Phosphorus magnetic resonance spectroscopy and spectroscopic imaging (31P-MRS/MRSI) non-invasively provide very important information regarding energy metabolism as they can detect high energy metabolites and membrane phospholipids in vivo. They have repeatedly proven their utility in the study of healthy and disease conditions, as many disorders are related to imbalances in bioenergetic processes. However, they are not often used in a clinic setting as there are technical challenges that lead to very long acquisition times. To address this issue, the present work focused on the implementation of two fast phosphorus magnetic resonance spectroscopic imaging (31P-MRSI) pulse sequences. The first one, "fidEPSI" uses a flyback echo planar readout trajectory calculated in real time to achieve an acceleration factor up to x10. The second, "fidepsiCS" further accelerates the acquisition by combining the flyback EPSI readout with a compressed sensing (CS) sampling scheme. For this latter approach two different data reconstruction processes were compared. Both sequences were tested in phantoms as well as in skeletal muscle and brain tissues of healthy volunteers. The results showed feasibility of the flyback Echo Planar Spectroscopic Imaging (EPSI) to acquire good quality data in a fraction of the time when compared to traditional phase encoded MRSI. Furthermore, the compressed sensing approach was used in an exercise-recovery paradigm to evaluate skeletal muscle high energy phosphate dynamics, achieving a temporal resolution of 9 seconds. Additionally, the comparison of CS reconstruction algorithms suggested that a low-rank approach is more suitable for 31P-MRSI data, compared to traditional thresholding, due to the fact that it exploits the sparsity of the NMR signal as the least number of spectral peaks rather than the fewest amount of non-zero values. Overall, this thesis presents new accelerated methods for the acquisition of 31P-MRSI, and its use in the evaluation of energy metabolism. / Thesis / Doctor of Philosophy (PhD)

Sun, Fenghua. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 177-204). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (Dr. P.H.)--University of Texas Health Science Center at Houston, School of Public Health, 1993. / Typescript. Includes bibliographical references (leaves 105-110).

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2003. / Includes bibliographical references (leaves 35-38). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2003. / Includes bibliographical references (leaves 35-38).

Recovery from exhaustive exercise in the white muscle of rainbow trout (Oncorhynchus mykiss) was used to examine the role of the adenylates in the control of energy metabolism and to assess the validity of equilibrium models of the behaviour of the high energy phosphates. The difficulty of obtaining muscle samples from fish makes detailed analysis of the behaviour of the labile high energy phosphates complex. The use of a new sampling procedure, the infusion of a lethal dose of anaesthetic via an indwelling cannula, minimized this problem. At exhaustion [ATP] and [PCr] were depressed by 75 and 80% respectively relative to the resting values. [ATP] depletion was mirrored by a stoichiometric increase in [IMP]. During recovery [PCr] returned to the resting level within 2 hours, but [ATP] recovery was slow and not complete until 24 hours post exercise. In contrast, energy charge and RATP(the proportion of the free adenylate pool phosphorylated to ATP) were, if anything, higher than the resting values by 2 hours post exercise. Therefore, [ATP] and energy status can be dissociated in tissues like fish white muscle because of the action of the purine nucleotide cycle. At 2 hours post exercise the calculated free ADP concentration dropped to less than one tenth the value at rest. As a result the [ATP] / [ADP] free ratio increased by nearly 6 fold. This condition may be required for glycogen resynthesis from lactate in muscle. Several similar equilibrium models of the behaviour of the adenylates and PCr were applied to the fish white muscle system. In general, the models well describe the relationship between the high energy phosphates. However, the definition of the high energy phosphate pool introduces some complications since this includes the total [ATP]. Because of the action of AMP deaminase the [ATP] concentration can change without measurable changes in the energy status, which is not considered in any of the models. As long as the extent of IMP formation is known the models can be applied, but since the formation of IMP may vary from fish to fish or with exercise regime the models lose much of their predictive power. / Science, Faculty of / Zoology, Department of / Graduate

Bibliography / Thesis (MScMedSc (Biomedical Sciences. Medical Physiology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Male infertility is often associated with impaired sperm motility and morphology (asthenoteratozoospermia) for which there is no specific therapeutic treatment. It has come to light that the modification and expression of human sperm proteins play a crucial role in sperm function. In the present study, we present proteomic data of human spermatozoa in the context of sperm dysfunction. Novel techniques have been used to successfully isolate and identify differences in protein expression on a cellular level associated with asthenoteratozoospermia. In the first part of the study, differences in protein expression within the total sperm proteome were investigated between immature and mature sperm populations. Semen was collected from healthy donors (n=23) and separated into mature and immature sperm populations by 3-layer Percoll gradient centrifugation. Cells were washed and motility and morphology were measured by computer assisted sperm analysis (CASA). For the proteomic investigation cells were lysed and proteins separated by means of two-dimensional gel electrophoresis (2D electrophoresis). PD-Quest was used to identify the differentially expressed proteins. The protein spots of interest were excised and subjected to in-gel digestion. Peptides were separated by High Pressure Liquid Chromatography (HPLC) analysis and amino acid sequences determined by mass spectrophotometry. Proteins were identified by Mascot, using the Swiss Prot database. The results show that the motility (immature; 26.1±1.75% total motile cells vs. mature; 60.93±3.24% total motile cells; p<0.001) and morphology parameters (immature; 64.1±2.75% normal head morphology vs. mature; 87.63±3.24% normal head morphology; p<0.001) of the two populations differed significantly. After 2D electrophoresis, 16 differentially expressed protein spots were identified within the total sperm proteome between the immature and mature sperm populations. 56% of the differentially expressed proteins were more abundant in the immature sperm population compared to the mature sperm population. Functions have been ascribed to these proteins of which only four proteins, namely Tubulin -3C/D chain, Tubulin -2C chain, Outer dense fibre protein 2 and A-Kinase anchoring protein 4 precursor, were directly related to sperm motility and morphology. In the second part of the study the expression of nuclear proteins in human spermatozoa was investigated between immature and mature sperm populations. Semen was collected from healthy donors (n=156) and further separated from the seminal plasma by PureSperm® gradient centrifugation. The immature and mature sperm populations were retrieved and used during further analysis. For the proteomic analysis of nuclear proteins, cells were fractionated into four different subcellular protein fractions, instead of analyzing the whole sperm proteome. The results show that the motility (immature; 32.33±0.51% total motile cells vs. mature; 88.67±0.85% total motile cells; p<0.0001) and morphology parameters (immature; 13.51±0.87% normal head morphology vs. mature; 20.89±1.20% normal head morphology; p<0.0001) of the two populations differ significantly. After 2D electrophoresis, 21 differentially expressed nuclear proteins were identified between the immature and mature sperm populations. 95% of the differentially expressed nuclear proteins were less abundant in the immature population compared to the mature population. Only one nuclear protein namely 78kDa Glucose regulated protein was more abundant in the immature population compared to the mature population. Functions ascribed to these individual proteins were directly related to sperm motility, morphology and energy metabolism. In conclusion,In conclusion, in the current study novel techniques have been employed to investigate protein differences between immature and mature sperm populations. From these results it is evident that protein expression in the total sperm proteome and nuclear protein fraction is significantly different and incomplete in the immature population, compared to mature population. Based on these findings, it is recommended that further studies should be done on human spermatozoa to validate the role of the individual proteins in sperm function. Proteomics is an ideal tool to identify idiopathic causes of male infertility, as it can help to identify novel receptors (and signal transduction pathways) that can be used in the screening of drugs to alleviate sperm dysfunction. / AFRIKAANSE OPSOMMING: Manlike infertiliteit word dikwels geassosieer met verlaagde sperm motiliteit en morfologie (asthenoteratozoospermia) waarvoor daar tot dusver nog geen spesifieke terapeutiese behandeling is nie. Dit het aan die lig gekom dat die modifisering en uitdrukking van menslike sperm proteïene ‘n belangrike rol speel in spermfunksie. In die huidige studie stel ons data voor van proteiene in menslike sperme in die konteks van abnormale spermfunksie. Unieke tegnieke was gebruik om verskille in proteïen uitdrukking op sellulêre vlak suksesvol te isoleer en identifiseer wat verband hou met asthenoteratozoospermia. Tydens die eerste deel van die studie was verskille in proteïen uitdrukking binne die totale spermproteoom tussen onvolwasse en volwasse spermpopulasies ondersoek. Sperme van gesonde skenkers (n=23) is geskei in twee spermpopulasies (onvolwasse en volwasse sperme) deur middel van ‘n 3-laag Percoll gradiënt sentrifugasie tegniek. Selle is gewas en sperm motiliteit en morfologie is gemeet deur rekenaar geassisteerde sperm analise (CASA). Vir proteomiese analise is selle geliseer en proteïene geskei deur twee dimensionele gel elektroforese (2D-elektroforese). PD-Quest sagteware is gebruik om statisties beduidende proteïen verskille aan te dui. Die proteïene van belang is uitgesny en onderwerp aan in-gel vertering. Peptiede is geskei met behulp van hoë druk vloeistof chromatografie (HPLC) analise en aminosuurvolgordes is bepaal deur massa spektrofotometrie. Proteïene is geïdentifiseer met behulp van Mascot deur van die Swiss Prot databasis gebruik te maak. Die resultate toon dat die sperm motiliteit (onvolwasse; 26.1±1.75% totale motiele selle vs. volwasse; 60.93±3.24% totale motiele selle; p <0,001) en morfologiese parameters (onvolwasse; 64.1±2.75% normale kop morfologie vs. volwasse; 87.63±3.24% normale kop morfologie; p <0,001) tussen die twee populasies beduidend verskil. Na 2Delektroforese is 16 proteïen kolle geïdentifiseer wat beduidend verskil het, tussen die totale sperm proteoom van onvolwasse spermpopulasies en volwasse spermpopulasies. 56% van die proteïene wat beduidend verskil het, was meer uitgedruk in die onvolwasse spermpopulasie ten opsigte van die volwasse sperm populasie. Funksies is toegeskryf aan hierdie proteïene waarvan net vier proteïene naamlik Tubulin -3C/D ketting, Tubulin -2C ketting, Buite digte vesel proteïen 2 en A-Kinase anker proteïen 4 voorloper direk verband hou met sperm motiliteit en morfologie. In die tweede deel van die studie is die uitdrukking van nukluêre proteïene in menslike spermatozoa tussen onvolwasse en volwasse spermpopulasies ondersoek. Sperme was van gesonde skenkers (n=156) versamel en verder geskei van seminale plasma deur middel van ‘n PureSperm® gradiënt sentrifugasie tegniek. Vir die proteomiese analise van nukluêre proteïene is selle gefraksioneer in vier verskillende sub-sellulêre proteïen fraksies, in plaas van analise van die totale spermproteoom. Die resultate toon aan dat die sperm motiliteit (onvolwasse; 32.33±0.51% totale motiele selle vs. volwasse; 88.67±0.85% totale motiele selle; p <0,001) en morfologiese parameters (onvolwasse; 13.51±0.87% normale kop morfologie vs. volwasse; 20.89±1.20% normale kop morfologie; p <0,001) tussen die twee populasies beduidend verskil. Na 2D-elektroforese is 21 kern proteïen kolle geïdentifiseer wat betekenisvol uitgedruk was tussen onvolwasse en volwasse spermpopulasies. 95% van die nukluêre proteïene wat beduidend verskil het, was minder uitgedruk in die onvolwasse spermpopulasie ten opsigte van die volwasse spermpopulasie. Slegs een kern proteïen naamlik 78kDa Glukose gereguleerde proteïen was meer uitgedruk in die onvolwasse spermpopulasie in vergelyking met die volwasse spermpopulasie. Funksies is toegeskryf aan hierdie proteïene wat direk verband hou met sperm motiliteit, morfologie en energie metabolisme. Ten slotte, in die huidige studie is unieke tegnieke geïmplementeer om proteïen verskille tussen onvolwasse en volwasse spermpopulasies te ondersoek. Uit hierdie resultate is dit duidelik dat proteïen uitdrukking in die totale sperm proteoom en in die kern proteïen fraksie beduidend verskil en onvolledig is in die onvolwasse spermpopulasie ten opsigte van die volwasse spermpopulasie. Op grond van hierdie bevindinge word aanbeveel dat verdere studies op menslike sperme gedoen moet word ten einde die rol van individuele proteïene in sperm funksie te kan bepaal. Proteomika is ‘n ideale tegniek om die iodiopatiese oorsake van manlike infertiliteit te identifiseer, aangesien dit kan help in die identifisering van unieke reseptore (en seintransduksie paaie) wat gebruik kan word om sperm disfunksie te verbeter deur farmaseutiese behandeling.

No description available.

published_or_final_version / Sports Science / Master / Master of Science in Sports Science

This study examined the effect of vitamin B-6 supplementation and exhaustive submaximal exercise on plasma catecholamine concentrations, and the relationship between plasma catecholamines and fuel use, heart rate and oxygen consumption. Five trained men (age= 18-35 years; V0₂max=53 ml 0₂/kg/min.) participated in two controlled dietary periods that were identical except for the addition of 20 mg/d pyridoxine (PN) supplementation during the second period. On the seventh morning of each period, fasted subjects exercised to exhaustion on a cycle ergometer at 74.5% ± 7.8 V0₂max. Blood was drawn pre-exercise (twice), 60 minutes into exercise, immediately post-exercise and 60 minutes post-exercise. Plasma was analyzed for norepinephrine, epinephrine, glucose, pyridoxal 5'-phosphate (PLP), lactic acid, glycerol and free fatty acids (FFA). Heart rate and oxygen consumption were measured pre-exercise and at 10-minute intervals during exercise. Mean plasma PLP concentration was significantly higher during the supplemented versus the nonsupplemented trial at all time points. There were no statistically significant differences in mean plasma catecholamine concentrations or mean plasma fuel concentrations between the nonsupplemented and supplemented trials at any of the time points examined. There were significant changes in the mean plasma concentrations of norepinephrine, lactic acid, glycerol and FFA over time in both trials. Respiratory exchange ratios (R) were higher during the supplemented trial compared to the nonsupplemented trial, but the differences did not attain statistical significance. There were no significant differences in mean exercise times to exhaustion or mean heart rates between the trials. The overall mean oxygen consumption during exercise was consistently higher during the supplemented versus the nonsupplemented trial and the difference attained significance (p=0.016) at one time point (10 min.). The mean oxygen consumption during rest was lower during supplementation versus nonsupplementation, but the difference was not statistically significant. The percent plasma volume change (PVC) was significantly greater at post-exercise, relative to pre-exercise, during the supplemented versus the nonsupplemented trial. The percent PVC also increased significantly over time during the supplemented but not the nonsupplemented trial. These results suggest that 20 mg/d of vitamin B-6 supplementation does not effect plasma catecholamine concentrations, fuel utilization or heart rate at rest or during submaximal exercise to exhaustion. The results may suggest a higher oxygen consumption during exhaustive exercise after PN supplementation. / Graduation date: 1996