Presence Of Ultraviolet Light Research Articles

In VitroPhotogenotoxic Activity of Clinafloxacin: A Paradigm Predicting Photocarcinogenicity

Fluoroquinolone antiinfective drugs exhibit phototoxic, photogenotoxic, and photocarcinogenic activities in experimental systems which may be interrelated. Clinafloxacin (CLX), a new fluoroquinolone, is a potent antiinfective agent being developed for use in life-threatening infections. While this drug has previously been demonstrated to be phototoxic, this report evaluated the photogenotoxic and photocarcinogenic potential of CLX. When Skh-1 mice were administered CLX in the presence of ultraviolet light (UVA) at the maximum tolerated dose expected for a photocarcinogenicity bioassay, induction of DNA strand breakage was noted in keratinocytes isolated from these animals. When compared with other well-studied fluoroquinolonesin vitro,CLX and Lomefloxacin (LMX) were equally effective in producing chromosome damage and DNA strand breakage in Chinese hamster ovary (CHO) cells exposed to UVA. Treatment of CHO cells with CLX in the presence of UVA also resulted in hydroxyl radical formation. However, coincubation of CHO cells with CLX and various antioxidants markedly reduced hydroxyl radical formation, but inhibited photogenotoxicity only to a limited extent. Thus, while reactive oxygen species contribute to the photogenotoxic activity of CLX, other factors may be involved. Since CLX exhibits both phototoxic and photogenotoxic activity, we predict that CLX would be photocarcinogenicin vivo.The present study suggests that under conditions of human exposure, the potential risk for CLX-induced photocarcinogenicity is small.

Peroxidation treatment of dye manufacturing wastewater in the presence of ultraviolet light and ferrous ions

This study was performed to investigate the removal of COD and color from a dye manufacturing plant wastewater using the H 2O 2/UV/Fe 2+ process. Comparison of removal efficiencies were made among the H 2O 2/UV, the H 2O 2/Fe 2+ and the H 2O 2/UV/Fe 2+ processes. Removal of COD and color of approximately 80 and 90% can be achieved by H 2O 2/UV/Fe 2+ processes, respectively. The H 2O 2/Fe 2+ reaction is responsible for approximately 80% removal of both COD and color, the H 2O 2/UV reaction for 10%, and UV/Fe 3+ for the remaining 10%. The removal kinetics of COD and color were consistent with those of H 2O 2 and Fe 2+, respectively. Ferrous ions addition at higher dosage results in the rate of COD removal per unit dosage higher than that of color, whereas the UV irradiation favors color removal more than the COD removal, in terms of rate or rate per unit power. It appears that there is some benefit gained by multi-step addition of Fe 2+, but not H 2O 2.

Kestrels prefer scent marks according to species and reproductive status of voles

We have previously documented that European kestrels (Falco tinnunculus L.) are attracted to the scent marks of small rodents in the presence of ultraviolet light (UV) but not visible light (VL). In this paper we describe laboratory experiments used to determine if there were differences in scent marks of small rodents that could affect kestrel prey choice. In two laboratory experiments made with mixed (UV + VL) light, individual kestrels were given a choice of scent marks of different vole species, and reproductive categories. In the first experiment, kestrels preferred scent marks of mature field vole (Microtus agrestis L.) males over those of mature females or non-breeding juveniles. No difference was observed in their preference of scent marks of females and juveniles. In the second experiment, kestrels preferred scent marks left by sibling voles (Microtus rossiaemeridionalis Ognev) more than scent marks left by either field voles or bank voles (Clethrionomys glareolus Schreber). Kestrels showed no difference in preference between the scent of field voles and bank voles, or between scent marks of field voles and a control arena. Kestrels appear to be able to differentiate between vole species and reproductive categories on the basis of scent marks, which has potentially important consequence for prey choice and selection of breeding areas.

Mechanism of Action of Human P-glycoprotein ATPase Activity: PHOTOCHEMICAL CLEAVAGE DURING A CATALYTIC TRANSITION STATE USING ORTHOVANADATE REVEALS CROSS-TALK BETWEEN THE TWO ATP SITES

Human P-glycoprotein (P-gp), an ATP-dependent efflux pump responsible for cross-resistance of human cancers to a variety of lipophilic compounds, is composed of two homologous halves, each containing six transmembrane domains and an ATP-binding/utilization domain. To determine whether each site can hydrolyze ATP simultaneously, we used an orthovanadate (Vi)-induced ADP-trapping technique (P-gp.MgADP.Vi). In analogy with other ATPases, a photochemical peptide bond cleavage reaction occurs within the Walker A nucleotide binding domain consensus sequence (GX4GK(T/S)) when the molecule is trapped with Vi in an inhibited catalytic transition state (P-gp.MgADP.Vi) and incubated in the presence of ultraviolet light. Upon reconstitution into proteoliposomes, histidine-tagged purified P-gp from baculovirus-infected insect cells had drug-stimulated ATPase activity. Reconstituted P-gp was incubated with either ATP or 8-azido-ATP in the presence or absence of Vi under ultraviolet (365 nm) light on ice for 60 min. The resultant products were separated by SDS-polyacrylamide gel electrophoresis and subjected to immunoblotting with seven different human P-gp-specific antibodies covering the entire length of the molecule. Little to no degradation of P-gp was observed in the absence of Vi. In the presence of Vi, products of approximately 28, 47, 94, and 110 kDa were obtained, consistent with predicted molecular weights from cleavage at either of the ATP sites but not both sites. An additional Vi-dependent cleavage site was detected at or near the trypsin site in the linker region of P-gp. These results suggest that both the amino- and carboxyl-terminal ATP sites can hydrolyze ATP. However, there is no evidence that ATP can be hydrolyzed simultaneously by both sites.

Contribution to the study of rigid PVC polyblends with different lignins

Evaluation of different types of lignins and lignin derivatives, representing a spectrum of significant differences in regard to delignification processes and the nature of wood, in blending with a rigid poly(vinyl chloride) (PVC) compound for outdoor application is discussed. The influence of lignins on the processability of the blends, as well as on their strength at yield, break, and impact before weathering, and after 7 days of artificial weathering period (in the presence of ultraviolet light, humidity, and moderate temperature) was investigated, and the data correlated with those of rigid PVC compound. Infrared and thermal analysis were performed to elucidate the morphology of the blends. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1731–1744, 1997

Contribution to the study of rigid PVC polyblends with different lignins

Evaluation of different types of lignins and lignin derivatives, representing a spectrum of significant differences in regard to delignification processes and the nature of wood, in blending with a rigid poly(vinyl chloride) (PVC) compound for outdoor application is discussed. The influence of lignins on the processability of the blends, as well as on their strength at yield, break, and impact before weathering, and after 7 days of artificial weathering period (in the presence of ultraviolet light, humidity, and moderate temperature) was investigated, and the data correlated with those of rigid PVC compound. Infrared and thermal analysis were performed to elucidate the morphology of the blends. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1731–1744, 1997

Enzymatic recognition and biological effects of photodynamic damage induced in DNA by 1,6-dioxapyrene plus UVA

The specific recognition of DNA modifications by repair endonucleases was used to characterize DNA damage induced by 1,6-dioxapyrene (1,6-DP) in the presence of ultraviolet light at 365 nm (UVA) in the plasmid YEplac 181. Under cell free conditions, 1,6-DP plus UVA generated lesions are recognized by the UvrABC endonuclease, the proteins Nth, Nfo and Fpg. The number of UvrABC sensitive sites was at least ten-fold higher than that of Fpg or Nth sensitive sites. Moreover, 1,6-DP plus UVA generated single-strand breaks which are the second most frequent lesions. To investigate the biological effect of DNA damage, YEplac181 DNA was treated with 1,6-DP plus UVA and transformed into Escherichia coli or Saccharomyces cerevisae. In Escherichia coli, the transformation efficiency of 1,6-DP plus UVA treated DNA was greatly reduced in the uvrA mutant compared to that in the wild-type strain. However, the transforming efficiency was not affected in Fpg-deficient strains. In Saccharomyces cerevisiae, the transformation efficiency of 1,6-DP plus UVA treated YEplac181 was greatly reduced in the rad14:: URA3 strain. The photobiological effect of 1,6-DP plus UVA was also analysed in haploid yeast strains of various repair capacities. The results show that the yeast strain defective in the nucleotide excision repair pathway ( rad14:: URA3) is hypersensitive to 1,6-DP plus UVA treatment as compared to the parental wild-type strain. It is confirmed that the lethal effect of 1,6-DP plus UVA on wild-type yeast is strongly oxygen dependent, whereas the survival of the rad14:: URA3 mutant only exhibits a minor oxygen dependence. To conclude, our data show that the photodynamic DNA lesions induced by 1,6-DP plus UVA can be recognized and repaired in pro-and eukaryotic cells by the nucleotide excision repair pathway.

Remote plasma and ultraviolet–ozone modification of polystyrene

Remote argon plasma (RP) and ozone in the presence of ultraviolet light (UV–O3) were used to render polystyrene (PS) surfaces hydrophilic in a controlled manner for eventual application in cell-surface interaction studies. X-ray photoelectron spectroscopy (XPS) was used to characterize both methods of modification. The degree of modification on PS was measured by an increase in surface oxygen and concomitant change in C 1s binding energies as a function of time. Both remote plasma and UV–O3 are shown to be partially surface destructive, producing polymer fragments which are easily washed away to leave stable modified surfaces of oxidized polymer comprising of distributions of C–O, C=O and O—C=O type groups. Of the two methods, UV–O3 is shown to be more versatile and conducive to preparing PS surfaces with controllably varying degrees of modification. UV–O3 modified polystyrene is shown to be stable in air for at least eight months. Contact angle methods were used in correlation with XPS in characterizing UV–O3 modified surfaces. It is shown that changes in surface tension and total surface oxygen content were related, however, not directly connected.

Preliminary Findings of an In Vitro Assay Based on Human Complement Activation for the Detection of Chemicals with Phototoxicity Potential

Eight known photosensitising chemicals and one non-photoaensitiser were compared for their ability to activate the complement system of human serum in both the presence and the absence of ultraviolet (UV) radiation. Commercially available ELISA systems for the detection of C4d and iC3b fragments were used to investigate the classical and alternative pathways, respectively. The results indicated that, whereas the classical pathway was unaffected, all the photosensitisers tested were capable of activating the alternative pathway in the presence of UV light, and that this activation occurred at different levels, depending upon the chemical itself. The non-photosensitising chemical, sodium dodecyl sulphate, acted as a negative control. It is, therefore, suggested that this type of method could be considered for inclusion in any battery of in vitro tests designed for the detection of potential photosensitising chemicals.

Defects Introduced by Plasma Processing of Silicon

ABSTRACTThe electrical and optical properties of defects introduced by Reactive Ion Etching (RIE) in the near surface region of Si after dry etching with various gases and plasma conditions is studied with spreading Resistance (SR), photoluminescence (PL), and capacitance-voltage profiling (C-V). Plasma etching in chlorine and fluorine based gases produce donors at the surface in both n-type and p-type, Czochralski and float-zone silicon. Isochronal annealing reveals the presence of two distinct regions of dopant compensation. The surface damage region is confined to 1000 Å and survives heat treatment at 400°C, while the defect reaction region extends ≥ 1 μm in depth and recovers by 250°C. A comprehensive picture of the interstitial defect reactions in RIE silicon is completed. The interstitial defects, Ci and Bi, created in the ion damaged near surface region, undergo recombination enhanced diffusion caused by the presence of ultraviolet light in the plasma, resulting in the long range diffusion into the Si bulk. Subsequently, the interstitial atoms are trapped by the background impurities forming the defect pairs, CiOi, CSCi, or BiOi, which are observed experimentally. The depth of the diffusion-limited trapping and the probability of forming specific pairs depends on the relative concentrations of the reactants, oxygen, carbon or boron, present in the bulk material.

Superoxide dismutase—Inactivation by α-terthienyl: A novel observation in thiophene photochemistry

In order to demonstrate a photochemical inactivation of superoxide dismutase (EC 1.15.1.1) in the anal gills of mosquito larvae by α-terthienyl, a negative staining method has been applied which utilizes the reduction of nitroblue tetrazolium into a diformazan by superoxide radical and its intersection by this enzyme. The enzyme increased with the development of the larvae being minimum in the first instar and maximum in the fourth instar. Superoxide dismutase activity is inhibited by the naturally occurring thiophene α-terthienyl (2,2′:5,2″-terthiophene) in the presence of ultraviolet light, results of which are comparable with the inhibition by diethyldithiocarbamic acid, a known inhibitor of superoxide dismutase. It is suggested that the presence of superoxide dismutase in the anal gills plays some important role in providing resistance to mosquito larvae against harmful oxygen derivatives.

Effects of sulfhydryl agents, trifluoperazine, phosphatase inhibitors and tryptic proteolysis on calcineurin isolated from bovine cerebral cortex

Calcineurin was discovered as an inhibitor of calmodulin stimulated cyclic AMP phosphodiesterase and its ability to act as a calmodulin binding protein largely explains its inhibitory action on calmodulin regulated enzymes. Recent studies establish calcineurin as the enzyme protein phosphatase whose activity is regulated by calmodulin and a variety of divalent metals. In this work, we have investigated the effects of several agents including sulfhydryl agents, trifluoperazine (a calmodulin antagonist), PPi, NaF and orthovanadate and of tryptic proteolysis on the calcineurin inhibition of cyclic AMP phosphodiesterase (called inhibitory activity) and on protein phosphatase activity. Inhibitors for sulfhydryl groups (pHMB, NEM) inhibited phosphatase activity without any effect on the inhibitory activity. Dithioerythritol completely reversed the inhibition by pHMB. Limited proteolysis of calcineurin caused an activation of basal phosphatase activity with a complete loss of inhibitory activity. Phosphatase activity of the proteolyzed calcineurin was not stimulated by calmodulin. The presence of calmodulin along with calcineurin during tryptic digestion appeared to preserve the stimulation of phosphatase by Ca2(+)-calmodulin. [3H]-Trifluoperazine (TFP) was found to be incorporated irreversibly into calcineurin in the presence of ultraviolet light. This incorporation was evident into the A and B subunits of calcineurin. TFP-caused a decrease in the phosphatase activity and an increase in its inhibitory activity. [3H]-TFP incorporation into the A subunit was drastically decreased in the proteolyzed calcineurin. This was also true when the [3H]-TFP incorporated calcineurin was subjected to tryptic proteolysis. The incorporation into the B unit was essentially unaffected in the trypsinized calcineurin. Phosphatase activity was inhibited by orthovanadate, NaF, PPi, and EDTA. Inhibitions by these compounds were more pronounced when the phosphatase was determined in the presence of Ca2(+)-calmodulin than in their absence.

‘Stereovectorcardiogram’ Made by Stereolithography

A method for making directly a single solid vectorcardiogram is reported. A solid vectorcardiogram was made by employing an apparatus for production of three-dimensional objects by stereolithography. Stereolithography is a computer-aided manufacturing technique that is practiced in conjunction with computer-aided design and engineering. To design the solid vectorcardiogram, voltages in the X, Y and Z axes obtained according to the Frank lead are memorized in the computer-aided design system. By use of the stereolithography apparatus, the designed solid vectorcardiogram is formed in a vat filled with liquid plastic. In the vat, the plastic changes rapidly from liquid to solid in the presence of ultraviolet light so that a solid vectorcardiogram made of solid plastic may be formed.

Stabilized dam mar picture varnish

AbstractAlthough films of dammar resin cannot be stabilized against photochemical degradation in the presence of ultraviolet light with currently available additives, a remarkable stabilization is obtained with a hindered amine light stabilizer (HALS) if the ultraviolet component of the light source is eliminated. Even in the absence of UV light the effect of HALS can be improved by further addition of a benzotriazole ultraviolet absorber. It is proposed that the UV absorber functions as a radical scavenger under such conditions. Films of dammar containing 2% Tinuvin 292 and 3% Tinuvin 328 remain intact when aged in a xenon arc fadeometer under exclusion of UV light for as long as 3700 hours, while they normally break down in a few hundred hours. After such a period of accelerated aging the original components of the resin are all still intact and the films remain removable with cyclohexane. No yellowing occurs during heat aging after a preceding period of prolonged fadeometer aging. Changes in the films ...

Major enhancement of the affinity of an enzyme for a transition-state analog by a single hydroxyl group.

The compound 1,6-dihydropurine ribonucleoside, prepared by reduction of nebularine in the presence of ultraviolet light, is bound by adenosine deaminase approximately 10(8)-fold less tightly than 6-hydroxy-1,6-dihydropurine ribonucleoside, a nearly ideal transition-state analog. This difference in affinities, which is associated with the presence of a single hydroxyl group in the second compound, suggests the degree to which one or a few hydrogen bonds may stabilize the transition state in an enzyme reaction of this type.

Light-dependent effects of alpha-terthienyl in eggs, larvae, and pupae of mosquitoAedes aegypti

Alpha-terthienyl is toxic toAedes aegypti larvae in the dark, but its activity is much enhanced in the presence of ultraviolet light. The development of first-instar larvae treated with alpha-terthienyl and ultraviolet light was followed until the emergence of adults. The LC50 value for first instars was about 0.002 ppm. Practically all the larvae which survived 24 hr reached adulthood. Fourth-instar larvae were also sensitive to photochemical treatment. When their development into adults was followed, the LC50 value was 0.45 ppm. Contrary to earlier reports, alpha-terthienyl was also phototoxic in pupae, but not when the adults were about to emerge. The LC50 value was ca. 0.06 ppm for pupae which were 1 or 2 days old. This is the first example where the activity of a photoinsecticide has been demonstrated in pupae. Alpha-terthienyl did not affect the hatching of eggs.

Light-dependent cytotoxicity of fluoranthene: Oxygen-dependent membrane damage

Fluoranthene, in the presence of ultraviolet light (300–400 nm) induces the hemolysis of human erythrocytes. The absence of photohemolysis under anaerobic conditions proves that a photodynamic process is responsible for the light-dependent cytotoxicity.

The toxicity of pyrene in the fish [formula omitted][formula omitted]: Synergism by piperonyl butoxide and by ultraviolet light

A saturated solution of pyrene in water was not toxic to the fish Pimepnales promelas , even in the presence of ultraviolet light. A survival curve possessing one minimum, and therefore defining two LC 50 values, was obtained when fish placed in water containing increasing amounts of a pyrene solution in dimethylsulfoxide were exposed to ultraviolet light after a short incubation period. The phototoxicity was linked to the presence of undissolved pyrene. A normal survival curve with only one LC 50 value was found when pyrene was solubilized with the surfactant Tween-20. Practically no phototoxicity was produced when the pyrene mixtures were filtered before use, or when a saturated aqueous solution of pyrene was used. Piperonyl butoxide, present at a concentration where it was not toxic, synergized the toxicity of pyrene in the dark . The environmental significance of this observation may be considerable.

A Highly Sensitive Method for Quantitative Determination of Abscisic Acid

An abscisic acid derivative was formed by reaction with pentafluorobenzyl bromide which allowed highly sensitive detection by gas-liquid chromatography with electron capture detection. In comparison to the methyl ester derivative, the pentafluorobenzyl derivative of abscisic acid was four times more sensitive to electron capture detection and was stable at room temperature in the presence of ultraviolet light. Derivatization was rapid and the molecular weight of the new compound was confirmed by gas-liquid chromatography-mass spectrometry.

The toxicity of benzo[a]pyrene and pyrene in the mosquito [formula omitted], in the dark and in the presence of ultraviolet light

The phototoxicity of benzo[a]pyrene constitutes a much greater risk to immature forms of the mosquito Aedes aegypti than its mutagenicity or carcinogenicity. First instar larvae, fourth instar larvae, and pupae of the mosquito Aedes aegypti were treated with benzo[a]pyrene at concentrations up to 6.7 ppm, either in the dark or in the presence of long wavelength ultraviolet light (for only 30 min). The irradiations had a profound effect on the fate of first instar larvae. Their LC 50 value for 24 h survival was about 0.002 ppm. When the adult emergence was determined, the LC 50 value was about 0.0015 ppm. The development of fourth instar larvae was also modified by the photochemical treatments, with an LC 50 value for adult emergence of 0.12 ppm. The treatment of pupae had no effect on adult emergence. The LC 50 values for the highly carcinogenic BAP are very similar to those determined for pyrene, its non-carcinogenic parent molecule. This provides one additional proof that the carcinogenicity and the phototoxicity of polycyclic aromatic hydrocarbons are not necessarily related.