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1.
J Bacteriol ; 191(6): 1777-86, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19124575

RESUMO

Contact-dependent growth inhibition (CDI) is a mechanism identified in Escherichia coli by which bacteria expressing two-partner secretion proteins encoded by cdiA and cdiB bind to BamA in the outer membranes of target cells and inhibit their growth. A third gene in the cluster, cdiI, encodes a small protein that is necessary and sufficient to confer immunity to CDI, thereby preventing cells expressing the cdiBA genes from inhibiting their own growth. In this study, the cdiI gene was placed under araBAD promoter control to modulate levels of the immunity protein and thereby induce CDI by removal of arabinose. This CDI autoinhibition system was used for metabolic analyses of a single population of E. coli cells undergoing CDI. Contact-inhibited cells showed altered cell morphology, including the presence of filaments. Notably, CDI was reversible, as evidenced by resumption of cell growth and normal cellular morphology following induction of the CdiI immunity protein. Recovery of cells from CDI also required an energy source. Cells undergoing CDI showed a significant, reversible downregulation of metabolic parameters, including aerobic respiration, proton motive force (Deltap), and steady-state ATP levels. It is unclear whether the decrease in respiration and/or Deltap is directly involved in growth inhibition, but a role for ATP in the CDI mechanism was ruled out using an atp mutant. Consistent with the observed decrease in Deltap, the phage shock response was induced in cells undergoing CDI but not in recovering cells, based on analysis of levels of pspA mRNA.


Assuntos
Inibição de Contato , Regulação para Baixo , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Regulação Bacteriana da Expressão Gênica , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Regiões Promotoras Genéticas
2.
Transfusion ; 29(7): 646-5, 1989 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2672435

RESUMO

Lyme disease (or Lyme borreliosis) is caused by a spirochetal bacteria, Borrelia burgdorferi. Increased recognition of the disease and increased exposure to the vector (ticks) capable of spreading B. burgdorferi from animal hosts have resulted in a rise in the number of cases of Lyme borreliosis reported in the United States. There are three stages of the clinical course of Lyme borreliosis; however, not all those infected will have typical manifestations of each stage, such as the arthritis of the third stage. Routine blood cultures will rarely document bacteremia and serologic testing is not yet reliable. Early treatment can prevent later stages of Lyme borreliosis. There is evidence that transmission of B. burgdorferi by blood transfusion is possible, but, to date, there has been no documentation of transfusion-associated Lyme borreliosis. Thus, no new recommendations for screening donors to identify possible carriers of B. burgdorferi are suggested at this time.


Assuntos
Doença de Lyme/transmissão , Reação Transfusional , Humanos , Fatores de Risco
3.
Transfusion ; 33(5): 362-7, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8488537

RESUMO

Because large numbers of volunteer blood donors may be disqualified for "false-positive" results on tests for antibody to hepatitis B core antigen (anti-HBc), a more specific definition of anti-HBc enzyme immunoassay (EIA)-reactive was evaluated, including only those donor samples that were "strongly" reactive (sample-to-cutoff absorbance ratio, < 0.45). Results using this definition and other anti-HBc test methods were compared to the serologic response (antibody to hepatitis B surface antigen [anti-HBsAg]) to hepatitis B vaccination. Fifty-eight volunteer blood donors who had previously been deferred as donors, because of reactive anti-HBc tests (all other blood screening tests were negative, including those for HBsAg and anti-HBsAg) on two occasions, were vaccinated for hepatitis B. It was assumed that an anamnestic response to vaccine indicated past infection with hepatitis B, while a primary response to vaccine indicated lack of past infection. One (2%) of 43 donors with a historically "weak" anti-HBc (reactive absorbance ratio, > or = 0.45) had an anamnestic response to vaccine, compared to 8 (53%) of 15 with historically "strong" anti-HBc (reactive absorbance ratio, < 0.45) (p < 0.005). Anti-HBc testing using the microparticle EIA method also correlated well with hepatitis B vaccination results. The use of a narrower definition of "reactive" for anti-HBc EIA testing yielded much more specific, but slightly less sensitive, results.


Assuntos
Doadores de Sangue , Anticorpos Anti-Hepatite B/sangue , Antígenos do Núcleo do Vírus da Hepatite B/imunologia , Vacinas contra Hepatite B/sangue , Reações Falso-Positivas , Hepatite B/diagnóstico , Hepatite B/prevenção & controle , Anticorpos Anti-Hepatite B/imunologia , Vacinas contra Hepatite B/imunologia , Vacinas contra Hepatite B/uso terapêutico , Humanos , Técnicas Imunoenzimáticas , Memória Imunológica , Fatores de Tempo , Vacinação
4.
Blood ; 82(3): 1000-5, 1993 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-7687886

RESUMO

When hepatitis C virus antibody (anti-HCV) enzyme immunoassay (EIA1) testing became available in 1990, we tested samples from previously transfused blood units, traced the recipients of reactive units, and evaluated the recipients for HCV infection during the 12 months after transfusion. Ten of 42 recipients of EIA1-reactive blood were anti-HCV reactive on follow-up by EIA1 and 12 were reactive by a second-generation assay (EIA2). Reverse transcriptase-polymerase chain reaction (RT-PCR) detected HCV RNA in 5 seronegative recipients. In all, 17 of 42 recipients (40%) of EIA1-reactive blood had evidence of HCV infection. In comparison, 54 surgery patients, who received either no transfusion or autologous EIA1-nonreactive blood, remained EIA1 nonreactive and RT-PCR negative for 1 year; 1 patient (1.8%) became EIA2 reactive (P < or = .01). Of the recipients of anti-HVC reactive blood transfusions (reactive by both EIA1 and a supplemental 4-antigen strip immunoblot assay [RIBA2]), 14 (93%) of the recipients had evidence of HCV infection compared with only 3 of 27 recipients (11%) of EIA1-reactive, RIBA2-nonreactive blood (P < or = .01). Thus, blood components reactive for anti-HCV EIA1 may have transmitted HCV up to 40% of the time, but blood components found reactive by both EIA1 and RIBA2 may transmit HCV with a frequency of greater than 90%.


Assuntos
Anticorpos Anti-Hepatite/análise , Hepatite C/transmissão , Reação Transfusional , Adulto , Idoso , Doadores de Sangue , Feminino , Hepacivirus/química , Hepatite C/imunologia , Hepatite C/microbiologia , Anticorpos Anti-Hepatite C , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , RNA Viral/análise
5.
J Viral Hepat ; 1(1): 73-7, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-8790562

RESUMO

The aim of this study was to determine if using hepatitis C antibody (anti-HCV) enzyme immunoassay version 2.0 (EIA2) in addition to version 1.0 (EIA1) increased the safety of the blood supply. Blood non-reactive by anti-HCV EIA1 was transfused in 1990-92. Stored samples from 40098 units, donated prior to 13 March 1992 were later tested by EIA2. For donor units reactive for anti-HCV by EIA2, a recombinant immunoblot assay (RIBA2) was also carried out. In 63 cases, recipients of transfusions which were EIA2 negative or EIA2 reactive were tested for anti-HCV and elevated alanine aminotransferase (ALT) levels 9-12 months after transfusion; pretransfusion anti-HCV status of recipients was unknown. Among these multitransfused patients receiving units that were negative by both EIA1 and EIA2, 1/26 (4%) had anti-HCV. Among transfusion recipients of units negative by EIA1, but who received at least one unit reactive by EIA2, 4/37 recipients (11%) were anti-HCV reactive (P = 0.59). For the recipients of EIA2 reactive blood, when the donor unit was RIBA2 non-reactive, 0/23 recipients were reactive by anti-HCV. Among the recipients of a RIBA2 indeterminate unit, 1/10 recipients had anti-HCV, but for patients who received at least one RIBA2 reactive unit, 3/4 recipients had anti-HCV (P = 0.03). Hence, second-generation anti-HCV testing detected additional units capable of transmitting hepatitis C that were not detected by first-generation testing. However, RIBA2 is a more specific method than EIA2 for determining units capable of transmitting HCV.


Assuntos
Doadores de Sangue , Anticorpos Anti-Hepatite C/sangue , Hepatite C/prevenção & controle , Reação Transfusional , Idoso , Feminino , Humanos , Técnicas Imunoenzimáticas , Masculino , Pessoa de Meia-Idade
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