Genetic resistance determinants to fusidic acid and chlorhexidine in variably susceptible staphylococci from dogs

BACKGROUND

Concern exists that frequent use of topically-applied fusidic acid (FA) and chlorhexidine (CHX) for canine pyoderma is driving clinically relevant resistance, despite rare description of FA and CHX genetic resistance determinants in canine-derived staphylococci. This study aimed to determine minimum inhibitory concentrations (MICs) and investigate presence of putative resistance determinants for FA and CHX in canine-derived methicillin-resistant (MR) and -susceptible (MS) staphylococci. Plasmid-mediated resistance genes (fusB, fusC, fusD, qacA/B, smr; PCR) and MICs (agar dilution) of FA and CHX were investigated in 578 staphylococci (50 MR S. aureus [SA], 50 MSSA, 259 MR S. pseudintermedius [SP], 219 MSSP) from Finland, U.S.A., North (NUK) and South-East U.K. (SEUK) and Germany. In all isolates with FA MIC ≥64 mg/L (n = 27) fusA and fusE were amplified and sequenced.

RESULTS

FA resistance determinants (fusA mutations n = 24, fusB n = 2, fusC n = 36) were found in isolates from all countries bar U.S.A. and correlated with higher MICs (≥1 mg/L), although 4 SP isolates had MICs of 0.06 mg/L despite carrying fusC. CHX MICs did not correlate with qacA/B (n = 2) and smr (n = 5), which were found in SEUK SA, and SP from NUK and U.S.A.

CONCLUSIONS

Increased FA MICs were frequently associated with fusA mutations and fusC, and this is the first account of fusB in SP. Despite novel description of qacA/B in SP, gene presence did not correlate with CHX MIC. Selection pressure from clinical use might increase prevalence of these genetic determinants, but clinical significance remains uncertain in relation to high skin concentrations achieved by topical therapy.

Analysis of the 3D microstructure of experimental cathode films for lithium-ion batteries under increasing compaction

It is well known that the microstructure of electrodes in lithium-ion batteries has an immense impact on their overall performance. The compaction load during the calendering process mainly determines the resulting morphology of the electrode. Therefore, NCM-based cathode films from uncompacted (0 MPa) to most highly compacted (1000 MPa) were manufactured, which corresponds to global porosities ranging from about 50% to 18%. All samples have been imaged using synchrotron tomography. These image data allow an extensive analysis of the 3D cathode microstructure with respect to increasing compaction. In addition, the numerous microstructural changes can be quantified using several characteristics describing the morphology of cathode samples. Three characteristics, namely global porosity, global volume fraction of active material and mean cathode thickness, are compared to experimental results. In addition, the microstructural analysis by means of 3D image data and image processing techniques allows the investigation of characteristics which are hard or impossible to ascertain by experiments, for example the continuous pore size distribution and the sphericity distribution of NCM-particles. Finally, the dependency of microstructural characteristics on compaction load is described by the help of parametric probability distributions. This approach can be used, for example, to predict the distribution of a certain characteristic for an 'unknown' compaction load, which is a valuable information with regard to the optimization and development process of NCM-cathodes in lithium-ion batteries.

LAY DESCRIPTION

It is well known that the microstructure of electrodes in lithium-ion batteries has an immense impact on their overall performance. The manufacturing of the batteries includes the so-called calendering, where the electrodes are compressed with a certain pressure, which is called compaction load. This process step mainly determines the resulting morphology of the electrode and thus the properties of the battery. Therefore, eight cathodes with different compaction loads were manufactured and imaged by synchrotron tomography, which leads to 3D images containing detailed information about the inner structure of the cathode. This image data allows an extensive analysis of the 3D cathode microstructure with respect to increasing compaction. In order to quantify the microstructural changes we use several characteristics describing diverse properties of the morphology. Furthermore, the 3D image data can be used for the computation of characteristics which can not be determined by experiments. Therefore, 3D image data allows us to understand how the microstructure of cathodes is influenced by the compaction load. Finally, we are able to predict the distribution of a certain characteristic for arbitrary compaction loads. This information is valuable with regard to the development of improved lithium-ion batteries.

Pore space extraction and characterization of sack paper using μ-CT

We show that attenuation X-ray microcomputed tomography (μ-CT) offers a route to extract the three-dimensional pore space of paper reliably enough to distinguish samples of the same kind of paper. Here, we consider two sack kraft papers for cement bags with different basis weights and thicknesses. Sample areas of approximately 5 mm² with a resolution of 1.5 μm are considered, i.e. sizes that exceed sample areas of 2 mm² for which the pore structure was previously studied in the literature. The image segmentation is based on indicator kriging as a local method that removes ambiguities in assigning voxels as pore or as fibre. The microstructures of the two samples are statistically compared in terms of descriptors such as sheet thickness, porosity, fractions of externally accessible pores and mean geodesic tortuosity. We demonstrate that a quantitative comparison of samples in terms of porosity and thickness requires a common definition of the sheet surfaces. Finally, the statistical pore space analysis based on the μ-CT scans reliably reveals structural differences between the two paper samples, but only when several descriptors are used.

LAY DESCRIPTION

This paper is a seemingly abundant material. Its intrinsic porosity enables a vast number of commercial applications. Particularly packing products, e.g. cement bags, often incorporate sack kraft paper due to its high porosity and its additional mechanical strength. A direct quantification of the porosity of sack kraft papers is, hence, particularly desirable. However, experimental quantification of paper porosity or its pore network properties is difficult and often highly indirect. A nondestructive statistical analysis of the 3D microstructure holds the promise to directly assess the pores. In particular, X-ray microcomputed tomography (μ-CT), frequently with sub-μm resolution, has been established as a method to study the fibre and pore structure of paper. The question arises, whether statistical analysis of the microstructure based on μ-CT imaging is sufficient to reliably distinguish between different sack kraft papers. Here, we explore whether the pore structure of paper can be extracted and statistically analysed for larger sample areas despite the fact that a larger sample size directly translates into a lower resolution of the μ-CT scan. We expect that a large sample size increases the region of interest on the basis of which samples can be better distinguished. A lowered resolution poses a severe challenge for the reliable identification of voxel data as pores or as fibres, because the contrast between paper fibres (made of cellulose) and air, which is established due to X-ray absorption, is weak. We show that we can reliably assign each voxel by using an indicator kriging as a two-step method. This method performs an initial voxel identification based on the overall distribution of measured grey values and refines the identification by inspecting the local environment of each voxel. For the pore space extracted in such a way, we can then compute quantities that are related to the geometry and connectivity properties of the pores. Furthermore, we address a paper-born challenge for such an analysis, i.e. we cannot always unambiguously tell whether a pore is located inside the paper sheet or at the surface of the paper. The way the paper surfaces are extracted from the microstructure decisively determines the final specifications of the predicted properties. A significant distinction of the samples is only possible when comparing the properties of the pore network.

Wirksamkeit von Doxycyclin bei Chlamydiosen in Taubenbeständen

Gegenstand und Ziel: Untersuchung der klinischen Wirksamkeit von über das Trinkwasser verabreichtem Doxycyclin zur Behandlung der Chlamydiose bei Briefund Rassetauben (Columba livia f. domestica) in infizierten, klinisch erkrankten Beständen unter Praxisbedingungen. Material und Methoden: Im Rahmen einer kontrollierten Feldstudie zur klinischen Wirksamkeit wurden 13 Taubenbestände mit klinisch manifester Ornithose über 25 Tage mit einer neuartigen Formulierung von Doxycyclin über das Trinkwasser behandelt. In jedem der Bestände war die Infektion mit Chlamydia psittaci zuvor anhand molekularbiologischer Untersuchung von Organmaterial zur pathologischen Untersuchung eingesandter Tiere festgestellt worden. Zur Überprüfung des Therapieerfolgs wurden am 25. Tag der Behandlung und 7 Tage nach Abschluss der Therapie Dreifachtupfer von 10 Tieren jedes Bestandes genommen und mittels PCR untersucht. Ferner fanden wiederholt Einzeltier- und täglich Herdenuntersuchungen in den Beständen statt. Ergebnisse: Der Erreger Chlamydia psittaci sowie andere, in sechs der 13 Bestände zusätzlich dokumentierte atypische Chlamydienspezies ließen sich bei den genannten Untersuchungen nicht mehr nachweisen. Zudem wurde in jedem Bestand ein Verschwinden der klinischen Krankheitssymptomatik erreicht. Schlussfolgerung: Die Anwendung von Doxycyclin im beschriebenen Therapieregime erwies sich als wirksam zur Behandlung der Ornithose. Darüber hinaus konnte eine hervorragende Akzeptanz und Verträglichkeit der eingesetzten Formulierung in praxi bestätigt werden.

Tierärztliche Betreuung von Taubenbeständen

Die tierärztliche Behandlung und Betreuung von Taubenbeständen bedarf spezifischen Wissens sowohl über die Haltung von Tauben bzw. die Gegebenheiten eines Taubenbestandes als auch über häufige Krankheiten und wichtige diagnostische sowie therapeutische Maßnahmen. Bedeutung hat in diesem Kontext die Unterscheidung zwischen Rasse-, Fleisch- und Brieftauben, also lebensmittelliefernden oder nicht lebensmittelliefernden Tieren. Der Beitrag gibt eine Übersicht über zu berücksichtigende Besonderheiten der Spezies Taube, häufig vorkommende Erkrankungen sowie gängige therapeutische und prophylaktische Maßnahmen.

Dimerization leads to changes in APP (amyloid precursor protein) trafficking mediated by LRP1 and SorLA

Proteolytic cleavage of the amyloid precursor protein (APP) by α-, β- and γ-secretases is a determining factor in Alzheimer's disease (AD). Imbalances in the activity of all three enzymes can result in alterations towards pathogenic Aβ production. Proteolysis of APP is strongly linked to its subcellular localization as the secretases involved are distributed in different cellular compartments. APP has been shown to dimerize in cis-orientation, affecting Aβ production. This might be explained by different substrate properties defined by the APP oligomerization state or alternatively by altered APP monomer/dimer localization. We investigated the latter hypothesis using two different APP dimerization systems in HeLa cells. Dimerization caused a decreased localization of APP to the Golgi and at the plasma membrane, whereas the levels in the ER and in endosomes were increased. Furthermore, we observed via live cell imaging and biochemical analyses that APP dimerization affects its interaction with LRP1 and SorLA, suggesting that APP dimerization modulates its interplay with sorting molecules and in turn its localization and processing. Thus, pharmacological approaches targeting APP oligomerization properties might open novel strategies for treatment of AD.

Phase Locking the Spin Precession in a Storage Ring

This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97  GeV/c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (≈121  kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a 1 standard deviation range of σ=0.21  rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26  mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.

Present status of laboratory diagnosis of human taeniosis/cysticercosis in Europe

Human cysticercosis (CC) is a parasitic zoonosis caused by the larval stage (cyst) of the Taenia solium. Cysts can establish in the human central nervous system (neurocysticercosis, NCC) and other organs and tissues; they also develop in pigs, the natural intermediate host. Human taeniosis may be caused by T. solium, Taenia saginata and Taenia asiatica tapeworms; these infections are usually asymptomatic, but show a significant relevance as they perpetuate the parasites’ life cycle, and, in the case of T. solium, they are the origin of (N)CC. In European Union (EU) member states and associated countries, the occurrence of autochthonous T. solium cases is debated, and imported cases have significantly increased lately; the status of T. asiatica has been never reported, whereas T. saginata is prevalent and causes an economic impact due to condemned carcasses. Based on their effects on the EU society, the specific diagnosis of these pathologies is relevant for their prevention and control. The aims of this study were to know the diagnostic tests used in European laboratories for human taeniosis/cysticercosis by means of a questionnaire, to determine potential gaps in their detection, and to obtain preliminary data on the number of diagnosed taeniosis/CC cases.

Morphology and Morphometry of the Lung in Corn Snakes (Pantherophis guttatus) Infected with Three Different Strains of Ferlavirus

Ophidian paramyxovirus (ferlavirus) is a global threat to reptilian sauropsids in herpetological collections, with occasional but fatal effects. This study characterizes the effects of three different genetic strains of ferlavirus on the dynamic changes of histology and morphometry of the lung of corn snakes (Pantherophis guttatus). Lungs from 42 corn snakes were either sham-infected or infected experimentally under standardized conditions. From 4 to 49 days after intratracheal inoculation, the lungs were examined qualitatively and quantitatively. Progressive microscopical changes were seen in the lung. Initially, increased numbers of heterophils were observed in the interstitium followed by proliferation and vacuolation of epithelial cells lining faveoli. Electron microscopy revealed loss of type-I pneumocytes, hyperplasia of type-II pneumocytes, and interstitial infiltrates of heterophils and mononuclear cells. With progression of disease the respiratory epithelium was initially overgrown by transformed type-II pneumocytes and later became multilayered. The results of the study suggest that the respiratory capacity of the lungs declines with disease development. The dynamics of disease development and histopathology differed in snakes infected with different ferlavirus genogroups. Animals infected with virus genogroup B developed histopathological changes and morphometric changes more rapidly and of greater intensity than snakes infected with viruses from genogroups A or C.

Imbedded and non-imbedded stationary characteristics of queueing systems with varying service rate and point processes

In this paper a unified approach is used for proving relationships between customer-stationary and time-stationary characteristics of service systems with varying service rate and point processes. This approach is based on an intensity conservation principle for general stationary continuous-time processes with imbedded stationary marked point processes. It enables us to work under weaker independence assumptions than usual in queueing theory.

Stochastic inequalities between customer-stationary and time-stationary characteristics of queueing systems with point processes

By means of a general intensity conservation principle for stationary processes with imbedded marked point processes (PMP) stochastic inequalities are proved between customer-stationary and time-stationary characteristics of queueing systems G/G/s/r.

First Passage Percolation on Random Geometric Graphs and an Application to Shortest-Path Trees

We consider Euclidean first passage percolation on a large family of connected random geometric graphs in the d-dimensional Euclidean space encompassing various well-known models from stochastic geometry. In particular, we establish a strong linear growth property for shortest-path lengths on random geometric graphs which are generated by point processes. We consider the event that the growth of shortest-path lengths between two (end) points of the path does not admit a linear upper bound. Our linear growth property implies that the probability of this event tends to zero sub-exponentially fast if the direct (Euclidean) distance between the endpoints tends to infinity. Besides, for a wide class of stationary and isotropic random geometric graphs, our linear growth property implies a shape theorem for the Euclidean first passage model defined by such random geometric graphs. Finally, this shape theorem can be used to investigate a problem which is considered in structural analysis of fixed-access telecommunication networks, where we determine the limiting distribution of the length of the longest branch in the shortest-path tree extracted from a typical segment system if the intensity of network stations converges to 0.

Connectivity of Random Geometric Graphs Related to Minimal Spanning Forests

The almost-sure connectivity of the Euclidean minimal spanning forest MSF(X) on a homogeneous Poisson point process X ⊂ ℝd is an open problem for dimension d>2. We introduce a descending family of graphs (Gn)n≥2 that can be seen as approximations to the MSF in the sense that MSF(X)=∩n=2∞Gn(X). For n=2, one recovers the relative neighborhood graph or, in other words, the β-skeleton with β=2. We show that almost-sure connectivity of Gn(X) holds for all n≥2, all dimensions d≥2, and also point processes X more general than the homogeneous Poisson point process. In particular, we show that almost-sure connectivity holds if certain continuum percolation thresholds are strictly positive or, more generally, if almost surely X does not admit generalized descending chains.

Reference instruments based on spectrometric measurement with Lucas Cells

The Bundesamt für Strahlenschutz (Berlin, Germany) and the Paul Scherrer Institute (Villigen, Switzerland) both operate accredited calibration laboratories for radon gas activity concentration. Both the institutions use Lucas Cells as detector in their reference instrumentation due to the low dependence of this detector type on variations in environmental conditions. As a further measure to improve the quality of the reference activity concentration, a spectrometric method of data evaluation has been applied. The electric pulses from the photomultiplier tube coupled to the Lucas Cells are subjected to a pulse height analysis. The stored pulse height spectra are analysed retrospectively to compensate for fluctuations in the electric parameters of the instrumentation during a measurement. The reference instrumentation of both the laboratories is described with the respective spectrum evaluation procedures. The methods of obtaining traceability to the primary calibration laboratories of Germany and Switzerland and data of performance tests are presented.

A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers

We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell.

Taenia solium metacestode preparation in rural areas of sub-Saharan Africa: a source for diagnosis and research on cysticercosis

BACKGROUND

Taenia solium metacestodes/cysts obtained from pig carcasses constitute a primary source for diagnostic tools used for the detection of human cysticercosis. Data on T. solium cyst preparation in Africa is still scarce but required to establish independent reference laboratories.

OBJECTIVES

The aim of the present study is a) to present the likely yield of T. solium cyst material by the use of two different preparation methods in the field and b) to investigate its suitability for immunodiagnosis of human cysticercosis.

METHODS

In Zambia, Uganda and Tanzania 670 pigs were screened for T. solium infection. Cysts were prepared by 'shaking method' and 'washing method'. Generated crude antigens were applied in a standard western blot assay.

RESULTS

46 out of 670 pigs (6.9%) were found positive for T. solium (Zambia: 12/367, 3.3%; Uganda: 11/217, 5.1%; Tanzania 23/86, 26.7%). Mean values of 77.7 ml whole cysts, 61.8 ml scolices/membranes and 10.9 ml cyst fluid were obtained per pig. Suitability of collected material for the use as crude antigen and molecular diagnostic techniques was demonstrated.

CONCLUSION

This study clearly shows that T. solium cyst preparation in African settings by simple field methods constitutes an effective way to obtain high quality material as source for diagnostic tools and research purposes.