11 research outputs found
Comparing and Combining Capillary Electrophoresis Electrospray Ionization Mass Spectrometry and Nano-Liquid Chromatography Electrospray Ionization Mass Spectrometry for the Characterization of Post-translationally Modified Histones
No full text
Defining the Surface Oxygen Threshold That Switches the Interaction Mode of Graphene Oxide with Bacteria
No full textAs antimicrobials, graphene materials (GMs) may have
advantages
over traditional antibiotics due to their physical mechanisms of action
which ensure less chance of development of microbial resistance. However,
the fundamental question as to whether the antibacterial mechanism
of GMs originates from parallel interaction or perpendicular interaction,
or from a combination of these, remains poorly understood. Here, we
show both experimentally and theoretically that GMs with high surface
oxygen content (SOC) predominantly attach in parallel to the bacterial
cell surface when in the suspension phase. The interaction mode shifts
to perpendicular interaction when the SOC reaches a threshold of ∼0.3
(the atomic percent of O in the total atoms). Such distinct interaction
modes are highly related to the rigidity of GMs. Graphene oxide (GO)
with high SOC is very flexible and thus can wrap bacteria while reduced
GO (rGO) with lower SOC has higher rigidity and tends to contact bacteria
with their edges. Neither mode necessarily kills bacteria. Rather,
bactericidal activity depends on the interaction of GMs with surrounding
biomolecules. These findings suggest that variation of SOC of GMs
is a key factor driving the interaction mode with bacteria, thus helping
to understand the different possible physical mechanisms leading to
their antibacterial activity
Patient satisfaction with anaesthesia care: development of a psychometric questionnaire and benchmarking among six hospitals in Switzerland and Austria
No full textCorona Isolation Method Matters: Capillary Electrophoresis Mass Spectrometry Based Comparison of Protein Corona Compositions Following On-Particle versus In-Solution or In-Gel Digestion
No full textIncreased understanding of the role of the nanomaterial protein corona in driving nanomaterial uptake into, and impacts on, cells and organisms, and the consequent need for characterization of the corona, has led to a flourishing of methods for isolation and analysis of the constituent proteins over the past decade. However, despite over 700 corona studies to date, very little is understood in terms of which methods provide the most precise and comprehensive characterization of the corona. With the increasing importance of the modeling of corona formation and its correlation with biological impacts, it is timely to properly characterize and validate the isolation approaches used to determine the protein corona. The current work introduces Capillary Electrophoresis with Electro Spray Ionization Mass Spectrometry (CESI-MS) as a novel method for protein corona characterizations and develops an on-particle tryptic digestion method, comparing peptide solubilization solutions and characterizing the recovery of proteins from the nanomaterial surface. The CESI-MS was compared to the gold standard nano-LC-MS for corona analysis and maintained a high degree of reproducibility, while increasing throughput by >3-fold. The on-particle digestion is compared to an in-solution digestion and an in-gel digestion of the protein corona. Interestingly, a range of different protein classes were found to be recovered to greater or lesser extents among the different methods. Apolipoproteins were detected at lower concentrations when a surfactant was used to solubilize peptides, whereas immunoglobulins in general have a high affinity for nanomaterials, and thus show lower recovery using on-particle digestion. The optimized on-particle digestion was validated using 6 nanomaterials and proved capable of recovering in excess of 97% of the protein corona. These are important factors to consider when designing corona studies and modeling corona formation and impacts, highlighting the significance of a comprehensive validation of nanomaterial corona analysis methods
Patient satisfaction with anaesthesia care: development of a psychometric questionnaire and benchmarking among six hospitals in Switzerland and Austria†‡
No full textBackground. We describe the development and comparison of a psychometric questionnaire on patient satisfaction with anaesthesia care among six hospitals. Methods. We used a rigorous protocol: generation of items, construction of the pilot questionnaire, pilot study, statistical analysis (construct validity, factor analysis, reliability analysis), compilation of the final questionnaire, main study, repeated analysis of construct validity and reliability. We compared the mean total problem score and the scores for the dimensions: ‘Information/Involvement in decision‐making', and ‘Continuity of personal care by anaesthetist'. The influence of potential confounding variables was tested (multiple linear regression). Results. The average problem score from all hospitals was 18.6%. Most problems are mentioned in the dimensions ‘Information/Involvement in decision‐making' (mean problem score: 30.9%) and ‘Continuity of personal care by anaesthetist' (mean problem score: 32.2%). The overall assessment of the quality of anaesthesia care was good to excellent in 98.7% of cases. The most important dimension was ‘Information/Involvement in decision‐making'. The mean total problem score was significantly lower for two hospitals than the total mean for all hospitals (significantly higher at two hospitals) (P<0.05). Amongst the confounding variables considered, age, sex, subjective state of health, type of anaesthesia and level of education had an influence on the total problem score and the two dimensions mentioned. There were only marginal differences with and without the influence of the confounding variables for the different hospitals. Conclusions. A psychometric questionnaire on patient satisfaction with anaesthesia care must cover areas such as patient information, involvement in decision‐making, and contact with the anaesthetist. The assessment using summed scores for dimensions is more informative than a global summed rating. There were significant differences between hospitals. Moreover, the high problem scores indicate a great potential for improvement at all hospitals. Br J Anaesth 2002; 89: 863-7
On the Elasticity of Stiff Polymer Networks
No full textDiese Arbeit besch\"aftigt sich mit der Bestimmung elastischer Konstanten in amorphen Materialien. Im Mittelpunkt steht die Elastizit\"at heterogener Netzwerke aus steifen, stabartigen Polymeren. Diese Netzwerke spielen eine wichtige Rolle in der Zell-Biologie, z.B. in der Form des Zytoskeletts, welchem die Zelle einen Gro\ss teil ihrer mechanischen und dynamischen Eigenschaften
verdankt.
Bei der Bestimmung der elastischen Konstanten im Rahmen der
Elastizit\"atstheorie erh\"alt der Begriff der `Affinit\"at'' eine besondere Bedeutung, da er das Deformationsfeld \emph{homogener} elastischer Systeme
charakterisiert. Im Gegensatz dazu ist es in den hier interessierenden \emph{heterogenen} Materialsystemen gerade die Abwesenheit dieser affinen Deformationen, die im Mittelpunkt des Interesses steht. Im Verlauf der Arbeit
wird deutlich, wie Nichtaffinit\"at aus einem Zusammenspiel geometrischer Eigenschaften der Mikrostruktur und mechanischer Eigenschaften der Einzelpolymere entstehen kann. Durch die Kombination von Computersimulation und
analytischer Beschreibung werden wichtige Aspekte bez\"uglich der Rolle der heterogenen Mikrostruktur in der Ausbildung makroskopischer Elastizit\"at gekl\"art. Der Ber\"ucksichtigung nicht-affiner Deformationen kommt dabei
au{\ss}erordentliche Bedeutung bei der pr\"azisen Bestimmung makroskopischer elastischer Konstanten zu.
Es zeigt sich, dass die Struktur der Polymer-Netzwerke im Allgemeinen durch zwei L\"angenskalen beschrieben werden muss. Neben der mittleren Maschenweite tritt eine mesoskopische L\"angenskala auf, die aus der stabartigen Form der Polymere folgt. Es wird gezeigt, dass diese ``Faserl\"ange'' -- und nicht die Maschenweite -- die Rolle der Einheitszelle des Polymernetzwerkes spielt. Neben dieser geometrischen Komponente spielen die elastischen
Eigenschaften der Einzelpolymere eine wesentliche Rolle f\"ur die makroskopische Elastizit\"at. Diese orientieren sich an den bekannten Kraft-Ausdehnungs-Relationen steifer Polymere und k\"onnen mit Hilfe des ``worm-like chain'' Modells berechnet werden. Dar\"uber hinaus wird ein neues
``worm-like bundle'' Modell entwickelt, das vergleichbare Aussagen zu statistischen und mechanischen Eigenschaften von Polymer-\emph{B\"undeln} erlaubt.
Der erste Teil der Arbeit besch\"aftigt sich mit der athermischen Elastizit\"at des Netzwerkes, d.h. der entropische Anteil der Kraft-Ausdehnungs-Relation wird
vernachl\"assigt. Eine selbst-konsistente `effective-medium'' Theorie wird entwickelt, die auf der Annahme beruht, dass die Filamente sich wie \emph{inextensible}, biegesteife St\"abe verhalten. Die Annahme der Inextensibilit\"at kann mit der anisotropen Elastizit\"at steifer Polymere begr\"undet werden, deren Biegesteifigkeit, \kperp, im Allgemeinen sehr viel
kleiner ist, als deren Strecksteifigkeit, \kpar \gg \kperp. Das sich ergebende nicht-affine Deformationsfeld kann explizit konstruiert werden (``non-affine
floppy modes'') und erlaubt eine Berechnung der elastischen Konstanten der Netzwerke, welche mit den Ergebnissen fr\"uherer Simulationen \"ubereinstimmen.
Desweiteren erlaubt die Theorie, in Verbindung mit dem worm-like bundle Modell, eine Erkl\"arung der rheologischen Eigenschaften eines in-vitro Modellsystems aus
verkn\"upften Polymerb\"undeln.
Der zweite Teil der Arbeit diskutiert thermische Effekte, indem die entropische Strecksteifigkeit der Polymere in der Modellierung ber\"ucksichtigt wird. Es besteht ein charakteristischer Unterschied zwischen diesem entropischen Beitrag zur Strecksteifigkeit, \kpar, und einem energetischen Beitrag, , der sich z.B. aus der Streckung des Polymer-R\"uckgrats ergibt. Dieser Unterschied
betrifft die Abh\"angigkeit von der L\"ange des betrachteten Polymersegments. Die starke Abh\"angigkeit \kpar\sim l^{-4} (im Vergleich zu ) f\"uhrt dazu, dass thermische Netzwerke steifer Polymere eine starke Sensitivit\"at f\"ur strukturelle Unordnung aufweisen, die in athermischen Netzwerken nicht vorhanden ist. Im numerischen Modellsystem \"au{\ss}ert sich dieser Effekt durch die Existenz einer Nichtaffinit\"ats-L\"ange und dazugeh\"origer anomaler Exponenten der elastischen Konstanten. Ein Skalenargument wird entwickelt, das den Zusammenhang aufzeigt zwischen Heterogenit\"at des Netzwerks (hier charakterisiert durch die Verteilung ) und elastischer Eigenschaften des Einzelpolymers (\kpar(l))
Vitamin D in endometriosis: A causative or confounding factor?
No full textObjective The aim of this paper is to review the evidence from studies that evaluated the relationship between vitamin D and endometriosis. Design Comprehensive review. Materials and Methods Systematic literature search in Medline for relevant publications from 1946 until June 2013. Results Endometriosis risk may be influenced by dietary vitamin D intake and plasma hydroxyvitamin D concentration. Vitamin D receptor and vitamin D metabolizing enzymes, 24-hydroxylase and 1-α hydroxylase, are found in the normal cycling endometrium and also in the eutopic and ectopic endometrium of women with endometriosis. The endometrium is a target of 1, 25 dihydroxyvitamin D actions through regulation of specific genes and via immunomodulation. The endometrium in endometriosis expresses dysregulation of some vitamin D enzymes and receptors. If vitamin D and its metabolites are implicated in endometriosis-associated infertility, it is likely through interference with HOXA10 gene expression. The Gc2 phenotype of vitamin D binding protein is prevalent in women with endometriosis and may be implicated in its pathogenesis. In a mouse model, Elocalcitol, a VDR-agonist was shown to reduce the development of endometriotic lesions and recurrence. Conclusion A biological plausibility for a role of vitamin D, as an immunomodulator and anti-inflammatory agent, in the pathogenesis and treatment of endometriosis is suggested in this article, but is difficult to illustrate due to sparse evidence from human studies limited primarily to case-control studies. A significant knowledge gap precludes the establishment of a clear cause-effect relationship. 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Protein kinase N1 deficiency results in upregulation of cerebral energy metabolism and is highly protective in in vivo and in vitro stroke models.
No full textBACKGROUND AND AIM: We recently identified protein kinase N1 (PKN1) as a master regulator of brain development. However, its function in the adult brain has not been clearly established. In this study, we assessed the cerebral energetic phenotype of wildtype (WT) and global Pkn1 knockout (Pkn1-/-) animals under physiological and pathophysiological conditions. METHODS: Cerebral energy metabolism was analyzed by 13C6-glucose tracing in vivo and real time seahorse analysis of extracellular acidification rates as well as mitochondrial oxygen consumption rates (OCR) of brain slice punches in vitro. Isolated WT and Pkn1-/- brain mitochondria were tested for differences in OCR with different substrates. Metabolite levels were determined by mass spectrometric analysis in brain slices under control and energetic stress conditions, induced by oxygen-glucose deprivation and reperfusion, an in vitro model of ischemic stroke. Differences in enzyme activities were assessed by enzymatic assays, western blotting and bulk RNA sequencing. A middle cerebral artery occlusion stroke model was used to analyze lesion volumes and functional recovery in WT and Pkn1-/- mice. RESULTS: Pkn1 deficiency resulted in a remarkable upregulation of cerebral energy metabolism, in vivo and in vitro. This was due to two separate mechanisms involving an enhanced glycolytic flux and higher pyruvate-induced mitochondrial OCR. Mechanistically we show that Pkn1-/- brain tissue exhibits an increased activity of the glycolysis rate-limiting enzyme phosphofructokinase. Additionally, glucose-1,6-bisphosphate levels, a metabolite that increases mitochondrial pyruvate uptake, were elevated upon Pkn1 deficiency. Consequently, Pkn1-/- brain slices had more ATP and a greater accumulation of ATP degradation metabolites during energetic stress. This translated into increased phosphorylation and activity of adenosine monophosphate (AMP)-activated protein kinase (AMPK) during in vitro stroke. Accordingly, Pkn1-/- brain slices showed a post-ischemic transcriptional upregulation of energy metabolism pathways and Pkn1 deficiency was strongly protective in in vitro and in vivo stroke models. While inhibition of mitochondrial pyruvate uptake only moderately affected the protective phenotype, inhibition of AMPK in Pkn1-/- slices increased post-ischemic cell death in vitro. CONCLUSION: This is the first study to comprehensively demonstrate an essential and unique role of PKN1 in cerebral energy metabolism, regulating glycolysis and mitochondrial pyruvate-induced respiration. We further uncovered a highly protective phenotype of Pkn1 deficiency in both, in vitro and in vivo stroke models, validating inhibition of PKN1 as a promising new therapeutic target for the development of novel stroke therapies
Fecal detection of calprotectin subunits links inflammatory bowel disease activity with chronicity of intestinal inflammation
No full textBACKGROUND & AIMS: Quantification of the human S100A8/ S100A9 tetrameric protein complex in stool, referred to as fecal calprotectin, is an extensively validated biomarker supporting the diagnosis and management of gastrointestinal diseases. Here, we studied the quaternary protein structures (termed configuration) of S100A8 and S100A9 and their biological function in inflammatory bowel diseases (IBD). METHODS: We dissected fecal S100A8 and S100A9 configurations in patients with IBD by size-exclusion chromatography coupled with tandem mass spectrometry and systematically defined human S100A8 and S100A9 homodimer functions compared with the calprotectin heterotetramer (CP) in the intestine of mice and in human epithelium and T cells. Moreover, we report a protein interaction network of fecal S100A8 and S100A9 in IBD. RESULTS: Stool from patients with active IBD contained abundant S100A8 and S100A9 dimers besides CP. Fecal S100A9 detection associated with clinical and endoscopic disease activity in IBD patients with low CP concentration. Oral exposure to human recombinant S100A8 and S100A9 homodimers, but not to CP, worsened intestinal inflammation in toxic and genetic mouse models. Functional profiling revealed that human S100A8 and S100A9 homodimers enhanced activation of cluster of differentiation 4(+) and 8(+) T cells, which promoted experimental colitis. In turn, genetic inactivation of S100a9 protected against experimental enteritis and colitis, and pharmacologic inhibition of S100A9 ameliorated chronic colitis. CONCLUSIONS: Collectively, this study links the detection of fecal S100A9 dimers with clinical and endoscopic disease activity in IBD and identifies inflammatory actions of S100A8 and S100A9 homodimers in the intestine. Our findings pave the way for novel diagnostic and therapeutic approaches in patients with inflammatory diseases of the intestine
