2,407 research outputs found
Adaptations to iron deficiency: cardiac functional responsiveness to norepinephrine, arterial remodeling, and the effect of beta-blockade on cardiac hypertrophy.
BackgroundIron deficiency (ID) results in ventricular hypertrophy, believed to involve sympathetic stimulation. We hypothesized that with ID 1) intravenous norepinephrine would alter heart rate (HR) and contractility, 2) abdominal aorta would be larger and more distensible, and 3) the beta-blocker propanolol would reduce hypertrophy.Methods1) 30 CD rats were fed an ID or replete diet for 1 week or 1 month. Norepinephrine was infused via jugular vein; pressure was monitored at carotid artery. Saline infusions were used as a control. The pressure trace was analyzed for HR, contractility, systolic and diastolic pressures. 2) Abdominal aorta catheters inflated the aorta, while digital microscopic images were recorded at stepwise pressures to measure arterial diameter and distensibility. 3) An additional 10 rats (5 ID, 5 control) were given a daily injection of propanolol or saline. After 1 month, the hearts were excised and weighed.ResultsEnhanced contractility, but not HR, was associated with ID hypertrophic hearts. Systolic and diastolic blood pressures were consistent with an increase in arterial diameter associated with ID. Aortic diameter at 100 mmHg and distensibility were increased with ID. Propanolol was associated with an increase in heart to body mass ratio.ConclusionsID cardiac hypertrophy results in an increased inotropic, but not chronotropic response to the sympathetic neurotransmitter, norepinephrine. Increased aortic diameter is consistent with a flow-dependent vascular remodeling; increased distensibility may reflect decreased vascular collagen content. The failure of propanolol to prevent hypertrophy suggests that ID hypertrophy is not mediated via beta-adrenergic neurotransmission
N-term 2017: Proteostasis via the N-terminus
N-term 2017 was the first international meeting to bring together researchers from diverse disciplines with a shared interest in protein N-terminal modifications and the N-end rule pathway of ubiquitin-mediated proteolysis, providing a platform for interdisciplinary cross-kingdom discussions and collaborations, as well as strengthening the visibility of this growing scientific community
Rate-dependent propagation of cardiac action potentials in a one-dimensional fiber
Action potential duration (APD) restitution, which relates APD to the
preceding diastolic interval (DI), is a useful tool for predicting the onset of
abnormal cardiac rhythms. However, it is known that different pacing protocols
lead to different APD restitution curves (RCs). This phenomenon, known as APD
rate-dependence, is a consequence of memory in the tissue. In addition to APD
restitution, conduction velocity restitution also plays an important role in
the spatiotemporal dynamics of cardiac tissue. We present new results
concerning rate-dependent restitution in the velocity of propagating action
potentials in a one-dimensional fiber. Our numerical simulations show that,
independent of the amount of memory in the tissue, waveback velocity exhibits
pronounced rate-dependence and the wavefront velocity does not. Moreover, the
discrepancy between waveback velocity RCs is most significant for small DI. We
provide an analytical explanation of these results, using a system of coupled
maps to relate the wavefront and waveback velocities. Our calculations show
that waveback velocity rate-dependence is due to APD restitution, not memory.Comment: 17 pages, 7 figure
Deep learning cardiac motion analysis for human survival prediction
Motion analysis is used in computer vision to understand the behaviour of
moving objects in sequences of images. Optimising the interpretation of dynamic
biological systems requires accurate and precise motion tracking as well as
efficient representations of high-dimensional motion trajectories so that these
can be used for prediction tasks. Here we use image sequences of the heart,
acquired using cardiac magnetic resonance imaging, to create time-resolved
three-dimensional segmentations using a fully convolutional network trained on
anatomical shape priors. This dense motion model formed the input to a
supervised denoising autoencoder (4Dsurvival), which is a hybrid network
consisting of an autoencoder that learns a task-specific latent code
representation trained on observed outcome data, yielding a latent
representation optimised for survival prediction. To handle right-censored
survival outcomes, our network used a Cox partial likelihood loss function. In
a study of 302 patients the predictive accuracy (quantified by Harrell's
C-index) was significantly higher (p < .0001) for our model C=0.73 (95 CI:
0.68 - 0.78) than the human benchmark of C=0.59 (95 CI: 0.53 - 0.65). This
work demonstrates how a complex computer vision task using high-dimensional
medical image data can efficiently predict human survival
The Health Promoting Schools Framework: Known Unknowns and an Agenda for Future Research.
The World Health Organization's Health Promoting Schools (HPS) framework is a whole-school approach to promoting health that recognizes the intrinsic relationship between health and education. Our recent Cochrane systematic review found HPS interventions produced improvements in a number of student health outcomes. Here we reflect on what this review was not able to tell us: in other words, what evidence is missing with regard to the HPS approach. Few HPS interventions engage with schools' "core business" by examining impacts on educational outcomes. Current evidence is dominated by obesity interventions, with most studies conducted with children rather than adolescents. Evidence is lacking for outcomes such as mental or sexual health, substance use, and violence. Activities to engage families and communities are currently weak and unlikely to prompt behavioral change. The HPS approach is largely absent in low-income settings, despite its potential in meeting children's basic health needs. Intervention theories are insufficiently complex, often ignoring upstream determinants of health. Few studies provide evidence on intervention sustainability or cost-effectiveness, nor in-depth contextual or process data. We set out an agenda for future school health promotion research, considering implications for key stakeholders, namely, national governments, research funders, academics, and schools
Recommended from our members
PIPITS: an automated pipeline for analyses of fungal internal transcribed spacer sequences from the Illumina sequencing platform
1. Studying fungal biodiversit y using data generated from Illumina MiSeq sequencing platforms poses a number of bioinformatic challenges with the analysis typically involving a large number of tools for each analytical step from quality filtering to generating identified operational taxonomic unit (OTU) abundance tables. 2. Here, we introduce PIPITS, an o pen-source stand-alone suite of software for automated processing of Illumina MiSeq sequences for fungal community analysis. PIPITS e xploits a number of state of the art applications to process paired-end reads from quality filtering to producing OTU abundance tables. 3. We pro vide detailed descriptions of the pipeline and show its utility in the analysis of 9 396 092 sequences generated on the MiSeq platform from Illumina MiSeq. 4. PIPITS is the first automated bioinformatics pipeline dedicated for fungal ITS sequences which incorporates ITSx to extract subregions of ITS and exploits the latest RDP Classifier to classify sequences against the curatedUNITE fungal data set
Impactos ecológicos do manejo comunitário de recursos naturais em comunidades ribeirinhas de várzea e terra firme na região de Tefé, AM
The theoretical bases of conservationism and preservation are discussed in this research, based on a field study carried out in the region of Tefé, the Middle Solimões. Twelve communities located in “Varzea” and “Terra Firme” ecosystems were studied, of which six communities have adopted a model of natural resourcemanagement, focusing on management of lakes and the other six have never participated in processes of management. The data of “Terra Firme” communities with and without management, not different from “Varzea” communities without management, in relation to perceptions of impact. The use of managed resources allowed greater control of them by the users. The model of management adopted was more appropriate to the communities in “Varzea” than in the communities of “Terra Firme”, according to the own characteristics of ecosystems.As bases teóricas do conservacionismo e do preservacionismo são discutidas neste trabalho de pesquisa, baseadas em um estudo de campo desenvolvido na região de Tefé, no Médio Solimões. Foram estudadas 12 comunidades localizadas em ecossistemas de várzea e terra firme, das quais 6 adotaram um modelo de manejo de recursos naturais, com enfoque em manejo de lagos e as outras 6 nunca participaram de processos de manejo. As percepções dos comunitários em relação aos impactos do manejo sobre o ecossistema também foram analisadas. A percepção de benefício em relação ao manejo foi fundamental para o incentivo à conservação. O modelo de manejo adotado foi mais adequado às comunidades de várzea do que para as comunidades de terra firme, em função das próprias características dos ecossistemas de Macapá e a várzea da Amazônia peruana
The development of metaphorical language comprehension in typical development and in Williams syndrome
The domain of figurative language comprehension was used to probe the developmental relation between language and cognition in typically developing individuals and individuals with Williams syndrome. Extending the work of Vosniadou and Ortony, the emergence of nonliteral similarity and category knowledge was investigated in 117 typically developing children between 4 and 12 years of age, 19 typically developing adults, 15 children with Williams syndrome between 5 and 12 years of age, and 8 adults with Williams syndrome. Participants were required to complete similarity and categorization statements by selecting one of two words (e.g., either “The sun is like ___” or “The sun is the same kind of thing as ___”) with word pairs formed from items that were literally, perceptually, or functionally similar to the target word or else anomalous (e.g., moon, orange, oven, or chair, respectively). Results indicated that individuals with Williams syndrome may access different, less abstract knowledge in figurative language comparisons despite the relatively strong verbal abilities found in this disorder
Methods and apparatus for graphical display and editing of flight plans
Systems and methods are provided for an integrated graphical user interface which facilitates the display and editing of aircraft flight-plan data. A user (e.g., a pilot) located within the aircraft provides input to a processor through a cursor control device and receives visual feedback via a display produced by a monitor. The display includes various graphical elements associated with the lateral position, vertical position, flight-plan and/or other indicia of the aircraft's operational state as determined from avionics data and/or various data sources. Through use of the cursor control device, the user may modify the flight-plan and/or other such indicia graphically in accordance with feedback provided by the display. In one embodiment, the display includes a lateral view, a vertical profile view, and a hot-map view configured to simplify the display and editing of the aircraft's flight-plan data
- …
