Orientador: Fernando Gomes Romeiro / Resumo: Aminoácidos de cadeia ramificada aumentam a perfusão cerebral de pacientes com encefalopatia hepática (EH), mas o aminoácido responsável por esse aumento e os mecanismos envolvidos ainda não são conhecidos. Este estudo comparou a perfusão cerebral e a melhora clínica durante a suplementação de leucina ou isoleucina. Após a randomização, 27 indivíduos com cirrose e EH receberam suplementos de leucina ou isoleucina por um ano. Exames de tomografia computadorizada por emissão de fóton único (SPECT) e cintilografia cerebral dinâmica (DBS) foram realizados antes do estudo e após 1, 8 e 12 meses de suplementação. Apenas o grupo que recebeu isoleucina teve aumento da perfusão cerebral aos 8 meses de tratamento pelo exame de SPECT e pela cintilografia (p<0,001 e p = 0,05, respectivamente), também observado pelo SPECT aos 12 meses de suplementação (p < 0,05). O aumento do fluxo cerebral foi associado a melhora da EH aos 8 e 12 meses de suplementação (p=0,008 e 0,004, respectivamente), porém essa melhora não foi observada no grupo que recebeu leucina (p=0,313 e 0,055, respectivamente). A suplementação com isoleucina obteve melhor impacto na restauração da perfusão cerebral em pacientes com EH. / Abstract: Branched-chain amino acids increase the brain perfusion of patients with hepatic encephalopathy (HE), but the amino acid and the mechanisms involved are still unknown. This study compared brain perfusion and clinical improvement during leucine or isoleucine supplementation. After randomization, 27 subjects with cirrhosis and HE received leucine or isoleucine supplements for one year. Brain single photon emission computed tomography (SPECT) and dynamic brain scintigraphy (DBS) were performed pretreatment and at 1, 8 and 12 months of supplementation. Brain perfusion was increased only in the isoleucine group at 8 months of treatment by both SPECT and DBS (p<0.001 and p = 0.05, respectively) and by SPECT at the 12th month (p < 0.05). This was associated with hepatic encephalopathy improvement at 8 and 12 months (p=0.008 and 0.004, respectively), which was not observed in the leucine group (p=0.313 and 0.055, respectively). Isoleucine supplementation achieved a better impact on brain perfusion restoration in HE. / Doutor

La réponse à l’agression est à la fois neuroendocrinienne, neurovégétative et comportementale. Elle implique particulièrement l’amygdale. Celle-ci joue en effet un rôle dans l’anxiété et la peur mais également dans la constitution d’un syndrome de stress post-traumatique (i.e. SSPT). La réponse comportementale à une situation de stress a été peu étudiée chez les patients admis dans un service de Réanimation, alors que des études indiquent qu’une réponse inadaptée de l’axe corticotrope ou du système nerveux autonome serait associée à une surmortalité ou la survenue d’une défaillance multiviscérale. Au décours de leur séjour en réanimation, les patients sont à haut risque de développer des troubles psychologiques (i.e. anxiété, dépression et SSPT) et cognitifs (i.e. affectant préférentiellement la mémoire et les fonctions exécutives) qui ont un impact majeur sur leur qualité de vie et qui seraient proportionnels à la sévérité de leur maladie aiguë et de son retentissement neuro-comportemental. L’objet de notre travail a été d’une part, de décrire quantitativement et qualitativement l’anxiété des patients admis de réanimation et d’en déterminer sa valeur pronostique ; d’autre part, d’étudier le lien entre activation amygdalienne et syndrome post-traumatique dans un modèle murin de sepsis par ligature-ponction caecale (i.e. CLP). Notre étude observationnelle a porté sur 354 patients (Age, 63 ans [49-73] ; Sexe F/H, 137/217) admis dans trois services de réanimation d’Île de France entre Janvier 2014 et Septembre 2016. L’anxiété était en médiane d’intensité modérée, selon l’échelle visuelle analogique (4 [1-6) et le questionnaire STAI (41 [31-53]). La moitié des patients rapportaient se sentir vulnérables (54%) ; considérer leur état grave (67 %) et avoir peur de mourir (45%). Une défaillance d’organe a été observée chez 157 (45%) des patients. Une valeur de STAI ≥ 40 (OR 1,69, 95%CI [1,02-2,84]) était associée à la survenue d’une défaillance d’organe après ajustement sur le score de défaillance d’organe SOFA à J1, la mise en route d’une ventilation mécanique non-invasive (OR 4,93 ; 95%CI [2,9-9,4]) et la gravité d’une pathologie préexistante selon le score Knaus (OC2,01 95%CI [1,21-3,33]) et la peur de mourir (OR 0,55 [0,33-0,92]). Celle-ci était significativement associée à un risque moindre de défaillance parmi les patients ayant une maladie aiguë sévère, définie par un score IGS-2 > 30 (58% vs. 37%). Cette étude indique que l’évaluation de l’anxiété est utile pour estimer le risque d’aggravation des patients de réanimation mais indique également que si son intensité est positivement corrélée à la survenue d’une défaillance, un défaut de perception d’un danger (tel que l’exprimerait la peur de mourir) en augmenterait le risque. Notre étude expérimentale a mis en évidence une activation précoce (i.e. à H6 de la CLP) et transitoire des neurones CAMK-II positif du noyau central de l’amygdale (CeA) et des anomalies tardives (i.e. J15 après CLP) de l’open-field test (test en libre champ) et du Fear-conditionning (test de formation de la mémoire aversive), traduisant respectivement un comportement type anxieux et une hypermémorisation de la peur, qui s’apparenterait à un SSPT. Nous avons procédé à une inhibition pharmacogénétique par transfection virale des neurones CAMKII, qui a entraîné une réduction de l’hyper-mémorisation aversive induite par le sepsis. L’enregistrement électrophysiologique intra-amygadalienne a mis en évidence une activité pro-épileptique ou épileptique chez les souris septiques. L’administration d’un antiépileptique, le levetiracetam au cours des 24 premières heures de la CLP a résulté en une diminution de la mortalité, de l’activation des neurones CAMKII du noyau central de l’amygdale et de l’hyper-mémorisation aversive induites par le sepsis. (...) / Systemic insults trigger neuroendocrine, neurovegetative and behavioural responses. Amygdala is particularly involved in anxiety and fear but also in the generation of post-traumatic stress disorder (i.e. PTSD). Amygdala is part of the limbic system and modulates the neuroendocrine and the autonomous nervous system activity. Behavioural changes to critical illness has been poorly studied in ICU-admited patients, despite studies showing that non-adapted corticotropic axis or autonomic nervous system responses correlate with a higher mortality or organ failures. During their ICU stay, patients are at high risk of developing psychological (e.g. anxiety, depression or PTSD), and cognitive alterations (e.g. memory and executive functions) with a major impact on their long-term quality of life. Such alterations intensity is correlated with the severity of critical illness. Our present work aimed, on the one hand at assessing at ICU admission patients’ anxiety and its prognostic value, and on the other hand, at characterizing the link between amygdalar activation and PTSD in a murine model of caecal ligation and puncture (i.e. CLP). 354 patients were included in our observational study (median age 63 [IQR 49-73], sex 137W/217M), from 3 Ile-De-France ICU between January 2014 and September 2016). Median anxiety was moderate according to both visual scale (4 [1-6]) and STAI questionnaire (43[32-53]). Half of participants declared (54%) feeling vulnerable; considered their state to be severe (67%) and feared to die (45%). One organ failure – mostly neurological, but also the need for mechanical ventilation, dialysis or vasopressive catecholamines during the first 7 days – was present in 157 (45%) patients. A STAI index ≥ 40 (OR 4.93 ; 95% CI[1.02 – 2.84]) was associated with the occurrence of an organ failure, even after adjusting for the day-1 SOFA score, the onset of a mechanical ventilation (OR 4.93, 95CI [2.9 – 9.4]), the Knaus score of prior pathologies severity (OC 2.01, 95CI [1.21 – 3.33]) and fear of death. (OR 0.55 [0.33 -0.92]). The latter significantly associating with a decreased risk of organ failure among patients with a severe acute pathology as defined by a IGS-2 >30 (58% vs. 37%). This study shows that evaluating early anxiety can prove useful in predicting patient aggravation risk in ICU, but also indicates that if its intensity positively predicts the onset of organ failures, the lack of perceived severity (lower fear of death) would also associate with an increased risk of failure. Our experimental study higlighted an early (i.e. 6H post CLP) and transitory activation of Central Amygdala (CeA) CAMK-II positive neurons, and delayed (i.e D15 post CLP) alterations in open field and fear-conditioning tests, respectively indicating an anxious behaviour and fear hypermnesia, both critical aspects of PTSD. Pharmacogenetic inhibition of CAMK-II neurons by viral transduction led to a decrease in aversive sepsis-induced hypermnesia. Administration of Levetiracetam, an antipeileptic drug, during the first 24h post-CLP led to a decrease in sepsis-induced mortality, in CAMK-II CeA neurons activation and in aversive memory. Amygdalar neuronal activation was also associated with microglial morphological alterations, partly prevented by levetiracetam, and reminiscent of alterations seen in septic shock autopsic samples. Our experimental work shows an increased activity in CAMK-II amygdalar neurons during early sepsis, potentially implicated in the onset of sepsis-induced anxiety and PTSD. this constitutes a plausible neuro-anatomical and neuro-biological background to our clinical study showing the prognostic interest of early anxiety assessment in ICU patients, as it positively correlates with both stress intensity and the misperception of danger.

Introdução: o crack é uma forma extremamente aditiva de cocaína, provocando intensa fissura e um comportamento persistente e intenso de busca pela droga com negligência da alimentação. A alimentação insuficiente pode levar à carência de tiamina. O uso de latas e folhas de alumínio na confecção de cachimbos para o consumo de crack aumenta a exposição de usuários de crack a este metal. Deficiência de tiamina somada a acúmulo cerebral de alumínio pode inibir o metabolismo energético dependente da glicose, levando à neurodegeneração e, possivelmente, à encefalopatia de Wernicke. Objetivos: avaliação dos níveis sanguíneos de tiamina difosfato e de alumínio de dependentes de crack e comparação com os de controles. Método: estudo transversal controlado, avaliou 35 dependentes de crack e 35 controles, do sexo masculino, com 18 anos ou mais. Os casos foram recrutados entre pacientes internados na Unidade de Adição do Hospital de Clínicas de Porto Alegre ou na Emergência em Saúde Mental IAPI, os controles foram recrutados entre as pessoas que circulam na área ambulatorial do Hospital de Clínicas de Porto Alegre. Todos participantes tiveram seu peso e estatura medidos e sangue coletado para determinação dos níveis de tiamina difosfato e de alumínio. Os casos passaram, também, por uma breve avaliação neurológica. Resultados: as características dos casos são semelhantes à amostra do principal estudo nacional sobre o uso de crack no Brasil: sexo masculino, cerca de 30 anos de idade, com baixa escolaridade, desempregados, usuários de múltiplas substâncias psicoativas, consumidores de crack há aproximadamente 8 anos. O índice de massa corporal dos casos foi significativamente mais baixo (p<0.0001). Seis casos (17.65%) apresentaram índice de massa corporal abaixo do normal. Dois casos apresentaram nível de tiamina abaixo dos valores de referência, enquanto os níveis dos controles estavam acima deste limite. Comparando os resultados do primeiro quartil do nível sanguíneo de tiamina dos casos (N= 9; mediana 3.6μg/dL, amplitude interquartil 3.05μg/dL -4.10μg/dL) com o dos controles (N=14, mediana 4.3μg/dL, amplitude interquartil 3.7μg/dL-4.4μg/dL), os casos apresentaram níveis significativamente mais baixos (p=0.024). Os níveis de alumínio dos casos que tiveram as amostras de sangue coletadas até 24h após o último consumo da substância, foram maiores (mediana1.85μg/L, amplitude interquartil0.65-4.425μg/L) que os dos controles (mediana 0.95μg/L, amplitude interquartil 0.7-1.22μg/L), mas esta diferença não atingiu significância estatística (p=0.07). Conclusões: dependentes de crack tem índice de massa corporal menor e estão mais expostos ao alumínio que os controles. Alguns tem deficiência de tiamina, a qual pode levar à encefalopatia de Wernicke e declínio cognitivo. Portanto, tiamina parenteral profilática deve ser considerada para alguns dependentes de crack. / Background: Crack-cocaine is an extremely additive form of cocaine and its compulsive use can last days until exhaustion, driving its users to neglect feeding. Poor feeding may cause thiamine deficiency. In Brazil, crack-cocaine is usually smoked in pipes made of aluminum cans or with aluminum foils. Insufficient brain levels of thiamine plus brain aluminum accumulation, may impair glucose energy metabolism, promoting neurodegeneration and possibly Wernicke’s encephalopathy. Objectives: The aim of this study was to evaluate thiamine and aluminum blood levels in crack-cocaine addicts and compare them to healthy controls. Methods: cross-sectional controlled study, included 35 crack-cocaine addicts and 35 healthy controls, all males, 18 or older. Cases were recruited at the Addiction Unit of Hospital de Clínicas de Porto Alegre or at the Mental Health Emergency IAPI, controls were recruited between people circulating in the outpatient clinic area of Hospital de Clínicas de Porto Alegre. Weight and height were measured and blood samples collected for determination of thiamine diphosphate and aluminum levels. Cases were also submitted to a brief neurological examination. Results: cases characteristics were similar to the sample of the main national study related to crack-cocaine use in Brazil: mainly males, about 30 years old, with low education level, unemployed, multiple drug abusers, consuming crack-cocaine for approximately 8 years. Body mass index was significantly lower in cases (p<0.0001). Six cases (17.65%) had body mass index lower than normal, while no control was below this limit. Two cases presented thiamine levels below the laboratory reference range, while controls were all above this limit. Comparing the lower quartile of thiamine blood levels, cases (3.6 μg/dL) had significantly lower levels of thiamine than controls (4.3μg/dL) (p=0.024). Blood aluminum median of crack-cocaine addicts (1.85μg/L, interquartile range 0.65-4.425μg/L) whose samples were drawn until 24h after last drug consumption was higher than controls (0.95μg/L, interquartile range 0.7-1.22μg/L), but the difference did not achieve statistical significance (p=0.07). Conclusions: Crack-cocaine addicts have lower BMI and are more exposed to aluminum in comparison to healthy controls. Also, some of them have thiamine deficiency which may lead to Wernicke’s encephalopathy and cognitive impairment. Thus, prophylactic parenteral thiamine should be considered to some crack-cocaine addicts.

Abstract Novel genetic aetiologies for epileptic encephalopathies and movement disorders have been discovered by using next-generation sequencing methods. The phenotypic and genotypic variability in these conditions is very wide. The aim of this study was to discover novel genetic causes and phenotypes of childhood-onset drug-resistant epilepsy and epileptic or developmental encephalopathies that occur separately or together with movement disorders, and familial movement disorders. Furthermore, the use of whole-exome sequencing (WES) as a diagnostic tool in clinical practice was evaluated. Altogether, 12 children with undefined aetiology, who fulfilled the inclusion criteria, were included in the study. GABRG2 gene was identified as a genetic cause of epileptic encephalopathies. Novel GABRG2-associated phenotypes included progressive neurodegeneration, epilepsy in infancy with migrating focal seizures, and autism spectrum disorder. New pathogenic variants, GABRG2 p.P282T and p.S306F, were discovered. The pathogenic NACC1 variant caused focal epilepsy, developmental disability, bilateral cataracts, and dysautonomia. The novel phenotype associated with the NACC1 p.R298W variant included hyperkinetic movement disorder. SAMD9L was found to be the genetic cause for the familial movement disorder. The phenotype associated with the novel SAMD9L p.I891T variant was very variable. Neuroradiological findings included cerebellar atrophy and periventricular white matter changes. After publication of these results, SAMD9L was reported to be one of the most common genetic aetiologies of childhood bone marrow failure and myelodysplastic syndrome. The pathogenic homozygous MTR variant was found to cause early-onset epileptic encephalopathy that occurred together with movement disorder and haematological disturbances. Drug resistant seizures responded to cofactor and vitamin treatments. Whole-exome sequencing for 10 patients with drug-resistant epilepsy or epileptic or developmental encephalopathy provided a genetic diagnosis for two patients (20%). This study confirmed that, for epileptic encephalopathies and movement disorders in which the genetic causes and phenotypes are heterogeneous and sometimes treatable, WES is a useful tool for diagnostics and in the search for novel aetiologies, which might turn out to be more common than expected. / Tiivistelmä Uusien sekvensointimenetelmien käyttöönotto on mahdollistanut epileptisten enkefalopatioiden ja liikehäiriöiden uusien geneettisten syiden löytymisen. Näissä sairausryhmissä geenien ja ilmiasujen vaihtelevuus on suurta. Tutkimuksen tarkoituksena oli löytää uusia geneettisiä syitä ja ilmiasuja lapsuusiällä alkavissa vaikeahoitoisissa epilepsioissa ja epileptisissä tai kehityksellisissä joko itsenäisesti tai yhdessä liikehäiriön kanssa esiintyvissä enkefalopatioissa sekä perheittäin esiintyvissä liikehäiriöissä. Lisäksi selvitettiin eksomisekvensoinnin käyttökelpoisuutta kliinisessä diagnostiikassa näiden potilasryhmien kohdalla. Tutkimukseen osallistui yhteensä 12 sisäänottokriteerit täyttävää lasta, joiden sairauden syy oli jäänyt tuntemattomaksi. GABRG2-geenin mutaatiot aiheuttivat epileptisiä enkefalopatioita, joiden uutena ilmiasuna oli etenevä taudinkuva, johon liittyivät aivojen rappeutuminen, migroiva imeväisiän paikallisalkuinen epilepsia sekä autismikirjon häiriö. Tutkimuksessa löydettiin uusia GABRG2-mutaatioita: p.P282T ja p.S306F. NACC1-geenin mutaatio aiheutti epilepsian, kehitysvammaisuuden, molemminpuolisen kaihin ja autonomisen hermoston toiminnan häiriön. Hyperkineettinen liikehäiriö oli uusi NACC1 p.R298W -mutaatioon liittyvä ilmiasu. SAMD9L-geenin mutaatio aiheutti perheessä esiintyvän liikehäiriön. Neurologinen ja hematologinen ilmiasu olivat hyvin vaihtelevia. Aivojen kuvantamislöydöksiin sisältyi pikkuaivojen rappeutumista ja valkoisen aivoaineen muutoksia aivokammioiden ympärillä. Näiden tutkimustulosten julkaisemisen jälkeen SAMD9L-geenin mutaatioiden on todettu olevan yksi yleisimmistä perinnöllisistä luuytimen vajaatoiminnan ja myelodysplasian syistä. Homotsygoottinen MTR-geenin mutaatio aiheutti varhain alkaneen epileptisen enkefalopatian, liikehäiriön ja hematologisen häiriön. Kofaktori- ja vitamiini hoidot vähensivät epileptisiä kohtauksia, joihin tavanomainen lääkitys ei tehonnut. Geneettiset syyt ja ilmiasut ovat epileptisissä enkefalopatioissa ja liikehäiriöissä hyvin vaihtelevia, ja osaan on olemassa spesifi hoito. Eksomisekvensointi on käyttökelpoinen diagnostiikan ja uusien geneettisten syiden etsimisen apuna. Tässä tutkimuksessa eksomisekvensoinnin avulla kymmenestä potilaasta kahdelle (20%) saatiin varmistettua geneettinen diagnoosi.

Orientador: Fernando Gomes Romeiro / Resumo: Introdução: Os aminoácidos de cadeia ramificada (BCAA) são parte do tratamento da encefalopatia hepática (HE) e aumentam a perfusão cerebral. Como são compostos por três aminoácidos diferentes, as proporções de cada um variam nos ensaios clínicos, tornando difícil esclarecer qual substância está mais envolvida na perfusão cerebral e em outros parâmetros significativos. O objetivo deste estudo foi comparar os efeitos clínicos e de perfusão cerebral obtidos pela suplementação de leucina versus isoleucina para tratamento da HE. Métodos: Cinqüenta pacientes ambulatoriais com cirrose e HE foram randomizados para receber suplementos orais contendo 30 g de leucina ou isoleucina diariamente, por um ano. As avaliações clínicas e a avaliação nutricional foram realizadas bimestralmente. A Tomografia Computadorizada cerebral por emissão de fóton único (SPECT) e a cintilografia cerebral dinâmica foram realizadas pré-tratamento e em 1, 8 e 12 meses de suplementação. Vinte e sete indivíduos concluíram o estudo (16 com isoleucina e 11 com leucina). Resultados: O aumento da perfusão cerebral foi observado apenas no grupo isoleucina. O aumento foi documentado aos 8 meses de tratamento tanto pelo SPECT como pela cintilografia cerebral (p <0,001 e p = 0,05, respectivamente) e pelo SPECT no 12º mês (p <0,05). Foi associado a uma melhora significativa de HE em 8 e 12 meses neste grupo (p = 0,008 e 0,004, respectivamente), o que foi menos claro no grupo leucina (p = 0,313 e 0,055, respectivamente).... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

No description available.

Thesis (M.S.)--State University of New York at Binghamton, Department of Psychology, 2009. / Includes bibliographical references.

L’encéphalopathie hépatique (EH) se développe chez les patients atteints d’une maladie du foie et se caractérise par de nombreuses anomalies neuropsychiatriques. L’insuffisance hépatique aiguë (IHA) se caractérise par une perte progressive de l’état de conscience, par une augmentation rapide de l’œdème cérébral et une augmentation de la pression intracrânienne entraînant une herniation cérébrale et la mort. Plusieurs facteurs sont responsables du développement de l’EH mais depuis une centaine d’années, l’hyperammonémie qui peut atteindre des concentrations de l’ordre de plusieurs millimolaires chez les patients atteints d’IHA aux stades de coma est considérée comme un facteur crucial dans la pathogenèse de l’EH. La présente thèse comprend 4 articles suggérant l’implication de nouveaux mécanismes pathogéniques dans le développement de l’EH et de l’œdème cérébral associés à l’IHA et tente d’expliquer l’effet thérapeutique de l’hypothermie et de la minocycline dans la prévention de l’EH et de l’œdème cérébral: 1. L’IHA induite par dévascularisation hépatique chez le rat se caractérise par une augmentation de la production de cytokines pro-inflammatoires cérébrales (IL-6, IL-1, TNF-). Cette observation constitue la première évidence directe que des mécanismes neuro-inflammatoires jouent une rôle dans la pathogenèse de l’EH et de l’œdème cérébral associés à l’IHA (Chapitre 2.1, articles 1 et 2). 2. L’activation de la microglie telle que mesurée par l’expression de marqueurs spécifiques (OX42, OX-6) coïncide avec le développement de l’encéphalopathie (stade coma) et de l’œdème cérébral et s’accompagne d’une production accrue de cytokines pro-inflammatoires cérébrales (Chapitre 2.1, article 1 et 2). 3. Un stress oxydatif/nitrosatif causé par une augmentation de l’expression de l’oxyde nitrique synthétase et une augmentation de la synthèse d’oxyde nitrique cérébral participe à la pathogénèse des complications neurologiques de l’IHA (Chapitre 2.3, articles 3 et 4). 4. Des traitements anti-inflammatoires tels que l’hypothermie et la minocycline peuvent constituer de nouvelles approches thérapeutiques chez les patients atteints d’IHA (Chapitre 2.1, article 1; Chapitre 2.2, article 2). 5. Les effets bénéfiques de l’hypothermie et de la minocycline sur les complications neurologiques de l’IHA expérimentale s’expliquent, en partie, par une diminution du stress oxydatif/nitrosatif (Chapitre 2.3, article 3; Chapitre 2.4, article 4). / Hepatic encephalopathy (HE) contains a spectrum of neuropsychiatric abnormalities observed in patients with liver disease. A quick worsening of consciousness and increasingly growing cerebral edema, high intracranial pressure, which leads to cerebral herniation and death, are characteristics of acute liver failure (ALF). Multiple factors are found responsible for the development of HE, whereas, over 100 years, hyperammonia is considered the most crucial factor in defining the pathogenesis of HE in ALF, which can increase to millimolar concentrations in the brain at the coma stages of HE. The present thesis comprises 4 articles, which demonstrates new pathogenic mechanisms involved in the development of HE and cerebral edema in ALF, and elucidates part of the therapeutic mechanism of hypothermia and minocycline in the prevention of HE and cerebral edema during ALF. The major findings are listed below: (1) Experimental ALF leads to the increase in brain production of proinflammatory cytokines (IL-6, IL-1, TNF-α), and provides the first direct evidence that central inflammatory mechanisms play a role in the pathogenesis of the encephalopathy and brain edema in ALF (chapter 2.1 - article 1; chapter 2.1 - article 2). (2) Activation of cerebral microglia, measured by OX-42, OX-6, predicts the presence of severe encephalopathy (coma) and brain edema in rats with ischemic ALF, which accompanies the increased production of brain proinflammatory cytokines (chapter 2.1 - article 1; chapter 2.2 - article 2). (3) Oxidative/nitrosative stress participates in the pathogenesis of brain edema and its complications in experimental ALF animals with ischemic liver failure. The increases in cerebral NOS isoform expression caused by ALF were sufficient to cause increased NO production in the brain (chapter 2.3 - article 3; chapter 2.4 - article 4). (4) Anti-inflammatory treatment, such as hypothermia or antibiotics, may be beneficial in patients with ALF (chapter 2.1 - article 1; chapter 2.2 - article 2). (5) The beneficial effect of both hypothermia and minocycline on the neurological complications of experimental ALF is mediated, at least in part, by reduction of brain-derived oxidative/nitrosative stress (chapter 2.3 - article 3; chapter 2.4 - article 4).

No description available.

The closure of the US border to Canadian live cattle and beef products after the confirmation of a single Canadian BSE case in May, 2003 seriously jeopardized the Canadian beef cattle industry, which had relied heavily on exports. The inventory of cattle rapidly increased and farmers were paid record low prices for live cattle. But at the same time, the cattle slaughtering industry experienced a substantial increase in profits. The enlarged price spread between the value of live cattle and beef steak raised concerns about oligopsony market power in the live cattle market. This thesis investigates the hypothesis that the Canadian slaughtering industry exercised this market power in the months following the discovery of BSE. Two models, the conjectural variation model from the New Empirical Industrial Organization and an asymmetric price transmission model were used and the results from both models do not support the hypothesis of oligopsony market power.