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Donjuán-Loredo G, Espinosa-Tanguma R, León-Bejarano F, Ramírez-Elías JA, Salgado-Delgado R, González FJ, Guevara E, Ramírez-Elías MG. Raman Spectroscopy for Adipose Tissue Assessment in Rat Models of Obesity and Type 1 Diabetes. APPLIED SPECTROSCOPY 2021; 75:1189-1197. [PMID: 33464156 DOI: 10.1177/0003702821990357] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Adipose tissue presents structural and functional changes in obesity and type 1 diabetes mellitus (T1DM). In obesity, the size and number of adipocytes and adipokine secretion increases. In T1DM, a loss of adipose tissue suggests changes in the metabolic activity of this tissue. A significant challenge is to find alternative noninvasive methods to evaluate molecular changes in adipose tissue related to obesity and T1DM. Recently, Raman spectroscopy and chemometrics techniques have emerged as a tool for biological tissue analysis. In this work, we propose the use of Raman spectroscopy to characterize spectral differences in adipose tissue from different rat groups (control, obese, and T1DM). The Raman spectra were analyzed using direct band analysis, ratiometric analysis, and chemometric methods (principal component analysis (PCA) and support vector machines (SVMs)). We found that the Raman spectra of obese rats showed significant spectral differences compared to control and diabetic groups related to fatty acids Raman bands. Also, the obese group has a significant decrease in the degree of unsaturation of lipids. The PCA-SVM models showed classification performance ranging from 71.43% to 71.79% accuracy for brown and white adipose tissue samples, respectively. In conclusion, the results demonstrate that Raman spectroscopy can be used as a nondestructive method to assess adipose tissue according to a metabolic condition.
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Affiliation(s)
| | | | - Fabiola León-Bejarano
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Jordi A Ramírez-Elías
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | | | - Francisco J González
- Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología (CIACyT), Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Edgar Guevara
- Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología (CIACyT), Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
- CONACYT-Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
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2
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Minamikawa T, Ichimura-Shimizu M, Takanari H, Morimoto Y, Shiomi R, Tanioka H, Hase E, Yasui T, Tsuneyama K. Molecular imaging analysis of microvesicular and macrovesicular lipid droplets in non-alcoholic fatty liver disease by Raman microscopy. Sci Rep 2020; 10:18548. [PMID: 33122711 PMCID: PMC7596489 DOI: 10.1038/s41598-020-75604-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/16/2020] [Indexed: 12/12/2022] Open
Abstract
Predominant evidence of non-alcoholic fatty liver disease (NAFLD) is the accumulation of excess lipids in the liver. A small group with NAFLD may have a more serious condition named non-alcoholic steatohepatitis (NASH). However, there is a lack of investigation of the accumulated lipids with spatial and molecular information. Raman microscopy has the potential to characterise molecular species and structures of lipids based on molecular vibration and can achieve high spatial resolution at the organelle level. In this study, we aim to demonstrate the feasibility of Raman microscopy for the investigation of NAFLD based on the molecular features of accumulated lipids. By applying the Raman microscopy to the liver of the NASH model mice, we succeeded in visualising the distribution of lipid droplets (LDs) in hepatocytes. The detailed analysis of Raman spectra revealed the difference of molecular structural features of the LDs, such as the degree of saturation of lipids in the LDs. We also found that the inhomogeneous distribution of cholesterol in the LDs depending on the histology of lipid accumulation. We visualised and characterised the lipids of NASH model mice by Raman microscopy at organelle level. Our findings demonstrated that the Raman imaging analysis was feasible to characterise the NAFLD in terms of the molecular species and structures of lipids.
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Affiliation(s)
- Takeo Minamikawa
- Department of Post-LED Photonics Research, Institute of Post-LED Photonics, Tokushima University, 2-1 Minami-Josanjima, Tokushima, 770-8506, Japan. .,Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan. .,PRESTO, Japan Science and Technology Agency (JST), 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan. .,Research Cluster On "Multi-Scale Vibrational Microscopy for Comprehensive Diagnosis and Treatment of Cancer", Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan.
| | - Mayuko Ichimura-Shimizu
- Research Cluster On "Multi-Scale Vibrational Microscopy for Comprehensive Diagnosis and Treatment of Cancer", Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan.,Department of Pathology and Laboratory Medicine, Graduate School of Medical Sciences, Tokushima University, 3-18-15 Kuramoto, Tokushima, Tokushima, 770-8503, Japan
| | - Hiroki Takanari
- Research Cluster On "Multi-Scale Vibrational Microscopy for Comprehensive Diagnosis and Treatment of Cancer", Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan.,Department of Interdisciplinary Researches for Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, 3-18-15 Kuramoto, Tokushima, Tokushima, 770-8503, Japan
| | - Yuki Morimoto
- Research Cluster On "Multi-Scale Vibrational Microscopy for Comprehensive Diagnosis and Treatment of Cancer", Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan.,Department of Pathology and Laboratory Medicine, Graduate School of Medical Sciences, Tokushima University, 3-18-15 Kuramoto, Tokushima, Tokushima, 770-8503, Japan
| | - Ryosuke Shiomi
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan
| | - Hiroki Tanioka
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan
| | - Eiji Hase
- Department of Post-LED Photonics Research, Institute of Post-LED Photonics, Tokushima University, 2-1 Minami-Josanjima, Tokushima, 770-8506, Japan.,Research Cluster On "Multi-Scale Vibrational Microscopy for Comprehensive Diagnosis and Treatment of Cancer", Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan
| | - Takeshi Yasui
- Department of Post-LED Photonics Research, Institute of Post-LED Photonics, Tokushima University, 2-1 Minami-Josanjima, Tokushima, 770-8506, Japan.,Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan.,Research Cluster On "Multi-Scale Vibrational Microscopy for Comprehensive Diagnosis and Treatment of Cancer", Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan
| | - Koichi Tsuneyama
- Research Cluster On "Multi-Scale Vibrational Microscopy for Comprehensive Diagnosis and Treatment of Cancer", Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima, 770-8506, Japan.,Department of Pathology and Laboratory Medicine, Graduate School of Medical Sciences, Tokushima University, 3-18-15 Kuramoto, Tokushima, Tokushima, 770-8503, Japan.,Department of Interdisciplinary Researches for Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, 3-18-15 Kuramoto, Tokushima, Tokushima, 770-8503, Japan
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Abstract
Fat distribution, on top of general obesity, contributes to the severity of histologic features in patients with nonalcoholic fatty liver diseases (NAFLD); and visceral obesity has been correlated to fatty liver diseases. Therefore, investigation of fat distribution in vivo could be a good predictor of fatty liver risks in obesity. Fatty acids composition is a key player in hepatic dysfunctions and cardiovascular risk in obesity. Because fatty acids can damage biological membranes, fatty acid accumulation in the liver may be partially responsible for the functional and morphological changes that are observed in NAFLD. Fatty acids stored into triglycerides are lipid species that act as signaling molecules and therefore are key regulators of posttranslational regulation of biological functions such as lipid homeostasis and lipotoxicity. Here, we describe magnetic resonance methods to investigate in vivo whole-body fat distribution and hepatic liver fatty acid composition in order to directly assess the liver metabolic status and may allow to anticipate liver diseases.
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Affiliation(s)
- Marion Korach-André
- Department of Medicine, Metabolism Unit and Integrated Cardio Metabolic Center (ICMC), Karolinska Institute at Karolinska University Hospital Huddinge, Blickagången 6, NOVUM, Stockholm, 14157, Stockholm, Sweden.
- Clinical Department of Endocrinology, Metabolism and Diabetes, Karolinska University Hospital Huddinge, Stockholm, Sweden.
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4
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Troyanova-Wood M, Gobbell C, Meng Z, Gashev AA, Yakovlev VV. Optical assessment of changes in mechanical and chemical properties of adipose tissue in diet-induced obese rats. JOURNAL OF BIOPHOTONICS 2017; 10:1694-1702. [PMID: 28464472 PMCID: PMC5668206 DOI: 10.1002/jbio.201600281] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/22/2017] [Accepted: 02/24/2017] [Indexed: 05/15/2023]
Abstract
Obesity is becoming a leading cause of health problems world-wide. Obesity and overweight are associated with the structural and chemical changes in tissues; however, few methods exist that allow for concurrent measurement of these changes. Using Brillouin and Raman microspectroscopy, both the mechanical and chemical differences can be assessed simultaneously. We hypothesized that Brillouin spectroscopy can measure the adipose tissues' stiffness, which increases in obesity. Samples of brown and white adipose tissues obtained from control and diet-induced obese adult rats were analyzed. The results show that both adipose tissues of the obese group exhibit a greater high-frequency longitudinal elastic modulus than the control samples, and that the brown fat is generally stiffer than white adipose. The Raman spectra indicate that the lipids' accumulation in adipose tissue outpaces the fibrosis, and that the high-fat diet has a greater effect on the brown adipose than the white fat. Overall, the powerful combination of Brillouin and Raman microspectroscopies successfully assessed both the mechanical properties and chemical composition of adipose tissue simultaneously for the first time. The results indicate that the adipose tissue experiences an obesity-induced increase in stiffness and lipid content, with the brown adipose tissue undergoing a more pronounced change compared to white adipose.
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Affiliation(s)
- Maria Troyanova-Wood
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843-3120, USA
| | - Cassidy Gobbell
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843-3120, USA
| | - Zhaokai Meng
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843-3120, USA
| | - Anatoliy A. Gashev
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, 76504, USA
| | - Vladislav V. Yakovlev
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843-3120, USA
- Corresponding Author:
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5
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Non-invasive Quantitative Analysis of Specific Fat Accumulation in Subcutaneous Adipose Tissues using Raman Spectroscopy. Sci Rep 2016; 6:37068. [PMID: 27845402 PMCID: PMC5109226 DOI: 10.1038/srep37068] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 10/25/2016] [Indexed: 01/22/2023] Open
Abstract
Subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and fat beneath the dermis layer were investigated using a ball lens top hollow optical fiber Raman probe (BHRP). Hamsters were fed with trilinolein (TL) and tricaprin (TC) for six weeks and measurements were carried out every two weeks. The BHRP with an 800 μm diameter fused-silica ball lens was able to obtain information on the subcutaneous fat in a totally non-invasive manner. Changes in the concentration of TL and TC during the treatment were analyzed, and the relationship between fat accumulation and dietary fat was studied. It was found that SAT had, in general, a higher degree of unsaturation than VAT. The accumulation rate of TC found in SAT and VAT was 0.52 ± 0.38 and 0.58 ± 0.4%, respectively, while the TL accumulation rate was 4.45 ± 1.6 and 4.37 ± 2.4%, respectively. The results suggest different metabolic pathways for TC, a typical medium-chain fatty acid, and TL, a long-chain unsaturated fatty acid. Raman subsurface spectra were successfully obtained and used to analyze the subcutaneous fat layer. The accumulation rates of TL and TC found in skin fat were 5.01 ± 3.53% and 0.45 ± 0.36%, respectively. The results demonstrate the high feasibility of Raman spectroscopy for non-invasive analysis of adipose tissue.
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Marzola P, Boschi F, Moneta F, Sbarbati A, Zancanaro C. Preclinical In vivo Imaging for Fat Tissue Identification, Quantification, and Functional Characterization. Front Pharmacol 2016; 7:336. [PMID: 27725802 PMCID: PMC5035738 DOI: 10.3389/fphar.2016.00336] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/12/2016] [Indexed: 12/31/2022] Open
Abstract
Localization, differentiation, and quantitative assessment of fat tissues have always collected the interest of researchers. Nowadays, these topics are even more relevant as obesity (the excess of fat tissue) is considered a real pathology requiring in some cases pharmacological and surgical approaches. Several weight loss medications, acting either on the metabolism or on the central nervous system, are currently under preclinical or clinical investigation. Animal models of obesity have been developed and are widely used in pharmaceutical research. The assessment of candidate drugs in animal models requires non-invasive methods for longitudinal assessment of efficacy, the main outcome being the amount of body fat. Fat tissues can be either quantified in the entire animal or localized and measured in selected organs/regions of the body. Fat tissues are characterized by peculiar contrast in several imaging modalities as for example Magnetic Resonance Imaging (MRI) that can distinguish between fat and water protons thank to their different magnetic resonance properties. Since fat tissues have higher carbon/hydrogen content than other soft tissues and bones, they can be easily assessed by Computed Tomography (CT) as well. Interestingly, MRI also discriminates between white and brown adipose tissue (BAT); the latter has long been regarded as a potential target for anti-obesity drugs because of its ability to enhance energy consumption through increased thermogenesis. Positron Emission Tomography (PET) performed with 18F-FDG as glucose analog radiotracer reflects well the metabolic rate in body tissues and consequently is the technique of choice for studies of BAT metabolism. This review will focus on the main, non-invasive imaging techniques (MRI, CT, and PET) that are fundamental for the assessment, quantification and functional characterization of fat deposits in small laboratory animals. The contribution of optical techniques, which are currently regarded with increasing interest, will be also briefly described. For each technique the physical principles of signal detection will be overviewed and some relevant studies will be summarized. Far from being exhaustive, this review has the purpose to highlight some strategies that can be adopted for the in vivo identification, quantification, and functional characterization of adipose tissues mainly from the point of view of biophysics and physiology.
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Affiliation(s)
- Pasquina Marzola
- Department of Computer Science, University of Verona, VeronaItaly
| | - Federico Boschi
- Department of Computer Science, University of Verona, VeronaItaly
| | - Francesco Moneta
- Preclinical Imaging Division – Bruker BioSpin, Bruker Italia s.r.l, MilanoItaly
| | - Andrea Sbarbati
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, VeronaItaly
| | - Carlo Zancanaro
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, VeronaItaly
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7
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Foca G, Ferrari C, Ulrici A, Ielo MC, Minelli G, Lo Fiego DP. Iodine Value and Fatty Acids Determination on Pig Fat Samples by FT-NIR Spectroscopy: Benefits of Variable Selection in the Perspective of Industrial Applications. FOOD ANAL METHOD 2016. [DOI: 10.1007/s12161-016-0478-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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8
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Minamikawa T, Harada Y, Takamatsu T. Ex vivo peripheral nerve detection of rats by spontaneous Raman spectroscopy. Sci Rep 2015; 5:17165. [PMID: 26602842 PMCID: PMC4658536 DOI: 10.1038/srep17165] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 10/19/2015] [Indexed: 01/17/2023] Open
Abstract
Nerve-sparing surgery is increasingly being applied to avoid functional deficits of the limbs and organs following surgery. Peripheral nerves that should be preserved are, however, sometimes misidentified due to similarity of shape and color to non-nerve tissues. To avoid misidentification of peripheral nerves, development of an in situ nerve detection method is desired. In this study, we report the label-free detection of ex vivo peripheral nerves of Wistar rats by using Raman spectroscopy. We obtained Raman spectra of peripheral nerves (myelinated and unmyelinated nerves) and their adjacent tissues of Wistar rats without any treatment such as fixation and/or staining. For the identification of tissue species and further analysis of spectral features, we proposed a principal component regression-based discriminant analysis with representative Raman spectra of peripheral nerves and their adjacent tissues. Our prediction model selectively detected myelinated nerves and unmyelinated nerves of Wistar rats with respective sensitivities of 95.5% and 88.3% and specificities of 99.4% and 93.5%. Furthermore, important spectral features for the identification of tissue species were revealed by detailed analysis of principal components of representative Raman spectra of tissues. Our proposed approach may provide a unique and powerful tool for peripheral nerve detection for nerve-sparing surgery in the future.
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Affiliation(s)
- Takeo Minamikawa
- Department of Pathology and Cell Regulation, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
| | - Yoshinori Harada
- Department of Pathology and Cell Regulation, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
| | - Tetsuro Takamatsu
- Department of Medical Photonics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
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9
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Soares AF, Lei H, Gruetter R. Characterization of hepatic fatty acids in mice with reduced liver fat by ultra-short echo time (1)H-MRS at 14.1 T in vivo. NMR IN BIOMEDICINE 2015; 28:1009-1020. [PMID: 26119835 DOI: 10.1002/nbm.3345] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 06/04/2023]
Abstract
Alterations in the hepatic lipid content (HLC) and fatty acid composition are associated with disruptions in whole body metabolism, both in humans and in rodent models, and can be non-invasively assessed by (1)H-MRS in vivo. We used (1)H-MRS to characterize the hepatic fatty-acyl chains of healthy mice and to follow changes caused by streptozotocin (STZ) injection. Using STEAM at 14.1 T with an ultra-short TE of 2.8 ms, confounding effects from T2 relaxation and J-coupling were avoided, allowing for accurate estimations of the contribution of unsaturated (UFA), saturated (SFA), mono-unsaturated (MUFA) and poly-unsaturated (PUFA) fatty-acyl chains, number of double bonds, PU bonds and mean chain length. Compared with in vivo (1) H-MRS, high resolution NMR performed in vitro in hepatic lipid extracts reported longer fatty-acyl chains (18 versus 15 carbons) with a lower contribution from UFA (61 ± 1% versus 80 ± 5%) but a higher number of PU bonds per UFA (1.39 ± 0.03 versus 0.58 ± 0.08), driven by the presence of membrane species in the extracts. STZ injection caused a decrease of HLC (from 1.7 ± 0.3% to 0.7 ± 0.1%), an increase in the contribution of SFA (from 21 ± 2% to 45 ± 6%) and a reduction of the mean length (from 15 to 13 carbons) of cytosolic fatty-acyl chains. In addition, SFAs were also likely to have increased in membrane lipids of STZ-induced diabetic mice, along with a decrease of the mean chain length. These studies show the applicability of (1)H-MRS in vivo to monitor changes in the composition of the hepatic fatty-acyl chains in mice even when they exhibit reduced HLC, pointing to the value of this methodology to evaluate lipid-lowering interventions in the scope of metabolic disorders.
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Affiliation(s)
- Ana Francisca Soares
- Laboratory for Functional and Metabolic Imaging (LIFMET), École Polytechinque Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Hongxia Lei
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland
- Department of Radiology, University of Geneva (UNIGE), Geneva, Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging (LIFMET), École Polytechinque Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Department of Radiology, University of Geneva (UNIGE), Geneva, Switzerland
- Department of Radiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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Münchberg U, Wagner L, Spielberg ET, Voigt K, Rösch P, Popp J. Spatially resolved investigation of the oil composition in single intact hyphae of Mortierella spp. with micro-Raman spectroscopy. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:341-9. [PMID: 23032786 DOI: 10.1016/j.bbalip.2012.09.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 09/03/2012] [Accepted: 09/24/2012] [Indexed: 11/25/2022]
Abstract
Zygomycetes are well known for their ability to produce various secondary metabolites. Fungi of the genus Mortierella can accumulate highly unsaturated lipids in large amounts as lipid droplets. However, no information about the spatial distribution or homogeneity of the oil inside the fungi is obtainable to date due to the invasive and destructive analytical techniques applied so far. Raman spectroscopy has been demonstrated to be well suited to investigate biological samples on a micrometre scale. It also has been shown that the degree of unsaturation of lipids can be determined from Raman spectra. We applied micro-Raman spectroscopy to investigate the spatial distribution and composition of lipid vesicles inside intact hyphae. For Mortierella alpina and Mortierella elongata distinct differences in the degree of unsaturation and even the impact of growth conditions are determined from the Raman spectra. In both species we found that the fatty acid saturation in the vesicles is highly variable in the first 600 μm of the growing hyphal tip and fluctuates towards a constant composition and saturation ratio in all of the remaining mycelium. Our approach facilitates in vivo monitoring of the lipid production and allows us to investigate the impact of cultivation parameters on the oil composition directly in the growing hyphae without the need for extensive extraction procedures.
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Affiliation(s)
- Ute Münchberg
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
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11
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Label-free detection of peripheral nerve tissues against adjacent tissues by spontaneous Raman microspectroscopy. Histochem Cell Biol 2012; 139:181-93. [DOI: 10.1007/s00418-012-1015-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2012] [Indexed: 10/28/2022]
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12
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Hepatic lipid composition differs between ob/ob and ob/+ control mice as determined by using in vivo localized proton magnetic resonance spectroscopy. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2012; 25:381-9. [PMID: 22441585 DOI: 10.1007/s10334-012-0310-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 02/24/2012] [Accepted: 02/24/2012] [Indexed: 12/21/2022]
Abstract
OBJECT Hepatic lipid accumulation is associated with nonalcoholic fatty liver disease, and the metabolic syndrome constitutes an increasing medical problem. In vivo proton magnetic resonance spectroscopy ((1)H MRS) allows the assessment of hepatic lipid levels noninvasively and also yields information on the fat composition due to its high spectral resolution. MATERIALS AND METHODS We applied (1)H MRS at 9.4T to study lipid content and composition in eight leptin-deficient ob/ob mice as a model of obesity and in four lean ob/+ control mice at 24 weeks of age. PRESS sequence was used. For accurate estimation of signal intensity, differences in relaxation behavior of individual signals were accounted for each mouse individually. Also, in order to minimize spectral degrading due to motion artifacts, respiration gating was applied. RESULTS Significant differences between ob/ob and ob/+ control mice were found in both lipid content and composition. The mean chain length was found to be significantly longer in ob/ob mice with a higher fraction of monounsaturated lipids. CONCLUSION (1)H MRS enables accurate assessment in hepatic lipids in mice, which is attractive for mechanistic studies of altered metabolism given the large number of genetically engineered mouse models available.
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