[Studies on chemical compounds of Chlorella sorokiniana].

Chemical constituents of Chlorella sorokiniana were isolated and purified by repeated column chromatographies, over silicagel and Sephadex LH-20. Their structures were identified on the basis of physicochemical properties and spectroscopic data analysis. Five compounds were obtained from the petroleum ether extract of Chlorella sorokiniana, and their structures were identified as (22E, 24R)-5alpha, 3beta-epidioxiergosta-6, 22-dien-3beta-ol(1),(24S)-ergosta-7-en-3beta-ol(2), loliolide(3), stigmasta-7,22-dien-3beta,5alpha,6alpha-triol(4), and 3beta-hydroxy-5alpha,6alpha-epoxy-7-megastigmen-9-one(5). The main liposoluble fractions from Chlorella sorokiniana maiuly contain fatty acids, alkyl acids and olefine acids. Components 1-5 were isolated from the genus Chlorella for the first time.

Novel dibenzo[b,e]oxepinones from the freshwater-derived fungus Chaetomium sp. YMF 1.02105.

Six new dibenzo[b,e]oxepinone metabolites, chaetones A-F (1-6), as well as three known compounds, 1-hydroxy-6-methyl-8-hydroxymethylxanthone (7), citreorosein (8), and emodin (9), were obtained from a freshwater-derived fungal strain Chaetomium sp. YMF 1.02105. Their structures were established on the basis of extensive spectroscopic data analysis and comparison with spectroscopic data reported. Compounds 1-6 are further additions to the small group of dibenzo[b,e]oxepinones represented by arugosins A-H. Compounds 1-7 were tested for their cytotoxic activities against A549, Raji, HepG2, MCF-7, and HL-60 cell lines. The results showed that compound 3 had significant cytotoxicity with IC50 values of 1.2, 1.8, 1.9, 2.3, and 1.6 µg/mL, respectively, against the five cancer cell lines. All compounds showed modest antimicrobial activity against Staphylococcus aureus (ATCC 6538) in standard disk assays.

Arsenic trioxide up-regulates Fas expression in human osteosarcoma cells.

BACKGROUND: Osteosarcoma is a common primary malignant tumor of bone with a poor prognosis due to its propensity for metastasis. The prognosis of patients is highly dependent on the presence or absence of lung metastasis and on the effectiveness of treatment against it. It has been reported that low level expression of Fas protein in human osteosarcoma cell is closely associated with lung metastasis. A large number of studies have shown that arsenic trioxide (ATO) can inhibit proliferation and induce apoptosis of many cancer cell lines; however, its effects on human osteosarcoma cells (Saos-2 cell line) remains unknown. The aim of this study was to investigate the effects of ATO on Saos-2 cells and to characterize its mechanism of Fas-expressing. METHODS: A group of Saos-2 cells was treated with or without 0.5, 1, 2, 4 and 8 micromol/L ATO for three successive days, and the cytotoxicity of ATO was determined by an 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological changes in cells were studied by acridine orange/ethidium bromide (AO/EB) double staining. Flow cytometry (FCM) was used to assay cell DNA distribution. Another group of cells was pretreated with 10 nmol/L matrix metalloproteinase 7 (MMP-7) for 3 hours. They were then incubated with or without 2 micromol/L ATO for 24, 48 and 72 hours. Cytotoxicity, Fas protein and mRNA levels were systematically studied using MTT, Western blotting and real-time PCR, respectively. Cell proliferation, cell cycle progression and apoptosis were examined in this study. RESULTS: Proliferation of Saos-2 cells was inhibited by ATO in both a dose- and time-dependent manner. The IC(50) values at 24, 48 and 72 hours were 9.30, 5.54 and 3.49 micromol/L, respectively. The survival rate of Saos-2 cells in the MMP-7 and ATO co-treated group was significantly higher than the ATO group, but it was lower than the control group. ATO induced G(1) phase arrest of the cell cycle and very efficiently stimulated apoptosis in Saos-2 cells, as evidenced by flow cytometric detection of sub-G(1) DNA content and AO/EB staining. Western blotting results indicated that Fas (FasL) protein expression in osteosarcoma cultures markedly increases in a time dependent manner after exposure to ATO. Compared with control, treatment with ATO 2 micromol/L and 4 micromol/L for 48 hours, resulted in increase of Fas gene expression to 28.31% and 56.74%, respectively. Our results indicated that ATO induced-apoptosis of Saos-2 cells may be mediated through the Fas pathway. CONCLUSIONS: ATO suppressed cell proliferation of Saos-2 cell in a dose- and time-dependent manner and increased Fas protein expression. However, Fas-mediated apoptosis was incompletely interrupted by MMP-7, which suggested that other molecular mechanisms may mediate this process.

Preparation, characterization, in vivo and in vitro studies of arsenic trioxide Mg-Fe ferrite magnetic nanoparticles.

AIM: MgFe(2)O(4) magnetic nanoparticle composed of As(2)O(3) (As(2)O(3)-MNPs) were prepared and their in vitro and in vivo characteristics were studied. METHODS: The solvent-displacement method was applied for preparation of the nanoparticle using Poly-D,L-lactic-co-glycolic acid(PLGA). The characteristics studies of the products included magnetic response, morphology (transmission electron microscopy and scanning electron microscopy), entrapment efficiency, drug loading, particle sizes, zeta potential, in vitro drug release and tissue magnetic targeting. Nanoparticle cytotoxicity to Saos-2 cells was investigated using the MTT assay. To guide the external magnetic field in the liver, the concentration of As(2)O(3) in the liver and kidney was measured using an atomic fluorescence spectrometer after injecting As(2)O(3)-MNPs into the caudal veins of mice. RESULTS: The As(2)O(3)-MNPs were approximately spherical. The average diameter, drug loading, entrapment efficiency and zeta potential of As(2)O(3)-MNPs were 109.9 nm, 10.08%, 82.16%, and -14.33 mV, respectively. The specific saturation magnetism was 8.65 emu/g. In vivo, the concentration of As(2)O(3) in the liver was significantly higher than that in the non-magnetic group. While the concentration of As(2)O(3) in the kidney was lower than that in the non-magnetic group. The C(max) in liver tissue in the magnetic group was 30.65 microg/g, which was 4.17 times the drug concentration in the same group in kidney tissue (7.35 microg/g) and 2.88 times the concentration of drug (10.66 microg/g) in the liver tissue of the non-magnetic group. CONCLUSION: The PLGA polymer-loaded magnetic nanoparticle composed of arsenic trioxide can be magnetically targeted well and applied in biomedicine.

[Estimation of carbon emission from forest fires in Zhejiang Province of China in 1991-2006].

Forest fire is an important disturbance factor of natural ecosystem, which can release great amount of greenhouse gases. With the persistent global warming, forest fire tends to happen more frequently. Based on the statistical data of forest fires and the biomass data of dominant forest types in Zhejiang Province in 1991-2006, the annual greenhouse gases emission from forest fires in the Province was estimated by using emission factors and emission ratio. The results showed that the annual emissions of CO2, CO, CH4, and non-methane hydrocarbon (NMHC) from forest fires were 127930, 7672.8, 3098.7, and 1475.5 t, and the amounts of annually consumed biomass and carbon were 86148.1 and 38776.7 t, respectively, suggesting that forest fire had definite effects on the regional carbon budget.

[Study on the effect of bone-cement interface with bone cement oscillator].

OBJECTIVE: To evaluate the effect on increasing bone cement-bone interface micro-gomphosis intensity with bone cement oscillator. METHODS: One hundred femoral bones of adult pig were randomly divided into 6 groups: oscillating group (A1) and control group (A2) of anti-tensile force, oscillating group (B1) and control group (B2) of anti-pressure (n = 20 in each group), oscillating group (C1) and control group (C2) of imaging (n = 10 in each group). Mechanics and CT test was performed, micro-gomphosis intensity of bone cement-bone interface between oscillating group and control group was compared. RESULTS: Mechanics and CT test showed bone cement-bone interface micro-gomphosis intensity in oscillating group was significantly stronger than control group (P < 0.01). CONCLUSION: Bone cement oscillator can significantly increase micro-gomphosis intensity of bone-cement interface, and reduce long-term aseptic loosening of artificial prostheses.