Biomedical subjects

M M Moore

Publications and source records attributed to M M Moore.

At least 19 recordsLinked to original sources

PubMed1995

Acrylamide: a review of its genotoxicity and an assessment of heritable genetic risk.

An updated review of the genotoxicity studies with acrylamide is provided. Then, using data from the studies generating quantitative information concerning heritability of genetic effects, an assessment of the heritable genetic risk presented by acrylamide is presented. The review offers a discussion of the reactions and possible mechanisms of genotoxic action by acrylamide and its epoxide metabolite glycidamide. Several genetic risk approaches are discussed, including the parallelogram, direct (actually a modified direct), and doubling dose approaches. Using data from the specific-locus and heritable translocation assays, the modified direct and doubling dose approaches are utilized to quantitate genetic risk. Exposures of male parents to acrylamide via inhalation, ingestion, and dermal routes are also quantitated. With these approaches and measurements and their underlying assumptions concerning extrapolation factors (including germ cell stage specificity, DNA repair variability, locus specificity), number of human loci associated with dominant disease alleles, and spontaneous mutation rates, an assessment of heritable genetic risk for humans is calculated for the three exposure scenarios. The calculated estimates for offspring from fathers exposed to acrylamide via drinking water are up to three offspring potentially affected with induced genetic disease per 10(8) offspring. Estimates for inhalation or dermal exposures suggest higher risks for induced genetic disease in offspring from fathers exposed in occupational settings.

Acrylamide↗

PubMed1995

Germ line specific factors in chemical mutagenesis.

Chemical mutagenesis test results have not revealed evidence of germ line specific mutagens. However, conventional assays have indicated that there are male-female differences in mutagenic response, as well as quantitative/qualitative differences in induced mutations which depend upon the particular cell stage exposed. Many factors inherent in the germ line can be speculated to influence chemical transport to, and interaction with, target cell populations to result in mutagenic outcomes. The level of uncertainty regarding the general operation of such factors, in combination with the limited availability of chemical test data designed to address comparative somatic and germ cell mutagenesis, leaves open the question of whether there are mutagens specifically affecting germ cells. This argues for a conservative approach to interpreting germ cell risk from somatic cell mutation analysis.

Animals↗

PubMed1994

Cytotoxic T-lymphocyte response to autologous human squamous cell cancer of the lung: epitope reconstitution with peptides extracted from HLA-Aw68.

Cytotoxic T-lymphocytes (CTLs) specific for autologous human squamous cell cancer of the lung were generated by stimulation of peripheral blood lymphocytes with autologous tumor cells in vitro. The CTL line was >97% CD3+, CD8+, CD16- and produced tumor necrosis factor-alpha, gamma-interferon, and granulocyte-macrophage colony-stimulating factor after stimulation with autologous tumor. The CTLs lysed autologous tumor but failed to recognize autologous or histocompatibility leukocyte antigen-matched lymphoid cells, K562, or allogeneic tumor cells of several histological types. Antibody-blocking studies suggested that the CTLs recognized one or more antigens presented by the class I major histocompatibility complex molecule Aw68. To characterize these antigens further, histocompatibility leukocyte antigen Aw68 molecules were extracted from the squamous cell cancer of the lung tumor line by immunoaffinity chromatography, and the associated peptides were eluted in acid and separated by reversed-phase high-performance liquid chromatography. Reconstitution of the CTL epitope was evaluated by adding these peptides to autologous Epstein-Barr virus-transformed B-cells. Two peaks of reconstituting activity were observed, suggesting that these CTLs recognize at least two Aw68-associated peptides. This study confirms the existence of a CTL response against autologous human squamous cell cancer of the lung and suggests that this CTL response is directed against peptide epitopes presented by the class I major histocompatibility complex molecules. It is anticipated that this approach will permit identification of peptide epitopes for lung cancer-specific CTLs.

Carcinoma, Squamous Cell↗

PubMed1993

Genotoxicity of three pyridine compounds to L5178Y mouse lymphoma cells.

The L5178Y mouse lymphoma assay was used to examine the potential mutagenicity of three halogenated pyridine compounds. Position effects of the halogen moiety and the role of metabolic activation were analyzed based on induced mutant frequency, gross chromosome aberrations, and micronuclei. Without activation, 2-chloropyridine, 3-chloropyridine, and 2-chloro-5-trifluoromethylpyridine produced a small increase in mutant frequency; only the 2-chloropyridine activity was significantly increased with activation. All three compounds were also clastogenic as demonstrated by increases in chromosome aberrations and micronuclei (except for 2-chloro-5-trifluoromethylpyridine which did not induce micronuclei either with or without activation).

Animals↗

PubMed1992

In vitro mammalian mutagenesis as a model for genetic lesions in human cancer.

Recently in vitro assays of mutagenesis have been criticized as being poorly predictive of long-term in vivo rodent assays of carcinogenicity. Questions have also been raised concerning the relevance of rodent assays to human risk. In vitro assays using mammalian cells can detect most types of genetic lesions thought to be important in human malignant disease. Molecular and cytogenetic analyses of mutations induced by a variety of genotoxic compounds at the heterozygous thymidine kinase locus in mouse lymphoma cells indicate that this in vitro assay does indeed register the range of genetic lesions recently found in a wide variety of human tumors. The types and complexity of the induced lesions are reflected in mutant colony phenotype in a compound-specific fashion. These studies point to the use of appropriate in vitro mammalian mutagenesis assays as new model systems for dissecting the genetic lesions important in human carcinogenesis, and as a means of determining the potential for compounds to induce such lesions.

Animals↗

PubMed1992

Large deletions are tolerated at the hprt locus of in vivo derived human T-lymphocytes.

A cloning assay was used to recover hprt- T-lymphocytes from adult human males. Analysis of crude cellular extracts by polymerase chain reactions (PCRs) demonstrated that 7% (16/218) of the hprt mutations were due to total deletion of the hprt gene. 14 of the 16 mutants were examined by PCR for the presence of flanking DNA to determine the extent of the deletions. The deletion mutation in 13 mutants was at least 350 kb with 5 of these deletions being at least 700 kb. The largest deletions were greater than 15 times the size of the hprt gene. Therefore, large deletions are tolerated at the hprt locus of human T-lymphocytes.

Adult↗

PubMed1992

V(D)J recombinase-mediated deletion of the hprt gene in T-lymphocytes from adult humans.

The hprt T-cell cloning assay allows the detection of mutations occurring in vivo in the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene of T-lymphocytes. We have shown previously that the illegitimate activity of V(D)J recombinase accounts for about 40% of the hprt mutations in T-lymphocytes of human newborns as measured with umbilical cord blood samples (Fuscoe et al., 1991). This mechanism results in deletion of hprt exons 2 + 3. In this report, we examined a collection of 314 HPRT-deficient clones derived from adult humans for evidence that the mutations were caused by this mechanism by analyzing exons 2 + 3 deletion mutations. DNA sequence analysis of deletion breakpoint junctions showed that 8 of the mutations were the result of V(D)J recombinase activity. The frequency of the recombinase-mediated mutations was similar in the adults and newborns (2-4 x 10(-7). However, since the hprt mutant frequency is about 10-fold higher in the adult than in the newborn, the recombinase-mediated mutations account for only a few percent of the adult mutations. These mutations are likely to have occurred during early development and persist into adulthood. Unregulated expression of V(D)J recombinase activity may be an important mechanism for genomic rearrangements in the genesis of cancer.

Adult↗

PubMed1992

Synthetic trehalose dicorynomycolate and antimicrobials increase survival from sepsis in mice immunocompromised by radiation and trauma.

When mammalian antimicrobial defenses are compromised by radiation, death from sepsis may occur. Tissue trauma in irradiated hosts significantly increases mortality from bacterial infections and makes antimicrobial treatments more difficult than when individuals are subjected to trauma or radiation alone. We determined that postirradiation therapy with the immunomodulator synthetic trehalose dicorynomycolate (S-TDCM) and antimicrobials increases survival in mice after lethal irradiation and tissue trauma. Single agent therapy with systemic oxacillin, gentamicin, ofloxacin, and S-TDCM did not increase survival. Topical treatment of the injury with gentamicin cream in addition to systemic therapy with oxacillin or S-TDCM was necessary to enhance survival. Therapy with gentamicin and S-TDCM had a synergistic effect on survival. Therapies combining augmentation of non-specific host defense mechanisms with antimicrobials may be valuable in treating irradiated patients also sustaining tissue trauma.

Animals↗

PubMed1991

Considerations in the U.S. Environmental Protection Agency's testing approach for mutagenicity.

OPP: This paper provides the rationale and support for the decisions the OPP will make in requiring and reviewing mutagenicity information. The regulatory requirement for mutagenicity testing to support a pesticide registration is found in the 40 CFR Part 158. The guidance as to the specific mutagenicity testing to be performed is found in the OPP's Pesticide Assessment Guidelines, Subdivision F, Hazard Evaluation: Human and Domestic Animals (referred to as the Subdivision F guideline). A revised Subdivision F guideline has been presented that becomes the current guidance for submitters of mutagenicity data to the OPP. The decision to revise the guideline was the result of close examination of the version published in 1982 and the desire to update the guidance based on developments since then and current state-of-the-science. After undergoing Agency and public scrutiny, the revised guideline is to be published in 1991. The revised guideline consists of an initial battery of tests (the Salmonella assay, an in vitro mammalian gene mutation assay and an in vivo cytogenetics assay which may be either a bone marrow assay for chromosomal aberrations or for micronuclei formation) that should provide an adequate initial assessment of the potential mutagenicity of a chemical. Follow-up testing to clarify results from the initial testing may be necessary. After this information as well as all other relevant information is obtained, a weight-of-evidence decision will be made about the possible mutagenicity concern a chemical may present. Testing to pursue qualitative and/or quantitative evidence for assessing heritable risk in relation to human beings will then be considered if a mutagenicity concern exists. This testing may range from tests for evidence of gonadal exposure to dominant lethal testing to quantitative tests such as the specific locus and heritable translocation assays. The mutagenicity assessment will be performed in accordance with the Agency's Mutagenicity Risk Assessment Guidelines. The mutagenicity data would also be used in the weight-of-evidence consideration for the potential carcinogenicity of a chemical in accordance with the Agency's Carcinogen Risk Assessment Guidelines. In instances where there are triggers for carcinogenicity testing, mutagenicity data may be used as one of the triggers after a consideration of available information. It is felt that the revised Subdivision F guideline will provide appropriate, and more specific, guidance concerning the OPP approach to mutagenicity testing for the registration of a pesticide. It also provides a clearer understanding of how the OPP will proceed with its evaluation and decision making concerning the potential heritable effects of a test chemical.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1991

Genotoxicity of 2-amino-6-N-hydroxyadenine (AHA) to mouse lymphoma and CHO cells.

2-Amino-6-N-hydroxyadenine (AHA) treated L5178Y/TK (+/-)-3.7.2C mouse lymphoma cells were evaluated for mutations at the tk, hgprt, and Na+/K+ ATPase loci, as well as for gross chromosome aberrations and induction of micronuclei. In addition, AHA was evaluated for its ability to induce HGPRT mutants in CHO cells. AHA was found to induce mutations at all evaluated loci and in both cell types. The TK mutants were primarily large colonies although a few small colonies were also induced, particularly at the higher concentrations. Preliminary cytogenetic analysis of AHA-treated mouse lymphoma cells indicated that some gross aberrations but not micronuclei were induced. The 20 small-colony TK mutants evaluated by banded karyotype indicate that only a small fraction (2 of 20) showed chromosome 11 abnormalities. From these studies, it appears that AHA may be one of a very few chemicals that is capable of inducing multi-locus point mutations, with only slight clastogenic activity. Particularly at the higher concentrations, some of the mutants may contain multi-locus point mutations that result in slow growth.

Adenine↗

PubMed1991

Localization of the mouse thymidine kinase gene to the distal portion of chromosome 11.

We report the cytogenetic mapping of the thymidine kinase (tk-1) gene in the mouse using two complementary and independent analyses: (1) investigation of chromosome aberrations associated with tk-1 gene inactivation in the L5178Y TK+/- -3.7.2C cell line, and (2) fluorescence in situ molecular hybridization of cloned tk-1 cDNA probes to mitotic chromosomes of this cell line. The consensus location from both analyses is 11E1-E2. Consideration of the mouse tk-1 gene localization, along with evidence that the homologous human TK1 gene is located distally on the large arm of chromosome 17, appears to extend the region of homology between MMU11 and HSA17 to the distal end of both chromosomes.

Animals↗

PubMed1991

Analysis of the genotoxicity of anthraquinone dyes in the mouse lymphoma assay.

Despite their widespread use and potential for significant human exposure, genotoxicity data on anthraquinones and other dyes are limited. In this study, 16 anthraquinones and one azo dye (Solvent Red 1) were selected for testing using the thymidine kinase (tk) locus and micronucleus (MN) analysis in L5178Y/TK(+/-)-3.7.2C mouse lymphoma cells. Six of the dyes were from the same lot used in the NTP rodent bioassay. The dyes used were all production lots and thus varied in their purity. Disperse Blue 7, 2-aminoanthraquinone, 1-amino-2-methylanthraquinone, Disperse Blue 3 and Disperse Red 11 were genotoxic (inducing 1814 mutants/10(6) survivors, 369 MN/1000 cells at 13% survival; 397 mutants/10(6) survivors, 196 MN/1000 cells at 21% survival; 178 mutants/10(6) survivors, 119 MN/1000 cells at 51% survival; 264 mutants/10(6) survivors, 109 MN/1000 cells at 15% survival, respectively). Reactive Blue 19 was weakly mutagenic (inducing 144 mutants/10(6) survivors, but only 8 MN/1000 cells at 13% survival). Vat Yellow 4 and Solvent Red 1, with exogenous activation, were also mutagenic (inducing 300 mutants/10(6) survivors, 18 MN/1000 cells at 57% survival, and 100 mutants/10(6) survivors and 16 MN/1000 cells at 22% survival, respectively). With activation 1-nitro-2-methylanthraquinone was judged to give an equivocal mutagenicity response. The maximum test concentration was limited for some compounds by their solubility. Those chemicals that did not induce mutation or cytotoxicity at the limits of solubility were classified separately. Compounds which were not evaluated without exogenous activation because of insolubility but were evaluated with activation include 1-nitro-2-methylanthraquinone, Solvent Red 1 and Vat Yellow 4. Compounds which were not evaluated either with or without S9 activation because of their insolubility in the culture medium include 1-amino-2,4-dibromoanthraquinone, D&C Green, Disperse Blue 1, Disperse Red 60, Vat Blue 4, Vat Blue 20, Vat Brown 1 and Vat Brown 3.

Animals↗

PubMed1991

Comparison of mutagenicity results for nine compounds evaluated at the hgprt locus in the standard and suspension CHO assays.

The Chinese hamster ovary (CHO) assay, which measures newly induced mutations at the hypoxanthine-guanine phosphoribosyltransferase (hgprt) locus, has been widely used for mutagenesis testing. The insensitivity of the standard assay to some genotoxic agents has been speculated to be due to the relatively small number of cells used in the assay. In the present study, we have compared the standard monolayer assay with a suspension adapted CHO assay that uses cell numbers comparable to that of the L5178Y mouse lymphoma assay. Nine compounds, ethyl methanesulfonate (EMS), methyl methanesulfonate (MMS), 2-methoxy-6-chloro-9-[3-(ethyl-2-chloroethyl)-aminopropylamino]-acridine 2HCl (ICR 170), methyl acrylate, ethyl acrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, 2-ethylhexyl acrylate and dicyclopentenyloxyethyl methacrylate were evaluated in the monolayer and suspension assays. Both assays gave the same overall qualitative results for the test compounds. There were some quantitative differences in the mutant frequency for the three compounds found to be mutagenic (EMS, MMS and ICR 170). The acrylates (many of which appear to exert their genotoxic effect through a clastogenic mechanism) were negative in both test systems. The use of the suspension assay did not improve the ability of the hgprt locus to detect the genotoxicity of the acrylates. Thus, increasing the number of cells does not improve the ability of the CHO/HGPRT assay to detect compounds that act primarily by a clastogenic mechanism.

Acrylates↗

PubMed1991

Genotoxicity in mouse lymphoma cells of chemicals capable of Michael addition.

Over the past several years, we have been evaluating the mutagenicity and clastogenicity of compounds capable of Michael-type reactions. These compounds, including acrylamide, several acrylate and methacrylate esters, vinyl sulfones, and phorone, have been evaluated using TK+/- -3.7.2C mouse lymphoma cells. Mutagenic chemicals induced increases in the number of small colony tk- deficient mutants. This suggested a clastogenic mechanism which was confirmed by demonstrating increases in aberrations and micronucleus frequencies in cultured cells. Vinyl sulfone was found to be the most effective chemical mutagen with induction of genotoxic effects at concentrations as low as 0.25 microgram/ml. The other compounds also produced positive results, but at higher concentrations. Since these compounds are known to deplete glutathione, phorone, a model glutathione depleter, was examined and found to produce similar effects as the other compounds in mouse lymphoma cells. These results suggest that the direct-acting Michael-type reaction has activity relevant to producing a genotoxic effect. Since acrylamide has been found to be a potent germ cell mutagen, this mechanism may be also relevant in the induction of heritable mutagenic risk.

Acrylates↗

PubMed1991

Treatment of mice with sepsis following irradiation and trauma with antibiotics and synthetic trehalose dicorynomycolate (S-TDCM).

Compromise of antimicrobial defenses by irradiation can result in sepsis and death. Additional trauma can further predispose patients to infection and thus increase mortality. We recently showed that injection of synthetic trehalose dicorynomycolate (S-TDCM) significantly augments resistance to infection and increases survival of mice compromised either by whole-body irradiation with gamma radiation or equal mixtures of fission neutron and gamma radiation. In this study, C3H/HeN mice were given a lethal dose of gamma radiation (8.0 Gy) and an open wound (15% total body surface area [TBSA]) 1 hr later while anesthetized. Irradiated/wounded mice became more severely leukopenic and thrombocytopenic than mice exposed to radiation alone, and died from natural wound infection and sepsis within 7 days. S-TDCM given 1 hr postirradiation increased survival of mice exposed to radiation alone. However, this treatment did not increase survival of the irradiated/wounded mice. Systemic antibiotic therapy with gentamicin or ofloxacin for 10 days significantly increased survival time compared with untreated irradiated/wounded mice (p less than 0.01). Combination therapy with topical gentamicin cream and systemic oxacillin increased survival from 0% to 100%. Treatment with S-TDCM combined with the suboptimal treatment of topical and systemic gentamicin increased survival compared with antibiotic treatment alone. These studies demonstrate that post-trauma therapy with S-TDCM and antibiotics augments resistance to infection in immunocompromised mice. The data suggest that therapies which combine stimulation of nonspecific host defense mechanisms with antibiotics may increase survival of irradiated patients inflicted with accidental or surgical trauma.

Administration, Topical↗

PubMed1991

Therapy of infections in mice irradiated in mixed neutron/photon fields and inflicted with wound trauma: a review of current work.

When host antimicrobial defenses are severely compromised by radiation or trauma in conjunction with radiation, death from sepsis results. To evaluate therapies for sepsis in radiation casualties, we developed models of acquired and induced bacterial infections in irradiated and irradiated-wounded mice. Animals were exposed to either a mixed radiation field of equal proportions of neutrons and gamma rays (n/gamma = 1) from a TRIGA reactor or pure gamma rays from 60[Co sources. Skin wounds (15% of total body surface area) were inflicted under methoxyflurane anesthesia 1 h after irradiation. In all mice, wounding after irradiation decreased resistance to infection. Treatments with the immunomodulator synthetic trehalose dicorynomycolate (S-TDCM) before or after mixed neutron-gamma irradiation or gamma irradiation increased survival. Therapy with S-TDCM for mice irradiated with either a mixed field or gamma rays increased resistance to Klebsiella pneumoniae-induced infections. Combined therapy with S-TDCM and ceftriaxone for K. pneumoniae infections in mice exposed to a mixed radiation field or to gamma rays was more effective than single-agent therapy. In all irradiated-wounded mice, single therapy of acquired infections with an antibiotic or S-TDCM did not increase survival. Survival of irradiated-wounded mice after topical application of gentamicin sulfate cream suggested that bacteria colonizing the wound disseminated systemically in untreated irradiated mice, resulting in death from sepsis. In lethal models of acquired infections in irradiated-wounded mice, significant increases in survival were achieved when systemic treatments with S-TDCM or gentamicin were combined with topical treatments of gentamicin cream. Therapies for sepsis in all mice exposed to a mixed field were less effective than in mice exposed to gamma rays. Nonetheless, the data show a principle by which successful therapy may be provided to individuals receiving tissue trauma in conjunction with radiation injury.

Adjuvants, Immunologic↗

PubMed1990

Molecular dissection of mutations at the heterozygous thymidine kinase locus in mouse lymphoma cells.

The mouse lymphoma L5178Y TK+/- 3.7.2C cell line allows quantitation of induced TK(+/-)----TK-/- mutations at the heterozygous thymidine kinase (Tk) locus. TK-/- mutant colonies show a bimodal size distribution, reflecting a difference in the growth rates of the two size classes that is hypothesized to result from different degrees of genetic damage. The two homologous chromosomes 11 containing the alleles of the Tk gene in L5178Y 3.7.2C TK+/- cells are distinguishable at the cytogenetic level. We find, in addition, that the two alleles are distinguishable at the molecular level because of an Nco I restriction fragment length polymorphism at the 3' end of the gene. In a set of 51 large-colony and 48 small-colony TK-/- mutants induced by ionizing radiation or by chemical mutagens, we find that 78, including all except one of the small-colony mutants, have lost the Tk+ allele and that some of these have two to four copies of the remaining Tk- allele. Nineteen of the large-colony TK-/- mutants that do not show Tk+ allele loss show no other structural changes detectable at the level of Southern blot analysis. One shows a partial deletion. The variety of mutagenic lesions recorded at the heterozygous Tk locus may be representative of events observed in human malignancy and may include a wider range of mutagenic events than can be observed at hemizygous test loci.

Alleles↗

PubMed1990

Genotoxicity of inhibitors of DNA topoisomerases I (camptothecin) and II (m-AMSA) in vivo and in vitro.

The present study was designed to determine and compare the clastogenicity of m-AMSA and camptothecin (CAMP) in vivo in mouse bone marrow and peripheral blood lymphocytes (PBLs), and in vitro in mouse lymphoma L5178Y cells. m-AMSA interferes with topoisomerase II to induce double-strand DNA breaks. CAMP interferes with topoisomerase I to induce single-strand DNA breaks. Thus, we expected the two drugs to induce different types of chromosomal aberrations (CAs). However, both drugs produced quantitatively and qualitatively similar numbers and types of aberrations under similar experimental conditions. In mouse bone marrow exposed over and 18-h period, both drugs (3 mg/kg) induced approximately 30 damaged cells, with an average of 0.4 chromatid breaks per cell (in 100 cells analyzed/mouse). In addition, both drugs induced only chromatid-type aberrations in mouse bone marrow in vivo when exposure occurred during G2. Cell cycle specificity was indicated by the absence of CAs when exposure to the drugs occurred in vivo in mouse PBLs during G0. In L5178Y cells, m-AMSA was considerably more potent for the induction of mutations and somewhat more potent for the induction of CAs than CAMP was. In contrast to the in vivo bone marrow results, the drugs induced high levels of both chromatid- and chromosome-type aberrations in vitro. The ultimate types of chromosomal damage induced by m-AMSA and CAMP result from a complex interaction of (i) cell cycle specific variations in topoisomerase enzyme levels, (ii) the abilities of these drugs to interfere with the orderly DNA breakage/reunion associated with topoisomerase activity, and (iii) the processing of the damage resulting from these interactions.

Amsacrine↗