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molecular template for a voltage sensor in a novel k+ channel. i. identification and functional characterization of kvlm, a voltage-gated k+ channel from listeria monocytogenes.the fundamental principles underlying voltage sensing, a hallmark feature of electrically excitable cells, are still enigmatic and the subject of intense scrutiny and controversy. here we show that a novel prokaryotic voltage-gated k(+) (kv) channel from listeria monocytogenes (kvlm) embodies a rudimentary, yet robust, sensor sufficient to endow it with voltage-dependent features comparable to those of eukaryotic kv channels. the most conspicuous feature of the kvlm sequence is the nature of the ...200616908725
molecular template for a voltage sensor in a novel k+ channel. ii. conservation of a eukaryotic sensor fold in a prokaryotic k+ channel.kvlm, a novel bacterial depolarization-activated k(+) (kv) channel isolated from the genome of listeria monocytogenes, contains a voltage sensor module whose sequence deviates considerably from the consensus sequence of a kv channel sensor in that only three out of eight conserved charged positions are present. surprisingly, kvlm exhibits the steep dependence of the open channel probability on membrane potential that is characteristic of eukaryotic kv channels whose sensor sequence approximates ...200616908726
[listeria monocytogenes meningoencephalitis lacking meningeal signs].we report a fatal case of meningoencephalitis due to listeria monocytogenes. a 74-year old alcoholic man presented with high-grade fever lasting for four days without headache and meningeal signs. routine blood analysis showed leukocytosis, but serum c-reactive protein (crp) was not significantly elevated. he developed altered consciousness with focal seizure, and cerebrospinal fluid (csf) examination showed a minor degree of pleocytosis, elevated protein, and hypoglycorrhachia. repeated csf exa ...200616910472
composition of the essential oils of thymus and origanum species from algeria and their antioxidant and antimicrobial activities.the composition of the essential oils of origanum and thymus species restricted to algeria and the north africa region was determined. antioxidant and antibacterial activities of the isolated essential oils were also determined. the oils of oregano plants were strongly characterized by p-cymene (16.8-24.9%), gamma-terpinene (16.8-24.9%), thymol (8.4-36.0%), and carvacrol (1.1-29.7%), a thymol chemotype for origanum floribundum and a alpha-terpineol chemotype for thymus numidicus being described ...200616910725
evaluation of aloa plating medium for its suitability to recover high pressure-injured listeria monocytogenes from ground chicken meat.to evaluate a chromogenic plating medium for the isolation of sublethally injured cells of listeria monocytogenes from processed foods.200616910938
the protein secretion systems in listeria: inside out bacterial virulence.listeria monocytogenes, the etiologic agent of listeriosis, remains a serious public health concern with its frequent occurrence in food coupled with a high mortality rate. the capacity of a bacterium to secrete proteins to or beyond the bacterial cell surface is of crucial importance in the understanding of biofilm formation and bacterial pathogenesis to further develop defensive strategies. recent findings in protein secretion in listeria together with the availability of complete genome seque ...200616911044
prophylactic administration of withania somnifera extract increases host resistance in listeria monocytogenes infected mice.in this study, we demonstrated that withania somnifera l. extract (wse) protects mice from a lethal dose of listeria monocytogenes when administered prophylactically at 100, 250 and 500 mg/kg for 10 days, with survival rates up to 30%. these doses also prevented the myelosuppression and the splenomegaly caused by a sublethal infection with l. monocytogenes, due to increased numbers of granulocyte-macrophage progenitors (cfu-gm) in the bone marrow. investigation of the production of colony-stimul ...200616919825
towards the definition of pathogenic microbe.identification and typing of spoilage and pathogenic microorganisms have become major objectives over the past decade in microbiology. in food, strain typing is necessary to ensure food safety and for linking cases of foodborne infections to suspected items. recent advances in molecular biology have resulted in the development of numerous dna-based methods for discrimination among bacterial strains. here, we present the use of simple sequence repeats (ssr, or microsatellites) for bacterial typin ...200616919836
prophylactic anti-tumor immunity against a murine fibrosarcoma triggered by the salmonella type iii secretion system.the potential of an attenuated salmonella enterica serovar typhimurium strain as a prophylactic anti-tumor vaccine against the murine fibrosarcoma wehi 164 was evaluated. tumor cells were transfected with the dna sequence encoding the mhc class i-restricted peptide p60(217-225) from listeria monocytogenes. balb/c mice received a single orogastric immunization with salmonella that translocates a chimeric p60 protein via its type iii secretion system. mice were subsequently challenged subcutaneous ...200616919987
t cell conditioning explains early disappearance of the memory cd8 t cell response to infection.memory cd8 t cells respond more rapidly to acute intracellular infections than naive cd8 t cells. an understanding of the biological processes involved in memory cd8 t cell recognition of ag and up-regulation of effector mechanism necessitates analyzing memory cd8 t cells at early time points after infection. in the current study, we show that memory cd8 t cells ostensibly disappear from the spleens, blood, and peripheral organs of mice early after infection with listeria monocytogenes. this dis ...200616920937
effectiveness of radiation processing in elimination of salmonella typhimurium and listeria monocytogenes from sprouts.the effectiveness of radiation treatment in eliminating salmonella typhimurium and listeria monocytogenes on laboratory inoculated ready-to-eat sprouts was studied. decimal reduction doses (d10-values) for salmonella typhimurium and l. monocytogenes in dry seeds of mung (green gram), matki (dew gram), chana (chick pea), and vatana (garden pea) ranged from 0.189 to 0.303 kgy and 0.294 to 0.344 kgy, respectively. in sprouts made from these seeds, the d10-values ranged from 0.192 to 0.208 kgy for s ...200616924910
efficacy of selected acidulants in pureed green beans inoculated with pathogens (escherichia coli o157:h7 and listeria monocytogenes).studies were conducted to evaluate the combined effect of selected acidulants (acetic, citric, malic, and phosphoric acid) and heat on foodborne pathogens (escherichia coli o157:h7 and listeria monocytogenes) in pureed green beans. to establish a consistent reference point for comparison, the molar concentrations of the acids remained constant while the acid-to-puree ratio, titratable acidity, and undissociated acid were either measured or calculated for a target acidified green beans at a ph of ...200616924911
selective enrichment media affect the antibody-based detection of stress-exposed listeria monocytogenes due to differential expression of antibody-reactive antigens identified by protein sequencing.selective enrichment broths are frequently used to recover stressed listeria cells to detectable levels, but the ability of antibodies to detect these cells from various commonly used enrichment media is unknown. in this study, a polyclonal (pab) and monoclonal (mab) antibody were used to examine the variation in antigen expression on healthy or stress-recovered listeria monocytogenes cells grown in brain heart infusion broth, buffered listeria enrichment broth (bleb), listeria repair broth (lrb ...200616924913
isolation and preliminary characterization of a bacteriocin produced by lactobacillus plantarum n014 isolated from nham, a traditional thai fermented pork.lactobacillus plantarum n014 was isolated from nham, a traditional thai fermented pork, and exhibited antimicrobial activity against listeria monocytogenes. its bacteriocin had a broad inhibitory spectrum toward both gram-positive and gram-negative bacteria. the bacteriocin activity was sensitive to all proteolytic enzymes used in this study, including papain, pepsin, pronase e, proteinase k, and trypsin, but was resistant to the other enzymes, such as alpha-amylase, lipase a, and lysozyme. furt ...200616924920
production of piscicolin 126 by carnobacterium maltaromaticum ual26 is controlled by temperature and induction peptide concentration.carnobacterium maltaromaticum ual26 produces the antimicrobial peptides (bacteriocins) piscicolin 126, first isolated from c. maltaromaticum jg126, and carnobacteriocin bm1, first isolated from c. maltaromaticum lv17. c. maltaromaticum ual26 is especially inhibitory to strains of listeria monocytogenes. bacteriocin activity is not observable in the supernatant of cultures of ual26 grown in liquid media at 25 degrees c, but at temperatures less than 19 degrees c bacteriocin activity can be detect ...200616927067
elucidation of mechanisms of acid stress in listeria monocytogenes by proteomic analysis. 200616929674
acute and chronic alcohol abuse modulate immunity.this article represents the proceedings of the alcohol and immunology research interest group (airig) meeting, a satellite workshop held at the 37th annual meeting of the society for leukocyte biology. the meeting was sponsored by the airig and the national institute on alcohol abuse and alcoholism. the presentations were as follows: (1) effects of ethanol on immune response to hepatitis c virus by jack r. wands, (2) alcohol and alveolar macrophage dysfunction: the role of chronic oxidant stress ...200616930226
comparison of listeria monocytogenes strain types in irish smoked salmon and other foods.an investigation of listeria monocytogenes in irish retail smoked salmon products and other unrelated food products was undertaken. serotyping and genotyping methods were applied. twenty-six l. monocytogenes isolates cultured from ready-to-eat smoked salmon and an additional 20 l. monocytogenes isolates from various commercially available food products (other than smoked salmon) were compared. four serotypes, 12 ribotypes, 12 amplified fragment length polymorphism (aflp) types and 17 pulsed-fiel ...200616872895
cytoplasmic bacteria and the autophagic pathway.cytoplasmic bacteria may assist in our study of the autophagic pathway. this review highlights the use of listeria monocytogenes for examining the assembly of autophagic vacuoles in mammalian cells. inhibiting protein synthesis of cytoplasmic l. monocytogenes results in their being sequestered into the autophagic pathway. autophagic vacuoles form around the easily identified bacterial particles making the assembly process easy to study using morphological and biochemical methods. l. monocytogene ...200616874112
survival of listeria monocytogenes scott a on metal surfaces: implications for cross-contamination.listeria monocytogenes is an important re-emerging pathogen which is commonly found in the environment. many outbreaks have been associated with the contamination of food produce, often linked to cross-contamination from surfaces or equipment to prepared foodstuffs. in the present study a number of copper-base metal alloys have been used to assess the survival times of l. monocytogenes on different materials, in comparison with stainless steel. high concentrations (10(7)) of bacteria were placed ...200616876278
deformations in actin comets from rocketing beads.the mechanical and dynamical properties of the actin network are essential for many cellular processes like motility or division, and there is a growing body of evidence that they are also important for adhesion and trafficking. the leading edge of migrating cells is pushed out by the polymerization of actin networks, a process orchestrated by cross-linkers and other actin-binding proteins. in vitro physical characterizations show that these same proteins control the elastic properties of actin ...200616877512
genotypes of listeria monocytogenes strains isolated from 2000 to 2002 in poland.pulsed field gel electrophoresis (pfge), multiplex pcr and multilocus sequence typing (mlst) methods were used for genotyping study of seventy-three l. monocytogenes isolates collected in poland between 2000 and 2002 from human, food, environment and a diseased goat. the multiplex pcr, which is an alternative method to classical serotyping, divided the isolates into four pcr groups, iia (42.5%), iib (27.4%), iic (4.1%) and ivb (26%). the isolates displayed 33 distinct pfge profiles. twenty eight ...200616878601
modification of a virulence-associated phenotype after growth of listeria monocytogenes on food.to assess the effect of different foods, which have been implicated or not in cases of listeriosis, on the in vitro virulence-associated phenotype level of different listeria monocytogenes strains.200616882137
listeria monocytogenes induced rac1-dependent signal transduction in endothelial cells.infection of endothelial cells by listeria monocytogenes is an essential step in the pathogenesis of listeriosis. small gtpases of the rho family act as molecular switches in signal transduction. we tested the hypothesis that rho gtpases contribute to the regulation of cytokine expression following l. monocytogenes infection. l. monocytogenes induced release of distinct cc and cxc, as well as th1 and th2 cytokines and growth factors by endothelial cells and activated rhoa and rac1. inhibition of ...200616884694
synergistic effect of tumor necrosis factor-alpha and interferon-gamma on enterocyte shedding of syndecan-1 and associated decreases in internalization of listeria monocytogenes and staphylococcus aureus.syndecan-1 is a heparan sulfate proteoglycan expressed on epithelia, and its ectodomain can be shed into the extracellular milieu, affecting a variety of cellular functions. using two bacteria known to react with heparan sulfate, listeria monocytogenes and staphylococcus aureus, experiments were designed to clarify the effect of syndecan-1 shedding on bacterial internalization by human ht-29 enterocytes. mature enterocytes were incubated with tumor necrosis factor (tnf)-alpha and/or interferon ( ...200616884912
sigmab activation under environmental and energy stress conditions in listeria monocytogenes.to measure sigmab activation in listeria monocytogenes under environmental or energy stress conditions, quantitative reverse transcriptase pcr (taqman) was used to determine the levels of transcripts for the sigmab -dependent opuca and clpc genes in strains having null mutations in genes encoding regulator of sigma b proteins (rsbt and rsbv) and sigma b (sigb) and in the l. monocytogenes wild-type 10403s strain under different stress conditions. the deltasigb, deltarsbt, and deltarsbv strains pr ...200616885265
exposure to salt and organic acids increases the ability of listeria monocytogenes to invade caco-2 cells but decreases its ability to survive gastric stress.the effects of environmental stress exposure on listeria monocytogenes growth and virulence-associated characteristics were investigated. specifically, we measured the effects of temperature (7 or 37 degrees c), ph (5.5 or 7.4), the presence of salt and organic acids (375 mm nacl, 8.45 mm sodium diacetate [sd], 275 mm sodium lactate [sl], or a combination of nacl, sd, and sl), and deletion of sigb, which encodes a key stress response regulator, on the ability of l. monocytogenes to grow, invade ...200616885290
a mutation in the luxs gene influences listeria monocytogenes biofilm formation.using a vibrio harveyi reporter strain, we demonstrated that listeria monocytogenes secretes a functional autoinducer 2 (ai-2)-like signal. a luxs-deficient mutant produced a denser biofilm and attached to a glass surface 19-fold better than the parent strain. exogenous ai-2 failed to restore the wild-type phenotype to the mutant. it seems that an intact luxs gene is associated with repression of components required for attachment and biofilm formation.200616885324
vaccination strategy determines the emergence and dominance of cd8+ t-cell epitopes in a fvb/n rat her-2/neu mouse model of breast cancer.the her-2/neu oncogene has >25 hla epitopes, yet only one fvb/n mouse cd8(+) t-cell epitope has been mapped to date. this epitope has been termed the immunodominant epitope for the fvb/n mouse, but we propose that the vaccination strategy determines the dominance of epitopes. using a series of overlapping peptides, we have mapped another cd8(+) t-cell epitope that emerges in the fvb/n mouse following vaccination with listeria monocytogenes-based vaccines that express fragments of her-2/neu. foll ...200616885378
tnf is important for pathogen control and limits brain damage in murine cerebral listeriosis.cerebral listeriosis is a life-threatening disease. however, little is known about the bacterial virulence factors responsible for the severe course of disease and the factors of the immune system contributing to the control of listeria monocytogenes (lm) or even to the damage of the brain. to analyze the importance of the acta gene of lm, which mediates cell-to-cell spread of intracellular lm, the function of tnf in murine cerebral listeriosis was studied. c57bl/6 mice survived an intracerebral ...200616951360
listeriolysin o-deficient listeria monocytogenes as a vaccine delivery vehicle: antigen-specific cd8 t cell priming and protective immunity.strains of listeria monocytogenes (lm) that are deficient in the virulence factor listeriolysin o (llo) are highly attenuated and are thought not to elicit protective immunity. this failure has been attributed to the inability of the bacterium to enter the host cell cytosol and access mhc class i ag processing machinery. we reexamined this issue using recombinant strains of lm that are deficient in llo but express an additional cd8 t cell epitope derived from lymphocytic choriomeningitis virus. ...200616951364
chlamydia trachomatis infection alters the development of memory cd8+ t cells.the obligate intracellular bacterium chlamydia trachomatis is the most common cause of bacterial sexually transmitted disease in the united states and the leading cause of preventable blindness worldwide. prior exposure to c. trachomatis has been shown to provide incomplete protection against subsequent infection. one possible explanation for the limited immunity afforded by prior c. trachomatis infection is poor activation of chlamydia-specific memory cd8+ t cells. in this study, we examined th ...200616951365
systemic and local cc chemokines production in a murine model of listeria monocytogenes infection.repeated intragastric inoculation of listeria monocytogenes into balb/c mice resulted in prolonged bacteraemia and severe hepatic infection. bacteria could also be isolated from the brain tissue of all experimental mice. during the inflammatory process, chemokine concentrations typically increased at the local site in comparison to the systemic level. the liver-to-serum ratio was more pronounced in the case of macrophage inflammatory protein 1 alpha (mip-1 alpha), suggesting its role in the infl ...200616951491
identification of an essential gene of listeria monocytogenes involved in teichoic acid biogenesis.listeria monocytogenes is a facultative intracellular gram-positive bacterium responsible for severe opportunistic infections in humans and animals. we had previously identified a gene encoding a putative udp-n-acetylglucosamine 2-epimerase, a precursor of the teichoic acid linkage unit, in the genome of l monocytogenes strain egd-e. this gene, now designated lmo2537, encodes a protein that shares 62% identity with the cognate epimerase mnaa of bacillus subtilis and 55% identity with cap5p of st ...200616952950
the interferon response to bacterial and viral infections.type i interferons (ifns) were first described several decades ago as soluble factors that were capable of 'interfering' with viral replication when added to infected cells. type i ifns have been shown to be induced by recognition of viral dna and rna via three distinct pathways: (i) a trif-dependent pathway in macrophages via tlrs 3 and 4; (ii) a myd88-dependent pathway in plasmacytoid dendritic cells (pdcs) via tlrs 7/8 and 9; and (iii) an intracellular recognition pathway utilizing the cytopl ...200616953977
cytosolic entry controls cd8+-t-cell potency during bacterial infection.interaction with host immunoreceptors during microbial infection directly impacts the magnitude of the ensuing innate immune response. how these signals affect the quality of the adaptive t-cell response remains poorly understood. utilizing an engineered strain of the intracellular pathogen listeria monocytogenes that infects cells but fails to escape from the phagosome, we demonstrate the induction of long-lived memory t cells that are capable of secondary expansion and effector function but ar ...200616954391
visible-light-induced bactericidal activity of a nitrogen-doped titanium photocatalyst against human pathogens.the antibacterial activity of photocatalytic titanium dioxide (tio(2)) substrates is induced primarily by uv light irradiation. recently, nitrogen- and carbon-doped tio(2) substrates were shown to exhibit photocatalytic activities under visible-light illumination. their antibacterial activity, however, remains to be quantified. in this study, we demonstrated that nitrogen-doped tio(2) substrates have superior visible-light-induced bactericidal activity against escherichia coli compared to pure t ...200616957236
quencher extension for single nucleotide polymorphism quantification in bacterial typing and microbial community analyses.quencher extension is a novel single-step closed tube real-time method to quantify single nucleotide polymorphisms (snps) in combination with primer extension. a probe with a 5'-reporter is single-base extended with a dideoxy nucleotide containing a quencher if the target snp allele is present. the reaction is measured from the quenching (reduced fluorescence) of the reporter. the relative amount of a specific snp allele is determined from the nucleotide incorporation rate in a thermocycling rea ...200616957351
the sigma factor rpon (sigma54) is involved in osmotolerance in listeria monocytogenes.listeria monocytogenes is able to grow under conditions of high osmolarity. we constructed a deletion mutant of rpon, encoding the alternative sigma factor rpon, and analyzed its response to osmotic stress. in a minimal medium with 4% nacl and 1 mm betaine, the mutant showed a similar growth to that of the parental strain, egd. in the same medium with 4% nacl and 1 m carnitine, the growth rate of the mutant was greatly reduced, when the optical density at 600 nm (od600) at the starting point of ...200616958851
the role of clathrin-dependent endocytosis in bacterial internalization.internalization of bacteria into mammalian host cells has been studied extensively in the past two decades. these studies have highlighted the amazingly diverse strategies used by bacterial pathogens to induce their entry in non-phagocytic cells. the roles of actin and of the whole cytoskeletal machinery have been investigated in great detail for several invasive organisms, such as salmonella, shigella, yersinia and listeria. recent results using listeria highlight a role for the endocytosis mac ...200616962776
combined effect of mild heat and acetic acid treatment for inactivating escherichia coli o157:h7, listeria monocytogenes and salmonella typhimurium in an asparagus puree.this study was conducted to validate combined heat and acid treatments for inactivating escherichia coli o157:h7, listeria monocytogenes and salmonella typhimurium in an acidified brine containing, or pickled, asparagus model food.200617040238
development of macrophages with altered actin organization in the absence of mafb.in the hematopoietic system the bzip transcription factor mafb is selectively expressed at high levels in monocytes and macrophages and promotes macrophage differentiation in myeloid progenitors, whereas a dominant-negative allele can inhibit this process. to analyze the requirement of mafb for macrophage development, we generated mafb-deficient mice and, due to their neonatal lethal phenotype, analyzed macrophage differentiation in vitro, in the embryo, and in reconstituted mice. surprisingly w ...200616943423
the mprf protein is required for lysinylation of phospholipids in listerial membranes and confers resistance to cationic antimicrobial peptides (camps) on listeria monocytogenes.pathogenic bacteria have to cope with defence mechanisms mediated by adaptive and innate immunity of the host cells. cationic antimicrobial peptides (camps) represent one of the most effective components of the host innate immune response. here we establish the function of lmo1695, a member of the virr-dependent virulence regulon, recently identified in listeria monocytogenes. lmo1695 encodes a membrane protein of 98 kda with strong homology to the multiple peptide resistance factor (mprf) of st ...200617042784
influence of particle size on drug delivery to rat alveolar macrophages following pulmonary administration of ciprofloxacin incorporated into liposomes.in order to confirm the efficacy of ciprofloxacin (cpfx) incorporated into liposomes (cpfx-liposomes) for treatment of respiratory intracellular parasite infections, the influence of particle size on drug delivery to rat alveolar macrophages (ams) following pulmonary administration of cpfx-liposomes was investigated. cpfx-liposomes were prepared with hydrogenated soybean phosphatidylcholine (hspc), cholesterol (ch) and dicetylphosphate (dcp) in a lipid molar ratio of 7/2/1 by the hydration metho ...200617043040
changing pattern of human listeriosis, england and wales, 2001-2004.microbiologic and epidemiologic data on 1,933 cases of human listeriosis reported in england and wales from 1990 to 2004 were reviewed. a substantial increase in incidence occurred from 2001 to 2004. ten clusters (60 cases), likely to represent common-source outbreaks, were detected. however, these clusters did not account for the upsurge in incidence, which occurred sporadically, predominantly in patients > or =60 years of age with bacteremia and which was independent of sex; regional, seasonal ...200617073084
a field study of the microbiological quality of fresh produce of domestic and mexican origin.produce is responsible for an increasingly larger proportion of foodborne disease outbreaks. in particular, the globalization of the food supply may introduce new food safety risks and allow widespread distribution of contaminated food, particularly produce. the objectives of this study were to: (i) compare the overall quality of domestic and mexican produce throughout the packing process; (ii) examine changes in microbiological quality of both domestic and mexican produce at each stage of produ ...200617045687
an important role of tyk2 in apc function of dendritic cells for priming cd8+ t cells producing ifn-gamma.tyrosine kinase 2 (tyk2) contributes to the signals triggered by il-12 for ifn-gamma production by nk cells and t cells. we found in this study that tyk2-deficient (-/-) mice showed increased susceptibility at the early stage after an i.p. infection with listeria monocytogenes, accompanied by impaired ifn-gamma production. the numbers of both mhc class ib (h2-m3)- or mhc class ia (kb)-restricted cd8+ t cells producing ifn-gamma and exhibiting cytotoxicity were significantly decreased in tyk2-/- ...200617048270
an in vitro cell-culture model demonstrates internalin- and hemolysin-independent translocation of listeria monocytogenes across m cells.an ability to translocate the mucosal epithelia through m cells provides invasive pathogens with a rapid means of accessing the mucosal lymphoid tissues. in order to determine the role of m cells in listeria monocytogenes infection, we initially assessed colonization of peyer's patch (pp) epithelium in balb/c mice by vibrio cholerae eltor, wild-type l. monocytogenes and an isogenic hemolysin mutant (lo28deltahly). it was observed that both wild-type l. monocytogenes and deltahly showed preferent ...200617049432
community-acquired listeria monocytogenes meningitis in adults.listeria monocytogenes is the third most common cause of bacterial meningitis.200617051485
listeria monocytogenes induces the expression of retinoic acid-inducible gene-i.retinoic acid-inducible gene-i (rig-i) is considered to play a role in innate immunity against virus infections. we showed by immunohistochemical study that rig-i expression is upregulated in vivo in hepatic kupffer cells and in splenic reticular cells of mice infected with listeria monocytogenes. both heat-killed l. monocytogenes and live l. monocytogenes induced the expression of rig-i in cultured raw264.7 murine macrophage-like cells in vitro. rig-i may also be involved in innate immunity aga ...200617053317
listeriosis in portugal: an existing but under reported infection.listeriosis is a rare disease caused by the bacterium listeria monocytogenes, the normal vehicle of which is food. the disease, which is largely confined to its risk groups of pregnant women, the elderly and immunocompromised individuals, has increased in incidence in recent years. in portugal, listeriosis is not a notifiable infection and available data are scarce. the objective of this work was to collate the available information concerning listeriosis in portugal by compiling a retrospective ...200617054782
immunoproteasomes are essential for clearance of listeria monocytogenes in nonlymphoid tissues but not for induction of bacteria-specific cd8+ t cells.microbial infections induce the replacement of constitutive proteasomes by immunoproteasomes (i-proteasomes). i-proteasomes support efficient generation of mhc class i epitopes and influence immunodominance hierarchies of cd8(+) t cells. recently, the function of i-proteasomes in antimicrobial responses was challenged by showing that the lack of i-proteasomes has no effect on induction and function of lymphocytic choriomeningitis virus-specific cd8(+) t cells. here, we show that infection with l ...200617056553
structure of internalin c from listeria monocytogenes.the crystal structure of internalin c (inlc) from listeria monocytogenes has been determined at 2.0 a resolution. several observations implicate inlc in infection: inlc has the same transcriptional activator as other virulence genes, it is only present in pathogenic listeria strains and an inlc deletion mutant is significantly less virulent. while the extended concave receptor-binding surfaces of the leucine-rich repeat (lrr) domains of internalins a and b have aromatic clusters involved in rece ...200617057330
antimicrobial leucocin analogues with a disulfide bridge replaced by a carbocycle or by noncovalent interactions of allyl glycine residues.the type iia bacteriocins are antimicrobial peptides isolated from lactic acid bacteria that act as food preservation agents and have nanomolar activity against pathogens such as listeria monocytogenes. previous reports with mutant bacteriocins indicate that the conserved disulfide bridge between cysteine residues 9 and 14 in bacteriocins such as leucocin a (1) is critical for antibiotic properties, which are mediated by target membrane receptor proteins belonging to the mannose phosphotransfera ...200617076487
cd8 t cell recall responses are regulated by the tissue tropism of the memory cell and pathogen.whether memory cd8 t cells can be reactivated in nonlymphoid tissues is unclear. using mice lacking the spleen, lymph nodes, or both, we show that the secondary t cell response, but not homeostatic maintenance of memory cells, required lymphoid tissue. whereas primary and secondary cd8 t cell responses to vesicular stomatitis virus infection were lymph node dependent, responses to listeria monocytogenes infection were driven primarily in the spleen. memory cell subset reactivation was also regul ...200617082587
cytosolic localization of listeria monocytogenes triggers an early ifn-gamma response by cd8+ t cells that correlates with innate resistance to infection.ifn-gamma is critical for innate immunity against listeria monocytogenes (l. monocytogenes), and it has long been thought that nk cells are the major source of ifn-gamma during the first few days of infection. however, it was recently shown that a significant number of cd44highcd8+ t cells also secrete ifn-gamma in an ag-independent fashion within 16 h of infection with l. monocytogenes. in this report, we showed that infection with other intracellular pathogens did not trigger this early ifn-ga ...200617082632
listeria monocytogenes peritonitis in cirrhotic patients: first description in brazil.two cases of spontaneous bacterial peritonitis (sbp) caused by listeria monocytogenes in cirrhotic patients are reported. in one of the cases, the microorganism was isolated from pleural effusion and ascites. sbp is a serious and common complication of patients with ascites caused by hepatic cirrhosis and the culture of the ascitic fluid is an important tool for the diagnosis and for the more appropriate treatment. although a third generation cephalosporin has usually been employed for empiric t ...200617086320
[regulation of nitrogen metabolism in gram-positive bacteria].we searched for new members of the tnra and glnr regulons controlling assimilation of nitrogen in gram-positive bacteria. we identified the regulatory signals for these transcription factors with consensuses atgtnawwwwwwwtnacat for glnr and tgtnawwwwwwwtnaca for tnra. we described the structure and found new potential members for the tnra/glnr regulons in bacillus subtilis, b. licheniformis, geobacillus kaustophilus, oceanobacillus iheyensis, for the tnra regulon in b. halodurans and for the gln ...200617086994
genetic analysis of bacteriocin 43 of vancomycin-resistant enterococcus faecium.a total of 636 vancomycin-resistant enterococcus faecium (vre) isolates obtained between 1994 and 1999 from the medical school hospital of the university of michigan were tested for bacteriocin production. of the 277 (44%) bacteriocinogenic strains, 21 were active against e. faecalis, e. faecium, e. hirae, e. durans, and listeria monocytogenes. of those 21 strains, a representative bacteriocin of strain vre82, designated bacteriocin 43, was found to be encoded on mobilizable plasmid pdt1 (6.2 kb ...200617088377
surveillance for foodborne-disease outbreaks--united states, 1998-2002.since 1973, cdc has maintained a collaborative surveillance program for collection and periodic reporting of data on the occurrence and causes of foodborne-disease outbreaks (fbdos) in the united states.200617093388
listeria monocytogenes: food-borne pathogen and hygiene indicator.in the past 25 years, listeria monocytogenes has become increasingly important as a food-associated pathogen. most european union countries have an annual incidence of human listeriosis of between two and ten reported cases per million. because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to food-borne illness. listeria monocytogenes infections are responsible for the highest hospitalisation rates (91%) amongst known food-borne pathogens and have ...200617094698
single nucleotide polymorphism analysis of the enterocin p structural gene of enterococcus faecium strains isolated from nonfermented animal foods.the bacteriocins produced by two lactic acid bacteria isolated from nonfermented fresh meat and fish, respectively, and exhibiting a remarkable antilisterial activity, were characterized. bacteriocinogenic strains were identified as enterococcus faecium and the maximum bacteriocin production by both strains was detected in the stationary phase of growth. the activity against listeria monocytogenes was maintained in ph range of 3-7 and was stable in both strains after heating at 100 or 121 degree ...200617103378
the effect of lemon, orange and bergamot essential oils and their components on the survival of campylobacter jejuni, escherichia coli o157, listeria monocytogenes, bacillus cereus and staphylococcus aureus in vitro and in food systems.to investigate the effectiveness of oils and vapours of lemon (citrus limon), sweet orange (citrus sinensis) and bergamot (citrus bergamia) and their components against a number of common foodborne pathogens.200617105553
efficacy of lactic acid against listeria monocytogenes attached to poultry skin during refrigerated storage.the aim of this study was to evaluate the effect of lactic acid washing on the growth of listeria monocytogenes on poultry legs stored at 4 degrees c for 7 days.200617105564
listeria monocytogenes translocates throughout the digestive tract in asymptomatic sheep.ruminants are fed forage which is often contaminated with listeria, and frequently shed listeria monocytogenes with their faeces. the present study was designed to localize the sites of infection in the digestive tract concomitant with listeria faecal excretion in a sheep model. ten listeria-free sheep were inoculated per os with a dose of 10(10) c.f.u. of a pathogenic l. monocytogenes strain. listeria received by two of the ten animals were radiolabelled with (111)indium oxine. the disseminatio ...200617108277
the crystal structure of the bacteriophage psa endolysin reveals a unique fold responsible for specific recognition of listeria cell walls.bacteriophage murein hydrolases exhibit high specificity towards the cell walls of their host bacteria. this specificity is mostly provided by a structurally well defined cell wall-binding domain that attaches the enzyme to its solid substrate. to gain deeper insight into this mechanism we have crystallized the complete 314 amino acid endolysin from the temperate listeria monocytogenes phage psa. the crystal structure of plypsa was determined by single wavelength anomalous dispersion methods and ...200617010991
resistance of listeria monocytogenes biofilms to sanitizing agents in a simulated food processing environment.the objective of this study was to evaluate the resistance of biofilms of listeria monocytogenes to sanitizing agents under laboratory conditions simulating a food processing environment. biofilms were initially formed on stainless steel and teflon coupons using a five-strain mixture of l. monocytogenes. the coupons were then subjected to repeated 24-h daily cycles. each cycle consisted of three sequential steps: (i) a brief (60 s) exposure of the coupons to a sanitizing agent (a mixture of pero ...200617012587
construction of a multiple fluorescence labelling system for use in co-invasion studies of listeria monocytogenes.existing virulence models are often difficult to apply for quantitative comparison of invasion potentials of listeria monocytogenes. well-to-well variation between cell-line based in vitro assays is practically unavoidable, and variation between individual animals is the cause of large deviations in the observed capacity for infection when animal models are used. one way to circumvent this problem is to carry out virulence studies as competition assays between 2 or more strains. this, however, r ...200617014739
h2-m3-restricted t cells participate in the priming of antigen-specific cd4+ t cells.h2-m3-restricted cd8+ t cells provide early protection against bacterial infections. in this study, we demonstrate that activated h2-m3-restricted t cells provide early signals for efficient cd4+ t cell priming. c57bl/6 mice immunized with dendritic cells coated with the mhc class ii-restricted listeriolysin o peptide llo(190-201) (llo) generated cd4+ t cells capable of responding to listeria monocytogenes (lm) infection. inclusion of a h2-m3-restricted formylated peptide fmigwii (fmig), but not ...200617015693
detection of listeria monocytogenes from food samples by pcr after ims-plating.for rapid, accurate and sensitive detection of listeria monocytogenes in food samples, colonies developed on the selective agar (oxford agar) after immunomagnetic separation (ims) were subjected to polymerase chain reaction (pcr) assay with the prf a1-2 primer pair. the proposed assay system was shown experimentally to be capable of specifically detecting the bacteria from food samples contaminated at more than 10(2) cfu/g. however, the enrichment culture after a short period of 16 h with the ap ...200617017131
novel method to identify source-associated phylogenetic clustering shows that listeria monocytogenes includes niche-adapted clonal groups with distinct ecological preferences.while phylogenetic and cluster analyses are often used to define clonal groups within bacterial species, the identification of clonal groups that are associated with specific ecological niches or host species remains a challenge. we used listeria monocytogenes, which causes invasive disease in humans and different animal species and which can be isolated from a number of environments including food, as a model organism to develop and implement a two-step statistical approach to the identificatio ...200617021104
general model, based on two mixed weibull distributions of bacterial resistance, for describing various shapes of inactivation curves.cells of listeria monocytogenes or salmonella enterica serovar typhimurium taken from six characteristic stages of growth were subjected to an acidic stress (ph 3.3). as expected, the bacterial resistance increased from the end of the exponential phase to the late stationary phase. moreover, the shapes of the survival curves gradually evolved as the physiological states of the cells changed. a new primary model, based on two mixed weibull distributions of cell resistance, is proposed to describe ...200617021197
a homolog of bacillus subtilis trigger factor in listeria monocytogenes is involved in stress tolerance and bacterial virulence.molecular chaperones play an essential role in the folding of nascent chain polypeptides, as well as in the refolding and degradation of misfolded or aggregated proteins. they also assist in protein translocation and participate in stress functions. we identified a gene, designated tig, encoding a protein homologous to trigger factor (tf), a cytosolic ribosome-associated chaperone, in the genome of listeria monocytogenes. we constructed a chromosomal delta tig deletion and evaluated the impact o ...200617021213
plasmid dna delivery by d-alanine-deficient listeria monocytogenes.optimal dna vaccine efficacy requires circumventing several obstacles, including low immunogenicity, a need for adjuvant, and the costs of purifying injection grade plasmid dna. bacterial delivery of plasmid dna may provide an efficient and low-cost alternative to plasmid purification and injection. also, the bacterial vector may exhibit potential as an immune adjuvant in vivo. thus, we elected to examine the use of cell-wall-deficient listeria monocytogenes as a dna delivery vehicle in vitro. f ...200617022679
modulation of cell adhesion and motility in the immune system by myo1f.although class i myosins are known to play a wide range of roles, the physiological function of long-tailed class i myosins in vertebrates remains elusive. we demonstrated that one of these proteins, myo1f, is expressed predominantly in the mammalian immune system. cells from myo1f-deficient mice exhibited abnormally increased adhesion and reduced motility, resulting from augmented exocytosis of beta2 integrin-containing granules. also, the cortical actin that co-localizes with myo1f was reduced ...200617023661
[comparison of the antibiotics sensibility pattern of listeria monocytogenes and salmonella spp. strains isolated from food with clinical origin samples].the actual use of antibiotics includes, not just its therapeutic cases, but also for disease prevention and as a growth promoter in animals. these practices have resulted in the propagation of resistance to antibiotics, representing a threat for public health. in this work, the antibiotic sensibility pattern of 20 listeria monocytogenes and 40 salmonella spp. strains, isolated from foodstuff was studied and compared with the antibiotic sensibility patterns of 20 l. monocytogenes and 100 salmonel ...200617024963
cd8alpha+ dendritic cells are required for efficient entry of listeria monocytogenes into the spleen.in addition to their bridging function between innate and adaptive immunity, dendritic cells (dcs) may also contribute to primary resistance against infection. here we analyzed the role of dcs during infection with listeria monocytogenes by performing systemic in vivo depletion of these cells. we showed that cd8alpha(+) dcs were crucial for l. monocytogenes spreading and proliferation in the spleen. efficient and rapid uptake of l. monocytogenes by cd8alpha(+) dcs required the small gtpase rac1 ...200617027298
[listeria monocytogenes meningitis in an immunocompetent child]. 200617029934
increased susceptibility to bacterial superinfection as a consequence of innate antiviral responses.the reason why severe localized or systemic virus infections enhance and aggravate bacterial superinfection is poorly understood. here we show that virus-induced ifn type i caused apoptosis in bone marrow granulocytes, drastically reduced granulocyte infiltrates at the site of bacterial superinfection, caused up to 1,000-fold higher bacterial titers in solid organs, and increased disease susceptibility. the finding that the innate antiviral immune response reduces the antibacterial granulocyte d ...200617030789
molecular evidence for vertical transmission of listeriosis, taiwan.the case is presented of a pregnant woman at the 31st week of gestation with listeria monocytogenes bacteraemia and microabscess formation in the endometrium, who delivered an infant with disseminated infection (meningitis and bacteraemia). the two patients were successfully treated with intravenous ampicillin and gentamicin. molecular typing using random amplified polymorphic dna (rapd) analysis disclosed that three isolates from the mother (blood) and infant (blood and cerebrospinal fluid) had ...200617030924
prevalence and lineages of listeria monocytogenes in chinese food products.this study was undertaken to investigate the prevalence and lineages of listeria monocytogenes in different kinds of food products in local chinese markets.200617032231
detection and characterization of listeria monocytogenes in sao jorge (portugal) cheese production.listeria monocytogenes is a foodborne pathogen that can cause serious invasive disease in humans. because human listeriosis cases have previously been linked to consumption of contaminated cheese, control of this pathogen throughout the cheese production chain is of particular concern. to understand the potential for l. monocytogenes transmission via são jorge cheese, a portuguese artisanal cheese variety that bears a protected denomination of origin classification, 357 raw milk, curd, natural w ...200617033035
isolation of pathogenic listeria monocytogenes in faeces of wild animals in captivity.the isolation of pathogenic listeria spp. in faecal samples of captive wild animals was studied. isolation of the pathogen was attempted from the samples by selective enrichment in university of vermont medium and plating onto dominguez-rodriguez isolation agar, palcam agar and modified mcbride listeria agar. pathogenicity of the isolates was tested by christie, atkins, munch petersen test, phosphotidylinositol-specific phospholipase c assay, mice inoculation test and chick embryo bioassay. list ...200617034860
dna fingerprinting by eric-pcr for comparing listeria spp. strains isolated from different sources in san luis, argentina.in this study, a total of 24 listeria spp. strains were analyzed. twenty-two isolates were obtained in san luis (argentina) from human, animal, and food samples. two types of strains, listeria monocytogenes clip 22762 and listeria innocua clip 74915, were included as reference strains. all isolates were biochemically identified and characterized by serotyping, phage typing, and amplification of the flaa gene by polymerase chain reaction (pcr). repetitive intergenic consensus (eric) sequence-base ...200617037249
rapid actin monomer-insensitive depolymerization of listeria actin comet tails by cofilin, coronin, and aip1.actin filaments in cells depolymerize rapidly despite the presence of high concentrations of polymerizable g actin. cofilin is recognized as a key regulator that promotes actin depolymerization. in this study, we show that although pure cofilin can disassemble listeria monocytogenes actin comet tails, it cannot efficiently disassemble comet tails in the presence of polymerizable actin. thymus extracts also rapidly disassemble comet tails, and this reaction is more efficient than pure cofilin whe ...200617060499
mixture cure model with an application to interval mapping of quantitative trait loci.when censored time-to-event data are used to map quantitative trait loci (qtl), the existence of nonsusceptible subjects entails extra challenges. if the heterogeneous susceptibility is ignored or inappropriately handled, we may either fail to detect the responsible genetic factors or find spuriously significant locations. in this article, an interval mapping method based on parametric mixture cure models is proposed, which takes into consideration of nonsusceptible subjects. the proposed model ...200617063400
effect of ozone on the inactivation of yersinia enterocolitica and the reduction of natural flora on potatoes.fresh vegetables contaminated with yersinia enterocolitica have been implicated in foodborne disease outbreaks. surfaces of vegetables can become contaminated with pathogenic microorganisms through contact with soil, irrigation water, fertilizers, equipment, humans, and animals. one approach to reduce this contamination is to treat fresh produce with sanitizers. in this study, the ability of ozone to inactivate y. enterocolitica inoculated in water and on potato surfaces was evaluated. furthermo ...200617066913
control of listeria monocytogenes in goat's milk and goat's jben by the bacteriocinogenic enterococcus faecium f58 strain.the bacteriocinogenic enterococcus faecium f58 strain, a natural goat's jben cheese isolate, lacks decarboxylase activity involved in most biogenic amine formation. it was also sensitive to 13 antibiotics assayed and free of virulence and vancomycin resistance genes. the f58 strain reached the stationary phase after 12 h of growth in sterile goat's milk, and the production of enterocin f-58 (ent l50) was first detected after 48 h (400 au/ml), thereafter remaining stable up to 5 days. the effecti ...200617066915
linking quantitative exposure assessment and risk management using the food safety objective concept: an example with listeria monocytogenes in different cross-contamination scenarios.a practical approach was used to achieve specified food safety objectives (fsos) by incorporating risk assessment methodology. a series of cross-contamination scenarios at the retail level were evaluated in a spreadsheet and ranked according to their level of risk, and the degree to which they exceeded an fso for listeria monocytogenes (100 cfu/g) was determined. percentiles and analyses of variance were used to identify which scenarios would be most likely not to achieve the fso. it was also po ...200617066917
evaluation of chemical and physical (high-pressure and temperature) treatments to improve the safety of minimally processed mung bean sprouts during refrigerated storage.the objective of this study was to compare the effects of combined high hydrostatic pressure and temperature treatments with different chemical sanitation treatments (water, sodium hypochlorite, and hydrogen peroxide) on the microbiological properties of mung bean sprouts. in a first study, the raw product was subjected to several combined high-pressure and temperature treatments for calculating a mathematical model by a response surface methodology. the number of pressure-temperature (150 to 40 ...200617066918
radiation sensitivity and postirradiation growth of foodborne pathogens on a ready-to-eat frankfurter on a roll product in the presence of modified atmosphere and antimicrobials.intervention technologies including ionizing radiation, antimicrobials, and modified atmospheres (ma) can be used to inhibit the growth of or inactivate foodborne pathogens on complex ready-to-eat foods such as sandwiches. however, the effect of these technologies when used in combination (the hurdle concept) on the survival of foodborne pathogens is unknown. the ability of ionizing radiation to inactivate escherichia coli o157:h7, salmonella, listeria monocytogenes, and staphylococcus aureus in ...200617066924
microbiological evaluation of sprouts marketed in mumbai, india, and its suburbs.a study was undertaken to assess the microbiological quality of sprouts marketed in mumbai and its suburbs. a total of 124 sprout samples of four different legumes--mung (phaseolus aureus), matki (phaseolus aconitifolius), chana (cicer arietinum), and vatana (pisum sativum)--were analyzed over a period of 12 months for aerobic plate counts, coliforms, yeast and mold counts, staphylococci, salmonella, listeria monocytogenes, escherichia coli, e. coli o157:h7, and coagulase-positive staphylococcus ...200617066937
isolation and pulsed-field gel electrophoresis typing of listeria monocytogenes from modified atmosphere packaged fresh-cut vegetables collected in ireland.the incidence of listeria monocytogenes in modified atmosphere packaged fresh-cut fruits and vegetables from chill cabinets of a supermarket in ireland was investigated over a 2-year period. overall, 9.58% of fresh-cut produce was contaminated with listeria spp. various species of listeria were isolated from samples, including l. monocytogenes, l. seeligeri, l. innocua, l. welshimeri, and l. ivanovii. no fruit samples contained detectable l. monocytogenes. overall, a total of 21 l. monocytogenes ...200617066939
effect of high-pressure treatment on the survival of listeria monocytogenes scott a in sliced vacuum-packaged iberian and serrano cured hams.high-pressure treatment is useful for increasing the microbiological safety of ready-to-eat foods. with dry-cured hams, this treatment can be applied to the finished product after slicing and vacuum packaging. the effect of high-pressure treatment on the survival of inoculated listeria monocytogenes scott a and on the sensory characteristics of two spanish dry-cured hams, iberian and serrano, was investigated. ham slices were inoculated with l. monocytogenes at 6 x 10(6) cfu/g and held at 4 degr ...200617066942
[prosthetic knee infection caused by listeria monocytogenes in a woman with rheumatoid arthritis and waldenström s macroglobulinemia].listeria are gram-positive bacilli that can be isolated from soil and in the normal fecal flora of many mammals. it is a uncommon pathogen in the general population, but immunocompromised individuals can develop several focal infections, most notably meningoencephalitis and sepsis. nevertheless, infectious arthritis caused by listeria monocytogenes is a exceptional event. we report a new case of prosthetic knee arthritis due to listeria in a woman with seropositive rheumatoid arthritis and walde ...200617067220
fda approves use of bacteriophages to be added to meat and poultry products. 200617067600
failure of listeria monocytogenes keratitis to respond to topical ofloxacin.the purpose of this case report is to demonstrate the need for identification of the offending pathogen in bacterial keratitis to guide appropriate treatment.200617068464
gliotoxin-mediated suppression of innate and adaptive immune functions directed against listeria monocytogenes.gliotoxin is an immunosuppressive apoptogenic mycotoxin produced by a number of fungi including important human pathogens as aspergillus fumigatus. in order to elucidate the potential role of gliotoxin as immunoevasive fungal virulence factor we studied the effects of gliotoxin on the innate and adaptive t cell-mediated immune response against the facultatively intracellular bacterium listeria monocytogenes. gliotoxin induced apoptosis of bone marrow-derived macrophages, dendritic cells and cd8 ...200617071552
cla-1 and its splicing variant cla-2 mediate bacterial adhesion and cytosolic bacterial invasion in mammalian cells.cd36 and limpii analog 1, cla-1, and its splicing variant, cla-2 (sr-bi and sr-bii in rodents), are human high density lipoprotein receptors with an identical extracellular domain which binds a spectrum of ligands including bacterial cell wall components. in this study, cla-1- and cla-2-stably transfected hela and hek293 cells demonstrated several-fold increases in the uptake of various bacteria over mock-transfected cells. all bacteria tested, including both gram-negatives (escherichia coli k12 ...200617071747
short communication: effect of exopolysaccharide isolated from "viili" on the adhesion of probiotics and pathogens to intestinal mucus.the strong ropy character of the scandinavian fermented milk viili is conferred by the exopolysaccharides (eps) produced by lactococcal strains. these biopolymers can be responsible for some health benefits. we have assessed the influence of the eps fraction isolated from commercial viili on the adhesion of some probiotics and pathogens to human intestinal mucus. concentrations of viili eps greater than 0.1 mg/ml promoted a decrease in adherence of bifidobacterium lactis bb12 and lactobacillus r ...200616772550
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