Boundary-oriented Network for Automatic Breast Tumor Segmentation in Ultrasound Images.

Breast cancer is considered as the most prevalent cancer. Using ultrasound images is a momentous clinical diagnosis method to locate breast tumors. However, accurate segmentation of breast tumors remains an open problem due to ultrasound artifacts, low contrast, and complicated tumor shapes in ultrasound images. To address this issue, we proposed a boundary-oriented network (BO-Net) for boosting breast tumor segmentation in ultrasound images. The BO-Net boosts tumor segmentation performance from two perspectives. Firstly, a boundary-oriented module (BOM) was designed to capture the weak boundaries of breast tumors by learning additional breast tumor boundary maps. Second, we focus on enhanced feature extraction, which takes advantage of the Atrous Spatial Pyramid Pooling (ASPP) module and Squeeze-and-Excitation (SE) block to obtain multi-scale and efficient feature information. We evaluate our network on two public datasets: Dataset B and BUSI. For the Dataset B, our network achieves 0.8685 in Dice, 0.7846 in Jaccard, 0.8604 in Precision, 0.9078 in Recall, and 0.9928 in Specificity. For the BUSI dataset, our network achieves 0.7954 in Dice, 0.7033 in Jaccard, 0.8275 in Precision, 0.8251 in Recall, and 0.9814 in Specificity. Experimental results show that BO-Net outperforms the state-of-the-art segmentation methods for breast tumor segmentation in ultrasound images. It demonstrates that focusing on boundary and feature enhancement creates more efficient and robust breast tumor segmentation.

Tailoring Intermolecular Interactions Towards High-Performance Thermoelectric Ionogels at Low Humidity.

Development of ionic thermoelectric (iTE) materials is of immense interest for efficient heat-to-electricity conversion due to their giant ionic Seebeck coefficient (Si ), but challenges remain in terms of relatively small Si at low humidity, poor stretchability, and ambiguous interaction mechanism in ionogels. Herein, a novel ionogel is reported consisting of polyethylene oxide (PEO), polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), and 1-ethyl-3-methylimidazolium acetate (Emim:OAC). By delicately designing the interactions between ions and polymers, the migration of anions is restricted due to their strong binding with the hydroxyl groups of polymers, while the transport of cations is facilitated through segmental motions due to the increased amorphous regions, thereby leading to enlarged diffusion difference between the cations and anions. Moreover, the plasticizing effect of P123 and Emim:OAC can increase the elongation at break. As a consequence, the ionogel exhibits excellent properties including high Si (18 mV K-1 at relative humidity of 60%), good ionic conductivity (1.1 mS cm-1 ), superior stretchability (787%), and high stability (over 80% retention after 600 h). These findings show a promising strategy to obtain multifunctional iTE materials by engineering the intermolecular interactions and demonstrate the great potential of ionogels for harvesting low-grade heat in human-comfortable humidity environments.

Composite Film of Vanadium Dioxide Nanoparticles and Ionic Liquid-Nickel-Chlorine Complexes with Excellent Visible Thermochromic Performance.

Vanadium dioxide (VO2), as a typical thermochromic material used in smart windows, is always limited by its weaker solar regulation efficiency (ΔTsol) and lower luminous transmittance (Tlum). Except for common approaches such as doping, coating, and special structure, compositing is another effective method. The macroscopic thermochromic (from colorless to blue) ionic liquid-nickel-chlorine (IL-Ni-Cl) complexes are selected in this paper to be combined with VO2 nanoparticles forming a composite film. This novel scheme demonstrates outstanding optical properties: ΔTsol = 26.45% and Tlum,l = 66.44%, Tlum,h = 43.93%. Besides, the addition of the IL-Ni-Cl complexes endows the film with an obvious color change from light brown to dark green as temperature rises. This splendid visible thermochromic performance makes the composite film superior in function exhibiting and application of smart windows.

Comparison studies of the in vivo treatment of full-thickness excisional wounds and burns by an artificial bilayer dermal equivalent and J-1 acellular dermal matrix.

The effects upon skin repair were compared between a homemade bilayer dermal equivalent (BDE), composed of a collagen/chitosan porous scaffold and a silicone membrane, and J-1 acellular dermal matrix (ADM), a commercial ADM that is used widely in China to treat various skin defects. Full-thickness excisional and burn wounds were prepared on the backs of pigs and then treated with the BDE and J-1 ADM. Biopsy specimens were harvested on days 7, 14, and 21 after surgery for gross, biochemical, and molecular examinations. In comparison with the burn wounds, the excisional wounds showed accelerated granular tissue formation and superior integration with the equivalents, regardless of their type. Immunohistochemical, immunofluorescence, real time quantitative polymerase chain reaction and Western blotting analyses showed that the vascularization rates in the excisional wounds group were also significantly faster than those of the burn group for both dermal equivalents. There was no significant difference between J-1 ADM and BDE treatment on the formation of newly formed blood vessels for the excisional wounds at days 7, 14, and 21. However, there was a significant difference in the number of nascent blood vessels formed in the burn wounds after treatment with J-1 ADM compared with BDE. The highest numbers of newly formed and mature blood vessels were present in the J-1 ADM-treated excisional wounds after 21 days. Ultrathin skin grafts were further transplanted on to the regenerated dermis for 28 days, resulting in the repair of the full-thickness wounds and production of a structure similar to normal skin.

The healing of full-thickness burns treated by using plasmid DNA encoding VEGF-165 activated collagen-chitosan dermal equivalents.

Repair of deep burn by use of the dermal equivalent relies strongly on the angiogenesis and thereby the regeneration of dermis. To enhance the dermal regeneration, in this study plasmid DNA encoding vascular endothelial growth factor-165 (VEGF-165)/N,N,N-trimethyl chitosan chloride (TMC) complexes were loaded into a bilayer porous collagen-chitosan/silicone membrane dermal equivalents (BDEs), which were applied for treatment of full-thickness burn wounds. The DNA released from the collagen-chitosan scaffold could remain its supercoiled structure but its degree was decayed along with the prolongation of incubation time. The released DNA could transfect HEK293 cells in vitro with decayed efficiency too. Human umbilical vein endothelial cells (HUVECs) in vitro cultured in the scaffold loaded with TMC/pDNA-VEGF complexes expressed a significantly higher level of VEGF and showed higher viability than those cultured in the controls, i.e. blank scaffold, and scaffolds loaded with naked pDNA-VEGF and TMC/pDNA-eGFP, respectively. The four different BDEs were then transplanted in porcine full-thickness burn wounds. Results showed that the TMC/pDNA-VEGF group had a significantly higher number of newly-formed and mature blood vessels, and fastest regeneration of the dermis. RT-qPCR and western blotting found that the experimental group also had the highest expression of VEGF, CD31 and α-SMA in both mRNA and protein levels. Furthermore, ultra-thin skin grafting was performed on the regenerated dermis 14 days later, leading to complete repair of the burn wounds with normal histology. Moreover, the tensile strength of the repaired tissue increased along with the time prolongation of post grafting, resulting in a value of approximately 70% of the normal skin at 105 days.

Enhanced angiogenesis of gene-activated dermal equivalent for treatment of full thickness incisional wounds in a porcine model.

Angiogenesis of dermal equivalent is one of the key issues for treatment of full thickness skin defects. To develop a gene-activated bilayer dermal equivalent (BDE), N,N,N-trimethyl chitosan chloride (TMC), a cationic gene delivery vector, was used to form complexes with the plasmid DNA encoding vascular endothelial growth factor-165 (VEGF-165), which was then incorporated into a collagen-chitosan/silicone membrane scaffold. To evaluate the angiogenesis property in vivo, full thickness skin defects were made on the back of pigs, into which the TMC/pDNA-VEGF complexes loaded BDE and other three control BDEs, i.e. the blank BDE, and the BDEs loaded with pDNA-VEGF and TMC/pDNA-eGFP complexes, respectively, were transplanted. Biopsy specimens were harvested at day 7, 10 and 14 after surgery for histology, immunohistochemistry, immunofluorescence, real-time quantitative PCR (RT-qPCR) and western blotting analyses. The results showed that the TMC/pDNA-VEGF group had the strongest VEGF expression in mRNA and protein levels, resulting in the highest densities of newly-formed and mature vessels. The ultra-thin skin graft was further transplanted onto the dermis regenerated by the TMC/pDNA-VEGF complexes loaded BDE at day 10 and well survived. At 112 days grafting, the healing skin had a similar structure and approximately 80% tensile strength of the normal skin.

[Mechanisms and effects of biosynthesis and apoptosis in repair of full-thickness skin defect with collagen-chitosan dermal stent].

OBJECTIVE: To investigate biosynthetic and apoptotic mechanisms in repair of full thickness skin defect with collagen-chitosan porous scaffold transplantation, and to determinate differences between wound repair with the scaffold transplantation and scar healing without the scaffold transplantation. METHODS: The full thickness skin defects were made on 10 Bama miniature pigs and the bilayer dermal equivalent (BDE) composed of collagen-chitosan porous scaffold and silicone membrane was transplanted on wounds. Surfaces of wounds were observed at 1, 2, and 3 weeks after the BDE transplantation, and so were done the wound repairs after epidermis had been grafted for 2 weeks on surface of the scaffold which had been transplanted on skin defect wounds for 2 weeks. At the same time, TGF-beta1 expressions, apoptosis and self collagen replacement of scaffolds in wounds were detected in situ by immunohistochemical staining, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) and picrosirius red polarized light. Wounds without scaffold transplantation were studied as control. RESULTS: 1) Wounds with the scaffold transplantation were different from granulation tissue. 2) The peak of TGF-beta1 expression in the scaffold wounds was from 1 to 2 weeks after BDE transplantation, and TGF-beta1 expressions decreased continuously from 3 to 4 weeks. TGF-beta1 expressions increased continuously in the control wounds from 1 to 3 weeks and decreased on 4 weeks. TGF-beta1 expressions in the scaffold wounds on 1st and 2nd week were significantly higher than those in the corresponding control wounds, whereas, TGF-beta1 expressions in the scaffold wounds on 3rd and 4th week were significantly lower than those in the corresponding control wounds. 3) Apoptosis increased continuously in the scaffold wounds from 2 to 4 weeks after BDE transplantation, and so did in the control wounds from 3 to 4 weeks. However, apoptosis signals in the scaffold wounds on 2nd, 3rd, and 4th week after BDE transplantation were significantly more than those in the corresponding control wounds, and there was no difference between apoptosis signals in the scaffold wounds on 1st week after BDE transplantation and those in the corresponding control wounds. 4) Observation by picrosirius red polarized light method: self collagen began to synthesize in the scaffold wounds on 1st week after BDE transplantation, and scaffolds had been replaced by self collagen from 2 to 3 weeks after BDE transplantation. CONCLUSIONS: Collagen-chitosan porous scaffold plays a very important role in wound healing of full thickness skin defect. The mechanisms of wound repair by dermal scaffold are different from those by granulation and scar healing. It has a good future in repairing skin defect.

[Study on repair of full-thickness skin defect with collagen-chitosan dermal stent in pigs].

OBJECTIVE: To investigate angiogenesis of collagen-chitosan porous scaffold, and to study survive of skin grafts on the scaffold after bilayer dermal equivalent (BDE) was transplanted on wounds with full thickness skin defects. METHODS: The full thickness skin defects were made on 10 Bama miniature pigs and the BDE composed of collagen-chitosan porous scaffold and silicone membrane was transplanted on wound. Angiogenesis in dermal equivalent, wound healing, and healing and survive of skin grafts on dermal equivalent were observed in 1, 2, and 3 weeks after the BDE transplantation. At the same time, CD34 positive signals (neo-forming micro-vessels) were detected by immunohistochemical staining. RESULTS: Inflammatory cells and fibroblasts infiltrated into dermal equivalent and a few new micro-vessels had been formed in 1 week after the BDE transplantation; neo-forming micro-vessels perpendicular to wound bed had increased significantly in 2 weeks after the BDE transplantation; neo-forming micro-vessels could be observed in almost all dermal equivalents in 3 weeks after the BDE transplantation. CD34 positive signals (neo-forming micro-vessels) in 3 weeks after the BDE transplantation was much more than those in 2 weeks after the BDE transplantation, and CD34 positive signals in 2 weeks after the BDE transplantation was much more than those in 1 week after the BDE transplantation. Survival rate of intermediate split thickness skin graft were 10%, 70% and 100% respectively after the skin grafts had been grafted for 2 weeks on surface of the scaffold which had been transplanted for 1, 2 and 3 weeks. Epidermis which had been grafted on surface of the scaffold for 1 or 2 weeks could perfectly survive after BDE had been transplanted for 1 or 2 weeks. CONCLUSIONS: Collagen-chitosan porous scaffold plays a very important role in wound healing of full thickness skin defect and can induce fibroblast infiltration and new micro-vessel formation. Epidermis grafted on surface of collagen-chitosan porous scaffold can perfectly repair wounds, and it has brilliant applied prospects in repairing skin defect.