bluuebunny/crossref_metadata_2025 huggingface dataset:
Carboniferous granitic plutons from the northern margin of the North China block: implications for a late Palaeozoic active continental margin
Authors: ZHANG SHUAN-HONG , ZHAO YUE , SONG BIAO , YANG ZHEN-YU , HU JIAN-MIN , WU HAI
Published: February 2007

We report four late Palaeozoic zircon sensitive high-resolution ion microprobe (SHRIMP) U–Pb ages for granitic plutons from the Inner Mongolia Palaeo-uplift on the northern margin of the North China block. These cast a new light on the poorly understood tectonic history of the northern margin of the North China block and the Central Asian Orogenic Belt during the late Palaeozoic. The plutons have for a long time been considered to belong to the early Precambrian basement of the North China block. Our new SHRIMP U–Pb zircon dating of four plutons at Longhua, Daguangding, Boluonuo and Hushiha has yielded intrusive ages of 311 ± 2 Ma, 324 ± 6 Ma, 302 ± 4 Ma and 310 ± 5 Ma, respectively. Geochemical data suggest that these granitoids have a calc-alkaline, subduction-related I-type signature, indicating the existence of an Andean-style continental arc along the northern margin of the North China block during the late Palaeozoic. Our results also indicate that the Palaeo-Asian Ocean still existed during latest Carboniferous–earliest Permian time, and that the final collision between the southern Mongolia composite terranes and the North China block occurred later than
c
. 290 Ma. We suggest that the northern margin of the North China block was an active continental margin and the Inner Mongolia Palaeo-uplift is a deeply exhumed mid-crustal ‘root’ of a late Palaeozoic Andean-style continental arc.
A deep geothermal exploration well at Eastgate, Weardale, UK: a novel exploration concept for low-enthalpy resources
Authors: Manning D.A.C. , Younger P.L. , Smith F.W. , Jones J.M. , Dufton D.J. , Diskin S.
Published: February 2007

The first deep geothermal exploration borehole (995 m) to be drilled in the UK for over 20 years was completed at Eastgate (Weardale, Co. Durham) in December 2004. It penetrated 4 m of sandy till (Quaternary), 267.5 m of Lower Carboniferous strata (including the Whin Sill), and 723.5 m of the Weardale Granite (Devonian), with vein mineralization occurring to 913 m. Unlike previous geothermal investigations of UK radiothermal granites that focused on the hot dry rock concept, the Eastgate Borehole was designed to intercept deep fracture-hosted brines associated with the major, geologically ancient, hydrothermal vein systems. Abundant brine (≤46 °C) was encountered within natural fracture networks of very high permeability (transmissivity
c
. 2000 darcy m) within granite. Evidence for the thermal history of the Carboniferous rocks from phytoclast reflectance measurements shows very high values (≥3.3%) indicating maximum temperatures of 130 °C prior to intrusion of the Whin Sill. Geochemical analysis of cuttings samples from the Eastgate Borehole suggests radiothermal heat production rates for unaltered Weardale Granite averaging 4.1 μW m
−3
, with a mean geothermal gradient of 38 °C km
−1
. The Eastgate Borehole has significant exploitation potential for direct heat uses; it demonstrates the potential for seeking hydrothermal vein systems within radiothermal granites as targets for geothermal resources.
Paratropical floral extinction in the Late Palaeocene–Early Eocene
Authors: Harrington Guy J. , Jaramillo Carlos A.
Published: February 2007

The Palaeocene–Eocene Thermal Maximum (PETM) at
c
. 55.8 Ma marks a transient (
c
. 100 ka duration) interval of rapid greenhouse warming that had profound effects on marine and terrestrial biota. Plant communities responded rapidly with major compositional turnover. The long-term effects on tropical vegetation communities that stem from the brief period of global warming are unclear. We present pollen data from the paratropical US Gulf Coast (eastern Mississippi, western Alabama and Georgia), which had background Palaeogene mean annual temperatures of 26–27 °C. Sporomorph data (pollen and spores) demonstrate that taxonomic diversity increases over
c
. 1 Ma in the Late Palaeocene but this trend is replaced, with the first occurrences of taxa that mark the Early Eocene, by a pronounced extinction into the Early Eocene (
c
. 20% of the palynoflora). Taxonomic diversity also decreases by up to 38% in the Early Eocene. The timing of the extinction is not clearly resolved but may be restricted to the earliest part of the Early Eocene. Two richness estimators (Chao 2 and Jackknife 2) both demonstrate that Late Palaeocene samples contain significantly more taxa than those in the Early Eocene. Extinction on the US Gulf Coast proves that ancient tropical ecosystems were highly susceptible to changes in diversity mediated directly or indirectly by environmental change even during equable greenhouse climates in the early Palaeogene.
Tectonic and climatic controls of alluvial-fan size and source-catchment relief
Authors: Dade W.Brian , Verdeyen Meagan E.
Published: February 2007

The geometries of alluvial fans and their upland catchments subject to known rates of basin subsidence
V
and upland precipitation
P
, respectively, are compared with predictions from a quantitative analysis of an idealized landscape. We find that the dimensionless ratio
V
/
P
explains systematic trends in relative fan size and source catchment relief previously reported from environmentally wide-ranging regions worldwide, and contributes to the interpretation of recently reported observations of fan-like phenomena on Mars.
Phosphosilicate Glass Stabilization of MOS Structures
Authors: Kaplan L. H. , Lowe M. E.
Published: February 2007

The flatband voltage and stability of metal‐glass‐oxide‐silicon (MGOS) systems were studied for phosphosilicate glass layers of varying thickness and composition. Thickness from 30 to 200Aå and compositions from 1 to 6 mole per cent (m/o)

P

2

O

5

were used with a total insulator thickness of 500Aå. Electrical properties were measured after contamination (before metallization) of 4 different levels of sodium ranging from approximately 1011 to 1014/cm2. The initial flatband voltage was found to be linear with both sodium contamination and PSG thickness. The

δ

V

FB

shift (due to +10V bias at 200°C for 10 min) is a decreasing linear function of the product of thickness and

P

2

O

5

concentration up to a value of

(

t

PSG

×
M
%
)

sufficient to trap all sodium. At higher PSG levels, the

δ

V

FB

increases. For a desired level of Na protection, the thickness—mole per cent product needed, can be determined by the figures supplied.
Analysis of Porous Electrodes with Sparingly Soluble Reactants
Authors: Dunning John S. , Bennion Douglas N. , Newman John
Published: February 2007

A model is developed for the operation of a porous electrode in which slightly soluble reactants are present. Numerical techniques are used to predict current distribution and total electrode polarization for the case of a uniform porous structure. This technique is extended to the case where nonuniformities in reactant conversion are produced by a nonuniform current distribution within the electrode. In addition, a simulation of electrode behavior on repeated cycling is obtained. The implications of nonuniform reactant conversion and mass transfer limitations for real battery electrodes are discussed. The results of the numerical calculations indicate that diffusion‐limited currents within the porous electrode are possible for certain input parameters. The high polarization at constant current corresponding to a limiting current may be obtained after some time of discharge, but before all of the theoretically available active material is used. In the cycling simulation, significant changes in the relative distribution of reactants and products were observed as a function of depth in the electrode. These changes caused differences in the total electrode polarization from cycle to cycle.
Effects of Carbonate on the Anodic Dissolution and the Passivation of Zinc Electrode in Concentrated Solution of Potassium Hydroxide
Authors: Sato Yuichi , Niki Hirokazu , Takamura Tsutomu
Published: February 2007

The effect of carbonate ions on the anodic behavior of a horizontal zinc anode in concentrated

KOH

solutions has been investigated by measuring the passivation time at constant current. Anodic dissolution of zinc was found to be associated with the diffusion‐controlled zincate ion saturation near the electrode and the passivation time of the electrode, which is defined to be a period until the passivation occurs, was reduced with increasing concentration of carbonate ions at constant concentration of

KOH

. The phenomenon was explained from the linear relationship between tp and 1/η as a result of the increase in viscosity η of the solution.
Ca2+ entry-independent effects of L-type Ca2+ channel modulators on Ca2+ sparks in ventricular myocytes
Authors: Copello Julio A. , Zima Aleksey V. , Diaz-Sylvester Paula L. , Fill Michael , Blatter Lothar A.
Published: February 2007

During the cardiac action potential, Ca2+ entry through dyhidropyridine receptor L-type Ca2+ channels (DHPRs) activates ryanodine receptors (RyRs) Ca2+-release channels, resulting in massive Ca2+ mobilization from the sarcoplasmic reticulum (SR). This global Ca2+ release arises from spatiotemporal summation of many localized elementary Ca2+-release events, Ca2+ sparks. We tested whether DHPRs modulate Ca2+sparks in a Ca2+ entry-independent manner. Negative modulation by DHPR of RyRs via physical interactions is accepted in resting skeletal muscle but remains controversial in the heart. Ca2+ sparks were studied in cat cardiac myocytes permeabilized with saponin or internally perfused via a patch pipette. Bathing and pipette solutions contained low Ca2+ (100 nM). Under these conditions, Ca2+ sparks were detected with a stable frequency of 3–5 sparks·s−1·100 μm−1. The DHPR blockers nifedipine, nimodipine, FS-2, and calciseptine decreased spark frequency, whereas the DHPR agonists Bay-K8644 and FPL-64176 increased it. None of these agents altered the spatiotemporal characteristics of Ca2+ sparks. The DHPR modulators were also without effect on SR Ca2+ load (caffeine-induced Ca2+ transients) or sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) activity (Ca2+ loading rates of isolated SR microsomes) and did not change cardiac RyR channel gating (planar lipid bilayer experiments). In summary, DHPR modulators affected spark frequency in the absence of DHPR-mediated Ca2+ entry. This action could not be attributed to a direct action of DHPR modulators on SERCA or RyRs. Our results suggest that the activity of RyR Ca2+-release units in ventricular myocytes is modulated by Ca2+ entry-independent conformational changes in neighboring DHPRs.
G protein activation inhibits gating charge movement in rat sympathetic neurons
Authors: Hernández-Ochoa Erick O. , García-Ferreiro Rafael E. , García David E.
Published: February 2007

G protein-coupled receptors (GPCRs) control neuronal functions via ion channel modulation. For voltage-gated ion channels, gating charge movement precedes and underlies channel opening. Therefore, we sought to investigate the effects of G protein activation on gating charge movement. Nonlinear capacitive currents were recorded using the whole cell patch-clamp technique in cultured rat sympathetic neurons. Our results show that gating charge movement depends on voltage with average Boltzmann parameters: maximum charge per unit of linear capacitance ( Qmax) = 6.1 ± 0.6 nC/μF, midpoint ( Vh) = −29.2 ± 0.5 mV, and measure of steepness ( k) = 8.4 ± 0.4 mV. Intracellular dialysis with GTPγS produces a nonreversible ∼34% decrease in Qmax, a ∼10 mV shift in Vh, and a ∼63% increase in k with respect to the control. Norepinephrine induces a ∼7 mV shift in Vh and ∼40% increase in k. Overexpression of G protein β1γ4 subunits produces a ∼13% decrease in Qmax, a ∼9 mV shift in Vh, and a ∼28% increase in k. We correlate charge movement modulation with the modulated behavior of voltage-gated channels. Concurrently, G protein activation by transmitters and GTPγS also inhibit both Na+ and N-type Ca2+ channels. These results reveal an inhibition of gating charge movement by G protein activation that parallels the inhibition of both Na+ and N-type Ca2+ currents. We propose that gating charge movement decrement may precede or accompany some forms of GPCR-mediated channel current inhibition or downregulation. This may be a common step in the GPCR-mediated inhibition of distinct populations of voltage-gated ion channels.
Cyclic strain and motion control produce opposite oxidative responses in two human endothelial cell types
Authors: Sung Hak-Joon , Yee Andrew , Eskin Suzanne G. , McIntire Larry V.
Published: February 2007

The phenotype of endothelial cells (ECs) is specific to the vascular bed from which they originate. To examine how mechanical forces alter the phenotype of different ECs, we compared the effects of cyclic strain and motion control on reactive oxygen species (ROS) production and metabolism and cell adhesion molecule expression in human umbilical vein endothelial cells (HUVEC) vs. human aortic endothelial cells (HAEC). HUVEC and HAEC were subjected to cyclic strain (10% or 20%, 1 Hz), to a motion control that simulated fluid agitation over the cells without strain, or to static conditions for 24 h. We measured H2O2 production with dichlorodihydrofluorescein acetate and superoxide with dihydroethidium fluorescence changes; superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) activities spectrophotometrically; and vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1 protein expression with Western blot analyses. HUVEC under cyclic strain showed 1) higher intracellular H2O2 levels, 2) increased SOD, catalase, and GPx activities, and 3) greater VCAM-1 and ICAM-1 protein expression, compared with motion control or static conditions. However, in HAEC, motion control induced higher levels of ROS, enzyme activities associated with ROS defense, and VCAM-1 and ICAM-1 expression than cyclic strain. The opposite responses obtained with these two human EC types may reflect their vessels of origin, in that HAEC are subjected to higher cyclic strain deformations in vivo than HUVEC.
Loss of NF-κB activation in Kupffer cell-depleted mice impairs liver regeneration after partial hepatectomy
Authors: Abshagen Kerstin , Eipel Christian , Kalff Jörg C. , Menger Michael D. , Vollmar Brigitte
Published: February 2007

Kupffer cells (KCs) are located in the liver sinusoids adjacent to hepatocytes and are capable of producing important growth-regulating mediators that exert both stimulatory and inhibitory influences on hepatocyte proliferation by paracrine mechanisms. To elucidate the overall effect of KC depletion on liver regeneration, mice were selectively and long-standing depleted of KCs by liposome-encapsulated dichloromethylene diphosphonate. Using in vivo fluorescence microscopy, immunohistochemistry, Western blot analysis, and NF-κB transcription factor DNA binding activity and cytokine assays, we analyzed livers of KC-depleted and KC-competent mice at days 3, 5, and 8 after partial (i.e., 68%) hepatectomy (PH). Selective KC elimination delayed cell proliferation, as indicated by significantly reduced PCNA and cyclin B1 protein expression in liver tissue at day 3 after PH. This was associated with a lower liver weight at day 8 upon PH. Resection-associated activation of NF-κB with translocation into parenchymal and nonparenchymal cell nuclei was diminished in livers of KC-depleted mice, primarily at day 3 after PH. KC-depleted mice further lacked the resection-induced rise in TNF-α and IL-6 serum concentrations. These findings imply that KCs play a stimulatory role in liver regeneration, mainly by activating NF-κB with influence on the cell cycle and by enhancing expression of the proliferative cytokines TNF-α and IL-6.
High-altitude chronic hypoxia during gestation and after birth modifies cardiovascular responses in newborn sheep
Authors: Herrera Emilio A. , Pulgar Víctor M. , Riquelme Raquel A. , Sanhueza Emilia M. , Reyes Roberto V. , Ebensperger Germán , Parer Julian T. , Valdéz Enrique A. , Giussani Dino A. , Blanco Carlos E. , Hanson Mark A. , Llanos Aníbal J.
Published: February 2007

Perinatal exposure to chronic hypoxia induces sustained pulmonary hypertension and structural and functional changes in both pulmonary and systemic vascular beds. The aim of this study was to analyze consequences of high-altitude chronic hypoxia during gestation and early after birth in pulmonary and femoral vascular responses in newborn sheep. Lowland (LLNB; 580 m) and highland (HLNB; 3,600 m) newborn lambs were cathetherized under general anesthesia and submitted to acute sustained or stepwise hypoxic episodes. Contractile and dilator responses of isolated pulmonary and femoral small arteries were analyzed in a wire myograph. Under basal conditions, HLNB had a higher pulmonary arterial pressure (PAP; 20.2 ± 2.4 vs. 13.6 ± 0.5 mmHg, P < 0.05) and cardiac output (342 ± 23 vs. 279 ± 13 ml·min−1·kg−1, P < 0.05) compared with LLNB. In small pulmonary arteries, HLNB showed greater contractile capacity and higher sensitivity to nitric oxide. In small femoral arteries, HLNB had lower maximal contraction than LLNB with higher maximal response and sensitivity to noradrenaline and phenylephrine. In acute superimposed hypoxia, HLNB reached higher PAP and femoral vascular resistance than LLNB. Graded hypoxia showed that average PAP was always higher in HLNB compared with LLNB at any Po2. Newborn lambs from pregnancies at high altitude have stronger pulmonary vascular responses to acute hypoxia associated with higher arterial contractile status. In addition, systemic vascular response to acute hypoxia is increased in high-altitude newborns, associated with higher arterial adrenergic responses. These responses determined in intrauterine life and early after birth could be adaptive to chronic hypoxia in the Andean altiplano.
In a hypergravity environment neonatal survival is adversely affected by alterations in dam tissue metabolism rather than reduced food intake
Authors: Lintault Laura M. , Zakrzewska Elzbieta I. , Maple Rhonda L. , Baer Lisa A. , Casey Theresa M. , Ronca April E. , Wade Charles E. , Plaut Karen
Published: February 2007

Exposure of rat dams to hypergravity during pregnancy is associated with increased pup mortality, reduced food intake, and decreased rates of glucose oxidation and lipogenesis in mammary tissue. We hypothesized that increased pup mortality is due to changes in maternal metabolism and not to reduced food intake of dams. Effects of hypergravity on rate of glucose oxidation and lipogenesis in mammary, liver, and adipose tissue were measured in rat dams centrifuged at 2.0 G [hypergravity (HG)], kept at 1.0 G (control), or fed to match the intake of HG rats (pair fed) from gestation day 11 (G11) until G21 or postpartum day 3 (P3). Body weight, percent body fat, metabolizable energy, and nitrogen balance were significantly less in HG dams compared with controls ( P < 0.05); however, these factors were not different between HG and pair-fed dams. By P3, 100% of control and pair-fed pups survived, while only 49% of HG pups survived. At G21, rates of glucose oxidation and lipogenesis in mammary and adipose tissue were less in HG than in control and pair-fed dams ( P < 0.1 and P < 0.05). In liver, at G21, the rate of lipogenesis was greater in HG than control and pair-fed dams ( P < 0.01); at P3, lipogenesis was greater in control than HG and pair-fed dams ( P < 0.05). Gene expression of ATP citrate lyase, acetyl-CoA carboxylase, and fatty acid synthase increased in liver from pregnancy to lactation in control and pair-fed dams but not HG dams. Thus reduced food intake and body mass due to hypergravity exposure cannot explain the dramatic decrease in HG pup survival.
Movements and Muscle Activity Initiated by Brain Locomotor Areas in Semi-Intact Preparations From Larval Lamprey
Authors: Jackson Adam W. , Pino Felicity A. , Wiebe Erica D. , McClellan Andrew D.
Published: February 2007

In in vitro brain/spinal cord preparations from larval lamprey, locomotor-like ventral root burst activity can be initiated by pharmacological (i.e., “chemical”) microstimulation in several brain areas: rostrolateral rhombencephalon (RLR); dorsolateral mesencephalon (DLM); ventromedial diencephalon (VMD); and reticular nuclei. However, the quality and symmetry of rhythmic movements that would result from this in vitro burst activity have not been investigated in detail. In the present study, pharmacological microstimulation was applied to the above brain locomotor areas in semi-intact preparations from larval lamprey. First, bilateral pharmacological microstimulation in the VMD, DLM, or RLR initiated symmetrical swimming movements and coordinated muscle burst activity that were virtually identical to those during free swimming in whole animals. Unilateral microstimulation in these brain areas usually elicited asymmetrical undulatory movements. Second, with synaptic transmission blocked in the brain, bilateral pharmacological microstimulation in parts of the anterior (ARRN), middle (MRRN), or posterior (PRRN) rhombencephalic reticular nucleus also initiated symmetrical swimming movements and muscle burst activity. Stimulation in effective sites in the ARRN or PRRN initiated higher-frequency locomotor movements than stimulation in effective sites in the MRRN. Unilateral stimulation in reticular nuclei elicited asymmetrical rhythmic undulations or uncoordinated movements. The present study is the first to demonstrate in the lamprey that stimulation in higher-order locomotor areas (RLR, VMD, DLM) or reticular nuclei initiates and sustains symmetrical, well-coordinated locomotor movements and muscle activity. Finally, bilateral stimulation was a more physiologically realistic test of the function of these brain areas than unilateral stimulation.
Gastric Vagal Efferent Inhibition Evoked by Intravenous CRF Is Unrelated to Simultaneously Recorded Vagal Afferent Activity in Urethane-Anesthetized Rats
Authors: Adelson David W. , Kosoyan Hovsep P. , Wang Yuhua , Steinberg Justin Z. , Taché Yvette
Published: February 2007

Corticotropin-releasing factor (CRF) injected peripherally or released in response to stressful challenges to the organism reduces gastric tone and contractility, in part by vagal pathways. However, information on the changes in gastric vagal impulse activity evoked by peripheral CRF administration is entirely lacking. Using a novel “dual recording” method in urethane-anesthetized rats, vagal efferent (VE) and afferent (VA) impulse activities were recorded simultaneously from separate, fine bundles dissected from the ventral gastric vagus nerve branch innervating the glandular stomach. Activity records for 38 VA single units (SUs) and 33 VE SUs were sorted from multiunit records obtained from 13 preparations. Intravenous (iv) administration of saline had no effect on multiunit VE activity, whereas CRF (1 μg/kg, iv) immediately inhibited VE activity, reaching a nadir of 54 ± 8.0% of preinjection levels at 3.0 min postinjection. CRF (1 μg/kg, iv) inhibited 25/33 (75.8%) VE SUs and excited three of 33 (9.1%) VE SUs. In contrast to potent effects on VE activity, iv CRF did not alter multiunit VA activity. Single-unit analysis, however, revealed five of 38 (13.1%) VA SUs excited by iv CRF at widely varying latencies (suggesting an indirect mode of action) and one inhibited VA SU. VA SUs excited after iv CRF did not respond during gastric distention and vice versa. These experiments are the first to use simultaneous recording of gastric VA and VE units. The data demonstrate a predominantly inhibitory influence of iv CRF on VE outflow to the hindstomach, not driven by gastric vagovagal reflex activity.
Genetic Alterations and Their Relationship in the Phosphatidylinositol 3-Kinase/Akt Pathway in Thyroid Cancer
Authors: Hou Peng , Liu Dingxie , Shan Yuan , Hu Shuiying , Studeman Kimberley , Condouris Stephen , Wang Yangang , Trink Ariel , El-Naggar Adel K. , Tallini Giovanni , Vasko Vasily , Xing Mingzhao
Published: February 2007

Purpose: To investigate the overall occurrence and relationship of genetic alterations in the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in thyroid tumors and explore the scope of this pathway as a therapeutic target for thyroid cancer.

Experimental Design: We examined collectively the major genetic alterations and their relationship in this pathway, including PIK3CA copy number gain and mutation, Ras mutation, and PTEN mutation, in a large series of primary thyroid tumors.

Results: Occurrence of any of these genetic alterations was found in 25 of 81 (31%) benign thyroid adenoma (BTA), 47 of 86 (55%) follicular thyroid cancer (FTC), 21 of 86 (24%) papillary thyroid cancer (PTC), and 29 of 50 (58%) anaplastic thyroid cancer (ATC), with FTC and ATC most frequently harboring these genetic alterations. PIK3CA copy gain was associated with increased PIK3CA protein expression. A mutual exclusivity among these genetic alterations was seen in BTA, FTC, and PTC, suggesting an independent role of each of them through the PI3K/Akt pathway in the tumorigenesis of the differentiated thyroid tumors. However, coexistence of these genetic alterations was increasingly seen with progression from differentiated tumor to undifferentiated ATC. Their coexistence with BRAF mutation was also frequent in PTC and ATC.

Conclusions: The data provide strong genetic implication that aberrant activation of PI3K/Akt pathway plays an extensive role in thyroid tumorigenesis, particularly in FTC and ATC, and promotes progression of BTA to FTC and to ATC as the genetic alterations of this pathway accumulate. Progression of PTC to ATC may be facilitated by coexistence of PI3K/Akt pathway–related genetic alterations and BRAF mutation. The PI3K/Akt pathway may thus be a major therapeutic target in thyroid cancers.
The Suppression of Aurora-A/STK15/BTAK Expression Enhances Chemosensitivity to Docetaxel in Human Esophageal Squamous Cell Carcinoma
Authors: Tanaka Eiji , Hashimoto Yosuke , Ito Tetsuo , Kondo Kan , Higashiyama Motoshige , Tsunoda Shigeru , Ortiz Cristian , Sakai Yoshiharu , Inazawa Johji , Shimada Yutaka
Published: February 2007

Purpose: We previously reported that the expression of Aurora-A was frequently up-regulated in human esophageal squamous cell carcinoma (ESCC) tissues as well as cell lines and the up-regulation contributed to a poor prognosis. In this study, we assessed the possibility of Aurora-A suppression as a therapeutic target for ESCC using ESCC cell lines.

Experimental Design: We established subclones using vector-based short hairpin RNA (shRNA). Then, we investigated the effect of Aurora-A suppression on proliferation and cell cycle changes in vitro. Next, chemosensitivity against docetaxel was investigated by tetrazolium salt–based proliferation assay (WST assay) and cell number determinations, and furthermore, the type of cell death induced by docetaxel was analyzed by flow cytometry. Finally, to examine the effect of Aurora-A shRNA on proliferation and chemosensitivity against docetaxel in vivo, a s.c. tumor formation assay in nude mice was done.

Results: We established two genetically different stable cell lines (510 A and 1440 A) in which levels of Aurora-A were reduced. Cell growth was inhibited by 38.7% in 510 A and by 24.3% in 1440 A in vitro compared with empty vector–transfected controls (510 m and 1440 m), and this growth inhibition was mediated through G2-M arrest as confirmed by flow cytometry. Next, in a WST assay, the IC50 for Aurora-A shRNA-transfected cells was lower than that of empty vector–transfected cells (510 A, 2.7 × 10−7 mol/L; 510 m, 4.8 × 10−7 mol/L; 1440 A, 2.6 × 10−7 mol/L; 1440 m, 4.9 × 10−7 mol/L). In addition, 0.3 nmol/L docetaxel induced a notable level of apoptosis in Aurora-A shRNA-transfected cells compared with empty vector–transfected cells. In the assay of s.c. tumors in nude mice, tumor growth in 510 A was inhibited by 36.1% compared with that in 510 m, and in tumors treated with docetaxel, the suppression of Aurora-A resulted in 44.0% tumor growth suppression in vivo.

Conclusions: These results indicated that Aurora-A might play an important role in chemosensitivity to docetaxel, and the suppression of its expression might be a potential therapeutic target for ESCC.
Predictors of Resistance to Preoperative Trastuzumab and Vinorelbine for HER2-Positive Early Breast Cancer
Authors: Harris Lyndsay N. , You Fanglei , Schnitt Stuart J. , Witkiewicz Agnes , Lu Xin , Sgroi Dennis , Ryan Paula D. , Come Steven E. , Burstein Harold J. , Lesnikoski Beth-Ann , Kamma Madhavi , Friedman Paula N. , Gelman Rebecca , Iglehart J. Dirk , Winer Eric P.
Published: February 2007

Purpose: To assess pathologic complete response (pCR), clinical response, feasibility, safety, and potential predictors of response to preoperative trastuzumab plus vinorelbine in patients with operable, human epidermal growth factor receptor 2 (HER2)–positive breast cancer.

Experimental Design: Forty-eight patients received preoperative trastuzumab and vinorelbine weekly for 12 weeks. Single and multigene biomarker studies were done in an attempt to identify predictors of response.

Results: Eight of 40 (20%) patients achieved pCR (95% confidence interval, 9-36%). Of 9 additional patients recruited for protocol-defined toxicity analysis, 8 were evaluable; 42 of 48 (88%) patients had clinical response (16 patients, clinical complete response; 26 patients, clinical partial response). T1 tumors more frequently exhibited clinical complete response (P = 0.05) and showed a trend to exhibit pCR (P = 0.07). Five (13%) patients experienced grade 1 cardiac dysfunction during preoperative treatment. Neither HER2 nor estrogen receptor status changed significantly after exposure to trastuzumab and vinorelbine. RNA profiling identified three top-level clusters by unsupervised analysis. Tumors with extremes of response [pCR (n = 3) versus nonresponse (n = 3)] fell into separate groups by hierarchical clustering. No predictive genes were identified in pCR tumors. Nonresponding tumors were more likely to be T4 stage (P = 0.02) and express basal markers (P < 0.00001), growth factors, and growth factor receptors. Insulin-like growth factor-I receptor membrane expression was associated with a lower response rate (50% versus 97%; P = 0.001).

Conclusions: Preoperative trastuzumab plus vinorelbine is active and well tolerated in patients with HER2-positive, operable, stage II/III breast cancer. HER2-overexpressing tumors with a basal-like phenotype, or with expression of insulin-like growth factor-I receptor and other proteins involved in growth factor pathways, are more likely to be resistant to this regimen.
Preclinical In vivo Study of New Insulin-Like Growth Factor-I Receptor–Specific Inhibitor in Ewing's Sarcoma
Authors: Manara Maria C. , Landuzzi Lorena , Nanni Patrizia , Nicoletti Giordano , Zambelli Diana , Lollini Pier Luigi , Nanni Cristina , Hofmann Francesco , García-Echeverría Carlos , Picci Piero , Scotlandi Katia
Published: February 2007

Purpose: Small-molecule insulin-like growth factor-I receptor (IGF-IR)-specific tyrosine kinase inhibitors have been recently proposed as clinically viable approaches to impair IGF-IR functions. NVP-AEW541 seems one of the most promising agents. In this article, we point out its effects against migration, metastasis, vasculogenicity, and angiogenesis of Ewing's sarcoma cells.

Experimental Design: In vivo NVP-AEW541 effectiveness was analyzed against TC-71 Ewing's sarcoma growth and bone metastasis after cell inoculation in athymic mice. Activity of the compound against angiogenesis as well as vasculogenesis properties was also considered both in vitro and in xenografts. Serum glucose, urea, transaminase levels, as well as other signs of distress were checked in mice treated with the IGF-IR inhibitor.

Results: Significant inhibition of migration, metastasis, vasculogenicity, and angiogenesis was recorded after treatment of Ewing's sarcoma cells with NVP-AEW541. In view of its application and the similarity of insulin receptor and IGF-IR, diabetogenic side effects were considered. We observed a significant decrease of glucose blood serum due to increased glucose uptake at cellular level and an increase in urea concentration. Moreover, an initial weight loss was observed in mice bearing tumors. All these side effects were similarly detected in mice treated with vincristine. After the first days of treatment, all the animals started to grow again.

Conclusions: Our results globally reinforce the idea that IGF-IR inhibitor NVP-AEW541 could have a role in future combined therapies and suggest to pursue a thorough molecular analysis of the metabolic activity of IGF-IR to avoid possible side effects of these inhibitors.
First Study of the Safety, Tolerability, and Pharmacokinetics of CP-724,714 in Patients with Advanced Malignant Solid HER2-Expressing Tumors
Authors: Munster Pamela N. , Britten Carolyn D. , Mita Monica , Gelmon Karen , Minton Susan E. , Moulder Stacy , Slamon Dennis J. , Guo Feng , Letrent Stephen P. , Denis Louis , Tolcher Anthony W.
Published: February 2007

Purpose: To test the tolerability, safety, and recommended phase II dose of CP-724,714, a reversible, highly selective, oral HER2 tyrosine kinase inhibitor in patients with advanced solid tumor malignancies that express HER2.

Experimental Design: A phase I trial evaluated escalating doses of CP-724,714, administered daily in 21-day cycles. Pharmacokinetics/pharmacodynamics were evaluated in serial blood samples and in pretreatment and posttreatment tumor and skin biopsies.

Results: Thirty female patients [median age, 51 years (range, 37-71); median performance status, 1 (range, 0-1)] received CP-724,714 at four dose levels: 250 mg once daily (4 patients), 250 mg twice daily (15 patients), 250 mg thrice daily (6 patients), and 400 mg twice daily (5 patients). Dosing at 400 mg twice daily and 250 mg thrice daily was not feasible due to reversible, cholestatic liver dysfunction. Treatment-related adverse events were nausea (58%), asthenia (23%), hyperbilirubinemia (27%), elevated transaminases (30%), and skin rash (30%); neither diarrhea nor cardiomyopathy was observed. No objective responses were observed in 28 evaluable patients; 8 (29%) patients had stable disease. Twenty-seven (96%) patients received prior trastuzumab and were heavily pretreated (median prior chemotherapy, 6; range, 1-11). Systemic exposure exceeded the in vivo efficacy threshold required in preclinical studies.

Conclusions: Dose-limiting toxicities included hyperbilirubinemia, elevated alanine aminotransferase, thrombocytopenia and pulmonary embolus. Although the protocol-specified maximum tolerated dose of CP-724,714 was 250 mg thrice daily, the recommended phase II dose was 250 mg twice daily due to excessive late-cycle hepatotoxicity. Despite extensive prior treatment, 29% of patients had stable disease. A phase II trial has been initiated in patients with breast cancer.
Analysis of Specific Transcriptional Regulators as Early Predictors of Independent Prognostic Relevance in Resected Colorectal Cancer
Authors: Maurer Gabriele D. , Leupold Joerg H. , Schewe Denis M. , Biller Tobias , Kates Ronald E. , Hornung Hans-Martin , Lau-Werner Ulla , Post Stefan , Allgayer Heike
Published: February 2007

Purpose: Prognostic studies on transcription factors acting at specific promoter elements have never been done so far. However, in tumors with long necessary follow-up, such as colorectal cancer, early-risk predictors would be needed. The invasion-related gene u-PAR is regulated via an activator protein 2 (AP-2)/Sp1 (−152/−135) and an AP-1 binding promoter motif (−190/−171), mediating u-PAR induction by K-Ras and Src. The present study was done to give first evidence for early prognostic relevance of transcription factors differentially bound to the u-PAR promoter, and their molecular inducers, in colorectal cancer.

Experimental Design: Tumor/normal tissues of 92 prospectively followed (median = 26.3 months) patients were analyzed for Src activity/protein, K-ras mutations, and transcription factor binding to both u-PAR promoter motifs (in vivo gel shift, kinase assay, and PCR).

Results: Kaplan-Meier/Mantel-Cox analysis showed a significant correlation among elevated Sp1/Sp3 binding to region −152/−135 (P = 0.002 and P = 0.006), the combinations of Sp1/AP-2 and Sp1/AP-1 binding to both motifs (P = 0.010 and P = 0.005), and Sp1 binding/high Src protein in tumors (P < 0.001), with poor survival. Survival decreased with the number of bound transcription factors to both motifs, with binding of three factors defining a high-risk group (P = 0.021). In multivariate analysis, elevated Sp1 binding, combinations of Sp1/AP-2 binding and Sp1/AP-1 binding, or Sp1 binding/high Src were independent prognostic variables; u-PAR expression itself being not yet prognostic. A first molecular staging model (CART) was defined, providing novel early high-risk groups (mean survival time as low as for non-curatively resected patients) from these variables.

Conclusions: This study defines transcription factors acting at specific promoter elements of an invasion-related gene, mediating specific signaling, as novel, independent, early predictors of prognosis in colorectal cancer.
Phase I Trial of Intraperitoneal Gemcitabine in the Treatment of Advanced Malignancies Primarily Confined to the Peritoneal Cavity
Authors: Morgan Robert J. , Synold Timothy W. , Xi Bixin , Lim Dean , Shibata Stephen , Margolin Kim , Schwarz Roderich E. , Leong Lucille , Somlo George , Twardowski Przemyslaw , Yen Yun , Chow Warren , Tetef Merry , Lin Paul , Paz Benjamin , Koczywas Mariana , Wagman Lawrence , Chu David , Frankel Paul , Stalter Susan , Doroshow James H.
Published: February 2007

Purpose: To determine the maximally tolerated dose, toxicity, and pharmacokinetics of i.p. gemcitabine.

Experimental Design: Patients had peritoneal carcinomatosis. Gemcitabine (40, 80, 120, or 160 mg/m2) was administered into the peritoneal cavity in 2 L of warmed saline on days 1, 4, 8, and 12 of a 28-day cycle.

Results: Thirty patients received 63 (median, 2; range, 0-6) courses. Tumors included ovary (14), uterus (2), colon (6), pancreas (3), and others (5). Dose-limiting toxicity included nausea, vomiting, diarrhea, dyspnea, fatal respiratory failure, and grade 3 elevation of alanine aminotransferase in three patients. Hematologic toxicity and pain were ≤grade 2. Three patients had decreased or resolved ascites. Of 19 patients evaluable for response, 10 had stable disease (median, 3.5 courses) and 9 had progressive disease. The median peak peritoneal concentration was 1,116-fold (range, 456-1,886) higher than the peak plasma level. Plasma and peritoneal levels were undetectable within 8 to 12 h. At 120 mg/m2, the median peritoneal area under the concentration versus time curve (AUC) was 82,612 ng/mL × h (range, 53,296-199,830) and the plasma AUC was 231 ng/mL × h (range, 47.6-259.5). The mean peritoneal advantage (AUCperitoneal/AUCplasma) was 847 (range, 356-1,385).

Conclusions: I.p. administration of gemcitabine is tolerated within the tested dosage range. Technical problems with the Porta-Cath device and i.p. therapy per se may have been exacerbated by the enrollment of many patients with a variety of advanced i.p. diseases. Given the significant increase in local dose intensity and the documented activity of this drug, this agent may be an excellent candidate for i.p. therapy in optimally debulked ovarian cancer, either alone or in combination.
CABYR Is a Novel Cancer-Testis Antigen in Lung Cancer
Authors: Luo Chonglin , Xiao Xueyuan , Liu Danhui , Chen Shaosong , Li Mingying , Xu Anjian , Liu Jifu , Gao Shugeng , Wu Shanshan , He Dacheng
Published: February 2007

Purpose: Cancer-testis (CT) antigens are often expressed in a proportion of tumors of various types. Their restricted normal tissue expression and immunogenicity make them potential targets for immunotherapy. CABYR is a calcium-binding tyrosine phosphorylation–regulated fibrous sheath protein initially reported to be testis specific and subsequently shown to be present in brain tumors. This study was to determine whether CABYR is a novel CT antigen in lung cancer.

Experimental Design: mRNA expression of CABYR-a/b (combination of CABYR-a and CABYR-b) and CABYR-c was examined in 36 lung cancer specimens, 14 cancer cell lines, and 1 normal cell line by conventional and real-time reverse transcription-PCR. Protein expression of CABYR was analyzed in 50 lung cancer tissues by immunohistochemistry. Antibodies specific to CABYR were analyzed in sera from 174 lung cancer patients and 60 healthy donors by ELISA and Western blot.

Results: mRNA expression of CABYR-a/b and CABYR-c was observed, respectively, in 13 and 15 of 36 lung cancer tissues as well as in 3 and 5 of 14 cancer cell lines, whereas neither of them was observed in adjacent noncancerous tissues or the normal cell line. Protein expression of CABYR-a/b and CABYR-c was observed, respectively, in 20 and 19 of 50 lung cancer tissues. IgG antibodies specific to CABYR-a/b and CABYR-c were detected, respectively, in 11% and 9% of sera from lung cancer patients but not from the 60 healthy donors.

Conclusion: CABYR is a novel CT antigen in lung cancer and may be a promising target for immunotherapy for lung cancer patients.
Suppression of BRAF/MEK/MAP Kinase Pathway Restores Expression of Iodide-Metabolizing Genes in Thyroid Cells Expressing the V600E BRAF Mutant
Authors: Liu Dingxie , Hu Shuiying , Hou Peng , Jiang David , Condouris Stephen , Xing Mingzhao
Published: February 2007

Purpose: The V600E BRAF mutant plays an important role in the pathogenesis of papillary thyroid cancer (PTC) and is associated with loss of expression of thyroid iodide-metabolizing genes. This study was done to investigate the restorability of expression of these genes by suppressing the BRAF/extracellular signal-regulated kinase kinase (MEK)/mitogen-activated protein (MAP) kinase pathway in V600E BRAF–harboring thyroid cells and to explore the mechanisms involved.

Experimental Design: We used inducible expression of V600E BRAF, small interfering RNA transfection, and MEK-specific inhibitor to alter the MAP kinase pathway activities and subsequently examined the changes in expression, promoter activities, and methylation status of thyroid genes.

Results: MEK inhibitor U0126 or cessation of V600E BRAF expression in PCCL3 cells restored expression of thyroid genes silenced by induced expression of V600E BRAF. U0126 also restored the expression of these genes in V600E BRAF–harboring PTC-derived NPA cells. Knockdown of BRAF by specific small interfering RNA restored expression of some of these genes in NPA cells. Luciferase reporter assay using thyroid-stimulating hormone receptor gene as a model showed that the promoter activity was modulated by the MAP kinase pathway. Promoter methylation in association with DNA methyltransferase expression played a role in gene silencing by MAP kinase pathway in NPA cells.

Conclusions: We showed the restorability of expression of thyroid iodide-metabolizing genes silenced by V600E BRAF, and linked this process to gene methylation in PTC cells. The results provide clinical implications that therapeutic targeting at the BRAF/MEK/MAP kinase pathway may be a good approach in restoring thyroid gene expression for effective radioiodine therapy for BRAF mutation-harboring PTC.
Metabolism and Anticancer Activity of the Curcumin Analogue, Dimethoxycurcumin
Authors: Tamvakopoulos Constantin , Dimas Konstantinos , Sofianos Zacharias D. , Hatziantoniou Sophia , Han Zhiyong , Liu Zhong-Li , Wyche James H. , Pantazis Panayotis
Published: February 2007

Purpose: The plant-derived compound curcumin has shown promising abilities as a cancer chemoprevention and chemotherapy agent in vitro and in vivo but exhibits poor bioavailability. Therefore, there is a need to investigate modified curcumin congeners for improved anticancer activity and pharmacokinetic properties.

Experimental Design: The synthetic curcumin analogue dimethoxycurcumin was compared with curcumin for ability to inhibit proliferation and apoptosis of human HCT116 colon cancer cells in vitro by estimating the GI50 and LC50 values and detecting the extent of apoptosis by flow cytometry analysis of the cell cycle. Metabolic stability and/or identification of metabolites were evaluated by recently developed mass spectrometric approaches after incubation with mouse and human liver microsomes and cancer cells in vitro. Additionally, circulating levels of dimethoxycurcumin and curcumin were determined in mice following i.p. administration.

Results: Dimethoxycurcumin is significantly more potent than curcumin in inhibiting proliferation and inducing apoptosis in HCT116 cells treated for 48 h. Nearly 100% of curcumin but <30% of dimethoxycurcumin was degraded in cells treated for 48 h, and incubation with liver microsomes confirmed the limited metabolism of dimethoxycurcumin. Both compounds were rapidly degraded in vivo but dimethoxycurcumin was more stable.

Conclusions: Compared with curcumin, dimethoxycurcumin is (a) more stable in cultured cells, (b) more potent in the ability to kill cancer cells by apoptosis, (c) less extensively metabolized in microsomal systems, and (d) more stable in vivo. It is likely that the differential extent of apoptosis induced by curcumin and dimethoxycurcumin in vitro is associated with the metabolite profiling and/or the extent of stability.
Prospect of Targeting the CD40 Pathway for Cancer Therapy
Authors: Vonderheide Robert H.
Published: February 2007

The cell surface molecule CD40 is a member of the tumor necrosis factor receptor superfamily and is broadly expressed by immune, hematopoietic, vascular, epithelial, and other cells, including a wide range of tumor cells. CD40 itself lacks intrinsic kinase or other signal transduction activity but rather mediates its diverse effects via an intricate series of downstream adapter molecules that differentially alter gene expression depending on cell type and microenvironment. As a potential target for novel cancer therapy, CD40 may mediate tumor regression through both an indirect effect of immune activation and a direct cytotoxic effect on the tumor, resulting in a “two-for-one” mechanism of action of CD40 agonists. Several drug formulations that target the CD40 pathway have undergone phase 1 clinical evaluation in advanced-stage cancer patients, and initial findings show objective clinical responses and immune modulation in the absence of major toxicity.