44 research outputs found
Molecular gyroscopes and biological effects of weak ELF magnetic fields
Extremely-low-frequency magnetic fields are known to affect biological
systems. In many cases, biological effects display `windows' in biologically
effective parameters of the magnetic fields: most dramatic is the fact that
relatively intense magnetic fields sometimes do not cause appreciable effect,
while smaller fields of the order of 10--100 T do. Linear resonant
physical processes do not explain frequency windows in this case. Amplitude
window phenomena suggest a nonlinear physical mechanism. Such a nonlinear
mechanism has been proposed recently to explain those `windows'. It considers
quantum-interference effects on protein-bound substrate ions. Magnetic fields
cause an interference of ion quantum states and change the probability of
ion-protein dissociation. This ion-interference mechanism predicts specific
magnetic-field frequency and amplitude windows within which biological effects
occur. It agrees with a lot of experiments. However, according to the
mechanism, the lifetime of ion quantum states within a protein
cavity should be of unrealistic value, more than 0.01 s for frequency band
10--100 Hz. In this paper, a biophysical mechanism has been proposed that (i)
retains the attractive features of the ion interference mechanism and (ii) uses
the principles of gyroscopic motion and removes the necessity to postulate
large lifetimes. The mechanism considers dynamics of the density matrix of the
molecular groups, which are attached to the walls of protein cavities by two
covalent bonds, i.e., molecular gyroscopes. Numerical computations have shown
almost free rotations of the molecular gyros. The relaxation time due to van
der Waals forces was about 0.01 s for the cavity size of 28 angstr\"{o}ms.Comment: 10 pages, 7 figure
Stochastic Dynamics of Magnetosomes in Cytoskeleton
Rotations of microscopic magnetic particles, magnetosomes, embedded into the
cytoskeleton and subjected to the influence of an ac magnetic field and thermal
noise are considered. Magnetosome dynamics is shown to comply with the
conditions of the stochastic resonance under not-too-tight constraints on the
character of the particle's fastening. The excursion of regular rotations
attains the value of order of radian that facilitates explaining the biological
effects of low-frequency weak magnetic fields and geomagnetic fluctuations.
Such 1-rad rotations are effectively controlled by slow magnetic field
variations of the order of 200 nT.Comment: LaTeX2e, 7 pages with 3 figure
New mechanism of solution of the -problem in magnetobiology
The effect of ultralow-frequency or static magnetic and electric fields on
biological processes is of huge interest for researchers due to the resonant
change of the intensity of biochemical reactions although the energy in such
fields is small. A simplified model to study the effect of the weak magnetic
and electrical fields on fluctuation of the random ionic currents in blood and
to solve the problem in magnetobiology is suggested. The analytic
expression for the kinetic energy of the molecules dissolved in certain liquid
media is obtained. The values of the magnetic field leading to resonant effects
in capillaries are estimated. The numerical estimates showed that the resonant
values of the energy of molecular in the capillaries and aorta are different:
under identical conditions a molecule of the aorta gets times less
energy than the molecules in blood capillaries. So the capillaries are very
sensitive to the resonant effect, with an approach to the resonant value of the
magnetic field strength, the average energy of the molecule localized in the
capillary is increased by several orders of magnitude as compared to its
thermal energy, this value of the energy is sufficient for the deterioration of
the chemical bonds.Comment: 10 pages, Accepted to the Journal Central European Journal of Physic
Interference mechanism for some biological effects of pulsed magnetic fields
Abstract Ćœ . A mechanism that describes effects of a pulsed magnetic field PMF of ELF range on some biological systems is presented. This mechanism, based on earlier proposed ion interference mechanism, links the dissociation probability of ion-protein complexes to parameters of PMF. Quantum dynamics of ion is studied in the case of PMF combined in line with a static magnetic field. A rule that enables us to reach a maximal biological response on PMF is found. The formula is derived for the first time for biological efficacy of a PMF. Calculations were made for Ca-and Mg-protein complexes. The results show a good consistency with known experimental data. q 1998 Elsevier Science S.A
Magnetobiology: the kT paradox and possible solutions
The article discusses the so-called 'kT problem &apos