This thesis is focussed on developing new methods and outcomes to assess respiratory function that require little or no volitional effort on behalf of the participants being tested. Specifically to attempt to detach the behaviour of the patient from the accuracy of the test of respiratory function, resulting in techniques that are simpler and easier to administer and undertake for both assessor and participant. It aims to develop methods that reduce the involvement of the participant during assessment of respiratory function. The human body’s way of controlling respiration has evolved into a sophisticated system that optimises breathing pattern to maintain the most efficient homeostatic action of the respiratory system. Eliciting and assessing this automatic response is the key to removing the action of participation from respiratory functiontesting. The focus must therefore be on developing non-invasive, sub-maximal techniques that allow participants to enter into a steady state of respiration and how this can be assessed. Two techniques were investigated; Respiratory Endurance (as the inspiratory work of breathing) and Tidal Breathing Flow Profile, and these were successfully applied in 99 adult participants (68 healthy controls and 31 COPD patients) and 75 children (48 clinical group and 27 healthy controls) who completed 467 respiratory endurance trials whilst seated and exercising, and 249 relaxed tidal breathing trials. The difficulties with lung function assessment are well established and have been described in this thesis. Much recent emphasis has been put on developing existing devices and protocols rather than developing new techniques and approaching these difficulties from alternative viewpoints. This thesis has described the development of innovative techniques to assess the function of the respiratory systems that aim to overcome the issues associated with maximal testing. It was shown that these techniques are easy to undertake for a range of participants, simple to analyse and are able to reliably differentiate between health and disease, suggesting that they could become a useful adjunct to existing methods of respiratory assessment.

The reduction in O2peak at altitude is well documented. Maximal exercise in hypoxia is accelerated through a reduction in O2 supply with contributions from central and peripheral origins of fatigue. Changes in cerebral and muscle oxygenation have not been well characterised during incremental exercise in hypoxia. It is possible attainment of O2peak is driven by the oxygenation profile of these tissues whilst changes in molecular biomarkers of endothelial function could provide some insight into the mechanisms driving systemic and regional O2 delivery and vascular hypoxic sensing capabilities. The first study of this thesis examined the impact of acute hypoxia (FIO2 = 0.12) on the cerebral and muscle oxygenation response to incremental cycling exercise using NIRS (n = 14; age: 23 ± 5yr; height: 1.80 ± 0.07m; weight: 84 ± 8kg). The profiles were characterised at equivalent relative and absolute exercise intensities and molecular blood-borne markers of O2 sensing and function were measured before and immediately after maximal exercise for changes in oxidative stress (A• and 3-NT), NO metabolites (NOx, NO3•, NO2• and RSNO) and cell adhesion molecules (sICAM-1 and sVCAM-1). The key observations from this study were: 1) O2peak decreased by 22% and the magnitude of cerebral and muscle deoxygenation (↓O2Hb and ↑HHb) was greater in hypoxia, 2) the slope for the relative HHb response was similar between conditions whereas there was an accelerated slope across the absolute workloads in hypoxia implying cycling performance was driven by a premature attainment of maximal O2 extraction capacity of the muscle, 3) there was no evidence suggesting cerebral O2 metabolism was impaired in hypoxia however since SaO2 was 78 ± 4% at PPO it is possible the reduction in systemic O2 delivery could have influenced central fatigue, 4) there was a tendency for a rightward shift in the cerebral THb profile in hypoxia and although muscle THb peaked at 80% PPO in both trials, the response also tended to be lower in hypoxia, 5) there was no change in oxidative stress markers and NOx after exercise, 6) RSNO increased and NO2• decreased after maximal exercise. The decline in NO2• was attenuated in hypoxia possibly due to a blunted NO2•-HHb-NO pathway and may explain the systemic hypoperfusion response, 7) The increase in sICAM-1 and sVCAM-1 after exercise was augmented in normoxia, 8) Only when normoxia and hypoxia data was pooled was there a correlation between sVCAM-1 pre-post exercise and O2peak. Intermittent hypoxia (IH) may be used to improve the efficiency of exercise training and as a pre-acclimatisation strategy prior to high altitude ascent. The purpose of the second study was to evaluate the efficacy of a 10 day IH regime consisting of 9x 5 min daily exposures of 9.5% O2 breathing followed by equal periods of normoxia on submaximal and maximal cardiorespiratory responses to exercise in hypoxia. Additionally, cerebral and muscle oxygenation was monitored throughout incremental cycling to exhaustion and changes in NO metabolites (NO3•, NO2• and RSNO) and CAMs (sICAM-1 and sVCAM-1) were measured before and immediately after maximal exercise. The key observations from this study were: 1) a tendency for IH to reduce submaximal O2 and increase O2peak in hypoxia, 2) IH increased the muscle THb response to exercise due an increased intercept for both the muscle O2Hb and HHb in the absence of any change in slope, 4) cerebral oxygenation increased (↑O2Hb) at rest and during exercise, 4) the reduction in nitrite was attenuated in the IH group whilst resting sICAM-1 decreased and the pre-post maximal exercise increase in sICAM-1 was augmented after IH. It is concluded that exercise performance in acute hypoxia is driven by the magnitude of hypoxaemia and an accelerated rate of cerebral and muscle deoxygenation. Molecular biomarkers of endothelial function in particular, NO2• and CAMs, are also influenced by hypoxia and may contribute to the reduction in O2peak. IH may be used to improve exercise economy and O2peak in hypoxia by improving cerebral and muscle oxygenation in the absence of any change in central O2 delivery. It is possible a recalibration of mechanisms that affect NO bioactivation could have enhanced vascular hypoxic sensitivity, O2 delivery and adaptation within brain and muscle tissue which ultimately translated to an improved hypoxic exercise performance. These results give motivation for athletes and mountaineers to incorporate an IH strategy prior to athletic performance at altitude.

It is not clear whether flood-tolerant plants survive in waterlogged soils because they maintain aerobic activity in all regions of the roots, or whether biochemical adaptations to anoxia are involved. Many plants have some capacity for internal ventilation, and so in order to exclude oxygen from the root environment it is necessary to subject both the roots and the shoots to anoxia. Pea and rice seedlings were exposed to anoxia for 1 to 24 h and their tolerances and survival compared. With pea and rice, cv. Oeiras, tolerance of anoxia decreased as the temperature increased, although rice was more tolerant than pea at a given temperature. Increasing amounts of K+ were lost from the roots of whole seedlings during anoxia, and seedling recovery on return to air was associated with the seedlings' ability to reabsorb most of the leaked K+. Aerobic respiration in the root tips was associated with both K+ uptake by pea seedlings, and the recovery and subsequent growth of pea and three varieties of rice after anoxia. All rice varieties were more tolerant of anoxia at 25°C than was pea at 20°C, but differences between the tolerance limits of the rice varieties were apparent. Although some pea and rice seedlings appeared undamaged after anoxia, the subsequent growth rates of pea and rice, cv. IR8, were seriously impaired. Ethanol accumulated around the roots of all seedlings during anoxia, but there was no correlation between the quantity of ethanol produced and the different tolerance limits of the seedlings. Pea seedlings that were prevented from transpiring during anoxia were damaged earlier than controls, possibly because of an increase in the rate of accumulation of a toxic product of anaerobic metabolism in these seedlings. Two percent glucose merely delayed, and did not prevent, the onset of damage in whole pea seedlings during anoxia, nor did it enhance the subsequent growth of the seedlings. Under these conditions, the accumulation of endogenous ethanol to a toxic concentration was considered to have been the more likely cause of seedling death. From the results presented in this thesis and elsewhere, it is concluded that-the immediate cause of seedling death during anoxia is a shortage of substrate for glycolysis, and that the additional effect of ethanol accumulation in some species may reduce their subsequent rate of recovery.

In normal subjects, the ventilatory and mouth occlusion pressure (both total mouth occlusion at 0.1 sec. from beginning of inspiration (P0.1) and the maximum rate of change of mouth occlusion pressure, (dp/dt)max.,) responses to CO2 was studied. All three responses gave similar results. However, the P0.1 response has the dis-advantage that subjects anticipated and were conscious of the occlusion; thus it was not used further. In hypoxia tests too, (dp/dt)max. and ventilatory responses gave similar results. With added airways obstruction, the ventilatory response to CO2 was significantly reduced whereas the (dp/dt) max. response was unaffected, suggesting that (dp/dt) max. reflects the respiratory centre output. In patients with chronic airways obstruction, the normocapnic group showed a significantly lower ventilatory response to CO2 but the (dp/dt) max. response was in the range of the normal subjects in 87% of the patients. The hypercapnic patients showed significantly lower ventilatory and (dp/dt) max. responses to CO2 when compared to that of the normal subjects. The resting PaCO2 showed a better correlation with (dp/dt) max. response than with ventilatory response. The ventilatory response in the patients showed a significant correlation with the degree of airways obstruction whilst (dp/dt) max. response did not show any such relationship. This suggests that (dp/dt) max. may be a reliable index of respiratory centre output independent of airways obstruction. In anaesthetized rabbits, ventilation, (dp/dt) max. and the average rate and total diaphragmatic electrical activity (integrated EMG) in response to CO2 was compared. In unobstructed breathing, all four responses gave similar results. With added airways obstruction, the ventilatory response was significantly reduced whilst the other three responses were unaffected. Changes in (dp/dt) max. paralled changes in EMG activity with increases in PCO2. Thus it is shown again that (dp/dt) max. is independent of airways obstruction, and can be said to reflect the respiratory centre neural output. In 47 normal subjects, the ventilatory response to exercise (when exercise is expressed as CO2 produced and O2 uptake) was studied in trained and untrained subjects. The exercise ventilatory response was compared to the CO2 response as measured by ventilation and in some subjects by (dp/dt) max. response. It is found that trained subjects had a significantly lower CO2 response and a lower ventilatory response to exercise than the untrained. The ventilatory and (dp/dt) max. responses correlated significantly with exercise ventilatory response. A similar correlation was found between (dp/dt) max. and ventilatory response to hypoxia and exercise ventilatory response. The breathing pattern of man was also studied to find its relationship with the above findings.

The standard metabolic rates of the euryhaline starry flounder (Platichthys stella.tus) when acclimated to 30 parts per thousand (‰) and 10.8 parts per thousand (isotonic to plasma) salinities are not significantly different. However, the standard metabolic rate is significantly lower in fish acclimated in 2‰ salinity. Metabolic rate was directly proportional to the frequency of an electrical stimulation of 60 volts to a maximum frequency of 3 stimulations per minute. An estimate of the standard metabolic rate was obtained by extrapolating the activity curve to a stimulation frequency of zero. Although the estimate was similar to previously determined standard metabolic rates the confidence intervals were too great to allow detailed comparisons. QO₂ of each major organ was obtained from three groups of fish held in the three salinities. Only gill showed a significant change with regard to salinity. The QO₂ was least in the isotonic salinity and was significantly greater in both higher and lower salinities. A summation value of tissue respiration was obtained for each group of fish. The summated tissue values were below the standard metabolic rates of fish in 30‰ and 10.8‰ salinity but above the standard metabolic rate of fish in 2 ‰ salinity although they did not significantly differ from each other. / Science, Faculty of / Zoology, Department of / Graduate

Using a variety of preparations, (intact birds during treadmill and overground walking/running and free-flight; decerebrate birds during electrically induced walking/running, passive wing flapping, and electrically induced wing flapping and "Active" flight), this thesis examines some of the mechanisms involved in the production and control of locomotor-respiratory coordination (entrainment) during alternating hindlimb locomotion (walking/running) and synchronous forelimb locomotion ("flight") in the Canada goose. Significant coordination of locomotor and respiratory rhythms was observed during both modes of locomotion in intact as well as decerebrate birds. While coordination of forelimb motion and respiration was virtually complete, coordination of hindlimb motion and respiration was sporadic. The level of entrainment during hindlimb locomotion, however, increased with increased stride frequency, rather than increased work rate, suggesting that proprioceptive feedback from the limbs is involved in the production of locomotor-respiratory entrainment. Further evidence for a role of proprioceptive feedback in the production of entrainment was provided by the entrainment of respiration by passive wing motion in decerebrate geese. Although feedback from the periphery was sufficient for the entrainment of wing motion and respiration, motor nerve outputs to the wing and respiratory musculature were also synchronized in paralyzed, decerebrate birds during electrically induced activity, in the complete absence of phasic afferent feedback. Thus, both feedback and feedforward mechanisms appear sufficient for the coordination of wing beat and respiration. / Science, Faculty of / Zoology, Department of / Graduate

Contactless breathing estimation using radars has been explored since the 1960s and an accurate system with the ability to continuously monitor the health of non-critical patients without obstructing their day to day lives could significantly improve their well being. The current state of the art in this area does not have the accuracy required to work in a real-world environment and many of the existing methods have been tested only under very controlled situations. Low performance of breathing estimation algorithms under different scenarios inspired us to improve breathing estimation algorithms and develop a system for automated analysis of large number of algorithms against data from the reference sensors. A novel accurate breathing rate estimation method and a system to use multiple algorithms on the same set of data in real-time and identify the best performing algorithm dynamically to report breathing rate have been proposed in this thesis. In addition, automated data-collection and processing frameworks were developed to collect a large amount of data and process them and generate reports automatically. The proposed system has been tested under multiple test-cases involving multiple subjects and the accuracy of both new and existing algorithms have been evaluated by comparing the results with reference data collected using a respiration belt. The mean absolute error rate of breathing rate estimation after conducting experiments for a total of 9 subjects was found to be 0.79 breaths per minute for the novel CEEMD based method presented in this thesis. The mean absolute error rate after applying the scoring algorithm to select the best performing algorithm is 0.78 breaths/minute.

Photosynthesis, photorespiration and differences in their interactions among species were studied. In the first of two parts of the investigation, the CO₂ compensation concentration of members of the Gramineae and other plants was determined with an infrared CO₂ analyzer. In some cases the Initial products of ¹⁴C0₂ fixation and leaf anatomy were also examined. In plants with low compensation values (lacking photo-respiration) the initial products of photosynthesis were formed by the C₄-dlcarboxylic acid pathway. High compensation plants (with photorespiration) produced compounds typical of the Calvin cycle. The leaf veins of low compensation species were surrounded by a specialized parenchyma bundle sheath containing a high concentration of chloroplasts with large quantities of starch. Low compensation members of the Gramineae belonged to the arlstidoid, chloridoid-eragrostoid and panicoid lines of evolution. Of the genera confined to these phylogenetic lines, Panlcum was found to differ in photosynthetlc physiology and bundle sheath characteristics at the subgeneric level. This type of photosynthetlc diversity also occurred within Cyperus (Cyperaceae), Atriplex and Bassia (Chenopodiaceae). Despite these differences, the correlation between type of photosynthetlc pathway, compensation value and leaf anatomy was consistent. The literature indicates that low compensation grasses have photosynthetic rates that are about double those of plants with photorespiration correlated with a temperature optimum for photosynthesis of about 35°. Species with photorespiration have optima within the range 10-25°. Some simple assay procedures proposed on the basis of these correlations allow rapid determination of the physiological and biochemical status of plants with respect to photosynthesis. In the second part of the investigation, some published studies of photorespiration and glycolate oxidation were reexamined and correlated by infrared CO₂ analysis. Photosynthetic rate data at different O₂ tensions for wheat, oat and corn seedlings fed 3-(3,4-dichlorophenyl)-l, 1 dimethyl urea (DCMU) indicated that dark respiration continued in the light when photosynthesis was completely inhibited. Photorespiration was also inhibited. The O₂ sensitivity of glycolate-stimulated CO₂ production was found to be compatible with the proposal that glycolate is a substrate of photorespiration. Both 'in vivo' and 'in vitro' studies of the alga Nitella flexilis revealed a pathway of glycolate oxidation resembling that of higher plants. DCMU inhibition of photosynthesis by Nitella gave results similar to those for the monocotyledons tested. Under very low light intensity, CO₂ compensation in corn was measurable but was not sensitive to high O₂ concentration. It appears that the lack of photorespiration in this plant is not the end result of efficient internal recycling of CO₂ to photosynthesis. / Science, Faculty of / Botany, Department of / Graduate

Weight-specific oxygen consumption of midgut gland tissue of Hemigrapsus nudus has been investigated at three levels of salinity (35%, 75% and 125% sea water), two levels of experimental temperature (5°C and 20°C) and four acute (Warburg) temperatures (5°, 10°, 15° and 20°C) in all combinations for each season (summer and winter). Metabolic-temperature curves reveal that at standard baseline conditions where the animals are held 24 hr at their respective seasonal temperature and salinity, midgut gland respiration is highest at all acute temperatures in the summer animals. Acutely measured metabolic-temperature curves for midgut gland tissue show that winter animals acclimated to their opposite seasonal conditions of temperature and salinity for 10 days demonstrate the greatest degree of acclimation. The effect of experimental temperature is statistically and biologically significant. The highest respiration rate is at 5°C. Low temperature (5°C) may provide a greater thermal stress than a high temperature (20°C) resulting in a higher rate of oxygen consumption. Experimental temperature also influences the seasonal respiratory response of midgut gland tissue to salinity. In summer animals there is no correlation of midgut gland respiration to salinity at 5°C. There is a increase in respiration rate as the osmotic gradient between the blood and medium increases at the seasonal baseline temperature of 20°C. Winter animals held at the seasonal baseline temperature of 5°C demonstrate a "V-shaped" relationship to salinity with the lowest respiratory response in 75% sea water where the gradient between the blood and medium is minimal. Animals held at 20°C increase respiration with an increase in salinity. It is suggested that the metabolic activity of midgut gland from summer animals may be related to the maintenance of a osmotic gradient between the blood and medium or alternatively to the energy demands associated with new exoskeleton formation. The proposal is put forth that midgut gland respiration in winter animals may indicate osmotic work being done to maintain the osmotic gradient between the blood and medium. The production of a urine hypotonic to the blood may also assist winter animals in regulation of blood electrolytes. The regression coefficients of weight-specific oxygen consumption as a function of body weight were not significantly different from zero at the 0.01 probability level. / Science, Faculty of / Zoology, Department of / Graduate

The significance of the difference between the group mean scores in each item was determined using Fisher’s t statistic at the 5 per cent level of confidence. The results indicate that the Control group improved significantly in all the Vitalometer items in amounts similar to the mean improvements of the exercise groups. It was concluded that influences other than training effects were responsible for the changes in the Vitalometer test scores. The variables therefore, were of no further interest for this study. The Bonne Santé group evidenced significant improvements in the Heartometer Resting Pulse Rate (this improvement, however, was based on data which appeared to be unreliable and thus suspect)', the Area Under The Curve-Sitting, the Sitting and Standing Systolic Amplitudes, the Two Minute Recovery Pulse Count Post 24 Steps Per Minute. The Rhythmic Gym group showed significant improvements in the Area Under The Curve-Sitting, and the Sitting Systolic Amplitude. The separate training regimens followed by each of the experimental groups were considered to be of insufficient frequency and intensity to produce uniform and physiologically important improvements in the cardiovascular and respiratory fitness levels of the subjects. The Bonne Santé group showed greater relative improvement in fitness partly because the members tended to be less fit initially than the subjects in the Rhythmic Gym group, and partly because they spent more hours in exercise each week. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate