| overexpression and purification of the separate tryptophan synthase alpha and beta subunits from salmonella typhimurium. | to obtain high levels of expression of the free alpha and beta subunits of tryptophan synthase from salmonella typhimurium, we have used two plasmids (pstrpa and pstrpb) that carry the genes encoding the alpha and beta subunits, respectively. the expression of each plasmid in escherichia coli cb149 results in overproduction of each subunit. we also report new and efficient methods for purifying the individual alpha and beta subunits. microcrystals of the beta subunit are obtained by addition of ... | 1992 | 1422228 |
| the prevalence of salmonella infections in camels (camelus dromedarius) in the united arab emirates. | one hundred and eighty-seven salmonella strains were isolated from 4006 samples collected from camels in the united arab emirates between 1987 and 1991. one hundred and sixty-five (4.3%) strains were isolated from 3801 faecal and 22 from 205 organ samples of 62 autopsied camels. in total, 28 different serotypes were identified with s. saintpaul being the most frequent (69), followed by s. frintrop (31) and s. hindmarsh (15). salmonella typhimurium was isolated from only two faecal specimens. all ... | 1992 | 1422785 |
| effect of caffeic acid esters on carcinogen-induced mutagenicity and human colon adenocarcinoma cell growth. | propolis, a honey bee hive product, is thought to exhibit a broad spectrum of activities including antibiotic, antiviral, anti-inflammatory and tumor growth inhibition; some of the observed biological activities may be due to caffeic acid (cinnamic acid) esters that are present in propolis. in the present study we synthesized three caffeic acid esters, namely methyl caffeate (mc), phenylethyl caffeate (pec) and phenylethyl dimethylcaffeate (pedmc) and tested them against the 3,2'-dimethyl-4-amin ... | 1992 | 1423745 |
| cytochrome p450 2e1 and 2a6 enzymes as major catalysts for metabolic activation of n-nitrosodialkylamines and tobacco-related nitrosamines in human liver microsomes. | an acetyltransferase-overexpressing strain of salmonella typhimurium (nm2009) has been used to investigate roles of human liver microsomal cytochrome p450 (p450) enzymes in the activation of carcinogenic nitrosamine derivatives, including n-nitrosodialkylamines and tobacco-smoke-related nitrosamines, to genotoxic products. studies employing correlation of activities with several p450-dependent monooxygenase reactions in different human liver samples, inhibition of microsomal activities by antibo ... | 1992 | 1423839 |
| response of the ke test to nci/ntp-screened chemicals. iii. complementary value of ke in screening for carcinogens. | the value of using a physico-chemical carcinogen-screening test, the ke test, in conjunction with the salmonella typhimurium/microsome assay (the ames test) and/or structural alerts of reactivity (the s/a test), is analyzed on the basis of the response of the three tests to 171 chemicals of known rodent carcinogenicity. the ames test is widely used to screen chemicals for potential carcinogenicity; however, its relatively low sensitivity (proportion of true positives among carcinogens tested) ha ... | 1992 | 1423876 |
| proteolytic cleavage by neutrophil elastase converts inactive storage proforms to antibacterial bactenecins. | bac5 and bac7, antibiotics of the bactenecin (proline/arginine-rich peptide) family, are stored as proforms in the large granules of bovine neutrophils [zanetti, m., litteri, l., gennaro, r., horstmann, h. and romeo, d. (1990) j. cell biol. 111, 1363-1371]. these proforms have been purified to homogeneity from granule extracts by immunoaffinity and reverse-phase chromatography. while mature bactenecins efficiently kill escherichia coli, klebsiella pneumoniae and salmonella typhimurium with minim ... | 1992 | 1425666 |
| gentisate pathway in salmonella typhimurium: metabolism of m-hydroxybenzoate and gentisate. | salmonella typhimurium was shown to use the gentisate pathway to metabolize m-hydroxybenzoate and gentisate, m-hydroxybenzoate hydroxylase and gentisate 1,2-dioxygenase were induced by growth on either gentisate or m-hydroxybenzoate. these enzymes were not detected when the bacteria were grown with glucose or glucose and either m-hydroxybenzoate or gentisate. however, both enzymes were induced when the bacteria were grown on succinate with either substrate. the maleylpyruvate isomerase required ... | 1992 | 1427003 |
| eight bacterial proteins, including udp-n-acetylglucosamine acyltransferase (lpxa) and three other transferases of escherichia coli, consist of a six-residue periodicity theme. | only a few prokaryotic or eukaryotic enzymes are known to consist of a tandem-repeat structure. this report describes a common hexapeptide-repeat theme in four escherichia coli transferases and in four less-characterized bacterial proteins. the proteins are the ssc protein of salmonella typhimurium (25), udp-n-acetylglucosamine acyltransferase of e. coli (24), the hypothetical proteins tms of bacillus subtilis (23) and yglm of e. coli (22), succinyldiaminopimelate aminotransferase of e. coli (14 ... | 1992 | 1427014 |
| sequence analysis of mutations arising during prolonged starvation of salmonella typhimurium. | we have examined the effects of prolonged histidine deprivation on the reversion of salmonella typhimurium histidine auxotrophs containing either hisg46, a missense mutation (ctc----ccc), or hisg428, an ochre mutation (caa----taa). both of these mutants can revert to his+ via intragenic and extragenic mechanisms. whereas the hisg46 mutant site consists of g/c base pairs, extragenic suppression of hisg46 requires mutation at an a/t site. conversely, the hisg428 site itself contains only a/t base ... | 1992 | 1427030 |
| effect in vitro of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid on the hepatic activation of dietary genotoxins by rat post-mitochondrial fractions. | the effect of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid on the conversion of the heterocyclic amine 2-amino-3-methylimidazo[4,5-f]quinoline (iq) to its genotoxic metabolites was investigated using a modified bacterial mutation assay. the assay used salmonella typhimurium ta98 as an indicator of the mutagenicity and hepatic post-mitochondrial fractions (s-9) from male sprague-dawley rats as the activating system. all three fatty acids inhibited the mutagenicity of iq withou ... | 1992 | 1427507 |
| antimutagenic activity of plumbagin in ames salmonella typhimurium test. | this paper reports the antimutagenic activity of plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone) against certain known chemical mutagens in a standard mutagenicity test system of ames using s. typhimurium strains. plumbagin by itself did not show any mutagenic effect, whereas it reduced significantly the mutagenic effect of 4-nitrophenylene diammine, phenyl hydrazine and sodium azide in test strains of s. typhimurium, suggesting that plumbagin possessed antimutagenic activity. | 1992 | 1428056 |
| chemicals classified by iarc: their potency in tests for carcinogenicity in rodents and their genotoxicity and acute toxicity. | chemicals classified by the iarc to its groups 1, 2a, 2b and 3 were examined in an attempt to identify characteristics of their behaviour in experimental studies of carcinogenicity, genotoxicity and acute mammalian toxicity that correlate with those categories. only those agents for which information on carcinogenic potency was available were studied. in both mice and rats, more chemicals were potent carcinogens if they had been categorized in group 1 (human carcinogens) than if they had been pu ... | 1992 | 1428089 |
| detection of 2-amino-1-methyl-6-(4-hydroxyphenyl)imidazo[4,5-b]pyridine in broiled beef. | 2-amino-1-methyl-6-(4-hydroxyphenyl)imidazo[4,5-b]pyridine (4'-oh-phip) showed mutagenicity in salmonella typhimurium ta98 in the presence of s9 mix, inducing 180 revertants per 100 micrograms. since creatinine, tyrosine and glucose, which are present in meat, are expected to be involved in the formation of 4'-oh-phip, its presence in broiled beef was examined. 4'-oh-phip was detected in broiled beef by high-performance liquid chromatography and uv-spectrometry after extraction with 0.1 n hcl an ... | 1992 | 1429200 |
| mutants carrying conditionally lethal mutations in outer membrane genes omsa and fira (ssc) are phenotypically similar, and omsa is allelic to fira. | we have previously identified the gene (the ssc gene) defective in the thermosensitive and antibiotic-supersusceptible outer membrane permeability mutant ss-c of salmonella typhimurium and shown that this gene is analogous to the escherichia coli gene fira (l. hirvas, p. koski, and m. vaara, embo j. 10:1017-1023, 1991). others have tentatively implicated fira in a different function, mrna synthesis. here we report that the defect in the thermosensitive outer membrane omsa mutant of e. coli (t. t ... | 1992 | 1429432 |
| nucleotide sequences and characterization of liv genes encoding components of the high-affinity branched-chain amino acid transport system in salmonella typhimurium. | a 7.6-kb fragment of salmonella typhimurium lt2 containing the liv gene cluster, which specifies the high-affinity branched-chain amino acid transport system (liv-i), has been isolated. the upstream region contains the livb and livc genes encoding the leucine-isoleucine-valine-threonine and leucine-specific binding proteins, respectively. in this study, the nucleotide sequence of the 4-kb downstream segment was determined and found to contain four reading frames, designated as liva, live, livf, ... | 1992 | 1429514 |
| site-specific frameshift mutagenesis by a propanodeoxyguanosine adduct positioned in the (cpg)4 hot-spot of salmonella typhimurium hisd3052 carried on an m13 vector. | malondialdehyde induces frameshift mutations in salmonella typhimurium strain hisd3052. the ability of propanodeoxyguanosine (pdg), a structural analog of the major malondialdehyde-deoxyguanosine adduct, to induce site-specific frameshift mutations was tested in the (cpg)4 hot-spot of hisd3052 carried on an m13 vector (m13mb102). pdg was introduced at position 6248 of duplex m13mb102 by ligation of the oligonucleotide 5'-cgc(pdg)cggcatg-3' into a heteroduplex containing an 11-nucleotide gap in t ... | 1992 | 1429591 |
| use of the lipid emulsion system and salmonella typhimurium mitogen adjuvant to stimulate igg production in chickens. | chickens were immunized with the lipid emulsion system and salmonella typhimurium mitogen adjuvant for fowl plus synthetic peptides corresponding to the divergent amino acid sequences at the carboxyl terminus of each of two different alpha-tubulin isoforms from arabidopsis thaliana. antibodies were extracted from egg yolks and used in immunoblot assays to determine the time course of antibody production in two chickens. specific immunoglobulin production increased 10-14 days after the primary in ... | 1992 | 1431155 |
| the effects of interferon-gamma and bacterial lipopolysaccharide on cd14 expression in human monocytes. | cd14 has been reported to be the lipopolysaccharide (lps)-lps binding protein receptor. the effects of interferon-gamma (ifn-gamma) on cd14 expression have not been clearly established. the purpose of this investigation was to examine the effects of ifn-gamma alone and ifn-gamma followed by bacterial lps on cd14 expression. human peripheral blood monocytes were isolated by counterflow centrifugal elutriation (cce). monocytes were cultured for 48 h with ifn-gamma alone or for 24 h with ifn-gamma ... | 1992 | 1431309 |
| [antimutagenic activities of hexane extracts of the fruit extract and the kernels of prunus mume sieb. et zucc]. | antimutagenic activities of hexane extracts obtained from the fruit extract (ue) and the kernels (ke) of p. mume were examined. these extracts showed inhibitory activities to known mutagens, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide, benzo[alpha]pyrene and aflatoxin b1 in the ames assay using salmonella typhimurium ta100 and ta98 strains. the ue and ke fractions were then separated by silicic acid column chromatography with a stepwise elution method using ether-hexane. the location of the active ... | 1992 | 1432606 |
| molecular characterization of r-plasmids pst1 and pst2 from salmonella typhimurium s24. | salmonella typhimurium s24 was isolated in september 1986 at kaohsiung medical college hospital, kaohsiung, taiwan, from a patient suffering from gastroenteritis during an outbreak of salmonellosis. two conjugative r-plasmids have been isolated from escherichia coli k-12 14r525, which was mated with s. typhimurium s24. the two r-plasmids found in s. typhimurium s24 belong to two different incompatibility (inc) groups: the 130-kilobase incfi plasmid pst1 and the 56-kb incn plasmid pst2. these two ... | 1992 | 1433439 |
| the molecular basis for positive regulation of cys promoters in salmonella typhimurium and escherichia coli. | most genes required for cysteine biosynthesis in salmonella typhimurium and escherichia coli are positively regulated by cysb, which encodes a transcriptional activator belonging to the lysr family of regulatory proteins. cysb protein binds just upstream of the -35 region of positively regulated promoters, where in the presence of inducer it facilitates formation of a transcription initiation complex. cysb protein also autoregulates its own synthesis by binding to the cysb promoter as a represso ... | 1992 | 1435253 |
| effect of ethylenediamine di-o-hydroxyphenylacetic acid and transferrin on the growth of some bacterial strains in vitro. | the ability of some bacterial strains to obtain iron from ethylenediamine di-o-hydroxyphenylacetic acid (edda) or iron-free transferrin, and accordingly grow in their presence, was studied. growth of staphylococcus aureus and yersinia pseudotuberculosis was inhibited by edda or by iron-free transferrin. growth of streptococcus faecalis, however, was inhibited by iron-free transferrin, but not by edda. the other bacterial strains, i.e.; escherichia coli, salmonella typhimurium and shigella dysent ... | 1992 | 1435350 |
| antimutagenic and anticarcinogenic effects of carotenoids and dietary palm oil. | four carotenoids, canthaxanthin, beta-carotene, 8h-apo-beta-carotenal, and 8'-apo-beta-carotene methylester were tested for their ability to suppress the mutagenicity of 1-methyl-3-nitro-1-nitrosoguanidine and benzo[a]pyrene (bp) in salmonella typhimurium tester strain ta 100. the anticarcinogenic efficacy of the four carotenoids was further assessed in the bp-induced forestomach tumor model in female swiss mice. the effect of dietary palm oil was also examined in bp-induced neoplasia in the fem ... | 1992 | 1437647 |
| mutagenicity of crude senna and senna glycosides in salmonella typhimurium. | the mutagenicity of senna glycosides and extracts of senna folium and senna fructus was investigated in the salmonella typhimurium reversion assay. senna glycosides were inactive in all strains, except for a slight, but significant increase in mutant frequency in ta102 in the absence and presence of liver microsomes. extracts of senna fructus and senna folium demonstrated weak activity in ta97a, ta100 and ta102 in the presence of liver microsomes, and in ta97a and ta102 in the absence of liver m ... | 1992 | 1438037 |
| salmonella typhimurium activates virulence gene transcription within acidified macrophage phagosomes. | survival of salmonella typhimurium within macrophage phagosomes requires the coordinate expression of bacterial gene products. this report examines the contribution of phagosomal ph as a signal for expression of genes positively regulated by the s. typhimurium virulence regulators phop and phoq. several hours after bacterial phagocytosis by murine bone marrow-derived macrophages, phop-activated gene transcription increased 50- to 77-fold. in contrast, no difference in phop-activated gene express ... | 1992 | 1438196 |
| persistent salmonella typhimurium pt 104 infection in a dairy herd. | | 1992 | 1441160 |
| bacterial metabolism of 2,6-dinitrotoluene with salmonella typhimurium and mutagenicity of the metabolites of 2,6-dinitrotoluene and related compounds. | 1. metabolites produced by the incubation of 2,6-dinitrotoluene (2,6-dnt) with salmonella typhimurium strains ta 98, ta 98/1,8-dnp6 and ta 98nr were examined. mutagenicities of bacterial products and related compounds were also examined in the ames assay using ta 98 and ta 100. 2. 2,6-dnt was converted to 2-nitroso-6-nitrotoluene, 2-hydroxylamino-6-nitrotoluene and 2-amino-6-nitrotoluene, with concurrent spontaneous formation of 2,2'-dimethyl-3,3'-dinitroazoxybenzene, in the incubation with ta 9 ... | 1992 | 1441587 |
| a study of inactivation reactions of n-acetylcysteine with mucochloric acid, a mutagenic product of the chlorination of humic substances in water. | the salmonella typhimurium (ta100) mutagenic compound, mucochloric acid [3,4-dichloro-5-hydroxy-2(5h)-furanone (mca)], was inactivated by in vitro n-acetylcysteine (nac). the reaction of mca with nac at ph7 was second order and gave products 4, 5, and 6a that resulted from the displacement of chlorine from c-3 or c-4 of mca. the sodium borohydride treatment of product 4 gave the same product (7) as was obtained by treating 3,4-dichloro-2(5h)-furanone with nac. the treatment of mca with (r)-(+)-c ... | 1992 | 1446000 |
| [dependence of mutagenic activity of heterocyclic analogs of pyrene on their chemical structure]. | comparative mutagenic activity of 6 heterocyclic analogs of pyrene was studied. the highest activity was revealed for 2,7-dinitro-4,9-dioxy-5,10-dioxo-4,5,9,10-tetrahydro-4,9- diazapyrene (2,7-dn-ddtdp) and 2,7-dinitro-5,10-dioxo-4,9-dioxapyrene (2,7-dn-ddp) which induced mutations in the tester strain salmonella typhimurium ta98 and ta100. high mutagenicity of 2,7-dn-ddtdp and 2,7-dn-ddp is conditioned by reduction of nitro groups in the 2,7 position. the carbonyl groups in the 5,10 position we ... | 1992 | 1446814 |
| characterization of a high-affinity iron transport system in acinetobacter baumannii. | analysis of a clinical isolate of acinetobacter baumannii showed that this bacterium was able to grow under iron-limiting conditions, using chemically defined growth media containing different iron chelators such as human transferrin, ethylenediaminedi-(o-hydroxyphenyl)acetic acid, nitrilotriacetic acid, and 2,2'-bipyridyl. this iron uptake-proficient phenotype was due to the synthesis and secretion of a catechol-type siderophore compound. utilization bioassays using the salmonella typhimurium i ... | 1992 | 1447137 |
| cloning and sequencing of a gene encoding a 21-kilodalton outer membrane protein from bordetella avium and expression of the gene in salmonella typhimurium. | three gene libraries of bordetella avium 197 dna were prepared in escherichia coli le392 by using the cosmid vectors pcp13 and pya2329, a derivative of pcp13 specifying spectinomycin resistance. the cosmid libraries were screened with convalescent-phase anti-b. avium turkey sera and polyclonal rabbit antisera against b. avium 197 outer membrane proteins. one e. coli recombinant clone produced a 56-kda protein which reacted with convalescent-phase serum from a turkey infected with b. avium 197. i ... | 1992 | 1447140 |
| mutagenicity evaluation of riot control agent o-chlorobenzylidene malononitrile (cs) in the ames salmonella/microsome test. | o-chlorobenzylidene malononitrile (cs), a riot control agent, was evaluated for its possible mutagenic activity in the ames salmonella/mammalian microsome mutagenicity test. five histidine-deficient (his-) mutant tester strains of salmonella typhimurium--ta97a, ta98, ta100, ta102 and ta104--were used. the liquid preincubation procedure was used with metabolic activation (presence of s9 mixture) and without metabolic activation (absence of s9 mixture). for the experiments with metabolic activatio ... | 1992 | 1447485 |
| identification and sequence of a na(+)-linked gene from the marine bacterium alteromonas haloplanktis which functionally complements the daga gene of escherichia coli. | a 4.0 kb fragment from a plasmid genomic dna library of the marine bacterium alteromonas haloplanktis atcc 19855 was found in the presence of na+ to complement the daga gene of escherichia coli. we have completely sequenced this fragment and the position of the na(+)-linked d-alanine glycine permease gene (daga) on the fragment has been determined by complementation. the predicted carrier protein consists of 542 amino acid residues (m(r) 58,955). its hydropathy profile suggests it is composed of ... | 1992 | 1447975 |
| identification and characterization of fliy, a novel component of the bacillus subtilis flagellar switch complex. | the bacillus subtilis gene encoding fliy has been cloned and sequenced. the gene encodes a 379-amino-acid protein with a predicted molecular mass of 41,054 daltons. fliy is partly homologous to the escherichia coli and salmonella typhimurium switch proteins flim and flin. the n-terminus of fliy has 33% identity with the first 122 amino acids of flim, whereas the c-terminus of fliy has 52% identity with the last 30 amino acids of flin. the middle 60% of fliy is not significantly homologous to eit ... | 1992 | 1447979 |
| cloning and characterization of a neisseria gene homologous to hisj and argt of escherichia coli and salmonella typhimurium. | we have isolated from a genomic library of the pathogenic neisseriae gonorrhoeae t2 strain, a gene encoding a putative protein of 268 amino acids which exhibited significant similarity to the hisj and argt gene products of salmonella typhimurium and escherichia coli, periplasmic proteins deputed to amino acid transport within the cell. the gene is transcribed as a monocistronic mrna species of about 960 nucleotides flanked by regulatory elements for initiation and termination of transcription th ... | 1992 | 1448614 |
| conserved structural and regulatory regions in the salmonella typhimurium btub gene for the outer membrane vitamin b12 transport protein. | the salmonella typhimurium btub gene encodes an outer membrane protein that is necessary for the transport of vitamin b12 and the uptake of the e colicins and bacteriophage bf23. the sequence of this gene showed 87% identity of the deduced polypeptide to its escherichia coli homolog, and its product was found to function in transport as effectively in cells of e. coli as did the native protein. the extensive sequence conservation within the first 300 transcribed nucleotides, which include the le ... | 1992 | 1448622 |
| expression of 9 salmonella typhimurium enzymes for cobinamide synthesis. identification of the 11-methyl and 20-methyl transferases of corrin biosynthesis. | nine of the cbi genes from the 17.5 kb cob operon of salmonella typhimurium previously shown by genetic studies to be involved in the biosynthesis of cobinamide from precorrin-2, have been subcloned and expressed in escherichia coli. seven of the gene products were found in the soluble fraction of cell lysates and have been purified. the gene products corresponding to cbi e, f, h and l were shown by sam binding and by homology with other sam-binding proteins to be candidates for the methyltransf ... | 1992 | 1451790 |
| fine structure mapping and complementation studies of the metd methionine transport system in salmonella typhimurium. | a fine structure deletion map of the metd region of the chromosome of salmonella typhimurium responsible for a high-affinity methionine transport system has been constructed. complementation tests involving the introduction of metd+dna contained in a puc8 vector into metd strains indicated the presence of four complementation groups in the metd region. this suggested that the methionine system belongs to the osmotic shock-sensitive class of transport system, and therefore should possess a peripl ... | 1992 | 1452012 |
| identification of p60 antibodies in human sera and presentation of this listerial antigen on the surface of attenuated salmonellae by the hlyb-hlyd secretion system. | antibodies directed against the major secreted protein of listeria monocytogenes, termed p60, were found more frequently than antilisteriolysin antibodies in sera of listeriosis patients. anti-p60 antibodies were also identified in all tested sera from healthy individuals. to test whether p60 provides protection against l. monocytogenes, we constructed an attenuated salmonella typhimurium aroa strain which secretes p60 via the escherichia coli hemolysin secretion pathway. application of this sal ... | 1992 | 1452342 |
| early pathogenesis of infection in the liver with the facultative intracellular bacteria listeria monocytogenes, francisella tularensis, and salmonella typhimurium involves lysis of infected hepatocytes by leukocytes. | the results show that listeria monocytogenes, francisella tularensis, and salmonella typhimurium are facultative intracellular bacteria with a capacity to invade and grow in nonphagocytic cells in vivo. in the liver, all of these pathogens were seen to invade and to multiply extensively in hepatocytes. in all three cases, inflammatory phagocytes were rapidly marshalled to foci of infection where they appeared to cause the destruction of infected hepatocytes, thereby releasing bacteria into the e ... | 1992 | 1452350 |
| studies on antimutagenic effect of milk cultured with lactic acid bacteria on the trp-p2-induced mutagenicity to ta98 strain of salmonella typhimurium. | the inhibitory effects of cultured milk using 76 strains of lactic acid bacteria isolated from milk products were investigated on the mutagenicity of 3-amino-1-methyl-5h-pyrido[4,3-b]indole (trp-p2), a tryptophan pyrolysate for salmonella typhimurium ta98. each cultured milk sample displayed its characteristic antimutagenic effect against the mutagenicity of trp-p2. the milk cultured with lactobacillus acidophilus la106 (la2) showed the highest inhibition of 82.1% among the strains used. milk sa ... | 1992 | 1452836 |
| production of an electrolyte beverage from milk permeate. | the objective of this study was to prepare shelf-stable electrolyte beverages from milk permeate. the average composition of permeate was 4.59% total solids and .40% ash. lactose was hydrolyzed (approximately 80%) with a commercial fungal lactase enzyme. additional sweetness was provided by sucrose. the ph was reduced to 3.5 to 3.8 by the addition of citric acid. shelf-stable products were made using four processes: 1) uht followed by aseptic filling, 2) heating of filled bottles to 85 degrees c ... | 1992 | 1452842 |
| prevention of immunologic stress contributes to the growth-permitting ability of dietary antibiotics in chicks. | the growth-permitting ability of antibiotics fed to broiler chicks was studied as it relates to the state of activation of the immune system. in experiment 1, chicks were fed two levels of antibiotics (0 or 100 mg streptomycin + 100 mg penicillin/kg diet) and were raised either in an environment with poor sanitation to create a chronic immune stress or in a clean environment. chicks raised in the unsanitary environment and not fed antibiotics had significantly lower (p < 0.05) rates of weight ga ... | 1992 | 1453223 |
| expression and characterization of the cloned salmonella typhimurium enterotoxin. | earlier, our laboratory reported the cloning of a chromosomally encoded cholera toxin (ct)-like enterotoxin gene from salmonella typhimurium q1 into pbr322. cell lysates from the plasmid clone pc1, containing a 4.8 kb ecor1 dna fragment from salmonella, caused elongation of chinese hamster ovary (cho) cells and this biologic activity was neutralized by anti-ct. however, this cloned gene product did not elicit fluid secretion in the rabbit intestinal loop (ril) model, because of poor expression. ... | 1992 | 1453924 |
| growth phase and spvr regulation of transcription of salmonella typhimurium spvabc virulence genes. | the 90 kb virulence plasmid of salmonella typhimurium is required for bacterial growth beyond the small intestine to deeper tissues such as the spleen and liver of orally inoculated mice. we constructed transcriptional lacz fusions within the cloned plasmid-borne virulence genes spva, spvb and spvc of s. typhimurium to demonstrate that spvr encodes a trans-acting positive regulator for the transcription of spva, spvb and spvc. data suggesting that the activation of spvabc transcription is depend ... | 1992 | 1453926 |
| a novel transcriptional regulation mechanism in the flagellar regulon of salmonella typhimurium: an antisigma factor inhibits the activity of the flagellum-specific sigma factor, sigma f. | we have studied the molecular mechanism of the negative regulation by flgm of the late operons of the flagellar regulon of salmonella typhimurium. a 7.8 kda protein that was identified as the flgm gene product was purified to homogeneity; its amino-terminal sequence was identical to the deduced sequence except for the lack of the initiating methionine. the purified flgm repressed transcription from the flic promoter, one that is activated by the sigma factor, flia (sigma f). no dna-binding activ ... | 1992 | 1453955 |
| research note: in ovo administration of a competitive exclusion culture treatment to broiler embryos. | exposure of chicks to salmonellae in the hatchery and hatchery environment limits the effectiveness of a competitive exclusion (ce) culture treatment. therefore, in an attempt to apply treatment before chicks are exposed to salmonellae, the ce culture was introduced in ovo to unhatched embryos. an undefined, anaerobically grown ce culture, derived from cecal contents of healthy adult chickens, was diluted 1:1,000 or 1:1,000,000 and inoculated either into the air cell or beneath the inner air cel ... | 1992 | 1454695 |
| antibacterial activity and mutagenicity studies of water-soluble phosphazene high polymers. | eight water-soluble phosphazene high polymers, [npr2]n (r, organic, water-solubilizing side-group; n, approx: 15,000) and the small-molecule counterparts of the polymers were examined for antibacterial activity against six different strains of bacteria (escherichia coli, salmonella typhimurium (ta 100), salmonella pullorum, streptococcus faecalis, bacillus subtilis and pseudomonas aeruginosa). antibacterial testing was carried out by measuring zones of inhibition and changes in solution turbidit ... | 1992 | 1457679 |
| bacterial mutagenicity of extracts of the baked and raw agaricus bisporus mushroom. | aqueous extracts of baked and raw agaricus bisporus (ab) mushroom were tested for mutagenic activity in salmonella typhimurium strains ta1535 and ta1537. the extracts were studied with and without metabolic activation by aroclor-induced rat liver s9 mix. the extracts of the baked and raw ab exhibited a dose related mutagenic activity with and without activation in strain ta1535. similar findings were obtained in strain ta1537, although the net revertant values were of lower magnitude. because hu ... | 1992 | 1457740 |
| identification of salmonella typhimurium invasiveness loci. | salmonella typhimurium is capable of entering into (invading) nonphagocytic host cells. to systematically identify the bacterial genes necessary for this process, 15,000 tn10dcm random transposon mutants of s. typhimurium were individually screened for invasiveness, using the human colonic epithelial caco-2 cell line. four hundred and eighty-eight mutants had decreased levels of invasiveness; most were nonmotile. however, five mutants, representing four loci, were completely motile. further char ... | 1992 | 1458375 |
| siderophores and related outer membrane proteins produced by pseudomonads isolated from eels and freshwater. | a total of 46 environmental pseudomonads, together with six type strains, were examined for their siderophore-producing activity. all strains were able to grow under iron-limiting conditions, gave orange halos in the cas agar assay, and produced hydroxamates, and some of them also produced phenolate-type compounds. bioassays showed that all strains, except pseudomonas aeruginosa, promoted growth of mutant strain arthrobacter flavescens jg-9, deficient in hydroxamate production, and some of them ... | 1992 | 1459416 |
| phosphate starvation affects the synthesis of outer membrane proteins in thiobacillus ferrooxidans. | the outer membrane protein (omp40) component from the chemolithoautotrophic acidophilic thiobacillus ferrooxidans is apparently regulated by the external ph and the concentration of phosphorus. its amino-terminal sequence showed little identity with the escherichia coli ompc, ompf or phoe porins, but was 38.5% identical to the outer membrane channel-forming protein nosa from pseudomonas stutzeri, whose expression is also regulated environmentally. in addition, the partial amino acid sequence of ... | 1992 | 1459418 |
| isolation and characterization of two saccharomyces cerevisiae genes encoding homologs of the bacterial hexa and muts mismatch repair proteins. | homologs of the escherichia coli (mutl, s and uvrd) and streptococcus pneumoniae (hexa, b) genes involved in mismatch repair are known in several distantly related organisms. degenerate oligonucleotide primers based on conserved regions of e. coli muts protein and its homologs from salmonella typhimurium, s. pneumoniae and human were used in the polymerase chain reaction (pcr) to amplify and clone muts/hexa homologs from saccharomyces cerevisiae. two dna sequences were amplified whose deduced am ... | 1992 | 1459447 |
| antimutagenic activity of terminalia chebula (myroblan) in salmonella typhimurium. | antimutagenicity of water and chloroform extracts of dried myroblan terminalia chebula was determined against two direct acting mutagens, sodium azide and 4-nitro-o-phenylenediamine (npd) in strains ta100 and ta1535, and ta97a and ta98 of salmonella typhimurium respectively and s9-dependent mutagen 2-aminofluorene (2-af) in ta97a, ta98 and ta100 strains. water extract reduced npd as well as 2-af induced his+ revertants significantly but did not have any perceptible effect against sodium azide in ... | 1992 | 1459604 |
| combined effects of synthetic lipid a analogs or bacterial lipopolysaccharide with glucosaminylmuramyl dipeptide on antitumor activity against meth a fibrosarcoma in mice. | the combined effects of the synthetic glucosaminylmuramyl dipeptide (gmdp) on the antitumor activity of chemically synthesized lipid a analogs, compound a-103 (glucosamine-4-phosphate with (r)-3-tetradecanoyloxytetradecanoyl group at the c-2 and c-3 positions), escherichia coli-type lipid a (506), salmonella typhimurium lt-2 lipopolysaccharide (lps) against meth a fibrosarcoma in mice were examined. meth a fibrosarcoma cells (5 x 10(5) were inoculated intradermally into balb/c mice on day 0, and ... | 1992 | 1464473 |
| resistance to host antimicrobial peptides is necessary for salmonella virulence. | the production of antibacterial peptides is a host defense strategy used by various species, including mammals, amphibians, and insects. successful pathogens, such as the facultative intracellular bacterium salmonella typhimurium, have evolved resistance mechanisms to this ubiquitous type of host defense. to identify the genes required for resistance to host peptides, we isolated a library of 20,000 mudj transposon insertion mutants of a virulent peptide-resistant s. typhimurium strain and scree ... | 1992 | 1465423 |
| [the evaluation of the mutagenic activity of pertussis vaccinal preparations]. | two vaccine preparations obtained from bordetella pertussis, whole-cell vaccine constituting one of the components of adsorbed dpt vaccine and acellular vaccine, were tested for mutagenicity. the doses of the preparations covered the range 1-100 ed50. ames' test and the metaphase analysis of marrow cells of c57bl/6j mice were used. the acellular preparation was also tested on thymectomized mice, taking into consideration chromosomal aberrations in marrow metaphases. whole-cell and acellular pert ... | 1992 | 1466172 |
| [isolation of vitamin b2 auxotroph and preliminary genetic mapping in salmonella typhimurium]. | the first independent vitamin b2 auxotrophs of salmonella typhimurium were obtained by using selective medium containing extraordinarily high concentration of b2 (300 micrograms/ml) after mutagenesis. transduction analysis showed that 21 b2 auxotrophs could be divided into four groups, which were unlinked to each other. it means that at least 4 structural genes were involved in b2 biosynthetic pathway. preliminary genetic mapping indicated that 2 genes located in 7'-22' and other 2 located in 22 ... | 1992 | 1466913 |
| the macrophage-activating properties of growth hormone. | 1. we compared the ability of growth hormone (gh) and a well-characterized macrophage-activating factor, interferon-gamma (ifn-gamma) to activate highly purified populations of alveolar macrophages. both gh and ifn-gamma primed macrophages triggered with opsonized zymosan to secrete superoxide anion (o2-) in vitro, but ifn-gamma was effective at a 40-fold lower concentration. antibody blocking studies demonstrated that the priming activity of gh was independent of ifn-gamma, and the activity of ... | 1992 | 1468117 |
| the relationship between infecting dose and severity of disease in reported outbreaks of salmonella infections. | the relationship between size of the infecting dose and severity of the resulting disease has been investigated for salmonella infections by reanalysis of data within epidemics for 32 outbreaks, and comparing data between outbreaks for 68 typhoid epidemics and 49 food-poisoning outbreaks due to salmonellas. attack rate, incubation period, amount of infected food consumed and type of vehicle are used as proxy measures of infecting dose, while case fatality rates for typhoid and case hospitalizati ... | 1992 | 1468522 |
| chromosome and sister-chromatid exchange analysis in peripheral lymphocytes, and mutagenicity of urine in anesthesiology personnel. | genotoxic effects of occupational exposure to anesthetic gases (halothane and nitrous oxide) were studied in 24 persons working at departments of anesthesiology and resuscitation (14 anesthesiologists and 10 anesthesiologic nurses). frequencies of chromosomal aberrations were determined in 48-h cultures, and sister-chromatid exchanges (sces) in 72-h cultures of peripheral lymphocytes. in parallel, the mutagenetic potential of urine was tested using ames tester salmonella typhimurium strains ta98 ... | 1992 | 1468800 |
| relationships between in vitro mutagenicity assays. | this paper analyzes the mutagenicity results reported by the us national toxicology program (ntp), relative to 41 chemicals assayed with four in vitro short-term tests [salmonella typhimurium (sty), chromosomal aberrations in chinese hamster ovary (cho) cells (cha), sister chromatid exchange in cho cells (sce), mutation in l5178y mouse lymphoma cells (mly)] and puts this database in perspective with respect to other databases. it is shown that the test relationships pointed out by the experiment ... | 1992 | 1470028 |
| metsovo-tremolite asbestos fibres: in vitro effects on mutation, chromosome aberration, cell transformation and intercellular communication. | samples of metsovo-tremolite asbestos, previously found to be the causative agent of endemic pleural calcification and an increased level of malignant pleural mesothelioma in a rural area of north-western greece (metsovo area), were tested in various in vitro toxicity test systems. it was found that asbestos fibres of this type were strong inducers of micronuclei and numerical chromosomal abnormalities while they induced low levels of chromosomal aberrations in mammalian cells in culture. furthe ... | 1992 | 1470029 |
| effect of anaerobic cecal microflora and dietary lactose on salmonella colonization in bobwhite quail (colinus virginianus). | the effect of oral inoculation with anaerobic cultures of cecal microflora from adult broiler chickens and dietary lactose on salmonella typhimurium cecal colonization was evaluated in bobwhite quail chicks. one-day-old chicks were divided into four groups and provided 1) no anaerobic cultures, no lactose (control); 2) anaerobic cultures; 3) 2.5% lactose (wt/vol) in drinking water; or 4) anaerobic cultures and lactose. all groups were challenged orally with 10(4) s. typhimurium at 2 days of age. ... | 1992 | 1470587 |
| isolation and kinetic properties of acetohydroxy acid isomeroreductase from spinach (spinacia oleracea) chloroplasts overexpressed in escherichia coli. | acetohydroxy acid isomeroreductase catalyses a two-step reaction, an alkyl migration and a nadph-dependent reduction, in the assembly of the carbon skeletons of branched-chain amino acids. detailed investigations of acetohydroxy acid isomeroreductase aimed at elucidating the biosynthetic pathway of branched-chain amino acids and at designing new inhibitors of the enzyme having herbicidal potency have so far been conducted with the enzymes isolated from bacteria. to gain more information on a pla ... | 1992 | 1472001 |
| the bioactivation of 5-(aziridin-1-yl)-2,4-dinitrobenzamide (cb1954)--i. purification and properties of a nitroreductase enzyme from escherichia coli--a potential enzyme for antibody-directed enzyme prodrug therapy (adept). | a nitroreductase enzyme has been isolated from escherichia coli b. this enzyme is an fmn-containing flavoprotein with a molecular mass of 24 kda and requires either nadh or nadph as a cofactor. partial protein sequence analysis showed extensive homology with the "classical nitroreductase" of salmonella typhimurium and a nitroreductase induced in enterobacter cloacae. in common with the salmonella enzyme, the e. coli b enzyme is capable of reducing nitrofurazone. the e. coli nitroreductase is als ... | 1992 | 1472094 |
| salmonella typhimurium lung abscesses in an hiv-infected patient: successful treatment with oral ciprofloxacin. | | 1992 | 1472346 |
| n-hydroxy-meiqx is the major microsomal oxidation product of the dietary carcinogen meiqx with human liver. | 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (meiqx), one of the most abundant of the heterocyclic aromatic amines formed during the cooking of meat, is genotoxic and carcinogenic in rodents. meiqx requires metabolic activation by p450 before it can exert these effects. whilst there is indirect evidence that the mutagenic product is n-hydroxy-meiqx (n-ohmeiqx), we have now identified this unequivocally following incubation of the amine with human hepatic microsomal fraction. a mixture of unlabe ... | 1992 | 1473228 |
| substances in human urine that strongly inhibit bacterial mutagenicity of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) and related heterocyclic amines. | extracts of human urine were shown to contain substances that strongly inhibited the liver s9-mediated mutagenicity of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) in salmonella typhimurium ta98 strain in a liquid incubation assay. the inhibitory effect was unrelated to cytotoxicity and was similar with urine extracts from smokers and non-smokers. under similar assay conditions, the mutagenicity of the related amino-imidazoazaarenes, 2-amino-3-methyl-imidazo[4,5-f]quinoline, 2-amino-3, ... | 1992 | 1473240 |
| organization and ordered expression of caulobacter genes encoding flagellar basal body rod and ring proteins. | the biogenesis of the polar flagellum in caulobacter crescentus is limited to a specific time in the cell cycle and to a specific site on the cell. the basal body is the first part of the flagellum to be assembled. in this report we identify a cluster of genes encoding basal body components and describe their transcriptional regulation. the genes in this cluster form an operon whose expression is controlled temporally. the first two genes encode homologs of flgf and flgg, which are the proximal ... | 1992 | 1474584 |
| genotoxicity of tauromustine, a new water soluble taurine-based nitrosourea. i. mutagenic and clastogenic activity of tauromustine in vitro. | tauromustine (tcnu) a new taurine-based nitrosourea in phase iii clinical trials against colon cancer, has been tested and compared with 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (ccnu) for mutagenic potential in salmonella typhimurium ta98 and ta100 and, for its ability to cause chromosome aberrations and sister chromatid exchanges (sce) in human lymphocytes. a dose dependent increase in the number of mutations in s. typhimurium ta100 but not in ta98 was found from 1.6 to 1000 micr ... | 1992 | 1474918 |
| clastogenicity to the mouse bone marrow of the mouse germ cell genotoxin streptozotocin. | the methylating agent streptozotocin is active in the mouse bone marrow micronucleus assay following a single intraperitoneal injection of 150-180 mg/kg. this correlates with its previously reported toxicity to mouse germ cells when administered by the same route of exposure. the potent mutagenicity of streptozotocin to strain g46 of salmonella typhimurium is compared with its much weaker activity in strain ta1535. the genotoxicity of streptozotocin in vivo is reviewed. | 1992 | 1474923 |
| aspects of tuberculosis in africa. 2. the value of microbiology in the management of tuberculosis in nairobi, kenya. | a group of african patients with tuberculosis were followed over the first month of treatment to assess the bactericidal response to 2 treatment regimens (streptomycin/thiacetazone/isoniazid and streptomycin/rifampicin/isoniazid/pyrazinamide). patients also infected with human immunodeficiency virus (hiv) had lower pre-treatment counts of viable mycobacterium tuberculosis and a greater proportion became culture-negative by 28 d. the response to therapy in hiv positive and hiv negative patients w ... | 1992 | 1475805 |
| some aspects of the epidemiology and control of salmonella typhimurium infection in outwintered suckler cows. | two outbreaks of salmonella typhimurium infections affected outwintered, spring-calving suckler cows in late pregnancy. the infections spread rapidly both within and between groups of stock on the affected farms, with morbidity in the infected groups varying from 14.5 per cent to over 60 per cent, and mortality in adult cattle varying from 0 to 14.3 per cent. prophylactic measures included the use of antibiotics and killed vaccines against escherichia coli, salmonella dublin, s typhimurium, and ... | 1992 | 1475896 |
| immune response of pigs to parenteral vaccination with an aromatic-dependent mutant of salmonella typhimurium. | cellular and humoral immune responses to parenteral vaccination with an aromatic-defined (aroa) salmonella typhimurium and to oral challenge with the s. typhimurium parent strain were examined in pigs. the effectiveness of aroa s. typhimurium vaccination for prevention of clinical disease following challenge was also evaluated. a split litter model was utilized and analysis of variance was by least squares. the statistical model accounted for the effects of vaccination and litter. parenteral vac ... | 1992 | 1477798 |
| antimutagenic agents from natural products. | certain secondary metabolites found in terrestrial and marine plants and organisms have evinced the capability for inhibiting the mutagenicity toward salmonella typhimurium of a number of mutagens. these include 2-aminoanthracene (2an), ethylmethanesulfonate (ems), and benzo-[a]pyrene(b[alpha]p). the sensitivity of the antimutagenicity assay is such that crude extracts can be evaluated and purification of extracts readily followed. major classes of antimutagenic compounds that have been isolated ... | 1992 | 1479376 |
| [protection from virulent salmonella groups b and d after the peroral immunization of chicks with a hybrid of salmonella typhimurium and salmonella dublin]. | chickens over 10 days old, infected orally with virulent salmonellae, were found to remain alive. histologic investigation showed the development of mild enteritis and more pronounced, lasting for more than two weeks, inflammation of the cecum, dissemination and focal lesions in the liver (granulomas, necrosis). in experiments on the oral immunization of 3-day old chickens the bivalent hybrid of s. typhimurium vaccine strain 274 and s. dublin induced only pronounced blast transformation in lymph ... | 1992 | 1481606 |
| predicting the growth of salmonella typhimurium on beef by using the temperature function integration technique. | lag and generation times for the growth of salmonella typhimurium on sterile lean beef were modeled as functions of cooling time under various carcass-chilling scenarios. gompertz growth models were fit to the log10 colony counts over time at each of six temperatures in the range of 15 to 40 degrees c. lag and generation times were defined as the points at which the second and first derivatives, respectively, of each growth curve attained a maximum. generation time and lag time parameters were m ... | 1992 | 1482173 |
| characterization of the micro-environment of salmonella typhimurium-containing vacuoles within mdck epithelial cells. | salmonella typhimurium has the capacity to enter into and multiply within epithelial cells. during the entire intracellular stage, bacteria are enclosed within a vacuole. to characterize the micro-environment of the bacteria-containing vacuoles, we have used a new method to measure the expression levels of several s. typhimurium genes in intracellular bacteria within madin-darby canine kidney (mdck) epithelial cells. our study was based on the determination of beta-galactosidase activity derived ... | 1992 | 1484485 |
| proposed nomenclature for the genes involved in molybdenum metabolism in escherichia coli and salmonella typhimurium. | | 1992 | 1484496 |
| effects of metallothionein on mutagenicity and oxidation of quercetin. | the effects of four types of zn/cd-metallothioneins on the mutagenicity of quercetin in salmonella typhimurium ta98 were studied. the four types of zn/cd-metallothionein used in this experiment were metallothionein i, metallothionein i/ii and metallothionein ii from rabbit liver and metallothionein i/ii from horse kidney. all four of the metallothioneins enhanced the mutagenicity of quercetin. metallothionein ii from rabbit liver, in which zn content was the highest of the four metallothioneins, ... | 1992 | 1488255 |
| further characterization of the histidine gene cluster of streptomyces coelicolor a3(2): nucleotide sequence and transcriptional analysis of hisd. | we have further characterized the genomic region of streptomyces coelicolor a3(2) that contains genes involved in the biosynthesis of histidine. a 2,357-base pair fragment contained in plasmid psch3328 that complemented hisd mutations has been sequenced. computer analysis revealed an open reading frame that encodes a protein with significant homology to the escherichia coli, salmonella typhimurium and mycobacterium smegmatis hisd product, saccharomyces cerevisiae his4c, and neurospora crassa his ... | 1992 | 1488552 |
| the origin of his+ revertants of salmonella typhimurium obtained on selective medium. | the spontaneous reversion to his+ of the salmonella typhimurium alleles hisd3052 and hisg46 was investigated. in fluctuation tests, the expected "jackpot" distribution of his+ revertants was not observed. the experimental distributions were close to poisson distribution. the redistribution test showed no significant differences in the his+ colony counts between spread and unspread plates. an attempt at indirect selection of his+ revertants in fluid medium failed. it was also shown that the mean ... | 1992 | 1488555 |
| incubation period, severity of disease, and infecting dose: evidence from a salmonella outbreak. | the associations between infecting dose, incubation period, and the severity of disease were examined in a large outbreak of salmonella typhimurium which occurred at a medical conference in wales in 1986. persons who had eaten two or more pieces of the chicken vehicle had, on average, shorter geometric mean incubation periods than those who had only eaten one piece: 16.6 hours (95% confidence interval (ci) 13.5-20.5) compared with 20.7 hours (95% ci 19.0-22.6) (t = 1.97, p < 0.05). incubation pe ... | 1992 | 1488963 |
| fluoranthene metabolism: human and rat liver microsomes display different stereoselective formation of the trans-2,3-dihydrodiol. | the metabolism of the environmental carcinogen fluoroanthene by human liver microsomes was compared to that by liver microsomes from rats treated with aroclor 1254. although the human-derived system gave primarily one product, similar metabolites were noted from each system. enantiomers of the major metabolic product, in both cases the trans-2,3-dihydrodiol, were separated by chiral stationary-phase chromatography. absolute configurations were assigned by application of the benzoate exciton chir ... | 1992 | 1489928 |
| characterization of (+/-)-7,8,10-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene-9-sulfonate. | the genotoxicity of certain benzo[a]pyrene (bp) derivatives is significantly enhanced in strains of salmonella typhimurium following addition of sulfite to the incubations. the interaction between sulfite and those bp derivatives also results in the formation of isomeric bp sulfonates. as these trihydroxy sulfonates are formed in incubations of bp derivatives and sulfite in which a marked potentiation of bacterial mutagenicity occurs, we have investigated the properties of these novel intermedia ... | 1992 | 1489935 |
| the putative sigma factor katf (rpos) is required for the transcription of the salmonella typhimurium virulence gene spvb in escherichia coli. | the virulence of salmonella typhimurium for mice is dependent on a plasmid-borne gene cluster termed spv. we previously determined that both s. typhimurium and escherichia coli bacteria grown in a rich medium preferentially express the spv genes during the stationary phase of growth. in this study we evaluated the role of katf, a putative sigma factor for starvation- and stationary phase-induced genes, in the expression of the spvb gene. the transcription of spvb in e. coli was compared in katf ... | 1992 | 1490610 |
| [genotoxic activity test of sodium fluoride in vitro]. | the artificial drinking water fluoridization provided as a mass preventive measure against dental decay poses another substantial problem which is a possibility of genotoxic action. up to this date, this matter remains still obscur and is discussed with more or less intensity from time to time. the mentioned fact supported authors to study the impact of short-term 24 hrs sodium fluoride (naf) action in concentration range of 0-500 mg.1(-1) drinking water in the frame of so-called minimal testing ... | 1992 | 1492198 |
| the role of gm-csf in infection. | gm-csf is a hemopoietic growth factor with substantial effects on the proliferation of neutrophils, eosinophils and monocytes/macrophages. its physiologic role in infection is still poorly understood. the gene for gm-csf is constitutively transcribed in cells substantial for antiinfectious response. various cells are activated and induced by tnf and il-1 to synthesize gm-csf. no systemic gm-csf levels can be detected in patients with infection. it is likely that gm-csf plays its physiological ro ... | 1992 | 1493940 |
| the role of protein and calorie restriction in outcome from salmonella infection in mice. | we studied the separate effects of protein and calorie restriction in mice challenged with salmonella typhimurium, an intracellular pathogen eliminated by cell-mediated immunity. female a/j mice (n = 73) were placed on one of eight solid diets for 3 weeks. animals were weighed at the beginning and the end of the feeding period. diets were adjusted by two factors. the total amount of protein in the diet was 1%, 5%, 20%, or 40% by weight. the diets were fed to half the mice in quantities of 3 g an ... | 1992 | 1494214 |
| [bacteremia caused by non-typhoid salmonellas during an infection by the human immunodeficiency virus (hiv) in the african adult]. | infection caused by non-typhous salmonellae during the course of hiv infection is known since 1983. the authors report on 103 bacteremiae of this type found in one year. diagnosis has been based on hemocultures. 86 patients out of 103 were hiv+. all of them were febrile. 67 suffered from digestive disorders, 33 with diarrhoea. splenomegalia was noted in 16 cases and consciousness troubles in 13 cases. at the admission, 8 complications were observed. other infections were associated in 86 cases p ... | 1992 | 1494316 |
| nucleotide sequence analysis and comparison of the lexa genes from salmonella typhimurium, erwinia carotovora, pseudomonas aeruginosa and pseudomonas putida. | the complete nucleotide sequences of the lexa genes from salmonella typhimurium, erwinia carotovora, pseudomonas aeruginosa and pseudomonas putida were determined; the dna sequences of the lexa genes from these bacteria were 86%, 76%, 61% and 59% similar, respectively, to the escherichia coli k12 gene. the predicted amino acid sequences of the s. typhimurium, e. carotovora and p. putida lexa proteins are 202 residues long whereas that of p. aeruginosa is 204. two putative lexa repressor binding ... | 1992 | 1494343 |
| a salmonella dublin virulence plasmid locus that affects bacterial growth under nutrient-limited conditions. | this paper reports the characterization of a new locus, vagc/vagd, on the virulence plasmid of salmonella dublin. strain g19, harbouring a tna insertion in vagc, exhibited reduced virulence although vagc was outside the 8 kb essential virulence region. g19 was also unable to grow on minimal-medium containing various sole carbon/energy sources, unlike the wild-type and plasmid-cured strains. sequencing of the locus revealed the presence of two orfs (vagc and vagd) which overlapped by one nucleoti ... | 1992 | 1495391 |
| cloning and sequencing of the melb gene encoding the melibiose permease of salmonella typhimurium lt2. | the nucleotide sequence of the melb gene coding for the na+ (li+)/melibiose symporter of salmonella typhimurium lt2 was determined, and its amino acid sequence was deduced. it consists of 1428 bp, corresponding to a protein of 476 amino acid residues (calculated molecular weight 52,800). the amino acid sequence is homologous to that of the melibiose permease of escherichia coli k12, with 85% identical residues. all, except one, of the amino acid residues that have been reported to be important f ... | 1992 | 1495487 |
| calf exports and salmonella typhimurium incidents in uk calves. | | 1992 | 1496777 |
| [the morphological assessment of the safety and protective activity of the vaccinal strain salmonella typhimurium 274]. | | 1992 | 1496875 |
| bioactivation of aflatoxin b1 in the bovine olfactory mucosa: dna binding, mutagenicity and induction of sister chromatid exchanges. | nasal olfactory tumours occur in cattle in relatively high frequencies in several developing countries. since affected animals sometimes show signs of severe aflatoxicosis, a role of aflatoxin b1 (afb1) in tumorigenesis can be proposed. the results of the present study show that microsomal preparations of the bovine olfactory mucosa have a much higher ability than liver microsomes to induce covalent binding of afb1 to calf thymus dna and to microsomal proteins. the major dna adduct formed was 8, ... | 1992 | 1499086 |
| the evaluation in the ames test of the mutagenicity of tetrahydro-beta-carboline-3-carboxylic acids from smoked foods. | this paper reports the evaluation of five tetrahydro-beta-carboline carboxylic acids, formed from the interaction of woodsmoke carbonyls and tryptophan, for mutagenicity in the ames test. three of the compounds tested have been detected recently in smoked foods at levels in the micrograms/kg or mg/kg range. none of the compounds induced mutagenicity in ta 97, ta 98 or ta 100 strains of salmonella typhimurium either with or without prior activation. however, tetrahydro-beta-carboline-3-carboxylic ... | 1992 | 1499775 |
| elimination of the vitamin b12 uptake or synthesis pathway does not diminish the virulence of escherichia coli k1 or salmonella typhimurium in three model systems. | the role of iron in infection is of great importance and is well understood. during infection, both the host and the pathogen go through many complicated changes to regulate iron levels. iron and vitamin b12 share certain features. for example, escherichia coli has similar transport systems for both nutrients, and binding proteins for both are located in gastric juice, liver, saliva, granulocytes, and milk. it is because of such parallels between iron and b12 that we have explored the role of b1 ... | 1992 | 1500158 |
| cryptdins: antimicrobial defensins of the murine small intestine. | paneth cells are specialized small intestine epithelial cells that contain lysozyme, possess phagocytic properties, and secrete cytoplasmic granules into the intestinal crypt lumen after the entry of bacteria. recent studies by ouellette and associates (a. j. ouellette, r. m. greco, m. james, d. frederick, j. naftilan, and j. t. fallon, j. cell biol. 108:1687-1695, 1989) indicated that murine paneth cells produce prodefensin mrna, but the properties of its peptide product were not reported. we p ... | 1992 | 1500163 |