Testostérone et contrôle central de l’érection

Testosterone orchestrates the perinatal organization and activation of cerebral and spinal neuronal structures involved in the expression of male sexual behaviour in adults. The present review briefly describes testosterone effects in the regulation of sexual motivation and erection, as well as the genetic models developed to date in order to unravel its central mechanisms of action.     

Epidémiologie,diagnostic et pronostic du cancer de la prostate

Prostate cancer is the most frequent of cancers and represents the third leading cause of death by cancer, for men over 50 years, in France and Europe. The incidence decreases since about ten years. Mass screening is not recommended. Individual early diagnosis is based on a yearly exam including Prostate Specific Antigene (PSA) blood test and a digital rectal exam. The target for this diagnostic approach are men from 50 to 75 years with more than 10 years of life expectancy. A series of prostatic biopsy are carried out in case of clinical and/or biological prostate cancer suspicion. The additional examinations recommended in the assessment of extension of prostate cancer with intermediate and high risk are: MRI, bones scintigraphy, scan CAP (metastatic stage), and sometimes Choline PET-CT. Curative treatments are proposed to men with a probability of survival over 10 years, suffering from localized or locally advanced cancer. Gold standard treatments are: active surveillance, radical prostatectomy, brachytherapy, radiotherapy alone or with surgery and/or hormone therapy. Experimental treatments of localized tumors are: focal treatments (phototherapy dynamic, high intensity focused ultrasound). For the more advanced forms, the interest of early chemotherapy is extensively studied.     

Les hypogonadismes hypogonadotrophiques congénitaux masculins, quelles données récentes ?

Congenital hypogonadotropic hypogonadism (CHH) is a very heterogeneous group of disorders resulting from a deficiency of pituitary gonadotropin secretion that is related to defective migration of GnRH neurons or dysfunction of pituitary or hypothalamic system. Gonadotropin deficiency remains a rare cause of hypogonadism; its prevalence is not definitely established and is thought to be about 1/5,000. It is responsible for clinical symptoms that are related to low testosterone levels. The classification of CHH which was previously based on presence of or lack of anosmia has been enriched in the last two decades by the discovery of many genes involved. This allowed a better understanding of CHH and led to new approaches regarding genetic counselling.     

Tomographie par émission de positons et cancer de la prostate

Positron emission tomography (PET) is a major imaging modality in oncology. Fluorodeoxyglucose (FDG) PET is of limited usefulness in prostate cancer, be it for initial staging or for detection of recurrence. New PET tracers could improve PET performances in prostate cancer staging and when recurrence is suspected. Lipid metabolism tracers, such as choline and fluorine-18-labelled choline analogues, seem to be promising in these indications. The impact of these PET examinations on patient management should be further evaluated, taking into consideration the new therapeutic strategies, in particular salvage local treatment in case of isolated local recurrence.     

Scintigraphie de perfusion et scintigraphie de la neurotransmission dopaminergique présynaptique : le traitement des données

The purpose of this article is to point out the great principles for processing in cerebral tomoscintigraphy while being focused on the key points of the process according to the recommendation of the European Academy of Nuclear Medicine and the French Society of Nuclear Medicine. We will insist, however, on the methods of tomographic reconstruction. Indeed, progress of data processing makes it possible today to use in clinical routine, the iterative methods of reconstruction which were reserved until these last years for research. For as much, the method of filtered back projection remains still commonly used. It appeared necessary to us to point out the base of these various methods of reconstruction and to underline some essential key points for their use. Obviously, the quality of an examination is not limited to the reconstruction. We will underline at the end of this article the importance of the other chain links of treatment, as the quality control of the images, the volume reorientation, as well as the principles of the semiquantification.     

Thérapies ciblées et biomarqueurs compagnons dans les cancers de la prostate métastatiques

Treatment of castration-resistant prostate cancer has undergone a revolution over the past 3 years with the approval of five new therapies, including new hormonal therapies (abiraterone and enzalutamide) and bone-targeted agents (denosumab, radium-223). New targeted agents have improved survival and quality of life. Currently, companion biomarkers are lacking for a better individualization of treatment.     

Imagerie moléculaire de la maladie de Parkinson : données actuelles

During the last years, knowledge and concepts concerning Parkinson's disease and other parkinsonian syndromes have progressed: a concept of network pathology with different clinical presentations and evolutions, involving several neurotransmission pathways succeeeded the single dopaminergic lesion concept. Imaging also changed with the development of MRI. In this context, the aim of this work is to bring up-to-date methodology and clinical contribution of dopaminergic neuron imaging. Nigrostriatal neuron imaging (dopamine transporter imaging) contributes to diagnosis of Parkinson's disease and Lewy body dementia. Dopamine receptor imaging mainly helps in differential diagnosis of parkinsonian syndromes (Parkinson's disease and Parkinson plus syndromes). The ongoing development of dopaminergic, cholinergic, serotoninergic tracers and the recent emergence of amyloid plaques and neurofibrillary tangles imaging open perspectives for molecular imaging and care of neurodegenerative diseases.     

Quelques données sur l'ultrastructure de récepteurs gustatifs de l'antenne de la fourmi Camponotus vagus scop. (Hymenoptera,Formicinae)

Résumé Le dernier article du funicule de l'antenne de Camponotus vagus possède un petit nombre de soies sensorielles articulées, innervées chacune par six neurones.Les six dendrites sont d'abord emballés dans une gaine cuticulaire commune; cette dernière, par un processus d'invagination se divise en deux. L'une des deux gaines ainsi formées accompagne l'un des dendrites — de gros diamètre — jusqu'à l'articulation; à ce niveau le dendrite présente une densification apicale tout à fait caractéristique des mécanorécepteurs. L'autre enveloppe cuticulaire entoure les cinq dendrites restants et les accompagne jusqu'à l'extrémité de la soie perforée par un pore unique qu'ils atteignent sans jamais se ramifier. Le role de la double fonction sensorielle de ces récepteurs est discuté.

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Some ultrastructural results obtained on the antennal gustative receptors of Camponotus vagus Scop. (Hymenoptera, Formicinae)

Summary The antennae of the worker of Camponotus vagus bears sensory articulated setae on the last article of the funiculus; each of them is innervated by six neurons. The six dendrites are initially surrounded by a common cuticular sheath which divides into two by an invaginating process. One, with the largest dendrite inside, extends to the articulation, and shows an apical densification characteristic of mechanoreceptors. The second cuticular sheath surrounds the five other dendrites and reaches the apex of the seta, which is open by only one pore. The dendrites are not ramified. The double sensory function of the receptor is discussed.

     

Le nouveau paysage du cannabis I. Données récentes sur la neurobiologie des endocannabinoïdes et du cannabis

Among all the drugs of abuse cannabis is the only one containing an active principle that can be stored in the body for several weeks, delta-9-Tetrahydrocannabinol (Δ9-THC). It induces both psychic and physical dependency, which are masked because the disappearance of Δ9-THC from plasma corresponds to its storage in lipids, especially in cerebral lipids. In the brain Δ9-THC mimics, in a non regulated, diffuse and intense manner, the neuromodulation which endocannabinoids (anandamide, 2-arachidonyl-glycerol, etc.) physiologically und subtly exert through the stimulation of specific receptors, the so-called CBl receptors. These receptors have an influence on a great variety of psychological functions. For instance, at the hippocampal level receptor reserve is high, and it allows the development of a maximal response even though only a low proportion of these receptors are stimulated. This occurs even for low doses of Δ9-THC. The desensitization / down regulation of these receptors has no functional consequences since they always remain numerous enough to ensure the function. Thus the Δ9-THC-induced cognitive disturbances persist as long as cannabis use persists. On other systems, without CBl receptor reserve, the long lasting use of Δ9-THC induces a desensitisation / down regulation of CBl receptors, leading to a tolerance to its effects.     

Le nouveau paysage du cannabis II. Données récentes sur la psychotoxicité du cannabis

After delta-9-tetrahydrocannabinol (Δ9-THC) has supported the anandamidergic tone, thereby increasing its anxiolytic and antidepressant effects, it loses its efficacy in this respect. Anxious and/or depressive troubles which could have prompted the abuse of cannabis then reappear more intensely. They peak when consumption is completely stopped. Cannabis consumption may contribute to polydrug abuse. Its association with tobacco makes it more difficult to give up both substances of abuse. Cannabis use encourages the consumption of alcohol and this association is especially deleterious as regards car accidents. Δ9-THC sensitises cannabis abusers to perceive the appetitive effects of heroin in a more acute manner. Cannabis consumption also makes withdrawal symptoms associated with heroin abuse more severe. Cannabis appears to be able to reveal schizophrenia in patients bearing a neurobiological vulnerability substratum to this disease. It seems especially appreciated by people suffering of negative symptoms of schizophrenia, which could prompt them to abuse cannabis, and then triggering the positive symptoms of the disease. These positive symptoms are particularly resistant to treatment with antipsychotic medication when cannabis abuse is continued. All this recent data necessitates extreme care with this drug of abuse, whose dangerous effects are becoming more and more known.     

Activités pharmacodynamiques comparées de la 5-hydroxytryptamine et de la 5-methoxytryptamine

Methylation of 5-hydroxytrptamine (5-HT) into 5-methoxytryptamine (5-MT) changes little of its action on the blood pressure of the rat and of the cat, and on the contraction of the isolated ileum of the rat. Methylation increases slightly the potentiating action of 5-HT on the presynoptic orthosympathetic stimulation of the nictating membrane of the cat. Large doses of 5-MT given previously do not influence the response of the rat blood pressure to the 5-HT.Some inhibitors of the action of the 5-HT have a similar effect on the response to the 5-MT but at a lower dose level.     

Les résidents et l'enseignement: revue de la littérature.

We reviewed the available data on residents'' teaching role in the clinical setting to develop programs to improve their teaching skills. Articles published from 1966 to 1989 were identified through a computerized search of MEDLINE, and the bibliographies of identified papers were reviewed. Articles directly related to the topic were included and analysed. Taking into account their quality, we extracted data relevant to specific issues. Approximately 15% to 25% of an average work week was spent by residents in different teaching activities. Students acknowledged the importance of their contribution to clinical teaching. Residents benefitted from teaching by increasing their medical knowledge and promoting the development of important attitudes. Insufficient preparation for this task and the numerous practical problems faced by residents may explain their modest performance as teachers. Nevertheless, programs directed to residents might improve the quality of their teaching. We suggest some guidelines for the development of programs to improve their teaching skills and for future research.