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Graph Theory

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https://www.readbyqxmd.com/read/28092321/dexmedetomidine-disrupts-the-local-and-global-efficiencies-of-large-scale-brain-networks
#1
Javeria A Hashmi, Marco L Loggia, Sheraz Khan, Lei Gao, Jieun Kim, Vitaly Napadow, Emery N Brown, Oluwaseun Akeju
BACKGROUND: A clear understanding of the neural basis of consciousness is fundamental to research in clinical and basic neuroscience disciplines and anesthesia. Recently, decreased efficiency of information integration was suggested as a core network feature of propofol-induced unconsciousness. However, it is unclear whether this finding can be generalized to dexmedetomidine, which has a different molecular target. METHODS: Dexmedetomidine was administered as a 1-μg/kg bolus over 10 min, followed by a 0...
January 16, 2017: Anesthesiology
https://www.readbyqxmd.com/read/28073939/nanoscale-molecular-reorganization-of-the-inhibitory-postsynaptic-density-is-a-determinant-of-gabaergic-synaptic-potentiation
#2
Francesca Pennacchietti, Sebastiano Vascon, Thierry Nieus, Christian Rosillo, Sabyasachi Das, Shiva Tyagarajan, Alberto Diaspro, Alessio Del Bue, Enrica Maria Petrini, Andrea Barberis, Francesca Cella Zanacchi
: Gephyrin is a key scaffold protein mediating the anchoring of GABAA receptors at inhibitory synapses. Here we exploited super-resolution techniques combined with proximity-based clustering analysis and model simulations to investigate the single molecule gephyrin reorganization during plasticity of inhibitory synapses in mouse hippocampal cultured neurons. This approach revealed that during the expression of inhibitory long-term potentiation the increase of gephyrin density at postsynaptic sites is associated with the promoted formation of gephyrin nano-domains...
January 10, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28072380/network-functional-connectivity-and-whole-brain-functional-connectomics-to-investigate-cognitive-decline-in-neurodegenerative-conditions
#3
REVIEW
O Dipasquale, Mara Cercignani
Non-invasive mapping of brain functional connectivity (FC) has played a fundamental role in neuroscience, and numerous scientists have been fascinated by its ability to reveal the brain's intricate morphology and functional properties. In recent years, two different techniques have been developed that are able to explore FC in pathophysiological conditions and to provide simple and non-invasive biomarkers for the detection of disease onset, severity and progression. These techniques are independent component analysis, which allows a network-based functional exploration of the brain, and graph theory, which provides a quantitative characterization of the whole-brain FC...
October 2016: Functional Neurology
https://www.readbyqxmd.com/read/28071906/single-conformation-spectroscopy-of-suberoylanilide-hydroxamic-acid-saha-a-molecule-bites-its-tail
#4
Di Zhang, Karl N Blodgett, Xiao Zhu, Timothy S Zwier
Suberoylanilide hydroxamic acid (C6H5NHCO(CH2)6CONHOH, SAHA) is a histone deacetylase inhibitor that causes growth arrest and differentiation of many tumor types and is an approved drug for the treatment of cancer. With a hydrogen-bonding amide group adjacent to its phenyl ring "head", and a hydroxamic acid group at the "tail" end of a C6 alkyl chain linker, SAHA possesses an interesting potential energy landscape to be probed by single-conformation methods. The alkyl chain's preference for extended structures is in competition with tail-to-head (T-H) or head-to-tail (H-T) hydrogen bonds between the amide and hydroxamic acid groups...
January 10, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28070001/neuroimaging-biomarkers-predict-brain-structural-connectivity-change-in-a-mouse-model-of-vascular-cognitive-impairment
#5
Philipp Boehm-Sturm, Martina Füchtemeier, Marco Foddis, Susanne Mueller, Rebecca C Trueman, Marietta Zille, Jan Leo Rinnenthal, Theodore Kypraios, Laurence Shaw, Ulrich Dirnagl, Tracy D Farr
BACKGROUND AND PURPOSE: Chronic hypoperfusion in the mouse brain has been suggested to mimic aspects of vascular cognitive impairment, such as white matter damage. Although this model has attracted attention, our group has struggled to generate a reliable cognitive and pathological phenotype. This study aimed to identify neuroimaging biomarkers of brain pathology in aged, more severely hypoperfused mice. METHODS: We used magnetic resonance imaging to characterize brain degeneration in mice hypoperfused by refining the surgical procedure to use the smallest reported diameter microcoils (160 μm)...
January 9, 2017: Stroke; a Journal of Cerebral Circulation
https://www.readbyqxmd.com/read/28066844/tight-graph-framelets-for-sparse-diffusion-mri-q-space-representation
#6
Pew-Thian Yap, Bin Dong, Yong Zhang, Dinggang Shen
In diffusion MRI, the outcome of estimation problems can often be improved by taking into account the correlation of diffusion-weighted images scanned with neighboring wavevectors in q-space. For this purpose, we propose in this paper to employ tight wavelet frames constructed on non-flat domains for multi-scale sparse representation of diffusion signals. This representation is well suited for signals sampled regularly or irregularly, such as on a grid or on multiple shells, in q-space. Using spectral graph theory, the frames are constructed based on quasi-affine systems (i...
October 2016: Medical Image Computing and Computer-assisted Intervention: MICCAI ..
https://www.readbyqxmd.com/read/28066709/alterations-of-white-matter-structural-networks-in-patients-with-non-neuropsychiatric-systemic-lupus-erythematosus-identified-by-probabilistic-tractography-and-connectivity-based-analyses
#7
Man Xu, Xiangliang Tan, Xinyuan Zhang, Yihao Guo, Yingjie Mei, Qianjin Feng, Yikai Xu, Yanqiu Feng
PURPOSE: Systemic lupus erythematosus (SLE) is a chronic inflammatory female-predominant autoimmune disease that can affect the central nervous system and exhibit neuropsychiatric symptoms. In SLE patients without neuropsychiatric symptoms (non-NPSLE), recent diffusion tensor imaging studies showed white matter abnormalities in their brains. The present study investigated the entire brain white matter structural connectivity in non-NPSLE patients by using probabilistic tractography and connectivity-based analyses...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28065848/viewing-socio-affective-stimuli-increases-connectivity-within-an-extended-default-mode-network
#8
Martin Göttlich, Zheng Ye, Antoni Rodriguez-Fornells, Thomas F Münte, Ulrike M Krämer
Empathy is an essential ability for prosocial behavior. Previous imaging studies identified a number of brain regions implicated in affective and cognitive aspects of empathy. In this study, we investigated the neural correlates of empathy from a network perspective using graph theory and beta-series correlations. Two independent data sets were acquired using the same paradigm that elicited empathic responses to socio-affective stimuli. One data set was used to define the network nodes and modular structure, the other data set was used to investigate the effects of emotional versus neutral stimuli on network connectivity...
January 5, 2017: NeuroImage
https://www.readbyqxmd.com/read/28053546/comparing-efficacy-and-survivals-of-initial-treatments-for-elderly-patients-with-newly-diagnosed-multiple-myeloma-a-network-meta-analysis-of-randomized-controlled-trials
#9
Xiaoping Liu, Jiarui Chen, Yuncen A He, Xiangyu Meng, Kaili Li, Colin K He, Shangqin Liu
OBJECTIVE: The aim of this study was to evaluate the efficacy and clinical outcome of initial therapies for elderly patients with multiple myeloma (MM). METHODS: Randomized controlled trials (RCTs) were obtained through a comprehensive search. Response rate, progression-free survival (PFS) and overall survival (OS) were the interested outcome measures. Network meta-analysis (NMA) using graph theory methodology to construct an NMA model, and sensitivity analysis were performed...
2017: OncoTargets and Therapy
https://www.readbyqxmd.com/read/28050344/structural-networks-involved-in-attention-and-executive-functions-in-multiple-sclerosis
#10
Sara Llufriu, Eloy Martinez-Heras, Elisabeth Solana, Nuria Sola-Valls, Maria Sepulveda, Yolanda Blanco, Elena H Martinez-Lapiscina, Magi Andorra, Pablo Villoslada, Alberto Prats-Galino, Albert Saiz
Attention and executive deficits are disabling symptoms in multiple sclerosis (MS) that have been related to disconnection mechanisms. We aimed to investigate changes in structural connectivity in MS and their association with attention and executive performance applying an improved framework that combines high order probabilistic tractography and anatomical exclusion criteria postprocessing. We compared graph theory metrics of structural networks and fractional anisotropy (FA) of white matter (WM) connections or edges between 72 MS subjects and 38 healthy volunteers (HV) and assessed their correlation with cognition...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28045789/imaging-and-measurement-of-the-preretinal-space-in-vitreomacular-adhesion-and-vitreomacular-traction-by-a-new-spectral-domain-optical-coherence-tomography-analysis
#11
Marcin Stopa, Elżbieta Marciniak, Piotr Rakowicz, Agnieszka Stankiewicz, Tomasz Marciniak, Adam Dąbrowski
PURPOSE: To evaluate a new method for volumetric imaging of the preretinal space (also known as the subhyaloid, subcortical, or retrocortical space) and investigate differences in preretinal space volume in vitreomacular adhesion (VMA) and vitreomacular traction (VMT). METHODS: Nine patients with VMA and 13 with VMT were prospectively evaluated. Automatic inner limiting membrane line segmentation, which exploits graph search theory implementation, and posterior cortical vitreous line segmentation were performed on 141 horizontal spectral domain optical coherence tomography B-scans per patient...
December 30, 2016: Retina
https://www.readbyqxmd.com/read/28033566/towards-a-holistic-cortical-thickness-descriptor-heat-kernel-based-grey-matter-morphology-signatures
#12
Gang Wang, Yalin Wang
In this paper, we propose a heat kernel based regional shape descriptor that may be capable of better exploiting volumetric morphological information than other available methods, thereby improving statistical power on brain magnetic resonance imaging (MRI) analysis. The mechanism of our analysis is driven by the graph spectrum and the heat kernel theory, to capture the volumetric geometry information in the constructed tetrahedral meshes. In order to capture profound brain grey matter shape changes, we first use the volumetric Laplace-Beltrami operator to determine the point pair correspondence between white-grey matter and CSF-grey matter boundary surfaces by computing the streamlines in a tetrahedral mesh...
December 26, 2016: NeuroImage
https://www.readbyqxmd.com/read/28031150/functional-dysconnection-of-the-inferior-frontal-gyrus-in-young-people-with-bipolar-disorder-or-at-genetic-high-risk
#13
Gloria Roberts, Anton Lord, Andrew Frankland, Adam Wright, Phoebe Lau, Florence Levy, Rhoshel K Lenroot, Philip B Mitchell, Michael Breakspear
BACKGROUND: Bipolar disorder (BD) is characterized by a dysregulation of affect and impaired integration of emotion with cognition. These traits are also expressed in probands at high genetic risk of BD. The inferior frontal gyrus (IFG) is a key cortical hub in the circuits of emotion and cognitive control, and it has been frequently associated with BD. Here, we studied resting-state functional connectivity of the left IFG in participants with BD and in those at increased genetic risk...
August 18, 2016: Biological Psychiatry
https://www.readbyqxmd.com/read/28029725/epicenters-of-dynamic-connectivity-in-the-adaptation-of-the-ventral-visual-system
#14
Vesna Prčkovska, Willem Huijbers, Aaron Schultz, Laura Ortiz-Teran, Cleofe Peña-Gomez, Pablo Villoslada, Keith Johnson, Reisa Sperling, Jorge Sepulcre
OBJECTIVES AND DESIGN: Neuronal responses adapt to familiar and repeated sensory stimuli. Enhanced synchrony across wide brain systems has been postulated as a potential mechanism for this adaptation phenomenon. Here, we used recently developed graph theory methods to investigate hidden connectivity features of dynamic synchrony changes during a visual repetition paradigm. Particularly, we focused on strength connectivity changes occurring at local and distant brain neighborhoods. PRINCIPAL OBSERVATIONS: We found that connectivity reorganization in visual modal cortex-such as local suppressed connectivity in primary visual areas and distant suppressed connectivity in fusiform areas-is accompanied by enhanced local and distant connectivity in higher cognitive processing areas in multimodal and association cortex...
December 28, 2016: Human Brain Mapping
https://www.readbyqxmd.com/read/28028716/evaluation-of-the-health-status-of-six-volunteers-from-the-mars-500-project-using-pulse-analysis
#15
Hong-Zhi Shi, Quan-Chun Fan, Jian-Yi Gao, Jun-Lian Liu, Gui-E Bai, Tao Mi, Shuang Zhao, Yu Liu, Dong Xu, Zhi-Feng Guo, Yong-Zhi Li
OBJECTIVE: To comprehensively evaluate the health status of 6 volunteers from the Mars 500 Project through analyzing their pulse graphs and determining the changes in cardiovascular function, degree of fatigue and autonomic nervous function. METHODS: Six volunteers were recruited; all were male aged 26-38 years (average 31.83±4.96 years). Characteristic parameters reflflecting the status of cardiovascular functions were extracted, which included left ventricular contraction, vascular elasticity and peripheral resistance...
December 27, 2016: Chinese Journal of Integrative Medicine
https://www.readbyqxmd.com/read/28025334/minimizing-proteome-redundancy-in-the-uniprot-knowledgebase
#16
Borisas Bursteinas, Ramona Britto, Benoit Bely, Andrea Auchincloss, Catherine Rivoire, Nicole Redaschi, Claire O'Donovan, Maria Jesus Martin
Advances in high-throughput sequencing have led to an unprecedented growth in genome sequences being submitted to biological databases. In particular, the sequencing of large numbers of nearly identical bacterial genomes during infection outbreaks and for other large-scale studies has resulted in a high level of redundancy in nucleotide databases and consequently in the UniProt Knowledgebase (UniProtKB). Redundancy negatively impacts on database searches by causing slower searches, an increase in statistical bias and cumbersome result analysis...
2016: Database: the Journal of Biological Databases and Curation
https://www.readbyqxmd.com/read/28018208/global-efficiency-of-structural-networks-mediates-cognitive-control-in-mild-cognitive-impairment
#17
Rok Berlot, Claudia Metzler-Baddeley, M Arfan Ikram, Derek K Jones, Michael J O'Sullivan
Background: Cognitive control has been linked to both the microstructure of individual tracts and the structure of whole-brain networks, but their relative contributions in health and disease remain unclear. Objective: To determine the contribution of both localized white matter tract damage and disruption of global network architecture to cognitive control, in older age and Mild Cognitive Impairment (MCI). Materials and Methods: Twenty-five patients with MCI and 20 age, sex, and intelligence-matched healthy volunteers were investigated with 3 Tesla structural magnetic resonance imaging (MRI)...
2016: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/28018183/changed-hub-and-corresponding-functional-connectivity-of-subgenual-anterior-cingulate-cortex-in-major-depressive-disorder
#18
Huawang Wu, Hui Sun, Jinping Xu, Yan Wu, Chao Wang, Jing Xiao, Shenglin She, Jianwei Huang, Wenjin Zou, Hongjun Peng, Xiaobing Lu, Guimao Huang, Tianzi Jiang, Yuping Ning, Jiaojian Wang
Major depressive disorder (MDD) is one of the most prevalent mental disorders. In the brain, the hubs of the brain network play a key role in integrating and transferring information between different functional modules. However, whether the changed pattern in functional network hubs contributes to the onset of MDD remains unclear. Using resting-state functional magnetic resonance imaging (rs-fMRI) and graph theory methods, we investigated whether alterations of hubs can be detected in MDD. First, we constructed the whole-brain voxel-wise functional networks and calculated a functional connectivity strength (FCS) map in each subject in 34 MDD patients and 34 gender-, age- and education level-matched healthy controls (HCs)...
2016: Frontiers in Neuroanatomy
https://www.readbyqxmd.com/read/28004143/elementary-proof-of-convergence-to-the-mean-field-model-for-the-sir-process
#19
Benjamin Armbruster, Ekkehard Beck
The susceptible-infected-recovered (SIR) model has been used extensively to model disease spread and other processes. Despite the widespread usage of this ordinary differential equation (ODE) based model which represents the mean-field approximation of the underlying stochastic SIR process on contact networks, only few rigorous approaches exist and these use complex semigroup and martingale techniques to prove that the expected fraction of the susceptible and infected nodes of the stochastic SIR process on a complete graph converges as the number of nodes increases to the solution of the mean-field ODE model...
December 21, 2016: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/27993006/classical-challenges-in-the-physical-chemistry-of-polymer-networks-and-the-design-of-new-materials
#20
Rui Wang, Michelle K Sing, Reginald K Avery, Bruno S Souza, Minkyu Kim, Bradley D Olsen
Polymer networks are widely used from commodity to biomedical materials. The space-spanning, net-like structure gives polymer networks their advantageous mechanical and dynamic properties, the most essential factor that governs their responses to external electrical, thermal, and chemical stimuli. Despite the ubiquity of applications and a century of active research on these materials, the way that chemistry and processing interact to yield the final structure and the material properties of polymer networks is not fully understood, which leads to a number of classical challenges in the physical chemistry of gels...
December 20, 2016: Accounts of Chemical Research
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