摘要:

AbstractThe steady‐state distribution of the general anesthetic halothane in different rat tissues, including a renal adenocarcinoma with and without hyperthermia treatment, has been evaluated byIn vivo19F NMR spectroscopy. The19F spectra of halothane (which is a hydrophobic probe) from within tissue show differences in the partitioning between normal rat tissues and adenocarcinoma. Muscle, as a control tissue, exhibits a single large resonance around 0 ppm. However, the adenocarcinoma exhibits two slow‐exchanging resonances separated by 0.3 ppm with the one at the more hydrophobic chemical shift being more sensitive to hyperthermia treatment. The results from this tumor model suggest that19F NMR spectroscopy may be useful first in detecting a change in hydrophobic environments using a lipophilic probe such as halothane, and secondly in monitoring the effects of hyperthermia, a treatment whose effectiveness may involve changes at the level of the plasma membrane. Under conditions of continuous delivery, a resonance which is not detected in the spectra of halothane in excised tissue appears 5 ppm downfield from the resonance for halothane localized in tissues. A rotating frame experiment is used to show that this resonance is derived from anesthetic absorbed on the tissue surf

ISSN:0952-3480    

DOI:10.1002/nbm.1940060502

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractGrowth and magnetic resonance characteristics of a human squamous cell carcinoma SQ20B were studiedin vivoas xenografts in nu/nu nude mice. Tumor cells injected subcutaneously in the flank using either MatrigelTM(MTG, an extract of basement membrane proteins) or growth medium (GM) as a vehicle were compared. Much higher tumor growth rates and cell density were observed with MatrigelTMthan with GM implantation. Histology also showed that MTG implanted cells grew as vascularized solid tumors compared to GM tumors which formed cysts. As a result of increased cell density with the improved method, tumors as small as 0.3 cm3provide high S/N magnetic resonance spectra which yield smaller standard deviations with fewer experiments.

ISSN:0952-3480    

DOI:10.1002/nbm.1940060503

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractWe use the hyperbolic relationship between cytosolic [ADP] and the rate of phosphocreatine (PCr) resynthesis after exercise to estimate the apparent maximum rate of oxidative ATP synthesis (QMAX). We examine data from some human diseases in which mitochondrial oxidation may be impaired (due to reduced mitochondrial numbers, intrinsic mitochondrial defect or impaired vascular supply). Muscle responds to impaired oxidation by stimulating anaerobic ATP synthesis and/or by increasing [ADP], the stimulus to the mitochondrion. However, these responses interact: [ADP]depends on pH and [PCr], and lactic acid production tends to lower [ADP](by lowering pH), while proton efflux has the opposite effect. We identify four patterns of results: (A) in mitochondrial myopathy, apparentQMAXis reduced and [ADP] is appropriately increased, because increased proton efflux reduces the pH change in exercise despite increased lactic acid production; (B) in some conditions (e.g., cyanotic congenital heart disease) apparentQMAXis reduced but there is no compensatory rise in [ADP], probably because anaerobic ATP synthesis during exercise is increased without increase in proton efflux; (C) in other conditions (e.g., myotonic dystrophy) [ADP]is increased during exercise but apparentQMAXis normal, suggesting either an increase in proton efflux and/or decrease in anaerobic ATP synthesis during exercise; (D) there are also conditions (e.g., respiratory failure) where, despite impaired oxygen supply, both apparentQMAXand end‐exercise [ADP] are normal. We also discuss the metabolic conditions under which end‐exercise [ADP]is increased by a mitochondrial defect. Finally, we discuss some technical aspects, including the effects of an altered mitochondrialKmfor ADP and the relationship of the analysis to the halftime of PCr recovery and an alternative calculation of apparentQ

ISSN:0952-3480    

DOI:10.1002/nbm.1940060504

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe goal of this study was to examine metabolic differences between cortex and basal ganglia in normal rat brain and to determine postmortem changes usingin vivo1H magnetic resonance spectroscopic imaging at 300 MHz. The resonances observed were: choline, creatine+phosphocreatine,N‐acetyl aspartate (NAA), lactate (Lac), and three small resonances in the amino acid region which included resonances from aspartate + NAA (Asp), glutamine + NAA (Gln), and glutamate+GABA (Glu). A previously unassigned resonance was observed at 1.13 ppm in brain of rats anesthetized with pentobarbital. Spectroscopic images in normal brain demonstrated increased NAA and Gln and decreased Glu in cortex compared to basal ganglia. The major postmortem changes were an increase of Lac, Glu and Cho and a decrease of NAA and Asp. The rise in Lac was significantly higher in cortex than in basal gangli

ISSN:0952-3480    

DOI:10.1002/nbm.1940060505

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe content of the phospholipid metabolites, phosphocholine, phosphoethanolamine, glycerophosphorylcholine and glycerophosphorylethanolamine was measured in chemical extracts from 46 human breast carcinoma using31P NMR spectroscopy. Some patients had received therapy prior to tumour resection. The data were therefore stratified into two groups: (i) all tumours; and (ii) untreated tumours. Three indices of tumour proliferation i.e., mitotic index, Ki67 and S‐phase fraction were determined on tissue from the same tumours and were found not to correlate with the content of any of these metabolites. In addition oestrogen‐receptor status and density, tumour grade and DNA ploidy were obtained on some tumours. The phosphocholine content was higher in high grade tumours when compared with low grade tumours. There was no apparent relationship between DNA ploidy and the content of any of these metabolites. Glycerophosphorylcholine content of oestrogen‐receptor positive tumours correlated with receptor density. However, there was no significant difference between receptor positive and negative tumours in the content of any of the phospholipid metabolites mea

ISSN:0952-3480    

DOI:10.1002/nbm.1940060506

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn vivo, volume‐selected1H NMR spectroscopy employing the SPACE technique was used to monitor biochemical changes in the thiamin deficient rat brain in response to glucose loading. The concentrations of brainN‐acetylaspartate, glutamate/glutamine/γ‐aminobutyric acid, lactate and glucose differed significantly from those of control animals. The results are consistent with a metabolic block at the reaction catalyzed by the thiamin dependent enzyme α‐keto glutarate dehydrogenase soon after the onset of neurological symptoms of thiamin deficiency, and a further block at pyruvate dehydrogenase arising late in the course of thiamin d

ISSN:0952-3480    

DOI:10.1002/nbm.1940060507

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractTheT1andT2of kidneys in 5 normal volunteers and 27 patients with renal tumors were evaluated preoperatively using a magnetic resonance imager with a 0.1 T resistive electromagnet, and theT1andT2of the renal tumors were compared with the pathological findings: (i) theT1andT2of the normal renal medulla were longer than those of the normal renal cortex and psoas muscle; (ii) bothT1andT2of renal pelvic cancer (RPC) were shorter than those of renal cell cancer (RCC, p<0.05); (iii) theT2values of RPC were significantly shorter than those of renal medulla (P<0.01); (iv) theT1andT2of the normal renal cortex of subjects<50 years old were shorter than those of subjects ⩾50 years old (p<0.05 and p<0.01, respectively). These findings suggest that preoperative evaluation of the pathological findings of renal tumors may be possible by calculating the relaxation time using MRI under low magnetic fiel

ISSN:0952-3480    

DOI:10.1002/nbm.1940060508

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractPrevious studies suggested that hypoxia reduces the severity of brain injury after epileptic seizures. To test this hypothesis, the effect of hypoxic arrest of epileptic seizures on brain metabolism was investigated in rats by combiningin vivoNMR spectroscopy with imaging techniques for the pictorial evaluation of energy metabolism and pH. Seizures were produced by i.v. injection of bicuculline, and measurements were compared in animals with and without 5 min exposure to 5% oxygen after the onset of seizures. Transient hypoxia persistently reduced seizure activity, even after return to normoxia. Hypoxia or seizure alone had little effect on brain metabolism but the combination of both led to marked albeit reversible deterioration of energy and acid/base status. In normoxic animals pictorial measurements of energy state 2 h after the onset of seizures revealed a regional decline of ATP in the hippocampus. In animals in which seizures were arrested by transient hypoxia ATP depletion was additionally observed in the border zones of vascular territories. These results demonstrate that hypoxic arrest of seizure activity leads to the aggravation of metabolic disturbances and is therefore not suited to preventing permanent brain injury.

ISSN:0952-3480    

DOI:10.1002/nbm.1940060509

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractA sensitive radiotracer technique was used to measure transfer constants (Kis) for blood to brain diffusion of the MR contrast reagent gadolinium diethylenetriaminepentaacetate (GdDTPA2−) and the MR shift reagent dysprosium triethylenetetraminehexaacetate (DyTTHA3−) across the normal and the ischemically injured blood‐brain barrier (BBB) of rats. In rats with a normal BBB mean Kis (nL/g/s) for these reagents ranged from 0.3 to 1.4 across eight brain regions and were significantly lower in each region than Kis for sucrose (1.5–3.2), a substance known to be a poor permeant of the intact BBB. Kis measured 6h after a 10min period of normothermic forebrain ischemia were increased to 4.0–6.2 (reagents) and 6.6–7.5 (sucrose) in two brain regions, striatum and hippocampus, known to be especially vulnerable to ischemic injury. Measurements of BBB permeability to DyTTHA3−after osmotic opening of the barrier with hypertonic arabinose gave Kis of 25–30 in forebrain regions. Estimates of reagent concentrations in brain interstitial fluid 30 min after dosing the animals indicated that both an extremely high dose of DyTTHA3−and severe disruption of the BBB would be required to shift the resonance frequency of extracellular Na+appreciably. With the moderate degrees of BBB injury produced by short‐term ischemia, a dose of GdDTPA2−about 25 times the usual clinical dose of 0.1 mmol/kg would be required to quantify the

ISSN:0952-3480    

DOI:10.1002/nbm.1940060510

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940060501

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY