In recent decades, collagen is one of the most versatile biomaterials used in biomedical applications, mostly due to its biomimetic and structural composition in the extracellular matrix (ECM). ...Several attempts are proposed for designing innovative collagen‐based biomaterials and applying them in tissue regeneration. The regeneration of different tissues is prompted by different types and diverse physical forms of collagen‐based biomaterials prepared by various methods. Based on such concepts, the source, structure, and classification of collagen are briefly introduced in this review. Here, the commonly used physical forms and modification methods of collagen‐based biomaterials are reviewed, including hydrogels, scaffolds, and microspheres, followed by their applications in the regeneration of tissues and organs. Important proof‐of‐concept examples are described to demonstrate the outcomes on material characteristics, cellular reactions, and tissue regeneration. A concise assessment of the limitations that still exist and the developing trends in the future of collagen‐based biomaterials are put forward.
In this review, an overview of the different physical forms of collagen‐based biomaterials is provided and the corresponding commonly used fabrication methods as well as advanced technologies in detail followed by examples of their applications in the regeneration of tissues and organs are discussed. The limitations and potential development directions are also listed at the end.
We report the first dark matter search results using the commissioning data from PandaX-4T. Using a time projection chamber with 3.7 tonne of liquid xenon target and an exposure of 0.63 tonne·year, ...1058 candidate events are identified within an approximate nuclear recoil energy window between 5 and 100 keV. No significant excess over background is observed. Our data set a stringent limit to the dark matter-nucleon spin-independent interactions, with a lowest excluded cross section (90% C.L.) of 3.8×10^{-47} cm^{2} at a dark matter mass of 40 GeV/c^{2}.
Both plants and animals possess analogous tissues containing hierarchical networks of pores, with pore size ratios that have evolved to maximize mass transport and rates of reactions. The underlying ...physical principles of this optimized hierarchical design are embodied in Murray's law. However, we are yet to realize the benefit of mimicking nature's Murray networks in synthetic materials due to the challenges in fabricating vascularized structures. Here we emulate optimum natural systems following Murray's law using a bottom-up approach. Such bio-inspired materials, whose pore sizes decrease across multiple scales and finally terminate in size-invariant units like plant stems, leaf veins and vascular and respiratory systems provide hierarchical branching and precise diameter ratios for connecting multi-scale pores from macro to micro levels. Our Murray material mimics enable highly enhanced mass exchange and transfer in liquid-solid, gas-solid and electrochemical reactions and exhibit enhanced performance in photocatalysis, gas sensing and as Li-ion battery electrodes.
Hypoxic-ischemic (HI) brain injury is a leading cause of acute mortality and chronic disability in newborns. Current evidence shows that cerebral microvascular response and compromised blood-brain ...barrier (BBB) integrity occur rapidly and could primarily be responsible for the brain injury observed in many infants with HI brain injury. MicroRNAs (miRNAs) are a type of highly conserved non-coding RNAs (ncRNAs), which consist of 21-25 nucleotides in length and usually lead to suppression of target gene expression. Growing evidence has revealed that brainenriched miRNAs act as versatile regulators of BBB dysfunctions in various neurological disorders including neonatal HI brain injury. In the present review, we summarize the current findings regarding the role of miRNAs in BBB impairment after hypoxia/ischemia brain injury. Specifically, we focus on the recent progress of miRNAs in the pathologies of neonatal HI brain injury. These findings can not only deepen our understanding of the role of miRNAs in BBB impairment in HI brain injury, but also provide insight into the development of new therapeutic strategies for preservation of BBB integrity under pathological conditions.
Irisin deficiency disturbs bone metabolism Zhu, Xiaofang; Li, Xiangfen; Wang, Xiaoxuan ...
Journal of cellular physiology,
January 2021, Letnik:
236, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Balancing the process of bone formation and resorption is important in the maintenance of healthy bone. Therefore, the discovery of novel factors that can regulate bone metabolism remains needed. ...Irisin is a newly identified hormone‐like peptide. Recent studies have reported the involvement of irisin in many physiological and pathological conditions with bone mineral density changes, including osteopenia and osteoporotic fractures. In this study, we generated the first line of Osx‐Cre:FNDC5/irisin KO mice, in which FNDC5/irisin was specifically deleted in the osteoblast lineage. Gene and protein expressions of irisin were remarkably decreased in bones but no significant differences in other tissues were observed in knockout mice. FNDC5/irisin deficient mice showed a lower bone density and significantly delayed bone development and mineralization from early‐stage to adulthood. Our phenotypical analysis exhibited decreased osteoblast‐related gene expression and increased osteoclast‐related gene expression in bone tissues, and reduced adipose tissue browning due to bone‐born irisin deletion. By harvesting and culturing MSCs from the knockout mice, we found that osteoblastogenesis was inhibited and osteoclastogenesis was increased. By using irisin stimulated wildtype primary cells as a gain‐of‐function model, we further revealed the effects and mechanisms of irisin on promoting osteogenesis and inhibiting osteoclastogenesis in vitro. In addition, positive effects of exercise, including bone strength enhancement and body weight loss were remarkably weakened due to irisin deficiency. Interestingly, these changes can be rescued by supplemental administration of recombinant irisin during exercise. Our study indicates that irisin plays an important role in bone metabolism and the crosstalk between bone and adipose tissue. Irisin represents a potential molecule for the prevention and treatment of bone metabolic diseases.
In this study, we generated bone‐born irisin deficiency mice and studied the effect of bone‐born irisin on bone mineralization and bone metabolism in vivo and in vitro. Our study indicates that irisin plays an important role in bone metabolism and the crosstalk between bone and adipose tissue. Irisin represents a potential molecule for the prevention and treatment of bone metabolic diseases.
Neonatal hypoxic-ischemic (HI) brain injury is a leading cause of acute mortality and chronic disability in newborns. Our previous studies demonstrated that HI insult significantly increased ...microRNA-210 (miR-210) in the brain of rat pups and inhibition of brain endogenous miR-210 by its inhibitor (LNA) provided neuroprotective effect in HI-induced brain injury. However, the molecular mechanisms underpinning this neuroprotection remain unclear.
We made a neonatal HI brain injury model in mouse pups of postnatal day 7 to uncover the mechanism of miR-210 in targeting the ten eleven translocation (TET) methylcytosine dioxygenase 2 that is a transcriptional suppressor of pro-inflammatory cytokine genes in the neonatal brain. TET2 silencing RNA was used to evaluate the role of TET2 in the neonatal HI-induced pro-inflammatory response and brain injury. MiR-210 mimic and inhibitor (LNA) were delivered into the brain of mouse pups to study the regulation of miR-210 on the expression of TET2. Luciferase reporter gene assay was performed to validate the direct binding of miR-210 to the 3' untranslated region of the TET2 transcript. Furthermore, BV2 mouse microglia cell line was employed to confirm the role of miR-210-TET2 axis in regulating pro-inflammatory response in microglia. Post-assays included chromatin immunoprecipitation (ChIP) assay, co-immunoprecipitation, RT-PCR, brain infarct assay, and neurobehavioral test. Student's t test or one-way ANOVA was used for statistical analysis.
HI insult significantly upregulated miR-210, downregulated TET2 protein abundance, and increased NF-κB subunit p65 acetylation level and its DNA binding capacity to the interleukin 1 beta (IL-1β) promoter in the brain of mouse pups. Inhibition of miR-210 rescued TET2 protein level from HI insult and miR-210 mimic decreased TET2 protein level in the brain of mouse pups, suggesting that TET2 is a functional target of miR-210. The co-immunoprecipitation was performed to reveal the role of TET2 in HI-induced inflammatory response in the neonatal brain. The result showed that TET2 interacted with NF-κB subunit p65 and histone deacetylase 3 (HDAC3), a co-repressor of gene transcription. Furthermore, TET2 knockdown increased transcriptional activity of acetyl-p65 on IL-1β gene in the neonatal brain and enhanced HI-induced upregulation of acetyl-p65 level and pro-inflammatory cytokine expression. Of importance, TET2 knockdown exacerbated brain infarct size and neurological deficits and counteracted the neuroprotective effect of miR-210 inhibition. Finally, the in vitro results demonstrated that the miR-210-TET2 axis regulated pro-inflammatory response in BV2 mouse microglia cell line.
The miR-210-TET2 axis regulates pro-inflammatory cytokine expression in microglia, contributing to neonatal HI brain injury.
We report constraints on light dark matter through its interactions with shell electrons in the PandaX-II liquid xenon detector with a total 46.9 tonnes / day exposure. To effectively search for ...these very low energy electron recoils, ionization-only signals are selected from the data. 1821 candidates are identified within an ionization signal range between 50 and 75 photoelectrons, corresponding to a mean electronic recoil energy from 0.08 to 0.15 keV. The 90% C.L. exclusion limit on the scattering cross section between the dark matter and electron is calculated with systematic uncertainties properly taken into account. Under the assumption of point interaction, we provide the world's most stringent limit within the dark matter mass range from 15 to 30 MeV / c2, with the corresponding cross section from 2.5 × 10−37 to 3.1 × 10−38 cm2.
Cerebral blood flow (CBF) acutely reduces in neonatal hypoxic-ischemic encephalopathy (HIE). Clinic studies have reported that severe CBF impairment can predict HIE outcomes in neonates. Herein, the ...present study uses a non-invasive 3D ultrasound imaging approach to evaluate the changes of CBF after HI insult, and explores the correlation between CBF alterations and HI-induced brain infarct in mouse pups. The neonatal HI brain injury was induced in postnatal day 7 mouse pups using the Rice-Vannucci model. Non-invasive 3D ultrasound imaging was conducted to image CBF changes with multiple frequencies on mouse pups before common carotid artery (CCA) ligation, immediately after ligation, and 0 or 24 hours after HI. Vascularity ratio of the ipsilateral hemisphere was acutely reduced after unilateral ligation of the CCA alone or in combination with hypoxia, and partially restored at 24 hours after HI. Moreover, regression analysis showed that the vascularity ratio of ipsilateral hemisphere was moderately correlated with brain infarct size 24 hours after HI, indicating that CBF reduction contributes to of HI brain injury. To further verify the association between CBF and HI-induced brain injury, a neuropeptide C-type natriuretic peptide (CNP) or PBS was intranasally administrated to the brain of mouse pups one hour after HI insult. Brain infarction, CBF imaging and long-term neurobehavioral tests were conducted. The result showed that intranasal administration of CNP preserved ipsilateral CBF, reduced the infarct size, and improved neurological function after HI brain injury. Our findings suggest that CBF alteration is an indicator for neonatal HI brain injury, and 3D ultrasound imaging is a useful non-invasive approach for assessment of HI brain injury in mouse model.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Through comparing the photocatalytic performance of microscale ZnO, nano ZnO, and Degussa P25 titania (P25), it was found that the microscale ZnO exhibited 2.6−35.7 times higher photocatalytic ...activity for the photodegradation of various dye pollutants than P25 under both UV−visible and visible irradiation and showed much better photostability than the nano ZnO. The photocatalysts were characterized with XRD, Raman, BET, DRUV−vis, adsorption of dye, photoelectrochemical measurement, and PL. The much higher photocataltyic activity of the microscale ZnO than P25 under UV−visible irradiation is attributed to the higher efficiency of generation, mobility, and separation of photoinduced electrons and holes. The much higher visible photocataltyic activity of the microscale ZnO than P25 is due to the higher photosensitization efficiency of electron transfer from an excited dye to the conduction band of the microscale ZnO than that of P25. The much better photostability of the microscale ZnO than the nano ZnO is due to its better crystallinity and lower defects. The photostability of the microscale ZnO is greatly improved by the surface modification of ZnO with a small amount of TiO2. On the basis of the excellent photocatalytic performance of the microscale ZnO and TiO2-modified ZnO, a novel device of coupling photodegradation with light-to-electricity conversion was developed, which is a promising candidate for the photocatalytic removal of dye pollutants and a renewable energy source.
We report a novel search for the cosmic-ray boosted dark matter using the 100 tonne·day full dataset of the PandaX-II detector located at the China Jinping Underground Laboratory. With the extra ...energy gained from the cosmic rays, sub-GeV dark matter particles can produce visible recoil signals in the detector. The diurnal modulations in rate and energy spectrum are utilized to further enhance the signal sensitivity. Our result excludes the dark matter-nucleon elastic scattering cross section between 10^{-31} and 10^{-28} cm^{2} for dark matter masses from 0.1 MeV/c^{2} to 0.1 GeV/c^{2}, with a large parameter space previously unexplored by experimental collaborations.
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