Boletín de antídotos de Cataluña

Antídots; Intoxicació aguda; CatalunyaAntidote; Acute intoxication; CataloniaAntídotos; Intoxicación aguda; CataluñaNoves pautes de dosificació de la N-acetilcisteïna en la intoxicació per paracetamolNuevas pautas de dosificación de la N-acetilcisteína en la intoxicación por paracetamo

Boletín de antídotos de Cataluña

Antídots; Intoxicació aguda; CatalunyaAntidote; Acute intoxication; CataloniaAntídotos; Intoxicación aguda; CataluñaNoves pautes de dosificació de la N-acetilcisteïna en la intoxicació per paracetamolNuevas pautas de dosificación de la N-acetilcisteína en la intoxicación por paracetamo

Nuevas pautas de dosificación de la Nacetilcisteína en la intoxicación por paracetamol

Dosificació; N-acetilcisteïna; Intoxicació; ParacetamolDosificación; N-acetilcisteína; Intoxicación; ParacetamolDosage; N-acetylcysteine; Intoxication; ParacetamolArticle que parla sobre la introducció de la N-acetilcisteïna en el tractament de la intoxicació per paracetamol

Methionine Cycle Rewiring by Targeting miR-873-5p Modulates Ammonia Metabolism to Protect the Liver from Acetaminophen

Drug-induced liver injury (DILI) development is commonly associated with acetaminophen (APAP) overdose, where glutathione scavenging leads to mitochondrial dysfunction and hepatocyte death. DILI is a severe disorder without effective late-stage treatment, since N-acetyl cysteine must be administered 8 h after overdose to be efficient. Ammonia homeostasis is altered during liver diseases and, during DILI, it is accompanied by decreased glycine N-methyltransferase (GNMT) expression and S-adenosylmethionine (AdoMet) levels that suggest a reduced methionine cycle. Anti-miR-873-5p treatment prevents cell death in primary hepatocytes and the appearance of necrotic areas in liver from APAP-administered mice. In our study, we demonstrate a GNMT and methionine cycle activity restoration by the anti-miR-873-5p that reduces mitochondrial dysfunction and oxidative stress. The lack of hyperammoniemia caused by the therapy results in a decreased urea cycle, enhancing the synthesis of polyamines from ornithine and AdoMet and thus impacting the observed recovery of mitochondria and hepatocyte proliferation for regeneration. In summary, anti-miR-873-5p appears to be an effective therapy against APAP-induced liver injury, where the restoration of GNMT and the methionine cycle may prevent mitochondrial dysfunction while activating hepatocyte proliferative response.We thank Ministerio de Ciencia e Innovación, Programa Retos-Colaboración RTC2019- 007125-1 (for J.S. and M.L.M.-C.); Instituto de Salud Carlos III: Proyectos de Investigación en Salud DTS20/00138 (for J.S. and M.L.M.-C.), PI20/00690 (for R.J.) and PT20/000127 (for M.I.L.); CIBERehd: EHD21TRF01/2022 (to M.L.M.-C.); Departamento de Industria del Gobierno Vasco (for M.L.M.-C.); Ministerio de Ciencia, Innovación y Universidades MICINN: PID2020-117116RB-I00 and RTI2018- 096759-1-100 integrado en el Plan Estatal de Investigación Cientifica y Técnica y Innovación, cofinanciado con Fondos FEDER (for M.L.M.-C. and T.C.D., respectively); BIOEF (Basque Foundation for Innovation and Health Research); Asociación Española contra el Cáncer (AECC) (to M.L.M.-C., T.C.D.); AECC: GCTRA18006CARR (to A.C.); Fundación Científica de la Asociación Española Contra el Cancer (AECC Scientific Foundation) Rare Tumor Calls 2017 (for M.L.M.); La Caixa Foundation Program (for M.L.M.); BFU2015-70067-REDC, BFU2016-77408-R and BES-2017-080435 (MINECO/FEDER, UE); Ministerio de Ciencia, Innovación y universidades PID2019-108787RB-100 (to A.C.), PID2019- 109055RB-I00 (L.A.M.-C.), PID2020-117941RB-100 (to F.J.C.); Spanish Ministry of Economy and Competitiveness Grants BFU2013-47531-R and BFU2016-77408-R (L.A.M.-C.) and the FIGHT-CNNM2 project from the EJP RD Joint Transnational Call (JTC2019) (Ref. AC19/00073) (for L.A.M.-C.); Comunidad de Madrid: EXOHEP-CM S2017/BMD-3727 and NanoLiver-CM Y2018/NMT-4949 co-funded by European Structural and Investment Fund and COST Action CA17112 (to F.J.C.); Vencer el Cáncer Foundation (to A.C.); European Research Council: Consolidator Grant 819242 (to A.C.); CIBERONC and CIBERehd were funded by the Instituto de Salud Carlos III and Cofunded by FEDER funds. Partial funding for open access charge: Universidad de Málag

Methionine cycle rewiring by targeting miR-873-5p modulates ammonia metabolism to protect the liver from acetaminophen

Drug-induced liver injury (DILI) development is commonly associated with acetaminophen (APAP) overdose, where glutathione scavenging leads to mitochondrial dysfunction and hepatocyte death. DILI is a severe disorder without effective late-stage treatment, since N-acetyl cysteine must be administered 8 h after overdose to be efficient. Ammonia homeostasis is altered during liver diseases and, during DILI, it is accompanied by decreased glycine N-methyltransferase (GNMT) expression and S-adenosylmethionine (AdoMet) levels that suggest a reduced methionine cycle. Anti-miR-873-5p treatment prevents cell death in primary hepatocytes and the appearance of necrotic areas in liver from APAP-administered mice. In our study, we demonstrate a GNMT and methionine cycle activity restoration by the anti-miR-873-5p that reduces mitochondrial dysfunction and oxidative stress. The lack of hyperammoniemia caused by the therapy results in a decreased urea cycle, enhancing the synthesis of polyamines from ornithine and AdoMet and thus impacting the observed recovery of mitochondria and hepatocyte proliferation for regeneration. In summary, anti-miR-873-5p appears to be an effective therapy against APAP-induced liver injury, where the restoration of GNMT and the methionine cycle may prevent mitochondrial dysfunction while activating hepatocyte proliferative response

Mechanism of Paracetamol (Acetaminophen) induced Hypothermia

Paracetamol is a potent analgesic and antipyretic with limited side effects compared to the nonsteroidal anti-inflammatory drugs (NSAIDs) and opiates. Worldwide paracetamol is commonly used to treat pain and fever in both children and adults. Although, this drug has been in clinical use for more than a century, the mechanisms of action are not fully understood. Historically some of the actions of paracetamol were attributed to the inhibition of central cyclooxygenase (COX-1 and COX-2) enzymes however given the weak inhibitory effects on COX-1 and COX-2 enzymes, alternative targets have been suggested including a possible novel COX-3. The inhibition of COX-2 is accepted as the mechanism by which paracetamol reduces core temperature (Tc) in febrile animals. However, in non-febrile animals where COX-2 is not induced, paracetamol has also been shown to cause hypothermia by a mechanism that is not fully understood. Both the reduction of pyresis and induction of hypothermia can only occur when peripheral metabolic rate decreases and/or heat loss increases. In terms of antipyresis and hypothermia, the inhibition of lipolysis, fatty acid oxidation and mitochondria function are obvious alternative targets. Studies were undertaken to identify and characterise the putative COX-3 at protein and mRNA level using western blot analysis and reverse transcription polymerase chain reaction (RT-PCR) in mouse brain endothelial cells (b.End3) and whole brain tissues isolated from male C57BL/6 mice. Additional studies were also undertaken to assess if the hypothermic properties of paracetamol could be attributed to direct inhibition of thermogenic pathways in both 3T3-L1 adipocytes and primary brown adipocytes isolated from male Wistar rats. Adipocytes and isolated mitochondria were exposed to paracetamol and lipolysis, fatty acid oxidation (FAO), mitochondrial electron transport chain (ETC), assessed by measuring oxygen consumption rate (OCR). In these studies no expression of the COX-3 protein could be detected in brain endothelial cells and homogenates and no evidence of a COX-3 was detected at mRNA level. However, paracetamol caused a significant decrease (upto 70%; P<0.01, from control) in both basal and stimulated lipolysis at 1, 3 and 24 hours without affecting cell viability. Paracetamol (10 mM) and its metabolite N-acetyl-p-benzoquinone imine (NAPQI) at 50 µM also significantly (P<0.01, from control), reduced endogenous and exogenous FAO by 50% and 70% respectively. NAPQI (50 µM) had limited effect on mitochondrial uncoupling. Finally, paracetamol and other antipyretic compounds also significantly reduced ETC activity (upto 90%; P<0.01, from control). Both the maintenance of normal body temperature (Tb) and the induction of pyresis require increased mitochondrial ETC activity normally initiated centrally and driven peripherally by reduction of substrates such as fatty acids and glucose. The failure to identify the COX-3 protein and the direct inhibition of lipolysis, FAO and ETC activity indicate that antipyretic actions of paracetamol could partly be attributed to it actions on peripheral energy generation systems and provide new drug targets for reducing fever and chemically inducing hypothermia

Development of a non-mammalian, pre-clinical screening tool for the predictive analysis of drug toxicity

The failure to predict drug-induced toxicity reactions is still a major problem contributing to a high attrition rate and tremendous cost in drug development. Xenopus laevis embryos are amenable for the early stage medium to high throughput small molecule screens. We hypothesise Xenopus embryos can assist in vitro drug-induced toxicity safety assessment in the early phases of drug development before moving on to expensive preclinical trials in mammals. The objective of this study was to assess the use of Xenopus laevis embryos for the prediction of organ-specific toxicity. To do this I used drugs known to generate toxicity reactions in humans. First of all I determined that Xenopus embryos treated with a drug from the age of stage 38 until stage 45, was an appropriate assay for the prediction of drug-induced toxicity. The embryos expressed major drug metabolism enzymes including CYP2E1, CYP2D6, CYP3A4 and glutathione S-transferases, sulphotransferases and glucuronosyltransferases. They also expressed KCNH2, which encodes the α-subunit protein of the potassium ion channel KV11.1 that contributes to heart electrophysiology. For drug-induced liver injury, I used paracetamol treatment. Xenopus laevis embryos treated with paracetamol (0-5 mM) generated predicted paracetamol metabolites, had a dose-dependent depletion of free glutathione and increased expression of microRNA-122 (miR-122) in tissue that did not contain the liver. To investigate drug-induced cardiotoxicity, I treated Xenopus embryos with doxorubicin (0-100 µM) and terfenadine (050 µM). Embryo heart rates increased and decreased with these drugs respectively and arrhythmias occurred with both drug treatments. Embryos treated with doxorubicin had an increasing amount of arrhythmia that correlated with an increasing dose of doxorubicin treatment. Terfenadine treatment induced arrhythmia at a rate that was not concentration dependent. Wholemount in situ hybridisation (WISH) revealed the Xenopus embryos also express miR-208 specifically in the heart, similar to mammalian models. We conclude that Xenopus laevis embryos exhibit some similar characterisations of drug-induced hepatotoxicity and cardiotoxicity observed in mammalian models. These data indicate the Xenopus embryo could be a useful model to assess drug-induced toxicity and aid lead compound prioritisation in early drug development