摘要:

AbstractMice with subcutaneous RIF‐1 tumors were anesthetized with sodium pentobarbital (PB) or ketamine plus acepromazine (KA) before acquisition ofin vivo31P nuclear magnetic resonance (NMR) spectra from tumors. The area of the inorganic phosphate resonance was significantly greater (relative to phosphomonoesters or the α‐phosphate resonance of nucleoside triphosphate) in spectra obtained under PB anesthesia, suggesting that the hypoxic fraction of the tumor increased following PB anesthesia.In vivonear‐infrared laser spectroscopy directly demonstrated that tumor oxyhemoglobin was reduced by more than 20% following PB but was not significantly affected by KA. Total hemoglobin (tumor blood volume) was reduced by 11% following PB anesthesia, but was not significantly affected by KA. Tumor growth delay induced by γ‐irradiation was shorter when tumors were irradiated under PB anesthesia than when irradiated under KA, showing that PB anesthesia had a radioprotective effect. These studies demonstrate that both the31P NMR and near infrared methods can detect metabolic or physiological changes associated with an increase in tumor radioresistance (i.e., an increase in the radiobiological hypoxic

ISSN:0952-3480    

DOI:10.1002/nbm.1940020302

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

Abstract31P NMR was used to study the erythrocytes of three patients who exhibited a familial multisystem disease characterized by fatty liver, diabetes and nonspherocytic hemolytic anemia of unknown etiology.31P NMR measurements disclosed an abnormally high level of intracellular inorganic phosphate (Pi) and an abnormally low level of ATP in the erythrocytes 6 h after blood withdrawal from proband (I–1). This finding suggested that ATP was markedly decreased in the red cells of this proband, as compared with those of normal subjects. Time‐dependent changes of31P NMR spectra of the erythrocytes from the two daughters (II‐1, II‐2) of the proband demonstrated clearly an enhanced decomposition of ATP with a concomitant increment of Pi. Several ATP‐consuming enzymes in erythrocytes, such as those in the Embden‐Meyerhof system, pentose phosphate pathway enzymes, Na+, K+‐ATPase and Ca2+, Mg2+‐ATPase, were within normal limits of activity, but Mg2+‐ATPase was drastically above the normal limit. The Mg2+‐ATPase activity was 3 times higher in the red cell membranes of these patients than in those f

ISSN:0952-3480    

DOI:10.1002/nbm.1940020303

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe build‐up and clearance of halothane in rat brain have been measured non‐invasively by19F NMR spectroscopy using a surface coil placed on the intact scalp. When the halothane supply (3% in O2/N2O, 33/66%) was turned off, the19F signal decreased exponentially to approximately 50% of the initial value, with a time constant, in normal rats, of 8.6 ± 0.7 min (mean ± SEM,n= 16), followed by a decay slower by at least one order of magnitude. The time constant of the rapid decay (r), which was found to be specific for brain, was reduced in hypoxic/hypercapnic (5% O2/5% CO2) rats to 2.9 ± 0.2 min (p= 0.001,n= 4), in rats infused with physostigmine (20 m̈/kg/min i.v.) to 5.7 ± 0.3 min (p= 0.005,n= 6) and increased in rats injected with pentothal (40 mg/kg i.p.) to 10.7 ± 1.6 min (p= 0.2,n= 5). Based on the theory of exchange of inert gas at the lungs and tissues developed by Kety, the rapid exponential decay of the19F signal was used to calculate relative cerebral blood flow (CBF). Assuming the cortical CBF in a normal rat to be about 130 mL min–1100 g–1, the following CBF values (means ± SEM) were obtained: controls 130 ± 10, hypoxia/hypercapnia 390 ± 59, hypercapnia 220 ± 25, physostigmine 195 ± 26, pentothal 105 ± 23 mL min–1100 g–1. These values are in good agreement with published values obtained with established methods. The rate of halothane elimination in the lungs does not significantly influence the relative CBF values, since hypercapnia (pCO2= 77–87) had the same effect on r in both mechanically ventilated and spontaneously breathing rats. It can be concluded that it is possible, using19F NMR spectroscopy, to determine relative tissue perfusion rates accurately and non‐invasively, averaged over time and volume, in live animals by measuring the exponential disappearance of a19F labelled i

ISSN:0952-3480    

DOI:10.1002/nbm.1940020304

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe metabolism of [1‐13C]glucose in the rat brain during hypoxia was investigated by13C NMR spectroscopy. Male Wistar rats, weighing 100–120 g, were anesthetized with ketamine (50 ˜ 75 mg/kg i.p.) and ventilated mechanically with a mixture of 30% oxygen, 69.5% nitrogen and 0.5% halothane. [1‐13C]glucose (250 mg/kg) was infused twice, at 10 minute intervals, through the femoral vein. For the control group (n= 4), the oxygen concentration of the inspiratory gas was maintained at 30% by vol throughout the experiments. For the hypoxia group (n= 6), the oxygen concentration in the inspiratory gas was reduced to 6–7% (93–94% nitrogen) and maintained for 30 min following [1‐13C]glucose infusion.13C NMR spectra were measured by a gated proton‐decoupling method without a nuclear Overhauser effect. The [1‐13C]glucose infusion gave apparent signals of the C1 carbon in the α‐ and β‐anomers of [1‐13C]glucose at 92.7 and 96.7 ppm, respectively. Signals of the C2, C3 and C4 carbon atoms in glutamate and/or glutamine (glx) also appeared at 55, 27 and 34 ppm, respectively. The intensity of glx‐C2 and glx‐C3 signals increased later than that of glx‐C4. The time lag between the different glx signals may reflect the turnover rate of the TCA cycle. Under the hypoxic condition, the signal of C3 carbon in lactate appeared at 21 ppm and increased. The α‐glucose signal diminished during hypoxia, whereas the β‐glucose signal kept its intensity. The difference in changes of the signal intensity between α‐ and β‐glucose suggests that α‐glucose is cons

ISSN:0952-3480    

DOI:10.1002/nbm.1940020305

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe broad phosphorus resonance of isolated perfused liver can be removed by selective presaturation with a DANTE pulse train. The use of the DANTE pulse allows the broad resonance to be removed without the use of multiple RF channels or the ability to switch the observation channel from low to high power.

ISSN:0952-3480    

DOI:10.1002/nbm.1940020306

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe metabolic response of the rat liver to flushing and reflushing with Marshall's solution at pH 7.2 or pH 7.8 has been studied by31P nuclear magnetic resonance spectroscopy. The changes in intracellular pH, inorganic phosphate, ATP and phosphomonoesters have been determined from the31P spectra. We show that the intracellular pH at any stage of the flushing protocol is largely independent of the pH of the medium when using these solutions. However, we demonstrate that there are differences between the efficiency of the two solutions in respect of the rates of hydrolysis of ATP and accumulation of phosphomonoesters. There were also differences in the response of the livers upon reflushing—those livers reflushed at pH 7.2 resynthesized ATP from a lower initial concentration to achieve ATP concentrations similar to those restored in livers reflushed at pH 7.8. These trends were mirrored in the responses of the phosphomonoester peaks (which contain a contribution from AMP). We conclude that short‐term control of liver metabolism during hypothermia is possible by use of solutions of different pH, but that for longer‐term storage, other approaches may be necessary to maintain metabolic inte

ISSN:0952-3480    

DOI:10.1002/nbm.1940020307

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractProgress in the development of non‐proton NMR applications in medical research has been hampered by the generally low sensitivity of these nuclides as well as the lack of instrumentation readily available for studying these spins. For example, custom head coils suitable for sodium imaging of the human head are either not available or very expensive, making research startup costs high or impossible. Herein the detailed design and construction of a research23Na head coil for MRI imaging is presented.23Na NMR images collected with the coil are presented as well as a discussion of design modifications for other nuclide

ISSN:0952-3480    

DOI:10.1002/nbm.1940020308

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe feasibility of broadband proton decoupledin vivo13C NMR spectroscopy of humans at 1.5 T was explored. A dual surface coil set‐up was used, comprising a circular13C coil and a butterfly1H decoupling coil placed at one third of its width away from the body. A calibration procedure was introduced to evaluate the specific absorption rate (SAR) in any gram of tissue for the inhomogeneous decoupling field generated by a surface coil. For the WALTZ‐4 sequence it was demonstrated that broadband decoupled spectra of both subcutaneous adipose and underlying muscle or liver tissue could be obtained at 1.5 T without exceeding recommended maximum SAR values. Broadband decoupling caused an additional resolution enhancement ascribed to the removal of (1H–13C) long range couplings. Broadband proton decoupled spectra of subcutaneous adipose tissue were obtained in less than 10 min showing highly resolved and intense signals of fully relaxed carbon spin systems of triacylglycerols. Broadband proton decoupled13C NMR spectra of calf muscle showed several resonances for metabolites resolved from triacylglycerol signals (e.g. C1–C5of glycogen, C4of histidine, aromatic and carbonyl carbons of aminoacids and N linked carbons of ethanolamine, choline and creatine). With an acquisition time of 20–30 min, the C1glycogen signal was observed with a root mean square signal‐to‐noise ratio of about 15. Not only the glycogen C1signal but also its C2–C6signals could be monitored in dynamic studies. Finally broadband proton decoupled13C spectra were obtained with signals from liver tissue (notably the carbons of glycogen). The localization of liver tissue from surrounding muscle tissue could be verified on the basis of the intensities of resonances typical of muscle tissue compounds. The signal strength of the liver glycogen C1signal was 2 to 3 times that of the glycogen C1signal of muscle after the same

ISSN:0952-3480    

DOI:10.1002/nbm.1940020309

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940020301

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY