Corrigendum to "Genetic diversity and iron metabolism of Staphylococcus hominis isolates originating from bovine quarter milk, rectal feces, and teat apices" (J. Dairy Sci. 105:9995-10006)

Staphylococcus chromogenes TA showed significantly lower growth under iron-deprived conditions, and adding an iron supplement (lactoferrin or ferritin) resulted in no improvement in growth; in contrast, growth of S. chromogenes IM was significantly recovered with ferritin iron supplementation. OnlyStaphylococcus hominis strains originating from quarter milk were able to significantly utilize ferritin as an iron source to reverse the growth inhibition caused by chelating agent 2,2'-bipyridyl in varying degrees. Both S. chromogenes strains (IM and TA) and all S. hominis strains were unable to significantly use lactoferrin as an iron source for growth recovery.

Comparison of non-aureus staphylococcal and mammaliicoccal species found in both composite milk and bulk-tank milk samples of dairy cows collected in tandem

Non-aureus staphylococci and the closely related mammaliicoccal species (NASM) are the most common causes of bovine subclinical mastitis on modern dairy farms and are highly prevalent in bulk-tank milk. The purpose of this study was to determine the distribution of NASM in both composite cow milk (CCM) and bulk-tank milk (BTM) samples collected in tandem in commercial Flemish dairy herds and to estimate the origin of the different (subgroups of) NASM species present in BTM by applying strain typing (random amplification of polymorphic DNA or random amplified DNA [RAPD]). A single cross-sectional sampling was performed over 5 herds that volunteered to participate in the study. Composite cow milk samples (n = 356) were collected from all lactating cows (except those with clinical mastitis) during a milking in tandem with 6 BTM samples per herd sequentially collected immediately post that milking (n = 30). In total, 421 and 80 NASM isolates were recovered and identified by MALDI-TOF mass spectrometry from the CCM and BTM samples, respectively and a total of 21 and 12 different NASM species were identified from CCM and BTM samples, respectively. Staphylococcus cohnii was the most prevalent NASM species found in BTM followed by Staphylococcus haemolyticus, Staphylococcus epidermidis, Mammaliicoccus lentus, and Staphylococcus equorum, whereas from CCM samples the most common species were S. hemolyticus, S. cohnii, S. equorum, S. epidermidis, and Staphylococcus chromogenes. The prevalent NASM species in both CCM and BTM samples was distinct for each herd, corroborating other studies observing a herd-specific NASM microbiota. Random amplified DNA analysis was performed on 9 NASM species (S. chromogenes, S. epidermidis, S. haemolyticus, S. equorum, Mammaliicoccus sciuri, Staphylococcus xylosus, S. cohnii, Staphylococcus debuckii, and M. lentus) because these species were isolated from both sample types in a herd. The same RAPD types were found in both sample types for all NASM species selected for strain typing in varying degrees. When assessing the distribution of NASM species, differences within NASM species should be examined meaning a closer look should be taken at the strain level rather than at the species level only.

Genetic diversity and iron metabolism of Staphylococcus hominis isolates originating from bovine quarter milk, rectal feces, and teat apices

Staphylococcus hominis, a member of the non-aureus staphylococci (NAS) group, is part of the human and animal microbiota. Although it has been isolated from multiple bovine-associated habitats, its relevance as a cause of bovine mastitis is currently not well described. To successfully colonize and proliferate in the bovine mammary gland, a bacterial species must be able to acquire iron from host iron-binding proteins. The aims of this study were (1) to assess the genetic diversity of S. hominis isolated from bovine quarter milk, rectal feces, and teat apices, and (2) to investigate the capacity of bovine S. hominis isolates belonging to these different habitats to utilize ferritin and lactoferrin as iron sources. To expand on an available collection of bovine S. hominis isolates (2 from quarter milk, 8 from rectal feces, and 19 from teat apices) from one commercial dairy herd, a subsequent single cross-sectional quarter milk sampling (n = 360) was performed on all lactating cows (n = 90) of the same herd. In total, 514 NAS isolates were recovered and identified by MALDI-TOF mass spectrometry; the 6 most prevalent NAS species were S. cohnii (33.9%), S. sciuri (16.7%), S. haemolyticus (16.3%), S. xylosus (9.6%), S. equorum (9.4%), and S. hominis (3.5%). A random amplified polymorphic DNA (RAPD) analysis was performed on 46 S. hominis isolates (19 from quarter milk, 8 from rectal feces, and 19 from teat apices). Eighteen distinct RAPD fingerprint groups were distinguished although we were unable to detect the presence of the same RAPD type in all 3 habitats. One S. hominis isolate of a distinct RAPD type unique to a specific habitat (8 from quarter milk, 3 from rectal feces, and 4 from teat apices) along with the quality control strain Staphylococcus aureus ATCC 25923 and 2 well-studied Staphylococcus chromogenes isolates ("IM" and "TA") were included in the phenotypical iron test. All isolates were grown in 4 types of media: iron-rich tryptic soy broth, iron-rich tryptic soy broth deferrated by 2,2'-bipyridyl, and deferrated tryptic soy broth supplemented with human recombinant lactoferrin or equine spleen-derived ferritin. The growth of the different strains was modified by the medium in which they were grown. Staphylococcus chromogenes TA showed significantly lower growth under iron-deprived conditions, and adding an iron supplement (lactoferrin or ferritin) resulted in no improvement in growth; in contrast, growth of S. chromogenes IM was significantly recovered with iron supplementation. Staphylococcus hominis strains from all 3 habitats were able to significantly utilize ferritin but not lactoferrin as an iron source to reverse the growth inhibition, in varying degrees, caused by the chelating agent 2,2'-bipyridyl.

Short communication: Barrier characteristics of 3 external teat sealants to prevent bacterial penetration under in vitro conditions using rubber calf-feeding nipples

The main objective of this study was to evaluate the barrier characteristics of 3 external teat sealants for dry cows in preventing bacterial penetration by 3 common major mastitis pathogens (Escherichia coli, Staphylococcus aureus, and Streptococcus uberis) via a novel in vitro simulation model using rubber calf-feeding nipples. All feeding nipples were filled with a sterile cotton plug soaked in sterile broth heart infusion medium and were treated as follows: rubber teats 1 and 5 were sealed with Ubera Dry (Inovet, Arendonk, Belgium); rubber teats 2 and 6 were sealed with T-Hexx Dry (Huvepharma Livestock, St. Louis, MO); rubber teats 3 and 7 were sealed with Uddergold Dry (Ecolab Food and Beverage Division, St. Paul, MN); and rubber teats 4 and 8 remained unsealed and served as positive and negative controls, respectively. After the dips had dried, rubber teats 1 to 4 were immersed in a suspension of E. coli (experiment 1), Staph. aureus (experiment 2), or Strep. uberis (experiment 3; ≥1.5 × 10⁸ cfu/mL) for 24 h, whereas rubber teats 5 to 8 were not exposed to the bacterial suspensions. All external teat sealants adhered well to the rubber teats. All cotton plugs collected from the teats that were not exposed to E. coli, Staph. aureus, or Strep. uberis (rubber teats 5 to 8) remained culture-negative, except for 1 (due to contamination). Of the rubber teats that were exposed to the major mastitis pathogens, all cotton plugs collected from the teats dipped with Ubera Dry and T-Hexx Dry remained culture-negative for the mastitis pathogen they were exposed to. The cotton plugs of the rubber teats that were sealed with Uddergold Dry and exposed to E. coli and Strep. uberis showed positive cultures for the respective bacteria, as demonstrated using strain-typing. The cotton plugs collected from the rubber teats that were not sealed with an external teat sealant and that served as positive controls became culture-positive for the mastitis pathogens they were exposed to. We conclude that Ubera Dry showed comparable and superior barrier performance against penetration of E. coli, Staph. aureus, and Strep. uberis compared with T-Hexx Dry and Uddergold Dry, respectively, under in vitro conditions using a novel in vitro simulation model. Although one should be aware that the method has not yet been validated to predict risk of intramammary infections, the proposed technique can be a meaningful starting point to evaluate and compare the barrier characteristics of external teat sealants in preventing bacterial penetration. A large-scale clinical trial is needed before any definite conclusions can be drawn as to the adherence, duration of adherence, barrier performance, and efficacy in protection against intramammary infections of the 3 external teat sealants under field conditions.

The Functional Defect of Factor VIII Leiden, a Genetic Variant of Coagulation Factor VIII

Factor VIII Leiden is a genetic variant of coagulation factor VIII which has been detected in the plasma of a patient with mild haemophilia A. In this patient’s plasma factor VIII procoagulant antigen was in 5-fold excess over factor VIII procoagulant activity, indicating the presence of an abnormal factor VIII molecule. The variant factor VIII was isolated from the patient’s plasma, and its functional properties were studied in a factor X-activating system consisting of purified components. The isolated factor VIII Leiden was normally activated by factor Xa and by thrombin, but the activity of the factor Villa was about 3% of normal. The defect of factor Villa Leiden was studied by comparison with normal factor Villa in kinetic experiments of factor Xa formation. The results support the hypothesis that factor Villa Leiden has a reduced affinity for phospholipid-bound factor IXa in the intrinsic factor X-activating complex.

The Role of Factor VIII in the Activation of Human Blood Coagulation Factor X by Activated Factor IX

The role of factor VIII in the activation of human factor X by factor IXa, Ca2+ and phospholipid has been investigated. Factor VIII stimulated the factor Xa formation after activation by factor Xa or thrombin; the activity of thrombin-activated factor VIII was about 4-fold that of factor Xa-activated factor VIII. The isolated procoagulant moiety of the factor VIII complex behaved identically to the complete complex, whereas the von Willebrand factor moiety did not participate in the factor Xa formation. Thrombin-activated factor VIII complex (factor Villa) was used to study the effect of factor Villa in kinetic experiments. The results revealed a complex kinetic behaviour, including substrate inhibition and non-linearity of the reaction rate with the enzyme concentration. Using previously obtained insight into the kinetics of factor X activation in the absence of factor VIII, the results were found to support the hypothesis that factor Villa participates in the factor Xa formation in a complex with phospholipid-bound factor IXa; the formation of the factor VUIa-factor IXa complex then increases the catalytic efficiency of the factor IXa by 500-fold.

Activation of Human Coagulation Factor VIII by Activated Factor X, the Common Product of the Intrinsic and the Extrinsic Pathway of Blood Coagulation

The intrinsic activation of human factor X has been studied in a system consisting of purified factors and in plasma. In both these systems factor Xa stimulated the activation of factor X by factor IXa plus factor VIII This is due to the activation of factor VIII by factor Xa. When this factor Xa is formed via the extrinsic pathway, the extrinsic factor X activator functions as a stimulator of the intrinsic factor X activator.

Protein C Deficiency in a Dutch Family with Thrombotic Disease

A rabbit antibody against human protein C was used for the quantitative estimation of protein C in plasma. In healthy individuals protein C antigen ranged from 0.65-1.45 U/ml. Plasma protein C antigen was found to be independent of either age or sex. Under influence of oral anticoagulant treatment the protein C antigen concentration decreased to 0.47 U/ml (at low intensity treatment) or 0.33 U/ml (at high intensity treatment). Using normal ranges of protein C and protein C/factor II and protein C/factor X ratios criteria were developed for the assessment of protein C deficiency. In a Dutch family with a history of thrombotic disease two members were found to have an isolated protein C deficiency, while a third one is suspected of protein C deficiency. In one case it was possible to confirm the diagnosis of suspected protein C deficiency during temporary withdrawal of the anticoagulant therapy.

Note: Soft X-ray transmission polarizer based on ferromagnetic thin films

A transmission polarizer for producing elliptically polarized soft X-ray radiation from linearly polarized light is presented. The setup is intended for use at synchrotron and free-electron laser beamlines that do not directly offer circularly polarized light for, e.g., X-ray magnetic circular dichroism (XMCD) measurements or holographic imaging. Here, we investigate the degree of ellipticity upon transmission of linearly polarized radiation through a cobalt thin film. The experiment was performed at a photon energy resonant to the Co L₃-edge, i.e., 778 eV, and the polarization of the transmitted radiation was determined using a polarization analyzer that measures the directional dependence of photo electrons emitted from a gas target. Elliptically polarized radiation can be created at any absorption edge showing the XMCD effect by using the respective magnetic element.

Imaging the square of the correlated two-electron wave function of a hydrogen molecule

The toolbox for imaging molecules is well-equipped today. Some techniques visualize the geometrical structure, others the electron density or electron orbitals. Molecules are many-body systems for which the correlation between the constituents is decisive and the spatial and the momentum distribution of one electron depends on those of the other electrons and the nuclei. Such correlations have escaped direct observation by imaging techniques so far. Here, we implement an imaging scheme which visualizes correlations between electrons by coincident detection of the reaction fragments after high energy photofragmentation. With this technique, we examine the H₂ two-electron wave function in which electron–electron correlation beyond the mean-field level is prominent. We visualize the dependence of the wave function on the internuclear distance. High energy photoelectrons are shown to be a powerful tool for molecular imaging. Our study paves the way for future time resolved correlation imaging at FELs and laser based X-ray sources.

Electron-electron correlation is a complex and interesting phenomenon that occurs in multi-electron systems. Here, the authors demonstrate the imaging of the correlated two-electron wave function in hydrogen molecule using the coincident detection of the electron and proton after the photoionization.

Critical Aspects for Detection of Coxiella burnetii

Coxiella burnetii is a globally distributed zoonotic γ-proteobacterium with an obligatory intracellular lifestyle. It is the causative agent of Q fever in humans and of coxiellosis among ruminants, although the agent is also detected in ticks, birds, and various other mammalian species. Requirements for intracellular multiplication together with the necessity for biosafety level 3 facilities restrict the cultivation of C. burnetii to specialized laboratories. Development of a novel medium formulation enabling axenic growth of C. burnetii has facilitated fundamental genetic studies. This review provides critical insights into direct diagnostic methods currently available for C. burnetii. It encompasses molecular detection methods, isolation, and propagation of the bacteria and its genetic characterization. Differentiation of C. burnetii from Coxiella-like organisms is an essential diagnostic prerequisite, particularly when handling and analyzing ticks.

Serological evidence of Francisella tularensis in febrile patients seeking treatment at remote hospitals, northeastern Kenya, 2014-2015

Tularaemia is a highly contagious infectious zoonosis caused by the bacterial agent Francisella tularensis. The aim of this study was to investigate the presence of antibodies to F. tularensis in febrile patients in northeastern Kenya. During 2014-2015, 730 patients were screened for anti-F. tularensis antibodies using a combination of ELISA and Western blot. Twenty-seven (3.7%) individuals were positive for F. tularensis. Tularaemia was not suspected by the treating clinicians in any of them. Our results suggest that tularaemia may be present in Kenya but remain unreported, and emphasizes the need for local clinicians to broaden their diagnostic repertoire when evaluating patients with undifferentiated febrile illness.

Two-Particle Interference of Electron Pairs on a Molecular Level

We investigate the photodouble ionization of H_{2} molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. In contrast, the quasiparticle consisting of both electrons (i.e., the "dielectron") does. The work highlights the fact that nonlocal effects are embedded everywhere in nature where many-particle processes are involved.

The direct impact of landslides on household income in tropical regions: A case study from the Rwenzori Mountains in Uganda

Landslides affect millions of people worldwide, but theoretical and empirical studies on the impact of landslides remain scarce, especially in Sub-Saharan Africa. This study proposes and applies a method to estimate the direct impact of landslides on household income and to investigate the presence of specific risk sharing and mitigation strategies towards landslides in a tropical and rural environment. An original cross-sectional household survey is used in combination with geographical data to acquire detailed information on livelihoods and on hazards in the Rwenzori mountains, Uganda. Ordinary least square regressions and probit estimations with village fixed effects are used to estimate the impact of landslides and the presence of mitigation strategies. Geographical information at household level allows to disentangle the direct impact from the indirect effects of landslides. We show that the income of affected households is substantially reduced during the first years after a landslide has occurred. We find that members of recently affected households participate more in wage-employment or in self-employed activities, presumably to address income losses following a landslide. Yet, we see that these jobs do not provide sufficient revenue to compensate for the loss of income from agriculture. Given that landslides cause localized shocks, finding a significant direct impact in our study indicates that no adequate risk sharing mechanisms are in place in the Rwenzori sub-region. These insights are used to derive policy recommendations for alleviating the impact of landslides in the region. By quantifying the direct impact of landslides on household income in an agricultural context in Africa this study draws the attention towards a problem that has been broadly underestimated so far and provides a sound scientific base for disaster risk reduction in the region. Both the methodology and the findings of this research are applicable to other tropical regions with high landslide densities.

Acute Q fever infection in Thuringia, Germany, after burial of roe deer fawn cadavers (Capreolus capreolus): a case report

We report on a case of a 48-year-old man who presented with acute Q fever infection after burying two fawn cadavers (Capreolus capreolus). Recent outbreaks of Q fever in Europe have been traced back to intensive goat breeding units, sheep flocks in the proximity of highly populated urban areas or to farmed deer. To our knowledge, this is the first case report describing Q fever infection in a human linked to roe deer as a source of infection.

Spectrometer for shot-to-shot photon energy characterization in the multi-bunch mode of the free electron laser at Hamburg

The setup and first results from commissioning of a fast online photon energy spectrometer for the vacuum ultraviolet free electron laser at Hamburg (FLASH) at DESY are presented. With the use of the latest advances in detector development, the presented spectrometer reaches readout frequencies up to 1 MHz. In this paper, we demonstrate the ability to record online photon energy spectra on a shot-to-shot base in the multi-bunch mode of FLASH. Clearly resolved shifts in the mean wavelength over the pulse train as well as shot-to-shot wavelength fluctuations arising from the statistical nature of the photon generating self-amplified spontaneous emission process have been observed. In addition to an online tool for beam calibration and photon diagnostics, the spectrometer enables the determination and selection of spectral data taken with a transparent experiment up front over the photon energy of every shot. This leads to higher spectral resolutions without the loss of efficiency or photon flux by using single-bunch mode or monochromators.

Novel real-time PCR detection assay for Brucella suis

INTRODUCTION

Brucella suis is the causative agent of brucellosis in suidae and is differentiated into five biovars (bv). Biovars 1 and 3 possess zoonotic potential and can infect humans, whereas biovar 2 represents the main source of brucellosis in feral and domestic pigs in Europe. Both aspects, the zoonotic threat and the economic loss, emphasize the necessity to monitor feral and domestic pig populations. Available serological or PCR based methods lack sensitivity and specificity.

RESULTS

Here a bioinformatics approach was used to identify a B. suis specific 17 bp repeat on chromosome II (BS1330_II0657 locus). This repeat is common for B. suis bv 1 to 4 and was used to develop a TaqMan probe assay. The average PCR efficiency was determined as 95% and the limit of detection as 12,5 fg/µl of DNA, equally to 3.7 bacterial genomes. This assay has the highest sensitivity of all previously described B. suis specific PCR assays, making it possible to detect 3-4 bacterial genomes per 1 µl of sample. The assay was tested 100% specific for B. suis and negative for other Brucella spp. and closely related non-Brucella species.

CONCLUSIONS

This novel qPCR assay could become a rapid, inexpensive and reliable screening method for large sample pools of B. suis 1 to 4. This method will be applicable for field samples after validation.

Low zinc and selenium concentrations in sepsis are associated with oxidative damage and inflammation

BACKGROUND

Oxidative stress with dysregulated inflammation are hallmarks of sepsis. Zinc and selenium have important antioxidant functions, such that they could be important in patients with sepsis. We used an in vitro approach to assess the effect of zinc and selenium on oxidative stress, mitochondrial function, and inflammatory responses in conditions mimicking sepsis and related the findings to plasma concentrations and biomarkers in patients with and without sepsis.

METHODS

Human endothelial cells were exposed to a range of zinc and selenium concentrations in conditions mimicking sepsis. Zinc, selenium, and a series of biomarkers of oxidative stress and inflammation were measured in plasma from critically ill patients with and without sepsis.

RESULTS

Culturing cells with different concentrations of zinc caused altered zinc transporter protein expression and cellular zinc content, and selenium affected glutathione peroxidase 3 activity. Although zinc or selenium at physiological concentrations had no effect on interleukin-6 release in vitro, higher concentrations of the trace elements were associated with improved mitochondrial function. Plasma zinc and selenium concentrations were low in patients [zinc: median (range) 4.6 (2.1-6.5) μM in control patients without sepsis and 3.1 (1.5-5.4) μM in patients with sepsis, P=0.002; and selenium: 0.78 (0.19-1.32) μM in control patients and 0.42 (0.22-0.91) μM in sepsis patients, P=0.0009]. Plasma concentrations of interleukin-6, other biomarkers of inflammation, and markers of oxidative damage to proteins and lipids were elevated, particularly in patients with sepsis, and were inversely related to plasma zinc and selenium concentrations.

CONCLUSIONS

Zinc and selenium concentrations were reduced in critically ill patients, with increased oxidative stress and inflammatory biomarkers, particularly in patients with sepsis. Oxidative stress as a result of suboptimal selenium and zinc concentrations might contribute to damage of key proteins.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: registration number NCT01328509.

Isolation of the highly pathogenic and zoonotic agent Burkholderia pseudomallei from a pet green Iguana in Prague, Czech Republic

Background

Melioidosis caused by Burkholderia (B.) pseudomallei is an endemic zoonotic disease mainly reported from northern Australia and Southeast Asia. In Europe, cases of human melioidosis have been reported only from patients travelling to endemic regions. Besides humans, B. pseudomallei has a very broad host range in domestic and wild animals. There are some reports about importation of B. pseudomallei-infected animals from endemic areas into Europe. The present report describes the first case of B. pseudomallei infection of a pet iguana in Europe.

Case presentation

In a 5-year-old pet Iguana iguana living in a private household in Prague, Czech Republic, B. pseudomallei was isolated from pus of an abscess. The isolate VB976100 was identified by Vitek®2, MALDI-TOF mass spectrometry and polymerase chain reaction as B. pseudomallei. The molecular typing resulted in multi-locus sequence type 436 hitherto, which has been found only once worldwide in a B. pseudomallei strain isolated in the USA and originating from Guatemala. The identification as internal transcribed spacer type G indicates a close relatedness to strains mainly isolated in the Western Hemisphere. These findings support the hypothesis that the iguana became infected in this region or in a breeding facility through contact to other infected animals.

Conclusions

The present case highlights the risk of importation of the highly pathogenic and zoonotic B. pseudomallei into non-endemic regions through animal trade. Therefore, veterinarians treating animals from these areas and physicians examining patients owning such animals should include melioidosis in differential diagnosis whenever specific symptoms appear. Furthermore, veterinary authorities responsible for supervision of traders and pet shops should be aware of this risk of zoonotic transmission.

Molecular pathogenesis of the obligate intracellular bacterium Coxiella burnetii

The agent of Q fever, Coxiella burnetii, is an obligate intracellular bacterium that causes acute and chronic infections. The study of C. burnetii pathogenesis has benefited from two recent fundamental advances: improved genetic tools and the ability to grow the bacterium in extracellular media. In this Review, we describe how these recent advances have improved our understanding of C. burnetii invasion and host cell modulation, including the formation of replication-permissive Coxiella-containing vacuoles. Furthermore, we describe the Dot/Icm (defect in organelle trafficking/intracellular multiplication) system, which is used by C. burnetii to secrete a range of effector proteins into the host cell, and we discuss the role of these effectors in remodelling the host cell.

Infections acquired in intensive care units: results of national surveillance in Belgium, 1997-2010

BACKGROUND AND AIM

To describe the methodology and output of the Belgian surveillance for infections acquired in intensive care units (ICUs) between 1997 and 2010.

METHODS

Since 1997, ICUs in acute care hospitals in Belgium have been encouraged by federal law to participate in a national multi-centre prospective observational surveillance programme. A protocol and software tool for data collection was developed, and the case definitions and methodology follow those of the European Centre for Disease Prevention and Control.

FINDINGS

For 2010, 18 hospitals provided data on 59 observation quarters, 6478 ICU patients and 52,593 ICU patient-days. The mean incidence rates of ICU-acquired pneumonia and intubation-associated pneumonia were 13 per 1000 patient-days and 12 per 1000 intubation-days, respectively. The mean incidence rates of ICU-acquired bloodstream infections, central vascular catheter (CVC)-associated bloodstream infections and CVC-associated primary bloodstream infections were 3.2 per 1000 patient-days, 2.6 per 1000 catheter-days and 2.3 per 1000 catheter-days, respectively. Between 1997 and 2010, stable trends in ICU-acquired pneumonia and bloodstream infections were observed, together with decreasing trends for intubation-associated pneumonia and CVC-associated bloodstream infections, and a stable trend for CVC-associated primary bloodstream infections.

CONCLUSIONS

In Belgium, national surveillance of ICU-acquired infections allows acute care hospitals to track the incidence of infections at local level, enabling comparison with national and European reference data. Between 1997 and 2010, the incidence of ICU-acquired infections increased and the incidence of device-associated infections decreased.

Shear stress is required for the endocytic uptake of the factor VIII-von Willebrand factor complex by macrophages

BACKGROUND

Low-density lipoprotein (LDL) receptor family members contribute to the cellular uptake of factor VIII. How von Willebrand factor fits into this endocytic pathway has remained poorly understood.

OBJECTIVES

It has been suggested that macrophages contribute to the clearance of the factor VIII (FVIII)-von Willebrand factor (VWF) complex. We now assessed the mechanisms of uptake employing human monocyte-derived macrophages.

METHODS

A confocal microscopy study was employed to study the uptake by monocyte-derived macrophages of a functional green fluorescent FVIII-GFP derivative in the presence and absence of VWF.

RESULTS

The results revealed that FVIII-GFP is internalized by macrophages. We found that FVIII-GFP co-localizes with LDL receptor-related protein (LRP), and that the LRP antagonist Receptor Associated Protein (RAP) blocks the uptake of FVIII-GFP. However, FVIII-GFP was not detected in the macrophages in the presence of VWF, suggesting that the FVIII-VWF complex is not internalized by these cells at all. Apart from static conditions, we also investigated the effect of shear stress on the uptake of FVIII-GFP in presence of VWF. Immunofluorescence studies demonstrated that VWF does not block endocytosis of FVIII-GFP under flow conditions. Moreover, VWF itself was also internalized by the macrophages. Strikingly, in the presence of RAP, endocytosis of FVIII-GFP and VWF was inhibited.

CONCLUSION

The results show that shear stress is required for macrophages to internalize both constituents of the FVIII-VWF complex.

Factor seven activating protease (FSAP): does it activate factor VII?

BACKGROUND

Factor seven activating protease (FSAP) was initially reported as an activator of single-chain urokinase-type plasminogen activator (scuPA) and factor VII (FVII). Subsequently, numerous additional substrates have been identified, and multiple other biological effects have been reported. Due to the apparent lack of specificity, the physiological role of FSAP has become increasingly unclear. Rigorous studies have been limited by the difficulty of obtaining intact FSAP from blood or recombinant sources.

OBJECTIVES

Our aim was to produce intact recombinant human FSAP, and to assess its role as a trigger of coagulation and fibrinolysis.

RESULTS

Expression of wild-type FSAP in various mammalian cells invariably resulted in the accumulation of degraded FSAP due to autoactivation and degradation. To overcome this problem, we constructed a variant in which Arg(313) at the natural activation site was replaced by Gln, creating a cleavage site for the bacterial protease thermolysin. HEK293 cells produced FSAP(R313Q) in its intact form. Thermolysin-activated FSAP displayed the same reactivity toward the substrate S-2288 as plasma-derived FSAP, and retained its ability to activate scuPA. Polyphosphate and heparin increased V(max) by 2-3-fold, without affecting K(m) (62 nm) of scuPA activation. Surprisingly, FVII activation by activated FSAP proved negligible, even in the presence of calcium ions, phospholipid vesicles and recombinant soluble tissue factor. On membranes of 100% cardiolipin FVII cleavage did occur, but this resulted in transient activation and rapid degradation.

CONCLUSIONS

While FSAP indeed activates scuPA, FVII appears remarkably resistant to activation. Therefore, reappraisal of the putative role of FSAP in hemostasis seems appropriate.

Characterization of the GDP-D-mannose biosynthesis pathway in Coxiella burnetii: the initial steps for GDP-β-D-virenose biosynthesis

Coxiella burnetii, the etiologic agent of human Q fever, is a Gram-negative and naturally obligate intracellular bacterium. The O-specific polysaccharide chain (O-PS) of the lipopolysaccharide (LPS) of C. burnetii is considered a heteropolymer of the two unusual sugars β-D-virenose and dihydrohydroxystreptose and mannose. We hypothesize that GDP-D-mannose is a metabolic intermediate to GDP-β-D-virenose. GDP-D-mannose is synthesized from fructose-6-phosphate in 3 successive reactions; Isomerization to mannose-6-phosphate catalyzed by a phosphomannose isomerase (PMI), followed by conversion to mannose-1-phosphate mediated by a phosphomannomutase (PMM) and addition of GDP by a GDP-mannose pyrophosphorylase (GMP). GDP-D-mannose is then likely converted to GDP-6-deoxy-D-lyxo-hex-4-ulopyranose (GDP-Sug), a virenose intermediate, by a GDP-mannose-4,6-dehydratase (GMD). To test the validity of this pathway in C. burnetii, three open reading frames (CBU0671, CBU0294 and CBU0689) annotated as bifunctional type II PMI, as PMM or GMD were functionally characterized by complementation of corresponding E. coli mutant strains and in enzymatic assays. CBU0671, failed to complement an Escherichia coli manA (PMM) mutant strain. However, complementation of an E. coli manC (GMP) mutant strain restored capsular polysaccharide biosynthesis. CBU0294 complemented a Pseudomonas aeruginosa algC (GMP) mutant strain and showed phosphoglucomutase activity (PGM) in a pgm E. coli mutant strain. Despite the inability to complement a manA mutant, recombinant C. burnetii PMI protein showed PMM enzymatic activity in biochemical assays. CBU0689 showed dehydratase activity and determined kinetic parameters were consistent with previously reported data from other organisms. These results show the biological function of three C. burnetii LPS biosynthesis enzymes required for the formation of GDP-D-mannose and GDP-Sug. A fundamental understanding of C. burnetii genes that encode PMI, PMM and GMP is critical to fully understand the biosynthesic pathway of GDP-β-D-virenose and LPS structure in C. burnetii.

Metabolic tumour volume. Prognostic value in locally advanced squamous cell carcinoma of the head and neck

PURPOSE

Evaluate the predictive and prognostic value of semi-quantitative FDG-PET variables derived from pretreatment FDG-PET images in patients suffering from locally advanced squamous cell carcinoma of the head and neck (SCCHN), treated by means of concomitant radiochemotherapy.

PATIENTS, METHODS

40 patients with newly diagnosed SCCHN that were treated with concomitant radiochemotherapy underwent FDG-PET/CT for treatment planning; 18 patients had neck dissection prior to their baseline scan and to receiving radiochemotherapy. FDG-PET images were used to calculate metabolic tumour volumes using region growing and a threshold of 50% (MTV50) of primary lesions and involved lymph nodes as well as the mean and maximum standard uptake value (SUVmean and SUVmax) of the primary tumours.

RESULTS

Neither SUVmean nor SUVmax values of the primary tumour were significantly different between responders and non-responders whereas MTV50 values of the primary tumour proved significantly higher in non-responders. SUVmean, SUVmax and MTV50 of the primary tumour were not predictive for overall or disease free survival. Contrariwise, dichotomized summed MTV50 values (cut-off≥31 cm3) of the primary tumour and involved lymph nodes in patients that didn't have neck dissection prior to radiochemotherapy were predictive for disease free and overall survival in both univariate and multivariate analysis (p≤0.05).

CONCLUSION

Summed MTV50 values of both the primary tumour and involved lymph nodes provided independent prognostic information on disease free and overall survival.

Patient-derived monoclonal antibodies directed towards beta2 glycoprotein-1 display lupus anticoagulant activity

BACKGROUND

Patients with antiphospholipid syndrome (APS) display a heterogeneous population of antibodies with beta(2) glycoprotein-1 (β(2)GP1) as the major antigen.

OBJECTIVES

We isolated and characterized human mAbs directed against β(2)GP1 from the immune repertoire of APS patients.

METHODS

Variable heavy chain repertoires from B cells from two APS patients with anti-β(2)GP1 antibodies were cloned into the pHEN1-VLrep vector. Constructed full-length IgG antibodies were tested for lupus anticoagulant (LAC) activity and binding to β(2)GP1 and its domains.

RESULTS

Two clones of each patient were selected on the basis of the reactivity of single chain Fv (scFv) fragments displayed on phages towards full-length β(2)GP1 and its isolated domain I. The affinity of selected antibodies for β(2)GP1 was lost when transforming from phages to monovalent scFvs, and was regained when antibodies were constructed as complete IgG, indicating a role for bivalency in binding to β(2)GP1. Both selected clones from patient 2 recognized domain I of β(2)GP1, and for both clones selected from patient 1, binding required the presence of both domain I and domain II. All mAbs displayed LAC activity in both activated partial thromboplastin time-based and dilute Russell's viper venom test-based clotting assays and in thrombin generation.

CONCLUSIONS

In this study, we show successful cloning of patient-derived mAbs that require domain I of β(2)GP1 for binding, and that display LAC activity that is dependent on their affinity for β(2)GP1. These antibodies can help us to gain more insights into the pathogenesis of APS, and may facilitate standardization of APS diagnosis.

The assessment of viscosity measurements on the albumen of consumption eggs as an indicator for freshness

Viscosity values of albumen reported in the literature are difficult to compare because different shear rates and different methods of sample preparation have been adopted. Therefore, we first investigated the effect of shear rate on the viscosity measurements of thick albumen. For intact albumen, a large intersample fluctuation in viscosity with increasing shear rate was observed. Furthermore, a large hysteresis effect was observed, indicating that the structural properties were substantially altered by the rotational behavior of the rotor. From this, we concluded that to obtain reliable measurements, the albumen needed to be mixed. After mixing, a smooth evolution in viscosity with increasing shear rate was observed. Compared with intact albumen, the hysteresis effect was smaller but still present. We next investigated the correlation between albumen viscosity and Haugh units. For this, we compared the viscosity of fresh eggs with the viscosity of eggs stored for 24 d at a temperature of 18°C. The Haugh units were first determined, and the viscosity was next determined on mixed albumen at a shear rate of 200 rad/s. Mean viscosity equaled 0.0304 and 0.0181 Pa/s for fresh eggs and eggs stored for 24 d, respectively. The decrease in viscosity during storage was significant (α = 0.05). Furthermore, we observed that the correlation between Haugh units and viscosity measured on the same egg was low. Fresh eggs having comparable Haugh units differed substantially in their measured viscosities, whereas for stored eggs, the Haugh units differed substantially but the viscosities were comparable. It is unlikely that the very large variation in rheological properties observed among fresh eggs reflects the natural variation in albumen freshness present after lay. Results suggest that these differences were partly due to the structural changes caused by albumen sampling and by the turning motion of the rotor. We conclude that determination of the rheological properties of albumen is practically infeasible and that albumen viscosity cannot be used as an index for albumen freshness.

New approach of testing the effect of heat stress on eggshell quality: mechanical and material properties of eggshell and membrane

1. The effect of high temperature on eggshell quality was investigated by measuring the mechanical and material properties of shell and membranes. 2. Heat exposure resulted in a decrease in zootechnical performance and eggshell thickness, increase in egg breakage, and unchanged egg shape index. 3. The static stiffness (Kstat), dynamic stiffness (Kdyn) and modulus of elasticity of the eggshell were not significantly affected by high temperature. Membrane prolongation increased significantly while membrane attachment strength and breakage strength tended to decrease and increase, respectively. The relationships between these variables were changed by high temperature. 4. Neither Kstat nor Kdyn could give a reasonable explanation for the changed eggshell quality induced by heat stress. The decreased eggshell thickness and changed properties of shell membrane may be responsible, at least partially, for the decreased shell quality of eggs from heat-stressed hens.

Antiserum against Raoultella terrigena ATCC 33257 identifies a large number of Raoultella and Klebsiella clinical isolates as serotype O12

Raoultella terrigena ATCC 33257, recently reclassified from the genus Klebsiella, is a drinking water isolate and belongs to a large group of non-typeable Klebsiella and Raoultella strains. Using an O-antiserum against a capsule-deficient mutant of this strain, we could show a high prevalence (10.5%) of the R. terrigena O-serotype among non-typeable, clinical Klebsiella and Raoultella isolates. We observed a strong serological cross-reaction with the K. pneumoniae O12 reference strain, indicating that a large percentage of these non-typeable strains may belong to the O12 serotype, although these are currently not detectable by the K. pneumoniae O12 reference antiserum in use. Therefore, we analyzed the O-polysaccharide (O-PS) structure and genetic organization of the wb gene cluster of R. terrigena ATCC 33257, and both confirmed a close relation of R. terrigena and K. pneumoniae O12. The two strains possess an identical O-PS, lipopolysaccharide core structure, and genetic organization of the wb gene cluster. Heterologous expression of the R. terrigena wb gene cluster in Escherichia coli K-12 resulted in the WecA-dependent synthesis of an O-PS reactive with the K. pneumoniae O12 antiserum. The serological data presented here suggest a higher prevalence of the O12-serotype among Klebsiella and Raoultella isolates than generally assumed.

The association between circulating antibodies against domain I of beta2-glycoprotein I and thrombosis: an international multicenter study

BACKGROUND

Diagnosis of the antiphospholipid syndrome (APS) is difficult as a result of limited specificity of existing assays for detecting clinically relevant antiphospholipid antibodies. Anti-beta2-glycoprotein I (beta 2GPI) antibodies play a central role in the disease process of APS.

OBJECTIVES

We have investigated the relation between antiphospholipid antibodies with specificity for domain I of beta 2GPI and thrombosis/pregnancy morbidity in an international multicenter study.

PATIENTS/METHODS

Four hundred and seventy-seven patients derived from nine different centres met the inclusion criterion of having anti-beta 2GPI antibodies in their plasma/serum. Clinical data and results of tests for lupus anticoagulant, anti-cardiolipin antibodies and anti-beta 2GPI antibodies were established at the different centres of inclusion. After being re-tested for the presence of IgG and/or IgM anti-beta 2GPI antibodies, the samples were tested for the presence of IgG-directed against domain I of beta 2GPI and results were correlated with the thrombotic and obstetric history.

RESULTS

Re-testing for the presence of anti-beta 2GPI antibodies resulted in inclusion of 442/477 patients. IgG class anti-domain I antibodies were present in plasma of 243/442 patients (55%). 201/243 (83%) had a history of thrombosis. This resulted in an odds ratio of 3.5 (2.3-5.4, 95% confidence interval) for thrombosis. Anti-domain I IgG antibodies were also significantly correlated with obstetric complications [odds ratio: 2.4 (1.4-4.3, 95% confidence interval)].

CONCLUSION

In this multicenter study, the detection of IgG antibodies that are directed against domain I of beta 2GPI proved to be more strongly associated with thrombosis and obstetric complications than those detected using the standard anti-beta 2GPI antibody assay.

External quality assessment in the measurement of haemoglobin by blood gas analysers in Belgium

OBJECTIVE

The Belgian national External Quality Assessment Scheme (EQAS) for haematology organized a survey to assess the reliability of haemoglobin (Hb) measurements with the blood gas analysers (BGAs) currently available in Belgian hospitals.

MATERIAL AND METHODS

All hospital laboratories received two specimens of fresh EDTA anticoagulated whole blood and were asked to determine the Hb concentration using both the conventional haematology analyser (HA) and all BGAs in the hospital. Ninety-seven hospital laboratories participated in the study and a total of 166 results were reported. The BGAs used (grouped according to technology) were Rapidlab 845, 855, 865 (Bayer 1, n = 41), Rapidlab 1245, 1265, Rapidpoint 405 (Bayer 2, n = 19), GEM Premier 3000 (Instrumentation Laboratory, IL, n = 13), ABL 500 and 600 series (Radiometer 1, n = 13), ABL 700 and 800 series (Radiometer 2, n = 35), Omni C, S5 (Roche 1, n = 7), Omni 3, 6, 9, S2, S4, S6 (Roche 2, n = 21).

RESULTS

For the BGAs from Bayer, Radiometer and Roche, interlaboratory variation ranged from 0.6 % to 4.1 %, indicating good precision and close agreement between centres. A significant negative bias observed on the GEM Premier 3000 using the EDTA anticoagulated blood samples did not appear to be present in fresh heparinized whole blood samples. There was no significant difference in imprecision and bias between Hb measurements on BGA situated in and outside the central laboratory.

Nation-wide prospective surveillance of Clostridium difficile infections in hospitals in Belgium, July 2007-June 2008

We report here baseline data from the first year of compulsory surveillance of Clostridium difficile infections (CDI) in hospitals in Belgium. Between 1 July 2007 and 30 June 2008, 2,704 CDI were reported: 12% were recurrent and 66% were hospital-associated (half of which occurred 15 days or more after admission). CDI was considered the cause of death (direct or indirect) for 10% of the episodes. The median incidence of CDI was 1.5 per 1,000 admissions and 1.9 per 10,000 hospital-days for all cases, and 0.9 per 1,000 admissions, and 1.1 per 10,000 hospital-days for hospital-associated cases. Further investigation of risk stratification by average length of stay in the reporting hospitals is warranted as a way to improve the comparability of indicators across hospitals and surveillance systems. In spite of methodological issues, the surveillance of CDI in Belgian hospitals has been able to produce robust baseline data that should allow monitoring of trends at hospital and national level, and provide a basis for international comparisons. Remaining challenges are to define and monitor targets for the control of CDI, and to improve the individual feed-back of data at hospital level.

Nation-wide prospective surveillance of Clostridium difficile infections in hospitals in Belgium, July 2007-June 2008

We report here baseline data from the first year of compulsory surveillance of Clostridium difficile infections (CDI) in hospitals in Belgium. Between 1 July 2007 and 30 June 2008, 2,704 CDI were reported: 12% were recurrent and 66% were hospital-associated (half of which occurred 15 days or more after admission). CDI was considered the cause of death (direct or indirect) for 10% of the episodes. The median incidence of CDI was 1.5 per 1,000 admissions and 1.9 per 10,000 hospital-days for all cases, and 0.9 per 1,000 admissions, and 1.1 per 10,000 hospital-days for hospital-associated cases. Further investigation of risk stratification by average length of stay in the reporting hospitals is warranted as a way to improve the comparability of indicators across hospitals and surveillance systems. In spite of methodological issues, the surveillance of CDI in Belgian hospitals has been able to produce robust baseline data that should allow monitoring of trends at hospital and national level, and provide a basis for international comparisons. Remaining challenges are to define and monitor targets for the control of CDI, and to improve the individual feed-back of data at hospital level.

Constitutive SOS expression and damage-inducible AddAB-mediated recombinational repair systems for Coxiella burnetii as potential adaptations for survival within macrophages

SUMMARY

Coxiella burnetii, a Gram-negative obligate intracellular pathogen, replicates within an parasitophorous vacuole with lysosomal characteristics. To understand how C. burnetii maintains genomic integrity in this environment, a database search for genes involved in DNA repair was performed. Major components of repair, SOS response and recombination were identified, including recA and ruvABC, but lexA and recBCD were absent. Instead, C. burnetii possesses addAB orthologous genes, functional equivalents to recBCD. Survival after treatment with UV, mitomycin C (MC) or methyl methanesulfonate (MMS), as well as homologous recombination in Hfr mating was restored in Escherichia coli deletion strains by C. burnetii recA or addAB. Despite the absence of LexA, co-protease activity for C. burnetii RecA was demonstrated. Dominant-negative inhibition of C. burnetii RecA by recA mutant alleles, modelled after E. coli recA1 and recA56, was observed and more apparent with expression of C. burnetii RecAG159D mutant protein. Expression of a subset of repair genes in C. burnetii was monitored and, in contrast to the non-inducible E. coli recBCD, addAB expression was strongly upregulated under oxidative stress. Constitutive SOS gene expression due to the lack of LexA and induction of AddAB likely reflect a unique repair adaptation of C. burnetii to its hostile niche.

Efficiency of von Willebrand factor-mediated targeting of interleukin-8 into Weibel-Palade bodies

BACKGROUND

After de novo synthesis in endothelial cells, the chemokine interleukin-8 (IL-8) is targeted to endothelial cell-specific storage vesicles, the Weibel-Palade bodies (WPBs), where it colocalizes with von Willebrand factor (VWF).

OBJECTIVE

In this study we investigated a putative regulator function for VWF in the recruitment of IL-8 to WPBs.

METHODS

We performed a quantitative analysis of the entry of IL-8 into the storage system of the endothelium using pulse-chase analysis and subcellular fractionation studies.

RESULTS

Using pulse-chase analysis of IL-1beta-stimulated human umbilical vein endothelial cells, we found that a small part of de novo synthesized IL-8 was retained in endothelial cells after 4 h. In density gradients of endothelial cell homogenates nearly equimolar amounts of VWF and IL-8 were present in subcellular fractions that contained WPBs. Furthermore, we found that IL-8 binds to immobilized VWF under the slightly acidic conditions thought to prevail in the lumen of the late secretory pathway.

CONCLUSIONS

These observations indicate that the sorting efficiency of IL-8 into the regulated secretory pathway of the endothelium is tightly controlled by the entry of VWF into WPBs.

Requirements for cellular co-trafficking of factor VIII and von Willebrand factor to Weibel-Palade bodies

BACKGROUND

von Willebrand factor (VWF) serves a critical role as a carrier of factor (F)VIII in circulation. While it is generally believed that FVIII and VWF assemble in circulation after secretion from different cells, an alternative view is that cells should exist that co-express FVIII and VWF.

OBJECTIVES

In this study, intracellular co-expression of FVIII and VWF was studied, with particular reference to complex assembly and high-affinity interaction.

METHODS

Using yellow fluorescent protein-tagged FVIII (FVIII-YFP) and cyan fluorescent protein-tagged VWF (VWF-CFP), we studied intracellular trafficking in human embryonic kidney (HEK293) cells and human umbilical vein endothelial cells (HUVEC). The role of the high-affinity interaction between FVIII and VWF was assessed using a FVIII-YFP variant carrying a Tyr1680Phe substitution, which abolishes high-affinity binding to VWF. Cellular trafficking studies were complemented by binding studies employing purified proteins.

RESULTS

Solid phase binding assays employing FVIII-YFP demonstrated that the presence of the fluorescent moiety did not compromise high-affinity binding (K(d) = 0.065 +/- 0.008 nm) whereas the binding of the Tyr1680Phe FVIII-YFP variant was significantly reduced. Co-expression studies in HEK293 cells revealed intracellular co-storage of both FVIII-YFP and Tyr1680Phe FVIII-YFP within VWF-containing storage organelles. In addition, expression of FVIII-YFP and Tyr1680Phe FVIII-YFP in HUVEC demonstrated co-trafficking with endogenous VWF to authentic Weibel-Palade bodies (WPBs).

CONCLUSIONS

Our findings demonstrate that FVIII trafficking to WPBs is independent of Tyr1680 and high-affinity binding to VWF. We therefore conclude that the structural requirements that determine intracellular co-trafficking differ from those that determine complex assembly in circulation.