Chen Chunying

Direct quantitative speciation of selenium in selenium-enriched yeast and yeast-based products by X-ray absorption spectroscopy confirmed by HPLC-ICP-MS

Selenium (Se)-enriched yeast has probably been the most widely investigated food supplement and the literature on Se speciation in the Se-enriched yeast is fairly abundant, however, the strategy for Se speciation commonly requires complicated pretreatment procedures such as digestion and stepwise extraction. The present study was carried out to apply X-ray absorption spectroscopy (XAS) for the direct speciation of Se species with minimal pretreatment steps. By comparison of the XAS spectra of Se-enriched yeast samples with that of the standard Se species, organic R–Se–R (represented by selenomethionine) was found to be the main chemical form of Se. Quantitative speciation through principal component analysis (PCA) and least-squares linear combination (LC) fitting the Se-enriched yeast samples found 83%, 85% and 81% of R–Se–R (probably selenomethionine which is known to exist in yeast) for SelenoPrecise® yeast, SelenoPrecise® tablets, and Xiweir® tablets, respectively, which is in agreement with those from HPLC-ICP-MS analysis. More broadly, XAS can also be applied to other Se-enriched products with the merit of minimal pretreatment. However since XAS, specifically XANES, can only identify the chemical type rather than specific molecules, other methods like HPLC-ICP-MS are necessary to give not only the coordination environment of Se but also the identity of the Se species.

Combination of synchrotron radiation X-ray fluorescence with isoelectric focusing for study of metalloprotein distribution in cytosol of hepatocellular carcinoma and surrounding normal tissues

The combined use of synchrotron radiation X-ray fluorescence (SRXRF) and isoelectric focusing (IEF) has been developed that allows comparison of the distribution of metal-containing proteins in cytosol of human hepatocellular carcinoma (HCC) with its surrounding “normal” tissues. Proteins in samples from two individuals were separated with thin layer IEF, and the contents of Fe, Cu and Zn in protein bands were determined with SRXRF after drying the IEF gel. The results show that the metal-containing proteins in these samples of hepatocellular cytosol are specific for a given patient, and the distribution patterns of metal-containing proteins are distinguishable between the HCC and “normal” tissues. The technique has the advantages of quantifying trace elements and identifying proteins simultaneously.

Study of Selenium Speciation in Selenized Rice Using High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometer

On the basis of Osborne fractionation, albumin, globulin, prolamine, and gluletin in selenium (Se) rich rice were extracted with water, 2% NaCl solution, 70% alcohol, and 0.5% alkaline solution subsequently. The content of Se in these protein extracts was determined by inductively coupled plasma mass spectrometry (ICP-MS). The chemical forms of Se in albumin extract and enzymatic digests of rice were analyzed with a hyphenated technique of high performance liquid chromatography and ICP-MS. The Se content in four types of extracts shows an order of gluletin > prolamine > albumin > globulin. The protein with molecular weight of 12.6 kDa is the primary Se-containing protein in extracts of albumin, and the Se from selenocysteme is approximately 30% of the total Se present in the selenized rice.

Subcellular distribution patterns of twenty four elements in the human liver samples studied by molecular activation analysis

Molecular activation analysis based on biological separation techniques combined with instrumental neutron activation analysis (INAA) was applied to study the distribution patterns of 24 elements, including essential and unknown trace elements in the liver organelles. Concentrations of As, Au, Co, I, Mg, Mo, Sb, Sc, Se and Th were found to be the highest in nuclei and mitochondria, while those of Br, Cl, Cs, Cu, K, Na, Rb and V were found to be in cytosol. Concentrations of Al, As, Au, Ba, Fe, I, Sb were found to be the lowest in cytosol. The element As was mainly present in the nuclear fraction, where its concentration was two to four times higher than that in other fractions. Ca and Fe were highly enriched in the microsomal fraction.

Mor-platin a new platinum complex that can induce apoptosis and inhibit migration

Since cisplatin was discovered and applied clinically, people have synthesized thousands of platinum compound derivatives. These platinum derivatives are effective in chemotherapy for some tumors including testicular cancer, ovarian cancer, lung cancer, bladder cancer, head and neck cancer. All of these platinum complex are believed to exert their unparalleled anticancer potency by interacting with nulear DNA, resulting in DNA adducts formation and consequently lead to cell apoptosis, cell cycle arrest and reactive oxygen species released. However, these platinum complex are severely limited by drug resistance and undesirable side effects arising from relatively low specificity and resultant high dosage requirement. To overcome the drug-resistance and improve therapeutic efficiency, it is necessary to synthesized new platinum complex. Our group successfully synthesized a new platinum complex Mor-platin, it can significantly damage more tumor cells than traditional drug cisplatin, while the other biological effects have not been studied. This work aims to study the effect of Mor-platin on its anti-cancer ability, cell migration and cell invasion. In order to detect anti-cancer efficiency, MTT assay was used, and the results showed that IC 50 of Mor-platin (14.41 μ g mL - 1 ) was far less than IC 50 of cisplatin (97.29 μ g mL - 1 ), suggesting that Mor-platin have potentially higher tumor cytotoxicity than cisplatin. Next, we used reactive oxygen species assay kit, western blot analysis, apoptosis and cell cycle kit to assess whether Mor-platin can cause cell death by apoptosis, cell cycle, ROS, apoptosis-related protein and caspase protein. The results showed that Mor-platin can increase level of ROS, arrest cell cyle in S phase, increase ratio of Bax/Bcl-2 and activate caspase 3/8/9 resulting in cleaved PARP, ultimately lead to cell death. The major threat of cancer is not from the primary tumor itself but from metastasis to other organs. To develop successful metastases, cancer cells need to disseminate to a distant organ, migrate out of the primary tumor, invade to blood or lymphatic vessels, finally seed, proliferate and colonize to form secondary tumors. Cell migration is a basic process within the cancer. Tumor metastasis is a major cause of cancer deaths, 90% of the cancer deaths can be attributed to the tumor metastasis, therefore it is necessary to avoid tumor metastasis on clinical cancer treatment. Only understanding the clear tumor metastasis for emerging antitumor drugs, they can be obtained to development and application. Current tumor metastasis experiments include transwell assay, wound-healing assay, microcarrier beads, three-dimensional assay and so on. Here, we used wound-healing assay and transwell assay to quantify the migration inhibitory activity of Mor-platin. Intriguingly, both wound-healing assay and transwell assay showed that Mor-platin can also inhibit cell migration and invasion, while cisplatin did not show any same effects. In summary, this new platinum complex Mor-platin not only have high anti-cancer efficiency but also inhibit migration, providing a novel strategy for the development of next generation platinum complex with optimal anti-tumor activities.

Cellular and molecular mechanisms of pulmonary toxicity caused by car-bon nanotubes with various physiochemical properties

Due to their unique mechanical, electronic and chemical properties, carbon nanotubes (CNTs) have been promising candidates for a wide variety of revolutionary applications in information, photovoltaic, energy, sensors, materials, medicine and so on. Meanwhile, with the increasing large-scale production and application of CNTs, their bio-safety assessment has raised wide attention. Although there is considerable experimental data of CNT pulmonary toxicity at the molecular, cellular and whole animal levels, many conclusions are inconsistent and in some cases directly conflicting. The conflicting reports can be attributed to real sample-to-sample variation in material properties, such as types and contents of metal impurities, dispersity, aspect ratio, etc.. In this review, we describe recent research progress on respiratory toxicity of CNTs and its cellular mechanisms, which may depend on the structure and properties of CNTs. Furthermore, many factors that may affect cytotoxicity of CNTs are summarized and discussed here. Finally, we provide a prospect to the future work on studying and evaluating pulmonary toxicity of the CNTs systematically and scientifically.