No abstract

To enhance the cytocompatibility of polyvinylidene fluoride (PVDF) films, arginine-glycine-aspartic acid (RGD) peptide-click-poly(glycidyl methacrylate) (PGMA) polymer brushes were grafted onto the PVDF surface by the combination of surface-initiated atom transfer radical polymerization (ATRP) and click reaction. The direct initiation of the secondary fluorine atoms of PVDF backbone allowed for grafting of the PGMA brushes containing reactive epoxy groups. Subsequent introduction of the azide groups onto the side chain of PGMA brushes was achieved by the ring-open reaction of the epoxy groups with sodium azide. The cell adhesive RGD peptide was finally conjugated onto the PGMA brushes via alkyneazide click reaction. Kinetic studies revealed that the PGMA chain growth from the PVDF surface was consistent with a "controlled" process, and that the amount of immobilized RGD peptide on the PGMA brushes increased with the concentration of the pendant azide groups. The specificity of cellular interactions of adipose tissue-derived stem cells (ASCs) on the functionalized PVDF films was investigated. Results demonstrated that cell adhesion and proliferation of ASCs were significantly improved on the RGD-immobilized PVDF substrates, and this improvement was positively correlated with the surface concentration of covalently-bonded RGD peptide. With the inherent superior chemical and mechanical properties of PVDF films and the biocompatible nature of cell-adhesive peptides, surface functionalized PVDF films are potentially useful for biomedical and tissue engineering applications.

Multifunctional PCL hybrid surfaces are developed by grafting of REDV–zwitterionic polycarboxybetaine conjugates via surface-initiated ATRP.

Hematopoiesis in bone marrow declines during aging owing to alteration of the hematopoietic niche. However, due to difficult accessibility and other complexities, senescence-related alteration of the hematopoietic niche is largely unknown. The interstitial fluid of bone marrow (IFBM), a pivotal component of the hematopoietic niche, includes soluble secretory factors that are present between bone marrow cells. To characterize the proteomic profile changes of IFBM during aging, we analyzed the IFBMs of young, adult, and senescent rats using 2-DE combined with ESI/MALDI-Q-TOF MS. Finally, 31 differentially expressed proteins involved in multiple biological functions were identified. Peroxiredoxin 2 (Prx2), down-regulated during aging, was further analyzed and demonstrated that it is produced by bone marrow stromal cells. Interestingly, higher levels of hydrogen peroxide (H(2)O(2)) were detected in the bone marrow with lower Prx2 expression. Moreover, exogenous Prx2 reduced the intracellular H(2)O(2) level in bone marrow stromal cells in vitro. Therefore, Prx2 is implied in the regulation of H(2)O(2) production in the bone marrow during aging. Our data characterized the dynamic protein profiles of the bone marrow microenvironment during aging and we provided clues to elucidate the mechanism of creating a low ROS level in the hematopoietic niche.

Obesity is a medical condition of excess body fat negatively influencing morbidity and mortality via non-communicable disease risks. Adipogenesis, the process in which preadipocytes differentiate into adipocytes, plays a pivotal role in obesity. Our previous study proved that tannic acid (TA) showed anti-adipogenesis effect in 3T3-L1 preadipocytes. However, the precise mechanism involved in the inhibition in adipocytes differentiation by TA is unclear, and thus this is the subject of the present investigation. In this study, we determined the effect of TA on different stages of 3T3-L1 preadipocytes differentiation, and found that when treating in the early stage of differentiation, TA reduced lipid accumulation significantly. However, TA did not reduce lipid accumulation when treating in mid- and late-stages of adipocyte differentiation. To further study which gene TA had an impact on in the early stage of differentiation, we identified a number of genes associated with lipid metabolism. The results showed that compared to the control group, the mRNA levels of FAS, C/EBPα, and PPARγ were significantly decreased (p < 0.05), whereas the mRNA levels of adipsin, ap2 were increased (p < 0.05). However, TA had no effect on mRNA levels of ACC1 and ACC2. Western blot results showed that TA down-regulated the expression of PPARγ, which is a major factor in preadipocyte differentiation. In addition, TA did not affect the PI3 K/AKT pathway. These results indicate that the anti-adipogenesis effect of TA involves down-regulation of PPARγ in the early stage of 3T3-L1 preadipocyte differentiation. Some potential limitations of this study should be considered. All the results in this study were based on cell experiments. However, the human bioavailability of TA is not clear. In the present study, the concentration of TA was 5 μM; therefore, there were concerns about whether oral intake of TA could reach the effective concentrations. This important point needs to be clarified in vivo.

No abstract

Video object detection is a challenging task because of the presence of appearance deterioration in certain video frames. One typical solution is to aggregate neighboring features to enhance per-frame appearance features. However, such a method ignores the temporal relations between the aggregated frames, which is critical for improving video recognition accuracy. To handle the appearance deterioration problem, this paper proposes a temporal context enhanced network (TCENet) to exploit temporal context information by temporal aggregation for video object detection. To handle the displacement of the objects in videos, a novel DeformAlign module is proposed to align the spatial features from frame to frame. Instead of adopting a fixed-length window fusion strategy, a temporal stride predictor is proposed to adaptively select video frames for aggregation, which facilitates exploiting variable temporal information and requiring fewer video frames for aggregation to achieve better results. Our TCENet achieves state-of-the-art performance on the ImageNet VID dataset and has a faster runtime. Without bells-and-whistles, our TCENet achieves 80.3% mAP by only aggregating 3 frames.

Pharyngeal fricative occurs during the production of consonants, which makes the consonants lose or weaken in cleft palate speech. In clinical application, the automatic detection of pharyngeal fricative in cleft palate speech could provide objective and effective assistant aids for speech language pathologists. In this paper, a novel acoustic parameter is proposed to detect the existence of pharyngeal fricative in cleft palate speech. This proposed acoustic feature ICPD (Independent Consonant Prominent Distribution) reflects the movement of mouth and tongue. The experimental results show that normal fricative has the higher ICPD. The extracted ICPD feature is combined with k-nearest neighbor classifier to achieve the automatic detection of pharyngeal fricative. The proposed system is tested on 127 speech samples recorded by cleft palate patients and 94 by normal speakers of controls. The overall pharyngeal fricative detection accuracy is around 90%.