The type-I interferon response potentiates seeded tau aggregation and exacerbates tau pathology.

INTRODUCTION: Signatures of a type-I interferon (IFN-I) response are observed in the post mortem brain in Alzheimer's disease (AD) and other tauopathies. However, the effect of the IFN-I response on pathological tau accumulation remains unclear. METHODS: We examined the effects of IFN-I signaling in primary neural culture models of seeded tau aggregation and P301S-tau transgenic mouse models in the context of genetic deletion of the IFN-I receptor (IFNAR). RESULTS: Polyinosinic:polycytidylic acid (PolyI:C), a synthetic analog of viral nucleic acids, evoked a potent cytokine response that enhanced seeded aggregation of tau in an IFN-I-dependent manner. IFN-I-induced vulnerability could be pharmacologically prevented and was intrinsic to neurons. Aged P301S-tau mice lacking Ifnar1 had significantly reduced tau pathology compared to mice with intact IFN signaling. DISCUSSION: We identify a critical role for IFN-I in potentiating tau aggregation. IFN-I is therefore identified as a potential therapeutic target in AD and other tauopathies. HIGHLIGHTS: Type-I IFN (IFN-I) promotes seeded tau aggregation in neural cultures. IFNAR inhibition prevents IFN-I driven sensitivity to tau aggregation. IFN-I driven vulnerability is intrinsic to neurons. Tau pathology is significantly reduced in aged P301S-tau mice lacking IFNAR.

Use of Dexmedetomidine During an Emergent Exploratory Laparotomy in a High-Risk Cardiac Patient With an Intra-aortic Balloon Pump.

An intra-aortic balloon pump (IABP) may be placed preoperatively for high-risk patients with reduced ejection fraction or multivessel coronary disease undergoing non-cardiac surgery. Dexmedetomidine (DEX) has both anesthetic and cardioprotective effects, and little evidence is present on its effect on minimum alveolar concentration (MAC) and bispectral index (BIS). We present the case of a high-risk cardiac patient who was admitted and required fluid optimization prior to coronary artery bypass grafting (CABG). An IABP was placed after failure to tolerate intermittent hemodialysis (iHD). Bowel ischemia complicated this patient's course, necessitating an urgent exploratory laparotomy with the IABP in place. DEX and 0.3-MAC sevoflurane were successfully used without perioperative cardiac complications. Continuous BIS monitoring was performed to maintain an adequate level of anesthesia. DEX should be considered as an alternative anesthetic adjuvant in high-risk and medically complex patients.

Super-resolution imaging unveils the self-replication of tau aggregates upon seeding.

Tau is a soluble protein interacting with tubulin to stabilize microtubules. However, under pathological conditions, it becomes hyperphosphorylated and aggregates, a process that can be induced by treating cells with exogenously added tau fibrils. Here, we employ single-molecule localization microscopy to resolve the aggregate species formed in early stages of seeded tau aggregation. We report that entry of sufficient tau assemblies into the cytosol induces the self-replication of small tau aggregates, with a doubling time of 5 h inside HEK cells and 1 day in murine primary neurons, which then grow into fibrils. Seeding occurs in the vicinity of the microtubule cytoskeleton, is accelerated by the proteasome, and results in release of small assemblies into the media. In the absence of seeding, cells still spontaneously form small aggregates at lower levels. Overall, our work provides a quantitative picture of the early stages of templated seeded tau aggregation in cells.

Perforin-2 is a pore-forming effector of endocytic escape in cross-presenting dendritic cells.

During initiation of antiviral and antitumor T cell-mediated immune responses, dendritic cells (DCs) cross-present exogenous antigens on major histocompatibility complex (MHC) class I molecules. Cross-presentation relies on the unusual "leakiness" of endocytic compartments in DCs, whereby internalized proteins escape into the cytosol for proteasome-mediated generation of MHC I-binding peptides. Given that type 1 conventional DCs excel at cross-presentation, we searched for cell type-specific effectors of endocytic escape. We devised an assay suitable for genetic screening and identified a pore-forming protein, perforin-2 (Mpeg1), as a dedicated effector exclusive to cross-presenting cells. Perforin-2 was recruited to antigen-containing compartments, where it underwent maturation, releasing its pore-forming domain. Mpeg1-/- mice failed to efficiently prime CD8+ T cells to cell-associated antigens, revealing an important role for perforin-2 in cytosolic entry of antigens during cross-presentation.

Effect of cetrimonium carrier micelles on bacterial membranes and extracellular DNA, an in silico study.

Microorganisms do not live as dispersed single cells but rather they form aggregates with extracellular polymeric substances at interfaces. Biofilms are considered efficient life forms because they shield bacteria from biocides and collect dilute nutrients. This is a big concern in industry since the microorganisms can colonize a wide range of surfaces, accelerating material deterioration, colonizing medical devices, contaminating ultrapure drinking water, increasing energy costs and creating focus of infection. Conventional biocides that target a specific component of the bacteria are not effective in the presence of biofilms. Efficient biofilm inhibitors are based on a multitarget approach interacting with the bacteria and the biofilm matrix. Their rationale design requires a thorough understanding of inhibitory mechanisms that are still largely lacking today. Herein we uncover via molecular modelling the inhibition mechanism of cetrimonium 4-OH cinnamate (CTA-4OHcinn). Simulations show that CTA-4OH micelles can disrupt symmetric and asymmetric bilayers, representative of inner and outer bacterial membranes, following three stages: adsorption, assimilation, and defect formation. The main driving force for micellar attack is electrostatic interactions. In addition to disrupting the bilayers, the micelles work as carriers facilitating the trapping of 4OH cinnamate anions within the bilayer upper leaflet and overcoming electrostatic repulsion. The micelles also interact with extracellular DNA (e-DNA), which is one of the main components of biofilms. It is observed that CTA-4OHcinn forms spherical micelles on the DNA backbone; which hinders their ability to pack. This is demonstrated by modelling the DNA along the hbb histone-like protein, showing that in the presence of CTA-4OHcinn, DNA does not pack properly around hbb. The abilities of CTA-4OHcinn to cause cell death through membrane disruption and to disperse a mature, multi-species biofilm are also confirmed experimentally.

Cytosolic antibody receptor TRIM21 is required for effective tau immunotherapy in mouse models.

Aggregates of the protein tau are proposed to drive pathogenesis in neurodegenerative diseases. Tau can be targeted by using passively transferred antibodies (Abs), but the mechanisms of Ab protection are incompletely understood. In this work, we used a variety of cell and animal model systems and showed that the cytosolic Ab receptor and E3 ligase TRIM21 (T21) could play a role in Ab protection against tau pathology. Tau-Ab complexes were internalized to the cytosol of neurons, which enabled T21 engagement and protection against seeded aggregation. Ab-mediated protection against tau pathology was lost in mice that lacked T21. Thus, the cytosolic compartment provides a site of immunotherapeutic protection, which may help in the design of Ab-based therapies in neurodegenerative disease.

Extracellular DNA: A Critical Aspect of Marine Biofilms.

Multispecies biofilms represent a pervasive threat to marine-based industry, resulting in USD billions in annual losses through biofouling and microbiologically influenced corrosion (MIC). Biocides, the primary line of defence against marine biofilms, now face efficacy and toxicity challenges as chemical tolerance by microorganisms increases. A lack of fundamental understanding of species and EPS composition in marine biofilms remains a bottleneck for the development of effective, target-specific biocides with lower environmental impact. In the present study, marine biofilms are developed on steel with three bacterial isolates to evaluate the composition of the EPSs (extracellular polymeric substances) and population dynamics. Confocal laser scanning microscopy, scanning electron microscopy, and fluorimetry revealed that extracellular DNA (eDNA) was a critical structural component of the biofilms. Parallel population analysis indicated that all three strains were active members of the biofilm community. However, eDNA composition did not correlate with strain abundance or activity. The results of the EPS composition analysis and population analysis reveal that biofilms in marine conditions can be stable, well-defined communities, with enabling populations that shape the EPSs. Under marine conditions, eDNA is a critical EPS component of the biofilm and represents a promising target for the enhancement of biocide specificity against these populations.

Enhancing Biocide Efficacy: Targeting Extracellular DNA for Marine Biofilm Disruption.

Biofilm formation is a global health, safety and economic concern. The extracellular composition of deleterious multispecies biofilms remains uncanvassed, leading to an absence of targeted biofilm mitigation strategies. Besides economic incentives, drive also exists from industry and research to develop and apply environmentally sustainable chemical treatments (biocides); especially in engineered systems associated with the marine environment. Recently, extracellular DNA (eDNA) was implicated as a critical structural polymer in marine biofilms. Additionally, an environmentally sustainable, multi-functional biocide was also introduced to manage corrosion and biofilm formation. To anticipate biofilm tolerance acquisition to chemical treatments and reduce biocide application quantities, the present research investigated eDNA as a target for biofilm dispersal and potential enhancement of biocide function. Results indicate that mature biofilm viability can be reduced by two-fold using reduced concentrations of the biocide alone (1 mM instead of the recommended 10 mM). Importantly, through the incorporation of an eDNA degradation stage, biocide function could be enhanced by a further ~90% (one further log reduction in viability). Biofilm architecture analysis post-treatment revealed that endonuclease targeting of the matrix allowed greater biocide penetration, leading to the observed viability reduction. Biofilm matrix eDNA is a promising target for biofilm dispersal and antimicrobial enhancement in clinical and engineered systems.

Cholesterol determines the cytosolic entry and seeded aggregation of tau.

Assemblies of tau can transit between neurons, seeding aggregation in a prion-like manner. To accomplish this, tau must cross cell-limiting membranes, a process that is poorly understood. Here, we establish assays for the study of tau entry into the cytosol as a phenomenon distinct from uptake, in real time, and at physiological concentrations. The entry pathway of tau is cell type specific and, in neurons, highly sensitive to cholesterol. Depletion of the cholesterol transporter Niemann-Pick type C1 or extraction of membrane cholesterol renders neurons highly permissive to tau entry and potentiates seeding even at low levels of exogenous tau assemblies. Conversely, cholesterol supplementation reduces entry and almost completely blocks seeded aggregation. Our findings establish entry as a rate-limiting step to seeded aggregation and demonstrate that dysregulated cholesterol, a feature of several neurodegenerative diseases, potentiates tau aggregation by promoting entry of tau assemblies into the cell interior.

Conditioning of metal surfaces enhances Shewanella chilikensis adhesion.

Microbiologically influenced corrosion and biofouling of steels depend on the adsorption of a conditioning film and subsequent attachment of bacteria. Extracellular deoxyribonucleic acid (eDNA) and amino acids are biologically critical nutrient sources and are ubiquitous in marine environments. However, little is known about their role as conditioning film molecules in early biofilm formation on metallic surfaces. The present study evaluated the capacity for eDNA and amino acids to form a conditioning film on carbon steel (CS), and subsequently, the influence of these conditioning films on bacterial attachment using a marine bacterial strain. Conditioning films of eDNA or amino acids were formed on CS through physical adsorption. Biochemical and microscopic analysis of eDNA conditioning, amino acid conditioning and control CS surfaces demonstrated that organic conditioning surfaces promoted bacterial attachment. The results highlight the importance of conditioning the surface in initial bacterial attachment to steel.

Efficiency of a Novel Multifunctional Corrosion Inhibitor Against Biofilms Developed on Carbon Steel.

In natural environments, populations of microorganisms rapidly colonise surfaces forming biofilms. These sessile communities comprise a variety of species which contribute to biofouling and microbiologically influenced corrosion (MIC), especially on metals. Species heterogeneity in natural systems confers higher tolerance to adverse conditions such as biocide treatment compared with single species laboratory simulations. Effective chemical treatments to combat recalcitrant biofilms are often dangerous to apply; both to operators and the environment, and face international embargoes. Today, there is a drive to exchange current toxic and environmentally hazardous biocides with less harmful compounds. One effective method of achieving this goal is to generate multi-functional compounds capable of tackling corrosion and biofilm formation simultaneously, thus reducing the number of compounds in dosing procedures. In a previous study, a novel corrosion inhibitor demonstrated biocidal effects against three marine isolates during the early stages of biofilm formation. The compound; CTA-4OHcinn, holds great promise as a multi-functional inhibitor, however its effect on complex, multi-species biofilms remains unknown. Here we evaluate CTA-4OHcinn biocidal capacity against multi-species biofilms developed from oilfield samples. Mature biofilms were developed and treated with 10 mM CTA-4OHcinn for 4 h. The effects of the compound were assessed using mean probable number (MPN), adenosine triphosphate (ATP) quantification, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Results demonstrate that CTA-4OHcinn significantly reduces the viability of mature biofilms, supporting previous demonstrations on the secondary function of CTA-4OHcinn as a biocide. CLSM results further indicate that CTA-4OHcinn targets the cell membrane resulting in lysis. This finding complements the established corrosion inhibition function of CTA-4OHcinn, indicating the compound is a true multi-functional organic corrosion inhibitor.

Evaluation of a novel, multi-functional inhibitor compound for prevention of biofilm formation on carbon steel in marine environments.

Chemical biocides remain the most effective mitigation strategy against microbiologically influenced corrosion (MIC), one of the costliest and most pervasive forms of corrosion in industry. However, toxicity and environmental concerns associated with these compounds are encouraging the development of more environmentally friendly MIC inhibitors. In this study, we evaluated the antimicrobial effect of a novel, multi-functional organic corrosion inhibitor (OCI) compound, cetrimonium trans-4-hydroxy-cinnamate (CTA-4OHcinn). Attachment of three bacterial strains, Shewanella chilikensis, Pseudomonas balearica and Klebsiella pneumoniae was evaluated on wet-ground (120 grit finish) and pre-oxidised carbon steel surfaces (AISI 1030), in the presence and absence of the new OCI compound. Our study revealed that all strains preferentially attached to pre-oxidised surfaces as indicated by confocal laser scanning microscopy, scanning electron microscopy and standard colony forming unit (CFU) quantification assays. The inhibitor compound at 10 mM demonstrated 100% reduction in S. chilikensis attachment independent of initial surface condition, while the other two strains were reduced by at least 99.7% of the original viable cell number. Our results demonstrate that CTA-4OHcinn is biocidal active and has promise as a multifunctional, environmentally sound MIC inhibitor for industrial applications.

Tau assemblies do not behave like independently acting prion-like particles in mouse neural tissue.

A fundamental property of infectious agents is their particulate nature: infectivity arises from independently-acting particles rather than as a result of collective action. Assemblies of the protein tau can exhibit seeding behaviour, potentially underlying the apparent spread of tau aggregation in many neurodegenerative diseases. Here we ask whether tau assemblies share with classical pathogens the characteristic of particulate behaviour. We used organotypic hippocampal slice cultures from P301S tau transgenic mice in order to precisely control the concentration of extracellular tau assemblies in neural tissue. Whilst untreated slices displayed no overt signs of pathology, exposure to recombinant tau assemblies could result in the formation of intraneuronal, hyperphosphorylated tau structures. However, seeding ability of tau assemblies did not titrate in a one-hit manner in neural tissue. The results suggest that seeding behaviour of tau arises at high concentrations, with implications for the interpretation of high-dose intracranial challenge experiments and the possible contribution of seeded aggregation to human disease.

The Role of Antibodies and Their Receptors in Protection Against Ordered Protein Assembly in Neurodegeneration.

Ordered assemblies of proteins are found in the postmortem brains of sufferers of several neurodegenerative diseases. The cytoplasmic microtubule associated protein tau and alpha-synuclein (αS) are found in an assembled state in Alzheimer's disease and Parkinson's disease, respectively. An accumulating body of evidence suggests a "prion-like" mechanism of spread of these assemblies through the diseased brain. Under this hypothesis, assembled variants of these proteins promote the conversion of native proteins to the assembled state. This likely inflicts pathology on cells of the brain through a toxic gain-of-function mechanism. Experiments in animal models of tau and αS pathology have demonstrated that the passive transfer of anti-tau or anti-αS antibodies induces a reduction in the levels of assembled proteins. This is further accompanied by improvements in neurological function and preservation of brain volume. Immunotherapy is therefore considered one of the brightest hopes as a therapeutic avenue in an area currently without disease-modifying therapy. Following a series of disappointing clinical trials targeting beta-amyloid, a peptide that accumulates in the extracellular spaces of the AD brain, attention is turning to active and passive immunotherapies that target tau and αS. However, there are several remaining uncertainties concerning the mechanism by which antibodies afford protection against self-propagating protein conformations. This review will discuss current understanding of how antibodies and their receptors can be brought to bear on proteins involved in neurodegeneration. Parallels will be made to antibody-mediated protection against classical viral infections. Common mechanisms that may contribute to protection against self-propagating protein conformations include blocking the entry of protein "seeds" to cells, clearance of immune complexes by microglia, and the intracellular protein degradation pathway initiated by cytoplasmic antibodies via the Fc receptor TRIM21. As with anti-viral immunity, protective mechanisms may be accompanied by the activation of immune signaling pathways and we will discuss the suitability of such activation in the neurological setting.

Clinical Update in Pericardial Diseases.

Patients with pericardial disease often require interventional therapies or surgery, making it essential for anesthesiologists to understand the altered physiology of these disease states and the resultant impact on perioperative management. The broad spectrum of syndromes involving the pericardium present with varying degrees of clinical significance, from asymptomatic presentations to life-threatening emergencies. Impaired diastolic filling of the heart represents a common theme of pericardial disease, with the rate of onset of pericardial pathology largely determining the extent of this impairment and subsequent severity of presentation. This review highlights recent updates in the literature regarding the diagnostic evaluation, medical therapy, and invasive therapeutic procedures for common pericardial syndromes from the perspective of a perioperative physician.

The role of transesophageal echocardiography in the management of renal cell carcinoma with venous tumor thrombus.

We reviewed the role of transesophageal echocardiography (TEE) in the management of renal cell carcinoma (RCC) with associated tumor thrombus. Many consider intraoperative TEE as imperative in cases of Level 4 thrombi with atrial involvement, as well as in cases that require the use of cardiopulmonary bypass (CPB). However, the role of TEE in the surgical management of RCC with associated inferior vena cava (IVC) thrombus may expand beyond this subset. When performed after induction, TEE provides updated information regarding tumor thrombus staging, which is essential for optimal surgical planning. Furthermore, TEE provides feedback regarding properties of the thrombus, such as fragility and adherence, which may alter surgical technique. TEE can also be used intraoperatively for central venous line placement, to monitor cardiovascular and fluid status, to guide vascular clamp placement, and to ensure complete removal of the tumor thrombus. In some cases, the use of TEE allows for less morbid procedures and safe avoidance of CPB. We therefore recommend the use of preoperative TEE in all cases with a known tumor thrombus with discretion as to what extent TEE is used throughout the remainder of the case. Further investigation is necessary to elucidate the effect of TEE on patient outcomes, including surgical complication rates, morbidity and mortality of procedures, and cancer control.