Magnetic measurement is a typical inverse problem in Biomedical field. In this kind of problem we always need to locate the positions and moments of one or more magnetic dipoles. Although using the traditional methods...Magnetic measurement is a typical inverse problem in Biomedical field. In this kind of problem we always need to locate the positions and moments of one or more magnetic dipoles. Although using the traditional methods to solve this kind of inverse problem has all kinds of shortcomings, BPNN (Back Propagation Neural Networks) method can be used to solve this typical inverse problem fast enough for real time measurement. In the traditional BPNN method, gradient descent search method is performed for error propagation. In this paper the authors propose a new algorithm that Newton method is performed for error propagation. For the cost function is highly nonconvex in the magnetic measurement problem, the new kind of BPNN can get convergent results quickly and precisely. A simulation result for this method is also presented.展开更多
AIM To develop a MRI-based method for accurate determination of liver volume(LV) and to explore the effect of long-term everolimus(EVR) treatment on LV in PCK rats with hepatomegaly. METHODS Thirty-one female PCK rats...AIM To develop a MRI-based method for accurate determination of liver volume(LV) and to explore the effect of long-term everolimus(EVR) treatment on LV in PCK rats with hepatomegaly. METHODS Thirty-one female PCK rats(model for polycystic-liverdisease: PCLD) were randomized into 3 groups and treatment was started at 16 wk, at the moment of extensive hepatomegaly(comparable to what is done in the human disease). Animals received: controls(n = 14), lanreotide(LAN: 3 mg/kg per 2 wk)(n = 10) or everolimus(EVR: 1 mg/kg per day)(n = 7). LV was measured at week 16, 24, 28. At week 28, all rats were sacrificed and liver tissue was harvested. Fibrosis was evaluated using quantitative image analysis. In addition, gene(quantitative RT-PCR) and protein expression(by Western blot) of the PI3K/Ak T/m TOR signaling pathway was investigated. RESULTS LV determination by MRI correlated excellent with the ex vivo measurements(r = 0.99, P < 0.001). The relative changes in LV at the end of treatment were:(controls) +31.8%;(LAN) +5.1% and(EVR) +8.8%, indicating a significantly halt of LV progression compared with controls(respectively, P = 0.01 and P = 0.04). Furthermore, EVR significantly reduced the amount of liver fibrosis(P = 0.004) thus might also prevent the development of portal hypertension. There was no difference in phosphorylation of Akt(Threonine 308) between LAN-treated PCK rats control PCK rats, whereas S6 was significantly more phosphorylated in the LAN group. Phosphorylation of Akt was not different between controls and EVR treated rats, however, for S6 there was significantly less phosphorylation in the EVR treated rats. Thus, both drugs interact with the PI3K/Ak T/m TOR signaling cascade but acting at different molecular levels.CONCLUSION Everolimus halts cyst growth comparable to lanreotide and reduces the development of fibrosis. m TORinhibition should be further explored in PCLD patients especially those that need immunosuppression.展开更多
文摘Magnetic measurement is a typical inverse problem in Biomedical field. In this kind of problem we always need to locate the positions and moments of one or more magnetic dipoles. Although using the traditional methods to solve this kind of inverse problem has all kinds of shortcomings, BPNN (Back Propagation Neural Networks) method can be used to solve this typical inverse problem fast enough for real time measurement. In the traditional BPNN method, gradient descent search method is performed for error propagation. In this paper the authors propose a new algorithm that Newton method is performed for error propagation. For the cost function is highly nonconvex in the magnetic measurement problem, the new kind of BPNN can get convergent results quickly and precisely. A simulation result for this method is also presented.
文摘AIM To develop a MRI-based method for accurate determination of liver volume(LV) and to explore the effect of long-term everolimus(EVR) treatment on LV in PCK rats with hepatomegaly. METHODS Thirty-one female PCK rats(model for polycystic-liverdisease: PCLD) were randomized into 3 groups and treatment was started at 16 wk, at the moment of extensive hepatomegaly(comparable to what is done in the human disease). Animals received: controls(n = 14), lanreotide(LAN: 3 mg/kg per 2 wk)(n = 10) or everolimus(EVR: 1 mg/kg per day)(n = 7). LV was measured at week 16, 24, 28. At week 28, all rats were sacrificed and liver tissue was harvested. Fibrosis was evaluated using quantitative image analysis. In addition, gene(quantitative RT-PCR) and protein expression(by Western blot) of the PI3K/Ak T/m TOR signaling pathway was investigated. RESULTS LV determination by MRI correlated excellent with the ex vivo measurements(r = 0.99, P < 0.001). The relative changes in LV at the end of treatment were:(controls) +31.8%;(LAN) +5.1% and(EVR) +8.8%, indicating a significantly halt of LV progression compared with controls(respectively, P = 0.01 and P = 0.04). Furthermore, EVR significantly reduced the amount of liver fibrosis(P = 0.004) thus might also prevent the development of portal hypertension. There was no difference in phosphorylation of Akt(Threonine 308) between LAN-treated PCK rats control PCK rats, whereas S6 was significantly more phosphorylated in the LAN group. Phosphorylation of Akt was not different between controls and EVR treated rats, however, for S6 there was significantly less phosphorylation in the EVR treated rats. Thus, both drugs interact with the PI3K/Ak T/m TOR signaling cascade but acting at different molecular levels.CONCLUSION Everolimus halts cyst growth comparable to lanreotide and reduces the development of fibrosis. m TORinhibition should be further explored in PCLD patients especially those that need immunosuppression.
