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The aim of interferon treatment for chronic hepatitis C is eradication of the hepatitis C virus during the early stages of the disease to prevent progression to liver cirrhosis or hepatocellular carcinoma. However, the effects of interferon on preventing the development of hepatocellular carcinoma for chronic hepatitis C without cirrhosis remain obscure. We wished to study these effects. In this retrospective study, we followed up 66 patients with chronic hepatitis C who were treated with interferon alfa-2a (total dose 324 to 792 MIU) for an average period of 3 years after treatment. Of these 66 patients, 3 patients developed hepatocellular carcinoma during the follow-up period (range, 0.3 to 2.8 years; yearly incidence 1.5%). All 3 patients were among 27 patients who did not respond to interferon treatment. Of these 3 patients, 1 patient developed liver cirrhosis after interferon treatment, and the histologic staging of the remaining 2 patients before interferon treatment was F3, according to the new Inuyama classification. None of the 18 patients who were complete responders to interferon treatment or the 21 patients with incomplete responses developed hepatocellular carcinoma. Our results suggest that patients with chronic hepatitis C who have no response to interferon treatment and histologically advanced disease should be closely followed up after interferon treatment, although the mechanism of malignant transformation to hepatocellular carcinoma in patients with chronic hepatitis C virus infection is still obscure.

An ultra-miniature, general-purpose rubidium gas cell frequency standard with a two-cell scheme has been successfully developed, with the aim of developing one of the smallest atomic frequency standards in the world. The target volume of the new rubidium frequency standard is less than 100 cm/sup 3/. It is assumed that the shape of oscillator enables to mount on a printed circuit board. In order to miniaturize the volume and height, the physics package is made small. Because the frequency of the cavity resonator is 6.834 GHz and the resonator mode is TE/sub 111/, the inside diameter of the cavity needs to be 26 mm. To reduce the inside diameter, a new cavity resonator, which contains a dielectric material, has been developed. As a result, an inside diameter of 16 mm and a capacity of 6.7 cm/sup 3/ are achieved. The total size of the physics package, which contains a rubidium-lamp exciter, a preamplifier, and a single magnetic shield of mumetal, is reduced to 25 cm/sup 3/. By applying the PLL method, instead of the conventional frequency multiplier for a high frequency circuit that generates resonance frequency of 6.834 GHz from a slave oscillator, the size and cost of the circuit are minimized. As for the reduction of the power consumption, a new switching regulator IC is adopted in the power circuit. In addition, with the use of DDS, it enables to set the output frequency within the range of 1 to 15 MHz. Because of these features, the new rubidium frequency standard is extremely small in volume (95 cm/sup 3/), and lightweight (180 grams).