values for ethanolamine, 1-aminopropan-2-01s and their phosphate derivatives, with the kinase and phospho-lyase enzymes respectively, indicated that the pathway in Pseudomonas sp. N.C.I.B. 8858 was concerned with 1-aminopropan-2-01 degradation. (L-1-Aminopropan-2-01 is a metabolite of aminoacetone, derived from L-threonine, and D-1-aminopropan-2-01 is a fragment of vitamin B12 compounds.) It was noteworthy that the addition of (NH4)$304 to cultures growing on DL-1-aminopropan-2-01 as N source did not repress kinase or phospho-lyase formation. It appears likely that the ability to degrade ethanolamine via its 0-phosphate ester is widespread. A small-scale survey of bacteria has revealed several members of the order Eubacteriales with this ability. it is clear that ethanolamine kinase functions in a biodegradative mode in these bacteria, in contrast with its biosynthetic function in higher organisms. The possibility that a biodegradative isoenzyrne form of ethanolamine kinase may operate in mammals is not ruled out and indeed is supported by isotopicevidence.
Summary
The glucocorticoid binding properties and cytolethal responsiveness of leukaemic cells were studied in vitro in seven patients with hairy‐cell leukaemia (HCL) and five with chronic lymphocytic leukaemia (CLL). Substantial levels of glucocorticoid binding were detected both in whole cell and cytosol preparations from all patients although the level of binding by HCL cells always exceeded that of CLL cells (P>0.05). In both leukaemic cell types the uptake and binding of prednisolone in vitro was significantly greater than that of dexamethasone (P>0.05). CLL cells showed a variable dose‐related cytolethal response to methylprednisolone sodium succinate (MPSS) treatment in vitro although cytolytic effects were not marked in the usual pharmacological dose range (10‐5‐106m). Treatment of CLL patients with conventional doses of prednisone for extended periods or high intravenous infusions of MPSS over shorter periods had no consistent effect on the in‐vitro level of steroid binding or the cytolethal responsiveness of CLL cells to glucocorticoid treatment. Although HCL cells proved highly resistant to the cytolethal effects of MPSS in vitro, the substantial binding of glucocorticoids by leukaemic cells from all HCL patients indicates the potential value of steroid therapy in this disease should be explored further.
Seven per cent (10/145) of hybridomas raised against partially purified activated glucocorticoid receptor from rat liver produced monoclonal antibody to receptor. Six IgM secreting clones selected for further investigation bound equally well to activated and non-activated receptor from fresh rat liver, but significantly less well (11-25 per cent) to receptor from frozen rat liver. No interaction was found with oestrogen receptor from rat uterus but extensive cross reaction occurred with progesterone receptor. Although none of the antibodies bound to glucocorticoid receptor from human or porcine liver or lymphoid cells, several cross-reacted with mouse liver glucocorticoid receptor. Immunoelectroblotting of proteins from fresh and frozen rat liver cytosol showed the antibodies bound to 90,000 and 40,000 MW forms of receptor respectively. Immunostaining of both frozen and paraffin embedded sections of rat tissue showed that receptor is preserved during fixation and processing of tissues. Using both indirect immunoperoxidase and immunogold silver staining methods, the pattern of receptor staining observed correlates with the known glucocorticoid responsiveness of the tissues studied.
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