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1.
Benef Microbes ; 15(2): 179-194, 2024 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-38350465

RESUMO

The objective of the study was to examine the impact of a multi-strain probiotic (MSP) on sleep, physical activity, and body composition changes. We used a randomised, double-blind, placebo-controlled approach with 70 healthy men and women (31.0 ± 9.5 years, 173.0 ± 10.4 cm, 73.9 ± 13.8 kg, 24.6 ± 3.5 kg/m2) supplemented daily with MSP (4 × 109 live cells Limosilactobacillus fermentum LF16, Lacticaseibacillus rhamnosus LR06, Lactiplantibacillus plantarum LP01, and Bifidobacterium longum 04; Probiotical S.p.A., Novara, Italy) or placebo (PLA). In response to supplementation (after 0, 2, 4, and 6 weeks of supplementation) and 3 weeks after stopping supplementation, participants had subjective (Pittsburgh Sleep Quality Index, PSQI) and objective sleep indicators, body composition, daily physical activity and resting hemodynamics assessed. Subjective sleep quality indicators using the PSQI (sleep latency, sleep disturbance, and global PSQI score) improved ( P < 0.05) at various time points with MSP supplementation. Systolic blood pressure in PLA increased ( P < 0.05) after 6 weeks of supplementation with no change in MSP. No changes ( P > 0.05) in sleep (hours asleep, minutes awake, number of times awake) or physical activity (step count, minutes of sedentary activity, total active minutes) metrics assessed by the wearable device were observed. Additionally, no changes in resting heart rate, diastolic blood pressure, and body composition were discerned. In conclusion, MSP supplementation improved the subjective ability to fall asleep faster and disturbances experienced during sleep, which resulted in improved overall sleep quality as assessed by the PSQI. No differences in other sleep indicators, physical activity, hemodynamics, and body composition were observed during or following MSP supplementation. Registered at clinicaltrials.gov: NCT05343533.


Assuntos
Composição Corporal , Exercício Físico , Hemodinâmica , Probióticos , Qualidade do Sono , Humanos , Probióticos/administração & dosagem , Masculino , Feminino , Método Duplo-Cego , Adulto , Exercício Físico/fisiologia , Hemodinâmica/efeitos dos fármacos , Adulto Jovem , Suplementos Nutricionais , Lacticaseibacillus rhamnosus/fisiologia
2.
Sci Rep ; 13(1): 9241, 2023 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-37286669

RESUMO

Familial hypercholesterolemia (FH) is characterized by high low-density lipoprotein cholesterol (LDL-C) levels and a high risk of early coronary heart disease. Structural alterations in the LDLR, APOB, and PCSK9 genes were not found in 20-40% of patients diagnosed using the Dutch Lipid Clinic Network (DCLN) criteria. We hypothesized that methylation in canonical genes could explain the origin of the phenotype in these patients. This study included 62 DNA samples from patients with a clinical diagnosis of FH according to the DCLN criteria, who previously tested negative for structural alterations in the canonical genes, and 47 DNA samples from patients with normal blood lipids (control group). All DNA samples were tested for methylation in the CpG islands of the three genes. The prevalence of FH relative to each gene was determined in both groups and the respective prevalence ratios (PRs) were calculated. The methylation analysis of APOB and PCSK9 was negative in both groups, showing no relationship between methylation in these genes and the FH phenotype. As the LDLR gene has two CpG islands, we analyzed each island separately. The analysis of LDLR-island1 showed PR = 0.982 (CI 0.33-2.95; χ2 = 0.001; p = 0.973), also suggesting no relationship between methylation and the FH phenotype. Analysis of LDLR-island2 showed a PR of 4.12 (CI 1.43-11.88; χ2 = 13,921; p = 0.00019), indicating a possible association between methylation on this island and the FH phenotype.


Assuntos
Hiperlipoproteinemia Tipo II , Pró-Proteína Convertase 9 , Humanos , Pró-Proteína Convertase 9/genética , Hiperlipoproteinemia Tipo II/diagnóstico , Fenótipo , HDL-Colesterol/genética , Apolipoproteínas B/genética , Regiões Promotoras Genéticas , Receptores de LDL/genética , Mutação
3.
Acta Crystallogr D Struct Biol ; 79(Pt 7): 569-584, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37326585

RESUMO

Understanding how structure and function meet to drive biological processes is progressively shifting the cryoEM field towards a more advanced analysis of macromolecular flexibility. Thanks to techniques such as single-particle analysis and electron tomography, it is possible to image a macromolecule in different states, information that can subsequently be extracted through advanced image-processing methods to build a richer approximation of a conformational landscape. However, the interoperability of all of these algorithms remains a challenging task that is left to users, preventing them from defining a single flexible workflow in which conformational information can be addressed by different algorithms. Therefore, in this work, a new framework integrated into Scipion is proposed called the Flexibility Hub. This framework automatically handles intercommunication between different heterogeneity software, simplifying the task of combining the software into workflows in which the quality and the amount of information extracted from flexibility analysis is maximized.


Assuntos
Algoritmos , Software , Microscopia Crioeletrônica/métodos , Processamento de Imagem Assistida por Computador/métodos , Conformação Molecular , Substâncias Macromoleculares/química
4.
Nat Commun ; 14(1): 154, 2023 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-36631472

RESUMO

The new developments in Cryo-EM Single Particle Analysis are helping us to understand how the macromolecular structure and function meet to drive biological processes. By capturing many states at the particle level, it is possible to address how macromolecules explore different conformations, information that is classically extracted through 3D classification. However, the limitations of classical approaches prevent us from fully understanding the complete conformational landscape due to the reduced number of discrete states accurately reconstructed. To characterize the whole structural spectrum of a macromolecule, we propose an extension of our Zernike3D approach, able to extract per-image continuous flexibility information directly from a particle dataset. Also, our method can be seamlessly applied to images, maps or atomic models, opening integrative possibilities. Furthermore, we introduce the ZART reconstruction algorithm, which considers the Zernike3D deformation fields to revert particle conformational changes during the reconstruction process, thus minimizing the blurring induced by molecular motions.


Assuntos
Algoritmos , Microscopia Crioeletrônica/métodos , Conformação Molecular , Estrutura Molecular , Substâncias Macromoleculares/química
5.
Faraday Discuss ; 240(0): 210-227, 2022 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-35861059

RESUMO

The number of maps deposited in public databases (Electron Microscopy Data Bank, EMDB) determined by cryo-electron microscopy has quickly grown in recent years. With this rapid growth, it is critical to guarantee their quality. So far, map validation has primarily focused on the agreement between maps and models. From the image processing perspective, the validation has been mostly restricted to using two half-maps and the measurement of their internal consistency. In this article, we suggest that map validation can be taken much further from the point of view of image processing if 2D classes, particles, angles, coordinates, defoci, and micrographs are also provided. We present a progressive validation scheme that qualifies a result validation status from 0 to 5 and offers three optional qualifiers (A, W, and O) that can be added. The simplest validation state is 0, while the most complete would be 5AWO. This scheme has been implemented in a website https://biocomp.cnb.csic.es/EMValidationService/ to which reconstructed maps and their ESI can be uploaded.


Assuntos
Processamento de Imagem Assistida por Computador , Microscopia Crioeletrônica/métodos , Microscopia Eletrônica
6.
Acta Crystallogr D Struct Biol ; 78(Pt 4): 410-423, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35362465

RESUMO

Cryo-electron microscopy (cryoEM) has become a well established technique to elucidate the 3D structures of biological macromolecules. Projection images from thousands of macromolecules that are assumed to be structurally identical are combined into a single 3D map representing the Coulomb potential of the macromolecule under study. This article discusses possible caveats along the image-processing path and how to avoid them to obtain a reliable 3D structure. Some of these problems are very well known in the community. These may be referred to as sample-related (such as specimen denaturation at interfaces or non-uniform projection geometry leading to underrepresented projection directions). The rest are related to the algorithms used. While some have been discussed in depth in the literature, such as the use of an incorrect initial volume, others have received much less attention. However, they are fundamental in any data-analysis approach. Chiefly among them, instabilities in estimating many of the key parameters that are required for a correct 3D reconstruction that occur all along the processing workflow are referred to, which may significantly affect the reliability of the whole process. In the field, the term overfitting has been coined to refer to some particular kinds of artifacts. It is argued that overfitting is a statistical bias in key parameter-estimation steps in the 3D reconstruction process, including intrinsic algorithmic bias. It is also shown that common tools (Fourier shell correlation) and strategies (gold standard) that are normally used to detect or prevent overfitting do not fully protect against it. Alternatively, it is proposed that detecting the bias that leads to overfitting is much easier when addressed at the level of parameter estimation, rather than detecting it once the particle images have been combined into a 3D map. Comparing the results from multiple algorithms (or at least, independent executions of the same algorithm) can detect parameter bias. These multiple executions could then be averaged to give a lower variance estimate of the underlying parameters.


Assuntos
Imageamento Tridimensional , Viés , Consenso , Microscopia Crioeletrônica/métodos , Imageamento Tridimensional/métodos , Reprodutibilidade dos Testes
7.
Arthropod Struct Dev ; 65: 101100, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34488068

RESUMO

According to all latest phylogenetic analyses, the taxon Pancrustacea embraces the crustaceans in the traditional sense and the hexapods. Members of the Pancrustacea for a long time have been known to display distinct similarities in the architecture of their brains. Here, we review recent progress and open questions concerning structural and functional communalities of selected higher integrative neuropils in the lateral protocerebrum of pancrustaceans, the mushroom bodies and hemiellipsoid bodies. We also discuss the projection neuron pathway which provides a distinct input channel to both mushroom and hemiellipsoid bodies from the primary chemosensory centers in the deutocerebrum. Neuronal characters are mapped on a current pancrustacean phylogeny in order to extract those characters that are part of the pancrustacean ground pattern. Furthermore, we summarize recent insights into the evolutionary transformation of mushroom body morphology across the Pancrustacea.


Assuntos
Corpos Pedunculados , Neurópilo , Vias Aferentes , Animais , Encéfalo , Filogenia
8.
Sci Rep ; 11(1): 13493, 2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34188159

RESUMO

The rate of the remodeling of the arterialized saphenous vein conduit limits the outcomes of coronary artery bypass graft surgery (CABG), which may be influenced by endothelial dysfunction. We tested the hypothesis that high stretch (HS) induces human saphenous vein endothelial cell (hSVEC) dysfunction and examined candidate underlying mechanisms. Our results showed that in vitro HS reduces NO bioavailability, increases inflammatory adhesion molecule expression (E-selectin and VCAM1) and THP-1 cell adhesion. HS decreases F-actin in hSVECs, but not in human arterial endothelial cells, and is accompanied by G-actin and cofilin's nuclear shuttling and increased reactive oxidative species (ROS). Pre-treatment with the broad-acting antioxidant N-acetylcysteine (NAC) supported this observation and diminished stretch-induced actin remodeling and inflammatory adhesive molecule expression. Altogether, we provide evidence that increased oxidative stress and actin cytoskeleton remodeling play a role in HS-induced saphenous vein endothelial cell dysfunction, which may contribute to predisposing saphenous vein graft to failure.


Assuntos
Actinas/metabolismo , Células Endoteliais/metabolismo , Estresse Oxidativo , Veia Safena/metabolismo , Estresse Mecânico , Humanos , Espécies Reativas de Oxigênio/metabolismo , Células THP-1
9.
Life Sci ; 278: 119646, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34048814

RESUMO

AIMS: SCN5A gene encodes the α-subunit of Nav1.5, mainly found in the human heart. SCN5A variants are the most common genetic alterations associated with Brugada syndrome (BrS). In rare cases, compound heterozygosity is observed; however, its functional consequences are poorly understood. We aimed to analyze the functional impact of de novo Nav1.5 mutations in compound heterozygosity in distinct alleles (G400R and T1461S positions) previously found in a patient with BrS. Moreover, we evaluated the potential benefits of quinidine to improve the phenotype of mutant Na+ channels in vitro. MATERIALS AND METHODS: The functional properties of human wild-type and Nav1.5 variants were evaluated using whole-cell patch-clamp and immunofluorescence techniques in transiently expressed human embryonic kidney (HEK293) cells. KEY FINDINGS: Both variants occur in the highly conservative positions of SCN5A. Although all variants were expressed in the cell membrane, a significant reduction in the Na+ current density (except for G400R alone, which was undetected) was observed along with abnormal biophysical properties, once the variants were expressed in homozygosis and heterozygosis. Interestingly, the incubation of transfected cells with quinidine partially rescued the biophysical properties of the mutant Na+ channel. SIGNIFICANCE: De novo compound heterozygosis mutations in SNC5A disrupt the Na+ macroscopic current. Quinidine could partially reverse the in vitro loss-of-function phenotype of Na+ current. Thus, our data provide, for the first time, a detailed biophysical characterization of dysfunctional Na+ channels linked to compound heterozygosity in BrS as well as the benefits of the pharmacological treatment using quinidine on the biophysical properties of Nav1.5.


Assuntos
Síndrome de Brugada/genética , Mutação com Perda de Função , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Sequência de Aminoácidos , Síndrome de Brugada/tratamento farmacológico , Síndrome de Brugada/metabolismo , Células HEK293 , Heterozigoto , Humanos , Mutação com Perda de Função/efeitos dos fármacos , Canal de Sódio Disparado por Voltagem NAV1.5/química , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Mutação Puntual/efeitos dos fármacos , Quinidina/farmacologia
10.
Chronobiol Int ; 38(8): 1135-1142, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33906520

RESUMO

Chronotype or diurnal preference is a questionnaire-based measure influenced both by circadian period and by the sleep homeostat. In order to further characterize the biological determinants of these measures, we used a hypothesis-free approach to investigate the association between the score of the morningness-eveningness questionnaire (MEQ) and the Munich chronotype questionnaire (MCTQ), as continuous variables, and volumetric measures of brain regions acquired by magnetic resonance imaging (MRI). Data were collected from the Baependi Heart Study cohort, based in a rural town in South-Eastern Brazil. MEQ and anatomical 1.5-T MRI scan data were available from 410 individuals, and MCTQ scores were available from a subset of 198 of them. The average MEQ (62.2 ± 10.6) and MCTQ (average MSFsc 201 ± 85 min) scores were suggestive of a previously reported strong general tendency toward morningness in this community. Setting the significance threshold at P > .002 to account for multiple comparisons, we observed a significant association between lower MEQ score (eveningness) and greater volume of the left anterior occipital sulcus (ß = -0.163, p = .001) of the occipital lobe. No significant associations were observed for MCTQ. This may reflect the smaller dataset for MCTQ, and/or the fact that MEQ, which asks questions about preferred timings, is more trait-like than the MCTQ, which asks questions about actual timings. The association between MEQ and a brain region dedicated to visual information processing is suggestive of the increasingly recognized fluidity in the interaction between visual and nonvisual photoreception and the circadian system, and the possibility that chronotype includes an element of masking.


Assuntos
Ritmo Circadiano , Vigília , Encéfalo/diagnóstico por imagem , Brasil , Humanos , Lobo Occipital/diagnóstico por imagem , Sono , Inquéritos e Questionários
11.
PLoS One ; 14(6): e0217814, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31185027

RESUMO

Individual variability in word generation is a product of genetic and environmental influences. The genetic effects on semantic verbal fluency were estimated in 1,735 participants from the Brazilian Baependi Heart Study. The numbers of exemplars produced in 60 s were broken down into time quartiles because of the involvement of different cognitive processes-predominantly automatic at the beginning, controlled/executive at the end. Heritability in the unadjusted model for the 60-s measure was 0.32. The best-fit model contained age, sex, years of schooling, and time of day as covariates, giving a heritability of 0.21. Schooling had the highest moderating effect. The highest heritability (0.17) was observed in the first quartile, decreasing to 0.09, 0.12, and 0.0003 in the following ones. Heritability for average production starting point (intercept) was 0.18, indicating genetic influences for automatic cognitive processes. Production decay (slope), indicative of controlled processes, was not significant. The genetic influence on different quartiles of the semantic verbal fluency test could potentially be exploited in clinical practice and genome-wide association studies.


Assuntos
Cognição , Estudo de Associação Genômica Ampla , Semântica , Comportamento Verbal , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
12.
Sci Rep ; 9(1): 4356, 2019 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-30867458

RESUMO

Cardiometabolic risk factors influence white matter hyperintensity (WMH) development: in metabolic syndrome (MetS), higher WMH load is often reported but the relationships between specific cardiometabolic variables, WMH load and cognitive performance are uncertain. We investigated these in a Brazilian sample (aged 50-85) with (N = 61) and without (N = 103) MetS. Stepwise regression models identified effects of cardiometabolic and demographic variables on WMH load (from FLAIR MRI) and verbal recall performance. WMH volume was greater in MetS, but verbal recall performance was not impaired. Age showed the strongest relationship with WMH load. Across all participants, systolic blood pressure (SBP) and fasting blood glucose were also contributors, and WMH volume was negatively associated with verbal recall performance. In non-MetS, higher HbA1c, SBP, and number of MetS components were linked to poorer recall performance while higher triglyceride levels appeared to be protective. In MetS only, these relationships were absent but education exerted a strongly protective effect on recall performance. Thus, results support MetS as a construct: the clustering of cardiometabolic variables in MetS alters their individual relationships with cognition; instead, MetS is characterised by a greater reliance on cognitive reserve mechanisms. In non-MetS, strategies to control HbA1c and SBP should be prioritised as these have the largest impact on cognition.


Assuntos
Cognição , Síndrome Metabólica/metabolismo , Síndrome Metabólica/patologia , Substância Branca/patologia , Substância Branca/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Biomarcadores , Doenças Cardiovasculares/complicações , Metabolismo Energético , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Síndrome Metabólica/complicações , Pessoa de Meia-Idade , Testes Neuropsicológicos , Fatores de Risco , Substância Branca/diagnóstico por imagem
13.
Acta Crystallogr F Struct Biol Commun ; 75(Pt 1): 19-32, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30605122

RESUMO

Single-particle analysis by electron microscopy is a well established technique for analyzing the three-dimensional structures of biological macromolecules. Besides its ability to produce high-resolution structures, it also provides insights into the dynamic behavior of the structures by elucidating their conformational variability. Here, the different image-processing methods currently available to study continuous conformational changes are reviewed.


Assuntos
Elétrons , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Imageamento Tridimensional/estatística & dados numéricos , Substâncias Macromoleculares/ultraestrutura , Microscopia Eletrônica/métodos , Proteínas/ultraestrutura , Algoritmos , Humanos , Substâncias Macromoleculares/química , Microscopia Eletrônica/instrumentação , Conformação Molecular , Simulação de Dinâmica Molecular , Análise de Componente Principal , Proteínas/química , Termodinâmica
14.
Insect Mol Biol ; 28(2): 264-276, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30375079

RESUMO

Odorant-binding proteins (OBPs) are essential molecular elements of the insect chemosensory system, which is composed of the antennae and the mouthpart palps (maxillary and labial). In this study, we have analysed the expression and the sensilla specificity of 14 OBP subtypes in the palps of the desert locust Schistocerca gregaria. The locust palps comprise only a low number of sensilla basiconica but a high number of sensilla chaetica. Employing a variety of approaches, we found that only a subset of the antennal OBP repertoire was expressed in both palp types. These OBPs were previously shown to be expressed either in sensilla basiconica or sensilla chaetica of the antennae. Comparing the expression pattern in the two chemosensory organs revealed similarities and differences; most remarkably, two OBP subtypes, OBP6 and OBP8, were found in both sensilla types on palps, whereas on the antennae they were solely expressed in one sensillum type. Together, the data indicate a differential, but partly overlapping, expression of OBPs in the two sensilla types of the palps. The differences in the expression pattern of OBP subtypes between antennae and palps might be indicative for distinct functions of the OBPs in the two chemosensory organs.


Assuntos
Gafanhotos/metabolismo , Proteínas de Insetos/metabolismo , Receptores Odorantes/metabolismo , Animais , Feminino , Masculino , Boca/metabolismo
15.
HNO ; 67(1): 36-44, 2019 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-30324556

RESUMO

BACKGROUND: Hearing-impairment can lead to a reduced quality of life and thus represents a vulnerability factor for mental disorders. OBJECTIVE: This study represents the first psychiatric analysis of subjective quality of life and depression in people with hearing-impairment in Germany. MATERIALS AND METHODS: The patient group included 30 hearing-impaired participants (27 women, 3 men) with a current or previous mental disorder and/or psychiatric/psychotherapeutic treatment (age: mean, M = 49.67 years; standard deviation, SD = 13.54 years). The control group consisted of 22 hearing-impaired participants (16 women, 6 men) without mental disorders or treatment (age: M = 52.41 years, SD = 17.30 years). Besides sociodemographic variables, we registered onset/extent of the various hearing-impairments and hearing aid provision. Both groups underwent extensive diagnostic assessment comprising subjective functional impairment (Sheehan Disability Scale, SDS), health-related quality of life (SF-36 Health Survey), and depressive symptoms (Beck Depression Inventory, BDI-II). RESULTS: Groups did not differ significantly in terms of sociodemographic variables such as age, gender, or intelligence. Participants of the patient group had a significantly greater subjective impairment, a lower quality of life, and more pronounced symptoms of depression. The invasiveness of the hearing aid (i. e., cochlear implant) as well as the timepoint of hearing-impairment onset (postlingually) appear to serve as vulnerability factors for mental health problems in this group. CONCLUSION: Our results indicate that besides delivering high-quality acoustic care, practitioners should continuously check patients' requirements for psychosocial treatment due to a loss of quality of life. The development of a specific psychotherapeutic treatment for hearing-impaired clients requires additional research focused on protective and vulnerability factors which may influence the emergence of mental disorders in these patients.


Assuntos
Depressão , Pessoas com Deficiência Auditiva/psicologia , Qualidade de Vida , Depressão/epidemiologia , Feminino , Alemanha , Auxiliares de Audição , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários
16.
Regen Eng Transl Med ; 4(2): 92-103, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30288396

RESUMO

To examine how the chemotactic agent stromal cell-derived factor-1alpha (SDF-1α) modulates the unique cellular milieu within rotator cuff muscle following tendon injury, we developed an injectable, heparin-based microparticle platform to locally present SDF-1α within the supraspinatus muscle following severe rotator cuff injury. SDF-1α loaded, degradable, N-desulfated heparin-based microparticles were fabricated, injected into a rat model of severe rotator cuff injury, and were retained for up to 7 days at the site. The resultant inflammatory cell and mesenchymal stem cell populations were analyzed compared to uninjured contralateral controls and, after 7 days, the fold-change in anti-inflammatory, M2-like macrophages (CD11b+CD68+CD163+, 4.3X fold-change) and mesenchymal stem cells (CD29+CD44+CD90+, 3.0X, respectively) was significantly greater in muscles treated with SDF-1α loaded microparticles than unloaded microparticles or injury alone. Our results indicate that SDF-1α loaded microparticles may be a novel approach to shift the cellular composition within the supraspinatus muscle and create a more pro-regenerative milieu, which may provide a platform to improve muscle repair following rotator cuff injury in the future.

17.
Phys Rev Lett ; 121(7): 077004, 2018 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-30169083

RESUMO

We present a soft x-ray angle-resolved photoemission spectroscopy study of overdoped high-temperature superconductors. In-plane and out-of-plane components of the Fermi surface are mapped by varying the photoemission angle and the incident photon energy. No k_{z} dispersion is observed along the nodal direction, whereas a significant antinodal k_{z} dispersion is identified for La-based cuprates. Based on a tight-binding parametrization, we discuss the implications for the density of states near the van Hove singularity. Our results suggest that the large electronic specific heat found in overdoped La_{2-x}Sr_{x}CuO_{4} cannot be assigned to the van Hove singularity alone. We therefore propose quantum criticality induced by a collapsing pseudogap phase as a plausible explanation for observed enhancement of electronic specific heat.

18.
Prog Neurobiol ; 161: 23-60, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29197652

RESUMO

Malacostracan crustaceans display a large diversity of sizes, morphs and life styles. However, only a few representatives of decapod taxa have served as models for analyzing crustacean olfaction, such as crayfish and spiny lobsters. Crustaceans bear multiple parallel chemosensory pathways represented by different populations of unimodal chemosensory and bimodal chemo- and mechanosensory sensilla on the mouthparts, the walking limbs and primarily on their two pairs of antennae. Here, we focus on the olfactory pathway associated with the unimodal chemosensory sensilla on the first antennal pair, the aesthetascs. We explore the diverse arrangement of these sensilla across malacostracan taxa and point out evolutionary transformations which occurred in the central olfactory pathway. We discuss the evolution of chemoreceptor proteins, comparative aspects of active chemoreception and the temporal resolution of crustacean olfactory system. Viewing the evolution of crustacean brains in light of energetic constraints can help us understand their functional morphology and suggests that in various crustacean lineages, the brains were simplified convergently because of metabolic limitations. Comparing the wiring of afferents, interneurons and output neurons within the olfactory glomeruli suggests a deep homology of insect and crustacean olfactory systems. However, both taxa followed distinct lineages during the evolutionary elaboration of their olfactory systems. A comparison with insects suggests their olfactory systems ö especially that of the vinegar fly ö to be superb examples for "economy of design". Such a comparison also inspires new thoughts about olfactory coding and the functioning of malacostracan olfactory systems in general.


Assuntos
Células Quimiorreceptoras/fisiologia , Crustáceos/anatomia & histologia , Condutos Olfatórios/fisiologia , Olfato/fisiologia , Animais , Condutos Olfatórios/citologia
19.
Int J Immunogenet ; 44(5): 219-224, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28815969

RESUMO

Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) molecule is expressed on T-lymphocyte membrane and negatively influences the antigen-presenting process. Reduced expression of CTLA-4 due to gene polymorphisms is associated with increased risk of autoimmune disorders, whose physiopathology is similar to that of post-transfusion red blood cell (RBC) alloimmunization. Our goal was to evaluate if polymorphisms of CTLA-4 gene that affect protein expression are associated with RBC alloimmunization. This was a case-control study in which 134 sickle cell disease (SCD) patients and 253 non-SCD patients were included. All patients were genotyped for the polymorphisms 49A/G and -318C/T of CTLA-4 gene. The genotype frequency of -318C/T differed significantly between alloimmunized and nonalloimmunized SCD patients, irrespective of clinical confounders (p = .016). SCD patients heterozygous for -318T allele presented higher risk of alloantibody development (OR: 5.4, CI: 1.15-25.6). In conclusion, the polymorphism -318C/T of CTLA-4 gene is associated with RBC alloimmunization among SCD patients. This highlights the role played by CTLA-4 on post-transfusion alloantibody development.


Assuntos
Anemia Falciforme/genética , Doenças Autoimunes/genética , Antígeno CTLA-4/genética , Eritrócitos/imunologia , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/imunologia , Anemia Falciforme/prevenção & controle , Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/patologia , Doenças Autoimunes/sangue , Doenças Autoimunes/imunologia , Doenças Autoimunes/patologia , Antígeno CTLA-4/imunologia , Eritrócitos/patologia , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Imunização/efeitos adversos , Isoanticorpos/imunologia , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Fatores de Risco , Linfócitos T/imunologia , Linfócitos T/patologia
20.
Phys Rev Lett ; 119(2): 026403, 2017 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-28753342

RESUMO

By combining bulk sensitive soft-x-ray angular-resolved photoemission spectroscopy and first-principles calculations we explored the bulk electron states of WTe_{2}, a candidate type-II Weyl semimetal featuring a large nonsaturating magnetoresistance. Despite the layered geometry suggesting a two-dimensional electronic structure, we directly observe a three-dimensional electronic dispersion. We report a band dispersion in the reciprocal direction perpendicular to the layers, implying that electrons can also travel coherently when crossing from one layer to the other. The measured Fermi surface is characterized by two well-separated electron and hole pockets at either side of the Γ point, differently from previous more surface sensitive angle-resolved photoemission spectroscopy experiments that additionally found a pronounced quasiparticle weight at the zone center. Moreover, we observe a significant sensitivity of the bulk electronic structure of WTe_{2} around the Fermi level to electronic correlations and renormalizations due to self-energy effects, previously neglected in first-principles descriptions.

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