Synthesis of Amides with Remote Stereocenters by Catalytic Asymmetric γ-Alkynylation of α,ß-Unsaturated Amides.

An iridium-catalyzed enantioselective hydroalkynylation of α,ß-unsaturated amides was described. The selectivity of this reaction is distinct from that observed in many catalytic hydroalkynylations of α,ß-unsaturated carbonyl compounds. It occurs selectively at the γ instead of the ß position. Preliminary mechanistic studies suggest that the reaction proceeds through alkene isomerization followed by hydroalkynylation. This method provides a straightforward route for the synthesis of amides with a remote stereocenter at the γ position.

Knockdown of Dynamitin in testes significantly decreased male fertility in Drosophila melanogaster.

Dynamitin (Dmn) is a major component of dynactin, a multiprotein complex playing important roles in a variety of intracellular motile events. We previously found that Wolbachia bacterial infection resulted in a reduction of Dmn protein. As Wolbachia may modify sperm in male hosts, we speculate that Dmn may have a function in male fertility. Here we used nosGal4 to drive Dmn knock down in testes of Drosophila melanogaster to investigate the functions of Dmn in spermatogenesis. We found that knockdown of Dmn in testes dramatically decreased male fertility, overexpression of Dmn in Wolbachia-infected males significantly rescued male fertility, indicating an important role of Dmn in inducing male fertility defects following Wolbachia infection. Some scattered immature sperm with late canoe-shaped head distributed in the end of Dmn knockdown testis and only about half mature sperm were observed in the Dmn knockdown testis relative to those in the control. Transmission electron microscopy (TEM) exhibited fused spermatids in cysts and abnormal mitochondrial derivatives. Immunofluorescence staining showed significantly less abundance of tubulin around the nucleus of spermatid and scattered F-actin cones to different extents in the individualization complex (IC) during spermiogenesis in Dmn knockdown testes, which may disrupt the nuclear condensation and sperm individualization. Since dynein-dynactin complex has been shown to mediate transport of many cellular components, including mRNAs and organelles, these results suggest that Dmn may play an important role in Drosophila spermiogenesis by affecting transport of many important cytoplasmic materials.

Determination of glutathione in apoptotic SMMC-7221 cells induced by xylitol selenite using capillary electrophoresis.

OBJECTIVE: To determine the glutathione (GSH) content in a human hepatoma cell line (SMMC-7221) treated with xylitol/selenite, providing a part of an investigation of its anti-cancer mechanisms. RESULTS: The nuclei of SMMC-7221 cells were stained with Hoechst 33258 in an apoptosis assay, and their morphology subsequently changed from circular to crescent shape. The calibration curve (r(2) = 0.992) was established, and GSH content markedly decreased after treated with 0.5 and 1 mg xylitol/selenite l(-1) for 12, 36 and 60 h (12 h: from 95.57 ± 19.57 to 29.09 ± 7.74 and 24.27 ± 11.15; 36 h: from 70.73 ± 11.35 to 19.54 ± 6.39 and 9.35 ± 6.69; 60 h: from 72.63 ± 16.94 to 7.432 ± 3.84 and 0). The depletion rate of GSH was more related to the concentration of xylitol/selenite than the treatment time (from 69.95 ± 1.87 to 100 % vs. 0.22 ± 0.2 to 100 %). CONCLUSIONS: Xylitol/selenite is a promising anti-cancer drug to induce apoptosis in SMMC-7221 cells. It may regulate the apoptosis through the co-action of multiple mechanisms related to GSH depletion.

Establishment and characterization of a novel cell line from midgut tissue of Helicoverpa armigera (Lepidoptera: Noctuidae).

The midgut of lepidopteran larvae serves as a target for many pathogens such as Bacillus thuringiensis (Bt). Cell lines originating from midgut tissues will be very helpful tools in many research fields. However, to date, no Bt-susceptible midgut-derived cell lines are available. Here, we reported that a novel cell line, designated as HNU-Ha-MG1, was established from midgut tissue of the fourth instar larvae of Helicoverpa armigera. This cell line grew well in Grace's insect cell culture medium supplemented with 10-15% fetal bovine serum. The shape of the most cells was round or polygonal, and some tended to aggregate to form multiple cell masses. The size of the cells was 13.8 ± 1.8 µm in diameter, and the maximum density reached (2.40 ± 0.15) × 10(6) cells/ml. The population doubling time during logarithmic growth phase was 58.6 ± 7.0 h at 28°C. The number of chromosomes was about 90-130, which exhibited typical chromosome characteristics of lepidopteran cell lines. The patterns of random amplified polymorphic DNA of the cell line were different from those of Sl-HP and Hi5 cell lines which were frequently used in our laboratory. 20-Hydroxyecdysterone induced apoptosis in a very small part of cells at 2 µg/ml but did not affect expression of autophagy-related protein 8 (Atg8) and its lipidation at 36 h post-treatment. The cell line was permissive to Autographa californica nuclear polyhedrosis virus (AcMNPV) and H. armigera nuclear polyhedrosis virus (HaSNPV). This cell line was found to be susceptible to activated Cry1C at the final concentration of 0.5-1.0 µg/ml but not to the activated Cry1Ac.

Enhanced liver functions of HepG2 cells in the alginate/xyloglucan scaffold.

A scaffold provides a framework and initial support for the cells to attach, proliferate and differentiate, and form an extracellular matrix (ECM) in tissue engineering. Here, xyloglucan (XG) was used as a new synthetic ECM for HepG2 cell attachment in alginate capsules. The effects of XG on HepG2 cells on adherent behavior, albumin secretion, ammonia elimination, cell proliferation and gene expression of Connexin 32 and epithelial-cadherin were investigated. Xyloglucan could also promote the HepG2 cell-matrix interactions and the cell clusters formation of HepG2 cells in three dimensional scaffold, thus enhance the liver-specific functions in the three-dimensional space.

Extraction of light trapped due to total internal reflection using porous high refractive index nanoparticle films.

TiO2 nanoparticle layers composed of columnar TiO2 nanoparticle piles separated with nanoscale pores were fabricated on the bottom surface of the hemispherical glass prism by performing gas phase cluster beam deposition at glancing incidence. The porosity as well as the refractive index of the nanoparticle layer was precisely tuned by the incident angle. Effective extraction of the light trapped in the substrate due to total internal reflection with the TiO2 nanoparticle layers was demonstrated and the extraction efficiency was found to increase with the porosity. An enhanced Rayleigh scattering mechanism, which results from the columnar aggregation of the nanoparticles as well as the strong contrast in the refractive index between pores and TiO2 nanoparticles in the nanoporous structures, was proposed. The porous TiO2 nanoparticle coatings were fabricated on the surface of GaN LEDs to enhance their light output. A nearly 92% PL enhancement as well as a 30% EL enhancement was observed. For LED applications, the enhanced light extraction with the TiO2 nanoparticle porous layers can be a supplement to the microscale texturing process for light extraction enhancement.

Role of transient receptor potential ion channels and evoked levels of neuropeptides in a formaldehyde-induced model of asthma in BALB/c mice.

OBJECTIVE: Asthma is a complex pulmonary inflammatory disease characterized by the hyper-responsiveness, remodeling and inflammation of airways. Formaldehyde is a common indoor air pollutant that can cause asthma in people experiencing long-term exposure. The irritant effect and adjuvant effect are the two possible pathways of formaldehyde promoted asthma. METHODOLOGY/PRINCIPAL FINDINGS: To explore the neural mechanisms and adjuvant effect of formaldehyde, 48 Balb/c mice in six experimental groups were exposed to (a) vehicle control; (b) ovalbumin; (c) formaldehyde (3.0 mg/m(3)); (d) ovalbumin+formaldehyde (3.0 mg/m(3)); (e) ovalbumin+formaldehyde (3.0 mg/m(3))+HC-030031 (transient receptor potential ankyrin 1 antagonist); (f) ovalbumin+formaldehyde (3.0 mg/m(3))+ capsazepine (transient receptor potential vanilloid 1 antagonist). Experiments were conducted after 4 weeks of combined exposure and 1-week challenge with aerosolized ovalbumin. Airway hyper-responsiveness, pulmonary tissue damage, eosinophil infiltration, and increased levels of interleukin-4, interleukin-6, interleukin-1ß, immunoglobulin E, substance P and calcitonin gene-related peptide in lung tissues were found in the ovalbumin+formaldehyde (3.0 mg/m(3)) group compared with the values seen in ovalbumin -only immunized mice. Except for interleukin-1ß levels, other changes in the levels of biomarker could be inhibited by HC-030031 and capsazepine. CONCLUSIONS/SIGNIFICANCE: Formaldehyde might be a key risk factor for the rise in asthma cases. Transient receptor potential ion channels and neuropeptides have important roles in formaldehyde promoted-asthma.

Application of baculovirus as a delivery vehicle for study of transcription and translation mechanism of parvovirus in non-permissive mammalian cells.

Human bocavirus (HBoV) is a parvovirus associated with respiratory and gastrointestinal diseases in humans. Recombinant baculoviruses have been used widely for many years to transduce transiently and stably a variety of mammalian cell types at high frequencies. In this study, to explore further the use of baculovirus as a gene delivery vehicle for study of transcription and translation mechanism of human bocavirus which lacks susceptible cell culture system, two recombinant baculoviruses were constructed: Bac-BoV-EGFP in which the EGFP gene was under the control of the HBoV1 promoter, and Bac-HBoV1 encompassing the nearly whole HBoV1 genome without both termini. The data demonstrated that efficient gene delivery and expression were observed in numerous mammalian cells transduced by Bac-BoV-EGFP and the transduction rate was much greater than that in plasmid-based transfected cells. The analysis of transcription and translation in Bac-HBoV1 transduced A549 cells showed that two transcripts from NP1 gene were detected by RT-PCR and the NP1 was localized in the nucleus, suggesting that the Bac-HBoV1 recombinant baculovirus delivered efficiently the HBoV1 genome into A549 cells. In summary, this system provides a useful tool for analysis of the transcription and translation of some viruses lacking a virus-cell replication system.

Adjuvant effects of gaseous formaldehyde on the hyper-responsiveness and inflammation in a mouse asthma model immunized by ovalbumin.

Asthma is a complex pulmonary inflammatory disease, which is characterized by airway hyper-responsiveness, airflow obstruction, and airway inflammation. Exposure to a number of chemicals including formaldehyde (FA) can lead to asthma. This study aimed to explore the underlying role of FA exposure in occupational asthma, especially when it is combined with allergen exposure. Balb/c mice were randomly divided into six groups (n = 6/group): (1) saline control; (2) ovalbumin (OVA)-immunized (OVA(imm)) only; (3) 0.5 mg FA/m(3) exposure; (4) OVA(imm) + 0.5 mg FA/m(3); (5) 3.0 mg FA/m(3) FA exposure; and, (6) OVA(imm) + 3.0 mg FA/m(3). These low and high exposure FA levels were adopted from current (0.5 mg/m(3)) and original (3.0 mg/m(3)) Chinese Occupational Threshold Limit Values. Experiments were conducted after 3 week of combined exposure and a 1-week challenge with aerosolized OVA. Airway hyper-responsiveness, pulmonary tissue damage, eosinophil infiltration, and increased interleukin (IL)-4 and IL-6 levels in lung tissues were found in the OVA + 3.0 mg FA/m(3) hosts as compared to values seen in the OVA-immunized only mice. The results here suggest to us that FA exposure can induce and aggravate asthma in Balb/c mice when it is combined with OVA immunization.

Adverse effect of nano-silicon dioxide on lung function of rats with or without ovalbumin immunization.

BACKGROUND: The great advances of nanomaterials have brought out broad important applications, but their possible nanotoxicity and risks have not been fully understood. It is confirmed that exposure of environmental particulate matter (PM), especially ultrafine PM, are responsible for many lung function impairment and exacerbation of pre-existing lung diseases. However, the adverse effect of nanoparticles on allergic asthma is seldom investigated and the mechanism remains undefined. For the first time, this work investigates the relationship between allergic asthma and nanosized silicon dioxide (nano-SiO2). METHODOLOGY/PRINCIPAL FINDINGS: Ovalbumin (OVA)-treated and saline-treated control rats were daily intratracheally administered 0.1 ml of 0, 40 and 80 µg/ml nano-SiO2 solutions, respectively for 30 days. Increased nano-SiO2 exposure results in adverse changes on inspiratory and expiratory resistance (Ri and Re), but shows insignificant effect on rat lung dynamic compliance (Cldyn). Lung histological observation reveals obvious airway remodeling in 80 µg/ml nano-SiO2-introduced saline and OVA groups, but the latter is worse. Additionally, increased nano-SiO2 exposure also leads to more severe inflammation. With increasing nano-SiO2 exposure, IL-4 in lung homogenate increases and IFN-γ shows a reverse but insignificant change. Moreover, at a same nano-SiO2 exposure concentration, OVA-treated rats exhibit higher (significant) IL-4 and lower (not significant) IFN-γ compared with the saline-treated rats. The percentages of eosinophil display an unexpected result, in which higher exposure results lower eosinophil percentages. CONCLUSIONS/SIGNIFICANCE: This was a preliminary study which for the first time involved the effect of nano-SiO2 to OVA induced rat asthma model. The results suggested that intratracheal administration of nano-SiO2 could lead to the airway hyperresponsiveness (AHR) and the airway remolding with or without OVA immunization. This occurrence may be due to the Th1/Th2 cytokine imbalance accelerated by the nano-SiO2 through increasing the tissue IL-4 production.

Mechanism for alpha-MnO2 nanowire-induced cytotoxicity in Hela cells.

Alpha-Manganese dioxide (alpha-MnO2) nanowires are used as electrode materials to significantly enhance the performance of lithium batteries. In this study, we investigate the nanotoxicity of alpha-MnO2 nanowires toward Hela cells. The alpha-MnO2 nanowires, which were successfully synthesized using the hydrothermal approach, can induce cytotoxicity dose-dependently in Hela cells. The accumulation of reactive oxygen species (ROS) and depletion of glutathione (GSH) are also observed in the nanowire-treated cells. In addition, comet assays and cell nucleus morphology show that both DNA damage and cell apoptosis occur in the nanowires exposure group. Based on these results, a mechanism for alpha-MnO2 nanowire-induced cytotoxicity in Hela cells, which involves the accumulation of ROS, formation of oxidative stress, DNA oxidative damage and cell apoptosis, is proposed. This investigation may provide a fundamental insight to understand the nanotoxicity of wire-shaped nanomaterials.