146 research outputs found
Scaling and universality in the aging kinetics of the two-dimensional clock model
We study numerically the aging dynamics of the two-dimensional p-state clock
model after a quench from an infinite temperature to the ferromagnetic phase or
to the Kosterlitz-Thouless phase. The system exhibits the general scaling
behavior characteristic of non-disordered coarsening systems. For quenches to
the ferromagnetic phase, the value of the dynamical exponents, suggests that
the model belongs to the Ising-type universality class. Specifically, for the
integrated response function , we find
consistent with the value found in the two-dimensional
Ising model.Comment: 16 pages, 14 figures (please contact the authors for figures
In vitro and in vivo evaluation of In-111-DTPAGlu-G-CCK8 for cholecystokinin-B receptor imaging
Regulatory peptides and their analogs are being extensively investigated as radiopharmaceuticals for cancer imaging and
therapy. Receptors of the cholecystokinin family have been shown to be overexpressed in different types of neuroendocrine
tumors. The purposes of this study were to evaluate the cholecystokinin octapeptide amide (CCK8) peptide tagged with a
diethylenetriaminepentaacetic acid derivative (DTPAGlu) and to test whether a 111In-labeled conjugate (111In-DTPAGlu-G-CCK8,
a derivative containing the chelating agent DTPAGlu bound through a glycine linker at the N-terminal end of the bioactive
peptide CCK8) is suitable for cholecystokinin-B receptor (CCKBR) imaging. Methods: CCK8 was synthesized by solidphase
techniques and covalently coupled to DTPAGlu through a glycine linker at its amino terminus. The compound was labeled
with 111In. The radiochemical purity and stability of the compound were assessed by chromatographic methods. NIH-3T3
and A431 cells overexpressing CCKBR were used to characterize the in vitro properties of the compound. Nude mice bearing
control and CCKBR-overexpressing A431 xenografts were used as an in vivo model. Results: DTPAGlu-G-CCK8 showed
rapid and efficient labeling with 111In. The radiolabeled conjugate showed specific binding to both cell lines overexpressing
CCKBR. Binding was saturable, with a dissociation constant of 20 nmol/L in both cell systems. Both cell lines showed internalization
of the ligand after interaction with the receptor. Biodistribution studies showed rapid localization of 111In-DTPAGlu-
G-CCK8 on CCKBR-overexpressing A431 xenografts that was severalfold higher than that on control tumors at all time points
tested. Unbound activity showed rapid clearance of over 80% through the kidneys by 30 min after injection. The labeled peptide
conjugate was very stable in serum but showed a rapid breakdown after injection. Incubation with kidney homogenates
suggested that most breakdown occurred in the kidneys, favoring the clearance of unbound activity. Conclusion: Our findings
indicate that the in vitro and in vivo characteristics of 111In-DTPAGlu-G-CCK8 are favorable for CCKBR imaging, as thepeptide shows high-affinity binding to the receptor, is internalized in CCKBR-expressing cells, and shows avid uptake in CCKBR-overexpressing xenografts, with rapid clearance of unbound radioactivity through the kidneys. Furthermore, the ease of synthesis, high labeling efficiency, and chemical stability of DTPAGlu make this chelating moiety an ideal candidate for widespread use in peptide radiolabeling for nuclear medicine
applications
Development and testing of a new instrument to measure self-care in patients with osteoporosis: the self-care of osteoporosis scale
Purpose: The aim of this study was to develop and test the Self-Care of Osteoporosis Scale (SCOS), a new instrument
to measure self-care in postmenopausal women with osteoporosis.
Methods: A cross-sectional study was conducted. The SCOS was developed by a panel of experts and it was theory-driven. Confirmatory factor analysis (N = 544) was used to test the instrument’s factorial validity; Cronbach’s alpha and
McDonald’s omega were used to derive the measure’s internal consistency reliability; an intraclass correlation coefficient
was used to evaluate test-retest reliability.
Results: Confirmatory factor analysis resulted in supportive fit indices for the hypothesized three-factor structure of the
SCOS (RMSEA = 0.065; CFI = 0.99). The SCOS was demonstrated to have content validity, internal consistency and
test-retest reliability.
Conclusions: The SCOS demonstrated excellent psychometric characteristics in terms of validity and reliability. It may
be used by healthcare providers to identify if patients show lower self-care and require educational interventions
Fluctuation-Dissipation relations far from Equilibrium
In this Article we review some recent progresses in the field of
non-equilibrium linear response theory. We show how a generalization of the
fluctuation-dissipation theorem can be derived for Markov processes, and
discuss the Cugliandolo-Kurchan \cite{Cugliandolo93} fluctuation dissipation
relation for aging systems and the theorem by Franz {\it et. al.}
\cite{Franz98} relating static and dynamic properties. We than specialize the
subject to phase-ordering systems examining the scaling properties of the
linear response function and how these are determined by the behavior of
topological defects. We discuss how the connection between statics and dynamics
can be violated in these systems at the lower critical dimension or as due to
stochastic instability.Comment: 18 pages, 10 figure
Universality of the off-equilibrium response function in the kinetic Ising chain
The off-equilibrium response function and autocorrelation
function of an Ising chain with spin-exchange dynamics are studied
numerically and compared with the same quantities in the case of spin-flip
dynamics. It is found that, even though these quantities are separately
different in the two cases, the parametric plot of versus
is the same. While this result could be expected in higher
dimensionality, where is related to the equilibrium state, it is far
from trivial in the one dimensional case where this relation does not hold. The
origin of the universality of is traced back to the optimization of
domains position with respect to the perturbing external field. This mechanism
is investigated resorting to models with a single domain moving in a random
environment.Comment: 24 pages, 7 figure
Motion of Three Vortices near Collapse
A system of three point vortices in an unbounded plane has a special family
of self-similarly contracting or expanding solutions: during the motion, vortex
triangle remains similar to the original one, while its area decreases (grows)
at a constant rate. A contracting configuration brings three vortices to a
single point in a finite time; this phenomenon known as vortex collapse is of
principal importance for many-vortex systems. Dynamics of close-to-collapse
vortex configurations depends on the way the collapse conditions are violated.
Using an effective potential representation, a detailed quantitative analysis
of all the different types of near-collapse dynamics is performed when two of
the vortices are identical. We discuss time and length scales, emerging in the
problem, and their behavior as the initial vortex triangle is approaching to an
exact collapse configuration. Different types of critical behaviors, such as
logarithmic or power-law divergences are exhibited, which emphasizes the
importance of the way the collapse is approached. Period asymptotics for all
singular cases are presented as functions of the initial vortices
configurations. Special features of passive particle mixing by a near-collapse
flows are illustrated numerically.Comment: 45 pages, 22 figures Last version of the paper with all update
Impact of climate change on eucalyptus plantations in southern Brazil.
Climate change may mean significant changes in crop productivity, including for planted forests, due to changes in climatic parameters. These impacts may be more intense in some regions of the country. Scientific investigation based on field data obtained over the long term and projected scenarios are important tools for planning and decision making that can help decrease vulnerability and risk for the forest sector in the near future. Along these lines, this study (which was conducted with support from Klabin S.A., a forest-based company) indicates changes that may be on the horizon, discusses climatic behavior in some regions of Brazil which are important centers for eucalyptus production, and projects impacts on productivity and carbon emissions/removal capacity in eucalyptus forests within the scenario of climate change. A highlight of this study is the use of the HadGEM2-ES model to predict rainfall, average temperature, evapotranspiration, water deficit, frost events, and minimum temperature at 10-year intervals until 2040. This is a differential, since other studies consider longer intervals. The study indicates climatic risk and the resulting impact on eucalyptus production in southern Brazil. However, detailed investigation in the municipalities of Itapetininga, Telêmaco Borba, and Otacílio Costa points to variations in the vulnerability of these environments. The study also examines the potential of these eucalyptus forests to accumulate carbon, indicating how and to what extent this function may be affected. Predicting potential changes is an intelligent way to prepare for and even ameliorate the impacts of climate change, thus making it possible to maintain the potential for the region and eucalyptus forests to make significant contributions to environmental quality and reaffirm the opportunities that are present for the forest sector within the context of the green economy and decarbonization of the economy
Involvement of a specificity proteins-binding element in regulation of basal and estrogen-induced transcription activity of the BRCA1 gene
INTRODUCTION:Increased estrogen level has been regarded to be a risk factor for breast cancer. However, estrogen has also been shown to induce the expression of the tumor suppressor gene, BRCA1. Upregulation of BRCA1 is thought to be a feedback mechanism for controlling DNA repair in proliferating cells. Estrogens enhance transcription of target genes by stimulating the association of the estrogen receptor (ER) and related coactivators to estrogen response elements or to transcription complexes formed at activator protein (AP)-1 or specificity protein (Sp)-binding sites. Interestingly, the BRCA1 gene lacks a consensus estrogen response element. We previously reported that estrogen stimulated BRCA1 transcription through the recruitment of a p300/ER-alpha complex to an AP-1 site harbored in the proximal BRCA1 promoter. The purpose of the study was to analyze the contribution of cis-acting sites flanking the AP-1 element to basal and estrogen-dependent regulation of BRCA1 transcription.METHODS:Using transfection studies with wild-type and mutated BRCA1 promoter constructs, electromobility binding and shift assays, and DNA-protein interaction and chromatin immunoprecipitation assays, we investigated the role of Sp-binding sites and cAMP response element (CRE)-binding sites harbored in the proximal BRCA1 promoter.RESULTS:We report that in the BRCA1 promoter the AP-1 site is flanked upstream by an element (5'-GGGGCGGAA-3') that recruits Sp1, Sp3, and Sp4 factors, and downstream by a half CRE-binding motif (5'-CGTAA-3') that binds CRE-binding protein. In ER-alpha-positive MCF-7 cells and ER-alpha-negative Hela cells expressing exogenous ER-alpha, mutation of the Sp-binding site interfered with basal and estrogen-induced BRCA1 transcription. Conversely, mutation of the CRE-binding element reduced basal BRCA1 promoter activity but did not prevent estrogen activation. In combination with the AP-1/CRE sites, the Sp-binding domain enhanced the recruitment of nuclear proteins to the BRCA1 promoter. Finally, we report that the MEK1 (mitogen-activated protein kinase kinase-1) inhibitor PD98059 attenuated the recruitment of Sp1 and phosphorylated ER-alpha, respectively, to the Sp and AP-1 binding element.CONCLUSION:These cumulative findings suggest that the proximal BRCA1 promoter segment comprises cis-acting elements that are targeted by Sp-binding and CRE-binding proteins that contribute to regulation of BRCA1 transcription.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]
The role of sentinel node tumor burden in modeling the prognosis of melanoma patients with positive sentinel node biopsy: an Italian melanoma intergroup study (N = 2,086)
Background The management of melanoma patients with metastatic melanoma in the sentinel nodes (SN) is evolving based on the results of trials questioning the impact of completion lymph node dissection (CLND) and demonstrating the efficacy of new adjuvant treatments. In this landscape, new prognostic tools for fine risk stratification are eagerly sought to optimize the therapeutic path of these patients. Methods A retrospective cohort of 2,086 patients treated with CLND after a positive SN biopsy in thirteen Italian Melanoma Centers was reviewed. Overall survival (OS) was the outcome of interest; included independent variables were the following: age, gender, primary melanoma site, Breslow thickness, ulceration, sentinel node tumor burden (SNTB), number of positive SN, non-sentinel lymph nodes (NSN) status. Univariate and multivariate survival analyses were performed using the Cox proportional hazard regression model. Results The 3-year, 5-year and 10-year OS rates were 79%, 70% and 54%, respectively. At univariate analysis, all variables, except for primary melanoma body site, were found to be statistically significant prognostic factors. Multivariate Cox regression analysis indicated that older age (P < 0.0001), male gender (P = 0.04), increasing Breslow thickness (P < 0.0001), presence of ulceration (P = 0.004), SNTB size (P < 0.0001) and metastatic NSN (P < 0.0001) were independent negative predictors of OS. Conclusion The above results were utilized to build a nomogram in order to ease the practical implementation of our prognostic model, which might improve treatment personalization
Impacts of highway traffic exhaust in alpine valleys on the respiratory health in adults: a cross-sectional study
BACKGROUND: Most studies having shown respiratory health effects from traffic exhaust were conducted in urban areas with a complex mixture of air pollution sources. This study has investigated the potential impact of traffic exhaust on respiratory symptoms among adults living along a Swiss alpine highway corridor, where traffic exhaust from the respective trans-Alpine highway is the predominant source of air pollution.
METHODS: In summer 2005, we recruited 1839 adults aged 15 to 70 from a random sample of 10 communities along the Swiss alpine highway corridors. Subjects answered a questionnaire on respiratory health (asthmatic and bronchitic symptoms), risk factors, and potential confounding variables. We used logistic regression models to assess associations between respiratory symptoms and traffic exposure being defined a) as living within 200 m of the highway, and b) as a bell-shaped function simulating the decrease of pollution levels with increasing distance to the highway.
RESULTS: Positive associations were found between living close to a highway and wheezing without cold (OR = 3.10, 95%-CI: 1.27-7.55) and chronic cough (OR = 2.88, 95%-CI: 1.17-7.05). The models using a bell-shaped function suggested that symptoms reached background levels after 400-500 m from the highway. The association with chronic cough was driven by a subgroup reporting hay fever or allergic rhinitis.
CONCLUSIONS: Highway traffic exhaust in alpine highway corridors, in the absence of other industrial sources, showed negative associations with the respiratory health of adults, higher than those previously found in urban areas
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