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1.
J Surg Res ; 298: 36-40, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38552588

RESUMO

INTRODUCTION: Readmissions after a traumatic brain injury (TBI) can have severe impacts on long-term health outcomes as well as rehabilitation. The aim of this descriptive study was to analyze the Nationwide Readmissions Database to determine possible risk factors associated with readmission for patients who previously sustained a TBI. METHODS: This retrospective study used data from the Nationwide Readmissions Database to explore gender, age, injury severity score, comorbidities, index admission hospital size, discharge disposition of the patient, and cause for readmission for adults admitted with a TBI. Multivariable logistic regression was used to assess likelihood of readmission. RESULTS: There was a readmission rate of 28.7% (n = 31,757) among the study population. The primary cause of readmission was either subsequent injury or sequelae of the original injury (n = 8825; 29%) followed by circulatory (n = 5894; 19%) and nervous system issues (n = 2904; 9%). There was a significantly higher risk of being readmitted in males (Female odds ratio: 0.87; confidence interval [0.851-0.922), older patients (65-79: 32.3%; > 80: 37.1%), patients with three or more comorbidities (≥ 3: 32.9%), or in patients discharged to a skilled nursing facility/intermediate care facility/rehab (SNF/ICF/Rehab odds ratio: 1.55; confidence interval [0.234-0.262]). CONCLUSIONS: This study demonstrates a large proportion of patients are readmitted after sustaining a TBI. A significant number of patients are readmitted for subsequent injuries, circulatory issues, nervous system problems, and infections. Although readmissions cannot be completely avoided, defining at-risk populations is the first step of understanding how to reduce readmissions.


Assuntos
Lesões Encefálicas Traumáticas , Bases de Dados Factuais , Readmissão do Paciente , Humanos , Masculino , Readmissão do Paciente/estatística & dados numéricos , Feminino , Lesões Encefálicas Traumáticas/epidemiologia , Lesões Encefálicas Traumáticas/terapia , Estudos Retrospectivos , Pessoa de Meia-Idade , Adulto , Idoso , Estados Unidos/epidemiologia , Bases de Dados Factuais/estatística & dados numéricos , Fatores de Risco , Idoso de 80 Anos ou mais , Adulto Jovem , Adolescente , Comorbidade
2.
Cult Health Sex ; : 1-16, 2023 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-37740584

RESUMO

This paper describes the strategies used by Aboriginal young people to build positive relationships and sexual wellbeing. It does so to counter the risk-focussed narratives present in much existing research and to showcase the resourcefulness of Aboriginal young people. We used peer-interview methods to collect qualitative data from 52 Aboriginal young people living in western Sydney, Australia. Participants reported a strong desire to stay safe and healthy in their sexual relationships and to achieve this they relied heavily on oral communication and yarning strategies. Participants viewed communication as a way to gain or give advice (about bodies, infections, pregnancy, relationships); to assess the acceptability and safety of potential partners; to negotiate consent with partners; to build positive relationships; and to get themselves out of unhealthy relationships. Participants also discussed 'self-talk' as a strategy for building sexual wellbeing, referring to narratives of self-respect and pride in culture as important in establishing Aboriginal young people's positive views of self and as deserving of respectful and safe sexual relationships. These findings suggest that future programmes and interventions based on yarning could be well-regarded, given it is a cultural form of pedagogy and a strategy Aboriginal young people already use to build positive relationships and identities.

3.
Soft Matter ; 18(44): 8476-8485, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36317698

RESUMO

E-skins consisting of soft pressure sensors are enabling technology for soft robots, bio-integrated devices, and deformable touch panels. A well-known bottleneck of capacitive pressure sensors (CPS) is the drastic decay in sensitivity with increasing pressure. To overcome this challenge, we have invented a hybrid-response pressure sensor (HRPS) that exhibits both the piezoresistive and piezocapacitive effects intrinsic to a highly porous nanocomposite (PNC) with carbon nanotube (CNT) dopants. The HRPS is constructed with two conductive electrodes sandwiching a laminated PNC and a stiff dielectric layer. We have simplified the hybrid response into a parallel resistor-capacitor circuit, whose output depends on the AC (alternating current) frequency used for the capacitance measurement. Herein, through theoretical analysis, we discover a dimensionless parameter that governs the frequency responses of the HRPS. The master curve is validated through experiments on the HRPS with various doping ratios, subject to different compressive strains, under diverse AC frequencies. In addition, the relative contribution of piezoresistive and piezocapacitive mechanisms are also found to vary with the three parameters. Based on this experimentally validated theory, we establish a very practical guideline for selecting the optimal AC frequency for the capacitance measurement of HRPSs.

4.
J Biomol NMR ; 74(1): 95-109, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31915980

RESUMO

NMR spectroscopy provides a powerful approach for the characterisation of chemical exchange and molecular interactions by analysis of series of experiments acquired over the course of a titration measurement. The appearance of NMR resonances undergoing chemical exchange depends on the frequency difference relative to the rate of exchange, and in the case of one-dimensional experiments chemical exchange regimes are well established and well known. However, two-dimensional experiments present additional complexity, as at least one additional frequency difference must be considered. Here we provide a systematic classification of chemical exchange regimes in two-dimensional NMR spectra. We highlight important differences between exchange in HSQC and HMQC experiments, that on a practical level result in more severe exchange broadening in HMQC spectra, but show that complementary alternatives to the HMQC are available in the form of HZQC and HDQC experiments. We present the longitudinal relaxation optimised SOFAST-H(Z/D)QC experiment for the simultaneous acquisition of sensitivity-enhanced HZQC and HDQC spectra, and the longitudinal and transverse relaxation optimised BEST-ZQ-TROSY for analysis of large molecular weight systems. We describe the application of these experiments to the characterisation of the interaction between the Hsp90 N-terminal domain and a small molecule ligand, and show that the independent analysis of HSQC, HMQC, HZQC and HDQC experiments provides improved confidence in the fitted dissociation constant and dissociation rate. Joint analysis of such data may provide improved sensitivity to detect and analyse more complex multi-state interaction mechanisms such as induced fit or conformational selection.


Assuntos
Algoritmos , Ressonância Magnética Nuclear Biomolecular , Teoria Quântica , Proteínas de Choque Térmico HSP90/química , Proteínas de Choque Térmico HSP90/metabolismo , Ligantes , Ligação Proteica , Domínios Proteicos
5.
Int J Mol Sci ; 21(15)2020 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-32722166

RESUMO

Over the past decade intrinsically disordered proteins (IDPs) have emerged as a biologically important class of proteins, many of which are of therapeutic relevance. Here, we investigated the interactions between a model IDP system, tau K18, and nine literature compounds that have been reported as having an effect on tau in order to identify a robust IDP-ligand system for the optimization of a range of biophysical methods. We used NMR, surface plasmon resonance (SPR) and microscale thermophoresis (MST) methods to investigate the binding of these compounds to tau K18; only one showed unambiguous interaction with tau K18. Several near neighbors of this compound were synthesized and their interactions with tau K18 characterized using additional NMR methods, including 1D ligand-observed NMR, diffusion-ordered spectroscopy (DOSY) and 19F NMR. This study demonstrates that it is possible to detect and characterize IDP-ligand interactions using biophysical methods. However, care must be taken to account for possible artefacts, particularly the impact of compound solubility and where the protein has to be immobilized.


Assuntos
Proteínas Intrinsicamente Desordenadas/química , Simulação de Acoplamento Molecular , Proteínas tau/química , Humanos , Ligantes , Ressonância Magnética Nuclear Biomolecular
6.
J Surg Res ; 235: 16-21, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30691789

RESUMO

BACKGROUND: There is limited data pertaining to the triage and transportation of patients with penetrating trauma in rural states. Large urban trauma centers have found rapid transport to be beneficial even when done by nonemergency medical staff. However, there is limited application to a rural state with only a single level 1 trauma center. MATERIALS AND METHODS: This a retrospective observational study of 854 trauma patients transported by helicopter emergency services between 2009 and 2015 to the state's only level 1 trauma center. RESULTS: After excluding patients with other injuries or lack of data, 854 patients underwent final analysis. Compared with penetrating trauma, blunt trauma had a significantly different chance of survival (92.0% versus 81.2%, P = 0.002) and a significantly different injury severity score (17 ± 12 versus 12 ± 9, P = 0.002). After controlling for blunt injuries, age, gender, injury severity score, tachycardia, tachypnea, hypotension, glasgow coma scale, and dispatch to hospital arrival time in multivariate analysis, blunt trauma had higher odds of survival than penetrating trauma (OR, 5.97; 95% CI, 2.52-14.12; P = <0.001 = 1). Gender, tachycardia, tachypnea, and dispatch to arrival time did not impact a patient's likelihood of survival. CONCLUSIONS: Penetrating trauma has a higher mortality when compared with blunt trauma in Helicopter Emergency Services transported patients in a rural state. Perhaps a new algorithm in the management of penetrating trauma would include hemorrhage control at a locoregional hospital before definitive care. Further study is required to understand the exact variables that lead to a higher mortality in penetrating trauma in a rural state.


Assuntos
Resgate Aéreo , Ferimentos Penetrantes/terapia , Adolescente , Adulto , Feminino , Humanos , Escala de Gravidade do Ferimento , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , População Rural , Centros de Traumatologia , Ferimentos Penetrantes/mortalidade , Adulto Jovem
7.
Neuroimage ; 167: 224-236, 2018 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-27263508

RESUMO

Detecting regularities in the sensory environment licenses predictions that enable adaptive behaviour. However, it is unclear whether predictions about object category, location, or both dimensions are mediated by overlapping systems, and relatedly, whether constructing predictions about both category and location is associated with processing bottlenecks. To examine this issue, in an fMRI study, we presented participants with image-series in which non-deterministic transition probabilities enabled predictions about either the location of the next image, its semantic category, both dimensions, or neither (the latter forming a "no-regularity" random baseline condition). Speaking to a common system, all three predictable conditions resulted in reduced BOLD activity in four clusters: left rostral anterior cingulate cortex; bilateral putamen, caudate and thalamus; right precentral gyrus, and left visual cortex. Pointing to a processing bottleneck, in some regions, a significant interaction between the two factors was found whereby category-predictable series were associated with lower activity - but only when location regularity was absent. Finally, category regularity decreased activation in areas of the ventral visual stream and semantic areas of lateral temporal cortex, and location regularity decreased activation in a dorsal fronto-parietal cluster, long implicated in the endogenous control of spatial attention. Our findings confirm and expand a role for dACC/dmPFC and striatum in monitoring or responding to uncertainty in the environment and point to a limited capacity bottleneck when multiple predictions are concurrently licensed.


Assuntos
Antecipação Psicológica/fisiologia , Córtex Cerebral/fisiologia , Função Executiva/fisiologia , Neuroimagem Funcional/métodos , Neostriado/fisiologia , Desempenho Psicomotor/fisiologia , Incerteza , Adulto , Córtex Cerebral/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Neostriado/diagnóstico por imagem , Reconhecimento Visual de Modelos/fisiologia , Semântica , Percepção Espacial/fisiologia , Adulto Jovem
8.
Neuroimage ; 173: 509-517, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29477440

RESUMO

Current neurobiological models assign a central role to predictive processes calibrated to environmental statistics. Neuroimaging studies examining the encoding of stimulus uncertainty have relied almost exclusively on manipulations in which stimuli were presented in a single sensory modality, and further assumed that neural responses vary monotonically with uncertainty. This has left a gap in theoretical development with respect to two core issues: (i) are there cross-modal brain systems that encode input uncertainty in way that generalizes across sensory modalities, and (ii) are there brain systems that track input uncertainty in a non-monotonic fashion? We used multivariate pattern analysis to address these two issues using auditory, visual and audiovisual inputs. We found signatures of cross-modal encoding in frontoparietal, orbitofrontal, and association cortices using a searchlight cross-classification analysis where classifiers trained to discriminate levels of uncertainty in one modality were tested in another modality. Additionally, we found widespread systems encoding uncertainty non-monotonically using classifiers trained to discriminate intermediate levels of uncertainty from both the highest and lowest uncertainty levels. These findings comprise the first comprehensive report of cross-modal and non-monotonic neural sensitivity to statistical regularities in the environment, and suggest that conventional paradigms testing for monotonic responses to uncertainty in a single sensory modality may have limited generalizability.


Assuntos
Percepção Auditiva/fisiologia , Mapeamento Encefálico/métodos , Encéfalo/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica/métodos , Adulto , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Estimulação Luminosa/métodos , Adulto Jovem
9.
Neuroimage ; 157: 648-659, 2017 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-28527790

RESUMO

Understanding how humans code for and respond to environmental uncertainty/regularity is a question shared by current computational and neurobiological approaches to human cognition. To date, studies investigating neurobiological systems that track input uncertainty have examined responses to uni-sensory streams. It is not known, however, whether there exist brain systems that combine information about the regularity of input streams presented to different senses. We report an fMRI study that aimed to identify brain systems that relate statistical information across sensory modalities. We constructed temporally extended auditory and visual streams, each of which could be random or highly regular, and presented them concurrently. We found strong signatures of "regularity matching" in visual cortex bilaterally; responses were higher when the level of regularity in the auditory and visual streams mismatched than when it matched, [(AudHigh/VisLow and AudLow/VisHigh) >(AudLow/VisLow and AudHigh/VisHigh)]. In addition, several frontal and parietal regions tracked regularity of the auditory or visual stream independently of the other stream's regularity. An individual-differences analysis suggested that signatures of single-modality-focused regularity tracking in these fronto-parietal regions are inversely related to signatures of regularity-matching in visual cortex. Our findings suggest that i) visual cortex is a junction for integration of temporally-extended auditory and visual inputs and that ii) multisensory regularity-matching depends on balanced processing of both input modalities. We discuss the implications of these findings for neurobiological models of uncertainty and for understanding computations that underlie multisensory interactions in occipital cortex.


Assuntos
Percepção Auditiva/fisiologia , Mapeamento Encefálico/métodos , Cérebro/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto , Cérebro/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Fatores de Tempo , Córtex Visual/diagnóstico por imagem , Adulto Jovem
10.
Malar J ; 16(1): 353, 2017 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-28851358

RESUMO

BACKGROUND: Artemisinin-based combination therapy (ACT) is recommended as the first-line anti-malarial treatment strategy in sub-Saharan African countries. WHO policy recommends parasitological confirmation by microscopy or rapid diagnostic test (RDT) in all cases of suspected malaria prior to treatment. Gaps remain in understanding the factors that influence patient treatment-seeking behaviour and anti-malarial drug purchase decisions in the private sector. The objective of this study was to identify patient treatment-seeking behaviour in Ghana, Kenya, Nigeria, Tanzania, and Uganda. METHODS: Face-to-face patient interviews were conducted at a total of 208 randomly selected retail outlets in five countries. At each outlet, exit interviews were conducted with five patients who indicated they had come seeking anti-malarial treatment. The questionnaire was anonymous and standardized in the five countries and collected data on different factors, including socio-demographic characteristics, history of illness, diagnostic practices (i.e. microscopy or RDT), prescription practices and treatment purchase. The price paid for the treatment was also collected from the outlet vendor. RESULTS: A total of 994 patients were included from the five countries. Location of malaria diagnosis was significantly different in the five countries. A total of 484 blood diagnostic tests were performed, (72.3% with microscopy and 27.7% with RDT). ACTs were purchased by 72.5% of patients who had undergone blood testing and 86.5% of patients without a blood test, regardless of whether the test result was positive or negative (p < 10-4). A total of 531 patients (53.4%) had an anti-malarial drug prescription, of which 82.9% were prescriptions for an ACT. There were significant differences in prescriptions by country. A total of 923 patients (92.9%) purchased anti-malarial drugs in an outlet, including 79.1% of patients purchasing an ACT drug: 98.0% in Ghana, 90.5% in Kenya, 80.4% in Nigeria, 69.2% in Tanzania, and 57.7% in Uganda (p < 10-4). Having a drug prescription was not a significant predictive factor associated with an ACT drug purchase (except in Kenya). The number of ACT drugs purchased with a prescription was greater than the number purchased without a prescription in Kenya, Nigeria and Tanzania. CONCLUSIONS: This study highlights differences in drug prescription and purchase patterns in five sub-Saharan African countries. The private sector is playing an increasingly important role in fever case management in sub-Saharan Africa. Understanding the characteristics of private retail outlets and the role they play in providing anti-malaria drugs may support the design of effective malaria interventions.


Assuntos
Antimaláricos/economia , Antimaláricos/provisão & distribuição , Prescrições de Medicamentos/economia , Prescrições de Medicamentos/normas , Malária/tratamento farmacológico , Adolescente , Adulto , África Subsaariana , Antimaláricos/uso terapêutico , Artemisininas/uso terapêutico , Administração de Caso , Criança , Pré-Escolar , Comércio , Testes Diagnósticos de Rotina , Quimioterapia Combinada , Feminino , Gana , Setor de Assistência à Saúde/estatística & dados numéricos , Humanos , Quênia , Malária/diagnóstico , Masculino , Nigéria , Farmácias , Setor Privado , Inquéritos e Questionários , Tanzânia , Uganda , Adulto Jovem
11.
Neuroimage ; 130: 293-305, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26724779

RESUMO

Sleep has been shown to subtly disrupt the spatial organization of functional connectivity networks in the brain, but in a way that largely preserves the connectivity within sensory cortices. Here we evaluated the hypothesis that sleep does impact sensory cortices, but through alteration of activity dynamics. We therefore examined the impact of sleep on hemodynamics using a method for quantifying non-random, high frequency signatures of the blood-oxygen-level dependent (BOLD) signal (amplitude variance asymmetry; AVA). We found that sleep was associated with the elimination of these dynamics in a manner that is restricted to auditory, motor and visual cortices. This elimination was concurrent with increased variance of activity in these regions. Functional connectivity between regions showing AVA during wakefulness maintained a relatively consistent hierarchical structure during wakefulness and N1 and N2 sleep, despite a gradual reduction of connectivity strength as sleep progressed. Thus, sleep is related to elimination of high frequency non-random activity signatures in sensory cortices that are robust during wakefulness. The elimination of these AVA signatures conjointly with preservation of the structure of functional connectivity patterns may be linked to the need to suppress sensory inputs during sleep while still maintaining the capacity to react quickly to complex multimodal inputs.


Assuntos
Mapeamento Encefálico/métodos , Vias Neurais/fisiologia , Sono/fisiologia , Córtex Somatossensorial/fisiologia , Eletroencefalografia , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Córtex Motor/fisiologia , Processamento de Sinais Assistido por Computador , Vigília/fisiologia , Adulto Jovem
12.
Neuroimage ; 131: 181-92, 2016 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-26188261

RESUMO

We studied a group of verbal memory specialists to determine whether intensive oral text memory is associated with structural features of hippocampal and lateral-temporal regions implicated in language processing. Professional Vedic Sanskrit Pandits in India train from childhood for around 10years in an ancient, formalized tradition of oral Sanskrit text memorization and recitation, mastering the exact pronunciation and invariant content of multiple 40,000-100,000 word oral texts. We conducted structural analysis of gray matter density, cortical thickness, local gyrification, and white matter structure, relative to matched controls. We found massive gray matter density and cortical thickness increases in Pandit brains in language, memory and visual systems, including i) bilateral lateral temporal cortices and ii) the anterior cingulate cortex and the hippocampus, regions associated with long and short-term memory. Differences in hippocampal morphometry matched those previously documented for expert spatial navigators and individuals with good verbal working memory. The findings provide unique insight into the brain organization implementing formalized oral knowledge systems.


Assuntos
Hipocampo/anatomia & histologia , Idioma , Memória/fisiologia , Lobo Temporal/anatomia & histologia , Aprendizagem Verbal/fisiologia , Córtex Visual/anatomia & histologia , Córtex Visual/fisiologia , Adolescente , Criança , Hipocampo/fisiologia , Humanos , Índia , Masculino , Lobo Temporal/fisiologia , Adulto Jovem
13.
Neuroimage ; 108: 292-300, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25536493

RESUMO

Complex systems are described according to two central dimensions: (a) the randomness of their output, quantified via entropy; and (b) their complexity, which reflects the organization of a system's generators. Whereas some approaches hold that complexity can be reduced to uncertainty or entropy, an axiom of complexity science is that signals with very high or very low entropy are generated by relatively non-complex systems, while complex systems typically generate outputs with entropy peaking between these two extremes. In understanding their environment, individuals would benefit from coding for both input entropy and complexity; entropy indexes uncertainty and can inform probabilistic coding strategies, whereas complexity reflects a concise and abstract representation of the underlying environmental configuration, which can serve independent purposes, e.g., as a template for generalization and rapid comparisons between environments. Using functional neuroimaging, we demonstrate that, in response to passively processed auditory inputs, functional integration patterns in the human brain track both the entropy and complexity of the auditory signal. Connectivity between several brain regions scaled monotonically with input entropy, suggesting sensitivity to uncertainty, whereas connectivity between other regions tracked entropy in a convex manner consistent with sensitivity to input complexity. These findings suggest that the human brain simultaneously tracks the uncertainty of sensory data and effectively models their environmental generators.


Assuntos
Percepção Auditiva/fisiologia , Mapeamento Encefálico/métodos , Encéfalo/fisiologia , Entropia , Vias Neurais/fisiologia , Adulto , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética , Masculino , Modelos Neurológicos
14.
Hum Brain Mapp ; 36(2): 519-37, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25293364

RESUMO

Neuroimaging studies have shown that task demands affect connectivity patterns in the human brain not only during task performance but also during subsequent rest periods. Our goal was to determine whether ongoing connectivity patterns during rest contain information about both the current rest state, as well as the recently terminated task. Our experimental design consisted of two types of active tasks that were followed by two types of low-demand rest states. Using this design, we examined whether hippocampal functional connectivity during wakeful rest reflects both features of a recently terminated task and those of the current resting-state condition. We identified four types of networks: (i) one whose connectivity with the hippocampus was determined only by features of a recently terminated task, (ii) one whose connectivity was determined only by features of the current resting-state, (iii) one whose connectivity reflected aspects of both the recently terminated task and ongoing resting-state features, and (iv) one whose connectivity with the hippocampus was strong, but not affected by any external factor. The left and right hippocampi played distinct roles in these networks. These findings suggest that ongoing hippocampal connectivity networks mediate information integration across multiple temporal scales, with hippocampal laterality moderating these connectivity patterns.


Assuntos
Lateralidade Funcional/fisiologia , Hipocampo/fisiologia , Adulto , Atenção/fisiologia , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Vias Neurais/fisiologia , Testes Neuropsicológicos , Descanso , Vigília
15.
Cereb Cortex ; 24(5): 1332-50, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-23329729

RESUMO

It is known that the brain's resting-state activity (RSA) is organized in low frequency oscillations that drive network connectivity. Recent research has also shown that elements of RSA described by high-frequency and nonoscillatory properties are non-random and functionally relevant. Motivated by this research, we investigated nonoscillatory aspects of the blood-oxygen-level-dependent (BOLD) RSA using a novel method for characterizing subtle fluctuation dynamics. The metric that we develop quantifies the relative variance of the amplitude of local-maxima and local-minima in a BOLD time course (amplitude variance asymmetry; AVA). This metric reveals new properties of RSA activity, without relying on connectivity as a descriptive tool. We applied the AVA analysis to data from 3 different participant groups (2 adults, 1 child) collected from 3 different centers. The analyses show that AVA patterns a) identify 3 types of RSA profiles in adults' sensory systems b) differ in topology and pattern of dynamics in adults and children, and c) are stable across magnetic resonance scanners. Furthermore, children with higher IQ demonstrated more adult-like AVA patterns. These findings indicate that AVA reflects important and novel dimensions of brain development and RSA.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Mapeamento Encefálico , Encéfalo/irrigação sanguínea , Circulação Cerebrovascular/fisiologia , Descanso/fisiologia , Adulto , Análise de Variância , Transtorno do Deficit de Atenção com Hiperatividade/patologia , Encéfalo/crescimento & desenvolvimento , Encéfalo/patologia , Criança , Estudos de Coortes , Conjuntos de Dados como Assunto , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Oxigênio/sangue , Adulto Jovem
16.
J Med Chem ; 67(2): 1115-1126, 2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38215028

RESUMO

The development of more effective drugs requires knowledge of their bioavailability and binding efficacy directly in the native cellular environment. In-cell nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for investigating ligand-target interactions directly in living cells. However, the target molecule may be NMR-invisible due to interactions with cellular components, while observing the ligand by 1H NMR is impractical due to the cellular background. Such limitations can be overcome by observing fluorinated ligands by 19F in-cell NMR as they bind to the intracellular target. Here we report a novel approach based on real-time in-cell 19F NMR that allows measuring ligand binding affinities in human cells by competition binding, using a fluorinated compound as a reference. The binding of a set of compounds toward Hsp90α was investigated. In principle, this approach could be applied to other pharmacologically relevant targets, thus aiding the design of more effective compounds in the early stages of drug development.


Assuntos
Imageamento por Ressonância Magnética , Humanos , Ligação Competitiva , Ligantes , Espectroscopia de Ressonância Magnética/métodos , Ligação Proteica , Flúor/química
17.
SLAS Discov ; 29(1): 40-51, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37714432

RESUMO

Surface plasmon resonance (SPR) biosensor methods are ideally suited for fragment-based lead discovery.  However, generally applicable experimental procedures and detailed protocols are lacking, especially for structurally or physico-chemically challenging targets or when tool compounds are not available. Success depends on accounting for the features of both the target and the chemical library, purposely designing screening experiments for identification and validation of hits with desired specificity and mode-of-action, and availability of orthogonal methods capable of confirming fragment hits. The range of targets and libraries amenable to an SPR biosensor-based approach for identifying hits is considerably expanded by adopting multiplexed strategies, using multiple complementary surfaces or experimental conditions. Here we illustrate principles and multiplexed approaches for using flow-based SPR biosensor systems for screening fragment libraries of different sizes (90 and 1056 compounds) against a selection of challenging targets. It shows strategies for the identification of fragments interacting with 1) large and structurally dynamic targets, represented by acetyl choline binding protein (AChBP), a Cys-loop receptor ligand gated ion channel homologue, 2) targets in multi protein complexes, represented by lysine demethylase 1 and a corepressor (LSD1/CoREST), 3) structurally variable or unstable targets, represented by farnesyl pyrophosphate synthase (FPPS), 4) targets containing intrinsically disordered regions, represented by protein tyrosine phosphatase 1B  (PTP1B), and 5) aggregation-prone proteins, represented by an engineered form of human tau  (tau K18M). Practical considerations and procedures accounting for the characteristics of the proteins and libraries, and that increase robustness, sensitivity, throughput and versatility are highlighted. The study shows that the challenges for addressing these types of targets is not identification of potentially useful fragments per se, but establishing methods for their validation and evolution into leads.


Assuntos
Técnicas Biossensoriais , Ressonância de Plasmônio de Superfície , Humanos , Ressonância de Plasmônio de Superfície/métodos , Bibliotecas de Moléculas Pequenas/farmacologia , Proteínas , Proteínas de Transporte
18.
ACS Chem Neurosci ; 15(3): 671-684, 2024 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-38238043

RESUMO

α1A-, α1B-, and α1D-adrenoceptors (α1-ARs) are members of the adrenoceptor G protein-coupled receptor family that are activated by adrenaline (epinephrine) and noradrenaline. α1-ARs are clinically targeted using antagonists that have minimal subtype selectivity, such as prazosin and tamsulosin, to treat hypertension and benign prostatic hyperplasia, respectively. Abundant expression of α1-ARs in the heart and central nervous system (CNS) makes these receptors potential targets for the treatment of cardiovascular and CNS disorders, such as heart failure, epilepsy, and Alzheimer's disease. Our understanding of the precise physiological roles of α1-ARs, however, and their involvement in disease has been hindered by the lack of sufficiently subtype-selective tool compounds, especially for α1B-AR. Here, we report the discovery of 4-[(2-hydroxyethyl)amino]-6-methyl-2H-chromen-2-one (Cpd1), as an α1B-AR antagonist that has 10-15-fold selectivity over α1A-AR and α1D-AR. Through computational and site-directed mutagenesis studies, we have identified the binding site of Cpd1 in α1B-AR and propose the molecular basis of α1B-AR selectivity, where the nonconserved V19745.52 residue plays a major role, with contributions from L3146.55 within the α1B-AR pocket. By exploring the structure-activity relationships of Cpd1 at α1B-AR, we have also identified 3-[(cyclohexylamino)methyl]-6-methylquinolin-2(1H)-one (Cpd24), which has a stronger binding affinity than Cpd1, albeit with reduced selectivity for α1B-AR. Cpd1 and Cpd24 represent potential leads for α1B-AR-selective drug discovery and novel tool molecules to further study the physiology of α1-ARs.


Assuntos
Prazosina , Receptores Adrenérgicos alfa 1 , Receptores Adrenérgicos alfa 1/metabolismo , Tansulosina , Norepinefrina
19.
Anal Chem ; 85(14): 6756-66, 2013 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-23806099

RESUMO

The increasing use of fragment-based lead discovery (FBLD) in industry as well as in academia creates a high demand for sensitive and reliable methods to detect the binding of fragments to act as starting points in drug discovery programs. Nuclear magnetic resonance (NMR), surface plasmon resonance (SPR), and X-ray crystallography are well-established methods for fragment finding, and thermal shift and fluorescence polarization (FP) assays are used to a lesser extent. Weak affinity chromatography (WAC) was recently introduced as a new technology for fragment screening. The study presented here compares screening of 111 fragments against the ATPase domain of HSP90 by all of these methods, with isothermal titration calorimetry (ITC) used to confirm the most potent hits. The study demonstrates that WAC is comparable to the established methods of ligand-based NMR and SPR as a hit-id method, with hit correlations of 88% and 83%, respectively. The stability of HSP90 WAC columns was also evaluated and found to give 90% reproducibility even after 207 days of storage. A good correlation was obtained between the various technologies, validating WAC as an effective technology for fragment screening.


Assuntos
Cromatografia de Afinidade/métodos , Proteínas de Choque Térmico HSP90/análise , Fragmentos de Peptídeos/análise , Sequência de Aminoácidos , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos/métodos , Proteínas de Choque Térmico HSP90/genética , Dados de Sequência Molecular , Fragmentos de Peptídeos/genética , Estrutura Terciária de Proteína
20.
Malar J ; 12: 135, 2013 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-23607504

RESUMO

BACKGROUND: In 2009, the Global Fund to Fight AIDS, Tuberculosis and Malaria established the Affordable Medicines Facility-malaria (AMFm) in order to increase access to quality-assured artemisinin combination therapy (QAACT). AMFm Phase 1, which includes nine pilot programmes in eight countries, was launched in 2009. The objective of this study was to assess anti-malarial stock and purchase patterns at private outlets in five AMFm Phase 1 countries in regard to three of the core AMFm goals: increase the affordability of QAACT, increase the availability of QAACT, and crowd out artemisinin monotherapies and other substandard therapies. METHODS: The study was conducted between April and May 2012 and included interviews with personnel in 598 private pharmaceutical outlets in Ghana, Kenya, Nigeria, Tanzania, and Uganda. Questionnaires were administered at private retail outlets and the data were analyzed to assess within- and between-country differences in QAACT price, availability, and popularity. RESULTS: AMFm medications were less expensive than their non-AMFm counterparts, yet prices for both types were above country-specific suggested retail prices. Market penetration of AMFm QAACT in both urban and rural areas was high, although stock-outs of both AMFm and non-AMFm products were more common in rural compared with urban outlets in Ghana and Kenya (p = 0.0013). Government recommendation was the most significant factor influencing anti-malarial stock choices in urban (41.5%) and rural (31.9%) outlets. The three top-selling anti-malarials reported for both urban and rural areas in each country were, with the exception of rural Uganda and urban Nigeria, combination therapies. CONCLUSIONS: Results from this study indicate that the AMFm has not fully achieved its affordability and crowd-out objectives. Still, the final purchase price of AMFm QAACT was substantially lower than non-AMFm equivalents. Moreover, for both urban and rural areas, AMFm QAACT availability was found to be high, and the various forms of QAACT were the best-selling products among all anti-malarials. These findings suggest a continued need for initiatives like the AMFm that improve the affordability and accessibility of QAACT. Similar programmes may be especially effective if employed in combination with rapid diagnostic testing to ensure the appropriate use of these products.


Assuntos
Artemisininas/uso terapêutico , Acessibilidade aos Serviços de Saúde , Malária/tratamento farmacológico , Setor Privado , África , Quimioterapia Combinada/métodos , Humanos , Entrevistas como Assunto , Farmácias , Avaliação de Programas e Projetos de Saúde , Inquéritos e Questionários
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