Made available in DSpace on 2015-07-22T20:49:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-10-28 / Ha evidencias de que o fluxo microvascular de oxigenio (QO2mv) limita a taxa de aumento da captacao de oxigenio ( O2) no inicio do exercicio intenso em pacientes com doenca pulmonar obstrutiva cronica (DPOC). Entretanto, ainda nao esta claro se a suplementacao de O2 poderia acelerar a cinetica do O2 atraves da melhora do QO2mv em pacientes nao-hipoxemicos ou levemente hipoxemicos. Assim, o objetivo do estudo foi investigar se a suplementacao aguda de O2 (HiOX=50%O2) poderia alterar a dinamica entre oferta e O2 microvascular na transicao do exercicio leve para o intenso, alem de avaliar se os possiveis efeitos da HiOX na oxigenacao tecidual tissular teriam efeito modulador na cinetica da utilizacao muscular de O2. Para tal, foram avaliados 19 pacientes do sexo masculino, nao-hipoxemicos ou levemente hipoxemicos (PaO2>60mmHg) portadores de DPOC de gravidade moderada a acentuada (VEF1/CVF < 0,7 e VEF1 entre 30 e 60% do previsto) e estaveis clinicamente, durante exercicio submaximo de alta intensidade (80% da maxima atingida no exercicio incremental em cicloergometro). Neste contexto, foram investigados os efeitos da HiOX em comparacao com normoxia (NOX = 21% O2) na cinetica do O2 mensurado em nivel pulmonar (p) e da extracao fracional de O2 (HHb mensurada pela espectroscopia por raios quase infravermelhos - NIRS) no vasto lateral. A HiOX esteve associada com aumento na tolerancia ao exercicio (p<0,05) alem de reducao da concentracao de lactato, sensacao de dispneia e desconforto muscular corrigidos para o tempo de duracao do exercicio (Tlim) (N=19). Nos 11 individuos com sinais adequados para estudo da cinetica, a extracao fracional de O2 estimada acelerou-se (DHHb: t= 4.8 } 2.4 s vs. 6.7 } 3.0 s; P<0.05) e um subsequente fenomeno de govershoot h foi observado em 7/11 pacientes, sugerindo prejuizo no QO2mv. Entretanto, durante o periodo estado-estavel, houve reducao dos valores de HHb em 9/11 pacientes sugerindo melhora do QO2mv. Como consequencia desse efeito dual da HiOX no QO2mv (i.e, reducao seguida de melhora), a cinetica do O2p foi acelerada em 6 pacientes mas lentificada em outros 5 pacientes. De forma interessante, observamos que pacientes que apresentaram aceleracao da cinetica do O2p com HiOX tambem apresentaram maiores reducoes dos valores de DHHb no estado-estavel comparados aos demais pacientes (HiOX . NOX= -23.4 (-55.5 to -5.8) ƒÊM/cm vs. -0.62 (-22.6 to 10.7) ƒÊM/cm; p<0.05). Adicionalmente, houve correlacao significativa entre reducao dos valores de DHHb no estado-estavel e aceleracao na cinética do O2 com HiOX (R= 0.61; p<0.05). Em conclusão, HiOX melhorou a tolerância ao exercício físico, além de ter resultado em redução significativa da dispnéia, percepção de fadiga periférica e lactato corrigidos pelo tempo de exercício em pacientes com DPOC não-hipoxêmicos ou levemente hipoxêmicos. Entretanto, nosso resultados indicam que houve prejuízo transitório no QO2mv no início do exercício, que foi compensado por melhora subseqüente, justificando assim os efeitos heterogêneos do O2 na cinética do O2p. Portanto, as consequências da HiOX na taxa de aumento do metabolismo oxidativo no início do exercício intenso nessa sub-população de pacientes parece depender de um complexo balanço entre os efeitos negativos iniciais no fluxo sanguíneo microvascular e as posteriores conseqüências positivas nos determinantes difusivos e/ou convectivos do transporte capilar-muscular de O2. / There is convincing evidence that impaired microvascular O2 delivery (Q LO2mv) to the peripheral muscles limits the rate of increase in pulmonary O2 uptake ( O2p) at the onset of supra-gas exchange threshold exercise in patients with chronic obstructive pulmonary disease (COPD). It is currently unclear, however, whether O2 supplementation could actually improve Q LO2mv thereby accelerating O2p kinetics in patients who are not overtly hypoxemic (PaO2 > 60 mmHg). We therefore investigated the effects of hyperoxia (HiOX= 50% O2) and normoxia (NOX) on the kinetics of O2p and fractional O2 extraction in the vastus lateralis ( [deoxy- Hb+Mb] by near-infrared spectroscopy) in 11 non- or mildly-hypoxemic patients. HiOX increased exercise tolerance compared to NOX (P<0.05). At the on-exercise transient, however, HiOX was associated with faster [deoxy-Hb+Mb] kinetics (= 4.8 } 2.4 s vs. 6.7 } 3.0 s; P<0.05) and a response govershoot h in 7/11 patients suggesting impaired Q LO2mv. Subsequently, however, [deoxy-Hb+Mb] decreased to lower steady-state values compared to NOX in 9/11 patients (P<0.05). As a likely consequence of these opposite effects of HiOX on Q LO2mv (i.e., early impairment followed by later improvement), O2p kinetics were accelerated in 6 but slowed in 5 patients. Interestingly, patients in whom HiOX accelerated O2p kinetics showed consistently-larger reductions in gsteady-state h ..[deoxy-Hb+Mb] compared to their counterparts (HiOX . NOX= -23.4 (-55.5 to -5.8) ƒÊM/cm vs. -0.62 (-22.6 to 10.7) ƒÊM/cm; p<0.05). In conclusion, HiOX can transitorily impair the convective flow of O2 to the working peripheral muscles at the onset of heavy intensity exercise in patients with COPD who are not overtly hypoxemic. This effect, however, might be (over)compensated by a subsequent increase in local O2 availability in selected patients. These data seem to provide a mechanistic explanation for the heterogeneous effects of HiOX on O2p kinetics in this patient sub-population. / TEDE / BV UNIFESP: Teses e dissertações

In der Pathogenese der Temporallappenepilepsie wird kindlichen hippokampalen Schädigungen eine wesentliche Rolle zugeschrieben. Epileptische Krämpfe und perinatale Asphyxie sind zwei häufige Ursachen dieser Schädigungen. Anhaltende epileptiforme Aktivität im Niedrig-Mg2+-Modell als einer experimentellen Form epileptischer Krämpfe führt in organotypischen hippokampalen Schnittkulturen (OHSK) der Ratte, die als Ersatzsystem des kindlichen Hippokampus verwendet werden, zu Zellschäden. Während dieser Untersuchungen ergab sich der Verdacht auf eine zusätzlich schädigende Wirkung erhöhter Sauerstoffspannungen. In meiner ersten Versuchsreihe konnte ich nachweisen, dass erhöhte Sauerstoffspannungen (60 %, 95 %) verglichen mit 20%-Sauerstoffspannung zu reversiblen und irreversiblen Zellschäden in OHSK führen. Die Zellschäden wurden über Veränderungen reizinduzierter Feldpotentiale, d.h. Abnahme der Amplitude, Zunahme der Latenz und Zunahme des Doppelpulsindex, sowie über die Propidium Jodid (PJ)-Fluoreszenzintensität bestimmt. In der zweiten Versuchsreihe konnte gezeigt werden, dass erhöhte Sauerstoffspannungen auch nach einer Hypoxie im Sinne einer hyperoxischen Reoxygenierung verglichen mit normoxischer Reoxygenierung vermehrt Zellschäden in OHSK zur Folge haben. In der dritten Versuchsreihe konnte ich ausschließen, dass erhöhte Sauerstoffspannungen eine notwendige Bedingung für Zellschäden infolge anhaltender epileptiformer Aktivität sind. Um die zellschädigende Rolle von Spreading Depressions (SDs), die während epileptiformer Aktivität auftreten, zu bestimmen, wurde in der vierten Versuchsreihe eine Methode etabliert, SD-ähnliche Ereignisse isoliert und zuverlässig in normoxischen OHSK auszulösen. Auf diese Weise wiederholt ausgelöste SD-ähnliche Ereignisse führten zu Zellschäden, bestimmt über die Veränderung elektrophysiologischer Eigenschaften von SD-ähnlichen Ereignissen, Abnahme der Feldpotentialamplitude und PJ-Fluoreszenzintensität. / Hippocampal damage during infancy is thought to play an important role in the pathogenesis of temporal lobe epilepsy. Epileptic seizures and perinatal asphyxia are two frequent causes of these damages. Sustained epileptiform activity induced in the low Mg2+-model of epileptic seizures leads to cell damage in organotypic hippocampal slice cultures (OHSC) of the rat, which are used as a surrogate for the infantile hippocampus. During a previous study utilising this model the suspicion arose that increased oxygen tension could have an additional damaging effect. My first series of experiments proved that increased oxygen tension (60 %, 95 %) lead to reversible and irreversible cell damage in OHSC compared to 20%-oxygen tension. Cell damage was determined by alterations of evoked field potentials, i.e. decrement of amplitude, increment of latency and paired pulse index, as well as by propidium iodide fluorescence. The second series of experiments showed that increased oxygen tension applied after an hypoxic period (hyperoxic reoxygenation) result in augmented cell damage compared to normoxic reoxygenation. With the third series of experiments it could be excluded that increased oxygen tension is an essential condition for the occurrence of cell damage due to sustained epileptiform activity. In order to elucidate the damaging role of spreading depressions (SD), which emerge during epileptiform activity, a method was established in the fourth series of experiments that allowed the reliable induction of SD-like events in normoxic OHSC. Repetitive SD-like events induced by this method led to cell damage, assessed by alterations of electrophysiological characteristics of SD-like events, decrement of evoked field potential amplitude and propidium iodide fluorescence.

Die rasanten Fortschritte in der neonatalen Intensivmedizin haben zwar die Ueberlebenschancen von Fruehgeborenen enorm verbessert, aber auch viele Probleme und Fragen aufgeworfen. In dieser Arbeit wurde untersucht, ob Hyperoxie Einfluss nimmt auf die Expression von apoptotischen Genen, Wachstumsfaktoren und Zytokinen und so ueber verschiedene Mechanismen und Signalwege zu einem Ungleichgewicht der ueber das neuronale Ueberleben entscheidenden Faktoren fuehrt. 6-Tage alte Ratten wurden fuer bestimme Zeitabschnitte (2, 6, 12, 24, 48, 72 Stunden) einer 80%igen Sauerstoffkonzentration ausgesetzt. In dieser Arbeit konnte am unreifen Rattengehirn nachgewiesen werden, dass eine 80%ige Sauerstoffkonzentration in der Atemluft maximal nach 12 bis 24 Stunden zu einer ausgepraegten, diffusen apoptotischen Neurodegeneration im Gehirn fuehrt. Die Exposition mit hoher Sauerstoffkonzentration fuehrte im unreifen Gehirn zu einer deutlich verminderten Expression der Neurotrophinen, wie deren Signalproteine ERK 1/2 und Akt. Als spezifischer Nachweis fuer eine apoptotische Neurodegeneration wurden neben dem histologischen Verfahren auf molekularer Ebene apoptotische Gene untersucht. Unter Hyperoxie kam es zu einer erhoehten Expression des Todesrezeptors Fas und einer gesteigerten Aktivitaet von Caspase-3.Des Weiteren fand sich infolge der Hyperoxieexposition ein drastischer Anstieg der inflammatorischen Zytokine IL-1beta und IL-18. Es zeigt sich also, dass hohe Sauerstoffkonzentrationen in einer sehr vulnerablen Phase der Hirnentwicklung (Phase des rapiden Hirnwachstums) zu massiven Veraenderungen fuehren, welche den bisher ungeklaerten diffusen Neuronenuntergang bei Fruehgeborenen erklaeren koennten. Die vorliegenden Ergebnisse implizieren aeu§erste Vorsicht bei der therapeutischen Anwendung von Sauerstoff bei Fruehgeborenen, fuer die die postnatalen Konditionen, verglichen mit den intrauterinen Bedingungen, immer hyperoxisch sind und die noch ueber ein unreifes Antioxidationssystem verfuegen. / Infants born prematurely may develop neurocognitive deficits without an obvious cause. Oxygen, which is widely used in neonatal medicine, constitutes one possible contributing neurotoxic factor, because it can trigger neuronal apoptosis in the developing brain of rodents. Premature infants are exposed to partial oxygen pressures that are fourfold higher compared to intrauterine conditions, even if no supplemental oxygen is administered. Here is reported that short exposures to nonphysiologic oxygen levels can trigger apoptotic neurodegeneration in the developing brain. Vulnerability to oxygen neurotoxicity is confined to the first 2 weeks of life, a period characterized by rapid growth, which in humans expands from the sixth month of pregnancy to the third year of life. Hyperoxia caused decreased expression of neurotrophins, and inactivation of survival signalling proteins extracellular signal-regulated kinase (ERK1/2), and protein kinase B (Akt). In addition we hypothesized that two caspase-1-processed cytokines, interleukin (IL)-1beta and IL-18, are involved in oxygen-induced neuronal cell death. Six-day-old Wistar rats were exposed to 80% oxygen for various time periods (2, 6, 12, 24, 48, 72 hours). Neuronal cell death in the brain, as assessed by silver staining, peaked at 12 to 24 hours and was preceded by a marked increase in mRNA of IL-1beta, IL-18 and FAS and a decrease in mRNA and protein levels of neurotrophins and ERK1/2 and Akt Our findings reveal mechanisms that could potentially damage the developing brain of human premature neonates.

The BOLD contrast employed in functional MRI studies is an ambiguous signal composed of changes in blood flow, blood volume and oxidative metabolism. In situations where the vasculature and metabolism may have been affected, such as in aging and in certain diseases, the dissociation of the more physiologically-specific components from the BOLD signal becomes crucial. The latest generation of calibrated functional MRI methods allows the estimation of both resting blood flow and absolute oxygen metabolism. The work presented here is based on one such proof-of-concept approach, dubbed QUO2, whereby taking into account, within a generalized model, both arbitrary changes in blood flow and blood O2 content during a combination of hypercapnia and hyperoxia breathing manipulations, yields voxel-wise estimates of resting oxygen extraction fraction and oxidative metabolism. In the first part of this thesis, the QUO2 acquisition protocol and data analysis were revisited in order to enhance the temporal stability of individual blood flow and BOLD responses, consequently improving reliability of the model-derived estimates. Thereafter, an assessment of the within and between-subject variability of the optimized QUO2 measurements was performed on a group of healthy volunteers. In parallel, an analysis was performed of the sensitivity of the model to different sources of random and systematic errors, respectively due to errors in measurements and choice of assumed parameters values. Moreover, the various impacts of the oxygen concentration administered during the hyperoxia manipulation were evaluated through a simulation and experimentally, indicating that a mild hyperoxia was beneficial. Finally, the influence of Alzheimer’s disease in vascular and metabolic changes was explored for the first time by applying the QUO2 approach in a cohort of probable Alzheimer’s disease patients and age-matched control group. Voxel-wise and region-wise differences in resting blood flow, oxygen extraction fraction, oxidative metabolism, transverse relaxation rate constant R2* and R2* changes during hypercapnia were identified. A series of limitations along with recommended solutions was given with regards to the delayed transit time, the susceptibility artifacts and the challenge of performing a hypercapnia manipulation in cohorts of elderly and Alzheimer’s patients. / Le contraste BOLD employé dans les études d’imagerie par résonance magnétique fonctionnelle (IRMf) provient d’une combinaison ambigüe de changements du flux sanguin cérébral, du volume sanguin ainsi que du métabolisme oxydatif. Dans un contexte où les fonctions vasculaires ou métaboliques du cerveau ont pu être affectées, tel qu’avec l’âge ou certaines maladies, il est crucial d’effectuer une décomposition du signal BOLD en composantes physiologiquement plus spécifiques. La dernière génération de méthodes d’IRMf calibrée permet d’estimer à la fois le flux sanguin cérébral et le métabolisme oxydatif au repos. Le présent travail est basé sur une telle technique, appelée QUantitative O2 (QUO2), qui, via un model généralisé, prend en considération les changements du flux sanguin ainsi que ceux en concentrations sanguine d’O2 durant des périodes d’hypercapnie et d’hyperoxie, afin d’estimer, à chaque voxel, la fraction d’extraction d’oxygène et le métabolisme oxydatif au repos. Dans la première partie de cette thèse, le protocole d’acquisition ainsi que la stratégie d’analyse de l’approche QUO2 ont été revus afin d’améliorer la stabilité temporelle des réponses BOLD et du flux sanguin, conséquemment, afin d’accroître la fiabilité des paramètres estimés. Par la suite, une évaluation de la variabilité intra- et inter-sujet des différentes mesures QUO2 a été effectuée auprès d’un groupe de participants sains. En parallèle, une analyse de la sensibilité du model à différentes sources d’erreurs aléatoires (issues des mesures acquises) et systématiques (dues aux assomptions du model) a été réalisée. De plus, les impacts du niveau d’oxygène administré durant les périodes d’hyperoxie ont été évalués via une simulation puis expérimentalement, indiquant qu’une hyperoxie moyenne était bénéfique. Finalement, l’influence de la maladie d’Alzheimer sur les changements vasculaires et métaboliques a été explorée pour la première fois en appliquant le protocole QUO2 à une cohorte de patients Alzheimer et à un groupe témoin du même âge. Des différences en terme de flux sanguin, fraction d’oxygène extraite, métabolisme oxydatif, et taux de relaxation transverse R2* au repos comme en réponse à l’hypercapnie, ont été identifiées au niveau du voxel, ainsi qu’au niveau de régions cérébrales vulnérables à la maladie d’Alzheimer. Une liste de limitations accompagnées de recommandations a été dressée en ce qui a trait au temps de transit différé, aux artéfacts de susceptibilité magnétique, de même qu’au défi que représente l’hypercapnie chez les personnes âgées ou atteintes de la maladie d’Alzheimer.

Aim The main aim of this study was to investigate the longitudinal effects on cycling performance using a polarized and periodized scheme that was highly supervised and controlled. The second aim was to investigate the effect of using Hyperoxia. The questions used to address the aim were: (1) How does overall performance change after a six-week training intervention? (2) What is the time-course and pattern of performance changes to the training scheme? (3) How does the performance change within the groups?   Method Nineteen male and female cyclists started the study (13 male and 6 female), however only 12 completed it (8 male and 4 female). The characteristics for the 12 subjects were:  age (year) 33.6 ± 6.8, height (cm) 177 ± 9.1, body mass (kg) 73.4 ± 8.8. Using a randomized, double blind design, the test subjects were divided in to hyperoxia (HOT) (n = 6) and normoxia (NOT) (n = 6) training groups.  Over a six week period the subjects followed a controlled polarized periodization that included 15 high intensity interval training (HIIT) sessions (3 x 8 min, 3 x 8 + 4 min, 4 x 8 min &amp; 4 x 4 min) on maximal sustainable intensity (isoeffort) on a cycle ergometer. The dosage of oxygen was administered intermittently by the oxelerate device. A 20 min all out test was performed as pre- and post test.    Results The whole group (n = 12) increased mean power output (W) by 6.4 % (P = 0.002). The relative power output (W/kg) increased significantly 8.2 % (P = 0.0011). The HOT group (n = 6) increased their power output by 8.3 % (P = 0.028) and their relative power output increased by 9.4 % (P=0.011). The whole group (P = 12) significantly increased their VO2mean by 4.1 % (P = 0.03) and in the relative value by 5.4 % (P = 0.01) on the 20 min all out test. The whole group also had a significant increase in VO2peak of 3.7 % (P = 0.04). A very strong correlation could be found between the training data and the performance test.   Conclusions The training intervention was favourable for increasing performance and VO2peak in cycling. Usage of hyperoxia during the training intervention increases the performance. / Syfte och frågeställningar Huvudsyftet med denna studie var att undersöka de longitudinella effekter på prestation i cykling med hjälp av ett polariserat och periodiserat träningsupplägg som var väl övervakat och kontrollerat. Det andra syftet var att undersöka effekten av att använda hyperoxi. De frågeställningar som hjälpte att besvara syftet var: (1) Hur förändras prestationen efter en sex veckors träningsintervention? (2) Hur anpassar sig försökspersonerna till träningsschemat över tid?  (3) Hur förändras prestationen inom grupperna?   Metod 19 manliga och kvinnliga cyklister deltog i studien (13 manliga och 6 kvinnliga), 12 fullföljde hela studien (8 manliga och 4 kvinnliga). Karaktäristiken för de 12 försökspersonerna var: ålder (år) 33.6 ± 6.8, längd (cm) 177 ± 9.1, vikt (kg) 73.4 ± 8.8. Försökspersonerna delades in i hyperoxi (HOT) (n = 6) och normoxi (NOT) (n = 6), studien var dubbelblind. Under sex veckor följde försökspersonerna en kontrollerad polariserad periodisering som inkluderade 15 högintensiva intervallträningspass (HIIT) (3 x 8 min, 3 x 8 + 4 min, 4 x 8 min &amp; 4 x 4 min) på högsta genomförbara intensitet (isoeffort) på cykelergometer. Doseringen av syre administrerades intermittent genom Oxelerate-enheten. Ett 20 min all-out test utfördes som för- och eftertest.   Resultat Hela gruppen (n = 12) ökade signifikant på prestationstestet (W) med 6.4 % (P = 0.002). Den relativa effekten (W/kg) ökade signifikant med 8.2% (P = 0.0011). HOT (n = 6) ökade signifikant på prestationstestet med 8.3% (P = 0.028) och den relativa effekten ökade med 9.4% (P = 0.011). Hela gruppen (n = 12) ökade signifikant i VO2medel under prestationstestet med 4.1 % (P = 0.03) och i det relativa värdet med 5.4 % (P = 0.01). Hela gruppen hade också en signifikant ökning av VO2peak med 3.7 % (P = 0.04). En mycket stark korrelation hittades mellan träningspassdata och prestationstestet.   Slutsats Träningsupplägget är gynnsamt för ökning av prestation och VO2peak i cykling. Användning av hyperoxi under träningsupplägget ökar prestationen.

Detection of early pathophysiological changes of breathing in children with chronic respiratory disease MD. Vaclav Koucky - Ph.D. thesis Abstract Introduction: Currently, there are different methods for infant pulmonary function testing (iPFT) and morphological assessment of microscopic changes in endobronchial biopsy samples (EBB). In research setting, they allow detection of early pathophysiological changes of breathing in small children with chronic respiratory disease, respectively in risk of its development. Their clinical significance, however, is not fully acknowledged. The aim of this thesis is to evaluate the safety, feasibility and clinical significance of iPFT and EBB in infants younger than 2 years of age. In addition, the relationship between functional and morphological changes of respiratory tract and the function of peripheral chemoreceptors was studied in selected patients' subgroups. Methods: Fifty-five infants with cystic fibrosis (CF), 35 physician-confirmed recurrent wheezers (AB), 9 infants with congenital diaphragmatic hernia, 7 with interstitial lung disease (chILD) and 3 with primary ciliary dyskinesia (PCD) were enrolled. All infants underwent iPFT and relevant clinical history data were recorded. Based on patients' age, CF group was divided into CFmalí (< 6 months) and CFvelcí (>...