Objective To observe short-term rapid atrial electrical activation on atrial size and atrial systolic function. Methods Twelve anesthetized mongrel dogs were underwent insertion of a transvenous lead at the right atrial appendage and subjected to 5 hours of rapid right atrial pacing at 450 beat/min. Acoustic quantification(AQ) waveform on biatrial was recorded before and after 5 hours pacing with AQ technique. All measurements were made in sinus rhythm. Results After 5 hours rapid right atrial pacing, end systolic volume(ESV) of both left and right atrial enlarged significantly from ( 5.92 ? 1.51 )ml to ( 7.27 ? 1.86 )ml,from ( 3.13? 0.71 )ml to ( 3.58 ? 0.73 )ml, respectively; but biatrial function decreased markedly,left and right atrial ejection fraction decreased from ( 51.03 ? 9.45 ) to ( 38.23 ? 10.52 ),from ( 36.76 ? 5.36 ) to ( 30.71 ? 7.97 ), respectively. However, left atrial ESV enlarged more than right atrial (by 23 vs 8,P

OBJECTIVE To explore the effects of irbesartan（Irb）combined with 5-fluorouracil（5-FU）on the proliferation and extracellular signal-regulated kinase （ERK）/peroxidase proliferator-activated receptor γ（PPARγ）signaling pathway of Lewis lung cancer cells. METHODS Lewis lung cancer cells from mice were divided into normal control （NC）group，Irb low-dose （LD）group（1×10－3 mmol/L），Irb high-dose （HD）group（1×10－1 mmol/L），5-FU group （10 μmol/L），Irb LD+ 5-FU group （Irb 1×10－3 mmol/L+5-FU 10 μmol/L）and Irb HD+ 5-FU group （Irb 1×10－1 mmol/L+5-FU 10 μmol/L）. MTT method was used to measure the activity of cell proliferation in each group. Plate colony formation experiment was used to determine the number of cell colonies formed in each group ；Western blot method was used to detect the expression levels of proliferating cell nuclear antigen （PCNA），p53，ERK1/2，p-ERK1/2 and PPAR γ protein in each group. RESULTS Compared with the NC group ，the cell proliferation activity ，the number of colonies formed and the protein levels of PCNA ，p-ERK1/2，and PPARγ were significantly reduced in the other five groups ，and the protein level of p 53 was significantly increased （P＜0.05）；the protein expression of ERK1/2 had no significant difference （P＞0.05）. The changes of above indexes in Irb LD+ 5-FU group and Irb HD+ 5-FU group were more significant than Irb LD group ，Irb HD group and 5-FU group （P＜0.05）. CONCLUSIONS Irb combined with 5-FU can inhibit the proliferation of Lewis lung cancer cell ，and the effect is better than that of the two alone. The mechanism may be related to the inhibition of ERK/PPARγ signal pathway.

AIM: To investigate the mechanism of elemene synergistic bortezomib against multiple myeloma based on ROS-NF-κB-p38MAPK signaling pathway. METHODS: CCK-8 assay was used to detect cell activity. Nude mice were randomly divided into control group, bortezomib (BTZ) group, elemene (ELE) group and combination group. Each group was treated with BTZ, ELE and BTZ combined with ELE, respectively. Tunel staining was performed to observe the apoptosis of tumor tissues. The expressions of Caspase-3, Bcl-2, NF-κB and p38 MAPK were detected by Western Blot. Cell cycle, apoptosis and reactive oxygen species (ROS) expression were detected by flow cytometry using human myeloma U266 cells. RESULTS: When 4.0 μmol/L ELE combined with 50 nmol/L BTZ treated U266, the cell activity was significantly reduced compared with that of NC, BTZ and ELE groups (P< 0.05). The tumor volume of nude mice in BTZ group, ELE group and combined group was significantly reduced compared with the control group (P <0.05), and the combined group was the smallest. Tunel staining results showed that the apoptosis level in the control group was lower than that in the BTZ group, ELE group and the combined group (P<0.05), and the combined group had the lowest apoptosis level. Compared with the control group, the expressions of Caspase-3 and p38 MAPK in BTZ group, ELE group and combination group were significantly increased, while the expression of Bcl-2 was significantly decreased. The apoptosis level and expression of ROS in BTZ group, ELE group and the combined group was significantly increased compared with the control group (P<0.05). CONCLUSION: ELE can enhance the role of BTZ in promoting apoptosis of myeloma cells, which may be achieved by regulating ROS/NF-κB/p38 MAPK signaling pathway to enhance the level of apoptosis of tumor cells to achieve anti-tumor effect.