36 research outputs found
Adenovirus-mediated delivery of bFGF small interfering RNA reduces STAT3 phosphorylation and induces the depolarization of mitochondria and apoptosis in glioma cells U251
Glioblastoma multiforme (GBM) carries a dismal prognosis primarily due to its aggressive proliferation in the brain regulated by complex molecular mechanisms. One promising molecular target in GBM is over-expressed basic fibroblast growth factor (bFGF), which has been correlated with growth, progression, and vascularity of human malignant gliomas. Previously, we reported significant antitumor effects of an adenovirus-vector carrying bFGF small interfering RNA (Ad-bFGF-siRNA) in glioma in vivo and in vitro. However, its mechanisms are unknown. Signal transducer and activator of transcription 3 (STAT3) is constitutively active in GBM and correlates positively with the glioma grades. In addition, as a specific transcription factor, STAT3 serves as the convergent point of various signaling pathways activated by multiple growth factors and/or cytokines. Therefore, we hypothesized that the proliferation inhibition and apoptosis induction by Ad-bFGF-siRNA may result from the interruption of STAT3 phosphorylation. In the current study, we found that in glioma cells U251, Ad-bFGF-siRNA impedes the activation of ERK1/2 and JAK2, but not Src, decreases IL-6 secretion, reduces STAT3 phosphorylation, decreases the levels of downstream molecules CyclinD1 and Bcl-xl, and ultimately results in the collapse of mitochondrial membrane potentials as well as the induction of mitochondrial-related apoptosis. Our results offer a potential mechanism for using Ad-bFGF-siRNA as a gene therapy for glioma. To our knowledge, it is the first time that the bFGF knockdown using adenovirus-mediated delivery of bFGF siRNA and its potential underlying mechanisms are reported. Therefore, this finding may open new avenues for developing novel treatments against GBM
Adenovirus-mediated delivery of bFGF small interfering RNA increases levels of connexin 43 in the glioma cell line, U251
BACKGROUND: bFGF is an important growth factor for glioma cell proliferation and invasion, while connexin 43 is implicated in the suppression of glioma growth. Correspondingly, gliomas have been shown to have reduced, or compromised, connexin 43 expression. METHODS: In this study, a bFGF-targeted siRNA was delivered to the glioma cell line, U251, using adenovirus (Ad-bFGF-siRNA) and the expression of connexin 43 and its phosphorylation state were evaluated. U251 cells were infected with Ad-bFGF-siRNA (100, 50, or 25 MOI), and infection with adenovirus expressing green fluorescent protein (Ad-GFP) at 100 MOI served as a control. Western blotting and immunofluorescence were used to detect the expression levels, phosphorylation, and localization of connexin 43 in U251 cells infected, and not infected, with Ad-bFGF-siRNA. RESULTS: Significantly higher levels of connexin 43 were detected in U251 cells infected with Ad-bFGF-siRNA at 100 and 50 MOI than in cells infected with Ad-GFP, and the same amount of connexin 43 was detected in Ad-GFP-infected and uninfected U251 cells. Connexin 43 phosphorylation did not differ between Ad-bFGF-siRNA-infected and uninfected U251 cells. However, the ratio of phosphorylated to unphosphorylated connexin 43 in Ad-bFGF-siRNA cells was lower, and connexin 43 was predominantly localized to the cytoplasm. Using a scrape loading dye transfer assay, more Lucifer Yellow was transferred to neighboring cells in the Ad-bFGF-siRNA treated group than in the control group. CONCLUSION: To our knowledge, this is the first description of a role for connexin 43 in the inhibition of U251 growth using Ad-bFGF-siRNA
Uncertainty-Aware Consistency Regularization for Cross-Domain Semantic Segmentation
Unsupervised domain adaptation (UDA) aims to adapt existing models of the
source domain to a new target domain with only unlabeled data. Many
adversarial-based UDA methods involve high-instability training and have to
carefully tune the optimization procedure. Some non-adversarial UDA methods
employ a consistency regularization on the target predictions of a student
model and a teacher model under different perturbations, where the teacher
shares the same architecture with the student and is updated by the exponential
moving average of the student. However, these methods suffer from noticeable
negative transfer resulting from either the error-prone discriminator network
or the unreasonable teacher model. In this paper, we propose an
uncertainty-aware consistency regularization method for cross-domain semantic
segmentation. By exploiting the latent uncertainty information of the target
samples, more meaningful and reliable knowledge from the teacher model can be
transferred to the student model. In addition, we further reveal the reason why
the current consistency regularization is often unstable in minimizing the
distribution discrepancy. We also show that our method can effectively ease
this issue by mining the most reliable and meaningful samples with a dynamic
weighting scheme of consistency loss. Experiments demonstrate that the proposed
method outperforms the state-of-the-art methods on two domain adaptation
benchmarks, GTAV Cityscapes and SYNTHIA
Cityscapes
DMT: Dynamic Mutual Training for Semi-Supervised Learning
Recent semi-supervised learning methods use pseudo supervision as core idea,
especially self-training methods that generate pseudo labels. However, pseudo
labels are unreliable. Self-training methods usually rely on single model
prediction confidence to filter low-confidence pseudo labels, thus remaining
high-confidence errors and wasting many low-confidence correct labels. In this
paper, we point out it is difficult for a model to counter its own errors.
Instead, leveraging inter-model disagreement between different models is a key
to locate pseudo label errors. With this new viewpoint, we propose mutual
training between two different models by a dynamically re-weighted loss
function, called Dynamic Mutual Training (DMT). We quantify inter-model
disagreement by comparing predictions from two different models to dynamically
re-weight loss in training, where a larger disagreement indicates a possible
error and corresponds to a lower loss value. Extensive experiments show that
DMT achieves state-of-the-art performance in both image classification and
semantic segmentation. Our codes are released at
https://github.com/voldemortX/DST-CBC .Comment: Reformatte
Context-Aware Mixup for Domain Adaptive Semantic Segmentation
Unsupervised domain adaptation (UDA) aims to adapt a model of the labeled
source domain to an unlabeled target domain. Existing UDA-based semantic
segmentation approaches always reduce the domain shifts in pixel level, feature
level, and output level. However, almost all of them largely neglect the
contextual dependency, which is generally shared across different domains,
leading to less-desired performance. In this paper, we propose a novel
Context-Aware Mixup (CAMix) framework for domain adaptive semantic
segmentation, which exploits this important clue of context-dependency as
explicit prior knowledge in a fully end-to-end trainable manner for enhancing
the adaptability toward the target domain. Firstly, we present a contextual
mask generation strategy by leveraging the accumulated spatial distributions
and prior contextual relationships. The generated contextual mask is critical
in this work and will guide the context-aware domain mixup on three different
levels. Besides, provided the context knowledge, we introduce a
significance-reweighted consistency loss to penalize the inconsistency between
the mixed student prediction and the mixed teacher prediction, which alleviates
the negative transfer of the adaptation, e.g., early performance degradation.
Extensive experiments and analysis demonstrate the effectiveness of our method
against the state-of-the-art approaches on widely-used UDA benchmarks.Comment: Accepted to IEEE Transactions on Circuits and Systems for Video
Technology (TCSVT
V3 vertebral artery to anterior inferior cerebellar artery bypass with saphenous vein graft for vertebrobasilar ischemia: 3-dimensional operative video
Hierarchical porous carbon with ordered straight micro-channels templated by continuous filament glass fiber arrays for high performance supercapacitors
Hierarchical porous carbon with highly ordered straight micro-channels was prepared though a facile melt vacuum infiltration method using continuous filament glass fiber arrays as the template and glucose as the precursor. The as-prepared carbon material shows high specific surface areas up to 1880 m2 gļæ½1 profited from the unique structure of straight micro-channels. A fine pore structure is formed in the channel wall through KOH activation after the removal of the glass fiber array. electrochemical evaluation of the carbon material indicates that the hierarchical porous carbon exhibits a high specific capacitance of 283 F gļæ½1 at a current density of 0.25 A gļæ½1 with an alkaline electrolyte (6 M KOH) in a threeelectrode system. It also demonstrates excellent cycling stability with a capacity retention of 88.5% over 10 000 cycles at a high current density of 6 A gļæ½1. These exciting results demonstrate a very simple and low-cost method for large-scale preparation of electrode materials for supercapacitors
Posterior inferior cerebellar artery reimplantation: Buffer lengths, perforator anatomy, and technical limitations
Objective: Reimplantation of the posterior inferior cerebellar artery (PICA) to the vertebral artery (VA) is a safe and effective bypass option after deliberate PICA sacrifice during the treatment of nonsaccular and dissecting aneurysms at this location. However, the anatomy and limitations of this technique have not been studied. The goal of this study was to define the surgical anatomy and buffer lengths specific to the proximal segment of the PICA related to 2 variations of PICA reimplantation: 1) reimplantation along-VA (simulating a dissecting VA aneurysm), and 2) reimplantation across- VA (simulating a nonclippable, proximal PICA aneurysm). Methods: Ten cadaver heads (20 sides) were prepared for surgical simulation. Twenty far-lateral approaches were performed. The PICA was mobilized and reimplanted onto the VA according to 2 different paradigms: 1) transposition along the axis of the VA (along-VA) to simulate a dissecting VA, and 2) transposition perpendicular to the axis of the VA (across-VA) to simulate a nonclippable, proximal PICA aneurysm. The buffer lengths provided by mobilization of the artery in each paradigm were measured and the anatomy of perforator branching on the proximal PICAs was analyzed. Results; The PICA was reimplanted in all surgical simulations. The most common perforating artery on the P1 and P2 segments was the short circumflex type. No direct perforator was found on the P1 segment. The mean buffer length with reimplantation along the VA axis was 13.43 Ā± 4.61 mm, and it was 6.97 Ā± 4.04 mm with reimplantation across the VA. The PICA was less maneuverable when it was reimplanted across the VA, due to perforator branches of the PICA (P3 segment). Conclusions: The buffer lengths measured in this study describe the limitations of PICA reimplantation as a revascularization procedure for nonsaccular aneurysms in this location. PICA reimplantation is a revascularization option for dissecting VA aneurysms incorporating the PICA origin that are \u3c 13 mm in length, and for nonsaccular proximal PICA aneurysms that are \u3c 6 mm in diameter. The final decision to reimplant the PICA depends on careful inspection of perforator anatomy that is not visible preoperatively on angiography, as well as an assessment of technical difficulty intraoperatively