We have measured non-ortho-substituted (coplanar) polychlorinated biphenyl (PCB) levels as well as polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels in human adipose tissue and serum collected in Atlanta, Georgia. The results show that the concentrations ofthe coplanar PCBs can be more than an order of magnitude higher than the concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin. Our measurements in pooled serum collected in 1962, 1988, and 1969 show a decrease in coplanar PCB levelsfrom 1982 to 1989. Wefound that the pattern ofrelative amounts ofcoplanar PCBs in adipose tissue varied greatly from person to person unlike the PCDD and PCDF patterns, which were more nearly the same. Age was significantly correlated with the concentrations of 2,3,7,3,3'4,3,3',4,4A,5-PCB, and 3,3'4A,45,5'-PCB in adipose tissue. We also measured levels of the mono-and di-ortho chlorinesubstituted PCBs in human serum. The levels for some of these PCB congeners were three orders of magnitude higher than the coplanar PCBs, PCDDs, and PCDFs. We used the international toxicity equivalency factors (TEFs) for PCDDs and PCDFs and the TEFs proposed by Safe for PCBs to calculate the 2,3,7,-TCDD equivalents. Four PCBs (3,3',4,4,5-;

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SUMMARY The administration of verapamil to patients receiving ,B-adrenergic blocking drugs is reported to produce adverse circulatory reactions, but a systematic investigation of this potential drug interaction has not been performed in man. We administered 40-, 80-and 120-mg doses of verapamil orally to 15 patients with angina pectoris who were receiving high doses of propranolol or metoprolol. Verapamil produced dose-dependent decreases in cardiac performance: with 120 mg, cardiac index decreased by 0.38 I/min/m2, stroke volume index decreased by 2.8 ml/beat/m2 and heart rate decreased by 6 beats/min, associated with increases in pulmonary capillary wedge (2.2 mm Hg) and mean right atrial pressures (1.7 mm Hg) (all p < 0.01); two patients had marked, but asymptomatic, hypotensive reactions. In contrast, repeat administration of 120-mg doses of verapamil 24-30 hours after withdrawal of A blockade produced no significant cardiodepressant effects despite significantly higher plasma levels of verapamil than during propranolol therapy (383.1 vs 205.1 ng/ml, p < 0.01). In conclusion, verapamil produces significant negative inotropic and chronotropic effects in patients treated with 3-adrenergic antagonists; combination therapy should therefore be used with caution in patients with angina pectoris.

Three Dutch marine battalions (n=2289) serving in Western Cambodia during 1992-1993 used mefloquine as weekly malaria chemoprophylaxis. One battalion started with a loading dose. Full compliance with prophylaxis was reported by 86.3%, and possible mefloquine-related adverse events were reported by 30.2%. Sixty-four periods of malaria were diagnosed in 59 marines. During deployment, 31 Plasmodium falciparum and no Plasmodium vivax infections occurred. After return, there were 11 cases of falciparum malaria and 22 of vivax malaria, 16-72 days and 30-540 days, respectively, after stopping prophylaxis. Mefloquine-resistant parasites were isolated from 4 Dutch and 4 Khmer patients. Long-term mefloquine prophylaxis was well tolerated but not totally effective.