1,425 research outputs found
Photoreceptor Outer Segment-like Structures in Long-Term 3D Retinas from Human Pluripotent Stem Cells.
The retinal degenerative diseases, which together constitute a leading cause of hereditary blindness worldwide, are largely untreatable. Development of reliable methods to culture complex retinal tissues from human pluripotent stem cells (hPSCs) could offer a means to study human retinal development, provide a platform to investigate the mechanisms of retinal degeneration and screen for neuroprotective compounds, and provide the basis for cell-based therapeutic strategies. In this study, we describe an in vitro method by which hPSCs can be differentiated into 3D retinas with at least some important features reminiscent of a mature retina, including exuberant outgrowth of outer segment-like structures and synaptic ribbons, photoreceptor neurotransmitter expression, and membrane conductances and synaptic vesicle release properties consistent with possible photoreceptor synaptic function. The advanced outer segment-like structures reported here support the notion that 3D retina cups could serve as a model for studying mature photoreceptor development and allow for more robust modeling of retinal degenerative disease in vitro
A Model Analysis of Mechanisms for Radial Microtubular Patterns at Root Hair Initiation Sites
Plant cells have two main modes of growth generating anisotropic structures. Diffuse growth where whole cell walls extend in specific directions, guided by anisotropically positioned cellulose fibers, and tip growth, with inhomogeneous addition of new cell wall material at the tip of the structure. Cells are known to regulate these processes via molecular signals and the cytoskeleton. Mechanical stress has been proposed to provide an input to the positioning of the cellulose fibers via cortical microtubules in diffuse growth. In particular, a stress feedback model predicts a circumferential pattern of fibers surrounding apical tissues and growing primordia, guided by the anisotropic curvature in such tissues. In contrast, during the initiation of tip growing root hairs, a star-like radial pattern has recently been observed. Here, we use detailed finite element models to analyze how a change in mechanical properties at the root hair initiation site can lead to star-like stress patterns in order to understand whether a stress-based feedback model can also explain the microtubule patterns seen during root hair initiation. We show that two independent mechanisms, individually or combined, can be sufficient to generate radial patterns. In the first, new material is added locally at the position of the root hair. In the second, increased tension in the initiation area provides a mechanism. Finally, we describe how a molecular model of Rho-of-plant (ROP) GTPases activation driven by auxin can position a patch of activated ROP protein basally along a 2D root epidermal cell plasma membrane, paving the way for models where mechanical and molecular mechanisms cooperate in the initial placement and outgrowth of root hairs.This work was funded by the Knut and Alice Wallenberg Foundation via grant ShapeSystems (KAW 2012.0050) to MG and HJ, the Swedish Research Council (VR2013-4632) to HJ, and the Gatsby Charitable Foundation (GAT3395/PR4) to HJ
Arabidopsis SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity
The orientation of cell division and the coordination of cell polarity within the plane of the tissue layer (planar polarity) contribute to shape diverse multicellular organisms. The root of Arabidopsis thaliana displays regularly oriented cell divisions, cell elongation and planar polarity providing a plant model system to study these processes. Here we report that the SABRE protein, which shares similarity with proteins of unknown function throughout eukaryotes, has important roles in orienting cell division and planar polarity. SABRE localizes at the plasma membrane, endomembranes, mitotic spindle and cell plate. SABRE stabilizes the orientation of CLASP-labelled preprophase band microtubules predicting the cell division plane, and of cortical microtubules driving cell elongation. During planar polarity establishment, sabre is epistatic to clasp at directing polar membrane domains of Rho-of-plant GTPases. Our findings mechanistically link SABRE to CLASP-dependent microtubule organization, shedding new light on the function of SABRE-related proteins in eukaryotes
Motives for choosing university and specialty applicants Ukraine (for example, students NTU "KPI")
Стаття присвячена аналізу портрета абітурієнта НТУ "ХПІ", де, крім визначення мотивів професійного вибору, самооцінки особистих здібностей, розглядаються і основні цілі навчання в НТУ "ХПІ". У статті підкреслюється, що проблема професійного самовизначення стояла перед молоддю завжди, а сьогодні вона особливо актуальна, тому що сучасні умови ринку праці ведуть до того, що більшість випускників не мають ясної життєвої перспективи. Аналізуються мотиви отримання абітурієнтами вищої освіти, мотивація вступу до НТУ "ХПІ", мотиви вибору спеціальності, період формування професійного інтересу. Проаналізовано мотиви професійного вибору абітурієнтів; період формування інтересу молодих людей до обраної спеціальності (процес самовизначення, коли здійснено вибір спеціальності, ВНЗ); специфіку вибору ВНЗ (яким за рахунком був ХПІ, хто допоміг визначитися з вибором); уявлення про процес навчання в університеті; відповідність уявлень про навчання в університеті реаліям університетського життя.This article analyzes portrait applicant NTU "KPI", where in addition to determining the reasons professional choice, self-personal skills, and discusses the main goals of training at NTU "KPI". The article highlights the problem of professional self -determination was always the youth, and today it is particularly urgent because the current labor market conditions lead to the fact that most graduates do not have a clear life perspective. Analyzed the motives of applicants receiving higher education, motivation admission to NTU "KPI" motives choice of specialty, during the formation of professional interest. Analyzed the motives of professional selection of applicants; during the formation of young people's interest to the chosen profession (the process of self-selection made when specialty Universities); the specific choice of university (how the account was HPI, who helped to choose); understanding of the learning process at the university; line ideas about university studies realities of university life
A neutral Pt3 stack unsupported by any bridging ligand
Pt⋯Pt⋯Pt interactions via their d8 orbitals, combined with π–π stacking of
deprotonated, chelating 2-(3′-pyrazolyl)pyridine (pyzpy) ligands, are
responsible for trans-Pt(pyzpy)2 (2) crystallization in a stack of three
molecules unsupported by any bridging ligand
a prospective ‘before/after’ cohort study
Objectives Antibiotic resistance has risen dramatically over the past years.
For individual patients, adequate initial antibiotic therapy is essential for
clinical outcome. Computer-assisted decision support systems (CDSSs) are
advocated to support implementation of rational anti-infective treatment
strategies based on guidelines. The aim of this study was to evaluate long-
term effects after implementation of a CDSS. Design This prospective
‘before/after’ cohort study was conducted over four observation periods within
5 years. One preinterventional period (pre) was compared with three
postinterventional periods: directly after intensive implementation efforts
(post1), 2 years (post2) and 3 years (post3) after implementation. Setting
Five anaesthesiological-managed intensive care units (ICU) (one
cardiosurgical, one neurosurgical, two interdisciplinary and one intermediate
care) at a university hospital. Participants Adult patients with an ICU stay
of >48 h were included in the analysis. 1316 patients were included in the
analysis for a total of 12 965 ICU days. Intervention Implementation of a
CDSS. Outcome measures The primary end point was percentage of days with
guideline adherence during ICU treatment. Secondary end points were
antibiotic-free days and all-cause mortality compared for patients with low
versus high guideline adherence. Main results Adherence to guidelines
increased from 61% prior to implementation to 92% in post1, decreased in post2
to 76% and remained significantly higher compared with baseline in post3, with
71% (p=0.178). Additionally, antibiotic-free days increased over study
periods. At all time periods, mortality for patients with low guideline
adherence was higher with 12.3% versus 8% (p=0.014) and an adjusted OR of 1.56
(95% CI 1.05 to 2.31). Conclusions Implementation of computerised regional
adapted guidelines for antibiotic therapy is paralleled with improved
adherence. Even without further measures, adherence stayed high for a longer
period and was paralleled by reduced antibiotic exposure. Improved guideline
adherence was associated with reduced ICU mortality
Highlights from the Pierre Auger Observatory
The Pierre Auger Observatory is the world's largest cosmic ray observatory.
Our current exposure reaches nearly 40,000 km str and provides us with an
unprecedented quality data set. The performance and stability of the detectors
and their enhancements are described. Data analyses have led to a number of
major breakthroughs. Among these we discuss the energy spectrum and the
searches for large-scale anisotropies. We present analyses of our X
data and show how it can be interpreted in terms of mass composition. We also
describe some new analyses that extract mass sensitive parameters from the 100%
duty cycle SD data. A coherent interpretation of all these recent results opens
new directions. The consequences regarding the cosmic ray composition and the
properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray
Conference, Rio de Janeiro 201
The Pierre Auger Observatory III: Other Astrophysical Observations
Astrophysical observations of ultra-high-energy cosmic rays with the Pierre
Auger ObservatoryComment: Contributions to the 32nd International Cosmic Ray Conference,
Beijing, China, August 201
A search for point sources of EeV photons
Measurements of air showers made using the hybrid technique developed with
the fluorescence and surface detectors of the Pierre Auger Observatory allow a
sensitive search for point sources of EeV photons anywhere in the exposed sky.
A multivariate analysis reduces the background of hadronic cosmic rays. The
search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an
energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been
detected. An upper limit on the photon flux has been derived for every
direction. The mean value of the energy flux limit that results from this,
assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial
direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in
which EeV cosmic ray protons are emitted by non-transient sources in the
Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical
Journa
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