The results of an experimental rearing of peled under different oxygen regimes are presented in this work. Four variants were tested in three repetitions (hypoxia 55-65 %, normoxia 85-95 %, permanent hyperoxia 145-155 % and alternate hyperoxia 145-155 % during the day and 85-95 % overnight). Also the oxygen consumption of fish with weight from 4.5 to 20 g at temperatures of 15, 19 and 23 °C was measured.

INTRODUÇÃO: A hipertensão arterial tem sido associada à hipersensibilidade quimiorreflexa arterial. A consequência dessa disfunção autonômica nessa população é a ativação simpática e vasoconstrição. De fato, a atividade nervosa simpática está aumentada e o fluxo sanguíneo muscular diminuído, em repouso e durante manobras fisiológicas como o exercício, em pacientes hipertensos. Contudo, o papel dos quimiorreceptores periféricos na resposta neurovascular durante o exercício não tem sido investigado nesses pacientes. OBJETIVO: Avaliar a influência dos quimiorreceptores periféricos no controle neurovascular da atividade nervosa simpática muscular (ANSM), condutância vascular no antebraço e pressão arterial em repouso, durante o exercício e a oclusão circulatória em pacientes com hipertensão arterial. MÉTODOS: Vinte e cinco sujeitos, na faixa etária entre 25 e 60 anos, sedentários, com índice de massa corporal menor que 30kg/m2 e não engajados em tratamento farmacológico participaram do estudo. Os participantes foram divididos em dois grupos, de acordo com o nível de pressão arterial clínica e classificados como hipertensos ou normotensos. Foram avaliados a ANSM (microneurografia), o fluxo sanguíneo muscular (pletismografia de oclusão venosa), a pressão arterial (oscilométrica), a frequência cardíaca (eletrocardiograma) e respiratória (cinta piezoelétrica) e a saturação de pulso de oxigênio (oxímetro). Todas as avaliações foram realizadas em repouso, durante o exercício de preensão de mão (30% da contração voluntária máxima) e durante a oclusão circulatória pós-exercício, em condições de normóxia (inalação de níveis ambientes com 21% de oxigênio) e hiperóxia (manobra que desativa os quimiorreceptores arteriais através da inalação da concentração de 100% de oxigênio). Em repouso, também foram avaliadas a variabilidade da frequência cardíaca e da pressão arterial e o ganho do controle barorreflexo da frequência cardíaca. Foi considerada diferença significativa quando P<0,05. RESULTADOS: No repouso, a desativação dos quimiorreceptores periféricos diminuiu a ANSM (38±3 vs. 34±3 disparos/minuto, P=0,02), aumentou o fluxo sanguíneo muscular (2,2±0,3 vs. 2,4±0,3 ml/min/100ml, P=0,02) e tendeu a aumentar a condutância vascular do antebraço (P=0,06) nos pacientes hipertensos. Além disso, a desativação dos quimiorreceptores periféricos aumentou o ganho do controle barorreflexo da frequência cardíaca (8±2 vs. 10±2 ms/mmHg, P=0,03) nesses pacientes tornando-os semelhantes ao grupo normotenso, quando comparados em condição de hiperóxia. Durante o exercício físico, a desativação dos quimiorreceptores periféricos diminuiu a resposta da ANSM nos pacientes hipertensos (A.S.C.= 131±8 vs. 116±9 disparos, P=0,005). No entanto, nenhuma modificação significativa foi observada na condutância vascular do antebraço e na pressão arterial. Interessantemente, durante a oclusão circulatória, manobra que isola os metaborreceptores musculares, a desativação dos quimiorreceptores periféricos aumentou a ANSM no primeiro e segundo minuto de oclusão (?= -2±2 vs. 3±1 disparos/min; ?= -4±2 vs. 3±1 disparos/min, P(grupo)= 0,02). CONCLUSÃO: Em pacientes hipertensos, a desativação dos quimiorreceptores periféricos: 1- Diminui a ANSM e aumenta o fluxo sanguíneo muscular e o ganho do controle barorreflexo da frequência cardíaca em repouso; 2-Diminui a resposta da ANSM durante o exercício e; 3- Normaliza o controle metaborreflexo da ANSM. Analisados em conjunto, esses resultados demonstram a participação do mecanismo quimiorreflexo periférico no controle neurovascular não só em repouso, mas também, durante a manobra fisiológica de exercício nos pacientes hipertensos / INTRODUCTION: Hypertension has been associated with augmented arterial chemoreflex sensitivity. The consequence of this autonomic dysfunction is an increased sympathetic outflow and vasoconstriction. Indeed, sympathetic nerve activity is increased and forearm blood flow is decreased at rest and during physiological maneuvers such as exercise, in hypertensive patients. However, the role of peripheral chemoreceptors in neurovascular response during exercise has not been investigated in these patients. OBJECTIVES: To evaluate the influence of peripheral chemoreceptors on neurovascular control of muscle sympathetic nerve activity (MSNA), forearm vascular conductance and blood pressure at rest, during exercise and postexercise circulatory arrest in patients with hypertension. METHODS: Twenty-five subjects, age between 25 and 60 years old, sedentary, with body mass index less than 30 kg/m2 and not engaged in pharmacological treatment participated in the study. The participants were divided into two groups according to their clinical blood pressure levels and were classified as hypertensive or normotensive. Were evaluated MSNA (microneurography), forearm blood flow (venous occlusion plethysmography), blood pressure (oscillometric), heart rate (electrocardiogram), respiratory rate (piezoelastic strap) and oxygen saturation (oxymeter). The evaluations were performed at rest, during a handgrip exercise (30% of the maximal voluntary contraction) and during postexercise circulatory arrest, in normóxia (breathing ambient air, containing 21% of oxygen) and hyperoxia (breathing air containing 100% oxygen, maneuver that deactivates the peripheral chemoreceptors). At rest, the variability of heart rate and blood pressure and the baroreflex control of heart rate were also evaluated. Significant differences were assumed to be when P<0.05. RESULTS: At rest, the deactivation of the peripheral chemoreceptors decreased the MSNA (38±3 vs. 34±3 bursts/min, P=0.02), increased forearm blood flow (2.2±0.3 vs. 2.4±0.3 ml/min/100ml, P=0.02) and tended to increase forearm vascular conductance (P=0.06) in hypertensive patients. Besides, the deactivation of the peripheral chemoreceptors increased the baroreflex control of heart rate (8±2 vs. 10±2 ms/mmHg, P=0.03) in these patients, toward to the normotensive group levels, when compared during hyperoxia condition. During exercise, the deactivation of peripheral chemoreceptors decreased the MSNA response in hypertensive patients (A.U.C.= 131±8 vs. 116±9 bursts, P=0.005). However, no significant changes were observed in forearm vascular conductance and blood pressure responses. Interestingly, during postexercise circulatory arrest, when the metaboreflex control is isolated, the deactivation of peripheral chemoreceptors increased the MSNA during the first and second minute of circulatory arrest (?= -2±2 vs. 3±1 bursts/min; ?= -4±2 vs. 3±1 bursts/min, P(group)=0.02). CONCLUSION: In hypertensive patients, the deactivation of the peripheral chemoreceptors: 1- Decreases the MSNA and increases the forearm blood flow and baroreflex control of heart rate at rest; 2- Decreases the MSNA response during exercise; 3- Normalizes the metaboreflex control of MSNA. Taken together, these results demonstrate the participation of the peripheral chemorreflex mechanism in the neurovascular control not only at rest, but also during the physiological maneuver of exercise in hypertensive patients

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-10-11T13:01:51Z No. of bitstreams: 1 carolinadelourdesjuliaovieira.pdf: 1329418 bytes, checksum: e45b4807f6fee58451c60f89e6788d07 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-10-16T13:55:41Z (GMT) No. of bitstreams: 1 carolinadelourdesjuliaovieira.pdf: 1329418 bytes, checksum: e45b4807f6fee58451c60f89e6788d07 (MD5) / Made available in DSpace on 2018-10-16T13:55:41Z (GMT). No. of bitstreams: 1 carolinadelourdesjuliaovieira.pdf: 1329418 bytes, checksum: e45b4807f6fee58451c60f89e6788d07 (MD5) Previous issue date: 2018-08-02 / A asma é considerada um problema de saúde pública mundial que envolve disparo de cadeia de eventos fisiopatológicos de difícil controle e tratamento. Estratégias terapêuticas vêm sendo estudadas para que a doença possa ser estabilizada e controlada. Porém, os eventos fisiopatológicos que envolvem a doença ainda não são totalmente esclarecidos. Tendo em vista esta premissa, estudos experimentais são necessários e estão em crescente desenvolvimento na comunidade científica com a finalidade de esclarecer o padrão de resposta inflamatória desencadeada no processo. Tanto em humanos quanto em camundongos BALB/c o processo fisiopatológico da asma desencadeia resposta celular clássica via células T helper 2 (Th2) com liberação de interleucinas (IL) inflamatórias. Além destes, infiltrado de macrófago, eosinófilos, mastócitos. Estudos evidenciam um desvio na via de desencadeamento desta resposta para via de células T helper 1 (Th1) mediada por IL-2 e interferon gama (IFN). A ativação da via celular Th17 também é citada, porém não totalmente elucidada quanto ao processo de imunorregulação. O objetivo do presente estudo foi verificar os mecanismos imunológicos pelos quais a hiperóxia leva a lesões em vias aéreas inferiores e parênquima pulmonar em modelo de asma experimental induzida por ovalbumina (OVA) em camundongos BALB/c. Para isto, realizamos a análise histopatológica do infiltrado inflamatório, do colágeno e do muco, por colorações histoquímicas, em amostras de tecido pulmonar, e quantificação dos níveis de interleucina 10 (IL-10), interleucina 22 (IL-22) e interleucina 17 (IL-17), pelo método ELISA, e nitrito (NO2), pelo método de Greiss, no lavado broncoalveolar. Os dados sugerem que a polarização para o fenótipo Th17 induzida pela hiperóxia é acompanhada por níveis mais altos no LBA, de IL-17, NO2, IL-10 e de IL-22. / Asthma is considered a worldwide public health problem that involves a chain of pathophysiological events of difficult control and treatment. Therapeutic strategies have been studied so that the disease can be stabilized and controlled. However, the pathophysiological events involving the disease are not yet fully understood. In view of this premise, experimental studies are necessary and are under increasing development in the scientific community in order to clarify the pattern of inflammatory response triggered in the process. Both in humans and in BALB/c mice the pathophysiological process of asthma triggers classical cell response via helper T (T 2) cells with release of inflammatory interleukins (IL). In addition, macrophage infiltrates, eosinophils, mast cells. Studies evidence a shift in the pathway of triggering this response to IL-2 and interferon gamma-mediated helper 1 (Th1) via pathway. Activation of the Th17 cell pathway is also cited, but not fully elucidated as to the immunoregulation process. The objective of our study was to verify the immunological mechanisms by which hyperoxia leads to lesions in the lower airways and pulmonary parenchyma in a model of experimental asthma induced by OVA in BALB / c mice. We performed the histopathological analysis of the inflammatory infiltrate, collagen and mucus, by histochemical staining, in lung tissue samples, and quantification of interleukin-10 (IL-10), interleukin-22 (IL-22) and interleukin-17 IL-17), by the ELISA method, and nitrite (NO2), by the method of Greiss, in bronchoalveolar lavage. The data suggest that the polarization for the Th17 phenotype induced by hyperoxia is accompanied by highest levels in the BAL of IL-17, NO2, IL-10 and IL-22.

Oxygen supplementation has been an important part of respiratory failure treatment in all fields of clinical medicine, especially on intensive care units (hereinafter referred to as ICU). Oxygen therapy is a life-saving measure but indiscriminate administration of oxygen can cause lung and nerve damage and consequently increase morbidity and mortality (1). In clinical practice we often encounter mechanically ventilated patients with high partial pressures of oxygen in arterial blood (5) which should direct our attention to possible consequences and have reliable data how is oxygen treatment managed. This thesis focuses on the exposure to toxic concentrations of oxygen on the resuscitation ward. The aim of this thesis is to determine whether patients are exposed to high concentrations of oxygen. Two other aims of this study are to find out how long are patients in a state of hyperoxemia and whether medical staff reacts to measured partial pressures of oxygen (hereinafter referred to as paO2) values in these patients by reducing oxygen fraction (hereinafter referred to as FiO2) on the ventilator. The research part of this thesis is a quantitative observational retrospective research. The inclusion criteria were hospital admission from 1st July to 1st October 2019, at least two paO2 values greater...

Bronchopulmonary dysplasia (BPD) is a chronic lung disease and one of the most severe complications that develop in premature infants following mechanical ventilation, exposure to supplemental oxygen, and inflammation. The hallmarks of the lung pathology are arrested lung development, including fewer and larger alveoli with less septation, thickening of alveolar septa, and impaired development of the capillary network. BPD is associated with increased mortality, respiratory morbidity, neurodevelopmental impairment, and increased healthcare costs. Significant advancements in neonatology in the last several decades, including antenatal steroids and exogenous surfactant replacement therapy, more gentle ventilation methods, and judicious oxygen use, have allowed for the survival of more preterm infants. However, the incidence of BPD still remains high and currently, there is no cure for the disease. Novel effective interventions at this stage of life are of exceptional value. Considering their great potential in promoting tissue regeneration and modulating inflammation, mesenchymal stromal cells (MSCs) represent a promising avenue for treating several disorders, including BPD. Umbilical cord-derived MSCs (UC-MSCs) offer biological advantages over other MSC sources (easily available, high proliferative capacity, and better repair efficacy). Pioneering work in our lab showed that MSCs prevent injury to the developing lung in a rat model mimicking BPD. However, there are still considerable challenges that must be overcome before MSCs can be effectively implemented in clinical trials. As such, UC-MSC heterogeneity is poorly understood, with concerns regarding variations from donors and batches. Thus, to improve the reproducibility of basic research and clinical applications, and to identify the optimal therapeutic cell product, better molecular characterization of UC-MSCs and the development of standardized BPD models will be essential in the clinical translation of MSC therapy for BPD. Moreover, considering that BPD is a disease of prematurity, the therapeutic potential of UC-MSCs isolated from preterm birth is of major interest. In the study presented here, using single-cell RNA sequencing (scRNA-seq), we characterized MSCs isolated from the UC of term and preterm pregnancies at delivery (term and preterm donors), as well as non-progenitor control cell line, human neonatal dermal fibroblasts (HNDFs). Moreover, we associated UC-MSC transcriptomic profiles with their therapeutic potential in hyperoxia-induced lung injury in neonatal rats. Finally, we developed and characterized a novel two-hit (2HIT) BPD model in neonatal mice, assessed UC-MSCs' optimal route of injection, timing, and dose, and evaluated their therapeutic effects in that model. We showed that UC-MSCs isolated from the majority of term and preterm donors, including preterm donors with pregnancy-related complications, have limited heterogeneity and possessed a transcriptome enriched in genes related to cell cycle and cell proliferation activity (termed "progenitor-like" cells). In contrast, UC-MSCs isolated from one term and two preterm donors with preeclampsia displayed a unique transcriptome comprised of many genes related to fibroblast activity, including extracellular matrix (ECM) organization (termed "fibroblast-like" cells). In addition, treatment with progenitor-like UC-MSCs, but not with fibroblast-like cells nor HNDFs, significantly improved lung structure, function, and pulmonary hypertension (PH) in hyperoxia-induced lung injury in neonatal rats. We identified marker genes for the therapeutic UC-MSCs (progenitor-like cells) and non-therapeutic cells (fibroblast-like cells and HNDFs). Among them, the high expression of major histocompatibility complex class I (MHCI) is associated with a reduced therapeutic effect. Furthermore, we developed a novel 2HIT BPD mice model with in-depth characterization of the innate immune response and lung injury. 2HIT injury caused a transient type 1 proinflammatory cytokine response and a significant decrease in type 2 anti-inflammatory cytokine lung expression and number of anti-inflammatory M2 type alveolar macrophages. Moreover, 2HIT mice showed impaired lung compliance and growth. Repeated intravenous (i.v.) injections of UC-MSCs at a dose of 20×10⁶ cells/kg body weight (BW) on postnatal day (PD) one and two improved survival, BW, lung compliance, and growth of 2HIT animals. In conclusion, scRNA-seq experimentation provided evidence that UC-MSCs isolated from different donors harbor different transcriptomes with progenitor-like or fibroblast-like characteristics. Only progenitor-like cells provided a therapeutic effect in hyperoxia-induced lung injury in neonatal rats. The development of a novel murine 2HIT BPD model allowed us to characterize the innate immune response and lung pathology and confirm the optimal dose of UCMSCs to provide therapeutic potential in that model. These results will enable better therapeutic selection of UC-MSCs and help improve treatment regimen prior to ultimate clinical translation.

Réalisé en cotutelle avec l'Université de Lorraine (France) / Ce projet traite de la programmation développementale de l’hypertension artérielle (HTA) à travers des influences néonatales précoces pouvant moduler le développement vasculaire. Les bébés prématurés présentent des défenses antioxydantes diminuées comparés aux nouveau-nés à terme et sont exposés à la naissance à des concentrations élevées en oxygène (O2) engendrant la production d’espèces réactives de l’O2 (ERO). Les conséquences vasculaires à long terme de dommages liés aux ERO en période néonatale et les mécanismes impliqués sont très partiellement compris. Les précédents résultats du laboratoire ont montré qu’un stress hyperoxique néonatal conduit chez le rat adulte à de l’HTA, une dysfonction endothéliale et une rigidité artérielle, éléments de vieillissement vasculaire. Nous émettons l'hypothèse qu'un stress hyperoxique néonatale conduit à long terme à l'altération de la structure vasculaire et à un vieillissement vasculaire précoce. Nous avons démontré une diminution de la prolifération cellulaire, une capacité angiogénique altérée, des dommages à l’ADN et une augmentation de l’expression de protéines de sénescences (des indices de sénescence cellulaire) au-delà de la période néonatale suite à une exposition brève à l’O2 au niveau vasculaire dans un modèle animal (ratons Sprague-Dawley exposés à 80 % d’O2 du 3ème au 10ème jour de vie comparés à des ratons restés à l’air ambiant) et cellulaire (cellules musculaires lisses d'aortes thoraciques d'embryon de rat exposées à 40% O2 pendant 24h ou 48h, puis remises en normoxie pendant 96h). De plus, des altérations des composants de la structure vasculaire indiquant un remodelage vasculaire aortique ont été mises en évidence. Ces changements précèdent tous l’HTA et la dysfonction vasculaire observées dans le modèle animal à l’âge adulte et pourraient y contribuer. L’étude de jeunes adultes nés < 29 semaines comparés à des jeunes adultes nés à terme indique une augmentation de marqueurs de rigidité artérielle (indices d’un vieillissement vasculaire précoce) chez la population prématurée. L’ensemble des résultats démontre un vieillissement vasculaire précoce après une exposition néonatale transitoire à un stress hyperoxique permettant une meilleure compréhension des mécanismes physiopathologiques impliqués dans la survenue des troubles vasculaires retrouvés chez l’adulte et contribue à la mise en place de moyens de prévention chez des patients prématurés. / The scope of this thesis is developmental programming of arterial high blood pressure (HBP) hypertension through early neonatal stimuli that may alter vascular development. Premature newborns have decreased antioxidant defenses compared to term babies and are exposed upon birth to high oxygen (O2) concentration, causing reactive oxygen species (ROS) production. Long term vascular consequences of ROS related damage during the neonatal period and the mechanisms involved remain unknown. Recent data from the laboratory show that neonatal hyperoxic stress leads in adult rat to HBP, endothelial dysfunction and arterial rigidity, characteristic features of vascular aging. We hypothesize that a neonatal hyperoxic stress leads to long term vascular structure alteration explained by an early aging of the vascular system. We showed a decreased proliferation rate, an altered angiogenic capacity, as well as long term DNA damage and increased expression of senescence proteins at a vascular level following O2 exposure in the animal (male Sprague-Dawley pups kept at 80% O2 from postnatal days 3 to 10 vs. rats remained in room air) and cellular models (embryonic vascular smooth muscle cells from rat thoracic aorta exposed to 40% O2 for 24h or 48h followed by 96h recovery in control conditions). In addition, alterations of vascular structure components indicating vascular remodeling was shown before the onset of the HBP at adult age. Those changes precede the HBP and vascular dysfunction observed in our animal model at adult age and could contribute to them. Study of young adults born before 29 weeks vs. young adults born at term showed that young adults born preterm present indices of arterial stiffness vs. term controls. Results of the present thesis demonstrate a major role of premature vascular aging in the surge of vascular diseases in adulthood and contribute to a better understanding of the patho-physiological mechanisms involved and could put into practice new prevention strategies among preterm patients.

L'étude des mécanismes physiologiques au cours d'une plongée subaquatique estessentielle à la compréhension des accidents qui lui sont associées. Le plongeur subit denombreuses contraintes issues du milieu dans lequel il évolue. Parmi ces contraintes, qui leplus souvent se combinent, nous pouvons citer l'immersion, l'exposition au froid,l'hyperbarie, les variations des conditions d'oxygénation (hypoxie, hyperoxie) et l'exercicephysique. L'objectif de notre travail a été d'apprécier les modifications de la fonction cardiovasculaireet de son contrôle neuro-végétatif induites par ces contraintes rencontrées enplongée chez des sujets sains, novices en plongée, et également chez des chasseurs sousmarins. L'étude de la circulation artérielle et de la fonction endothéliale était basée surl'échographie (bi-dimensionnelle et Doppler). Des mesures de tonométrie d'applanation etautres mesures ultrasonores ont complété nos données hémodynamiques. L'étude du systèmeneurovégétatif était basée sur l'analyse de la variabilité de l'intervalle RR (contrôle cardiaque)et de la variabilité de la pression artérielle (contrôle vasculaire). Après un exercice aigu de pédalage de 45 minutes à haute intensité, l'augmentationpost-exercice du flux sanguin et de la vasodilatation endothéliale a été réduite aux musclesparticipant activement à l'exercice comparé aux muscles non actifs. Pour expliquer cesdifférences, la contribution de l'inflammation locale et du stress oxydatif élevé présents dansles muscles actifs de l'exercice pourrait avoir un rôle. / During a dive, subjects undergo environmental stressors such as immersion, coldexposure, hypoxia, hyperoxia and physical exercise. All these stressors may be responsible forchanges in cardiovascular system and consequently modified autonomic nervous control. Theaim of this work was to assess physiological changes induced by diving to better understandinjuries reported during this activity. Investigations were performed in healthy men and inspearfishermen. Hemodynamic changes and endothelial function were assessed by 2-Dimensional and Doppler echocardiography. Arterial wall compliance was estimated by pulsewave analysis. Autonomic nervous activity was assessed by power spectral density of heartrate variability (cardiac control) and blood pressure variability (vasomotor control). After an acute cycling exercise of 45 minutes in high intensity, the increase postexerciseof the blood flow and the endothéliale vasodilatation was reduced to musclesparticipating actively in the exercise compared with no active muscles. To explain thesedifferences, the contribution of the local inflammation and the important oxydative stress inthe active muscles of the exercise could have a role. Thermoneutral head-out water immersion induce hemodynamic and arterial changes. At rest, we observed a brachial arterial vasodilatation. This might be attributed to endothelialrequest inferred by increase of the peripheral arterial debit flow. Endothelial reactivity did notseem to be modified. With cycling exercise in low intensity,hemodynamic differencesobserved disappear. At rest, normobaric hyperoxia didn't affect blood pressure but induced an increase insystemic vascular resistances.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O oxigênio é importante não só por sua participação no metabolismo energético, mas também por sua conversão em derivados parcialmente reduzidos, as espécies reativas de oxigênio (ERO). ERO participam de funções importantes em diversas vias do metabolismo, entretanto, em concentrações desequilibradamente elevadas deflagram a peroxidação lipídica, processo deletério que forma aldeídos tóxicos, como o 4-hidroxi-2-nonenal (4-HNE). A manutenção de concentrações não deletérias das ERO é realizada por moléculas componentes do sistema antioxidante. Peixes podem ser expostos a grandes variações das concentrações de oxigênio, o que provoca ciclos oxidantes. A maioria dos estudos usa fígado e rim para avaliar estresse oxidante por meio de ensaios das atividades antioxidantes, o que requer o sacrifício dos animais. Contudo, o sangue sofre efeitos das ERO e avaliações no sangue podem permitir o estudo de antioxidantes no mesmo animal, sem a necessidade de sacrifício. Em consequência, foram nossos objetivos estabelecer uma técnica de cateterismo branquial em peixes, a padronização dos ensaios e a avaliação em sangue de componentes do sistema antioxidante de duas espécies de teleósteos em diferentes tensões de oxigênio. Pacus e tilápias foram avaliados em 6,0 mg de O2.L-1 e em hipoxia a 0,5 mg de O2.L-1 por 42 horas . Para os ensaios de hiperoxia os animais foram avaliados em 6,0 mg de O2.L-1, depois de 6 horas em 9,5 mg de O2.L-1 e depois de 30 horas de recuperação a 6,0 mg de O2.L-1. A utilização de materiais para o cateterismo de humanos permitiu a implantação de um acesso branquial. Infelizmente, houve formação de trombo após 24 horas. Mesmo assim, a observação de fluxo sanguíneo no interior da cânula e a sobrevida dos animais testados, confirmam a viabilidade da técnica. Verificamos em sangue uma maior atividade da enzima glutationa S-transferase (GST) sobre o 4-HNE em relação ao 1-cloro-2-dinitrobenzeno (CDNB). Isto reflete a importância de avaliações de atividade de enzimas, como a GST, sobre substratos endógenos. As respostas enzimáticas de tilápias mostraram-se mais sensíveis que as dos pacus quando comparadas em diferentes tensões de oxigênio. / Oxygen is important not only for their role in energy metabolism, but also for its conversion into partially reduced derivatives, the reactive oxygen species (ROS). ROS participate in important roles in several metabolic pathways, however, at concentrations lopsidedly high they trigger lipid peroxidation process to form deleterious toxic aldehydes such as 4-hydroxy-2-nonenal (4-HNE). Maintenance of non deleterious concentrations of ROS molecules is performed by components of the antioxidant system. Fish may be exposed to large variations in the concentrations of oxygen, which causes oxidative cycles. Most studies use liver and kidney to assess oxidative stress through antioxidant activities assay, which requires the sacrifice of animals. However, the blood undergoes effects of ROS and evaluations in blood may allow the study of antioxidants in the same animal, without the need of sacrifice. Consequently, our objectives were to establish a catheterization technique in fish gill, standardization of testing and evaluation of components of blood antioxidant system of two species of teleost in various oxygen tensions. Pacus and tilapias were evaluated at 6.0 mg O2.L-1 hypoxia and 0.5 mg O2.L-1 for 42 hours. For assays of hyperoxia animals were evaluated at 6.0 mg O2.L-1, after 6 hours at 9.5 mg O2.L-1 and after 30 hours recovery at 6.0 mg O2.L-1. The use of materials of human catheterization allowed the implantation of a gill access. Unfortunately, there was thrombus formation after 24 hours. Nevertheless, the observation of blood flow within the cannula and survival of the animals tested, confirm the viability of the technique. We found blood in a higher activity of glutathione S-transferase (GST) on the 4-HNE compared to 1-chloro-2-dinitrobenzene (CDNB). This reflects the importance of assessing the activity of enzymes, such as GST with endogenous substrates. The enzymatic responses of tilapia were more sensitive than those of pacus when compared to different oxygen tensions.

INTRODUÇÃO: Baixos níveis séricos de fator de crescimento insulin-like I (IGF- 1) ao nascimento têm sido considerados um fator de risco para o desenvolvimento da retinopatia da prematuridade em recém-nascidos prematuros de extremo baixo peso. Isto se deve ao seu papel como fator permissivo para o fator de crescimento endotelial vascular (VEGF) exercer sua função no desenvolvimento normal e patológico dos vasos da retina. OBJETIVO: Testar a hipótese de que a administração do JB-1 (um análogo do IGF-1 que inibe de forma potente a auto-fosforilação do receptor do IGF-1 pelo IGF-1) durante a hiperóxia previne a retinopatia induzida por oxigênio em nosso modelo experimental em ratos. MATERIAL E METODOS: Ratos recém-nascidos foram expostos a 50% de oxigênio com três episódios consecutivos de hipóxia (12% de oxigênio) do nascimento ao 14º dia de vida. Os ratos foram tratados com injeções subcutâneas de 1) JB-1 (1g/d) nos três primeiros dias de vida (JB-1 x3); 2) JB- 1(1g/d) por dias alternados do 1º ao 13º dias de vida (JB-1x7) 3) ou volume equivalente de solução salina. Grupos controles foram criados em ar ambiente nas mesmas condições, exceto pelo ciclo de hiperóxia/ hipóxia. Os grupos foram analisados após a exposição ao oxigênio no 14º dia de vida ou deixados em ar ambiente por mais sete dias até o sacrifício, no 21º dia de vida. Determinou-se as dosagens sistêmicas e oculares de fator de crescimento endotelial vascular (VEGF), receptor tipo1 solúvel do fator de crescimento endotelial vascular (sVEGFR-1) e fator de crescimento insulin-like I (IGF-1), associados a análise da vascularização retiniana e do perfil dos genes relacionados à angiogênese retiniana. RESULTADOS: O tratamento com JB-1x3 resultou em supressão efetiva da retinopatia induzida por oxigênio, sem efeitos adversos no crescimento somático e foi associado a um aumento do sVEGFR-1 quando comparado com o JB-1x7. Ao contrário, o tratamento com JB-1x7 durante a exposição ao oxigênio levou à diminuição do peso corpóreo e níveis mais altos de IGF-1 e VEGF relacionados à presença de tortuosidades vasculares e neovascularização retiniana, quando comparado com as retinas que receberam apenas solução salina. CONCLUSÃO: O tratamento curto e sistêmico com JB-1 durante a hiperóxia resultou em prevenção da retinopatia induzida por oxigênio sem restrição do crescimento somático. Novos estudos devem ser realizados para determinar se o JB-1 pode ser usado em recém-nascidos de extremo baixo peso na prevenção da retinopatia da prematuridade / INTRODUCTION: Low serum insulin growth factor (IGF-1) levels at birth is a risk factor for the development of retinopathy of prematurity in extremely low birth weight infants. This may be due to its role as a permissive factor for vascular endothelial growth factor (VEGF) function in normal and pathologic vascular development. OBJECTIVE: To test the hypothesis that JB-1 (an IGF-1 analog that potently inhibits the autophosphorylation of the IGF-1 receptor by IGF-1) administration during hyperoxia prevents oxygen induced retinopathy in our rat model. MATERIAL AND METHODS: Neonatal rats were exposed to 50% oxygen with brief, clustered, hypoxic (12% oxygen) episodes from birth to day 14. The pups were treated with subcutaneus injections of 1) JB-1 (1g/d) on the first, second, and third day (JB-1x3) 2) JB1 (1g/d) on alternate days from first to day 13 (JB- 1x7); or equivalent volume of saline. Control littermates were raised in room air with all conditions identical except for inspired oxygen. Groups were analyzed after hyperoxia/hypoxia cycling on day 14 or allowed to recover in room air until the 21st day. Systemic and ocular VEGF, soluble VEGFR-1, and IGF-1; retinal vasculature and gene profile of retinal angiogenesis were assessed. RESULTS: JB-1x3 treatment resulted in successful suppression of oxygeninduced retinopathy with no adverse effect on anthropometric growth, which was associated with increased sVEGFR-1 compared to JB-1x7. In contrast, intermittent and long exposure to JB-1 (JB-1x7) during the hyperoxia/hypoxia cycling period resulted in decreased body weight and higher ocular IGF-1 and VEGF levels as well as vascular tortuosity and retinal neovascularization compared with saline treated retinas. CONCLUSION: Systemic treatment with JB-1 during hyperoxia results in successful prevention of oxygen-induced retinopathy with little adverse effects on anthropometric growth. Further confirmatory studies are needed to determine whether systemic JB-1 should be used in extremely low birth weight infants to prevent retinopathy of prematurity