Thesis (Ph. D.)--University of Notre Dame, 2006. / Thesis directed by Phillip R. Sloan and Ahmad Dallal for the Graduate Program in the History and Philosophy of Science. "December 2006." Includes bibliographical references (leaves 259-278).

This thesis addresses the problem of defining the control law for human respiration. Seven different drivers have been identified as possibly having an input to the respiratory controller. These seven represent a combination of feedforward and feedback inputs arising from neural and humoral mechanisms. Using the assumption that carbon dioxide concentrations in the arterial blood have the strongest effect, a control equation with proportional and derivative components based on this driver was evaluated. The methodology for the evaluation was to create a model of the respiratory system incorporating the P/D controller, obtain experimental data of one test subject's respiratory response to exercise, then compare model generated output with experimental data, and adjust the parameters in the control equation to yield optimal model performance. The usual practice of testing controller performance has been to apply single step loads to a model and evaluate its response. A multi-step protocol was used here to provide a better, more generalized test of controller performance. This thesis may represent the first documented use of an approach of this type for evaluating respiratory controller performance. Application of a multi-step protocol revealed a non-linear controller was needed to keep pace with system changes. Respiratory system operation was effectively managed using a controller of the form: VENTILATION = F(dCO₂/dT,Q) + F(CO₂,Q) + CONSTANT. / Master of Science

A digital simulation of the cardiovascular and pulmonary systems of a newborn infant was developed and tested. More specifically, the model was designed to emulate the blood gas chemistry of the neonate and it's effect on respiratory stimulus, cardiac output and Ductus Arteriosus shunting. Pulmonary and cardiac system dynamics were not considered in the simulation. The model underwent a series of tests in which controlled mockups of actual physiological conditions were simulated. The effect of metabolic rate changes, Ductus Arteriosus shunting, and alveolar membrane disease on the pulmonary and cardiovascular systems was studied in steady state conditions. The dynamic alterations in the neonatal system due to respirator therapy and carbon dioxide inhalation was investigated. Finally, a simulation of an actual clinical case was undertaken. While the model worked well in the controlled environment tests, it showed some deficiencies in the clinical case study. Additional clinical data is needed to improve the respiratory and cardiac control mechanisms in the simulation. Further, a more complete blood buffer system needs to be incorporated into the model. / M.S.

Zou Wei. / Thesis submitted in: December 2001. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 98-119). / Abstracts in English and Chinese. / Declaration --- p.i / Acknowledgements --- p.ii / Publication lists --- p.iii / Abstract --- p.ix / Abbreviations --- p.xiii / List of tables and figures --- p.xiv / Chapter Chapter 1: --- General Introduction --- p.1 / Chapter 1.1. --- Endothelium-dependent relaxation in coronary and pulmonary circulation --- p.1 / Chapter 1.1.1. --- Endothelium-derived relaxing factors --- p.2 / Chapter 1.1.1.1. --- Nitric Oxide --- p.3 / Chapter 1.1.1.2. --- PGI2 --- p.5 / Chapter 1.1.1.3. --- EDHF --- p.6 / Chapter 1.1.2. --- EDHF in coronary and pulmonary circulation --- p.8 / Chapter 1.1.2.1. --- EDHF in coronary circulation --- p.8 / Chapter 1.1.2.2. --- EDHF in pulmonary circulation --- p.9 / Chapter 1.2. --- Effect of hyperkalemia on EDHF-mediated relaxation --- p.10 / Chapter 1.3. --- Organ Preservation Solutions --- p.13 / Chapter 1.3.1. --- Euro-Collins solution --- p.14 / Chapter 1.3.2. --- University of Wisconsin solution --- p.15 / Chapter Chapter 2: --- Objectives and research approaches --- p.16 / Chapter 2.1. --- Objectives --- p.16 / Chapter 2.1.1. --- "Endothelium-dependent relaxation resistant to INDO, L-NNA, and HbO in porcine and pulmonary coronary micro-arteries" --- p.16 / Chapter 2.1.2. --- "EET11,12 and EDHF-mediated function in porcine coronary micro-arteries" --- p.17 / Chapter 2.1.3. --- "Comparison of EC or UW solution on endothelium-dependent relaxation resistant to INDO, l-NNA, and HbO in porcine pulmonary arteries" --- p.17 / Chapter 2.2. --- Research approaches --- p.18 / Chapter 2.2.1. --- "Endothelium-dependence of the relaxation by BK or EET11,12" --- p.18 / Chapter 2.2.2. --- Effect of hypothermic storage with EC and UW solution on EDHF-related relaxation --- p.18 / Chapter 2.2.3. --- Time-dependent alteration of endothelium-dependent relaxation in pulmonary micro-arteries by EC and UW solution --- p.19 / Chapter 2.2.4. --- Effect of HbO in endothelium-dependent relaxation --- p.19 / Chapter Chapter 3: --- Material and Methods --- p.21 / Chapter 3.1. --- General Methods --- p.21 / Chapter 3.1.1. --- Porcine heart and lung collection and transportion / Chapter 3.1.2. --- Myograph --- p.21 / Chapter 3.1.3. --- Myosight --- p.24 / Chapter 3.1.4. --- Anatomizing blood vessel --- p.24 / Chapter 3.1.5. --- Mounting --- p.24 / Chapter 3.1.6 --- Normalization --- p.26 / Chapter 3.1.6.1. --- Normalization of coronary micro-artery --- p.27 / Chapter 3.1.6.2. --- Normalization of pulmonary micro-artery --- p.28 / Chapter 3.1.7. --- Precontraction --- p.30 / Chapter 3.1.8. --- Endothelium-dependent relaxation --- p.31 / Chapter 3.2. --- Coronary artery studies --- p.32 / Chapter 3.2.1. --- Porcine heart harvest and anatomy --- p.32 / Chapter 3.2.2. --- Characteristic of histology of porcine coronary micro-artery --- p.32 / Chapter 3.3. --- Pulmonary artery studies --- p.35 / Chapter 3.3.1. --- Porcine lung harvest and anatomy --- p.35 / Chapter 3.3.2. --- Characteristic of histology of porcine pulmonary micro- artery --- p.36 / Chapter 3.4. --- Drugs --- p.41 / Chapter 3.4.1. --- Drugs --- p.41 / Chapter 3.4.2. --- Preparation of oxyhemoglobin solution --- p.41 / Chapter 3.5. --- Statistical Analysis --- p.42 / Chapter 3.5.1. --- Calculation of EC50 --- p.42 / Chapter 3.5.2. --- Statistical analysis --- p.42 / Chapter Chapter 4: --- "Epoxyeicosatrienoic Acids (EET11,12) May Partially Restore EDHF-Mediated Function in Coronary Micro-Arteries" --- p.43 / Chapter 4.1. --- Abstract --- p.43 / Chapter 4.2. --- Introduction --- p.44 / Chapter 4.3. --- Experimental Protocol --- p.45 / Chapter 4.3.1. --- Precontraction --- p.45 / Chapter 4.3.2. --- "EDHF-mediated (INDO, L-NNA, and HbO-resistant) relaxation" --- p.45 / Chapter 4.3.3. --- "EET11,12-mediated relaxation after exposure to hyperkalemia" --- p.46 / Chapter 4.3.4. --- "The effect of incubation with EET11,12 on the BK-induced, EDHF-mediated relaxation" --- p.46 / Chapter 4.4. --- Results --- p.47 / Chapter 4.4.1. --- Resting force --- p.47 / Chapter 4.4.2. --- HbO and U46619-induced contraction force --- p.48 / Chapter 4.4.3. --- "EET11,12-induced relaxation in coronary micro-arteries after exposure to hyperkalemia" --- p.49 / Chapter 4.4.4. --- "The EDHF-mediated relaxation to BK resistant to INDO, l- NNA,and HbO" --- p.51 / Chapter 4.4.4.1. --- Incubated in either hyperkalemic solution (K+ 20mmol/L) or Krebs' solution (control) --- p.51 / Chapter 4.4.4.2. --- "Incubated in either hyperkalemic solution (K+ 20mmol/L) plus EET11,12 or Krebs' solution (control)" --- p.53 / Chapter 4.5. --- Discussion --- p.57 / Chapter 4.5.1. --- EDHF plays an important role in the coronary micro-arteries --- p.57 / Chapter 4.5.2. --- "EDHF-mediated (INDO, l-NNA, and HbO-resistant) relaxation in the coronary micro-arteries" --- p.58 / Chapter 4.5.3. --- "EET11,12 may partially mimic the EDHF-mediated relaxation in the porcine coronary micro-artery" --- p.59 / Chapter 4.5.4. --- "Effect of EET11,12 added in hyperkalemia may partially restore the EDHF-mediated relaxation in the porcine coronary micro-arteries" --- p.59 / Chapter Chapter 5: --- Impaired EDHF-Mediated Relaxationin Porcine Pulmonary Micro-arteries by Cold Store with Euro-Collin's and University of Wisconsin Solution --- p.61 / Chapter 5.1. --- Abstract --- p.61 / Chapter 5.2. --- Introduction --- p.62 / Chapter 5.3. --- Experimental Protocol --- p.64 / Chapter 5.3.1. --- Precontraction --- p.64 / Chapter 5.3.2. --- "Role of EDHF-mediated (INDO, L-NNA and HbO-resistant) relaxation in porcine pulmonary micro-arteries by BK orA23187" --- p.64 / Chapter 5.3.3. --- Effect of hyperkalemia or preservation solutions (EC or UW) on the EDHF-mediated relaxation by BK or A23187 --- p.65 / Chapter 5.3.3.1. --- The effect of hyperkalemia --- p.65 / Chapter 5.3.3.2. --- Effect of EC solution on the EDHF-mediated relaxation --- p.65 / Chapter 5.3.3.3. --- Effect of UW solution on the EDHF-mediated relaxation --- p.66 / Chapter 5.3.3.4. --- The effect of UW and EC solutions on the contractility of the pulmonary micro-artery --- p.66 / Chapter 5.4. --- Results --- p.66 / Chapter 5.4.1. --- Resting force --- p.66 / Chapter 5.4.2. --- U46619-induced contraction force --- p.67 / Chapter 5.4.3. --- Role of EDHF-mediated relaxation induced by BK or A23187 --- p.67 / Chapter 5.4.4. --- The effect of hyperkalemia --- p.71 / Chapter 5.4.5. --- Effect of EC solution on the EDHF-mediated relaxation --- p.72 / Chapter 5.4.6. --- Effect of UW solution on the EDHF-mediated relaxation --- p.73 / Chapter 5.4.7. --- The effect of UW and EC solution on the contractility of the pulmonary micro-artery --- p.73 / Chapter 5.5. --- Discussion --- p.77 / Chapter 5.5.1. --- EDHF-mediated endothelial function exists in the pulmonary micro-circulation --- p.77 / Chapter 5.5.2. --- Hyperkalemia exposure reduces EDHF-related relaxation and possible mechanism --- p.78 / Chapter 5.5.3. --- The effect of EC and UW solutions on the EDHF-media relaxation in the pulmonary micro-arteries --- p.79 / Chapter Chapter 6: --- General Discussion --- p.82 / Chapter 6.1. --- Endothelium-dependent vasodilators: BK and A23187 --- p.82 / Chapter 6.2. --- EDHF in porcine coronary and pulmonary micro-arteries --- p.84 / Chapter 6.2.1. --- EDHF in porcine coronary micro-arteries --- p.84 / Chapter 6.2.2. --- EDHF in porcine pulmonary micro-arteries --- p.87 / Chapter 6.2.3. --- Vascular stretch and release of endothelium-derived vasodilators --- p.87 / Chapter 6.2.4. --- "EET11,12" --- p.88 / Chapter 6.3. --- "Endothelium-dependent relaxation resistant to INDO, L- NNA, and HbO in porcine coronary and pulmonary microcirculation" --- p.89 / Chapter 6.4. --- "Alteration of endothelium-dependent relaxation resistant to INDO, l-NNA, and HbO after exposure to hyperkalemia" --- p.90 / Chapter 6.5. --- "Alteration of endothelium-dependent contraction resistant to INDO, L-NNA, and HbO after exposure to EC or UW solutions" --- p.91 / Chapter 6.6. --- Clinical implications --- p.92 / Chapter 6.7. --- Limitations --- p.93 / Chapter 6.7.1. --- Common limitations --- p.93 / Chapter 6.7.2. --- Limitation of in vitro study --- p.93 / Chapter 6.8. --- Future work --- p.94 / Chapter Chapter 7: --- Conclusion --- p.96 / References --- p.98 / Appendies / "Wei Zou, Qin Yang, Anthony PC Yim, & Guo-Wei He Epoxyeicosatrienoic acids (EET11,12) may partially restore endothelium- derived hyperpolarizing factor-mediated function in coronary micro- arteries. Annals of Thoracic Surgery. 2001; 72(12): 1970~1976."

Introdução: A hipertensão arterial pulmonar (HAP) é uma doença grave da circulação pulmonar, cujo diagnóstico e cuja avaliação funcional dependem do cateterismo cardíaco direito. A tomografia de dupla energia (TCDE), por meio da técnica de decomposição de materiais, permite obter um mapa de Iodo do parênquima pulmonar, que pode ser avaliado de forma qualitativa e quantitativa, e pode ser útil na avaliação da HAP. Objetivos: Avaliar a distribuição de Iodo no parênquima pulmonar, comparando com marcadores hemodinâmicos, marcadores de gravidade e com grupo-controle normopressórico. Métodos: Pacientes com HAP, acompanhados na Unidade de Circulação Pulmonar (InCor-HCFMUSP), foram avaliados por angiotomografia das artérias pulmonares (angioTC) como parte de sua rotina diagnóstica, em modo de dupla energia. O grupo-controle foi composto por pacientes com suspeita clínica de tromboembolismo pulmonar (TEP), com angioTC negativa para TEP e com ecocardiograma normal. Foram avaliadas as concentrações de Iodo no pulmão (mg/mL) por meio de 8 regiões de interesse redondas com 1 cm2 de área, distribuídas ao longo do eixo ântero-posterior do pulmão direito, em 3 níveis predeterminados. Foram obtidas, também, as medidas do ventrículo direito (VD), ventrículo esquerdo (VE), razão VD/VE, diâmetros da aorta (AO) e artéria pulmonar (AP). O realce da artéria pulmonar por meio da TCDE (PAenh) também foi obtido. Os resultados foram comparados entre os grupos, e correlacionados no grupo HAP com parâmetros hemodinâmicos invasivos e marcadores de gravidade. Resultados: O grupo HAP foi composto por 21 pacientes, com idade média de 42 anos, 47,6% em classe funcional I/II. Houve diferença significativa nos diâmetros da AP (p<0,01), VD (p<0,01), e VE (p=0,01), entre os grupos HAP e controle. Também demonstraram diferenças significativas às relações entre os diâmetros AP/AO (p < 0,01) e VD/VE (p < 0,01), entre os grupos. Calibre da artéria pulmonar maior do que 2,9 cm e relação AP/AO maior do que 1,1 cm demonstraram sensibilidade de 90,5% e 87,5%, e especificidade de 100% para o diagnóstico de HP. A PAenh não demonstrou diferenças significativas entre os grupos HAP e controle, contudo se correlacionou significativamente com a medida do débito cardíaco no grupo HAP (r=-0,661, p=0,01). A PAPm demonstrou correlação com a relação AP/AO (r=0,676) e, também, com a relação VD/VE (r=0,679), ambas com p < 0,01. A concentração de Iodo no parênquima foi significativamente menor no grupo HAP em todos os segmentos analisados. O mapa de Iodo demonstrou gradiente progressivo da concentração de Iodo no parênquima pulmonar, de caráter ântero-posterior, em ambos os grupos, de magnitude significativamente menor no grupo HAP. Usando-se o valor de PAenh para correção das medidas de concentração de Iodo, deixa de haver diferença entre os grupos HAP e controle. Conclusões: A TCDE, além das medidas anatômicas obtidas pela técnica convencional, permitiu demonstrar a manutenção do gradiente ântero-posterior da concentração de Iodo em pacientes com HAP, sugerindo que sua menor magnitude seja determinada pelo baixo débito cardíaco / Background: Pulmonary arterial hypertension (PAH) is a severe disease of the pulmonary circulation. Right heart catheterization (RHC) is crucial for diagnosis and management of these patients. High-resolution computed tomography (CT) and CT angiography play a crucial role in the diagnostic work-up of pulmonary hypertension. Dual energy computed tomography (DECT) is a technique of acquisition of modern CT scanners that allows obtaining a computed tomography of the pulmonary arteries with low iodine dose, and providing an estimation of iodine distribution in the lungs. Although the search for non-invasive methods for evaluation of PAH is developing, data concerning application of DECT on PAH patients remain scarce. Objectives: To evaluate the iodine distribution in the lungs obtained by DECT in PAH patients and a control group and compare to the hemodynamic profile, and prognostic markers of PAH patients. Methods: 21 patients followed at the Pulmonary Circulation Unit (InCor-HCFMUSP) and submitted to CT angiography were evaluated by DECT. A matched control group was composed by patients routinely referred to CT angiography to rule out pulmonary embolism with negative results and also a normal echocardiogram obtained at the same day. Eight circular 1cm2 ROIs were placed along the anteroposterior axis, at the middle of the right lung and at predetermined levels to measure the Iodine concentration in the lungs. Measurements of the pulmonary artery (PA), ascending aorta (AO), right ventricle (RV) and left ventricles (LV) were obtained, as well as enhancement of the PA (PAenh). Results were compared to the control group, and correlated with hemodynamic parameters in the PAH group. Results: PAH patients averaged 42 y/o, female/male ratio of 7/1, NYA functional classes I/II. Statistically significant differences between PAH patients and controls were found regarding measurements of PA (p < 0,01), RV (p < 0,01), LV (p=0,01), PA/AO (p < 0,01) and RV/LV (p < 0,01). PA diameter greater than 2,9 cm and PA/AO ratio greater 1,1 were diagnostic for pulmonary hypertension with sensitivity/specifity of 90,5%/100% and 87,5%/100%. PAenh showed no statistical difference between PAH patients and controls . A characteristic anteroposterior Iodine concentration gradient was found in all subjects, both PAH patients showed lower Iodine concentration diffusely (p < 0,01). When corrected by PAenh, Iodine gradients showed no statistical difference between PAH patients and controls. PAenh correlates with cardiac output (r=-0,661), and mPaP correlates with PA/AO ratio (r=0,676), RV/LV ratio VD/VE ratio (r=0,679), and p<0,01. Conclusion: Anteroposterior Iodine concentration gradient is preserved in PAH in comparison with controls, but with lower magnitude. This difference was corrected through the multiplication of individual Iodine measurements by PAenh, suggesting that this could be explained by lower blood flow to the lungs of PAH patients. PAenh correlates with cardiac output, mean pulmonary arterial pressure correlates with PA/AO and RV/LV in PAH patients. DECT provided conventional anatomic measurements and allowed the characterization of preserved anteroposterior Iodine gradients in PAH patients, with decreased magnitude in comparison with controls, that could be atributed to a lower CO of these patients

Introdução: A hipertensão arterial pulmonar (HAP) é uma doença grave da circulação pulmonar, cujo diagnóstico e cuja avaliação funcional dependem do cateterismo cardíaco direito. A tomografia de dupla energia (TCDE), por meio da técnica de decomposição de materiais, permite obter um mapa de Iodo do parênquima pulmonar, que pode ser avaliado de forma qualitativa e quantitativa, e pode ser útil na avaliação da HAP. Objetivos: Avaliar a distribuição de Iodo no parênquima pulmonar, comparando com marcadores hemodinâmicos, marcadores de gravidade e com grupo-controle normopressórico. Métodos: Pacientes com HAP, acompanhados na Unidade de Circulação Pulmonar (InCor-HCFMUSP), foram avaliados por angiotomografia das artérias pulmonares (angioTC) como parte de sua rotina diagnóstica, em modo de dupla energia. O grupo-controle foi composto por pacientes com suspeita clínica de tromboembolismo pulmonar (TEP), com angioTC negativa para TEP e com ecocardiograma normal. Foram avaliadas as concentrações de Iodo no pulmão (mg/mL) por meio de 8 regiões de interesse redondas com 1 cm2 de área, distribuídas ao longo do eixo ântero-posterior do pulmão direito, em 3 níveis predeterminados. Foram obtidas, também, as medidas do ventrículo direito (VD), ventrículo esquerdo (VE), razão VD/VE, diâmetros da aorta (AO) e artéria pulmonar (AP). O realce da artéria pulmonar por meio da TCDE (PAenh) também foi obtido. Os resultados foram comparados entre os grupos, e correlacionados no grupo HAP com parâmetros hemodinâmicos invasivos e marcadores de gravidade. Resultados: O grupo HAP foi composto por 21 pacientes, com idade média de 42 anos, 47,6% em classe funcional I/II. Houve diferença significativa nos diâmetros da AP (p<0,01), VD (p<0,01), e VE (p=0,01), entre os grupos HAP e controle. Também demonstraram diferenças significativas às relações entre os diâmetros AP/AO (p < 0,01) e VD/VE (p < 0,01), entre os grupos. Calibre da artéria pulmonar maior do que 2,9 cm e relação AP/AO maior do que 1,1 cm demonstraram sensibilidade de 90,5% e 87,5%, e especificidade de 100% para o diagnóstico de HP. A PAenh não demonstrou diferenças significativas entre os grupos HAP e controle, contudo se correlacionou significativamente com a medida do débito cardíaco no grupo HAP (r=-0,661, p=0,01). A PAPm demonstrou correlação com a relação AP/AO (r=0,676) e, também, com a relação VD/VE (r=0,679), ambas com p < 0,01. A concentração de Iodo no parênquima foi significativamente menor no grupo HAP em todos os segmentos analisados. O mapa de Iodo demonstrou gradiente progressivo da concentração de Iodo no parênquima pulmonar, de caráter ântero-posterior, em ambos os grupos, de magnitude significativamente menor no grupo HAP. Usando-se o valor de PAenh para correção das medidas de concentração de Iodo, deixa de haver diferença entre os grupos HAP e controle. Conclusões: A TCDE, além das medidas anatômicas obtidas pela técnica convencional, permitiu demonstrar a manutenção do gradiente ântero-posterior da concentração de Iodo em pacientes com HAP, sugerindo que sua menor magnitude seja determinada pelo baixo débito cardíaco / Background: Pulmonary arterial hypertension (PAH) is a severe disease of the pulmonary circulation. Right heart catheterization (RHC) is crucial for diagnosis and management of these patients. High-resolution computed tomography (CT) and CT angiography play a crucial role in the diagnostic work-up of pulmonary hypertension. Dual energy computed tomography (DECT) is a technique of acquisition of modern CT scanners that allows obtaining a computed tomography of the pulmonary arteries with low iodine dose, and providing an estimation of iodine distribution in the lungs. Although the search for non-invasive methods for evaluation of PAH is developing, data concerning application of DECT on PAH patients remain scarce. Objectives: To evaluate the iodine distribution in the lungs obtained by DECT in PAH patients and a control group and compare to the hemodynamic profile, and prognostic markers of PAH patients. Methods: 21 patients followed at the Pulmonary Circulation Unit (InCor-HCFMUSP) and submitted to CT angiography were evaluated by DECT. A matched control group was composed by patients routinely referred to CT angiography to rule out pulmonary embolism with negative results and also a normal echocardiogram obtained at the same day. Eight circular 1cm2 ROIs were placed along the anteroposterior axis, at the middle of the right lung and at predetermined levels to measure the Iodine concentration in the lungs. Measurements of the pulmonary artery (PA), ascending aorta (AO), right ventricle (RV) and left ventricles (LV) were obtained, as well as enhancement of the PA (PAenh). Results were compared to the control group, and correlated with hemodynamic parameters in the PAH group. Results: PAH patients averaged 42 y/o, female/male ratio of 7/1, NYA functional classes I/II. Statistically significant differences between PAH patients and controls were found regarding measurements of PA (p < 0,01), RV (p < 0,01), LV (p=0,01), PA/AO (p < 0,01) and RV/LV (p < 0,01). PA diameter greater than 2,9 cm and PA/AO ratio greater 1,1 were diagnostic for pulmonary hypertension with sensitivity/specifity of 90,5%/100% and 87,5%/100%. PAenh showed no statistical difference between PAH patients and controls . A characteristic anteroposterior Iodine concentration gradient was found in all subjects, both PAH patients showed lower Iodine concentration diffusely (p < 0,01). When corrected by PAenh, Iodine gradients showed no statistical difference between PAH patients and controls. PAenh correlates with cardiac output (r=-0,661), and mPaP correlates with PA/AO ratio (r=0,676), RV/LV ratio VD/VE ratio (r=0,679), and p<0,01. Conclusion: Anteroposterior Iodine concentration gradient is preserved in PAH in comparison with controls, but with lower magnitude. This difference was corrected through the multiplication of individual Iodine measurements by PAenh, suggesting that this could be explained by lower blood flow to the lungs of PAH patients. PAenh correlates with cardiac output, mean pulmonary arterial pressure correlates with PA/AO and RV/LV in PAH patients. DECT provided conventional anatomic measurements and allowed the characterization of preserved anteroposterior Iodine gradients in PAH patients, with decreased magnitude in comparison with controls, that could be atributed to a lower CO of these patients

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 4 uppsatser.

La dysplasie broncho-pulmonaire (DBP), complication fréquente de la prématurité, atteint 30% des nouveau-nés de faible poids de naissance. L’hypertension artérielle pulmonaire persistante du nouveau-né (HTAPP), associé ou non à la DBP, résulte d’une mauvaise adaptation à la vie extra-utérine et survient dans diverses situations pathologiques (prématurité, sepsis, inhalation de méconium, hernie diaphragmatique congénitale…). Ces 2 pathologies sont grevées d’une morbidité et d’une mortalité importante en période périnatale. En effet, certaines situations d’HTAPP ou de DBP sévères restent réfractaires aux thérapeutiques actuelles.Les acides gras polyinsaturés oméga 3 (AGPI ω-3) sont des nutriments aux propriétés bénéfiques sur le système circulatoire et pulmonaire, mais également sur le développement fœtal, démontrés par de nombreuses études expérimentales et cliniques. La déhydroépiandrostérone (DHEA) est une hormone stéroïdienne dont le taux de sécrétion chez l’homme diminue avec l’âge. Des études récentes ont démontré un effet cardio-protecteur mais également un effet vasodilatateur pulmonaire et préventif de lésions de DBP dans des modèles expérimentaux.Les buts de notre travail étaient 1) d’étudier l’effet d’une supplémentation en AGPI ω-3 dans un modèle expérimental de DBP induite par hyperoxie chez le raton, 2) d’étudier l’effet circulatoire d’injection d’AGPI ω-3 (in vivo) dans un modèle d’étude de la circulation pulmonaire chez le fœtus de brebis chroniquement instrumenté, et d’étudier les mécanismes d’action AGPI ω-3 (anneaux vasculaires isolés) , enfin 3) d’étudier l’effet circulatoire de la DHEA (in vivo) dans le modèle de fœtus de brebis et d’étudier les mécanismes d’actions de la DHEA sur la circulation pulmonaire fœtale (in vivo)._x000D_Nous avons démontré que la supplémentation par voie orale en AGPI ω-3 de rates gestantes à la fin de la gestation et après la naissance permettait de prévenir, chez les ratons nouveau-nés, les lésions de DBP induites par une exposition chronique à l’hyperoxie. Ces lésions étaient retrouvées dans les groupes contrôles (eau et AGPI ω-6). Cette étude n’avait pas retrouvée d’effet bénéfique des AGPI ω-3 sur le remodelage vasculaire induit.L’injection d’acide eicosapentaènoique (EPA) chez le fœtus de brebis a révélé un effet vasodilatateur pulmonaire puissant avec une baisse significative et prolongée des résistances vasculaires pulmonaires (RVP), en comparaison à l’injection d’acide docosahéxaènoique (DHA) ou de l’excipient (faible dose d’éthanol). L’effet vasorelaxant de l’EPA sur des anneaux isolés pré-contractés était plus important que celui du DHA à dose équivalente, et il était dose- et endothélium-dépendent. Enfin, cet effet impliquait la voie de production du NO puisqu’il était diminué lors du traitement des anneaux par le L-Nitro-Arginine (LNA), inhibant la NO synthase.L’étude de perfusion en bolus de DHEA dans le lit pulmonaire vasculaire chez le fœtus de brebis instrumenté mettait en évidence un effet vasodilatateur bref. Cet effet était dose-dépendant avec une baisse plus prononcée des RVP et une durée plus importante pour des doses de DHEA plus importantes. Enfin l’étude des mécanismes d’action retrouvait une inhibition de l’effet de la DHEA par le LNA, démontrant une action vasodilatatrice par activation de production du NO.L’ensemble de ces travaux permet de suggérer que les AGPI ω-3 représentent des nutriments intéressants en période périnatale (grossesse, allaitement et per os), notamment en traitement préventif dans les situations à risque de DBP, ou curatif en cas d’HTAPP. La DHEA reste une piste dans le traitement de l’HTAP, mais semble pour l’instant plus difficile à instaurer en clinique humaine. / Bronchopulmonary dysplasia (BPD), a common complication of prematurity, reached in 30% of newborns with very low birth weight. Persistent pulmonary hypertension of the newborn (PPHN), with or without BPD, results in poor adaptation to extrauterine life and occurs in various pathological conditions such as prematurity, sepsis, inhaled meconium, or diaphragmatic hernia Congenital. The mortality and morbidities of these two diseases are high in the perinatal period. Severe PPHN or BPD are refractory to current treatment.Polyunsaturated fatty acids omega-3 (ω-3 PUFA) are nutrients with beneficial properties on the circulatory and pulmonary system, but also on fetal development, demonstrated by many experimental and clinical studies. Dehydroepiandrosterone (DHEA) is a steroid hormone whose secretion levels in humans decreases with age. Recent studies have demonstrated a cardio-protective effect of diet DHEA supplementation but also a pulmonary vasodilator and preventive effect of DBP injury in experimental models.The aims of our study were : 1) to study the effect of PUFA ω-3 supplementation in an experimental model of hyperoxia-induced DBP in pups; 2) to study effect on pulmonary circulation of infusion of ω-3 PUFAs (in vivo) in model of chronically instrumented fetal sheep, and to analyze the mechanisms of action of ω-3 PUFA (isolated vascular rings); and finally 3) to study the in vivo effect of DHEA in fetal pulmonary circulation in the same model of fetal sheep and to understand the mechanisms of action of DHEA._x000D_We have demonstrated that supplementation with diet PUFA ω-3 on pregnant rats at the end of gestation and after birth prevent BPD injuries induced by chronic exposure to hyperoxia in pups. These lesions were found in the control groups (water and ω-6 PUFA). ω-3 PUFA supplementation did not prevent vascular remodeling.Infusion of eicosapentaenoic acid (EPA) in sheep fetus showed a potent pulmonary vasodilator effect as compared to docosahexaenoic acid (DHA) or excipient (low dose of ethanol). Vasorelaxant effect of EPA on pre-contracted isolated rings was more important than DHA at equivalent dose, and was dose- and endothelium-dependent. This effect involves NO production.Bolus DHEA perfusion in the pulmonary vascular bed study on instrumented fetal sheep highlighted an acute vasodilator effect. This effect was dose-dependent with a more pronounced and sustained decrease in PVR at highest doses of DHEA. Finally, mechanisms of action study found an inhibition of the effect of DHEA by the LNA, indicating that DHEA-induced vasodilation is NO dependant.Taken together, our results suggest that supplementation with ω-3 PUFAs and DHEA within the perinatal period may prevent BPD and PPHN in high risk conditions including preterm birth, premature rupture of the membrane or intrauterine growth restriction.

Background: Inhaled carbon monoxide (CO) appears to have beneficial effects on endotoxemia-induced impairment of hypoxic pulmonary vasoconstriction (HPV). This study aims to specify correct timing of CO application, it’s biochemical mechanisms and effects on inflammatory reactions. Methods: Mice (C57BL/6; n = 86) received lipopolysaccharide (LPS, 30 mg/kg) intraperitoneally and subsequently breathed 50 ppm CO continuously during defined intervals of 3, 6, 12 or 18 h. Two control groups received saline intraperitoneally and additionally either air or CO, and one control group received LPS but breathed air only. In an isolated lung perfusion model vasoconstrictor response to hypoxia (FiO2 = 0.01) was quantified by measurements of pulmonary artery pressure. Pulmonary capillary pressure was estimated by double occlusion technique. Further, inflammatory plasma cytokines and lung tissue mRNA of nitric-oxide-synthase-2 (NOS-2) and heme oxygenase-1 (HO-1) were measured. Results: HPV was impaired after LPS-challenge (p < 0.01). CO exposure restored HPV-responsiveness if administered continuously for full 18 h, for the first 6 h and if given in the interval between the 3rd and 6th hour after LPS-challenge (p < 0.05). Preserved HPV was attributable to recovered arterial resistance and associated with significant reduction in NOS-2 mRNA when compared to controls (p < 0.05). We found no effects on inflammatory plasma cytokines. Conclusion: Low-dose CO prevented LPS-induced impairment of HPV in a time-dependent manner, associated with a decreased NOS-2 expression.

A lesão pulmonar é a principal causa de morte da Esclerose Sistêmica (ES), e as alterações principais são: o acometimento intersticial e o vascular. No presente estudo analisamos através do microscópio confocal a laser 40 artérias pulmonares de pequeno e médio calibre de pacientes com ES e 16 controles. Medimos a área do lúmen, a área total do vaso e fizemos a subtração da área total do vaso menos a do lúmen, e a porcentagem da área do lúmen em relação à área total do vaso. Observou-se que a área do lúmen e a porcentagem da área do lúmen em relação a área total do vaso são significativamente menores na ES em relação ao controle, e que a diferença entre a área total do vaso e a área do lúmen foi maior no grupo ES. Os achados confirmaram a hipótese inicial de acometimento das artérias pulmonares na ES, que se encontram espessadas devido à inflamação, infiltração celular em suas camadas e ativação endotelial / Lung injury is the leading cause of death in Systemic Sclerosis (SSc), and the main changes are: the vascular and interstitial involvement. In this study we analyzed through the confocal laser microscope 40 lung arteries of small and medium-sized of patients with SSc and 16 arteries of control group. We measured the lumen area, the total vessel area, made the subtracting the total vessel area minus the lumen area and the percentage between the lumen area and total vessel area. It was observed that the lumen area and the percentage between the lumen area and total vessel area were significantly lower in SSc group compared to control group, and the difference between the total vessel and the lumen area was higher in SSc. The findings confirmed the initial hypothesis of pulmonary arterial injury in SSc, wich are thickened due to inflammation, cellular infiltration into its layers and endothelial activation