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Wang C, Gamage PL, Jiang W, Mudalige T. Excipient-related impurities in liposome drug products. Int J Pharm 2024; 657:124164. [PMID: 38688429 DOI: 10.1016/j.ijpharm.2024.124164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 05/02/2024]
Abstract
Liposomes are widely used in the pharmaceutical industry as drug delivery systems to increase the efficacy and reduce the off-target toxicity of active pharmaceutical ingredients (APIs). The liposomes are more complex drug delivery systems than the traditional dosage forms, and phospholipids and cholesterol are the major structural excipients. These two excipients undergo hydrolysis and/or oxidation during liposome preparation and storage, resulting in lipids hydrolyzed products (LHPs) and cholesterol oxidation products (COPs) in the final liposomal formulations. These excipient-related impurities at elevated concentrations may affect liposome stability and exert biological functions. This review focuses on LHPs and COPs, two major categories of excipient-related impurities in the liposomal formulations, and discusses factors affecting their formation, and analytical methods to determine these excipient-related impurities.
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Affiliation(s)
- Changguang Wang
- Arkansas Laboratory, Office of Regulatory Affairs, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Prabhath L Gamage
- Arkansas Laboratory, Office of Regulatory Affairs, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Wenlei Jiang
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, 20993, USA.
| | - Thilak Mudalige
- Arkansas Laboratory, Office of Regulatory Affairs, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA.
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2
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Sharif NA. PAF-induced inflammatory and immuno-allergic ophthalmic diseases and their mitigation with PAF receptor antagonists: Cell and nuclear effects. Biofactors 2022; 48:1226-1249. [PMID: 35594054 PMCID: PMC10084252 DOI: 10.1002/biof.1848] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/17/2022] [Accepted: 04/26/2022] [Indexed: 02/06/2023]
Abstract
Ocular allergies are becoming more prevalent as more airborne pollutants, irritants and microbes pervade our environment. Inflammatory and allergic mediators released by dendritic and mast cells within the conjunctiva cause allergic conjunctivitis (AC), a prevalent ocular surface disorder that affects >40% of the world's human population on a seasonal or perennial basis. Even though histamine is a major culprit, platelet-activating factor (PAF) also contributes to AC, acting either directly or synergistically with histamine and other mediators. PAF receptor-meditated inflammatory reactions, via cell-membrane-bound and nuclear-membrane-bound and nuclear PAF receptors, are also implicated in the etiology of other eye diseases such as uveitis, diabetic retinopathy, corneal and choroidal neovascularization, and age-related macular degeneration which cause serious visual impairment and can lead to blindness. This review highlights the various deleterious elements implicated in the pathological aspects of ocular allergic reactions and inflammation and provides concepts and treatment options to mitigate these eye disorders with a special focus on PAF and PAF receptor antagonists.
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Affiliation(s)
- Najam A Sharif
- Singapore Eye Research Institute (SERI), Singapore, Singapore
- Department of Pharmacology and Neuroscience, University of North Texas Health Sciences Center, Fort Worth, Texas, USA
- Department of Pharmacy Sciences, Creighton University, Omaha, Nebraska, USA
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, Texas, USA
- Department of Surgery & Cancer, Imperial College of Science and Technology, London, UK
- Duke-National University of Singapore Medical School, SingHealth, Singapore, Singapore
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3
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Badr MY, Halwani AA, Odunze U, Eskandarpour M, Calder VL, Schätzlein AG, Uchegbu IF. The Topical Ocular Delivery of Rapamycin to Posterior Eye Tissues and the Suppression of Retinal Inflammatory Disease. Int J Pharm 2022; 621:121755. [PMID: 35447226 DOI: 10.1016/j.ijpharm.2022.121755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/25/2022] [Accepted: 04/14/2022] [Indexed: 12/01/2022]
Abstract
Treatment of posterior eye diseases with intravitreal injections of drugs, while effective, is invasive and associated with side effects such as retinal detachment and endophthalmitis. In this work, we have formulated a model compound, rapamycin (RAP), in nanoparticle-based eye drops and evaluated the delivery of RAP to the posterior eye tissues in a healthy rabbit. We have also studied the formulation in experimental autoimmune uveitis (EAU) mouse model with retinal inflammation. Aqueous RAP eye drops were prepared using N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (Molecular Envelope Technology - MET) containing 0.23 ± 0.001% w/v RAP with viscosity, osmolarity, and pH within the ocular comfort range, and the formulation (MET-RAP) was stable in terms of drug content at both refrigeration and room temperature for one month. The MET-RAP eye drops delivered RAP to the choroid-retina with a Cmax of 145 ± 49 ng/g (tmax = 1 hour). The topical application of the MET-RAP eye drops to the EAU mouse model resulted in significant disease suppression compared to controls, with activity similar to dexamethasone eye drops. The MET-RAP eye drops also resulted in a reduction of RORγt and an increase in both Foxp3 expression and IL-10 secretion, indicating a mechanism involving the inhibition of Th17 cells and the up-regulation of T-reg cells. The MET-RAP formulation delivers RAP to the posterior eye segments, and the formulation is active in EAU.
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Affiliation(s)
- Moutaz Y Badr
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom; College of Pharmacy, Umm Al-Qura University, Mecca, 24381, Saudi Arabia
| | - Abdulrahman A Halwani
- School of Pharmacy, King Abdulaziz University, Abdullah Sulayman St, Jeddah, 80200, Saudi Arabia
| | - Uchechukwu Odunze
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
| | - Malihe Eskandarpour
- University College London, Institute of Ophthalmology, London EC1V 9EL, United Kingdom
| | - Virginia L Calder
- University College London, Institute of Ophthalmology, London EC1V 9EL, United Kingdom
| | - Andreas G Schätzlein
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom; Nanomerics Ltd., 6th Floor, 2 London Wall Place, London EC2Y 5AU, United Kingdom
| | - Ijeoma F Uchegbu
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom; Nanomerics Ltd., 6th Floor, 2 London Wall Place, London EC2Y 5AU, United Kingdom.
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4
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Engel KM, Prabutzki P, Leopold J, Nimptsch A, Lemmnitzer K, Vos DRN, Hopf C, Schiller J. A new update of MALDI-TOF mass spectrometry in lipid research. Prog Lipid Res 2022; 86:101145. [PMID: 34995672 DOI: 10.1016/j.plipres.2021.101145] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/06/2021] [Accepted: 12/29/2021] [Indexed: 01/06/2023]
Abstract
Matrix-assisted laser desorption and ionization (MALDI) mass spectrometry (MS) is an indispensable tool in modern lipid research since it is fast, sensitive, tolerates sample impurities and provides spectra without major analyte fragmentation. We will discuss some methodological aspects, the related ion-forming processes and the MALDI MS characteristics of the different lipid classes (with the focus on glycerophospholipids) and the progress, which was achieved during the last ten years. Particular attention will be given to quantitative aspects of MALDI MS since this is widely considered as the most serious drawback of the method. Although the detailed role of the matrix is not yet completely understood, it will be explicitly shown that the careful choice of the matrix is crucial (besides the careful evaluation of the positive and negative ion mass spectra) in order to be able to detect all lipid classes of interest. Two developments will be highlighted: spatially resolved Imaging MS is nowadays well established and the distribution of lipids in tissues merits increasing interest because lipids are readily detectable and represent ubiquitous compounds. It will also be shown that a combination of MALDI MS with thin-layer chromatography (TLC) enables a fast spatially resolved screening of an entire TLC plate which makes the method competitive with LC/MS.
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Affiliation(s)
- Kathrin M Engel
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Patricia Prabutzki
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Jenny Leopold
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Ariane Nimptsch
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Katharina Lemmnitzer
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - D R Naomi Vos
- Center for Biomedical Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Paul-Wittsack-Strasse 10, D-68163 Mannheim, Germany
| | - Carsten Hopf
- Center for Biomedical Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Paul-Wittsack-Strasse 10, D-68163 Mannheim, Germany
| | - Jürgen Schiller
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany.
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5
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Chen X, Zhang C, Tian L, Wu L, Jie Y, Wang N, Liu R, Wang L. In situ metabolic profile and spatial distribution of ocular tissues: New insights into dry eye disease. Ocul Surf 2022; 24:51-63. [PMID: 34990847 DOI: 10.1016/j.jtos.2021.12.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 11/21/2021] [Accepted: 12/30/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE Dry eye disease (DED) is a chronic multifactorial disorder affecting millions of people, yet the pathogenesis mechanisms still remain unclear. Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) is a novel in situ visualization approach combined high-throughput mass spectrometry and molecular imaging. We aimed to explore the in situ ocular metabolic changes via MALDI-MSI to accelerate the recognition of DED pathogenesis. METHODS Experimental dry eye was established in Wistar rats by subcutaneous injection of scopolamine. The induction of DED was assessed by tear film breakup time, sodium fluorescein, histopathological staining and cell apoptosis. MALDI-MSI was applied to explore in situ ocular metabolomic in DED rats, and histopathological staining from same sections were used for side-by-side comparison with MALDI to annotate different tissue structures in the eye. RESULTS Considering the complexity of ocular tissue, we visualized the metabolites in specific ocular regions (central cornea, peripheral cornea, fornix conjunctiva, eyelid conjunctiva and aqueous humor), and identified metabolites related to DED, with information of relative abundance and spatial signatures. In addition, integrative pathway analysis illustrated that, several metabolic pathways such as glycerophospholipid, sphingolipid phenylalanine, and metabolism of glycine, serine and threonine were significantly altered in certain regions in the dry eye tissue. Moreover, we discussed how the metabolic pathways with spatiotemporal signatures might be involved in the DED process. CONCLUSIONS Our data exploit the advantages of in situ analysis of MALDI-MSI to accurately analyze the region-specific metabolic behaviors in DED, and provide new clues to uncover DED pathogenesis.
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Affiliation(s)
- Xiaoniao Chen
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Hospital, Capital Medical University, Beijing, China; State Key Laboratory of Kidney Diseases, Chinese PLA General Hospital, Beijing, China; Senior Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China.
| | - Chuyue Zhang
- State Key Laboratory of Kidney Diseases, Chinese PLA General Hospital, Beijing, China
| | - Lei Tian
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Lingling Wu
- State Key Laboratory of Kidney Diseases, Chinese PLA General Hospital, Beijing, China
| | - Ying Jie
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ran Liu
- State Key Laboratory of Kidney Diseases, Chinese PLA General Hospital, Beijing, China
| | - Liqiang Wang
- State Key Laboratory of Kidney Diseases, Chinese PLA General Hospital, Beijing, China; Senior Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China.
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Gao Y, Qi Y, Huang Y, Li X, Zhou L, Zhao S. Lipidomics Analysis of the Tears in the Patients Receiving LASIK, FS-LASIK, or SBK Surgery. Front Med (Lausanne) 2021; 8:731462. [PMID: 34778293 PMCID: PMC8579130 DOI: 10.3389/fmed.2021.731462] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 09/24/2021] [Indexed: 01/17/2023] Open
Abstract
Purpose: Tear film lipid layer (TFLL) plays a vital role in maintaining the tear film stability and, thus, the lipid composition of the tears could greatly affect the physiological function and biophysical integrity of the tear film. The objective of this study is to assess the tear lipid composition of the patients receiving laser-assisted in situ keratomileusis (LASIK), femtosecond LASIK (FS-LASIK), or sub-Bowman's keratomileusis (SBK) surgery preoperatively and postoperatively. Methods: Tear samples were collected from the left eye of the patient who receiving LASIK (n = 10), FS-LASIK (n = 10), or SBK (n = 10) surgery in week 0, week 1, week 4, and week 52. A rapid direct injection shotgun lipidomics workflow, MS/MSALL (<2 min/sample), was applied to examine the tear lipidome. Results: In week 52, the SBK group demonstrated a similar lipidome profile compared to week 0, while the FS-LASIK and LASIK groups shifted away from week 0. Two lipids, ganglioside (GD3) 27:4 and triacylglycerol (TAG) 59:3, were found to be associated with the lipidome changes preoperatively and postoperatively. No statistical significance was found in the overall lipid classes from the FS-LASIK group. The LASIK group showed significant alteration in the phospholipid and sphingolipid over time, while the SBK group demonstrated a significant difference in the (O-acyl)-ω-hydroxy fatty acid (OAHFA) and phospholipid. Conclusion: LASIK showed the greatest impact on the tear lipidome changes over time, while SBK demonstrated minimal impact among the three types of refractive surgeries after 1 year.
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Affiliation(s)
- Yan Gao
- Ocular Proteomics Platform, Singapore Eye Research Institute, Singapore, Singapore
| | - Yuanyuan Qi
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Yue Huang
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Xiaorong Li
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Lei Zhou
- Ocular Proteomics Platform, Singapore Eye Research Institute, Singapore, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Ophthalmology and Visual Sciences Academia Clinical Program, Duke-National University of Singapore Medical School, Singapore, Singapore
| | - Shaozhen Zhao
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
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7
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Zhang T, Hu L, Ma H, Ni F, Liu F, Chen H. Detection of Tear Components Using Matrix-Assisted Laser Desorption Ionization/Time-of-Flight Mass Spectrometry for Rapid Dry Eye Diagnosis. J Proteome Res 2020; 19:3644-3651. [PMID: 32786892 DOI: 10.1021/acs.jproteome.0c00138] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The tear is a biological fluid that has the diagnostic potential for ocular diseases. Extracellular vesicles (EVs), widly detected in various biofluids including tears, are nanoparticles released by living cells and considered as promising detection sources for noninvasive liquid biopsy. Understanding the roles of tears and tear-EVs in ocular diseases such as dry eye can facilitate the studies of clinical diagnosis, which usually entails detecting such liquid objects with a rapid and effective method. In this study, we used a mass spectrometry-based strategy to analyze peptidome/proteome profiles of tears and EVs for rapid dry eye diagnosis. Nanosized EVs were isolated from tears of both healthy control (HC) individuals and dry eye syndrome (DES) patients, and the tear compositions were further analyzed by tracking their fingerprints with matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. The fingerprints of tear-EVs could be observed in a dose-dependent manner and tears, allowing for comparison of the discriminant peaks between tears and EVs. By analyzing these peaks, the fingerprints of both tear and tear-EVs were showed to have the capability of distinguishing patients with DES from HC donors and providing an efficient way for screening potential DES biomarkers. The proposed tear and EV fingerprinting approach is expected to be a potential tool in the rapid diagnosis of ocular diseases and in-depth research on pathogenesis. Data are available via ProteomeXchange with identifier PXD020217.
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Affiliation(s)
- Ting Zhang
- School of Ophthalmology & Optometry, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Liang Hu
- School of Ophthalmology & Optometry, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Huixiang Ma
- School of Ophthalmology & Optometry, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Fangfang Ni
- School of Ophthalmology & Optometry, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Fei Liu
- School of Ophthalmology & Optometry, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.,Wenzhou Institute, University of Chinese Academy of Science, Wenzhou, Zhejiang 325001, China
| | - Hao Chen
- School of Ophthalmology & Optometry, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
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Jones L, Downie LE, Korb D, Benitez-del-Castillo JM, Dana R, Deng SX, Dong PN, Geerling G, Hida RY, Liu Y, Seo KY, Tauber J, Wakamatsu TH, Xu J, Wolffsohn JS, Craig JP. TFOS DEWS II Management and Therapy Report. Ocul Surf 2017; 15:575-628. [DOI: 10.1016/j.jtos.2017.05.006] [Citation(s) in RCA: 578] [Impact Index Per Article: 82.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 02/06/2023]
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Carmical J, Brown S. The impact of phospholipids and phospholipid removal on bioanalytical method performance. Biomed Chromatogr 2016; 30:710-20. [DOI: 10.1002/bmc.3686] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/11/2016] [Accepted: 01/13/2016] [Indexed: 01/19/2023]
Affiliation(s)
- Jennifer Carmical
- Bill Gatton College of Pharmacy, East Tennessee State University; Department of Pharmaceutical Sciences; Johnson City TN 37614 USA
| | - Stacy Brown
- Bill Gatton College of Pharmacy, East Tennessee State University; Department of Pharmaceutical Sciences; Johnson City TN 37614 USA
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11
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Pucker AD, Haworth KM. The Presence and Significance of Polar Meibum and Tear Lipids. Ocul Surf 2015; 13:26-42. [DOI: 10.1016/j.jtos.2014.06.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 05/27/2014] [Accepted: 06/01/2014] [Indexed: 01/13/2023]
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12
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Kim SJ, Back SH, Koh JM, Yoo HJ. Quantitative determination of major platelet activating factors from human plasma. Anal Bioanal Chem 2014; 406:3111-8. [PMID: 24682147 DOI: 10.1007/s00216-014-7736-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 02/26/2014] [Accepted: 02/27/2014] [Indexed: 12/20/2022]
Abstract
Platelet activating factor (PAF) is a potent lipid mediator that is involved in many important biological functions, including platelet aggregation and neuronal differentiation. Although an ELISA assay has been used to measure PAF levels, it cannot distinguish between its isoforms. To achieve this, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been used instead. However, isobaric lysophosphatidylcholine (lyso PC), which is often present in large amounts in complex biological samples and has similar retention times in many LC conditions, can affect the accurate measurement of PAF. The present study examined the fragmentation behavior of major PAF and lyso PC during various MS/MS conditions. Fragment ions at m/z 184 and at m/z 104 were abundantly observed from MS/MS of lyso PCs. PAF provided a dominant fragment ion at m/z 184, but a fragment ion at m/z 104 was almost never produced, regardless of the collision energy. Thus, the two fragment ions at m/z 184 and m/z 104 were used to accurately measure PAF levels. First, the fragment ion at m/z 184 and the retention time of PAF in LC-MS/MS were used to identify and quantitate PAF. However, if there were small retention time shifts, which are common in multiple sample runs, and lipid composition in a sample is very complicated, the fragment ion at m/z 104 was used to confirm whether the fragment ion at m/z 184 belonged to PAF. This novel method accurately determined the major PAF (C16:0 PAF, C18:0 PAF, and C18:1 PAF) levels in human plasma.
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Affiliation(s)
- Su Jung Kim
- Biomedical Research Center, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, 138-736, Republic of Korea
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13
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Lam SM, Tong L, Duan X, Petznick A, Wenk MR, Shui G. Extensive characterization of human tear fluid collected using different techniques unravels the presence of novel lipid amphiphiles. J Lipid Res 2013; 55:289-98. [PMID: 24287120 DOI: 10.1194/jlr.m044826] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The tear film covers the anterior eye and the precise balance of its various constituting components is critical for maintaining ocular health. The composition of the tear film amphiphilic lipid sublayer, in particular, has largely remained a matter of contention due to the limiting concentrations of these lipid amphiphiles in tears that render their detection and accurate quantitation tedious. Using systematic and sensitive lipidomic approaches, we validated different tear collection techniques and report the most comprehensive human tear lipidome to date; comprising more than 600 lipid species from 17 major lipid classes. Our study confers novel insights to the compositional details of the existent tear film model, in particular the disputable amphiphilic lipid sublayer constituents, by demonstrating the presence of cholesteryl sulfate, O-acyl-ω-hydroxyfatty acids, and various sphingolipids and phospholipids in tears. The discovery and quantitation of the relative abundance of various tear lipid amphiphiles reported herein are expected to have a profound impact on the current understanding of the existent human tear film model.
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Affiliation(s)
- Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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14
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Analysis of Meibum and Tear Lipids. Ocul Surf 2012; 10:230-50. [DOI: 10.1016/j.jtos.2012.07.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/16/2012] [Accepted: 07/01/2012] [Indexed: 11/19/2022]
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15
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Tear analysis and lens-tear interactions: part II. Ocular lipids-nature and fate of meibomian gland phospholipids. Cornea 2011; 30:325-32. [PMID: 21304291 DOI: 10.1097/ico.0b013e3181eae239] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Published data indicate that the polar lipid content of human meibomian gland secretions (MGS) could be anything between 0.5% and 13% of the total lipid. The tear film phospholipid composition has not been studied in great detail and it has been understood that the relative proportions of lipids in MGS would be maintained in the tear film. The purpose of this work was to determine the concentration of phospholipids in the human tear film. METHODS Liquid chromatography mass spectrometry (LCMS) and thin layer chromatography (TLC) were used to determine the concentration of phospholipid in the tear film. Additionally, an Amplex Red phosphatidylcholine-specific phospholipase C (PLC) assay kit was used for determination of the activity of PLC in the tear film. RESULTS Phospholipids were not detected in any of the tested human tear samples with the low limit of detection being 1.3 μg/mL for TLC and 4 μg/mL for liquid chromatography mass spectrometry. TLC indicated that diacylglycerol (DAG) may be present in the tear film. PLC was in the tear film with an activity determined at approximately 15 mU/mL, equivalent to the removal of head groups from phosphatidylcholine at a rate of approximately 15 μM/min. CONCLUSIONS This work shows that phospholipid was not detected in any of the tested human tear samples (above the lower limits of detection as described) and suggests the presence of DAG in the tear film. DAG is known to be at low concentrations in MGS. These observations indicate that PLC may play a role in modulating the tear film phospholipid concentration.
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17
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Tomlinson A, Bron AJ, Korb DR, Amano S, Paugh JR, Pearce EI, Yee R, Yokoi N, Arita R, Dogru M. The international workshop on meibomian gland dysfunction: report of the diagnosis subcommittee. Invest Ophthalmol Vis Sci 2011; 52:2006-49. [PMID: 21450918 DOI: 10.1167/iovs.10-6997f] [Citation(s) in RCA: 571] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Alan Tomlinson
- Department of Vision Sciences, Glasgow Caledonian University, Glasgow, Scotland, United Kingdom
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18
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Green-Church KB, Butovich I, Willcox M, Borchman D, Paulsen F, Barabino S, Glasgow BJ. The international workshop on meibomian gland dysfunction: report of the subcommittee on tear film lipids and lipid-protein interactions in health and disease. Invest Ophthalmol Vis Sci 2011; 52:1979-93. [PMID: 21450916 DOI: 10.1167/iovs.10-6997d] [Citation(s) in RCA: 222] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Kari B Green-Church
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210-1280, USA
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Pitt WG, Jack DR, Zhao Y, Nelson JL, Pruitt JD. Transport of phospholipid in silicone hydrogel contact lenses. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2011; 23:527-41. [PMID: 21310106 DOI: 10.1163/092050611x554174] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Characterization of the transport and release of phospholipids from a silicone hydrogel contact lens is required to assess the possible use of these lenses for phospholipid delivery to increase patient comfort. Contact lenses of silicone hydrogel composition were loaded with varying amounts of radiolabeled 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) from a solution of n-propanol. These lenses were eluted at 35°C into artificial tear fluid (ATF) or ATF containing varying amounts of DMPC. The amount of DMPC loaded into a lens is a linear function of the time of exposure to the DMPC/propanol solution. The initial rate of elution into ATF appears to be diffusion controlled for at least 10 h and is proportional to the amount of DMPC loaded. The elution rate decreases as the DMPC concentration in the ATF increases. The ease of loading and the controllable release of DMPC from silicone hydrogels presents the possibility of using such lenses to counter eye discomfort caused by inherently low levels of phospholipid in tears.
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Affiliation(s)
- William G Pitt
- Chemical Engineering Department, 350 Clyde Building, Brigham Young University, Provo, UT 84602, USA.
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Fuchs B, Süss R, Schiller J. An update of MALDI-TOF mass spectrometry in lipid research. Prog Lipid Res 2010; 49:450-75. [PMID: 20643161 DOI: 10.1016/j.plipres.2010.07.001] [Citation(s) in RCA: 212] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 06/29/2010] [Accepted: 07/01/2010] [Indexed: 10/19/2022]
Abstract
Although matrix-assisted laser desorption and ionization (MALDI) mass spectrometry (MS)--often but not exclusively coupled with a time-of-flight (TOF) mass analyzer--is primarily established in the protein field, there is increasing evidence that MALDI MS is also very useful in lipid research: MALDI MS is fast, sensitive, tolerates sample impurities to a relatively high extent and provides very simple mass spectra without major fragmentation of the analyte. Additionally, MALDI MS devices originally purchased for "proteomics" can be used also for lipids without the need of major system alterations. After a short introduction into the method and the related ion-forming process, the MALDI mass spectrometric characteristics of the individual lipid (ranging from completely apolar hydrocarbons to complex glycolipids with the focus on glycerophospholipids) classes will be discussed and the progress achieved in the last years emphasized. Special attention will be paid to quantitative aspects of MALDI MS because this is normally considered to be the "weak" point of the method, particularly if complex lipid mixtures are to be analyzed. Although the detailed role of the matrix is not yet completely clear, it will be also explicitly shown that the careful choice of the matrix is crucial in order to be able to detect all compounds of interest. Two rather recent developments will be highlighted: "Imaging" MS is nowadays widely established and significant interest is paid in this context to the analysis of lipids because lipids ionize particularly well and are, thus, more sensitively detectable in tissue slices than other biomolecules such as proteins. It will also be shown that MALDI MS can be very easily combined with thin-layer chromatography (TLC) allowing the spatially-resolved screening of the entire TLC plate and the detection of lipids with a higher sensitivity than common staining protocols.
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Affiliation(s)
- Beate Fuchs
- University of Leipzig, Medical Department, Institute of Medical Physics and Biophysics, Härtelstrasse 16-18, Germany
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Xu F, Zou L, Lin Q, Ong CN. Use of liquid chromatography/tandem mass spectrometry and online databases for identification of phosphocholines and lysophosphatidylcholines in human red blood cells. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:3243-3254. [PMID: 19725045 DOI: 10.1002/rcm.4246] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In this work a systematic strategy integrating liquid chromatography/tandem mass spectrometry (LC/MS/MS) and online databases was developed to identify phosphocholines (PC) and lysophosphatidylcholines (LPC) in human red blood cells (RBCs). First of all, the neutral loss scan of 59 and the precursor ion scan of m/z 184 were performed to find out the possible lipids with phosphocholine head-group structure in RBCs. The acquired [M+H](+) and [M+Na](+) adduct ions were then identified online using the Human Metabolome Database (HMDB) and the LIPID MAPS, which were then further confirmed by their MS/MS fragmentation. Based on the comparison of chemical structures of the detected PC and LPC with their corresponding MS/MS fragmentation pathways, several new diagnostic fragments or fragmentation pathway were found. These include, (1) the neutral losses of 183 could be used as a diagnostic fragmentation to discriminate PC and LPC; (2) product ions at m/z 104 could be used to distinguish LPC and their sn-2 isomers; (3) fragment ions at m/z 184 are characteristic fragmentation that could be used for discrimination of sodiated ions [M+Na](+) and protonated ions [M+H](+), especially for co-eluted PC or LPC with a molecular weight difference of 22. The structures of the above-mentioned fragment ions were confirmed by quadrupole time-of-flight (Q-TOF) MS. Furthermore, a PC and LPC focused LC/MS semi-quantification approach was also developed and validated. This approach could be useful for future lipidomic study.
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Affiliation(s)
- Fengguo Xu
- Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117597
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Haynes CA, Allegood JC, Park H, Sullards MC. Sphingolipidomics: methods for the comprehensive analysis of sphingolipids. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:2696-708. [PMID: 19147416 PMCID: PMC2765038 DOI: 10.1016/j.jchromb.2008.12.057] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 12/23/2008] [Accepted: 12/24/2008] [Indexed: 01/04/2023]
Abstract
Sphingolipids comprise a highly diverse and complex class of molecules that serve as both structural components of cellular membranes and signaling molecules capable of eliciting apoptosis, differentiation, chemotaxis, and other responses in mammalian cells. Comprehensive or "sphingolipidomic" analyses (structure specific, quantitative analyses of all sphingolipids, or at least all members of a critical subset) are required in order to elucidate the role(s) of sphingolipids in a given biological context because so many of the sphingolipids in a biological system are inter-converted structurally and metabolically. Despite the experimental challenges posed by the diversity of sphingolipid-regulated cellular responses, the detection and quantitation of multiple sphingolipids in a single sample has been made possible by combining classical analytical separation techniques such as high-performance liquid chromatography (HPLC) with state-of-the-art tandem mass spectrometry (MS/MS) techniques. As part of the Lipid MAPS consortium an internal standard cocktail was developed that comprises the signaling metabolites (i.e. sphingoid bases, sphingoid base-1-phosphates, ceramides, and ceramide-1-phosphates) as well as more complex species such as mono- and di-hexosylceramides and sphingomyelin. Additionally, the number of species that can be analyzed is growing rapidly with the addition of fatty acyl Co-As, sulfatides, and other complex sphingolipids as more internal standards are becoming available. The resulting LC-MS/MS analyses are one of the most analytically rigorous technologies that can provide the necessary sensitivity, structural specificity, and quantitative precision with high-throughput for "sphingolipidomic" analyses in small sample quantities. This review summarizes historical and state-of-the-art analytical techniques used for the identification, structure determination, and quantitation of sphingolipids from free sphingoid bases through more complex sphingolipids such as sphingomyelins, lactosylceramides, and sulfatides including those intermediates currently considered sphingolipid "second messengers". Also discussed are some emerging techniques and other issues remaining to be resolved for the analysis of the full sphingolipidome.
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Affiliation(s)
- Christopher A. Haynes
- School of Biology, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, U.S.A
| | - Jeremy C. Allegood
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-5048, U.S.A
| | - Hyejung Park
- School of Biology, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, U.S.A
| | - M. Cameron Sullards
- School of Biology, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, U.S.A
- School of Chemistry & Biochemistry, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, U.S.A
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Abstract
PURPOSE This review is intended to bring to the informed reader the current state of knowledge about meibomian lipids and the art for analyzing them. METHODS At the forefront of any endeavor, there are controversies, and these, along with future directions in the field, are brought to the reader's attention. RESULTS Function and anatomy of meibomian glands are briefly covered, giving insight into possible mechanisms for secretory controls. Anatomically, some anomalies in meibomian gland distribution of different species, such as whales versus dolphins, are presented, and, for the first time, the structure of the meibomian glands in a selection of marsupials is presented. In attempting to make the literature more accessible, lipid structure and nomenclature are described, and these structures are related to their possible effects on the physicochemical properties of meibomian lipids. The advantages and disadvantages of various collection and storage techniques are described, as well as how gas chromatography and combined HPLC and mass spectrometry coupled with fragmentation are currently enabling us to determine the nature of the lipids in very small samples. CONCLUSIONS This review extends to discussing the lipids in tears (as opposed to meibomian gland lipids) and briefly highlights new thoughts about the interactions between proteins of the tear film and meibomian lipids. A model that includes proteins in the outer layer of the tear film is also presented. This model is currently being critically analyzed by the ocular community. It concludes briefly by highlighting possible further areas of research in this area.
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Affiliation(s)
- Igor A Butovich
- Department of Ophthalmology and Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Lam TC, Chun RKM, Li KK, To CH. Application of proteomic technology in eye research: a mini review. Clin Exp Optom 2008; 91:23-33. [PMID: 18045249 DOI: 10.1111/j.1444-0938.2007.00194.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Proteomics is a rapidly growing research area for the study of the protein cognate of genomic data. This review gives a brief overview of the modern proteomic technology. In addition to general applications of proteomics, we highlight its contribution to studying the physiology of different ocular tissues. We also summarise the published proteomic literature in the broad context of ophthalmic diseases, such as cataract, age-related maculopathy, diabetic retinopathy, glaucoma and myopia. The proteomic technology is a useful research tool and it will continue to advance our understanding of a variety of molecular processes in ocular tissues and diseases.
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Affiliation(s)
- Thomas C Lam
- Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China
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Ma X, Liu G, Wang S, Chen Z, Lai M, Liu Z, Yang J. Evaluation of sphingolipids changes in brain tissues of rats with pentylenetetrazol-induced kindled seizures using MALDI-TOF-MS. J Chromatogr B Analyt Technol Biomed Life Sci 2007; 859:170-7. [DOI: 10.1016/j.jchromb.2007.09.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2007] [Revised: 09/15/2007] [Accepted: 09/19/2007] [Indexed: 11/16/2022]
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Butovich IA, Uchiyama E, McCulley JP. Lipids of human meibum: mass-spectrometric analysis and structural elucidation. J Lipid Res 2007; 48:2220-35. [PMID: 17626978 DOI: 10.1194/jlr.m700237-jlr200] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The purpose of this study was to structurally characterize the major lipid species present in human meibomian gland secretions (MGS) of individual subjects by means of ion trap atmospheric pressure ionization mass spectrometry analysis (API MS(n)). The samples of MGS and authentic lipid standards were analyzed in direct infusion and high-pressure liquid chromatography (HPLC) experiments with API MS(n) detection of the analytes (HPLC API MS(n)). The major precursor ions were isolated and subjected to further sequential fragmentation in MS(n) experiments, and their fragmentation patterns were compared with those of authentic lipid standards. Multiple precursor ions were observed in the positive-ion mode. Among those, previously identified cholesterol (Chl; m/z 369; [M - H(2)O + H](+)) and oleic acid (OA; m/z 283; [M + H](+)) were found. The other major compounds of the general molecular formula C(n)H(2n-2)O(2) were consistent with wax esters (WEs), with OA as fatty acyl component. Accompanying them were two homologous series of compounds that fit the molecular formulas C(n)H(2n-4)O(2) and C(n)H(2n)O(2). Subset 2 was found to be a homolog series of linoleic acid-based WEs, whereas subset 3 was, apparently, a mixture of stearic acid-based WEs. HPLC API MS(n) analysis revealed the presence of large quantities of cholesteryl esters (Chl-Es) in all of the tested samples. Less than 0.1% (w/w) of oleamide was detected in human MGS. In the negative-ion mode, three major compounds with m/z values of 729, 757, and 785 that were apparently related to anionogenic lipids of the diacylglyceryl family were found in all of the samples. Common phospholipids and ceramides (Cers) were not present among the major MGS lipids. Phosphocholine-based lipids were found in MGS in quantities less than 0.01% (w/w), if at all. This ratio is two orders of magnitude lower than reported previously. These observations suggest that MGS are a major source of nonpolar lipids of the WE and Chl-E families for the tear film lipid layer, but not of its previously reported (phospho)lipid, Cer, and fatty acid amide components.
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Affiliation(s)
- Igor A Butovich
- Department of Ophthalmology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9057, USA.
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Butovich IA, Uchiyama E, Di Pascuale MA, McCulley JP. Liquid chromatography-mass spectrometric analysis of lipids present in human meibomian gland secretions. Lipids 2007; 42:765-76. [PMID: 17605062 DOI: 10.1007/s11745-007-3080-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 05/27/2007] [Indexed: 11/30/2022]
Abstract
The purpose of the study was to qualitatively characterize the major lipid species present in human meibomian gland secretions (MGS) by means of high-performance liquid chromatography with atmospheric pressure ionization mass spectrometric detection of the analytes (NP HPLC-MS). Two different NP HPLC-MS methods have been developed to analyze lipid species that were expected to be present in MGS. The first method was optimized for the analysis of relatively nonpolar lipids [wax esters (WE), di- and triacyl glycerols (DAG and TAG), cholesterol (Chl) and its esters (Chl-E), and ceramides (Cer)], while the second method was designed to separate and detect phospholipids. The major lipid species in MGS were found to be WE, Chl-E, and TAG. A minor amount of free Chl (less then 0.5% of the Chl-E fraction) was detected in MGS. No appreciable amounts of DAG and Cer were found in MGS. The second NP HPLC-MS method, capable of analyzing model mixtures of authentic phospholipids (e.g. phosphatidylglycerol, phosphatidylethanolamine, phosphatidic acid, phosphatidylinositol, phosphatidylserine, phosphatidylcholine, and sphingomyelin) in submicrogram/mL concentrations, showed little or no presence of these species in the MGS samples. These observations suggest that MGS are a major source of the nonpolar lipids of the WE and Chl-E families for the tear film lipid layer (TFLL), but not of the previously reported phospholipid components of the TFLL.
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Affiliation(s)
- Igor A Butovich
- Department of Ophthalmology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9057, USA.
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:547-558. [PMID: 17385794 DOI: 10.1002/jms.1073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Richter K, Nygren H, Malmberg P, Hagenhoff B. Localization of Fatty Acids with Selective Chain Length by Imaging Time-of-Flight Secondary Ion Mass Spectrometry. Microsc Res Tech 2007; 70:640-7. [PMID: 17393479 DOI: 10.1002/jemt.20450] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Localization of fatty acids in biological tissues was made by using TOF-SIMS (time-of-flight secondary ion mass spectrometry). Two cell-types with a specific fatty acid distribution are shown. In rat cerebellum, different distribution patterns of stearic acid (C18:0), palmitic acid (C16:0), and oleic acid (C18:1) were found. Stearic acid signals were observed accumulated in Purkinje cells with high intensities inside the cell, but not in the nucleus region. The signals colocalized with high intensity signals of the phosphocholine head group, indicating origin from phosphatidylcholine or sphingomyelin. In mouse intestine, high palmitic acid signals were found in the secretory crypt cells together with high levels of phosphorylinositol colocalized in the crypt region. Palmitic acid was also seen in the intestinal lumen that contains high amounts of mucine, which is known to be produced in the crypt cells. Linoleic acid signals (C18:2) were low in the crypt region and high in the villus region. Oleic acid signals were seen in the villi and stearic acid signals were ubiquitous with no specific localization in the intestine. We conclude that the results obtained by using imaging TOF-SIMS are consistent with known brain and intestine biochemistry and that the localization of fatty acids is specific in differentiated cells.
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Affiliation(s)
- Katrin Richter
- Department of Biomedicine, Sahlgrenska Academy, Göteborg University, Göteborg, Sweden
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