A novel double-chamber series piezoelectric pump has been presented and tested. The pump is a multi-layer circular planar structure, consisting of PMMA (polymethyl methacrylate) pump body, two PZT actuator membranes and three cantilever valves. The PZT actuators are driven at a phase difference of 180 degrees, which is equal to two one-chamber pumps running in series. The output performance depends on the geometrical parameters of the actuator membrane. The prototype pump, fabricated with the PZT membrane 0.18 mm in thickness and 50 mm in diameter of 50 mm, can deliver drug in either direct way (pumping liquid drug) or indirect way (pumping air to extrude liquid drug from a sealed container). The frequency-response characteristic of the two handling methods is of difference. The pump obtains optimum performance at low frequency for liquid as medium, and at high frequency for air as medium. For both the direct delivery and indirect delivery, the maximum flowrate achieved reached up to 220 ml/min and 35 ml/min, respectively; and the maximum backpressure obtained amounted to about 14 KPa and 21 KPa, respectively, at the applied voltage of 80 V with frequency of 20 Hz.
Drug Delivery Systems ; instrumentation ; Electricity ; Equipment Design ; Evaluation Studies as Topic ; Insulin Infusion Systems ; Models, Theoretical

Objective To study the molecular mechanism of different sensitivities to apoptosis induced by low concentration of As2O3 in PML-RARα negative HL-60 cells and PML-RARα positive NB4 cells. Meth-ods NB4 and HL-60 cells were cultured with As2O3 for 1 to 4 days; cell proliferation were detected by MTT method; the apoptosis was detected by flow cytometry,Bcl-2,Bax and Fas mRNA were determined by RT-PCR. Results The proliferation of NB4 cells was inhibited obviously by As2O3(1.0 μmol/L)with the induction of apoptosis( P <0.05) ,which was accompanied by the down-regulation of Bcl-2 mRNA expression( P <0.05)and the ratio of Bcl-2/Bax(P <0.05), but there was no obvious variation of Bax and Fas expression( P >0.05). Inhibition of proliferation and apoptosis were not obvious in PML-RARα negative HL-60 cells induced by low concentration As2O3 ( P >0.05), and there was no obvious variation of Bcl-2, Bax, Fas mRNA expres-sion or Bcl/Bax ratio( P >0.05). Conclusion The ratio of Bcl-2/Bax is contributed to the different sensitiv-ities of PML-RARα negative HL-60 cells and positive NB4 cells induced by low concentration of As2O3.

OBJECTIVETo detect the expression of cytokines by acute promyelocytic leukemia (APL) cells before and after exposure to arsenic trioxide.

METHODSDiagnoses were performed according to the FAB cytological classification criteria and cytogenetic criteria. Bone marrow or blood samples from APL patients were collected in heparinized tubes, then primary APL cells were separated by traditional Ficoll-Hypaque density centrifugation and purified after adherence to plastic surfaces. IL-1(beta), IL-6, IL-8, TNF alpha and G-CSF levels in the leukemia cell culture supernatants were detected by ELISA. At the same time, nitro blue tetrazolium (NBT) reduction test was used to detect the differentiation of APL cells.

RESULTSAfter 96 hours exposure to arsenic trioxide, 10 - 6 mol/L in vitro or 10 mg/d in vivo, APL cells showed a significant increase of IL-1(beta) (P < 0.05) and G-CSF (P < 0.05) production, and a significant decrease of IL-6 (P < 0.05) and IL-8 (P < 0.05). However, there was no obvious variation of TNF alpha when compared with APL cells without exposure to arsenic trioxide. On the other hand, the proliferation ratio of APL cells in vitro was statistically correlated to the IL-1(beta) secretion ratio or G-CSF secretion ratio. The cell number ratio in patients with detectable IL-1(beta) or G-CSF was higher than that without detectable IL-1(beta) or G-CSF.

CONCLUSIONIL-1(beta) and G-CSF secretion may play an important role in the proliferation of APL cells after exposure to arsenic trioxide.

Arsenicals ; pharmacology ; Cells, Cultured ; Cytokines ; secretion ; Granulocyte Colony-Stimulating Factor ; secretion ; Humans ; Interleukin-1 ; secretion ; Interleukin-6 ; secretion ; Interleukin-8 ; secretion ; Leukemia, Promyelocytic, Acute ; metabolism ; Oxides ; pharmacology ; Tumor Necrosis Factor-alpha ; secretion