Structural and electro-anatomical characterization of the equine pulmonary veins: implications for atrial fibrillation.

INTRODUCTION/OBJECTIVES: Spontaneous pulmonary vein (PV) activity triggers atrial fibrillation (AF) in humans. Although AF frequently occurs in horses, the origin remains unknown. This study investigated the structural and electro-anatomical properties of equine PVs to determine the potential presence of an arrhythmogenic substrate. ANIMALS, MATERIALS AND METHODS: Endocardial three-dimensional electro-anatomical mapping (EnSite Precision) using high-density (HD) catheters was performed in 13 sedated horses in sinus rhythm. Left atrium (LA) access was obtained retrogradely through the carotid artery. Post-mortem, tissue was harvested from the LA, right atrium (RA), and PVs for histological characterization and quantification of ion channel expression using immunohistochemical analysis. RESULTS: Geometry, activation maps, and voltage maps of the PVs were created and a median of four ostia were identified. Areas of reduced conduction were found at the veno-atrial junction. The mean myocardial sleeve length varied from 28 ± 13 to 49 ± 22 mm. The PV voltage was 1.2 ± 1.4 mV and lower than the LA (3.4 ± 0.9 mV, P < 0.001). The fibrosis percentage was higher in PV myocardium (26.1 ± 6.6%) than LA (14.5 ± 5.0%, P = 0.003). L-type calcium channel (CaV1.2) expression was higher in PVs than LA (P = 0.001). T-type calcium channels (CaV3.3), connexin-43, ryanodine receptor-2, and small conductance calcium-activated potassium channel-3 was expressed in PVs. CONCLUSIONS: The veno-atrial junction had lower voltages, increased structural heterogeneity and areas of slower conduction. Myocardial sleeves had variable lengths, and a different ion channel expression compared to the atria. Heterogeneous properties of the PVs interacting with the adjacent LA likely provide the milieu for re-entry and AF initiation.

Local-scale Arctic tundra heterogeneity affects regional-scale carbon dynamics.

In northern Alaska nearly 65% of the terrestrial surface is composed of polygonal ground, where geomorphic tundra landforms disproportionately influence carbon and nutrient cycling over fine spatial scales. Process-based biogeochemical models used for local to Pan-Arctic projections of ecological responses to climate change typically operate at coarse-scales (1km2-0.5°) at which fine-scale (<1km2) tundra heterogeneity is often aggregated to the dominant land cover unit. Here, we evaluate the importance of tundra heterogeneity for representing soil carbon dynamics at fine to coarse spatial scales. We leveraged the legacy of data collected near Utqiagvik, Alaska between 1973 and 2016 for model initiation, parameterization, and validation. Simulation uncertainty increased with a reduced representation of tundra heterogeneity and coarsening of spatial scale. Hierarchical cluster analysis of an ensemble of 21st-century simulations reveals that a minimum of two tundra landforms (dry and wet) and a maximum of 4km2 spatial scale is necessary for minimizing uncertainties (<10%) in regional to Pan-Arctic modeling applications.

Traditional plant functional groups explain variation in economic but not size-related traits across the tundra biome.

AIM: Plant functional groups are widely used in community ecology and earth system modelling to describe trait variation within and across plant communities. However, this approach rests on the assumption that functional groups explain a large proportion of trait variation among species. We test whether four commonly used plant functional groups represent variation in six ecologically important plant traits. LOCATION: Tundra biome. TIME PERIOD: Data collected between 1964 and 2016. MAJOR TAXA STUDIED: 295 tundra vascular plant species. METHODS: We compiled a database of six plant traits (plant height, leaf area, specific leaf area, leaf dry matter content, leaf nitrogen, seed mass) for tundra species. We examined the variation in species-level trait expression explained by four traditional functional groups (evergreen shrubs, deciduous shrubs, graminoids, forbs), and whether variation explained was dependent upon the traits included in analysis. We further compared the explanatory power and species composition of functional groups to alternative classifications generated using post hoc clustering of species-level traits. RESULTS: Traditional functional groups explained significant differences in trait expression, particularly amongst traits associated with resource economics, which were consistent across sites and at the biome scale. However, functional groups explained 19% of overall trait variation and poorly represented differences in traits associated with plant size. Post hoc classification of species did not correspond well with traditional functional groups, and explained twice as much variation in species-level trait expression. MAIN CONCLUSIONS: Traditional functional groups only coarsely represent variation in well-measured traits within tundra plant communities, and better explain resource economic traits than size-related traits. We recommend caution when using functional group approaches to predict tundra vegetation change, or ecosystem functions relating to plant size, such as albedo or carbon storage. We argue that alternative classifications or direct use of specific plant traits could provide new insights for ecological prediction and modelling.

Systematic account of animal poisonings in Germany, 2012-2015.

A systematic retrospective study on animal poisonings in Germany (wildlife excluded) between January 2012 and December 2015 was conducted. Data were collected on animal exposure calls to German poison centres, poisoning cases presenting to the University of Veterinary Medicine, Hannover Small Animal and Equine Clinics, cases involving off-label use of veterinary medicinal products reported to the Federal Office of Consumer Protection and Food Safety and toxicological submissions to the Institute of Pharmacology, Toxicology, and Pharmacy, Faculty of Veterinary Medicine, Ludwig-Maximilians-University, Munich. Descriptive statistics were used to characterise animal type, exposure reason, type and substance, year/month of exposure, case severity and outcome. An evaluation of the data and data sources was also carried out. Variation in poisoning patterns was seen. However, dogs and cats were the most frequently reported species and medicinal products, pesticides and plants were consistently implicated as top causes of poisoning. Advantages and disadvantages were associated with each data source; bias was found to be an important consideration when evaluating poisoning data. This study provided useful information on animal poisonings in Germany and highlights the need for standardised approaches for the collection, evaluation and integration of poisoning data from multiple sources.

Histopathological changes and mRNA expression in lungs of horses after inhalation anaesthesia with different ventilation strategies.

Inappropriate mechanical ventilation can lead to ventilator-induced lung injury (VILI). Aim of this study was to evaluate the effects of inhalation anaesthesia and ventilation with and without recruitment (RM) and PEEP titration on alveolar integrity in horses. Twenty-three horses were divided into 4 groups (group OLC ventilated with OLC, group IPPV ventilated with intermittent positive pressure ventilation, group NV non-ventilated, and group C non-anaesthetized control group). After sedation with xylazine and induction with diazepam and ketamine anaesthetized horses were under isoflurane anaesthesia for 5.5h. The horses were euthanized and tissue samples of the dependent and non-dependent lung areas were collected. Histopathological examinations of the lung tissue as well as relative quantification of mRNA of IL-1ß, IL-6, iNOS, MMP1 and MMP9 by PCR were performed. Horses of group OLC had significantly less alveolar congestion and atelectasis but greater alveolar overdistension compared to groups NV and IPPV. In groups OLC and group IPPV an increase in IL-1ß/6 and MMP1/9 was detected compared to groups NV and C. In conclusion, in breathing spontaneously or IPPV-ventilated horses a higher degree of atelectasis was detected, whereas in OLC-ventilated horses a higher degree of overdistention was present. Elevated levels in IL and MMP might be early signs of VILI in ventilated horses.

NHS generic project: response from the wound care community.

This series of letters outlines the response from MA Healthcare, key opinion leaders, and industry to the news that the Government is planning to introduce a generic project for wound dressings, limiting products to three main suppliers.

NHS generic project: response from the wound care community.

This series of letters outlines the response from MA Healthcare, key opinion leaders and industry to the news that the Government is planning to introduce a generic project for wound dressings.

Temporal and concentration effects of isoflurane anaesthesia on intestinal tissue oxygenation and perfusion in horses.

The aim of this study was to assess the effect of duration of anaesthesia and concentration of isoflurane on global perfusion as well as intestinal microperfusion and oxygenation. Nine Warmblood horses were premedicated with xylazine; anaesthesia was induced with midazolam and ketamine, and maintained with isoflurane. Horses were ventilated to normocapnia. During 7 h of anaesthesia, mean arterial blood pressures (MAP), heart rate, central venous pressure, pulmonary artery pressure, expiratory isoflurane concentration (ETIso) and cardiac output using lithium dilution were measured; cardiac index (CI) was calculated. Intestinal microperfusion and oxygenation were measured using laser Doppler flowmetry and white-light spectrophotometry. Surface probes were placed via median laparotomy on the serosal and mucosal site of the jejunum and the pelvic flexion of the colon. After 3 h of constant ETIso (1.4%), ETIso was increased in 0.2% increments up to 2.4%, followed by a decrease to 1.2% and an increase to 1.4%. The CI and MAP decreased continuously with increasing ETIso to 40 ± 5 mL/kg/min and 52 ± 8 mmHg, respectively. Microperfusion and oxygenation remained unchanged until an ETIso of 2.0% resulted in CI and MAP of 48 ± 5 mL/kg/min and 62 ± 6 mmHg, respectively, and then decreased rapidly. When ETIso decreased back to baseline, CI, MAP, microperfusion and oxygenation recovered to baseline. Isoflurane concentration but not duration of isoflurane anaesthesia influenced central and intestinal oxygenation and perfusion in healthy horses. Under isoflurane, intestinal perfusion appeared to be preserved until a threshold MAP or blood flow was reached.

Evaluation of indirect impedance for measuring microbial growth in complex food matrices.

The suitability of indirect impedance to accurately measure microbial growth in real food matrices was investigated. A variety of semi-solid and liquid food products were inoculated with Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Lactobacillus plantarum, Pseudomonas aeruginosa, Escherichia coli, Salmonella enteriditis, Candida tropicalis or Zygosaccharomyces rouxii and CO2 production was monitored using a conductimetric (Don Whitely R.A.B.I.T.) system. The majority (80%) of food and microbe combinations produced a detectable growth signal. The linearity of conductance responses in selected food products was investigated and a good correlation (R(2) ≥ 0.84) was observed between inoculum levels and times to detection. Specific growth rate estimations from the data were sufficiently accurate for predictive modeling in some cases. This initial evaluation of the suitability of indirect impedance to generate microbial growth data in complex food matrices indicates significant potential for the technology as an alternative to plating methods.

Inclusivity, exclusivity and limit of detection of commercially available real-time PCR assays for the detection of Salmonella.

The traditional cultural detection of Salmonella spp. is both time- and labour-intensive. Salmonella is often a release criterion for the food industry and time to result is therefore an important factor. Storage of finished products and raw materials can be costly and may adversely impact available shelf-life. The application of real-time PCR for the detection of Salmonella spp. in food samples enables a potential time-saving of up to four days. The advancement of real-time PCR coupled with the development of commercially available systems in different formats has made this technology accessible for laboratories in an industrial environment. Ideally these systems are reliable and rapid as well as easy to use. The current study represents a comparative evaluation of seven commercial real-time PCR systems for the detection of Salmonella. Forty-nine target and twenty-nine non-target strains were included in the study to assess inclusivity and exclusivity. The limit of detection for each of the method was determined in four different food products. All systems evaluated were able to correctly identify the 49 Salmonella strains. Nevertheless, false positive results (Citrobacter spp.) were obtained with four of the seven systems. In milk powder and bouillon powder, the limit of detection was similar for all systems, suggesting a minimal matrix effect with these samples. Conversely, for black tea and cocoa powder some systems were prone to inhibition from matrix components. Up to 100% of the samples were inhibited using the proprietary extracts but inhibition could be reduced considerably by application of a DNA clean-up kit.

Comparison of rapid cultural methods for the detection of Salmonella species.

Three newly developed rapid cultural methods (Rapid Salmonella, Precis™ Salmonella, IBISA Salmonella) for the detection of Salmonella spp. were compared to a reference method. All methods performed comparably on inclusivity/exclusivity testing. Similar limits of detection were observed for all methods with milk, cocoa and bouillon matrices. Some tea varieties appeared to disturb the normal color formation of all selective agars tested.

Behavior of Enterobacter pulveris in amorphous and crystalline powder matrices treated with supercritical carbon dioxide.

The resistance of an Enterobacter pulveris strain to combined heat and supercritical carbon dioxide (scCO(2)) treatments in different powder matrices was examined. The strain proved resistant to scCO(2) treatment up to 50 MPa pressure at temperatures >73 °C for at least 20 min in a commercial infant formula. Water availability was shown to be important for the observed thermotolerance, because introduction of water in the scCO(2) gas flow during treatment resulted in a 1 log(10) cfu/g reduction of the initial inoculum. Interestingly, similar tolerance to heat and scCO(2) treatment was observed in a less complex matrix, a maltodextrin powder. In contrast, the bacterial strain proved sensitive to lower temperatures (55-65 °C) over shorter times (≤10 min) in a dextrose powder composed of crystalline particles. Therefore, the microorganism demonstrates heat sensitivity in the crystalline powder matrix closer to that of nonpowder liquid matrices. These data demonstrate the increased heat tolerance of the bacterium specifically in amorphous powders and indicate that this characteristic is not dependent on fat and other components commonly found in infant formula. The information is important in designing strategies to deal with contamination of powders with Enterobacteriacae, including pathogenic Cronobacter spp.

Timing and magnitude of C partitioning through a young loblolly pine (Pinus taeda L.) stand using 13C labeling and shade treatments.

The dynamics of rapid changes in carbon (C) partitioning within forest ecosystems are not well understood, which limits improvement of mechanistic models of C cycling. Our objective was to inform model processes by describing relationships between C partitioning and accessible environmental or physiological measurements, with a special emphasis on short-term C flux through a forest ecosystem. We exposed eight 7-year-old loblolly pine (Pinus taeda L.) trees to air enriched with (13)CO(2) and then implemented adjacent light shade (LS) and heavy shade (HS) treatments in order to manipulate C uptake and flux. The impacts of shading on photosynthesis, plant water potential, sap flow, basal area growth, root growth and soil CO(2) efflux rate (CER) were assessed for each tree over a 3-week period. The progression of the (13)C label was concurrently tracked from the atmosphere through foliage, phloem, roots and surface soil CO(2) efflux. The HS treatment significantly reduced C uptake, sap flow, stem growth and fine root standing crop, and resulted in greater residual soil water content to 1 m depth. Soil CER was strongly correlated with sap flow on the previous day, but not the current day, with no apparent treatment effect on the relationship. Although there were apparent reductions in new C flux belowground, the HS treatment did not noticeably reduce the magnitude of belowground autotrophic and heterotrophic respiration based on surface soil CER, which was overwhelmingly driven by soil temperature and moisture. The (13)C label was immediately detected in foliage on label day (half-life = 0.5 day), progressed through phloem by Day 2 (half-life = 4.7 days), roots by Days 2-4, and subsequently was evident as respiratory release from soil which peaked between Days 3 and 6. The δ(13)C of soil CO(2) efflux was strongly correlated with phloem δ(13)C on the previous day, or 2 days earlier. While the (13)C label was readily tracked through the ecosystem, the fate of root C through respiratory, mycorrhizal or exudative release pathways was not assessed. These data detail the timing and relative magnitude of C flux through various components of a young pine stand in relation to environmental conditions.

Influence of mechanical manipulations on the local inflammatory reaction in the equine colon.

REASONS FOR PERFORMING STUDY: Large intestinal diseases in horses are characterised by inflammation, which could arise from the disease process with some contribution from intestinal manipulation. The effects of the latter are unknown but important to surgeons and could contribute to post operative complications. OBJECTIVES: To characterise type and degree of intestinal inflammation induced by various mechanical stimuli in the equine ascending colon. METHODS: Laparotomy was performed in 12 horses, the left dorsal colon exteriorised and 3 segments randomly exposed to different mechanical manipulations: 1) enterotomy, 2) enterotomy and mucosal irritation and 3) serosal irritation. Intestinal biopsies were harvested before, immediately after and 30 min after each manipulation for histological evaluation. Eosinophils were detected with Luna's stain and neutrophils identified by immunohistochemical staining for calprotectin. Additionally, left dorsal colon samples from 14 horses from a jejunal ischaemia-reperfusion study were collected immediately after laparotomy (7 horses) and at the end of the experiment without previous manipulation of the colon (7 horses). Horses were subjected to euthanasia at the end of both studies. RESULTS: Redistribution of mucosal neutrophils and eosinophils towards the luminal surface and increased neutrophilic infiltration of the submucosa were demonstrated after serosal and mucosal irritation. All manipulations resulted in serosal infiltration with neutrophils. Laparotomy and small intestinal manipulation increased mucosal eosinophilic infiltration. CONCLUSIONS AND POTENTIAL RELEVANCE: Mechanical intestinal manipulation caused a rapid local inflammatory reaction in the mucosa, submucosa and serosa including a mucosal eosinophilic response. These changes could exacerbate existing inflammation in horses with large colon disease. Colic surgery can lead to intestinal inflammation in nonmanipulated intestine and this could contribute to a higher morbidity rate in horses after prolonged colic surgery. An intestinal biopsy should be collected at the beginning of surgery to avoid false interpretations.

Survival characteristics of environmental and clinically derived strains of Cronobacter sakazakii in infant milk formula (IMF) and ingredients.

AIMS: The study aimed to compare survival of Cronobacter sakazakii strains in plant-derived infant milk formula (IMF) ingredients and their thermotolerance in reconstituted IMF. METHODS AND RESULTS: Inulin and lecithin were inoculated with isolates of C. sakazakii including the typed clinical strains, NCTC 11467(T) and BAA 894; a mutant strain in which the wcaD gene had been disrupted; and two environmental strains isolated from IMF processing facilities. Samples were stored and examined for C. sakazakii. All strains were still detectable in both matrices after 338 days storage, except for the mutant strain that was no longer detectable at that time. Higher numbers of the environmental strains were recoverable after 338 days than the clinical strains. The thermotolerance of the five strains was investigated in reconstituted IMF at 55, 60 and 65°C. The clinically derived type strain, NCTC 11467(T), and the mutant strain were shown to be significantly more thermotolerant than other strains tested. CONCLUSIONS: Environmental strains were more persistent than the clinical strains in inulin and lecithin, indicating that patho-adaptation may have contributed to a reduction in the desiccation tolerance phenotype. However, the thermotolerance results could indicate that the ability to produce extracellular polysaccharide decreases thermotolerance. SIGNIFICANCE AND IMPACT OF THE STUDY: These results indicate that desiccation resistance may play a role in survival of C. sakazakii in dry IMF ingredients and processing plants; however, this trait may be of less importance in clinical environs.

An AcrAB-mediated multidrug-resistant phenotype is maintained following restoration of wild-type activities by efflux pump genes and their regulators.

In this study, we aimed to answer the following question: 'How does a bacterium become so resistant to a given antibiotic even though the levels of antibiotic to which it has become resistant remained constant in the patient?'Escherichia coli AG100 strain induced to high-level resistance due to overexpression of an AcrAB efflux pump was serially cultured in 10mg/L tetracycline for 60 passages. Between each passage it became increasingly resistant to tetracycline, beta-lactams and quinolones with concomitant restoration of wild-type AcrAB activity. Because the multidrug-resistant phenotype could not be reversed with transfer to drug-free medium or with efflux pump inhibitors, it may have resulted from activation of a 'mutator gene' system that reduced the 'energy consumption' associated with an overexpressed efflux pump system.

Microarray-based comparative genomic indexing of the Cronobacter genus (Enterobacter sakazakii).

Cronobacter (Enterobacter sakazakii) is a recently defined genus consisting of 6 species. To extend our understanding of the genetic relationship between Cronobacter sakazakii BAA-894 and the other species of this genus, microarray-based comparative genomic indexing (CGI) was undertaken to determine the presence/absence of genes identified in the former sequenced genome and to compare 276 selected open reading frames within the different Cronobacter strains. Seventy-eight Cronobacter strains (60 C. sakazakii, 8 C. malonaticus, 5 C. dublinensis, 2 C. muytjensii, 1 C. turicensis, 1 C. genomospecies 1, and 1 Cronobacter sp.) representing clinical and environmental isolates from various geographical locations were investigated. Hierarchical clustering of the CGI data showed that the species grouped as clusters. The 5 C. dublinensis and 2 C. muytjensii strains examined formed distinct species clusters. Moreover, all of the C. sakazakii and 3 of 8 C. malonaticus strains formed a large cluster. The remaining C. malonaticus strains formed a sub-group within a larger cluster that also contained C. turicensis, C. genomospecies 1, and an unknown Cronobacter sp. Cronobacter sakazakii and 3 of 8 C. malonaticus strains could be distinguished from the others within the collection by the presence of 10 fimbrial related genes. Similarly, capsule and/or lipopolysaccharide (LPS) related glycosyltransferases differentiated several of the C. sakazakii strains from each other.

Development and evaluation of rpoB based PCR systems to differentiate the six proposed species within the genus Cronobacter.

Although there are various PCR based methods described in the literature to detect the genus Cronobacter, none of these methods is able to differentiate the six proposed species within this genus. A species differentiation is important for epidemiological studies. Moreover, the different species show differences in sensitivity to chemical agents and antibiotics. Here we report for the first time different rpoB based PCR systems which enable the identification to species level of strains previously confirmed to belong to the genus Cronobacter. Different primer pairs based on the rpoB sequences of the six Cronobacter species type strains were designed. Thereafter, 57 target and non-target strains, previously described in the Cronobacter taxonomy paper, were included for the specificity evaluation. C. turicensis, C. muytjensii, C. dublinensis and C. genomospecies 1 can be reliably identified by the proposed single primer pairs. Only target strains showed a correctly sized amplification product, whereas no amplification product was obtained for all non-target strains used in this study (100% specificity). However, as the rpoB gene sequences of C. sakazakii and C. malonaticus are closely related, a two step procedure is necessary. We therefore recommend a two-step procedure in which the primer pairs Cmalf/Cmalr are used in a follow up PCR on strains that are found to be positive in the amplification with the C. sakazakii specific primers Csakf/Csakr.

Development and application of a novel peptide nucleic acid probe for the specific detection of Cronobacter genomospecies (Enterobacter sakazakii) in powdered infant formula.

Here, we report a fluorescence in situ hybridization (FISH) method for rapid detection of Cronobacter strains in powdered infant formula (PIF) using a novel peptide nucleic acid (PNA) probe. Laboratory tests with several Enterobacteriaceae species showed that the specificity and sensitivity of the method were 100%. FISH using PNA could detect as few as 1 CFU per 10 g of Cronobacter in PIF after an 8-h enrichment step, even in a mixed population containing bacterial contaminants.