Production of prostaglandins and HETE-compounds by isolated-cultivated bovine aortic endothelial cells.

The main product of AA conversion by BAEC is PGI2. Other PGs were synthesized by confluent cells only in traces with exception of a HHT-like compound which has still to be characterized in more details. A significant release of HETE was only detected when BAEC were destroyed. Under these conditions about 1 pmole/10(5) cells 15- and 12 HETE were released by BAEC. Taken into account the amounts of HETE produced by endothelial cells as well as the partially contradictory activities of 12- and 15-HETE we suggest that an acclerated lipoxygenase activity reflects a lesion of endothelium, but is of minor physiological relevance as compared to the generation of HETE and other eicosanoids by blood cells.

Evidence for succinate production by reduction of fumarate during hypoxia in isolated adult rat heart cells.

It has been demonstrated that perfusion of myocardium with glutamic acid or tricarboxylic acid cycle intermediates during hypoxia or ischemia, improves cardiac function, increases ATP levels, and stimulates succinate production. In this study isolated adult rat heart cells were used to investigate the mechanism of anaerobic succinate formation and examine beneficial effects attributed to ATP generated by this pathway. Myocytes incubated for 60 min under hypoxic conditions showed a slight loss of ATP from an initial value of 21 +/- 1 nmol/mg protein, a decline of CP from 42 to 17 nmol/mg protein and a fourfold increase in lactic acid production to 1.8 +/- 0.2 mumol/mg protein/h. These metabolite contents were not altered by the addition of malate and 2-oxoglutarate to the incubation medium nor were differences in cell viability observed; however, succinate release was substantially accelerated to 241 +/- 53 nmol/mg protein. Incubation of cells with [U-14C]malate or [2-U-14C]oxoglutarate indicates that succinate is formed directly from malate but not from 2-oxoglutarate. Moreover, anaerobic succinate formation was rotenone sensitive. We conclude that malate reduction to succinate occurs via the reverse action of succinate dehydrogenase in a coupled reaction where NADH is oxidized (and FAD reduced) and ADP is phosphorylated. Furthermore, by transaminating with aspartate to produce oxaloacetate, 2-oxoglutarate stimulates cytosolic malic dehydrogenase activity, whereby malate is formed and NADH is oxidized. In the form of malate, reducing equivalents and substrate are transported into the mitochondria where they are utilized for succinate synthesis.

T-ALL related to intermediate cortical/medullary thymocytes displaying functional and surface characteristics of suppressor T cells.

Leukemic cells of a patient with acute T-lymphoblastic leukemia (T-ALL) exhibiting the uncommon clinical feature of hypogammaglobulinemia were examined in terms of surface markers and immunologic functions. Employing various monoclonal reagents reacting with surface antigens present on T cells and additional conventional markers, it was shown that the patient's leukemic cells expressed a phenotypical profile (E-R+, TdT+, C3d-R-, OKT3-, T4-, T6(+), T 10+, T8++) corresponding to the intermediate stage between the cortical and medullary phase of normal thymocyte differentiation. Functionally, they were unable to respond to mitogens or to produce detectable amounts of immunoglobulins or to provide 'help' for allogeneic antibody production while they suppressed the immunoglobulin production of normal B cells by 76% in coculture experiments.