by Tong Kwok-keung. / Year shown on spine: 1997 / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (p. [99]-[104]) / Acknowledgements --- p.i / Abstract --- p.ii / List of Tables --- p.vii / List of Figures --- p.viii / List of Abbreviations --- p.ix / Introduction --- p.1 / Background of Study --- p.1 / Statement of the Problem --- p.3 / Significance of Study --- p.7 / Review of Literature --- p.9 / Ventilatory Muscle Capacity - a Limiting Factor of Exercise Performance --- p.9 / Rib Cage Loading as a Respiratory load --- p.11 / Methods of Rib Cage Loading --- p.13 / The Physical Changes in Respiratory System during Rib Cage Loading --- p.14 / The Physiological Changes in Cardiorespiratory System during Rib Cage Loading --- p.17 / Mechanisms for the Changes in Ventilatory Muscle Activity andin Respiratory Response during Rib Cage Loading --- p.20 / Effects of Rib Cage Loading on Exercise Performance --- p.23 / Summary of Review --- p.25 / Methodology --- p.28 / Statement of Hypotheses --- p.28 / Operational Definitions of Variables --- p.28 / Subjects --- p.31 / Procedures --- p.31 / Instrumentation --- p.33 / Methods of Measurement --- p.36 / Assumptions --- p.50 / Data Analysis --- p.51 / Results --- p.53 / "Physical Characteristics, Forced Spirometry and Maximal Aerobic Power of Subjects" --- p.53 / Effects of Rib Cage Compression on Subdivisions of Lung Volume and Total Respiratory Elastance --- p.53 / Effects of Rib Cage Compression on Exercise Endurance --- p.56 / Effects of Rib Cage Compression on Ventilatory Muscle Function during the cycle exercise --- p.60 / Effects of Rib Cage Compression on Respiratory Response at Rest and during Exercise --- p.63 / Effects of Rib Cage Compression on Oxygen Consumption and Gas Exchange at Rest and during Exercise --- p.69 / Effects of Rib Cage Compression on Heart Rate and Arterial Blood Pressure at Rest and during Exercise --- p.73 / Discussion --- p.79 / The Physical Changes in Respiratory System during Rib Cage Compression --- p.79 / Reduction in Cycle Exercise Endurance with Rib Cage Compression --- p.81 / Conclusion --- p.94 / Implications --- p.95 / Delimitations and Limitations --- p.96 / Suggestions --- p.97 / Bibliography / Appendix I Informed Consent / Appendix II Cycling Protocol for Incremental Exercise Test / Appendix III Cycling Protocol for Cycle Exercise Endurance Test / Appendix IV / Figure IV-I. The changes in volume-pressure tracings with and without rib cage compression during measurement of total respiratory elastance / Table IV-I. The subdivisions of lung volume of each subject with and without rib cage compression / Table IV-II. The cycle exercise duration of each subject with and without rib cage compression / Table IV-III. The static maximum inspiratory and expiratory pressures of each subject before and after exercise during both cycle exercise tests / Table IV-IV. & IV-V. The means of each parameter of respiratory response during both cycle exercise tests / "Table IV-VI. The means of end-tidal C02 tension, arterial oxygen content and oxygen consumption during both cycle exercise tests" / "Table IV-VII. The means of heart rate, and systolic and diastolic blood pressures during both cycle exercise tests"

Le syndrome d’apnées obstructives du sommeil (SAOS) se caractérise par des collapsus récurrents des voies aériennes supérieures pendant le sommeil, entraînant des épisodes d’hypoxie/hypercapnie. Par ces variations gazeuses, le SAOS entraîne des altérations cardiorespiratoires, représentant ainsi un danger de vie pour les patients, mais dont certaines sont moins marquées chez les patientes. La prévalence chez les hommes est plus élevée que celle des femmes pré-ménopausées et elle est augmentée par l’obésité.L’objectif de ce doctorat était de caractériser les dimorphismes sexuels dans la neuroplasticité associée au SAOS, à l’origine des altérations cardiorespiratoires. Pour cela, nous avons soumis des souris à un protocole d’hypoxie intermittente chronique (HIC), ce modèle récapitulant l’hypoxie récurrente du SAOS. Dans l’encéphale de ces souris, nous avons pu apprécier des atteintes différentielles entre les souris mâles et femelles au sein de structures cardiorespiratoires avec un profil de neuroplasticité réservé aux femelles qui pourrait atténuer chez ces dernières les effets de l’HIC. Cela ouvre des pistes explicatives des différences sexuelles retrouvées chez les patients et patientes SAOS. Nous avons également caractérisé une souche de souris obèses (New Zealand Obese) en tant que modèle du SAOS. Nous fournissons ainsi le premier modèle murin naturel du SAOS lié à l’obésité. Enfin, ce travail contribue à une meilleure connaissance des différences sexuelles observées dans le SAOS et fournit un modèle facilement accessible qui offre la possibilité de réaliser des études plus complètes de la pathologie du SAOS. / The obstructive sleep apnea syndrome (OSAS) is characterized by recurrent collapse of the upper airways during sleep, generating episodes of hypoxia/hypercapnia. Thus, OSAS leads to life-threatening cardiorespiratory comorbidities, but of which some are less severe in female patients. The prevalence in men is higher than that of pre-menopausal women and it is increased by obesity. This doctoral thesis aimed to characterize sex differences in the neuroplasticity related to cardi-orespiratory comorbidities found in OSAS. In this context, we submitted mice to a protocol of chronic intermittent hypoxia, a model that recapitulates episodic hypoxia of OSAS. On isolated brain sections, we observed differential implication of cardiorespiratory structures between male and female mice with a specific neuroplastic pattern in females that could possibly explain sex differences observed in OSAS patients. In parallel, we have characterized an obese mouse strain (New Zealand Obese) as a model of OSAS. Thus, we provide the first naturel mouse model for OSAS related to obesity. The work presented in this thesis provides better understanding of sex differences observed in OSAS and provides a new model of OSAS that should allow more complete studies of the pathology of OSAS.

This study aims to understand the influence of hydrochemical and nutrient dynamics on the metabolism of organic carbon, and to explore the relationship between the metabolism of organic carbon and air-sea fluxes of CO2 in the Kaoping coastal zone and the northern South China Sea (NSCS). Distributions of nutrients in the Kaoping Canyon increased generally with the increase of freshwater input from the Kaoping River that discharged the highest rate during the summer season. In the northern SCS, the enhanced nutrient distributions were caused by freshwater input or upwelling in coastal and shelf zones, and by vertical mixing in the central basin in winter. During the study periods, the integrated gross production (IGP) ranged from 1389 to 8918 mgC m-2d-1 in the Kaoping Canyon, and from 851 to 5032 mgC m-2d-1 in the NSCS. The integrated dark community respiration (IDCR) ranged from 919 to 5848 mgC m-2d-1 in the Kaoping Canyon, and from 435 to 10707 mgC m-2d-1 in the NSCS. The higher IGP was found in summer than in winter for both study areas, primarily due to greater inputs of freshwater from the Kaoping River and/or from the Pearl River. The deeper euphotic depth may be also responsible for higher IGP in the central basin during the summer season. Positive correlations are significant between GP (DCR) and temperature, PAR and nutrients, and negative correlations are also significant between GP (DCR) and salinity, showing the significant impacts of freshwater inputs and climatic changes on GP (DCR). However, GP was determined largely by DCR, and DCR was attributed mainly to BR (bacteria respiration) for both the Kaoping Canyon (ave., 78%) and the NSCS (ave., 65%). In addition, the ratio of IBR/IDCR ranged from 48 to 88% for the Kaoping Canyon and from 58 to 88% for the NSCS. The ratio of IGP/IDCR is an indicator of net ecosystem production, with >1 for the autotrophic system and <1 for the heterotrophic system. The ratio was greater than 1.0 for most stations during summer but was <1.0 away from the nearshore station during winter in the Kaoping Canyon. The ratio was <1.0 for all but stations near the Pearl estuary (H and H1 stations) during both summer and winter in the NSCS, indicating a year-round heterotrophic around the slope and basin of NSCS. However, this ratio was higher in winter than in summer in the NSCS, possibly resulted from higher GP in winter than in summer. The IGP/IDCR may not be the sole factor in determining the air-sea fluxes of CO2. The physical forcing such as temperature and wind velocity may be also important in determining the source or sink of CO2 in the study areas.

Metal-respiring bacteria occupy a central position in a variety of environmentally important processes including the biogeochemical cycling of metals and carbon, biocorrosion of steel surfaces, bioremediation of radionuclide-contaminated aquifers, and electricity generation in microbial fuel cells. Metal-respiring bacteria are presented, however, with a unique physiological challenge: they are required to respire anaerobically on electron acceptors (e.g., Fe(III) oxides, elemental sulfur) that are highly insoluble at circumneutral pH and unable to enter the cell and contact inner membrane-localized respiratory systems. To overcome these physiological problems, metal-respiring bacteria are postulated to employ a variety of novel respiratory strategies not found in other bacteria, including 1) direct enzymatic reduction at the cell surface, 2) electron shuttling between the cell and metal surfaces, and 3) metal solubilization by bacterially-produced organic ligands followed by respiration of the soluble organic-metal complexes. This work highlights my latest findings on the genetic and enzymatic mechanism of metal respiration by Shewanella oneidensis, a facultative anaerobe ubiquitous to redox-stratified natural waters and sediments.

The relationship between temperature and soil respiration has been well explored although uncertainties remain. This thesis examined the relationship between temperature and rates of heterotrophic respiration in soils from three adjacent sub-alpine Australian vegetation types; woodland, shrubland and grassland. Temperature sensitivity of soil (Q10) has recently been a hotly debate topic, one side concluding that decomposition of recalcitrant, less labile components of soil organic matter are insensitive to temperature. Whilst others argue that there is no difference in the temperature sensitivities of labile and recalcitrant carbon pools. Robust modeling of rates of soil respiration requires characterization of the temperature response of both labile and recalcitrant pools. Laboratory incubation provides a means of characterizing the temperature response of rates of respiration whilst reducing the confounding effects encountered in the field, such as seasonal fluctuations in temperature, moisture and substrate supply. I used a novel system that allowed laboratory measurement of gas exchange in soils over a range of temperatures under controlled conditions. Measurements included CO2 efflux and O2 uptake over a range of temperatures from 5 to 40oC, characterization of temperature response and sensitivity, and respiratory quotients. Rates of heterotrophic respiration fitted both exponential and Arrhenius functions and temperature sensitivity varied and depended on the model used, vegetation type and depth in the soil profile. Long-term incubation indicated both labile and resistant pools of carbon had similar temperature sensitivities. Respiratory quotients provided a strongly predictive measure of the potential rate of decomposition of soil C, independent of the temperature response of respiration, providing a tool that may be used alongside derived parameters to help understand shifts in microbial use of C substrates. Vegetation type influenced soil chemical properties and rates of heterotrophic respiration. Rates of respiration correlated well with concentrations of carbon and nitrogen as has been previously observed, unlike previous studies however a positive correlation was observed between indices of plant available phosphorus and respiration. The soils examined were from three adjacent vegetation types formed on common geology, I concluded that vegetation type had a significant influence on soil, in contrast to the commonly held view by ecologists that soil type drives patterns in vegetation. Climatic effects such as longer, dryer hotter summer, reduced snow cover and increased incidence of extreme weather events such as frosts and bushfire are likely to drive patterns in vegetation in this region and therefore have a significant impact on carbon cycling in Sub-alpine Australian soils.

Thesis (M.S.)--University of Michigan, 1986.

Thesis (M.S.)--University of Michigan, 1986. / "A research report submitted in partial fulfillment of the requirements for the degree ..."

Thesis--University of Copenhagen. / Also published in Acta Physiologica Scandinavica, Supplementum, 324. Summary in Danish. Bibliography: p. 105-110.

Thesis (M.S.)--University of Michigan, 1986. / "A research report submitted in partial fulfillment of the requirements for the degree ..."

Thesis (M.S.)--University of Michigan, 1986.