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  • 1
    Electronic Resource
    Electronic Resource
    Specific Expression of N-Acetylaspartate in Neurons, Oligodendrocyte-Type-2 Astrocyte Progenitors, and Immature Oligodendrocytes In Vitro (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 59 (1992), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To test the specificity of N-acetylaspartate (NAA) as a neuronal marker for proton nuclear magnetic resonance (1H NMR) spectroscopy, purified and characterized cultured cells were analyzed for their NAA content using both 1H NMR and HPLC. Cell types studied included cerebellar granule neurons, type-1 astrocytes, meningeal cells, oligodendrocyte-type-2 astrocyte (O–2A) progenitor cells, and oligodendrocytes. A high concentration of NAA was found in extracts of cerebellar granule neurons (approximately 12 nmol/mg of protein), whereas NAA remained undetectable in purified type-1 astrocytes, meningeal cells, and mature oligodendrocytes. However, twice the neuronal level of NAA was found in O-2A progenitors grown in vitro. In addition significant levels of NAA were also detected in cultures of immature oligodendrocytes. Our data partly support previous suggestions that NAA may be a useful neuronal marker for 1H NMR spectroscopic examination of the adult brain. However, they also raise the further possibility that alterations of NAA associated with some specific brain disorders, particularly disorders seen in newborn and young children, may reflect abnormalities in the development of oligodendroglia or their precursors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1992.tb08875.x
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  • 2
    Electronic Resource
    Electronic Resource
    Detection of Mobile Proteins by Proton Nuclear Magnetic Resonance Spectroscopy in the Guinea Pig Brain Ex Vivo and Their Partial Purification (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 58 (1992), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Proton nuclear magnetic resonance (1H NMR) spectroscopy was used to study metabolites of the brain cortex ex vivo. The superfused brain cortex preparation was judged to be metabolically viable on the basis of the 31P NMR spectrum (intracellular pH of 7.23 ± 0.03 and phosphocreatine/ ATP ratio of 1.21 ± 0.09). Using‘H NMR a group of previously unidentified signals was detectable at 0.94, 1.22, and 1.40 ppm with a water-suppressed spin-echo sequence. These signals had shorter spin-spin relaxation times (51-54 ms) than TV-acetylaspartate and lactate (84-93 ms) and also smaller saturation factors, an indication of shorter spin-lattice relaxation times than the latter two low-molecular-weight metabolites. The unidentified signals also displayed homo-nuclear coupling to other spins in the methine region of the spectrum. Acid extraction of the brain slices or cortex from animals that were killed yielded a mixture of proteins that exhibited NMR properties matching the 1H NMR signals in the brain cortex. The molecular mass of these thermoresistant, “mobile’ proteins, which contained proline plus hydroxy-proline (9-16% of all amino acids), ranged between 8 and 40 kDa. These “new’ assigμMents of1H NMR-detectable compounds may influence interpretation of NMR data of some metabolites, as their signals are in the vicinity of the -CH3 1H NMR peaks of lactate and alanine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1992.tb09350.x
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  • 3
    Electronic Resource
    Electronic Resource
    Nondestructive Detection of Glutamate by 1H Nuclear Magnetic Resonance Spectroscopy in Cortical Brain Slices from the Guinea Pig: Evidence for Changes in Detectability During Severe Anoxic Insults (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 31P and 1H nuclear magnetic resonance spectroscopy (NMR) was used to study the metabolism of intact superfused cortical brain slices during normoxia and anoxia. Attention was focused on quantification of 1H NMR-detected glutamate by a water-suppressed spin-echo method, using N-acetyl aspartate as an internal concentration reference. To quantify the 1H NMR signals, the spin-spin relaxation times and saturation effects were estimated for given metabolites. In addition, absolute concentrations of metabolites were determined by biochemical methods from acid extracts of the preparations after NMR experiments. Under aerobic conditions, 1H NMR detected 79% of the glutamate determined biochemically from the brain slice extracts. During anoxia in the absence of glucose when a severe energetic failure was evident, both 1H NMR and biochemical assays gave closely matching levels for glutamate. We conclude that in the brain cortex 21% of glutamate is located in an intracellular compartment in which this amino acid does not contribute to the 1H NMR signal. However, during severe anoxia an intracellular reorganization occurs increasing the detectability of this amino acid neurotransmitter by NMR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb08271.x
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  • 4
    Electronic Resource
    Electronic Resource
    Observation of Cerebral Metabolites in an Animal Model of Acute Liver Failure In Vivo: A 1H and 31P Nuclear Magnetic Resonance Study (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 53 (1989), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Acute liver failure was induced in rats by a single intragastric dose of carbon tetrachloride. This causes hepatic centrilobular necrosis, as indicated by histological examinations, and produces a large increase in the activity of serum alanine aminotransferase. The plasma NH4+ level (mean ±SEM) was 123 ± 10 μM the control group and 564 ± 41 μM in animals with acute liver failure (each n = 5). 31P nuclear magnetic resonance (NMR) was used to monitor brain cortical high-energy phosphate compounds, Pi, and intracellular pH. 1H NMR spectroscopy was utilised to detect additional metabolites, including glutamate, glutamine, and lactate. The results show that the forebrain is capable of maintaining normal phosphorus energy metabolite ratios and intracellular pH despite the metabolic challenge by an elevated blood NH4+level. There was a significant increase in the brain glutamine level and a concomitant decrease in the glutamate level during hyperammonaemia. The brain lactate level increased twofold in rats with acute liver failure. The results indicate that 1H NMR can be used to detect cerebral metabolic changes in this model of hyperammonaemia, and our observations are discussed in relation to compartmentation of NH4+ metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1989.tb07300.x
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  • 5
    Electronic Resource
    Electronic Resource
    High Resolution Proton NMR Spectroscopy of Multiple Sclerosis Lesions (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 64 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Tissue from postmortem multiple sclerosis and normal control brains was extracted with perchloric acid and analysed using proton NMR spectroscopy. The content of N-acetyl-derived groups (the sum of N-acetylaspartate, acetate, and N-acetylaspartylglutamate) was decreased in multiple sclerosis plaques compared with normal control white matter (mean, 4.36 vs. 6.64 µmol/g wet weight). In normal appearing white matter adjacent to plaques a corresponding decrease was seen, with no change in white matter distant from plaques. A decrease in the content of total creatine was observed in multiple sclerosis plaques in comparison with normal control white matter (mean, 4.64 vs. 6.56 µmol/g wet weight), which correlated strongly with the decrease in N-acetyl-derived groups. No changes in other metabolites such as total choline or myo-inositol were seen. The decreases in content of N-acetyl-derived groups are in agreement with observations from in vivo proton NMR spectroscopy in multiple sclerosis patients. The decrease in total creatine is in contrast to most of the observations made in vivo where total creatine is assumed to be unchanged and metabolite levels are often expressed as a total creatine ratio. The use of a total creatine ratio in vivo could lead to an underestimation of reductions in N-acetylaspartate and an apparent increase in other metabolites in the multiple sclerosis lesion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.64020742.x
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  • 6
    Electronic Resource
    Electronic Resource
    Some Recent Applications of H NMR Spectroscopy in Vivo (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 508 (1987), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1987.tb32908.x
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  • 7
    Electronic Resource
    Electronic Resource
    31P NMR analysis of intracellular pH of Swiss mouse 3T3 cells: Effects of extracellular Na+ and K+ and mitogenic stimulation (1986)
    Springer
    The journal of membrane biology 94 (1986), S. 55-64 
    Details
    ISSN: 1432-1424
    Keywords: 2-deoxyglucose phosphate ; inorganic phosphate ; 19F NMR ; NMR probe configuration ; Na/H antiport ; vasopressin ; insulin ; epidermal growth factor ; microcarrier beads
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Swiss mouse 3T3 cells grown on microcarrier beads were superfused with electrolyte solution during continuous NMR analysis. Conventional31P and19F probes of intracellular pH (pH c ) were found to be impracticable. Cells were therefore superfused with 1 to 4mm 2-deoxyglucose, producing a large intracellular, pH-sensitive signal of 2-deoxyglucose phosphate (2DGP). The intracellular incorporation of 2DGP inhibited the Embden-Meyerhof pathway. However, intracellular ATP was at least in part retained and the cellular responsivity to changes in extracellular ionic composition and to the application of growth factors proved intact. Transient replacement of external Na+ with choline or K+ reversibly acidified the intracellular fluids. Quiescent cells and mitogenically stimulated cells displayed the same dependence of shifts in pH c on external Na+ concentration (c Na o ). pH c also depended on intracellular Na+ concentration (c Na o ). Increasingc Na c by withdrawing external K+ (thereby inhibiting the Na,K-pump) caused reversible intracellular acidification; subsequently reducingc Na o produced a larger acid shift in pH c than with external K+ present. Comparison of separate preparations indicated that pH c was higher in stimulated than in quiescent cells. Transient administration of mitogens also reversibly alkalinized quiescent cells studied continuously. This study documents the feasibility of monitoring pH c of Swiss mouse 3T3 cells using31P NMR analysis of 2DGP. The results support the concept of a Na/H antiport operative in these cells, both in quiescence and after mitogenic stimulation. The data document by an independent technique that cytoplasmic alkalinization is an early event in mitogenesis, and that full activity of the Embden-Meyerhof pathway is not required for the expression of this event.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01901013
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  • 8
    Electronic Resource
    Electronic Resource
    Anomalies of the pulmonary artery in necturus (1909)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 3 (1909), S. 409-414 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1090030704
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