Modélisation des flux cérébraux par une analogie électrique : validation par vélocimétrie IRM

The cine Phase-Contrast Magnetic Resonance (PCMR) sequence is the only noninvasive technique for the study of cerebrospinal fluid (CSF) oscillations. It can provide CSF and blood flow measurements throughout the cardiac cycle. To study cerebral hydro-hemodynamic, models have been developed; nevertheless the majority of these models did not take into account the CSF oscillations. The objective of this study was to establish reference values for cerebral hydro-hemodynamic and propose a new electrical model of the brain dynamics.Material and methodsCSF and blood flows were measured in 19 control subjects by PCMR imaging. Dynamic flow images were analyzed on dedicated software to reconstruct the flow curves during the cardiac cycle. An electrical analogue was realized. The inputs of the model were fed by PCMR arterial and venous flows to simulate CSF oscillations. The simulated CSF oscillations were compared to the measured CSF oscillations to validate the model.ResultsThe key parameters of the CSF and blood flow curves were obtained, e.g. total cerebral blood flow was 688 ± 115 mL/min, ventricular CSF oscillatory volume was 0.05 ± 0.02 mL/cardiac cycle, and the subarachnoid CSF oscillatory volume was 0.55 ± 0.15 mL/cardiac cycle. A close agreement was found between measured and simulated cerebral CSF oscillations.ConclusionThis study established the main values characterizing cerebral hydrodynamics in a control population. It provided a better understanding of the mechanisms of intracranial volumes regulation during the cardiac cycle. Our results are now used in clinical practice and the model proposed is effective to study cerebral hydro-hemodynamic.     

Évaluation des thérapeutiques ciblées en tomographie par émission de positons

Thanks to breakthroughs in drug design, new kinds of treatment in oncology have been developed. These new molecules target usually a precise molecular pathway proved to be involved in the development of a malignant disease. This led to the concept of targeted therapy. Therefore, the accurate selection of patients who may experience a clinical benefit of such treatments and the way to assess the response are still challenging issues. Molecular imaging with radiolabeled compounds seemed to be a very promising tool, as for example PET with ¹⁸F FluoroDeoxyGlucose (FDG), which allows to assess and to predict the response to a tyrosine kinase inhibitors more efficiently than conventional imaging tools. FDG is only a surrogate marker of cell proliferation. The common tools (clinical and radiological assessment) are no longer sufficient to predict the clinical efficacy of these new drugs. Molecular imaging should be added in the design of clinical trials in order to detect earlier pharmacodynamic effects, to select responding patients and to provide proofs of efficacy of these non-cytotoxic compounds. Molecular imaging databases have to be created and cross-matched to tumor sample collections, providing consequently new “dynamic” pathological resources.     

Bases moléculaires et cellulaires de l'invasion des cellules épithéliales intestinales par Shigella flexneri

A key step in the pathogenesis of shigellosis is the capacity of the causative bacteria, shigellae, to invade colonic and rectal epithelial cells in humans. This invasive process encompasses several steps: entry into epithelial cells by induction of a macropinocytic event caused by secreted Ipa proteins. The bacterium then escapes from the vacuole and reaches the cytoplasmic compartment in which it divides rapidly and becomes motile via the expression of a surface protein, IcsA, whose polar localization achieves directed polymerization of actin filaments that push the bacterial body forward. Bacteria then engage the inner face of the cellular membrane in the junctional area and form protrusions allowing their passage into the adjacent cell. Lysis of the double membrane eventually allows access to the cytoplasmic compartment of the adjacent cell, thus providing the bacterium with a very efficient mechanism of epithelial colonization.     

Évaluation de l’exactitude de latéralisation du foyer épileptogène par la tomographie par émission de positons au 18f-fluorodésoxyglucose dans le bilan préopératoire de l’épilepsie temporale : analyse visuelle simple et par index d’asymétrie inter-hémisphérique par soustraction d’images,analyse quantitative par statistical parametric mapping

IntroductionInter-ictal 18F-2-fluoro-deoxy-D-glucose-positron emission tomography (FDG-PET) plays a key role for the preoperative evaluation of patients with pharmacoresistant temporal lobe epilepsy. PET images are usually analyzed visually, a way that is reported to provide a high diagnostic value but that remains subjective, depending on the expertise and experience of the observer. By contrast, the voxel-based quantitative analyses, such as statistical parametric mapping (SPM), are objective and therefore, observer independent methods of analyses. In this study, the accuracy of the analyses of brain FDG-PET images to lateralize the temporal lobe epileptogenic zone was compared between: (1) a conventional visual method, (2) a quantitative SPM analysis, and (3) a visual analysis of inter-hemispheric asymmetry (IHA) obtained after images substraction.Materials and methodsFDG-PET scans of 31 patients presenting a severe temporal epilepsy and whom the temporal foci had been accurately lateralized (successful subsequent surgical treatment) were retrospectively analysed by (1) a consensual visual analysis from two experienced observers; (2) SPM analysis with voxel-wise comparisons of FDG-PET images of patients with those of age-matched healthy controls, using various statistical threshold (P) and cluster (k) values; and (3) visual assessment by the two same observers of images obtained for assessing the IHA. For this purpose, a flipped image was initially obtained by reversing in the left-right direction the FDG-PET images, which had been previously spacially normalized with the SPM template. Then, flipped and non-flipped images were substracted.ResultsThe temporal hypometabolic area was accurately identified: (1) by the conventional visual analysis in 87 % of patients and with a satisfactory interobserver reproducibility (interobserver Cohen's coefficient = 0.79); (2) by SPM analysis, in 90 % of patients (when using optimal thresholds of 0.01 for P value and of 50 voxels (400 mm³) for k value); and (3) with the visual analysis of IHA in 97 % of patients with an excellent interobserver reproductibility (interobserver Cohen's coefficient = 1).ConclusionIn patients presenting severe temporal epilepsy, visual assessment of FDG-PET images from IHA seems more accurate for lateralizing the epileptogenic temporal areas when compared with either conventional visual or quantitative SPM analyses. Moreover, this method is very easy to use in clinical practice, contrary to the quantitative method using SPM     

Transmission héréditaire de l’information épigénétique par le gamète mâle

What determines phenotype is one of the most fundamental questions in biology. Historically, most studies have focused on genetics but more recent studies have revealed the existence of epigenetic modifications that are not based on DNA sequencing but are essential for appropriate gene expression. Importantly, these epigenetic modifications can be inherited by the offspring. Thus, both male and female gametes contain inherited epigenetic information.     

La dysfonction éréctile au Sénégal: Profil épidemiologique

Methodology

This was a transverse randomized survey of subjects over the age of 18 years. Subjects completed a self-administered questionnaire composed of two parts. The first part contained information on demographic characteristics, associated diseases, erectile dysfunction and associated sexual disorders and the second part was based on IIEF5. Two groups were identified: a group with erectile dysfunction (ED group) and another group without erectile dysfunction (No ED group). Differences between the two groups were considered to be statistically significant for p ≤ 0.05 on the Chi-square test.

Results

The global prevalence of erectile dysfunction was 26%. The prevalence by age-group revealed a progressive increase of ED with age from 11% between 20 and 30 years to 76% between 70 and 80 years. The rate of polygamous men was significantly higher in the group with ED (29.2%) compared to the group without ED (6.6%) (p < 0.0001) and the severity of ED increased in relation to the number of wives. Chronic alcoholism was significantly more frequent in the group with ED (p = 0.023). The frequency of ED increased with the duration of cigarette smoking from 11.9% for less than 5 years, 16.9% between 5 years and 10 years and 71.2% for more than 10 years. Some diseases (diabetes, hypertension and depression) were significantly more frequent in the group with ED. Analysis of the type of ED revealed that secondary erectile dysfunction was more frequent (95.6%) than primary erectile dysfunction (4.4%). Associated sexual disorders were significantly more frequent in the group with ED.     

Problèmes écologiques posés par l'observation des Ascidies dans la zone infralittorale

Résumé 1. La répartition des Ascidies dans la zone infralittorale ne peut être expliquée par l'influence des facteurs écologiques généralement mesurés dans la zone des marées.2. L'observateur dispose de trois critères principaux pour juger de l'action des facteurs écologiques non mesurables: (a) l'abondance relative des espèces renseigne sur la balance des facteurs favorables et défavorables ainsi que sur les besoins de surface de fixation; (b) l'état de croissance et la maturité sexuelle précoce permettent de détecter l'influence de facteurs défavorables; (c) la disposition par rapport au substrat permet de juger des facteurs lumière, couleur du substrat, orientation par rapport au substrat. L'étude comparée de la disposition sur fonds rocheux et sédimentaires permet de mettre en évidence l'importance du nuage particulaire soulevé par les courants de fond.3. Scaphandre, Soucoupe et Troïka sont des instruments de choix pour l'analyse et l'expérimentation sur le «gregariousness phenomenon» et sur la formation des associations biologiques, dans l'infralittoral rocheux et plus encore sur les fonds chalutables.

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Ökologische Probleme, die sich aus Beobachtungen an Ascidien im Infralitoral ergeben

Kurzfassung Die Verbreitung der Ascidien im Infralitoral kann nicht durch den Einfluß der im allgemeinen für die Gezeitenzone bedeutsamen ökologischen Faktoren erklärt werden, da diese im Infralitoral nur geringen Veränderungen unterliegen. Hinsichtlich des Vorkommens und der Verteilung der Ascidien läßt sich der Einfluß der Umwelt anhand folgender Kriterien erschließen: (a) Die relative Häufigkeit der Arten gibt einen Aufschluß über das Gleichgewicht zwischen günstigen und ungünstigen ökologischen Faktoren sowie über die Substratansprüche einer Species. (b) Der Einfluß ungünstiger Faktoren läßt sich anhand des Wachstums und des vorzeitigen Eintritts der Geschlechtsreife feststellen. (c) Die Anordnung auf dem Substrat ermöglicht die Beurteilung der Faktoren Licht, Farbe des Substrats und Orientierung im Verhältnis zum Substrat. Vergleichende Untersuchungen der Anordnung auf felsigem und sedimentärem Untergrund gestatten Aussagen über die Bedeutung der Bodenströmungen. Es wird auf die Notwendigkeit hingewiesen, moderne Unterwassergeräte und Tauchausrüstungen einzusetzen, um Untersuchungen über die Aggregationsphänomene und eine Analyse der Lebensgemeinschaften in der infralitoralen Felszone sowie auf dem Meeresgrund durchführen zu können.

     

À propos de quelques questions éthiques soulevées par la maladie d’Alzheimer

This paper tackles two ethical problems often raised by Alzheimer’s disease and associated disorders: the issue of diagnosis disclosure and the issue of autonomy (or consent). The first part of the paper begins with a critical analysis of the literature on diagnosis disclosure. The authors try to understand why the problem is such a hotly debated issue. They then propose some theoretical and practical perspectives. For example, they suggest that one should allow the patients themselves to designate the persons who should be informed about their health status. They also wonder whether it is really coherent to communicate the diagnosis without discussing its known consequences. The second part of the paper begins with an analytical presentation of the problems one encounters when attempting to respect the autonomy of alzheimer patients. Then the authors discuss the interests and the limits of the proposed solutions to these problems. Finally, they discuss the analyses by two contemporary philosophers (Dworkin and Jaworska) concerning the question: to what extent does Alzheimer’s disease undermine the capacity for autonomy?     

études sur les phénomenes électrocapillaires

Sans résuméI. Analyse électrocapillaire des matières colorantes. Rev. gén. Mat. Col. 1926 Vol. 30 pp 34–45II. Phénomènes électrocapillaires et le problème du cancer. Arch. Med. Exper. 1926 Vol. I p 381III. Phénomènes électrocapillaires et l'antagonismes microbiens. Bol. Istituto Sier. Milano 1927 Vol. VI p 313.     

Considérations sur trichophyton violaceum et sur son épidémiologie en Roumanie; L'Aspect clinique des lésions causées par ce dermatophyte

Résumé Exposé sur 1510 cas (944 hommes et 566 femmes) de mycoses àT. violaceum, observés depuis avril 1945 jusqu'à juillet 1964, à la Clinique et au Centre Dermato-Vénéréologique, hôpital Colentina Bucarest. Jusqu'en 1954 c'était le premier parasite des teignes. Cette première place revient à présent auM. audouinii. Les épidémies àT. violaceum, observées par l'auteur, ont eu un caractère plutôt familial et les foyers épidémiques, contrairement aux microsporons, ont été éliminés. Le cuir chevelu a été le siège principal de la mycose chez 1463 malades. La barbe a été envahie chez 11, les sourcils chez 2, les ongles chez 21 malades. Chez 110 malades les plaques du cuir chevelu étaient légèrement inflammatoires et chez 4 il y avait un kérion de Celse. Chez 153 malades (10,12%) les plaques ont évolué vers l'alopécie atrophique. La trichophytie de l'adulte a été dépistée chez 32 personnes (5 hommes et 27 femmes) dont l'âge était compris entre 22 et 65 ans. Chez 6 malades il s'agissait d'une infection récente. Chez les autres 26, elle évoluait depuis l'enfance (trichophytie chronique).

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Summary From April 1945 to July 1964, in the Dermato-Venerological Department of Colentina Hospital — Bucarest, studies were carried out on 1510 cases (944 males and 566 females) of ringworm caused byT. violaceum. In tinea capitis this fungus predominated until 1954. Later the first place was taken byMicrosporon audouinii. Epidemics withTrichophyton violaceum occurred only among small groups of persons, especially in families. Infections did not become widely epidemic, like those with microsporons. The scalp was involved in 1463 patients, the beard only in 11, the eyebrows in 2 and nails in 21 patients. In 110 patients the patches became inflammatory (moderately) and in 4 ones they turned into kerion. In 153 patients (10,12%) the patches turned into atrophy like in pseudo-pelade of Brooq. Trichophytosis of adult was observed in 32 patients (5 males and 27 females) aged 22 to 65 years. In 6 patients, the infection was recent, but the other 26 acquired their ringworm in infancy (chronic trichophytosis of adult).

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TRAVAIL DÉDIÉ AU PROFESSEUR ST. G. NICOLAU, MEMBRE DE L'ACADÉMIE ROUMAINE, À L'OCCASION DE SON 90-ÈME ANNIVERSAIRE     

Mise en évidence par immunofluorescence des cellules sécrétrices de glucagon dans le pancréas endocrine du poisson téléostéen Xiphophorus helleri H.

Summary The ruthenium red staining of the surface coats was studied in the adrenal medullary cells of golden hamster. Both immersion and perfusion fixation was used with the ruthenium red containing fixative, however, only the perfusion fixation gave positive results. A rather thick electron dense ruthenium red positive layer was found on the plasma membrane of the endothelial cells, around the capillaries in the basal lamina, in the basement membrane of the chromaffin cells as well as on the apical and lateral cell surfaces of the adrenomedullary cells. Coated pits and coated vesicles usually showed an intensive ruthenium red staining, but the other cell components in the cytoplasm did not. On the basis of these observations author suggests that the ruthenium red positive material corresponds to acidic mucopolysaccharides in the hamster adrenal medulla, and its wide-ranging occurrence is indicative of its significance in the secretion process of catecholamines.Wellcome Research Fellow.     

Dysfonction érectile: profil épidémiologique dans une population de sujets retraités au Sénégal

Introduction

Erectile dysfunction (ED) presents particular profile among retired population. The purpose of this study is to report epidemiological aspects of that ED and analyze its risk factors.

Methods

It was a prospective study realized during a 12 months period, in the Centre medico-social of Institution de Prévoyance Retraite in Sénégal (IPRES). All data have been collected thanks to a questionnary that patients had to fill it themselves. Selected patients were at least 55 year-old. Among 552 given questionnary, 537 were selected.

Results

We found that 60,7 % (n=326) of this studied population presented an ED. The mean age of the subjects was 68 ± 6.7 years in the ED group versus 65 ± 6.2 years in the non-ED group. The average duration of tobacco abuse was 24.3 ± 14.4 years. The mean duration of alcohol exposure was 28.6 ± 15.5 years ranging from 3 to 63 years. Diabetes was reported in 67 cases (12.5 %) and 18 (3.3 %) of ED patients have been screened and diagnosted for diabete during the study. The ED lasted in average 4.2 ± 4 years with ranged from 6 months to 20 years.

Conclusion

ED is a good indicator of quality of life. However, psychological disturbances, socioeconomical and medical troubles noted during the period of compulsory retirement have a relevant impact in the appearance or worsening of ED.     

Les échanges de nourriture liquide entre Abeilles aux températures élevées

Conclusion Nous avons démontré des échanges assez importants du liquide entre les Abeilles aux températures élevées. Cette répartition est exprimée pour la première fois quantitativement. Nous supposons que c'est un phénomène d'une réaction thermorégulatrice sur le plan social. Nous sommes en train de vérifier si cette réaction crée un microclimat différent autour des Abeilles dans ces conditions expérimentales.     

Influence d'une lame métallique sur la distribution de la dose dans le plexiglas irradié par des électrons de haute énergie

Résumé Une lame hétérogène deZ plus élevé que celui de l'eau, provoque dans un faisceau d'électrons de haute énergie une modification de la distribution de la dose en profondeur.La dose est augmentée au contact et au voisinage immédiat de la lame hétérogène, tandis qu'elle est diminuée à plus grande distance.Dans le cas habituel de la radiothérapie, où la lame hétérogène est constituée par une épaisseur limitée d'os, et de l'expérimentation radiobiologique, où l'hétérogénéité est constituée par les parois de verre, le surdosage reste inférieur à 5% pour les électrons d'énergie comprise entre 10 et 20 MeV.La distribution de la dose en profondeur est approximativement représentée par la courbe standard, si les profondeurs sont exprimées en masse surfacique (g/cm²).On peut donc admettre une épaisseur d'absorption équivalente (A E T) égale à l'épaisseur réelle multipliée par la densité de la lame hétérogène.Cependant dans les expérimentations rigoureuses qui exigent une précision élevée, le calcul de la dose en profondeur par l'A E T, peut ne pas être satisfaisante, et la mesure directe est indispensable.     

Méthodes d’évaluation des érections automatiques nocturnes dans les dysfonctions érectiles

For more than 25 years, the study of nocturnal penile tumescence (NPT) has been a basic element in the investigation of erectile dysfunction. Numerous methods have been proposed; always non-invasive, generally not very onerous and easily achieved. They require little more than a basic understanding of physiology, and knowledge of the qualitative and quantitative criteria for assessing NPT, in order to avoid any incorrect or dangerous interpretation. Based on more than 8000 nights of recordings, it is possible to separate the advantages, inconveniences and operating costs of the major instrumentation options. Although rather unsatisfactory, plethysmography and rigidometry of NPT have become the cornerstone for investigating erectile dysfunction. Always necessary, sometimes these examinations alone are sufficient, for example when they are normal and allow confirmation of a psychogenic aetiology of impotence. In other situations they must be supplemented with other complementary examinations, in which case the results show an 80% correlation with NPT. A revival of interest in the study of NPT will occur once we have achieved the impossible: the availability of a cheap instrument allowing recording of turgidity, rigidity and REM sleep, without discomfort and in the patient’s home.