摘要:

AbstractThe effects of two widely used paramagnetic shift reagents for cationic NMR, dysprosium tripolyphosphate [Dy(PPP)27−] and dysprosium triethylenetetramine hexaacetate [Dy(TTHA)3−], on the cell structure of dog and human erythrocytes, dog kidney cortical tubules and rat hepatocytes were investigated. The effect of shift reagents on cell integrity was monitored by measuring the hematocrit values for erythrocytes, by measuring the lactate dehydrogenase (LDH) release and by electron microscopy for cortical tubules and hepatocytes. The quantitation of the dyprosium penetration inside cells was accomplished by atomic absorption, atomic emission and neutron activation. More severe effects were observed with Dy(PPP) 27−than with Dy(TTHA)3−, and were dependent on the divalent cation concentration and on the shift reagent concentration. Very serious cell damage was observed after 60 min incubation in the presence of 10 μmol Dy(PPP) 27−/mL suspension at low or high divalent cation concentration. The situation was improved at 5 μmol Dy(PPP)27−/mL suspension especially at high divalent cation concentration (2.5 mM). Incubation with Dy3+, PPP5−or Dy(TTHA)3−caused little or no structural effects but dysprosium was found to penetrate slowly inside tubules with Dy(TTHA)3−. Both Dy3+and Dy(PPP) 27−penetrated rapidly inside cells. Dysprosium was found to bind to the isolated cytosol but not to isolated membranes, eliminating the possibility of ext

ISSN:0952-3480    

DOI:10.1002/nbm.1940050103

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractTwo‐dimensional1H spectroscopic imaging and magnetic resonance imaging were used to study focal ischemia induced by middle cerebral artery occlusion in rats. A water suppressing spin‐echo sequence was used at 4.7 T. Phase encoding during the spin‐echo delay (TE = 272 ms) yielded an 8 × 8 array of 35 μL voxels. The injured area of the brain had a higher lactate level and markedly lowerN‐acetyl aspartate, creatine and choline levels than did the non‐ischemic regions. The spectroscopic imaging data clearly showed the localization of the infarct, which agreed well with both magnetic resonance imaging and the histological data obtained post‐mortem. This study demonstrates the potential usefulness of combining magnetic resonance imaging and1H spectroscopic imaging for studying animal models of stroke, and indicates the suitability of the technique for further pharmacologic

ISSN:0952-3480    

DOI:10.1002/nbm.1940050104

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractHearts from fed male Wistar rats (200–350 g) were perfused at low and high workloads with Pi‐free Krebs‐Henseleit medium containing either 10 mMglucose or 10 mMglucose plus 15mU/mL insulin. The intracellular pH by31P NMR ranged between 6.99 and 7.02 and agreed to within 0.1 pH unit of estimates calculated using enzymatically determined total tissue HCO3−/CO2contents. At high work, where the tissue contents of phosphocreatine (PCr) and ATP were determined on the same heart as NMR areas (n= 16), the proportionality factors, defined as the31P NMR area units divided by the total enzymatically determined tissue content (area units/μmol/g dry wt), were 112±8 for PCr, 99±4 for γ‐ATP, 138±9 for α‐ATP and 100±4 for β‐ATP. These values were normalized by taking β‐ATP as 100 area units/μmol/g dry wt. Since the proportionality factor for PCr and γ‐ and β‐ATP were not statistically different (p<0.05), it was concluded that each was equally visible by31P NMR and that no significant breakdown of PCr occurred during freezing or tissue acid extraction procedures. The cytosolic Piestimated from NMR in glucose plus insulin perfused hearts at low and high work was 4.92±0.67 and 6.33±0.42 μmol/g dry wt. Using the near‐equilibrium expression of KCK/KG+Gand the metabolite levels in heart extracts, the calculated cytosolic Piwas 13.08±1.83 and 16.17±3.08 μmol/g dry wt, respectively. The cytosolic NMR Piin the glucose hearts was 8.42±1.0 and 8.42±0.75 μmol/g dry wt at low and high work and 12.08±1.58 and 27.20±4.20±μmol/g dry wt from near‐equilibrium estimates. The total tissue Pimeasured enzymatically on freeze‐clamped hearts ranged from 18.0 to 26.42 μmol/g dry wt. The validity of using both the31P NMR and the near‐equilibrium method

ISSN:0952-3480    

DOI:10.1002/nbm.1940050105

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractWe had previously found (P. B. Garlick, T. R. Brown, R. H. Sullivan and K. Ugurbil,J. Mol. Cell Cardiol.15, 855–858 (1983)) that two peaks could be observed in the phosphate region of NMR spectra of isolated, perfused rat hearts. Upon valinomycin treatment, an increase in the peak at 2.8 ppm in the phosphate region (phosphocreatine set at −2.52 ppm) had been observed. We have now confirmed our hypothesis that this peak originates from the mitochondrial phosphate by: (i) determination of myocardial mitochondrial phosphate contents using density gradient centrifugation in non‐aqueous solvents; and (ii) quantitative electron microscopy of the heart tissue. Thus, we conclude that mitochondrial and cytosolic phosphate can be distinguished from each other in31P NMR spectra of isolated, perfused rat h

ISSN:0952-3480    

DOI:10.1002/nbm.1940050106

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe aims of this study were two‐fold: to characterize thein vivo31P NMR spectrum of human breast tumours by identifying the metabolites contributing to each peak; and to demonstrate changes in the detectability of the phosphodiester (PDE) peak at varying field strengths. This was achieved by obtaining31P spectra from 23 patientsin vivoat 1.5 T and also of 11 perchloric acid (PCA) extracts and 3 chloroform‐methanol (CM) extracts of tumour biopsy samples at 9.4 T. In spectra acquiredin vivothe percentage areas for each peak were: phosphomenoester (PME), 15%; Pi, 11%; PDE 35%; phosphocreatine, 5%; γ‐NTP, 11%; α‐NTP, 11% and β‐NTP, 12% of the total spectral area. PCA extracts showed the PME peak to be>70% phosphorylethanolamine whilst the PDE peak included almost equal proportions of glycerophosphorylethanolamine and glycerophosphorylcholine. CM extracts of tumours revealed additional metabolites in the PDE region suggesting that the large PDE peak observedin vivocould arise mainly from phospholipids. Spectra of human breast tumour xenografts examinedin vivoat both 1.9 T and 9.4 T confirmed that the presence of a large PDE peakin vivowas a function of field strength. Further experiments with microsomal membranes from rat mammary tumours at 1.5 and 9.4 T demonstrated that phospholipids are more clearly visible at the lower field strength due to a substantial decrease

ISSN:0952-3480    

DOI:10.1002/nbm.1940050107

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe1H NMR spectrum of the putative neurotransmitter dipeptideN‐acetylaspartylglutamate (NAAG) is described, along with its identification in acid extracts of tissues of the central and peripheral nervous systems of the rat. TheN‐acetyl methyl resonance of NAAG (2.058 ppm) is close to that ofN‐acetylaspartate (NAA, 2.022 ppm), a prominent signal in1H NMR spectra of the brain. The tissue concentration of NAAG is such that resonances of NAAG do not contribute greatly to1H NMR spectra of the brain, except in studies of the brain stem or thalamus. In the spinal cord and peripheral nerves the level of NAAG is similar to that of NAA, and NAAG is a major metabolite contributing to the1H NMR spectrum. The implications of these observations for1H NMR spectrain vivoare disc

ISSN:0952-3480    

DOI:10.1002/nbm.1940050108

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractWe have developed a reliable, reproducible model of hypoxia in the gerbil.1H and31P NMR spectroscopy demonstrates that cerebral energy metabolism is very resistant to hypoxia. Cerebral blood flow (measured by hydrogen clearance) began to increase when the arterial oxygen tension (paO2) was reduced to 40–50 mm Hg, and there was no change in phosphorus metabolites or lactate untilpaO2was below 40 mm Hg. In 50% of the animals lactate increased prior to any change in the phosphorus metabolites or intracellular pH, suggesting that1H NMR may be more sensitive than31P NMR at detecting hypoxic or ischaemic changes. The calculated rate of oxygen delivery at a time when phosphorus energy metabolism becomes impaired is similar in both hypoxia and ischaemia (ca 4 mL/100 g/min). We suggest that the critical factor in ischaemia is the reduction in oxygen supply, rather than the accumulation of toxic metabolites, such as lactat

ISSN:0952-3480    

DOI:10.1002/nbm.1940050109

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940050102

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY