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The crystal structure of Cabergoline, a potent and long lasting prolactin lowering agent interacting with the D2 dopamine receptors, has been determined by X-ray diffraction data. The structural data represent the starting point for a computational study, where the molecular mechanisms approach was used to explore the motion of all unconstrained torsion angles. Two different conformations related to energetic minima have been found, one of them in agreement with the experimental crystal structure. Both conformations are shape compared with Bromocriptine and Lisuride, two dopaminergic ergoline derivatives with C-8 beta and C-8 alpha substituents of the ergoline ring, respectively. We observe that the C-8 beta Cabergoline assumes the overall three-dimensional features of C-8-alpha-ergolines in one of its low-energy conformations.

The aim of the present study was to evaluate the surface morphology and the permeability of dentine after different acid treatments: polyacrylic acid, maleic acid, phosphoric acid and saline solution as control. Dentine permeability was expressed as hydraulic conductance. All the acid treatments removed the smear layer and increased the dentine permeability.

It is well known that a typical painful feeling is caused by impact of different agents and by thermodynamic conditions upon the dentine layer of the tooth. Therefore the action by artificial solutions should be tested to study how the induced modifications might inhibit the pain. The aim of the present study is to evaluate by scanning electron microscopy (SEM) the morphology of dentine surface after different chemical treatments. Oxalate solutions are able to produce a layer of large crystals, while acid solutions remove the smear layer and open the dentinal tubules.

It has been proposed that fluoride ion might actively enter into the basic structural framework of the bone, within its main constituent, the hydroxyapatite (HA), by substituting systematically the OH- ion in the crystal chemical formula Ca5[(PO4)3OH]. Accurate compositional studies have become necessary in order to explain an eventual stabilizing effect. Loss in weight (TG) and chemical reaction (DTG) while varying the temperature have been carried out for the first time on specimens under normal conditions and after fluo-calcic treatment, in parallel with accurate chemical compositional determinations by atomic absorption analysis. Our investigation shows that the new structure present after treatment is mechanically stable and proves more resistant to osteolytic processes.

Hydroxyapatite has been studied as a substance suitable for surgical substitution of bones and teeth with emphasis on its biocompatibility. The present work tries to identify the characteristics of this material either from the chemico-physical-structural point of view, or from the technological one, evaluating the best performance. By X-ray, i.r., thermal, chemical and SEM analyses, the relationship of different phenomena involved in the sintering was evaluated. Technological tests demonstrated the stability and the workability characteristics. In particular, the influence of CO2 was studied, in connection with the most suitable technique for hydroxyapatite (HAP) sintering, considering the eventual aims and requirements for industrial production.

(I): C19H22N4O2 (Registry No. 95688-34-9), m.p. greater than 573 K, Mr = 338.4, orthorhombic, P2(1)2(1)2(1), a = 8.392 (2), b = 13.004 (2), c = 15.676 (5) A, V = 1710.7 (7) A3, Z = 4, Dx = 1.31 Mg m-3, Mo Ka radiation, lambda = 0.71069 A, mu = 0.08 mm-1, F(000) = 720, T = 293 K, final R = 0.051 for 990 independent reflexions. (II): C26H33N3O3.1/2C7H8 (Registry No. 54370-23-9), m.p. 427-429 K, Mr = 481.64, monoclinic, P2(1), a = 11.595 (4), b = 14.274 (2), c = 16.103 (4) A, beta = 100.19 (3) degrees, V = 2623 (1) A3, Z = 4, Dx = 1.22 Mg m-3, Mo Ka radiation, lambda = 0.71069 A, mu = 0.07 mm-1, F(000) = 1036, T = 293 K, final R = 0.064 for 2738 independent reflexions. Two independent molecules constitute the asymmetric unit, together with a toluene molecule. Parallel investigations of the title compounds by single-crystal X-ray analysis and theoretical calculations have converged in showing an extended configuration of the side chain attached at the C8 atom of the ergoline nucleus.