1,432 research outputs found
Using stem cells in skin regeneration: possibilities and reality
Tissue-engineered skin has a long history of clinical applications, yet current treatments are not capable of completely regenerating normal, uninjured skin. Nonetheless, the field has experienced a tremendous development in the past 10 years, encountering the summit of tissue engineering (TE) and the arising of stem cell research. Since then, unique features of these cells such as self-renewal capacity, multi-lineage differentiation potential, and wound healing properties have been highlighted. However, a realistic perspective of their outcome in skin regenerative medicine applications is still absent. This review intends to discuss the directions that adult and embryonic stem cells (ESCs) can take, strengthening the skin regeneration field. Distinctively, a critical overview of stem cellsâ differentiation potential onto skin main lineages, along with a highlight of their participation in wound healing mechanisms, is herein provided. We aim to compile and review significant work to allow a better understanding of the best skin TE approaches, enabling the embodiment of the materialization of a new era in skin regeneration to come, with a conscious overview of the current limitations
ISO spectroscopy of gas and dust: from molecular clouds to protoplanetary disks
Observations of interstellar gas-phase and solid-state species in the 2.4-200
micron range obtained with the spectrometers on board the Infrared Space
Observatory are reviewed. Lines and bands due to ices, polycyclic aromatic
hydrocarbons, silicates and gas-phase atoms and molecules (in particular H2,
CO, H2O, OH and CO2) are summarized and their diagnostic capabilities
illustrated. The results are discussed in the context of the physical and
chemical evolution of star-forming regions, including photon-dominated regions,
shocks, protostellar envelopes and disks around young stars.Comment: 56 pages, 17 figures. To appear in Ann. Rev. Astron. Astrophys. 2004.
Higher resolution version posted at
http://www.strw.leidenuniv.nl/~ewine/araa04.pd
Oral Administration of GW788388, an Inhibitor of Transforming Growth Factor Beta Signaling, Prevents Heart Fibrosis in Chagas Disease
Cardiac damage and dysfunction are prominent features in patients with chronic Chagas disease, which is caused by infection with the protozoan parasite Trypanosoma cruzi (T. cruzi) and affects 10–12 million individuals in South and Central America. Our group previously reported that transforming growth factor beta (TGFß) is implicated in several regulatory aspects of T. cruzi invasion and growth and in host tissue fibrosis. In the present work, we evaluated the therapeutic action of an oral inhibitor of TGFß signaling (GW788388) administered during the acute phase of experimental Chagas disease. GW788388 treatment significantly reduced mortality and decreased parasitemia. Electrocardiography showed that GW788388 treatment was effective in protecting the cardiac conduction system, preserving gap junction plaque distribution and avoiding the development of cardiac fibrosis. Inhibition of TGFß signaling in vivo appears to potently decrease T. cruzi infection and to prevent heart damage in a preclinical mouse model. This suggests that this class of molecules may represent a new therapeutic tool for acute and chronic Chagas disease that warrants further pre-clinical exploration. Administration of TGFß inhibitors during chronic infection in mouse models should be further evaluated, and future clinical trials should be envisaged
Polymorphism analysis of the CTLA-4 gene in paracoccidioidomycosis patients
The CTLA-4 protein is expressed in activated T cells and plays an essential role in the immune response through its regulatory effect on T cell activation. Polymorphisms of the CTLA-4 gene have been correlated with autoimmune, neoplastic and infectious illnesses. This work aimed to verify possible associations between single nucleotide polymorphisms (SNPs) in CTLA-4, -318C/T in the promoter and +49A/G in exon 1 and paracoccidioidomycosis (PCM) caused by Paracoccidioides brasiliensis. For this purpose, 66 chronic form PCM patients and 76 healthy controls had their allele, genotype and haplotype frequencies determined. The genetic admixture structure of the patients and controls was evaluated to eliminate ancestral bias. The comparison of frequencies indicated no significant differences between patients and controls that could link the SNPs to PCM. Groups were admixture matched with no difference observed in population ancestry inference, indicating that the absence of association between CTLA-4 polymorphisms and PCM could not be attributed to ancestral bias. This study showed that there was no association between the CTLA-4 SNPs -318 and +49 and the resistance or susceptibility to PCM
In vitro activity of daptomycin, linezolid and rifampicin on Staphylococcus epidermidis biofilms
Owing to their massive use, Staphylococcus
epidermidis has recently developed significant resistance to
several antibiotics, and became one of the leading causes of
hospital-acquired infections. Current antibiotics are typically
ineffective in the eradication of bacteria in biofilmassociated
persistent infections. Accordingly, the paucity
of effective treatment against cells in this mode of growth
is a key factor that potentiates the need for new agents
active in the prevention or eradication of biofilms. Daptomycin
and linezolid belong to the novel antibiotic therapies
that are active against gram-positive cocci. On the other
hand, rifampicin has been shown to be one of the most
potent, prevalent antibiotics against S. epidermidis biofilms.
Therefore, the main aim of this study was to study
the susceptibility of S. epidermidis biofilm cells to the two
newer antimicrobial agents previously mentioned, and
compare the results obtained with the antimicrobial effect
of rifampicin, widely used in the prevention/treatment of
indwelling medical device infections. To this end the in
vitro activities of daptomycin, linezolid, and rifampicin on
S. epidermidis biofilms were accessed, using these antibiotics
at MIC and peak serum concentrations. The results
demonstrated that at MIC concentration, rifampicin was the
most effective antibiotic tested. At peak serum concentration,
both strains demonstrated similar susceptibility to
rifampicin and daptomycin, with colony-forming units
(CFUs) reductions of approximately 3–4 log10, with a
slightly lower response to linezolid, which was also more
strain dependent. However, considering all the parameters
studied, daptomycin was considered the most effective
antibiotic tested, demonstrating an excellent in vitro
activity against S. epidermidis biofilm cells. In conclusion,
this antibiotic can be strongly considered as an acceptable
therapeutic option for S. epidermidis biofilm-associated
infections and can represent a potential alternative to rifampicin
in serious infections where rifampicin resistance
becomes prevalent.Bruna Leite acknowledges the financial support from ISAC/Program Erasmus Munds External Cooperation and the IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Campus of Gualtar. Fernanda Gomes and Pilar Teixeira fully acknowledge the financial support from Fundacao para a Ciencia e Tecnologia (FCT) through the grants SFRH/BD/32126/2006 and SFRH/BPD/26803/2006, respectively
Interaction Between Convection and Pulsation
This article reviews our current understanding of modelling convection
dynamics in stars. Several semi-analytical time-dependent convection models
have been proposed for pulsating one-dimensional stellar structures with
different formulations for how the convective turbulent velocity field couples
with the global stellar oscillations. In this review we put emphasis on two,
widely used, time-dependent convection formulations for estimating pulsation
properties in one-dimensional stellar models. Applications to pulsating stars
are presented with results for oscillation properties, such as the effects of
convection dynamics on the oscillation frequencies, or the stability of
pulsation modes, in classical pulsators and in stars supporting solar-type
oscillations.Comment: Invited review article for Living Reviews in Solar Physics. 88 pages,
14 figure
Asteroseismology and Interferometry
Asteroseismology provides us with a unique opportunity to improve our
understanding of stellar structure and evolution. Recent developments,
including the first systematic studies of solar-like pulsators, have boosted
the impact of this field of research within Astrophysics and have led to a
significant increase in the size of the research community. In the present
paper we start by reviewing the basic observational and theoretical properties
of classical and solar-like pulsators and present results from some of the most
recent and outstanding studies of these stars. We centre our review on those
classes of pulsators for which interferometric studies are expected to provide
a significant input. We discuss current limitations to asteroseismic studies,
including difficulties in mode identification and in the accurate determination
of global parameters of pulsating stars, and, after a brief review of those
aspects of interferometry that are most relevant in this context, anticipate
how interferometric observations may contribute to overcome these limitations.
Moreover, we present results of recent pilot studies of pulsating stars
involving both asteroseismic and interferometric constraints and look into the
future, summarizing ongoing efforts concerning the development of future
instruments and satellite missions which are expected to have an impact in this
field of research.Comment: Version as published in The Astronomy and Astrophysics Review, Volume
14, Issue 3-4, pp. 217-36
Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV
The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration
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