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Kappus MR, Bajaj JS. Assessment of minimal hepatic encephalopathy (with emphasis on computerized psychometric tests). Clin Liver Dis 2012; 16:43-55. [PMID: 22321464 PMCID: PMC3312030 DOI: 10.1016/j.cld.2011.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Minimal hepatic encephalopathy (MHE) is associated with a high risk of development of overt hepatic encephalopathy, impaired quality of life, and driving accidents. The detection of MHE requires specialized testing because it cannot, by definition, be diagnosed on standard clinical examination. Psychometric and neurophysiologic techniques are often used to test for MHE. Paper-pencil psychometric batteries and computerized tests have proved useful in diagnosing MHE and predicting its outcomes. Neurophysiologic tests also provide useful information. The diagnosis of MHE is an important issue for clinicians and patients alike. Testing strategies depend on the normative data available, patient comfort, and local expertise.
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Safonova MV, Kozlova IV, Ovsiannikova VV, Kvetnoĭ IM. [Hepatic encephalopathy and colon pathology in liver cirrhosis]. EKSPERIMENTAL'NAIA I KLINICHESKAIA GASTROENTEROLOGIIA = EXPERIMENTAL & CLINICAL GASTROENTEROLOGY 2012:20-26. [PMID: 23402187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
to define a role of structural and functional changes of a colon, expression indicators of epithelial cells of mucous coat of colon that produce serotonin and hromogranin-A at in encephalopathy development at liver cirrhoses. We have examined 146 patients with liver cirrhosis of various classes using the clinical, endoscopic, morphologic and immunohistochemical methods. It is established that with increase of a class of a cirrhosis frequency of revealing of a hepatic encephalopathy, structural changes, degree dysbacteriosis of a colon. Progressing of a hepatic encephalopathy at liver cirrhoses associates with development destructive and atrophic changes of a mucous membrane of a colon and a dysbacteriosis. The increase in the morphometric rates of epithelial cells of mucous coat of colon that produce serotonin and hromogranin-A at liver cirrhoses plays a part in development of a manifesting of a hepatic encephalopathy.
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104
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Achiriloaie AF, Kido D, Wycliffe D, Jacobson JP. White matter microsusceptibility changes in patients with hepatic encephalopathy. J Radiol Case Rep 2011; 5:1-7. [PMID: 22470806 DOI: 10.3941/jrcr.v5i8.393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report a new radiological finding in two patients with hepatic encephalopathy. A new susceptibility-weighted (SWI) magnetic resonance imaging sequence revealed multiple bilateral microsusceptibility changes in the corpus callosum and white matter, while the conventional T1 and T2 weighted images were unremarkable. We postulate that the etiology of the microsusceptibility changes may be related to hepatic coagulopathy and other factors, such as impaired cerebral blood flow and brain edema.
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105
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Bajaj JS, Saeian K, Schubert CM, Franco R, Franco J, Heuman DM. Disruption of sleep architecture in minimal hepatic encephalopathy and ghrelin secretion. Aliment Pharmacol Ther 2011; 34:103-5. [PMID: 21631553 DOI: 10.1111/j.1365-2036.2011.04681.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Saji S, Kumar S, Thomas V. A randomized double blind placebo controlled trial of probiotics in minimal hepatic encephalopathy. TROPICAL GASTROENTEROLOGY : OFFICIAL JOURNAL OF THE DIGESTIVE DISEASES FOUNDATION 2011; 32:128-132. [PMID: 21922877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
BACKGROUND AND AIM Hepatic encephalopathy (HE) is a common and serious complication of liver disease. Minimal HE has major impact on all aspects of a patient's life. The aim of this study was to asses the efficacy of probiotics in minimal hepatic encephalopathy in patients with cirrhosis of the liver. METHODS Stable cirrhotics with minimal hepatic encephalopathy diagnosed by number connection test and evoked responses were recruited for the study. The patients were randomized to two groups and the drugs were administered in a double blind fashion. Improvement in number connection test score, evoked response time and arterial ammonia levels were noted. RESULTS 43 patients were recruited for the study; 21 in the probiotics group and 22 in the placebo group. There was no statistically significant change in the parameters like arterial ammonia, evoked responses and number connection test before and after treatment with probiotics when compared to placebo. CONCLUSION Short term administration of probiotics did not produce any significant improvement in the various parameters assessed in patients with minimal hepatic encephalopathy when compared with placebo.
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McPhail MJW, Senvar N, Thomas HC, Taylor-Robinson SD. Modern progress in hepatic encephalopathy. QJM 2010; 103:899-900. [PMID: 20356851 DOI: 10.1093/qjmed/hcq043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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108
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Häussinger D. Hepatic encephalopathy. Acta Gastroenterol Belg 2010; 73:457-464. [PMID: 21299155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome which can develop in the course of chronic and acute liver disease. It is characterized by cognitive and motoric deficits of varying severity. HE is functional in nature, potentially reversible and is thought to reflect the clinical manifestation of a low-grade cerebral edema, which exacerbates in response to ammonia and other precipitating factors, such as electrolyte disturbances, bleeding, infections, high protein diet, diuretics and sedatives. The action of these rather heterogeneous factors integrates at the level of oxidative/nitrosative stress and astrocyte swelling, which is associated with an oxidative/nitrosative stress response in the brain with consequences for signal transduction, neurotransmission, synaptic plasticity and oscillatory networks in the brain. Manifest HE is diagnosed on the basis of clinical symptoms according to the West Haven criteria, whereas diagnosis of minimal HE requires psychometric or neurophysiological testings. Here objective and reproducible measures to assess HE severity, such as critical flicker frequency or evoked potentials are superior to paper pencil tests. Identification and treatment of precipitating factors is the mainstay of HE therapy. Also intravenous ornithine aspartate, vegetable protein, oral branched chain amino acids, lactulose enemas and liver transplantation are considered to be effective. Whereas the efficacy of oral lactulose and non-resorbable antibiotics in the treatment of an acute HE attack is under debate, the beneficial effect of lactulose and rifaximin in the secondary HE prophylaxis has recently been established.
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Ditisheim S, Spahr L. [Hepatic encephalopathy in patients with cirrhosis: new aspects and practical recommendations]. REVUE MEDICALE SUISSE 2010; 6:1667-1671. [PMID: 20939401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Hepatic encephalopathy in patients with cirrhosis may present under various clinical aspects, although minimal and episodic forms are the most frequent in clinical practice. Except for the typical alteration of the level of consciousness, other clinical presentations may exist that require additional diagnostic tests and exclusion of other causes. Management of hepatic encephalopathy includes the eviction of the precipitating factor and prevention of recurrence. Medical therapy is mostly directed at the gut as the main source of neurotoxins, but drugs that aimed at correcting liver and brain alterations demonstrate some efficacy. Liver transplantation should be discussed in the presence of persistent symptoms despite optimal medical therapy.
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Méndez M, Méndez-López M, López L, Begega A, Aller MA, Arias J, Arias JL. Reversal learning impairment and alterations in the prefrontal cortex and the hippocampus in a model of portosystemic hepatic encephalopathy. Acta Neurol Belg 2010; 110:246-254. [PMID: 21114133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Patients with liver dysfunction often suffer from hepatic encephalopathy (HE), a neurological complication that affects attention and memory. Various experimental animal models have been used to study HE, the most frequently used being the portocaval shunt (PCS). In order to determine brain substrates of cognitive impairment in this model, we assessed reversal learning and c-Fos expression in a rat model of portosystemic derivation. PCS and sham-operated rats (SHAM) were tested for reversal learning. Brains were processed for c-Fos immunocytochemistry. The total number of c-Fos positive nuclei was quantified in the prefrontal cortex and hippocampus. The spatial reference memory task showed no differences between groups in escape latencies. The no-platform probe test showed that both the PCS and the SHAM learned the location of platform. However, the PCS group perseverated in the old target during reversal. The PCS group presented less c-Fos- positive cells in prelimbic cortex, CA1 and dentate gyrus of the dorsal hippocampus than SHAM. Overall, these results suggest that this specific model of portosystemic hepatic encephalopathy produces reversal learning impairment that could be linked to dysfunction in neuronal activity in the prefrontal cortex and hippocampus.
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Torre Delgadillo A. [Liver diseases. Hepatic encephalopathy]. REVISTA DE GASTROENTEROLOGIA DE MEXICO 2010; 75 Suppl 1:190-192. [PMID: 20959247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Márquez-Aguirre AL, Canales-Aguirre AA, Gómez-Pinedo U, Gálvez-Gastélum FJ. [Molecular aspects of hepatic encephalopathy]. Neurologia 2010; 25:239-247. [PMID: 20609302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023] Open
Abstract
INTRODUCTION Liver fibrosis and its end stage, cirrhosis, is an enormous worldwide health problem. Hepatic encephalopathy (HE) or portal-systemic encephalopathy continues to be a major clinical problem of long-term cirrhosis. In this review we emphasise the molecular basis of HE and the involvement of oxidative stress in the development of this disease. BACKGROUND Several studies suggest that the pathogenesis of HE could be multifactorial and have implicated different factors, such as alterations in blood brain barrier, substances; such as ammonia and manganese, neurotransmission disorders such as dopamine, glutamate and GABA. DEVELOPMENT HE is a severe complication of both acute and chronic liver failure. Neuropathologically, it is characterized by astrocyte changes known as Alzheimer type II astrocytosis. In addition, astrocytes manifest altered expression of astrocyte-specific proteins, such as, glial fibrillary acidic protein, glutamine synthetase, monoamine oxidase and peripheral type benzodiazepine receptors. CONCLUSIONS HE is a complex neuropsychiatric syndrome associated with liver failure. These alterations are products of increases in oxidative stress in brain due to neurotoxin activity. The main strategy for HE treatment is directed at ammonia reduction, which can be achieved either by decreasing its absorption/production or increasing its removal.
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Bémeur C, Desjardins P, Butterworth RF. Antioxidant and anti-inflammatory effects of mild hypothermia in the attenuation of liver injury due to azoxymethane toxicity in the mouse. Metab Brain Dis 2010; 25:23-9. [PMID: 20198438 DOI: 10.1007/s11011-010-9186-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2009] [Accepted: 01/06/2010] [Indexed: 12/19/2022]
Abstract
Previous studies have demonstrated protective effects of mild hypothermia following acetaminophen (APAP)-induced acute liver failure (ALF). However, effects of this treatment in ALF due to other toxins have not yet been fully investigated. In the present study, the effects of mild hypothermia in relation to liver pathology, hepatic and cerebral glutathione, plasma ammonia concentrations, progression of encephalopathy, cerebral edema, and plasma proinflammatory cytokines were assessed in mice with ALF resulting from azoxymethane (AOM) hepatotoxicity, a well characterized model of toxic liver injury. Male C57BL/6 mice were treated with AOM (100 microg/g; i.p.) or saline and sacrificed at coma stages of encephalopathy in parallel with AOM mice maintained mildly hypothermic (35 degrees C). AOM treatment led to hepatic damage, significant increase in plasma transaminase activity, decreased hepatic glutathione levels, and brain GSH/GSSG ratios as well as selective increases in expression of plasma proinflammatory cytokines. Mild hypothermia resulted in reduced hepatic damage, improvement in neurological function, normalization of glutathione levels, and selective attenuation in expression of circulating proinflammatory cytokines. These findings demonstrate that the beneficial effects of mild hypothermia in experimental AOM-induced ALF involve both antioxidant and anti-inflammatory mechanisms.
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Montoliu C, Rodrigo R, Monfort P, Llansola M, Cauli O, Boix J, Elmlili N, Agusti A, Felipo V. Cyclic GMP pathways in hepatic encephalopathy. Neurological and therapeutic implications. Metab Brain Dis 2010; 25:39-48. [PMID: 20195723 DOI: 10.1007/s11011-010-9184-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Accepted: 08/20/2009] [Indexed: 01/16/2023]
Abstract
Cyclic GMP (cGMP) modulates important cerebral processes including some forms of learning and memory. cGMP pathways are strongly altered in hyperammonemia and hepatic encephalopathy (HE). Patients with liver cirrhosis show reduced intracellular cGMP in lymphocytes, increased cGMP in plasma and increased activation of soluble guanylate cyclase by nitric oxide (NO) in lymphocytes, which correlates with minimal HE assessed by psychometric tests. Activation of soluble guanylate cyclase by NO is also increased in cerebral cortex, but reduced in cerebellum, from patients who died with HE. This opposite alteration is reproduced in vivo in rats with chronic hyperammonemia or HE. A main pathway modulating cGMP levels in brain is the glutamate-NO-cGMP pathway. The function of this pathway is impaired both in cerebellum and cortex of rats with hyperammonemia or HE. Impairment of this pathway is responsible for reduced ability to learn some types of tasks. Restoring the pathway and cGMP levels in brain restores learning ability. This may be achieved by administering phosphodiesterase inhibitors (zaprinast, sildenafil), cGMP, anti-inflammatories (ibuprofen) or antagonists of GABAA receptors (bicuculline). These data support that increasing cGMP by safe pharmacological means may be a new therapeutic approach to improve cognitive function in patients with minimal or clinical HE.
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115
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Bajaj JS. Current and future diagnosis of hepatic encephalopathy. Metab Brain Dis 2010; 25:107-10. [PMID: 20213105 DOI: 10.1007/s11011-010-9176-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Accepted: 01/28/2010] [Indexed: 02/07/2023]
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116
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Córdoba J, García-Martinez R, Simón-Talero M. Hyponatremic and hepatic encephalopathies: similarities, differences and coexistence. Metab Brain Dis 2010; 25:73-80. [PMID: 20217202 DOI: 10.1007/s11011-010-9172-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 11/27/2009] [Indexed: 12/11/2022]
Abstract
Hyponatremic and hepatic encephalopathy are common causes of metabolic encephalopathy that may coexist in patients with cirrhosis. The clinical picture is common to any metabolic encephalopathy and is characterized by a confusional syndrome that may evolve into coma. Chronic mild or minimal manifestations can be seen in both, but motor symptoms are more common in hepatic encephalopathy. Recent advances show that in addition to clinical manifestations both encephalopathies share some pathogenetic mechanisms. Dysfunction of astrocytes, osmotic changes in the brain and brain edema are present in both situations. Recognition of these abnormalities is important to plan therapy. New drugs that affect brain hydration may be useful for both encephalopathies.
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Campagna F, Biancardi A, Cillo U, Gatta A, Amodio P. Neurocognitive-neurological complications of liver transplantation: a review. Metab Brain Dis 2010; 25:115-24. [PMID: 20204483 DOI: 10.1007/s11011-010-9183-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 01/28/2010] [Indexed: 12/20/2022]
Abstract
Neurological complications are common after liver transplantation (LT) and they are associated with a significant morbidity. Long-term effects of LT on cognitive and psychological outcomes are not clear. The objective of this study was to summarize the present knowledge on the neurological and cognitive complications of LT, resulting from a systematic review of the literature in the last 10 years. Several studies have investigated the incidence and the pathophysiology of neurological complications; in contrast, the knowledge of cognitive and psychological status after LT is poor. Currently, the effect of LT on mental performance is debated. Some studies have shown an improvement of cognitive function after OLTX and, at the same time, a persistence of different cognitive deficits. In addition, the quality of life (QoL) and the psychological status after LT seem to improve but LT recipients have significant deficiencies in most QoL domains. Consequently, future studies are necessary in order to investigate cognitive alterations and QoL in LT recipients.
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Keiding S, Sørensen M, Munk OL, Bender D. Human (13)N-ammonia PET studies: the importance of measuring (13)N-ammonia metabolites in blood. Metab Brain Dis 2010; 25:49-56. [PMID: 20217201 PMCID: PMC2850514 DOI: 10.1007/s11011-010-9181-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Accepted: 01/28/2010] [Indexed: 11/12/2022]
Abstract
Dynamic (13)N-ammonia PET is used to assess ammonia metabolism in brain, liver and muscle based on kinetic modeling of metabolic pathways, using arterial blood (13)N-ammonia as input function. Rosenspire et al. (1990) introduced a solid phase extraction procedure for fractionation of (13)N-content in blood into (13)N-ammonia, (13)N-urea, (13)N-glutamine and (13)N-glutamate. Due to a radioactive half-life for (13)N of 10 min, the procedure is not suitable for blood samples taken beyond 5-7 min after tracer injection. By modifying Rosenspire's method, we established a method enabling analysis of up to 10 blood samples in the course of 30 min. The modified procedure was validated by HPLC and by 30-min reproducibility studies in humans examined by duplicate (13)N-ammonia injections with a 60-min interval. Blood data from a (13)N-ammonia brain PET study (from Keiding et al. 2006) showed: (1) time courses of (13)N-ammonia fractions could be described adequately by double exponential functions; (2) metabolic conversion of (13)N-ammonia to (13)N-metabolites were in the order: healthy subjects > cirrhotic patients without HE > cirrhotic patients with HE; (3) kinetics of initial tracer distribution in tissue can be assessed by using total (13)N-concentration in blood as input function, whereas assessment of metabolic processes requires (13)N-ammonia measurements.
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119
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McPhail MJW, Taylor-Robinson SD. The role of magnetic resonance imaging and spectroscopy in hepatic encephalopathy. Metab Brain Dis 2010; 25:65-72. [PMID: 20221679 DOI: 10.1007/s11011-010-9171-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 01/28/2010] [Indexed: 01/22/2023]
Abstract
Hepatic encephalopathy (HE) is a diverse manifestation of acute and chronic liver failure, ranging from cognitive impairment, only detectable on psychometric evaluation through to confusion, coma and death from cerebral oedema. While there is widespread acceptance of its importance, there is little consensus on how best to diagnose and monitor HE. Clinical descriptions, psychometric testing, electroencephalography and magnetic resonance (MR) imaging (and lately, MR spectroscopy) have all been proposed. MR techniques, in contrast to other modalities, have the benefit of objectivity and of being able to interrogate the brain directly with respect to changes in brain size, function and the metabolic disturbances thought to underlie HE, particularly in the context of astrocyte swelling. Modern clinical MRI scanners with multinuclear MR spectroscopy capabilities and brain mapping software can demonstrate structural and functional cellular changes using volumetric MRI, magnetization transfer MRI, diffusion-weighting MRI, functional MRI with oxygenation measurements and in vivo and in vitro (1)H and (31)P MR spectroscopy. This review describes the relative merits of these techniques and provides guidance on the directions for future research and translation into clinical practice.
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120
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Gjedde A, Keiding S, Vilstrup H, Iversen P. No oxygen delivery limitation in hepatic encephalopathy. Metab Brain Dis 2010; 25:57-63. [PMID: 20182779 DOI: 10.1007/s11011-010-9179-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/28/2010] [Indexed: 10/19/2022]
Abstract
Hepatic encephalopathy is a condition of reduced brain functioning in which both blood flow and brain energy metabolism declined. It is not known whether blood flow or metabolism is the primary limiting factor of brain function in this condition. We used calculations of mitochondrial oxygen tension to choose between cause and effect in three groups of volunteers, including healthy control subjects (HC), patients with cirrhosis of the liver without hepatic encephalopathy (CL), and patients with cirrhosis with acute hepatic encephalopathy. Compared to HC subjects, blood flow and energy metabolism had declined in all gray matter regions of the brain in patients with HE but not significantly in patients with CL. Analysis of flow-metabolism coupling indicated that blood flow declined in HE as a consequence of reduced brain energy metabolism implied by the calculation of increased mitochondrial oxygen tensions that patients with HE were unable to utilize. We ascribe the inability to use the delivered oxygen of patients with HE to a specific inhibition associated with oxidative metabolism in mitochondria.
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121
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Heins J, Zwingmann C. Organic osmolytes in hyponatremia and ammonia toxicity. Metab Brain Dis 2010; 25:81-9. [PMID: 20195726 DOI: 10.1007/s11011-010-9170-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Accepted: 01/28/2010] [Indexed: 01/06/2023]
Abstract
Hyperammonemia (HA) is a major and commonly observed feature of hepatic encephalopathy. Furthermore, hyponatremia is an important pathogenetic factor in patients with hepatic encephalopathy. Both conditions have some features in common, such as the release of organic osmolytes, which might be an adaptive mechanism against cell swelling. However, the consequence of a possible relationship between osmoregulatory response in hyperammonemia and hyponatremia is not completely understood. This review gives a short introduction into the pathogenesis of hepatic encephalopathy and hyponatremia. For a comparison of both pathological events, some basics on cellular osmo- and volume regulation are explained, in particular as the mechanisms involved in the adaption of the cell to volume changes can be different under both pathological conditions. The role of brain glutamine and organic osmolytes in hyponatremia and hyperammonemia and their combination are discussed based on findings in experimental animal models, and finally on data obtained from primary astrocytes in culture. The observations that the decrease of brain organic osmolytes in astrocytes not adequately compensate for an increased intracellular osmolarity caused by glutamine are consistent with results obtained after chronic hyponatremia in rats, in which the release of osmolytes does not protect from ammonia-induced brain edema. Furthermore, a decrease in intracellular osmolarity is attributed both to the release and a reduced de novo synthesis of amino acids.
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Chastre A, Jiang W, Desjardins P, Butterworth RF. Ammonia and proinflammatory cytokines modify expression of genes coding for astrocytic proteins implicated in brain edema in acute liver failure. Metab Brain Dis 2010; 25:17-21. [PMID: 20217200 DOI: 10.1007/s11011-010-9185-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2009] [Accepted: 01/20/2010] [Indexed: 10/19/2022]
Abstract
There is evidence to suggest that, in acute liver failure (ALF), brain ammonia and proinflammatory cytokines may act synergistically to cause brain edema and its complications (intracranial hypertension, brain herniation). However, the molecular mechanisms involved remain to be established. In order to address this issue, semi-quantitative RT-PCR was used to measure the expression of genes coding for astrocytic proteins with an established role in cell volume regulation in cerebral cortical astrocytes exposed to toxic agents previously identified in experimental and clinical ALF. Such agents include ammonia, the proinflammatory cytokine interleukin-1beta (IL-1beta) and combinations of the two. Exposure of cultured astrocytes to recombinant IL-1beta (but not ammonia) resulted in increased expression of aquaporin-4 (AQP-4). Both ammonia and proinflammatory mediators led to decreased expression of glial fibrillary acidic protein (GFAP), a cytoskeletal protein, but these effects were not additive. On the other hand, heme oxygenase-1 (HO-1) and inducible nitric oxide synthase (iNOS) expression were significantly increased by exposure to both ammonia and proinflammatory mediators and although modest, these effects were additive suggestive of a synergistic mechanism. These findings suggest that worsening of brain edema and its complications in ALF due to proinflammatory mechanisms may result from exacerbation of oxidative stress-related mechanisms rather than upregulation of AQP-4 or decreases in expression of the astrocytic structural protein GFAP.
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Jayakumar AR, Norenberg MD. The Na-K-Cl Co-transporter in astrocyte swelling. Metab Brain Dis 2010; 25:31-8. [PMID: 20336356 DOI: 10.1007/s11011-010-9180-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 01/28/2010] [Indexed: 10/19/2022]
Abstract
Ion channels, exchangers and transporters are known to be involved in cell volume regulation. A disturbance in one or more of these systems may result in loss of ion homeostasis and cell swelling. In particular, activation of the Na(+)-K(+)-Cl(-) cotransporters has been shown to regulate cell volume in many conditions. The Na(+)-K(+)-Cl- cotransporters (NKCC) are a class of membrane proteins that transport Na, K, and Cl ions into and out of a wide variety of epithelial and nonepithelial cells. Studies have established the role of NKCC1 in astrocyte swelling/brain edema in ischemia and trauma. Our recent studies suggest that NKCC1 activation is also involved in astrocyte swelling induced by ammonia and in the brain edema in the thioacetamide model of acute liver failure. This review will focus on mechanisms of NKCC1 activation and its contribution to astrocyte swelling/brain edema in neurological disorders, with particular emphasis on ammonia neurotoxicity and acute liver failure.
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124
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El-Hattab AW, Li FY, Schmitt E, Zhang S, Craigen WJ, Wong LJC. MPV17-associated hepatocerebral mitochondrial DNA depletion syndrome: new patients and novel mutations. Mol Genet Metab 2010; 99:300-8. [PMID: 20074988 DOI: 10.1016/j.ymgme.2009.10.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 10/07/2009] [Accepted: 10/07/2009] [Indexed: 12/27/2022]
Abstract
Mitochondrial DNA depletion syndromes are autosomal recessive diseases characterized by a severe decrease in mitochondrial DNA content leading to dysfunction of the affected organ. They are phenotypically heterogeneous and classified as myopathic, encephalomyopathic, or hepatocerebral. The latter group has been associated with mutations in TWINKLE,POLG1, DGUOK genes and recently with mutations in the MPV17 gene. MPV17 encodes a mitochondrial inner membrane protein and plays an as yet poorly understood role in mitochondrial DNA maintenance. Mutations in the MPV17 gene have been reported in patients who came to medical attention during infancy with liver failure, hypoglycemia, failure-to-thrive and neurological symptoms. In addition, a homozygous p.R50Q mutation has been identified in patients with Navajo neurohepatopathy. To date, 13 different mutations in 21 patients have been reported. We report eight new patients with seven novel mutations, including four missense mutations (c.262A>G (p.K88E), c.280G>C (p.G94R), c.293C>T (p.P98L), and c.485C>A (p.A162D)), one in-frame deletion (c.271_273del3 (p.L91del)), one splice site substitution (c.186+2T>C), and one insertion (c.22_23insC). The p.R50Q mutation, which occurs in a CpG dinucleotide, is the most common MPV17 mutation and, to date, has only been found in the homozygous state. Clinically, patients homozygous for p.R50Q or compound heterozygous for the p.G94R and p.P98L mutations have a better prognosis, with all the other mutations associated with early death if not treated by liver transplantation. Localizing the mutations within the predicted MPV17 protein structure reveals clustering of mutations in the region of the putative protein kinase C phosphorylation site.
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Yang X, Bosoi CR, Jiang W, Tremblay M, Rose CF. Portacaval anastomosis-induced hyperammonemia does not lead to oxidative stress. Metab Brain Dis 2010; 25:11-5. [PMID: 20195725 DOI: 10.1007/s11011-010-9174-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Accepted: 01/28/2010] [Indexed: 10/19/2022]
Abstract
Ammonia is neurotoxic and believed to play a major role in the pathogenesis of hepatic encephalopathy (HE). It has been demonstrated, in vitro and in vivo, that acute and high ammonia treatment induces oxidative stress. Reactive oxygen species (ROS) are highly reactive and can lead to oxidization of proteins resulting in protein damage. The present study was aimed to assess oxidative status of proteins in plasma and brain (frontal cortex) of rats with 4-week portacaval anastomosis (PCA). Markers of oxidative stress, 4-hydroxy-2-nonenal (HNE) and carbonylation were evaluated by immunoblotting in plasma and frontal cortex. Western blot analysis did not demonstrate a significant difference in either HNE-linked or carbonyl derivatives on proteins between PCA and sham-operated control rats in both plasma and frontal cortex. The present study suggests PCA-induced hyperammonemia does not lead to systemic or central oxidative stress.
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