[Lactate dehydrogenase isozymes in the corneal epithelium].
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Animals↗
Biomedical subjects
K Shiba
Publications and source records attributed to K Shiba.
Transcutaneous optical telemetry system with infrared laser diode.
A transcutaneous telemetry system is indispensable when monitoring and controlling the operation of an artificial heart totally implanted inside the body. A telemetry system using light is more useful than radio waves from the viewpoint of electromagnetic interference and power consumption. In this report, a transcutaneous optical coupler consisting of an infrared laser diode (LD) and a PIN photodiode (PINPD) was evaluated, and the transcutaneous optical coupling and information transmission characteristics were evaluated in in vitro experiments. The wavelength and directional angle of the LD used were 830 nm and 9.5 degrees, respectively. With regard to the directional angle of PINPD, the authors found that a PINPD with a larger directional angle allowed for more deviation between the axes optical axes of the LD and the PINPD. It was also found that the transcutaneous coupler had an optimum distance for the permissible deviation to be maximized. The information signals modulated by the phase shift keying (PSK) were transmitted at a rate of 9,600 bps through goat skin 4 mm thick, and demodulated by the phase locked loop (PLL) on the receiving side. As a result, the information signals were demodulated without any errors in deviation within 10.5 mm at a distance of 11 mm. In conclusion, the transcutaneous optical telemetry system using an infrared LD has sufficient characteristics to monitor and control the operation of an artificial heart totally implanted inside the body.
Heart, Artificial↗
Selection of a rechargeable internal back-up battery for a totally implantable artificial heart.
Three kinds of rechargeable batteries, NiCd, NiMH, and Li+, were compared for the purpose of selecting the most appropriate battery for use in a Rechargeable Internal Back-up Battery (RIBB) unit for a Totally Implantable Artificial Heart. Batteries of each kind were connected in series to obtain the required driving voltage of 24 V. The NiCd and NiMH batteries were charged by a constant current of 1 C, and the Li+ batteries were charged first by a constant current of 1 C and later by a constant voltage of 28.7 V. All three types of batteries were discharged using a dummy electronic pulsatile load consuming 20 W of power. The tests showed that the Li+ batteries were capable of supplying the required energy for more than 60 minutes. The Li+ batteries had a specific energy of 121.5 Wh/kg, which was more than 3x that of the NiCd and NiMH, and an energy density of 282.5 Wh/L more than double that of the other two. In addition, the Li+ batteries recorded the least temperature rise during charging and discharging. The results of our tests conclusively showed that the Li+ battery is the best among the three for use in an RIBB from the viewpoint of energy density and temperature rise.
Electricity↗
A transcutaneous energy transmission system with rechargeable internal back-up battery for a totally implantable total artificial heart.
We have been developing an externally coupled transcutaneous energy transmission system (ECTETS) for a totally implantable total artificial heart (TITAH). When the ECTETS is unable to supply the energy to drive the TITAH from outside the body, a rechargeable internal back-up battery (RIBB) implanted inside the body is used as a back-up to supply the required energy. This paper reports on the performance characteristics of our ECTETS with an RIBB. In this study, a lithium-ion (Li+) secondary battery was used as the RIBB. The transcutaneous energy transmission and the charging control characteristics of the ECTETS, while simultaneously supplying energy to the TITAH and the RIBB, were evaluated in an in vitro experiment. The output power and transmission efficiency of the ECTETS operating in this mode were found to vary from 20 W to 34 W and from 84% to 71%, respectively. It was also found that a sufficient power of more than 20 W could be supplied to the TITAH. The time needed to fully charge the RIBB was 117 minutes, and a fully charged RIBB could drive the TITAH, consuming 20 W for 62 minutes. It may, therefore, reasonably be concluded that the ECTETS with the RIBB is sufficient to drive the TITAH.
Animals↗
Safety and pharmacokinetics of single oral and intravenous doses of fluconazole in healthy subjects.
At intervals of two to four weeks, eight subjects received 25 mg of fluconazole orally; 50 mg orally; 25 mg intravenously; 50 mg intravenously; and then 100 mg orally (six subjects). Physical examinations and laboratory tests performed before and after each drug administration revealed no side effects or significant changes in test results. After oral administration, plasma fluconazole levels rose rapidly in a dose-dependent manner, maximum levels being reached in 0.7 hours after 25 mg, in 1.4 hours after 50 mg, and in 1.7 hours after 100 mg. After intravenous administration, mean plasma drug levels were higher than after oral administration for 30 minutes and then declined rapidly; at one hour after injection, plasma levels were similar to those seen after oral administration. During 120 hours after oral administration, 69% of the 25-mg dose, 66% of the 50-mg dose, and 75% of the 100-mg dose were recovered unchanged in urine; after intravenous injection, 74% of the 25-mg dose and 72% of the 50-mg dose were recovered. The half-life of fluconazole was 31 to 37 hours after oral and intravenous administration. Calculations of the areas under the plasma fluconazole time curves showed a clear dose-dependent response. The results indicate that fluconazole is a safe and effective antifungal agent.
Administration, Oral↗