It has been generally accepted that heterochromatin is represented by a regular, dense and closed structure, while euchromatin is open and sparse. Recent evidence indicates that chromatin is comprised of irregular nucleosome clutches compacted within the nucleus. Transcriptional events transform the chromatin architecture, resulting in appearance of 100-300 nm nucleosomal aggregates.
View Article and Find Full Text PDFBiochim Biophys Acta Gen Subj
April 2024
Background: The gene expression differs in the nuclei of normal and malignant mammalian cells, and transcription is a critical initial step, which defines the difference. The mechanical properties of transcriptionally active chromatin are still poorly understood. Recently we have probed transcriptionally active chromatin of the nuclei subjected to mechanical stress, by Atomic Force Microscopy (AFM) [1].
View Article and Find Full Text PDFThe technique of atomic force microscopy (AFM) bending tests of a suspended nano-object (scroll, tube, rod) makes it possible to calculate the Young's modulus of the material it is made of based on experimental data. However, the calculation results involve a large error due to uncertain conditions (console or bridge) of fixing the test object. One of the ways to reduce this error is based on the theoretical consideration of consoles or bridges as beams with one or two ends resting on Winkler elastic foundations.
View Article and Find Full Text PDFA group of phyllosilicate nanoscrolls conjoins several hydrosilicate layered compounds with a size mismatch between octahedral and tetrahedral sheets. Among them, synthetic MgSiO(OH) chrysotile nanoscrolls (obtained via the hydrothermal method) possess high thermal stability and mechanical properties, making them prospective composite materials fillers. However, accurate determination of these nano-objects with Young's modulus remains challenging.
View Article and Find Full Text PDFBiochim Biophys Acta Gen Subj
December 2022
Background: Nuclear rigidity is traditionally associated with lamina and densely packed heterochromatin. Actively transcribed DNA is thought to be less densely packed. Currently, approaches for direct measurements of the transcriptionally active chromatin rigidity are quite limited.
View Article and Find Full Text PDFAim To study features of coronary damage and incidence of different types of acute coronary syndrome (ACS) in history associated with primary symptomatic hypothyroidism in patients with ischemic heart disease (IHD) and possible associations of replacement hormonal therapy with lipidogram indexes.Material and methods This retrospective study included 344 patients with IHD and functional class I-III stable angina (ССS, 1976). Of them 100 patients had primary symptomatic hypothyroidism and 244 had no hypothyroidism.
View Article and Find Full Text PDFCan J Physiol Pharmacol
November 2020
In the primary sensory neuron, ouabain activates the dual mechanism that modulates the functional activity of Na1.8 channels. Ouabain at endogenous concentrations (EO) triggers two different signaling cascades, in which the Na,K-ATPase/Src complex is the EO target and the signal transducer.
View Article and Find Full Text PDFWe present a study of electronic and magnetic properties of nominal magnetite nanoparticles (NPs) (~6 nm) at high pressure in the presence of silicon pressure medium using x-ray absorption near edge structure (XANES), x-ray magnetic circular dichroism (XMCD) and non-resonant x-ray emission spectroscopy (XES). XANES data show a reduction of Fe charge state, a change in local environment around Fe at tetrahedral sites, and a reduced occupation of Fe 4p orbitals, not seen in previous pressure studies of bulk magnetite. XMCD data show a continuous magnetic moment reduction of ~50% between ambient pressure and 20 GPa, similar to what was observed in previous bulk magnetite studies.
View Article and Find Full Text PDFThis review presents relevant information about development and course of chronic heart failure (CHF) associated with rheumatoid arthritis (RA). One of the most discussed issues is the effect of systemic inflammatory process on prognosis of CHF. The review focused on current evidence for significance of this comorbidity in CHF.
View Article and Find Full Text PDFProbl Sotsialnoi Gig Zdravookhranenniiai Istor Med
April 2018
The article presents the results of analysis of widespread of prevalence of additional medical services and voluntary medical insurance of working population of Russia. The quantitative values were received concerning widespread of disposal to Russian workers of various industries of social benefits on partial and full payment of treatment, degree of participation of workers in programs of voluntary medical insurance. It is demonstrated that besides sectorial characteristics the determinants of widespread of granting additional medical insurance are positioned as individual characteristics of workers and such obstacles as length of service, education, salary of worker, type of residence settlement, harmful and dangerous conditions of labor, type of property of enterprise (public/non-public).
View Article and Find Full Text PDFThe Young's modulus of 10-12-day-old chick embryos' sensory neurons cultivated in dissociated cell culture was measured using a PeakForce Quantitative Nanomechanical Mapping atomic force microscopy. The native cells were tested in control experiments and after application of ouabain. At low "endogenous" concentration of 10⁻¹⁰ M, ouabain tended to increase the rigidity of sensory neurons.
View Article and Find Full Text PDFScanning near-field optical microscopy was applied to study, with sub-wavelength spatial resolution, the near- and the far-field distributions of propagating modes from a high-power laser diode. Simple modeling was also performed and compared with experimental results. The simulated distributions were consistent with the experiment and permitted clarification of the configuration of the transverse modes of the laser.
View Article and Find Full Text PDFProbl Sotsialnoi Gig Zdravookhranenniiai Istor Med
May 2014
The article presents the results of study of character of consumption of alcohol products by representatives of different professional groups. The research data was obtained from representative sampling of working population of Russia. On the basis of probit-modeling estimates of possibility of even if once consumption of alcohol were calculated.
View Article and Find Full Text PDFConductive-probe atomic force microscopy (CP-AFM) measurements reveal the existence of a conductive channel at the interface between p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar conductance measurements that show a large interface conductance. It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n) a-Si:H/(p) c-Si heterojunctions.
View Article and Find Full Text PDFPresent-day multimedia strongly rely on rewritable phase-change optical memories. We demonstrate that, different from the current consensus, Ge(2)Sb(2)Te(5), the material of choice in DVD-RAM, does not possess the rocksalt structure but more likely consists of well-defined rigid building blocks that are randomly oriented in space consistent with cubic symmetry. Laser-induced amorphization results in drastic shortening of covalent bonds and a decrease in the mean-square relative displacement, demonstrating a substantial increase in the degree of short-range ordering, in sharp contrast to the amorphization of typical covalently bonded solids.
View Article and Find Full Text PDFA major goal of theoretical simulations of X-ray absorption fine structure (XAFS) is to provide calculations for the interpretation and analysis of experimental data in terms of geometrical and electronic information. The extended region or EXAFS (50-2000 eV above an absorption edge) contains geometric information about the pair distribution function, i.e.
View Article and Find Full Text PDFJ Synchrotron Radiat
January 2003
There has been dramatic progress over the past decade both in theory and in ab initio calculations of X-ray absorption fine structure. Significant progress has also been made in understanding X-ray absorption near-edge structure (XANES). This contribution briefly reviews the developments in this field leading up to the current state.
View Article and Find Full Text PDFThe mass absorption coefficients of tungsten and tantalum were measured with soft x-ray photons from 1450 eV to 2350 eV using an undulator source. This region includes the M3, M4, and M5 absorption edges. X-ray absorption fine structure was calculated within a real-space multiple scattering formalism; the predicted structure was observed for tungsten and to a lesser degree tantalum as well.
View Article and Find Full Text PDFThe interpretation of X-ray absorption spectra in terms of electronic structure has long been of interest. Hole counts derived from such spectra are often interpreted in terms of free-atom occupation numbers or Mülliken counts. It is shown here, however, that renormalized-atom (RA) and cellular counts are better choices to characterize the configuration of occupied electron states in molecules and condensed matter.
View Article and Find Full Text PDFJ Synchrotron Radiat
March 2001
There has been dramatic progress over the past decade both in theory and in ab initio calculations of X-ray absorption fine structure (XAFS). Rapid progress is now being made in understanding X-ray absorption near-edge structure (XANES). This presentation reviews the developments in this field by many groups leading up to the current state of the art.
View Article and Find Full Text PDFThe sensitivity of Pt L-edge XANES to local geometric and electronic structure in various Pt(n) clusters is investigated using the ab initio self-consistent FEFF8 code. Calculations based on FEFF8 are found to be in good agreement with experiment. For pure Pt clusters the XANES can distinguish between 2- and 3-dimensional clusters.
View Article and Find Full Text PDFPhys Rev Lett
February 2001
Hydrogen adsorption on Pt(6)H(n) clusters leads to striking changes in the Pt L(2,3) x-ray absorption spectra. These effects are interpreted using a self-consistent real space Green's function approach. Calculations show that they are due largely to changes in the atomic background contribution to x-ray absorption (i.
View Article and Find Full Text PDFWe report the first quantitative measurement of extended x-ray absorption fine structure (EXAFS) from hydrogen atoms. A single oscillation is observed from gaseous water consistent with the location of the covalently bonded hydrogen in H 2O. The experimental phase and amplitude of the oscillation are in excellent agreement with curved wave multiple scattering calculations for isolated water molecules.
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