ISSN:0952-3480    

DOI:10.1002/nbm.1940080102

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPhosphorus‐31 NMR spectra in rabbit liver were successively observed for more than 5 months in a chronic CCI4intoxication model using implanted wireless surface coils. The quality of the obtained NMR spectra was satisfactory and there was sufficient time resolution to follow the dynamic changes that occurred during a fructose tolerance test. The implanted coil did not lead to any serious adverse effects such as infection or liver dysfunction. During an 18‐week administration of CCI4, the area of the phosphodiester peak significantly decreased. The ratio of Pi/β‐ATP was transiently elevated and gradually returned to the control level. In the fructose tolerance test, the increase in phosphomonoester and the decrease in Piand β‐ATP after i.v. fructose loading were apparent, but the degrees in these changes became smaller during the CCI4intoxication. This wireless surface coil was useful for consecutive and non‐invasive31P NMR observations of the liver to follow chronically treated animal models over a period of sev

ISSN:0952-3480    

DOI:10.1002/nbm.1940080103

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis investigation was performed to determine (i) whether31P spatially localized31P NMR spectroscopy could be utilized to determine the transmural distribution of 2‐deoxyglucose (2DG) uptake in thein vivocanine heart and (ii) whether transmural 2DG uptake would be affected by a preceding ischemic insult. 2DG was infused and the accumulation of 2‐deoxyglucose‐6‐phosphate (2DGP) was monitored (by means of spatially localized31P NMR) in control hearts, in pharmacologically hyperperfused hearts, and in hearts subjected to four (5 min) occlusions of the left anterior descending coronary artery. Myocardial blood flow was measured with radioactive microspheres. In control hearts, subendocardial (ENDO) 2DGP contents were significantly higher than those in the subepicardium (EPI) being 3.8±0.3 and 2.2±0.2 m̈mol/g, respectively; the ENDO/EPI ratio of 2DGP was 1.70±0.21. During hyperperfusion blood flow increased approximately four‐fold but 2DGP accumulation was not altered. ATP levels in post‐ischemic myocardium were significantly decreased (ENDO more than EPI) and 2DGP accumulation in each layer was increased (p<0.01 vs control); however, the ENDO/EPI ratio of 2DGP was not altered. 2DG infusion induced a marked elevation of blood insulin and norepinephrine levels. These data demonstrate that in the presence of high blood levels of 2DG and insulin: (i) 2DGP accumulation can be measured in thein vivocanine heart; (ii) in normal hearts 2DG uptake is more pronounced in the inner layers of the left ventricular wall (this transmural 2DG uptake gradient is not due to subendocardial hypoperfusion); and (iii) 2DG uptake is greater in the post‐ischemic heart but the ENDO/EPI gradient of 2DG uptake is not altered indicating that the more severe ischemic insult in the subendocardium does not result in a disproportionate increase in 2DG uptake in that region of the myocardium. Although 2DG uptake patterns in this model most probably reflect those of glucose (at comparable glucose and insulin levels), quantitative extrapolations with regard to the rate of glucose uptake are not possible from

ISSN:0952-3480    

DOI:10.1002/nbm.1940080104

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractIdentification of a case of acute salicylate intoxication using 300 MHz1H NMR spectroscopy of a urine sample is reported. It has been achieved by using a combination of a one‐dimensional experiment with water presaturation and a two‐dimensional homonuclear J‐resolved experiment. By these means, lysine and the three major metabolites of acetylsalicylic acid have been assigned in the crude urine. The results are compared with those obtained at 600 MHz and with classical biochemical methods. The use of this method for routine diagnosis in biological analysis is disc

ISSN:0952-3480    

DOI:10.1002/nbm.1940080105

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe transverse relaxation rates R2and R*2were measured at 3 T in the substantia nigra of the midbrain of adult normal human controls. The relaxation rate arising from magnetic inhomogeneities, R2′, was calculated from the relationship R*2=R2+R2′. No significant differences were found for any parameters between left and right side substantia nigral regions, however, a significant inverse correlation was found between R2and R2′ (r=0.70, p=0.035). Water diffusion, in the presence of paramagnetic metal ions, may play a role in determining the relative contributions to reversible and irreversible transverse relaxation and may explain the inverse correlation demonstrated

ISSN:0952-3480    

DOI:10.1002/nbm.1940080106

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractLittle is known about the metabolic effects of ischaemia on high energy phosphatesin vivoin smooth muscle. We have developed a method for reversibly occluding the uterine artery, which allows simultaneous measurement of uterine metabolites using31P NMR spectroscopy, and intra‐uterine pressure,in vivoduring ischaemia. We have investigated the effects of repeated ischaemia on metabolites, intracellular pH and contractions in anaesthetized rats. Occlusion produced an immediate drop in uterine blood flow and decreased contractions. Although contractions recovered upon reperfusion after both occlusions, the contractile activity was less after the second period of occlusion, suggesting less resistance after a prior ischaemic period. Significant falls in [ATP] and [phosphocreatine]and an increase in [Pi] occurred during both occlusions. These were all reversed within 30 min of reperfusion. There was a large drop in intracellular pH produced by occlusion, which was rapidly reversed upon reperfusion. The changes in metabolites and intracellular pH were similar during the repeated ischaemic period, to those occurring during the first ischaemic period suggesting no alteration in energy production or utilization had occurred, with prior exposure to ischaemia. The significance of these results to the functioning of the uterus in labour is briefly discusse

ISSN:0952-3480    

DOI:10.1002/nbm.1940080107

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractMetabolic characteristics of colon mucosa, submucosa, muscularis and tumour specimens from four control (n = 105) and nine carcinogen (azoxymethane)‐treated (n = 91) Sprague‐Dawley rats were investigated byex vivo1H MRS. Ninety‐seven per cent of pure mucosa samples (n = 59) yielded spectra with narrow lipid resonances (chemical shift δ of ‐ (CH2)n‐, 1.3 ppm; linewidth at half‐height v1/2, 30‐50 Hz). Eighty‐two per cent of control mucosa samples with histologically proven submucosa contamination (n = 11) and 46% of control cross‐sections (containing mucosa, submucosa and muscularis; n = 57) yielded spectra with broad lipid resonances (δ ‐ (CH2)n‐, 1.5 ppm; v1/2, 80‐100 Hz) identical to those of adipose tissue surrounding rat colon. Thirty per cent of tumour samples (n = 10) yielded spectra with narrow lipid resonances while 70% contained no significant amount of MR visible lipids. We conclude that (i) lipids giving rise to broad resonances are in the heterogeneously distributed adipocytes of submucosa, (ii) lipids giving rise to narrow resonances are within the mucosa in an unknown structural environment, and (iii) the type and distribution of lipids in human and rat colon are similar. Tumours contained significantly more taurine than pure control mucosa (n = 15; p<0.004) and pure mucosa containing aberrant crypt foci (putative preneoplasm, n = 36; p<0.002). Our results suggest that the rat colon is a good model for1H MR investigations of h

ISSN:0952-3480    

DOI:10.1002/nbm.1940080108

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of hypoxia (inspired oxygen fraction, F1O2of 10% and 16%) and hyperoxia (F1O2) of 100%) on gradient echo images of the brain using long echo times was investigated in six healthy volunteers (age 24‐28 years). Different flip angles were used with an F1O2of 10% to assess the importance of saturation effects. The total cerebral blood flow was measured by a phase mapping technique during normoxia as well as hypoxia (F1O2of 10% and 16%) and hyperoxia (F1O2of 50% and 100%). High relative signal changes were found, independently of the flip angle, with F1O2of 10%. With a flip angle of 40° the values of δR2* for cortical grey matter, central grey matter, white matter and the sagittal sinus were 0.79, 0.41, 0.26 and 3.00/s; with a flip angle of 10° the corresponding values were 0.70, 0.37, 0.24 and 3.15/s. The total cerebral blood flow increased by 41% during inhalation of 10% O2and decreased by 27% during 100% O2; no flow changes were seen during moderate changes in F1O2. It is concluded that flow effects play a minor role for fMRI signal strength in this application since (i) they did not abolish the signal changes caused by changes in blood oxygenation during hyper‐ and hypoxia, (ii) the observed signal changes were closely related to the changes in arterial oxygen saturation during hypoxia and (iii) the signal changes were little affected by changing the flip angle from 40

ISSN:0952-3480    

DOI:10.1002/nbm.1940080109

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940080110

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940080101

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY