Polymorphism and Liquid‐Liquid Demixing in Supersaturated Drug Solution

In the field of pharmaceutical compound crystallization, one of the challenging tasks is to control the nucleation and the polymorphism. With these objectives, it becomes clear that an important stage is the phase diagram determination of the considered substance. We have investigated the phase diagram of a pharmaceutical compound in a mixture of ethanol/water. We have observed and characterized, in this phase diagram, a solid‐solid (polymorphism) and a liquid‐liquid phase separation as a function of temperature and drug substance concentration.     

The role of the gonads and the hypophysis in the regulation of hydroxysteroid dehydrogenase activities in rat kidney.

With the exception of 3beta-hydroxy-steroid dehydrogenase all the hydroxysteroid dehydrogenases of adult male and female rat kidney show significant sex differences in their activities. Interference with the organisms endocrine balance (gonadectomy on day 25 of life, hypophysectomy on day 50, a combination of both these operations, administration of testosterone or oestradiol) demonstrates that the sexually differentiated enzyme activities may be classified as androgen or oestrogen dependent, the respective sex hormone acting either in an inductive or repressive manner. The criteria for androgen dependency (microsomal 3alpha- and 20beta-, cytoplasmic 17beta- and 20alpha- hydroxysteroid dehydrogenase) are the feminization of the enzyme activity in male animals after castration and the masculinization of the activity in male and female castrates as well as in normal female animals after administration of testosterone. This latter effect on normal females cannot be a testosterone mediated inhibition of ovarian function since ovariectomy has no effect. For 3alpha-, 20alpha-, and 20beta-hydroxysteroid dehydrogenase the effects of hypophysectomy parallel those of gonadectomy. However, after hypophysectomy the activity of 17beta-hydroxysteroid dehydrogenase falls significantly below the gonadectomized level. The androgen effect on 3alpha and 20beta-hydroxysteroid dehydrogenase is independent of the hypophysis, whereas that of 17beta- and 20alpha-hydroxysteroid dehydrogenase is mediated by the hypophysis.     

ALP,TRAcP and cathepsin K in elasmoid scales: a role in mineral metabolism?

Elasmoid scales from the common carp (and other teleostean fishes) appear to be an exciting new model in the research of mineralized tissues. The presence of alkaline phosphatase (ALP), a marker of mineralization, on both sides of the scale was demonstrated by means of enzyme histochemistry. Tartrate‐resistant acid phosphatase, a marker for mineral degradation and osteoclasts, was observed along the radii, at the same location as the ALP activity on the episquamal side. This points towards an active mineral metabolism, were scale cells are involved in both formation and degradation of the mineralized matrix. Cathepsin K staining revealed the presence of multinuclear osteoclasts along the grooves of the scale. Interestingly, the scales were taken from growing control fish; they were not induced to resorb their matrix. Presence of these enzymes in scale cells, together with the demineralized regions in the centre of the scale suggest a more dynamic mineral metabolism in cyprinid scales then previously observed in other species. Scales are derived from odontode tissues, their formation relies on many the same underlying mechanisms and genes as other mineralized tissues. Moreover, a single scale offers the possibility to culture scale‐forming and ‐degrading cells together on their original matrix. All of the these unique properties substantiate the potential of scales to yield new insights on osteoclasts and regulation of tissue mineralization.