Use of a novel approach, termed island probing, identifies the Shigella flexneri she pathogenicity island which encodes a homolog of the immunoglobulin A protease-like family of proteins

The she gene of Shigella flexneri 2a, which also harbors the internal enterotoxin genes set1A and set1B (F. R. Noriega, GenBank accession no. U35656, 1995) encodes a homolog of the virulence-related immunoglobulin A (IgA) protease-like family of secreted proteins, Tsh, EspC, SepA, and Hap, from an avian pathogenic Escherichia coli, an enteropathogenic E. coli, S. flexneri 5, and Haemophilus influenzae, respectively. To investigate the possibility that this locus was carried on a larger deletable element, the S. flexneri 2a YSH6000T she gene was insertionally disrupted by allelic exchange using a Tn10-derived tetAR(B) cassette. Then, to detect loss of the she locus, the tetracycline-resistant derivative was plated onto fusaric acid medium to select for tetracycline-sensitive revertants, which were observed to arise at a frequency of 10(-5) to 10(-6). PCR and pulsed-field gel electrophoresis analysis confirmed loss of the she::tetAR(B) locus in six independent tetracycline-sensitive isolates. Sample sequencing over a 25-kb region flanking she identified four insertion sequence-like elements, the group II intron-like sequence Sf.IntA, and the 3' end of a second IgA protease-like homolog, sigA, lying 3.6 kb downstream and in an orientation inverted with respect to she. The deletion was mapped to chromosomal NotI fragment A and determined to have a size of 51 kb. Hybridization with flanking probes confirmed that at least 17.7 kb of the 51-kb deletable element was unique to the seven she+ strains investigated, supporting the conclusion that she lay within a large pathogenicity island. The method described in this study, termed island probing, provides a useful tool to further the study of pathogenicity islands in general. Importantly, this approach could also be of value in constructing safer live attenuated bacterial vaccines.

The sacB gene cannot be used as a counter-selectable marker in Pasteurella multocida

The use of the Bacillus subtilis sacB gene as a counter-selectable marker was assessed in serogroup A and B strains of Pasteurella multocida. Expression ofsacB failed to render any of the strains sensitive to sucrose, indicating that the sacB gene can not be used as a positive selection system in P. multocida.

Interstitial lung disease in recent onset rheumatoid arthritis

Interstitial lung disease (ILD) is associated with rheumatoid arthritis (RA); however, the prevalence and natural history are undefined. Our aim was to determine the prevalence of ILD associated with RA using a number of sensitive techniques in patients with joint disease of less than 2-yr duration. Patients who met ARA criteria for RA were recruited from community-based and hospital rheumatologists and assessed using the following measures: clinical, lung physiology, radiology (chest X-ray, high resolution CT [HRCT]), bronchoalveolar lavage (BAL) and 99mTc-DTPA nuclear scan. Thirty-six patients (25 female and 11 male) of joint disease duration of (mean +/- SD) 13.2 +/- 8.6 mo were studied. Abnormalities consistent with ILD were found in one or more investigations in 21 of 36 (58%), which were in lung physiology in 22%, CXR in 6%, HRCT in 33%, BAL in 52%, and 99mTc-DTPA nuclear scan in 15%. Based on the results, they were categorized as having clinically significant ILD (Group 1), abnormalities compatible with ILD, but no clinically significant ILD (Group 2) and no abnormalities compatible with ILD (Group 3). Five of 36 (14%) were in Group 1, 16 of 36 (44%) in Group 2, and 15 of 36 (42%) in Group 3. The only risk factor for the presence of abnormalities compatible with ILD was male gender (p < 0.04, Student's t test). In conclusion, changes consistent with ILD in early RA are frequent. The significance of these changes is being determined in a longitudinal study.

A seven item scale for the assessment of disabilities after child and adolescent injuries

OBJECTIVES

To develop a scale to assess physical disabilities after child or adolescent injuries.

SETTING

The three main hospitals of Jerusalem.

METHODS

Telephone interviews pertaining to the injury's effect on the functioning of children 4-17 years old (n = 281) were carried out six months after an injury. Disabilities were recalled by the parents for the period immediately after the injury (short term) and at the time of interview (long term). Of 25 questions derived from the International Classification of Impairments, Disabilities and Handicaps, seven were selected: limitations in walking, running, getting up/lying down, moving in bed, going to the toilet, bathing/keeping personal hygiene, and dressing. Construct validity was tested using the usual, sport, school, and leisure time activities as the gold standard.

RESULTS

The prevalence of short term disabilities ranged from 23.8% to 37.7% and of long term disabilities from 0.4% to 11.8%. Cronbach's alpha was 0.91 for the short term scale and over 0.90 for the different categories of the sociodemographic variables. It decreased to 0.66 for the long term scale. Sensitivity of the short term scale ranged from 77% to 89%, but was lower for the long term scale. Specificity varied from 72% to 84% and increased to 88% to 90%, six months after the injury.

CONCLUSIONS

This scale could be used to study disability after injury among children and adolescents in different cultures. It is a simple method that does not require expert personnel and has relatively high validity and internal reliability.

Macrophages infected with cytopathic bovine viral diarrhea virus release a factor(s) capable of priming uninfected macrophages for activation-induced apoptosis

Bovine bone marrow-derived macrophages infected with the cytopathic biotype of bovine viral diarrhea virus released an antiviral activity into the supernatant which was tentatively characterized as type I interferon because of its physicochemical properties. Such supernatants primed both infected and uninfected macrophages for decreased nitric oxide production and apoptosis in response to lipopolysaccharide. This finding strongly suggests a role of this pathway in the pathogenesis of mucosal disease, a lethal form of infection with cytopathic bovine viral diarrhea virus in which the principal lesions are located in the oral cavity and the gastrointestinal tract, which are known to contain a high concentration of endotoxin.

Identification and characterization of the dTDP-rhamnose biosynthesis and transfer genes of the lipopolysaccharide-related rfb locus in Leptospira interrogans serovar Copenhageni

Immunity to leptospirosis is principally humorally mediated and involves opsonization of leptospires for phagocytosis by macrophages and neutrophils. The only protective antigen identified to date is the leptospiral lipopolysaccharide (LPS), which biochemically resembles typical gram-negative LPS but has greatly reduced endotoxic activity. Little is known about the structure of leptospiral LPS. A 2.1-kb EcoRI fragment from the chromosome of serovar Copenhageni was cloned in pUC18 in Escherichia coli, after which flanking regions were cloned from a genomic library constructed in bacteriophage lambda GEM12. Sequence analysis identified four open reading frames which showed similarity to the rfbC, rfbD, rfbB, and rfbA genes, transcribed in that order, which encode the four enzymes involved in the biosynthesis of dTDP-rhamnose for the assembly of LPS in Salmonella enterica, E. coli, and Shigella flexneri. An additional open reading frame downstream of the rfbCDBA locus showed similarity with the rhamnosyltransferase genes of Shigella and Yersinia enterocolitica but not Salmonella. Comparison of deduced amino acid sequences showed up to 85% similarity of the leptospiral proteins with those of other gram-negative bacteria. Polyacrylamide gel electrophoresis of recombinant clones identified the putative RfbCDBA proteins, while reverse transcriptase-mediated PCR analysis indicated that the rfbCDBA gene cluster was expressed in Leptospira. Moreover, it could restore normal LPS phenotype to a defined rfbB::Tn5 mutant of S. flexneri which was deficient in all four genes, thereby confirming the functional identification of a part of the leptospiral rfb locus.

Reported health concerns of Israeli high school students--differences by age and sex

Health concerns of high school students in the 10th grade and again in the 12th grade were studied. The students filled out an anonymous questionnaire that included a list of 73 concerns. At both ages their main concerns were reportedly related to school. Concerns relating to army service ranked high particularly in the 12th grade, among both sexes. Concerns relating to sexual relations were frequent among boys at both ages, whereas concerns about mood and loneliness were more frequent among girls. Reports on physical concerns were frequently related to height among the younger boys and weight and diet among girls of both ages. Concerns were grouped into 6 domains. In each of them, except for sexuality, girls had more concerns. A significant decline in the number of concerns was noted from the first to the second survey, indicating a partial resolution of the issues central to adolescent development. Knowledge about concerns of adolescents may help health care providers in counseling and health education program planning.

Cross protective immunity conferred by a marker-free aroA mutant of Pasteurella multocida

The aroA gene from Pasteurella multocida serotype A:1 (X-73) was cloned by complementation of the Escherichia coli aroA mutant AB2829 with a DNA library constructed in pUC18. The cloned aroA gene was inactivated by deletion of a 300 bp internal sequence and reintroduced by homologous recombination into the chromosome of X-73 and P-1059 (serotype A:3) using a Pasteurella-E. coli shuttle vector pPBA1100. By subjecting the transformed cells to repeated subculturing in the presence of antibiotic selection coupled with auxotrophic enrichment, marker-free aroA mutants of X-73 and of P-1059 were isolated and designated PMP1 and PMP3, respectively. PMP1 and PMP3 were highly attenuated and capable of conferring complete protection against subsequent lethal challenge infection in a mouse model. Moreover, PMP3-immunized mice were protected against heterologous challenge infection with serotype A:1 or A:4.

Identification of a chromosomal Shigella flexneri multi-antibiotic resistance locus which shares sequence and organizational similarity with the resistance region of the plasmid NR1

The ampicillin resistance gene from Shigella flexneri 2a strain YSH6000 was cloned and shown by Southern hybridization analysis to be closely linked to the previously cloned streptomycin, chloramphenicol, and tetracycline resistance determinants, which are borne on a chromosomally integrated 99-kb element. Analysis of this chromosomal multi-antibiotic resistance locus revealed that it had a high level of sequence and organizational similarity to an equivalent region of the Shigella R-plasmid, NR1. However, the chromosomal locus exhibited several differences, including the presence of two stretches of sequence derived from IS elements, the precise insertion of a beta-lactamase encoding oxal cassette into the Tn21-borne integron In2, a possible 17.5-kb deletion, and the loss or inactivation of the mercury resistance determinant. Based on these data, it is proposed that the chromosomal locus arose following integration of an NR1-like plasmid.

Identification, purification, and characterization of the type 4 fimbriae of Pasteurella multocida

The presence of fimbriae on Pasteurella multocida has been reported, but there have been no prior studies aimed at conclusively characterizing these structures. We now report on the identification and characterization of type 4 fimbriae on serogroup A, B, and D strains of P. multocida. Under microaerophilic conditions P. multocida showed an increased expression of the fimbriae, which were observed to form bundles. Fimbriae purified by high-performance reverse-phase liquid chromatography constituted a single 18-kDa subunit, the first 21 amino acids of which shared very high similarity with the N-terminal amino acid sequence of other type 4 fimbrial subunits. Antiserum against the P. multocida 18-kDa protein immunostained the type 4 fimbrial subunit of Moraxella bovis and Dichelobacter nodosus. Based on these observations we conclude that P. multocida possesses type 4 fimbriae and have designated the P. multocida fimbrial subunit PtfA.

Insertional and deletional RNA editing in trypanosome mitochondria

The mitochondrial mRNAs of trypanosomes are often post-transcriptionally modified by an RNA processing event, termed RNA editing, which results in the insertion or deletion of uridylate (U) residues in mRNAs. RNA editing is necessary for the formation of complete coding sequences for several essential mitochondrial proteins. The number and site of U addition and deletion is directed by small guide RNAs (gRNAs). Recent studies indicate that the mechanism of RNA editing in trypanosomes involves a series of enzymatic steps. We show that the initial step in this enzymatic cascade requires the formation of a binary RNA complex between the gRNA and its cognate pre-mRNA. Depletion of specific gRNAs inhibits cleavage of the pre-mRNA by an editing site specific endoribonuclease. Addition of synthetic gRNAs reverses this inhibition. All of the activities needed for RNA editing in vitro are present within a 19S ribonucleo-protein complex (RNP) composed of gRNAs, the editing site specific endonuclease, an RNA ligase, a terminal uridylate transferase (TUTase) and approximately 15 other unidentified proteins. We have recently identified and cloned the gene for a 45kDa protein, the RNA Editing Associated Protein-1 (REAP-1), which is a component of trypanosome editing complexes. REAP-1 co-purifies with RNA ligase and TUTase activities and is part of a > 700 kDa RNP containing gRNAs. Antibodies against REAP-1 inhibit in vitro RNA editing reactions confirming its role in RNA editing.

Inducible nitric oxide synthase of macrophages. Present knowledge and evidence for species-specific regulation

An important mechanism by which macrophages (M phi) halt the growth of and eliminate a broad array of intracellular pathogens is the production of nitric oxide (NO). NO generation is catalyzed by inducible nitric oxide synthase (iNOS) converting arginine into citrulline and NO. In murine M phi, iNOS activity is regulated largely at the transcriptional level. LPS and IFN-gamma induce iNOS, IL-4 and TGF-beta down-regulate LPS or IFN-gamma induced iNOS. In human M phi, iNOS cannot be induced by conventional activating regimes in vitro. We studied iNOS induction in ruminant monocytes and M phi from various sources (bone marrow, alveolar lavage, peripheral blood) and found that there is a species-specific and differentiation stage-dependent pattern of iNOS regulation in vitro. Notably, cattle M phi and monocytes respond to distinct signals by iNOS expression. Goat monocytes and M phi resemble human, pig and rabbit M phi in that upon treatment with conventional activating stimuli, they express less iNOS than unstimulated murine or bovine M phi and fail to generate detectable amounts of nitrite and nitrate.

Evolutionary perspective on a composite Shigella flexneri 2a virulence plasmid-borne locus comprising three distinct genetic elements

Nucleotide sequence analysis of a Shigella flexneri 2a virulence plasmid-borne locus revealed that it comprised three distinct genetic elements: a stretch of colicin 1a/1b-linked sequence, a truncated IS911 element, and a third element containing two ORFs that shared a high level of similarity to a Salmonella-specific chromosomal sequence. Examination of other known IS911-like sequences showed that these sequences also were frequently associated with other accessory elements and appeared to be prone to partial deletion events. Analysis of the data led to a model of the evolution of this unusual composite locus.

Induction of nitric oxide synthase in bovine mononuclear phagocytes is differentiation stage-dependent

Bovine monocytes and monocyte-derived macrophages (MDM) activated by various means were assessed for induction of inducible nitric oxide synthase (iNOS), using the Griess assay, Northern blotting and reverse transcription/polymerase chain reaction (RT-PCR). Interferon-gamma (IFN-gamma) induced little, if any, iNOS expression and NO production in MDM, although these cells responded to IFN-gamma in other regards. In contrasts, MDM produced copious amounts of NO when stimulated with LPS or Salmonella dublin, and this was paralleled by high steady state levels of iNOS mRNA. Heat-killed Listeria monocytogenes induced more iNOS mRNA and nitrite than IFN-gamma, but much less than L. mono-cytogenes and IFN-gamma combined. Monocytes differed from M phi with respect to iNOS induction and nitrite production in several regards: (i) LPS and S. dublin induced only low levels of iNOS mRNA and nitrite in monocytes, although cells responded to these stimuli in various other ways: (ii) IFN-gamma alone induced in monocytes iNOS mRNA generation and NO formation, although to a low and variable degree; (iii) upon maximal stimulation (e.g. by L. monocytogenes and IFN-gamma combined), monocytes produced much less nitrite than MDM, and mRNA levels were lower. Regulation of macrophage iNOS varies considerably between species. We provide the first evidence in any species that the steady state levels of iNOS mRNA and NO generation in monocytes and macrophages activated by various means depend on the stage of mononuclear phagocyte differentiation.

Cloning, sequencing, expression, and protective capacity of the oma87 gene encoding the Pasteurella multocida 87-kilodalton outer membrane antigen

Membrane proteins of Pasteurella multocida have been shown previously to elicit protective immunity. We have identified an 87-kDa outer membrane antigen, Oma87, which is present in all 16 serotypes of P. multocida. The gene encoding this protein was cloned and sequenced and found to have significant similarity to the D15 protective surface antigen of Haemophilus influenzae. Oma87 was localized to the outer membrane of the cell, and proteinase K treatment suggested that the protein is surface exposed. Native and recombinant Oma87 were strongly immunostained by convalescent-phase antiserum, indicating that the protein is expressed in vivo. Specific Oma87 antiserum protected mice against homologous, lethal P. multocida challenge. These results suggest that Oma87 is a protective outer membrane antigen of P. multocida.

A spontaneous 99-kb chromosomal deletion results in multi-antibiotic susceptibility and an attenuation of contact haemolysis in Shigella flexneri 2a

A Tn5-generated mutant (strain S2430) of Shigella flexneri 2a (strain YSH6000) exhibited attenuated virulence and, in addition to the Tn5 insertion in the SalI K fragment of its virulence plasmid, had a 99-kb deletion within its chromosome. Unlike its wild-type parent, strain S2430 was susceptible to ampicillin, streptomycin, tetracycline and chloramphenicol. An independent multi-antibiotic susceptible variant of strain YSH6000 had a similar deletion. Southern blot analysis of pulsed field electrophoresis gels enabled the sizing of this deletion and its mapping to a region of the chromosome on NotI fragment D bounded by the S. flexneri homologues of ompA and pyrC. Hybridisation experiments with a probe specific to the multi-antibiotic resistance region indicated that this large deletion was responsible for antibiotic susceptibility. Both strain S2430 and a derivative of the antibiotic-susceptible variant, with a Tn5 insertion in its SalI K fragment, exhibited an equal reduction in contact haemolysis compared with the Tn5-bearing derivative of strain YSH6000. However, strain S2430 alone clearly displayed delayed plaque forming ability in LLC-MK2 monolayers, suggesting that the two examples of this deletion may not be identical.

Time trends of child development in a Jerusalem community

The study of the Development Quotient (DQ-according to the Brunet-Lezine test) of two-year-olds living in a geographically defined area in Western Jerusalem was carried out for the birth cohorts of 1971 to 1989 (n = 4314). An 'Early Stimulation' programme was implemented from 1975 through the Mother and Child Health Clinic. The stimulation programme provided mothers with skills to enhance the development of their children through social interaction, play and verbal stimulation from birth to two years of age. The mean DQ at 2 years old increased significantly from 104.6 (SD = 9.8) for the 1972 cohort to 108.9 (SD = 9.1) for those born in 1989. Coordination and posture subscores followed the trends of the total DQ while the trends in language development were less marked. There is indication that children whose mothers had 9-11 years of schooling benefited more than other children. Better achievement on the developmental test as expressed in the mean DQ was probably related to changing socio-demographic characteristics of the population, and the implementation of the 'Early Stimulation' programme. The widening gap of the DQ after an initial decrease among children whose mothers had < or = 8 years of schooling and those in higher educational groups during the 80s may have been caused by the fact that the latter are a very disadvantaged group of families compared with the rest of the population.

Differential regulation of inducible nitric oxide synthase production in bovine and caprine macrophages

Inducible nitric oxide synthase (iNOS) regulation in human and murine macrophages in vitro differs considerably. In this study, expression of macrophage iNOS in ruminants was addressed. Nitric oxide (NO) output by cattle and goat macrophages was as different as that by human and mouse macrophages. Bovine macrophages activated by heated Salmonella dublin or lipopolysaccharide (LPS) expressed high levels of iNOS mRNA, protein, and enzyme activity. Analogously cultured caprine macrophages did not respond to these and other activators by NO generation and iNOS expression. The lack of response was not due to general unresponsiveness to stimuli. Caprine iNOS mRNA was induced by stimulation of caprine macrophages with LPS, as shown by reverse transcription polymerase chain reaction. The level of mRNA expression in activated goat macrophages was lower than in resting bovine macrophages. A caprine 372-bp iNOS mRNA fragment that was sequenced closely resembled the bovine counterpart. This points to species-specific iNOS gene regulation.

Bilateral vertebral artery tortuosity with concomitant vertebral erosion: CT and MRA findings

Focal vertebral artery tortuosity has been periodically reported as a rare cause of cervical vertebral body and foraminal erosion. Almost all reported cases are unilateral. A case of bilateral vertebral artery tortuosity is described with computed tomography and magnetic resonance angiography findings included.

Immunity and vaccine development in Pasteurella multocida infections

The role of LPS in immunity was studied using monoclonal antibodies (MAbs) and active immunisation experiments. A panel of six MAbs produced against Pasteurella multocida serotype B:2 reacted with the LPS of serotypes B:2 and B:5, but not with other serotypes. The MAbs could opsonise P. multocida for phagocytosis by mouse macrophages, but were not bactericidal in the presence of complement. They conferred only partial passive protection in mice. Similar results showing only partial protection were obtained when purified LPS was used to actively immunise mice prior to challenge, suggesting that LPS plays a partial role in immunity to infection. The aroA gene from P. multocida serotypes A:1 and A:3 was cloned and inactivated by insertion of a kanamycin resistance gene. The mutated gene was re-introduced onto the chromosome by allelic exchange. The resultant aroA mutants were highly attenuated in a mouse model system, with a 6-log decrease in ID50. Virulence could be restored by complementation with a functional aroA gene. Mice immunised with two doses of the live mutants were protected against lethal challenge with the homologous parental strain, but not against the heterologous strain. P. multocida A:1 and A:3 expressed unique proteins when grown in iron-restricted medium. Moreover, the outer membrane (OM) fractions of these cells contained novel proteins of 75 kDa, 85 kDa and 94 kDa molecular mass. Mice were immunised with OM fractions prepared from serotype A:3 grown in iron-restricted (OM Fe-) or iron-replete (OM Fe+) media. When low challenge doses were used, both immunogens protected mice against serotype A:3, but only the OM Fe- fraction protected mice against heterologous challenge with serotype A:1. When higher challenge doses were used, only partial protection was observed.

Preparation of antisera to recombinant, soluble N-acetylglucosaminyltransferase V and its visualization in situ

N-Acetylglucosaminyltransferase V (GlcNAc-T V) is a glycosyltransferase which transfers N-acetylglucosamine in beta(1,6) linkage to the alpha(1,6)-linked mannose residue of Asn-linked oligosaccharides. This enzyme is characterized by several unusual properties: GlcNAc-T V is the largest lumenal Golgi glycosyltransferase described thus far, and its multiple mRNA transcripts range from 4.5 to about 9.5 kb; GlcNAc-T V mRNA and activity are regulated by the src tyrosine kinase signalling pathway; in brain tissue, large levels of GlcNAc-T V mRNA are present, but only relatively low levels of catalytic activity can be detected; a lectin-resistant cell line, Lec4A, expresses active GlcNAc-T V which is mislocalized intracellularly. In addition, the cell surface oligosaccharide products of this enzyme have been hypothesized to regulate intercellular adhesion. In order to devise specific inhibitors of this enzyme it is necessary to understand its physical structure and how structural changes can influence its activity and localization. We have expressed milligram amounts of a soluble form of recombinant rat GlcNAc-T V, purified it from CHO cell-conditioned media, and used it to prepare specific antisera. This antisera binds selectively to GlcNAc-T V and has been used to visualize B-16 mouse melanoma cell GlcNAc-T V on immunoblots after SDS-PAGE. When the antisera was used in immunofluorescence microscopy experiments on permeabilized B-16 and baby hamster kidney cells, intense, specific staining was observed in intracellular structures which appear to correspond to the Golgi apparatus.

Interferon-alpha primes macrophages for lipopolysaccharide-induced apoptosis

Apoptosis plays an important role in generating and maintaining an effective immune system. Many pathogens can perturb the homeostasis of the immune system by either inducing or suppressing cell death of immune cells. Using bovine macrophages as a model, we found that interferon-alpha, one of the host's responses to viral infection, can prime macrophages for activation-induced apoptosis. Exposure of bovine bone-marrow-derived macrophages to interferon-alpha and subsequent activation with lipopolysaccharide led to a strong downregulation of the macrophages' nitric oxide production when compared to lipopolysaccharide stimulation alone. We could show that this was due to induction of apoptosis after activation of the cells. Herpesvirus-induced type I interferon also primed bovine macrophages for lipopolysaccharide-induced apoptosis. Our studies describe how in a novel pathway an antiviral immune response could contribute to pathological sequelae of viral diseases.