bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bulk magnetic susceptibility induced broadening in the 19F NMR of suspended leukemic cells
Authors: Adebodun Foluso , Post Jan F. M. 
Published: March 2007

AbstractThe relevance of bulk magnetic susceptibility (BMS) induced broadening to in vivo NMR studies of intact cells has been examined and the significance of the contribution of BMS difference to the resolution of intra‐ and extracellular resonances was demonstrated. BMS difference between intra‐ and extracellular compartments was found to limit the resolution of intra‐ and extracellular 19F resonances of fluoro compounds in leukemic cells.
Transmembrane 19F NMR chemical shift difference of fluorinated solutes in liposomes, erythrocytes and erythrocyte ghosts
Authors: Xu Arron S. L. , Waldeck A. Reginald , Kuchel Philip W. 
Published: March 2007

AbstractIn erythrocytes suspended in isotonic medium, a number of fluorinated anions showed well resolved 19F NMR resonances from the solute populations in the intra‐ and extracellular compartments; the intracellular resonances were shifted to higher frequency (low field). In addition 19F NMR resonances of extracellular solutes were shifted to higher frequency when bovine serum albumin was incorporated into the extracellular medium. The dependence of 19F NMR chemical shift on protein concentration was also demonstrated using resealed red cell ghosts and liposomes; in the presence of external hemoglobin, lysozyme and bovine serum albumin, the shift of the external resonances was to higher frequency. In addition, significant high frequency shifts of 19F NMR resonances were evident along with an increase of temperature. The results of the present study further support the contention that the principal physical basis for the shifts is the disruption of direct hydrogen bonds between 19F of the solutes and (primarily) solvent H2O by protein hydration. The ‘split peak’ phenomenon is of general importance in biological systems where a transmembrane protein‐concentration difference exists.
Biological applications for small solenoids: NMR spectroscopy of microliter volumes at high fields
Authors: Wiseman Robert W. , Moerland Timothy S. , Kushmerick Martin J. 
Published: March 2007

AbstractIn this paper we describe features of an NMR probe designed for the study of small, superfused muscles. We also present the results of an empirical study of the performance characteristics of several configurations of small solenoid coils, ca 2 mm diameter. Our data show that optimal use of the available volume of sample becomes the prime consideration in coil design at this scale. In contrast to large biological samples, for such small coils the equivalent resistance associated with the sample is minor relative to the resistance of the RF coil itself. Thus, substantial improvements in the S/N ratio can be obtained by adopting coil configurations that are inferior electrically, but which can sample a greater volume of tissue.
Effects of fish oil on phospholipid metabolism in human and rat liver studied by 31P NMR spectroscopy in vivo and in vitro
Authors: Dagnelie Pieter C. , Bell Jimmy D. , Cox I. Jane , Menon David K. , Sargentoni Janet , Coutts Glyn A. , Williams Steve C. R. 
Published: March 2007

AbstractThe effect of ω3 fatty acids on the metabolism of the normal liver was studied using 31P NMR spectroscopy. Human subjects were examined before and after 1, 3 and 7 days of supplementation with 50 mL fish oil per day (12 g ω3 fatty acids). 31P NMR spectra (1.6 T) revealed a significant increase in phosphodiester (PDE) to ATP ratios after 1 and 3 days of fish oil. After 7 days, [PDE]/[ATP] ratios at a TR of 1 s had returned to baseline levels, but [PDE]/[ATP] at a TR of 5 s appeared to remain high. Rats were fed diets containing 50% of the energy from fish oil or normal rat chow (controls) for 14 days. 31P NMR liver spectra in vivo (4.7 T) confirmed increased [PDE]/[ATP] in rats fed fish oil compared to controls, although the difference was only statistically significant at a TR of 1.5 s but not at a TR of 8s. 31P NMR spectra of rat liver extracts (8.7 T) suggested that increased concentrations of glycerophosphocoline and possibly glycerophosphoethanolamine were responsible for rising PDE levels in vivo. Phosphocholine (PC) concentrations were markedly reduced in rat liver after fish oil. The combined rise in glycerophosphocholine and reduction in PC would be consistent with a shift from the phospholipase C to the phospholipase A1/A2 pathway of phosphatidylcholine breakdown after fish oil consumption.
NMR spectroscopy of human post mortem cerebrospinal fluid: Distinction of Alzheimer's disease from control using pattern recognition and statistics
Authors: Ghauri Farida Y. K. , Nicholson Jeremy K. , Sweatman Brian C. , Wood John , Beddell Christopher R. , Lindon John C. , Cairns Nigel J. 
Published: March 2007

Abstract1H NMR spectra have been measured at 500 and 600 MHz on 23 human cerebrospinal fluid samples obtained at autopsy from Alzheimer's disease patients and controls. The spectra at 500 MHz were quantified using 42 descriptors based on NMR peak heights and it was shown that differences between the two classes were apparent in the δ2.4–2.9 region. Remeasured at 600 MHz a detailed examination of this chemical shift range identified citrate, aspartate, N‐acetyl aspartate, methionine and glutamate in this region of the spectra. Principal components analysis showed that a separation of the two classes was possible and detailed statistics indicated that citrate level was the principal marker. Patient age and the interval between death and autopsy (parameters not closely matched between the two groups) were examined statistically to establish whether these might account for the citrate differences. Although they could possibly account for them to some extent, the relationship between citrate levels and disease state remained significant at p<0.05. The data invite a test of the importance of citrate levels in Alzheimer's disease using samples taken ex vivo.
Controllable graded cerebral ischaemia in the gerbil: Studies of cerebral blood flow and energy metabolism by hydrogen clearance and 31P NMR spectroscopy
Authors: Allen K. L. , Busza A. L. , Proctor E. , King M. D. , Williams S. R. , Crockard H. A. , Gadian D. G. 
Published: March 2007

AbstractA technique for remotely controlling the degree of carotid artery occlusion in the gerbil model of cerebral ischaemia has been developed. The technique relies on manually adjustable nylon snares around the carotid arteries, in conjunction with a computer‐based monitoring system, to control the degree of occlusion. This has allowed us to determine the dependence of energy metabolism (as assessed by 31P NMR spectroscopy) on blood flow in greater detail than was possible in our previous studies. Data obtained show that energy changes first appear at flows of 25–30 mL/100 g/min, while at flows below 20 mL/100 g/min there is a major derangement of energy metabolism. The model was used to determine the sensitivity of cerebral energy metabolism to reduced cerebral blood flow under normothermic conditions and in mild hypothermia (30°C). Hypothermia had a protective effect in that energy metabolites were maintained at flows significantly below the normothermic threshold.
Experimental allergic encephalomyelitis raises betaine levels in the spinal cord of strain 13 guinea‐pigs
Authors: Preece N. E. , Baker D. , Butter C. , Gadian D. G. , Urenjak J. 
Published: March 2007

AbstractChronic relapsing experimental allergic encephalomyelitis, an animal model of multiple sclerosis, was induced in Strain 13 guinea‐pigs by subcutaneous injection of spinal cord homogenate and Freund's incomplete adjuvant supplemented with Mycobacterium tuberculosis. High resolution 1H NMR spectra of CNS tissue extracts indicated that the levels of choline metabolites, particularly betaine, were elevated in the spinal cord tissue, the principal site of lesion formation in this guinea‐pig strain. The spectra also show that N‐acetylated compounds are slightly depleted in the disease. The results are discussed in relation to the biochemical interpretation of NMR spectra obtained in vivo from patients with multiple sclerosis.
A comparative study of 1H NMR lineshape fitting analyses and biochemical lipid analyses of the lipoprotein fractions VLDL, LDL and HDL, and total human blood plasm
Authors: Ala‐Korpela M. , Hiltunen Y. , Jokisaari J. , Eskelinen S. , Kiviniitty K. , Savolainen M. J. , Kesäniemi Y. A. 
Published: March 2007

AbstractThe purpose of this work was two‐fold. In the first instance, 1H NMR spectra of the ultracentrifuged lipoprotein fractions (VLDL, LDL and HDL) from six volunteers with different clinical conditions were measured. The methylene regions of the experimental spectra were modelled in the frequency domain using non‐linear lineshape fitting analyses. In this way the resolvable Lorentzian component structures of the methylene regions of these lipoprotein fraction spectra could be determined. Second, the lipoprotein fraction analyses were used to construct simplified component structures, which interpreted the lipoprotein fraction spectra well, and were feasible to use in the total plasma spectra analyses. The considerable overlap problem of the resonances was properly handled in this way. The NMR‐based relative amounts of the lipoproteins (relative integrated intensities of the lipoprotein model signals) obtained were compared to the biochemically resolved relative molar percentages of the lipoprotein fractions and also of the lipid contents between the lipoprotein complexes. It was noticed that nearly all correlations were extremely good. Thus, it is suggested that the developed methodology could be used as a fast method to predict the relative amounts of the lipoproteins and also possibly the relative lipid contents between the major lipoprotein categories directly from the proton NMR spectrum of a total blood plasma sample. Furthermore, if internal or external reference for the integrated intensities of the proton NMR resonances were used, it should also be possible to obtain the absolute amounts of these quantities.
Pattern recognition of 31P magnetic resonance spectroscopy tumour spectra obtained in vivo
Authors: Howells S. L. , Maxwell R. J. , Howe F. A. , Peet A. C. , Stubbs M. , Rodrigues L. M. , Robinson S. P. , Baluch S. , Griffiths J. R. 
Published: March 2007

AbstractPattern recognition has been applied to the analysis of in vivo 31P NMR spectra. Using four different classes of tumour and three types of normal tissue, cluster analysis and artificial neural networks were successful in separating and classifying the majority of samples analysed. Although the phosphomonoester and Pi, regions appeared to be the most important spectral features, data representing the entire 31P spectrum were required for best separation of the tumour and tissue classes.
Quantitative analysis of 1H NMR detected proteins in the rat cerebral cortex in vivo and in vitro
Authors: Kauppinen Risto A. , Niskanen Timo , Hakumäki Juhana , Williams Stephen R. 
Published: March 2007

AbstractSpectral editing experiments were used to quantify CH3 groups from macromolecular species in the chemical shift region from 1.2 to 1.4 ppm of rat cerebrum in vivo. Two peaks centred at 1.22 and 1.40 ppm were revealed when irradiation was positioned at 4.35 or 4.30 ppm. These peaks had lower saturation factors (1 vs. 1.72±0.10) than N‐acetyl aspartate (NAA) and shorter T2 [60±5.8 (1.22 ppm) and 51±2.2 (1.40 ppm) vs. 123±12 (NAA) ms]. The concentrations of the peaks at 1.22 and 1.40 ppm were calculated to be 0.65±0.09 and 1.37±0.18 mmol of CH3, equivalents/kg brain. Acid extract from cerebral corticies contained macromolecular peaks at the same chemical shifts with approximately the same area ratios to NAA as in vivo. These data show that the macromolecular peaks in the brain at TE>100 ms arise predominantly from proteins which are acid soluble. The assignment of macromolecular signals in the cerebral spectrum to a given polypeptide (thymosin β4 and histone H1) is discussed in the light of protein analyses of brain acid extracts.
in vivo assessment of mitochondrial functionality in human gastrocnemius muscle by 31P MRS. The role of pH in the evaluation of phosphocreatine and inorganic phosphate recoveries from exercise
Authors: Iotti S. , Lodi R. , Frassineti C. , Zaniol P. , Barbiroli B. 
Published: March 2007

AbstractIn this study we compared the kinetics of phosphocreatine (PCr) and Pi recovery, and their dependency on cytosolic pH in 38 normal individuals. Spectra were acquired during rest, work and recovery. A time resolution of 10 s was used to obtain detailed information. The kinetics of PCr and Pi recovery almost overlapped when the lowest value of cytosolic pH reached during recovery (termed the minimum pH) was <6.95, while they were completely dissociated when the minimum pH was >6.95. This result is interpreted as indirect in vivo evidence of the kinetic control exerted by ADP on mitochondrial oxidation. Our results represent a rationale for new experimental conditions to be used in clinical routine studies of pathologies due to primary or secondary mitochondrial malfunction.
The influence of medium formulation on phosphomonoester and UDP‐Hexose levels in cultured human colon tumor cells as observed by 31P NMR spectroscopy
Authors: Shedd Suzanne F. , Lutz Norbert W. , Hull William E. 
Published: March 2007

AbstractHigh‐resolution 31P NMR spectroscopy at 11.7 T was used to examine the influence of medium formulation (medium and serum type, and concentrations of glucose and inositol) on the cellular phosphate metabolism of CX‐1 cells, a human colon cancer cell line derived from HT‐29 cells. Striking differences in the 31P spectra of harvested CX‐1 cells were observed. The largest variation was seen in the phosphocholine and UDP‐hexose levels (up to seven‐fold changes), with smaller differences in the levels of other phosphate metabolites. The major UDP‐hexose species were found to be UDP‐N‐acetylglucosamine and UDP‐N‐acetylgalactosamine (ca 2:1 ratio), which have been proposed in the literature to be markers of cell differentiation status. Medium‐induced alterations in metabolite levels were much greater than the normal variations seen in CX‐1 control samples grown under identical conditions. They even exceeded the characteristic differences observed between different human tumor cell lines grown under one set of culture conditions. The remarkable sensitivity of CX‐1 cellular phosphate metabolism to the culture environment has implications for the comparison of in vitro vs in vivo spectra, and for the interpretation of effects due to growth and therapy.
In vivo19F NMR studies of hyperthermia: Hydrophobic environments probed by halothane
Authors: Burt C. T. , Moore R. R. , Roberts M. F. 
Published: March 2007

AbstractThe steady‐state distribution of the general anesthetic halothane in different rat tissues, including a renal adenocarcinoma with and without hyperthermia treatment, has been evaluated by In vivo 19F NMR spectroscopy. The 19F spectra of halothane (which is a hydrophobic probe) from within tissue show differences in the partitioning between normal rat tissues and adenocarcinoma. Muscle, as a control tissue, exhibits a single large resonance around 0 ppm. However, the adenocarcinoma exhibits two slow‐exchanging resonances separated by 0.3 ppm with the one at the more hydrophobic chemical shift being more sensitive to hyperthermia treatment. The results from this tumor model suggest that 19F NMR spectroscopy may be useful first in detecting a change in hydrophobic environments using a lipophilic probe such as halothane, and secondly in monitoring the effects of hyperthermia, a treatment whose effectiveness may involve changes at the level of the plasma membrane. Under conditions of continuous delivery, a resonance which is not detected in the spectra of halothane in excised tissue appears 5 ppm downfield from the resonance for halothane localized in tissues. A rotating frame experiment is used to show that this resonance is derived from anesthetic absorbed on the tissue surface.
Growth and Magnetic Resonance Characteristics of Human Squamous Cell Carcinoma Xenografts Implanted with Cells Suspended in MatrigelTM
Authors: Czerski L. , Majors A. , Ng T. C. , Vijayakumar S. , Weichselbaum R. 
Published: March 2007

AbstractGrowth and magnetic resonance characteristics of a human squamous cell carcinoma SQ20B were studied in vivo as xenografts in nu/nu nude mice. Tumor cells injected subcutaneously in the flank using either MatrigelTM (MTG, an extract of basement membrane proteins) or growth medium (GM) as a vehicle were compared. Much higher tumor growth rates and cell density were observed with MatrigelTM than with GM implantation. Histology also showed that MTG implanted cells grew as vascularized solid tumors compared to GM tumors which formed cysts. As a result of increased cell density with the improved method, tumors as small as 0.3 cm3 provide high S/N magnetic resonance spectra which yield smaller standard deviations with fewer experiments.
Mapping of cerebral metabolites in rats by 1H magnetic resonance spectroscopic imaging. Distribution of metabolites in normal brain and postmortem changes
Authors: Higuchi Toshihiro , Fernandez Erik J. , Maudsley Andrew A. , Weiner Michael W. 
Published: March 2007

AbstractThe goal of this study was to examine metabolic differences between cortex and basal ganglia in normal rat brain and to determine postmortem changes using in vivo 1H magnetic resonance spectroscopic imaging at 300 MHz. The resonances observed were: choline, creatine+phosphocreatine, N‐acetyl aspartate (NAA), lactate (Lac), and three small resonances in the amino acid region which included resonances from aspartate + NAA (Asp), glutamine + NAA (Gln), and glutamate+GABA (Glu). A previously unassigned resonance was observed at 1.13 ppm in brain of rats anesthetized with pentobarbital. Spectroscopic images in normal brain demonstrated increased NAA and Gln and decreased Glu in cortex compared to basal ganglia. The major postmortem changes were an increase of Lac, Glu and Cho and a decrease of NAA and Asp. The rise in Lac was significantly higher in cortex than in basal ganglia.
Phospholipid metabolites, prognosis and proliferation in human breast carcinoma
Authors: Smith T. A. D. , Bush C. , Jameson C. , Titley J. C. , Leach M. O. , Wilman D. E. V. , McCready V. R. 
Published: March 2007

AbstractThe content of the phospholipid metabolites, phosphocholine, phosphoethanolamine, glycerophosphorylcholine and glycerophosphorylethanolamine was measured in chemical extracts from 46 human breast carcinoma using 31P NMR spectroscopy. Some patients had received therapy prior to tumour resection. The data were therefore stratified into two groups: (i) all tumours; and (ii) untreated tumours. Three indices of tumour proliferation i.e., mitotic index, Ki67 and S‐phase fraction were determined on tissue from the same tumours and were found not to correlate with the content of any of these metabolites. In addition oestrogen‐receptor status and density, tumour grade and DNA ploidy were obtained on some tumours. The phosphocholine content was higher in high grade tumours when compared with low grade tumours. There was no apparent relationship between DNA ploidy and the content of any of these metabolites. Glycerophosphorylcholine content of oestrogen‐receptor positive tumours correlated with receptor density. However, there was no significant difference between receptor positive and negative tumours in the content of any of the phospholipid metabolites measured.
Application of high field localised in vivo1H MRS to study biochemical changes in the thiamin deficient rat brain under glucose load
Authors: Rose S. E. , Nixon P. F. , Zelaya F. O. , Wholohan B. T. , Zimitat C. , Moxon L. N. , Crozier S. , Brereton I. M. , Doddrell D. M. 
Published: March 2007

AbstractIn vivo, volume‐selected 1H NMR spectroscopy employing the SPACE technique was used to monitor biochemical changes in the thiamin deficient rat brain in response to glucose loading. The concentrations of brain N‐acetylaspartate, glutamate/glutamine/γ‐aminobutyric acid, lactate and glucose differed significantly from those of control animals. The results are consistent with a metabolic block at the reaction catalyzed by the thiamin dependent enzyme α‐keto glutarate dehydrogenase soon after the onset of neurological symptoms of thiamin deficiency, and a further block at pyruvate dehydrogenase arising late in the course of thiamin deficiency.
In vivo31P MRS of experimental tumours
Authors: de Certaines J. D. , Larsen V. A. , Podo F. , Carpinelli G. , Briot O. , Henriksen O. 
Published: March 2007

AbstractMore than 50% of cancers fail to respond to any individual treatment and tumour follow‐up after treatment plays a major role in routine therapy planning and pharmacological research. Today, MRS is the only technological approach providing non‐invasive access to tumour biochemistry. Ten years ago, expectations were raised concerning 31P MRS as an exciting and promising technical approach to the study of tumours. However the expectations have not always come to fruition. How close are we now to seeing routine 31P NMR in clinical oncology? This review of the 127 published papers shows spectroscopy results in more than 150 experimental animal tumour models. These tumour/host/treatment systems provide us with a useful basis to evaluate the current state of the art, summarize the basic knowledge presently available, determine the key points underlying the present disappointment of some clinical oncologists and stimulate new basic research. The information collected concerns the discussion of the reliability of experimental models in oncology, the technical improvement of magnetic resonance technology and the monitoring of bioenergetic status, pH regulation and phospholipid metabolism in treated and untreated tumours. Recent advances (two‐thirds of the papers have been published in the last 5 years) seem to provide more optimistic perspectives than those generally accepted a few years ago, in the depressing period following early pioneering work.
Spin‐echo and gradient‐echo epi of human brain activation using bold contrast: A comparative study at 1.5 T
Authors: Bandettini Peter A. , Wong Eric C. , Jesmanowicz A. , Hinks R. Scott , Hyde James S. 
Published: March 2007

AbstractIn this study, Blood Oxygenation Level Dependent (BOLD) contrast in the detection of human brain activation was compared between spin‐echo and gradient‐echo echo‐planar sequences at 1.5 T. Time course series of spin‐echo and gradient‐echo images containing the primary motor cortex were collected during rest (no finger movement) and activation (finger movement). Each time course series was collected using a different TE. Resting and active state signal intensities at each TE were measured in identical regions in the motor cortex. From these data, resting and active state R2 (1/T2) and R (1/T) values were obtained. Across four subjects, brain activation produced an average R2 change of −0.16±0.02/s (±SE), and an average R change of −0.55±0.08/s. The average ΔR/ΔR2 ratio was 3.52±0.56. The average gradient‐echo/spin‐echo ratio of activation‐induced signal changes at the TE for maximal BOLD contrast for each sequence (TE≈T and T2) was calculated to be 1.87±0.40.