749 research outputs found
Functional status and quality of life in patients suffering severe cranioencephalic trauma at the time of discharge from the intensive care unit and 1 year after
CHK1 expression in gastric cancer is modulated by p53 and RB1/E2F1: Implications in chemo/radiotherapy response
Radiation has a limited but relevant role in the adjuvant therapy of gastric cancer (GC) patients. Since Chk1 plays a critical function in cellular response to genotoxic agents, we aimed to analyze the role of Chk1 in GC as a biomarker for radiotherapy resistance. We analyzed Chk1 expression in AGS and MKN45 human GC cell lines by RT-QPCR and WB and in a small cohort of human patientâs samples. We demonstrated that Chk1 overexpression specifically increases resistance to radiation in GC cells. Accordingly, abrogation of Chk1 activity with UCN-01 and its expression with shChk1 increased sensitivity to bleomycin and radiation. Furthermore, when we assessed Chk1 expression in human samples, we found a correlation between nuclear Chk1 accumulation and a decrease in progression free survival. Moreover, using a luciferase assay we found that Chk1âs expression is controlled by p53 and RB/E2F1 at the transcriptional level. Additionally, we present preliminary data suggesting a posttranscriptional regulation mechanism, involving miR-195 and miR-503, which are inversely correlated with expression of Chk1 in radioresistant cells. In conclusion, Chk1/microRNA axis is involved in resistance to radiation in GC, and suggests Chk1 as a potential tool for optimal stratification of patients susceptible to receive adjuvant radiotherapy after surgeryThis work was supported by Instituto de Salud Carlos IIIâFondo de InvestigaciĂłn Sanitaria (PS09/1988 to ISP; PI11-00949, pI014-1495 and Feder Funds to RP); Comunidad AutĂłnoma de Madrid-Universidad AutĂłnoma de Madrid (CCG10-UAM/BIO-5871 to ISP); FundaciĂłn Leticia Castillejo Castillo and Ministerio de Ciencia e InnovaciĂłn (SAF2012-30862 to RSP), Spain
Paper-based chromatic toxicity bioassay by analysis of bacterial ferricyanide reduction
Water quality assessment requires a continuous and strict analysis of samples to guarantee compliance with established standards. Nowadays, the increasing number of pollutants and their synergistic effects lead to the development general toxicity bioassays capable to analyse water pollution as a whole. Current general toxicity methods, e.g. MicrotoxŸ, rely on long operation protocols, the use of complex and expensive instrumentation and sample pre-treatment, which should be transported to the laboratory for analysis. These requirements delay sample analysis and hence, the response to avoid an environmental catastrophe. In an attempt to solve it, a fast (15 min) and low-cost toxicity bioassay based on the chromatic changes associated to bacterial ferricyanide reduction is here presented. E. coli cells (used as model bacteria) were stably trapped on low-cost paper matrices (cellulose-based paper discs, PDs) and remained viable for long times (1 month at -20 °C). Apart from bacterial carrier, paper matrices also acted as a fluidic element, allowing fluid management without the need of external pumps. Bioassay evaluation was performed using copper as model toxic agent. Chromatic changes associated to bacterial ferricyanide reduction were determined by three different transduction methods, i.e. (i) optical reflectometry (as reference method), (ii) image analysis and (iii) visual inspection. In all cases, bioassay results (in terms of half maximal effective concentrations, EC50) were in agreement with already reported data, confirming the good performance of the bioassay. The validation of the bioassay was performed by analysis of real samples from natural sources, which were analysed and compared with a reference method (i.e. Microtox). Obtained results showed agreement for about 70% of toxic samples and 80% of non-toxic samples, which may validate the use of this simple and quick protocol in the determination of general toxicity. The minimum instrumentation requirements and the simplicity of the bioassay open the possibility of in-situ water toxicity assessment with a fast and low-cost protocolPostprint (author's final draft
Continuously-variable survival exponent for random walks with movable partial reflectors
We study a one-dimensional lattice random walk with an absorbing boundary at
the origin and a movable partial reflector. On encountering the reflector, at
site x, the walker is reflected (with probability r) to x-1 and the reflector
is simultaneously pushed to x+1. Iteration of the transition matrix, and
asymptotic analysis of the probability generating function show that the
critical exponent delta governing the survival probability varies continuously
between 1/2 and 1 as r varies between 0 and 1. Our study suggests a mechanism
for nonuniversal kinetic critical behavior, observed in models with an infinite
number of absorbing configurations.Comment: 5 pages, 3 figure
Mapping of the human visual cortex using image-guided transcranial magnetic stimulation
We describe a protocol using transcranial magnetic stimulation (TMS) to systematically map the visual sensations induced by focal and
non-invasive stimulation of the human occipital cortex. TMS is applied with a figure of eight coil to 28 positions arranged in a 232-cm
grid over the occipital area. A digitizing tablet connected to a PC computer running customized software, and audio and video recording
are used for detailed and accurate data collection and analysis of evoked phosphenes. A frameless image-guided neuronavigational device
is used to describe the position of the actual sites of the stimulation coils relative to the cortical surface. Our results show that TMS is able
to elicit phosphenes in almost all sighted subjects and in a proportion of blind subjects. Evoked phosphenes are topographically organized.
Despite minor inter-individual variations, the mapping results are reproducible and show good congruence among different subjects. This
procedure has potential to improve our understanding of physiologic organization and plastic changes in the human visual system and to
establish the degree of remaining functional visual cortex in blind subjects. Such a non-invasive method is critical for selection of suitable
subjects for a cortical visual prosthesis.This research has been carried out with financial support from the Commission of the European Communities, specific RTD programme âQuality of Life and Management of Living Resourcesâ, QLK6-CT-2001-00279 and by the Ministerio de Ciencia y Tecnologıa(MAT2000-1049)Fondo de Investigaciones de la Seguridad Social (FISS 01-0674)National Institute of Mental Health (MH60734, MH57980)National Eye Institute (EYEY12091)Harvard-Thorndike General Clinical Research Center at Beth Israel Deaconess Medical Center (NCRR MO1 RR01032).Medicin
An in-depth view of the microscopic dynamics of Ising spin glasses at fixed temperature
Using the dedicated computer Janus, we follow the nonequilibrium dynamics of
the Ising spin glass in three dimensions for eleven orders of magnitude. The
use of integral estimators for the coherence and correlation lengths allows us
to study dynamic heterogeneities and the presence of a replicon mode and to
obtain safe bounds on the Edwards-Anderson order parameter below the critical
temperature. We obtain good agreement with experimental determinations of the
temperature-dependent decay exponents for the thermoremanent magnetization.
This magnitude is observed to scale with the much harder to measure coherence
length, a potentially useful result for experimentalists. The exponents for
energy relaxation display a linear dependence on temperature and reasonable
extrapolations to the critical point. We conclude examining the time growth of
the coherence length, with a comparison of critical and activated dynamics.Comment: 38 pages, 26 figure
Matching microscopic and macroscopic responses in glasses
We first reproduce on the Janus and Janus II computers a milestone experiment
that measures the spin-glass coherence length through the lowering of
free-energy barriers induced by the Zeeman effect. Secondly we determine the
scaling behavior that allows a quantitative analysis of a new experiment
reported in the companion Letter [S. Guchhait and R. Orbach, Phys. Rev. Lett.
118, 157203 (2017)]. The value of the coherence length estimated through the
analysis of microscopic correlation functions turns out to be quantitatively
consistent with its measurement through macroscopic response functions.
Further, non-linear susceptibilities, recently measured in glass-forming
liquids, scale as powers of the same microscopic length.Comment: 6 pages, 4 figure
Uso do cobre no controle da verminose gastrintestinal em ovinos.
No RS, a prevalĂȘncia de resistĂȘncia anti-helmĂntica nos rebanhos ovinos representa um grave problema para o controle eficiente das helmintoses gastrintestinais. A resistĂȘncia anti-helmĂntica em nematĂłdeos de ovinos se constitui no principal problema sanitĂĄrio com que se defronta a indĂșstria ovinĂcola no Brasil'. Esta situação nĂŁo Ă© diferente em outros paĂses onde a resistĂȘncia dos parasitos Ă maioria dos grupos quĂmicos Ă© uma realidade. Devido a estes fatores, vĂĄrios estudos vem sendo realizados visando o desenvolvimento de mĂ©todos alternativos que contribuam para reduzir o consumo do uso de anti-helmĂnticos no controle da gastroenterite verminĂłtica, como o uso de fungos nematĂłfagose o emprego de minerais, cobre, como exemplo. Assim, pesquisadores da Nova ZelĂąndia, relataram que a administração oral de partĂculas de Ăłxido de cobre (COWP) para ovinos proporcionava uma redução significativa no nĂșmero de parasitos recuperados na necropsia, com uma redução de 96% para Haemonchus. contortus.e 56% para Ostertagia circumcincta, respectivamente, alĂ©m disso, aumento da mortalidade e redução da fecundidade de fĂȘmeas de H. contortus tambĂ©m tem sido relatado, bem como, beneficios no combate de parasitos abomasals '. Este estudo teve o objetivo de verificar o tempo de proteção do cobre contra reinfecçÔes por helmintos gastrintestinais de ovinos em pastejo para possĂvel incorporação como ferramenta alternativa de controle
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