The level of proviral DNA in peripheral blood mononuclear cells from a representative group of asymptomatic HTLV-I carriers in Miyazaki district, an HTLV-I endemic area in Japan, was determined by a single-cycle polymerase chain reaction method (PCR). Of 217 subjects, 26% had a high level of proviral DNA, 43% a medium level, 18% a low level, and 13% an undetectable level. In the high-DNA group, 60% had at least 0.6% abnormal lymphocytes on peripheral blood smears, significantly higher than in those with low DNA levels (19%). This association was present for men of all ages and for women under 55. Men were more than twice as likely to have abnormal lymphocytes as well as high levels of proviral DNA. These differences may reflect different host responses to the virus by sex or by the time or route of infection. This study supports the utility of PCR for molecular screening in epidemiologic studies of the natural history of HTLV-I, and may lead to the identification of those carriers who are at greatest risk of developing HTLV-I-induced malignancy.

Isomagnetic maps of 50 normal subjects (control group) and 23 patients with old inferior myocardial infarction (IMI group) were recorded in order to analyse T wave abnormalities in inferior myocardial infarction. The T wave of the magnetocardiogram (MCG) in the control group showed negative deflections in the left upper portion and positive deflections in the right lower portion, thus resulting in a T vector directed leftward and inferiorly. The T wave of the IMI group was flat or positive in the left upper portion and flat or negative in the right lower portion, suggesting a T vector directed superiorly. In addition, opposing dipoles were observed in 36.4% of the IMI group; i.e. one directed superiorly, presumably due to inferior myocardial ischaemia, and the other directed inferiorly due to normal repolarization. Localized T vector abnormalities could be detected by the MCG in some cases, in which coronary T waves of the standard electrocardiogram had returned to normal. Furthermore, multiple dipoles were more frequently observed in the isomagnetic map than in the isopotential map (5 vs. 15; P less than 0.01). These results suggest that the MCG is helpful in diagnosing myocardial ischaemia when this is not detectable on the electrocardiogram.

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