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Biomedical subjects

A Maneva

Publications and source records attributed to A Maneva.

8 recordsLinked to original sources
PubMed1999

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. In the presence of Zn2+ and Cd2+, only the low-affinity binding site was found. Significant inhibition on the affinity (Ka2) of the low-affinity class of receptors showed Zn2+, Al3+, and Mo6+. Depending on their concentration (10(-8)-10(-5) M), these ions enhanced to a different extent, the binding capacity of the both types receptors, but the effect did not correspond to the applied doses. Several explanations of the mechanism for influence of the metal ions on the Lf-receptor interaction is discussed.

Biological Transport↗
PubMed1998

Effect of lactoferrin on the phagocytic activity of polymorphonuclear leucocytes isolated from blood of patients with autoimmune diseases and Staphylococcus aureus allergy.

Phagocytic number (PN) and phagocytic index (PI) of neutrophils isolated from blood of patients with autoimmune diseases, allergy to Staphylococcus aureus and from blood of healthy individuals were examined. Our results concerning the influence of lactoferrin (Lf); (6.7 mg/l) on the PI of PMN showed that: 1) Lf enhances reliable PI of PMN at the 30-th minute starting the phagocytic reaction in patients with autoimmune disease in an active stage, in blood donors treated as healthy with the presence of autoantibodies, in patients with autoimmune diseases and proved autoantibodies against tissue, cell antigens and collagen, 2) Lf influences non-significantly PI of PMN in patients with autoimmune collagen diseases in remission, 3) Lf increases PI of PMN with 19% only in 58% from the assessed patients with Staphylococcus aureus, and 4) Lf decreases non-significantly PI of PMN in the healthy controls. Our studies on the effect of Lf on the phagocytic activity of PMN suggest that Lf has stronger effect on the PN compared to the PI: 1) Lf enhances with 86% the PN in patients with Staphylococcus aureus, 2) Lf increases PN of PMN in all of the assessed patients with autoimmune collagen diseases in active stage (mean with 72%), and 3) Lf increases PN of PMN in 4 from the 5 investigated healthy controls (mean with 22%). Our results show a "corrective" effect of Lf on the phagocytic functions in the investigated groups of patients. The possible mechanisms, by which Lf increases PN and PI of neutrophils, is discussed: 1) they may concern the antioxidative properties of Lf to block the iron ions in their catalytic inactive form or to take part as ferric-Lf in an oxidative-reduction processes on the plasma membrane and controlling transmembrane transport systems, 2) Lf decreases the negative surface charge and thus enhances the adherent ability of the PMN. Probably to this stimulated adherent ability dues the increased ingestion of bacteria in the presence of Lf, and 3) The "changed" membrane of PMN may have higher number receptors for Lf to bind more molecules of exogenous Lf. The increase of Lf binding which enhances the adherence and aggregation of neutrophils, facilitates the phagocytosis.

Adolescent↗
PubMed1995

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. LSA levels 102% and 166% higher than in children with JCA were observed in the sera from children with blood and solid cancers, respectively. The relation LSA/SOD is about fivefold higher in children with cancers. A negative correlation (r = 0.720, P < 0.001) exists between LSA and SOD in sera from children with cancers. No such correlation was established in the group of children with JCA. We suppose that such differentiation disappears in the beginning of neoplastic process during prolonged therapy of autoimmune diseases. From our findings SOD and LSA appear to be putative markers of malignant disease with potential usefulness not only in JCA but also in other conditions associated with an increased risk of neoplastic development.

Adolescent↗
PubMed1993

Lactoferrin binding to human platelets.

1. Platelets bind specifically lactoferrin. 2. The lactoferrin binding to the platelets depends on the concentration of labelled lactoferrin, the number of platelets, the time of incubation and pH. 3. The binding was characterized by two types of binding site: one with high affinity and low capacity, and another with low affinity and high capacity (respectively Kaff1 = 13.6 x 10(9) l/mol and about 40 binding sites, and Kaff2 = 1.23 x 10(9) l/mol and about 135 binding sites per platelet). 4. Both human transferrin and bovine lactoferrin compete with human lactoferrin for the receptors. 5. The presence of lactoferrin receptors on the platelet membrane surface is connected most probably with the effect(s) on the cell function(s) of these cells.

Binding Sites↗