Abstract: The compound 5-bromouracil (BrU) may be incorporated into DNA in place of its analog thymine. This review is concerned with the photochemical lesions produced by the action of ultraviolet light on such BrU-DNA, and consequent biological effects of such lesions.

Abstract: In the simple eucaryote Saccharomyces cerevisiae there are at least three phenotypically distinct classes of mutants sensitive to inactivation by radiations and alkylating agents: class I mutants are sensitive to ultraviolet light and nitrogen mustard (HN2); class II mutants are sensitive to X-rays and methylmethane sulphonate (MMS); and class III mutants are sensitive to all four of these agents. We have constructed doubly mutant strains of types (I, I), (I, II), (I, III), and (II, III) and have measured their sensitivity to UV, X-rays, HN2 and MMS in order to characterize the interactions of the various mutant gene pairs. Class (I, III) double mutants proved to be supersensitive to UV and HN2 and class (II, III) double mutants proved to be supersensitive to X-rays and MMS. All other double mutants showed little or no enhancement of sensitivity over their most sensitive single mutant parents. Mutants of class I are known to be defective in excision repair and our results are consistent with the idea that there exist at least two additional pathways for dark repair in yeast, one capable of repairing X-ray and MMS damage to DNA, and another, possibly analogous to post-replication repair in bacteria, that competes with the other two for damaged regions in DNA.

Abstract: The anti-tumor drug cis-platinum(II)diamminodichloride (PDD) induced extensive filamentation in wild-type Escherichia coli and in mutants lacking certain deoxyribonucleic acid (DNA) repair functions (uvrA, recB, recC, and polA); viability of repair-deficient mutants treated with PDD was significantly less than that of wild-type cells. PDD was highly toxic to lex1, lex1 uvrA6 (where its effect was cummulative), and recA13 mutants, all of which were killed without formation of filaments. (3)H-thymine incorporated into DNA of cells subsequently treated with PDD became trichloroacetic acid-soluble at rates similar to those observed after exposure to comparable doses of ultraviolet light (UV) or mitomycin C. PDD, like UV, induced extensive degradation of DNA in recA organisms. After a 30-min lag, PDD inhibited significantly the synthesis of DNA but not of ribonucleic acid or protein in E. coli. However, the relative differences between rates of DNA synthesis observed in PDD-treated and control cells decreased substantially when the duration of pulses ((3)H-thymine) was prolonged from 2 to 5 min. These observations suggest that PDD-induced damage to DNA is reversible, possibly by defined mechanisms of excision and recombination repair.

Abstract: Psoralens have been used previously in an attempt to repigment vitiliginous skin. Recent reports indicate psoralens, activated by long wavelength ultraviolet light (black light), inhibit DNA synthesis in various cell types. This suggested to us a possible new therapeutic use for psoralens in proliferative epidermal diseases such as psoriasis. This study shows that trioxsalen plus black light markedly inhibits epidermal DNA synthesis. Trioxsalen or black light alone has no significant effect. Our own preliminary clinical studies show improvement of chronic plaque type psoriatic lesions in eight of 11 patients using topically applied trioxsalen and black light. We suggest that further critical clinical investigation of psoralens either topically or systemically in combination with black light for proliferative skin diseases is warranted.

Abstract: We have studied chromosomal aberration production in V-79 Chinese hamster tissue culture cells by UV light administered during the post-DNA-synthetic G2 phase of the cell cycle. The treatment produced achromatic lesions and some chromatid deletions in the first post-irradiation mitosis, but no isochromatid deletions or chromatid exchange aberrations. In contrast, when G2 UV-irradiated cells were examined in their second post-irradiation mitosis, there were significant yields of chromatid-type aberrations of all types, including isochromatid deletions and chromatid exchanges. We have earlier reported21 that UV-irradiation during the pre-DNA-synthetic G1 phase of the cell cycle induces only chromatid aberrations and also that most chromosomal aberration production by UV in G1 can be photoreactivated in cells possessing the photoreactivating enzyme. We present here a model for chromosomal aberration production by UV. In the model all aberration production is enzymatically mediated, a consequence of the functioning of known molecular repair mechanisms. The important elements in the model are the following: 1. (1) The vertebrate chromosome is mononeme; i.e., contains but a single DNA double helix during the prereplication G1 phase of the cell cycle. 2. (2) The UV-induced DNA lesion leading to the production of most aberrations is the cyclobutane dimer between adjacent pyrimidines in one polynucleotide strand. 3. (3) Single chain breaks appear at metaphase as achromatic lesions. 4. (4) Dimer removal sometimes leaves unrepaired single chain gaps, possibly as a result of incomplete excision repair. 5. (5) The single-stranded DNA opposite a single chain gap can be cleaved by a single-strand DNAase. 6. (6) Gaps are left in newly synthesized DNA polynucleotide chains opposite defective template chains (i.e., opposite dimers and chain breaks). 7. (7) Double-strand breaks present following local DNA replication may “spread” to the other chromatid by a recombinational process between template and new polynucleotide chains, one from each of the homologous double helices. The model predicts the occurrence of isoachromatic lesions and of chromatid deletions paired (isolocus) with achromatic lesions. Though often not reported, both do, in fact, occur. In addition, the model accounts for the phenomenon of sister-chromatid exchange as a manifestation of a recombinational, or post-replication, repair mechanism. Finally, the model offers a simple interpretation of chromosomal aberration production by a variety of chemical agents.

Abstract: The proximal femoral epiphysis from the right hip of twenty-five mongrel puppies was surgically devascularized on two occasions separated by a four-week interval. Before death the bone was labeled with substances fluorescing in ultraviolet light and the animals were then killed at varying intervals

Abstract: A new restorative material that is polymerized by ultraviolet light is used with a fissure sealant to restore fractured anterior teeth. Tooth structure is not removed in this technique; the fracture site is only cleaned.. After application of a medicament on teeth with near or overt pulp exposures, the fissure sealant is applied and extended to the fractured enamel edge. Enamel surfaces are acid-conditioned and another layer of the sealant is applied. For teeth with near or overt pulp exposures, the placement of the restorative material can be delayed. When the material is placed, it is featheredged to the border of the fissure sealant to provide a leakproof margin. Because the restorative material is shaped before it is polymerized, lengthy finishing procedures are not necessary.

Abstract: The mutations in a series of leucine auxotrophs isolated after treatment with nitrosoguanidine, ultraviolet light, and ICR-191 have been mapped between ilvC and pheA on the Bacillus subtilis chromosome. A fine structure map of the region was constructed by transformation. Analysis of several strains by assaying levels of their leucine bioysnthetic enzymes has shown that the region encodes three enzymes. The order of the genes with respect to the biosynthetic steps catalyzed by the gene products is 1-3-2.

Abstract: ✓ Alterations in spinal cord blood flow patterns in experimental traumatic paraplegia were studied by using thioflavine S, a fluorescent dye that stains the endothelium of blood vessels. Feline spinal cords, exposed by laminectomy, were traumatized with a 400 gm-cm contusion, and a rapid intravenous injection of thioflavine S administered. The spinal cords were excised within one circulation time after the injection, and the resulting spinal cord sections were examined under ultraviolet light. As thioflavine S is a fluorescent substance that binds to the blood vessel walls and as the spinal cord was excised within one circulation time, it was possible to determine in which vessels blood was flowing at the time of injection. Control animals showed blood flow in all parts of the spinal cord. At 15 min postcontusion there was a marked decrease in the number of vessels perfused in the white matter; however, at 30 min many of the vessels had evidence of renewed blood flow. By 1 hr postcontusion the entire gray...

Abstract: A solvent free method is provided for effecting the complete removal of photoresist from a substrate at temperatures up to about 260* C, utilizing in combination with a mixture of oxygen and ozone, an ultraviolet radiation discharge lamp capable of generating at least 100 milliwatts per square centimeter of ultraviolet light on the substrate surface.

Abstract: Laboratory observations were made of the formation of Aitken nuclei and large particles in systems of air containing trace quantities of H2O, S02, NH3 and O3, in varying proportions and under varying conditions of radiation with ultraviolet light. These studies yielded information concerning the photooxidation of SO2, the mechanism of formation of stratospheric aerosols, and the possible role of trace organic gases in atmospheric nucleation processes. Specific results were: The quantum yield for the homogeneous oxidation of SO2, with irradiation in the first excited band is less than 1.0×10−9. The addition compounds of NH3 and SO2, if they form, are not precursors to the formation of ammonium sulfate in the atmosphere. Aitken nuclei are formed by oxidation of SO2, by O atoms with traces of water vapor present. The addition of NH3 to the system of SO2 with O atoms gives very rapid production of high concentrations of Aitken nuclei and large particles, probably of ammonium sulfate. Irradiation of a...

Abstract: A prepolymer containing unsaturated hydrocarbon groups is prepared and mixed on a roller mill with one or more acrylic ester monomers and various additives to make a coating formulation of a desired viscosity. In general, low viscosity formulations are used for overprint varnishes, on paper or foil, or, with pigments, for certain types of printing inks. Higher viscosity formulations are used to apply thick films on panels, tiles or other bodies. Thin films are cured to hardness by brief exposure to ultraviolet light. Thicker films require more energetic radiation such as plasma arc and electron beam radiation. The prepolymers particularly useful for making such radiation curable coatings are the reaction products of polyether polyols and bis- or polyisocyanates and hydroxy alkenes or acrylic (or methacrylic) hydroxy esters, and, likewise, reactive polyamides modified with dicarboxy alkenes, their anhydrides or esters. A small amount of wax incorporated in the coating formulations results in coatings with release characteristics similar to those of PTFE coatings.

Abstract: WE present here a study of the fluorescence and phosphorescence of human eye lenses in vitro with regard to the mechanisms of formation of cataracts. Light transmission by the cornea decreases rapidly with decreasing wavelength, and is essentially zero for wavelengths less than 293 nm1–3. The important effect of this corneal absorption was demonstrated by Bachem3 who induced cataracts in guinea-pigs and rabbits with ultraviolet light and presented an action spectrum to show that the efficiency of in vivo cataract production rose steeply, from zero at 293 nm to maximum at 300 nm, and then fell off sharply at 313 nm with a long tail extending to about 365 nm. This action spectrum and the corneal absorption spectrum are shown in Fig. 1.

Abstract: A composition curable upon exposure to ultraviolet light is disclosed which consists essentially of a vinyl-containing siloxane and siloxane-containing, silicon-bonded hydrogen atoms A mercaptofunctional silicone can be employed in the composition as a cure accelerator Another composition curable upon exposure to ultraviolet light which is disclosed consists essentially of a mercaptofunctional siloxane and a vinyl-containing siloxane

Abstract: POLLARD, E. C., AND RANDALL, E. P. Studies on the Inducible Inhibitor of RadiationInduced DNA Degradation of Escherichia coli. Radiat. Res. 55, 265-279 (1973). The presence of an inducible inhibitor of postirradiation DNA degradation has been shown in several strains of E. coli. The time course of induction has been followed by adding rifampin at various times after induction by ultraviolet light. The dose dependence of induction has been observed for both uv and ionizing radiation and parallels that for the induction of phage X. Using rifampin, the presence of some concomitant DNA synthesis in a cell which is degrading DNA has been shown. The experiments suggest that DNA synthesized after irradiation is not degraded. The induction of the inhibitor is an all-or-nothing process, and a culture of cells which has been induced and then irradiated shows no degradation in most cells and full degradation in the remainder. Cells with the inducible inhibitor show a variation in the survival of colonyforming ability in rich versus lean medium; cells lacking the inhibitor do not show the effect. It is suggested that this is related to the rescue of one or more genomes by the action of the inhibitor.

Abstract: Mutations affecting the production of aflatoxin might be useful in studying its biosynthesis, and in understanding the wide variation in aflatoxigenicity of fungal strains isolated from nature. Two methods of isolating mutants of Aspergillus in which aflatoxin production is attenuated or lost are presented. In one method mutants are selected on the basis of altered fluorescence under ultraviolet light. The second method utilizes a mutant strain which produces aflatoxin and an orange-red mycelial pigment not detected in the wild type. Unpigmented mutants derived from this strain exhibit lowered or lost aflatoxigenicity.

Abstract: A body-carried medical history card has a visible indicia bearing portion with identification data and critical medical data and has a medical record microfilm bearing portion with one or more strips of laterally connected microfilm frames of a selfproofed medical history. Visible indicia and microfilm frames are integrally formed as images in a thick piece of film which is carried on the person of the subject of the medical data. The card is made by reducing identified and certified medical history pages and producing a strip of microfilm frames of those pages. A jacket having an opaque area is printed with visible indicia such as the identification of the person and critical medical data taken from the medical history pages. The microfilm is fitted in a sleeve within the jacket and a heavy diazo film is exposed through the jacket using ultraviolet light. The heavy film is then developed with visible indicia and microfilm images produced within the film spaced from edges and surfaces. A backing is added, and the visible indicia are read against the backing. A magnetic tape is added for storing machine readable information. In a dog tag size card, the microfilm frames are arranged in a substantially square area in the tag-card, and a hole for receiving a body member encircling chain penetrates the visible indicia bearing portion.

Abstract: The vinyl asbestos and asphalt floor tiles are formed with a predetermined image printed on the surface thereof by rotogravure, planograph, letterpress or other printing techniques. Unlimited design possibilities not heretofore feasible by conventional valley printing of the continuous sheet of tile composition prior to cutting into individual tiles, are thus presented, the sheet being printed either during or after the sheet calendering operation. The continuous sheet, traveling at a rate of about 80-200 ft./min. is surfaced following said printing with a clear, durable wear layer having, upon curing, an advantageous combination of enhanced properties including enhanced resistance to scratching and abrasion, together desirably with improved resistance to staining, scorching and other desirable properties. The dimensional stability characteristics of the surfaced tiles are comparable to those of the untreated base tile, minimizing the problem of curling during storage, application and use. The clear wear layer is a cross-linked polymeric product of a fluid photo-polymerizable coating applied to the continuous sheet at a temperature of at least about 140 DEG F and cured by exposure to ultraviolet light of sufficient intensity to initiate curing in less than about 15 seconds, typically with exposure times of from a fraction of a second to about 10 seconds. The thus-printed treated sheet is thereafter cut while warm to form individual tiles surfaced with said clear, durable, dimensionally stable wear layer having an advantageous combination of improved wear characteristics.

Abstract: Skin disorders are controlled by irradiation with a mixture of a major portion of ultraviolet light of wave length in the 2537A area with almost to about as much infrared light, and a very small amount of visible light, derived from a filament-controlled 4-watt spheroidal-form mercury vapor lamp for a predetermined period of time. A preferred apparatus for the use of such lamps includes a plurality of lamps, including a central lamp, surrounded by a bank of similar lamps forming a square configuration. The lamps are disposed in a cylindrical casing in front of a reflective mirror disposed in the casing. The casing is provided with a detachable cover member comprising an annular outer ring forming a central opening therein with an inner annular ring detachably connected to the perimeter of the central opening which inner ring is provided with a small central opening disposed in front of the central lamp in the casing so that the lamp can be used individually or collectively, to cover any desired area from that covered by a single lamp to that covered by the entire bank of lamps, with radiant energy of equal intensity over the area to be covered.

Abstract: For practical purposes avian RNA tumour viruses have been divided into sarcoma and leukosis viruses. Sarcoma viruses have the ability to transform chick embryo fibroblasts in vitro and to induce fibro-sarcomas in vivo after a latent period of about 7 to 21 days. Leukosis viruses do not transform chick embryo fibroblasts, although they replicate in them, and in vivo most wild strains induce principally lymphoid leukosis after a latent period of over 90 days. They also frequently induce erythroid leukosis (erythroblastosis) and osteopetrosis, and occasionally other tumours. Non-transforming mutants of sarcoma viruses, which have all the in vitro properties of leukosis viruses, have been produced experimentally by exposure to ultraviolet light (Toyoshima, Friis & Vogt, 1970), by γ-irradiation (Golde, 1970) and by treatment with chemicals (Graf et al. 1971). These results suggest that leukosis viruses may originate from sarcoma viruses, perhaps by loss of genetic material either by mutation or by segregation of subgenomic components (Toyoshima et al. 1970; Graf et al. 1971; Martin & Duesberg, 1972).

Abstract: — Ultraviolet (UV) light-induced incorporation of bromodeoxyuridine (BrdUrd) into parental DNA of an excision-defective mutant of Escherichia coli has been observed by selective photolysis of bromouracil (BrUra)-containing regions in the parental DNA. It appears that the BrUra-containing regions occur only in that DNA which has served as a template for normal semiconservative replication. After an exposure at 254 nm which results in one pyrimidine dimer per 45times 106 daltons, incubation in BrdUrd resulted in BrUra–containing regions ˜ 1.5 times 104 nucleotides in length at intervals of ˜ 55 times 106 daltons in the parental DNA. Thus approximately one BrUra-containing region has occurred for every 1.2 pyrimidine dimers in the parental DNA. The observed incorporation of BrdUrd is interpreted in terms of a proposed model for postreplication repair in which genetic exchanges produce single-strand gaps in the parental DNA.

Abstract: Timed catches of Laspcyrcsia pomonella (L.) were made in sex-pheromone traps over two seasons at San Jose and over one season at Placerville, Calif., where timed catches were made also in ultraviolet light traps. The mating-flight response appeared to be circadian and entrained to the daily photoperiod. Where not limited by other factors, this daily response began about three hours before sunset and extended to about two hours after sunset. High temperatures (above approximately 80°F) as well as low (below ca. 55°F) changed this pattern by limiting the response, and thus the observed periodicity varied considerably with time of season and with location. Temperature thresholds for the light trap were approximately the same as for the Pheromone trap. Low temperatures were more limiting in the early season on the light trap than on the pheromone trap, because the low-temperature threshold was often attained after some catches were made in the pheromone traps but before daylight intensity was sufficiently low for attraction by light traps. Later in the season, high temperatures often limited the duration of the daily mating flight, but they seldom limited duration of catch in the light traps. Clearly, catches in either type trap did not consistently reflect actual population abundance.

Abstract: Osseous coagulum is regarded by some clinicians as a useful material for grafting in procedures aimed at bone replacement. Its value in this regard has been assessed experimentally. Holes ∼ 2 mm in diameter were made in the right and left parietal bones of 15 middle-aged Wistar-strain albino rats weighing ∼ 500 g. Osseous coagulum was obtained from the interparietal bone, and was placed into the left hole, while the right served as a control. Three of the animals were injected with tetracycline; these animals were sacrificed at 4, 8 and 12 weeks postoperatively, and undemineralized sections of their calvaria were viewed in ultraviolet light to assess accretion of new bone. The remaining 12 animals were sacrificed at postoperative intervals of 1, 2, 3, 4, 8 and 12 weeks, and serial sections of their calvaria were examined by routine histological methods. The observations indicate that, in this system in which repair is normally poor, osseous coagulum consistently did not appear to have induced the formation of new bony callus. These findings bring into question the value of using osseous coagulum as an autograft in clinical periodontal procedures aimed at restoring the attachment apparatus.