Numerical study on the effect of in-situ stress on smoothwall blasting in deep tunnelling

In the present study,a numerical model is first calibrated against the crack networks and pressure attenuation data in laboratory blasting test.Then,based on the calibrated numerical model,two-hole plane models are developed and used to perform a series of sim-ulations of smoothwall blasting in deep tunnelling subjected to in-situ stress.The evolutions of rock fracture and excavation damage zone in the roof/floor and sidewalls under different far-field hydrostatic pressure and anisotropic in-situ stress conditions are numerically investigated.The findings in numerical modelling are also analytically interpreted with the stress distributions around the designed tunnel perimeter and perimeter borehole.The numerical and analytical results show that the variations of rock cracking and excavation dam-aged zone induced by smoothwall blasting with in-situ stress are mainly attributed to the high tangential compressive stress concentration around the remaining rock after inner primary blasts and the tensile stress acting on the wall of perimeter hole,which control the crack propagation and initiation respectively.At last,the implications of findings for practical smoothwall blasting in deep tunnelling are discussed.

纳米医学设计诱导自噬增强的癌细胞铁死亡

铁死亡和自噬是细胞程序性死亡的两种典型形式,并且在肿瘤治疗中起到重要作用.然而,将诱导癌细胞铁死亡和自噬用于肿瘤的协同治疗仍然存在很大的挑战.因此,本文设计了一种负载海藻糖(自噬诱导剂)的mSiO_(2)@MnO_(x)-mPEG纳米颗粒.该纳米颗粒具有较好的药物负载能力、肿瘤微环境响应性控释性能和优异的生物安全性.重要的是,它能够基于肿瘤部位高表达的谷胱甘肽,通过抑制GPX4的表达诱导癌细胞铁死亡.此外,海藻糖的释放能够诱导癌细胞过度自噬,并通过NCOA4介导的铁蛋白降解进一步增强癌细胞铁死亡效果.本研究在体内外实验中均取得了很好的肿瘤治疗效果,为肿瘤的纳米治疗提供了一个有效的新思路.

Platelet-rich plasma accelerates skin wound healing by promoting re-epithelialization

Background:Autologous platelet-rich plasma(PRP)has been suggested to be effective for wound healing.However,evidence for its use in patients with acute and chronic wounds remains insufficient.The aims of this study were to comprehensively examine the effectiveness,synergy and possible mechanism of PRP-mediated improvement of acute skin wound repair.Methods:Full-thickness wounds were made on the back of C57/BL6 mice.PRP or saline solution as a control was administered to the wound area.Wound healing rate,local inflammation,angiogenesis,re-epithelialization and collagen deposition were measured at days 3,5,7 and 14 after skin injury.The biological character of epidermal stem cells(ESCs),which reflect the potential for re-epithelialization,was further evaluated in vitro and in vivo.Results:PRP strongly improved skin wound healing,which was associated with regulation of local inflammation,enhancement of angiogenesis and re-epithelialization.PRP treatment significantly reduced the production of inflammatory cytokines interleukin-17A and interleukin-1β.An increase in the local vessel intensity and enhancement of re-epithelialization were also observed in animals with PRP administration and were associated with enhanced secretion of growth factors such as vascular endothelial growth factor and insulin-like growth factor-1.Moreover,PRP treatment ameliorated the survival and activated the migration and proliferation of primary cultured ESCs,and these effects were accompanied by the differentiation of ESCs into adult cells following the changes of CD49f and keratin 10 and keratin 14.Conclusion:PRP improved skin wound healing by modulating inflammation and increasing angiogenesis and re-epithelialization.However,the underlying regulatory mechanism needs to be investigated in the future.Our data provide a preliminary theoretical foundation for the clinical administration of PRP in wound healing and skin regeneration.

Neutralization of interleukin-17A alleviates burn-induced intestinal barrier disruption via reducing pro-inflammatory cytokines in a mouse model

Background:The intestinal barrier integrity can be disrupted due to burn injury,which is responsible for local and systemic inflammatory responses.Anti-inflammation strategy is one of the proposed therapeutic approaches to control inflammatory cascade at an early stage.Interleukin-17A(IL-17A)plays a critical role in inflammatory diseases.However,the role of IL-17A in the progression of burn-induced intestinal inflammation is poorly understood.In this study,we aimed to investigate the effect of IL-17A and associated pro-inflammatory cytokines that were deeply involved in the pathogenesis of burn-induced intestinal inflammatory injury,and furthermore,we sought to determine the early source of IL-17A in the intestine.Methods:Mouse burn model was successfully established with infliction of 30%total body surface area scald burn.The histopathological manifestation,intestinal permeability,zonula occludens-1 expression,pro-inflammatory cytokines were determined with or without IL-17A-neutralization.Flow cytometry was used to detect the major source of IL-17A^(+)cells in the intestine.Results:Burn caused intestinal barrier damage,increase of intestinal permeability,alteration of zonula occludens-1 expressions,elevation of IL-17A,IL-6,IL-1βand tumor necrosis factor-α(TNF-α),whereas IL-17A neutralization dramatically alleviated burn-induced intestinal barrier disruption,maintained zonula occludens-1 expression,and noticeably,inhibited pro-inflammatory cytokines elevation.In addition,we observed that the proportion of intestinal IL-17A^(+)Vγ4^(+)T subtype cells(but not IL-17A^(+)Vγ1^(+)T subtype cells)were increased in burn group,and neutralization of IL-17A suppressed this increase.Conclusions:The main original findings of this study are intestinal mucosa barrier is disrupted after burn through affecting the expression of pro-inflammatory cytokines,and a protective role of IL-17A neutralization for intestinal mucosa barrier is determined.Furthermore,Vγ4^(+)T cells are identified as the major early producers of IL-17A that orchestrate an inflammatory response in the burn model.These data suggest that IL-17A blockage may provide a unique target for therapeutic intervention to treat intestinal insult after burn.

Photodynamic therapy accelerates skin wound healing through promoting re-epithelialization

Background:Epidermal stem cells(EpSCs)that reside in cutaneous hair follicles and the basal layer of the epidermis are indispensable for wound healing and skin homeostasis.Little is known about the effects of photochemical activation on EpSC differentiation,proliferation and migration during wound healing.The present study aimed to determine the effects of photodynamic therapy(PDT)on wound healing in vivo and in vitro.Methods:We created mouse full-thickness skin resection models and applied 5-aminolevulinic acid(ALA)for PDT to the wound beds.Wound healing was analysed by gross evaluation and haematoxylin–eosin staining in vivo.In cultured EpSCs,protein expression was measured using flow cytometry and immunohistochemistry.Cell migration was examined using a scratch model;apoptosis and differentiation were measured using flow cytometry.Results:PDT accelerated wound closure by enhancing EpSC differentiation,proliferation and migration,thereby promoting re-epithelialization and angiogenesis.PDT inhibited inflammatory infiltration and expression of proinflammatory cytokines,whereas the secretion of growth factors was greater than in other groups.The proportion of transient amplifying cells was significantly greater in vivo and in vitro in the PDT groups.EpSC migration was markedly enhanced after ALAinduced PDT.Conclusions:Topical ALA-induced PDT stimulates wound healing by enhancing re-epithelialization,promoting angiogenesis as well as modulating skin homeostasis.This work provides a preliminary theoretical foundation for the clinical administration of topical ALA-induced PDT in skin wound healing.

P311 promotes typeⅡtransforming growth factor-βreceptor mediated fibroblast activation and granulation tissue formation in wound healing

Background:P311,a highly conserved 8 kDa intracellular protein,has recently been reported to play an important role in aggravating hypertrophic scaring by promoting the differentiation and secretion of fibroblasts.Nevertheless,how P311 regulates the differentiation and function of fibroblasts to affect granulation tissue formation remains unclear.In this work,we studied the underlying mechanisms via which P311 affects fibroblasts and promotes acute skin wound repair.Methods:To explore the role of P311,both in vitro and in vivo wound-healing models were used.Full-thickness skin excisional wounds were made in wild-type and P311−/−C57 adult mice.Wound healing rate,re-epithelialization,granulation tissue formation and collagen deposition were measured at days 3,6 and 9 after skin injury.The biological phenotypes of fibroblasts,the expression of target proteins and relevant signaling pathways were examined both in vitro and in vivo.Results:P311 could promote the proliferation and differentiation of fibroblasts,enhance the ability of myofibroblasts to secrete extracellular matrix and promote cell contraction,and then facilitate the formation of granulation tissue and eventually accelerate skin wound closure.Importantly,we discovered that P311 acts via up-regulating the expression of type II transforming growth factor-βreceptor(TGF-βRII)in fibroblasts and promoting the activation of the TGF-βRII-Smad signaling pathway.Mechanistically,the mammalian target of rapamycin signaling pathway is closely implicated in the regulation of the TGF-βRII-Smad pathway in fibroblasts mediated by P311.Conclusions:P311 plays a critical role in activation of the TGF-βRII-Smad pathway to promote fibroblast proliferation and differentiation as well as granulation tissue formation in the process of skin wound repair.

Obstruction of the formation of granulation tissue leads to delayed wound healing after scald burn injury in mice

Background:Delayed wound healing remains a common but challenging problem in patients with acute or chronic wound following accidental scald burn injury.However,the systematic and detailed evaluation of the scald burn injury,including second-degree deep scald(SDDS)and thirddegree scald(TDS),is still unclear.The present study aims to analyze the wound-healing speed,the formation of granulation tissue,and the healing quality after cutaneous damage.Methods:In order to assess SDDS and TDS,the models of SDDS and TDS were established using a scald instrument in C57BL/6 mice.Furthermore,an excisional wound was administered on the dorsal surface in mice(Cut group).The wound-healing rate was first analyzed at days 0,3,5,7,15 and 27,with the Cut group as a control.Then,on the full-thickness wounds,hematoxylin and eosin(H&E)staining,Masson staining,Sirius red staining,Victoria blue staining and immunohistochemistry were performed to examine re-epithelialization,the formation of granulation tissue,vascularization,inflammatory infiltration and the healing quality at different time points in the Cut,SDDS and TDS groups.Results:The presented data revealed that the wound-healing rate was higher in the Cut group,when compared with the SDDS and TDS groups.H&E staining showed that re-epithelialization,formation of granulation tissue and inflammatory infiltration were greater in the Cut group,when compared with the SDDS and TDS groups.Immunohistochemistry revealed that the number of CD31,vascular endothelial growth factor A,transforming growth factor-βandα-smooth muscle actin reached preferential peak in the Cut group,when compared with other groups.In addition,Masson staining,Sirius red staining,Victoria blue staining,Gordon-Sweets staining and stress analysis indicated that the ratio of collagen I to III,reticular fibers,failure stress,Young’s modulus and failure length in the SDDS group were similar to those in the normal group,suggesting that healing quality was better in the SDDS group,when compared with the Cut and TDS groups.Conclusion:Overall,the investigators first administered a comprehensive analysis in the Cut,SDDS and TDS groups through in vivo experiments,which further proved that the obstacle of the formation of granulation tissue leads to delayed wound healing after scald burn injury in mice.

Nanomedicine-Leveraged Intratumoral Coordination and Redox Reactions of Dopamine for Tumor-Specific Chemotherapy

Great efforts have been made in investigating the neurotoxicity of dopamine(DA)in the presence of manganous ions.In contrast,here,we probe the possibility of DA-based cancer chemotherapy by leveraging intratumoral redox reactions of DA for producing cytotoxic species in situ.For this purpose,we have constructed a Mn-engineered,DA-loaded nanomedicine.Based on the unique size effect of the nanocarrier,this nanomedicine will not enter the central nervous system but can effectively accumulate in the tumor region,after which the nanocarrier can degrade to release Mn^(2+)and DA in response to the mild acidic intracelluar microenvironment of cancer cells.DA can chelate Mn^(2+)to form a binary coordination complex,where the strong metal-ligand interaction significantly promotes electron delocalization and elevates the reducibility of Mn center,favoring two sequential one-electron oxygen reduction reactions forming H_(2)O_(2),which can be further converted into highly oxidizing ·OH under the cocatalysis by Mn^(2+)and intracellular Fe^(2+).Additionally,as a twoelectron oxidation product of DA ligand,DA-oquinone is potent in exhausting cellular sulfhydryl and depleting reduced glutathione,inhibiting the intrinsic antioxidative mechanism of cancer cells,finally triggering severe oxidative damages in a synergistic manner.It is expected that such a strategy of nanotechnology-mediated metal-ligand coordination and subsequent nontoxicity-to-toxicity transition of DA in tumor may provide a promising prospect for future chemotherapy design.