Aβ Peptide Fibrillar Architectures Controlled by Conformational Constraints of the Monomer

Anomalous self-assembly of the Aβ peptide into fibrillar amyloid deposits is strongly correlated with the development of Alzheimer's disease. Aβ fibril extension follows a template guided “dock and lock” mechanism where polymerisation is catalysed by the fibrillar ends. Using surface plasmon resonance (SPR) and quenched hydrogen-deuterium exchange NMR (H/D-exchange NMR), we have analysed the fibrillar structure and polymerisation properties of both the highly aggregation prone Aβ1–40 Glu22Gly (Aβ40Arc) and wild type Aβ1–40 (Aβ40WT). The solvent protection patterns from H/D exchange experiments suggest very similar structures of the fibrillar forms. However, through cross-seeding experiments monitored by SPR, we found that the monomeric form of Aβ40WT is significantly impaired to acquire the fibrillar architecture of Aβ40Arc. A detailed characterisation demonstrated that Aβ40WT has a restricted ability to dock and isomerise with high binding affinity onto Aβ40Arc fibrils. These results have general implications for the process of fibril assembly, where the rate of polymerisation, and consequently the architecture of the formed fibrils, is restricted by conformational constraints of the monomers. Interestingly, we also found that the kinetic rate of fibril formation rather than the thermodynamically lowest energy state determines the overall fibrillar structure

High Genetic Diversity among Community-Associated Staphylococcus aureus in Europe: Results from a Multicenter Study

Background: Several studies have addressed the epidemiology of community-associated Staphylococcus aureus (CA-SA) in Europe; nonetheless, a comprehensive perspective remains unclear. In this study, we aimed to describe the population structure of CA-SA and to shed light on the origin of methicillin-resistant S. aureus (MRSA) in this continent. Methods and Findings: A total of 568 colonization and infection isolates, comprising both MRSA and methicillin-susceptible S. aureus (MSSA), were recovered in 16 European countries, from community and community-onset infections. The genetic background of isolates was characterized by molecular typing techniques (spa typing, pulsed-field gel electrophoresis and multilocus sequence typing) and the presence of PVL and ACME was tested by PCR. MRSA were further characterized by SCCmec typing. We found that 59 % of all isolates were associated with community-associated clones. Most MRSA were related with USA300 (ST8-IVa and variants) (40%), followed by the European clone (ST80-IVc and derivatives) (28%) and the Taiwan clone (ST59-IVa and related clonal types) (15%). A total of 83 % of MRSA carried Panton-Valentine leukocidin (PVL) and 14 % carried the arginine catabolic mobile element (ACME). Surprisingly, we found a high genetic diversity among MRSA clonal types (ST-SCCmec), Simpson’s index of diversity = 0.852 (0.788–0.916). Specifically, about half of the isolates carried novel associations between genetic background and SCCmec. Analysis by BURP showed that some CA-MSSA and CA-MRS

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Housing environment influences the need for pain relief during post-operative recovery in mice

The impact of invasive experimental procedures on perceived stress and pain may be dependent on both physical and social environmental conditions. The aim of this study was to evaluate the effects of a physically and a socially enriched environment on the need for pain relief following painful experimental procedures. A non-invasive method to administer analgesics post-operatively is by means of self-administration which is a feasible objective method to measure perceived pain during the post-operative recovery period. In the present study eight groups of mice housed in different conditions underwent the surgical procedure of caecal manipulation or only exposure to anaesthesia. After surgery the mice were given the choice to self-administer an analgesic available in one of their water bottles during two post-operative weeks. It was shown that socially enriched mice drank i.e. self-administered, less from the analgesic containing water than the non-enriched and socially deprived groups. Mice that underwent operation self-administered more analgesic than mice that received only anaesthesia without operation. The findings indicate that the recovery environment can contribute positively to attenuate the need for pain relief in animals submitted to invasive procedures. © 2010 Elsevier Inc

Sleep and influenza A viral infections in murine models

Narcolepsy is a rare neurological sleep disorder. However, after the beginning of the influenza A (H1N1) pandemic, an increased incidence of narcolepsy was observed, especially in young people aged between 4-19 years. In the present study, infection of Rag1-/- (lacking B and T cells) and wild-type mice with a mouse-neuroadapted or a 2009 H1N1 influenza A virus strain was used to elucidate pathogenetic mechanisms. Electroencephalogram (EEG) and actimetry were recorded by NeuroLogger\uae device which allows the mouse to move freely in its cage. Infected mice were sacrificed following the onset of sickness signs and brain samples were collected. In Rag1-/- mice, immunohistochemistry for antigens of the mouse-neuroadapted influenza strain showed hypothalamic and upper brainstem viral localization, including neurons involved in sleep-wakefulness regulation. Moreover, preliminary EEG analyses showed severe changes in the sleep-wake pattern in the infected Rag1-/- mice. Levels of viral RNA and inflammatory markers were analysed by RT-PCR. Interestingly, preliminary data indicate that the presence of transcripts encoding the non-structural viral protein (NS1) in the brain of mice infected with either viral strain was transient in wild-type mice, but persisted in the Rag1-/- mice. Up-regulation of transcripts of inducible nitric oxide synthase was seen in infected wild-type mice. In conclusion, our data suggest that infection of wild-type and Rag1-/- mice may provide useful models to study changes in sleep patterns caused by H1N1 influenza A virus strains, and may increase our understanding of the role of direct viral versus innate and adaptive immune response effects. (Supported by Swedish MPA

Simultaneous imaging of amyloid-β and lipids in brain tissue using antibody-coupled liposomes and time-of-flight secondary ion mass spectrometry

The spatial localization of amyloid-β peptide deposits, the major component of senile plaques in Alzheimer\u27s disease (AD), was mapped in transgenic AD mouse brains using time-of-flight secondary ion mass spectrometry (ToF-SIMS), simultaneously with several endogenous molecules that cannot be mapped using conventional immunohistochemistry imaging, including phospholipids, cholesterol and sulfatides. Whereas the endogenous lipids were detected directly, the amyloid-β deposits, which cannot be detected as intact entities with ToF-SIMS because of extensive ion-induced fragmentation, were identified by specific binding of deuterated liposomes to antibodies directed against amyloid-β. Comparative investigation of the amyloid-β deposits using conventional immunohistochemistry and fluorescence microscopy suggests similar sensitivity but a more surface-confined identification due to the shallow penetration depth of the ToF-SIMS signal. The recorded ToF-SIMS images thus display the localization of lipids and amyloid-β in a narrow (∼10 nm) two-dimensional plane at the tissue surface. As compared to a frozen nontreated tissue sample, the liposome preparation protocol generally increased the signal intensity of endogenous lipids, likely caused by matrix effects associated with the removal of salts, but no severe effects on the tissue integrity and the spatial distribution of lipids were observed with ToF-SIMS or scanning electron microscopy (SEM). This method may provide an important extension to conventional tissue imaging techniques to investigate the complex interplay of different kinds of molecules in neurodegenerative diseases, in the same specimen. However, limitations in target accessibility of the liposomes as well as unspecific binding need further consideration. \ua9 2014 American Chemical Society

Alterations in brain leptin signalling in spite of unchanged CSF leptin levels in Alzheimer’s disease

Several studies support the relation between leptin and Alzheimer’s disease (AD). We show that leptin levels in CSF are unchanged as subjects progress to AD. However, in AD hippocampus, leptin signalling was decreased and leptin localization was shifted, being more abundant in reactive astrocytes and less in neurons. Similar translocation of leptin was found in brains from Tg2576 and apoE4 mice. Moreover, an enhancement of leptin receptors was found in hippocampus of young Tg2576 mice and in primary astrocytes and neurons treated withAb1-42. In contrast, old Tg2576 mice showed decreased leptin receptors levels. Similar findings to those seen in Tg2576 mice were found in apoE4, but not in apoE3 mice. These results suggest that leptin levels are intact, but leptin signalling is impaired in AD. Thus, Ab accumulation and apoE4 genotype result in a transient enhancement of leptin signalling that might lead to a leptin resistance state over time

MRSA infections among patients in the emergency department: a European multicentre study

MRSA is a therapeutic concern worldwide, and a major agent of community-acquired skin and soft tissue infections (CA-SSTIs). While the US epidemiology of MRSA in CA-SSTIs is well described and reports the high prevalence of the USA300 clone, data on the European situation are lacking

Multicenter Study of Cronobacter sakazakii Infections in Humans, Europe, 2017

Cronobacter sakazakii has been documented as a cause of life-threating infections, predominantly in neonates. We conducted a multicenter study to assess the occurrence of C. sakazakii across Europe and the extent of clonality for outbreak detection. National coordinators representing 24 countries in Europe were requested to submit all human C. sakazakii isolates collected during 2017 to a study center in Austria. Testing at the center included species identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, subtyping by whole-genome sequencing (WGS), and determination of antimicrobial resistance. Eleven countries sent 77 isolates, including 36 isolates from 2017 and 41 historical isolates. Fifty-nine isolates were confirmed as C. sakazakii by WGS, highlighting the challenge of correctly identifying Cronobacter spp. WGS-based typing revealed high strain diversity, indicating absence of multi-national outbreaks in 2017, but identified 4 previously unpublished historical outbreaks. WGS is the recommended method for accurate identification, typing, and detection of this pathogen.Molecular basis of bacterial pathogenesis, virulence factors and antibiotic resistanc