Halogen Substitution Regulates High Temperature Dielectric Switch in Lead-Free Chiral Hybrid Perovskites.

Hybrid metal halides (HMHs) based phase transition materials have received widespread attention due to their excellent performance and potential applications in energy harvesting, optoelectronics, ferroics, and actuators. Nevertheless, effectively regulating the properties of phase transitions is still a thorny problem. In this work, two chiral lead-free HMHs (R-3FP)2 SbCl5 (1; 3FP=3-fluoropyrrolidinium) and (R-3FP)2 SbBr5 (2) were synthesized. By replacing the halide ions in the inorganic skeleton, the phase transition temperature of 2 changes with an increase of about 20 K, compared with 1. Meanwhile, both compounds display reversible dielectric switching properties. Through crystal structure analysis and Hirshfeld surface analysis, their phase transitions are ascribed to the disorder of the cations and deformation of the inorganic chains.

Curcumin inhibits the invasion and migration of pancreatic cancer cells by upregulating TFPI-2 to regulate ERK- and JNK-mediated epithelial-mesenchymal transition.

PURPOSE: Pancreatic cancer (PC) is one of the most deadly human malignancies. Curcumin is a natural polyphenolic compound with wide-ranging pharmacological effects. Growing evidence suggests that curcumin has anticancer activity against PC, but the mechanism remains incompletely elucidated. This study aimed to investigate the effects and mechanisms of curcumin on the invasion and migration of PC cells. METHODS: Effect of curcumin on tissue factor pathway inhibitor (TFPI)-2 mRNA expression in PC cells was initially identified using qRT-PCR. Cytotoxicity of curcumin was assessed with MTT assays and IC50 was calculated. Involvement of ERK and JNK pathways, as well as protein expression of TFPI-2 and epithelial-mesenchymal transition (EMT)-related markers, were detected using immunoblotting. Invasion and migration of PC cells were examined using Transwell assays. TFPI-2 expression was manipulated by transfection with siRNA and shRNA. Rescue assays were used to validate the effect of curcumin on cell invasion and migration via TFPI-2. RESULTS: Curcumin increased the expression of TFPI-2 mRNA and protein in PC cells and attenuated cell invasion and migration. Curcumin also inhibited ERK and JNK pathways and EMT in PC cells. Knockdown of TFPI-2 partially reversed the inhibition of ERK and JNK pathways and EMT by curcumin. Mechanistically, curcumin upregulated TFPI-2, thereby inhibiting the ERK and JNK pathways, leading to the inhibition of EMT in PC cells. CONCLUSION: Collectively, curcumin inhibits ERK- and JNK-mediated EMT through upregulating TFPI-2, which in turn suppresses the migration and invasion of PC cells. These findings provide new insights into the antitumor mechanism of curcumin.

A Two-Dimensional Hybrid Lead Bromide Ferroelectric Semiconductor with an Out-of-Plane Polarization.

A two-dimensional (2D) organic-inorganic hybrid perovskite (OIHP) material with out-of-plane ferroelectricity is the key to the miniaturization of vertical-sandwich-type ferroelectric optoelectronic devices. However, 2D OIHP ferroelectrics with out-of-plane polarization are still scarce, and effective design strategies are lacking. Herein, we report a novel 2D Dion-Jacobson perovskite ferroelectric semiconductor synthesized by a rigid-to-flexible cationic tailoring strategy, achieving an out-of-plane polarization of 1.7 µC/cm2 and high photoresponse. Integrating out-of-plane ferroelectricity with excellent photoelectric properties affords a promising platform to investigate ferroelectricity-related effects in vertical optoelectronic devices.

Overexpressed HSPA2 correlates with tumor angiogenesis and unfavorable prognosis in pancreatic carcinoma.

Heat shock-related 70-kDa protein 2 (HSPA2) is known to correlate with tumor development and progression. This work aimed to determine the expression and prognostic roles of HSPA2 in pancreatic carcinoma. Tumor and their corresponding non-tumor tissues were obtained from 80 patients with pancreatic carcinoma. HSPA2 expression in tumor and non-tumor tissues was evaluated by immunohistochemistry. Expression of vascular endothelial growth factor (VEGF) and CD31 in tumor tissues were also evaluated by immunostaining. The relationships of HSPA2 with clinicopathological data, tumor angiogenesis and prognosis were analyzed. The results showed that HSPA2 expression was significantly elevated in tumor tissues compared with adjacent non-tumor tissues (P < 0.05). High HSPA2 expression was significantly associated with aggressive clinicopathological characteristics. HSPA2 staining was positively correlated with VEGF (r = 0.466, P < 0.001) and microvessel density (MVD) (r = 0.366, P = 0.001) in tumor tissues. Patients with high HSPA2 expression showed worse relapse-free survival (RFS) (P < 0.001) and overall survival (OS) (P < 0.001) than those with low HSPA2 expression. Multivariate analysis indicated that high HSPA2 expression was an independent predictor for poor RFS (P < 0.001) and OS (P = 0.001). Taken together, overexpressed HSPA2 is correlated with tumor angiogenesis and poor prognosis in pancreatic carcinoma. HSPA2 may play an important role in tumor progression, and serve as a potential biomarker for the prediction of adverse prognosis in pancreatic carcinoma.

Inhibiting Hexamer Disassembly of Human UDP-Glucose Dehydrogenase by Photoactivated Amino Acid Cross-Linking.

The enzyme UDP-glucose dehydrogenase (UGDH) catalyzes the reaction of UDP-glucose to UDP-glucuronate through two successive NAD(+)-dependent oxidation steps. Human UGDH apoprotein is purified as a mixture of dimeric and hexameric species. Addition of substrate and cofactor stabilizes the oligomeric state to primarily the hexameric form. To determine if the dynamic conformations of hUGDH are required for catalytic activity, we used site-specific unnatural amino acid incorporation to facilitate cross-linking of monomeric subunits into predominantly obligate oligomeric species. Optimal cross-linking was achieved by encoding p-benzoyl-l-phenylalanine at position 458, normally a glutamine located within the dimer-dimer interface, and exposing the enzyme to long wavelength ultraviolet (UV) radiation in the presence of substrate and cofactor. Hexameric complexes were purified by gel filtration chromatography and found to contain significant fractions of dimer and trimer (approximately 50%) along with another 10% higher-molecular mass species. The activity of the cross-linked enzyme was reduced by almost 60% relative to that of the un-cross-linked UGDH mutant, and UV exposure had no effect on the activity of the wild-type enzyme. These results support a model for catalysis in which the ability to dissociate the dimer-dimer interface is as important for maximal enzyme function as has been previously shown for the formation of the hexamer.

Sulfotyrosine dipeptide: Synthesis and evaluation as HIV-entry inhibitor.

Human immunodeficiency virus type 1 (HIV-1) is responsible for the worldwide AIDS pandemic. Due to the lack of prophylactic HIV-1 vaccine, drug treatment of the infected patients becomes essential to reduce the viral load and to slow down progression of the disease. Because of drug resistance, finding new antiviral agents is necessary for AIDS drug therapies. The interaction of gp120 and co-receptor (CCR5/CXCR4) mediates the entry of HIV-1 into host cells, which has been increasingly exploited in recent years as the target for new antiviral agents. A conserved co-receptor binding site on gp120 that recognizes sulfotyrosine (sTyr) residues represents a structural target to design novel HIV entry inhibitors. In this work, we developed an efficient synthesis of sulfotyrosine dipeptide and evaluated it as an HIV-1 entry inhibitor.

Anticancer activity of Honokiol against lymphoid malignant cells via activation of ROS-JNK and attenuation of Nrf2 and NF-κB.

PURPOSE: To evaluate the effect of Honokiol (HK) in the ROS-JNK pro-apoptotic pathway and NF-κB, Nrf2 anti-apoptotic pathways, in order to seek a possible explanation for its anticancer efficacy. METHODS: The Raji and Molt4 cell lines were utilized for the determination of anticancer activity against lymphoid malignant cells. BALB/C nude mice, weighing 18-20g each and aged 4-5 weeks, were procured from the central animal house facility. For establishing non-Hodgkin lymphoma in BALB/C, the nude mice were subcutaneously administered 1×10(7) Raji cells, suspended in 0.2 mL sterile PBS on the back. The mice were then randomly divided into 3 groups (6 mice in each group). HK cytotoxicity was determined using the colorimetric MTT assay. RESULTS: In colorimetry-based MTT assay, the cytotoxicity of HK was determined at different time intervals, in lymphoid malignant Raji and Molt4 cell lines. HK exhibited prominent cytotoxicity against Raji cell lines with IC50 of 0.092 ± 0.021 µM. In Molt4 cells, the administration of HK caused significant cytotoxicity with IC50 of 0.521 ± 0.115 µM. The treatment of HK caused significant increase in the activity of reactive oxygen species (ROS) in Raji cells at various time intervals. Moreover, the level of NF-κB was significantly reduced in the presence of HK, which could be easily understood by a decreased level of p-65. Furthermore, in the presence of ROS inhibitor NAC (10mM) for 24 hrs, the JNK pathway was markedly activated, together with inhibition of NF-κB activity and a reduced level of Nrf2 expression. To further confirm the in vitro results by in vivo activity, HK was observed to inhibit the proliferation of Raji cells in vivo, which might be attributable to its inhibitory effect against the progression of the tumor (p<0.05). CONCLUSION: The present study suggests that HK causes considerable induction of apoptosis in lymphoid malignant cells, both in vitro and in vivo, whereas the generation of ROS might serve as an underlying mechanism for inducing apoptosis.

Factors related to the time to cryptorchidism surgery--a nationwide, population-based study in Taiwan.

BACKGROUND/PURPOSE: Current guidelines recommend that the optimal timing for cryptorchidism surgery is by the age of 12 months. This study investigated the trend of surgical timing and examined the factors associated with time to surgery for cryptorchidism in Taiwan by using a nationwide, population-based database. METHODS: The present study utilized the Longitudinal Health Insurance Database 2005, a subset of the National Health Insurance Research Database, which contains data on all paid medical benefit claims over the period 1997-2007 for a subset of 1 million beneficiaries randomly drawn from 22.72 million individuals enrolled in the National Health Insurance program in 2005. We analyzed the timing of surgery in boys younger than 18 years with diagnosis of cryptorchidism. RESULTS: We identified 547 boys who underwent surgery under 18 years of age. Approximately 79.2% of study participants received surgery after the age of 12 months. A multivariate analysis showed that several factors were significantly associated with time to surgery: age of the physician making the diagnosis, age of the surgeon performing the surgery, age of the patient at the first diagnosis of cryptorchidism, and number of previous clinic visits with the diagnosis of cryptorchidism and urbanization level of the patient's residence. CONCLUSION: A surprisingly high rate (79.2%) of all study participants underwent surgery beyond the optimal timing. Certain doctor and patient factors were associated with time to cryptorchidism surgery. Improving the alertness and education of parents and specialists may lead to earlier surgeries.

Chiral three-dimensional organic-inorganic lead iodide hybrid semiconductors.

Chiral hybrid metal halides (CHMHs) have received a considerable amount of attention in chiroptoelectronics, spintronics, and ferroelectrics due to their superior optoelectrical properties and structural flexibility. Owing to limitations in synthesis, the theoretical prediction of room-temperature stable chiral three-dimensional (3D) CHFClNH3PbI3 has not been successfully prepared, and the optoelectronic properties of such structures cannot be studied. Herein, we have successfully constructed two pairs of chiral 3D lead iodide hybrids (R/S/Rac-3AEP)Pb2I6 (3R/S/Rac, 3AEP = 3-(1-aminoethyl)pyridin-1-ium) and (R/S/Rac-2AEP)Pb2I6 (2R/S/Rac, 2AEP = 2-(1-aminoethyl)pyridin-1-ium) through chiral introduction and ortho substitution strategies, and obtained bulk single crystals of 3R/S/Rac. The 3R/S exhibits optical activity and bulk photovoltaic effect induced by chirality. The 3R crystal device exhibits stable circularly polarized light performance at 565 nm with a maximum anisotropy factor of 0.07, responsivity of 0.25 A W-1, and detectivity of 3.4 × 1012 jones. This study provides new insights into the synthesis of chiral 3D lead halide hybrids and the development of chiral electronic devices.

Tuning ferroelectric phase transition temperature by enantiomer fraction.

Tuning phase transition temperature is one of the central issues in phase transition materials. Herein, we report a case study of using enantiomer fraction engineering as a promising strategy to tune the Curie temperature (TC) and related properties of ferroelectrics. A series of metal-halide perovskite ferroelectrics (S-3AMP)x(R-3AMP)1-xPbBr4 was synthesized where 3AMP is the 3-(aminomethyl)piperidine divalent cation and enantiomer fraction x varies between 0 and 1 (0 and 1 = enantiomers; 0.5 = racemate). With the change of the enantiomer fraction, the TC, second-harmonic generation intensity, degree of circular polarization of photoluminescence, and photoluminescence intensity of the materials have been tuned. Particularly, when x = 0.70 - 1, a continuously linear tuning of the TC is achieved, showing a tunable temperature range of about 73 K. This strategy provides an effective means and insights for regulating the phase transition temperature and chiroptical properties of functional materials.

Chemically Asymmetric Polymers Manipulate the Crystallization of Two-Dimensional Covalent Organic Frameworks to Synthesize Processable Nanosheets.

Nanosheets derived from two-dimensional covalent organic frameworks (2D COFs) are increasingly desirable in various fields. While breakthroughs in the chemical and physical delamination of 2D COFs are rising, precisely regulating the growth of the COF nanosheets has not been realized yet. Herein, we report an effective strategy of polymer-manipulated crystallization to accurately control the growth of COF nanosheets. Chemically asymmetric polyvinylpyrrolidone (PVP) is developed as the manipulator that selectively interacts with the aldehydes and (100) facet to induce anisotropic growth of COFs. The number of PVP constitutional units determines this specific interaction, leading to molecularly thin but thickness-controllable nanosheets with excellent dispersity. We process these nanosheets into robust A4-sized membranes for ultraselective molecular separation. The membrane intercalated with long-chain PVP demonstrates largely improved performance, surpassing the reported COF membranes. This work reports a strategy for anisotropically crystallizing 2D COFs to yield processable nanosheets toward practical applications.

Tumorigenic and immunological roles of Heat shock protein A2 in pancreatic cancer: a bioinformatics analysis.

OBJECTIVE: Heat shock protein A2 has been reported to be tightly associated with tumorigenesis and tumor progression. This study aimed to determine the oncogenic and immunological roles of Heat shock protein A2 in pancreatic cancer by bioinformatics. METHODS: Expression of Heat shock protein A2 in tumorous and normal specimens of pancreatic cancer was analyzed using the Cancer Genome Atlas and the Cancer Genome Atlas + Genotype-Tissue Expression data sets, respectively. Relationships of Heat shock protein A2 expression with immune infiltrates in pancreatic cancer were assessed. Heat shock protein A2-associated coexpressed genes in pancreatic cancer were obtained, followed by the implementation of enrichment analysis. RESULTS: The data demonstrated that Heat shock protein A2 was significantly overexpressed in tumorous samples compared with normal samples. Heat shock protein A2 expression was remarkably positively interrelated with CD8+ T cell, neutrophil, dendritic cell, and macrophage, but not with CD4+ T and B cells. Heat shock protein A2 expression was markedly positively relevant to both cancer-associated fibroblast and endothelial cell. Enrichment data revealed that Heat shock protein A2 was intimately involved in the tumorigenesis and progression of pancreatic cancer. CONCLUSION: Heat shock protein A2 is upregulated in pancreatic cancer and is closely associated with tumor immunity and aggressive progression.

Upregulated HSPA2 predicts early relapse of pancreatic cancer after surgery.

BACKGROUND: Heat shock protein A2 (HSPA2) is known to relate to the pathogenesis and progress of cancer. This study aimed to investigate the connection between HSPA2 and early postsurgical relapse of pancreatic cancer (PC). METHODS: Expression of HSPA2 in 85 pairs of cancerous and matched noncancerous samples was determined by immunostaining method. The relationship between HSPA2 expression and early postsurgical recurrence was assessed using logistic regression. The performance and potential application of HSPA2 expression to predict early postsurgical recurrence was evaluated by receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA). RESULTS: HSPA2 expression in tumor specimens was markedly elevated compared with non-tumor specimens. Logistic regression analysis indicated that HSPA2 upregulation was an independent risk marker for early postsurgical recurrence of PC. ROC curve analysis and DCA demonstrated that both the area under the curve (AUC) and the net benefit of HSPA2 expression were higher than those of other clinicopathologic features in predicting early postsurgical relapse of PC. The combination of HSPA2 expression with other malignant clinicopathologic characteristics had greater AUC and net benefit relative to them alone in predicting early postsurgical recurrence. CONCLUSIONS: Upregulated HSPA2 independently predicts early postsurgical recurrence of PC and has superior predictive performance and potential application value when combined with malignant clinicopathologic features. Our findings reveal that HSPA2 is a promising predictor for early postoperative relapse of PC.

Pathological changes in multiple organs of rats with severe acute pancreatitis treated by baicalin and octreotide.

BACKGROUND: Severe acute pancreatitis (SAP) features fatal pathogenetic conditions and high mortality rate. The study of SAP complicated with multiple organ injuries is of important significance. In this study, we explored the protective effect of baicalin on multiple organs of SAP rats and compared it with that of octreotide through light and electron microscopic observations of the pathological changes. METHODS: The improved Aho method was used to prepare SAP rat models. These rats were then randomly divided into a sham-operated group (n=45), a model control group (n=45), baicalin-treated group (n=45) and octreotide-treated group (n=45). Based on the difference in time points after operation, these groups were subdivided into 3, 6 and 12 hour subgroups (n=15). At the corresponding time point after operation, the mortality rate of rats was recorded, and then the rats were humanely killed to take samples of multiple organs that were subsequently examined for pathological changes under light and electron microscopy. RESULTS: At 12 hours after operation, the mortality rate of rats in the baicalin- and octreotide-treated groups was lower than that in the model control group (P<0.05). Compared to the model control group, the pathological changes and pathological scores in the baicalin- and octreotide-treated groups were mitigated and relieved to varying degrees. The pathological changes under electron microscopy were also improved. CONCLUSIONS: Both baicalin and octreotide show good protective effects on multiple organs of SAP rats. Baicalin as a new drug has good prospects in the treatment of SAP.

Study on protecting effects of baicalin and octreotide on hepatic injury in rats with severe acute pancreatitis.

AIM: To investigate the protective effects and mechanisms of baicalin and octreotide on hepatic injury in rats with severe acute pancreatitis (SAP). METHODS: The SAP rat models were prepared and randomly assigned to the model control group, baicalin treated group, and octreotide treated group while other healthy rats were assigned to the sham-operated group. Rat mortality, levels of ALT, AST, liver and pancreas pathological changes in all groups were observed at 3, 6 and 12 h after operation. Tissue microarray (TMA) sections of hepatic tissue were prepared to observe expression levels of Bax, Bcl-2 protein and caspase-3, and changes of apoptotic indexes. RESULTS: Rat survival at 12 h, expression levels of Bax, caspase-3 protein and apoptotic indexes of liver were all significantly higher in treated groups than in model control group. While the liver and pancreas pathological scores, contents of ALT, AST, and expression levels of Bcl-2 protein were all lower in treated groups than in the model control group. CONCLUSION: Both baicalin and octreotide can protect rats with SAP by decreasing the contents of ALT, AST and expression levels of Bcl-2 protein, and improving the expression levels of Bax protein, caspase-3 protein, and inducing apoptosis.

Influence of dexamethasone on mesenteric lymph node of rats with severe acute pancreatitis.

AIM: To study the influence and mechanisms of dexamethasone on mesenteric lymph node of rats with severe acute pancreatitis (SAP). METHODS: The SAP rats were assigned to model, treated or sham-operated groups. The mortality, pathological changes of mesenteric lymph nodes, expression levels of NF-kappa B, P-selectin, Bax, Bcl-2 and caspase-3 protein and changes in apoptotic indexes in lymph nodes were observed at 3, 6 and 12 h after operation. The blood levels of endotoxin, superoxide dismutase (SOD), malondialdehyde (MDA), and endothelin-1 (ET-1) in blood were determined. RESULTS: SOD content, expression of Bax protein and apoptotic index were significantly higher in the treated group than in the model group at different time points (P < 0.05 or P < 0.01). Other blood-detecting indexes and histopathological scores of mesenteric lymph nodes were lower in the treated than in the model group (P < 0.05, P < 0.01 or P < 0.01). NF-kappa B protein expression was negative in all groups. Comparing P-selectin and caspase-3 expression levels among all three groups, there was no marked difference between the model and treated group. CONCLUSION: Dexamethasone can protect mesenteric lymph nodes. The mechanism may be by reducing the content of inflammatory mediators in the blood and inducing lymphocyte apoptosis.

Tumorigenic and immunological roles of Heat shock protein A2 in pancreatic cancer: a bioinformatics analysis

SUMMARY OBJECTIVE: Heat shock protein A2 has been reported to be tightly associated with tumorigenesis and tumor progression. This study aimed to determine the oncogenic and immunological roles of Heat shock protein A2 in pancreatic cancer by bioinformatics. METHODS: Expression of Heat shock protein A2 in tumorous and normal specimens of pancreatic cancer was analyzed using the Cancer Genome Atlas and the Cancer Genome Atlas + Genotype-Tissue Expression data sets, respectively. Relationships of Heat shock protein A2 expression with immune infiltrates in pancreatic cancer were assessed. Heat shock protein A2-associated coexpressed genes in pancreatic cancer were obtained, followed by the implementation of enrichment analysis. RESULTS: The data demonstrated that Heat shock protein A2 was significantly overexpressed in tumorous samples compared with normal samples. Heat shock protein A2 expression was remarkably positively interrelated with CD8+ T cell, neutrophil, dendritic cell, and macrophage, but not with CD4+ T and B cells. Heat shock protein A2 expression was markedly positively relevant to both cancer-associated fibroblast and endothelial cell. Enrichment data revealed that Heat shock protein A2 was intimately involved in the tumorigenesis and progression of pancreatic cancer. CONCLUSION: Heat shock protein A2 is upregulated in pancreatic cancer and is closely associated with tumor immunity and aggressive progression.

Evolution of Src Homology 2 (SH2) Domain to Recognize Sulfotyrosine.

Protein tyrosine O-sulfation is considered as the most common type of post-translational tyrosine modification in nature and plays important roles in extracellular biomolecular interactions. To facilitate the mapping, biological study, and medicinal application of this type of post-translational modification, we seek to evolve a small protein scaffold that recognizes sulfotyrosine with high affinity. We focused our efforts on the engineering of the Src Homology 2 (SH2) domain, which represents the largest class of known phosphotyrosine-recognition domain in nature and has a highly evolvable binding pocket. By using phage display, we successfully engineered the SH2 domain to recognize sulfotyrosine with high affinity. The best mutant, SH2-60.1, displayed more than 1700 fold higher sulfotyrosine-binding affinity than that of the wild-type SH2 domain. We also demonstrated that the evolved SH2 domain mutants could be used to detect sulfoprotein levels on the cell surface. These evolved SH2 domain mutants can be potentially applied to the study of protein tyrosine O-sulfation with proper experimental designs.

Fine-tuning interaction between aminoacyl-tRNA synthetase and tRNA for efficient synthesis of proteins containing unnatural amino acids.

By using a directed evolution approach, we have identified aminoacyl-tRNA synthetase variants with significantly enhanced activity for the incorporation of unnatural amino acids into proteins in response to the amber nonsense codon in bacteria. We demonstrated that the optimization of anticodon recognition of tRNA by aminoacyl-tRNA synthetase led to improved incorporation efficiency that is unnatural amino acid-specific. The findings will facilitate the creation of an optimized system for the genetic incorporation of unnatural amino acids in bacteria.