Temperature-Induced Restructuring of Mycolic Acid Bilayers Modeling the Outer Membrane: A Molecular Dynamics Study.

The emergence of new drug-resistant strains of the tuberculosis pathogen (Mtb) is a new challenge for modern medicine. Its resistance capacity is closely related to the properties of the outer membrane of the Mtb cell wall, which is a bilayer membrane formed by mycolic acids (MAs) and their derivatives. To date, the molecular mechanisms of the response of the Mtb outer membrane to external factors and, in particular, elevated temperatures have not been sufficiently studied.

Free Energy Barriers for Passive Drug Transport through the Outer Membrane: A Molecular Dynamics Study.

The emergence of multi-drug-resistant tuberculosis strains poses a significant challenge to modern medicine. The development of new antituberculosis drugs is hindered by the low permeability of many active compounds through the extremely strong bacterial cell wall of mycobacteria. In order to estimate the ability of potential antimycobacterial agents to diffuse through the outer mycolate membrane, the free energy profiles, the corresponding activation barriers, and possible permeability modes of passive transport for a series of known antibiotics, modern antituberculosis drugs, and prospective active drug-like molecules were determined using molecular dynamics simulations with the all-atom force field and potential of mean-force calculations.

Conformational Dynamics and Stability of Bilayers Formed by Mycolic Acids from the Outer Membrane.

Bilayers of mycolic acids (MAs) form the outer membrane of that has high strength and extremely low permeability for external molecules (including antibiotics). For the first time, we were able to study them using the all-atom long-term molecular dynamic simulations (from 300 ns up to 1.2 μs) in order to investigate the conformational changes and most favorable structures of the mycobacterial membranes.

Structure and Phylogeny of the Curly Birch Chloroplast Genome.

Curly birch [ var. (Merckl.) Hämet-Ahti] is a relatively rare variety of silver birch ( Roth) that occurs mainly in Northern Europe and northwest part of Russia (Karelia).

Efficient killing of tumor cells by CAR-T cells requires greater number of engaged CARs than TCRs.

Although CAR-T cells are widely used to treat cancer, efficiency of CAR-T cell cytolytic responses has not been carefully examined. We engineered CAR specific for HMW-MAA (high-molecular-weight melanoma-associated antigen) and evaluated potency of CD8+ CAR-T cells to release cytolytic granules and to kill tissue-derived melanoma cells, which express different levels of HMW-MAA. CAR-T cells efficiently killed melanoma cells expressing high level of HMW-MAA, but not melanoma cells with lower levels of HMW-MAA.

How Many Isomers Do Metallic Clusters Have? Case of Magnesium Clusters of up to 55 Atoms.

About 9000 structures of magnesium clusters Mg ( = 2-13) generated via different methods were optimized at the DFT levels in order to estimate the number of all possible stable structures that can exist for the given cluster size (∼820,000 PES points were explored in total). It was found that the number of possible cluster isomers quickly grows with a number of atoms ; however, it is significantly lower than the number of possible nonisomorphic graph structures, which can be drawn for the given At the DFT potential energy surface, we found only 543 local minima corresponding to the isomers of Mg-Mg. The number of isomers obtained in the DFT optimizations grows with approximately as , whereas the values extrapolated to the infinite generation process grow as .

The Buspirone-dependent Abdominal Pain Transmission Within the Nucleus Tractus Solitarius in the Rat.

Buspirone, a partial agonist of the 5-HTR, due to potential antinociceptive properties can be useful for abdominal pain treatment in IBS patients. Pain-related effects of buspirone can be mediated by the 5-HTRs, located within the nucleus tractus solitarius. The 5-HTR involvement in pain transmission within the NTS is unclear.

Supraspinal Mechanisms of Intestinal Hypersensitivity.

Gut inflammation or injury causes intestinal hypersensitivity (IHS) and hyperalgesia, which can persist after the initiating pathology resolves, are often referred to somatic regions and exacerbated by psychological stress, anxiety or depression, suggesting the involvement of both the spinal cord and the brain. The supraspinal mechanisms of IHS remain to be fully elucidated, however, over the last decades the series of intestinal pathology-associated neuroplastic changes in the brain has been revealed, being potentially responsible for the phenomenon. This paper reviews current clinical and experimental data, including the authors' own findings, on these functional, structural, and neurochemical/molecular changes within cortical, subcortical and brainstem regions processing and modulating sensory signals from the gut.

Molecular Dynamics of Combustion Reactions in Supercritical Carbon Dioxide. Part 5: Computational Study of Ethane Dissociation and Recombination Reactions CH ⇌ CH + CH.

Fossil fuel oxy-combustion is an emerging technology where the habitual nitrogen diluent is replaced by high-pressure supercritical CO (sCO), which increases the efficiency of energy conversion. In this study, the chemical kinetics of the combustion reaction CH ⇌ CH + CH in the sCO environment is predicted at 30-1000 atm and 1000-2000 K. We adopt a multiscale approach, where the reactive complex is treated quantum mechanically in rigid rotor/harmonic oscillator approximation, while environment effects at different densities are taken into account by the potential of mean force, produced with classical molecular dynamics (MD).

Mouse Model for Assessing the Subchronic Toxicity of Organophosphate Pesticides.

The development of antidotes to organophosphate poisons is an important aspect of modern pharmacology. Recombinant acetylcholinesterase and butyrylcholinesterase are effective DNA-encoded acceptors of organophosphate poisons and, in particular, pesticides. Here, we present the results of a study on the effectiveness of recombinant butyrylcholinesterase (BChE) in modeling organophosphate poisoning caused by oral administration of paraoxon at a dose of 2 mg / kg.

Molecular dynamics of combustion reactions in supercritical carbon dioxide. Part 4: boxed MD study of formyl radical dissociation and recombination.

Fossil fuel oxy-combustion is an emergent technology where habitual nitrogen diluent is replaced by high pressure (supercritical) carbon dioxide. The supercritical state of CO increases the efficiency of the energy conversion and the absence of nitrogen from the reaction mixture reduces pollution by NO. However, the effects of a supercritical environment on elementary reactions kinetics are not well understood at present.

QM/MM Description of Newly Selected Catalytic Bioscavengers Against Organophosphorus Compounds Revealed Reactivation Stimulus Mediated by Histidine Residue in the Acyl-Binding Loop.

Butyrylcholinesterase (BChE) is considered as an efficient stoichiometric antidote against organophosphorus (OP) poisons. Recently we utilized combination of calculations and ultrahigh-throughput screening (uHTS) to select BChE variants capable of catalytic destruction of OP pesticide paraoxon. The purpose of this study was to elucidate the molecular mechanism underlying enzymatic hydrolysis of paraoxon by BChE variants using hybrid quantum mechanical/molecular mechanical (QM/MM) calculations.

The central effects of buspirone on abdominal pain in rats.

Background: Buspirone, a partial agonist of the 5-HT receptor (5-HT R), owing to potential antinociceptive properties may be useful in treatment of abdominal pain in IBS patients. The pain-related effects of buspirone are mediated via the 5-HT Rs, specifically located within the ventrolateral medulla (VLM). The most animal studies of the 5-HT R involvement in pain control have been carried out with somatic behavioral tests.

Colitis-induced alterations in response properties of visceral nociceptive neurons in the rat caudal medulla oblongata and their modulation by 5-HT3 receptor blockade.

There is considerable clinical and experimental evidence that intestinal inflammation is associated with altered visceral nociceptive processing in the spinal cord and brain, but the underlying neuronal mechanisms, especially acting at the supraspinal level, remain unclear. Considering that the caudal ventrolateral medulla (CVLM) and the nucleus tractus solitarius (NTS) are the first sites for supraspinal processing of visceral pain signals, in the present study we evaluated the experimental colitis-induced changes in response properties of CVLM and NTS medullary neurons to noxious colorectal distension (CRD) in urethane-anesthetized adult male Wistar rats. To determine if gut inflammation alters the 5-HT receptor-dependent modulation of visceral pain-related CVLM and NTS cells, we examined the effects of intravenously administered selective 5-HT antagonist granisetron on ongoing and CRD-evoked activity of CVLM and NTS neurons in healthy control and colitic animals.

Molecular Dynamics Study of Combustion Reactions in Supercritical Environment. Part 3: Boxed MD Study of CH + HO → CHO + OH Reaction Kinetics.

The kinetics of reaction CH + HO → CHO + OH in supercritical carbon dioxide media at pressures from 0.3 to 1000 atm in the temperature range (600-1600) K was studied using boxed molecular dynamics simulations at QM/MM theory level with periodical boundary conditions. The mechanism of this process includes two consecutive steps: formation and decomposition of CHOOH intermediate.

Molecular Dynamics Study of Combustion Reactions in a Supercritical Environment. Part 2: Boxed MD Study of CO + OH → CO + H Reaction Kinetics.

Oxy-fuel combustion technology holds a great promise in both increasing the efficiency of the energy conversion and reducing environmental impact. However, effects of the higher pressures and replacement of the nitrogen with carbon dioxide diluent are not well understood at present. The title reaction is one of the most important processes in combustion.

Blockade of 5-HT3 receptors with granisetron does not affect trigeminothalamic nociceptive transmission in rats: Implication for migraine.

One way to expand the existing range of anti-migraine drugs seems to be the search for pharmacological agents with anti-cephalalgic properties among medicines approved for clinical indications other than migraine. Numerous experimental and clinical data imply that selective serotonin 5-HT3 receptor antagonists can be considered as potential anti-migraine agents. Therefore, the objective of our work was to examine the impact of selective 5-HT3 receptor blockade with granisetron on migraine-related nociceptive transmission within the spinal trigeminal nucleus (STN) and the ventroposteromedial nucleus of the thalamus (VPM).

Antinociceptive effect of the agonist of 5-HT1A receptors buspirone in the model of abdominal pain in dogs.

We have demonstrated that activation of 5-HT1A receptors with buspirone promotes visceral analgesia in awake dogs. The administration of 0.035 mg/kg (i.

Inhibitory effect of high-frequency greater occipital nerve electrical stimulation on trigeminovascular nociceptive processing in rats.

Electrical stimulation of the greater occipital nerve (GON) has recently shown promise as an effective non-pharmacological prophylactic therapy for drug-resistant chronic primary headaches, but the neurobiological mechanisms underlying its anticephalgic action are not elucidated. Considering that the spinal trigeminal nucleus (STN) is a key segmental structure playing a prominent role in pathophysiology of headaches, in the present study we evaluated the effects of GON electrical stimulation on ongoing and evoked firing of the dura-sensitive STN neurons. The experiments were carried out on urethane/chloralose-anesthetized, paralyzed and artificially ventilated male Wistar rats.

[EFFECTS OF 5-HT3-RECEPTOR BLOCKADE ON VISCERAL NOCICEPTIVE NEURONS IN THE VENTROLATERAL RETICULAR FIELD OF THE RAT MEDULLA OBLONGATA].

The caudal ventrolateral medullary reticular formation is the first supraspinal level processing visce- ral nociceptive signals. In experiments on rats reactions of neurons of this zone to nociceptive stimulation of large intestine were examined and effects of selective blockade of 5-HT3-receptors on these reactions were assessed. According to the character or responses to nociceptive colorectal stimulation (CRS) the re- corded medullary cells were divided into three groups - excitated, inhibited and indifferent.

Effects of Millimeter-Wave Electromagnetic Radiation on the Experimental Model of Migraine.

Effects of millimeter-wave electromagnetic radiation (40 GHz frequency, 0.01 mW power) on the spontaneous fi ring of convergent neurons of the spinal trigeminal nucleus and their responses to electrical stimulation of the dura mater were studied in neurophysiological experiments on rats. Irradiation of the area of cutaneous receptive fields of spinal trigeminal nucleus reversibly inhibited both spontaneous discharges and activity induced by electrical stimulation of the dura mater.

[Microbiological aspects of zirconia orthopedic structures].

The article gives a detailed analysis of oral cavity microbiological aspects of 23 patients before and after prosthetic treatment with zirconia structures. Microbiocenoses of oral cavity in patients with defects of the dentition can be described as disbiotic. It was found that the incidence of lactobacilli and bifidobacteria was increased and frequency of occurrence of pathogens, including Staphylococcus aureus, was decreased under the influence of temporary plastic prosthesis as an intermediate step prosthetics.

The inhibitory effect of granisetron on ventrolateral medulla neuron responses to colorectal distension in rats.

Irritable bowel syndrome (IBS) is one of the most widespread functional gastrointestinal disorders characterized by abdominal pain. A key pathophysiological mechanism of abdominal pain is associated with disturbances of serotonergic transmission in feedback control loops of endogenous pain modulation in which the ventrolateral medulla (VLM) plays an important role. The receptors to serotonin (5-HT), and particularly the serotonin 3 (5-HT3) receptors have been extensively used as a potential target for abdominal pain treatment of IBS patients due to antinociceptive features of the 5-HT3 receptor antagonists.

Intravenous dextromethorphan/quinidine inhibits activity of dura-sensitive spinal trigeminal neurons in rats.

Background: Migraine is a chronic neurological disorder characterized by episodes of throbbing headaches. Practically all medications currently used in migraine prophylaxis have a number of substantial disadvantages and use limitations. Therefore, the further search for principally new prophylactic antimigraine agents remains an important task.