Ability to duplicate an inspired volume level was studied in five healthy males using the psychophysical method of reproduction. Three conditions were evaluated in order to investigate the perceptual cues used for obtaining a specific inspired volume. Conditions were designed to progressively remove cues that might affect the subject's ability to duplicate an inspired lung volume. In each, the subject performed a standard inspiration, spanning from end expiratory position to 35% of inspiratory capacity. Conditions were varied as follows: (1) subjects were instructed to perform both the standard and test (reproduction) inspirations at the same flow rate and beginning at the same lung volume, (2) subjects were instructed to make the flow rate of the test inspiration faster or slower from standard inspiration, and (3) subjects were instructed to begin the test inspiration at a different lung volume than the standard inspirations. The group mean error for all conditions combined for the first day on which each condition was performed was 173 ml, compared to a mean error of 133 ml. Reduction in errors for all conditions from the first to the second day of performance indicates a practice effect. There was no significant difference in errors between conditions. These results indicate the final lung volume, which remained constant for all three conditions, is important for accurate duplication of inspired volume. This finding for learned respiratory movements is comparable to that found by other researchers for skilled limb movements.

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Older individuals are known to adopt a less efficient breathing strategy than young adults during exercise. Whether different strategies are adopted by young and master athletes matched for height, weight and training volume during incremental and constant running is unclear.  In the first part of this thesis, it was demonstrated that during an incremental run to exhaustion and an 8 minute constant intensity run at 90% maximal aerobic speed, master athletes regulate their breathing less efficiently than young athletes.  Major differences in breathing regulation were also observed within the young athletic group (between individuals and between tests) indicating a heterogeneity of response in this population that was, at least partly, linked to baseline expiratory flow rates. An original approach (<i>i.e. </i>using urinary levels of the lung specific protein CC16 to detect a possible disruption of the airway epithelium during exercise in young athletes) was used in the second part of the thesis.  In the first instance, an increase in urinary CC16 after a short period of hyperpnoea of dry air in all the individuals studied (<i>i.e.</i> trained and untrained subjects with and without asthma) was demonstrated.  By comparing the response of summer and winter athletes it was then established that the rise of CC16 post-challenge was independent from the usual environment in which athletes train.  Finally, it was shown that the rise of urinary CC16 is more severe after a short exercise bout performed in cold dry than hot humid air.  Together these results confirm that exercise-induced hyperventilation can have a noxious effect on the fragile airway epithelium of healthy young athletes.

D.Tech. (Biomedical Technology) / Photodynamic therapy (PDT) is an alternative treatment modality for malignant tumours based on the photodamage to tumour cells through a photochemical reaction (Ahn et al., 2013). PDT utilizes a light sensitive photosensitizer (PS) that selectively localizes in tumour cells and is excited by light of a specific wavelength in the presence of molecular oxygen. The excited PS leads to the generation of singlet oxygen or other reactive oxygen species(ROS) which induces cytotoxic damage to cellular organelles and eventually cell death. Singlet oxygen has a very short life and its generation is controlled by the presence of the PS and the laser light (Senge and Radomski, 2013).The subcellular localization site of the PS plays a vital role in determining the effectiveness and the extent of cellular damage as well as the mechanism involved in cell death. Lung cancer is the leading cause of cancer death worldwide in both males and females, with an estimated 1.4 million deaths each year (American Cancer Society, 2011). Therapeutic modalities used in the treatment of lung cancer such as chemotherapy, radiotherapy and immunotherapy have rarely yielded a good prognosis and effective treatment remains a challenging problem to date. An alternative treatment modality with minimal complications such as PDT needs to be explored. Most in vitro PDT experiments are conducted on monolayer cultures and the cellular environment of these cultures does not correspond to that of in vivo studies. Multicellular tumour spheroids (MCTSs) serves as an important model in cancer research for the evaluation of therapeutic interventions since they mimic different aspects of the human tumour tissue environment.

Thesis--Catholic University of America. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 165-172).

Thesis--Ph. D., University of Hong Kong, 1980.

Thesis (M.D.)--University of Hong Kong, 1978.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences