185 research outputs found
The role of apoptosis in the development of AGM hematopoietic stem cells revealed by Bcl-2 overexpression
Apoptosis is an essential process in embryonic tissue remodeling and adult
tissue homeostasis. Within the adult hematopoietic system, it allows for
tight regulation of hematopoietic cell subsets. Previously, it was shown
that B-cell leukemia 2 (Bcl-2) overexpression in the adult increases the
viability and activity of hematopoietic cells under normal and/or
stressful conditions. However, a role for apoptosis in the embryonic
hematopoietic system has not yet been established. Since the first
hematopoietic stem cells (HSCs) are generated within the
aortagonad-mesonephros (AGM; an actively remodeling tissue) region
beginning at embryonic day 10.5, we examined this tissue for expression of
apoptosis-related genes and ongoing apoptosis. Here, we show expression of
several proapoptotic and antiapoptotic genes in the AGM. We also generated
transgenic mice overexpressing Bcl-2 under the control of the
transcriptional regulatory elements of the HSC marker stem cell antigen-1
(Sca-1), to test for the role of cell survival in the regulation of AGM
HSCs. We provide evidence for increased numbers and viability of Sca-1(+)
cells in the AGM and subdissected midgestation aortas, the site where HSCs
are localized. Most important, our in vivo transplantation data show that
Bcl-2 overexpression increases AGM and fetal liver HSC activity, strongly
suggesting that apoptosis plays a role in HSC development
Postprandial incorporation of EPA and DHA from transgenic Camelina sativa oil into blood lipids is equivalent to that from fish oil in healthy humans
Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are important components of cell membranes. Since humans have limited ability for EPA and DHA synthesis, these must be obtained from the diet, primarily from oily fish. Dietary EPA and DHA intakes are constrained by the size of fish stocks and by food choice. Seed oil from transgenic plants that synthesise EPA and DHA represents a potential alternative source of these fatty acids, but this has not been tested in humans. We hypothesised that incorporation of EPA and DHA into blood lipids from transgenic Camelina sativa seed oil (CSO) is equivalent to that from fish oil. Healthy men and women (18 to 30 years or 50 to 65 years) consumed 450 mg EPA plus DHA from either CSO or commercial blended fish oil (BFO) in test meals in a double blind, postprandial cross-over trial. There were no significant differences between test oils or sexes in EPA and DHA incorporation into plasma triacylglycerol, phosphatidylcholine or non-esterified fatty acids over 8 hours. There were no significant differences between test oils, age groups or sexes in postprandial VLDL, LDL or HDL sizes or concentrations. There were no significant differences between test oils in postprandial plasma TNFα, interleukin 6 or 10, or soluble intercellular cell adhesion molecule-1 concentrations in younger participants. These findings show that incorporation into blood lipids of EPA and DHA consumed as CSO was equivalent to BFO and that such transgenic plant oils are a suitable dietary source of EPA and DHA in humans
Research from therapeutic radiographers : an audit of research capacity within the UK
Research from Allied Health Professionals (AHPs) is anecdotally known to lag behind that of other professions. The developing research landscape within other therapies and internationally led us to question how UK practice in therapeutic radiography was developing. The aim of the survey was to audit research capacity across therapy radiography in the UK. Method: An electronic survey was sent to Radiotherapy Service Managers (RSM) and research leads in each of the radiotherapy centres in the UK. An adapted version of the 'Auditing Research Capacity' tool (ARC © tool) was used as the basis of the questionnaire. Results: A total of 45 RSM responded to the survey (67% response rate) and 30 Research radiographers (RR) (45% response rate). A total of 51 RR were in post equating to 40.3 whole time equivalents and averaging 1 RR per centre. Variation was evident in the commitment to the development of a research culture identified by practices such as linking research to the business planning cycle, inclusion of research in recruitment and advertising materials, or having a nominated therapeutic radiographer lead on research for the department. Over a third of responding centres did not have a research strategy and training for RRs was limited; specifically in areas such as writing funding bids, writing for publication and the research and governance process. Conclusion: A number of short and long-term strategies are proposed that should enhance a positive research culture and improve research capacity for therapeutic radiography led research. These include utilisation of the existing infrastructure provided by the National Institute for Health Research, a lead or co-ordinator for research activity with a remit to motivate others. Development of links and networks, and the development of a research strategy linked to wider Trust research priorities. The research strategy should include mentoring or developing appropriate research skills for those engaged in research (including higher degree qualifications). RSMs should also encourage peer-reviewed publications, and conference presentations from all staff to ensure research results are disseminated to the wider profession
Cell shape analysis of random tessellations based on Minkowski tensors
To which degree are shape indices of individual cells of a tessellation
characteristic for the stochastic process that generates them? Within the
context of stochastic geometry and the physics of disordered materials, this
corresponds to the question of relationships between different stochastic
models. In the context of image analysis of synthetic and biological materials,
this question is central to the problem of inferring information about
formation processes from spatial measurements of resulting random structures.
We address this question by a theory-based simulation study of shape indices
derived from Minkowski tensors for a variety of tessellation models. We focus
on the relationship between two indices: an isoperimetric ratio of the
empirical averages of cell volume and area and the cell elongation quantified
by eigenvalue ratios of interfacial Minkowski tensors. Simulation data for
these quantities, as well as for distributions thereof and for correlations of
cell shape and volume, are presented for Voronoi mosaics of the Poisson point
process, determinantal and permanental point processes, and Gibbs hard-core and
random sequential absorption processes as well as for Laguerre tessellations of
polydisperse spheres and STIT- and Poisson hyperplane tessellations. These data
are complemented by mechanically stable crystalline sphere and disordered
ellipsoid packings and area-minimising foam models. We find that shape indices
of individual cells are not sufficient to unambiguously identify the generating
process even amongst this limited set of processes. However, we identify
significant differences of the shape indices between many of these tessellation
models. Given a realization of a tessellation, these shape indices can narrow
the choice of possible generating processes, providing a powerful tool which
can be further strengthened by density-resolved volume-shape correlations.Comment: Chapter of the forthcoming book "Tensor Valuations and their
Applications in Stochastic Geometry and Imaging" in Lecture Notes in
Mathematics edited by Markus Kiderlen and Eva B. Vedel Jense
Anatomical and histological characteristics of teeth in agouti (Dasyprocta prymnolopha Wagler, 1831)
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