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Béduer A, Genta M, Kunz N, Verheyen C, Martins M, Brefie-Guth J, Braschler T. Design of an elastic porous injectable biomaterial for tissue regeneration and volume retention. Acta Biomater 2022; 142:73-84. [PMID: 35101581 DOI: 10.1016/j.actbio.2022.01.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 01/01/2022] [Accepted: 01/24/2022] [Indexed: 11/01/2022]
Abstract
Soft tissue reconstruction currently relies on two main approaches, one involving the implantation of external biomaterials and the second one exploiting surgical autologous tissue displacement. While both methods have different advantages and disadvantages, successful long-term solutions for soft tissue repair are still limited. Specifically, volume retention over time and local tissue regeneration are the main challenges in the field. In this study the performance of a recently developed elastic porous injectable (EPI) biomaterial based on crosslinked carboxymethylcellulose is analyzed. Nearly quantitative volumetric stability, with over 90% volume retention at 6 months, is observed, and the pore space of the material is effectively colonized with autologous fibrovascular tissue. A comparative analysis with hyaluronic acid and collagen-based clinical reference materials is also performed. Mechanical stability, evidenced by a low-strain elastic storage modulus (G') approaching 1kPa and a yield strain of several tens of percent, is required for volume retention in-vivo. Macroporosity, along with in-vivo persistence of at least several months, is instead needed for successful host tissue colonization. This study demonstrates the importance of understanding material design criteria and defines the biomaterial requirements for volume retention and tissue colonization in soft tissue regeneration. STATEMENT OF SIGNIFICANCE: We present the design of an elastic, porous, injectable (EPI) scaffold suspension capable of inducing a precisely defined, stable volume of autologous connective tissue in situ. It combines volume stability and vascularized tissue induction capacity known from bulk scaffolds with the ease of injection in shear yielding materials. By comparative study with a series of clinically established biomaterials including a wound healing matrix and dermal fillers, we establish design rules regarding rheological and compressive mechanical properties as well as degradation characteristics that rationally underpin the volume stability and tissue induction in a high-performance biomaterial. These design rules should allow to streamline the development of new colonizable injectables.
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Canales-Rodríguez EJ, Pizzolato M, Piredda GF, Hilbert T, Kunz N, Pot C, Yu T, Salvador R, Pomarol-Clotet E, Kober T, Thiran JP, Daducci A. Comparison of non-parametric T 2 relaxometry methods for myelin water quantification. Med Image Anal 2021; 69:101959. [PMID: 33581618 DOI: 10.1016/j.media.2021.101959] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/10/2020] [Accepted: 01/04/2021] [Indexed: 02/06/2023]
Abstract
Multi-component T2 relaxometry allows probing tissue microstructure by assessing compartment-specific T2 relaxation times and water fractions, including the myelin water fraction. Non-negative least squares (NNLS) with zero-order Tikhonov regularization is the conventional method for estimating smooth T2 distributions. Despite the improved estimation provided by this method compared to non-regularized NNLS, the solution is still sensitive to the underlying noise and the regularization weight. This is especially relevant for clinically achievable signal-to-noise ratios. In the literature of inverse problems, various well-established approaches to promote smooth solutions, including first-order and second-order Tikhonov regularization, and different criteria for estimating the regularization weight have been proposed, such as L-curve, Generalized Cross-Validation, and Chi-square residual fitting. However, quantitative comparisons between the available reconstruction methods for computing the T2 distribution, and between different approaches for selecting the optimal regularization weight, are lacking. In this study, we implemented and evaluated ten reconstruction algorithms, resulting from the individual combinations of three penalty terms with three criteria to estimate the regularization weight, plus non-regularized NNLS. Their performance was evaluated both in simulated data and real brain MRI data acquired from healthy volunteers through a scan-rescan repeatability analysis. Our findings demonstrate the need for regularization. As a result of this work, we provide a list of recommendations for selecting the optimal reconstruction algorithms based on the acquired data. Moreover, the implemented methods were packaged in a freely distributed toolbox to promote reproducible research, and to facilitate further research and the use of this promising quantitative technique in clinical practice.
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Affiliation(s)
- Erick Jorge Canales-Rodríguez
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) , Barcelona, Spain; Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - Marco Pizzolato
- Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Gian Franco Piredda
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland
| | - Tom Hilbert
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland
| | - Nicolas Kunz
- Animal Imaging and Technology section, Center for Biomedical Imaging (CIBM), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Caroline Pot
- Department of Pathology and Immunology, Geneva University Hospital and University of Geneva, Geneva, Switzerland; Division of Neurology and Neuroscience Research Center, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Thomas Yu
- Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Medical Image Analysis Laboratory, Center for Biomedical Imaging (CIBM), University of Lausanne, Lausanne, Switzerland
| | - Raymond Salvador
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) , Barcelona, Spain
| | - Edith Pomarol-Clotet
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) , Barcelona, Spain
| | - Tobias Kober
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland
| | - Jean-Philippe Thiran
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Signal Processing Lab (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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Dehghani M, Kunz N, Lei H. Diffusion behavior of cerebral metabolites of congenital portal systemic shunt mice assessed noninvasively by diffusion-weighted 1 H magnetic resonance spectroscopy. NMR Biomed 2020; 33:e4198. [PMID: 31765073 DOI: 10.1002/nbm.4198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 08/27/2019] [Accepted: 09/13/2019] [Indexed: 06/10/2023]
Abstract
Diffusion-weighted 1 H-MRS (DW-MRS) allows for noninvasive investigation of the cellular compartmentalization of cerebral metabolites. DW-MRS applied to the congenital portal systemic shunt (PSS) mouse brain may provide specific insight into alterations of cellular restrictions associated with PSS in humans. At 14.1 T, adult male PSS and their age-matched healthy (Ctrl) mice were studied using DW-MRS covering b-values ranging from 0 to 45 ms/μm2 to determine the diffusion behavior of abundant metabolites. The remarkable sensitivity and spectral resolution, in combination with very high diffusion weighting, allowed for precise measurement of the diffusion properties of endogenous N-acetyl-aspartate, total creatine, myo-inositol, total choline with extension to glutamine and glutamate in mouse brains, in vivo. Most metabolites had comparable diffusion properties in PSS and Ctrl mice, suggesting that intracellular distribution space for these metabolites was not affected in the model. The slightly different diffusivity of the slow decaying component of taurine (0.015 ± 0.003 μm2 /ms in PSS vs 0.021 ± 0.002 μm2 /ms in Ctrl, P < 0.05) might support a cellular redistribution of taurine in the PSS mouse brain.
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Affiliation(s)
- Masoumeh Dehghani
- Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Psychiatry, McGill University, Montreal, Canada
| | - Nicolas Kunz
- Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Hongxia Lei
- Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Can E, Mishkovsky M, Yoshihara HAI, Kunz N, Couturier DL, Petrausch U, Doucey MA, Comment A. Noninvasive rapid detection of metabolic adaptation in activated human T lymphocytes by hyperpolarized 13C magnetic resonance. Sci Rep 2020; 10:200. [PMID: 31932697 PMCID: PMC6957688 DOI: 10.1038/s41598-019-57026-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/18/2019] [Indexed: 11/18/2022] Open
Abstract
The metabolic shift induced in human CD4+ T lymphocytes by stimulation is characterized by an upregulation of glycolysis, leading to an augmentation in lactate production. This adaptation has already been highlighted with various techniques and reported in several previous studies. We herein propose a method to rapidly and noninvasively detect the associated increase in flux from pyruvate to lactate catalyzed by lactate dehydrogenase using hyperpolarized 13C magnetic resonance, a technique which can be used for in vivo imaging. It was shown that the conversion of hyperpolarized 13C-pyruvate to 13C-lactate during the one-minute measurement increased by a mean factor of 3.6 in T cells stimulated for 5 days as compared to resting T cells. This method can be extended to other metabolic substrates and is therefore a powerful tool to noninvasively analyze T cell metabolism, possibly in vivo.
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Affiliation(s)
- Emine Can
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Mor Mishkovsky
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Hikari A I Yoshihara
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Nicolas Kunz
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Dominique-Laurent Couturier
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shin Center, Robinson Way, Cambridge, CB2 0RE, United Kingdom
| | | | - Marie-Agnès Doucey
- Department of Oncology, University Hospital Lausanne (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Arnaud Comment
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shin Center, Robinson Way, Cambridge, CB2 0RE, United Kingdom. .,General Electric Healthcare, Chalfont St Giles, Buckinghamshire, HP8 4SP, United Kingdom.
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Tratwal J, Bekri D, Boussema C, Sarkis R, Kunz N, Koliqi T, Rojas-Sutterlin S, Schyrr F, Tavakol DN, Campos V, Scheller EL, Sarro R, Bárcena C, Bisig B, Nardi V, de Leval L, Burri O, Naveiras O. MarrowQuant Across Aging and Aplasia: A Digital Pathology Workflow for Quantification of Bone Marrow Compartments in Histological Sections. Front Endocrinol (Lausanne) 2020; 11:480. [PMID: 33071956 PMCID: PMC7542184 DOI: 10.3389/fendo.2020.00480] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 06/17/2020] [Indexed: 12/12/2022] Open
Abstract
The bone marrow (BM) exists heterogeneously as hematopoietic/red or adipocytic/yellow marrow depending on skeletal location, age, and physiological condition. Mouse models and patients undergoing radio/chemotherapy or suffering acute BM failure endure rapid adipocytic conversion of the marrow microenvironment, the so-called "red-to-yellow" transition. Following hematopoietic recovery, such as upon BM transplantation, a "yellow-to-red" transition occurs and functional hematopoiesis is restored. Gold Standards to estimate BM cellular composition are pathologists' assessment of hematopoietic cellularity in hematoxylin and eosin (H&E) stained histological sections as well as volumetric measurements of marrow adiposity with contrast-enhanced micro-computerized tomography (CE-μCT) upon osmium-tetroxide lipid staining. Due to user-dependent variables, reproducibility in longitudinal studies is a challenge for both methods. Here we report the development of a semi-automated image analysis plug-in, MarrowQuant, which employs the open-source software QuPath, to systematically quantify multiple bone components in H&E sections in an unbiased manner. MarrowQuant discerns and quantifies the areas occupied by bone, adipocyte ghosts, hematopoietic cells, and the interstitial/microvascular compartment. A separate feature, AdipoQuant, fragments adipocyte ghosts in H&E-stained sections of extramedullary adipose tissue to render adipocyte area and size distribution. Quantification of BM hematopoietic cellularity with MarrowQuant lies within the range of scoring by four independent pathologists, while quantification of the total adipocyte area in whole bone sections compares with volumetric measurements. Employing our tool, we were able to develop a standardized map of BM hematopoietic cellularity and adiposity in mid-sections of murine C57BL/6 bones in homeostatic conditions, including quantification of the highly predictable red-to-yellow transitions in the proximal section of the caudal tail and in the proximal-to-distal tibia. Additionally, we present a comparative skeletal map induced by lethal irradiation, with longitudinal quantification of the "red-to-yellow-to-red" transition over 2 months in C57BL/6 femurs and tibiae. We find that, following BM transplantation, BM adiposity inversely correlates with kinetics of hematopoietic recovery and that a proximal to distal gradient is conserved. Analysis of in vivo recovery through magnetic resonance imaging (MRI) reveals comparable kinetics. On human trephine biopsies MarrowQuant successfully recognizes the BM compartments, opening avenues for its application in experimental, or clinical contexts that require standardized human BM evaluation.
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Affiliation(s)
- Josefine Tratwal
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - David Bekri
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Chiheb Boussema
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Rita Sarkis
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Nicolas Kunz
- Animal Imaging and Technology Core, Center for Biomedical Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Tereza Koliqi
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Shanti Rojas-Sutterlin
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Frédérica Schyrr
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Daniel Naveed Tavakol
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Vasco Campos
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Erica L. Scheller
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University, Saint Louis, MO, United States
| | - Rossella Sarro
- Institute of Pathology, Lausanne University Hospital (CHUV), Lausanne University (UNIL), Lausanne, Switzerland
| | - Carmen Bárcena
- Department of Pathology, University Hospital 12 de Octubre, Madrid, Spain
| | - Bettina Bisig
- Institute of Pathology, Lausanne University Hospital (CHUV), Lausanne University (UNIL), Lausanne, Switzerland
| | - Valentina Nardi
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Laurence de Leval
- Institute of Pathology, Lausanne University Hospital (CHUV), Lausanne University (UNIL), Lausanne, Switzerland
| | - Olivier Burri
- Bioimaging and Optics Core Facility, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Olaia Naveiras
- Laboratory of Regenerative Hematopoiesis, Institute of Bioengineering and Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Department of Oncology, Hematology Service, Lausanne University Hospital (CHUV), Lausanne, Switzerland
- *Correspondence: Olaia Naveiras ;
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Sa de Almeida J, Lordier L, Zollinger B, Kunz N, Bastiani M, Gui L, Adam-Darque A, Borradori-Tolsa C, Lazeyras F, Hüppi PS. Music enhances structural maturation of emotional processing neural pathways in very preterm infants. Neuroimage 2019; 207:116391. [PMID: 31765804 DOI: 10.1016/j.neuroimage.2019.116391] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 11/18/2019] [Accepted: 11/21/2019] [Indexed: 11/26/2022] Open
Abstract
Prematurity disrupts brain maturation by exposing the developing brain to different noxious stimuli present in the neonatal intensive care unit (NICU) and depriving it from meaningful sensory inputs during a critical period of brain development, leading to later neurodevelopmental impairments. Musicotherapy in the NICU environment has been proposed to promote sensory stimulation, relevant for activity-dependent brain plasticity, but its impact on brain structural maturation is unknown. Neuroimaging studies have demonstrated that music listening triggers neural substrates implied in socio-emotional processing and, thus, it might influence networks formed early in development and known to be affected by prematurity. Using multi-modal MRI, we aimed to evaluate the impact of a specially composed music intervention during NICU stay on preterm infant's brain structure maturation. 30 preterm newborns (out of which 15 were exposed to music during NICU stay and 15 without music intervention) and 15 full-term newborns underwent an MRI examination at term-equivalent age, comprising diffusion tensor imaging (DTI), used to evaluate white matter maturation using both region-of-interest and seed-based tractography approaches, as well as a T2-weighted image, used to perform amygdala volumetric analysis. Overall, WM microstructural maturity measured through DTI metrics was reduced in preterm infants receiving the standard-of-care in comparison to full-term newborns, whereas preterm infants exposed to the music intervention demonstrated significantly improved white matter maturation in acoustic radiations, external capsule/claustrum/extreme capsule and uncinate fasciculus, as well as larger amygdala volumes, in comparison to preterm infants with standard-of-care. These results suggest a structural maturational effect of the proposed music intervention on premature infants' auditory and emotional processing neural pathways during a key period of brain development.
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Affiliation(s)
- Joana Sa de Almeida
- Division of Development and Growth, Department of Woman, Child and Adolescent, University Hospitals of Geneva, Geneva, Switzerland
| | - Lara Lordier
- Division of Development and Growth, Department of Woman, Child and Adolescent, University Hospitals of Geneva, Geneva, Switzerland
| | | | - Nicolas Kunz
- Center of BioMedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Matteo Bastiani
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, UK; NIHR Biomedical Research Centre, University of Nottingham, UK; Wellcome Centre for Integrative Neuroimaging (WIN) - Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB), University of Oxford, UK
| | - Laura Gui
- Department of Radiology and Medical Informatics, Center of BioMedical Imaging (CIBM), University of Geneva, Geneva, Switzerland
| | - Alexandra Adam-Darque
- Division of Development and Growth, Department of Woman, Child and Adolescent, University Hospitals of Geneva, Geneva, Switzerland
| | - Cristina Borradori-Tolsa
- Division of Development and Growth, Department of Woman, Child and Adolescent, University Hospitals of Geneva, Geneva, Switzerland
| | - François Lazeyras
- Department of Radiology and Medical Informatics, Center of BioMedical Imaging (CIBM), University of Geneva, Geneva, Switzerland
| | - Petra S Hüppi
- Division of Development and Growth, Department of Woman, Child and Adolescent, University Hospitals of Geneva, Geneva, Switzerland.
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Kunz N, da Silva AR, Jelescu IO. Intra- and extra-axonal axial diffusivities in the white matter: Which one is faster? Neuroimage 2018; 181:314-322. [PMID: 30005917 DOI: 10.1016/j.neuroimage.2018.07.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 06/29/2018] [Accepted: 07/09/2018] [Indexed: 10/28/2022] Open
Abstract
A two-compartment model of diffusion in white matter, which accounts for intra- and extra-axonal spaces, is associated with two plausible mathematical scenarios: either the intra-axonal axial diffusivity Da,‖ is higher than the extra-axonal De,‖ (Branch 1), or the opposite, i.e. Da,‖ < De,‖ (Branch 2). This duality calls for an independent validation of compartment axial diffusivities, to determine which of the two cases holds. The aim of the present study was to use an intracerebroventricular injection of a gadolinium-based contrast agent to selectively reduce the extracellular water signal in the rat brain, and compare diffusion metrics in the genu of the corpus callosum before and after gadolinium infusion. The diffusion metrics considered were diffusion and kurtosis tensor metrics, as well as compartment-specific estimates of the WMTI-Watson two-compartment model. A strong decrease in genu T1 and T2 relaxation times post-Gd was observed (p < 0.001), as well as an increase of 48% in radial kurtosis (p < 0.05), which implies that the relative fraction of extracellular water signal was selectively decreased. This was further supported by a significant increase in intra-axonal water fraction as estimated from the two-compartment model, for both branches (p < 0.01 for Branch 1, p < 0.05 for Branch 2). However, pre-Gd estimates of axon dispersion in Branch 1 agreed better with literature than those of Branch 2. Furthermore, comparison of post-Gd changes in diffusivity and dispersion between data and simulations further supported Branch 1 as the biologically plausible solution, i.e. Da,‖ > De,‖. This result is fully consistent with other recent measurements of compartment axial diffusivities that used entirely different approaches, such as diffusion tensor encoding.
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Affiliation(s)
- Nicolas Kunz
- Centre d'Imagerie Biomédicale, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Analina R da Silva
- Centre d'Imagerie Biomédicale, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Ileana O Jelescu
- Centre d'Imagerie Biomédicale, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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Dehghani M, Kunz N, Lanz B, Yoshihara HAI, Gruetter R. Diffusion-weighted MRS of acetate in the rat brain. NMR Biomed 2017; 30:e3768. [PMID: 28796319 DOI: 10.1002/nbm.3768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 05/04/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
Acetate has been proposed as an astrocyte-specific energy substrate for metabolic studies in the brain. The determination of the relative contribution of the intracellular and extracellular compartments to the acetate signal using diffusion-weighted magnetic resonance spectroscopy can provide an insight into the cellular environment and distribution volume of acetate in the brain. In the present study, localized 1 H nuclear magnetic resonance (NMR) spectroscopy employing a diffusion-weighted stimulated echo acquisition mode (STEAM) sequence at an ultra-high magnetic field (14.1 T) was used to investigate the diffusivity characteristics of acetate and N-acetylaspartate (NAA) in the rat brain in vivo during prolonged acetate infusion. The persistence of the acetate resonance in 1 H spectra acquired at very large diffusion weighting indicated restricted diffusion of acetate and was attributed to intracellular spaces. However, the significantly greater diffusion of acetate relative to NAA suggests that a substantial fraction of acetate is located in the extracellular space of the brain. Assuming an even distribution for acetate in intracellular and extracellular spaces, the diffusion properties of acetate yielded a smaller volume of distribution for acetate relative to water and glucose in the rat brain.
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Affiliation(s)
- Masoumeh Dehghani
- Laboratoire d'imagerie fonctionnelle et métabolique (LIFMET), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Nicolas Kunz
- Centre d'Imagerie BioMédicale (CIBM)-AIT, École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Bernard Lanz
- Laboratoire d'imagerie fonctionnelle et métabolique (LIFMET), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Hikari A I Yoshihara
- Service de Cardiologie, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratoire d'imagerie fonctionnelle et métabolique (LIFMET), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Centre d'Imagerie BioMédicale (CIBM), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Department of Radiology, Université de Lausanne (UNIL), Lausanne, Switzerland
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Lander M, Kunz N, Dunn E, Lockard K, O’Shea G, Weaver S, Schweke T, Shullo M, Lagazzi L, Kormos R, Teuteberg J. Substantial Reduction in Driveline Infection Rates with the Modification of Driveline Dressing Protocols. J Heart Lung Transplant 2016. [DOI: 10.1016/j.healun.2016.01.462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Dehghani M M, Lanz B, Duarte JMN, Kunz N, Gruetter R. Refined Analysis of Brain Energy Metabolism Using In Vivo Dynamic Enrichment of 13C Multiplets. ASN Neuro 2016; 8:8/2/1759091416632342. [PMID: 26969691 PMCID: PMC4790427 DOI: 10.1177/1759091416632342] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 12/30/2015] [Indexed: 11/18/2022] Open
Abstract
Carbon-13 nuclear magnetic resonance spectroscopy in combination with the infusion of 13C-labeled precursors is a unique approach to study in vivo brain energy metabolism. Incorporating the maximum information available from in vivo localized 13C spectra is of importance to get broader knowledge on cerebral metabolic pathways. Metabolic rates can be quantitatively determined from the rate of 13C incorporation into amino acid neurotransmitters such as glutamate and glutamine using suitable mathematical models. The time course of multiplets arising from 13C-13C coupling between adjacent carbon atoms was expected to provide additional information for metabolic modeling leading to potential improvements in the estimation of metabolic parameters. The aim of the present study was to extend two-compartment neuronal/glial modeling to include dynamics of 13C isotopomers available from fine structure multiplets in 13C spectra of glutamate and glutamine measured in vivo in rats brain at 14.1 T, termed bonded cumomer approach. Incorporating the labeling time courses of 13C multiplets of glutamate and glutamine resulted in elevated precision of the estimated fluxes in rat brain as well as reduced correlations between them.
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Affiliation(s)
- Masoumeh Dehghani M
- Laboratory for Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Bernard Lanz
- Laboratory for Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - João M N Duarte
- Laboratory for Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland Department of Radiology, University of Lausanne, Switzerland
| | - Nicolas Kunz
- CIBM-AIT, Ecole Polytechnique Fédérale de Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland Department of Radiology, University of Lausanne, Switzerland Department of Radiology, University of Geneva, Switzerland
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Schmidt R, Mishkovsky M, Hyacinthe JN, Kunz N, Gruetter R, Comment A, Frydman L. Correcting surface coil excitation inhomogeneities in single-shot SPEN MRI. J Magn Reson 2015; 259:199-206. [PMID: 26363583 PMCID: PMC5035682 DOI: 10.1016/j.jmr.2015.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 05/08/2023]
Abstract
Given their high sensitivity and ability to limit the field of view (FOV), surface coils are often used in magnetic resonance spectroscopy (MRS) and imaging (MRI). A major downside of surface coils is their inherent radiofrequency (RF) B1 heterogeneity across the FOV, decreasing with increasing distance from the coil and giving rise to image distortions due to non-uniform spatial responses. A robust way to compensate for B1 inhomogeneities is to employ adiabatic inversion pulses, yet these are not well adapted to all imaging sequences - including to single-shot approaches like echo planar imaging (EPI). Hybrid spatiotemporal encoding (SPEN) sequences relying on frequency-swept pulses provide another ultrafast MRI alternative, that could help solve this problem thanks to their built-in heterogeneous spatial manipulations. This study explores how this intrinsic SPEN-based spatial discrimination, could be used to compensate for the B1 inhomogeneities inherent to surface coils. Experiments carried out in both phantoms and in vivo rat brains demonstrate that, by suitably modulating the amplitude of a SPEN chirp pulse that progressively excites the spins in a direction normal to the coil, it is possible to compensate for the RF transmit inhomogeneities and thus improve sensitivity and image fidelity.
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Affiliation(s)
- Rita Schmidt
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Mor Mishkovsky
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Jean-Noel Hyacinthe
- School of health, University of Applied Sciences and Arts Western Switzerland, Geneva, Switzerland
| | - Nicolas Kunz
- Center of Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Center of Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Arnaud Comment
- Institute of the Physics of Biological Systems, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Lucio Frydman
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
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Lemkaddem A, Daducci A, Kunz N, Lazeyras F, Seeck M, Thiran JP, Vulliémoz S. Connectivity and tissue microstructural alterations in right and left temporal lobe epilepsy revealed by diffusion spectrum imaging. Neuroimage Clin 2014; 5:349-58. [PMID: 26236626 PMCID: PMC4519999 DOI: 10.1016/j.nicl.2014.07.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 07/15/2014] [Accepted: 07/29/2014] [Indexed: 10/27/2022]
Abstract
Focal epilepsy is increasingly recognized as the result of an altered brain network, both on the structural and functional levels and the characterization of these widespread brain alterations is crucial for our understanding of the clinical manifestation of seizure and cognitive deficits as well as for the management of candidates to epilepsy surgery. Tractography based on Diffusion Tensor Imaging allows non-invasive mapping of white matter tracts in vivo. Recently, diffusion spectrum imaging (DSI), based on an increased number of diffusion directions and intensities, has improved the sensitivity of tractography, notably with respect to the problem of fiber crossing and recent developments allow acquisition times compatible with clinical application. We used DSI and parcellation of the gray matter in regions of interest to build whole-brain connectivity matrices describing the mutual connections between cortical and subcortical regions in patients with focal epilepsy and healthy controls. In addition, the high angular and radial resolution of DSI allowed us to evaluate also some of the biophysical compartment models, to better understand the cause of the changes in diffusion anisotropy. Global connectivity, hub architecture and regional connectivity patterns were altered in TLE patients and showed different characteristics in RTLE vs LTLE with stronger abnormalities in RTLE. The microstructural analysis suggested that disturbed axonal density contributed more than fiber orientation to the connectivity changes affecting the temporal lobes whereas fiber orientation changes were more involved in extratemporal lobe changes. Our study provides further structural evidence that RTLE and LTLE are not symmetrical entities and DSI-based imaging could help investigate the microstructural correlate of these imaging abnormalities.
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Affiliation(s)
- Alia Lemkaddem
- Ecole Polythechnique Fédéral de Lausanne, Signal Processing Laboratories (LTS5), Lausanne, Switzerland
| | - Alessandro Daducci
- Ecole Polythechnique Fédéral de Lausanne, Signal Processing Laboratories (LTS5), Lausanne, Switzerland ; Dpt of Radiology, University Hospital and University of Lausanne, Switzerland
| | - Nicolas Kunz
- Centre d'Imagerie BioMédicale (CIBM-AIT), Ecole Polythechnique Fédéral de Lausanne, Lausanne, Switzerland
| | | | - Margitta Seeck
- Epilepsy Unit, Neurology Clinic, University Hospitals and Faculty of Medicine of Geneva, Switzerland
| | - Jean-Philippe Thiran
- Ecole Polythechnique Fédéral de Lausanne, Signal Processing Laboratories (LTS5), Lausanne, Switzerland ; Dpt of Radiology, University Hospital and University of Lausanne, Switzerland
| | - Serge Vulliémoz
- Epilepsy Unit, Neurology Clinic, University Hospitals and Faculty of Medicine of Geneva, Switzerland
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Teuteberg J, McNulty M, Holtz J, Kunz N, Lockard K, Dunn E, Bermudez C, Bhama J, Shullo M, Kormos R, Dew M. Impact of Mechanical Support on Quality of Life Measures Over Time - Is There a Differential Response Based Upon Indication? J Heart Lung Transplant 2014. [DOI: 10.1016/j.healun.2014.01.589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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14
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Kunz N, Sizonenko SV, Hüppi PS, Gruetter R, van de Looij Y. Investigation of field and diffusion time dependence of the diffusion-weighted signal at ultrahigh magnetic fields. NMR Biomed 2013; 26:1251-1257. [PMID: 23533088 DOI: 10.1002/nbm.2945] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 02/01/2013] [Accepted: 02/18/2013] [Indexed: 06/02/2023]
Abstract
Over the last decade, there has been a significant increase in the number of high-magnetic-field MRI magnets. However, the exact effect of a high magnetic field strength (B0 ) on diffusion-weighted MR signals is not yet fully understood. The goal of this study was to investigate the influence of different high magnetic field strengths (9.4 T and 14.1 T) and diffusion times (9, 11, 13, 15, 17 and 24 ms) on the diffusion-weighted signal in rat brain white matter. At a short diffusion time (9 ms), fractional anisotropy values were found to be lower at 14.1 T than at 9.4 T, but this difference disappeared at longer diffusion times. A simple two-pool model was used to explain these findings. The model describes the white matter as a first hindered compartment (often associated with the extra-axonal space), characterized by a faster orthogonal diffusion and a lower fractional anisotropy, and a second restricted compartment (often associated with the intra-axonal space), characterized by a slower orthogonal diffusion (i.e. orthogonal to the axon direction) and a higher fractional anisotropy. Apparent T2 relaxation time measurements of the hindered and restricted pools were performed. The shortening of the pseudo-T2 value from the restricted compartment with B0 is likely to be more pronounced than the apparent T2 changes in the hindered compartment. This study suggests that the observed differences in diffusion tensor imaging parameters between the two magnetic field strengths at short diffusion time may be related to differences in the apparent T2 values between the pools.
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Affiliation(s)
- Nicolas Kunz
- Division of Child Growth and Development, University of Geneva, Geneva, Switzerland; Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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15
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Assaf Y, Alexander DC, Jones DK, Bizzi A, Behrens TEJ, Clark CA, Cohen Y, Dyrby TB, Huppi PS, Knoesche TR, Lebihan D, Parker GJM, Poupon C, Anaby D, Anwander A, Bar L, Barazany D, Blumenfeld-Katzir T, De-Santis S, Duclap D, Figini M, Fischi E, Guevara P, Hubbard P, Hofstetter S, Jbabdi S, Kunz N, Lazeyras F, Lebois A, Liptrot MG, Lundell H, Mangin JF, Dominguez DM, Morozov D, Schreiber J, Seunarine K, Nava S, Poupon C, Riffert T, Sasson E, Schmitt B, Shemesh N, Sotiropoulos SN, Tavor I, Zhang HG, Zhou FL. The CONNECT project: Combining macro- and micro-structure. Neuroimage 2013; 80:273-82. [PMID: 23727318 DOI: 10.1016/j.neuroimage.2013.05.055] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 05/06/2013] [Accepted: 05/08/2013] [Indexed: 11/28/2022] Open
Abstract
In recent years, diffusion MRI has become an extremely important tool for studying the morphology of living brain tissue, as it provides unique insights into both its macrostructure and microstructure. Recent applications of diffusion MRI aimed to characterize the structural connectome using tractography to infer connectivity between brain regions. In parallel to the development of tractography, additional diffusion MRI based frameworks (CHARMED, AxCaliber, ActiveAx) were developed enabling the extraction of a multitude of micro-structural parameters (axon diameter distribution, mean axonal diameter and axonal density). This unique insight into both tissue microstructure and connectivity has enormous potential value in understanding the structure and organization of the brain as well as providing unique insights to abnormalities that underpin disease states. The CONNECT (Consortium Of Neuroimagers for the Non-invasive Exploration of brain Connectivity and Tracts) project aimed to combine tractography and micro-structural measures of the living human brain in order to obtain a better estimate of the connectome, while also striving to extend validation of these measurements. This paper summarizes the project and describes the perspective of using micro-structural measures to study the connectome.
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Affiliation(s)
- Yaniv Assaf
- Department of Neurobiology, George S. Wise Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel.
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Teuteberg J, Kormos R, Lockard K, Kunz N, Allen C, Scanlon A, Weaver S, Hall D, Bermudez C, Shullo M. Management of Anticoagulation in Patients with Mechanical Circulatory Support Using a Physician-Based Versus a Pharmacist Directed Anticoagulation Clinic-Based Strategy. J Heart Lung Transplant 2013. [DOI: 10.1016/j.healun.2013.01.782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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17
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Lampert B, Shullo M, Kunz N, Lockard K, Allen C, Bhama J, Bermudez C, Kormos R, Teuteberg J. Effect of Blood Pressure (BP) Control in Continuous Flow Left Ventricular Assist Devices (CF-LVAD) on Aortic Insufficiency (AI) and Neurologic Events. J Heart Lung Transplant 2013. [DOI: 10.1016/j.healun.2013.01.878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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18
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Schaller B, Mekle R, Xin L, Kunz N, Gruetter R. Net increase of lactate and glutamate concentration in activated human visual cortex detected with magnetic resonance spectroscopy at 7 tesla. J Neurosci Res 2013; 91:1076-83. [PMID: 23378234 DOI: 10.1002/jnr.23194] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 11/21/2012] [Indexed: 11/08/2022]
Abstract
After the landmark studies reporting changes in the cerebral metabolic rate of glucose (CMRGlc ) in excess of those in oxygen (CMRO2 ) during physiological stimulation, several studies have examined the fate of the extra carbon taken up by the brain, reporting a wide range of changes in brain lactate from 20% to 250%. The present study reports functional magnetic resonance spectroscopy measurements at 7 Tesla using the enhanced sensitivity to study a small cohort (n = 6). Small increases in lactate (19% ± 4%, P < 0.05) and glutamate (4% ± 1%, P < 0.001) were seen within the first 2 min of activation. With the exception of glucose (12% ± 5%, P < 0.001), no other metabolite concentration changes beyond experimental error were significantly observed. Therefore, the present study confirms that lactate and glutamate changes during physiological stimulation are small (i.e. below 20%) and shows that the increased sensitivity allows reproduction of previous results with fewer subjects. In addition, the initial rate of glutamate and lactate concentration increases implies an increase in CMRO2 that is slightly below that of CMRGlc during the first 1-2 min of activation.
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Affiliation(s)
- Benoît Schaller
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
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Lanz B, Duarte JMN, Kunz N, Mlynárik V, Gruetter R, Cudalbu C. Which prior knowledge? Quantification of in vivo brain 13C MR spectra following 13C glucose infusion using AMARES. Magn Reson Med 2012; 69:1512-22. [PMID: 22886985 DOI: 10.1002/mrm.24406] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/30/2012] [Accepted: 06/13/2012] [Indexed: 11/06/2022]
Abstract
The recent developments in high magnetic field 13C magnetic resonance spectroscopy with improved localization and shimming techniques have led to important gains in sensitivity and spectral resolution of 13C in vivo spectra in the rodent brain, enabling the separation of several 13C isotopomers of glutamate and glutamine. In this context, the assumptions used in spectral quantification might have a significant impact on the determination of the 13C concentrations and the related metabolic fluxes. In this study, the time domain spectral quantification algorithm AMARES (advanced method for accurate, robust and efficient spectral fitting) was applied to 13 C magnetic resonance spectroscopy spectra acquired in the rat brain at 9.4 T, following infusion of [1,6-(13)C2 ] glucose. Using both Monte Carlo simulations and in vivo data, the goal of this work was: (1) to validate the quantification of in vivo 13C isotopomers using AMARES; (2) to assess the impact of the prior knowledge on the quantification of in vivo 13C isotopomers using AMARES; (3) to compare AMARES and LCModel (linear combination of model spectra) for the quantification of in vivo 13C spectra. AMARES led to accurate and reliable 13C spectral quantification similar to those obtained using LCModel, when the frequency shifts, J-coupling constants and phase patterns of the different 13C isotopomers were included as prior knowledge in the analysis.
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Affiliation(s)
- Bernard Lanz
- Laboratory for Functional and Metabolic Imaging (LIFMET), Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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20
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Kunz N, Camm EJ, Somm E, Lodygensky G, Darbre S, Aubert ML, Hüppi PS, Sizonenko SV, Gruetter R. Developmental and metabolic brain alterations in rats exposed to bisphenol A during gestation and lactation. Int J Dev Neurosci 2010; 29:37-43. [PMID: 20955774 DOI: 10.1016/j.ijdevneu.2010.09.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 09/14/2010] [Accepted: 09/27/2010] [Indexed: 11/30/2022] Open
Abstract
In recent years, considerable research has focused on the biological effect of endocrine-disrupting chemicals. Bisphenol A (BPA) has been implicated as an endocrine-disrupting chemical (EDC) due to its ability to mimic the action of endogenous estrogenic hormones. The aim of this study was to assess the effect of perinatal exposure to BPA on cerebral structural development and metabolism after birth. BPA (1mg/l) was administered in the drinking water of pregnant dams from day 6 of gestation until pup weaning. At postnatal day 20, in vivo metabolite concentrations in the rat pup hippocampus were measured using high field proton magnetic resonance spectroscopy. Further, brain was assessed histologically for growth, gross morphology, glial and neuronal development and extent of myelination. Localized proton magnetic resonance spectroscopy ((1)H MRS) showed in the BPA-exposed rat a significant increase in glutamate concentration in the hippocampus as well as in the Glu/Asp ratio. Interestingly these two metabolites are metabolically linked together in the malate-aspartate metabolic shuttle. Quantitative histological analysis revealed that the density of NeuN-positive neurons in the hippocampus was decreased in the BPA-treated offspring when compared to controls. Conversely, the density of GFAP-positive astrocytes in the cingulum was increased in BPA-treated offspring. In conclusion, exposure to low-dose BPA during gestation and lactation leads to significant changes in the Glu/Asp ratio in the hippocampus, which may reflect impaired mitochondrial function and also result in neuronal and glial developmental alterations.
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Affiliation(s)
- Nicolas Kunz
- Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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van de Looij Y, Kunz N, Hüppi P, Gruetter R, Sizonenko S. Diffusion tensor echo planar imaging using surface coil transceiver with a semiadiabatic RF pulse sequence at 14.1T. Magn Reson Med 2010; 65:732-7. [PMID: 20939068 DOI: 10.1002/mrm.22656] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 08/03/2010] [Accepted: 08/29/2010] [Indexed: 11/07/2022]
Abstract
Diffusion magnetic resonance studies of the brain are typically performed using volume coils. Although in human brain this leads to a near optimal filling factor, studies of rodent brain must contend with the fact that only a fraction of the head volume can be ascribed to the brain. The use of surface coil as transceiver increases Signal-to-Noise Ratio (SNR), reduces radiofrequency power requirements and opens the possibility of parallel transmit schemes, likely to allow efficient acquisition schemes, of critical importance for reducing the long scan times implicated in diffusion tensor imaging. This study demonstrates the implementation of a semiadiabatic echo planar imaging sequence (echo time=40 ms, four interleaves) at 14.1T using a quadrature surface coil as transceiver. It resulted in artifact free images with excellent SNR throughout the brain. Diffusion tensor derived parameters obtained within the rat brain were in excellent agreement with reported values.
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Affiliation(s)
- Yohan van de Looij
- Department of Pediatrics, Division of Child Growth and Development, University of Geneva, Geneva, Switzerland
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Kunz N, Cudalbu C, Mlynarik V, Hüppi PS, Sizonenko SV, Gruetter R. Diffusion-weighted spectroscopy: A novel approach to determine macromolecule resonances in short-echo time 1H-MRS. Magn Reson Med 2010; 64:939-46. [DOI: 10.1002/mrm.22490] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bertsche T, Bertsche A, Krieg EM, Kunz N, Bergmann K, Hanke G, Hoppe-Tichy T, Ebinger F, Haefeli WE. Prospective pilot intervention study to prevent medication errors in drugs administered to children by mouth or gastric tube: a programme for nurses, physicians and parents. Qual Saf Health Care 2010; 19:e26. [PMID: 20378618 DOI: 10.1136/qshc.2009.033753] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Drug administration in children is an error-prone task for nurses and parents because individual dose adjustment is often necessary, and suitable formulations for children are frequently lacking. Hence, in the absence of measures for their prevention, medication errors are likely to occur. OBJECTIVE To assess the error prevalence in drug administration by mouth or gastric tube before and after implementing a programme for quality improvement for nurses and parents. DESIGN, SETTING AND PARTICIPANTS Prospective, two-period cohort intervention study on a paediatric neurology ward of a university hospital where drug administration procedures of nurses and parents were consecutively monitored during the routine drug administration hours. MAIN OUTCOMES MEASURE Prevalence of administration errors before and after implementing instructions for appropriate drug administration, and a teaching and training programme supported by information pamphlets. RESULTS Altogether, 1164 predefined administration tasks were assessed, 675 before and 489 after the intervention. Of these, 95.7% (after the INTERVENTION 92.6%) were performed by nurses. Errors addressed by the intervention were reduced from 261/646 tasks (40.4%) to 36/453 (7.9%, p<0.001) in nurses and from 28/29 (96.6%) to 2/36 (5.6%, p<0.001) in parents. Errors in predefined categories concerning tablet dissolution, tablet storage, oral liquids, tablet splitting, administration by gastric tube and others were all considerably less frequent after the intervention (each p<0.001). CONCLUSION Errors of drug administration by mouth and gastric tube represent a considerable and often neglected drug-related problem in paediatric inpatients. Targeted quality-improvement programmes can substantially and rapidly reduce error prevalence. Appropriate teaching and training of both nurses and parents supported by pamphlets was a highly efficient way to reduce error prevalence.
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Affiliation(s)
- T Bertsche
- Department of Clinical Pharmacology and Pharmacoepidemiology, INF 410, 69120 Heidelberg, Germany
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Esselmann H, Maler JM, Kunz N, Otto M, Paul S, Lewczuk P, Rüther E, Kornhuber J, Wiltfang J. Lithium decreases secretion of Abeta1-42 and C-truncated species Abeta1-37/38/39/40 in chicken telencephalic cultures but specifically increases intracellular Abeta1-38. NEURODEGENER DIS 2006; 1:236-41. [PMID: 16908996 DOI: 10.1159/000080992] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We studied endogenous amyloid precursor protein (APP) processing and amyloid beta (Abeta) peptide formation in primary chicken telencephalic neurons, because their Abeta peptide sequence is identical to humans. As detected by quantitative Abeta-SDS-PAGE/immunoblot, Abeta peptides 1-40/42 and three additional C-truncated species, namely Abeta1-37/38/39 were regularly released into the supernatant. The highly conserved Abeta quintet strongly resembles the pattern of Abeta peptides found in human cerebrospinal fluid. Furthermore, the C-terminally shorter Abeta peptides 1-33/34 could be readily detected. Recent evidence indicates that lithium specifically inhibits secretion of the amyloidogenic Abeta1-42 peptide in cultured permanent cells transfected with human APP. We therefore investigated the effect of lithium on Abeta peptide secretion as well as intracellular Abeta peptides in our untransfected primary cell culture system. Our data shows that lithium leads to a dose-dependent reduction of Abeta1-37/38/39/40/42 secretion. Surprisingly, intracellular analysis revealed that lithium specifically increases a band comigrating with synthetic Abeta1-38 while Abeta1-40 and Abeta1-42 remained almost unaffected. These results demonstrate for the first time that lithium treatment decreases Abeta peptide secretion in primary chicken neuronal cells but specifically elevates intracellular Abeta1-38. Therefore, we conclude that there are two independent mechanisms of lithium in intra- and extracellular Abeta peptide production.
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Affiliation(s)
- H Esselmann
- Department of Psychiatry, University of Göttingen, Göttingen, Germany
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Abstract
Compounds active at the serotonin (5-HT)1A receptor (mostly azapirones) have shown some evidence of antidepressant effect. We report here the results of an antidepressant trial with zalospirone, a novel cyclic imide with 5-HT1A partial agonist activity. Two hundred eighty-seven outpatients (mean age 44 years, 55% men, 45% nonfertile women) who met criteria for unipolar major depression with a minimum 21-item Hamilton Rating Scale for Depression (HAM-D) score of 20 were randomly assigned to receive 6 weeks of double-blind treatment with either placebo or one of three fixed doses of zalospirone (6, 15, or 45 mg/day), administered three times daily. The high dose (45 mg) of zalospirone produced a significant antidepressant effect compared with placebo from week 2 on with mean improvement (change from baseline) in HAM-D total score of 12.8 versus 8.4 (p < 0.05) at week 6. Clinical improvement with the high dose of zalospirone was consistent across all outcome measures, however, only in the observed cases and not the last-observation-carried-forward analyses. Improvement with the 6-mg or 15-mg doses was greater than that with placebo, but not significantly so, suggesting a dose-response effect. Although the 45-mg dose of zalospirone seemed to have significant antidepressant efficacy, it was not well tolerated. Dizziness and nausea were noted in almost half of the patients, and by week six, 51% of patients in the high-dose group had dropped out. Whether or not tolerance to this high dose might be improved by gradual drug titration, only future research can answer.
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Affiliation(s)
- K Rickels
- Department of Psychiatry, University of Pennsylvania, Philadelphia
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Seifert J, Kunz N, Flachmann R, Läufer A, Jany KD, Gassen HG. Expression of the E. coli nadB gene and characterization of the gene product L-aspartate oxidase. Biol Chem Hoppe Seyler 1990; 371:239-48. [PMID: 2187483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Quinolinic acid is synthesized in E. coli by the enzymes L-aspartate oxidase and quinolinate synthase A, the genes of which are named nadB and nadA. In our previous work we cloned and characterized the two genes (Flachmann, R., Kunz, N., Seifert, J., Gütlich, M., Wientjes, F.J., Läufer, A. & Gassen, H.G. (1988) Eur. J. Biochem. 175, 221-228). Here we report on the expression of the nadB gene under control of the inducible left promoter of the bacteriophage lambda. The yield of the active gene product L-aspartate oxidase was enhanced up to 20% of the soluble cell protein. The enzyme was purified to homogeneity in a three-step procedure and the reading frame of the L-aspartate oxidase gene was confirmed by Edman degradation of five cyanogen bromide peptides. L-Aspartate oxidase shows no classical Michaelis-Menten behaviour but is subject to a substrate inactivation. The apparent Km values were different for substrate concentrations below and above 1mM and were determined to 0.5 mM and 4.1mM, respectively. The active form of the enzyme is a monomer of 60,284 Da and contains one molecule of FAD and nine cysteine residues, four of which built up two disulfide bonds. The isoelectric point of the protein was determined to be at pH 5.6. Chemical modifications of the enzyme showed that at least one tyrosine and one histidine residue are essential for enzyme activity. The coenzyme-binding domain is located in the amino-terminal part of the polypeptide chain as revealed by a sequence comparison to other dinucleotide binding enzymes. Furthermore, there is evidence for a relationship to fumarate reductase and succinate dehydrogenase of E. coli.
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Affiliation(s)
- J Seifert
- Institut für Biochemie, Technische Hochschule Darmstadt
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Flachmann R, Kunz N, Seifert J, Gütlich M, Wientjes FJ, Läufer A, Gassen HG. Molecular biology of pyridine nucleotide biosynthesis in Escherichia coli. Cloning and characterization of quinolinate synthesis genes nadA and nadB. Eur J Biochem 1988; 175:221-8. [PMID: 2841129 DOI: 10.1111/j.1432-1033.1988.tb14187.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The two genes, nadA and nadB, responsible for quinolinate biosynthesis from aspartate and dihydroxyacetone phosphate in Escherichia coli were cloned and characterized. Quinolinate (pyridine-2,3-dicarboxylate) is the biosynthetic precursor of the pyridine ring of NAD. Gene nadA was identified by complementation in three different nadA mutant strains. Sequence analysis provided an 840-bp open reading frame coding for a 31,555-Da protein. Gene nadB was identified by complementation in a nadB mutant strain and by the L-aspartate oxidase activity of its gene product. Sequence analysis showed a 1620-bp open reading frame coding for a 60,306-Da protein. For both genes, promoter regions and ribosomal binding sites were assigned by comparison to consensus sequences. The nadB gene product, L-aspartate oxidase, was purified to homogeneity and the N-terminal sequence of 19 amino acids was determined. The enzyme was shown to be specific for L-aspartate. High-copy-number vectors, carrying either gene nadA, nadB or nadA + nadB, increased quinolinate production 1.5-fold, 2.0-fold and 15-fold respectively. Both gene products seem to be equally rate-limiting in quinolinate synthesis.
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Affiliation(s)
- R Flachmann
- Institut für Biochemie, Technische Hochschule Darmstadt, Federal Republic of Germany
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Höck A, Schürch P, Freundlieb C, Vyska K, Kunz N, Feinendegen LE, Hollmann W. [Global and regional changes of cardiopulmonary blood volume under continuous work load (author's transl)]. Nuklearmedizin 1980; 19:166-73. [PMID: 7208360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The present study describes a method for the continuous determination of global and regional stress-induced alterations of cardiopulmonary blood volumes in normals, trained athletes and patients with latent cardiac insufficiency. In contrast to normals and athletes there is an increase of the total cardiac blood volume in the cardiac patients. There are also significant differences in blood volume changes of the left lung between normals and athletes on the one hand and the cardiac patients on the other. The method is simple and non-hazardous; it permits the observation of the obviously different adaptation of the cardiopulmonary system during exercise in normals, athletes and cardiac patients.
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Freundlieb C, Vyska K, Feinendegen LE, Höck A, Schürch P, Kunz N, Hollmann W. Globale und regionale kardiopulmonale Blutvolumen-Änderungen unter kontinuierlicher Belastung. Nuklearmedizin 1980. [DOI: 10.1055/s-0037-1620945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
ZusammenfassungDie vorliegende Arbeit beschreibt eine Methode zur kontinuierlichen Registrierung globaler und regionaler belastungsinduzierter Änderungen des kardialen und pulmonalen Blutvolumens bei Normalpersonen, Sportlern und latent herzinsuffizienten Patienten. Im Gegensatz zu Normalpersonen und Sportlern steigt das Blutvolumen des Gesamtherzens im Verlauf einer Belastung bei Patienten mit latenter Herzinsuffizienz an. Ebenso signifikant sind die unterschiedlichen BlutvolumenÄnderungen über der linken Lunge bei Normalpersonen und Sportlern einerseits und latent herzinsuffizienten Patienten andererseits. Die Methode ist einfach und sicher; sie erlaubt, die bei gesunden Sportlern und herzkranken Patienten offensichtlich unterschiedliche Adaptation des kardiopulmonalen Systems wÄhrend körperlicher Belastung fortlaufend zu erfassen.
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