine retina and retinal pigment epithelium.

The endogenous retinoids associated with three cellular retinoid-binding proteins from bovine retina and retinal pigment epithelium have been identified by their spectral characteristics and their co-migration with authentic retinoids on high performance liquid chromatography. All-trans-retinol is the only retinoid associated with the cellular retinol-binding protein from retina and retinal pigment epithelium. The saturation of the binding site with native ligand is 0.95 +/- 0.05 mol of retinoid/mol of protein for cellular retinol-binding protein purified from frozen and fresh retina and retinal pigment epithelium. All-trans-retinoic acid has been identified as the endogenous ligand associated with the cellular retinoic acid-binding protein of cattle retina. The saturation of the binding site of cellular retinoic acid-binding protein from frozen and fresh retina (the protein is absent in extracts of retinal pigment epithelium) is about 0.2 mol of retinoid/mol of protein, probably a minimum value due to losses of the ligand. Retinoic acid has not been detected previously in retina. Cellular retinaldehyde-binding protein from retina purifies with two endogenous ligands which cochromatograph on high performance liquid chromatography with 11-cis-retinaldehyde and 11-cis-retinol and occur in a ratio of approximately 3:1, respectively. The binding site of cellular retinaldehyde-binding protein from frozen retina is nearly fully occupied with these two ligands (saturation greater than 0.9 mol of retinoids/mol of protein). In contrast, purified cellular retinaldehyde-binding protein from retinal pigment epithelium carries only 11-cis-retinaldehyde as an endogenous ligand. The saturation of the binding site with this ligand is greater than 0.95.

Animals↗
PubMed1983

Selective pigment medium for Streptococcus agalactiae.

Increased awareness of the importance of Streptococcus agalactiae (Group B streptococcus) in neonatal morbidity and mortality has demonstrated the need for a selective and differential primary plating medium. In this report we describe a selective pigment medium containing colistin and nalidixic acid that allows presumptive identification of S. agalactiae from the primary plate, even when specimens are polymicrobic. A preliminary study compared the value of three media for pigment production by 137 known S. agalactiae strains. This was followed by a clinical laboratory trial using the best of these pigment media at an obstetric hospital in which 581 specimens from neonates, female reproductive tracts, and urinary tracts were screened. Subsequent to the clinical laboratory trial, an epidemiological investigation using the selective pigment medium was conducted on a mother/infant population. Of the 1,331 specimens screened for S. agalactiae, 75 (5.6%) were positive on 5% sheep blood agar and 79 (5.9%) were positive on the selective pigment medium.

Adult↗
PubMed1983

Localization of a pigment-containing structure near the surface of Xenopus eggs which contracts in response to calcium.

Contractions in surface structures of Xenopus eggs have been induced by application of the calcium ionophore A23187 or calcium ion. Local applications have shown that the contractile structure is present in both animal and vegetal hemispheres. It is, however, much stronger in the animal hemisphere and pigment embedded in it there defines the animal half. The injection of cytochalasin B (CB) into whole cells or the application of the antibiotic to half cells cannot prevent the induced contractions. By experimental means, the contraction of a deeper, pigment-containing structure can be uncoupled from a thin, more superficial and relatively pigment-free layer on the egg surface. By this means it has been possible to establish that the CB-resistant contraction is due, at least partially, to a structurally distinguishable layer subjacent to the outer egg cortex. Scanning and transmission electron microscopy demonstrate a dense grainy matrix near the egg surface in which pigment granules but little yolk are embedded. This structure is much thicker in the pigmented hemisphere. The presence of calcium ions in an isolation medium are shown to cause a loosening or dissolution of the structural connections between the dense, contractile structure near the surface and the cytoskeleton of the endoplasm.

Animals↗
PubMed1983

Pigments with antibiotic activity from Myxococcus coralloides.

A strain of Myxococcus coralloides produces pigments with antibiotic activity. The pigments are non-diffusible and become detectable at the beginning of the autolytic phase. Red pigments produced by vegetatively growing cells were extracted by acetone treatment. The crude extract when chromatographed yielded several fractions, two of which were active against certain Gram-positive bacteria. Both fractions were partial purified in thin layer chromatography and can be differentiated according to colour, polarity and absorption spectrum. Production of active pigments is increased by nicotine and inhibited by diphenylamine. The pigments are also compared with the antibiotic produced by this bacterium.

Anti-Bacterial Agents↗
PubMed1984

A new isolation procedure for retinal pigment epithelium.

A new isolation procedure for bovine retinal pigment epithelial cells has been developed. It is based on perfusion of the whole bovine eye via the central ophthalmic artery with a cold, buffered isotonic salt solution free of divalent cations for 15 min. The perfusion both weakens the association of the pigment epithelial cells with Bruch's membrane and the adhesion between retina and pigment epithelium. The retina then is removed carefully, after which the pigment epithelial cells are detached from the Bruch's membrane by gentle jets of buffer solution. The perfusion technique provides a high yield of intact retinal pigment epithelial cells, which show good viability in subsequent cell culture. Hence, cells isolated in this way are not only very well suited for long-term cell culture but also for direct biochemical analysis and short-term incubation studies.

Animals↗
PubMed1984

Reversible hepatic black pigmentation and enzyme alteration induced by prolonged feeding of high dose of crocin dyes in rats.

Crocin dyes, isolated from Gardenia jasminodes, did not affect hepatic function when they were orally administered to rats in a daily dose of 50 mg/kg for 8 days, but could induce acute hepatic discoloration. A high dosage of 100 mg/kg for 2 weeks could induce both hepatic damage and black pigmentation, but a lower dose of 100 mg/kg for 40 days did not. Rats fed on diet containing 1% of crocin dyes for four months were shown to have mild hepatic functional disorders and pigmentation. The black pigmentation of the liver and the acute hepatic damage associated with the discoloration were completely reversible. During the period of hepatic pigmentation caused by high dose of crocin dyes, the urine had abnormally increased porphyrin excretion and tended to display a blackish green color. The skin also appeared purplish black. The mechanism of black pigmentation seemed to correlate with the gradual accumulation of crocin dyes. In summary, the crocin dyes have a very low toxicity in rats even in high experimental dosage which would hardly happen in human practice. It is therefore suggested that the crocin dyes are safe for coloring foods.

Administration, Oral↗
PubMedDate not supplied

[Proliferative activity of the pigment epithelium and regenerating retinal cells in Ambystoma mexicanum].

Cellular sources of retinal regeneration and proliferative activity of the cells taking part in retina restoration have been studied in axolotls using 3H-thymidine. The cells of ciliary-terminal zone proved to be the main source of retinal restoration. Besides these cells, the pigmented cells of the iris inner and outer layers and pigment epithelium cells can take part in this process. Morphological stages of retinal regeneration have been established and regular changes in the level of proliferation in different zones of regenerating retina have been found with respect to the stage of retina restoration. The high level of proliferative activity of the pigment epithelium cells found soon after the operation favoured the restoration of disturbed integrity of the pigment epithelium layer, the increase of cell density in it, the elongation of the pigment epithelium layer, the formation of processes, and, sometimes, the replenishment of regenerating retina.

Ambystoma mexicanum↗
PubMed1981

Intravitreal injection of gentamicin in rabbits. Effect of inflammation and pigmentation on half-life and ocular distribution.

Most regimens for intravitreal injection of antibiotics are based on studies in normal albino rabbits. We examined the effect of two variables, infection and pigmentation, on the ocular distribution of an intravitreal injection of 50 micrograms of gentamicin in rabbit eyes. The half-life of gentamicin in the vitreous of normal pigmented rabbits after intravitreal administration was 24 hr. Antibiotic levels in cornea and aqueous reached a peak 18 hr after injection; terminal half-lives in these sites were similar to those in vitreous. With inflammation, the half-life in the vitreous was decreased to 10 hr, and there was no accumulation of drug in anterior sites. To the extent that these data are applicable to humans, they suggest that the treatment of bacterial endophthalmitis by the intravitreal route may require more frequent injections than had been recommended on the basis of studies in normal eyes. Normal pigmented and albino rabbits showed similar levels of gentamicin in the cornea, aqueous, and vitreous; however, the drug was barely detectable in iris, choroid-retina, and sclera of pigmented animals, presumably on account of an interaction with melanin-containing tissues. This effect of pigment may explain the differences in the reported thresholds for toxicity of gentamicin with intravitreal injection.

Animals↗
PubMed1978

Phagocytosis and surface morphology in cultured retinal pigment epithelial cells.

Phagocytosis of latex spheres was studied in explant cultures of retinal pigment epithelium from rabbit, calf, and rat (normal and dystrophic). Calf and rabbit pigment epithelial cells showed a "latent period" of about 12 and 17 hr, respectively, during which latex spheres were not ingested even when the cultures were pre-incubated for up to 24 hr prior to exposure. Scanning electron microscopy demonstrated a profusion of apical processes on the surface of cells from both species that was present throughout the latent period. In contrast, rat pigment epithelial cells showed no latent period and phagocytosed latex spheres after a pulse of 1 hr. It was concluded that the latent period is not common to all species and, when present, is not due to an absence of apical processes. The surfaces of normal and dystrophic pigment epithelial cells showed abundant apical processes that did not differ from each other in morphology, number, or distribution. In cells from pigmented species (calf and rat), frequent fusions were observed between latex phagosomes and melanosomes or melanin granules.

Animals↗
PubMed1981

Anti-pigment-cell factors and mucocutaneous candidiasis.

Previous reports documented the fact that some patients with mucocutaneous candidiasis and vitiligo have a complement-fixing anti-pigment-cell factor in their serum. We examined sera from seven patients with mucocutaneous candidiasis without vitiligo. Three of the seven sera contained the anti-pigment-cell factor. We suggest that these anti-pigment-cell factors, which are most probably antibodies, are not cytotoxic for pigment cells and, thus, not the cause of vitiligo. The association of vitiligo and anti-pigment-cell factors with the syndrome of mucocutaneous candidiasis implicates the immune system are a causal factor of vitiligo.

Adult↗
PubMedDate not supplied

[Spectroscopic and photochemical properties of pigments bound to proteins].

Using gel-filtration and spectral-luminescent analysis properties of artificial chlorophyll-protein and chlorine-protein complexes on the basis of human serum albumin (HSA) were analysed. It has been shown that formation of joint complexes pigments - HSA does not induce essential changes in the spectral and energetic parameters of the pigment part of the complex. A change in the rate of photosensitized reduction of methylviologen (sensitizer-pigment) was found during the variation of the relative content of the pigment mixed with HSA. An increase of the photoreaction rate during maximal filling of the protein globule with pigment molecules is explained by different pattern of incorporation of these molecules into protein matrix.

Chlorophyll↗
PubMed1981

Effect of vitamin E administration on photoreceptor outer segment and retinal pigment epithelium of vitamin E deficient rats.

The photoreceptor outer segment and retinal pigment epithelium of vitamin E deficient rats given vitamin E were studied by electron microscopy. In rats fed a vitamin E deficient diet for more than 12 months, the photoreceptor outer segment did not regenerate after the administration of 400 mg of vitamin E. The retinal pigment epithelium was filled with lipofuscin granules and contained cytoplasmic organelles such as mitochondria, ribosomes and Golgi apparatus. The microvilli of the retinal pigment epithelium were long and in contact with the outer nuclear layer cells. The photoreceptor inner segment and nucleus had almost disappeared. In rats given 400 mg of vitamin E after vitamin E deficiency for 6 months, the photoreceptor outer segment showed no vesiculation and were increased in number. However, some retinal pigment epithelial cells still contained many lipofuscin granules. In conclusion, the photoreceptor outer segment and retinal pigment epithelium can be repaired in mild vitamin E deficiency by vitamin E administration, but vitamin E cannot reproduce the photoreceptor cells in nuclei of which have been broken by severe vitamin E deficiency.

Animals↗
PubMed1981

Selective phagocytosis of liposomes by cultured RCS rat pigment epithelium.

Liposomes 0.5 to 5 micron in diameter and of various phospholipid compositions were used as a simplified model of rod outer segment membranes to examine the phagocytic mechanism of cultured explants of retinal dystrophic Royal College of Surgeons (RCS) and normal Long-Evans (LE) rat pigment epithelium. RCS pigment epithelium explants phagocytized liposomes composed of phosphatidylserine (pS) plus phosphatidylinositol (pI). However, phagocytosis was not observed in RCS pigment epithelium explants incubated with liposomes composed of phosphatidylcholine (pC) plus phosphatidylserine (pS), phosphatidylethanolamine (pE) plus phosphatidylinositol (pI), or pC + pS + pI + pE. Normal LE pigment epithelium explants phagocytized all preparations of liposomes. The ability of RCS pigment epithelium to differently phagocytize liposomes preparations of different phospholipid composition supports the idea that phospholipids in the membrane may participate in the phagocytic mechanism.

Animals↗
PubMed1981

[Two cases of skin pigmentation in association with minocycline therapy (author's transl)].

Report of two cases of skin pigmentation during minocycline therapy. Examination showed confluent blue-gray oval patches on the anterior part of the legs, occurring after ingestion of respectively 12 g and 100 g of minocycline. Microscopic examination of each case was identical and showed two lesions: increase in the amount of melanine deposition in the basal layer of the epidermis; presence of brown-black pigment at all the level of the dermis but specially near the sweet glands. This pigment was strongly positive with Perls' stain. Electron microscopic examination showed a finely granular pigment exclusively intracellular in dermis fibroblast and macrophage. This pigment seemed to contain mainly hemodiderine.

Hemosiderin↗
PubMed1981

Color reaction of sugars with cysteine. II. Pigment formation from sugars and biological materials.

Among carbohydrates, D-glucose, D-mannose, D-galactose, and glycogen yielded a previously described fluorescent pigment, reddish in alkaline medium and yellowish in acid, when heated with L-cysteine in hydrochloric acid solution. D-Fructose and some pentoses yielded other patients. Among tissue hydrolysates, liver, small intestine, brain, and spleen were found rich in the cysteine pigment but little or none was produced from skeletal muscle, blood, or urine. Among subfractions of rat liver cells, the microsomal fraction proved the richest source of the pigment in nmol/mg protein, though the total yield from the soluble fraction was comparable to that from the microsomal fraction. In the latter fraction, only ribosomal particles yielded the pigment; smooth membrane did not. The pigment yield from yeast was comparable to that from liver. Yield from Escherichia coli K-12 was about one-forth that from yeast.

Animals↗
PubMed1980

[Pigment in the neurons of some encephalic nuclei in Bos taurus].

Pigment granules without the properties of melanin are present in neurons of several districts (Nucleus ruber, Locus coeruleus, Ala cinerea) in the C.N.S. in Bos Taurus. The distinctive features of this pigment are autofluorescence, specifity of staining with Oil red O, Sudan Black and a strong P.A.S. positivity. The early pigment granules appear about at the end of the first year of life, their amount increases with age. The most rich pigment neurons are in the Nucleus ruber; in the neurons of the Substantia nigra, the pigment is very scanty also in the very old animals.

Animals↗