Evaluation of Temperature Increase From Joule Heat in Numerical Tooth Model by Applying 500 kHz Current for Apical Periodontitis Treatment-Effect of Applied Voltage and Tooth Conductivity.

For apical periodontitis treatments, a new method with the insertion of an electrode into the root canal of a tooth and application of a current at 500 kHz to sterilize the area by Joule heat has attracted attention. However, few studies have quantified the temperature increase in the root canal. This study aimed to investigate the basic characteristics of the temperature increase in a simple and standard tooth model when energizing a current at 500 kHz to the numerical tooth model with typical electrical and physical properties. We developed a numerical model of a standard tooth (dentin) and periodontal tissues consisting of an alveolar bone, cortical bone, and gingiva, and physiological saline in a root canal and calculated the temperature increase inside the numerical model by a coupled analysis of current and heat when a voltage was applied across the electrodes. The calculated results for the different applied voltages showed a temperature increase at the apical portion of the root canal, which increased with the applied voltage even for the same total supplied energy. The temperature increase occurred at the apical portion of the root canal as the tooth conductivity decreased. When the tooth conductivity was high, a current passed through the dentin, which led to a decrease in the temperature at the apical portion of the root canal. However, a chemical solution with a higher conductivity in the root canal tended to increase the temperature at the apical portion of the root canal, regardless of the tooth conductivity. More efficient approaches for increasing the spatial and temporal temperature for the tooth model target are needed. © 2021 Bioelectromagnetics Society.

Blue light-emitting diodes induce autophagy in colon cancer cells by Opsin 3.

BACKGROUND: Light emitting-diodes (LED) have various effects on living organisms and recent studies have shown the efficacy of visible light irradiation from LED for anticancer therapies. However, the mechanism of LED's effects on cancer cells remains unclear. The aim of the present study was to investigate the effects of LED on colon cancer cell lines and the role of photoreceptor Opsin 3 (Opn3) on LED irradiation in vitro. METHODS: Human colon cancer cells (HT-29 or HCT-116) were seeded onto laboratory dishes and irradiated with 465-nm LED at 30 mW/cm2 for 30 minutes. Cell Counting Kit-8 was used to measure cell viability, and apoptosis and caspase 3/8 expression were evaluated by AnnexinV/PI and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Autophagy and expression of LC-3 and beclin-1 were also evaluated by autophagy assays, RT-PCR and Western blotting. We further tested Opn3 knockdown by Opn3 siRNA and the Gi/o G-protein inhibitor NF023 in these assays. RESULTS: Viability of HT-29 and HCT-116 cells was lower in 465-nm LED-irradiated cultures than in control cultures. LC-3 and beclin-1 expressions were significantly higher in LED-irradiated cultures, and autophagosomes were detected in irradiated cells. The reductive effect of cancer cell viability following blue LED irradiation was reversed by Opn3 knockdown or NF023 treatment. Furthermore, increased LC-3 and beclin-1 expression that resulted from blue LED irradiation was suppressed by Opn3 knockdown or NF023 treatment. CONCLUSION: Blue LED irradiation suppressed the growth of colon cancer cells and Opn3 may play an important role as a photoreceptor.

Theoretical study of evaluation method for MRI metal artifact.

In dental field, the effect of the Magnetic Resonance Imaging (MRI) artifact generated by the magnetic metal is a significant problem. The MRI metal artifact occurs when using magnetic attachment and the keeper of the ferromagnetic substance remains implanted in the mouth as the MR image is taken. In this study, we theoretically evaluated and analyzed the artifact of MR images caused by the keeper based on the actual principle of MRI by means of simulation. As a result we were able to recognize the changes and distortion in the signal strength of the output image. We found that our results of output images and previously reported results of actual measurement are very similar. MRI artifact caused by dental magnetic metal showed that it can be reported by theoretical simulation.

Influence of lipid emulsion for the hematocrit value measured with continuous hematocrit monitor.

Continuous monitoring of hematocrit with a CRIT-LINE monitor (CLM) is used to prevent excess ultrafiltration during hemodialysis and continuous renal replacement therapy. The presence of substances affecting the scattering and absorption rates of multiple wavelengths of near infrared rays of CLM in the blood may affect the measured values with CLM. We examined the influences of lipid emulsion (LE) on hematocrit and relative blood volume (RBV) which were measured with CLM using an in vitro experimental model with human blood. Additions of 10% or 20% of LE increased the hematocrit measured by LCM and decreased the percent change of RBV in proportion to the dose. One percentage of 20% LE in the plasma increased the expected hematocrit measured with CLM by 2.9%. The decrease of initial hematocrit from 48.1% to 43.4% decreased the expected percent change of RBV from -3.4% to -3.7% with the addition of 1 ml of 20% LE to 100 ml blood. These findings indicate that additions of LE increase hematocrit that is measured with CLM in proportion to the dose of LE. Low levels of initial hematocrit will increase the degree of expected percent change of RBV. Attention should be paid to the influence of LE during monitoring with CLM.