Oncocytic adenoma of the parotid gland with psammoma bodies.

An unusual slow-growing tumor was found in the superficial lobe of the right parotid gland. It was multilobulated and encapsulated and consisted of sheets of epithelial oncocytes and minor foci of myoepithelium and ducts. Psammoma bodies were abundant. An antibody directed against keratin protein was localized in all tumor cells and in ductal but not acinar elements of adjacent parotid tissue. Ultrastructurally, the neoplastic cells proved to be ductal epithelial and myoepithelial oncocytes.

Primary amyloidosis A. Immunohistochemical and biochemical characterization.

Primary "idiopathic" amyloidosis is usually related to immunoglobulin light chain (AL) associated with immunocytic dyscrasias, while secondary "reactive" amyloidosis (AA) is related to serum amyloid A protein (SAA) and typically occurs with chronic inflammation, malignancy, or familial Mediterranean fever. In the present study, amyloid fibril protein extracted from frozen and paraffin-embedded tissue from a patient (CAR) with primary systemic amyloidosis proved to be AA protein by immunohistochemical, immunochemical, and amino terminal sequence. Extracts from both frozen and formalin-fixed paraffin-embedded kidney and spleen yielded similar monomers and dimers of the AA protein. The additional high-molecular-weight bands and a distinct 12,000-dalton fragment in the amyloid protein extracted from the formalin-fixed paraffin-embedded lung suggest that different processing of proteins, ie, by polymerization and/or degradation, may occur in different organs.

Atrial natriuretic factor receptors in cultured renomedullary interstitial cells.

To gain further insight on the cell types that may mediate the effects of atrial natriuretic factor (ANF) in the renal medulla, we determined the distribution and function of biological (B) and clearance (C) receptors of ANF in renomedullary interstitial cells (RMIC). Studies were performed in the 3rd-17th passages of RMIC obtained from a primary culture of the rat renal medulla. Electron microscopy of the cultured cells showed the typical morphological features of RMIC "in vivo," including prominent lipid droplets. RMIC have a very high density of high-affinity specific binding sites of ANF-(1-28) [23,000 sites/cell; dissociation constant (Kd) = 50 pM]. There was only minimal binding of C-ANF-(4-23) (less than 2,500 sites/cell), a specific ligand of C-ANF receptors. ANF-(1-28) markedly increased guanosine 3',5'-cyclic monophosphate (cGMP) from 1.3 +/- 0.3 to 106 +/- 22 pmol cGMP/10(6) cells [50% effective dosage (ED50) = 1.2 nM]. The effect of ANF-(1-28) on cGMP was nearly additive to that of sodium nitroprusside and was not potentiated or antagonized by C-ANF-(4-23). The density of guanylate cyclase-coupled B-ANF receptors and the ANF-induced increase in cGMP in RMIC are higher than those reported to date in other target cells. This suggests that RMIC may mediate some of the known effects of ANF in the renal medulla.