Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 499
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Nature ; 585(7826): 545-550, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32968258

RESUMO

To constrain global warming, we must strongly curtail greenhouse gas emissions and capture excess atmospheric carbon dioxide1,2. Regrowing natural forests is a prominent strategy for capturing additional carbon3, but accurate assessments of its potential are limited by uncertainty and variability in carbon accumulation rates2,3. To assess why and where rates differ, here we compile 13,112 georeferenced measurements of carbon accumulation. Climatic factors explain variation in rates better than land-use history, so we combine the field measurements with 66 environmental covariate layers to create a global, one-kilometre-resolution map of potential aboveground carbon accumulation rates for the first 30 years of natural forest regrowth. This map shows over 100-fold variation in rates across the globe, and indicates that default rates from the Intergovernmental Panel on Climate Change (IPCC)4,5 may underestimate aboveground carbon accumulation rates by 32 per cent on average and do not capture eight-fold variation within ecozones. Conversely, we conclude that maximum climate mitigation potential from natural forest regrowth is 11 per cent lower than previously reported3 owing to the use of overly high rates for the location of potential new forest. Although our data compilation includes more studies and sites than previous efforts, our results depend on data availability, which is concentrated in ten countries, and data quality, which varies across studies. However, the plots cover most of the environmental conditions across the areas for which we predicted carbon accumulation rates (except for northern Africa and northeast Asia). We therefore provide a robust and globally consistent tool for assessing natural forest regrowth as a climate mitigation strategy.


Assuntos
Sequestro de Carbono , Carbono/metabolismo , Agricultura Florestal/estatística & dados numéricos , Agricultura Florestal/tendências , Florestas , Mapeamento Geográfico , Árvores/crescimento & desenvolvimento , Árvores/metabolismo , Conservação dos Recursos Naturais , Coleta de Dados , Recuperação e Remediação Ambiental , Aquecimento Global/prevenção & controle , Internacionalidade , Cinética
2.
Ecol Lett ; 27(5): e14427, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38698677

RESUMO

Tree diversity can promote both predator abundance and diversity. However, whether this translates into increased predation and top-down control of herbivores across predator taxonomic groups and contrasting environmental conditions remains unresolved. We used a global network of tree diversity experiments (TreeDivNet) spread across three continents and three biomes to test the effects of tree species richness on predation across varying climatic conditions of temperature and precipitation. We recorded bird and arthropod predation attempts on plasticine caterpillars in monocultures and tree species mixtures. Both tree species richness and temperature increased predation by birds but not by arthropods. Furthermore, the effects of tree species richness on predation were consistent across the studied climatic gradient. Our findings provide evidence that tree diversity strengthens top-down control of insect herbivores by birds, underscoring the need to implement conservation strategies that safeguard tree diversity to sustain ecosystem services provided by natural enemies in forests.


Assuntos
Artrópodes , Biodiversidade , Aves , Clima , Comportamento Predatório , Árvores , Animais , Artrópodes/fisiologia , Aves/fisiologia , Cadeia Alimentar , Larva/fisiologia
3.
Neurobiol Dis ; 196: 106512, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38670278

RESUMO

Neurons in the substantia nigra reticulata (SNr) transmit information about basal ganglia output to dozens of brain regions in thalamocortical and brainstem motor networks. Activity of SNr neurons is regulated by convergent input from upstream basal ganglia nuclei, including GABAergic inputs from the striatum and the external globus pallidus (GPe). GABAergic inputs from the striatum convey information from the direct pathway, while GABAergic inputs from the GPe convey information from the indirect pathway. Chronic loss of dopamine, as occurs in Parkinson's disease, disrupts the balance of direct and indirect pathway neurons at the level of the striatum, but the question of how dopamine loss affects information propagation along these pathways outside of the striatum is less well understood. Using a combination of in vivo and slice electrophysiology, we find that dopamine depletion selectively weakens the direct pathway's influence over neural activity in the SNr due to changes in the decay kinetics of GABA-mediated synaptic currents. GABAergic signaling from GPe neurons in the indirect pathway was not affected, resulting in an inversion of the normal balance of inhibitory control over basal ganglia output through the SNr. These results highlight the contribution of cellular mechanisms outside of the striatum that impact the responses of basal ganglia output neurons to the direct and indirect pathways in disease.


Assuntos
Dopamina , Neurônios , Parte Reticular da Substância Negra , Animais , Dopamina/metabolismo , Neurônios/metabolismo , Neurônios/fisiologia , Parte Reticular da Substância Negra/fisiologia , Parte Reticular da Substância Negra/metabolismo , Vias Neurais/fisiologia , Vias Neurais/metabolismo , Camundongos , Masculino , Camundongos Endogâmicos C57BL , Oxidopamina/farmacologia , Ácido gama-Aminobutírico/metabolismo , Neurônios GABAérgicos/fisiologia , Neurônios GABAérgicos/metabolismo
4.
Radiology ; 311(2): e231386, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38713023

RESUMO

Background Limited data are available on radiation segmentectomy (RS) for treatment of hepatocellular carcinoma (HCC) using yttrium 90 (90Y) resin microsphere doses determined by using a single-compartment medical internal radiation dosimetry (MIRD) model. Purpose To evaluate the efficacy and safety of RS treatment of HCC with 90Y resin microspheres using a single-compartment MIRD model and correlate posttreatment dose with outcomes. Materials and Methods This retrospective single-center study included adult patients with HCC who underwent RS with 90Y resin microspheres between July 2014 and December 2022. Posttreatment PET/CT and dosimetry were performed. Adverse events were assessed using the Common Terminology Criteria for Adverse Events, version 5.0. Per-lesion and overall response rates (ie, complete response [CR], objective response, disease control, and duration of response) were assessed at imaging using the Modified Response Evaluation Criteria in Solid Tumors, and overall survival (OS) was assessed using Kaplan-Meier analysis. Results Among 67 patients (median age, 69 years [IQR, 63-78 years]; 54 male patients) with HCC, median tumor absorbed dose was 232 Gy (IQR, 163-405 Gy). At 3 months, per-lesion and overall (per-patient) CR was achieved in 47 (70%) and 41 (61%) of 67 patients, respectively. At 6 months (n = 46), per-lesion rates of objective response and disease control were both 94%, and per-patient rates were both 78%. A total of 88% (95% CI: 79 99) and 72% (95% CI: 58, 90) of patients had a per-lesion and overall duration of response of 1 year or greater. At 1 month, a grade 3 clinical adverse event (abdominal pain) occurred in one of 67 (1.5%) patients. Median posttreatment OS was 26 months (95% CI: 20, not reached). Disease progression at 2 years was lower in the group that received 300 Gy or more than in the group that received less than 300 Gy (17% vs 61%; P = .047), with no local progression in the former group through the end of follow-up. Conclusion Among patients with HCC who underwent RS with 90Y resin microspheres, 88% and 72% achieved a per-lesion and overall duration of response of 1 year or greater, respectively, with one grade 3 adverse event. In patients whose tumors received 300 Gy or more according to posttreatment dosimetry, a disease progression benefit was noted. © RSNA, 2024 Supplemental material is available for this article.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Microesferas , Radioisótopos de Ítrio , Humanos , Masculino , Carcinoma Hepatocelular/radioterapia , Carcinoma Hepatocelular/diagnóstico por imagem , Feminino , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/diagnóstico por imagem , Pessoa de Meia-Idade , Radioisótopos de Ítrio/uso terapêutico , Idoso , Estudos Retrospectivos , Resultado do Tratamento , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos
5.
New Phytol ; 243(3): 1205-1219, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38855965

RESUMO

Decades of studies have demonstrated links between biodiversity and ecosystem functioning, yet the generality of the relationships and the underlying mechanisms remain unclear, especially for forest ecosystems. Using 11 tree-diversity experiments, we tested tree species richness-community productivity relationships and the role of arbuscular (AM) or ectomycorrhizal (ECM) fungal-associated tree species in these relationships. Tree species richness had a positive effect on community productivity across experiments, modified by the diversity of tree mycorrhizal associations. In communities with both AM and ECM trees, species richness showed positive effects on community productivity, which could have resulted from complementarity between AM and ECM trees. Moreover, both AM and ECM trees were more productive in mixed communities with both AM and ECM trees than in communities assembled by their own mycorrhizal type of trees. In communities containing only ECM trees, species richness had a significant positive effect on productivity, whereas species richness did not show any significant effects on productivity in communities containing only AM trees. Our study provides novel explanations for variations in diversity-productivity relationships by suggesting that tree-mycorrhiza interactions can shape productivity in mixed-species forest ecosystems.


Assuntos
Biodiversidade , Micorrizas , Árvores , Micorrizas/fisiologia , Árvores/microbiologia , Especificidade da Espécie
6.
Ann Fam Med ; 22(2): 81-88, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38383045

RESUMO

BACKGROUND: Electronic health records (EHR) have become commonplace in medicine. A disconnect between developers and users while creating the interface often fails to create a product that captures clinical workflow, and issues become apparent with implementation. Optimization allows collaboration of clinicians and informaticists after implementation, but documentation of success has only been at the institutional level. METHODS: A 4-month, department-wide EHR optimization was conducted with information technology (IT). Optimizations were developed from an intensive quality improvement process involving all levels of clinicians and clinical staff. The optimizations were then categorized as accommodations (department adjusted workflow to EHR), creations (IT developed new workflows within EHR), discoveries (department found workflows within EHR), and modifications (IT changed workflows within EHR). Departmental productivity, defined as number of visits, charges, and payments, was standardized to ratios prior to the COVID-19 pandemic and evaluated by Taylor's change point analysis. Significant improvements were defined as shifts (change points), trends (5 or more consecutive values above/below the mean), and values outside 95% CIs. RESULTS: The 124 optimizations were categorized as 43 accommodations, 13 creations, 54 discoveries, and 14 modifications. Productivity ratios of monthly charges (0.74 to 1.28) and payments (0.83 to 1.58) significantly improved with the optimization efforts. Monthly visit ratios increased (0.65 to 0.98) but did not change significantly. CONCLUSION: Departmental collaboration with organizational IT for EHR optimization focused on detailed analysis of how workflows can impact productivity. Discovery optimization predominance indicates many solutions to EHR usability problems were already in the system. A large proportion of accommodation optimizations reinforced the need for better developer-user collaboration before implementation.Annals Early Access.


Assuntos
Registros Eletrônicos de Saúde , Medicina , Humanos , Melhoria de Qualidade , Pandemias
7.
Environ Sci Technol ; 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38329046

RESUMO

Labile carbon (C) continuously delivered from the rhizosphere profoundly affects terrestrial nitrogen (N) cycling. However, nitrous oxide (N2O) and dinitrogen (N2) production in agricultural soils in the presence of continuous root C exudation with applied N remains poorly understood. We conducted an incubation experiment using artificial roots to continuously deliver small-dose labile C combined with 15N tracers to investigate N2O and N2 emissions in agricultural soils with pH and organic C (SOC) gradients. A significantly negative exponential relationship existed between N2O and N2 emissions under continuous C exudation. Increasing soil pH significantly promoted N2 emissions while reducing N2O emissions. Higher SOC further promoted N2 emissions in alkaline soils. Native soil-N (versus fertilizer-N) was the main source of N2O (average 67%) and N2 (average 80%) emissions across all tested soils. Our study revealed the overlooked high N2 emissions, mainly derived from native soil-N and strengthened by increasing soil pH, under relatively real-world conditions with continuous root C exudation. This highlights the important role of N2O and N2 production from native soil-N in terrestrial N cycling when there is a continuous C supply (e.g., plant-root exudate) and helps mitigate emissions and constrain global budgets of the two concerned nitrogenous gases.

8.
Scand J Med Sci Sports ; 34(3): e14598, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38458996

RESUMO

This study presents the sleep characteristics of British student-athletes and examines the relationships between sport scheduling and time demands on sleep outcomes. Student-athletes (n = 157, 51% male) completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and the Sleep Hygiene Index (SHI). Self-reported sleep characteristics on weekdays and weekends, weekly frequencies of early morning and late evening sport sessions, and academic-related and sport-related time demands were also collected. Questionnaires revealed a high prevalence of undesired sleep characteristics including poor sleep quality (global PSQI >5 in 49.0%) and low sleep durations on weekdays (25% reporting <7 h). Paired t-tests revealed significant differences in bedtime, waketime, sleep duration, and sleep onset latency between weekdays and weekends (all p < 0.01). Hierarchical regression analyses indicated that early morning sport frequency was a significant predictor of PSQI (ß = 0.30) and SHI (ß = 0.24) global scores, weekday waketimes (ß = -0.17), and weekday sleep durations (ß = -0.25; all p < 0.05) in models adjusted for participant characteristics. Late evening sport frequency, and academic-related and sport-related time demands, were not significant predictors of any sleep outcome. Adjusting sport scheduling to avoid early start times could provide a means to improve sleep outcomes and may improve sporting performance and academic attainment.


Assuntos
Distúrbios do Início e da Manutenção do Sono , Esportes , Humanos , Masculino , Feminino , Sono , Atletas , Inquéritos e Questionários , Estudantes
9.
Behav Sleep Med ; : 1-23, 2024 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-38965766

RESUMO

BACKGROUND: Athletes display a high prevalence of undesired sleep characteristics that may affect both performance and wellbeing. OBJECTIVES: This scoping review aimed to identify and map the existing evidence of behavioral sleep interventions and their effects on sleep outcomes in athletes, and retrospectively code the behavior change techniques (BCTs) implemented using the Behavior Change Technique Taxonomy (BCTTv1). METHODS: Conducted following the JBI methodology for scoping reviews, four online databases were used to identify prospective interventions with at least one behavioral component in competitive athletes, and reporting a sleep outcome pre- and post-intervention. RESULTS: Thirty-three studies met the inclusion criteria, encompassing 892 participants with a median age of 23. Five intervention categories were identified (education, mind-body practices, direct, multi-component, and other), with each demonstrating mixed efficacy but the potential to improve sleep outcomes. The BCTs varied in type and frequency between each category, with only 18 unique BCTs identified across all studies. CONCLUSIONS: The varied efficacy of previous studies at improving sleep outcomes may be attributed to the lack of behavior change theory applied during intervention development. Designing interventions following a targeted specification of the behavioral problem, and the integration of corresponding BCTs should be considered in future research.

10.
J Virol ; 96(18): e0130522, 2022 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-36094313

RESUMO

Curriculum guidelines for virology are needed to best guide student learning due to the continuous and ever-increasing volume of virology information, the need to ensure that undergraduate and graduate students have a foundational understanding of key virology concepts, and the importance in being able to communicate that understanding to both other virologists and nonvirologists. Such guidelines, developed by virology educators and the American Society for Virology Education and Career Development Committee, are described herein.


Assuntos
Currículo , Universidades , Virologia , Educação de Pós-Graduação , Estados Unidos , Virologia/educação
11.
PLoS Pathog ; 17(7): e1009494, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34237110

RESUMO

The mammalian orthoreovirus double-stranded (ds) RNA-binding protein σ3 is a multifunctional protein that promotes viral protein synthesis and facilitates viral entry and assembly. The dsRNA-binding capacity of σ3 correlates with its capacity to prevent dsRNA-mediated activation of protein kinase R (PKR). However, the effect of σ3 binding to dsRNA during viral infection is largely unknown. To identify functions of σ3 dsRNA-binding activity during reovirus infection, we engineered a panel of thirteen σ3 mutants and screened them for the capacity to bind dsRNA. Six mutants were defective in dsRNA binding, and mutations in these constructs cluster in a putative dsRNA-binding region on the surface of σ3. Two recombinant viruses expressing these σ3 dsRNA-binding mutants, K287T and R296T, display strikingly different phenotypes. In a cell-type dependent manner, K287T, but not R296T, replicates less efficiently than wild-type (WT) virus. In cells in which K287T virus demonstrates a replication deficit, PKR activation occurs and abundant stress granules (SGs) are formed at late times post-infection. In contrast, the R296T virus retains the capacity to suppress activation of PKR and does not mediate formation of SGs at late times post-infection. These findings indicate that σ3 inhibits PKR independently of its capacity to bind dsRNA. In infected mice, K287T produces lower viral titers in the spleen, liver, lungs, and heart relative to WT or R296T. Moreover, mice inoculated with WT or R296T viruses develop myocarditis, whereas those inoculated with K287T do not. Overall, our results indicate that σ3 functions to suppress PKR activation and subsequent SG formation during viral infection and that these functions correlate with virulence in mice.


Assuntos
Miocardite/virologia , Proteínas de Ligação a RNA/metabolismo , Infecções por Reoviridae/metabolismo , Proteínas Virais/metabolismo , Fatores de Virulência/metabolismo , Células A549 , Animais , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Miocardite/metabolismo , eIF-2 Quinase/metabolismo
12.
Br J Clin Pharmacol ; 89(9): 2767-2774, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37101414

RESUMO

AIMS: To mediate its pharmacodynamic effects, glyceryl trinitrate (GTN) requires bioactivation, by which it releases nitric oxide or a nitric oxide moiety. The exact mechanism of GTN bioactivation remains uncertain. Mitochondrial aldehyde dehydrogenase (ALDH-2) has been proposed as the primary enzyme responsible for this bioactivation process. Evidence for the importance of ALDH-2 in GTN bioactivation has been inconsistent, particularly in human models. An alternative hypothesis suggests that decreased ALDH-2 activity leads to accumulation of reactive cytotoxic aldehydes, which either inhibit the vasoactive product(s) of GTN or impair other enzymatic pathways involved in the bioactivation of GTN. We investigated the effect of supplemental vitamin C on vascular responses to GTN in healthy volunteers of East Asian descent, of whom 12 with and 12 without the ALDH-2 polymorphism participated. METHODS: Subjects underwent 2 sequential brachial artery infusions of GTN at rates of 5, 11 and 22 nmol/min, separated by a 30-min washout period. The GTN infusions were carried out in the presence and absence of vitamin C using a randomized, crossover design. Venous occlusion plethysmography was used to measure forearm blood flow responses to GTN. RESULTS: Compared to subjects with functional ALDH-2, the variant group exhibited blunted hemodynamic responses to intra-arterial GTN infusions, although this reduction in response was not statically significant. Contrary to our hypothesis, vitamin C had an inhibitory effect on GTN mediated vasodilation as compared to GTN during saline in both groups. CONCLUSION: We conclude that vitamin C did not augment the acute vascular response to GTN in those with the ALDH-2 polymorphism.


Assuntos
Aldeído-Desidrogenase Mitocondrial , Ácido Ascórbico , Nitroglicerina , Vasodilatação , Humanos , Ácido Ascórbico/farmacologia , Óxido Nítrico/metabolismo , Nitroglicerina/farmacologia , Vasodilatadores/farmacologia , Vitaminas , Aldeído-Desidrogenase Mitocondrial/genética
13.
Nat Methods ; 16(1): 59-62, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30559431

RESUMO

We describe droplet-assisted RNA targeting by single-cell sequencing (DART-seq), a versatile technology that enables multiplexed amplicon sequencing and transcriptome profiling in single cells. We applied DART-seq to simultaneously characterize the non-A-tailed transcripts of a segmented dsRNA virus and the transcriptome of the infected cell. In addition, we used DART-seq to simultaneously determine the natively paired, variable region heavy and light chain amplicons and the transcriptome of B lymphocytes.


Assuntos
Perfilação da Expressão Gênica , Análise de Célula Única/métodos , Transcriptoma , Animais , Linfócitos B/metabolismo , Linhagem Celular , Camundongos , Reação em Cadeia da Polimerase em Tempo Real , Transcrição Reversa
14.
J Card Fail ; 28(3): 385-393, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34487814

RESUMO

OBJECTIVE: Understanding cardiorenal pathophysiology in heart failure (HF) is of clinical importance. We sought to characterize the renal hemodynamic function and the transrenal gradient of the renin-angiotensin-aldosterone system (RAAS) markers in patients with HF and in controls without HF. METHODS: In this post hoc analysis, the glomerular filtration rate (GFRinulin), effective renal plasma flow (ERPFPAH) and transrenal gradients (arterial-renal vein) of angiotensin converting enzyme (ACE), aldosterone, and plasma renin activity (PRA) were measured in 47 patients with HF and in 24 controls. Gomez equations were used to derive afferent (RA) and efferent (RE) arteriolar resistances. Transrenal RAAS gradients were also collected in patients treated with intravenous dobutamine (HF, n = 11; non-HF, n = 11) or nitroprusside (HF, n = 18; non-HF, n = 5). RESULTS: The concentrations of PRA, aldosterone and ACE were higher in the renal vein vs the artery in patients with HF vs patients without HF (P < 0.01). In patients with HF, a greater ACE gradient was associated with greater renal vascular resistance (r = 0.42; P 0.007) and greater arteriolar resistances (RA: r = 0.39; P = 0.012; RE: r = 0.48; P = 0.002). Similarly, a greater aldosterone gradient was associated with lower GFR (r = -0.51; P = 0.0007) and renal blood flow (RBF), r = -0.32; P = 0.042) whereas greater PRA gradient with lower ERPF (r = -0.33; P = 0.040), GFR (r = -0.36; P = 0.024), and RBF (r = -0.33; P = 0.036). Dobutamine and nitroprusside treatment decreased the transrenal gradient of ACE (P = 0.012, P < 0.0001, respectively), aldosterone (P = 0.005, P = 0.030) and PRA (P = 0.014, P = 0.002) in patients with HF only. CONCLUSIONS: A larger transrenal RAAS marker gradient in patients with HF suggests a renal origin for neurohormonal activation associated with a vasoconstrictive renal profile.


Assuntos
Insuficiência Cardíaca , Sistema Renina-Angiotensina , Aldosterona/uso terapêutico , Biomarcadores , Dobutamina/uso terapêutico , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/tratamento farmacológico , Hemodinâmica , Humanos , Nitroprussiato/uso terapêutico , Renina/uso terapêutico
15.
J Comput Neurosci ; 51(3): 361-380, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-37266768

RESUMO

Parkinson's disease (PD) and animal models of PD feature enhanced oscillations in several frequency bands in the basal ganglia (BG). Past research has emphasized the enhancement of 13-30 Hz beta oscillations. Recently, however, oscillations in the delta band (0.5-4 Hz) have been identified as a robust predictor of dopamine loss and motor dysfunction in several BG regions in mouse models of PD. In particular, delta oscillations in the substantia nigra pars reticulata (SNr) were shown to lead oscillations in motor cortex (M1) and persist under M1 lesion, but it is not clear where these oscillations are initially generated. In this paper, we use a computational model to study how delta oscillations may arise in the SNr due to projections from the globus pallidus externa (GPe). We propose a network architecture that incorporates inhibition in SNr from oscillating GPe neurons and other SNr neurons. In our simulations, this configuration yields firing patterns in model SNr neurons that match those measured in vivo. In particular, we see the spontaneous emergence of near-antiphase active-predicting and inactive-predicting neural populations in the SNr, which persist under the inclusion of STN inputs based on experimental recordings. These results demonstrate how delta oscillations can propagate through BG nuclei despite imperfect oscillatory synchrony in the source site, narrowing down potential targets for the source of delta oscillations in PD models and giving new insight into the dynamics of SNr oscillations.


Assuntos
Doença de Parkinson , Parte Reticular da Substância Negra , Animais , Camundongos , Globo Pálido , Dopamina , Modelos Neurológicos , Gânglios da Base/fisiologia , Substância Negra/fisiologia
16.
Proc Natl Acad Sci U S A ; 116(43): 21602-21608, 2019 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-31591236

RESUMO

Climate change is driving the tropicalization of temperate ecosystems by shifting the range edges of numerous species poleward. Over the past few decades, mangroves have rapidly displaced salt marshes near multiple poleward mangrove range limits, including in northeast Florida. It is uncertain whether such mangrove expansions are due to anthropogenic climate change or natural climate variability. We combined historical accounts from books, personal journals, scientific articles, logbooks, photographs, and maps with climate data to show that the current ecotone between mangroves and salt marshes in northeast Florida has shifted between mangrove and salt marsh dominance at least 6 times between the late 1700s and 2017 due to decadal-scale fluctuations in the frequency and intensity of extreme cold events. Model projections of daily minimum temperature from 2000 through 2100 indicate an increase in annual minimum temperature by 0.5 °C/decade. Thus, although recent mangrove range expansion should indeed be placed into a broader historical context of an oscillating system, climate projections suggest that the recent trend may represent a more permanent regime shift due to the effects of climate change.

17.
Chaos ; 32(11): 113104, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36456317

RESUMO

This paper reports the first finding of cupolets in a chaotic Hindmarsh-Rose neural model. Cupolets (chaotic, unstable, periodic, orbit-lets) are unstable periodic orbits that have been stabilized through a particular control scheme by applying a binary control sequence. We demonstrate different neural dynamics (periodic or chaotic) of the Hindmarsh-Rose model through a bifurcation diagram where the external input current, I, is the bifurcation parameter. We select a region in the chaotic parameter space and provide the results of numerical simulations. In this chosen parameter space, a control scheme is applied when the trajectory intersects with either of the two control planes. The type of the control is determined by a bit in a binary control sequence. The control is either a small microcontrol (0) or a large macrocontrol (1) that adjusts the future dynamics of the trajectory by a perturbation determined by the coding function r ( x ). We report the discovery of many cupolets with corresponding control sequences and comment on the differences with previously reported cupolets in the double scroll system. We provide some examples of the generated cupolets and conclude by discussing potential implications for biological neurons.


Assuntos
Neurônios , Análise por Conglomerados
18.
J Pediatr Orthop ; 42(6): 314-320, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35667052

RESUMO

BACKGROUND: The optimal treatment of Gartland type IIa supracondylar humerus fractures remains controversial. We report the results of a series of patients with type IIa fractures who underwent closed reduction and immobilization using conscious sedation in the emergency department. Our goal was to identify variables associated with fractures that were successfully managed nonoperatively. METHODS: This was a retrospective cohort study of pediatric patients who underwent closed reduction of Gartland type IIa supracondylar humerus fractures with the use of conscious sedation in the emergency department. Prereduction and postreduction radiographs were reviewed to determine the degree of fracture extension, anterior humeral line index, Baumann angle, and splint flexion angle. The success of closed reduction was defined as a reduction that was maintained without the need for surgical intervention. RESULTS: A total of 54 patients (54 elbows) were included in this study. The mean overall age was 5.2±2.5 years. Following the closed reduction in the emergency department, 38 (70%) patients were successfully managed nonoperatively with casting, and 16 (30%) patients required operative intervention. The degree of fracture extension on the injury radiograph was 13.2±8.4 degrees in the nonoperative group compared with 19.8±7.5 degrees in the operative group (P=0.008). The postreduction degree of fracture extension was 3.0±3.4 degrees in the nonoperative group and 10.0±7.2 degrees in the operative group (P<0.0001). The mean anterior humeral line index on the injury radiograph was 0.34 in the nonoperative group and 0.13 in the operative group (P=0.104). The mean anterior humeral line index on the postreduction radiograph was 1.2 in the nonoperative group and 0.38 in the operative group (P=0.0002). Patient age, prereduction and postreduction Baumann angle, and the postreduction splint flexion angle did not differ significantly between groups. CONCLUSIONS: Closed reduction under conscious sedation in the emergency department is a viable treatment option for Gartland type IIa supracondylar humerus fractures. Increasing fracture extension on injury radiographs can help predict failure of nonoperative management following closed reduction. LEVEL OF EVIDENCE: Level III-retrospective comparative study.


Assuntos
Articulação do Cotovelo , Fraturas do Úmero , Criança , Pré-Escolar , Humanos , Fraturas do Úmero/cirurgia , Fraturas do Úmero/terapia , Úmero , Estudos Retrospectivos , Resultado do Tratamento , Lesões no Cotovelo
19.
Neuromodulation ; 25(5): 724-730, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35088735

RESUMO

OBJECTIVES: The use of intraoperative neuromonitoring (IONM) has been adapted to address issues of safety and proper lead positioning in spinal cord stimulation. This multicenter case series seeks to incorporate the use of evoked compound action potential (ECAP) and late response (LR) recording and compare it with the results obtained with IONM, specifically electromyography (EMG), for the confirmation of lead placement. This study aimed to establish a correlation between ECAPs, LR, and EMG and publish human recordings of ECAPs and LR during their use with IONM. MATERIALS AND METHODS: Standard neuromonitoring protocols were followed at two institutions, with two separate physicians and with seven patients, as part of a larger ongoing study registered with ClinicalTrials.gov (NCT02924129). Stimulation and recording were performed, top and bottom, on each percutaneous lead. Stimulation amplitude was increased considering ECAP, LR, and EMG thresholds. RESULTS: ECAPs, LRs, and EMG signals were observed in all patients. The onset of LR signals on implanted electrodes and EMG signal on subdermal electrodes was well correlated (rs = 0.94, p < 0.001), with a median LR:EMG value of 1.06 (N = 21). LR:EMG for the top (mean = 0.97, N = 8) vs bottom (mean = 1.15, N = 13) of the lead was compared using a paired Wilcoxon signed rank test and an independent samples Mann-Whitney test, revealing a marginally significant and a statistically significant difference (p = 0.078 and p = 0.015, respectively). Mean LR:ECAP was >2 in all locations and approximately 3.5 overall. LR:ECAP between the top and bottom of the lead was significantly different (Wilcoxon test, p < 0.01, N = 12). CONCLUSIONS: LR correlated with EMG; leads with bilateral (not necessarily symmetric) EMG activity showed LR:ECAP > 1.5. An LR:ECAP of <1, with LR/EMG generated before the ECAP, indicated that the lead is too lateral. The use of ECAP and LR has the potential of maintaining objective lead placement, without the need for needle placement with IONM.


Assuntos
Estimulação da Medula Espinal , Potenciais de Ação/fisiologia , Eletrodos Implantados , Potenciais Evocados/fisiologia , Humanos , Estudos Prospectivos , Estimulação da Medula Espinal/métodos
20.
Emerg Infect Dis ; 27(10): 2521-2528, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34545796

RESUMO

As of March 2021, coronavirus disease (COVID-19) had led to >500,000 deaths in the United States, and the state of Tennessee had the fifth highest number of cases per capita. We reviewed the Tennessee Department of Health COVID-19 surveillance and chart-abstraction data during March 15‒August 15, 2020. Patients who died from COVID-19 were more likely to be older, male, and Black and to have underlying conditions (hereafter comorbidities) than case-patients who survived. We found 30.4% of surviving case-patients and 20.3% of deceased patients had no comorbidity information recorded. Chart-abstraction captured a higher proportion of deceased case-patients with >1 comorbidity (96.3%) compared with standard surveillance deaths (79.0%). Chart-abstraction detected higher rates of each comorbidity except for diabetes, which had similar rates among standard surveillance and chart-abstraction. Investing in public health data collection infrastructure will be beneficial for the COVID-19 pandemic and future disease outbreaks.


Assuntos
COVID-19 , Pandemias , Comorbidade , Hospitalização , Humanos , Masculino , Estudos Retrospectivos , SARS-CoV-2 , Tennessee/epidemiologia , Estados Unidos/epidemiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA