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A growing body of theoretical and experimental evidence suggests that intramolecular epistasis is a major determinant of rates and patterns of protein evolution and imposes a substantial constraint on the evolution of novel protein functions. Here, we examine the role of intramolecular epistasis in the recurrent evolution of resistance to cardiotonic steroids (CTS) across tetrapods, which occurs via specific amino acid substitutions to the α-subunit family of Na,K-ATPases (ATP1A). After identifying a series of recurrent substitutions at two key sites of ATP1A that are predicted to confer CTS resistance in diverse tetrapods, we then performed protein engineering experiments to test the functional consequences of introducing these substitutions onto divergent species backgrounds. In line with previous results, we find that substitutions at these sites can have substantial background-dependent effects on CTS resistance. Globally, however, these substitutions also have pleiotropic effects that are consistent with additive rather than background-dependent effects. Moreover, the magnitude of a substitution's effect on activity does not depend on the overall extent of ATP1A sequence divergence between species. Our results suggest that epistatic constraints on the evolution of CTS-resistant forms of Na,K-ATPase likely depend on a small number of sites, with little dependence on overall levels of protein divergence. We propose that dependence on a limited number sites may account for the observation of convergent CTS resistance substitutions observed among taxa with highly divergent Na,K-ATPases (See S1 Text for Spanish translation).
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ATPasa Intercambiadora de Sodio-Potasio , Toxinas Biológicas , Secuencia de Aminoácidos , Sustitución de Aminoácidos/genética , Sodio/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/genéticaRESUMEN
Enhancers activate transcription through long-distance interactions with their cognate promoters within a particular subtopologically associated domain (sub-TAD). The TCRα enhancer (Eα) is located at the sub-TAD boundary between the TCRα and DAD1 genes and regulates transcription toward both sides in an â¼1-Mb region. Analysis of Eα activity in transcribing the unrearranged TCRα gene at the 5'-sub-TAD has defined Eα as inactive in CD4-CD8- thymocytes, active in CD4+CD8+ thymocytes, and strongly downregulated in CD4+ and CD8+ thymocytes and αß T lymphocytes. Despite its strongly reduced activity, Eα is still required for high TCRα transcription and expression of TCRαß in mouse and human T lymphocytes, requiring collaboration with distant sequences for such functions. Because VαJα rearrangements in T lymphocytes do not induce novel long-range interactions between Eα and other genomic regions that remain in cis after recombination, strong Eα connectivity with the 3'-sub-TAD might prevent reduced transcription of the rearranged TCRα gene. Our analyses of transcriptional enhancer dependence during T cell development and non-T lineage tissues at the 3'-sub-TAD revealed that Eα can activate the transcription of specific genes, even when it is inactive to transcribe the TCRα gene at the 5'-sub-TAD. Hence distinct requirements for Eα function are necessary at specific genes at both sub-TADs, implying that enhancers do not merely function as chromatin loop anchors that nucleate the formation of factor condensates to increase gene transcription initiated at their cognate promoters. The observed different regulated Eα activity for activating specific genes at its flanking sub-TADs may be a general feature for enhancers located at sub-TAD boundaries.
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Elementos de Facilitación Genéticos , Regulación de la Expresión Génica , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Animales , Diferenciación Celular/genética , Mapeo Cromosómico , Reordenamiento Génico de la Cadena alfa de los Receptores de Antígenos de los Linfocitos T , Sitios Genéticos , Humanos , Células Jurkat , Ratones , Ratones Noqueados , Ratones Transgénicos , Linfocitos T/inmunología , Linfocitos T/metabolismo , Timocitos/inmunología , Timocitos/metabolismoRESUMEN
The coordinated azido ligand has a variety of ways to establish intermolecular contacts whose nature is computationally analysed in this work on dimers of the [N3-Hg(CF3)] complex with different interactions involving only Nâ¯N contacts, or with an additional Hgâ¯N contact. The applied tools include the molecular electrostatic map of the monomer, an energy decomposition analysis (EDA), a topological AIM analysis of the electron density and the study of NCI (non-covalent interactions) isosurfaces. The interactions between two azido ligands are found to be weakly stabilizing (by 0.2 to 2.7 kcal mol-1), topology-dependent and require dispersion forces to complement orbital and electrostatic stabilization. Those interactions are supplemented by the formation of simultaneous Hgâ¯N secondary interactions by about -1 kcal mol-1, and by the ability of the monomer to simultaneously interact with several neighbours in the crystal structure.
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BACKGROUND: Artificial intelligence chatbots such as ChatGPT (OpenAI) have garnered excitement about their potential for delegating writing tasks ordinarily performed by humans. Many of these tasks (eg, writing recommendation letters) have social and professional ramifications, making the potential social biases in ChatGPT's underlying language model a serious concern. OBJECTIVE: Three preregistered studies used the text analysis program Linguistic Inquiry and Word Count to investigate gender bias in recommendation letters written by ChatGPT in human-use sessions (N=1400 total letters). METHODS: We conducted analyses using 22 existing Linguistic Inquiry and Word Count dictionaries, as well as 6 newly created dictionaries based on systematic reviews of gender bias in recommendation letters, to compare recommendation letters generated for the 200 most historically popular "male" and "female" names in the United States. Study 1 used 3 different letter-writing prompts intended to accentuate professional accomplishments associated with male stereotypes, female stereotypes, or neither. Study 2 examined whether lengthening each of the 3 prompts while holding the between-prompt word count constant modified the extent of bias. Study 3 examined the variability within letters generated for the same name and prompts. We hypothesized that when prompted with gender-stereotyped professional accomplishments, ChatGPT would evidence gender-based language differences replicating those found in systematic reviews of human-written recommendation letters (eg, more affiliative, social, and communal language for female names; more agentic and skill-based language for male names). RESULTS: Significant differences in language between letters generated for female versus male names were observed across all prompts, including the prompt hypothesized to be neutral, and across nearly all language categories tested. Historically female names received significantly more social referents (5/6, 83% of prompts), communal or doubt-raising language (4/6, 67% of prompts), personal pronouns (4/6, 67% of prompts), and clout language (5/6, 83% of prompts). Contradicting the study hypotheses, some gender differences (eg, achievement language and agentic language) were significant in both the hypothesized and nonhypothesized directions, depending on the prompt. Heteroscedasticity between male and female names was observed in multiple linguistic categories, with greater variance for historically female names than for historically male names. CONCLUSIONS: ChatGPT reproduces many gender-based language biases that have been reliably identified in investigations of human-written reference letters, although these differences vary across prompts and language categories. Caution should be taken when using ChatGPT for tasks that have social consequences, such as reference letter writing. The methods developed in this study may be useful for ongoing bias testing among progressive generations of chatbots across a range of real-world scenarios. TRIAL REGISTRATION: OSF Registries osf.io/ztv96; https://osf.io/ztv96.
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Inteligencia Artificial , Sexismo , Humanos , Femenino , Masculino , Revisiones Sistemáticas como Asunto , Lenguaje , LingüísticaRESUMEN
BACKGROUND: In tissues and organisms, the coordination of neighboring cells is essential to maintain their properties and functions. Therefore, knowing which cells are adjacent is crucial to understand biological processes that involve physical interactions among them, e.g. cell migration and proliferation. In addition, some signaling pathways, such as Notch or extrinsic apoptosis, are highly dependent on cell-cell communication. While this is straightforward to obtain from membrane images, nuclei labelling is much more ubiquitous for technical reasons. However, there are no automatic and robust methods to find neighboring cells based only on nuclear markers. RESULTS: In this work, we describe Nfinder, a method to assess the cell's local neighborhood from images with nuclei labeling. To achieve this goal, we approximate the cell-cell interaction graph by the Delaunay triangulation of nuclei centroids. Then, links are filtered by automatic thresholding in cell-cell distance (pairwise interaction) and the maximum angle that a pair of cells subtends with shared neighbors (non-pairwise interaction). We systematically characterized the detection performance by applying Nfinder to publicly available datasets from Drosophila melanogaster, Tribolium castaneum, Arabidopsis thaliana and C. elegans. In each case, the result of the algorithm was compared to a cell neighbor graph generated by manually annotating the original dataset. On average, our method detected 95% of true neighbors, with only 6% of false discoveries. Remarkably, our findings indicate that taking into account non-pairwise interactions might increase the Positive Predictive Value up to + 11.5%. CONCLUSION: Nfinder is the first robust and automatic method for estimating neighboring cells in 2D and 3D based only on nuclear markers and without any free parameters. Using this tool, we found that taking non-pairwise interactions into account improves the detection performance significantly. We believe that using our method might improve the effectiveness of other workflows to study cell-cell interactions from microscopy images. Finally, we also provide a reference implementation in Python and an easy-to-use napari plugin.
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Arabidopsis , Drosophila melanogaster , Animales , Caenorhabditis elegans , Microscopía/métodos , Núcleo Celular/metabolismo , Algoritmos , Procesamiento de Imagen Asistido por Computador/métodosRESUMEN
With today's pace of rapid technological advancement, many patient issues in modern medicine are increasingly solvable by mobile app solutions, which also have the potential to transform how clinical research is conducted. However, many critical challenges in the app development process impede bringing these translational technologies to patients, caused in large part by the lack of knowledge among clinicians and biomedical researchers of "what it takes" to design, develop, and maintain a successful medical app. Indeed, problems requiring mobile app solutions are often nuanced, requiring more than just clinical expertise, and issues such as the cost and effort required to develop and maintain a well-designed, sustainable, and scalable mobile app are frequently underestimated. To bridge this skill set gap, we established an academic unit of designers, software engineers, and scientists that leverage human-centered design methodologies and multi-disciplinary collaboration to develop clinically viable smartphone apps. In this report, we discuss major misconceptions clinicians and biomedical researchers often hold regarding medical app development, the steps we took to establish this unit to address these issues and the best practices and lessons learned from successfully ideating, developing, and launching medical apps. Overall, this report will serve as a blueprint for clinicians and biomedical researchers looking to better benefit their patients or colleagues via medical mobile apps.
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Aplicaciones Móviles , Médicos , Humanos , Encuestas y Cuestionarios , PacientesRESUMEN
Since gold is located well beyond the oxo wall, chemical species with terminal Au-N and Au-O units are extremely rare and limited to low coordination numbers. We report here that these unusual units can be trapped within a suitable organometallic frame. Thus, the terminal auronitrene and auroxyl derivatives [(CF3 )3 AuN]- and [(CF3 )3 AuO]- were identified as local minima by calculation. These open-shell, high-energy ions were experimentally detected by tandem mass spectrometry (MS2 ): They respectively arise by N2 or NO2 dissociation from the corresponding precursor species [(CF3 )3 Au(N3 )]- and [(CF3 )3 Au(ONO2 )]- in the gas phase. Together with the known fluoride derivative [(CF3 )3 AuF]- , they form an interesting series of isoleptic and alloelectronic complexes of the highly acidic organogold(iii) moiety (CF3 )3 Au with singly charged anions X- of the most electronegative elements (X=F, O, N). Ligand-field inversion in all these [(CF3 )3 AuX]- species results in the localization of unpaired electrons at the N and O atoms.
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BACKGROUND: At least 5%-10% of malignancies occur secondary to an underlying cancer predisposition syndrome (CPS). For these families, cancer surveillance is recommended with the goal of identifying malignancy earlier, in a presumably more curable form. Surveillance protocols, including imaging studies, bloodwork, and procedures, can be complex and differ based on age, gender, and syndrome, which adversely affect adherence. Mobile health (mHealth) applications (apps) have been utilized in oncology and could help to facilitate adherence to cancer surveillance protocols. METHODS: Applying a user-centered mobile app design approach, patients with a CPS and/or primary caregivers were interviewed to identify current methods for care management and barriers to compliance with recommended surveillance protocols. Broad themes from these interviews informed the design of the mobile app, HomeTown, which was subsequently evaluated by usability experts. The design was then converted into software code in phases, evaluated by patients and caregivers in an iterative fashion. User population growth and app usage data were assessed. RESULTS: Common themes identified included general distress surrounding surveillance protocol scheduling and results, difficulty remembering medical history, assembling a care team, and seeking resources for self-education. These themes were translated into specific functional app features, including push reminders, syndrome-specific surveillance recommendations, ability to annotate visits and results, storage of medical histories, and links to reliable educational resources. CONCLUSIONS: Families with CPS demonstrate a desire for mHealth tools to facilitate adherence to cancer surveillance protocols, reduce related distress, relay medical information, and provide educational resources. HomeTown may be a useful tool for engaging this patient population.
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Aplicaciones Móviles , Neoplasias , Telemedicina , Humanos , Síndrome , Oncología Médica , Susceptibilidad a EnfermedadesRESUMEN
The geometrical parameters and the bonding in [D···X···D]+ halonium compounds, where D is a Lewis base with N as the donor atom and X is Cl, Br, or I, have been investigated through a combined structural and computational study. Cambridge Structural Database (CSD) searches have revealed linear and symmetrical [D···X···D]+ frameworks with neutral donors. By means of density functional theory (DFT), molecular electrostatic potential (MEP), and energy decomposition analyses (EDA) calculations, we have studied the effect of various halogen atoms (X) on the [D···X···D]+ framework, the effect of different nitrogen-donor groups (D) attached to an iodonium cation (X = I), and the influence of the electron density alteration on the [D···I···D]+ halonium bond by variation of the R substituents at the N-donor upon the symmetry, strength, and nature of the interaction. The physical origin of the interaction arises from a subtle interplay between electrostatic and orbital contributions (σ-hole bond). Interaction energies as high as 45 kcal/mol suggest that halonium bonds can be exploited for the development of novel halonium transfer agents, in asymmetric halofunctionalization or as building blocks in supramolecular chemistry.
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BACKGROUND High altitude increases sunlight exposure, resulting in actinic keratosis, which predisposes people to skin cancer. The dermoscopy procedure evaluates keratotic and pigmented skin changes. This study aimed to describe the clinical and dermoscopic actinic changes in the lips of 25 indigenous children living at high altitude in Ecuador. MATERIAL AND METHODS An observational study was conducted in a public school in the Andes region of Ecuador (August-November 2019). Twenty-five children, males and females, age 5-15 years were assessed by complete physical examination, digital dermoscopic photographs, and punch biopsies. Descriptive statistics and Fisher's exact test were used to summarize and analyze the data. RESULTS We included 17 (68%) boys and 8 (32%) girls with a mean age of 9.8±2.0 years. Clinical lips findings reported desquamation [52% Upper Lip (UL); 40% Lower Lip (LL)], fissuring (8% UL; 8% LL), scabs (8% UL; 8% LL), and discoloration (40% UL; 20% LL). Dermoscopic features included a white-yellow lip color (24% UL; p=0.02). The main morphologic pattern of blood vessels was monomorphic (88% UL; p<0.001), polymorphous (60% LL; p<0.001), dotted pattern (64% UL; 28% LL; p=0.02), and linear-irregular (32% UL; 72% LL; p=0.01). Girls had radiating white structures on UL (p=0.025), while boys presented white structureless areas (UL 63.6%; LL 77.8%; p=0.032). No differences in dermoscopic findings were observed according to Fitzpatrick scale score (FSS). Punch biopsies showed no indications of actinic cheilitis. CONCLUSIONS Dermoscopic features in indigenous children living in high altitudes were related to actinic damage, but histopathological findings were negative.
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Queratosis Actínica , Neoplasias Cutáneas , Masculino , Femenino , Humanos , Niño , Preescolar , Adolescente , Labio , Altitud , Ecuador , Neoplasias Cutáneas/patología , Queratosis Actínica/diagnóstico , Queratosis Actínica/patologíaRESUMEN
Gigantism results when one lineage within a clade evolves extremely large body size relative to its small-bodied ancestors, a common phenomenon in animals. Theory predicts that the evolution of giants should be constrained by two tradeoffs. First, because body size is negatively correlated with population size, purifying selection is expected to be less efficient in species of large body size, leading to increased mutational load. Second, gigantism is achieved through generating a higher number of cells along with higher rates of cell proliferation, thus increasing the likelihood of cancer. To explore the genetic basis of gigantism in rodents and uncover genomic signatures of gigantism-related tradeoffs, we assembled a draft genome of the capybara (Hydrochoerus hydrochaeris), the world's largest living rodent. We found that the genome-wide ratio of nonsynonymous to synonymous mutations (ω) is elevated in the capybara relative to other rodents, likely caused by a generation-time effect and consistent with a nearly neutral model of molecular evolution. A genome-wide scan for adaptive protein evolution in the capybara highlighted several genes controlling postnatal bone growth regulation and musculoskeletal development, which are relevant to anatomical and developmental modifications for an increase in overall body size. Capybara-specific gene-family expansions included a putative novel anticancer adaptation that involves T-cell-mediated tumor suppression, offering a potential resolution to the increased cancer risk in this lineage. Our comparative genomic results uncovered the signature of an intragenomic conflict where the evolution of gigantism in the capybara involved selection on genes and pathways that are directly linked to cancer.
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Evolución Biológica , Tamaño Corporal/genética , Genoma , Roedores/genética , Animales , Femenino , Crecimiento/genética , Familia de Multigenes , Neoplasias/genética , Roedores/crecimiento & desarrolloRESUMEN
The degree of interpenetration of the van der Waals crusts of two atoms, represented by a penetration index, is defined to better quantify the meaning of the nonbonding contact distances between two atoms, which should allow us to compare different atom pairs on the same footing. The structural trends of the intermolecular contacts between the tetramethylammonium cation (TMA) and halogen atoms are reviewed, and a computational study of model X···TMA ion pairs (X = F, Cl, Br, I, Au) is presented. The results disclose two energy minima, in each of which the anion simultaneously interacts with three hydrogen atoms. The bonding mechanisms in the two cases are discussed based on the results of the tools of the trade that provide a consistent picture in which a distribution of charges significantly varies not only around each different atom but is also strongly dependent on the distance to the central N atom. This behavior, together with some non-negligible covalent character of the interionic interaction, is not predicted from a single-molecular electrostatic potential map of the TMA cation.
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PRIMARY OBJECTIVE: During the last decade, studies using anodal transcranial Direct Current Stimulation (atDCS) have yielded promising results in patients with aphasia. The main aim of the present pilot study was to assess the effects of combined atDCS over the left posterior perisylvian region and behavioral naming training on the behavioral outcomes of language comprehension and production of patients with post-stroke aphasia. RESEARCH DESIGN: A 2 × 2 quasi-experimental design was conducted, optimal to compare changes after treatment in experimental versus control group. METHODS AND PROCEDURES: Ten patients with post-stroke aphasia were enrolled in this study: half received atDCS on the left posterior perisylvian region while they underwent a 2-week behavioral naming training. The other half received sham stimulation. The outcomes were measured using the abbreviated form of the Boston Diagnostic Aphasia Examination and analyzed using ANOVAs. MAIN OUTCOMES AND RESULTS: Both groups improved their performance in Oral comprehension, Narrative writing and Language Competence Index, but only those that received anodal tDCS presented better results in the Naming category after the treatment. CONCLUSIONS: AtDCS on the left posterior perisylvian area seems to be a promising tool for boosting the outcomes of behavioral naming therapy in patients with post-stroke aphasia.
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Afasia , Estimulación Transcraneal de Corriente Directa , Afasia/etiología , Afasia/terapia , Humanos , Lenguaje , Pruebas del Lenguaje , Proyectos Piloto , Estimulación Transcraneal de Corriente Directa/métodosRESUMEN
LiCH3 and LiCH2 CH3 react with the complex [Mo2 (H)2 (µ-AdDipp2 )2 (thf)2 ] (1â thf) with coordination of two molecules of LiCH2 R (R=H, CH3 ) and formation of complexes [Mo2 {µ-HLi(thf)CH2 R}2 (AdDipp2 )2 ], 5â LiCH3 and 5â LiCH2 CH3 , respectively (AdDipp2 =HC(NDipp)2 ; Dipp=2,6-i Pr2 C6 H3 ; thf=C4 H8 O). Due to steric hindrance, only one molecule of LiC6 H5 adds to 1â thf generating the complex [Mo2 (H){µ-HLi(thf)C6 H5 }(µ-AdDipp2 )2 ], (4â LiC6 H5 ). Computational studies disclose the existence of five-center six-electron bonding within the H-Moâ£Mo-C-Li metallacycles, with a mostly covalent H-Moâ£Mo-C group and predominantly ionic Li-C and Li-H interactions. However, the latter bonds exhibit non-negligible covalency, as indicated by X-ray, computational data and the large one-bond 6,7 Li,1 H and 6,7 Li,13 C NMR coupling constants found for the three-atom H-Li-C chains. By contrast, the phenyl group in 4â LiC6 H5 coordinates in an η2 fashion to the lithium atom through the ipso and one of the ortho carbon atoms.
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The reactions of LiAlH4 as the source of LiH with complexes that contain (H)Moâ£Mo and (H)Moâ£Mo(H) cores stabilized by the coordination of bulky AdDipp2 ligands result in the respective coordination of one and two molecules of (thf)LiH, with the generation of complexes exhibiting one and two HLi(thf)H ligands extending across the Moâ£Mo bond (AdDipp2 = HC(NDipp)2; Dipp = 2,6-iPr2C6H3; thf = tetrahydrofuran, C4H8O). A theoretical study reveals the formation of Mo-H-Li three-center-two-electron bonds, supplemented by the coordination of the Moâ£Mo bond to the Li ion. Attempts to construct a [Mo2{HLi(thf)H}3(AdDipp2)] molecular architecture led to spontaneous trimerization and the formation of a chiral, hydride-rich Mo6Li9H18 supramolecular organization that is robust enough to withstand the substitution of lithium-solvating molecules of tetrahydrofuran by pyridine or 4-dimethylaminopyridine.
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This contribution focuses on complex [Mo2 (H)2 (µ-AdDipp2 )2 ] (1) and tetrahydrofuran and pyridine adducts [Mo2 (H)2 (µ-AdDipp2 )2 (L)2 ] (1â thf and 1â py), which contain a trans-(H)Moâ£Mo(H) core (AdDipp2 =HC(NDipp2 )2 ; Dipp=2,6-iPr2 C6 H3 ). Computational studies provide insights into the coordination and electronic characteristics of the central trans-Mo2 H2 unit of 1, with four-coordinate, fourteen-electron Mo atoms and ϵ-agostic interactions with Dipp methyl groups. Small size C- and N-donors give rise to related complexes 1â L but only one molecule of P-donors, for example, PMe3 , can bind to 1, causing one of the hydrides to form a three-centered, two-electron (3c-2e) Mo-HâMo bond (2â PMe3 ). A DFT analysis of the terminal and bridging hydride coordination to the Moâ£Mo bond is also reported, along with reactivity studies of the Mo-H bonds of these complexes. Reactions investigated include oxidation of 1â thf by silver triflimidate, AgNTf2 , to afford a monohydride [Mo2 (µ-H)(µ-NTf2 )(µ-AdDipp2 )2 ] (4), with an O,O'-bridging triflimidate ligand.
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In spite of the highly ionic character of most lithium-element bonds, the bonding within Li2X2 rings presents similarities with that found in analogous transition metal systems. They obey simple framework electron counting rules that allow us to predict whether they will form a regular ring or a squeezed one with short Li-Li or X-X distances. A combined computational and structural database analysis discloses the orbital conditions that determine the framework electron counting rules. These systems probe the borderline between the covalent and ionic bonding models since, paradoxically, a non-negligible covalent contribution of the two Li atoms (formally Li+ ions in the ionic model) to the Li-X framework bonding favors them approaching each other within bonding distance.
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In anesthesia automation, one of the main important issues is the availability of a reliable measurement of the depth of consciousness level (hypnosis) of the patient. According to this value, the hypnotic drug dosage can be adequately calculated. One of the most studied hypnosis indexes is the bispectral index (BIS). In this article we analyzed an alternative called patient state index (PSI). The objectives of this study are, first, to validate the accuracy of the PSI describing the hypnosis level during the maintenance phase of general anesthesia, by comparing with the BIS and, second, to model the relationship between propofol infusion rate and PSI values, obtained from a SEDLine monitor. For this, real data from patients undergoing general anesthesia simultaneously monitored with both BIS and PSI signals was used. Results obtained are interesting for a correct interpretation of PSI signal in clinical practice.
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Anestésicos Intravenosos , Propofol , Anestesia General , Electroencefalografía , Humanos , Monitoreo IntraoperatorioRESUMEN
In the present study we used the event-related brain potentials (ERP) technique and eLORETA (exact low-resolution electromagnetic tomography) method in order to characterize and compare the performance and the spatiotemporal pattern of the brain electrical activity related to the immediate episodic retrieval of information (words) that is being learned relative to delayed episodic retrieval twenty-minutes later. For this purpose, 16 young participants carried out an old/new word recognition task with source memory (word colour). The task included an immediate memory phase (with three study-test blocks) followed (20 min later) by a delayed memory phase with one test block. The behavioural data showed progressive learning and consolidation of the information (old words) during the immediate memory phase. The ERP data to correctly identified old words for which the colour was subsequently recollected (H/H) compared to the correctly rejected new words (CR) showed: (1) a significant more positive-going potential in the 500-675 ms post-stimulus interval (parietal old/new effect, related to recollection), and (2) a more negative-going potential in the 950-1850 ms interval (LPN effect, related to retrieval and post-retrieval processes). The eLORETA data also revealed that the successful recognition of old words (and probably retrieval of their colour) was accompanied by activation of (1) left medial temporal (parahippocampal gyrus) and parietal regions involved in the recollection in both memory phases, and (2) prefrontal regions and the superior temporal gyrus (in the immediate and delayed memory phases respectively) involved in monitoring, evaluating and maintaining the retrieval products. These findings indicate that episodic memory retrieval depends on a network involving medial temporal lobe and frontal, parietal and temporal neocortical structures. That network was involved in immediate and delayed memory retrieval and during the course of memory consolidation, with greater activation of some nodes (mobilization of more processing resources) for the delayed respect to the immediate retrieval condition.
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Encéfalo/fisiología , Potenciales Evocados/fisiología , Memoria Episódica , Recuerdo Mental/fisiología , Reconocimiento en Psicología/fisiología , Adolescente , Femenino , Humanos , Aprendizaje/fisiología , Masculino , Consolidación de la Memoria/fisiología , Giro Parahipocampal/fisiología , Lóbulo Parietal/fisiología , Corteza Prefrontal/fisiología , Lóbulo Temporal/fisiología , Adulto JovenRESUMEN
After briefly reviewing the applications of the coordination ability indices proposed earlier for anions and solvents toward transition metals and lanthanides, a new analysis of crystal structures is applied now to a much larger number of coordinating species: anions (including those that are present in ionic solvents), solvents, amino acids, gases, and a sample of neutral ligands. The coordinating ability towards s-block elements is now also considered. The effect of several factors on the coordinating ability will be discussed: (a)â the charge of an anion, (b)â the chelating nature of anions and solvents, (c)â the degree of protonation of oxo-anions, carboxylates and amino carboxylates, and (d)â the substitution of hydrogen atoms by methyl groups in NH3 , ethylenediamine, benzene, ethylene, pyridine and aldehydes. Hit parades of solvents and anions most commonly used in the areas of transition metal, s-block and lanthanide chemistry are deduced from the statistics of their presence in crystal structures.