[Experimental study of percutaneous hot ethanol injection therapy (PHEIT) by continuous heating device for hepatocellular carcinoma].

Percutaneous ethanol injection therapy (PEIT) is widely used as a local treatment for hepatocellular carcinoma (HCC). However, because only a small amount of ethanol can be used in one PEIT session and because the antitumor effect is limited, this modality is indicated only when there are three or fewer tumors and when the tumor diameter is < or = 3 cm. To obtain a more potent and certain antitumor effect, we have devised a new treatment called percutaneous hot ethanol injection therapy (PHEIT), and developed a Continuous Heating Device with which ethanol can be heated and locally injected at a specified temperature. The continuous Heating Device is composed of three major components: a syringe heater, a needle thermocontroller, and a needle tip thermosensor. A disposable syringe filled with liquid is inserted into the syringe heater, which heats the liquid to a desired temperature by adjusting the voltage. The needle thermocontroller is a puncture guide needle to which a heating device has been attached. The needle-tip thermosensor constantly measures, displays and records the temperature of the liquid at the needle tip during injection. Also, because the Continuous Heating Device is a closed-circuit system, there is no risk of accidental a fire, which ensures procedural safety. It is also possible to use this device to safely heat and inject a variety of other liquids, such as physiological saline and anticancer agents and thus contribute to the widespread development of ultrasound-guided injection therapy.

On the oscillatory phenomenon in an oil/water interface.

A simple theoretical model is presented for simulating the self-sustained oscillations of electric potential and pH at an oil/water interface appearing in a two-phase system composed of 2-nitropropane solution containing picrate acid and an aqueous solution of cetyltrimethylammonium bromide. In the present model, a well-known condition necessary for the occurrence of self-sustained oscillations, i.e., the presence of a positive feedback process far from equilibrium, is taken into account in a set of kinetic equations to describe simplified characters of the following two processes: (i) a cooperative formation of ion pair complexes at the interface, and (ii) supply of picrate anions and cetyltrimethylammonium cations to the interface accompanied by release of ion pair complexes to the organic phase. The numerical solutions of the present equations are shown to reproduce fairly well the characteristic properties of the oscillation of electric potential and pH such as wave forms and frequencies.