Measurement of length distribution of beta-lactoglobulin fibrils by multiwavelength analytical ultracentrifugation

The whey protein beta-lactoglobulin is the building block of amyloid fibrils which exhibit a great potential in various applications. These include stabilization of gels or emulsions. During biotechnological processing, high shear forces lead to fragmentation of fibrils and therefore to smaller fibril lengths. To provide insight into such processes, pure straight amyloid fibril dispersions (prepared at pH 2) were produced and sheared using the rotor stator setup of an Ultra Turrax. In the first part of this work, the sedimentation properties of fragmented amyloid fibrils sheared at different stress levels were analyzed with mulitwavelength analytical ultracentrifugation (AUC). Sedimentation data analysis was carried out with the boundary condition that fragmented fibrils were of cylindrical shape, for which frictional properties are known. These results were compared with complementary atomic force microscopy (AFM) measurements. We demonstrate how the sedimentation coefficient distribution from AUC experiments is influenced by the underlying length and diameter distribution of amyloid fibrils. In the second part of this work, we show how to correlate the fibril size reduction kinetics with the applied rotor revolution and the resulting energy density, respectively, using modal values of the sedimentation coefficients obtained from AUC. Remarkably, the determined scaling laws for the size reduction are in agreement with the results for other material systems, such as emulsification processes or the size reduction of graphene oxide sheets.</p

Rethinking energy, climate and security: a critical analysis of energy security in the US

Understanding the complicated relationship between energy, climate and security is vital both to the study of international relations and to ensure the continued survival of a world increasingly threatened by environmental change. Climate change is largely caused by burning fossil fuels for energy, but while discussions on the climate consider the role of energy, energy security debates largely overlook climate concerns. This article traces the separation between energy and climate through an analysis of US energy security discourse and policy. It shows that energy security is continually constructed as national security, which enables very particular policy choices and prioritises it above climate concerns. Thus, in many cases, policies undertaken in the name of energy security contribute directly to climate insecurity. The article argues that the failure to consider securing the climate as inherently linked to energy security is not just problematic, but, given global warming, potentially harmful. Consequently, any approach to dealing with climate change has to begin by rethinking energy security and security more broadly, as national (energy) security politics no longer provides security in any meaningful sense

Identification of patients at high risk for brain death using an automated digital screening tool: a prospective diagnostic accuracy study

Background An automated digital screening tool (DETECT) has been developed to aid in the early identification of patients who are at risk of developing brain death during critical care. Methods This prospective diagnostic accuracy study included consecutive patients ≥ 18 years admitted to neurocritical care for primary or secondary acute brain injury. The DETECT screening tool searched routinely monitored patient data in the electronic medical records every 12 h for a combination of coma and absence of bilateral pupillary light reflexes. In parallel, daily neurological assessment was performed by expert neurointensivists in all patients blinded to the index test results. The primary target condition was the eventual diagnosis of brain death. Estimates of diagnostic accuracy along with their 95%-confidence intervals were calculated to assess the screening performance of DETECT. Results During the 12-month study period, 414 patients underwent neurological assessment, with 8 (1.9%) confirmed cases of brain death. DETECT identified 54 positive patients and sent 281 notifications including 227 repeat notifications. The screening tool had a sensitivity of 100% (95% CI 63.1–100%) in identifying patients who eventually developed brain death, with no false negatives. The mean time from notification to confirmed diagnosis of brain death was 3.6 ± 3.2 days. Specificity was 88.7% (95% CI 85.2–91.6%), with 46 false positives. The overall accuracy of DETECT for confirmed brain death was 88.9% (95% CI 85.5–91.8%). Conclusions Our findings suggest that an automated digital screening tool that utilizes routinely monitored clinical data may aid in the early identification of patients at risk of developing brain death

Team Prenotification Reduces Procedure Times for Patients With Acute Ischemic Stroke Due to Large Vessel Occlusion Who Are Transferred for Endovascular Therapy

Background: The clinical benefit from endovascular therapy (EVT) for patients with acute ischemic stroke is time-dependent. We tested the hypothesis that team prenotification results in faster procedure times prior to initiation of EVT. Methods: We analyzed data from our prospective database (01/2016–02/2018) including all patients with acute ischemic stroke who were evaluated for EVT at our comprehensive stroke center. We established a standardized algorithm (EVT-Call) in 06/2017 to prenotify team members (interventional neuroradiologist, neurologist, anesthesiologist, CT and angiography technicians) about patient transfer from remote hospitals for evaluation of EVT, and team members were present in the emergency department at the expected patient arrival time. We calculated door-to-image, image-to-groin and door-to-groin times for patients who were transferred to our center for evaluation of EVT, and analyzed changes before (–EVT-Call) and after (+EVT-Call) implementation of the EVT-Call. Results: Among 494 patients in our database, 328 patients were transferred from remote hospitals for evaluation of EVT (208 -EVT-Call and 120 +EVT-Call, median [IQR] age 75 years [65–81], NIHSS score 17 [12–22], 49.1% female). Of these, 177 patients (54%) underwent EVT after repeated imaging at our center (111/208 [53%) -EVT-Call, 66/120 [55%] +EVT-Call). Median (IQR) door-to-image time (18 min [14–22] vs. 10 min [7–13]; p < 0.001), image-to-groin time (54 min [43.5–69.25] vs. 47 min [38.3–58.75]; p = 0.042) and door-to-groin time (74 min [58–86.5] vs. 60 min [49.3–71]; p < 0.001) were reduced after implementation of the EVT-Call. Conclusions: Team prenotification results in faster patient assessment and initiation of EVT in patients with acute ischemic stroke. Its impact on functional outcome needs to be determined

Measurement of length distribution of beta-lactoglobulin fibrils by multiwavelength analytical ultracentrifugation

Abstract The whey protein beta-lactoglobulin is the building block of amyloid fibrils which exhibit a great potential in various applications. These include stabilization of gels or emulsions. During biotechnological processing, high shear forces lead to fragmentation of fibrils and therefore to smaller fibril lengths. To provide insight into such processes, pure straight amyloid fibril dispersions (prepared at pH 2) were produced and sheared using the rotor stator setup of an Ultra Turrax. In the first part of this work, the sedimentation properties of fragmented amyloid fibrils sheared at different stress levels were analyzed with mulitwavelength analytical ultracentrifugation (AUC). Sedimentation data analysis was carried out with the boundary condition that fragmented fibrils were of cylindrical shape, for which frictional properties are known. These results were compared with complementary atomic force microscopy (AFM) measurements. We demonstrate how the sedimentation coefficient distribution from AUC experiments is influenced by the underlying length and diameter distribution of amyloid fibrils. In the second part of this work, we show how to correlate the fibril size reduction kinetics with the applied rotor revolution and the resulting energy density, respectively, using modal values of the sedimentation coefficients obtained from AUC. Remarkably, the determined scaling laws for the size reduction are in agreement with the results for other material systems, such as emulsification processes or the size reduction of graphene oxide sheets

Low Diagnostic Yield of Routine Cerebrospinal Fluid Analysis in Juvenile Stroke

Background: The diagnostic value of cerebrospinal fluid (CSF) analysis in juvenile stroke, i.e., stroke in young adult patients, is not well studied. We sought to determine the therapeutic impact of routine CSF-analysis in young adults with acute ischemic stroke or transient ischemic attack (TIA).Methods: We abstracted data from patients with acute cerebral ischemia aged 18–45 years who were consecutively admitted to our stroke center between 01/2008 and 12/2015. We routinely performed CSF-analysis in patients with hitherto unknown stroke etiology after complete diagnostic work up. We assessed the frequency and underlying causes of abnormal CSF-findings and their impact on secondary stroke prevention therapy.Results: Among 379 patients (median [IQR:IQR3-IQR1] age 39 [10:43-33] years, 48% female) with acute ischemic stroke (n = 306) or TIA (n = 73), CSF analysis was performed in 201 patients (53%). Of these, 25 patients (12.4 %) had CSF pleocytosis (leucocyte cell count ≥ 5 Mpt/L), that was rated as non-specific (e.g., traumatic lumbar puncture, reactive pleocytosis) in 22 patients. Only 3 patients (1.5% of all patients who underwent CSF-analysis) with CSF-pleocytosis had specific CSF-findings that were related to stroke etiology and affected secondary stroke prevention therapy. Imaging findings had already suggested cerebral vasculitis in two of these patients.Conclusions: The diagnostic yield of routine CSF-analysis in juvenile stroke was remarkably low in our study. Our data suggest that CSF-analysis should only be performed if further findings raise the suspicion of cerebral vasculitis

Transcriptomic analysis reveals a global alkyl-quinolone-independent regulatory role for PqsE in facilitating the environmental adaptation of Pseudomonas aeruginosa to plant and animal hosts

The quorum sensing (QS) system of Pseudomonas aeruginosa constitutes a sophisticated genome-wide gene regulatory network employing both N-acylhomoserine lactone and 2-alkyl-4-quinolone (AQ) signal molecules. AQ signalling utilizes 2-heptyl-3-hydroxy-4-quinolone (PQS) and its immediate precursor, 2-heptyl-4-quinolone (HHQ). AQ biosynthesis requires the first four genes of the pqsABCDE operon and while the biochemical function of pqsE is not known, it is required for the production of secondary metabolites such as pyocyanin. To gain insights into the relationship between the AQ stimulon, the PqsE stimulon and the regulatory function of PqsE, we constructed a pqsE inducible mutant (pqsEind) and compared the transcriptomes of the induced and uninduced states with a pqsA mutant. Of 158 genes exhibiting altered expression in the pqsA mutant, 51% were also affected in the pqsE mutant. Following induction of pqsE, 237 genes were differentially expressed compared with the wild-type strain. In the pqsEind strain, pqsA was highly expressed but following induction both pqsA expression and AQ biosynthesis were repressed, revealing a negative autoregulatory role for PqsE. Furthermore, pqsE was required for swarming motility and virulence in plant and animal infection models in the absence of AQs, while mature biofilm development required both pqsA and pqsE. Taken together these data reveal that PqsE is a key regulator within the QS circuitry facilitating the environmental adaptation of P. aeruginosa

The luxS mutation causes loosely-bound biofilms in Shewanella oneidensis

<p>Abstract</p> <p>Background</p> <p>The <it>luxS </it>gene in <it>Shewanella oneidensis </it>was shown to encode an autoinducer-2 (AI-2)-like molecule, the postulated universal bacterial signal, but the impaired biofilm growth of a <it>luxS </it>deficient mutant could not be restored by AI-2, indicating it might not have a signalling role in this organism.</p> <p>Findings</p> <p>Here, we provide further evidence regarding the metabolic role of a <it>luxS </it>mutation in <it>S. oneidensis</it>. We constructed a <it>luxS </it>mutant and compared its phenotype to a wild type control with respect to its ability to remove AI-2 from the medium, expression of secreted proteins and biofilm formation. We show that <it>S. oneidensis </it>has a cell-dependent mechanism by which AI-2 is depleted from the medium by uptake or degradation at the end of the exponential growth phase. As AI-2 depletion is equally active in the <it>luxS </it>mutant and thus does not require AI-2 as an inducer, it appears to be an unspecific mechanism suggesting that AI-2 for <it>S. oneidensis </it>is a metabolite which is imported under nutrient limitation. Secreted proteins were studied by iTraq labelling and liquid chromatography mass spectrometry (LC-MS) detection. Differences between wild type and mutant were small. Proteins related to flagellar and twitching motility were slightly up-regulated in the <it>luxS </it>mutant, in accordance with its loose biofilm structure. An enzyme related to cysteine metabolism was also up-regulated, probably compensating for the lack of the LuxS enzyme. The <it>luxS </it>mutant developed an undifferentiated, loosely-connected biofilm which covered the glass surface more homogenously than the wild type control, which formed compact aggregates with large voids in between.</p> <p>Conclusions</p> <p>The data confirm the role of the LuxS enzyme for biofilm growth in <it>S. oneidensis </it>and make it unlikely that AI-2 has a signalling role in this organism.</p

Endovascular Therapy in the Extended Time Window for Large Vessel Occlusion in Patients With Pre-Stroke Disability.

BACKGROUND AND PURPOSE We compared the outcomes of endovascular therapy (EVT) in an extended time window in patients with large-vessel occlusion (LVO) between patients with and without pre-stroke disability. METHODS In this prespecified analysis of the multinational CT for Late Endovascular Reperfusion study (66 participating sites, 10 countries between 2014 and 2022), we analyzed data from patients with acute ischemic stroke with a pre-stroke modified Rankin Scale (mRS) score of 0-4 and LVO who underwent EVT 6-24 hours from the time last seen well. The primary outcome was the composite of functional independence (FI; mRS score 0-2) or return to the pre-stroke mRS score (return of Rankin, RoR) at 90 days. Outcomes were compared between patients with pre-stroke disability (pre-stroke mRS score 2-4) and those without (mRS score 0-1). RESULTS A total of 2,231 patients (median age, 72 years; median National Institutes of Health Stroke Scale score, 16) were included in the present analysis. Of these, 564 (25%) had pre-stroke disability. The primary outcome (FI or RoR) was observed in 30.7% of patients with pre-stroke disability (FI, 16.5%; RoR, 30.7%) compared to 44.1% of patients without (FI, 44.1%; RoR, 13.0%) (P<0.001). In multivariable logistic regression analysis with inverse probability of treatment weighting, pre-stroke disability was not associated with significantly lower odds of achieving FI or RoR (adjusted odds ratio 0.73, 95% confidence interval 0.43-1.25). Symptomatic intracranial hemorrhage occurred in 6.3% of both groups (P=0.995). CONCLUSION A considerable proportion of patients with late-presenting LVO and pre-stroke disability regained pre-stroke mRS scores after EVT. EVT may be appropriate for patients with pre-stroke disability presenting in the extended time window