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  • 1
    Electronic Resource
    Electronic Resource
    Inactivation of Candida albicans by ultraviolet radiation (1969)
    Springer
    Archives of microbiology 64 (1969), S. 289-314 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Inactivation of Candida albicans by ultraviolet (uv) light is markedly dependent upon (a) the cell division stage and (b) the nutrition and growth temperatures of cells both before and after irradiation. Cells grown at 37°C after irradiation show lower survivals than those grown at 25°C. At either recovery temperature, cells which had been cultured before irradiation at 37°C are able to sustain less uv damage prior to inactivation than those cultured at 25°C. The radiosensitivities of budding and non-budding cells are the same when survivals are scored at 25°C; at low uv dosages, cells show slightly poorer recoveries on enriched medium than on minimal medium whereas at higher dosages, their recoveries on both kinds of media are equivalent. In contrast, at 37°C, uv treated non-budding cells are much more susceptible to inactivation than budding cells; non-budding cells also express much poorer recovery on enriched medium than on minimal medium at 37°C whereas budding cells survive equally well on either medium. Though non-budding cells grown for irradiation on minimal or enriched media exhibit the same radiosensitivites, budding cells grown for irradiation on enriched medium are more susceptible to inactivation at 37°C than those grown on minimal medium. The particularly poor recovery by irradiated non-budding cells at 37°C is correlated with their unique tendency to undergo a transitory filamentation when initiating growth at that temperature. Evidence is presented that neither the filamentous growth per se nor the temporary inhibition of cell division associated with filamentation causes the poor recovery. Furthermore, while irradiated non-budding cells at 37°C exhibit singular susceptibility to inhibition of recovery by metabolic antagonists which disturb protein synthesis, the course of their filamentous growth is not affected by such agents. It is concluded that recovery from irradiation and the instigation of cytokinesis by non-budding cells of C. albicans result from different metabolic processes which may be related through a common temperature sensitive step. C. albicans does not photoreactivate and observations on recovery by cells prevented from undergoing immediate postirradiation replication do not indicate the existence of a system for dark repair of DNA damage comparable to that occurring in bacteria. Difficulties attending a valid demonstration of DNA dark repair in yeasts are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00417011
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro cytotoxicity of chrysotile asbestos to human pulmonary alveolar macrophages is decreased by organosilane coating and surfactant (1986)
    Springer
    Cell biology and toxicology 2 (1986), S. 293-309 
    Details
    ISSN: 1573-6822
    Keywords: chrysotile asbestos ; dipalmitoyl lecithin ; organosilane ; pulmonary alveolar macrophage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Human pulmonary alveolar macrophages were used to quantitate the cytotoxic effect of surface-altered chrysotile asbestos. Little difference was observed in mortality between chrysotile asbestos that was surface-treated to a 42% extent by a hydrophobic organosilane or untreated chrysotile. Little or no effect on mortality was observed when human pulmonary alveolar macrophages were cultured with untreated chrysotile or acid-leached asbestos in the presence of 10 mM dipalmitoyl lecithin. However, when human pulmonary alveolar macrophages were cultured with a hydrophobically-treated (to a 42% or 95% extent) chrysotile asbestos in the presence of 10 mM dipalmitoyl lecithin, a statistically significant decrease in mortality was observed compared to untreated chrysotile. No mutagenic activity was observed when V79 cells were cultured with acid-leached, or 42% hydrophobically-treated chrysotile asbestos, even when human pulmonary alveolar macrophages were included as an activation source. The 95% hydrophobically-treated and acid-leached chrysotile also exhibited decreased binding of benzo[a]pyrene compared to untreated chrysotile asbestos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122697
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  • 3
    Electronic Resource
    Electronic Resource
    The sesquiterpene lactone hymenoxon acts as a bifunctional alkylating agent (1987)
    Springer
    Cell biology and toxicology 3 (1987), S. 39-49 
    Details
    ISSN: 1573-6822
    Keywords: bitterweed ; DNA adduct ; DNA cross-linking ; hymenoxon ; sesquiterpene lactone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Hymenoxon, a toxic sesquiterpene lactone found in bitterweed, bound deoxyguanosine in a cell free system and formed adducts with guanine residues in cellular DNA. The reactive dialdehyde form of hymenoxon formed stable Schiff base products with deoxyguanosine which were separable from unreacted hymenoxon and deoxynucleosides by reverse phase high pressure liquid chromatography. Hymenoxon adducts which eluted as a single impure peak from the octadecylsilane column separated on amino and diphenyl-bonded phases with 10% methanol. Tritiated nucleoside adducts were isolated and purified from CFW mouse sarcoma cells treated with hymenoxon. Proton nuclear magnetic resonance spectra of purified hymenoxon-deoxyguanosine adducts revealed a loss of signals for hydroxyl groups in the bishemiacetal of hymenoxon. 13C-nuclear magnetic resonance spectra revealed that the major adduct has 35 carbon atoms, indicating an interaction of at least two guanine residues per hymenoxon molecule and suggesting that hymenoxon may cross-link DNA. Sedimentation analysis of treated DNA further showed that DNA cross-linking by hymenoxon (30 µg/ml) was equivalent to that of a known cross-linking agent, mitomycin C (7.5 µg/ml). Hymenoxon was more cytotoxic to DNA cross-link repair-deficient Chinese hamster ovary cell mutants than to repair proficient strains. These data combine to indicate that hymenoxon acts as a bifunctional alkylating agent which cross-links DNA in mammalian cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117824
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of age and dietary restriction on daily sperm production and number and transit time of epididymal spermatozoa in the mouse (1992)
    Springer
    Age 15 (1992), S. 65-71 
    Details
    ISSN: 1574-4647
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Dietary restriction extends the DNA repair capacity and life span of mice. Age-related changes in spermatogenesis and transit time of epididymal spermatozoa were evaluated to determine if dietary restriction altered the age-related changes in these traits as well. At weaning, mice were fed NIH-31 diet ad libitum or restricted to 60% of the ad libitum and sacrificed at 6, 12, 19, 22, or 26 months of age. The number of maturation phase spermatids or epididymal spermatozoa were counted by phase contrast cytometry of testicular or epididymal homogenates. Daily sperm production/testis (DSP/T) was determined by dividing the number of spermatids per testis by the 4.84 day life span of these spermatids. Daily sperm production per g parenchyma (DSP/G) was calculated by dividing DSP/T by the testicular parenchymal weight. Transit time of epididymal spermatozoa was calculated by dividing the number of epididymal spermatozoa by the DSP/T of the attached testis. Over both treatments, testicular and parenchymal weights were significantly decreased with age. While both DSP/G and DSP/T were similar (P〉0.05) for 19, 22, and 26 months of age, they were lower (P〈0.05) at 6 and 12 months of age, and there was a trend for them to be lower at 26 months of age. Age also reduced the number and the transit time of epididymal spermatozoa. DSP/G was not uniform in adult mice. Over all ages, dietary restriction had no significant effect on testicular weight or DSP/G, but it significantly reduced body and epididymal weight, number of epididymal spermatozoa, and epididymal spermatozoan transit time. Transit time of spermatozoa in the mouse epididymis was very long in younger adult mice, could vary widely, and was reduced by age and dietary restriction. Although not statistically significant, there was a trend for a delay in obtaining maximum DSP/T at 12 months and a delay in obtaining the age-related, reduced DSP/T at 26 months in the dietary restricted group compared to that seen in the ad libitum group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02435004
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