This study attempts to develop a method for absolute quantitation in Positron Emission Tomography. This includes the definition of the dimension and the position of a tumour in the brain as well as the evaluation of the amount of drug delivered to the tumour and to surrounding tissues in a pixel-by-pixel way, from the image. The defined objectives can be achieved using the calibrated FWHM values of the distribution of events in the tumour image, versus distance, to determine the dimension and the position of the tumour. The concentration activity in the tumour and the tumour-to-nontumour activity ratios can be obtained from the image, using a modified filter and the calibration of the tomograph. The colour scale of the image can be expressed in absolute units (μCi/ml) and the concentration activity can be evaluated in each pixel of the image or in each volume element of the body. / Thesis / Master of Science (MS)

Though mass spectrometry has earned a central role in the field of proteomics due to its versatility in a wide range of experiments, challenges and complications are still encountered when using mass spectrometry to characterize protein structures, post-translational modifications (PTMs), and abundances. In this dissertation, analytical methods utilizing mass spectrometry have been developed to address challenges associated with both qualitative and quantitative protein characterization. The effectiveness of using multiple pepsin-like proteases, both separately and in mixtures, combined with online proteolysis using a special triaxial probe has been demonstrated on an amyloid beta peptide related to the onset of Alzheimer’s disease. These findings have broad implications in protein structural characterization studies using hydrogen-deuterium exchange mass spectrometry. A wider range of proteases (Lys-C, Glu-C, and trypsin) and multiple fragmentation methods (collisionally activated dissociation, electron transfer dissociation, and decision tree) have been utilized in the discovery-based PTM characterization of extracellular cellulosome proteins of the bioenergy-relevent organism Clostridium thermocellum, resulting in the identification of 85 previously unknown modification sites in 28 cellulosome proteins. These modifications may contribute to the structure and/or function of the cellulosome protein complex. By using peptide internal standards and a triple quadrupole mass spectrometer operating in selected reaction monitoring mode, a method has been developed for the absolute quantitation of the Clostridium thermocellum cellulosome protein machine in samples ranging in complexity from purified cellulosome samples to whole cell lysates as an alternative to a previously-developed enzyme-linked immunosorbent assay method of cellulosome quantitation. The precision of the cellulosome mass concentration in technical replicates is better than 5% relative standard deviation for all samples, indicating high precision of cellulosome mass concentration for this method. Though methods and results presented in this dissertation have implications in the study of Alzheimer’s disease and bioenergy research, more broadly this dissertation focuses on development of methods to contend with some of the more complex challenges associated with protein characterization currently presented to the field of proteomics.