Lytic to temperate switching of viral communities.

Microbial viruses can control host abundances via density-dependent lytic predator-prey dynamics. Less clear is how temperate viruses, which coexist and replicate with their host, influence microbial communities. Here we show that virus-like particles are relatively less abundant at high host densities. This suggests suppressed lysis where established models predict lytic dynamics are favoured. Meta-analysis of published viral and microbial densities showed that this trend was widespread in diverse ecosystems ranging from soil to freshwater to human lungs. Experimental manipulations showed viral densities more consistent with temperate than lytic life cycles at increasing microbial abundance. An analysis of 24 coral reef viromes showed a relative increase in the abundance of hallmark genes encoded by temperate viruses with increased microbial abundance. Based on these four lines of evidence, we propose the Piggyback-the-Winner model wherein temperate dynamics become increasingly important in ecosystems with high microbial densities; thus 'more microbes, fewer viruses'.

[Participation of growth factors in human reproduction]. / Participación de los factores de crecimiento en la reproducción humana.

The Growth Factors (GFs) include a group peptidic molecules, with important trophic, mitotic and cellular differentiation effects in most human tissues. This review encompasses the different types of GFs and their biologic effects on tissues involved in the human reproductive process. The importance of the GF in the embryonic development and the implantation process is also commented. Finally, we assess the participation of the GFs in the pathophysiology of the Polycystic Ovary Syndrome and Endometriosis based on recent investigations. The review permit us appreciate the importance of the GFs as mediators of different hormones (in their secretion and biological effects) and in the regulation of some cellular events. The real value of these GFs in the daily clinical practice is as yet to be established, due to the technical laboratory limitations with respect to their identification and quantification, as well as the lack of more clinical research in humans. The GFs are promising molecules for the treatment of infertiles couples and for the application of the technics of assisted reproduction, in vivo and in vitro.

[Current state of conservative management of ectopic pregnancy]. / Estado actual del manejo conservador del embarazo ectópico.

The ectopic pregnancy constitutes a disease that require the most diagnostic accuracy, not only for the biologic importance of its clinical manifestations, but for the sequelae of its treatment too, in relation with the fertility of a patient frequently affected with infertility so far. The increase in its frequency, by multiple factors, including treatment of infertility itself and Assisted Reproduction techniques, make the clinician must be alert and have availability of all diagnostic tools for the establishment of an oportune and conservative treatment, directed to prevent an acute alteration of the hemostasis and a shadowy reproductive future. The present review of the literature about the conservative management of the ectopic pregnancy let us have to know the criteria neccessary for giving the optimum treatment to our patients and offering them a better reproductive future.