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Exchange-mode glutamine transport across CNS cell membranes. Neuropharmacology 2019; 161:107560. [PMID: 30853601 DOI: 10.1016/j.neuropharm.2019.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/28/2019] [Accepted: 03/02/2019] [Indexed: 12/18/2022]
Abstract
CNS cell membranes possess four transporters capable of exchanging Lglutamine (Gln) for other amino acids: the large neutral amino acid (LNAA) transporters LAT1 and LAT2, the hybrid basic amino acid (L-arginine (Arg), L-leucine (Leu)/LNAA transporter y+LAT2, and the L-alanine/L-serine/L-cysteine transporter 2 (ASCT2). LAT1/LAT2 and y+LAT2 are present in astrocytes, neurons and the blood brain barrier (BBB) - forming cerebral vascular endothelial cells (CVEC), while the location of ASCT2 in the individual cell types is a matter of debate. In the healthy brain, contribution of the exchangers to Gln shuttling from astrocytes to neurons and thus their role in controlling the conversion of Gln to the amino acid neurotransmitters l-glutamate (Glu) and γ-aminobutyric acid (GABA) and Gln flux across the BBB appears negligible as compared to the system A and system N uniporters. Insofar, except for the contribution of LAT1 to the maintenance of Gln homeostasis in the interstitial fluid (ISF), no well-defined CNS-specific function has been established for either of the three transporters in the healthy brain. The Gln-accepting amino acid exchangers appear to gain significance under conditions of excessive brain Gln load (glutaminosis). Excess Gln efflux across the BBB enhances influx into the brain of L-tryptophan (Trp). Excess of Trp is responsible for overloading the brain with neuroactive compounds: serotonin, kynurenic acid, quinolinic acid and/or oxindole, which contribute to neurotransmission imbalance accompanying hyperammonemia. In turn, alterations of y+LAT2-mediated Gln/Arg exchange and Arg uptake in astrocyte, modulate astrocytic nitric oxide synthesis and oxidative/nitrosative stress in ammonia-overexposed brain. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Sekine A, Fukuwatari T. Acute liver failure increases kynurenic acid production in rat brain via changes in tryptophan metabolism in the periphery. Neurosci Lett 2019; 701:14-19. [PMID: 30738081 DOI: 10.1016/j.neulet.2019.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 02/03/2019] [Accepted: 02/04/2019] [Indexed: 12/20/2022]
Abstract
The tryptophan metabolite, kynurenic acid (KYNA), is a preferential antagonist of the α7 nicotinic acetylcholine receptor and N-methyl-d-aspartic acid receptor at endogenous brain concentrations. Recent studies have suggested that increased brain KYNA levels are involved in psychiatric disorders such as schizophrenia and depression. Most of the brain kynurenine (KYN), the KYNA precursor, comes from the periphery, and the liver has a central role in the peripheral tryptophan metabolism. In this study, the effect of acute liver failure (ALF) on brain KYNA production and on the peripheral tryptophan metabolism was investigated in rats. ALF was induced by administration of the hepatotoxin, thioacetamide (TAA). Brain KYNA levels were increased by TAA-induced ALF, and these increases were consistent with KYN levels in the brain, serum and liver. These results suggest that the ALF-induced increase in serum KYN contributes to the increase in brain KYNA via elevated KYN uptake within the brain. This increase in serum KYN level can be caused by the changes in tryptophan-2,3-dioxygenase activity in the liver and the immune-related activation of indoleamine-2,3-dioxygenase in extrahepatic tissues. These findings suggest that hepatic dysfunction may contribute to neurological and psychiatric diseases associated with increased KYNA levels.
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Affiliation(s)
- Airi Sekine
- Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga, 522-8533, Japan
| | - Tsutomu Fukuwatari
- Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga, 522-8533, Japan.
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Altered tryptophan catabolite concentrations in major depressive disorder and associated changes in hippocampal subfield volumes. Psychoneuroendocrinology 2018; 95:8-17. [PMID: 29787958 DOI: 10.1016/j.psyneuen.2018.05.019] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 05/14/2018] [Accepted: 05/14/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND Tryptophan depletion is a well-replicated biological finding in Major Depressive Disorder (MDD). The kynurenine pathway (KP) and its rate-limiting tryptophan degrading enzyme, indolamine 2,3 dioxygenase (IDO), have been implicated in the pathogenesis of depression. IDO expression is driven by inflammatory cytokines, providing a putative link between inflammation and neuropathology. This study examined circulating concentrations of C-reactive protein (CRP), plasma tryptophan, kynurenine (KYN), kynurenic acid (KYNA) and quinolinic acid (QUIN) and whole blood mRNA expression of IDO in patients with major depressive disorder (MDD) compared with healthy controls (HC). METHODS A diagnosis of major depression was made according to DSM-IV. Depression severity was assessed using the Hamilton depression (HAM-D) rating scale. 74 MDD patients, 39 with a first presentation of MDD (fpMDD) and 35 with chronic or recurrent episodes (rMDD), and 37 HC were recruited to the study. Whole blood and plasma samples were collected. Expression of markers in whole blood were measured by PCR, circulating CRP by ELISA and KP metabolites by LC-MS/MS. Hippocampal cornu ammonis (CA) and subiculum volumes were determined by MRI and calculated using FreeSurfer. RESULTS Tryptophan concentrations were significantly reduced in MDD compared to HC. There was a positive correlation between QUIN and both CRP concentrations and whole blood IDO1 in MDD. KYNA concentrations were reduced in MDD patients presenting with a first episode (fpMDD) compared to those presenting with recurrent depression (rMDD) and HC. By contrast QUIN concentrations were elevated in rMDD compared to fpMDD and HC. KYNA/QUIN was reduced in MDD and rMDD but not fpMDD compared to HC. Hippocampal subfield volumes were smaller in MDD patients than HC for CA1 (left only), CA2/3 (left and right) and CA4 (right only). CRP and CA1 volumes were negatively correlated bilaterally in MDD patients. KYNA and subiculum volume were positively correlated bilaterally. DISCUSSION This study found evidence of KP metabolism imbalance in MDD patients in addition to tryptophan reduction and mild immune activation. Relationships between CRP and KYNA with some hippocampal subfield volumes in MDD patients suggest that this inflammatory signature may be associated with reduced hippocampal subfield volumes in depression.
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Fan Y, Liu X. Alterations in Expression and Function of ABC Family Transporters at Blood-Brain Barrier under Liver Failure and Their Clinical Significances. Pharmaceutics 2018; 10:pharmaceutics10030102. [PMID: 30041501 PMCID: PMC6161250 DOI: 10.3390/pharmaceutics10030102] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/20/2018] [Accepted: 07/21/2018] [Indexed: 02/07/2023] Open
Abstract
Liver failure is often associated with hepatic encephalopathy, due to dyshomeostasis of the central nervous system (CNS). Under physiological conditions, the CNS homeostasis is precisely regulated by the blood-brain barrier (BBB). The BBB consists of brain microvessel endothelial cells connected with a junctional complex by the adherens junctions and tight junctions. Its main function is to maintain brain homoeostasis via limiting the entry of drugs/toxins to brain. The brain microvessel endothelial cells are characterized by minimal pinocytotic activity, absent fenestrations, and highly expressions of ATP-binding cassette (ABC) family transporters (such as P-glycoprotein, breast cancer resistance protein and multidrug resistance-associated proteins). These ABC transporters prevent brain from toxin accumulation by pumping toxins out of brain. Accumulating evidences demonstrates that liver failure diseases altered the expression and function of ABC transporters at The BBB, indicating that the alterations subsequently affect drugs’ brain distribution and CNS activity/neurotoxicity. ABC transporters also mediate the transport of endogenous substrates across the BBB, inferring that ABC transporters are also implicated in some physiological processes and the development of hepatic encephalopathy. This paper focuses on the alteration in the BBB permeability, the expression and function of ABC transporters at the BBB under liver failure status and their clinical significances.
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Affiliation(s)
- Yilin Fan
- Center of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009, China.
| | - Xiaodong Liu
- Center of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009, China.
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Jiang X, Xu L, Tang L, Liu F, Chen Z, Zhang J, Chen L, Pang C, Yu X. Role of the indoleamine-2,3-dioxygenase/kynurenine pathway of tryptophan metabolism in behavioral alterations in a hepatic encephalopathy rat model. J Neuroinflammation 2018; 15:3. [PMID: 29301550 PMCID: PMC5753541 DOI: 10.1186/s12974-017-1037-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 12/12/2017] [Indexed: 01/08/2023] Open
Abstract
Background This study aims to explore the role of indoleamine-2,3-dioxygenase (IDO)/kynurenine (KYN) pathway of tryptophan (TRY) metabolism in behavioral alterations observed in hepatic encephalopathy (HE) rats. Methods Expression levels of proinflammatory cytokines were tested by QT-PCR and ELISA, levels of IDOs were tested by QT-PCR and Western blot, and levels of 5-hydroxytryptamine (5-HT), KYN, TRY, 3-hydroxykynurenine (3-HK), and kynurenic acid (KA) in different brain regions were estimated using HPLC. Effects of the IDO direct inhibitor 1-methyl-l-tryptophan (1-MT) on cognitive, anxiety, and depressive-like behavior were evaluated in bile duct ligation (BDL) rats. Results Increased serum TNF-α, IL-1β, and IL-6 levels were shown in rats 7 days after BDL, and these increases were observed earlier than those in the brain, indicating peripheral immune activation may result in central upregulation of proinflammatory cytokines. Moreover, BDL rats showed a progressive decline in memory formation, as well as anxiety and depressive-like behavior. Further study revealed that IDO expression increased after BDL, accompanied by a decrease of 5-HT and an increase of KYN, as well as abnormal expression of 3-HK and KA. The above results affected by BDL surgery were reversed by IDO inhibitor 1-MT treatment. Conclusion Taken together, these findings indicate that (1) behavioral impairment in BDL rats is correlated with proinflammatory cytokines; (2) TRY pathway of KYN metabolism, activated by inflammation, may play an important role in HE development; and (3) 1-MT may serve as a therapeutic agent for HE. Electronic supplementary material The online version of this article (10.1186/s12974-017-1037-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xi Jiang
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China. .,Mingzhou Hospital, Zhejiang University, Hangzhou, Zhejiang Province, 315000, China.
| | - Lexing Xu
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China
| | - Lin Tang
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China
| | - Fuhe Liu
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China
| | - Ziwei Chen
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China
| | - Jiajia Zhang
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China
| | - Lei Chen
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China
| | - Cong Pang
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, 223001, China.
| | - Xuefeng Yu
- Department of Pharmacy, Zhejiang Pharmaceutical College, Ningbo, Zhejiang Province, 315000, China.
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Han X, Min M, Wang J, Bao Z, Fan H, Li X, Adelusi TI, Zhou X, Yin X. Quantitative profiling of neurotransmitter abnormalities in brain, cerebrospinal fluid, and serum of experimental diabetic encephalopathy male rat. J Neurosci Res 2017; 96:138-150. [DOI: 10.1002/jnr.24098] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/14/2017] [Accepted: 05/16/2017] [Indexed: 01/16/2023]
Affiliation(s)
- Xiaowen Han
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University; Xuzhou China
| | - Mengjun Min
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University; Xuzhou China
| | - Juan Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University; Xuzhou China
| | - Zejun Bao
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University; Xuzhou China
| | - Hongbin Fan
- Department of Neurology; Affiliated Hospital of Xuzhou Medical University; Xuzhou China
| | - Xinyu Li
- Department of Neurology; Affiliated Hospital of Xuzhou Medical University; Xuzhou China
| | - Temitope Isaac Adelusi
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University; Xuzhou China
| | - Xueyan Zhou
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University; Xuzhou China
| | - Xiaoxing Yin
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University; Xuzhou China
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Lahdou I, Sadeghi M, Oweira H, Fusch G, Daniel V, Mehrabi A, Jung GE, Elhadedy H, Schmidt J, Sandra-Petrescu F, Iancu M, Opelz G, Terness P, Schefold JC. Increased serum levels of quinolinic acid indicate enhanced severity of hepatic dysfunction in patients with liver cirrhosis. Hum Immunol 2013; 74:60-6. [DOI: 10.1016/j.humimm.2012.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/28/2012] [Accepted: 09/10/2012] [Indexed: 01/29/2023]
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Holt DE, Washabau RJ, Djali S, Dayrell-Hart B, Drobatz KJ, Heyes MP, Robinson MB. Cerebrospinal fluid glutamine, tryptophan, and tryptophan metabolite concentrations in dogs with portosystemic shunts. Am J Vet Res 2002; 63:1167-71. [PMID: 12171172 DOI: 10.2460/ajvr.2002.63.1167] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether glutamine (GLN), tryptophan (TRP), and tryptophan metabolite concentrations are higher in cerebralspinal fluid (CSF) dogs with naturally occurring portosystemic shunts (PSS), compared with control dogs. ANIMALS 11 dogs with confirmed PSS and 12 control dogs fed low- and high-protein diets. PROCEDURE Cerebrospinal fluid and blood samples were collected from all dogs. Serum and CSF concentrations of GLN, alanine, serine, TRP, 5-hydroxyindoleacetic acid (5-HIAA), and quinolinic acid (QUIN) were measured. RESULTS Cerebrospinal fluid concentrations of GLN, TRP, and 5-HIAA were significantly higher in PSS dogs, compared with control dogs fed high- or low-protein diets. Cerebrospinal fluid QUIN concentration was significantly higher in PSS dogs, compared with control dogs fed the low-protein diet. Serum QUIN concentration was significantly lower in PSS dogs, compared with control dogs fed either high- or low-protein diets. CONCLUSIONS AND CLINICAL RELEVANCE An increase in CNS GLN concentration is associated with high CSF concentrations of TRP and TRP metabolites in dogs with PSS. High CSF 5-HIAA concentrations indicate an increased flux of TRP through the CNS serotonin metabolic pathway, whereas high CSF QUIN concentrations indicate an increased metabolism of TRP through the indolamine-2,3-dioxygenase pathway. The high CSF QUIN concentrations in the face of low serum QUIN concentrations in dogs with PSS indicates that QUIN production from TRP is occurring in the CNS. High concentrations of QUIN and other TRP metabolites in the CNS may contribute to neurologic abnormalities found in dogs with PSS and hepatic encephalopathy.
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Affiliation(s)
- David E Holt
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104, USA
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Abstract
In just under 20 years the kynurenine family of compounds has developed from a group of obscure metabolites of the essential amino acid tryptophan into a source of intensive research, with postulated roles for quinolinic acid in neurodegenerative disorders, most especially the AIDS-dementia complex and Huntington's disease. One of the kynurenines, kynurenic acid, has become a standard tool for use in the identification of glutamate-releasing synapses, and has been used as the parent for several groups of compounds now being developed as drugs for the treatment of epilepsy and stroke. The kynurenines represent a major success in translating a basic discovery into a source of clinical understanding and therapeutic application, with around 3000 papers published on quinolinic acid or kynurenic acid since the discovery of their effects in 1981 and 1982. This review concentrates on some of the recent work most directly relevant to the understanding and applications of kynurenines in medicine.
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Affiliation(s)
- T W Stone
- Institute of Biomedical and Life Sciences, University West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
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Morrison PF, Morishige GM, Beagles KE, Heyes MP. Quinolinic acid is extruded from the brain by a probenecid-sensitive carrier system: a quantitative analysis. J Neurochem 1999; 72:2135-44. [PMID: 10217295 DOI: 10.1046/j.1471-4159.1999.0722135.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although the neurotoxic tryptophan-kynurenine pathway metabolite quinolinic acid originates in brain by both local de novo synthesis and entry from blood, its concentrations in brain parenchyma, extracellular fluid, and CSF are normally below blood values. In the present study, an intraperitoneal injection of probenecid (400 mg/kg), an established inhibitor of acid metabolite transport in brain, into gerbils, increased quinolinic acid concentrations in striatal homogenates, CSF, serum, and homogenates of kidney and liver. Direct administration of probenecid (10 mM) into the brain compartment via an in vivo microdialysis probe implanted into the striatum also caused a progressive elevation in both quinolinic acid and homovanillic acid concentrations in the extracellular fluid compartment but was without effect on serum quinolinic acid levels. A model of microdialysis transport showed that the elevations in extracellular fluid quinolinic acid and homovanillic acid levels following intrastriatal application are consistent with probenecid block of a microvascular acid transport mechanism. We conclude that quinolinic acid in brain is maintained at concentrations below blood levels largely by active extrusion via a probenecid-sensitive carrier system.
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Affiliation(s)
- P F Morrison
- Bioengineering and Physical Science Program, Office of Research Services, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-1262, USA
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Moroni F, Carpenedo R, Mannaioni G, Galli A, Chiarugi A, Carlà V, Moneti G. Studies on the pharmacological properties of oxindole (2-hydroxyindole) and 5-hydroxyindole: are they involved in hepatic encephalopathy? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 420:57-73. [PMID: 9286426 DOI: 10.1007/978-1-4615-5945-0_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- F Moroni
- Department of Pharmacology, University of Florence, Firenze, Italy
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Bengtsson F, Bergqvist P. Neuropsychiatric implications of brain tryptophan perturbations appearing in hepatic encephalopathy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 398:387-95. [PMID: 8906294 DOI: 10.1007/978-1-4613-0381-7_60] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- F Bengtsson
- Department of Clinical Pharmacology, Lund University Hospital, Sweden
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Bergqvist PB, Heyes MP, Bengtsson F. Is quinolinic acid involved in the pathogenesis of hepatic encephalopathy? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 398:397-405. [PMID: 8906295 DOI: 10.1007/978-1-4613-0381-7_61] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- P B Bergqvist
- Department of Clinical Pharmacology, Lund University Hospital, Sweden
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