UMLS:C0348321 - FACTA Search

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Query: UMLS:C0348321 (Haemophilus)
15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The intragenomic heterogeneity of the bacterial intergenic (16S-23S rDNA) spacer region (ISR) was analysed from the following species in which sequences for the complete rRNA operon (rrn) set have been determined (rrn number): Enterococcus faecalis (6) and E. faecium (6), Bacillus subtilis (10), Staphylococcus aureus (9), Vibrio cholerae (4), Haemophilus influenzae (6) and Escherichia coli (7). It was found that some spacer sequence blocks were highly conserved between operons of a genome, whereas the presence of others was variable. When these variations were analysed using the program PLATO and partial likelihood phylogenies determined by DNAml for each operon set, three regions showed significant (Z>3.3) spatial variation [Region I was 78-184 nt long (2.1<Z<49.4), Region II was 10-60 nt long (3.7<Z<23)] and Region III was 6 nt long (3.4<Z>4.4) possibly due to recombination or selection. Within Region I, there was sequence block variation in all operon sets [some operons contained tRNA genes (tRNAala, tRNAile or tRNAglu), whereas others had sequence blocks such as VS2 (S. aureus) or rsl (E. coli)]. Q Analysis of the ISR sequence from E. faecalis and E. faecium showed that there was more interspecies than intraspecies variation (both in DNA sequence and in the presence or absence of blocks). Dot matrix analysis of the sequence blocks in the nine rrn ISRs from S. aureus showed that there was significant homology between VS2 and VS5/VS6. Furthermore, repeat motifs with only A or T were present in higher copy numbers in VS5/VS6 than in VS2. Since these sequence blocks (VS2 and VS5-VS6) are related, intragenic evolution resulting in AT expansion may have occurred between these two regions. A model is proposed that postulates a role for recombination and AT-expansion in intra-genomic ISR variations. This process may represent a general mechanism of concerted evolution for bacterial ISR rearrangements.
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PMID:The role of recombination and mutation in 16S-23S rDNA spacer rearrangements. 1057 Oct

Nontypeable Haemophilus influenzae (NTHI) is a major pathogen of otitis media. One of the outer membrane proteins of NTHI, P6, is an antigen common to all strains and is considered as a candidate for mucosal vaccine. To elucidate the possibility of developing a nasal vaccine against nontypeable Haemophilus influenzae (NTHI) and to investigate mucosal immune responses in the middle ear, mice were immunized intranasally with the P6 outer membrane protein of NTHI, and P6-specific immune responses in the middle ear mucosa were examined. Mice were given with P6 and cholera toxin intranasally as an adjuvant on days 0, 7, and 14 and were killed on day 21. The P6-specific immunoglobulin A (IgA) antibody titer in ear wash was significantly elevated. Mononuclear cells were isolated from middle ear mucosa, and an increase in P6-specific IgA-producing cells was shown with an enzyme-linked immunospot assay. In addition, an increase in memory T cells in middle ear mucosa was detected with flow cytometric analysis after intranasal immunization. Moreover, in vitro stimulation with P6 resulted in proliferation of purified CD4(+) T cells from immunized mice, and these T cells expressed Th2 cytokine mRNA. These results indicate that P6-specific IgA-B-cell immune responses and selected Th2 cytokine expressing Th cells were induced in middle ear mucosa by intranasal immunization. These findings suggest that a nasal vaccine is useful for preventing otitis media with effusion.
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PMID:Induction of specific immunoglobulin A and Th2 immune responses to P6 outer membrane protein of nontypeable Haemophilus influenzae in middle ear mucosa by intranasal immunization. 1072 32

Vast changes are taking place in vaccinology consequent to the introduction of new technologies. Amongst the vaccines included in the Expanded Programme of Immunization (EPI), the pertussis vaccine has been replaced by acellular purified fractions devoid of side-effects. Non-pathogenic but immunogenic mutants of tetanus and diptheria toxins are likely to replace the toxoids. An effective vaccine against hepatitis B prepared by recombinant technology is in large-scale use. Conjugated vaccines against Haemophilus influenzae b, S. pneumococcus and meningococcus are now available, as also vaccines against mumps, rubella and measles. Combination vaccines have been devised to limit the number of injections. Vaccine delivery systems have been developed to deliver multiple doses of the vaccine at a single contact point. A genetically-engineered oral vaccine for typhoid imparts better and longer duration of immunity. Oral vaccines for cholera and other enteric infections are under clinical trials. The nose as a route for immunization is showing promise for mucosal immunity and for anti-inflammatory experimental vaccines against multiple sclerosis and insulin-dependent diabetes mellitus. The range of vaccines has expanded to include pathogens resident in the body such as Helicobacter pylori (duodenal ulcer), S. mutans (dental caries), and human papilloma virus (carcinoma of the cervix). An important progress is the recognition that DNA alone can constitute the vaccines, inducing both humoral and cell-mediated immune responses. A large number of DNA vaccines have been made and shown interesting results in experimental animals. Live recombinant vaccines against rabies and rinderpest have proven to be highly effective for controlling these infections in the field, and those for AIDS are under clinical trial. Potent adjuvants have added to the efficacy of the vaccines. New technologies have emerged to 'humanize' mouse monoclonals by genetic engineering and express these efficiently in plants. These recombinant antibodies are opening out an era of highly specific and safe therapeutic interventions. Human recombinant antibodies would be invaluable for treating patients with terminal tetanus and rabies. Antibodies are already in use for treatment of cancer, rheumatoid arthritis and allergies. An advantage of preformed antibodies directed at a defined target and given in adequate amounts is the certainty of efficacy in every recipient, in contrast to vaccines, where the quality and quantum of immune response varies from individual to individual.
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PMID:The impact of new technologies on vaccines. 1073 30

Common mucosal immune responses were depressed in aged mice that were orally immunized with Haemophilus influenzae type b oligosaccharide conjugated to Diphtheria CRM197 protein (Hib-DT) vaccine using cholera toxin as the mucosal adjuvant. Both common mucosal and systemic humoral immune responses were also depressed in aged mice that were subcutaneously immunized with vaccine formulations containing Hib-DT plus 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). Dietary supplementation of aged mice with either the antioxidant vitamin E, or with known activators of the alpha isoform of the peroxisome proliferator activated receptor (PPAR-alpha) was capable of restoring their mucosal and systemic humoral immune responses to mature adult levels, by both the oral and subcutaneous routes of immunization. These data support a hypothesis that some aspects of immunosenescence are due to dysregulations in cellular functions, and are not due to any irreversible defects in cellular components of the immune system.
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PMID:Enhancement of common mucosal immunity in aged mice following their supplementation with various antioxidants. 1073 95

In this study, the in vitro activity of levofloxacin (LVFX) against 1,020 fresh bacterial clinical isolates was compared with the activities of a range of ofloxacin, ciprofloxacin (CPFX), ampicillin (ABPC), cefaclor, cefpodoxime, methicillin and benzylpenicillin. The clinical isolates except Vibrio cholerae were collected in Japan during 1998 from patients with infectious diseases. MICs were determined using the agar dilution method according to the recommendations by the Japan Society of Chemotherapy. Some isolates of methicillin resistant Staphylococcus aureus (MRSA) and coagulase negative Staphylococcus were resistant to fluoroquinolones, but the MIC50 of LVFX against MRSA was 6.25 micrograms/ml. LVFX was the most active against MRSA among the antibiotics tested. Most of Staphylococcus epidermidis strains were susceptible to the fluoroquinolones. LVFX showed greater activity against all streptococci strains compared with fluoroquinolones tested. In particular, all Streptococcus pneumoniae strains including PRSP were susceptible to LVFX at < or = 1.56 micrograms/ml. Among Enterococcus, ABPC showed superior activity against Enterococcus faecalis but many isolates of Enterococcus species were resistant to ABPC. LVFX was more active against to these Enterococcus species compared with other fluoroquinolones. On the other hand, LVFX and CPFX showed similar activity against isolates of Enterobacteriaceae. CPFX had an MIC50/90 of 0.20, 0.39 microgram/ml and LVFX showed an MIC50/90 of 0.78, 1.56 micrograms/ml against Pseudomonas aeruginosa. LVFX (MIC50/90 0.10, 0.20 microgram/ml) was more active against Acinetobacter species than CPFX (MIC50/90 0.10, 0.39 microgram/ml). Haemophilus influenzae, Branhamella (Moraxella) catarrhalis and V. cholerae were inhibited by low concentration of the fluoroquinolones tested. The MIC90 of LVFX and CPFX were < or = 0.10 microgram/ml against above three species. Some isolates of Neisseria gonorrhoeae and Campylobacter species were moderately resistant to the fluoroquinolones tested but the MIC50 of LVFX and CPFX were < or = 0.39 microgram/ml. Among anaerobes, Propionibacterium acnes was more susceptible than Peptostreptococcus species, and the MIC90 of beta-lactams and fluoroquinolones tested were < or = 0.78 microgram/ml. In conclusion, this study, performed on large number of strains, confirmed an excellent and wide spectrum antibacterial activity of LVFX compared with the fluoroquinolones and beta-lactams tested. And our results suggest that LVFX may be useful in the treatment of various bacterial infections.
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PMID:[In vitro activities of levofloxacin and other antibiotics against fresh clinical isolates]. 1074 92

This study describes an algorithm that finds rho-independent transcription terminators in bacterial genomes and evaluates the accuracy of its predictions. The algorithm identifies terminators by searching for a common mRNA motif: a hairpin structure followed by a short uracil-rich region. For each terminator, an energy-scoring function that reflects hairpin stability, and a tail-scoring function based on the number of U nucleotides and their proximity to the stem, are computed. A confidence value can be assigned to each terminator by analyzing candidate terminators found both within and between genes, and taking into account the energy and tail scores. The confidence is an empirical estimate of the probability that the sequence is a true terminator. The algorithm was used to conduct a comprehensive analysis of 12 bacterial genomes to identify likely candidates for rho-independent transcription terminators. Four of these genomes (Deinococcus radiodurans, Escherichia coli, Haemophilus influenzae and Vibrio cholerae) were found to have large numbers of rho-independent terminators. Among the other genomes, most appear to have no transcription terminators of this type, with the exception of Thermotoga maritima. A set of 131 experimentally determined E. coli terminators was used to evaluate the sensitivity of the method, which ranges from 89 % to 98 %, with corresponding false positive rates of 2 % and 18 %.
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PMID:Prediction of transcription terminators in bacterial genomes. 1092 90

Our approach in predicting gene expression levels relates to codon usage differences among gene classes. In prokaryotic genomes, genes that deviate strongly in codon usage from the average gene but are sufficiently similar in codon usage to ribosomal protein genes, to translation and transcription processing factors, and to chaperone-degradation proteins are predicted highly expressed (PHX). By these criteria, PHX genes in most prokaryotic genomes include those encoding ribosomal proteins, translation and transcription processing factors, and chaperone proteins and genes of principal energy metabolism. In particular, for the fast-growing species Escherichia coli, Vibrio cholerae, Bacillus subtilis, and Haemophilus influenzae, major glycolysis and tricarboxylic acid cycle genes are PHX. In Synechocystis, prime genes of photosynthesis are PHX, and in methanogens, PHX genes include those essential for methanogenesis. Overall, the three protein families-ribosomal proteins, protein synthesis factors, and chaperone complexes-are needed at many stages of the life cycle, and apparently bacteria have evolved codon usage to maintain appropriate growth, stability, and plasticity. New interpretations of the capacity of Deinococcus radiodurans for resistance to high doses of ionizing radiation is based on an excess of PHX chaperone-degradation genes and detoxification genes. Expression levels of selected classes of genes, including those for flagella, electron transport, detoxification, histidine kinases, and others, are analyzed. Flagellar PHX genes are conspicuous among spirochete genomes. PHX genes are positively correlated with strong Shine-Dalgarno signal sequences. Specific regulatory proteins, e.g., two-component sensor proteins, are rarely PHX. Genes involved in pathways for the synthesis of vitamins record low predicted expression levels. Several distinctive PHX genes of the available complete prokaryotic genomes are highlighted. Relationships of PHX genes with stoichiometry, multifunctionality, and operon structures are discussed. Our methodology may be used complementary to experimental expression analysis.
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PMID:Predicted highly expressed genes of diverse prokaryotic genomes. 1096 Jan 11

Over the past decades, the differentiation of bacterial strains for epidemiological purposes had been based on conventional phenotypic characters. More recently, methods studying the directly coded molecules or semantides (nucleic acids or proteins) have allowed, concomitantly with the technical progresses of electrophoresis, the description of stable, discriminant, reproducible markers, which were applicable to large series of isolates. Initially applied to study nosocomial infections in industrialised countries, these methods appear to be particularly suitable for an approach of the epidemiology of endemic bacterial infections in sub-Saharan Africa. The fact that these tools remain costly and technically complicated explains that most of these studies are conducted in the laboratories of industrialized countries. This research reveals the epidemiological complexity of most of these infections. Thus, the epidemiology of trachoma was studied by the analysis of polymorphism of the major outer membrane protein gene of Chlamydia trachomatis in a village of Gambia. A PCR based technique was used to determine the frequency of infection in symptomatic and clinically negative subjects and to specify the prevalence of the genotypes. The epidemiology of plague was studied by the restriction fragment length polymorphism (RFLP) analysis of the ribosomal RNA genes (ribotyping). Distinct ribotypes differentiated the strains of the first two pandemics from the third one. The strains of African origin were particularly heterogeneous, especially in Kenya. This diversity may be explained by the fact that the plague focus is extremely ancient in Central Africa. Bacterial agents of meningitis were also studied. The electrophoretic polymorphism of outer membrane proteins of Haemophilus influenzae of b type was used to specify the epidemiology of meningitis in Gambia. The invasive strains exhibited distinct profiles from non-invasive strains. Different types were evidenced in the west, east and central parts of the country. The antigenic polymorphism of outer membrane proteins of Neisseria meningitidis allowed the differentiation of the strains isolated in Mali according to the period of isolation. Thus, the endemic strains of A serotype were distinguished from those belonging to the same serotype, which were responsible for the 1994 epidemic. Several molecular methods were applied to the typing of Vibrio cholerae strains, particularly those of the seventh pandemic. The enzyme electrophoretic polymorphism (MLEE), a technique based on RFLP analysis of toxin genes, the arbitrarily primed PCR (AP-PCR) and mainly the ribotyping were applied. This last method revealed that in Africa several clones of V. Cholerae El Tor were responsible for the seventh pandemic. Moreover the technique has evidenced the intercontinental spread of a clone of V. Cholerae isolated in 1993 in Calcutta and identified a year later in Guinea-Bissau. Tuberculosis is at present the first opportunistic infection linked to HIV infection in sub-Saharan Africa. Tuberculosis incidence is particularly high and is expected to increase. Several molecular methods, including IS 6110 RFLP analysis, AP-PCR and spoligotyping were used to study the epidemiology of tuberculosis in various countries: South Africa, Tanzania, Zimbabwe, Kenya and Malawi. The aims of this research varied: prevalence of reactivation and of recently acquired infections, routes of contamination, degree of genetic diversity of the organisms isolated in a given geographic area, urban and rural origins of the infections, comparison of isolates from HIV seropositive and HIV seronegative patients. Identical profiles in the strains isolated from several patients could correspond to clusters of infections. However, the identification of epidemiological links in most clusters is hard to obtain. (ABSTRACT TRUNCATED)
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PMID:[Molecular epidemiology of large bacterial endemics in Sub-Saharan Africa]. 1103 62

A Haemophilus influenzae gene encoding a protein with high homology to ArcB receptor protein from Escherichia coli has been cloned. An error in the previously reported sequence of this gene has been found, thus increasing its open reading frame. The cloned gene comprising the entire open reading frame restores oxygen-dependent regulation of succinate dehydrogenase in an ArcB-deficient E. coli strain. Thus, this gene is a functional analog of ArcB from E. coli. By screening partially sequenced bacterial genomes using the BLAST program, proteins with high homology to ArcB protein from E. coli were found in Salmonella typhi, Yersinia pestis, Vibrio cholerae, and Pasteurella multocida. Comparison of these proteins with ArcB protein from E. coli and H. influenzae revealed conserved amino acid regions. Transmembrane helix II was shown to be highly homologous in all the ArcB-type proteins. The involvement of this region in ArcB-mediated oxygen-dependent regulation is suggested.
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PMID:Analysis of HI0220 protein from Haemophilus influenzae, a novel structural and functional analog of ArcB protein from Escherichia coli. 1111 51

The comparative approach is a powerful tool for the analysis of gene regulation in bacterial genomes. It can be applied to the analysis of regulons that have been studied experimentally as well as that of regulons for which no known regulatory sites are available. It is assumed that the set of co-regulated genes and the regulatory signal itself are conserved in related genomes. Here, we use genomic comparisons to study the regulation of transport and utilization systems for sugar acids in gamma purple bacteria Escherichia coli, Salmonella typhi, Klebsiella pneumoniae, Yersinia pestis, Erwinia chrysanthemi, Haemophilus influenzae and Vibrio cholerae. The variability of the operon structure and the location of the operator sites for the main transcription factors are demonstrated. The common metabolic map is combined with known and predicted regulatory interactions. It includes all known and predicted members of the GntR, UxuR/ExuR, KdgR, UidR and IdnR regulons. Moreover, most members of these regulons seem to be under catabolite repression mediated by CRP. The candidate UxuR/ExuR signal is proposed, the KdgR consensus is extended, and new operators for all transcription factors are identified in all studied genomes. Two new members of the KdgR regulon, a hypothetical ATP-dependent transport system OgtABCD and YjgK protein with unknown function, are detected. The former is likely to be the transport system for the products of pectin degradation, oligogalacturonides.
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PMID:Transcriptional regulation of transport and utilization systems for hexuronides, hexuronates and hexonates in gamma purple bacteria. 1111 4

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