Anoxia is an environmental stress that few air-breathing vertebrates can tolerate for more than a few minutes before extensive neurodegeneration occurs. Some facultative anaerobes, including the freshwater western painted turtle Chrysemys picta bellii, are able to coordinately reduce ATP demand to match reduced ATP availability during anoxia, and thus tolerate prolonged insults without apparent detriment. To reduce metabolic rate, turtle neurons undergo channel arrest and spike arrest to decrease membrane ion permeability and neuronal electrical excitability, respectively. However, although these adaptations have been documented in turtle brain, the mechanisms underlying channel and spike arrest are poorly understood. The aim of my research was to elucidate the cellular mechanisms that underlie channel and spike arrest and the neuroprotection they confer on the anoxic turtle brain. Using electrophysiological and fluorescent imaging techniques, I demonstrate for the first time that: 1) the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) undergoes anoxia-mediated channel arrest; 2) delta opioid receptors (DORs), and 3) mild mitochondrial uncoupling via mitochondrial ATP-sensitive K+ channels result in an increase in cytosolic calcium concentration and subsequent channel arrest of the N-methyl-D-aspartate receptor, preventing excitotoxic calcium entry, and 4) reducing nitric oxide (NO) production; 5) the cellular concentration of reactive oxygen species (ROS) decreases with anoxia and ROS bursts do not occur during reoxygenation; and 6) spike arrest occurs in the anoxic turtle cortex, and that this is regulated by increased neuronal conductance to chloride and potassium ions due to activation of γ–amino-butyric acid receptors (GABAA and GABAB respectively), which create an inhibitory electrical shunt to dampen neuronal excitation during anoxia. These mechanisms are individually critical since blockade of DORs or GABA receptors induce excitotoxic cell death in anoxic turtle neurons. Together, spike and channel arrest significantly reduce neuronal excitability and individually provide key contributions to the turtle’s long-term neuronal survival during anoxia. Since the turtle is the most anoxia-tolerant air-breathing vertebrate identified, these results suggest that multiple mechanisms of metabolic suppression acting in concert are essential to maximizing anoxia-tolerance.

This thesis examined the impact of oxygen (O2) availability on prefrontal cortex and muscle tissue oxygenation during repeated-sprint exercise (RSE) in men and women. Men and women matched for initial-sprint mechanical work performed during ten, 10-s sprints (30s of rest) in normoxia (21% FIO2) and acute hypoxia (13% FIO2). Mechanical work and arterial O2-saturation (SPO2) were obtained for every sprint. Oxy- and deoxygenated haemoglobin concentrations (O2Hb, HHb) were obtained via near-infrared spectroscopy. Hypoxia elicited lower SPO2 and work (14.8% & 7.4%, P < 0.05), larger (45.1%, P < 0.05) and earlier reductions in cortical oxygenation, and no differences between sexes. Cortical de-oxygenation and work decrement were strongly correlated (R2=0.85, P < 0.05). Muscle de-oxygenation was greater in men than women (67.3%, P < 0.05). These results show that O2 availability influences cortical oxygenation and performance equally in men and women, and suggest a more efficient muscle O2 uptake in women. / ix, 108 leaves : ill. ; 29 cm

Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Embargoed. Vita. Bibliography: 97-112.

Le stress oxydatif définit un phénomène cellulaire particulier caractérisé par un niveau élevé de molécules hautement réactives, essentiellement lié à l’utilisation de l’oxygène par les systèmes biologiques via la respiration. La dérégulation de l’état oxydatif de la cellule est à l’origine soit de processus d’adaptations efficaces (adaptation à l’altitude) soit de pathologies (AVC, infarctus). Ce travail de thèse s’est porté sur l’étude de deux nouvelles cibles pouvant induire une résistance/tolérance à la variation du stress oxydatif : la première est la protéine canal CFTR («Cystic Fibrosis Transmembrane conductance Regulator») et la seconde la voie d’activation d’eIF5A («eukaryotic Initiation translation Factor 5A»). Nous avons pu mettre en évidence que la protéine CFTR grâce à sa perméabilité au glutathion (l’antioxydant majoritaire cellulaire) est un modulateur de l’état oxydatif de la cellule, que ce soit lors de l’exposition à des agents cytotoxiques (cisplatine) ou lors de l’adaptation à des conditions hypoxiques chroniques. La deuxième cible identifiée est le facteur eIF5A qui est la seule protéine activée par la fixation d’un résidu hypusine. L’inhibition de cette modification post-traductionnelle protège les cellules d’une production d’espèces réactives induite par l’anoxie. Cette résistance à l’anoxie est accompagnée d’un profond remodelage métabolique et mitochondrial. Sur des modèles animaux d’ischémie (rein et cerveau), l’inhibition de l’activation d’eIF5A conduit à une protection des organes face à un manque d’oxygène. Ces études fondamentales ont des applications cliniques potentielles dans des pathologies humaines (infarctus, AVC, transplantation). / Oxidative stress represents a particular cellular condition, characterized by an intracellular increase in thereactive species level. These species are highly reactive towards biomolecules and result of oxygenconsumption by biological systems essentially through respiration. Deregulation of the cellular oxidativestate can initiate adaptive processes (as elevation adaptation) or several human pathologies (stroke,infarct). This thesis work has been devoted to the study of two news potential targets allowing atolerance/resistance towards disequilibrium of oxidative stress; the first one is CFTR, a channel protein(«Cystic Fibrosis Transmembrane conductance Regulator»), and the second one is the activation pathwayof the translation factor eIF5A («eukaryotic Initiation translation Factor 5A»). Based on the peculiaractivity of CFTR, consisting in the transport of glutathione, the major antioxidant of the cell, weevidenced the role of CFTR in the management of cellular oxidative state during cytotoxic drugexposure (cisplatin) or during adaptation to chronical hypoxia. The second target, eIF5A is the only oneprotein described as post-translationally modified by fixation of a hypusine residue. We demonstratedthat inhibition of eiF5A activation protect cells from reactive oxygen species generated during anoxia. Atcellular level, this protection is accompanied with deep metabolic and mitochondrial changes. Usinganimal models, we showed that inhibition of this eiF5A activation allows a tolerance against ischemicaccident in different organs (kidney and brain). These fundamentals results can have extensiveapplication in human clinical use (infarct, stroke, graft).

Made available in DSpace on 2014-12-17T15:32:30Z (GMT). No. of bitstreams: 1 MarceloGV_TESE.pdf: 4128129 bytes, checksum: ebce1d2816c557119bfc6ec3a006f620 (MD5) Previous issue date: 2011-11-18 / The tumor hypoxia modulates a series of genetic changes related to adaptive development, invasion and metastasis of various human cancers, among which squamous cell carcinoma of the tongue (SCCT). The objective of this study was to analyze clinical, morphological and immunohistochemical expression by HIF-1&#945;, GLUT-1 and CA-IX in 57 cases of CEL and correlated this expression to clinical parameters and morphological. After a descriptive analysis of data on gender, age, race, and habits of patients, it was found that the results were consistent with the literature. The clinical and morphological parameters analyzed and the expression of these markers of hypoxia were subjected to statistical analysis (Qui2 test), verifying that they can be used as indicators of the biological behavior of CEL. Among the results of this study, we observed that the intensity of expression for HIF-1&#945;, in most cases located in the cytoplasm and nucleus, statistically correlated with clinical staging (p = 0.011) and histological grading (p = 0.002). As for the relationship between the distribution of labeling for HIF-1&#945; and metastasis, the chi-square (Qui2) showed that there was statistically significant differences between the groups (p = 0.040). 75.8% of the sample who had metastases, there was the predominance of diffuse marking. The immunoexpression cytoplasmic/membrane GLUT-1 showed a statistically significant correlation with the clinical stage (p = 0.002) and histological grading (p = 0.000). Concerning the location of markings for GLUT-1 tumor on the island, there was a predominance of peripheral marking specimens in most low-grade (78.6%). In the sample of high-grade, prevailed the location center/periphery (55.8%). According to the chi-square (Qui2), the location on the island of the tumor (p = 0.025) showed statistically significant difference in histological grading. The immunoreactivity of CA-IX, in most cases located in the membrane and cytoplasm, exhibited a statistically significant correlation with histological grading (p = 0.005). Based on these results, we can conclude a broad participation of these markers of hypoxia in oral carcinogenesis and its possible use as markers of biological behavior and tumor progression in CEL / A hip?xia tumoral modula uma s?rie de mudan?as gen?ticas adaptativas relacionadas ao desenvolvimento, invas?o e met?stase de diversos c?nceres humanos, dentre os quais o carcinoma epiderm?ide de l?ngua (CEL). O objetivo do presente trabalho foi realizar uma an?lise cl?nica, morfol?gica e imuno-histoqu?mica atrav?s da express?o do HIF-1&#945;, GLUT-1 e da CA-IX em 57 casos de CEL, correlacionando essa express?o ? par?metros cl?nicos e morfol?gicos. Ap?s uma an?lise descritiva dos dados referentes ao sexo, faixa et?ria, ra?a e h?bitos dos pacientes, constatou-se que os resultados encontrados foram condizentes com a literatura. Os par?metros cl?nicos e morfol?gicos analisados e a express?o desses marcadores de hip?xia foram submetidos ? an?lise estat?stica (teste do Qui2), verificando-se que os mesmos podem ser utilizados como indicadores do comportamento biol?gico do CEL. Dentre os resultados da presente pesquisa, observou-se que a intensidade de express?o para o HIF-1&#945;, localizada na maioria dos casos no citoplasma e n?cleo, correlacionou-se estatisticamente com o estadiamento cl?nico (p = 0,011) e grada??o histol?gica (p = 0,002). Quanto ? rela??o entre a distribui??o de marca??o para o HIF-1&#945; e met?stase, o teste qui-quadrado (Qui2) demonstrou haver diferen?as estatisticamente significativas entre os grupos analisados (p = 0,040). Dos 75,8% da amostra que tinham met?stase, constatou-se a o predom?nio da marca??o difusa. A imunoexpress?o citoplasm?tica/membranar do GLUT-1 exibiu uma correla??o estatisticamente significativa com o estadiamento cl?nico (p = 0,002) e grada??o histol?gica (p = 0,000). Em rela??o ? localiza??o de marca??o para o GLUT-1 na ilha tumoral, evidenciou-se predom?nio da marca??o perif?rica na maioria dos esp?cimes de baixo grau (78,6%). Na amostra de alto grau, prevaleceu a localiza??o centro/periferia (55,8%). De acordo com o teste qui-quadrado (Qui2), a localiza??o na ilha tumoral (p = 0,025) demonstrou haver diferen?as estatisticamente significativas com a grada??o histol?gica. A imunoexpress?o da CA-IX, localizada na maioria dos casos na membrana e citoplasma, exibiu uma correla??o estatisticamente significativa com a grada??o histol?gica (p = 0,005). Com base nestes resultados, pode-se concluir uma ampla participa??o desses marcadores de hip?xia na carcinog?nese oral, bem como a sua poss?vel utiliza??o como marcadores do comportamento biol?gico e da progress?o tumoral em CEL

Submitted by Edineia Teixeira (edineia.teixeira@unioeste.br) on 2017-12-18T18:47:09Z No. of bitstreams: 2 Caroline_Covatti2016.pdf: 1272706 bytes, checksum: 2b328da4ea5385205d047b1e31662783 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-12-18T18:47:09Z (GMT). No. of bitstreams: 2 Caroline_Covatti2016.pdf: 1272706 bytes, checksum: 2b328da4ea5385205d047b1e31662783 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-06-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Cerebral palsy (CP) is characterized by movement and postural disorders that limit the individual‘s activity, and is attributed to the occurrence of non-progressive disturbances during the development of the fetal or infant brain. Animal models have been used in an attempt to reproduce the lesions and characteristics of CP. However, there is still no intervention capable of reproducing the characteristics of this pathology in the experimental area. Thus, the objective of this study was to verify the effects of a CP model that combines prenatal exposure to lipopolysaccharide (LPS), perinatal anoxia and sensorimotor restriction on the muscle fibers and neuromuscular junctions (NMJs) of the extensor digitorum longus (EDL) of rats. Male Wistar pups were separated into two groups: Control group (CTL - n = 10) - pups of mothers injected with saline during pregnancy and Cerebral Palsy Group (CP - n = 10) - pups of mothers injected with LPS during pregnancy. submitted to perinatal anoxia and sensorimotor restriction. On the day of birth, the offspring of the CP group were placed in a closed chamber with nitrogen flow (100%) to perform the perinatal anoxia. Additionally, from the first postnatal day (P1) to P30, those pups were also submitted to sensorimotor restriction by immobilizing the hind limbs. Motor performance was assessed in both groups during open field tests on P29 and P45. After euthanasia, EDL muscle samples were processed for morphological and morphometric analysis of the muscle fibers and NMJs. Regarding motor performance, the time of locomotion and the number of rearings were significantly lower in the CP group compared to CTL group at 29 days of age (p <0.001 and p <0.01, respectively). At 45 days of age, the time of locomotion of the animals in the CP group was also lower in relation to the CTL group (p <0.05). The total body weight, weight and length of the EDL muscle were 18%, 17% and 15% lower, respectively, in the CP group in relation to the CTL. The animals in the CP group presented hypertrophy of the type IIB fibers. However, regarding the other fibers there was no difference between groups. There were no differences between groups in the number of muscle fiber types I, IIA and IIB. The nuclei/fiber ratio, and the capillary/fiber ratio, were significantly higher in the CP group (21% and 18%, respectively). Regarding the intrafusal fibers, the animals from the CP group presented atrophy in 26% of the cross-sectional area and a reduction of 26% in the muscle spindle area. Intramuscular collagen increased by 34% in the animals from the CP group. The ultrastructural study of the EDL muscle in the CP group showed myofibrillar disruption and Z-line disorganization and dissolution. The NMJs in the CP group presented an increase of 22% in area and 11% in diameter when compared to the CTL group. In conclusion, the CP animal model that uses injections of LPS, perinatal anoxia and sensorimotor restraint produces motor deficits that are also observed in children with CP. / A paralisia cerebral (PC) caracteriza-se por desordens do movimento e da postura, por isso causam limitação na atividade do indivíduo, as quais são atribuídas por distúrbios não progressivos que ocorreram no desenvolvimento cerebral fetal ou infantil. Modelos animais têm sido utilizados na tentativa de reproduzir as lesões e características da PC. Porém, ainda não existe uma intervenção capaz de reproduzir as características desta patologia no âmbito experimental. Assim, o objetivo deste estudo foi verificar os efeitos de um modelo de PC que associa exposição pré-natal ao lipopolissacarídeo (LPS), anóxia perinatal e restrição sensório-motora sobre as fibras musculares e junções neuromusculares (JNMs) do músculo extensor longo dos dedos (EDL) de ratos. Filhotes Wistar machos foram separados em dois grupos: Grupo controle (CTL - n = 10) - filhotes de mães injetadas com solução salina durante a gestação e Grupo Paralisia Cerebral (PC - n = 10) - filhotes de mães injetadas com LPS durante a gestação, submetidos à anóxia perinatal e à restrição sensório-motora. No dia do nascimento, os filhotes do grupo PC foram colocados em câmara fechada com fluxo de nitrogênio (100%) para a realização da anóxia perinatal. A partir do primeiro dia pós-natal (P1) até o P30, esses filhotes também foram submetidos à restrição sensório-motora por imobilização das patas pélvicas. Avaliações do desempenho motor foram realizadas em um campo aberto no P29 e P45 para os dois grupos. Após a eutanásia, amostras do músculo EDL foram processadas para análise morfológica e morfométrica das fibras musculares e JNMs. Quanto à performance motora, o tempo de locomoção e o número de erguidas (rearing) foi significativamente menor no grupo PC em comparação ao CTL aos 29 dias de idade (p< 0,001 e p< 0,01, respectivamente). Aos 45 dias de idade, o tempo de locomoção dos animais do grupo PC também foi menor em relação ao grupo CTL (p < 0,05). O peso corporal, peso e comprimento do músculo EDL foram 18%, 17% e 15% menores, respectivamente, no grupo PC em relação ao CTL. Os animais do grupo PC apresentaram hipertrofia das fibras do tipo IIB, todavia, não houve diferença entre os grupos nas demais fibras. Não teve diferenças entre os grupos estudados quanto ao número de fibras musculares dos tipos I, IIA e IIB. A relação núcleo/fibra, e a relação capilar/fibra, foi significativamente maior no grupo PC (21% e 18%, respectivamente). Quanto às fibras intrafusais, os animais do grupo PC apresentaram atrofia de 26% na área de secção transversal e redução de 26% na área do fuso muscular. O colágeno intramuscular aumentou 34% nos animais do grupo PC. O estudo ultraestrutural do músculo EDL do grupo PC mostrou desarranjo miofibrilar, desorganização e dissolução da linha Z. As JNMs do grupo PC apresentaram aumento de 22% na área e de 11% no diâmetro maior quando comparado ao grupo CTL. Em conclusão, o modelo animal de PC que utiliza injeções de LPS, anóxia perinatal e restrição sensório-motora produz déficits motores que também são observados em crianças com PC.

Na atualidade, uma das causas importantes de lesão encefálica em neonatos é a anóxia neonatal. Este é um problema grave nos serviços de perinatologia dos hospitais em todo o mundo sendo ainda pior em países subdesenvolvidos, devido à carência de precauções e cuidados requeridos. Modelos animais de anóxia vêm sendo empregados para avaliar seus efeitos, tanto em nível neurológico, como em nível comportamental. A anóxia neonatal tem sido estudada pelo laboratório de Neurociências do Instituto de Ciências Biomédicas da Universidade de São Paulo, com modelos de estudo já desenvolvidos, adaptados e validados. Para investigar se a anóxia neonatal afeta o desenvolvimento motor somático e sensorial, ratos foram submetidos a um modelo não invasivo de anóxia global (Takada et. al., 2011). Ratos Wistar com 30 h de idade (6-8 gramas), machos e fêmeas, foram expostos por 25 minutos a gás nitrogênio 100% num fluxo de 3L/min, pressão 101.7 kPa e temperatura de 37ºC em câmara semi-hermética de policarbonato. O grupo controle foi submetido às mesmas condições porem com o ar ambiente normal. Os animais foram avaliados durante o período de aleitamento (P2 a P21) quanto a parâmetros do desenvolvimento somático; desenvolvimento ontogenético e quanto a reflexos sensório motores. Os resultados indicaram que o grupo Anoxia macho(AM) apresentou aumento no peso corporal {AM(42.25±3.62);CM(38.76±5.60);AF(40.64±5.08);CF(41.33±5.45)}e diminuição do eixo longitudinal do corpo {AM(10.15±0.27);CM(10.39±0.50);AF(9.82±0.44);CF(10.82±0.46)} em relação ao grupo Controle macho(CM) e Anoxia fêmea(AF), AF foi menor em relacao ao Controle fêmea (CF). AM apresentou maior eixo látero-lateral do crânio em relação CM e AF {AM (3.18 ±0.10); CM (3.17 ±0.13); AF(3.06 ±0.16); CF(3.00 ±0.15)} No desenvolvimento ontogenético houve retardo na abertura do canal auditivo {AM (13.79± 0.58); CM (13.75±0.83); AF(14.21±1.01); CF(13.36±0.50)} e abertura dos olhos {AM (14.00± 0.88); CM (14.64±1.28); AF(15.14±0.86); CF(13.79±0.42)} no grupo AF em relação a CF e AM, mas no grupo AM não houve diferença significante. Na erupção dos incisivos superiores {AM (10.79± 0.43); CM(11.71±1.68); AF(11.43±0.65); CF(10.07±0.27)} o grupo AM adiantou enquanto o AF atrasou em relação ao grupo controle. A avaliação dos reflexos sensóriais mostrou que a anoxia adiantou a colocação pelas vibrissas {AM (8.80± 1.21); CM (9.50±1.56); AF (9.93±1.14); CF(10.14±1.28) no AF e AM. Apenas o AM adiantou {AM (10.93± 2.09); CM(13.43±0.94); AF(10.50±0.85); CF(9.57±0.76)} no reflexo de aversão ao precipício. Nos relfexos de geotaxia negativa {AM (14.87± 1.30); CM (13.57±2.34); AF(14.57±1.40);CF (12.00±2.11)} e sobressalto ao susto {AM (14.00±0.53); CM (13.21±1.31); AF (13.29±0.61); CF (11.93±0.27)} e preensão palmar {AM (6.60±0.83); CM (4.71±0.47); AF(10.14±0.83); CF(4.71±0.47)} a anóxia provocou atraso tanto em macho quanto em fêmeas motores. Houve atraso na ontogênese da maioria dos testes de reflexos dos filhotes do grupo Anóxia. Os resultados deste estudo demonstraram que a anóxia causa danos persistentes na maioria dos parâmetros avaliados em relação aos grupos controle, e diminuição no número de neurônios do córtex sensóriomotor {M2: AM (46.84±1.72); CM (52±1.66); AF (45.55±1.80); CF (52±1.55)M1: AM (23.70±1.33); CM (41.89±1.49); AF (25.69±0.83); CF (43.88±1.46) S1HL: AM (27.93±2.69); CM (30.19±1.31); AF(23.42±2.38); CF (38.88±1.48) S1FL: AM (31.85±1.09); CM (33.88±0.48); AF(27.66±1.36); CF(32.28±1.70)}, com diferença de gênero o que evidencia a importância de que estratégias e procedimentos para minimizar os efeitos desse estímulos sejam consideradas em relação ao gênero / At present, one of the important causes of brain injury is the neonatal anoxia. This is a serious problem in the perinatology services of hospitals around the world being even worse in underdeveloped countries because of the lack of precautions and care required. Animal models of anoxia have been employed to assess their effects, both at the neurological level and at the behavioral level. Neonatal anoxia has been studied by the Neuroscience Laboratory of the Biomedical Sciences Institute of the University of São Paulo, with animal models already developed, adapted and validated. To investigate whether neonatal anoxia affects somatic and sensory motor development, rats were subjected to a non-invasive model of global anoxia (Takada et al., 2011). Male and female 30-h old (6-8 grams) Wistar rats were exposed for 25 minutes to 100% nitrogen gas in a flow of 3 L/min, pressure 101.7 kPa and temperature of 37ºC in a semi-hermetic chamber of polycarbonate. The control group was subjected to the same conditions but with normal ambient air. The animals were evaluated during the lactation period (P2 to P21) for parameters of somatic development; Ontogenetic development and for sensorimotor reflexes. The results indicated that the male Anoxia (AM) group presented increase in body weight (AM (42.25 ± 3.62), CM (38.76 ± 5.60), FA (40.64 ± 5.08), CF (41.33 ± 5.45)) and decrease in the longitudinal (10.82 ± 0.46), in relation to the male control group (CM) and the female Anoxia (AF), AF was lower in relation to the control group (AM) (10.15 ± 0.27), CM (10.39 ± 0.50), AF (9.82 ± 0.44) Female control (CF). AM increase in the cranio-lateral axis in relation to CM and AF (AM (3.18 ± 0.10); CM (3.17 ± 0.13); AF (3.06 ± 0.16); CF (3.00 ± 0.15). Concerning the ontogenetic development there was delay in opening the (13.79 ± 0.58), and the eyes {AM (14.00 ± 0.88); CM (14.64 ± 1.28), AF (15.14 ± 0.86), CF (13.79 ± 0.42)} in the AF group in relation to CF and AM, but in the AM group there was no significant difference. In the eruption of maxillary incisors (AM (10.79 ± 0.43), CM (11.71 ± 1.68), AF (11.43 ± 0.65), CF (10.07 ± 0.27), the AM group advanced while the AF delayed in control ration. The evaluation of the sensory reflexes showed that anoxia improved the placement of vibrissae (AM (8.80 ± 1.21), CM (9.50 ± 1.56), AF (9.93 ± 1.14), CF (10.14 ± 1.28) in AF and AM. Only AM advanced (AM (10.93 ± 2.09), CM (13.43 ± 0.94), AF (10.50 ± 0.85), CF (9.57 ± 0.76) in the reflex of aversion to the precipice. In negative geotaxia relays (AM (14.87 ± 1.30); CM (13.57 ± 2.34), AF (14.57 ± 1.40), CF (12.00 ± 2.11)} and startle reflex {AM (14.00 ± 0.53); CM (13.21 ± 1.31); AF (13.29 ± 0.61); CF (11.93 ± 0.27) and palmar grip (AM (6.60 ± 0.83); CM (4.71 ± 0.47), AF (10.14 ± 0.83), CF (4.71 ± 0.47)), anoxia caused delay in both male and female groups. There was a delay in the ontogenesis of most of the reflex tests of the puppies of the anoxia group. The results of this study demonstrated that anoxia causes persistent damage in most of the parameters evaluated in relation to the control groups, and a decrease in the number of sensory motor cortex neurons (M2: AM (46.84 ± 1.72), CM (52 ± 1.66), AF 1.80), CF (52 ± 1.55) M1: AM (23.70 ± 1.33), CM (41.89 ± 1.49), AF (25.69 ± 0.83), CF (43.88 ± 1.46) S1HL: AM (27.93 ± 2.69), CM (30.19 (31.88 ± 1.48), FA (27.66 ± 1.36), CF (32.28 ± 1.70), , which shows that strategies and procedures to minimize the effects of such stimuli should be considered in relation to gender

Climate change is one the greatest environmental challenges of our time, both due to direct eectssuch as global warming but also due to the potential of the climate acting as a driver for otherenvironmental problems. This thesis aims to evaluate the impact of climate change on thermal properties and the content and distribution of dissolved oxygen in boreal lakes. By calibrating the one-dimensional, process based model MyLake with data from three, long-time monitored lakes in Sweden, vertical proles of temperature and oxygen could be studied over time. Changes in air temperature, precipitation and discharge showed to have a great impact on the thermal properties of the lakes. Simulations 30 and 80 years in the future with high impact climate scenarios indicated an overall increase in lake water temperature and reduced duration of icecover. The increase in lake water temperature decreased with depth, indicating enhanced thermal stratication. Climate change also had a profound impact on the content and distribution of dissolved oxygen, DO, in the lakes. Climate-induced increases in dissolved organic carbon, DOC, had an overall negative impact on the DO content in the water column. The impact of changes in air temperature, precipitation and discharge however had an overall positive impact on lake water DO, most likely due to increased oxygen supply during the winter months due to the shorter duration of ice cover. The risk of summer anoxia increased due to the combined effect of increased air temperatures and elevated DOC concentrations. In conclusion, the impact of climate change will, directly or indirectly, have a profound impacton both the thermal conditions and the content and distribution of oxygen in lakes. This may drastically change future lake water quality as well as the living conditions for the aquatic life. / De pågaende klimatförändringarna är ett av vår tids mest utmanade miljöhot, dels påa grund av direkta effekter såsom global uppvärmning men också på grund av klimatets potential att agera som en drivande faktor i många miljösammanhang. Målet med denna studie var att undersöka hur klimatförändringarna påverkar temperatur- och syrgasgasförhallanden i sjöar. Genom att kalibreraden den dimensionella, processbaserade modellen MyLake, med data från tre svenska sjöar, kunde vertikala temperatur- och syrgasprofiler undersökas över tid. Förändringar i lufttemperatur, nederbörd och flöde, baserade pa vedertagna klimatscenarier med hög klimatpåverkan, visade sig ha en tydlig påverkan på sjörnas temperaturförhållanden. Simuleringar 30 och 80 år fram i tiden resulterade i forhöjda vattentemperaturer i hela vattenkolumnen samt förändringar i tidpunkt for isbildning och smältning. Vattentemperaturen ökade for samtliga undersökta djup, men ökningshastigheten minskade med ökat djup. Detta tyder på starkare skiktning av vattenkolumnen i framtiden. Förandringar i klimatet visade sig också ha en stor inverkan pa sjöarnas syrgasförhållanden. Ökande halter av löst organiskt kol, orsakade av klimatförändringar, hade negativ inverkan på sjöarnas syrgasförhållanden. Förändringar i lufttemperatur, nederbörd och flöde hade däremot en överlag positiv inverkan pa sjöarnas syrgasförhållanden. Detta beror troligtvis på att tillflödet av syrgas ökar i och med att tiden då sjön är täckt av is förkortas. Risken for syrefattiga förhållanden under sommarmånaderna ökade dock, på grund av den kombinerade effekten av förhöjd lufttemperatur och ökande DOC halter. Sammanfattningsvis förväntas klimatförändringar ha en tydlig effekt på både temperatur- och syrgasforhallanden i sjöar. Detta riskerar att avsevärt försämra både sjöarnas vattenkvalitet och levnadsförhållanden för vattenlevande organismer.

The consequences of early embryonic insults and how they affect subsequent life reflects the emerging concept of "fetal programming". The aim of this project is to study the effects of embryonic insults as they subsequently manifest themselves in adults, with emphasis on the heart and vasculature. My experiments establish that fetal programming operates on the bobwhite quail inducing similar changes as those observed in mammalians and other birds. The quail's fast development provides reliable data in a short period of time than other avian models (e.g. domestic chicken). Data on quail showed a correlation between egg mass and hatchling mass; where small eggs produce small hatchlings but a high mortality made it impractical as a stressor for this study. Hypoxia was used as a stressor during embryonic incubation, where it induced a low hatching weight in quail that was not observable in adult birds. Morphological measurements demonstrated an increased ventricular collagen content and reduced ventricular lumen in birds in adults incubated in hypoxia consistent with hypertension. The hematological analyzes showed few differences indicating organ remodeling instead of hematopoietic compensation. The assessment of vascular reactivity pointed out an impaired endothelium dependent relaxation commonly associated to hypertension in birds and mammals. Fetal programming could be a widespread response to an adverse prenatal environment in endotherms and the resulting data from this work contributes to our understanding of fetal programming in vertebrates and its long term consequences.

The mammalian adrenal gland (or suprarenal gland) is a small organ located on the superior aspect of the kidney. The central region of the gland, the medulla, consists of chromaffin cells, which release catecholamines into the blood during periods of stress. This is best known as the 'fight or flight' response and is regulated, in the adult animal, by neuronal signals from the cholinergic sympathetic fibres of the splanchnic nerve. Interestingly, in some mammals, such as rat and human, sympathetic innervation is immature at birth, yet the chromaffin cells can still secrete catecholamines in response to physiological stessors, e.g. hypoxia. Increased plasma catecholamines is thought to provide a vital protective role for the neonatal animal during, and following birth. This is mediated in part by promoting lung fluid absorption, surfactant secretion, heart rate stabilization, and brown fat mobilization. The observation that, in the neonate, catecholamines are secreted in the absence of functional sympathetic innervation suggests that the chromaffin cells possess other mechanisms for directly 'sensing' a fall in blood O2 tension (hypoxia). The primary goal of this thesis was to uncover the mechanisms of oxygen-sensing in developing chromaffin cells from the rat and mouse, using primary short-term cell cultures of chromaffin cells. The experimental approaches relied on patch clamp techniques to record ionic currents and membrane potential, carbon fibre electrochemistry to record catecholamine secretion from cell clusters, and fluorescent indicators to measure reactive oxygen species generation. Hypoxic chemosensitivity was found in embryonic and neonatal, but not juvenile chromaffin cells from both the rat and mouse. Exposure to hypoxia or anoxia caused a reversible suppression of whole-cell current, which was comprised of the differential modulation of three K+ currents: (1) suppression of a large-conductance Ca2+-dependent K+ current; (2) suppression of a delayed rectifier K+ current; and (3) activation of an ATP-sensitive K+ current. Hypoxia also induced membrane depolarization that was not initiated by any of these three voltage-dependent K+ currents. Additionally, hypoxia broadened action potentials in chromaffin cells that showed spontaneous activity, and this was mediated by a prolongation of the time course of membrane repolarization. All of these factors likely contribute to catecholamine secretion by enhancing the influx of Ca2+ through depolarization-activated L-type Ca2+ channels. Two sets of experiments were designed to identify the oxygen sensor in neonatal chromaffin cells. First, cells from transgenic mice, deficient in the gp91^phox component of the putative O2-sensor protein, NADPH oxidase, responded to hypoxia in the same way as wild type cell, indicating that NADPH oxidase is not primarily responsible for oxygen sensitivity in these cells. Second, inhibitors of the proximal electron transport chain (e.g. rotenone and antimycin A) mimicked and attenuated the hypoxic response, while inhibitors of the distal electron transport chain (cyanide) and uncouplers of oxidative phosphorylation (2,4-dinitrophenol) had no effect. Furthermore, reactive oxygen species production, primarily H2O2, decreased during exposure to hypoxia or inhibitors of the proximal electron transport chain, revealing a potential mitochondrial mechanism for 'sensing' of the hypoxic stimulus. Reduced oxygen availability to the electron transport chain is proposed to cause a fall in cellular reactive oxygen species (ROS), principally H2O2. This fall in ROS signals closure of Ca2+-dependent and Ca2+-independent K+ channels, which causes broadening action potentials and increases Ca2+ influx. The latter is further enhanced by the hypoxia-induced membrane depolarization, which in turn increases the probability of cell firing. The rise in intracellular Ca2+ then acts as the signal for catecholamine release from the chromaffin cells. / Thesis / Doctor of Philosophy (PhD)