Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| models of invasion of enteric and periodontal pathogens into epithelial cells: a comparative analysis. | bacterial invasion of epithelial cells is associated with the initiation of infection by many bacteria. to carry out this action, bacteria have developed remarkable processes and mechanisms that co-opt host cell function and stimulate their own uptake and adaptation to the environment of the host cell. two general types of invasion processes have been observed. in one type, the pathogens (e.g., salmonella and yersinia spp.) remain in the vacuole in which they are internalized and replicate withi ... | 1997 | 9391752 |
| the interleukin 1beta-converting enzyme, caspase 1, is activated during shigella flexneri-induced apoptosis in human monocyte-derived macrophages. | shigella, the etiological agent of bacillary dysentery, rapidly kills human monocyte-derived macrophages in vitro. wild-type shigella flexneri, but not a nonvirulent derivative, induced human macrophage apoptosis as determined by morphology and terminal deoxynucleotidyltransferase-mediated dutp-biotin nick end labeling (tunel). shigella-mediated macrophage cell death was blocked by the peptide inhibitors of caspases, acetyl-tyr-val-ala-asp-aldehyde (acetyl-yvad-cho) and acetyl-tyr-val-ala-asp-ch ... | 1997 | 9393811 |
| microbiological screening of indian medicinal plants with special reference to enteropathogens. | the world health organisation (who) has recommended that all member states actively promote native medicines in their country. ten indian medicinal plants were screened for antibacterial activity specific to enteropathogens. diffusion and dilution methods were used to measure the antibacterial activity. allium sativum, camellia sinensis, and chamaesyce hirta showed higher activity when compared to the rest. they had a minimum bactericidal concentration (mbc) of < 100 micrograms/ml and gave inhib ... | 1997 | 9395690 |
| the finm promoter and the tram promoter are the principal promoters of the tram gene of the antibiotic resistance plasmid r100. | finp multicopy repression and traj multicopy derepression indicate that the ratio of sense to antisense transcripts is important in the regulation of r100 conjugation. the extension of r100 tram transcripts into traj shows that promoters in tram can affect this ratio, making the regulation of tram transcription important in the regulation of r100 conjugation. since r100 tram, tray and tral proteins bind to the tram promoter region, we examined tram transcription in r100-1 tram, tray and tral mut ... | 1997 | 9402017 |
| [epidemiological characteristics of outbreaks of diarrhea and food poisoning in the israel defense forces in the years 1978-1995]. | acute infectious diseases of the gastrointestinal tract and food poisoning are problems of great importance in the israel defense forces (idf). they involve individual and epidemic morbidity, with impairment of health of individual soldiers and in the activities of units. outbreaks of gastrointestinal infectious diseases must be reported to the idf army health branch, which conducts epidemiological investigation. this study is based on data from yearly epidemiological reports for 1978-1989, and ... | 1997 | 9418352 |
| survival and detection of shigella flexneri in vegetables and commercially prepared salads. | the normal bacterial microflora of 4 commercially prepared salads (coleslaw, crab salad, carrot salad, and potato salad) and 3 vegetables (green pepper, onion, and cabbage) were evaluated. twenty-eight species of bacteria, including potential pathogens, were isolated. the foods were artificially inoculated with an avirulent mutant strain of shigella flexneri 5 (phs1059) to develop a method for the rapid detection of shigella spp. bacteria were separated from insoluble and particulate salad ingre ... | 1997 | 9419858 |
| immunogenicity of ipac-hybrid proteins expressed in the shigella flexneri 2a vaccine candidate sc602. | we have investigated the capacity of live attenuated shigella flexneri strains to act as vectors for the induction of local and systemic antibody responses against heterologous epitopes. the s. flexneri ipac antigen was selected as a carrier protein into which the c3 neutralizing epitope of the poliovirus vp1 protein was inserted in eight sites distributed along ipac. the resulting ipac-c3 hybrid proteins were expressed from recombinant plasmids in the s. flexneri 2a vaccine candidate, sc602. th ... | 1998 | 9423842 |
| rfah and the ops element, components of a novel system controlling bacterial transcription elongation. | the rfah protein controls the transcription of a specialized group of escherichia coli and salmonella operons that direct the synthesis, assembly and export of the lipopolysaccharide core, exopolysaccharide, f conjugation pilus and haemolysin toxin. rfah is a specific regulator of transcript elongation; its loss increases transcription polarity in these operons without affecting initiation from the operon promoters. the operons of the rfah-dependent regulon contain a short conserved 5' sequence, ... | 1997 | 9426123 |
| mechanism of bacteriophage sfii-mediated serotype conversion in shigella flexneri. | we have isolated the lysogenic bacteriophage sfii, which mediates glucosylation of shigella flexneri o-antigen, resulting in expression of the type ii antigen. sfii belongs to group a of the bradley classification and has a genome size of 42.3kb. dna sequencing of a 4 kb bamhi subclone identified four open reading frames (orfs), of which only two were found to be necessary for serotype conversion. these genes were named bgt, which encodes a putative bactoprenol glucosyl transferase, and gtrii, e ... | 1997 | 9426131 |
| [the gas trophicity of pathogenic bacteria]. | yersinia pseudotuberculosis and listeria have been shown to be capable of assimilating carbon dioxide from the air and using its carbon for the synthesis of biopolymers of the bacterial cell. these microorganisms, the causative agents of saprozoonotic infections, have also been found to be capable of assimilating molecular nitrogen from the air in small amounts. the data on the influence of the growth conditions of the cultures (hydrogen concentration, the presence of carbon dioxide and oxygen, ... | 1997 | 9432851 |
| lack of reactivation of shigellosis in naturally infected enrofloxacin-treated cynomolgus monkeys after exogenous immunosuppression. | four cynomolgus macaques housed at our facility became acutely ill with dysenteric symptoms. enteric isolates established an etiologic diagnosis of shigella flexneri. enrofloxacin antimicrobial therapy cleared the infection with no perceptible bacterial shedding or clinical signs of disease. high-dose methyl-prednisolone therapy was administered to the four monkeys for 5 weeks. the animals were monitored for signs of shigellosis and bacterial shedding weekly throughout the study, for a total of ... | 1997 | 9433696 |
| identification and molecular characterization of a 27 kda shigella flexneri invasion plasmid antigen, ipaj. | shigella species and enteroinvasive escherichia coli contain a core set of virulence genes whose coordinated expression results in the invasion of host colonic epithelial cells and the dysenteric syndrome. a number of virulence determinants are carried by the 230 kb invasion plasmid found in all virulent strains of shigellae. many of these invasion plasmid genes encode immunogens that are recognized by convalescent serum, including proteins that mediate the invasion (ipab, ipac, ipad) and cell s ... | 1997 | 9441862 |
| characterization of serum antibody response to chlamydiae in patients with sexually acquired reactive arthritis. | sera from patients with sexually acquired reactive arthritis (sara) with antibodies reacting with c. trachomatis and c. pneumoniae (group 1; n = 20) and also with c. psittaci (group 2; n = 19) were analyzed for antibody specificity. sera from group 2 reacted significantly more often with c. trachomatis serotype e, h and k and had higher antibody titers to serotype e, as tested by microimmunofluorescence tests. cross-reactivities occurring in microimmunofluorescence tests were related to the pres ... | 1997 | 9453389 |
| intracellular multiplication and virulence of shigella flexneri auxotrophic mutants. | we have constructed and analyzed a group of shigella flexneri 5 auxotrophic mutants. the wild-type strain m90t was mutagenized in genes encoding enzymes involved in the synthesis of (i) aromatic amino acids, (ii) nucleotides, and (iii) diaminopimelic acid. in this way, strains with single (arob, aroc, arod, pure, thya, and dapb) and double (pure arob, pure aroc, pure arod, pure thya) mutations were obtained. although the aro mutants had the same nutritional requirements when grown in laboratory ... | 1998 | 9453608 |
| [differences in the cellular surface of hybrid escherichia coli k12 bacteria inheriting the rfb a3,4 gene of shigella flexneri detected using atomic-force microscopy]. | the cell surface of e. coli initial parent strain k12 j62 his-, chemotype ra, and e. coli transductant strain k12 j62 his+, acquiring the capacity for synthesizing primary s-specific side chains of the lipopolysaccharide of s. flexneri o-antigen (group-specific factor 3,4), was studied by the method of atomic force microscopy. the comparative analysis of the images of the genetically linked pair of e.coli strains k12 j62 revealed the presence of essential differences in the topography of the sur ... | 1997 | 9460857 |
| [the clinico-pathogenetic significance of the outer membrane proteins determined by the invasiveness plasmid in flexner's shigellosis]. | s. flexneri 2a outer membrane proteins of 38, 43, 62 and 78 kd, determined by the 140 md invasiveness plasmid, serving as antigens and specific rabbit sera serving as antibodies were used for diagnosing s. flexneri infection in the enzyme immunoassay. the examination of 96 patients and 20 healthy donors showed the possibility of the detection of s. flexneri 2a protein invasins and antibodies to them at different periods of the disease. during the severe course of shigellosis a higher level of pr ... | 1997 | 9460875 |
| [toxic food infection caused by shigella flexneri in a military unit]. | food borne disease outbreaks have increased in france, but outbreaks caused by shigella are rare, accounting for only 73 cases (1.62%) in 1993. we report a food borne outbreak of shigella flexneri strain 3 infection in a fire fighting unit in paris between july 13th and 17th 1995. forty of the 127 firemen suffered symptoms including acute diarrhea (80%), fever (50%) and blood and mucus in stools (1 case, 2.5%). epidemiological investigation generated an unimodal epidemic curve suggesting a singl ... | 1997 | 9480034 |
| a chloride-inducible acid resistance mechanism in lactococcus lactis and its regulation. | previously, a promoter was identified in lactococcus lactis that is specifically induced by chloride. here, we describe the nucleotide sequence and functional analysis of two genes transcribed from this promoter, gadc and gadb. gadc is homologous to putative glutamate-gamma-aminobutyrate antiporters of escherichia coli and shigella flexneri and contains 12 putative membrane-spanning domains. gadb shows similarity to glutamate decarboxylases. a l. lactis gadb mutant and a strain that is unable to ... | 1998 | 9484886 |
| [treatment of severe dysentery]. | the paper presents analysis of clinical efficacy of etiotropic drugs in severe flexner's dysentery chosen by sensitivity of the causing agent, schemes of antibacterial drugs of choice in the treatment of this disease, principles of detoxication therapy. use of bacterial biological drugs in combined treatment of dysentery is validated. | 1997 | 9490365 |
| structural determination of the o-antigenic polysaccharide from the enterotoxigenic escherichia coli o147. | the structure of the o-antigenic polysaccharide from enterotoxigenic escherichia coli o147 has been determined by nmr spectroscopy, and component and methylation analyses. the sequence of the sugar residues could be determined by noesy and heteronuclear-multiple-bond-connectivity nmr experiments. it is concluded that the polysaccharide is composed of tetrasaccharide repeating units with the following structure: -->4)-beta-d-galpa-(1-->3)-beta-d-galpnac-(1-->2)-alpha-l-rhap+ ++-(1-->2)-alpha-l-rh ... | 1998 | 9492329 |
| [scanning electronic microscopy of the small intestine in persistent diarrhea]. | persistent diarrhea very often leads children to malnutrition. it has become the major cause of death resulting from acute diarrhea episodes in developing countries. in order to determine the ultrastructural alterations of the small bowel that occur in the syndrome, 16 infants with severe persistent diarrhea were studied, utilizing light microscopy and the scanning electron microscope. stool and jejunal fluid samples were collected for culture, rotavirus, ova and parasite search. enteropathogeni ... | 1997 | 9496427 |
| phylogenetic analysis and identification of shigella spp. by molecular probes. | oligonucleotide probes were used for identification of shigella and analysis of the relationship between shigella spp. and escherichia coli. probe-based pcrs shown cross-reactions from shigella to e. coli. probe-based 16s rrna sequencing and phylogenetic analysis showed the four species of shigella: sh. dysenteriae, sh. boydii, sh. sonnei, and sh. flexneri, formed a cluster with e. coli. shigella flexneri and sh. sonnei are even more similar to e. coli than to the other two shigella species. the ... | 1997 | 9500811 |
| "black holes" and bacterial pathogenicity: a large genomic deletion that enhances the virulence of shigella spp. and enteroinvasive escherichia coli. | plasmids, bacteriophages, and pathogenicity islands are genomic additions that contribute to the evolution of bacterial pathogens. for example, shigella spp., the causative agents of bacillary dysentery, differ from the closely related commensal escherichia coli in the presence of a plasmid in shigella that encodes virulence functions. however, pathogenic bacteria also may lack properties that are characteristic of nonpathogens. lysine decarboxylase (ldc) activity is present in approximately 90% ... | 1998 | 9520472 |
| antimicrobial resistance in shigella flexneri and shigella sonnei in hong kong, 1986 to 1995. | three hundred and thirty-three shigella isolates obtained in 1986 to 1995 were tested for their susceptibilities to 19 antimicrobial agents. nalidixic acid resistance had emerged in 59.6% of shigella flexneri isolates during 1994 to 1995, with all tested resistant isolates having the mutation in gyra encoding the ser-83 alteration. multiresistance (resistance to four or more agents) was more common in s. flexneri than in shigella sonnei. | 1998 | 9527803 |
| an essential role for gamma interferon in innate resistance to shigella flexneri infection. | shigella spp. are the major cause of bacillary dysentery worldwide. to identify immune effectors associated with protection of the naive host during infection, the susceptibility to pulmonary shigella infection of each of various mouse strains that have a targeted deletion in a specific aspect of the immune system was evaluated. our results demonstrate that mice deficient in gamma interferon are 5 orders of magnitude more susceptible to shigella than are wild-type mice, whereas mice deficient in ... | 1998 | 9529051 |
| increasing incidence of antibiotic resistance in shigellas from humans in england and wales: recommendations for therapy. | since 1983 the incidence of resistance to ampicillin in shigella dysenteriae, sh. flexneri, and sh. boydii infections in england and wales has increased from 42% to 65% and the incidence of resistance to trimethoprim, from 6% to 64%. furthermore, of 1524 strains received in 1995-1996, 46% were resistant to both of these antimicrobials. for sh. sonnei almost 50% of isolates were resistant to ampicillin or trimethoprim and 15% were resistant to both of these antimicrobials. these results demonstra ... | 1998 | 9533726 |
| identification of a novel salmonella invasion locus homologous to shigella ipgde. | genes essential for salmonella typhimurium invasion have been localized to salmonella pathogenicity island 1 (spi1) on the chromosome. however, it is clear that other genes are required for the invasion process. mutations that abolish the spi1 invasion type iii secretion system do not significantly reduce invasion into chinese hamster ovary tissue culture cells. two invasion defective mutants were isolated by screening 2,500 tn10dtc insertion mutants of s. typhimurium in the tissue culture invas ... | 1998 | 9537377 |
| the in situ infrared microspectroscopy of bacterial colonies on agar plates. | the specular reflectance infrared spectra of thirty species of bacteria were obtained in situ, without their removal from the agar growth media, using the infrared microscope. compared to transmittance spectra obtained from dehydrated films, the transformed reflectance spectra show significant band shifts which are greater for gram positive bacteria. the most notable shift occurs in the v[a](po2-) band which shifts 8 cm(-1) higher upon removal of water. in addition, some measure of the different ... | 1998 | 9551654 |
| plasmid profile analysis and restriction enzyme analysis in characterizing shigella flexneri isolates from an outbreak. | shigella flexneri strains which are multiply resistant to antimicrobial agents were isolated from 11 children from an orphanage in cluj-napoca during an epidemiological investigation initiated by the department of epidemiology. plasmid profile analysis and restriction endonuclease analysis were used in conjunction with biotyping, serotyping and antimicrobial susceptibility testing for identifying epidemiological related isolates. all strains were serotype 2a and with one exception all of them sh ... | 1996 | 9558965 |
| macrophage apoptosis in microbial infections. | upon infection with a pathogen, eukaryotic cells can undergo programmed cell death as an ultimate response. therefore, modulation of apoptosis is often a prerequisite to establish a host-pathogen relationship. some pathogens kill macrophages by inducing apoptosis and thus overcome the microbicidal arsenal of the phagocyte. apoptotic macrophages, on the other hand, can elicit an inflammation by secretion of proinflammatory cytokines. shigella flexneri, the aetiological agent of bacillary dysenter ... | 1997 | 9571693 |
| identification of epitope and surface-exposed domains of shigella flexneri invasion plasmid antigen d (ipad). | transport and surface expression of the invasion plasmid antigens (ipa proteins) is an essential trait in the pathogenicity of shigella spp. in addition to the type iii protein secretion system encoded by the mxi/spa loci on the large virulence plasmid, transport of ipab and ipac into the surrounding medium is modulated by ipad. to characterize the structural topography of ipad, the geysen epitope-mapping system was used to identify epitopes recognized by surface-reactive monoclonal and polyclon ... | 1998 | 9573082 |
| neural wiskott-aldrich syndrome protein is implicated in the actin-based motility of shigella flexneri. | shigella, the causative agent of bacillary dysentery, is capable of directing its own movement in the cytoplasm of infected epithelial cells. the bacterial surface protein virg recruits host components mediating actin polymerization, which is thought to serve as the propulsive force. here, we show that neural wiskott-aldrich syndrome protein (n-wasp), which is a critical target for filopodium formation downstream of cdc42, is required for assembly of the actin tail generated by intracellular s.f ... | 1998 | 9582270 |
| induction of type iii secretion in shigella flexneri is associated with differential control of transcription of genes encoding secreted proteins. | shigella, the etiological agent of human bacillary dysentery, invades the colonic epithelium where it induces an intense inflammatory response. entry of shigella into epithelial cells involves a type iii secretion machinery, encoded by the mxi and spa operons, and the ipaa-d secreted proteins. in this study, we have identified secreted proteins of 46 and 60 kda as the products of vira and ipah9.8, respectively, the latter being a member of the ipah multigene family. inactivation of vira did not ... | 1998 | 9582283 |
| clearance of shigella flexneri infection occurs through a nitric oxide-independent mechanism. | nitric oxide (no) generated by gamma interferon (ifn-gamma) activation of macrophages mediates the killing of many intracellular pathogens. ifn-gamma is essential to innate resistance to shigella flexneri infection. we demonstrate that no is produced following s. flexneri infection both in mice and in activated cells in vitro and that while it is able to kill s. flexneri in a cell-free system, it is not required for clearance of s. flexneri in either infected mice or in activated cells in vitro. | 1998 | 9596784 |
| mechanism of antigenic variation in shigella flexneri bacilli. iv. role of lipopolysaccharides and their components in the sensitivity of shigella flexneri 1b and its lac+ recombinant to killing action of serum. | the effect of lipopolysaccharides (lps) on the normal bovine serum (nbs) bactericidal reactions against mixture of s. flexneri 6713 1b strain and its 3b lac+ recombinant were investigated. the serum killing of s. flexneri strains was inhibited, in different degree, by lps extracted from either organisms. these properties were mainly due to lps molecules; the lipid a fraction showed only low anticomplement activity, the polysaccharide fraction inhibited the killing activity of nbs in very low deg ... | 1997 | 9597093 |
| assessment of invasion frequencies of cultured hep-2 cells by clinical isolates of helicobacter pylori using an acridine orange assay. | recent studies suggest that helicobacter pylori is an invasive enteropathogen. however, the efficiency with which this pathogen invades mammalian cells remains unknown. therefore, this study was designed to investigate the invasion frequencies of hep-2 cells by clinical strains of h pylori. | 1998 | 9602686 |
| the vacb gene required for virulence in shigella flexneri and escherichia coli encodes the exoribonuclease rnase r. | vacb, a gene previously shown to be required for expression of virulence in shigella and enteroinvasive escherichia coli, has been found to encode the 3'-5' exoribonuclease, rnase r. thus, cloning of e. coli vacb led to overexpression of rnase r activity, and partial deletion or interruption of the cloned gene abolished this overexpression. interruption of the chromosomal copy of vacb eliminated endogenous rnase r activity; however, the absence of rnase r by itself had no effect on cell growth. ... | 1998 | 9603904 |
| [multiple antibiotic resistance mediated by r plasmid in shigella flexneri strains isolated in the northeast of brazil]. | in shigella strains were studied the molecular mechanism that mediated the multiply antibiotic-resistance. twenty-six strains of shigella flexneri were utilised in this investigation. these strains were submitted to disk diffusion test, mating experiments and plasmid isolation. in relation to antibiotics resistance standard it was observed that all shigella flexneri strains were resistant to at least, three antibiotics tested. from twenty-six shigella flexneri strains donors submitted to conjuga ... | 1998 | 9612017 |
| [the adaptation of therapeutic standards as a function of antibiotic sensitivity of strains of shigella spp. isolated in rwanda in 1997]. | 1997 | 9612786 | |
| type iii protein secretion systems in bacterial pathogens of animals and plants. | various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. it is becoming increasingly clear that these so-called type iii secretion systems inject (translocate) proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. accordingly, some type iii secretion systems are activat ... | 1998 | 9618447 |
| [mechanism of resistance of shigella flexneri 2a resistant to new quinolone antibiotics]. | a shigella flexneri 2a strain, which did not respond clinically or in laboratory tests to treatment with new quinolone derivatives, was isolated for the first time in japan from a patient admitted for diarrhea to a tokyo hospital. the mechanism of resistance was examined by sequencing the quinolone resistance determining region (qrdr) of the gyra (a quinolone target enzyme) gene and by comparing the active efflux mechanisms of two strains isolated from this patient (before hospitalization and af ... | 1998 | 9621565 |
| delivery of the non-membrane-permeative antibiotic gentamicin into mammalian cells by using shigella flexneri membrane vesicles. | we developed a model to test whether non-membrane-permeative therapeutic agents such as gentamicin could be delivered into mammalian cells by means of bacterial membrane vesicles. many gram-negative bacteria bleb off membrane vesicles (mvs) during normal growth, and the quantity of these vesicles can be increased by brief exposure to gentamicin (j. l. kadurugamuwa and t. j. beveridge, j. bacteriol. 177:3998-4008, 1995), which can be entrapped within the mvs. gentamicin-induced mvs (g-mvs) were i ... | 1998 | 9624497 |
| novel metallo beta-lactamase mediated by a shigella flexneri plasmid. | novel carbapenem-hydrolyzing beta-lactamase (newly named met-1) encoded on a transferable plasmid pms390 from shigella flexneri js19622 was purified. the molecular weight was 28,000 by sds-page and the isoelectric point was higher than 9.3. this beta-lactamase favorably hydrolyzed classical cephalosporins and oxyimino-cephalosporins rather than penicillins and carbapenems, but did not hydrolyze monobactams. the enzymatic activity was inhibited by edta, and the enzyme was found to contain two mol ... | 1998 | 9627953 |
| two highly related regulatory proteins, shigella flexneri virf and enterotoxigenic escherichia coli rns, have common and distinct regulatory properties. | the rns protein of enterotoxigenic escherichia coli (etec) and the virf protein of shigella flexneri are members of the arac family of transcription regulators. rns is required for positive activation of the cs1 fimbrial genes, while virf is a positive regulator of an invasion gene regulon. the amino acid sequences of the proteins are 36% identical, and both proteins activate transcription in response to increases in temperature. here, we show that rns is capable of complementing fully a null mu ... | 1998 | 9627965 |
| revised model for aerobic growth of shigella flexneri to extend the validity of predictions at temperatures between 10 and 19 degrees c. | although shigella is a major foodborne pathogen, its growth in foods has received little attention. growth of s. flexneri 5348 inoculated into commercially available sterile foods (canned broths, meat, fish, uht milk, baby foods) was studied at 10 to 37 degrees c. s. flexneri was enumerated by surface-plating on tryptic soy agar and growth curves were fitted by means of the gompertz equation. observed growth kinetics values and values calculated using a previously developed response surface mode ... | 1998 | 9631334 |
| occurrence and susceptibility to antibiotics of shigella species in stools of hospitalized children with bloody diarrhea in pakistan. | the aim of the present investigation was to study the frequency of shigella spp. in patients with bloody diarrhea in pakistan and the susceptibility of isolated shigella to three antibiotics: ampicillin, cotrimoxazole and nalidixic acid. in addition, the frequency of campylobacter and salmonella was also determined. stool samples (n = 152) were collected from 152 diarrheic children less than six years of age passing blood and mucus in their stools who were admitted to paediatric department of ma ... | 1998 | 9660467 |
| fresh orange juice implicated in an outbreak of shigella flexneri among visitors to a south african game reserve. | 1998 | 9661958 | |
| interactions of the invasive pathogens salmonella typhimurium, listeria monocytogenes, and shigella flexneri with m cells and murine peyer's patches. | invasive enteric bacteria must pass through the intestinal epithelium in order to establish infection. it is becoming clear that a common target for intestinal mucosa penetration is the specialized epithelial cell of peyer's patches, the m cell. in order to gain a better understanding of how bacteria interact with m cells, we have compared the interactions of salmonella typhimurium, listeria monocytogenes, and shigella flexneri with m cells by using a murine ligated-loop model. our results indic ... | 1998 | 9673259 |
| inactivation of dsba, but not dsbc and dsbd, affects the intracellular survival and virulence of shigella flexneri. | in this study, three mutants, dsba::kan, dsbc-kan, and dsbd-kan, of shigella flexneri serotype 5 were constructed and characterized to investigate the role of the periplasmic thiol:disulfide oxidoreductases in pathogenicity. in gentamicin protection assays and the serény test, the dsba mutant showed reduced virulence while the dsbc and dsbd mutants were similar to the wild type. that inactivation of dsba was responsible for the reduced virulence was verified by complementation with the cloned wi ... | 1998 | 9673279 |
| hemolysin-positive enteroaggregative and cell-detaching escherichia coli strains cause oncosis of human monocyte-derived macrophages and apoptosis of murine j774 cells. | infection of human monocyte-derived macrophages (hmdm) and j774 cells (murine macrophage cell line) with several enteroaggregative and cytodetaching escherichia coli (eaggec and cdec, respectively) strains demonstrated that some strains could induce macrophage cell death accompanied by release of lactate dehydrogenase activity and interleukin 1beta (il-1beta) into culture supernatants. the mode of cell death differed in the two types of macrophages. damage to macrophage plasma membrane integrity ... | 1998 | 9673280 |
| overexpression and topology of the shigella flexneri o-antigen polymerase (rfc/wzy). | lipopolysaccharides (lps), particularly the o-antigen component, are one of many virulence determinants necessary for shigella flexneri pathogenesis. o-antigen biosynthesis is determined mostly by genes located in the rfb region of the chromosome. the rfc/wzy gene encodes the o-antigen polymerase, an integral membrane protein, which polymerizes the o-antigen repeat units of the lps. the wild-type rfc/wzy gene has no detectable ribosome-binding site (rbs) and four rare codons in the translation i ... | 1998 | 9680210 |
| "biphasic" fevers often consist of more than two phases. | this paper disproves the common belief that all doses of lipopolysaccharide (lps) that are commonly referred to as biphasic fever inducing (>/=2 microg/kg) cause truly biphasic responses. a catheter was implanted into the right jugular vein of several strains of adult male rats, and the animals were habituated to the experimental conditions. at an ambient temperature of 30.0 degrees c, loosely restrained animals were injected with a 10 microg/kg dose of lps (various preparations), and their colo ... | 1998 | 9688995 |
| antimicrobial resistances among shigella in new zealand. | to determine the prevalence of antimicrobial resistances among recent isolates of shigella in new zealand. | 1998 | 9695753 |
| sepa, the 110 kda protein secreted by shigella flexneri: two-domain structure and proteolytic activity. | shigellosis is characterized by a strong inflammatory response which is induced by bacteria invading the colonic mucosa. characterization of a sepa mutant indicated that sepa, the major protein secreted by shigella flexneri growing in laboratory media, might be involved in invasion and destruction of the host intestinal epithelium. the sequence of the first 500 residues of mature sepa (110 kda) is homologous to that of the n-terminal region of iga1 proteases. to investigate the potential proteol ... | 1998 | 9695914 |
| [interhospital spread of shigella flexneri 2a]. | in this article the results of the study of regularities in the development of outbreak morbidity in shigellosis, caused by s.flexneri 2a, in hospitals are presented. the study was carried out with the use of the method of typing by the plasmid profile. the study showed the continuity of the epidemic process in the foci which appeared at intervals considerably exceeding the incubation period. the fact of the interhospital spread of s.flexneri 2a was established. the strain causing the disease wa ... | 1998 | 9700878 |
| [genotyping of shigella flexneri 2a strains isolated from patients with acute dysentery in st. petersburg]. | polymerase chain reaction with universal primers (up-pcr) was used for the genotyping of 76 s.flexneri 2a cultures isolated from patients with acute dysentery in infectious and psychoneurological hospitals of st. petersburg. 9 types were determined, and each of them included cultures with identical up-pcr patterns. the population of the infective agent was more heterogeneous in psychoneurological hospitals where the change of types was registered in may-september 1995. some of these types were p ... | 1998 | 9700887 |
| incidence & enteropathogenicity of aeromonas spp in children suffering from acute diarrhoea in chennai. | a total of 200 stool samples from children below 10 yr suffering from diarrhoea were screened for enteric pathogens with special interest on aeromonas. aeromonas spp were isolated from 6.5 per cent of the patients, comprising 4 per cent a. hydrophila, 2 per cent a. sobria and 0.5 per cent a. caviae. among the 13 isolates obtained, 10 isolates produced enterotoxin in ligated rabbit ileal loops, and 11 produced cytotoxin in hep 2 cells. many of the aeromonas isolates exhibited resistance to common ... | 1998 | 9701892 |
| study of the relatedness of isolates of shigella flexneri and shigella sonnei obtained in 1986 and 1987 and in 1994 and 1995 from hong kong. | we used pulsed-field gel electrophoresis (pfge) to study the genetic relatedness of 235 isolates of shigella flexneri and shigella sonnei collected in hong kong (97 isolates from 1986 and 1987 and 138 isolates from 1994 and 1995). altogether, 13 gels were run with bacteriophage lambda ladder dna (pharmacia) as an external reference in every sixth lane, standardized reagents and methods, and isolates randomized for species and years. for quantitative illustration of the relationships within a lar ... | 1998 | 9705363 |
| examination of serpulina pilosicoli for attachment and invasion determinants of enterobacteria. | the spirochaete, serpulina pilosicoli, is the agent of intestinal spirochaetosis, a diarrhoeal disease of humans and other species. by mechanisms as yet unknown, large numbers of these spirochaetes intimately attach to the colonic mucosa by one cell end. in some infected individuals, the spirochaetes may invade the lamina propria and adjacent tissues, and they may cause spirochaetaemia. to examine s. pilosicoli for pathogenic determinants homologous with enterobacteria, dna was extracted from si ... | 1998 | 9711840 |
| requirement of the shigella flexneri virulence plasmid in the ability to induce trafficking of neutrophils across polarized monolayers of the intestinal epithelium. | attachment of an array of enteric pathogens to epithelial surfaces is accompanied by recruitment of polymorphonuclear leukocytes (pmn) across the intestinal epithelium. in this report, we examine how shigella-intestinal epithelium interactions evoke the mucosal inflammatory response. we modeled these interactions in vitro by using polarized monolayers of the human intestinal epithelial cell line, t84, isolated human pmns, and shigella flexneri. we show that shigella attachment to t84-cell basola ... | 1998 | 9712773 |
| alteration of hla-b27 peptide presentation after infection of transfected murine l cells by shigella flexneri. | shigella flexneri is a triggering agent for reactive arthritis in hla-b27-susceptible individuals. considering the intracellular multiplication of bacteria, it seems likely that bacterial peptides may be presented by the major histocompatibility complex (mhc) class i pathway. to examine this hypothesis, we infected hla-b*2705- and/or human beta2-microglobulin-transfected murine l-cell lines with m90t, an invasive strain of s. flexneri. bacterial infection induced no detectable modifications in t ... | 1998 | 9712804 |
| construction of a stable attenuated shigella sonnei deltavirg vaccine strain, wrss1, and protective efficacy and immunogenicity in the guinea pig keratoconjunctivitis model. | construction of a stable shigella sonnei vaccine has been complicated by the instability of the virulence phenotype caused by the spontaneous loss of the invasion plasmid. to select a suitable candidate for vaccine construction, 16 s. sonnei strains were screened for stability of the virulence phenotype. a stable strain, s. sonnei mosely, was selected for further work. pdeltavirg2, a deletion derivative of the virg gene in the sacb suicide vector pcvd442, was used to generate an s. sonnei virg d ... | 1998 | 9712824 |
| molecular and cellular mechanisms of invasion of the intestinal barrier by enteric pathogens. the paradigm of shigella. | the pathogenesis of bacillary dysentery can be studied at different levels of integration of the cellular components that constitute the colonic mucosal barrier. we considered the interaction of shigella flexneri in three experimental systems that provide complementary information and a scheme of events occurring in human colorectal mucosa as shigella invasion proceeds. interaction of s. flexneri with individual epithelial cells shows a series of events in which the bacterium, upon contact with ... | 1998 | 9717250 |
| the shigella virulence gene regulatory cascade: a paradigm of bacterial gene control mechanisms. | shigella flexneri is the causative agent of bacillary dysentery and is a facultative intracellular pathogen. its virulence regulon is subject to tight control by several mechanisms involving the products of over 20 genes and an array of environmental signals. the reguion is carried on a plasmid that is prone to instability and to integration into the chromosome, with associated silencing of the virulence genes. closely related regulons are found in other species of shigella and in enteroinvasive ... | 1998 | 9723908 |
| enteroinvasive bacteria directly activate expression of inos and no production in human colon epithelial cells. | in these studies, we investigated whether bacterial infection of human colon epithelial cells is a sufficient stimulus to upregulate epithelial cell expression of inducible nitric oxide synthase (inos) and nitric oxide (no) production. human colon epithelial cells (caco-2 and ht-29) rapidly upregulated inos mrna and protein expression and no production after infection with enteroinvasive escherichia coli, salmonella dublin, or shigella flexneri but not after infection with noninvasive e. coli or ... | 1998 | 9724270 |
| age-related prevalence of shigella and salmonella antibodies and their association with diarrhoeal diseases in peruvian children. | shigella and salmonella antibodies in relation to diarrhoea were studied in a cohort of 413 children between 2 and 27 months of age in peri-urban lima, peru. blood samples were obtained at 2, 3 and 12 months of age. antibody titres against lipopolysaccharide from shigella flexneri serotype y, shigella dysenteriae serotype 1, shigella sonnei, salmonella serogroups ao, bo, do, and shigella ipa and salmonella typhi vi antigens were measured by enzyme immunoassay. igg titres against s. flexneri and ... | 1998 | 9730303 |
| an outbreak of infection with shigella flexneri 1b in south east england. | 1998 | 9737062 | |
| serotype conversion of a shigella flexneri candidate vaccine strain via a novel site-specific chromosome-integration system. | shigella flexneri sfl124 (serotype y) is a promising live oral vaccine candidate, which has been shown to be safe and immunogenic in human volunteers. to change the serotype of this vaccine strain, we inserted a serotype conversion gene cluster into the chromosome of sfl124 by using a bacteriophage-based site-specific integration system. by cloning an integrase gene (int), an attachment site (attp) and a glucosyl transfer gene cluster from bacteriophage sfx into a suicide vector, and subsequentl ... | 1998 | 9741086 |
| identification of two shigella flexneri chromosomal loci involved in intercellular spreading. | the ability of shigella flexneri to multiply within colonic epithelial cells and spread to adjacent cells is essential for production of dysentery. two s. flexneri chromosomal loci that are required for these processes were identified by screening a pool of tnphoa insertion mutants. these mutants were able to invade cultured epithelial cells but could not form wild-type plaques. analysis of the nucleotide sequence indicated that the sites of tnphoa insertion were within two different regions tha ... | 1998 | 9746567 |
| expression of the virulence plasmid-carried apyrase gene (apy) of enteroinvasive escherichia coli and shigella flexneri is under the control of h-ns and the virf and virb regulatory cascade. | the transcription of the virulence plasmid (pinv)-carried invasion genes of shigella flexneri and enteroinvasive escherichia coli (eiec) is induced at 37 degreesc and repressed at 30 degreesc. in this work, we report that the o135: k-:h- eiec strain hn280 and s. flexneri sfzm53, m90t, and 454, of serotypes 4, 5, and 2a, respectively, produce apyrase (atp-diphosphohydrolase), the product of the apy gene. in addition, the s. flexneri strains, but not the eiec strain, produce a nonspecific phosphat ... | 1998 | 9746603 |
| shigella infections among children in andaman--an archipelago of tropical islands in bay of bengal. | shigellosis is common among children in the andaman and nicobar islands. our experience showed two distinct features of shigellosis within a span of 3 years in 1994-6: (i) changing patterns of serotype or subtype specific shigellosis and (ii) emergence of multidrug resistant isolates with changing r-patterns. the rate of isolation was 10.4-27.9% with the rate of isolation of shigella flexneri interchanging with s. dysenteriae alternately. in 1994, s. flexneri superseded s. dysenteriae (48.6% vs. ... | 1998 | 9747754 |
| h-ns regulates dna repair in shigella. | we report a new role for h-ns in shigella spp.: suppression of repair of dna damage after uv irradiation. h-ns-mediated suppression of virulence gene expression is thermoregulated in shigella, being functional at 30 degrees c and nonfunctional at 37 to 40 degrees c. we find that h-ns-mediated suppression of dna repair after uv irradiation is also thermoregulated. thus, shigella flexneri m90t, incubated at 37 or 40 degrees c postirradiation, shows up to 30-fold higher survival than when incubated ... | 1998 | 9748466 |
| molecular characterization of the virulence gene virg of ptiku 12. | the virulence (vir) genes of agrobacterium tumefaciens ku12, a korean strain, were not induced by acetosyringone and the strain showed weak tumor forming ability and broad plant host ranges. we identified complete nucleotide sequence of virg of ptiku12, an octopine ti plasmid of this strain. when it was compared with those of other ti plasmids, ptiku12 virg contained an open reading frame (orf) of 726 nucleotides which showed much lower homology (about 77%) than those (above 98%) already known a ... | 1998 | 9749525 |
| acid-sensitive enteric pathogens are protected from killing under extremely acidic conditions of ph 2.5 when they are inoculated onto certain solid food sources. | gastric acidity is recognized as the first line of defense against food-borne pathogens, and the ability of pathogens to resist this ph corresponds to their oral infective dose (id). naturally occurring and genetically engineered acid-sensitive enteric pathogens were examined for their ability to survive under acidic conditions of ph 2.5 for 2 h at 37 degreesc when inoculated onto ground beef. each of the strains displayed significantly high survival rates under these normally lethal conditions. ... | 1998 | 9758814 |
| [ampicillin resistance mediated by the r plasmid in strains of shigella flexneri]. | forty shigella flexneri strains isolated from children attended to at the children's hospital of camagüey during an outbreak of acute diarrheal disease were studied; the minimal inhibitory concentration of ampicillin was determined. 33 strains (82.5%) were resistant to higher concentrations: 8 to 16 micrograms/ml, and 7 were susceptible to 4 micrograms/ml concentrations. resistance plasmid (r) extraction was carried out in all the isolated strains and a common plasmid was found this plasmid was ... | 1994 | 9768253 |
| [invasion of escherichia coli a2 induces reorganization of actin microfilaments in hep-2 cells]. | bacteria of spontaneously isolated non-pathogenic strain e. coli a2 have been previously shown to produce a new proteinase, referred to as protease ecp 32, which specifically cleaves actin (khaitlina et al., 1988; matveyev et al., 1996). similar proteinase activity was found in revertants of shigella flexneri l-forms. in this work immunofluorescence and electron microscopy were used to address a question of whether e. coli a2 can invade epithelial cells similarly as it has been demonstrated for ... | 1998 | 9778735 |
| shigella and enteroinvasive escherichia coli strains are derived from distinct ancestral strains of e. coli. | the differentiation between shigella subspecies, and the phylogenetic position of shigella clones within escherichia coli clones was determined by analysis of restriction fragment length polymorphisms of rdna (ribotyping). seventy-five shigella strains belonging to the four subspecies and 13 enteroinvasive e. coli (eiec) strains were compared with the 72 e. coli strains of the ecor collection, which have been classified into four phylogenetic groups (a, b1, b2 and d). seventeen shigella dysenter ... | 1998 | 9782516 |
| [a case of bacillary dysentery caused by new quinolone-resistant shigella flexneri 2a]. | a 73-year-old male was admitted to our hospital because of detection of shigella flexneri 2a from his stool. antimicrobial treatment with levofloxacin (lvfx) was started, but could not eliminate the organism in the stool. in the examination of drug susceptibility, this strain was highly resistant to all new quinolones. the minimal inhibitory concentration of norfloxacin, ofloxacin and ciprofloxacin to this strain was 12.5 micrograms/ml, 6.25 micrograms/ml and 6.25 micrograms/ml, respectively. th ... | 1998 | 9796193 |
| antimicrobial susceptibilities and beta-lactamase production of shigella isolates in crete, greece, during the period 1991-1995. | the susceptibility to 11 antibiotics was determined for 52 strains of shigella isolated from patients with diarrheal disease in crete, greece, during the period 1991-1995. forty-six percent of the isolates were resistant to ampicillin, 48% to tetracycline, 44.2% to chloramphenicol, and 28.8% to cotrimoxazole. shigella flexneri was more resistant than s. sonnei to ampicillin (82 vs 4.3%), to tetracycline (82 vs 8.7%) and to cotrimoxazole (42.8 vs 13%). overall, 82% of all s. flexneri isolates wer ... | 1998 | 9808414 |
| western blotting analysis of heat shock proteins of rickettsiales and other eubacteria. | heat shock proteins (hsp) of four rickettsia species, three bartonella species, two ehrlichia species, orientia tsutsugamushi and seventeen other eubacterial species were characterized by the enhanced chemiluminescence western blotting (wb) technique with antibodies raised against recombinant hsp from escherichia coli and purified groes from r. typhi. although e. coli dnak and groel have epitopes that are highly conserved among the homologous proteins found in rickettsia, ehrlichia, o. tsutsugam ... | 1998 | 9809424 |
| protein deficiency in a colony of western lowland gorillas (gorilla g. gorilla) | a syndrome of alopecia and weight loss in a colony of 10 western lowland gorillas (gorilla gorilla gorilla) in gabon during a 3-yr period was apparently due to a dietary protein deficiency, with nine individuals affected to some extent. the most severely afflicted was a 4-yr-old female who eventually died as a result of acute gastroenteritis caused by shigella flexneri. clinical signs included chronic alopecia, hair discoloration, failure to thrive, and weight loss, and their severity was direct ... | 1998 | 9809596 |
| drug resistance of shigella strains isolated in ankara, turkey, 1993-1996. | 289 shigella strains were isolated from children at the paediatrics department of ankara university. 75% of the isolates were s. sonnei and 24.8% were s. flexneri. each strain was tested for resistance to 9 antimicrobial agents. 79% of the isolates were resistant to streptomycin (s), 56% to tetracycline (t), 55.7% to trimethoprim-sulfamethoxazole (sxt), 27.7% to ampicillin (am) and 19.7% to chloramphenicol (c). none of the isolates was resistant to ciprofloxacin, nalidixic acid, cephalothin, amp ... | 1998 | 9817513 |
| interferon alpha inhibits a src-mediated pathway necessary for shigella-induced cytoskeletal rearrangements in epithelial cells. | shigella flexneri, the causative agent of bacillary dysentery, has the ability to enter nonphagocytic cells. the interferon (ifn) family of cytokines was found to inhibit shigella invasion of cultured epithelial cells. we show here that ifn-alpha inhibits a src-dependent signaling cascade triggered by shigella that leads to the reorganization of the host cell cytoskeleton. immunofluorescence studies showed that ifn-alpha inhibits shigella-induced actin polymerization required for bacterial entry ... | 1998 | 9817757 |
| shigella infection as observed in the experimentally inoculated domestic pig, sus scrofa domestica. | the domestic pig, sus scrofa domestica, was investigated as a potential animal model for shigellosis. we examined the effects of pig age, pig breed and antibiotic pretreatment upon shigella infection. shigella dysenteriae, and shigella flexneri (both virulent and avirulent strains) were utilized. our results indicated that young (4-week-old), conventionally re ared, domestic pigs were routinely, but briefly, colonized (average=3.5+/-2.5 days) following oral or gavage administration ofs. flexneri ... | 1998 | 9817822 |
| structural features, physiological roles, and biotechnological applications of the membrane proteases of the ompt bacterial endopeptidase family: a micro-review. | the proteins of the ompt family represent a new class of integral membrane peptidases showing no sequence homology with other known classes of proteases. the prototype of the family, the escherichia coli k-12 protein ompt (or omptin), is an outer membrane endopeptidase with unusual specificity: it cleaves the peptide bond between two basic amino acids. a second distinct characteristic of ompt is its ability to function even under extreme denaturing conditions (e.g. high concentration of urea). t ... | 1998 | 9829254 |
| thermoregulation of shigella and escherichia coli eiec pathogenicity. a temperature-dependent structural transition of dna modulates accessibility of virf promoter to transcriptional repressor h-ns. | the expression of plasmid-borne virf of shigella encoding a transcriptional regulator of the arac family, is required to initiate a cascade of events resulting in activation of several operons encoding invasion functions. h-ns, one of the main nucleoid-associated proteins, controls the temperature-dependent expression of the virulence genes by repressing the in vivo transcription of virf only below a critical temperature (approximately 32 degrees c). this temperature-dependent transcriptional re ... | 1998 | 9843508 |
| index of suspicion. case 2. diagnosis: bacillary dysentery and campylobacter infections. | 1998 | 9849074 | |
| multiresistant shigella species isolated from pediatric patients with acute diarrheal disease. | a total of 57 strains of shigella (36 s sonnei, 21 s flexneri), isolated from children with acute diarrheal disease who presented for treatment at the andes university hospital, merida, venezuela, from june 1993 to june 1995, were tested for their susceptibility to trimethoprim, sulfamethoxazole, ampicillin, cefamandole, ceftriaxone, streptomycin, fleroxacin, and nalidixic acid, by the agar dilution method. twenty-seven strains (75%) of s sonnei and eight strains of s flexneri (38.1%) isolates s ... | 1998 | 9856691 |
| peripheral blood cd14(+) cells from healthy subjects carry a circular conformation of latent cytomegalovirus genome. | the majority of the human population harbors latent cytomegalovirus. although cd14(+) peripheral blood mononuclear cells have been implicated as sites of latency, the conformation of the latent viral genome in these cells is unknown. in this study, the conformation of viral genomic dna was assessed in cd14(+) cells from healthy virus seropositive carriers using an electrophoretic separation on native agarose gels in combination with polymerase chain reaction detection. here we show that the vira ... | 1999 | 9864186 |
| establishment of unipolar localization of icsa in shigella flexneri 2a is not dependent on virulence plasmid determinants. | unipolar localization of icsa on the surface of shigella flexneri is required for efficient formation of actin tails and protrusions in infected eucaryotic cells. lipopolysaccharide (lps) mutations have been demonstrated to affect either the establishment or the maintenance of icsa in a unipolar location, although the mechanism is unknown. in order to analyze the contribution of virulence plasmid determinants on the unipolar localization of icsa, we examined the localization of icsa expressed fr ... | 1999 | 9864236 |
| psa causes oncogenic suppression of agrobacterium by inhibiting vire2 protein export. | when coresident with the ti (tumor-inducing) plasmid, the 21-kda product of the osa gene of the plasmid psa can suppress crown gall tumorigenesis incited by agrobacterium tumefaciens. neither t-dna processing nor vir (virulence) gene induction is affected by the presence of osa in the bacterium. we used arabidopsis thaliana root segments and tobacco leaf discs to demonstrate that osa inhibits a. tumefaciens from transforming these plants to the stable phenotypes of tumorigenesis, kanamycin resis ... | 1999 | 9864329 |
| shigella and the fluorinated quinolones. | between july 1996 to june 1997 a total of 531 stool samples from cases of acute diarrhoea, dysentry, colitis admitted to kasturba medical college hospital, manipal were investigated. shigella were isolated from 29 samples (5.46%). out of them, shigella flexneri were 16 (55.17%), shigella boydii 8 (27.58%), shigella dysentriae 3 (10.34%) and shigella sonnei 2 (6.89%). five strains of shigella flexneri and one strain of shigella dysentriae were found to show resistance to nalidixic acid and the ne ... | 1998 | 9866907 |
| novel combination of mutations in the dna gyrase and topoisomerase iv genes in laboratory-grown fluoroquinolone-resistant shigella flexneri mutants. | 1998 | 9867794 | |
| short-chain fatty acids improve clinical, pathologic, and microbiologic features of experimental shigellosis. | because of the metabolic and antibacterial actions of short-chain fatty acids (scfa), their roles in modifying the clinicopathologic features of shigellosis were evaluated in a rabbit model of shigellosis. acute colitis was induced in adult rabbits by intracolonic administration of shigella flexneri 2a. after 24 h, rabbits were given 6-h colonic infusions of scfa (acetate, propionate, n-butyrate; 60:30:40 mm) or scfa-free solution (control); groups of rabbits were killed in batches of 2 or 3 ani ... | 1999 | 9878023 |
| the trithorax group gene osa encodes an arid-domain protein that genetically interacts with the brahma chromatin-remodeling factor to regulate transcription. | the trithorax group gene brahma (brm) encodes the atpase subunit of a chromatin-remodeling complex involved in homeotic gene regulation. we report here that brm interacts with another trithorax group gene, osa, to regulate the expression of the antennapedia p2 promoter. regulation of antennapedia by brm and osa proteins requires sequences 5' to the p2 promoter. loss of maternal osa function causes severe segmentation defects, indicating that the function of osa is not limited to homeotic gene re ... | 1999 | 9895321 |
| characterization of the avian pathogenic escherichia coli hemagglutinin tsh, a member of the immunoglobulin a protease-type family of autotransporters. | we reported earlier that a single gene, tsh, isolated from a strain of avian pathogenic escherichia coli (apec) was sufficient to confer on e. coli k-12 a hemagglutinin-positive phenotype and that the deduced sequence of the tsh protein shared homology to the serine-type immunoglobulin a (iga) proteases of neisseria gonorrhoeae and haemophilus influenzae. in this report we show that e. coli k-12 containing the recombinant tsh gene produced two proteins, a 106-kda extracellular protein and a 33-k ... | 1999 | 9916089 |
| strategy for cross-protection among shigella flexneri serotypes. | based upon the lipopolysaccharide (lps) structure and antigenicity of shigella group b, a strategy for broad cross-protection against 14 shigella flexneri serotypes was designed. this strategy involves the use of two s. flexneri serotypes (2a and 3a), which together bear the all of the major antigenic group factors of this group. the novel attenuated strains used in these studies were s. flexneri 2a strain cvd 1207 (deltaguab-a deltavirg deltaset1 deltasen) and s. flexneri 3a strain cvd 1211 (de ... | 1999 | 9916090 |
| protein-protein interactions in the assembly of shigella flexneri invasion plasmid antigens ipab and ipac into protein complexes. | shigella flexneri is a facultative intracellular bacterial pathogen that invades human colonic epithelial cells by a process called pathogen-induced phagocytosis. pathogen entry requires three virulence plasmid-encoded proteins called invasion plasmid antigens (ipa) b, c and d which are secreted upon bacterial contact with a host cell. following their secretion, ipab and ipac are found within a complex of proteins that may also contain ipaa and ipad. previous work has shown that exogenously adde ... | 1998 | 9920383 |
| functional analysis of a rickettsial ompa homology domain of shigella flexneri icsa. | shigella flexneri is a gram-negative bacterium that causes diarrhea and dysentery by invasion and spread through the colonic epithelium. bacteria spread by assembling actin and other cytoskeletal proteins of the host into "actin tails" at the bacterial pole; actin tail assembly provides the force required to move bacteria through the cell cytoplasm and into adjacent cells. the 120-kda s. flexneri outer membrane protein icsa is essential for actin assembly. icsa is anchored in the outer membrane ... | 1999 | 9922250 |
| effect of wzx (rfbx) mutations on a-band and b-band lipopolysaccharide biosynthesis in pseudomonas aeruginosa o5. | the wbp cluster of pseudomonas aeruginosa o5 encodes a number of proteins involved in biosynthesis of the heteropolymeric and wzy-dependent b-band o antigen, including wzy, the o-antigen polymerase, and wzz, the regulator of o-antigen chain length. a gene (formerly wbpf), contiguous with wzy in the wbp cluster, is predicted to encode a highly hydrophobic protein with multiple membrane-spanning domains. this secondary structure is consistent with that of wzx (rfbx), the putative o-antigen unit tr ... | 1999 | 9922263 |