Publications

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high-pressure processing and antimicrobial biodegradable packaging to control listeria monocytogenes during storage of cooked ham.the efficiency of combining high-pressure processing (hpp) and active packaging technologies to control listeria monocytogenes growth during the shelf life of artificially inoculated cooked ham was assessed. three lots of cooked ham were prepared: control, packaging with alginate films, and packaging with antimicrobial alginate films containing enterocins. after packaging, half of the samples were pressurized. sliced cooked ham stored at 6 degrees c experienced a quick growth of l. monocytogenes ...200817993392
the development of a 'labeless' immunosensor for the detection of listeria monocytogenes cell surface protein, internalin b.electrochemical impedance spectroscopy (eis) is a widely used technique for probing bioaffinity interactions at the surfaces of electrically conducting polymers. eis methods can be employed to investigate 'labeless' detection of analytes via impedimetric transduction. this paper describes the development of a direct immunosensor for the detection of a cell-surface protein on listeria monocytogenes, an extremely important food-borne pathogen. l. monocytogenes are facultative anaerobic, non-sporin ...200817988853
evidence of lethal and sublethal injury in food-borne bacterial pathogens exposed to high-intensity pulsed-plasma gas discharges.to apply scanning electron microscopy, image analysis and a fluorescent viability stain to assess lethal and sublethal injury in food-borne bacteria exposed to pulsed-plasma gas discharges (ppgd).200817983430
epigallocatechin gallate inhibits intracellular survival of listeria monocytogenes in macrophages.epigallocatechin gallate (egcg), the major tea catechin, is known as a potent anti-microbial and anti-tumor compound. the effects of egcg on host defense mechanisms against listeria monocytogenes infection were examined in vitro using mouse peritoneal exudate cells. the study showed that egcg inhibited the intracellular growth of l. monocytogenes in macrophages. the enhancement of in vitro anti-l. monocytogenes activity by egcg is not due to the modulation of reactive oxygen intermediates or the ...200817996193
community-acquired bacterial meningitis in cirrhotic patients.the hospital universitari de bellvitge (barcelona, spain) records all cases of bacterial meningitis in a 120-variable database. the characteristics of bacterial meningitis in cirrhotic patients are not well-known, and all cases of community-acquired bacterial meningitis occurring in cirrhotic patients were therefore identified. during 1977-2002, there were 602 episodes of community-acquired bacterial meningitis in adults, of which 29 (4.8%) occurred in cirrhotic patients. compared to non-cirrhot ...200818005179
controlling listeria monocytogenes in cottage cheese through heterologous production of enterocin a by lactococcus lactis.enterocin a is an example of a class iia bacteriocin with potent anti-listerial activity. this study was initiated with a view to harnessing this activity, through heterologous production by a lactococcal starter strain, to limit levels of listeria monocytogenes in a food (cottage cheese).200818005345
antibacterial activity of a bacteriocin-like substance produced by bacillus sp. p34 that targets the bacterial cell envelope.the objective of this study was to investigate the mode of action of bls p34, a bacteriocin-like substance (bls) produced by a novel bacillus sp. strain p34 isolated from the amazon basin. the effect of the bls was tested against listeria monocytogenes, showing a bactericidal effect at 200 au (activity units) ml(-1), while no inhibition of spore outgrowth of bacillus cereus was observed with a dose of 1,600 au ml(-1). growth of escherichia coli and salmonella enteritidis was inhibited, but only ...200817906937
the non-canonical role of atg family members as suppressors of innate antiviral immune signaling.recent research on autophagy clearly demonstrates that the autophagosome-lysosome pathway plays essential roles in elimination of certain pathogens such as group a streptococcus, mycobacterium tuberculosis, listeria monocytogenes, and herpesvirus. (1-4) we have recently found that a key regulator of the autophagic process, the atg12-atg5 conjugate, associates with the signaling molecules retinoic acid-inducible gene i (rig-i) and interferon-beta promoter stimulator 1 (ips-1), which are essential ...200817921696
purification and identification of the pediocin produced by pediococcus acidilactici mm33, a new human intestinal strain.the aim of this study was to purify and identify the bacteriocin produced by pediococcus acidilactici mm33, a strain previously isolated from human gut.200817927747
differential expression of inlb and acta in listeria monocytogenes in selective and nonselective enrichment broths.to investigate the effect of selective and nonselective media on the expression of acta and inlb proteins in listeria monocytogenes.200817927754
orally administered lactobacillus plantarum reduces pro-inflammatory interleukin secretion in sera from listeria monocytogenes infected mice.lactic acid bacteria have traditionally been thought to have immunomodulating effects. to verify this property, lactobacillus plantarum was orally administered to mice (5 x 107 colony forming units (c.f.u.)), prior to infection with listeria monocytogenes in order to evaluate the host resistance against an infectious micro-organism and to better define the influence of l. plantarum on such responses. balb/c mice were treated daily with l. plantarum or received pbs (sham-treated mice as controls) ...200817894920
simultaneous supratentorial and brainstem abscesses due to listeria monocytogenes.multiple supratentorial abscesses caused by listeria monocytogenes are rare. we report the simultaneous occurrence of multiple supratentorial and brainstem abscesses due to listeria, in a patient under corticotherapy for an exacerbation of ulcerative colitis. mr imaging features before and after successful conservative treatments are depicted. in immunocompromised patients with supratentorial listerial abscesses, the coexistence of brainstem abscedation is exceptional. despite high mortality ass ...200817761284
isolation of the bacillus subtilis antimicrobial peptide subtilosin from the dairy product-derived bacillus amyloliquefaciens.to purify and characterize an antimicrobial protein (bacteriocin) isolated from the dairy product-derived bacillus amyloliquefaciens.200817976171
glycine betaine improves listeria monocytogenes tolerance to desiccation on parsley leaves independent of the osmolyte transporters betl, gbu and opuc.to investigate the effect of glycine betaine (gb) on the survival of listeria monocytogenes on leaf surfaces under low relative humidity (rh).200817976173
the metalloprotease of listeria monocytogenes is activated by intramolecular autocatalysis.the metalloprotease (mpl) of listeria monocytogenes is a thermolysin-like protease that mediates the maturation of a broad-range phospholipase c, whose function contributes to the ability of this food-borne bacterial pathogen to survive intracellularly. mpl is made as a proprotein that undergoes maturation by proteolytic cleavage of a large n-terminal prodomain. in this study, we identified the n terminus of mature mpl and generated mpl catalytic mutants to investigate the mechanism of mpl matur ...200817965168
blockade of endogenous b7-h1 suppresses antibacterial protection after primary listeria monocytogenes infection.b7-h1 (also known as cd274 and pd-l1) is a cosignalling molecule regulating t-cell immunity positively or negatively in vivo. however, little is known about the role of endogenous b7-h1 in bacterial infection. we found that b7-h1 expression was up-regulated in various cell populations including cd4+ and cd8+ t cells, natural killer (nk) cells and macrophages following listeria monocytogenes infection. administration of the antagonistic b7-h1 monoclonal antibody resulted in a significant increase ...200817971153
listeria monocytogenes as novel carrier system for the development of live vaccines.listeria monocytogenes is a facultative intracellular bacterium that enters a variety of non-professional mammalian cells by triggered phagocytosis ("zipper mechanism") and replicates in the cytosol of the infected host cells. therefore, it is a promising vaccine vector for the presentation of passenger antigens to the mhc class ii and especially class i pathways. here, we review recent progress made in our laboratory on the development of novel attenuated l. monocytogenes carrier strains for th ...200817936682
development of a tripartite vector system for live oral immunization using a gram-negative probiotic carrier.the mucosa represents the primary target site and thus the first barrier for most microbial pathogens. nevertheless, nearly all present-day vaccines are applied by an invasive route, target the systemic immune system, and do not confer efficient mucosal protection. currently, mucosal immunity can only be achieved by the delivery of antigens via the mucosal route. therefore, multiple efforts are under way to develop mucosal vaccines and particularly live oral vaccines as these would confer consid ...200817936683
generation and maintenance of listeria-specific cd8+ t cell responses in perforin-deficient mice chronically infected with lcmv.disruption of the perforin gene results in primary immunodeficiency and an increased susceptibility to opportunistic pathogens. perforin-deficient (pko) mice fail to clear primary lymphocytic choriomeningitis virus (lcmv) armstrong, resulting in persistent infection and functional exhaustion of virus-specific cd8+ t cells. cd8+ t cell responses to listeria monocytogenes (lm) challenge within the first week after lcmv infection were diminished in both wt and pko mice, and correlated with enhanced ...200817936870
mesothelin targeted cancer immunotherapy.mesothelin is a tumour differentiation antigen that is normally present on the mesothelial cells lining the pleura, peritoneum and pericardium. it is, however, highly expressed in several human cancers including malignant mesothelioma, pancreatic, ovarian and lung adenocarcinoma. the normal biologic function of mesothelin is unknown but recent studies have shown that it binds to ca-125 and may play a role in the peritoneal spread of ovarian cancer. the limited mesothelin expression in normal tis ...200817945478
listeria monocytogenes is common in wild birds in helsinki region and genotypes are frequently similar with those found along the food chain.to evaluate the prevalence and genetic diversity of listeria monocytogenes in wild birds and to compare the genotypes with isolates previously collected from foods and food processing environments.200817953682
enhancing the antilisterial effect of lactobacillus curvatus cwbi-b28 in pork meat and cocultures by limiting bacteriocin degradation.this work focused on listeria monocytogenes growth inhibition and growth rebound in raw and cooked pork meat inoculated with lactobacillus curvatus strains. during storage of raw meat homogenates in the presence of the bacteriocin-producing strain lactobacillus curvatus cwbi-b28wt, the listeria monocytogenes cfu count was initially reduced to an undetectable level, but a growth rebound occurred after two weeks, coinciding with loss of 70% of the bacteriocin activity present at the end of week 2. ...200822063576
effect of pork lard content on the chemical, microbiological and sensory properties of a typical fermented meat product (pitina) obtained from alpagota sheep.the aim was to investigate the physicochemical, microbiological and sensory properties of pitina, a typical fermented meat product and evaluate the effect of two levels of pork lard content (low fat, lf, 10% vs. high fat, hf, 30%) on its attributes. hf attained lower ph than lf pitina, which reached lower water activity. lab comprised the major flora with substantial counts of micrococci, enterococci and mould and yeast. gram negative enterobacteria were recovered as coliforms and faecal colifor ...200822063596
microbial profiles of frozen trimmings and silver sides prepared at indian buffalo meat packing plants.to assess microbiological quality of buffalo meat trimmings (tt=114) and silver sides (ss=41), samples were collected from four different indian meat packing plants. the aim of this study was: (i) to evaluate standard plate count (spc), psychrotrophic count (ptc), enterococcus feacalis count (efc), staphylococcus aureus count (sac) and escherichia coli count (ecc) and the presence of salmonella spp. and listeria monocytogenes; and (ii) also to determine vero toxic e. coli (vtec) by polymerase ch ...200822063348
microbial safety of meat in the european union.the two most frequently reported zoonotic diseases in humans in the eu in 2005 were campylobacter and salmonella infections with incidences of 51.6 and 38.2 cases per 100,000 population, respectively. reported human infections caused by yersinia spp., verocytotoxigenic escherichia coli, and listeria monocytogenes had comparably lower incidences of 2.6, 1.2 and 0.3 cases per 100,000 population, respectively. meat and meat products are important sources for these infections but knowledge on exactl ...200822062091
purification and characterization of a bacteriocin produced by leuconostoc mesenteroides e131.leuconostoc mesenteroides e131, isolated from greek traditional fermented sausage, prepared without the addition of starters, produces a bacteriocin which is active against the pathogen listeria monocytogenes. the bacteriocin was purified by 50% ammonium sulphate precipitation, cation exchange, and reverse-phase chromatography. bacteriocin is active at ph values between 4.0 and 9.0 and retains activity after incubation for 1h at 100°c. proteolytic enzymes inactivated the bacteriocin after 1h of ...200822063322
challenges to meat safety in the 21st century.the safety of meat has been at the forefront of societal concerns in recent years, and indications exist that challenges to meat safety will continue in the future. major meat safety issues and related challenges include the need to control traditional as well as "new," "emerging," or "evolving" pathogenic microorganisms, which may be of increased virulence and low infectious doses, or of resistance to antibiotics or food related stresses. other microbial pathogen related concerns include cross- ...200822062090
inhibition of salmonella sp. listeria monocytogenes and staphylococcus aureus in cooked ham by combining antimicrobials, high hydrostatic pressure and refrigeration.recontamination of ready-to-eat products such as cooked ham during post-processing may be the cause of outbreaks of food-borne disease. the effectiveness of the combination of high pressure processing (hpp) at 600mpa with the natural antimicrobials nisin and potassium lactate has been evaluated in sliced cooked ham spiked with 4logcfu/g of salmonella sp., listeria monocytogenes and staphylococcus aureus after 3-months of storage at 1 and 6°c. in non-hpp sliced cooked ham, the addition of nisin p ...200822062095
molecular tracking of listeria monocytogenes in an iberian pig abattoir and processing plant.the environment and products from an iberian pig abattoir and processing plant were sampled to investigate the prevalence and genetic diversity of listeria monocytogenes. the organism was not detected in the pig carcasses prior to processing. fresh and dry-cured pork did show detectable levels, always ranging below 100cfu per gram. a total of 163 l. monocytogenes isolates collected during one year were characterized by pcr-based serotyping and pulsed-field gel electrophoresis (pfge) restriction ...200822062102
[biologic therapy and infections].biologic therapy is an important therapeutic arsenal in rheumatic diseases. anti-tnf therapies affect host defenses against infections, since tnf mediates inflammation and modulates cellular immune responses. cases of tuberculosis have been observed in patients treated with tnf antagonists, mainly due to the presence of latent or "dormant" tuberculosis infection (ltb1). other microorganisms responsible for the infectious complications associated with biologic therapy are generally intracellular ...200821794348
characterization and antibiotic susceptibility of listeria monocytogenes isolated from poultry and red meat in morocco.this study was carried out on 426 samples of raw meats collected from butcheries and supermarkets in casablanca, morocco. the samples were examined for the occurrence of listeria species. strains of listeria monocytogenes were characterized by several biochemical tests and confirmed by polymerase chain reaction (pcr). +¦-hemolytic cultures and nonhemolytic isolates were tested for biochemical properties with the listeria api test. among the 43 listeria species isolates; we identified 10 strains ...200821694879
spontaneous bacterial peritonitis caused by infection with listeria monocytogenes.spontaneous bacterial peritonitis is a severe and life-threatening complication in patients with ascites caused by advanced liver disease. the organisms most commonly involved are coliform bacteria and third-generation cephalosporins are the empiric antibiotics of choice. this is an uncommon case of spontaneous bacterial peritonitis caused by listeria monocytogenes in a female patient with liver cirrhosis from autoimmune hepatitis. she did not improve with ceftriaxone and her course was complica ...200821490863
biotechnological applications of listeria's sophisticated infection strategies.listeria monocytogenes is a gram-positive bacterium that is able to survive both in the environment and to invade and multiply within eukaryotic cells. currently l. monocytogenes represents one of the most well-studied and characterized microorganisms in bacterial pathogenesis. a hallmark of l. monocytogenes virulence is its ability to breach bodily barriers such as the intestinal epithelium, the blood-brain barrier as well as the placental barrier to cause severe systemic disease. curiously, th ...200821261856
antimicrobial activities of spice extracts against pathogenic and spoilage bacteria in modified atmosphere packaged fresh pork and vacuum packaged ham slices stored at 4 degrees c.the antimicrobial activity of 14 spice extracts against four common meat spoilage and pathogenic bacteria (listeria monocytogenes, escherichia coli, pseudomonas fluorescens and lactobacillus sake) was screened in cultured media (experiment 1). the results showed that individual extracts of clove, rosemary, cassia bark and liquorice contained strong antimicrobial activity, but the mixture of rosemary and liquorice extracts was the best inhibitor against all four types of microbes. subsequently, m ...200820416570
listeria monocytogenes meningitis in adults. 200821063320
[listeria monocytogenes meningitis in children in france].listeriosis is a serious invasive disease which affects mainly pregnant women, newborns and immunocompromised adults.200819268247
characterization of probiotic carnobacteria isolated from rainbow trout (oncorhynchus mykiss) intestine.to characterize two probiotic carnobacterial isolates, carnobacterium maltaromaticum (b26) and c. divergens (b33), derived from rainbow trout (oncorhynchus mykiss) intestine.200819552776
recognition of salmonella typhimurium by immobilized phage p22 monolayers.phages are promising alternatives to antibodies as the biorecognition element in a variety of biosensing applications. in this study, a monolayer of bacteriophage p22 whose tailspike proteins specifically recognize salmonella serotypes was covalently bound to glass substrates through a bifunctional cross linker 3-aminopropyltrimethoxysilane. the specific binding of salmonella typhimurium to the phage monolayer was studied by enzyme-linked immunosorbent assay and atomic force microscopy. escheric ...200819461940
[pleural and ascitic fluid infection by listeria monocytogenes. report of one case].ascitic and pleural fluids infection by listeria monocytogenes is uncommon. the association of spontaneous bacterial peritonitis and empyema caused by this microorganism has been seldom reported. a 61-year-old male with an alcoholic cirrhosis and an upper right lobectomy for a lung cancer, consulted because of an exacerbation of dyspnea, abdominal pain and fever. listeria-monocytogenes was isolated from ascitic and pleural fluids and from blood cultures. he was successfully treated with ampicill ...200819301777
antimicrobial activity of various extracts of ocimum basilicum l. and observation of the inhibition effect on bacterial cells by use of scanning electron microscopy.the antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of ocimum basilicum l. were studied. these extracts were tested in vitro against 10 bacteria and 4 yeasts strains by the disc diffusion method. the results indicated that the methanol extracts of o. basilucum exhibited the antimicrobial activity against tested microorganisms. while the chloroform and acetone extracts had no effect, the methanol extracts showed inhibition zones against strain ...200820161958
periaortic endograft infection due to listeria monocytogenes treated with graft preservation.a 67-year-old man presented to our hospital with general malaise, fever and diffuse abdominal and lower back pain 7 weeks after endovascular aneurysm repair. blood samples showed a leukocyte count of 10.9 x 10(9)/l and a c-reactive protein of 239 mg/l. the computed tomography (ct)-scan showed fluid collections behind the proximal part of the endovascular graft and dorsal to the aorta. ct-guided translumbar needle aspiration of these collections yielded growth with listeria monocytogenes. prosthe ...200818295117
a "retrocidal" plasmid in enterococcus faecalis: passage and protection.enterococcus faecalis mc4 harbors a 130 kb conjugative, pheromone (ccf10)-responding plasmid, pams1, conferring chloramphenicol, streptomycin and tetracycline resistances. a plasmid-borne class iia bacteriocin (mc4-1) determinant and cognate immunity gene were present, but not expressed in mc4. however, pams1 transfer to e. faecalis jh2-2 (but not to the non-isogenic og1ss) generated the surprising ability to express bacteriocin activity against the plasmid donor, mc4. the bacteriocin target spe ...200818295881
restricted expression of c-type lectin-like natural killer receptors by cd8 t cells in the murine small intestine.the intestinal mucosa represents a challenging environment for cd8+ t cells, which must tolerate nutrient antigens and commensal microorganisms while responding efficiently to pathogens. consequently, specific regulatory mechanisms apply for cd8+ t cells in the intestinal environment, which should also be reflected in a tissue-specific gene expression profile of these cells. this study investigates whether such tissue-specific gene expression can be observed in cd8+ t cells primed during bacteri ...200818298548
detection of sublethal thermal injury in salmonella enterica serotype typhimurium and listeria monocytogenes using fourier transform infrared (ft-ir) spectroscopy (4000 to 600 cm(-1)).fourier transform infrared (ft-ir) spectroscopy (4000 to 600 cm(-1)) was utilized to detect sublethally heat-injured microorganisms: salmonella enterica serotype typhimurium atcc 14028, a gram-negative bacterium, and listeria monocytogenes atcc 19113, a gram-positive bacterium. a range of heat treatments (n= 2) at 60 degrees c were evaluated: 0d (control), 2d, 4d, 6d, and 8d using a d(60 degrees c) (s. enterica serotype typhimurium atcc 14028 = 0.30 min, l. monocytogenes atcc 19113 = 0.43 min). ...200818298736
control of listeria monocytogenes and salmonella anatum on the surface of smoked salmon coated with calcium alginate coating containing oyster lysozyme and nisin.this study investigated the antimicrobial effect of oyster lysozyme with or without nisin added to calcium alginate (caalg) coated on the surface of smoked salmon against listeria monocytogenes and salmonella anatum. l. monocytogenes or s. anatum inoculated smoked salmon samples (1 g) were dipped into caalg with either oyster lysozyme (oysl) or hen egg white lysozyme (hewl), with or without added nisin (n), then stored at 4 degrees c for 35 d. our results indicated that the effectiveness of oyst ...200818298738
inactivation of listeria innocua on frankfurters that contain potassium lactate and sodium diacetate by flash pasteurization.listeria monocytogenes, a psychrotrophic foodborne pathogen, is a recurring postprocess contaminant on ready-to-eat meat (rte) products, including frankfurters. potassium lactate (pl) and sodium diacetate (sda) are fda-approved antimicrobials that inhibit the growth of l. monocytogenes when incorporated into the formulation of fine emulsion sausage. flash (steam) pasteurization (fp) has been shown to reduce levels of l. monocytogenes, and its surrogate l. innocua, on frankfurter surfaces. the ab ...200818298739
comparison of the in vitro efficacies of moxifloxacin and amoxicillin against listeria monocytogenes.listeria monocytogenes is a facultative intracellular bacterium that causes severe infections associated with a high mortality rate. moxifloxacin presents extended activity against gram-positive bacteria and has recently been suggested to be a potential alternative in the treatment of listeriosis. we evaluated the in vitro efficacy of moxifloxacin against l. monocytogenes using a combination of epidemiological and experimental approaches. the median mic of moxifloxacin for a large collection of ...200818299415
quantitative evaluation of interleukin-12 p40 gene expression in peripheral blood mononuclear cells.the heterodimeric cytokine il-12 (composed of a p35 and a p40 subunit) is produced primarily by monocytes, macrophages and b cells. in vitro and in vivo experiments have demonstrated the crucial role of il-12 in initiating and establishing both innate immunity and t cell-mediated resistance to intracellular pathogens, including leishmania donovani, toxoplasma gondii, listeria monocytogenes, and mycobacterium tuberculosis. assessment of cytokine expression has thus become crucial to understand ho ...200818300039
monocyte-mediated defense against microbial pathogens.circulating blood monocytes supply peripheral tissues with macrophage and dendritic cell (dc) precursors and, in the setting of infection, also contribute directly to immune defense against microbial pathogens. in humans and mice, monocytes are divided into two major subsets that either specifically traffic into inflamed tissues or, in the absence of overt inflammation, constitutively maintain tissue macrophage/dc populations. inflammatory monocytes respond rapidly to microbial stimuli by secret ...200818303997
potential antimicrobials to control listeria monocytogenes in vacuum-packaged cold-smoked salmon pâté and fillets.in the wake of recent outbreaks associated with listeria monocytogenes in ready-to-eat foods and an increasing desire for minimally processed foods, there has been a burgeoning interest in the use of natural antimicrobials by the food industry to control this pathogen. the minimum inhibitory concentrations (mics) of nisin and salts of organic acids (sodium lactate (sl), sodium diacetate (sd), sodium benzoate (sb), and potassium sorbate (ps)) against twelve strains of l. monocytogenes in a tsbye ...200818308410
multiple point mutations in virulence genes explain the low virulence of listeria monocytogenes field strains.in order to understand the causes of the low virulence of listeria monocytogenes field strains, five low-virulence strains were analysed. these five strains showed changes in relation to invasion, phosphatidyl-inositol phospholipase c (pi-plc) activity, plaque formation and in vivo virulence. molecular analyses revealed the same mutations in the plca, inla and inlb genes in all five strains. the thr262ala substitution in the pi-plc protein was responsible for the absence of pi-plc activity. this ...200818310040
interactions between food-borne pathogens and protozoa isolated from lettuce and spinach.the survival of salmonella enterica was recently shown to increase when the bacteria were sequestered in expelled food vacuoles (vesicles) of tetrahymena. because fresh produce is increasingly linked to outbreaks of enteric illness, the present investigation aimed to determine the prevalence of protozoa on spinach and lettuce and to examine their interactions with s. enterica, escherichia coli o157:h7, and listeria monocytogenes. glaucoma sp., colpoda steinii, and acanthamoeba palestinensis were ...200818310421
optical tweezers cause physiological damage to escherichia coli and listeria bacteria.we investigated the degree of physiological damage to bacterial cells caused by optical trapping using a 1,064-nm laser. the physiological condition of the cells was determined by their ability to maintain a ph gradient across the cell wall; healthy cells are able to maintain a ph gradient over the cell wall, whereas compromised cells are less efficient, thus giving rise to a diminished ph gradient. the ph gradient was measured by fluorescence ratio imaging microscopy by incorporating a ph-sensi ...200818310432
analysis of time-resolved scattering from macroscale bacterial colonies.we investigate the relationship of incubation time and forward-scattering signature for bacterial colonies grown on solid nutrient surfaces. the aim of this research is to understand the colony growth characteristics and the corresponding evolution of the scattering patterns for a variety of pathogenic bacteria relevant to food safety. in particular, we characterized time-varying macroscopic and microscopic morphological properties of the growing colonies and modeled their optical properties in ...200818315368
listeria monocytogenes activated dendritic cell based vaccine for prevention of experimental tumor in mice.the use of dendritic cells (dcs) as a cellular adjuvant provides a promising approach in immunotherapy of cancer. it has been demonstrated that listeria monocytogenes activated dcs pulsed ex vivo with tumor antigens trigger a systemic th1-biased specific immune response and a single dose of this vaccine will cause a considerable anti tumor immunity.200818319523
application of pcr-sscp for molecular epidemiological studies on the exposure of farm children to bacteria in environmental dust.the environmental exposure of farm children to microorganisms in dust has become a focus of interest, since microbial exposure on farms has been related to a reduced prevalence of asthma and atopic diseases in children. previous studies almost exclusively focused on the determination of microbial counts using conventional culturing or the determination of microbial compounds i.e. endotoxins. in this study pcr-sscp (single-strand conformation polymorphism) was modified for characterising bacteria ...200818321601
role of interleukin-12 in determining differential kinetics of invariant natural killer t cells in response to differential burden of listeria monocytogenes.invariant (i) natural killer (nk) t cells are unique t lymphocytes expressing nkr-p1b/c (nk1.1), which recognize glycolipids, notably alpha-galactosylceramide (alpha-galcer) presented by cd1d. the characteristic phenotype of these inkt cells undergoes dramatic changes following listeria monocytogenes infection, and interleukin (il)-12 is involved in these alterations. here we show that liver inkt cells in mice are differentially influenced by the load of infection. liver alpha-galcer/cd1d tetram ...200818321748
deviation from a strong th1-dominated to a modest th17-dominated cd4 t cell response in the absence of il-12p40 and type i ifns sustains protective cd8 t cells.the differentiation of naive cd4 t cells into specific effector subsets is controlled in large part by the milieu of cytokines present during their initial encounter with ag. cytokines that drive differentiation of the newly described th17 lineage have been characterized in vitro, but the cytokines that prime commitment to this lineage in response to infection in vivo are less clear. listeria monocytogenes (lm) induces a strong th1 response in wild-type mice. by contrast, we demonstrate that in ...200818322221
ifn-beta increases listeriolysin o-induced membrane permeabilization and death of macrophages.type i ifn (ifn-i) signaling is detrimental to cells and mice infected with listeria monocytogenes. in this study, we investigate the impact of ifn-i on the activity of listeriolysin o (llo), a pore-forming toxin and virulence protein released by l. monocytogenes. treatment of macrophages with ifn-beta increased the ability of sublytic llo concentrations to cause transient permeability of the plasma membrane. at higher llo concentrations, ifn-beta enhanced the complete breakdown of membrane inte ...200818322222
antibacterial activity of tannin constituents from phaseolus vulgaris, fagoypyrum esculentum, corylus avellana and juglans nigra.tannins were fractionated from acetonic extract preparations of phenolic compounds from phaseolus vulgaris, fagoypyrum esculentum, corylus avellana and juglans nigra. wide variations in antibacterial activities ranging from mics of 62.5 to 500 microg/ml were apparent. of particular note was a relatively high level of activity (62.5 to 125 microg/ml) for all extracts against listeria monocytogenes.200818325686
microbiological safety of sandwiches from hospitals and other health care establishments in the united kingdom with a focus on listeria monocytogenes and other listeria species.in the united kingdom between 1999 and 2004, there were four outbreaks of listeria monocytogenes infection associated with sandwiches purchased from or provided in hospitals. elderly or immunocompromised individuals and pregnant women are particularly vulnerable to infection; therefore, the focus of this study was on sandwiches served in health care establishments. of 3,249 sandwich samples collected between april 2005 and march 2006, 3.3% were of unsatisfactory microbiological quality because o ...200818326180
antimicrobial activity of lactoferrin against foodborne pathogenic bacteria incorporated into edible chitosan film.the objectives of this research were to develop and characterize edible chitosan film containing lactoferrin as a natural antimicrobial agent, and to investigate the combination effects of lactoferrin with lysozyme in chitosan film against the growth of escherichia coli o157:h7 and listeria monocytogenes. chitosan films containing lactoferrin, lysozyme, or nisin were fabricated, and the antimicrobial concentrations were 0.5, 1, or 2 mg in a circular disc of chitosan film. three concentrations of ...200818326181
growth inhibitory effects of kimchi (korean traditional fermented vegetable product) against bacillus cereus, listeria monocytogenes, and staphylococcus aureus.kimchi is a unique korean traditional vegetable product that is fermented by lactic acid bacteria (lab) and is mainly consumed as a side dish with boiled rice. its main ingredients are brined chinese cabbage, red pepper powder, and fermented fish sauce, and these are combined with many spices such as garlic, green onion, ginger, and some seaweed. the relationship between the concentration of lab or the ph and the growth of three gram-positive foodborne pathogens (bacillus cereus, listeria monocy ...200818326182
foodnet survey of food use and practices in long-term care facilities.foodborne illness is an important problem among the elderly. one risk factor for foodborne illness and diarrhea-associated mortality among the elderly is residence in a long-term care facility (ltcf); thus, these facilities must implement measures to ensure safe food. to assess safe food practices, knowledge, and policies, we used a mailed, self-administered questionnaire to survey food service directors at ltcfs that were certified to receive medicare or medicaid at eight foodborne diseases act ...200818326188
contributions of two-component regulatory systems, alternative sigma factors, and negative regulators to listeria monocytogenes cold adaptation and cold growth.the ability of listeria monocytogenes to grow at refrigeration temperatures is critical for transmission of this foodborne pathogen. we evaluated the contributions of different transcriptional regulators and two-component regulatory systems to l. monocytogenes cold adaptation and cold growth. l. monocytogenes parent strain 10403s and selected isogenic null mutants in genes encoding four alternative sigma factors (sigb, sigh, sigc, and sigl), two regulators of sigmab (rsbt and rsbv), two negative ...200818326199
heat shock induces barotolerance in listeria monocytogenes.the aim of this study was to investigate the effect of heat shock on the resistance of listeria monocytogenes to high pressure processing (hpp). l. monocytogenes atcc 19115 was grown to stationary phase at 15 degrees c and inoculated into whole ultrahigh-temperature milk at approximately 10(7) cfu/ml. milk samples (5 ml) were placed into plastic transfer pipettes, which were heat sealed and then heated in a water bath at 48 degrees c for 10 min. immediately after heat shock, the milk was cooled ...200818326200
listeria monocytogenes internalins bind to the human intestinal mucin muc2.listeria monocytogenes cross the intestinal barrier causing systemic infections with high mortality rates. intestinal infection triggers release of intestinal mucus. we show that three l. monocytogenes internalins, inlb, inlc and inlj all bound to muc2 (the major component of intestinal mucus), but not to the cell surface mucin muc1. binding was strongest to inlb>inlc>inlj (p < 0.001). listerial internalins are characterized by their internalin domain, composed by leucine rich repeats (lrr) foll ...200818327567
[perparation and characterization of the monoclonal antibodies against listeriolysin o].to prepare the monoclonal antibodies (mabs) against listeriolysin o (llo), which is the major virulence factor of listeria monocytogenes.200818328183
inhibition of rock activity allows inlf-mediated invasion and increased virulence of listeria monocytogenes.listeria monocytogenes is an intracellular bacterial pathogen that causes life-threatening disease. the mechanisms used by l. monocytogenes to invade non-professional phagocytic cells are not fully understood. in addition to the requirement of bacterial determinants, host cell conditions profoundly influence infection. here, we have shown that inhibition of the rhoa/rock pathway by pharmacological inhibitors or rna interference results in increased l. monocytogenes invasion of murine fibroblasts ...200818331468
keratinocyte growth factor and androgen blockade work in concert to protect against conditioning regimen-induced thymic epithelial damage and enhance t-cell reconstitution after murine bone marrow transplantation.myeloablative conditioning results in thymic epithelial cell (tec) injury, slow t-cell reconstitution, and a high risk of opportunistic infections. keratinocyte growth factor (kgf) stimulates tec proliferation and, when given preconditioning, reduces tec injury. thymocytes and tecs express androgen receptors, and exposure to androgen inhibits thymopoiesis. in this study, we have investigated whether tec stimulation via preconditioning treatment with kgf and leuprolide acetate (lupron), 2 clinica ...200818334670
on the nature of antimicrobial activity: a model for protegrin-1 pores.we conducted over 150 ns of simulation of a protegrin-1 octamer pore in a lipid bilayer composed of palmitoyloleoyl-phosphatidylethanolamine (pope) and palmitoyloleoyl-phosphatidylglycerol (popg) lipids mimicking the inner membrane of a bacterial cell. the simulations improve on a model of a pore proposed from recent nmr experiments and provide a coherent understanding of the molecular mechanism of antimicrobial activity. although lipids tilt somewhat toward the peptides, the simulated protegrin ...200818335931
crystal structure and standardized geometric analysis of inlj, a listerial virulence factor and leucine-rich repeat protein with a novel cysteine ladder.we report on the crystal structure of the internalin domain of inlj, a virulence-associated surface protein of listeria monocytogenes, at 2.7-a resolution. inlj is a member of the internalin family of listerial cell surface proteins characterized by a common n-terminal domain. inlj bears 15 leucine-rich repeats (lrrs), the same number as in inla, the prototypical internalin family member. the lrrs of inlj differ from those of other internalins by having 21, rather than 22, residues and by replac ...200818343406
qnr-like pentapeptide repeat proteins in gram-positive bacteria.to study the role of qnr-like pentapeptide repeat proteins (prps) from several gram-positive species with quinolone resistance in vitro.200818343805
a comparison between polymeric microsphere and bacterial vectors for macrophage p388d1 gene delivery.the purpose of this study was to compare bacterial and polymeric gene delivery devices for the ability to deliver plasmid dna to a murine macrophage p388d1 cell line.200818343983
survival and growth of foodborne microorganisms in processed and individually wrapped cheese slices.the objectives of the research reported here were to determine the growth, survival, or inactivation of selected microorganisms on individually wrapped processed cheese (iwc) slices stored at 5 degrees c and 22 degrees c, and to compare quality indices. iwc slices were spot-inoculated with foodborne pathogenic bacteria (listeria monocytogenes, staphylococcus aureus, and salmonella spp.), spoilage bacteria (pseudomonas spp. and lactobacillus spp.), and spoilage molds (penicillium spp. and cladosp ...200818348389
virulence of listeria monocytogenes isolated from the cheese dairy environment, other foods and clinical cases.the virulence potential of 51 listeria monocytogenes isolates, including strains from cheese, cheese production environments and from human cases of listeriosis, was evaluated in this study. the isolates were used to infect ht-29 cell monolayers in an in vitro test of virulence, based on a plaque-forming assay (pfa). fifteen selected isolates were used for subcutaneous footpad inoculation in mice and subsequent recovery of the bacterium from the spleen 3 days after inoculation. in the pfa, two i ...200818349357
[neonatal septicemia caused by listeria monocytogenes: report of 6 cases].neonatal listeriosis is a relatively rare but serious disease with a high mortality rate. this study was conducted to analyze the clinical features, treatment, and outcome of 6 cases with listeria monocytogenes septicemia confirmed by positive blood cultures.200818353233
trail deficiency does not rescue impaired cd8+ t cell memory generated in the absence of cd4+ t cell help.ag-specific cd8(+) t cells immunized in the absence of cd4(+) t cell help, so-called "unhelped" cd8(+) t cells, are defective in function and survival. we investigated the role of the proapoptotic molecule trail in this defect. we first demonstrate that trail does not contribute to the cd8(+) t cell response to listeria monocytogenes strain expressing ova (lmova) in the presence of cd4(+) t cells. secondly, we generated mice doubly deficient in cd4(+) t cells and trail and analyzed their cd8(+) ...200818354179
the inflammasome: a key player in the inflammation triggered in response to bacterial pathogens. 200818354318
comparison of primary predictive models to study the growth of listeria monocytogenes at low temperatures in liquid cultures and selection of fastest growing ribotypes in meat and turkey product slurries.this study compared the performance of four primary mathematical models to study the growth kinetics of listeria monocytogenes ribotypes grown at low temperature so as to identify the best predictive model. the parameters of the best-fitting model were used to select the fastest growing strains with the shortest lag time and greatest growth rate. nineteen food, human and animal l. monocytogenes isolates with distinct ribotype were grown at 4, 8, and 12 degrees c in tryptic soy broth and slurries ...200818355671
potential of a nisin-containing bacterial cellulose film to inhibit listeria monocytogenes on processed meats.a bacterially produced cellulose film containing nisin was developed and used in a proof-of-concept study to control listeria monocytogenes and total aerobic bacteria on the surface of vacuum-packaged frankfurters. bacterial cellulose pellicles were produced by gluconacetobacter xylinus k3 in corn steep liquor-mannitol medium and were subsequently purified before nisin was incorporated into them. investigations into the effect of nisin concentrations and contact times on incorporation of nisin i ...200818355672
combination of high-intensity pulsed electric fields with natural antimicrobials to inactivate pathogenic microorganisms and extend the shelf-life of melon and watermelon juices.the effect of high-intensity pulsed electric field (hipef) combined with citric acid (0.5-2.0%, w/v) or cinnamon bark oil (0.05-0.30%, w/v) against populations of escherichia coli o157:h7, salmonella enteritidis and listeria monocytogenes in melon and watermelon juices were evaluated. microbiological shelf-life and sensory attributes were also determined. populations of e. coli o157:h7, s. enteritidis and l. monocytogenes were reduced by more than 5.0log(10)cfu/ml in hipef-processed melon (35kv/ ...200818355673
edible chitosan films on ready-to-eat roast beef for the control of listeria monocytogenes.the use of chitosan as an edible film was evaluated for its antimicrobial activity against listeria monocytogenes (lm) on the surface of ready-to-eat (rte) roast beef. l. monocytogenes, decimally diluted to give an initial inoculation of >6.50logcfu/g, was inoculated onto the surface of rte roast beef cubes, and air-dried. the samples were dipped into chitosan (high or low molecular weights) solutions dissolved with acetic or lactic acid at 0.5% (w/v) or 1% (w/v) then bagged and refrigerated at ...200818355679
rapid culling of the cd4+ t cell repertoire in the transition from effector to memory.requirements for cd4+ t cell memory differentiation were analyzed with adoptively transferred smarta t cell receptor (tcr) transgenic cells specific for alymphocytic choriomeningitis virus (lcmv) epitope. lcmv-induced effector and memory differentiation of smarta cells mimicked the endogenous cd4+ t cell response. in contrast, infection with a recombinant listeria expressing the lcmv epitope, although resulting initially in massive smarta expansion, led to loss of effector function and rapid cel ...200818356084
modeling transfer of listeria monocytogenes from slicer to deli meat during mechanical slicing.listeria monocytogenes has been implicated in several listeriosis outbreaks linked to the consumption of presliced ready-to-eat (rte) deli meats. the possible contamination of sliced rte meats by l. monocytogenes during the slicing process has become a public health concern. the objectives of this study were to investigate the transfer phenomena of l. monocytogenes between a meat slicer and ham slices, and to develop empirical models to describe the transfer during slicing. a six-strain cocktail ...200818361687
[relations of the causative agents of plague and listeriosis during their simultaneous stay in the flea citellophilus tesquorum at different environmental temperatures].experiments were carried out to determine the persistence of a plague microbe with varying praline labeling (isolated in the central caucasian mountain focus of plague in the fleas citellophilus tesquorum of a mountain subspecies) in the contamination of the mixed culture of the plague microbe and listeria. inoculation of fleas with a suspension of a plague microbe and listeriae demonstrates the manifest signs of antagonism between both species of microorganisms. this is evidenced by the reducti ...200818368716
evolution, expression and effectiveness in a cluster of novel bovine beta-defensins.the anti-microbial peptides beta-defensins constitute a large family of innate immune effector molecules, conserved across a wide species range. in this paper, we describe a systematic search of the sequenced bovine genome to characterise this extensive gene family in bos taurus, providing an insight into the pattern of conservation of beta-defensin genes between species. we have sequenced a sub-set of these newly discovered bovine beta-defensin genes and also report expression data for these ge ...200818369613
polyclonal and antigen-specific responses of t cells and t cell subsets.evaluation of the functional responses of t cells is of importance in determining the mechanism(s) of immunodeficiency resulting from chronic alcohol abuse and other conditions that lead to immune dysfunction. mice that are chronically exposed to 20% (w/v) ethanol in water develop immunodeficiency and have t cells with abnormal activation profiles, reduced total numbers, increased cd4/cd8 ratios, and an increased memory/naïve phenotype ratio. these cells also have abnormal antigen-specific respo ...200818369925
bioluminescence imaging to evaluate infections and host response in vivo.the continued prospect of emerging pathogens and recent events including the acceptance of widespread drug resistance and threats of bioterrorism have introduced the necessity be creative in our development of therapies for bacterial infections. many pathogens have both acute and persistent phases. there is a need to understand these pathogens throughout their entire life cycle within the host and determine the role that the host response including innate immunity plays in the establishment and ...200818370150
[identification of proteins determining the virulence of listeria monocytogenes using the bioinformation analysis].the postgenomic stage of biotechnology allows the bioinformation approaches to be used for revealing previously unknown factors involved in different processes. in this work, bioinformation approaches were applied to analysis of factors involved in the l. monocytogenes virulence. several open reading frames (orfs) were identified in l. monocytogenes genome, which encode proteins with high level homology to bacterial peptidases and which meets the developed criteria. the influence of the orfs on ...200818376476
the antimicrobial efficacy of plant essential oil combinations and interactions with food ingredients.the objective of this study was to evaluate the efficacy of plant essential oils (eos) in combination and to investigate the effect of food ingredients on their efficacy. the eos assessed in combination included basil, lemon balm, marjoram, oregano, rosemary, sage and thyme. combinations of eos were initially screened against bacillus cereus, escherichia coli, listeria monocytogenes and pseudomonas aeruginosa using the spot-on-agar test. the influence of varying concentrations of eo combinations ...200818378032
assessing genetic heterogeneity within bacterial species isolated from gastrointestinal and environmental samples: how many isolates does it take?strain typing of bacterial isolates is increasingly used to identify sources of infection or product contamination and to elucidate routes of transmission of pathogens or spoilage organisms. usually, the number of bacterial isolates belonging to the same species that is analyzed per sample is determined by convention, convenience, laboratory capacity, or financial resources. statistical considerations and knowledge of the heterogeneity of bacterial populations in various sources can be used to d ...200818378649
effect of antimicrobial peptides divergicin m35 and nisin a on listeria monocytogenes lsd530 potassium channels.the aim of this work was to study the effect of antimicrobial peptides: divergicin m35 and nisin a on listeria monocytogenes lsd 530 potassium (k+) channels: atp-sensitive (k atp), calcium-activated (bk ca), and depolarization-activated (kv) types. increase on k+ efflux and inhibition of cellular growth were observed after adding k+ channel activators pinacidil, ns1619, and cromakalim to divergicin m35. increase in k+ efflux from log-phase cells was about 18 +/- 1.1, 11 +/- 0.63, and nmol mg(-1) ...200818379845
attenuated listeria infection activates natural killer cell cytotoxicity to regress melanoma growth in vivo.listeria monocytogenes infection induces various types of immune responses. the lm-induced immunity not only protects the hosts against lm infection but also has a therapeutic effect on other diseases such as tumors and infectious diseases. in the present study, we sought to identify the cells and molecules that are primarily responsible for the lm-induced antitumor immune response. we investigated the mechanism of the antitumor immune response induced by lm infection using melanoma cells and va ...200818380808
using oligonucleotide suspension arrays for laboratory identification of bacteria responsible for bacteremia.the aim of this study was to develop and validate an oligonucleotide suspension array for rapid identification of 15 bacterial species responsible for bacteremia, particularly prevalent in chinese hospitals. the multiplexed array, based on the qiagen liquichip workstation, included 15 oligonucleotide probes which were covalently bound to different bead sets. pcr amplicons of a variable region of the bacterial 23s rrna genes were hybridized to the bead-bound probes. thirty-eight strains belonging ...200818381803
testing human biologicals in animal host resistance models.the purpose of immunotoxicity testing is to obtain data that is meaningful for safety assessment. host resistance assays are the best measure of a toxicant's effect on the overall ability to mount an effective immune response and protect the host from infectious disease. an outline is presented for immunotoxicological evaluation using host resistance assays. the influenza virus host resistance model is useful to evaluate the overall health of the immune system and is one of the most thoroughly c ...200818382855
mechanical properties of a gelidium corneum edible film containing catechin and its application in sausages.we prepared an edible gelidium corneum (gc) film containing catechin and examined the microbial growth and quality change during storage of sausages packaged with the film. incorporation of catechin in the film improved film tensile strength and water vapor permeability. the film's antimicrobial activity against eschericha coli o157:h7 increased with increasing catechin concentrations and resulted in a decrease in the populations of the bacteria by 1.93 log cfu/g at 150 mg of catechin. for the s ...200818387102
biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging.biodegradable polylactic acid (pla) polymer was evaluated for its application as a material for antimicrobial food packaging. pla films were incorporated with nisin to for control of foodborne pathogens. antimicrobial activity of pla/nisin films against listeria monocytogenes, escherichia coli o157:h7, and salmonella enteritidis were evaluated in culture media and liquid foods (orange juice and liquid egg white). scanned electron micrograph and confocal laser microscopy revealed that nisin parti ...200818387115
multi-method approach indicates no presence of sub-lethally injured listeria monocytogenes cells after mild heat treatment.application of mild inactivation treatments follows an increasing trend in the food industry and is often combined with sub-optimal intrinsic product conditions to ensure appropriate level of microbial safety. listeria monocytogenes was subjected to mild heat treatment (20 min at 60 degrees c) and subsequently exposed to various mild preservation conditions based on increased nacl concentration and decreased ph. recovery and resuscitation of l. monocytogenes cells were studied using various meth ...200818387685
constitutive crosspresentation of tissue antigens by dendritic cells controls cd8+ t cell tolerance in vivo.immature dendritic cells (dcs) sample tissue-specific antigens (tsas) and process them for "crosspresentation" via major histocompatibility complex (mhc) class i and ii molecules. findings with adoptively transferred t cell receptor (tcr)-transgenic cd8+ t cells in transgenic mice expressing model tsa indicate that this process contributes to tolerance induction of cd8+ t cells, a phenomenon termed "crosstolerance." however, up to now it has been unknown whether "crosstolerance" can also control ...200818387832
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