Clearance of calcium pyrophosphate dihydrate crystals in VIVO

Abstract

Synthetic triclinic calcium pyrophosphate dihydrate crystals, uniformly labeled with *'Sr and 45Ca, were injected into the knee joints of 2 normal adult rabbits and 2 rabbits previously injected repeatedly with autologous blood. The "half clearance time" of the injected crystal mass was 20.4 and 19 days from control joints, nearly identical to previously reported values in 6 rabbits (19.1 f 1.4), and 28.8 and 34 days from the joints injected with blood, a significant difference (P < 0.05).Iron stains showed hemosiderin granules in the superficial synovium in these joints. Electron microscopy showed crystals with a molar calcium/phosphorus ratio of 1.0 and particles containing iron within synovial cells. We hypothesize that the decreased clearance rate from hemosiderotic synovium is due to inhibition of one or more intracellular pyrophosphatases by iron.A method for determination of the synovial clearance rates of radiolabeled synthetic triclinic cal-

Characteristics of the arthropathy described in hereditary hemochromatosis

“…In vitro studies show that iron inhibits pyrophosphatase, suggesting that excess iron may promote pyrophosphate deposition in the synovium or cartilage (36). Additionally, accumulation of calcium pyrophosphate may be facilitated by reduced clearance in the setting of synovial siderosis (37). Whereas both ferric and ferrous iron influence CPPD formation, to date chondrocalcinosis has not been definitively linked to the level of iron overload (38,39).…”

Intervertebral chondrocalcinosis: an exercise in differential diagnosis in palaeopathology

“…For the diagnosis of the cause of chondrocalcinosis in skeletal remains, characterisation of calcific deposits in the intervertebral discs or other locations is clearly desirable (McCarty, 1992). However, for archaeological material the interpretation of results is often complicated by diagenesis.…”

Calcium Phosphates in Biological and Industrial Systems

“…They are carbonated apatites and exhibit non-apatitic environments. 89 The precipitation of the neo-formed crystals can also be boosted by release of calcium, phosphate ions, or rise in the pH that may locally increase the supersaturation ratio in the vicinity of the implant surface. This phenomenon can be favored by hydrolysis reactions of the material constituents.…”

“…It occurs on several biomaterial surfaces such as collagen, Polyactiv®, Bioglass®, apatites, titania gels, corals, either in vivo or in vitro, in cell culture media. 89 On other substances, such as titanium, for example, this layer may also be formed by simple heterogeneous nucleation in supersaturated fluids. Two ways of forming this layer can be recognized depending on the interaction of the biomaterial with the body fluids.…”