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  • Electronic Resource  (7)
  • human brain  (4)
  • monoamine oxidase  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 8 (1994), S. 171-181 
    ISSN: 1435-1463
    Keywords: Platelet ; monoamine oxidase ; cytochrome oxidase ; isocitrate dehydrogenase ; Down's syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Defects in cytochrome oxidase (CO; complex 4) have recently been demonstrated in blood platelets and in brain tissue from patients with Alzheimer's disease (AD) with possible etiological implications. Because of pathogenetic similarities with AD, we have measured the activities of several mitochondrially localised enzymes in the blood platelets of individuals afflicted with trisomy-21 (Down's syndrome). The activities of monoamine oxidase, cytochrome oxidase, isocitrate dehydrogenase, and glutamate dehydrogenase were assayed in washed platelets from sixty caucasian, male and female control individuals (ages 18–60) and ten, young Down's Syndrome patients (ages 9–21). Significant reductions in the activities of monoamine oxidase, cytochrome oxidase, and isocitrate dehydrogenase were found. In all cases the average activities in Down's syndrome individuals were approximately two-thirds those of controls (DS/Controls=0.68, 0.67, 0.64 respectively). The activity of the fourth enzyme studied, glutamate dehydrogenase, was found to be similar to controls. Results suggest that these reductions are a consequence of a generalised mitochondrial disturbance which may lie behind some pathogenetic aspect(s) of the disease.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1463
    Keywords: Human brain ; age ; monoamine oxidase ; genetic control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of age upon monoamine oxidase -A and -B (MAO-A and -B) in 23 different regions of human brain was determined. There was a significant positive correlation with age in 19 out of 23 regions for MAO-B, but no positive correlation with age was found for MAO-A. The increased MAO-B activity was found, in 5 out of 5 regions tested, to be due entirely to an increased enzyme concentration, rather than due to an increased molecular turnover number of the enzyme. The responses of the mitochondrial marker enzymes succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) were studied in 5 brain regions, and no consistent change in activity found with age. The lysosomal enzyme acid phosphatase was found to tend towards an increased activity with age. No difference in either the specific activities or molecular characteristics of MAO were found between men and women. Cross-correlation studies of the data, after compensation for the effects of age, indicated that the activities of the two enzyme forms are under some form of organized control across the whole brain. Such a finding is consistent with a genetic regulation of the enzyme forms.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1463
    Keywords: Senile dementia of the Alzheimer's type ; vitamin B12 ; methionine adenosyltransferase ; S-adenosylmethionine ; human brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of vitamin B12 on the activity of methionine adenosyltransferase (MAT) in postmortem brains of patients with senile dementia of the Alzheimer's type (SDAT) was investigated. In samples of cortex gyrus frontalis from SDAT patients with normal and low levels of serum B12, MAT Vmax was significantly increased by 25% and 19%, respectively. MAT Vmax from a SDAT group chronically treated with B12 was similar to controls. In contrast to cortex gyrus frontalis, no significant alterations were seen in MAT activity in nucleus caudatus. This study provides evidence that SDAT is associated with significant alterations in transmethylation mechanisms in specific regions of the brain. The relationship between blood levels of B12 and the actual status of this vitamin in the brain influencing the rates of synthesis of both methionine and SAM may, however, be far more complex and cannot be directly clarified on the basis of the present human brain results.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1463
    Keywords: Aminobutyrate aminotransferase ; Alzheimer's disease ; monoamine oxidase ; human brain ; postmortem brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Activities of Gamma-aminobutyrate aminotransferase (GABA-T) and Monoamine oxidase (MAO)-A and-B were estimated in postmortem brains from 6 control subjects without psychiatric or neurologic disorders and 8 histopathologically verified cases of patients with Alzheimer's disease and senile dementia of Alzheimer type (AD/SDAT). The enzyme activities were examined in four cortical brain regions, three nuclei in the basal ganglia, thalamus and white matter. GABA-T activities in the cortical regions (frontal, parietal, occipital and temporal cortices) and nucleus caudatus were significantly lowered in the AD/SDAT patients. The MAO-A activities were significantly increased in the occipital cortex, caudate nucleus, thalamus and white matter in the AD/SDAT patients. No significant differences were found in the other regions (frontal cortex, parietal cortex, temporal cortex, putamen and globus pallidus). The MAO-B activities in three cortical regions (frontal, parietal and occipital cortices), thalamus and white matter were significantly increased in the AD/SDAT patients, whereas no difference was apparent in the other regions. The changed activities could not be correlated with age or postmortem time. The present results are the first describing decreased GABA-T activities as well as increased MAO-A activities in brain from patients with AD/SDAT, while the results with MAO-B support previous findings. A possible connection was found between the order of magnitude of the changes in enzyme activities and the severity of the disease.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1463
    Keywords: Cryosection ; autoradiography ; monoamine oxidase ; brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 11C-labelled L-deprenyl in vitro autoradiography was used to study the regional distribution of MAO-B in human brain. 80 μm thick cryosections from two human brains, a 67 years old female and a 58 years old male, were taken on tape/paper and transferred on to a gelatinized glass plate. The sections were then incubated with 34 and 54 nM11C-L-deprenyl for 15 min and exposed to a film sensitive to high energy radiation for 2 hours. The autoradiograms obtained were analyzed by computerized densiotometry. High11C-deprenyl binding was found in the caudate nucleus, putamen, thalamus, substantia nigra, medial and lateral geniculate bodies, hippocampus and periaqueductal gray. Moderate to low binding was observed in cerebral cortex. Cerebral cortex and white matter showed the lowest binding. The autoradiographic technique described proved to be a fast and reliable method to investigate the topographic localization of MAO-B in large cryosections of human brain.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1463
    Keywords: Keywords: Schizophrenia ; methionine adenosyltransferase ; neuroleptics ; erythrocytes ; human brain ; rat brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. The activity of methionine adenosyltransferase (MAT) was investigated in erythrocytes and postmortem brain specimens (cortex gyrus frontalis, hippocampus and thalamus) of patients with schizophrenia treated with neuroleptics. In comparison with the control group, abnormally low values of MAT Vmax and an increased MAT affinity towards methionine (lower Km values) were found in erythrocytes. In the brain, a regionally selective decrease of MAT Km was found in cortex gyrus frontalis but the Vmax values were however, unchanged. In the regions of cortex gyrus frontalis and hippocampus, but not in thalamus, the values of Vmax and Km were inversely correlated with the duration of schizophrenia. In rats treated for 28 days with the typical neuroleptic haloperidol and the atypical clozapine, a significant increase of MAT activity was found in the corpus striatum. There is the possibility that the changes observed in MAT activity in patients with schizophrenia are attributed to the neuroleptic medication.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 84 (1991), S. 95-102 
    ISSN: 1435-1463
    Keywords: Aminobutyrate aminotransferase ; GABA-T ; human brain ; age factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The activity of 4-aminobutyrate:2-oxoglutarate transaminase (GABA-T) has been investigated in the rat and human brain. Both rat and human brain GABA-T retained its full activity for at least 2 months and with a loss of less than 10% after 6 months when frozen at −20
    Type of Medium: Electronic Resource
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