85 research outputs found

    McSweeney's and the challenges of the marketplace for independent publishing

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    In their article "McSweeney's and the Challenges of the Marketplace for Independent Publishing" Katrien Bollen, Stef Craps, and Pieter Vermeulen argue that the artistic projects of the US-American author, activist, and editor Dave Eggers are marked by a tension between the desire for independence and the demands of brand-building. The article offers a close analysis of the materiality and paratexts of one particular issue of McSweeney's, the literary magazine of which Eggers is the founding editor. Both the content and the apologetically aggressive tone of Eggers's editorial statements betray a deep unease with the inability to inhabit a cultural and economic position that is untainted by the compromises that publishing requires. Still, this disavowed complicity with the market in fact sustains Eggers's editorial practice in McSweeney's, which, in marked contrast to his explicit statements, thrives on a dynamic of commodification

    The proton sponge hypothesis : fable or fact?

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    In non-viral gene therapy, cationic polymers and lipids are frequently used to encapsulate macromolecular therapeutics into nanoparticles. During their journey to deliver the cargo to the intended intracellular target, many biological barriers need to be overcome. One of the major bottlenecks for efficient transfection is the endosomal barrier since nanoparticles often remain entrapped inside endosomes and are trafficked towards the lysosomes where the cargo is degraded. For cationic polymers, the proton sponge hypothesis was introduced in the late '90s as a way to explain their endosomal escape properties. However, to date, no consensus has been reached in the scientific community about the validity of this hypothesis due to many contradictory reports. Here we review the sometimes conflicting reports that have been published on the proton sponge hypothesis. We also discuss membrane destabilization and polymer swelling as additional factors that might influence endosomal escape of polyplexes. Based on the key publications on this subject, we aim to launch a consensus on the role of the proton sponge hypothesis in endosomal escape

    Endosomal size and membrane leakiness influence proton sponge-based rupture of endosomal vesicles

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    In gene therapy, endosomal escape represents a major bottleneck since nanoparticles often remain entrapped inside endosomes and are trafficked toward the lysosomes for degradation. A detailed understanding of the endosomal barrier would be beneficial for developing rational strategies to improve transfection and endosomal escape. By visualizing individual endosomal escape events in live cells, we obtain insight into mechanistic factors that influence proton sponge-based endosomal escape. In a comparative study, we found that HeLa cells treated with JetPEI/pDNA polyplexes have a 3.5-fold increased endosomal escape frequency compared to ARPE-19 cells. We found that endosomal size has a major impact on the escape capacity. The smaller HeLa endosomes are more easily ruptured by the proton sponge effect than the larger ARPE-19 endosomes, a finding supported by a mathematical model based on the underlying physical principles. Still, it remains intriguing that even in the small HeLa endosomes, <10% of the polyplex-containing endosomes show endosomal escape. Further experiments revealed that the membrane of polyplex-containing endosomes becomes leaky to small compounds, preventing effective buildup of osmotic pressure, which in turn prevents endosomal rupture. Analysis of H1299 and A549 cells revealed that endosomal size determines endosomal escape efficiency when cells have comparable membrane leakiness. However, at high levels of membrane leakiness, buildup of osmotic pressure is no longer possible, regardless of endosomal size. Based on our findings that both endosomal size and membrane leakiness have a high impact on proton sponge-based endosomal rupture, we provide important clues toward further improvement of this escape strategy

    Quantifying the average number of nucleic acid therapeutics per nanocarrier by single particle tracking microscopy

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    Nucleic acid biopharmaceuticals are being investigated as potential therapeutics. They need to be incorporated into a biocompatible carrier so as to overcome several biological barriers. Rational development of suitable nanocarriers requires high-quality characterization techniques. While size, concentration, and stability can be very well measured these days, even in complex biological fluids, a method to accurately quantify the number of nucleic acid therapeutics encapsulated in nanocarriers is still missing. Here we present a method, based on concentration measurements with single particle tracking microscopy, with which it is possible to directly measure the number of plasmid DNA molecules per nanoparticle, referred to as the plasmid/NP ratio. Using DOTAP/DOPE liposomes as a model carrier, we demonstrate the usefulness of the method by investigating the influence of various experimental factors on the plasmid/NP ratio. We find that the plasmid/NP ratio is inversely proportional with the size of the pDNA and that the plasmid/NP decreases when lipoplexes are prepared at lower concentrations of pDNA and nanocarrier, with values ranging from 6.5 to 3 plasmid/NP. Furthermore, the effect of pre- and post-PEGylation of lipoplexes was examined, finding that pre-PEGylation results in a decreased plasmid/NP ratio, while post-PEGylation did not alter the plasmid/NP ratio. These proof-of-concept experiments show that single particle tracking offers an extension of the nanoparticle characterization toolbox and is expected to aid in the efficient development of nanoformulations for nucleic acid-based therapies

    Learning experiences of final-year student midwives inlabor wards : a qualitative exploratory study

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    Introduction: Clinical placements are an integral part of midwifery education and are crucial for achieving professional competencies. Although students’ experiences on placements have been shown to play a meaningful role in their learning, they have received scant attention in the literature. The aim of this paper is to describe the learning experiences of final-year student midwives in labor wards within the Brussels metropolitan region, Belgium. Methods: A qualitative exploratory study was conducted using two focus groups (N=20). Data analysis included: transcription of audio recordings, thematic content analysis with coding into recurrent and common themes, and broader categories. Discussions among researchers were incorporated in all phases of the analysis for integrity and data fit. Results: Data analysis identified the following categories as determining student learning experiences in labor wards: 1) managing opportunities, 2) being supported, and 3) dealing with the environment. Overall, respondents were positive and enthusiastic about their learning experiences, although some felt tense and unprepared. Students expressed concerns about differences in learning opportunities between placements and found it challenging to achieve all competencies. Student learning experiences were enhanced when they had placements for longer periods with the same supportive mentors. Conclusions: Factors related to students’ functioning, the healthcare professional, midwifery education and hospital environment affected their learning in labor wards. The combination of a more persevered preparation of students and mentors, together with a student-centered organization of placements, is crucial to create a positive learning experience for midwifery students in labor wards

    Absence of BCL-2 expression identifies a subgroup of AML with distinct phenotypic, molecular, and clinical characteristics

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    Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the rapid and uncontrolled clonal growth of myeloid lineage cells in the bone marrow. The advent of oral, selective inhibitors of the B-cell leukemia/lymphoma-2 (BCL-2) apoptosis pathway, such as venetoclax, will likely induce a paradigm shift in the treatment of AML. However, the high cost of this treatment and the risk of additive toxicity when used in combination with standard chemotherapy represent limitations to its use and underscore the need to identify which patients are most-and least-likely to benefit from incorporation of venetoclax into the treatment regimen. Bone marrow specimens from 93 newly diagnosed AML patients were collected in this study and evaluated for BCL-2 protein expression by immunohistochemistry. Using this low-cost, easily, and readily applicable analysis method, we found that 1 in 5 AML patients can be considered as BCL-2(-). In addition to a lower bone marrow blast percentage, this group exhibited a favorable molecular profile characterized by lower WT1 expression and underrepresentation of FLT3 mutations. As compared to their BCL-2(+) counterparts, the absence of BCL-2 expression was associated with a favorable response to standard chemotherapy and overall survival, thus potentially precluding the necessity for venetoclax add-on

    Plasmid-based genetic modification of human bone marrow-derived stromal cells: analysis of cell survival and transgene expression after transplantation in rat spinal cord

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    <p>Abstract</p> <p>Background</p> <p>Bone marrow-derived stromal cells (MSC) are attractive targets for <it>ex vivo </it>cell and gene therapy. In this context, we investigated the feasibility of a plasmid-based strategy for genetic modification of human (h)MSC with enhanced green fluorescent protein (EGFP) and neurotrophin (NT)3. Three genetically modified hMSC lines (EGFP, NT3, NT3-EGFP) were established and used to study cell survival and transgene expression following transplantation in rat spinal cord.</p> <p>Results</p> <p>First, we demonstrate long-term survival of transplanted hMSC-EGFP cells in rat spinal cord under, but not without, appropriate immune suppression. Next, we examined the stability of EGFP or NT3 transgene expression following transplantation of hMSC-EGFP, hMSC-NT3 and hMSC-NT3-EGFP in rat spinal cord. While <it>in vivo </it>EGFP mRNA and protein expression by transplanted hMSC-EGFP cells was readily detectable at different time points post-transplantation, <it>in vivo </it>NT3 mRNA expression by hMSC-NT3 cells and <it>in vivo </it>EGFP protein expression by hMSC-NT3-EGFP cells was, respectively, undetectable or declined rapidly between day 1 and 7 post-transplantation. Further investigation revealed that the observed <it>in vivo </it>decline of EGFP protein expression by hMSC-NT3-EGFP cells: (i) was associated with a decrease in transgenic NT3-EGFP mRNA expression as suggested following laser capture micro-dissection analysis of hMSC-NT3-EGFP cell transplants at day 1 and day 7 post-transplantation, (ii) did not occur when hMSC-NT3-EGFP cells were transplanted subcutaneously, and (iii) was reversed upon re-establishment of hMSC-NT3-EGFP cell cultures at 2 weeks post-transplantation. Finally, because we observed a slowly progressing tumour growth following transplantation of all our hMSC cell transplants, we here demonstrate that omitting immune suppressive therapy is sufficient to prevent further tumour growth and to eradicate malignant xenogeneic cell transplants.</p> <p>Conclusion</p> <p>In this study, we demonstrate that genetically modified hMSC lines can survive in healthy rat spinal cord over at least 3 weeks by using adequate immune suppression and can serve as vehicles for transgene expression. However, before genetically modified hMSC can potentially be used in a clinical setting to treat spinal cord injuries, more research on standardisation of hMSC culture and genetic modification needs to be done in order to prevent tumour formation and transgene silencing <it>in vivo</it>.</p
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