Seasonality of nitrogen partitioning (non-structural vs structural) in the leaves and woody tissues of tropical eucalypts experiencing a marked dry season

Numerous studies have shown that internal nitrogen (N) translocation in temperate tree species is governed by photoperiod duration and temperature. For tropical tree species, the seasonality of rainfall is known to affect growth and foliage production, suggesting that efficient internal N recycling also occurs throughout the year. We tested this hypothesis by comparing the N budgets and N partitioning (non-structural vs structural N) in the different organs of 7-year-old Eucalyptus urophylla (S.T. Blake) × E. grandis (W. Hill ex Maiden) trees from a plantation in coastal Congo on poor sandy soil. The trees were sampled at the end of the dry season and late in the rainy season. Lower N concentrations and N investment in the non-structural fraction were observed in leaves during the dry season, which indicates resorption of non-structural N from senescing leaves. Stem wood, which contributes to about 60% of the total biomass of the trees, accumulated high amounts of non-structural N at the end of the dry season, most of which was remobilized during the following rainy season. These results support the hypothesis of efficient internal N recycling, which may be an important determinant for the growth potential of eucalypts on N-poor soils. Harvesting trees late in the rainy season when stem wood is depleted in non-structural N should be recommended to limit the export of nutrients off-site and to improve the sustainability of tropical eucalypt plantations.

[Misoprostol in case of termination of pregnancy in the second and third trimesters. Trials]

Termination of pregnancies (TOP), in the second and third trimesters, require feasibility to induce labour with unfavorable cervix. Combination therapy is then usually necessary. Misoprostol use is out of marketing authorization in obstetrics but is widely used for many years in TOP in the 2nd and 3rd trimesters of pregnancy. Most randomized trials comparing misoprostol to other molecules available for TOP (gemeprost, dinoprostone, sulprostone) show that misoprostol is at least as effective with fewer side effects often especially if using adapted doses and routes of administration. Sometimes, products with a marketing authorization have been used with caution due to adverse effects more or less reported with misoprostol. There is, however, no conclusive evidence in the literature showing the superiority of a dose or route of administration of misoprostol compared to another. However, sublingual and oral seem to be preferred by patients than the vaginal route which remains the most evaluated and effective route. In summary, the use of vaginal misoprostol is the first-line treatment in medical abortion in the 2nd and third trimester, in combination with at least 200mg of mifepristone 36 to 48 hours before, at a dose of 400 μg every 4 to 6 hours. However, its use must be given with caution in cases of uterine scar, but cannot be forbidden for the sole justification of not having a marketing authorization. It will nevertheless warrant information to patients and allow a reduction at least half doses. The multi-scarred uterus still justifies a lower starting dose in the minimum effective doses (100 μg or less) as a corollary, increased induction-expulsion delay. The risk-benefit balance must be discussed with the patient. The agent without any pharmacological action solely or in combination (laminar dilapans, Foley catheter or double balloon) is particularly interesting in the case of uterine scar or maternal vascular risk but requires further evaluation by other research with adequate power and methodology before recommending for systematic routine use.