The phosphatidylinositol-3-kinase/AKT (Protein Kinase B)/mammalian target of rapamycin (PI3K/AKT/mTOR) signalling pathway, downstream of tyrosine kinase receptors, is upregulated in human cancers including breast and colon cancers. Glycogen synthase kinase 3 (GSK 3) is a serine/threonine protein kinase plays important role in various cellular processes including glycogen synthesis mediated by insulin signalling pathway. Moreover, 5' adenosine monophosphate activated protein kinase (AMPK), a crucial cellular energy sensor, has regulatory role in cell growth and proliferation through mTOR pathway. Phosphatidylcholine (PtdCho) is the major phospholipid in the mammalian cell membranes and is mainly synthesized by the CDP-choline pathway. Malignant transformation has been reported to be associated with altered choline metabolism. Hyperactivation of the PI3K/AKT signalling pathway upregulates the key enzymes of phospholipid metabolism. The first line antidiabetic drug, metformin, modulates glucose and concomitant lipid metabolism through AMPK activation. Studies suggest phosphatidylcholine biosynthesis and breakdown through CDP-choline pathway are modulated by glucose metabolism and de novo fatty acid synthesis. Cancer cell growth inhibitory effect of PI3K/AKT/mTOR/GSK3 pathway inhibitors and metformin were investigated by cytotoxic assay, western blot and cell cycle analysis in breast and colon cancer cells. IC50 values of anticancer drugs and combination indices between drug combinations were determined. 31P-NMR was carried out on cell extracts after drug treatments. [14C (U)] glucose and [3H] choline incorporation into lipids were also determined. All inhibitors targeting PI3K/AKT/mTOR signaling pathway, GSK3 and metformin have cancer cell growth inhibition. By 31P-NMR, PI3K/AKT/mTOR pathway inhibition induced agent-specific changes in PCho intensity. Increased UDP-sugars observed in breast and colon cancer cell extracts treated with LY294002 and AZD8055, an effect abrogated by inclusion of a GSK3 inhibitor. A link between glycolytic intermediates and phosphatidylcholine biosynthesis was investigated by metformin and GSK3 inhibitor in breast and colon cancer cells.

No description available.

Optical coherence tomography (OCT) has been emerging as a promising imaging technique, with a strong capability of non-invasive, in vivo, high resolution, depth-resolved imaging. There is a great potential to use OCT to guide the treatment of arrhythmias, to prevent preterm birth, and to detect breast cancer. To facilitate the clinical applications, this thesis presents three image analytic tools to characterize biological tissue: 1) automated fiber direction analysis; 2) automated volumetric stitching; 3) automated tissue classification. The fiber direction analysis consists of a particle-filter-based 3D tractography scheme and a pixel-wise fiber analysis scheme. The stitching algorithm enlarges the field of view of current OCT system from millimeter to centimeter level by volumetric stitching using scale-invariant feature transform. Based on relevance vector machine, a region-based classification scheme and a grid-based classification scheme are developed to automatically identify tissue composition in human cardiac tissue and human breast tissue. These tools are collaboratively used to study OCT images from cardiac, cervical, and breast tissue. In cardiac tissue, we apply the fiber orientation analysis to reconstruct 3D cardiac myofibers tractography and perform pixel-wise fiber analysis on the collagen region within human heart. In addition, we apply the region-based algorithm to segment and classify tissue compositions, such as collagen, adipose tissue, fibrotic myocardium, and normal myocardium, over a single or a stitched OCT volume. Using our algorithm, we observe fiber directionality change over depths and find that the fiber orientation changes more dramatically in atria than in ventricle. We also observe different dispersion patterns within collagen layer. In cervical tissue, our stitching algorithm enables a paramount 3D view of entire axial slices. Together with pixel-wise fiber orientation scheme, we analyze the difference of dispersion property within inner/outer regions of four quadrants. We observe two dispersion patterns in pregnant and non-pregnant cervical tissue at the location close to upper cervix. In addition, we discover that an increasing trend of dispersion and an increasing trend of penetration depth from internal orifice (os) to external os. In breast tissue, we visualize various features in both benign and malignant tissues such as invasive ductal carcinoma (IDC), ductal carcinoma in situ, cyst, and terminal duct lobule unit in stitched OCT images. Focusing on the automated detection of IDC, we propose a hierarchy framework of classification model and apply our classifier in two OCT systems and achieve both reasonable sensitivity and specificity in identifying cancerous region.

Heart disease has remained the deadliest disease in the United States for the past 100 years. Imaging methods are frequently employed in cardiology in order to help clinicians diagnose the specific type of heart disease and to guide treatment decisions. Ultrasound is the most frequently used imaging modality in cardiology because it is inexpensive, portable, easy to use, and extremely safe for patients. Using a variety of imaging processing techniques, deformations exhibited by the cardiac tissue during contraction can be imaged with ultrasound and used as an indicator of myocardial health. This dissertation will demonstrate the clinical implementation of two ultrasound-based strain estimation techniques developed in the Ultrasound and Elasticity Imaging Laboratory at Columbia University. Each of the two imaging methods will be tailored for clinical applications using techniques for optimal strain estimation derived from ultrasound and imaging processing theory. The motion estimation rate (MER) used for strain estimation is examined in the context of the theoretical Strain Filter and used to increase the precision of axial strain estimation. Diverging beam sequences are used to achieve full-view high MER imaging within a single heartbeat. At approximately 500 Hz, the expected elastographic signal-to-noise ratio (E(SNRe|ε)) of the axial strain becomes single-peaked, indicating an absence of “peak-hopping” errors which can severely corrupt strain estimation. In order to mediate the tradeoff in spatial resolution resulting from the use of diverging beams, coherent spatial compounding is used to increase the accuracy of the lateral strain estimation, resulting in a more physiologic strain profile. A sequence with 5 coherently compounded diverging waves is used at 500 Hz to improve the radial SNRe of the strain estimation compared to a single-source diverging sequence at 500 Hz. The first technique, Myocardial Elastography (ME), is used in conjunction with an intracardiac echocardiography (ICE) system to image the formation of thermal ablation lesions in vivo using a canine model (n=6). By comparing the systolic strain before and after the formation of a lesion, lesion maps are generated which allow for the visualization of the lesion in real-time during the procedure. A good correlation is found between the lesion maps and the actual lesion volume as measured using gross pathology (r2=0.86). The transmurality of the lesions are also shown to be in good agreement with gross pathology. Finally, the feasibility of imaging gaps between neighboring lesions is established. Lesion size and the presence of gaps have been associated with the success rate of cardiac ablation procedures, demonstrating the value of ME as a potentially useful technique for clinicians to help improve patient outcomes following ablation procedures. The second technique, Electromechanical Wave Imaging (EWI), is implemented using a transthoracic echocardiography system in a study of heart failure patients (n=16) and healthy subjects (n=4). EWI uses the transient inter-frame strains to generate maps of electromechanical activation, which are then used to distinguish heart failure patients from healthy controls (p<.05). EWI was also shown to be capable of distinguishing responders from non-responders to cardiac resynchronization therapy (CRT) on the basis of the activation time of the lateral wall. These results indicate that EWI could be used as an adjunct tool to monitor patient response to CRT, in addition to helping guide lead placement prior to device implantation.

The goal of this dissertation is to demonstrate the utility of portable, small-scale diffuse optical spectroscopic (DOS) systems for the diagnosis and treatment monitoring of various diseases. These systems employ near-infrared light (wavelength range of 650nm to 950nm) to probe human tissue and are sensitive to changes in scattering and absorption properties of tissues. The absorption is mainly influenced by the components of blood, namely oxy- and deoxy-hemoglobin (HbO2 and Hb) and parameters that can be derived from them (e.g. total hemoglobin concentration [THb] and oxygen saturation, StO2). Therefore, I focused on diseases in which these parameters change, which includes vascular diseases such as Peripheral Atrial Disease (PAD) and Infantile Hemangiomas (IH) as well as musculoskeletal autoimmune diseases such as Rheumatoid Arthritis (RA). In each of these specific diseases, current monitoring techniques are limited by their sensitivity to disease progression or simply do not exist as a quantitative metric. As part of this project, I first designed and built a wireless handheld DOS device (WHDD) that can perform DOS measurements at various tissue depths. This device was used in a 15-patient pilot study for infantile hemangiomas (IH) to differentiate diseased skin from normal skin and monitor the vascular changes during intervention. In another study, I compare the ultra-small form- factor WHDD’s ability to monitor synovitis and disease progression during a patient’s treatment of RA against the capabilities of a proven frequency domain optical tomographic (FDOT) system that has shown to differentiate patients with and without RA. Learning from clinical utility of the WHDD from these two studies, I adapted the WHDD technology to develop a compact multi- channel DOS measurement system to monitor perfusion changes in the lower extremities before and after surgical intervention for patients with peripheral artery disease (PAD). Using this multi- channel system, which we called the vascular optical spectroscopic measurement (VOSM) system, our group conducted a 20-subject pilot study to quantify its ability to monitor blood perfusion before and after revascularization of stenotic arteries in the lower extremities. This proof-of- concept study demonstrated how DOS may help vascular surgeons perform revascularization procedures in the operating room and assists in post-operative treatment monitoring of vascular diseases.

Orientador: Vânia de Vasconcelos Machado / Coorientador: Noeme Sousa Rocha / Banca: Priscila Macedo de Souza / Banca: Rogério Martins Amorim / Resumo: A artéria carótida comum em equinos se trifurca com algumas variações anatômicas e é o principal vaso que fornece sangue arterial para o cérebro, sendo que é conhecido que sua oclusão causa lesões encefálicas em ratos e humanos. Há muito pouca literatura a respeito de estudos anatômicos e ultrassonográficos desse vaso nessa espécie. Esse estudo avaliou a artéria carótida comum de 50 equinos da raça Quarto de Milha em diferentes idades, divididos em três grupos (grupo I: >2anos, n=14; grupo II: 3-10 anos, n=21; grupo III 15-30 anos, n=15), e obteve valores de referencia para espessura intima-media (EIM), índice de resistividade (IR), índice de pulsatilidade (IP) e diâmetro para ambas artérias carótidas comuns. Os exames foram feitos utilizando um transdutor de 18 MHz no sulco jugular, na altura de C5-C6. O diâmetro esquerdo médio foi de 8,71 ± 1,09 mm para o grupo I; 10,11 ± 0,72 mm para o grupo II e 10,72 ± 0,96 mm para o grupo III. O diâmetro direito médio foi de 8,92 ± 1,24 mm para o grupo I; 10,96 ± 1,06 mm para o grupo II e 11,76 ± 1,07 mm para o grupo III. A EIM foi de 0,90 ± 0,15 mm; 1,02 ± 0,09 mm e 0,97 ± 0,10 mm para os grupos I, II e III, respectivamente. Os valores médios de IR e IP obtidos foram 0,75 ± 0,07 e 1,63 ± 0,33 para o grupo I; 0,81 ± 0,06 e 2,08 ± 0,46 para o grupo II; 0,90 ± 0,10 e 3,20 ± 0,74 para o III, respectivamente. As variáveis IR, IP e EIM não são influenciadas por sexo ou lado, mas sim por idade. Já o diâmetro está correlacionado com o lado e idade, sendo sempre maior do lado direito / Abstract: Common carotid artery in horses trifurcates with some anatomical variations and it is the main supply of arterial blood to the brain. It is known that carotid occlusion can cause encephalic lesions in rats and humans. There are few studies on this vessel, including ultrasonografic evaluation of his vessel in this species. This study evaluated the common carotid artery in 50 American Quarter horses with different ages, separated into three groups (group I: >2years, n=14; group II: 3-10 years, n=21; group III 15-30 years, n=15), and reference values for intima-media thickness (IMT), resistivity index (RI), pulsatility index (PI) and diameter were obtained for both arteries. Exam was performed using an 18 MHz transducer on jugular groove, on level of C5-C6. Mean left diameter was 8.71 ± 1.09 mm for group I; 10.11 ± 0.72 mm for group II and 10.72 ± 0.96 mm for group III. Right diameter was 8.92 ± 1.24 mm for group I; 10.96 ± 1.06 mm for group II and 11.76 ± 1.07 mm for group III. IMT was 0.90 ± 0.15 mm; 1.02 ± 0.09 mm and 0.97 ± 0.10 mm for groups I, II and III, respectively. Mean RI and PI obtained were 0.75 ± 0.07 and 1.63 ± 0.33 for group I; 0.81 ± 0.06 and 2.08 ± 0.46 for group II; 0.90 ± 0.10 and 3.20 ± 0.74 for group III, respectively. The variables RI, PI and IMT are not influenced by gender or side, but were by age. Diameter was influenced by both, age and side, and right diameter was always greater than the left / Mestre

Wang, Jing. / Thesis Ph.D. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 123-151). / Abstracts also in Chinese. / Title from PDF title page (viewed on 19, September, 2016).

Generating MR image contrast from exogenous contrast media through chemical exchange saturation transfer (CEST) offers several exciting new possibilities, such as multicolored imaging, the interleaving of pre- and post-contrast images, and the potential to perform ratiometric metabolic imaging. The major limitation of the deployment of CEST imaging is the comparatively high detection limits of exogenous agents and particularly at the low B1 power levels required to meet SAR requirements. The large chemical shifts afforded by paramagnetic (paraCEST) agents permit more rapid exchange kinetics and therefore potentially more effective contrast agents. Despite comparatively large chemical shifts, many Ln3+ DOTA-tetraamide (DOTAM) chelates traditionally investigated as CEST agents are predicted to have exchange kinetics that are considerably faster than optimal at very low B1 powers. This work explores two methodologies for slowing water exchange kinetics in Ln3+ DOTAM chelates and improving CEST imaging: structural manipulation and encapsulation. In the first method, rigid Ln3+ NB-DOTAM chelates with hydrophobic amide substituents was thoroughly studied using NMR spectroscopy techniques in order to assess their ability to produce CEST contrast at low B1 power levels. NMR techniques utilized included 1H NMR, variable temperature, COSY, and CEST experiments. The phenyl amide substituent in the pseudo-axial position afforded chelates with considerably slow water proton exchange rates and appreciably more CEST contrast than isomeric chelates with the amide substituent in the pseudo-equatorial position. The second method involved characterizing a vesicle system to be used for encapsulating a Ln3+ DOTAM chelate. The vesicles prepared were analyzed using the following NMR techniques: 1H NMR, T1, shift reagent, and CEST experiments. The vesicle system chosen for study did not afford slow water exchange kinetics to enhance CEST contrast. A second vesicle system was attempted but the vesicle synthesis was difficult, parameters studied were not optimized, and the second system did not exhibit slow water exchange with the limited amount of experiments run and data collected.

Since the advent of functional magnetic resonance imaging (fMRI) and the rise in popularity of its use for resting state functional connectivity mapping (rs-FCM) to non-invasively detect correlated networks of brain activity in human and animal models, many resting state FCM studies have reported differences in these networks under pathologies such as Alzheimer’s or schizophrenia, highlighting the potential for the method’s diagnostic relevance. A common underlying assumption of this analysis, however, is that the blood oxygen level dependent (BOLD) signal of fMRI is a direct measurement of local neural activity. The BOLD signal is in fact a measurement of the local changes in concentration of deoxy-hemoglobin (HbR). Thus, it is imperative that neurovascular coupling—the relationship between neuronal activity and subsequent hemodynamic activity—be better characterized to enable accurate interpretation of resting state fMRI in the context of clinical usage. This dissertation first describes the development and utility of WFOM paradigm for the robust and easily adaptable imaging of simultaneous neuronal and hemodynamic activity in awake mouse models of health or disease in strains with genetically encoded fluorescent calcium reporters. Subsequent exploration of resting state WFOM data collected in Thy1-GCaMP3 and Thy1-GCaMP6f mouse strains is then presented, namely the characterization of spatiotemporal patterns of neuronal and hemodynamic activity and different modulatory depths of neuronal activity via a toolbox of unsupervised blind source separation (e.g. k-means clustering) and supervised (e.g. non-negative least squares, Pearson correlation) analysis tools. The presence of these different modulatory depths of neuronal activity were then confirmed in another Thy1-jRGECO1a mouse strain using the same imaging scheme. Finally, the dissertation documents the application of the WFOM paradigm and select analysis tools to a novel mouse model of diffusely infiltrating glioma, through which neuronal and hemodynamic activity changes during diffusely infiltrating glioma development which impact temporal coherence of the tumor region activity relative to non-tumor regions activity were recorded and analyzed. The paradigm also allowed for recording of numerous spontaneous occurrences of interictal neuronal activity during which neurovascular coupling is modified in the tumor, as well as occurrences of non-convulsive generalized seizure activity (during which neurovascular is non-linear and cortex eventually suffers hypoxia). The detection of spatiotemporal patterns and different modulatory depths of activity in the awake mouse cortex, as well as observation of changes in functional activity in the context of diffusely infiltrating glioma, provide us with new insights into the possible mechanisms underlying variations in resting state connectivity networks found in resting state fMRI studies comparing health and disease states.

A prospective intervention study, using clinical practice improvement (CPI) methodology, was undertaken to reduce unnecessary x-ray examinations in the early management of patients presenting to the Emergency Department (ED). This was achieved through raising the awareness of medical and allied health staff to medical radiation by means of clinical education and implementing evidence based diagnostic imaging requisition. The main study was conducted in the ED of a public hospital located in the western Sydney, Australia. A second hospital within the area health service, with similar bed size, activity levels and demographics, was used as the control site. The first phase intervention raised the awareness of the health professionals to medical radiation. The second phase intervention used CPI methodology to attain efficient clinical practices so as to eliminate unnecessary examinations and requests. A multi-disciplinary CPI Project Team involved in the process of imaging examination requisition was empowered to improve the appropriateness of the requested examination utilisation. This it achieved mainly through the implementation of evidence based clinical decision rules and imaging guidelines. An additional method of validating the outcomes was provided through the simultaneous rollout of the interventions at another hospital within the same area health service. At the completion of the study, unnecessary examinations such as Skull, Ribs, Nasal Bone and Kidney Ureter Bladder (KUB) requests at the intervention Hospital site were significantly reduced by 92.6% (p (less than) 0.0001), whereas at the control site Hospital there was minimal reduction which was found to be not statistically significant (p=0.2110). Other frequently requested examinations such as Ankle, Knee and Spine requests were marginally though significantly reduced at the intervention Hospital by 22.7% (p (less than) 0.001), whereas at the control site Hospital the reduction was similarly found to be not significant (p=0.1055). Most importantly, the overall x-ray requisition for every 100 ED presentations at Hospital ‘B’ was reduced by 27%. The results of this study, demonstrated that Radiation Awareness educational programs, targeting medical and allied health staff, will reduce the unnecessary requisition of examinations found not to contribute to the process of the patient’s clinical management. The use of a CPI project approach was found to be important in the process of establishing, implementing and sustaining the achieved improvements, and in particular, the rules and guidelines of evidence based imaging requisition. Importantly, the study also confirmed that the CPI methodology that had been used for the main intervention was adaptable to other organisations when it was found to have been successfully rolled out at another hospital. This confirmed that the main outcomes of the investigation could be generalised to other health facilities. There was an immediate reduction in the requisition of unnecessary examination similar to the results at the main intervention hospital. The implementation and adoption of the CPI intervention across the health care system in general could significantly reduce unnecessary x-ray examinations, saving significant health care resources, and sparing patients from potential cancer risks associated with avoidable exposure to ionising medical radiation. / Doctor of Philosophy (PhD (Health))