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Acute kidney injury (AKI) is a frequent and challenging clinical condition associated with high morbidity and mortality and represents a common complication in critically ill patients with COVID-19. In AKI, renal tubular epithelial cells (TECs) are a primary site of damage, and recovery from AKI depends on TEC plasticity. However, the molecular mechanisms underlying adaptation and maladaptation of TECs in AKI remain largely unclear. Here, our study of an autopsy cohort of patients with COVID-19 provided evidence that injury of TECs by myoglobin, released as a consequence of rhabdomyolysis, is a major pathophysiological mechanism for AKI in severe COVID-19. Analyses of human kidney biopsies, mouse models of myoglobinuric and gentamicin-induced AKI, and mouse kidney tubuloids showed that TEC injury resulted in activation of the glucocorticoid receptor by endogenous glucocorticoids, which aggravated tubular damage. The detrimental effect of endogenous glucocorticoids on injured TECs was exacerbated by the administration of a widely clinically used synthetic glucocorticoid, dexamethasone, as indicated by experiments in mouse models of myoglobinuric- and folic acid–induced AKI, human and mouse kidney tubuloids, and human kidney slice cultures. Mechanistically, studies in mouse models of AKI, mouse tubuloids, and human kidney slice cultures demonstrated that glucocorticoid receptor signaling in injured TECs orchestrated a maladaptive transcriptional program to hinder DNA repair, amplify injury-induced DNA double-strand break formation, and dampen mTOR activity and mitochondrial bioenergetics. This study identifies glucocorticoid receptor activation as a mechanism of epithelial maladaptation, which is functionally important for AKI. Editor's summary: Acute kidney injury (AKI) is a complication of critically ill patients with COVID-19. Dexamethasone is a synthetic glucocorticoid used to treat severe COVID-19. Zhou et al. combined data from patients who died in association with COVID-19, human tissue, and mouse models of AKI and found that renal tubular epithelial cell (TEC) damage from myoglobinuria resulted in glucocorticoid receptor activation and worse injury. Mice given myoglobinuric injury and dexamethasone treatment had exacerbated TEC damage. Human kidney slices and TEC organoids from both humans and mice corroborated this exacerbated damage. Inhibiting endogenous glucocorticoid production or inactivating the glucocorticoid receptor ameliorated TEC damage in these models. TEC damage was linked to DNA damage and mitochondrial impairment. These data suggest that glucocorticoid receptor activation aggravates renal injury. —Brandon Berry [ABSTRACT FROM AUTHOR]

Summary: Maize silk is a specialized type of stigma, covered with numerous papillae for pollen grain capture. However, the developmental process of stigmatic papillae and the underlying regulatory mechanisms have remained largely unknown.Here, we combined the cytological, genetic and molecular studies to demonstrate that three homologous genes ZmSPL10, ZmSPL14 and ZmSPL26 play a central role in promoting stigmatic papilla formation in maize.We show that their triple knockout mutants are nearly complete lack of stigmatic papilla, resulting in a severe reduction in kernel setting. Cellular examination reveals that stigmatic papilla is developed from a precursor cell, which is the smaller daughter cell resulting from asymmetric cell division of a silk epidermal cell. In situ hybridization shows that ZmSPL10, ZmSPL14 and their target genes SPI1, ZmPIN1b, ZmARF28 and ZmWOX3A are preferentially expressed in the precursor cells of stigmatic papillae. Moreover, ZmSPL10, ZmSPL14 and ZmSPL26 directly bind to the promoters of SPI1, ZmPIN1b, ZmARF28 and ZmWOX3A and promote their expression. Further, Zmwox3a knockout mutants display severe defects in stigmatic papilla formation and reduced seed setting.Collectively, our results demonstrate that ZmSPL10, ZmSPL14 and ZmSPL26 act together to promote stigmatic papilla development through regulating auxin signaling and ZmWOX3A expression. [ABSTRACT FROM AUTHOR]

Birds are sensitive to environmental changes and can drive range shifts rapidly due to their high mobility. Though previous studies have examined the associations between species traits and range shifts, whether species traits could still explain heterogeneity in shift directions remains poorly explored. Here, we compiled new bird records of China from 2000 to 2019 and analyzed species traits associated with apparent shift directions. We collected 350 provincial-level new records of birds belonging to 67 families of 22 orders. Of these, 32 are threatened, with 3 critically endangered, 11 endangered, and 18 vulnerable. Provinces in western China (i.e., Yunnan and Xizang) had relatively higher species richness of new recorded birds; this pattern was also reflected in the phylogenetic diversity we observed. In addition, provinces in northern China (i.e., Tianjin, Shandong, and Beijing) had relatively higher richness-controlled phylogenetic diversity. Phylogenetic overdispersion of new recorded bird communities was observed in 61.29% of provinces (19 of 31). The main shift directions indicated by new bird records were northward (with nearly 50% of birds moving NW, N and NE). Migration, hand-wing index (HWI), body mass, and range size are the four key factors that most significantly influence the shift directions in bird species, suggesting that bird movement toward newly suitable areas varies with species-specific traits. Together, these results demonstrate the importance of considering species ecological traits when predicting shift directions of birds. [ABSTRACT FROM AUTHOR]

Three pairs of enantiomers (1–3)—the new 12R-aloesol (1a) and two new fatty acids (2 and 3)—and one new natural product (4) together three known compounds (5–7) were isolated from a coral-reef-derived Streptomyces sp. SCSIO 66814. Their structures were determined through extensive spectroscopic analysis, chiral analysis, and single-crystal X-ray diffraction data. Compounds 2 and 3 were presumed to be intermediates for further generating homononactic acid (5) and nonactic acid, and the latter two molecules were able to act as precursors to form macrotetrolides with remarkable biological activity. The isolation of related precursors, compounds 2–5, provided more evidence to support the proposal of a plausible biosynthetic pathway for nonactic acid and its homologs. Additionally, (+)-1 exhibited a weak activity against DPPH radicals. [ABSTRACT FROM AUTHOR]

An ethyl acetate extract of a marine actinomycete strain, Nocardiopsis mentallicus SCSIO 53858, isolated from a deep-sea sediment sample in the South China Sea, exhibited anti-quorum-sensing (QS) activity against Chromobacterium violaceum CV026. Guided by the anti-QS activity, a novel active compound was isolated and purified from the extract and was identified as 2,3-dimethoxycinnamic acid (2,3-DCA) through spectral data analysis. At a concentration of 150 μg/mL, 2,3-DCA exhibited robust inhibitory effects on three QS-regulated traits of C. violaceum CV026: violacein production, swarming motility, and biofilm formation, with inhibition rates of 73.9%, 65.9%, and 37.8%, respectively. The quantitative reverse transcription polymerase chain reaction results indicated that 2,3-DCA can disrupt the QS system in C. violaceum CV026 by effectively suppressing the expression of QS-related genes, including cviR, vioA, vioB, and vioE. Molecular docking analysis revealed that 2,3-DCA hinders the QS system by competitively binding to the same binding pocket on the CviR receptor as the natural signal molecule N-hexanoyl-L-homoserine lactone. Collectively, these findings suggest that 2,3-DCA exhibits promising potential as an inhibitor of QS systems, providing a potential solution to the emerging problem of bacterial resistance. [ABSTRACT FROM AUTHOR]

Cinnamomum burmannii (Nees & T. Nees) Blume is a cinnamon species used for daily needs and as an herb in traditional medicine. This study was designed to determine the composition, antioxidant, and antimicrobial activity of essential oils (EOs) extracted from different organs of the plant. The gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) analysis revealed that the bark was dominated by 1-isopropyl-4,7-dimethyl-1,2,3,5,6,8a-hexahydronaphthalene (11.60%), γ-muurolene (8.79%), eucalyptol (7.66%), α-muurolene (7.37%), α-terpineol (6.65%), δ-selinene (6.42%), while endo-borneol (41.74 and 40.60%), caryophyllene (6.29 and 10.43%), and bornyl acetate (4.18 and 4.08%) were the primary components of branch and leaf oils. Additionally, a notable antioxidant power of the bark, branch and leaf essential oil was observed from the results of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging activity (0.03-0.05 mg/mL), antiradical power (ARP) (19.61-32.26), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity assay (0.40-0.75 mol/g), and ferric reducing antioxidant power (FRAP) (0.30-0.66 mg Fe2+/g). Branches and leaves had stronger antioxidant activity, and endo-borneol, bornyl acetate, humulene and cedrene were the main contributors to the antioxidant activity. Moreover, the bark showed notable inhibitory activity against Staphylococcus aureus, while the leaf oil had good antibacterial activity against Micrococcus luteus and Pseudomonas putida. These findings suggest that C. burmannii could be considered a potent source of natural nutraceutical uses. [ABSTRACT FROM AUTHOR]

Zanthoxylum nitidum (Roxb.) DC is a traditional Chinese herb from southern China and its 3–4‐year old roots are used in medicine. However, there is a scarcity of studies on the differences in the content of different regions of the roots, as well as comprehensive evaluations of Z. nitidum from the main areas of production in China. This study used ultra performance liquid chromatography, triple quadrupole tandem mass spectrometry, HPLC, and Fourier‐transform infrared spectroscopy to detect and identify the bioactive components from different parts and eight regions of 4‐year‐old roots of Z. nitidum. Our results revealed that the types and quantities of compounds extracted were similar in root bark and root wood, although the amount of alkaloids in the former was substantially higher. The contents of four alkaloids in samples from Guangdong were higher than those in Guangxi Province. Meanwhile, hierarchical cluster analysis and principal component analysis showed that the samples from different regions were effectively identified and evaluated based on alkaloids and other bioactive substances. Our findings have significant implications for Z. nitidum harvesting and usage, as well as for origin identification, quality evaluation, and sensible use of Z. nitidum resources. [ABSTRACT FROM AUTHOR]

For exploring structurally diverse metabolites and uniquely metabolic mechanisms, we systematically investigated the chemical constituents and putative biosynthesis of Janibacter sp. SCSIO 52865 derived from the deep-sea sediment based on the OSMAC strategy, molecular networking tool, in combination with bioinformatic analysis. As a result, one new diketopiperazine (1), along with seven known cyclodipeptides (2–8), trans-cinnamic acid (9), N-phenethylacetamide (10) and five fatty acids (11–15), was isolated from the ethyl acetate extract of SCSIO 52865. Their structures were elucidated by a combination of comprehensive spectroscopic analyses, Marfey's method and GC-MS analysis. Furthermore, the analysis of molecular networking revealed the presence of cyclodipeptides, and compound 1 was produced only under mBHI fermentation condition. Moreover, bioinformatic analysis suggested that compound 1 was closely related to four genes, namely jatA–D, encoding core non-ribosomal peptide synthetase and acetyltransferase. [ABSTRACT FROM AUTHOR]

Deep-sea sediment-derived bacterium may make full use of self-genes to produce more bioactive metabolites to adapt to extreme environment, resulting in the discovery of novel metabolites with unique structures and metabolic mechanisms. In the paper, we systematically investigated the metabolites in structurally diversity and their biosynthesis from the deep-sea sediment-derived bacterium Agrococcus sp. SCSIO 52902 based on OSMAC strategy, Molecular Networking tool, in combination with bioinformatic analysis. As a result, three new compounds and one new natural product, including 3R-OH-1,6-diene-cyclohexylacetic acid (1), linear tetradepsipeptide (2), N1,N5-di-p-(EE)-coumaroyl-N10-acetylspermidine (3) and furan fatty acid (4), together with nineteen known compounds (5–23) were isolated from the ethyl acetate extract of SCSIO 52902. Their structures were elucidated by comprehensive spectroscopic analysis, single-crystal X-ray diffraction, Marfey's method and chiral-phase HPLC analysis. Bioinformatic analysis revealed that compounds 1, 3, 9 and 13–22 were closely related to the shikimate pathway, and compound 5 was putatively produced by the OSB pathway instead of the PKS pathway. In addition, the result of cytotoxicity assay showed that compound 5 exhibited weak cytotoxic activity against the HL-60 cell line. [ABSTRACT FROM AUTHOR]

Strontium, a popular osteogenic component, has been incorporated into various types of orthopaedic biomaterials to enhance bone regeneration. Strontium performs dual effects in promoting bone formation and inhibiting bone resorption. Previous studies have focused on the effects of strontium ions (Sr2+) in regulating stem cell behavior to initiate regenerative capacity. However, its mechanisms for regulating the fate and homeostasis of stem cells have not been fully elucidated. In this study, the promotive effect of Sr2+ on the osteogenic differentiation of mesenchymal stem cells was confirmed both in vitro and in vivo. Interestingly, in response to Sr2+ treatment, stem cells performed asymmetric cell division to balance stemness maintenance and osteogenic differentiation. In initiating osteogenic differentiation, Sr2+ maintained more cells in the cell cycle by upregulating the population of S and G2/M phase cells, and this increase in the cell population contributed to enhanced osteogenic differentiation. The divided cells with different cell fates were observed, with one daughter cell maintained stemness, while the other committed to osteogenic lineage. Further investigation revealed that Sr2+ activated noncanonical Wnt signaling to regulate the expression and distribution of the Par complex, thus regulating cell division. As a result, the daughter cells committed to different cell fates due to the discriminately activation of osteogenic transcription factors caused by asymmetrically distributed Par3 and aPKC. The results of this study could facilitate the design of biomaterials for bone regeneration by providing a better understanding of cell fate determination regulated by strontium. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Secondary metabolites (SMs) of medicinal plants are the material basis of their clinically curative effects. They are also important indicators for evaluating the quality of medicinal materials. However, the synthesis and accumulation of SMs are very complex, which are affected by many factors including internal developmental genetic circuits (regulated gene, enzyme) and by external environment factors (light, temperature, water, salinity, etc.). Currently, lots of literatures focused on the effect of environmental factors on the synthesis and accumulation of SMs of medicinal plants, the effect of the developmental growth and genetic factors on the synthesis and accumulation of SMs still lack systematic classification and summary. Here, we have given the review base on our previous works on the morphological development of medicinal plants and their secondary metabolites, and systematically outlined the literature reports how different environmental factors affected the synthesis and accumulation of SMs. The results of our reviews can know how developmental and environmental factors qualitatively and quantitatively influence SMs of medicinal plants and how these can be integrated as tools to quality control, as well as on the improvement of clinical curative effects by altering their genomes, and/or growth conditions. • The secondary metabolites (SMs) of plant can be especially affected by developmental and environmental factors. • The review reveal the dynamic accumulation of SMs in medicinal plants. • Developmental and environmental factors has influence on the expression of SMs biosynthesis genes. • The review suggest regulation at post-transcriptional/translational levels on SMs. [ABSTRACT FROM AUTHOR]

In order to acquire a tetracalcium phosphate/magnesium phosphate (TTCP/MPC) composite bone cement that combines the excellent bioactivity of TTCP and high mechanical strength of MPC, the cement was made and the compressive strength, phase composition of hardened cement, degradation in vitro, and tissue responses in vivo by implantation of TTCP/MPC in bone defect of rabbits were investigated. The results showed that TTCP/MPC was with a markedly better mechanical property than MPC. Moreover, compared with MPC, TTCP/MPC showed significantly delayed degradability in simulated body fluid. To investigate the in vivo biocompatibility and osteogenesis, the TTCP/MPC samples were implanted into bone defects in rabbits. Histological evaluation displayed that the introduction of TTCP into MPC enhanced the efficiency of new bone formation. TTCP/MPC also showed good biocompatibility, biodegradability and osteoconductivity with host bone in vivo. The results suggested that TTCP/MPC meets the basic requirements of bone tissue engineering, has an obvious clinical advantage over MPC and is promising to be applied in orthopedic, reconstructive and maxillofacial surgery. [ABSTRACT FROM AUTHOR]

Hybrid snakehead fish ( Channa maculata ♀ ×  Channa argus ♂), a new species used in freshwater aquaculture in China, is the common host of an epizootic bacterial infection by Nocardia seriolae . However, the information on the functions and mechanisms of hybrid snakehead immune pathways with the N . seriolae infection is limited. Thus, the peripheral blood lymphocytes from hybrid snakehead were used for transcriptome analysis to understand the host immune response after challenge with N . seriolae . A total of 49,839,332 and 50,059,283 raw reads were obtained from the N . seriolae -challenged group (Ns group) and phosphate-buffered saline control group (Ctr group), respectively. The 75.50% and 74.25% reads from the Ns and Ctr groups were matched to reference genomic sequence after cleaning the raw reads, respectively. Additionally, there were 2892 significant differentially expressed genes (DEGs) among the 17,196 expressed genes between the Ns and Ctr groups, including 1387 upregulated and 1505 downregulated genes. All the DEGs were classified into three gene ontology categories, and 2502 DEGs had significant matches, which were allocated to 246 Kyoto Encyclopedia of Genes and Genomes pathways. Immune-related genes were detected from immune system pathways among the top 20 enriched pathways. Moreover, the regulation of several observed effective genes was confirmed by real-time quantitative polymerase chain reaction. Altogether, this study offers deep-sequence data of hybrid snakehead peripheral blood lymphocyte via transcriptome analysis and lays the foundation for further study on the immunogenetics of hybrid snakehead. Moreover, it provides insights into the pathogenic mechanism of N . seriolae , facilitating the prevention and treatment of fish nocardiosis. [ABSTRACT FROM AUTHOR]

Abstract: To solve the problem of poor water resistance and restricted usage of magnesium phosphate cement, the cement prepared by NaH2PO4 and NH4H2PO4 was modified via chitosan, and the modification mechanism was also explored. The results showed that the optimum molar ratio of NaH2PO4: NH4H2PO4 was 2:3. Upon setting the chitosan content of wt.1%, the mechanical strength of the resulting cements after 28 days was 42 MPa. After water immersion, the percentage of the lost mechanical strength of cements and mass loss was smaller than those in the control group. Free amino group on the molecular chain of chitosan could react with Mg2+ ions to form complexes. Interconnected polymer network structure was formed in magnesium phosphate bone cement paste. Magnesium phosphate bone cement had hydration products with Mg2+ ions as nucleation sites, which further gradually formed a network structure, indicating that chitosan could improve the water resistance of magnesium phosphate bone cements. [ABSTRACT FROM AUTHOR]

Uncontrolled hemorrhage is the main cause of death in many situations. Substantial efforts have been focused on developing more efficient hemostatic agents. Meanwhile, their safety is also critical for their application. Chitosan is an attractive natural polymer and has been widely investigated for hemostatic application. This study sought to incorporate poly(vinyl alcohol) (PVA) components and fabricate them into monodisperse millimeter-sized spheres to improve efficiency and safety. Chitosan–PVA spheres were fabricated by electrospraying and ionotropic gelation. The millimeter-sized spheres were obtained by adjusting the electrospraying parameters, including applied voltage, working distance, feed rate, polymer solution and component content. The morphology, chemical structure and thermostability of the spheres were characterized by variable pressure scanning electron microscopy (VP-SEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). These spheres showed narrow size distribution and good biocompatibility. The hemostatic effect was evaluated both in vitro and in vivo using a blood coagulation timing experiment and a rat liver hemorrhaging model, and chitosan50–PVA50 spheres showed the best effect. PVA contributed to the high swelling degree of the spheres and the enhanced hemostatic effect. These spheres also significantly reduced thromboembolus formation in controlling femoral artery bleeding compared with chitosan powder, providing an efficient and safe hemostasis agent. [ABSTRACT FROM AUTHOR]

Polyploidization is an effective method to achieve a higher yield of secondary metabolism active ingredients in medicinal plants. Polyphenols are the main active substances that contribute to the antioxidant activity of Lonicera japonica . For studying on the effect of chromosome doubling and harvest time on the dynamic accumulation of the main active substances and antioxidant capabilities of L. japonica , the polyphenol composition contents (7 phenolic acids and 3 flavonoids) and the antioxidant capacity in buds and flowers of diploid and tetraploid L. japonica at six different growth stages were determined by HPLC-DAD and three common antioxidant assays (FRAP, OH RSC and DPPH ARP), and the correlation between the dynamic accumulation of the polyphenol components and antioxidant capacity was also analyzed in current research. The results indicated that the content of the most determined phenolic acids and flavonoids and the antioxidant capacity in most of the growth stages from tetraploid plants were significantly higher than those in the diploid plants. Furthermore, the changes in the antioxidant activity presented a significant positive correlation with the variations in the chlorogenic acid, rutin, hyperoside, luteoloside in the two ploidy levels of L. japonica plants. The higher yields of chlorogenic acid (158.97, 164.00, 199.85 mg), luteoloside (5.44, 4.03, 6.31 mg), hyperoside (1.15, 1.06, 1.30 mg) and total flavonoids (9.87, 8.67, 11.10 mg) from 100 buds or flowers in tetraploid plants occurred during the S3–S5 stages, and these stages also exhibited higher antioxidant activities. Therefore, the stages of S3–S5 are recommended as the best time for harvesting high-yield, high-quality tetraploid Flos Lonicerae Japonicae. [ABSTRACT FROM AUTHOR]

In this work, we investigate the enhanced mechanical properties of nano-hydroxyapatite/polyamide 66 (nHA/PA66) composites reinforced with multi-walled carbon nanotubes (MWCNTs) by means of the blending method. The MWCNTs–nHA/PA66 composites were characterized by various techniques, and the obtained results indicated that the MWCNTs were evenly distributed in the composite and that good interfacial bonding was formed between MWCNTs and PA66. The addition of MWCNTs improved the crystallinity of PA66, while it had little or no effect either on the composition or on the crystal structure of the composites. Moreover, the addition of MWCNTs in nHA/PA66 significantly improved the mechanical strength, and the tensile and compressive strengths attained maximum values of 90.3 and 126.8 MPa, respectively, with the addition of 0.1 wt% MWCNTs, whereas the bending strength attained a maximum value of 105.5 MPa with the addition of 0.05 wt% MWCNTs. Finally, L929 cells co-cultured with the MWCNTs-nHA/PA66 composite exhibited comparatively uninhibited cell growth, indicating that the addition of MWCNTs had negligible effect on the cytocompatibility of the original nHA/PA66 composite. [ABSTRACT FROM PUBLISHER]

Hydroxyapatite and strontium-substituted hydroxyapatite nanoparticles (n-HA and Sr-HA) were prepared by microwave-assisted solution synthesis with aqueous solutions of various Sr/(SrCa) molar ratios ranging from 0% to 15%. The structural properties of the hydroxyapatite powders were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy and Raman spectra, field emission scanning electron microscopy coupled with energy dispersive X-ray spectrometry and transmission electron microscopy. The results confirmed that strontium ions had been incorporated into the hydroxyapatite lattice. The synthetic n-HA and Sr-HA nanocrystalline consisted of hydroxyapatite crystalline phase with hexagonal structure, and the particle size was 30-40 × 60-70nm and 40-50 × 70-80nm, respectively. The calcined HA particle size ranged from about 120nm to 150nm, the calcined Sr-HA products were composed of spherical aggregates with a size of about 70-100nm. The incorporation of Sr ions lead to the formation of vacancies in the crystal structure of the HA. The results indicated that the strontium substitution did not change the crystal structures. More Sr resulted in less calcined crystallites and formed agglomerates owing to the size effect. Strontium-substituted hydroxyapatite was synthesized by microwave-assisted solution. The incorporation of Sr ions led to the formation of vacancies in the crystal structure of HA, and did not change the crystal structures. The synthetic n-HA and Sr-HA nanocrystalline consisted of hydroxyapatite crystalline phase with hexagonal structure. The calcined Sr-HA products were composed of nanoscale spherical aggregates, which indicated that the doping of Sr2+ in apatite lattice destroyed the long range order arrangement of atoms, thus affecting the thermal stability. [ABSTRACT FROM AUTHOR]

The combination of nano-hydroxyapatite (n-HA) and polypropylene carbonate (PPC) was used to make a composite materials by a coprecipitation method. The physical and chemical properties of the composite were tested. Scanning electron microscope (SEM) observation indicated that the biomimetic n-HA crystals were uniformly distributed in the polymer matrix. As the n-HA content increased in the composite, the fracture mechanism of the composites changes from gliding fracture to gliding and brittle fracture. Furthermore, the chemical interaction between inorganic n-HA and polypropylene carbonate was also investigated and discussed in detail. The hydrogen bonds might be formed between –OH/CO 3 2 − of n-HA crystal and the ester group (–COO–) of PPC. The tensile strength of n-HA/PPC (40/60) was similar to that of the cancellous bone, and reached ca 58 MPa. The osteoblasts were cultured for up to 7 days, and then the adhesion and proliferation of osteoblasts were measured by Methyl thiazolyl tetrazolium (MTT) colorimetry assay and SEM. The cells proliferated, grew normally in fusiform shape and well attached. The in vitro test confirmed that the n-HA/PPC composites were biocompatible and showed undetectable negative effect on osteoblasts. In vivo implantation of the composite in New Zealand white rabbits was performed. It can stimulate the growth of a new bone, and at the same time the material begins to degrade. These results suggested that the composite may be suitable for the reparation or replacement of bone defects and possessed the potential for clinical applications. [ABSTRACT FROM AUTHOR]

Incorporation of small reactive moieties, the reactivity of which depends on externally imposed load (so-called mechanophores) into polymer chains offers access to a broad range of stress-responsive materials. Here, we report that polymers incorporating spirothiopyran (STP) manifest both green mechanochromism and load-induced addition reactions in solution and solid. Stretching a macromolecule containing colorless STP converts it into green thiomerocyanine (TMC), the mechanically activated thiolate moiety of which undergoes rapid thiol-ene click reactions with certain reactive C=C bonds to form a graft or a cross-link. The unique dual mechanochemical response of STP makes it of potentially great utility both for the design of new stress-responsive materials and for fundamental studies in polymer physics, for example, the dynamics of physical and mechanochemical remodeling of loaded materials. [ABSTRACT FROM AUTHOR]