摘要:

Abstract31P NMR spectroscopy provides a means of monitoring intracellular pH (pHi). In order to determine the significance of observed pH changes, an assessment of the measurement uncertainty is required. This paper considers the possible sources of error involved, firstly in chemical shift assignment and, secondly, in relating chemical shift to pH. A statistical analysis of these errors is presented and an expression for the accuracy of pH measurements obtained usingin vivo31P NMR spectroscopy is derived. Computer simulations and clinical measurements are considered to determine the likely error in clinical measurements. A comparison of pH measurement methodology using a centre‐of‐gravity calculation, Gaussian and Lorentzian fitting is also presented and discus

ISSN:0952-3480    

DOI:10.1002/nbm.1940040102

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe progression of carbon tetrachloride‐induced liver damage, determined by31P NMR spectroscopy, was compared with selected serum enzyme and histological changes in rats. ATP levels declined as early as 8 h post‐CCI4administration, with partial recovery observed at 168 h. The results show that ATP reduction correlates with necrosis. In addition, early decline in ATP occurring prior to significant hepatocellular necrosis indicates abnormal energy metabol

ISSN:0952-3480    

DOI:10.1002/nbm.1940040103

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractAdriamycin induced cardiotoxicity is, among other factors, characterized by an impairment of mitochondrial function and altered energy metabolism. The possible merits of31P NMR in timely detection of this cardiotoxicity were studied in perfused hearts of chronically treated rats after cumulative doses of 6,8,10,12 and 13 mg adriamycin/kg body wt and compared to histological evaluation. After high cumulative doses the Phosphocreatine (PCr)/ATP ratio was significantly decreased in the hearts of treated animals, compared to the control animals (1.65±0.13 vs. 2.47±0.36 (p<0.001) at 12 mg/kg and 1.92 ± 0.22 vs. 2.37±0.15 (p<0.01) at 13 mg/kg adriamycin, respectively). This decrease coincides with a sudden increase in the histological score from 2.0 at 10 mg/kg to 8.0 at 12 mg/kg adriamycin on a scale of 10.0. The Pi/PCr ratio, coronary flow and rate pressure product (RPP) of the isolated hearts of treated animals were not significantly different from controls. When heart rates were increased, parallel changes in PCr/ATP ratio, Pi/PCr ratio, RPP and coronary flow were observed in both control and treated groups, except for the 12 mg/kg adriamycin group in which pacing failed to increase RPP. In addition, in this group the Pi/PCr ratio at higher heart rates was significantly increased (p<0.001) compared to controls. At 13 mg/kg similar effects were observed but less pronounced. The decreased PCr/ATP ratio may indicate an increased ADP concentration and altered regulation of energy metabolism. Differences between control and treated groups in RPP and Pi/PCr ratio during pacing may also be related to cardiotoxicity. The results of this study show that changes in energy metabolism in the heart during chronic adriamycin treatment may well be observed by31P NMR. Furthermore, they indicate that clinical31P NMR may be a suitable tool for monitoring the development of adriamycin induced cardiotoxicity, thereby avoiding the disadvantages of invasive procedu

ISSN:0952-3480    

DOI:10.1002/nbm.1940040104

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effect of anaerobic metabolic changes on the flux of the creatine kinase reaction in bullfrog skeletal muscle was evaluated by31P saturation transfer NMR. During an anaerobic time course the reduction ratio (M+/M0) of the phosphocreatine signal and the spin‐lattice relaxation time measured in the presence of saturating irradiation at the ATP γ‐phosphate resonance were decreased; however, the intrinsic spin‐lattice relaxation time of phosphocreatine was constant (4 s). The pseudo‐first‐order rate constant for the forward reaction of creatine kinase (i.e., phosphocreatine to ATP) was increased during the time course, accompanied by a decrease in phosphocreatine concentration and an intracellular acidification. However, the flux was constant (4 mmol . kg−1wet wt . s−1) over the anaerobic time course. The fluxes analysed in several locations along the fibers, which were simultaneously measured by means of the one‐dimensional chemical shift imaging technique, were almost the same along the entire length of the fibers. These results indicate that the creatine kinase reaction is at equilibrium along the entire length of the fr

ISSN:0952-3480    

DOI:10.1002/nbm.1940040105

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractUsingin vivo1H NMR spectroscopy (1H MRS) and biochemical analysis, the effects of hyperammonemia on cerebral function were studied in three rat models: acute liver ischemia (LIS), administration of urease (UREASE) and administration of methionine sulfoximine (MSO). By means of localization in three dimensions signals were obtained exclusively from the cerebral cortex. Specially developed lineshape correction and fitting methods were used to quantitate the MRS signals. The following concentration changes were observed; a decrease in glutamate and (phospho) choline for all the models; an increase in glutamine in the LIS and UREASE model but a decrease in the MSO model; a marked increase in lactate in the LIS and UREASE group; a tendency to a decrease inN‐acetylaspartate in all the models. These changes agree well with the changes in the post‐mortem biochemically determined cerebral cortex glutamine and glutamate concentrations. Estimated absolute1H MRS metabolite concentrations agree well with those obtained by other techniques; cerebral cortex glutamate, however, is underestimated by about 35% by NMR. The present data support the hypothesis that hyperammonemia is associated with a decreased availability of glutamate for neurotransmiss

ISSN:0952-3480    

DOI:10.1002/nbm.1940040106

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

Abstract31P and 3‐fluoro‐3‐deoxy‐D‐glucose (3‐FDG)19F nuclear magnetic resonance (NMR) spectroscopic investigations were performed on aged rat brainin vivo. Phosphodiester (PDE) was found to be significantly higher (p<0.05) in aged brain (18 months,n= 10) than adult controls (6 months,n= 10) suggesting accelerated phospholipid catabolism in aged brain. Inorganic phosphate (P,) levels were significantly lower (p<0.05) in aged brain (n= 5) than in normal adult controls (5= 5). The sorbitol index, a measure of aldose reductase activitiesin vivo, determined by the 3‐FDG19F NMR method, revealed that aldose reductase activities were significantly higher (p<0.05)

ISSN:0952-3480    

DOI:10.1002/nbm.1940040107

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe calf muscle metabolism of 7 patients with stable chronic respiratory failure (PaO2below 65 Torr) was studied using31P NMR spectroscopy. NMR spectra were acquired at rest, during the course of 360 pedal movements at 20, 35 and 50% of the maximal voluntary contraction (MVC) and during recovery. Eight normal aged‐matched subjects served as a control group. In resting muscle, no significant differences were observed between both groups as regards intracellular pH, inorganic phosphate/phosphocreatine (Pi/PCr) and β‐ATP/PCr + Pi + phosphomonoester (PME) ratios. Although effective power outputs were similar for both groups at each work level, patients exhibited a higher Pi/PCr ratio than healthy controls (3.19 ± 1.01 vs 0.49 ± 0.05 at 50% MVC;p<0.01) and a lower pHi(6.65 ± 0.11 vs 7.06 ± 0.02 at 50% MVC;p<0.01). Moreover, PCr resynthesis during recovery was slower in patients than in control subjects (t1/2PCr = 1.26 ± 0.30 vs 0.47 ± 0.05 min;p= 0.01). These results suggest impairment of aerobic capacity in a non‐ventilatory working muscle, probably due to hypoxemia in patients with chronic respira

ISSN:0952-3480    

DOI:10.1002/nbm.1940040108

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940040101

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY