Networks play an important role in many engineering and applied problems such as water or gas transport in pipe networks, electric distributions, river basins, etc. They also represent a key concept in several biological contexts such as vascular networks, metabolic reaction networks, epidemiology, etc. In our group, we are mainly interested in networks for pipe flow distribution systems, micro-vascular networks perfusion distribution, and metabolic reaction modeling. 
Regarding pipe flow distribution and blood flow modeling, many issues are of interest, including pressure and flow distribution modeling, pressure pulsed wave propagation and heat or mass transport inside these networks, relationships between applied conditions and flow distributions, etc.
The first step consists in characterizing the structural properties of these graphs. For vascular networks, it necessitates performing 3D image distributions as well as image post-processing and 3D reconstruction of skeletonized vessels.
These very complex structural networks being known, their simplification or the resulting identification of structural and functional units are of great interest in many contexts.
Modeling of flow and transport in these networks have many application domains.
For many years, we have developed specific tissue preparation and imaging techniques for 3D high-resolution imaging of micro-vascular networks using X-ray tomography or laser sheet microscopy (Plouraboué et al. 2004, Kennel et al. 2020). We have also developed specific imaging analysis post-processing to fill gaps in interrupted vessel imaging (Risser et al. J. Biomedical imaging).
We then found structural units associated with:
- specific functions in brain tissue, i.e. robustness and compensatory distribution of blood in primate cerebral cortex (Guibert et al. 2010)
- specific browning abilities in fat tissue lobules (Dichamp et al. 2019). We also found, using graph clustering techniques, an objective procedure to identify fat lobules as strong clustering perfusion units.
Recently, we analysed how to find the source of a singular event leading to a pressure wave propagating in a graph, by pressure signal detection at various location using a few sensors distributed inside the network.
In the future we would like to adapt and develop source identification in networks for various applications, and also develop methods to address heat and mass transport inside these complex networks.
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Dynamic invasion of clusters in adipose tissue
Publications
2022
Plouraboue, Franck; Uszes, Pierre; Guibert, Romain
Source identification of propagating waves inside a network Journal Article
In: IEEE Transactions on Network Science and Engineering, pp. 1-1, 2022, ISSN: 2327-4697.
Abstract | Links | BibTeX | Altmetric
@article{9714021,
title = {Source identification of propagating waves inside a network},
author = {Franck Plouraboue and Pierre Uszes and Romain Guibert},
doi = {10.1109/TNSE.2022.3144647},
issn = {2327-4697},
year = {2022},
date = {2022-02-14},
journal = {IEEE Transactions on Network Science and Engineering},
pages = {1-1},
abstract = {The localization of short events arising within a network subsequently leading to wave propagation into it, is of interest in many applications. This work extend [1] which demonstrated the identifiability of a source from two detectors in a N nodes graph. We show that, rather than a source, a boundary condition identification is also possible and demonstrate a generalyzed unicity result. Furthermore, we extend the identification algorithm proposed in [1] to an arbitrary number of sensors, and estimate its complexity which depends on sensors number $N_s$ and time dicretisation $N_t$. Increasing detectors number increases source identification robustness to noise up to a cut-off number being a small raction of N. This cutt-off detector density for efficiency in noise reduction is of practical significance. We also analyze and discuss the method sensitivity to total recording time $T_e$, sampling frequency, and signal to noise ratio. Finally we propose a pre-sectorisation to improve the systematic exploration algorithm proposed in [1] and we show a $O(N)$ drop in complexity leading to a $O(N^3)$ cost for the source identification. Several tests of the method on model and real graphs confirm and support the presented results.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The localization of short events arising within a network subsequently leading to wave propagation into it, is of interest in many applications. This work extend [1] which demonstrated the identifiability of a source from two detectors in a N nodes graph. We show that, rather than a source, a boundary condition identification is also possible and demonstrate a generalyzed unicity result. Furthermore, we extend the identification algorithm proposed in [1] to an arbitrary number of sensors, and estimate its complexity which depends on sensors number $N_s$ and time dicretisation $N_t$. Increasing detectors number increases source identification robustness to noise up to a cut-off number being a small raction of N. This cutt-off detector density for efficiency in noise reduction is of practical significance. We also analyze and discuss the method sensitivity to total recording time $T_e$, sampling frequency, and signal to noise ratio. Finally we propose a pre-sectorisation to improve the systematic exploration algorithm proposed in [1] and we show a $O(N)$ drop in complexity leading to a $O(N^3)$ cost for the source identification. Several tests of the method on model and real graphs confirm and support the presented results.
2021
Aceves-Sanchez, Pedro; Aymard, Benjamin; Peurichard, Diane; Kennel, Pol; Lorsignol, Anne; Plouraboué, Franck; Casteilla, Louis; Degond, Pierre
A new model for the emergence of blood capillary networks Journal Article
In: Networks & Heterogeneous Media, 16 (1), pp. 91–138, 2021.
Abstract | Links | BibTeX | Altmetric
@article{oatao27422,
title = {A new model for the emergence of blood capillary networks},
author = {Pedro Aceves-Sanchez and Benjamin Aymard and Diane Peurichard and Pol Kennel and Anne Lorsignol and Franck Plouraboué and Louis Casteilla and Pierre Degond},
url = {https://oatao.univ-toulouse.fr/27422/},
doi = {10.3934/nhm.2021001},
year = {2021},
date = {2021-03-01},
journal = {Networks & Heterogeneous Media},
volume = {16},
number = {1},
pages = {91--138},
publisher = {American Institute of Sciences Mathematical},
abstract = {We propose a new model for the emergence of blood capillary networks. We assimilate the tissue and extra cellular matrix as a porous medium, using Darcy's law for describing both blood and interstitial fluid flows. Oxygen obeys a convection-diffusion-reaction equation describing advection by the blood, diffusion and consumption by the tissue. Discrete agents named capillary elements and modelling groups of endothelial cells are created or deleted according to different rules involving the oxygen concentration gradient, the blood velocity, the sheer stress or the capillary element density. Once created, a capillary element locally enhances the hydraulic conductivity matrix, contributing to a local increase of the blood velocity and oxygen flow. No connectivity between the capillary elements is imposed. The coupling between blood, oxygen flow and capillary elements provides a positive feedback mechanism which triggers the emergence of a network of channels of high hydraulic conductivity which we identify as new blood capillaries. We provide two different, biologically relevant geometrical settings and numerically analyze the influence of each of the capillary creation mechanism in detail. All mechanisms seem to concur towards a harmonious network but the most important ones are those involving oxygen gradient and sheer stress. A detailed discussion of this model with respect to the literature and its potential future developments concludes the paper.},
keywords = {},
pubstate = {published},
tppubtype = {article}
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We propose a new model for the emergence of blood capillary networks. We assimilate the tissue and extra cellular matrix as a porous medium, using Darcy’s law for describing both blood and interstitial fluid flows. Oxygen obeys a convection-diffusion-reaction equation describing advection by the blood, diffusion and consumption by the tissue. Discrete agents named capillary elements and modelling groups of endothelial cells are created or deleted according to different rules involving the oxygen concentration gradient, the blood velocity, the sheer stress or the capillary element density. Once created, a capillary element locally enhances the hydraulic conductivity matrix, contributing to a local increase of the blood velocity and oxygen flow. No connectivity between the capillary elements is imposed. The coupling between blood, oxygen flow and capillary elements provides a positive feedback mechanism which triggers the emergence of a network of channels of high hydraulic conductivity which we identify as new blood capillaries. We provide two different, biologically relevant geometrical settings and numerically analyze the influence of each of the capillary creation mechanism in detail. All mechanisms seem to concur towards a harmonious network but the most important ones are those involving oxygen gradient and sheer stress. A detailed discussion of this model with respect to the literature and its potential future developments concludes the paper.
2020
Kennel, Pol; Dichamp, Jules; Barreau, Corinne; Guissard, Christophe; Teyssedre, Lise; Rouquette, Jacques; Colombelli, Julien; Lorsignol, Anne; Casteilla, Louis; Plouraboué, Franck
From whole-organ imaging to in-silico blood flow modeling: a new multi-scale network analysis for revisiting tissue functional anatomy Journal Article
In: PLOS Computational Biology, 16 (2), pp. e1007322, 2020.
Abstract | Links | BibTeX | Altmetric
@article{oatao25659,
title = {From whole-organ imaging to in-silico blood flow modeling: a new multi-scale network analysis for revisiting tissue functional anatomy},
author = {Pol Kennel and Jules Dichamp and Corinne Barreau and Christophe Guissard and Lise Teyssedre and Jacques Rouquette and Julien Colombelli and Anne Lorsignol and Louis Casteilla and Franck Plouraboué},
url = {https://oatao.univ-toulouse.fr/25659/},
doi = {10.1371/journal.pcbi.1007322},
year = {2020},
date = {2020-02-01},
urldate = {2020-02-01},
journal = {PLOS Computational Biology},
volume = {16},
number = {2},
pages = {e1007322},
abstract = {We present a multi-disciplinary image-based blood flow perfusion modeling of a whole organ vascular network for analyzing both its structural and functional properties. We show how the use of Light-Sheet Fluorescence Microscopy (LSFM) permits whole-organ micro- vascular imaging, analysis and modelling. By using adapted image post-treatment workflow, we could segment, vectorize and reconstruct the entire micro-vascular network composed of 1.7 million vessels, from the tissue-scale, inside a * 25 × 5 × 1 = 125mm3 volume of the mouse fat pad, hundreds of times larger than previous studies, down to the cellular scale at micron resolution, with the entire blood perfusion modeled. Adapted network analysis revealed the structural and functional organization of meso-scale tissue as strongly connected communities of vessels. These communities share a distinct heterogeneous core region and a more homogeneous peripheral region, consistently with known biological functions of fat tissue. Graph clustering analysis also revealed two distinct robust meso-scale typical sizes (from 10 to several hundred times the cellular size), revealing, for the first time, strongly connected functional vascular communities. These community networks support heterogeneous micro-environments. This work provides the proof of concept that in-silico all-tissue perfusion modeling can reveal new structural and functional exchanges between micro-regions in tissues, found from community clusters in the vascular graph.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a multi-disciplinary image-based blood flow perfusion modeling of a whole organ vascular network for analyzing both its structural and functional properties. We show how the use of Light-Sheet Fluorescence Microscopy (LSFM) permits whole-organ micro- vascular imaging, analysis and modelling. By using adapted image post-treatment workflow, we could segment, vectorize and reconstruct the entire micro-vascular network composed of 1.7 million vessels, from the tissue-scale, inside a * 25 × 5 × 1 = 125mm3 volume of the mouse fat pad, hundreds of times larger than previous studies, down to the cellular scale at micron resolution, with the entire blood perfusion modeled. Adapted network analysis revealed the structural and functional organization of meso-scale tissue as strongly connected communities of vessels. These communities share a distinct heterogeneous core region and a more homogeneous peripheral region, consistently with known biological functions of fat tissue. Graph clustering analysis also revealed two distinct robust meso-scale typical sizes (from 10 to several hundred times the cellular size), revealing, for the first time, strongly connected functional vascular communities. These community networks support heterogeneous micro-environments. This work provides the proof of concept that in-silico all-tissue perfusion modeling can reveal new structural and functional exchanges between micro-regions in tissues, found from community clusters in the vascular graph.
2019
Dichamp, Jules; Barreau, Corinne; Guissard, Christophe; Carrière, Audrey; Martinez, Yves; Descombes, Xavier; Pénicaud, Luc; Rouquette, Jacques; Casteilla, Louis; Plouraboué, Franck; Lorsignol, Anne
In: Scientific Reports, 9 , pp. 1–13, 2019.
Abstract | Links | BibTeX | Altmetric
@article{oatao23852,
title = {3D analysis of the whole subcutaneous adipose tissue reveals a complex spatial network of interconnected lobules with heterogeneous browning ability},
author = {Jules Dichamp and Corinne Barreau and Christophe Guissard and Audrey Carrière and Yves Martinez and Xavier Descombes and Luc Pénicaud and Jacques Rouquette and Louis Casteilla and Franck Plouraboué and Anne Lorsignol},
url = {https://rdcu.be/bRNp0
https://oatao.univ-toulouse.fr/23852/},
doi = {10.1038/s41598-019-43130-9},
year = {2019},
date = {2019-04-01},
urldate = {2019-04-01},
journal = {Scientific Reports},
volume = {9},
pages = {1--13},
publisher = {Nature Publishing Group},
abstract = {Adipose tissue, as the main energy storage organ and through its endocrine activity, is interconnected with all physiological functions. It plays a fundamental role in energy homeostasis and in the development of metabolic disorders. Up to now, this tissue has been analysed as a pool of different cell types with very little attention paid to the organization and putative partitioning of cells. Considering the absence of a complete picture of the intimate architecture of this large soft tissue, we developed a method that combines tissue clearing, acquisition of autofluorescence or lectin signals by confocal microscopy, segmentation procedures based on contrast enhancement, and a new semi-automatic image analysis process, allowing accurate and quantitative characterization of the whole 3D fat pad organization. This approach revealed the unexpected anatomic complexity of the murine subcutaneous fat pad. Although the classical picture of adipose tissue corresponds to a superposition of simple and small ellipsoidal lobules of adipose cells separated by mesenchymal spans, our results show that segmented lobules display complex 3D poly-lobular shapes. Despite differences in shape and size, the number of these poly-lobular subunits is similar from one fat pad to another. Finally, investigation of the relationships of these subunits between each other revealed a never-described organization in two clusters with distinct molecular signatures and specific vascular and sympathetic nerve densities correlating with different browning abilities. This innovative procedure reveals that subcutaneous adipose tissue exhibits a subtle functional heterogeneity with partitioned areas, and opens new perspectives towards understanding its functioning and plasticity.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Adipose tissue, as the main energy storage organ and through its endocrine activity, is interconnected with all physiological functions. It plays a fundamental role in energy homeostasis and in the development of metabolic disorders. Up to now, this tissue has been analysed as a pool of different cell types with very little attention paid to the organization and putative partitioning of cells. Considering the absence of a complete picture of the intimate architecture of this large soft tissue, we developed a method that combines tissue clearing, acquisition of autofluorescence or lectin signals by confocal microscopy, segmentation procedures based on contrast enhancement, and a new semi-automatic image analysis process, allowing accurate and quantitative characterization of the whole 3D fat pad organization. This approach revealed the unexpected anatomic complexity of the murine subcutaneous fat pad. Although the classical picture of adipose tissue corresponds to a superposition of simple and small ellipsoidal lobules of adipose cells separated by mesenchymal spans, our results show that segmented lobules display complex 3D poly-lobular shapes. Despite differences in shape and size, the number of these poly-lobular subunits is similar from one fat pad to another. Finally, investigation of the relationships of these subunits between each other revealed a never-described organization in two clusters with distinct molecular signatures and specific vascular and sympathetic nerve densities correlating with different browning abilities. This innovative procedure reveals that subcutaneous adipose tissue exhibits a subtle functional heterogeneity with partitioned areas, and opens new perspectives towards understanding its functioning and plasticity.
2018
Kennel, Pol; Teyssedre, Lise; Colombelli, Julien; Plouraboué, Franck
Toward quantitative three-dimensional microvascular networks segmentation with multiview light-sheet fluorescence microscopy Journal Article
In: Journal of Biomedical Optics, 23 (08), pp. 1–15, 2018.
Abstract | Links | BibTeX | Altmetric
@article{oatao20743,
title = {Toward quantitative three-dimensional microvascular networks segmentation with multiview light-sheet fluorescence microscopy},
author = {Pol Kennel and Lise Teyssedre and Julien Colombelli and Franck Plouraboué},
url = {https://oatao.univ-toulouse.fr/20743/},
doi = {10.1117/1.JBO.23.8.086002},
year = {2018},
date = {2018-08-01},
journal = {Journal of Biomedical Optics},
volume = {23},
number = {08},
pages = {1--15},
publisher = {Society of Photo-optical Instrumentation Engineers},
abstract = {Three-dimensional (3-D) large-scale imaging of microvascular networks is of interest in various areas of biology and medicine related to structural, functional, developmental, and pathological issues. Light-sheet fluorescence microscopy (LSFM) techniques are rapidly spreading and are now on the way to offer operational solutions for large-scale tissue imaging. This contribution describes how reliable vessel segmentation can be handled from LSFM data in very large tissue volumes using a suitable image analysis workflow. Since capillaries are tubular objects of a few microns scale radius, they represent challenging structures to reliably reconstruct without distortion and artifacts. We provide a systematic analysis of multiview deconvolution image processing workflow to control and evaluate the accuracy of the reconstructed vascular network using various low to high level, metrics. We show that even if low-level structural metrics are sensitive to isotropic imaging enhancement provided by a larger number of views, functional high-level metrics, including perfusion permeability, are less sensitive. Hence, combining deconvolution and registration onto a few number of views appears sufficient for a reliable quantitative 3-D vessel segmentation for their possible use for perfusion modeling.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Three-dimensional (3-D) large-scale imaging of microvascular networks is of interest in various areas of biology and medicine related to structural, functional, developmental, and pathological issues. Light-sheet fluorescence microscopy (LSFM) techniques are rapidly spreading and are now on the way to offer operational solutions for large-scale tissue imaging. This contribution describes how reliable vessel segmentation can be handled from LSFM data in very large tissue volumes using a suitable image analysis workflow. Since capillaries are tubular objects of a few microns scale radius, they represent challenging structures to reliably reconstruct without distortion and artifacts. We provide a systematic analysis of multiview deconvolution image processing workflow to control and evaluate the accuracy of the reconstructed vascular network using various low to high level, metrics. We show that even if low-level structural metrics are sensitive to isotropic imaging enhancement provided by a larger number of views, functional high-level metrics, including perfusion permeability, are less sensitive. Hence, combining deconvolution and registration onto a few number of views appears sufficient for a reliable quantitative 3-D vessel segmentation for their possible use for perfusion modeling.
2017
Kennel, Pol; Fonta, Caroline; Guibert, Romain; Plouraboué, Franck
Analysis of vascular homogeneity and anisotropy on high-resolution primate brain imaging Online
2017, visited: 01.01.2017.
Abstract | Links | BibTeX | Altmetric
@online{oatao18367,
title = {Analysis of vascular homogeneity and anisotropy on high-resolution primate brain imaging},
author = {Pol Kennel and Caroline Fonta and Romain Guibert and Franck Plouraboué},
url = {http://onlinelibrary.wiley.com/doi/10.1002/hbm.23766/abstract
https://oatao.univ-toulouse.fr/18367/},
doi = {10.1002/hbm.23766},
year = {2017},
date = {2017-01-01},
urldate = {2017-01-01},
journal = {Human Brain Mapping},
pages = {1--22},
publisher = {Wiley},
abstract = {Using a systematic investigation of brain blood volume, in high-resolution synchrotron 3D images of microvascular structures within cortical regions of a primate brain, we challenge several basic questions regarding possible vascular bias in high-resolution functional neuroimaging. We present a bilateral comparison of cortical regions, where we analyze relative vascular volume in voxels from 150 to 1000 lm side lengths in the white and grey matter. We show that, if voxel size reaches a scale smaller than 300 mm, the vascular volume can no longer be considered homogeneous, either within one hemisphere or in bilateral comparison between samples. We demonstrate that voxel size influences the comparison between vessel-relative volume distributions depending on the scale considered (i.e., hemisphere, lobe, or sample). Furthermore, we also investigate how voxel anisotropy and orientation can affect the apparent vascular volume, in accordance with actual fMRI voxel sizes. These findings are discussed from the various perspectives of high-resolution brain functional imaging},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
Using a systematic investigation of brain blood volume, in high-resolution synchrotron 3D images of microvascular structures within cortical regions of a primate brain, we challenge several basic questions regarding possible vascular bias in high-resolution functional neuroimaging. We present a bilateral comparison of cortical regions, where we analyze relative vascular volume in voxels from 150 to 1000 lm side lengths in the white and grey matter. We show that, if voxel size reaches a scale smaller than 300 mm, the vascular volume can no longer be considered homogeneous, either within one hemisphere or in bilateral comparison between samples. We demonstrate that voxel size influences the comparison between vessel-relative volume distributions depending on the scale considered (i.e., hemisphere, lobe, or sample). Furthermore, we also investigate how voxel anisotropy and orientation can affect the apparent vascular volume, in accordance with actual fMRI voxel sizes. These findings are discussed from the various perspectives of high-resolution brain functional imaging
2016
Barreau, Corinne; Labit, Elodie; Guissard, Christophe; Rouquette, Jacques; Boizeau, Marie-Laure; Koumassi, Souleymane Gani; Carrière, Audrey; Jeanson, Yannick; Berger-Müller, Sandra; Dromard, Cécile; Plouraboué, Franck; Casteilla, Louis; Lorsignol, Anne
Regionalization of browning revealed by whole subcutaneous adipose tissue imaging Journal Article
In: Obesity, 00 (00), pp. 1–9, 2016.
Abstract | Links | BibTeX | Altmetric
@article{oatao15674,
title = {Regionalization of browning revealed by whole subcutaneous adipose tissue imaging},
author = {Corinne Barreau and Elodie Labit and Christophe Guissard and Jacques Rouquette and Marie-Laure Boizeau and Souleymane Gani Koumassi and Audrey Carrière and Yannick Jeanson and Sandra Berger-Müller and Cécile Dromard and Franck Plouraboué and Louis Casteilla and Anne Lorsignol},
url = {http://onlinelibrary.wiley.com/doi/10.1002/oby.21455/full
https://oatao.univ-toulouse.fr/15674/},
doi = {10.1002/oby.21455},
year = {2016},
date = {2016-03-01},
urldate = {2016-03-01},
journal = {Obesity},
volume = {00},
number = {00},
pages = {1--9},
publisher = {Wiley},
abstract = {Objective: White and brown adipose tissues play a major role in the regulation of metabolic functions. With the explosion of obesity and metabolic disorders, the interest in adipocyte biology is growing constantly. While several studies have demonstrated functional differences between adipose fat pads, especially in their involvement in metabolic diseases, there are no data available on possible heterogeneity within an adipose depot.
Methods: This study investigated the three-dimensional (3-D) organization of the inguinal fat pad in adult mice by combining adipose tissue clearing and autofluorescence signal acquisition by confocal microscopy. In addition, the study analyzed the expression of genes involved in adipocyte biology and browning at the mARN and protein levels in distinct areas of the inguinal adipose tissue, in control conditions and after cold exposure.
Results: Semiautomated 3-D image analysis revealed an organization of the fat depot showing two regions: the core was structured into segmented lobules, whereas the periphery appeared unsegmented. Perilipin immunostaining showed that most of the adipocytes located in the core region had smaller lipid droplets, suggesting a brown-like phenotype. qPCR analysis showed a higher expression of the browning markers Ucp1, Prdm16, Ppargc1a, and Cidea in the core region than at the periphery. Finally, cold exposure induced upregulation of thermogenic gene expression associated with an increase of UCP1 protein, specifically in the core region of the inguinal fat depot.
Conclusions: Altogether, these data demonstrate a structural and functional heterogeneity of the inguinal fat pad, with an anatomically restricted browning process in the core area.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Objective: White and brown adipose tissues play a major role in the regulation of metabolic functions. With the explosion of obesity and metabolic disorders, the interest in adipocyte biology is growing constantly. While several studies have demonstrated functional differences between adipose fat pads, especially in their involvement in metabolic diseases, there are no data available on possible heterogeneity within an adipose depot.
Methods: This study investigated the three-dimensional (3-D) organization of the inguinal fat pad in adult mice by combining adipose tissue clearing and autofluorescence signal acquisition by confocal microscopy. In addition, the study analyzed the expression of genes involved in adipocyte biology and browning at the mARN and protein levels in distinct areas of the inguinal adipose tissue, in control conditions and after cold exposure.
Results: Semiautomated 3-D image analysis revealed an organization of the fat depot showing two regions: the core was structured into segmented lobules, whereas the periphery appeared unsegmented. Perilipin immunostaining showed that most of the adipocytes located in the core region had smaller lipid droplets, suggesting a brown-like phenotype. qPCR analysis showed a higher expression of the browning markers Ucp1, Prdm16, Ppargc1a, and Cidea in the core region than at the periphery. Finally, cold exposure induced upregulation of thermogenic gene expression associated with an increase of UCP1 protein, specifically in the core region of the inguinal fat depot.
Conclusions: Altogether, these data demonstrate a structural and functional heterogeneity of the inguinal fat pad, with an anatomically restricted browning process in the core area.
Methods: This study investigated the three-dimensional (3-D) organization of the inguinal fat pad in adult mice by combining adipose tissue clearing and autofluorescence signal acquisition by confocal microscopy. In addition, the study analyzed the expression of genes involved in adipocyte biology and browning at the mARN and protein levels in distinct areas of the inguinal adipose tissue, in control conditions and after cold exposure.
Results: Semiautomated 3-D image analysis revealed an organization of the fat depot showing two regions: the core was structured into segmented lobules, whereas the periphery appeared unsegmented. Perilipin immunostaining showed that most of the adipocytes located in the core region had smaller lipid droplets, suggesting a brown-like phenotype. qPCR analysis showed a higher expression of the browning markers Ucp1, Prdm16, Ppargc1a, and Cidea in the core region than at the periphery. Finally, cold exposure induced upregulation of thermogenic gene expression associated with an increase of UCP1 protein, specifically in the core region of the inguinal fat depot.
Conclusions: Altogether, these data demonstrate a structural and functional heterogeneity of the inguinal fat pad, with an anatomically restricted browning process in the core area.
2013
Guibert, Romain; Fonta, Caroline; Estève, François; Plouraboué, Franck
On the normalization of cerebral blood flow Journal Article
In: Journal of Cerebral Blood Flow & Metabolism, 33 , pp. 669–672, 2013.
Abstract | Links | BibTeX | Altmetric
@article{oatao8933,
title = {On the normalization of cerebral blood flow},
author = {Romain Guibert and Caroline Fonta and François Estève and Franck Plouraboué},
url = {www.nature.com/jcbfm/journal/v33/n5/full/jcbfm201339a.html
https://oatao.univ-toulouse.fr/8933/},
doi = {10.1038/jcbfm.2013.39},
year = {2013},
date = {2013-05-01},
urldate = {2013-05-01},
journal = {Journal of Cerebral Blood Flow & Metabolism},
volume = {33},
pages = {669--672},
publisher = {Nature Publishing Group},
abstract = {Cerebral blood ?ow (CBF) is the most common parameter for the quanti?cation of brain?s function. Literature data indicate a widespread dispersion of values that might be related to some differences in the measurement conditions that are not properly taken into account in CBF evaluation. Using recent high-resolution imaging of the complete cortical microvasculature of primate brain, we perform extensive numerical evaluation of the cerebral perfusion. We show that blood perfusion associated with intravascular tracers should be normalized by the surface of the voxel rather than by its volume and we consistently test this result on the available literature data.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cerebral blood ?ow (CBF) is the most common parameter for the quanti?cation of brain?s function. Literature data indicate a widespread dispersion of values that might be related to some differences in the measurement conditions that are not properly taken into account in CBF evaluation. Using recent high-resolution imaging of the complete cortical microvasculature of primate brain, we perform extensive numerical evaluation of the cerebral perfusion. We show that blood perfusion associated with intravascular tracers should be normalized by the surface of the voxel rather than by its volume and we consistently test this result on the available literature data.
2012
Bardan, Gérald; Plouraboué, Franck; Zagzoule, Mokhtar; Balédent, Olivier
Simple Patient-Based Transmantle Pressure and Shear Estimate From Cine Phase-Contrast MRI in Cerebral Aqueduct Journal Article
In: IEEE Transactions on Biomedical Engineering, 59 (10), pp. 2874–2883, 2012.
Abstract | Links | BibTeX | Altmetric
@article{oatao6572,
title = {Simple Patient-Based Transmantle Pressure and Shear Estimate From Cine Phase-Contrast MRI in Cerebral Aqueduct},
author = {Gérald Bardan and Franck Plouraboué and Mokhtar Zagzoule and Olivier Balédent},
url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6263280
https://oatao.univ-toulouse.fr/6572/},
doi = {10.1109/TBME.2012.2210716},
year = {2012},
date = {2012-10-01},
urldate = {2012-10-01},
journal = {IEEE Transactions on Biomedical Engineering},
volume = {59},
number = {10},
pages = {2874--2883},
publisher = {IEEE},
abstract = {From measurements of the oscillating flux of the cerebrospinal fluid (CSF) in the aqueduct of Sylvius, we elaborate a patient-based methodology for transmantle pressure (TRP) and shear evaluation. High-resolution anatomical magnetic resonance imaging first permits a precise 3-D anatomical digitalized reconstruction of the Sylvius aqueduct shape. From this, a very fast approximate numerical flow computation, nevertheless consistent with analytical predictions, is developed. Our approach includes the main contributions of inertial effects coming from the pulsatile flow and curvature effects associated with the aqueduct bending. Integrating the pressure along the aqueduct longitudinal center-line enables the total dynamic hydraulic admittances of the aqueduct to be evaluated, which is the pre-eminent contribution to the CSF pressure difference between the lateral ventricles and the subarachnoidal spaces also called the TRP. The application of the method to 20 healthy human patients validates the hypothesis of the proposed approach and provides a first database for normal aqueduct CSF flow. Finally, the implications of our results for modeling and evaluating intracranial cerebral pressure are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
From measurements of the oscillating flux of the cerebrospinal fluid (CSF) in the aqueduct of Sylvius, we elaborate a patient-based methodology for transmantle pressure (TRP) and shear evaluation. High-resolution anatomical magnetic resonance imaging first permits a precise 3-D anatomical digitalized reconstruction of the Sylvius aqueduct shape. From this, a very fast approximate numerical flow computation, nevertheless consistent with analytical predictions, is developed. Our approach includes the main contributions of inertial effects coming from the pulsatile flow and curvature effects associated with the aqueduct bending. Integrating the pressure along the aqueduct longitudinal center-line enables the total dynamic hydraulic admittances of the aqueduct to be evaluated, which is the pre-eminent contribution to the CSF pressure difference between the lateral ventricles and the subarachnoidal spaces also called the TRP. The application of the method to 20 healthy human patients validates the hypothesis of the proposed approach and provides a first database for normal aqueduct CSF flow. Finally, the implications of our results for modeling and evaluating intracranial cerebral pressure are discussed.
Guibert, Romain; Fonta, Caroline; Risser, Laurent; Plouraboué, Franck
Coupling and robustness of intra-cortical vascular territories Journal Article
In: NeuroImage, 62 (1), pp. 408–417, 2012.
Abstract | Links | BibTeX | Altmetric
@article{oatao6021,
title = {Coupling and robustness of intra-cortical vascular territories},
author = {Romain Guibert and Caroline Fonta and Laurent Risser and Franck Plouraboué},
url = {http://www.sciencedirect.com/science/article/pii/S1053811912004260
https://oatao.univ-toulouse.fr/6021/},
doi = {10.1016/j.neuroimage.2012.04.030},
year = {2012},
date = {2012-08-01},
urldate = {2012-08-01},
journal = {NeuroImage},
volume = {62},
number = {1},
pages = {408--417},
publisher = {Elsevier},
abstract = {Vascular domains have been described as being coupled to neuronal functional units enabling dynamic blood supply to the cerebral cyto-architecture. Recent experiments have shown that penetrating arterioles of the grey matter are the building blocks for such units. Nevertheless, vascular territories are still poorly known, as the collection and analysis of large three-dimensional micro-vascular networks are difficult. By using an exhaustive reconstruction of the micro-vascular network in an 18 mm 3 volume of marmoset cerebral cortex, we numerically computed the blood flow in each blood vessel. We thus defined arterial and venular territories and examined their overlap. A large part of the intracortical vascular network was found to be supplied by several arteries and drained by several venules. We quantified this multiple potential to compensate for deficiencies by introducing a new robustness parameter. Robustness proved to be positively correlated with cortical depth and a systematic investigation of coupling maps indicated local patterns of overlap between neighbouring arteries and neighbouring venules. However, arterio-venular coupling did not have a spatial pattern of overlap but showed locally preferential functional coupling, especially of one artery with two venules, supporting the notion of vascular units. We concluded that intra-cortical perfusion in the primate was characterised by both very narrow functional beds and a large capacity for compensatory redistribution, far beyond the nearest neighbour collaterals.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Vascular domains have been described as being coupled to neuronal functional units enabling dynamic blood supply to the cerebral cyto-architecture. Recent experiments have shown that penetrating arterioles of the grey matter are the building blocks for such units. Nevertheless, vascular territories are still poorly known, as the collection and analysis of large three-dimensional micro-vascular networks are difficult. By using an exhaustive reconstruction of the micro-vascular network in an 18 mm 3 volume of marmoset cerebral cortex, we numerically computed the blood flow in each blood vessel. We thus defined arterial and venular territories and examined their overlap. A large part of the intracortical vascular network was found to be supplied by several arteries and drained by several venules. We quantified this multiple potential to compensate for deficiencies by introducing a new robustness parameter. Robustness proved to be positively correlated with cortical depth and a systematic investigation of coupling maps indicated local patterns of overlap between neighbouring arteries and neighbouring venules. However, arterio-venular coupling did not have a spatial pattern of overlap but showed locally preferential functional coupling, especially of one artery with two venules, supporting the notion of vascular units. We concluded that intra-cortical perfusion in the primate was characterised by both very narrow functional beds and a large capacity for compensatory redistribution, far beyond the nearest neighbour collaterals.
Descombes, Xavier; Plouraboué, Franck; Boustani, Abdelhakim El; Fonta, Caroline; Duc, Géraldine Le; Serduc, Raphael; Weitkamp, Timm
Vascular network segmentation: an unsupervised approach Inproceedings
In: 9th IEEE International Symposium on Biomedical Imaging 2012 – ISBI, pp. 1248–1251, Barcelona, ES, 2012.
Abstract | Links | BibTeX | Altmetric
@inproceedings{oatao9193,
title = {Vascular network segmentation: an unsupervised approach},
author = {Xavier Descombes and Franck Plouraboué and Abdelhakim El Boustani and Caroline Fonta and Géraldine Le Duc and Raphael Serduc and Timm Weitkamp},
url = {https://oatao.univ-toulouse.fr/9193/},
doi = {10.1109/ISBI.2012.6235788},
year = {2012},
date = {2012-01-01},
urldate = {2012-01-01},
booktitle = {9th IEEE International Symposium on Biomedical Imaging 2012 - ISBI},
pages = {1248--1251},
address = {Barcelona, ES},
abstract = {Micro-tomography produces high resolution images of biological structures such as vascular networks. In this paper, we present a new approach for segmenting vascular network into pathological and normal regions from considering their micro-vessel 3D structure only. We consider a partition of the volume obtained by a watershed algorithm based on the distance from the nearest vessel. Each territory is characterized by its volume and the local vascular density. The volume and density maps are first regularized by minimizing the total variation. Then, a new approach is proposed to segment the volume from the two previous restored images based on hypothesis testing. Results are presented on 3D micro-tomographic images of the brain micro-vascular network.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Micro-tomography produces high resolution images of biological structures such as vascular networks. In this paper, we present a new approach for segmenting vascular network into pathological and normal regions from considering their micro-vessel 3D structure only. We consider a partition of the volume obtained by a watershed algorithm based on the distance from the nearest vessel. Each territory is characterized by its volume and the local vascular density. The volume and density maps are first regularized by minimizing the total variation. Then, a new approach is proposed to segment the volume from the two previous restored images based on hypothesis testing. Results are presented on 3D micro-tomographic images of the brain micro-vascular network.
2011
Guibert, Romain; Fonta, Caroline; Plouraboué, Franck
From cerebral blood flow modeling to vascular units map in primate cortex Inproceedings
In: EUROMECH Colloquium 521 – Biomedical Flows at Low Reynolds Numbers, Zurich, CH, 2011.
@inproceedings{oatao10542,
title = {From cerebral blood flow modeling to vascular units map in primate cortex},
author = {Romain Guibert and Caroline Fonta and Franck Plouraboué},
url = {http://e-collection.library.ethz.ch/eserv/eth:3019/eth-3019-01.pdf
https://oatao.univ-toulouse.fr/10542/},
year = {2011},
date = {2011-01-01},
urldate = {2011-01-01},
booktitle = {EUROMECH Colloquium 521 - Biomedical Flows at Low Reynolds Numbers},
address = {Zurich, CH},
abstract = {The amazing topological and geometrical complexity of micro-vascular networks in the brain, and in other organs, has challenged many researchers for decades. Since the brain's vascular system is structured by a highly reticulated pial surface network which plunges down into a set of penetrating vessels, it is tempting to attribute a vascular unit to each penetrating arteriole. Recent experimental analysis have led to a breakthrough on the properties of the blood supply in the brain. Penetrating arterioles have been identified as the bottleneck of brain perfusion. Furthermore, it has also been realized that targeted clots of penetrating arterioles are not compensated by active changes in the diameter of their neighbor arteries. This observation suggests passive compensatory mechanisms resulting from the couplings between arteriolar territories consistent with other recent observations of active blood flow reorganization via collateral vessels (inter-arterial connections). A systematic investigation of the three-dimensional extent of compensation is not possible with experimental measurements but in silico simulations permit a systematic investigation of the spatial distribution of the brain perfusion.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The amazing topological and geometrical complexity of micro-vascular networks in the brain, and in other organs, has challenged many researchers for decades. Since the brain’s vascular system is structured by a highly reticulated pial surface network which plunges down into a set of penetrating vessels, it is tempting to attribute a vascular unit to each penetrating arteriole. Recent experimental analysis have led to a breakthrough on the properties of the blood supply in the brain. Penetrating arterioles have been identified as the bottleneck of brain perfusion. Furthermore, it has also been realized that targeted clots of penetrating arterioles are not compensated by active changes in the diameter of their neighbor arteries. This observation suggests passive compensatory mechanisms resulting from the couplings between arteriolar territories consistent with other recent observations of active blood flow reorganization via collateral vessels (inter-arterial connections). A systematic investigation of the three-dimensional extent of compensation is not possible with experimental measurements but in silico simulations permit a systematic investigation of the spatial distribution of the brain perfusion.
Descombes, Xavier; Plouraboué, Franck; Boustani, Abdelhakim El; Fonta, Caroline; Leduc, Géraldine; Serduc, Raphael; Weitkamp, Timm
Brain Tumor Vascular Network Segmentation from Micro-Tomography Inproceedings
In: 2011 IEEE International Symposium on Biomedical Imaging, pp. 1113–1116, Chicago, USA, 2011.
Abstract | Links | BibTeX | Altmetric
@inproceedings{oatao5015,
title = {Brain Tumor Vascular Network Segmentation from Micro-Tomography},
author = {Xavier Descombes and Franck Plouraboué and Abdelhakim El Boustani and Caroline Fonta and Géraldine Leduc and Raphael Serduc and Timm Weitkamp},
url = {https://oatao.univ-toulouse.fr/5015/},
doi = {10.1109/ISBI.2011.5872596},
year = {2011},
date = {2011-01-01},
urldate = {2011-01-01},
booktitle = {2011 IEEE International Symposium on Biomedical Imaging},
pages = {1113--1116},
address = {Chicago, USA},
abstract = {Micro-tomography produces high resolution images of bio- logical structures such as vascular networks. In this paper, we present a new approach for segmenting vascular network into pathological and normal regions from considering their micro-vessel 3D structure only. We de?ne and use a condi- tional random ?eld for segmenting the output of a watershed algorithm. The tumoral and normal classes are thus character- ized by their respective distribution of watershed region size interpreted as local vascular territories.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Micro-tomography produces high resolution images of bio- logical structures such as vascular networks. In this paper, we present a new approach for segmenting vascular network into pathological and normal regions from considering their micro-vessel 3D structure only. We de?ne and use a condi- tional random ?eld for segmenting the output of a watershed algorithm. The tumoral and normal classes are thus character- ized by their respective distribution of watershed region size interpreted as local vascular territories.
2010
Guibert, Romain; Fonta, Caroline; Plouraboué, Franck
Cerebral blood flow modeling in primate cortex Journal Article
In: Journal of Cerebral Blood Flow & Metabolism, 30 (11), pp. 1860–1873, 2010.
Abstract | Links | BibTeX | Altmetric
@article{oatao5466,
title = {Cerebral blood flow modeling in primate cortex},
author = {Romain Guibert and Caroline Fonta and Franck Plouraboué},
url = {http://www.nature.com/jcbfm/journal/v30/n11/full/jcbfm2010105a.html
https://oatao.univ-toulouse.fr/5466/},
doi = {10.1038/jcbfm.2010.105},
year = {2010},
date = {2010-07-01},
urldate = {2010-07-01},
journal = {Journal of Cerebral Blood Flow & Metabolism},
volume = {30},
number = {11},
pages = {1860--1873},
publisher = {Nature Publishing Group},
abstract = {We report new results on blood flow modeling over large volumes of cortical gray matter of primate brain. We propose a network method for computing the blood flow, which handles realistic boundary conditions, complex vessel shapes, and complex nonlinear blood rheology. From a detailed comparison of the available models for the blood flow rheology and the phase separation effect, we are able to derive important new results on the impact of network structure on blood pressure, hematocrit, and flow distributions. Our findings show that the network geometry (vessel shapes and diameters), the boundary conditions associated with the arterial inputs and venous outputs, and the effective viscosity of the blood are essential components in the flow distribution. In contrast, we show that the phase separation effect has a minor function in the global microvascular hemodynamic behavior. The behavior of the pressure, hematocrit, and blood flow distributions within the network are described through the depth of the primate cerebral cortex and are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report new results on blood flow modeling over large volumes of cortical gray matter of primate brain. We propose a network method for computing the blood flow, which handles realistic boundary conditions, complex vessel shapes, and complex nonlinear blood rheology. From a detailed comparison of the available models for the blood flow rheology and the phase separation effect, we are able to derive important new results on the impact of network structure on blood pressure, hematocrit, and flow distributions. Our findings show that the network geometry (vessel shapes and diameters), the boundary conditions associated with the arterial inputs and venous outputs, and the effective viscosity of the blood are essential components in the flow distribution. In contrast, we show that the phase separation effect has a minor function in the global microvascular hemodynamic behavior. The behavior of the pressure, hematocrit, and blood flow distributions within the network are described through the depth of the primate cerebral cortex and are discussed.
Guibert, Romain; Fonta, Caroline; Plouraboué, Franck
A New Approach to Model Confined Suspensions Flows in Complex Networks: Application to Blood Flow Journal Article
In: Transport in Porous Media, 83 (1), pp. 171–194, 2010.
Abstract | Links | BibTeX | Altmetric
@article{oatao5459,
title = {A New Approach to Model Confined Suspensions Flows in Complex Networks: Application to Blood Flow},
author = {Romain Guibert and Caroline Fonta and Franck Plouraboué},
url = {http://www.springerlink.com/content/kj72721r5783638w/?MUD=MP
https://oatao.univ-toulouse.fr/5459/},
doi = {10.1007/s11242-009-9492-0},
year = {2010},
date = {2010-01-01},
urldate = {2010-01-01},
journal = {Transport in Porous Media},
volume = {83},
number = {1},
pages = {171--194},
publisher = {Springer},
abstract = {The modeling of blood flows confined in micro-channels or micro-capillary beds depends on the interactions between the cell-phase, plasma and the complex geometry of the network. In the case of capillaries or channels having a high aspect ratio (their longitudinal size is much larger than their transverse one), this modeling is much simplified from the use of a continuous description of fluid viscosity as previously proposed in the literature. Phase separation or plasma skimming effect is a supplementary mechanism responsible for the relative distribution of the red blood cell's volume density in each branch of a given bifurcation. Different models have already been proposed to connect this effect to the various hydrodynamics and geometrical parameters at each bifurcation. We discuss the advantages and drawbacks of these models and compare them to an alternative approach for modeling phase distribution in complex channels networks. The main novelty of this new formulation is to show that albeit all the previous approaches seek for a local origin of the phase segregation phenomenon, it can arise from a global non-local and nonlinear structuration of the flow inside the network. This new approach describes how elementary conservation laws are sufficient principles (rather than the complex arametric models previously proposed) to provide non local phase separation. Spatial variations of the hematocrit field thus result from the topological complexity of the network as well as nonlinearities arising from solving a new free boundary problem associated with the ?ux and mass conservation. This network model approach could apply to model blood flow distribution either on arti?cial micro-models, micro-fluidic networks, or realistic reconstruction of biological micro-vascular networks.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The modeling of blood flows confined in micro-channels or micro-capillary beds depends on the interactions between the cell-phase, plasma and the complex geometry of the network. In the case of capillaries or channels having a high aspect ratio (their longitudinal size is much larger than their transverse one), this modeling is much simplified from the use of a continuous description of fluid viscosity as previously proposed in the literature. Phase separation or plasma skimming effect is a supplementary mechanism responsible for the relative distribution of the red blood cell’s volume density in each branch of a given bifurcation. Different models have already been proposed to connect this effect to the various hydrodynamics and geometrical parameters at each bifurcation. We discuss the advantages and drawbacks of these models and compare them to an alternative approach for modeling phase distribution in complex channels networks. The main novelty of this new formulation is to show that albeit all the previous approaches seek for a local origin of the phase segregation phenomenon, it can arise from a global non-local and nonlinear structuration of the flow inside the network. This new approach describes how elementary conservation laws are sufficient principles (rather than the complex arametric models previously proposed) to provide non local phase separation. Spatial variations of the hematocrit field thus result from the topological complexity of the network as well as nonlinearities arising from solving a new free boundary problem associated with the ?ux and mass conservation. This network model approach could apply to model blood flow distribution either on arti?cial micro-models, micro-fluidic networks, or realistic reconstruction of biological micro-vascular networks.
2009
Guibert, Romain; Fonta, Caroline; Plouraboué, Franck
Le réseau micro-vasculaire structure la distribution de la pression sanguine Journal Article
In: Mécanique & Industries, 10 (3-4), pp. 255–260, 2009.
Abstract | Links | BibTeX | Altmetric
@article{oatao9192,
title = {Le réseau micro-vasculaire structure la distribution de la pression sanguine},
author = {Romain Guibert and Caroline Fonta and Franck Plouraboué},
url = {https://www.mechanics-industry.org/articles/meca/pdf/2009/03/mi0021-2009.pdf
https://oatao.univ-toulouse.fr/9192/},
doi = {10.1051/meca/2009061},
year = {2009},
date = {2009-05-01},
urldate = {2009-05-01},
journal = {Mécanique & Industries},
volume = {10},
number = {3-4},
pages = {255--260},
publisher = {EDP Sciences},
abstract = {Cerebral micro-vascular networks control the blood pressure distribution when considering in vitro blood rheology models. Blood rheology is complex and non-linear. In small vessels, the effective viscosity variations are important due to red blood cells packing in capillaries, the so-called Frahræus-Lindquist effect, whilst concomitantly phase segregation appears in bifurcations. Direct numerical simulations of different non-linear rheological models of the blood are performed on realistic three-dimensional micro-vascular networks. These simulations exhibit two significant results. First, various rheological models lead to very similar pressure distribution over the whole range of physiologically relevant hematocrits. Secondly, different models for phase segregation lead to very distinct hematocrit distributions in the micro-vacular network. Nevertheless, the hematocrit distribution very weakly affects the pressure distribution. Hence, our results suggest that the micro-vacular network structure mainly controls the pressure distribution in micro-circulation, whilst the effect of hematocrit distribution is weak.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cerebral micro-vascular networks control the blood pressure distribution when considering in vitro blood rheology models. Blood rheology is complex and non-linear. In small vessels, the effective viscosity variations are important due to red blood cells packing in capillaries, the so-called Frahræus-Lindquist effect, whilst concomitantly phase segregation appears in bifurcations. Direct numerical simulations of different non-linear rheological models of the blood are performed on realistic three-dimensional micro-vascular networks. These simulations exhibit two significant results. First, various rheological models lead to very similar pressure distribution over the whole range of physiologically relevant hematocrits. Secondly, different models for phase segregation lead to very distinct hematocrit distributions in the micro-vacular network. Nevertheless, the hematocrit distribution very weakly affects the pressure distribution. Hence, our results suggest that the micro-vacular network structure mainly controls the pressure distribution in micro-circulation, whilst the effect of hematocrit distribution is weak.
Risser, Laurent; Plouraboué, Franck; Cloetens, Peter; Fonta, Caroline
A 3D-investigation shows that angiogenesis in primate cerebral cortex mainly occurs at capillary level Journal Article
In: International Journal of Developmental Neuroscience, 27 (2), pp. 185–196, 2009.
Abstract | Links | BibTeX | Altmetric
@article{oatao5464,
title = {A 3D-investigation shows that angiogenesis in primate cerebral cortex mainly occurs at capillary level},
author = {Laurent Risser and Franck Plouraboué and Peter Cloetens and Caroline Fonta},
url = {http://www.sciencedirect.com/science/journal/07365748
https://oatao.univ-toulouse.fr/5464/},
doi = {10.1016/j.ijdevneu.2008.10.006},
year = {2009},
date = {2009-04-01},
urldate = {2009-04-01},
journal = {International Journal of Developmental Neuroscience},
volume = {27},
number = {2},
pages = {185--196},
publisher = {Elsevier},
abstract = {This paper describes the use of a new 3D high-resolution imaging technique dedicated to functional vessels for a systematic quantitative study of angiogenesis in the primate cortex. We present a new method which permits, using synchrotron X-ray micro-tomography imaging, the identi?cation of micro-vascular components as well as their automatic numerical digitalization and extraction from very large 3D image analysis and post-treatments. This method is used to analyze various levels of micro-vascular
organization and their postnatal modi?cations. Comparing newborn- and adult marmosets, we found an increase in vascular volume (270%), exchange surface (260%) and vessel length (290%) associated to a decrease in distances between vessel and tissue (32%). The increase in relative vascular volumes between the two ages, examined through the whole cortical depth, has been found to be mainly sustained by
events occurring at the capillary level, and only marginally at the perforating vessel level. This work
shows that the postnatal cortical maturation classically described in terms of synaptogenesis, gliogenesis and connectivity plasticity is accompanied by an intensive remodeling of micro-vascular patterns.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper describes the use of a new 3D high-resolution imaging technique dedicated to functional vessels for a systematic quantitative study of angiogenesis in the primate cortex. We present a new method which permits, using synchrotron X-ray micro-tomography imaging, the identi?cation of micro-vascular components as well as their automatic numerical digitalization and extraction from very large 3D image analysis and post-treatments. This method is used to analyze various levels of micro-vascular
organization and their postnatal modi?cations. Comparing newborn- and adult marmosets, we found an increase in vascular volume (270%), exchange surface (260%) and vessel length (290%) associated to a decrease in distances between vessel and tissue (32%). The increase in relative vascular volumes between the two ages, examined through the whole cortical depth, has been found to be mainly sustained by
events occurring at the capillary level, and only marginally at the perforating vessel level. This work
shows that the postnatal cortical maturation classically described in terms of synaptogenesis, gliogenesis and connectivity plasticity is accompanied by an intensive remodeling of micro-vascular patterns.
organization and their postnatal modi?cations. Comparing newborn- and adult marmosets, we found an increase in vascular volume (270%), exchange surface (260%) and vessel length (290%) associated to a decrease in distances between vessel and tissue (32%). The increase in relative vascular volumes between the two ages, examined through the whole cortical depth, has been found to be mainly sustained by
events occurring at the capillary level, and only marginally at the perforating vessel level. This work
shows that the postnatal cortical maturation classically described in terms of synaptogenesis, gliogenesis and connectivity plasticity is accompanied by an intensive remodeling of micro-vascular patterns.
2008
Risser, Laurent; Plouraboué, Franck; Descombes, Xavier
Gap Filling of 3-D Microvascular Networks by Tensor Voting Journal Article
In: IEEE Transactions on Medical Imaging, 27 (5), pp. 674–687, 2008.
Abstract | Links | BibTeX | Altmetric
@article{oatao5469,
title = {Gap Filling of 3-D Microvascular Networks by Tensor Voting},
author = {Laurent Risser and Franck Plouraboué and Xavier Descombes},
url = {https://oatao.univ-toulouse.fr/5469/
https://ieeexplore.ieee.org/document/4389807},
doi = {10.1109/TMI.2007.913248},
year = {2008},
date = {2008-01-01},
urldate = {2008-01-01},
journal = {IEEE Transactions on Medical Imaging},
volume = {27},
number = {5},
pages = {674--687},
publisher = {Institute of Electrical and Electronics Engineers},
abstract = {We present a new algorithm which merges discontinuities in 3-D images of tubular structures presenting undesirable gaps. The application of the proposed method is mainly associated to large 3-D images of microvascular networks. In order to recover the real network topology, we need to fill the gaps between the closest discontinuous vessels. The algorithm presented in this paper aims at achieving this goal. This algorithm is based on the skeletonization of the segmented network followed by a tensor voting method. It permits to merge the most common kinds of discontinuities found in microvascular networks. It is robust, easy to use, and relatively fast. The microvascular network images were obtained using synchrotron tomography imaging at the European Synchrotron Radiation Facility. These images exhibit samples of intracortical networks. Representative results are illustrated.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a new algorithm which merges discontinuities in 3-D images of tubular structures presenting undesirable gaps. The application of the proposed method is mainly associated to large 3-D images of microvascular networks. In order to recover the real network topology, we need to fill the gaps between the closest discontinuous vessels. The algorithm presented in this paper aims at achieving this goal. This algorithm is based on the skeletonization of the segmented network followed by a tensor voting method. It permits to merge the most common kinds of discontinuities found in microvascular networks. It is robust, easy to use, and relatively fast. The microvascular network images were obtained using synchrotron tomography imaging at the European Synchrotron Radiation Facility. These images exhibit samples of intracortical networks. Representative results are illustrated.
2006
Risser, Laurent; Plouraboué, Franck; Steyer, Alexandre; Cloetens, Peter; Duc, Géraldine Le; Fonta, Caroline
From homogeneous to fractal normal and tumorous microvascular networks in the brain Journal Article
In: Journal of Cerebral Blood Flow and Metabolism, 27 (2), pp. 293–303, 2006, (Thanks to Nature Publishing group. This article is available at http://www.nature.com/jcbfm/index.html).
Abstract | Links | BibTeX | Altmetric
@article{oatao5477,
title = {From homogeneous to fractal normal and tumorous microvascular networks in the brain},
author = {Laurent Risser and Franck Plouraboué and Alexandre Steyer and Peter Cloetens and Géraldine Le Duc and Caroline Fonta},
url = {https://oatao.univ-toulouse.fr/5477/},
doi = {10.1038/sj.jcbfm.9600332},
year = {2006},
date = {2006-01-01},
journal = {Journal of Cerebral Blood Flow and Metabolism},
volume = {27},
number = {2},
pages = {293--303},
publisher = {Nature Publishing Group},
abstract = {We studied normal and tumorous three-dimensional (3D) microvascular networks in primate and rat brain. Tissues were prepared following a new preparation technique intended for high-resolution synchrotron tomography of microvascular networks. The resulting 3D images with a spatial resolution of less than the minimum capillary diameter permit a complete description of the entire vascular network for volumes as large as tens of cubic millimeters. The structural properties of the vascular networks were investigated by several multiscale methods such as fractal and power-spectrum analysis. These investigations gave a new coherent picture of normal and pathological complex vascular structures. They showed that normal cortical vascular networks have scale-invariant fractal properties on a small scale from 1.4 lm up to 40 to 65 lm. Above this threshold, vascular networks can be considered as homogeneous. Tumor vascular networks show similar characteristics, but the validity range of the fractal regime extend to much larger spatial dimensions.
These 3D results shed new light on previous two dimensional analyses giving for the first time a
direct measurement of vascular modules associated with vessel-tissue surface exchange.},
note = {Thanks to Nature Publishing group. This article is available at http://www.nature.com/jcbfm/index.html},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We studied normal and tumorous three-dimensional (3D) microvascular networks in primate and rat brain. Tissues were prepared following a new preparation technique intended for high-resolution synchrotron tomography of microvascular networks. The resulting 3D images with a spatial resolution of less than the minimum capillary diameter permit a complete description of the entire vascular network for volumes as large as tens of cubic millimeters. The structural properties of the vascular networks were investigated by several multiscale methods such as fractal and power-spectrum analysis. These investigations gave a new coherent picture of normal and pathological complex vascular structures. They showed that normal cortical vascular networks have scale-invariant fractal properties on a small scale from 1.4 lm up to 40 to 65 lm. Above this threshold, vascular networks can be considered as homogeneous. Tumor vascular networks show similar characteristics, but the validity range of the fractal regime extend to much larger spatial dimensions.
These 3D results shed new light on previous two dimensional analyses giving for the first time a
direct measurement of vascular modules associated with vessel-tissue surface exchange.
These 3D results shed new light on previous two dimensional analyses giving for the first time a
direct measurement of vascular modules associated with vessel-tissue surface exchange.
2004
Plouraboué, Franck; Cloetens, Peter; Fonta, Caroline; Steyer, Alexandre; Lauwers, Frédéric; Marc-Vergnes, J. P
X-ray high-resolution vascular network imaging Journal Article
In: Journal of Microscopy, 215 (2), pp. 139–148, 2004.
Abstract | Links | BibTeX | Altmetric
@article{oatao5483,
title = {X-ray high-resolution vascular network imaging},
author = {Franck Plouraboué and Peter Cloetens and Caroline Fonta and Alexandre Steyer and Frédéric Lauwers and J. P Marc-Vergnes},
url = {https://oatao.univ-toulouse.fr/5483/},
doi = {10.1111/j.0022-2720.2004.01362.x},
year = {2004},
date = {2004-08-01},
urldate = {2004-08-01},
journal = {Journal of Microscopy},
volume = {215},
number = {2},
pages = {139--148},
publisher = {Wiley},
abstract = {This paper presents the first application of high-resolution X-ray synchrotron tomography to the imaging of large micro-vascular networks in biological tissue samples. This technique offers the opportunity of analysing the full three-dimensional vascular network from the micrometre to the millimetre scale.
This paper presents the specific sample preparation method and the X-ray imaging procedure. Either barium or iron was injected as contrast agent in the vascular network. The impact of the composition and concentration of the injected solution on the X-ray synchrotron tomography images has been studied. Two imaging modes, attenuation and phase contrast, are compared. Synchrotron high-resolution computed tomography offers new prospects in the three-dimensional imaging of in situ biological vascular networks.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper presents the first application of high-resolution X-ray synchrotron tomography to the imaging of large micro-vascular networks in biological tissue samples. This technique offers the opportunity of analysing the full three-dimensional vascular network from the micrometre to the millimetre scale.
This paper presents the specific sample preparation method and the X-ray imaging procedure. Either barium or iron was injected as contrast agent in the vascular network. The impact of the composition and concentration of the injected solution on the X-ray synchrotron tomography images has been studied. Two imaging modes, attenuation and phase contrast, are compared. Synchrotron high-resolution computed tomography offers new prospects in the three-dimensional imaging of in situ biological vascular networks.
This paper presents the specific sample preparation method and the X-ray imaging procedure. Either barium or iron was injected as contrast agent in the vascular network. The impact of the composition and concentration of the injected solution on the X-ray synchrotron tomography images has been studied. Two imaging modes, attenuation and phase contrast, are compared. Synchrotron high-resolution computed tomography offers new prospects in the three-dimensional imaging of in situ biological vascular networks.