Validated LC-MS/MS method for simultaneous determination of SIM and its acid form in human plasma and cell lysate: Pharmacokinetic application

Simvastatin （SIM） is a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor widely used in hyperlipidemia therapy. SIM has recently been studied for its anticancer activity at doses higher than those used for the hyperlipidemia therapy. This prompted us to study the pharmacokinetics of high-dose SIM in cancer patients. For this purpose, an LC-MS/MS method was developed to measure SIM and its acid form （SIMA） in plasma and peripheral blood mononuclear cells （PBMCs） obtained from patients. Chromatographic analyte separation was carried out on a reverse-phase column using 75：25 （% v/v） acetonitrile：ammonium acetate （0.1 M, pH 5.0） mobile phase. Detection was performed on a triple quadrupole mass spectrometer, equipped with a turbo ion spray source and operated in positive ionization mode. The assay was linear over a range 2.5-500 ng/mL for SIM and 5-500 ng/mL for SIMA in plasma and 2.5-250 ng/mL for SIM and 5-250 ng/mL for SIMA in cell lysate. Recovery was 〉 58% for SIM and 〉 75% for SIMA in both plasma and cell lysate. SIM and SIMA were stable in plasma, cell lysate and the reconstitution solution. This method was successfully applied for the determination of SIM and SIMA in plasma and PBMCs samples collected in the pharmacokinetic study of high-dose SIM in cancer patients.

Immunotherapeutic effects of dendiritic cells vaccine pulsed with tumor cell lysate in mice with pancreatic carcinoma

Objective To observe the immunotherapeutic effects of dendritic cells vaccine pulsed with tumor cell lystate on mice with pancreatic carcinoma. Methods Dendritic cells (MTSC4) were pulsed with tumor cells lysate. The immune preventative and immnotherapeutic effects of DC vaccines on mice with pancreatic carcinoma were assessed. Results After vaccination of the DC vaccines,mice remained tumor-free for at least 25 days in DCs vaccines group,but in other groups the subcutaneous implantation tumorigenesis were found beginning 3 to 9 days. CTL stimulated by DC vaccines effected cytolytic activity against pancreatic carcinoma cells. The survival period was obviously prolonged in DCs vaccines group (56 ±9)d than in other groups P【0.01) and tumors (1.4 ±0.8)g in DCs vaccines group were significantly smaller than that in other groups (P 【 0. 05). Conclusion Tumor cell lysate-pulsed dendrtic cells vaccines can induce a specific and effective immune response against pancreatic carcinoma cell implanted in mice.

Cell lysates and egg white create homeostatic microenvironment for gene expression in cell-free system

Homeostasis widely exists in living systems,and plays essential roles for maintaining normal physiological activities,enabling to preserve their functionalities against variations.Gene expression is a crucial process that allows cells to produce the necessary protein,giving cells the flexibility to adapt to variations.Herein we study homeostasis of gene expression in cell-free system.Heat-inactivated cell lysates and egg white are utilized to create homeostatic microenvironment.Results show that both in cell lysates and egg white,gene expression is maintained at relatively stable levels upon variations including gene amount,magnesium ions and temperature.Our work presents a nascent concept and experimental evidence for the homeostasis in cell-free systems,and provides implication for living systems.

Alcohol dehydrogenase coexisted solid-state electrochemiluminescence biosensor for detection of p53 gene

An alcohol dehydrogenase （ADH）-coexisted solidstate electrochemiluminescence （ECL） biosensor for sensitive detection of the p53 gene was developed. The electrode modified by multiwalled carbon nanotubes, Ru（bpy）]2＋3 and polypyrrole （ MWNTs-Ru （bpy） ]2＋3 -PPy ） was prepared to adsorb the ssDNA by electrostatic interactions. Then, the ssDNA recognized the gold nanoparticles （AuNPs）-labeled p53 gene and produced the AuNPs-dsDNA electrode with the AuNPs layer. The AuNPs layer adsorbed the ADH molecules for producing the ECL signal. Thus, the biosensor was based on coupling enzyme substrate reaction with solid-state ECL detection, and it displayed good sensitivity and specificity. The detection limit of the wild type p53 sequence （wtp53） is as low as 0. 1 pmol/L and the discrimination is up to 57. 1% between the wtp53 and the muted type p53 sequence （mtp53）. The amenability of this method to the analyses of p53 from normal and cancer cell lysates is demonstrated. The signal of wtp53 in the MGC-803 gastric cancer cell lysates turns out to be about 61.8% that of the wtp53 in the GES-1 normal gastric mucosal cell lysates, and the concentration of the wtp53 is found to decrease about 59 times. The method is highly complementary to enzyme-linked immunosorbent assay （ELISA）, and it holds promise for the diagnosis and management of cancer.

The adsorption of cellular proteins affects the uptake and cellular distribution of gold nanoparticles

Nanotechnology has been widely used in the field of medicine, and it can significantly improve the bioavailability and the target efficiency of medicines. However, after administration, nanomedicines can adsorb biomolecules that can influence their effects. It was reported that the adsorption of plasma proteins can change the surface properties of nanoparticles. When nanoparticles pass through cells, they may carry some cellular proteins out of cells. Currently, it is unclear whether the adsorbed proteins affect the uptake of nanoparticles in the next cell layer. To simplify this complex biological process, BSA-capped gold nanoparticles were prepared and incubated with Caco-2 cell lysate to simulate conditions of transcytosis through epithelial cells. The surface morphology of nanoparticles was examined by TEM. SRB was used to evaluate the cytotoxicity of the nanoparticles. The uptake and cellular distribution of the nanoparticles were detected by ICP-MS and CLSM. The results suggested that the adsorption of cell proteins could enhance the adhesion and uptake of gold nanoparticles. The gold nanoparticles were mainly located in lysosomes, and there were some Lysate-capped AuNPs in the mitochondria whereas no BSA-capped AuNPs appeared there.