Electrical conductivity of human erythrocytes infected with Plasmodium falciparum and its modification following quinine therapy.
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Animals↗
Biomedical subjects
A Bonincontro
Publications and source records attributed to A Bonincontro.
Conductivity of normal and pathological human erythrocytes (homozygous beta-thalassemia) at radiowave frequencies.
The conductivity of normal and homozygous beta-thalassemic erythrocyte suspensions has been measured over the frequency range from 5 KHz to 100 MHz in the temperature interval from 5 to 45 degrees C. The electrical parameters of the membrane, i.e., the capacitance CM and the conductance GM per unit surface have been calculated from an expression given by Hanai for the conductivity of a suspension of ellipsoidal particles covered with a shell. Some interesting differences between the normal and pathological state are evidentiated.
Electric Conductivity↗
Effect of extracellular alkali metal salts on the electric parameters of human erythrocytes in normal and pathological conditions (homozygous beta-thalassemia).
The conductivity of human erythrocyte cells dispersed in various uni-univalent electrolyte solutions (NaCl, KCl, LiCl, CsCl; 0.15 M) have been measured in the frequency range from 10 KHz to 100 MHz at five temperatures between 5 and 45 degrees C. The results were analyzed in the light of the theory of conductivity polarization of a suspension of ellipsoidal particles-covered with two confocal shells. Differences in the electrical parameters of the membrane between normal and homozygous beta-thalassemic cells have been evidentiated.
Electric Conductivity↗
Dielectric properties of ribosomal core particles lacking a select population of proteins.
In this communication we present a comparative investigation of the dielectric properties of native E. coli 70S and ribosomal cores obtained by LiCl treatment. Previous data obtained in our laboratory showed that ribosomes exhibit two different dielectric dispersions. We show that elimination of some select proteins modifies only the first one and therefore the overall dielectric properties of the ribosome result altered. Ribosomal RNA and proteins remaining in the core particle are mainly responsible for the second dielectric dispersion. Our experimental approach allows an estimation of the size of RNA traits exposed to solvent both in native ribosomes and in core particles where a higher portion of rRNA interacts with the external environment. Furthermore our results are consistent with the idea that proteins remaining after high salt treatment are necessary and sufficient for the maintenance of the basic structural properties of the ribosome.
Electricity↗
Instability of three-dimensional structures in ribosomal cores evidenced by microcalorimetric studies.
In this paper we show a microcalorimetric investigation carried out on the so-called cores, i.e. ribosomes deprived of select proteins by LiCl treatment. Thermal degradation of native ribosomes gives rise to two thermal transitions occurring at different temperatures. In the cores the high temperature peak persists even after treatment at very high ion strength (2 M LiCl). This strongly suggests the existence of a very stable structure that was previously observed also in particles treated with agents that hydrolyze the RNA moiety. The low temperature peak gradually but dramatically decreases even though it never disappears completely. This indicates that the treatment to obtain ribosomal cores does not cause complete unfolding of the particle but only the destabilization of a structural three-dimensional domain present in native ribosomes. These data are discussed in the light of previous results obtained by dielectric spectroscopy and microcalorimetric studies on ribosomal particles.
Calorimetry, Differential Scanning↗