Tao Kaixiong

Preparation and Acute Toxicology of Nano-Magnetic Ferrofluid*

SummaryThe nano-magnetic ferrofluid was prepared by chemical coprecipitation and its acute toxicology was investigated. The effective diameter (Eff. Diam.) of the magnetic particles was about 19.9 nm, and the concentration of the ferrofluid was 17.54 mg/ml. The acute toxic reaction and the main viscera pathological morphology of mice were evaluated after oral, intravenous and intraperitoneal administration of the nano-magnetic ferrofluid of different doses respectively. Half lethal dose (LD50)>2104.8 mg/kg, maximum non-effect dose (ED0)=320.10mg/kg with oral; LD50>438.50 mg/kg, ED0=160.05 mg/kg with intravenous route; and LD50>1578.6 mg/kg, ED0=320.10 mg/kg with intraperitoneal administration. Degeneration and necrosis of viscera were not found. So the nano-magnetic ferrofluid, of which toxicity is very low, may be used as a drug carrier.

Enhancer of zeste homolog 2 depletion induces cellular senescence via histone demethylation along the INK4/ARF locus

Polycomb group proteins are epigenetic transcriptional repressors that function through recognition and modification of histone methylation and chromatin structure. As a member of PcG proteins, enhancer of zeste homolog 2 (EZH2) targets cell cycle regulatory proteins which govern cell cycle progression and cellular senescence. In previous work, we reported that EZH2 depletion functionally induced cellular senescence in human gastric cancer cells with mutant p53. However, whether EZH2 expression contributes to the change of key cell cycle regulators and the mechanism involved are still unclear. To address this issue, we investigated the effects of EZH2 depletion on alteration of histone methylation pattern. In gastric cancer cells, INK4/ARF locus was activated to certain extent in consequence of a decrease of H3K27me3 along it caused by EZH2 silence, which contributed substantially to an increase in the expression of p15(INK4b), p14(ARF) and p16(INK4a) and resulted in cellular senescence ultimately. Furthermore, MKN28 cells, which did not express p16(INK4a) and p21(cip), could be induced to senescence via p15(INK4b) activation and suppression of p15(INK4b) reversed senescence progression induced by EZH2 downregulated. These data unravel a crucial role of EZH2 in the regulation of INK4/ARF expression and senescence procedure in gastric cancer cells, and show that the cellular senescence could just depend on the activation of p15(INK4b)/Rb pathway, suggesting the cell-type and species specificity involved in the mechanisms of senescence inducement.

Laparoscopy Splenectomy for Massive Splenomegaly

ABSTRACT Objective: This study is aimed to evaluate the feasibility of laparoscopic splenectomy (LS) for massive splenomegaly in patients with hypersplenism secondary to portal hypertension and liver cirrhosis. Method: A retrospective study of adult patients was conducted for splenectomy occurring from January 2006 to December 2010. We have performed the surgical procedures of splenectomy in 80 patients who were suffering from splenomegaly or hypersplenism secondary to portal hypertension and liver cirrhosis, among whom 40 patients underwent LS and another 40 patients received open surgery (OS). Results: Among the patients who had undergone LS, 2 patients were converted to OS and the other 38 patients underwent complete LS. The operation time, intraoperative blood loss, and the length of stay in LS group and OS group were 100–200 min (mean: 150 ± 30 min) vs. 120–210 min (mean: 100 ± 30 min), 50–1,000 ml (mean: 150 ± 110 ml) vs. 60–900 ml (mean: 140 ± 50 ml) and 4–9 days (mean: 6.1 ± 2.2 days) vs. 8–14 days (mean: 11.3 ± 2.3 days), respectively. No deaths occurred in the two groups, and there are no significant differences between the two groups in terms of estimated blood loss, complications, length of stay, and operating time. Conclusion: LS for treatment of massive splenomegaly is a feasible, effective, and safe surgical technique. Hypersplenism secondary to portal hypertension and liver cirrhosis are not supposed to be considered absolute contraindications to LS.