bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractIn 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

AbstractNow 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

AbstractMetabolites 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

Abstract1H 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

AbstractTwo 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

Abstract1H 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

AbstractSpectroscopic 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

AbstractHigh 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

AbstractThe 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

AbstractSurface 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

AbstractNMR 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

AbstractPhosphorus‐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

AbstractPhotodynamic 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

AbstractThe 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

Abstract202 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

AbstractThe 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

Abstract31P 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.