Interaction Of Gd3 Research Articles

Benefits and Detriments of Gadolinium from Medical Advances to Health and Ecological Risks.

Gadolinium (Gd)-containing chelates have been established as diagnostics tools. However, extensive use in magnetic resonance imaging has led to increased Gd levels in industrialized parts of the world, adding to natural occurrence and causing environmental and health concerns. A vast amount of data shows that metal may accumulate in the human body and its deposition has been detected in organs such as brain and liver. Moreover, the disease nephrogenic systemic fibrosis has been linked to increased Gd3+ levels. Investigation of Gd3+ effects at the cellular and molecular levels mostly revolves around calcium-dependent proteins, since Gd3+ competes with calcium due to their similar size; other reports focus on interaction of Gd3+ with nucleic acids and carbohydrates. However, little is known about Gd3+ effects on membranes; yet some results suggest that Gd3+ interacts strongly with biologically-relevant lipids (e.g., brain membrane constituents) and causes serious structural changes including enhanced membrane rigidity and propensity for lipid fusion and aggregation at much lower concentrations than other ions, both toxic and essential. This review surveys the impact of the anthropogenic use of Gd emphasizing health risks and discussing debilitating effects of Gd3+ on cell membrane organization that may lead to deleterious health consequences.

Mechanosensitive ion channel inhibitors promote the stiffening of the plasma membrane of mouse sensory neurons.

The mechanosensitivity of cells depends on the lipid-protein interactions of the plasma membrane. Affectations in the lipid region of the plasma membrane affect the transduction of mechanical forces, and any molecule that modifies the biophysical integrity of the lipid bilayer can alter the mechanical activity of the proteins inside the membrane. To understand whether inhibitors of mechanically activated ion channels affect the mechanical properties of the plasma membrane, we evaluated the rigidity of the membrane of sensory neurons of the DRG of mice using a variant of the scanning ion conductance microscopy method, which allows us to calculate the Young's modulus of individual cells before and after the perfusion of different doses of Gd3+, ruthenium red and GsMTx-4. Our results suggest that these molecules compromise the membrane by increasing the Young's modulus value, which indicates that the membrane becomes more rigid; these compounds act through different mechanisms and by a non-specific manner, each one shows a certain preference for specific cell subpopulations, depending on their cell size and their reactivity to isolectin B4. Our results support the idea that the biophysical properties that result from the interactions that arise in the membranes are part of the mechanotransduction process.

Superhyperfine interaction in the trigonal center BaF2: Gd3+ and the lattice distortion analysis in the vicinity of the impurity ion

The constants of the superhyperfine interaction of Gd3+ with the 19F nuclear spins in the first four coordination shells were determined from the ENDOR spectra of a trigonal BaF2: Gd3+ center. These data were used for analysis of the crystalline lattice distortions in the vicinity of the impurity ion. It was found that the largest displacements of fluorine nuclei occurred in the vicinity of the ion compensator and the impurity ion. To calculate the anion positions within the first coordinate shell, whose electron-nuclear interaction with Gd3+ depends considerably on chemical bonds in the Gd3+F8− complex, an empirical model is used for the isotropic constants of the superhyperfine interaction of Gd3+ with fluorine nuclei in cubic centers, with allowance made for the impurity ion polarization.

Interaction of Gd(III) MRI contrast agents with membranes: a review of recent EPR studies.

Rational development of new selective paramagnetic contrast agents (PCAs) requires a detailed understanding of their interactions with biological macromolecules. This report shows how some of these interactions can be studied with electron paramagnetic resonance (EPR) through examples of Gd3+ complexes interactions with model phospholipid membranes. It is shown that the spin label EPR method can be used to detect: (i) presence and possible location of lipophilic contrast agents in the model membranes, (ii) changes and distortions in membrane organization upon interaction with the PCAs, and (iii) changes in the local polarity of the bilayer and its phase behavior due to addition of Gd3+ complexes. This work demonstrates that interaction of Gd3+ complexes with phospholipid bilayers can be observed directly from changes in their continuous wave (CW) EPR spectra obtained at frequencies higher than X-band (9.5 GHz), where signals arising from aqueous and lipid-bound Gd3+ complexes become resolved. Analysis of frequency dependence of the effective g-factors of the EPR signal provides estimates of zero-field splitting (ZFS) parameter for these complexes at physiological conditions and information on how this parameter is affected by interaction with lipids. Multifrequency EPR experiments at high magnetic fields are also useful in providing data on the frequency dispersion of electronic relaxation caused mainly by a modulation of the electron-electron dipolar interaction (ZFS) of these high spin ions.

Electron spin resonance studies at the phase transition in YbInCu4

In the intermetallic compound YbInCu4 the Gd3+-ESR and the static susceptibility were measured in the temperature range 1.5K–300 K, i.e. both below and above the valence phase transition which occurs in this material at Tph≈50 K. The Gd3+ resonance is mainly determined by exchange interaction of Gd3+ ions with fluctuating Yb3+ ions via conduction electrons (RKKY coupling) both below and above this transition. Arguments are presented that at low temperature YbInCu4 is a dense Kondo system (mixed valent state).

On Magnetostriction of Gadolinium Iron Garnets

The temperature dependence of magnetostriction in the gadolinium ferrite having structure of a garnet has been measured within the temperature range from liquid nitrogen up to the Curie point. At temperatures above the compensation point of sublattices, θk, the magnetostriction isotherms are of the same kind as for ferromagnetics (λ∥ and λ⊥ have opposite signs and the λ vs H curves exhibit saturation). In cooling below, θk there is an effect of superposition of large volume magnetostriction of paraprocess on the “ordinary”magnetostriction, which results in the distortion of the magnetostriction isotherms (λ∥ and λ⊥ are of the same sign and without saturation). It is shown that the “ordinary” magnetostriction is caused by the interaction of >Fe3+ ions in sublattices a and d, while the volume magnetostriction of the paraprocess is caused by the interaction of Gd3+ and Fe3+ ions.