Zinc (Zn) alloys provide a new generation for orthopedic applications due to their essential physiological effects and promising degradation properties. However, excessive release of Zn ions (Zn
) ...during degradation and the severe inflammatory microenvironment are not conducive to osseointegration, which is determined by the characteristics of the implant surface. Therefore, it is essential to modulate the release rate of Zn alloys by surface modification technology and endow them with anti-inflammatory and osteogenic effects. In this study, two kinds of phosphate chemical conversion (PCC) coatings with different compositions and morphological structures are prepared, namely Zn-P (with disk-like crystals) and Ca-Zn-P (with lamellar crystals). Although all the PCC-coated Zn implants have low cytotoxicity, Ca-Zn-P show better osteoimmunomodulation effects in several aspects: the induction of the M2-phenotype macrophage polarization and thus promotion of osteogenesis in vitro; the regulation of the bone immune microenvironment which is conducive to tissue regeneration and osseointegration in vivo; and the release of ions (through PI3K/AKT and Wnt signaling pathways) and the morphological structures (through RhoGTPase signaling pathways) act as possible mechanisms of M2 polarization. The Ca-Zn-P coating can be considered to provide new insights into bone immunomodulation and osseointegration.
Switchable copolymerization of oxygenated heterocycle mixtures by a single catalytic system has been proved to be a promising approach to sequence‐controlled block copolymers. However, there are ...still big challenges in one‐step synthesis of multiblock copolymers containing unsaturated polyester blocks from maleic anhydride, epoxides, and lactone mixtures. Herein, a switchable pathway for polylactide‐b‐poly(MAH‐alt‐epoxide)‐b‐polylactide block copolymers is established. The excellent chemoselectivity in multicomponent copolymerization is achieved by bipyridine bisphenolate aluminum complexes that can induce an obvious kinetic differentiation between ring‐opening copolymerization of maleic anhydride/epoxides and ring‐opening polymerization of lactide. The scope of the epoxide for switchable copolymerization is explored and it is found that the steric hindrance of the substituents on epoxide significantly influences the formation of block copolymers. Block copolymers with various sequential and topological structures can be easily prepared by exquisite selection of different initiators. Furthermore, it is demonstrated that the conversion of cis‐maleate units in the block copolyester could be completely converted to trans‐fumarate units by isomerization without chain degradation, cross‐linking, and chain scrambling.
The synthesis of sequence‐controlled block copolymers with unsaturated polyester sequence from switchable copolymerization of maleic anhydride/epoxide/lactone mixtures is reported. The cis‐maleate units in the block copolyester can be completely converted to trans‐fumarate units by isomerization without chain degradation, cross‐linking, and chain scrambling.
Abstract
Transposons are known to participate in tissue aging, but their effects on aged stem cells remain unclear. Here, we report that in the
Drosophila
ovarian germline stem cell (GSC) niche, ...aging-related reductions in expression of Piwi (a transposon silencer) derepress retrotransposons and cause GSC loss. Suppression of Piwi expression in the young niche mimics the aged niche, causing retrotransposon depression and coincident activation of Toll-mediated signaling, which promotes Glycogen synthase kinase 3 activity to degrade β-catenin. Disruption of β-catenin-E-cadherin-mediated GSC anchorage then results in GSC loss. Knocking down
gypsy
(a highly active retrotransposon) or
toll
, or inhibiting reverse transcription in the
piwi
-deficient niche, suppresses GSK3 activity and β-catenin degradation, restoring GSC-niche attachment. This retrotransposon-mediated impairment of aged stem cell maintenance may have relevance in many tissues, and could represent a viable therapeutic target for aging-related tissue degeneration.
Circulating microRNAs are promising biomarkers for non‐invasive testing and dynamic monitoring in cancer patients. However, no consensus exists regarding the normalization of circulating microRNAs in ...the quantification, making the results incomparable. We investigated global circulating microRNA profiles to identify a stable endogenous control for quantifying circulating microRNAs using three cohorts (n = 544), including 168 control individuals (healthy subjects and those with chronic hepatitis B and cirrhosis) and 376 cancer patients (hepatocellular, colorectal, lung, esophageal, gastric, renal, prostate, and breast cancer patients). GeNorm, NormFinder, and coefficient of variability (CV) were used to select the most stable endogenous control, whereas Ingenuity Pathway Analysis (IPA) was adopted to explore its signaling pathways. Seven candidates (miR‐1225‐3p, miR‐1228, miR‐30d, miR‐939, miR‐940, miR‐188‐5p, and miR‐134) from microarray analysis and four commonly used controls (miR‐16, miR‐223, let‐7a, and RNU6B) from literature were subjected to real‐time quantitative reverse transcription‐polymerase chain reaction validation using independent cohorts. MiR‐1228 (CV = 5.4%) with minimum M value and S value presented as the most stable endogenous control across eight cancer types and three controls. IPA showed miR‐1228 to be involved extensively in metabolism‐related signal pathways and organ morphology, implying that miR‐1228 functions as a housekeeping gene. Functional network analysis found that “hematological system development” was on the list of the top networks that associate with miR‐1228, implying that miR‐1228 plays an important role in the hematological system. The results explained the steady expression of miR‐1228 in the blood. In conclusion, miR‐1228 is a promising stable endogenous control for quantifying circulating microRNAs in cancer patients.
What's new?
While circulating microRNAs (miRNAs) are promising cancer biomarkers, a standard control for the normalization of serum/plasma miRNA levels is yet to be established. Without such a control, data from different studies and different cancers remains incomparable. Here, analysis of global circulating microRNA profiles in healthy individuals and cancer patients suggests that miR‐1228, one of seven candidates identified from microarray analysis, is a stable endogenous control for the quantification of circulating miRNAs in cancer patients. MiR‐1228 allows for the comparison of circulating miRNA expressions in the same cancer across different studies and in different cancers of the same study.
•Accelerated corrosion of the longitudinal reinforcement and stirrup was carried out by the electroosmosis-constant current-dry wet cycle method.•The effects of the corrosion degree, stirrup spacing ...and cover thickness parameters on the bond performance were analyzed by pull-out tests.•A modified bond-slip constitutive model that considers the corrosion of longitudinal bars and stirrups was proposed.
The corrosion of longitudinal rebar and stirrups will cause serious degradation of the bond performance between steel bars and concrete. To investigate the impact of both longitudinal rebar and stirrup corrosion on the bond behavior, 35 reinforced concrete (RC) pull-out specimens were subjected to accelerated corrosion tests with electroosmosis/constant current/dry-wet cycling and pull-out tests. The influence laws of the degree of corrosion of the longitudinal reinforcement, degree of corrosion of the stirrups, cover thickness, stirrup spacing and longitudinal reinforcement diameter on the bond performance were also investigated. The bond behavior between corroded steel bars and concrete was analyzed from the aspects of corrosion form, failure mode and bond strength. Subsequently, based on the experimental data, a modified bond-slip constitutive model that considers the design parameters, stirrup corrosion and longitudinal rebar corrosion was built and verified. The modified bond-slip constitutive model was applied to the cohesive element to establish a finite element model of the corroded pull-out specimens, and additional parameters were analyzed.
Magnesium phosphate (MgP) has garnered growing interest in hard tissue replacement processes due to having similar biological characteristics to calcium phosphate (CaP). In this study, an MgP coating ...with the newberyite (MgHPO
·3H
O) was prepared on the surface of pure titanium (Ti) using the phosphate chemical conversion (PCC) method. The influence of reaction temperature on the phase composition, microstructure, and properties of coatings was systematically researched with the use of an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a laser scanning confocal microscope (LSCM), a contact angle goniometer, and a tensile testing machine. The formation mechanism of MgP coating on Ti was also explored. In addition, the corrosion resistance of the coatings on Ti was researched by assessing the electrochemical behavior in 0.9% NaCl solution using an electrochemical workstation. The results showed that temperature did not obviously affect the phase composition of the MgP coatings, but affected the growth and nucleation of newberyite crystals. In addition, an increase in reaction temperature had a great impact on properties including surface roughness, thickness, bonding strength, and corrosion resistance. Higher reaction temperatures resulted in more continuous MgP, larger grain size, higher density, and better corrosion resistance.
Central nervous system (CNS) disorders play a major impact on individual lives and place a severe strain on health care resources. Convolvulaceae is a family comprising approximately 1,600–1,700 ...species grouped in 55–60 genera, and many species are reported to have an effect on CNS functions. A systematic review of the literature studies was carried out to summarize available evidences on Convolvulaceae plants with CNS efficacies. This review is based on various data sources such as Google Scholar, Web of Science, Scopus, PubMed, and Wanfang Data. A total of 200 related articles were included in this review. According to the research result, 54 Convolvulaceae species are suggested to display CNS efficacies historically, and 46 species have been evaluated for their CNS efficacies. In addition, 67 compounds from 16 Convolvulaceae species are recognized to possess CNS efficacies. Despite great progress made through pharmacology and phytochemistry studies on CNS active Convolvulaceae species, more exploratory research is needed to gain a better understanding of the CNS efficacies of this plant family.
Aims
This study evaluated the control effect of the endophytic fungus Phomopsis liquidambaris B3 against rice bakanae disease (RBD) caused by Fusarium proliferatum and the disease control result of ...different inoculation times of beneficial micro‐organisms.
Methods and Results
Rice seedlings preinoculated, coinoculated and noninoculated with B3 were exposed to F. proliferatum stress and grown under controlled conditions. Greenhouse experimental results showed that rice preinoculation with B3 significantly reduced rice bakanae disease by 21.45%, inhibited the colonization of F. proliferatum, increased defence‐related enzyme activities, upregulated the expression of defence genes and promoted plant photosynthesis. However, bakanae disease in rice coinoculation with B3 increased by 11.45%, resulted in excessive reactive oxygen species (ROS) bursts and plant cell death.
Conclusions
Preinoculation with the endophytic fungus P. liquidambaris B3 significantly reduced rice bakanae disease by triggering the SA‐dependent defence pathways of plants, and promoted plant growth. However, coinoculatiton with P. liquidambaris B3 activated excessive defence responses, resulting in plants cell death and aggravation of bakanae disease.
Significance and Impact of the Study
This study indicated that P. liquidambaris B3 was an effective method for agricultural control against rice bakanae disease caused by F. proliferatum, and provides an experimental basis for the development of sustainable endophytic fungal resources to effectively control plant diseases caused by pathogenic fungi, and suggests that precise application of beneficial micro‐organisms may be become a key factor in farmland crop disease management.
Alkaline hydrolysis of the resin glycoside fraction of the whole plants of Convolvulus arvensis gave two new glycosidic acids, named arvensic acids K and L (1 and 2). Their structures were ...characterized on the basis of spectroscopic data as well as chemical evidence. They possessed a same pentasaccharide chain, composed of one D-fucose, three D-glucose and one L-rhamnose units. The aglycone of compound 1 was identified to be rarely existing 11S-hydroxyheptadecanoic acid, while compound 2 possessed 11S-hydroxyhexadecanoic acid as the aglycone. Their cytotoxic and anti-migration activities were also evaluated.
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