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C W Moore

Publications and source records attributed to C W Moore.

At least 37 records · Page 2Linked to original sources
PubMed1990

Degradation of DNA and structure-activity relationship between bleomycins A2 and B2 in the absence of DNA repair.

The contribution of DNA repair to the net number of DNA breaks produced during chemical degradation of DNA was determined by using temperature-sensitive mutant cells deficient in ATP-dependent DNA ligase [poly(deoxyribonucleotide):poly(deoxyribonucleotide) ligase, EC 6.5.1.1]. In a very sensitive assay for determining lesions introduced into Saccharomyces cerevisiae DNAs, 2-14C- and 6-3H-prelabeled DNAs from ligase-proficient and ligase-deficient cells were sedimented together through precalibrated, isokinetic alkaline sucrose gradients. DNA ligation was slower after chemical degradation of DNA by bleomycin than after gamma irradiation. DNA breaks increased approximately linearly with drug concentrations, and were approximately equivalent for ligase-proficient and ligase-deficient cells. These results were unexpected because ligase-deficient, but not ligase-proficient, cells lacked the capacity to eliminate DNA breaks produced by bleomycin. The results indicated that DNA repair did not occur during the chemical degradation of DNA under the experimental conditions. Bleomycin B2 produced considerably more DNA breaks than bleomycin A2 over a range of concentrations in ligase-proficient cells, which tolerated higher numbers of DNA breaks in general than ligase-deficient cells. The chemical analogues are structurally identical except for their cationic C-terminal amine. The actual number of DNA breaks produced by bleomycin A2 or bleomycin B2, and not the concentration of bleomycin A2 or bleomycin B2 per se, determined the amount of cell killing. DNA repair is critical in quantitating DNA breaks produced by chemicals, but was ruled out as a factor in the higher DNA breakage by bleomycin B2 than bleomycin A2.

Bleomycin↗
PubMed1989

Cleavage of cellular and extracellular Saccharomyces cerevisiae DNA by bleomycin and phleomycin.

Low-molecular-weight phleomycin (Mr approximately 1500-1600) is considerably less active on a per mol basis than structurally related bleomycin in degrading purified Saccharomyces cerevisiae DNA. Phleomycin also exhibits a substantially higher requirement than bleomycin for ferrous ions. However, phleomycin (0.13 to 3.3 x 10(-6) M) produced 7 to 350 times more breaks than bleomycin in prelabeled intracellular [2-14C]DNA and [6-3H]DNA and is considerably more cytotoxic than bleomycin. Phleomycin and bleomycin produced equivalent numbers of DNA breaks at equivalent, physiologically meaningful levels of survival, indicating that DNA breaks are related to lethal properties of the anticancer glycopeptides. Phleomycin degradation of extracellular DNA was only detectable at greater than or equal to 1.7 x 10(-4) M, approximately two orders of magnitude higher than the concentrations of phleomycin which yielded equivalent fragmentation of intracellular DNA, indicating that phleomycin causes substantially more degradation of intracellular DNA than extracellular DNA. In contrast, bleomycin (greater than or equal to 1.7 x 10(-5) M) degradation of purified DNA is quite extensive and considerably greater than the degradation of DNA in cells incubated with the same or higher concentrations of bleomycin. Neither phleomycin nor bleomycin cleaved extracellular DNA in the absence of ferrous ions, although both chemical analogues cleaved intracellular DNA without adding iron. Therefore, the requirement for metal ion in stimulating DNA degradation by the two structural families of glycopeptidic antibiotics is met by the cell itself.

Bleomycin↗
PubMed1989

Growth phase dependency of chromatin cleavage and degradation by bleomycin.

Preferential cleavage of Saccharomyces cerevisiae chromosomes in internucleosomal (linker) regions and nonspecific degradation of chromatin by an anticancer antibiotic which degrades DNA were investigated and found to increase in consecutive stages of growth. Cleavage of DNA in internucleosomal regions and intensities and multiplicities of nucleosomal bands were dependent on drug concentration, growth phase of the cells, and length of incubation. Cellular DNA was least degraded during logarithmic phase. After cells progressed only one generation in logarithmic phase, low concentrations (6.7 x 10(-7) to 3.4 x 10(-6) M) of bleomycin produced approximately three to seven times more DNA breaks. Internucleosomal cleavage was highest, and the most extended oligonucleosomal series and extensive chromatin degradation were observed during stationary phase. It is concluded that the growth phase of cells is critical in determining amounts of the highly preferential cleavage in internucleosomal regions and overall breakage and degradation of DNA. Mononucleosomal bands were most intense, indicating the greatest accumulation of DNA of this size. Mean mononucleosomal lengths were 165.9 +/- 3.9 base pairs, in agreement with yeast mononucleosomal lengths. As high-molecular-weight chromatin was digested by bleomycin, oligonucleosomes and, eventually, mononucleosomes became digested. Therefore, it is also concluded that bleomycin degradation of oligonucleosomes and trimming of DNA linker regions proceed to degradation of the monosomes (core plus linker DNA).

Bleomycin↗
PubMed1988

Internucleosomal cleavage and chromosomal degradation by bleomycin and phleomycin in yeast.

Native chromosomal structure, breakage, and overall degradation were studied following the reaction of whole cells with the anticancer drug bleomycin and structurally related phleomycin. Electrophoretic analyses of cellular DNA established that phleomycin was more reactive with DNA than equimolar bleomycin in the range of 0.67-33 x 10(-6) M, produced an optimally visible, though less-extended, oligonucleosomal series at concentrations 12 to 35 times lower than bleomycin, and degraded DNA within nucleosomes. Chromosomes were cleaved into nucleosomes and degraded by phleomycin over substantially narrower dose ranges (1 to 2 x 10(-6) M) than by bleomycin (about 1 to 17 x 10(-5) M). Bleomycin exhibited higher specificity for internucleosomal cleavage than phleomycin, and trimmed but did not degrade nucleosomes at less than or equal to 3 x 10(-5) M. Identical nucleosomal repeat sizes (166 +/- 3.8 base pairs) were produced by the analogues. The higher reactivity of phleomycin does not result solely from its higher rate of internucleosomal and intranucleosomal chromatin cleavage, since short phleomycin reactions always resulted in more extensive chromatin cleavage than long bleomycin reactions at low concentrations. In vivo (cellular) repair of chromatin damage was comparable (approximately 90% in 1 h) after cells were exposed to low drug concentrations which produced similar numbers of chromatin breaks, and thus also does not account for the higher chromosomal breakage caused by phleomycin than bleomycin at low doses. At high doses, unrepaired breaks are substantially higher after phleomycin treatments than after bleomycin treatments, and thus contribute to the higher lethal effects of phleomycin than bleomycin.

Bleomycin↗
PubMed1988

Accumulation of cis-diamminedichloroplatinum(II) and platinum analogues by platinum-resistant murine leukemia cells in vitro.

Three murine leukemia lines resistant to cis-diamminedichloroplatinum(II) and one line resistant to diaminocyclohexane (DACH) platinum(II) complexes were compared to their platinum-sensitive parent lines to determine whether differences in net platinum accumulation were related to the resistant phenotype. The cis-diamminedichloroplatinum(II)-resistant lines (L1210PtR4, L1210DDP5, P388PtR4) and the DACH-resistant line (L1210DACH) were incubated in vitro with cis-diamminedichloroplatinum(II), [sp-4-2-(1R,2R)]-(1,2-cyclohexanediamine-N-N')dichloroplatinum(II) , [sp-4-2-(1R,2R)]-(1,2-cyclohexanediamine-N-N')[ethanedioato( 2-)- O,O']platinum(II), or diaminocyclobutanedicarboxylatoplatinum(II) and the time-dependent cellular platinum levels determined by flameless atomic absorption spectrophotometry. Cell lines resistant to a given platinum complex showed a reduction in the rate of platinum accumulation when compared to the sensitive line at 37 degrees C. Intracellular levels of diaminocyclobutanedicarboxylatoplatinum(II) were too low to confidently measure under the conditions of this study. Our data suggest that the mechanism of platinum resistance in these cell lines may be related to a reduced accumulation of the platinum-containing drug, although patterns of cross-resistance suggest other mechanisms may be operative as well.

Animals↗
PubMed1988

Elevated DNA polymerase beta activity in a cis-diamminedichloroplatinum(II) resistant P388 murine leukemia cell line.

The activity of DNA polymerase beta, which is an enzyme involved in repair of DNA damage, was assessed in P388 murine leukemia cell lines sensitive and resistant to cis-diamminedichloroplatinum(II) (cis-Pt). The resistant line was selected with cis-Pt and showed cross-resistance to a number of alkylating agents, but not to an anthracycline. The DNA polymerase beta activity was found to be elevated 5-fold in the resistant line based upon activity per mg cell protein and elevated 4-fold based upon activity per 10(7) cells. The characterization of elevated activity of an enzyme active in DNA repair in a cell line resistant to DNA damaging agents describes a possible mechanism of resistance in addition to those previously found.

Animals↗
PubMed1988

Differential mismatch repair can explain the disproportionalities between physical distances and recombination frequencies of cyc1 mutations in yeast.

Recombination rates have been examined in two-point crosses of various defined cyc1 mutations that cause the loss or nonfunction of iso-1-cytochrome c in the yeast Saccharomyces cerevisiae. Recombinants arising by three different means were investigated, including X-ray induced mitotic recombination, spontaneous mitotic recombination, and meiotic recombination. Heteroallelic diploid strains were derived by crossing cyc1 mutants containing a series of alterations at or near the same site to cyc1 mutants containing alterations at various distances. Marked disproportionalities between physical distances and recombination frequencies were observed with certain cyc1 mutations, indicating that certain mismatched bases can significantly affect recombination. The marker effects were more pronounced when the two mutational sites of the heteroalleles were within about 20 base pairs, but separated by at least 4 base pairs. Two alleles, cyc1-163 and cyc1-166, which arose by G.C----C.G transversions at nucleotide positions 3 and 194, respectively, gave rise to especially high rates of recombination. Other mutations having different substitutions at the same nucleotide positions were not associated with abnormally high recombination frequencies. We suggest that these marker effects are due to the lack of repair of either G/G or C/C mismatched base pairs, while the other mismatched base pair of the heteroallele undergoes substantial repair. Furthermore, we suggest that diminished recombination frequencies are due to the concomitant repair of both mismatches within the same DNA tract.

Alleles↗
PubMed1988

Bleomycin-induced DNA repair by Saccharomyces cerevisiae ATP-dependent polydeoxyribonucleotide ligase.

In contrast to ligase-deficient (cdc9) Saccharomyces cerevisiae, which did not rejoin bleomycin-induced DNA breaks, ligase-proficient (CDC9) yeast cells eliminated approximately 90% of DNA breaks within 90 to 120 min after treatment. Experimental conditions restricted enzymatic removal of the unusual 3'-phosphoglycolate termini in DNA cleaved by bleomycin and involved doses producing equivalent numbers of DNA breaks or doses producing equivalent killing.

Bleomycin↗
PubMed1985

Ultrarapid recovery from lethal effects of bleomycin and gamma-radiation in stationary-phase human diploid fibroblasts.

An ultrarapid phase of cellular recovery, as measured in liquid holding type experiments, was studied in stationary-phase human fibroblasts exposed to bleomycin or cobalt-60 gamma-irradiation yielding comparable levels of cell killing. This rapid recovery was both faster and considerably greater in magnitude after bleomycin treatments. Bleomycin survival curves were multiphasic, indicating the presence of treated cells with varying sensitivities either at the beginning of treatments or as a result of resistance which developed during the treatment period. The amount of both ultrarapid (within 2 to 10 min) and slower recovery was dose dependent after irradiation with 200 to 800 rads or 30-min exposures to bleomycin (5 to 100 micrograms/ml). Following bleomycin treatments resulting in surviving fractions of 1 to 2%, survival increased up to 8-fold after only 2 min of posttreatment incubation. This rapid increase in survival was followed by a slower increase over time periods up to 3 h. In contrast, the rates of cellular recovery after gamma-irradiation were more gradual from 0 to 3 h. Recovery at all posttreatment intervals was always greater after bleomycin than after gamma-treatments, following doses yielding 1 to 50% survival. The ultrarapid component of cellular recovery after bleomycin treatments may have implications for both clinical cancer management and cellular studies directed toward determining mechanisms of action of bleomycin.

Bleomycin↗
PubMed1985

Rapid and slow DNA rejoining in nondividing human diploid fibroblasts treated with bleomycin and ionizing radiation.

The rejoining of DNA single-strand breaks produced after bleomycin treatment or gamma-irradiation of human diploid fibroblasts was studied by the alkaline elution technique. DNA rejoining occurred at slower rates in bleomycin-treated human fibroblasts than in gamma-irradiated fibroblasts. These comparisons were made at similar levels of survival or DNA single-strand breaks (including alkali-labile lesions). Significant numbers of DNA single-strand breaks were detected routinely after 2 micrograms/ml (1.34 X 10(-6) M) bleomycin treatments (for 30 min, survival greater than 70%). Dose-dependent losses of approximately 3 to 15% of total radioactivity were measured in preelution samples from cells treated with bleomycin (2 to 100 micrograms/ml), but only 2 to 3.5% of total radioactivity was assayed in lysis samples from cells irradiated with 200 to 1000 rads. This result suggests that DNA was more degraded by or after bleomycin treatment. DNA was rejoined extremely rapidly after bleomycin or radiation treatments, and the rejoining was both agent- and dose-dependent. Over dose ranges yielding surviving fractions of 75 to 0.056%, considerable DNA rejoining occurred after only 2.5 min posttreatment incubation in conditioned medium. Cellular recovery occurred at faster rates after bleomycin treatments than after gamma-irradiation, while DNA rejoining occurred at faster rates after gamma-irradiation, thus uncoupling DNA repair and cellular recovery in relating the cellular action of these 2 agents. No consistent differences were observed among 3 normal fibroblast strains and fibroblasts from a Gardner's syndrome patient (deficient in their capacity for cellular recovery) or a Turcot's syndrome patient in the formation and rejoining of single-strand breaks after bleomycin or radiation treatments.

Adult↗
PubMed1984

On the use of oxytetracycline in reducing the incidence of metritis in dairy cows.

50 dairy cows were alternately either given no perinatal treatment or were given an intramuscular injection of oxytetracycline in a 2-pyrrolidone base at a dosage rate of 20 mg/kg body mass. The incidence of metritis in the untreated (control) group was 46 out of 120 cows (38,3%), while in the treated group there were 30 metritis cows out of 130 (23%)--a statistically significant difference.

Animals↗
PubMed1983

Prediction of Wiggins content scale scores from 168- and 399-item abbreviations of the MMPI.

Multiple regression equations for estimating Wiggins content scores from 399- and 168-item abbreviations of Form R of the Minnesota Multiphasic Personality Inventory (MMPI) were derived for 100 patients and cross-validated in a separate sample of 50 patients. Across samples, Rs between 399-item short form scales and corresponding full scales were very high (median = .98 for the total sample), and the equations predicted accurately in cross-validation. Rs in estimating from 168 items were lower (median = .91 for the total sample), but the equations estimated mean content scores well in cross-validation. These results were viewed as indicating that there may be little loss in estimating from 399 items but that error in prediction may be unacceptably high for some of the 168-item short form scales. The correspondence of Wiggins scales and standard MMPI scales was also studied through regression analyses, and it was concluded that, although there is considerably overlap in the two sets of scales, inferences as to self-report content from the standard scales are not always simple or especially accurate.

Adult↗
PubMed1982

Modulation of bleomycin cytotoxicity.

Lethal effects of a 75-microgram/ml concentration (approximately 5 X 10-5 M) of bleomycin on stationary-phase haploid or diploid cells of the eucaryote Saccharomyces cerevisiae were negated in the presence of 0.05 M phosphate buffer (pH 7). High cell densities (2 X 10(8) cells per ml) further inhibited killing. Multiphasic survival curves resulting after treatments in deionized water (pH 6.7) suggested the presence of cells with differing susceptibilities either at the start of treatment periods or as a result of resistance which developed during exposure to antibiotic. To identify a delayed effect, prolonged lethal consequences of the action of bleomycin were investigated under liquid-holding conditions. Survival of untreated early-stationary-phase yeast cells was not significantly affected by incubation without antibiotic for 6 or 36 h in non-nutrient buffer or water. However, increased killing resulted after bleomycin-treated cells were incubated in the absence of bleomycin or buffer. Moreover, cells which had never been exposed to the antibiotic lost considerable colony-forming ability as a result of incubation with bleomycin-treated cells, indicating the efflux of bleomycin or a reaction product. The findings have implications for both experimental cell studies and cancer therapy, as well as for the chemical mechanisms by which a metal bleomycin complex could cause killing.

Bleomycin↗
PubMed1982

Ligase-deficient yeast cells exhibit defective DNA rejoining and enhanced gamma ray sensitivity.

Yeast cells deficient in DNA ligase were also deficient in their capacity to rejoin single-strand scissions in prelabeled nuclear DNA. After high-dose-rate gamma irradiation (10 and 25 krads), cdc9-9 mutant cells failed to rejoin single-strand scissions at the restrictive temperature of 37 degrees C. In contrast, parental (CDC9) cells (incubated with mutant cells both during and after irradiation) exhibited rapid medium-independent DNA rejoining after 10 min of post-irradiation incubation and slower rates of rejoining after longer incubation. Parental cells were also more resistant than mutant cells to killing by gamma irradiation. Approximately 2.5 +/- 0.07 and 5.7 +/- 0.6 single-strand breaks per 10(8) daltons were detected in DNAs from either CDC9 or cdc9-9 cells converted to spheroplasts immediately after 10 and 25 krads of irradiation, respectively. At the permissive temperature of 23 degrees C, the cdc9-9 cells contained 2 to 3 times the number of DNA single-strand breaks as parental cells after 10 min to 4 h of incubation after 10 krads of irradiation, and two- to eightfold more breaks after 10 min to 2.5 h of incubation after 25 krads of irradiation. Rejoining of single-strand scissions was faster in medium. After only 10 min in buffered growth medium and after 10 krads of irradiation, the number of DNA single-strand breaks was reduced to 0.32 +/- 0.3 (at 23 degrees C) or 0.21 +/- 0.05 (at 37 degrees C) per 10(8) daltons in parental cells, but remained at 2.1 +/- 0.06 (at 23 degrees C) or 2.3 +/- 0.07 (at 37 degrees C) per 10(8) daltons in mutant cells. After 10 or 25 krads of irradiation plus 1 h of incubation in medium at 37 degrees C, only DNA from CDC9 cells was rejoined to the size of DNA from unirradiated cells, whereas at 23 degrees C, DNAs in both strains were completely rejoined.

Culture Media↗
PubMed1982

cdc9 ligase-defective mutants of Saccharomyces cerevisiae exhibit lowered resistance to lethal effects of bleomycin.

Conditional ligase-deficient mutants of Saccharomyces cerevisiae were more sensitive than their parental (CDC9) strain to dose-dependent killing by bleomycin, even when mutant cells were pregrown and exposed to the antibiotic at permissive temperatures. Pretreatment incubation at the restrictive temperature (37 degrees C) under growing or nongrowing conditions enhanced bleomycin killing of both cdc9-1 and cdc9-9 mutants. This sensitization could be relieved by incubation at the permissive temperature before treatment.

Bleomycin↗
PubMed1982

Control of in vivo (cellular) phleomycin sensitivity by nuclear genotype, growth phase, and metal ions.

Nuclear genotype, growth phase, and the presence of metal ions all proved to be important in controlling the lethal effects of phleomycin in eukaryotic Saccharomyces cerevisiae. Among 120 normal and radiation-sensitive strains compared for their sensitivities to lethal effects of phleomycin, all mutant strains exhibiting enhanced sensitivities to phleomycin killing were also sensitive to killing by ionizing radiation. Mutants exhibiting sensitivities to phleomycin similar to normal strains of the same ploidy were sensitive to ultraviolet radiation. We conclude that cellular recovery from phleomycin-induced damage in yeast depends upon the function of some or all of 13 independent genes and upon at least some of the same steps in cellular pathways for the biological repair of damage by ionizing radiation. In this respect, the action of phleomycin is similar to the action of its structurally similar analog, bleomycin, even though phleomycin was substantially more cytotoxic. Stationary-phase haploid yeast cells were more sensitive than exponentially growing cells to killing by phleomycin. Survival of stationary-phase yeast was reduced to 0.3 +/- 0.07% (S.E.) after 20-min exposures to phleomycin (1 microgram/ml; approximately 6.7 x 10(-7) M), but lethal effects of phleomycin were completely eradicated (98% survival) by the presence of 0.05 M ethylenediaminetetraacetate during the treatment period. The inactivation indicates an important role for one or more metal ion(s) in the in vivo toxicity of the phleomycin-bleomycin group of anticancer antibiotics.

Bleomycin↗
PubMed1980

Influence of pH and length of post-treatment incubation on bleomycin-induced DNA damage.

The dependence of the extent of DNA damage by anticancer bleomycin on pH and length of post-treatment incubation was studied in yeast. Bleomycin was always removed from cells after 20-min exposures, and cells were washed prior to incubation in non-nutrient buffer. Following exposures of late stationary-phase cells to the very low dose of only 3 micrograms/ml, 1.5 h incubation in non-nutrient buffer, pH 5, had hardly any effect on profiles derived from alkaline sucrose gradient sedimentation of nucleic acids released from spheroplasts. In contrast, after incubation of cells for 1.5 h in buffer, pH 7, DNA was all low molecular weight. Thus, even after extensive washing of cells, pH strongly influences the drug's action on DNA. At pH 5, washed cells were increasingly susceptible to DNA damage up to 26 h in non-nutrient buffer.

Bleomycin↗