Dissertations / Theses on the topic 'Lung'

The generation of oxygen free radicals by the cytosolic enzyme, xanthine oxidase (XO), has been implicated in post-ischemic or reperfusion damage in several organs. XO catalyzes the conversion of hypoxanthine to urate with the concomitant production of superoxide anion free radical (0₂̅˙) and hydrogen peroxide (H₂O₂). Oxygen free radical-mediated injury has also been demonstrated in inflammatory lung disease. The possible involvement of XO in oxidative injury in the lung has not yet been studied. Therefore, this research project was designed to determine whether XO is present in the lung and to investigate its characteristics in porcine, bovine, rat and human lung and other tissues. Immunochemical analysis of xanthine oxidase in the tissues employed on polyclonal antibody raised to bovine milk XO. Proteins were separated by SDS-polyacrylamide gel electrophoresis of tissue homogenates. Proteins were transfered from the gels to nitrocellulose filters by Western blotting. After incubating the filters with a antisera containing the antibody to the purified bovine XO. XO on the filter was detected by its reaction with an enzyme-conjugated second antibody. XO was immunologically detectable in bovine lung and milk. Rat lung, kidney and liver all showed XO reactivity. XO was detectable in porcine liver but not detectable in porcine lung or kidney. Thus, the antibody to bovine XO was cross-reactive with porcine and rat XO. XO protein was not immunologically detectable in human lung possibly because the antibody was not cross reactive with the bovine antibody. In vivo, xanthine oxidase exists predominantly as a dehydrogenase rather than an oxidase. In this form as xanthine dehydrogenase (XDH) the enxyme does not produce either 0₂̅˙ or H₂O₂. The activity of both XDH and XO was measured in several tissues using a fluorometric assay which uses an artifical substrate, pterin which is catalytically converted to the fluorescent product isoxanthopterin (IXP). XO activity in porcine liver was of 1.1 x 10⁻³ µg IXP/mg protein/min although XO activity was not detectable in porcine lung and kidney, in rat lung of 1.7 x 10⁻² µg IXP/mg protein/min, rat kidney of 1.5 x 10⁻² µg IXP/mg protein/min, and rat liver of 2.2 x 10⁻² µg IXP/mg protein/min. Seven human lung biopsy samples were obtained after lung resection and initially tested for viability by determination of NADH oxidase activity and then assayed for XO-XDH. Three of these samples showed NADH oxidase activity indicating tissue viability, but only one of these three showed measurable XO activity of 5.35 x 10⁻⁶ µg IXP/mg protein/min. Irreversible conversion of XDH to XO is thought to be the result of limited proteolysis by a Ca²⁺/calmodulin activated protease, whereas reversible conversion of the enzyme occurs by oxidation of critical thiol groups. Studies on the rate and nature of fluorescence assay to detect catalytic activities of both enzyme forms. Incubation of lung homogenates with trypsin for 60 min caused irreverisble conversion of 90% of the XDH to XO. In contrast, incubation of homogenates at 15°C for 10 hours caused conversion of 100% of the XDH to XO. This conversion was reversible to the extent of 80% by reduction of thiol groups with dithiothreitol (DTT). The effects of free Ca²⁺ on the conversion of XDH to X0 was examined by using EDTA, a chelator of Ca²⁺ and other divalent cations; and EGTA, a more specific chelator of Ca²⁺. The presence of these chelating agents during homogenization of either normoxic or ischemic rat lung tissue did not inhibit reversible enzyme conversion. Increased XO activity was reversible by DTT. In the normoxic rat lung, homogenates prepared with EDTA and EGTA showed a similar conversion of 95% of XDH to XO which was reversible to 70% with DTT. In the ischemic rat lung, samples prepared with EDTA and EGTA showed a'conversion of 80% and 95% XDH to XO which was similar to control samples. The extent of reversibility to XDH was 75% with DTT incubation. In addition, perfusion of rat lungs with EDTA and DTT via a pulmonary artery cannula prior to 60 min of ischemia and homogenization did not affect the extent of XDH to XO conversion. These results indicate that irreversible Ca²⁺-mediated proteolytic conversion of XDH to XO does not occur to a great extent in the rat lung during either normoxia or ischemia. However, reversible conversion of XDH to XO does occur, suggesting that reversible thiol dependent conversion may play a role in the lung under both physiological and pathophysiological states.
Medicine, Faculty of
Pathology and Laboratory Medicine, Department of
Graduate

Background: Atelectasis can provoke pulmonary and non-pulmonary complications after general anaesthesia. Unfortunately, there is no instrument to estimate atelectasis and prompt changes of mechanical ventilation during general anaesthesia. Although arterial partial pressure of oxygen (PaO2) and intrapulmonary shunt have both been suggested to correlate with atelectasis, studies yielded inconsistent results. Therefore, we investigated these correlations. Methods: Shunt, PaO2 and atelectasis were measured in 11 sheep and 23 pigs with otherwise normal lungs. In pigs, contrasting measurements were available 12 hours after induction of acute respiratory distress syndrome (ARDS). Atelectasis was calculated by computed tomography relative to total lung mass (Mtotal). We logarithmically transformed PaO2 (lnPaO2) to linearize its relationships with shunt and atelectasis. Data are given as median (interquartile range). Results: Mtotal was 768 (715–884) g in sheep and 543 (503–583) g in pigs. Atelectasis was 26 (16–47)% in sheep and 18 (13–23) % in pigs. PaO2 (FiO2 = 1.0) was 242 (106–414) mmHg in sheep and 480 (437–514) mmHg in pigs. Shunt was 39 (29–51)% in sheep and 15 (11–20) % in pigs. Atelectasis correlated closely with lnPaO2 (R2 = 0.78) and shunt (R2 = 0.79) in sheep (P-values<0.0001). The correlation of atelectasis with lnPaO2 (R2 = 0.63) and shunt (R2 = 0.34) was weaker in pigs, but R2 increased to 0.71 for lnPaO2 and 0.72 for shunt 12 hours after induction of ARDS. In both, sheep and pigs, changes in atelectasis correlated strongly with corresponding changes in lnPaO2 and shunt. Discussion and Conclusion: In lung-healthy sheep, atelectasis correlates closely with lnPaO2 and shunt, when blood gases are measured during ventilation with pure oxygen. In lung-healthy pigs, these correlations were significantly weaker, likely because pigs have stronger hypoxic pulmonary vasoconstriction (HPV) than sheep and humans. Nevertheless, correlations improved also in pigs after blunting of HPV during ARDS. In humans, the observed relationships may aid in assessing anaesthesia-related atelectasis.

Infants with bronchopulmonary dysplasia (BPD), showed impaired body growth when compared to control infants. In terms of changes in the biochemical composition of the lung, BPD infants had higher DNA, soluble protein, collagen and desmosine contents as well as increased concentrations of DNA, collagen and desmosine in their lungs when compared to the growth patterns obtained for the lungs of control infants. Pathologically BPD was classified into 4 grades. Grade I BPD, was a phase of acute lung injury, grades II and III were proliferative phases. In grade IV BPD, lung structure returned towards normal. Evidence of fibrosis was seen by a significant increase in collagen concentration in grades II and III while desmosine concentration was seen to increase in grades III and IV suggesting that the increase in collagen and desmosine contents in the lungs of BPD infants may be controlled by two different mechanisms. Collagen type I/III ratio was seen to decrease progressively from grade II to grade IV BPD in comparison to age matched controls, indicating a higher proportion of type III collagen in the lungs of infants with BPD. From the clinical analysis and the results obtained from discriminant analysis procedure, it was seen that there was a high degree of correlation between the continuation of the disease and collagen accumulation in the lungs suggesting that pulmonary fibrosis with excessive collagen accumulation is an integral part of BPD. This fibrotic process seemed to correlate significantly with assisted ventilation and high oxygen supplementation received by the infants, but it was difficult to assess the individual contribution of the two treatments in the pathogenesis of BPD. Other variables such as severity of the initial disease and the length of survival of the infants, made the assessment of individual contribution much more difficult.
Medicine, Faculty of
Pathology and Laboratory Medicine, Department of
Graduate

The aim of this thesis is a data transfer protocol implementation for a mobile control unit for transporting lungs. Apart from this thesis the data transfer protocol is used in AlveoPic project. The introductory part is focused on an anatomical and physiological background of a human respiratory system. Consequently it describes the i-Lung module and the mobile circulation module (MCM). It deals with the healthcare informatics interoperability standards with an emphasis to the ISO/IEEE 11073 standard. The subsequent part is represented by MCM’s simulator realization and design of a monitoring application. The final part aims at an analysis of the test cases for a monitoring application’s and a protocol framework’s control.

Introduction: CF (cystic fibrosis) and PCD (primary ciliary dyskinesia) are obstructive airway diseases characterised by frequent infections and neutrophilic inflammation. However, PCD has a much milder course than CF. Pilot data showed that in PCD (n=8) the relationship between LCI (lung clearance index) derived from multiple breath washout (MBW), and FEV1 (forced expiratory volume in 1 second) differed from the established correlation in CF. This thesis sought to identify the reasons. Materials and Methods: Larger PCD (n=38) and CF cohorts (n=125), a non-CF bronchiectasis comparator group (n=28), and healthy controls (n=44) were recruited. All performed LCI and spirometry, and subgroups had more complex MBW parameters (conventional and modified phase III analysis and curvilinearity) calculated and HRCT scans scored. Results: As in the pilot data, there was no relationship between LCI and FEV1 in PCD, unlike in CF. PCD patients had fewer structural abnormalities than CF despite similar or worse spirometry and LCI, and the relationship between HRCT and spirometry or LCI in PCD was again different from that seen in CF. MBW analyses showed that Scond* is near-normal in PCD, suggesting less flow asynchrony, compared with CF. Conclusions: There are differences in the nature of distal airway disease between PCD and CF. As the non-CF bronchiectasis patients were similar to CF (rather than PCD), this likely results from the primary mucociliary clearance defect in PCD compared with secondary impairment in the other two conditions. This may be important as care of PCD patients is extrapolated from that of CF patients, which may not be appropriate. It is important not to extrapolate outcome measures uncritically between different disease groups, both clinically and when planning randomised controlled trials. Finally, a better understanding of what causes the better prognosis in PCD may help identify future new treatment avenues in CF.

Lung transplant is the only available therapy for patients with advanced lung disease. The goal of this study was to examine the prevalence, origin, management and outcome of lung cancer in recipients of lung transplant at the Brigham and Women’s Hospital. We conducted a retrospective chart review of all lung transplantations in our institution from January 1990 until June 2012. The prevalence of lung cancer in the explanted lung was 6 (1.2%) of 462 and all cases were in subjects with lung fibrosis. All 4 subjects with lymph node involvement died of causes related to the malignancy. Nine (1.9%) of 462 patients were found to have bronchogenic carcinoma after lung transplant. The median time to diagnosis after lung transplant was 28 months with a range from 9 months to 10 years. Median survival was 8 months, with tumors involving lymph nodes or distant metastases associated with a markedly worse prognosis (median survival 7 months) than stage I disease (median survival 27 months). While stage I disease is associated with improved survival in this cohort, survival is still not comparable to that of the general population, likely influenced by the need for aggressive immune suppression.

The goal of this honors thesis is to facilitate in the general public, an understanding of respiratory physiology and the effects of cigarette smoke on respiratory system function. To accomplish this task I created an art installation comprising acrylic paintings on canvas and physiologic forms modelled in clay. After researching the current literature on tobacco smoke and respiratory system function I created these nine art pieces over the course of 16 weeks culminating in a two week (May 4th – May 18th 2015) public health art exhibit in the Kachina Lounge, Student Union, at The University of Arizona. Three acrylic paintings introduced the audience to the respiratory system, stages of lung cancer and the cycle of nicotine addiction. Six accompanying clay sculptures served to illustrate the changes that occur in cilia, alveoli, and bronchioles with Chronic Obstructive Pulmonary Disease.

Until recently it was assumed that the healthy mammalian lung did not harbour a microbiota, unlike other body sites. However, through the use of sequencing based technologies this has been shown to not be the case. Low biomass communities of microbes can be identified in the healthy lung and the lung microbiota in various diseases states has been shown to differ form these 'healthy' communities. The sheep respiratory microbiota is of interest from both an animal health perspective and due to the potential use of the sheep as a large animal model for studying the lung microbiota. In this thesis I seek to characterise the composition and variability of the sheep lung microbiota; the differences between the sheep upper and lower respiratory tract bacterial communities and to assess whether exhaled breath condensate collection can be used as a non-invasive lung microbiota sampling method. To study the bacterial communities present in samples I have used 16S rRNA gene sequencing and analysis. In Chapter 3 I examine the inter-individual and spatial variability present within the sheep lung microbiota. Protected specimen brushings were collected from three lung segments in six animals at three time-points. In a separate sheep a greater number of brushings was taken (n=16) in order to examine the amount of variability over a smaller spatial scale. I find that there can be large differences between the bacterial communities isolated from different locations within the lung, even over short distances. Samples also cluster by the sheep from which they were taken, indicating a host specific influence on the lung microbiota. In Chapter 4 I compare whole lung washes and oropharyngeal swabs from 40 lambs in order to examine the differences between the upper and lower respiratory tract microbiotas. I find that oropharyngeal swabs separate into rumen-like or upper respiratory tract-like bacterial communities. Despite the fact that in humans the upper and lower respiratory microbiotas have been shown to have similar compositions, the sheep lung microbiota samples in this study do not resemble either oropharyngeal samples or reagent only controls. In my first two results chapters, lung sampling methods were used which involved either anaesthesia combined with a bronchoscopic procedure (Chapter 3) or samples being taken from dead animals (Chapter 4). In Chapter 5 I assess whether there is a less invasive way of taking lung microbiota samples from a living individual, both to minimise the procedural stress on animals used as models and to increase the pool of potential volunteers for human lung microbiota studies. I compared samples taken via protected specimen brushings to samples taken via exhaled breath condensate collection, a less invasive sampling technique. I find that condensate samples contain less bacterial DNA and different bacteria than brushing samples, indicating that it is unlikely they could be used as a replacement for invasive sampling methods. In my final results chapter I compare the results across Chapters 3, 4 and 5 to identify bacteria which occur consistently in the sheep lung and could therefore potentially be described as core lung microbiota members. In conclusion, while I have found that there are large differences between the sheep lung microbiota and that which has previously been described in humans, the sheep can still be of use as a model in studies where these differences would not have a significant impact, such as in Chapter 5 of this thesis. I have identified several bacterial members of the core sheep lung microbiota which in future it would be interesting to better characterise and to assess whether they play a role in sheep health.

Die Morphologie der Buchlungen von Arachniden (Arachnida Lamarck, 1801 – Arthropoda, Chelicerata) wurde in der vorliegenden Dissertation einer streng vergleichenden Analyse unterzogen, welche mit Hilfe moderner Methoden eine neue Sicht auf die Phylogenie der Arachniden eröffnet. Aus dem Vergleich mit den potentiellen Schwestergruppen (Xiphosura, Eurypterida) und mit Skorpionsfossilien erweist sich der einmalige Landgang eines gemeinsamen Vorfahrens aller rezent terrestrischen Arachniden. Buchlungen-Daten von 200 rezenten + 2 fossilen Skorpionen, 16 Geißelspinnen (Amblypygi), 17 Geißelskorpionen (Thelyphonida), einem Schizomiden (Schizomida), einem ausgestorbenen Trigonotarbiden (Trigonotarbida) und der Außengruppe, den rezenten Pfeilschwanzkrebsen (Xiphosura), wurden zu einem illustrierten Katalog zusammengestellt. Die unüberschaubare Vielfalt der oft graduell variierenden Strukturen macht die eindeutige Definition der Merkmale und auftretenden Merkmalszustände notwendig. Es wurden folgende 5 Merkmale definiert: (1) die Oberflächen der Atemlamellen, (2) der Lamellenrand, (3) der posteriore Stigmenrand, (4) der anteriore Stigmenrand und (5) die Wand des Atriums. Hierbei tragen die Merkmale 1-3 mit ihrer unerwarteten Fülle innerhalb der Skorpione maßgeblich zur Aufklärung ihrer Verwandtschaftsverhältnisse bei. Ähnliches wird von den Merkmalen 4 und 5 bezogen auf die Uropygi s. lat. vermutet. Ein sechstes Merkmal (Sensillen/Poren) wurde definiert, doch nur vereinzelt erfasst. Raster-Elektronenmikroskopie diente der Erfassung der cuticulären Feinstruktur der Buchlungen. Die Struktur der Buchlungen im Gesamten wurde mittels histologischer Schnittserien und mit auf µCT basierenden 3D-Rekonstruktionen untersucht. Für die Untersuchung von Trigonotarbiden-Fossilien wurde eine Methode entwickelt, die 3D-Rekonstruktion aus Sequenzen von Mikrofotos in unterschiedlichen Fokusebenen generiert.
Strict comparative analyses of the morphology of arachnid book lungs (Arachnida Lamarck, 1801 - Arthropoda: Chelicerata) were carried out in the present doctoral thesis using modern methods, resulting in a new perspective on arachnid phylogeny. Comparisons with potential aquatic sistergroups (Xiphosura and/or Eurypterida) and fossil scorpions give rise to the hypothesis of the unique terrestrialization of ancestors, which is common for all arachnids. Data from 200 Recent + 2 extinct scorpions, 16 whip spiders (Amblypygi), 17 whip scorpions (Thely-phonida), 1 schizomid (Schizomida), 1 extinct trigonotarbid (Trigonotarbida) and 1 outgroup - horseshoe crab (Xiphosura) are assembled into an illustrated catalogue of arachnid book lungs. Following the observations of these gradually differing cuticular structures the vast variation of book-lung fine structure across Arachnida requires unequivocal definition of characters and character states. Five characters are defined, which are assigned to distinct homologous book-lung structures: (1) the surface structure of the respiratory lamellae, (2) structure of the distal edges of the lamellae, (3) the posterior edge of the spiracle, (4) the anterior edge of the spiracle and (5) the structure of the wall lining the atrial chamber. Especially the book-lung characters 1-3 contain unexpected information, which helps resolve relationships within Scorpiones to a high degree, and characters 4 and 5 are of considerable importance for Uropygi s. lat. One sixth character (sensilla/pores) is mentioned, but sporadically examined. However, cuticular book-lung fine structure is studied using SEM, the gross morphology is reassessed using histological sectioning and 3D-reconstructions based on µCT. For investigations on trigonotabid fossils a new method yielding 3D-reconstructions from stacks of subsequent focal layers was developed.

Abstract Reactive oxygen species (ROS) can cause severe damage to cells and organs but they are also important mediators of inflammatory responses and cellular signalling. Due to the significant role of ROS, the cells have evolved a broad antioxidative system to regulate the concentration of these species. Peroxiredoxins (Prxs) are enzymes that participate in the regulation of the cellular redox-homeostasis by detoxifying hydrogen peroxide. Prxs are not classified as conventional antioxidant enzymes and their physiological role, whether protective or regulatory, is still unclear. The aim of this project was to study the localization and regulation of Prxs in normal human lung and also their role in selected lung disorders (pulmonary sarcoidosis, pleural mesothelioma, lung carcinomas and chronic obstructive disorder, COPD). Additionally the expression of thioredoxin (Trx) and thioredoxin reductase (TrxR) was analysed in the lung of smokers and COPD patients. These enzymes are important reductants in cell and Prxs are one of their targets. Lung is an important organ in the field of ROS and antioxidant research since it is especially vulnerable to exogenous oxidative stress caused by pollutants, cigarette smoke and also by high oxygen pressure. The results showed that all six human Prxs were expressed in healthy human lung but in a cell-specific manner. The most prominent expression was detected in the epithelium and in macrophages, the cells most prone to oxidative stress. There were also differences in subcellular locations of Prxs. The expression of Prxs in non-malignant lung diseases (pulmonary sarcoidosis and COPD) and in smoker's lung was very similar with that in normal lung. Higher expression of Prx V and VI was detected in a subpopulation of macrophages sampled from COPD patients' lung. In contrast, Trx expression was induced in the bronchial epithelium of smoker's lung. Differences in the expression compared to normal lung were seen in lung malignancies (pleural mesothelioma and lung carcinomas). Interestingly, different Prxs were highly expressed in different types of carcinomas. In pleural mesothelioma, all Prxs except Prx IV were highly expressed when compared to normal pleura, in adenocarcinoma Prxs I, II, VI and especially IV, and in squamous cell carcinoma Prxs I, II and IV were upregulated. Tests performed on cultured cells in vitro revealed only a minor increase in the Prx expression after severe oxidant stress in malignant lung cell line originating from alveolar type II pneumocytes (A549) or non-malignant cell line derived from bronchial epithelium. None of the tested growth factors or cytokines affected Prx expression or oxidation state, but severe oxidant stress influenced remarkably the oxidation state of the Prxs.

Radiation therapy has been successful in treating lung cancer patients, but its efficacy is limited by the inability to account for the respiratory motion during treatment planning and radiation dose delivery. Physics-based lung deformation models facilitate the motion computation of both tumor and local lung tissue during radiation therapy. In this dissertation, a novel method is discussed to accurately register 3D lungs across the respiratory phases from 4D-CT datasets, which facilitates the estimation of the volumetric lung deformation models. This method uses multi-level and multi-resolution optical flow registration coupled with thin plate splines (TPS), to address registration issue of inconsistent intensity across respiratory phases. It achieves higher accuracy as compared to multi-resolution optical flow registration and other commonly used registration methods. Results of validation show that the lung registration is computed with 3 mm Target Registration Error (TRE) and approximately 3 mm Inverse Consistency Error (ICE). This registration method is further implemented in GPU based real time dose delivery simulation to assist radiation therapy planning.
ID: 031001565; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Advisers: Sumanta N. Pattanaik, Anand P. Santhanam.; Title from PDF title page (viewed August 26, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 77-83).
Ph.D.
Doctorate
Computer Science
Engineering and Computer Science
Computer Science

Background: Venous thromboembolism, manifesting as deep vein thrombosis (DVT) and pulmonary embolism (PE), is a significant source of morbidity and mortality and a cause of postoperative complications after invasive surgery. These adverse events are more likely to occur in high risk patients, such as those with cancer or undergoing major surgery with the highest incidence peak taking place within the first month after surgery. Despite the issue being globally recognized, a lack of consensus regarding guidelines for prophylaxis post-discharge still exists. Aim: To determine the incidence of venous thromboembolism within a 30-day postoperative period after thoracotomy and lung lobectomy for lung malignancy, to assess a correlation of the above with administered prophylactic treatment. Method: A retrospective cohort study was conducted as a review of medical records of all patients, appertaining to Örebro county, who had undergone thoracotomy and lung lobectomy for lung cancer or secondary malignant tumor in the lung, during 2015-2017 at the department of Cardiothoracic and Vascular Surgery, Örebro University Hospital. An internally validated register was used to identify the patient population and partial collection of the data. Results: Of the 67 included patients 50,8% were men and the mean age of the population was 67,5 years. The VTE prevalence during the 30-day postoperative period was 1,5%. A total of 59,7% of the patients received thrombosis prophylaxis preoperatively, 98,1% postoperatively and 11,9 % after hospital discharge. Conclusion: The VTE prevalence of 1,5% in this study may suggest the current postoperative prophylactic regiment successful, yet VTE remains a clinically significant complication, and the need for well-defined guidelines is evident.

This thesis compares and contrasts currents- and varifolds-based diffeomorphic image registration approaches for registering tree-like structures in the lung and surface of the lung. In these approaches, curve-like structures in the lung—for example, the skeletons of vessels and airways segmentation—and surface of the lung are represented by currents or varifolds in the dual space of a Reproducing Kernel Hilbert Space (RKHS). Currents and varifolds representations are discretized and are parameterized via of a collection of momenta. A momenta corresponds to a line segment via the coordinates of the center of the line segment and the tangent direction of the line segment at the center. A momentum corresponds to a mesh via the coordinates of the center of the mesh and the normal direction of the mesh at the center. The magnitude of the tangent vector for the line segment and the normal vector for the mesh are the length of the line segment and the area of the mesh respectively. A varifolds-based registration approach is similar to currents except that two varifolds representations are aligned independent of the tangent (normal) vector orientation. An advantage of varifolds over currents is that the orientation of the tangent vectors can be difficult to determine especially when the vessel and airway trees are not connected. In this thesis, we examine the image registration sensitivity and accuracy of currents- and varifolds-based registration as a function of the number and location of momenta used to represent tree like-structures in the lung and the surface of the lung. The registrations presented in this thesis were generated using the Deformetrica software package, which is publicly available at www.deformetrica.org.

Le cancer du poumon est la principale cause de décès par cancer dans le monde. En dépit de la variété de traitements disponibles, tels que la chirurgie, la chimiothérapie, la radiothérapie et l’immunothérapie, la survie moyenne à 5 ans est de 60 %. L’une des raisons sous-jacente est une très grande variabilité de réponse au traitement, expliquée par les antécédents génétiques du patient et depuis peu par son microbiote. Le terme « microbiote » regroupe les bactéries, les archées, les champignons, les virus et les protistes qui colonisent notre organisme. Des études utilisant des modèles animaux montrent que le microbiote intestinal joue un rôle crucial dans la réponse de l’hôte au traitement, via la stimulation du système immunitaire. Dans ce contexte, plusieurs « axes de communication » entre le site intestinal et les sites tumoraux distaux commencent à émerger, y compris l’axe « intestin-poumon ». Cependant, le microbiote pulmonaire, qui pourrait directement influencer la réponse tumorale et interagir avec le microbiote intestinal, est pour l’heure peu caractérisé. Afin de développer cette idée d’un axe « intestin, poumon et cancer du poumon », nous avons inclus dans notre étude 18 patients atteints d’un cancer du poumon non à petites cellules (CBNPC) admissibles à la chirurgie. Nous avons analysé leurs microbiotes par séquençage à haut débit à partir de quatre échantillons différents de poumon (tissu sain, tissus péritumoral et tumoral et fluide de lavage broncho-alvéolaire LBA) mais également à partir d’échantillons de salive et de fèces. Nous avons également analysé plusieurs marqueurs immunitaires (infiltration lymphocytaire des tumeurs, profils Th et neutrophiles, cytokines dans le LBA et le sang), des marqueurs inflammatoires et enfin les acides gras à chaînes courtes dans les fèces. Une caractérisation détaillée de ces quatre types d’échantillons de poumons nous a permis de montrer que le microbiote du LBA présente une communauté nettement distincte de celle du tissu pulmonaire. Les tumeurs des lobes inférieurs prédisant le plus mauvais pronostic, nous avons décidé d’étudier le lien entre l’emplacement des tumeurs et la composition du microbiote. Les microbiotes du tissu péritumoral et du LBA ont été identifiés comme étant les plus impactés en terme d’abondance et de diversité ; la tumeur est quant à elle moins impactée. Cependant nous avons observé que le phylum des Firmicutes, décrit comme étant élevé dans les maladies pulmonaires obstructives chroniques, est plus abondant dans le microbiote des lobes inférieurs du poumon. Par conséquent, nous pouvons émettre l’hypothèse que l’augmentation des Firmicutes et les variations importantes du microbiote dans le tissu péritumoral pourraient être associés à une agressivité accrue des tumeurs du lobe inférieur. Nous avons ensuite démontré que la présence de ganglions lymphatiques (GL) métastatiques, marqueur d’un pronostic négatif dans le NSCLC, influence considérablement le microbiote local de par le profil respiratoire du tissu. Nous avons en effet observé que les bactéries anaérobies étaient plus abondantes dans les tumeurs en présence de LN métastatiques. Les bactéries aérobies sont quant à elles plus représentées dans les tumeurs sans GL métastatiques. Nous avons cependant observé la situation inverse dans les tissus extratumoraux. L’hypothèse avancée est celle d’une migration bactérienne en fonction des préférences de conditions de croissance, directement liées aux caractéristiques de la tumeur. Ceci nous permet de proposer plusieurs biomarqueurs pour la détection de GL métastatique, facilitant ainsi leur détection sans imposer de biopsie. Enfin, nous montrons que le microbiote du LBA est d’avantage associé à la réponse immunitaire locale et est indépendant de la présence de GL métastatique. Les recherches à venir porteront sur l’exploration de l’interaction entre le microbiote pulmonaire, l’immunité systémique et le microbiote intestinal
Lung cancer is the main cause of death by cancer worldwide. Despite the variety of available treatments, including surgery, chemotherapy, radiotherapy, and immune therapy, the average 5-year survival is 60%. One of the underlying reasons is a very high variability in patients’ susceptibility to treatment, explained by genetic background and since recently – our microbiota. The term microbiota includes bacteria, archaea, fungi, viruses and protists that inhabit our organism. The studies in animal models show that the gut microbiota (focused on bacteria) has a crucial role in host’s responsiveness to therapy through the stimulation of immune system. In this light, several “communication axes” between the gut and distal tumour sites have started to develop, including the “gut-lung” axis. However, the resident microbiota in the lungs that could directly influence the tumour response and interact with the gut microbiota has been scarcely characterised. To enable further development of the idea of the “gut-lung-lung cancer” axis, we included 18 non-small cell lung cancer (NSCLC) patients eligible for surgery and analysed the microbiota from four different lung samples (non-malignant, peritumoural and tumour tissue and bronchoalveolar lavage fluid; BAL), saliva and faeces by high-throughput sequencing. We also analysed several immune markers, as lymphocytic tumour infiltrate, Th and neutrophil profiles and cytokines in BAL and blood, and inflammatory markers in faeces along with short-chain fatty acids. Focusing first on the lungs, we show that BAL microbiota represents a significantly distinct community compared to lung tissue microbiota by providing detailed characterisation of the four different lung samples. Since tumours in lower lobes are reported as the ones with the worse prognosis, we investigated how the lobe location affected the microbiota composition. Peritumoural tissue and BAL microbiota were identified as the most affected in both abundance and diversity, and tumour as the least affected. However, phylum Firmicutes, previously reported as elevated in chronic obstructive pulmonary disease compared to controls, was found more abundant in microbiota from lower lung lobes. Therefore, we propose that both increase in Firmicutes and extensive changes in peritumoural tissue could be associated to increased aggressiveness of the lower lobe tumours. Next, we show that the presence of metastatic lymph nodes (LN), negative prognostic marker in NSCLC, significantly influence the local tissue microbiota in relation to its respiratory profile. We reported that anaerobic bacteria were more abundant within the tumour in the presence of metastatic LN, and aerobic bacteria within the one without it. Moreover, exactly inverse was observed for the same bacteria in extratumoural tissues. Along with migratory hypothesis depending on the bacterial preference for growth conditions shaped by tumour’s features, we propose several biomarkers for detection of metastatic LN that might facilitate their detection without imposing LN biopsy. Finally, we showed that BAL microbiota is the most associated to the local immune response and independent of the presence of metastatic LN. Future research will focus on the exploration of the interaction between the lung microbiota, systemic immunity and the gut microbiota

The primary aim of the project was to evaluate the epidemiological and genetic susceptibility factors associated with lung cancer, in the Liverpool Lung Project (LLP) population. The associated datasets available for research with the LLP dataset (questionnaire) were: Office of National Statistics (ONS), Health Episode Statistics (HES) data with comorbidity data, single nucleotide polymorphism (SNP) data of 570 cases from Liverpool, 3000 controls from the 1958 Birth Cohort. The epidemiological (HES) data was used to study the effect of Charlson (CCI) and Elixhauser comorbidity index (ECI) on the incidence of lung cancer using the Cox proportional hazard regression and use the same HES data to design a 5-year sex specific incidence model for lung cancer with crucial covariates. The ECI and CCI were significant in both univariate and multivariate analyses adjusted for age at the start of the study, sex and smoking pack years. The developed models had a good discriminatory power (AUCmale = 0.73; AUCfemale = 0.77) when internally validated using a 10-fold cross validation. The genetic data for the LLP lung cancer cases was used in several contexts: i) to identify SNPS associated with lung cancer under a range of allelic models (additive, dominant, recessive and genotypic), using the Wellcome trust 1958 Birth Cohort as a control dataset; ii) to identify SNPs associated with cause specific and overall survival in lung cancer patients, utilising the Cox proportional hazard model with adjustment for various covariates; and iii) to identify gene pathways that are associated with lung cancer survival using the random forest survival method. SNPs within the genes PRDM11, ZNF382 and HMGA2 were identified in the genome wide case-control study when using the additive, dominant or genotypic models, whereas the recessive model identified the gene ITIH2. Significant SNPs (p≤10-6) associated with cause-specific survival in early stage cases were rs10230420 (WIPF3), rs3746619 and rs3827103 (both in MC3R). In advanced stage cases, significant SNPs were rs1868110 (NEK10) and rs2206779 (AF357533). For the overall survival analysis, significant SNPs were rs10230420 (WIPF3), rs2056533 (ZBTB20) and rs6708630 (CYS1) in early stage cases, whereas rs1868110 (NEK10) and rs2206779 (AF357533) were significantly associated with overall survival in advanced stage NSCLC cases. The pathway analysis using the random survival forest method was undertaken on 18 pathways for both cause-specific and overall survival of lung cancer cases. The results were consistent with apoptosis, base excision repair and mismatch repair being pathways influencing survival.

Thoracic surgical procedures require partial or complete airway separation and the opportunity to exclude one lung from ventilation (one-lung ventilation, OLV). OLV is commonly associated with profound pathophysiological changes that may affect the postoperative outcome. It is injurious in terms of increased mechanical stress including alveolar cell stretch and overdistension, shear forces secondary to repeated tidal collapse and reopening of alveolar units and compression of alveolar vessels. Ventilation and perfusion distribution may thus be affected during and after OLV. The present studies investigated the influence of OLV on ventilation and perfusion distribution, on the gas/tissue distribution and on the lung histomorphology in a pig model of thoracic surgery. Anaesthetised and mechanically ventilated piglets were examined. The ventilation and perfusion distribution within the lungs was assessed by single photon emission computed tomography. Computed tomography was used to establish the effects of OLV on dependent lung gas/tissue distribution. The pulmonary histopathology of pigs undergoing OLV and thoracic surgery was compared with that of two-lung ventilation (TLV) and spontaneous breathing. OLV induced hyperperfusion and significant V/Q mismatch in the ventilated lung persistent in the postoperative course. It increased cyclic tidal recruitment that was associated with a persistent increase of gas content in the ventilated lung. OLV and thoracic surgery as well resulted in alveolar damage.  In the present model of OLV and thoracic surgery, alveolar recruitment manoeuvre (ARM) and protective ventilation approach using low tidal volume preserved the ventilated lung density distribution and did not aggravate cyclic recruitment of alveoli in the ventilated lung. In conclusion, the present model established significant alveolar damage in response to OLV and thoracic surgery. Lung injury could be related to the profound pathophysiological consequences of OLV including hyperperfusion, ventilation/perfusion mismatch and increased tidal recruitment of lung tissue in the dependent, ventilated lung.  These mechanisms may contribute to the increased susceptibility for respiratory complications in patients undergoing thoracic surgery. A protective approach including sufficient ARM, application of PEEP, and the use of lower tidal volumes may prevent the ventilated lung from deleterious consequences of OLV.

Alveolar fluid clearance is driven by vectorial Na+ transport and promotes postnatal lung adaptation. The effect of insulin on alveolar epithelial Na+ transport was studied in isolated alveolar cells from 18–19-day gestational age rat fetuses. Equivalent short-circuit currents (ISC) were measured in Ussing chambers and different kinase inhibitors were used to determine the pathway of insulin stimulation. In Western Blot measurements the activation of mediators stimulated by insulin was analyzed. The ISC showed a fast dose-dependent increase by insulin, which could be attributed to an increased ENaC (epithelial Na+ channel) activity in experiments with permeabilized apical or basolateral membrane. 5-(N-Ethyl-N-isopropyl)amiloride inhibition of ISC was not affected, however, benzamil-sensitive ISC was increased in insulin-stimulated monolayers. The application of LY-294002 and Akti1/2 both completely blocked the stimulating effect of insulin on ISC. PP242 partly blocked the effect of insulin, whereas Rapamycin evoked no inhibition. Western Blot measurements revealed an increased phosphorylation of AKT after insulin stimulation. SGK1 activity was also increased by insulin as shown by Western Blot of pNDRG1. However, in Ussing chamber measurements, GSK650394, an inhibitor of SGK1 did not prevent the increase in ISC induced by insulin. The application of IGF-1 mimicked the effect of insulin and increased the ENaC activity. In addition, an increased autophosphorylation of the IGF-1R/IR was observed after insulin stimulation. We conclude that insulin rapidly increases epithelial Na+ transport by enhancing the activity of endogenous ENaC through activation of PI3K/AKT in alveolar cells.

This study examined the effects of lung expansion and changes in temperature on fluid movement by the lungs in the initial period after birth. In addition, experiments with amiloride support the belief that fluid reabsorption acts via a sodium transport mechanism. Lungs from fetal guinea pigs (56-67 days of gestation) were supported in vitro for three hours, and lung liquid production rates were measured using a dye dilution technique. The average production rate in the first hour of untreated preparations was 1.30 ±0.22 ml/kg body weight per hour, and this did not change significantly during the remainder of the experiment (n=30). This rate is comparable to secretion rates previously reported from chronically catheterized sheep. In 36 further preparations, the lungs were transferred from 37°C to fresh Krebs-Hanseleit saline at one of the following temperatures, for one hour (an ABA design): (a) 29°C; (b) 32°C; (c) 34°C; (d) 35°C; (e) 36°C; (f) 39°C. In all cases, the temperature change resulted in an immediate and significant fall in secretion. All lungs showed a tendency towards recovery when returned to starting conditions, except those subjected to a temperature increase. Reductions of 2-3°C, those normally seen in the delivery room, had the greatest effect and caused not only a decrease in secretion, but promoted fluid reabsorption. Amiloride at 10⁻⁶M had no effect on control preparations, but completely blocked the reabsorption stimulated by a temperature drop of 2°C. Expansion of the lungs, which occurs naturally as a newborn attempts to take its first breaths, was also examined. Thirty fetal lungs were expanded by one of the following amounts: (a) 18%; (b) 31%; (c) 43%; (d) 50%; (e) 72%. All expansions resulted in a significant fall in secretion rate, with the effect being proportional to the degree of expansion. Amiloride at 10⁻⁶M again blocked the strong reabsorption occurring with 70% expansion. Further studies investigated the possibility that expansion causes reabsorption via the local release of a substance occurring in the lungs. When one set of lungs was expanded in the presence of a second, unexpanded set, both showed a significant decrease in secretion, suggesting that the expanded lung had released some factor which affected the otherwise untreated lung. However, studies with α- and β- adrenergic blockers showed that it is unlikely the expanded lung was liberating either adrenaline or nor-adrenaline. The results of this study show that two changes which are likely to occur in the period immediately after birth, namely a 2-3°C decrease in core temperature, and lung expansion, may be important in promoting the vital reabsorption of fluid. They suggest that expansion may release substances locally in the lungs which stimulate this reabsorption, and that the fluid is removed from the potential air spaces via sodium transport mechanisms.
Science, Faculty of
Zoology, Department of
Graduate

A model was developed to account for the static elastic behaviour of the lung tissue strip in terms of distributions of collagen and elastin fibers. Distributions of collagen fiber lengths and elastin fiber stiffnesses were determined by fitting the model to data from dog lung tissue strips. These distributions followed 1/f power-laws for more than 95% of the data. Computer simulations of two dimensional tissue strip models with 1/f distributions of collagen fiber lengths also predicted realistic stress-strain curves. The simulations illustrated the gradual development of geometric and stress heterogeneity throughout the tissue as the collagen fibers were recruited during stretch. This model suggests a mechanistic basis for the shape of the pressure-volume curve of whole lung. It also indicates how this curve may be affected by changes in tissue collagen and elastin similar to the changes occurring in the diseases of pulmonary emphysema and fibrosis. Nonparametric block-structured nonlinear models for describing both the static and dynamic stress-strain behaviour of the lung were applied to dog lung tissue strips and to whole rat lungs in vivo. Both the Wiener and Hammerstein models accounted for more than 99% of the tissue strip data, although the Hammerstein model was more consistently accurate across a range of perturbation amplitudes and operating stresses. Plastic dissipation of energy within the lung tissue strip was estimated at less than 20% of the total dissipation during slow sinusoidal cycling. The Hammerstein model was also the best of those investigated for describing the rat lung data in vivo, although there were dependencies of the model parameters on perturbation amplitude and operating point that indicate that a more complicated model is required for the whole lung. Finally, construction of a fiber recruitment model for the dynamic mechanical behaviour of lung tissue strips was attempted. However accurate reproduction of measured behaviour was no

Background: Lung cancer was the fifth leading cause of mortality globally in 2010, and the leading cause of cancer mortality in Canada, representing 26% of all cancer deaths for both men and women in 2017. Radon is a very modifiable environmental exposure that is the second most important cause of lung cancer. Objectives: The objectives of this thesis are to quantify the lung cancer burden associated with residential radon and to identify the most cost effective mitigation options to reduce residential radon in Canada. Methods: The global burden of lung cancer mortality attributable to radon in 2012 was estimated from the 66 countries for which a representative national radon survey was available, using several different models for excess relative risk (ERR) of lung cancer from radon studies. Cost-utility analyses are conducted for 20 practical radon interventions scenarios to reduce residential radon exposures in new and existing housing in Canada, each province/territory and 17 census metropolitan areas. A societal perspective and a lifetime horizon are adopted. A Markov cohort model and a discrete event simulation are used to model residents by household, based on a period-life table analysis, at a discount rate of 1.5%. Results: The estimates of the global median PAR were consistent, ranging from 16.5% to 13.6% for the three ERR models based on miners, and the mean estimates of PAR for Canada ranged from 16.3% to 14.6%. It is very cost effective to install radon preventive measures in new construction compared to no radon control in all regions across Canada. At a radon mitigation threshold of 100 Bq/m3, the sequential analysis recommends the combination of the activation of preventive measures in new housing with the mitigation of existing housing at current testing and mitigation rates for cost effectiveness thresholds between 51,889 and 92,072 $/QALY for Canada, between 27,558 and 85,965 $/QALY for Manitoba, and between 15,801 and 36,547 $/QALY for the Yukon. The discounted ICER for screening and mitigation of existing housing at current rates relative to no radon control measures is 62,451 (66,421) $/QALY using a Markov cohort model (discrete event simulation model) for mitigation of housing above a threshold of 200 Bq/m3, and is 58,866 (59,556) $/QALY using a Markov cohort model (discrete event simulation model) for mitigation of housing above a threshold of 100 Bq/m3. Conclusions: Cost effective residential radon interventions should be implemented across Canada to reduce exposures to this very modifiable cause of lung cancer and to help reduce the increasing lung cancer burden in an ageing Canadian population.

Introduction Lung cancer is the most common cause of cancer-related death in the United States (US). Tobacco smoking is a well-recognized cause of lung cancer. About 2% of the United States (US) population lives in Tennessee (TN). Nearly 21 % of TN adults are current smokers as per 2019 data, compared to 14% across the US. The percentage of smokers has historically been high in TN and its surroundings. This can be attributed to the area's socio-economic and cultural characteristics, along with large areas of tobacco farming in the region. This increases the risk of lung cancer in the TN population. Surveillance Epidemiology and End Results Program (SEER) is a collection of cancer registries across the US, covering about 35% of the US population (TN cancer registry is not a part of SEER). Our study compares lung cancer incidence and characteristics in the TN cancer registry with the SEER 18 registry. Materials and Methods Data were collected from the TN cancer registry and SEER separately for lung and bronchial cancer. Data was analyzed for different histological subtypes, age groups, gender, stage at diagnosis, and rural/urban residence. Stata and Microsoft Excel were used in data analysis. A Chi-square test was used to calculate the statistical significance. Results From 2008 to 2017, 58644 cases of lung cancer were reported in the Tennessee cancer registry. During the same period, 519112 cases were reported in the SEER registry. The most frequent histological subtype of lung cancer in TN and SEER was adenocarcinoma (frequency of 17,503 Vs. 182346), followed by squamous cell carcinoma and small cell carcinoma. Most cancers in TN and SEER were diagnosed at stage of distant metastasis (46% vs. 52% ), followed by regional metastasis, localized, and in situ (Image1). The frequency of lung cancer diagnosis was high among those older than 65 in TN and SEER (64% vs. 69%). Males had a higher incidence of lung cancer in both registries. Most lung cancers were reported in the urban area in both registries. Chronic obstructive pulmonary disease was the most commonly reported secondary diagnosis (3,099), followed by pleural effusion in the TN database; the comparable data were not available in SEER. Relative survival at 12 months and five years for lung cancer in TN were 46.6 % and 19.5 % (Vs. 46.4% and 19.9% in SEER) Discussion and Conclusion If both registries were perfect, then lung and bronchial cancer incidence will be 9241 and 6048 per million in ten years in TN and SEER, respectively. But after careful analysis, we conclude that such analysis will be erroneous. The proportion of different histological types, stage at diagnosis, age groups, and gender were in the same order in both groups. Although chi-square test values are significant for all the variables, we infer no conclusion considering the data's inherent bias. Further in-depth analysis of the data is required.

Peru is a South American nation with a growing and aging population of 31 million people with a life expectancy at birth of 76.7 years. The country is divided into 25 regions, 79% of the population is urban, and Lima, the capital, concentrates more than a third of the population.1 Although Peru is an upper-middle-income country, health expenditure represents only 5.1% of the gross domestic product, which is lower than the average of Latin America and the Caribbean (LATAM) (8.56%).2 Out-of-pocket health expenditure is 30.9%.3 Peru has a comprehensive National Cancer Plan and two population-based cancer registries in Lima and Arequipa.
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Dissertation (PhD)--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: Background to the study OLA can give rise to certain problems: 1. A significant decrease in lung volume is reported to occur in the dependent lung during OLA in the LDP. This decrease in lung volume can result in an acute increase in opposition to RV ejection. The potential problem is that the right ventricle is a thin walled structure that can generate considerably less work than the thicker walled LV. It possesses little reserve to deal with an acute rise in afterload as may occur during acute lung injury or after lung resection. Therefore, this increase in afterload during OLA may potentially impair RV-PA coupling. Albeit this potential problem exists, the changes in RV afterload and how the right ventricle performs during OLA have not been well studied. 2. Arterial hypoxemia, due mainly to venous blood being shunted via the non-ventilated lung, may present a clinical problem during one lung ventilation. a. The relative resistances of the pulmonary vascular beds of the dependent ventilated and nondependent non-ventilated lungs are an important factor governing shunting and thus arterial oxygenation during one lung anesthesia. A high non-ventilated lung PVR and low ventilated lung PVR will facilitate good arterial oxygenation during OLA. An increase in non-ventilated lung PVR is governed predominantly by hypoxic pulmonary vasoconstriction. A low opposition to pulmonary blood flow in the dependent lung is facilitated predominantly by a high alveolar oxygen tension and normal lung volume, albeit other factors also play a role in this regard. b. The saturation and oxygen content of mixed venous blood will contribute significantly to the arterial oxygenation in the presence of a large shunt as occurs during OLA. i. On the one hand, venous desaturation as a cause of hypoxemia during one lung anesthesia has not as yet been systematically addressed in the literature. ii. On the other hand, if RV afterload increases to such a degree that it leads poor RV performance, this may cause impairment of global circulatory efficiency and lead to mixed venous desaturation. The question that has been raised is whether inotrope infusions could improve RV and LV performance, cardiac output, and thereby the efficiency of the circulation. Increases in the efficiency of the circulation will result in an improvement in mixed venous and arterial oxygenation in the presence of a large shunt. Nonetheless, the administration of inotrope infusions in the presence of a shunt and during OLA has been reported to aggravate hypoxemia. Thus at the time of conducting the study, conflicting reports of whether increasing cardiac output and thereby mixed venous oxygenation would increase or decrease arterial oxygenation during OLA In the light of the above, the researcher thus investigated RV afterload, RV performance and coupling to its load during OLA. The study also addressed the question whether different levels of inotrope infusion or PEEP hadbeneficial or deleterious effects on RV afterload, RV performance and coupling to its load during OLA. Furthermore, if cardiac output increased during OLA secondary to the infusion of inotropes, would this improve the efficiency of the circulation, mixed venous oxygenation and thus the arterial oxygenation during OLA, or would it worsen shunt and arterial oxygenation during OLA? Control group: OLA and the opposition to pulmonary flow Pulmonary arterial elastance increased by between 18 to 36% during OLA and mean PAP rose by 32% after initiation of OLA This increase in mean PAP on initiation of OLA is greater than that observed by certain investigators but similar to that seen previously in patients with damaged lungs. The question arose as to why pulmonary artery pressure rises during OLA? From consideration of Ohm’s law, pressure may be regarded as the product of flow and resistance (Mark, Slaughter et al. 2000). The increase in mean PAP during OLA is due to two reasons. 1. Firstly, the pressure versus flow curve is likely to be steeper during OLA. This is because pulmonary vascular recruitment and dilatation (pulmonary vascular reserve) is more limited in scope in these patients than is usual and most likely accounts for the increase in pulmonary artery pressure during OLA. The reasons for the limited pulmonary vascular reserve in the DL during OLA include: a. The pulmonary vascular bed of patients subjected to OLA is frequently abnormal because of its underlying pathology, b. During OLA in the lateral decubitus position, lung volume decreases to a greater degree than during two-lung anesthesia (Klingstedt, Hedenstierna et al. 1990). c. This decrease in lung volume will be further aggravated by DLT malpositions, secretions and blood, and absorption atelectasis due to the use of high concentrations of oxygen (Hedenstierna 1998; Krucylak, Naunheim et al. 1996). d. Excessive amounts of extrinsic or intrinsic PEEP during OLA can compress the intra-alveolar capillaries and deleteriously affect the pulmonary vascular resistance (Ducros, Moutafis et al. 1999; Inomata, Nishikawa et al. 1997; Bardoczky, Yernault et al. 1996; Yokota, Toriumi et al. 1996). 2. Secondly, there is greater flow through this vascular bed that possesses a higher resistance. It is noteworthy that the increase in mean PAP did not exceed a value of 25 mm Hg during OLA, even though cardiac output increased by 30%. However, in studies conducted in patients with “damaged lungs”, greater increases in PA pressure (accompanied by a decrease in RVEF) have been reported to occur on PA ligation. A question arises as to why differences exist between PA clamping and OLA? The answer may well be that the observed plateau in the rise of PA pressure during OLA is as a result of progressive diversion of flow to the NDL as PA pressure rises. Support for such a suggestion comes from the observation that concomitant with increases in PA pressure during OLA, HPV is progressively inhibited and shunt fraction progressively rises. This increase in shunt fraction that has been observed to occur as PA pressure rises, reflects an increase in diversion of pulmonary blood flow to the NDL. The impact of diversion of this blood to the NDL is that it possibly acts as a safety mechanism limiting increases in PA pressure and other indices of opposition to pulmonary flow during OLA. This “blow-off effect” will protect the RV until PA clamping occurs.Control group: OLA and RV function The current study represented the opportunity to investigate the significance of the abovementioned increases in PA pressures and elastance on RV performance during OLA. The current study indicates that at the moderate (30%) increases in PAP that accompanied the initiation of OLA, RV performance, as judged by stroke volume, cardiac index, RVEF and RVSWI, did not deteriorate compared to the baseline awake status. In fact, cardiac output increased following surgical incision: this was probably due to sympathetic nervous system stimulation. This observation also fits in with other studies in which RV performance usually only begins to deteriorate when indices of opposition to RV ejection reach 200 to 250% of baseline. Furthermore, a constant preload, as indicated by unchanged central venous and pulmonary artery wedge pressures, and right ventricular end-diastolic volumes were observed throughout the study period. In other words, this increase in RV afyterlad did not cuse the RV to dilate durign OLA. The relationship between stroke work and afterload will vary, depending on the contractile reserve of the ventricle. In this regard, it could be concluded that under the conditions operative in the current study, the RV was operating on the upslope of the RVSWI versus Ea relationship. This supports the observation that RV function is well preserved during OLA. In conclusion, regarding the indices of opposition to pulmonary flow and RV performance during OLA, it can be concluded that: 1. Opposition to RV ejection increases. This is evidenced by a 30% rise in mean PAP and 18 to 36% increase in pulmonary arterial elastance. 2. Right ventricular performance as indicated by RVSWI, RVEF and stroke volume does not decrease during OLA compared with when the patients awake or subjected to two-lung anesthesia. 3. Furthermore, coupling between the RV and its load is well preserved during OLA. This would imply that the RV operates at close to maximal efficiency during OLA and that RV stroke work reserve is present during OLA. It is likely that the RV, which continues operating as a flow pump as it does in normal life, easily copes with the small increases in RV afterload during OLA. Dobutamine during OLA: opposition to pulmonary flow and RV performance The effects of dobutamine infusions on RV performance during OLA can be summarised as follows: 1. Low rates of dobutamine infusion (3 ug.kg-1.min-1) increased cardiac output, stroke volume, and RVSWI. The administration of dobutamine 3 ug.kg-1.min-1 was not accompanied by increases in RV afterload. Therefore, low infusion rates of dobutamine did benefit RV-PA coupling during OLA. 2. However, administration of higher dosages of dobutamine (5 and 7 ug.kg-1.min-1) during OLA was associated with increases in certain indices of opposition to pulmonary blood flow. For example, PA elastance, mean PA pressure, and PVR increased by 30% to 40% compared to both when the patients were awake and when both lungs were being ventilated. Furthermore, PA compliance decreased by up to 61% when dobutamine 5 and 7 ug.kg-1.min-1 were infused compared to the OLA step when dobutaminewas not administered. The increases in mean PAP and PVR are considered to be of limited clinical significance. However, the decrease in PA compliance during the infusion of the highest dosage of dobutamine is clinically significant. PA compliance represents one of the factors determining vascular impedance in the Windkessel model of the circulation. The increases in opposition to pulmonary flow and lack of progressive increase in indices of RV performance are in contrast to what is expected to occur on administration of increasing dosages of the inotrope and pulmonary vasodilator, dobutamine. The reasons for the increase in opposition to pulmonary flow include exhaustion of the pulmonary vascular reserve during OLA at the high cardiac indices of 5 to 5.5 l.min-1.m-2. This aspect overshadowed the expected pulmonary vasodilator effects of dobutamine. Moreover, it is probable that the increase in RV afterload was significant enough to prevent right ventricular performance increasing as would be expected with the administration of progressively higher dosages of inotrope. While dobutamine was being administered during OLA, mean PAP increased to a maximum of 24.9 ± 6.2 mm Hg at a cardiac index of 5.5 ± 1.2 l.min-1.m-2. However during OLA, in the control group, mean PAP was 24.0 ± 7.7 mm Hg at the maximum cardiac index of 4.4 ± 1.1 l.min-1.m-2. This represented a relatively limited rise in PA pressure compared with administration of dobutamine alone. The most likely reason why there may have been a limited increase in mean PAP while dobutamine was being administered is that the “blow off” effect of the NDL vasculature limited the rise in PA pressure. Oxygenation during OLA With regard to oxygen flux, venous and arterial oxygenation during OLA in the control group, the following was observed: 1. Induction of anesthesia and the approximately 1O Celsius decrease in temperature induced an approximately 40% decrease in VO2 that continued during OLA. 2. Initiation of OLA resulted in an increase in cardiac output compared to baseline OLA and awake states. 3. The consequence was an increase in S􀀀��������O2 from 75% and P􀀀��������O2 from 5.4 kPa when the patients were awake to a P􀀀��������O2 of 9.0 ± 1.7 kPa and S􀀀��������O2 of 90.6 ± 4.7% during one-lung anesthesia. 4. During OLA, the significant increase in venous oxygenation resulted in an increase in arterial oxygenation compared to the awake state in spite of the approximately 37% shunt occuring during OLA. 5. Under conditions in the present study, dobutamine administration during OLA did not improve, but maintained the already high venous and arterial oxygenation compared with OLA alone. Therefore, the study hypothesis, that dobutamine would induce improvement in RVF and the increase in cardiac output during OLA would improve arterial oxygenation, does not hold in the current study. The hypothesis that dobutamine administration and improving cardiac output during OLA would increase arterial oxygenation was therefore rejected. However, the rejection of the hypothesis means that the findings of the current study are in contrast to the findings of Mathru et al, and Nomoto and Kawamura. These authors demonstrated that inotrope administration resulted in an increase in arterial oxygenation. Nonetheless, the different results are not at odds with each other. In fact, these differences help to clarify the effect of increases in cardiac output on arterial oxygenation in the presence of asignificant shunt. The differences between the studies can be explained in the following way. Conditions in the current study resulted in a favourable DO2/VO2 ratio and a high starting P􀀀��������O2 even before dobutamine administration was commenced. Therefore the venous saturations were on the flat part of the oxygen dissociation curve and also on the flat part of the relationship between cardiac output and arterial oxygen content originally described by Kelman, Nunn and colleagues. Further increases in cardiac output and the DO2/VO2 ratio would not be expected to, and did not, increase P􀀀��������O2, S􀀀��������O2, or C􀀀��������O2. Thus, arterial oxygenation content and saturation did not change subsequent to the increase in cardiac output associated with the administration of dobutamine in the current study. In contrast, in the Mathru study, the low starting venous saturations and tensions were improved by increases in the DO2/VO2 ratio. As the starting venous saturation was “low,” significant benefit in arterial oxygenation was obtained on increasing cardiac output in that study. One significant concern for the clinician regarding the administration of the inotrope dobutamine during OLA is that it may increase shunt fraction (Qs/Qt) and thereby decrease arterial oxygenation during one lung ventilation. The influence of dobutamine on arterial oxygenation during OLA may theoretically be related to the balance of the following divergent effects: 1. By improving the relationship between oxygen delivery and consumption, dobutamine increases P􀀀��������O2. This increase will benefit arterial oxygenation in the presence of a large shunt, 2. The above has to be weighed against possible increases in VO2 induced by dobutamine, the consequence of which will be a decrease in P􀀀��������O2. Such increases in VO2 were not seen on administration of dobutamine in the current study, 3. An increase in PA pressure accompanying the increased cardiac output will oppose HPV and increase shunt in both the dependent and non-dependent lungs, 4. Direct inhibition of HPV by dobutamine and, 5. The influence of P􀀀��������O2 on HPV (i.e. high levels of venous oxygenation will inhibit whereas low levels will potentiate HPV). Nonetheless, in spite of the concerns (risk) of hypoxemia on administering dobutamine during OLA, dobutamine administration did not decrease PaO2 or arterial oxygen saturation, and neither did it increase the cost of oxygenation compared to when OLA was conducted in the absence of dobutamine infusions. In addition, the findings of studies conducted by Mathru and colleagues, Nomoto and Kawamura and the current study indicate that under usual clinical conditions present during OLA in the LDP, the administration of low dosages of dobutamine do not increase shunt fraction. In fact, the beneficial effect of the increase in cardiac output on venous oxygenation resulted in an increase in arterial oxygenation in the study by Mathru and colleagues; similar mechanisms were most likely operative in the study conducted by Nomoto and Kawamura. Therefore, there is currently no evidence that the administration of dobutamine in dosages of up to 7 ug.kg-1.min-1 increases shunt and worsens arterial oxygenation in humans subjected to OLA in the LDP. It is apparent that the vasodilatory effects of dobutamine resulting in a possible increase in shunt fraction (Qs/Qt) is therefore not the only factor to consider when studying its effects on arterial oxygenation. What is also of great relevance whenconsidering the effects of an inotrope on arterial oxygenation is the effect of inotropic drugs on the venous oxygen content. It is possible that Qs/Qt could be increased by the administration of inotrope. Nonetheless, if venous oxygenation is favourably affected by the administration of dobutamine, then a depressant effect on arterial oxygenation by an increase in the amount of blood passing via the shunt may be negated. If the increase in venous oxygenation is very significant, there may even be benefits in terms of arterial oxygenation, as was the case in the current study. This approach to how the quality of the blood passing via the shunt affects arterial oxygenation shifts the emphasis on prevention and treatment of hypoxemia during OLA from the lung to the efficacy of the circulation. In other words, the emphasis is shifted from what predominantly happens to the non-ventilated lung (HPV) to primarily the efficacy of oxygen flux during OLA. Extrinsic and intrinsic PEEP and OLA The effects of PEEP on hemodynamics and oxygenation observed during OLA in the current study may be summarised as follows. When PEEP5 was applied to the DL during OLA in the current study: 1. Neither right ventricular function, hemodynamics, oxygen flux nor arterial oxygenation was affected by the application of PEEP5 compared to the step when no external PEEP was applied. 2. Significant amounts of intrinsic PEEP were present during OLA in the control group patients. The degree of intrinsic PEEP was weakly related to the degree of obstructive airways disease present on preoperative LFT’s. 3. The most likely reason why PEEP5 did not make a difference to oxygenation or hemodynamics was the existence of similar amounts of intrinsic PEEP during OLA. These findings confirm Myles’s contention that low levels of intrinsic PEEP may have salutary effects on oxygenation during OLA. When PEEP10 was applied to the DL during OLA in the current study, it led to a decrease in stroke volume. This decrease is predominantly due to a decrease in preload, as PVR does not increase to levels that are known to impair RV performance. The decrease in the DO2/VO2 ratio that was induced by PEEP10 predictably decreases P􀀀��������O2 and can potentially lead to impairment of arterial oxygenation. It can therefore be concluded that greater (excessive) amounts of PEEP under more unfavourable circulatory conditions than were observed in the current study, may have deleterious cardio-respiratory effects. In summary, optimising DL volume plays an important role in determining arterial oxygenation. However, the therapeutic index for PEEP is narrow and the anesthesiologist needs to know firstly when the lung volume of the DL approaches FRC and secondly, how to avoid dynamic hyperinflation of that lung. One significant problem is that the best method of monitoring FRC during OLA is not clear at present.
AFRIKAANSE OPSOMMING: Agtergrond tot die studie Eenlongnarkose mag tot sekere probleme aanleiding gee. ’n Betekenisvolle afname in volume van die onderlong vind in die laterale decubitus posisie tydens eenlongnarkose plaas. Hierdie afname in longvolume mag egter ’n akute verhoging in regter ventrikulêre nalading tot stand bring. Die probleem is egter dat die regter ventrikel ’n dunwandige struktuur is wat potensieel baie minder werk as die dikwandige linker ventrikel kan genereer. Die regter ventrikel het min reserwe om ’n akute verhoging in nalading te weerstaan soos wat gebeur met akute longbesering of na longreseksie. Dus die verhoging in nalading wat gepaard gaan met eenlongnarkose mag die koppeling tussen die regter ventrikel en die pulmonale arterie belemmer. Alhoewel hierdie potensiële probleem bestaan, is die verandering albei in regter ventrikulêre nalading en hoe die regter ventrikel funksioneer tydens eenlongnarkose nog nie goed bestudeer nie. 1. Arteriële hipoksemie, hoofsaaklik te wyte aan die groot aftakking via die long wat nie geventileer word nie, mag kliniese probleme tydens eenlongnarkose teweegbring. 2. Die weerstand wat die pulmonale vaskulêre beddens van die geventileerde en nie-geventileerde longe bied teen bloedvloei is belangrike faktore wat aftakking en dus arteriële oksigenasie tydens eenlongnarkose beheer. ’n Hoë weerstand van die nie-geventileerde long en ’n lae weerstand van die geventileerde long se pulmonale vaskulêre beddens sal bevredigende arteriële oksigenasie tydens eenlongnarkose fasiliteer. ’n Verhoging in die pulmonale vaskulêre weerstand van die nie-geventileerde long is hoofsaaklik te wyte aan hipoksiese pulmonale vasokonstriksie. ’n Lae pulmonale vaskulêre weerstand in die geventileerde onderlong is hoofsaaklik gefasiliteer deur ’n hoë alveolêre suurstofspanning en ’n normale long volume, alhoewel alle faktore ook ’n rol in hierdie verband speel. 3. In die teenwoordigheid van die groot aftakking wat bestaan tydens eenlongnarkose, sal die saturasie en suurstof inhoud van gemeng veneuse bloed ’n betekenisvolle bydrae aan arteriële oksigenasie maak. a. Veneuse saturasie as ’n oorsaak van hipoksemie tydens eenlongnarkose, is nog nie sistematies in die literatuur ondersoek nie. b. Indien regter ventrikulêre nalading tot so ’n mate verhoog dat dit tot swak ventrikulêre uitwerp lei, mag dit ’n oorsaak wees van ontoereikendheid van die globale bloedsomloop en tot gemeng veneuse desaturasie lei. Die vraag is dus of verhoging van die kardiale omset deur inotrope ondersteuning die toereikendheid van die sirkulasie kan verbeter. Verbeterde sirkulasie toereikendheid sal tot ’n verhoging in gemeng veneuse en arteriële oksigenasie lei in die teenwoordigheid van ’n groot aftakking. Nietemin, die toediening van inotrope in die teenwoordigheid van ’n groot aftakking tydens eenlongnarkose gerapporteer om hipoksemie te vererger tydens eenlongnarkose. Dus ten tye van die uitvoer van dié studie, is daar uitdrukking gegee tot teenstrydige opinies in die literatuur oftewel verhoging in kardiale omset arteriële oksigenasie sal verbeter of versleg tydens eenlongnarkose.In die lig van die agtergrond hierbo, het die navorser dus regter ventrikulêre nalading, regter ventrikulêre funksie en koppeling van die regter ventrikel met sy lading tydens eenlongnarkose ondersoek. Die studie het ook die vraag benader of inotroop infusies of PEEP goeie of slegte gevolge sou hê op regter ventrikulêre nalading, regter ventrikulêre funksie en koppeling van die regter ventrikel aan sy lading tydens eenlongnarkose. Sou die kardiale omset en die toereikendheid van die sirkulasie sou verbeter sekondêr tot die toediening van inotrope tydens eenlongnarkose, gemeng veneuse oksigenasie en dus arteriële oksigenasie tydens eenlongnarkose verbeter, of sou dit aftakking en arteriële oksigenasie versleg tydens eenlongnarkose? Kontrole groep Pulmonêre elastansie het tussen 18 en 36% verhoog en gemene pulmonale arterie druk het met 32% tydens eenlongnarkose vermeerder. Die verhoging in gemene pulmonale arterie druk met die aanvang van eenlongnarkose is groter as die waardes gesien deur sekere navorsers maar gelyk met waardes gevind in pasiënte met beskadigde longe. Die vraag ontstaan dan hoekom styg pulmonale arterie druk tydens eenlongnarkose? volgens Ohm se Wet, mag druk as die veelvoud van vloei en weerstand beskou word. Die verhoging in gemene pulmonale arterie druk tydens eenlongnarkose is daarvolgens hoofsaaklik te wyte aan twee redes. 1. Eerstens, die kurwe van druk teenoor vloei is waarskynlik styler tydens eenlongnarkose. Hierdie is omdat pulmonale vaskulêre werwing en verwyding (pulmonale vaskulêre reserwe) is meer beperk as nornaal in pasiënte met longsiekte. Hierdie is die waarskynlikste rede hoekom pulmonale arterie druk tydens eenlongnarkose verhoog. Die redes hoekom die pulmonale vaskulêre reserwe in die onderste long tydens eenlongnarkose beperk is sluit in die volgende: 1.1 Die pulmonale vaskulêre bed van pasiënte onderwerp aan eenlongnarkose mag abnormaal wees weens die onderliggende long patologie, 1.2 Tydens eenlongnarkose in die laterale decubitus posisie, is long volume in hoë mate verminder as tydens tweelongnarkose, 1.3 Die voorafgenoemde vermindering in longvolume sal verder verminder word deur wanposisies van die dubbellumenbuis, sekresies en bloed, en absorpsie atelektase. 1.4 Te hoë vlakke van PEEP, oftewel intrinsiek of ekstrensiek van oorsprong, sal die intraalveolêre vate toedruk en so die pulmonale vaskulêre weerstand verhoog. 2. Tweedens, is daar groter vloei deur hierdie vaskulêre bed wat ‘n hoër weerstand bevat. Dit is opmerkingswaardig dat die verhoging in gemene pulmonale arterie druk ‘n waarde van 25 mmHg nie oorskry het nie tydens eenlongnarkose, alhoewel kardiale omset met 30% verhoog het. In pasiënte met beskadigde longe, het vorige studies egter bewys dat groter verhoging in PA druk gebeur tydens afbinding van die pulmonale arterie. Die vraag ontstaan dus hoekom daar verskille bestaan tussen wat gebeur tydens afbind van die pulmonale arterie en eenlongnarkose? Die antwoord mag wees dat die beperking in die styging in PA druk tydens eenlongnarkose as gevolg van ‘n progressiewe afleiding van bloedvloei na die nie-geventileerde long gebeur sodra pulmonale arterie druk styg tydens eenlongnarkose. Die implikasie van die afleiding van bloed na die nie geventileerde long is dat dit as ‘n veiligheids meganisme optree en verdere styging in pulmonale arterie druk beperk tydens eenlongnarkose. Hierdie afblaas meganisme sal die regter ventrikel beskerm tot en met PA afbind.Kontrole groep: eenlongnarkose en regter ventrikulêre funksie Die huidige studie bied die geleentheid om die betekenis van die voorafgenoemde verhoging in PA drukke en elastansie op regter ventrikulêre funksie tydens eenlongnarkose te ondersoek. Die huidige studie dui aan dat die 30% verhoging in pulmonale arterie druk wat met die aanvang van eenlongnarkose plaasvind, glad nie regter ventrikulêre funksie belemmer nie indien dit vergelyk word met die basislyn wakker staat. In teendeel, kardiale omset het verhoog na chirurgiese insnyding: hierdie verhoging is waarskynlik te wyte aan simpatiese senuwee stimulasie na die chirurgiese insnyding. Hierdie waarnemings pas in ook met ander studies waartydens regter ventrikulêre ejeksie alleenlik begin om af te neem indien die indekse van opposisie tot regter ventrikulêre ejeksie 200 tot 250% van basislyn bereik. Verder, die induksie van voorlading, naamlik sentrale veneuse druk, pulmonale arterie wigdruk en regter ventrikulêre einddiastoliese volumes is onveranderd tydens die huidige studie; dit beteken die ventrikel het nie gedilateer het nie tydens die verhoging in regter ventrikulêre nalading. Die verband tussen slagwerk en nalading sal varieer, afhanklik van die kontraktiele status van die ventrikel. In hierdie opsig, kon ons aflei dat die regter ventrikel, onder omstandighede wat tydens diė studie plaasgevind het, gefunksioneer het op die stygende been van die verband tussen regter ventrikulêre slagwerk en pulmonale arterie elastansie. Hierdie waarneming ondersteun die argument in die vorige paragraaf dat die regter ventrikel funksie behoue is tydens eenlongnarkose. Ter opsomming omtrent die indekse van opposisie tot pulmonale vloei en regter ventrikulêre funksie tydens eenlongnarkose: 1. Opposisie tot regter ventrikulêre uitwerp verhoog. Die bewys hiervoor is ’n 30% verhoging in gemene pulmonale arterie druk en ’n 36% verhoging in pulmonale arterie elastansie. 2. Ten spyte van die verhoging in weerstand teen RV uitwerping, het regter ventrikulêre funksie (soos bepaal deur regter ventrikulêre slagwerk indeks, regter ventrikulêre ejeksie fraksie en slag volume), nie verminder tydens eenlongnarkose in vergelyking met die waardes verkry wanneer die pasiënte wakker is of aan tweelongnarkose onderwerp is. 3. Ons kon ook aflei dat die koppeling tussen die regter ventrikel en sy lading goed behoue is tydens eenlongnarkose. Die implikasie hiervan is dat regter ventrikulêre slagwerk reserwe teenwoordig is tydens eenlongnarkose. Tydens eenlongnarkose funksioneer die regter ventrikel as ’n vloeipomp, net soos in normale lewe; dit beteken dat en die klein verhoging in regter ventrikulêre nalading wat ondervind word tydens eenlongnarkose maklik getolereer word. Dobutamien tydens eenlongnarkose: opposisie tot pulmonale vloei en regter ventrikulêre funksie Die uitwerking van dobutamien op regter ventrikulêre funksie tydens eenlongnarkose kan as volg opgesom word: 1. Lae dosisse dobutamien (3 μg.kg-1.min-1) verhoog kardiale omset, slagvolume en regter ventrikulêre slagwerkindeks. Die toediening van dobutamien 3 μg.kg-1.min-1 het nie saamgegaan met ‘n verhoging in regter ventrikulêre nalading nie. Dus, lae dosisse van dobutamien het wel die koppeling tussen die regter ventrikel en die pulmonale vaskulatuur tydens eenlongnarkose verbeter.2. Nietemin, albei die hoër dosisse van dobutamien (5 en 7 μg.kg-1.min-1) tydens eenlongnarkose het verhogings in die opposisie tot pulmonale bloedvloei teweeggebring. Byvoorbeeld, PA elastansie, gemene PA druk en pulmonale vaskulêre weerstand het met 30 tot 40% verhoog in vergelyking met die waardes gekry toe die pasiënte wakker was en toe albei longe geventileer is. ’n Belangrike opmerking in hierdie opsig is dat pulmonale arterie vervormbaarheid tydens eenlongnarkose met 61% verminder het tydens albei dobutamien 5 en 7 μg.kg-1.min-1. Die verhogings in gemene pulmonale arterie druk en pulmonale vaskulêre weerstand is, volgens mening, nie van kliniese of statistiese betekenis nie, alhoewel die vermindering in PA vervormbaarheid tydens die dobutamien 7 μg.kg-1.min-1 infusie wel van kliniese betekenis is. PA vervormbaarheid weerspieël een van die faktore wat vaskulêre impedansie in die 3- element Windkessel model van sirkulasie het. Die verhoging in opposisie tot pulmonale vloei en die afwesigheid van progressiewe verhogings in indekse van regter ventrikulêre funksie is nie wat verwag word indien die dosisse van die inotroop en pulmonale vasodilator dobutamien, progressief verhoog word. Die redes hoekom die opposisie tot pulmonale vloei verhoog tydens die toediening van dobutamien sluit in die uitwissing van die pulmonale vaskulêre reserwe tydens eenlongnarkose. Tydens die hoë kardiale indekse van 5 tot 5.5 μg.kg-1.min-1. is die pulmonale vaskulêre reserwe uitgeput en die meganisme het die verwagte pulmonale vaskulêre vasodilatasie van dobutamien oorskadu. Bowendien is dit waarskynlik dat die verhoging in regter ventrikulêre nalading betekenisvol genoeg was om te verhoed dat regter ventrikulêre funksie progressief verhoog soos sou verwag word met die administrasie van hoër dosisse inotroop. Die administrasie van dobutamien tydens eenlongnarkose het gemene pulmonale arterie druk verhoog tot ’n maksimum van 24,9 ± 6.2 mm Hg teen ’n kardiale indeks van 5.5 ± 1.2 l.min-1.m2. Nietemin is gemene pulmonale arterie druk 24.0 ± 7.7 mm Hg teen die maksimum kardiale indeks in die kontrole groep van 4.4 ± 1.1 l.min-1.m-2 tydens eenlongnarkose in die kontrole groep. Hierdie weerspieël dus ’n relatief beperkte verhoging in pulmonale arterie druk in vergelyking met die verhoging in pulmonale arterie druk wat gebeur het tydens die administrasie van dobutamien. Die waarskynlikste rede hoekom daar ’n beperkte verhoging in pulmonale arterie druk sou gewees het tydens die infusie van dobutamien is die afblaas effek van die nie-geventileerde long wat die verhoging in PA druk beperk het. Oksigenasie tydens eenlongnarkose Die volgende waarnemings is gemaak in verband met suurstof vloed, veneuse en arteriële oksigenasie tydens eenlongnarkose in die kontrole groep: 1. Die kombinasie van Induksie van narkose en die 1ºC vermindering in temperatuur het saamgegaan met ’n 40% vermindering in suurstof verbruik tydens twee long narkose. Hierdie vermindering in suurstof verbruik het voortgegaan tydens eenlongnarkose. 2. Die aanvang van eenlongnarkose is geassosieerd met ’n verhoging in kardiale omset in vergelyking met albei die basislyn eenlongnarkose en wakker state. 3. Die gevolge van punte 1 en 2 hierbo is dat die gemengde veneuse suurstof saturasie vanaf 75% en die gemeng veneuse suurstof spanning vanaf 5.4 kPa (toe die pasiënte wakker was) gestyg het tydens4. Tydens eenlongnarkose het die betekenisvolle verhoging in veneuse oksigenasie veroorsaak dat daar ’n verhoging in arteriële oksigenasie was in vergelyking met wanneer die pasiënte wakker was. Hierdie styging in arteriele oksigenasie was ten spyte van die 37% aftakking wat teenwoordig was tydens eenlongnarkose. 5. Onder toestande in die huidige studie, het dobutamien tydens eenlongnarkose nog arteriële nog veneuse oksigenasie verbeter nie, maar die arteriele oksigenasie het konstant gebly. ’n Belangrike observasie wat daarmee saamgaan is dat dobutamien toediening nie met ’n daling in arteriële suurstof spanning geassosieer is nie. Vervolgens, die hipotese dat die verhoging in kardiale omset geassosieer met dobutamien toediening tydens eenlongnarkose ’n verhoging in arteriële oksigenasie beweeg bring, is dus verwerp. Die verwerping van die hipotese van die deel van die studie beteken dat die bevindinge die teenoorgestelde is van die studies gepubliseer deur Mathru en sy kollegas en Nomoto en Kawamura. Hierdie outeurs het gedemonstreer dat die toediening van inotrope ’n verhoging in arteriële oksigenasie teweeg gebring het. Nietemin is die teenoorgestelde gevolgtrekkinge nie teenstrydig met mekaar nie. Inteendeel hierdie verskille help ons om die effek van ’n verhoging in kardiale omset of arteriële oksigenasie in die teenwoordigheid van ’n betekenisvolle aftakking duidelik te maak. Die verskille tussen die studies kan op die volgende manier verduidelik word. Toestande wat in die huidige studie teenwoordig was het veroorsaak dat die verband tussen suurstof lewering en verbruik baie hoog was en dat die gemeng veneuse suurstof spanning baie hoog was om mee te begin alvorens dobutamien geinfuseer is. Dus is die veneuse saturasies op die plat deel van albei die suurstof dissosiasie kurwe en ook van die verband tussen kardiale omset en arteriële suurstof inhoud oorspronklik deur Kelman, Nunn en kollegas beskryf. Verdere verhogings in kardiale omset sou dus nie verwag word, en het nie, verhogings in gemeng veneuse suurstof spanning, gemeng veneuse suurstof saturasie of gemeng veneuse suurstof inhoud teweeg gebring. Dus, arteriële suurstof inhoud en saturasie het nie verander na die verhoging in kardiale omset wat teweeg gebring is deur die toediening van dobutamien in die huidige studie. Inteendeel, in die studie deur Mathru en kollegas, is die lae aanvanklike veneuse saturasie en spanning verbeter deur verhogings in die verband tussen suurstoflewering en suurstofverbruik. Omdat die veneuse saturasie aan die begin van die Mathru studie laag was, is betekenisvolle voordeel in arterieël oksigenasie teweeg gebring deur om die kardiale omset te verhoog. ’n Groot bekommernis vir die klinikus is dat die aftakking mag verhoog met die toediening van die inotroop dobutamien tydens eenlongnarkose en, op die manier, arteriële oksigenasie mag verminder. Die invloed van dobutamien op arteriële oksigenasie tydens eenlongnarkose mag teoreties te wyte wees aan die balans van die volgende uiteenlopende faktore: 1. Deur om die verband tussen suurstof lewering en verbruik te verbeter, sal dobutamien gemeng veneuse suurstof spanning verhoog. Hierdie verhoging sal arteriële oksigenasie verbeter in die teenwoordigheid van ’n groot aftakking, 2. Die bogenoemde moet teenoor potensiële verhogings in suurstofverbruik deur dobutamien oorweeg word. Die gevolge hiervan sou potensieel ’n vermindering in gemeng veneuse suurstof spanning wees. Sulke verhogings in suurstof verbruik is nie tydens die huidige studie gesien nie,3. ’n Verhoging in pulmonale arterie druk wat saamgaan met die verhoogde kardiale omset sal hipoksiese pulmonale vasokonstriksie teenwerk wat die aftakking in albei die geventileerde en nie geventileerde longe sal verhoog, 4. Direkte inhibisie van hipoksiese pulmonale vasokonstriksie deur dobutamien en, 5. Die invloed van gemeng veneuse suurstof spanning op hipoksiese pulmonale vasokonstriksie moet ook oorweeg word (d.i. hoe gemeng veneuse suurstof parsiele druk sal hipoksiese pulmonale vasokonstriksie inhibeer). Nietemin, ten spyte van die bekommernisse rondom hipoksemie tydens die toediening van dobutamien tydens eenlongnarkose, het dobutamien toediening nie ’n verlaging in arteriële suurstof spanning teweeg gebring nie, en ook het dit nie die koste van oksigenasie verhoog nie. Verder, die bevindinge van studies tydens eenlongnarkose in die laterale decubitus posisie deur Mathru en sy kollegas, Nomota en Kawamura en ook die huidige studie, dui aan dat die toediening van lae dosisse van dobutamien nie toe ’n verhoging in aftakking lei nie. Inteendeel, die voordelige effekte van die verhoging in kardiale omset op veneuse saturasie het veroorsaak dat daar ’n verhoging in arteriële saturasie is in die studie deur Mathru en sy kollegas soortgelyke meganismes is waarskynlik ook van toepassing in die studie wat gedoen is deur Nomoto en Kawamura. Dus, dwars deur die literatuur, is daar geen huidiglike bewys dat die toediening van dobutamien tot en met dosisse van 7μg.kg-1.min-1 aftakking verhoog of arteriële oksigenasie versleg in mense onderworpe aan eenlongnarkose in die laterale decubitus posisie. Dit is duidelik dat die vasodilatoriese effekte van dobutamien wat moontlik ’n verhoging in aftakking fraksie teweeg kan bring, nie die enigste faktore is om te oorweeg wanneer die middel se invloed op arteriële oksigenasie bestudeer word nie. Dit is ook van kliniese belang om die invloed van inotrope middels op veneuse suurstof inhoud te oorweeg. Dit is moontlik dat ’n aftakking verhoog kan word deur die toediening van ’n inotroop. Nietemin, mag die negatiewe effek wat die toediening van ’n inotroop sal inhou op arteriële oksigenasie deur middel van sy verhoging in aftakking, negeer word indien veneuse oksigenasie voordelig beïnvloed is. Verder, indien die verhoging in veneuse oksigenasie wat teweeggebring word deur die toediening van inotrope baie betekenisvol is, mag die gevolg hiervan wees dat arteriële oksigenasie voordelig beïnvloed word soos die geval in die huidige studie was. Die huidige benadering waar die kwaliteit van die bloed wat deur die aftakking vloei die arteriële oksigenasie beïnvloed, skuif die klem van voorkoming en behandeling van hipoksemie tydens eenlongnarkose van die long na die toereikendheid van die sirkulasie. Met ander woorde, die klem is geskuif van wat gebeur in die nie-geventileerde long (hipoksie pulmonale vasokonstriksie) tot primêr die toereikendheid van suurstof flux tydens eenlongnarkose. Ekstrinsieke en intrinsieke PEEP tydens eenlongnarkose Die invloed van PEEP op hemodinamika en oksigenasie tydens eenlongnarkose in die huidige studie mag as volg opgesom word. Toe PEEP5 tydens eenlongnarkose toegedien is: 1. Nie regter ventrikulêre funksie, hemodinamika, suurstof flux nog arteriële oksigenasie is beïnvloed deur die toediening van PEEP5 in vergelyking met die stap wanneer geen eksterne PEEP toegedien is nie. 2. Betekenisvolle hoeveelhede intrinsieke PEEP is teenwoordig tydens eenlongnarkose in die kontrole groep.Die hoeveelheid intrinsieke PEEP wat teenwoordig was, is swak maar betekenisvol verwant aan die graad obstruktiewe lugwegsiekte wat teenwoordig was gemeet deur pre-operatiewe longfunksie toetse. 3. Die waarskynlikste rede hoekom PEEP5 nie ’n verskil gemaak het aan oksigenasie of hemodinamika nie is die teenwoordigheid van soortgelyke hoeveelhede intrinsieke PEEP tydens eenlongnarkose. Hierdie bevinding bevestig Myle’s se beweringe dat lae vlakke intrinsieke PEEP voordelige effekte op oksigenasie tydens eenlongnarkose mag hê. PEEP10 toediening aan die onderlong tydens eenlongnarkose in die huidige studie het tot ’n vermindering in slagvolume gelei. Hierdie vermindering is primêr veroorsaak deur ’n vermindering in voorlading en nie die gevolg van ’n verhoging in pulmonale vaskulêre weerstand nie. Die gevolgtrekking is gemaak omdat regerventrikulere enddiastoliese volume verlaag het maar pulmonale vaskulêre weerstand het nie verhoog tot vlakke wat bekend is om regter ventrikulêre funksie te belemmer nie. Die vermindering in die verhouding tussen suurstof lewering en suurstof verbruik wat geïnduseer is deur PEEP10 het (voorspelbaar) gemeng veneuse suurstof spanning verminder en kon potensieël gelei het tot belemmering in arteriële oksigenasie. Indien minder voordelige sirkulatoriese toestande geheers het tydens die huidige studie, sou groter (oorbodige) hoeveelhede PEEP slegter kardiorespiratoriese gevolge tot gevolg gehad het. Ter opsomming, optimalisering van die volume van die onderlong tydens eenlongnarkose speel ’n belangrike rol in die bepaling van arteriële oksigenasie. Nietemin, die terapeutiese indeks vir PEEP is nou en die narkotiseur het die behoefte om te weet wanneer die volume van die onderlong optimaal is. In die opsig, is ’n betekenisvolle probleem tydens eenlongnarkose dat meting van funksionele residuele kapasiteit nie huidiglik maklik is nie

Abstract Antioxidants function as blockers of radical processes and eliminate harmful reactive oxygen species (ROS) produced during normal cellular metabolism. A complex antioxidant defence system has evolved to protect the cellular homeostasis. This system includes antioxidant enzymes (AOEs), such as superoxide dismutases (SODs), which are intracellular MnSOD and CuZnSOD and extracellular ECSOD, H2O2 scavenging enzymes catalase and glutathione peroxidase, and hemeoxygenase-1 (HO-1), an important enzyme in heme metabolism, which has also been suggested to have antioxidant capacities. ROS play an important role in the pathogenesis of interstitial lung diseases. These diseases represent a group of disorders with different etiology, histopathology, treatment and prognosis. Sarcoidosis, extrinsic allergic alveolitis and two different forms of idiopathic pulmonary fibrosis, usual interstitial pneumonia (UIP) and desquamative interstitial pneumonia (DIP) were included in this study. The purpose of this research was to evaluate the expressions of inducible nitric oxide synthase (i-NOS), endothelial nitric oxide synthase (e-NOS) and xanthine oxidase (XAO), oxidant generating enzymes commonly associated with tissue injury, and, on the other hand, the expressions of AOEs suggested to be involved in the defence of lung tissue against oxidant stress. The methods included immunohistochemistry on lung biopsies (n=48) and Western blotting, Northern blotting or reverse polymerase chain reaction (RT-PCR) on human inflammatory cells and cells obtained from bronchoalveolar lavage. I-NOS was intensively expressed in inflammatory, but not in fibrotic lesions, similar e-NOS expression was found in control lung and in all interstitial lung diseases, while XAO was mainly negative. MnSOD and HO-1 were highly expressed in the granulomas of sarcoidosis. In contrast the expressions of MnSOD and HO-1 in late fibrotic lesions of UIP were low or undetectable by immunohistochemistry. CuZnSOD and catalase showed similar immunoreactivity in healthy and diseased lung. A cell specific expression and regulation of various enzymes may play an important role during acute inflammatory diseases and also in the progression of lung fibrogenesis.

Cellular senescence, the irreversible loss of replicati ve capacity of somatic cells, bas been associated w ith diseases of accelerated lung ageing, including Chroni c Obstructive Pulmonaty Disease (COPD). However, the mechanisms und erl ying senescence of a irway epithelial cell s, parti cula rl y the role of telomere dysfunction in this process, are poorly understood . The aim of this work was to investigate senescence and telomere dysfunction in airway epithelial cells from pati ents with COPD and bronchiectasis, in the ageing murine lung and in the context of cigarette smoke exposure. DNA dam age foci (yH2A.X) and foci associated with telomeres (telomere-associated foci (TA F)), a long with other senescence-associated m arkers, were increased in small airway epith elial cells from patients with COPD, wi thout significant telomere shottening. With age, TAF increased in large and sm all aitway epithelial cells of the murine lung and predicted age-dependent lung emphysema, independen tly oftelomere length . M oreover, fomth generation telomerase-null mi ce showed early-onset emphysema. Exposure to cigarette smoke was found to increase TAF in large and small ai1way epithelial cells of the murine lung and in epith elial cells and fibrobla sts in vitro. Cigarette smoke m ay accelerate telomere dysfunction via reactive oxygen species (ROS) and contribute to Ataxia telangiectasia mutated (ATM)-dependent secretion of pro-inflammatory cytokines interleukin (lL)-6 and IL-8. Inhibition of mechan istic target of rapa myc in complex I (mTORC I ) by rapa mycin alleviated age-assoc iated increases i n TAF in vivo and supressed cigarette smoke-i nduced increases in TAF and in flammatory cytokine release in vitro. Cigarette smoke increases mitochondrial-derived ROS, which is supressed by culturing cell s at low oxygen pressure and by treating cell s w ith rapam ycin. These results suggest that activation of a DN A damage response at telomeres may be induced by oxidative stress from altered mTOR signalling ancl/or dysfu nctional mitochondri a. Telomere dys function could conttibut e to inflamm atory processes and the functional decline that occurs in the ageing lung and in the context of cigarette smoke­ induced accelerated lung ageing.

Il carcinoma polmonare non a piccole cellule (NSCLC) rappresenta circa l 80% di tutti i tumori al polmone ed è il cancro più comune e più mortale al mondo. Il trattamento convenzionale per il NSCLC in stadio avanzato è stato basato per molto tempo sull uso della chemioterapia, ma con basso impatto sulla sopravvivenza . Una migliore comprensione dei meccanismi molecolari coinvolti nel processo di tumorigenesi e una maggiore capacità nell identificazione di specifiche alterazioni genetiche come bersagli terapeutici, hanno portato ad un significativo avanzamento verso lo sviluppo di terapie più efficaci. Il recettore del fattore di crescita dell epidermide (EGFR) è spesso over-espresso nel NSCLC ed è considerato un promettente bersaglio terapeutico per il trattamento di questo tumore. La presenza di mutazioni nel gene EGFR sono un importante predittore di risposta agli inibitori dell EGFR. Sebbene gli inibitori dell EGFR di prima generazione hanno mostrato incoraggianti risposte cliniche nei tumori al polmone, quasi tutti i pazienti sviluppano resistenza al trattamento nel corso del tempo. La resistenza ai trattamenti potrebbe dipendere anche dalla presenza delle cellule staminali tumorali (CSCs), una sottopopolazione di cellule intrinsecamente resistenti. Così, lo studio delle cellule staminali tumorali del polmone, potrebbe essere uno strumento efficace per l identificazione e validazione di bersagli terapeutici innovativi contribuendo all'introduzione di importanti miglioramenti nell ambito dell oncologia clinica. Pertanto, la terapia mirata verso l EGFR continua ad evolvere in seguito alla scoperta della sensibilità agli inibitori tirosin-chinasici da parte di pazienti caratterizzati da mutazioni attivanti del gene EGFR. Tuttavia, circa il 10-20% dei pazienti privi della mutazione dell EGFR, beneficiano anch essi del trattamento con gli inibitori TKIs, suggerendo che potrebbero esistere altri determinanti di risposta al trattamento, indipendenti dalla mutazione del recettore. Questo progetto, quindi, è stato focalizzato sull analisi della via di segnale dell EGFR e sullo studio della sensibilità delle cellule staminali tumorali di polmone e di modelli murini da esse derivati, agli inibitori dell EGFR, al fine di identificare possibili biomarcatori predittivi di risposta agli TKIs, in cellule prive della mutazione dell EGFR. Questo studio ha portato all identificazione della fosforilazione dell EGFR al residuo tirosina 1068, ma non 1173, come potenziale marcatore di risposta all Erlotinib nelle cellule staminali tumorali di polmone e negli xenografts da esse derivati. Inoltre, anche linee cellulari commerciali di polmone sensibili all Erlotinib, esprimevano pEGFR-tyr-1068 indipendentemente dalla mutazione dell EGFR, così, l espressione di pEGFR-tyr1068 nelle cellule staminali tumorali di polmone è risultata essere associata ad una risposta positiva al trattamento con l Erlotinib. La valutazione, mediante immunoistochimica, dello stato di fosforilazione dell EGFR in pazienti con mutazione e senza mutazione del recettore, ha portato a correlare solo pEGFR-tyr1068 e non pEGFR-tyr1173, con la mutazione dell EGFR. In base a questi dati, quindi, è possibile ipotizzare che l identificazione del livello di fosforilazione dell EGFR al residuo tirosina 1068 nei tumori dei pazienti, permetterebbe di individuare tumori con e senza mutazione dell EGFR ma caratterizzati da attivazione del recettore, in grado probabilmente di rispondere in modo positivo al trattamento con l Erlotinib. Questi studi potrebbero avere importanti implicazioni terapeutiche per il trattamento dei tumori al polmone e potrebbero permettere ai pazienti con NSCLC di essere selezionati per terapie più efficaci e meno tossiche.

2014 - 2015
Lung cancer is recognized as one of the most devastating tumor worldwide due to the low rate survival over 5 years from the time of diagnosis. Inflammation has been widely recognized as the seventh hallmark of cancer as it facilitates the establishment/development and progression of lung cancer. In this context, recent evidence highlighted the role of the inflammasome during carcinogenesis. However, little is still known. The inflammasome is a multiprotein complex that leads to caspase-1 activation which role in lung cancer is still under investigated. In this context, the aim of my PhD project was to understand the role of the inflammasome in lung cancer in a mouse model of carcinogen-induced lung cancer and in human non-small cell lung cancer (NSCLC). We found that both caspase-1-dependent, the canonical pathway, and caspase-8/caspase-11-dependent, the non-canonical pathway, inflammasome were involved during lung cancer establishment and progression in both mice and humans. Our data showed that the pharmacological inhibition of both caspase-1 and caspase-8 significantly reduced lung tumor outgrowth associated to lower pro-inflammatory response and to a reduced lung recruitment of immunesuppressive cells and that caspase-8 was upstream caspase-1 activation during lung carcinogenesis. Furthermore, we showed that caspase-11 was the primary/main orchestrator of the inflammasome-dependent lung cancer progression and that the enzyme could be upstream of caspase-1 to induce the amplification of the occurring inflammatory process associated to lung cancer development. Finally, we identified a novel mechanism by which lung tumor-associated macrophages could favor lung tumorigenesis via the activation of caspase-11-dependent inflammasome and the consequent release of the pro-tumorigenic IL-1α. [edited by author]
XIV n.s.

This study examined the effects of epinephrine, norepinephrine, AVP and ACh on fluid movement by the lungs of the late-term guinea pig fetus. Catecholamines and AVP are secreted in high amounts by the fetus during delivery, and could be important with respect to fetal lung fluid removal; this event is vital at the time of birth. The lungs were supported in vitro for a duration of three hours, and production rates were measured using a dye-dilution technique. The average resting production rate in terms of ml/kg‧h declined with gestational age (54-67 days gestation; n=171). There was a lesser decline in the average resting production rate in terms of ml/h. The average production rate of untreated preparations in the first hour was 1.60 ± 0.26 ml/kg body weight per hour, and rates did not change significantly during the remaining two hours of experimentation (n=30). This rate is comparable to those reported from chronically catheterized fetal sheep. Treatment was administered during the second hour of experimentation, following an ABA design. Lungs (n=36) were transferred to fresh Krebs-Henseleit saline containing one of the following concentrations of epinephrine: (a) 10‾⁵ M; (b) 10‾⁶ M; (c) 10‾⁷ M; (d) 5 x 10‾⁸ M; (e) 10‾⁸ M; and (f) 10‾⁹ M. With the exception of the top dose, epinephrine treatment caused an immediate reduction in fluid secretion, or fluid reabsorption. Sodium followed the movement of water in all cases. The effect of epinephrine at 10‾⁷ M was maximal, and the threshold dose for epinephrine was calculated at 1.78 x 10‾¹¹ M. Phentolamine and propranolol had no effect in control preparations. However, phentolamine completely blocked the effect of epinephrine, whereas propranolol was ineffective. Isoproterenol had no effect on pulmonary fluid production. Alpha-adrenergic receptors apparently mediate the effect of epinephrine on pulmonary fluid movement in the fetal guinea pig lung. This conclusion is different from that obtained in fetal sheep, in which beta-adrenergic receptors are utilized. A possible synergism between epinephrine and AVP was examined. Lungs (n=12) were transferred to fresh Krebs-Henseleit saline containing either (a) 0.6 mU/ml AVP, or b) 0.6 mU/ml AVP combined with epinephrine at 10‾⁷ M. Treatment with AVP caused a slow, prolonged reduction in fluid production. Treatment with AVP together with epinephrine did not demonstrate synergism. The effect of norepinephrine (NE) was examined. Lungs (n=36) were transferred to fresh Krebs-Henseleit saline containing one of the following concentrations of NE: (a) 1.24 x 10‾⁵ M; (b) 1.24 x 10‾⁶ M; (c) 1.24 x 10‾⁷ M; (d) 5.24 x 10‾⁸ M; (e) 1.24 x 10‾⁸ M; and (f) 1.24 x 10‾⁹ M. In all preparations, treatment with NE resulted in an immediate reduction in fluid production, and reabsorptions were observed at the higher doses. Sodium followed the movement of water in every case. The threshold dose was calculated at 3.16 x 10‾¹⁰ M. Phentolamine blocked the effect of NE, reinforcing the importance of pulmonary alpha-adrenergic receptors in the fetal guinea pig. There was no relationship between age and degree of response with treatment of either epinephrine or NE, but fetuses under 78.0 g did not respond to NE. The effect of ACh was examined. Lungs (n=24) were transferred to fresh Krebs-Henseleit saline containing one of the following concentrations of ACh: (a) 10‾⁴ M; (b) 10‾⁵ M; (c) 10‾⁶ M; and (d) 10‾⁸ M. At the three top doses, immediate and powerful reabsorptions of pulmonary fluid were observed in older fetuses (60 days gestation and above); significant falls were observed in the younger fetuses. This result was unexpected, as it was hypothesized that ACh would stimulate fluid production. The threshold dose for ACh was between 10‾⁶ M and 10‾⁸ M. Phentolamine blocked the effect of ACh. This result suggested that reabsorption is a result of an indirect effect of ACh acting through pulmonary alpha receptors. The results in this study show that epinephrine, NE, AVP and ACh are all important promoters of fetal pulmonary fluid removal in the fetal guinea pig. Pulmonary alpha-adrenergic receptors mediate the effects of epinephrine, NE and ACh (indirectly). The conclusions drawn from this study emphasize the importance of species' comparison in fetal research. LIST OF ABBREVIATIONS AVP Arginine Vasopressin NE Norepinephrine DOPA dihydroxyphenylalanine PNMT Phenylethanolamine n-methyltransferase ACh Acetylcholine
Science, Faculty of
Zoology, Department of
Graduate

Thesis (M. Eng.)--Harvard-MIT Division of Health Sciences and Technology, 2004.
Includes bibliographical references (p. 76-77).
The focus of this study was to investigate the histology of tissue formed when fetal (16-20 days gestation) and neonatal (2 days old) rat lung cells were grown in a collagen-glycosaminoglycan scaffold. This project employed a collagen-GAG scaffold specifically developed for tissue engineering and investigated the effect of this substratum on the formation of lung histotypic structures in vitro. A cell isolation procedure was developed whereby 19-days gestation type II alveolar cells reaggregated to form alveolar-like structures. The effects of selected scaffold design variables including pore diameter and degradation rate of the substratum on lung tissue regeneration were explored. Lung cell behavior revealed as the cells interact with an analog of the extracellular matrix was also examined. Differences in fetal and neonatal lung cell behavior were identified using histological analysis. Lung cells were obtained from Sprague-Dawley rats after 16-, 19-, and 20-days of gestation and at 2 days after term. These cells were seeded into type I collagen-GAG matrices, sized 8mm in diameter by 2mm in thickness. The medium used, F12K and Ham's nutrient mixture, was supplemented with 10% fetal bovine serum. A seeding density between 1 to 5 million cells per sponge sample was used. Histology studies were performed at termination periods of 2, 14, and 28 days. This paper describes the in vitro formation and long-term maintenance of alveolar-like structures from enzymatically dissociated 19-days gestation fetal rat lung cells cultured on a collagen sponge substrate as a model system for lung tissue engineering.
by Patty P. Chen.
M.Eng.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2003.
Includes bibliographical references.
Lung cancer is the leading cause of cancer deaths worldwide. Patients are typically diagnosed with advanced disease and have a high fatality:case ratio. Despite its prevalence, the identity of the cell of origin, precursor lesions and stages of disease progression have not been well characterized for most types of lung cancer. Furthermore, there are no effective screening methods for lung cancer and standard chemotherapeutics are ineffective in treating advanced lung cancer. The work presented here describes the development and characterization of a murine lung cancer model that uses conditional expression of oncogenic K-ras to drive tumorigenesis. The conditional allele is controlled by the Cre-loxP system. Using adenovirus to deliver Cre recombinase to the lungs we have controlled the timing and multiplicity of tumor initiation. We used this model to investigate several aspects of tumor biology. Timecourse experiments revealed the histologic stages of lung tumor progression, advancing from atypical adenomatous hyperplasia to adenoma to adenocarcinoma. Studies of early lesions provided insights into the ras effector pathways required for tumor initiation, implicating the JNK and p38 pathways in this process. In addition, our studies regarding the cell of origin of lung tumors led to the identification of a novel cell type in the adult lung that resembles an embryonic lung precursor cell.
(cont.) A common feature of mouse tumor models is that they mainly resemble the early stages of tumor development. In an effort to create a model representing advanced disease, we generated K-rasG12D;p53 compound mutant mice with varyious combinations of different conditional mutant p53 alleles. The compound mutant mice develop lung tumors that recapitulate several aspects of advanced human disease including stromal desmoplasia, invasion and metastasis. Missense mutation is the most common form of p53 mutation in human tumors, suggesting that the mutant p53 protein may confer a selective advantage on the tumor cells during tumorigenesis. Our comparison of the oncogenic effects of p53R172H, p53R270H and a conditional null allele, p53Fl, revealed that the p53R270H mutation results in a dominant negative allele. Furthermore, our studies revealed an oncogenic gain-of-function effect of both p53R172H and p53R270H on the development of nasopharyngeal carcinomas.
by Erica L. Jackson.
Ph.D.

Acute lung injury (ALI) is a severe inflammatory lung disease with high mortality. Previous studies revealed several important concepts in ALI, including cellular interaction between lung-marginated leukocytes and pulmonary endothelium, and decompartmentalisation of soluble mediators. However, there are inherent limitations within both in vivo and in vitro models to identify the detailed mechanism underlying these concepts. In this PhD project, we attempted to address these unanswered questions, using an in situ isolated perfused mouse lung (IPL). Specifically, we aimed to 1) develop, characterise, and optimise the mouse IPL model; 2) investigate soluble and cellular aspects of two models of ALI that are particularly amenable to study using the IPL, namely ventilator-induced lung injury (VILI) and ischaemia-reperfusion injury. From a physiological viewpoint, VILI consists of 2 primary components, high-stretch and atelectasis. Modelling atelectasis-related injury in vivo is difficult due to negative pleural pressure. We took advantage of the zero pleural pressure of open-chest IPL system to develop an atelectasis-related VILI model. Comparison of this ‘atelectrauma’ and a high-stretch ‘volutrauma’ model demonstrated that both cause lung oedema and pulmonary inflammation, but the inflammatory impact was different between them. Volutrauma, but not atelectrauma, facilitated systemic cytokine release, in which lung-marginated monocytes seem to play an important role. This finding in the VILI model drove us to further investigate the role of these monocytes in an ischaemia-reperfusion model, which is clinically highly relevant and simulates a lung transplantation setting. Our results suggested that lung-marginated monocytes may also contribute to develop ischaemia-reperfusion injury, potentially involving TNF upregulation. Through this PhD project, we have successfully developed a technically very challenging mouse IPL model. We utilised the unique features of the IPL to develop experimental models that we believe will be strong tools to fill the gap between in vivo physiological significance and in vitro mechanistic understanding.

We describe an online clinical decision support (CDS) system, Lung Cancer Assistant (LCA), which we have developed to aid the clinicians in arriving at informed treatment decisions for lung cancer patients at multidisciplinary team (MDT) meetings. LCA integrates rule-based and probabilistic decision support within a single platform. To our knowledge, this is the first time this has been achieved in the context of CDS in cancer care. Rule-based decision support is achieved by an original ontological guideline rule inference framework that operates on a domain-specific module of Systematized Nomenclature of Medicine-Clinical Terms (SNOMED-CT), containing clinical concepts and guideline rule knowledge elicited from the major national and international guideline publishers. It adopts a conventional argumentation-based decision model, whereby the decision options are listed along with arguments derived by matching the patient records to the guideline rule base. As an additional feature of this framework, when a new patient is entered, LCA displays the most similar patients to the one being viewed. Probabilistic inference is provided by a Bayesian Network (BN) whose structure and parameters have been learned based on the English Lung Cancer Database (LUCADA). This allows LCA to predict the probability of patient survival and lay out how the selection of different treatment plans would affect it. Based on a retrospective patient subset from LUCADA, we present empirical results on the treatment recommendations provided by both functionalities of LCA and discuss their strengths and weaknesses. Finally, we present preliminary work, which may allow utilising the BN to calculate survival odd ratios that could be translated into quantitative degrees of support for the guideline rule-based arguments. An online version of LCA is accessible on http://lca.eng.ox.ac.uk.

Bioengineering
Ph.D.
Decellularized lung tissue has been recognized as a potential platform to engineer whole lung organs suitable for transplantation or for modeling a variety of lung diseases. However many technical hurdles remain before this potential may be fully realized. Inability to efficiently re-endothelialize the pulmonary vasculature with a functional endothelium appears to be the primary cause of failure of recellularized lung scaffolds in early transplant studies. This dissertation research aims to enhance the re-endothelialization of decellularized rodent lung scaffolds with rat lung microvascular endothelial cells. This was achieved by adjusting the posture of the lung to a supine position during cell seeding through the pulmonary artery. The supine position allowed for significantly more homogeneous seeding and better cell retention in the apex regions of all lobes than the traditional upright position, especially in the right upper and left lobes. Additionally, the supine position allowed for greater cell retention within large diameter vessels (proximal – 100 µm to 5,000 µm) than the upright position, with little to no difference in the small diameter distal vessels. Endothelial cell adhesion in the proximal regions of the pulmonary vasculature in the decellularized lung was dependent on the binding of endothelial cell integrins, specifically α1β1, α2β1 and α5β1 integrins to, respectively, collagen type-I, type-IV and fibronectin in the residual ECM. Following in vitro maturation of the seeded constructs under perfusion culture, the seeded endothelial cells spread along the vascular wall, leading to a partial re-establishment of endothelial barrier function as inferred from a custom-designed leakage assay. The results of this dissertation research suggest that attention to cellular distribution within the whole organ is of paramount importance for restoring proper vascular function.
Temple University--Theses