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Results for “Microscopy, Ultraviolet”

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PubMed1993

[Electron microscopic study of erythrocyte form after extracorporeal ultraviolet and red coherent irradiation of blood].

The results of these experiments demonstrate that extracorporeal ultraviolet and red coherent blood irradiation make the energetics of erythrocyte membrane broken. This deviation has been manifested in changing of erythrocyte's form. The degree of these disorders and of inertia of the recovering process of the erythrocyte's form was greater under ultraviolet blood irradiation.

Animals↗
PubMed1985

Fluorescence of damaged myocardium in endomyocardial biopsy specimens for the evaluation of cardiac transplantation.

Sections stained with hematoxylin-eosin from 138 endomyocardial biopsy specimens were examined in a Zeiss epifluorescent ultraviolet microscope for fluorescence indicative of myocardial injury. The biopsy specimens had been obtained from cardiac transplant recipients for routine follow-up evaluation or due to clinically suspected episodes of rejection. Yellow fluorescence and/or granularity of necrotic myofibers (with normal myocardium appearing olive green to yellow-brown), as reported in autopsy series, was observed in 22 of our specimens, for which the results of staining with hematoxylin-eosin and/or trichrome were found to contain areas of fiber fluorescence that were not recognized by staining with hematoxylin-eosin or trichrome. In some areas in an additional 13 specimens, the fiber damage seen on ultraviolet examination was greater than that suspected on the basis of the light microscopic morphologic changes. In seven cases routine light microscopy revealed fiber necrosis that could not be confirmed by ultraviolet illumination study. Fluorescence of damaged myofibers under ultraviolet illumination may contribute to the detection of early or mild myocardial injury in endomyocardial biopsy specimens from cardiac transplant recipients.

Biopsy↗
PubMed1982

Changes of the cornea endothelium after ultraviolet radiation.

The rabbit cornea endothelium has been studied with specular and scanning electron microscopy after exposure with a commercially available ultraviolet lamp. The animals were plased 50 cm from the source, and most experiments were run with a 20 min exposure time. In the specular microscope, the endothelium revealed numerous circumscript reflex-free areas, which were observed from 4 days up to 8 months after the irradiation. A wide variety of changes were found in the scanning electron microscope. One day after the exposure the cells showed indistinct outlines, and they were bulging into the anterior chamber. In some regions the pattern was dominated by marked grooves preferentially along the cell demarcations, whereas other regions showed rough surfaced cells because of cytoplasmic projections and grainy deposits. At the 3 days stage there was a marked pleomorphy, and some cells were on their way to being rejected. After one week the cobblestone appearance of the endothelium was about to decline. Partly rejected cells were still common. In addition, distinct, ringshaped local impressions occurred imitating the previous described grooves. This phenomenon along with some single endothelial cells studied with microvilli were the abnormal findings 8 months after the damage. It is concluded that although ultraviolet radiation is largely absorbed in the cornea, the threshold dose for damage of the endothelium is not beyond those used for practical purpose. The endothelium was surprisingly resistant towards repeated radiation damage.

Animals↗
PubMed1992

An immunofluorescence study of the effects of ultraviolet radiation on the organization of microfilaments, keratin intermediate filaments, and microtubules in human keratinocytes.

Indirect immunofluorescence microscopy has been used to investigate the ultraviolet (UV) radiation induced disruption of the organization of microfilaments, keratin intermediate filaments, and microtubules in cultured human epidermal keratinocytes. Following irradiation, concurrent changes in the organization of the three major cytoskeletal components were observed in cells incubated under low Ca2+ (0.15 mM) conditions. UV irradiation induced a dose-dependent condensation of keratin filaments into the perinuclear region. This collapse of the keratin network was accompanied by the reorganization of microfilaments into rings and a restricted distribution of microtubules, responses normally elicited by exposure to high Ca2+ (1.05 mM) medium. The UV induced alteration of the keratin network appears to disrupt the interactions between keratin and actin, permitting the reorganization of actin filaments in the absence of Ca2+ stimulation. In addition to the perinuclear condensation of keratin filaments, UV irradiation inhibits the Ca2+ induced formation of keratin alignments at the membrane of apposed cells if UV treatment precedes exposure to high Ca2+ medium. Incubation of keratinocytes in high Ca2+ medium for 24 hours prior to irradiation results in the stabilization of membrane associated keratin alignments and a reduced susceptibility of cytoplasmic keratin filaments to UV induced disruption. Unlike results from investigations with isogenic skin fibroblasts, no UV induced disassembly of microtubules was discernible in irradiated human keratinocytes.

Actin Cytoskeleton↗
PubMed1984

Lesions induced in DNA by ultraviolet light are repaired at the nuclear cage.

In mammalian cells, S-phase DNA synthesis occurs at sites fixed to a sub-nuclear structure, the nuclear matrix or cage. This is an ordered network of non-histone proteins, which maintains its essential morphology even in the absence of DNA. We show here that unscheduled DNA synthesis following exposure of HeLa cells to ultraviolet light also takes place at this sub-structure. We also show that ultraviolet irradiation grossly reorganizes nuclear DNA, arresting S-phase synthesis at the cage and leaving the residual synthesis highly localized.

Autoradiography↗
PubMed1999

Methoxybutropate microencapsulation by gelatin-acacia complex coacervation.

Microcapsules of methoxybutropate solid particles or of an oily saturated solution of the same drug were prepared by complex coacervation between gelatin and acacia and dried with three different methods: isopropanol addition, spray-drying, and freeze-drying. Successively, microparticles were analyzed by infrared thermobalance, ultraviolet (UV) spectroscopy, optical and scanning electron microscopy, and sieves to find out parameters such as yield, moisture content, encapsulation percentage, morphology of solid particles, and particle size. Results highlighted that the most appropriate drying method for industrial purposes was spray-drying, particularly for oil-containing microcapsule formulations.

2-Propanol↗
PubMed1981

Ultraviolet light depletes surface markers of Langerhans cells.

This report defines the influence of ultraviolet light (UV) on Langerhans cells (LC). Human volunteers and hairless mice (Swiss ha/ha) were exposed to various single and/or cumulative doses of either UV-A, UV-B, or UV-A plus small amounts of UV-B (UV-A (+B)). 24 hr after the last irradiation, morphology of the entire epidermis was evaluated by both light and electron microscopy while LC, in addition, were tested for expression of specific histochemical (ATPase) and functional immunological markers (Ia antigens). In both men and mice, cumulative doses of either 80-120 J/cm2 UV-A (+B) or 1-2 X 100 J/cm2 UV-A resulted in a dramatic reduction of cells exhibiting ATPase and Ia-reactivity. In the UV-B spectrum, single doses of 60-80 mJ/cm2 produced a virtually complete elimination of LC membrane markers. By contrast, pemphigus antigens of keratinocytes were unaffected by these energy doses. Electron microscopy revealed cellular damage of some LC after UV-doses which produce a virtually complete abolition of LC membrane markers. At certain dose ranges (15-30 mJ/cm2 UV-B and 1 x 40 to 2 x 100 J/cm2 UV-A) LC were the only epidermal cells to display morphological damage at the ultrastructural level whereas higher doses affected all epidermal cells. The finding that LC surface markers and to a lesser extent the cells themselves are particularly susceptible to UV irradiation has important implications in view of previous findings that LC are potent stimulators of antigen-specific and allogeneic T cell activation. UV-induced alteration of LC plasma membrane integrity may represent a tool to manipulate adverse immune reactions involving the epidermis.

Adenosine Triphosphatases↗
PubMed1969

Ultraviolet micrography of penetration of exogenous cytochrome c into the yeast cell.

Candida utilis and Saccharomyces cerevisiae in water suspension were found to be very sensitive to exogenous cytochrome c. The protein was taken up by the cells, and the viable count was reduced to a few per cent of the initial value. Micrography at 405 nm revealed penetration of cytochrome c into the interior of the cell. The cytoplasmic membrane lost its capacity to retain intracellular constituents, and ultraviolet-absorbing compounds were released into the medium. When budding cells were subjected to treatment with cytochrome c, the mother cells were found to be more susceptible than the buds. Phosphate buffer protected the cells and spheroplasts against cytochrome c.

Candida↗
PubMedDate not supplied

In vitro exposure of murine macrophages to ultraviolet light induces apoptosis.

Ultraviolet light is a known exogenous stimuli with the ability to activate cell death by apoptosis. This study was done to examine the biologic effects of different energy levels of short wavelength UV light on cultured mouse macrophages. Cell proliferation, DNA content, and cellular ultrastructural architecture analysis demonstrated that ultraviolet light induces apoptosis in murine macrophages in culture. Exposure to 0.12J/cm2 evokes progressive cell demise with the classical features associated with apoptosis, whereas exposure to 5.0 J/cm2 results in extensive DNA degradation and crosslinking of cellular proteins. These two phenotypes are qualitatively described.

Animals↗
PubMed2005

Photopatterning of actin filament structures.

We report a general strategy for spatiotemporal control of actin polymerization in vitro using photoactivatable actin. Caged actin was synthesized by chemically modified lysine residues on monomeric actin and released with focused ultraviolet (UV) illumination. Epifluorescence microscopy revealed nucleation and elongation of individual actin filaments (8 nm in diameter) after localized release of caged actin. We also used this strategy to generate branched filament structures by releasing caged actin in the presence of actin binding proteins. Controlled self-assembly of actin filaments represents a versatile "bottom-up" technique for constructing structural building blocks and functional templates for nanoscience applications.

Actin Cytoskeleton↗
PubMed2002

UVA light in vivo reaches the nucleus of the guinea pig lens and produces deleterious, oxidative effects.

The possible role of ultraviolet light in the formation of cataract is not well understood. In this study, guinea pigs were exposed to a chronic, low level of UVA light (0.5 mWcm(-2), 340-410 nm wavelength, peak at 365 nm) for 4-5 months. It is known that the lens of the guinea pig possesses unusually high levels of the UVA chromophore NADPH. In a preliminary analysis, it was found that isolated guinea pig corneas transmitted 70-90% of 340-400 nm light, and that UVA radiation was able to penetrate deep into the nucleus of the guinea pig lens, where it was absorbed. Exposure of guinea pigs to UVA in vivo produced a 60% inactivation of lens epithelial catalase; however, analysis by transmission electron microscopy (TEM) showed no apparent morphological effects on either the lens epithelium or the cortex. A number of UVA-induced effects were found in the nucleus of the guinea pig lens, but were observed either not at all or to a lesser extent in the cortex. The effects included an increase in light scattering (two-fold; slit-lamp examination), distention of intercellular spaces (TEM), an increase in lipid peroxidation (30-35%; infrared spectroscopy), a decrease in GSH level (30%), an increase in protein-thiol mixed disulfide levels (80%), loss of water-soluble protein (20%), an increase in the amount of protein disulfide (two-fold; two-dimensional diagonal electrophoresis), degradation of MIP26 (15%) and loss of cytoskeletal proteins including actin, alpha- and beta- tubulin, vimentin and alpha-actinin (60-100%). The results indicate that a 4-5 month exposure of guinea pigs to a biologically relevant level of UVA light produces deleterious effects on the central region of the lenses of the animals. UVA radiation, coupled presumably with the photoreactive UVA chromophore NADPH and trace amounts of O(2) present in the lens nucleus, produced significant levels of oxidized products in the nuclear region over a five month period. The data demonstrate the potentially harmful nature of UVA light with respect to the lens, and highlight the importance of investigating a possible role for this type of radiation in the formation of human cataract.

Animals↗
PubMed1989

Ultrastructural changes in nucleoli and fibrillar centers under the effect of local ultraviolet microbeam irradiation of interphase culture cells.

As shown previously, ultraviolet (uv) microbeam irradiation of one of the two mature nucleoli within an interphase cell nucleus causes significant diminution and inactivation of the irradiated nucleolus and compensatory growth and activation of the nonirradiated one. In the present work we describe the results of an ultrastructural study of this phenomenon. The changes in the nucleoli were examined by means of complete series of ultrathin sections obtained from seven irradiated pig kidney cells. The compensatory hypertrophy of the nonirradiated nucleoli is shown to be accompanied by a nearly twofold increase in the number of fibrillar centers (FCs) and by a decrease in their linear dimensions compared with the control cells of the same ploidy. In the degraded nucleoli the number of FCs decreases, but their dimensions increase. Ultraviolet microbeam irradiation causes dramatic diminution of the dense fibrillar component within the irradiated nucleoli as well. The nucleolar capacity for compensatory hypertrophy indicates that in addition to active ribosomal genes, mature nucleoli also contain "silent" genes capable of being activated under extreme conditions to sustain the required level of rRNA synthesis. It is assumed that activation of latent ribosomal genes is accompanied by FC "fragmentation" without a considerable increase in their total volume per cell.

Animals↗
PubMed1987

Quantitative and morphologic changes of Langerhans' cells after ultraviolet A irradiation of human epidermis.

Three different surface markers (OKT6, HLA-DR, and adenosinetriphosphatase) were compared to identify Langerhans' cells, and the changes in number and morphology of these cells were studied at different intervals after irradiation of human skin by a 2.5-fold minimal erythema dose of ultraviolet A. Morphologic alteration and decreased surface-marker reactivity became evident on day 2 and were most pronounced on day 3 or day 4 (injury phase). The recovery phase started between day 4 and 1 week and was complete by 3 weeks. HLA-DR+/OKT6- (DR+T6-) cells were present at all time intervals. The ratio of these cells to the sum of DR+T6- and DR+T6+ cells was 0.3% before irradiation, reached a peak of 65.4% at day 4, and decreased to 0.6% by 3 weeks.

Adenosine Triphosphatases↗