Aim:  To evaluate the ability of high‐energy ultraviolet A (UVA) light‐emitting diode (LED) to inactivate bacteria in water and investigate the inactivating mechanism of UVA irradiation. Methods and Results:  We developed a new disinfection device equipped with high‐energy UVA‐LED. Inactivation of bacteria was determined by colony‐forming assay. Vibrio parahaemolyticus, enteropathogenic Escherichia coli, Staphylococcus aureus and Escherichia coli DH5α were reduced by greater than 5‐log10 stages within 75 min at 315 J cm−2 of UVA. Salmonella enteritidis was reduced greater than 4‐log10 stages within 160 min at 672 J cm−2 of UVA. The formation of 8‐hydroxy‐2′‐deoxyguanosine in UVA‐LED irradiated bacteria was 2·6‐fold higher than that of UVC‐irradiated bacteria at the same inactivation level. Addition of mannitol, a scavenger of hydroxyl radicals (OH˙), or catalase, an enzyme scavenging hydrogen peroxide (H2O2) to bacterial suspensions significantly suppressed disinfection effect of UVA‐LED. Conclusion:  This disinfection system has enough ability to inactivate bacteria and OH˙ and H2O2 participates in the disinfection mechanism of UVA irradiation. Significance and Impact of the Study:  We newly developed UVA irradiation system and found that UVA alone was able to disinfect the water efficiently. This will become a useful disinfection system.

A new impedance analytical system was developed, and measurements were performed over a frequency range of 0–200 kHz by the three-electrode method. The three electrodes consist of a coaxial needle electrode inserted into the tumor and a large reference electrode on the upper abdominal wall. The electrical bio-impedance was measured in 54 patients with breast tumors. The biological tissue can be regarded electrically as an equivalent consisting of extracellular resistance (Re), intracellular resistance (Ri), and electrical capacitance of the cell membrane (Cm). These three parameters were calculated from the measured values of electrical bio-impedance by the curve-fitting technique using a computer program. It was found that Re and Ri of breast cancers were significantly higher than those of benign tumors (p < 0.01), and that Cm of breast cancers was significantly lower than that of benign tumors (p < 0.01). Measurement of the electrical bio-impedance of breast tumors may have value in the differential diagnosis of breast lesions.

BackgroundLight 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.MethodsHuman 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.ResultsViability 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.ConclusionBlue LED irradiation suppressed the growth of colon cancer cells and Opn3 may play an important role as a photoreceptor.

The flow of blood in the presence of a magnetic field gives rise to induced voltages in the major arteries of the central circulatory system. Under certain simplifying conditions, such as the assumption that the length of major arteries (e.g., the aorta) is infinite and that the vessel walls are not electrically conductive, the distribution of induced voltages and currents within these blood vessels can be calculated with reasonable precision. However, the propagation of magnetically induced voltages and currents from the aorta into neighboring tissue structures such as the sinuatrial node of the heart has not been previously determined by any experimental or theoretical technique. In the analysis presented in this paper, a solution of the complete Navier-Stokes equation was obtained by the finite element technique for blood flow through the ascending and descending aortic vessels in the presence of a uniform static magnetic field. Spatial distributions of the magnetically induced voltage and current were obtained for the aortic vessel and surrounding tissues under the assumption that the wall of the aorta is electrically conductive. Results are presented for the calculated values of magnetically induced voltages and current densities in the aorta and surrounding tissue structures, including the sinuatrial node, and for their field-strength dependence. In addition, an analysis is presented of magnetohydrodynamic interactions that lead to a small reduction of blood volume flow at high field levels above approximately 10 tesla (T). Quantitative results are presented on the offsetting effects of oppositely directed blood flows in the ascending and descending aortic segments, and a quantitative estimate is made of the effects of assuming an infinite vs. a finite length of the aortic vessel in calculating the magnetically induced voltage and current density distribution in tissue.

Ultraviolet (UV) irradiation is an increasingly used method of water disinfection. UV rays can be classified by wavelength into UVA (320-400 nm), UVB (280-320 nm), and UVC (<280 nm). We previously developed UVA sterilization equipment with a UVA light-emitting diode (LED). The aim of this study was to establish a new water disinfection procedure using the combined irradiation of the UVA-LED and another UV wavelength. An oxidative DNA product, 8-hydroxy-2'-deoxyguanosine (8-OHdG), increased after irradiation by UVA-LED alone, and the level of cyclobutane pyrimidine dimers (CPDs) was increased by UVC alone in Vibrio parahaemolyticus. Although sequential irradiation of UVA-LED and UVC-induced additional bactericidal effects, simultaneous irradiation with UVA-LED and UVC-induced bactericidal synergistic effects. The 8-OHdG and CPDs production showed no differences between sequential and simultaneous irradiation. Interestingly, the recovery of CPDs was delayed by simultaneous irradiation. The synergistic effect was absent in SOS response-deficient mutants, such as the recA and lexA strains. Because recA- and lexA-mediated SOS responses have crucial roles in a DNA repair pathway, the synergistic bactericidal effect produced by the simultaneous irradiation could depend on the suppression of the CPDs repair. The simultaneous irradiation of UVA-LED and UVC is a candidate new procedure for effective water disinfection.