Despite their roles in intercellular communications, the different populations of extracellular vesicles (EVs) and their secretion mechanisms are not fully characterized: how and to what extent EVs form as intraluminal vesicles of endocytic compartments (exosomes), or at the plasma membrane (PM) (ectosomes) remains unclear. Here we follow intracellular trafficking of the EV markers CD9 and CD63 from the endoplasmic reticulum to their residency compartment, respectively PM and late endosomes. We observe transient co-localization at both places, before they finally segregate. CD9 and a mutant CD63 stabilized at the PM are more abundantly released in EVs than CD63. Thus, in HeLa cells, ectosomes are more prominent than exosomes. By comparative proteomic analysis and differential response to neutralization of endosomal pH, we identify a few surface proteins likely specific of either exosomes (LAMP1) or ectosomes (BSG, SLC3A2). Our work sets the path for molecular and functional discrimination of exosomes and small ectosomes in any cell type.

Artículo de publicación ISIThis paper presents an empirical analysis of the socioeconomic status (SES) school segregation in Chile, whose educational system is regarded as an extreme case of a market-oriented education. The study estimated the magnitude and evolution of the SES segregation of schools at both national and local levels, and it studied the relationship between some local educational market dynamics and the observed magnitude of SES school segregation at municipal level. The main findings were: first, the magnitude of the SES segregation of both low- SES and high-SES students in Chile was very high (Duncan Index ranged from 0.50 to 0.60 in 2008); second, during the last decade, SES school segregation tended to slightly increase in Chile, especially in high schools (both public and private schools); third, private schools – including voucher schools – were more segregated than public schools for both low-SES and high-SES students; and finally, some market dynamics operating in the Chilean education (like privatization, school choice, and fee-paying) accounted for a relevant proportion of the observed variation in SES school segregation at municipal level. These findings are analyzed from an educational policy perspective in which the link between SES school segregation and market-oriented mechanisms in education plays a fundamental role

Protein tyrosine phosphorylation is an important intracellular event accompanying the in-vitro capacitation of mouse, bovine and human spermatozoa. Here, we demonstrate that bovine serum albumin (BSA) and NaHCO(3) are required for protein tyrosine phosphorylation in ejaculated human spermatozoa. The absence of protein tyrosine phosphorylation in media minus these two constituents could be recovered by addition to the media of cAMP analogues and/or phosphodiesterase inhibitors. Since BSA is postulated to modulate capacitation by removal of cholesterol from the sperm plasma membrane, we determined whether cholesterol release leads to changes in protein tyrosine phosphorylation. Incubation of spermatozoa in media containing BSA resulted in the release of significant amounts of cholesterol when compared with media devoid of BSA. Preloading BSA with cholesterol-SO(4) inhibited protein tyrosine phosphorylation, as well as capacitation, and this inhibitory effect was overcome by the addition of dibutyryl cAMP plus isobutylmethylxanthine (IBMX). The functional significance of BSA-mediated cholesterol release, protein tyrosine phosphorylation and capacitation was confirmed by examining the effects of the cholesterol-binding heptasaccharides, methyl-beta-cyclodextrin or OH-propyl-beta-cyclodextrin. Both cyclodextrins caused cholesterol efflux from the spermatozoa, increased protein tyrosine phosphorylation, and stimulated capacitation. Therefore, cholesterol release is associated with the activation of a signal transduction pathway involving protein kinase A and tyrosine kinase second messenger systems, and resulting in protein tyrosine phosphorylation and capacitation.

Sperm capacitation in vitro is highly correlated with an increase in protein tyrosine phosphorylation that is regulated by cAMP through a unique mode of signal transduction cross-talk. The activation of this signaling pathway, as well as capacitation, requires bovine serum albumin (BSA) in the incubation medium. BSA is hypothesized to modulate capacitation through its ability to remove cholesterol from the sperm plasma membrane. Here we demonstrate that the cholesterol-binding heptasaccharides, methyl-␤-cyclodextrin and OH-propyl-␤-cyclodextrin, promote the release of cholesterol from the mouse sperm plasma membrane in media devoid of BSA. Both of these ␤-cyclodextrins were also demonstrated to increase protein tyrosine phosphorylation in the absence of BSA in both mouse and bull sperm, and the patterns of phosphorylation were similar to those induced by media containing BSA. The potency of the different ␤-cyclodextrins to increase protein tyrosine phosphorylation in sperm was correlated with their cholesterol binding efficiencies, and preincubation of the ␤-cyclodextrins with cholesterol-SO 4 Ϫ to saturate their cholesterol-binding sites blocked the ability of these compounds to stimulate protein tyrosine phosphorylation. The ␤-cyclodextrin effect on protein tyrosine phosphorylation was both NaHCO 3 and protein kinase A-dependent. The ␤-cyclodextrins were also able to capacitate mouse sperm in the absence of BSA, as measured by the ability of the zona pellucida to induce the acrosome reaction and by successful fertilization in vitro. In summary, ␤-cyclodextrins can completely replace BSA in media to support signal transduction leading to capacitation. These data further support the coupling of cholesterol efflux to the activation of membrane and transmembrane signaling events leading to the activation of a unique signaling pathway involving the cross-talk between cAMP and tyrosine kinase second messenger systems, thus defining a new mode of cellular signal transduction initiated by cholesterol release.

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BackgroundSexual risk behaviors associated with poor information on sexuality have contributed to major public health problems in the area of sexual and reproductive health in teenagers and young adults in Colombia.ObjectiveTo report our experience with the use of DoctorChat Mobile to provide sexual education and information among university students in Bogota, Colombia, and knowledge about the sexual risk factors detected among them.MethodsA mobile app that allows patients to ask about sexual and reproductive health issues was developed. Sexual and reproductive risk behaviors in a sample of young adults were measured before and after the use of the app through the validated survey Family Health International (FHI) Behavioral Surveillance Survey (BSS) for Use With Adults Between 15 and 49 Years. A nonprobabilistic convenience recruitment was undertaken through the study´s webpage. After completing the first survey, participants were allowed to download and use the app for a 6-month period (intervention), followed by completion of the same survey once again. For the inferential analysis, data was divided into 3 groups (dichotomous data, discrete quantitative data, and ordinal data) to compare the results of the questions between the first and the second survey. The study was carried out with a sample of university students between 18 and 29 years with access to mobile phones. Participation in the study was voluntary and anonymous.ResultsA total of 257 subjects met the selection criteria. The preintervention survey was answered by 232 subjects, and 127 of them fully answered the postintervention survey. In total, 54.3% (69/127) of the subjects completed the survey but did not use the app, leaving an effective population of 58 subjects for analysis. Of these subjects, 53% (31/58) were women and 47% (27/58) were men. The mean age was 21 years, ranging between 18 and 29 years. The differences between the answers from both surveys were not statistically significant. The main sexual risk behaviors identified in the population were homosexual intercourse, nonuse of condoms, sexual intercourse with nonregular and commercial partners, the use of psychoactive substances, and lack of knowledge on symptoms of sexually transmitted diseases and HIV transmission.ConclusionsAlthough there were no differences between the pre- and postintervention results, the study revealed different risk behaviors among the participating subjects. These findings highlight the importance of promoting high-impact educational strategies on this matter and the importance of providing teenagers and young adults with easily accessible tools with reliable health information, regardless of their socioeconomic status.

We conducted a telephone survey of all patients referred to a realtime telemedicine consultation at the Centre for Telehealth in Bogotá. Over a six-month period, 281 teleconsultations were conducted, and we were able to retrieve telephone numbers for 156 patients. Of these, 121 patients (78%) agreed to answer the questionnaire. Eighty percent of the respondents were satisfied or very satisfied with the teleconsultation and 63% would use telemedicine again. Sixty-five percent thought that telemedicine improved their medical care. More than 50% believed that telemedicine had a positive effect in terms of medical care improvement, time- and cost-savings. Twenty-seven percent felt that teleconsultation was not as good as a traditional face-to-face consultation. Lack of familiarity with ICT did not appear to act as a major barrier to telemedicine, and cognitive factors may be more important in acceptability to patients and their satisfaction. The results of the present study may also be relevant to the poorest countries of the world, where two-thirds of the population live in rural areas.

The co-expression of alpha1beta1, alpha4beta1 and alphavbeta3 integrins in the human endometrium coincides with the implantation window. The alphavbeta3 integrin is expressed in the apical surface of the luminal epithelium and may serve to anchor trophoblast cells in the adhesion phase of implantation. Using immunohistochemistry, we compared the expression of alphav, alpha1, alpha4 and beta3 integrin subunits in samples of normal human Fallopian tube and endometrium obtained from five women in the non-receptive period (luteal phase days 2-4) and from another five women in the receptive period (luteal phase days 6-8). The staining was quantified visually on a scale of 0 to ++, according to the intensity and density of stained cells. The alphav subunit is expressed in the Fallopian tube epithelium during both periods in a pericellular distribution. The beta3 subunit is also expressed in the same location, but it is up-regulated during the period of endometrial receptivity. The other subunits are expressed in localizations which are not relevant to trophoblast adhesion and exhibit little or no difference in the level of expression between the non-receptive and receptive periods. Based on these results we postulate that the expression of the beta3 subunit in the human tubal epithelium is under the same systemic controlling signals as in the endometrium and that the normal tubal epithelium may have an implantation window, at about the same time as the endometrium, that affords the opportunity for trophoblast attachment should a 5-7 day embryo be unduly retained in the tube.