Limits of diagnostic accuracy of anti-hepatitis C virus antibodies detection by ELISA and immunoblot assay.

When human sera samples are tested for anti-hepatitis C virus (HCV) antibodies using different ELISA kits as well as immunoblot assay kits discrepant results often occur. As a result the diagnostics of HCV infection in such sera remains unclear. The purpose of this investigation is to define the limits of HCV serodiagnostics.

[The permeability of rat erythrocyte membranes for sodium and potassium ions during exposure to pulsed electromagnetic field under head-down-tilt hypokinesia].

The effect of a low-frequency (1 and 10 Hz) pulse electromagnetic field (PEMF) on permeability of erythrocyte membrane in 47 rats while being exposed to a 14-day head-down tilt (HDT) and in 60 control rats was studied. After exposure to PEMF (20 min, 6-24 mT) the rats were Na(+)-, K(+)-cotransport and Na+,Na(+)-metabolism, Na and K losses as well as specific activity of Na(+)-, K(+)-ATP in the erythrocytes have been measured. An ability of PEMF to inhibit an ATP activity by 20-30% and to increase the rate of ions loss from the cells has been revealed.

Interaction of alkaline metal ions with Ca(2+)-binding sites of Ca(2+)-ATPase of sarcoplasmic reticulum: 23Na-NMR studies.

The analysis of the 23Na-NMR signal shape variations in the presence of vesicles of light sarcoplasmic reticulum (SR) shows the existence of sodium sites on the membranes with Kd values of about 10 mM. Other monovalent cations displace Na+ from SR fragments in a competitive manner according to the row K+ greater than Rb+ greater than Cs+ greater than Li+. Calcium ions also reduce Na+ binding, the Na+ desorption curve being of a two-stage nature, which, as suggested, indicates the existence of two types of Ca(2+)-sensitive Na+ binding sites (I and II).

[Interaction of alkali metal ions with Ca2+-binding center of Ca2+- ATPase of the sarcoplasmic reticulum in skeletal muscles].

Sodium ion interaction with sarcoplasmic reticulum (SR) membranes leads to considerable alterations of the [23Na]NMR lineshape. Na+ binding to SR in the presence of Ca2+ and H+ is well described by a model which postulates a competitive ion binding to high and low affinity sites of Ca2+-ATPase. The dissociation constant, Kd, for high and low affinity sites is 5 and 10 mM, respectively, for Na+ and (3-5).