No abstract

A continuous line of cells (A6) derived from toad kidney has been shown to form epithelia in culture that manifest aldosterone-stimulatable transepithelial sodium transport. In this study an efficient filtration assay for nuclear binding of [3H]aldosterone was validated. Specific high-affinity aldosterone and corticosterone binding sites in the particulate (nuclear-enriched) fraction were characterized in intact epithelia. Despite metabolism of both steroids, two high-affinity binding sites for each were demonstrable: aldosterone, K'd1 = 0.85 (+/- 0.19) X 10(-10) and K'd2 = 1.6 (+/- 0.42) X 10(-8) M; corticosterone, K'd1 = 0.5 (+/- 0.31) X 10(-10) and K'd2 = 0.32 (+/- 0.19) X 10(-8) M. Analogue competition-binding studies indicated a qualitative difference in the two sites and co-occupancy of both sites by the two steroids. The sodium transport response to aldosterone and corticosterone approximated a linear function of occupancy of the lower affinity sites. Although the lower affinity sites resemble mammalian glucocorticoid receptors in terms of relative binding affinities for analogues, we conclude that they are the receptors which mediate the aldosterone and corticosterone stimulation of Na+ transport in these epithelia.

The aim of this study was to establish how effective is the use of immunohistochemistry on formalin-fixed bone marrow in diagnosing low-grade B-cell neoplasms. We investigated a series of 41 consecutive patients with bone marrow involvement for whom no other diagnostic tissues were available. The sections were stained with the following antibodies: CD3, CD20, CD79a, CD5, CD10, CD23, anti-cyclin D1 and kappa and lambda light chains. Antigen retrieval was performed using either a microwave oven or a pressure cooker. Labelling was performed with an avidin-biotin-peroxidase labelling system. A final diagnosis was reached in 37 out of 41 cases (90%): B-chronic lymphocytic leukaemia (15 cases), follicular lymphoma (10 cases), mantle-cell lymphoma (eight cases) and lymphoplasmacytoid lymphoma/immunocytoma (four cases). In the remaining four cases, a generic diagnosis of low-grade B-cell neoplasm was made. The immunophenotyping of formalin-fixed marrow is a useful technique for diagnosing most of the low-grade B-cell neoplasms.

Hamsters inoculated with scrapie virus show a dramatic hypersensitivity to serotoninergic drugs, developing a behavioral syndrome not unlike that obtained with pharmacologically induced lesions of the raphe nuclei. In an attempt to explain the state of hypersensitivity and to determine whether or not serotoninergic neurons were targets of the scrapie virus, pre- and postsynaptic serotoninergic sites were studied in the cerebral cortices of scrapie-infected and sham-inoculated hamsters. [3H]Imipramine binding and the uptake of endogenous 5-hydroxytryptamine (5-HT, serotonin) in synaptosomes prepared from scrapie-inoculated animals were not different from those of controls. This suggests integrity of the serotoninergic neurons in scrapie-infected hamsters. In contrast, affinity for the 5-HT1 receptor (which modulates inhibitory response) was diminished whereas that for the 5-HT2 receptor (which modulates excitatory response) was increased. This "imbalance" between the two receptors which is amplified in in vivo responses may account for the 5-HT hypersensitivity. The alteration in the affinity of the two postsynaptic 5-HT receptors supports the observation that scrapie virus alters cell plasma membranes.