Looking for black-holes in X-ray binaries with XMM-Newton: XTE J1817-330 and XTE J1856+053

The X-ray binary XTE J1817-330 was discovered in outburst on 26 January 2006 with RXTE/ASM. One year later, another X-ray transient discovered in 1996, XTE J1856+053, was detected by RXTE during a new outburst on 28 February 2007. We triggered XMM-Newton target of opportunity observations on these two objects to constrain their parameters and search for a stellar black holes. We summarize the properties of these two X-ray transients and show that the soft X-ray spectra indicate indeed the presence of an accreting stellar black hole in each of the two systems.Comment: to appear in the proceedings of the Second Kolkata Conference on Observational Evidence for Black Holes in the Universe, Feb. 2008, Editor Sandip Chakrabarti, AI

A Novel Cre/lox71-Based System for Inducible Expression of Recombinant Proteins and Genome Editing

In this study, we developed a novel Cre/lox71-based system for the controlled transient expression of target genes. We used the bacteriophage P1 Cre recombinase, which harbors a short, highly specific DNA-binding site and does not have endogenous binding sites within mouse or human genomes. Fusing the catalytically inactive form of Cre recombinase and the VP64 transactivation domain (VP16 tetramer), we constructed the artificial transcription factor Cre-VP64. This transcription factor binds to the lox71 sites within the promoter region of the target gene and, therefore, upregulates its expression. We tested the Cre-VP64/lox71 system for the controlled expression of several genes, including growth factors and the genome editor CRISPR/Cas9, and obtained superior efficiency in the regulation of transgene expression, achieving a high expression level upon induction together with low basal activity. This system or its modified forms can be suggested as a novel effective tool for the transitory controlled expression of target genes for functional genomic studies, as well as for gene therapy approaches

Novel Immortalized Human Multipotent Mesenchymal Stromal Cell Line for Studying Hormonal Signaling

Multipotent mesenchymal stromal cells (MSCs) integrate hormone and neuromediator signaling to coordinate tissue homeostasis, tissue renewal and regeneration. To facilitate the investigation of MSC biology, stable immortalized cell lines are created (e.g., commercially available ASC52telo). However, the ASC52telo cell line has an impaired adipogenic ability and a depressed response to hormones, including 5-HT, GABA, glutamate, noradrenaline, PTH and insulin compared to primary cells. This markedly reduces the potential of the ASC52telo cell line in studying the mechanisms of hormonal control of MSC’s physiology. Here, we have established a novel immortalized culture of adipose tissue-derived MSCs via forced telomerase expression after lentiviral transduction. These immortalized cell cultures demonstrate high proliferative potential (up to 40 passages), delayed senescence, as well as preserved primary culture-like functional activity (sensitivity to hormones, ability to hormonal sensitization and differentiation) and immunophenotype up to 17–26 passages. Meanwhile, primary adipose tissue-derived MSCs usually irreversibly lose their properties by 8–10 passages. Observed characteristics of reported immortalized human MSC cultures make them a feasible model for studying molecular mechanisms, which regulate the functional activities of these cells, especially when primary cultures or commercially available cell lines are not appropriate

Coinfection with HIV and hepatitis C virus in 229 children and young adults living in Europe

[Objective] To characterize children, adolescents and young adults infected with HIV/hepatitis C virus (HCV) vertically or before age of 18 years and living in Europe regarding mode of acquisition, HCV genotype, clinical status and treatment.[Design] Retrospective, cross-sectional study using pooled data from 11 European paediatric HIV cohorts.[Methods] Patients aged more than 18 months and less than 25 years, with HIV/HCV acquired vertically or in childhood, were included. Anonymized individual patient data were collected using a standard protocol and modified HIV Cohorts Data Exchange Protocol.[Results] Of 229 patients included, 142 (62%) had vertically acquired infection. Median age at last follow-up was 16.2 years. Most children had HCV genotype 1 (101/184, 55%) or 3 (57/184, 31%). One-fifth (46/214) had a previous AIDS diagnosis (data missing on prior AIDS diagnoses for 15). At their last clinic visit, 70% (145/208) had no/mild immunosuppression (Centers for Disease Control and Prevention stage 1), and 131 of 179 on antiretroviral therapy had undetectable HIV RNA (assay thresholds varied from <20 to <150 copies/ml). Overall, 42% (86/204) had hepatomegaly in the previous year, and 55% (116/213) had alanine aminotransferase more than 40 IU/l at their last test. Of 97 patients with transient elastography, 12 had results more than 9 kPa; this was associated with duration of HCV infection (P = 0.033), but not with CD4+ cell count, antiretroviral therapy use or sex in univariable analysis. Of 17 patients with liver biopsies, six had bridging fibrosis and one had cirrhosis. Twenty-five (11%) had been treated successfully for HCV.[Conclusion] The high proportion of patients with progressive liver disease underscores the need for close monitoring and earlier and more effective HCV treatment.This work was supported by funding from the EU Seventh Framework Programme (FP7/2007–2013) under EuroCoord grant agreement [no. 260694] and additional funding from Janssen.Peer reviewe