| Abstrakt: |
Extract: Centrifuged pellets of turbid parotid saliva from cystic fibrosis (CF) patients and non-CF subjects, obtained from saliva kept at 2° for 10 min, had the electron microscope appearance of amorphous, round particles, and were thought to be colloidal aggregates of organic material. Drops of turbid saliva, from samples incubated for 2 hr at 2° or 37°, additionally contained discrete, electron-dense crystals having well defined angular morphology: usually cubic, rectangular, or approximately hexagonal. The inhibitors, urea, guanidine hydrocnloride, and EDTA, resulted in no crystals being observed. Selected area electron diffraction from individual crystals showed predominantly hexagonal, rectangular, or square diffraction patterns. The hexagonal and rectangular patterns could be indexed as coming from hydroxyapatite. A transition from the hexagonal to the rectangular pattern and back to the hexagonal pattern could be obtained from individual crystals tilted in the electron microscope. The square diffraction pattern may be from octa-calcium phosphate or brushite.Polyacrylamide gel disc electrophoresis of the parotid saliva indicated that the sparingly soluble proteins in the 2° and 37° pellets comprised proline-rich proteins and a calcium-precipitable, trichloroacetic acid (TCA)-precipitable phosphoprotein, which fluoresced with amido schwarz and Coomassie brilliant blue G250.Speculation: The sparingly soluble colloidal protein droplets and precipitating calcium phosphate crystals are probable causes of parotid duct obstruction and dental calculus in CF patients and heavy calculus formers. |
