Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| contribution to the study of live streptomycin-dependent salmonella vaccines: the problem of reversion to a virulent form. | the recovery of virulence by means of reversion of a live streptomycin-dependent (sm d) salmonella typhimurium vaccine was studied in cd-1 swiss mice. initially, a one-step sm d mutant was obtained from a virulent streptomycin-sensitive (sm s) s. typhimurium strain. afterwards, two pools of streptomycin-independent (sm i) revertants were prepared from the sm d strain. the virulence of the sm d strain and of the sm i revertants was tested intraperitoneally. in the virulence testing the original s ... | 1975 | 1100711 |
| experimental model of oral antityphoid vaccination with live streptomycin-dependent salmonella typhimurium in c57bl/6 mice. | the present experimental model offered the opportunity to study particular aspects concerning the avirulence stability of live streptomycin-dependent (sm d) salmonella vaccines, under conditions resembling human enteric fever. the results seem to indicate that, in practice, the risk of reversion to a virulent form during oral antityphoid vaccination with sm d strains remains slight even after the interruption of concomitant streptomycin administration. | 1975 | 1100712 |
| the effect of antibiotic therapy on the faecal excretion of salmonella typhimurium by experimentally infected chickens. | chickens in groups of 40 were infected orally with a nalidixic acid-resistant mutant of salmonella typhimurium and then fed continuously on diets containing ampicillin, chloramphenicol, furazolidone, neomycin, oxytetracycline, polymixin, spectinomycin, streptomycin or a mixture of trimethoprim and sulphadiazine. the amount of s. typhimurium excreted in their faeces was estimated at intervals by culture on brilliant green agar containing sodium nalidixate, both direct and after enrichment in sele ... | 1975 | 1100714 |
| the effect of feeding diets containing permitted antibiotics on the faecal excretion of salmonella typhimurium by experimentally infected chickens. | groups of 45 chickens were fed continuously on diets containing 10 or 100 mg./kg. of different 'growth-promoting' antibiotics and infected orally with a nalidixic acid-resistant mutant of salmonella typhimurium. the amount of s. typhimurium organisms excreted in their faeces was estimated by culturing them at weekly intervals and in a standard manner on plates of brilliant green agar containing sodium nalidixate, both direct and after enrichment in selenite broth. all of four groups fed diets co ... | 1975 | 1100715 |
| dna release as a direct measure of microbial killing. i. serum bactericidal activity. | a new method for quantification of microbial killing is presented, based upon the assumption that release of dna from an organism can be taken as direct evidence of cell death. the assay was applied to measurement of serum bactericidal activity. a "serum-sensitive" escherichia coli, whose dna was pre-labeled with [14c] thymidine, released 95 to 100% of its radioactivity upon exposure to human serum for 120 min. this was accompanied by a fall in viability with less than 0.1% of the bacteria survi ... | 1975 | 1100731 |
| temporary expression of flagellar phase-1 in phase-2 clones of diphasic salmonella. | diphasic salmonella strains, salmonella typhimurium tm2, s. abony sw803 and their derivatives differing in flagellar shape and antigen type, were found to produce copolymer segments of phase-1 and phase-2 flagellins among flagella in phase 2, except for a strain which is non-flagellate in phase 1. the copolymer segments were not detected in phase-1 clones of any of the strains. the wave-forms of the copolymers are homologous with those of the copolymer filaments obtained by in vitro reconstituti ... | 1975 | 1100772 |
| evidence for an s-adenosylmethionine requirement in the chemotactic behavior of salmonella typhimurium. | 1975 | 1100856 | |
| isolation, characterization and complementation of salmonella typhimurium chemotaxis mutants. | 1975 | 1100857 | |
| peptidases and proteases of escherichia coli and salmonella typhimurium. | 1975 | 1101808 | |
| substrate specificity of salmonella typhimurium rnaase iii and the nature of products formed. | rnaase iii, an endonuclease specific for double-stranded substrates, has been obtained in a highly purified form from extracts of salmonella typhimurium. poly (i-c) and a mixture of poly(a) and poly(u) (1 : 1), the latter in presence of 5 mm mg2+, act as excellent substrates. poly(i-c) is only partially hydrolysed by rnaase iii and the product or products are acted upon by both rnaase i and rnaase ii indicating that the products may be oligonucleotides. this conclusion is supported by two-dimens ... | 1975 | 1101968 |
| epoxides metabolically produced from some known carcinogens and from some clinically used drugs. i. differences in mutagenicity. | the epoxide metabolites of two clinically used drugs and an experimental psychotropic agent, carbamazepine 10,11-oxide, cyproheptadine 10,11-oxide and cyclobenzaprine 10,11-oxide, were fully devoid of any mutagenic activity under conditions where k-region-epoxide metabolites of some known carcinogens, such as benzo(a)pyrene, proved to be potent frameshift mutational agents for salmonella typhimurium ta 1537 and ta 1538. all epoxides tested were non-mutagenic for ta 1535, designed to detect subst ... | 1975 | 1102464 |
| pyrimidine biosynthetic enzymes of salmonella typhimurium, repressed specifically by growth in the presence of cytidine. | the repressive effects of exogenous cytidine on growing cells was examined in a specially constructed strain in which the pool sizes of endogenous uridine 5'-diphosphate and uridine 5'-triphosphate cannot be varied by the addition of uracil and/or uridine to the medium. five enzymes of the pyrimidine biosynthetic pathway and one enzyme of the arginine biosynthetic pathway were assayed from cells grown under a variety of conditions. cytidine repressed the synthesis of dihydroorotase (encoded by p ... | 1975 | 1102530 |
| comparison of the cell envelope structure of a lipopolysaccharide-defective (heptose-deficient) strain and a smooth strain of salmonella typhimurium. | the cell envelope structure of salmonella typhimurium lt2, which has a heptose-deficient lipopolysaccharide (lps), is significantly different from that of an isogenic strain with a normal lps. the rough strain, when examined by freeze-etching, lacks most surface structures that are routinely present in the smooth strain (surface particles and flagella) and has few transmemberane studs in the cytoplasmic membrane (those present are generally found in aggregates), and the outer membrane cleavage i ... | 1975 | 1102537 |
| outer membrane of salmonella typhimurium: chemical analysis and freeze-fracture studies with lipopolysaccharide mutants. | the outer membrane layer of the cell wall was isolated from wild-type salmonella typhimurium lt2 as well as from its mutants producing lipopolysaccharides with shorter saccharide chains. chemical analysis of these preparations indicated the following. (i) the number of lipopolysaccharide molecules per unit area was constant, regardless of the length of the saccharide side chain in lipopolysaccharide. (ii) in contrast, in "deep rough" (rd or re) mutants producing the lipopolysaccharides with very ... | 1975 | 1102538 |
| unusual enterobacteriaceae: lactose-positive salmonella typhimurium which is endemic in são paulo, brazil. | since 1971 a lactose-positive (lac+) salmonella typhimurium variety copenhagen has been endemic in the city of sao paulo. the strain is a strong lactose fermenter and resembles escherichia coli on primary plating media and in triple sugar iron agar. although most isolates of the strain have uniform properties, some have slightly different antigens, antibiograms, phage types, or fermentation patterns. most isolates have come from stools of infants under 1 year of age and are probably hospital acq ... | 1975 | 1102562 |
| the role of methionine transport-defective mutations in resistance to methionine sulphoximine in salmonella typhimurium. | two classes of salmonella typhimurium mutants resistant to inhibitory methionine analogues and defective in methionine transport have been examined. a mutant of the first class, resistant to alpha-methylmethionine, was shown by conjugation analysis to possess a single mutation in the metp gene which specifies a methionine transport system. mutants of the second class, resistant to alpha-methylmethionine and methionine sulphoximine, possess two mutations. one is in the metp gene, which accounts f ... | 1975 | 1102923 |
| dna restriction and modification systems in salmonella. iii. sp, a salmonella potsdam system allelic to the sb system in salmonella typhimurium. | by screening 42 salmonella strains with p3, a temperate bacteriophage with an unusually wide host range, five new dna restriction and modification systems (r-m systems) were identified in five different serotypes in kauffmann-white group c. one of these systems, sp, in a pl-sensitive strain of s. potsdam, was analyzed genetically by pl transduction methods in which sp was transferred into s. typhimurium and c. coli/s. typhimurium hybrids. it was found that the genes of the sp system were allelic ... | 1975 | 1102934 |
| integrative suppression of a dnaa mutation in salmonella typhimurium. | integrative suppression of a dnaa mutation in salmonella typhimurium may result from the integration of f'lac or f'his into the chromosome in the left hand side of the chromosomal map. the suppressed revertants resulting from this integration do not contain dna of the f' elements in the covalently closed circular (ccc)1 form but still contain the ccc dna of the cryptic lt2 plasmid. two suppressed revertants isolated from dnaa/f- strains were found in which the suppression of dnaa character was a ... | 1975 | 1102937 |
| location of the argr gene on the chromosome of salmonella typhimurium. | the regulatory gene (argr) for the arginine biosynthetic pathway has been located at 106 min on the chromosome of s. typhimurium. in addition, the location of the gene specifying cytosine deaminase (cod) has been more precisely determined. | 1975 | 1102941 |
| inhibition of macrophage migration in salmonella immunity. | protein antigens were prepared from rough strains of salmonella typhimurium and s. dublin by phenol and veronal-buffer extraction. it was shown that the in vitro migration of peritoneal exudate cells from guinea pigs that were immunized with rough avirulent mutants could be inhibited effectively with these antigens. the cells obtained from s. typhimurium-immunized guinea pigs were also sensitive to s. dublin antigens and vice versa. a degree of sensitivity and inhibition could be demonstrated co ... | 1975 | 1103043 |
| mutagenic and cytotoxic activity of benzol[a]pyrene 4,5-, 7,8-, and 9,10-oxides and the six corresponding phenols. | the benzo[a]pyrene 4,5-, 7,8-, and 9,10-oxides and the six corresponding phenols (4-, 5-, 7-, 8-, 9-, and 10-hydroxybenzo[a]pyrene) have been tested for mutagenic and cytotoxic activity in bacteria and in a mammalian cell culture system. benzo[a]pyrene 4,5-oxide (k-region) was highly mutagenic in two histidine-dependent strains (ta1537 and ta1538) of salmonella typhimurium which detect frameshift mutagens. in contrast, benzo[a]pyrene 7,8- and 9,10-oxides were less than 1% as mutagenic as the 4,5 ... | 1975 | 1103140 |
| histidine regulation in salmonella typhimurium: an activator attenuator model of gene regulation. | an activator-attenuator model of positive control, a s opposed to the classic repressor-operator model of negative control, is proposed for the major operon-specific mechanism governing expression of the histidine gene cluster of salmonella typhimurium. evidence for this mechanism is derived from experiments performed with a coupled in vitro transcription-translation system, as well as with a minimal in vitro transcription system [kasai, t. (1974) nature 249, 523--527]. the product (g enzyme, or ... | 1975 | 1103149 |
| cellular and humoral aspects of host resistance in murine salmonellosis. | mice were challenged with a highly virulent strain of salmonella typhimurium by intraperitoneal injections. at relatively low infecting doses, immunizations with either viable attenuated or heat killed salm. typhimurium were found to be equally protective against otherwise fatal infections. pre-opsonization of virulent salmonellae significantly increased the survival rate of mice infected with small numbers of the pathogen. by a cell culture method, peritoneal macrophages of mice were shown to b ... | 1975 | 1103931 |
| synthesis and localisation of escherichia coli udp-glucose hydrolase (5'-nucleotidase), and demonstration of a cytoplasmic inhibitor of this enzyme in salmonella typhimurium. | 1975 | 1103973 | |
| mutagenicity of nitrofurans, nitrothiophenes, nitropyrroles, nitroimidazole, aminothiophenes, and aminothiazoles in salmonella typhimurium. | thirty-two heterocyclic compounds, including 24 nitroheterocycles, 7 aminoheterocycles and derivatives, and 1 thiophene lacking a nitro group, were tested for mutagenic activity in salmonella typhimurium ta 98 and ta 100. all the nitroheterocycles (11 new), including nitrofurans, nitrothiophenes, nitropyrroles, and 1 nitroimidazole, were mutagenic in ta 100; 13 were also mutagenic in ta 98. 5-nitro-2-furoic acid, a noncarcinogen, was mutagenic in ta 100. seven carcinogenic nitroheterocycles were ... | 1975 | 1104157 |
| the reactivity and carcinogenicity of aflatoxin b1-2,3-dichloride, a model for the putative 2,3-oxide metabolite of aflatoxin b1. | aflatoxin b1-2,3-dichloride (afb1-cl2) was synthesized as a model for the probable ultimate carcinogen, aflatoxin b1-2,3-oxide. as expected for aflatoxin b1-2,3-oxide, afb1-cl2 has an electrophilic carbon 2; it decomposed in water (half-life of 0.5 min in 10% dimethyl sulfoxide, ph 7.4) with the formation of 3-chloro-2,3-dihydro-2-hydroxyaflatoxin b1 and 2,3-dihydro-2,3-dihydroxyaflatoxin b1. afb1-cl2 formed covalent adducts with dna and rna with retention of one-half of the chlorine; the major ... | 1975 | 1104159 |
| mutagenic activity of platinum and ruthenium complexes. | cis-dichlorodiammineplatinum(ii) [cis-ptcl2(nh3)2] and dichlorotetrakis (dis-methylsulfoxide) ruthenium(ii) [rucl2(dmso)4] have been tested as mutagens for strains of salmonella typhimurium carrying the hisg46 missense mutation. their activity, which has been compared with the activity of mitomycin c, depends on the presence in the test bacteria of the pkm101 plasmid and is affected in various ways by the function of the excision repair system. more precisely, mitomycin c is mutagenic only for s ... | 1975 | 1104208 |
| effect of lipopolysaccharide and lipid a on mouse liver pyruvate kinase activity. | several investigators have reported lipid a as the biologically active unit in the lipopolysaccharide (lps) molecule. to determine if lipid a was responsible for the reported increases in pyruvate kinase, mice were injected with endotoxin from salmonella typhimurium sr-11, the re mutant of salmonella minnesota r 595, and lipid a-bovine serum albumin conjugate. the livers were homogenized and the activity of pyruvate kinase was measured. similar increases in enzyme were obtained with all three pr ... | 1975 | 1104489 |
| salmonellosis in a human infant, a cat, and two parakeets in the same household. | salmonellosis occurred in a human infant, cat, and 2 pet parakeets in the same household. salmonella typhimurium var copenhagen was isolated from all 4 subjects; however, its original source was never determined. the parakeets subsequently died, and necropsy revealed enteritis, foci of hepatic necrosis, and leptomeningitis. | 1975 | 1104547 |
| trans-recessive mutation in the first structural gene of the histidine operon that results in constitutive expression of the operon. | the first enzyme for histidine biosynthesis, encoded in the hisg gene, is involved in regulation of expression of the histidine operon in salmonella typhimurium. the studies reported here concern the question of how expression of the histidine operon is affected by a mutation in the hisg gene that alters the allosteric site of the first enzyme for histidine biosynthesis, rendering the enzyme completely resistant to inhibition by histidine. the intracellular concentrations of the enzymes encoded ... | 1975 | 1104579 |
| fine-structure genetic map of the cysb locus in salmonella typhimurium. | a genetic map of the cysb region of the salmonella typhimurium chromosome was constructed using bacteriophage p22-mediated transduction. strains bearing delta (supx cysb) mutations were employed to divide this regulatory locus into 12 segments containing a total of 39 single-site mutations. twenty-five of these single-site mutations were further ordered by reciprocal three-point crosses. the results do not support the concept of multiple cistrons at cysb and suggest that the abortive transductan ... | 1975 | 1104581 |
| genes affecting coliphage bf23 and e colicin sensitivity in salmonella typhimurium. | rough strains of salmonella typhimurium were sensitive to coliphage bf23. spontaneous mutants resistant to bf23 (bfe) were isolated, and the trait was mapped using phage p1. the bfe gene in s. typhimurium was located between argf (66% co-transducible) and rif (61% co-transducible). the bf23-sensitive s. typhimurium strains were not sensitive to the e colicins. cells of these rough strains absorbed colicin, as measured by loss of e2 or e3 killing units from colicin solutions and by specific adsor ... | 1975 | 1104583 |
| transfectability of rough strains of salmonella typhimurium. | cells of rough (but not smooth) strains of salmonella typhimurium become competent for transfection by phage p22 deoxyribonucleic acid after treatment with 0.1 m cacl2. the yield of infectious centers is about 10(-8) per genome equivalent of deoxyribonucleic acid. however, different sorts of rough strains vary in their ability to become competent in a fashion that can be correlated with the level of the genetic block in cell wall lipopolysaccharide synthesis. the most amenable strains are blocke ... | 1975 | 1104596 |
| antimicrobial resistance and r-factor transfer among isolates of salmonella in the northeastern united states: a comparison of human and animal isolates. | the antimicrobial susceptibility of 718 isolates of salmonella from humans and of 688 isolates from animals was examined. of the 46 different serotypes among the isolates from humans, salmonella typhimurium accounted for 34%. thirty percent of isolates were resistant to one or more antibiotic(s). resistance to streptomycin was most common; resistance to tetracycline was next most common. over 50% of isolates of s. typhimurium and salmonella newport were resistant to four antibiotics. resistance ... | 1975 | 1104721 |
| mutations affecting aromatic amino acid transport in escherichia coli and salmonella typhimurium. | a genetic locus, arot, located between chr and the trp operon in salmonella typhimurium, and similar genes, aror and aros, near the trp locus of escherichia coli, were found to be involved in the transport of aromatic amino acids. genetic lesions at these loci cause a variable diminution in uptake and accumulation of aromatic amino acids, alanine and glycine compared with the wild type. the f'trp episome carries the aro r locus. curing an e. coli strain of the f'trp episome which covers a chrom ... | 1975 | 1104763 |
| instability of the flac+ factor in a dnac mutant of salmonella typhimurium. | 1975 | 1104765 | |
| transduction by phage p1cm clr-100 in salmonella typhimurium. | phage p1 does not adsorb to s. typhinurium wild type cells. it does adsorb to rough derivatives including strains with mutations in the gale gene. phage strain p1cm clr-100 can be efficiently propagated in s. typhimurium derivatives, either by induction of a lysogene, or by lytic infection. phage p1 lysates are able to mobilize genetic markers in a generalized fashion. the transduction system is essentially identical to that in escherichia coli, except that cacl2 is not required for efficient ad ... | 1975 | 1105147 |
| appearance of transducing particles and the fate of host dna after infection of salmonella typhimurium with p22-mutants with increased transducing ability (ht-mutants). | the kinetics of production of transducing particles for different bacterial markers were followed by premature lysis of salmonella typhimurium cells infected with p22 phages. the were compared for cells infected with wild type phage or with ht-mutants which show increased transduction frequencies. measuring the sedimentation velocity of bacterial dna of cells infected with wild type or ht-phages, it was shown that: a) there is no cutting of dna at random; b) original fragments necessary for pack ... | 1975 | 1105152 |
| pand, a new chromosomal locus of salmonella typhimurium for the biosynthesis of beta-alanine. | three mutants of salmonella typhimurium lt2, which required either pantothenate or beta-alanine for growth, were obtained after treatment with n-methyl-n'-nitro-n-nitrosoguanidine. their phenotype was: sm30 pan-, sm31 pan- met-, sm32 pan- thi- (requirement for the thiazole-moiety of thiamine). neither aspartate, dihydrouracil, nor beta-ureidopropionate replaced beta-alanine as growth factor. by conjugation it was found that the three genetic lesions (pan-, met-, thi-) were located at about minut ... | 1975 | 1105156 |
| plasmid-determined alterations of salmonella typhimurium lipopolysaccharides. | salmonella typhimurium rc902 infected with derepressed colib mutants gave rise to changes in the composition of bacterial lipopolysaccharides (lps). bacteria carrying colibdrd7, derepressed in transfer, exhibited a marked decrease in the content of all 0-side-chain sugars of lps. similar effect were found upon the introduction of r64-11, also derepressed in transfer. in lps of s. typhimurium containing colibdrd2, derepressed in colicin synthesis, a decrease of abequose content associated with an ... | 1975 | 1105157 |
| the relationship of 2-acetamidofluorene mutagenicity in plate tests with its in vivo liver cell component distribution and its carcinogenic potential. | using a plating technique, the mutagenic potentials of 2-acetamidofluorene (aaf) and n-hydroxy-aaf were examined after metabolic activation by liver preparations from different animals. animals used were: male and female rats; male rats treated with 3-methylcholanthrene (mc); male rats treated with aaf; hamsters; guinea pigs; cotton rats and baboons. irrespective of the animal susceptibility to aaf carcinogenesis, mutation frequency was always increased in the salmonella typhimurium ta 1538 test ... | 1975 | 1105163 |
| guanosine 5'-diphosphate 3'-diphosphate (ppgpp): positive effector for histidine operon transcription and general signal for amino-acid deficiency. | maximal expression of the histidine operon of salmonella typhimurium in a coupled in vitro transcription-translation system is strongly dependent upon addition of guanosine 5'-diphosphate 3'-diphosphate (ppgpp). this requirement for ppgpp is exerted at the level of transcription through a mechanism distinct from the his-operon-specific regulatory mechanism. in vivo derepression of the his operon is markedly defective when histidine starvation is imposed on a rela mutant--unable to rapidly increa ... | 1975 | 1105582 |
| association of salmonella mutants with germfree rats: site specific model to detect carcinogens as mutagens. | an association of the histidine auxotroph of salmonella typhimurium (strain ta1538) within the gastrointestinal tract of otherwise germfree sprague-dawley rats is maintained during periods of observation lasting as long as 7 months. the bacteria are found at levels exceeding 10(7) per g in the forestomach and at levels greater than 10(8) per g in the lower bowel and in the feces. only approximately 10(4) bacteria per g are found in the posterior stomach and in the upper small intestine. the asso ... | 1975 | 1105585 |
| [transferable gentamicin resistance in multiresistant strains of salmonella typhimurium]. | 1975 | 1105740 | |
| mode of growth and division of salmonella typhimurium. | a temperature-sensitive strain (hd 20) of salmonella typhimurium is described. at restrictive temperature this strain shows an envelope alteration and a defect in division associated with an increase in cell diameter. on a shift to 42 degrees c there is residual division for ca. 30 min and then no further increase in cell number. in minimal medium (mm) at 42 degrees c cell diameter remains unchanged for about one mass doubling and then increases. from measurements of cell elongation, it is concl ... | 1975 | 1105991 |
| influence of chlortetracycline and chlortetracycline + sulfamethazine supplemented feed on the incidence, persistence and antibacterial susceptibility of salmonella typhimurium in experimentally inoculated calves. | 1975 | 1106071 | |
| influence of age on the serological response of chickens to salmonella typhimurium infection. | after chickens 1-126 days old were infected orally with salmonella typhimurium, antibody responses were determined by microagglutination (ma) and microantiglobulin (mag) test procedures. in all groups six weeks old or older, a high and continuing level of salmonella group b antibody was demonstrated by the mag test but not by the ma test. serological response was maximal at about 15 weeks or later. reinoculation with s. typhimurium 129 days after initial infection elevated antibody titers in all ... | 1975 | 1106387 |
| mutagenic activity of anthraquinone derivatives used as dyes in a textile factory. | some anthraquinone derivatives used as dyes in a textile factory have been tested for their mutagenic activity on the ames' strains of salmonella typhimurium. 1-amino-4-hydroxy-anthraquinone proved to be a mutagen of the frameshift type. it is active without need of metabolic activation. studies are in progress in order to clarify if the mutagenic activity of other substituted anthraquinones, which do not act as direct mutagens, can become evident after metabolic activation. further tests are ne ... | 1975 | 1106724 |
| heterogeneity of lipopolysaccharides. analysis of polysaccharide chain lengths by sodium dodecylsulfate-polyacrylamide gel electrophoresis. | lipopolysaccharide preparations from r(rough) escherichia coli o8-,sr(semirough) salmonella typhimurium and s (smooth) strains e. coli o8 and citrobacter 396 were disintegrated with sodium dodecylsulfate and subjected to polyacrylamide gel electrophoresis in the presence of 1% sodium dodecylsulfate. the results obtained were compared with those obtained from the same lipopolysaccharide preparations by degradation analysis. in dodecylsulfate gel electrophoresis the lipopolysaccharide preparation ... | 1975 | 1107034 |
| involvement of the phosphotransferase system in galactose transport in salmonella typhimurium. | 1976 | 1107070 | |
| phagocytosis as a surface phenomenon. v. contact angles and phagocytosis of rough and smooth strains of salmonella typhimurium, and the influence of specific antiserum. | the angle made by a drop of saline in contact with a monolayer of salmonella typhimurium or phagocytic cells, the contact angle, is a measure of their relative interfacial tension, and is predictive of a successful phagocytosis. smooth strains of s. typhimurium possess a contact angle lower than the phagocytic cells and resist phagocytosis. rough strains have an angle higher than the phagocytes and are readily engulfed. the lower contact angle of smooth strains can be increased by treatment with ... | 1975 | 1107214 |
| isolation & characterization of an l-arabinose negative mutant of salmonella typhimurium. | 1975 | 1107216 | |
| ineffectiveness of vi and chemically treated endotoxins as typhoid vaccines in mice challenged with a salmonella typhosa-salmonella typhimurium hybrid. | purified vi antigen, acetic anthydride-treated salmonella typhosa endotoxin, and potassium methylate-treated s. typhosa endotoxin employed as vaccines in swiss white mice failed to protect these animals against challenge with a virulent s. typhimurium hybrid expressing s. typhosa antigens. | 1975 | 1107227 |
| regulatory mutants and control of cysteine biosynthetic enzymes in salmonella typhimurium. | the cysb region in salmonella typhimurium regulates in a positive manner the noncontiguous structural genes for the enzymes responsible for sulfate reduction in cysteine biosynthesis. we treated three cysb mutants with chemical mutagens and selected 81 secondary mutants in which the inability to utilize sulfate was suppressed. growth experiments on the suppressed mutants showed that the original loss of sulfate utilization had been corrected to varying degrees and that portions of the pathway ha ... | 1976 | 1107320 |
| survival of salmonella east bourne and salmonella typhimurium in chocolate. | experiments were carried out to assess the reduction rate of two salmonella strains (s. eastbourne and s. typhimurium) in chocolate bars. after artificial contamination of chocolate, after 'conching', with about 10(6) s. eastbourne/g. this organism was still recovered after 9 months storage. the strain of s. typhimurium was less resistant. both serotypes died off more rapidly in bitter chocolate than in milk chocolate. after contamination with a smaller dose (about 10(3)/g.) with these two serot ... | 1976 | 1107412 |
| the virulence of trimethoprim-resistant thymine-requiring strains of salmonella. | a thymine-requiring (thy-), trimethoprim-resistant (tmpr) mutant isolated from the faeces of chickens experimentally infected with salmonella typhimurium and treated with mixture of trimethoprim and sulphadiazine was less virulent for chickens than the parent strain and a thy+tmps revertant prepared in vitro from the mutant. the difference in chicken-virulence was more noticeable when the strains were administered orally than when they were administered subcutaneously. all tmpr mutants prepared ... | 1976 | 1107416 |
| genetics of resistance to infection with salmonella typhimurium in mice. | eight strains of inbred mice fell into two sharply defined groups. four strains (cba, a/jax, c3h/he, and dba/2) were resistant (ld50, greater than 10(5)) to salmonella typhimurium c5 given subcutaneously. the other four strains (balb/c, c57bl, b10.d2 [new line], and dba/1) were susceptible (ld50, less than 10). no intermediate resistance was seen. examination of the f1, f2, and parental backcross generations bred from matings of cba and balb/c mice showed that resistance behaved as a simple mend ... | 1976 | 1107437 |
| a comparative study on the genetic effects of hycanthone and oxamniquine. | oxamniquine (uk-4271; 6-hydroxymethyl-2-isopropylaminomethyl-7-nitro-1,2,3,4-tetrahydroquinoline) is a new schistosomicidal agent currently undergoing clinical investigation in south america. essentially a complete cure rate against brazilian schistosoma mansoni has been seen in adults with a single im dose of 7.5 mg/kg or a single oral dose of 15 mg/kg. these regimens were tolerated without significant toxicity. to assess its mutagenic potential, oxamniquine was examined in a battery of genetic ... | 1975 | 1107579 |
| genetic analysis of mutants of escherichia coli k12 and salmonella typhimurium lt2 deficient in hydrogenase activity. | a genetic study of mutants deficient in hydrogenase activity was performed. in e. coli, the affected gene (hyd) is located at 51 min, between cys c and nal b; in s. typhimurium, it probably lies in the homologous region of the chromosome. | 1975 | 1107810 |
| regulation of histidine operon does not require hisg enzyme. | mutations are described which delete all or part of the first structural gene (hisg) of the histidine operon of salmonella typhimurium. physiological regulation of histidine enzymes occurs normally in strains carrying any deletion that has both endpoints within the hisg gene. constitutive high operon expression is observed in strains carrying any hisg deletion and an unlinked regulatory mutation, hist1504. these results strongly indicate that the hisg protein is not an essential component of the ... | 1975 | 1108009 |
| [case of food poisoning caused by salmonella typhimurium]. | 1975 | 1108447 | |
| [study of the sensitivity of a morphological mutant of s. typhimurium to irradiation]. | morphological salmonella typhimurium lt2 wt--ed 143 mutant was similar by the character of the uv-sensitivity to the lon-mutants of escherichia coli k-12. the paper treats of the data on the uv-sensitivity of the mutant and the initial strains at various growth phases, by the capacity to restore the irradiated p22 and felix o bacteriophages and by the effect of various postradiational treatment on the irradiated strains. data are presented on densitometry of the membrane proteins of the initial ... | 1975 | 1108536 |
| canine salmonellosis: a review and report of dog to child transmission of salmonella enteritidis. | dogs have been shown to harbor 53 salmonellae serotypes. multiple simultaneous infections with 2 to 4 serotypes have been observed. the prevalence of canine salmonellosis may be a high as 27 per cent. salmonella typhimurium and s. anatum are the most common etiologic agents. dogs commonly experience a sub-clinical course of salmonellosis. some investigators state that the dog may serve as a source of human infections. a few reports in the literature have documented this fact. the transmissions ... | 1976 | 1108681 |
| influence of subtherapeutic levels of oxytetracycline on salmonella typhimurium in swine, alves, and chickens. | subtherapeutic levels of oxytetracycline in animal feeds have been evaluated to determine their influence on the relative quantity, prevalence, shedding, and antibiotic susceptibility of salmonella typhimurium in swine, calves, and chickens, when compared with nonmedicated controls. the medicated groups were fed rations containing oxytetracycline commencing 5 days prior to oral inoculation with s. typhimurium and continuing through a 28-day post-inoculation period. colonization of s. typhimurium ... | 1975 | 1108781 |
| man, his animals and salmonella typhimurium. | 1975 | 1110309 | |
| the protection of mice against experimental infection by means of immunization with enriched membrane fraction of salmonella typhimurium. | 1975 | 1112368 | |
| alterations in hepatic chromatin template availability during infection. | hepatic chromatin was isolated from rats at various times after inoculation with either live or heat-killed bacteria. the chromatin was assayed under conditions that allow determination of the dna template available to support in vitro transcription. both a fulminant diplococcus pneumoniae and a milder salmonella typhimurium infection produced time-related increases in hepatic chromatin template availability when compared to chromatin isolated from rats inoculated with heat-killed bacteria. both ... | 1975 | 1130518 |
| aflatoxicol h1: a major metabolite of aflatoxin b1 produced by human and rhesus monkey livers in vitro. | among the major metabolites of aflatoxin b1 produced by human and monkey livers in vitro is a derivative with the ketone carbonyl on the cyclopentane ring reduced to a secondary alcohol, and a hydroxyl introduced onto the carbon beta to the alcohol group. the metabolite was formed from aflatoxin b1 at a level similar to that of aflatoxin m1.both the microsomal hydroxylase and the cytoplasmic reductase systems are required for its formation. bioassay using chicken embryos and a mutant of salmonel ... | 1975 | 1135508 |
| endotoxin from fusobacterium necrophorum of bovine hepatic abscess origin. | the endotoxic activity of fusobacterium necrophorum bov 5 was investigated. the supernatant (s) fluid and cell wall (cw) preparation, obtained after differential centrifugation of the ruptured cell mass, were lethal for mice. the toxicity of the s fluid was stable during prolonged storage, treatment with formalin, and heating for 15 minutes at 80, 100, and 121 c, but was destroyed by alkaline hydrolysis with 0.25 n naoh. the toxic factor was found in a high molecular weight (mw) fraction after g ... | 1975 | 1147341 |
| stimulation of derepressed enzyme synthesis in bacteria by growth on sublethal concentrations of chloramphenicol. | culturing of salmonella typhimurium or escherichia coli cells in the presence of low concentrations (</=1 mug/ml) of chloramphenicol (cap) permitted exponential growth, but at doubling times up to twice those of controls. when such cultures were subsequently starved for uracil or arginine, derepression of aspartate transcarbamylase (atcase) or ornithine transcarbamylase, respectively, was enhanced three- to 10-fold as compared to cultures not exposed to cap. enhancement of beta-galactosidase syn ... | 1975 | 1147588 |
| the middleton outbreak: 125 cases of foodborne salmonellosis resulting from cross-contaminated food items served at a picnic and a smorgasbord. | one hundred and twenty-five of 173 people who ate at a picnic and/or a smorgasbord prepared by a bar-restaurant in a midwestern town in september 1973 developed diarrhea, abdominal cramps, and other symptoms 23 hours (median time) later. eleven were hospitalized. stool cultures from 18 ill individuals grew salmonella infantis, salmonella agona, and salmonella schwarzengrund. stool cultures from 5 of 8 restaurant employees grew s. infantis or s. agona. cultures of remaining foods and food-contact ... | 1975 | 1171616 |
| studies on the methyl green-dna complex and its dissociation by drugs. | spectrophotometric results indicated that methyl green bound stably to native calf thymus dna and to poly[d(a-t)] but to a lesser extent to phix 174 dna, trnas, and poly(dg-dc), a copolymer that exists preferentially in the a conformation. exposing the methyl green-dna complex to graded concentrations of ethyl alcohol liberated part of the dye slowly by a zero-order reaction; higher alcohol concentrations which cause the b leads to a transition of dna released the bulk of methyl green. the visco ... | 1975 | 1191628 |
| [bacteriological study of the intestinal flora of bats (desmodus rotundus) (author's transl)]. | stools of 100 bats trapped in the town of anhembi, state os são paulo, brazil, were examined bacteriologically. hemolityc and non hemolytic strains of escherichia coli were found most frequently (29.5%) followed by proteus group (27%) and staphylococcus (20%). from nine samples of stools the authors isolated salmonella typhimurium. | 1975 | 1236052 |
| [blood cultures-bacteriological and drug resistance culture (author's transl)]. | blood cultures of 24 patients from the hospital das clinicas da faculdade de ciências médicas e biológicas de botucatu showed a prevalence of gram-negative isolates (83%) over gram-positive (16%). among the microorganisms salmonella typhimurium was the most frequent (25%) followed by klepsiella sp. (21%) and escherichia coli (17%). it was also observed that the main cuase of death was the largest occurrence of salmonella typhimurium and pseudomonas aeruginosa among the isolates. regarding drug r ... | 1975 | 1236053 |
| the treatment of salmonellosis in equidae. | among 23 equidae in which various treatment or management regimens for salmonellosis were observed and evaluated, 9 horses were infected with salmonella typhimurium and 8 with s anatum; an aged mule harbored s newport, and 1 isolant was not identified. four dual sero-type infections occurred: 3 typhimurium/anatum and 1 anatum/newington. the results obtained with various antimicrobials in therapy of peracute, acute, and chronic infections were discouraging or questionable with regard to efficacy ... | 1976 | 1246235 |
| [possible relationship between bacterial surface structures, immune-adherence, chemotaxis and phagocytosis (author's transl)]. | in the present study we attempted to determine the relationship between bacterial surface structures, immune adherence, chemotaxis and phagocytosis. as shown in table 1 encapsulated bacteria (klebsiella ozanae, k. pneumoniae, pasteurella multocida, streptococcus pneumoniae), mycoplasma pneumoniae and m. fermentans had a much lower immune adherence-activity than non-encapsulated bacteria (bacillus cereus, brucella abortus, erysipelothrix insidiosa, escherichia coli, listeria monocytogenes, pseudo ... | 1976 | 1258564 |
| separation of two lipopolysaccharide populations with different contents of o-antigen factor 122 in salmonella enterica serovar typhimurium. | lipopolysaccharide (lps) extraction from smooth-type salmonella enterica sv. typhimurium was carried out with the modified phenol/chloroform/petroleum ether method (volume ratio 5:5:8). in this procedure, lps was precipitated from 90% phenol sequentially with water and acetone to yield lps-h2o (minute amounts) and lps-ac (major amounts), respectively. chemical analyses of the lps fractions revealed that in the o antigen of lps-h2o position c4 of the d-galactose was extensively glucosylated, corr ... | 1992 | 1279361 |
| assessment of the genotoxic potential of riboflavin and lumiflavin. b. effect of light. | on exposure to visible light, riboflavin and lumiflavin produced reactive oxygen species such as singlet oxygen and superoxide radicals. the reaction was found to be time- and concentration-dependent. both riboflavin and lumiflavin, upon illumination, showed mutagenic response in the umu test as well as in the ames/salmonella assay with salmonella typhimurium ta102. the mutagenic response was partially abolished by superoxide dismutase while sodium azide did not have any effect. no mutagenicity ... | 1992 | 1279412 |
| monoclonal antibodies against salmonella porins: generation and characterization. | monoclonal antibodies (mabs) were generated against porins, one of the major outer membrane proteins of salmonella typhi. six clones, designated mp1, mp2, mp3 (igg2ak), mpn4, mpn6 (igg1k) and mpn5 (igg2bk) were characterized by enzyme immunoassay (elisa) for their reactivity to porins from s. typhi, salmonella paratyphi a, s. paratyphi b, s. paratyphi c, salmonella choleraesuis, salmonella enteritidis, salmonella krefeld, salmonella panama, salmonella typhimurium, escherichia coli b, shigella fl ... | 1992 | 1280248 |
| characterization of the salmonella typhimurium phoe gene and development of salmonella-specific dna probes. | in escherichia coli k-12, the phoe gene, encoding a phosphate-limitation-inducible outer membrane pore protein (phoe), is closely linked to the genes proa and prob. when the corresponding fragment of the salmonella typhimurium chromosome was transferred to e. coli k-12 using an rp4::minimu plasmid, pulb113, no production of s. typhimurium phoe could be detected. nevertheless, dna hybridization studies revealed that the corresponding plasmid did contain s. typhimurium phoe. production of s. typhi ... | 1992 | 1280609 |
| mutagenicity testing of protein-containing and biological samples using the ames/salmonella plate incorporation test and the fluctuation test. | mutagenicity testing of biological samples and proteins is complicated by the presence of histidine and histidine-related growth factors which may produce a false positive result in the ames/salmonella plate incorporation test. a bioassay method, utilizing an automated dispenser-photometer and salmonella typhimurium strain ta1535 as the indicator bacteria, was used to estimate the presence of histidine-related growth factors in three enzyme solutions submitted for mutagenicity testing. one of th ... | 1992 | 1281266 |
| inhibitory activity of heat treated vegetables and indigestible polysaccharides on mutagenicity. | the effects of heat treated vegetables on mutagenicity were studied using the salmonella typhimurium system. the mutagens used were 3-amino-1-methyl-5h-pyrido[4,3-b]indole, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide, 4-nitroquinoline-1-oxide, acridine yellow and 2-aminoanthracene. most of the heated vegetables unexpectedly showed greater inhibitory activity against the mutagenicity than unheated samples. the activity was increased markedly by heat treatment of water soluble indigestible polysacch ... | 1992 | 1281271 |
| rat pulmonary microsomal cytochrome p-450 enzymes involved in the activation of procarcinogens. | rat lung microsomal cytochrome p-450 (p-450) enzymes have been characterized with regard to their catalytic specificities towards activation of several procarcinogens to genotoxic metabolites in salmonella typhimurium ta1535/psk1002. we first examined the roles of rat liver microsomal p-450 enzymes in the activation of benzo[a]pyrene and its 7,8-diol enantiomers to genotoxic products, and found that p-450 1a1 is a major catalyst for the activation of these potential procarcinogens in rat livers. ... | 1992 | 1281274 |
| mutagenic activity in wastewater concentrates from dye plants. | wastewater concentrates from the wastewater treatment systems of three dye plants were tested for mutagenic activity in salmonella typhimurium ta98 and escherichia coli wp2uvra using a fluctuation assay. concentrates were prepared by passing samples of wastewater (5-6 or 30 litres) through two porous resins (xad-2 and xad-7) in series. s. typhimurium in the presence of microsomal activation proved to be the more sensitive marker of mutagenicity. mutagenic responses were observed in concentrates ... | 1992 | 1282216 |
| production and epidemiological application of monoclonal antibody specific for salmonella o5-antigen. | salmonella typhimurium is an important causative agent of acute gastroenteritis (food poisoning), and the decision of the source of infection urgently requires epidemiological investigation. there are two types of s. typhimurium, o5-antigen-carrier type (o5(+)-antigen type) and noncarrier type (copenhagen antigen type). on the assumption that serological differentiation of the types is effective for epidemiological exploration for the source of infection, we produced a monoclonal antibody, tmy1, ... | 1992 | 1282581 |
| antigen selection and presentation to protect against transmissible gastroenteritis coronavirus. | the antigenic structure of the s glycoprotein of transmissible gastroenteritis virus (tgev) and porcine respiratory coronavirus (prcv) has been determined and correlated with the physical structure. four antigenic sites have been defined (a, b, c, and d). the sites involved in the neutralization of tgev are: a, d, and b, sites a and d being antigenically dominant for tgev neutralization in vitro. these two sites have specific properties of interest: site a is highly conserved and is present in c ... | 1992 | 1282756 |
| salmonella typhimurium dt 49. | 1992 | 1285117 | |
| salmonella typhimurium dt 203 update. | 1992 | 1285146 | |
| salmonella typhimurium dt 141. | 1992 | 1285151 | |
| salmonella typhimurium dt 203 in west yorkshire. | 1992 | 1285184 | |
| the rigidity of bacterial flagellar filaments and its relation to filament polymorphism. | we determined and correlated the rigidity of salmonella typhimurium, escherichia coli, and rhizobium lupini flagellar filaments representing various structural and polymorphic states (plain, complex, straight, superhelical, and right- and left-handed). persistence length, from which the filament's rigidity and other parameters (young's modulus, bending force constant, buckling persistence length, flexural deformation, and flexural time) were derived, was determined from electron micrographs of i ... | 1992 | 1286007 |
| mutagenicity of analgesics, their derivatives, and anti-inflammatory drugs with s-9 mix of several animal species. | an investigation was undertaken to determine whether analgesics and their derivatives (13 compounds), and anti-inflammatory drugs (4 compounds) had mutagenicity. rec-assay was used to clarify specific dna-damaging properties, and the ames test was used to find back-mutations, using s-9 fractions obtained from the liver of 4 animal species pretreated with polychlorobiphenyl. in the rec-assay, salicylic acid (2 mg), aspirin (5 mg), benzoic acid (4 mg), sulpyrine (0.4 mg), indomethacin (0.1 mg), ox ... | 1992 | 1287147 |
| mg2+ transporting p-type atpases of salmonella typhimurium. wrong way, wrong place enzymes. | 1992 | 1288323 | |
| clavine alkaloids and derivatives as mutagens detected in the ames test. | eight cytostatic clavines were investigated for mutagenicity in salmonella typhimurium (reversion of the his-strains ta98, ta100, ta102 and ta1537), directly and in the presence of a mammalian xenobiotic metabolizing system, s9 (nadph-fortified postmitochondrial fraction of liver homogenate from aroclor 1254-treated rats). four compounds (festuclavine, 17-bromofestuclavine, 1-allylelymoclavine and 1-methyllysergol methyl ether) were direct mutagens, whose activity was enhanced in the presence of ... | 1992 | 1288732 |
| [the survival ability of salmonella, coccidia oocysts and ascarid eggs in laying hen feces from different housing systems]. | the time of survival of salmonella typhimurium, coccidia oocysts and ascaris eggs in manure of layer was determined in 5 different housing systems and 2 storing places for litter. the experiments were carried out in a stable of experimental station frankenforst of the university of bonn with a flock of 2200 hens. the effects of the environment conditions temperature, dry matter content, ph-value and intestinal microflora of the manure have also been studied. the time of survival was different de ... | 1992 | 1289044 |
| a 'safe-site' for salmonella typhimurium is within splenic polymorphonuclear cells. | following oral or systemic infection with salmonella typhimurium, the focus of infection is in the liver and spleen. the majority of salmonella surviving in the liver and spleen by 4 h post infection are already in an environment where they are largely protected from subsequent killing. previous studies have shown that the majority of surviving salmonella are intracellular. in the present study we sought to determine the cell type containing most of the cell-associated salmonella liberated from ... | 1992 | 1291841 |
| [mutagenicity studies of prednisolone farnesylate (pnf)]. | prednisolone farnesylate (pnf) was tested for mutagenicity by ames test using salmonella typhimurium (ta100, ta1535, ta98, ta1537) and escherichia coli (wp2 uvra), for clastogenic activity in vitro by the chromosomal aberration test in a chinese hamster fibroblast cell line (chl), and for induction of micronuclei by the micronucleus test in male icr mice. 1) in ames test, pnf with and without metabolic activation showed no mutagenicity in any strains at any dose levels (312-5,000 micrograms/plat ... | 1992 | 1293327 |
| photolabelling of salmonella typhimurium lt2 sialidase. identification of a peptide with a predicted structural similarity to the active sites of influenza-virus sialidases. | the sialidase from salmonella typhimurium lt2 was characterized by using photoaffinity-labelling techniques. the well-known sialidase inhibitor 5-acetamido-2,6-anhydro-3,5-dideoxy-d-glycero-d-galacto-non- 2-enonic acid (neu5ac2en) was modified to contain an amino group at c-9, which permitted the incorporation of 4-azidosalicylic acid in amide linkage at this position. labelling of the purified protein with the radioactive (125i) photoprobe was determined to be highly specific for a region withi ... | 1992 | 1295492 |
| [the urinary mutagenicity test in monitoring exposure to aromatic polycyclic hydrocarbons in workers in the aluminum industry]. | the sensitivity of 3 urinary mutagenicity tests was assayed: the plate test, the fluctuation test and the micropreincubation test, in order to assess their possible use in monitoring human exposure to polycyclic aromatic hydrocarbons (pah). urine samples from workers of an anode production plant exposed to coal tar and from psoriatic patients undergoing treatment with coal-tar ointments were tested for mutagenic activity on strain ta98 salmonella typhimurium, in the presence of the microsome fra ... | 1992 | 1297066 |
| introduction of francisella tularensis at skin sites induces resistance to infection and generation of protective immunity. | mice are susceptible to systemic infection with francisella tularensis strain lvs; thus, the intraperitoneal (i.p.) lethal dose at 50% (ld50) in c3h/hen and c57bi/6j mice is only a single bacterium, while the intradermal (i.d.) ld50 is more than 10(4). here we show that the ld50 when lvs is introduced via the skin, either i.d. or subcutaneously (s.c.), ranges from 7 x 10(4) to 2 x 10(6). sublethal i.d. or s.c. infection (priming) invariably leads to the generation of systemic and specific protec ... | 1992 | 1297917 |