Inhibition of bone resorption in vitro by compound 48/80.

The mechanisms that control cycles of bone formation and bone resorption are not well understood. In this report we provide evidence that compound 48/80 is a potent inhibitor of bone resorption in vitro. Resorption was assessed by the release of calcium-45 from pre-labelled newborn mouse calvaria that were treated with compound 48/80 and/or parathyroid hormone (PTH) in organ culture.

Multiwell chamber chemotaxis assays: improved experimental design and data analysis.

The chemotaxis assay using the Boyden transfilter technique has become widely used in recent years for assessing migratory responses of a wide variety of cell types. In the study reported here we examined the migratory responses of mouse peritoneal macrophages using a multiwell chamber. The experiments were designed to analyze the components of variance in the assay method, to optimize the experimental design, and to develop objective statistical criteria for choosing among experiments with disparate results.

Bone-derived macrophage chemotactic factors: methods of extraction and further characterization.

Mononuclear phagocytes have been implicated as important cellular elements in the process of bone resorption. We have postulated that the recruitment and migration of mononuclear phagocytes to bone occurs via a mechanism(s) in which bone-derived chemotactic factors (BDCF) are released from foci undergoing resorption. In the experiments presented here we have used newborn mouse calvaria and examined a variety of extraction protocols, both dissociative and non-dissociative, as means of obtaining stable and reproducible chemotactic activity for mouse peritoneal macrophages.

Bone resorption and humoral hypercalcemia of malignancy: stimulation of bone resorption in vitro by tumor extracts is inhibited by prostaglandin synthesis inhibitors.

Extracts of tumors from patients with humoral hypercalcemia of malignancy (HHM) were tested using an in vitro bone resorption assay in order to investigate the pathogenesis of the hypercalcemia. Bone resorption was assessed by comparing the percent release of previously incorporated 45Ca from paired halves of newborn mouse calvaria. Saline extracts of three out of five tumors from HHM patients caused a significant increase in 45Ca release relative to controls.