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1.
PLoS One ; 14(9): e0222200, 2019.
Article in English | MEDLINE | ID: mdl-31513682

ABSTRACT

INTRODUCTION: The aim of this study was to determine the rate of asymptomatic carriage and spread of multidrug-resistant micro-organisms (MDRO) and to identify risk factors for extended spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) carriage in 12 long term care facilities (LTCFs) in Amsterdam, the Netherlands. MATERIALS AND METHODS: From November 2014 to august 2015, feces and nasal swabs from residents from LTCFs in Amsterdam, the Netherlands were collected and analyzed for presence of multidrug-resistant Gram-negative bacteria (MDRGN), including ESBL-E, carbapenemase-producing Enterobacteriaceae (CPE), colistin-resistant Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Logistic regression analysis was performed to assess associations between variables and ESBL-carriage. RESULTS: In total, 385 residents from 12 LTCFs (range 15-48 residents per LTCF) were enrolled. The prevalence of carriage of MDRGN was 18.2% (range among LTCFs 0-47%) and the prevalence of ESBL-E alone was 14.5% (range among LTCFs: 0-34%). Of 63 MDRGN positive residents, 50 (79%) were ESBL-E positive of which 43 (86%) produced CTX-M. Among 44 residents with ESBL-E positive fecal samples of whom data on contact precautions were available at the time of sampling, only 9 (20%) were already known as ESBL-E carriers. The prevalence for carriage of MRSA was 0.8% (range per LTCF: 0-7%) and VRE 0%. One CPE colonized resident was found. All fecal samples tested negative for presence of plasmid mediated resistance for colistin (MCR-1). Typing of isolates by Amplified Fragment Length Polymorphism (AFLP) showed five MDRGN clusters, of which one was found in multiple LTCFs and four were found in single LTCFs, suggesting transmission within and between LTCFs. In multivariate analysis only the presence of MDRO in the preceding year remained a risk factor for ESBL-E carriage. CONCLUSIONS: The ESBL-carriage rate of residents in LTCFs is nearly two times higher than in the general population but varies considerably among LTCFs in Amsterdam, whereas carriage of MRSA and VRE is low. The majority (80%) of ESBL-E positive residents had not been detected by routine culture of clinical specimens at time of sampling. Current infection control practices in LTCFs in Amsterdam do not prevent transmission. Both improvement of basic hygiene, and funding for laboratory screening, should allow LTCFs in Amsterdam to develop standards of care to prevent transmission of ESBL-E.


Subject(s)
Cross Infection/epidemiology , Drug Resistance, Multiple/genetics , Enterobacteriaceae/genetics , Aged , Aged, 80 and over , Drug Resistance, Multiple, Bacterial/genetics , Enterobacteriaceae/metabolism , Enterobacteriaceae Infections/microbiology , Female , Gram-Negative Bacteria/isolation & purification , Gram-Negative Bacterial Infections/etiology , Health Facilities , Humans , Infection Control/methods , Long-Term Care , Male , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Middle Aged , Netherlands/epidemiology , Prevalence , Risk Factors , Skilled Nursing Facilities , Staphylococcal Infections/microbiology , Vancomycin-Resistant Enterococci/isolation & purification
2.
PLoS One ; 10(11): e0141765, 2015.
Article in English | MEDLINE | ID: mdl-26528549

ABSTRACT

This paper describes the trends in prevalence of ESBL producing Enterobacteriaceae (ESBL-E) and ESBL genes, measured in five consecutive yearly Point Prevalence Surveys (PPS). All patients present in the hospital and in a day-care clinic (including patients on dialysis) on the day of the survey, were screened for perianal ESBL-E carriage. Perianal swabs were taken and cultured using an enrichment broth and a selective agar plate. Both phenotypic and genotypic methods were used to detect the production of ESBL, presence of ESBL-genes and clonal relatedness. Out of 2,695 patients, 135 (5.0%) were tested ESBL-E positive. The overall ESBL-E prevalence was stable over the years. Overall 5.2% of all ESBL-E were acquired by nosocomial transmission. A relative decrease of CTX-M-1-1-like ESBL genes (from 44 to 25%, p = 0.026) was observed, possibly related to the strong (>60%) decrease in antibiotic use in livestock in our country during the same period.


Subject(s)
Enterobacteriaceae Infections/epidemiology , Enterobacteriaceae/enzymology , beta-Lactamases/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/pharmacology , Child , Child, Preschool , Cluster Analysis , Enterobacteriaceae/drug effects , Enterobacteriaceae/isolation & purification , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae Infections/transmission , Female , Genotype , Hospitals, Teaching , Humans , Infant , Infant, Newborn , Male , Middle Aged , Netherlands , Phenotype , Prevalence , Young Adult , beta-Lactamases/metabolism
3.
Nurse Educ Today ; 35(12): 1257-61, 2015 Dec.
Article in English | MEDLINE | ID: mdl-25943280

ABSTRACT

Simulation has become a widely used and established pedagogy for teaching clinical nursing skills. Nevertheless, the evidence in favour of this pedagogical approach is weak, and more knowledge is needed in support of its use. The aim of this study was (a) to explore the experiences of undergraduate nursing students when examining knowledge, skills and competences in clinical simulation laboratories with high-fidelity patient simulators and (b) to analyse these students' learning experiences during the examination. A phenomenological approach was used, and qualitative interviews were conducted among 23 second-year undergraduate nursing students-17 women and 6 men. The findings revealed that, irrespective of whether they passed or failed the examination, it was experienced as a valuable assessment of the students' knowledge and skills. Even if the students felt that the examination was challenging, they described it as a learning opportunity. In the examination, the students were able to integrate theory with practice, and earlier established knowledge was scrutinised when reflecting on the scenarios. The examination added aspects to the students' learning that prepared them for the real world of nursing in a safe environment without risking patient safety. The study findings suggest that examinations in clinical simulation laboratories can be a useful teaching strategy in nursing education. The use of high-fidelity patient simulators made the examination authentic. The reflections and feedback on the scenario were described as significant for the students' learning. Undergraduate nursing students can improve their knowledge, understanding, competence and skills when such examinations are performed in the manner used in this study.


Subject(s)
Clinical Competence , Education, Nursing, Baccalaureate , Manikins , Simulation Training , Female , Health Knowledge, Attitudes, Practice , Humans , Male , Nursing Education Research , Students, Nursing/psychology
4.
J Clin Virol ; 58(1): 79-83, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23731844

ABSTRACT

BACKGROUND: The significance of isolation of herpes simplex virus (HSV) type 1 from the lower respiratory tract in critically ill patients on mechanical ventilation is still unclear. In the current study, we used polymerase chain reaction techniques to quantify HSV-1 to further evaluate its role. OBJECTIVES: The hypothesis was that high loads reflect invasive pulmonary disease related to prolonged mechanical ventilation and increased mortality, as opposed to shedding from the upper respiratory tract, which leads to lower viral loads. STUDY DESIGN: We prospectively studied 77 consecutive patients admitted to the intensive care unit and analyzed 136 tracheal aspirates or bronchoalveolar lavage fluids, taken when clinically indicated in the diagnostic workup of fever, radiologic pulmonary infiltrates, progressive respiratory insufficiency or combinations. Samples were cultured for bacteria and yeasts according to routine microbiological methods and HSV-1 loads were determined by real time quantitative PCR. Viral loads were expressed per number of cells recovered. RESULTS: HSV-1 load was directly related to the simplified acute physiology score II (rs=0.47, P=0.04) when the first specimen taken proved positive for HSV-1. HSV-1 positivity concurred with Candida spp. colonization. Patients with and without a HSV-1 load did not differ with respect to pulmonary and systemic courses and vital outcomes. CONCLUSIONS: The data suggest that HSV-1 in the lower respiratory tract originates from shedding in the upper respiratory tract in about 30% of critically ill patients, following immune suppression and reactivation, without invasively infecting the lung. No attributable mortality was observed.


Subject(s)
Herpesvirus 1, Human/isolation & purification , Respiratory Tract Infections/pathology , Respiratory Tract Infections/virology , Viral Load , Adolescent , Adult , Aged , Aged, 80 and over , Bacteria/isolation & purification , Candida/isolation & purification , Critical Illness , Female , Humans , Male , Middle Aged , Prospective Studies , Respiration, Artificial/adverse effects , Young Adult
5.
Transfusion ; 51(10): 2118-24, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21985045

ABSTRACT

BACKGROUND: In this study it was investigated whether Propionibacterium acnes present in platelet concentrates (PCs) and related red blood cells (RBCs), originate from the skin of the donor. STUDY DESIGN AND METHODS: P. acnes that were cultured throughout 2007 and 2008 from PCs and their accompanying RBCs and in 2010 from the phlebotomy site of a selection of the respective donors (n = 22) were typed by amplified fragment length polymorphism. A part of the strains was also determined to species level by sequencing of the 16S rRNA and recA genes. RESULTS: Three different phylogenetic groups of P. acnes were found. The distribution of the P. acnes in three groups was confirmed by sequencing of the recA gene. All strains that were found in PCs and their accompanying RBCs were identical, which indicates that the strain is already present in the whole blood donation. P. acnes could be found on the skin of almost all screened donors. In eight of 22 cases (36.4%), one of the strains from the donor skin was identical to the strains found in PCs and their accompanying RBCs. In two other cases the strains belonged to the same phylogenetic group. CONCLUSION: This study supports the theory that the source of P. acnes contamination is in many cases the skin of the donor. However, further study is necessary to rule out other sources of contamination. Because it is difficult to prevent bacterial contamination by P. acnes completely, it is necessary to further investigate the clinical significance of blood products contaminated with P. acnes.


Subject(s)
Blood Donors , Blood/microbiology , Propionibacterium acnes/genetics , Skin/microbiology , Amplified Fragment Length Polymorphism Analysis , Blood Platelets/microbiology , DNA, Bacterial/analysis , Humans , Netherlands , Phylogeny , Polymerase Chain Reaction , Propionibacterium acnes/isolation & purification , RNA, Ribosomal, 16S/analysis , Rec A Recombinases/genetics , Sequence Analysis, DNA
6.
Transfusion ; 51(9): 2006-11, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21392020

ABSTRACT

BACKGROUND: In this study the applicability of a 16S rRNA real-time reverse transcriptase polymerase chain reaction (RT-PCR) and a Staphylococcus genus-specific PCR for screening of bacterial contamination in platelet concentrates (PCs) was determined. STUDY DESIGN AND METHODS: A total of 336 sample bags, from PCs that were routinely tested in the BacT/ALERT (bioMérieux), were collected and frozen until testing by the PCR assays. Based on the BacT/ALERT results, 107 PCs were positive and 229 were negative for bacterial growth. RESULTS: The analytical sensitivity of the 16S rRNA real-time RT-PCR ranged from 5 to 40 colony-forming units (CFUs)/mL. The PCR detected five positive samples, four of which were also positive in the BacT/ALERT. The sensitivity of the test was 3.8%, and the specificity was 99.5%. The analytical sensitivity of the Staphylococcus genus-specific PCR ranged from 5 to 15 CFUs/mL. Thirty-nine units that were BacT/ALERT positive for staphylococci were tested with this PCR. Six samples were positive with the PCR, five of which were also BacT/ALERT positive. The sensitivity of the Staphylococcus genus-specific PCR was 12.8%, and the specificity was 98.8%. CONCLUSION: Despite the rapid availability of results compared to the BacT/ALERT, the analytical sensitivity of a generic or specific PCR assay is not high enough to be an alternative for the BacT/ALERT when PCs are screened on the day of production.


Subject(s)
Bacteria/isolation & purification , Blood Platelets/microbiology , Reverse Transcriptase Polymerase Chain Reaction/methods , Bacteria/classification , Bacteria/genetics , Humans , RNA, Ribosomal, 16S/genetics , Reproducibility of Results
7.
J Med Microbiol ; 60(Pt 5): 592-599, 2011 May.
Article in English | MEDLINE | ID: mdl-21212143

ABSTRACT

Transfusion-associated bacterial sepsis is the most common microbiological risk of transfusion and is caused mostly by platelet concentrates (PCs). The most frequently identified bacterial contaminants of PCs are coagulase-negative staphylococci (CNS). In order to learn more about the distribution, source and risk of the CNS that are involved in bacterial contamination of PCs, CNS strains isolated during platelet screening were collected and characterized to the species level with three different methods: 16S rRNA and sodA gene sequencing, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and amplified fragment length polymorphism (AFLP) analysis. AFLP analysis was also used for the typing of the CNS strains. A total of 83 CNS strains were analysed by sequencing and 8 different CNS species were identified, with Staphylococcus epidermidis being the predominant species. MALDI-TOF MS and AFLP analysis confirmed these results to a large extent. However, MALDI_TOF MS could not identify all strains to the species level and AFLP analysis revealed an additional, likely novel, CNS species. The species identified are mainly recognized as being part of the normal skin flora. Typing of the CNS strains by AFLP analysis showed that there was not a unique strain which is significantly more often present during bacterial contamination of PCs.


Subject(s)
Blood Platelets/microbiology , Platelet Transfusion/adverse effects , Sepsis/transmission , Staphylococcal Infections/transmission , Staphylococcus/isolation & purification , Amplified Fragment Length Polymorphism Analysis , Bacterial Proteins/genetics , Bacterial Typing Techniques , Base Sequence , Coagulase/metabolism , DNA Primers/genetics , Genes, Bacterial , Humans , Netherlands , RNA, Bacterial/genetics , RNA, Ribosomal, 16S/genetics , Sepsis/blood , Sepsis/microbiology , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Staphylococcal Infections/blood , Staphylococcal Infections/microbiology , Staphylococcus/classification , Staphylococcus/enzymology , Staphylococcus/genetics , Staphylococcus epidermidis/classification , Staphylococcus epidermidis/enzymology , Staphylococcus epidermidis/genetics , Staphylococcus epidermidis/isolation & purification , Superoxide Dismutase/genetics
8.
J Clin Microbiol ; 48(11): 3923-7, 2010 Nov.
Article in English | MEDLINE | ID: mdl-20826645

ABSTRACT

In the Netherlands, there is an ongoing and unparalleled outbreak of Q fever. Rapid and reliable methods to identify patients infected with Coxiella burnetii, the causative agent of Q fever, are urgently needed. We evaluated the performance of different DNA extraction methods and real-time PCR assays that are in use in seven diagnostic or reference laboratories in the Netherlands. A low degree of variation in the sensitivities of most of the developed real-time PCR assays was observed. However, PCR assays amplifying short DNA fragments yielded better results than those producing large DNA fragments. With regard to DNA extraction, the automated MagNA Pure Compact system and the manual QIAamp DNA mini kit consistently yielded better results than either the MagNA Pure LC system and NucliSens EasyMag (both automated) or the High Pure viral nucleic acid kit (manual). The present study shows that multiple combinations of DNA extraction kits and real-time PCR assays offer equivalent solutions to detect C. burnetii DNA in serum samples from patients suspected to have Q fever.


Subject(s)
Bacteriological Techniques/methods , Coxiella burnetii/isolation & purification , DNA, Bacterial/genetics , DNA, Bacterial/isolation & purification , Polymerase Chain Reaction/methods , Q Fever/diagnosis , Serum/microbiology , Coxiella burnetii/genetics , Humans , Netherlands , Q Fever/microbiology , Reproducibility of Results , Sensitivity and Specificity
9.
Transfusion ; 50(6): 1352-8, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20113449

ABSTRACT

BACKGROUND: The sensitivity of a real-time polymerase chain reaction (PCR) assay detecting bacteria in platelet concentrates (PCs) was improved by detection of ribosomal RNA (rRNA) in addition to DNA. The real-time reverse transcription-PCR (RT-PCR) assay was compared with the BacT/ALERT culturing system (bioMérieux) to determine its value for routine screening of PCs for bacterial contamination. STUDY DESIGN AND METHODS: The sensitivity of the assay was determined by spiking PCs with serial dilutions of bacteria. RNA amplification was performed with real-time RT-PCR, using a universal primer and probe set based on the conserved 16S rRNA gene of bacteria. Routinely prepared PCs in plasma were spiked with low bacterial titers of four different bacteria to compare the real-time RT-PCR with the BacT/ALERT. For the BacT/ALERT, samples were taken directly after spiking. For the real-time RT-PCR, samples were taken daily during 7 days of storage. RESULTS: RNA detection improved the sensitivity of the PCR assay at least 10-fold. When PCs were spiked with low bacterial titers, all positive samples were detected by the real-time RT-PCR after 48 hours. The BacT/ALERT became positive for almost all samples within 24 hours. However, some positive PC samples remained negative in the BacT/ALERT. CONCLUSION: The sensitivity of the PCR assay was improved by detection of rRNA. A spiking study demonstrated the advantage of late sampling for PCR testing compared to early sampling for culturing with the BacT/ALERT system. A real-time RT-PCR assay that is performed on PCs during storage or shortly before transfusion can be a good alternative to culturing methods.


Subject(s)
Blood Platelets/microbiology , Escherichia coli , RNA, Bacterial/analysis , RNA, Ribosomal/analysis , Reverse Transcriptase Polymerase Chain Reaction/methods , Staphylococcus epidermidis , Blood Preservation , Humans , RNA, Bacterial/genetics , RNA, Ribosomal/genetics , Sensitivity and Specificity
10.
J Clin Microbiol ; 48(4): 1195-200, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20164281

ABSTRACT

Despite FDA approval and CE marking of commercial tests, manufacturer-independent testing of the technical aspects of newly developed tests is important. To evaluate the analytical performance and explore the clinical applicability of the new Roche COBAS AmpliPrep COBAS TaqMan HIV-1 test, version 2.0 (CAP/CTM v2.0), platform comparison was performed with the Roche CAP/CTM test, version 2.0, the COBAS Amplicor HIV-1 Monitor Test, version 1.5 (CAP/CA v1.5), the COBAS AmpliPrep COBAS TaqMan HIV-1 Test (CAP/CTM v1.0), and the Abbott m2000 RealTime HIV-1 assay on panels and diagnostic samples. Specificity was tested for HIV-2 samples. Furthermore, samples from HIV-1-seropositive individuals with CAP/CA v1.5-measured viral loads below 50 HIV-1 RNA copies per ml (cp/ml) and replicates of HIV-1-seronegative plasma were tested in a checkerboard analysis. CAP/CTM v2.0 is HIV-1 specific, with broad genotype inclusivity and no serious underquantification of viral load relative to the other assays used. Low viral loads below the threshold of quantification for CAP/CA v1.5 are observed with CAP/CTM v2.0. A CAP/CTM v2.0-measured viral load of >50 copies/ml in these samples correlated with therapy failure. In conclusion, CAP/CTM v2.0 is an accurate and reliable test for HIV-1 viral load measurement relative to the other assays used with respect to specificity, sensitivity, and genotype inclusivity.


Subject(s)
HIV Infections/virology , HIV-1/isolation & purification , RNA, Viral/blood , Reagent Kits, Diagnostic , Viral Load/methods , HIV Infections/diagnosis , HIV-1/genetics , Humans , Sensitivity and Specificity
11.
Scand J Infect Dis ; 39(11-12): 1071-3, 2007.
Article in English | MEDLINE | ID: mdl-17852948

ABSTRACT

Of 21 patients diagnosed with Whipple's disease (WD) by polymerase chain reaction (PCR), 3 were mentally retarded. We describe 2 of these patients, both of whom had WD in the central nervous system. WD was confirmed with PCR on blood and, for 1 patient, also on cerebrospinal fluid (CSF).


Subject(s)
Intellectual Disability/complications , Whipple Disease/diagnosis , Adult , Anti-Bacterial Agents/therapeutic use , Female , Humans , Polymerase Chain Reaction , Whipple Disease/blood , Whipple Disease/cerebrospinal fluid , Whipple Disease/drug therapy
12.
Am J Sports Med ; 35(12): 2109-17, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17703002

ABSTRACT

BACKGROUND: It has been suggested that neuromuscular function is of importance in the overall outcome after anterior cruciate ligament (ACL) injury. HYPOTHESIS: Good neuromuscular function can be achieved and maintained over time in subjects with ACL injury treated with rehabilitation and activity modification but without reconstructive surgery. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: One hundred consecutive patients (42 women and 58 men) with acute ACL injury at a nonprofessional, recreational or competitive activity level were assessed 1, 3, and 15 years after injury. Their mean age at inclusion was 26 years (range, 15-43 years). All patients initially underwent rehabilitation and were advised to modify their activity level, especially by avoiding contact sports. Patients with recurrent giving-way episodes or secondary meniscal injuries that required fixation were subsequently excluded and underwent reconstruction of the ACL. Sixty-seven patients (71% of those available for follow-up) with unilateral nonreconstructed injury remained at the 15-year follow-up. Fifty-six of these 67 patients were examined with the single-legged hop test for distance and knee muscle strength. The limb symmetry index (LSI), calculated by dividing the result for the injured leg by that of the uninjured leg and multiplying by 100, was used for comparisons over time (paired t test). RESULTS: The LSI for the single-legged hop test was higher at the 3-year follow-up (mean, 98.5%; standard deviation [SD], 7.6%) than at the 15-year follow-up (mean, 94.8%; SD, 10.5%) (mean difference, -3.7%; 95% confidence interval [CI], -6.1% to -1.2%; P = .004). The LSI for isometric extension was higher at the 15-year follow-up (mean, 97.2%; SD, 13.7%) than at the 1-year follow-up (mean, 88.2%; SD, 15.4%) (mean difference, 9.0%; 95% CI, 3.7% to 14.4%; P = .001). At the 15-year follow-up, between 69% and 85% of the patients had an LSI >or= 90%. CONCLUSIONS: Good functional performance and knee muscle strength can be achieved and maintained over time in the majority of patients with ACL injury treated with rehabilitation and early activity modification but without reconstructive surgery.


Subject(s)
Anterior Cruciate Ligament Injuries , Exercise/physiology , Knee Injuries/rehabilitation , Knee Joint/physiology , Muscle Strength/physiology , Adolescent , Adult , Anterior Cruciate Ligament/physiology , Female , Follow-Up Studies , Humans , Knee Injuries/physiopathology , Male , Muscle, Skeletal/physiology , Prospective Studies
13.
Vaccine ; 25(1): 72-84, 2007 Jan 02.
Article in English | MEDLINE | ID: mdl-16914236

ABSTRACT

The meningococcal iron-limitation-inducible outer membrane protein FrpB (FetA) has been shown to induce bactericidal antibodies, and is, therefore, considered a vaccine candidate. However, these antibodies are strain specific and, consistently, epitope mapping showed that they are directed against a region, located in a surface-exposed loop, L5, that displays considerable sequence variability between strains. Here, we attempted to redirect the immune response to more conserved domains of the protein by deleting L5. Immunization with an FrpB protein lacking L5 resulted in a bactericidal antibody response, and epitope mapping showed that these antibodies were directed against loop L3, which also displays considerable sequence variability. To re-direct the immune response further, immunizations were performed with an FrpB protein lacking both L5 and L3. The antibodies obtained were not bactericidal. Furthermore, the bactericidal antibodies against L3 were only bactericidal in the absence of L5, and immunofluorescence microscopy experiments showed that L5 efficiently shields other immunogenic cell surface-exposed epitopes outside of this region on living cells. Whereas the ability of micro-organisms to vary surface-exposed domains that are targets for protective immunity has long been established, the current work shows that such domains can be remarkably efficient in shielding other, more conserved epitopes.


Subject(s)
Antigenic Variation , Bacterial Outer Membrane Proteins/chemistry , Bacterial Outer Membrane Proteins/immunology , Neisseria meningitidis/immunology , Amino Acid Sequence , Animals , Antibodies, Bacterial/immunology , Antibodies, Monoclonal/immunology , Antigens, Bacterial/administration & dosage , Antigens, Bacterial/chemistry , Antigens, Bacterial/genetics , Antigens, Bacterial/immunology , Bacterial Outer Membrane Proteins/administration & dosage , Bacterial Outer Membrane Proteins/genetics , Epitope Mapping , Immunization , Immunodominant Epitopes/chemistry , Immunodominant Epitopes/immunology , Iron/metabolism , Meningococcal Vaccines , Mice , Mice, Inbred BALB C , Molecular Sequence Data , Neisseria meningitidis/growth & development , Neisseria meningitidis/metabolism , Peptides/administration & dosage , Peptides/chemistry , Peptides/genetics , Peptides/immunology
14.
Vaccine ; 24(17): 3545-57, 2006 Apr 24.
Article in English | MEDLINE | ID: mdl-16517031

ABSTRACT

The vaccine potential of the Neisseria meningitidis lactoferrin-binding proteins LbpA and LbpB was evaluated. Sequencing and sequence alignments suggested that LbpA is relatively well conserved with variability largely restricted to two surface-exposed loops in a proposed topology model. Consistently, antisera raised against synthetic peptides corresponding to exposed loops generally recognized the LbpA proteins of many different strains. Hence, LbpA was considered an attractive vaccine candidate. LbpB shows a higher degree of sequence variability. For immunisation studies, LbpA was overproduced in N. meningitidis and a histidine-tagged LbpB protein was produced in Escherichia coli. Outer membrane vesicles carrying overproduced LbpA and purified LbpB were used to immunise laboratory animals. The bactericidal activity and cross-reactivity of the antibodies was evaluated using meningococcal strains of various clonal lineages. In addition, LbpB-specific monoclonal antibodies were analysed by Western blots and whole-cell enzyme-linked immunosorbent assays. Our results show that both proteins are immunogenic and able to induce bactericidal antibodies, but that the cross-reactivity of these antibodies is limited.


Subject(s)
Bacterial Outer Membrane Proteins/immunology , Meningococcal Vaccines/immunology , Receptors, Cell Surface/immunology , Vaccines, Synthetic/immunology , Amino Acid Sequence , Animals , Antibodies, Bacterial/blood , Antibodies, Monoclonal/immunology , Bacterial Outer Membrane Proteins/chemistry , Blood Bactericidal Activity , Cross Reactions , Humans , Immune Sera/immunology , Mice , Mice, Inbred BALB C , Molecular Sequence Data , Neisseria meningitidis/immunology , Receptors, Cell Surface/chemistry , Recombinant Proteins/immunology , Sequence Alignment
15.
J Leukoc Biol ; 77(6): 1018-25, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15728714

ABSTRACT

The high-affinity leukotriene B(4) (LTB(4)) receptor, BLT1, is a chemotactic receptor involved in inflammatory responses. In this study, we have explored the regulation of BLT1 expression in human monocytes by pro- and anti-inflammatory cytokines, lipopolysaccharide (LPS), and dexamethasone. We found that proinflammatory mediators, such as interferon-gamma (IFN-gamma), tumor necrosis factor-alpha, and LPS, down-regulated expression, whereas the anti-inflammatory cytokine, interleukin-10, and dexamethasone up-regulated BLT1 mRNA expression. The effect of IFN-gamma on BLT1 mRNA expression was rapidly detectable (<4 h) and concentration-dependent (1-50 ng/ml) and seems to be exerted through a block in transcriptional activity. Alterations in mRNA expression were accompanied by changes in BLT1 surface expression, and receptor down-modulation following IFN-gamma stimulation resulted in a diminished chemotactic response to LTB(4). The regulation of BLT1 mRNA and receptor protein expression was similar to the regulation of the monocyte chemoattractant protein-1 chemokine receptor, CC chemokine recptor 2 (CCR2). Flow cytometric analysis of fresh peripheral blood cells revealed that classical (CD14(++)CD16(-)) monocytes express high levels of BLT1 and CCR2 and that both receptors are down-regulated on CD14(+)CD16(+) monocytes. Apart from providing insight into the regulation of BLT1 in human monocytes, our results reveal a parallel expression and regulation of BLT1 and CCR2, which may help to understand monocyte trafficking during pathophysiological conditions.


Subject(s)
Inflammation Mediators/pharmacology , Monocytes/immunology , Receptors, Leukotriene/metabolism , Chemotaxis/drug effects , Dexamethasone/pharmacology , Down-Regulation , Humans , Interferon-gamma/pharmacology , Interleukin-10/pharmacology , Lipopolysaccharides/pharmacology , Monocytes/drug effects , RNA Stability , RNA, Messenger/analysis , RNA, Messenger/metabolism , Receptors, Leukotriene/genetics , Receptors, Leukotriene B4 , Receptors, Purinergic P2 , Tumor Necrosis Factor-alpha/pharmacology , Up-Regulation
16.
Blood ; 105(3): 1274-9, 2005 Feb 01.
Article in English | MEDLINE | ID: mdl-15454480

ABSTRACT

Biosynthesis of leukotrienes (LTs) occurs in human myeloid cells and B lymphocytes. However, the function of leukotrienes in B lymphocytes is unclear. Here, we report that B-cell chronic lymphocytic leukemia (B-CLL) cells produce leukotriene B(4), and that specific leukotriene biosynthesis inhibitors counteracted CD40-dependent activation of B-CLL cells. Studies on the expression of the high-affinity receptor for LTB(4) (BLT1) by flow cytometry analysis showed that the receptor was expressed, to a varying degree, in all investigated B-CLL clones. At a concentration of 100 nM, the drugs BWA4C (a specific 5-lipoxygenase inhibitor) and MK-886 (a specific 5-lipoxygenase activating protein inhibitor) markedly inhibited CD40-induced DNA synthesis (45% and 38%, respectively) and CD40-induced expression of CD23, CD54, and CD150. Addition of exogenous LTB(4) (150 nM) almost completely reversed the effect of the inhibitors on DNA synthesis and antigen expression. Taken together, the results of the present study suggest that leukotriene biosynthesis inhibitors may have a therapeutic role in B-CLL.


Subject(s)
Antigens, CD/physiology , Leukemia, Lymphocytic, Chronic, B-Cell/pathology , Leukotriene B4/pharmacology , Aged , Cell Adhesion Molecules , Female , Humans , Lipoxygenase Inhibitors/pharmacology , Male , Tumor Cells, Cultured
17.
Int Immunopharmacol ; 3(10-11): 1467-75, 2003 Oct.
Article in English | MEDLINE | ID: mdl-12946443

ABSTRACT

We have previously raised two monoclonal antibodies (7B1, 14F11) recognizing the high-affinity leukotriene B4 receptor, BLT1. They were presently used to determine receptor surface expression in the hematopoietic system. In peripheral blood, BLT1 was primarily recognized in granulocytes, monocytes and, to a lower extent, in certain lymphocytes except the CD4 subpopulation. The expression pattern was similar in bone marrow cells. In vitro differentiation of CD34+ progenitor cells induced BLT1 expression within 7 days, which remained constant up to day 17 when a further increase was measured and maintained up to day 20. BLT1 expression was modified by inflammatory mediators: LPS, TNFalpha, fMLP, as well as LTB4 itself, caused a slight down-regulation at 30 min, an effect that was particularly marked with PMA, whereas the effect was least pronounced with IL-8. The antibodies have proved to be useful in an extensive mapping of BLT1 in both peripheral blood and bone marrow and as a tool to elucidate changes in the receptor expression.


Subject(s)
Antibodies, Monoclonal/immunology , Bone Marrow Cells/metabolism , Granulocytes/metabolism , Monocytes/metabolism , Receptors, Leukotriene B4/biosynthesis , Adult , Bone Marrow Cells/immunology , Flow Cytometry , Granulocytes/immunology , Humans , Monocytes/immunology , Receptors, Leukotriene B4/immunology
18.
Arterioscler Thromb Vasc Biol ; 23(10): 1761-7, 2003 Oct 01.
Article in English | MEDLINE | ID: mdl-12947016

ABSTRACT

OBJECTIVE: Leukotriene B4 (LTB4) has been implicated in the trafficking of monocytes to inflammatory pathologic conditions, such as transplant rejection and atherosclerosis. The aim of this study was to determine the mechanisms by which LTB4 contributes to monocyte capture from the circulation. METHODS AND RESULTS: In in vitro and in vivo vascular models, the lipid chemoattractant LTB4 was an equipotent agonist of monocyte adhesion compared with the chemokine monocyte chemoattractant protein-1 (MCP-1). Adenoviral gene transfer of specific endothelial adhesion molecules and blocking monoclonal antibody studies demonstrated that LTB4 triggers both beta1- and beta2-integrin-dependent adhesion. Flow cytometry studies suggested that changes in integrin avidity or affinity, rather than alterations of integrin surface expression, were responsible for the chemoattractant-triggered arrest. Surprisingly, in contrast to the peptide chemokine MCP-1, LTB4 did not activate the phosphoinositide 3-kinase pathway, which is a functionally critical step in chemokine-triggered effector functions. CONCLUSIONS: LTB4 is a potent trigger of monocyte adhesion under flow yet mediates its effects via pathways that appear to differ from peptide chemoattractants. A better understanding of the mechanisms of LTB4-induced monocyte trafficking might shed insight into disease pathogenesis and pinpoint critical steps for therapeutic intervention for multiple human inflammatory pathologic conditions.


Subject(s)
Leukotriene B4/physiology , Monocytes/physiology , Receptors, Leukotriene B4/physiology , Animals , Cell Adhesion/drug effects , Cell Adhesion/physiology , Cells, Cultured , Chemokine CCL2/physiology , Chemotactic Factors/pharmacology , Endothelium, Vascular , Flow Cytometry , Humans , Mesenteric Arteries , Monocytes/chemistry , Rats , Rats, Sprague-Dawley , Receptors, Leukotriene B4/analysis , Receptors, Leukotriene B4/antagonists & inhibitors , Signal Transduction
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