3,717 research outputs found
Reduction of leukocyte microvascular adherence and preservation of blood-brain barrier function by superoxide-lowering therapies in a piglet model of neonatal asphyxia
Background: Asphyxia is the most common cause of brain damage in newborns. Substantial evidence indicates that leukocyte recruitment in the cerebral vasculature during asphyxia contributes to this damage. We tested the hypothesis that superoxide radical (O2⋅_) promotes an acute post-asphyxial inflammatory response and blood-brain barrier (BBB) breakdown. We investigated the effects of removing O2⋅_ by superoxide dismutase (SOD) or C3, the cell-permeable SOD mimetic, in protecting against asphyxia-related leukocyte recruitment. We also tested the hypothesis that xanthine oxidase activity is one source of this radical.Methods: Anesthetized piglets were tracheostomized, ventilated, and equipped with closed cranial windows for the assessment of post-asphyxial rhodamine 6G-labeled leukocyte-endothelial adherence and microvascular permeability to sodium fluorescein in cortical venules. Asphyxia was induced by discontinuing ventilation. SOD and C3 were administered by cortical superfusion. The xanthine oxidase inhibitor oxypurinol was administered intravenously.Results: Leukocyte-venular adherence significantly increased during the initial 2 h of post-asphyxial reperfusion. BBB permeability was also elevated relative to non-asphyxial controls. Inhibition of O2⋅_ production by oxypurinol, or elimination of O2⋅_ by SOD or C3, significantly reduced rhodamine 6G-labeled leukocyte-endothelial adherence and improved BBB integrity, as measured by sodium fluorescein leak from cerebral microvessels.Conclusion: Using three different strategies to either prevent formation or enhance elimination of O2⋅_ during the post-asphyxial period, we saw both reduced leukocyte adherence and preserved BBB function with treatment. These findings suggest that agents which lower O2⋅_ in brain may be attractive new therapeutic interventions for the protection of the neonatal brain following asphyxia
Left ventricular clefts - incidental finding or pathologic sign of Wilson's disease?
Background: Wilson’s disease is an inherited autosomal recessive multi-systemic disorder characterized by reduced
excretion and consequently excessive accumulation of copper in different organs, such as the heart.
Results: In a prospective controlled trial, which is the largest to date, we evaluated 61 patients with Wilson’s
disease, age- and sex-matched to 61 healthy patients, for cardiac manifestation using cardiac magnetic resonance
imaging. Patients were under stable disease and had no signs of heart failure at the time of examination.
We detected a left ventricular cleft, an invagination penetrating more than 50% wall thickness of the adjoining
compact myocardium in diastole, in 20% of the patients (12 out of 61) compared to 5% among control patients (3
out of 61, p = 0.013). No correlation between the incidence of cleft and a certain genotype of Wilson’s disease was
found. All described cases were incidental findings and none of the patients showed other signs of cardiac
involvement.
Conclusions: To conclude, the results of this study suggests that the increased occurrence of left ventricular clefts
is due to Wilson’s disease. Large studies with a long observation period are needed for further evaluation
A discrete slug population model determined by egg production
Slugs are significant pests in agriculture (as well as a nuisance to gardeners), and it is therefore important to understand their population dynamics for the construction of efficient and effective control measures. Differential equation models of slug populations require the inclusion of large (variable) temporal delays, and strong seasonal forcing results in a non-autonomous system. This renders such models open to only a limited amount of rigorous analysis. In this paper, we derive a novel batch model based purely upon the quantity of eggs produced at different times of the year. This model is open to considerable reduction; from the resulting two variable discrete-time system it is possible to reconstruct the dynamics of the full population across the year and give conditions for extinction or global stability and persistence. Furthermore, the steady state temporal population distribution displays qualitatively different behavior with only small changes in the survival probability of slugs. The model demonstrates how small variations in the favorability of different years may result in widely different slug population fluctuations between consecutive years, and is in good agreement with field data
What Does an Exemplary Middle School Mathematics Teacher Look Like? The Use of a Professional Development Rubric
A School University Research Network (SURN) committee composed of current mathematics teachers, central office math supervisors, building administrators, mathematicians, and mathematics educators researched numerous sources regarding best practices in mathematics instruction. The resulting professional development rubric synthesizes their findings and can serve a professional development role by providing teachers and administrators with a tool to develop clarity and consensus on best mathematics instructional practices, and how these practices are implemented in the classroom. It is also being used as a tool for cooperating teachers in their supervision of student teachers and as a reflective method for self-evaluation
The Use of Maleic Hydrazide for Effective Hybridization of Setaria viridis
An efficient method for crossing green foxtail (Setaria viridis) is currently lacking. S. viridis is considered to be the new model plant for the study of C4 system in monocots and so an effective crossing protocol is urgently needed. S. viridis is a small grass with C4-NADP (ME) type of photosynthesis and has the advantage of having small genome of about 515 Mb, small plant stature, short life cycle, multiple tillers, and profuse seed set, and hence is an ideal model species for research. The objectives of this project were to develop efficient methods of emasculation and pollination, and to speed up generation advancement. We assessed the response of S. viridis flowers to hot water treatment (48°C) and to different concentrations of gibberellic acid, abscisic acid, maleic hydrazide (MH), and kinetin. We found that 500 μM of MH was effective in the emasculation of S. viridis, whilst still retaining the receptivity of the stigma to pollination. We also report effective ways to accelerate the breeding cycle of S. viridis for research through the germination of mature as well as immature seeds in optimized culture media. We believe these findings will be of great interest to researchers using Setaria
TANAMI - Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry
We present a summary of the observation strategy of TANAMI (Tracking Active
Galactic Nuclei with Austral Milliarcsecond Interferometry), a monitoring
program to study the parsec-scale structure and dynamics of relativistic jets
in active galactic nuclei (AGN) of the Southern Hemisphere with the Australian
Long Baseline Array (LBA) and the trans-oceanic antennas Hartebeesthoek, TIGO,
and O'Higgins. TANAMI is focusing on extragalactic sources south of -30 degrees
declination with observations at 8.4 GHz and 22 GHz every ~2 months at
milliarcsecond resolution. The initial TANAMI sample of 43 sources has been
defined before the launch of the Fermi Gamma Ray Space Telescope to include the
most promising candidates for bright gamma-ray emission to be detected with its
Large Area Telescope (LAT). Since November 2008, we have been adding new
sources to the sample, which now includes all known radio- and gamma-ray bright
AGN of the Southern Hemisphere. The combination of VLBI and gamma-ray
observations is crucial to understand the broadband emission characteristics of
AGN and the nature of relativistic jets.Comment: Conference proceedings "2009 Fermi Symposium" eConf Proceedings
C09112
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