While the organic matrix of bone is composed primarily of collagen(s), the existence of other noncollagenous components was first postulated by Herring and co-workers in the 1960s. The osteoclast number increases dramatically following daily injections of high doses of IL-1 over the calvarial bones of 2- to 3-week old mice. In the extracellular space, the molecules of mature collagen assemble spontaneously into quarter-staggered fibrils (fig. 2); this assembly is directed by the presence of clusters of hydrophobic and of charged amino acids on the surface of the molecules. For example, when there is a pathological increase in bone resorption, as seen in hyperparathyroidism or malignancy, the serum calcium is increased. This is in part because the concentrations of PTH required to produce vasodilation (10 to 100 nM) are substantially above those that normally circulate (low pM). Estrogen replacement stabilizes cancellous bone volume in ovariectomized rats by reducing the rate of bone turnover; by reestablishing a neutral or positive balance between bone formation and bone resorption; and by preventing the destruction of trabecular plates. Thus, in both men and women it is probably that androgens and estrogens each have important, yet distinct, functions during bone development and in the subsequent maintenance of skeletal homeostasis. The dopamine transporter (DAT) is believed to control the activity of released dopamine (DA) into presynaptic terminals (or possibly other DAT-expressing cells). Rickets and osteomalacia are frequently associated with Fanconi’s syndrome, a disorder characterized by phosphaturia and consequent hypophosphatemia, aminoaciduria, renal glycosuria, albuminuria, and proximal renal tubular acidosis. Infusion of either a PTHrP antagonist peptide or a monoclonal anti-PTHrP antibody into the uterine lumen during pregnancy resulted in excessive decidualization. While long-term changes in phosphate balance depend on these variables, short-term changes in phosphate concentrations can occur due to redistribution of phosphate between the extracellular fluid and either bone or cell constituents. Any attempt to understand the cellular basis for the anabolic actions of PTH and PTHrP must take into account their histomorphological effects. The binding of amylin to osteoblast-like cells was demonstrated soon after the discovery of the peptide and binding of amylin and stimulation of cyclic AMP production were also demonstrated in a pre-osteoblastic cell line. Enjoy the book. We enjoyed editing it for you.