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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 60 (1993), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The specific binding of L-[3H]glutamate to its receptors was investigated on crude membrane preparations from different brain regions of pentylenetetrazole-kindled rats using a binding assay technique. Pentylenetetrazole kindling induced by 10 intraperitoneal applications of 45 mg/kg over a period of 20 days resulted in a significant increase of both the convulsive susceptibility of animals to the convulsant and the specific L-[3H]glutamate binding in hippocampus and in motor, frontal, and inferiotemporal (acoustic) cortex tested with a L-[3H]glutamate concentration of 50 nM. No differences were observed in the other brain structures studied. Kinetic studies indicated that the enhanced L-[3H]glutamate binding to hippocampal membranes from kindled rats reflects changes in the density of the glutamate binding sites rather than an increase in receptor affinity. To study the effect of acute generalized convulsions on L-[3H]glutamate binding to synaptosomal membranes of hippocampus and visual cortex, rats were treated 24 h before the experiment with 60 mg/kg of pentylenetetrazole, i.p. Under these conditions, no differences between treated and control rats were observed. From these findings, it is concluded that the increase in glutamate receptor density demonstrated in hippocampus and several neocortical brain structures of pentylenetetrazole-kindled rats may be the expression of a specific enhancement of susceptibility of glutamatergic systems to this excitatory amino acid developing in the course of formation of pentylenetetrazole-induced kindling.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 6 (1994), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Endogenous opioid peptides modulate and regulate processes of central excitability. Furthermore, opioids are thought to interfere with processes of learning and memory storage. In order to study the effects of endogenous opioids on both processes we injected in the course of development of pentylenetetrazol kindling the opiate receptor antagonist naloxone, and tested the animals afterwards in a shuttle-box task. It was found that naloxone pretreatment had dissociative effects. There was no effect on seizure outcome, whereas the learning deficit was ameliorated in the kindled group. The data suggest that endogenous opioid peptides contribute to the learning deficit found in pentylenetetrazol-kindled rats.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1437-2320
    Keywords: Glioblastoma ; positron emission tomography (PET) ; regional cerebral blood flow ; single photon emission computer tomography (SPECT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 99mTc-hexamethyl-propyleneamine-oxime (HM-PAO) was developed as a radiotracer of regional cerebral blood flow (rCBF) with SPECT. THe purpose of this study was to investigate if HM-PAO is able to trace rCBF in primary brain tumors. In 10 patients with glioblastoma grade IV the intracerebral distribution of HM-PAO was studied in comparison with C15O2 steady state inhalation technique and PET for rCBF evaluation. In all instances the cerebral HMPAO distribution was comparable with rCBF pattern as confirmed by a significant correlation of tumor to cortex ratios. The results indicate the clinical usefulness of HMPAO for tracing rCBF in brain tumors.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 349 (1994), S. 492-496 
    ISSN: 1432-1912
    Keywords: Kindling ; Pentylenetetrazol ; Learning ; Diazepam ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Repeated administration of pentylenetetrazol (PTZ) induces kindling and impairs shuttle-box learning. The available literature suggesting a close connection between seizure frequency and mental deficits in human epileptics allows us to hypothesize that seizure inhibition prevents the progressive mental retardation associated with kindling. In order to investigate the effect of motor seizure inhibition on mental impairment we administered diazepam (DZP) doses of 0.5 and 2.5 mg/kg, respectively 60 min prior to the 10 convulsant injections. After completion of kindling the learning performance of the rats was tested in the shuttle-box. PTZ kindling resulted in diminished shuttle-box learning. In control rats treated with DZP no significant changes in their learning ability occurred. Although DZP was found to suppress kindling development effectively a worsened shuttle-box learning could be observed in all PTZ groups treated with DZP.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1106
    Keywords: Key words Chemical kindling ; Glutamate binding sites ; NMDA ; mGluR ; Inositol triphosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Kindling induced by 13 intraperitoneal injections of 40 mg/kg pentylenetetrazole (PTZ) over a period of 4 weeks resulted in a significant long-lasting increase in both the convulsive susceptibility of animals to the convulsant and the density of the specific [3H]-l-glutamate binding sites in the hippocampus. The quisqualate- and kainate-sensitive [3H]-l-glutamate binding sites were increased 24 h after the final PTZ injection, whereas the N-methyl-d-aspartate (NMDA)-sensitive sites had only a tendency to be enhanced. Furthermore, we investigated [3H]-l-glutamate binding on metabotropic receptors and found a significant increase in the hippocampus following PTZ kindling. In addition, in hippocampal tissue of kindled rats (±)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD)-stimulated inositol phosphate formation is increased. It can be concluded that the increase in metabotropic glutamate receptor (mGluR) density may be the expression of a specific enhancement in susceptibility of the glutamatergic systems to this excitatory amino acid developing in the course of PTZ-induced kindling.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 349 (1994), S. 492-496 
    ISSN: 1432-1912
    Keywords: Key words: Kindling – Pentylenetetrazol – Learning – Diazepam – Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Repeated administration of pentylenetetrazol (PTZ) induces kindling and impairs shuttle-box learning. The available literature suggesting a close connection between seizure frequency and mental deficits in human epileptics allows us to hypothesize that seizure inhibition prevents the progressive mental retardation associated with kindling. In order to investigate the effect of motor seizure inhibition on mental impairment we administered diazepam (DZP) doses of 0.5 and 2.5 mg/kg, respectively 60 min prior to the 10 convulsant injections. After completion of kindling the learning performance of the rats was tested in the shuttle-box. PTZ kindling resulted in diminished shuttle-box learning. In control rats treated with DZP no significant changes in their learning ability occurred. Although DZP was found to suppress kindling development effectively a worsened shuttle-box learning could be observed in all PTZ groups treated with DZP.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 13 (1988), S. 648-652 
    ISSN: 1619-7089
    Keywords: Positron-emission tomography (PET) ; Myocardial perfusion ; Myocardial metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Positron-emission tomography (PET) and radioactively labelled substrates permit metabolic studies to be carried out in vivo and in situ with few if any limitations regarding the choice of substrates as long as they can be tagged with positron-emitting radionuclides, especially those like 11C and 13N. With respect to cardiology, 13N-ammonia and 82Rb are helpful in the examination of myocardial perfusion. The evaluation of myocardial glucose and fatty acid metabolism with 18F-deoxyglucose (FDG) and 11C-palmitate has proved to be clinically useful. Thus, myocardial ischemia and hypoxia, infarct size, the transmural extent of the infarction and tissue viability after it can all be examined as can pathological biochemistry in patients with primary or secondary cardiomyopathies. Single-photon-emitting labelled substances such as 123I-labelled fatty acid analogues also provide information equivalent to that which can be gathered by PET for clinical use. Thus, one major task of PET is the validation of methods and the transformation of these methods to single-photon-emitting radiotracers for broad clinical application, in situations where the expense of PET cannot at present be justified.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1439-099X
    Keywords: Schlüsselwörter: p53-Überexpression ; Hypoxie ; Kopf-Hals-Karzinome ; Key Words: p53 ; Hypoxia ; Head and neck carcinomas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Purpose: Clinical investigation of a potential relationship between the polarographically measured tumor oxygenation and the p53 status in patients with squamous cell carcinoma of the head and neck. Patients and Methods: In 99 patients with mostly advanced, histologically proven squamous cell carcinoma of the head and neck were estimated the classical tumor parameters (TNM stage, histological grading) the immunohistochemical p53-overexpression (DO-7) and the tumor oxygenation status (Eppendorf pO2 Histograph). The tumor volume and the hemoglobin concentration were evaluated simultaneously. Results: No statistically significant difference could be detected between immunohistological p53-positive (p53 ≥ 10% stained cells) and p53-negative tumors (p53 〈 10% stained cells) regarding both the median pO2 and the relative frequency of values ≤ 5 mm Hg. Moreover, no statistically relevant differences could be seen between both p53-groups considering the hemoglobin concentration, the TNM stag, the histological grading and the tumor volume. Conclusion: Our data imply that there is no association between p53-overexpression and tumor hypoxia in head and neck carcinomas. However, this is not necessarily in contradiction to experimental or clinical data that confirmed a relationship between hypoxia and p53-mediated increased malignancy of tumor cells in other tumor entities. The comparable oxygenation status of p53-positive and p53-negative tumors in our study is associated with an analogous clinical tumor aggressiveness of both groups. That could be caused by hypoxia related but p53-independent selection of tumor cells with a more malignant phenotype in head and neck carcinomas. However, further research is needed to prove this possible relationship.
    Notes: Ziel: Klinische Prüfung einer potentiellen Beziehung zwischen polarographisch gemesener Tumoroxygenierung und p53-Status bei Patienten mit Plattenepithelkarzinomen der Kopf-Hals-Region. Patienten und Methode: Bei 99 Patienten mit überwiegend fortgeschrittenen, histologisch gesicherten Plattenepithelkarzinomen der Kopf-Hals-Region wurden neben den klassischen Tumorparametern (TNM-Stadium, histologisches Grading) die immunhistochemische p53-Überexpression (DO-7) und der Tumoroxygenierungsstatus ermittelt (Eppendorf-pO2-Histograph). Simultan erfolgte die Bestimmung des Tumorvolumens und der Hämoglobinkonzentration. Ergebnisse: Zwischen immunhistochemisch p53-positiven (≥ 10% angefärbte Zellen) und p53-negativen (〈 10% angefärbte Zellen) Tumoren fand sich weder für den pO2-Median noch für die relative Anzahl von Werten ≤ 5 mm Hg ein statistisch signifikanter Unterschied. Auch bei der Betrachtung der Hämoglobinkonzentration, der TNM-Klassifikation, des histologischen Gradings und des Tumorvolumens fanden sich zwischen beiden p53-Gruppen keine statistisch relevanten Differenzen. Schlussfolgerung: Unsere Daten sprechen gegen eine Assoziation von p53-Überexpression und Tumorhypoxie bei Kopf-Hals-Karzinomen. Zu experimentellen und klinischen Ergebnissen, die bei anderen Tumorentitäten zeigen, dass Hypoxie zu einer p53-vermittelten Steigerung der Malignität führt, ergibt sich trotzdem kein prinzipieller Widerspruch. Die in unserer Studie adäquate Oxygenierung von p53-positiven und p53-negativen Tumoren reflektiert sich in einer vergleichbaren klinischen Tumoraggressivität beider Gruppen. Dies könnte dadurch bedingt sein, dass bei Kopf-Hals-Karzinomen hypoxieassoziierte, aber p53-unabhängiger Formen der Selektion von Tumorzellen mit malignerem Phänotyp zum Tragen kommen. Es bedarf jedoch weiterführender Untersuchungen, um einen solchen möglichen Zusammenhang zu belegen.
    Type of Medium: Electronic Resource
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