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Biomedical subjects

C Tranchant

Publications and source records attributed to C Tranchant.

100 records · Page 6Linked to original sources
PubMed1988

Effects of drugs affecting dopaminergic neurotransmission in rats with spontaneous petit mal-like seizures.

Drugs interacting with dopaminergic neurotransmission were studied on a model of genetic petit mal-like seizures in a strain of Wistar rats. Dopamine participates in the control of seizures in this model, as in other models of petit mal or of genetic epilepsy. Mixed dopaminergic D1/D2 agonists: L-DOPA, apomorphine, amphetamine and nomifensine, gave dose-dependent reductions of the duration of spike and wave discharges. Mixed D1/D2 antagonists: haloperidol, flupentixol and pimozide, caused dose-dependent increases of duration of spike and wave discharges. The findings with specific agonists or antagonists of D1 or D2 receptors did not reveal clearly the respective roles of these receptors in controlling the spike and wave discharges. The D2 agonists, lisuride and pergolide, had no effect on spike and wave discharges, except at toxic doses; bromocriptine decreased the duration of the discharges, but without clear-cut dose-dependency. The D2 antagonists: sulpiride and tiapride, had no effect. The D1 agonist SKF 38393 decreased duration of the spike and wave discharges in a dose-dependent manner. The D1 antagonist SCH 23390 had a biphasic effect: increasing the duration of spike and wave discharges at small doses and decreasing it at large doses. These results suggest that the simultaneous stimulation or inhibition of both receptors, D1 and D2, is necessary for influencing spike and wave discharges in this model.

Animals↗
PubMed1988

[Magnetic resonance imaging and herpetic encephalitis].

Cerebral lesions in two cases of herpetic encephalitis were detected by MRI using a spin-echo sequence and delayed echo signal recordings, whereas CT scans were normal. In one case pathology showed lesions to be more extensive than MRI anomalies. This suggests that even in the absence of EEG and CT anomalies, an encephalitis can be suggested by MRI.

Electroencephalography↗
PubMed1987

Effects of drugs affecting noradrenergic neurotransmission in rats with spontaneous petit mal-like seizures.

Wistar rats of a strain displaying spontaneous petit mal-like seizures and spike-wave EEG discharged (SWD) were injected i.p. with drugs affecting noradrenergic neurotransmission. The EEG and behavior were recorded. Drugs which decrease alpha-noradrenergic neurotransmission, prazosin (alpha 1-antagonist) and clonidine (alpha 2-agonist), increased SWD and were sedative in a dose-dependent manner. Drugs which increase alpha-noradrenergic neurotransmission, ST 587, cirazoline (alpha 1-agonists) and yohimbine (alpha 2-antagonist), reduced SWD and the latter two caused agitation. Drugs which interact with beta-noradrenergic transmission (salbutamol, isoprenaline and propranolol), monoamine oxidase inhibitors (nialamide and iproniazid), and a noradrenaline reuptake inhibitor (desipramine), did not affect SWD. These findings suggest that noradrenaline participates in the control of petit mal-like seizures in the rat, as in other types of seizures and other animal models.

Animals↗
PubMed1987

Platelet functions, alpha 2-adrenergic receptors and cytoplasmic free calcium are normal in the myotonic dystrophy of Steinert.

Platelet function tests were performed on 11 patients with myotonic dystrophy of Steinert (MD) and on 21 healthy control subjects. Using citrated platelet-rich plasma or washed platelets, MD patients had normal aggregation and secretion responses after stimulation with adrenaline, ADP, collagen, PAF, arachidonic acid and thrombin. Using intact and functional washed platelets, MD patients responded normally to adrenaline and had a similar affinity and number of alpha 2-adrenergic receptors as control patients as measured by [3H]dihydroergocryptine and [3H]yohimbine binding. In addition platelets from MD patients had normal basal and stimulated levels of cytoplasmic free Ca2+ as measured with the fluorescent Ca2+ probe quin2. Thus platelet functions, alpha 2-adrenergic receptors and cytoplasmic free Ca2+ are normal in MD.

Adenosine Diphosphate↗
PubMedDate not supplied

Cardiac transplantation in an incomplete Kearns-Sayre syndrome with mitochondrial DNA deletion.

A 38-yr-old man with external ophthalmoplegia, cardiac conduction abnormalities, hearing loss, and ragged-red fibres in skeletal muscle biopsy, developed severe signs of cardiac failure within a few months. Echocardiography and angiography demonstrated a dilated cardiomyopathy. Ubiquinone 140 mg day-1 did not stop the worsening of the cardiac status and cardiac transplantation was performed. Molecular analysis showed a heteroplasmic 4.5 kb mitochondrial DNA deletion in endomyocardial tissue. Eighteen months later, cardiac evolution is good and neurological status is stable.

Adult↗
PubMedDate not supplied

[Hypothyroid hypertrophic myopathy following mantle irradiation for Hodgkin's disease. A case].

The authors report a case of hypothyroid hypertrophic myopathy consecutive to mantle irradiation for Hodgkin's disease. A rise in TSH level is frequent after mantle irradiation and it justifies prolonged monitoring of these patients' thyroid function, in view of the risk of patent hypothyroidism and perhaps cancer. The patient's age, the pre-irradiation lymphography and the chemotherapy associated with radiotherapy are all factors that influence the incidence of thyroid dysfunction, but there is no agreement concerning their relative importance. Hypertrophic myopathies due to hypothyroidism are rare, and their dramatic clinical presentation contrasts with an almost normal muscle histology. Alterations of energy metabolism and changes in the properties of myosin induced by hormonal deficiency account for the muscular weakness of these patients. On the other hand, the mechanism of muscle hypertrophy remains controverted, the most probable theory being and increase in the number of myotubes. Following irradiation, notably for Hodgkin's disease, the frequency of hypothyroidism requires a regular and systematic laboratory follow-up. Replacement therapy must be instituted if the basal TSH level increases, even if the T4 level is normal.

Adult↗
PubMedDate not supplied

The role of calcium and magnesium ions in uptake of beta-amyloid peptides by microglial cells.

Amyloid peptides 1-40 and 1-42 (Abeta 1-40 and Abeta 1-42) are major components of diffuse and neuritic senile plaques present in the brain of patients with Alzheimers disease. Their interaction with microglial cells was studied using a system partly mimicking these plaques, which consisted in heat-killed yeast particles coated with either Abeta 1-40 or Abeta 1-42. Using these particles, it has been shown in our laboratory that LRP is involved mainly in the elimination of Abeta 1-42-coated heat-killed yeast particles and partly in that of Abeta 1-40-coated heat-killed yeast particles by microglial cells in culture. We show here that in the presence of calcium and magnesium ions extracellular chelators, namely EDTA (for both ions) and EGTA (for calcium ions), the internalization of coated heat-killed particles was impaired. In the presence of BAPTA-AM, an intracellular chelator of calcium ions and thapsigargin, an inhibitor of the endoplasmic reticulum calcium pump, no effect was observed on the phagocytosis of Abeta 1-40-coated heat-killed yeast particles, whereas that of Abeta 1-42-coated heat-killed yeast particles was affected. These results suggest that different signaling mechanisms are involved after the internalization of Abeta 1-40 and Abeta 1-42.

Amyloid beta-Peptides↗