| 2. |
- Johannsson, Gudmundur, 1960, et al.
(författare)
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Low dose dehydroepiandrosterone affects behavior in hypopituitary androgen-deficient women: a placebo-controlled trial.
- 2002
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 87:5, s. 2046-52
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-eight women, aged 25-65 yr, with androgen deficiency due to hypopituitarism were treated with oral dehydroepiandrosterone (DHEA; 30 mg/d if <45 yr of age and 20 mg if > or =45 yr of age) for 6 months in a randomized, placebo-controlled, double blind study, followed by a 6-month open treatment period. The administration of DHEA raised the serum levels of DHEAS to normal age-related reference ranges and increased androstenedione and T to subnormal levels. Androgen effects on skin and/or pubic and/or axillary hair were observed in 84% (32 of 38) of the women after all received 6 months of DHEA treatment. No such effects were observed after the placebo treatment. These effects after 6 months were correlated with the serum levels of DHEAS (r = 0.37; P = 0.03), androstenedione (r = 0.42; P = 0.01), and T (r = 0.37; P = 0.03). The percentages of partners who reported improved alertness, stamina, and initiative by their spouses were 70%, 64%, and 55%, respectively, in the DHEA group and 11%, 6%, and 11%, respectively, in the placebo group (P < 0.05). According to the partners, sexual relations tended to improve compared with placebo (P = 0.06). After 6 months of treatment, increased sexual interest or activity was reported by 50% of the women taking 30 mg DHEA, by none taking 20 mg DHEA, and by two women taking placebo (P = NS). Compared with levels after placebo administration, high density lipoprotein cholesterol and apolipoprotein A-1 levels decreased after DHEA. Serum concentrations of IGF-I, serum markers of bone metabolism, and bone density did not change. In conclusion, oral administration of a low dose of DHEA to adult hypopituitary women induced androgen effects on skin and axillary and pubic hair as well as changes in behavior, with only minor effects on metabolism.
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| 3. |
- Nordén, Lars, et al.
(författare)
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Early Exercise of American Put Options : Investor Rationality on the Swedish Options Market
- 2000
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Ingår i: Journal of futures markets. - 0270-7314 .- 1096-9934. ; 20, s. 167-188
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Tidskriftsartikel (refereegranskat)abstract
- Using Swedish equity option data, this study investigates how well the actual exercise behavior of American put options corresponds to the early exercise rules. The optimal exercise strategy is established in two ways. First, the critical exercise price, above which a put option should be exercised early, is computed and compared to the actual exercise price. Second, the exercise value of the option is compared to its market bid price. The results show that most early exercise decisions conform to rational exercise behavior, even though a large number of failures to exercise are found. Most of the faulty exercises can also be discarded after a sensitivity analysis, although several failures to exercise are considered irrational, even after taking transaction costs into account.
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| 4. |
- Nordén, Lars, et al.
(författare)
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The Early Exercise Premium in American Put Option Prices
- 2000
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Ingår i: Journal of Multinational Financial Management. - 1042-444X .- 1873-1309. ; 10, s. 461-479
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Tidskriftsartikel (refereegranskat)abstract
- This study estimates the value of the early exercise premium in American put option prices using Swedish equity options data. The value of the premium is found as the deviation of the American put price from European put-call parity, and in addition a theoretical estimate of the premium is computed. The empirically found premium is also used in a modified version of the control variate approach to value American puts. The results indicate a substantial value of the early exercise premium, where the premium derived from put-call parity is higher than the theoretical premium. The premium also increases with moneyness and time left to expiration, while the effect of interest rate and volatility depends on the moneyness of the option. The modified control variate technique works reasonably well relative the theoretical models. In particular, for deep in-the-money options, this technique is superior.
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