京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22505号 / 農博第2409号 / 新制||農||1077(附属図書館) / 学位論文||R2||N5285(農学部図書室) / 京都大学大学院農学研究科食品生物科学専攻 / (主査)教授 保川 清, 教授 宮川 恒, 教授 入江 一浩 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Orientador: Antonio Francisco Godinho / Resumo: O herbicida atrazina (ATR) é um praguicida usado intensivamente na agricultura, que persiste no meio ambiente e causa toxicidade em espécies não-alvo, inclusive seres humanos. Considerando o potencial da ATR para produzir efeitos no sistema nervoso central (SNC) e a falta de informações na literatura corrente sobre esse tipo de toxicidade, o objetivo deste projeto de pesquisa foi avaliar os efeitos da exposição subcrônica ao herbicida ATR sobre parâmetros neurocomportamentais específicos e estabelecer sua correlação com o estresse oxidativo (EO) em tecido cerebral de ratos e com o sistema dopaminérgico em regiões específicas do cérebro, nominalmente córtex pré-frontal (CPF), hipocampo (HIP) e corpo estriado. Ratos Wistar machos receberam solução salina (0,3 ml; controle - Ct), atrazina (ATR; 100 mg/kg), atrazina mais vitamin E (ATR; 100 mg/Kg + VE; 200 mg/kg), apenas vitamina E (VE; 200 mg/kg), atrazina mais levodopa (ATR; 100 mg/Kg + LEV; 20 mg/kg) e apenas levodopa (LEV; 20 mg/kg), por gavage, durante 28 dias. O comportamento foi avaliado utilizando arena de campo aberto (ACA), labirinto em cruz elevado (LCE) e hole-board (HB). O teste de estresse oxidativo no tecido cerebral avaliou os níveis de malondialdeído (MDA), capacidade antioxidante hidrofílica (CAH) e atividade das enzimas superóxido dismutase (SOD) e catalase (CAT). A dopamina (DA) foi quantificada por HPLC, em áreas cerebrais específicas (CPF, HIP e estriado). Exposição à ATR provocou ansiedade, diminuiu a coord... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Atrazine (ATR) herbicide is a pesticide used intensively in agriculture that persists in environment and causes toxicity on non-target species, include humans. Considering the potential of ATR to produce effects on the central nervous system (CNS) and the lack of information in the current literature about this type of toxicity, the aim of this research project was to evaluate the effects of subchronic exposure to ATR herbicide on specific neurobehavioral parameters and to establish its correlation with oxidative stress (OE) in rat brain tissue and with the dopaminergic system in specific brain regions, nominally prefrontal cortex (PFC), hippocampus (HIP) and striatum. Male Wistar rats received saline (0.3 ml; control - Ct), atrazine (ATR; 100 mg/kg), atrazine plus vitamin E (ATR; 100 mg/Kg + VE; 200 mg/kg) only vitamin E (VE; 200 mg/kg), atrazine plus levodopa (ATR; 100 mg/Kg + LEV; 20 mg/kg) and only levodopa (LEV; 20 mg/kg), via gavage, during 28 days. Behavior was assessed using open field arena (OF), elevated plus-maze (EPM) and hole-board (HB) apparatus. Oxidative stress assay in brain tissue evaluated malondialdehyde (MDA) levels, hydrophilic antioxidant capacity (HAC), and superoxide dismutase (SOD) and catalase (CAT) enzymes activity. Dopamine (DA) was quantified using HPLC, in specific brain areas (PFC, HIP and striatum). ATR exposure caused anxiety-like behavior, decreased motor coordination and did not alter the locomotor activity of the animals. ATR did not chang... (Complete abstract click electronic access below) / Doutor

The amino acid, 6-hydroxydopa (6-OHDOPA), found at the active site of amine oxidases, exists as a keto-enol. Exogenously administered 6-OHDOPA is an excitotoxin like β-N-oxalylamino-L-alanine (BOAA) and β-N-methylamino-L-alanine (BMAA), acting at the non-N-methyl-D-aspartate (non-NMDA) α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor. BMAA and BOAA are causal factors of neurolathyrism in humans. Much exogenously administered 6-OHDOPA is biotransformed by aminoacid decarboxylase (AADC) to the highly potent and catecholamine-(CA) selective neurotoxin, 6-hydroxydopamine (6-OHDA). 6-OHDOPA destroys locus coeruleus noradrenergic perikarya and produces associated denervation of brain by norepinephrine-(NE) containing fibers. Opiopeptides and opioids enhance neurotoxic effects of 6-OHDOPA on noradrenergic nerves, by a naloxone-reversible process. An understanding of mechanisms underlying neurotoxic effects of 6-OHDOPA can be helpful in defining actions of known and newfound amino acids and for investigating their potential neurotoxic properties.

Background: Bupivacaine is an amide type local anesthetic which is widely used for epidural anesthesia and nerve blockade in patients. However, local administration of bupivacaine could cause neuron injury showing transient neurologic symptoms. α-Lipoic acid (LA) was shown to protect nerve cells from substance-induced injury. We hypothesized that LA administration could attenuate bupivacaine-induced neurotoxicity. Methods: To evaluate our hypothesis, we treated mouse neuroblastoma N2a cells with LA 30 min before the cells were exposed to bupivacaine. We evaluated cellular injury by examination of cell viability, morphology changes, nuclear condensation, and Annexin V staining. We also examined the levels of intracellular reactive oxygen species (ROS) and activation of PI3K/Akt signaling pathway. In a separate experiment, we determined the effect of Akt inhibition on cell viability in the presence of LA and bupivacaine. Results: Bupivacaine treatment significantly induced cell injury as evidenced by decreased cell viability, increased nuclear condensation and Annexin V staining. Administration of LA significantly attenuated bupivacaine-induced cell injury. In addition, LA treatment increased the levels of phospho-Akt and phospho-GSK3β and attenuated bupivacaine decreased the levels of ROS. More significantly, pharmacological inhibition of Akt abolished the LA-induced protection from bupivacaine-caused cell injury. Conclusions: Our findings suggest that pretreatment of neuroblastoma cells with LA protected neural cells from bupivacaine-induced injury. The mechanisms involve activation of the PI3K/Akt signaling pathway.

In translational research, disease models in preclinical studies are used as media for discovery of drugs or novel therapeutics. Development of in vitro models for various neurological diseases that enable efficient pharmacological or toxicological screening has been ongoing but challenging. Recognizing the potential benefit of in vitro disease models, dysfunctions in the cortical neuronal networks were induced to mimic the functional pathology of neurological symptoms using microelectrode arrays. Two different disease states – tinnitusand excitotoxicity – were investigated and discussed. In this model, pentylenetetrazol-induced increase in spontaneous firing rate and synchrony in the auditory cortical networks was used as correlate of tinnitus. Potential tinnitus treatment drugs from several different classes – including the novel class of potassium channel openers – were screened and quantified. The potentialtherapeutic values of these drugs were also discussed as the basis for drug repurposing. Functional excitotoxicity was induced by cisplatin (a cancer drug that causes neurological sideeffects) and glutamate (the major excitatory neurotransmitter). As proof-of-principle that the model may contribute to expediting the development of therapeutics, cisplatin excitotoxicity wasprevented by the antioxidant D-methionine, while glutamate excitotoxicity was prevented by ceftriaxone (a modulator of a glutamate reuptake transporter). In the latter part of the study, with results linking two of the screened drugs L-carnitine and D-methionine to GABAA receptor activation, it was demonstrated that this model not only served as an efficient drug-screening platform, but can be utilized to functionally investigate the underlying mechanism of drugs. Inaddition, several practical or conceptual directions for future studies to improve on this in vitro disease model are suggested.

Medulloblastoma is the most frequent malignant brain tumor in children. During the last decades, the therapeutic landscape has changed significantly with craniospinal irradiation as the backbone of treatment. Survival times have increased and treatments were stratified according to clinical and later molecular risk factors. In this review, current evidence regarding the efficacy and toxicity of radiotherapy in medulloblastoma is summarized and discussed mainly based on data of controlled trials. Current concepts and future perspectives based on current risk classification are outlined. With the introduction of CSI, medulloblastoma has become a curable disease. Due to combination with chemotherapy, survival rates have increased significantly, allowing for a reduction in radiation dose and a decrease of toxicity in low- and standard-risk patients. Furthermore, modern radiotherapy techniques are able to avoid side effects in a fragile patient population. However, high-risk patients remain with relevant mortality and many patients still suffer from treatment related toxicity. Treatment needs to be continually refined with regard to more efficacious combinatorial treatment in the future.

INTRODUCTION: Multiple myeloma (MM) is a disease that results in the production of ineffective immunoglobulins and monoclonal proteins in the blood and urine, leading to insufficient organ function or death. Currently, there is a 5-year survival rate of 47% for patients diagnosed with MM, with a proportion of patients ultimately succumbing to the disease. The current standard of care for MM includes toxic combinations of chemotherapy. The evolution of chimeric antigen receptor (CAR) T-cell therapy for hematologic cancers such as lymphoma, leukemia, and now myeloma has provided another effective treatment option for patients who have relapsed after standard treatments for MM. Idecabtagene Vicleucel (ide-cel), was approved in March 2021 for patients with relapsed and refractory MM. While CAR T-cell treatment appears to be far less toxic than standard chemotherapy, this therapy comes with its own associated toxicities, mainly cytokine release syndrome (CRS) and neurotoxicity (NT). In clinical trials, ide-cel demonstrated to be an effective treatment in some patients, leading to the FDA approval for patients who have exhausted multiple other lines of therapy. Currently, it is unclear why patients respond differently to CAR T-cell treatment and why some patients present with more severe toxicity than others. Therefore, this study aims to examine patient factors such as demographics, age, and treatment history to determine if such characteristics may influence the CAR T-cell response; also, we assess the efficacy of ide-cel in a real-world experience outside of a clinical trial. METHODS: In this study, 14 patients’ medical records were reviewed after receiving commercial CAR T-cell therapy between August 2021 and January 2022. Eligible patients for the therapy were determined by strict inclusion criteria, including having a confirmed diagnosis of MM and exhausting at least four prior lines of therapy, as well as exclusion criteria, such as excluding individuals who have received CAR T-cells prior in a clinical trial setting. Approximately one month before preparation lymphodepletion chemotherapy, eligible patients underwent leukapheresis and had their blood sent to a laboratory to extract T-cells and genetically modify them to express the CAR for reinfusion. On 3 and 5 days prior to CAR T-cell infusion, patients underwent lymphodepletion using fludarabine and cyclophosphamide. Patients remained in the hospital for approximately one week following infusion, pending adverse reactions. After discharge, patients returned to the hospital for routine follow-ups. Data analysis was then performed on collected clinical readouts such as: prior treatments, bone marrow biopsies, response rates, laboratory values from blood samples, and pre- and post-infusion scans of various tissues within the body. RESULTS: At a median follow-up time of 15 weeks, six patients (43%) achieved a complete response (CR), three patients demonstrated a partial response (PR, 21%), and four patients showed disease progression (PD, 28%). Post-infusion scans were not available for one subject (7%) as they were still in the hospital. These results are similar to the phase I and phase II trials in which 45% and 33% of patients demonstrated a CR post-infusion, respectively. As for associated toxicities, 10 patients (71%) experienced CRS and one patient (7%) presented with ICANS. All patients that achieved a CR experienced ide-cel related toxicities, compared with only 38% of those with less favorable or unknown outcomes, which indicates that systemic immune system activation which causes CRS may be required to achieve a CR but CRS is not always linked with a CR outcome. There were 28 different chemotherapy regimens used as the standard of care treatment prior to ide-cel therapy. We assessed the most recent chemotherapeutic regimen in each patient to assess whether there is an association with most recent treatment and response. Of the six patients that achieved a CR to ide-cel, all were previously treated with RVD or CyBorD regimens, compared to the four patients who had disease progression who were mainly treated with salvage DCEP chemotherapy. Four patients (29%) received DCEP as their final chemotherapy regimen, and 3 of these 4 (75%) demonstrated progressive disease after ide-cel. Two patients received Belantamab-Mafodotin prior to ide-cel treatment, with one patient presenting with disease progression and the other patient achieving CR. 71% of patients experienced CRS following ide-cel infusion, which is resembles the phase II trial of ide-cel in which 84% of patients demonstrated CRS. In this study, only 7% of patients experienced neurological toxicity, which is comparable to the 18% of patients that demonstrated to have ICANS in the phase II study. CONCLUSIONS: We found similar performance of the ide-cel CAR-T therapy in the real world setting as in the clinical trial. Also, the complete responses were achieved by subjects with an array of characteristics, including varying recent chemotherapeutic treatments, IgG, IgA, and light-chain only subtypes of MM, and diverse demographics and other characteristics. The characteristic that demonstrated the most predictability and somewhat unique to subjects with CR was the associated toxicities from ide-cel. Development of these associated toxicities may attest that substantial immune activation, of CAR T-cells and other immune cells, leads to the efficacy of the product in eliminating cancer cells. Further analysis will need to be completed as more individuals enroll in this study to be able to determine if there are significant associations between demographics and prior lines of treatment with response to ide-cel CAR-T therapy. Lastly, future studies should assess the immune cell effector functions that are generated in CR patients that will help to specify the association between ide-cel activation, experienced associated toxicities, and its efficacy.

A recent chemical spill of 4-Methylcyclohexanemethanol (4-MCHM) in West Virginia left 300,000 people without water. Officials claimed that this compound is not lethally toxic, but potentially harmful if swallowed or inhaled, and can cause eye and skin irritation. Sittig's Handbook of Toxic and Hazardous Chemical Carcinogens reports high exposures from skin contact or inhalation may cause damage to the heart, liver, kidneys, and lungs, and may result in death. However, no quantitative data seem to exist and no references can be found on neurotoxicity. We have investigated the neurotoxicity of 4-MCHM using mammalian nerve cell networks grown on microelectrode arrays. Network spontaneous activity from multiple units (range 48 – 120 per network) were used as the primary readout. Individual units were followed based on spike waveforms digitized at 40 kHz (Plexon MNAP system). Dose response curves show the effective inhibitory concentration at 50 percent decrease (EC50) to average 27.4 microM SD±6.17. However, in the presence of 40 microM bicuculline, a competitive GABAA antagonist, the EC50 shifts to 70.63uM SD ±4.3; implying that early, low concentration exposures to 4-MCHM involve GABA activation. Initial activity loss occurs without active unit loss (defined as 10 or more template threshold crossing per min), indicating functional interference with spike production. Full recovery has not been seen at concentrations above 130 microM, unless the culture was given bicuculline. Direct exposure to 400uM results in immediate, irreversible loss of spike production, followed by necrosis of glia and neurons.

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