226 research outputs found
Large differences between test strategies for the detection of anti-Borrelia antibodies are revealed by comparing eight ELISAs and five immunoblots
We investigated the influence of assay choice on the results in a two-tier testing algorithm for the detection of anti-Borrelia antibodies. Eighty-nine serum samples from clinically well-defined patients were tested in eight different enzyme-linked immunosorbent assay (ELISA) systems based on whole-cell antigens, whole-cell antigens supplemented with VlsE and assays using exclusively recombinant proteins. A subset of samples was tested in five immunoblots: one whole-cell blot, one whole-cell blot supplemented with VlsE and three recombinant blots. The number of IgM- and/or IgG-positive ELISA results in the group of patients suspected of Borrelia infection ranged from 34 to 59%. The percentage of positives in cross-reactivity controls ranged from 0 to 38%. Comparison of immunoblots yielded large differences in inter-test agreement and showed, at best, a moderate agreement between tests. Remarkably, some immunoblots gave positive results in samples that had been tested negative by all eight ELISAs. The percentage of positive blots following a positive ELISA result depended heavily on the choice of ELISA–immunoblot combination. We conclude that the assays used to detect anti-Borrelia antibodies have widely divergent sensitivity and specificity. The choice of ELISA–immunoblot combination severely influences the number of positive results, making the exchange of test results between laboratories with different methodologies hazardous
Nationwide outbreak of STEC O157 infection in the Netherlands, December 2008-January 2009: continuous risk of consuming raw beef products.
The Netherlands experienced a nationwide outbreak of Shiga toxin-producing Escherichia coli (STEC) O157 with onset of symptoms from the end of December 2008 until the end of January 2009. A total of 20 laboratory-confirmed cases were linked to the outbreak strain, serotype O157: H-, stx1, stx2, eae and e-hly positive. The investigation into the source of this outbreak is still ongoing, but evidence so far suggests that infection occurred as a result of consuming contaminated raw meat (steak tartare)
Performance predictions for a laser intensified thermal beam for use in high resolution Focused Ion Beam instruments
Photo-ionization of a laser-cooled and compressed atomic beam from a
high-flux thermal source can be used to create a high-brightness ion beam for
use in Focus Ion Beam (FIB) instruments. Here we show using calculations and
Doppler cooling simulations that an atomic rubidium beam with a brightness of
at a current of 1 nA can be created using a
compact 5 cm long 2D magneto-optical compressor which is more than an order of
magnitude better than the current state of the art Liquid Metal Ion Source.Comment: 8 pages, 7 figures submitted to: Phys. Rev.
An Enzyme-Linked Immunosorbent Spot Assay Measuring Borrelia burgdorferi B31-Specific Interferon Gamma-Secreting T Cells Cannot Discriminate Active Lyme Neuroborreliosis from Past Lyme Borreliosis: a Prospective Study in the Netherlands.
Two-tier serology testing is most frequently used for the diagnosis of Lyme borreliosis (LB); however, a positive result is no proof of active disease. To establish a diagnosis of active LB, better diagnostics are needed. Tests investigating the cellular immune system are available, but studies evaluating the utility of these tests on well-defined patient populations are lacking. Therefore, we investigated the utility of an enzyme-linked immunosorbent spot (ELISpot) assay to diagnose active Lyme neuroborreliosis. Peripheral blood mononuclear cells (PBMCs) of various study groups were stimulated by using Borrelia burgdorferi strain B31 and various recombinant antigens, and subsequently, the number of Borrelia-specific interferon gamma (IFN-γ)-secreting T cells was measured. We included 33 active and 37 treated Lyme neuroborreliosis patients, 28 healthy individuals treated for an early manifestation of LB in the past, and 145 untreated healthy individuals. The median numbers of B. burgdorferi B31-specific IFN-γ-secreting T cells/2.5 × 105 PBMCs did not differ between active Lyme neuroborreliosis patients (6.0; interquartile range [IQR], 0.5 to 14.0), treated Lyme neuroborreliosis patients (4.5; IQR, 2.0 to 18.6), and treated healthy individuals (7.4; IQR, 2.3 to 14.9) (P = 1.000); however, the median number of B. burgdorferi B31-specific IFN-γ-secreting T cells/2.5 × 105 PBMCs among untreated healthy individuals was lower (2.0; IQR, 0.5 to 3.9) (P ≤ 0.016). We conclude that the Borrelia ELISpot assay, measuring the number of B. burgdorferi B31-specific IFN-γ-secreting T cells/2.5 × 105 PBMCs, correlates with exposure to the Borrelia bacterium but cannot be used for the diagnosis of active Lyme neuroborreliosis
Precision spectroscopy of helium in a magic wavelength optical dipole trap
Improvements in both theory and frequency metrology of few-electron systems
such as hydrogen and helium have enabled increasingly sensitive tests of
quantum electrodynamics (QED), as well as ever more accurate determinations of
fundamental constants and the size of the nucleus. At the same time advances in
cooling and trapping of neutral atoms have revolutionized the development of
increasingly accurate atomic clocks. Here, we combine these fields to reach the
highest precision on an optical tranistion in the helium atom to date by
employing a Bose-Einstein condensate confined in a magic wavelength optical
dipole trap. The measured transition accurately connects the ortho- and
parastates of helium and constitutes a stringent test of QED theory. In
addition we test polarizability calculations and ultracold scattering
properties of the helium atom. Finally, our measurement probes the size of the
nucleus at a level exceeding the projected accuracy of muonic helium
measurements currently being performed in the context of the proton radius
puzzle
Disagreement between the results from three commercial tests for the detection of Borrelia-specific serum antibodies in the Netherlands associated with antibiotic treatment for Lyme borreliosis: a retrospective study.
The diagnosis of Lyme borreliosis is challenging because of the often non-specific symptoms and persisting antibodies after infection. We investigated the diagnostic characteristics of two enzyme-linked immunosorbent assays (ELISAs) and an immunoblot for the detection of Borrelia-specific serum antibodies using different test strategies in individuals with and without antibiotic treatment for Lyme borreliosis. This retrospective study included healthy individuals, patients with active Lyme neuroborreliosis and patients treated for Lyme neuroborreliosis. Two ELISAs were compared: the C6 ELISA and the SERION ELISA. Equivocal and positive results were confirmed by immunoblot. We included 174 healthy individuals, of whom 27 (15.5%) were treated for Lyme borreliosis in the past, 36 patients were treated for Lyme neuroborreliosis and 27 patients had active Lyme neuroborreliosis. All the active Lyme neuroborreliosis patients were reactive in both ELISAs (100% sensitivity); less reactivity was seen in the other three groups (range 17.7% to 69.4%). The concordance between the ELISA results was high in active Lyme neuroborreliosis patients (26/27; 96.3%) and healthy individuals (131/147; 89.1%), but lower in treated healthy individuals (18/27; 66.7%) and treated Lyme neuroborreliosis patients (18/36; 50.0%) (p ≤ 0.005). This study showed that antibiotic treatment against Lyme borreliosis was strongly associated with discordant ELISA and test strategy results (odds ratio: 10.52; p < 0.001 and 9.98; p = 0.014, respectively) suggesting antibiotic treatment influences the pace at which the various antibodies directed to the different antigens used in both ELISAs wane. Among treated neuroborreliosis patients, the SERION ELISA stayed positive for a longer period after infection compared to the C6 ELISA. This should be taken into consideration when requesting and/or interpreting Lyme serology
Antimicrobial susceptibility profile of clinically relevant Bacteroides, Phocaeicola, Parabacteroides and Prevotella species, isolated by eight laboratories in the Netherlands
Objectives: Recently, reports on antimicrobial-resistant Bacteroides and Prevotella isolates have increased in the Netherlands. This urged the need for a surveillance study on the antimicrobial susceptibility profile of Bacteroides, Phocaeicola, Parabacteroides and Prevotella isolates consecutively isolated from human clinical specimens at eight different Dutch laboratories. Methods: Each laboratory collected 20–25 Bacteroides (including Phocaeicola and Parabacteroides) and 10–15 Prevotella isolates for 3 months. At the national reference laboratory, the MICs of amoxicillin, amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem, metronidazole, clindamycin, tetracycline and moxifloxacin were determined using agar dilution. Isolates with a high MIC of metronidazole or a carbapenem, or harbouring cfiA, were subjected to WGS. Results: Bacteroides thetaiotaomicron/faecis isolates had the highest MIC 90 values, whereas Bacteroides fragilis had the lowest MIC 90 values for amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem and moxifloxacin. The antimicrobial profiles of the different Prevotella species were similar, except for amoxicillin, for which the MIC 50 ranged from 0.125 to 16 mg/L for Prevotella bivia and Prevotella buccae, respectively. Three isolates with high metronidazole MICs were sequenced, of which one Bacteroides thetaiotaomicron isolate harboured a plasmid-located nimE gene and a Prevotella melaninogenica isolate harboured a nimA gene chromosomally. Five Bacteroides isolates harboured a cfiA gene and three had an IS element upstream, resulting in high MICs of carbapenems. The other two isolates harboured no IS element upstream of the cfiA gene and had low MICs of carbapenems. Conclusions: Variations in resistance between species were observed. To combat emerging resistance in anaerobes, monitoring resistance and conducting surveillance are essential.</p
Studies on the Tannin Decomposing Enzyme of Molds (Part 9) : Acidimetric method for the determination of the enzyme activity
Lymphoproliferative responses (LPRs) to recall antigens (Ags) and human immunodeficiency virus type 1 (HIV-1) Gag and frequencies of circulating HIV-1-specific cytotoxic T lymphocyte precursors (CTLps) were measured in 12 patients undergoing highly active antiretroviral therapy (HAART) after long-standing HIV-1 infection. LPRs to at least 1 recall Ag became detectable or increased in all patients during HAART. No significant LPRs to Gag-p24 were observed, whereas 4 of 8 patients tested presented with Gag-p17-specific LPRs. HIV-1-specific CTLp frequencies became measurable or increased early during therapy in 6 of 10 patients tested and were maintained or decreased thereafter. Increasing HIV-1-specific CTLp frequencies were seen only in association with partial HAART failure in 1 patient. In conclusion, restoration of CD4+ T lymphocyte responsiveness to recall Ags is achieved during HAART. The data provide evidence for limited HIV-1-specific CD4+ memory T cells during advanced HIV-1 infection and suggest that both CD4+ and CD8+ HIV-1-specific T cells are poorly stimulated when viral load is suppresse
A simple 2 W continuous-wave laser system for trapping ultracold metastable helium atoms at the 319.8 nm magic wavelength
Estimation of acute and chronic Q fever incidence in children during a three-year outbreak in the Netherlands and a comparison with international literature
Background:Â In the Dutch 2007-2009 Q fever outbreak Coxiella burnetii was transmitted aerogenically from dairy goat farms to those living in the surrounding areas. Relatively few children were reported. The true number of pediatric infections is unknown. In this study, we estimate the expected number of acute and chronic childhood infections. Methods:Â As Coxiella was transmitted aerogenic to those living near infected dairy goat farms, we could use adult seroprevalence data to estimate infection risk for inhabitants, children and adults alike. Using Statistics Netherlands data we estimated the number of children at (high) risk for developing chronic Q fever. Literature was reviewed for childhood (0-15 years) Q fever reports and disease rates. We compared this with Dutch reported and our estimated data for 2007-2009. Results:Â In The Netherlands epidemic, 44 children were reported (1.2 % of total notifications). The childhood incidence was 0.15 compared to 2.6 per 10,000 inhabitants for adults. No complications were reported. Based on the expected similarity in childhood and adult exposure we assume that 9.8 % of children in the high-risk area had Q fever infection, resulting in 1562 acute infections during the Q fever epidemic interval. Based on the prevalence of congenital heart disease, at least 13 children are at high risk for developing chronic Q fever. In medical literature, 42 case reports described 140 childhood Q fever cases with a serious outcome (four deaths). In chronic Q fever, cardiac infections were predominant. Four outbreaks were reported involving children, describing 11 childhood cases. 36 National and/or regional studies reported seroprevalences varying between 0 and 70 %. Conclusion:Â In the 3-year Dutch epidemic, few childhood cases were reported, with pulmonary symptoms leading, and none with a serious presentation. With an estimated 13 high-risk children for chronic infection in the high exposure area, and probably forty in the whole country, we may expect several chronic Q fever complications in the coming years in paediatric practice
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