1,721,026 research outputs found
Determinants of genital shedding of human immunodeficiency virus: A review
No full textSexual transmission is the main route for Human Immunodeficiency Virus (HIV) spreading throughout the world. Heterosexual transmission of HIV is the predominant transmission modality among adults worldwide, while mother-to-child transmission accounts for the majority of HIV infections in children. Factors that affect genital tract shedding of the HIV virus or cell-associated provirus in women are probably important determinants of infectiveness, and hence of transmission risk during sexual contact or delivery. Cervical inflammation and genital ulcers have been associated with HIV shedding in the female genital tract. In fact, both ulcerative sexually transmitted infections (syphilis, chancroid and herpes) and non-ulcerative sexually transmitted infections (gonorrea and chlamydia) have been associated with high rates of transmission and acquisition of HIV. Bacterial vaginosis are associated with an increased prevalence of HIV1-RNA detection in cervicovaginal secretions. Although HIV infection is a well-known risk factor for cervical intraepithelial neoplasia (CIN), the influence of CIN on cervical shedding of HIV is poorly understood. Preliminary data suggest that CIN lesions represent a significant risk factor for genital HIV spreading. Additional factors associated with increased prevalence of HIV1-RNA detection are: advanced stage of the disease, hormonal contraceptive use, cervical ectopy, vitamin A deficiency, cervicitis and vulvovaginal candidiasis. In contrast to the lower female genital tract, the male genital tract is inaccessible to simple direct sampling. Poor detection and quantification of the HIV-1 virus in the semen have largely limited our knowledge of HIV infectivity in men. Symtomatic and asymptomatic urethritis are important cofactors for HIV shedding in the semen, suggesting that local genital tract infection are important determinants of HIV level in semen. Finally, the presence of HIV-RNA in blood strongly correlates with the detection of HIV-related nucleic acids in genital secretions but the shedding of HIV in the genital tract can occur in 20-30% of non-viremic subjects. © 2008 Bentham Science Publishers Ltd
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The cardioprotective paracrine effects exerted by human mesenchymal stem cells are negatively influenced by donor age
No full textBackground: In experimental animal models mesenchymal stem cells (MSC) repair infarcted hearts mainly through paracrine mechanisms. In particular, MSC produce and release anti-apoptotic factors that lead to cytoprotection. For translational purposes, it would be important to verify if human MSC also mediate cardioprotection. In particular, since ischemic heart diseases occur mainly in elderly, it is essential to establish if donor age negatively influences the production of cytoprotective factors. Accordingly, we have compared the paracrine properties of fetal MSC with adult MSC from young and old patients.
Methods: MSC of fetal origin (F-MSC) were isolated from placental amniotic membranes processed immediately after delivery. Adult MSC were collected from bone marrow samples of young (yBM-MSC; donor age 65 years). Rat neonatal cardiomyocytes (H9c2 cells) were used to test cytoprotection. H9c2 cells were exposed to 6 hours of hypoxia followed by 18 hours of reoxygenation in the presence of control medium (CTRL-M) or conditioned medium (CM) from F-MSC (F-CM) or yBM-MSC (Y-CM) or oBM-MSC (O-CM). CM was obtained by growing MSC for 36 hours in the absence of serum. H9c2 viability was measured by MTS assay. The rate of apoptosis was quantified by TUNEL staining. We also evaluated cleaved Caspase 3 using both a colorimetric assay and Western blotting. Gene expression profile of several known cytoprotective factors was assessed by RT-PCR.
Results: The hypoxia/reoxygenation protocol reduced H9c2 viability by 55% compared with basal condition (p<0.001). Both F-CM and Y-CM prevented cell damage compared with CTRL-M resulting in a significant increase in cell viability by 45% (p<0.017) and 33% (p<0.017), respectively. At the contrary, O-CM had no significant effect on H9c2 viability (p=n.s. vs CTRL-M). After the induction of hypoxia/reoxygenation injury, 35 ± 8% of H9c2 cells tested positive for TUNEL staining. Compared with CTRL-M and O-CM, in the presence of F-CM we observed a relative reduction in the number of TUNEL positive nuclei of 91% (p<0.001) and 89% (p<0.001) respectively. The Y-CM also reduced H9c2 apoptotic nuclei (- 67,5% vs CTRL-M, p<0.01; - 64% vs O-CM, p<0.01). In contrast, O-CM did not prevent H9c2 apoptotic death (-11% vs CTRL-M, p=n.s.). The colorimetric assay documented that the F-CM significantly reduce the level of cleaved Caspase 3 by 50% vs CTRL-M (p< 0.017) and by 42% vs Y-CM (p< 0.017); furthermore, the Y-CM reduced the amount of cleaved Caspase 3 by 33% vs O-CM (p< 0.017). Finally, the oBM-MSC-CM did not reduce cleaved Caspase 3 compared with CTRL-M. In the presence of F-CM Western blot analysis confirmed a marked reduction in Caspase 3 activation, while no striking differences were present between CTRL-M, Y-CM and O-CM. The RT-PCR analysis documented that F-MSC express several known cytoprotective factors such as PDGF-β, BMP2, EPO, FGF2 and VEGF at significantly higher level compared with oBM-MSC (p<0.05) and that VEGF, FGF2 and HGF transcripts were significantly higher in yBM-MSC than in oBM-MSC (p<0.05).
Conclusions: We have shown that human MSC can mediate cardiomyocyte protection through the release of soluble anti-apoptotic factors. However, we documented that donor age negatively influences the paracrine cytoprotective properties of adult MSC. Our data suggest that autologous MSC theraphy for ischemic heart disease might be less effective in elderly patients
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
HPV-DNA titres in squamous cervical intrepithelial lesions (SIL): correlation with lesion severity and viral findings
No full textHPV infection and intraepithelial lesions: comparison between HIV positive and negative women.
No full textHuman fetal mesenchymal stem cells protect cardiac myocytes against hypoxia/reoxygenation injury
No full textBackground: Myocardial reperfusion injury represents a major complication of the reperfusive therapies used to treat acute infarction. Consequently, the identification of new cytoprotective strategies able to prevent reperfusion injury is urgently needed. We and others have shown that adult mesenchymal stem cells (MSC) limit infarct size in rodents mainly through cytoprotective paracrine mechanisms. More recently, the existence of fetal MSC in the human placenta has been described but it is unknown whether these cells can mediate cardiomyocyte protection.
Methods: MSC were isolated from the placental amniotic membrane (A-MSC) of women delivering male newborns. We performed FACS analysis and FISH staining for the Y-chromosome to determine the immunophenotype and to confirm the fetal origin of the cells, respectively. The expression of several known cytoprotective factors was verified by RT-PCR. Rat neonatal cardiomyocytes (H9c2) were exposed to 6 hours of hypoxia followed by 18 hours of reoxygenation in the presence of control medium (CTRL-M) or conditioned medium (CM) from A-MSC. H9c2 viability was evaluated by MTS assay and cleaved Caspase 3 was quantified by colorimetric assay and Western blotting. The anti-apoptotic protein Bcl-2 was analyzed in H9c2 cells by Western blotting.
Results: A-MSC were successfully isolated from 15 amniotic membranes. At passage three, the A-MSC displayed the antigen profile typical of MSC and were positive for the Y chromosome. Furthermore, the A-MSC expressed several known cytoprotective factors, such as EPO, HGF, IGF-1, FGF2, VEGF, BMP2, PDGF-b, SFRP2, TGF-B, and thymosin B4. The hypoxia/reoxygenation protocol reduced by 68% the H9c2 viability (p<0.05 vs basal conditions). The A-MSC-CM remarkably increased cell viability by 62% compared with CTRL-M (p<0.05%). The colorimetric assay documented that in H9c2 fed with CRTL-M the amount of cleaved Caspase 3 was increased by 36% after hypoxia/reoxygenation (p<0.05) and that the A-MSC-CM significantly reduced the level of cleaved Caspase 3 (- 70% vs CTRL-M, p<0.05). Western blotting analysis confirmed the reduction of Caspase 3 in the presence of A-MSC-CM and showed an increase in Bcl-2 expression.
Conclusions: We documented that it is possible to consistently isolate MSC of fetal origin from human placenta. Furthermore, we showed that A-MSC express several cytoprotective factors and that A-MSC-CM remarkably protects cardiac myocytes against hypoxia/reoxygenation damage. The systematic analysis of A-MSC profile may lead to the identification of new powerful therapies to prevent myocardial reperfusion injury
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