Phospholipid changes in synaptic membranes by lipolytic enzymes and subsequent restoration of opiate binding with phosphatidylserine.

A study has been made of the role of phosphatidylserine in stereospecific opiate binding to neural membranes, utilizing specific lipolytic enzymes to attack the lipid. At very low concentrations phospholipase A2 from bee venom will preferentially hydrolyze C22:6-fatty acid; and even after a few percent of the total phosphatidylserine is hydrolyzed, opiate binding is greatly inhibited. The addition of brain phosphatidylserine will restore opiate binding; however, when the inhibition approaches 50% restoration is only partial.

Enhancement of opiate binding by various molecular forms of phosphatidylserine and inhibition by other unsaturated lipids.

A study was undertaken on the possible involvement of phospholipids on stereospecific opiate binding to a rat brain membrane fraction comprised mainly of synaptic membranes. The addition of acidic phospholipids such as phosphatidylserine, phosphoinositides, and phosphatidic acid significantly enhanced opiate binding. With the exception of phosphatidylserine, when the acidic phospholipids contained a polyunsaturated acyl group, they were actually inhibitory, along with neutral phospholipids derived from brain.

Lymphocyte response to mitogens in progressive systemic sclerosis.

Lymphocyte responses to the mitogens phytohemagglutinin P(PHA-P), concanavallin A (Con A), and pokeweed (PWM) were studied in 18 patients with progressive systemic sclerosis (PSS). A subgroup of these patients with multisystem involvement showed a significantly decreased lymphocyte response to both Con A and PWM when compared to normal controls. However those PSS patients with myositis, although having multisystem involvement, had normal lymphocyte response to all three mitogens.