bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐Invasive determination of cerebral blood flow changes by 19f NMR spectroscopy
Authors: Rudin Markus , Sauter Andre
Published: March 2007

The build‐up and clearance of halothane in rat brain have been measured non‐invasively by 19F NMR spectroscopy using a surface coil placed on the intact scalp. When the halothane supply (3% in O2/N2O, 33/66%) was turned off, the 19F 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 the 19F signal was used to calculate relative cerebral blood flow (CBF). Assuming the cortical CBF in a normal rat to be about 130 mL min–1 100 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–1 100 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, using 19F 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 a 19F labelled inert gas, such as halothane.
NMR study on [1‐13C]glucose metabolism in the rat brain during hypoxia
Authors: Fujiwara Naoshi , Shimoji Koki , Yuasa Tatsuhiko , Igarashi Hironaka , Miyatake Tadashi
Published: March 2007

The metabolism of [1‐13C]glucose in the rat brain during hypoxia was investigated by 13C 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 consumed more than β‐glucose in the hypoxic brain.
Broad resonance‐edited 31P spectra obtained with a single radiofrequency channel
Authors: Thoma William J. , Snyder John A. , Pearson Gerald A.
Published: March 2007

The 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.
Biochemical consequences of reflushing hypothermically‐stored liver with fresh cold perfusate. studies on rat liver using 31p NMR spectroscopy
Authors: Busza A. L. , Proctor E. , Fuller B. J.
Published: March 2007

The 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 by 31P nuclear magnetic resonance spectroscopy. The changes in intracellular pH, inorganic phosphate, ATP and phosphomonoesters have been determined from the 31P 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 integrity.
Linear drive birdcage coil for 23Na human head studies at 1.5 T
Authors: Lim Kelvin O. , Wolff Steven , Balaban Robert S.
Published: March 2007

Progress 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 research 23Na 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 nuclides.
Broadband proton decoupled natural abundance 13C NMR spectroscopy of humans at 1.5 T
Authors: Heerschap A. , Luyten P. R. , Van Der Heyden J. I. , Oosterwaal L. J. M. P. , Hollander J. A. Den
Published: March 2007

The feasibility of broadband proton decoupled in vivo 13C NMR spectroscopy of humans at 1.5 T was explored. A dual surface coil set‐up was used, comprising a circular 13C coil and a butterfly 1H 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 decoupled 13C NMR spectra of calf muscle showed several resonances for metabolites resolved from triacylglycerol signals (e.g. C1–C5 of glycogen, C4 of 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 C1 glycogen signal was observed with a root mean square signal‐to‐noise ratio of about 15. Not only the glycogen C1 signal but also its C2–C6 signals could be monitored in dynamic studies. Finally broadband proton decoupled 13C 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 C1 signal was 2 to 3 times that of the glycogen C1 signal of muscle after the same number of scans.
1H magnetic resonance of human tumours. Analysis of the transverse relaxation of the methylene protons using continuous distributions of relaxation times
Authors: Remin Mieczyslaw , Somorjai Rajmund L. , Deslauriers Roxanne , Princz Eva J. , Smith Ian C. P.
Published: March 2007

In tumours, the decay of 1H transverse magnetization (relaxation profile) of the methylene resonances is usually not a single exponential. The conventional sum‐of‐exponentials approximation often leads to several solutions which fit the experimental data; choosing one solution over another is highly subjective. We have therefore analyzed transverse relaxation data for the methylene resonance of lipids in human tumours, assuming a continuous distribution of relaxation times. We have studied 89 colon tumours (27 with metastasis), 12 ‘normal’ colon tissues, 40 breast tumours (24 with metastasis) and 13 malignant lymph nodes. All were primary tumours and the patients had received no previous treatment. Two continuous distribution approximations were tested. The two‐parameter lognormal distribution provides a simple representation of the relaxation profile. The constrained regularization method (Contin) complements and extends the lognormal approach. The average T2 values, 〈T2〉, whether derived from the lognormal or the Contin approximations, are consistent and comparable. Tumour and ‘normal’ colon tissue taken from the same patient show important differences in relaxation behaviour. A considerable broadening of the lognormal distribution, with 〈T2〉 shifted to shorter values, is observed for the colon tumours. This is verified by the constrained regularization method. The ‘normal’ colon tissues are usually characterized by a single, relatively narrow distribution, while tumours show one or more broad peaks. A substantial broadening of the distribution of relaxation times is observed in colon tumours, whether metastasized or not. A similar broadening is noted for breast tumours and malignant lymph nodes, although the range is slightly less than for colon tumours. The distribution of the transverse relaxation times reflects the biological (and chemical) heterogeneities of cancer cells and disorder in the tumour tissue. This approach to a more precise representation of the relaxation profile should allow better design of experimental conditions for the optimal visualization of tumours by 1H MRI.
What are the goals of magnetic resonance research?
Authors: Chance Britton
Published: March 2007

Now that both magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) have reached their decadic majority, appropriate questions may be asked as to their accomplishments and prognostications for the future. This article emphasizes the approach of the metabolic biologists/physiologists to magnetic resonance biochemistry as indicated by the currently available multinuclear localized approaches. The viewpoint is emphasized that MRS is a critical care instrument where precipitious changes of oxidative metabolism lead to the well‐known stroke, heart failure, liver failure, kidney failure, etc. Generally, the gradation between the classical metabolic steady state of life and the pathway leading to cell death is a narrow one and magnetic resonance in some cases is too finely tuned to delineate the gradations of stability and instability of cell metabolism. To this point, magnetic resonance can be supplemented by other modalities that sense tissue distress. An example of a most useful and predictive measure of hypoxic stress is optical spectrophotometry which uses time resolved ranging methods to measure optical path lengths to quantitate hemoglobin deoxygenation in tissues. With such a complement, the two methods emerge as one of general importance in diagnostic procedures.
Localized NMR spectroscopy In vivo. Progress and problems
Authors: Frahm Jens , Michaelis Thomas , Merboldt Klaus‐Dietmar , Hänicke Wolfgang , Gyngell Michael L. , Chien Daisy , Bruhn Harald
Published: March 2007

Metabolites in brain and muscle of normal human volunteers have been studied by localized 1H and 31P NMR spectroscopy in vivo. Localization was achieved by means of stimulated echo (STEAM) sequences for both water‐suppressed 1H NMR (TE = 20 ms) and 31P NMR (TE = 3 ms). Volumes‐of‐interest and measuring times selected for brain spectroscopy were 8 mL and 6.5 min for 1H NMR and 125 mL and 13 min for 31P NMR, respectively. General problems relating to spatial localization, spectral resolution, and quantitation of in vivo NMR data are discussed with respect to the nucleus and organs under investigation. They are correlated to studies of tissue extracts obtained at field strengths of 2.35 T (Bruker Biospec) and 7.0 T (Bruker MSL 300). Human studies were performed at 2.0 T on a whole‐body research system (Siemens Magnetom).
Brain metabolites as 1H NMR markers of neuronal and glial disorders
Authors: Gill S. S. , Small R. K. , Thomas D. G. T. , Patel P. , Porteous R. , Van Bruggen N. , Gadian D. G. , Kauppinen R. A. , Williams S. R.
Published: March 2007

1H NMR spectroscopy of human brain in vivo can be used to detect a number of cerebral metabolites including N‐acetylaspartate, creatine + phosphocreatine and choline‐containing compounds. We have used 1H NMR spectroscopy to analyse these signals in (i) biopsy material from both normal human brain and astrocytomas, and (ii) primary astrocyte cultures. On the basis of this analysis, we conclude that in vivo 1H NMR spectroscopy could play an important clinical role in the non‐invasive assessment of neuronal degeneration and proliferation of non‐neuronal cells.
Comparison of single‐shot localization methods (steam and press) for In vivo proton NMR spectroscopy
Authors: Moonen Chrit T. W. , Kienlin Markus Von , Van Zijl Peter C. M. , Cohen Jack , Gillen Joe , Daly Peter , Wolf Gerald
Published: March 2007

Two single‐shot localization techniques, STEAM and PRESS, are analyzed with regard to specifications for in vivo localized proton NMR. In particular, attention is paid to optimum signal intensity per unit volume, sensitivity to motion and diffusion, shortest attainable echo time, water suppression and editing possibilities. Experimental results are shown for cat brain at 4.7 T and human brain at 1.5 T. Both STEAM and PRESS are highly effective localization methods. For long echo times, PRESS is the method of choice, because it offers a factor of two gain in signal intensity. In addition, the method is less sensitive to motion and diffusion, and not susceptible to multiple‐quantum effects. STEAM offers advantages for observation of (coupled) metabolites with short T2, because (a) shorter TEs can be attained and (b) effective water suppression sequences can be implemented without penalty in echo time. Differences relating to editing possibilities and B1 dependence, possibly important in choosing a method, are discussed.
1H NMR study of cerebral development in the rat
Authors: Bates T. E. , Williams S. R. , Gadian D. G. , Bell J. D. , Small R. K. , Iles R. A.
Published: March 2007

1H NMR spectroscopy of brain extracts was used to investigate the metabolic changes that take place during development of the neonatal rat brain. Data were obtained over the range 1–21 days. The concentration of N‐acetylaspartate rose by a factor of 9 during this period, the most rapid rise occurring after day 9. The total creatine concentration rose from days 1–21, with a large increase between days 1 and 5. Taurine concentration rose until day 5, then fell from days 5–21. The concentration of choline‐containing compounds fell during the 21 day period. The results are discussed in relation to brain development and conventional biochemical data. A major conclusion in relation to spectroscopy of children is that interpretation of changes seen in disease will require adequate data from age‐matched controls.
1H spectroscopic imaging at high spatial resolution
Authors: Posse Stefan , Aue W. P.
Published: March 2007

Spectroscopic imaging and single voxel localization are compared with respect to the signal to noise ratio per unit time and unit volume. It is shown experimentally that, when using the same experiment time and the same voxel size, both methods give similar results. In order to investigate the localization limits of spectroscopic imaging, lipid distribution in a single large cell was measured and correlated with gradient echo microscopy.
NMR studies of body fluids
Authors: Bell Jimmy D. , Brown Judith C. C. , Sadler Peter J.
Published: March 2007

High resolution, high frequency, in vitro, proton NMR spectra of various body fluids, including urine, sweat, aqueous humour, amniotic fluid, seminal plasma, cerebrospinal fluid, synovial fluid and blood plasma are described and discussed. Applications include the detection of metabolic disorders, investigations of the biochemical basis of drug and xenobiotic metabolism, organ damage, and diagnoses for sick babies. The determination of metabolite concentrations is straightforward for fluids with a low protein content such as urine. In fluids with a high protein content such as blood plasma, it is possible to detect not only small molecules but also mobile regions of macromolecules, and to demonstrate the interaction of anions such as lactate with proteins. It seems likely that these methods will soon become established in modern pathology laboratories.
Multilabeled 13C substrates as probes in In vivo13C and 1H NMR spectroscopy
Authors: Künnecke Basil , Cerdan Sebastian
Published: March 2007

The potential use of 13C multilabeled substrates has been studied in biological applications using in vivo and in vitro proton and 13C NMR spectroscopy. In 13C NMR spectroscopy, multilabeled compounds allow the simultaneous observation of several nuclei or increase distinctly the signal to noise ratio due to a higher degree of enrichment. Contiguous labeling of substrates leads to homonuclear 13C‐13C spin couplings and provides a simple means to distinguish between endogenous stores of metabolites and metabolites derived from added substrates.
Absolute quantitation of neonatal brain spectra acquired with surface coil localization
Authors: Cady Ernest B. , Azzopardi Denis
Published: March 2007

Surface coils with strong coupling for both 31P and 1H were used to measure metabolite concentrations by in vivo NMR spectroscopy. Tissue water was used as an internal concentration reference and the 31P and 1H spatial sensitivities of the coils were matched. For such coils, sample loading does not necessarily have a significant effect on absolute quantitation results. The coils had proportionality constants which were almost independent of loading and the 1H and 31P flip angles at the coil centre produced by fixed length pulses were approximately equal over the range of loading conditions encountered in vivo. For 7 normal infants, of gestational plus postnatal age (GPA) 35 to 37 weeks, the nucleotide triphosphate concentration in the cerebral cortex was 3.7 ± 0.6 mmol/L wet tissue (mean ± SD). Further studies of normal infants down to 26 weeks GPA indicated that phosphorus metabolite concentrations increased significantly with GPA during this period. Concentrations were often low in the cerebral cortices of birth asphyxiated infants. In order to provide corroboration for the results from neonatal brain, data were acquired also from the resting, unexercised forearm muscles of 6 young adults and the measured adenosine triphosphate concentration was 6.3 ± 0.8 Mmol/L wet tissue.
NMR methods for measuring membrane transport rates
Authors: Kirk Kiaran
Published: March 2007

NMR methods for measuring membrane transport rates rely in most cases upon there being a significant transmembrane difference in either the resonance frequency or the NMR relaxation times of the transported species. The first part of this review examines the various factors that can give rise to such differences in cell and vesicle suspensions. The second part provides an introduction to the theory of membrane transport measurements and describes the different ways in which transmembrane differences in NMR parameters have been exploited in monitoring both slow and fast membrane transport processes.
Non‐invasive quantitation of human liver metabolites using image‐guided 31p magnetic resonance spectroscopy
Authors: Meyerhoff Dieter J. , Karczmar Gregory S. , Matson Gerald B. , Boska Michael D. , Weiner Michael W.
Published: March 2007

Phosphorus‐containing metabolites in normal human liver have been quantitated non‐invasively with 31P magnetic resonance spectroscopy using surface coils. The location of the volume of interest (VOI) was defined by 1H magnetic resonance imaging. Subsequently, a modified three‐dimensional localization technique (ISIS) was used to acquire 31P magnetic resonance spectra from the VOI. To account for partial saturation produced by rapid signal averaging, the spin/lattice relaxation times (T1) of all hepatic phosphorus resonances were measured. The corrected resonance integrals were used to derive absolute molar concentrations for the following hepatic metabolites (mmol/kg wet weight): ATP, 2.0; inorganic phosphate, 2.1; phosphodiesters, 5.4; and phosphomonoesters, 0.9. These values are compared with previously reported values for humans using freeze‐clamping techniques, and provide a basis for comparison with studies of hepatic disease in this laboratory.
Effect of photodynamic therapy on RIF‐1 tumor metabolism and blood flow examined by 31P and 2H NMR spectroscopy
Authors: Mattiello James , Evelhoch Jeffrey L. , Brown Eileen , Schaap A. Paul , Hetzel Fred W.
Published: March 2007

Photodynamic therapy utilizes the tumor localizing drug dihematoporphyrin ether and red laser light to produce both direct tumor cell destruction via damage to mitochondrial membranes, and also indirect cell kill via destruction of the tumor vasculature. As a first step towards examining the mechanistic relationship between metabolic and vascular effects of photodynamic therapy, murine RIF‐1 tumors were treated with a subcurative treatment (500J/cm2). Tumor metabolic status was monitored using in vivo 31P NMR before, during and after the treatment. The tumor blood flow immediately before and after treatment was measured by direct intratumor injection of D2O saline and observation of the tracer signal clearance from the tumor via 2H NMR. During the photodynamic therapy treatment, significant decreases were observed for the nucleoside triphosphate concentrations, tumor pH and tumor blood flow, while inorganic phosphate concentrations increased. Animals treated with laser light alone and those not given any treatment, demonstrated no significant changes in tumor metabolic status, tumor pH or tumor blood flow. Further studies are required to determine whether tumor blood flow or metabolic status is affected first.
Dynamics of skeletal muscle energetics during ischemia and reperfusion assessed by in vivo31P NMR
Authors: Soussi B. , Idström J.‐P. , Bylund‐Fellenius A.‐C. , Scherstén T.
Published: March 2007

The dynamics of rat skeletal muscle energy metabolism in response to ischemia and reperfusion have been investigated by in vivo 31P NMR spectroscopy. The time course of changes in the phosphocreatine, inorganic phosphate, ATP peaks and in intracellular pH during 2 and 4 h of tourniquet ischemia followed by up to 24 h of tissue reperfusion have been determined. Furthermore, the ATP and IMP concentrations in the soleus and tibialis muscles have been determined by high performance liquid chromatography analysis in response to ischemia and subsequent reperfusion. The results demonstrate an initial overshoot in the pH during the first minutes of ischemia. It is also shown that the muscles recover completely after 2 h of ischemia whereas the energy state of the muscle cell is not restored after 4 h of ischemia followed by up to 24 h of reperfusion. However, the soleus muscle recovers better than the tibialis. The results are discussed in terms of oxygen availability, reperfusion injury, IMP accumulation and different response between muscles with different fibre composition.
31P NMR studies of cultured human tumor cells. Influence of ph on phospholipid metabolite levels and the detection of cytidine 5′‐diphosphate choline
Authors: Kuesel A. C. , Graschew G. , Hull W. E. , Lorenz W. , Thielmann H. W.
Published: March 2007

202 MHz 31P NMR (11.7 T) was used to study the effects of culture medium pH on the levels of phosphate metabolites in three human tumor cell lines (XP29MAmal, a malignant xeroderma pigmentosum; CX‐1, a colon carcinoma; KB, a squamous cell carcinoma of the oral cavity). Cells were cultured in Roux flasks in HAM's F‐12 medium, and the pH was varied with the final medium change. After harvesting, 1–5 × 108 cells were suspended in Ringer/HEPES buffer at pH 7.4 and 4°C for 31P NMR studies. Cell adhesion and growth rate decreased with decreasing pH, but, down to ca pH 6.1, trypan blue exclusion and the observed levels of nucleoside di‐ and triphosphates (range: 22–37% of total phosphates detected), phosphocreatine (PCr, 2–5%) and Pi (5–11%) did not vary significantly with pH. For XP29MAmal cells in exponential growth phosphocholine levels decreased from 18–28% at pH 7.0 to ca 5% at pH 6.0, while phosphoethanolamine levels increased from 2–7% to 15%. Glycerophosphocholine (GPC) levels increased from ca 7% at pH 7.2 to 13% at pH 6.3. At pH<6.3 cytidine 5′‐diphosphate (CDP) choline became detectable (8–16%, δP: Pα = −8.13 ppm, Pβ = 8.93 ppm, for PCr = 0 ppm). However, confluent cells did not accumulate CDP‐choline when the pH was lowered. The cell lines CX‐1 and KB also showed the pH effects described herein.
31P NMR study of cisplatin‐ and doxorubicininduced changes in tumour metabolism in rats with a cisplatin‐sensitive or ‐resistant immunocytoma
Authors: Sijens P. E. , van Echteld C. J. A. , van Rijssel R. H. , Lagendijk J. J. W. , Neijt J. P. , de Jong W. H. , van der Minnen A. C. E. , de Groot G. , Seijkens D.
Published: March 2007

The response of tumours to treatment with the cytostatic drugs cisplatin (CDDP) or doxorubicin (DXR) was followed in vivo by 31P NMR spectroscopy. A CDDP‐sensitive parent line (IgM‐I) and a CDDP‐resistant subline (IgM/CDDP) of the IgM‐immunocytoma grown s.c. on LOU/M WsL rats were used. Animals from both tumour groups (n = 33) were divided into 3 subgroups: CDDP‐treated (1 mg/kg), DXR‐treated (10 mg/kg) and control. In 3 out of the 4 treated subgroups where the tumours regressed to less than one half of the initial size, 31P NMR spectroscopy revealed alkaline shifts of 0.31–0.41 pH units at day 4, while the ratio of nucleoside triphosphate to Pi in the tumours, increased continuously to 250–435%. Following CDDP treatment, the 31P NMR spectra of the non‐responding IgM/CDDP tumours showed a similar pH increase (0.37 units). The ratio of NTP/Pi showed a temporary decrease to 63 ± 14% SEM at day 1, which was followed by a recovery to 130 ± 12% at day 2 and 119 ± 15% at day 4. The control tumours showed no change in pH and a gradual decrease in the ratio of NTP/Pi. In DXR‐treated rats the concentrations of DXR in the immunocytoma tumour and its subline were similar, but in the CDDP‐treated rats the IgM‐I tumours contained significantly higher levels of platinum than the IgM/CDDP tumours, both measured at 3 and 4 days after administration. The continuous increase in NTP/Pi ratio observed in the responding tumours, is a phenomenon characteristic of tumour regression, while the early temporary decrease in tumour NTP/Pi ratio could be associated with resistance to CDDP. Whether the reported response‐specific spectral change applies to other tumour types and other treatment regimens remains to be established.
Effect of ethanol on hepatic energy metabolism and intracellular pH in chronically ethanol‐treated rats. A 31P NMR study of normoxic or hypoxic perfused liver
Authors: Desmoulin Franck , Canioni Paul , Masson Serge , Gérolami André , Cozzone Patrick J.
Published: March 2007

31P Nuclear magnetic resonance spectroscopy has been used to investigate the combined effect of 70 mM ethanol administration and hypoxia on the energetic metabolism and cytosolic pH of the perfused liver isolated from naive, fasted or chronically ethanol‐treated rats. Ethanol‐treatment or fasting induce a similar 25% reduction in ATP levels, and a differential enhancement of Pi levels to 130% and 225% of control values, respectively. In the naive rats, acute ethanol administration triggers profound variations in high‐energy phosphorylated metabolite levels with, in particular, a 300% increase in phosphomonoesters, mostly due to sn‐glycerol‐3‐phosphate (G3P) accumulation. A 4 min hypoxic period in the presence of ethanol induced a further accumulation of G3P. In the livers from chronically ethanol‐treated rats, the G3P level remains low during acute ethanol administration, despite the presence of glycogen, indicating an attenuation of the ethanol‐induced redox shift. The combination of 70 mM ethanol and hypoxia leads to an increased G3P level in the livers of chronically ethanol‐treated rats which is consistent with a sustained alcohol dehydrogenase activity. The subsequent cytosolic acidosis is significantly less pronounced in the chronically ethanol‐treated rats than in naive rats. These observations illustrate the adaptation of metabolic processes occurring in the livers of chronically ethanol‐treated rats, which results in an increased resistance to acute ethanol exposure and hypoxic stress.
Multiple quantum filtered 23Na NMR spectroscopy in the perfused heart
Authors: Payne Geoffrey S. , Seymour Anne‐Marie L. , Styles Peter , Radda George K.
Published: March 2007

It has been proposed that multiple quantum filtered (MQF) 23Na NMR spectroscopy may distinguish between sodium in the intra‐ and extracellular spaces, in vivo, and without the requirement for toxic shift reagents. We have investigated the origin of such signals in perfused rat hearts, using shift reagents to discriminate between NMR signals from the two compartments. We find that the observed MQF signal arises predominantly from the extracellular space in the normal heart, and from the intracellular space in the ischaemic heart. However, the quenching effect of the shift reagent may hide some of the extracellular MQF signal, especially during ischaemia. Estimates of intracellular and extracellular relaxation times are obtained and possible mechanisms of the interaction discussed.
Pattern recognition analysis of high resolution 1H NMR spectra of urine. A nonlinear mapping approach to the classification of toxicological data
Authors: Gartland K. P. R. , Sanins S. M. , Nicholson J. K. , Sweatman B. C. , Beddell C. R. , Lindon J. C.
Published: March 2007

A computer‐based pattern recognition (PR) approach has been applied to the interpretation of 1H NMR generated urinalysis data in a variety of experimental toxicity states in the rat. 1H NMR signal intensities for each endogenous metabolite in urine were regarded as coordinates in multi‐dimensional space and analysed using computer pattern recognition methods through which the dimensionality was reduced for display and categorization purposes. Initially 17 metabolic dimensions were used which were defined by the scored relative concentrations of a variety of urinary metabolites detected in 1H NMR spectra. By employing the unsupervised learning methods of 2‐ and 3‐dimensional nonlinear mapping (NLM) different types of toxin (hepatotoxins, cortical and papillary nephrotoxins) could be classified according to NMR‐detectable biochemical effects in the urine. The robustness of the classification methods, and the influence of the addition of new scored biochemical data reflecting dose response situations, nutritional effects on toxicity, sex differences in biochemical response to toxins and addition of a new toxin class (testicular toxin) to the pattern recognition analysis were also evaluated. We find that the initial training set maps are fundamentally stable to the addition of all data types and that the PR methods correctly ‘predicted’ the toxicological effects of the test compounds. These results confirm the power and wide applicability of linked PR and 1H NMR urinalysis as an approach to the generation and classification of acute toxicological data.
Renal distribution and metabolism of [2H9]choline. A 2H NMR and MRI study
Authors: Eng John , Berkowitzt Bruce A. , Balaban Robert S.
Published: March 2007

Trimethylamines are required as substrates in the biosynthesis of a number of important molecules in the cell. Herein, we describe the use of choline, deuterated in its 9 methyl positions, as an NMR label for following the distribution and metabolism of methyl groups after intravenous choline infusion. Deuterium (2H) NMR spectroscopy of the rabbit kidney in vivo revealed a linear uptake of infused choline that was directly proportional to the rate of infusion. The sensitivity limit for the spectroscopic studies in vivo was in the order of 100 μM for a 2 min data collection. After the infusion, 2H NMR imaging of the kidney in vivo demonstrated high trimethylamine concentrations in both the cortex and inner medulla but not in the outer medulla. The inner medullary fraction, however, was more labile to diuresis induced by furosemide. Companion high resolution 2H NMR studies of extracts revealed a cortex betaine/choline concentration ratio of 0.69 ± 0.05 (mean ± SEM, n = 3) before furosemide administration. Following furosemide infusion, the cortex betaine/choline concentration ratio was 3 ± 1 (n = 6). Thus, 2H renal images following furosemide treatment can be interpreted as metabolic maps of betaine distribution. In addition, extraction studies revealed high concentrations of labelled choline and betaine in the liver. These data demonstrate that 2H‐labelled choline is an effective marker of choline methyl metabolism in vivo and should provide a unique tool for the investigation of this important substrate.
The combined measurement of blood flow and metabolism in RIF‐1 tumours in vivo. A study using H2 flow and 31P NMR spectroscopy
Authors: Bhujwalla Z. M. , Tozer G. M. , Field S. B. , Proctor E. , Busza A. , Williams S. R.
Published: March 2007

Blood flow and phosphorus metabolites have been measured simultaneously in the murine RIF‐1 tumour in vivo. Blood flow was measured using the H2 washout technique and 31P NMR spectroscopy was used to measure high energy phosphates, inorganic phosphate and intracellular pH within the tumour. Following NMR and flow measurements, hydralazine was administered and the measurements repeated. There was always a decrease in blood flow, and a fall in nucleoside triphosphate detected by NMR, after administration of hydralazine. At blood flows in excess of 15 mL 100 g−1 min−1 the nucleoside triphosphate/inorganic phosphate ratio was 1.0 or greater, whereas at flows in the range of 5–12 mL 100 g−1 min−1 the ratio fell to below 0.5, and at flows below 5 mL 100 g−1 min−1 there was no detectable resonance from nucleoside triphosphate.
A 31P study of fatigue and metabolism in human skeletal muscle with voluntary, intermittent contractions at different forces
Authors: Newham D. J. , Cady E. B.
Published: March 2007

Normal subjects performed voluntary, isometric exercise (1 s contraction, 1 s rest for 10 min) of the first dorsal interosseous (FDI) muscle with a target force of 25, 50 and 100% of the maximal voluntary contraction (MVC) force. 31P NMR spectra were collected continuously before, during and after exercise. Data were also taken from the resting muscles 2‐28 h after the studies at 50% MVC. Calculations were made of the intracellular pH and concentrations of PCr, Pi, ATP, ADP and H2PO. The 25% MVC contractions did not affect the MVC, but those at 50 and 100% MVC reduced the force by 20% and 60%, respectively (p < 0.005). During the highest force contractions, the MVC declined from the first minute but the target forces of 25 and 50% were maintained throughout. All protocols caused significant changes in pH, PCr, Pi, ADP and H2PO. Exercise at 50% MVC caused greater metabolic changes than that at 25%, but there was no overall difference in the pH and phosphorus metabolites between the two higher forces. In parallel studies, electrical stimulation of the muscle indicated that during the voluntary contractions with a target force of 100% MVC in the magnet: (a), additional muscles were being used to generate the recorded force; and (b), the subjects were not fully activating the FDI. There was no obvious causal relationship between any one metabolite and the decline of force. Resting muscle showed an increase in the Pi peak 2–28 h after exercise at 50% MVC force, despite the muscles being of full strength and pain free.
Proton magnetic resonance spectroscopy of small regions (1 mL) localized inside superficial human tumors. A clinical feasibility study
Authors: van Zijl Peter C. M. , Moonen Chrit T. W. , Gillen Joe , Daly Peter F. , Miketic Linda S. , Frank Joseph A. , Delaney Thomas F. , Kaplan Ofer , Cohen Jack S.
Published: March 2007

It is demonstrated that the stimulated echo technique for proton magnetic resonance spectroscopy (MRS) can be used to study metabolites in volumes of interest (VOls) as small as 1 mL localized within superficial human tumors. Access to these small VOls is important for characterization of tissue regions within a tumor, before, during and after treatment. Spectral appearance resembles that from studies on extracts, and cell suspensions and perfused cells of several tumor types. For the first time proton MRS was used to study cancer treatment in vivo in humans, for a case of radiation treatment of squamous cell carcinoma. No spectral evidence of changed metabolism prior to reduction in tumor size was found. However, after the first period of radiation (39 Gy, 4 weeks), complete disappearance of the metabolite resonances from the spectrum was observed, while a considerable mass still remained, suggesting effective cell destruction upon treatment. Needle aspiration cytology of this mass showed absence of malignant cells, supporting this result.
31P spectroscopy in experimental embolic stroke: Correlation with infarct size
Authors: Smith C. D. , Thomas G. S. , Kryscio R. J. , Markesbery W. R.
Published: March 2007

Serial 31P nuclear magnetic resonance spectra were acquired from the brain in 19 rats following microsphere embolization of the right internal carotid artery. The brains were sectioned and stained with 2,3,5‐triphenyltetrazoline chloride 6 h post‐embolization to visualize infarcted areas. There was a narrow dosage range for the effect of embolism measured by maximum decline in pH at 20 min, mortality, and infarct size. This narrow range effect may be due to occlusion of collateral channels by the 16 micron microspheres. There was a strong correlation between decline in pH at 20 min post‐embolization and infarct size (r2 = 0.76); this decline was the best early marker for eventual infarct in our study. This animal model for macroscopically heterogenous brain ischemia may be useful for the evaluation of therapeutic interventions in stroke, and as an aid in the interpretation of phosphorus spectra from mixed volumes of ischemic and non‐ischemic brain.
Nuclear magnetic resonance determination of flow, lactate, and phosphate metabolites during amphetamine stimulation of the rat brain
Authors: Detre John A. , Williams Donald S. , Koretsky Alan P.
Published: March 2007

The effects of amphetamine on rat cerebral blood flow, lactate, and phosphate levels were studied using in vivo nuclear magnetic resonance (NMR) spectroscopy. Proton NMR imaging was used to determine the region of brain being studied. Blood flow was estimated by detecting the washout of trifluoromethane using 19F NMR. A dose of 20 mg/kg D‐amphetamine sulphate stimulated flow fourfold over control values for at least 1 h. Even though amphetamine stimulated a large increase in flow, there were no significant changes in levels of inorganic phosphate, ATP, phosphocreatine, pH or Mg2+ as determined by 31P NMR. This was true for doses of 10 and 20 mg/kg D‐amphetamine sulphate. No significant changes occurred in 1H NMR detected levels of lactate with a 20 mg/kg dose of amphetamines. Lactate levels increased slightly 30min after administration of 10 mg/kg D‐amphetamine sulphate. The results call into question the central role of changes in levels of phosphates in coupling increased cortical activity to increases in metabolism.
A quantitative analysis of the accuracy of In Vivo pH measurements with 31P NMR spectroscopy: Assessment of pH measurement methodology
Authors: Madden A. , Leach M. O. , Sharp J. C. , Collins D. J. , Easton D.
Published: March 2007

31P NMR spectroscopy provides a means of monitoring intracellular pH (pHi). In order to determine the significance of observed pH changes, an assessment of the measurement uncertainty is required. This paper considers the possible sources of error involved, firstly in chemical shift assignment and, secondly, in relating chemical shift to pH. A statistical analysis of these errors is presented and an expression for the accuracy of pH measurements obtained using in vivo 31P NMR spectroscopy is derived. Computer simulations and clinical measurements are considered to determine the likely error in clinical measurements. A comparison of pH measurement methodology using a centre‐of‐gravity calculation, Gaussian and Lorentzian fitting is also presented and discussed.
Acquisition and quantitation in proton spectroscopy
Authors: Luyten Peter R. , Mariën Ad J. H. , Den Hollander A.
Published: March 2007

Localized proton NMR spectroscopy in the human brain is one of the more technically advanced applications of human in vivo NMR spectroscopy. Spin/echo techniques introduced reliable localization procedures, whereas the introduction of phase encoding techniques improved the spatial information content considerably. Using the sensitivity of the 1H NMR signal, a spatial resolution of 7 × 7 × 15 mm can be obtained. Chemical shift images can be reconstructed to represent the choline, creatine, N‐acetyl aspartate and lactate distribution in the human brain. These low resolution images may be used as a new functional imaging modality to visualize and derive quantitative biochemical information from focal brain lesions under normal and pathological conditions.
What the clinician can learn from MRS lactate measurements
Authors: Prichard James W.
Published: March 2007

Lactate is of special importance in brain metabolism. In the 1980s, noninvasive methods for measurement of lactate concentration and turnover rate in living brain by 1H and 13C NMR spectroscopy were implemented in both animals and humans, opening the way to innovative examination of lactate's role in normal and deranged brain function. Early data on elevation of lactate in human visual cortex by physiologic stimulation and turnover of pathologically elevated brain lactate pools in animals and humans suggest that the new methods are likely to benefit clinical practice both directly–by providing information useful in management of individual patients–and indirectly–through improved understanding of disease processes.
31P magnetic resonance spectroscopy is sensitive to tumor hypoxia: Perfusion and oxygenation of rat 9L gliosarcoma after treatment with BCNU
Authors: Grant Steen R. , Graham Michael M.
Published: March 2007

The 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/a nucleoside biphosphate) (p<0.01). Gamma camera imaging of 133Xe washout, following injection of 133Xe 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 tumor pO2 of sham‐treated tumors was 18.1 (±1.7 SE) mmHg (n = 00 measurements in six tumors) while mean pO2 of 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 tumor metabolic hypoxia.
Non‐invasive In Vivo localized 1H spectroscopy of human astrocytoma implanted in rat brain: Regional differences followed in time
Authors: Van Vaals J. J. , Bergman A. H. , Van Boogert H. J. Den , Heerschap A. , Van Kogel A. J. Der , Ruifrok A. C. C. , Bernsen H. J. J. A.
Published: March 2007

Human astrocytoma cells were cultured and inoculated into the rat brain. From the pre‐clinical to the terminal state, tumour growth was monitored by in vivo MR imaging and by localized water‐suppressed 1H spectroscopy (0.12‐0.15 cm3 volumes) and spectroscopic imaging (0.01 cm3 voxels) 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 of N‐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 localized 1H 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 evaluation.
13C NMR spectroscopic analysis of phospholipid metabolism in adrenal chromaffin cells
Authors: Rivera Carlos J. , Plishker Gordon A. , Morrisett Joel D. , Moore John , Percy Alan K.
Published: March 2007

Phosphatidylcholine (PC) metabolism in bovine adrenal chromaffin cells has been studied in vivo with 100 MHz 13C NMR spectroscopy. The incorporation of 13[CH3]choline was examined in cells embedded in 1% agarose strands and perfused at 37 °C. The pattern of 13C 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 the in vivo metabolism of PC in functioning adrenal chromaffin cells