Normal rat bone maturation has been studied using biochemical methods and hydrazine separation of matrix and mineral for X-ray diffraction. In the bone, the amount of mineral increases between 4 and 22 weeks of age, while in the matrix, the ratio of noncollagenous protein to collagen progressively decreases. In mineral, in the absence of serum ion changes, growth in mean crystal size appears to be the determinant of the changing ratios of calcium, magnesium, carbonate, and phosphorus, and of the increasing mineral density.

Over the last years the treatment of chronic leg ulcers has developed from a merely symptomatic to a differentiated therapy. Although more than 90% of the ulcers are of vascular origin, many other causes are possible. A survey of the various triggers of chronic ulcers of the lower limb is given. Vascular, hematological, neuropathic, infectious, malignant and chemico-physical causes are discussed. New findings regarding hemostatic defects as the basis of thrombophilia and ulcers are presented.

To study the effects of bicarbonate and magnesium on bone, mild acidosis and/or hypermagnesemia were produced in growing rats by feeding ammonium chloride and/or magnesium sulfate. Bone composition, quantitative histomorphometry, and mineral x-ray diffraction (XRD) characteristics were measured after 6 wk of treatment. The results demonstrated that both acidosis (decreased HCO3) and hypermagnesemia inhibited periosteal bone formation, and, when combined, results were summative; and the previously observed in vitro role of HCO3- and Mg2+ as inhibitors of crystal growth were confirmed in vivo. XRD measurements demonstrated that decreased plasma HCO3 resulted in larger crystals and increased Mg resulted in smaller crystals. However, the combined XRD effects of acidosis and hypermagnesemia resembled acidosis alone. It is postulated that the final composition and crystal structure of bone are strongly influenced by HCO3- and Mg2+, and the effects are mediated by the combined influence on both osteoblastic bone formation and the growth of hydroxyapatite.

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