Amino-Functionalized Lotus Stem Hydrochar for Rapid Adsorption and In Situ Detoxification of Cr(VI) from Water.

The development of low-cost, efficient, and environmentally friendly adsorbents is the key to highly toxic hexavalent chromium [Cr(VI)] removal by adsorption. In this paper, amino-functionalized lotus stem hydrochar (ALSHC) was prepared from an agricultural waste lotus stem (LS) for the adsorption removal of Cr(VI) from water. The effects of the initial Cr(VI) concentration, contact time, temperature, coexisting anions, and reusability of ALSHC on Cr(VI) removal were examined in detail. The adsorption mechanism was further discussed by investigating the impact of the solution's initial pH, the relation between the pH change in solution and Cr(VI) removal during the process, the changes of chromium (Cr) species in solution and on ALSHC during adsorption, and the XPS characterization. The results demonstrated that ALSHC effectively removed Cr(VI) from water with rapid adsorption (the removal rate reached 80.90% in only 10 min) and in situ detoxification. Most importantly, ALSHC still had better adsorption performance (adsorption capacity of 30.95 mg g-1) than commercially activated carbon, even at pH = 9.00. The adsorption of Cr(VI) by ALSHC accorded with the pseudo-second-order kinetic model and Langmuir isotherm model, indicating a monolayer chemisorption process. The adsorption process was shown to be spontaneous and endothermic based on the thermodynamic characteristics (ΔG0 < 0, ΔH0 > 0, and ΔS0 > 0). The mechanism of Cr(VI) removal was mainly composed of three parts in sequence: Firstly, Cr(VI) in solution was quickly adsorbed onto ALSHC with protonated -NH2 through electrostatic attraction; subsequently, the adsorbed Cr(VI) on ALSHC was mostly detoxicated by in situ reduction; and finally, the reduced Cr(III) and the remaining Cr(VI) were fixed on the ALSHC surface by complexation. The prepared ALSHC displayed a certain superiority in Cr(VI) adsorption and had the prospect of further development.

The porous cantilever beam as a model for spinal implants: Experimental, analytical and finite element analysis of dynamic properties.

Investigation of the dynamic properties of implants is essential to ensure safety and compatibility with the host's natural spinal tissue. This paper presents a simplified model of a cantilever beam to investigate the effects of holes/pores on the structures. Free vibration test is one of the most effective methods to measure the dynamic response of a cantilever beam, such as natural frequency and damping ratio. In this study, the natural frequencies of cantilever beams made of polycarbonate (PC) containing various circular open holes were investigated numerically, analytically, and experimentally. The experimental data confirmed the accuracy of the natural frequencies of the cantilever beam with open holes calculated by finite element and analytical models. In addition, two finite element simulation methods, the dynamic explicit and modal dynamic methods, were applied to determine the damping ratios of cantilever beams with open holes. Finite element analysis accurately simulated the damped vibration behavior of cantilever beams with open holes when known material damping properties were applied. The damping behavior of cantilever beams with random pores was simulated, highlighting a completely different relationship between porosity, natural frequency and damping response. The latter highlights the potential of finite element methods to analyze the dynamic response of arbitrary and complex structures, towards improved implant design.

Hop2 Interacts with ATF4 to Promote Osteoblast Differentiation.

Activating transcription factor 4 (ATF4) is a member of the basic leucine zipper (bZip) transcription factor family required for the terminal differentiation of osteoblasts. Despite its critical importance as one of the three main osteoblast differentiation transcription factors, regulators of osteoblast terminal maturation remain poorly defined. Here we report the identification of homologous pairing protein 2 (Hop2) as a dimerization partner of ATF4 in osteoblasts via the yeast two-hybrid system. Deletional mapping revealed that the Zip domain of Hop2 is necessary and sufficient to bind ATF4 and to enhance ATF4-dependent transcription. Ectopic Hop2 expression in preosteoblasts increased endogenous ATF4 protein content and accelerated osteoblast differentiation. Mice lacking Hop2 (Hop2-/- ) have a normal stature but exhibit an osteopenic phenotype similar to the one observed in Atf4-/- mice, albeit milder, which is associated with decreased Osteocalcin mRNA expression and reduced type I collagen synthesis. Compound heterozygous mice (Atf4+/- :Hop2+/- ) display identical skeletal defects to those found in Hop2-/- mice. These results indicate that Hop2 plays a previous unknown role as a determinant of osteoblast maturation via its regulation of ATF4 transcriptional activity. Our work for the first time reveals a function of Hop2 beyond its role in guiding the alignment of homologous chromosomes. © 2019 American Society for Bone and Mineral Research.

Knockdown of Long Noncoding RNA LUCAT1 Inhibits Cell Viability and Invasion by Regulating miR-375 in Glioma.

Recently, long noncoding RNAs (lncRNAs) have emerged as new gene regulators and prognostic markers in several cancers, including glioma. Here we focused on lncRNA LUCAT1 on the progression of glioma. qRT-PCR was used to determine the expression of LUCAT1 and miR-375 in glioma tissues and cells. MTT and Transwell invasion assays were performed to determine the function of LUCAT1 in glioma progression. The bioinformatics tool DIANA was used to predict the targets of LUCAT1. Pearson's correlation analysis was performed to explore the correlation between LUCAT1 and miR-375. In the present study, we showed that LUCAT1 was substantially upregulated in glioma tissues and cells. LUCAT1 inhibition significantly suppressed the proliferation and invasion of glioma cells. Subsequently, DIANA showed that miR-375 was predicted to contain the complementary binding sites to LUCAT1. Luciferase reporter assay showed that miR-375 directly targeted LUCAT1. In addition, we found that miR-375 was downregulated in glioma tissues and negatively correlated with LUCAT1 expression in glioma tissues. Furthermore, the results showed that miR-375 could rescue the function of LUCAT1 in glioma progression. The lncRNA LUCAT1 was critical for the proliferation and invasion of glioma cells by regulating miR-375. Our findings indicated that LUCAT1 might offer a potential novel therapeutic target for the treatment of glioma.

Effect of triple junctions on deformation twinning in a nanostructured Cu-Zn alloy: A statistical study using transmission Kikuchi diffraction.

Scanning electron microscopy transmission Kikuchi diffraction is able to identify twins in nanocrystalline material, regardless of their crystallographic orientation. In this study, it was employed to characterize deformation twins in Cu/10 wt % Zn processed by high-pressure torsion. It was found that in 83% of grains containing twins, at least one twin intersects with a triple junction. This suggests that triple junctions could have promoted the nucleation of deformation twins. It should be cautioned that this technique might be unable to detect extremely small nanoscale twins thinner than its step size.

Expression of p16 and Survivin in gliomas and their correlation with cell proliferation.

The survival rate of glioma patients is very low, and a lack of effective diagnostic techniques are available at present. The current study aimed to investigate the expression of p16 and Survivin and their association with proliferation and apoptosis in gliomas, as well as patient characteristics and prognosis. In total, 62 glioma specimens were surgically resected and pathologically confirmed at the Zhumadian Central Hospital (Zhumadian, China) between June 2008 and February 2014. Clinical data, including the gender and age of the patients, as well as the location, infiltration degree, size and pathological stage of the glioma, was collected. In order to evaluate the expression of p16 and Survivin in the gliomas, the Ki-67 labeling index was used to evaluate cell proliferation activity. The number of argyrophilic nucleolar organizer regions and the rate of cellular apoptosis was examined using the terminal deoxynucleotidyl transferase dUTP nick end labeling method. The results were analyzed using SPSS 14.0 statistical software. The positive rate of p16 gene expression in the gliomas was 46.77% (29 cases), and p16 gene expression was positively correlated with the differentiation status, tumor size and pre-operative symptoms. The positive rate of Survivin expression in the gliomas was 69.88% (58 cases), and Survivin expression was positively correlated with tumor size, differentiation status and clinical stage. The proliferation activity of the gliomas was enhanced with increasing p16 and Survivin expression, while apoptosis was inhibited. In conclusion, the overexpression of p16 and Survivin was closely associated with uncontrolled cell proliferation and the inhibition of apoptosis in gliomas. The combined analysis of the expression of p16 and Survivin in gliomas may provide guidance with respect to the clinical diagnosis, evaluation, treatment and prognosis of patients with glioma.

Design and synthesis of cyclopropylamide analogues of combretastatin-A4 as novel microtubule-stabilizing agents.

A series of novel cyclopropylamide analogues of combretastatin-A4 (CA-4) were designed and synthesized. Most of them had significant in vitro antiproliferative activities, particularly for compounds 7i4, 7c4, 8a4, and 8c4. Moreover, compound 8c4 was also equally potent against paclitaxel resistant cancer cells. Interestingly, the novel cyclopropylamide analogues had different binding mechanisms from CA-4. Instead of inhibiting tubulin polymerization, these CA-4 derivatives were able to stimulate tubulin polymerization. Flow cytometry revealed that compound 8c4 arrested A549 cancer cells in the G2/M phase and resulted in cellular apoptosis. Further immunofluorescence assays revealed that compound 8c4 induced mitotic arrest in A549 cells through disrupting microtubule dynamics. In addition, compound 8c4 also effectively inhibited the tumor growth in the A549 xenograft model without causing significant loss of body weight. Compound 8c4 represents a novel class of microtubule-stabilizing agent and can be used as a promising lead for the development of new antitumor agents.

Transforming growth factor ß suppresses osteoblast differentiation via the vimentin activating transcription factor 4 (ATF4) axis.

ATF4 is an osteoblast-enriched transcription factor of the leucine zipper family. We recently identified that vimentin, a leucine zipper-containing intermediate filament protein, suppresses ATF4-dependent osteocalcin (Ocn) transcription and osteoblast differentiation. Here we show that TGFß inhibits ATF4-dependent activation of Ocn by up-regulation of vimentin expression. Osteoblasts lacking Atf4 (Atf4(-/-)) were less sensitive than wild-type (WT) cells to the inhibition by TGFß on alkaline phosphatase activity, Ocn transcription and mineralization. Importantly, the anabolic effect of a monoclonal antibody neutralizing active TGFß ligands on bone in WT mice was blunted in Atf4(-/-) mice. These data establish that ATF4 is required for TGFß-related suppression of Ocn transcription and osteoblast differentiation in vitro and in vivo. Interestingly, TGFß did not directly regulate the expression of ATF4; instead, it enhanced the expression of vimentin, a negative regulator of ATF4, at the post-transcriptional level. Accordingly, knockdown of endogenous vimentin in 2T3 osteoblasts abolished the inhibition of Ocn transcription by TGFß, confirming an indirect mechanism by which TGFß acts through vimentin to suppress ATF4-dependent Ocn activation. Furthermore, inhibition of PI3K/Akt/mTOR signaling, but not canonical Smad signaling, downstream of TGFß, blocked TGFß-induced synthesis of vimentin, and inhibited ATF4-dependent Ocn transcription in osteoblasts. Thus, our study identifies that TGFß stimulates vimentin production via PI3K-Akt-mTOR signaling, which leads to suppression of ATF4-dependent Ocn transcription and osteoblast differentiation.

Chondrocytic Atf4 regulates osteoblast differentiation and function via Ihh.

Atf4 is a leucine zipper-containing transcription factor that activates osteocalcin (Ocn) in osteoblasts and indian hedgehog (Ihh) in chondrocytes. The relative contribution of Atf4 in chondrocytes and osteoblasts to the regulation of skeletal development and bone formation is poorly understood. Investigations of the Atf4(-/-);Col2a1-Atf4 mouse model, in which Atf4 is selectively overexpressed in chondrocytes in an Atf4-null background, demonstrate that chondrocyte-derived Atf4 regulates osteogenesis during development and bone remodeling postnatally. Atf4 overexpression in chondrocytes of the Atf4(-/-);Col2a1-Atf4 double mutants corrects the reduction in stature and limb in Atf4(-/-) embryos and rectifies the decrease in Ihh expression, Hh signaling, proliferation and accelerated hypertrophy that characterize the Atf4(-/-) developing growth plate cartilages. Unexpectedly, this genetic manipulation also restores the expression of osteoblastic marker genes, namely Ocn and bone sialoprotein, in Atf4(-/-) developing bones. In Atf4(-/-);Col2a1-Atf4 adult mice, all the defective bone parameters found in Atf4(-/-) mice, including bone volume, trabecular number and thickness, and bone formation rate, are rescued. In addition, the conditioned media of ex vivo cultures from wild-type or Atf4(-/-);Col2a1-Atf4, but not Atf4(-/-) cartilage, corrects the differentiation defects of Atf4(-/-) bone marrow stromal cells and Ihh-blocking antibody eliminates this effect. Together, these data indicate that Atf4 in chondrocytes is required for normal Ihh expression and for its paracrine effect on osteoblast differentiation. Therefore, the cell-autonomous role of Atf4 in chondrocytes dominates the role of Atf4 in osteoblasts during development for the control of early osteogenesis and skeletal growth.

Atf4 regulates chondrocyte proliferation and differentiation during endochondral ossification by activating Ihh transcription.

Activating transcription factor 4 (Atf4) is a leucine-zipper-containing protein of the cAMP response element-binding protein (CREB) family. Ablation of Atf4 (Atf4(-/-)) in mice leads to severe skeletal defects, including delayed ossification and low bone mass, short stature and short limbs. Atf4 is expressed in proliferative and prehypertrophic growth plate chondrocytes, suggesting an autonomous function of Atf4 in chondrocytes during endochondral ossification. In Atf4(-/-) growth plate, the typical columnar structure of proliferative chondrocytes is disturbed. The proliferative zone is shortened, whereas the hypertrophic zone is transiently expanded. The expression of Indian hedgehog (Ihh) is markedly decreased, whereas the expression of other chondrocyte marker genes, such as type II collagen (Col2a1), PTH/PTHrP receptor (Pth1r) and type X collagen (Col10a1), is normal. Furthermore, forced expression of Atf4 in chondrocytes induces endogenous Ihh mRNA, and Atf4 directly binds to the Ihh promoter and activates its transcription. Supporting these findings, reactivation of Hh signaling pharmacologically in mouse limb explants corrects the Atf4(-/-) chondrocyte proliferation and short limb phenotypes. This study thus identifies Atf4 as a novel transcriptional activator of Ihh in chondrocytes that paces longitudinal bone growth by controlling growth plate chondrocyte proliferation and differentiation.

Vimentin inhibits ATF4-mediated osteocalcin transcription and osteoblast differentiation.

Activating transcription factor 4 (ATF4) is an osteoblast-enriched transcription factor that regulates osteocalcin transcription and osteoblast terminal differentiation. To identify functional partners of ATF4, we applied ROS17/2.8 osteoblast nuclear extracts and purified recombinant His-ATF4 onto a Ni(+) affinity matrix chromatography column. Vimentin was identified by liquid chromatography-mass spectrometry. Coimmunoprecipitation and pulldown assays revealed that vimentin interacted with ATF4 with its first leucine zipper domain. DNA cotransfection and gel retardation demonstrated that vimentin inhibited the transactivation activity of ATF4 on osteocalcin by preventing it to bind OSE1, the ATF4 binding site on the osteocalcin promoter. Northern hybridization revealed that vimentin was expressed at a high level in immature osteoblasts and a low level in fully differentiated osteoblasts. Down-regulation of vimentin by small interfering RNA induced endogenous osteocalcin transcription in immature osteoblasts. Conversely, ectopic overexpression of vimentin in osteoblasts inhibited osteoblast differentiation as shown by lower alkaline phosphatase activity, delayed mineralization, and decreased expression of osteoblast marker genes such as bone sialoprotein and osteocalcin. Together, our data uncover a novel mechanism whereby a cytoskeletal protein, vimentin, acts as a break on differentiation in immature osteoblasts by interacting with ATF4.

No genetic association between polymorphisms in the kainate-type glutamate receptor gene, GRIK4, and schizophrenia in the Chinese population.

BACKGROUND: Schizophrenia is a chronic psychiatric disorder with a strong genetic component. Several studies have suggested that dysfunctions in the glutamatergic transmission are linked to the pathogenesis of schizophrenia, and that the kainate ionotropic glutamate receptors are involved in this mechanism. A recent study provides cytogenetic and genetic evidence to support a role for the kainate-type glutamate receptor gene (GRIK4), in schizophrenia. A systematic case-control association study of GRIK4 involving a Scottish population found that three SNPs, rs4935752, rs6589846 and rs4430518, were associated with schizophrenia. METHODS: Here, we investigated rs4935752, rs6589846, rs4430518 and other 2 SNPs within the GRIK4 gene in an association study of the Chinese population. Our sample consisted of 288 schizophrenia and 288 control subjects. All recruits were Han Chinese drawn from the city of Shanghai. RESULTS: No individual SNP nor any haplotype was associated with schizophrenia in our study. CONCLUSION: These results suggest that the five SNPs within the GRIK4 gene are unlikely to play a major role in the susceptibility to schizophrenia in the Chinese population.

ATF4 is a substrate of RSK2 and an essential regulator of osteoblast biology; implication for Coffin-Lowry Syndrome.

Coffin-Lowry Syndrome (CLS) is an X-linked mental retardation condition associated with skeletal abnormalities. The gene mutated in CLS, RSK2, encodes a growth factor-regulated kinase. However, the cellular and molecular bases of the skeletal abnormalities associated with CLS remain unknown. Here, we show that RSK2 is required for osteoblast differentiation and function. We identify the transcription factor ATF4 as a critical substrate of RSK2 that is required for the timely onset of osteoblast differentiation, for terminal differentiation of osteoblasts, and for osteoblast-specific gene expression. Additionally, RSK2 and ATF4 posttranscriptionally regulate the synthesis of Type I collagen, the main constituent of the bone matrix. Accordingly, Atf4-deficiency results in delayed bone formation during embryonic development and low bone mass throughout postnatal life. These findings identify ATF4 as a critical regulator of osteoblast differentiation and function, and indicate that lack of ATF4 phosphorylation by RSK2 may contribute to the skeletal phenotype of CLS.