Hydrophilic gel containing nanocapsules of diclofenac: development, stability study and physico-chemical characterization.

The purpose of this work was to develop and to characterize hydrophilic gels containing nanocapsules (NC) of diclofenac (DIC). Nanocapsules suspension of poly-epsilon-caprolactone containing free acid diclofenac were prepared by nanoprecipitation. The pH value of the nanocapsules suspension was 5.70 +/- 0.03 and the mean sizes of the NC were in the sub 300 nm range. Drug incorporated into the nanocapsules was close to 100% and the encapsulation efficiency was 104.1% +/- 3.5%. Diclofenac nanocapsules suspension (1 mg/mL) was incorporated in a Carbopol gel matrix fournishing a formulation with 0.5 mg of DIC/g. The gel stability was evaluated in terms of the macroscopic and microscopic aspect, rheological properties, pH and drug recoveries. As a result, we obtained a suitable formulation for topical use presenting a non-Newtonian behaviour with plastic properties and with intact nanostructures in the gel matrix after 3 months storage atroom temperature (freeze-fracture electron microscopy).

[Autoradiographic investigations on postnatal proliferative activity of the telencephalic and diencephalic matrix-zones in the axolotl (Ambystoma mexicanum), with special references to the olfactory organ (author's transl)]. / Autoradiographische Untersuchungen der postnatalen Proliferationsaktivität in den Matrixzonen des Telencephalons und des Diencephalons beim Axolotl (Ambystoma mexicanum), unter Berücksichtigung der Proliferation im olfactorischen organ.

The localization and proliferative activity of the matrix-zones has been investigated in the telencephalon and in the diencephalon of 21 axolotls (Ambystoma mexicanum) by means of autoradiographs, after injection of tritiated thymidine at different stages of the postnatal life. There are no previous detailed autoradiographical reports on postnatal brain development in the axolotl. Matrix-zones (i.e. ventricular and subventricular zone) exist in the dorsal part and in the ventral part of the telencephalon, we have found these also in the diencephalon in the wall of the preoptic recessus and ventrally of the habenula. The quantitative part of this study indicates high values of the labeling-index in the early postnatal stages. Then, the labeling-index decreases, but also in 3 years old specimens labeled cells were observed in the matrix-zones of the telencephalon; therefore a few of proliferative capacity remains in the central nervous system of adult axolotls. Labeled cells were also found in the olfactory organ of early postnatal and adult axolotls; these are neuroblasts which have relevance for the regeneration of the forebrain.