Over 15 million contact sports players and military veterans are at risk for the development of chronic traumatic encephalopathy (CTE), a neurodegenerative disease associated with exposure to repetitive head impacts (RHI) that sometimes presents with parkinsonian motor symptoms, although very little is understood about how these individuals develop parkinsonism. CTE is characterized by accumulation of hyperphosphorylated tau protein (p-tau), and diagnosis requires the presence of neuronal tau in the form of neurofibrillary tangles at the depth of cortical sulci. We performed quantitative immunoassays for markers of neurovascular inflammation within the postmortem dorsolateral frontal cortex of participants with and without a history of RHI and CTE (n = 156), and tested for associations with RHI, microgliosis, and tau pathology measures. Levels of vascular injury-associated markers were increased in CTE compared to RHI-exposed and -naïve controls. Markers increased with RHI exposure duration and were associated with increased microglial density and tau pathology. Histologically, there was significantly increased ICAM1 staining of the microvasculature, extracellular space, and astrocytes at the sulcal depths in high stage CTE compared to both low stage CTE and controls. Multifocal perivascular immunoreactivity for serum albumin was present in all RHI-exposed individuals. These findings demonstrate that vascular injury markers are associated with RHI exposure, duration, and microgliosis, are elevated in CTE, and increase with disease severity. We next performed a cross-sectional analysis of all brain donors with CTE and without comorbid neurodegenerative disease (n=495) in the UNITE Brain Bank. Participants with parkinsonism (CTE-p, n=119) had a higher mean age at death (71.5 years (y)) than participants without parkinsonism (CTE-np, n=362, 54.1 y) and exhibited a higher rate of dementia than CTE-np participants. CTE-p participants had a more severe CTE stage and nigral pathology (NFTs, neuronal loss, and more frequent Lewy bodies), though the majority of cases were negative for nigral Lewy bodies. In American football players, simultaneous regression analysis demonstrated that nigral NFTs and neuronal loss mediate a connection between years of play and parkinsonism in CTE. In this cross-sectional study of contact sports athletes with CTE, years of contact sports participation was associated with SN proteinopathy and neuronal loss, and these pathologies were associated with parkinsonism. Finally, in a postmortem cohort (n=392) of brain donors with CTE without comorbid neurodegenerative disease, we used linear regression modelling to analyze the associations between isodendritic core nuclei pathology (semiquantitative neurofibrillary tangles (NFTs), neurites, and neuronal loss scores) and CTE disease severity, RHI exposure duration (years of contact sport play), and informant-reported cognitive and daily function as assessed by the Cognitive Difficulties Scale (CDS) and Functional Activities Questionnaire (FAQ), respectively. Overall, isodendritic core (IC) NFT scores increase with disease stage, Initially in the locus coeruleus and finally in the median raphe nuclei. Neuronal loss occurred at later disease stages than NFT accumulation. RHI exposure was associated with p-tau pathology for all IC regions. NFTs and neuronal loss in the substantial nigra were associated with increased CDS scores (i.e., worse cognitive function), and neuronal loss in the substantia nigra and locus coeruleus were associated with increased FAQ scores (i.e., worse daily function). We are able to show CTE is similar in distribution of p-tau pathology to progressive supranuclear palsy (PSP), a disease that is thought to primarily affect subcortical regions, especially by end stage disease. These results demonstrate the vulnerability of the isodendritic core nuclei to p-tau pathology and neuronal loss in CTE, and suggest that their involvement contributes to cognitive and functional symptoms during life. This work highlights the possible linkage between neuroinflammation leading to nigral p-tau accumulation and neuron loss which likely underlies the development and progression of parkinsonian motor symptoms in CTE.

Ganglion cell death in glaucoma is caused by a variety of insults that include ischemia, insufficient neurotrophic support and oxidative stress. Experimental studies were therefore conducted on cell cultures to determine how serum deprivation (to mimic insufficient neurotrophic support) or oxidative glutamate toxicity (GB), cause oxidative stress and induce retinal cell death. Moreover, studies were carried out to deduce whether selected sulphur containing compounds can blunt any negative influences to cells in culture and/or a defined ischaemic insult to the rat retina in situ, as this might suggest their use for the treatment of glaucoma. Serum deprivation and GB caused generation of reactive oxygen species (ROS) and apoptosis-like death to transformed retinal ganglion cells (RGC-5 cells). RGC-5 cells were more susceptible to the detrimental effects of GB than serum deprivation. RGC-5 cells subjected to serum deprivation appear to die by mechanisms that resemble classical apoptosis more closely than that caused by GB and the phase between the maximal generation of ROS and cell death were different. Cell death caused by serum deprivation was caspase-dependent but this was not the case for GB. Moreover, of the two sulphur compounds sulbutiamine and N-acetyl cysteine (NAC), sulbutiamine blunts the effect of serum deprivation more effectively. In addition, the pan caspase inhibitor z-VAD-fmk attenuated the negative effect of serum deprivation to RGC-5 cells while the necroptosis inhibitor (necrostsatin-1) counteracted solely the insult of GB. The sulphur containing compounds, ACS1 and ACS 67 which release hydrogen sulphide (H2S) slowly and NAC (a pro-cysteine GSH precursor) attenuated GB-induced cell death of RGC-5 cells. In contrast, sulbutiamine (a lipophilic thiolic thiamine derivative) was particularly effective in protecting RGC-5 cells from an insult of serum deprivation. Moreover, all of the sulphur compounds directly sequestered different types of ROS but with varying efficiency. Common features by which all tested sulphur containing agents seem to elicit a mode of action include the stimulation of GSH and the antioxidant enzyme glutathione-S-transferase (GST) as well as to scavenge excess free radicals. Moreover, the slow release of H₂S from the ACS compounds appears to protect cells from oxidative stress through increasing the level of GSH, modulation of the cystine uptake transporter xCT, stimulation of the oxidative stress related transcription factor Nrf2 and the stimulation of pro-survival signalling pathways. The slow releasing H₂S sulphur compound ACS67 also counteracts a number of detrimental influences to the rat retina in situ because of ischemia/reperfusion that includes damage to their ganglion cells. This suggests that such sulphur compounds might find a use in the treatment of glaucoma where ischemia probably plays a part in the disease process.

Despite a comprehensive mapping of the Parkinson's disease (PD)-related mRNA and protein leucine-rich repeat kinase 2 (LRRK2) in the mammalian brain, its physiological function in healthy individuals remains enigmatic. Based on its structural features and kinase properties, LRRK2 may interact with other proteins involved in signalling pathways. Here, we show a widespread LRRK2 mRNA and/or protein expression in expanded or differentiated human mesencephalic neural progenitor cells (hmNPCs) and in post-mortem substantia nigra PD patients. Using small interfering RNA duplexes targeting LRRK2 in hmNPCs following their differentiation into glia and neurons, we observed a reduced number of dopaminergic neurons due to apoptosis in LRRK2 knockdown samples. LRRK2-deficient hmNPCs exhibited elevated cell cycle- and cell death-related markers. In conclusion, a reduction of LRRK2 expression in hmNPCs severely impaired dopaminergic differentiation and/or survival of dopaminergic neurons most likely via preserving or reactivating the cell cycle.

Neurodegenerative disorders (NDD) are an ever-increasing burden on healthcare; consequently, elucidating the mechanisms underlying neurodegeneration (ND) is critical for the development of effective treatments for these diseases. In order to unravel the molecular pathways underlying movement disorders and identify new genes involved in ND, two ataxic mouse mutants characterised by cell death in the cerebellum were studied in detail using a combination of in vitro and in vivo techniques. The robotic mouse demonstrated the key role of a transcription factor, Af4, in Purkinje cell (PC) survival and how only small changes in the levels of a single transcriptional cofactor could deleteriously affect normal cerebellum function. Expression array studies of the robotic PCs revealed the first confirmed targets of Af4-mediated transcription, including insulin-like growth factor 1 (Igf-1). It was demonstrated that Igf-1 is critical for PC survival, highlighting the role of the IGF-1 signalling pathway as a potential therapeutic target for the treatment of cerebellar ataxia in humans. Detailed analysis of the bella mutant demonstrated that ataxia and apoptotic cerebellar degeneration is caused by loss of the oxidative resistance 1 (Oxr1) gene. In vitro modelling experiments went on to show that the levels of this previously uncharacterised gene are critical for controlling the sensitivity of neuronal cells to oxidative stress (OS). Moreover, this study showed that Oxr1 was up-regulated both in human and pre-symptomatic mouse models of amyotrophic lateral sclerosis (ALS), demonstrating that Oxr1 was an early marker of ROS defence, prior to pathology, and potentially a novel neuroprotective factor in NDD. Preliminary interaction studies show that Oxr1 is likely to be a multi-functional protein that forms complexes with proteins known to be mutated in NDD. Thus, the study of both the robotic and the bella mouse has demonstrated the value of the phenotype-driven approach to investigate novel neurodegenerative pathways.

Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) are the commonest motor neuron diseases of adult- and childhood onset. Alterations of the RNA binding protein TDP-43 are associated with most cases of ALS, while SMA is caused by deletion of the Survival Motor Neuron (SMN1) gene. SMN has been well characterised in its role in the assembly of the cellular machinery that carries out splicing of pre-mRNA, but is thought to have other functions in RNA metabolism unrelated to pre-mRNA splicing. It is conceivable that specific aspects of RNA handling are disrupted in both SMA and ALS. A variety of genetic, molecular and neuropathological approaches were applied to investigate a potential common pathway in these diseases. The spectrum of genetic mutations underlying motor neuron disorders were explored by screening patient DNA. Cell culture and mouse models were used to test the hypothesis that altered pre-mRNA splicing causes motor neuron death. Human neuropathological specimens were examined for changes in proteins involved in RNA metabolism. The results indicate that altered pre-mRNA splicing is a late occurrence in disease and more likely to be a consequence rather than the cause of motor neuron degeneration. However, the notion that RNA metabolism is highly relevant to motor neuron diseases was strengthened by the discovery of mutations in another RNA binding protein, FUS, in cases of ALS without TDP-43 pathology. Overall the findings highlight the need to consider disruption of mRNA transport and regulation of mRNA translation in future motor neuron disease research.

D-serine metabolism is implicated in schizophrenia pathophysiology. This is based on reduced D-serine levels in the disorder, its ameliorative effects therapeutically and the potential genetic contributions of its metabolic enzymes, D-amino acid oxidase (DAO) and serine racemase (SRR). D-serine is a gliotransmitter and the N-methyl D-aspartate receptor (NMDAR) co-agonist. Thus, altered D-serine metabolism may contribute to NMDAR hypofunction in schizophrenia. The research in this thesis was designed to investigate D-serine metabolic enzymes further through studying their distribution, their expression in schizophrenia and their effect on NMDARs. The regional and cellular distribution of DAO and SRR in rodent and human brain were investigated using immunohistochemistry. Both enzymes were found within frontal cortex, hippocampus and cerebellum. In rodent frontal cortex, SRR expression was neuronal suggesting D-serine is not always glia-derived. In the human this was not the case, highlighting possible species differences. DAO in the rodent and human cortex was robustly detected, challenging previous views. In rodent cerebellum, both enzymes were neuronal and glial and in human, predominantly glial. In schizophrenia, DAO and SRR expression were investigated using western blotting and real-time PCR. DAO expression was elevated in the cerebellum in the disorder, without an accompanying change in SRR. In the dorso-lateral prefrontal cortex (DPFC), DAO and SRR mRNAs were unchanged in schizophrenia but SRR protein was significantly increased. The elevation in DPFC SRR protein was not replicated however in a second study. To investigate the effects of D-serine metabolic enzymes on NMDARs, an in vitro model of altered SRR expression was developed, but its use hindered through technical complications. The data detailed demonstrate new findings of DAO and SRR’s distributions in the brain and highlight novel potential roles for these enzymes. In addition, the data provide some paradoxical findings including DAO’s cortical expression. The investigations in schizophrenia lend to robust demonstrations of DAO’s elevated cerebellar expression in the disorder. However, its roles therein and that of DAO and SRR on NMDAR function remain unclear.

The subthalamic nucleus (STN), which is the most common target for deep brain stimulation for Parkinson's disease, is known to be crucially involved in motor control. Recent appreciation of the potential non-motor side effects of STN deep brain stimulation, however, has led to speculation that the importance of this nucleus may also relate to processes involved in decision- making, particularly during high conflict scenarios. This thesis concerns itself with investigating the STN's role in action selection during conflict. I begin by recording local field potentials directly from the STN of Parkinson's disease patients while they perform a flanker task that has been shown to elicit theta (4-8 Hz) band activity in areas of the prefrontal cortex involved in cognitive control. I report that like the prefrontal cortex, the STN demonstrates elevated theta activity during conflict. I then test whether STN theta activity is related to that of the prefrontal cortex by recording from both sites simultaneously while patients perform a novel task that temporally separates conflict from stimulus onset or movement. This reveals that theta activity indeed becomes synchronized during conflict, with cortical oscillations driving those of the STN. Thirdly, I investigate how STN oscillations may affect firing rate dynamics by intra-operatively recording local field potentials and single unit activity from patients performing the flanker task. I report that both theta and beta (15-30 Hz) oscillations entrain STN neurons, but only during conflict. Finally, I record cortical and STN activity while a fourth group of patients performs the flanker task. This experiment confirms that cortico-STN theta synchrony is elevated during conflict and may also relate to across-trial adaptations to conflict and errors. Taken together these studies shed light on the mechanisms by which cortical structures may influence the STN during conflict and why STN deep brain stimulation may result in impulsivity.

Gastrointestinal (GI) alpha-synuclein (ASN) detection may represent a clinically useful biomarker of Parkinson's disease (PD), but this has been challenged by conflicting results of recent studies employing different immunohistochemical (IHC) methods and reporting diverse morphological patterns with variable biological interpretation. To increase sensitivity and specificity, we applied three different techniques to detect different possible conformations of ASN in GI tissue derived from biopsies of the GI tract, which were obtained from a longitudinally followed, clinically well-characterized cohort of PD subjects and healthy controls (HC) (Oxford Discovery study). With IHC, we used antibodies reactive for total (T-ASN-Abs), phosphorylated (P-ASN-Abs) and oligomeric (O-ASN-Abs) ASN; with the ASN Proximity Ligation Assay (AS-PLA), we targeted oligomeric ASN species specifically; finally, with the Paraffin-Embedded Tissue Blot (PET-Blot) we aimed to detect fibrillary conformations of ASN specifically. Optimisation and validation of the PET-Blot and PLA techniques was carried out with studies on brain tissue from subjects with ASN pathology, and these experiments were used to gain insight into morphology and distribution of different conformational variants of ASN in the brain of subjects with Lewy pathology. We specified all the detected morphological staining patterns with each technique interpreting them as pathologic or non-specific. Correlation to clinical symptoms was assessed to investigate the potential predictive or diagnostic value of specific staining patterns as biomarkers. A total of 163 GI tissue blocks were collected from 51 PD patients (113 blocks) and 21 healthy controls (50 blocks). In 31 PD patients, GI biopsies had been taken before PD diagnosis (Prodromal PD group); while in 20 PD patients biopsies were obtained after PD diagnosis (Manifest PD group). The majority of these tissues blocks were from large intestine (62%), followed by small intestine (21%), stomach (10%) and oesophagus (7%). With IHC, four ASN staining patterns were detected in GI tissue (Neuritic, Ganglionic, Epithelial, and Cellular), while two distinct staining patterns were detected with AS-PLA (cellular and diffuse signal) and with AS-PET-Blot (ASN-localised and peri-crypt signal). The level of agreement between different techniques was generally low, and no single technique or staining pattern was able to reliably distinguish PD patients (Prodromal or Manifest) from HC. Overall, our study suggests that even specific detection of ASN conformational variants currently considered pathologic was not adequate for the prediction of PD. Future studies with these or other novel techniques focusing on the upper part of the GI tract could overcome current limitations in sensitivity and specificity.

INTRODUÇÃO: Embora a mortalidade geral tenha diminuído na era da terapia antirretroviral de alta potência (TARVAP), o envolvimento do Sistema Nervoso Central (SNC) ainda é elevado nos pacientes com infecção pelo HIV. O estudo sobre possíveis correlações entre neuroinfecções, a presença de déficts neurocognitivos e o uso da TARVAP é importante para se avaliar os efeitos de longo prazo do tratamento com drogas antirretrovirais em uma população. Desta forma, são necessários estudos para se avaliar a neuropatologia da infecção pelo HIV e os efeitos do tratamento bem como a adesão ao mesmo. OBJETIVOS: Analisar a frequência e o tipo de infecções oportunistas e da infecção crônica pelo HIV no SNC na era pós-TARVAP, de pacientes necropsiados em um hospital universitário, no período de 2007 a 2014. Nestes casos, avaliar o substrato neuropatológico de pacientes com Aids e histórico clínico de demência. MATERIAIS E MÉTODOS: Foram analisados os achados dos exames neuropatológicos de 123 encéfalos de pacientes autopsiados com AIDS no Serviço de Patologia do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP/USP), seus dados clínicos e respectivos os laudos necroscópicos. RESULTADOS: Dos 123 casos analisados, 73 (59,3%) eram do sexo masculino e a média de idade foi de 40,56 anos. Destes, 69 (56,1%) tiveram neuroinfecções causadas por agentes oportunistas, sendo a neurotoxoplasmose a mais prevalente. Da correlação entre a contagem de células CD4 e o uso da TARVAP houve diferença significativa para uma delas, àquela que foi analisada como sendo a terceira mais próxima da data do óbito (p = 0,03). Apenas 6 pacientes fizeram uso regular da TARVAP no decorrer da doença e nenhum deles apresentaram neuroinfecções durante o tratamento. CONCLUSÕES: Podemos concluir que mesmo na era pós TARVAP as infecções no SNC causadas por agentes infecciosos permanecem presentes e no caso da população estudada podem estar correlacionadas com a baixa adesão ao tratamento. / RATIONALE: Although overall mortality has decreased in the era of highly active antiretroviral therapy (HAART), the involvement of the central nervous system (CNS) is still high in patients with HIV infection. The study of possible correlations between neuroinfections, the presence of neurocognitive payment deficits and the use of HAART is important to evaluate the long-term effects of treatment with antiretroviral drugs in a population. Thus, studies are needed to evaluate the neuropathology of infection by HIV and the treatment effects and it adhesion. OBJECTIVES: To analyze the changes caused by opportunistic infections and chronic HIV infection in the CNS in the post-HAART era of autopsied patients at a university hospital, from 2007 to 2014. In these cases, assess the neuropathologic of AIDS patients and clinical history of dementia. MATERIALS AND METHODS: The findings of neuropathological examinations of 123 brains of patients were analyzed autopsied AIDS in Hospital Pathology Service of the Clinics of Ribeirão Preto Medical School, University of São Paulo (HCFMRP / USP) clinical data and their postmortem reports. RESULTS: The 123 cases analyzed, 73 (59.3%) were male and the average age was 40.56 years. Of these 69 (56,1%) had neuroinfections caused by opportunistic agents, toxoplasmosis being the most prevalent. The correlation between CD4 cell count and use of HAART were no significant differences for one of them to that which was analyzed as being the closest third of the date of death (p = 0.03). Only 6 patients made regular use of HAART during the disease and none of them showed neuroinfections during treatment. CONCLUSIONS: We can conclude that even in the post HAART era CNS infections caused by infectious agents remain present and in the case of the studied population can be correlated with low adherence to the treatment.

INTRODUÇÃO: Embora a mortalidade geral tenha diminuído na era da terapia antirretroviral de alta potência (TARVAP), o envolvimento do Sistema Nervoso Central (SNC) ainda é elevado nos pacientes com infecção pelo HIV. O estudo sobre possíveis correlações entre neuroinfecções, a presença de déficts neurocognitivos e o uso da TARVAP é importante para se avaliar os efeitos de longo prazo do tratamento com drogas antirretrovirais em uma população. Desta forma, são necessários estudos para se avaliar a neuropatologia da infecção pelo HIV e os efeitos do tratamento bem como a adesão ao mesmo. OBJETIVOS: Analisar a frequência e o tipo de infecções oportunistas e da infecção crônica pelo HIV no SNC na era pós-TARVAP, de pacientes necropsiados em um hospital universitário, no período de 2007 a 2014. Nestes casos, avaliar o substrato neuropatológico de pacientes com Aids e histórico clínico de demência. MATERIAIS E MÉTODOS: Foram analisados os achados dos exames neuropatológicos de 123 encéfalos de pacientes autopsiados com AIDS no Serviço de Patologia do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP/USP), seus dados clínicos e respectivos os laudos necroscópicos. RESULTADOS: Dos 123 casos analisados, 73 (59,3%) eram do sexo masculino e a média de idade foi de 40,56 anos. Destes, 69 (56,1%) tiveram neuroinfecções causadas por agentes oportunistas, sendo a neurotoxoplasmose a mais prevalente. Da correlação entre a contagem de células CD4 e o uso da TARVAP houve diferença significativa para uma delas, àquela que foi analisada como sendo a terceira mais próxima da data do óbito (p = 0,03). Apenas 6 pacientes fizeram uso regular da TARVAP no decorrer da doença e nenhum deles apresentaram neuroinfecções durante o tratamento. CONCLUSÕES: Podemos concluir que mesmo na era pós TARVAP as infecções no SNC causadas por agentes infecciosos permanecem presentes e no caso da população estudada podem estar correlacionadas com a baixa adesão ao tratamento. / RATIONALE: Although overall mortality has decreased in the era of highly active antiretroviral therapy (HAART), the involvement of the central nervous system (CNS) is still high in patients with HIV infection. The study of possible correlations between neuroinfections, the presence of neurocognitive payment deficits and the use of HAART is important to evaluate the long-term effects of treatment with antiretroviral drugs in a population. Thus, studies are needed to evaluate the neuropathology of infection by HIV and the treatment effects and it adhesion. OBJECTIVES: To analyze the changes caused by opportunistic infections and chronic HIV infection in the CNS in the post-HAART era of autopsied patients at a university hospital, from 2007 to 2014. In these cases, assess the neuropathologic of AIDS patients and clinical history of dementia. MATERIALS AND METHODS: The findings of neuropathological examinations of 123 brains of patients were analyzed autopsied AIDS in Hospital Pathology Service of the Clinics of Ribeirão Preto Medical School, University of São Paulo (HCFMRP / USP) clinical data and their postmortem reports. RESULTS: The 123 cases analyzed, 73 (59.3%) were male and the average age was 40.56 years. Of these 69 (56,1%) had neuroinfections caused by opportunistic agents, toxoplasmosis being the most prevalent. The correlation between CD4 cell count and use of HAART were no significant differences for one of them to that which was analyzed as being the closest third of the date of death (p = 0.03). Only 6 patients made regular use of HAART during the disease and none of them showed neuroinfections during treatment. CONCLUSIONS: We can conclude that even in the post HAART era CNS infections caused by infectious agents remain present and in the case of the studied population can be correlated with low adherence to the treatment.