RESUMEN
Our molecular modeling software package, MORPHEUS, allows the study of the interactions between biologically active molecules and their receptors. The package is capable of exploring the multidimensional conformational space accessible to each molecule of the data set under study. By specifying distance constraints or hypothetical receptor binding points, the package is able to filter the biologically accessible conformations of each active compound and deduce a three-dimensional model of the binding sites consistent with the properties of the agonists (or antagonists) under scrutiny. The electrostatic potentials in the environment of a putative binding site can also be investigated using the MORPHEUS package. The molecular modeling module CRYS-X, which is written in FORTRAN 77 for IBM PC machines, is capable of building, displaying and manipulating molecules.
Asunto(s)
Gráficos por Computador , Conformación Molecular , Receptores de Superficie Celular/química , Electroquímica , Microcomputadores , Modelos QuímicosAsunto(s)
Hospitales Veterinarios , Medicina Veterinaria , Animales , Modelos Teóricos , Países BajosRESUMEN
A 2-compartmental analysis of 47Ca kinetics was carried out in 21 patients with primary hyperparathyroidism (pHPT) and 7 healthy control subjects. The results were compared with serum concentrations of calcium, inorganic phosphorus, alkaline phosphatase, and immunoreactive parathyroid hormone (iPTH). The well known increase in exchangeable calcium was found to be not uniform in its subcompartments and with a marked predominance of the osseous fraction. The most important result was the increase of calcium efflux from osseous into extraosseous exchangeable calcium in agreement with the results of Talmage et al. studying PTH actions on calcium flux rates between blood and bone in rats. The increased calcium efflux in pHPT was the only kinetic parameter correlated with serum iPTH. Neither increased calcium accretion indicating high bone turnover, nor serum calcium concentrations and exchangeable calcium fractions correlated with serum iPTH. These results lead to the following conclusions: radiocalcium kinetics provides valuable parameters of bone calcium turnover (osseous exchangeable calcium, bone-calcium efflux, and calcium accretion). Calcium efflux from exchangeable bone calcium, determined kinetically, might be related to PTH induced calcium transport from bone fluid compartment to extracellular fluids according to the concept of Talmage 1977.