Clearance of calcium pyrophosphate dihydrate crystals in VIVO

Authors

  • Daniel J. Mccarty MD,

    Professor And Chairman, Corresponding author
    1. Rheumatology Section, Department of Medicine, the Nuclear Medicine Section, Department of Radiology, and the Department of Pathology, 8700 West Wisconsin Avenue, Milwaukee, Wisconsin.
    • Department of Medicine, The Medical College of Wisconsin, 8700 West Wisconsin Avenue, Milwaukee, WI 53226
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  • David W. Palmer Ph.D,

    1. Assistant Professor of Radiology, Biophysicist, Nuclear Medicine Section, Department of Radiology
    2. Rheumatology Section, Department of Medicine, the Nuclear Medicine Section, Department of Radiology, and the Department of Pathology, 8700 West Wisconsin Avenue, Milwaukee, Wisconsin.
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  • John C. Garancis MD

    Professor Of Pathology
    1. Rheumatology Section, Department of Medicine, the Nuclear Medicine Section, Department of Radiology, and the Department of Pathology, 8700 West Wisconsin Avenue, Milwaukee, Wisconsin.
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Abstract

Synthetic triclinic calcium pyrophosphate dihydrate crystals, uniformly labeled with 85Sr 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 ± 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.

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