Effect of some flavonic compounds and ascorbic acid on lactoferrin stimulation of erythrocyte glycolysis and Na+/ K+-atpase activity.

The aim of the present study was to assess if some flavonic compounds (quercetin, piceatannol and apigenin) and ascorbic acid could interfere with the Lf stimulatory effect on the erythrocyte function. Quercetin (1.5 microM) and piceatannol (30 microM) showed an additive effect on Lf stimulation of Na+/ K+-ATPase when used together with Lf.

Lactoferrin stimulates erythrocyte Na+/K+ -adenosine triphosphatase: effect of some modulators of membrane phosphorylation.

We studied the effect of some modulators of signal transduction on the erythrocyte Na+/ K+-ATPase. Go6976 and Go6983 (protein kinase C inhibitors) showed a stimulatory effect and calyculin A (protein phosphatase inhibitor) exerted an inhibitory effect on the Na pump activity. Some of the tested modulators of cell-signaling [protein phosphatase(s), phosphodiesterase, calmodulin and some protein kinases] interfered with the lactoferrin (Lf) stimulatory effect on the sodium pump.

Lactoferrin-protector against oxidative stress and regulator of glycolysis in human erythrocytes.

Binding of lactoferrin (Lf) to its membrane receptors requires an electron for the reduction of Fe(3+)LF to Fe(2+)LF. It is possible that glyceraldehyde -3-phosphate dehydrogenase, a glycolytic enzyme part of the erythrocyte membrane, delivers that electron. Then Lf, obtaining an electron from the coenzyme NADH, might stimulate glycolysis, which requires the oxidised state of the coenzyme NAD+.

Essential metal ions alter the lactoferrin binding to the erythrocyte plasma membrane receptors.

The effect of metal ions at a concentration of 10(-8) to 10(-5) M [using their salts: ZnCl2, CdCl2, LiCl, CuSO4, NiSO4, Al2(SO4)3, (NH4)2MoO4 on the lactoferrin (Lf) binding to the erythrocyte membrane receptors was studied. In the absence of metal ions, Scatchard's analysis showed the existence of two kinds of binding site: one with high affinity and low capacity, and the another with low affinity and high capacity. All these metals, excluding Zn2+ and Cd2+, at a concentration 10(-5) M decreased the affinity of Lf binding (Ka1) to the high-affinity receptors.

Superoxide dismutase and lipid-bound sialic acid in sera from children with cancers and juvenile chronic arthritis.

Both experimental and epidemiological studies suggest that patients with autoimmune and other chronic inflammatory diseases are more prone to develop cancer. The aim of the present investigation is to find some typical differences between the content of lipid-bound sialic acid (LSA) and the activity of superoxide dismutase (SOD) in sera from children with neoplastic diseases and juvenile chronic arthritis (JCA). Our results show 30% lower SOD activity in the sera from children with cancer compared with the sera from children with JCA.