The role of human and microbial metabolites of triptophane in severe diseases and critical ill (review)

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Abstract

The growing interest to metabolites circulating in the blood is associated with the accumulation of factual material on the involvement of low-molecular compounds in the development of a number of serious diseases. This review reveals the effect of a whole class of chemical compounds — tryptophan metabolites — on various pathological processes. The following keywords were used to find the publications in the PubMed database for the last 10 years: names of natural indole compounds, methods for their detection, nosology of diseases and critical illness . The data are presented in sections, with the studies of tryptophan metabolites in a variety of disease groups, such as cancer, cardiovascular disease, kidney disease, bowel, mental disorders, atherosclerosis, etc. A particular attention is paid to the role of indole compounds that enter the systemic circulation as a result of microbial biotransformation of tryptophan, serotonin and other indole metabolites, which can be attributed to the “common metabolites” of humans and microbiota. The most interesting clinical studies are summarized in the tables and figures. A number of indole metabolites are considered as potential biomarkers. The authors of the review substantiate the metabolomic approach to the study of a number of oncological, septic, mental and other intractable diseases, which opens up new possibilities of influence on the pathological process by targeted regulation in the metabolome/microbiome system.

About the authors

M. L. Getsina

Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology

Email: nvbeloborodova@yandex.ru
ORCID iD: 0000-0001-7222-4140
SPIN-code: 1666-2899
Scopus Author ID: 6506928189

Cand. Sci. (Chem.)

Russian Federation, Moscow

E. A. Chernevskaya

Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology

Email: kate.chernevskaya@gmail.com
ORCID iD: 0000-0002-9316-8907
SPIN-code: 1141-7892

Cand. Sci. (Biol.)

Russian Federation, Moscow

N. V. Beloborodova

Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology

Author for correspondence.
Email: nvbeloborodova@yandex.ru
ORCID iD: 0000-0003-2328-1610
SPIN-code: 8739-0123

MD, Dr. Sci. (Med.)

Russian Federation, Moscow

References

  1. Wikoff WR, Anfora AT, Liu J, et al. Metabolomics analysis reveals large effects of gut microflora on mammalian blood metabolites. PNAS. 2009;106(10):3698–3703. doi: 10.1073/pnas.0812874106.
  2. Beloborodova NV, Olenin AY, Pautova AK. Metabolomic findings in sepsis as a damage of host-microbial metabolism integration. J Crit Care. 2018;43:246–255. doi: 10.1016/j.jcrc.2017.09.014.
  3. Cani PD, Van Hul M, Lefort C, et al. Microbial regulation of organismal energy homeostasis. Nat Metab. 2019;(1):34–46. doi: 10.1038/s42255-018-0017-4.
  4. Beloborodova NV, Sarshor YN, Bedova AY, et al. Involvement of aromatic metabolites in the pathogenesis of septic shock. Shock. 2018;50(3):273–279. doi: 10.1097/shk.0000000000001064.
  5. Palego L, Betti L, Rossi A, Giannaccini G. Tryptophan biochemistry: structural, nutritional, metabolic, and medical aspects in humans. J Amino Acids. 2016;2016:8952520. doi: 10.1155/2016/8952520.
  6. Beloborodova NV, Grechko AV, Olenin AYu. Metabolomic discovery of microbiota dysfunction as the cause of pathology. Open access peer-reviewed chapter. IntechOpen. 2019. doi: 10.5772/intechopen.87176.
  7. Keszthelyi D, Troost FJ, Masclee AA. Understanding the role of tryptophan and serotonin metabolism in gastrointestinal function. Neurogastroenterol Motil. 2009;21(12):1239–1249. doi: 10.1111/j.1365-2982.2009.01370.x.
  8. Humane Metabolom Data Base. Showing metabocard for L-tryptophan (HMDB0000929). The Metabolomics Innovation Centre; 2019 [cited 2005 Nov 16]. Available at: http://www.hmdb.ca/metabolites/HMDB0000929.
  9. Psychogios N, Hau DD, Peng J, et al. The human serum metabolome. PLoS One. 2011;6(2):e16957. doi: 10.1371/journal.pone.0016957.
  10. Fukushima T, Iizuka H, Yokota A, et al. Quantitative analyses of schizophrenia-associated metabolites in serum: serum D-lactate levels are negatively correlated with gamma-glutamylcysteine in medicated schizophrenia patients. PLoS One. 2014;9(7):e101652. doi: 10.1371/journal.pone.0101652.
  11. Rainesalo S, Keränen T, Palmio J, et al. Plasma and cerebrospinal fluid amino acids in epileptic patients. Neurochem Res. 2004;29(1):319–324. doi: 10.1023/b:nere.0000010461.34920.0c.
  12. Fujigaki S, Saito K, Takemura M, et al. Species differences in L-tryptophan-kynurenine pathway metabolism: quantification of anthranilic acid and its related enzymes. Arch Biochem Biophys. 1998;358(2):329–335. doi: 10.1006/abbi.1998.0861.
  13. Duranton F, Cohen G, De Smet R, et al. Normal and pathologic concentrations of uremic toxins. J Am Soc Nephrol. 2012;23:1–13. doi: 10.1681/ASN.2011121175.
  14. Carling RS, Oegg TJ, Allen KR, et al. Evaluation of whole blood serotonin and plasma and urine 5-hydroxyindole acetic acid in diagnosis of carcinoid disease. Ann Clin Biochem. 2002;39(6):577–582. doi: 10.1177/000456320203900605.
  15. Danaceau JP, Anderson GM, McMahon WM, Crouch DJ. A liquid chromatographic-tandem mass spectrometric method for the analysis of serotonin and related indoles in human whole blood. J Anal Toxicol. 2003;27(7):440–444. doi: 10.1093/jat/27.7.440.
  16. Alfredsson G, Wiesel FA. Monoamine metabolites and amino acids in serum from schizophrenic patients before and during sulpiride treatment. Psychopharmacology (Berl). 1989;99(3):322–327. doi: 10.1007/bf00445551.
  17. Козлов В.А., Демина Д.В. Триптофан и indoleamine-2,3-dioxygenase (IDO) в патогенезе иммунокомпрометированных заболеваний // Медицинская иммунология. — 2017. — Т.19. — №3. — С. 225–240. [Kozlov VA, Demina DV. Tryptophan and indoleamine-2,3-dioxygenase (IDO) in pathogenesis of immunosuppressive clinical conditions. Med Immunol. 2017;19(3):225–240. (In Russ).] doi: 10.15789/1563-0625-2017-3-225-240.
  18. Grohmann U, Fallarino F, Bianchi R, et al. A defect in tryptophan catabolism impairs tolerance in nonobese diabetic mice. J Exp Med. 2003;198(1):153–160. doi: 10.1084/jem.20030633.
  19. Grohmann U, Puccetti P. The coevolution of IDO1 and AhR in the emergence of regulatory T-cells in mammals. Front Immunol. 2015;6:58. doi: 10.3389/fimmu.2015.00058.
  20. Kennedy PJ, Cryan JF, Dinan TG, Clarke G. Kynurenine pathway metabolism and the microbiota-gut-brain axis. Neuropharmacology. 2017;112(Pt B):399–412. doi: 10.1016/j.neuropharm.2016.07.002.
  21. Козлов И.А., Клыпа Т.В., Рыбаков В.Ю., Матвеев Ю.Г. Первый опыт назначения серотонина адипината для коррекции сосудистой недостаточности у кардиохирургических больных // Вестник интенсивной терапии. — 2006. — №1. — С. 7–9. [Kozlov IA, Klypa TV, Fishakov VYu, Matveev YuG. The first experience of administration of serotonin adipinate for correction of vascular insufficiency in cardiosurgical patients. Ann Intensiv Care. 2006;(1):7–9. (In Russ).]
  22. Kaumann AJ, Levy FO. 5-Hydroxytryptamine receptors in the human cardiovascular system. Pharmacol Therapeut. 2006;111:674–706. doi: 10.1016/j.pharmthera.2005.12.004.
  23. Dahan D, Hien ТT, Tannenberg P, et al. MicroRNA-dependent control of serotonin-induced pulmonary arterial contraction. J Vasc Res. 2017;54(4):246–256. doi: 10.1159/000478013.
  24. Haynes RL, Frelinger AL, Giles EK, et al. High serum serotonin in sudden infant death syndrome. Proc Natl Acad Sci U S A. 2017;114(29):7695–7700. doi: 10.1073/pnas.1617374114.
  25. Schefold JC, Fritschi N, Fusch G, et al. Influence of core body temperature on Tryptophan metabolism, kynurenines, and estimated IDO activity in critically ill patientsreceiving target temperature management following cardiac arrest. Resuscitation. 2016;107:107–114. doi: 10.1016/j.resuscitation.2016.07.239.
  26. Cason CA, Dolan KT, Sharma G, et al. Plasma microbiome-modulated indole- and phenyl-derived metabolites associate with advanced atherosclerosis and postoperative outcomes. J Vasc Surg. 2018;68(5):1552–1562.e7. doi: 10.1016/j.jvs.2017.09.029.
  27. Ситкин С.И., Ткаченко Е.И., Вахитов Т.Я., и др. Метаболом сыворотки крови по данным газовой хроматографии — масс-спектрометрии (ГХ-МС) у пациентов с язвенным колитом и больных целиакией // Гастроэнтерология. — 2013. — №12. — С. 44–57. [Sitkin SI, Tkchenko EI, Vakhitov TJ, et al. Blood serum metabolism according to gas chromatography — mass spectrometry (GC-MS) in patients with ulcerative colitis and patients with celiac disease. Gastroenterology. 2013;(12):44–57. (In Russ).]
  28. Ilkhanizadeh B, Owji AA, Tavangar SM, et al. Spot urine 5-hydroxy indole acetic acid and acute appendicitis. Hepatogastroenterol. 2001;48(39):609–613.
  29. Jangjoo A, Varasteh AR, Mehrabi Bahar M, et al. Is urinary 5-hydroxyindoleacetic acid helpful for early diagnosis of acute appendicitis? Am J Emerg Med. 2012;30(4):540–544. doi: 10.1016/j.ajem.2011.01.027.
  30. Mentes O, Eryilmaz M, Harlak A, et al. The importance of urine 5-hydroxyindoleacetic acid levels in the early diagnosis of acute appendicitis. Am J Emerg Med. 2009;27(4):409–412. doi: 10.1016/j.ajem.2008.03.016
  31. Oruc MT, Kulah B, Ozozan O, et al. The value of 5-hydroxy indole acetic acid measurement in spot urine in diagnosis of acute appendicitis. East Afr Med J. 2004;81(1):40–41. doi: 10.4314/eamj.v81i1.8793.
  32. Bolandparvaz S, Vasei M, Owji AA, et al. Urinary 5-hydroxy indole acetic acid as a test for early diagnosis of acute appendicitis. Clin Biochem. 2004;37(11):985–989. doi: 10.1016/j.clinbiochem.2004.07.003.
  33. Rao A, Wilson M, Kennedy G, et al. Spot urinary 5-hydroxyindoleacetic acid is not an ideal diagnostic test for acute appendicitis. Am J Emerg Med. 2016;34(9):1750–1753. doi: 10.1016/j.ajem.2016.05.059.
  34. Tan B, Qiu Y, Zou X, et al. Metabonomics identifies serum metabolite markers of colorectal cancer. J Proteome Res. 2013;12(6):3000–3009. doi: 10.1021/pr400337b.
  35. Goedert JJ, Sampson JN, Moore SC, et al. Fecal metabolomics: assay performance and association with colorectal cancer. Carcinogenesis. 2014;35(9):2089–2096. doi: 10.1093/carcin/bgu131.
  36. Ardill JE, Armstrong L, Smye M, et al. Neuroendocrine tumours of the small bowel: interpretation of raised circulating chromogranin A, urinary 5 hydroxy indole acetic acid and neurokinin A. QJM. 2016;109(2):111–115. doi: 10.1093/qjmed/hcv095.
  37. Sinha R, Ahn J, Sampson JN, et al. Fecal microbiota, fecal metabolome, and colorectal cancer interrelations. PLoS One. 2016;11(3):e0152126. doi: 10.1371/journal.pone.0152126.
  38. Uchiyama K, Yagi N, Mizushima K, et al. Serum metabolomics analysis for early detection of colorectal Cancer. J Gastroenterol. 2017;52(6):677–694. doi: 10.1007/s00535-016-1261-6.
  39. Wei J, Xie G, Zhou Z, et al. Salivary metabolite signatures of oral cancer and leukoplakia. Int J Cancer. 2011;129:2207–2217. doi: 10.1002/ijc.25881.
  40. Englert JA, Rogers AJ. Metabolism, metabolomics, and nutritional support of patients with sepsis. Clin Chest Med. 2016;37(2):321–331. doi: 10.1016/j.ccm.2016.01.011.
  41. Meier MA, Ottiger M, Vegeli A, et al. Activation of the tryptophan/serotonin pathway is associated with severity and predicts outcomes in pneumonia: results of a long-term cohort study. Clin Chem Lab Med. 2017;55(7):1060–1069. doi: 10.1515/cclm-2016-0912.
  42. Orešič M, Posti JP, Kamstrup-Nielsen MH, et al. Human serum metabolites associatewith severity and patient outcomes in traumatic brain injury. EBioMedicine. 2016;12:118–126. doi: 10.1016/j.ebiom.2016.07.015.
  43. Marseglia L, D’Angelo G, Manti S, et al. Melatonin secretion is increased in children with severe traumatic brain injury. Int J Mol Sci. 2017;18(5). pii: E1053. doi: 10.3390/ijms18051053.
  44. Lorente L, Martín MM, Abreu-González P, et al. Serum melatonin levels in survivor and non-survivor patients with traumatic brain injury. BMC Neurology. 2017;17:138. doi: 10.1186/s12883-017-0922-2.
  45. Lorente L, Martín MM, Abreu-González P, et al. Serum melatonin levels are associated with mortality in severe septic patients. J Crit Care. 2015;30(4):860.e1–6. doi: 10.1016/j.jcrc.2015.03.023.
  46. Lin C, Chao H, Li Z, et al. Melatonin attenuates traumatic brain injury-induced inflammation: a possible role for mitophagy. J Pineal Res. 2016;61(2):177–186. doi: 10.1111/jpi.12337.
  47. Grima NA, Rajaratnam SM, Mansfield D, et al. Efficacy of melatonin for sleep disturbance following traumatic brain injury: a randomised controlled trial. BMC Med. 2018;16(1):8. doi: 10.1186/s12916-017-0995-1.
  48. Mistraletti G, Paroni R, Umbrello M, et al. Melatonin pharmacological blood levels increase total antioxidant capacity in critically ill patients. Int J Mol Sci. 2017;18(4). pii: E759. doi: 10.3390/ijms18040759.
  49. Сивков А.В., Синюхин В.Н., Арзуманов С.В., и др. Уремические токсины в крови больных с терминальной стадией почечной недостаточности при дисбиозе кишечника // Экспериментальная и клиническая урология. — 2014. — №2. — С. 94–97. [Sivkov AV, Sinyukhin VN, Arzumanov SV, et al. Uremic toxins in blood of end stage renal disease patients with dysbiosis of digestive tract. Experimental & clinical urology. 2014;(2):94–97. (In Russ).]
  50. Лукичёв Б.Г., Подгаецкая О.Ю., Карунная А.В., Румянцев А.Ш. Индоксил сульфат при хронической болезни почек // Нефрология. — 2014. — Т.18. — №1. — С. 25–32. [Lukichev BG, Karunnaya AV, Rumyantsev AS. Indoxyl sulphate at chronic kidney disease. Nephrology. 2014;18(1):25–32. (In Russ).]
  51. Lau WL, Savoj J, Nakata MB, Vaziri ND. Altered microbiome in chronic kidney disease: systemic effects of gut-derived uremic toxins. Clin Sci. 2018;132:509–522. doi: 10.1042/CS20171107.
  52. Huc T, Nowinski A, Drapala A, et al. Indole and indoxyl sulfate, gut bacteria metabolites of tryptophan, change arterial blood pressure via peripheral and central mechanisms in rats. Pharmacological Research. 2018;130:172–179.
  53. Etinger A, Kumar, Ackley W, et al. The effect of isohydric hemodialysis on the binding and removal of uremic retention solutes. Plos One. 2018;13(2):e0192770. doi: 10.1371/journal.pone.0192770.
  54. Chen JJ, Zhou CJ, Zheng P, et al. Differential urinary metabolites related with the severity of major depressive disorder. Behav Brain Res. 2017;332:280–287. doi: 10.1016/j.bbr.2017.06.012.
  55. Шилов Ю.Е., Безруков М.В. Кинуренины в патогенезе эндогенных психических заболеваний. Актуальные вопросы неврологии и психиатрии // Вестник РАМН. — 2013. — Т.68. — №1. — С. 35–41. [Shilov YE, Bezrukov MV. Kynurenines in pathogenesis of endogenous psychiatric disorders. Annals of the Russian Academy of Medical Sciences. 2013;68(1):35–41. (In Russ).] doi: 10.15690/vramn.v68i1.535.
  56. Tomasi CD, Salluh J, Soares M, et al. Baseline acetylcholinesterase activity and serotonin plasma levels are not associated with delirium in critically ill patients. Rev Bras Ter Intensiva. 2015;27(2):170–177. doi: 10.5935/0103-507X.20150029.
  57. Peitl V, Vidrih B, Karlović Z, et al. Platelet serotonin concentration and depressive symptoms in patients with schizophrenia. Psychiatry Res. 2016;239:105–110. doi: 10.1016/j.psychres.2016.03.006.
  58. Rihua X, Haiyan X, Krewski D., Guoping H. Plasma concentrations of neurotran smitters and postpartum depression. J Cent South Univ (Med Sci). 2018;43(3):274–281. doi: 10.11817/j.issn.1672-7347.2018.03.007.
  59. Rothhammer V, Mascanfroni ID, Bunse L, et al. Type I interferons and microbial metabolites of tryptophan modulate astrocyte activity and central nervous system inflammation via the aryl hydrocarbon receptor. Nat Med. 2016;22(6):586–597. doi: 10.1038/nm.4106.
  60. Dodd D, Spitzer MH, van Treuren W, et al. A gut bacterial pathway metabolizes aromatic amino acids into nine circulating metabolites. Nature. 2017;551(7682):648–652. doi: 10.1038/nature24661.
  61. Keszthelyi D, Troost FJ, Jonkers DM, et al. Does acute tryptophan depletion affect peripheral serotonin metabolism in the intestine? Am J Clin Nutr. 2012;95(3):603–608. doi: 10.3945/ajcn.111.028589.
  62. Dinan TG, Stanton C, Cryan JF. Psychobiotics: a novel class of psychotropic. Biol Psych. 2013;74(10):720–726. doi: 10.1016/j.biopsych.2013.05.001.
  63. Roman P, Carrillo-Trabalón F, Sánchez-Labraca N, et al. Are probiotic treatments useful on fibromyalgia syndrome or chronic fatigue syndrome patients? Systematic review. Ben Microb. 2018;9(4):603–611. doi: 10.3920/BM2017.0125.
  64. Hubbard TD, Liu Q, Murray IA, et al. Microbiota metabolism promotes synthesis of the human Ah receptor agonist 2,8-dihydroxyquinoline. J Proteome Res. 2019;18(4):1715–1724. doi: 10.1021/acs.jproteome.8b00946.
  65. Aoki R, Aoki-Yoshida A, Suzuki Ch, Takayama Y. Indole-3-pyruvic acid, an aryl hydrocarbon receptor activator, suppresses experimental colitis in mice. J Immunol. 2018;201(12):3683–3693. doi: 10.4049/jimmunol.1701734.
  66. Brito JS, Borges NA, Anjos JS, et al. Aryl hydrocarbon receptor and uremic toxins from gut microbiota in chronic kidney disease patients: is there a relationship? Biochemistry. 2019;58(15):2054–2060. doi: 10.1021/acs.biochem.8b01305.
  67. Addi T, Poitevin S, McKay N, et al. Mechanisms of tissue factor induction by the uremic toxin indole-3 acetic acid through aryl hydrocarbon receptor/nuclear factor-kappa B signaling pathway in human endothelial cells. Arch Toxicol. 2019;93(1):121–136. doi: 10.1007/s00204-018-2328-3.
  68. de Loor H, Poesen R, De Leger W, et al. A liquid chromatography — tandem mass spectrometry method to measure a selected panel of uremic retention solutes derived from endogenous and colonic microbial metabolism. Anal Chim Acta. 2016;936:149–156. doi: 10.1016/j.aca.2016.06.057.
  69. Danaceau JP, Anderson GM, McMahon WM, Crouch DJ. A liquid chromatographic-tandem mass spectrometric method for the analysis of serotonin and related indoles in human whole blood. J Anal Toxicol. 2003;27(7):440–444. doi: 10.1093/jat/27.7.440.
  70. Шевченко В.Е. Современные масс-спектрометрические методы в ранней диагностике рака // Масс-спектрометрия. — 2004. — №1. — С. 103–126. [Shevchenko VE. Modern mass spectrometry methods in early cancer diagnosis. Mass spectrometry. 2004;(1):103–126. (In Russ).]
  71. Паутова А.К., Бедова А.Ю., Саршор Ю.Н., Белобородова Н.В. Определение ароматических микробных метаболитов в сыворотке крови методом газовой хромато-масс-спектрометрии // Журнал аналитической химии. — 2018. — Т.73. — №2. — С. 121–128. [Pautova AK, Bedova AYu, Sarshor YuN, Beloborodova NV. Determination of aromatic microbial metabolites in blood serum by gas chromatography-mass spectrometry. J Analytic Chemistry. 2018;73(2):160–166. (In Russ).] doi: 10.7868/S0044450218020044.
  72. Wu H, Xue R, Dong L, et al. Metabolomic profiling of human urine in hepatocellular carcinoma patients using gas chromatography/mass spectrometry. Anal Chim Acta. 2009;648(1):98–104. doi: 10.1016/j.aca.2009.06.033.
  73. Jiang G, Shen X, Kang H, et al. Serum metabolite profiling of cutaneous T-cell lymphoma based on a multiplatform approach. J Chromatogr B Analyt Technol Biomed Life Sci. 2018;1077–1078. doi: 10.1016/j.jchromb.2018.01.034.
  74. Struck-Lewicka W, Kordalewska M, Bujak R, et al. Urine metabolic fingerprinting using LC–MS and GC–MS reveals metabolite changes in prostate cancer: a pilot study. J Pharm Biomed Anal. 2015;111:351–361. doi: 10.1016/j.jpba.2014.12.026.
  75. Pavlenko D, Giasafaki D, Charalambopoulou G, et al. Carbon adsorbents with dual porosity for efficient removal of uremic toxins and cytokines from human plasma. Sci Rep. 2017;7(1):14914. doi: 10.1038/s41598-017-15116-y.
  76. Phonchaia A, Wilairatb P, Chantiwasa R. Development of a solid-phase extraction method with simple MEKC-UV analysis for simultaneous detection of indole metabolites in human urine after administration of indole dietary supplement. Talanta. 2017;174:314–319. doi: 10.1016/j.talanta.2017.06.019.

Supplementary files

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2. Fig. 1. Scheme of tryptophan metabolism: (1) tryptophan 5-hydroxylase; (2) tryptophan 2,3-dioxygenase; (3) aromatic L-amino acid decarboxylase; (4) indolethylamine N-methyltransferase; (5) kinurenin formamidase; (6) kinurinine 3-monoxidase; (7) aldehyde dehydroxylase, mitochondrial; (8) aldehyde dehydroxylase mitochondrial or aldehyde oxidase; (9) serotonin N-acetyltransferase; (10) acetylserotonin O-methyltransferase (cited in [6])

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3. Fig. 2. The main changes characteristic of tryptophan and its metabolites in severe diseases and critical conditions

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4. Fig. 1. Scheme of tryptophan metabolism: (1) tryptophan 5-hydroxylase; (2) tryptophan 2,3-dioxygenase; (3) aromatic-L-amino acid decarboxylase; (4) indolethylamine N-methyltransferase; (5) kynurenine formamidase; (6) kynurenine 3-monoxidase; (7) mitochondrial aldehyde dehydroxylase; (8) mitochondrial aldehyde dehydroxylase or aldehyde oxidase; (9) serotonin N-acetyltransferase; (10) acetylserotonin O-methyltransferase (Cited from [6])

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5. Fig. 2. The main changes characteristic of tryptophan and its metabolites in severe diseases and critical conditions

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