New perspectives on the actions of sulphonylureas and hyperglycaemic sulphonamides on the pancreatic beta-cell.

Sulphonylureas and the hyperglycaemic sulphonamide diazoxide are commonly employed in the therapy of non-insulin-dependent (Type 2) diabetes mellitus and insulinoma, respectively. Stimulatory effects of sulphonylureas on insulin secretion and the inhibitory action of diazoxide are thought to be primarily mediated through modulation of the activity of ATP-sensitive K+ channels (K(+)-ATP channels) in the beta-cell plasma membrane. Certain sulphonylureas are known to be internalised by the pancreatic B-cell.

Studies on the chemical and immunological destruction of insulin-secreting islet cell tumours.

Chemical and immunological destruction of insulin-secreting islet cell tumours were evaluated in vivo and in vitro using the transplantable radiation-induced NEDH rat insulinoma and the derived clonal RINm5F cell line. Administration of a large amount of polyclonal insulin antibody did not affect the development of hypoglycaemia, tumour weights or the survival of insulinoma-bearing rats. Streptozotocin (100 mg/kg body weight) evoked a rapid and sustained decrease of insulin concentrations, accompanied by tumour regression and elevation of plasma glucose.

An immunisation protocol which enhances the frequency of antigen-specific monoclonal antibody production.

An immunisation protocol has been developed for small molecular weight antigens which results in a high percentage of specific hybridomas being produced after cell fusion. An enzyme-linked immunosorbent assay (ELISA) was developed for screening the desired antibodies in the culture supernatants. A conventional immunisation regimen was followed by doses of antigen in sterile water on each of the last 4 days before fusion.