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Biomedical subjects

L Zolla

Publications and source records attributed to L Zolla.

10 recordsLinked to original sources
PubMed1992

Entrapment of protein protease inhibitors in red blood cells.

Aprotinin and alpha 1-proteinase inhibitor have been encapsulated in human red blood cells (RBC) by a dialysis technique that involves transient hypotonic haemolysis followed by isotonic resealing. Both protease inhibitors can be encapsulated to a considerable extent. These molecules are released only by haemolysis of the cells and that excludes the possibility of using loaded erythrocytes for a slow release of the inhibitor(s) in the blood stream. However, the stability of the two inhibitors, the evidence for the binding of aprotinin to RBC components, and the results showing inhibition of endogenous proteolytic activity indicate that the inhibitors may be valuable in blocking, at least partially, undesired intraerythrocytic proteolytic reactions.

Aprotinin↗
PubMed1991

Red blood cells as carriers for delivering of proteins.

The potential use of red blood cells as a carrier system for transport and delivery of pharmacological substances is well documented. Various methods have been attempted for encapsulation of drugs; in this review we evaluate critically all the procedures illustrating their advantages and disadvantages. Moreover, we present kinetic studies of protein encapsulation by moderate hypotonic dialysis, which allows entrapment of molecules with MW less than 50,000 Da with negligible stress of the erythrocyte membrane. Furthermore data reveal that the resealing procedure commonly used is insufficient to completely seal pores of loaded erythrocytes, allowing entrapped proteins with MW less than 12-14,000 Da to escape. However, only 20-30% of the entrapped material is released, depending on the final cytocrit, while the remaining is associated to the inner membrane or to cytosolic components. Although the method of hypotonic dialysis is known to be the one that minimally affects the biophysical and immunological properties of the red blood cell membrane, the interaction of encapsulated material with cell costituents would need to be further assessed when considering red cells as macromolecular carriers.

Cell Membrane Permeability↗
PubMed1990

Encapsulation of proteins into human erythrocytes: a kinetic investigation.

Moderate osmotic shocks of human erythrocytes by hypotonic dialysis (0.06 mosmol/kg) induce cell swelling and formation of pores, without causing apparent lysis. Using 125I-labeled macromolecules of different molecular weight and net charge, we followed the kinetics and efficiency of their encapsulation into erythrocytes. After a 20-30 min period of cell dialysis, macromolecules of up to 50 kDa begin diffusing into the swollen cells by a process which can be described by a first-order two-compartment kinetics. Adsorption to the external cell surface was insignificant, while adsorption to the inner membrane surface was substantial (15-20%) only for positively charged proteins, at physiological pH. After resealing, pores of a 12-14 kDa cut-off might remain open allowing some release of entrapped material (20-30%), depending on the final cytocrit, while the remaining might be associated with inner membrane or cytosolic components. Although the method of hypotonic dialysis is known to affect minimally the biophysical and immunological properties of red blood cell membranes, the interaction of encapsulated material with cell constituents would need to be further assessed when considering red cells as macromolecular carriers.

Cell Membrane Permeability↗
PubMed1977

The effect of macromolecular polyanions on the functional properties of human hemoglobin.

The binding of dextran sulphate and heparin to human hemoglobin and their effect on the properties of gas transport have been investigated. Both dextran sulphate and heparin are strongly bound by oxy-hemoglobin as well as deoxyhemoglobin and the stoichiometry of the binding (polyanion/tetrameric hemoglobin) is less than unity; sedimentation analysis gives indication for the existence of octomers. The oxygen affinity of hemoglobin is decreased, to the same extent, by both dextran sulphate and heparin. This effect is pH-dependent. In addition the polyanions affect the position and the magnitude of the Bohr effect. In the presence of dextran sulphate the recombination of hemoglobin with carbon monoxide after flash photolysis is biphasic and the fraction of quickly reacting material increases with dilution of the protein.

Dextrans↗