Anticorps anti-spermatozoïdes: techniques de dépistage et interprétation des résultats

Since the first publication on the detection of sperm-agglutinating antibodies in infertile men, multiple assays have been described. The most useful tests are able to detect antibodies bound to the sperm membrane of motile spermatozoa. The immunobeads test (IBT) is considered to be the most advantageous in terms of its sensitivity, the low incidence of false-positive results, and its ability to localize antibodies of different immunoglobulin classes on the sperm surface. The IBT assay can be used in parallel with the mixed antiglobulin reaction (MAR), to detect sperm-associated antibodies in the ejaculates of infertile men, the most rational way to test for antisperm antibodies (ASA) in males. In view of the high level of agreement between the two assays, MAR, the easier of the two, may be used as a first step in the detection of these antibodies. A positive MAR must be confirmed by IBT, as this assay is more specific for the detection of IgA antibodies. The clinical significance of sperm-associated antibodies is usually established according to the proportion of motile spermatozoa coated with immunobeads, its class and its localization on the sperm surface. However, binding of immunobeads does not provide any information about the antigens against which the antibodies are directed. As the functional effects of sperm-associated antibodies may vary as a function of their antigenic specificities, other assays, using purified fertilization related antigens, are necessary to establish, for each individual, the specific impact of the antibodies on the fertilization process. The indirect IBT assay has recently become the most widely used test to detect the various classes of ASA in serum and cervical mucus of infertile women and in the serum and seminal fluid of infertile men, in combination with the direct assay described above. However, in most laboratories, it is performed with only one dilution of the biological fluid tested, usually a low dilution, so that antibody levels of no significance for fertility could be detected. This may explain a recente debate (Human Reprod, 1999) on the significance of ASA as a cause of infertility. At present, and in the absence of standardized assays able to identify the antigens involved in each individual immune reaction, antibody assays, as detected by the IBT assay, in the serum and/or genital secretions of infertile subjects might provide useful clinical guidance.     

Comparaison de quatre méthodes d’évaluation des modifications de la perfusion cérébrale en tomoscintigraphie

IntroductionWe compared four different methods to assess changes in cerebral blood flow in patients with normal pressure hydrocephalus using cerebral ECD SPECT before and after injection of acetazolamide.Material and methodsEleven patients underwent cerebral SPECT before and after injection of 1 g of acetazolamide using a ^99mTc-ECD split-dose protocole with a first injection of 370 MBq and a second of 1100 MBq. After reconstruction of volumes with Neurogam^® (Segami) software, we compared visual analysis to semi quantitative analysis provided by Neurogam software, ratios methods and parametric analysis under SPM99 and SPM2.ResultsVisual analysis is immediate but frequently misleading. The contribution of Neurogam depends on the reader's skill and may be significant for non expert readers. The manual semi-automatic method is tedious and its results depend on the choice of the areas of interest and reference necessary for activity normalization. At last, the automatic method carried out by SPM is reliable for population analysis, but its efficiency for individual analysis remains to be evaluated.     

18FDG et radiothérapie externe,le point de vue du radiothérapeute.: Application des techniques de fusion d’images à la radiothérapie des carcinomes bronchiques

The prognosis of patients with localized non-small-cell lung carcinoma and treated with radiation therapy remains poor. The three-dimensional conformational radiotherapy aims to increase the dose of radiation at the tumor volume to increase the local control, while sparing the healthy tissue neighborhood. The reduction of the safety margins and the irradiated volumes obliges to determine with most acute precision the exact tumor volume. However, the scanner alone is insufficient, particularly at the mediastinal level and at a distance. The positron emission tomography allows distinguishing a biological tumor volume. It helps to define the lung tumor volume, especially when the tumor is accompanied by atelectasis, and to recover the lymph node staging at the mediastinal level and at a distance. Even if the sensibility and the specificity are not 100 %, positron emission tomography now becomes essential before considering an escalation of thoracic radiation dose.     

Le cycle de développement des Castes chezReticulitermes

Résumé La production des castes, notamment des nymphes, futurs imagos ailés et des ouvriers chez leReticulitermes lucifugus est soumise à un cycle biologique annuel. L'auteur montre que dans les colonies naturelles les nymphes apparaissent quelques semaines après l'essaimage des jeunes imagos, vers la fin du printemps en une fois et en grande quantité. Elles se développent pendant l'été et arrivent en automne à l'avant-dernier ou même au dernier stade avant la mue imaginale. En hiver le développement de la colonie est normalement arrêté par le froid. Au début du printemps les nymphes se transforment en imagos et quittent la colonie. Pendant le repos hivernal les sexuées femelles accumulent beaucoup de corps gras et, au moment où les grandes nymphes se transforment en imagos, une ponte massive se produit dans le nid. Après la disparition des imagos la colonie voit son potentiel nutritif considérablement augmenté, puisqu'il n'y a plus de nymphes à nourrir. Pour cette raison les larves, à leur tour bien alimentées, peuvent se transformer en nymphes. Celles-ci, par leur croissance et leur constant besoin de nourriture, abaissent de nouveau le potentiel alimentaire. En conséquence de cette baisse, les larves qui apparaissent pendant l'été et l'automne sont mal nourries et donnent des ouvriers.Si les colonies deReticulitermes l. santonensis ont leur nid dans une maison bien chauffée en hiver, comme c'est le cas dans quelques immeubles de La Rochelle, lecycle annuel peut se transformer encycle semestriel. Les nymphes formées au printemps arrivent à l'état imaginal en automne et essaiment alors. Quand ils quittent la colonie un nouveau cycle commence qui permet un autre essaimage cinq à six mois plus tard, au printemps.L'auteur suppose que le facteur climatique et le facteur alimentaire jouent le rôle principal dans la formation des nymphes et dans le cycle biologique des Termitières.     

Développement et évaluation d’un algorithme de segmentation automatisée des ventricules gauche et droit sur des images ciné d’IRM

An automated segmentation of the left and right ventricles on cine MRI is presented here. A rectangular region around the object of interest is defined in the original image, a morphological filter is then applied that combines openings and closings on connected sets, providing an image with homogeneous regions, which is finally segmented with an active contour model. The algorithm was tested on two databases with an expert's segmentation on the ventricles. One of the databases was provided by the Multicentric Initiative for a Platform of Evaluation in Cardiac Imaging (IMPEIC) group. Results show a very satisfactory correlation between the area (given in mm²) of expertise (x) and the area of automated segmentation (y) of the left ventricle (y = 1.00x + 8.6, r = 0.99). First results on the right ventricle show more than 83% similarity. The systolic phase proved to be more difficult to segment, which could be taken into consideration by introducing time regularization criteria in the algorithm.     

Intérêt potentiel des images paramétriques des temps d’éjection et de relaxation en tomoscintigraphie des cavités cardiaques dans l’évaluation des cardiopathies asynchrones

Intraleft dyssynchrony is strongly correlated to contractile dysfunction associated to severe heart failure. Dyssynchrony is also a predictive marker for cardiac resynchronization therapy response. We measured dyssynchrony values for both ventricles from gated blood pool SPECT images.Material and methodsThree groups of patients were sampled from normal patients (n = 7), mild heart failure patients (n = 24) and severe heart failure patients (n = 9). Time-derivative parametric images were obtained from 24-time bins gated blood pool SPECT data. We measured intraleft and interventricular contractile and relaxing dyssynchrony values from these images.ResultsIntraleft dispersions values linked to ventricular peak emptying rate were 107 ± 21 ms, 141 ± 58 ms and 515 ± 104 ms for each of the three groups. The values linked to left ventricular peak filling rate were 122 ± 62 ms, 219 ± 117 ms and 603 ± 164 ms respectively. Statistical significant differences (p < 0.01) were observed both for contractile and relaxing phases for severe heart failure patients. Mild heart failure patients had isolated statistical significant (p < 0.01) alterations of the ventricular relaxing phase. Correlation between isotopic dyssynchrony values and left ejection fraction led to a R square coefficient of 0.71 and 0.64 for time to peak emptying and to peak filling respectively. Correlation to QRS width values led to a R square coefficient of 0.76 and 0.62 respectively.ConclusionVentricular dyssynchrony correlated to the importance of the ventricular mechanical dysfunctions is a robust predictor of heart failure. Separate analysis of contractile and relaxing dyssynchrony may lead to a better understanding and characterization of the mechanical dysfunctions involved in heart failure.     

Intérêt de l’analyse de la morphologie fine et de la qualité nucléaire des spermatozoïdes dans le cadre des techniques d’AMP

Routine semen examination does not identify minor malformations of the sperm nucleus and chromatin architectural defects, which may be associated with ART outcome and cannot be detected by the embryologist even at 1000x magnification. Recent publications have demonstrated the advantages, compared to routine analysis, of a new method of real-time detailed morphological evaluation of motile spermatozoa: motile sperm organellar morphology examination (MSOME). MSOME is performed with an inverted light microscope equipped with high-power differential interference contrast optics enhanced by digital imaging to achieve a magnification of 10000x. To be considered morphologically normal, a sperm nucleus must have both a normal shape and a normal chromatin content. The aim of the present study was to combine MSOME and sperm DNA fragmentation characteristics to assess reproductive outcome. The study population consisted of the male partners of 52 couples referred for conventional IVF or split cycles (half IVF-half ICSI cycles) and exhibiting normal routine sperm parameters. Spermatozoa were analysed by examining the fine nuclear morphology and DNA integrity using the sperm chromatin dispersion test (SCD test), based on the principle that the deproteinized nuclei of spermatozoa with nonfragmented DNA show extended halos of DNA dispersion that are either absent or only minimally present in sperm nuclei with fragmented DNA. Fertilization rates were significantly lower in the group showing less than 8% of normal spermatozoa according to MSOME criteria, but early embryo development was not affected. Fine sperm morphology correlated with DNA fragmentation rate. These results demonstrate that the assessment of sperm nuclear normality by MSOME analysis and SCD test improves characterization of the semen sample and should be evaluated as a tool for allocating patients to specific assisted reproduction treatments.     

Apport des techniques de chromatographie liquide couplée à la spectroscopie de masse tandem aux dosages des stéroïdes

Because of its sensitivity and selectivity, liquid chromatography coupled with tandem mass spectrometry (MS/MS) triple quadrupole is often considered the “gold standard” for quantification of compounds in a complex environment. Its use in clinical laboratory is now extended to the analysis of many steroids. But a biologist before purchasing such equipment must know exactly what he wants to do: is it for identification or quantification of one steroid or steroid group?     

Cinétique de dégradation des hydrocarbures par Candida lipolytica

Résumé Le mécanisme d'assimilation des hydrocarbures par une levure, Candida lipolytica est étudié au moyen de l'analyse cinétique de la croissance du microorganisme et de la disparition du substrat hydrocarboné. Les hydrocarbures utilisés sont des n-paraffines. On ajoute au milieu soit un seul hydrocarbure (n-tetradécane ou n-hexadécane), soit un mélange binaire (n-dodécane et n-heptadécane), soit un mélange complexe (du n-undécane au n-octadécane). Contrairement à d'autres auteurs, nous pensons qu'il est peu probable que l'essentiel de la réaction s'effectue par contact des gouttes de substrat et des microorganismes puisque l'on observe des retards d'assimilation de certains hydrocarbures: ceux de faible poids moléculaire (les plus solubles) sont assimilés plus rapidement. Il semble donc que l'assimilation se fasse en grande partie à partir d'hydrocarbures préablement solubilisés.

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Kinetics of hydrocarbon assimilation by Candida lipolytica

Summary The mechanism of hydrocarbon uptake by a yeast, Candida lipolytica has been studied by means of the kinetic analysis of micro-organism growth and substrate assimilation. Hydrocarbons used as only source of carbon are normal alkanes either pure (n-tetradecane or n-hexadecane) or in mixture of two paraffins (n-dodecane and n-heptadecane) or eight paraffins (n-undecane to n-octadecane). In these last cases delays in n-alkanes consumption are observed. They show that the most soluble substrates (lower molecular weight) are first consumed. In opposition to other authors we think that there is little probability for main reaction occurring by direct contact between drops and micro-organisms. The evidence indicates that n-alkanes are mainly utilized in the dissolved state.

     

Hybridation des acides déoxyribonucléiques de certaines bactéries marines vibrioïdes

The genotypic relationships established by DNA/DNA hybridization in vitro confirm the results obtained by earlier phenotypic analyses of certain vibrio-like marine bacteria. These strains are closely related to the species Photobacterium fischeri, and do not belong to the genus Vibrio. The group of marine, vibrio-like bacteria that require Na⁺ for growth is genotypically very heterogeneous.     

Le comportement de découpage des feuilles chezAtta sexdens

Résumé Comme démarche préliminaire à une étude expérimentale du comportement del'Atta sexdens rubropilosa, nous avons mesuré la quantité de découpage journalier des feuilles fournies à cinq colonies différentes, la quantité de découpage par période de douze heures et, la quantité de découpage de différents végétaux. D'autre part, nous avons introduit différents obstacles dans le circuit qui va des feuilles à l'intérieur du nid.Quant au découpage, nous avons décelé de grosses différences entre les colonies, mais des différences journalières dans chaque colonie. Nous n'avons pu trouver ni un rythme nyctéméral indépendant des conditions extérieures, ni une préférence constante pour un des végétaux fournis. L'introduction des obstacles montre la grande élasticité de ce comportement, aussi bien que sa subordination à la possibilité de livraison des découpures dans l'intérieur du nid.

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Summary This paper is presented as a preliminary inquiring into the leaf-cutting behaviour of the fungus-antAtta sexdens rubropilosa. We have measured the amount of daily leaf-cutting in five ant-nests, the amount of leaf-cutting by periods of 12 hours, and the amount of leaf-cutting of different leaf species. We have found great differences of leaf-cutting between ant-nests and irregular daily differences in each nest. We were unable to find a nycthemeral rhythm independent from environmental conditions, or a preference towards a determined leaf species. Introducing obstacles on the way of leaf-carrying workers showed us a great adaptability of this behaviour, and its subordination to the possibility of introduction of leaf-pieces into the nest.