Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| mutagenicity of nitric oxide and its inhibition by antioxidants. | nitric oxide (no) is produced both by macrophages in vivo as a physiological response to infection and by a variety of cell types as an intercellular messenger. in addition, no and nitrogen dioxide (no2) are significant components of many combustion processes. the ubiquitous exposure of humans to nitrogen oxides (nox), both endogenously and exogenously, may play a significant role in the carcinogenic process due to nitrosation of amines by nox. we report here that exposure to low concentrations ... | 1992 | 1371842 |
| the role of the excision and error-prone repair systems in mutagenesis by fluorinated quinolones in salmonella typhimurium. | patterns of reversion produced by ciprofloxacin, enoxacin and ofloxacin in salmonella typhimurium strains carrying the hisg428 ochre mutation have been studied. these fluorinated quinolones produce a significant increase in reversion of this mutation, even when it is located on the chromosome. nevertheless, reversion is higher when the hisg428 mutation is on the multicopy plasmid paq1 than when it is on the chromosome. reversion of hisg428 induced by fluorinated quinolones is abolished both in a ... | 1992 | 1371844 |
| construction of salmonella strains with both antigen o4 (of group b) and antigen o9 (of group d). | a salmonella live vaccine causing both o4- and o9-specific immune responses would be of use, but no reported salmonella serotype has both of these o antigens. constructed salmonella typhimurium strains with an rfb (o-antigen-specifying) gene cluster of type d in the chromosome and one of type b in an f'-rfb+ factor, and those with the reverse combination reacted strongly with both anti-o4 (and anti-o5) and anti-o9 sera and, if they carried reca, could be maintained in this state by growth condit ... | 1992 | 1372316 |
| structural and immunochemical studies of the lipopolysaccharides of salmonella strains with both antigen o4 and antigen o9. | two salmonella hybrid strains, sl5313 (salmonella typhimurium with a d.rfb+ gene cluster) and sl5396 (s. enteritidis with a b.rfb+ gene cluster), each expressing both o-antigen 4 (of serogroup b) and o-antigen 9 (of serogroup d) were studied by immunofluorescence using a mixture of o4-specific mouse monoclonal and o9-specific rabbit polyclonal antibodies. bound antibodies, detected by anti-mouse antibody labelled with fluorescein isothiocyanate and anti-rabbit antibody labelled with tetramethylr ... | 1992 | 1372317 |
| chemical purity and mutagenicity: case study of a drug in development. | during a routine ames assay of a potential antipsychotic drug candidate, the compound appeared to be a frameshift mutagen in salmonella typhimurium strains ta98 and ta1538. additional testing indicated the mutagenic activity was due to one or more contaminants incurred during synthesis. while the compound was initially shown to be greater than 98% pure by high-performance liquid chromatography, the presence of small amounts (0.01-0.1%) of a highly mutagenic impurity produced positive mutagenicit ... | 1992 | 1373215 |
| mutagenicity of the reaction products of dibenzo-p-dioxin with nitrogen oxides. | dibenzo-p-dioxin (dd) was made to react with various concentrations of nitrogen oxides in the dark. the mutagenicities of the reaction products were tested using salmonella typhimurium strains ta98, ta100, ta98nr and ta98/1,8-dnp6 in the presence or absence of a mammalian metabolic activation system (s9 mix). dd-nox (molar ratios 1:3, 1:6 and 1:18) reaction products exhibited mutagenic potency in strains ta98 and ta98/1,8-dnp6 without s9 mix. in a gas chromatography/mass spectrometry study, 2-ni ... | 1992 | 1373218 |
| effects of benzyladenine on prokaryotic and eukaryotic cells. | comparative studies of the effect of benzyladenine (ba) on the yeast saccharomyces cerevisiae, the bacterium salmonella typhimurium, the shallot allium ascalonicum and chinese hamster fibroblast cells were performed. the tested substance had no mutagenic activity on yeast, bacteria and cultured fibroblast cells. changes in mitotic activity and cell division abnormalities were observed after ba treatment in shallot root-tip cells. | 1992 | 1373222 |
| monoclonal secretory immunoglobulin a protects mice against oral challenge with the invasive pathogen salmonella typhimurium. | hybridomas producing monoclonal immunoglobulin a (iga) antibodies against salmonella typhimurium were generated by mucosal immunization of balb/c mice with attenuated strains of s. typhimurium and subsequent fusion of peyer's patch lymphoblasts with myeloma cells. to test the role of secretory iga (siga) in protection against salmonella sp., we analyzed in detail the protective capacity of a monoclonal iga, sal4, produced in polymeric as well as monomeric forms, that is directed against a carboh ... | 1992 | 1373399 |
| chromosomal changes in chinese hamster aa8 cells caused by podophyllin, a common treatment for genital warts. | podophyllin, a plant derivative of variable composition, is used widely within new zealand as a treatment for genital warts. one local source of podophyllin has been tested for ability to cause mutagenic effects in salmonella typhimurium as well as for effects on chromosomes of chinese hamster aa8 cells. although only weakly mutagenic in one strain of salmonella, podophyllin caused structural aberrations as well as changes in chromosome number in the chinese hamster cells. the range of aberratio ... | 1992 | 1373833 |
| simultaneous evaluation of genotoxicity data from different sources: a multivariate statistical approach. | a great deal of information on short-term mutagenicity assays presently exists, having been generated through individual as well as large comparative programs. the comparative programs have often examined the same tests, but with different sets of chemicals; this then gives rise to the problem of how to identify the information which is common to the different data bases, i.e., the general properties of the assays. this paper continues previous analyses of this subject, and describes a general a ... | 1992 | 1373840 |
| effects of various chemical compounds on spontaneous and hydrogen peroxide-induced reversion in strain ta104 of salmonella typhimurium. | in experiments designed to determine which active oxygen species contribute to hydrogen peroxide (hp)-induced reversion in strain ta104 of salmonella typhimurium, 1,10-phenanthroline (an iron chelator, which prevents the formation of hydroxyl radicals from hp and dna-bound iron by the fenton reaction), sodium azide (a singlet oxygen scavenger), and potassium iodide (an hydroxyl radical scavenger) inhibited hp-induced reversion. these results indicate that hydroxyl radicals generated from hp by t ... | 1992 | 1373841 |
| comparison of the mutagenicity of quinoline and all monohydroxyquinolines with a series of arene oxide, trans-dihydrodiol, diol epoxide, n-oxide and arene hydrate derivatives of quinoline in the ames/salmonella microsome test. | fourteen new quinoline derivatives were synthesised and their mutagenicity compared in the ames test using salmonella typhimurium ta100 as indicator strain with and without (aroclor-induced) s9 mix. none of the synthesised quinoline derivatives had to our knowledge been examined before in the ames test. quinoline and the monohydroxyquinolines were included as reference compounds. three of the new derivatives, i.e., quinoline 7,8-oxide, n-methyl-quinoline 5,6-oxide and trans-quinoline-5,6,7,8-dio ... | 1992 | 1373859 |
| collaborative study of mutagenicity with salmonella typhimurium ta102. | thirty compounds of various chemical classes were investigated for mutagenicity in a collaborative study (3 laboratories) using salmonella typhimurium ta102. with 5 compounds, namely hydrazine sulfate, phenylhydrazine, hydralazine, glutardialdehyde and glyoxal, mutagenicity was detected by all laboratories. formaldehyde was assessed as weakly mutagenic in only 1 of 3 laboratories. the remaining 24 agents were uniformly described as non-genotoxic in ta102. in spite of the overall good qualitative ... | 1992 | 1373863 |
| enhancement of the mutagenicity of iq and meiq by nitrite in the salmonella system. | the fried food mutagens iq, meiq, glu-p-1 and trp-p-2 were treated with nitrite at ph 3.0 for 1 h at 37 degrees c. the resulting reaction mixtures were tested for mutagenicity towards salmonella typhimurium ta97, ta98, ta100 and ta1535. glu-p-1 and trp-p-2 were readily converted to weak or non-mutagenic deaminated compounds, whereas iq and meiq were converted to extremely strong mutagenic derivatives in both the presence and the absence of rat liver s9 mix. the mutagenicity of meiq in ta98 was e ... | 1992 | 1373865 |
| cobalamin (vitamin b12) repression of the cob operon in salmonella typhimurium requires sequences within the leader and the first translated open reading frame. | expression of the cob operon in salmonella typhimurium is repressed by cobalamin (cbl). here it is shown that cbl repression is mediated by a post-transcriptional regulatory mechanism that requires sequences within the leader and the first translated open reading frame, the cbia gene. transcriptional and translational cob::lacz fusions containing various lengths of cob dna were analysed. in a translational cob::lacz fusion 407 bp of leader sequence (+69 to +476) was sufficient to confer normal r ... | 1992 | 1374146 |
| processing of a polycistronic mrna requires a 5' cis element and active translation. | we have characterized a major processed species of mrna in the his operon of salmonella typhimurium. in vivo and in vitro analyses of the his transcripts from wild-type and mutant strains using s1 nuclease protection assays, measurements of rna stability, deletion mapping, gel retardation, and in vitro translation assays demonstrate that the distal portion of the polycistronic his mrna is processed, resulting in increased stability. the processing event requires an upstream cis-acting element an ... | 1992 | 1374148 |
| electrophoretic and chemical characterization of lipopolysaccharides of vibrio parahaemolyticus. | lipopolysaccharides (lpss) isolated from three kanagawa-positive and three negative strains of vibrio parahaemolyticus were characterized by using electrophoretic, immunochemical, and chemical methods. the results of this study indicated that the lpss of all six strains of v. parahaemolyticus examined did not have an o-specific side chain. these v. parahaemolyticus lpss appeared to have molecular weights similar to that of the rough-type (ra) lps of salmonella typhimurium tv-119 and might just c ... | 1992 | 1374376 |
| cloning and nucleotide sequence of the gene (citc) encoding a citrate carrier from several salmonella serovars. | the nucleotide sequence of the citc coding for the citrate carrier in several salmonella serovars has been determined, and the amino acid sequence of the carrier protein was deduced. the predicted citrate carrier from salmonella pullorum and salmonella enteritidis consists of 446 amino acids with a molecular weight of 47,621, whereas that from salmonella dublin is the same 446 amino acids with the slightly different molecular weight of 47,591, because 1 amino acid residue was substituted. the pr ... | 1992 | 1374406 |
| integrated assessment of contaminated sediments in the lower fox river and green bay, wisconsin. | samples of sediment and biota were collected from sites in the lower fox river and southern green bay to determine existing or potential impacts of sediment-associated contaminants on different ecosystem components of this great lakes area of concern. evaluation of benthos revealed a relatively depauperate community, particularly at the lower fox river sites. sediment pore water and bulk sediments from several lower fox river sites were toxic to a number of test species including pimephales prom ... | 1992 | 1375148 |
| investigation of the mutagenic activity in salmonella typhimurium of the furochromone khellin, proposed as a therapeutic agent for skin diseases. | the photomutagenicity of the furochromone khellin was tested in ames salmonella strains using 8-methoxypsoralen (8-mop) and 4,5', 8-trimethylpsoralen (tmp) as positive controls. when khellin was assayed with strain ta1537, mutation induction was not detectable; in the same strain, an equitoxic dose (52-56% level of survival) of tmp (used at a concentration 12-fold lower than khellin and with a uva dose 83-fold lower than that used with khellin) yielded an increase in revertants/plate 3-fold abov ... | 1992 | 1375334 |
| enhanced mutagenicity of anisidine isomers in bacterial strains containing elevated n-acetyltransferase activity. | in previous studies on the mutagenicity of anisidine isomers, the ortho isomer was considered to be mutagenic towards standard ames tester strains, while the para isomer gave equivocal results. in the present study we show that both para- and ortho-anisidine isomers are mutagenic in a salmonella typhimurium tester strain containing elevated levels of n-acetyltransferase (yg1029). p-anisidine gave a positive mutagenic response using either hamster s9 or ram seminal vesicle microsomes (rsvm) as an ... | 1992 | 1375342 |
| synthetic recombinant vaccine expressing influenza haemagglutinin epitope in salmonella flagellin leads to partial protection in mice. | the influenza virus haemagglutinin epitope 91-108, which is a conserved amino acid sequence in all type a h3 strains, was expressed in salmonella flagellin, to evaluate its potential as a vaccine. for that purpose, a synthetic oligonucleotide comprising 54 bases coding for the corresponding sequence was inserted into the plasmid pls408 and transformed into escherichia coli jm101. colonies containing the recombinant plasmid were used to transform salmonella typhimurium lb5000 and were then transd ... | 1992 | 1376012 |
| effects of staphylococcal enterotoxin b on rodent mast cells. | staphylococcal enterotoxin b (seb) was tested in rodent mast cell cultures for the release of serotonin. both rat rbl-2h3 mast cells and murine peritoneal cells released serotonin after seb stimulation in culture. release of serotonin in rbl-2h3 cells depended on the concentration of seb; an appreciable release was seen at 50 micrograms/ml. the release of serotonin was not due to cell death. serotonin release could be enhanced by bradykinin but not by vasoactive intestinal peptide, substance p, ... | 1992 | 1377185 |
| chinese medicinal herbs modulate mutagenesis, dna binding and metabolism of aflatoxin b1. | oldenlandia diffusa (od) and scutellaria barbata (sb) have been used in traditional chinese medicine for treating liver, lung and rectal tumors while astragalus membranaceus (am) and ligustrum lucidum (ll) are often used as an adjunct in cancer therapy. in this study, we determined the effects of aqueous extracts of these four herbs on aflatoxin b1 (afb1)-induced mutagenesis using salmonella typhimurium ta100 as the bacterial tester strain and rat liver 9000 x g supernatant as the activation sys ... | 1992 | 1377337 |
| mutagenicity of quinolines in salmonella typhimurium ta100. a qsar study based on hydrophobicity and molecular orbital determinants. | the mutagenicity of 33 quinolines in the salmonella test using ta98 and ta100 cells has been reported. significant activity was found only with ta100 cells. quantitative structure-activity relationships (qsar) could be formulated using molecular orbital parameters or hammett constants and hydrophobic parameters for those compounds with substituents in the 6, 7 and 8 positions. the qsar points to the 2-position on the quinoline ring as being the site for activation by s9 oxidation. | 1992 | 1377345 |
| on the induction of umu gene expression in salmonella typhimurium strain ta1535/psk1002 by some nitrofurans. | several nitrofurans were found to induce umu gene expression in salmonella typhimurium ta1535/psk1002 as defined on the basis of at least a 2-fold increase of beta-galactosidase activity over the background level. beta-galactosidase activity increased with increasing concentrations of the chemical, attained a maximum at a concentration which was different for different nitrofurans used, and then gradually decreased with a further increase of the nitrofuran concentration. the umu gene expression ... | 1992 | 1377346 |
| inhibition of mutagenesis by p-aminobenzoic acid as a nitrite scavenger. | nitrite treatment enhances the direct-acting mutagenicity of various foodstuffs (e.g., chicken, bloater, the soybean flour 'kinako', and ban-ban-chi sauce) on salmonella typhimurium ta100. p-aminobenzoic acid (paba) and glutathione (gsh) reduced this mutagenicity; on the other hand, thioproline (tpro) increased it. paba seemed more effective than tpro in scavenging nitrite ion. in analysis of the reactions of paba and sodium nitrite under acidic conditions (ph 3.0), p-hydroxybenzoic acid (phba) ... | 1992 | 1377350 |
| mutagenicity of n,n'-dimethylurea and methylamine hydrochloride in the ames salmonella/microsome test: absence of mutagenic response. | methyl isocyanate (mic) in aqueous solution forms methylamine (ma) and n,n'-dimethylurea (dmu). ma in buffered system further converts into its salt form, methylamine hydrochloride (mah). therefore, mah and dmu were evaluated for their mutagenic activity in the in vitro ames salmonella/microsome mutagenicity test. the liquid preincubation protocol was followed, using tester strains ta98, ta100 and ta104 of salmonella typhimurium, in the presence of 0, 5, 15 and 30% aroclor 1254-induced rat liver ... | 1992 | 1377783 |
| molecular cloning of the rfb region of klebsiella pneumoniae serotype o1:k20: the rfb gene cluster is responsible for synthesis of the d-galactan i o polysaccharide. | previous chemical analyses identified two structurally distinct o polysaccharides in the lipopolysaccharide of klebsiella pneumoniae serotype o1:k20 (c. whitfield, j. c. richards, m. b. perry, b. r. clarke, and l. l. maclean, j. bacteriol. 173:1420-1431, 1991). the polysaccharides were designated d-galactan i and d-galactan ii; both are homopolymers of galactose. to begin investigation of the synthesis and expression of these o polysaccharides, we have cloned a 7.3-kb region of the chromosome of ... | 1992 | 1378055 |
| quantitative structure-mutagenic activity relationships of triazino indole derivatives. | the mutagenicity of 3-(4'-benzylidenamino)-5h-1,2,3-triazin[5,4-b]-indol-4-one derivatives, new compounds with considerable platelet antiaggregating activity, was assayed with the ames test using the salmonella typhimurium strains ta97, ta98, ta100 and ta102. the adaptive least-squares method (als method) was used to carry out a quantitative structure-activity relationship (qsar) analysis. three equations, based on 10 congeners, were found for strains ta97, ta98 and ta100. the results suggest th ... | 1992 | 1378175 |
| sensitivity of different bacterial assays in detecting mutagens in urine of humans exposed to polycyclic aromatic hydrocarbons. | the urine mutagenicity and excretion of 1-hydroxypyrene (1-oh pyr) in non-smoking psoriatic patients treated topically with coal-tar-based ointments were analysed in order to find the most appropriate procedure for monitoring occupational pah exposure. the bacterial mutagenicity assays used were the plate incorporation, macro-scale fluctuation and microsuspension tests, all on salmonella typhimurium strain ta98 in the presence of s9 mix and beta-glucuronidase. the sensitivities of the three assa ... | 1992 | 1378179 |
| photo-enhancement of the mutagenicity of 9-anilinoacridine derivatives related to the antitumour agent amsacrine. | the frameshift mutagenicity of the dna intercalating drug proflavine is known to be enhanced by photoirradiation of bacterial cultures. to determine whether this phenomenon was also present in acridine-derived antitumour drugs, cultures of salmonella typhimurium were exposed to the antileukaemia agent amsacrine and the experimental agent n-[2-(dimethylamino)ethyl]acridine-4-carboxamide dihydrochloride (acridine carboxamide) in the presence or absence of visible light. a small increase in mutagen ... | 1992 | 1378184 |
| identification of formate dehydrogenase-specific mrna species and nucleotide sequence of the fdhc gene of methanobacterium formicicum. | the overlapping fdha and fdhb genes of methanobacterium formicicum, which encode the alpha and beta subunits, respectively, of formate dehydrogenase, were cotranscribed as part of an approximately 4.5-kb transcript. an additional gene (fdhc) upstream of fdha was cotranscribed with fdha and fdhb. the deduced amino acid sequence suggested that fdhc has the potential to encode a hydrophobic polypeptide with a calculated molecular weight of 29,417. a hydropathy plot of the hypothetical polypeptide i ... | 1992 | 1378430 |
| mutagenic potency of heterocyclic amines towards salmonella typhimurium; possible causes of variability in the results observed. | the potent food mutagens and carcinogens 2-amino-3-methylimidazol[4,5-f]quinoline (iq), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (meiq) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (meiqx) are probably the most active bacterial mutagens so far discovered. important discrepancies were found, however, in the specific mutagenicities published for these compounds. this paper analyzes a number of experimental factors that could explain these differences: purity of the compounds, stability und ... | 1992 | 1378534 |
| the presence of genotoxic and bioactive components in indigo dyed fabrics--a possible health risk? | extracts of pure cotton and jeans fabrics were tested for mutagenicity in salmonella typhimurium strains ta98 and ta100. the vat dye indigo, technical grade as well as 98% and greater than 99.5% pure, was also tested for mutagenicity. synthetic indigo, indirubin and isatin were tested for tcdd receptor affinity in competition experiments in vitro. the mutagenicity of the extracts was associated with the cotton denim and nondyed cotton gave only marginal effects. the mutagenicity of the indigo dy ... | 1992 | 1378557 |
| comparison of acyltransferase-mediated mutagenicity and nucleic acid binding of n-acetoxy-4-acetylaminobiphenyl by hepatic and bladder microsomes from rats and dogs. | acyltransferase-mediated mutagenic and metabolic activation of n-acetoxy-4-acetylaminobiphenyl (n-oac-aabp) by hepatic tissues of rats and dogs were compared. n-oac-aabp was mutagenic in salmonella typhimurium ta98 even in the absence of exogenous enzyme(s). however, supplementation with hepatic microsomes from dogs showed a dose-dependent increase in mutagenicity of n-oac-aabp, whereas under the same conditions, rat microsomes were inactive. incubation of liver microsomes with rna showed that 4 ... | 1992 | 1379179 |
| endothelial leukocyte adhesion molecule-1 in endotoxin-induced uveitis. | expression of endothelial leukocyte adhesion molecule-1 (elam-1) on endothelial cells leads to the attachment of polymorphonuclear leukocytes. the sequential expression of elam-1 and major histocompatibility complex (mhc) class ii antigen was examined in the eyes of 59 lewis rats with endotoxin-induced uveitis (eiu) after the injection of salmonella typhimurium endotoxin. the eyes were enucleated at 2-hr intervals. hematoxylin and eosin-stained paraffin-embedded sections and immunohistochemicall ... | 1992 | 1379217 |
| in vitro and in vivo mutagenicity studies on sporidesmin, the toxin associated with facial eczema in ruminants. | sporidesmin, a fungal toxin with widespread distribution within new zealand, is thought to exert toxic effects through oxidative damage. the purified chemical was tested for its ability to cause point mutations in four strains of salmonella typhimurium (ta98, ta100, ta102 and ta1537), in the presence and absence of exogenous metabolic activation. although toxic effects were seen at concentrations exceeding 400 mu gl/plate, there were no significant increases in revertant colonies. in strain ta10 ... | 1992 | 1379325 |
| nucleotide sequences of the genes regulating o-polysaccharide antigen chain length (rol) from escherichia coli and salmonella typhimurium: protein homology and functional complementation. | in this article, we report on the nucleotide sequences of the rol genes of escherichia coli o75 and salmonella typhimurium lt2. the rol gene in e. coli was previously shown to encode a 36-kda protein that regulates size distribution of the o-antigen moiety of lipopolysaccharide. the e. coli and s. typhimurium rol gene sequences consist of 978 and 984 nucleotides, respectively. the homology between the nucleotide sequences of these two genes was found to be 68.9%. both the e. coli rol and s. typh ... | 1992 | 1379582 |
| purified prostaglandin synthase activates aromatic amines to derivatives that are mutagenic to salmonella typhimurium. | prostaglandin h synthase (phs) is widely distributed in mammalian tissues and has the ability to oxidize a variety of mutagens and carcinogens. it may therefore play a key role in the metabolic activation of xenobiotics. the present study documents that highly purified phs can be used in conjunction with 5-phenyl-4-pentenyl-1-hydroperoxide (pphp), a relatively stable and non-mutagenic hydroperoxide substrate, for the metabolic activation of aromatic amines to mutagenic derivatives that can be de ... | 1992 | 1379690 |
| bacterial motility is a colonization factor in experimental urinary tract infection. | in an experimental urinary tract infection of the mouse, colonization of the urinary bladder by isogenic strains of salmonella enterica serovar typhimurium was found to depend on the motility of the bacteria. strains were obtained by genetic recombination between a highly motile o-6,7 and a poorly motile o-4,5,12 strain. the o antigen did not interfere with the colonization, whereas motility did; flagellated and motile o-6,7 and o-4,5,12 bacteria colonized the bladder equally well. | 1992 | 1379992 |
| preferential induction of at-ta transversion, but not deletions, by chlorambucil at the hisg428 site of salmonella typhimurium ta102. | the chemotherapeutic agent chlorambucil effectively induces deletion mutations in mouse germ cells. the possibility that this chemical also effectively induces deletion mutations in bacterial dna was examined using ames salmonella tester strains. chlorambucil was mutagenic only to strains ta102 (hisg428, rfa/pkm101) and yg2975 (hisg46, rfa/pkm101) when s9 mix was absent. since strain ta102 can detect short deletions, the mutational changes of ta102 induced by this agent without s9 mix were direc ... | 1992 | 1380660 |
| mutagenicity of nitro derivatives produced by exposure of dibenzofuran to nitrogen oxides. | dibenzofuran (df) was reacted with various concentrations of nitrogen oxides (nox) under light irradiation. the mutagenicities of the reaction mixtures were tested using salmonella typhimurium strains ta98, ta100, ta98nr and ta98/1,8-dnp6 in the presence or absence of a mammalian metabolic activation system (s9 mix). df-nox (molar ratios 1:3, 1:6 and 1:18) reaction mixtures exhibited mutagenic potency in strain ta98 without s9 mix, and their direct-acting mutagenicity was reduced in strains ta98 ... | 1992 | 1380661 |
| evaluation of amitrole mutagenicity in salmonella typhimurium using prostaglandin synthase activation. | amitrole is a herbicide which has been found to induce thyroid and liver tumours in rodents, yet demonstrates limited genotoxic activity. the lack of mutagenicity of this compound in salmonella typhimurium when employing a standard liver microsomal fraction, combined with evidence of activation of amitrole by peroxidases, warranted an investigation employing this other pathway of metabolic activation. using prostaglandin h synthase as the activating system, the aromatic amine 2-aminofluorene pro ... | 1992 | 1380667 |
| a straight correlation between mutagenic activity and beta-galactosidase activity induced by monofunctional alkylating agents. | eight monofunctional alkylating agents were examined for their ability to induce mutation in salmonella typhimurium. the assay was carried out in s. typhimurium ta100 with the preincubation method. the sn1-type agents were more mutagenic than the sn2-type ones; besides, methylating agents exerted more mutagenic activity than ethylating ones. those responses in the reversion assay were quite similar to the results obtained previously with the beta-galactosidase assay in escherichia coli csh26/pmc ... | 1992 | 1380669 |
| structure-activity relationships of aromatic diamines in the ames salmonella typhimurium assay. part ii. | structure-activity relationships in the case of aromatic monoamines, diversely substituted on the ring, using the mutagenic activity in the ames test were studied in part i. this part ii is based on the same general principles but applied to phenylene diamines (ortho, para and meta) diversely substituted on the ring. | 1992 | 1381475 |
| effects of supercypermethrin, a synthetic developmental pyrethroid, on four biological test systems. | the genotoxic potential of the insecticide supercypermethrin, a second-generation pyrethroid, was studied on four different test systems. it was non-mutagenic to salmonella typhimurium strains ta1535, ta100, ta1538, ta98 and ta97 in the presence and absence of s9 mixture. it induced gene conversion at the tryptophan locus and induced point mutations at the isoleucine locus in saccharomyces cerevisiae cells. a slight increase in the frequency of aberrant anaphases and telophases in root tips of h ... | 1992 | 1381478 |
| mechanism of mutagenicity by 5-hydroperoxymethyl-2'-deoxyuridine, an intermediate product of ionizing radiation, in bacteria. hpmdu bacterial mutagenicity and oxidation of dna bases. | the specific objective was to find what processes are responsible for the mutagenicity of 5-hydroperoxymethyl-2'-deoxyuridine (hpmdu), which is a product of ionizing radiation, and what role transition metal ions play in those processes. we found that hpmdu is a more potent mutagen than its decomposition products 5-hydroxymethyl-2'-deoxyuridine (hmdu) and 5-formyl-2'-deoxyuridine (fdu) in the salmonella typhimurium strains tested, with the ta100 strain being the most sensitive. hmdu exerted inte ... | 1992 | 1381492 |
| hypothesis for vaccine development: protective immunity to enteric diseases caused by nontyphoidal salmonellae and shigellae may be conferred by serum igg antibodies to the o-specific polysaccharide of their lipopolysaccharides. | immunoprophylaxis for bacterial enteric diseases is hindered because the protective immune mechanism(s) against nontyphoidal salmonellae or shigellae in humans are not established. on the basis of the similarities between the clinical signs, epidemiology, pathogenesis, and pathology of as well as protective immunity to salmonellae and shigellae, we propose that serum igg antibodies to the o-specific polysaccharide (o-sp) of their lipopolysaccharides (lpss) will confer protective immunity to thes ... | 1992 | 1381621 |
| structure-mutagenicity relationships in a series of indolo[3,2-c]quinoline-1,4-diones that have shown cytotoxic properties on leukemia cells. | a series of seven 6-methylindolo[3,2-c]quinoline-1,4-diones substituted either in the 2 position or in 3 position by various groups were examined for their ability to induce mutation in the ames test at several concentrations in four strains of salmonella typhimurium (ta97, ta98, ta100, and ta102). first, relationships were established between their mutagenic activities and either the nature or the position of the substituent on the quinonic nucleus. compounds substituted in the 2 position were ... | 1992 | 1382223 |
| mutagenic activities of azido analogues of amsacrine and other 9-anilinoacridines in salmonella typhimurium and their enhancement by photoirradiation. | analogues of amsacrine and other 9-anilinoacridines, bearing azide groups at various positions, were tested for their mutagenic activity in five strains of salmonella typhimurium, both before and after photoirradiation. azido substitution at the 2- or 3-position of the acridine or the 1'-position of the aniline led to compounds which were active frameshift mutagens, as detected in strain ta1537. photoirradiation enhanced both the mutagenicity and the cytotoxicity of the azido compounds. analogue ... | 1992 | 1382224 |
| studies on antigen specifity of immunoreactive arabinogalactan proteins extracted from baptisia tinctoria and echinacea purpurea. | in a series of experiments the cross-reactivity of antibodies raised against arabinogalactan proteins from baptisia tinctoria and echinacea purpurea was studied in order to prove the antigen specificity of the extracted glycoproteins/polysaccharides. using the antigen-antibody reaction in a competitive elisa it was evident that antibodies against glycoproteins from baptisia tinctoria were specific because none of the other antigens like those from echinacea purpurea, thuja occidentalis, arabinog ... | 1992 | 1382301 |
| the role of o-antigen polysaccharide in the activation of neutrophils by lipopolysaccharides of salmonella species. | activation of neutrophils by lipid a, o-antigen polysaccharides (ps) and smooth lipopolysaccharides (lps) isolated from salmonella choleraesuis (o-6,7) and salmonella typhimurium (o-4,5,12) was investigated. the methods used were assays for lysozyme release and for nitroblue tetrazolium (nbt) reduction which measures the level of oxidative metabolism of neutrophils. lps from both species stimulated neutrophils to the same extent in the presence of autologous plasma. in the absence of plasma only ... | 1992 | 1382904 |
| protection of mice against salmonella typhimurium with an o-specific polysaccharide-protein conjugate vaccine. | serious infections with salmonellae remain a threat in many human populations. despite extensive study of salmonella infections in animals and clinical experience with killed cellular vaccines, there are no vaccines against serotypes other than salmonella typhi licensed for human use. serum antibodies to the o-specific polysaccharide (o-sp) of salmonellae protect mice against invasive infection. in order to render it immunogenic, we have conjugated the o-sp of salmonella typhimurium to carrier p ... | 1992 | 1383154 |
| enhancement of the mutagenicity of polyphenols by chlorination and nitrosation in salmonella typhimurium. | the hydrolytic products of lignins, humic acids and industrial waste including hydroquinone, catechol, resorcinol, pyrogallol and 1,2,4-benzenetriol are widely distributed in water sources. these polyphenols can interact with chlorine or nitrite to yield new derivatives. generally, these new products possess more mutagenic potential than their original compounds. furthermore, the mutagenicity of these polyphenols and their derivatives can be dramatically reduced by rodent liver microsomal enzyme ... | 1992 | 1383704 |
| mutagenic activation of aflatoxin b1 by pulmonary, renal, and hepatic cytochrome p450s from rats. | the genotoxic and mutagenic activation of aflatoxin b1 (afb1) by hepatic, renal, and pulmonary microsomes and purified cytochrome p450s was investigated in salmonella typhimurium ta1535/psk1002 cells in which an umu response shows dna damage. the activity of the hepatic microsomes was greatest. pulmonary microsomes had moderate activity and renal microsomes had low activity. p450 2c11, 2b1, 3a2, 4a2, 4b1, k-2, and k-4 were assayed in a reconstituted system with dilauroylphosphatidylcholine (dlpc ... | 1992 | 1383706 |
| effect of vitamin a dietary intake on in vitro and in vivo activation of aflatoxin b1. | the mechanism by which vitamin a prevents or delays in chemical carcinogenesis remains unclear. in the present study, we assess the suggestive role of vitamin a in the initiation phase of carcinogenesis. we have conducted a dose-effect relationship between vitamin a dietary intake and aflatoxin b1 (afb1) genotoxicity measured both in vitro and in vivo. thus afb1-induced mutagenesis in salmonella typhimurium ta98 was investigated and compared to afb1-induced single-strand breaks (ssbs) in dna of ... | 1992 | 1383711 |
| inhibition of the metabolism of mutagens occurring in food by arachidonic acid. | hepatic microsomal fractions (microsomes) were prepared from male sprague-dawley rats. the effect of arachidonic acid on the conversion of the heterocyclic aromatic amine 2-amino-3-methylimidazo[4,5-f]quinoline (iq) to its genotoxic metabolites was investigated using a modified bacterial mutation assay (indicator: salmonella typhimurium ta98). arachidonic acid inhibited the mutagenicity of iq without effect on the uptake of the active metabolites and/or on the dna-repair processes within the bac ... | 1992 | 1383712 |
| use of a newly developed tester strain salmonella typhimurium nm2009 for the study of metabolic activation of carcinogenic aromatic amines by rat liver microsomal cytochrome p-450 enzymes. | using an o-acetyltransferase-overexpressing strain salmonella typhimurium nm2009 we measured the activities for metabolic activation of several carcinogenic arylamines to genotoxic products by rat liver microsomal cytochrome p-450 enzymes, and compared them with the activities obtained in the original tester strain salmonella typhimurium ta1535/psk1002 or the o-acetyltransferase-defective strain salmonella typhimurium nm2000. since all of the tester strains had introduced the umuc'-'lacz gene, w ... | 1992 | 1383750 |
| a sensitive umu test system for the detection of mutagenic nitroarenes in salmonella typhimurium nm1011 having a high nitroreductase activity. | a sensitive umu test system for the detection of mutagenic nitroarenes has been developed using a new tester strain salmonella typhimurium nm1011 having a high nitroreductase activity. the new strain was constructed by subcloning the bacterial nitroreductase gene into a plasmid pacyc184 and introducing the plasmid into the original strain s. typhimurium ta1535/psk1002 harboring a fusion gene umuc'-'lacz (psk1002). thus, the tester strain enabled us to monitor the genotoxic activities of various ... | 1992 | 1383753 |
| the lipid peroxidation product 4-hydroxynonenal is a potent inducer of the sos response. | an important aspect of bacterial mutagenesis by several difunctional carbonyl compounds appears to be the induction of the sos system. we tested the ability of a series of carbonyl compounds to induce expression of the sos-regulated umu operon in salmonella typhimurium ta1535/psk1002. sos-inducing potencies varied widely among the carbonyl compounds tested. 4-hydroxynonenal, a product of lipid peroxidation, was the most potent sos-inducer, with maximal induction observed at concentrations of 0.1 ... | 1992 | 1383804 |
| role of escherichia coli k-12 rfa genes and the rfp gene of shigella dysenteriae 1 in generation of lipopolysaccharide core heterogeneity and attachment of o antigen. | the rfp gene of shigella dysenteriae 1 and the rfa genes of escherichia coli k-12 and salmonella typhimurium lt2 have been studied to determine their relationship to lipopolysaccharide (lps) core heterogeneity and their role in the attachment of o antigen to lps. it has been inferred from the nucleotide sequence that the rfp gene encodes a protein of 41,864 da which has a structure similar to that of rfag protein. expression of this gene in e. coli k-12 results in the loss of one of the three ba ... | 1992 | 1385388 |
| role of the metr regulatory system in vitamin b12-mediated repression of the salmonella typhimurium mete gene. | the vitamin b12 (b12)-mediated repression of the mete gene in escherichia coli and salmonella typhimurium requires the b12-dependent transmethylase, the meth gene product. it has been proposed that the meth-b12 holoenzyme complex is involved directly in the repression mechanism. using escherichia coli strains lysogenized with a lambda phage carrying a mete-lacz gene fusion, we examined b12-mediated repression of the mete-lacz gene fusion. although b12 supplementation results in a 10-fold repress ... | 1992 | 1385596 |
| characterization of the transcription activator protein c1 of bacteriophage p22. | we cloned, expressed, and purified the positive regulatory protein c1 of the temperate phage p22 of salmonella typhimurium. the purified protein was characterized as to its amino acid composition, protein sequence, molecular weight, and antigenicity. p22 c1 was shown to be a tetrameric protein composed of four identical subunits with m(r) = 10,000. moreover, we identified and characterized two p22 c1-dependent phage promoters, p(re) and pa23, whose function was completely dependent on c1 both in ... | 1992 | 1385814 |
| antimutagenic effects of polyphenolic compounds. | smokers expose themselves to potent carcinogens daily. one of them is the nicotine-derived nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk). since estimates are that humans consume 1 g of phenolic compounds/day, we investigated the inhibitory effects of five structurally related polyphenolic compounds on the mutagenicity of nnk in salmonella typhimurium ta1535. nnk at a concentration of 80 mm was activated by hamster liver microsomes. the antimutagenic efficacies were dose-relate ... | 1992 | 1394114 |
| the mutagenic constituents of rubia tinctorum. | twenty compounds were isolated from the roots of rubia tinctorum which are used as a commercial source of madder color. among these compounds, mollugin (1), 1-hydroxy-2-methylanthraquinone (2), 2-ethoxymethylanthraquinone(11), rubiadin (13), 1,3-dihydroxyanthraqunone (14), 7-hydroxy-2-methylanthraquinone (16), lucidin (17), 1-methoxymethylanthraquinone (18) and lucidin-3-o-primeveroside (19) showed mutagenicity with salmonella typhimurium ta 100 and/or ta 98. since the mutagenic compounds isolat ... | 1992 | 1394669 |
| decomposition of linear dodecylbenzenesulfonate by simultaneous treatment with ozone and ultraviolet irradiation: rapid disappearance of formed mutagens. | the decomposition products and mutagenic activity in salmonella typhimurium strains ta98, ta100 and ta104 in the presence and absence of s9 mix of linear dodecylbenzenesulfonate (dbs) in aqueous solution after ozone treatment alone or simultaneous treatment with ozone and ultraviolet (uv) irradiation (ozone/uv treatment) were investigated. the decomposed dbs solutions after these treatments for 4 h were mutagenic for strains ta98, ta100 and ta104 both with and without s9 mix, but this mutagenici ... | 1992 | 1394680 |
| [blockage of glyrrhiza uralensis and chelidonium majus in mnng induced cancer and mutagenesis]. | glyrrhiza uralensis (gu) and chelidonium majus (cm) are two kinds of chinese herbal medicine. gu and cm not only exert much stronger effects in blocking mutagenesis due to strains of salmonella typhimurium (ta 97, ta 98, ta 100, ta 102), but also have different degrees of obstructing mutagenesis induced by furapromidum (f30066), zhengdingmycin hydrochloride (dm), n-methyl-n1-nitro-n-nitrosoguanidine (mnng) and methyl-methanesulfonate (mms). the blockage effect of gu and cm obviously depends on t ... | 1992 | 1395959 |
| evaluation of the mutagenicity of an n-nitroso contaminant of the sunscreen padimate o: n-nitroso-n-methyl-p-aminobenzoic acid, 2-ethylhexyl ester (npabao). | the nitrosamine contaminant, n-nitroso-n-methyl-p-aminobenzoic acid, 2-ethylhexyl ester (npabao), of the major sunscreen ingredient padimate o (4-n,n'-dimethylamino-benzoic acid, 2-ethylhexyl ester) was synthesized and tested for mutagenicity in the salmonella typhimurium and mouse lymphoma l5178y tk +/- assays. in contrast to the previously reported positive responses in s. typhimurium tester strains ta100 and ta1535 [loeppky et al., 1991], there were no increases in the number of revertants wi ... | 1992 | 1396609 |
| the role of glutathione in the bacterial mutagenicity of vapour phase dichloromethane. | dichloromethane (dcm) vapour by inhalation is carcinogenic to rodents and is an in vivo rodent cell clastogen and a bacterial mutagen. it has been suggested that the bacterial mutagenicity of dcm is mediated by glutathione (gsh) conjugation. the involvement of endogenous and exogenous gsh in the conversion of dcm to a bacterial mutagen has been studied in a vapour phase protocol using wild-type and gsh-deficient (ng54; gsh) salmonella typhimurium ta100 strains in the presence and absence of vari ... | 1992 | 1396612 |
| n-nitrosamine and mutagenicity formation in chinese salted fish after digestion. | salted and dried fish (nemipterus virgatus), acquired from hong kong, was treated with 0.43-110 mm nitrite during in vitro digestion using gastric enzymes and the volatile n-nitrosamine content and mutagenicity on salmonella typhimurium ta100 assayed without concentration. n-nitrosodimethylamine (ndma; the only nitrosamine detected) formation was second order in nitrite concentration. when 10 g of fish was treated with 6.96 mm nitrite, 394 nm ndma was formed. thiocyanate was catalytic for ndma f ... | 1992 | 1397390 |
| efflux of choline and glycine betaine from osmoregulating cells of escherichia coli. | we present evidence that glycine betaine (betaine) which was synthesized from choline was excreted and reaccumulated in osmoregulating cells of escherichia coli. choline which was accumulated in bet mutants defective in betaine synthesis was shown to be excreted in response to betaine uptake. our data suggest that e. coli has efflux systems for betaine and choline which are independent of the uptake systems for these metabolites. the prou system of e. coli, but not that of salmonella typhimurium ... | 1992 | 1398030 |
| isolation and complete sequence of the purl gene encoding fgam synthase ii in lactobacillus casei. | the purl gene from lactobacillus casei, encoding phosphoribosylformylglycinamidine synthase ii involved in the de novo synthesis of purines, was cloned and sequenced. the putative purl product of 741 amino acids (m(r) of 79,575) shows 25% and 53% identity to the homologous enzymes from escherichia coli and bacillus subtilis, respectively. in addition, partial sequences of two other pur genes (purq and purf) and a possible third gene (purc) were obtained. all these genes are organized in an opero ... | 1992 | 1398079 |
| comparison of the complete sequence of the str operon in salmonella typhimurium and escherichia coli. | the nucleotide (nt) sequences of the str operon in escherichia coli k-12 and salmonella typhimurium lt2 were completed and compared at the nt and amino acid (aa) level. the order of conservation at the nt and aa level is rpsl greater than tufa greater than rpsg greater than f usa. a striking difference is that the rpsg-encoded ribosomal protein, s7, in e. coli k-12 is 23 aa longer than in s. typhimurium. the very low (0.18) codon adaptation index of this part of the e. coli k-12-encoding gene an ... | 1992 | 1398129 |
| citrobacter sepsis in infants. | a study of blood cultures from 320 cases of neonatal sepsis showed 136 (42.5%) to be positive for bacterial growth; of these 82 (60.29%) isolates being gram negative bacilli. citrobacter was the commonest gram negative bacilli isolated. other commonly isolated gram negative organisms were pseudomonas, klebsiella, salmonella typhimurium, acinetobacter and escherichia coli. antibiotics susceptibility pattern revealed the isolates to be resistant to commonly used antibiotics. | 1992 | 1398863 |
| characterization of a salmonella typhimurium aro vaccine strain expressing the p.69 antigen of bordetella pertussis. | the p.69 bordetella pertussis protective antigen was expressed by use of the trc promoter from the chromosome of a salmonella typhimurium aro vaccine strain, brd509, by integrating the prn gene, encoding the 93-kda precursor of this protein, into the aroc locus. p.69 was detected on the cell surface of the s. typhimurium strain (brd640) by agglutination and immunoelectron microscopy. balb/c mice immunized orally or intravenously with brd640 showed a significant level of protection against an aer ... | 1992 | 1398911 |
| specific lung mucosal and systemic immune responses after oral immunization of mice with salmonella typhimurium aroa, salmonella typhi ty21a, and invasive escherichia coli expressing recombinant pertussis toxin s1 subunit. | pertussis toxin (pt) is considered an essential protective component for incorporation into new generation vaccines against bordetella pertussis, the causative agent of whooping cough. traditionally, antipertussis vaccination has employed an intramuscular route. an alternative to this approach is to stimulate mucosal and systemic immune responses by oral immunization with live vaccine carrier strains of salmonella spp. or escherichia coli. recombinant s1 subunit of pertussis toxin was expressed ... | 1992 | 1398937 |
| lipid a in helicobacter pylori. | free lipid a of helicobacter pylori was characterized with regard to chemical composition, reactivity with anti-lipid a antibodies, and activity in a limulus lysate assay. the predominant fatty acids of h. pylori lipid a were 3-oh-18:0, 18:0, 3-oh-16:0, 16:0, and 14:0. hexosamine was present in amounts similar to those in campylobacter jejuni or salmonella typhimurium lipid a. the lipopolysaccharide of h. pylori contained 2-keto-3-deoxyoctonic acid, a common constituent of enterobacterial and c. ... | 1992 | 1398948 |
| rapid generation of specific protective immunity to francisella tularensis. | mice inoculated either subcutaneously (s.c.) or intradermally (i.d.) with a sublethal dose of francisella tularensis lvs are immune to a lethal intraperitoneal (i.p.) or intravenous (i.v.) challenge of lvs. here, we show that this immunity developed quite rapidly: mice given a sublethal dose of live lvs s.c. or i.d. (but not i.v.) withstood lethal i.p., i.v., or i.d. challenge as early as 2 days after the initial inoculation, despite the presence of bacterial burdens already in tissues. the magn ... | 1992 | 1398969 |
| lactoferrin release and interleukin-1, interleukin-6, and tumor necrosis factor production by human polymorphonuclear cells stimulated by various lipopolysaccharides: relationship to growth inhibition of candida albicans. | lipopolysaccharides (lpss) from escherichia coli, serratia marcescens, and salmonella typhimurium, at doses from 1 to 100 ng/ml, strongly enhanced growth inhibition of candida albicans by human polymorphonuclear leukocytes (pmn) in vitro. flow cytometry analysis demonstrated that lps markedly augmented phagocytosis of candida cells by increasing the number of yeasts ingested per neutrophil as well as the number of neutrophils capable of ingesting fungal cells. lps activation caused augmented rel ... | 1992 | 1398974 |
| escherichia coli produces a cytoplasmic alpha-amylase, amya. | in the gap between two closely linked flagellar gene clusters on the escherichia coli and salmonella typhimurium chromosomes (at about 42 to 43 min on the e. coli map), we found an open reading frame whose sequence suggested that it encoded an alpha-amylase; the deduced amino acid sequences in the two species were 87% identical. the strongest similarities to other alpha-amylases were to the excreted liquefying alpha-amylases of bacilli, with > 40% amino acid identity; the n-terminal sequence of ... | 1992 | 1400215 |
| roles of salmonella typhimurium umudc and samab in uv mutagenesis and uv sensitivity. | expression of the umudc operon is required for uv mutagenesis and most chemical mutagenesis in escherichia coli. the closely related species salmonella typhimurium has two sets of umudc-like operons; the samab operon is located in a 60-mda cryptic plasmid, while the s. typhimurium umudc (umudcst) operon resides in a chromosome. the roles of these two umudc-like operons in uv mutagenesis and uv sensitivity of s. typhimurium were investigated. a pbr322-derived plasmid carrying the samab operon mor ... | 1992 | 1400244 |
| dna replication defect in salmonella typhimurium mutants lacking the editing (epsilon) subunit of dna polymerase iii. | in salmonella typhimurium, dnaq null mutants (encoding the epsilon editing subunit of dna polymerase iii [pol iii]) exhibit a severe growth defect when the genetic background is otherwise wild type. suppression of the growth defect requires both a mutation affecting the alpha (polymerase) subunit of dna polymerase iii and adequate levels of dna polymerase i. in the present paper, we report on studies that clarify the nature of the physiological defect imposed by the loss of epsilon and the mecha ... | 1992 | 1400246 |
| purification and characterization of the periplasmic lysine-, arginine-, ornithine-binding protein (lao) from salmonella typhimurium. | the lysine-, arginine-, ornithine-binding protein (lao) from salmonella typhimurium has been purified to homogeneity and characterized. the dissociation constants (kd) were determined by equilibrium dialysis assay to be 14, 15, and 29 nm for l-arginine, l-lysine, and l-ornithine respectively. l-histidine was found to be a relatively good ligand (kd, 500 nm). methods have been developed for the separation of liganded from unliganded lao, for the estimation of bound ligand, and for unliganding lao ... | 1992 | 1400387 |
| cytokine expression in vivo during murine listeriosis. infection with live, virulent bacteria is required for monokine and lymphokine messenger rna accumulation in the spleen. | to examine the regulation of cytokine synthesis during murine listeriosis, we have monitored ifn-gamma, tnf-alpha, and il-1 beta mrna levels in the spleens of c57b1/6 mice after the i.v. infusion of virulent and nonvirulent preparations of listeria monocytogenes (lm). messenger rna coding for tnf, il-1, or ifn did not become detectable until approximately 12 to 15 h after the infusion of virulent lm. levels of each cytokine mrna then increased synchronously reaching peak or near peak levels arou ... | 1992 | 1401929 |
| m ring, s ring and proximal rod of the flagellar basal body of salmonella typhimurium are composed of subunits of a single protein, flif. | the flagellar basal body, a major part of the flagellar motor, consists of a rod and four rings. when the flif gene of salmonella typhimurium, which was previously shown to code for the component protein of the m ring, was cloned and overexpressed in escherichia coli, the flif subunits formed ring structures in the cytoplasmic membrane. electron microscopic observation of the purified ring structures revealed that each was composed of two adjacent rings and a short appendage extending from the c ... | 1992 | 1404383 |
| expression and mutational analysis of the nucleoid-associated protein h-ns of salmonella typhimurium. | the h-ns (h1) protein is a major component of bacterial chromatin. mutations in the hns (osmz) gene encoding h-ns are highly pleiotropic, affecting the expression of many unrelated genes in an allele-specific manner. h-ns expression was found not to vary with growth phase or growth medium osmolarity. additionally, 10 independent hns mutations were isolated and characterized. five of these mutations were the result of an is10 insertion, each generating a truncated polypeptide. the other five muta ... | 1992 | 1406272 |
| the dna supercoiling-sensitive expression of the salmonella typhimurium his operon requires the his attenuator and is modulated by anaerobiosis and by osmolarity. | bacterial cells possess a subset of genes whose expression correlates with changes in dna supercoiling brought about by anaerobic growth and by growth at high osmolarity. it has been shown previously that expression of the histidine biosynthetic operon of salmonella typhimurium is derepressed by relaxation of supercoiled dna. here, we confirm that a his::mudj operon fusion in s. typhimurium can be induced by treatment with the dna gyrase inhibitor novobiocin in a dose-dependent manner, and show ... | 1992 | 1406284 |
| molecular cloning and nucleotide sequencing of a novel aminoglycoside 6'-n-acetyltransferase gene from an r-plasmid of salmonella typhimurium s24 isolated in taiwan. | a conjugative aminoglycoside resistance plasmid pst2 has been isolated from escherichia coli k-12 14r525, which was mated with a clinical isolate of salmonella typhimurium s24. a novel resistance gene of aminoglycoside 6'-n-acetyltransferase[aac(6')] was cloned from plasmid pst2 on a 1,393 kilobase (kb) of sphi-sali fragment into vector pacyc184 and puc18. this novel aac(6') gene in plasmid pst2 acetylated kanamycin, amikacin, dibekacin, tobramycin, gentamicin, netilmicin, and sisomicin. the com ... | 1992 | 1406363 |
| bactericidal activities of rat defensins and synthetic rabbit defensins on staphylococci, klebsiella pneumoniae (chedid, 277, and 8n3), pseudomonas aeruginosa (mucoid and nonmucoid strains), salmonella typhimurium (ra, rc, rd, and re of lps mutants) and escherichia coli. | rat defensins were purified and tested for in vitro bactericidal assay against gram-positive and gram-negative bacteria. staphylococcus aureus (209p, cowan i, smith diffuse and smith compact) were resistant to defensins, whereas staphylococcus epidermidis, staphylococcus saprophyticus, micrococcus lysodeikticus and bacillus subtilis were less sensitive. gram-negative bacteria, such as pseudomonas aeruginosa (mucoid and k) and klebsiella pneumoniae (chedid, 277, and 8n3 which were heavily capsula ... | 1992 | 1406365 |
| fish oil consumption influences mortality rates of mice challenged with salmonella typhimurium. | a recent report has shown that dietary fish oil consumption increases mortality in mice challenged with salmonella typhimurium. the mechanism of this effect is uncertain, however. | 1992 | 1407748 |
| retino-choroidal changes in endotoxin-induced uveitis in the rat. | a single injection of 100 micrograms of lipopolysaccharide from salmonella typhimurium in the foot pads of lewis rats induced acute inflammation of the eye. clinically, the disease started as early as 0.5 h and peaked 18 h after the inoculation. the aqueous protein concentration was increased after the inoculation. histopathologically, cellular infiltrates and proteinaceous exudates were observed in the anterior segment (anterior chamber, iris and ciliary body). in addition to those changes desc ... | 1992 | 1407958 |
| sequence comparison of new prokaryotic and mitochondrial members of the polypeptide chain release factor family predicts a five-domain model for release factor structure. | we have recently reported the cloning and sequencing of the gene for the mitochondrial release factor mrf-1. mrf-1 displays high sequence similarity to the bacterial release factors rf-1 and rf-2. a database search for proteins resembling these three factors revealed high similarities to two amino acid sequences deduced from unassigned genomic reading frames in escherichia coli and bacillus subtilis. the amino acid sequence derived from the bacillus reading frame is 47% identical to e.coli and s ... | 1992 | 1408743 |
| fermentation of [14c]lactose in broiler chicks by cecal anaerobes. | volatile fatty acids and lactic acid were products of [14c]lactose metabolism in 10-day-old broiler chicks. the [14c]lactose and unlabeled lactose were given to chicks in combination with cultures of cecal anaerobes (direct fed microbials) from adult broiler chickens. aliquots of these cecal anaerobes had been used previously to reduce salmonella typhimurium colonization in broiler chicks. in the current study, chicks were treated with anaerobes and anaerobes plus lactose on the day of hatch. ch ... | 1992 | 1409230 |
| roles of selection and recombination in the evolution of type i restriction-modification systems in enterobacteria. | restriction-modification systems can protect bacteria against viral infection. sequences of the hsdm gene, encoding one of the three subunits of type i restriction-modification systems, have been determined for four strains of enterobacteria. comparison with the known sequences of ecok and ecor124 indicates that all are homologous, though they fall into three families (exemplified by ecok, ecoa, and ecor124), the first two of which are apparently allelic. the extent of amino acid sequence identi ... | 1992 | 1409708 |
| generation of mutagenicity by ozonation of humic substances' components. | components of humic substances, such as vanillin, syringaldehyde, vanillic acid and di-n-butylphtalate, were ozonated and subjected to the mutagenicity assay using salmonella typhimurium ta 98 and 100 with and without s9 mix. the strong mutagenic activity was found on all components except di-n-butylphtalate by strain ta 100 with and without s9 mix. substances with strong mutagenic activity in ozonated vanillin were water-soluble and were slightly extracted with benzene, dichloromethane and ethy ... | 1992 | 1411491 |
| mutagenicity of nitroxyl compounds: structure-activity relationships. | three piperidinoxyl radicals were found to be directly mutagenic in salmonella typhimurium ta 100, one pyrrolidinoxyl compound had weaker activity, and two other pyrrolidinoxyl derivatives did not produce an increase of the spontaneous revertants. the tester strain ta 100 was selected in preliminary tests for its higher sensitivity compared to ta 98 and ta 102. the mutagenic activity of the three active compounds was abolished by partial reduction with ascorbic acid, suggesting that the mutageni ... | 1992 | 1412521 |
| pentamidine isethionate is negative in tests for microbial mutagenicity and chromosomal breakage in vitro. | pentamidine isethionate, a drug used for the treatment of pneumocystis carinii pneumonia in aids patients, was assayed for mutagenicity in five strains of salmonella typhimurium and for clastogenicity and mutagen-induced chromosomal breakage in five human lymphoblastoid cell lines. the mutagenicity assay employed both repair-deficient and repair-positive strains without and with the addition of rat liver s-9. there was no indication of a mutagenic response in any of the strains of salmonella. ch ... | 1992 | 1412524 |
| survey of clinical psittacine bird sera for salmonella typhimurium agglutinins. | of 2407 serum samples from various kinds of psittacine birds submitted for chlamydia serology, 2343 (97.4%) were negative, 25 (1.0%) were equivocal, and 39 (1.6%) were positive for salmonella typhimurium agglutinins. in additional serum samples from two groups of african gray parrots, the prevalence of agglutinins was 0.0% (0/38) in the timneh variety and 24.0% (6/25) in the congo variety. in sera from one macaw, one cockatoo, and one amazon parrot, which were negative for chlamydial antibody ac ... | 1992 | 1417620 |
| mechanism of the protective immunity against murine typhoid: persistence of salmonella l forms in the liver after immunization with live-cell vaccines. | live-cell vaccines of salmonella typhimurium, either a sub-lethal dose of a wild-type (strain lt2) or a high dose of its two-heptose rd1 mutant (strain sl1004), induced acquired resistance to murine typhoid, which remained 180 days after immunization. growth of s. typhimurium as a bacillary form ceased between days 30 and 60 of immunization, but l forms of this bacterium colonized the liver (the mean number of l forms in the liver: 600 l-forming units) even at 180 days post-immunization. in cont ... | 1992 | 1419117 |