TY - GEN A1 - Naser, Eyad A1 - Kadow, Stephanie A1 - Schumacher, Fabian A1 - Mohamed, Zainelabdeen H. A1 - Kappe, Christian A1 - Hessler, Gabriele A1 - Pollmeier, Barbara A1 - Kleuser, Burkhard A1 - Arenz, Christoph A1 - Becker, Katrin Anne A1 - Gulbins, Erich A1 - Carpinteiro, Alexander T1 - Characterization of the small molecule ARC39 BT - a direct and specific inhibitor of acid sphingomyelinase in vitro[S] T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Inhibition of acid sphingomyelinase (ASM), a lysosomal enzyme that catalyzes the hydrolysis of sphingomyelin into ceramide and phosphorylcholine, may serve as an investigational tool or a therapeutic intervention to control many diseases. Specific ASM inhibitors are currently not sufficiently characterized. Here, we found that 1-aminodecylidene bis-phosphonic acid (ARC39) specifically and efficiently (>90%) inhibits both lysosomal and secretory ASM in vitro. Results from investigating sphingomyelin phosphodiesterase 1 (SMPD1/Smpd1) mRNA and ASM protein levels suggested that ARC39 directly inhibits ASM's catalytic activity in cultured cells, a mechanism that differs from that of functional inhibitors of ASM. We further provide evidence that ARC39 dose- and time-dependently inhibits lysosomal ASM in intact cells, and we show that ARC39 also reduces platelet- and ASM-promoted adhesion of tumor cells. The observed toxicity of ARC39 is low at concentrations relevant for ASM inhibition in vitro, and it does not strongly alter the lysosomal compartment or induce phospholipidosis in vitro. When applied intraperitoneally in vivo, even subtoxic high doses administered short-term induced sphingomyelin accumulation only locally in the peritoneal lavage without significant accumulation in plasma, liver, spleen, or brain. These findings require further investigation with other possible chemical modifications. In conclusion, our results indicate that ARC39 potently and selectively inhibits ASM in vitro and highlight the need for developing compounds that can reach tissue concentrations sufficient for ASM inhibition in vivo. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1407 KW - sphingolipids KW - sphingomyelin KW - cerami-des KW - lipid metabolism KW - enzymology KW - lysosome KW - lysosomal hydrolases KW - acid ceramidase KW - bisphosphonates KW - functional inhibitors of acid sphin-gomyelinase KW - 1-aminodecylidene bis-phosphonic acid Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516635 SN - 1866-8372 IS - 6 ER - TY - GEN A1 - Beckmann, Nadine A1 - Becker, Katrin Anne A1 - Kadow, Stephanie A1 - Schumacher, Fabian A1 - Kramer, Melanie A1 - Kühn, Claudine A1 - Schulz-Schaeffer, Walter J. A1 - Edwards, Michael J. A1 - Kleuser, Burkhard A1 - Gulbins, Erich A1 - Carpinteiro, Alexander T1 - Acid sphingomyelinase deficiency ameliorates Farber disease T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Farber disease is a rare lysosomal storage disorder resulting from acid ceramidase deficiency and subsequent ceramide accumulation. No treatments for Farber disease are clinically available, and affected patients have a severely shortened lifespan. We have recently reported a novel acid ceramidase deficiency model that mirrors the human disease closely. Acid sphingomyelinase is the enzyme that generates ceramide upstream of acid ceramidase in the lysosomes. Using our acid ceramidase deficiency model, we tested if acid sphingomyelinase could be a potential novel therapeutic target for the treatment of Farber disease. A number of functional acid sphingomyelinase inhibitors are clinically available and have been used for decades to treat major depression. Using these as a therapeutic for Farber disease, thus, has the potential to improve central nervous symptoms of the disease as well, something all other treatment options for Farber disease can’t achieve so far. As a proof-of-concept study, we first cross-bred acid ceramidase deficient mice with acid sphingomyelinase deficient mice in order to prevent ceramide accumulation. Double-deficient mice had reduced ceramide accumulation, fewer disease manifestations, and prolonged survival. We next targeted acid sphingomyelinase pharmacologically, to test if these findings would translate to a setting with clinical applicability. Surprisingly, the treatment of acid ceramidase deficient mice with the acid sphingomyelinase inhibitor amitriptyline was toxic to acid ceramidase deficient mice and killed them within a few days of treatment. In conclusion, our study provides the first proof-of-concept that acid sphingomyelinase could be a potential new therapeutic target for Farber disease to reduce disease manifestations and prolong survival. However, we also identified previously unknown toxicity of the functional acid sphingomyelinase inhibitor amitriptyline in the context of Farber disease, strongly cautioning against the use of this substance class for Farber disease patients T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1087 KW - Farber disease KW - lysosomal storage disorders KW - acid ceramidase KW - acid sphingomyelinase KW - amitriptyline Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-441282 SN - 1866-8372 IS - 1087 ER - TY - JOUR A1 - Naser, Eyad A1 - Kadow, Stephanie A1 - Schumacher, Fabian A1 - Mohamed, Zainelabdeen H. A1 - Kappe, Christian A1 - Hessler, Gabriele A1 - Pollmeier, Barbara A1 - Kleuser, Burkhard A1 - Arenz, Christoph A1 - Becker, Katrin Anne A1 - Gulbins, Erich A1 - Carpinteiro, Alexander T1 - Characterization of the small molecule ARC39 BT - a direct and specific inhibitor of acid sphingomyelinase in vitro[S] JF - Journal of Lipid Research N2 - Inhibition of acid sphingomyelinase (ASM), a lysosomal enzyme that catalyzes the hydrolysis of sphingomyelin into ceramide and phosphorylcholine, may serve as an investigational tool or a therapeutic intervention to control many diseases. Specific ASM inhibitors are currently not sufficiently characterized. Here, we found that 1-aminodecylidene bis-phosphonic acid (ARC39) specifically and efficiently (>90%) inhibits both lysosomal and secretory ASM in vitro. Results from investigating sphingomyelin phosphodiesterase 1 (SMPD1/Smpd1) mRNA and ASM protein levels suggested that ARC39 directly inhibits ASM's catalytic activity in cultured cells, a mechanism that differs from that of functional inhibitors of ASM. We further provide evidence that ARC39 dose- and time-dependently inhibits lysosomal ASM in intact cells, and we show that ARC39 also reduces platelet- and ASM-promoted adhesion of tumor cells. The observed toxicity of ARC39 is low at concentrations relevant for ASM inhibition in vitro, and it does not strongly alter the lysosomal compartment or induce phospholipidosis in vitro. When applied intraperitoneally in vivo, even subtoxic high doses administered short-term induced sphingomyelin accumulation only locally in the peritoneal lavage without significant accumulation in plasma, liver, spleen, or brain. These findings require further investigation with other possible chemical modifications. In conclusion, our results indicate that ARC39 potently and selectively inhibits ASM in vitro and highlight the need for developing compounds that can reach tissue concentrations sufficient for ASM inhibition in vivo. KW - sphingolipids KW - sphingomyelin KW - cerami-des KW - lipid metabolism KW - enzymology KW - lysosome KW - lysosomal hydrolases KW - acid ceramidase KW - bisphosphonates KW - functional inhibitors of acid sphin-gomyelinase KW - 1-aminodecylidene bis-phosphonic acid Y1 - 2021 U6 - https://doi.org/10.1194/jlr.RA120000682 SN - 1539-7262 SN - 0022-2275 VL - 61 IS - 6 SP - 896 EP - 910 PB - American Society for Biochemistry and Molecular Biology CY - Bethesda ER - TY - JOUR A1 - Beckmann, Nadine A1 - Kadow, Stephanie A1 - Schumacher, Fabian A1 - Goethert, Joachim R. A1 - Kesper, Stefanie A1 - Draeger, Annette A1 - Schulz-Schaeffer, Walter J. A1 - Wang, Jiang A1 - Becker, Jan U. A1 - Kramer, Melanie A1 - Kuehn, Claudine A1 - Kleuser, Burkhard A1 - Becker, Katrin Anne A1 - Gulbins, Erich A1 - Carpinteiro, Alexander T1 - Pathological manifestations of Farber disease in a new mouse model JF - Biological chemistry N2 - Farber disease (FD) is a rare lysosomal storage disorder resulting from acid ceramidase deficiency and subsequent ceramide accumulation. No treatments are clinically available and affected patients have a severely shortened lifespan. Due to the low incidence, the pathogenesis of FD is still poorly understood. Here, we report a novel acid ceramidase mutant mouse model that enables the study of pathogenic mechanisms of FD and ceramide accumulation. Asah1(tmEx1) mice were generated by deletion of the acid ceramidase signal peptide sequence. The effects on lysosomal targeting and activity of the enzyme were assessed. Ceramide and sphingomyelin levels were quantified by liquid chromatography tandem-mass spectrometry (LC-MS/MS) and disease manifestations in several organ systems were analyzed by histology and biochemistry. We show that deletion of the signal peptide sequence disrupts lysosomal targeting and enzyme activity, resulting in ceramide and sphingomyelin accumulation. The affected mice fail to thrive and die early. Histiocytic infiltrations were observed in many tissues, as well as lung inflammation, liver fibrosis, muscular disease manifestations and mild kidney injury. Our new mouse model mirrors human FD and thus offers further insights into the pathogenesis of this disease. In the future, it may also facilitate the development of urgently needed therapies. KW - acid ceramidase KW - ceramide KW - Farber disease KW - lysosomal storage disorders Y1 - 2018 U6 - https://doi.org/10.1515/hsz-2018-0170 SN - 1431-6730 SN - 1437-4315 VL - 399 IS - 10 SP - 1183 EP - 1202 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Neuber, Corinna A1 - Schumacher, Fabian A1 - Gulbins, Erich A1 - Kleuser, Burkhard T1 - Method to simultaneously determine the sphingosine 1-phosphate breakdown product (2E)-hexadecenal and its fatty acid derivatives using isotope-dilution HPLC-electrospray ionization-quadrupole/time-of-flight mass spectrometry JF - Analytical chemistry N2 - Sphingosine 1-phosphate (S1P), a bioactive lipid involved in various physiological processes, can be irreversibly degraded by the membrane-bound S1P lyase (S1PL) yielding (2E)-hexadecenal and phosphoethanolamine. It is discussed that (2E)-hexadecenal is further oxidized to (2E)-hexadecenoic acid by the long-chain fatty aldehyde dehydrogenase ALDH3A2 (also known as FALDH) prior to activation via coupling to coenzyme A (CoA). Inhibition or defects in these enzymes, S1PL or FALDH, result in severe immunological disorders or the Sjogren-Larsson syndrome, respectively. Hence, it is of enormous importance to simultaneously determine the S1P breakdown product (2E)-hexadecenal and its fatty acid metabolites in biological samples. However, no method is available so far. Here, we present a sensitive and selective isotope-dilution high performance liquid chromatographyelectrospray ionizationquadrupole/time-of-flight mass spectrometry method for simultaneous quantification of (2E)-hexadecenal and its fatty acid metabolites following derivatization with 2-diphenylacetyl-1,3-indandione-1-hydrazone and 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide. Optimized conditions for sample derivatization, chromatographic separation, and MS/MS detection are presented as well as an extensive method validation. Finally, our method was successfully applied to biological samples. We found that (2E)-hexadecenal is almost quantitatively oxidized to (2E)-hexadecenoic acid, that is further activated as verified by cotreatment of HepG2 cell lysates with (2E)-hexadecenal and the acyl-CoA synthetase inhibitor triacsin C. Moreover, incubations of cell lysates with deuterated (2E)-hexadecenal revealed that no hexadecanoic acid is formed from the aldehyde. Thus, our method provides new insights into the sphingolipid metabolism and will be useful to investigate diseases known for abnormalities in long-chain fatty acid metabolism, e.g., the Sjogren-Larsson syndrome, in more detail. Y1 - 2014 U6 - https://doi.org/10.1021/ac501677y SN - 0003-2700 SN - 1520-6882 VL - 86 IS - 18 SP - 9065 EP - 9073 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Neuber, Corinna A1 - Schumacher, Fabian A1 - Gulbins, Erich A1 - Kleuser, Burkhard T1 - Mass Spectrometric Determination of Fatty Aldehydes Exemplified by Monitoring the Oxidative Degradation of (2E)-Hexadecenal in HepG2 Cell Lysates JF - Lipidomics N2 - Within the last few decades, liquid chromatography-mass spectrometry (LC-MS) has become a preferred method for manifold issues in analytical biosciences, given its high selectivity and sensitivity. However, the analysis of fatty aldehydes, which are important components of cell metabolism, remains challenging. Usually, chemical derivatization prior to MS detection is required to enhance ionization efficiency. In this regard, the coupling of fatty aldehydes to hydrazines like 2,4-dinitrophenylhydrazine (DNPH) is a common approach. Additionally, hydrazones readily react with fatty aldehydes to form stable derivatives, which can be easily separated using high-performance liquid chromatography (HPLC) and subsequently detected by MS. Here, we exemplarily present the quantification of the long-chain fatty aldehyde (2E)-hexadecenal, a break-down product of the bioactive lipid sphingosine 1-phosphate (S1P), after derivatization with 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) via isotope-dilution HPLC-electrospray ionization-quadrupole/time-of-flight (ESI-QTOF) MS. Moreover, we show that the addition of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC hydrochloride) as a coupling agent allows for simultaneous determination of fatty aldehydes and fatty acids as DAIH derivatives. Taking advantage of this, we describe in detail how to monitor the degradation of (2E)-hexadecenal and the concurrent formation of its oxidation product (2E)-hexadecenoic acid in lysates of human hepatoblastoma (HepG2) cells within this chapter. KW - (2E)-hexadecenal KW - (2E)-hexadecenoic acid KW - Sphingosine 1-phosphate KW - Derivatization KW - DAIH KW - EDC KW - Isotope-dilution KW - HPLC-ESI-QTOF Y1 - 2017 SN - 978-1-4939-6946-3 SN - 978-1-4939-6944-9 U6 - https://doi.org/10.1007/978-1-4939-6946-3_10 SN - 0893-2336 SN - 1940-6045 VL - 125 SP - 147 EP - 158 PB - Humana Press CY - Totowa ER - TY - JOUR A1 - Fayyaz, Susann A1 - Japtok, Lukasz A1 - Schumacher, Fabian A1 - Wigger, Dominik A1 - Schulz, Tim Julius A1 - Haubold, Kathrin A1 - Gulbins, Erich A1 - Völler, Heinz A1 - Kleuser, Burkhard T1 - Lysophosphatidic acid inhibits insulin signaling in primary rat hepatocytes via the LPA(3) receptor subtype and is increased in obesity JF - Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology N2 - Background/Aims: Obesity is a main risk factor for the development of hepatic insulin resistance and it is accompanied by adipocyte hypertrophy and an elevated expression of different adipokines such as autotaxin (ATX). ATX converts lysophosphatidylcholine to lysophosphatidic acid (LPA) and acts as the main producer of extracellular LPA. This bioactive lipid regulates a broad range of physiological and pathological responses by activation of LPA receptors (LPA1-6). Methods: The activation of phosphatidylinositide 3-kinases (PI3K) signaling (Akt and GSK-3ß) was analyzed via western blotting in primary rat hepatocytes. Incorporation of glucose into glycogen was measured by using radio labeled glucose. Real-time PCR analysis and pharmacological modulation of LPA receptors were performed. Human plasma LPA levels of obese (BMI > 30, n = 18) and normal weight individuals (BMI 18.5-25, n = 14) were analyzed by liquid chromatography tandem-mass spectrometry (LC-MS/MS). Results: Pretreatment of primary hepatocytes with LPA resulted in an inhibition of insulin-mediated Gck expression, PI3K activation and glycogen synthesis. Pharmacological approaches revealed that the LPA3-receptor subtype is responsible for the inhibitory effect of LPA on insulin signaling. Moreover, human plasma LPA concentrations (16: 0 LPA) of obese participants (BMI > 30) are significantly elevated in comparison to normal weight individuals (BMI 18.5-25). Conclusion: LPA is able to interrupt insulin signaling in primary rat hepatocytes via the LPA3 receptor subtype. Moreover, the bioactive lipid LPA (16: 0) is increased in obesity. KW - Lysophosphatidic acid KW - Insulin signaling KW - Adipose tissue KW - Autotaxin KW - Hepatic insulin resistance KW - LPA(3) receptor subtype Y1 - 2017 U6 - https://doi.org/10.1159/000480470 SN - 1015-8987 SN - 1421-9778 VL - 43 SP - 445 EP - 456 PB - Karger CY - Basel ER - TY - GEN A1 - Wigger, Dominik A1 - Gulbins, Erich A1 - Kleuser, Burkhard A1 - Schumacher, Fabian T1 - Monitoring the Sphingolipid de novo Synthesis by Stable-Isotope Labeling and Liquid Chromatography-Mass Spectrometry T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - Sphingolipids are a class of lipids that share a sphingoid base backbone. They exert various effects in eukaryotes, ranging from structural roles in plasma membranes to cellular signaling. De novo sphingolipid synthesis takes place in the endoplasmic reticulum (ER), where the condensation of the activated C₁₆ fatty acid palmitoyl-CoA and the amino acid L-serine is catalyzed by serine palmitoyltransferase (SPT). The product, 3-ketosphinganine, is then converted into more complex sphingolipids by additional ER-bound enzymes, resulting in the formation of ceramides. Since sphingolipid homeostasis is crucial to numerous cellular functions, improved assessment of sphingolipid metabolism will be key to better understanding several human diseases. To date, no assay exists capable of monitoring de novo synthesis sphingolipid in its entirety. Here, we have established a cell-free assay utilizing rat liver microsomes containing all the enzymes necessary for bottom-up synthesis of ceramides. Following lipid extraction, we were able to track the different intermediates of the sphingolipid metabolism pathway, namely 3-ketosphinganine, sphinganine, dihydroceramide, and ceramide. This was achieved by chromatographic separation of sphingolipid metabolites followed by detection of their accurate mass and characteristic fragmentations through high-resolution mass spectrometry and tandem-mass spectrometry. We were able to distinguish, unequivocally, between de novo synthesized sphingolipids and intrinsic species, inevitably present in the microsome preparations, through the addition of stable isotope-labeled palmitate-d₃ and L-serine-d₃. To the best of our knowledge, this is the first demonstration of a method monitoring the entirety of ER-associated sphingolipid biosynthesis. Proof-of-concept data was provided by modulating the levels of supplied cofactors (e.g., NADPH) or the addition of specific enzyme inhibitors (e.g., fumonisin B₁). The presented microsomal assay may serve as a useful tool for monitoring alterations in sphingolipid de novo synthesis in cells or tissues. Additionally, our methodology may be used for metabolism studies of atypical substrates – naturally occurring or chemically tailored – as well as novel inhibitors of enzymes involved in sphingolipid de novo synthesis. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 800 KW - sphingolipid de novo synthesis KW - serine palmitoyltransferase KW - mass spectrometry KW - stable-isotope labeling KW - ceramides Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-441158 SN - 1866-8372 IS - 800 ER - TY - JOUR A1 - Beckmann, Nadine A1 - Becker, Katrin Anne A1 - Kadow, Stephanie A1 - Schumacher, Fabian A1 - Kramer, Melanie A1 - Kuehn, Claudine A1 - Schulz-Schaeffer, Walter J. A1 - Edwards, Michael J. A1 - Kleuser, Burkhard A1 - Gulbins, Erich A1 - Carpinteiro, Alexander T1 - Acid Sphingomyelinase Deficiency Ameliorates Farber Disease JF - International journal of molecular sciences N2 - Farber disease is a rare lysosomal storage disorder resulting from acid ceramidase deficiency and subsequent ceramide accumulation. No treatments for Farber disease are clinically available, and affected patients have a severely shortened lifespan. We have recently reported a novel acid ceramidase deficiency model that mirrors the human disease closely. Acid sphingomyelinase is the enzyme that generates ceramide upstream of acid ceramidase in the lysosomes. Using our acid ceramidase deficiency model, we tested if acid sphingomyelinase could be a potential novel therapeutic target for the treatment of Farber disease. A number of functional acid sphingomyelinase inhibitors are clinically available and have been used for decades to treat major depression. Using these as a therapeutic for Farber disease, thus, has the potential to improve central nervous symptoms of the disease as well, something all other treatment options for Farber disease can’t achieve so far. As a proof-of-concept study, we first cross-bred acid ceramidase deficient mice with acid sphingomyelinase deficient mice in order to prevent ceramide accumulation. Double-deficient mice had reduced ceramide accumulation, fewer disease manifestations, and prolonged survival. We next targeted acid sphingomyelinase pharmacologically, to test if these findings would translate to a setting with clinical applicability. Surprisingly, the treatment of acid ceramidase deficient mice with the acid sphingomyelinase inhibitor amitriptyline was toxic to acid ceramidase deficient mice and killed them within a few days of treatment. In conclusion, our study provides the first proof-of-concept that acid sphingomyelinase could be a potential new therapeutic target for Farber disease to reduce disease manifestations and prolong survival. However, we also identified previously unknown toxicity of the functional acid sphingomyelinase inhibitor amitriptyline in the context of Farber disease, strongly cautioning against the use of this substance class for Farber disease patients. KW - Farber disease KW - lysosomal storage disorders KW - acid ceramidase KW - acid sphingomyelinase KW - amitriptyline Y1 - 2019 U6 - https://doi.org/10.3390/ijms20246253 SN - 1422-0067 VL - 20 IS - 24 PB - MDPI CY - Basel ER - TY - JOUR A1 - Morris, Mackenzie C. A1 - Kassam, Farzaan A1 - Bercz, Aron A1 - Beckmann, Nadine A1 - Schumacher, Fabian A1 - Gulbins, Erich A1 - Makley, Amy T. A1 - Goodman, Michael D. T1 - The Role of Chemoprophylactic Agents in Modulating Platelet Aggregability After Traumatic Brain Injury JF - Journal of surgical research N2 - Background: The pathophysiology behind the subacute but persistent hypercoagulable state after traumatic brain injury (TBI) is poorly understood but contributes to morbidity induced by venous thromboembolism. Because platelets and their microvesicles have been hypothesized to play a role in post-traumatic hypercoagulability, administration of commonly used agents may ameliorate this coagulability. We hypothesized that utilization of aspirin, ketorolac, amitriptyline, unfractionated heparin, or enoxaparin would modulate the platelet aggregation response after TBI. Methods: Concussive TBI was induced by weight drop. Mice were then randomized to receive aspirin, ketorolac, amitriptyline, heparin, enoxaparin, or saline control at 2 and 8 h after TBI. Mice were sacrificed at 6 or 24 h after injury to determine coagulability by rotational thromboelastometry (ROTEM), platelet function testing with impedance aggregometry, and microvesicle enumeration. Platelet sphingolipid metabolites were analyzed by mass spectrometry. Results: ROTEM demonstrated increased platelet contribution to maximum clot firmness at 6 h after TBI in mice that received aspirin or amitriptyline, but this did not persist at 24 h. By contrast, adenosine diphosphate- and arachidonic acid-induced platelet aggregation at 6 h was significantly lower in mice receiving ketorolac, aspirin, and amitriptyline compared with mice receiving saline at 6 h after injury and only arachidonic acid-initiated platelet aggregation was decreased by aspirin at 24 h. There were no differences in microvesicle production at either time point. Platelet sphingosine-1-phosphate levels were decreased at 6 h in the group receiving amitriptyline and increased at 24 h along with platelet ceramide levels at 24 h in the amitriptyline group. Conclusion: After TBI, amitriptyline decreased platelet aggregability and increased contribution to clot in a manner similar to aspirin. The amitriptyline effects on platelet function and sphingolipid metabolites may represent a possible role of the acid sphingomyelinase in the hypercoagulability observed after injury. In addition, inhibition of platelet reactivity may be an underappreciated benefit of low molecular weight heparins, such as enoxaparin. (C) 2019 Elsevier Inc. All rights reserved. KW - Trauma KW - Traumatic brain injury KW - Venous thromboembolism KW - Chemoprophylaxis KW - Sphingolipids Y1 - 2019 U6 - https://doi.org/10.1016/j.jss.2019.06.022 SN - 0022-4804 SN - 1095-8673 VL - 244 SP - 1 EP - 8 PB - Elsevier CY - San Diego ER -