Showing papers on "Ultraviolet light published in 1980"

Survey of Radiosensitivity in a Variety of Human Cell Strains

Abstract: gamma-Ray sensitivity for cell killing was assayed in 54 human cell strains, including some derived from individuals suffering from certain heritable diseases The overall range of Do values in this study was 38 to 180 rads, indicating a considerable range of variability in humans The normal sensitivity was described by a range of Do values of 97 to 180 rads All ten ataxia telangiectasia cell strains tested proved radiosensitive and gave a mean Do value of 57 +/- 15 (SE) rads, and these represent the most radiosensitive human skin fibroblasts currently available Representative cell strains from familial retinoblastoma, Fanconi's anemia, and Hutchinson-Gilford progeria occupied positions of intermediate sensitivity, as did one of two ataxia telangiectasia heterozygotes Six xeroderma pigmentosum cell strains together with two Cockayne's syndrome cell strains (all known to be sensitive to ultraviolet light) fell into the normal range, indicating an absence of cross-sensitivity between ultraviolet light and gamma-irradiation

Methotrexate induced liver cirrhosis. Studies including serial liver biopsies during continued treatment.

Abstract: SUMMARY Seven hundred and sixty-four liver biopsies were performed in 328 psoriatics on treatment with methotrexate or being considered for systemic treatment either with methotrexate or with psoralens and long-wave ultraviolet light. The diagnosis of cirrhosis was established histologically in twenty-one patients. Two patients had cirrhosis in their premethotrexate biopsy and were not given methotrexate. The remainder all showed no signs of cirrhosis or fibrosis in their premethotrexate biopsy. The difference between the methotrexate treated psoriatics and the premethotrexate group was highly significant. Among thirty-nine patients treated for more than 5 years, ten developed cirrhosis (25.6%). Almost all patients were on a divided dose intermittent oral dosage schedule. The cumulative dose of methotrexate, when cirrhosis was first found, ranged from 590 to 8105 mg, with an average dosage of 2200 mg. Other factors contributing to cirrhosis in this study seem to be previous treatment with arsenic, a previous intake of alcohol, and lowered renal function. Data on later serial biopsies from fourteen patients, of which eleven continued to receive methotrexate due to very severe psoriasis, seem to indicate that methotrexate induced liver cirrhosis is not of a very aggressive nature. When evaluated blind no progression was found in most of the later biopsies, and a ‘cumulative cirrhosis index’ composed of the combined gradings for fibrosis, assessment of membrana limitans, fibrous destruction and regeneration showed a tendency to decrease. In three patients the latest of the serial biopsies showed no cirrhosis. The observation period on continued methotrexate therapy ranged from 1 to 7 years. None of the patients with cirrhosis differed from the remaining patients on methotrexate in their laboratory results for evaluating liver damage, and apart from transient increases in serum glutamic pyruvic transaminases no abnormalities were found. The data support the necessity of liver biopsies in the control of psoriatics treated with methotrexate. Liver biopsies should be performed at least in all psoriatics in whom a cumulative dosage of methotrexate exceeds 1.5g. The data also indicate that methotrexate can be continued at least for a while in patients where the indication is strong enough, if the dosage is maintained as low as possible and alcohol consumption avoided.

Rapid membrane filtration-epifluorescent microscopy technique for direct enumeration of bacteria in raw milk.

Abstract: Membrane filtration and epifluorescent microscopy were used for the direct enumeration of bacteria in raw milk. Somatic cells were lysed by treatment with trypsin and Triton X-100 so that 2 ml of milk containing up to 5 x 10 somatic cells/ml could be filtered. The majority of the bacteria (ca. 80%) remained intact and were concentrated on the membrane. After being stained with acridine organe, the bacteria fluoresced under ultraviolet light and could easily be counted. The clump count of orange fluorescing cells on the membrane correlated well (r = 0.91) with the corresponding plate count for farm, tanker, and silo milks. Differences between counts obtained by different operators and between the membrane clump count and plate count were not significant. The technique is rapid, taking less than 25 min, inexpensive, costing less than 50 cents per sample, and is suitable for milks containing 5 x 10 to 5 x 10 bacteria per ml.

Effects of inhibitors of DNA synthesis on spontaneous and ultraviolet light-induced sister-chromatid exchanges in Chinese hamster cells.

Abstract: Effects of inhibitors of DNA synthesis on spontaneous and ultraviolet light (UV)-induced sister-chromatid exchanges (SCE) were examined in a Chinese hamster cell line, V79 B-1. The inhibitors used were hydroxyurea (HU), 1-beta-D-arabinofuranosylcytosine (ara-C), aphidicolin (APC), 2',3'-dideoxythymidine triphosphate (ddTTP), neocarzinostatin (NCS), novobiocin (NB) and cycloheximide (CHX). HU, ara-C, and APC increased spontaneous SCE frequency, and had a synergistic effect on UV-induced SCE frequency. DdTTP, NCS and NB failed to show any statistically significant effect on either spontaneous or UV-induced SCE frequencies, though NCS and NB did slightly increase both spontaneous and UV-induced SCE frequencies. On the contrary, CHX decreased spontaneous SCE frequency, and more drastically, also UV-induced SCE frequency. These results are interpreted with respect to the replicating fork of DNA, a structure postulated to be involved in the formation of spontaneous and UV-induced SCE. A new model for SCE formation is proposed.

Human tumor cell strains defective in the repair of alkylation damage.

Abstract: We have previously identified four human astrocytoma cell strains as defective in the repair of N-methyl-N' -nitro-N-nitrosoguanidine (MNNG) damaged adenovirus 5. We now show that two of these strains (the only two tested), in comparison to other tumor strains or normal human skin fibroblasts, are very sensitive to MNNG-produced killing as measured by colony forming ability, but are normally sensitive to ultraviolet light. Further, such repair deficient cells may be cultured from tumors of the colon, lung, skin, and neck. The phenotype of deficient repair of MNNG-treated adenovirus 5 has now been found in a subgroup of 9 of the 39 human tumor strains tested. We propose to call this phenotype the Mer(-) phenotype. None of the 22 strains of normal human skin fibroblasts tested showed deficient repair of MNNG damage. MNNG treatment (80 microM) causes a decrease in semi-conservative DNA synthesis from which Mer(-) tumor cells do not recover, but from which cells capable of normal repair of MNNG damage (Mer(+)) do. Somewhat paradoxically, Mer(-) cells show more MNNG-stimulated DNA synthesis ('repair synthesis') than do Mer(+) cells. Besides being deficient in the repair of MNNG-damaged adenoviruses Mer(-) cells also have difficulty in repairing viruses damaged either by other N-alkyl-N'-nitro-N-nitrosoguanidines, or by N-methyl- or N-ethyl-N-nitrosoureas.

Abrasion resistant ultraviolet light curable hard coating compositions

Abstract: A radiation curable coating composition comprising (A) colloidal silica (B) acryloxy or glycidoxy functional silanes (C) non-silyl acrylates and (D) catalylic amounts of UV light sensitive cationic and radical type photoinitiators is provided, which cures to a transparent hard coating exhibiting improved abrasion resistance.

Tetracycline-labeled human bone from ancient Sudanese Nubia (A.D. 350)

Abstract: Nubian bone recovered from an X-group cemetery (A.D. 350 to 550) exhibits a pattern of fluorescence identical to that of modern tetracycline-labeled bone. When it is viewed under ultraviolet light at 490 angstroms, fluorophors are visible as a characteristic yellow-green fluorescence on surfaces that were actively mineralizing at the time of exposure. Contamination of stored grains provided the proper environment for cultivation of tetracycline-producing Streptomycetes. Evidence for exposure to antibiotics in an archeological population is relevant to studies of the evolution of R factors and to the interpretation of health and disease within the population.

Cell variants showing differential susceptibility to ultraviolet light--induced transformation.

Abstract: Six variant clones isolated from a subclone of BALB/3T3-A31 clone were classified into three groups according to their different susceptibilities to cell transformation by ultraviolet light irradiation: highly susceptible, intermediately susceptible, and resistant. All variant clones showed similar susceptibility to cytotoxic effects induced by ultraviolet light.

Large-scale isolation of UV-sensitive clones of CHO cells.

Abstract: We have isolated 54 ultraviolet light (UV) sensitive clones of Chinese hamster ovary (CHO) cells, including two from a parent cell line which is hypersensitive to ethyl methanesulfonate (EMS) and is also sensitive to X rays. A replica plating technique was used for the isolation of two of the clones, and a semiautomated technique was used for the isolation of the other 52 clones. We have observed UV sensitization of up to 5-fold in the mutants relative to the parent in terms of the slopes of the survival curves. Seven of the clones were examined for DNA repair competence using a repair replication assay, and all exhibited a DNA repair defect resembling that seen in human mutant xeroderma pigmentosum cells. We have also demonstrated an approximately 9-fold enhancement in the UV mutagenic response of two of the repair replication-defective clones relative to the parent for resistance to ouabain, 6-thioguanine, and 8-azaadenine.

Habitat use and response to patches of prey by desert insectivorous bats

Abstract: I examined the habitat use patterns of an Arizona insectivorous bat community using ultrasonic sensing equipment which allowed field identification of bat species based on their echolocation calls. Response to prey patchiness by the species encountered was tested using ultraviolet lights to attract swarms of insects. No partitioning of habitat or time was observed, there being a high degree of species overlap, and many species of bats appeared to be positively associated. All species responded to light-induced prey patches on at least some occasions. Analysis of prey populations indicated that food, though abundant, was extremely patchy in distribution, both spatially and temporally. These data indicate a bat community in which species are highly adapted to an abundant, but patchy food source.

Cross-linking of mRNA to Proteins by Irradiation of Intact Cells with Ultraviolet Light

Abstract: Ehrlich ascites tumor cells were irradiated with ultraviolet light to cross-link intracellular RNAs to their tightly bound proteins. The efficiency of such cross-linking in vivo was measured by two independent methods, namely by phenol/chloroform extraction and by isopycnic centrifugation. After short irradiation times more than 70% of the ribosomal RNAs and more than 80% of the mRNA were found to be cross-linked to protein. The size of the cross-linked RNAs was essentially unchanged, indicating that the irradiation does not lead to extensive fragmentation of the RNA. Covalent poly(A)-containing mRNA-protein complexes were isolated by oligo(dT)-cellulose chromatography in the presence of sodium dodecylsulphate. The complexed proteins were freed from RNA by extensive nuclease degradation and analysed by polyacrylamide gel electrophoresis. The results show that some specific proteins are associated with poly(A)-containing RNA in vivo.

Identification, Purification, and Partial Characterization of an Organic Anion Binding Protein from Rat Liver Cell Plasma Membrane

Abstract: Uptake of bilirubin, sulfobromophthalein (BSP), and other organic anions by the liver is a process with kinetics consistent with carrier mediation. The molecular basis of this transport mechanism is unknown. In the search for the putative organic anion carrier or receptor, the interaction of BSP with rat liver cell plasma membrane (LPM) has been studied. Specific binding of [(35)S]BSP to LPM was determined using a filtration assay. Results revealed high affinity (K(a) = 0.27 muM(-1)), saturable (6.3 nmol/mg protein) binding, which was eliminated after preincubation with trypsin. Although [(35)S]BSP was strongly bound to LPM, the binding was rapidly reversible, preventing direct identification and study of a specific binding site(s). To avoid this problem, a photoaffinity probe was devised, in which [(35)S]BSP is covalently bound to LPM after exposure to ultraviolet light. Subsequent sodium dodecyl sulfate gel electrophoresis and fluorography revealed radioactivity predominantly associated with a single 55,000-mol wt protein. A protein with identical electrophoretic mobility was purified from deoxycholate solubilized LPM after affinity chromatography on glutathione-BSP-agarose gel. This protein migrated as a single band on sodium dodecyl sulfate gel electrophoresis and on urea gel isoelectric focusing. It contained 1-2 residues of sialic acid per 55,000-dalton protein, and was immunologically distinct from rat albumin and ligandin. It bound bilirubin with a K(d) of 20 muM, as determined by tryptophan fluorescence quenching. Although the high affinity of this LPM protein for organic anions suggests that it may function as a hepatocellular organic anion receptor, its role in transport of these compounds is unknown.

Identification of genetic elements associated with muscle structure in the nematode Caenorhabditis elegans.

Abstract: A search for new mutants with altered body-wall muscle cell structure has been undertaken in the nematode C elegans. One-hundred seventeen mutants were isolated after mutagenesis with ethyl methanesulfonate or ultraviolet light, enrichment by a motility-requiring test, and screening by polarized light microscopy; 102 of these mutants were in ten previously established genes, whereas 15 mutants permitted the identification of seven new complementation groups in C elegans. Two of the new genes map on linkage group I (unc-94 and unc-95) and four genes are sex linked (unc-96, unc-97, unc-98, and unc-99). One complementation group (unc-100) could not be mapped because of the special characteristics of its cohort mutants. Representative mutants of the mapped genes were examined by polarized light and electron microscopy. All of the mutants exhibit disruptions of the normal A and I band organization of thick and thin filaments. Several of the mutants produce collections of thin filament-like structures. In one of these cases, HE177 demonstrated collections of somewhat wider, intermediate-sized filaments as well, and the HE195 mutant produces paracrystalline aggregates of thin filaments amidst looser arrangements of similar structures. The mutants in newly identified genes, as well as the new mutants in previously established genetic loci, have promise as tools in the study of myofibrillar assembly and function. Among the 22 complementation groups associated with body-wall structure in C elegans, it is likely that some genes code for regulatory and morphogenetic functions in addition to the well-studied structural, contractile, and calcium-associated proteins in muscle.

The effects of three pso genes on induced mutagenesis: a novel class of mutationally defective yeast

Abstract: Reverse and forward mutation, induced by photoaddition of 8-methoxypsoralen (8-MOP) and 3-carbethoxypsoralen (3-CPs) or ultraviolet light (UV), are reduced in three pso mutants of Saccharomyces cerevisiae. The pso1–1 strain exhibits a lower frequency of spontaneous reversion (antimutator) and is almost entirely unaffected by the three agents in both the haploid and diploid states. The pso2–1 strain demonstrates very reduced frequencies of 8-MOP and 3-CPs plus 365 nm radiation-induced mutations in happloid and diploid cells. UV-induced mutations are slightly reduced, whereas survival is almost normal. The pso3–1 strain is mutable by 8-MOP and 3-CPs photoaddition only in the low-dose range. After UV treatment, survival of pso3–1 is nearly normal, whereas the frequencies of induced mutants are diminished as compared to the normal PSO+. An analogue of adenine, 6-N-hydroxyaminopurine, is capable of inducing reversions in wild type, as well as in pso and rad6–1 mutant strains, indicating that this drug may act as a direct mutagen in yeast. The comparison of photoaddition of the bifunctional agent (8-MOP) to that of the monofunctional one (3-CPs) confirms that cross-links, as well as monoadditions, are mutagenic in S. cerevisiae. Repair, of the recombinational type, taking place in diploid cells or in haploid cells in G2 phase leads to higher survival, but appears to be error-free.

Cross-Linking of Proteins to Nucleic Acids by Ultraviolet Light

Abstract: Early in the 1960s Smith (1962) and Alexander and Moroson (1962) independently published experimental results indicating that absorption of ultraviolet light could induce cross-linking of protein to DNA in living cells. Since these initial observations there has been increasing experimental interest in photoinduced cross-linking of proteins to nucleic acids. Photobiologists are intrigued by the possibility that nucleic acid-protein cross-linking is an important mode of ultraviolet light induced damage in biological systems. Molecular biologists and biochemists interested in structural relations in nucleic-acid-protein systems (e.g., chromatin, ribosomes) are examining the feasibility of using UV-cross-linking as a means of determining contact points between nucleic acid and protein in these complexes. Photochemists are exploring the structures and mechanisms of formation of adducts of nucleic acid bases and related compounds with amino acids and amino acid analogs; these studies may have direct relevance to the goal of understanding the chemical basis of UV-induced cross-linking in nucleic acid-protein complexes.

Cell-mediated immunity against herpes simplex induction of cytotoxic T lymphocytes.

Abstract: The conditions required for the induction of both primary cytotoxic T lymphocytes (CTL) in vivo and secondary CTL in vitro against herpes simplex virus type 1 (HSV-1)-infected cells were defined. Primary CTL responses occurred only in mice exposed to infectious HSV-1. These responses, which were shown to be mediated by T lymphocytes, peaked at 1 week and had disappeared by 2 weeks after infection. The level of primary cytotoxicity was enhanced by treatment of mice with cyclophosphamide before infection. Secondary in vitro CTL responses were more pronounced and were induced by some forms of inactivated virus as well as by infectious HSV-1. Thus, both ultraviolet light- and glutaraldehyde-inactivated preparations of HSV-1 induced CTL, but heat-inactivated and detergent-extracted antigens failed to do so. The reasons for the differing efficiency of infectious and noninfectious HSV-1 for induction of CTL are discussed.

Ultraviolet curable silicone adhesives

Abstract: An ultraviolet light curable silicone pressure sensitive adhesive is provided which is comprised of an epoxy functional silicone polymer and a combination of standard MQ silicone resins or epoxy functional MQ silicone resins, which can be cured to an adhesive composition in the presence of certain bis(aryl)halonium salt catalysts.

Behavior of pathogenic bacteria in the oyster, Crassostrea commercialis, during depuration, re-laying, and storage.

Abstract: Oysters (Crassostrea commercials) harvested from major cultivation areas within the state of New South Wales, Australia, were commonly contaminated with low levels of the food-poisoning organisms Bacillus cereus, Clostridium perfringens, and Vibrio parahaemolyticus. Salmonella was found in oysters on only one occasion. These bacteria were cleansed from oysters during oyster purification by re-laying in a non-polluted waterway. Oysters were laboratory contaminated to levels in excess 1,000 cells per g with either B. cereus, C. perfringens, V. parahaemolyticus, Salmonella typhimurium, or S. senftenberg. These species were cleansed from such oysters during purification in a laboratory depuration unit that used ultraviolet light for sterilizing the depuration water. Escherichia coli was also cleansed from oysters under the same re-laying or depuration conditions so that its measurement alone could be used to indicate the cleansing of the above pathogenic species. The levels of these bacteria were also measured during the storage of oysters under conditions that occur during marketing. While B. cereus counts remained relatively stable during storage, the Salmonella spp. gradually decreased in numbers and C. perfringens rapidly died off. V. parahaemolyticus counts increased slightly during the first 4 days of storage, after which decreases occurred.

Keratoses and nonmelanoma skin tumors in long-term photochemotherapy (PUVA)

Abstract: Four hundred eighteen patients were treated with oral photochemotherapy up to 5 years and monitored regularly for the occurrence of precancerous conditions or tumors of the skin. Out of this group, six patients (1.4%) developed actinic keratoses and five (1.2%), epidermal tumors (three squamous cell carcinomas, one basal cell carcinoma, one keratoacanthoma) 12 to 53 months after initiation . of 8-methoxypsoralen-photochemotherapy (PUVA). Ten of these eleven patients belonged to a group of 172 individuals with a history of previous exposure to arsenic, ionizing radiation, and/or methotrexate who were considered a risk group. All of the four carcinoma patients had previously had one or more courses of arsenic therapy. No tumors were observed in the remaining 246 nonrisk patients. The mean age of the keratosis-tumor group (59 ± 9 years) and the total cumulative long-wave ultraviolet light (UVA) dose (1,045 ± 959 J/cm 2 ) were significantly higher (p 2 ) of the 407 patients without such skin changes. The skin type and the time period between initiation of PUVA therapy and the final evaluation of the patients did not exhibit substantial differences in both groups. The observed incidence of epidermal carcinomas in the risk group (2.3%) was considerably higher than the expected age-sex-specific incidence of a randomized population (0.1%), whereas the incidence in the nonrisk group (0%) corresponded to the expected rate. However, data on the tumor incidence in psoriatics not treated with PUVA and matched for previous treatments and risk factors were not available. This study shows that the incidence of nonmelanoma skin tumors in long-term PUVA patients without previous medication of arsenic or treatment with ionizing radiation does not differ from the expected incidence of the general population. However, there is an increased incidence of tumors in PUVA patients if certain risk factors are present. The risk factor in our series is previous medication with arsenic, which is carcinogenic per se.

Radiation cured coating and process therefor

Abstract: An article having an opaque, pigmented, radiation cured coating is formed by: (a) applying to a substrate a thin layer of pigmented radiation curable material and partially curing same with ionizing irradiation or ultraviolet light in an oxygen containing atmosphere; and (b) then applying a second layer of unpigmented radiation curable material over the partially cured first layer and completely curing both the first and second layers with ionizing irradiation or ultraviolet light in an inert atmosphere.

Ultraviolet light absorbing agents and compositions and articles containing same

Abstract: There are provided ultraviolet light absorbing agents of the following general formula ##STR1## wherein: X is ##STR2## Y is H or OH, Z is H, OH, OQ or OW, where at least one Z is OH if Y is H; Q is --CH 2 (CH 2 ) n Si(R 2 ) x (OR 1 ) y ; and W is --C m H 2m+1 ; where x=0, 1 or 2, y=1, 2 or 3, x+y=3, R 1 =alkyl or alkanoyl having 1 to 6 carbon atoms, R 2 =alkyl having 1 to 6 carbon atoms, n=0, 1 or 2, and m=1 to 18. Also provided are organopolysiloxane protective coating compositions containing said ultraviolet light absorbing agents having unique utility for protecting transparent plastic articles.

Quantitation of 1-β-d-Arabinofuranosylcytosine 5′-Triphosphate in the Leukemic Cells from Bone Marrow and Peripheral Blood of Patients Receiving 1-β-d-Arabinofuranosylcytosine Therapy

Abstract: A method for the detection and quantitation of 1-β-d-arabinofuranosylcytosine 5′-triphosphate (ara-CTP), the active metabolite of 1-β-d-arabinofuranosylcytosine (ara-C), in the bone marrow cells and leukemic cells of the peripheral blood from patients receiving ara-C therapy is described. ara-CTP is separated from normal cellular nucleotides by high-pressure liquid chromatography and is quantitated by its absorbance of ultraviolet light at 280 nm with a lower limit of sensitivity of 25 pmol/2 × 10 7 cell equivalents. During separate courses of continuous infusion of different therapeutic doses of ara-C, ara-CTP accumulated in the leukemic bone marrow cells of a patient with acute myelogenous leukemia in proportion to the dose of ara-C. Continuous infusion of ara-C (90 mg/sq m/day) resulted in plateau levels of ara-CTP in peripheral blast cells after 24 hr (115 pmol/1 × 10 7 cell equivalents). A priming dose of ara-C (125 to 250 mg/sq m) followed by a 1-hr infusion of an equal dose of ara-C to patients with acute myelogenous leukemia facilitated the determination of ara-CTP retention in bone marrow and peripheral blood leukemic cells in vivo . This procedure should be useful for extended studies of the biochemical pharmacology of ara-CTP in vivo .

Hydralazine-pyrimidine interactions may explain hydralazine-induced lupus erythematosus

Abstract: Hydralazine, the prototypic drug that induces systemic lupus erythematosus, reacts with thymidine and deoxycytidine. Analysis of a reaction mixture of therapeutic concentrations of hydralazine with labeled thymidine reveals at least four labeled products. At higher concentrations, hydralazine reacts with labeled deoxycytidine to form at least three labeled products. Formation of these products is markedly enhanced by exposure to ultraviolet light. The reaction of hydralazine with thymidine and deoxycytidine may be in part responsible for initiating drug-induced systemic lupus erythematosus.

Ultraviolet Light-induced Transformation of Human Cells to Anchorage-independent Growth

Abstract: We have developed a system for ultraviolet light (UV) transformation of human embryonic cells to anchorage-independent growth. The procedure involves multiple UV irradiations, post irradiation growth, and plating in soft agar. Transformants are obtained at frequencies from 1 to 80 per 105 cells at UV exposures to 25 J/sq m. The resulting transformants can be subcultured on solid surfaces. The cells show crisscrossing and piling up; they reach 2- to 5-fold higher saturation densities than the parental cells. Some subcultures show increased plating efficiency in soft agar and increased life span. The susceptibility of the UV transformation process to apparent photoenzymatic reversal implies that pyrimidine dimers play a role in its induction.