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A levonorgestrel-releasing IUD and the Copper T 380Ag IUD were in randomized comparison for seven years in five clinics. In two other clinics the randomized study was truncated at five years, but use of the Copper T continued. No pregnancies occurred to users of either device in years 6 and 7. Cumulative pregnancy rates were 1.1 per 100 at seven years for the steroid-releasing and 1.4 per 100 for the copper-releasing IUDs. Cumulative rates of PID did not differ between devices. Infection rates appeared to be lowest during the sixth and seventh years of the study. Termination attributable to amenorrhea was the principal contributor to differences in cumulative continuation rates between devices. At the five clinics that carried the comparative study to seven years, cumulative continuation rates were 24.9 per 100 for LNg20 IUD users and 29.4 per 100 for TCu 380Ag users. Women who used either method for periods of five to seven years experienced, on average, marked to mild increases in hemoglobin as compared with levels at admission. The Copper T380 family and the LNg20 IUDs represent the most effective reversible contraceptive methods yet studied in long-term randomized trials.

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For studies of the behavioral and physiological effects of nicotine in smokers, delivery ofnicotine via cigarette smoking is highly variable and difficult to control. A more precise method of delivery is needed in order to accurately manipulate the amount of nicotine being presented and, thus, to determine its quantitative effects. The objective of the study reported here was to test an aerosol nasal-spray method of delivering measured doses of nicotine. Eleven healthy males were presented 0 mg (placebo), 0.5 mg, 1.0 mg, and 2.0 mg of nicotine over 5 min during four separate sessions, and changes were observed in plasma nicotine concentration and cardiovascular activity. Dose-response relationships were observed between nicotine presented via this method and plasma nicotine, heart rate, systolic blood pressure, and, to a lesser extent, diastolic blood pressure. These results suggest that this aerosol spray method of presenting nicotine provides the measured doses necessary for quantification of nicotine's effects.

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Summary The prophylactic effect of low doses of subcutaneous heparin in the prevention of deep vein thrombosis after major gynaecological surgery was investigated in a clinical trial involving 110 patients. Evidence of thrombosis was detected by the 1251‐labelled fibrinogen test in 16 out of 55 patients (29 per cent) in the control group, and in 2 out of 55 patients (3.6 per cent) in the heparin‐treated group. Only longevity had a significant association with the development of deep vein thrombosis.

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