Place de la TEP au 18FDG dans la localisation de primitifs néoplasiques

Carcinomas of unknown primary site (CUP) and paraneoplastic syndromes have the common characteristic that an extensive conventional biological and imaging analysis fails in some instance to detect the primary tumour. FDG-PET becomes recognized to provide interesting information in the case of “head and neck” CUP as well as in the case of neurological paraneoplastic syndromes biologically well defined. When, either CUP or paraneoplastic syndromes, are less defined, FDG-PET will not provide as much information as in the previous situation, although it can help in the etiologic diagnosis (oncologic or not) in some cases.     

L’apport de la neuro-imagerie dans la maladie d’Alzheimer

Today, the role of neuroimaging in the diagnosis of Alzheimer’s disease (AD) extends beyond its traditional role of excluding other conditions such as neurosurgical lesions. Modern challenges for neuroimaging techniques aim to contribute to the early diagnosis of AD. Early diagnosis includes recognition of pre-demented conditions, such as people with mild cognitive impairment (MCI) or with high risk of developing AD. In addition, early diagnosis would allow early treatment using currently available therapies or new therapies in the future. In this article, we will present the modern role of neuroimaging in AD. Structural MRI can detect and follow the time course of medial temporal lobe atrophy as a surrogate marker for the pathological process. New MRI techniques and image analysis software can detect subtle brain diffusion, perfusion or metabolic changes thus providing new tools for studying the pathological process. New ligands are also available for studies using tracers and positron emission tomography.     

Facteurs impliqués dans le remodelage de la chromatine au cours de la spermiogenèse

Round spermatids are post-meiotic cells with a haploid genome contained in a nucleus, with a structure initially similar to that of the somatic cell nucleus. During spermatogenesis, the spermatid nucleus undergoes drastic remodelling during which it first elongates and then condenses into the very specific and tightly packaged structure of the sperm nucleus. During this remodelling dthe histones are replaced by transition proteins, which, in turn, are replaced by protamines, the specific nuclear proteins of the spermatozoa. Immediately prior to their replacement, the histones are hyperacetylated. The first part of our work was to precisely characterise the changes in histone acetylation during murine spermatogenesis. We have shown that the core histones H2A, H2B, H3 and H4 are hyperacetylated in the elongating spermatids. We have also shown that these changes in acetylation are associated with degradation of the enzymes responsible for histone deacetylation, histone deacetylases or HDACs, while histone acetyl transferases are still present in these cells. The histone acetylation pattern was also investigated during human spermatogenesis, revealing that histone hyperacetylation in the nucleus of elongating spermatids, which appears to be conserved during the course of evolution, also occurs during human spermatogenesis. Moreover, our data obtained from the testes of men with severely altered spermatogenesis, including SCO syndromes (Sertoli Cells Only Syndromes), show that a global hyperacetylation of the Sertoli cell nuclei is associated with an absence of meiotic and post-meiotic cells. This suggests that the global histone acetylation variations observed during spermatogenesis are part of a signalling pathway involving germ cell — Sertoli cell communication. Altogether, these data provide a basis for a better understanding of the mechanisms and identification of the factors involved in post-meiotic remodelling of chromatin.     

Variations saisonnières de la production primaire dans les eaux de surface de la rivière du Saguenay

Experiments of primary production were carried out at weekly intervals in the surface waters at one station (maximum depth of 20 m) in the Saguenay River, near Chicoutimi, during May–December 1978. The photic zone was very thin (maximum depth of 2 m). Phosphates are very low during the season sampling (maximum of 0.1 µat-g.^–1). Maximum of production rates and biomass are respectively 3.5 mg C.m^–3.h^–1 and 3.7 mg.m^–3. The river receives both industrial and urban runoff. Trace metals (Mercury, Copper, Lead, and Iron) seemed to be one of the important limiting factors for phytoplankton growth.

     

Explorations cardiologiques nucléaires dans la cardiomyopathie de Takotsubo

Transient left ventricular apical ballooning syndrome, also known as Takotsubo cardiomyopathy (TTC) was described for the first time in Japan in the earliest nineties. It represents 1 to 2 % of acute cardiac events and mimics closely acute myocardial infarction. The aim of this study was to investigate ^99mTc-tetrofosmine or ²⁰¹Thallium myocardial Single Photon Emission Computed Tomography (SPECT), ¹²³I-metaIodoBenzylGuanidine (¹²³I-mIBG) myocardial SPECT and myocardial Positron Emission Tomography using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) in patients with TTC, assessing respectively left ventricular perfusion, innervation and metabolism. We studied four patients (three females) with TTC. We performed two weeks after acute phase (subacute phase) myocardial perfusion SPECT and ¹²³I-mIBG myocardial SPECT for each patient. Two of them underwent myocardial PET with FDG. Then, we assessed left ventricular innervation and metabolism three months (chronic phase I) and more than six months (chronic phase II) after the acute phase. We compared the discrepancies between radionuclides uptake in the left ventricular apical region during a follow-up period of more than six months. In subacute phase, perfusion SPECT was normal for each patient. Conversely, ¹²³I-mIBG SPECT and FDG-PET showed concordant apical uptake defect. This perfusion-metabolism pattern called “inverse flow-metabolism mismatch” is the metabolic state of stunned myocardium. After three months, we found improvement of apical tracer uptake in both FDG-PET and ¹²³I-mIBG SPECT. These findings suggest that TTC is characterized by myocardial apical stunning which is related to a disturbance of cardiac sympathetic innervation. ¹²³I-mIBG SPECT might be useful to diagnose earlier this pathology and to rule out acute myocardial infarction.     

Performances diagnostiques actuelles du coroscanner dans la détection de la maladie coronaire

Recent advances in multislice computed tomography (MSCT), which might represent a minimally invasive alternative to coronary angiography (CA), have allowed the ability to analyze coronary arteries. In this review, we present the current diagnostic performance of MSCT, as compared with the reference standard (CA), for the assessment of native coronary arteries, coronary in-stent restenosis and coronary artery bypass graft.     

Influence de la concentration du glucose et de l'azote sur la morphologie de Candida albicans et la formation de ses chlamydospores dans un milieu de culture synthétique

Résumé Candida albicans a été cultivé à l'obsurité, à 28 °C, dans un milieu de culture synthétique liquide dans lequel on fait varier les concentrations de glucose et d'azote. Des indices de chlamydosporulation ont pu etre calculés pour les milieux contenant au plus 0,08 g/l de glucose. Lorsque la concentration de glucose est plus importante, les thalles pseudomycéliens portent, dans certains cas, de nombreuses chlamydospores, mais aussi des chaines de cellules à contenu dense; ces thalles bourgeonnent des éléments levuriformes qui se détachent et continuent à bourgeonner dans le milieu de culture. Les différentes morphologies rencontrées sont décrites, illustrées et ordonnées en fonction des concentrations de glucose et d'azote du milieu.

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Candida albicans was grown in the darkness, at 28 °C, in a synthetic medium in which glucose and nitrogen concentrations were varied. Numeric appraisal of the chlamydospore index was possible only in the medium where glucose concentration was 0,08 g/l or less. When the glucose concentration raised, pseudomycelial thalli bore numerous chlamydospores but sometimes also chains of cells with a dense granular content. These thalli bud yeast cells which separate and bud again in the medium. The different morphological aspects of the cultures are decribed, illustrated and classified according to the glucose and nitrogen concentration of the medium.

     

Localisations ultrastructurales dans le labyrinthe du placenta de chatte de la phosphatase acide de la thiamine pyrophosphatase et de la coloration par l'acide phosphotungstique à bas pH

Résumé Les localisations de la phosphatase acide (ACPase) et de la thiamine pyrophosphatase (TPPase) ont été recherchées dans le labyrinthe du placenta de chatte, durant les derniers jours de la gestation. L'ACPase est essentielement localisée au niveau du syncytiotrophoblaste, et dans la substance inerte interstitielle (S.I.I.) qui sépare les tissus foetaux des tissus maternels. La présence du produit de réaction, dans la lumière du système tubulaire lisse du syncytiotrophoblaste communicant avec la S.I.I., semble indiquer une origine syncytiotrophoblastique de l'activité ACPase de la S.I.I.L'activité TPPase se manifeste dans le syncytiotrophoblaste, rarement dans la Golgi mais toujours dans la lumière du système tubulaire. La présence de ces tubules TPPase positifs à la proximité de l'appareil de Golgi, semble indiquer une origine golgienne de ces structures qui pourraient véhiculer les phosphatases vers la S.I.I.Après action de l'acide phosphotungstique à bas pH, le cell coat de la face hémale de l'endothélium maternel est toujours bien visualisé, par contre la surface du syncytiotrophoblaste baignée par la S.I.I. n'est jamais marquée. Le dépôt intense de la lumière des tubules est en continuité avec celui de la S.I.I.L'activité ACPase de la S.I.I. doit permettre la dégradation de molécules maternelles durant leur transfert vers le sang foetal. La S.I.I. semble correspondre physiologiquement à la zone tampon immunitaire de l'interface des tissus maternels et foetaux.

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Ultrastructural localization of acid phosphatase and thiamine pyrophosphatase activities and of phosphotungstic staining at low pH in the placental labyrinth of the cat

Summary The localizations of acid phosphatase (ACPase) and thiamine pyrophosphatase (TPPase) activities were studied in the placental labyrinth of the cat during the last days of gestation. ACPase activities were observed essentially in the syncytiotrophoblast and in the interstitial inert substance (S.I.I.) that separates maternal from foetal tissues. Reaction product was localized in lysosomes, multivesicular bodies, and in the network of smoothmembraned tubules which open on the cell surface of the syncytiotrophoblast facing the S.I.I. The S.I.I. exhibit a strong activity, probably of syncytiotrophoblastic origin.TPPase activities were found in the syncytiotrophoblast, rarely in the Golgi apparatus but always in the lumen of the network of smooth-membrande tubules. The S.I.I. shows a moderate activity. These TPPase positive tubules being frequently observed very close to the Golgi cisternae, it is proposed that they arise from the Golgi complex and convey phosphatases to the S.I.I.After phosphotungstic acid staining at low pH, luminal surface coat of maternal endothelium is always strongly and continuously visualized, while the plasma membrane of the syncytiotrophoblast facing the S.I.I. is never stained. Staining is intense in the lumen of tubules, and continuous with the stain of the S.I.I.ACPase activity of the S.I.I. could be implicated in enzymatic degradation of maternal molecules during their transfer from maternal to foetal blood. The S.I.I. may correspond to the immunological buffer zone at the interface between maternal and foetal tissues.

     

Étude de la décomposition de la matière organique dans le sol au moyen de carbone radioactif

Conclusions Par l'emploi de substrats radioactifs, il a été possible de montrer que le glucose, le ray-grass tel quel, la fraction soluble, les hemicelluloses et la fraction cellulosique du ray-grass ne sont pas, dans les conditions expérimentales appliquées, entièrement transformés en CO₂ dans le sol après une période de deux mois.La décomposition du glucose est plus rapide que celle des hemicelluloses et celle-ci est plus rapide que celle de la fraction cellulosique. Pour le glucose et pour la fraction cellulosique, 11% et 15% respectivement ne se retrouvent pas sous forme de C¹⁴O₂ tandis que pour la fraction soluble, pour les hemicelluloses et pour le ray-grass tel quel, c'est près de 20% qui ne sont pas oxydés en CO₂.La décomposition de chacun de ces substrats radioactifs donne encore lieu à la production de produits organiques radioactifs que l'on trouve dans la fraction des substances solubles, dans la fraction groupant l'- et le -humus et dans l'humine. La radioactivité de cette dernière fraction est du même ordre de grandeur que la somme des deux autres fractions.Travail effectué sous les auspices de l'Institut pour l'Encouragement de la Recherche Scientifique dans l'Industrie et l'Agriculture (I.R.S.I.A.).     

Structure de la strate arborescente dans un site de la forêt de montagne du Rwanda (Arfique centrale)

Résumé Dans un site de la forêt de montagne du Rwanda, diverses méthodes d'étude de la structure de la strate arborescente sont présentées. Grâce à diverses méthodes d'ordination et de classification, il est possible de représenter la distribution de la surface terrière de plusieurs espèces d'arbre le long d'un gradient d'humidité. L'analyse des coefficients de corrélation entre individus adultes et jeunes fait apparaître des différences entre l'écologie des arbres jeunes et adultes; à cause de la variance élevée des données, une standardisation est nécessaire. Le diamètre de l'arbre de surface terrière moyenne est une valeur de synthèse très intéressante sur le plan écologique. Les caractéristiques dendrométriques et écologiques de 4 groupements végétaux sont présentées; les courbes de fréquences de circonférences de trones sont un complément intéressant dans la compréhension de l'écologie des espèces.

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Summary In a site of the Rwanda upland forest, different methods of study of the tree layer structure are presented. By using diverse ordination and classification methods, it is possible to represent the distribution of the basal area of several species along a moisture gradient. The analysis of the correlation coefficients between adult and young individuals of a same species exhibits differences in the ecology of young and adult trees; because of the high data variance, a standardization is necessary. The diameter of the tree of mean basal area is a very interesting synthesis value from an ecological point of view. The ecological and dendrometric characteristics of four groupings are presented; the frequency curves of trunk girth are an interesting complement to the understanding of the species ecology.

Toutes les données présentées ont été rassemblées pendant notre séjour à l'Institut national de la Recherche scientifique du Rwanda. Les ajustements à la fonction béta ont été réalisés sur l'ordinateur IBM 1130 de la Faculté des Sciences agronomiques de l'Etat à Gembloux; nous remercions vivement le Dr. J. Rondeux pour sa collaboration dans la réalisation du programme et des calculs.     

Étude cinétique de l'hypersensibilité de type retardé dans la candidose expérimentale de la souris

Mice were inoculated with different quantities of blastospores ofCandida albicans by subcutaneous or intravenous ways. Delayed hypersensitivity was then studied during the course of infection by means of the inhibition of macrophage spreading test. In the same time retrocultures were done from kidney material, target organs in the experimental candidiasis. The results obtained in this way enabled the authors to think that cellular immunity plays a role in this experimental model as described by Mackaness.

Travail de l'Unité 42 de l'INSERM et du Groupe de Mycologie Fondamentale et Appliquée de LILLE.     

Localisation ultrastructurale de la phosphatase acide et de la phosphatase alcaline dans les cloisons septales stériles de l'anthozoaire Pachycerianthus fimbriatus

Résumé La phosphatase acide et la phosphatase alcaline ont été localisées dans les cellules des cloisons septales stériles d'un Cérianthe. Chez les animaux à jeun, l'activité de la phosphatase acide a été observée dans les citernes de l'appareil de Golgi, les lysosomes et les phagosomes provenant d'un repas précédent. Chez les animaux nourris dans les 12 heures précédentes, le précipité est localisé dans les mêmes structures ainsi que dans des phagosomes récemment formés par l'absorption de proie. La phosphatase alcaline a été détectée sur les membranes plasmiques apicales et latérales et dans les phagosomes anciens.

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Ultrastructural localization of acid and alkaline phosphatases in sterile septae of the anthozoa Pachycerianthus fimbriatus

Summary Acid and alkaline phosphatase activity has been localized in the cells of the sterile septae of starved and fed anthozoa. Acid phosphatase is present in lysosomes, in Golgi cisternae and old phagosomes of starved animals. In fed animals, the reaction is more intense and the number of lysosomes is increased. New phagosomes are loaded with lead phosphate. In starved animals, the alkaline phosphatase activity has been observed on the plasma membranes and in the old phagosomes.

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Ce travail a été rendu possible grâce à une bourse post-doctorale de recherche attribuée au titre des accords France-Québec, (Y.T.) et grâce à un octroi du Conseil des Recherches Médicales du Canada (J.H.)     

Sur l'existence de cellules de type ≪corticotrope≫ dans la pars intermedia de l'hypophyse du rat

Résumé Nos observations démontrent l'existence de deux types de cellules glandulaires dans la pars intermedia de l'hypophyse du rat: des cellules propres, à M.S.H., dont les grains de sécrétion sont détruits par la fixation osmiée et relativement bien conservés par la fixation au glutaraldéhyde; des cellules à petits grains denses, osmio-résistants, qui s'apparentent morphologiquement aux éléments corticotropes de l'antéhypophyse. L'existence bien connue d'A.C.T.H. ou, plus précisément, d'un facteur A.C.T.H.-like dans le lobe neuro-intermédiaire nous fait considérer comme très vraisemblable la nature corticotrope de ce deuxième type cellulaire de la pars intermedia.

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On the existence of cells of the Corticotrophic type in the intermediate lobe of the rat hypophysisAn electronmicroscopic study

Summary Two types of glandular cells have been shown to occur in the intermediate lobe of the rat hypophysis: 1) M.S.H. producing cells whose secretory granules are destroyed by osmium fixation and relatively well preserved by glutaraldehyde fixation, 2) cells with small dense osmium resistant granules being morphologically similar to the corticotrophic cells of the anterior lobe. The well known occurrence of A.C.T.H. or, more precisely, of an A.C.T.H.-like factor in the neuro-intermediate lobe makes the corticotrophic nature of this second cell type very likely.

Travail dédié à la mémoire de Nicole Granboulan.     

Performances de la TEP au 18F-FDG dans la caractérisation initiale de la lésion primitive du cancer du sein

Objective¹⁸F-FDG PET/CT is for the moment not recommended for stage T of the TNM classification of breast cancer. The aim of our study was to evaluate the performance of ¹⁸F-FDG PET/CT in the initial staging of breast tumors. Tumor size, skin involvement and inflammation as well as the relationship between primary tumor maximum standardized uptake value (SUVmax) and histopathological grade (SBR), molecular tumor subtypes (luminal A and B, Her2 enriched, triple negative), estrogen receptors (ER), progesterone receptors (PR) and focality were evaluated.MethodsHistological reports of patients operated for breast cancer, without neoadjuvant chemotherapy, were compared to preoperative ¹⁸F-FDG PET/CT.ResultsSeventy-four patients who underwent surgery in 2016 were included. ¹⁸F-FDG PET/CT was able to visualize primary tumors in 91% and to correctly classify the T stage of the TNM classification in 81% of the cases, to detect multifocality in 73% and cutaneous and inflammatory breast cancers in 100%. The uptake intensity of ¹⁸F-FDG (SUVmax) was significantly correlated with histo-prognostic factors such as SBR grade (P = 0.02), lack of expression of estrogen receptors (ER) (P = 0.01) and progesterone (PR) (P = 0.02), positive HER2 status (P = 0.01) or triple negative subtype tumors (P = 0.02).Conclusion¹⁸F-FDG PET/CT provides relevant elements for local assessment, in particular, tumor focality and inflammatory character in addition to ensuring the regional and extension assessment.     

La cognition dans le trouble obsessionnel compulsif : à l’intersection de la clinique et de la neuro-imagerie

The investigation of neural activity in OCD (Obsessive Compulsive Disorder) has allowed to link obsessive compulsive symptoms and cortico-striatal dysfunction. In the present article, we try to show the significance of cognition in an integrative physiopathologic model of OCD. Clinically, patients are unable to inhibit irrelevant thoughts or actions. In a cognitive way, decision making, planification or organisation are impaired. Those impairments are related to an executive deficit, which depends on frontal structures. Finally, we present a current study which tries to identify executive deficit functions related to cerebral dysfunction in patients presenting different OCD features (washing, checking, hoarding).