keyword
MENU ▼
Read by QxMD icon Read
search

Dimitrios Stamou

keyword
https://www.readbyqxmd.com/read/27013734/direct-observation-of-proton-pumping-by-a-eukaryotic-p-type-atpase
#1
Salome Veshaguri, Sune M Christensen, Gerdi C Kemmer, Garima Ghale, Mads P Møller, Christina Lohr, Andreas L Christensen, Bo H Justesen, Ida L Jørgensen, Jürgen Schiller, Nikos S Hatzakis, Michael Grabe, Thomas Günther Pomorski, Dimitrios Stamou
In eukaryotes, P-type adenosine triphosphatases (ATPases) generate the plasma membrane potential and drive secondary transport systems; however, despite their importance, their regulation remains poorly understood. We monitored at the single-molecule level the activity of the prototypic proton-pumping P-type ATPase Arabidopsis thaliana isoform 2 (AHA2). Our measurements, combined with a physical nonequilibrium model of vesicle acidification, revealed that pumping is stochastically interrupted by long-lived (~100 seconds) inactive or leaky states...
March 25, 2016: Science
https://www.readbyqxmd.com/read/27013033/monitoring-the-waiting-time-sequence-of-single-ras-gtpase-activation-events-using-liposome-functionalized-zero-mode-waveguides
#2
Sune M Christensen, Meredith G Triplet, Christopher Rhodes, Jeffrey S Iwig, Hsiung-Lin Tu, Dimitrios Stamou, Jay T Groves
Activation of small GTPases of the Ras superfamily by guanine nucleotide exchange factors (GEFs) is a key step in numerous cell signaling processes. Unveiling the detailed molecular mechanisms of GEF-GTPase signaling interactions is of great importance due to their central roles in cell biology, including critical disease states, and their potential as therapeutic targets. Here we present an assay to monitor individual Ras activation events catalyzed by single molecules of the GEF Son of Sevenless (SOS) in the natural membrane environment...
April 13, 2016: Nano Letters
https://www.readbyqxmd.com/read/26618221/single-enzyme-experiments-reveal-a-long-lifetime-proton-leak-state-in-a-heme-copper-oxidase
#3
Mengqiu Li, Sune K Jørgensen, Duncan G G McMillan, Łukasz Krzemiński, Nikolaos N Daskalakis, Riitta H Partanen, Marijonas Tutkus, Roman Tuma, Dimitrios Stamou, Nikos S Hatzakis, Lars J C Jeuken
Heme-copper oxidases (HCOs) are key enzymes in prokaryotes and eukaryotes for energy production during aerobic respiration. They catalyze the reduction of the terminal electron acceptor, oxygen, and utilize the Gibbs free energy to transport protons across a membrane to generate a proton (ΔpH) and electrochemical gradient termed proton motive force (PMF), which provides the driving force for the adenosine triphosphate (ATP) synthesis. Excessive PMF is known to limit the turnover of HCOs, but the molecular mechanism of this regulatory feedback remains relatively unexplored...
December 30, 2015: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/26485070/membrane-curvature-bends-the-laws-of-physics-and-chemistry
#4
Lars Iversen, Signe Mathiasen, Jannik Bruun Larsen, Dimitrios Stamou
No abstract text is available yet for this article.
November 2015: Nature Chemical Biology
https://www.readbyqxmd.com/read/26382910/treating-peritoneal-mesothelioma-with-cytoreductive-surgery-and-hyperthermic-intraperitoneal-chemotherapy-a-case-series-and-review-of-the-literature
#5
Konstantinos Stamou, Dimitrios Tsamis, Nikolaos Pallas, Evangelia Samanta, Nikolaos Courcoutsakis, Panos Prassopoulos, Antonios-Apostolos Tentes
BACKGROUND: Encouraging results on survival of patients with malignant peritoneal mesothelioma have been shown with the use of cytoreductive surgery and perioperative intraperitoneal chemotherapy. This study explores the impact of aggressive surgical treatment on overall survival of peritoneal mesothelioma. METHODS: This is a retrospective analysis of prospectively collected clinical data of all patients with diagnosis of malignant peritoneal mesothelioma treated in a designated referral centre in Greece...
2015: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/25898166/calm-regulates-clathrin-coated-vesicle-size-and-maturation-by-directly-sensing-and-driving-membrane-curvature
#6
Sharon E Miller, Signe Mathiasen, Nicholas A Bright, Fabienne Pierre, Bernard T Kelly, Nikolay Kladt, Astrid Schauss, Christien J Merrifield, Dimitrios Stamou, Stefan Höning, David J Owen
The size of endocytic clathrin-coated vesicles (CCVs) is remarkably uniform, suggesting that it is optimized to achieve the appropriate levels of cargo and lipid internalization. The three most abundant proteins in mammalian endocytic CCVs are clathrin and the two cargo-selecting, clathrin adaptors, CALM and AP2. Here we demonstrate that depletion of CALM causes a substantial increase in the ratio of "open" clathrin-coated pits (CCPs) to "necked"/"closed" CCVs and a doubling of CCP/CCV diameter, whereas AP2 depletion has opposite effects...
April 20, 2015: Developmental Cell
https://www.readbyqxmd.com/read/25824101/interferometric-detection-of-single-gold-nanoparticles-calibrated-against-tem-size-distributions
#7
COMPARATIVE STUDY
Lixue Zhang, Sune M Christensen, Poul Martin Bendix, Vikram Kjøller Bhatia, Steffen Loft, Dimitrios Stamou
Single nanoparticle analysis: An interferometric optical approach calibrates sizes of gold nanoparticles (AuNPs) from the interference intensities by calibrating their interferometric signals against the corresponding transmission electron microscopy measurements. This method is used to investigate whether size affects the diffusion behavior of AuNPs conjugated to supported lipid bilayer membranes and to multiplex the simultaneous detection of three different AuNP labels.
August 5, 2015: Small
https://www.readbyqxmd.com/read/25622090/membrane-curvature-enables-n-ras-lipid-anchor-sorting-to-liquid-ordered-membrane-phases
#8
Jannik Bruun Larsen, Martin Borch Jensen, Vikram K Bhatia, Søren L Pedersen, Thomas Bjørnholm, Lars Iversen, Mark Uline, Igal Szleifer, Knud J Jensen, Nikos S Hatzakis, Dimitrios Stamou
Trafficking and sorting of membrane-anchored Ras GTPases are regulated by partitioning between distinct membrane domains. Here, in vitro experiments and microscopic molecular theory reveal membrane curvature as a new modulator of N-Ras lipid anchor and palmitoyl chain partitioning. Membrane curvature was essential for enrichment in raft-like liquid-ordered phases; enrichment was driven by relief of lateral pressure upon anchor insertion and most likely affects the localization of lipidated proteins in general...
March 2015: Nature Chemical Biology
https://www.readbyqxmd.com/read/25086504/nanoscale-high-content-analysis-using-compositional-heterogeneities-of-single-proteoliposomes
#9
Signe Mathiasen, Sune M Christensen, Juan José Fung, Søren G F Rasmussen, Jonathan F Fay, Sune K Jorgensen, Salome Veshaguri, David L Farrens, Maria Kiskowski, Brian Kobilka, Dimitrios Stamou
Proteoliposome reconstitution is a standard method to stabilize purified transmembrane proteins in membranes for structural and functional assays. Here we quantified intrareconstitution heterogeneities in single proteoliposomes using fluorescence microscopy. Our results suggest that compositional heterogeneities can severely skew ensemble-average proteoliposome measurements but also enable ultraminiaturized high-content screens. We took advantage of this screening capability to map the oligomerization energy of the β2-adrenergic receptor using ∼10(9)-fold less protein than conventional assays...
September 2014: Nature Methods
https://www.readbyqxmd.com/read/24994643/molecular-kinetics-ras-activation-by-sos-allosteric-regulation-by-altered-fluctuation-dynamics
#10
Lars Iversen, Hsiung-Lin Tu, Wan-Chen Lin, Sune M Christensen, Steven M Abel, Jeff Iwig, Hung-Jen Wu, Jodi Gureasko, Christopher Rhodes, Rebecca S Petit, Scott D Hansen, Peter Thill, Cheng-Han Yu, Dimitrios Stamou, Arup K Chakraborty, John Kuriyan, Jay T Groves
Activation of the small guanosine triphosphatase H-Ras by the exchange factor Son of Sevenless (SOS) is an important hub for signal transduction. Multiple layers of regulation, through protein and membrane interactions, govern activity of SOS. We characterized the specific activity of individual SOS molecules catalyzing nucleotide exchange in H-Ras. Single-molecule kinetic traces revealed that SOS samples a broad distribution of turnover rates through stochastic fluctuations between distinct, long-lived (more than 100 seconds), functional states...
July 4, 2014: Science
https://www.readbyqxmd.com/read/24668640/tc-99m-depreotide-spect-ct-for-lymph-node-staging-of-non-small-cell-lung-cancer
#11
Dimitris J Apostolopoulos, Efstratios N Koletsis, Trifon Spyridonidis, Anna Paschali, Nikolaos Papandrianos, Eleni Stamou, Pavlos J Vassilakos, Dimitrios Dougenis
OBJECTIVE: To investigate the potential role of Tc-99m depreotide (Tc-DEPR) in the preoperative lymph node (N) staging of non-small-cell lung cancer (NSCLC). METHODS: Sixty-one patients with NSCLC at the potentially operable stage were enrolled and underwent scintigraphy before surgery (n=56) or mediastinoscopy (n=5). Imaging was performed with a hybrid single photon emission computed tomography/computed tomography (SPECT/CT) system. Depreotide uptake in N stations was evaluated visually and semi-quantitatively and compared to histology...
June 2014: Annals of Nuclear Medicine
https://www.readbyqxmd.com/read/24411252/geometrical-membrane-curvature-as-an-allosteric-regulator-of-membrane-protein-structure-and-function
#12
Asger Tonnesen, Sune M Christensen, Vadym Tkach, Dimitrios Stamou
Transmembrane proteins are embedded in cellular membranes of varied lipid composition and geometrical curvature. Here, we studied for the first time the allosteric effect of geometrical membrane curvature on transmembrane protein structure and function. We used single-channel optical analysis of the prototypic transmembrane β-barrel α-hemolysin (α-HL) reconstituted on immobilized single small unilamellar liposomes of different diameter and therefore curvature. Our data demonstrate that physiologically abundant geometrical membrane curvatures can enforce a dramatic allosteric regulation (1000-fold inhibition) of α-HL permeability...
January 7, 2014: Biophysical Journal
https://www.readbyqxmd.com/read/24359083/single-molecule-activity-measurements-of-cytochrome-p450-oxidoreductase-reveal-the-existence-of-two-discrete-functional-states
#13
Tomas Laursen, Aparajita Singha, Nicolai Rantzau, Marijonas Tutkus, Jonas Borch, Per Hedegård, Dimitrios Stamou, Birger Lindberg Møller, Nikos S Hatzakis
Electron transfer between membrane spanning oxidoreductase enzymes controls vital metabolic processes. Here we studied for the first time with single molecule resolution the function of P450 oxidoreductase (POR), the canonical membrane spanning activator of all microsomal cytochrome P450 enzymes. Measurements and statistical analysis of individual catalytic turnover cycles shows POR to sample at least two major functional states. This phenotype may underlie regulatory interactions with different cytochromes P450 but to date has remained masked in bulk kinetics...
March 21, 2014: ACS Chemical Biology
https://www.readbyqxmd.com/read/24055060/membrane-sculpting-bar-domains-generate-stable-lipid-microdomains
#14
Hongxia Zhao, Alphée Michelot, Essi V Koskela, Vadym Tkach, Dimitrios Stamou, David G Drubin, Pekka Lappalainen
Bin-Amphiphysin-Rvs (BAR) domain proteins are central regulators of many cellular processes involving membrane dynamics. BAR domains sculpt phosphoinositide-rich membranes to generate membrane protrusions or invaginations. Here, we report that, in addition to regulating membrane geometry, BAR domains can generate extremely stable lipid microdomains by "freezing" phosphoinositide dynamics. This is a general feature of BAR domains, because the yeast endocytic BAR and Fes/CIP4 homology BAR (F-BAR) domains, the inverse BAR domain of Pinkbar, and the eisosomal BAR protein Lsp1 induced phosphoinositide clustering and halted lipid diffusion, despite differences in mechanisms of membrane interactions...
September 26, 2013: Cell Reports
https://www.readbyqxmd.com/read/23856986/single-vesicle-biochips-for-ultra-miniaturized-nanoscale-fluidics-and-single-molecule-bioscience
#15
REVIEW
Andreas L Christensen, Christina Lohr, Sune M Christensen, Dimitrios Stamou
One of the major bottlenecks in the development of biochips is maintaining the structure and function of biomolecules when interfacing them with hard matter (glass, plastics, metals, etc.), a challenge that is exacerbated during miniaturization that inevitably increases the interface to volume ratio of these devices. Biochips based on immobilized vesicles circumvent this problem by encapsulating biomolecules in the protective environment of a lipid bilayer, thus minimizing interactions with hard surfaces. Here we review the development of biochips based on arrays of single nanoscale vesicles, their fabrication via controlled self-assembly, and their characterization using fluorescence microscopy...
September 21, 2013: Lab on a Chip
https://www.readbyqxmd.com/read/23836127/the-effect-of-laparoscopic-sleeve-gastrectomy-on-the-antireflux-mechanism-can-it-be-minimized
#16
Eleftheria Kleidi, Dimitrios Theodorou, Konstantinos Albanopoulos, Evangelos Menenakos, Michail A Karvelis, Joanna Papailiou, Konstantinos Stamou, Georgios Zografos, Stylianos Katsaragakis, Emmanuel Leandros
BACKGROUND: Laparoscopic sleeve gastrectomy (LSG) is a promising procedure for the treatment of morbid obesity. The stomach is usually transected near the angle of His; hence, the lower esophageal sphincter (LES) may be affected with consequences on postoperative gastroesophageal reflux disease (GERD). The purpose of this study was to examine the effect of LSG on the LES and postoperative GERD. METHODS: Severely obese asymptomatic patients submitted to LSG underwent esophageal manometry and GERD evaluation preoperatively and at least 6 weeks postoperatively...
December 2013: Surgical Endoscopy
https://www.readbyqxmd.com/read/23630454/pick1-deficiency-impairs-secretory-vesicle-biogenesis-and-leads-to-growth-retardation-and-decreased-glucose-tolerance
#17
Birgitte Holst, Kenneth L Madsen, Anna M Jansen, Chunyu Jin, Mattias Rickhag, Viktor K Lund, Morten Jensen, Vikram Bhatia, Gunnar Sørensen, Andreas N Madsen, Zhichao Xue, Siri K Møller, David Woldbye, Klaus Qvortrup, Richard Huganir, Dimitrios Stamou, Ole Kjærulff, Ulrik Gether
Secretory vesicles in endocrine cells store hormones such as growth hormone (GH) and insulin before their release into the bloodstream. The molecular mechanisms governing budding of immature secretory vesicles from the trans-Golgi network (TGN) and their subsequent maturation remain unclear. Here, we identify the lipid binding BAR (Bin/amphiphysin/Rvs) domain protein PICK1 (protein interacting with C kinase 1) as a key component early in the biogenesis of secretory vesicles in GH-producing cells. Both PICK1-deficient Drosophila and mice displayed somatic growth retardation...
2013: PLoS Biology
https://www.readbyqxmd.com/read/23535634/fbar-syndapin-1-recognizes-and-stabilizes-highly-curved-tubular-membranes-in-a-concentration-dependent-manner
#18
Pradeep Ramesh, Younes F Baroji, S Nader S Reihani, Dimitrios Stamou, Lene B Oddershede, Poul Martin Bendix
Syndapin 1 FBAR, a member of the Bin-amphiphysin-Rvs (BAR) domain protein family, is known to induce membrane curvature and is an essential component in biological processes like endocytosis and formation and growth of neurites. We quantify the curvature sensing of FBAR on reconstituted porcine brain lipid vesicles and show that it senses membrane curvature at low density whereas it induces and reinforces tube stiffness at higher density. FBAR strongly up-concentrates on the high curvature tubes pulled out of Giant Unilamellar lipid Vesicles (GUVs), this sorting behavior is strongly amplified at low protein densities...
2013: Scientific Reports
https://www.readbyqxmd.com/read/23085988/molecular-basis-for-snx-bar-mediated-assembly-of-distinct-endosomal-sorting-tubules
#19
Jan R T van Weering, Richard B Sessions, Colin J Traer, Daniel P Kloer, Vikram K Bhatia, Dimitrios Stamou, Sven R Carlsson, James H Hurley, Peter J Cullen
Sorting nexins (SNXs) are regulators of endosomal sorting. For the SNX-BAR subgroup, a Bin/Amphiphysin/Rvs (BAR) domain is vital for formation/stabilization of tubular subdomains that mediate cargo recycling. Here, by analysing the in vitro membrane remodelling properties of all 12 human SNX-BARs, we report that some, but not all, can elicit the formation of tubules with diameters that resemble sorting tubules observed in cells. We reveal that SNX-BARs display a restricted pattern of BAR domain-mediated dimerization, and by resolving a 2...
November 28, 2012: EMBO Journal
https://www.readbyqxmd.com/read/23052507/c-reactive-protein-white-blood-cells-and-neutrophils-as-early-predictors-of-postoperative-complications-in-patients-undergoing-laparoscopic-sleeve-gastrectomy
#20
Konstantinos Albanopoulos, Leonidas Alevizos, Maria Natoudi, Dimitrios Dardamanis, Evangelos Menenakos, Konstantinos Stamou, George Zografos, Emmanuel Leandros
BACKGROUND: Early detection and treatment of complications after laparoscopic sleeve gastrectomy (LSG) are mandatory. This study aimed to evaluate C-reactive protein (CRP), white blood cell (WBC) count, and neutrophil (NEU) count in relation to the early diagnosis of major surgical complications after LSG. METHODS: A prospective study of 177 patients who underwent LSG during 2008-2011 was performed. Measurements of WBC, NEU, and CRP performed on postoperative days 0, 1, 3, 5, 7, 9, 11, 13, and 30 were correlated with postoperative surgical complications...
March 2013: Surgical Endoscopy
keyword
keyword
81893
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"