Experimental infection of the pig with Mycobacterium ulcerans : a novel model for studying the pathogenesis of Buruli ulcer disease

Buruli ulcer (BU) is a slowly progressing, necrotising disease of the skin caused by infection with Mycobacterium ulcerans. Non-ulcerative manifestations are nodules, plaques and oedema, which may progress to ulceration of large parts of the skin. Histopathologically, BU is characterized by coagulative necrosis, fat cell ghosts, epidermal hyperplasia, clusters of extracellular acid fast bacilli (AFB) in the subcutaneous tissue and lack of major inflammatory infiltration. The mode of transmission of BU is not clear and there is only limited information on the early pathogenesis of the disease available.; For evaluating the potential of the pig as experimental infection model for BU, we infected pigs subcutaneously with different doses of M. ulcerans. The infected skin sites were excised 2.5 or 6.5 weeks after infection and processed for histopathological analysis. With doses of 2×107 and 2×106 colony forming units (CFU) we observed the development of nodular lesions that subsequently progressed to ulcerative or plaque-like lesions. At lower inoculation doses signs of infection found after 2.5 weeks had spontaneously resolved at 6.5 weeks. The observed macroscopic and histopathological changes closely resembled those found in M. ulcerans disease in humans.; Our results demonstrate that the pig can be infected with M. ulcerans. Productive infection leads to the development of lesions that closely resemble human BU lesions. The pig infection model therefore has great potential for studying the early pathogenesis of BU and for the development of new therapeutic and prophylactic interventions

Characterization of Canine Dendritic Cells in Healthy, Atopic, and Non-allergic Inflamed Skin

Atopic dermatitis in humans and dogs is a chronic relapsing allergic skin disease. Dogs show a spontaneous disease similar to the human counterpart and represent a model to improve our understanding of the immunological mechanisms, the pathogenesis of the disease, and new therapy development. The aim of the study was to determine the frequency and phenotype of dendritic cells (DC) in the epidermis and dermis of healthy, canine atopic dermatitis lesional, and non-allergic inflammatory skin to further validate the model and to obtain insights into the contribution of DC to the pathogenesis of skin diseases in dogs. We first characterized canine skin DC using flow-cytometric analysis of isolated skin DC combined with an immunohistochemical approach. A major population of canine skin dendritic cells was identified as CD1c+CD11c+CD14−CD80+MHCII+MAC387− cells, with dermal DC but not Langerhans cells expressing CD11b. In the epidermis of lesional canine atopic dermatitis and non-allergic inflammatory skin, we found significantly more dendritic cells compared with nonlesional and control skin. Only in canine atopic dermatitis skin did we find a subset of dendritic cells positive for IgE, in the epidermis and the dermis. Under all inflammatory conditions, dermal dendritic cells expressed more CD14 and CD206. MAC387+ putative macrophages were absent in healthy but present in inflamed skin, in particular during non-allergic diseases. This study permits a phenotypic identification and differentiation of canine skin dendritic cells and has identified markers and changes in dendritic cells and macrophage populations related to allergic and non-allergic inflammatory conditions. Our data suggest the participation of dendritic cells in the pathogenesis of canine atopic dermatitis similar to human atopic dermatitis and further validate the only non-murine spontaneous animal model for this diseas

Photon Distribution Function for Long-Distance Propagation of Partially Coherent Beams through the Turbulent Atmosphere

The photon density operator function is used to calculate light beam propagation through turbulent atmosphere. A kinetic equation for the photon distribution function is derived and solved using the method of characteristics. Optical wave correlations are described in terms of photon trajectories that depend on fluctuations of the refractive index. It is shown that both linear and quadratic disturbances produce sizable effects for long-distance propagation. The quadratic terms are shown to suppress the correlation of waves with different wave vectors. We examine the intensity fluctuations of partially coherent beams (beams whose initial spatial coherence is partially destroyed). Our calculations show that it is possible to significantly reduce the intensity fluctuations by using a partially coherent beam. The physical mechanism responsible for this pronounced reduction is similar to that of the Hanbury-Braun, Twiss effect.Comment: 28 pages, 4 figure

Complement C3dg-mediated erythrophagocytosis: Implications for paroxysmal nocturnal hemoglobinuria

The clinical management of paroxysmal nocturnal hemoglobinuria (PNH), a rare but life-threatening hematologic disease, has fundamentally improved with the introduction of a therapeutic that prevents complement-mediated intravascular hemolysis. However, a considerable fraction of PNH patients show insufficient treatment response and remain transfusion dependent. Because the current treatment only prevents C5-induced lysis but not upstream C3 activation, it has been speculated that ongoing opsonization with C3 fragments leads to recognition and phagocytosis of PNH erythrocytes by immune cells. Here, for the first time, we provide experimental evidence for such extravascular hemolysis and demonstrate that PNH erythrocytes from anti–C5-treated patients are phagocytosed by activated monocytes in vitro. Importantly, we show that this uptake can be mediated by the end-stage opsonin C3dg, which is not traditionally considered a phagocytic marker, via interaction with complement receptor 3 (CR3). Interaction studies confirmed that C3dg itself can act as a ligand for the binding domain of CR3. The degree of C3dg-mediated erythrophagocytosis in samples from different PNH patients correlated well with the individual level of C3dg opsonization. This finding may guide future treatment options for PNH but also has potential implications for the description and management of other complement-mediated diseases

Regulators of complement activity mediate inhibitory mechanisms through a common C3b‐binding mode

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Presentations to an urban emergency department in Bern, Switzerland associated with acute recreational drug toxicity

Although the recreational use of psychoactive substances is common there is only limited systematic collection of data on acute drug toxicity or hospital presentations. Currently, data from Switzerland are only available from the University Hospital of Basel. The present study aimed to describe the presentations due to recreational drug use at an emergency department in Bern, Switzerland during a 4 year period.; Retrospective analysis of cases presenting from May 2012 to April 2016 at the emergency department of the University Hospital of Bern, Switzerland, with symptoms/signs consistent with acute toxicity of recreational drug use. The cases were retrieved using a comprehensive full-text search algorithm of the electronic health records. Isolated ethanol intoxications were excluded.; During the study period, 503 of the 157,328 emergency department attendances were directly related to acute toxicity of substances used recreationally. The mean patient age was 33 years (range 16-74), 68% were male. Alcohol co-ingestion was reported in 54% of the cases, and use of more than one recreational drug in 37% of the cases. Most presentations were related to cocaine (29%), cannabis (26%), heroin (20%) and benzodiazepines/sedatives (18%). Urine drug screening immunoassay was available in 277 cases (55%). The most frequently detected substances were cannabis (29%), cocaine (22%), benzodiazepines (21%) and opioids excluding methadone (20%). There were only two intoxications with novel psychoactive substances (NPSs): One with methylone and one with 2,5-dimethoxy-4(n)-propylphenethylamine (2C-P). The majority of patients (58%) displayed impaired consciousness (Glasgow Coma Scale (GCS) <15) upon presentation and/or pre-hospital; 21% were unconscious (GCS <8). Other frequent symptoms were agitation (36%), tachycardia (29%), and anxiety (24%). Severe complications included two fatalities, three acute myocardial infarctions, two intracranial haemorrhages, as well as psychosis and seizures in 71 and 26 cases, respectively.; Most medical problems related to recreational drug use were associated with cocaine and cannabis use and were mainly characterised by central nervous system depression, sympathomimetic toxicity and/or psychiatric disorders. Presentations related to acute toxicities of NPSs appear to be uncommon, while prescription drugs were after classical recreational drugs the substances most commonly reported