Thesis (Ph. D.)--Brandeis University, 2010. / "UMI:3390495." MICROFILM COPY ALSO AVAILABLE IN THE UNIVERSITY ARCHIVES. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 156-169).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references and footnotes.

Thesis (doctoral)--University of Oulu, 1992. / Includes bibliographical references.

Thesis (Ph. D.)--Florida State University, 2006. / Advisor: Timothy A. Cross, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed June 9, 2006). Document formatted into pages; contains xv, 98 pages. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 69-72).

Thesis (Ph. D.)--Miami University, Dept. of Chemistry and Biochemistry, 2007. / Title from second page of PDF document. Includes bibliographical references.

The status of the myocardial 'high energy phosphate' metabolism is a sensitive marker of the occurrence and progression of heart failure. Magnetic resonance spectroscopy enables non-invasive, direct and potentially quantitative measurements of the phosphate containing metabolites present in the human myocardium. This thesis is primarily concerned with the creation of measurement techniques for cardiac phosphorus magnetic resonance spectroscopy (³¹P-MRS) at the 7 tesla field strength. Chapter 1 provides an overview of the physical basis of magnetic resonance spectroscopy, the myocardial high energy phosphate metabolism, and the clinical relevance of the technique. Chapter 2 describes the advantage of 7 tesla scanners over lower field strengths. The radio frequency coil hardware is characterised experimentally. The multivoxel spectroscopy methods used throughout the thesis are described. Chapter 3 details the implementation of an open source spectroscopy fitting program. It is validated against previous closed-source implementations. The program's use is demonstrated in several clinical studies of heart failure, and to improve a previously implemented ¹H spectroscopy coil combination method. In Chapter 4 the measurement of inorganic phosphate in the presence of overlapping peaks is attempted. Suppression of overlapping peaks, originating from the blood, is tried using B_o gradients, then saturation transfer. The myocardial pH of hypertrophic cardiomyopathy patients is measured. Chapter 5 describes the effect of creatine kinase catalysed chemical exchange on the ³¹P-MRS spectrum. A survey of methods suitable for measuring creatine kinase kinetics at 7 tesla is made. Multi-parametric fitting of variable repetition time saturation transfer data is explored in simulation and experiment. Chapter 6 describes the re-implementation and extension, for dynamic measurements, of the triple repetition time saturation transfer method for two clinical studies at 3 tesla. The creatine kinase forward rate constant is measured in heart failure and healthy cohorts, at rest, and during cardiac stress. In Chapter 7 a Bloch-Siegert B₁ mapping sequence is implemented for ³¹P-MRS. An optimal Bloch-Siegert method for X-nuclear spectroscopy is calculated. B₁maps are validated in skeletal muscle and collected in 5 volunteer's hearts. Chapter 8 uses the Bloch-Siegert B₁ mapping sequence and the four angle saturation transfer method to implement creatine kinase rate measurement at 7 tesla. The first 3D localised creatine kinase rate measurements in the human myocardium are achieved in 10 volunteers.

1H-Magnetic Resonance Spectroscopy (MRS) is a MRI paradigm that allows the levels of specific metabolites to be estimated in vivo [1]. This means that insights into the biochemical changes associated with a rare genetic change that raises the risk of mental disorders, and the impact of having a mental disorder, can potentially be made. In this study the levels of glutamate and N-acetyl-aspartate (NAA) were measured at 3T field strength in three separate voxels: right dorsolateral prefrontal cortex (DLPFC), left DLPFC and the anterior cingulate cortex (ACC). This thesis reports that members of a family that carry a unique t(1;11)(q42.2;q14) translocation that affects DISC1 have a substantially raised risk of developing a range of mental disorders, including bipolar affective disorder, schizophrenia and depression. A genetic change that leads to an increase in the susceptibility to a range of mental disorders is in line with other genetic studies that have been recently reported [2, 3]. The translocation was associated with a significant reduction in right DLPFC glutamate (mean difference= -2.11, CI= -0.24: -3.98, p=0.029) and left DLPFC NAA (mean difference= -1.97, CI= -0.34: -3.61, p=0.020). Changes in these metabolites offer some support to studies in cells and rodents trying to understand the impact of the t(1;11) translocation. More specifically the results offer support to studies that have linked alterations in DISC1's molecular biology to changes in glutamate receptors and mitochondrial function [4-6]. The results need to be interpreted with some caution due to the small sample size and the lack of a significant effect in the bilateral DLPFCs. People with a major mental disorder were also found to have significantly lower levels of glutamate in the left DLPFC (F=3.16, p=0.047). When compared to controls the reductions were significant in the people with a diagnosis of schizophrenia (mean difference= -0.86, CI= -0.19: -1.51, p=0.012), but not in people with bipolar affective disorder. Glutamate levels were significantly correlated with negative symptoms in people with schizophrenia (SANS r= -0.44, CI= -0.07: - 0.70, p= 0.024). The effect of experiencing depressive symptoms was also evaluated due to support for a link in previous studies [7, 8]. Whist the participants were not recruited due their experience of depressive symptoms, metabolite levels were found to be significantly associated with depressive symptoms in all participants with a mental disorder (all three voxels, both NAA and glutamate p < 0.05). The experience of depressive symptoms is not the same experiencing a depressive episode though, and further work may offer more insights into the association between metabolite changes and experience of depression. These findings provide insights into the relationship between diagnosis, current psychopathology and genetic risk in major mental disorders. The thesis provides some support that MRS imaging can be used to try understand neurobiological changes that are associated a genetic change, which is in turn linked to range of mental disorders. Interpreting the results of MRS imaging studies in humans remains challenging due to the complexity of the molecular biology that underpins the estimated metabolite levels, but where there has been a wide range of translational study into a specific protein (or genetic change) MRS may offer further information to help understand any effect in vivo.

The pathophysiology of traumatic brain injury (TBI) includes perturbations to energy metabolism. Improving our understanding of cerebral energy metabolism will lead to strategies that improve clinical outcomes. For the studies in my thesis I used microdialysis to deliver carbon-13 labelled substrates to the human brain. I combined this with nuclear magnetic resonance (NMR) spectroscopy of interstitial fluid sampled from the brain to interrogate glucose, lactate and tricarboxylic acid (TCA) cycle metabolism. Study I: I defined the optimal parameters for quantitative proton and carbon-13 NMR of cerebral microdialysates. Study II: I measured baseline microdialysate metabolite concentrations for brain and muscle and investigated the influence of muscle activity and cerebral catheter placement in grey or white matter on metabolite concentrations. Study III: I used 1,2-13C2 glucose to measure glycolysis and pentose phosphate pathway activity. Glycolysis is the dominant lactate-producing pathway but the pentose phosphate pathway also contributes and is increased in some TBI patients. Study IV: I used arterio-venous gradients to measure glucose and lactate delivery to the brain. There are periods after injury when lactate is imported from the circulation despite relatively high brain lactate levels suggesting up-regulation of lactate transport. Study V: I followed the metabolism of 3-13C lactate and demonstrated that lactate is metabolised by the TCA cycle. This occurs in both normal and injured brain but not in muscle. Study VI: I used 2,3-13C2 succinate to investigate the role of the TCA cycle in producing metabolites that are exported into the interstitium. The TCA cycle is found to be a source of lactate. Succinate delivered to the brain improves redox and enhances glutamate uptake into cells. The implications of the findings in my thesis on existing knowledge of cerebral metabolism are discussed. Strategies that might potentiate cerebral metabolism and improve clinical outcomes are suggested.