force fields
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Recent advances in polarizable force fields have revealed that major reparameterization is necessary when the polarization energy is treated explicitly. This study is focused on the torsional parameters, which are crucial for the accurate description of conformational equilibria in biomolecules. In particular, attention is paid to the influence of polarization on the (i) transferability of dihedral terms between molecules, (ii) transferability between different environments, and (iii) additivity of dihedral energies. To this end, three polarizable force fields based on the induced point dipole model designed for use in AMBER are tested, including two recent ff02 reparameterizations. Attention is paid to the contributions due to short range interactions (1-2, 1-3, and 1-4) within the four atoms defining the dihedral angle. The results show that when short range 1-2 and 1-3 polarization interactions are omitted, as for instance in ff02, the 1-4 polarization contribution is rather small and unlikely to improve the description of the torsional energy. Conversely, when screened 1-2 and 1-3 interactions are included, the polarization contribution is sizeable and shows potential to improve the transferability of parameters between different molecules and environments as well as the additivity of dihedral terms. However, to reproduce intramolecular polarization effects accurately, further fine-tuning of the short range damping of polarization is necessary.
Modelling of carbohydrate conformations is a challenging task for force field developers. Three carbohydrate force fields, namely GLYCAM06, GROMOS 45a4 and OPLS were evaluated. Free energies of different ring conformations of beta-D-glucopyranose were calculated using metadynamics in vacuum as well as in explicitly modelled water. All three force fields model the (4)C(1) conformation as the most stable by at least 6kJ/mol, as compared to other conformations. Interconversion from the (4)C(1) to any other conformation is associated with a barrier of no lower than 26kJ/mol. The free energy surface calculated in the GLYCAM06 force field is in remarkably good agreement with the recent Car-Parrinello metadynamics study. The effect of a water environment is relatively low and analogous in all tested force fields. Namely, the presence of water stabilizes the upper-left ((3,O)B) versus bottom-right (B(3,O)) area of Stoddard's plot, relative to the situation in vacuum. Comparison of free and potential surfaces is also provided for vacuum calculations.
Enzymatic activity (denitrification) of Paracoccus denitrificans was estimated electrochemically by reduction of duroquinone (DQ). Graphite electrodes covered with whole bacterial cells behind a dialysis membrane were used for measurement. P. denitrificans reduce nitrate and/or nitrite under anaerobic conditions to nitrogen gas. DQ acts as an electron mediator. After donation of the electrons to the respiratory system of the bacteria, produced DQ is reduced to durohydroquinone on the electrode surface electrocatalytically. P. denitrificans were exposed to low-frequency magnetic field (10 mT, 50 Hz) for 24 min. In comparison with the control samples, the reduction peak of I-E curves that represent denitrification activity of the cells decreased significantly after magnetic field exposure. The decrease of the peak current was about 20%. The CFU-colony forming units-method was used to estimate the number of surviving bacteria. After 24 min exposure of 10 mT magnetic field P. denitrificans culture on electrode indicates 21% bacterial death.
Prevalencia obezity u detí a adolescentov stúpa. Väčšina nadváhou a obezitou postihnutých detí je v starostlivosti lekárov prvého kontaktu, čo sú pediatri, rodinní lekári, nutricionisti, zdravotníci a školskí lekári ‒ a nie u špecialistov. Väčšina obéznych detí nemá zatiaľ známe vyvolávajúce ochorenie, významná časť z nich môže mať s obezitou spojené sprievodné ochorenie. Tento text má poskytnúť jednoduché praktické postupy na identifikáciu a manažment detí buď už s prítomnosťou, alebo rizikami vzniku nadváhy a obezity v zariadeniach primárnej zdravotníckej starostlivosti. Tieto rady a prostriedky sa zakladajú na údajoch z nedávno publikovaných prác, oficiálnych stanoviskách odborných spoločností spolu so skúsenosťami expertov, členov Childhood Obesity Task Force (COTF) EASO. My sme sa pokúsili použiť na dôkazoch založený postup, pri zachovaní flexibility pre praktických lekárov v oblasti, kde chýbajú v súčasnosti dôkazy s dôrazom na to, že liečba obéznych detí zahŕňa aj celé rodiny.
The prevalence of obesity among children and adolescents is on the rise. The majority of overweight or obese children are treated by primary health care providers including paediatricians, family practitioners, dieticians, nurses, and school health services ‒ and not by specialists. The majority of obese children have no underlying medical disorder causing their obesity yet a significant proportion might suffer from obesity-related co-morbidities. This text is aimed at providing simple and practical tools for the identification and management of children with or at risk of overweight and obesity in the primary care setting. The tips and tools provided are based on data from the recent body of work that has been published in this field, official statements of several scientific societies along with expert opinion provided by the members of the Childhood Obesity Task Force (COTF) of the European Association for the Study of Obesity (EASO). We have attempted to use an evidence-based approach while allowing flexibility for the practicing clinician in domains where evidence is currently lacking and ensuring that treating the obese child involves the entire family as well.
[1st ed.] 123 s.
- MeSH
- bolest MeSH
- učební obory MeSH
- Konspekt
- Výchova a vzdělávání
- NLK Obory
- neurologie
- výchova a vzdělávání pracovníků ve zdravotnictví
Substantial research over the past two decades has established that magnetic fields affect fundamental cellular processes, including gene expression. However, since biological cells and subcellular components exhibit diamagnetic behavior and are therefore subjected to very small magnetic forces that cannot directly compete with the viscoelastic and bioelectric intracellular forces responsible for cellular machinery functions, it becomes challenging to understand cell-magnetic field interactions and to reveal the mechanisms through which these interactions differentially influence gene expression in cells. The limited understanding of the molecular mechanisms underlying biomagnetic effects has hindered progress in developing effective therapeutic applications of magnetic fields. This review examines the expanding body of literature on genetic events during static and low-frequency magnetic field exposure, focusing particularly on how changes in gene expression interact with cellular machinery. To address this, we conducted a systematic review utilizing extensive search strategies across multiple databases. We explore the intracellular mechanisms through which transcription functions may be modified by a magnetic field in contexts where other cellular signaling pathways are also activated by the field. This review summarizes key findings in the field, outlines the connections between magnetic fields and gene expression changes, identifies critical gaps in current knowledge, and proposes directions for future research. LEVEL OF EVIDENCE: NA TECHNICAL EFFICACY: Stage 4.
- MeSH
- exprese genu * účinky záření MeSH
- lidé MeSH
- magnetické pole * MeSH
- regulace genové exprese * účinky záření fyziologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- systematický přehled MeSH
Příspěvek je deskriptivní studií zabývající se základními dynamickými charakteristikami hlavních technik volného způsobu běhu na lyžích. Byla měřena a analyzována síla, kterou běžci vytváří dolními končetinami při odrazu u bruslení oboustranného dvoudobého a jednodobého, a zjišťována doba odrazu. Měření bylo provedeno pomocí systému Pedar (Novel, SRN). Sledovanou skupinou byli běžci na úrovni I. výkonnostní třídy, kteří se umístili do 25. místa v žebříčku SLČR. Byly zjištěny rozdílné hodnoty maximální síly při odrazu mezi sledovanými technikami, vyšší síla byla vždy zjištěna při bruslení na rovině ve srovnání se stoupáním, a to jak pro tréninkovou, tak i závodní rychlost. Průměrné hodnoty maximální síly na rovině u bruslení dvoudobého dosáhly 1,2−1,5násobku hmotnosti běžců, u jednodobého v rozmezí 1,1–1,4násobků hmotnosti. Ve stoupání činily tyto hodnoty 1,2–1,4násobek hmotnosti pro bruslení oboustranné dvoudobé a 1–1,2 násobek pro jednodobé.
The contribution is the descriptive study which is dealing with the basic kinetic characteristics of main cross country ski skating techniques. We observed and analysed the leg force during the stroke for open field skating or V1 and V2 skating. Next we studied the time of the stroke (kick). The measurement was made with the help of the system Pedar [Novel, GER]. Our observed group created the high performance level competitors, who`s placed till 25th in the SLCR ranking. We found out the various figures of maximal force for both technique, usually higher for open field and V1 technique than for V2 skating, the higher force during the skating on the fl at terrain than on the slope for training and race speed. The average value of maximal force on the flat terrain during open field or V1 skating were 1,2 – 1,5 multiple of body weight (BW), for V2 skating we found 1,1 – 1,4 (BW). In the uphill the value were 1,2 – 1,4 (BW) for open field or V1 skating and 1 – 1,2 (BW) for V2.
- Klíčová slova
- bruslení oboustranné dvoudobé, bruslení oboustranné jednodobé, doba odrazu, dynamická analýza, odraz, síla odrazu,
- MeSH
- biomechanika * MeSH
- dolní končetina MeSH
- lidé MeSH
- lyžování * MeSH
- mladý dospělý * MeSH
- pilotní projekty MeSH
- svalová síla fyziologie MeSH
- Check Tag
- lidé MeSH
- mladý dospělý * MeSH
The coarse-grained Martini force field is widely used in biomolecular simulations. Here we present the refined model, Martini 3 ( http://cgmartini.nl ), with an improved interaction balance, new bead types and expanded ability to include specific interactions representing, for example, hydrogen bonding and electronic polarizability. The updated model allows more accurate predictions of molecular packing and interactions in general, which is exemplified with a vast and diverse set of applications, ranging from oil/water partitioning and miscibility data to complex molecular systems, involving protein-protein and protein-lipid interactions and material science applications as ionic liquids and aedamers.
To explore cellular responses to high magnetic fields (HMF), we present a model of the interactions of cells with a homogeneous HMF that accounts for the magnetic force exerted on paramagnetic/diamagnetic species. There are various chemical species inside a living cell, many of which may have large concentration gradients. Thus, when an HMF is applied to a cell, the concentration-gradient magnetic forces act on paramagnetic or diamagnetic species and can either assist or oppose large particle movement through the cytoplasm. We demonstrate possibilities for changing the machinery in living cells with HMFs and predict two new mechanisms for modulating cellular functions with HMFs via (i) changes in the membrane potential and (ii) magnetically assisted intracellular diffusiophoresis of large proteins. By deriving a generalized form for the Nernst equation, we find that an HMF can change the membrane potential of the cell and thus have a significant impact on the properties and biological functionality of cells. The elaborated model provides a universal framework encompassing current studies on controlling cell functions by high static magnetic fields. Bioelectromagnetics. 2021;42:27-36. © 2020 Bioelectromagnetics Society.
