460 research outputs found

    A Comparative Study on in Vitro Invasion Rates by Melanoma Cells in the Human Amniotic Basement Membrane Model Versus in Vivo Tumor Nodule Formation in C57BL6 Mice

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    Invasion by murine B16-F10 melanoma cells was studied using the human amniotic basement membrane (HABM) assay. B16-F10 cells were collected after a single passage through the amnion and grown to near confluency. The cycle of plating, passaging, collecting, and culturing B16-F10 cells was repeated five times. The invasion rate for B16-F10 cells remained relatively unchanged after six passages through the amnion. Injection of first-passage B16-F10 cells into C57BL6 mice resulted in 29 lung tumors per animal whereas sixth-passage cells resulted in 300+ lung tumors. While there exists no correlation of the number of cells penetrating the amnion with colonization number, lung colonization appears correlated with increased number of passages through the amnion

    Cluster Dynamics for Randomly Frustrated Systems with Finite Connectivity

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    In simulations of some infinite range spin glass systems with finite connectivity, it is found that for any resonable computational time, the saturatedenergy per spin that is achieved by a cluster algorithm is lowered in comparison to that achieved by Metropolis dynamics.The gap between the average energies obtained from these two dynamics is robust with respect to variations of the annealing schedule. For some probability distribution of the interactions the ground state energy is calculated analytically within the replica symmetry assumptionand is found to be saturated by a cluster algorithm.Comment: Revtex, 4 pages with 3 figure

    Effects of Coffee and Caffeine Anhydrous Intake During Creatine Loading

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    The purpose of this study was to determine the effect of 5 d of creatine (CRE) loading alone or in combination with caffeine anhydrous (CAF) or coffee (COF) on upper and lower body strength and sprint performance. Physically active males (n=54; Mean ± SD; Age = 20.1 ± 2.1 yrs; Weight = 78.8 ± 8.8 kg) completed baseline testing, consisting of one-repetition maximum (1RM) and repetitions to fatigue (RTF) with 80% 1RM for bench press (BP) and leg press (LP), followed by a repeated sprint test of five, 10 s sprints separated by 60 s rest on a cycle ergometer to determine peak power (PP) and total power (TP). At least 72 hr later, subjects were randomly assigned to supplement with CRE (5 g creatine monohydrate, 4 times*d−1; n=14), CRE+CAF (CRE + 300 mg*d−1 of CAF; n=13), CRE+COF (CRE + 8.9 g COF, yielding 303 mg caffeine; n=13), or placebo (PLA; n=14) for 5 d. Serum creatinine (CRN) was measured prior to and following supplementation and on day six, participants repeated pre-testing procedures. Strength measures were improved in all groups (p<0.05), with no significant time × treatment interactions. No significant interaction or main effects were observed for PP. For TP, a time × sprint interaction was observed (p<0.05), with no significant interactions between treatment groups. A time × treatment interaction was observed for serum CRN values (p<0.05) that showed increases in all groups except PLA. Four subjects reported mild gastrointestinal discomfort with CRE+CAF, with no side effects reported in other groups. These findings suggest that neither CRE alone, nor in combination with CAF or COF, significantly affected performance compared to PLA

    Dynamic Critical Behavior of the Chayes-Machta Algorithm for the Random-Cluster Model. I. Two Dimensions

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    We study, via Monte Carlo simulation, the dynamic critical behavior of the Chayes-Machta dynamics for the Fortuin-Kasteleyn random-cluster model, which generalizes the Swendsen-Wang dynamics for the q-state Potts ferromagnet to non-integer q \ge 1. We consider spatial dimension d=2 and 1.25 \le q \le 4 in steps of 0.25, on lattices up to 1024^2, and obtain estimates for the dynamic critical exponent z_{CM}. We present evidence that when 1 \le q \lesssim 1.95 the Ossola-Sokal conjecture z_{CM} \ge \beta/\nu is violated, though we also present plausible fits compatible with this conjecture. We show that the Li-Sokal bound z_{CM} \ge \alpha/\nu is close to being sharp over the entire range 1 \le q \le 4, but is probably non-sharp by a power. As a byproduct of our work, we also obtain evidence concerning the corrections to scaling in static observables.Comment: LaTeX2e, 75 pages including 26 Postscript figure

    Ground states of two-dimensional ±\pmJ Edwards-Anderson spin glasses

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    We present an exact algorithm for finding all the ground states of the two-dimensional Edwards-Anderson ±J\pm J spin glass and characterize its performance. We investigate how the ground states change with increasing system size and and with increasing antiferromagnetic bond ratio xx. We find that that some system properties have very large and strongly non-Gaussian variations between realizations.Comment: 15 pages, 21 figures, 2 tables, uses revtex4 macro

    Comparison of gene expression of metallothioneins, ubiquitin and p53 in fibroblasts from lung and skin of rats of different age

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    We studied gene expression of five metallothioneins (MT 1-5), ubiquitin and protein p53 and their products in fibroblasts culture of the skin and lungs of white rats of different ages (2 weeks, 1, 3, and 24 months) and determined its (metallothionein 1-5 types, ubiquitin, p53) product quantity. All these proteins are protective ones, but perform their functions by using different mechanisms. Metallothionein bind, transport and excrete ions of bivalent metals, ubiquitin controls the cleavage of the defective and short-lived proteins in the proteasome, protein p53 controls apoptosis, thus ensuring the genome stability. The similarity of age dynamics of gene expression of ubiquitin and MT of cells of both sources has been shown – maximum at 3 months. Expression of p53 gene has a difference: both in the skin and lungs expression increases up to 24 months. Product quantity of p53 has a minimum in the skin at 3 months and remains constant; in the lungs, this value has a maximum at 1 month

    Deriving the number of jobs in proximity services from the number of inhabitants in French rural municipalities

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    We use a minimum requirement approach to derive the number of jobs in proximity services per inhabitant in French rural municipalities. We first classify the municipalities according to their time distance to the municipality where the inhabitants go the most frequently to get services (called MFM). For each set corresponding to a range of time distance to MFM, we perform a quantile regression estimating the minimum number of service jobs per inhabitant, that we interpret as an estimation of the number of proximity jobs per inhabitant. We observe that the minimum number of service jobs per inhabitant is smaller in small municipalities. Moreover, for municipalities of similar sizes, when the distance to the MFM increases, we find that the number of jobs of proximity services per inhabitant increases.Comment: 6 pages, 5 figure

    Low Efficiency of Homology-Facilitated Illegitimate Recombination during Conjugation in Escherichia coli

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    Homology-facilitated illegitimate recombination has been described in three naturally competent bacterial species. It permits integration of small linear DNA molecules into the chromosome by homologous recombination at one end of the linear DNA substrate, and illegitimate recombination at the other end. We report that homology-facilitated illegitimate recombination also occurs in Escherichia coli during conjugation with small non-replicative plasmids, but at a low frequency of 3×10−10 per recipient cell. The fate of linear DNA in E. coli is either RecBCD-dependent degradation, or circularisation by ligation, and integration into the chromosome by single crossing-over. We also report that the observed single crossing-overs are recA-dependent, but essentially recBCD, and recFOR independent. This suggests that other, still unknown, proteins may act as mediator for the loading of RecA on DNA during single crossing-over recombination in E. coli

    Perinatal paracetamol exposure in mice does not affect the development of allergic airways disease in early life

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    Background Current data concerning maternal paracetamol intake during pregnancy, or intake during infancy and risk of wheezing or asthma in childhood is inconclusive based on epidemiological studies. We have investigated whether there is a causal link between maternal paracetamol intake during pregnancy and lactation and the development of house dust mite (HDM) induced allergic airways disease (AAD) in offspring using a neonatal mouse model. Methods Pregnant mice were administered paracetamol or saline by oral gavage from the day of mating throughout pregnancy and/or lactation. Subsequently, their pups were exposed to intranasal HDM or saline from day 3 of life for up to 6 weeks. Assessments of airway hyper-responsiveness, inflammation and remodelling were made at weaning (3 weeks) and 6 weeks of age. Results Maternal paracetamol exposure either during pregnancy and/or lactation did not affect development of AAD in offspring at weaning or at 6 weeks. There were no effects of maternal paracetamol at any time point on airway remodelling or IgE levels. Conclusions Maternal paracetamol did not enhance HDM induced AAD in offspring. Our mechanistic data do not support the hypothesis that prenatal paracetamol exposure increases the risk of childhood asthma
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