摘要:

AbstractDysprosium(III) triethylenetraamine‐N,N,N′,N″,N‴,N‴‐hexaacetic acid (DyTTHA3–) was used as an aqueous chemical shift reagent in conjunction with high‐resolution nuclear magnetic resonance (NMR) spectroscopy to monitor 87‐rubidium (87Rb+) transport in human erythrocyte suspensions. NMR spectra demonstrated two resonances which were assigned to the intra‐ and extracellular compartments of the erythrocyte suspension. Uptake of87Rb+was shown to proceed via the [Na,K]‐ATPase dependent pump as evidenced by the inhibition of uptake in the presence of ouabain. The steady state intra‐ to extracellular concentration ratio of87Rb was 3.00 and 1.13 in the absence and presence of ouabain, respectively. The rate of uptake of87Rb+in the absence and presence of ouabain was found to be 1.3 and 0.5 mmol Rb+/L erythrocytes/h at 18 mM Rb+, respectively. Data are also presented which indicate that the intracellular component of18Rb is les

ISSN:0952-3480    

DOI:10.1002/nbm.1940020202

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn vivodeuterium magnetic resonance spectroscopy was used to measure fat utilization rates in diabetic and non‐diabetic obese and non‐obese mice. Monosodium glutamate‐treated mice were used as a model for obesity, and diabetes was induced by administration of streptozotocin. Deuterium levels were enhanced by addition of D2O to drinking water (10% v/v) for a period of 14 days. The deuterium magnetic resonance signals of the body water and adipose tissue were then monitored to measure the rate of deuterium loss from the body. The rates of fat utilization for obese mice were significantly lower (75%,p<0.05) (halflife,t1/2= 113 ± 13 days) than the rates for non‐obese mice (t1/2= 30.0 ± 9.0 days). The induction of diabetes caused a large (90%) but proportionally similar increase in fat utilization for both groups of mice (obese,t1/2= 11.0 ± 5.2; non‐obese,t1/2= 3.0 ± 0.9). The results suggest that the induction of diabetes in obese mice does not affect the utilization of fat as a metabolic fuel. These preliminary studies indicate that deuterium magnetic resonance spectroscopy may be a useful technique for non‐invasive determination of the rates of fat uti

ISSN:0952-3480    

DOI:10.1002/nbm.1940020203

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractNormal and ‘Hahn’ spin‐echo 500 MHz1H NMR spectra of 21 pairs of plasma from mother and cord taken at the time of delivery are reported. The concentrations of ‘NMR‐visible’ lactate, alanine, and valine in the cord plasma significantly exceed those in the maternal plasma. In both maternal and cord plasma, measured lactate levels appear to increase with the length of the second stage of labour. Ethanol was unexpectedly detected in five samples of cord plasma. Lipoprotein —CH3and —(CH2)n— resonances are more intense in the spectra of maternal plasma compared to cord plasma, and are unusual in composition. The intensities ofN‐acetyl signals from ‘acute‐phase’ plasma glycoproteins are greater in spin‐echo spectra of maternal plasma compared to those of cord plasma (mean ratio 2.1 (SD 0.8)). These results suggest that high resolution NMR spectroscopy may provide a useful new insight into the comparative biochemistry

ISSN:0952-3480    

DOI:10.1002/nbm.1940020204

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe specificity of detecting cancer using the methyl and methylene linewidths in the1H NMR spectrum of plasma has been examined for patients with brain tumors. Apparently healthy controls are distinguished from patients with metastatic brain tumors or malignant primary intracranial neoplasms, although the amount of overlap with the latter group precludes the use of the method as a diagnostic tool. Furthermore, patients with benign primary intracranial neoplasms are not distinguished from those with malignant primary brain tumors, and non‐tumor neurological patients with traumatic head injury are not distinguished from cancer patients. Surgical treatment of neurological patients results in a significant narrowing of the1H NMR bands of interest, particularly for patients initially exhibiting broad lines. The narrowing persists for at least 3 weeks. This effect of surgical or other trauma on the1H NMR linewidths indicates that the method is unsuitable for assessing the efficacy of surgical treatment of cance

ISSN:0952-3480    

DOI:10.1002/nbm.1940020205

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

Abstract1H NMR studies of glycolysis in washed cell suspensions ofStreptococcus faecalisindicated that intracellular lactate is not1H NMR visible. Evidence for this was gained from time course studies of glycolysis at increasing concentrations of glucose. A close correlation existed between the relative increase in the lactate integral and the enzymatically determined extracellular lactate concentration [Lo]. When ionophores which cause the collapse of the positive intracellular/extracellular lactate gradient were added to cell suspensions following fermentation of 5, 10 and 50 mMglucose, the increase in the lactate integral was proportional to the respective increase in [Lo]. A more direct method for determining the origin of the lactate signal involved centrifugation of a cell suspension after fermentation of 50 mMglucose and measurement of lactate in the extracellular and intracellular fluid.1H spectra of the cell suspension, supernatant and sonicated pellet revealed that the lactate observed in the cell suspension was equivalent to the lactate in the supernatant alone. The intracellular lactate contained in the pellet represented 42% of the total lactate, indicating that only 58% of lactate is detected byin vivo1H MRS ofS. faecalis. This result is in contrast with the high percentage (70–90%) ofin vitrolactate which is detected byin vivo1H MRS of mammalian brain tissue (Williams S. R.et al. Magn. Res. Med.7, 425–431, 1988). This may be due to a higher proportion of extracellular lactate in mammalian tissue or differences in the intracellular environments of bacterial and mammalian ce

ISSN:0952-3480    

DOI:10.1002/nbm.1940020206

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe binding of histidine (His), phenylalanine (Phe) and tyrosine (Tyr) to macromolecules in blood plasma and serum has been investigated by high resolution1H NMR spectroscopy. In single pulse and spin‐echo spectra of quality control bovine serum and normal human plasma, there are no resonances in the chemical shift range to high frequency of δ = 5.3 ppm when measured in the pH*(meter reading, uncorrected for the presence of2H2O) range 3 to 8.5. On acidification of the plasma to pH*<2.5, resonances from His and Phe are observable. In plasma from patients with Wilson's disease, weak signals from His and Tyr are seen in spin‐echo spectra at pH*7.6, but increase in strength on acidification and signals from Phe appear at pH* 1.8. Addition of standard solutions containing Tyr, His and especially Phe and Trp to plasma at neutral pH* results in poor recovery of their expected signal intensity in spin‐echo spectra. Addition of 2Murea to bovine plasma at pH* 4.5 results in the appearance of Phe signals. These data are consistent with Phe and Tyr (and to a lesser extent His) being bound in or to a macromolecular structure at neutral pH from which there is relatively slow exchange with the free solution environment. Experiments with model solutions suggest that serum albumin has a high capacity for binding aromatic amino acids (stabilized by hydrophobic interactions) at neutral pH and this is responsible for the NMR‐invisibility of Tyr and Phe in bloo

ISSN:0952-3480    

DOI:10.1002/nbm.1940020207

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe chronological changes in the pattern of31P magnetic resonance spectroscopy (MRS) associated with cerebral infarction were studied in rats.31P MRS of chronic infarction (1 month after induction of infarction) clearly showed a pattern distinct from that of normal brain. In chronic infarction, the relative phosphomonoester (PME) level was found to be significantly higher and relative phosphocreatine (PCr) level significantly lower compared to normal brain. The intracellular pH and the relative inorganic phosphate (Pi) level did not show any significant differences. Histological examination indicated that the31P MRS pattern of chronic infarction reflects gliosis.

ISSN:0952-3480    

DOI:10.1002/nbm.1940020208

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940020210

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY