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Biomedical subjects

B Guibert

Publications and source records attributed to B Guibert.

86 records · Page 5Linked to original sources
PubMed1983

Effects of naloxone on dopamine release in the nigrostriatal system.

Simultaneously with a systemic injection of naloxone (NAL), the effects of the nigral application of the d(+)-amphetamine (AMPH) or of right forepaw stimulation on the release of [3H]dopamine [( 3H]DA) in the two caudate nuclei (CN) and the two substantia nigrae (SN) were examined in halothane-anesthetized cats. These experiments were carried out using four push-pull cannulae implanted bilaterally in the CN and SN and continuously supplied with [3H]tyrosine [( 3H]Tyr), the metabolic precursor of dopamine. Nigral AMPH application (1 muM) produced a local increase of the [3H]DA in spite of the NAL injection (5 mg/kg) but the presence of this drug prevented the expected effect of AMPH in the three other structures. Furthermore, the effects of electrical forepaw stimulation (EPS) were abolished by injection of NAL. NAL alone had no effect on the spontaneous release of [3H]DA. It is concluded that antagonism between NAL and AMPH could be due: (1) to enkephalinergic control of dopamine regulated nigral efferents, (2) to an action on the thalamic structures responsible for the reciprocal control of the two nigrostriatal dopaminergic pathways.

Animals↗
PubMed1983

Release of adenosine in vivo from cat caudate nucleus.

A push-pull perfusion technique was used to study the release of endogenously synthesized [3H]-adenosine from caudate nucleus in the anaesthetized cat. The spontaneous release of [3H]adenosine newly synthesized from [3H]adenine reached a steady state level 40 min after the beginning of superfusion and continued for 4 h. Potassium and veratridine increased the release of newly synthetized [3H]-adenosine. The action of veratridine was completely blocked by tetrodotoxin. We conclude that spontaneous and evoked release of adenosine occurs in the cat striatum and might potentially affect central nervous function.

Adenosine↗
PubMed1983

[11C-Ro15-1788 and 11C-flunitrazepam, two coordinates for the study by positron emission tomography of benzodiazepine binding sites].

In vivo binding of a benzodiazepine (flunitrazepam-C11) and a benzodiazepine antagonist (Ro 15-1788-C11) were studied with positron emission tomography. Advantages and disadvantages of each drug for studying specific in vivo binding sites are presented. The results obtained indicate that Ro 15-1788-C11 is a better in vivo radiocoordinat than flunitrazepam-C11.

Animals↗
PubMed1983

[In vivo study of benzodiazepine receptors using positron emission tomography].

The results obtained by positron-emission tomography in an "in vivo" study on the baboon using a benzodiazepine (flunitrazepam) labeled with carbon-11 are presented. The specificity of "in vivo" binding of Flunitrazepam-11C was demonstrated by competition with Lorazepam in the brain, but it was not possible to verify the criterium of stereospecificity "in vivo". The preliminary results of a study carried out under the same conditions on RO 15 1788 11C show the interest of using this labeled antagonist as an "in vivo" ligand for the specific binding sites of benzodiazepines in positron-emission tomography.

Animals↗
PubMedDate not supplied

Granulocyte-macrophage colony stimulating factors (GM-CSF) and interleukin 8 (IL-8) production by human bronchial epithelial cells (HBEC) in asthmatics and controls. Lack of in vitro effect of salbutamol compared to sodium nedocromil.

The bronchial epithelium produces cytokines that could contribute to inflammatory events in airways. In this study we determined the basal and TNFalpha stimulated productions of GM-CSF and IL-8 by human bronchial epithelial cells (HBEC) collected from 12 control and six asthmatic patients. Spontaneous and TNFalpha-induced GM-CSF or IL-8 released levels increased significantly with time. Epithelial cells from asthmatic patients spontaneously released high levels of GM-CSF (24 h). TNFalpha potentiated GM-CSF and IL-8 release in control subjects and only the IL-8 production in asthmatics. Nedocromil sodium, an antiinflammatory drug, and salbutamol, a beta2-agonist, are commonly used in asthma. They were evaluated on the spontaneous and TNF-induced expression of GM-CSF and IL-8 in cultured bronchial epithelial cells. Nedocromil sodium, at the concentration of 10(-6) M, reduced the TNF-induced increase in GM-CSF but not the IL-8 release. Salbutamol, at the concentration of 10(-6) or 10(-5) M, did not affect the constitutive or stimulated production of both cytokines.

Adrenergic beta-Agonists↗
PubMedDate not supplied

Relationships between benzodiazepine receptors, impairment of GABAergic transmission and convulsant activity of beta-CCM: a PET study in the baboon Papio papio.

Central type benzodiazepine receptors were studied in vivo by positron emission tomography in brain areas of 2 different groups of the baboon Papio papio: non-photosensitive (group 1) and those with an allylglycine-induced decrease in GABA-mediated inhibition (group 2). Further, a naturally photosensitive Papio papio (+3 level of photosensitive response) was compared to both groups. Regional brain binding of the specific benzodiazepine receptor ligand, [11C]Ro 15-1788, was not significantly different between groups 1 and 2. In addition, the data from the naturally photosensitive Papio papio did not seem to differ markedly from groups 1 and 2 either. Pharmacological effects of increasing doses of beta-CCM (0.05-3 mg/kg i.v.) and regional benzodiazepine receptor occupancy by the drug were simultaneously studied using electroencephalographic activity recording and positron emission tomography. A positive correlation was observed between the degree of photosensitivity of the baboon and sensitivity to the action of beta-CCM, with increasing convulsant efficacy of beta-CCM in going from group 1 to the naturally photosensitive baboon, then to group 2. Dose-related displacement curves of [11C]Ro 15-1788 binding by beta-CCM revealed that reduction in brain GABA concentration did not modify the inhibitory potency of beta-CCM on [11C]Ro 15-1788 binding in cerebral cortex. This suggests a lack of detectable in vivo allosteric effects of GABA on beta-CCM binding during beta-CCM-induced seizures. Thus, a given dose of beta-CCM displayed increasing pharmacological potency in going from baboons with the lowest photosensitivity to those with the highest, whereas benzodiazepine receptor occupancy by beta-CCM was similar in the cerebral cortex of the different baboons. Conversely, a given level of convulsant activity of beta-CCM was related to a different benzodiazepine receptor occupancy by the drug, depending on the photosensitivity of Papio papio. A given dose of a drug may, thus, have a different pharmacological potency when occupying the same number of receptors, depending on the physiopathological state of the subject.

Animals↗
PubMedDate not supplied

A new device for the treatment of pleural malignancies: intrapleural chemohyperthermia preliminary report.

The prognosis of malignant pleural tumors remains extremely unfavorable. The aim of this study is to evaluate the combination of intrathoracic intrapleural chemotherapy and intrapleural hyperthermia (ITCH) in these diseases. Under anesthesia, 5 men were studied. After pleurectomy for mesothelioma (3/5) or adenocarcinoma (2/5), ITCH is carried out for over 60 min, either with mitomycin C (4/5) or cisplatin (1/5). No pre- or postoperative death occurred. The maximal pleural temperature is 42.6 degrees C. The blood level of mitomycin C never reached the systemic toxic level. All the patients were discharged from the surgical ward, 3 are still alive 15 months later. Therefore, ITCH appears to be a safe and reliable therapy.

Adenocarcinoma↗
PubMedDate not supplied

[Cytological diagnosis of prostatic cancer by transrectal aspiration biopsy (author's transl)].

From the cytologic study of fifty transrectal needle aspirations of the prostate the authors try to establish the principles leading to the diagnosis of prostatic carcinoma. Correlation with clinical diagnosis shows that in positive cases, cytologic diagnosis is accurate. In the case of negative cytologic responses this negative response may be imputable: to the paucicellularity of the sample, unavoidable blind needle aspiration, an early necrosis of the cellular material, a false interpretation of minimal cellular and nuclear abnormalities. This method proves valuable for the clinician. In two cases out of three the cytological diagnosis confirms the clinical diagnosis.

Biopsy, Needle↗