415 research outputs found
The Effects of Retinoic Acid and Butyric Acid on in vitro Migration by Murine B16a Cells: A Quantitative Scanning Electron Microscopic Study
Retinoic acid (RA) and butyric acid (BA) were investigated for their effect on in vitro migration of highly metastatic murine B16a melanoma cells. These potential antitumor agents are known to alter the cytoskeleton. Our initial studies determined the 72 h cytostatic /cytotoxic concentration of RA (1 X 10-6 M / \u3e 1 X 10-5M) and BA (1.5 mM) / \u3e 2.0 mM). Cytostasis by RA and BA was confirmed by autoradiography and radioisotope incorporation. For migration assays, cells were plated on 3 and 5 μm diameter pore polycarbonate membranes. Complete media was added containing RA or BA at time of plating. For BA pretreatment studies, BA was added to cells for 72 h prior to plating cells in fresh BA on the membranes. Top and bottom surfaces of the membranes were examined after 72 h of incubation by scanning electron microscopy. Al though RA and BA induced cells on top of the membrane to change morphology as shown by phase, transmission and scanning electron microscopy, only BA enhanced the deformability of cells to allow for passage through the 3 μm diameter pores. Butyric acid enhanced migration through 3 μm diameter pore membranes by 511%. For 5 μm diameter pore membranes, 55.2% of the plated number of untreated early passage cells migrated to the bottom surface as compared to 57.3% for BA-treated cells and 14.9% for RA-treated cells. However, if cellular proliferation over the 72 h period was factored in, BA increased migration by 456% over the controls and pretreatment of cells with BA for 72 h prior to plating increased migration by 893%. Without considering proliferation, RA inhibited migration by 75% over controls. The decrease in migration observed in RA-treated cells was due to an inhibitory effect on cellular migration and a decrease in proliferation
Effects of Coffee and Caffeine Anhydrous Intake During Creatine Loading
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
Mean Field Behavior of Cluster Dynamics
The dynamic behavior of cluster algorithms is analyzed in the classical mean
field limit. Rigorous analytical results below establish that the dynamic
exponent has the value for the Swendsen-Wang algorithm and
for the Wolff algorithm.
An efficient Monte Carlo implementation is introduced, adapted for using
these algorithms for fully connected graphs. Extensive simulations both above
and below demonstrate scaling and evaluate the finite-size scaling
function by means of a rather impressive collapse of the data.Comment: Revtex, 9 pages with 7 figure
Dynamical Scaling from Multi-Scale Measurements
We present a new measure of the Dynamical Critical behavior: the "Multi-scale
Dynamical Exponent (MDE)"Comment: 9 pages,Latex, Request figures from [email protected]
Dynamic Critical Behavior of the Chayes-Machta Algorithm for the Random-Cluster Model. I. Two Dimensions
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 J Edwards-Anderson spin glasses
We present an exact algorithm for finding all the ground states of the
two-dimensional Edwards-Anderson spin glass and characterize its
performance. We investigate how the ground states change with increasing system
size and and with increasing antiferromagnetic bond ratio . 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
Deriving the number of jobs in proximity services from the number of inhabitants in French rural municipalities
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
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
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