Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 23
Filtrar
1.
Hematol Oncol ; 30(3): 137-42, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22105737

RESUMO

Hepatitis C virus (HCV) infection is associated with some B-cell non-Hodgkin lymphoma (B cell-NHLs). Patients with HCV infection frequently show co-infections with GB virus C (GBV-C, formerly known as hepatitis G virus), and some studies have suggested a higher incidence of GBV-C infection in patients with B cell-NHLs. The aim of this study was to prospectively evaluate the association between HCV and/or GBV-C infection and B cell-NHLs in different geographic areas. One hundred thirty-seven lymphoma cases and 125 non-lymphoma matched controls were enrolled in an international case-control study conducted in Switzerland (Bellinzona), Spain (Barcelona) and England (Southampton) on samples collected from 2001 to 2002. In Bellinzona (41 cases and 81 controls), the overall prevalence of HCV was 3.3% (4.9% in NHLs), and the overall prevalence of GBV-C was 24% (22% in NHLs). In Barcelona (46 cases and 44 controls), the prevalence of HCV was 10% (8.7% in NHLs) and the prevalence of GBV-C 20% (13% in NHLs). There was no statistically significant difference in the frequency of both infections between patients with NHL and controls. In Southampton, 50 NHL cases were analysed, none of them was found to be HCV-positive; therefore, no control group was analysed and GBV-C analysis was not performed, too. Both in Bellinzona and in Barcelona, the seropositivity rate was significantly lower for HCV than for GBV-C, suggesting that their transmission can be independent. The incidence of HCV was significantly higher in Barcelona than that in Bellinzona. This study confirmed the existence of marked geographic differences in the prevalence of HCV in NHL but cannot provide any significant evidence for an association between HCV and/or GBV-C and B-cell NHLs.


Assuntos
Infecções por Flaviviridae/epidemiologia , Vírus GB C/isolamento & purificação , Hepatite C/epidemiologia , Hepatite Viral Humana/epidemiologia , Linfoma de Células B/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Antivirais/sangue , Estudos de Casos e Controles , Comorbidade , Feminino , Infecções por Flaviviridae/virologia , Vírus GB C/imunologia , Anticorpos Anti-Hepatite C/sangue , Hepatite Viral Humana/virologia , Humanos , Leucemia Linfocítica Crônica de Células B/epidemiologia , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Prevalência , Estudos Prospectivos , Estudos Soroepidemiológicos , Espanha/epidemiologia , Suíça/epidemiologia , Proteínas do Envelope Viral/imunologia , Macroglobulinemia de Waldenstrom/epidemiologia , Adulto Jovem
2.
FEMS Immunol Med Microbiol ; 53(3): 351-8, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18557937

RESUMO

Bacteria exchange genetic material by horizontal gene transfer (HGT). To evaluate the impact of HGT on Escherichia coli genome plasticity, 19 commensal strains collected from the intestinal floras of humans and animals were analyzed by microarrays. Strains were hybridized against an oligoarray containing 2700 E. coli K12 chromosomal genes. A core (genes shared among compared genomes) and a flexible gene pool (genes unique for each genome) have been identified. Analysis of hybridization signals evidenced 1015 divergent genes among the 19 strains and each strain showed a specific genomic variability pattern. Four hundred and fifty-eight genes were characterized by higher rates of interstrain variation and were considered hyperdivergent. These genes are not randomly distributed onto the chromosome but are clustered in precise regions. Hyperdivergent genes belong to the flexible gene pool and show a specific GC content, differing from that of the chromosome, indicating acquisition by HGT. Among these genes, those involved in defense mechanisms and cell motility as well as intracellular trafficking and secretion were far more represented than others. The observed genome plasticity contributes to the maintenance of genetic diversity and may therefore be a source of evolutionary adaptation and survival.


Assuntos
DNA Bacteriano/genética , Escherichia coli/genética , Transferência Genética Horizontal , Análise em Microsséries , Animais , Composição de Bases , Cromossomos Bacterianos , Escherichia coli/isolamento & purificação , Escherichia coli/fisiologia , Genes Bacterianos , Humanos , Família Multigênica , Polimorfismo Genético , Sintenia
3.
Eur J Pharm Biopharm ; 69(3): 908-22, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18362065

RESUMO

This paper deals with the formulation of targeted liposome against Helicobacter pylori. We describe the characterization of liposomes loaded with antimicrobial agents (ampicillin and metronidazole) and the quantification of the interactions between such formulations and bacteria. If the encapsulation rate of ampicillin seems not strongly affected by the change of phospholipidic composition, the encapsulation of metronidazole drastically decreased in epikuron 170 liposomes compared to DPPC ones. Furthermore, as observed with X-ray diffraction measurements, the presence of metronidazole results in the disorganisation of the phospholipid bilayers. Concerning the liposome-bacteria interactions, it has been observed that the incorporation of fucosyled glycolipids in the vesicle membrane leads to liposomes that are able to interact with the bacteria either in their spiral or in their coccoid forms. Since coccoid forms are occasionally found in vivo, their recognition by the liposomes we have formulated seems promising in the fight against Helicobacter pylori.


Assuntos
Glicolipídeos/química , Helicobacter pylori/efeitos dos fármacos , Lipossomos/química , Fenômenos Químicos , Química Farmacêutica , Físico-Química , Cromatografia Líquida de Alta Pressão , Composição de Medicamentos , Eletroquímica , Excipientes , Microscopia de Fluorescência , Tamanho da Partícula , Fosfolipídeos/química , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Difração de Raios X
4.
FEMS Immunol Med Microbiol ; 50(1): 126-32, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17456180

RESUMO

One hundred and twenty clinical and commensal Escherichia coli strains isolated in Switzerland from humans and from companion and farm animals were analysed for the prevalence of integrons of classes 1, 2, and 3 and for the characterization of their gene cassettes. The relationships between integron carriage and host category, and between integron carriage and phylogenetic E. coli lineage were also analysed. Integrons were detected in 48 (40%) of the isolates and were thus widely disseminated in the human and animal E. coli strains considered. Moreover, the association between integron carriage and certain animal categories (farm animals) suggests that animals that are raised for economic purposes might be exposed to a major antibiotic pressure. Finally, our data confirm that E. coli commensal strains represent a significant source of antibiotic-resistant determinants.


Assuntos
Doenças dos Animais/microbiologia , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Escherichia coli/genética , Integrons/genética , Animais , Sequência de Bases , Gatos , Bovinos , Cães , Escherichia coli/isolamento & purificação , Humanos , Dados de Sequência Molecular , Filogenia , Aves Domésticas , Regiões Promotoras Genéticas/genética , Suínos
5.
Ann Agric Environ Med ; 13(1): 65-70, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16841874

RESUMO

We have designed and performed a new PCR method based on the 18S rRNA in order to individuate the presence and the identity of Babesia parasites. Out of 1159 Ixodes ricinus (Acari: Ixodidae) ticks collected in four areas of Switzerland, nine were found to contain Babesia DNA. Sequencing of the short amplicon obtained (411-452 bp) allowed the identification of three human pathogenic species: Babesia microti, B. divergens, for the first time in Switzerland, Babesia sp. EU1. We also report coinfections with B. sp. EU1-Borrelia burgdorferi sensu stricto and Babesia sp. EU1-B. afzelii.


Assuntos
Vetores Aracnídeos/parasitologia , Babesia/isolamento & purificação , Ixodes/parasitologia , Reação em Cadeia da Polimerase/métodos , Animais , Babesia/classificação , Babesia/patogenicidade , Babesia microti/isolamento & purificação , Babesia microti/patogenicidade , Babesiose/transmissão , Sequência de Bases , DNA de Protozoário/química , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 18S/química , Especificidade da Espécie , Suíça/epidemiologia
6.
Ann N Y Acad Sci ; 1044: 236-43, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15958717

RESUMO

Although many biologic principles are conserved in mice and humans, species-specific differences exist, for example, in susceptibility and response to pathogens, that often do not allow direct implementation of findings in experimental mice to humans. Research in humans, however, for ethical and practical reasons, is largely restricted to in vitro assays that lack components and the complexity of a living organism. To nevertheless study the human hematopoietic and immune system in vivo, xenotransplantation assays have been developed that substitute human components to small animals. Here, we summarize our recent findings that transplantation of human cord blood CD34(+) cells to newborn Rag2(-/-)gamma(c)(-/-) mice leads to de novo development of major functional components of the human adaptive immune system. These human adaptive immune system Rag2(-/-)gamma(c)(-/-) (huAIS-RG) mice can now be used as a technically straightforward preclinical model to evaluate in vivo human adaptive immune system development as well as immune responses, for example, to vaccines or live infectious pathogens.


Assuntos
Cistatinas/fisiologia , Sistema Imunitário/fisiologia , Animais , Antígenos CD34/imunologia , Transplante de Células , Cistatina C , Cistatinas/deficiência , Cistatinas/genética , Proteínas de Ligação a DNA , Sangue Fetal/citologia , Humanos , Recém-Nascido , Linfócitos/citologia , Linfócitos/imunologia , Camundongos , Camundongos Mutantes , Proteínas Nucleares , Transplante Heterólogo
7.
Infect Genet Evol ; 2(2): 111-20, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12797987

RESUMO

Ticks of the Rhipicephalus sanguineus species complex may be vector of various pathogens including Rickettsia conorii (the etiological agent of the Mediterranean spotted fever) and Coxiella burnetii (cause of the Query (Q) fever). R. sanguineus ticks have been imported in several parts of central and northern Europe, especially in environments such as kennels and houses providing the appropriate microclimatic conditions and the blood source necessary for their survival. Since 1940 these ticks have occasionally been recorded in Switzerland. In Ticino (the southern part of Switzerland), they have been reported since 1980 and their probable establishment in this area has been suggested in the '90s. By means of PCR and direct sequencing, we tested the identity of these ticks (using 12S rDNA gene) and the occurrence of Rickettsia spp. (using 16S rDNA, gltA and OmpA genes) as well as Coxiella sp. (using 16S rDNA). The results indicated that in Ticino, two different tick species coexist, i.e. R. sanguineus sensu stricto and Rhipicephalus turanicus. A few individuals of R. sanguineus sensu stricto are infected with Rickettsia massiliae/Bar29, which are strains of unknown pathogenicity. Coxiella sp., an endosymbiont of Rhipicephalus ticks, has also been identified in both tick species. Due to climatic changes towards global warming, imported tick species may therefore adapt to new area and might be considered as epidemiological markers for a number of infectious agents transmitted by them.


Assuntos
Coxiella/genética , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Rickettsia/epidemiologia , Rickettsia/genética , Carrapatos/microbiologia , Animais , DNA Ribossômico , Cães/parasitologia , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Suíça , Carrapatos/classificação , Carrapatos/genética
8.
FEMS Microbiol Lett ; 238(1): 115-23, 2004 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-15336411

RESUMO

A total of 874 Ixodes ricinus ticks were collected in Switzerland to investigate the genetic diversity of the Borrelia population. We integrated to the RT-PCR method the DNA sequence analysis of a 162-bp fragment of the recA gene. Five genospecies were detected: Borrelia afzelii, Borrelia burgdorferi s.s., Borrelia garinii, Borrelia valaisiana, and Borrelia lusitaniae. A heterogeneous distribution was observed within the B. burgdorferi s.l. genospecies. The most prevalent and diverse genospecies found in Switzerland was Borrelia afzelii, which might suggest a rapid evolution of this genospecies.


Assuntos
Grupo Borrelia Burgdorferi/classificação , Grupo Borrelia Burgdorferi/genética , Ixodes/microbiologia , Recombinases Rec A/genética , Animais , Grupo Borrelia Burgdorferi/isolamento & purificação , Gatos , Bovinos , DNA Bacteriano/química , DNA Bacteriano/isolamento & purificação , Cães , Variação Genética , Cabras , Humanos , Larva/microbiologia , Epidemiologia Molecular , Dados de Sequência Molecular , Ninfa/microbiologia , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Homologia de Sequência , Suíça
9.
J Med Microbiol ; 51(2): 123-130, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11863263

RESUMO

The sequences of part of the glutamine synthetase-encoding gene (glnA) and of the RecA-encoding gene (recA) were determined and aligned for 45 Bacteroides fragilis isolates from different clinical and geographical origin. The patterns of sequence divergence of glnA and recA were very similar. The sequences of a 303-bp fraction of recA showed 45 nucleotide substitutions, 40 of which allowed the separation of B. fragilis into two major divisions, which were not found when the deduced amino acid sequences were considered. The 687-bp sequences analysed for the glnA gene showed 112 nucleotide substitutions, 96 of which separated the population into the same two divisions as those described for recA. In this case, the deduced amino acid sequences showed this subdivision as well: three of the six observed amino acid substitutions were division-specific. Within the two divisions, both genes presented a high degree of sequence conservation. Each B. fragilis division was associated with the presence of a different antibiotic resistance gene: cepA encoding a serine-beta-lactamase (division I) and cfiA encoding a metallo-beta-lactamase (division II). No particular clusters associated with geographical or clinical origin, or with the production of an enterotoxin were observed. Sequencing of the cfiA gene allowed identification of two different alleles in division II. However, no association of these different cfiA alleles with the expression of imipenem resistance was observed. In conclusion, the phylogenetic patterns observed by sequencing recA and glnA are in agreement with those obtained previously by MLEE (multilocus enzyme electrophoresis). Thus, it appears that the evolution of recA and glnA genes is similar to that of the whole chromosome of B. fragilis. Horizontal gene transfer between divisions I and II seems to be low, at best. However, the results of the present study could not clarify definitively whether divisions I and II should be considered as two different B. fragilis genospecies.


Assuntos
Proteínas de Bactérias , Bacteroides fragilis/classificação , Farmacorresistência Bacteriana/genética , Glutamato-Amônia Ligase/genética , Recombinases Rec A/genética , beta-Lactamases/genética , Bacteroides fragilis/efeitos dos fármacos , Bacteroides fragilis/genética , Sequência de Bases , Variação Genética , Genótipo , Dados de Sequência Molecular , Filogenia
13.
Antimicrob Agents Chemother ; 52(4): 1366-73, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18195063

RESUMO

Due mainly to the extensive use of antibiotics, the spread of multiresistant bacterial strains is one of the most worrying threats to public health. One strategy that can be used to overcome potential shortcomings might be the inactivation of these microorganisms by 5-aminolevulinic acid (5-ALA) or 5-ALA derivative-mediated photodynamic therapy (PDT). 5-ALA has no photoactive properties, but when it is given exogenously, it acts as a precursor of photosensitive porphyrins predominantly in tissues or organisms that are characterized by a high metabolic turnover, such as tumors, macrophages, and bacteria. However, the weak ability of 5-ALA to cross biological barriers has led to the introduction of more lipophilic derivatives, such as methyl aminolevulinate or hexyl aminolevulinate, which display improved capacities to reach the cytoplasm. Starting from the hypothesis that more lipophilic compounds carrying only a permanent positive charge under physiological conditions may more easily cross the bacterial multilayer barrier, we have tested the efficacies of some 5-ALA n-alkyl esters for the inactivation of bacteria. For this purpose, different bacterial strains were incubated with 5-ALA or its corresponding esters of different lipophilicities. Then, the bacteria were irradiated with light and the numbers of CFU post-PDT were counted and compared to those for the controls, which were kept in the dark. Furthermore, the total amount of accumulated porphyrins was quantified by high-pressure liquid chromatography analysis. In our studies, analysis of the bacterial extracts revealed the presence of all the porphyrins involved in heme biosynthesis, from uroporphyrin to protoporphyin IX. The efficacy of bacterial inactivation was a function of the total amount of porphyrins produced, independently of their nature. The 5-ALA methyl and butyl esters were the most effective compounds with respect to the photodynamic inactivation of bacteria. We observed significant differences in terms of the optimal drug concentration, bactericidal activities, and porphyrin production.


Assuntos
Ácido Aminolevulínico/análogos & derivados , Ácido Aminolevulínico/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia , Ácido Aminolevulínico/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Escherichia coli K12/efeitos dos fármacos , Escherichia coli K12/crescimento & desenvolvimento , Ésteres/química , Ésteres/farmacologia , Bactérias Gram-Negativas/crescimento & desenvolvimento , Bactérias Gram-Positivas/crescimento & desenvolvimento , Resistência a Meticilina , Fármacos Fotossensibilizantes/química , Porfirinas/metabolismo , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
14.
AIDS ; 22(4): 469-79, 2008 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-18301059

RESUMO

BACKGROUND: Although combination antiretroviral therapy (cART) dramatically reduces rates of AIDS and death, a minority of patients experience clinical disease progression during treatment. OBJECTIVE: To investigate whether detection of CXCR4(X4)-specific strains or quantification of X4-specific HIV-1 load predict clinical outcome. METHODS: From the Swiss HIV Cohort Study, 96 participants who initiated cART yet subsequently progressed to AIDS or death were compared with 84 contemporaneous, treated nonprogressors. A sensitive heteroduplex tracking assay was developed to quantify plasma X4 and CCR5 variants and resolve HIV-1 load into coreceptor-specific components. Measurements were analyzed as cofactors of progression in multivariable Cox models adjusted for concurrent CD4 cell count and total viral load, applying inverse probability weights to adjust for sampling bias. RESULTS: Patients with X4 variants at baseline displayed reduced CD4 cell responses compared with those without X4 strains (40 versus 82 cells/microl; P = 0.012). The adjusted multivariable hazard ratio (HR) for clinical progression was 4.8 [95% confidence interval (CI) 2.3-10.0] for those demonstrating X4 strains at baseline. The X4-specific HIV-1 load was a similarly independent predictor, with HR values of 3.7 (95% CI, 1.2-11.3) and 5.9 (95% CI, 2.2-15.0) for baseline loads of 2.2-4.3 and > 4.3 log10 copies/ml, respectively, compared with < 2.2 log10 copies/ml. CONCLUSIONS: HIV-1 coreceptor usage and X4-specific viral loads strongly predicted disease progression during cART, independent of and in addition to CD4 cell count or total viral load. Detection and quantification of X4 strains promise to be clinically useful biomarkers to guide patient management and study HIV-1 pathogenesis.


Assuntos
Terapia Antirretroviral de Alta Atividade , Infecções por HIV/tratamento farmacológico , HIV-1 , Receptores CXCR4/metabolismo , Adulto , Progressão da Doença , Métodos Epidemiológicos , Feminino , Infecções por HIV/imunologia , Humanos , Masculino , Resultado do Tratamento , Carga Viral
15.
Microbiology (Reading) ; 153(Pt 7): 2052-2066, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17600050

RESUMO

Escherichia coli, the common inhabitant of the mammalian intestine, exhibits considerable intraspecies genomic variation, which has been suggested to reflect adaptation to different ecological niches. Also, regulatory trade-offs, e.g. between catabolic versatility and stress protection, are thought to result in significant physiological differences between strains. For these reasons, the relevance of experimental observations made for 'domesticated' E. coli strains with regard to the behaviour of this species in its natural environments is often questioned and doubts are frequently raised on the status of E. coli as a defined species. The variability of important (eco-)physiological functions, such as carbon substrate uptake and breakdown capabilities, as well as stress defence mechanisms, in the genomes of commensal and pathogenic E. coli strains were therefore investigated. Furthermore, (eco-)physiological properties of environmental strains were compared to standard laboratory strain K-12 MG1655. Catabolic, stress protection, and carbon- and energy source transport operons showed a very low intraspecies variability in 57 commensal and pathogenic E. coli. Environmental isolates adapted to glucose-limited growth in a similar way as E. coli MG1655, namely by increasing their catabolic flexibility and by inducing high-affinity substrate uptake systems. The results obtained indicate that significant (eco-)physiological properties are highly conserved in the natural population of E. coli. This questions the proposed dominant role of horizontal gene transfer for niche adaptation.


Assuntos
Proteínas de Escherichia coli , Escherichia coli/fisiologia , Glucose/metabolismo , Microbiologia Ambiental , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Genoma Bacteriano , Dados de Sequência Molecular
16.
J Gen Virol ; 87(Pt 8): 2235-2241, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16847119

RESUMO

Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus, has a positive-strand RNA genome containing a single open reading frame flanked by non-coding regions (NCRs). Ixodes ricinus ticks (n = 307) were collected from vegetation in a natural TBEV focus in Belp, Switzerland. The presence and identity of the virus were determined by nested RT-PCR followed by sequencing of the 5'-terminal region that comprises the 5' NCR and the capsid-encoding region (C). The presence of the western European TBEV subtype (W-TBEV) genome was detected in 14.3 % of the ticks. Nucleotide sequence analysis revealed a high variability of 55.5 %. In particular, four DNA fragments (CS 'A', CS 'B', the folding-stem structure and the start codon) showed substantial heterogeneity, which has the potential of compromising replication, translation and packaging of the viral genome. This variability may reflect a viral strategy to select the fittest RNA molecule to produce a viral infection in the different vertebrate hosts that may be encountered by the ticks. It may also indicate a possible ancient introduction of TBEV to the Belp site. In addition, it may contribute to explaining the annual low incidence of tick-borne encephalitis in the natural focus of Belp, despite the high prevalence of TBEV genomes in ticks.


Assuntos
Vírus da Encefalite Transmitidos por Carrapatos/classificação , Vírus da Encefalite Transmitidos por Carrapatos/genética , Variação Genética , Ixodes/virologia , Regiões 5' não Traduzidas/genética , Animais , Sequência de Bases , Proteínas do Capsídeo/genética , Vírus da Encefalite Transmitidos por Carrapatos/isolamento & purificação , Dados de Sequência Molecular , Filogenia , Mutação Puntual , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Suíça
17.
Microbiology (Reading) ; 146 ( Pt 5): 1241-1254, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-10832652

RESUMO

Ninety-three Bacteroides fragilis strains of different origin were analysed by multilocus enzyme electrophoresis (MLEE). Fourteen of the 15 genetic loci analysed were polymorphic, whilst nucleoside phosphorylase was monomorphic. There was a mean of six alleles per locus and a mean genetic diversity of 0.393. Cluster analysis identified 90 electrophoretic types (ETs) separated into two major phylogenetic divisions at a genetic distance of 0.70. Division I consisted of 81 ETs carrying the endogenous class A beta-lactamase gene cepA, whereas division II comprised 9 ETs carrying the class B beta-lactamase gene cfiA, but not cepA. The presence of these two genes was assessed by PCR and the expression of the cfiA gene was investigated by determining the level of resistance to the antibiotic imipenem. MLEE showed a smaller genetic distance among the genotypes of the imipenem-resistant than among the imipenem-susceptible strains. No other particular cluster was observed. The enterotoxin gene (bft) was detected by PCR: DNA sequencing of the products obtained showed that the different bft alleles (bft-1, bft-2 and bft-3) were scattered randomly troughout the phylogenetic tree. No association between distinct clones and clinical manifestations (sepsis, abscesses, diarrhoea), geographical origin or host origin (human or animal) could be found.


Assuntos
Proteínas de Bactérias , Bacteroides fragilis/genética , beta-Lactamases/genética , Alelos , Animais , Toxinas Bacterianas/genética , Bacteroides fragilis/efeitos dos fármacos , Bacteroides fragilis/enzimologia , Análise por Conglomerados , DNA Bacteriano/análise , DNA Ribossômico/análise , Resistência Microbiana a Medicamentos/genética , Eletroforese em Gel de Amido , Humanos , Imipenem/farmacologia , Metaloendopeptidases/genética , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Pentosiltransferases/análise , Pentosiltransferases/genética , Reação em Cadeia da Polimerase , Polimorfismo Genético , RNA Ribossômico 16S/genética , Tienamicinas/farmacologia
18.
Science ; 304(5667): 104-7, 2004 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-15064419

RESUMO

Because ethical restrictions limit in vivo studies of the human hemato-lymphoid system, substitute human to small animal xenotransplantation models have been employed. Existing models, however, sustain only limited development and maintenance of human lymphoid cells and rarely produce immune responses. Here we show that intrahepatic injection of CD34+ human cord blood cells into conditioned newborn Rag2-/-gammac-/- mice leads to de novo development of B, T, and dendritic cells; formation of structured primary and secondary lymphoid organs; and production of functional immune responses. This provides a valuable model to study development and function of the human adaptive immune system in vivo.


Assuntos
Linfócitos B/imunologia , Células Dendríticas/imunologia , Sangue Fetal/citologia , Transplante de Células-Tronco Hematopoéticas , Sistema Imunitário/fisiologia , Linfócitos T/imunologia , Animais , Animais Recém-Nascidos , Antígenos CD34/análise , Linfócitos B/citologia , Células da Medula Óssea/imunologia , Células Dendríticas/citologia , Células Dendríticas Foliculares/citologia , Células Dendríticas Foliculares/imunologia , Infecções por Vírus Epstein-Barr/imunologia , Rearranjo Gênico do Linfócito T , Humanos , Imunoglobulinas/análise , Recém-Nascido , Linfonodos/citologia , Linfonodos/imunologia , Ativação Linfocitária , Complexo Principal de Histocompatibilidade , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Mutantes , Baço/citologia , Baço/imunologia , Linfócitos T/citologia , Toxoide Tetânico/imunologia , Timo/citologia , Timo/imunologia , Transplante Heterólogo
19.
Microbiology (Reading) ; 147(Pt 6): 1693-1707, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11390701

RESUMO

The population biology of 78 Helicobacter pylori strains (71 from Swiss Italian, 4 from East Asian and 3 from South African patients) was investigated by sequence analysis of four housekeeping genes: atpD, scoB, glnA and recA. The vacA genotype, the presence of cagA and IS605, the iceA allelic type, and the resistance to metronidazole, clarithromycin and amoxycillin were determined. A high percentage of DNA polymorphic sites (19.8% for atpD, 21.3% for scoB, 23.7% for glnA and 20.3% for recA) was found. The phylogenetic trees based on the nucleotide sequences of the four gene fragments showed different topologies and were incongruent. The virulence-associated markers were distributed over the dendrograms and no association was found with phylogenetic clusters or clinical manifestations (chronic gastritis, gastric or duodenal ulcer, MALT lymphoma). Moreover, the H ratios (calculated with the homoplasy test) ranged from 0.742 to 0.799, depending on the gene fragment examined. All these observations suggest that H. pylori exists as a recombinant population. The clustering of the strains according to their geographical origin (USA/Europe, East Asia, South Africa) that has recently been demonstrated elsewhere could only be confirmed for the East Asian vacA s1c strains. In contrast, the South African strains clustered together only in the atpD tree. Presumably, recombination at the different loci has masked the evolutionary relationship among the strains.


Assuntos
Genes Bacterianos , Infecções por Helicobacter/microbiologia , Helicobacter pylori/genética , Biópsia , Elementos de DNA Transponíveis/genética , DNA Bacteriano/análise , Ásia Oriental , Genética Populacional , Genótipo , Helicobacter pylori/patogenicidade , Humanos , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , África do Sul , Estômago/microbiologia , Estômago/cirurgia , Suíça , Virulência
20.
Appl Environ Microbiol ; 69(6): 3203-12, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12788717

RESUMO

Genetic relationships among 62 Vibrio vulnificus strains of different geographical and host origins were analyzed by multilocus enzyme electrophoresis (MLEE), random amplification of polymorphic DNA (RAPD), and sequence analyses of the recA and glnA genes. Out of 15 genetic loci analyzed by MLEE, 11 were polymorphic. Cluster analysis identified 43 distinct electrophoretic types (ETs) separating the V. vulnificus population into two divisions (divisions I and II). One ET (ET 35) included all indole-negative isolates from diseased eels worldwide (biotype 2). A second ET (ET 2) marked all of the strains from Israel isolated from patients who handled St. Peter's fish (biotype 3). RAPD analysis of the 62 V. vulnificus isolates identified 26 different profiles separated into two divisions as well. In general, this subdivision was comparable (but not identical) to that observed by MLEE. Phylogenetic analysis of 543 bp of the recA gene and of 402 bp of the glnA gene also separated the V. vulnificus population into two major divisions in a manner similar to that by MLEE and RAPD. Sequence data again indicated the overall subdivision of the V. vulnificus population into different biotypes. In particular, indole-negative eel-pathogenic isolates (biotype 2) on one hand and the Israeli isolates (biotype 3) on the other tended to cluster together in both gene trees. None of the methods showed an association between distinct clones and human clinical manifestations. Furthermore, except for the Israeli strains, only minor clusters comprising geographically related isolates were observed. In conclusion, all three approaches (MLEE, RAPD, and DNA sequencing) generated comparable but not always equivalent results. The significance of the two divisions (divisions I and II) still remains to be clarified, and a reevaluation of the definition of the biotypes is also needed.


Assuntos
Enguias/microbiologia , Vibrioses/microbiologia , Vibrio vulnificus/classificação , Vibrio vulnificus/genética , Animais , Técnicas de Tipagem Bacteriana , Eletroforese/métodos , Doenças dos Peixes/microbiologia , Variação Genética , Genética Populacional , Glutamato-Amônia Ligase/genética , Humanos , Dados de Sequência Molecular , Filogenia , Técnica de Amplificação ao Acaso de DNA Polimórfico , Recombinases Rec A/genética , Análise de Sequência de DNA , Vibrioses/veterinária , Vibrio vulnificus/patogenicidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA