ISSN:0952-3480    

DOI:10.1002/nbm.1940080302

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940080303

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940080304

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractQuantitative proton spectroscopic studies were performed on 39 volunteers and 16 patients with intracranial tumours. Estimates of T2were obtained in white matter, grey matter, cerebellum, astrocytomas and meningiomas; T1was determined in white matter only. White matter values of T2for trimethylamines, creatine and N‐acetyl aspartate (NAA) were 309±84, 195±41 and 369±124ms, respectively (mean±SD, n = 20). Metabolite concentrations in white matter were 2.0±0.4 m̈mol/g wet weight for trimethylamines, 7.3±1.1 for creatine and 11.4±1.4 for NAA. The mean concentrations of creatine and NAA in grey matter and all of three metabolites in cerebellum were greater than those in white matter. Tumour spectra were characterized by increased trimethylamines, reduced creatine and NAA and occasionally the presence of lactate. Meningiomas were further characterized by the presence of alanine. The mean T2and concentration of trimethylamines in tumours was significantly greater than in normal brain. Creatine and NAA concentrations were decreased in all tumours. The longer T2of trimethylamines and presence of alanine in meningiomas indicate that important differences exist in membrane and glucose metabolism within these tumours when compared to either astrocytomas or normal bra

ISSN:0952-3480    

DOI:10.1002/nbm.1940080305

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPulsed field gradient (PFG) spin echo31P NMR can be used to measure diffusion coefficients of phosphorus‐containing metabolitesin vivo. In biological spin echo spectra, the ATP resonances are phase modulated by J‐coupling between the three phosphorus atoms. This phase modulation may severely decrease the apparent signal intensity of the ATP peaks. In this paper, we describe the use of homonuclear decoupling during spin evolution to suppress the effects of J‐coupling in biological spin echo spectra. Phosphorous spectra of ATP and creatine phosphate (PCr) in solution and goldfish(Carassius auratus)skeletal muscle demonstrate the effectiveness of homonuclear decoupling in improving the effective signal‐to‐noise ratio of ATP. In addition, diffusion coefficients of ATP and PCr determined in goldfish skeletal muscle show that PFG homonuclear decoupled spin echo (HDSE) NMR provides accurate measures of diffusion coe

ISSN:0952-3480    

DOI:10.1002/nbm.1940080306

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractImage directed localized1H NMR spectra were obtained at 7 T (300 MHz) from cubic volumes of less than 40 m̈L in the gerbil brain. Signals from cerebral metabolites commonly detected in other rodent species were easily assigned, and high resolution spectroscopy (360 MHz) of aqueous brain extracts assisted the tentative identification of partially overlapping resonances from lower concentration compounds like alanine, lysine, γ‐aminobutyrate, valine, leucine and isoleucine. Weak coupling at 7 T was manifest in the resolution of signals from the γ‐CH2groups of glutamine and glutamate. Down‐field of water, signals assigned to purine nucleotides were conspicuous in the extract spectra, but localized spectra acquired routinelyin vivo, using selective excitation and gradient crushing (SUBMERGE) for water suppression, exhibited little or no signal from purines. When localizedin vivospectra were acquired without water suppression, however, or using a low power binomial excitation sequence rather than SUBMERGE, a broad signal appeared at the resonant frequency of purine aromatic protons. NMR experiments on the nucleotide adenosine 5′‐monophosphate (AMP) in 90% glycerol/10% D2O solution demonstrated that pre‐irradiation of the water signal even for less than 100 ms attenuated the nucleotide signal appreciably. This implies that the soft pulses required for selective excitation of water in sequences such as SUBMERGE induce spin‐diffusion which eliminates or diminishes the signal from nu

ISSN:0952-3480    

DOI:10.1002/nbm.1940080307

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

Abstract31P NMR spectra were obtained from sera of 22 healthy volunteers and 20 patients with multiple myeloma at the time of diagnosis and repeated up to five times during therapy. All spectra consisted of a Pipeak (used as a reference peak) and two peaks from phospholipids (PL): one peak due to phosphatidylethanolamine and sphingomyelin (PE + SM) and a second peak due to phosphatidylcholine (PC). Prior to therapy, peak intensities of the phospholipids were low relative to Pi. During therapy leading to remission, the resonance from PL progressively increased to approximate the spectral pattern seen in normal sera. By contrast, in non‐responders an opposite trend was noted: the intensities of the phospholipid peaks became progressively reduced or remained unchanged. Long‐term follow‐up studies showed a good correlation between this31P MRS evaluation of sera and the response of the disease to the therapy. In addition to the correlation with tumor response, our studies also show significant correlations between area, intensities of peaks of PE + SM, PC, and the concentrations of high‐density lipoprotein (HDL) (correlation coefficients 0.46, 0.43, 0.59, respectively; p<0.001). We found that the concentration of HDL in serum of patients with multiple myeloma was significantly reduced. In individuals responding to therapy HDL levels increased to the point where there were no statistically significant differences between them and healthy volunteers. In patients not responding to therapy, HDL concentration did not increase. In summary, analysis of plasma lipids by MRS offers a convenient method for establishing a blood lipid profile in patients with haematological malignant disease and offers yet another modality for assessing patient response to therapy in multiple

ISSN:0952-3480    

DOI:10.1002/nbm.1940080308

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe report13C NMR measurements of the flux through aldose reductase in isolated rat sciatic nerve, and its inhibition by an aldose reductase inhibitor of the sulphonylnitromethane class. [1‐13C] galactose was used as substrate, and the rate of production of [1‐13C] dulcitol was measured. Quantitation required the use both of internal extracellular, and external, standards. The mean net forward flux (±S.D) was 20±11 nmol/(mL nerve water)/min (n = 10). In the presence of the inhibitor, flux was reduced significantly (p<0.001) to 13% of control. Since dulcitol is symmetrical, an estimate of the backward flux, to [6‐13C] galactose, is also possible; under our conditions, this was neg

ISSN:0952-3480    

DOI:10.1002/nbm.1940080309

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940080301

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY