Work Function Prediction by Graph Neural Networks for Configurationally Hybridized Boron-Doped Graphene.

Graphene, serving as electrodes, is widely applied in electronic and optoelectronic devices. Work function as one of the fundamental intrinsic characteristics of graphene directly affects the interfacial properties of the electrodes, thereby affecting the performance of the devices. Much work has been done to regulate the work function of graphene to expand its application fields, and doping has been demonstrated as an effective method. However, the numerous types of doped graphene make the investigation of its work function time-consuming and labor-intensive. In order to quickly obtain the relationship between the structure and property, a deep learning method is employed to predict the work function in this study. Specifically, a data set of over 30,000 compositions with the work function on boron-doped graphene at different concentrations and doping positions via density functional theory simulations was established through ab initio calculations. Then, a novel fusion model (GT-Net) combining transformers and graph neural networks (GNNs) was proposed. After that, improved effective GNN-based descriptors were developed. Finally, three different GNN methods were compared, and the results show that the proposed method could accurately predicate the work function with the R2 = 0.975 and RMSE = 0.027. This study not only provides the possibility of designing materials with specific properties at the atomic level but also demonstrates the performance of GNNs on graph-level tasks with the same graph structure and atomic number.

Hemin with Peroxidase Activity Can Inhibit the Oxidative Damage Induced by Ultraviolet A.

Excessive reactive oxygen species (ROS), a highly reactive substance that contains oxygen, induced by ultraviolet A (UVA) cause oxidative damage to skin. We confirmed that hemin can catalyze the reaction of tyrosine (Tyr) and hydrogen peroxide (H2O2). Catalysis was found to effectively reduce or eliminate oxidative damage to cells induced by H2O2 or UVA. The scavenging effects of hemin for other free-radical ROS were also evaluated through pyrogallol autoxidation, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·)-scavenging assays, and phenanthroline-Fe2+ assays. The results show that a mixture of hemin and tyrosine exhibits strong scavenging activities for H2O2, superoxide anion (O2-·), DPPH·, and the hydroxyl radical (·OH). Furthermore, the inhibition of oxidative damage to human skin keratinocyte (HaCaT) cells induced by H2O2 or UVA was evaluated. The results show that catalysis can significantly reduce the ratio of cell apoptosis and death and inhibit the release of lactate dehydrogenase (LDH), as well as accumulation of malondialdehyde (MDA). Furthermore, the resistance to apoptosis was found to be enhanced. These results show that the mixture of hemin and tyrosine has a significantly protective effect against oxidative damage to HaCaT cells caused by UVA, suggesting it as a protective agent for combating UVA damage.

High Expression Level of α2-3-Linked Sialic Acids on Salivary Glycoproteins of Breastfeeding Women May Help to Protect Them from Avian Influenza Virus Infection.

Terminal sialic acids (Sia) on soluble glycoprotein of saliva play an important role in the clearance of influenza virus. The aim of this study is to investigate the alteration of sialylation on the salivary proteins of women during the lactation period and its effect on the saliva binding ability to virus. In total, 210 saliva samples from postpartum women with and without breastfeeding were collected, and the expression level of α2-3/6-linked Sia on the whole salivary proteins and specific glycoproteins of IgA and MUC5B from different groups were tested and verified using lectin microarray, blotting analysis and ELISA based method. The H1N1 vaccine and three strains of Avian influenza virus (AIV) were used for the saliva binding assay. Results showed that the variation in salivary expression level of α2-3-linked Sia was much more obvious than the α2-6-linked Sia, which was up-regulated significantly in the breastfeeding groups compared to the non-breastfeeding groups at the same postpartum stage. Furthermore, the binding abilities of salivary glycoproteins to AIV strains and H1N1 vaccine were increased in breastfeeding groups accordingly. This finding adds new evidence for the maternal benefit of breastfeeding and provides new thinking to protect postpartum women from AIV infection.

Peptide-based Self-assembly: Design, Bioactive Properties, and Its Applications.

The self-assembly of peptides is very popular in biomedical fields. Peptide-based assemblies have been used as an ideal candidate for drug/gene delivery, tissue engineering, and antibacterial/anticancer agents. The morphology and structure of peptide self-assembly can be changed by altering the molecular structure and the self-assembly conditions. Engineering peptide assemblies present great potential in medical fields. In this review, the structure and function of peptide self-assembly have been described. Also, the advances in peptide- based self-assembly have been highlighted in biomedical applications, such as drug packaging and delivery, tissue engineering, antibacterial agents, siRNA-targeted delivery and vaccines. Moreover, the challenges and future perspectives of the self-assembly of polypeptides are discussed.

Extracting Multi-Scale and Salient Features by MSE Based U-Structure and CBAM for Sleep Staging.

According to the World Health Organization, more and more people in the world are suffering from somnipathy. Automatic sleep staging is critical for assessing sleep quality and assisting in the diagnosis of psychiatric and neurological disorders caused by somnipathy. Many researchers employ deep learning methods for sleep stage classification and have achieved high performance. However, there are still no effective methods to modeling intrinsic characteristics of salient wave in different sleep stages from physiological signals. And transition rules hidden in signals from one to another sleep stage cannot be identified and captured. In addition, class imbalance problem in dataset is not conducive to building a robust classification model. To solve these problems, we construct a deep neural network combining MSE(Multi-Scale Extraction) based U-structure and CBAM (Convolutional Block Attention Module) to extract the multi-scale salient waves from single-channel EEG signals. The U-structured convolutional network with MSE is utilized to extract multi-scale features from raw EEG signals. After that, the CBAM is used to focus more on salient variation and then learn transition rules between successive sleep stages. Further, a class adaptive weight cross entropy loss function is proposed to solve the class imbalance problem. Experiments in three public datasets show that our model greatly outperform the state-of-the-art results compared with existing methods. The overall accuracy and macro F1-score (Sleep-EDF-39: 90.3%-86.2, Sleep-EDF-153: 89.7%-85.2, SHHS: 86.8%-83.5) on three public datasets suggest that the proposed model is very promising to completely take place of human experts for sleep staging.

DenSleepNet: DenseNet based model for sleep staging with two-frequency feature fusion and coordinate attention.

Sleep staging is often applied to assess the quality of sleep and also be used to prevent and monitor psychiatric disorders caused by sleep. However, it remains a challenge to extract the discriminative features of salient waveforms in sleep EEG and enable the network to effectively classify sleep stages by emphasizing these crucial features, thus achieving higher accuracy. In this study, an end-to-end deep learning model based on DenseNet for automatic sleep staging is designed and constructed. In the framework, two convolutional branches are devised to extract the underlying features (Two-Frequency Feature) at various frequencies, which are then fused and input into the DenseNet module to extract salient waveform features. After that, the Coordinate Attention mechanism is employed to enhance the localization of salient waveform features by emphasizing the position of salient waveforms and the spatial relationship across the entire frequency spectrum. Finally, the obtained features are accessed to the fully connected for sleep staging. The model was validated with a 20-fold cross-validation procedure on two public available datasets, and the overall accuracy, kappa coefficient, and MF1 score reached 92.9%, 78.7, 0.86 and 90.0%, 75.8, 0.80 on Sleep-EDF-20 and Sleep-EDFx, respectively. Experimental results show that the proposed model achieves competitive performance for sleep staging compared with the reported approaches under the identical conditions.

AIE fluorescent probe based on tetraphenylethylene and morpholine-thiourea structures for detection of HClO.

As an important signal molecule in the living body, hypochlorous acid (HClO) participates in various physiological processes. However, excessive hypochlorous acid will cause some oxidative damage. The organic aggregation-induced emission luminogens (AIEgens) based on tetraphenylethylene (TPE) structures have recently become research hotspots as fluorescent probe materials. In this paper, a kind of water-soluble fluorescent probe TPE-M based on TPE and morpholine-thiourea structures were designed and synthesized for the detection of HClO. Due to the introduction of morpholine structures, the TPE-M showed excellent water solubility. The fluorescence properties of the TPE-M were strongly affected by the polarity of the solvent. Besides, the cation-anion and reactive oxygen species recognition experiments indicated that the fluorescent probe TPE-M displayed a single recognition characteristic for HClO because of the existence of thiourea structures. The limit of detection for HClO was calculated to be 0.25 µM. The particle size distribution measurement under the water phase revealed that the particle size of the TPE-M was mainly centered at 150 nm. The recognition mechanism of HClO by the probe TPE-M was proposed and explained by mass spectra and Gaussian calculation. Furthermore, a cell imaging experiment proved that the TPE-M probe successfully detected HClO in Hela cells.

Application of polymerized porcine hemoglobin in the ex vivo normothermic machine perfusion of rat livers.

Background: In contrast to traditional static cold preservation of donor livers, normothermic machine perfusion (NMP) may reduce preservation injury, improve graft viability and potentially allows ex vivo assessment of graft viability before transplantation. The polymerized porcine hemoglobin is a kind of hemoglobin oxygen carrier prepared by crosslinking porcine hemoglobin by glutaraldehyde to form a polymer. The pPolyHb has been proved to have the ability of transporting oxygen which could repair the organ ischemia-reperfusion injury in rats. Objective: In order to evaluate the effectiveness of rat liver perfusion in vitro based on pPolyHb, we established the NMP system, optimized the perfusate basic formula and explored the optimal proportion of pPolyHb and basal perfusate. Methods: The liver was removed and perfused for 6 h at 37°C. We compared the efficacy of liver perfusion with different ratios of pPolyHb. Subsequently, compared the perfusion effect using Krebs Henseleit solution and pPolyHb perfusate of the optimal proportion, and compared with the liver preserved with UW solution. At 0 h, 1 h, 3 h and 6 h after perfusion, appropriate samples were collected for blood gas analysis and liver injury indexes detection. Some tissue samples were collected for H&E staining and TUNEL staining to observe the morphology and detect the apoptosis rate of liver cells. And we used Western Blot test to detect the expression of Bcl-2 and Bax in the tissues. Results: According to the final results, the optimal addition ratio of pPolyHb was 24%. By comparing the values of Bcl-2/Bax, the apoptosis rate of pPolyHb group was significantly reduced. Under this ratio, the results of H&E staining and TUNEL staining showed that the liver morphology was well preserved without additional signs of hepatocyte ischemia, biliary tract injury, or hepatic sinusoid injury, and hepatocyte apoptosis was relatively mild. Conclusion: Through the above-mentioned study we show that within 6 h of perfusion based on pPolyHb, liver physiological and biochemical activities may essentially be maintained in vitro. This study demonstrates that a pPolyHb-based perfusate is feasible for NMP of rat livers. This opens up a prospect for further research on NMP.

Ursolic Acid Protects Neurons in Temporal Lobe Epilepsy and Cognitive Impairment by Repressing Inflammation and Oxidation.

Temporal lobe epilepsy (TLE) is characterized as an impaired ability of learning and memory with periodic and unpredictable seizures. Status epilepticus (SE) is one of the main causes of TLE. Neuroinflammation and oxidative stress are directly involved in epileptogenesis and neurodegeneration, promoting chronic epilepsy and cognitive deficit. Previous studies have shown that ursolic acid (UA) represses inflammation and oxidative stress, contributing to neuroprotection. Herein, we demonstrated that UA treatment alleviated seizure behavior and cognitive impairment induced by epilepsy. Moreover, UA treatment rescued hippocampal neuronal damage, aberrant neurogenesis, and ectopic migration, which are commonly accompanied by epilepsy occurrence. Our study also demonstrated that UA treatment remarkably suppressed the SE-induced neuroinflammation, evidenced by activated microglial cells and decreased inflammation factors, including TNF-α and IL-1ß. Likewise, the expression levels of oxidative stress damage markers and oxidative phosphorylation (OXPHOS) enzyme complexes of mitochondria were also remarkably downregulated following the UA treatment, suggesting that UA suppressed the damage caused by the high oxidative stress and the defect mitochondrial function induced by SE. Furthermore, UA treatment attenuated GABAergic interneuron loss. In summary, our study clarified the notable anti-seizure and neuroprotective properties of UA in pilocarpine-induced epileptic rats, which is mainly achieved by abilities of anti-inflammation and anti-oxidation. Our study indicates the potential advantage of UA application in ameliorating epileptic sequelae.

Photoluminescence, thermal and surface properties of triarylimidazole-containing polyimide nanocomposite films.

In this work, a triarylimidazole-containing diamine 2-(4-methylphenyl)-4,5-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (MPBAI) was firstly synthesized and polymerized with 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) to prepare transparent polyimide (PI) films by means of thermal imidization. Then, inorganic nanoparticles including silica (SiO2), alumina (Al2O3) and silicon nitride (Si3N4) were separately introduced into the PI(MPBAI-CBDA) with different mass fractions of 0.02%, 0.10%, 0.50% and 2.50% to obtain three series of PI nanocomposite films. All these films were close to colorless and transparent, although the light transmittance showed a downward trend due to the introduction of nanoparticles. Moreover, as the content of inorganic nanoparticles increased, the fluorescence intensities of these films were increased. Comparatively, the improvement effect of nano-SiO2 was the most obvious. When the content of SiO2 was 2.50%, the maximum intensity of the fluorescence absorption peak was increased by 9.6 times, and the absolute fluorescence quantum yield reached 17.2%, about 5.2 times that of the original PI film. Moreover, the maximum absorption peak produced a red shift of 85 nm due to the addition of 2.50% Si3N4, which was probably caused by the weakening of fluorescence quenching effect and high permittivity. The nanocomposites exhibited high glass transition temperatures of around 300 °C and excellent thermal stabilities. The surface hydrophobicity was changed by adjusting the mass and type of nanoparticles. Thus, this work provided a simple way to improve the photoluminescence effect by introducing the nanoparticles. The functional films will be expected to be applied in some optical applications.

Enhanced gas separation and mechanical properties of fluorene-based thermal rearrangement copolymers.

A series of thermal rearrangement (TR) copolymer membranes were prepared by the copolymerization of 9,9-bis(3-amino-4-hydroxyphenoxyphenyl) fluorene (BAHPPF), 9,9-bis(3-amino-4-hydroxyphenyl)fluorene (BAHPF) and 2,2'-bis(3,4'-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), followed by thermal imidization and further thermal rearrangement. The effects of molar ratio of diamines on the structure and properties of copolymer membranes were studied. The copolymer precursors CP-4:6 and CP-5:5 exhibited excellent mechanical properties. The mechanical properties of precursor membranes rapidly decreased with the increase of thermal treatment temperatures, but the tensile strength of TRCP-4:6 still reached 21.2 MPa. In general, the gas permeabilities of TR copolymers increased with the increase of BAHPF content. Comparatively, TRCP-3:7 and TRCP-4:6 showed higher gas permeabilities, coupled with high O2/N2 and CO2/CH4 selectivities. Especially, the H2, CO2, O2, N2 and CH4 permeabilities of TRCP-4:6 reached 244.4, 269.0, 46.8, 5.20 and 4.60 Barrers respectively, and the selectivities for CO2/CH4 and O2/N2 were 58.48 and 9.00, which exceeded the 2008 upper bound. Therefore, these TR copolymer membranes are expected to be one of the candidate materials for gas separation applications.

Phthalide-containing poly(ether-imide)s based thermal rearrangement membranes for gas separation application.

The diamine monomer 3,3-bis[4-(3-hydroxy-4-amino-phenoxy)phenyl]phthalide (BHAPPP) was firstly synthesized by the nucleophilic substitution of 5-fluoro-2-nitrophenol and phenolphthalein, followed by a reduction reaction. A series of phthalide-containing poly(ether imide)s (PEI) were then prepared through the polycondensation of BHAPPP with six kinds of dianhydrides, including 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic dianhydride (ODPA), 1,2,3,4-cyclobutane tetracarboxylic dianhydride (CBDA) and pyromellitic dianhydride (PMDA), as well as thermal imidization. After further thermal treatment, the corresponding thermal rearrangement (TR) membranes were obtained. Due to the existence of the phthalide lactone ring, the PEIs probably underwent TR and crosslinking simultaneously. With the increase of thermal treatment temperature, the mechanical properties of the TR membranes dramatically decreased, but the gas separation properties obviously increased. When the PEIs were treated at 450 °C for 1 h, the CO2, H2, O2, N2 and CH4 permeability of TR(BHAPPP-6FDA) reached 258.5, 190.5, 38.35, 4.25 and 2.15 Barrers, respectively. Meanwhile, the CO2/CH4 selectivity of 120.2 sharply exceeded the 2008 Robeson limit, and O2/N2 selectivity was 9.02, close to the 2015 upper limit. Therefore, the TR membranes derived from phthalide-containing PEIs exhibit superior gas separation performance, andare expected to be applied in the field of gas separation.

Solubility, thermal and photoluminescence properties of triphenyl imidazole-containing polyimides.

In this paper, three kinds of triphenyl imidazole-containing diamines including 2-phenyl-4,5-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (PBAI), 2-(4-methylphenyl)-4,5-bis(4-(4-amino-2-trifluoromethyl phenoxy)phenyl)imidazole (MPBAI) and 2-(4-trifluoromethylphenyl)-4,5-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (TFPBAI) were synthesized. Then, a series of polyimide (PI) films were prepared by the solution polymerization of the three diamines and various dianhydrides, such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 1,2,4,5-pyromellitic dianhydride (PMDA) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), followed by thermal imidization. The effects of chemical structures on the solubilities and thermal, optical and electrochemical properties of polyimides were explored. All the polyimides exhibited higher glass transition temperatures around 300 °C and excellent solubilities in common polar solvents. The polyimide films derived from CBDA or 6FDA showed better optical properties with light color and transparent characteristics. The fluorescence test showed that the photoluminescence color of CBDA-based polyimide films is in the blue range in the CIE 1931 spectrum, while the polyimide film based on PMDA and 6FDA presented black or weak yellow light. However, all these polyimides in solution exhibited similar blue luminescence. Electrochemical tests indicated that the HOMO and LUMO values of these films were around -6.5 and -3.6 eV, and the energy gap difference was about 3.0 eV. Therefore, the triphenyl imidazole-containing polyimides exhibit comprehensive performance, which will be expected as a new kind of functional material for certain application in the optical and optoelectronics fields.

Effect of Modified Cardanol as Secondary Plasticizer on Thermal and Mechanical Properties of Soft Polyvinyl Chloride.

This study represents the first attempt to prepare a novel cardanol-based plasticizer. Modified cardanol (MC, i.e., phosphorylated cardanol) containing nitrogen and phosphoric acid groups was synthesized and then incorporated into polyvinyl chloride (PVC) as the secondary plasticizer for partial substitution of dioctyl phthalate (DOP). The molecular structure of MC was characterized by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR), and 31P NMR spectroscopy. The thermal degradation behavior, mechanical performance, and compatibility of MC were also investigated. The substitution of DOP with MC enables PVC blends to have higher thermal stability, tensile strength, and leaching resistance. The tensile strength is increased from 17.7 MPa for DOP/PVC blend (MC-0) to 25.7 MPa for MC/PVC blend (MC-4), and the elongation at break is increased from 256 to 432%, respectively. The microstructure of the tensile fractured surface was studied by scanning electron microscopy. The results show that the addition of MC allows PVC blends to have well-balanced properties of flexibility and strength and excellent migration resistance.

Effects of α-zirconium phosphate and zirconium organophosphonate on the thermal, mechanical and flame retardant properties of intumescent flame retardant high density polyethylene composites.

The combination of synergistic agents with intumescent flame retardants (IFRs) is an excellent strategy for the development of high-performance flame retardant composites. Zirconium-based compounds are multifunctional materials with applications in various fields. In this study, zirconium-based compounds were synthesized and then combined with an IFR composed of ammonium polyphosphate (APP) and tris (2-hydroxyethyl) isocyanurate (THEIC) to prepare flame retardant high density polyethylene (HDPE) composites. α-Zirconium phosphate (α-ZrP) and two organic-inorganic hybrids (zirconium organophosphonate), Zr-ATMP and Zr-PA, were prepared using amino tri (methylene phosphonic acid) (ATMP) and phytic acid (PA), respectively, and their thermal, mechanical and flame retardant properties were characterized by thermogravimetric analysis, tensile test, limiting oxygen index (LOI) measurement and cone calorimetry test. The results showed that the LOI value of HD/IFR/Zr-ATMP composite reached a maximum of 26.2% using 25 wt% of flame retardant containing 3 wt% of Zr-ATMP. Of the three zirconium-based compounds, Zr-ATMP and α-ZrP can reduce the peak heat release rate compared with the composite containing only IFR. However, zirconium-based compounds showed no significant improvement of tensile strength.

Synthesis and gas permeation properties of thermally rearranged poly(ether-benzoxazole)s with low rearrangement temperatures.

The diamine monomer, 9,9-bis[4-(4-amino-3-hydroxylphenoxy)phenyl] fluorene (bis-AHPPF) was successfully synthesized according to our modified method. A series of hydroxyl-containing poly(ether-imide)s (HPEIs) were prepared by polycondensation of the bis-AHPPF diamine with six kinds of dianhydrides, including 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyl tetracarboxylic diandhydride (BPDA), 3,3',4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-(hexafluoroisopropylidine)diphtalic anhydride (6FDA) followed by thermal imidization. The corresponding thermally rearranged (TR) membranes were obtained by solid state thermal treatment at high temperature under a nitrogen atmosphere. The chemical structure, and physical, thermal and mechanical properties of the HPEI precursors were characterized. The effects of heat treatment temperature and dianhydrides on the gas transport properties of the poly(ether-benzoxazole) (PEBO) membranes were also investigated. It was found that these HPEIs showed excellent thermal and mechanical properties. All the HPEI precursors underwent thermal conversion in a N2 atmosphere with low rearrangement temperatures. The gas permeabilities of the PEBO membranes increased with the increase of thermal treatment temperature. When HPEI-6FDA was treated at 450 °C for 1 h, the H2, CO2, O2 and N2 permeabilities of the membrane reached 239.6, 196.04, 46.41 and 9.25 Barrers coupled with a O2/N2 selectivity of 5.02 and a CO2/N2 selectivity of 21.19. In six TR-PEBOs, PEBO-6FDA exhibited the lowest rearrangement temperature and largest gas permeabilities. Therefore, thermally rearranged membranes from bis-AHPPF-based HPEIs are expected to be promising materials for gas separation.

Genome sequencing analysis of a family with a child displaying severe abdominal distention and recurrent hypoglycemia.

BACKGROUND: Germline mutations in PTEN are associated with the PTEN hamartoma tumor syndrome (PHTS), an umbrella term used to describe a spectrum of autosomal-dominant disorders characterized by variable phenotypic manifestations associated with cell or tissue overgrowth. We report a boy who developed severe progressive abdominal distention due to a dramatic adipose mass from the age of 7 months and developed recurrent hypoinsulinemic hypoglycemia that led to seizures at the age of 4 years. METHODS: Trio-based whole-genome sequencing was performed by using blood DNA from the child and his parents. The possible pathogenic variants were verified by Sanger sequencing. Functional characterization of the identified variant was completed by western blot. RESULTS: The child inherited a single-nucleotide deletion NM_000314.6:c.849delA (p.Glu284Argfs) in the tumor suppressor gene PTEN from his father. The paternal family members have a history of cancer. It is conceivable that PTEN loss-of-function induced the adipose tumor growth and hypoglycemia, although the proband did not meet the usual diagnosis criteria of Cowden syndrome or Bannayan-Riley-Ruvalcaba syndrome that are characterized by germline mutations of PTEN. CONCLUSION: This case underlines the variability of phenotypes associated with PTEN germline mutations and provides useful information for diagnosis and genetic counseling of PTEN-related diseases for pediatric patients.

Downregulation of survivin and activation of caspase-3 through the PI3K/Akt pathway in ursolic acid-induced HepG2 cell apoptosis.

Ursolic acid (UA), a naturally occurring pentacyclic triterpene, is a potent in-vitro anticancer agent, acting through control of growth, apoptosis and differentiation. As the mechanism of its proapoptotic effects on human hepatocellular carcinoma cells has not been extensively studied, we performed an in depth evaluation of the effects of UA on apoptosis in human HepG2 cells. UA was found to inhibit the proliferation of HepG2 cells in a concentration and time-dependent manner. After treatment, cells showed evidence of activation of apoptosis, including the presence of apoptotic bodies and DNA fragmentation. UA-induced apoptosis was accompanied by a significant decrease in bcl-2 and survivin expression, with the corresponding ratio of bax/bcl-2 increased. The treatment with UA also increased the protein level and enzymatic activity of caspase-3. Z-DEVD-fmk, a specific caspase-3 inhibitor, significantly inhibited both the cytotoxic effect and the DNA fragmentation induced by UA, demonstrating the requirement for caspase-3 activity in UA-induced apoptosis. Inactivation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway was also involved, as inhibition of PI3K by LY294002 significantly increased UA-induced apoptosis. Kinetic experiments indicated that UA downregulated PI3K/p85 subunit (PI3K/p85) and phospho-Akt, before downregulating survivin. The further results also confirmed that LY294002 not only downregulated survivin alone, but considerably enhanced the repression of survivin combined with UA. UA therefore seemed to downregulate the expression of survivin by blocking PI3K/Akt. Taken together, the data suggest that the proapoptotic effect of UA on HepG2 cells is mediated by activation of caspase-3, and is highly correlated with inactivation of PI3K/Akt/survivin pathway.

Survivin gene RNA interference induces apoptosis in human HL60 leukemia cell lines.

BACKGROUND: It has been demonstrated that survivin, a member of the inhibitor of apoptosis (IAP) protein family, is expressed in human cancers but is undetectable in normal differentiated tissues. HL60 siRNA was introduced into HL60 cells to investigate its effect on cancer cell growth. METHODS: The opposite livability on HL60 cells was assayed with an MTT test. The change of mRNA and protein of the survivin gene were detected by reverse transcriptase polymerase chain reaction and Western blot, respectively. Cell apoptosis was assayed by flow cytometry. RESULTS: The growth of HL60 cells decreased by 65.3%, 62.1%, and 52.4% when they transfected with 400 nM siRNA lyh1, lyh2, and lyh3 after 48 hours, in comparison to the control group. Also, the mRNA and protein were knocked down and HL60 cells presented an increase in apoptosis index. CONCLUSIONS: Small interfering RNA can exert a knockdown of survivin gene expression in HL60 cells, and effectively induce apoptosis and inhibit the growth of leukemia cells.

[A universal high-throughput novel method of constructing the vectors].

In this paper, a simple universal high-throughput method of constructing the vectors was developed. It could add proper adapter when the PCR primers were designed, and the purpose fragments were cloned by PCR, and the various complementary sticky ends were created by T4 DNA polymerase's 3' -exodeoxyribonuclease activity. If all these fragments were put together with DNA ligase, they would recombinate in an orientation. If they had been transformated, the tansformants would be identified. Let's take the Oryza sativa single-cross homologous recombination chloroplast expression vector pRSMGA which was constructed with seven fragments as an example, if the vector pRSMGA was constructed in using the method what had mentioned, only twice recombination and transformation would be done. Scores of experiments had proved that it is a simple universal high-throughput novel method to construct the complicated vectors, which has not appeared in the periodical.