Electromagnetic characterization of PCB cards for mobile phones

International audienceIn this article we focus on the EMC characterization of PCB cards for mobile phones especially the filtering part in order to position the best way the components on the routing. To be precise, all the electrical characteristics of the cabling including the inductive couplings have to be taken into consideration. To achieve this modeling, the PEEC method (partial element equivalent circuit) has been used to obtain an electrical equivalent circuit of the connections of the PCB structure. This model takes into account all the parasitic elements. A study of the transfer function of the filter can be obtained and Spice-like simulations can give the waveforms of current and voltage in time domain. Moreover, solving the circuit equations on the global electrical model, the current distribution in the PCB tracks can be drawn and “hot” points can then been identified. Several configurations of a PCB card for mobile phone have been studied according the value of some geometrical parameters or the position of passive component on the PCB

Freezability of chicken immature germ cells in their seminiferous tubules

International audienc

The use of an insulin sensitizer has delayed the spermatogenesis

International audienc

Progressive acquisition of sperm storage potential in the chicken oviduct

National audienc

Effet de la metformine sur la fonction testiculaire chez le poulet

National audienc

Use an avian cell culture model to analyze effects of endocrine disruptors on the testicular tissue

International audienceIn recent decades, many tests in vivo or in vitro models mainly based on mammalian (rat-mouse) and fish were used to assess the risks raised by contact or ingestion of molecules with an pharmaceutical, agricultural or natural origin. But, none or few in vitro tests using bird models have been explored despite their advantages: the embryonic gonads of birds have a high plasticity of development, and sperm production is nearly two times faster than in rodents. Thus, birds present one gonad in female and two gonads in male. In the presence of estrogenic substances or antagonist of estrogen production, during the first days of the embryonic life, the sex gonadic phenotype could change. Hence, as part of a national project (post-Grenelle Environment Forum), we have established the in vitro culture of germ cells and somatic cells from chicken testis and we have evaluated the sensitivity against two molecules known to be endocrine disruptors: phtalates (mono-(2-ethylhexyl) phthalate, MEHP) and ethinyl estradiol (EE2) in comparison to previous studies using rodent and human system. After 96 h of culture in presence of 10μM MEHP, cultures present a structural alteration, a reduction in cell proliferation and in germ cells population. These results are in accordance with previous studies using rat, mice or humans culture of testicular cells and with similar sensitivity levels or even better sensitivity for some 'end-points' (biological parameters). Moreover, we observed an increase in proliferative germ cells and a decrease in apoptosis or oxydative stress starting at the lower EE2 dosis (0.03 ng/ml, output value of wastewater) to 300 ng/ml. These cells preparations were also able to be frozen and thawed for a latter use, because VASA-positive germ cells were detected after 96h of culture. In conclusion, the establishment of this testicular cells culture could be considered as an in vitro alternative method, complementary to mammals model, limiting the number of animals used and with an elevated sensitivity at least for these two endocrine disruptors

Effect of metformin on the fertilizing ability of mouse spermatozoa

Numerous antioxidants have been added to cryopreservation media with varied success. The biguanide, metformin, commonly used for the treatment of type II diabetes, possesses properties impacting metabolism control that have not been yet assessed in cryopreservation protocols. The aim of this experiment was to; (i) determine the effect of metformin on fresh spermatozoa properties; and (ii) to assess positive or negative effects of metformin in post-thaw function and fertilizing capacity of mouse spermatozoa when used in cryopreservation media. The experiments have shown that the presence of metformin in fresh semen did not induce negative effects on spermatozoa quality, except a slight reduction in sperm motility at 5000μM metformin. However, when metformin was included in a cryopreservation protocol, an improvement in the fertilization rate and a reduction in the percentage of abnormal zygotes after in vitro fertilization was observed. In conclusion, metformin did not affect sperm quality at low concentrations (50μM), but its presence in the cryopreservation media could represent a benefit to improve the quality of frozen semen

Administration de metformine au cours de la gestation : conséquences sur l'appareil reproducteur des souriceaux mâles

National audienc

Développement d'outils de diagnostic en reprotoxicologie aviaire

National audienc

Characterization of chicken Sertoli cells in vitro

In the testis, Sertoli cells play a key physiological role in that they support, nourish, and protect germ cells. Because of the importance of Sertoli cells, several laboratories have established a culture system of Sertoli cells. These cultures have been well developed in mammalian species, but to our knowledge no purified avian Sertoli cells culture has been described. The aim of this study was to isolate avian Sertoli cells and to investigate their function using a chicken model in an in vitro test system. Immature chicken Sertoli cells in culture present morphology similar to that of mammalian cells and conserve expression of the specific Sertoli marker, anti-Mullerian hormone. Furthermore, in contrast to mammals, they express the 3 beta-hydroxysteroid dehydrogenase enzyme. Stimulation of Sertoli cells with ovine follicle-stimulating hormone rapidly activates the 3 main downstream signaling pathways of the follicle-stimulating hormone receptor: cyclic adenosine monophosphate/protein kinase A, phosphatidylinositol 3-kinase/Akt, and mitogen-activated protein kinase pathways. In vitro, Sertoli cells are able to secrete lactate and inhibin and have conserved the phagocytosis property. Finally, avian Sertoli cells present 3 interesting characteristics: they actively proliferate in vitro, can be passaged several times, and are suitable for freezing in nitrogen. A direct consequence of these properties is to use this cell culture test system as an alternative method to bird reprotoxicity studies