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Liu H, Yao M, Ren J. Codonopsis pilosula-derived glycopeptide dCP1 promotes the polarization of tumor-associated macrophage from M2-like to M1 phenotype. Cancer Immunol Immunother 2024; 73:128. [PMID: 38743074 PMCID: PMC11093951 DOI: 10.1007/s00262-024-03694-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 03/28/2024] [Indexed: 05/16/2024]
Abstract
The majority of the immune cell population in the tumor microenvironment (TME) consists of tumor-associated macrophages (TAM), which are the main players in coordinating tumor-associated inflammation. TAM has a high plasticity and is divided into two main phenotypes, pro-inflammatory M1 type and anti-inflammatory M2 type, with tumor-suppressive and tumor-promoting functions, respectively. Considering the beneficial effects of M1 macrophages for anti-tumor and the high plasticity of macrophages, the conversion of M2 TAM to M1 TAM is feasible and positive for tumor treatment. This study sought to evaluate whether the glycopeptide derived from simulated digested Codonopsis pilosula extracts could regulate the polarization of M2-like TAM toward the M1 phenotype and the potential regulatory mechanisms. The results showed that after glycopeptide dCP1 treatment, the mRNA relative expression levels of some M2 phenotype marker genes in M2-like TAM in simulated TME were reduced, and the relative expression levels of M1 phenotype marker genes and inflammatory factor genes were increased. Analysis of RNA-Seq of M2-like TAM after glycopeptide dCP1 intervention showed that the gene sets such as glycolysis, which is associated with macrophage polarization in the M1 phenotype, were significantly up-regulated, whereas those of gene sets such as IL-6-JAK-STAT3 pathway, which is associated with polarization in the M2 phenotype, were significantly down-regulated. Moreover, PCA analysis and Pearson's correlation also indicated that M2-like TAM polarized toward the M1 phenotype at the transcriptional level after treatment with the glycopeptide dCP1. Lipid metabolomics was used to further explore the efficacy of the glycopeptide dCP1 in regulating the polarization of M2-like TAM to the M1 phenotype. It was found that the lipid metabolite profiles in dCP1-treated M2-like TAM showed M1 phenotype macrophage lipid metabolism profiles compared with blank M2-like TAM. Analysis of the key differential lipid metabolites revealed that the interconversion between phosphatidylcholine (PC) and diacylglycerol (DG) metabolites may be the central reaction of the glycopeptide dCP1 in regulating the conversion of M2-like TAM to the M1 phenotype. The above results suggest that the glycopeptide dCP1 has the efficacy to regulate the polarization of M2-like TAM to M1 phenotype in simulated TME.
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Affiliation(s)
- Hongxu Liu
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, Guangdong, People's Republic of China
| | - Maojin Yao
- State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, People's Republic of China.
| | - Jiaoyan Ren
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, Guangdong, People's Republic of China.
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2
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Zhong X, Moresco JJ, Diedrich JK, Pinto AM, SoRelle JA, Wang J, Keller K, Ludwig S, Moresco EMY, Beutler B, Choi JH. Essential role of MFSD1-GLMP-GIMAP5 in lymphocyte survival and liver homeostasis. Proc Natl Acad Sci U S A 2023; 120:e2314429120. [PMID: 38055739 PMCID: PMC10723049 DOI: 10.1073/pnas.2314429120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/07/2023] [Indexed: 12/08/2023] Open
Abstract
We detected ENU-induced alleles of Mfsd1 (encoding the major facilitator superfamily domain containing 1 protein) that caused lymphopenia, splenomegaly, progressive liver pathology, and extramedullary hematopoiesis (EMH). MFSD1 is a lysosomal membrane-bound solute carrier protein with no previously described function in immunity. By proteomic analysis, we identified association between MFSD1 and both GLMP (glycosylated lysosomal membrane protein) and GIMAP5 (GTPase of immunity-associated protein 5). Germline knockout alleles of Mfsd1, Glmp, and Gimap5 each caused lymphopenia, liver pathology, EMH, and lipid deposition in the bone marrow and liver. We found that the interactions of MFSD1 and GLMP with GIMAP5 are essential to maintain normal GIMAP5 expression, which in turn is critical to support lymphocyte development and liver homeostasis that suppresses EMH. These findings identify the protein complex MFSD1-GLMP-GIMAP5 operating in hematopoietic and extrahematopoietic tissues to regulate immunity and liver homeostasis.
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Affiliation(s)
- Xue Zhong
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - James J. Moresco
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Jolene K. Diedrich
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA92037
| | - Antonio M. Pinto
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA92037
| | - Jeffrey A. SoRelle
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Jianhui Wang
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Katie Keller
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Sara Ludwig
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Eva Marie Y. Moresco
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Bruce Beutler
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Jin Huk Choi
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX75390
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3
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Kim Y, Mavodza G, Senkal CE, Burd CG. Cholesterol-dependent homeostatic regulation of very long chain sphingolipid synthesis. J Cell Biol 2023; 222:e202308055. [PMID: 37787764 PMCID: PMC10547602 DOI: 10.1083/jcb.202308055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/08/2023] [Accepted: 09/18/2023] [Indexed: 10/04/2023] Open
Abstract
Sphingomyelin plays a key role in cellular cholesterol homeostasis by binding to and sequestering cholesterol in the plasma membrane. We discovered that synthesis of very long chain (VLC) sphingomyelins is inversely regulated by cellular cholesterol levels; acute cholesterol depletion elicited a rapid induction of VLC-sphingolipid synthesis, increased trafficking to the Golgi apparatus and plasma membrane, while cholesterol loading reduced VLC-sphingolipid synthesis. This sphingolipid-cholesterol metabolic axis is distinct from the sterol responsive element binding protein pathway as it requires ceramide synthase 2 (CerS2) activity, epidermal growth factor receptor signaling, and was unaffected by inhibition of protein translation. Depletion of VLC-ceramides reduced plasma membrane cholesterol content, reduced plasma membrane lipid packing, and unexpectedly resulted in the accumulation of cholesterol in the cytoplasmic leaflet of the lysosome membrane. This study establishes the existence of a cholesterol-sphingolipid regulatory axis that maintains plasma membrane lipid homeostasis via regulation of sphingomyelin synthesis and trafficking.
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Affiliation(s)
- Yeongho Kim
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - Grace Mavodza
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Can E. Senkal
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
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Nguyen TTM, Nguyen TH, Kim HS, Dao TTP, Moon Y, Seo M, Kang S, Mai VH, An YJ, Jung CR, Kim JM, Park S. GPX8 regulates clear cell renal cell carcinoma tumorigenesis through promoting lipogenesis by NNMT. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2023; 42:42. [PMID: 36750850 PMCID: PMC9903620 DOI: 10.1186/s13046-023-02607-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 01/19/2023] [Indexed: 02/09/2023]
Abstract
BACKGROUND Clear cell renal cell carcinoma (ccRCC), with its hallmark phenotype of high cytosolic lipid content, is considered a metabolic cancer. Despite the implication of this lipid-rich phenotype in ccRCC tumorigenesis, the roles and regulators of de novo lipid synthesis (DNL) in ccRCC remain largely unexplained. METHODS Our bioinformatic screening focused on ccRCC-lipid phenotypes identified glutathione peroxidase 8 (GPX8), as a clinically relevant upstream regulator of DNL. GPX8 genetic silencing was performed with CRISPR-Cas9 or shRNA in ccRCC cell lines to dissect its roles. Untargeted metabolomics, RNA-seq analyses, and other biochemical assays (e.g., lipid droplets staining, fatty acid uptake, cell proliferation, xenograft, etc.) were carried out to investigate the GPX8's involvement in lipid metabolism and tumorigenesis in ccRCC. The lipid metabolic function of GPX8 and its downstream were also measured by isotope-tracing-based DNL flux measurement. RESULTS GPX8 knockout or downregulation substantially reduced lipid droplet levels (independent of lipid uptake), fatty acid de novo synthesis, triglyceride esterification in vitro, and tumor growth in vivo. The downstream regulator was identified as nicotinamide N-methyltransferase (NNMT): its knockdown phenocopied, and its expression rescued, GPX8 silencing both in vitro and in vivo. Mechanically, GPX8 regulated NNMT via IL6-STAT3 signaling, and blocking this axis suppressed ccRCC survival by activating AMPK. Notably, neither the GPX8-NNMT axis nor the DNL flux was affected by the von Hippel Lindau (VHL) status, the conventional regulator of ccRCC high lipid content. CONCLUSIONS Taken together, our findings unravel the roles of the VHL-independent GPX8-NNMT axis in ccRCC lipid metabolism as related to the phenotypes and growth of ccRCC, which may be targeted for therapeutic purposes.
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Affiliation(s)
- Tin Tin Manh Nguyen
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Thi Ha Nguyen
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Han Sun Kim
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Thien T. P. Dao
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Yechan Moon
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Munjun Seo
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Sunmi Kang
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Van-Hieu Mai
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea ,grid.444808.40000 0001 2037 434XMolecular Biology Department, School of Medicine, Vietnam National University, Ho Chi Minh City, 70000 Vietnam
| | - Yong Jin An
- grid.31501.360000 0004 0470 5905Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826 Republic of Korea
| | - Cho-Rok Jung
- grid.249967.70000 0004 0636 3099Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea ,grid.412786.e0000 0004 1791 8264Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, 34113 Republic of Korea
| | - Jin-Mo Kim
- Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Sunghyouk Park
- Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea.
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5
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Thurgood LA, Best OG, Rowland A, Lower KM, Brooks DA, Kuss BJ. Lipid uptake in chronic lymphocytic leukemia. Exp Hematol 2021; 106:58-67. [PMID: 34896245 DOI: 10.1016/j.exphem.2021.12.193] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/02/2021] [Accepted: 12/05/2021] [Indexed: 11/19/2022]
Abstract
Many cancers rely on glucose as an energy source, but it is becoming increasingly apparent that some cancers use alternate substrates to fuel their proliferation. Chronic lymphocytic leukaemia (CLL) is one such cancer. Through the use of flow cytometry and confocal microscopy, low levels of glucose uptake were observed in the OSU-CLL and HG3 CLL cell lines relative to highly glucose-avid Raji cells (Burkitt's lymphoma). Glucose uptake in CLL cells correlated with low expression of the GLUT1 and GLUT3 receptors. In contrast, both CLL cell lines and primary CLL cells, but not healthy B cells, were found to rapidly internalise medium- and long-chain, but not short-chain, fatty acids (FAs). Differential FA uptake was also observed in primary cells taken from patients with unmutated immunoglobulin heavy variable chain usage (IGHV) compared with patients with mutated IGHV. Delipidation of serum in the culture medium slowed the proliferation and significantly reduced the viability of OSU-CLL and HG3 cells, effects that were partially reversed by supplementation with a chemically defined lipid concentrate. These observations highlight the potential importance of FAs in the pathogenesis of CLL and raise the possibility that targeting FA utilisation may represent a novel therapeutic and prognostic approach in this disease.
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Affiliation(s)
- Lauren A Thurgood
- Molecular Medicine and Genetics, College of Medicine and Public Health, Flinders University, Bedford Park, Australia.
| | - Oliver G Best
- Molecular Medicine and Genetics, College of Medicine and Public Health, Flinders University, Bedford Park, Australia
| | - Ashley Rowland
- Molecular Medicine and Genetics, College of Medicine and Public Health, Flinders University, Bedford Park, Australia
| | - Karen M Lower
- Molecular Medicine and Genetics, College of Medicine and Public Health, Flinders University, Bedford Park, Australia
| | - Doug A Brooks
- Cancer Research Institute, University of South Australia, Adelaide, Australia
| | - Bryone J Kuss
- Molecular Medicine and Genetics, College of Medicine and Public Health, Flinders University, Bedford Park, Australia
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6
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Inhibition of Orbivirus Replication by Fluvastatin and Identification of the Key Elements of the Mevalonate Pathway Involved. Viruses 2021; 13:v13081437. [PMID: 34452303 PMCID: PMC8402872 DOI: 10.3390/v13081437] [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: 06/30/2021] [Revised: 07/16/2021] [Accepted: 07/20/2021] [Indexed: 01/21/2023] Open
Abstract
Statin derivatives can inhibit the replication of a range of viruses, including hepatitis C virus (HCV, Hepacivirus), dengue virus (Flavivirus), African swine fever virus (Asfarviridae) and poliovirus (Picornaviridae). We assess the antiviral effect of fluvastatin in cells infected with orbiviruses (bluetongue virus (BTV) and Great Island virus (GIV)). The synthesis of orbivirus outer-capsid protein VP2 (detected by confocal immunofluorescence imaging) was used to assess levels of virus replication, showing a reduction in fluvastatin-treated cells. A reduction in virus titres of ~1.7 log (98%) in fluvastatin-treated cells was detected by a plaque assay. We have previously identified a fourth non-structural protein (NS4) of BTV and GIV, showing that it interacts with lipid droplets in infected cells. Fluvastatin, which inhibits 3-hydroxy 3-methyl glutaryl CoA reductase in the mevalonic acid pathway, disrupts these NS4 interactions. These findings highlight the role of the lipid pathways in orbivirus replication and suggest a greater role for the membrane-enveloped orbivirus particles than previously recognised. Chemical intermediates of the mevalonic acid pathway were used to assess their potential to rescue orbivirus replication. Pre-treatment of IFNAR(−/−) mice with fluvastatin promoted their survival upon challenge with live BTV, although only limited protection was observed.
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7
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Savino AM, Fernandes SI, Olivares O, Zemlyansky A, Cousins A, Markert EK, Barel S, Geron I, Frishman L, Birger Y, Eckert C, Tumanov S, MacKay G, Kamphorst JJ, Herzyk P, Fernández-García J, Abramovich I, Mor I, Bardini M, Barin E, Janaki-Raman S, Cross JR, Kharas MG, Gottlieb E, Izraeli S, Halsey C. Metabolic adaptation of acute lymphoblastic leukemia to the central nervous system microenvironment is dependent on Stearoyl CoA desaturase. NATURE CANCER 2020; 1:998-1009. [PMID: 33479702 PMCID: PMC7116605 DOI: 10.1038/s43018-020-00115-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/14/2020] [Indexed: 02/07/2023]
Abstract
Metabolic reprogramming is a key hallmark of cancer, but less is known about metabolic plasticity of the same tumor at different sites. Here, we investigated the metabolic adaptation of leukemia in two different microenvironments, the bone marrow and the central nervous system (CNS). We identified a metabolic signature of fatty-acid synthesis in CNS leukemia, highlighting Stearoyl-CoA desaturase (SCD1) as a key player. In vivo SCD1 overexpression increases CNS disease, whilst genetic or pharmacological inhibition of SCD1 decreases CNS load. Overall, we demonstrated that leukemic cells dynamically rewire metabolic pathways to suit local conditions and that targeting these adaptations can be exploited therapeutically.
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Affiliation(s)
- Angela Maria Savino
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sheba Medical Center, Ramat Gan, Israel
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sara Isabel Fernandes
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Orianne Olivares
- Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Anna Zemlyansky
- Schneider Children's Medical Center of Israel, Petach Tiqva, Israel
| | - Antony Cousins
- Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Elke K Markert
- Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Cancer Research UK Beatson Institute, Glasgow, UK
| | - Shani Barel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sheba Medical Center, Ramat Gan, Israel
| | - Ifat Geron
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sheba Medical Center, Ramat Gan, Israel
| | - Liron Frishman
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sheba Medical Center, Ramat Gan, Israel
| | - Yehudit Birger
- Sheba Medical Center, Ramat Gan, Israel
- Schneider Children's Medical Center of Israel, Petach Tiqva, Israel
| | | | | | | | - Jurre J Kamphorst
- Cancer Research UK Beatson Institute, Glasgow, UK
- Rheos Medicines, Cambridge, MA, USA
| | - Pawel Herzyk
- Glasgow Polyomics, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Institute of Molecular, Cell and Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Jonatan Fernández-García
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ifat Abramovich
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Inbal Mor
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Michela Bardini
- Centro Ricerca Tettamanti, Fondazione MBBM, Universita degli Studi di Milano-Bicocca, Monza, Italy
| | - Ersilia Barin
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sudha Janaki-Raman
- Donald B. and Catherine C. Marron Cancer Metabolism Center, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Justin R Cross
- Donald B. and Catherine C. Marron Cancer Metabolism Center, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Michael G Kharas
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Eyal Gottlieb
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
| | - Shai Izraeli
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
- Sheba Medical Center, Ramat Gan, Israel.
- Schneider Children's Medical Center of Israel, Petach Tiqva, Israel.
- Beckman Research Institute, City of Hope, Duarte, CA, USA.
| | - Christina Halsey
- Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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8
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Dolui AK, Vijayaraj P. A solvent-free delipidation method for functional validation of lipases. 3 Biotech 2020; 10:343. [PMID: 32714738 DOI: 10.1007/s13205-020-02338-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 07/12/2020] [Indexed: 10/23/2022] Open
Abstract
Extracting protein in its active form is critical for its functional characterization, and lipid removal is an essential step in the protein extraction process for further downstream applications. In the present study, we revisited the delipidation protocol and developed a rapid, solvent-free delipidation method using activated silica. The delipidated samples showed improved optical clarity and a significant reduction of endogenous lipids. The functional integrity of the lipases present in the delipidated sample was validated by in vitro enzyme assay using physiological substrate which includes neutral lipid as well as phospholipid. The accessibility of active site of the extracted enzymes was demonstrated by activity-based protein profiling (ABPP), a functional chemoproteomic approach. Detection of serine hydrolases using ABPP probe labeling was enhanced upon delipidation. Further, the total polyphenol content was significantly reduced, which helps to enhance the protein enrichment and small-molecule inhibitor screening by ABPP. Collectively, these results suggest that the present solvent-free delipidation approach is efficient and highly compatible with the functional characterization of the enzymes, particularly lipid hydrolases.
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9
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Yin X, Fang B, Zhang X, Li J, Li Y. Salt‐assisted acetonitrile extraction and HPLC‐QTOF‐MS/MS detection for residues of multiple classes of pesticides in human serum samples. J Sep Sci 2020; 43:3534-3545. [DOI: 10.1002/jssc.201901223] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 06/20/2020] [Accepted: 06/24/2020] [Indexed: 12/23/2022]
Affiliation(s)
- Xue‐feng Yin
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional EngineeringChina Agricultural University Beijing P. R. China
| | - Bing Fang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional EngineeringChina Agricultural University Beijing P. R. China
| | - Xiao‐xu Zhang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional EngineeringChina Agricultural University Beijing P. R. China
| | - Jin‐wang Li
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional EngineeringChina Agricultural University Beijing P. R. China
| | - Yi‐xuan Li
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional EngineeringChina Agricultural University Beijing P. R. China
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10
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Pires IS, Palmer AF. Tangential flow filtration of haptoglobin. Biotechnol Prog 2020; 36:e3010. [PMID: 32348635 DOI: 10.1002/btpr.3010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/07/2020] [Accepted: 04/21/2020] [Indexed: 12/14/2022]
Abstract
Haptoglobin (Hp) is a plasma glycoprotein that scavenges cell-free hemoglobin (Hb). Hp has various potential therapeutic applications, but it has been mainly studied for treatment of acute hemolytic conditions that can arise from situations such as massive blood transfusion, infusion of stored red blood cells, severe burns, trauma, sepsis, radiation injury, and others. Therefore, Hp may also be beneficial during chronic hemolytic disease states such as hereditary spherocytosis, nocturnal hemoglobinuria, sickle-cell anemia, and malaria. Various methods have been developed to purify Hp from plasma or plasma fractions. However, none of these methods have exploited the large molecular weight (MW) range distribution of Hp polymers to easily isolate Hp from other plasma proteins. The present study used tangential flow filtration (TFF) to isolate polymeric Hp from plasma proteins using human Fraction IV (FIV) as the starting material. After removal of insoluble material from a suspension of FIV paste, the protein mixture was clarified on a 0.2 μm hollow fiber (HF) TFF filter. The clarified protein solution was then bracketed based on protein MW using HF filters with MW cut-offs (MWCOs) of 750, 500, and 100 kDa. Using untreated FIV, the Hp purity of the main bracket was ~75% with a total Hb binding capacity (HbBC) yield of 1.2 g starting from 500 g of FIV paste. However, pretreatment of FIV with fumed silica to remove lipoproteins increased Hp purity to >95% with a HbBC yield of 1.7 g per 500 g of FIV. Taken together this study provides a novel and scalable method to purify Hp from plasma or plasma fractions.
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Affiliation(s)
- Ivan S Pires
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Andre F Palmer
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, USA
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11
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Brovkovych V, Aldrich A, Li N, Atilla-Gokcumen GE, Frasor J. Removal of Serum Lipids and Lipid-Derived Metabolites to Investigate Breast Cancer Cell Biology. Proteomics 2019; 19:e1800370. [PMID: 30919589 DOI: 10.1002/pmic.201800370] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/18/2019] [Indexed: 11/10/2022]
Abstract
The use of cultured cells has been instrumental in studying biochemical, molecular, and cellular processes. The composition of serum that cells are maintained in can have a profound impact on important cellular checkpoints. Cell growth and apoptosis are analyzed in an estrogen receptor positive breast cancer cell line in the presence of serum that have been treated to remove steroids or lipids, as well-described in the literature. It is shown that maintaining cells in the presence of charcoal-dextran-treated serum causes reduced growth rate, which can be reversed by the addition of estradiol. Silica-treated-serum also slows down cell growth and induces apoptosis. In order to investigate the role of lipids in these phenotypes, the levels of a wide range of lipids in different sera are investigated. It is shown that silica-treatment significantly depletes phosphatidylcholines and cholesterol. It is also shown that lipogenesis is stimulated when cells are cultured with silica-treated-serum and this is reversed by the addition of exogenous lipids, which also restores growth rate and apoptosis. The results show that cultured cells are sensitive to different serum, most likely due to the differences in levels of structural and signaling metabolites present in their growth environment.
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Affiliation(s)
- Viktor Brovkovych
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Alyssa Aldrich
- Department of Chemistry, University at Buffalo, Buffalo, NY, 14260, USA
| | - Nasi Li
- Department of Chemistry, University at Buffalo, Buffalo, NY, 14260, USA
| | | | - Jonna Frasor
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, 60612, USA
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Onder S, Tacal O, Lockridge O. Delipidation of Plasma Has Minimal Effects on Human Butyrylcholinesterase. Front Pharmacol 2018; 9:117. [PMID: 29497381 PMCID: PMC5818420 DOI: 10.3389/fphar.2018.00117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/31/2018] [Indexed: 12/01/2022] Open
Abstract
Human butyrylcholinesterase (BChE) is purified in large quantities from Cohn fraction IV-4 to use for protection against the toxicity of chemical warfare agents. Small scale preliminary experiments use outdated plasma from the American Red Cross as the starting material for purifying BChE (P06276). Many of the volunteer donor plasma samples are turbid with fat, the donor having eaten fatty food before the blood draw. The turbid fat interferes with enzyme assays performed in the spectrophotometer and with column chromatography. Our goal was to find a method to remove fat from plasma without loss of BChE activity. Satisfactory delipidation was achieved by adding a solution of 10% dextran sulfate and calcium chloride to fatty plasma, followed by centrifugation, and filtration through a 0.8 μm filter. Treatment with Aerosil also delipidated fatty plasma, but was accompanied by loss of 50% of the plasma volume. BChE activity and the BChE isozyme pattern on nondenaturing gel electrophoresis were unaffected by delipidation. BChE in delipidated plasma was efficiently captured by immobilized monoclonal antibodies B2 18-5 and mAb2. The immunopurified BChE was released from antibody binding with acid and visualized as a highly enriched, denatured BChE preparation by SDS gel electrophoresis. In conclusion, delipidation with dextran sulfate/CaCl2 preserves BChE activity and the tetramer structure of BChE.
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Affiliation(s)
- Seda Onder
- Department of Biochemistry, School of Pharmacy, Hacettepe University, Ankara, Turkey
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE, United States
| | - Ozden Tacal
- Department of Biochemistry, School of Pharmacy, Hacettepe University, Ankara, Turkey
| | - Oksana Lockridge
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE, United States
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Liu X, Abbott NL. Lateral Transport of Solutes in Microfluidic Channels Using Electrochemically Generated Gradients in Redox-Active Surfactants. Anal Chem 2011; 83:3033-41. [DOI: 10.1021/ac103058g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaoyang Liu
- Department of Chemical and Biological Engineering, University of Wisconsin, 1415 Engineering Drive, Madison, Wisconsin 53706-1691, United States
| | - Nicholas L. Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin, 1415 Engineering Drive, Madison, Wisconsin 53706-1691, United States
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14
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Bae HD, Kitaguchi K, Horio F, Murai A. Higher incorporation of heterologous chicken immunoglobulin Y compared with homologous quail immunoglobulin Y into egg yolks of Japanese quail (Coturnix japonica). Poult Sci 2009; 88:1703-11. [PMID: 19590086 DOI: 10.3382/ps.2008-00238] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In avian species, blood IgY is selectively incorporated into the yolks of maturing oocytes, although the precise mechanism is poorly understood. Our previous study showed that 22% of i.v.-injected heterologous chicken IgY (cIgY) was incorporated into egg yolks of Japanese quail (Coturnix japonica). However, it is not known whether homologous quail IgY (qIgY) can be more efficiently incorporated into quail egg yolks than cIgY. Therefore, we compared the uptakes of qIgY and cIgY i.v. administered into quail egg yolks and further characterized the uptakes of these 2 antibodies into quail ovarian follicles. Quail IgY and cIgY purified from the blood of the respective bird were labeled with digoxigenin, and their uptakes into quail egg yolks were determined by ELISA. Unexpectedly, total incorporation of the injected qIgY was only one-third of that of cIgY, although much more qIgY was left in blood compared with cIgY, suggesting that qIgY is the less preferable antibody as a transport ligand into quail egg yolks. On the other hand, deposition of the qIgY into heart, lung, liver, spleen, kidney, and ovarian follicular membrane was markedly higher than that of cIgY. Amino acid sequence analysis of 3 peptides derived from the trypsin-digested qIgY heavy chain revealed low homology between qIgY and cIgY. In conclusion, our results show that heterologous cIgY is more efficiently incorporated into quail egg yolks than homologous qIgY, possibly due to a distinctive antibody transport system existing in oocytes. The present results also may provide a new strategy for delivering useful proteinaceous substances into egg yolks in an attempt to produce designer eggs.
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Affiliation(s)
- H-D Bae
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, 464-8601 Nagoya, Japan
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15
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Kramsky JA, Manning EJB, Collins MT. Protein G binding to enriched serum immunoglobulin from nondomestic hoofstock species. J Vet Diagn Invest 2003; 15:253-61. [PMID: 12735347 DOI: 10.1177/104063870301500306] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Quick and cost-effective serologic assays, such as those based on enzyme-linked immunosorbent assay (ELISA) technology, are useful for screening animal populations for infectious diseases. Recombinant protein G is described as an almost universal ELISA conjugate for the detection of antibodies from a wide range of animal species. However, there is limited data documenting the ability of protein G to bind immunoglobulin (Ig) from many captive and free-ranging nondomestic hoofstock (Order Artiodactyla, e.g., elk, antelope, bison). Protein G binding to Ig from 11 species within this taxonomic order (addax, antelope, bison, bontebok, elk, impala, kudu/nyala, muntjac, oryx, sheep, and white-tailed deer) and 2 control species (bovine and chicken) was assessed. A serum Ig enrichment protocol, using high-performance liquid chromatography (HPLC), was optimized in bovids (Bos taurus) and then applied to the other study species. Binding assays were performed by adding protein G to microtiter wells coated with titrated dilutions of enriched artiodactyl Ig. Optical densities were measured and binding curves generated. Differences in protein G binding were observed, both within and among species, as well as within taxonomic families. Significant intraspecies binding variation was observed for 7 species tested (antelope, oryx, sheep, muntjac, impala, bontebok, and addax). No statistically significant intraspecies differences in protein G binding were found for Ig from bison, elk, kudu/nyala, white-tailed deer, plus control species (cattle and chicken). Binding of protein G to Ig from impala, muntjac, and elk was statistically different from the positive control (cattle), with muntjac binding curves statistically comparable with the negative control (chicken). For the other 7 species tested, binding curves illustrated the ability of protein G to bind Ig as well as, or better than, the positive control. These findings expand the list of animal species whose Ig is capable of being detected using recombinant protein G, with the caveat that protein G does not bind Ig uniformly in closely related species. It is concluded that recombinant protein G conjugates may serve as useful reagents for serodiagnosis by ELISA in nondomestic hoofstock, although different assay interpretation algorithms and assay protocols may need to be developed on a per species basis for maximum diagnostic effectiveness.
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Affiliation(s)
- Joely A Kramsky
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
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16
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Artiss J, Morgan B, Zak B. Total parenteral nutrition turbidity and clearing of serum for assay purposes. Microchem J 2002. [DOI: 10.1016/s0026-265x(02)00033-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Smialowski-Fléter S, Moulin A, Perrier J, Puigserver A. Myristyl and palmityl acylation of pI 5.1 carboxylesterase from porcine intestine and liver. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:1109-17. [PMID: 11856341 DOI: 10.1046/j.0014-2956.2001.02704.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Immunoblotting analyses revealed the presence of carboxylesterase in the porcine small intestine, liver, submaxillary and parotid glands, kidney cortex, lungs and cerebral cortex. In the intestinal mucosa, the pI 5.1 enzyme was detected in several subcellular fractions including the microvillar fraction. Both fatty monoacylated and diacylated monomeric (F1), trimeric (F3) and tetrameric (F4) forms of the intestinal protein were purified here for the first time by performing hydrophobic chromatography and gel filtration. The molecular mass of these three enzymatic forms was estimated to be 60, 180 and 240 kDa, respectively, based on size-exclusion chromatography and SDS/PAGE analysis. The existence of a covalent attachment linking palmitate and myristate to porcine intestinal carboxylesterase (PICE), which was suggested by the results of gas-liquid chromatography (GLC) experiments in which the fatty acids resulting from alkali treatment of the protein forms were isolated, was confirmed here by the fact that [3H]palmitic and [3H]myristic acids were incorporated into porcine enterocytes and hepatocytes in cell primary cultures. Besides these two main fatty acids, the presence of oleic, stearic, and arachidonic acids was also detected by GLC and further confirmed by performing radioactivity counts on the 3H-labelled PICE forms after an immunoprecipitation procedure using specific polyclonal antibodies, followed by a SDS/PAGE separation step. Unlike the F1 and F4 forms, which were both myristoylated and palmitoylated, the F3 form was only palmitoylated. The monomeric, trimeric and tetrameric forms of PICE were all able to hydrolyse short chain fatty acids containing glycerides, as well as phorbol esters. The broad specificity of fatty acylated carboxylesterase is discussed in terms of its possible involvement in the metabolism of ester-containing xenobiotics and signal transduction.
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Affiliation(s)
- Sylvie Smialowski-Fléter
- Institut Méditerranéen de Recherche en Nutrition, UMR-INRA, Faculté des Sciences et Techniques de St-Jérôme, Marseille, France
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Guder W, da Fonseca-Wollheim F, Heil W, Schmitt YM, Töpfer G, Wisser H, Zawta B. The Haemolytic, Icteric and Lipemic Sample Recommendations Regarding their Recognition and Prevention of Clinically Relevant Interferences. Recommendations of the Working Group on Preanalytical Variables of the German Society for Clinical Chemistry and the German Society for Laboratory Medicine. ACTA ACUST UNITED AC 2000. [DOI: 10.1515/labm.2000.24.8.357] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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20
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Morgan B, Artiss J, Zak B. Enzymatic clearing of lipemic serum for the determination of serum calcium. Microchem J 1991. [DOI: 10.1016/0026-265x(91)90070-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Henderson LO, Hazlehurst JS, Taylor L, Hannon WH. Preparation of lyophilized human serum based reference materials with graded levels of apolipoproteins A-I and B. Clin Biochem 1988; 21:219-23. [PMID: 3136957 DOI: 10.1016/s0009-9120(88)80004-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Surveys of national and international laboratories indicate that among-laboratory and between-laboratory sources of variance account for the majority of variability in laboratories measuring apolipoproteins A-I and B. These sources of variance are amenable to correction through the use of common quality control and reference materials. We utilized proven techniques employing ethyl alcohol and acetate buffer to precipitate either apolipoprotein A-I rich or apolipoprotein B rich fractions that were blended with whole or delipidated serum producing five pilot-sized pools containing graded levels of apolipoproteins. After lyophilization the pools were tested and each pool contained levels of analytes similar to frozen serum and contained varied amounts of apolipoproteins A-I and B. Temporal and accelerated thermal stability testing demonstrated stability of the analytes in the pools with time (three years) and temperature (up to 56 degrees C). This technology provides a preparative procedure for apolipoprotein reference materials over the extended range needed in clinical applications.
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Affiliation(s)
- L O Henderson
- Division of Environmental Health Laboratory Sciences, Centers for Disease Control, Atlanta, Georgia 30333
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22
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Flückiger R, Woodtli T, Berger W. Evaluation of the fructosamine test for the measurement of plasma protein glycation. Diabetologia 1987; 30:648-52. [PMID: 3653563 DOI: 10.1007/bf00277323] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Repeated estimation of plasma protein glycation by the fructosamine assay gave more variable results than expected from analytical variability (coefficient of variation approximately 2%). Fructosamine results obtained on plasma samples drawn at different times of the day differed by up to 1 mmol/l, corresponding to a coefficient of variation of greater than 10%. As a consequence, the information concerning averaged glycaemia of a fructosamine determination is subject to an uncertainty of 7.8 mmol/l. Fructosamine concentrations were linearly related to the protein concentration. Correction for the protein concentration decreased this variability; however, factors other than protein concentration, such as lipid content, also influence results of fructosamine determinations.
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Affiliation(s)
- R Flückiger
- Department of Research, University Clinics, Kantonsspital, Basel, Switzerland
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23
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Artiss JD, Zak B. Problems with measurements caused by high concentrations of serum solids. Crit Rev Clin Lab Sci 1987; 25:19-41. [PMID: 3301210 DOI: 10.3109/10408368709105876] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
There have been numerous reports of spectrophotometric and volume problems caused by elevated levels of lipids in blood. The offending lipids, primarily triglycerides, not only cause turbidity leading to optical aberrations when added to analytical reagents, but also result in short-sampling errors leading to the measurement of inaccurate volumes of sample. Numerous methods have been developed to clear the lipemia, including ultracentrifugation organic solvent extraction, chemical precipitation and, most recently, enzymic hydrolysis. Although the latter procedures eliminate the optical problems, they do not deal with the volume dilution error created by the triglycerides. In turn, corrective mathematics have been developed to compensate for the inaccurate pipetting caused by the elevated lipids in a sample; however, these empirical calculations are not truly accurate at high concentrations of total lipids. This monograph will describe the problems caused by the presence of elevated lipids and the means available for treating them.
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24
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McGowan MW, Artiss JD, Zak B. Description of analytical problems arising from elevated serum solids. Anal Biochem 1984; 142:239-51. [PMID: 6528966 DOI: 10.1016/0003-2697(84)90460-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
There has always been a problem with the collection of data and interpretation of the results obtained from any biological fluid in which the solids content was increased to a great extent. Of these solids, the triglycerides of the lipids may cause a plasma (serum) to vary in appearance from opalescent to milky. This condition of the specimen and the concomitant turbidity upon its addition to reagents creates the well-documented optical aberrations of spectrophotometric measurements. In addition, the lipids, in conjunction with the proteins, can act as diluents when they are elevated, thereby decreasing what might be termed the residual true plasma volume. Thus the water content of an aliquot sampled for a particular analytical procedure is diminished, and by that means a situation is created in which a short sample is drawn. This dilution effect by the solids results in a lowering of the assay values obtained for the measured constituents of such a serum sample. An associated phenomenon of high concentrations of solids, especially proteins, is the increase in viscosity of a specimen, a condition that also causes an error of short sampling when certain peristaltic pumping devices are used. This review considers several aspects of problems encountered when dealing with a number of circumstances that are critical to the measurement of analytes in severely hyperlipemic and/or hyperproteinemic specimens. These include the problems of short sampling; the potential amelioration of the problem by corrective mathematics, extraction of the lipids, or ultracentrifugation of the true plasma from the lipids; the important need to include most analytes into our considerations; the difference in reference base values for the calculation of concentrations of lipids of serum versus other analytes; the concept of the use of ratios when the reference base values differ, numerator analyte from denominator analyte; and the problems of using serum blanks when necessary corrective action for the solids volume is neglected. Thus, in the final analysis, problems with underestimated volumes of samples used for many spectrophotometric determinations are considered here along with the other difficulties encountered when the need to measure analytes in serums with extremely high solids content presents.
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