On the problem of field-gradient NMR measurements of intracrystalline diffusion in small crystallites--water in NaA zeolites as an example.

Necessary conditions for measuring intracrystalline diffusion in small crystal size systems via field-gradient NMR are discussed. As an illustrative case self-diffusion coefficients of water adsorbed in NaA zeolites (average crystal diameter about 1 microm) have been measured by 1H-NMR stimulated echoes in static magnetic field gradients of up to 180 T/m in the temperature range of 254-344 K. Obtaining intracrystalline diffusion coefficients necessitates a sufficiently high spatial resolution only provided by such large field gradients.

In vitro effects of ozone on human erythrocyte membranes: an EPR study.

The effects of ozone at different concentrations (10, 30, 45 g/m3) on fluidity and thermotropic properties of erythrocyte membranes were investigated by EPR using two spin probes: 5-doxylstearic acid (5-DSA) and 16-doxylstearic acid (16-DSA). The effect of ozone on the erythrocyte membrane fluidity was a dose-dependent process. The ozone at concentration of 10 g/m3 caused rigidization of the membrane while at concentration of 45 g/m3 increased fluidity both on the surface and in the deeper hydrocarbon region of the membrane.

Relaxation of water protons in highly concentrated aqueous protein systems studied by 1H NMR spectroscopy.

Concentrated Aqueous Protein Systems, Proton Relaxation Times, Slow Chemical Exchange In this paper we present proton spin-lattice (T1) and spin-spin (T2) relaxation times measured vs. concentration, temperature, pulse interval (tauCPMG) as well as 1H NMR spectral measurements in a wide range of concentrations of bovine serum albumin (BSA) solutions. The anomalous relaxation behaviour of the water protons, similar to that observed in mammalian lenses, was found in the two most concentrated solutions (44% and 46%).

Erythrocyte membrane fluidity changes in psoriasis: an EPR study.

The aim of the study was to find the cause of membrane fluidity decrease in psoriasis, observed by other authors, in different types of cells and its clinical consequences. To this end, we have examined the influence of different clinical and biochemical factors on erythrocyte membrane fluidity changes in psoriatic patients. Membrane fluidity was studied by the electron paramagnetic resonance spin-labeling method.

In vivo and in vitro influence of etretinate on erythrocyte membrane fluidity.

The molecular mechanisms underlying the action of synthetic retinoids have been studied intensively, but they are not fully understood yet. It is well known that retinoids exert their effects on gene expression via the retinoic acid receptor. Some observations suggest that the main aromatic retinoid etretinate (Tigason) exerts its therapeutic effect in psoriasis also through an action on the cell membrane.