Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| recombinant salmonella typhimurium strains that invade nonphagocytic cells are resistant to recognition by antigen-specific cytotoxic t lymphocytes. | to address the question of whether salmonella-infected nonphagocytic cells could serve as target cells for recognition by antigen-specific, major histocompatibility complex class i-restricted cytotoxic t lymphocytes (ctl), four recombinant salmonella typhimurium constructs that expressed full-length, or fragments of, influenza a virus nucleoprotein (np) were made. the bacteria were shown to infect chinese hamster ovary (cho) cells. appropriate major histocompatibility complex restriction molecul ... | 1992 | 1500187 |
| phosphatidylserine found in intestinal mucus serves as a sole source of carbon and nitrogen for salmonellae and escherichia coli. | salmonella choleraesuis (a pig pathogen), salmonella typhimurium (a virulent strain in mice), and three strains of escherichia coli (including a human enterohemorrhagic strain, a human urinary tract isolate, and a human fecal isolate) grew as well in vitro utilizing the lipids derived from mouse cecal mucus as the sole source of carbon and nitrogen as they did in mouse crude cecal mucus. further analysis of the total lipid extracts of mucus dialysates showed that the acidic lipid fraction suppor ... | 1992 | 1500206 |
| enteric defensins: antibiotic peptide components of intestinal host defense. | five intestinal defensins, termed cryptdins 1-5, have been purified from mouse small bowel, sequenced, and localized to the epithelium by immunohistochemistry. although identified as members of the defensin peptide family by peptide sequencing, enteric defensins are novel in that four cryptdins have amino termini which are three to six residues longer than those of leukocyte-derived defensins. a fifth cryptdin is the first defensin to diverge from the previously invariant spacing of cysteines in ... | 1992 | 1500431 |
| antigenic homology of endotoxin with a coliform mastitis vaccine strain, escherichia coli o111:b4 (j5). | this study examined recognition of heterologous gram-negative endotoxin by antibodies recognizing common lipopolysaccharide core antigens. gram-negative endotoxins from 11 heterologous bacterial strains were tested for recognition by antibodies against common lipopolysaccharide core antigens. serum was harvested from a calf immunized with the rc mutant, escherichia coli o111:b4 (j5), and affinity purified against endotoxin derived from an ra mutant, salmonella typhimurium, producing an antibody ... | 1992 | 1500577 |
| salmonella typhimurium bacteremia: association with the virulence plasmid. | virulence plasmids, which are found in a small number of salmonella serotypes, greatly enhance the extraintestinal growth of salmonellae and lower the ld50 by 2-5 logs in experimental murine infections. to determine if virulence plasmids are important in the pathogenesis of salmonella bacteremia in humans, blood and fecal isolates of salmonella typhimurium from california were examined for the presence of a virulence plasmid. colony blots were done using a labeled probe made from the highly cons ... | 1992 | 1500749 |
| interaction of protein and zinc malnutrition with the murine response to infection. | malnutrition increases the host's susceptibility to infection. however, the mechanisms are not well understood. this study examined the interaction of protein and zinc underfeeding in mice before challenge with an intracellular pathogen, salmonella typhimurium. c3h/hen mice (n = 68) were weighted and placed on one of four diets: 20% ovalbumin with adequate zinc (20% nl), 20% ovalbumin without zinc (20% lo), 1% ovalbumin with zinc (1% nl), and 1% ovalbumin without zinc (1% lo). at the end of 6 we ... | 1992 | 1501352 |
| serum tnf alpha inhibitor in mouse typhoid. | administration of anti-tnf alpha antiserum enhanced a sublethal infection with salmonellae of moderate virulence (salmonella typhimurium m525) in innately susceptible (ity(s)) balb/c mice, indicating that tnf alpha is important in the early response which suppresses bacterial growth in the reticuloendothelial system (res). however, only transient low levels of tnf alpha were detectable on day 3 in sera from some, but not all, sublethally infected mice. conversely, on day 4 of the same infection, ... | 1992 | 1501573 |
| occurrence of salmonella in swine in the latium region (central italy) from 1980 to 1989: a retrospective study. | an extensive survey was carried out on 849 biological samples (dead animals, organs and viscera, faeces, and rectal swabs) from pigs in the latium region (central italy) throughout the years 1980-1989. in total, 46 of the samples (5.4%) were found to be bacteriologically positive for salmonellae. among dead animals, typical gross lesions were observed in 6 clinically infected animals. as far as serotypes are concerned, 11 different ones were isolated, with a predominance of salmonella typhimuriu ... | 1992 | 1502777 |
| effects of different inducers of cytochrome p450 on the mutagenesis of the tobacco-specific nitrosamine 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone (nnk) in salmonella typhimurium ta1535. | the effects of six inducers of isoenzymes of cytochrome p450 on the mutagenicity of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk) in salmonella typhimurium strain ta1535 by hamster liver s9 and microsomes were investigated. comparisons of the effects of dimethylsulfoxide (dmso) as solvent for nnk were also made. the inducing agents were aroclor 1254 (aroc), 3-methylcholanthrene (mc), phenobarbital (pb), dexamethasone (dxm), ethanol (etoh) and isosafrol (is ... | 1992 | 1503422 |
| the lipid a biosynthesis mutation lpxa2 of escherichia coli results in drastic antibiotic supersusceptibility. | the conditionally lethal lpxa2 mutant of escherichia coli, which lacks detectable udp-n-acetylglucosamine acyltransferase activity and which produces greatly reduced amounts of lipid a after a shift to 42 degrees c (s. galloway and c. r. h. raetz, j. biol. chem. 265:6394-6402, 1990), was found to be, at conditions which promote normal growth, remarkably susceptible to a number of antibiotics. the mics of hydrophobic antibiotics, such as rifampin, erythromycin, clindamycin, and fusidic acid, were ... | 1992 | 1503445 |
| associations of the bacterial mutagenicity of halogenated 2(5h)-furanones with their mndo-pm3 computed properties and mode of reactivity with sodium borohydride. | electrophilicity as a general basis for both the mutagenicity and nucleophile inactivation of halogen-substituted 2(5h)-furanones was tested. lowest unoccupied molecular orbital (lumo) energy levels and stabilities of 2(5h)-furanone radical anions and c-2, c-3, and c-4 anionic hydride adducts were computed with mndo-pm3 for each of 10 compounds. these three computed sets of values were considered electrophilicity indicators. each individual value from a given indicator set was plotted against th ... | 1992 | 1504263 |
| mutagenic activation of benzidine requires prior bacterial acetylation and subsequent conversion by prostaglandin h synthase to 4-nitro-4'-(acetylamino)biphenyl. | we have used the ames test in combination with prostaglandin h synthase (phs) to study the bioactivation of benzidine as well as other aromatic amines. previous investigations established that the formation of benzidine mutagens by phs is dramatically enhanced in salmonella typhimurium strains with high levels of acetyl coa-dependent arylamine n-acetyltransferase/arylhydroxylamine o-acetyltransferase activity despite the fact that acetylation of aromatic amines decreases their susceptibility to ... | 1992 | 1504268 |
| overexpression of the dcta gene in rhizobium meliloti: effect on transport of c4 dicarboxylates and symbiotic nitrogen fixation. | symbiotic nitrogen fixation may be limited by the transport of c4 dicarboxylates into bacteroids in the nodule for use as a carbon and energy source. in an attempt to increase dicarboxylate transport, a plasmid was constructed in which the rhizobium meliloti structural transport gene dcta was fused to a tryptophan operon promoter from salmonella typhimurium, trppo. this resulted in a functional dcta gene that was no longer under the control of the dctbd regulatory genes, but the recombinant plas ... | 1992 | 1504920 |
| comparison of permuted region lengths in the genomes of related salmonella typhimurium phages p22 and l. | lengths of permuted regions in the p22 and l phage genomes were estimated from the relative yields of dna in many electrophoretic bands obtained using several restriction endonucleases. it was found that 3.6 kb (8.7%) of p22-dna and 7.2 kb (17.8%) of l-dna were circularly permuted. in both phages the sequential packaging process proceeded in the same direction and four headful-size dna molecules were, on the average, cleaved in one packaging series. the differences in circular permutation may or ... | 1992 | 1505880 |
| cloning and nucleotide sequence of the ptsg gene of bacillus subtilis. | the ptsg gene of bacillus subtilis encodes enzyme iiglc of the phosphoenolpyruvate: glucose phosphotransferase system. the 3' end of the gene was previously cloned and the encoded polypeptide found to resemble the enzymes iiiglc of escherichia coli and salmonella typhimurium. we report here cloning of the complete ptsg gene of b. subtilis and determination of the nucleotide sequence of the 5' end. these results, combined with the sequence of the 3' end of the gene, revealed that ptsg encodes a p ... | 1992 | 1508157 |
| intracellular activity of zidovudine (3'-azido-3'-deoxythymidine, azt) against salmonella typhimurium in the macrophage cell line j774-2. | the antibacterial effect of zidovudine (azt) has been demonstrated both in vitro and in vivo with experimental models of gram-negative bacterial infections. it has been associated with the absence or low occurrence of nontyphoid salmonella infections in aids patients treated with azt. using the macrophage cell line j774-2, we demonstrate the inhibition of intracellular growth of salmonella typhimurium by azt. this effect is obtained with one-half of the mic (1 microgram/ml) of azt for s. typhimu ... | 1992 | 1510397 |
| mechanisms of antibacterial action of tachyplesins and polyphemusins, a group of antimicrobial peptides isolated from horseshoe crab hemocytes. | tachyplesins i and ii and polyphemusins i and ii, cationic peptides isolated from the hemocytes of horseshoe crabs, show bactericidal activities with similar efficiencies for both gram-negative and gram-positive bacteria. tachyplesin i inhibited bacterial growth irreversibly within 40 min. a subinhibitory concentration of tachyplesin i sensitized gram-negative bacteria to the bactericidal actions of novobiocin and nalidixic acid, although polymyxin b-resistant strains which have altered lipopoly ... | 1992 | 1510441 |
| characterization of tryptophan and coenzyme luminescence in tryptophan synthase from salmonella typhimurium. | tryptophan synthase from salmonella typhimurium is a bifunctional alpha 2 beta 2 complex that catalyzes the formation of l-tryptophan. we have characterized over the temperature range from 160 to 293 k the fluorescence and phosphorescence properties of the single tryptophan present at position 177 of the beta-subunit and of the pyridoxal 5'-phosphate bound through a schiff's base in the beta-active site. the comparison between the fluorescence of the pyridoxal phosphate bound either to the prote ... | 1992 | 1510939 |
| conformational changes and subunit communication in tryptophan synthase: effect of substrates and substrate analogs. | the transmission of regulatory signals between the alpha- and beta-subunits of the tryptophan synthase alpha 2 beta 2 complex from salmonella typhimurium has been investigated by monitoring the luminescence properties of the enzyme in the presence and in the absence of the alpha-subunit ligand dl-alpha-glycerol 3-phosphate, the alpha- and beta-subunit substrate indole, and the beta-subunit substrate analog l-histidine. the beta-subunit contains as intrinsic probes trp-177 and pyridoxal 5'-phosph ... | 1992 | 1510940 |
| importance of lysine-286 at the nadp site of glutamate dehydrogenase from salmonella typhimurium. | affinity labeling studies of nadp(+)-glutamate dehydrogenase from salmonella typhimurium have shown that the peptide leu-282-lys-286 is located near the coenzyme site [haeffner-gormley et al. (1991) j. biol. chem. 266, 5388-5394]. the present study was undertaken to evaluate the role of lysine-286. the mutant enzymes k286r, k286q, and k286e were prepared by site-directed mutagenesis, expressed in escherichia coli, and purified. the vmax values (micromoles of nadph per minute per milligram of pro ... | 1992 | 1510967 |
| a study of tobacco carcinogenesis. xlvii. bioassays of vinylpyridines for genotoxicity and for tumorigenicity in a/j mice. | 3-vinylpyridine is formed from nicotine during the smoking of tobacco products. consequently it is found in mainstream and side-stream smoke of cigarettes and cigars and in environmental tobacco smoke. in this study, 3-vinylpyridine and its isomers 2- and 4-vinylpyridine as well as styrene (vinylbenzene) were bioassayed for mutagenicity in salmonella typhimurium strains ta 1535, ta 1538, ta 98 and ta 100 and for their genotoxicity in the rat hepatocyte dna-repair test. in both in vitro assays-al ... | 1992 | 1511414 |
| integration host factor facilitates repression of the put operon in salmonella typhimurium. | transcriptional regulation of the put operon is mediated by a unique mechanism involving autogenous regulation by the puta protein, a membrane-associated dehydrogenase. the 420-bp put control region contains the putp and puta promoters, multiple operator sites, multiple catabolite repression protein binding sites, and several potential integration host factor (ihf)-binding sites (ihf). in this study, we show that ihf facilitates repression of the put operon in vivo, and ihf binds specifically to ... | 1992 | 1511875 |
| differences between rats and mice in the immunosuppressive activity of 2-methoxyethanol and 2-methoxyacetic acid. | previous studies from this laboratory have demonstrated that 2-methoxyethanol (me) and its principal metabolite 2-methoxyacetic acid (maa) are immunosuppressive in young adult male fischer 344 rats. in the present study, the immunosuppressive potential of me and maa was evaluated in young adult female fischer 344 rats and c57bl/6j mice. rats and mice were dosed by gavage with either me or maa in water, at dosages ranging from 50-400 mg/kg/day, for 10 consecutive days. rats and mice were examined ... | 1992 | 1514188 |
| characterization of bacteriocins from two strains of bacillus thermoleovorans, a thermophilic hydrocarbon-utilizing species. | bacillus thermoleovorans s-ii and b. thermoleovorans nr-9 produce bacteriocins, and these bacteriocins are designated thermoleovorin-s2 and thermoleovorin-n9, respectively. the bacteriocins are effective against all but the producing strain of b. thermoleovorans, as well as being effective against salmonella typhimurium, branhamella catarrhalis, streptococcus faecalis, and thermus aquaticus. thermoleovorins are produced during log-phase growth and are inhibitory to actively growing cells. the ba ... | 1992 | 1514786 |
| immunosuppression induced by nitric oxide and its inhibition by interleukin-4. | mice immunized with attenuated salmonella typhimurium, strain sl3235, while protected against virulent challenge, are unable to mount in vivo and in vitro antibody responses to non-salmonella antigens, such as tetanus toxoid and sheep red blood cells, and exhibit profoundly suppressed responses to b and t cell mitogens. suppression of antibody responses is mediated by macrophage (m phi)-released soluble factors, and is completely reversed by treatment with interleukin (il)-4. the present report ... | 1992 | 1516618 |
| peptidyl-prolyl cis-trans isomerase from bacillus subtilis. a prokaryotic enzyme that is highly sensitive to cyclosporin a. | cyclophylins are members of a class of proteins with peptidyl-prolyl cis-trans isomerase activity. these enzymes bind the immunosuppressive agent, cyclosporin a (csa), which acts as a competitive inhibitor. the peptidyl-prolyl cis-trans isomerase from bacillus subtilis (ppiase) was purified to homogeneity in a 4-step purification procedure, which resulted in a 100-fold protein purification with a yield of 5%. coomassie blue-stained sds-page revealed a single band of about 18 kda. ppiase activity ... | 1992 | 1516692 |
| clastogenic and mutagenic actions of active species generated in the 6-hydroxydopamine/oxygen reaction: effects of scavengers of active oxygen, iron, and metal chelating agents. | a pro-oxidant triphenol, 6-hydroxydopamine (6-ohda), induced mutations in the salmonella typhimurium ta 104 tester strain (over the concentration range to 800 microm), and induced chromosomal aberrations in cultured chinese hamster ovary (cho) cells at lower concentrations (up to 90 microm). it was however only marginally mutagenic (up to cytotoxic levels of 200 microm) in the ta102 tester strain. clastogenicity in the more sensitive cho cell assay was mediated by activated oxygen. superoxide di ... | 1992 | 1516844 |
| purification, crystallization and preliminary crystallographic study of neuraminidase from vibrio cholerae and salmonella typhimurium lt2. | the nanh genes of vibrio cholerae and salmonella typhimurium lt2 coding neuraminidase were cloned separately in escherichia coli, and the expression products purified. single crystals of the v. cholerae neuraminidase were obtained using the hanging drop vapour diffusion method with polyethylene glycol as precipitant at ph 7.2. the crystals belong to the orthorhombic space group p2(1)2(1)2(1), with unit cell dimensions a = 71.9 a, b = 79.0 a, c = 165.7 a, and with one molecule in the asymmetric u ... | 1992 | 1518058 |
| molecular cloning and bacterial expression of cdna encoding a plant cysteine synthase. | cysteine synthase (csase) [o-acetyl-l-serine acetate-lyase (adding hydrogen sulfide), ec 4.2.99.8] catalyzes the formation of l-cysteine, the key step in sulfur assimilation in plants, from o-acetyl-l-serine and hydrogen sulfide. we report here the isolation and characterization of cdna clones encoding cysteine synthase from spinach (spinacia oleracea l.). internal peptide sequences were obtained from v8 protease-digested fragments of purified csase. a lambda gt10 cdna library was constructed fr ... | 1992 | 1518833 |
| oligopeptidase a is required for normal phage p22 development. | the opda gene of salmonella typhimurium encodes an endoprotease, oligopeptidase a (opda). strains carrying opda mutations were deficient as hosts for phage p22. p22 and the closely related phages l and a3 formed tiny plaques on an opda host. salmonella phages 9na, kb1, and es18.h1 were not affected by opda mutations. although opda strains displayed normal doubling times and were infected by p22 as efficiently as opda+ strains, the burst size of infectious particles from an opda host was less tha ... | 1992 | 1522065 |
| mechanism of resistance to complement-mediated killing of bacteria encoded by the salmonella typhimurium virulence plasmid gene rck. | we find that padeo16, a recombinant cosmid carrying the rck gene of the salmonella typhimurium virulence plasmid, when cloned into either rough or smooth escherichia coli and salmonella strains, confers high level resistance to the bactericidal activity of pooled normal human serum. the rck gene encodes a 17-kd outer membrane protein that is homologous to a family of virulence-associated outer membrane proteins, including pagc and ail. complement depletion, c3 and c5 binding, and membrane-bound ... | 1992 | 1522243 |
| a critical evaluation of the present status of toxicity of aminoxyl radicals. | the literature on the toxicity of aminoxyl radicals was critically reviewed. it was concluded that, in general, the aminoxyl radicals possess a very low toxicity and are not mutagenic. in support of this contention, several aminoxyl radicals were evaluated in vitro. thus, aminoxyl radicals 3-carboxy-2,2,5,5-tetramethylpyrroline-1-oxyl (1), 3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl (pca; 2), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol;3), and n-(1-hydroxymethyl-2,3-dihydroxypropy ... | 1992 | 1522484 |
| populations of salmonella typhimurium in internal organs of experimentally infected carrier swine. | experiments were conducted to determine comparative populations of salmonella typhimurium in the most commonly infected body organs of long-term carrier swine. naturally farrowed salmonella-free pigs (n = 58) were orally exposed to s typhimurium when they were 47 days old. necropsy of 3 to 5 randomly selected pigs was conducted at 3, 7, 10, 14, and 17 days and at 3, 4, 5, 6, 8, 12, 16, 20, 24, and 28 weeks after exposure. mean populations (log10/g) of s typhimurium in palatine tonsils, ileum, ce ... | 1992 | 1524288 |
| biological inactivation by singlet oxygen: distinguishing o2(1 delta g) and o2(1 sigma g+) | experiments were performed to determine whether bacterial inactivation in the separated-surface-sensitizer system for singlet oxygen generation is due to o2(1 delta g) or o2(1 sigma g+). the rates of inactivation of gram-negative salmonella typhimurium lt-2 and a nonpigmented strain of gram-positive sarcina lutea were found to increase linearly with the concentration of 1 delta g. the gas phase lifetime of the inactivating agent was found to be within the range of values expected for the gas pha ... | 1992 | 1525183 |
| synthesis of dibenzoylmethane derivatives and inhibition of mutagenicity in salmonella typhimurium. | twenty dibenzoylmethanes with methyl, methoxy, bromo, chloro, or fluoro substitution on either one or both benzene rings were synthesized and assayed for inhibition of the mutagenicity of 2-nitrofluorene in s. typhimurium ta98. 2,2-dimethoxy, 3,3-dimethoxy and 3,3,4,4-tetramethoxydibenzoylmethane was as active as dibenzoylmethane. none of the halogen-substituted dibenzoylmethanes were active. these results demonstrate that dibenzoylmethanes can inhibit the mutagenicity of 2-nitrofluorene, and th ... | 1992 | 1525933 |
| genotoxic properties of (e)-5-(2-bromovinyl)-2'-deoxyuridine (bvdu). | (e)-5-(2-bromovinyl)-2'-deoxyuridine (bvdu)is a 5-substituted 2'-deoxyuridine antiviral compound that inhibits thymidylate synthetase. the selectivity of bvdu for virus-infected cells has been attributed to phosphorylation of bvdu by a virus-induced thymidine kinase. since the closely related compounds 5-bromo-2'-deoxyuridine and 5-iodo-2'-deoxyuridine are in vitro and in vivo mutagens, bvdu was tested for genotoxic activity in bacterial and mammalian cell mutation assays as well as in assays me ... | 1992 | 1526360 |
| salmonella typhimurium induces an inositol phosphate flux in infected epithelial cells. | salmonella typhimurium, like many other intracellular pathogens, is capable of inducing its own uptake into non-phagocytic cells by a process termed invasion, and residing within a membrane-bound inclusion. during invasion it causes significant rearrangement of the host cytoskeleton, indicating that signals are transduced between the bacterium and the host cell cytoplasm, across the eukaryotic cell membrane. we found that intracellular inositol phosphate concentrations in hela cells increased du ... | 1992 | 1526443 |
| resistance of the melibiose carrier to inhibition by the phosphotransferase system due to substitutions of amino acid residues in the carrier of salmonella typhimurium. | the melibiose carrier of salmonella typhimurium is under the control of the phosphoenolpyruvate:carbohydrate phosphotransferase system (pts). we isolated mutants of the melibiose carrier that showed resistance to inhibition via the pts. growth of the mutants on melibiose was not inhibited by 2-deoxyglucose, a non-metabolizable substrate of the pts, although growth of the parent strain was inhibited. transport activity of the melibiose carrier in the mutants was fairly resistant to inhibition by ... | 1992 | 1526973 |
| the rfac gene of salmonella typhimurium. cloning, sequencing, and enzymatic function in heptose transfer to lipopolysaccharide. | we have cloned a gene from a salmonella typhimurium with the ability to complement the rfac mutation (heptose-deficient lipopolysaccharide, sensitivity to rough-specific bacteriophages, and susceptibility to hydrophobic antibiotics). a 1018-base pair ecorv-tth111i fragment, subcloned into the pbluescriptks+ vector to yield pkz103, retains complementing activity. nucleotide sequencing revealed an open reading frame corresponding to a protein of 317 amino acids (m(r) approximately 35,100). the pla ... | 1992 | 1527014 |
| subdivision of flagellar region iii of the escherichia coli and salmonella typhimurium chromosomes and identification of two additional flagellar genes. | the many genes involved in flagellar structure and function in escherichia coli and salmonella typhimurium are located in three major clusters on the chromosome: flagellar regions i, ii and iii. we have found that region iii does not consist of a contiguous set of flagellar genes, as was thought, but that in e. coli there is almost 7 kb of dna between the filament cap gene, flid, and the next known flagellar gene, flie; a similar situation occurs in s. typhimurium. most of this dna is unrelated ... | 1992 | 1527488 |
| amplification of an inva gene sequence of salmonella typhimurium by polymerase chain reaction as a specific method of detection of salmonella. | amplification of nucleotide sequences within the inva gene of salmonella typhimurium was evaluated as a means of detecting salmonella. a collection of 630 strains of salmonella comprising over 100 serovars, including the 20 most prevalent serovars isolated from animals and humans in canada, was examined. controls consisted of 142 non-salmonella strains comprising 21 genera of bacteria. cultures were screened by inoculating a single colony of bacteria directly into a polymerase chain reaction (pc ... | 1992 | 1528198 |
| activation of 6-aminochrysene to genotoxic products by different forms of rat liver cytochrome p450 in an o-acetyltransferase-overexpressing salmonella typhimurium strain (nm2009). | metabolic activation of a potent mutagen, 6-aminochrysene, to genotoxic products in a newly developed tester strain, salmonella typhimurium nm2009, was studied in a rat liver microsomal monooxygenase system containing cytochrome p450 (p450). since the tester strain was constructed by introducing an o-acetyltransferase gene into the original strain s. typhimurium ta1535/psk1002, it is highly sensitive toward the reactive metabolites of carcinogenic arylamines. dna-damaging activities of 6-aminoch ... | 1992 | 1530660 |
| molecular genetic analysis of the escherichia coli phop locus. | we have cloned the escherichia coli phop gene, a member of the family of environmentally responsive two-component systems, and found its deduced amino acid sequence to be 93% identical to that of the salmonella typhimurium homolog, which encodes a major virulence regulator necessary for intramacrophage survival and resistance to cationic peptides of phagocytic cells. the phop gene was mapped to kilobase 1202 on the kohara map (25-min region) of the e. coli genome (y. kohara, k. akiyama, and k. i ... | 1992 | 1530848 |
| large scale purification, nucleotide binding properties, and atpase activity of the malk subunit of salmonella typhimurium maltose transport complex. | the malk gene, encoding a membrane-associated component of the maltose transport complex of salmonella typhimurium was cloned into an expression vector downstream of the promoters lambda pr and lambda pl and a strong translation initiation region. escherichia coli strain jm109 harboring the resulting plasmid pcw14 synthesized a protein of apparent molecular mass of 43 kda upon temperature shift, as demonstrated by sodium dodecyl sulfate-gel electrophoresis. the identity of the protein was determ ... | 1992 | 1533621 |
| development and duration of protection against salmonellosis in mice and sheep immunised with live aromatic-dependent salmonella typhimurium. | the aim of this investigation was to determine the development and duration of protection in mice or sheep immunised with aromatic-dependent (aro-) salmonella typhimurium strain cs332, by either parenteral or oral routes. immunisation of mice by the intraperitoneal or sheep by the intramuscular routes was found to impart protection against oral challenge with the virulent parent s typhimurium strain cs94 as early as seven days after immunisation. in contrast, when immunisation was carried out by ... | 1992 | 1533950 |
| the role of ntra in the anaerobic metabolism of salmonella typhimurium. | the possible involvement of ntra in the expression of several anaerobically induced genes in salmonella typhimurium was investigated. unlike escherichia coli, where hydrogenase 3 is ntra dependent, the introduction of a mutation in ntra had virtually no effect on the hydrogenase activity, thought to be hydrogenase 3, of s. typhimurium lt7. fumarate reductase and alcohol dehydrogenase activities were found to be diminished in ntra mutant strains, but this may very well be indirect since fdhf muta ... | 1992 | 1537537 |
| evidence for a new, oxygen-regulated biosynthetic pathway for the pyrimidine moiety of thiamine in salmonella typhimurium. | the synthesis of the pyrimidine moiety of thiamine (vitamin b1) shares five reactions with the de novo purine biosynthetic pathway. aminoimidazole ribotide (air) is the last common intermediate before the two pathways diverge. evidence for the existence of a new pathway to the pyrimidine which bypasses the de novo purine biosynthetic pathway is reported here. this pathway is only expressed under anaerobic growth conditions and is denoted alternative pyrimidine biosynthesis or apb. labeling studi ... | 1992 | 1537796 |
| cloning and nucleotide sequence of the salmonella typhimurium dcp gene encoding dipeptidyl carboxypeptidase. | plasmids carrying the salmonella typhimurium dcp gene were isolated from a pbr328 library of salmonella chromosomal dna by screening for complementation of a peptide utilization defect conferred by a dcp mutation. strains carrying these plasmids overproduced dipeptidyl carboxypeptidase approximately 50-fold. the nucleotide sequence of a 2.8-kb region of one of these plasmids contained an open reading frame coding for a protein of 77,269 da, in agreement with the 80-kda size for dipeptidyl carbox ... | 1992 | 1537804 |
| cloning and nucleotide sequence of opda, the gene encoding oligopeptidase a in salmonella typhimurium. | the opda gene (formerly called opta) of salmonella typhimurium encodes a metallopeptidase, oligopeptidase a (opda), first recognized by its ability to cleave and allow utilization of n-acetyl-l-ala4 (e. r. vimr, l. green, and c. g. miller, j. bacteriol. 153:1259-1265, 1983). derivatives of pbr328 carrying the opda gene were isolated and shown to express oligopeptidase activity at levels approximately 100-fold higher than that of the wild type. these plasmids complemented all of the phenotypes as ... | 1992 | 1537805 |
| fish oil decreases natural resistance of mice to infection with salmonella typhimurium. | mortality rate in mice fed fish oil for 4 weeks was remarkably higher after a very low peroral (po) challenge with salmonella typhimurium, as compared with those fed diets rich in either corn oil or hydrogenated coconut oil, or a low fat (chow) diet. none of the surviving mice fed the fish oil diet showed bacterial counts in their spleens, unlike 45.4% to 66.6% of surviving mice fed high fat or low fat diets. the spleens of mice fed fish oil presented the highest number of bacteria 7 days after ... | 1992 | 1538638 |
| influence of coccidiosis on salmonella colonization in broiler chickens under floor-pen conditions. | the influence of coccidiosis on colonization of salmonella typhimurium in broiler chickens under floor pen conditions was studied by semiquantitative methods. chickens of two groups, unmedicated and medicated with nicarbazin (125 ppm via the feed), were exposed to three species of eimeria (eimeria tenella, eimeria maxima, and eimeria acervulina) at 2, 3, and 4 wk of age and given s. typhimurium in the feed 2 days later. salmonella typhimurium was isolated most often (100%) from ceca of chickens ... | 1992 | 1539023 |
| analysis of the genotoxicity of municipal solid waste incinerator ash. | combined bottom and fly ash obtained from a chicago, il, municipal solid waste incinerator (mswi) was extracted with organic solvents, water or acidified water. the mean amounts of organic material isolated from each extraction procedure were 688.2, 91.8 and 167.7 micrograms/g mswi ash. these extracts were evaluated for toxicity and mutagenicity in salmonella typhimurium strains ta98 and ta100. we developed and calibrated a micropreincubation assay to evaluate small concentrations of the organic ... | 1992 | 1539127 |
| humoral and cell-mediated immunity in mice after immunization with live oral vaccines of salmonella typhimurium: auxotrophic mutants with two attenuating markers. | persistence and clearance of the vaccinal strains, humoral and cell-mediated immune response and protective immunity were assessed in icr mice, immunized intraperitoneally or intragastrically with double-marker auxotrophic mutants of salmonella typhimurium strains 1771 and 3334 (his-pur-). strain 3334 possesses in addition the antiepidemic hst (high sensitivity to tensides) marker which confers decreased survival in the gut and environment. the results showed that the strains are not overattenua ... | 1992 | 1539461 |
| phagocytic and bactericidal function of mouse macrophages to salmonella typhimurium in schistosomiasis mansoni. | patients infected with schistosomes may develop a clinical picture of chronic salmonellosis. we have investigated the altered function of macrophages capable of playing a role in the development of chronic salmonellosis associated with schistosoma mansoni in an experimental model. the capacity of mouse peritoneal macrophages to ingest and kill salmonella was assessed in mice infected with s. mansoni with or without concurrent salmonella typhimurium infection. schistosomiasis was associated with ... | 1992 | 1539746 |
| amino acid replacements can selectively affect the interaction energy of autonomous folding units in the alpha subunit of tryptophan synthase. | amino acid replacements were made at the interface between two autonomous folding units in the alpha subunit of tryptophan synthase from salmonella typhimurium to test their mutual interaction energy. the results of equilibrium studies of the urea-induced unfolding reaction of the wild-type and mutant proteins in which phenylalanine 22 is replaced by leucine, isoleucine, and valine can be understood in terms of a selective decrease in the interaction energy between the two folding units; the int ... | 1992 | 1540577 |
| fecapentaene excretion and fecal mutagenicity in relation to nutrient intake and fecal parameters in humans on omnivorous and vegetarian diets. | fecapentaenes are strong fecal mutagenic compounds presumably occurring in the majority of western human individuals, and are possibly essential initiators of colon carcinogenesis. dietary factors have been shown to influence colorectal cancer risk and to modulate both fecal mutagenicity and fecapentaene concentrations. therefore, in this study, excretion of fecapentaenes is determined in humans consuming either vegetarian or omnivorous diets. the results show that the most predominant fecapenta ... | 1992 | 1540928 |
| chinese medicinal herbs modulate mutagenesis, dna binding and metabolism of benzo[a]pyrene 7,8-dihydrodiol and benzo[a]pyrene 7,8-dihydrodiol-9,10-epoxide. | oldenlandia diffusa(od) and scutellaria barbata (sb) have been used in traditional chinese medicine for treating liver, lung and rectal tumors. in this study, the effects of aqueous extracts of these two herbs on benzo[a]pyrene 7,8-dihydrodiol. (bap 7,8-dhd) and benzo[a]pyrene 7,8-dihydrodiol-9,10-epoxide (bpde)-induced mutagenesis using salmonella typhimurium ta100 as the bacterial tester strain and rat liver 9000 x g supernatant (s9) as the metabolic activation system were assessed. we also de ... | 1992 | 1540939 |
| metal, mutagenicity, and biochemical studies on bivalve molluscs from spanish coasts. | three species of marine bivalve molluscs (chamelea gallina, ruditapes decussatus, and crassostrea gigas) have been studied in order to evaluate the levels of pollution on the south atlantic spanish littoral. several transition metals (cu, as, cd, sn, hg, pb) were determined as a general index of total contamination. animals from putative contaminated areas exhibited higher metal contents than those from cleaner waters. c. gigas showed 5-20-fold higher total metal content than the other two speci ... | 1992 | 1541252 |
| conditions for detecting the mutagenicity of divalent metals in salmonella typhimurium. | the mutagenesis of metals in bacteria, as reported in the literature, can best be described as inconsistent. we report that cobalt chloride (co++), ferrous sulfate (fe++), manganese sulfate (mn++), cadmium chloride (cd++), and zinc chloride (zn++) could be reproducibly detected as mutagens in salmonella strain ta97 when preincubation exposures were made in sterile, distilled, deionized water, or in hepes buffer in nacl2/kcl2, rather than the standard sodium phosphate buffer. co++ was also mutage ... | 1992 | 1541255 |
| evaluation of the mutagenic and genotoxic activities of 48 nitroimidazoles and related imidazole derivatives by the ames test and the sos chromotest. | the mutagenic and genotoxic activities of 48 nitroimidazoles and related imidazole derivatives have been evaluated by using modified versions of the ames test and the sos chromotest. salmonella typhimurium tester strain ta 100 was used with and without metabolic activation in the ames test and escherichia coli tester strain pq 37 was used with and without metabolic activation in the sos chromotest. including metronidazole and dimetridazole, 45 derivatives were mutagenic and genotoxic. the mutage ... | 1992 | 1541258 |
| salmonella mutagenicity tests: v. results from the testing of 311 chemicals. | 311 chemicals were tested under code, for mutagenicity, in salmonella typhimurium; 35 of the chemicals were tested more than once in the same or different laboratories. the tests were conducted using a preincubation protocol in the absence of exogenous metabolic activation, and in the presence of liver s-9 from aroclor-induced male sprague-dawley rats and syrian hamsters. some of the volatile chemicals were also tested in desiccators. a total of 120 chemicals were mutagenic or weakly mutagenic, ... | 1992 | 1541260 |
| natural killer cells mediate protection induced by a salmonella aroa mutant. | we have previously shown that an avirulent strain of salmonella typhimurium, sl3235, blocked in aromatic synthesis, confers high levels of resistance to challenge with virulent salmonella as early as 3 days postvaccination. in the present studies, it was found that immunization with sl3235 resulted in high levels of natural killer (nk) cell activity in the spleens and peritoneal cavities of c3h/hej mice, as measured by cytotoxicity against yac-1 targets. nk cell activity was at its maximum 2 to ... | 1992 | 1541553 |
| contribution of interferon gamma and membrane-associated interleukin 1 to the resistance to murine typhoid of ityr mice. | resistance of mice to salmonella typhimurium in the early phase of infection is known to be controlled by the expression of chromosome 1 locus ity. to clarify the mechanism by which the genetically resistant (ityr) mice can overcome the first phase of salmonellosis, the early response in dba/2 (ityr) and balb/c (itys) mice was compared after a subcutaneous injection of s. typhimurium. in both strains, the growth of s. typhimurium was controlled in livers and kupffer cells until day 3, but therea ... | 1992 | 1541907 |
| oxyr: a regulator of antioxidant genes. | the study of the bacterial response to hydrogen peroxide has given general insights into how cells defend against deleterious oxidants. treatment of salmonella typhimurium and escherichia coli cells with low doses of hydrogen peroxide results in the induction of 30 proteins and resistance to killing by higher doses of hydrogen peroxide. the expression of nine of the hydrogen peroxide-inducible proteins, including the antioxidant enzymes catalase, glutathione reductase and an alkyl hydroperoxide ... | 1992 | 1542022 |
| sequence and complementation analysis of recf genes from escherichia coli, salmonella typhimurium, pseudomonas putida and bacillus subtilis: evidence for an essential phosphate binding loop. | we have compared the recf genes from escherichia coli k-12, salmonella typhimurium, pseudomonas putida, and bacillus subtilis at the dna and amino acid sequence levels. to do this we determined the complete nucleotide sequence of the recf gene from salmonella typhimurium and we completed the nucleotide sequence of recf gene from pseudomonas putida begun by fujita et al. (1). we found that the recf proteins encoded by these two genes contain respectively 92% and 38% amino acid identity with the e ... | 1992 | 1542576 |
| repair of dna heteroduplexes containing small heterologous sequences in escherichia coli. | plasmid heteroduplexes were constructed that contain 1, 2, 3, 4, or 5 unpaired bases within the mnt gene. these were used to assess the efficiency of repair of small heterologous sequences ("heterologies") in dna by the escherichia coli dam-directed mismatch repair system. heteroduplexes in defined states of methylation at d(gatc) sites were used to transform a repair-proficient indicator strain (which has a mnt-lac fusion coding for a nonfunctional mnt repressor) and its isogenic muth, -l, and ... | 1992 | 1542666 |
| effects of dietary lactose on incidence and levels of salmonellae on carcasses of broiler chickens grown to market age. | two trials were conducted to evaluate the effects of lactose in the diet of broilers grown to market weights on incidence and levels of salmonellae on the carcass. lactose was substituted for sand in otherwise nutritionally complete diets at levels of 0, 2.5, 5, and 7.5% and fed from day-old to 49 days of age. birds were reared on used (trial 1) or new (trial 2) litter and inoculated via the drinking water on days 2, 7, and 14 with 10(8) cfu/ml salmonella typhimurium (atcc 14028). at 50 days, 12 ... | 1992 | 1546039 |
| differential myelopoietic responsiveness of balb/c (itys) and c.d2 (ityr) mice to lipopolysaccharide administration and salmonella typhimurium infection. | inheritance of the ityr or the itys allele of the ity murine gene confers resistance or increased susceptibility, respectively, to salmonella typhimurium infection. recent studies have documented that ity gene expression may determine net intracellular replication of s. typhimurium by modulating macrophage function. the purpose of this study was to determine if ity gene expression modulated macrophage stem cell proliferation as well. to detect possible ity-associated alterations in macrophage st ... | 1992 | 1548063 |
| use of recombinant interleukin-2 to enhance adoptive transfer of resistance to listeria monocytogenes infection. | in vitro incubation of listeria-immune spleen cells (lisc) with recombinant interleukin-2 (ril-2) for at least 3 days increased their ability to transfer antilisteria resistance to recipient mice. this effect was blocked by the in vitro addition of transforming growth factor beta 1. the level of protection afforded by the transfer of ril-2-incubated lisc was further elevated by the in vivo administration of ril-2 at a dose that by itself did not significantly increase antilisteria resistance. th ... | 1992 | 1548066 |
| stimulation of human monocytes by endotoxin-associated protein: inhibition of programmed cell death (apoptosis) and potential significance in adjuvanticity. | mononuclear phagocytes are essential for adjuvant activity and polyclonal immunoglobulin synthesis induced by endotoxin-associated protein (ep) from salmonella spp. to define the mechanisms of ep-mediated immunostimulation, we evaluated monocyte functions central to adjuvanticity following exposure to salmonella typhimurium ep. in this study, we show that ep promotes the survival of monocytes by blocking programmed cell death (apoptosis), enhancing the production of the immunostimulatory cytokin ... | 1992 | 1548091 |
| overexpression, purification, and some properties of the adocbl-dependent ethanolamine ammonia-lyase from salmonella typhimurium. | recombinant ethanolamine ammonia-lyase from s. typhimurium has been overexpressed and purified in large quantities by a simple procedure. the molecular weight of the native enzyme is about 480 kda, and it contains two active sites/molecule as shown by kinetic studies and by titration with cncbl. analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirms earlier cloning studies indicating that it is composed of two kinds of subunits, one of mw 31 kda and the other of mw 50 kda ... | 1992 | 1550360 |
| human mannose-binding protein is identical to a component of ra-reactive factor. | human ra-reactive factor (rarf) and mannose-binding protein (mbp) were isolated from sera by utilizing their affinity to ra chemotype salmonella typhimurium and yeast mannan, respectively. a predominant polypeptide of human rarf with an mr of 32 kda (p32) has the same mobility as human mbp on sds-page gels. a monoclonal antibody against p32 of human rarf, 3e7, was found to react not only with p32 but also with human mbp, as assessed by immunoblotting. in addition, 3e7 blocked the complement-acti ... | 1992 | 1550571 |
| reconstitution of the binding protein-dependent galactose transport of salmonella typhimurium in proteoliposomes. | binding protein-dependent transport systems mediate the accumulation of diverse substrates in bacteria. the binding protein-dependent galactose transport of salmonella typhimurium has been reconstituted in proteoliposomes. the proteoliposomes were made with proteins solubilized and renatured from inclusion bodies produced by a bacterial strain containing a plasmid with the mgl (methylgalactose permease) operon of salmonella typhimurium. galactose transport is dependent both on the addition of th ... | 1992 | 1550848 |
| roles of human liver cytochrome p4502c and 3a enzymes in the 3-hydroxylation of benzo(a)pyrene. | the major oxidation product of the classic polycyclic hydrocarbon carcinogen benzo(a)pyrene [b(a)p] is 3-hydroxy b(a)p. numerous studies have been concerned with the measurement of b(a)p 3-hydroxylation activity in experimental animals and human tissues. although human liver is the main site of this reaction, systematic studies had not been carried out to define the roles of individual cytochrome p-450 (p-450) enzymes involved. purified human p4502c8 and p4503a4 showed appreciable catalytic acti ... | 1992 | 1551116 |
| preferential synthesis of heptaacyl lipopolysaccharide by the ssc permeability mutant of salmonella typhimurium. | in salmonella typhimurium, a chromosomal gene termed ssc has been shown to cause an antibiotic-supersensitive phenotype. we studied the effect of the ssc gene on the chemical composition of the lipopolysaccharide component, using a thermosensitive ssc1 mutant (sh7622) that grows poorly at 42 degrees c. analysis of the lipopolysaccharide by various techniques including fast-atom-bombardment mass spectrometry of lipid a, and determination of the type of linkage of fatty acids, revealed a profound ... | 1992 | 1551389 |
| a salmonella typhimurium cobalamin-deficient mutant blocked in 1-amino-2-propanol synthesis. | salmonella typhimurium synthesizes cobalamin (vitamin b12) when grown under anaerobic conditions. all but one of the biosynthetic genes (cob) are located in a single operon which includes genes required for the production of cobinamide and dimethylbenzimidazole, as well as the genes needed to form cobalamin from these precursors. we isolated strains carrying mutations (cobd) which are unlinked to any of the previously described b12 biosynthetic genes. mutations in cobd are recessive and map at m ... | 1992 | 1551838 |
| characterization of the flie genes of escherichia coli and salmonella typhimurium and identification of the flie protein as a component of the flagellar hook-basal body complex. | within flagellar region iii of escherichia coli and salmonella typhimurium, the genomic organization has been largely established. an exception is flie, a gene whose exact location and product function are not well understood. we cloned the flie gene, obtained its dna sequence, and identified its product.flie was found to be a monocistronic transcriptional unit, adjacent to and divergent from the large flif operon. it is several kilobases distant from the nearest flagellar operon in the other di ... | 1992 | 1551848 |
| mutation spectrum and sequence alkylation selectivity resulting from modification of bacteriophage m13mp18 dna with s-(2-chloroethyl)glutathione. evidence for a role of s-(2-n7-guanyl)ethyl)glutathione as a mutagenic lesion formed from ethylene dibromide. | the major dna adduct (greater than 95% total) resulting from the bioactivation of ethylene dibromide by conjugation with gsh is s-(2-(n7-guanyl)ethyl)gsh. the mutagenic potential of this adduct has been uncertain, however, because the observed mutagenicity might be caused by other adducts present at much lower levels, e.g. s-(2-n1-adenyl)ethyl)gsh. to assess the formation of other potential adducts, s-(2-(n3-deoxycytidyl)ethyl)gsh, s-(2-(o6-deoxyguanosyl)ethyl)gsh, and s-(2-(n2-deoxyguanosyl)eth ... | 1992 | 1551876 |
| mapping, cloning, expression, and sequencing of the rhat gene, which encodes a novel l-rhamnose-h+ transport protein in salmonella typhimurium and escherichia coli. | a l-rhamnose transport-negative strain of escherichia coli was generated by mu d(apr,lac)i mutagenesis. this strain was used to isolate a clone of salmonella typhimurium dna that encoded l-rhamnose-h+ transport activity, the gene for which, rhat, was sequenced. the rhat gene was mapped on the e. coli chromosome between rhar and soda at 87.9 min, initially by southern blot analysis and then by the isolation, expression, and sequencing of the rhat gene. both rhat genes encoded a hydrophobic protei ... | 1992 | 1551902 |
| d-alanine: d-alanine ligase of escherichia coli. expression, purification and inhibitory studies on the cloned enzyme. | a 1.2 kb bamhi fragment from pdk30 [robinson, kenan, sweeney & donachie (1986) j. bacteriol. 167, 809-817] was cloned in pdoc55 [o'connor & timmis (1987) j. bacteriol. 169, 4457-4482] to give two constructs, pdoc89 and pdoc87, in which the escherichia coli d-alanine:d-alanine ligase (ec 6.3.2.4) gene (ddl) was placed under the control of the lac and lambda pl promoters respectively. both constructs, when used to transform e. coli m72, gave similar levels of expression of the ddl gene. the expres ... | 1992 | 1554356 |
| effect of ssc protein mutations on the outer membrane permeability barrier function in salmonella typhimurium: a study using ssc mutant alleles made by site-directed mutagenesis. | we have previously discovered and characterized a novel essential enterobacterial protein, the ssc protein of salmonella typhimurium and found that the mutation val291----met in this protein inhibits bacterial growth at 42 degrees c and the function of its outer membrane permeability barrier at 37 degrees c [7]. in the present paper we prepared, by site-directed mutagenesis, a series of novel plasmid-encoded ssc mutant proteins and tested their ability to compensate the loss of wild-type ssc. th ... | 1992 | 1555764 |
| antimutagenic effect of maillard browning products obtained from amino acids and sugars. | the antimutagenic effects of maillard reaction products (mrps) prepared by heating three sugars (fructose, glucose and xylose) and four amino acids (arginine, glycine, lysine and tryptophan) at 100 degrees c for 10 hr was evaluated in the salmonella/microsome assay. the highest extent of browning was found in the mrps of sugars-lysine and xylose-amino acids. the mrps of xylose-amino acids showed stronger antioxidative activity and reducing power than did the other combinations. no mutagenicity o ... | 1992 | 1555794 |
| purification and characterization of a tryptic peptide of borrelia burgdorferi flagellin, which reduces cross-reactivity in immunoblots and elisa. | in man the early immune response in lyme disease is primarily directed against the endoflagellin antigen. isolated flagellar protein of borrelia burgdorferi suggests itself as a suitable test antigen. however, cross-reactivity between flagellins of b. burgdorferi, escherichia coli, bacillus subtilis, proteus mirabilis and salmonella typhimurium was demonstrated by immunoblotting and elisa with polyclonal rabbit-hyperimmune-sera. tryptic cleavage of recombinant b. burgdorferi 41 kda flagellin, ex ... | 1992 | 1556546 |
| synthesis of 5-methylaminomethyl-2-selenouridine in trnas: 31p nmr studies show the labile selenium donor synthesized by the seld gene product contains selenium bonded to phosphorus. | an enzyme preparation from salmonella typhimurium catalyzes the conversion of 5-methylaminomethyl-2-thiouridine in trnas to 5-methylaminomethyl-2-selenouridine when supplemented with selenide and atp. similar preparations from a salmonella mutant strain carrying a defective seld gene fail to catalyze this selenium substitution reaction. however, supplementation of the deficient enzyme preparation with the purified seld gene product (seld protein) restored synthesis of seleno-trnas. in the absenc ... | 1992 | 1557403 |
| a transcriptional silencer downstream of the promoter in the osmotically controlled prou operon of salmonella typhimurium. | the prou operon of salmonella typhimurium is induced by conditions of high osmolality. the cis-acting sequences that mediate osmotic control of transcription were characterized by deletion analysis. the nucleotide sequence between -60 and +274 (relative to the transcription start point) is sufficient for normal osmotic control. deletions that removed sequences upstream of position +274 but left the promoter intact resulted in greatly increased expression from the prou promoter in the absence of ... | 1992 | 1557423 |
| [comparative plasmid profile analysis of salmonella typhimurium var. copenhagen strains from a salmonella outbreak in hospitalized horses]. | from april 1990 through june 1991 clinical salmonellosis and asymptomatic faecal excretion of salmonella spp. were seen in hospitalized horses at two veterinary hospitals. 76 salmonella strains from hospitalized horses and 18 strains from horses without any clinical contact were characterized by serotyping and plasmid profile analysis. from april 1990 through january 1991 97.8% of the hospitalized horses were infected with strains of s. typhimurium var. copenhagen, which were closely related acc ... | 1992 | 1558527 |
| in vivo administration of bryostatin 1, a protein kinase c activator, decreases murine resistance to salmonella typhimurium. | bryostatin 1, a potent activator of protein kinase c, has antitumor activity against murine lymphoma, leukemia, and melanoma. in vitro, this compound stimulates the release of gamma-interferon, interleukins, and hematopoietic growth factors from accessory cells and activates both t- and b-cells. bryostatin 1 is also able to stimulate neutrophils to undergo oxidative burst and degranulation. because of the ability of this compound to stimulate the immune system, cause release of immune mediators, ... | 1992 | 1559218 |
| the flia (rpof) gene of pseudomonas aeruginosa encodes an alternative sigma factor required for flagellin synthesis. | in order to better understand the regulation of pseudomonas aeruginosa flagellin expression we cloned the sigma factor of rna polymerase used to transcribe the flagellin gene. it is a member of the sigma 28 class of alternative sigma factors described in several bacterial genera. using the published sequence of the flia gene encoding the sigma 28 from salmonella typhimurium, we designed two oligonucleotides and, using the polymerase chain reaction, isolated the flia gene from s. typhimurium chro ... | 1992 | 1560774 |
| cloning and sequence of thioredoxin gene of salmonella typhimurium lt2. | 1992 | 1561103 | |
| the effect of air scrubbing on moisture pickup, aerobic plate counts, enterobacteriaceae, and the incidence of salmonellae on artificially inoculated broiler carcasses. | processed broiler carcasses were subjected to diffused air at 158.6 kpa (air scrubbing) in tap water to evaluate the potential of this treatment for improving the microbiological quality of read-to-cook poultry. carcasses were inoculated with a marker strain of salmonella typhimurium 5 min before treatment. the carcasses were removed after 30 min and sampled for aerobic plate counts (apc), enterobacteriaceae (ent) counts, for the presence of the marker organism, or for moisture pickup. the s. ty ... | 1992 | 1561223 |
| the mutagenicity of electrocautery smoke. | careful analysis of electrocautery smoke produced during breast surgery has found organic compounds that are unidentifiable with current analytical techniques. the purpose of this study was to determine the potential mutagenicity of the smoke produced by the electrocautery knife during reduction mammaplasty. multiple air samples were collected in the operating room during two reduction mammaplasty procedures. airborne smoke particles were tested for mutagenic potential in both tester strains of ... | 1992 | 1561248 |
| [rhabdomyolysis associated with salmonella typhimurium infection]. | 1992 | 1561462 | |
| antigenic role of stress-induced catalase of salmonella typhimurium in cell-mediated immunity. | the ability of the h2o2-induced catalase of salmonella typhimurium to induce cell-mediated immunity against s. typhimurium infection in mice was examined. when exponentially growing cells of s. typhimurium were treated with 20 microm h2o2, the cells resisted killing by 1 mm h2o2 and showed the induction of a new species of catalase in addition to the constitutively produced one. two molecules of catalases in s. typhimurium were isolated from mutant strains: h2o2-induced catalase (catalase ii, 32 ... | 1992 | 1563769 |
| bacterial resistance to complement killing mediated by the ail protein of yersinia enterocolitica. | ail is a 17-kda outer membrane yersinia protein that mediates bacterial attachment to, and invasion of, cultured epithelial cells. we report here an alternative role for ail in the pathogenesis of yersinia infection. we found that escherichia coli hb101 harboring the 4-kilobase recombinant ail clone pvm102 were highly resistant to killing in up to 50% normal human serum. a 674-base-pair fragment of dna from pvm102, which encodes the ail gene, was inserted into puc18 and shown to promote full res ... | 1992 | 1565652 |
| effect of feeding selected short-chain fatty acids on the in vivo attachment of salmonella typhimurium in chick ceca. | two groups of 20 chicks each were fed 1% fatty acid continuously starting at 1 day of age, while a control group of 20 chicks received unsupplemented feed. at 2 days of age, chicks were inoculated orally with 1 ml of salmonella typhimurium (1 x 10(6) colony-forming units/ml). ceca were obtained from six chicks of each group at 7, 14, and 21 days of age. at 14 days of age, formic and propionic acids had statistically reduced salmonella recovery by 2.56 logs and 3.09 logs, respectively, compared w ... | 1992 | 1567301 |
| reaction of the avian respiratory system to intratracheally administered avirulent salmonella typhimurium. | chickens were inoculated intratracheally (it) with the sr-11 salmonella typhimurium deletion mutant x4062 strain. data collected for 8 days postinoculation (pi) were: signs of respiratory and gastrointestinal disease; histological lesions; the influx, phagocytic proportion, and phagocytic capacity of avian respiratory phagocytes (arps); and the proportion of granulocytes vs. macrophages in the lung tissues and lavage fluids of the lungs and air sacs. s. typhimurium-inoculated chickens had no cli ... | 1992 | 1567305 |
| allosteric interactions coordinate catalytic activity between successive metabolic enzymes in the tryptophan synthase bienzyme complex. | tryptophan synthase from enteric bacteria is an alpha 2 beta 2 bienzyme complex that catalyzes the final two reactions in the biosynthesis of l-tryptophan (l-trp) from 3-indole-d-glycerol 3'-phosphate (igp) and l-serine (l-ser). the bienzyme complex exhibits reciprocal ligand-mediated allosteric interactions between the heterologous subunits [houben, k., & dunn, m. f. (1990) biochemistry 29, 2421-2429], but the relationship between allostery and catalysis had not been completely defined. we have ... | 1992 | 1567839 |
| structure and function of the uhp genes for the sugar phosphate transport system in escherichia coli and salmonella typhimurium. | expression of the escherichia coli sugar phosphate transport system, encoded by the uhpt gene, is regulated by external glucose 6-phosphate through the action of three linked regulatory genes, uhpabc. the nucleotide sequence of the uhp region cloned from salmonella typhimurium was determined. the deduced uhp polypeptide sequences from the two organisms are highly related. comparison with the corrected sequence from e. coli revealed that the four uhp genes are closely spaced, with minimal interge ... | 1992 | 1569007 |
| promoter elements required for positive control of transcription of the escherichia coli uhpt gene. | the uhpabct locus of escherichia coli encodes the transport system which allows the cell to accumulate a variety of sugar phosphates in unaltered form. the expression of uhpt, the gene encoding the transport protein, is regulated by the uhpabc gene products. the uhpa protein is required for expression; its deduced amino acid sequence shows that it belongs to a subfamily of bacterial transcription regulators including narl, degu, and fixj. members of this subfamily have an amino-terminal phosphor ... | 1992 | 1569008 |
| uv mutagenesis in salmonella typhimurium is umudc dependent despite the presence of samab. | we investigated the role of the umudc and samab operons in the uv mutability of salmonella typhimurium. umudc is located on the chromosome, whereas samab resides on the virulence plasmid pslt. using allele replacement and plasmid curing techniques, we found that uv mutability was eliminated when any of three different umudc alleles (umud1, umuc1, or umud1 umuc1) were on the chromosome even when samab was present. we conclude that samab normally does not complement umudc function in s. typhimuriu ... | 1992 | 1569012 |