Anticorps anti-spermatozoïdes: Revue de la littérature

Auto immune infertility represents about 15% of all sterilities. The most commun mechanisms of autoimmunity in males are genitals infections (epidymitis) and traumatisms (vasectomies, testiculat biopsies). Mixt agglutination reaction test and immunobead test are the most commun tests used for detection of antibodies. Since 1981, researchs tried to characterize spermatozoa antigens by using polyclonal and monoclonal antibodies. More than 30 antigens had been found during this last decade. Naz and coll had identified an antigen called FA 1 antigen. FA 1 Ag is a 23 Kd glycoprotein. Anti FA1 antibodies inhibit binding and penetration of sperm to zona intact mice oocytes and also zona free hamster oocytes. They do so without causing agglutination or immobilization of sperm and by the way they cannot be detected by usual tests.     

Perspectives de l’analyse de la mobilité des spermatozoïdes

Several studies have shown a good correlation between sperm motility and fertility though the microscopic evaluation of the percentage of motile sperm is highly subjective by nature. Therefore in the last decade, various objectives methods have been proposed to overcome this problem. Two types of methods were developed: The methods based on the analysis of images obtained by microphotography, microcinematography and microvideography and the global, undirect methods based on physical principles. Several systems based on video and image analysis (Computer Aided Sperm Analysis, CASA) have been developed and are used in numerous laboratories of reproductive biology. CASA technology offers the possibility to analyse some characteristics of sperm motion which are related to the fertilization potential and to develop new parameters related to some important aspects of sperm behavior such as hyperactivation. However, there is a large amount of interactions between the operator and the CASA machine. CASA instruments are not “ready-to-use” robots: the reliability of CASA depends largely on the expertise and training of the user and the application of standardized procedures and quality control schemes. By contrast, there is only minimal interaction between the operator and the Sperm Quality Anlyser which is a new device measuring and index of sperm motility highly correlated to the concentration of progressively motile sperm. The device uses light passed through a small sample of semen introduced in a capillary tube to detect variations in optical density that result from moving particles. The reproducibility of the measurements is excellent, the device is easy to use and this is a potentially useful tool for field-work studies. Further investigations of this device in the managment of male infertility is warranted. Finally, both types of objectives approaches are complementary to the conventional analysis of sperm motility and they will not replace it. Standardized procedures have been proposed by the World Health Organization for the subjective evaluation of sperm motility. Such procedures are very useful to reduce significantly the intra- and interlaboratory variations but internal and external quality controls schemes indicate that they are not sufficient to achieve acceptable levels of variation and regular quality controls followed by the definition and the application of corrective procedures are required.     

Évolution de la composante lipidique de la membrane plasmique des spermatozoïdes durant la maturation épididymaire

One aspect of mammalian post-testicular sperm maturation is the progressive change in their plasma membrane lipid composition. These modifications in lipids allow sperm cells to fuse with oocytes during fertilization. A significant share of these sperm lipid changes occurs during their descent through the epididymal tubule. It then continues within the female genital tract during the capacitation process, an essential prerequisite for acrosomic reaction and hence fertilization. This review presents what is known concerning the sperm plasma membrane lipid changes during epididymal maturation in various mammalian models. In the first section, after a brief presentation of the classic eukaryotic cell plasma membrane lipid organization, the emphasis is on the particularities of sperm plasma membrane lipids. The second section presents the different changes occurring in the three major classes of lipids (i.e. phospholipids, sterols and fatty acids) during the sperm’s epididymal descent. The final section briefly describes the mechanisms by which these lipid changes might happen in the epididymal lumen environment. The role played by lipid-rich vesicles secreted by the epididymal epithelium via apocrine secretory processes is highlighted.     

Controle de la multiplication et de la polyploïdie des hepatocytes du rat

Résumé L'injection de substances irritantes de nature chimique variée perturbe les mécanismes qui contrÔlent la multiplication des hépatocytes du rat.Les très jeunes rats réagissent de faÇon intense et reproductible. 15 heures après l'injection il se produit une augmentation brève et intense du nombre des cellules entrant en phase S de sorte que les divisions cellulaires, qui normalement auraient été réparties sur les 30 ou 40 prochaines heures, débutent en l'espace de 2 heures seulement. La croissance hépatique a pris une importante avance qui est suivie par une période de diminution du nombre des mitoses due à une rétroaction inhibitrice.La réaction des rats plus âgés met en évidence un mécanisme inhibiteur permanent qui entraÎne une réponse moins intense et moins régulière.La production d'hépatocytes binucléés et polyploÏdes parait liée à ce mécanisme inhibiteur.La régularité et la sensibilité des réactions des très jeunes rats en fait un matériel de choix pour l'étude des mécanismes régulateurs de la croissance hépatique.

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Control of multiplication and polyploidy of rat hepatocytesA study of the perturbations of physiological regulation induced by injection of irritants

Summary The injection of irritating substances of various chemical nature disturbs the mechanisms regulating the multiplication of rat hepatocytes.The reaction of baby rats is intense and reproducible. It results, 15 hours after the injection, in an increase of the number of cells entering the S phase, so that practically all the divisions which would normally have been scattered over 36 hours are initiated within 2 hours. This burst of synchronized mitosis corresponding to a 36 hours advance in the hepatic growth is followed by a decrease of mitoses due to a feed-back inhibition.The reaction of older rats brings to evidence a permanent inhibitory mechanism that results in a less regular and intensive response.The production of binucleated and polyploÏd hepatocytes seems to be correlated to this inhibitory mechanism.The regularity and sensivity of the baby rat reactions make them a choice material for the study of hepatic growth.

     

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.     

Alcaloïdes de Pandaca retusa

The alkaloidal content of the leaves and trunk bark of Pandaca retusa (Lmk) Mgf. has been studied. All the alkaloids isolated belong to the ‘Iboga’ group of indole alkaloids. These results are discussed in relation with the chemotaxonomy of the genus Pandaca.     

Alcaloïdes de Rauwolfia suaveolens

Nine alkaloids were isolated from Rauwolfia suaveolens S. Moore. Four of them are new: suaveoline, norajmaline plus an hydroxyyohimbine and a methoxyheteroyohimbine. The five others are known: ajmaline, tétraphyllicine, normacusine-B, lochnerine and polyneuridine.     

En France, la majorité des donneurs de spermatozoïdes souhaite le maintien de leur anonymat

So far in France, sperm donor anonymity, which was a fundamental principle and has been twice confirmed in the law in 1994 and 2004, is debated nowadays. In this context, the Cecos wanted to know the donors opinion on anonymity. In 2006, 193 semen donors recruited in 14 Cecos answered anonymously a questionnaire: 73% were in agreement with the principle of anonymity and less than 30% agreed that the future law should change to allow the children to know the donor identity. In case of anonymity disclosure, 60% would give up their sperm donation. The same proportion of donors would accept that non identifying information on them could be given on request to the parents and the child.     

Alcaloïdes des feuilles de Voacanga thouarsii

Leaves of Voacanga thouarsii Roem. et Schult. yielded 3 indole alkaloids (ibogaine, voacangine, voacristine) and 12 ‘bis-indole’ alkaloids. Three of the latter are known (vobtusine, vobtusinelactone and subsessiline) and nine are new.     

Alcaloïdes des feuilles de Holarrhena febrifuga

Leaves of Holarrhena febrifuga from East Africa contain 1·5% of alkaloids, mostly of the amino-3α ceto-20 pregnane-5α type. Six alkaloids have been isolated: funtumine (I), holamine (II), dimethyl- and monomethyl-funtumine (Ia) and (Ib), dimethyl- and monomethylholamine (IIa) and (IIb); these methyl derivatives have been isolated for the first time from natural source. Pregnane-3,20-dione has been isolated from the same leaves.