Cluster analysis in kinetic modelling of the brain: a noninvasive alternative to arterial sampling

NeuroImage ◽  
2004 ◽  
Vol 21 (2) ◽  
pp. 483-493 ◽  
Author(s):  
Matthew Liptrot ◽  
Karen H Adams ◽  
Lars Martiny ◽  
Lars H Pinborg ◽  
Markus N Lonsdale ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Kinetic Modelling ◽  
Arterial Sampling ◽  
The Brain

scholarly journals Modelling [18F]LW223 PET data using simplified imaging protocols for quantification of TSPO expression in the rat heart and brain

2021 ◽  
Author(s):  
Mark G. MacAskill ◽  
Catriona Wimberley ◽  
Timaeus E. F. Morgan ◽  
Carlos J. Alcaide-Corral ◽  
David E. Newby ◽  
...  
Keyword(s):  
Outcome Measures ◽  
Pet Imaging ◽  
Kinetic Modelling ◽  
Input Function ◽  
Binding Potential ◽  
Coronary Artery Ligation ◽  
Systematic Bias ◽  
Arterial Blood ◽  
The Brain ◽  
Tspo Expression

Abstract Purpose To provide a comprehensive assessment of the novel 18 kDa translocator protein (TSPO) radiotracer, [18F]LW223, kinetics in the heart and brain when using a simplified imaging approach. Methods Naive adult rats and rats with surgically induced permanent coronary artery ligation received a bolus intravenous injection of [18F]LW223 followed by 120 min PET scanning with arterial blood sampling throughout. Kinetic modelling of PET data was applied to estimated rate constants, total volume of distribution (VT) and binding potential transfer corrected (BPTC) using arterial or image-derived input function (IDIF). Quantitative bias of simplified protocols using IDIF versus arterial input function (AIF) and stability of kinetic parameters for PET imaging data of different length (40–120 min) were estimated. Results PET outcome measures estimated using IDIF significantly correlated with those derived with invasive AIF, albeit with an inherent systematic bias. Truncation of the dynamic PET scan duration to less than 100 min reduced the stability of the kinetic modelling outputs. Quantification of [18F]LW223 uptake kinetics in the brain and heart required the use of different outcome measures, with BPTC more stable in the heart and VT more stable in the brain. Conclusion Modelling of [18F]LW223 PET showed the use of simplified IDIF is acceptable in the rat and the minimum scan duration for quantification of TSPO expression in rats using kinetic modelling with this radiotracer is 100 min. Carefully assessing kinetic outcome measures when conducting a systems level as oppose to single-organ centric analyses is crucial. This should be taken into account when assessing the emerging role of the TSPO heart-brain axis in the field of PET imaging.

scholarly journals Analysis of limb movement synchronization in primates locomotion

2018 ◽  
Vol 81 (4) ◽  
pp. 414-422
Author(s):  
Zofia Sikorska-Piwowska ◽  
Piotr Śliwka ◽  
Bogdan Ciszek
Keyword(s):  
Mathematical Model ◽  
Cluster Analysis ◽  
Hierarchical Cluster Analysis ◽  
Hierarchical Cluster ◽  
Evolution Process ◽  
Discrete Variables ◽  
Phylogenetic Relations ◽  
Proposed Model ◽  
The Brain ◽  
Movement Synchronization

Abstract The authors present an original mathematical model based on features identified with discrete variables using vector and hierarchical cluster analysis in primates locomotion. Proposed model allows to formalize and analyze the synchronization variability of movements in given locomotion types of adaptation and specialization in monkeys, apes and humans. The material covers observations of 102 forms including 9 species of primates: the chimpanzee, bonobo, orangutan, gibbon, gelada, mandrill, brown capuchin and ring–tailed lemur. The studies included also the synchronization of locomotory movements in man. The sequences of moves of pectoral and pelvic limbs, right and left, were studied in four categories: walking, running, jumping and brachiation. The locomotion movements depend on the brain centers and allow to find phylogenetic relations between examined forms in the evolution process. The knowledge of the pattern of movements is used in the treatment of paraplegia and paraparesis in humans.

scholarly journals Analyzing Microarray Data of Alzheimer's Using Cluster Analysis to Identify the Biomarker Genes

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Satya vani Guttula ◽  
Apparao Allam ◽  
R. Sridhar Gumpeny
Keyword(s):  
Cluster Analysis ◽  
Microarray Data ◽  
Senile Plaques ◽  
Dynamic Change ◽  
Hierarchical Cluster ◽  
Gene Expression Omnibus ◽  
The Other ◽  
Cortical Regions ◽  
The Brain ◽  
Over Time

Alzheimer is characterized by the presence of senile plaques and neurofibrillary tangles in cortical regions of the brain. The experimental data is taken from Gene Expression Omnibus. A hierarchical Cluster analysis and TreeView were performed to group genes on the basis of the expression pattern. The dynamic change of expression over time and diverse patterns of expression support the concept of a complex local milieu. TreeView allows the organized data to be visualized. List of 24 genes were obtained which showed high expression levels. Three genes, SORL1, APP, and APOE, are suspected to cause Alzheimer’s whereas the other 21 genes are related to other diseases but may also be found to be associated with Alzheimer’s, and these are TMEM59, CCT4, IGF2R, SFPQ, PRDX3, RNF14, IDS, SSBP1, SYNE2, TXNL4A, STXBP3, SMARCB1, ULK2, AGTPBP1, FABP7, CALB1, H2AFY, COPA, SAP18, ATIC and SYNCRIP.

scholarly journals The desensitization pathway of GABAA receptors, one subunit at a time

2020 ◽  
Author(s):  
Marc Gielen ◽  
Nathalie Barilone ◽  
Pierre-Jean Corringer
Keyword(s):  
Gabaa Receptors ◽  
Synergistic Effects ◽  
Kinetic Modelling ◽  
Concerted Mechanism ◽  
Inhibitory Synaptic Transmission ◽  
Asymmetric Pattern ◽  
Gaba Binding ◽  
Conformational Landscape ◽  
Fast Activation ◽  
The Brain

AbstractGABAA receptors mediate most inhibitory synaptic transmission in the brain of vertebrates. Following GABA binding and fast activation, these receptors undergo a slower desensitization, whose conformational pathway remains largely elusive. To explore the mechanism of desensitization, we used concatemeric α1β2γ2 GABAA receptors to selectively introduce gain-of-desensitization mutations one subunit at a time. A library of twenty-six mutant combinations was generated and their bi-exponential macroscopic desensitization rates measured. Introducing mutations at the different subunits shows a strongly asymmetric pattern with a key contribution of the γ2 subunit, and combining mutations results in marked synergistic effects indicating a non-concerted mechanism. Kinetic modelling indeed suggests a pathway where subunits move independently, the desensitization of two subunits being required to occlude the pore. Our work thus hints towards a very diverse and labile conformational landscape during desensitization, with potential implications in physiology and pharmacology.

METHODS AND ALGORITHMS FOR IMAGE SEGMENTATION

2020 ◽  
Vol 2020 (2) ◽  
pp. 11-16
Author(s):  
Karina Jo ◽  
Olga Gerget
Keyword(s):  
Cluster Analysis ◽  
Image Segmentation ◽  
Brain Tumors ◽  
Medical Images ◽  
Region Growing ◽  
Segmentation Method ◽  
Segmentation Accuracy ◽  
Optimal Segmentation ◽  
The Brain

This study aim to find the optimal segmentation method for detecting brain tumors. For this purpose, the main methods from each group were selected: from stochastic-the method of cluster analysis of k-means, from structural-morphological, from mixed – region growing. The study was based on medical images of the brain, the sample includes 10 images. After segmenting the images, you need to find the best result. The result must be justified. As a result of the research, the method of region growing proved to be an effective method. The accuracy of the method is proved by statistical and variance analyses. The segmentation accuracy of the region growing is 89 %.

scholarly journals The desensitization pathway of GABAA receptors, one subunit at a time

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Marc Gielen ◽  
Nathalie Barilone ◽  
Pierre-Jean Corringer
Keyword(s):  
Gabaa Receptors ◽  
Synergistic Effects ◽  
Kinetic Modelling ◽  
Concerted Mechanism ◽  
Inhibitory Synaptic Transmission ◽  
Asymmetric Pattern ◽  
Gaba Binding ◽  
Conformational Landscape ◽  
Fast Activation ◽  
The Brain

Abstract GABAA receptors mediate most inhibitory synaptic transmission in the brain of vertebrates. Following GABA binding and fast activation, these receptors undergo a slower desensitization, the conformational pathway of which remains largely elusive. To explore the mechanism of desensitization, we used concatemeric α1β2γ2 GABAA receptors to selectively introduce gain-of-desensitization mutations one subunit at a time. A library of twenty-six mutant combinations was generated and their bi-exponential macroscopic desensitization rates measured. Introducing mutations at the different subunits shows a strongly asymmetric pattern with a key contribution of the γ2 subunit, and combining mutations results in marked synergistic effects indicating a non-concerted mechanism. Kinetic modelling indeed suggests a pathway where subunits move independently, the desensitization of two subunits being required to occlude the pore. Our work thus hints towards a very diverse and labile conformational landscape during desensitization, with potential implications in physiology and pharmacology.

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