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1.
Nat Rev Neurosci ; 25(5): 289-312, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38609551

RESUMEN

Language behaviour is complex, but neuroscientific evidence disentangles it into distinct components supported by dedicated brain areas or networks. In this Review, we describe the 'core' language network, which includes left-hemisphere frontal and temporal areas, and show that it is strongly interconnected, independent of input and output modalities, causally important for language and language-selective. We discuss evidence that this language network plausibly stores language knowledge and supports core linguistic computations related to accessing words and constructions from memory and combining them to interpret (decode) or generate (encode) linguistic messages. We emphasize that the language network works closely with, but is distinct from, both lower-level - perceptual and motor - mechanisms and higher-level systems of knowledge and reasoning. The perceptual and motor mechanisms process linguistic signals, but, in contrast to the language network, are sensitive only to these signals' surface properties, not their meanings; the systems of knowledge and reasoning (such as the system that supports social reasoning) are sometimes engaged during language use but are not language-selective. This Review lays a foundation both for in-depth investigations of these different components of the language processing pipeline and for probing inter-component interactions.


Asunto(s)
Encéfalo , Lenguaje , Humanos , Encéfalo/fisiología , Red Nerviosa/fisiología , Vías Nerviosas/fisiología , Mapeo Encefálico
2.
J Neurosci ; 43(34): 6061-6083, 2023 08 23.
Artículo en Inglés | MEDLINE | ID: mdl-37532464

RESUMEN

Exposure to elevated doses of ionizing radiation, such as those in therapeutic procedures, catastrophic accidents, or space exploration, increases the risk of cognitive dysfunction. The full range of radiation-induced cognitive deficits is unknown, partly because commonly used tests may be insufficiently sensitive or may not be adequately tuned for assessing the fine behavioral features affected by radiation. Here, we asked whether γ-radiation might affect learning, memory, and the overall ability to adapt behavior to cope with a challenging environment (cognitive/behavioral flexibility). We developed a new behavioral assay, the context discrimination Morris water maze (cdMWM) task, which is hippocampus-dependent and requires the integration of various contextual cues and the adjustment of search strategies. We exposed male mice to 1 or 5 Gy of γ rays and, at different time points after irradiation, trained them consecutively in spatial MWM, reversal MWM, and cdMWM tasks, and assessed their learning, navigational search strategies, and memory. Mice exposed to 5 Gy performed successfully in the spatial and reversal MWM tasks; however, in the cdMWM task 6 or 8 weeks (but not 3 weeks) after irradiation, they demonstrated transient learning deficit, decreased use of efficient spatially precise search strategies during learning, and, 6 weeks after irradiation, memory deficit. We also observed impaired neurogenesis after irradiation and selective activation of 12-week-old newborn neurons by specific components of cdMWM training paradigm. Thus, our new behavioral paradigm reveals the effects of γ-radiation on cognitive flexibility and indicates an extended timeframe for the functional maturation of new hippocampal neurons.SIGNIFICANCE STATEMENT Exposure to radiation can affect cognitive performance and cognitive flexibility - the ability to adapt to changed circumstances and demands. The full range of consequences of irradiation on cognitive flexibility is unknown, partly because of a lack of suitable models. Here, we developed a new behavioral task requiring mice to combine various types of cues and strategies to find a correct solution. We show that animals exposed to γ-radiation, despite being able to successfully solve standard problems, show delayed learning, deficient memory, and diminished use of efficient navigation patterns in circumstances requiring adjustments of previously used search strategies. This new task could be applied in other settings for assessing the cognitive changes induced by aging, trauma, or disease.


Asunto(s)
Hipocampo , Aprendizaje , Ratones , Masculino , Animales , Hipocampo/fisiología , Neurogénesis/fisiología , Cognición/fisiología , Neuronas/fisiología , Aprendizaje por Laberinto/fisiología
3.
Clin Chem ; 70(3): 528-537, 2024 03 02.
Artículo en Inglés | MEDLINE | ID: mdl-38431279

RESUMEN

BACKGROUND: Lipid profiling is central for coronary artery disease (CAD) risk assessment. Nonadherence or unreported use of lipid-lowering drugs, particularly statins, can significantly complicate the association between lipid profile measures and CAD clinical outcomes. By combining medication history evaluation with statin analysis in plasma, we determined the effects of inaccurately reported statin use on lipid profile measures and their association with CAD risk. METHODS: We compared medication history of statin use with statin concentration measurements, by liquid chromatography-tandem mass spectrometry, in 690 participants undergoing coronary angiography (63 ± 11 years of age). Nominal logistic regression was employed to model CAD diagnosis with statin measurements, phenotypic, and lipid profile characteristics. RESULTS: Medication history of statin use was confirmed by statin assay for 81% of the patients. Surprisingly, statins were detected in 46% of patients without statin use records. Nonreported statin use was disproportionately higher among older participants. Stratifying samples by statin history resulted in underestimated LDL-lipid measures. Apolipoprotein B concentrations had a significant inverse CAD association, which became nonsignificant upon re-stratification using the statin assay data. CONCLUSIONS: Our study uncovered prominent discrepancies between medication records and actual statin use measured by mass spectrometry. We showed that inaccurate statin use assessments may lead to overestimation and underestimation of LDL levels in statin user and nonuser categories, exaggerating the reverse epidemiology association between LDL levels and CAD diagnosis. Combining medication history and quantitative statin assay data can significantly improve the design, analysis, and interpretation of clinical and epidemiological studies.


Asunto(s)
Enfermedad de la Arteria Coronaria , Inhibidores de Hidroximetilglutaril-CoA Reductasas , Humanos , Angiografía Coronaria/métodos , Enfermedad de la Arteria Coronaria/diagnóstico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Lípidos , Medición de Riesgo , Factores de Riesgo , Persona de Mediana Edad , Anciano
4.
Am J Public Health ; 114(1): 98-107, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38091559

RESUMEN

Objectives. To examine cannabis use prevalence and its association with tobacco cessation among adults enrolled in cigarette smoking cessation treatment before and after Canada legalized recreational cannabis in October 2018. Methods. The sample comprised 83 206 adults enrolled in primary care-based cigarette smoking cessation treatment between 2015 and 2021 in Ontario, Canada. Past-30-day cannabis use was self-reported at enrollment and cigarette smoking abstinence at 6-month follow-up. Results. Past-30-day prevalence of cannabis use increased from 20.2% in 2015 to 37.7% in 2021. The prevalence increased linearly both before and after legalization. Cannabis and tobacco co-use was associated with lower odds of self-reported cigarette smoking abstinence at 6-month follow-up than tobacco use only (24.4% vs 29.3%; odds ratio [OR] = 0.78; 95% confidence interval [CI] = 0.75, 0.81). This association was attenuated after adjustment for covariates (OR = 0.93; 95% CI = 0.89, 0.97) and weakened slightly over time. Conclusions. Cannabis use prevalence almost doubled from 2015 to 2021 among primary care patients in Ontario seeking treatment to quit cigarettes and was associated with poorer quit outcomes. Further research into the impact of cannabis policy on cannabis and tobacco co-use is warranted to mitigate harm. (Am J Public Health. 2024;114(1):98-107. https://doi.org/10.2105/AJPH.2023.307445).


Asunto(s)
Cannabis , Sistemas Electrónicos de Liberación de Nicotina , Cese del Hábito de Fumar , Productos de Tabaco , Cese del Uso de Tabaco , Adulto , Humanos , Cese del Hábito de Fumar/métodos , Ontario/epidemiología , Prevalencia
5.
Inorg Chem ; 63(11): 5199-5207, 2024 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-38447157

RESUMEN

New nitrosonium manganese(II) nitrate, (NO)Mn6(NO3)13, has been synthesized and structurally characterized. In the temperature range of 45-298 K, the crystal is hexagonal (centrosymmetric sp. gr. P63/m). Mn2+ ions are assembled into tubes along axis c with both NO3- filling and coating. The nitrosonium cation is located in the framework cavity and is disordered by a 3-fold axis. At the temperature TS1 = 190 K, a structural phase transition related to the libration of the intertube NO3 group and a small variation of Mn polyhedron is observed. Moreover, the anomalies in physical properties of (NO)Mn6(NO3)13 allow suggesting that ordering of NO+ units occurs at low temperatures. The antiferromagnetic ordering in this compound is preceded by the formation of a short-range correlation regime at about 25 K and takes place in two steps at TN1 = 12.0 K and TN2 = 8.4 K.

6.
Cereb Cortex ; 33(19): 10380-10400, 2023 09 26.
Artículo en Inglés | MEDLINE | ID: mdl-37557910

RESUMEN

The relationship between language and thought is the subject of long-standing debate. One claim states that language facilitates categorization of objects based on a certain feature (e.g. color) through the use of category labels that reduce interference from other, irrelevant features. Therefore, language impairment is expected to affect categorization of items grouped by a single feature (low-dimensional categories, e.g. "Yellow Things") more than categorization of items that share many features (high-dimensional categories, e.g. "Animals"). To test this account, we conducted two behavioral studies with individuals with aphasia and an fMRI experiment with healthy adults. The aphasia studies showed that selective low-dimensional categorization impairment was present in some, but not all, individuals with severe anomia and was not characteristic of aphasia in general. fMRI results revealed little activity in language-responsive brain regions during both low- and high-dimensional categorization; instead, categorization recruited the domain-general multiple-demand network (involved in wide-ranging cognitive tasks). Combined, results demonstrate that the language system is not implicated in object categorization. Instead, selective low-dimensional categorization impairment might be caused by damage to brain regions responsible for cognitive control. Our work adds to the growing evidence of the dissociation between the language system and many cognitive tasks in adults.


Asunto(s)
Afasia , Lenguaje , Humanos , Adulto , Encéfalo/diagnóstico por imagen , Afasia/diagnóstico por imagen
7.
Proc Natl Acad Sci U S A ; 118(37)2021 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-34508004

RESUMEN

ß cells produce, store, and secrete insulin upon elevated blood glucose levels. Insulin secretion is a highly regulated process. The probability for insulin secretory granules to undergo fusion with the plasma membrane or being degraded is correlated with their age. However, the molecular features and stimuli connected to this behavior have not yet been fully understood. Furthermore, our understanding of ß cell function is mostly derived from studies of ex vivo isolated islets in rodent models. To overcome this translational gap and study insulin secretory granule turnover in vivo, we have generated a transgenic pig model with the SNAP-tag fused to insulin. We demonstrate the correct targeting and processing of the tagged insulin and normal glycemic control of the pig model. Furthermore, we show specific single- and dual-color granular labeling of in vivo-labeled pig pancreas. This model may provide unprecedented insights into the in vivo insulin secretory granule behavior in an animal close to humans.


Asunto(s)
Animales Modificados Genéticamente/metabolismo , Membrana Celular/metabolismo , Colorantes Fluorescentes/química , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Proteínas SNARE/metabolismo , Vesículas Secretoras/metabolismo , Animales , Exocitosis , Glucosa/metabolismo , Secreción de Insulina , Masculino , Porcinos
8.
Pharm Stat ; 23(3): 370-384, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38146135

RESUMEN

Cross-over designs are commonly used in randomized clinical trials to estimate efficacy of a new treatment. They have received a lot of attention, particularly in connection with regulatory requirements for new drugs. The main advantage of using cross-over designs over conventional parallel designs is increased precision, thanks to within-subject comparisons. In the statistical literature, more recent developments are discussed in the analysis of cross-over trials, in particular regarding repeated measures. A piecewise linear model within the framework of mixed effects has been proposed in the analysis of cross-over trials. In this article, we report on a simulation study comparing performance of a piecewise linear mixed-effects (PLME) model against two commonly cited models-Grizzle's mixed-effects (GME) and Jones & Kenward's mixed-effects (JKME) models-used in the analysis of cross-over trials. Our simulation study tried to mirror real-life situation by deriving true underlying parameters from empirical data. The findings from real-life data confirmed the original hypothesis that high-dose iodine salt have significantly lowering effect on diastolic blood pressure (DBP). We further sought to evaluate the performance of PLME model against GME and JKME models, within univariate modeling framework through a simulation study mimicking a 2 × 2 cross-over design. The fixed-effects, random-effects and residual error parameters used in the simulation process were estimated from DBP data, using a PLME model. The initial results with full specification of random intercept and slope(s), showed that the univariate PLME model performed better than the GME and JKME models in estimation of variance-covariance matrix (G) governing the random effects, allowing satisfactory model convergence during estimation. When a hierarchical view-point is adopted, in the sense that outcomes are specified conditionally upon random effects, the variance-covariance matrix of the random effects must be positive-definite. The PLME model is preferred especially in modeling an increased number of random effects, compared to the GME and JKME models that work equally well with random intercepts only. In some cases, additional random effects could explain much variability in the data, thus improving precision in estimation of the estimands (effect size) parameters.


Asunto(s)
Simulación por Computador , Estudios Cruzados , Ensayos Clínicos Controlados Aleatorios como Asunto , Humanos , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto/estadística & datos numéricos , Modelos Lineales , Proyectos de Investigación , Modelos Estadísticos , Interpretación Estadística de Datos , Presión Sanguínea/efectos de los fármacos
9.
Hepatology ; 75(1): 154-169, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34433228

RESUMEN

BACKGROUND AND AIMS: Thioesterase superfamily member 2 (Them2) is highly expressed in liver and oxidative tissues, where it hydrolyzes long-chain fatty acyl-CoA esters to free fatty acids and CoA. Although mice globally lacking Them2 (Them2-/- ) are protected against diet-induced obesity, hepatic steatosis (HS), and insulin resistance (IR), liver-specific Them2-/- mice remain susceptible. The aim of this study was to test whether Them2 activity in extrahepatic oxidative tissues is a primary determinant of HS and IR. APPROACH AND RESULTS: Upon observing IR and up-regulation of Them2 in skeletal, but not cardiac, muscle of high-fat-diet (HFD)-fed wild-type compared to Them2-/- mice, we created mice with Them2 specifically deleted in skeletal (S-Them2-/- ) and cardiac muscle (C-Them2-/- ), as well as in adipose tissue (A-Them2-/- ). When fed an HFD, S-Them2-/- , but not C-Them2-/- or A-Them2-/- , mice exhibited reduced weight gain and improved glucose homeostasis and insulin sensitivity. Reconstitution of Them2 expression in skeletal muscle of global Them2-/- mice, using adeno-associated virus, was sufficient to restore excess weight gain. Increased rates of fatty acid oxidation in skeletal muscle of S-Them2-/- mice contributed to protection from HFD-induced HS by increasing VLDL triglyceride secretion rates in response to greater demand. Increases in insulin sensitivity were further attributable to alterations in production of skeletal muscle metabolites, including short-chain fatty acids, branched-chain amino acids, and pentose phosphate pathway intermediates, as well as in expression of myokines that modulate insulin responsiveness. CONCLUSIONS: These results reveal a key role for skeletal muscle Them2 in the pathogenesis of HS and IR and implicate it as a target in the management of NAFLD.


Asunto(s)
Resistencia a la Insulina/genética , Metabolismo de los Lípidos/genética , Músculo Esquelético/metabolismo , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Tioléster Hidrolasas/metabolismo , Animales , Dieta Alta en Grasa/efectos adversos , Modelos Animales de Enfermedad , Humanos , Masculino , Ratones , Ratones Noqueados , Enfermedad del Hígado Graso no Alcohólico/etiología , Enfermedad del Hígado Graso no Alcohólico/patología , Oxidación-Reducción , Tioléster Hidrolasas/genética , Regulación hacia Arriba
10.
J Phycol ; 59(1): 12-51, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36443823

RESUMEN

Cyanobacterial taxonomy is facing a period of rapid changes thanks to the ease of 16S rRNA gene sequencing and established workflows for description of new taxa. Since the last comprehensive review of the cyanobacterial system in 2014 until 2021, at least 273 species in 140 genera were newly described. These taxa were mainly placed into previously defined orders and families although several new families were proposed. However, the classification of most taxa still relied on hierarchical relationships inherited from the classical morphological taxonomy. Similarly, the obviously polyphyletic orders such as Synechococcales and Oscillatoriales were left unchanged. In this study, the rising number of genomic sequences of cyanobacteria and well-described reference strains allowed us to reconstruct a robust phylogenomic tree for taxonomic purposes. A less robust but better sampled 16S rRNA gene phylogeny was mapped to the phylogenomic backbone. Based on both these phylogenies, a polyphasic classification throughout the whole phylum of Cyanobacteria was created, with ten new orders and fifteen new families. The proposed system of cyanobacterial orders and families relied on a phylogenomic tree but still employed phenotypic apomorphies where possible to make it useful for professionals in the field. It was, however, confirmed that morphological convergence of phylogenetically distant taxa was a frequent phenomenon in cyanobacteria. Moreover, the limited phylogenetic informativeness of the 16S rRNA gene, resulting in ambiguous phylogenies above the genus level, emphasized the integration of genomic data as a prerequisite for the conclusive taxonomic placement of a vast number of cyanobacterial genera in the future.


Asunto(s)
Cianobacterias , Filogenia , ARN Ribosómico 16S/genética , Cianobacterias/genética , Genoma , Análisis de Secuencia de ADN
11.
J Chem Phys ; 158(2): 024902, 2023 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-36641402

RESUMEN

Compression and interpenetration of two opposing polymer brushes formed by end-grafted adsorption-active chains are studied by the numerical self-consistent field approach and by analytical theory. For sufficiently strong polymer-surface attraction, a fraction of chains in the adsorption-active brush condenses into a near-surface layer, while the remaining ones form the outer brush with reduced effective grafting density. Analysis shows that the normal pressure in adsorption-active brushes can be understood in terms of the effective grafting density concept although the pressure at small separations is affected by the presence of the dense adsorbed phase. We propose a simple theory modification that accounts for this effect. We also formulate a procedure for extracting the value of the effective grafting density directly from the pressure vs separation curves by inverting the equation of state. In contrast to the normal pressure, the interpenetration of the two opposing adsorption-active brushes demonstrates a much more intricate behavior. At weak to moderate compressions, the effective grafting density concept works well but fails spectacularly at small interbrush separations. We identify two interpenetration regimes for adsorption-active brushes: (i) at separations larger than the ideal Gaussian coil size N1/2, the overlap of the two brushes is concentrated in the mid-plane region, in the same way as in brushes grafted onto non-attractive surfaces; (ii) at separations less than N1/2, the brush overlap is strongly enhanced in the wall regions where the attractive interaction plays an important role both in generating the dense layer for the "proper" brush and in attracting the "foreign" chains.

12.
Int J Mol Sci ; 24(23)2023 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-38069265

RESUMEN

The space environment will expose astronauts to stressors like ionizing radiation, altered gravity fields and elevated cortisol levels, which pose a health risk. Understanding how the interplay between these stressors changes T cells' response is important to better characterize space-related immune dysfunction. We have exposed stimulated Jurkat cells to simulated space stressors (1 Gy, carbon ions/1 Gy photons, 1 µM hydrocortisone (HC), Mars, moon, and microgravity) in a single or combined manner. Pro-inflammatory cytokine IL-2 was measured in the supernatant of Jurkat cells and at the mRNA level. Results show that alone, HC, Mars gravity and microgravity significantly decrease IL-2 presence in the supernatant. 1 Gy carbon ion irradiation showed a smaller impact on IL-2 levels than photon irradiation. Combining exposure to different simulated space stressors seems to have less immunosuppressive effects. Gene expression was less impacted at the time-point collected. These findings showcase a complex T cell response to different conditions and suggest the importance of elevated cortisol levels in the context of space flight, also highlighting the need to use simulated partial gravity technologies to better understand the immune system's response to the space environment.


Asunto(s)
Vuelo Espacial , Ingravidez , Humanos , Interleucina-2 , Hidrocortisona , Carbono
13.
Int J Mol Sci ; 24(9)2023 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-37175638

RESUMEN

Designing studies for lipid-metabolism-related biomarker discovery is challenging because of the high prevalence of various statin and fibrate usage for lipid-lowering therapies. When the statin and fibrate use is determined based on self-reports, patient adherence to the prescribed statin dose regimen remains unknown. A potentially more accurate way to verify a patient's medication adherence is by direct analytical measurements. Current analytical methods are prohibitive because of the limited panel of drugs per test and large sample volume requirement that is not available from archived samples. A 4-min-long method was developed for the detection of seven statins and three fibrates using 10 µL of plasma analyzed via reverse-phase liquid chromatography and tandem mass spectrometry. The method was applied to the analysis of 941 archived plasma samples collected from patients before cardiac catheterization. When statin use was self-reported, statins were detected in 78.6% of the samples. In the case of self-reported atorvastatin use, the agreement with detection was 90.2%. However, when no statin use was reported, 42.4% of the samples had detectable levels of statins, with a similar range of concentrations as the samples from the self-reported statin users. The method is highly applicable in population studies designed for biomarker discovery or diet and lifestyle intervention studies, where the accuracy of statin or fibrate use may strongly affect the statistical evaluation of the biomarker data.


Asunto(s)
Inhibidores de Hidroximetilglutaril-CoA Reductasas , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Ácidos Fíbricos/uso terapéutico , Cromatografía Liquida , Espectrometría de Masas en Tándem , Atorvastatina/uso terapéutico , Biomarcadores
14.
Inorg Chem ; 61(12): 4879-4886, 2022 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-35298134

RESUMEN

We synthesized single crystals of Na0.55Ni6(OH)3(H0.61PO4)4 (I) and polycrystals of (Na, Ni)0.64Ni5.68(OH)3(H0.67PO4)4 (II) with ellenbergerite-like structures using the hydrothermal method. The phases crystallize in the hexagonal space group P63mc with the following unit cell parameters: a = 12.5342(1) Å, c = 4.9470(1) Å, and V = 673.08(2) Å3 for I; a = 12.4708(2) Å, c = 4.9435(2) Å, and V = 665.82(2) Å3 for II; and Z = 2. Their crystal structures are based on a 3D framework built from NiO6 octahedra and PO4 tetrahedra. The difference between I and II lies in the way the structural channels are filled along the [001] direction. These channels accommodate segments of Na- and (Na, Ni)-centered chains of face-sharing octahedra in the structures I and II, respectively. The magnetic susceptibility χ and the specific heat Cp evidence pronounced low-dimensional magnetic behavior at elevated temperatures and the formation of the weakly ferromagnetic long-range order at TNI = 61 K and TNII = 63 K. Analysis of the χ(T) data within both chain and dimer spin models allows the estimation of the leading exchange interaction parameters in the compounds under study.

15.
J Chem Phys ; 156(4): 044902, 2022 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-35105057

RESUMEN

Recently, a novel class of responsive uncharged polymer brushes has been proposed [Klushin et al., J. Chem. Phys. 154(7), 074904 (2021)] where the brush-forming chains have an affinity to the substrate. For sufficiently strong surface interactions, a fraction of chains condenses into a near-surface layer, while the remaining ones form the outer brush with a reduced grafting density. The dense layer and the more tenuous outer brush can be seen as coexisting microphases. The effective grafting density of the outer brush is controlled by the adsorption strength and can be changed reversibly as a response to changes in environmental parameters. In this paper, we use numerical self-consistent field calculations to study this phenomenon in polydisperse brushes. Our results reveal an unexpected effect: Although all chains are chemically identical, shorter chains are adsorbed preferentially. Hence, with the increase in the surface affinity parameter, a reduction in the surface grafting density of the residual brush is accompanied by a change in the shape of its molecular mass distribution (MMD). In particular, an originally bidisperse brush can be effectively transformed into a nearly monodisperse one containing only the longer chain fraction. We introduce a method of assigning different chain conformations to one or the other microphase, based on analyzing tail length distributions. In a polydisperse brush with a uniform MMD, short chains are relegated to the adsorbed phase, leading to a narrower effective MMD in the residual brush. Preferential adsorption is not absolute, and longer chains are also partially involved in adsorption. As a result, not only the width of the distribution decreases but also its shape evolves away from the initial uniform distribution. We believe that the effect of preferential adsorption stems from a fundamental property of a polydisperse brush, which is characterized by a spectrum of chemical potential values for monomers belonging to chains of different lengths. Hence, preferential adsorption is also expected in polyelectrolyte brushes; moreover, brush polydispersity would affect coexistence with any other condensed phase, not necessarily related to adsorption.

16.
Pedobiologia (Jena) ; 93: 150822, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35754949

RESUMEN

The soils of streets, urban parks and suburban areas were examined for yeasts in the summer of 2020 on the territory of the southern cities of Russia and the Republic of Crimea: Krasnodar, Maykop, Sochi and Simferopol. The results of this study are compared with the results of a previous study carried out in these cities in 2019. This study was conducted three months after the lockdown due to the COVID-19 pandemic, which led to a sustained decline in household waste deposition in these areas. The number of tourists visiting these southern cities decreased significantly, and the number of walkers and visitors to urban parks fell sharply. In 2020, after the decline of household waste loads, the yeast abundance was slightly but reliably higher than in 2019. A total of 30 yeast species were observed - 11 ascomycetes and 19 basidiomycetes. This was more than in 2019 and was caused by twice as many autochthonous basidiomycetous yeast species (natural core community), which were found in urban soils only after the reduction in household waste in the environment - Apiotrichum dulcitum, A. laibachii, Saitozyma podzolica Solicoccozyma terricola. And at the same time, the proportion of clinically significant (opportunistic) yeasts, Candida sake and Meyerozyma guilliermondii, was much lower in 2020 than in 2019. Thus, the observed changes in yeast communities in urban soils could be a short-time response of the microbial community to a reduction in household waste.

17.
Int J Mol Sci ; 23(19)2022 Sep 22.
Artículo en Inglés | MEDLINE | ID: mdl-36232435

RESUMEN

The magneto-mechanical approach is a powerful technique used in many different applications in biomedicine, including remote control enzyme activity, cell receptors, cancer-selective treatments, mechanically-activated drug releases, etc. This approach is based on the use of a combination of magnetic nanoparticles and external magnetic fields that have led to the movement of such nanoparticles with torques and forces (enough to change the conformation of biomolecules or even break weak chemical bonds). However, despite many theoretical and experimental works on this topic, it is difficult to predict the magneto-mechanical effects in each particular case, while the important results are scattered and often cannot be translated to other experiments. The main reason is that the magneto-mechanical effect is extremely sensitive to changes in any parameter of magnetic nanoparticles and the environment and changes in the parameters of the applied magnetic field. Thus, in this review, we (1) summarize and propose a simplified theoretical explanation of the main factors affecting the efficiency of the magneto-mechanical approach; (2) discuss the nature of the MNP-mediated mechanical forces and their order of magnitude; (3) show some of the main applications of the magneto-mechanical approach in the control over the properties of biological systems.


Asunto(s)
Campos Magnéticos , Nanopartículas , Magnetismo
18.
Int J Mol Sci ; 23(24)2022 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-36555299

RESUMEN

Unusual rearrangements were shown to accompany Brønsted acid-assisted peri-annulations of 1H-perimidines with 5-alkynylpyrimidines. These transformations take different routes depending on the nature of acetylene precursor, and lead to the formation of 7-formyl-1,3-diazopyrenes.


Asunto(s)
Acetileno , Quinazolinas , Catálisis
19.
Inorg Chem ; 60(13): 9461-9470, 2021 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-34128644

RESUMEN

A novel modification of the KCoPO4, δ-phase has been prepared by hydrothermal synthesis at 553 K. The compound crystallizes in the orthorhombic system with the unit-cell parameters a = 8.5031(8), b = 10.2830(5), c = 54.170(4) Å. The crystal structure was determined based on synchrotron low-temperature single-crystal X-ray diffraction data obtained from an inversion twin in the space group P212121 and refined to R = 0.077 for 5156 reflections with I > 3σ(I). The δ-KCoPO4 possesses a new structure type which is based on a framework built from sharing vertices Co- and P-centered tetrahedra. The {CoPO4-}∞ construction of tetrahedra may be described as assembled from networks formed by two topologically diverse six-membered rings of tetrahedra stacked together through vertex-bridging contacts along the a axis. The ratio of the (UUUDDD) and (UUDUDD) rings, where (U) and (D) denote the orientation of the tetrahedra in the six-membered rings up and down relative to the plane grids, is equal to 5:1. The (UUDUDD) rings form bands parallel to the [010] direction each surrounded from both sides along the c axis by slabs of five ribbons width having alternative (UUUDDD) topology. Open in the [100] direction channels incorporate K+ ions; this structural feature permits to suppose ion-conductive and/or electrochemical properties of the title compound. The possible mechanism of the δ → γ phase transition is discussed on the basis of the crystal chemical analysis of the KCoPO4 polymorphs. The title compound orders magnetically at TN = 24.8 K.

20.
Nicotine Tob Res ; 23(6): 976-982, 2021 05 24.
Artículo en Inglés | MEDLINE | ID: mdl-33085765

RESUMEN

INTRODUCTION: Smoking behaviour shows seasonal variation, with cigarette consumption and youth smoking onset highest in summer and smoking-related web searches and sales of nicotine replacement products highest in winter. Variation in demand for clinical care and in outcomes has not been explored. AIMS AND METHODS: We measure seasonal variation in enrolments, total clinical visits, visits per enrolment, and treatment outcome (7-day abstinence at 6-month follow-up) from 2015 to 2018 in a large (n = 85 869) clinical cohort from 454 clinics across Ontario, Canada. We model seasonality using harmonic logistic and negative binomial regression. For individual-level outcomes, we adjust for variables, selected a priori, known to be associated with treatment use or outcomes. Data are nearly complete for 3 outcomes, but 6m abstinence is missing for 45% of participants. We use multiple imputation to adjust for missing data. RESULTS: All four outcomes showed significant seasonal variation (all p <.001). Total enrolments and visits were 20%-25% higher in January-April than in June-September. Visits per enrolment varied slightly, with lowest levels from May-July. Abstinence at 6 months was lowest among individuals enrolled from February-May and highest for those enrolled from July-November, with an absolute peak-trough difference of 4.3% (95% CI = 3.2% to 5.5%). CONCLUSIONS: There is meaningful seasonal variation in demand for, and outcomes of, smoking cessation treatment. Climate and weather may be indirectly responsible. Seasonal differences underscore the general importance of contextual factors in smoking cessation, may be useful in program promotion, and may explain some variability in outcomes in evaluation and research. IMPLICATIONS: Demand for tobacco cessation treatment and clinical outcomes vary seasonally. This underscores the importance of context in substance-related problems, and implies that some variability in research and evaluation results may be due to the time of year data were collected. Promotion efforts might usefully consider seasonal effects to smooth out demand and possibly improve outcomes.


Asunto(s)
Cese del Hábito de Fumar , Dispositivos para Dejar de Fumar Tabaco , Adolescente , Humanos , Ontario/epidemiología , Estaciones del Año , Fumar
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