Mechanisms of transcriptional regulation by SRF co-factors

Serum response factor (SRF) controls gene activation in response to changes in actin dynamics and mitogen-activated protein kinases. SRF has low intrinsic transcriptional activity and requires the recruitment of one of two families of co-activators: the MRTFs (myocardin-related transcription factors) and the TCFs (ternary complex factors). MRTFs are actin-binding proteins. Disruption of the actin-MRTF interaction is sufficient to induce MRTF nuclear accumulation and transcriptional activation. The TCF family are specifically activated by MAPK signalling. This thesis aims to elucidate how the SRF transcription network is controlled. The work presented encompasses two projects focused on each of the co-activator families. The regulation of MRTF shuttling from the cytoplasm to the nucleus is relatively well understood while its regulation once in the nucleus is still uncharacterized. The work demonstrates that nuclear MRTF activities are influenced by nuclear actin. Nuclear actin interferes with MRTF-DNA binding and target gene activation. In the presence of G-actin, nuclear MRTF can associate with target loci and recruit Pol II that, although traverses the gene body, does not generate stable mRNA. This inhibited state is accompanied by hypo-phosphorylation of the Pol II CTD. Dissociation of MRTF-actin interaction is required to re-establish Pol II phosphorylation and mRNA accumulation. The Erk-TCF signalling pathway was used to investigate how chromatin signatures are established in response to cues. Fibroblasts lacking all three TCFs, or reconstituted with mutant derivatives of the Elk-1 TCF were generated. Following Erk activation, chromatin immunoprecipitation and RNA-sequencing techniques, were employed to study the role of the TCFs in chromatin changes and transcriptional activation. It was possible to show that signal-induced chromatin changes occur in absence of transcription, and the specific chromatin signature requires Elk-1 DNA binding and phosphorylation. In addition analysis of the H3K27me3 mark demonstrated that Elk-1 activation is required to maintain a permissive chromatin landscape

Extremity exposure in nuclear medicine: preliminary results of a European study

The Work Package 4 of the ORAMED project, a collaborative project (2008-11) supported by the European Commission within its seventh Framework Programme, is concerned with the optimisation of the extremity dosimetry of medical staff in nuclear medicine. To evaluate the extremity doses and dose distributions across the hands of medical staff working in nuclear medicine departments, an extensive measurement programme has been started in 32 nuclear medicine departments in Europe. This was done using a standard protocol recording all relevant information for radiation exposure, i.e. radiation protection devices and tools. This study shows the preliminary results obtained for this measurement campaign. For diagnostic purposes, the two most-used radionuclides were considered: 99mTc and 18F. For therapeutic treatments, Zevalin® and DOTATOC (both labelled with 90Y) were chosen. Large variations of doses were observed across the hands depending on different parameters. Furthermore, this study highlights the importance of the positioning of the extremity dosemeter for a correct estimate of the maximum skin dose

The use of Reamer–irrigator–aspirator in the management of long bone osteomyelitis: an update

Purpose: Reamer–irrigator–aspirator (RIA) is an innovative device that its indications have recently been expanded to the management of long bone infections. Methods: In this narrative review, we summarise the most important studies in the field and we present the current open questions pertaining to the use of RIA in the management of osteomyelitis of long bones. Results: The relevant literature is sparse and low quality. Nevertheless, the use of RIA for infected cases has yielded promising outcomes in specialised centres. Technical aspects that merit special attention in osteomyelitis of long bones are its inapplicability in small diameter long bones, the inadequate debridement of wide metaphyseal areas and the potential bleeding sequelae. The use of RIA in open fracture management to reduce infection risk has not gained acceptance. The antibiotic impregnated nails and rods constitute a complimentary strategy for the management of infections. Conclusions: The use of RIA for the management of long bone infections is an innovative and promising strategy. High quality studies are needed to shed light in its efficacy compared to conventional methods of management of osteomyelitis of long bones

Update of complications and functional outcome of the ileo-pouch anal anastomosis: overview of evidence and meta-analysis of 96 observational studies

Item does not contain fulltextOBJECTIVE: The objective of this study is to provide a comprehensive update of the outcome of the ileo-pouch anal anastomosis (IPAA). DATA SOURCES: An extensive search in PubMed, EMBASE, and The Cochrane Library was conducted. STUDY SELECTION AND DATA EXTRACTION: All studies published after 2000 reporting on complications or functional outcome after a primary open IPAA procedure for UC or FAP were selected. Study characteristics, functional outcome, and complications were extracted. DATA SYNTHESIS: A review with similar methodology conducted 10 years earlier was used to evaluate developments in outcome over time. Pooled estimates were compared using a random-effects logistic meta-analyzing technique. Analyses focusing on the effect of time of study conductance, centralization, and variation in surgical techniques were performed. RESULTS: Fifty-three studies including 14,966 patients were included. Pooled rates of pouch failure and pelvic sepsis were 4.3% (95% CI, 3.5-6.3) and 7.5% (95% CI 6.1-9.1), respectively. Compared to studies published before 2000, a reduction of 2.5% was observed in the pouch failure rate (p = 0.0038). Analysis on the effect of the time of study conductance confirmed a decline in pouch failure. Functional outcome remained stable over time, with a 24-h defecation frequency of 5.9 (95% CI, 5.0-6.9). Technical surgery aspects did not have an important effect on outcome. CONCLUSION: This review provides up to date outcome estimates of the IPAA procedure that can be useful as reference values for practice and research. It is also shows a reduction in pouch failure over time.1 juli 201

A reference map of murine cardiac transcription factor chromatin occupancy identifies dynamic and conserved enhancers

Mapping the chromatin occupancy of transcription factors (TFs) is a key step in deciphering developmental transcriptional programs. Here we use biotinylated knockin alleles of seven key cardiac TFs (GATA4, NKX2-5, MEF2A, MEF2C, SRF, TBX5, TEAD1) to sensitively and reproducibly map their genome-wide occupancy in the fetal and adult mouse heart. These maps show that TF occupancy is dynamic between developmental stages and that multiple TFs often collaboratively occupy the same chromatin region through indirect cooperativity. Multi-TF regions exhibit features of functional regulatory elements, including evolutionary conservation, chromatin accessibility, and activity in transcriptional enhancer assays. H3K27ac, a feature of many enhancers, incompletely overlaps multi-TF regions, and multi-TF regions lacking H3K27ac retain conservation and enhancer activity. TEAD1 is a core component of the cardiac transcriptional network, co-occupying cardiac regulatory regions and controlling cardiomyocyte-specific gene functions. Our study provides a resource for deciphering the cardiac transcriptional regulatory network and gaining insights into the molecular mechanisms governing heart development