Substrate Selection Criteria in Regulated Intramembrane Proteolysis

Alzheimer's disease is the most common form of dementia encountered in an aging population. Characteristic amyloid deposits of Aβ peptides in the brain are generated through cleavage of amyloid precursor protein (APP) by γ-secretase, an intramembrane protease. Cryo-EM structures of substrate γ-secretase complexes revealed details of the process, but how substrates are recognized and enter the catalytic site is still largely ignored. γ-Secretase cleaves a diverse range of substrate sequences without a common consensus sequence, but strikingly, single point mutations within the transmembrane domain (TMD) of specific substrates may greatly affect cleavage efficiencies. Previously, conformational flexibility was hypothesized to be the main criterion for substrate selection. Here we review the 3D structure and dynamics of several γ-secretase substrate TMDs and compare them with mutants shown to affect the cleavage efficiency. In addition, we present structural and dynamic data on ITGB1, a known nonsubstrate of γ-secretase. A comparison of biophysical details between these TMDs and changes generated by introducing crucial mutations allowed us to unravel common principles that differ between substrates and nonsubstrates. We identified three motifs in the investigated substrates: a highly flexible transmembrane domain, a destabilization of the cleavage region, and a basic signature at the end of the transmembrane helix. None of these appears to be exclusive. While conformational flexibility on its own may increase cleavage efficiency in well-known substrates like APP or Notch1, our data suggest that the three motifs seem to be rather variably combined to determine whether a transmembrane helix is efficiently recognized as a γ-secretase substrate.

Long-term memory consolidation of new words in children with self-limited epilepsy with centro-temporal spikes

Accelerated long-term forgetting has been studied and demonstrated in adults with epilepsy. In contrast, the question of long-term consolidation (delays > 1 day) in children with epilepsy shows conflicting results. However, childhood is a period of life in which the encoding and long-term storage of new words is essential for the development of knowledge and learning. The aim of this study was therefore to investigate long-term memory consolidation skills in children with self-limited epilepsy with centro-temporal spikes (SeLECTS), using a paradigm exploring new words encoding skills and their long-term consolidation over one-week delay. As lexical knowledge, working memory skills and executive/attentional skills has been shown to contribute to long-term memory/new word learning, we added standardized measures of oral language and executive/attentional functions to explore the involvement of these cognitive skills in new word encoding and consolidation. The results showed that children with SeLECTS needed more repetitions to encode new words, struggled to encode the phonological forms of words, and when they finally reached the level of the typically developing children, they retained what they had learned, but didn't show improved recall skills after a one-week delay, unlike the control participants. Lexical knowledge, verbal working memory skills and phonological skills contributed to encoding and/or recall abilities, and interference sensitivity appeared to be associated with the number of phonological errors during the pseudoword encoding phase. These results are consistent with the functional model linking working memory, phonology and vocabulary in a fronto-temporo-parietal network. As SeLECTS involves perisylvian dysfunction, the associations between impaired sequence storage (phonological working memory), phonological representation storage and new word learning are not surprising. This dual impairment in both encoding and long-term consolidation may result in large learning gap between children with and without epilepsy. Whether these results indicate differences in the sleep-induced benefits required for long-term consolidation or differences in the benefits of retrieval practice between the epilepsy group and healthy children remains open. As lexical development is associated with academic achievement and comprehension, the impact of such deficits in learning new words is certainly detrimental.

Cell-free protein production of a gamma secretase homolog

Cleavage of the transmembrane domain (TMD) of amyloid-β precursor protein (APP) by γ-secretase, an intramembrane aspartyl protease, generates Aβ peptides of various lengths that form plaques in the brains of Alzheimer's disease patients. Although the debate has not been finally resolved whether these plaques trigger the onset of Alzheimer's or are side products, disease-related mutations suggest their implication in the etiology of the dementia. These occur both in presenilin, the catalytic subunit of γ-secretase, and in the TMD of APP. Despite two seminal cryo-electron microscopy structures that show the complex of γ-secretase with its substrates APP and Notch, the mechanism of γ-secretase is not yet fully understood. Especially on which basis it selects its substrates is still an enigma. The presenilin homolog PSH from the archaeon Methanoculleus marisnigri JR1 (MCMJR1) is catalytically active without accessory proteins in contrast to γ-secretase making it an excellent model for studies of the basic cleavage process. We here focused on the cell-free expression of PSH screening a range of conditions. Cleavage assays to verify the activity show that not only the yield, but mainly the activity of the protease depends on the careful selection of expression conditions. Optimal results were found for a cell-free expression at relatively low temperature, 20 °C, employing cell lysates prepared from E. coli Rosetta cells. To speed up protein preparation for immediate functional assays, a crude purification protocol was developed. This allows to produce ready-made PSH in a fast and efficient manner in less than two days.

Characteristics and outcomes in patients with infective endocarditis caused by Enterococcus faecium and Enterococcus faecalis

Background

Enterococcus faecalis is the third most common cause of infective endocarditis (IE) and has been associated with a higher risk of relapse and death. Within the enterococcus species, E. faecium is the second most frequent cause of IE. As IE from E. faecalis or E. faecium most likely have different presentations and outcomes, research is needed for individualised and optimised clinical management.

Purpose

This study aims to characterise baseline characteristics and clinical outcomes for patients with IE caused by E. faecalis or E. faecium, including short- and long-term mortality and relapse. Additionally, we aim to determine risk factors associated with IE caused by the two bacterial species.

Methods

This is a retrospective study of patients hospitalised with at least one positive blood culture with E. faecalis or E. faecium between January 1, 2016 and December 31, 2018 at two large hospitals in Denmark. IE was diagnosed according to the modified Duke criteria. Index and follow-up data were collected from medical records. Categorical values were compared using chi-square test and categorial data using students t-test.

Results

614 patients had a positive blood culture with either E. faecalis (n=279) or E. faecium (n=335). Of these, 64 (10.4%) patients developed IE; E. faecalis in 56 patients (87.5%, male 83.3%, mean age 70 years (SD 14)) and E. faecium in 8 patients (12.5%, male 75.0%, mean age 65 years (SD 13)). The prevalence of IE was 20.1% for E. faecalis bacteraemia and 2.4% for E. faecium bacteraemia (p<0.001). Embolic events during primary admission were seen more often in the E. faecium group (62.5%) compared to the E. faecalis group (10.7%) (p=0.002). Both groups had multiple co-morbidities without significant differences between groups (Table 1).

Nineteen (40.4%) of the patients with E. faecalis IE had a minimum of one previous admission with E. faecalis bacteraemia within the last year before the IE diagnosis, whereas this was not seen for any patients with E. faecium IE. The 30-days all-cause mortality was 5.4% for patients with E. faecalis IE and 25% for patients with E. faecium IE (p=0.22). After a median follow up of 3.1 years (IQR=0.46–3.94) all-cause mortality was 55.4% for patients with E. faecalis IE and 62.5% for patients with E. faecium IE (p=1.00) (Table 1).

Conclusion

The prevalence of IE was significantly higher in patients with E. faecalis bacteraemia than with E. faecium bacteraemia. While the prevalence of complications was higher in patients with E. faecium IE, the difference was only significant for embolic events. This indicates that E. faecium IE is associated with a worse outcome compared to the outcome in patients with E. faecalis IE. All-cause mortality was above 50% for both groups, i.e. considerably higher than generally seen in patients with IE. These findings may be of importance of management of patients with E. faecalis or with E. faecium bacteraemia – and endocarditis.

Funding Acknowledgement

Type of funding sources: None.

Long-term impact of persistent vegetations at 6 month followup after treatment of infective endocarditis: a substudy of the Partial Oral vs Intravenous Antibiotic Treatment of Endocarditis (POET) tria

Background

Our knowledge of changes in vegetation size throughout the course of infective endocarditis (IE) and the impact of persistent vegetations on mortality or embolization after completed antibiotic treatment is sparse. No study has previously investigated the prevalence or clinical impact of persistent vegetations on transthoracic echocardiography (TTE) at 6-months follow-up after ended IE treatment.

Purpose

To investigate the association between persistent vegetations at the 6-months TTE after treatment for IE and long-term prognosis as assessed in the POET trial.

Methods

The POET trial was a nationwide, multicenter RCT, randomizing 400 patients to either partial oral or intravenous (IV) antibiotic treatment of left-sided IE, after initial stabilization of infection using conventional IV therapy.

A persistent vegetation was defined as a vegetation seen on 6-months follow-up TTE (4–7 months) after ended antibiotic treatment for IE. In the POET trial, primary outcome was defined as 1) all-cause mortality, 2) unplanned cardiac surgery, 3) embolic events or 4) relapse of bacteremia, in the 5-year follow-up period. Patients without TTE due to death or lack of available TTE were excluded.

Results

Out of 400 patients, 20 were excluded due to death during 6-months follow-up, and 201 were excluded due to unavailable TTE, leaving 179 TTEs for analysis.

At 6-months follow-up, a persistent vegetation was seen in 30 patients (16.7%, 21 males (70%), mean age 69.6 years (SD 7.7)) (Table 1). Seventeen patients (56.7%) had a persistent vegetation on the aortic valve and 13 patients (43.3%) on the mitral valve. More patients without a persistent vegetation had undergone initial surgical treatment of IE than those with a vegetation (57.7 vs 23.3%, p=0.001). In all surgically treated patients with persistent vegetation at 6-months follow-up, the vegetation was found on another valve than the operated valve.

The composite primary outcome from 6-months follow-up and until 5-year follow-up occurred in 8 patients (26.7%) with a persistent vegetation, compared to 38 patients (25.5%) (p=1.00) without. (Table 2) In patients randomized for peroral treatment, no significant difference in prevalence of persistent vegetation was found (15 patients (50%) with persistent vegetations vs. 74 patients (49.7%) without, p=1.00).

Conclusion

The occurrence of persistent vegetations at 6 months follow-up was 16.7%. There was no association between persistent vegetations at 6-months follow-up and the occurrence of the primary outcome after 5 years follow-up, suggesting that the risk associated with residual vegetations after end of antibiotic treatment is negligible after 6-months.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The Danish Heart Foundation

Large-Scale Recombinant Production of the SARS-CoV-2 Proteome for High-Throughput and Structural Biology Applications

The highly infectious disease COVID-19 caused by the Betacoronavirus SARS-CoV-2 poses a severe threat to humanity and demands the redirection of scientific efforts and criteria to organized research projects. The international COVID19-NMR consortium seeks to provide such new approaches by gathering scientific expertise worldwide. In particular, making available viral proteins and RNAs will pave the way to understanding the SARS-CoV-2 molecular components in detail. The research in COVID19-NMR and the resources provided through the consortium are fully disclosed to accelerate access and exploitation. NMR investigations of the viral molecular components are designated to provide the essential basis for further work, including macromolecular interaction studies and high-throughput drug screening. Here, we present the extensive catalog of a holistic SARS-CoV-2 protein preparation approach based on the consortium's collective efforts. We provide protocols for the large-scale production of more than 80% of all SARS-CoV-2 proteins or essential parts of them. Several of the proteins were produced in more than one laboratory, demonstrating the high interoperability between NMR groups worldwide. For the majority of proteins, we can produce isotope-labeled samples of HSQC-grade. Together with several NMR chemical shift assignments made publicly available on covid19-nmr.com, we here provide highly valuable resources for the production of SARS-CoV-2 proteins in isotope-labeled form.

Hemoglobin level at stabilization is associated with long-term all-cause mortality in patients with left-sided endocarditis, a POET substudy

Background

Left-sided infectious endocarditis (IE) has a high 1-year mortality. Anemia is a common finding in patients with IE, yet little is known about frequency, severity, and associated outcomes in this setting.

Purpose

To examine the relationship between Hemoglobin (Hgb) level measured at IE stabilization (time of randomization) in the Partial Oral versus intravenous Antibiotic Treatment of Endocarditis (POET) trial - and long-term all-cause mortality.

Methods

In the POET trial, 400 patients with left-sided IE were randomized, after medical and/or surgical stabilization, to conventional antibiotic treatment or partial oral treatment. Only non-surgically treated patients were considered in this study. Patients were divided by quartiles into four groups based on Hgb level at randomization.

Results

We examined 248 patients with non-surgically treated IE. Median time from diagnosis of IE to randomization was 14 days (IQ 12–19). At long-term follow-up (median 3.2 years, IQ 2.18–4.60), 71 patients had died (28.6%). Patients in the lowest quantile (Hgb ≤6.0 mmol) had a HR of 4.17 (95% CI 1.81–9.61, p<0.001) for death compared to patients in the highest quantile (Hgb >7.5 mmol/L). This association remained significant after multivariable adjustment for age, sex, renal disease, C-Reactive Protein, and Prosthetic heart valve (HR 2.69, 95% CI 1.11–6.50); p=0.028).

Conclusion

Low Hemoglobin level at stabilization in patients with IE was associated with an increased risk of long-term mortality. Whether intensified treatment of anemia in patients with IE could improve long-term outcome requires investigation.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): The Danish Heart Foundation, The Capital Regions Research Council

Transscleral Optical Phase Imaging of the Human Retina

In-vivo observation of the human retina at the cellular level is crucial to detect the first signs of retinal diseases and properly treat them. Despite the phenomenal advances in adaptive optics (AO) systems, clinical imaging of many retinal cells is still elusive due to the low signal-to-noise ratio induced by transpupillary illumination. We present a transscleral optical phase imaging (TOPI) method, which relies on high-angle oblique illumination of the retina, combined with AO, to enhance cell contrast. Examination of eleven healthy volunteer eyes, without pupil dilation, shows the ability of this method to produce in-vivo images of retinal cells, from the retinal pigment epithelium to the nerve fibre layer. This method also allows the generation of high-resolution label-free ex-vivo phase images of flat-mounted retinas. The 4.4°x 4.4° field-of-view in-vivo images are recorded in less than 10 seconds, opening new avenues in the exploration of healthy and diseased retinas.

Improving antibiotic treatment of bacterial biofilm by hyperbaric oxygen therapy: Not just hot air

Bacteria and fungi show substantial increased recalcitrance when growing as infectious biofilms. Chronic infections caused by biofilm growing microorganisms is considered a major problem of modern medicine. New strategies are needed to improve antibiotic treatment of biofilms. We have improved antibiotic treatment of bacterial biofilms by reviving the dormant bacteria and thereby make them susceptible to antibiotics by means of reoxygenation. Here we review the rationale for associating lack of oxygen with low susceptibility in infectious biofilm, and how hyperbaric oxygen therapy may result in reoxygenation leading to enhanced bactericidal activity of antibiotics. We address issues of feasibility and potential adverse effects regarding patient safety and development of resistance. Finally, we propose means for supplying reoxygenation to antibiotic treatment of infectious biofilm with the potential to benefit large groups of patients.

P3665Prevalence of infective endocarditis in patients with positive blood cultures: a Danish nationwide study

Background

Increasing attention has been given to the risk of infective endocarditis (IE) in patients with certain blood stream infections (BSI). Previous studies have been conducted on selected patient cohorts, yet unselected data are sparse.

Purpose

To investigate the nationwide prevalence of diagnosed IE in BSIs with bacteria typically associated with IE.

Methods

By crosslinking nationwide registries from 2010–2016, we identified patients with BSIs typically associated with IE: Enterococcus faecalis, Staphylococcus, Streptococcus spp., and coagulase negative staphylococci (CoNS) and examined the concurrent IE prevalence. A trend test was used to examine temporal changes in the prevalence of IE.

Results

In total 60,119 BSIs, distributed with 15,407, 16,790, and 27,922 BSIs were identified in the periods of 2010–2011, 2012–2013, and 2014–2016, respectively.

Patients with E. Faecalis had the highest prevalence of diagnosed IE (16.3%) followed by S. aureus (10.2%), Streptococcus spp. (7.3%), and CoNS (1.6%) (Figure). During the study period, the prevalence of IE among patients with E. faecalis increased significantly (p=0.003), Male patients had higher prevalence of IE for all microorganisms investigated compared with females. A significant increase in the prevalence of IE was seen for E. faecalis, Streptococcus spp., and CoNS with increasing age.

Percent with endocarditis

Conclusion

For E. faecalis BSI, 1 in 6 had IE, for S. aureus BSI 1 in 10 had IE, and for Streptococcus spp. 1 in 14 had IE. Our results support screening for IE in patients with E. faecalis, S. aureus, or Streptococcus spp. BSI in order to offer appropriate therapy.

A comparative performance analysis of stand-alone, off-grid solar-powered sodium hypochlorite generators

Sodium hypochlorite (NaClO) is a chemical commodity widely employed as a disinfection agent in water treatment applications. Its production commonly follows electrochemical routes in an undivided reactor. Powering the process with photovoltaic (PV) electricity holds the potential to install stand-alone, independent generators and reduce the NaClO production cost. This study reports the comparative assessment of autonomous, solar-powered sodium hypochlorite generators employing different photovoltaic (PV) technologies: silicon hetero-junction (SHJ) and multi-junction (MJ) solar cells. For Si hetero-junctions, the series connection of either four or five SHJ (4SHJ and 5SHJ, respectively) cells was implemented to obtain the reaction potential required. MJ cells were illuminated by a novel planar solar concentrator that guarantees solar tracking with minimal linear displacements. The three solar-hypochlorite generators were tested under real atmospheric conditions, demonstrating solar-to-chemical conversion efficiencies (SCE) of 9.8% for 4SHJ, 14.2% for 5SHJ and 25.1% for MJ solar cells, respectively. Simulations based on weather databases allowed us to assess efficiencies throughout the entire model year and resulted in specific sodium hypochlorite yearly production rates between 7.2–28 g_NaClO cm⁻² (referred to the PV surface), depending on the considered PV technology, location, and deployment of electronics converters. The economic viability and competitiveness of solar hypochlorite generators have been investigated and compared with an analog disinfection system deploying ultraviolet lamps. Our study demonstrates the feasibility of off-grid, solar-hypochlorite generators, and points towards the implementation of SHJ solar cells as a reliable technology for stand-alone solar-chemical devices.

Solar-powered electrochemical technologies can be employed to generate valuable chemical commodities on-site. We demonstrate solar-driven production of sodium hypochlorite, a widely employed water disinfection agent.

Le syndrome postgarde de nuit chez les médecins urgentistes : caractéristiques et facteurs influençants

Introduction : Les urgentistes connaissent une privation de sommeil en lendemain de garde. Beaucoup ont des perceptions ou des comportements inhabituels que nous appelons syndrome post-garde de nuit (PGN). L’objectif principal était de caractériser le syndrome PGN des urgentistes. Les objectifs secondaires étaient d’établir une note évaluant le syndrome PGN et de déterminer les facteurs influençant ce syndrome PGN.

Méthode : Étude prospective de cohorte, observationnelle, multicentrique, auprès des urgentistes du Gard et de l’Hérault entre janvier et juin 2017. Deux questionnaires informatiques anonymes étaient diffusés aux structures d’urgences du Gard et de l’Hérault. En journée normale, hors sortie de garde, un questionnaire colligeait les symptômes ressentis habituellement en lendemain de garde, à coter entre 0 et 10. En sortie de garde, un autre questionnaire s’intéressait au ressenti de la garde réalisée et aux caractéristiques de cette garde. Les médecins étaient encouragés à répondre aux deux questionnaires.

Résultats : Cent treize médecins (45 %) ont répondu, 67 (59 %) à distance d’une garde et 46 (41 %) en post-garde immédiat. Le syndrome PGN comprend des symptômes somatiques (échelle visuelle analogique (EVA) = 5 [2–8]), comportementaux (EVA = 7 [3–8]), liés à l’humeur (EVA = 7[5–8]) et psychiques (EVA = 6 [4–8]). Ces symptômes en post-garde immédiat étaient ressentis de manière moins importante que lorsque décrit à distance (respectivement p = 0,001, p <0,001, p < 0,001, p = 0,002). Les gardes de SMUR (service mobile d’urgence et de réanimation) et de traumatologie étaient associées à un syndrome PGN moins marqué (respectivement p =0,035 et p = 0,02) que les gardes des filières médico-chirurgicales.

Conclusion : Il s’agit de la première évaluation du syndrome PGN chez les urgentistes français. Les symptômes en sont moins importants en post-garde immédiat. Les gardes de traumatologie et de SMUR semblent mieux tolérées.

The phagocytic fitness of leucopatches may impact the healing of chronic wounds

Chronic non-healing wounds are significantly bothersome to patients and can result in severe complications. In addition, they are increasing in numbers, and a challenging problem to the health-care system. Handling of chronic, non-healing wounds can be discouraging due to lack of improvement, and a recent explanation can be the involvement of biofilm infections in the pathogenesis of non-healing wounds. Therefore, new treatment alternatives to improve outcome are continuously sought-after. Autologous leucopatches are such a new, adjunctive treatment option, showing promising clinical effects. However, the beneficial effect of the patches are not understood fully, although a major contribution is believed to be from the release of stimulating growth factors from activated thrombocytes within the leucopatch. Because the leucopatches also contain substantial numbers of leucocytes, the aim of the present study was to investigate the activity of the polymorphonuclear neutrophils (PMNs) within the leucopatch. By means of burst assay, phagocytosis assay, migration assay, biofilm killing assay and fluorescence in-situ hybridization (FISH) assay we showed significant respiratory burst in PMNs, active phagocytosis and killing of Pseudomonas aeruginosa by the leucopatch. In addition, bacterial-induced migration of PMNs from the leucopatch was shown, as well as uptake of P. aeruginosa by PMNs within the leucopatch. The present study substantiated that at least part of the beneficial clinical effect in chronic wounds by leucopatches is attributed to the activity of the PMNs in the leucopatch.

Low efficacy of tobramycin in experimental Staphylococcus aureus endocarditis

The empiric treatment of infective endocarditis (IE) varies widely and, in some places, a regimen of penicillin in combination with an aminoglycoside is administered. The increasing incidence of Staphylococcus aureus IE, poor tissue penetration by aminoglycosides and low frequency of penicillin-susceptible S. aureus may potentially lead to functional tobramycin monotherapy. Therefore, this study aimed to evaluate tobramycin monotherapy in an experimental S. aureus IE rat model. Catheter-induced IE at the aortic valves were established with S. aureus (NCTC 8325-4) and rats were randomised into untreated (n = 22) or tobramycin-treated (n = 13) groups. The treatment group received tobramycin once-daily. Animals were evaluated at 1 day post infection (DPI), 2 DPI or 3 DPI. Quantitative bacteriology and cytokine expression were measured for valves, myocardium and serum. A decrease of bacterial load was observed in valves and the spleens of the treated (n = 6) compared to the untreated group at 2 DPI (n = 8) (p ≤ 0.02 and p ≤ 0.01, respectively), but not at 3 DPI (n = 7). Quantitative bacteriology in the myocardium was not different between the groups. Keratinocyte-derived chemokine (KC) in the aortic valves was significantly reduced at 2 DPI in the tobramycin-treated group (p ≤ 0.03). However, the expression of interleukin (IL)-1b, IL-6 and granulocyte-colony stimulating factor (G-CSF) in the valves was not different between the two groups. In the myocardium, a significant reduction in IL-1b was observed at 2 DPI (p ≤ 0.001) but not at 3 DPI. Tobramycin as functional monotherapy only reduced bacterial load and inflammation transiently, and was insufficient in most cases of S. aureus IE.

Anti-Pseudomonas aeruginosa IgY Antibodies Induce Specific Bacterial Aggregation and Internalization in Human Polymorphonuclear Neutrophils

Polymorphonuclear neutrophils (PMNs) are essential cellular constituents in the innate host response, and their recruitment to the lungs and subsequent ubiquitous phagocytosis controls primary respiratory infection. Cystic fibrosis pulmonary disease is characterized by progressive pulmonary decline governed by a persistent, exaggerated inflammatory response dominated by PMNs. The principal contributor is chronic Pseudomonas aeruginosa biofilm infection, which attracts and activates PMNs and thereby is responsible for the continuing inflammation. Strategies to prevent initial airway colonization with P. aeruginosa by augmenting the phagocytic competence of PMNs may postpone the deteriorating chronic biofilm infection. Anti-P. aeruginosa IgY antibodies significantly increase the PMN-mediated respiratory burst and subsequent bacterial killing of P. aeruginosa in vitro. The mode of action is attributed to IgY-facilitated formation of immobilized bacteria in aggregates, as visualized by fluorescence microscopy and the induction of increased bacterial hydrophobicity. Thus, the present study demonstrates that avian egg yolk immunoglobulins (IgY) targeting P. aeruginosa modify bacterial fitness, which enhances bacterial killing by PMN-mediated phagocytosis and thereby may facilitate a rapid bacterial clearance in airways of people with cystic fibrosis.

Vapor-fed microfluidic hydrogen generator

Water-splitting devices that operate with humid air feeds are an attractive alternative for hydrogen production as the required water input can be obtained directly from ambient air. This article presents a novel proof-of-concept microfluidic platform that makes use of polymeric ion conductor (Nafion®) thin films to absorb water from air and performs the electrochemical water-splitting process. Modelling and experimental tools are used to demonstrate that these microstructured devices can achieve the delicate balance between water, gas, and ionic transport processes required for vapor-fed devices to operate continuously and at steady state, at current densities above 3 mA cm(-2). The results presented here show that factors such as the thickness of the Nafion films covering the electrodes, convection of air streams, and water content of the ionomer can significantly affect the device performance. The insights presented in this work provide important guidelines for the material requirements and device designs that can be used to create practical electrochemical hydrogen generators that work directly under ambient air.

mTOR inhibition improves fibroblast growth factor receptor targeting in hepatocellular carcinoma

Background:

Systemic therapy has proven only marginal effects in hepatocellular carcinoma (HCC) so far. The aim of this study was to evaluate the effect of targeting fibroblast growth factor receptor (FGFR) on tumour and stromal cells in HCC models.

Methods:

Human and murine HCC cells, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), hepatic stellate cells (HSCs), human HCC samples, FGFR inhibitor BGJ398 and mammalian target of rapamycin (mTOR) inhibitor rapamycin were used. Effects on growth, motility, signalling and angiogenic markers were determined. In vivo subcutaneous and syngeneic orthotopic tumour models were used.

Results:

In tumour cells and ECs, targeting FGFR showed significant inhibitory effects on signalling and motility. Minor effects of FGFR inhibition were observed on VSMCs and HSCs, which were significantly enhanced by combining FGFR and mTOR blockade. In vivo daily (5 mg kg⁻¹) treatment with BGJ398 led to a significant growth inhibition in subcutaneous tumour models, but only a combination of FGFR and mTOR blockade impaired tumour growth in the orthotopic model. This was paralleled by reduced tumour cell proliferation, vascularisation, pericytes and increased apoptosis.

Conclusions:

Targeting FGFR with BGJ398 affects tumour cells and ECs, whereas only a combination with mTOR inhibition impairs recruitment of VSMCs and HSCs. Therefore, this study provides evidence for combined FGFR/mTOR inhibition in HCC.

Antidiabetic effects of the Cimicifuga racemosa extract Ze 450 in vitro and in vivo in ob/ob mice

INTRODUCTION

It was the aim of the present experiments to examine potential antidiabetic effects of the Cimicifuga racemosa extract Ze 450.

METHODS

Ze 450 and some of its components (23-epi-26-deoxyactein, protopine and cimiracemoside C) were investigated in vitro for their effects on AMP-activated protein kinase (AMPK) compared to metformin in HepaRG cells. Ze 450 (given orally (PO) and intraperitonally (IP)), metformin (PO) and controls were given over 7 days to 68 male ob/ob mice. Glucose and insulin concentrations were measured at baseline and during an oral glucose tolerance test (OGTT).

RESULTS

Ze 450 and its components activated AMPK to the same extent as metformin. In mice, Ze 450 (PO/IP) decreased significantly average daily and cumulative weight gain, average daily food and water intake, while metformin had no effect. In contrast to metformin, PO Ze 450 virtually did not change maximum glucose levels during OGTT, however, prolonged elimination. Ze 450 administered PO and IP decreased significantly post-stimulated insulin, whereas metformin did not. HOMA-IR index of insulin resistance improved significantly after IP and PO Ze 450 and slightly after metformin. In summary, the results demonstrate that Ze 450 reduced significantly body weight, plasma glucose, improved glucose metabolism and insulin sensitivity in diabetic ob/ob mice. In vitro experiments suggest that part of the effects may be related to AMPK activation.

CONCLUSIONS

Ze 450 may have utility in the treatment of type 2 diabetes. However, longer term studies in additional animal models or patients with disturbed glucose tolerance or diabetes may be of use to investigate this further.

Targeting the actin cytoskeleton: selective antitumor action via trapping PKCɛ

Targeting the actin cytoskeleton (CSK) of cancer cells offers a valuable strategy in cancer therapy. There are a number of natural compounds that interfere with the actin CSK, but the mode of their cytotoxic action and, moreover, their tumor-specific mechanisms are quite elusive. We used the myxobacterial compound Chondramide as a tool to first elucidate the mechanisms of cytotoxicity of actin targeting in breast cancer cells (MCF7, MDA-MB-231). Chondramide inhibits cellular actin filament dynamics shown by a fluorescence-based analysis (fluorescence recovery after photobleaching (FRAP)) and leads to apoptosis characterized by phosphatidylserine exposure, release of cytochrome C from mitochondria and finally activation of caspases. Chondramide enhances the occurrence of mitochondrial permeability transition (MPT) by affecting known MPT modulators: Hexokinase II bound to the voltage-dependent anion channel (VDAC) translocated from the outer mitochondrial membrane to the cytosol and the proapoptotic protein Bad were recruited to the mitochondria. Importantly, protein kinase C-ɛ (PKCɛ), a prosurvival kinase possessing an actin-binding site and known to regulate the hexokinase/VDAC interaction as well as Bad phosphorylation was identified as the link between actin CSK and apoptosis induction. PKCɛ, which was found overexpressed in breast cancer cells, accumulated in actin bundles induced by Chondramide and lost its activity. Our second goal was to characterize the potential tumor-specific action of actin-binding agents. As the nontumor breast epithelial cell line MCF-10A in fact shows resistance to Chondramide-induced apoptosis and notably express low level of PKCɛ, we suggest that trapping PKCɛ via Chondramide-induced actin hyperpolymerization displays tumor cell specificity. Our work provides a link between targeting the ubiquitously occurring actin CSK and selective inhibition of pro-tumorigenic PKCɛ, thus setting the stage for actin-stabilizing agents as innovative cancer drugs. This is moreover supported by the in vivo efficacy of Chondramide triggered by abrogation of PKCɛ signaling shown in a xenograft breast cancer model.

Nitric oxide production by polymorphonuclear leucocytes in infected cystic fibrosis sputum consumes oxygen

Chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients is characterized by persisting mucoid biofilms in hypoxic endobronchial mucus. These biofilms are surrounded by numerous polymorphonuclear leucocytes (PMNs), which consume a major part of present molecular oxygen (O(2)) due to production of superoxide (O(2)(-)). In this study, we show that the PMNs also consume O(2) for production of nitric oxide (NO) by the nitric oxide synthases (NOS) in the infected endobronchial mucus. Fresh expectorated sputum samples (n = 28) from chronically infected CF patients (n = 22) were analysed by quantifying and visualizing the NO production. NO production was detected by optode measurements combined with fluorescence microscopy, flow cytometry and spectrophotometry. Inhibition of nitric oxide synthases (NOS) with N(G) -monomethyl-L-arginine (L-NMMA) resulted in reduced O(2) consumption (P < 0·0008, n = 8) and a lower fraction of cells with fluorescence from the NO-indicator 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM) (P < 0·002, n = 8). PMNs stained with DAF-FM and the superoxide indicator hydroethidine (HE) and host cells with inducible NOS (iNOS) were identified in the sputum. In addition, the production of the stable end-products of NO in CF sputum was correlated with the concentration of PMNs; NO(3)(-) (P < 0·04, r = 0·66, n = 10) and NO(2)(-) (P< 0·006, r = 0·78, n = 11). The present study suggests that besides consumption of O(2) for production of reactive oxygen species, the PMNs in CF sputum also consume O(2) for production of NO.

[Biotechnological therapies for the treatment of back pain: alternatives to corticosteroids]

In recent years, it is increasingly clear that back pain is not only caused by biomechanical problems. Currently, biologically-based local therapy concepts for the treatment of affected spinal regions as an alternative to the standard treatment with steroids are in development or in early stages of clinical application. The common features of these new therapies are to intervene in the regulation of homeostasis at various key points at the affected region and specifically to suppress or block catabolic influences as well as to provide with anti-inflammatory substances and growth factors. These include on one hand the genetically produced Biologicals such as TNF-α inhibitors and cytokine antagonists and on the other hand therapies with autologous blood preparations (Autologous Conditioned Serum [ACS], and Platelet Rich Plasma formulations [PRP]). This article presents the individual methods, gives an overview of developments and results of various studies and discusses current recommendations.

International Spinal Cord Injury Urinary Tract Infection Basic Data Set

OBJECTIVES

To develop an International Spinal Cord Injury (SCI) Urinary Tract Infection (UTI) Basic Data Set presenting a standardized format for the collection and reporting of a minimal amount of information on UTIs in daily practice or research.

SETTING

International working group.

METHODS

The draft of the Data Set developed by a working group was reviewed by the Executive Committee of the International SCI Standards and Data Sets, and later by the International Spinal Cord Society (ISCoS) Scientific Committee and the American Spinal Injury Association (ASIA) Board. Relevant and interested scientific and professional (international) organizations and societies (∼40) were also invited to review the data set, and it was posted on the ISCoS and ASIA websites for 3 months to allow comments and suggestions. The ISCoS Scientific Committee, Executive Committee and ASIA Board received the data set for final review and approval.

RESULTS

The International SCI UTI Basic Data Set includes the following variables: date of data collection, length of time of sign(s)/symptom(s), results of urine dipstick test for nitrite and leukocyte esterase, urine culture results and resistance pattern. The complete instructions for data collection and the data form itself are freely available on the website of ISCoS (http://www.iscos.org.uk).

Bead-size directed distribution of Pseudomonas aeruginosa results in distinct inflammatory response in a mouse model of chronic lung infection

Chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients is characterized by biofilms, tolerant to antibiotics and host responses. Instead, immune responses contribute to the tissue damage. However, this may depend on localization of infection in the upper conductive or in the peripheral respiratory zone. To study this we produced two distinct sizes of small alginate beads (SB) and large beads (LB) containing P. aeruginosa. In total, 175 BALB/c mice were infected with either SB or LB. At day 1 the quantitative bacteriology was higher in the SB group compared to the LB group (P < 0·003). For all time-points smaller biofilms were identified by Alcian blue staining in the SB group (P < 0·003). Similarly, the area of the airways in which biofilms were identified were smaller (P < 0·0001). A shift from exclusively endobronchial to both parenchymal and endobronchial localization of inflammation from day 1 to days 2/3 (P < 0·05), as well as a faster resolution of inflammation at days 5/6, was observed in the SB group (P < 0·03). Finally, both the polymorphonuclear neutrophil leucocyte (PMN) mobilizer granulocyte colony-stimulating factor (G-CSF) and chemoattractant macrophage inflammatory protein-2 (MIP-2) were increased at day 1 in the SB group (P < 0·0001). In conclusion, we have established a model enabling studies of host responses in different pulmonary zones. An effective recognition of and a more pronounced host response to infection in the peripheral zones, indicating that increased lung damage was demonstrated. Therefore, treatment of the chronic P. aeruginosa lung infection should be directed primarily at the peripheral lung zone by combined intravenous and inhalation antibiotic treatment.

Thermal phase change actuator for self-tracking solar concentration

We present a proof of principle demonstration of a reversible in-plane actuator activated by focused sunlight, and describe a concept for its use as a self-tracking mechanism in a planar solar concentrator. By actuating at the location of focused sunlight and splitting the solar spectrum for actuation energy, this phase change device aims to provide the adaptive mechanism necessary to efficiently couple concentrated solar light from a lens into a planar lightguide in a manner that is insensitive to incidence angle. As a preliminary demonstration we present a planar actuator array capable of in-plane deflections of >50 μm when illuminated with focused light from a solar simulator and demonstrate solar light activated frustrated total internal reflection (FTIR) with the actuator array. We further propose how this solar induced FTIR effect can be modified using a dichroic facet array to self-adaptively couple and concentrate solar light into a planar lightguide.

Thermal phase change actuator for self-tracking solar concentration

We present a proof of principle demonstration of a reversible in-plane actuator activated by focused sunlight, and describe a concept for its use as a self-tracking mechanism in a planar solar concentrator. By actuating at the location of focused sunlight and splitting the solar spectrum for actuation energy, this phase change device aims to provide the adaptive mechanism necessary to efficiently couple concentrated solar light from a lens into a planar lightguide in a manner that is insensitive to incidence angle. As a preliminary demonstration we present a planar actuator array capable of in-plane deflections of >50μm when illuminated with focused light from a solar simulator and demonstrate solar light activated frustrated total internal reflection (FTIR) with the actuator array. We further propose how this solar induced FTIR effect can be modified using a dichroic facet array to self-adaptively couple and concentrate solar light into a planar lightguide.

[A smoking cessation intervention in the Swiss Armed Forces]

Smoking is a major health risk in young adults. We undertook a study in young Swiss military recruits to determine the impact of intensive training and of help offered on smoking cessation during Basic Military Training (BMT). A questionnaire including questions according to their smoking status, sporting activities and, alcohol use was administered to 999 conscripts at beginning and at the end of the BMT. The results were compared to a control group of BMT schools where no such intervention took place. The study shows that the prevalence of smokers in the intervention group decreased (start BMT 31.9%, end BMT 25.5%; p = 0.021), while the prevalence of smokers increased in the control group (start BMT 26.4%, end BMT 32.6%; p = 0.038). A motivation to serve in the armed forces, as well as the willingness to stop smoking in the next month were the factors associated with a subsequent cessation of smoking during BMT. A smoke stop intervention during BMT is viable and can lead to a decrease in the prevalence of smoking at the end of BMT.

Genetic correlation in relation to differences in dosage of a stressor

We exposed the strains of Chlamydomonas isolated from an outbred laboratory population to a range of concentrations of salt (NaCl) up to an extirpative level that the base population could not tolerate. The genetic variance of yield increased with stress over the first half of this range before collapsing to nearly zero. The genetic correlation decreased with environmental distance, whether measured as a difference in dosage or as an environmental variance. This result is consistent with previous studies and provides a basis for interpreting adaptation to a deteriorating environment and the process of evolutionary rescue.

Austrian syndrome

The authors present a case of Austrian syndrome, the triad of pneumococcal pneumonia, endocarditis and meningitis, in a 49-year-old woman, who developed severe acute heart failure due to aortic valve destruction. The patient required imminent valve surgery, but eventually recovered.