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keeping the immune system alerted against cancer. 19989558004
interactions of listeria monocytogenes with infected host cells. video supplement. 19989556334
genetic typing of human and food isolates of listeria monocytogenes from episodes of listeriosis.ten clinical and food listeria monocytogenes strains isolated during the epidemiological investigations of episodes of listeriosis (one outbreak and two sporadic cases) that occurred in northern italy during 1993-1995 have been examined by dna macrorestriction pattern analysis obtained by pfge and rapd typing, in order to confirm the food vehicle of infections. the same dna profiles within the isolates from the three episodes were obtained by both techniques. the apal and smal pfge profiles and ...19989556182
characterization of plasmids from listeria monocytogenes and listeria innocua strains isolated from short-ripened cheeses.the plasmid content of 30 isolates of listeria monocytogenes and 18 isolates of listeria innocua obtained from short-ripened cheeses was analysed. the isolates of l. monocytogenes serogroup 1 harboured a single plasmid, plm33 (33.2 kbp), whereas the serogroup 4 isolates did not contain plasmids. one group of l. innocua strains harboured the plasmid pli71 (71 kbp) and another one contained two plasmids: pli59 (59.5 kbp) and pli56 (56.5 kbp). these plasmid groups were in accordance with clusters p ...19989553802
interaction of monolaurin, eugenol and sodium citrate on growth of common meat spoilage and pathogenic organisms.interactions of monolaurin, eugenol (phenolic compound) and sodium citrate (chelator) on the growth of six organisms including common meat spoilage (lactobacillus curvatus, lactobacillus sake, leuconostoc mesenteroides, brochothrix thermosphacta) and pathogenic (escherichia coli o157:h7 and listeria monocytogenes) organisms were investigated. the combinations of 100 to 250 ppm monolaurin with 500 and 1000 ppm eugenol, and 0.2 and 0.4% sodium citrate were more effective than each component separa ...19989553796
predictive modelling of inactivation of listeria spp. in bovine milk during high-temperature short-time pasteurization.a linear model was derived to describe the thermal inactivation of listeria innocua in bovine whole milk in a high-temperature short-time pilot scale pasteurizer. integrated lethal effect, or pasteurization effect (pe), was obtained by converting times at different temperatures in the various sections of the pasteurizer to the equivalent time at the reference temperature (72 degrees c). pe was then related by a simple linear function to the log10 of the % viable counts with a power transformatio ...19989553795
inhibition of listeria monocytogenes and salmonella enteriditis by combinations of plant oils and derivatives of benzoic acid: the development of synergistic antimicrobial combinations.this study describes inhibitory properties of combinations of oil of fennel, oil of anise or oil of basil with either benzoic acid or methyl-paraben against listeria monocytogenes and salmonella enteriditis. micro-organisms were cultured at 37 degrees c in broth and viable counts measured over a 48-h period. s. enteriditis was particularly sensitive to inhibition by a combination of oil of anise, fennel or basil with methyl-paraben where there was < 10 cfu/ml after 1 h. l. monocytogenes was less ...19979552716
chronic listeria infection in scid mice: requirements for the carrier state and the dual role of t cells in transferring protection or suppression.listeriosis in mice with the scid mutation results in a chronic infection. the chronic infection is characterized by abundant granulomas and neutrophil infiltrates. both lesions were particularly noticeable in the liver. in the liver, about 95% are granulomas with 5% microabscesses involving intrahepatic infection. the majority of listeria resided in membrane-bound vacuolar structures of the macrophages and not in the cytosol. three manipulations resulted in alterations in the equilibrium betwee ...19989551994
perforin-deficient cd8+ t cells provide immunity to listeria monocytogenes by a mechanism that is independent of cd95 and ifn-gamma but requires tnf-alpha.cd8+ t cells are effective mediators of immunity against listeria monocytogenes, but the mechanisms by which they provide antilisterial immunity are poorly understood. cd8+ t cells efficiently lyse target cells in vitro by at least two independent pathways. to test the hypothesis that cd8+ t cell-mediated immunity to l. monocytogenes is dependent on perforin or cd95 (fas, apo-1), we used c57bi/6 (b6) and perforin-deficient (po) mice to generate cd8+ t cell lines specific for the l. mono cytogene ...19989551927
evidence that the same gamma delta t cells respond during infection-induced and autoimmune inflammation.inflammatory responses are induced in both testes of a mouse following injection of listeria monocytogenes into one testis. although the uninjected testis contains no detectable bacteria, it undergoes an autoimmune attack. normally, the testis lacks lymphocytes, but in the infected and autoimmune state, both gamma delta and alpha beta t cells are found as infiltrates. here, we have examined the repertoire of the infiltrating gamma delta t cells, using two different methods, and found a high freq ...19979550374
the effects of inoculation of listeria monocytogenes into the ovine mammary gland.in each of two experiments, the effects of inoculation of listeria monocytogenes into the ovine mammary gland were studied. in the first experiment, ewes were challenged with one or other of five different listeria spp. isolates to study differences in their pathogenicity. in the second, ewes were challenged with l. monocytogenes serotype 1/2a to study the sequential features of the infection. the reaction of the mammary glands was assessed by bacteriological, cytological and histological method ...19989549859
neuropeptides in the livers of mice during bacterial infections.neuropeptides such as substance p (sp) and vasoactive intestinal peptide (vip) are known to act as immunomodulators. we investigated the induction of sp and vip in the livers of mice infected with listeria monocytogenes or injected with tsukamurella paurometabolum. vip was detected in the livers of mice after l. monocytogenes infection by an immunohistochemical technique and preprovip mrna, which was detected by reverse transcription-polymerase chain reaction (pcr), was induced post infection. h ...19989544784
attachment of group b streptococci to macrophages is mediated by a 21-kda protein.group b streptococcus (gbs) is able to bind to human macrophages in vitro in the absence of exogenous opsonins. the exact mechanisms that mediate this attachment are unclear. this study was undertaken to determine what protein adhesins are present on the surface of gbs that mediate attachment to macrophages. we have identified a 21-kda protein from the envelope of gbs type iii that directly binds to macrophages as determined by western blot analysis. antiserum against this protein was able to in ...19989544775
comparison of pcr-based dna fingerprinting techniques for the identification of listeria species and their use for atypical listeria isolates.four pcr-based dna fingerprinting techniques were compared for their ability to identify at the species level a heterogeneous collection of isolates belonging to the six valid listeria species. 16s rdna-rflp analysis identified all species and 16s rdna-sscp analysis identified almost all species. also, isolates with unusual biochemical characteristics and/or unusual antigenic composition could be identified correctly. rrna-intracistronic length polymorphism analysis suffered from high intraspeci ...19989542083
[listeria monocytogenes-induced endogenous endophthalmitis in an otherwise healthy patient: pcr-assisted rapid diagnosis as the basis for successful therapy].listeria monocytogenes is a rare cause of endogenous endophthalmitis. only 14 cases are published in the literature so far. all eyes showed similar clinical features and profound visual loss.19989541896
identification and characterization of nucleotide sequence differences in three virulence-associated genes of listeria monocytogenes strains representing clinically important serotypes.listeria monocytogenes is a gram-positive, facultative intracellular bacterium that causes invasive, often fatal, disease in susceptible hosts. as a foodborne pathogen, the bacterium has emerged as a significant public health problem and has caused several epidemics in the united states and europe. three serotypes (1/2a, 1/2b, 4b) of l. monocytogenes are responsible for nearly 95% of all reported cases of human listeriosis. l. monocytogenes serotype 4b has caused all well-characterized foodborne ...19989541569
flow cytometry demonstrates bacteriocin-induced injury to listeria monocytogenes.flow cytometry was used to study the effect of the bacteriocin leucocin b-ta11a on listeria (l.) monocytogenes. mixed proportions of dead and live control populations were analyzed by flow cytometry to determine detection limits of the dead/live baclight bacterial viability kittm. high correlations for flow cytometric detection of defined proportions of live or dead cells in mixtures between 10 and 100% of dead (r2 = 0.97) or live (r2 = 0.99) cells were obtained. however, mixtures containing les ...19989541561
[pustular dermatitis in veterinarians following delivery in farm animals; an occupational disease].to assess the prevalence of contact dermatitis after deliveries in cattle or sheep among veterinarians.19989537088
effect of granulocyte-macrophage colony-stimulating factor on the number of leucocytes and course of listeria monocytogenes infection in naive and leucocytopenic mice.this study concerns the effect of recombinant murine granulocyte-macrophage colony-stimulating factor (gm-csf) on the number of circulating leucocytes, activation of peritoneal macrophages and proliferation of listeria monocytogenes in various organs of naive and leucocytopenic mice. mice were rendered leucocytopenic by sublethal total body irradiation or cyclophosphamide treatment. gm-csf treatment enhanced the number of granulocytes and monocytes in peripheral blood during l. monocytogenes inf ...19989536121
the inib protein of listeria monocytogenes is sufficient to promote entry into mammalian cells.inib is one of the two listeria monocytogenes invasion proteins required for bacterial entry into mammalian cells. entry into human epithelial cells such as caco-2 requires inia, whereas inib is needed for entry into cultured hepatocytes and some epithelial or fibroblast cell lines such as vero, hep-2 and hela cells. inib-mediated entry requires tyrosine phosphorylation, cytoskeletal rearrangements and activation of the host protein phosphoinositide (pi) 3-kinase, probably in response to engagem ...19989535096
differential interaction of the transcription factor prfa and the prfa-activating factor (paf) of listeria monocytogenes with target sequences.the interaction of the purified prfa transcription factor with the regulatory sequences located upstream of the prfa-dependent listeriolysin (hly) and internalin (inla) genes was studied in the presence and in the absence of paf (prfa-activating factor)-containing extracts. it is shown that prfa protein is able to bind, independently of additional factors, to a 109bp dna fragment including the entire hly promoter sequence with the anticipated prfa binding site ('prfa-box'). prfa alone, but not i ...19989535082
determination of a 15437 bp nucleotide sequence around the inha gene of mycobacterium avium and similarity analysis of the products of putative orfs.a 15437 bp region encompassing the inha locus from the mycobacterium avium chromosome was cloned and sequenced. from the sequencing data generated and the results of homology searches, the primary structure of this region was determined. this region contains four known genes (acna, fabg, inha and hemh) and two genes, inva and invb, whose products display homology with p60 invasion protein of listeria monocytogenes. six proteins encoded by putative orfs contained an rgd motif (often involved in b ...19989534249
the regulatory role of heat shock protein 70-reactive cd4+ t cells during rat listeriosis.protection against infection with listeria monocytogenes depends primarily on listeria-specific t cells. we show here that cd4+ tcr alphabeta+ t cells are capable of recognizing the mycobacterial heat shock protein (hsp) 70, that appears in the peritoneal cavity of f344 rats infected i.p. with l. monocytogenes. the hsp70-reactive cd4+ t cells recognized a peptide comprising 234-252 residues as present in the 70 kda hsp of mycobacterium tuberculosis in the context of rt1.b mhc class ii molecules. ...19989533439
listeriosis.listeria monocytogenes is ubiquitous in nature and is part of the normal flora of the distal portion of the intestinal tract of numerous animal species. listeriosis is an emerging food borne disease that is responsible for approximately 1,700 cases of human illness each year and 650 deaths. listeria is the cause of three main disease entities in animals and humans: neural, visceral, and reproductive. clinical signs associated with the three forms are discussed along with diagnosis, therapy, prev ...19989532671
multiple hemopoietic defects and lymphoid hyperplasia in mice lacking the transcriptional activation domain of the c-rel protein.the c-rel protooncogene encodes a member of the rel/nuclear factor (nf)-kappab family of transcriptional factors. to assess the role of the transcriptional activation domain of c-rel in vivo, we generated mice expressing a truncated c-rel (deltac-rel) that lacks the cooh-terminal region, but retains a functional rel homology domain. mice with an homozygous mutation in the c-rel region encoding the cooh terminus of c-rel (c-reldeltact/deltact) display marked defects in proliferative and immune fu ...19989529314
coordinate regulation of complex t cell populations responding to bacterial infection.bacterial infections activate complex t cell populations that differ in size and antigen specificity. we used tetramerized mhc class i molecules complexed with listeria monocytogenes-derived epitopes to characterize four distinct cd8+ t lymphocyte populations during bacterial infection. surprisingly, t cell populations differing in antigen specificity expand, contract, and enter the t cell memory compartment synchronously. because the four l. monocytogenes epitopes are presented with different e ...19989529152
psychrotrophic bacteria isolated from a constantly warm tropical environment.psychrotrophic bacteria are known to occur in temperate, constantly cold, and artificially cooled environments. this is the first report of their occurrence in a constantly warm (ca. 24 degrees-35 degrees c) tropical environment. soil samples taken from two sites along the southeastern coastal zone of jamaica yielded growth of psychotrophic bacteria after 3-4 weeks of enrichment culture in 1/30 strength tryptic soy broth, 20 mg l-1 cycloheximide at 2 degrees c. growth of individual isolates at 2 ...19989516542
a broad-host-range mobilizable shuttle vector for the construction of transcriptional fusions to beta-galactosidase in gram-positive bacteria.a low-copy-number vector designated ptcv-lac has been constructed to provide a convenient system to analyze regulatory elements in gram-positive bacteria. the main components of this vector are: (i) the origins of replication of pacyc184 and of the broad-host-range enterococcal plasmid pam beta 1, (ii) erythromycin- and kanamycin-resistance-encoding genes for selection in gram-negative and gram-positive bacteria, (iii) the transfer origin of the incp plasmid rk2, and (iv) a promoterless beta-gal ...19979513264
dna fingerprinting of listeria monocytogenes using enterobacterial repetitive intergenic consensus (eric) motifs-polymerase chain reaction/capillary electrophoresis.the molecular technique, enterobacterial repetitive intergenic consensus (eric)-polymerase chain reaction (pcr) produces genomic dna fingerprint that discriminate bacterial species and strains. this technique was applied to the characterization of listeria monocytogenes, an important food-borne pathogen implicated in numerous cases of listeriosis. the eric-pcr resulted in distinct dna fingerprinting patterns of all l. monocytogene serotypes and listeria species. analysis of the genomic dna finge ...19989511864
killing mechanism of listeria monocytogenes in activated macrophages as determined by an improved assay system.exposure of listeria monocytogenes to gentamicin 5 mg/l for 4 h resulted in the killing of most extracellular bacteria, but had no effect on the survival of bacteria inside macrophages. higher concentrations of gentamicin caused a reduction in the number of intracellular bacteria. this effect was associated with cellular uptake of gentamicin, but was unaffected by activation of macrophages by interferon-gamma and lipopolysaccharide. in experiments in which exposure to gentamicin 5 mg/l for 4 h w ...19989511826
cell proliferation enhances entry of listeria monocytogenes into intestinal epithelial cells by two proliferation-dependent entry pathways.bacterial entry into intestinal host cells is the result of a fairly sophisticated manipulation of host cell machinery by the pathogens. to study further the potential cell target of listeria spp., the in-vitro entry of l. monocytogenes strains into intestinal cells was examined in relation to the metabolism, proliferation and differentiation of the cells by the alamarblue assay, [3h] thymidine incorporation, and brush border-associated enzyme activities, respectively. the study showed that cell ...19979511817
minimal inhibitory concentrations and minimal bactericidal concentrations of quinupristin/dalfopristin against clinical isolates of corynebacterium jeikeium and listeria monocytogenes.thirty clinical isolates of listeria monocytogenes and 30 clinical isolates of corynebacterium jeikeium were tested against quinupristin/dalfopristin by the nccls broth macrodilution technique for determination of mics. mbc testing was also performed on the 60 isolates. quinupristin/dalfopristin mic90 values against l. monocytogenes and c. jeikeium were 1.6 mg/l and 0.2 mg/l, respectively. quinupristin/dalfopristin was bacteriostatic against these organisms.19979511066
effects of avgard treatment on the microbiological flora of poultry carcases.1. the efficiency of the avgard (or assur-rince in the usa) trisodium phosphate poultry carcase decontamination process was evaluated during both manual and industrial trials against total aerobic mesophilic count (tamc), thermotolerant coliforms, pseudomonas, enterobacteriaceae, campylobacter, listeria monocytogenes and salmonella. 2. the tsp treatment proved to have significant effects on the bacterial decontamination of poultry neck skin, lowering the contamination by a factor of about 10 for ...19979510992
immunity to listeria monocytogenes. 19989509668
antimicrobial activity of extracts of mutisia acuminata var. acuminata.the biological activity of methanol and water extracts of mutisia acuminata ruiz et pavon var. acuminata (asteraceae) against bacteria and fungi (spores and mycelia) was evaluated. the role of ph of the medium in antimicrobial activity was investigated.19989507906
inhibition of listeria monocytogenes on cold-smoked salmon by nisin and carbon dioxide atmosphere.the bacteriostatic and bacteriocidal effect of nisin in combination with carbon dioxide, nacl and low temperature on the survival of listeria monocytogenes was investigated in in vitro model studies and in trials with cold-smoked salmon. addition of nisin caused various degrees of inhibition and sometimes death of l. monocytogenes in model experiments performed at 10 degrees c. the antilisterial effect of nisin was improved in the presence of 100% co2 and increasing nacl concentrations (0.5 to 5 ...19979506287
a model describing the relationship between lag time and mild temperature increase duration.when a bacterial population undergoes an unfavourable increase in temperature for a given duration, called stress duration, a death phase followed by a lag and a growth phase are observed. the lag phase is actually of great interest in regard to foodstuff safety in choosing a suitable protocol for the detection of microorganisms which have undergone a mild heat treatment. the extension of lag time with the severity of the increase in temperature has been highlighted by previous papers. our exper ...19979506281
peritonitis due to listeria monocytogenes in a patient receiving maintenance hemodialysis. 19989502491
utilization of oligopeptides by listeria monocytogenes scott a.for effective utilization of peptides, listeria monocytogenes possesses two different peptide transport systems. the first one is the previously described proton motive force (pmf)-driven di- and tripeptide transport system (a. verheul, a. hagting, m.-r. amezaga, i. r. booth, f. m. rombouts, and t. abee, appl. environ. microbiol, 61:226-233, 1995). the present results reveal that l. monocytogenes possesses an oligopeptide transport system, presumably requiring atp rather than the pmf as the driv ...19989501445
public health and pork and pork products: regional perspectives of denmark.an ambitious programme to eliminate pork as an important source of human salmonellosis was initiated in denmark in 1993 by the ministry of food, agriculture and fisheries. the programme comprises control of feedmills, breeding and multiplying herds, slaughter herds and slaughter plants, as well as the final product, fresh pork. as a consequence, the level of occurrence of salmonella spp. in fresh pork produced in denmark is approximately 1%. yersinia enterocolitica 0:3 infections are common in s ...19979501365
risks and prevention of contamination of dairy products.consumers and regulatory officials are becoming increasingly aware of the human health risk of the presence of micro-organisms or chemicals in the agricultural environment. providing 'on-farm food safety' programmes which address the daily management of the production unit with regard to animal health and well-being, public health and environmental health must be a top priority for agriculturalists and veterinarians. developing critical control point management (ccpm) procedures for animal and h ...19979501360
[pathogenic organisms in milk and milk products: the situation in france and in europe].milk and dairy products harbour a natural microbial flora and/or other micro-organisms, which vary within the wide range of products available on the french market. the origin of contamination by pathogenic bacteria varies with the type of product and the mode of production and processing. contamination of milk and dairy products by pathogenic micro-organisms can be of endogenous origin, following excretion from the udder of an infected animal. contamination may also be of exogenous origin, thro ...19979501359
milk pasteurisation and safety: a brief history and update.a brief history of the development of milk pasteurisation is presented and updated. concerns about the margin of safety provided by current pasteurisation standards in terms of milk-borne pathogens such as mycobacteria (in particular mycobacterium paratuberculosis) and other emerging pathogens such as listeria monocytogenes and escherichia coli o157:h7 are discussed. with the exception of the endospores of bacillus cereus, current standards appear to be adequate for public health assurance of mi ...19979501358
meat from dairy cows: possible microbiological hazards and risks.the authors provide an overview of the circumstances associated with culling of dairy cattle in the united states of america (usa) and focus on the possible significant microbiological hazards associated with meat from cull dairy cows. cull dairy cows are an important source of food in the usa, accounting for at least approximately 17% of ground beef. the potential microbiological hazards for foodborne illness from cull dairy cows discussed here include salmonella (with special attention to s. t ...19979501354
intensive (pasture) beef cattle operations: the perspective of new zealand.beef production in new zealand has characteristics typical of a temperate climate and pasture-based animal husbandry. the specific pathogens which may contaminate fresh beef and which are empirically considered to be of public health importance are similar to those in other countries with temperate climates, i.e. salmonella, campylobacter, escherichia coli o157:h7, listeria monocytogenes and toxoplasma gondii. with the exception of t. gondii, it is likely that almost all transmission of these ha ...19979501351
single-strand conformation polymorphism (sscp) analysis of listeria monocytogenes iap gene as tool to detect different serogroups.pcr-single-strand conformation polymorphism (pcr-sscp) analysis is a convenient technique for the detection of mutations. as the mobility of single-stranded dna is sequence-dependent it could therefore be used to determine serotype-related sequence variations in listeria monocytogenes. sero-specific patterns were observed in different l. monocytogenes serogroups.19979500812
a pcr-microplate capture hybridization method to detect listeria monocytogenes in blood.in order to improve the diagnosis of listeria monocytogenes infection, we have developed a polymerase chain reaction (pcr)-based assay combined with microplate capture hybridization technique. the system is based on selective amplification of l. monocytogenes with two specific primers based on the iap gene. the amplicon produced, with digoxigenin 11-dutp incorporated during pcr, is hybridized in streptavidin-coated microtitre plates prepared with biotinylated specific dna probe. the method invol ...19979500808
addition of 2.5% lactate and 0.25% acetate controls growth of listeria monocytogenes in vacuum-packed, sensory-acceptable servelat sausage and cooked ham stored at 4 degrees c.a study of the inhibitory effects of propylparaben and of a combination of lactate and acetate against growth of listeria monocytogenes in inoculated liquid medium, sliced servelat sausage and cooked ham, were performed using rifampicin resistant listeria strains in inoculation experiments. a consumer acceptance test of products produced with and without the compounds was also performed. propylparaben was found to be effective in a model liquid non-fat medium, but was without effect in the actua ...19979498139
classification of listeria monocytogenes by pcr-restriction enzyme analysis in the two genes of hlya and iap.pcr-restriction enzyme analysis in the two virulence-associated genes was performed. the hlya gene cording for listeriolysin o and the iap gene cording for an invasion associated factor were amplified with primers sh2 or si3. the pcr products obtained were cleaved with 32 restriction enzymes, and restriction profiles from 12 strains, 6 each of serotypes 1/2a and 4b, were compared. we obtained two profiles for the hlya using 4 restriction enzymes and eight profiles for the iap by using alui, and ...19989497934
in situ detection of a virulence factor mrna and 16s rrna in listeria monocytogenes.simultaneous in situ analysis of the structure and function of bacterial cells present within complex communities is a key for improving our understanding of microbial ecology. a protocol for the in situ identification of listeria spp. using fluorescently tagged, rrna-targeted oligonucleotide probes was developed. ethanol fixation and enzymatic pretreatment with lysozyme and proteinase k were used to optimize whole cell hybridization of exponential phase and stationary phase listeria spp. cells. ...19989495027
the microtubule depolymerizing drugs nocodazole and colchicine inhibit the uptake of listeria monocytogenes by p388d1 macrophages.uptake of listeria monocytogenes by different mammalian cells like macrophages and epithelial cells is dependent on functional actin filaments and hence susceptible to inhibition by cytochalasin. here we show that phagocytic uptake of l. monocytogenes by p388d1 macrophages is also highly sensitive to treatment with the microtubule depolymerizing drugs nocodazole and colchicine. this sensitivity is cell type specific and much less pronounced in bone marrow-derived macrophages and caco-2 epithelia ...19989495017
compartmentalization of bacterial antigens: differential effects on priming of cd8 t cells and protective immunity.bacterial pathogens synthesize numerous proteins that are either secreted or localized within bacterial cells. to address the impact of antigen compartmentalization on t cell immunity, we constructed recombinant listeria monocytogenes that express a model cd8t cell epitope as a secreted or nonsecreted fusion protein. both forms of the antigen, either secreted into the host cell cytoplasm or retained within bacterial cells, efficiently prime cd8 t cell responses. however, epitope-specific cd8 t c ...19989491894
sequence comparison of the chromosomal regions encompassing the internalin c genes (inlc) of listeria monocytogenes and l. ivanovii.we have recently cloned and characterized the inlc gene of listeria monocytogenes which belongs to the listerial internalin multigene family and codes for a 30-kda secreted protein containing five consecutive leucine-rich repeats. here, we show that in l. monocytogenes inlc is located between the rpls gene (encoding the 50s ribosomal protein l19), and the infc gene (encoding the translation initiation factor 3). by direct and inverse polymerase chain reactions (pcr), we cloned a 5.4-kb region co ...19989491077
separation of listeria monocytogenes and salmonella berta from a complex food matrix by aqueous polymer two-phase partitioning.in the present study, the use of aqueous polymer two-phase systems for separation of pathogenic bacteria from a complex food sample was investigated. three different two-phase systems, a polyethylene glycol 3350/dextran t 500, a methoxy polyethylene glycol 5000/dextran t 500 and a polyethylene glycol 3350/hydroxypropyl starch system, were compared at ph 3 and ph 6 for their capacity to separate the pathogenic bacteria listeria monocytogenes and salmonella berta from a cumberland sausage. in all ...19989489033
fitness costs associated with class iia bacteriocin resistance in listeria monocytogenes b73.in order to assess the potential for the spread of class iia bacteriocin resistance in natural populations of listeria monocytogenes, the fitness costs associated with resistance to leucocins a, b and e and sakacin a in l. monocytogenes b73 in the absence of bacteriocin were examined. the resistant phenotype had a lower growth rate (and thus relative fitness) than the sensitive phenotype in monoculture experiments. furthermore, resistant phenotypes were unable to invade populations of the sensit ...19989489026
listeria monocytogenes invasion of epithelial cells requires the mek-1/erk-2 mitogen-activated protein kinase pathway.pd98059, a specific inhibitor of mek-1 mitogen-activated protein (map) kinase kinase, blocked listeria monocytogenes invasion into hela epithelial cells. the effects of pd98059 were reversible, as adherent extracellular bacteria were internalized upon removal of the drug. previously, we reported that l. monocytogenes could activate erk-1 and erk-2 map kinases through the action of listeriolysin o (llo) on the host cell (p. tang, i. rosenshine, p. cossart, and b. b. finlay, infect. immun. 64:2359 ...19989488402
h2m3wt-restricted, listeria monocytogenes-immune cd8 t cells respond to multiple formylated peptides and to a variety of gram-positive and gram-negative bacteria.a subset of h2m3wt-restricted, listeria monocytogenes (lm)-immune cd8 effectors recognize antigen-presenting cells (apc) preincubated with heat-killed lm. the responsible product, which we have previously designated heat-killed listeria-associated antigen (haa), is extremely hydrophobic and resistant to proteolytic degradation. despite the protease resistance of haa, we now report that haa-immune clones are uniformly responsive to fmigwii, a formylated oligopeptide derived from the recently desc ...19989488151
delivery of antigen-encoding plasmid dna into the cytosol of macrophages by attenuated suicide listeria monocytogenes.eukaryotic expression vectors can be delivered to macrophages using attenuated self-destructing listeria monocytogenes. l. monocytogenes cells are preferentially lysed in the host cell macrophage cytosol by the production of a pacta-dependent listeria-specific phage lysin. efficient expression of the cloned reporter genes by the macrophages and subsequent antigen presentation were achieved after the delivery of eukaryotic expression vectors by the attenuated suicide l. monocytogenes strain. afte ...19989487527
bacterial delivery of dna evolves. 19989487514
control of actin dynamics.actin-based motility processes are tightly linked to the rapid turnover of actin filaments. factors that control the steady state of actin assembly, such as capping proteins and actin-depolymerizing factor/cofilin, directly affect motility. actin-depolymerizing factor increases the treadmilling of actin filaments in vitro and in vivo. cellular factors that are involved in linking initiation of barbed end assembly to cell signaling are being identified using listeria monocytogenes and saccharomyc ...19989484594
host cell signalling during listeria monocytogenes infection.macrophages and other mammalian cells respond to infection with listeria monocytogenes by the transient or persistent activation of host cell signal transduction pathways. in addition, l. monocytogenes infection influences expression of various host cell genes, some of which may hinder or favour bacterial replication. the observed host cell responses vary with the different subcellular locations inhabited by l. monocytogenes during its intracellular life cycle.19989481817
role of gamma delta t cells in immunity to infectious diseases and the regulation of hematolymphoid cell development.my research interests are twofold. the first is to define the biochemical and molecular mechanisms that regulate hematopoietic cell development. in particular, the role that the cytokine interleukin-2 (il2) plays in regulating the development and selection of lymphocyte progenitor cells, and in myelopoiesis are primary areas of research. the second is to understand the role that gamma delta t cells play in pathogen-induced immune responses and autoimmunity. their involvement in the immune respon ...19989479563
mutagenesis study of the glycosylphosphatidylinositol phospholipase c of trypanosoma brucei.the glycosylphosphatidylinositol phospholipase c (gpi-plc) from trypanosoma brucei is particularly effective in hydrolysing the gpi-anchors of some proteins. the enzyme is inhibited by zn2+ and p-chloromercurylphenylsulphonic acid, both of which can act as sulphydryl reagents, suggesting that a cysteine residue may be important in catalysis. single cysteine to serine mutants have been produced for all eight cysteines in gpi-plc; all the mutants were fully active in vitro and were still susceptib ...19979476790
the occurrence of listeria spp. and salmonella spp. in surface waters.listeria ssp., mainly listeria monocytogenes as well as salmonella spp. are recognized as significant human pathogens. the purpose of this study was to examine the occurrence of listeria spp. and salmonella spp. in surface waters of northern greece and to investigate the correlation of these pathogens with the standard indicator bacteria. a total number of 128 water samples from four rivers and one lake were examined for the presence of listeria, salmonella, total coliforms, faecal coliforms and ...19979468661
the role of actin binding proteins in epithelial morphogenesis: models based upon listeria movement.we summarize recent findings on the organization of the protein actin in eucaryotic cells. in particular we focus on how actin can be used to generate a vectorial force that is required for cell movement. these forces arise from protein molecules that recruit actin to the plasma membrane in such a manner that actin filaments extend outward from the cell body. this type of actin dependent force generation has been described in a nucleation-release model, which is one of several models currently b ...19979468611
lectin reactivity and virulence among strains of listeria monocytogenes determined in vitro using the enterocyte-like cell line caco-2.forty-six cultures of listeria monocytogenes (including clinical, food and collection strains) were serotyped, characterized for motility, haemolysis and phospholipase activities and tested for lectin agglutination using a four-lectin set. lectin reactivity (i.e. agglutination by one or more of the four lectins) was observed in all 12 clinical isolates, 16 of the 23 food isolates and eight of the 11 collection strains. virulence was evaluated in vitro based on strains' ability to invade the huma ...19989467903
[presence of listeria monocytogenes and listeria sp. in fresh and cured sausages. use of different conditions of time and temperature for incubation].two different temperatures for enrichment of listeria monocytogenes and related species have been studied (1) cold enrichment at 4 degrees c (2) enrichment at 30 degrees c (fda method). also, two selective media for isolation were tested: acriflavine-ceftazidime agar (a.c.) and palcam agar. we have studied 72 samples of dry-cured sausage (called 'longaniza') at different stages of maturation: fresh, semi-cured and cured samples. the most efficient method was cold enrichment at 4 degrees c during ...19979467304
mice lacking the murine interleukin-8 receptor homologue demonstrate paradoxical responses to acute and chronic experimental infection with listeria monocytogenes.in this study we demonstrate that mice which lack the murine interleukin-8 receptor homologue exhibit enhanced resistance during the early stage of infection (1-4 days after i.v. challenge with listeria monocytogenes). this result is surprising in that interleukin-8 and other cxc chemokines are key players in the accumulation of inflammatory neutrophils, which is thought to be critical for resistance to listeriosis. paradoxically, some of the interleukin-8 receptor knockout mice that survived ac ...19989466943
evaluation of the rapid cb plus system for identification of corynebacterium species and other gram-positive rods.due to the difficulty of identifying corynebacterium spp. with standard methods, we compared them with the rapid cb plus system (remel, lenexa, kans. [formerly innovative diagnostic systems, norcross, ga.]), which consists of 4 carbohydrate and 14 preformed enzyme tests, for the identification of 98 clinical isolates of corynebacterium sp., other coryneforms, listeria monocytogenes, and 17 atcc strains. forty (95%) of 42 strains of corynebacterium spp. were accurately identified to the species l ...19989466773
activation of natural immune functions by pneumocystis carinii. 19979465880
purification and characterization of anti-listeria compounds produced by geotrichum candidum.geotrichum candidum can produce and excrete compounds that inhibit listeria monocytogenes. these were purified by ultrafiltration, centrifugal partition chromatography, thin-layer chromatography, gel filtration, and high-pressure liquid chromatography, and analyzed by liquid chromatography-mass spectrometry, infrared spectrometry, nuclear magnetic resonance spectrometry, and optical rotation. two inhibitors were identified: d-3-phenyllactic acid and d-3-indollactic acid.19989464426
lacticin 3147, a broad-spectrum bacteriocin which selectively dissipates the membrane potential.lacticin 3147 is a broad-spectrum bacteriocin produced by lactococcus lactis subsp. lactis dpc3147 (m. p. ryan, m. c. rea, c. hill, and r. p. ross, appl. environ. microbiol. 62:612-619, 1996). partial purification of the bacteriocin by hydrophobic interaction chromatography and reverse-phase fast protein liquid chromatography revealed that two components are required for full activity. lacticin 3147 is bactericidal against l. lactis, listeria monocytogenes, and bacillus subtilis; at low concentr ...19989464377
dna vaccination exploits normal biology. 19989461180
[the effect of listeria monocytogenes on the blood system].the influence of l. monocytogenes on the hemopoietic system was studied in mouse experiments. all elements of hemopoiesis were damaged. the most pronounced changes developed in erythropoiesis. this was testified by a decrease in erythrocyte count and hemoglobin content in peripheral blood, by the hypoplasia of the hemopoietic erythroid germ in the marrow, as well as by the decrease of yield in culture cfu-e. these changes in the hemopoietic tissue supposedly caused by the direct action of l. mon ...19979460871
immune privilege in the anterior chamber of the eye is not extended to intraocular listeria monocytogenes.resistance to many pathogens, such as listeria monocytogenes, is correlated with the host's capacity to generate a thi cell-mediated immune response in which delayed-type hypersensitivity (dth) is activated. a wide variety of antigens induce down-regulation of dth when introduced into the anterior chamber of the eye. this immunoregulatory phenomenon has been termed anterior chamber-associated immune deviation (acaid) and is believed to be a primary mechanism for the immune privilege of the anter ...19979455741
comprehensive study of the intestinal stage of listeriosis in a rat ligated ileal loop system.the intestinal stage of listeriosis was studied in a rat ligated ileal loop system. listeria monocytogenes translocated to deep organs with similar efficiencies after inoculation of loops with or without peyer's patches. bacterial seeding of deep organs was demonstrated as early as 15 min after inoculation. it was dose dependent and nonspecific, as the delta inlab, the delta hly, and the delta acta l. monocytogenes mutants and the nonpathogenic species, listeria innocua, translocated similarly t ...19989453636
the role of sialic acid in opsonin-dependent and opsonin-independent adhesion of listeria monocytogenes to murine peritoneal macrophages.the adhesion of listeriae to host cells employs mechanisms which are complex and not well understood. listeria monocytogenes is a facultative intracellular pathogen responsible for meningoencephalitis, septicemia, and abortion in susceptible and immunocompromised individuals. subsequent to colonization and penetration of the gut epithelium, the organism attaches to resident macrophages and replicates intracellularly, thus evading the humoral immune system of the infected host. the focus of these ...19989453618
evidence for expressional crosstalk between the central virulence regulator prfa and the stress response mediator clpc in listeria monocytogenes.virulence is a multifactorial trait which depends on the coordinated expression of many bacterial products, hence it is to be expected that the regulatory circuits that control the relevant genetic determinants are somehow interconnected. two pleiotropic regulatory elements acting at different levels, the transcription factor prfa which controls virulence gene expression and the potential chaperone clpc which is involved in tolerance to environmental stress, are required for listeria monocytogen ...19989453154
prolonged persistence of listeria monocytogenes after intragastric infection in corticosteroid-treated mice.in an attempt to obtain a model more closely resembling natural listeriosis, we studied the course of infection in mice inoculated by the intragastric route with listeria monocytogenes. corticosteroid-treated, and untreated mice both developed subclinical infection without mortality, but faecal shedding and persistence of bacteria in the liver and spleen of corticosteroid-treated mice were significantly more protracted than in untreated mice. untreated mice cleared the bacteria from their livers ...19979451464
interleukin-8 release from human neutrophils after phagocytosis of listeria monocytogenes and yersinia enterocolitica.the release of interleukin-8 (il-8) from human neutrophils was investigated after their internalisation of the invasive bacteria listeria monocytogenes and yersinia enterocolitica. three pairs of bacterial strains were used to study the influence of listeriolysin o, invasiveness and yersinia virulence plasmid (pyv)-encoded proteins on neutrophil cytokine synthesis. the neutrophils secreted il-8 into the culture supernate after exposure to all strains tested. with l. monocytogenes, the virulence ...19989449950
a universal protocol for pcr detection of 13 species of foodborne pathogens in foods.a universal protocol for pcr detection of 13 species of foodborne pathogens in foods was developed. the protocol used a universal culture medium and the same pcr conditions with 13 sets of specific primers. the 13 species of foodborne pathogens examined were escherichia coli, e. coli-etec, e. coli-o157:h7, shigella spp., salmonella spp., yersinia enterocolitica, y. pseudotuberculosis, vibrio cholerae, v. parahaemolyticus, v. vulnificus, listeria monocytogenes, staphylococcus aureus and bacillus ...19979449811
inhibition of listeria monocytogenes by enterocin 4 during the manufacture and ripening of manchego cheese.the inhibitory effect of enterocin 4, a bacteriocin produced by enterococcus faecalis inia 4, on listeria monocytogenes strains ohio and scott a during the manufacture and ripening of manchego cheese was investigated. raw ewe's milk was inoculated with ca 10(5) cfu ml-1 of l. monocytogenes and with 1% of a commercial lactic starter, 1% of an ent. faecalis inia 4 culture, or 1% of each culture. manchego cheeses were manufactured according to usual procedures. listeria monocytogenes ohio counts de ...19979449804
in vitro extracellular and intracellular activity of two newer and two earlier fluoroquinolones against listeria monocytogenes.two new fluoroquinolones (trovafloxacin and sparfloxacin) with enhanced activity against gram-positive pathogens and two earlier compounds (ciprofloxacin and ofloxacin) were tested for their in vitro inhibitory and bactericidal activity against 80 strains of listeria monocytogenes. all strains were uniformly highly susceptible to trovafloxacin, the mic90 being 0.25 mg/l. resistance to sparfloxacin was not detected, however the mic90 of sparfloxacin was eight times that of trovafloxacin. a few st ...19979447905
essential roles for granulocyte-macrophage colony-stimulating factor (gm-csf) and g-csf in the sustained hematopoietic response of listeria monocytogenes-infected mice.the in vivo roles of granulocyte-macrophage colony-stimulating factor (gm-csf) and granulocyte (g)-csf were studied in factor-deficient gene-targeted knockout mice infected with the facultative intracellular bacterium listeria monocytogenes. previous results showed that g-csf-/- mice had an underlying selective deficiency in granulopoiesis, but gm-csf-/- mice had little disturbance in resting hematopoiesis. nevertheless, in this study it is revealed that 3 days after intraperitoneal infection wi ...19989446646
[the computed tomographic and magnetic resonance aspects in meningoencephalitis due to listeria monocytogenes. a case report]. 19979446135
the host response to listeria monocytogenes mutants defective in genes encoding phospholipases c (plca, plcb) and actin assembly (acta).several genes involved in the determination of listeria monocytogenes pathogenesis have been identified. among them, plca gene encodes phosphatidylinositol-specific phospholipase c (pi-plc), plcb gene encodes a broad-range phospholipase c (pc-plc), and acta encodes a protein contributing to actin assembly in infected cells. the interaction of l. monocytogenes wild type (lo 28) strain and two derivative mutants, plca- (bug 206) and acta-/plcb- (lut 12), with macrophages and t lymphocytes was inve ...19979444325
host-pathogen interactions during entry and actin-based movement of listeria monocytogenes.listeria monocytogenes is a pathogenic bacterium that induces its own uptake into mammalian cells, and spreads from one cell to another by an actin-based motility process. entry into host cells involves the bacterial surface proteins inla (internalin) and inlb. the receptor for inla is the cell adhesion molecule e-cadherin. inlb-mediated entry requires activation of the host protein phosphoinositide (pi) 3-kinase, probably in response to engagement of a receptor. actin-based movement of l. monoc ...19979442892
interleukin-12 promotes enhanced resistance to listeria monocytogenes infection of lead-exposed mice.the heavy metal lead (pb) has been shown to downregulate various parameters of cell-mediated immune (cmi) responses. this inhibition of cmi responses by pb is exemplified by a higher mortality rate upon infections with sublethal doses of a variety of pathogens. unlike pb, which lowers host resistance, interleukin-12 (il-12) exerts a substantial stimulatory influence on the host response to intracellular bacteria such as listeria monocytogenes. to explore the influence of il-12 in mice rendered s ...19979439714
effects of gamma irradiation on the survival of listeria monocytogenes and on its growth at refrigeration temperature in poultry and red meat.gamma irradiation sensitivity of a strain of listeria monocytogenes was determined in trypticase soy broth supplemented with yeast extract (tsb-ye), in a slurry of chicken breast meat and in raw ground beef. d10 values in these different media were 0.364, 0.599, and 0.699 kgy, respectively. this organism appeared most sensitive in tsb-ye, more resistant in minced fresh chicken breast meat, and most resistant in fresh minced beef. it was found that irradiation at 2.5 kgy prior to refrigeration is ...19979438279
risk assessment for the harmful effects of uvb radiation on the immunological resistance to infectious diseases.risk assessment comprises four steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization. in this study, the effects of increased ultraviolet b(uvb, 280-315 nm) radiation on immune functions and the immunological resistance to infectious diseases in rats were analyzed according to this strategy. in a parallelogram approach, nonthreshold mathematical methods were used to estimate the risk for the human population after increased exposure to uvb radiati ...19989435148
nisin resistance in listeria monocytogenes atcc 700302 is a complex phenotype.nisin resistance in listeria monocytogenes atcc 700302 is a complex phenotype involving alterations in both the cytoplasmic membrane and the cell wall and a requirement for divalent cations. in addition to a lower ratio of c15 to c17 fatty acids than in the wild-type strain (a. s. mazzotta and t.j. montville, j. appl. microbiol. 82: 32-38, 1997), this nisin-resistant (nisr) strain contained significantly more zwitterionic phosphatidylethanolamine and less anionic phosphatidylglycerol and cardiol ...19989435079
effect of antibacterial antibody on bactericidal activities of superoxide and lysosomal enzyme from alveolar macrophages in rabbits.alveolar macrophages (am) have many fc receptors for igg, but are less reactive to lymphokines. they have a well-developed oxidative metabolism and contain large amounts of lysosomal enzyme. this suggests that the antibacterial antibody plays an important role in early resistance by am to intracellular bacterial infection and that a bactericidal agent, dependent on oxygen and lysosomal enzyme, participates in the effects of the antibacterial antibody on bactericidal activities of superoxide (o2- ...19969434328
[the ecological aspects of listeriosis in the maritime territory].in the process of batch cultivation the strains under study are capable of prolonged growth at low temperature in rich and poor nutrient media (with the term of observation equal to 4 months), while at a temperature of 37 degrees c microbial populations quickly die (in 8-35 days). in the absence of compounds containing carbon, hydrogen and nitrogen in the nutrient medium, listeria can proliferate under such conditions. as established with the use of gas chromatography and the radioisotopic metho ...19979432856
[the gas trophicity of pathogenic bacteria].yersinia pseudotuberculosis and listeria have been shown to be capable of assimilating carbon dioxide from the air and using its carbon for the synthesis of biopolymers of the bacterial cell. these microorganisms, the causative agents of saprozoonotic infections, have also been found to be capable of assimilating molecular nitrogen from the air in small amounts. the data on the influence of the growth conditions of the cultures (hydrogen concentration, the presence of carbon dioxide and oxygen, ...19979432851
[acute hydrocephalus and brain abscess in listeria monocytogenes meningitis]. 19979432203
[presence of various pathogenic microorganisms in fresh vegetables in costa rica].this study reports the occurrence of some pathogenic microorganisms in vegetable consumed on a daily basis by costa ricans. cryptosporidium sp. oocysts were found in 5.2% (4/80) of cilantro leaves, in 8.7% (7/80) of cilantro roots and 2.5% of lettuce samples. a 1.2% (1/80) incidence was found in other vegetables samples (carrot, cucumber, radish and tomatoe). oocysts of this parasite were absent in cabbage. giardia intestinalis was only detected in 5.2% (4/80) of cilantro leaves and in 2.5% (2/ ...19969429609
[effect of different dairy products on the growth of listeria monocytogenes in selective media].we have studied the influence of the incorporation of milk cream and skim milk on the growth kinetic of listeria monocytogenes in listeria enrichment broth with 15 mg/l or 7.5 mg/l of acriflavine. acriflavine was responsible, at least partially, for delayed growth of listeria monocytogenes in the enrichment broths. a longer lag phase of the growth was produced by the addition of milk cream or skim milk to the enrichment broth containing 7.5 mg/l of acriflavine. however, the maximum population ob ...19979424626
[listeria monocytogenes and listeria sp in heat-processed products].presence of listeria monocytogenes in thermoprocessed food which is vacuum packaged, refrigerated stored and eaten uncooked or minimally heated was investigated. thirty samples including sausage, large sausage with ham, spring large sausage, liverwurst and bologna were examined. listeria monocytogenes was isolated and identified according to usda-fsis method for meat products, simultaneously with mcbride agar. seven out of 30 samples were found to contain listeriae. five isolates were identified ...19979424625
listeria monocytogenes virulence factors that stimulate endothelial cells.listeria monocytogenes infection of endothelial cells upregulates surface expression of adhesion molecules and stimulates neutrophil adhesion to infected cell monolayers. the experiments presented here tested the roles of specific bacterial virulence factors as triggers for this inflammatory phenotype and function. human umbilical vein endothelial cell (huvec) monolayers were infected with wild-type l. monocytogenes or l. monocytogenes mutants; then surface expression of e-selectin and neutrophi ...19989423863
comparison of antibody-direct epifluorescent filter technique with the most probable number procedure for rapid enumeration of listeria in fresh vegetables.the antibody-direct epifluorescent filter (ab-deft) technique was evaluated as a rapid alternative to the most probable number (mpn) method for enumeration of artificially inoculated listeria monocytogenes in ready-to-eat packaged salads and other fresh vegetables. ab-deft was performed by homogenization of food in mesh-lined stomacher bags, followed by prefiltration of homogenate through a 5 microns pore nylon filter, and passage of filtrate through a 0.4 micron pore black polycarbonate filter ...19979419860
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