DOCSLIB.ORG

ON STATISTICAL MODELS and PRIOR DISTRIBUTIONS in the THEORY of CHEMICAL REACTIONS A. BEN-SHAUL Main Characteristics: (I) the E

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
ON STATISTICAL MODELS and PRIOR DISTRIBUTIONS in the THEORY of CHEMICAL REACTIONS A. BEN-SHAUL Main Characteristics: (I) the E Chemical Physics 22 (1977) 341-366 0 NorthHolland PubIishing Company ON STATISTICAL MODELS AND PRIOR DISTRIBUTIONS IN THE THEORY OF CHEMICAL REACTIONS A. BEN-SHAUL Department of Physical Chemistry, The Hebrew University,Jerusalem, Israel Received 3 January 1977 _ Statistical models which yield rate expressions involving the asymptotic channel states are classifiedaccording to thiee main characteristics:(i) The ensemblein which frameworkthe basic statisticalassumption is formulated.This assumption states that the initial and final states of the collision are, partly or completely, independent. (ii) The “measure in phase” associated with the product state distriiution. (iii) The extent to which dynamicat considerations are incorporated into the &deI. In this connection the discussion wih be confmed to the effects of angular momentum restrictions. The diversity in statistical models is demonstrated by comparing the product vibrational and rotational distributions obtained from several models for atom-diatom exchange reactions. Numerical results are presented for two cxoergic reactions which involve dif- ferent mass combinations. Particular attention is paid to a comparison between the objectives, assumptions and the final expressions for product state distributions corresponding to the so called phase space theory on the one hand and the prior (zero surprisal) limit of the information theoretic approach to moIecular dynamics on the other. I. Introduction inversion. In such cases one may use the statistical models as standards against which actual results can Many theories of molecular [l-4] and nuclear [.5, be compared [ 181 or as bases for the development 61 collisions employ (various) statistical assumptions of more elaborate models. In the information theoretic to describe collision processes and to predict their approach to molecular collision dynamics [42--721 outcomes. In molecular physics the main success of such standards can serve as the prior distributions these theories is in the area of large molecules where (rate constants, cross sections) used in surprisal and many degrees of freedom are involved so that .detailed entropy analyses of experimental data. When supple- dynamical calculations are impractical while statistical mented by appropriate dynamical constraints the approximations seem reasonable (see, however, e.g. prior distributions play a major role in the predictive refs; [7,8]). Since detailed calculations are difficult scheme (synthesis) based on the maximum entropy to pitfo~rm, partly due to .#te lack of accumte potential principle. energy surfaces, even for small systems, such as atom- The central assumption of the statistical models is diatomic molecule, various statistical models were that past and future with respect to the collision formulated in order to account for at least some as- event are partly or completely independent; subject to pects of the coilision [g-41]. For example, the sym- symmetry and conservation requirements. The sym- metric product angular distributions observed in certain metry requirements refer in particular to microscopic bimolecular reactions can be interpreted as the result reversibility while the conservation rules concern the of intermediate complex formation followed by total (center of mass) energy E, total angular momen- “statistical” breakdown probabilities [3,4,9-I 1,19, tum K and the normalization of probabilities. Approxi- 271. The statistical models are less successful in pre- mate dynamical information, e.g. on the range of dicting, for instance, the product vibrational and allowed anguIar momenta, is usually incorporated rotational energy distributions in exoergic chemical into the mod& in order to increase their dynamical reactions; especially in those ending with population character. The concepts of intermediate, “long lived” 342 A. Be;r.Sl:aul/Ti:eorJ’ of chemical reactions (see, e.g. refs. [I-4, 7-1 I ] ) or “strongly coupled”. discussion. Yet, even within the limited scope of [ 14-191, collision complexes play important r’ resin “asymptotic channel statistical approaches” there is various statistical theories. They serve to account for room for diverse, actually an infinity of, different “quasi-equilibrium” (‘energy randomization”) [l-d, models. 7,18,33,34] or “strong coupling” [4,11,14-191 The general purpose of this paper’is to characterize postulates on the basis of which the neglect of corre- the various aspects of diversity in a systematic fashion. lation between reactants and products can be justified. Particularattention will be paid to a comparisonbe- In the traditional formulations of transition state theory tween two familiar rate expressions.Namely, the cross a quasi-equilibrium is assumed to exist between the sections and related quantities obtained in the phase reactants and the systems crossing the activated com- space theory of Light, Pechukas and Nikitin [ 14-281 pies hypersurface (see e.g. refs. [4,7,37] ). Recent and the prior distributions appearing in the informa- work [36,37j (utilizing variational principles to locate tion theoretic approach developed by Levine, Bernstein the transition hypersurfacc, see e.g. refs. [12,38-411) and others [42-723. Unlike the phase space theory indicates that transition state theory is appropriate the prior distributions do not contain any dynamical to a “direct”, as opposed to “complex”. reaction information and therefore do not attempt to predict mechanism, whereas the well known [ 14-271 phase experimental results. In fact, they are meant to re- space theory of’light, Pechukas [14-191 and present the dynamically “least biased” (or “most Nikitin 129,211 (LPN) is only applicable to reactions random”) distributions [42-501. As such they can proceeding-via the formation of long lived complexes. either be used as standards for entropy-surprisal anal- This interpretation of the phase space theory is some- yses or else as starting points in the predictive scheme what different from the one suggested in some of its (synthesis) which constitutes another direction of the original formulations [14-191 where a strongly information theoretic method. Although the LPN and coupled complex defined by the region of strong in- the prior distributions involve different statistical teraction in configuration space rather than by its ensembles (E, K versus E) and different measures in lifetime was assumed to be formed. phase space (“uniform” versus “flux”), one can also To conclude this background survey it should be observe certain similarities. We shall elaborate upon mentioned that the LPN theory, to which considerable these differences and similarities within the general attention will be given in the following, can be derived classification framework of statistical models presented as a limiting case of other statistical-dynamical ap- in the following sections. Among the special models proaches. For example. it can be viewed as transition considered, we have included an extended version state theory for “loose complexes” [37,41]. Also, OFthe prior distribution which explicitly includes the and this is of greater interest in the present context, conservation of angular momentum (i.e., appropriate with the aid of a random phase type approximation to the E, K ensemble). As specific examples illustrating the phase space model can be derived through formal the consequences of different statistical assumptions, assumptions on the structure of the scattering matrix we have chosen the Cl + HI + HCI + I and the H f Cl2 [4.11,19,1-21: similar to those made in the statistical + HCl t Cl reactions. theory of rotational excitation [ 131. Two more remarks should precede the discussion. The main concern of this paper is the statistical, First, some points related to the objectives of this rather than the dynamical, aspects of statistical- paper have already been dealt with in the literature dynamical approaches to small collision systems. We [ 11,27,43,45,49-551 (to a greater or lesser extent). shall only consider models that lead to rate expressions In our opinion, however, no clear distinctions have (e.g., cross sections or product state distributions) been provided. Hence the motivation for this paper. involving the asymptotic reactant and product states, Second, for reasons to be clarified throughout the or equivalently the phase space regions corresponding paper, the presentation of the various models and the to the asymptotic channels_ Thus, many (interesting) analyses of their physical significance will not be questions regarding, for example, the behaviour and accompanied by judgements or evaluations. structure of the colliding system at intermediate. The paper is organized as follows: The basic defini- separationscare beyond the perspectives of the present tions and the general structure of statistical models A. Ben-Shul/Theory of chemical reactions 343 are presented in the next section. Different choices of more specific ensemble, I’t C I‘,, representative of statistical ensembles, measures in phase space and collisions with well defined total energy E and total dynamical constraints are considered in sections 3,4 angular momentum K. (Averaged, not summed, over and 5, respectively and tested for two specific exam- the 2K f I equivalent values of MK.)-The “canonical” ples in section 6. Section 7 provides some remarks on ensemble I’3 = T, (r2 C lY3),which is a Boltzmann the derivation based on the assumption of complex superposition of microcanonical ensembles will formation and the beginning of the derivation based
Load more

Recommended publications
  • A Thermodynamic Based Interpretation of Protein Expression Heterogeneity in Different GBM Tumors Identifies Tumor Specific Unbalanced Processes
    A Thermodynamic-Based Interpretation of Protein Expression Heterogeneity in Different Glioblastoma Multiforme Tumors Identifies Tumor-Specific Unbalanced Processes The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Kravchenko-Balasha, Nataly; Johnson, Hannah and White, Forest M. “A Thermodynamic-Based Interpretation of Protein Expression Heterogeneity in Different Glioblastoma Multiforme Tumors Identifies Tumor-Specific Unbalanced Processes.” The Journal of Physical Chemistry B 120, 26 (July 2016): 5990–5997 © 2016 American Chemical Society As Published http://dx.doi.org/10.1021/acs.jpcb.6b01692 Publisher American Chemical Society (ACS) Version Author's final manuscript Citable link http://hdl.handle.net/1721.1/110914 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. HHS Public Access Author manuscript Author ManuscriptAuthor Manuscript Author J Phys Chem Manuscript Author B. Author Manuscript Author manuscript; available in PMC 2017 July 07. Published in final edited form as: J Phys Chem B. 2016 July 7; 120(26): 5990–5997. doi:10.1021/acs.jpcb.6b01692. A Thermodynamic Based Interpretation of Protein Expression Heterogeneity in Different GBM Tumors Identifies Tumor Specific Unbalanced Processes Nataly Kravchenko-Balasha1,2, Hannah Johnson3, Forest M. White4, James R. Heath1,#, and R. D. Levine5,6,* 1NanoSystems Biology Cancer Center, Division
    [Show full text]
  • Surprisal Analysis Characterizes the Free Energy Time Course of Cancer Cells Undergoing Epithelial-To- Mesenchymal Transition
    Surprisal analysis characterizes the free energy time course of cancer cells undergoing epithelial-to- mesenchymal transition Sohila Zadrana, Rameshkumar Arumugamb, Harvey Herschmanc, Michael E. Phelpsc, and R. D. Levineb,c,d,1 aInstitute for Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095; bThe Fritz Haber Research Center, The Hebrew University, Jerusalem 91904, Israel; and cDepartment of Molecular and Medical Pharmacology, David Geffen School of Medicine, and dDepartment of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095 Contributed by R. D. Levine, August 3, 2014 (sent for review May 19, 2014) The epithelial-to-mesenchymal transition (EMT) initiates the invasive consider constraints responsible for deviations from this state. In and metastatic behavior of many epithelial cancers. Mechanisms principle, one should identify the stable state from first biophysical underlying EMT are not fully known. Surprisal analysis of mRNA time principles. However, for systems of such molecular complexity, we course data from lung and pancreatic cancer cells stimulated to must apply computational abilities beyond what is currently undergo TGF-β1–induced EMT identifies two phenotypes. Examina- available. We therefore identify the stable state by using available tion of the time course for these phenotypes reveals that EMT re- experimental data. We then have a baseline for our second task, examining deviations from the stable state. programming is a multistep process characterized by initiation, “ ” maturation, and stabilization stages that correlate with changes in We use the term state in the chemistry and physics sense, cell metabolism. Surprisal analysis characterizes the free energy time meaning everything we need to specify to predict how the system course of the expression levels throughout the transition in terms of will change in response to a small modulation of its circum- stances.
    [Show full text]
  • Information-Theoretic Analysis of Phenotype Changes in Early Stages of Carcinogenesis
    Information-theoretic analysis of phenotype changes in early stages of carcinogenesis F. Remaclea,b,1, Nataly Kravchenko-Balashac,1, Alexander Levitzkic,2, and R. D. Levineb,d,2 aFonds National de la Recherche Scientifique, Département de Chimie, Université de Liège, B4000 Liège, Belgium; bThe Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel; cUnit of Cellular Signaling, Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel; and dCrump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095 Contributed by R. D. Levine, April 20, 2010 (sent for review March 3, 2010) Cancer is a multistep process characterized by altered signal the present study by comparison with the results of bioinformatics transduction, cell growth, and metabolism. To identify such pro- and biochemical analysis (2). cesses in early carcinogenesis we use an information theoretic Our theoretical approach is based on the proposition that the approach to characterize gene expression quantified as mRNA process of gene expression and signal transduction is subject to levels in primary keratinocytes (K) and human papillomavirus 16 the same quantitative laws as inanimate nonequilibrium systems (HPV16)-transformed keratinocytes (HF1 cells) from early (E) and in physics and chemistry. For some time we have explored the late (L) passages and from benzo(a)pyrene-treated (BP) L cells. Our application of the procedure of maximal entropy to describe such starting point is that biological signaling processes are subjected systems (3).This approach, called “surprisal analysis,” was initially to the same quantitative laws as inanimate, nonequilibrium chem- introduced to characterize the selectivity of energy requirements ical systems.
    [Show full text]
  • Supplementary Methods and Figures
    Supplementary Information Decoding cancer heterogeneity: studying patient-specific signaling signatures towards personalized cancer therapy Efrat Flashner-Abramson1#, Swetha Vasudevan1#, Ibukun Adesoji Adejumobi1, Amir Sonnenblick2 and Nataly Kravchenko-Balasha1,* 1Department for Bio-medical Research, Institute of Dental Sciences, Hebrew University of Jerusalem, Jerusalem 91120, Israel 2 Oncology Division, Tel Aviv Sourasky Medical Center, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel *Corresponding author: [email protected] # Equal contribution Table of content: Supplementary Methods ................................................................................................................................................... 3 Surprisal analysis. ......................................................................................................................................................... 3 Determination of the number of significant unbalanced processes. .............................................................................. 6 Generation of functional subnetworks. ......................................................................................................................... 7 Calculation of barcodes. ................................................................................................................................................ 7 Cell lines and reagents. ................................................................................................................................................
    [Show full text]
  • A Synaptic Neural Network and Synapse Learning
    Under review as a conference paper at ICLR 2019 ASYNAPTIC NEURAL NETWORK AND SYNAPSE LEARNING Anonymous authors Paper under double-blind review ABSTRACT A Synaptic Neural Network (SynaNN) consists of synapses and neurons. Inspired by the synapse research of neuroscience, we built a synapse model with a nonlinear synapse function of excitatory and inhibitory channel probabilities. Introduced the concept of surprisal space and constructed a commutative diagram, we proved that the inhibitory probability function -log(1-exp(-x)) in surprisal space is the topologically conjugate function of the inhibitory complementary probability 1-x in probability space. Furthermore, we found that the derivative of the synapse over the parameter in the surprisal space is equal to the negative Bose-Einstein distribution. In addition, we constructed a fully connected synapse graph (tensor) as a synapse block of a synaptic neural network. Moreover, we proved the gradient formula of a cross-entropy loss function over parameters, so synapse learning can work with the gradient descent and backpropagation algorithms. In the proof-of-concept experiment, we performed an MNIST training and testing on the MLP model with synapse network as hidden layers. 1 INTRODUCTION Synapses play an important role in biological neural networks (Hubel & Kandel (1979)). They are joint points of neurons’ connection with the capability of learning and memory in neural networks. Based on the analysis of excitatory and inhibitory channels of synapses(Hubel & Kandel (1979)), we proposed a probability model (Feller (2008) for probability introduction) of the synapse together with a non-linear function of excitatory and inhibitory probabilities (Li (2017)(synapse function)).
    [Show full text]
  • Personalized Disease Signatures Through Information-Theoretic
    Personalized disease signatures through information- theoretic compaction of big cancer data Swetha Vasudevana,b, Efrat Flashner-Abramsona, F. Remacleb,c, R. D. Levineb,d,e,1, and Nataly Kravchenko-Balashaa,1 aBio-Medical Sciences Department, The Faculty of Dental Medicine, The Hebrew University of Jerusalem, 9112001 Jerusalem, Israel; bFritz Haber Research Centre, Institute of Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel; cTheoretical Physical Chemistry, Research Unit Molecular Systems, University of Liege, B4000 Liege, Belgium; dDepartment of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095; and eDepartment of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095 Contributed by R. D. Levine, June 12, 2018 (sent for review March 14, 2018; reviewed by Jeffrey C. Hoch, Yaakov Levy, and Peter Salamon) Every individual cancer develops and grows in its own specific Our main goal in this study was to develop a method that way, giving rise to a recognized need for the development of classifies patients not only based on their tumor-specific list of personalized cancer diagnostics. This suggested that the identifi- oncogenic biomarkers but also, based on the molecular context cation of patient-specific oncogene markers would be an effective that gave rise to this list of biomarkers. To this end, we in- diagnostics approach. However, tumors that are classified as vestigated gene expression alterations in a cohort of 527 samples similar according to the expression levels of certain oncogenes consisting of lymphoma, bladder cancer, gastric cancer, co- can eventually demonstrate divergent responses to treatment. lorectal cancer, breast cancer, and normal gastric tissues, and we This implies that the information gained from the identification of identified the set of ongoing molecular processes that make up tumor-specific biomarkers is still not sufficient.
    [Show full text]
  • General Rate Equation for Maximal Entropy Generation in a Maximum-Entropy Landscape with Time-Dependent Constraints
    Entropy 2008, 10, 160-182; DOI: 10.3390/entropy-e10030160 OPEN ACCESS entropy ISSN 1099-4300 Article www.mdpi.org/entropy Modeling Non-Equilibrium Dynamics of a Discrete Probability Distribution: General Rate Equation for Maximal Entropy Generation in a Maximum-Entropy Landscape with Time-Dependent Constraints Gian Paolo Beretta Universita` di Brescia, via Branze 38, Brescia, I-25123, Italy, E-mail: [email protected] Temporary address: Massachusetts Institute of Technology, Room 3-237, Cambridge, MA 01239, USA Received: 17 December 2007; in revised form: 30 July 2008 / Accepted: 30 July 2008 / Published: 14 August 2008 Abstract: A rate equation for a discrete probability distribution is discussed as a route to describe smooth relaxation towards the maximum entropy distribution compatible at all times with one or more linear constraints. The resulting dynamics follows the path of steepest en- tropy ascent compatible with the constraints. The rate equation is consistent with the Onsager theorem of reciprocity and the fluctuation-dissipation theorem. The mathematical formalism was originally developed to obtain a quantum theoretical unification of mechanics and ther- modinamics. It is presented here in a general, non-quantal formulation as a part of an effort to develop tools for the phenomenological treatment of non-equilibrium problems with appli- cations in engineering, biology, sociology, and economics. The rate equation is also extended to include the case of assigned time-dependences of the constraints and the entropy, such as for modeling non-equilibrium energy and entropy exchanges. Keywords: maximum entropy formalism, maximum entropy production, steepest en- tropy ascent, nonequilibrium dynamics, irreversible thermodynamics, Onsager reciprocity, fluctuation-dissipation relations, entropy generation by irreversibility, nonequilibrium tem- perature, constrained equilibrium, nonlinear dynamical systems Entropy 2008, 10 161 1.
    [Show full text]
  • Single Cell Proteomics in Biomedicine: High-Dimensional Data Acquisition
    www.proteomics-journal.com Page 1 Proteomics Single Cell Proteomics in Biomedicine: High-dimensional Data Acquisition, Visualization and Analysis Yapeng Su1,2, Qihui Shi3*, and Wei Wei1,4* 1NanoSystems Biology Cancer Center; 2Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA; 3Key Laboratory of Systems Biomedicine (Ministry of Education), School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China. 4Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA; *Correspondence and requests for materials should be addressed to W.W. ([email protected]) or Q.H.S. ([email protected]) Keywords: Information theoretical approaches/ Mass cytometry / Single cell barcode chip / Single cell data analysis / Single cell proteomics Abbreviations: ELISPOT, Enzyme-Linked ImmunoSpot; SiMoA, single molecule array; SCBC, single cell barcode chip; scWesterns, single cell western blot; FFC, fluorescence flow cytometry; CyTOF, cytometry by time- Received: 31/10/2016; Revised: 20/01/2017; Accepted: 20/01/2017 This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/pmic.201600267. This article is protected by copyright. All rights reserved. www.proteomics-journal.com
    [Show full text]
  • Resistance Is Futile: Physical Science, Systems Biology and Single-Cell Analysis to Understanding the Plastic and Heterogeneous
    Resistance is Futile: Physical science, systems biology and single-cell analysis to understanding the plastic and heterogeneous nature of melanoma and their role in non- genetic drug resistance Thesis by Yapeng Su In Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2020 (Defended November 22, 2019) ii 2020 Yapeng Su ORCID: 0000-0002-6305-8467 iii ACKNOWLEDGEMENTS As I come close to the end of the Ph.D. chapter in my life, I look back on this unforgettable journey and feel thankful for the help and support of so many amazing people without whom I would not have been able to complete this thesis. I would like to especially mention some individuals. First and foremost, I would like to express my deepest gratitude to my primary advisor, Prof. James Heath, for having me in the lab and guiding and supporting me to explore the most cutting-edge science throughout my graduate study. He has given me an incredible amount of intellectual freedom to pursue my own research ideas and interest while always supporting me with unlimited resources and inspiring intellectual guidance throughout my scientific adventures. He, as an example of a great scientist and visionary leader, has indelibly enriched me and shaped my identity as a researcher. I feel lucky and proud to work with Jim and I could not imagine having a better advisor and mentor for my entire Ph.D. study. I also want to extend my heartfelt thanks to my thesis co-advisor, Prof. David Baltimore, and my academic co-advisor, Prof.
    [Show full text]
  • Surprisal Analysis of Genome-Wide Transcript Profiling Identifies
    RESEARCH ARTICLE Surprisal analysis of genome-wide transcript profiling identifies differentially expressed genes and pathways associated with four growth conditions in the microalga Chlamydomonas Kenny A. Bogaert1, Sheeba S. Manoharan-Basil2, Emilie Perez2, Raphael D. Levine3,4, a1111111111 Francoise Remacle1*, Claire Remacle2* a1111111111 a1111111111 1 Theoretical Physical Chemistry, UR MOLSYS, University of Liège, Liège, Belgium, 2 Genetics and Physiology of Microalgae, UR InBios, University of Liège, Liège, Belgium, 3 The Fritz Haber Research Center a1111111111 for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem, Israel, a1111111111 4 Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America * [email protected] (CR); [email protected] (FR) OPEN ACCESS Citation: Bogaert KA, Manoharan-Basil SS, Perez Abstract E, Levine RD, Remacle F, Remacle C (2018) Surprisal analysis of genome-wide transcript The usual cultivation mode of the green microalga Chlamydomonas is liquid medium and profiling identifies differentially expressed genes light. However, the microalga can also be grown on agar plates and in darkness. Our aim is to and pathways associated with four growth analyze and compare gene expression of cells cultivated in these different conditions. For conditions in the microalga Chlamydomonas. PLoS ONE 13(4): e0195142. https://doi.org/10.1371/ that purpose, RNA-seq data are obtained from Chlamydomonas samples of two different labs journal.pone.0195142 grown in four environmental conditions (agar@light, agar@dark, liquid@light, liquid@dark). Editor: Sara Amancio, Universidade de Lisboa The RNA seq data are analyzed by surprisal analysis, which allows the simultaneous meta- Instituto Superior de Agronomia, PORTUGAL analysis of all the samples.
    [Show full text]
  • Convergence of Logic of Cellular Regulation in Different
    Kravchenko-Balasha et al. BMC Systems Biology 2011, 5:42 http://www.biomedcentral.com/1752-0509/5/42 RESEARCHARTICLE Open Access Convergence of Logic of Cellular Regulation in Different Premalignant Cells by an Information Theoretic Approach Nataly Kravchenko-Balasha1†, F Remacle2,3†, Ayelet Gross3, Varda Rotter4*, Alexander Levitzki1* and RD Levine3,5* Abstract Background: Surprisal analysis is a thermodynamic-like molecular level approach that identifies biological constraints that prevents the entropy from reaching its maximum. To examine the significance of altered gene expression levels in tumorigenesis we apply surprisal analysis to the WI-38 model through its precancerous states. The constraints identified by the analysis are transcription patterns underlying the process of transformation. Each pattern highlights the role of a group of genes that act coherently to define a transformed phenotype. Results: We identify a major transcription pattern that represents a contraction of signaling networks accompanied by induction of cellular proliferation and protein metabolism, which is essential for full transformation. In addition, a more minor, “tumor signature” transcription pattern completes the transformation process. The variation with time of the importance of each transcription pattern is determined. Midway through the transformation, at the stage when cells switch from slow to fast growth rate, the major transcription pattern undergoes a total inversion of its weight while the more minor pattern does not contribute before that stage. Conclusions: A similar network reorganization occurs in two very different cellular transformation models: WI-38 and the cervical cancer HF1 models. Our results suggest that despite differences in a list of transcripts expressed in different cancer models the rationale of the network reorganization remains essentially the same.
    [Show full text]
  • Surprisal Analysis of Glioblastoma Multiform (GBM) Microrna Dynamics Unveils Tumor Specific Phenotype
    Surprisal Analysis of Glioblastoma Multiform (GBM) MicroRNA Dynamics Unveils Tumor Specific Phenotype Sohila Zadran1, Francoise Remacle2, Raphael Levine3,4* 1 Institute of Molecular Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, 2 Department of Chemistry, B6c, University of Liege, Liege, Belgium, 3 Crump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, 4 Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem, Israel Abstract Gliomablastoma multiform (GBM) is the most fatal form of all brain cancers in humans. Currently there are limited diagnostic tools for GBM detection. Here, we applied surprisal analysis, a theory grounded in thermodynamics, to unveil how biomolecule energetics, specifically a redistribution of free energy amongst microRNAs (miRNAs), results in a system deviating from a non-cancer state to the GBM cancer –specific phenotypic state. Utilizing global miRNA microarray expression data of normal and GBM patients tumors, surprisal analysis characterizes a miRNA system response capable of distinguishing GBM samples from normal tissue biopsy samples. We indicate that the miRNAs contributing to this system behavior is a disease phenotypic state specific to GBM and is therefore a unique GBM-specific thermodynamic signature. MiRNAs implicated in the regulation of stochastic signaling processes crucial in the hallmarks of human cancer, dominate this GBM-cancer phenotypic state. With this theory, we were able to distinguish with high fidelity GBM patients solely by monitoring the dynamics of miRNAs present in patients’ biopsy samples. We anticipate that the GBM-specific thermodynamic signature will provide a critical translational tool in better characterizing cancer types and in the development of future therapeutics for GBM.
    [Show full text]