Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:6.3.4.6 (
urease
)
7,490
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Using in vivo 1H NMR spectroscopy (1H MRS) and biochemical analysis, the effects of hyperammonemia on cerebral function were studied in three rat models: acute liver ischemia (LIS), administration of
urease
(UREASE) and administration of methionine sulfoximine (MSO). By means of localization in three dimensions signals were obtained exclusively from the cerebral cortex. Specially developed lineshape correction and fitting methods were used to quantitate the MRS signals. The following concentration changes were observed; a decrease in glutamate and (phospho)choline for all the models; an increase in glutamine in the LIS and UREASE model but a decrease in the MSO model; a marked increase in lactate in the LIS and UREASE group; a tendency to a decrease in
N-acetylaspartate
in all the models. These changes agree well with the changes in the post-mortem biochemically determined cerebral cortex glutamine and glutamate concentrations. Estimated absolute 1H MRS metabolite concentrations agree well with those obtained by other techniques; cerebral cortex glutamate, however, is underestimated by about 35% by NMR. The present data support the hypothesis that hyperammonemia is associated with a decreased availability of glutamate for neurotransmission.
...
PMID:The use of in vivo proton NMR to study the effects of hyperammonemia in the rat cerebral cortex. 167 7
The use of a rapid and sensitive assay for
N-acetylaspartate
(
NAA
) in urine or eluates from dried urine on filter paper to make a chemical diagnosis of Canavan disease (CD) is described. It involves a simplified
urease
pretreatment for sample preparation and gas chromatography-mass spectrometry (EI, scanning mode) with or without stable isotope dilution. Significant improvements in the recovery of
NAA
and the GC-MS data-handling device made the assay without stable isotope dilution sensitive and quantitative enough to diagnose CD: Its coefficient of variation (CV) was below 12%. The CV obtained with stable isotope dilution was below 9%. One patient with CD had an abnormal
NAA
level that was more than 6 S.D. above the mean of the age-matched controls. This diagnostic procedure is accurate for screening and for the chemical diagnosis of CD, with a good cost:benefit ratio. The urinary
NAA
levels of the healthy controls decreased significantly with age. This change should be considered in making a chemical diagnosis of this disease.
...
PMID:Rapid and sensitive screening for and chemical diagnosis of Canavan disease by gas chromatography-mass spectrometry. 1514 8
