摘要:

AbstractPattern recognition has been applied to the analysis ofin vivo31P 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 entire31P spectrum were required for best separation of the tumour and tissue classes.

ISSN:0952-3480    

DOI:10.1002/nbm.1940060402

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSpectral editing experiments were used to quantify CH3groups from macromolecular species in the chemical shift region from 1.2 to 1.4 ppm of rat cerebrumin 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) thanN‐acetyl aspartate (NAA) and shorterT2[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 asin vivo.These data show that the macromolecular peaks in the brain atTE>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

ISSN:0952-3480    

DOI:10.1002/nbm.1940060403

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this study we compared the kinetics of phosphocreatine (PCr) and Pirecovery, 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 Pirecovery almost overlapped when the lowest value of cytosolic pH reached during recovery (termed the minimum pH) was6.95. This result is interpreted as indirectin vivoevidence 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.

ISSN:0952-3480    

DOI:10.1002/nbm.1940060404

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractHigh‐resolution31P 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 the31P 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 ofin vitro vs in vivospectra, and for the interpretation of effect

ISSN:0952-3480    

DOI:10.1002/nbm.1940060405

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe metabolism of [1,2‐13C2]glucose and [U‐13C4]3‐hydroxybutyrate was studied in rat brain within vivoandin vitro13C NMR spectroscopy, taking advantage, in particular, of homonuclear13C‐13C spin coupling patterns. After infusion of [1,2‐13C2]glucose or [U‐13C4]3‐hydroxybutyrate into rats, the uptake of the substrates in brain and their metabolism to [1‐13C]bicarbonate could be detected within vivo13C NMR spectroscopy. At the end of the infusion experiment, methanol/HCI/HCIO4extracts of the brain tissue were further analysed by high resolution13C NMR spectroscopy. The13C spin coupling patterns revealed entirely different isotopomer distributions for the closely related cerebral metabolites glutamate, glutamine and 4‐aminobutyric acid. A quantitative analysis of the13C spectra demonstrated (i) the existence of two kinetically distinct pools of glutamate, (ii) a pronounced CO2fixation via pyruvate carboxylase in the glial cells accounting for as much as 38% of the oxaloacetate synthesis in the glial tricarboxylic acid cycle, (iii) a cerebral pyruvate recycling system contributing maximally 17% of the pyruvate metabolism through the pyruvate dehydrogenase in neurons, and (iv) a predominant production of 4‐aminobutyric acid from glutamate synthesized in the neurons. In addition, the labelling pattern ofN‐acetyl aspartate upon infusion of labelled glucose or 3‐hydroxybutyrate provided insight into the synthesis of this compound in mammalian brain. While the acetyl moiety originates from the metabolic equivalent of the C‐1–C‐2 part of cerebral glutamate, the aspartyl moiety is not in direct contact with the intermediates of glycolysis or of

ISSN:0952-3480    

DOI:10.1002/nbm.1940060406

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractWe have measured, directly and simultaneously, changes in extracellular volume and intra‐ and extracellular pH during ischemia in the isolated rat heart using31P NMR spectroscopy. Hearts were perfused with buffer containing 15 mM sodium phenylphosphonate at pH7.4. Wash in and wash out experiments showed that phenylphosphonate entered only the extracellular (interstitial, vascular and chamber) space of the heart and had no adverse effects on myocardial energetics, contractile function or coronary flow rate. Hearts were subjected to 28 min of total, global ischemia, during which the phenylphosphonate resonance area in the31P NMR spectra decreased by 83%, indicating that extracellular fluid had moved rapidly from the heart to the bath surrounding the heart, partly as a result of vascular collapse. A separate, morphological study confirmed that 95% of the vasculature had collapsed by 28 min ischemia. Intra‐ and extracellular pH were determined from the chemical shifts of the Piand the phenylphosphonate resonances, respectively. In the pre‐ischemic rat heart, intracellular pH was 7.15±0.03 and extracellular pH was 7.39±0.03. By 4 min of ischemia, intra‐ and extracellular pH were the same and decreased concomitantly throughout the remainder of ischemia to final values of 6.09±0.19 and 6.16±0.23, respectively. On reperfusion, the extracellular volume and pH returned to pre‐ischemic levels within 1 min, but restoration of intracellular pH took>2.5 min. Thus, a large volume of extracellular fluid moves out of the rat heart to the surrounding bath and the intra‐ and extracellular pH become the same during total,

ISSN:0952-3480    

DOI:10.1002/nbm.1940060407

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940060408

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940060401

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY