The chronically reserpinized rat has been suggested as an animal model for cystic fibrosis. X-ray microanalysis of thick and thin cryosections was carried out to assess elemental redistribution in the submandibular glands and the pancreas of reserpinized rats at the cellular and subcellular level. In the submandibular gland of reserpinized rats, calcium and magnesium concentrations were significantly elevated. Mucus globules, secretory granules, and endoplasmic reticulum were the primary sites of the localization of excess calcium and magnesium. A significant potassium loss from the gland had occurred, particularly from the serous cells. Electron microscopy of conventionally prepared tissue showed marked swelling of the endoplasmic reticulum, especially in mucous cells. The elemental changes in the pancreatic acinar cells of reserpinized rats were reminiscent of elemental redistribution connected with cell death: increased levels of sodium, chlorine, and calcium and decreased levels of magnesium and potassium. Ultrastructural changes included swelling of the endoplasmic reticulum and obstruction of the acinar lumen. It is concluded tha elemental redistribution in chronically reserpinized rats presents interesting parallels with cystic fibrosis.
Alkaline acid- and thermo-stable ribonuclease (RNAase) was assayed in whole mixed saliva from controls and from cystic fibrosis (CF) heterozygotes and homozygotes. There was a significant difference in salivary RNAase activity between control adults (n = 99) and CF heterozygotes (n = 77) (12.6 +/- 0.60 and 36.6 +/- 2.2 U/l, mean +/- SE respectively; p less than 0.001) and between control children (n = 1834) and CF patients (n = 60) (7.9 +/- 0.15 and 47.0 +/- 5.4 U/l respectively; p less than 0.001). A statistically significant difference in salivary RNAase activity was also found between control children and control adults (p less than 0.001) and between CF homozygotes and CF heterozygotes (p less than 0.001). The protein concentration was significantly increased by about 50-60% in saliva both from CF heterozygotes and from CF homozygotes (p less than 0.001 for both groups). It is concluded that in view of the great overlapping in values between the groups, these tests can only be of limited use for diagnostic purposes.
The flow rate, the activity of ribonuclease (RNAase) and the concentration of protein were determined in whole saliva and in parotid and submandibular saliva from patients with cystic fibrosis (CF) and from healthy controls, both before and after stimulation of the salivary secretion. Lower flow rates were found in all types of saliva from CF-patients than in control saliva. Increased activity of RNAase was found in CF saliva, both before and after stimulation of the secretion. The concentration of protein was also increased, but to a lesser degree. No correlation was found between either RNAase activity or protein concentration and severity of the disease or age of the children. It is therefore unlikely that these disturbances are secondary to progression of the disease. Considerable variations in RNAase activity and protein concentration were observed, especially within the CF group, and therefore despite the significant increase in these variables in CF their estimation is of limited diagnostic value.
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