Volume conduction energy transfer for implantable devices.

A common model of power supply for implantable devices was established to study factors affecting volume conduction energy transfer. Electromagnetic and equivalent circuit models were constructed to study the effect of separation between the source electrode pairs on volume conduction energy transfer. In addition, the parameters of external signal including waveform, amplitude and frequency were analyzed. As the current amplitude did not lead to tissue injury and the current frequency did not cause nerve excitability, the recommended separation between the source electrodes was 3 cm, the proposed waveform of signal source was sinusoidal wave and the optimal frequency was 200 KHz. In agar experiment and swine skin experiment, the current transfer efficiencies were 28.13% and 20.65%, respectively, and the energy transfer efficiencies were 9.86% and 6.90%, respectively. In conclusion, we can achieve optimal efficiency of energy transfer by appropriately setting the separation between the source electrode parameters of the signal source.

[A dynamic observation on serum cytokine and immunoglobulin (IgG, IgA, IgM) in patients with esophageal cancer].

OBJECTIVE: To study the changes of serum interleukin-2 (IL-2), interleukin-8 (IL-8) and immunoglobulin (IgG, IgA, IgM) in patients with esophageal cancer, and to probe the relationship between the levels of IL-2, IL-8, IgG, IgA and IgM and the progress of cancer. METHODS: The serum levels of IL-2 and IL-8 were detected by enzyme-linked immunosorbent assay for 72 case of primary esophageal cancer, 68 advanced esophageal cancer and 120 healthy controls, and the level of immunoglobulin (IgG, IgA, IgM) in patients with esophageal cancer was dynamically observed. RESULTS: The IL-2 level in patients with early esophageal cancer [(1.69 +/- 0.53) ng/ml] or late esophageal cancer [(1.11 +/- 0.60) ng/ml] was lower than the control group [(2.78 +/- 0.51) ng/ml] (P < 0.01), the late esophageal cancer group was lower than early esophageal cancer group (P < 0.05). The level of IL-8 in patients with early esophageal cancer [(85.48 +/- 6.14) ng/L] or late esophageal cancer [(121.41 +/- 6.22) ng/L] was much higher than the control group [(54.48 +/- 12.20) ng/L] (P < 0.01), the late esophageal cancer group was much higher than early esophageal cancer group (P < 0.01); There was correlation between the levels of IL-2 and IL-8 and the worsen-extent of the tumour in patients with early esophageal cancer or late esophageal cancer. But the level of IgG [(12.23 +/- 2.50) g/L], IgM [(1.60 +/- 0.80) g/L] in the patients with esophageal cancer compared with the level of IgG [(11.65 +/- 3.70) g/L], IgM [(1.46 +/- 0.71) g/L] in the health control group have no significant difference (P > 0.05), the level of IgA [(3.50 +/- 1.10) g/L] in patients with esophageal cancer Compared with the control group [(1.88 +/- 1.08) g/L] has significant difference (P < 0.01), and along with the worsen-extent of the tumor in patients the level of IgA has the increased tendency. CONCLUSION: The IL-8 might accelerate the pathogenesis of esophageal cancer, and the IL-2 might restrain. The positive correlation between the level of IgA and the patients with esophageal cancer is observed in this study; the immune maladjustment of IL-2, IL-8 and IgA might be correlative to esophageal cancer, and the IL-2, IL-8 and IgA levels might be an available index for the severity of esophageal cancer, Which may be of some help for clinic practitioners to judge the progress, curative effect and prognosis of the cancer.

[Serum level and genotype of interleukin-6 in patients with esophageal cancer].

OBJECTIVE: To investigate the polymorphism of the interleukin-6 (IL-6) gene promoter-572C/G and -634C/G in patients with esophageal cancer, and to study the relation between the serum level and genotype of interleukin-6 and esophageal cancer. METHODS: Peripheral blood samples were collected from 118 patients with esophageal cancer and 130 healthy persons as controls. The polymorphism of IL-6 was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The serum level of IL-6 was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: The frequency of the genotype GG of the IL-6 (-634) site in the cancer group was 12.7%, significantly higher that that of the control group (3.8%, P<0.05). The risk of esophageal cancer of the G allele carriers was 1.759 times that of the C allele carriers (OR=1.759, 95% CI=1.150-2.691). The serum level of IL-6 of the esophageal cancer group was (16.9+/-5.3) ng/L, significantly higher than that of the control group [(4.6+/-2.6) ng/L, P<0.01]. The serum level of IL-6 of the esophageal cancer with the G allele carriers was (18.8+/-6.1) ng/L, significantly higher than that of the esophageal cancer without the G allele carriers [(13.2+/-6.0) ng/L, P<0.01]. There was no significant difference in the distribution of the IL-6 gene-572C/G polymorphism between the 2 groups (P>0.05). CONCLUSION: IL-6 gene-634C/G polymorphism is associated with the esophageal cancer. The IL-6 allele G carriers may be at increased risk of the esophageal cancer because of the increase of the IL-6 expression.