摘要:

AbstractThe mechanism behind the relative increase in high‐energy phosphates observed by MRS in many tumors following chemotherapy is poorly understood. To test the hypothesis that this metabolic activation is associated with a decrease in tumor hypoxia, tumor blood flow and oxygenation were measured in tumors that were also analyzed by MRS.31P MR spectra were acquired with a GE 2T CSI spectrometer from subcutaneous 9L tumors in rats 4 days following treatment with BCNU (10 mg/kg) and from age‐matched sham‐treated control tumors. BCNU‐treated tumors (n= 13) underwent a significant improvement in bioenergetic state compared to control tumors (n= 14), showing a relative increase in high‐energy phosphate (Pi/phosphocreatine) (p<0.01), and a relative decrease in Pi(Pi/anucleoside biphosphate) (p<0.01). Gamma camera imaging of133Xe washout, following injection of133Xe in saline into control and treated 9L tumors 4 days after treatment, was used to measure tumor perfusion. Sham‐treated control tumors (n= 21) were perfused at a rate of 35.4 (±6.4 SE) mL/100g/min, while BCNU‐treated tumors (n= 20) were perfused at a rate of 55.1 (±7.5 SE) mL/100g/min (T= 1.96;p<0.05). The partial pressure of oxygen (pO2), measured with a polarographic electrode was found to be significantly higher in treated 9L than in sham‐treated controls. Mean tumorpO2of sham‐treated tumors was 18.1 (±1.7 SE) mmHg (n= 00 measurements in six tumors) while meanpO2of treated tumors was 45.1 (±2.1 SE) mmHg (n= 500 in five tumors) (T= 10.12;p<0.001). If the range 0‐5 mmHg is taken to approximate the hypoxic fraction, then control tumors are ±23% hypoxic, while treated tumors are only 2% hypoxic. These data suggest that metabolic activation of tumors following therapy may be associated with decreased

ISSN:0952-3480    

DOI:10.1002/nbm.1940040302

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractHuman astrocytoma cells were cultured and inoculated into the rat brain. From the pre‐clinical to the terminal state, tumour growth was monitored byin vivoMR imaging and by localized water‐suppressed1H spectroscopy (0.12‐0.15 cm3volumes) and spectroscopic imaging (0.01 cm3voxels) employing the ACE localization technique. The MR experiments were conducted completely non‐invasively, leaving the scalp intact. Brain spectra were obtained, showing distinct resonances for more than five different brain metabolites; they were not contaminated with lipid signals because of the adequate localization. Tumour progression, monitored in a selected volume of interest, was reflected in the corresponding spectra by decreasing intensities for resonances ofN‐acetyl aspartate and (phospho)creatine and increasing intensities for resonances of choline compounds and lactate. From spectroscopic imaging experiments metabolic heterogeneity could be deduced within the tumorous region. At particular times during tumour development spectra were obtained greatly resembling localized1H MR spectra obtained from patients with astrocytomas by the use of similar localization methods. This emphasizes the relevance of animal model study for the evaluation of MR spectroscopic investigations in human brain tumour diagnosis and therapy e

ISSN:0952-3480    

DOI:10.1002/nbm.1940040303

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPhosphatidylcholine (PC) metabolism in bovine adrenal chromaffin cells has been studiedin vivowith 100 MHz13C NMR spectroscopy. The incorporation of13[CH3]choline was examined in cells embedded in 1% agarose strands and perfused at 37 °C. The pattern of13C NMR spectroscopy. The incorporation of [13CH3]choline incorporation into PC of suspension cultures of chromaffin cells. The chemical shifts of labelled carbons in [13CH3]choline before and after their incorporation into PC are identical (ca 56.4 ppm). Incorporated [13CH3]choline can be released from the cells by phospholipase D which reduces the cellular PC signal by>85%, indicating that a major fraction of the labelled PC is on the external membrane surface. This application of NMR spectroscopy provides a basis for direct measurement of thein vivometabolism of PC in functioning adrenal chromaffin cell

ISSN:0952-3480    

DOI:10.1002/nbm.1940040304

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPrevious studies have reported significant radiobiological and hemodynamic effects associated with sodium pentobarbital (PB) anesthetization. The present work contrasts the effects of PB with azaperone‐ketamine (AZ) in RIF‐1 and KHT tumors while animal body core temperature is maintained at 37 °C. The primary aims were to evaluate both agents in terms of: (i) duration of anesthetic; (ii) effect on absolute levels of31P NMR phosphocreatine (PCr) + β‐nucleoside triphosphate (β‐NTP)/inorganic phosphate (Pi) ratios; and (iii) effect on temporal variability of PCr+β‐NTP/Piratios. In terms of overall duration, AZ was the clear preference. Although the maintenance of 37 °C core temperature significantly reduced overall durations for both anesthetics, AZ animals invariably remained immobile for a minimum of 80 min. For PB, durations were highly unpredictable. With AZ, mean PCr + β‐NTP/Piratios were constant over the entire 80 min period for both lines. With PB, PCr + β‐NTP/Piratios were lower in relation to AZ for KHT at select timepoints, but highly variable among RIF‐1 tumours. Since ratios under PB varied substantially with time for RIF‐1 lines, measurements taken with PB are clearly not representative of the control state. Furthermore, in light of the consistent and reproducible results obtained with AZ, this anesthetic is considered a marked improvement over PB for anima

ISSN:0952-3480    

DOI:10.1002/nbm.1940040305

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe composite methylene (chemical shift range 1.2‐1.4 ppm) and methyl (0.8‐0.9 ppm) resonances of the1H NMR spectrum were analyzed in plasma samples from breast tumor patients, pregnant women, and healthy subjects. Using a 500 MHz NMR instrument operating at 25 °C, the peaks were analyzed for line width at half height and then averaged. A statistically significant difference (p<0.001) was found between the average (mean ±SD) line width in the plasma samples from the 30 patients with metastatic breast cancer (34.1 ±5.0 Hz) and the controls matched for age and sex (38.7 ±4.4 Hz). In the 16 patients with localized breast cancer and the 16 with regional spread, the average line width was not different from that of matched controls. In 21 patients with benign tumor in the breast, the average line width was not different from that of matched controls. A difference in the average line width was found between 31 pregnant women in the third trimester (32.5±3.4 Hz) and their controls matched for age and sex (42.7±4.6 Hz) (p<0.001). The average line width was lower in the late (31.5±3.3) than in the early (34.5±2.5 Hz) part of the third trimester (p= 0.022). In 54 healthy male and 130 healthy female controls, line widths declined gradually with increasing age by decades, except in the fifth decade for the men and the sixth decade for the women. The observations are consistent with an association between ‘stage’ in a most general sense and the apparent NMR lipid line widths, probably accounted for by a variation i

ISSN:0952-3480    

DOI:10.1002/nbm.1940040306

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractFully localized proton NMR spectra were obtained from the brains of normal anaesthetized ratsin vivousing stimulated echo (STEAM) spectroscopy sequences. Investigations were carried out at 2.35 T using a 40 cm bore magnet equipped with an actively shielded gradient system. Localized shimming resulted in water proton linewidths of 6.5‐7.8 Hz permitting excellent water suppression. Thus, high‐quality proton NMR spectra (TE= 20 ms) were acquired within measuring times of 1.5‐6.4 min from 64 to 125 μL volumes‐of‐interest. The spectra show metabolite resonances due toNaspartate, glutamate, creatine and phosphocreatine, cholines, taurine and inositols. The assignments of strongly spin‐coupled resonances were confirmed by comparison with spectra from model solutions obtained under identical experimental conditions to those used in vivo. Tl relaxation times as well as relative metabolite concentrations were evaluated from spectra obtained for repetition times ranging from 900 to 6000 ms. Sequential acquisitions of 1.5 min spectra before, during and after killing the animals exhibited a rapid accumulation of lactate, but did not reveal significant changes in other metabolite levels for several hours

ISSN:0952-3480    

DOI:10.1002/nbm.1940040307

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940040308

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940040301

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY