| epitope mapping of four monoclonal antibodies recognizing the hexose core domain of salmonella lipopolysaccharide. | four murine monoclonal antibodies reactive with distinctive regions of the hexose core domain of salmonella lipopolysaccharide (lps) were generated and their epitope specificities were delineated. mast 56 (igg1) and mast 50 (igg3) antibodies elicited by immunizations with salmonella typhimurium rb1 and rb2 mutants, reacted selectively in enzyme immunoassay with the lps from rough mutants. in contrast, maty 1 (igm) and maty 2 (igg2b) antibodies raised by an attenuated salmonella typhi 620 ty stra ... | 1991 | 1720777 |
| in vitro effects of l-ascorbic acid (vitamin c) on aryl hydrocarbon hydroxylase activity in hepatic microsomes of mice. | when aromatic hydrocarbon (ah)-responsive and -non-responsive strains of mice were pretreated with 3-methylcholanthrene (mc) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd), vitamin c reduced the microsomal aryl hydrocarbon hydroxylase (ahh) activity. the ahh inhibitors 7,8-benzoflavone (7,8-bf) and 3-methylsulfonyl-3',4,4',5-tetrachlorobiphenyl (3-msf-3',4,4',5-tetracb) showed various inhibitory effects depending upon the types of microsomes, whereas vitamin c exhibited inhibition irrespective of ... | 1991 | 1720872 |
| antimutagenicity of propionic acid bacteria. | the antimutagenic effect of dialysed cell extracts of 4 strains of propionic acid bacteria was examined against the mutagenicity of sodium azide in the ta1535 tester strain of salmonella typhimurium using the ames test. it was noted that dialysates of 2 strains of propionibacterium shermanii, p. pentosaceum and p. acnes, significantly reduced sodium azide-induced revertants. the dialysate of propionic acid cocci did not show an antimutagenic effect. the inhibitory activity was enhanced if the mu ... | 1991 | 1720873 |
| mutagenicity of some heterocyclic amines in salmonella typhimurium with metabolic activation by human red blood cell cytosol. | purified human red blood cell cytosol was used to activate the heterocyclic amines 2-amino-3-methylimidazo[4,5-f]quinoline (iq), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (meiq), 3-amino-1,4-dimethyl-5h-pyrido[4,3-b]indole (trp-p-1) and 3-amino-1-methyl-5h-pyrido[4,3-b]indole (trp-p-2) into mutagenic intermediate(s) in the salmonella test. the liquid preincubation method in the presence of strain ta98 was utilized. in order to understand the mechanism involved in this metabolic activation, som ... | 1991 | 1722281 |
| immunoadjuvant activity of oral lactobacillus casei: influence of dose on the secretory immune response and protective capacity in intestinal infections. | lactobacilli, often used as effectors of host functions, could play an important role in maintaining human health by controlling other intestinal microorganisms capable of producing harmful effects. using an experimental model, we studied the effect of different oral doses of lactobacillus casei on the secretory iga response and the protective capacity of the microorganism in preventing intestinal infections. the optimization of the protective dose of lb. casei by previous feeding and the use of ... | 1991 | 1722492 |
| the sugar-specific outer membrane channel scry contains functional characteristics of general diffusion pores and substrate-specific porins. | escherichia coli k-12 strain ps1-28-37 carries the multicopy plasmid ppso28-37 containing a dna fragment coding for two of the proteins that enable bacteria to utilize sucrose as sole carbon source. one of the different gene products of the plasmid is the outer membrane protein, scry. this protein was isolated and purified by chromatography across a gel filtration column. reconstitution experiments with lipid bilayer membrane demonstrated that scry formed ion-permeable channels with properties v ... | 1991 | 1722560 |
| [dnaase activity, a method of differentiating hospital strains of salmonella typhimurium]. | measurements of dnase activities in salmonella typhimurium strains of various origins have demonstrated that hospital strains are characterized by the highest dnase activity. this activity correlates with the presence of r-plasmids in the cells. high dnase activity of hospital strains is a stable marker, and therefore may be used for intraspecies differentiation of s. typhimurium. | 1991 | 1722855 |
| identification of the main epitope on human cytochrome p450 iid6 recognized by anti-liver kidney microsome antibody. | antibodies present in the sera of a group of children with autoimmune hepatitis react with human cytochrome p450 iid6. cdna constructions of various fragments of human p450 iid6 were made and expressed and the resulting peptides were tested in immunoblot with patients' sera. these allowed identification of at least two antigenic sites on the p450 molecule. the main one, recognized by all sera tested, is located between amino acids 239 and 271. synthesis of three peptides covering this area of th ... | 1991 | 1723273 |
| mutagenicity of 2-methylacrolein, 2-ethylacrolein and 2-propylacrolein in salmonella typhimurium ta100. a comparative study. | the c2-alkylated acrolein derivatives 2-methylacrolein, 2-ethylacrolein and 2-propylacrolein are mutagenic in salmonella typhimurium ta100. they are direct mutagens, their mutagenic potency being inversely proportional to the size of the alkylating substituent in the c2 position. in the presence of s9 mix, the mutagenicity of all these substances is considerably reduced; the reduction in mutagenicity is inversely proportional to the direct mutagenic potential of the substance. as shown for 2-met ... | 1991 | 1723498 |
| repair of cytotoxic lesions induced by n-methyl-n'-nitro-n-nitrosoguanidine in salmonella typhimurium and escherichia coli. | the role of nucleotide excision repair and 3-methyladenine dna glycosylases in removing cytotoxic lesions induced by n-methyl-n'-nitro-n-nitrosoguanidine (mnng) in salmonella typhimurium and escherichia coli cells was examined. compared to the e. coli wild-type strain, the s. typhimurium wild-type strain was more sensitive to the same dose of mnng. nucleotide excision repair in both bacterial species does not contribute significantly to the survival after mnng treatment, indicating that the obse ... | 1991 | 1723500 |
| the influence of the nucleotide excision-repair system on mutagenesis in salmonella typhimurium lt2 after exposure to low doses of monofunctional alkylating agents. | the role of nucleotide excision repair in the mutagenicity of the monofunctional alkylating agents n-methyl-n'-nitro-n-nitrosoguanidine (mnng), methyl methanesulfonate (mms), n-ethyl-n'-nitro-n-nitrosoguanidine (enng), and n-ethyl-n-nitrosourea (enu) in salmonella typhimurium was examined. the mutagenic potential of the mutagenic agents used increased in the following order: mms less than enu less than enng less than mnng. the results obtained confirm the involvement of nucleotide excision repai ... | 1991 | 1723501 |
| [the serologic diagnosis of group b salmonelloses]. | antibacterial sera activities towards citrobacter o22 and salmonella typhimurium were tested with o22, o1, o4, o5, o12 erythrocytic diagnostic agents. cross activities of o22, o1, o4, o5, o12, and hi antigens were tested with the same and hi erythrocytic diagnostic agents in the antibody neutralization test. the findings have confirmed the identity or very close relationship between the tested o antigens. screening for antigens of the excretions from patients with s. typhimurium and citrobacter ... | 1991 | 1724040 |
| impaired bactericidal activity of serum of a child suffering from focal proliferative glomerulonephritis. | the serum of a child with focal proliferative glomerulonephritis was found to exhibit a weaker bactericidal activity against pseudomonas aeruginosa, salmonella typhimurium, salmonella enteritidis and escherichia coli strains as compared with sera of the child's parents. the child's serum showed a low haemolytical activity of complement as well as a low c3 concentration. the authors believe that the abnormal complement concentration could cause the impaired bactericidal activity of the patient se ... | 1991 | 1725093 |
| decontamination of aqueous solutions of biological stains. | aqueous solutions of a number of biological stains were completely decontaminated to the limit of detection using amberlite resins. amberlite xad-16 was the most generally applicable resin but amberlite xad-2, amberlite xad-4, and amberlite xad-7 could be used to decontaminate some solutions. solutions of acridine orange, alcian blue 8gx, alizarin red s, azure a, azure b, congo red, cresyl violet acetate, crystal violet, eosin b, erythrosin b, ethidium bromide, janus green b, methylene blue, neu ... | 1991 | 1725856 |
| biological activity of novel macrocyclic alkaloids (budmunchiamines) from albizia amara detected on the basis of interaction with dna. | extracts derived from albizia amara were found to demonstrate activity in a recently developed hplc system designed to detect compounds capable of interacting with dna. further investigation led to the procurement of four sets of alkaloid isolates x1-x4 that were found to be macrocyclic pithecolobine alkaloids. all four isolates interacted with calf thymus dna and were generally cytotoxic with a battery of cultured mammalian cells. as determined with salmonella typhimurium strain tm677, isolates ... | 1991 | 1725878 |
| colicin e1 export in salmonella typhimurium wild-type and lipopolysaccharide mutants. | colicin export was studied in different salmonella typhimurium strains lacking the o-antigen repeating units (o-) and different strains with different chemotypes for the lipopolysaccharide core, as well as the wild-type strain (o+), to determine the role of lipopolysaccharide length on colicin e1 export. while the lipopolysaccharide length influences the levels of external hemolytic activity in s. typhimurium, no effect was detected on colicin e1 export. | 1991 | 1726793 |
| the cobii and cobiii regions of the cobalamin (vitamin b12) biosynthetic operon of salmonella typhimurium. | a detailed deletion map of the cobii and cobiii regions of the cobalamin biosynthetic (cob) operon of salmonella typhimurium lt2 has been constructed. the cobii region encodes functions needed for the synthesis of lower ligand 5,6-dimethylbenzimidazole (dmb); cobiii encodes functions needed for the synthesis of the nucleotide loop that joins dmb to the corrin macrocycle. the genetic analysis of 117 deletion, insertion, and point mutations indicates that (i) the cobii and cobiii mutations are con ... | 1992 | 1729212 |
| the salmonella typhimurium virulence plasmid complement resistance gene rck is homologous to a family of virulence-related outer membrane protein genes, including pagc and ail. | a fragment of the salmonella typhimurium virulence plasmid containing the rck locus, when cloned in the recombinant cosmid pade016, was shown previously to confer high-level complement resistance on both rough and smooth escherichia coli, salmonella minnesota, and s. typhimurium and was associated with the production of an outer membrane protein. we determined the nucleotide sequence of the fragment containing the rck locus. mutations in the two major open reading frames confirmed that the compl ... | 1992 | 1729227 |
| distribution of an l-isoaspartyl protein methyltransferase in eubacteria. | a protein carboxyl methyltransferase (ec 2.1.1.77) that recognizes age-damaged proteins for potential repair or degradation reactions has been found in all vertebrate tissues and cells examined to date. this enzyme catalyzes the transfer of methyl groups from s-adenosylmethionine to the carboxyl groups of d-aspartyl or l-isoaspartyl residues that are formed spontaneously from normal l-aspartyl and l-asparaginyl residues. a similar methyltransferase has been found in two bacterial species, escher ... | 1992 | 1729230 |
| regulation of the salmonella typhimurium meta gene by the metr protein and homocysteine. | the dna sequence of the salmonella typhimurium meta control region is presented. s1 nuclease mapping was used to determine the transcription initiation site. by measuring beta-galactosidase levels in escherichia coli strains lysogenized with lambda phage carrying a meta-lacz gene fusion, the metr protein was shown to activate the meta gene. homocysteine, an intermediate in methionine biosynthesis, plays a negative role in the metr-mediated activation mechanism. gel mobility shift assays and dnas ... | 1992 | 1729233 |
| molecular analysis of the escherichia coli phop-phoq operon. | the phop-phoq operon of salmonella typhimurium is a member of the family of two-component regulatory systems and controls expression of the phon gene that codes for nonspecific acid phosphatase and the genes involved in the pathogenicity of the bacterium. the phop-phoq operon of escherichia coli was cloned on a plasmid vector by complementation of a phop mutant, and the 4.1-kb nucleotide sequence, which includes the phop-phoq operon and its flanking regions, was determined. the phop-phoq operon ... | 1992 | 1729240 |
| fumarate or a fumarate metabolite restores switching ability to rotating flagella of bacterial envelopes. | flagella of cytoplasm-free envelopes of escherichia coli or salmonella typhimurium can rotate in either the counterclockwise or clockwise direction, but they never switch from one direction of rotation to another. exogenous fumarate, in the intracellular presence of the chemotaxis protein chey, restored switching ability to envelopes, with a concomitant increase in clockwise rotation. an increase in clockwise rotation was also observed after fumarate was added to partially lysed cells of e. coli ... | 1992 | 1729255 |
| completion of the nucleotide sequence of the 'maltose b' region in salmonella typhimurium: the high conservation of the malm gene suggests a selected physiological role for its product. | we have subcloned and sequenced the genes malf and malm of salmonella typhimurium, thereby completing the determination of the nucleotide sequence of its 'maltose b' regulon. the malm gene, encoding a periplasmic protein of unknown function in escherichia coli, is a highly conserved as genes encoding proteins of known function from the same region. | 1992 | 1730061 |
| the nucleotide sequence of leub from salmonella typhimurium. | the nucleotide sequence and deduced polypeptide sequence of the salmonella typhimurium leub are reported, as well as a conserved region that might bind the enzyme substrate. | 1992 | 1730062 |
| the effect of ellagic acid on xenobiotic metabolism by cytochrome p-450iie1 and nitrosodimethylamine mutagenicity. | ellagic acid (ea) is an inhibitor of the in vitro mutagenicity of n-nitrosodimethylamine (ndma) in salmonella typhimurium strain ta100 using pyrazole-induced rat liver 9000 x g supernatant (s-9). in order to understand this activity, the effect of ea on the metabolic hydroxylation of 4-nitrophenol, a substrate, as is ndma, for cytochrome p-450iie1 was studied using pyrazole induced rat s-9 and microsomal protein. it is shown that ea has an inhibitory effect on 4-nitrophenol hydroxylase with both ... | 1992 | 1730135 |
| role of gamma interferon and tumor necrosis factor alpha in resistance to salmonella typhimurium infection. | in mice infected with a sublethal dose of salmonella typhimurium, the injection of an anti-gamma interferon (ifn-gamma) monoclonal antibody increased bacterial proliferation in the spleen and led to death on day 7 or 8. depletion of both cd4+ and cd8+ t cells with monoclonal antibodies in vivo had a much less marked effect during the first week of infection than the administration of anti-ifn-gamma antibodies, suggesting that cells other than t lymphocytes participate in the production of ifn-ga ... | 1992 | 1730475 |
| enhancement of mucosal antibody responses to salmonella typhimurium and the microbial hapten phosphorylcholine in mice with x-linked immunodeficiency by b-cell precursors from the peritoneal cavity. | the observation that approximately half of the b cells in the murine intestinal lamina propria are derived from peritoneal cd5 b-cell precursors raises the question of their contribution to mucosal protection. using mice with x-linked immunodeficiency which are deficient in cd5+ b cells, we showed that they mount little serum and virtually no intestinal immunoglobulin m (igm), igg, and iga antibody responses following oral inoculation with live salmonella typhimurium. nonresponsive xid mice were ... | 1992 | 1730482 |
| bactericidal activity of c9-deficient human serum. | escherichia coli b/sm, strain 1-1, was killed dose dependently by human hereditary c9-deficient serum (c9dhs), which was shown to contain no c9 ag by an elisa method. on the other hand, human hereditary c7-deficient serum did not kill the bacteria under similar conditions. the bactericidal activity of c9dhs was inhibited by rabbit anti-c5 antibody but not by murine anti-c9 mab. the anti-c9 antibody decreased the bactericidal activity of normal human serum (nhs) to the level of that with c9dhs. s ... | 1992 | 1730876 |
| direct-acting mutagenic activity in white, rosé, and red wines with the ara test of salmonella typhimurium. | thirty-two commercially produced white, rosé, and red wines from spain were assayed for genotoxicity. the ara forward mutagenicity assay with salmonella typhimurium served as the test system. all the wines were mutagenic in the absence of mammalian microsomal activation (s9 mix) and/or glycosidase activities with the exception of one rosé wine which gave a clear dose-response relationship, although its mutagenic potency was considered statistically nonsignificant. the mutagenic activity covered ... | 1992 | 1732101 |
| a qsar investigation of the role of hydrophobicity in regulating mutagenicity in the ames test: 1. mutagenicity of aromatic and heteroaromatic amines in salmonella typhimurium ta98 and ta100. | quantitative structure-activity relationships (qsar) have been derived for the mutagenic activity of 88 aromatic and heteroaromatic amines acting on salmonella typhimurium ta98 + s9 and 67 amines acting on ta100 + s9. mutagenic activity is linearly dependent on hydrophobicity, the energy of the highest occupied molecular orbital, and the energy of the lowest unoccupied molecular orbital of the amine. the dependence of mutagenic activity on hydrophobicity and electronic effects is nearly identica ... | 1992 | 1732103 |
| quantitative structure-activity relationship investigation of the role of hydrophobicity in regulating mutagenicity in the ames test: 2. mutagenicity of aromatic and heteroaromatic nitro compounds in salmonella typhimurium ta100. | a quantitative structure-activity relationship (qsar) has been derived for the mutagenic activity of 117 aromatic and heteroaromatic nitro compounds acting on salmonella typhimurium ta100. relative mutagenic activity is bilin-early dependent on hydrophobicity, with an optimal log p of 5.44, and is linearly dependent on the energy of the lowest unoccupied molecular orbital of the nitro compound. the dependence of mutagenic activity on hydrophobicity and electronic effects is very similar for ta98 ... | 1992 | 1732104 |
| in vivo genotoxicity studies with p-benzoquinone dioxime. | p-benzoquinone dioxime (bqd) appears to be a sex-specific rat carcinogen inducing tumours of the urinary bladder in female rats. the present paper shows that bqd is a direct-acting mutagen in salmonella typhimurium ta98, confirming published data. in contrast to this in vitro data, negative results were obtained after oral administration of bqd to female rats in both the bone marrow micronucleus test and the in vivo liver uds test. bqd did, however, induce a marked effect upon s-phase synthesis ... | 1992 | 1732106 |
| molecular analysis of the flagellar switch protein flim of salmonella typhimurium. | defects in the chemotaxis proteins chey and chez of salmonella typhimurium can be suppressed by mutations in the flagellar switch, such that swarming of a pseudorevertant on semisolid plates is significantly better than that of its parent. chey suppressors contribute to a clockwise switch bias, and chez suppressors contribute to a counterclockwise bias. among the three known switch genes, flim contributes most examples of such suppressor mutations. we have investigated the changes in flim that a ... | 1992 | 1732214 |
| identification and sequences of the lipopolysaccharide core biosynthetic genes rfaq, rfap, and rfag of escherichia coli k-12. | the rfa locus of escherichia coli k-12 includes a block of about 10 closely spaced genes transcribed in the same direction which are involved in synthesis and modification of the hexose region of the lipopolysaccharide core. we have sequenced the first three genes in this block. the function of the first of these genes is unknown, but we have designated it rfaq on the basis of its location and similarity to other rfa genes. complementation of salmonella typhimurium rfa mutants with e. coli rfa r ... | 1992 | 1732225 |
| topology of the hydrophobic membrane-bound components of the histidine periplasmic permease. comparison with other members of the family. | the membrane-bound complex of periplasmic permeases comprises two hydrophobic proteins which have been hypothesized to be integral membrane-spaninning proteins. we have investigated the topological organization of the hydrophobic components of the salmonella typhimurium histidine permease, hisq and hism. both proteins are digested by trypsin and proteinase k when either inside-out or right-side-out membrane vesicles are used. therefore, these proteins are exposed to both surfaces of the membrane ... | 1992 | 1733937 |
| correlation between phosphorylation of the chemotaxis protein chey and its activity at the flagellar motor. | phosphorylation of the chemotaxis protein chey by its kinase chea appears to play a central role in the process of signal transduction in bacterial chemotaxis. it is presumed that the role is activation of chey which results in clockwise (cw) flagellar rotation. the aim of this study was to determine whether this activity of chey indeed depends on the protein being phosphorylated. since the phosphorylation of chey can be detected only in vitro, we studied the ability of chey to cause cw rotation ... | 1992 | 1737035 |
| expression of human il-1 beta in salmonella typhimurium. a model system for the delivery of recombinant therapeutic proteins in vivo. | the feasibility of using salmonella typhimurium aroa mutant (sl3261) to deliver protein therapeutic agents was investigated in a murine model system. we have constructed an escherichia coli expression plasmid designed to express the human protein il-1 beta. this plasmid expresses il-1 beta to high levels (greater than 30% total cell protein) in e. coli. in salmonella the il-1 beta is expressed constitutively to about 10% total cell protein, as verified by western blotting analysis using polyclon ... | 1992 | 1737934 |
| membrane topology of the integral membrane components, oppb and oppc, of the oligopeptide permease of salmonella typhimurium. | the oligopeptide permease of salmonella typhimurium is a periplasmic binding protein-dependent transport system. five gene products, oppabcdf, are required for the functioning of this transporter, two of which (oppb and oppc) are highly hydrophobic, integral membrane proteins and are responsible for mediating passage of peptides across the cytoplasmic membrane. oppb and oppc are each predicted, from their sequences, to span the membrane many times. in this paper we describe experimental evidence ... | 1992 | 1738314 |
| salmonella bacteraemia in england and wales, 1981-1990. | to report the incidence of nontyphoidal salmonellas in england and wales and identified in the division of enteric pathogens, london between 1981 and 1990. | 1992 | 1740511 |
| control of large chromosomal duplications in escherichia coli by the mismatch repair system. | excessive recombination between repeated, interspersed, and diverged dna sequences is a potential source of genomic instability. we have investigated the possibility that a mechanism exists to suppress genetic exchange between these quasi-homologous (homeologous) sequences. we examined the role of the general mismatch repair system of escherichia coli because previous work has shown that the mismatch repair pathway functions as a barrier to interspecies recombination between e. coli and salmonel ... | 1991 | 1743481 |
| dna binding, adduct characterisation and metabolic activation of aflatoxin b1 catalysed by isolated rat liver parenchymal, kupffer and endothelial cells. | in vitro studies with rat liver parenchymal, kupffer and endothelial cells isolated from male sprague-dawley rats were undertaken to investigate cell-specific bioactivation of aflatoxin b1, dna binding and adduct formation. in the mutagenicity studies, using homogenates of all three separated liver cell populations (co-incubated with nadp+ and glucose-6-phosphate as cofactors for the cytochrome p-450 monooxygenase system) parenchymal, kupffer and endothelial cells were able to activate aflatoxin ... | 1991 | 1747061 |
| evaluation of the in vivo genotoxicity of the structural analogues 2,6-diaminotoluene and 2,4-diaminotoluene using the rat micronucleus test and rat liver uds assay. | the two structural isomers 2,4- and 2,6-diaminotoluene (dat) differ in their carcinogenic properties; the 2,4-isomer is carcinogenic in rats and mice, whereas the 2,6-isomer has been reported to be non-carcinogenic. both isomers were reported to be mutagenic in salmonella typhimurium in the presence of s9, which was confirmed in the present study before in vivo assays were commenced. both isomers were tested in the rat bone marrow micronucleus test and the rat liver uds test to investigate how w ... | 1991 | 1747922 |
| formation of a glutathione conjugate and a semistable transportable glucuronide conjugate of n2-oxidized species of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) in rat liver. | we have previously shown that 2-hydroxamino-1-methyl-6-phenylimidazo[4,5-b]pyridine(2-h ydroxamino-phip) is the principal metabolite leading to mutations in salmonella typhimurium ta98 and dna damage in mammalian cells. in rat hepatocytes this metabolite can be further conjugated to 2-(n-beta-d-glucuronopyranosyl (hydroxamino)-1-methyl-6-phenylimidazo[4, 5-b]pyridine[n(oh)-gluc-phip]. its rate of formation was increased in hepatocytes from polychlorinated biphenyl (pcb)-pretreated animals. this ... | 1991 | 1747923 |
| molecular mimickry between hla b27 and yersinia, salmonella, shigella and klebsiella within the same region of hla alpha 1-helix. | two new examples of amino acid homology between hla b27 and microbes triggering hla b27-associated diseases are described. an outer membrane protein yada (yersinia adhesin, previously called yop1) of yersinia enterocolitica and y. pseudotuberculosis shares a linear tetrapeptide with hla b27. a cationic outer membrane protein omph of salmonella typhimurium shares homology with five amino acids of hla b27 in a non-linear fashion. the four amino acids of yada are also notably included in the hexape ... | 1991 | 1747948 |
| analysis of salmonella typhimurium hisd3052 revertants: the use of oligodeoxyribonucleotide colony hybridization, pcr, and direct sequencing in mutational analysis. | a rapid method for determining the dna sequences of salmonella typhimurium hisd3052 revertants is presented. dna colony hybridization was used to analyze revertants previously studied by isono and yourno [proc natl acad sci usa 71:1612-1617, 1974]. synthetic oligodeoxyribonucleotide probes (18-mers) were able to distinguish sequences that differed by a single base pair. mutant his sequences not identified by probing analysis were amplified using polymerase chain reaction (pcr) and directly seque ... | 1991 | 1748083 |
| crystal structure of the lysine-, arginine-, ornithine-binding protein (lao) from salmonella typhimurium at 2.7-a resolution. | a wide variety of sugars, amino acids, peptides, and inorganic ions are transported into bacteria by periplasmic transport systems consisting of substrate-specific receptors (binding proteins) and membrane-bound protein complexes. the crystal structure of the lysine-, arginine-, ornithine-binding protein (lao) at 2.7-a resolution shows that the molecule has a bi-lobal structure and that its topological structure is different from other amino acid-binding proteins but is similar to the sulfate-bi ... | 1991 | 1748660 |
| in vitro characterization of intra-generic inhibition of growth in salmonella typhimurium. | the intra-generic inhibition of bacterial growth observed previously in vivo and in vitro with strains of salmonella, citrobacter and e. coli was studied in vitro using s. typhimurium strain f98. there was complete inhibition of multiplication of s. typhimurium when it was added to stationary-phase broth cultures of different salmonella serotypes, but only partial inhibition when added to broth cultures of e. coli. the degree of inhibition between different mutants of f98 was affected by the num ... | 1991 | 1748870 |
| case report: salmonellosis complicated by leukocytoclastic vasculitis. | we report the case of a healthy young hispanic man with salmonella typhimurium bacteremia and leukocytoclastic vasculitis. leukocytoclastic vasculitis has not been previously reported as a complication of salmonella gastroenteritis and bacteremia. salmonella gastroenteritis is rarely associated with bacteremia in healthy young adults. | 1991 | 1750449 |
| a cluster of genes that affects nucleoid segregation in salmonella typhimurium. | thirteen conditional lethal mutations in genes of salmonella typhimurium map at the clmf locus and affect both viability and the faithful partitioning of daughter nucleoids. these mutations have now been divided into three complementation groups by using cloned fragments of s. typhimurium dna and renamed parc, pare, and parf. the proteins produced from the cloned fragments predict that parc is an 85-kd protein, pare is 75 kd in size, and parf, 27 kd. the pare gene is about 5 kb upstream of the p ... | 1991 | 1751451 |
| the epidemiology of salmonella in calves: the role of markets and vehicles. | environmental contamination has been shown to be an important aspect of the epidemiology of salmonellosis in calves. markets and transport vehicles are important links in the calf marketing chain and these were investigated to determine the level of salmonella contamination. salmonellas were isolated from 7 of the 14 markets surveyed, with 31 of 838 samples (3.7%) being positive. nine different salmonella serotypes, of which the commonest was salmonella typhimurium, were isolated. four different ... | 1991 | 1752301 |
| invasion of hep-2 cells by strains of salmonella typhimurium of different virulence in relation to gastroenteritis. | experiments to measure the invasiveness of seven strains of salmonella typhimurium for hep-2 cells showed that high inocula (100 bacteria/hep-2 cell), as used by most workers to synchronise events and to increase the number of bacteria which invade, resulted in recovery of significantly less than 1% of the original inoculum after treatment with gentamicin to kill extracellular bacteria. also, the cell culture medium became acidic, and microscopic examination of giemsa-stained monolayers immediat ... | 1991 | 1753393 |
| methods for inoculation and recovery of salmonella from chicken eggs. | various methods of applying inoculum and recovering low numbers of artificially inoculated salmonella typhimurium on eggs were evaluated. inoculation methods tested were suspending cells in 1) .85% saline; 2) 1% peptone; 3) sterile chicken fecal paste; or 4) a 1:10 dilution of chicken feces in .85% saline. sampling methods tested were 1) shell and membrane massage; and 2) mortar and pestle grinding of shells and membranes. the method that yielded the best recovery of low numbers of salmonella wa ... | 1991 | 1754543 |
| mutagenicity studies of kojic acid. | kojic acid, a fungal metabolite produced by some species of aspergillus and penicillium, was found to induce sister chromatid exchanges and chromosomal aberrations in chinese hamster ovary cells in the presence or absence of the rat liver s9 mix. furthermore, this compound was demonstrated to induce mutations in salmonella typhimurium strains ta98 and ta100 using both plate-incorporation and preincubation methods. | 1991 | 1755028 |
| benzo[e]pyrene pretreatment of immature, female c57bl/6j mice results in increased bioactivation of aflatoxin b1 in vitro. | hepatic microsomes were prepared from immature c57bl/6j mice 24 h after receiving intraperitoneal injections of either corn oil, benzo[e]pyrene (bep, 50 mg/kg) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd, 4 x 10(-3) mg/kg). the capacity of these hepatic microsomes to bioactivate aflatoxin b1 (afb1), 2-aminoanthracene (aa), benzo[a]pyrene (bap), 3-methylcholanthrene (mc), 7,12-dimethylbenzanthracene (dmba), bep and pyrene (py) was measured using strain ta100 in the salmonella typhimurium/microso ... | 1991 | 1755035 |
| cloning and sequence analysis of hydrogenase regulatory genes (hydhg) from salmonella typhimurium. | the nucleotide sequence of the hydhg operon, comprised of chromosomal genes that regulate labile hydrogenase activity in salmonella typhimurium, was compared with the reported hydhg sequence of escherichia coli. nucleotide sequence analysis of a 4.8 kb ecori fragment of salmonella chromosomal dna revealed that one of the open reading frames (orf) encoded a protein of 441 amino acid residues. this large orf was identified on a 2.7 kb eco ri/hindiii fragment and coded for the complete hydg gene. t ... | 1991 | 1756170 |
| [an experimental study of a lactoglobulin preparation against opportunistic bacteria and salmonellae]. | a preclinical study of seven batches of lactoglobulin, a new biological preparation against opportunistic bacteria and salmonellae, has been carried out. high antibacterial activity of the preparation with respect to the virulent forms of salmonella typhimurium, salmonella enteritidis, pseudomonas aeruginosa, klebsiella pneumoniae, proteus vulgaris, proteus mirabilis has been established. the preparation has been shown to be safe and nontoxic. the 4-year term of its storage at a temperature of 6 ... | 1991 | 1759523 |
| effect of emodin on cooked-food mutagen activation. | the herbs rheum palmatum b and polygonum cuspidatum s are frequently used as laxatives and anticancer drugs in chinese medicine. the antimutagenic activity of these herbs as well as their active component emodin was examined in salmonella typhimurium ta98. the crude extracts and emodin induced a dose-dependent decrease in the mutagenicity of benzo[a]pyrene (b[a]p), 2-amino-3-methylimidazo[4,5-f]quinoline (iq) and 3-amino-1-methyl-5h-pyrido[4,3-b]indole (trp-p-2). furthermore, emodin reduced the ... | 1991 | 1761256 |
| intracellular replication is essential for the virulence of salmonella typhimurium. | salmonella typhimurium is a facultative intracellular parasite, capable of penetrating, surviving, and multiplying within diverse eukaryotic cell types, including epithelial and phagocytic cells. we have been studying intracellular replication of s. typhimurium and found that it is essential in the pathogenesis of this bacterium. a total of 45,000 independent mini-mu mudj transposon mutants in s. typhimurium sl1344 were screened in madin-darby canine kidney (mdck) epithelial cells with a beta-la ... | 1991 | 1763061 |
| epidemiology of salmonella typhimurium infection in calves: persistence of salmonellae on calf units. | salmonella typhimurium dt204c infection is the commonest cause of salmonellosis in calves. on five calf rearing farms a distinct strain, as indicated by plasmid profile analysis, was found to have persisted on the premises for periods ranging from four months to two years, the average being 14 months. the persistence of salmonellae in the environment appears to be an important factor in the epidemiology of calf salmonellosis and clearly indicates the inadequacy of many cleaning and disinfection ... | 1991 | 1763466 |
| studies on the mutagenicity of hair dyes made in china. | a total of 13 commercial hair dye products made in china were tested for mutagenicity in 2 short-term bioassays, the histidine-requiring mutants of salmonella typhimurium (strains ta98 and ta100) and the micronucleus test with mouse bone-marrow polychromatic erythrocyte cells in vivo. the results showed that the 13 hair dyes were not mutagenic in strains ta98 and ta100 with and without s-9. in the micronucleus test, no mutagenic effect was observed. | 1991 | 1764222 |
| mutagenic activities of tryptophan metabolites before and after nitrite treatment. | the mutagenic activities of 16 kinds of tryptophan metabolites, before and after nitrite treatment, were examined in the ames test. none of the compounds showed mutagenic activity before nitrite treatment. after nitrite treatment under acidic conditions, 11 compounds showed mutagenic activity towards salmonella typhimurium ta100 strain in the absence of a metabolic activation system. tryptophan induced 1000 revertant colonies/mumol, while 5-hydroxyindole, 5-hydroxytryptamine and 3-hydroxykynuren ... | 1991 | 1765329 |
| a bacillus subtilis dipeptide transport system expressed early during sporulation. | two previously identified bacillus subtilis dna segments, dcia and dcib, whose transcripts accumulate very rapidly after induction of sporulation, were found in the same 6.2 kb transcription unit, now known as the dcia operon. analysis of the sequence of the dcia operon showed that its putative products are homologous to bacterial peptide transport systems. the product of the fifth gene, dciae, is similar to peptide-binding proteins from escherichia coli and salmonella typhimurium (dppa and oppa ... | 1991 | 1766370 |
| phop/phoq: macrophage-specific modulators of salmonella virulence? | the regulation of gene expression by the two-component regulatory system phop/phoq is necessary for salmonella typhimurium survival within macrophages, defensin resistance, acid resistance, and murine typhoid fever pathogenesis. salmonella experience multiple environments during mammalian infection and survival requires tightly regulated gene expression. after phagocytosis by macrophages, signal transduction by phoq results in the transcription of phop-activated genes (pags) encoding proteins es ... | 1991 | 1766380 |
| cloning of a sequence of aquaspirillum magnetotacticum that complements the arod gene of escherichia coli. | a 2 kb dna fragment isolated from a cosmid library of aquaspirillum magnetotacticum strain ms-1 complements the aromatic-metabolite requirements and iron-uptake deficiencies of escherichia coli and salmonella typhimurium strains that lack a functional arod (biosynthetic dehydrodquinase) sequence. all recombinant cosmids selected for their arod complementation property carry this sequence. no dna sequence homology has, however, been detected by southern hybridization between the cloned fragment a ... | 1991 | 1766390 |
| light sensitivity of methanogenic archaebacteria. | representatives of four families of methanogenic archaebacteria (archaea), methanobacterium thermoautotrophicum delta h, methanobacterium thermoautotrophicum marburg, methanosarcina acetivorans, methanococcus voltae, and methanomicrobium mobile, were found to be light sensitive. the facultative anaerobic eubacteria escherichia coli and salmonella typhimurium, however, were tolerant of light when grown anaerobically under identical light conditions. interference filters were used to show that gro ... | 1991 | 1768142 |
| isolation and characterization of bacteriophage fc3-10 from klebsiella spp. | fc3-10 is a klebsiella spp. specific bacteriophage isolated on a rough mutant (strain kt707, chemotype rd) of k. pneumoniae c3. the bacteriophage receptor for this phage was shown to be the low-molecular mass lipopolysaccharide (lps) fraction (lps-core oligosaccharides), specifically the heptose content of the lps inner-core. this is the first phage isolated on klebsiella, the receptor for which is the lps-core. this phage was unable to plate on salmonella typhimurium lps mutants with chemotypes ... | 1991 | 1769536 |
| mutagenic activity of south indian food items. | dietary components and food dishes commonly consumed in south india were screened for their mutagenic activity. kesari powder, calamus oil, palm drink, toddy and kewra essence were found to be strongly mutagenic; garlic, palm oil, arrack, onion and pyrolysed portions of bread toast, chicory powder were weakly mutagenic, while tamarind and turmeric were not. certain salted, sundried and oil fried food items were also mutagenic. cissus quadrangularis was mutagenic, while 'decoctions' of cumin seed ... | 1991 | 1769715 |
| delayed-type hypersensitivity antigens detected in culture supernatants of salmonella typhimurium. | protein antigens eliciting delayed type hypersensitivity (dth) were analyzed and purified from the supernatants of protein-free cultures in which salmonella typhimurium tv148 organisms had grown. dth activity was measured by the footpad swelling test in mice immunized with living organisms of s. typhimurium tv148 or escherichia coli k-12. dth activity in the culture supernatant was specific to tv148-immunized mice. this activity was destroyed by pronase. dth activity was unable to pass through a ... | 1991 | 1769745 |
| purification and properties of cloned salmonella typhimurium lt2 sialidase with virus-typical kinetic preference for sialyl alpha 2----3 linkages. | subclones containing the salmonella typhimurium lt2 sialidase gene, nanh, were expressed in escherichia coli from multicopy derivatives of pbr329. the cloned sialidase structural gene directed overproduction of sialidase polypeptide which was detected as the major soluble protein species in cell-free extracts. overproduced enzyme was purified to near electrophoretic homogeneity after 65-fold enrichment using conventional preparative techniques. unlike all previously investigated sialidases, s. t ... | 1991 | 1769974 |
| [toxicology of acetonitrile]. | acetonitrile is a high-polarity organic solvent widely used in various chemical industries and laboratories. it was once used in consumer goods such as cosmetics. acetonitrile is readily absorbed through the skin, by inhalation and by ingestion, and acute poisoning and even fatal effects are possible via these routes. the oral ld50 of acetonitrile in mice, which are one of the most susceptible animals to acetonitrile, is 170-520 mg/kg, and lc50 is about 2,700 ppm after one hour of inhalation. th ... | 1991 | 1770614 |
| [the co-mutagenic effect of metabolic extracts of fungi grown on the main grain in high incidence liver cancer areas--fusui county]. | twenty strains of the common fungi were isolated from the staple grains in the high incidence liver cancer areas--fusui county, and their metabolic extracts were prepared. possible co-mutagenic effects of these metabolic extracts on salmonella typhimurium ta98 and ta100 mutants were tested. the results showed that in vitro these metabolic extracts had different degrees of co-mutagenic effects. it is considered that these co-mutagenic effects may play an important role in the incidence of liver c ... | 1991 | 1773673 |
| [plasmid psk1002-mediated mutator effect and sos response in salmonella typhimurium and its use for detection of mutagens]. | the plasmid psk1002 carrying the fused gene umuc'-'lacz could increase the number of revertants induced by methyl methanesulfonate (mms) and 4-nitroquinoline-1-oxide (4nqo) in s. typhimurium lt2 ta 1535(his-). maximum revertants were 4.35 and 3.96 times that of the controls without the plasmid. the values induced by n-methyl-n'-nitrosoquanidine (mn-ng) were about the same with or without plasmid. however, the plasmid pkm101-mediated mutagenesis-enhancing effect was much greater than that through ... | 1991 | 1773674 |
| characterization of murine monoclonal antibodies against serogroup b salmonellae and application as serotyping reagents. | six murine hybridoma monoclonal antibodies reactive with lipopolysaccharide antigens of salmonella typhimurium were obtained from a fusion of immune spleen cells from mice immunized with s. typhimurium and ns1 myeloma cells. four antibodies appeared to be specific for serogroup b salmonellae, while the remaining two antibodies were found to be cross-reactive with salmonella paratyphi a. the exquisite specificities of the salmonella serogroup b monoclonal antibodies were demonstrated by their uni ... | 1991 | 1774314 |
| brain abscess caused by salmonella typhimurium. case report and review of the literature. | brain abscess due to salmonella species are very rare. in this paper a case of brain abscess caused by salmonella typhimurium is reported. the patient had no history of salmonellosis. a review of the literature is also presented. | 1991 | 1774598 |
| purified nad(p)h-quinone oxidoreductase enhances the mutagenicity of dinitropyrenes in vitro. | the effect of highly purified rat liver cytosolic nad(p)h-quinone oxidoreductase [ec 1.6.99.2] on the mutagenicity of 1,3- 1,6- and 1,8-dinitropyrene (dnp) was studied in the ames salmonella typhimurium mutagenicity assay. nad(p)h-quinone oxidoreductase over the range of 0.02-0.8 micrograms/plate (38-1500) units increased up to threefold the mutagenicity of all three dnps in s. typhimurium ta 98. in ta98nr, a strain deficient in "classical" nitro-reductase, the mutagenicity of 1,6- and 1,8-dnp w ... | 1991 | 1774770 |
| distribution of oxytetracycline to tissue cages and granuloma pouches in calves and effect of acute inflammation on distribution to tissue cages. | the effect of acute inflammation on oxytetracycline (otc) distribution was studied in a tissue cage model in calves. an acute inflammatory reaction was induced in tissue cages by injecting lipopolysaccharide (lps) from salmonella typhimurium. the distribution of otc to tissue cage fluid (tcf) was also compared with distribution to fluid from granuloma pouches (gpf). tissue from lps-injected cages showed histological changes indicating an acute inflammatory reaction. concentrations of otc were hi ... | 1991 | 1774815 |
| biological effects of veillonella parvula and bacteroides intermedius lipopolysaccharides. | a comparative study on the endotoxic effects of lipopolysaccharide (lps) from veillonella parvula atcc 10790 and from bacteroides intermedius bmh was performed using an in vivo approach in the c57bl/6 mouse. phenol-water extracted lps of such anaerobes was purified by ultracentrifugation and dnase/rnase digestion, and characterized by a metachromatic assay for endotoxins and by electrophoresis on sds-polyacrylamide gel and silver staining. mouse ld50 for v. parvula lps was 1.479 mg and for b. in ... | 1991 | 1775087 |
| role of ring oxidation in the metabolic activation of 1-nitropyrene. | nitrated polycyclic aromatic hydrocarbons are wide-spread environmental pollutants that have been detected in photocopier toners, airborne particulates, coal fly ash, and diesel engine exhaust emissions. 1-nitropyrene, a representative nitropolycyclic aromatic hydrocarbon present in diesel particulates, is a mutagen in salmonella typhimurium and a tumorigen in laboratory animals. the activation of 1-nitropyrene to a bacterial mutagen has been attributed to nitroreduction; however, the metabolic ... | 1991 | 1777157 |
| the influence of lactobacillus plantarum culture inoculation on the fate of staphylococcus aureus and salmonella typhimurium in montasio cheese. | the growth and survival of staphylococcus aureus and salmonella typhimurium were investigated during the manufacturing and ripening of raw milk montasio cheese. initial inoculated populations in the cheese milk were about 10(5) cfu/ml for s. aureus and 10(6) cfu/ml for s. typhimurium. samples of curds and cheeses were taken during manufacturing and storage and analysed for ph and microbial populations. s. aureus increased slightly in number during the early period of ripening and attained a popu ... | 1991 | 1777389 |
| does hydrogen peroxide exist "free" in biological systems? | hydrogen peroxide (h2o2) can diffuse far from the site of production to intracellular locations where biological effects may be greater. the diffusion range is extended by h2o2 carriers formed spontaneously by hydrogen bonding with monomeric and polymeric compounds, including amino and dicarboxylic acids, peptides, proteins, nucleic acid bases, and nucleosides. hydrogen peroxide adducts (hpas) are readily synthesized, e.g., crystalline histidine (his)-h2o2 adducts. an equilibrium exists between ... | 1991 | 1778501 |
| the behavior of selected microorganisms during the manufacture of high moisture jack cheeses from ultrafiltered milk. | whole milk was pasteurized and concentrated two times by ultrafiltration. starter cultures, lactococcus lactis ssp. cremoris and lactococcus lactis ssp. lactis, were propagated in either reconstituted skim milk, two times uf retentate, or uf permeate, or a direct vat system was used for the starter culture. the cheese milk was simultaneously inoculated with starter culture and pseudomonas fragi 4973, staphylococcus aureus 196e, and salmonella typhimurium var. hillfarm. control whole milk, uf con ... | 1991 | 1779045 |
| magnesium transport in salmonella typhimurium: the influence of new mutations conferring co2+ resistance on the cora mg2+ transport system. | the cora mg2+ transport system of salmonella typhimurium mediates both influx and efflux of mg2+. mutations at the cora locus (83.5 min) confer resistance to co2+. using transposon mutagenesis, three additional co2+ resistance loci (corb, corc, and cord) were found and mapped to 55, 15, and 3min, respectively, on the s. typhimurium chromosome. no mutations corresponding to the reported corb locus at 95 min in escherichia coli were obtained. the corb, corc, and cord mutations confer levels of co2 ... | 1991 | 1779764 |
| regulation of toxa and rega by the escherichia coli fur gene and identification of a fur homologue in pseudomonas aeruginosa pa103 and pa01. | a multicopy plasmid containing the escherichia coli fur gene was introduced into pseudomonas aeruginosa strain pa103c. this strain contains a toxa-lacz fusion integrated into its chromosome at the toxa locus. beta-galactosidase synthesis in this strain is regulated by iron, as is seen for exotoxin a production. beta-galactosidase synthesis and exotoxin a production in pa103c containing multiple copies of e. coli fur was still repressed in low iron conditions. the transcription of rega, a positiv ... | 1991 | 1779768 |
| physiological effects of the lipopolysaccharide of vibrio vulnificus on mice and rats. | vibrio vulnificus is a pathogenic, marine, gram-negative bacterium which commonly enters and infects humans via open wounds or the ingestion of raw seafood. the lipopolysaccharide (lps) of v. vulnificus has recently been characterized, but the biological activity of this putative endotoxin is unknown. three treatment groups were used to test its activity: saline (negative control), the lps of salmonella typhimurium (a known endotoxin), and the lps of v. vulnificus. whereas, intravenous injection ... | 1991 | 1779875 |
| oxidative stress responses in escherichia coli and salmonella typhimurium. | oxidative stress is strongly implicated in a number of diseases, such as rheumatoid arthritis, inflammatory bowel disorders, and atherosclerosis, and its emerging as one of the most important causative agents of mutagenesis, tumorigenesis, and aging. recent progress on the genetics and molecular biology of the cellular responses to oxidative stress, primarily in escherichia coli and salmonella typhimurium, is summarized. bacteria respond to oxidative stress by invoking two distinct stress respon ... | 1991 | 1779927 |
| the role of intestinal microflora on the prevention of salmonella colonization in gnotobiotic chickens. | the possible role of the intestinal microflora in inhibiting the colonization of salmonella in the ceca of gnotobiotic chickens was investigated. in the cecal contents of newly hatched (2-day-old) and adult normal (7-mo-old) chickens, a larger number of escherichia coli and a smaller number of lactobacillus sp. were noticed in 2-day-old chickens than in adult chickens. gnotobiotic chickens treated with cecal contents from either newly hatched or adult birds were orally exposed to salmonella typh ... | 1991 | 1780261 |
| [the effect of cyclooxygenase inhibition on the indices of the thrombocyte-vascular link in hemostasis and on the free-radical processes of lipid oxidation in experimental salmonella intoxication]. | injection of salmonella typhimurium endotoxin to the laboratory animals (rabbits) in dose of 1 mg/ml (ld84) induces the particular changes in the thrombocyte vessels system of hemostasis: decrease of aggregatory ability of thrombocytes, increase of thromboxane a2 and prostacyclin activation of lipid peroxidation process. use of indomethacin--the cyclooxygenase inhibitor--leads to less progressive alterations of the studied parameters of the thrombocyte vessels hemostasis and lipid peroxidation p ... | 1991 | 1782274 |
| effect of the new immunostimulator hab 439 on cell-mediated immunity against intracellular bacteria. | the isoxazoline derivative hab 439 was tested for its enzyme inhibiting potency and was found to be an inhibitor of aminopeptidase b (ic50 = 22.5 micrograms/ml). in further immunopharmacological experiments its efficacy to stimulate cell-mediated immunity was evaluated. hab 439 was shown to stimulate dth-reaction against salmonella typhimurium and listeria monocytogenes. hab 439 protected animals against infection by reducing the bacterial load in livers and spleens and by decreasing the mortali ... | 1991 | 1783467 |
| regulation of compatible solute accumulation in salmonella typhimurium: evidence for a glycine betaine efflux system. | the regulation of glycine betaine accumulation has been investigated in salmonella typhimurium. the size of the glycine betaine pool in the cells is determined by the external osmotic pressure and is largely independent of the external glycine betaine concentration. analysis of the activity of the prop and prou transport systems suggests that other systems must be active in the regulation of the glycine betaine pool. addition of p-chloromercuribenzoate (pcmb) or p-chloromercuribenzene sulphonate ... | 1991 | 1783908 |
| effect of fructooligosaccharide on salmonella colonization of the chicken intestine. | the influence of fructooligosaccharide (fos) on the ability of salmonella typhimurium to grow and colonize the gut of chickens was investigated. in vitro studies showed that salmonella did not grow when fos was the sole carbon source. when fos was fed to chicks at the .375% level, little influence on salmonella colonization was observed. at the .75% level, 12% fewer fos-fed birds were colonized with salmonella compared with control birds. when chicks given a partially protective competitive excl ... | 1991 | 1784565 |
| analysis of an anaerobically induced promoter for the cobalamin biosynthetic genes in salmonella typhimurium. | we have identified an anaerobically induced promoter for the cobalamin biosynthetic (cob) genes. in a plasmid the cob promoter showed two of the three types of control of the intact chromosomal cob operon: anaerobic induction and camp stimulation. cobalamin repression was observed only in promoter fragments which included sequences far downstream of the transcription start site, suggesting that this control is post-transcriptional. one anaerobically induced transcript was identified and its 5' e ... | 1991 | 1787789 |
| a chimeric nucleotide-binding protein, encoded by a hisp-malk hybrid gene, is functional in maltose transport in salmonella typhimurium. | we have isolated a hybrid gene, composed of the first 455 nucleotides of hisp and nucleotides 275-1107 of malk, the genes coding for the nucleotide-binding components of the high-affinity transport systems for histidine and maltose in salmonella typhimurium, respectively. the fusion had occurred by recombination within 11 homologous base pairs located between the two dna fragments. in the chimeric protein peptidic motifs a and b, proposed to be part of the nucleotide-binding fold, originate from ... | 1991 | 1787792 |
| an investigation of the effects of four variables on the growth of salmonella typhimurium using two types of gradient gel plates. | the effect of four variables (ph, temperature, sodium chloride concentration and sodium nitrite concentration) on the growth of salmonella typhimurium cra663 was investigated using a two-dimensional gradient gel technique. two methods were used. in the first method the gradients comprised nacl and ph and in the second method a temperature gradient incubator was used to produce a temperature-ph gradient. using image analysis, the growth on the plates was depicted as three-dimensional wire frame g ... | 1991 | 1790103 |
| fate of unirradiated salmonella in irradiated mechanically deboned chicken meat. | mechanically deboned chicken meat was irradiated at 0, 1.25 and 2.50 kgy (cesium 137) and inoculated with salmonella dublin atcc 15480, salmonella enteritidis atcc 9186 or salmonella typhimurium atcc 14028. samples were then stored at 5 degrees c and 10 degrees c and were subjected to microbiological analysis directly after irradiation and inoculation (time 0), and after 24, 72, 120, 168 and 216 h of storage. samples stored at 20 degrees c were examined at time 0 and after 6, 12 and 24 h of stor ... | 1991 | 1790108 |
| structure and expression of the chlorobium vibrioforme hema gene. | the green sulfur bacterium, chlorobium vibrioforme, synthesizes the tetrapyrrole precursor, delta-aminolevulinic acid (ala), from glutamate via the rna-dependent five-carbon pathway. a 1.9-kb clone of genomic dna from c. vibrioforme that is capable of transforming a glutamyl-trna reductase-deficient, ala-dependent, hema mutant of escherichia coli to prototrophy was sequenced. the transforming c. vibrioforme dna has significant sequence similarity to the e. coli, salmonella typhimurium, and bacil ... | 1991 | 1793335 |
| prolonged environmental stress via a two step process selects mutants of escherichia, salmonella and pseudomonas that grow at 54 degrees c. | a prolonged incubation of escherichia, salmonella or pseudomonas at 48 degrees c with nalidixic acid selected mutants (t48) able to grow at 48 degrees c. a prolonged incubation at 54 degrees c of the t48 mutants selected mutants (t54) able to grow at 54 degrees c. these mutants were susceptible to the same bacteriophages as the original mesophilic strains. auxotrophic phenotypes of escherichia coli and salmonella typhimurium mesophilic parents were demonstrated by these mutants if they were cult ... | 1991 | 1793337 |
| a strategy for ranking environmentally occurring chemicals. part vi. qsars for the mutagenic effects of halogenated aliphatics. | a strategy for the systematic analysis and priority ranking of environmental chemicals has been applied to a class of 58 halogenated aliphatic hydrocarbons. a training set of ten compounds representing this class, was selected by statistical design. the training set compounds were then subjected to biological testing in the salmonella typhimurium reverse mutation assay (ames test). the measured biological data, recorded as dose-response curves, were analyzed to determine the mutagenic potency (s ... | 1991 | 1793683 |
| structure-activity relationships of bacterial mutagens related to 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5h)-furanone: an emphasis on the effect of stepwise removal of chlorine from the dichloromethyl group. | the salmonella typhimurium (ta100) mutagenicities of six structural analogues of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5h)-furanone (mx) were determined and compared. these were also compared to previously determined mutagenicities for another four analogues. this study was conducted for the primary purpose of ascertaining the effect of c-6 chlorine-by-hydrogen replacement on mutagenicity. the compounds assayed were 3-chloro-4-(chloromethyl)-5-hydroxy-2(5h)-furanone (3), 3-chloro-4-(chlorometh ... | 1991 | 1793803 |
| in-vitro testing and the carcinogenic potential of several nitrosated indole compounds. | 4-chloro-methoxyindole is a naturally occurring compound in vicia faba which can easily react with nitrite to form a n-nitroso compound. in this in vitro study, the potential genotoxic effects of nitrosated 4-chloro-6-methoxyindole and its structural analogue 4-chloroindole were evaluated for the first time by using both salmonella and chinese hamster v79 cells. additionally, the inhibition of gap junctional intercellular communication in v79 cells by these compounds was determined; this is a va ... | 1991 | 1794111 |
| evaluation of the magnetic immuno pcr assay for rapid detection of salmonella. | a new technique, the magnetic immuno pcr assay (mipa), has been developed for the detection of salmonella. the assay utilizes magnetic particles coated with monoclonal antibodies against salmonella to extract these bacteria from the sample. trapped bacteria are lysed, and the supernatant, which contains bacterial dna, is then subjected to the polymerase chain reaction (pcr) using primers from the salmonella typhimurium origin of dna replication to amplify a 163 bp region. the specificity of the ... | 1991 | 1794363 |