1,985 research outputs found
Sox10+ adult stem cells contribute to biomaterial encapsulation and microvascularization.
Implanted biomaterials and biomedical devices generally induce foreign body reaction and end up with encapsulation by a dense avascular fibrous layer enriched in extracellular matrix. Fibroblasts/myofibroblasts are thought to be the major cell type involved in encapsulation, but it is unclear whether and how stem cells contribute to this process. Here we show, for the first time, that Sox10+ adult stem cells contribute to both encapsulation and microvessel formation. Sox10+ adult stem cells were found sparsely in the stroma of subcutaneous loose connective tissues. Upon subcutaneous biomaterial implantation, Sox10+ stem cells were activated and recruited to the biomaterial scaffold, and differentiated into fibroblasts and then myofibroblasts. This differentiation process from Sox10+ stem cells to myofibroblasts could be recapitulated in vitro. On the other hand, Sox10+ stem cells could differentiate into perivascular cells to stabilize newly formed microvessels. Sox10+ stem cells and endothelial cells in three-dimensional co-culture self-assembled into microvessels, and platelet-derived growth factor had chemotactic effect on Sox10+ stem cells. Transplanted Sox10+ stem cells differentiated into smooth muscle cells to stabilize functional microvessels. These findings demonstrate the critical role of adult stem cells in tissue remodeling and unravel the complexity of stem cell fate determination
Borcherds symmetries in M-theory
It is well known but rather mysterious that root spaces of the Lie
groups appear in the second integral cohomology of regular, complex, compact,
del Pezzo surfaces. The corresponding groups act on the scalar fields (0-forms)
of toroidal compactifications of M theory. Their Borel subgroups are actually
subgroups of supergroups of finite dimension over the Grassmann algebra of
differential forms on spacetime that have been shown to preserve the
self-duality equation obeyed by all bosonic form-fields of the theory. We show
here that the corresponding duality superalgebras are nothing but Borcherds
superalgebras truncated by the above choice of Grassmann coefficients. The full
Borcherds' root lattices are the second integral cohomology of the del Pezzo
surfaces. Our choice of simple roots uses the anti-canonical form and its known
orthogonal complement. Another result is the determination of del Pezzo
surfaces associated to other string and field theory models. Dimensional
reduction on corresponds to blow-up of points in general position
with respect to each other. All theories of the Magic triangle that reduce to
the sigma model in three dimensions correspond to singular del Pezzo
surfaces with (normal) singularity at a point. The case of type I and
heterotic theories if one drops their gauge sector corresponds to non-normal
(singular along a curve) del Pezzo's. We comment on previous encounters with
Borcherds algebras at the end of the paper.Comment: 30 pages. Besides expository improvements, we exclude by hand real
fermionic simple roots when they would naively aris
Conformational dynamics of a single protein monitored for 24 hours at video rate
We use plasmon rulers to follow the conformational dynamics of a single
protein for up to 24 h at a video rate. The plasmon ruler consists of two gold
nanospheres connected by a single protein linker. In our experiment, we follow
the dynamics of the molecular chaperone heat shock protein 90, which is known
to show open and closed conformations. Our measurements confirm the previously
known conformational dynamics with transition times in the second to minute
time scale and reveals new dynamics on the time scale of minutes to hours.
Plasmon rulers thus extend the observation bandwidth 3/4 orders of magnitude
with respect to single-molecule fluorescence resonance energy transfer and
enable the study of molecular dynamics with unprecedented precision
Transforming 3D-printed mesostructures into multimodal sensors with nanoscale conductive metal oxides
Additively manufactured (AM) three-dimensional (3D) mesostructures exhibit geometrically optimal mechanical, thermal, and optical properties that could drive future microrobotics, energy harvesting, and biosensing technologies at the micrometer to millimeter scale. We present a strategy for transforming AM mesostructures into 3D electronics by growing nanoscale conducting films on 3D-printed polymers. This highly generalizable method utilizes precision atomic layer deposition (ALD) of conducting metal oxides on ultrasmooth photopolymer lattices printed by high-resolution microstereolithography. We demonstrate control of 3D electronic transport by tuning conformal growth of ultrathin amorphous and crystalline conducting metal oxides. To understand the scaling of 3D electrical properties, we apply graph theory to compute network resistance and precisely design the 3D mesostructures\u27 conductivity. Finally, we demonstrate 3D-enhanced multimodal sensing of chemical, thermal, and mechanical stimuli, geometrically boosting sensitivity by 100× over 2D films and enabling a new class of low-power, 3D-printable sensors
Assessing distributed leadership for learning and teaching quality: a multi-institutional study
Distributed leadership has been explored internationally as a leadership model that will promote and advance excellence in learning and teaching in higher education. This paper presents an assessment of how effectively distributed leadership was enabled at five Australian institutions implementing a collaborative teaching quality development scheme called the Peer Assisted Teaching Scheme. The Scheme brings together expertise from teams of academics, coordinators, and institutional learning and teaching portfolio holders to the shared goal of enhancing learning and teaching quality. A distributed leadership benchmarking tool was used to assess the Scheme’s effectiveness, and we found that (i) the Scheme is highly consistent with the distributed leadership benchmarks, and that (ii) the benchmarking tool is easily used in assessing the alignment (or otherwise) of teaching and learning quality initiatives with distributed leadership benchmarks. This paper will be of interest to those seeking to assess implementations of distributed leadership to improve teaching quality and leadership capacity
SREBP-1a activation by HBx and the effect on hepatitis B virus enhancer II/core promoter
Hepatitis B virus (HBV) X protein (HBx) plays an important role in HBV pathogenesis by regulating gene expression. Sterol regulatory element binding protein-1a (SREBP-1a) is a key transcriptional factor for modulating fatty acid and cholesterol synthesis. Here we demonstrated that HBx increased mature SREBP-1a protein level in the nucleus and its activity as a transcription factor. We further showed that the up-regulation of SREBP-1a by HBx occurred at the transcriptional level after ectopic expression and in the context of HBV replication. Deletional analysis using SREBP-1a promoter revealed that the sequence from -436 to -398 in the promoter was required for its activation by HBx. This promoter region possesses the binding sequences for two basic leucine zipper (b-ZIP) transcription factors, namely C/EBP and E4BP4. Mutagenesis of the binding sequences on the SREBP-1a promoter and ectopic expression experiments demonstrated that C/EBPα enhanced SREBP-1a activation by HBx, while E4BP4 had an inhibitory effect. C/EBPα was able to significantly reverse the inhibitory activity of E4BP4 on SREBP-1a promoter. These results demonstrated that HBx activates SREBP-1a activity at the transcription level through a complex mechanism involving two bZIP transcription factors C/EBP and E4BP4 with C/EBP being the dominant positive factor. Finally, we showed that knocking down SREBP-1 abolishes HBV enhancer II/core promoter activation by HBx.Fil: Qiao, Ling. University Of Saskatchewan; CanadáFil: Wu, Qi. University Of Saskatchewan; CanadáFil: Lu, Xinya. University Of Saskatchewan; CanadáFil: Zhou, Yan. University Of Saskatchewan; CanadáFil: Fernández Alvarez, Ana Julia. Consejo Superior de Investigaciones Cientificas; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ye, Lihong. Nankai University; ChinaFil: Zhang, Xiaodong. Nankai University; ChinaFil: Han, Jihong. Nankai University; ChinaFil: Casado, Marta. Consejo Superior de Investigaciones Cientificas; EspañaFil: Liu, Quiang. University Of Saskatchewan; Canad
Role of Placental VDR Expression and Function in Common Late Pregnancy Disorders
Vitamin D, besides its classical role in bone metabolism, plays a distinct role in multiple pathways of the feto-maternal unit. Calcitriol is the major active ligand of the nuclear vitamin D receptor (VDR). The vitamin D receptor (VDR) is expressed in different uteroplacental parts and exerts a variety of functions in physiologic pregnancy. It regulates decidualisation and implantation, influences hormone secretion and placental immune modulations. This review highlights the role of the vitamin D receptor in physiologic and disturbed pregnancy, as preeclampsia, fetal growth restriction, gestational diabetes and preterm birth. We discuss the existing literature regarding common VDR polymorphisms in these pregnancy disorders
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