The incidence of childhood leukemia is increasing, especially in urbanized areas. It is hypothesised that transplacental exposure to environmental carcinogens, such as benzene, plays a role in the etiology of childhood cancers. The studies in this thesis investigated mechanisms of transplacental benzene tumourigenesis focusing on the role of reactive oxygen species (ROS). Initially, we investigated the effect of maternal benzene exposure on fetal erythroid progenitor cell number and the role of ROS in benzene metabolite-induced dysregulation of erythropoiesis. In the CD-1 mouse, in utero benzene exposure caused significant alterations in female fetal liver erythroid progenitor cell numbers at gestational day 16 and postnatal day 2. Using an in vitro chicken erythroblast cell line capable of erythropoiesis, we found that hydroquinone significantly inhibited erythropoiesis and this effect was prevented by pretreatment with PEG-superoxide dismutase. The second objective investigated the role of ROS in dysregulated fetal hematopoietic progenitor cell growth after maternal benzene exposure in C57Bl/6N mice. In utero exposure to benzene caused changes in fetal hematopoietic progenitor cell numbers, an increase in levels of fetal liver intracellular ROS, and a decrease in IκB-α protein levels, which were all prevented by pretreatment with PEG-catalase. The final objective determined the incidence of cancer in offspring transplacentally exposed to benzene. This study compared two strains of mice (C57Bl/6N and CD-1), as well as male and female offspring. This study also measured levels of benzene and benzene metabolites present in maternal blood and fetal liver tissue after maternal benzene exposure. Transplacental exposure to benzene induced hepatic and hematopoietic tumours in male and female CD-1 mice, respectively. Interestingly, there were no significant changes in tumour incidence in C57Bl/6N mice demonstrating a significant strain difference in susceptibility to transplacental benzene carcinogenesis. Levels of fetal liver benzene metabolites also differed between genders and strains of mice suggesting that the gender and strain differences in tumour formation may be dependent on fetal benzene metabolism capability. In conclusion, this thesis supports the hypothesis that benzene exposure to pregnant women contributes to the etiology of childhood cancers and highlights ROS and fetal benzene metabolism as potential mechanisms. / Thesis (Ph.D, Pharmacology & Toxicology) -- Queen's University, 2009-12-21 13:10:12.747

Benzene is an ubiquitous pollutant and industrial solvent that has been identified as a human leukemogen. Early exposure to environmental carcinogens such as benzene has been postulated to play a role in the etiology of childhood leukemia, however the association remains controversial. Genotoxic agents such as benzene can cause an increase in the frequency of DNA double-strand breaks, which may remain unrepaired or result in the initiation of DNA recombinational repair mechanisms. The first objective was to investigate the induction of DNA double-strand breaks following in utero treatment to 200 mg/kg and 400 mg/kg benzene i.p. using the phosphorylated histone γ-H2A.X as a marker. Using immunoblotting, treatment with benzene did not increase the formation of γ-H2A.X in bone marrow cells of adult C57Bl/6N male mice and in maternal bone marrow, fetal liver, and post-natal bone marrow cells following in utero exposure to 200 mg/kg or 400 mg/kg benzene throughout gestational days 7 to 15. Secondly, the study investigated the induction of micronuclei following in utero exposure to benzene. Acute exposure to 400 mg/kg benzene resulted in a statistically significant increase in the percentage of micronucleated cells in adult male bone marrow cells. In utero exposure to 400 mg/kg benzene throughout gestational days 7 to 15 also caused a statistically significant increase in the percentage of micronucleated cells in maternal bone marrow and post-natal bone marrow cells. Fetal liver cells also demonstrated a statistically significant increase in the percentage of micronucleated cells following 200 mg/kg and 400 mg/kg benzene. The third objective was to investigate the initiation of DNA recombination following in utero exposure to benzene using the pKZ1 mutagenesis mouse model as a surrogate marker for non-homologous end joining activity. Adult pKZ1 mouse tissue yielded no recombination events; however, post-natal bone marrow cells did contain detectable recombination frequencies. iii In utero benzene exposure did cause an increasing trend in recombination events, and upon analysis of only the samples containing detectable levels of recombination, in utero exposure to 400 mg/kg of benzene caused a statistically significant increase in recombination frequency within this group. These results demonstrate that benzene does not increase the formation of γ-H2A.X after acute and in utero exposure, however, the induction of micronuclei following acute and in utero benzene exposure confirmed that benzene is a genotoxic agent causing chromosomal breaks. In utero benzene exposure increased the frequency of DNA recombination in bone marrow from post-natal day 9 pups exhibiting detectable levels of recombination. Further investigations into different types of DNA damage and repair pathways are warranted to fully elucidate the role of genotoxic mechanisms in the etiology of benzene-induced childhood leukemias. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2008-08-22 11:07:49.162

Submitted by Marlene Aparecida de Souza Cardozo (mcardozo@pucsp.br) on 2016-12-20T10:49:37Z No. of bitstreams: 1 Ana Paula Bonilha Piccoli.pdf: 2544958 bytes, checksum: 55eb8d4d59715e56ad1f797400f11c86 (MD5) / Made available in DSpace on 2016-12-20T10:49:37Z (GMT). No. of bitstreams: 1 Ana Paula Bonilha Piccoli.pdf: 2544958 bytes, checksum: 55eb8d4d59715e56ad1f797400f11c86 (MD5) Previous issue date: 2016-11-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The childhood cancer corresponds to a diverse group of diseases whose common element uncontrolled proliferation of abnormal cells, and can occur anywhere in the body. Leukemias are the most common malignancies in childhood. The child is affected in its entirety by the reality of treatment and this is an important moment in its development. the benefits that promotes art therapy are known in the manifestation of psychological activity promoting access to internal content, increasing the well being of the individual and allowing application in diagnostic and therapeutic intervention approach. The aim of this study was that the effects of art therapy on the expression of emotional experiences of children in the treatment of leukemia. The effects studied were the feelings experienced by children with leukemia. We conducted a field survey and the results were treated qualitatively. Participants were four children diagnosed with acute lymphoblastic leukemia, between 5 and 8 years of age, of both sexes, attended an outpatient specialties of a provincial city of São Paulo. The instruments used were: Questionnaire socio-demographic and clinical history script. five sessions of art therapy directed with each child were held. The preparation of the sessions was to develop a technique of psychological research by art therapy, which can be associated with other techniques used in the clinical context and the imagistic content of the productions was analyzed in the light of Jungian psychology. One of the aspects discussed in this research is that expressive activities favored the expression of emotions and feelings of children about their disease process and also other aspects involving their emotional development. In this sense, there was contact between aspects of the conscious and the unconscious. The use of art through the proposed modalities: drawing, collage, painting and modeling made it possible to observe the establishment of emotional bond between her and her work. Some images were recurrent, as referring to polarities, such as life and death, death and rebirth, rain and sun, night and day. These images seem to appear as compensation ahead the imbalance arising from the process of becoming ill, as the regulatory function of the psyche. The making art and think about the production seem to have provided connection to channel the emotions of the participating children. It was noticed also that the sessions possibly helped children to develop their disease process. With regard to images and recurring colors, raise imagine that these are the manifestation of personal content and groups of children. Note that the open space where it ensured the manifestation of content through art was paramount to the imagistic content could be manifested. / O câncer na infância corresponde a um grupo de diversas doenças que tem como elemento comum a proliferação descontrolada de células anormais e podem ocorrer em qualquer parte do organismo. As leucemias são as neoplasias mais comuns na infância. A criança é afetada em sua totalidade pela realidade do tratamento e isso ocorre num momento importante de seu desenvolvimento. São conhecidos os benefícios que a arteterapia promove na manifestação da atividade psicológica como facilitadora de acesso aos conteúdos internos, ampliando o bem-estar do individuo e permitindo a aplicação numa abordagem de intervenção diagnóstica e terapêutica. O objetivo deste trabalho foi verificar quais os efeitos da arteterapia na expressão das vivências emocionais de crianças em tratamento de leucemia. Os efeitos estudados foram os sentimentos vivenciados pelas crianças com leucemia. Realizou-se uma pesquisa de campo e os resultados foram tratados qualitativamente. Participaram da pesquisa quatro crianças diagnosticadas com leucemia linfoide aguda, entre 5 e 8 anos de idade, de ambos os sexos, atendidas num ambulatório de especialidades de uma cidade interiorana de São Paulo. Os instrumentos utilizados foram: Questionário sócio demográfico e Roteiro de anamnese. Foram realizadas cinco sessões dirigidas de arteterapia com cada criança. A elaboração das sessões consistiu no desenvolvimento de uma técnica de investigação psicológica pela arteterapia, que pode ser associada a outras técnicas utilizadas no contexto clínico e o conteúdo imagético das produções foi analisado à luz da psicologia junguiana. Um dos aspectos discutidos nesta pesquisa é que as atividades expressivas favoreceram a expressão de emoções e sentimentos das crianças a respeito do seu processo de adoecimento e ainda de outros aspectos que envolveram seu desenvolvimento emocional. Nesse sentido, observou-se o contato entre aspectos do consciente e do inconsciente. O uso da arte através das modalidades propostas: desenho, colagem, modelagem e pintura fez com que fosse possível observar o estabelecimento de vínculo afetivo entre ela e a sua obra. Algumas imagens foram recorrentes, como as que remetem às polaridades, tais como vida e morte, morte e renascimento, chuva e sol, noite e dia. Essas imagens parecem surgir como compensação diante do desequilibrio advindo do processo de adoecer, como função reguladora da psique. O fazer arte e o pensar sobre a produção parecem ter proporcionado conexão com canais das emoções das crianças participantes. Percebeu-se, ainda, que as sessões possivelmente auxiliaram as crianças a elaborar seu processo de adoecimento. Com relação às imagens e cores recorrentes, suscitam imaginar que se tratam da manifestação de conteúdos pessoais e coletivos das crianças. Vale destacar que o espaço aberto onde se assegurou a manifestação de conteúdos mediante a arte foi primordial para que o conteúdo imagético pudesse ser manifestado

The purpose of the study was to summarize the literature about geographic information systems (GIS) and its applications in childhood cancer research. The main focus was to examine how GIS has been contributing to the research of childhood leukemia and its etiology. Since this is one of the diseases that can be connected to a public health issue, a thorough exploration of different areas outside the childhood cancer area had to be considered. Areas such as epidemiology and environmental health were two of the most relevant sources of literature. The etiology behind childhood leukemia has been studied for several decades, but the risk factors that cause this disease still remain largely unknown, and the results have been inconsistent. Since the 1990's, one of the methods to identify potential spatial clusters of childhood leukemia has been the use of GIS. This software has the ability to layer multiple risk factors in relation to the diagnosed children and thereafter visualize potential clusters on a map. The evaluation of the literature resulted in five topics which included most of the studies that has utilized GIS in their research of childhood leukemia. These five topics with its connected risk factors were: electromagnetic fields, ionizing radiation, air pollution, agricultural pesticides and hazardous waste sites. Even though few of the studies showed statistic significant clusters when connecting a potential risk factor with childhood leukemia, a majority of them didn't present any evidence about a causal relationship, which indicates a need of further research.

The cause for childhood acute lymphoblastic leukemia (ALL) remains unknown, but male gender is a risk factor, and among ethnicities, Hispanics have the highest risk. In this dissertation, we explored correlations among genetic polymorphisms, birth characteristics, and the risk of childhood ALL in a multi-ethnic sample in 161 cases and 231 controls recruited contemporaneously (2007-2012) in Houston, TX. We first examined three lymphoma risk markers, since lymphoma and ALL both stem from lymphoid cells. Of these, rs2395185 showed a risk association in non-Hispanic White males (OR=2.8, P=0.02; Pinteraction=0.03 for gender), but not in Hispanics. We verified previously known risk associations to validate the case-control sample. Mutations of HFE (C282Y, H63D) were genotyped to test whether iron-regulatory gene (IRG) variants known to elevate iron levels increase childhood ALL risk. Being positive for either polymorphism yielded only a modestly elevated OR in males, which increased to 2.96 (P=0.01) in the presence of a particular transferrin receptor (TFRC) genotype for rs3817672 (Pinteraction=0.04). SNP rs3817672 itself showed an ethnicity-specific association (Pinteraction=0.02 for ethnicity). We then examined additional IRG SNPs (rs422982, rs855791, rs733655), which showed risk associations in males (ORs=1.52 to 2.60). A polygenic model based on the number of polymorphic alleles in five IRG SNPs revealed a linear increase in risk (OR=2.00 per incremental change; P=0.002). Having three or more alleles compared with none was associated with increased risk in males (OR=4.12; P=0.004). Significant risk associations with childhood ALL was found with birth length (OR=1.18 per inch, P=0.04), high birth weight (>4,000g) (OR=1.93, P=0.01), and with gestational age (OR=1.10 per week, P=0.04). We observed a negative correlation between HFE SNP rs9366637 and gestational age (P=0.005), again, stronger in males (P=0.001) and interacting with TFRC (PPinteraction=0.05). Our results showed that (i) ALL risk markers do not show universal associations across ethnicities or between genders, (ii) IRG SNPs modify ALL risk presumably by their effects on iron levels, (iii) a negative correlation between an HFE SNP and gestational age exists, which implicates an iron-related mechanism. The results suggest that currently unregulated supplemental iron intake may have implications on childhood ALL development.

Le rôle de l'environnement dans l'étiologie des leucémies aigües de l’enfant (LA) fait aujourd'hui l'objet de recherches intenses. Dans ce contexte, le présent travail a pour objectif d’étudier la relation entre l’incidence de LA et la proximité des centrales nucléaires de production d’électricité (CNPE) et des lignes à haute tension (LHT). Avant cette analyse fine, un premier travail a consisté à étudier les variations départementales de l'incidence de LA.Les cas inclus dans ces études sont toutes les LA du Registre National des Hémopathies malignes de l’Enfant sur la période étudiée : 1990-2004 pour l’étude de l’incidence départementale et 2002-2007 pour les études de l’association avec les facteurs d’exposition environnementale. Dans l’approche cas-témoins principalement utilisée pour ces dernières, les 30 000 sujets témoins constitue un échantillon représentatif de la population pédiatrique française sur la période d’’intérêt. D’autre part, la géolocalisation des adresses des sujets et des sources d'exposition permet de définir des critères de proximité en relation avec la probabilité et/ou l'intensité d'exposition aux facteurs d'intérêt. • L’étude des LA par département n’a pas mis en évidence de tendance ni de structure spatiale dans l’incidence à ce niveau géographique : que ce soit globalement, par classe d’âge, par sexe ou par sous-type de leucémie. • Sur la période 2002-2007 contrairement aux périodes précédentes, un quasi-doublement de l’incidence des LA à moins de 5 km des CNPE a été mis en évidence, avec une approche cas-témoin comme avec l’étude d’incidence. Ce résultat n’était pas spécifique d’une CNPE ou d’un type de CNPE et non lié à la cartographie des émissions aériennes de radioactivité par les CNPE. • L’association trouvée entre l’incidence de LA et la proximité aux LHT de plus de 225 kV (<50 m) semble restreinte aux enfants de moins de 5 ans ou n’habitant en milieu urbain ; aucune association n’a été trouvée avec la proximité aux LHT de moins de 150 kV. / The role of the environment in the etiology of childhood acute leukemia (AL) is currently investigated. In this context, the aim of the present work is to study the association between the incidence of AL and the proximity no nuclear power plants (NPP) and to high voltage overhead power lines (HV OLs). At first, the geographical variations of AL have been studied at the Département level.The cases included in the studies are all cases of AL of the French National Registry of Childhood Haemopatopoietic Malignancies on the studied periods: 1990-2004 for the study of incidence on Départements and 2002-2007 for the studies of association between incidence of AL and environmental exposure factors. Concerning those latter studies, a case-control approach has been used. The control sample, representative of the French pediatric population, contains 30,000 subjects and has been drawn by the INSEE. The precise localization of addresses of subjects and of exposure sources in relation with the type of sources is essential to build indicators of exposure reflecting the probability and intensity of exposure. • The study of AL by Département has highlighted neither trend nor spatial structure in the incidence at this geographical level globally as well as by age, gender and subtype of leukemia.• On 2002-2007, on the contrary of on previous periods, the incidence of AL at less than 5 km from a NPP was nearly twice higher than expected, with the case-control study as well as with the incidence approach. This result was not specific to any age group, NPP, a type of NPP and was not associated with the geographic zoning of gaseous discharges of NPPs. • The study of the proximity to HV OLs highlighted an association between the incidence of AL and the close proximity (< 50 m) of lines of more than 225 kV, association which was restricted to children of less than 5 y.o. or living in non-urban areas; but not with the proximity to lines of less than 150 kV.

As leucemias correspondem a 30% dos tumores pediátricos, e constituem as neoplasias mais frequentes em indivíduos com menos de 15 anos. Apesar da elevada taxa de cura, frequentemente a ela está associada resistência à quimioterapia e efeitos colaterais tardios. Por isso, novas estratégias de tratamento, diagnóstico e prognóstico são necessárias. O fator neurotrófico derivado do cérebro (BDNF) e seus receptores de quinase relacionados à tropomiosina (tropomyosin related kinase, ou Trk) estão envolvidos com muitos processos na medula óssea (MO). Entretanto, o papel do BDNF em leucemias agudas (LA) pediátricas ainda não é bem conhecido. O objetivo desse estudo foi analisar os níveis de BDNF em amostras de MO ou sangue periférico (SP) de crianças com LA, e iniciar a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas sobre culturas primárias de leucemias linfóides agudas em diferentes momentos terapêuticos Foram coletadas amostras de MO ou SP de crianças e adolescentes com leucemia linfóide aguda (LLA), crianças e adolescentes com leucemia mielóide aguda (LMA), e indivíduos saudáveis (IS) da mesma faixa etária. Para análise dos níveis séricos de BDNF utilizou-se kit de imuno-ensaio enzimático tipo sanduíche. Quando comparados aos IS os níveis de BDNF de pacientes com LA, ao diagnóstico, foram significativamente menores. Resultados similares foram observados nos pacientes durante indução, consolidação, diagnóstico e tratamento de recidiva. Da mesma forma, os níveis de BDNF foram inferiores em pacientes que receberam transfusão de plaquetas e, ao diagnóstico naqueles pacientes que foram a óbito. Para a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas em cultura de células, amostras de pacientes ao momento do diagnóstico e no momento de indução do tratamento foram utilizadas. Os linfócitos foram extraídos e, após plaqueamento, as células foram tratadas com BDNF (Sigma, B3795), NGF (Sigma, SRP3015) e K252a (Sigma, 05288) por 72 horas. A viabilidade foi avaliada pelo método de exclusão por azul de Tripan. Devido às dificuldades no cultivo das células, esses dados ainda estão em análise. / Leukemias account for 30% of pediatric tumors and are the most frequent cancers in people under 15 years. Despite the high cure rate, often it is associated with resistance to chemotherapy and late side effects. Therefore, new strategies for treatment, diagnosis and prognosis are necessary. The brain-derived neurotrophic factor (BDNF) and their kinase receptor related tropomyosin (tropomyosin related kinase, and Trk) are involved in many processes in bone marrow (BM), however, the role of BDNF in acute leukemias (AL) pediatric it is not well known. The aim of this study was to analyze the BDNF levels in BM samples or peripheral blood (PB) of children with AL, and start the characterization of the effects of agonists and antagonists on neurotrophin primary cultures of acute lymphoblastic leukemias in different therapeutic moments. BM or PB samples were collected from children and adolescents with acute lymphoblastic leukemia (ALL), children and adolescents with acute myeloid leukemia (AML), and healthy individuals (HI) of the same age. For analysis of serum levels of BDNF was used sandwich enzyme immunoassay kit. When compared to HI, BDNF levels in patients with AL at diagnosis were significantly lower. Similar results were observed in patients during induction, consolidation, diagnosis and treatment of relapse. Similarly, BDNF levels were lower in patients receiving platelet transfusion and at diagnosis in patients that died. To characterize the effects of agonists and antagonists for neurotrophin in cell culture, samples of patients at diagnosis and at the time of induction treatment were used. Lymphocytes were extracted and, after plating, cells were treated with BDNF (Sigma B3795), NGF (Sigma, SRP3015) and K252a (Sigma, 05288) for 72 hours. Viability was assessed by exclusion of trypan blue method. Due to difficulties in cell culture, these data are still under analysis.

As leucemias correspondem a 30% dos tumores pediátricos, e constituem as neoplasias mais frequentes em indivíduos com menos de 15 anos. Apesar da elevada taxa de cura, frequentemente a ela está associada resistência à quimioterapia e efeitos colaterais tardios. Por isso, novas estratégias de tratamento, diagnóstico e prognóstico são necessárias. O fator neurotrófico derivado do cérebro (BDNF) e seus receptores de quinase relacionados à tropomiosina (tropomyosin related kinase, ou Trk) estão envolvidos com muitos processos na medula óssea (MO). Entretanto, o papel do BDNF em leucemias agudas (LA) pediátricas ainda não é bem conhecido. O objetivo desse estudo foi analisar os níveis de BDNF em amostras de MO ou sangue periférico (SP) de crianças com LA, e iniciar a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas sobre culturas primárias de leucemias linfóides agudas em diferentes momentos terapêuticos Foram coletadas amostras de MO ou SP de crianças e adolescentes com leucemia linfóide aguda (LLA), crianças e adolescentes com leucemia mielóide aguda (LMA), e indivíduos saudáveis (IS) da mesma faixa etária. Para análise dos níveis séricos de BDNF utilizou-se kit de imuno-ensaio enzimático tipo sanduíche. Quando comparados aos IS os níveis de BDNF de pacientes com LA, ao diagnóstico, foram significativamente menores. Resultados similares foram observados nos pacientes durante indução, consolidação, diagnóstico e tratamento de recidiva. Da mesma forma, os níveis de BDNF foram inferiores em pacientes que receberam transfusão de plaquetas e, ao diagnóstico naqueles pacientes que foram a óbito. Para a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas em cultura de células, amostras de pacientes ao momento do diagnóstico e no momento de indução do tratamento foram utilizadas. Os linfócitos foram extraídos e, após plaqueamento, as células foram tratadas com BDNF (Sigma, B3795), NGF (Sigma, SRP3015) e K252a (Sigma, 05288) por 72 horas. A viabilidade foi avaliada pelo método de exclusão por azul de Tripan. Devido às dificuldades no cultivo das células, esses dados ainda estão em análise. / Leukemias account for 30% of pediatric tumors and are the most frequent cancers in people under 15 years. Despite the high cure rate, often it is associated with resistance to chemotherapy and late side effects. Therefore, new strategies for treatment, diagnosis and prognosis are necessary. The brain-derived neurotrophic factor (BDNF) and their kinase receptor related tropomyosin (tropomyosin related kinase, and Trk) are involved in many processes in bone marrow (BM), however, the role of BDNF in acute leukemias (AL) pediatric it is not well known. The aim of this study was to analyze the BDNF levels in BM samples or peripheral blood (PB) of children with AL, and start the characterization of the effects of agonists and antagonists on neurotrophin primary cultures of acute lymphoblastic leukemias in different therapeutic moments. BM or PB samples were collected from children and adolescents with acute lymphoblastic leukemia (ALL), children and adolescents with acute myeloid leukemia (AML), and healthy individuals (HI) of the same age. For analysis of serum levels of BDNF was used sandwich enzyme immunoassay kit. When compared to HI, BDNF levels in patients with AL at diagnosis were significantly lower. Similar results were observed in patients during induction, consolidation, diagnosis and treatment of relapse. Similarly, BDNF levels were lower in patients receiving platelet transfusion and at diagnosis in patients that died. To characterize the effects of agonists and antagonists for neurotrophin in cell culture, samples of patients at diagnosis and at the time of induction treatment were used. Lymphocytes were extracted and, after plating, cells were treated with BDNF (Sigma B3795), NGF (Sigma, SRP3015) and K252a (Sigma, 05288) for 72 hours. Viability was assessed by exclusion of trypan blue method. Due to difficulties in cell culture, these data are still under analysis.

As leucemias correspondem a 30% dos tumores pediátricos, e constituem as neoplasias mais frequentes em indivíduos com menos de 15 anos. Apesar da elevada taxa de cura, frequentemente a ela está associada resistência à quimioterapia e efeitos colaterais tardios. Por isso, novas estratégias de tratamento, diagnóstico e prognóstico são necessárias. O fator neurotrófico derivado do cérebro (BDNF) e seus receptores de quinase relacionados à tropomiosina (tropomyosin related kinase, ou Trk) estão envolvidos com muitos processos na medula óssea (MO). Entretanto, o papel do BDNF em leucemias agudas (LA) pediátricas ainda não é bem conhecido. O objetivo desse estudo foi analisar os níveis de BDNF em amostras de MO ou sangue periférico (SP) de crianças com LA, e iniciar a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas sobre culturas primárias de leucemias linfóides agudas em diferentes momentos terapêuticos Foram coletadas amostras de MO ou SP de crianças e adolescentes com leucemia linfóide aguda (LLA), crianças e adolescentes com leucemia mielóide aguda (LMA), e indivíduos saudáveis (IS) da mesma faixa etária. Para análise dos níveis séricos de BDNF utilizou-se kit de imuno-ensaio enzimático tipo sanduíche. Quando comparados aos IS os níveis de BDNF de pacientes com LA, ao diagnóstico, foram significativamente menores. Resultados similares foram observados nos pacientes durante indução, consolidação, diagnóstico e tratamento de recidiva. Da mesma forma, os níveis de BDNF foram inferiores em pacientes que receberam transfusão de plaquetas e, ao diagnóstico naqueles pacientes que foram a óbito. Para a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas em cultura de células, amostras de pacientes ao momento do diagnóstico e no momento de indução do tratamento foram utilizadas. Os linfócitos foram extraídos e, após plaqueamento, as células foram tratadas com BDNF (Sigma, B3795), NGF (Sigma, SRP3015) e K252a (Sigma, 05288) por 72 horas. A viabilidade foi avaliada pelo método de exclusão por azul de Tripan. Devido às dificuldades no cultivo das células, esses dados ainda estão em análise. / Leukemias account for 30% of pediatric tumors and are the most frequent cancers in people under 15 years. Despite the high cure rate, often it is associated with resistance to chemotherapy and late side effects. Therefore, new strategies for treatment, diagnosis and prognosis are necessary. The brain-derived neurotrophic factor (BDNF) and their kinase receptor related tropomyosin (tropomyosin related kinase, and Trk) are involved in many processes in bone marrow (BM), however, the role of BDNF in acute leukemias (AL) pediatric it is not well known. The aim of this study was to analyze the BDNF levels in BM samples or peripheral blood (PB) of children with AL, and start the characterization of the effects of agonists and antagonists on neurotrophin primary cultures of acute lymphoblastic leukemias in different therapeutic moments. BM or PB samples were collected from children and adolescents with acute lymphoblastic leukemia (ALL), children and adolescents with acute myeloid leukemia (AML), and healthy individuals (HI) of the same age. For analysis of serum levels of BDNF was used sandwich enzyme immunoassay kit. When compared to HI, BDNF levels in patients with AL at diagnosis were significantly lower. Similar results were observed in patients during induction, consolidation, diagnosis and treatment of relapse. Similarly, BDNF levels were lower in patients receiving platelet transfusion and at diagnosis in patients that died. To characterize the effects of agonists and antagonists for neurotrophin in cell culture, samples of patients at diagnosis and at the time of induction treatment were used. Lymphocytes were extracted and, after plating, cells were treated with BDNF (Sigma B3795), NGF (Sigma, SRP3015) and K252a (Sigma, 05288) for 72 hours. Viability was assessed by exclusion of trypan blue method. Due to difficulties in cell culture, these data are still under analysis.

<p>The aim of the studies described in this thesis was to assess the association between certain perinatal factors and the risk of childhood lymphatic and myeloid leukemia and infant leukemia. </p><p>The five studies presented were all conducted in Sweden as population-based case-control studies. All cases were born and diagnosed between 1973-89 with leukemia up to the age of 16 years. A control was individually matched to each case. As Down’s syndrome entails a major risk for childhood leukemia, children with Down’s syndrome were excluded. The studies comprised a total of 652 cases, 47 of whom were diagnosed before the age of one year. Exposure data were extracted blindly from antenatal, obstetric, pediatric and other standardized medical records.</p><p>No association was found between prenatal exposure to ultrasound or diagnostic x-ray and childhood lymphatic or myeloid leukemia. Infant leukemia was associated with prenatal exposure to x-ray. A history of maternal lower genital tract infection significantly increased the risk of childhood leukemia, especially among children diagnosed at four years or older or in infancy. Factors such as young maternal age, and mothers working with children or in the health sector were associated with infant leukemia. Resuscitation with 100% oxygen with a face-mask and bag directly postpartum was associated with an increased risk of childhood lymphatic leukemia. The oxygen-related risk further increased if the manual ventilation lasted for three minutes or more. There was no association between lymphatic or infant leukemia and supplementary oxygen later in the neonatal period or other birth-related factors. Low Apgar scores at one and five minutes were associated with a non-significantly increased risk of lymphatic leukemia, and were significantly associated with infant leukemia.</p><p>Previously reported relations between childhood leukemia and exposures such as maternal diagnostic x-ray and birth related factors could not be confirmed by these studies. However, the present studies indicate that events during pregnancy or during the neonatal period are associated with increased risks of childhood and infant leukemia. These events can either be non-specific, such as exposure to maternal lower genital tract infection, or specific, such as the use of supplementary oxygen directly postpartum.</p>