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Summary. Sixteen postmenopausal women receiving conjugated equine oestrogens 1.25 mg/day. continuously, were randomly allocated to add dydrogesterone 20 mg/day for 12 days each calendar month for 3 months and then 10 mg/day in an identical fashion for a further 3 months, or to receive the dydrogesterone doses in reverse sequence. The effects of the two dydrogesterone doses on endometrial histology, vaginal bleeding, and the symptomatic and psychological status were compared. Endometrial samples were obtained around day 10 of progestogen addition. Dydrogesterone, 20 mg, induced uniform, late secretory transformation in all samples; with 10 mg one sample showed mixed early and late secretory features and another demonstrated late secretory changes associated with atypical hyperplasia. Both dydrogesterone doses induced an acceptable withdrawal bleed; most bleeding episodes were ‘spotting’ or normal in amount, and heavy bleeding was reported infrequently. There was one episode of breakthrough bleeding. There were no differences in bleeding patterns between the two dose regimens. Anxiety, and the physical and psychological status were significantly improved after 3 months of therapy. Significant benefits on depression were observed less clearly. There were no differences between the two dydrogesterone doses on anxiety, depression and the physical and psychological status, and, overall, the addition of the progestogen did not antagonize oestrogen benefits.

Low-density lipoprotein oxidation is implicated in the development of atherosclerosis. Plasma susceptibility to oxidation may be used as a marker of low-density lipoprotein oxidation and thus predict atherosclerotic risk. In this study the authors investigated the relationship between plasma susceptibility to oxidation and exposure to automotive pollution in a group of automobile mechanics (n = 16) exposed to high levels of automotive pollution, vs. matched controls (n = 13). The authors induced plasma oxidation by a free radical initiator and they determined susceptibility to oxidation by (1) change in absorbance at 234 nm, (2) lag time to conjugated diene formation, and (3) linear slope of the oxidation curve. Mechanics had significantly higher values (mean +/- standard error) for change in absorbance (1.60 +/- 0.05 vs. 1.36 +/- 0.05; p < .002), and slope (1.6 x 10(-3) +/- 0.1 x 10(-3) vs. 1.3 x 10(-3) +/- 0.1 x 10(-3); p < .001), compared with controls. These results indicate that regular exposure to automotive pollutants increases plasma susceptibility to oxidation and may, in the long-term, increase the risk of developing atherosclerosis.

Here we report the widespread natural occurrence of a known antibiotic and antineoplastic compound, hydroxyurea in animals from many taxonomic groups.Hydroxyurea occurs in all the organisms we have examined including invertebrates (molluscs and crustaceans), fishes from several major groups, amphibians and mammals. The species with highest concentrations was an elasmobranch (sharks, skates and rays), the little skate Leucoraja erinacea with levels up to 250 μM, high enough to have antiviral, antimicrobial and antineoplastic effects based on in vitro studies. Embryos of L. erinacea showed increasing levels of hydroxyurea with development, indicating the capacity for hydroxyurea synthesis. Certain tissues of other organisms (e.g. skin of the frog (64 μM), intestine of lobster (138 μM) gills of the surf clam (100 μM)) had levels high enough to have antiviral effects based on in vitro studies. Hydroxyurea is widely used clinically in the treatment of certain human cancers, sickle cell anemia, psoriasis, myeloproliferative diseases, and has been investigated as a potential treatment of HIV infection and its presence at high levels in tissues of elasmobranchs and other organisms suggests a novel mechanism for fighting disease that may explain the disease resistance of some groups. In light of the known production of nitric oxide from exogenously applied hydroxyurea, endogenous hydoxyurea may play a hitherto unknown role in nitric oxide dynamics.