Docosahexaenoic Acid Reverses Epithelial-Mesenchymal Transition and Drug Resistance by Impairing the PI3K/AKT/ Nrf2/GPX4 Signalling Pathway in Docetaxel-Resistant PC3 Prostate Cancer Cells

Drug resistance is a serious problem in cancer therapy. Growing evidence has shown that docosahexaenoic acid has anti-inflammatory and chemopreventive abilities. Studies have shown that autophagy inhibition and ferroptosis are promising therapeutic strategies for overcoming multidrug resistance. This study was aimed to examine whether docosahexaenoic acid (DHA) could reverse docetaxel resistance in prostate cancer cells. Cell survival was examined by MTT and colony formation. Protein expression was determined by Western blot. Reactive oxygen species (ROS) production was measured by flow cytometry. DHA displayed anti-cancer effects on proliferation, colony formation, migration, apoptosis, autophagy and epithelial mesenchymal transition. Glutathione-S-transferase π is an enzyme that plays an important role in drug resistance. DHA inhibited GSTπ protein expression and induced cytoprotective autophagy by regulating the PI3K/AKT signalling pathway in PC3R cells. DHA combined with PI3K inhibitor (LY294002) enhanced apoptosis by alleviating the expression of LC3B, (pro-) caspase- 3 and (uncleaved) PARP. DHA induced ferroptosis by attenuating the expression of glutathione peroxidase 4 (GPX4) and nuclear erythroid 2-related factor 2 (Nrf2). DHA-treated PC3R cells produced ROS. The ROS and cytotoxicity were reversed by treatment with ferrostatin-1. DHA combined with docetaxel inhibited EMT by regulating the expression of E-cadhein and N-cadherin. In summary, DHA reversed drug resistance and induced cytoprotective autophagy and ferroptosis by regulating the PI3K/AKT/Nrf2/GPX4 signalling pathway in PC3R cells. We propose that DHA could be developed as a chemosensitizer and that the PI3K/AKT /Nrf2/GPX4 signalling pathway might be a promising therapeutic target for overcoming cancer drug resistance.

Potassium channels and their role in glioma: A mini review

K⁺ channels regulate a multitude of biological processes and play important roles in a variety of diseases by controlling potassium flow across cell membranes. They are widely expressed in the central and peripheral nervous system. As a malignant tumor derived from nerve epithelium, glioma has the characteristics of high incidence, high recurrence rate, high mortality rate, and low cure rate. Since glioma cells show invasive growth, current surgical methods cannot completely remove tumors. Adjuvant chemotherapy is still needed after surgery. Because the blood-brain barrier and other factors lead to a lower effective concentration of chemotherapeutic drugs in the tumor, the recurrence rate of residual lesions is extremely high. Therefore, new therapeutic methods are needed. Numerous studies have shown that different K⁺ channel subtypes are differentially expressed in glioma cells and are involved in the regulation of the cell cycle of glioma cells to arrest them at different stages of the cell cycle. Increasing evidence suggests that K⁺ channels express in glioma cells and regulate glioma cell behaviors such as cell cycle, proliferation and apoptosis. This review article aims to summarize the current knowledge on the function of K⁺ channels in glioma, suggests K⁺ channels participating in the development of glioma.

Restoration of S100A4 expression enhances invasive and metastatic potentials of COLO16 cutaneous squamous cancer cells

BACKGROUND

S100A4 promotes cancer metastasis but is frequently silenced in human cutaneous squamous cell carcinomas/c-SCCs due to DNA methylation, which may explain the less metastasized property of c-SCCs.

OBJECTIVE

This study aims to check 1) whether the metastatic potential of S100A4-negative human c-SCC cells could be enhanced when S100A4 expression is restored in COLO16 c-SCC cells with S100A4 methylation and 2) the correlation of S100A4 expression and the differentiation grades and invasiveness of human c-SCC tumors.

METHODS

The motility and invasion of parent and transfected COLO16 cells are examined by the use of 24-well modified Boyden chambers, scratched wound healing assay and nude mouse transplantation tumor model. Meanwhile, the correlation of S100A4 expression with growth patterns and grade of differentiation of c-SCC surgical specimens are analyzed.

RESULTS

S100A4 expression is successfully restored in COLO16 cells after plasmid lipofectamine transfection. Transwell and scratched wound healing assays shows that the invasion and migration activities of S100A4-expressing transfectants are higher than that of parent COLO16 cells. Subcutaneous and foot pad c-SCC models are established by injecting 5 × 10<formula>^{6}</formula>/100~l parental and S100A4-expressing COLO16 cells to BALB/c-nu/nude mice, respectively. Histological examination confirms the differences of invasiveness between the parent cells and the transfectants. Regional lymph node metastases are found only in the mice bearing S100A4-expressing tumors. S100A4 expression levels and frequencies are significantly different (P< 0.001) between the well and the poorly differentiated c-SCCs and closely correlated with tumor invasion (P< 0.05).

CONCLUSIONS

S100A4 confers invasive and metastatic potentials on human c-SCCs. The low incidence of metastasis of c-SCCs, especially the well differentiated ones, might be due to the infrequent S100A4 expression. S100A4 can be regarded as a negative prognostic biomarker or a metastasis-risk factor of human c-SCCs.

Orientation and surface activity of Janus particles at fluid-fluid interfaces

We study the influence of shape of Janus particles on their orientation and surface activity at fluid-fluid interfaces via molecular dynamics simulations. The Janus particles are characterized by two regions with different wettability divided along their major axes. Three types of Janus particles are considered: Janus spheres, Janus rods, and Janus disks. We find that Janus spheres and Janus rods prefer one orientation at the interface, regardless of the surface property. In contrast, Janus disks can adopt one of two orientations when adhered to a fluid-fluid interface: one orientation corresponds to the equilibrium state and the other is a kinetically trapped metastable state. The orientation of Janus disks strongly depends on the disk characteristics, such as their size, aspect ratio, and surface property. Furthermore, we find that changes in the shape of Janus particles strongly influence the interfacial tension at the fluid-fluid interface. According to the time evolution of the interfacial tension, the adsorption of Janus particles is characterized by three adsorption stages based on different surface activities and adsorption kinetics depending on the particle shape.

Relaxation dynamics in a binary hard-ellipse liquid

Structural relaxation in binary hard spherical particles has been shown recently to exhibit a wealth of remarkable features when size disparity or mixture composition is varied. In this paper, we test whether or not similar dynamical phenomena occur in glassy systems composed of binary hard ellipses. We demonstrate via event-driven molecular dynamics simulation that a binary hard-ellipse mixture with an aspect ratio of two and moderate size disparity displays characteristic glassy dynamics upon increasing density in both the translational and the rotational degrees of freedom. The rotational glass transition density is found to be close to the translational one for the binary mixtures investigated. More importantly, we assess the influence of size disparity and mixture composition on the relaxation dynamics. We find that an increase of size disparity leads, both translationally and rotationally, to a speed up of the long-time dynamics in the supercooled regime so that both the translational and the rotational glass transition shift to higher densities. By increasing the number concentration of the small particles, the time evolution of both translational and rotational relaxation dynamics at high densities displays two qualitatively different scenarios, i.e., both the initial and the final part of the structural relaxation slow down for small size disparity, while the short-time dynamics still slows down but the final decay speeds up in the binary mixture with large size disparity. These findings are reminiscent of those observed in binary hard spherical particles. Therefore, our results suggest a universal mechanism for the influence of size disparity and mixture composition on the structural relaxation in both isotropic and anisotropic particle systems.

MDA-7/IL-24 suppresses tumor adhesion and invasive potential in hepatocellular carcinoma cell lines

Melanoma differentiation associated gene-7 (MDA-7)/interleukin‑24 (IL-24) has been considered as a tumor-suppressor gene, which suppresses the growth and induces the apoptosis of cancer cells. In the present study, we investigated the effect and mechanisms of MDA-7/IL-24 regarding the inhibition of metastasis of HepG2 and BEL-7402 human hepatocellular carcinoma (HCC) cells in vitro. We established MDA-7/IL-24-overexpressing HepG2 and BEL-7402 cell lines and found that MDA-7/IL-24 overexpression inhibited tumor cell adhesion and invasion, and induced G2/M arrest in tumor cells. To explore its mechanism of action, western blotting and real-time-PCR assay were used to investigate the expression of E-cadherin, CD44, ICAM-1, matrix metalloproteinase (MMP)-2 and -9, CyclinB, Twist, survivin, p-ERK and p-Akt. ELISA assay was used to measure the secretion of TGF-β, and a reporter gene assay was used to detected the transcriptional activity of NF-κB and AP-1 in HepG2 and BEL-7402 cells. The results showed that MDA-7/IL-24 overexpression decreased the expression of CD44, ICAM-1, MMP-2/-9, CyclinB, Twist, survivin, TGF-β and p-Akt, transcriptional activity of NF-κB, and increased the expression of E-cadherin and p-ERK and transcriptional activity of AP-1 in HepG2 and BEL-7402 cells. Our results revealed that MDA-7/IL-24 mediated the inhibition of adhesion and invasion in HepG2 and BEL-7402 cells by suppressing metastasis-related gene expression. Thus, MDA-7/IL-24 may be used as a novel cancer-suppressor gene for the therapy of human HCC.

Catalpol inhibits LPS plus IFN-γ-induced inflammatory response in astrocytes primary cultures

A large body of evidence suggests that the inflammatory reaction plays an important role in the pathogenesis of neurodegenerative diseases. Our previous studies described the neuroprotective effects of catalpol in lipopolysaccharide (LPS)-induced inflammatory models, in which catalpol was shown to prevent mesencephalic neuron death and ameliorate cognitive ability animals. To further investigate the protective effect and underlying mechanism of catalpol, astrocytes were pretreated with low (0.1mM) and high dose (0.5mM) catalpol for 1h prior to LPS plus interferon-γ stimulation. Biochemical analyses showed that NO and ROS production and iNOS activity were significantly reduced by catalpol. Data at transcriptional level also demonstrated that catalpol potently attenuated gene expressions involved in inflammation, such as iNOS, COX-2 and TLR4. In addition, our exploration further revealed that the suppressive action of catalpol on inflammation was mediated via inhibiting nuclear factor-κB (NF-κB) activation. Collectively, these results suggest that catalpol can exert inhibitory effects on the inflammatory reaction in astrocytes and that inactivation of NF-κB could be the major determinant for its anti-inflammatory mechanism. Therefore, catalpol may potentially be a highly effective therapeutic agent in treating neurodegenerative diseases associated with inflammation.

Effect of attractions on correlation length scales in a glass-forming liquid

There is growing evidence that slow dynamics and dynamic heterogeneity possess structural signatures in glass-forming liquids. However, even in the weakly frustrated glass-forming liquids, whether or not the dynamic heterogeneity has a structural origin is a matter of debate. Via molecular dynamics simulation, we present a study of examining the connection between dynamic heterogeneity and bond orientational order in a weakly frustrated glass-forming liquid in two dimensions by taking advantage of assessing the effect of attractions on the correlation length scales. We find that attractions can strongly affect relaxation dynamics, dynamic heterogeneity, and the associated dynamic correlation length of the liquid, but their influence on bond orientational order and the associated static correlation length shows a manner reminiscent of the effect of attractions on the thermodynamics of liquids. This implies that the growth of bond orientational order and static correlation length scale might be merely a manifestation of favoring the configurational entropy in weakly frustrated glass-forming liquids. Thus, our results provide strong evidence that bond orientational order cannot provide a complete description of dynamic heterogeneity even in weakly frustrated glass-forming systems.

Dynamics and correlation length scales of a glass-forming liquid in quiescent and sheared conditions

We numerically study dynamics and correlation length scales of a colloidal liquid in both quiescent and sheared conditions to further understand the origin of slow dynamics and dynamic heterogeneity in glass-forming systems. The simulation is performed in a weakly frustrated two-dimensional liquid, where locally preferred order is allowed to develop with increasing density. The four-point density correlations and bond-orientation correlations, which have been frequently used to capture dynamic and static length scales ξ in a quiescent condition, can be readily extended to a system under steady shear in this case. In the absence of shear, we confirmed the previous findings that the dynamic slowing down accompanies the development of dynamic heterogeneity. The dynamic and static length scales increase with α-relaxation time τ(α) as a power law [Formula: see text], with μ > 0. In the presence of shear, both viscosity and τ(α) have power-law dependences on shear rate in the marked shear-thinning regime. However, the dependence of correlation lengths cannot be described by power laws in the same regime. Furthermore, the relation [Formula: see text] between length scales and dynamics holds for not too strong shear where thermal fluctuations and external forces are both important in determining the properties of dense liquids. Thus, our results demonstrate a link between slow dynamics and structure in glass-forming liquids even under nonequilibrium conditions.

Isolation of choline monooxygenase (CMO) gene from Salicornia europaea and enhanced salt tolerance of transgenic tobacco with CMO genes

Glycinebetaine (GB) is an osmoprotectant accumulated by certain plants in response to high salinity, drought, and cold stress. Plants synthesize GB via the pathway choline --> betaine aldehyde --> glycinebetaine, and the first step is catalyzed by choline monooxygenase (CMO). In the present study, by using RT-PCR and RLM-RACE, a full-length CMO cDNA (1844 bp) was cloned from a halophyte Salicornia europaea, which showed high homology to other known sequences. In order to identify its function, the ORF of CMO cDNA was inserted into binary vector PBI121 to construct the chimeric plant expression vector PBI121-CMO. Using Agrobacterium (LBA4404) mediation, the recombinant plasmid was transferred into tobacco (Nicotiana tabacum). The PCR, Southern blot and RT-PCR analysis indicated the CMO gene was integrated into the tobacco genome, as well as expressed on the level of transcription. The transgenic tobacco plants were able to survive on MS medium containing 300 mmol/L NaCl and more vigorous than those of wild type with the same concentration salt treatment. In salt-stress conditions, transgenic plants had distinctly higher chlorophyll content and betaine accumulation than that of the control, while relative electrical conductivity of transgenic plants was generally lower. The results suggested the CMO gene transformation could effectively contribute to improving tobacco salt-resistance.

Protection of PC12 cells against superoxide-induced damage by isoflavonoids from Astragalus mongholicus

OBJECTIVE

To further investigate the neuroprotective effects of five isoflavonoids from Astragalus mongholicus on xanthine (XA)/ xanthine oxidase (XO)-induced injury to PC12 cells.

METHODS

PC12 cells were damaged by XA/XO. The activities of antioxidant enzymes, MTT, LDH, and GSH assays were used to evaluate the protection of these five isoflavonoids. Contents of Bcl-2 family proteins were determined with flow cytometry.

RESULTS

Among the five isoflavonoids including formononetin, ononin, 9, 10-dimethoxypterocarpan-3-O-beta-D-glucoside, calycosin and calycosin-7-O-glucoside, calycosin and calycosin-7-O-glucoside were found to inhibit XA/ XO-induced injury to PC12 cells. Their EC50 values of formononetin and calycosin were 0.05 microg/mL. Moreover, treatment with these three isoflavonoids prevented a decrease in the activities of antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), while formononetin and calycosin could prevent a significant deletion of GSH. In addition, only calycosin and calycosin-7-O-glucoside were shown to inhibit XO activity in cell-free system, with an approximate IC50 value of 10 microg/mL and 50 microg/mL. Formononetin and calycosin had no significant influence on Bcl-2 or Bax protein contents.

CONCLUSION

Neuroprotection of formononetin, calycosin and calycosin-7-O-glucoside may be mediated by increasing endogenous antioxidants, rather by inhibiting XO activities or by scavenging free radicals.

Protective effects of catalpol against H2O2-induced oxidative stress in astrocytes primary cultures

It has been proposed that ROS production, including H(2)O(2), may lead to neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease. Catalpol, an iridoid glycoside, presents in the root of Rehmannia glutinosa, protects cells and mice from damage caused by a variety of toxic stimuli. In this study, we investigated whether catalpol could protect astrocytes from oxidant stress induced by H(2)O(2) because of the critical role of astrocytes in the brain and found the possible mechanism of protection. The results showed that catalpol could significantly increase the cell viability and reduce the intracellular ROS formation. Furthermore, catalpol attenuated H(2)O(2)-induced oxidative stress via preventing the decrease in the activities of antioxidant enzymes in glutathione redox cycling such as glutathione peroxidase, glutathione reductase and glutathione content. However, the catalase activity did not appear to be elevated by catalpol adequately. Together, the main mechanism underlying the protective effects of catalpol in H(2)O(2)-injured astrocytes might be related to the maintenance of glutathione metabolism balance and the decrease of ROS formation. Therefore, catalpol may be developed as a potential preventive or therapeutic drug for neurodegenerative diseases associated with oxidative stress.

Catalpol protects rat pheochromocytoma cells against oxygen and glucose deprivation-induced injury

OBJECTIVES

Catalpol has been identified to have neuroprotective effect on gerbils subjected to transient global cerebral ischemia. However, the mechanism that catalpol prevents ischemia is still unclear. In the present study, PC12 cells, exposed to oxygen and glucose deprivation (OGD) followed by reperfusion, were used as an in vitro model of ischemia. The protective effects of catalpol were investigated in ischemic-induced apoptosis in PC12 cells.

METHODS

After OGD for 3 hours and reoxygenation for 18 hours, cell survival was quantified by the reduction of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were determined using commercially available kits. Caspase-3 assay was performed using caspase-3 assay kit. Microplate reader was used to detect the intensities of rhodamine123 (Rh123) and reactive oxygen species (ROS). The level of Bcl-2 protein was measured by flow cytometry.

RESULTS

Catalpol attenuated ischemia-induced apoptotic death via preventing the decrease in the level of Bcl-2 protein and the activities of SOD and GSH-PX, inhibiting the reduction of mitochondrial membrane potential and suppressing activation of caspase-3.

DISCUSSION

The results suggest that the catalpol has the potential to prevent ischemic-induced apoptosis.

d-galactose administration induces memory loss and energy metabolism disturbance in mice: protective effects of catalpol

The neuroprotective effects of catalpol, an iridoid glycoside isolated from the fresh rehmannia roots, on the behavior and brain energy metabolism in senescent mice induced by d-galactose were assessed. Except control group, mice were subcutaneously injected with d-galactose (150 mg/kg body weight) for 6 weeks. From the fifth week, drug group mice were treated with catalpol (2.5, 5, 10 mg/kg body weight) and piracetam (300 mg/kg body weight) for the last 2 weeks. Behavioral changes including open field test and passive avoidance were examined after drug administration. To determine the brain damage, pathological alterations were measured by hematoxylin and eosin (HE) staining. The activities of lactate dehydrogenase (LDH), glutathione S-transferase (GSH-ST), glutamine synthetase (GS), creatine kinase (CK) in brain cortex and hippocampus were determined using different biochemical methods. Consistent with the cognition deficits, the activities of GSH-ST, GS and CK decreased while the activity of LDH increased in aging mice brain. Administration of catalpol for 2-weeks not only ameliorated cognition deficit, but also reversed the biochemical markers mentioned above and reduced the histological lesions in mouse brain. These results suggest that catalpol has protective effects on memory damage and energy metabolism failure in aging model mice and is worth testing for further preclinical study aimed for senescence or neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD).

Characterization and expression of a vacuolar Na(+)/H(+) antiporter gene from the monocot halophyte Aeluropus littoralis

Plant vacuolar Na(+)/H(+) antiporter plays an important role in salt tolerance. In order to understand the molecular basis of vacuolar Na(+)/H(+) antiporter responded to salinity and reveal a possible role of salt tolerance in monocots, a vacuolar Na(+)/H(+) antiporter gene (AlNHX) was isolated by reverse transcription-PCR and RNA ligase mediated rapid amplification of cDNA ends (RLM-RACE) based on the homology from Aeluropus littoralis (Gouan) Parl, a graminaceous halophyte. The AlNHX sequence contained 2706bp with an open read frame of 1623bp and the deduced transcripts encoding 540 amino acids shared a high homology with those putative vacuolar Na(+)/H(+) antiporters of higher plants. AlNHX was predicted containing ten putative hydrophobic regions, which was different with AtNHX1 and OsNHX1. DNA gel blot analysis indicated that there were two or three copies of AlNHX in the A. littoralis genome. The increased transcript levels of AlNHX were much higher in roots than that in shoots under salt stress. In addition, overexpression of AlNHX in tobacco conferred high salt tolerance to the transgenic plants. The analysis of ion contents indicated that under high salt stress for one month, the transgenic plants compartmentalized more Na(+) in the roots and kept a relative high K(+)/Na(+) ratio in the leaves compared with wild-type plants.

[Probe of the effect of Asp44 on the stability of myoglobin by circular dichroism spectropolarimeter]

To characterize the roles played by surface-charged residue Asp44 in the structure stability of horse heart myoglobin, the code of Asp44, GAT, in the gene of horse heart myoglobin was changed into AAA for Lys by PCR site-directed mutagenesis. The mutant gene was ligated into PstI/BamHI-cut pGYM and the resulting plasmid was transformed into E. coli BL21. The mutant protein (D44K) was expressed in BL21 successfully. The bacteria containing mutant myoglobin were treated with lysozyme. Then the mutant protein was purified by ammonium sulfate precipitation, ion-exchange chromatography and gel filtration. Circular dichroism spectra were employed to monitor the kinetic behaviors of wild-type and mutant myoglobins' denaturation at different pHs or upon heating, and the "two-state" model was used to simulate the kinetic process of wild-type and mutant myoglobins' denaturation upon heating to determine the unfolding thermodynamic parameters of Mb and its mutant (D44K). The results show that the mutation of the surface-charged residue Asp44 to Lys44 can increase the protein's stability on its resistance to heat, resulting in the increase in the protein's denaturing mid-temperature by about 4 degrees C, from 71.9 to 75.1 degrees C, but shows little effect on its resistance to acid denaturation.

First Report of a Pestalotiopsis sp. Causing Leaf Spot of Blueberry in China

In August 2006, leaf spots were observed on half-high blueberry (Vaccinium corymbosum) in a plant nursery in Dalian, China. The symptomatic potted 1-year-old blueberry plants were located in parts of a plant nursery with poor ventilation. The primary symptom was a leaf spot, 0.4 to 0.8 cm in diameter, with brown margins that enlarged and coalesced. Mycelium grew from symptomatic and green leaf tissue removed from the margin of a necrotic leaf spot. Plant tissues were surface disinfested with 0.1% mercuric chloride for 3 min and 70% ethyl alcohol for 30 s before plating onto potato dextrose agar. The resulting colonies were white with a regular margin and a rough surface. The cultures were covered with black and globular acervuli with a diameter of 100 to 200 μm. The base of each conidiophore was swollen and globose with phialides growing from the apical end. Mature conidia were straight to fusiform, measuring 19.0 to 27.5 × 6.3 to 9.2 μm, and five-celled with the three middle cells brown and darker than the end cells. The apical cell was triangular and hyaline with three simple setulae that were 17.2 to 29.7 μm long. The base cell terminated in a point 4.0 to 8.6 μm long. Koch's postulates were fulfilled for the fungus by spray inoculating two healthy young plants with 2 × 10⁵ conidia per ml of sterile distilled water. As a control, two similar plants were sprayed with sterile water. Plants were placed inside plastic bags to maintain humidity and incubated in a growth chamber at 26°C under fluorescent light for 14 h and at 20°C in darkness for 10 h. After 3 days, the plastic bags were removed and plants were maintained under the same conditions. More than 20 days after inoculation, symptoms on inoculated plants were similar to those previously described in the nursery. Control plants did not show any symptoms. Cultures isolated from the lesions were similar to those isolated previously from plants in the nursery. The morphological descriptions and measurements were similar to Pestalotiopsis clavispora (1). The 5.8S subunit and flanking internal transcribed spacers (ITS1 and ITS2) of rDNA and partial β-tubulin gene were amplified from DNA extracted from single-spore cultures using the ITS1/ITS4 and T1/Bt2b primers (2) respectively, and sequenced (GenBank Accession Nos. EF119336 and EF152585). The ITS sequences were most similar to the ITS regions of P. clavispora TA-8 (98%; GenBank Accession No. AY924264), P. clavispora TA-6 (98%; GenBank Accession No. AY924263), and P. clavispora PSHI 2002 Endo 389 (96%; GenBank Accession No. AY682929). The partial β-tubulin gene sequence was identical to Pestalotiopsis sp. isolate PSHI 2004 Endo 86 (100%; GenBank Accession No. DQ657901). The morphology and sequence data support the identity of the causal fungus as P. clavispora. To our knowledge, this is the first report on the presence of a Pestalotiopsis sp. causing a disease of blueberry in China. References: (1) E. F. Guba. Monograph of Monochaetia and Pestalotia. Harvard University Press, Cambridge, MA, 1961. (2) W. Tao et al. Mol. Cell Biol. 27:689, 2007.

Benzobijuglone, a novel cytotoxic compound from Juglans mandshurica, induced apoptosis in HeLa cervical cancer cells

A new quinone compound, p-hydroxymethoxybenzobijuglone (HMBBJ), isolated from Juglans mandshurica by bioassay-guided fractionation, showed cytotoxic activity against HeLa cell line. Its chemical structure was determined by NMR and HREIMS spectra. In this paper, its ability to induce apoptosis in HeLa cells was studied for the first time. After treated with HMBBJ, the growth of HeLa cells was inhibited and cells displayed typical morphological apoptotic characteristics. Data from flow cytometry analysis showed that the HeLa cell cycle was arrested in the G2/M phase by HMBBJ, and the apoptotic rate of HeLa cells increased in a dose-dependent manner. Meanwhile, HMBBJ increased the expression of caspase-8, -3 and Bax, decreased the expression of Bcl-2, and lowered the DeltaPsi(m). These findings reveal that HMBBJ could efficiently induce HeLa cells apoptosis through mitochondria dependent pathway and activation of the caspase cascade, and it may be a potential chemotherapeutic candidate for the treatment of cancer.

Study of self-assembly of symmetric coil-rod-coil ABA-type triblock copolymers by self-consistent field lattice method

The self-assembly of symmetric coil-rod-coil ABA-type triblock copolymer melts is studied by applying self-consistent field lattice techniques in a three-dimensional space. The self-assembled ordered structures differ significantly with the variation of the volume fraction of the rod component, which include lamellar, wave lamellar, gyroid, perforated lamellar, cylindrical, and spherical-like phases. To understand the physical essence of these phases and the regimes of occurrence, we construct the phase diagram, which matches qualitatively with the existing experimental results. Compared with the coil-rod AB diblock copolymer, our results revealed that the interfacial grafting density of the separating rod and coil segments shows important influence on the self-assembly behaviors of symmetric coil-rod-coil ABA triblock copolymer melts. We found that the order-disorder transition point changes from f(rod)=0.5 for AB diblock copolymers to f(rod)=0.6 for ABA triblock copolymers. Our results also show that the spherical-like and cylindrical phases occupy most of the region in the phase diagram, and the lamellar phase is found stable only at the high volume fraction of the rod.

Neuroprotective effect of catalpol against MPP+-induced oxidative stress in mesencephalic neurons

The neuroprotective effects of catalpol, an iridoid glycoside present in the roots of Rehmannia glutinosa, on 1-methyl-4-phenylpyridinium (MPP(+))-induced oxidative stress in cultured mesencephalic neurons, especially dopaminergic neurons, were investigated. Exposure of mesencephalic neurons to 10microM MPP(+) induced a leakage of lactate dehydrogenase (LDH) and decreased cell viability, measured with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Catalpol increased neuron viability and markedly attenuated MPP(+)-induced dopaminergic neuron death in a dose-dependent manner. In order to clarify the neuroprotective mechanism of catalpol, mitochondrial function, the activities of endogenous antioxidants and the lipid peroxide content were measured. The results indicated that catalpol prevented the MPP(+)-induced inhibition of complex I activity and the loss of mitochondrial membrane potential. In addition, catalpol reduced the content of lipid peroxide and increased the activity of glutathione peroxidase and superoxide dismutase. Taken together, the above results suggest that catalpol may be a candidate drug for the treatment of oxidative stress-induced neurodegenerative disease.

Stability of two-dimensional tessellation ice on the hydroxylated beta-cristobalite (100) surface

Monolayer adsorbed water on the beta-cristobalite (100) surface is studied via classical molecular dynamics simulations. The ordered two-dimensional (2D) tessellation ice structure (i.e., the four-membered and the eight-membered rings appear alternatively) is justified at low temperatures in the simulations. The stability of this possible new ice phase is further investigated by heating the system from 5 to 300 K. An order-disorder structural transition is observed between 100 and 200 K, featuring the melting process of the tessellation ice. This process is characterized by the water oxygen-oxygen radial distribution function, the coordination number, the distance vector between the center of mass of the oxygen and the hydrogen atoms in water, the mean square displacement of oxygen in water, and the vibrational density of state. The above techniques show consistency on that the order-disorder transition temperature of the 2D tessellation ice is far below 300 K. The 2D tessellation ice structure is also obtained via density functional calculations with different generalized gradient approximations. By comparing the calculated adsorption and the lateral energies between different methods, we find that the melting temperature of the specific 2D ice structure is strongly method dependent. Therefore, further experimental works are urged to justify this possible new ice phase and probe its stability.

Calculating the Equation of State Parameters and Predicting the Spinodal Curve of Isotactic Polypropylene/Poly(ethylene-co-octene) Blend by Molecular Dynamics Simulations Combined with Sanchez−Lacombe Lattice Fluid Theory

Molecular dynamics simulations are adopted to calculate the equation of state characteristic parameters P*, rho*, and T* of isotactic polypropylene (iPP) and poly(ethylene-co-octene) (PEOC), which can be further used in the Sanchez-Lacombe lattice fluid theory (SLLFT) to describe the respective physical properties. The calculated T* is a function of the temperature, which was also found in the literature. To solve this problem, we propose a Boltzmann fitting of the data and obtain T* at the high-temperature limit. With these characteristic parameters, the pressure-volume-temperature (PVT) data of iPP and PEOC are predicted by the SLLFT equation of state. To justify the correctness of our results, we also obtain the PVT data for iPP and PEOC by experiments. Good agreement is found between the two sets of data. By integrating the Euler-Lagrange equation and the Cahn-Hilliard relation, we predict the density profiles and the surface tensions for iPP and PEOC, respectively. Furthermore, a recursive method is proposed to obtain the characteristic interaction energy parameter between iPP and PEOC. This method, which does not require fitting to the experimental phase equilibrium data, suggests an alternative way to predict the phase diagrams that are not easily obtained in experiments. As an example, in the framework of SLLFT, the spinodal curve for the iPP/PEOC blend is predicted at the low molecular weights that are used in the simulations.

Efficacy of catalpol as protectant against oxidative stress and mitochondrial dysfunction on rotenone-induced toxicity in mice brain

Rotenone, a specific inhibitor of mitochondrial complex I, reproduces many features of Parkinson's disease. The aim of the study was carried out to investigate how rotenone affected the mitochondrial function and antioxidant/oxidant parameters of mouse striatum, and secondly, to evaluate the ameliorating effects of catalpol against rotenone-induced damage. Our results showed that rotenone induced significant changes in mitochondrial function such as complex I activity and mitochondrial membrane potential decreased, and enhanced antioxidant status as glutathione depletion, enzymatic (glutathione peroxidase and superoxide dismutase) disorders, and increased lipid peroxidation. Catalpol increased complex I, superoxide dismutase and glutathione peroxidase activities, reduced lipid peroxidation and loss of mitochondrial membrane potential in rotenone-treated mice. These in vivo data indicated that catalpol might have protection against deleterious mouse damage caused by rotenone.