Showing papers on "Ultraviolet light published in 1987"

MAP 1C is a microtubule-activated ATPase which translocates microtubules in vitro and has dynein-like properties.

Abstract: We observe that one of the high molecular mass microtubule-associated proteins (MAPs) from brain exhibits nucleotide-dependent binding to microtubules. We identify the protein as MAP IC, which was previously described in this laboratory as a minor component of standard microtubule preparations (Bloom, G.S., T. Schoenfeld, and R.B. Vallee, 1984, J. Cell Biol., 98:320-330). We find that MAP 1C is enriched in microtubules prepared in the absence of nucleotide. Kinesin is also found in these preparations, but can be specifically extracted with GTP. A fraction highly enriched in MAP 1C can be prepared by subsequent extraction of the microtubules with ATP. Two activities cofractionate with MAP 1C upon further purification, a microtubule-activated ATPase activity and a microtubule-translocating activity. These activities indicate a role for the protein in cytoplasmic motility. MAP 1C coelectrophoreses with the beta heavy chain of Chlamydomonas flagellar dynein, and has a sedimentation coefficient of 20S. Exposure to ultraviolet light in the presence of vanadate and ATP results in the production of two large fragments of MAP 1C. These characteristics suggest that MAP 1C may be a cytoplasmic analogue of axonemal dynein.

Potential involvement of free radical reactions in ultraviolet light‐mediated cutaneous damage*

Abstract: Free radicals are chemical species characterized by an odd number of orbital electrons or by pairs of electrons of similar directional spin isolated singly in separate orbitals. Consequently most of these agents are highly reactive and usually exhibit an extremely short half-life, although due to steric and resonance effects some exceptions occur. Some radicals and their precursors, such as the diradical O2 which exists in the triplet state, represent a critical and essential element of normal metabolism of aerobic organisms where, under normal circumstances, controlled reduction of reactive oxygen species occurs via the cytochrome oxidase or cytochrome P-450 mixed function monooxygenase systems. In addition to reactive oxygen species, organisms may be subjected to a wide-range of other free radicals or their precursors, including those of both exogenous and endogenous origin. Elaborate defense mechanisms have evolved to avoid cellular damage from these highly reactive species. Enzymes, such as the superoxide dismutase, the glutathione peroxidase/reductase system, and catalase; interactions with conjugated diene systems such as those found in melanins, carotenoids, and tocopherols; and direct reduction by sulphydryl compounds, phenols, and purines represent but a few of these natural defense systems. Despite a strong rationale for considering free radicals as pathologic agents, progress in implicating these agents, or their reactions, in pathologic processes has been arduous. The fore-most hurdle to providing definitive evidence for free radical involvement rests with the highly transient nature of these species, hardly reaching measurable levels in vivo and thereby making rigorous testing of the hypothesis extremely difficult. Indeed, free radical damage has been studied, for the most part, by indirect means–usually by measurement of known free radical reaction intermediates and products from which free radical involvement is implied. Nevertheless, free radical formation has been shown to occur in UV-irradiated skin and a considerable body of circumstantial evidence has been amassed that strongly infers that these agents, or reactions initiated by them, are responsible for at least some of the deleterious effects of UV upon skin.

A new mechanism for induced vitamin D deficiency in calcium deprivation.

Abstract: Synthesis of vitamin D in the skin in response to ultraviolet light is the main determinant of vitamin D status in man and it is therefore surprising that rickets and osteomalacia, clinical signs of vitamin D deficiency, remain common in tropical and subtropical countries. Skin pigmentation can reduce vitamin D formation but this is a negligible limitation in people exposed to abundant ultraviolet light. Earlier studies in animals and man suggested that another environmental factor, the low calcium/high cereal diet typical of susceptible populations, might affect the efficiency of vitamin D utilization. We show here in rats that the rate of inactivation of vitamin D in the liver is increased by calcium deprivation. The effect is mediated by 1,25-dihydroxyvitamin D, produced in response to secondary hyperparathyroidism, which promotes hepatic conversion of vitamin D to polar inactivation products that are excreted in bile. This finding has widespread implications both for understanding the pathogenesis of endemic rickets and in that it provides a unifying mechanism for the development of vitamin D deficiency in many clinical disorders.

Reactive nitrogen in the troposphere.

Abstract: The atmospheric chemistry and transport of nitrogen oxides and peroxyacetyl nitrate are explained. Although most of the emissions of reactive nitrogen occur as nitric oxide, it is typically converted to nitrogen dioxide in minutes by reaction with ozone. Nitrogen dioxide in turn absorbs ultraviolet light at relatively long wavelengths and photolyzes rapidly, eventually reforming ozone. In recent years, the role of PAN as a carrier and reservoir of nitrogen oxides has received considerable attention. This possibility arose from the understanding that PAN exists in equilibrium with nitrogen dioxide.

Energy yields for hydrogen cyanide and formaldehyde syntheses: the HCN and amino acid concentrations in the primitive ocean.

Abstract: Prebiotic electric discharge and ultraviolet light experiments are usually reported in terms of carbon yields and involve a large input of energy to maximize yields. Experiments using lower energy inputs are more realistic prebiotic models and give energy yields which can be used to estimate the relative importance of the different energy sources on the primitive earth.

Isolation and cross-sensitivity of X-ray-sensitive mutants of V79-4 hamster cells

Abstract: The V79-4 Chinese hamster line was mutagenized and surviving clones screened for X-ray sensitivity using a replica microwell technique. One slightly sensitive clone and 3 clearly sensitive clones were isolated from approximately 5000 screened, and designated irs 1 to irs 4. The 3 more sensitive clones showed different responses to the genotoxic agents mitomycin C (MMC), ethyl methanesulphonate (EMS) and ultraviolet light (UV). irs 1 showed considerable sensitivity to all the agents tested, in the order MMC much greater than EMS greater than UV. irs 2 and irs 3 had similar sensitivities to EMS and to UV (EMS greater than UV) but irs 3 was more sensitive than irs 2 to MMC. None of these mutants is identical in phenotype to previously published mutants.

Credit card and method of making the same

Abstract: An improved credit card having a clear, unbroken metallized surface with printed graphics thereon which is scratch resistant and a method of making the same are disclosed. The method involves heat transferring a metallized foil to a first surface of a plastic substrate, silk-screen printing over the metallized foil with ultraviolet curable ink, drying the ink with ultraviolet light and overlaminating the printed foil with a clear polyester film coated with a heat-activated adhesive or coating it with an ultraviolet curable varnish which is cured by applying ultraviolet light to the coating. The plastic substrate is in the form of a large sheet from which a plurality of cards are die cut after the printing and application of the transparent film. A magnetic tape is then applied to the back of each card.

Ablation and etching of polymethylmethacrylate by very short (160 fs) ultraviolet (308 nm) laser pulses

Abstract: The effect of pulse width on the ablation of polymers has been extended to ultrashort pulses (160 fs) of 308 nm wavelength. Polymethylmethacrylate has negligible absorption at this wavelength for one‐photon excitation. With the ultrashort pulse clean etching without any sign of thermal damage can be achieved at fluences as little as 0.2–0.3 J/cm2. This is the first demonstration that the high power of ultrashort pulses of ultraviolet light can produce photochemical etching by taking advantage of multiphoton excitation to dissociative states.

Enhanced antigen-presenting capacity of cultured Langerhans' cells is associated with markedly increased expression of Ia antigen.

Abstract: Recent studies indicate that when epidermal Langerhans' cells (LC) are cultured for 2 to 3 days they, in comparison to freshly prepared LC, exhibit markedly enhanced ability to stimulate T cell proliferative responses in oxidative mitogenesis and in the mixed epidermal-leukocyte reaction. In this study, we determined whether cultured LC enhance antigen-specific T cell responses, and whether such enhanced stimulatory capacity correlates with the level of Ia antigen expressed on LC. We used C3H/He (Iak) epidermal cells as stimulators and, as responder cells, both the trinitrophenyl-specific clones D8 and SE4, which were assayed for [3H]dThd incorporation, and the pigeon cytochrome c specific hybridoma 2C2, which was assayed for interleukin 2 production. Cultured LC induced 10 to 100 times greater proliferation or interleukin 2 production by responder cells than did freshly prepared LC. The intensity of I-Ak and I-Ek, expressed on cultured LC as assessed by immunofluorescence and flow cytometry, was found to be 10 to 36 times greater on a per cell basis than that on freshly prepared LC. Depletion of LC from fresh epidermal cell suspensions by anti-Iak and complement or treatment with 50 mJ/cm2 medium range ultraviolet light or cycloheximide before culture abrogated both the increase in Ia expression and antigen-specific clonal proliferation. The results suggest that when LC are removed from their usual epidermal milieu, they express increased amounts of Ia and become more potent stimulators of T cell responses.

Reactivation of latent herpes simplex virus infection by ultraviolet light: A human model

Abstract: Infection with herpes simplex virus often results in a latent infection of local sensory ganglia and a disease characterized by periodic viral reactivation and mucocutaneous lesions. The factors that trigger reactivation in humans are still poorly defined. In our study, five patients with documented histories of recurrent herpes simplex virus infection on the buttocks or sacrum were exposed to three times their minimal erythema dose of ultraviolet light. Site-specific cutaneous herpes simplex virus infection occurred at 4.4 ± 0.4 days after exposure to ultraviolet light in 8 of 13 attempts at reactivation. We conclude that ultraviolet light can reactivate herpes simplex virus under experimentally defined conditions. This model in humans should prove useful in evaluating the pathophysiology and prevention of viral reactivation.

Method and apparatus for surface treating of substrates

Abstract: A method for surface treating of thin substrates such as semiconductor wafers, wherein a semiconductor wafer formed with deep and minute trenches on its surface is horizontally placed on a spinner in a chamber with its trenched surface directed up, and then ultraviolet light is emitted to the surface of the wafer to dissolve impurities sticking in the trenches, and thereafter etchant is spouted from a nozzle to the trenched surface of the wafer being spinned about a vertical axis at a high speed, and next the inside of the chamber is rendered at a lower pressure than atmospheric pressure and the atmospheric pressure is recovered after the lapse of a predetermined time, and thus a series of these steps of etchant supplying, pressure reducing, and pressure recovering are carried out until the complete entrance of the etchant into the interior surfaces of the trenches is effected, so as to even or smooth the interior surfaces, and finally the wafer is treated with rinsing, and heating and drying.

Fluid purification system.

Abstract: A fluid purification system includes an elongated ultraviolet radiation emitting tube and independent fluid flow-controlling conduits. Each conduit is transparent to allow ultraviolet light emitted by the tube to enter the conduit, and defines a continuous path, and is helically wound closely about the tube to insure that fluid flow through the conduits is exposed to the ultraviolet light. One embodiment of the system includes a filter typically a carbon filter, having inlet and outlet ports. An end of each conduit is connected to one of the inlet and outlet ports of the filter. The system thus exposes the fluid to ultraviolet radiation both before and after the fluid is filtered. Other embodiments include reverse osmosis units and deionization units wherein each entry, exit or discharge port is isolated from contamination by having a coiled connecting tube for the fluid exposed to ultraviolet radiation.

Calcein as a Fluorescent Marker of Otoliths of Larval and Juvenile Fish

Abstract: Calcein is a fluorescent compound that can bind with alkaline earth metals, such as calcium. Upon binding, an increase in fluorescence under ultraviolet light results. Therefore, calcein was evaluated as potentially useful for creating a fluorescent mark in the otoliths of larval and juvenile fish. Such a mark was produced in the sagittae of larvae and juveniles of three species of estuarine fishes after a 2-h immersion in a solution of 125 mg/L in seawater. The mark was easily distinguished under ultraviolet epifluorescent microscopy. This technique provides an alternative to the use of tetracycline in age and growth studies.

Photofootprinting in vivo detects transcription-dependent changes in yeast TATA boxes

Abstract: To elucidate critical steps in the transcription initiation process, we have devised a protocol for obtaining information about DNA structure and DNA–protein interactions at nucleotide level resolution from intact yeast cells. Our procedure combines the ultraviolet light 'footprinting' method developed by Becker and Wang1 with the 'genomic sequencing' technique described by Church and Gilbert2. Using this approach we were able to detect the binding of GAL 4 protein at sites within the upstream activating sequence (UASG) previously mapped using other in vivo and in vitro foot-printing procedures3–5. We also observed transcription-dependent changes in sensitivity of DNA to ultraviolet-induced covalent modification at several positions between the upstream activating sequence and the transcription initiation sites of the GAL 1 and GAL 10 genes. The most prominent of these changes occurs at a common site within the putative 'TATA' boxes of the two genes. Ultraviolet modification at this site is enhanced only in transcrip-tionally active promoters.

Process of coating an ophthalmic lens

Abstract: An abrasion-resistant coated plastic lens element and a method for coating the element with an abrasion-resistant coating includes forming a coating on a face of a mold that is substantially cured and adherable to lens-forming material. The coating composition consists of reactants, approximately 70% to 95% of which have at least triacrylate functionality and approximately 5% to 30% of which have diacrylate functionality, a photoinitiator, a polymerization inhibitor reactive with oxygen, and a silane adhesion promoter and an acid to activate the silane adhesion promoter. The coating is applied to the face of the mold to form a substantially uniform coating and is then subjected to ultraviolet light in an ambient oxygen-containing environment such that a hard abrasion-resistant coating is formed on the mold. The mold is then filled with a lens-forming composition which is reactive with acrylate groups of the coating at a coating/lens interface. The lens-forming composition is permitted to cure in the mold to form a lens having a hard abrasion-resistant coating. No further post curing treatment is required since the lens leaves the mold at its maximum cure, hardness, and abrasion resistance.

Process for preparing silicone microparticles

Abstract: Microparticles, such as microspheres and microcapsules, comprising a solid organopolysiloxane are prepared by irradiating a dispersion of discrete entities with ultraviolet light. The discrete entities are dispersed in a UV-transparent fluid continuous phase and are sphere-like particles of a UV-curable, liquid organopolysiloxane composition, or such a liquid organopolysiloxane composition containing a material to be encapsulated. The microparticles may be elastomeric or resinous and are useful as filler particles and time-release capsules.

Recovery from ultraviolet light-induced inhibition of DNA synthesis requires umuDC gene products in recA718 mutant strains but not in recA+ strains of Escherichia coli

Abstract: Ultraviolet light (UV) inhibits DNA replication in Eschericia coli and induces the SOS response, a set of survival-enhancing phenotypes due to derepression of DNA damage-inducible genes, including recA and umuDC. Recovery of DNA synthesis after UV irradiation ("induced replisome reactivation," or IRR) is an SOS function requiring RecA protein and postirradiation synthesis of additional protein(s), but this recovery does not require UmuDC protein [Khidhir, M. A., Casaregola, S. & Holland, I. B. (1985) Mol. Gen. Genet. 199, 133-140]. IRR occurs in strains carrying either recA718 (which does not reduce recombination, SOS inducibility, or UV mutagenesis) or umuC36 (which eliminates UV mutability), but not in recA718 umuC36 double mutants. In recA430 mutant strains, IRR does not occur whether or not functional UmuDC protein is present. IRR occurs in lexA-(Ind-) (SOS noninducible) strains if they carry an operator-constitutive recA allele and are allowed to synthesize proteins after irradiation. We conclude the following: (i) that UmuDC protein corrects or complements a defect in the ability of RecA718 protein (but not of RecA430 protein) to promote IRR and (ii) that in lexA(Ind-) mutant strains, IRR requires amplification of RecA+ protein (but not of any other LexA-repressed protein) plus post-UV synthesis of at least one other protein not controlled by LexA protein. We discuss the results in relation to the essential, but unidentified, roles of RecA and UmuDC proteins in UV mutagenesis.

Furanocoumarins in wild parsnip : effects of photosynthetically active radiation, ultraviolet light, and nutrients

Abstract: Previous studies of wild parsnip, Pastinaca sativa L, revealed a significant degree of genetically controlled variation in furanocoumarin production In this study, the influence of environmental factors, namely, soil nutrients, photosynthetically active radia- tion, and ultraviolet (UV) radiation, on the production of furanocoumarins in the wild parsnip was examined experimentally Aboveground tissues of plants grown under all combinations of three light intensities and three nutrient levels (N, P, K) were analyzed for the absolute and relative amounts of furanocoumarins In a second experiment the effect of ultraviolet radiation on furanocou? marin production was evaluated by growing plants under full sunlight with and without an ultraviolet screen Light and nutrient availability jointly affected the concentration of four of the six furanocoumarins present (sphondin and angelicin being the exceptions) Both nutrients and light were limiting factors in furanocoumarin production insofar as low availability of either resource limited the effect of variation in the other resource Relative amounts of the furanocoumarins were independently influenced by light and nutrient availability UV radiation increased the concentration of all but two of the furanocoumarins (imperatorin and sphondin) and also influenced the relative amounts of furanocoumarins Since fur? anocoumarins are UV-phototoxic to many organisms, including insects, the response of parsnip plants to UV radiation may affect their resistance to herbivores

Photoaffinity labeling of peripheral-type benzodiazepine-binding sites.

Abstract: The use of a novel photoaffinity label for the peripheral-type benzodiazepine-binding site is described. This compound, PK 14105, has high affinity (4 nM) and selectivity for cardiac benzodiazepine-binding sites. Under ultraviolet light, PK 14105 couples covalently to an 18,000-Da membrane protein which apparently corresponds to the (or a part of the) cardiac benzodiazepine-binding site. Since covalent attachment of PK 14105 totally precludes the binding of other ligands to this binding site, it is suggested that, during ultraviolet irradiation, this compound inserts covalently into the binding domain of the peripheral-type benzodiazepine-binding site.

Evidence of near‐ultraviolet emission during electrical‐tree initiation in polyethylene

Abstract: The spectra of light emitted during electrical‐tree initiation in low‐density polyethylene used in high‐voltage cables were investigated. Light in the visible and in the near‐ultraviolet range was detected. Low‐density polyethylene subjected to highly divergent fields at voltages below the light‐inception level did not develop an electrical tree, and it is suggested that the light‐inception voltage is the threshold for insulation degradation. The ultraviolet light emitted at voltages above the light‐inception level could cause degradation of the polymer. A model is proposed to explain the mechanism of electroluminescence. Ultraviolet stabilizers added to the polymer prolonged the time to electrical‐tree initiation by preventing photodegradation of the polymer.

Microbial and photolytic dissipation of imazaquin in soil.

Abstract: Microbial degradation of imazaquin {2[4,5dihydro -4-methyl4(1-methylethyl)5oxolH-imidazol-2 yl] -3 -quinolinecarboxylic acid} was monitored by measuring 14C02 evolution for 7 months under controlled laboratory conditions. Up to 10% of the 14C chainlabeled imazaquin that was applied to a Crowley silt loam was evolved as 14C02 in 7 months. Less evolution of 14Co2 occurred on a Sharkey silty clay, a soil with higher clay and organic matter content, than on silt loam soils. The loss of 66 to 100% of the imazaquin applied to a Crowley silt loam incubated for 8 months at 18 C or 3 5 C, respectively, suggested that metabolic changes in addition to CO2 evolution were occurring. Rapid loss of imazaquin phytotoxicity occurred when soils were held at warm-moist (35 C and -33 kPa) conditions conducive to microbial growth. Imazaquin was more persistent in soils stored under cool, dry (18 C and -100 kPa) conditions. lmazaquin on a soil surface dissipated rapidly when exposed to ultraviolet light or sunlight. Photodecomposition could be a major mode of imazaquin dissipation if this herbicide is allowed to remain on the soil surface. Additional index words. 14C02 evolution, incubation, ultraviolet light, volatilization, persistence, photodecomposition.

Identification of a receptor protein in cotton fibers for the herbicide 2,6-dichlorobenzonitrile.

Abstract: The herbicide 2,6-dichlorobenzonitrile (DCB) is an effective and apparently specific inhibitor of cellulose synthesis in higher plants. We have synthesized a photoreactive analog of DCB (2,6-dichlorophenylazide [DCPA]) for use as an affinity-labeling probe to identify the DCB receptor in plants. This analog retains herbicide activity and inhibits cellulose synthesis in cotton fibers and tobacco cells in a manner similar to DCB. When cotton fiber extracts are incubated with [3H]DCPA and exposed to ultraviolet light, an 18 kilodalton polypeptide is specifically labeled. About 90% of this polypeptide is found in the 100,000g supernatant, the remainder being membrane-associated. Gel filtration and nondenaturing polyacrylamide gel electrophoresis of this polypeptide indicate that it is an acidic protein which has a similar size in its native or denatured state. The amount of 18 kilodalton polypeptide detectable by [3H]DCPA-labeling increases substantially at the onset of secondary wall cellulose synthesis in the fibers. A similar polypeptide, but of lower molecular weight (12,000), has been detected upon labeling of extracts from tomato or from the cellulosic alga Chara corallina. The specificity of labeling of the 18 kilodalton cotton fiber polypeptide, coupled with its pattern of developmental regulation, implicate a role for this protein in cellulose biosynthesis. Being, at most, only loosely associated with membranes, it is unlikely to be the catalytic polypeptide of the cellulose synthase, and we suggest instead that the DCB receptor may function as a regulatory protein for β-glucan synthesis in plants.

Alzheimer's disease cells exhibit defective repair of alkylating agent—induced DNA damage

Abstract: The most common cause of senile and presenile dementia is Alzheimer's disease, a disorder with an undetermined cause. A number of studies have indicated that neurons from patients with Alzheimer's disease have decreased ribonucleic acid levels and reduced protein synthesis. Recent studies using lymphoblasts from patients with Alzheimer's disease have indicated that these cells are more sensitive to deoxyribonucleic acid (DNA)–alkylating agents. We have used cell survival, unscheduled DNA synthesis, and alkaline elution to assess the capacity for DNA repair in skin fibroblasts from normal control subjects, control subjects with central nervous system disease, and patients with Alzheimer's disease. Our results indicate that the Alzheimer's disease cells, unlike normal cells, fail to repair methyl-methane sulfonate–induced DNA damage. Both normal and Alzheimer's disease cells are able to ameliorate the effects of ultraviolet light. These results indicate that a specific pathway for DNA repair is affected in Alzheimer's disease. The repair defect may be related to the cause of the disease or may be the cause of the disease.

Rapid method for detection of lactose fermenting oral microorganisms.

Abstract: A rapid inexpensive assay for lactose fermentation which can be performed on individual colonies in situ and which does not negate subcultivation is described. The assay is based on the ability of bacterial β-galactosidase to hydrolyze 4-methylumbelliferyl-β-D-galactoside (MUG) and form 4-methylumbelliferone, a compound which is brightly fluorescent under long-wave ultraviolet light. 1% MUG in dimethyl sulfoxide was stable at room temperature for at least 21 days. Maximal MUG fluorescence reactions required viable bacterial cultures. The MUG test represents a convenient means to distinguish the lactose-negative Bacteroides intermedius and Haemophilus actinomycetemcomitans, both suspected major periodontopathogens, from the lactose-positive Bacteroides melaninogenicus group and Haemophilus aphrophilus, organisms of little or no periodontopathic significance. The MUG test may also greatly help in distinguishing lactose from nonlactose fermenting organisms of nonoral origin.