bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of resist surface characteristics on film-pulling velocity in immersion lithography
Authors: Schuetter S. , Shedd T. , Nellis G. , Romano A. , Dammel R. , Padmanaban M. , Houlihan F. , Krawicz A. , Lin G. , Rahman D. , Chakrapani S. , Neisser M. , Van Peski C.
Published: December 2006

In an immersion lithography system, liquid loss may occur at the receding contact line associated with the free surface of the liquid that is confined between the stationary lens apparatus and the moving wafer (or substrate). This deposited liquid may lead to defects in the printed features. The critical velocity for liquid loss is a function of the substrate surface properties, the geometry of the immersion lens, and the properties of the immersion liquid. This article investigates the effect of both the fluid properties of the immersion liquid and surface characteristics of the substrate on liquid loss velocity. Specifically, glycerine-water mixtures of varying viscosities were tested to determine the effect on critical velocity. In this article the authors experimentally investigate the impact of the partition coefficient or logP, which is a measure of the relative hydrophobicity of different surfaces. The correlation is used to approximately isolate the effect of the static, receding contact angle from logP on the critical velocity for liquid loss and an additional correction term for the correlation is proposed based on correlating these results.
Etching of Pyrex glass substrates by inductively coupled plasma reactive ion etching for micro/nanofluidic devices
Authors: Jung Hyun Chul , Lu Wu , Wang Shengnian , Lee L. James , Hu Xin
Published: December 2006

The inductively coupled plasma (ICP) reactive ion etching of Pyrex glass was carried out using SF6∕Ar plasmas. The etch rate and surface and sidewall smoothnesses were investigated systematically through their dependence on bias voltage, ICP power, pressure, flow rate, and cathode temperature. Near vertical sidewalls and smooth etched surfaces were obtained by optimized etching parameters. The maximum etch rate, 0.65μm∕min, was achieved at a pressure of 5mTorr, a bias of 720V, and an ICP power of 2500W. Microfluidic devices with various sizes on Pyrex glass have been designed and fabricated. Two types of electrokinetic flow patterns, which are extensional and rotational flows under different biases, have been successfully demonstrated with five cross microfluidic devices.
Mechanisms of isotropic and selective etching between SiGe and Si
Authors: Caubet V. , Beylier C. , Borel S. , Renault O.
Published: December 2006

The impact of SiGe isotropic etching selectively to Si on structures such as silicon on nothing or gate all around has been evaluated through the electrical performances of devices that were subjected to different etching processes. New prospects and evolutions in microelectronics can be foreseen, thanks to the development of the opposite process, i.e., the isotropic etching of Si selectively to SiGe. This process is based on the passivation of the SiGe layer during etching in a chemical dry etching tool. Scanning electron microscopy and x-ray photoelectron spectroscopy studies allowed the analysis of the influence of each parameter (gas mixture, pressure, and microwave power) and the proposal of etching and passivation mechanisms. This led to the definition of a highly selective Si:SiGe process.
Pulse reverse plating for uniform nickel height in zone plates
Authors: Lindblom M. , Hertz H. M. , Holmberg A.
Published: December 2006

Nickel soft x-ray zone plates are fabricated by through-mask electroplating. The authors report on how a uniform nickel thickness can be obtained over the entire zone plate using pulse and pulse reverse plating. If the plating is carried out at a constant current the nickel thickness has been observed to decrease with radius. This results in lower outer zones and reduced diffraction efficiency in the outer parts of the zone plates. Here they show that the height profile can be controlled by adjusting the current density of the pulses. A high current density is found to primarily affect the edges while a low current density was observed to affect the central parts of the structures. This is true for both cathodic and anodic currents, which means that local plating and dissolution rates can be adjusted to obtain a uniform mass distribution.
Arrayed miniature electron beam columns for mask making
Authors: Spallas J. P. , Silver C. S. , Muray L. P.
Published: December 2006

A significant problem facing integrated circuit mass-production lithography at future technology generations is the throughput of mask writers. Novelx has developed the technologies to build a distributed multiaxial parallel beam system consisting of a monolithic array of individually correctable electron beam columns. These technologies can be scaled to manufacture a system with a sufficient number of columns to write a single mask at the 32nm node with a write time of an order of magnitude faster than what is forecasted at the back end of the 45nm node. The key to these technologies is a new type of miniature electron beam column fabricated and assembled using manufacturable processes. Both single and 1×4 multicolumn systems have been assembled and tested, and have demonstrated 90nm lithography. The columns in these systems operate at low voltage and are all electrostatic. The lenses are monolithically fabricated bonded stacks of micromachined silicon and glass. The monolithic lenses are assembled onto a single package. The multicolumn lens stacks consist of four independent and electrically isolated lenses. The silicon and package are scalable for continued miniaturization, and can be fabricated in larger monolithic arrays of individually correctable beams. The authors show that the 1×4 column system currently in operation can be scaled to a 4×4 column system and that a mask writer using the 4×4 column system is capable of writing a single mask at the 32nm dynamic random access memory 1∕2 pitch node in 10h.
Directly patterning ferroelectric films by nanoimprint lithography with low temperature and low pressure
Authors: Hsieh K. C. , Chen H. L. , Lin C. H. , Lee C. Y.
Published: December 2006

In this article, the authors demonstrate an imprint method for patterning ferroelectric films. In contrast to conventional nanoimprint lithography, the patterned mold is directly imprinted in a ferroelectric film or a metal/ferroelectric film bilayer structure. In general, direct imprint in a ferroelectric or metal film needs ultrahigh pressure or temperature to form patterns. In this article, the authors improve the direct imprint processes by using a sharp mold and an underlying soft gel film for the reduction of the imprint pressure and temperature. The imprint pressure can be reduced to be compatible with the conventional nanoimprint instrument. The authors also successfully use the metal/ferroelectric bilayer structure to overcome the pattern flattened problem in a gel film. The cover metal layer can also be the upper conductive layer in the ferroelectric application. For direct contact of the metal film with mold, no surfactant should be coated on the surface of mold. It also indicates that no mold-rework processes are necessary for this direct imprint ferroelectric film method.
Generation of isofocal target patterns using process modeling during optical proximity correction
Authors: Melvin Lawrence S. , Croffie Ebo , Biswas Abani
Published: December 2006

Isofocal patterns produce the most ideal manufacturing conditions on a reticle, however, most semiconductor designs contain few isofocal features. A new way of looking at defocus conditions based on the change in intensity with respect to nominal focus [L. S. Melvin III et al., J. Vac. Sci. Technol. B 23, 2631 (2005)]—referred to as IΔ—can be used to resize the target pattern to isofocal dimensions. The pattern is quantitatively analyzed using IΔ to find modified pattern shapes that give isofocal target patterns for optical proximity correction and/or resolution enhancement techniques. The target pattern is then made isofocal by resizing the pattern to the modified shape prior to the use of optical proximity correction and/or resolution enhancement techniques. Results of this concept demonstrate excellent improvement in the feature robustness of different features at various defocus conditions. The proposed isofocal targeting method can be applied to layers where trade-offs between pattern shape and final pattern fidelity may be manipulated to improve process depth of focus.
Chemical and Spectroscopic Evidence for an Fe
V
-Oxo Complex
Authors: de Oliveira Filipe Tiago , Chanda Arani , Banerjee Deboshri , Shan Xiaopeng , Mondal Sujit , Que Lawrence , Bominaar Emile L. , Münck Eckard , Collins Terrence J.
Published: December 2006

Iron(V)-oxo species have been proposed as key reactive intermediates in the catalysis of oxygen-activating enzymes and synthetic catalysts. Here, we report the synthesis of [Fe(TAML)(O)]
–
in nearly quantitative yield, where TAML is a macrocyclic tetraamide ligand. Mass spectrometry, Mössbauer, electron paramagnetic resonance, and x-ray absorption spectroscopies, as well as reactivity studies and density functional theory calculations show that this long-lived (hours at –60°C) intermediate is a spin
S
= 1/2 iron(V)-oxo complex. Iron-TAML systems have proven to be efficient catalysts in the decomposition of numerous pollutants by hydrogen peroxide, and the species we characterized is a likely reactive intermediate in these reactions.
Nuclear Activity of MLA Immune Receptors Links Isolate-Specific and Basal Disease-Resistance Responses
Authors: Shen Qian-Hua , Saijo Yusuke , Mauch Stefan , Biskup Christoph , Bieri Stéphane , Keller Beat , Seki Hikaru , Ülker Bekir , Somssich Imre E. , Schulze-Lefert Paul
Published: December 2006

Plant immune responses are triggered by pattern recognition receptors that detect conserved pathogen-associated molecular patterns (PAMPs) or by resistance (R) proteins recognizing isolate-specific pathogen effectors. We show that in barley, intracellular mildew A (MLA) R proteins function in the nucleus to confer resistance against the powdery mildew fungus. Recognition of the fungal avirulence A10 effector by MLA10 induces nuclear associations between receptor and WRKY transcription factors. The identified WRKY proteins act as repressors of PAMP-triggered basal defense. MLA appears to interfere with the WRKY repressor function, thereby de-repressing PAMP-triggered basal defense. Our findings reveal a mechanism by which these polymorphic immune receptors integrate distinct pathogen signals.
Comparison of Itraconazole and Fluconazole Treatments in a Murine Model of Coccidioidal Meningitis
Authors: Kamberi Perparim , Sobel Raymond A. , Clemons Karl V. , Waldvogel Andreas , Striebel Joan M. , Williams Paul L. , Stevens David A.
Published: December 2006

Coccidioidal meningitis (CM) is a devastating disease that requires long-term therapy and for which there is little hope of a cure. A model was used to compare the efficacies of itraconazole and fluconazole. CD-1 mice were infected intrathecally with 30 to 36 viable arthroconidia of
Coccidioides
. Oral therapy with cyclodextrin (control) or itraconazole or fluconazole at 10, 25, or 50 mg/kg of body weight twice daily (BID) was given for 12 days, from day 3 of infection. Treatment with both antifungals at all doses prolonged survival compared with that of the control treatment (
P
< 0.01 to 0.0001). At 50 mg/kg, itraconazole and fluconazole were equivalent, whereas itraconazole at 10 or 25 mg/kg prolonged survival compared to that achieved with fluconazole at these dosages (
P
< 0.05 and 0.01, respectively). Early histologic analysis (10 days of treatment) with 50 mg/kg BID itraconazole or fluconazole showed suppression of CM in all five animals per group; in quantitative cultures, three of three animals from each group had no detectable infection in the brain, spinal cord, or a site of secondary infection, the lungs. In contrast, four of seven controls showed mild to severe meningitis, with arteritis detected in three animals. In a short-term organ clearance study, 5 days of treatment with 10 or 50 mg/kg BID itraconazole or fluconazole reduced the tissue burdens in the brain and spinal cord compared to the tissue burdens in the controls (
P
< 0.02 to 0.0003). Fluconazole at 10 mg/kg did not reduce the fungal burden in secondary sites, the lungs and kidneys, whereas this itraconazole dose was more effective in clearing the fungi from both organs (
P
< 0.05 and
P
< 0.001, respectively). At 50 mg/kg, itraconazole and fluconazole were equivalent in clearing the fungi from the brain and kidney, but itraconazole was superior to fluconazole in clearing the fungi from the spinal cord and lungs (
P
< 0.05). Thus, both itraconazole and fluconazole were effective at controlling CM, but neither eliminated
Coccidioides
from tissues. Overall, itraconazole was more efficacious on an mg/kg basis; at high doses they were similarly effective.
Impact of Nevirapine (NVP) Plasma Concentration on Selection of Resistant Virus in Mothers Who Received Single-Dose NVP To Prevent Perinatal Human Immunodeficiency Virus Type 1 Transmission and Persistence of Resistant Virus in Their Infected Children
Authors: Chaix Marie-Laure , Ekouevi Didier Koumavi , Peytavin Gilles , Rouet François , Tonwe-Gold Besigin , Viho Ida , Bequet Laurence , Amani-Bosse Clarisse , Menan Hervé , Leroy Valériane , Rouzioux Christine , Dabis François
Published: December 2006

Nonnucleoside reverse transcriptase inhibitor resistance following the use of single-dose nevirapine (sdNVP) for the prevention of mother-to-child transmission (PMTCT) remains a concern. In the ANRS-1201/1202 Ditrame study, conducted in Abidjan, Côte d'Ivoire, a short-course regimen of zidovudine was associated with sdNVP for PMTCT. In this study, we estimate the frequency of NVP resistance and its relationship with NVP concentration in mothers. Genotypic resistance analysis was performed on mothers' plasma samples at week 4 postpartum (PP) and on human immunodeficiency virus (HIV) DNA in peripheral blood mononuclear cells (PBMC) when an NVP resistance mutation was detected. The same tests were performed for the infected children at week 4, month 3, and month 12. Mothers' NVP plasma concentrations were measured at 48 h PP. Twenty-one (33%) of the 63 women selected had NVP-resistant (NVP-R) virus at week 4 PP. The median plasma NVP concentration was 598 ng/ml for the mothers without NVP-R virus compared to 851 ng/ml for the mothers harboring NVP-R virus (
P
= 0.014). NVP-R mutations were detected in the HIV DNA of 15/20 women. Plasma NVP-R mutations were detectable in 6 of 26 infected children at week 4. All 6 children had detectable NVP-R mutations in HIV DNA of PBMC. Blood samples taken at month 3 (1 child) and month 12 (1 child) revealed the persistence of NVP-R mutations in plasma and cells. Emergence of NVP-R virus in mothers is strongly correlated with a high level of plasma NVP concentration, owing to a prolonged postpartum period of viral replication under NVP selective pressure. The follow-up of the cohort demonstrates the prolonged archive of resistant virus.
Virally Activated CD8 T Cells Home toMycobacterium bovisBCG-Induced Granulomas but Enhance Antimycobacterial Protection Only in Immunodeficient Mice
Authors: Hogan Laura H. , Co Dominic O. , Karman Jozsef , Heninger Erika , Suresh M. , Sandor Matyas
Published: December 2006

The effect of secondary infections on CD4 T-cell-regulated chronic granulomatous inflammation is not well understood. Here, we have investigated the effect of an acute viral infection on the cellular composition and bacterial protection inMycobacterium bovisstrain bacille Calmette-Guérin (BCG)-induced granulomas using an immunocompetent and a partially immunodeficient murine model. Acute lymphocytic choriomeningitis virus (LCMV) coinfection of C57BL/6 mice led to substantial accumulation of gamma interferon (IFN-γ)-producing LCMV-specific T cells in liver granulomas and increased local IFN-γ. Despite traffic of activated T cells that resulted in a CD8 T-cell-dominated granuloma, the BCG liver organ load was unaltered from control levels. In OT-1 T-cell-receptor (TCR) transgenic mice, ovalbumin (OVA) immunization or LCMV coinfection of BCG-infected mice induced CD8 T-cell-dominated granulomas containing large numbers of non-BCG-specific activated T cells. The higher baseline BCG organ load in this CD8 TCR transgenic animal allowed us to demonstrate that OVA immunization and LCMV coinfection increased anti-BCG protection. The bacterial load remained substantially higher than in mice with a more complete TCR repertoire. Overall, the present study suggests that peripherally activated CD8 T cells can be recruited to chronic inflammatory sites, but their contribution to protective immunity is limited to conditions of underlying immunodeficiency.
The Psa Fimbriae of
Yersinia pestis
Interact with Phosphatidylcholine on Alveolar Epithelial Cells and Pulmonary Surfactant
Authors: Galván Estela M. , Chen Huaiqing , Schifferli Dieter M.
Published: December 2006

The pH 6 antigen (Psa) of
Yersinia pestis
consists of fimbriae with adhesive properties of potential importance for the pathogenesis of plague, including pneumonic plague. The Psa fimbriae mediate bacterial binding to human alveolar epithelial cells. The Psa fimbriae bound mostly to one component present in the total lipid extract from type II alveolar epithelial cells of the cell line A549 separated by thin-layer chromatography (TLC). The Psa receptor was identified as phosphatidylcholine (PC) by TLC using alkali treatment, molybdenum blue staining, and Psa overlays. The Psa fimbriae bound to PC in a dose-dependent manner, and binding was inhibited by phosphorylcholine (ChoP) and choline. Binding inhibition was dose dependent, although only high concentrations of ChoP completely blocked Psa binding to PC. In contrast, less than 1 μM of a ChoP-polylysine polymer inhibited specifically the adhesion of Psa-fimbriated
Escherichia coli
to PC, and type I (WI-26 VA4) and type II alveolar epithelial cells. These results indicated that the homopolymeric Psa fimbriae are multimeric adhesins. Psa also bound to pulmonary surfactant, which covers the alveolar surface as a product of type II alveolar epithelial cells and includes PC as the major component. The observed dose-dependent interaction of Psa with pulmonary surfactant was blocked by ChoP. Interestingly, surfactant did not inhibit Psa-mediated bacterial binding to alveolar cells, suggesting that both surfactant and cell membrane PC retain Psa-fimbriated bacteria on the alveolar surface. Altogether, the results indicate that Psa uses the ChoP moiety of PC as a receptor to mediate bacterial binding to pulmonary surfactant and alveolar epithelial cells.
Coactivating Signals for the Hepatic Lymphocyte Gamma Interferon Response toFrancisella tularensis
Authors: Wickstrum Jason R. , Hong Kee-Jong , Bokhari Sirosh , Reed Natalie , McWilliams Nicholas , Horvat Rebecca T. , Parmely Michael J.
Published: December 2006

The facultative intracellular bacteriumFrancisella tularensisis capable of causing systemic infections in various hosts, including mice and humans. The liver is a major secondary site ofF. tularensisinfection, but hepatic immune responses to the pathogen remain poorly defined. Immune protection against the pathogen is thought to depend on the cytokine gamma interferon (IFN-γ), but the cellular basis for this response has not been characterized. Here we report that natural killer cells from the livers of naïve uninfected mice produced IFN-γ when challenged with live bacteria in vitro and that the responses were greatly increased by coactivation of the cells with either recombinant interleukin-12 (IL-12) or IL-18. Moreover, the two cytokines had strong synergistic effects on IFN-γ induction. Neutralizing antibodies to either IL-12 or IL-18 inhibited IFN-γ production in vitro, and mice deficient in the p35 subunit of IL-12 failed to show IFN-γ responses to bacterial challenge either in vitro or in vivo. Clinical isolates of highly virulent type AFrancisella tularensissubsp.tularensisorganisms were comparable to the live attenuated vaccine strain ofFrancisella tularensissubsp.holarcticain their ability to induce IL-12 and IFN-γ expression. These findings demonstrate that cells capable of mounting IFN-γ responses toF. tularensisare resident within the livers of uninfected mice and depend on coactivation by IL-12 and IL-18 for optimum responses.
Cellular Pyrin Domain-Only Protein 2 Is a Candidate Regulator of Inflammasome Activation
Authors: Dorfleutner Andrea , Bryan Nicole B. , Talbott Siera J. , Funya Kristin N. , Rellick Stephanie L. , Reed John C. , Shi Xianglin , Rojanasakul Yon , Flynn Daniel C. , Stehlik Christian
Published: December 2006

Pyrin domain (PYD) proteins have recently emerged as important signaling molecules involved in the development of innate immunity against intracellular pathogens through activation of inflammatory mediator pathways. ASC is the central adaptor protein, which links pathogen recognition by PYD-containing pathogen recognition receptors, known as PYD-Nod-like receptors (NLR), PAN, PYPAF, NALP, Nod, and Caterpiller proteins, to the activation of downstream effectors, including activation of caspase-1 and NF-κB. Activation of these effectors occurs when specific protein complexes, known as inflammasomes, are formed. PYD signal transduction leads to inflammasome assembly and activation of specific effector proteins. It is modulated by a cellular PYD-only protein (cPOP1), which binds to ASC and interferes with the recruitment of ASC to activated PYD-NLRs. Here we describe the identification and characterization of a second cellular POP (cPOP2), which shows highest homology to the PYD of PAN1. cPOP2 binds to ASC and PAN1, thereby blocking formation of cryopyrin and PAN1-containing inflammasomes, activation of caspase-1, and subsequent processing and secretion of bioactive interleukin-1β. Existence of a second cPOP provides additional insights into inflammasome formation and suggests that POPs might be a common regulatory mechanism to “fine-tune” the activity of specific PYD-NLR family protein-containing inflammasomes.
HIGH-ENERGY ASPECTS OF ASTROPHYSICAL JETS
Authors: LEVINSON AMIR
Published: December 2006

Various aspects of the high-energy emission from relativistic jets associated with compact astrophysical systems are reviewed. The main leptonic and hadronic processes responsible for the production of high-energy γ-rays, very-high-energy neutrinos and ultra-high energy cosmic rays are discussed. Relations between the γγ pair production and photomeson production opacities are derived, and their consequences for the relative emission of γ-rays and neutrinos are examined. The scaling of the size and location of the various emission zones and other quantities with black hole mass and dimensionless luminosity is elucidated. The results are applied to individual classes of objects, including blazars, microquasars and gamma-ray bursts. It is concluded that if baryons are present in the jet at sufficient quantities, then under optimal conditions most systems exhibiting relativistic jets may be detectable by upcoming neutrino telescopes. An exception is the class of TeV blazars, for which γ-ray observations imply neutrino yields well below detection limit.
CaM kinase II activation and phospholamban phosphorylation by SNP in murine gastric antrum smooth muscles
Authors: Kim Minkyung , Perrino Brian A.
Published: December 2006

Elevations in the intracellular Ca2+concentration activate the serine/threonine protein kinase Ca2+/calmodulin-dependent protein kinase II (CaM kinase II). We tested the hypothesis that increased sarco(endo)plasmic reticulum Ca2+-ATPase activity by phospholamban (PLB) phosphorylation contributes to smooth muscle relaxation by elevating the sarcoplasmic reticulum (SR) Ca2+load and increasing the frequency of Ca2+release events from the SR. We have previously shown that caffeine or sodium nitroprusside (SNP) relaxes murine gastric fundus smooth muscles and increases PLB phosphorylation by CaM kinase II. These findings suggest that an increased SR Ca2+load increases the frequency of Ca2+transients from the SR and results in PLB phosphorylation by CaM kinase II, contributing to caffeine- or SNP-induced relaxation. The aim of the present study was to investigate the effects of SNP on CaM kinase II and PLB phosphorylation in gastric antrum smooth muscles. SNP or 8-bromo-cGMP decreased the basal tone and amplitudes of spontaneous phasic contractions and activated CaM kinase II. SNP-induced relaxation and CaM kinase II activation were blocked by [1,2,4]oxadizolo-[4,3α]quinoxaline-1-one (ODQ) and inhibited by cyclopiazonic acid (CPA) or KN-93. SNP also increased PLBSer16and PLBThr17phosphorylation. Both PLBSer16and Thr17phosphorylation were ODQ sensitive. However, only PLBThr17phosphorylation was inhibited by CPA or KN-93. These results suggest that CaM kinase II activation and PLB phosphorylation participate in the relaxant effect of SNP on murine gastric antrum smooth muscles through a nitric oxide/guanylyl cyclase/cGMP pathway.
Baroreflex sensitivity, blood pressure buffering, and resonance: what are the links? Computer simulation of healthy subjects and heart failure patients
Authors: van de Vooren Hedde , Gademan Maaike G. J. , Swenne Cees A. , TenVoorde Ben J. , Schalij Martin J. , Van der Wall Ernst E.
Published: December 2006

The arterial baroreflex buffers slow (<0.05 Hz) blood pressure (BP) fluctuations, mainly by controlling peripheral resistance. Baroreflex sensitivity (BRS), an important characteristic of baroreflex control, is often noninvasively assessed by relating heart rate (HR) fluctuations to BP fluctuations; more specifically, spectral BRS assessment techniques focus on the BP-to-HR transfer function around 0.1 Hz. Skepticism about the relevance of BRS to characterize baroreflex-mediated BP buffering is based on two considerations: 1) baroreflex-modulated peripheral vasomotor function is not necessarily related to baroreflex-HR transfer; and 2) although BP fluctuations around 0.1 Hz (Mayer waves) might be related to baroreflex BP buffering, they are merely a not-intended side effect of a closed-loop control system. To further investigate the relationship between BRS and baroreflex-mediated BP buffering, we set up a computer model of baroreflex BP control to simulate normal subjects and heart failure patients. Output variables for various randomly chosen combinations of feedback gains in the baroreflex arms were BP resonance, BP-buffering capacity, and BRS. Our results show that BP buffering and BP resonance are related expressions of baroreflex BP control and depend strongly on the sympathetic gain to the peripheral resistance. BRS is almost uniquely determined by the vagal baroreflex gain to the sinus node. In conclusion, BP buffering and BRS are unrelated unless coupled gains in all baroreflex limbs are assumed. Hence, the clinical benefit of a high BRS is most likely to be attributed to vagal effects on the heart instead of to effective BP buffering.
Preclinical Evaluation of Antiangiogenic Thrombospondin-1 Peptide Mimetics, ABT-526 and ABT-510, in Companion Dogs with Naturally Occurring Cancers
Authors: Rusk Anthony , McKeegan Evelyn , Haviv Fortuna , Majest Sandra , Henkin Jack , Khanna Chand
Published: December 2006

Purpose: The angiogenic phenotype of malignant cancers has been established as a target for cancer therapy. ABT-526 and ABT-510, two peptide mimetics of thrombospondin-1 (TSP-1), block angiogenesis in vitro and in vivo and slow tumor growth in mice. To guide the clinical development of these drugs, translational studies in dogs with naturally occurring cancers were initiated.

Experimental Design: A prospective open-label trial using ABT-510 or ABT-526 in pet dogs with measurable malignant spontaneously arising tumors. Endpoints included safety, pharmacokinetics, antitumor activity, and preliminary assessment of changes in circulating endothelial cell populations.

Results: Two-hundred and forty-two dogs were sequentially entered to this open-label trial. The elimination half-life for ABT-510 and ABT-526 was 0.7 and 0.8 h, respectively (range, 0.5-1 h). No dose-limiting toxicities were seen in any dogs (N = 242). Forty-two dogs receiving peptide had objective responses (>50% reduction in tumor size; n = 6) or significant disease stabilization. Most objective responses were seen after 60 days of exposure to the TSP-1 peptide. Antitumor activity was similar for both peptides and was seen in several histologies, including mammary carcinoma, head and neck carcinoma, soft tissue sarcoma, cutaneous T-cell lymphoma, and non–Hodgkin's lymphoma. Assessment of circulating endothelial cell populations in a small subset of dogs suggested that effective exposure to TSP-1 peptides may be associated with reductions in circulating endothelial cells.

Conclusions: These results support the safety and activity of ABT-526 and ABT-510 in dogs with naturally occurring malignant cancers. Data from this preclinical trial support the development of TSP-1 mimetic peptides as anticancer agents.
Cooperative Activity of Cytotoxic Chemotherapy with Antiangiogenic Thrombospondin-I Peptides, ABT-526 in Pet Dogs with Relapsed Lymphoma
Authors: Rusk Anthony , Cozzi Elizabeth , Stebbins Marty , Vail David , Graham Joanne , Valli Victor , Henkin Jack , Sharpee Rick , Khanna Chand
Published: December 2006

Purpose: Thrombospondin-I (TSP-I) is a natural antiangiogenic protein that enhances apoptosis of activated endothelial cells. A modified nonapeptide from TSP-I, ABT-526, has been found to be active in mouse cancer models and in dogs with naturally occurring cancers. To further assist in the development of ABT-526, we report herein on its evaluation in combination with cytotoxic chemotherapy in pet dogs with relapsed non-Hodgkin's lymphoma (NHL).

Experimental Design: Ninety-four pet dogs with naturally occurring first-relapse NHL were entered into a prospective randomized placebo controlled double-blinded trial of ABT-526 plus CeeNu (Bristol-Myers Squibb, New York, NY) versus CeeNu alone. Endpoints included response rate, duration of response, time to progression, and incidence of toxicoses.

Results: No significant ABT-526-specific toxicities were seen. CeeNu-associated toxicities, including neutropenia, thrombocytopenia, gastroenteritis, and elevated alanine transaminase, were similar. No significant difference in objective response rate was seen (ABT-526 + CeeNu versus placebo + CeeNu, 23/49 versus 23/37; P > 0.25). Cooperative activity between ABT-526 and CeeNu chemotherapy was evident based on a significant increase in the median response duration of dogs receiving ABT-526 plus CeeNu compared with placebo plus CeeNu (35 versus 15 days; P < 0.05). The time to progression for responding cases was also significantly greater in dogs receiving ABT-526 plus CeeNu compared with placebo plus CeeNu (41 versus 21 days; P < 0.05).

Conclusions: Results of this preclinical trial suggest that the activity of ABT-526 is sustained when combined with cytotoxic chemotherapy; furthermore, the activity seems to be associated with the maintenance of CeeNu-induced treatment responses. Further studies of TSP-I peptide antiangiogenic therapy in pet dogs and humans with NHL are warranted.
Epidermal Growth Factor Receptor Activation: How Exon 19 and 21 Mutations Changed Our Understanding of the Pathway
Authors: Rosell Rafael , Taron Miquel , Reguart Noemi , Isla Dolores , Moran Teresa
Published: December 2006

The discovery of epidermal growth factor receptor (EGFR) mutations in never-smokers has been the most relevant finding ever in non–small cell lung cancer. When patients whose tumors bear the sensitizing mutations are treated with the tyrosine kinase inhibitors gefitinib or erlotinib, we witness response rates and durations never before reported, including complete responses. At the same time, the presence of EGFR mutations has raised numerous new questions, tantalizing data, and new challenges for treatment. This is particularly true as we try to generalize the findings in lung cancer to other malignancies. The indiscriminate use of gefitinib or erlotinib in the general lung cancer population results in meager survival benefit for patients. Similarly, the tyrosine kinase inhibitors have limited activity in a variety of tumor types with EGFR overexpression. This has led to the question of whether EGFR remains a viable target in patients other than those whose tumors contain mutations, and whether the modest activity of cetuximab in colorectal cancer and head and neck cancer represents all that we can expect from inhibition of this pathway in the absence of mutation. Mechanisms of pathway activation other than mutation have been discovered in recent years, and include overexpression mediated by gene amplification or by amplification of a dinucleotide repeat in the EGFR promoter, mutation of an extracellular region on EGFR generating a mutant protein termed EGFRvIII, and enhanced signaling due to heterodimerization with other members of the EGFR family, particularly overexpression of HER2/HER3. The extent to which these paths to EGFR activation will confer sensitivity to the tyrosine kinase inhibitors or to EGFR monoclonal antibodies is being explored. Thus far, published clinical data suggest that there is little room for the administration of gefitinib or erlotinib in the absence of EGFR mutations. The five articles in this edition of CCR Focus will address the various mechanisms of EGFR pathway activation and provide insight into the potential for translation into clinical relevance.
The Coamplification Pattern of the MYCN Amplicon Is an Invariable Attribute of Most MYCN-Amplified Human Neuroblastomas
Authors: Weber Axel , Starke Sven , Bergmann Eckhard , Christiansen Holger
Published: December 2006

Purpose: Fifteen percent to 20% of human neuroblastomas show amplification of the MYCN oncogene physiologically located at chromosome 2p24-25, indicating an aggressive subtype of human neuroblastoma with a poor clinical outcome. Recent findings revealed that the structure of the amplicon differs interindividually and that coamplification of genes in telomeric proximity to MYCN might play a relevant role in neuroblastoma development and response to treatment, respectively. We now asked if the amplicon structure is an invariable attribute of an individual tumor or if the coamplification pattern could change during progress or in case of recurrent disease.

Experimental Design: We used a previously described multiplex PCR approach to analyze the coamplification status of MYCN-amplified human neuroblastomas (n = 33) in tumor tissue at the time of initial diagnosis and in consecutive tissue specimens at later time points after initial treatment or from relapsing disease. The MYCN copy number per haploid genome (Mcn/hg) in these specimens was determined in a separate duplex PCR.

Results: In 32 of the 33 investigated tumors, the amplicon structure showed no changes after initial chemotherapy and in recurrent disease. Mcn/hg showed a decrease after initial treatment (n = 23), whereas we found a significant increase in recurrent disease (n = 10).

Conclusion: Our data indicate that the initial determined structure of the 2p24-25 amplicon is a consistent attribute in the great majority of the individual MYCN-amplified neuroblastomas and shows no plasticity during or after chemotherapy. Observed changes in the Mcn/hg over the course of disease are in line with preexisting cell culture findings.
Sorafenib for the Treatment of Advanced Renal Cell Carcinoma
Authors: Kane Robert C. , Farrell Ann T. , Saber Haleh , Tang Shenghui , Williams Gene , Jee Josephine M. , Liang Chengyi , Booth Brian , Chidambaram Nallaperumal , Morse David , Sridhara Rajeshwari , Garvey Patricia , Justice Robert , Pazdur Richard
Published: December 2006

Purpose: This report describes the U.S. Food and Drug Administration (FDA) review and approval of sorafenib (Nexavar, BAY43-9006), a new small-molecule, oral, multi-kinase inhibitor for the treatment of patients with advanced renal cell carcinoma (RCC).

Experimental Design: After meeting with sponsors during development studies of sorafenib, the FDA reviewed the phase 3 protocol under the Special Protocol Assessment mechanism. Following new drug application submission, FDA independently analyzed the results of two studies in advanced RCC: a large, randomized, double-blinded, phase 3 international trial of single-agent sorafenib and a supportive phase 2 study.

Results: In the phase 3 trial, 902 patients with advanced progressive RCC after one prior systemic therapy were randomized to 400 mg sorafenib twice daily plus best supportive care or to a matching placebo plus best supportive care. Primary study end points included overall survival and progression-free survival (PFS). A PFS analysis, pre-specified and conducted after a total of 342 events, showed statistically significant superiority for the sorafenib group (median = 167 days) compared with that for the controls (median = 84 days, log-rank P < 0.000001); the sorafenib/placebo hazard ratio was 0.44 (95% confidence interval, 0.35-0.55). Results were similar regardless of patient risk score, performance status, age, or prior therapy. The (partial) response rate to sorafenib was 2.1%. Overall survival results are preliminary. The principal toxicities in the sorafenib patients included reversible skin rashes in 40% and hand-foot skin reaction in 30%; diarrhea was reported in 43%, treatment-emergent hypertension was reported in 17%, and sensory neuropathic changes were reported in 13%. Grade 4 adverse events were uncommon. Grade 3 adverse events were hand-foot skin reaction (6%), fatigue (5%), and hypertension (3%). Laboratory findings included asymptomatic hypophosphatemia in 45% of sorafenib patients versus 11% in the placebo arm and elevation of serum lipase in 41% of sorafenib patients versus 30% in the placebo arm. Grade 4 pancreatitis was reported in two sorafenib patients, although both patients subsequently resumed sorafenib, with one at full dose.

Conclusions: Sorafenib received FDA regular approval on December 20, 2005 for the treatment of advanced RCC based on the persuasive magnitude of improvement in PFS with acceptable safety. The recommended dose is 400 mg (two 200-mg tablets) twice daily taken either 1 h before or 2 h after meals. Adverse events were accommodated by temporary dose interruptions or reductions.
Methylation of Serum DNA Is an Independent Prognostic Marker in Colorectal Cancer
Authors: Wallner Maike , Herbst Andreas , Behrens Andrea , Crispin Alexander , Stieber Petra , Göke Burkhard , Lamerz Rolf , Kolligs Frank T.
Published: December 2006

Purpose: Aberrant CpG island hypermethylation is a feature of a subgroup of colorectal cancers, which can be detected in the serum of affected patients. This study was designed to identify methylation targets with prognostic significance in the serum of patients with colorectal cancer.

Experimental Design: In a gene evaluation set consisting of sera from 24 patients with local colorectal cancers, 14 with metastasized disease, and 20 healthy controls, the genes HPP1/TPEF, HLTF, and hMLH1 were identified as potential serum DNA methylation markers. These genes were further analyzed in a test set of sera of 104 patients with colorectal cancer.

Results: Methylation of HLTF, HPP1/TPEF, and hMLH1 was found to be significantly correlated with tumor size, and methylation of HLTF and HPP1/TPEF was significantly associated with metastatic disease and tumor stage. Moreover, methylation of HPP1/TPEF was also associated with serum carcinoembryonic antigen. The prognostic relevance of methylation of these genes was tested in pretherapeutic sera of 77 patients with known follow-up. Patients with methylation of HPP1/TPEF or HLTF were found to have unfavorable prognosis (P = 0.001 and 0.008). In contrast, serum methylation of hMLH1 was not associated with a higher risk of death. Multivariate analysis showed methylated HPP1 and/or HLTF serum DNA to be independently associated with poor outcome and a relative risk of death of 3.4 (95% confidence interval, 1.4-8.1; P = 0.007).

Conclusions: These data show that the methylation status of specific genes in the serum of patients with colorectal cancer has the potential to become a pretherapeutic predictor of outcome.
Amplification and Overexpression of CACNA1E Correlates with Relapse in Favorable Histology Wilms' Tumors
Authors: Natrajan Rachael , Little Suzanne E. , Reis-Filho Jorge S. , Hing Lara , Messahel Boo , Grundy Paul E. , Dome Jeffrey S. , Schneider Toni , Vujanic Gordan M. , Pritchard-Jones Kathy , Jones Chris
Published: December 2006

Purpose: The most well established molecular markers of poor outcome in Wilms' tumor are loss of heterozygosity at chromosomes 1p and/or 16q, although to date no specific genes at these loci have been identified. We have previously shown a link between genomic gain of chromosome 1q and tumor relapse and sought to further elucidate the role of genes on 1q in treatment failure.

Experimental Design: Microarray-based comparative genomic hybridization identified a microamplification harboring a single gene (CACNA1E) at 1q25.3 in 6 of 76 (7.9%) Wilms' tumors, correlating with a shorter relapse-free survival (P = 0.0044, log-rank test). Further characterization of this gene was carried out by measuring mRNA and protein expression as well as stable transfection of HEK293 cells.

Results: Overexpression of the CACNA1E transcript was associated with DNA copy number (P = 0.0204, ANOVA) and tumor relapse (P = 0.0851, log-rank test). Immunohistochemistry against the protein product CaV2.3 revealed expression localized to the apical membrane in the distal tubules of normal kidney but not to the metanephric blastemal cells of fetal kidney from which Wilms' tumors arise. Nuclear localization in 99 of 160 (61.9%) Wilms' tumor cases correlated with a reduced relapse-free survival, particularly in cases treated with preoperative chemotherapy (P = 0.009, log-rank test). Expression profiling of stably transfected HEK293 cells revealed specific up-regulation of the immediate early response genes EGR1/EGR2/EGR3 and FOS/FOSB, mediated by activation of the MEK/ERK5/Nur77 pathway.

Conclusions: These data identify a unique genetic aberration with direct clinical relevance in Wilms' tumor relapse and provide evidence for a potential novel mechanism of treatment resistance in these tumors.
β2-Microglobulin Promotes the Growth of Human Renal Cell Carcinoma through the Activation of the Protein Kinase A, Cyclic AMP–Responsive Element-Binding Protein, and Vascular Endothelial Growth Factor Axis
Authors: Nomura Takeo , Huang Wen-Chin , Zhau Haiyen E. , Wu Daqing , Xie Zhihui , Mimata Hiromitsu , Zayzafoon Majd , Young Andrew N. , Marshall Fray F. , Weitzmann M. Neale , Chung Leland W.K.
Published: December 2006

Purpose: β2-Microglobulin (β2M), a soluble protein secreted by cancer and host inflammatory cells, has various biological functions, including antigen presentation. Because aberrant expression of β2M has been reported in human renal cell carcinoma, we investigated the effects of β2M overexpression on cancer cell growth and analyzed its molecular signaling pathway.

Experimental Design: We established clonal cell lines that overexpressed β2M in human renal cell carcinoma (SN12C) cells and then examined cell growth in vitro and in vivo and studied the β2M-mediated downstream cell signaling pathway.

Results: Our results showed that β2M expression positively correlates with (a) in vitro growth on plastic dishes and as Matrigel colonies, (b) cell invasion and migration in Boyden chambers, and (c) vascular endothelial growth factor (VEGF) expression and secretion by cells. We found, in addition, that β2M mediates its action through increased phosphorylation of cyclic AMP–responsive element-binding protein (CREB) via the protein kinase A-CREB axis, resulting in increased VEGF expression and secretion. In convergence with this signal axis, β2M overexpression also activated both phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase pathways. β2M overexpression induced accelerated growth of SN12C in mouse subcutis and bone. Interrupting the β2M signaling pathway using small interfering RNA led to apoptosis with increased activation of caspase-3 and caspase-9 and cleaved poly(ADP-ribose) polymerase.

Conclusions: Our results showed for the first time that the β2M-protein kinase A-CREB-VEGF signaling axis plays a crucial role in support of renal cell carcinoma growth and progression and reveals a novel therapeutic target.
Effect of an Epidermal Growth Factor Receptor Inhibitor in Mouse Models of Lung Cancer
Authors: Yan Ying , Lu Yan , Wang Min , Vikis Haris , Yao Ruisheng , Wang Yian , Lubet Ronald A. , You Ming
Published: December 2006

Gefitinib (Iressa, ZD1839) is a potent high-affinity competitive tyrosine kinase inhibitor aimed primarily at epidermal growth factor receptor (EGFR). Inhibitors in this class have recently been approved for clinical use in the treatment of advanced non–small cell lung cancer as monotherapy following failure of chemotherapy. We examined the efficacy of gefitinib on lung tumorigenesis in mouse models using both postinitiation and progression protocols. Gefitinib was given at a dose of 200 mg/kg body weight (i.g.) beginning either 2 or 12 weeks following carcinogen initiation. In the postinitiation protocol, gefitinib significantly inhibited both tumor multiplicity (∼70%) and tumor load (∼90%) in A/J or p53-mutant mice (P < 0.0001). Interestingly, gefitinib was also highly effective against lung carcinogenesis in the progression protocol when individual animals already have multiple preinvasive lesions in the lung. Gefitinib exhibited ∼60% inhibition of tumor multiplicity and ∼80% inhibition of tumor load when compared with control mice (both P < 0.0001). These data show that gefitinib is a potent chemopreventive agent in both wild-type and p53-mutant mice and that a delayed administration was still highly effective. Analyses of mutations in the EGFR and K-ras genes in lung tumors from either control or treatment groups showed no mutations in EGFR and consistent mutation in K-ras. Using an oligonucleotide array on control and gefitinib-treated lesions showed that gefitinib treatment failed to alter the activity or the expression level of EGFR. In contrast, gefitinib treatment significantly altered the expression of a series of genes involved in cell cycle, cell proliferation, cell transformation, angiogenesis, DNA synthesis, cell migration, immune responses, and apoptosis. Thus, gefitinib showed highly promising chemopreventive and chemotherapeutic activity in this mouse model of lung carcinogenesis. (Mol Cancer Res 2006;4(12):971–81)
Attention Problems among Children with a Positive Family History of Alcohol Abuse or Dependence and Controls
Authors: Barnow Sven , Schuckit Marc , Smith Tom , Spitzer Carsten , Freyberger Harald-J.
Published: December 2006

This longitudinal study investigated the scope and course of attention problems over a period of time from preteen (ages 7–12 years) to early teen years (ages 13–17 years). We compared symptoms in subjects with and without a family history (FH) of alcohol abuse or dependence from among families without evidence of antisocial personality disorder. Evaluations of attention problems for the offspring were based on the Child Behavior Checklist and a validated semistructured interview carried out with the mother. The findings indicate no higher risk for attention problems and attention-deficit hyperactivity disorder (ADHD)-like symptoms in the children of families with an alcohol use disorder. Regarding the course of problems, the ADHD symptom count tended to decrease over time, especially for children without a FH of alcohol abuse or dependence. Further research will be needed to determine whether results can be replicated with families from different social strata and including subjects with the antisocial personality disorder.