AccuCount - Published Papers
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| Article No. | Title |
| CLC1031 | Differential Induction of Gamma Interferon in Legionella pneumophila-Infected Macrophages from BALB/c and A/J Mice |
| SHELDON SALINS, CATHERINE NEWTON,* RAY WIDEN, THOMAS W. KLEIN, AND HERMAN FRIEDMAN | |
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Gamma interferon (IFN-g), a pleiotropic cytokine, is now known to be produced by macrophages as well as by NK cells, gd cells, and activated T cells. The autocrine biological functions of IFN-g on the macrophage include the upregulation of major histocompatibility complex MHC class II and the activation to an antiviral state. In this study, the production of IFN-g by macrophages was demonstrated to correspond to antibacterial activity. Legionella pneumophila replicates intracellularly in thioglycolate (TG)-elicited macrophages (TGmacrophages) from A/J mice, while TG-macrophages from BALB/c mice restrict bacterial growth after an initial period of growth. BALB/c TG-macrophages were shown to express IFN-g mRNA at 24 and 28 h, which corresponded to the initiation of anti-L. pneumophila activity. Moreover, IFN-gneutralization by antibody treatment of the cultures resulted in increased L. pneumophila growth in the macrophages. In contrast, no IFN-g mRNA was expressed in TG-macrophages from A/J mice, where L. pneumophila grew unrestricted. As would be expected, IFN-g treatment decreased bacterial growth. An IFN-g-mediated antibacterial activity was, however, inducible in A/J macrophages by the addition of interleukin-12 following L. pneumophila infection. Thus, autocrine IFN-g is involved in anti-L. pneumophila activity associated with different growth patterns and appears to be important during intracellular infection. |
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| CLC1032 | Comparison of the Cytotoxic and Mutagenic Potential of Liquid Smoke Food Flavourings, Cigarette Smoke Condensate and Wood Smoke Condensate |
| K. P. PUTNAM, D. W. BOMBICK, J. T. AVALOS AND D. J. DOOLITTLE | |
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Although products of pyrolysis are often cytotoxic and mutagenic, the relationship between the type of material pyrolysed and the toxicity of the resulting pyrolysis products is poorly understood. The objective of this study was to evaluate and compare the cytotoxicity and mutagenicity of several types of common pyrolysis products. The cytotoxicity and mutagenicity of these products were assessed by using neutral red uptake and Ames mutagenicity assays, respectively. The biological activities of four liquid smoke food Pavourings (LSF) were compared with two other pyrolysis-derived materials; cigarette smoke condensate (CSC) and a wood smoke condensate (WSC). Results indicated all of the mixtures exhibited a concentration-dependent cytotoxic response. The CSC and WSC were less cyto-toxic than three of the LSFs, but more cytotoxic than one of the brands. The CSC was mutagenic in two Salmonella strains; however, none of the LSFs or WSC was mutagenic using TA98, and only three of the LSFs were positive with TA100. The six pyrolysis-derived materials evaluated in this study showed differing patterns and magnitudes of cytotoxicity and mutagenicity. |
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| CLC1033 | Effects of Chicken-Derived Cecal Microorganisms Maintained in Continuous Culture on Cecal Colonization by Salmonella typhimurium in Turkey Poults |
| A. G. HOLLISTER, D. E. CORRIER, D. J. NISBET,AND J. R. DELOACH | |
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A characterized, chicken-derived, competitive exclusion culture of cecal bacteria was evaluated for effectiveness in the reduction of Salmonella typhimurium cecal colonization in growing turkey poults. The culture was administered by crop gavage on the day of hatch. All groups were challenged orally on Day 3 with 104 S. typhimurium. Compared with untreated controls, the percentage of poults that were Salmonella cecalculture-positive at 10 d of age was significantly reduced (P < 0.05) in the poults provided culture. Additionally, the culture-treated poults had significantly (P < 0.05) fewer Salmonella per gram of cecal contents than the controls. The results indicated that treatment of turkey poults with the characterized chicken-derived culture effectively decreased Salmonella cecal colonization. |
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| CLC1034 | Inhibition of spontaneous mutagenesis by vanillin and cinnamaldehyde in Escherichia coli: Dependence on recombinational repair |
| DANIEL T. SHAUGHNESSYA, ROEL M. SCHAAPERB, DAVID M. UMBACHC, and DAVID M. DEMARINID | |
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Vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutagens that effectively inhibit both induced and spontaneous mutations. We have shown previously that VAN and CIN reduced the spontaneous mutant frequency in Salmonella TA104 (hisG428, rfa, ΔuvrB, pKM101) by approximately 50% and that both compounds significantly reduced mutations at GC sites but not at AT sites. Previous studies have suggested that VAN and CIN may reduce mutations in bacterial model systems by modulating DNA repair pathways, particularly by enhancing recombinational repair. To further explore the basis for inhibition of spontaneous mutation by VAN and CIN, we have determined the effects of these compounds on survival and mutant frequency in five Escherichia coli strains derived from the wild-type strain NR9102 with different DNA repair backgrounds. At nontoxic doses, both VAN and CIN significantly reduced mutant frequency in the wild-type strain NR9102, in the nucleotide excision repair-deficient strain NR11634 (uvrB), and in the recombination-proficient but SOS-deficient strain NR11475 (recA430). In contrast, in the recombination-deficient and SOS-deficient strain NR11317 (recA56), both VAN and CIN not only failed to inhibit the spontaneous mutant frequency but actually increased the mutant frequency. In the mismatch repair-defective strain NR9319 (mutL), only CIN was antimutagenic. Our results show that the antimutagenicity of VAN and CIN against spontaneous mutation required the RecA recombination function but was independent of the SOS and nucleotide excision repair pathways. Thus, we propose the counterintuitive notion that these antimutagens actually produce a type of DNA damage that elicits recombinational repair (but not mismatch, SOS, or nucleotide excision repair), which then repairs not only the damage induced by VAN and CIN but also other DNA damage—resulting in an antimutagenic effect on spontaneous mutation. |
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