Dicer, the key enzyme in the RNAi pathway, is misregulated in tumor tissues. The altered expression of Dicer is associated with clinical characteristics in patients with cancer. Liver carcinoma and adjacent non-neoplastic tissues were obtained from 36 patients with hepatocellular carcinoma (HCC) undergoing surgery. Expressions of Dicer mRNA were evaluated using the Real-time reverse transcription-PCR in 36 liver carcinoma tissues and 36 adjacent histologically non-cancerous liver tissues. Dicer mRNA levels were evaluated in relation to age, sex, tumor number, tumor size, tumor stage, and distant metastasis. Dicer mRNA level was significantly lower in malignant tissues than in the corresponding non-neoplastic tissues in 34 of the 36 patients with HCC (94.4%). The Dicer expression level was not associated with clinical characteristics, including age, sex, tumor number, tumor size, tumor stage, or distant metastasis in HCC cases. These results demonstrate that Dicer is significantly down-regulated in HCC, suggesting that reduced expression of Dicer may play an important role during the process of hepatocarcinogenesis.

No abstract

Open-end winding motors are used extensively in ship electric propulsion systems, in which medium-voltage high-power inverters are a critical component. To increase the system voltage and power density, a dual five-level active neutral-point clamped (ANPC) inverter is proposed herein to drive medium-voltage open-end winding motors for ship electric propulsion. Each phase of this inverter comprises two five-level ANPC bridges and all the phases are powered by a common direct-current link. A hybrid modulation method is proposed to control this inverter. The series-connected switches in all the five-level ANPC bridges are operated at the fundamental frequency, and the other switches are controlled with a phase-shifted pulse-width modulation (PWM), which can achieve a natural balance between the neutral-point voltage and flying capacitor voltages in a carrier period. A closed-loop capacitor voltage balancing method based on adjusting the duty ratios of the PWM signals is proposed. The neutral-point voltage and flying capacitor voltages can be controlled independently and balanced without affecting the output phase voltage. Simulation and experimental results are presented to demonstrate the validity of this method.

A minimum safe distance of 5.0 mm between the RFA electrode and intrahepatic bile ducts was effective in preventing serious complications secondary to bile duct injury in a canine model.

It is both safe and feasible to perform RFA near the IVC. The shape and size of the coagulation zone should be considered when electrodes are placed in this area. Near the IVC, the size of the coagulation zone was decreased, and it was incompletely formed.