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  • 1
    Electronic Resource
    Electronic Resource
    Alteration of amino acid metabolism in neuronal aggregate cultures exposed to hypoglycaemic conditions (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 81 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The neuronal effects of glucose deficiency on amino acid metabolism was studied on three-dimensional cultures of rat telencephalon neurones. Transient (6 h) exposure of differentiated cultures to low glucose (0.25 mm instead of 25 mm) caused irreversible damage, as judged by the marked decrease in the activities of two neurone-specific enzymes and lactate dehydrogenase, 1 week after the hypoglycemic insult. Quantification of amino acids and ammonia in the culture media supernatants indicated increased amino acid utilization and ammonia production during glucose-deficiency. Measurement of intracellular amino acids showed decreased levels of alanine, glutamine, glutamate and GABA, while aspartate was increased. Added lactate (11 mm) during glucose deficiency largely prevented the changes in amino acid metabolism and ammonia production, and attenuated irreversible damage. Higher media levels of glutamine (4 mm instead of 0.25 mm) during glucose deprivation prevented the decrease of intracellular glutamate and GABA, while it further increased intracellular aspartate, ammonia production and neuronal damage. Both lactate and glutamine were readily oxidized in these neuronal cultures. The present results suggest that in neurones, glucose deficiency enhances amino acid deamination at the expense of transamination reactions. This results in increased ammonia production and neuronal damage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.00888.x
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural pathology in congenital defects of the urea cycle: Ornithine transcarbamylase and carbamylphosphate synthetase deficiency (1981)
    Springer
    Virchows Archiv 393 (1981), S. 321-331 
    Details
    ISSN: 1432-2307
    Keywords: Urea cycle defects ; OTC deficiency ; CPS deficiency ; Ultrastructural pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Inborn defects of urea synthesis, leading to hyperammonemia, are complex inherited disorders, whose structural sequelae in different tissues and organs have not yet been studied in detail. Ultrastructural investigations have been performed on two cases of deficiencies of two consecutive enzymes of the urea cycle, carbamylphosphate synthetase and ornithine transcarbamylase, and the findings are compared with previously reported results. With regard to liver pathology it appeared that 1). Hepatocytes in CPS deficiency mainly exhibited changes of SER and mitochondrial compartments, whereas 2). OTC deficiency was characterized by regressive liver cell change, with abnormal configuration of the RER, formation of telolysosomes and peribiliary vesiculation. It is suggested that the mitochondrial disorder in the CPS defect is directly related to the lack of a major enzyme protein in this organelle, resulting in structural damage. The leading renal change in CPS deficiency is foot process fusion of glomerular podocytes. Brain alteration in this disorder is similar to that reported for other hyperammonaemic urea cycle defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430832
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Liver pathology in a new congenital disorder of urea synthesis: N-acetylglutamate synthetase deficiency (1985)
    Springer
    Virchows Archiv 408 (1985), S. 259-268 
    Details
    ISSN: 1432-2307
    Keywords: Urea cycle defects ; N-acetylglutamate synthetase deficiency ; Liver pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Detoxification through the urea cycle is the means by which mammalian organisms dispose of their excess ammonia. Within this cycle, N-acetylglutamate (NAG) is the most important cofactor for optimal enzyme activity. It is formed from acetyl CoA and glutamate through the action of N-acetylglutamate synthetase (NAGS). Recently, a congenital deficiency of NAGS has been reported. In this communication, we present results of structural investigations on liver tissue of the index patient with NAGS defect. Light microscopy revealed small, eosinophilic inclusions in some of the hepatocytes. Electron microscopy showed vesicular SER and fibrillar material in expanded cisterns of the RER, presumably corresponding to the inclusions seen in light microscopy. Immunofluorescence of liver tissue uncovered a discrete distribution of intracellular albumin in the form of small deposits. We suggest that in NAGS deficiency, some secretory proteins might be incompletely processed due to the lack of a protease activator, NAG.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707988
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  • 4
    Electronic Resource
    Electronic Resource
    Liver pathology in transient neonatal hyperammonemia (1983)
    Springer
    Virchows Archiv 402 (1983), S. 25-33 
    Details
    ISSN: 1432-2307
    Keywords: Urea cycle defects ; Transient neonatal hyperammonaemia ; Ultrastructural pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultrastructural investigations have been performed on two cases of transient neonatal hyperammonaemia (TNH). This newly recognized metabolic disorder is chiefly characterized by severe hyperammonaemia in the postnatal period, a comatous state, absence of abnormal organic aciduria, normal activity of urea cycle enzymes and, usually, complete recovery. The aetiology is presently unknown. Electron microscopy uncovered rather congruent alterations of hepatocyte structure, with a wide spectrum of mitochondrial lesions, an increase of autophagous bodies with organelle remnants, and changes in the excretory apparatus. Thus, in contrast to some of the hereditary disorders of the urea cycle, no specific structural changes could be found in TNH. This finding is in line with the observation of normal activities of main urea enzymes in these cases, and indicates that a different biochemical system may be pathogenetically involved in TNH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695046
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    Paper (German National Licenses)
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