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  • 1
  • 2
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  Jahrestagung der Gesellschaft für Medizinische Ausbildung (GMA); 20100923-20100925; Bochum; DOC10gma38 /20100805/
    Publication Date: 2010-08-06
    Keywords: ddc: 610
    Language: German
    Type: conferenceObject
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  • 3
    Keywords: ENERGIES ; SPECTRA ; Germany ; human ; IN-VIVO ; VIVO ; SYSTEM ; SYSTEMS ; TISSUE ; ACCURACY ; FREQUENCY ; FIELD ; H-1 ; INVIVO ; SPECTROSCOPY ; FORM ; DIFFERENCE ; ENERGY ; NMR-SPECTROSCOPY ; MUSCLE ; SKELETAL-MUSCLE ; ORIENTATION ; H-1 NMR ; carnosine,in vivo H-1 NMR,human calf muscle,second-order spectra,Breit-Rabi formula ; HUMAN SKELETAL-MUSCLE ; INTRACELLULAR PH ; LACTATE ; ORIGIN ; POSTMORTEM ; PROTON MR SPECTROSCOPY
    Abstract: Spin systems with residual dipolar couplings such as creatine, taurine, and lactate in skeletal muscle tissue exhibit first-order spectra in in vivo H-1 NMR spectroscopy at 1.5 T because the coupled protons are represented by (nearly) symmetrized eigenfunctions. The imidazole ring protons (H2, H4) of carnosine are suspected to form also a coupled system. The ring's stiffness could enable a connectivity between these anisochronous protons with the consequence of second-order spectra at low field strength. Our purpose was to study whether this deviation from the Paschen-Back condition can be used to detect the H2-H4 coupling in localized 1D H-1 NMR spectra obtained at 1.5 T (64 MHz) from the human calf in a conventional whole-body scanner. As for the hydrogen hyperfine interaction, a Breit-Rabi equation was derived to describe the transition from Zeeman to Paschen-Back regime for two dipolar-coupled protons. The ratio of the measurable coupling strength (Sk) and the difference in resonance frequencies of the coupled spins (Deltaomega) induces quantum-state mixing of various degree upon definition of an appropriate eigenbase of the coupled spin system. The corresponding Clebsch-Gordan coefficients manifest in characteristic energy corrections in the Breit-Rabi formula. These additional terms were used to define an asymmetry parameter of the line positions as a function of Sk and Deltaomega. The observed frequency shifts of the resonances were found to be consistent with this parameter within the accuracy achievable in in vivo NMR spectroscopy. Thus it was possible to identify the origin of satellite peaks of H2, H4 and to describe this so far not investigated type of residual dipolar coupling in vivo. (C) 2003 Elsevier Inc. All rights reserved
    Type of Publication: Journal article published
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  • 4
    Keywords: SPECTRA ; human ; IN-VIVO ; VIVO ; IMAGES ; imaging ; INFORMATION ; METABOLISM ; DIFFERENTIATION ; TISSUE ; MARKER ; REDUCTION ; SIGNAL ; MAGNETIC-RESONANCE-SPECTROSCOPY ; STAGE ; PATTERNS ; NMR ; MARKERS ; PCR ; DAMAGE ; REGION ; REGIONS ; LOCALIZATION ; MUSCLE ; PARAMETERS ; SKELETAL-MUSCLE ; ATROPHY ; FEASIBILITY ; INFILTRATION ; LEVEL ; in vivo ; SIGNALS ; ACCESS ; H1 ; ADJACENT ; NECROSIS ; DEGENERATION ; atrophic muscle ; DENERVATION ; H-1 spectroscopy ; HUMAN-CALF-MUSCLE ; P-31 spectroscopic imaging ; REINNERVATION
    Abstract: Introduction The purpose of this feasibility study was to demonstrate non-invasive metabolic imaging of human muscular atrophy using significant changes of NMR signals that are related directly or indirectly to fiber necrosis. Methods Single-voxel H-1 NMR spectroscopy and two-dimensional P-31 spectroscopic imaging on a 1.5-T whole-body scanner were used for in vivo mapping of areas of muscle damage in two cases of differently localized and pronounced atrophy. Spectral patterns affiliated with severe and intermediate stages of degeneration were compared to data of healthy control tissue to derive appropriate metabolic markers related to lipid infiltration or high-energy P-31 metabolism. Results Reliable detection of atrophic tissue was achieved by the following parameters: ( 1) liposclerotic turnover is related to a drastic reduction in the water/lipid H-1 signal intensity ratio ( up to a factor of 74 compared to adjacent healthy tissue); ( 2) the P-31 resonance of phosphocreatine (PCr) is an adequate marker for differentiation of intact myocells with high-energy metabolism from regions dominated by terminal fiber necrosis ( PCr signal vanished nearly completely or intensity was reduced by a factor of 3 in affected muscles). Metabolic images based on this signal allowed accurate non-invasive localization of atrophic tissue. Conclusion The molecular information provided by NMR spectroscopy - previously only used with poor localization in atrophy studies - enables access to both the myocell-specific high-energy metabolism and the result of lipid infiltration allowing non-invasive mapping of degenerate tissue. The ability to investigate the results of these advanced levels of atrophy would also be useful for studies of more subtle degrees of denervation
    Type of Publication: Journal article published
    PubMed ID: 17031631
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  • 5
    Keywords: SPECTRA ; Germany ; human ; IN-VIVO ; VIVO ; INFORMATION ; QUANTIFICATION ; SYSTEM ; SYSTEMS ; TISSUE ; DYNAMICS ; FIELD ; magnetic resonance ; MAGNETIC-RESONANCE ; MAGNETIC-RESONANCE-SPECTROSCOPY ; METABOLITES ; SPECTROSCOPY ; NMR ; NMR-SPECTROSCOPY ; LINE ; PARAMETERS ; PREDICTION ; IMMOBILIZATION ; METABOLITE ; MOLECULAR-DYNAMICS ; biosensor ; molecular ; review ; TRANSITION ; interaction ; SPINS ; muscle tissue ; carnosine ; human calf muscle ; analysis ; NUCLEAR ; MECHANICS ; USA ; in vivo ; SPECTRUM ; magnetic resonance spectroscopy ; comparison ; RESONANCE ; German ; SHAPE ; TRANSITIONS ; CONSTRAINTS ; molecular dynamics ; Breit-Rabi equation ; H-1-NMR ; H-1-NMR SPECTROSCOPY ; hyperfine structure ; in vivo spectroscopy ; interactions ; P-31-NMR ; PHOSPHOCREATINE ; SPIN
    Abstract: The hyperfine interaction of two spins is a well studied effect in atomic systems. Magnetic resonance experiments demonstrate that the detectable dipole transitions are determined by the magnetic moments of the constituents and the external magnetic field. Transferring the corresponding quantum mechanics to molecular bound nuclear spins allows for precise prediction of NMR spectra obtained from metabolites in human tissue. This molecular hyperfine structure has been neglected so far in in vivo NMR spectroscopy but contains useful information, especially when studying molecular dynamics. This contribution represents a review of the concept of applying the Breit-Rabi formalism to coupled nuclear spins and discusses the immobilization of different metabolites in anisotropic tissue revealed by H-1 NMR spectra of carnosine, phosphocreatine and taurine. Comparison of atomic and molecular spin systems allows for statements on the biological constraints for direct spin-spin interactions. Moreover, the relevance of hyperfine effects on the line shapes of multiplets of indirectly-coupled spin systems with more than two constituents can be predicted by analyzing quantum mechanical parameters. As an example, the superposition of eigenstates of the AMX system of adenosine 5'-triphosphate and its application for better quantification of P-31-NMR spectra will be discussed
    Type of Publication: Journal article published
    PubMed ID: 17665732
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  • 6
    Keywords: AEROBIC CAPACITY, analysis, BIOPSIES, BIOPSY, BLOOD, blood volume, BLOOD-FLOW, BODIES, BODY, body we
    Abstract: PURPOSE To assess metabolism and microcirculation of healthy skeletal muscle by magnetic resonance (MR) and ultrasound techniques and to compare these data with muscle histology, and anthropometric and blood parameters. METHODS Thirty-four healthy volunteers were selected such that their measured aerobic capacity (VO(2)max) per body weight ranged between 23 and 66 mL/minute/kg to render a large variability of skeletal muscle capillarization as a result of their different physical activity. We analyzed body composition, blood parameters, and skeletal muscle fiber size and capillarization in biopsies of the vastus lateralis muscle. These data were compared with knee extensor cross-sectional area (CSA) obtained by MR imaging, microcirculation of the vastus lateralis muscle by contrast-enhanced ultrasound (CEUS), and its energy and lipid metabolism measured with P-31 and H-1 MR spectroscopy. Statistical analysis was performed using Pearson's correlation coefficient and significance was tested at a level of .5%. RESULTS The variable physical activity was reflected in a large variability of vastus lateralis muscle perfusion and metabolism at rest with highest histologic capillarization and CEUS-perfusion values observed in the best-trained volunteers. Levels of high-energy phosphates, such as phosphocreatine, were positively correlated with CSA (r = .5) and histologic fiber size (r = .6 for type IIA and IIX fibers), while phosphocreatine concentration was significantly negatively correlated to myocellular lipids (r = -.6) and trimethyl ammonium containing compounds (r = -.8). Local blood volume measured in vivo with CEUS was positively correlated with several histologic capillarization parameters. CONCLUSIONS Dedicated MR- and CEUS-methods deliver (patho-)physiologic information about capillarization and fiber characteristics of skeletal muscles in vivo and hence establish a useful diagnostic tool for muscular diseases
    Type of Publication: Journal article published
    PubMed ID: 17894621
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  • 7
    Keywords: DOMAIN ; MRI ; SPECTROSCOPY ; RECONSTRUCTION ; EXCHANGE SATURATION-TRANSFER ; SPARSITY
    Abstract: We describe a new MR imaging method for the rapid characterization or screening of chemical exchange saturation transfer (CEST) contrast agents. It is based on encoding the chemical shift dimension with an additional gradient as proposed in previous ultrafast CEST spectroscopy approaches, but extends these with imaging capabilities. This allows us to investigate multiple compounds simultaneously with an arbitrary sample tube arrangement. The technique requires a fast multislice readout to ensure the saturation is not lost during data acquisition due to T1 relaxation. We therefore employ radial subsampling, acquiring only 10 projections per CEST image with a 128x128 matrix. To recover the images, we use a heuristic reconstruction algorithm that incorporates low rank and limited object support as prior knowledge. This way, we are able to acquire a spectral CEST data set consisting of 15 saturation offsets more than 16 times faster than compared with conventional CEST imaging.
    Type of Publication: Journal article published
    PubMed ID: 24721681
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  • 8
  • 9
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  51. Kongress für Allgemeinmedizin und Familienmedizin; 20170921-20170923; Düsseldorf; DOC17degam058 /20170905/
    Publication Date: 2017-09-05
    Keywords: ddc: 610
    Language: German
    Type: conferenceObject
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  • 10
    Keywords: IN-VITRO ; human ; IN-VIVO ; VITRO ; QUANTIFICATION ; NEW-YORK ; TISSUE ; COMPLEX ; LIGAND ; IONS ; BIOLOGY ; MOLECULAR-BIOLOGY ; RELAXATION ; MUSCLE ; EXCHANGE ; SKELETAL-MUSCLE ; sensitivity ; REVEALS ; molecular biology ; molecular ; ANSERINE ; carnosine ; NUCLEAR ; USA ; AQUEOUS-SOLUTION ; comparison ; METAL-COMPLEXES ; ALANYL-L-HISTIDINE ; COPPER(II)-CARNOSINE COMPLEX ; Cu(II) chelation ; H-1 NMR spectroscopy ; HOMOCARNOSINE ; relaxation transfer
    Abstract: Complex formation of carnosine (Csn) with Cu(II) is suspected to be of significant biochemical importance and can be detected by NMR via ion-induced paramagnetic relaxation of Csn signals. Here, we present quantification of the sensitivity achieved with localized H-1 NMR spectroscopy at physiological pH and high ligand-to-metal ratios. While characterizing the highly effective relaxation transfer onto a huge Csn pool due to fast ligand exchange, it is demonstrated that a metal-to-ligand ratio of similar to 100 ppm suffices to reduce Csn signals by similar to 50% in vitro, thus making the dipeptide a sensitive probe for such ions. Variation of the donor accessibility reveals that the paramagnetic effect is transferred onto a similar to 1370-fold donor abundance for a given ion concentration. A method is presented to characterize such effective ligand exchange relaxation transfer. These studies focus on the monomer formation since comparison with H-1 NMR data of human calf muscle demonstrates that the dimer complex is insignificant in vivo. Observed line broadening in living tissue yields an upper limit of ca. 195 ppm for the Csn-related copper concentration in human skeletal muscle. (c) 2007 Elsevier Inc. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 17845819
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