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PubMed1991

A dose-related curve of wound tensile strength following ultraviolet irradiation in the hairless guinea pig.

A dose-related curve of wound tensile strength was derived following exposure to three doses of predominantly UVA (Ultraviolet A) radiation (98.3% between 315 nm and 400 nm, 1.7% less than 315 nm). Forty female hairless guinea pigs were divided into four equal groups: Group 1 (controls); Group 2 (40 J[Joules]/cm2/day); Group 3 (80 J/cm2); and Group 4 (160 J/cm2). Preoperatively, the experimental groups were irradiated on alternate days for 16 weeks. Serial dorsal punch biopsies (4 mm) were taken prior to the initial exposure and subsequently at 2, 4, 8, 12, and 16 weeks and examined histologically and microscopically. Then, standard 6 cm midline dorsal surgical wounds were made and allowed to heal for 21 days. Wounds were excised and wound tensile strength was assessed. Significant decreases (p less than .05) were noted in wound tensile strength of Groups 2, 3, and 4 compared to the controls, with the decrease being directly related to the dose received. Dermal changes were noted in all irradiated groups as early as four weeks after initial UVA/B exposure. Electron microscopy revealed elastosis and disruption of collagen fibers. Prolonged exposure to radiation, predominantly in the UVA range, appears to impede wound healing in a dose-related fashion and elicits elastosis and collagen disruption.

Animals↗
PubMed1994

A confocal laser scanning microscope designed for indicators with ultraviolet excitation wavelengths.

In this paper we describe the modifications necessary to upgrade, at affordable cost, a commercially available confocal laser scanning microscope for use with ultraviolet (UV) excitation. The optical problems associated with these modifications are described in detail, and easy solutions to solve them are suggested. The optical resolution of the instrument was tested with fluorescent beads and was found to be close to diffraction limited. The light losses due to lateral chromatic aberration were assessed in a thick fluorescent specimen and were found to be comparable to those usually observed with visible light. For a more visual example of the resolution of this instrument, isolated ventricular heart muscle cells were loaded with the fluorescent Ca2+ indicator indo 1. This allowed us to visualize subcellular structural detail and to illustrate the optical sectioning capability of the UV confocal microscope when recording indo 1 emission. Dual-emission line scans were used to perform ratiometric time-resolved detection of Ca2+ transients in voltage-clamped heart muscle cells loaded with the salt form of indo 1. The system presented in this paper should significantly broaden the range of fluorescent indicators that can be used in confocal microscopy.

Animals↗
PubMed1992

Ultraviolet radiation (UVR) induces cell-surface Ro/SSA antigen expression by human keratinocytes in vitro: a possible mechanism for the UVR induction of cutaneous lupus lesions.

Antinuclear antibodies are useful markers of connective tissue disease. In this study, UVB but not UVA induced the expression of Ro/SSA antigen on keratinocyte surfaces in vitro. This expression was also found with the extractable nuclear antigens RnP and Sm, but not with single or double-stranded DNA. The expression was prevented by blocking protein synthesis, suggesting that it was an active process. The results suggest that UVB exposure may result in the expression of Ro/SSA antigen on the surfaces of basal keratinocytes in vivo. This antigen could then bind circulating antibody leading to the cutaneous lesions in neonatal and subacute cutaneous lupus erythematosus.

Antigens, Surface↗
PubMed1985

Inactivation of the Hutchinson strain of non-A, non-B hepatitis virus by combined use of beta-propiolactone and ultraviolet irradiation.

A beta-propiolactone/ultraviolet irradiation procedure (beta PL/UV) has been evaluated for its ability to inactivate 30,000 chimpanzee infectious doses of the Hutchinson strain of non-A, non-B (NANB) virus. The chimpanzees were inoculated with plasma to which this dose of the titrated virus had been added prior to application of the beta PL/UV process in accordance with a procedure used for licensed blood derivatives in Germany. Neither animal developed hepatitis. When subsequently challenged with the same contaminated plasma, which had not been sterilized, both animals promptly developed typical NANB hepatitis. This study extends the high (approximately 10(7)-fold) process efficiency of the beta PL/UV procedure previously reported for hepatitis B virus to a blood-borne NANB virus.

Animals↗
PubMed2000

Kinesin participates in melanosomal movement along melanocyte dendrites.

Movement of melanosomes along melanocyte dendrites is necessary for the transfer of melanin pigment from melanocytes to basal and suprabasal keratinocytes, an event critical to epidermal photoprotection and maintenance of normal skin color. Recent murine data suggest that in melanocyte dendrites the microtubule-associated melanosome movement is bidirectional and that actin-associated myosin V secures the peripheral melanosomes, preparing them to be transferred to surrounding keratinocytes. We now report that human melanocytes express high levels of kinesin, a molecule that participates in microtubule-associated transport of organelles in other cell types, and that ultrastructurally kinesin molecules are closely associated with melanosomes. To determine whether kinesin participates in melanosomal transport, cultured melanocytes were treated with sense or antisense oligonucleotides complementary to kinesin heavy chain sequences. Antisense oligonucleotides decreased kinesin protein levels and inhibited the bidirectional movement of the melanosomes, promoting their backward movement. Furthermore, guinea pigs were exposed to ultraviolet B irradiation, known to enhance transport of melanosomes from melanocytes to epidermal keratinocytes, and then were treated with kinesin sense or antisense oligonucleotides. The areas that were treated with kinesin antisense oligonucleotides showed significantly less pigmentation clinically and histologically than control (sense) oligonucleotide-treated areas. As observed ultrastructurally, in antisense-treated areas melanosomes remained in melanocyte dendrites but over several days were not transferred to the surrounding keratinocytes. Our study supports a major role for kinesin in microtubule-associated anterograde melanosomal transport in human melanocyte dendrites.

Animals↗
PubMed1984

Spindle microtubule dynamics following ultraviolet-microbeam irradiations of mitotic diatoms.

Lesions ("ARBs") generated in metaphase and anaphase central spindles of Hantzschia by an ultraviolet microbeam are devoid of microtubules previously present. In vivo, the poleward transverse edge of the lesion invariably loses birefringence poleward, until this segment has vanished; the loss is slow during metaphase and faster at anaphase. The other transverse edge, proximal to the overlap, remains stable until disassembly of the whole spindle. We conclude that the central spindle microtubules are not in flux during metaphase to telophase, and that depolymerization of these microtubules takes place only from the end distal to the pole, as during normal spindle disassembly. Microtubule polarity and the creation of free ends may determine which microtubules are disassembled during later mitosis and how disassembly proceeds.

Anaphase↗
PubMed1988

Ultraviolet microbeam irradiation of chromosomal spindle fibres shears microtubules and permits study of the new free ends in vivo.

Irradiation of birefringent chromosomal spindle fibres in crane-fly spermatocytes in metaphase I or anaphase I produces an area of reduced birefringence (ARB) on the fibre. This ARB moves poleward and is lost at the pole. Ultrastructural and immunofluorescence analysis of ARBs obtained by irradiation with monochromatic ultraviolet light of wavelength 260 nm shows that the microtubules in the irradiated area are depolymerized, though the rest of the spindle appears unaffected. The area of microtubule depolymerization moves poleward with the ARB, and once the ARB reaches the pole the irradiated half-spindle appears normal. The motion of the ARB, therefore, appears to be due to the behaviour of the sheared microtubules in the chromosomal spindle fibre. The relative stability of the sheared microtubules shows that chromosomal fibre microtubules are not dynamically unstable, as are microtubules under certain conditions in vitro. However, ARB motion may be due to a moderated version of dynamic instability. Possible models for ARB motion are discussed.

Animals↗
PubMed1992

Photosensitization of human bladder carcinoma cells by pyrene-dodecanoic acid: quantitative analysis of the cytotoxicity.

The effects of photochemotherapy with the fluorescent fatty acid pyrenedodecanoic acid (P12) and long-wavelength ultraviolet (UVA) light on cells derived from human bladder carcinoma were studied. Exposure of these anchorage-dependent cells to P12 either in monolayers of adherent cells or in suspension resulted in a time-related uptake of P12 and its incorporation into the cells' neutral and phospholipids. The uptake and localization of P12 was visualized with fluorescence microscopy and the distribution of the cell population with respect to P12 uptake was analyzed by flow cytometry. Irradiation of P12-containing monolayers of bladder carcinoma cells with UVA light resulted in cell killing. But, on microscopic examination no apparent cell lysis was detected, and since digestion with trypsin did not result in the dispersion of the monolayers it was impossible to assess toxicity by cell count. Alternative procedures were therefore used, and the following cell parameters were determined: (a) cellular uptake or release of chromate; (b) ability of cells to re-adhere to the substratum; and (c) the long-range proliferation potential. The combined inhibitory effect of photoirradiation on cell adherence and on their proliferative potential was utilized for determining reductions of up to 7 log in cell viability. The results obtained with five independently established in vitro bladder carcinoma cell lines indicated that these cells are susceptible to P12-induced photosensitization, suggesting that bladder malignancies might be potential candidates for pyrene-induced photochemotherapy.

Carcinoma↗
PubMed2000

Microwave-assisted extraction by fast sample preparation for the systematic analysis of additives in polyolefins by high-performance liquid chromatography.

This paper presents a new approach for complete and systematic analysis of organic additives in polyolefins. The proposed procedure is a convenient combination of sample preparation, performed by microwave-assisted extraction (MAE), and direct chromatographic evaluation of extract by high-performance liquid chromatography coupled with ultraviolet and evaporative light scattering detection. In particular two microwave-assisted processes are reported and discussed: the one-step MAE, useful for additives with low-medium dipolarity (like stabilizers, flame retardant, antistatics, slip and processing agents), and the two-step MAE, useful for additives with either high dipolarity (like organic salts, antigasfading, antiacid, nucleating agent) or high molecular mass (like polymeric hindered amine light stabilizers). Both the proposed processes have been tested on representative additives in five commercially common polymeric matrices, demonstrating their satisfactory analytical results, in terms of repeatability and percentage recoveries, and their good performances, in terms of safety and time/solvent consumption, in comparison with those of traditional extraction methods.

Alkenes↗
PubMed2003

Nanostructure predicts intraspecific variation in ultraviolet-blue plumage colour.

Evidence suggests that structural plumage colour can be an honest signal of individual quality, but the mechanisms responsible for the variation in expression of structural coloration within a species have not been identified. We used full-spectrum spectrometry and transmission electron microscopy to investigate the effect of variation in the nanostructure of the spongy layer on expression of structural ultraviolet (UV)-blue coloration in eastern bluebird (Sialia sialis) feathers. Fourier analysis revealed that feather nanostructure was highly organized but did not accurately predict variation in hue. Within the spongy layer of feather barbs, the number of circular keratin rods significantly predicted UV-violet chroma, whereas the standard error of the diameter of these rods significantly predicted spectral saturation. These observations show that the precision of nanostructural arrangement determines some colour variation in feathers.

Animals↗
PubMed1991

Solid state ultraviolet laser (213 nm) ablation of the cornea and synthetic collagen lenticules.

We used a Q-switched Nd:YAG laser with non-linear optical crystals to produce the 5th (213 nm) and the 4th (266 nm) harmonic frequencies. Using these two wavelengths, we ablated fresh porcine corneas and type I collagen synthetic epikeratoplasty lenticules. For the 213-nm ablation, radiant exposure was 1.3 J/cm2. The ablation rate was 0.23 micron per pulse for the epikeratoplasty lenticules. We examined all tissues with light microscopy, transmission electron microscopy, and scanning electron microscopy. Histology for the 213-nm ablation showed a clean ablation crater with minimal collagen lamellae disruption and a damage zone less than 1 micron. In comparison, the 266 nm radiation showed more charring at the edges with a damage zone approximately 25 microns deep with disruption of the stromal lamella. Our results show that this solid state UV laser is a potential alternative to the excimer laser for cornea surgery.

Aluminum Silicates↗
PubMed1994

Biologic characteristics of cultured human vitiligo melanocytes.

BACKGROUND: Vitiligo is a pigmentary disorder of unknown cause characterized by depigmented patches due to destruction of melanocytes. Recently, the inherent cellular defect theory has been discussed. To investigate the biologic characteristics of cultured melanocytes from normal and vitiligo subjects, this study had the purpose to examine the functional and ultrastructural characteristics of these melanocytes and to observe the morphologic and functional changes of melanocytes in response to ultraviolet B irradiation. METHODS: Melanocytes were isolated and cultured from foreskin and arm skin of normal and vitiligo subjects. The DNA synthesis, tyrosinase activity assay, transmission and scanning electron microscopic examination, and the effects of ultraviolet B(UVB)-irradiation on cultured melanocytes were studied. RESULTS: Vitiligo melanocytes showed no significant differences in DNA synthesis and tyrosinase activity compared with normal melanocytes, but the vitiligo melanocytes contained dilated and/or circular rough endoplasmic reticulum (RER) on transmission electron microscopic examination. Exposure of the cultured melanocytes to UVB resulted in increased protein synthesis and tyrosinase activity. Morphologic alterations and changes in DNA synthesis were also noted. Compared with normal melanocytes, the responses of vitiligo melanocyte to UVB showed no significant difference. CONCLUSIONS: Normal and vitiligo melanocytes showed similar biologic characteristics except in the changes of RERs in the vitiligo melanocytes. The ultrastructural aberrations in vitiligo subjects do not seem to be directly related to the biologic characteristics and the responses to UVB irradiation in vitiligo melanocytes.

Cell Division↗
PubMed2004

Induction of haploid androgenesis in Pacific oyster by UV irradiation.

Androgenesis, development from paternal but not maternal chromosomes, can be induced in some organisms including fish, but has not been induced previously in mollusk. In this study we investigated the induction of haploid androgenesis in the Pacific oyster by ultraviolet irradiation and observed nuclear behavior in the androgenetic eggs. Irradiation for 90 seconds at a UV intensity of 72 erg/mm2 per second (6480 erg/mm2) was the optimal dose to achieve haploid androgenesis. The fertilization and development rates of D-shaped larvae decreased with increasing exposure time, and the development of the genetically inactivated eggs terminated before reaching the D-shaped stage. Cytologic observations showed that UV irradiation did not affect germinal vesicle breakdown or chromosomal condensation but caused various nuclear behavioral patterns during meiosis and first mitosis: 21.7% of eggs extruded all maternal chromosomes as 2 or 3 polar bodies, and 59.1% of eggs formed one female pronucleus. The maternally derived nucleus did not participate, or partially participated, in the first karyokinesis. The cytologic evidence demonstrates that the male genome is directing development in haploids produced by UV irradiation.

Animals↗
PubMed1998

Efficacy of micronized titanium dioxide-containing compounds in protection against UVB-induced immunosuppression in humans in vivo.

Micronized pigment-containing sunscreens may provide a good alternative to chemical sunscreens in protection against ultraviolet (UV) B-induced immunosuppression. The metal particles in these products are likely to remain on the skin surface where they can offer broadband protection for both the UVA and UVB regions. We have tested the protective capacity of three titanium dioxide (TiO2)-containing compounds in humans in vivo. The effect on sunburn cell formation has been investigated using transmission electron microscopy, while the mixed epidermal cell lymphocyte reaction (MECLR) has been used as a model for immunosuppression. Furthermore, the influence of titanium on the integrity of the stratum corneum barrier (intercellular lipids and desmosomes) has been examined using freeze fracture electron microscopy. We find that all three compounds protect against sunburn cell formation. The immunoprotection studies show that one of the three compounds does not prevent UVB-induced changes of the MECLR responses. Application of this compound without subsequent UVB irradiation also induces a significant decrease of the MECLR responses. Moreover, the same compound affects the intercellular lipid layers, and desmosomes cannot be detected. The deleterious effect of this compound is probably caused by an incomplete hydrolysis during the TiO2 synthesis. Our findings indicate that micronized pigment-containing compounds can offer good protection against short-term UVB-induced immunomodulation in humans in vivo. However, accurate screening of the synthesis of these compounds is a prerequisite for their safe use as sunscreening agents in human subjects.

Freeze Fracturing↗
PubMed2005

Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 1: Identification and characterization.

In the Italian western Alps, asbestos mineralization (both chrysotile and tremolite amphibole) takes place from serpentinites, together with other less common asbestiform minerals not regulated by the current legislation. In the context of a study on the evaluation of the asbestos risk in this area, the possible role played by the associated asbestiform minerals in the overall toxicity of the airborne fraction has been examined. The first mineral investigated was balangeroite [(Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)36], an iron-rich asbestiform contaminant of chrysotile from the Balangero mine (Piedmont), which crystallizes as rigid and brittle fibers. In order to prepare a sample in a form appropriate for chemical and cellular tests, the fibers were separated from the rock and comminuted without damage to their crystalline structure and surface state (as confirmed by X-ray diffraction [XRD] and ultraviolet-visible [UV-Vis] spectroscopy). The first properties examined were durability in simulated body fluids (Gamble's solution) and toxicity to epithelial cells. When compared to UICC crocidolite (the amphibole blue asbestos, regarded as the most pathogenic form), balangeroite appears even more durable than crocidolite. Balangeroite and UICC crocidolite showed a similar in vitro cytotoxic effect on a human epithelial cell line, as evidenced by leakage of intracellular lactate dehydrogenase (LDH) activity, which, observed after a 24-h incubation, was dose dependent and maximal at 12 microg/cm2 for each fiber type. Data show that chemical composition, form, durability, and cell toxicity indicate balangeroite as a potentially harmful fibrous mineral that needs to be examined by further chemical and cellular tests.

Asbestos, Serpentine↗
PubMed2003

In vivo UVB irradiation induces clustering of Fas (CD95) on human epidermal cells.

In vitro studies with human cell lines have demonstrated that the death receptor Fas plays a role in ultraviolet (UV)-induced apoptosis. The purpose of the present study was to investigate the relation between Fas expression and apoptosis as well as clustering of Fas in human epidermis after a single dose of UVB irradiation. Normal healthy individuals were irradiated with three minimal erythema doses (MED) of UVB on forearm or buttock skin. Suction blisters from unirradiated and irradiated skin were raised, and Fas, FasL, and apoptosis of epidermal cells quantified by flow cytometry. Clustering of Fas was from skin biopsied. Soluble FasL in suction blister fluid was quantified by ELISA. Flow cytometric analysis demonstrated increased expression intensity of Fas after irradiation, with 1.6-,2.2- and 2.7-fold increased median expression at 24, 48 and 72 h after irradiation, respectively (n=4). Apoptosis was demonstrated by the TUNEL reaction, and the maximum of apoptotic cells was detected at 48 h after irradiation. Double-staining of Fas and TUNEL showed that apoptosis was restricted to the Fas-positive epidermal subpopulation, but there was no correlation between the intensities of Fas expression and TUNEL reaction. Median expression intensity of FasL-positive cells transiently decreased to 0.9- and 0.8-fold of the preirradiation respective level after 24 h and 48 h, respectively, and returned to the respective preirradiation level at 72 h after irradiation (n=4). Concentrations of soluble FasL in suction blister fluid from UVB-irradiated skin did not differ from those in unirradiated skin (n=5). Confocal laser scanning microscopy showed a rapid clustering of Fas within 30 min after irradiation. A simultaneous clustering of the adapter signalling protein FADD suggested that Fas clustering has a functional significance. Our results ar in accordance with previous findings from in vitro studies, and suggest that Fas is activated in vivo in human epidermis after UVB exposure.

Adult↗