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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A direct involvement of the antioxidant enzyme NAD(P)H:quinone oxidoreductase (NQO1) in neuroprotection has not yet been shown. The aim of this study was to examine changes, localization and role of NQO1 after different neuronal injury paradigms. In primary cultures of rat cortex the activity of NQO1 was measured after treatment with ethylcholine aziridinium (AF64A; 40 µm), inducing mainly apoptotic cell death, or oxygen-glucose deprivation (OGD; 120 min), which combines features of apoptotic and necrotic cell death. After treatment with AF64A a significant NQO1 activation started after 24 h. Sixty minutes after OGD a significant early induction of the enzyme was observed, followed by a second increase 24 h later. Enzyme activity was preferentially localized in glial cells in control and injured cultures, however, expression also occurred in injured neuronal cells. Inhibition of the NQO1 activity by dicoumarol, cibacron blue or chrysin (1–100 nm) protected the cells both after exposure to AF64A or OGD as assessed by the decreased release of lactate dehydrogenase. Comparable results were obtained in vivo using a mouse model of focal cerebral ischaemia. Dicoumarol treatment (30 nmol intracerebroventricular) reduced the infarct volume by 29% (p = 0.005) 48 h after the insult. After chemical induction of NQO1 activity by t-butylhydroquinone in vitro neuronal damage was exaggerated. Our data suggest that the activity of NQO1 is a deteriorating rather than a protective factor in neuronal cell death.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The question whether during the process of cholinergic degeneration somatostatin- and/or neuropeptide Y-containing neurons in rat hippocampus and cortex react to the withdrawal of cholinergic function was addressed. After bilateral intracerebroventricular injection of the cholinotoxin ethylcholine aziridinium (AF64A; 1 or 2 nmol/ventricle) in rats, the activity of choline acetyltransferase (ChAT) started to decline in the hippocampus within 24 h. The reduction of ChAT activity reached its maximum within 4 days (34 and 55% after 1 and 2 nmol of AF64A/ventricle, respectively) and persisted during the observation period of 14 days. In the parietal cortex, ChAT activity decreased by 23% 4 days after 2 nmol of AF64A/ventricle. The loss in ChAT activity was accompanied by a transient decline in the levels of somatostatin and a transient increase in the levels of neuropeptide Y in both brain areas. In the hippocampus, the reduction in somatostatin content was most pronounced after 2 days (by 22 and 33% after 1 and 2 nmol of AF64A/ventricle, respectively). Within 14 days, somatostatin levels returned to control values. Neuropeptide Y levels increased slightly by ∼25% of control values in the hippocampus. The changes described were present in both the dorsal and ventral subfields of the hippocampus. Similar but less pronounced changes in levels of both neuropeptides were observed in the parietal cortex. The present data provide further evidence for a close neuronal interrelationship between cholinergic and somatostatin- and/or neuropeptide Y-containing neurons in rat hippocampus and parietal cortex.
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Intracerebroventricular injection of ethylcholine aziridinium (AF64A) (2 nmol/ventricle) induced a considerable decrease in the level of acetylcholine (ACh) in hippocampus (from 21.14 ± 0.84 to 10.04 ± 0.59 pmol/mg of tissue; p 〈 0.001) 4 days after application. The reduction of cholinergic function was accompanied by a decrease in the level of noradrenaline (NA) (from 1.96 ± 0.08 to 1.41 ± 0.06 pmol/mg of tissue; p 〈 0.001). Two days after administration of AF64A (1 or 2 nmol/ventricle), the dose-dependent decrease in NA level was associated with an increase in the level of its major metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), resulting in a considerable increase in the MHPG/ NA molar ratio (from 0.84 ± 0.06 to 1.62 ± 0.17; p 〈 0.002). Chronic treatment of AF64A-injected rats with clonidine (0.02–0.2 mg/kg, i.p., every 8–12 h) had no significant effect on the loss of ACh content, whereas the decrease in NA content in hippocampus was completely prevented. Clonidine induced aggressive behavior in the AF64A-treated rats, in contrast to sedation in vehicle-injected rats. The response to clonidine under these experimental conditions and the increased MHPG/NA molar ratio in response to AF64A suggest that the transient loss of NA content following AF64A administration results from increased NA release. The increased noradrenergic activity in hippocampus may be linked to the reduction of tonic inhibitory cholinergic input. These results are discussed in relation to possible implications for senile dementia of the Alzheimer type.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The mRNA levels of secretogranin II, chromo-granin B, and VGF were compared in brains of control and AF64A-treated rats. This toxin induces specific lesions of the septohippocampal cholinergic pathway. As a consequence of this treatment, the Chromogranin B message was elevated in the dentate gyrus granule cells of the hippocampus. In the paraventricular nucleus of the hypothalamus, a concomitant elevation of the messages of secretogranin II and corticotropin-releasing factor occurred in the parvocellular neurons, and an increase of those of secretogranin II and VGF occurred in a subgroup of magnocellular neurons. Further increases for secretogranin II were seen in the amygdaloid nuclei and the reticular thalamic nuclei and increases for Chromogranin B in the temporal cortex, substantia nigra compacta, and ventral tegmental area. These results indicate that the toxin-induced lesion of the cholinergic pathway innervating the hippocampus apparently leads to the stimulation of several defined groups of neurons that react with an increase in the mRNA levels of their secretory peptides. We suggest that changes in mRNA expression of these peptides are useful parameters for defining neurons under chronic stimulation. Key Words: Secretory peptides—Large dense core vesicles—Corticotropin releasing factor—Septohippocampal cholinergic system—Hippocampus—AF64A.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 37 (1981), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: There is evidence that histamine may be a neurotransmitter in mammalian brain. Histamine in neurons of the central nervous system is easily released and rapidly turned over. The cellular localization of histamine-N-methyltransferase, the proposed histamine-inactivating enzyme, was investigated by measuring its activity in rat striatum after applying neurochemical or electrolytic lesions. The results indicate a major neuronal localization of the enzyme in this area.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 20 (1973), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Rabbits were immunized with chromomembrin B, i.e. a membrane protein isolated from chromaffin granules of bovine adrenal medulla. When the rabbit sera were tested by immunodiffusion in the presence of various detergents, only negative results were obtained, whereas with complement fixation antibodies could be demonstrated. With this method the subcellular distribution of chromomembrin B in bovine adrenal medulla was determined. The results demonstrate that this protein is specifically localized in the membranes of chromaffin granules. In the mitochondrial and microsomal fractions it is present only in small amounts which are attributable to a contamination of these fractions with chromaffin granules. The subcellular distribution of chromomembrin R in bovine splenic nerves indicates that this antigen is also found in the membranes of noradrenalinestoring vesicles of sympathetic nerve. Chromomembrin B or a related antigen was detected in chromaffin grades isolated from pig and rat adrenal and in those isolated from a human phaeochromocytoma. It is also present in total membranes obtained from posterior and anterior hypophysis, but it is absent from membranes isolated from parotid gland, liver and adrenal cortex. This paper illustrates how a membrane protein which requires detergents for its solubilization can be characterized and measured by immunological methods.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 35 (1980), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A new assay procedure for dopamine β-hydroxylase (DBH) in tissue extracts is described. Solubilized DBH was adsorbed from crude extracts on Concanavalin A-Sepharose (Con A-Sepharose), resulting in enrichment of the enzyme as well as removal of endogenous catecholamines and inhibitory substances. The enzymatic assay was carried out with DBH still adsorbed to Con A-Sepharose. The adsorption of the DBH to Con A-Sepharose offers three advantages over previous assay procedures. (1) Because of removal of the endogenous inhibitory substances, a single Cu2+ concentration can be used for the determination of DBH activity, regardless of the tissue dilution or inhibitor content of the analysed sample. Using this procedure, the optimal Cu2+ concentration for DBH of bovine adrenal gland extracts was 3 μM and for rat brain 10 μM. (2) Because of removal of endogenous catecholamines, dopamine, the main physiological substrate of DBH in noradrenergic neurons, can be used for the assay. The enzymatic reaction product, noradrenaline, was determined by high performance liquid chromatography and electrochemical detection (hplc-ec). This procedure resulted in an approx. 10-fold increase in sensitivity of the assay compared with other procedures, e.g., the radioenzymatic assay. (3) Direct determination of the immediate product of the enzymatic reaction (noradrenaline) permits kinetic analysis. It was found that the Michaelis constants for the substrate (dopamine) and co-factor (ascorbic acid) (2 mM and 0.65 mM, respectively) determined in bovine adrenal tissue extracts by the described procedure were identical with the values for the purified DBH preparation.
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Statins [3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors] exert cholesterol-independent pleiotropic effects that include anti-thrombotic, anti-inflammatory, and anti-oxidative properties. Here, we examined direct protective effects of atorvastatin on neurones in different cell damage models in vitro. Primary cortical neurones were pre-treated with atorvastatin and then exposed to (i) glutamate, (ii) oxygen–glucose deprivation or (iii) several apoptosis-inducing compounds. Atorvastatin significantly protected from glutamate-induced excitotoxicity as evidenced by propidium iodide staining, nuclear morphology, release of lactate dehydrogenase, and mitochondrial tetrazolium metabolism, but not from oxygen–glucose deprivation or apoptotic cell death. This anti-excitototoxic effect was evident with 2–4 days pre-treatment but not with daily administration or shorter-term pre-treatment. The protective properties occurred independently of 3-hydroxy-3-methylglutaryl-CoA reductase inhibition because co-treatment with mevalonate or other isoprenoids did not reverse or attenuate neuroprotection. Atorvastatin attenuated the glutamate-induced increase of intracellular calcium, which was associated with a modulation of NMDA receptor function. Taken together, atorvastatin exerts specific anti-excitotoxic effects independent of 3-hydroxy-3-methylglutaryl-CoA reductase inhibition, which has potential therapeutic implications.
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  • 9
    ISSN: 1432-0584
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurde die subzelluläre Verteilung zweier Esterasen in neutrophilen Granulozyten von Patienten mit chronischer Myelose bestimmt. Eine der beiden Esterasen hydrolysierte den N-Acetyl-L-Tyrosinäthylester, der ein typisches Substrat für Chymotrypsin ist, die andere hydrolysierte Naphthol-AS-D-chloracetat, das in der Zytochemie zur Darstellung von Esteraseaktivitäten verwendet wird. Beide Esteraseaktivitäten konnten in der Granulafraktion lokalisiert werden, das pH-Optimum ihrer Aktivität liegt bei pH 7,4. 59% der gesamten Granulaproteine konnten in 0,15M NaCl (pH 7,0) gelöst werden. Die löslichen Granulaproteine enthielten 73% der Naphthol-AS-D-chloracetat-Esteraseaktivität, jedoch nur 17% der Esteraseaktivität gegenüber dem N-Acetyl-L-Tyrosinäthylester. Die Acrylamid-Gelelektrophorese bei pH 4,3 zeigte mehrere Banden mit Esteraseaktivität gegenüber Naphthol-AS-D-chloracetat. Zum Vergleich des Proteinmusters des löslichen Lysats mit dem des unlöslichen Rückstands der Granulafraktion wurde nach dem Lösen der Proteine in einer Mischung aus Phenol, Eisessig und Harnstoff eine weitere Acrylamid-Gelelektrophorese durchgeführt. Die Hydrolyse des Naphthol-AS-D-chloracetats durch die Granulafraktion wurde mit der Spaltung des gleichen Substrats durch die Proteasen Chymotrypsin, Trypsin und Pankreatopeptidase E (Elastase) verglichen.
    Notes: Summary The subcellular distribution has been investigated of two esterases from human neutrophil granulocytes obtained from patients with chronic myelocytic leukemia. One esterase hydrolyzed the typical chymotrypsin substrate N-acetyl-L-tyrosine ethyl ester, the other hydrolyzed naphthol AS-D chloroacetate, a substance which is used in cytochemistry for the demonstration of esterase activity. Both enzymes could be recovered almost exclusively in the granule fraction and were optimally active at about pH 7.4. After lysis of the granules by hypoosmotic shock 73% of the naphthol AS-D chloroacetate esterase activity could be dissolved in buffered 0.15M sodium chloride (pH 7.0) in contrast to only 17% of the N-acetyl-L-tyrosine ethyl esterase activity. The soluble lysate contained 59% of the total granule protein. It was subjected to acrylamide-gel electrophoresis at acid pH and multiple bands of naphthol AS-D chloroacetate esterase activity were demonstrated on the gels. Acrylamide-gel electrophoresis of the insoluble proteins and the soluble lysate of the granule fraction was carried out after dissolution of the proteins in phenol-acetic acid-urea and the resulting electrophoretic patterns were compared. Hydrolysis of naphthol AS-D chloroacetate by the granule fraction was compared to hydrolysis of the same substrate effected by the pure proteases chymotrypsin, trypsin, and pancreatopeptidase E.
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  • 10
    ISSN: 1432-0584
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Lösliche Proteine einer Granulafraktion aus menschlichen Neutrophilen wurden einer Acrylamidgel-Elektrophorese (15% Acrylamidgel bei pH 4,3) unterwerfen. Verschiedene Proteinbanden zeigten eine hydrolytische Aktivität gegenü ber Naphthol-AS-D-Chloracetat bei pH 7,4. Die elektrophoretische Wanderung der Naphthol-AS-D-Chloracetat spaltenden Esterase ist ähnlich der von Trypsin, Chymotrypsin und Elastase.
    Notes: Summary Soluble proteins of a granule fraction derived from human neutrophils were subjected to electrophoresis on 15% acrylamide gels at pH 4.3 Several of the protein bands were shown to possess hydrolytic activity on naphthol AS-D chloroacetate at pH 7.4. Electrophoretic movement of NASDCA esterases is similar to those of trypsin, chymotrypsin and elastase.
    Type of Medium: Electronic Resource
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