K L Behar

..Thus, glutamine appears to play a central role in the normal functional energetics of the cerebral cortex...

..The aim of the study was to compare levels of neuroactive amino acids in the cerebral cortex of healthy subjects, recently detoxified alcohol-dependent patients, and patients with hepatic encephalopathy...

..These findings indicate that anaplerotic glutamine synthesis is coupled to nitrogen removal from the brain (ammonia detoxification) under hyperammonemic conditions...

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..Another implication of this result is that brain activation studies, which map cortical oxidative Glc metabolism, provide a quantitative measure of synaptic glutamate release...

..These findings bear upon a number of hypotheses concerning the neurophysiological basis of brain functional imaging methods...

..GAD(67) could account for 56-85% of cortical GABA synthesis flux under basal conditions and the entire flux after vigabatrin treatment...

..07 micromol/g) based on the average precursor enrichments between 1 and 3 h. We conclude that glutamine is the major source of GABA carbon in the rat neocortex produced acutely following GABA-T inhibition by gabaculine in vivo...

..In this study we used in vivo proton magnetic resonance spectroscopy to investigate the hypothesis that abnormalities in the GABA neurotransmitter system are associated with the neurobiologic processes of depression...

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..The purpose of the present work was to determine whether cortical GABA levels are abnormally low in patients with panic disorder...

..Consequences of these results from rat brain for similar calibrated BOLD fMRI studies in the human brain are discussed...

..Our findings indicate that SSADH deficiency is associated with major alterations in glutamate and glutamine metabolism in glia and neurons with surprisingly lesser effects on GABA synthesis...

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..Because they also correspond to the changes found in other dementias, including Alzheimer's disease and HIV dementia, these changes indicate converging pathogenetic pathways involved in many neurodegenerative diseases...

..These results strongly suggest that activation of voltage-dependent Na+ channels is involved in the BOLD fMRI responses during somatosensory activation of the rat cortex...

..These results indicate that neuronal glucose oxidation and not total glucose utilization is coupled to the glutamate/glutamine cycle during intense cortical activation...

..2004b)...

..In the current study, the authors tested the hypothesis that panic disorder patients have a deficient GABA neuronal response to benzodiazepine (clonazepam) administration...

..The contribution of GABAergic neurons and inhibition to cortical energy metabolism has broad implications for the interpretation of functional imaging signals...

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..The findings suggest that astroglia may be the site of continuing GABA catabolism after acute vigabatrin treatment...

..3-fold increase in inorganic phosphate, known to be a potent activator of apoGAD(65)in vitro. Our results are consistent with a major role for GAD(65) in activity-dependent GABA synthesis...

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..Early validation results, using magnetic resonance spectroscopic imaging as a gold standard, are encouraging. We also present results demonstrating differences in fat distribution between male and female mice...

..The findings show that glutamate and GABA neurons undergo large and approximately proportional increases in neurotransmitter cycling and oxidative energy metabolism during this major postnatal growth spurt...

..Unique spectral information which is normally not directly available from regular (1)H NMR spectra can be extracted and used for compound identification or improved prior knowledge during spectral fitting...

..74 T. The chemical shifts and line widths of more than 20 oxygen-containing metabolites are established and the sensitivity and potential for (17)O-enriched NMR studies are estimated...

..The relationship observed between DeltaCMR(glc(ox), N) and DeltaV(cyc(tot)) is determined by glial glycolytic ATP as before. Quantitative aspects of the model, which can be tested by experimentation, are discussed...

..02 +/- 0.04, and 0.18 +/- 0.12 micromol/min per g, respectively. The exchange rate between the mitochondrial and cytosolic metabolite pools was fast relative to the neuronal tricarboxylic acid cycle flux for all cerebral tissue types...

..MRS and fMRI experiments show that the majority of cerebral activity, which is often disregarded in imaging experiments, is ongoing even when the brain appears to be doing nothing...

..The further application of this approach could potentially enlighten the role of astroglia in supporting brain glutamatergic activity and in neurological and psychiatric disease...

..Because DeltaCMR(O2)/CMR(O2) had the same high spatial and temporal resolutions of the fMRI signal, these results show how BOLD imaging, when converted to DeltaCMR(O2)/CMR(O2), responds to localized changes in neuronal spike frequency...

..52 +/- 0.04 micromol/min/g, while the glutamatergic neurotransmitter flux equaled 0.25 +/- 0.05 micromol/min/g, in good correspondence with previously determined values...

..Here we review and discuss the importance of neurotransmission and neuroenergetics as measured by (13)C MRS for understanding brain function and interpreting fMRI...

..A two-scan RARE implementation provides sufficient spatial and temporal resolution for most applications. Quantitative mapping of T(1) relaxation and cerebral blood flow changes during forepaw stimulation in the rat are demonstrated...

..The general nature of diffusion-sensitized NMR spectroscopy allows application on a wide range of biological fluids...

..Finally, (1)H-[(13)C]-NMR spectroscopy allows the detection of energy metabolism and neurotransmission during functional activation, thereby further strengthening our understanding of the neurochemical basis of brain function...

..The regional variations in the basal awake state, which are expected to be even greater, should be considered to avoid partial-volume artifacts in functional activation studies of awake subjects...

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..The mechanism of this protection is likely related to a decrease in protein denaturation, through protein-trehalose interactions, resulting in enhanced cellular recovery from hypoxic stress...

..unpacking of erythrocytes, or increase vs. decrease of dissolved oxygen in the tissue (i.e., processes which modify vessel-to-tissue oxygen tension) contribute(s) > 95% to changes in D...

..It is proposed that significant alterations in the enzyme activities may be contributing to decreased metabolism of glutamate, leading to its accumulation...

..g., decreased in energy metabolism) in childhood diseases (e.g., sudden infant death syndrome) in which hypoxia plays a role...

..We conclude that trehalose contributes to anoxia tolerance in flies; this protection is likely to be due to a reduction of protein aggregation...

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