382 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
Use of branched-chain amino acids for reducing exercise-caused skeletal muscle damage
Introduction: Skeletal muscles damage (direct and vicarious) slows down the recovery processes in patients with injuries of the musculoskeletal system. It occurs in the early postoperative period as well. An increase in the rigidity of the skeletal muscle extracellular matrix can reduce pain, tissue swelling, and accelerate the recovery of contractility.Objective: The analyses of the effect of branched-chain amino acids (BCAAs) intake on the expression of IGF1 genes, type 1, 3 and 5 collagen, which are crucial in the composition of the skeletal muscle extracellular matrix, as well as on the muscle membrane damage against the background of chronic damage to skeletal muscles.Material and methods: 12 young healthy male subjects, skiers aged 19 (18; 22) received a placebo treatment (maltodextrin, 100 mg/kg body weight/day; n = 6) or a mixture of amino acids (leucine, isoleucine, valine – 50:25:20 mg/kg body weight/day respectively; n = 6). The treatment was received daily against the background of a large amount of aerobic high-intensity training (up to 22 hours per week). Before and after the amino acids intake a biopsy of the musculus vastus lateralis was performed, and venous blood samples were taken during the experiment.Results: The intake of leucine against the background of training led not only to a pronounced increase in the level of IGF1 protein in blood by 1.5 times (which corresponds to the literature data), but also to a trend towards an increase in the expression of IGF1Ea mRNA by 1.8 times in the skeletal muscle, and a decrease in the level of markers of muscle membranes damage – creatine phosphokinase (CPK) activity and myoglobin. In addition, changes in the IGF1-dependent collagen genes expression strongly correlated with changes in IGF1Ea expression, but not with IGF1 protein in blood (pooled group, n = 12). Thus, the intake of leucine as a part of the essential amino acids can reduce damage to skeletal muscles caused by excessive physical activity, lack of physical activity, or direct trauma.Conclusion: A 10-week BCAAs intake by individuals with documented chronic muscle membrane damage caused an increase of basal levels of IGF1 in blood and a trend towards increased IGF1Ea mRNA expression in skeletal muscle, and also caused a modest reduction in damage of skeletal muscle membrane
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
A human CCT5 gene mutation causing distal neuropathy impairs hexadecamer assembly in an archaeal model
Chaperonins mediate protein folding in a cavity formed by multisubunit rings. The human CCT has eight
non-identical subunits and the His147Arg mutation in one subunit, CCT5, causes neuropathy. Knowledge
is scarce on the impact of this and other mutations upon the chaperone’s structure and functions. To make
progress, experimental models must be developed. We used an archaeal mutant homolog and demonstrated
that the His147Arg mutant has impaired oligomeric assembly, ATPase activity, and defective protein
homeostasis functions. These results establish for the first time that a human chaperonin gene defect can be
reproduced and studied at the molecular level with an archaeal homolog. The major advantage of the system,
consisting of rings with eight identical subunits, is that it amplifies the effects of a mutation as compared
with the human counterpart, in which just one subunit per ring is defective. Therefore, the slight deficit of a
non-lethal mutation can be detected and characterized
Optical switching of radical pair conformation enhances magnetic sensitivity
The yield of chemical reactions involving intermediate radical pairs is
influenced by magnetic fields well beyond the levels expected from energy
considerations. This dependence can be traced back to the microscopic dynamics
of electron spins and constitutes the basis of the chemical compass. Here we
propose a new experimental approach based on molecular photoswitches to achieve
additional control on the chemical reaction and to allow short-time resolution
of the spin dynamics. Our proposal enables experiments to test some of the
standard assumptions of the radical pair model and improves the sensitivity of
chemical magnetometers by two orders of magnitude
Study of the system in the mass range up to 1200 MeV
The reaction has been studied with GAMS-2000
spectrometer in the secondary 38 GeV/c -beam of the IHEP U-70
accelerator. Partial wave analysis of the reaction has been performed in the
mass range up to 1200 MeV. The -meson is seen as a sharp
peak in S-wave. The -dependence of production cross section has
been studied. Dominant production of the at a small transfer
momentum confirms the hypothesis of Achasov and Shestakov about significant
contribution of the exchange () in the mechanism
of meson production in -channel of the reaction.Comment: 4 pages, 3 figures, talk given at HADRON'9
Disulfide Bridges Remain Intact while Native Insulin Converts into Amyloid Fibrils
Amyloid fibrils are β-sheet-rich protein aggregates commonly found in the organs and tissues of patients with various amyloid-associated diseases. Understanding the structural organization of amyloid fibrils can be beneficial for the search of drugs to successfully treat diseases associated with protein misfolding. The structure of insulin fibrils was characterized by deep ultraviolet resonance Raman (DUVRR) and Nuclear Magnetic Resonance (NMR) spectroscopy combined with hydrogen-deuterium exchange. The compositions of the fibril core and unordered parts were determined at single amino acid residue resolution. All three disulfide bonds of native insulin remained intact during the aggregation process, withstanding scrambling. Three out of four tyrosine residues were packed into the fibril core, and another aromatic amino acid, phenylalanine, was located in the unordered parts of insulin fibrils. In addition, using all-atom MD simulations, the disulfide bonds were confirmed to remain intact in the insulin dimer, which mimics the fibrillar form of insulin
Search for the decay
We performed a search for the decay with the
E391a detector at KEK. In the data accumulated in 2005, no event was observed
in the signal region. Based on the assumption of
proceeding via parity-violation, we obtained the single event sensitivity to be
, and set an upper limit on the branching ratio to
be at the 90% confidence level. This is a factor of 3.2
improvement compared to the previous results. The results of proceeding via parity-conservation were also presented in this paper
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