Equivalent Reactions Research Articles

Guanidine Hydrochloride-Induced Hepatitis B Virus Capsid Disassembly Hysteresis.

Hepatitis B virus (HBV) displays remarkable self-assembly capabilities that interest the scientific community and biotechnological industries as HBV is leading to an annual mortality of up to 1 million people worldwide (especially in Africa and Southeast Asia). When the ionic strength is increased, hepatitis B virus-like particles (VLPs) can assemble from dimers of the first 149 residues of the HBV capsid protein core assembly domain (Cp149). Using solution small-angle X-ray scattering, we investigated the disassembly of the VLPs by titrating guanidine hydrochloride (GuHCl). Measurements were performed with and without 1 M NaCl, added either before or after titrating GuHCl. Fitting the scattering curves to a linear combination of atomic models of Cp149 dimer (the subunit) and T = 3 and T = 4 icosahedral capsids revealed the mass fraction of the dimer in each structure in all the titration points. Based on the mass fractions, the variation in the dimer-dimer association standard free energy was calculated as a function of added GuHCl, showing a linear relation between the interaction strength and GuHCl concentration. Using the data, we estimated the energy barriers for assembly and disassembly and the critical nucleus size for all of the assembly reactions. Extrapolating the standard free energy to [GuHCl] = 0 showed an evident hysteresis in the assembly process, manifested by differences in the dimer-dimer association standard free energy obtained for the disassembly reactions compared with the equivalent assembly reactions. Similar hysteresis was observed in the energy barriers for assembly and disassembly and the critical nucleus size. The results suggest that above 1.5 M, GuHCl disassembled the capsids by attaching to the protein and adding steric repulsion, thereby weakening the hydrophobic attraction.

Stereoselective Alder-Ene Reactions of Bicyclo[1.1.0]butanes: Facile Synthesis of Cyclopropyl- and Aryl-Substituted Cyclobutenes.

Bicyclo[1.1.0]butanes (BCBs), strained carbocycles comprising two fused cyclopropane rings, have become well-established building blocks in organic synthesis, medicinal chemistry, and chemical biology due to their diverse reactivity profile with radicals, nucleophiles, cations, and carbenes. The constraints of the bicyclic ring system confer high p-character on the interbridgehead C-C bond, leading to this broad reaction profile; however, the use of BCBs in pericyclic processes has to date been largely overlooked in favor of such stepwise, non-concerted additions. Here, we describe the use of BCBs as substrates for ene-like reactions with strained alkenes and alkynes, which give rise to cyclobutenes decorated with highly substituted cyclopropanes and arenes. The former products are obtained from highly stereoselective reactions with cyclopropenes, generated in situ from vinyl diazoacetates under blue light irradiation (440 nm). Cyclobutenes featuring a quaternary aryl-bearing carbon atom are prepared from equivalent reactions with arynes, which proceed in high yields under mild conditions. Mechanistic studies highlight the importance of electronic effects in this chemistry, while computational investigations support a concerted pathway and rationalize the excellent stereoselectivity of reactions with cyclopropenes.

Monitoring Expression of Balance during Therapy in Children with Postural Disorders.

In the literature, we find information about the impact of changes in the shape of the spine on the efficiency of equivalent reactions, and we also find information about the methods and effects of physiotherapy in improving equivalent reactions. However, there is a lack of publications showing the process of changes taking place over time and defining their nature at individual stages of treatment. The aim of this study is to present the process of monitoring the expression of balance in patients aged 8-12 years with postural disorders, in the course of the therapeutic process. The shape of the spine and the efficiency of equilibrium reactions in standing posture and during gait were assessed in all the subjects. The subjects were put into two groups: with a shape-of-spine disorder and without one. The recommended set of therapeutic activities in home conditions lasted about 20 min and was performed by the child with a parent's supervision. The therapeutic program was based on elements of neurophysiological methods: Vojta and PNF. The following parameters were measured: the maximum movement of the center of pressure (CoP) in the frontal plane during gait, the maximum movement of the CoP in the sagittal plane, the movement of the CoP in the frontal plane in static conditions and the movement of the CoP in the sagittal plane in static conditions. Six statistically significant differences were recorded, and all of them were related to measurement I. The Friedman test result was statistically significant for all the indexes. Post hoc analyses were performed using the Dunn-Bonferroni test. The children with shape-of-spine disorders had a lower efficiency of equivalent reactions in relation to the children without disorders. The therapy with the application of neurophysiological methods in the treatment of shape-of-spine disorders improved equilibrium reactions in these patients. Long-lasting and thorough observations of the therapeutic process in children with shape-of-spine disorders should include the monitoring of the efficiency of equilibrium reactions.

Pd‐Catalyzed Mizoroki‐Heck Annulation and Equivalent Aminocarbonylation Reactions Enabled by Mo(CO)6‐Mediated Direct Reduction of Nitro Derivatives

AbstractA Pd‐catalyzed Mizoroki‐Heck annulation/equivalent aminocarbonylation reaction of alkene‐tethered aryl iodides with nitro compounds is accomplished, providing facile access to diverse carbamoyl‐substituted benzoheterocycles, such as indolin‐2‐ones and 2,3‐dihydrobenzofurans, in moderate to good yields. The cost‐effective Mo(CO)6 complex is discovered to be a solid carbonyl (CO) source and an ideal reducing agent, enabling the efficient production of the desired benzoheterocycles with broad substrate scope tolerance, including both nitroarenes and nitroalkanes under external reductant‐free conditions.

Perception of the COVID-19 pandemic by individuals who previously sought psychiatric assistance

IntroductionCOVID-19 pandemic leads to high levels of stress. Individuals who have previously sought psychiatric assistance are more sensitive.ObjectivesAnalysis of the perception of the pandemic by people who have previously sought psychiatric care.MethodsAn internet-survey (20.03.2020 - 13.01.2021) (N=659; 152 – previously sought psychiatric assistance); included SCL-90-R; questions about the levels of anxiety, depression, and fear (assessed on 0-10 scale); question about opinion on COVID-19 pandemic (coded further on the basis of meaning); question about epidemiological situation of COVID-19 in respondents’ places of residence and their social circles.ResultsIndividuals who had previously sought psychiatric assistance demonstrated higher levels of anxiety (5,533±2,489 versus 4,774±2,590), depression (4,945±2,926 versus 3,861±2,988), and fear (0,195±0,397 versus 0,278±0,448). They showed roughly equivalent reactions to both anticipated and real danger (z-score GSI of SCL-90-R 0,90 versus 0,90 for anticipated and real danger respectively), the same indicator of the control group (0,53 and 0,65). In statements about the pandemic, they are more often referred to the topic of “positive effects” of pandemic (3,30% versus 0,99%), expressed “curiosity” (5,92% versus 2,37%). They were less drawn to conspiracy (9,87% versus 16,17%), and exploited more readily the topic “about myself” (20,39% versus 13,21%), negative images of “the present” (3,64% versus с 1,58%) and “the future” (15,79% versus 9, 47%), vocabulary of “anger” (5,92% versus 2,17%).ConclusionsIndividuals who had previously sought psychiatric assistance were ambivalent in their attitudes towards pandemic, and tended to concentrate more on feelings and the negative vision of the future. They perceived anticipated danger roughly equivalent to real danger.DisclosureNo significant relationships.

Understanding Ball Milling Mechanochemical Processes with DFT Calculations and Microkinetic Modeling.

Mechanochemistry is an emerging field with many potential applications in sustainable chemistry. But despite the growing interest in the field, its underlying mechanistic foundations are not fully understood yet. This work presents the application of computational tools, such as DFT calculations in continuum and microkinetic modeling, to the analysis of mechanically activated procedures. Two reactions reported in previous experimental publications were studied: (i) a series of Diels-Alder reactions and (ii) the synthesis of sulfonylguanidines. Calculations succeed in reproducing experimentally reported reaction times. The procedures were mostly standard, coupled with some sensitive choices in terms of starting concentrations and dielectric constant. This means that these particular reactions accelerated by ball milling followed the same mechanism as the equivalent reactions in solution. The implications of this result on the general picture of mechanochemical processes are discussed.

Anomalous magnetism of uranium(IV)-oxo and -imido complexes reveals unusual doubly degenerate electronic ground states

Anomalous magnetism of uranium(IV)-oxo and -imido complexes reveals unusual doubly degenerate electronic ground states

The effects of nitric oxide or oxygen on the stable products formed from the tyrosine phenoxyl radical

Tyrosine is a critical component of many proteins and can be the subject of oxidative posttranslational modifications. Furthermore, the oxidation of tyrosine residues to phenoxyl radicals, sometimes quite stable, is essential for some enzymatic functions. The lifetime and fate of tyrosine phenoxyl radicals in biological systems are largely driven by the availability and proximity of oxidants and reductants. Tyrosine phenoxyl radicals have extremely low reactivity with molecular oxygen whereas reactions with nitric oxide are diffusion controlled. This is in contrast to equivalent reactions with tryptophanyl and cysteinyl radicals where reactions with oxygen are much faster. Despite, the quite disparate apparent reactivity of tyrosine phenoxyl radicals with oxygen and nitric oxide being known, the products of the reactions are not well established. Changes in the levels from expected basal concentrations of stable products resulting from tyrosine phenoxyl radicals, for example naturally occurring 3,3′-dityrosine, 3-nitrotyrosine, and 3-hydroxytyrosine, can be indicative of oxidative and/or nitrosative stress. Using the radiolytic generation of specific oxidizing radicals to form tyrosine phenoxyl radicals in an aqueous solution at a known rate, we have compared the products in the absence and presence of nitric oxide or oxygen. Possible reactions of the phenoxyl radicals with oxygen remain unclear although we show evidence for a small decrease in the yield of dityrosine and loss of tyrosine in the presence of 20% oxygen. Low concentrations of nitric oxide in anoxic conditions react with tyrosine phenoxyl radicals, by what is most probably through the formation of an unstable intermediate, regenerating tyrosine and forming nitrite.

Altered relaxation dynamics of excited state reactions by confinement in reverse micelles probed by ultrafast fluorescence up-conversion.

Chemical reactions in confined environments are important in areas as diverse as heterogenous catalysis, environmental chemistry and biochemistry, yet they are much less well understood than the equivalent reactions in either the gas phase or in free solution. The understanding of chemical reactions in solution was greatly enhanced by real time studies of model reactions, through ultrafast spectroscopy (especially when supported by molecular dynamics simulation). Here we review some of the efforts that have been made to adapt this approach to the investigation of reactions in confined media. Specifically, we review the application of ultrafast fluorescence spectroscopy to measure reaction dynamics in the nanoconfined water phase of reverse micelles, as a function of the droplet radius and the charge on the interface. Methods of measurement and modelling of the reactions are outlined. In all of the cases studied (which are focused on ultrafast intramolecular reactions) the effect of confinement was to suppress the reaction. Even in the largest micelles the result in the bulk aqueous phase was not usually recovered, suggesting an important role for specific interactions between reactant and environment, for example at the interface. There was no simple one-to-one correspondence with direct measures of the dynamics of the confined phase. Thus, understanding the effect of confinement on reaction rate appears to require not only knowledge of the dynamics of the reaction in solutions and the effect of confinement on the medium, but also of the interaction between reactant and confining medium.

Reactions of Bifunctional Perfluoroarylsilanes with Activated C-F Bonds in Perfluorinated Arenes.

Reactions of bifunctional perfluoroarylsilanes, p- and m-C6F4(SiMe3)2 as well as o-BrC6F4SiMe3, with substituted perfluoroarenes having electron-withdrawing groups were investigated using NMR and density functional theory calculation techniques. The C–F bond in perfluoroarenes was activated by the para-position of an electron-withdrawing group, such as CF3, C6F5, CN, and NO2. The reaction of C6F4(SiMe3)2 mainly occurred at the para-position of the perfluoroarenes and also occurred at the ortho-position of C6F5CN and C6F5NO2. Two equivalent reactions of perfluoroarenes with bifunctional p- and m-C6F4(SiMe3)2 provided disubstituted perfluoroarenes, along with a small amount of protonated monosubstituted perfluoroarenes. The reaction of o-BrC6F4SiMe3 with the CF3- and CN-substituted pentafluorobenzenes provided unexpected coupling products between C–Br and C–F bonds, in addition to the coupling products between C–SiMe3 and C–F bonds.

Oxidative Cleavage of Alkene C=C Bonds Using a Manganese Catalyzed Oxidation with H2O2 Combined with Periodate Oxidation.

A one‐pot multi‐step method for the oxidative cleavage of alkenes to aldehydes/ketones under ambient conditions is described as an alternative to ozonolysis. The first step is a highly efficient manganese catalyzed epoxidation/cis‐dihydroxylation of alkenes. This step is followed by an Fe(III) assisted ring opening of the epoxide (where necessary) to a 1,2‐diol. Carbon–carbon bond cleavage is achieved by treatment of the diol with sodium periodate. The conditions used in each step are not only compatible with the subsequent step(s), but also provide for increased conversion compared to the equivalent reactions carried out on the isolated intermediate compounds. The described procedure allows for carbon–carbon bond cleavage in the presence of other alkenes, oxidation sensitive moieties and other functional groups; the mild conditions (r.t.) used in all three steps make this a viable general alternative to ozonolysis and especially for use under flow or continuous batch conditions.

The influence of Pilates exercises on body balance in the standing position of hearing impaired people

Purpose: Hearing impairment may affect the body posture maintenance. The aim of the study was to evaluate the effect of modified Pilates exercise program on the body posture maintenance in hearing impaired people.Methods: Eighty students (aged 13–24) were enrolled and randomly allocated into two groups: test group (n = 41) which attended an original program based on modified Pilates exercises and control group (n = 39) which attended standard physical education classes. Stabilographic tests were conducted at baseline and after 6-week training program.Results: Both groups showed improved control of body balance in a standing position manifested in reductions of the length of path, surface area, and speed of deflection. Modified Pilates program was significantly more effective in improving body balance control in relaxed posture and with feet together than standard physical education classes. The greater efficiency of the modified Pilates program was expressed in a significant improvement in balance control parameters, i.e., path length, surface area, and speed of deflection.Conclusions: The modified Pilates program was more effective in improving body balance control in the hearing impaired people than standard physical education classes. Modification of physical activity recommendations for hearing impaired students may be considered; however, further research is required.Implications for RehabilitationHearing impairment impacts the mental, social and, physical spheres of life as well as deteriorates equivalent reactions and the way body posture is maintained.In hearing impaired people, control of body balance and muscle coordination is often disturbed, thus more attention should be paid to exercises associated with balance which may improve the ability to learn and develop motor skills.Modified Pilates program was significantly more effective in improving body balance control than standard physical education classes in hearing impaired people.

Soft Substrates Containing Hyaluronan Mimic the Effects of Increased Stiffness on Morphology, Motility, and Proliferation of Glioma Cells.

Unlike many other cancer cells that grow in tumors characterized by an abnormally stiff collagen-enriched stroma, glioma cells proliferate and migrate in the much softer environment of the brain, which generally lacks the filamentous protein matrix characteristic of breast, liver, colorectal, and other types of cancer. Glial cell-derived tumors and the cells derived from them are highly heterogeneous and variable in their mechanical properties, their response to treatments, and their properties in vitro. Some glioma samples are stiffer than normal brain when measured ex vivo, but even those that are soft in vitro stiffen after deformation by pressure gradients that arise in the tumor environment in vivo. Such mechanical differences can strongly alter the phenotype of cultured glioma cells. Alternatively, chemical signaling might elicit the same phenotype as increased stiffness by activating intracellular messengers common to both initial stimuli. In this study the responses of three different human glioma cell lines to changes in substrate stiffness are compared with their responses on very soft substrates composed of a combination of hyaluronic acid and a specific integrin ligand, either laminin or collagen I. By quantifying cell morphology, stiffness, motility, proliferation, and secretion of the cytokine IL-8, glioma cell responses to increased stiffness are shown to be nearly identically elicited by substrates containing hyaluronic acid, even in the absence of increased stiffness. PI3-kinase activity was required for the response to hyaluronan but not to stiffness. This outcome suggests that hyaluronic acid can trigger the same cellular response, as can be obtained by mechanical force transduced from a stiff environment, and demonstrates that chemical and mechanical features of the tumor microenvironment can achieve equivalent reactions in cancer cells.

Comparison of intradermal and percutaneous testing to histamine, saline and nine allergens in healthy adult cats.

Intradermal testing (IDT) in cats has potential limitations; this has led to an interest in novel testing methods. A pilot study demonstrated that healthy cats produced reliable percutaneous glycerinated (PG) histamine wheals, whereas percutaneously applied glycerosaline did not lead to wheal formation. The purpose of this study was to determine if percutaneously applied aqueous and glycerinated allergens would lead to irritant reactions in healthy cats. Percutaneous testing (PCT) with both glycerinated and aqueous allergens and IDT were compared in twelve healthy cats. The lateral thorax was clipped and histamine, saline and nine allergens were tested in rows. Objective and subjective evaluations were performed at 15, 20 and 25 min, and 4 h. Results were evaluated as positive or negative at 15, 20, 25 min and 4 h. Skin test reactions for intradermal (ID) histamine wheals were larger when compared to PG and percutaneous aqueous (PA) at the immediate reading points (P < 0.05) subjectively and objectively; however, PG was not significantly different from ID when compared as either positive (2-4) or negative (0-1). PG histamine and allergen reactions, when present, were larger than equivalent PA reactions. PG and PA allergens did not cause irritant reactions at tested concentrations. Bassia scoparia (kochia), when tested at 1000 PNU/mL with IDT, was suspected to be an irritant. Percutaneously (PCT) applied allergens did not cause irritant reactions in healthy cats. PG histamine wheals, although smaller than ID histamine wheals, were easily recognizable and PCT was simple to perform.

Student BMJ comes of age

Betaine lipids are ether-linked, nonphosphorous glycerolipids that resemble the more commonly known phosphatidylcholine in overall structure. Betaine lipids are abundant in many eukaryotes such as nonseed plants, algae, fungi, and amoeba. Some of these organisms are entirely devoid of phosphatidylcholine and, instead, contain a betaine lipid such as diacylglyceryl-O-4′-(N,N,N,-trimethyl)homoserine. Recently, this lipid also was discovered in the photosynthetic purple bacterium Rhodobacter sphaeroides where it seems to replace phosphatidylcholine under phosphate-limiting growth conditions. This discovery provided the opportunity to study the biosynthesis of betaine lipids in a bacterial model system. Mutants of R. sphaeroides deficient in the biosynthesis of the betaine lipid were isolated, and two genes essential for this process, btaA and btaB, were identified. It is proposed that btaA encodes an S-adenosylmethionine:diacylglycerol 3-amino-3-carboxypropyl transferase and btaB an S-adenosylmethionine-dependent N-methyltransferase. Both enzymatic activities can account for all reactions of betaine lipid head group biosynthesis. Because the equivalent reactions have been proposed for different eukaryotes, it seems likely that orthologs of btaA/btaB may be present in other betaine lipid-containing organisms.

Mechanistic studies on the dibenzofuran formation from phenanthrene, fluorene and 9-fluorenone.

We carried out molecular orbital theory calculations for the homogeneous gas‑phase formation of dibenzofuran from phenanthrene, fluorene, 9-methylfluorene and 9-fluorenone. Dibenzofuran will be formed if ∙OH adds to C8a, and the order of reactivity follows as 9-fluorenone > 9-methylfluorene > fluorene > phenanthrene. The oxidations initiated by ClO∙ are more favorable processes, considering that the standard reaction Gibbs energies are at least 21.63 kcal/mol lower than those of the equivalent reactions initiated by ∙OH. The adding of ∙OH and then O2 to phenanthrene is a more favorable route than adding ∙OH to C8a of phenanthrene, when considering the greater reaction extent. The reaction channel from fluorene and O2 to 9-fluorenone and H2O seems very important, not only because it contains only three elementary reactions, but because the standard reaction Gibbs energies are lower than −80.07 kcal/mol.

ChemInform Abstract: Metabolic Engineering: The Ultimate Paradigm for Continuous Pharmaceutical Manufacturing

AbstractReview: [32 refs.

Application of a semi-homodesmotic approach in estimating ring strain energies (RSEs) of highly substituted cyclobutanes: RSEs for c-C4R8 that make sense.

A semi-homodesmotic method for estimating of ring strain energies (RSEs) of substituted cyclopropanes is applied to substituted cyclobutanes c-C4HxR8-x (R = F, Cl, Me; x = 0, 2, 4). Whereas (hyper)homodesmotic reaction methods predict implausible results, particularly for c-C4R8, the semi-homodesmotic approach provides RSEs consistent with thermodynamic and independent computational data regardless of the degree of substitution. The method requires employing homodesmotic group equivalent reactions only for disubstituted cyclobutanes, relying solely on absolute energy calculations for more substituted rings. We find that, consistent with QTAIM data, RSEs increase with substitution regardless of the electronic nature of R, although the increase is more dramatic when R is electron-withdrawing. Overall, the semi-homodesmotic method is simpler than hyperhomodesmotic approaches and gives more trustworthy results.

A Semi-homodesmotic Approach for Estimating Ring Strain Energies (RSEs) of Highly Substituted Cyclopropanes That Minimizes Use of Acyclic References and Cancels Steric Interactions: RSEs for c-C3R6 that Make Sense

Estimation of ring strain energies (RSEs) of substituted cyclopropanes c-C(3)H(x)R(6-x) (R = F, Cl, Me; x = 0, 2, 4) using homodesmotic reaction methods has been plagued by implausible results. Prior work suggests that this stems from poorly canceled interactions between substituents on the acyclic reference molecules. We report a semi-homodesmotic approach that minimizes use of acyclic references, focusing instead on canceling substituent interactions. The method requires employing homodesmotic group equivalent reactions only for disubstituted cyclopropanes and relies solely on absolute energy calculations for more substituted rings. This provides RSEs consistent with chemical intuition regardless of the degree of substitution. We find that RSEs increase with substitution regardless of the electronic nature of R, although the increase is more dramatic when R is electron-withdrawing. The RSEs determined are consistent with QTAIM data, which show that progressive substitution always increases critical path angles. Overall, the semi-homodesmotic approach is simpler than hyperhomodesmotic reaction methods, and gives more trustworthy results.

Cutaneous adverse drug reactions induced by Oxcarbazepine

Poster background Oxcarbazepine (OXC) is a structural analog of carbamazepine (CBZ). OXC is considered a promising alternative medication for patients who cannot tolerate CBZ because of its equivalent clinical effiecacy and fewer cutaneous adverse drug reactions (cADRs) compared to CBZ. HLAB*15:02 allele was shown to strongly associate with carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) in Chinese and Southeast Asian populations.However,the epidemiological data about OXC-induced cADRs in recent years is limited. This study aims to investigate the clinical characteristics of OXC-induced cADRs and their genetic associations with HLA-B*15:02.