bluuebunny/crossref_metadata_2025 huggingface dataset:
Coupled Atomistic/Discrete Dislocation Simulations of Nanoindentation at Finite Temperature
Authors: Shiari Behrouz , Miller Ronald E. , Curtin William A.
Published: September 2005

Simulations of nanoindentation in single crystals are performed using a finite temperature coupled atomistic/continuum discrete dislocation (CADD) method. This computational method for multiscale modeling of plasticity has the ability of treating dislocations as either atomistic or continuum entities within a single computational framework. The finite-temperature approach here inserts a Nose-Hoover thermostat to control the instantaneous fluctuations of temperature inside the atomistic region during the indentation process. The method of thermostatting the atomistic region has a significant role on mitigating the reflected waves from the atomistic/continuum boundary and preventing the region beneath the indenter from overheating. The method captures, at the same time, the atomistic mechanisms and the long-range dislocation effects without the computational cost of full atomistic simulations. The effects of several process variables are investigated, including system temperature and rate of indentation. Results and the deformation mechanisms that occur during a series of indentation simulations are discussed.
Pseudoelasticity of Single Crystalline Cu Nanowires Through Reversible Lattice Reorientations
Authors: Liang Wuwei , Zhou Min
Published: September 2005

Molecular dynamics simulations are carried out to analyze the structure and mechanical behavior of Cu nanowires with lateral dimensions of 1.45–2.89 nm. The calculations simulate the formation of nanowires through a “top-down” fabrication process by “slicing” square columns of atoms from single-crystalline bulk Cu along the [001], [010], and [100] directions and by allowing them to undergo controlled relaxation which involves the reorientation of the initial configuration with a ⟨001⟩ axis and {001} surfaces into a new configuration with a ⟨110⟩ axis and {111} lateral surfaces. The propagation of twin planes is primarily responsible for the lattice rotation. The transformed structure is the same as what has been observed experimentally in Cu nanowires. A pseudoelastic behavior driven by the high surface-to-volume ratio and surface stress at the nanoscale is observed for the transformed wires. Specifically, the relaxed wires undergo a reverse transformation to recover the configuration it possessed as part of the bulk crystal prior to relaxation when tensile loading with sufficient magnitude is applied. The reverse transformation progresses with the propagation of a single twin boundary in reverse to that observed during relaxation. This process has the diffusionless nature and the invariant-plane strain of a martensitic transformation and is similar to those in shape memory alloys in phenomenology. The reversibility of the relaxation and loading processes endows the nanowires with the ability for pseudoelastic elongations of up to 41% in reversible axial strain which is well beyond the yield strain of the approximately 0.25% of bulk Cu and the recoverable strains on the order of 8% of most bulk shape memory materials. The existence of the pseudoelasticity observed in the single-crystalline, metallic nanowires here is size and temperature dependent. At 300 K, this effect is observed in wires with lateral dimensions equal to or smaller than 1.81×1.81nm. As temperature increases, the critical wire size for observing this effect increases. This temperature dependence gives rise to a novel shape memory effect to Cu nanowires not seen in bulk Cu.
Interactions of Carbon Atoms and Dimer Vacancies on the Si(001)
Surface
Authors: Ciobanu Cristian V. , Barbu Adrian , Briggs Ryan M.
Published: September 2005

We investigate the interactions between substitutional carbon atoms on the defect free, (2×1) reconstructed Si(001) surface, and bring evidence that the interaction energy differs significantly from the inverse-cube distance dependence that is predicted by the theory of force dipoles on an elastic half-space. Based on Tersoff potentials, we also calculate the interactions between carbon atoms and dimer vacancies. The calculations indicate that dimer vacancies (DVs) are strongly stabilized by fourth-layer C atoms placed directly underneath them. By use of simple model Monte Carlo simulations, we show that the computed interactions between carbon atoms and DVs lead to self-assembled vacancy lines, in qualitative agreement with recent experimental results.
Structure of PTB Bound to RNA: Specific Binding and Implications for Splicing Regulation
Authors: Oberstrass Florian C. , Auweter Sigrid D. , Erat Michèle , Hargous Yann , Henning Anke , Wenter Philipp , Reymond Luc , Amir-Ahmady Batoul , Pitsch Stefan , Black Douglas L. , Allain Frédéric H.-T.
Published: September 2005

The polypyrimidine tract binding protein (PTB) is a 58-kilodalton RNA binding protein involved in multiple aspects of messenger RNA metabolism, including the repression of alternative exons. We have determined the solution structures of the four RNA binding domains (RBDs) of PTB, each bound to a CUCUCU oligonucleotide. Each RBD binds RNA with a different binding specificity. RBD3 and RBD4 interact, resulting in an antiparallel orientation of their bound RNAs. Thus, PTB will induce RNA looping when bound to two separated pyrimidine tracts within the same RNA. This leads to structural models for how PTB functions as an alternative-splicing repressor.
A Chromium Terephthalate-Based Solid with Unusually Large Pore Volumes and Surface Area
Authors: Férey G. , Mellot-Draznieks C. , Serre C. , Millange F. , Dutour J. , Surblé S. , Margiolaki I.
Published: September 2005

We combined targeted chemistry and computational design to create a crystal structure for porous chromium terephthalate, MIL-101, withverylargeporesizes and surface area. Its zeotype cubic structure has a giant cell volume (∼702,000 cubic angstroms), a hierarchy of extra-large pore sizes (∼30 to 34 angstroms), and a Langmuir surface area for N
2
of ∼5900 ± 300 square meters per gram. Beside the usual properties of porous compounds, this solid has potential as a nanomold for monodisperse nanomaterials, as illustrated here by the incorporation of Keggin polyanions within the cages.
Fluorescent Guest Molecules Report Ordered Inner Phase of Host Capsules in Solution
Authors: Dalgarno Scott J. , Tucker Sheryl A. , Bassil Daniel B. , Atwood Jerry L.
Published: September 2005

Despite recent strides in the synthesis of elaborate nanometer-scale molecular hosts, the internal structure of these self-assembled cages remains ill characterized. We used fluorescent probe molecules, pyrene butyric acid (PBA), as guests in
C
-hexylpyrogallol[4]arene capsules to relay information about the chemical environment on the interior of the assemblies. Spectroscopic and single-crystal x-ray diffraction studies show that, in both solution and the solid state, the host can encapsulate two PBA guests and keep them well separated through specific interactions with the capsule walls.
Electron Plasma Oscillations Upstream of the Solar Wind Termination Shock
Authors: Gurnett D. A. , Kurth W. S.
Published: September 2005

Electron plasma oscillations have been detected upstream of the solar wind termination shock by the plasma wave instrument on the Voyager 1 spacecraft. These waves were first observed on 11 February 2004, at a heliocentric radial distance of 91.0 astronomical units, and continued sporadically with a gradually increasing occurrence rate for nearly a year. The last event occurred on 15 December 2004, at 94.1 astronomical units, just before the spacecraft crossed the termination shock. Since then, no further electron plasma oscillations have been observed, consistent with the spacecraft having crossed the termination shock into the heliosheath.
Crossing the Termination Shock into the Heliosheath: Magnetic Fields
Authors: Burlaga L. F. , Ness N. F. , Acuña M. H. , Lepping R. P. , Connerney J. E. P. , Stone E. C. , McDonald F. B.
Published: September 2005

Magnetic fields measured by Voyager 1 show that the spacecraft crossed or was crossed by the termination shock on about 16 December 2004 at 94.0 astronomical units. An estimate of the compression ratio of the magnetic field strength
B
(± standard error of the mean) across the shock is
B
2
/
B
1
= 3.05 ± 0.04, but ratios in the range from 2 to 4 are admissible. The average
B
in the heliosheath from day 1 through day 110 of 2005 was 0.136 ± 0.035 nanoteslas, ∼4.2 times that predicted by Parker's model for
B
. The magnetic field in the heliosheath from day 361 of 2004 through day 110 of 2005 was pointing away from the Sun along the Parker spiral. The probability distribution of hourly averages of
B
in the heliosheath is a Gaussian distribution. The cosmic ray intensity increased when
B
was relatively large in the heliosheath.
Voyager 1 Explores the Termination Shock Region and the Heliosheath Beyond
Authors: Stone E. C. , Cummings A. C. , McDonald F. B. , Heikkila B. C. , Lal N. , Webber W. R.
Published: September 2005

Voyager 1 crossed the termination shock of the supersonic flow of the solar wind on 16 December 2004 at a distance of 94.01 astronomical units from the Sun, becoming the first spacecraft to begin exploring the heliosheath, the outermost layer of the heliosphere. The shock is a steady source of low-energy protons with an energy spectrum ∼
E
–1.41 ± 0.15
from 0.5 to ∼3.5 megaelectron volts, consistent with a weak termination shock having a solar wind velocity jump ratio

\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(r=2.6_{-0.2}^{+0.4}\) \end{document}

. However, in contradiction to many predictions, the intensity of anomalous cosmic ray (ACR) helium did not peak at the shock, indicating that the ACR source is not in the shock region local to Voyager 1. The intensities of ∼10–megaelectron volt electrons, ACRs, and galactic cosmic rays have steadily increased since late 2004 as the effects of solar modulation have decreased.
Xanthorhodopsin: A Proton Pump with a Light-Harvesting Carotenoid Antenna
Authors: Balashov Sergei P. , Imasheva Eleonora S. , Boichenko Vladimir A. , Antón Josefa , Wang Jennifer M. , Lanyi Janos K.
Published: September 2005

Energy transfer from light-harvesting carotenoids to chlorophyll is common in photosynthesis, but such antenna pigments have not been observed in retinal-based ion pumps and photoreceptors. Here we describe xanthorhodopsin, a proton-pumping retinal protein/carotenoid complex in the eubacterium
Salinibacter ruber
. The wavelength dependence of the rate of pumping and difference absorption spectra measured under a variety of conditions indicate that this protein contains two chromophores, retinal and the carotenoid salinixanthin, in a molar ratio of about 1:1. The two chromophores interact strongly, and light energy absorbed by the carotenoid is transferred to the retinal with a quantum efficiency of ∼40%. The antenna carotenoid extends the wavelength range of the collection of light for uphill transmembrane proton transport.
Mothers Driving Cycles
Authors: Wagner Günter
Published: September 2005

Ecological Orbits
. How Planets Move and Populations Grow.
By Lev Ginzburg and Mark Colyvan
. Oxford University Press, New York, 2004. 182 pp. $29.95, £17.99. ISBN 0-9-516816-X.

The authors offer a short, metaphor-rich argument for the importance of the inertial behavior of biological populations.
CANNIBALISM, FOOD LIMITATION, INTRASPECIFIC COMPETITION, AND THE REGULATION OF SPIDER POPULATIONS
Authors: Wise David H.
Published: September 2005

▪ Abstract  Cannibalism among generalist predators has implications for the dynamics of terrestrial food webs. Spiders are common, ubiquitous arthropod generalist predators in most natural and managed terrestrial ecosystems. Thus, the relationship of spider cannibalism to food limitation, competition, and population regulation has direct bearing on basic ecological theory and applications such as biological control. This review first briefly treats the different types of spider cannibalism and then focuses in more depth on evidence relating cannibalism to population dynamics and food web interactions to address the following questions: Is cannibalism in spiders a foraging strategy that helps to overcome the effects of a limited supply of calories and/or nutrients? Does cannibalism in spiders reduce competition for prey? Is cannibalism a significant density-dependent factor in spider population dynamics? Does cannibalism dampen spider-initiated trophic cascades?
INSECT VECTORS OF PHYTOPLASMAS
Authors: Weintraub Phyllis G. , Beanland LeAnn
Published: September 2005

▪ Abstract  Plant diseases caused by, or associated with, phytoplasmas occur in hundreds of commercial and native plants, causing minor to extensive damage. Insect vectors, primarily leafhoppers, planthoppers, and psyllids, have been identified for relatively few phytoplasma diseases, limiting the capacity of managers to make informed decisions to protect crops and endangered indigenous plants. In the past two decades our knowledge of insect vector–phytoplasma interactions has increased dramatically, allowing researchers to make more accurate predictions about the nature and epidemiology of phytoplasma diseases. These better-characterized systems also may provide clues to the identity of insect vectors of other phytoplasma-associated diseases. We review the literature addressing the ecology of insect vectors, phytoplasma-insect ecological and molecular interactions, vector movement and dispersal, and possible management strategies with an emphasis on research from the past 20 years.
Quantification of hormone-induced atrophy of large myotubes from C2C12 and L6 cells: atrophy-inducible and atrophy-resistant C2C12 myotubes
Authors: Sultan Karim R. , Henkel Birgit , Terlou Maarten , Haagsman Henk P.
Published: September 2005

Myofiber atrophy is the final outcome of muscle wasting induced by catabolic factors such as glucocorticoids and thyroid hormones. We set up an in vitro system to define the catabolic reaction based on myotube atrophy. Both mouse C2C12 and rat L6 cells were used. C2C12 myotube formation was improved by replacing horse serum with the serum substitute Ultroser G. A new method was developed to quantify size changes of large (0.5–1 mm) myotubes only, excluding remaining myoblasts and small myotubes. Dexamethasone reduced myotube size by 30% in L6 but not in C2C12 myotubes. Expression of the glucocorticoid receptor was twofold higher in L6 myotubes than in C2C12 myotubes. In both cell lines, 3,3′,5-triiodo-l-thyronine (T3) did not induce a significant size reduction. Expression of the major T3 receptor (T3Rβ1) was higher in L6 myotubes. We investigated whether the changes in myotube size are related to changes in atrogin-1 expression, as this enzyme is thought to be a key factor in the initiation of muscle atrophy. Dexamethasone induced a twofold increase of atrogin-1 mRNA; again, only L6 myotubes were susceptible. Interestingly, atrogin-1 expression in Ultroser G-fused C2C12 myotubes was lower than that in horse serum-fused myotubes. Furthermore, dexamethasone treatment increased atrogin-1 expression only in horse serum-fused myotubes but not in Ultroser G-fused myotubes. Ultroser G-induced fusion may result in atrophy-resistant C2C12 myotubes. Therefore, C2C12 myotubes offer an ideal system in which to study skeletal muscle atrophy because, depending on differentiation conditions, C2C12 cells produce atrophy-inducible and atrophy-resistant myotubes.
Activation of ETB receptors increases superoxide levels in sympathetic ganglia in vivo
Authors: Lau Yanny E. , Galligan James J. , Kreulen David L. , Fink Gregory D.
Published: September 2005

Dai and colleagues (Dai X, Galligan JJ, Watts SW, Fink GD, and Kreulen DL. Hypertension 43: 1048–1054, 2004) found that endothelin (ET) stimulated O2− production in sympathetic ganglion neurons in vitro by activating ETB receptors. The objective of the present study was to determine whether activation of ETB receptors in vivo elevates O2− levels in sympathetic ganglia. Because ETB receptor activation increases blood pressure, we also sought to determine whether alteration in O2− levels was a direct effect of ETB receptor activation on sympathetic ganglia or an indirect consequence of hypertension. Male Sprague-Dawley rats received intravenous infusions of either the specific ETB receptor agonist sarafotoxin 6c (S6c; 5 pmol·kg−1·min−1) or isotonic saline at 0.01 ml/min (control) for 120 min. To measure O2− levels, we removed the inferior mesenteric ganglion immediately after infusion and stained it with dihydroethidine (DHE). Mean arterial pressure increased 26.6 ± 1.7 mmHg in the S6c-treated rats and 3.65 ± 6 mmHg in control rats. Measurements of average pixel intensity revealed that the DHE fluorescence in ganglionic neurons and surrounding glial cells were 96.7% and 160% greater in S6c-treated than in control rats, respectively. To evaluate the effect of elevated blood pressure on O2− production, a separate group of rats received phenylephrine (PE; 10 μg·kg−1·min−1 iv) for 2 h. MAP increased 31 ± 1.2 mmHg in PE-infused rats. The DHE fluorescence intensity in ganglia of PE-infused rats was significantly greater than that of control rats, 137.7% in neurons and 104.6% in glia but significantly lower than in ganglia from S6c rats. We conclude that ETB receptor activation in vivo significantly enhances O2− levels in sympathetic ganglia, due to both pressor effects and direct stimulation of ETB receptors in ganglion cells.
Differences in finger skin contact cooling response between an arterial occlusion and a vasodilated condition
Authors: Jay Ollie , Havenith George
Published: September 2005

To assess the presence and magnitude of the effect of skin blood flow on finger skin cooling on contact with cold objects against the background of circulatory disorder risks in occupational exposures, this study investigates the effect of zero vs. close-to-maximal hand blood flow on short-term (≤180 s) skin contact cooling response at a contact pressure that allows capillary perfusion of the distal pulp of the fingertip. Six male volunteers touched a block of aluminium with a finger contact force of 0.5 N at a temperature of −2°C under a vasodilated and an occluded condition. Before both conditions, participants were required to exercise in a hot room for ≥30 min for cutaneous vasodilation to occur (increase in rectal temperature of 1°C). Under the vasodilated condition, forearm blood flow rate rose as high as 16.8 ml·100 ml−1·min−1. Under the occluded condition, the arm was exsanguinated, after which a blood pressure cuff was secured on the wrist inducing arterial occlusion. Contact temperature of the finger pad during the subsequent cold contact exposure was measured. No significant difference was found between the starting skin temperatures for the two blood flow conditions, but a distinct difference in shape of the contact cooling curve was apparent between the two blood flow conditions, with Newtonian cooling observed under the occluded condition, whereas a rewarming of the finger skin toward the end of the exposure occurred for the vasodilated condition. Blood flow was found to significantly increase contact temperature from 40 s onward ( P < 0.01). It is concluded that, at a finger contact force compatible with capillary perfusion of the finger pad (∼0.5 N), circulating blood provides a heat input source that significantly affects finger skin contact cooling during a vasodilated state.
A Phase I and Pharmacokinetic Study of Exisulind and Docetaxel in Patients with Advanced Solid Tumors
Authors: Witta Samir E. , Gustafson Daniel L. , Pierson A. Scott , Menter Alexander , Holden Scott N. , Basche Michele , Persky Martha , O’Bryant Cindy L. , Zeng Chan , Baron Anna , Long Michael E. , Gibbs Amy , Kelly Karen , Bunn Paul A. , Chan Daniel C. , Pallansch Patrick , Eckhardt S. Gail
Published: September 2005

Purpose: Exisulind (sulindac sulfone, FGN-1, Aptosyn) is a sulindac metabolite that induces apoptosis via inhibition of cyclic GMP-phosphodiesterase. This agent demonstrated tumor growth inhibition in rodent models of colon, breast, prostate, and lung carcinogenesis. In an orthotopic model of human non–small-cell lung cancer, the combination of exisulind and docetaxel prolonged survival in athymic nude rats, forming the basis of this phase I combination study.

Experimental Design: This study evaluated the toxicity and pharmacokinetics of combining exisulind (150–250 mg) given orally twice daily and docetaxel (30–36 mg/m2) administered intravenously on days 1, 8, and 15 of a 4-week cycle.

Results: Twenty patients with a range of advanced solid tumors (median age, 59 years; age range, 35–77 years; median performance status, 1) received a total of 70 courses. Observed adverse events were mild to moderate, and there was no dose-limiting toxicity at any level. Grade 3 gastrointestinal toxicities were present in 10 of the 70 cycles (10%) and included nausea, vomiting, dyspepsia, and elevated alkaline phosphatase. Neutropenia was present in four cycles in patients treated with a docetaxel dose of 36 mg/m2. Pharmacokinetic analysis did not demonstrate a clear effect of exisulind on docetaxel pharmacokinetics and vice versa. Relationships were evident between the plasma concentration of exisulind and the development of grade 2 or greater toxicities. One third of patients maintained stable disease for 3 to 12 cycles, but no objective responses were observed.

Conclusions: The combination of docetaxel (36 mg/m2, weekly) and exisulind (500 mg/d) was reasonably well tolerated, and it is undergoing phase II testing in patients with non–small-cell lung cancer.
Induction of Apoptosis by Flavopiridol in Human Neuroblastoma Cells Is Enhanced under Hypoxia and Associated With
N-myc
Proto-oncogene Down-Regulation
Authors: Puppo Maura , Pastorino Sandra , Melillo Giovanni , Pezzolo Annalisa , Varesio Luigi , Bosco Maria Carla
Published: September 2005

Purpose: Neuroblastoma is the most common extracranial solid tumor of children that arises from the sympathetic nervous system. Survival rates for neuroblastoma patients is low despite intensive therapeutic intervention, and the identification of new effective drugs remains a primary goal. The cyclin-dependent kinase inhibitor, flavopiridol, has demonstrated growth-inhibitory and cytotoxic activity against various tumor types. Our aim was to investigate flavopiridol effects on advanced-stage, N-myc proto-oncogene (MYCN)-amplified human neuroblastomas and the modulation of its activity by hypoxia, a critical determinant of tumor progression and a major challenge of therapy.

Experimental Design: Cell viability was monitored by 3-(4,5 dimethyl-2 thiazolyl)-2,5 diphenyl-2H tetrazolium bromide (MTT) and trypan blue dye exclusion assays; DNA synthesis was assessed with the bromodeoxyuridine pulse-labeling technique; apoptosis was studied by Giemsa staining, DNA fragmentation, terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling reaction, flow cytometric determination of hypodiploid DNA content, and evaluation of caspase activity and cytochrome c (CytC) release; MYCN expression was determined by Northern and Western blotting.

Results: Flavopiridol caused dose- and time-dependent decreases in neuroblastoma viability by inducing apoptosis, as confirmed by morphologic and biochemical criteria. Cell death was preceded by DNA synthesis inhibition and G1-G2 arrest, reversed by the pancaspase inhibitor, zVAD-fmk, and associated with caspase-3 and -2 activation and CytC increase. Moreover, flavopiridol strongly down-regulated MYCN mRNA and protein expression. Exposure to hypoxia enhanced both the extent of apoptosis and flavopiridol effects on CytC, caspase 3, and MYCN.

Conclusions: These results indicate that flavopiridol has growth-inhibitory and apoptotic activity against advanced-stage neuroblastomas in vitro and is worthy of further investigation for the treatment of this disease.
Allogeneic Hematopoietic Cell Transplantation for Metastatic Renal Cell Carcinoma after Nonmyeloablative Conditioning
Authors: Tykodi Scott S. , Warren Edus H. , Thompson John A. , Riddell Stanley R. , Childs Richard W. , Otterud Brith E. , Leppert Mark F. , Storb Rainer , Sandmaier Brenda M.
Published: September 2005

Purpose: This phase I trial assessed the safety, efficacy, and immunologic responses to minor histocompatibility antigens following nonmyeloablative allogeneic hematopoietic cell transplantation as treatment for metastatic renal cell carcinoma.

Experimental Design: Eight patients received conditioning with fludarabine and low-dose total body irradiation followed by hematopoietic cell transplantation from an HLA-matched sibling donor. Cyclosporine and mycophenolate mofetil were administered as posttransplant immunosuppression. Patients were monitored for donor engraftment of myeloid and lymphoid cells, for clinical response by serial imaging, and for immunologic response by in vitro isolation of donor-derived CD8+ CTLs recognizing recipient minor histocompatibility (H) antigens.

Results: All patients achieved initial mixed hematopoietic chimerism with two patients rejecting their graft and recovering host hematopoiesis. Four patients developed acute, grade 2 to 3, graft-versus-host disease and four patients developed extensive chronic graft-versus-host disease. Five patients had progressive disease, two patients had stable disease, and one patient experienced a partial response after receiving donor lymphocyte infusions and IFN-α. CD8+ CTL clones recognizing minor H antigens were isolated from five patients studied. Clones from three patients with a partial response or stable disease recognized antigens expressed on renal cell carcinoma tumor cells.

Conclusions: Treatment of metastatic renal cell carcinoma with allogeneic hematopoietic cell transplantation after nonmyeloablative conditioning with fludarabine/total body irradiation is feasible and may induce tumor regression or stabilization in some patients. CD8+ CTL-recognizing minor H antigens on tumor cells can be isolated posttransplant and could contribute to the graft-versus-tumor effect. Such antigens may represent therapeutic targets for posttransplant vaccination or adoptive T-cell therapy to augment the antitumor effects of allogeneic hematopoietic cell transplantation.
Expression and Functional Role of CCR9 in Prostate Cancer Cell Migration and Invasion
Authors: Singh Shailesh , Singh Udai P. , Stiles Jonathan K. , Grizzle William E. , Lillard James W.
Published: September 2005

Purpose: Metastasis is responsible for most cancer-related deaths; hence, therapies designed to minimize metastasis are greatly needed. The precise cellular and molecular mechanisms used by cancer cells for metastasis are not fully understood; however, the metastatic spread of neoplastic cells is probably related to the ability of these cells to migrate, invade, home, and survive locally. The migration of tumor cells shares many similarities with leukocyte trafficking, which is regulated by chemokine receptor–ligand interactions. The current study evaluates the molecular mechanisms of CCL25 and CCR9 in prostate cancer cell migration and invasion.

Experimental Design: In the current study, real-time quantitative polymerase chain reaction, flow cytometry analysis, and in vitro migration as well as invasion chamber analysis (with and without antibody-mediated inhibition) were used to ascertain the biological and functional significance of CCR9 expression by normal prostatic epithelial cells (PrEC) or prostate cancer cell lines (LNCaP-10995 and PC3).

Results: We report that functional CCR9 is highly expressed by LNCaP cells and modestly, yet significantly, expressed by PC3 cells when compared with PrEC cells. Neutralization of CCL25–CCR9 interactions impaired the migration and invasion potential of the LNCaP and PC3 cell lines. CCL25 differentially modulated the expression of collagenase-1 or matrix metalloproteinase (MMP)-1, collagenase-3 (MMP-13), stromalysin-2 (MMP-10), stromalysin-3 (MMP-11), and gelatinase-A (MMP-2), but not MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, or MMP-14 in prostate cancer cells.

Conclusions: These studies suggest that the expression and activation of CCR9 affect cancer cell migration, invasion, and MMP expression, which together may affect prostate cancer metastasis.
A Pilot Study to Establish a Clinical Model to Perform Phase II Studies of Breast Cancer Chemopreventive Agents in Women at High Risk with Biomarkers as Surrogate Endpoints for Activity
Authors: Stearns Vered , Gallagher Ann , Kleer Celina G. , Singh Baljit , Freedman Matthew , Haddad Bassem R. , Isaacs Claudine , Warren Robert , Brown Martha , Cullen Jennifer , Trock Bruce , Hayes Daniel F.
Published: September 2005

Purpose: Use of surrogate end point biomarkers in phase II trials may help select agents that appear to have activity and might be evaluated in future phase III definitive trials of breast cancer prevention. We performed a pilot clinical trial to establish the logistics for a clinical model to perform phase II studies of breast cancer chemopreventive agents in women at high risk with novel imaging techniques and candidate surrogate end point biomarkers for activity. We chose tamoxifen to establish proof of principal with a known effective agent.

Experimental Design: Women at a high risk of developing a new breast cancer and for whom tamoxifen was recommended were eligible. The women underwent baseline and 3 and 6 months mammogram and magnetic resonance imaging (MRI) of one breast to identify areas of water-like intensity (epithelial) and to determine the changes over time and MRI-directed core breast biopsies of these areas for surrogate end point biomarkers analysis.

Results: From August 1999 to March 2001, 26 women underwent baseline imaging and core biopsies. Sixteen women took tamoxifen and 10 chose not to. Overall, 79% of the samples contained glandular tissue evaluable for histology, but only 66% of the samples were evaluable for marker analysis. Only 12 patients had specimens with glandular tissue sufficient for marker analysis both at baseline and in at least one follow-up. Because of the small number of women with matched samples, marker analysis was not informative.

Conclusions: This study shows the feasibility of obtaining serial core breast biopsies from women at a high risk of developing a new breast cancer. Patient participation in this model is satisfactory, and such a model may provide indication of drug activity. MRI-directed biopsy did not provide a high yield of evaluable samples, and additional work on adequate collection of epithelial tissue for surrogate end point biomarker analysis is thus necessary.
Increased Fas Expression Reduces the Metastatic Potential of Human Osteosarcoma Cells
Authors: Lafleur Elizabeth A. , Koshkina Nadezhda V. , Stewart John , Jia Shu-Fang , Worth Laura L. , Duan Xiaoping , Kleinerman Eugenie S.
Published: September 2005

Purpose: The process of metastasis requires the single tumor cell that seeds the metastatic clone to complete a complex series of steps. Identifying factors responsible for these steps is essential in developing and improving targeted therapy for metastasis. Resistance to receptor-mediated cell death, such as the Fas/Fas ligand pathway, is one mechanism commonly exploited by metastatic cell populations.

Experimental Design and Results: LM7, a subline of the SAOS human osteosarcoma cell line with low Fas expression, was selected for its high metastatic potential in an experimental nude mouse model. When transfected with the full-length Fas gene (LM7-Fas), these cells expressed higher levels of Fas than the parental LM7 cells or LM7-neo control-transfected cells. These cells were also more sensitive to Fas-induced cell death than controls. When injected intravenously into nude mice, the LM7-Fas cell line produced a significantly lower incidence of tumor nodules than control cell lines. Lung weight and tumor nodule size were also decreased in those mice injected with LM7-Fas. Levels of Fas were quantified in osteosarcoma lung nodules from 17 patients. Eight samples were Fas negative, whereas the remaining 9 were only weakly positive compared with normal human liver (positive control).

Conclusions: Our results demonstrate that altering Fas expression can impact the metastatic potential of osteosarcoma cells. We conclude that the increase of Fas on the surface of the LM7 osteosarcoma cells increased their sensitivity to Fas-induced cell death in the microenvironment of the lung, where Fas ligand is constitutively expressed. Thus, loss of Fas expression is one mechanism by which osteosarcoma cells may evade host resistance mechanisms in the lung, increasing metastatic potential. Fas may therefore be a new therapeutic target for osteosarcoma.
Matrix Metalloproteinase/Tissue Inhibitors of Matrix Metalloproteinase Phenotype Identifies Poor Prognosis Colorectal Cancers
Authors: Curran Stephanie , Dundas Sinclair R. , Buxton Jenny , Leeman Matthew F. , Ramsay Robin , Murray Graeme I.
Published: September 2005

Purpose: The matrix metalloproteinases (MMPs) are a family of proteolytic enzymes involved in tumor invasion; several individual members of which have been implicated in tumor prognosis. These enzymes and their physiologic inhibitors, the tissue inhibitors of matrix metalloproteinases (TIMPs), act in a coordinated manner to form an integrated system. Therefore, to understand their role in tumor invasion, it is necessary to evaluate them collectively.

Experimental Design: In this study all of the major members of the matrix metalloproteinase (MMP-1, MMP-2, MMP-3,MMP-7, MMP-9, MMP-13, MT1-MMP and MT2-MMP)/tissue inhibitor of matrix metalloproteinase (TIMP-1, TIMP-2, and TIMP-3) system have been investigated by immunohistochemistry in a series (n = 90) of stage III (Dukes’ C) colorectal cancers. An immunohistochemical score based on the intensity of immunoreactivity and proportion of immunoreactive cells was established for each MMP and TIMP.

Results: The MMP/TIMP profile defined by hierarchical cluster analysis of the immunohistochemical score identifies a distinct group of colorectal cancers with poor prognosis (log-rank test, 12.22, P = 0.0005). The median survival time of patients in this survival group was 18 months compared with a median survival of 49 months in the “good” survival group. Multivariate analysis showed that this profile was independently the most significant prognostic factor (P = 0.001).

Conclusions: This study has identified that the MMP/TIMP profile is an independent indicator of poor prognosis in colorectal cancer.
Low Levels of Insulin-Like Growth Factor Type 1 Receptor Expression at Cancer Cell Membrane Predict Liver Metastasis in Dukes’ C Human Colorectal Cancers
Authors: Nakamura Michio , Miyamoto Shin’ichi , Maeda Hiroyuki , Zhang Shi-chuan , Sangai Takafumi , Ishii Genichiro , Hasebe Takahiro , Endoh Yasushi , Saito Norio , Asaka Masahiro , Ochiai Atsushi
Published: September 2005

Purpose: The aim of this study was to evaluate the prognostic significance of insulin-like growth factor type 1 receptor (IGF-1R) expression in Dukes’ C human colorectal cancers (CRCs).

Experimental Design: Immunohistochemical staining for IGF-1R was done on formalin-fixed, paraffin-embedded specimens from 161 patients with curatively resected Dukes’ C CRC and at least 5-year follow-up periods. We investigated the association between the levels of IGF-1R expression and the clinicopathologic parameters. To evaluate the accurate prognostic value of IGF-1R expression, we investigated two patterns of recurrence-free survival (RFS) according to the mode of recurrence, the hepatic-RFS (H-RFS), and the nonhepatic-RFS (nH-RFS). The influence of the pattern of IGF-1R immunostaining (membranous or cytoplasmic) on RFS was also estimated.

Results: High (diffuse staining) and low (focal staining) levels of IGF-1R expression were found in 45 (28%) and 116 (72%) specimens, respectively. The recurrence rate was significantly higher in the latter group (49 of 116) than the former group (9 of 45; P = 0.01). H-RFS was significantly longer for the former group than the latter group (P = 0.021), whereas no difference was found in nH-RFS between the two groups (P = 0.121). In multivariate analysis, the level of IGF-1R expression was an independent factor for H-RFS (P = 0.015) as were the depth of invasion and lymph vessel invasion (P = 0.006 and 0.022, respectively). Using a combination of the level of IGF-1R expression and these two factors, the prognostic value was further increased. When IGF-1R staining patterns (membranous or cytoplasmic) were compared, membrane staining of IGF-1R possessed prognostic significance.

Conclusions: In Dukes’ C CRC, focal membrane expression of IGF-1R in the primary tumor can predict a high risk of recurrence, especially liver metastasis. Understanding the mechanisms involved could lead to new therapeutic approaches for advanced CRC.
In vitro
Effects of the BH3 Mimetic, (−)-Gossypol, on Head and Neck Squamous Cell Carcinoma Cells
Authors: Oliver Christopher L. , Bauer Joshua A. , Wolter Keith G. , Ubell Mathew L. , Narayan Ajita , O’Connell Kathleen M. , Fisher Susan G. , Wang Shaomeng , Wu Xihan , Ji Min , Carey Thomas E. , Bradford Carol R.
Published: September 2005

Purpose: Bcl-xL overexpression is common in head and neck squamous cell carcinomas (HNSCC) and correlates with resistance to chemotherapy. Thus, a nonpeptidic, cell-permeable small molecule that mimics the BH3 domain of proapoptotic proteins may inhibit Bcl-xL function and have therapeutic potential for HNSCC by overcoming drug-resistance. (−)-Gossypol, the levorotatory isomer of a natural product isolated from cottonseeds and roots, was recently discovered to bind to the BH3 binding groove of Bcl-xL and Bcl-2.

Experimental Design: We investigated the in vitro effects of (−)-gossypol on HNSCC cell lines as well as on fibroblast and keratinocyte cultures by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell survival assays and assessed the results with respect to Bcl-2 family protein expression.

Results: We observed dose-dependent growth inhibition of 10 HNSCC cell lines at biologically achievable doses (2.5–10 μmol/L). (−)-Gossypol doses required to inhibit the growth of human fibroblast cell lines by 50% were 2- to 10-fold higher than for HNSCC cell lines. To inhibit human oral keratinocyte growth by 50%, (−)-gossypol concentrations were 2-to 3-fold higher than for HNSCC cell lines.

Conclusions: There is a direct correlation between Bcl-xL-to-Bcl-xS ratios and sensitivity to (−)-gossypol. This agent induced apoptosis in a much higher proportion of cells with wild-type p53. Importantly, cell lines resistant to cisplatin were very sensitive to (−)-gossypol. These results demonstrate that (−)-gossypol has potent antitumor activity in HNSCC in vitro. This agent may be developed as a novel therapeutic agent for HNSCC, either alone or in combination with existing chemotherapeutic agents.
Prognostic Value of
ERM
Gene Expression in Human Primary Breast Cancers
Authors: Chotteau-Lelièvre Anne , Révillion Françoise , Lhotellier Valérie , Hornez Louis , Desbiens Xavier , Cabaret Véronique , de Launoit Yvan , Peyrat Jean-Philippe
Published: September 2005

We measured the expression of ERM gene, a nuclear transcription factor belonging to the ets family, in a series of 364 unselected primary breast cancers from patients who underwent locoregional surgery in the Centre Oscar Lambret between May 1989 and December 1991. The expression of ERM was quantified with a real-time one-step reverse transcription-PCR assay based on the 5′-nuclease activity of the TaqDNA polymerase and with an Abi Prism 7700 Sequence Detector System (Applied Biosystems, Courtaboeuf, France). ERM was positively correlated (Spearman test) to epidermal growth factor receptor (EGFR; P < 0.001, r = 0.296) and to histoprognostic grading (P = 0.044, r = 0.112), whereas it was negatively correlated to estradiol receptors (P = 0.019, r = -0.124), HER3 (c-erbB-3; P = 0.01, r = −0.135), and HER4 (c-erbB-4; P = 0.003, r = −0.154). Using the χ2 test, a positive relationship was found between the expression of ERM and EGFR (χ2 = 7.795, P = 0.007). In overall survival studies, Cox univariate analyses demonstrated a prognostic value of ERM (P = 0.006; risk ratio, 2.95) besides the classical prognostic factors histoprognostic grading, node involvement, tumor size, estradiol receptors, progesterone receptors, EGFR, HER3, and HER4. In multivariate analyses, ERM preserved its prognostic value (P = 0.004; risk ratio, 3.779) together with histoprognostic grading, tumor size, estradiol receptors, and progesterone receptors. In relapse-free survival studies, univariate analyses demonstrated that histoprognostic grading, node involvement, tumor size, and HER4 were prognostic factors. These parameters, except histoprognostic grading, retained their prognostic value in multivariate analyses. This study demonstrates for the first time that ERM gene expression is an independent adverse prognostic factor for overall survival in breast cancer patients.
Inhibition of Src Tyrosine Kinase as Treatment for Human Pancreatic Cancer Growing Orthotopically in Nude Mice
Authors: Yezhelyev Maksim V. , Koehl Gudrun , Guba Markus , Brabletz Thomas , Jauch Karl-Walter , Ryan Anderson , Barge Alan , Green Tim , Fennell Michael , Bruns Christiane J.
Published: September 2005

Purpose: The Src family comprises a family of nonreceptor intracellular tyrosine kinases that mediate a variety of cellular pathways. Src kinases are overexpressed in a variety of human tumors, including cancer of the colon, breast, and pancreas, and they are an integral part of tumor cell signaling pathways associated with migration, proliferation, adhesion, and angiogenesis.

Experimental Design: We investigated whether the blockade of Src kinase by daily oral administration of the novel Src tyrosine kinase inhibitor AZM475271 [kindly provided by AstraZeneca (Macclesfield, United Kingdom)], alone or in combination with intraperitoneal gemcitabine, can inhibit growth and metastasis of orthotopically implanted human pancreatic carcinoma cells in nude mice.

Results: Treatment with AZM475271 alone reduced the primary pancreatic tumor volume by approximately 40%, whereas AZM475271 plus gemcitabine reduced tumor volume by 90%. Furthermore, treatment with AZM475271 and gemcitabine significantly reduced metastasis: none of eight animals who received the combination treatment had lymph node or liver metastases, compared with five of five and three of five animals, respectively, in the control group (P = 0.001). Src inhibition by AZM475271 (alone or with gemcitabine) was associated with significantly reduced tumor cell proliferation, decreased tumor microvessel density, and increased apoptosis in vivo. Moreover, these effects were all significantly increased when gemcitabine was combined with AZM475271 compared with gemcitabine alone.

Conclusions: Src inhibition by AZM475271, either alone or in combination with gemcitabine, demonstrated significant antitumor and antimetastatic activity in an orthotopic nude mouse model for human pancreatic cancer. The combination of AZM475271 with gemcitabine sensitized tumor cells to the cytotoxic effect of gemcitabine.
Delivery of a Liposomal
c-raf-1
Antisense Oligonucleotide by Weekly Bolus Dosing in Patients with Advanced Solid Tumors
Authors: Rudin Charles M. , Marshall John L. , Huang Chao Hui , Kindler Hedy L. , Zhang Chuanbo , Kumar Deepak , Gokhale Prafulla C. , Steinberg Joyce , Wanaski Steve , Kasid Usha N. , Ratain Mark J.
Published: September 2005

Purpose: Rapid cleavage in vivo and inefficient cellular uptake limit the clinical utility of antisense oligonucleotides (AON). Liposomal formulation may promote better intratumoral AON delivery and inhibit degradation in vivo. We conducted the first clinical evaluation of this concept using a liposomal AON complementary to the c-raf-1 proto-oncogene (LErafAON).

Experimental Design: A dose escalation study was done to determine the maximum tolerated dose and to characterize the toxicities of LErafAON given as weekly intravenous infusion for 8 weeks to adults with advanced solid tumors. Pharmacokinetic analysis and evaluation of c-raf-1 target suppression in peripheral blood mononuclear cells were included.

Results: Twenty-two patients received LErafAON (median 7 infusions; range 1–27) at doses of 1, 2, 4, and 6 mg/kg/week. Across all dose cohorts patients experienced infusion-related hypersensitivity reactions including flushing, dyspnea, hypoxia, rigors, back pain, and hypotension. Prolonged infusion duration and pretreatment with acetaminophen, H1- and H2-antagonists, and corticosteroids reduced the frequency and severity of these reactions. Progressive thrombocytopenia was dose-limiting at 6 mg/kg/week. No objective responses were observed. Two patients treated at the maximum tolerated dose of 4 mg/kg/week had evidence of stable disease, with dosing extended beyond 8 weeks. Pharmacokinetic analysis revealed persistence of detectable circulating rafAON at 24 hours in 7 of 10 patients in the highest 2 dose cohorts. Suppression of c-raf-1 mRNA was noted in two of five patients analyzed.

Conclusions: Dose-independent hypersensitivity reactions and dose-dependent thrombocytopenia limited tolerance of LErafAON. Future clinical evaluation of this approach will depend on modification of the liposome composition.
Species Differences in Troxacitabine Pharmacokinetics and Pharmacodynamics
Authors: Gourdeau Henriette , Leblond Lorraine , Hamelin Bettina , Dong Kelly , Ouellet France , Boudreau Chantal , Custeau Dominique , Richard Annie , Gilbert Marie-Josée , Jolivet Jacques
Published: September 2005

Purpose: Troxacitabine is the first unnatural l-nucleoside analog to show potent preclinical antitumor activity and is currently under clinical investigation. Significant differences in troxacitabine toxicity between mice, rats, monkeys, and humans were observed during preclinical and clinical evaluations. To better understand the different toxicity and efficacy results observed between the human xenograft mouse tumor models used for preclinical assessment and the clinical study results, the pharmacodynamics and pharmacokinetics of troxacitabine were reassessed in murine and human models.

Experimental Design: Clonal and thymidine incorporation assays were used to investigate the in vitro antiproliferative activity of troxacitabine on a selected panel of mouse and human tumor cell lines and normal hemapoietic cells. Analysis of the intracellular metabolites of [14C]troxacitabine was determined in mouse and human T-lymphocytes obtained from peripheral blood. The antitumor efficacy of troxacitabine administered either as single or repeated high-dose bolus administrations or as low-dose continuous infusions was evaluated in the human colon HT-29 xenograft model. We also determined plasma concentrations of troxacitabine using the different administration schedules.

Results: Five to nine hundred-fold lower concentrations of troxacitabine were required to inhibit cell growth in human compared with murine tumor and normal hemapoietic cell lines. Furthermore, the sensitivity of cells of both species to troxacitabine was strongly time dependent, requiring >24 hours exposure for maximum activity. Analysis of the intracellular metabolites of [14C]troxacitabine in T-lymphocytes obtained from peripheral blood revealed subsequently higher levels of mono-, di-, and triphosphates in human compared with mouse. Antitumor efficacy studies revealed that prolonged exposure schedules (up to 6 days) showed equivalent efficacy to repeated high-dose bolus administrations. Five-day continuous infusion of 20 mg/mL troxacitabine via subcutaneous implanted mini-osmotic pump maintained systemic concentrations of 262 ng/mL (1.2 μmol/L) for the duration of administration, which are clinically achievable plasma concentrations, and led to significant antitumor activity [treated versus control (T/C) of 27% and tumor regression during treatment].

Conclusions: These studies support the hypothesis that troxacitabine infusions might be the administration regimen with the greatest likelihood of fully exploiting clinically the potent preclinical antitumor activity of troxacitabine.