The investigation of cytosolic phospholipase A2 using ELISA.

Two studies of the behaviour of cytosolic phospholipase A(2) (cPLA(2)) in the red blood cell (RBC), as measured by ELISA, are described. In the first study we show a significant increase in cPLA(2) in patients with schizophrenia compared to controls and suggest that this measure, if corroborated, could be used as a diagnostic marker. In a second study we found that washing the RBC introduced an unknown confounding variable which led us to reject this study. A subsequent investigation of washing red cells showed that the washing effect may be due to a plasma factor likely to be more than 5kDa MW which can be removed from red cells by washing with buffers. When the cells are washed, the concentration of cPLA(2) in the red cell, as measured by ELISA, significantly increases. We advise against washing the red cell in any study that involves measuring cPLA(2) by ELISA.

On the relationship between methylnicotinate-induced skin flush and fatty acids levels in acute psychosis.

Vasodilation induced by methylnicotinate, a fatty acid- and cyclooxygenase-dependent process, is reduced or absent in patients with schizophrenia. This phenomenon has been suggested to be useful as a diagnostic test for the illness. To determine whether reduced flushing is specific to schizophrenia and is caused by a deficiency in membrane fatty acids, the extent of topically applied methylnicotinate-induced vasodilation was measured in 23 subjects with schizophrenia, 20 subjects with bipolar disorder and 34 healthy volunteers along with red cell fatty acid concentrations and measures of clinical severity. Although there was a significant decrease in an estimate of vasodilation (erythema) compared with healthy volunteers in both schizophrenia and bipolar groups, the schizophrenia group responded significantly less than subjects with bipolar disorder. The reduction in the bipolar group was partly due to a delayed vasodilatory reaction, an effect not observed in subjects with schizophrenia. In subjects with schizophrenia, there were no significant correlations between methylnicotinate response and fatty acid concentrations. The authors conclude that the methylnicotinate procedure can differentiate schizophrenia from other serious mental illness. The methylnicotinate insensitivity in schizophrenia, however, is likely to be due to a deficiency in the fatty acid precursors required for the vasodilatory reaction.