bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystal Structure of Poliovirus 3CD Protein: Virally Encoded Protease and Precursor to the RNA-Dependent RNA Polymerase
Authors: Marcotte Laura L. , Wass Amanda B. , Gohara David W. , Pathak Harsh B. , Arnold Jamie J. , Filman David J. , Cameron Craig E. , Hogle James M.
Published: January 2007

Poliovirus 3CD is a multifunctional protein that serves as a precursor to the protease 3C
pro
and the viral polymerase 3D
pol
and also plays a role in the control of viral replication. Although 3CD is a fully functional protease, it lacks polymerase activity. We have solved the crystal structures of 3CD at a 3.4-Å resolution and the G64S fidelity mutant of 3D
pol
at a 3.0-Å resolution. In the 3CD structure, the 3C and 3D domains are joined by a poorly ordered polypeptide linker, possibly to facilitate its cleavage, in an arrangement that precludes intramolecular proteolysis. The polymerase active site is intact in both the 3CD and the 3D
pol
G64S structures, despite the disruption of a network proposed to position key residues in the active site. Therefore, changes in molecular flexibility may be responsible for the differences in fidelity and polymerase activities. Extensive packing contacts between symmetry-related 3CD molecules and the approach of the 3C domain's N terminus to the VPg binding site suggest how 3D
pol
makes biologically relevant interactions with the 3C, 3CD, and 3BCD proteins that control the uridylylation of VPg during the initiation of viral replication. Indeed, mutations designed to disrupt these interfaces have pronounced effects on the uridylylation reaction in vitro.
Clinical Resistance to Enfuvirtide Does Not Affect Susceptibility ofHuman Immunodeficiency Virus Type 1 to Other Classes of Entry Inhibitors
Authors: Ray Neelanjana , Harrison Jessamina E. , Blackburn Leslie A. , Martin Jeffrey N. , Deeks Steven G. , Doms Robert W.
Published: January 2007

The clinical use of the human immunodeficiency virus (HIV) fusion inhibitor enfuvirtide (ENF) can select for drug-resistant HIV-1 strains bearing mutations in the HR1 region of the viral envelope (Env) protein. We analyzed the properties of multiple Env proteins isolated from five patients who experienced an initial decline in viral load after ENF therapy followed by subsequent rebound due to emergence of ENF-resistant HIV-1. Prior to ENF therapy, each patient harbored genetically and phenotypically diverse Env proteins that used CCR5 and/or CXCR4 to elicit membrane fusion. Coreceptor usage patterns of the Envs isolated from two patients underwent homogenization following ENF therapy, whereas in the other three patients, recombination appeared to allow the introduction of a single HR1 sequence with ENF resistance mutations into phenotypically distinct Env proteins. Analysis of individual Env clones also revealed that prior to ENF therapy, there was sometimes marked heterogeneity in the susceptibility of individual Env proteins to coreceptor inhibitors. After virologic failure, all Envs acquired resistance to ENF but exhibited no consistent change in their sensitivity to the fusion inhibitor T-1249 or to coreceptor inhibitors. In summary, using patient-derived Env proteins, we found that ENF failure was associated with emergence of high-level resistance to ENF due largely to mutations in HR1 but that susceptibility to other entry inhibitors was unaffected, that in these late-stage patients there was greater clonal variability to coreceptor than to fusion inhibitors, and that recombination events in vivo could sometimes restore Env genotypic and phenotypic heterogeneity by introducing drug-resistant gp41 sequences into heterologous gp120 backgrounds.
Spring-Loaded Heptad Repeat Residues Regulate the Expression and Activation of Paramyxovirus Fusion Protein
Authors: Luque Laura E. , Russell Charles J.
Published: January 2007

During viral entry, the paramyxovirus fusion (F) protein fuses the viral
envelope to a cellular membrane. Similar to other class I viral fusion
glycoproteins, the F protein has two heptad repeat regions (HRA and
HRB) that are important in membrane fusion and can be targeted by
antiviral inhibitors. Upon activation of the F protein, HRA refolds
from a spring-loaded, crumpled structure into a coiled coil that
inserts a hydrophobic fusion peptide into the target membrane and binds
to the HRB helices to form a fusogenic hairpin. To investigate how F
protein conformational changes are regulated, we mutated in the Sendai
virus F protein a highly conserved 10-residue sequence in HRA that
undergoes major structural changes during protein refolding. Nine of
the 15 mutations studied caused significant defects in F protein
expression, processing, and fusogenicity. Conversely, the remaining six
mutations enhanced the fusogenicity of the F protein, most likely by
helping spring the HRA coil. Two of the residues that were neither
located at “a” or “d” positions in the
heptad repeat nor conserved among the paramyxoviruses were key
regulators of the folding and fusion activity of the F protein, showing
that residues not expected to be important in coiled-coil formation may
play important roles in regulating membrane fusion. Overall, the data
support the hypothesis that regions in the F protein that undergo
dramatic changes in secondary and tertiary structure between the
prefusion and hairpin conformations regulate F protein expression and
activation.
Two Potentially Important Elements of the Hepatitis B Virus Large Envelope Protein Are Dispensable for the Infectivity of Hepatitis Delta Virus
Authors: Gudima Severin , Meier Anja , Dunbrack Roland , Taylor John , Bruss Volker
Published: January 2007

Previous studies have attempted to clarify the roles of the pre-S1 and pre-S2 domains of the large envelope protein of hepatitis B virus (HBV) in attachment and entry into susceptible cells. Difficulties arise in that these domains contain regions involved in the nucleocapsid assembly of HBV and overlapping with the coding regions of the viral polymerase and RNA sequences required for reverse transcription. Such difficulties can be circumvented with hepatitis delta virus (HDV), which needs the HBV large envelope protein only for infectivity. Thus, mutated HBV envelope proteins were examined for their effects on HDV infectivity. Changing the C-terminal region of pre-S1 critical for HBV assembly allowed the envelopment of HDV and had no effect on infectivity in primary human hepatocytes. Similarly, a deletion of the 12 amino acids of a putative translocation motif (TLM) in pre-S2 had no effect. Thus, these two regions are not necessary for HDV infectivity and, by inference, are not needed for HBV attachment and entry into susceptible cells.
The Ubiquitous Cellular Transcriptional Factor USF Targets the Varicella-Zoster Virus Open Reading Frame 10 Promoter and Determines Virulence in Human Skin Xenografts in SCIDhu Mice In Vivo
Authors: Che Xibing , Berarducci Barbara , Sommer Marvin , Ruyechan William T. , Arvin Ann M.
Published: January 2007

Varicella-zoster virus (VZV) open reading frame 10 (ORF10) is a determinant of virulence in SCIDhu skin xenografts but not in human T cells in vivo. In this analysis of the regulation of ORF10 transcription, we have identified four ORF10-related transcripts, including a major 1.3-kb RNA spanning ORF10 only and three other read-through transcripts. Rapid-amplification-of-cDNA-ends experiments indicated that the 1.3-kb transcript of ORF10 has single initiation and termination sites. In transient expression assays, the ORF10 promoter was strongly stimulated by the major VZV transactivator, IE62. Deletion analyses revealed approximate boundaries for the full ORF10 promoter activity between −75 and −45 and between +5 and −8, relative to the ORF10 transcription start site. The recombinant virus POKA10-Δpro, with the ORF10 promoter deletion, blocked transcription of ORF10 and also of ORF9A and ORF9 mRNAs, whereas expression of read-through ORF9A/9/10 and ORF9/10 transcripts was increased, compensating for the loss of the monocistronic mRNAs. The cellular factor USF bound specifically to its consensus site within the ORF10 promoter and was required for IE62 transactivation, whereas disrupting the predicted TATA boxes or Oct-1 binding elements had no effect. The USF binding site was disrupted in the recombinant virus, POKA10-proΔUSF, and no ORF10 protein was produced. Both ORF10 promoter mutants reduced VZV replication in SCIDhu skin xenografts. These observations provided further evidence of the contribution of the ORF10 protein to VZV pathogenesis in skin and demonstrated that VZV depends upon the cellular transcriptional factor USF to support its virulence in human skin in vivo.
WHERE DO GAMES OF INNOVATION COME FROM? EXPLAINING THE PERSISTENCE OF DYNAMIC INNOVATION PATTERNS
Authors: FLORICEL SERGHEI , DOUGHERTY DEBORAH
Published: January 2007

This paper contributes to explaining how and why distinct games of innovation emerge by suggesting that games are nested in innovation systems with persistent innovation dynamics. Dominant lifecycle models focus on how innovation systems transit from an effervescent stage, to product innovation, to process innovation, and so on. They propose specific mechanisms and limiting conditions that affect knowledge production and investment to explain these systematic transitions. Building on these models, we rethink the conditions and mechanisms of innovation to suggest that endogenous renewal cycles can re-create the knowledge and funding necessary to maintain innovation systems for long periods in one stage. We take steps towards developing a theoretical model of innovation dynamics that extends the applicability of lifecycle theories and unifies them with emerging views such as high-velocity innovation and hyper-competition. We also describe three possible types of endogenous renewal cycles, each sustaining a different level of knowledge dynamism and enabling different types of games of innovation.
THE POWER OF NON-CONTRACTUAL INNOVATION
Authors: OLLEROS F. XAVIER
Published: January 2007

Currently, all major IT and telecom firms are busy trying to stimulate non-contractual complementary developments around their own core competences and offerings. But little has been done to explain the logic, strengths, and weaknesses of non-contractual innovation. The literature on open-platform leadership recognises the importance of non-contractual innovation, but only within the limited confines of a normative approach based on two implicit assumptions: that a platform's core and periphery are sharply and easily differentiated and that platforms are always grown and orchestrated from a monolithic core. Through analysis of two cases of decentralised open innovation: the emergence of video rental stores and the emergence of desktop-publishing systems. I argue that these assumptions do not apply to all open platforms. I conclude that by forcing a hierarchical framework onto the analysis, the normative approach underplays the role of non-contractual innovation and turns a blind eye to the radically self-organised and unforeseeable nature of some platforms' success.
Regulation of TRP channel TRPM2 by the tyrosine phosphatase PTPL1
Authors: Zhang Wenyi , Tong Qin , Conrad Kathleen , Wozney Jocelyn , Cheung Joseph Y. , Miller Barbara A.
Published: January 2007

TRPM2, a member of the transient receptor potential (TRP) superfamily, is a Ca2+-permeable channel, which mediates susceptibility to cell death following activation by oxidative stress, TNFα, or β-amyloid peptide. We determined that TRPM2 is rapidly tyrosine phosphorylated after stimulation with H2O2 or TNFα. Inhibition of tyrosine phosphorylation with the tyrosine kinase inhibitors genistein or PP2 significantly reduced the increase in [Ca2+]i observed after H2O2 or TNFα treatment in TRPM2-expressing cells, suggesting that phosphorylation is important in TRPM2 activation. Utilizing a TransSignal PDZ domain array blot to identify proteins which interact with TRPM2, we identified PTPL1 as a potential binding protein. PTPL1 is a widely expressed tyrosine phosphatase, which has a role in cell survival and tumorigenesis. Immunoprecipitation and glutathione- S-transferase pull-down assays confirmed that TRPM2 and PTPL1 interact. To examine the ability of PTPL1 to modulate phosphorylation or activation of TRPM2, PTPL1 was coexpressed with TRPM2 in human embryonic kidney-293T cells. This resulted in significantly reduced TRPM2 tyrosine phosphorylation, and inhibited the rise in [Ca2+]i and the loss of cell viability, which follow H2O2 or TNFα treatment. Consistent with these findings, reduction in endogenous PTPL1 expression with small interfering RNA resulted in increased TRPM2 tyrosine phosphorylation, a significantly greater rise in [Ca2+]i following H2O2 treatment, and enhanced susceptibility to H2O2-induced cell death. Endogenous TRPM2 and PTPL1 was associated in U937-ecoR cells, confirming the physiological relevance of this interaction. These data demonstrate that tyrosine phosphorylation of TRPM2 is important in its activation and function and that inhibition of TRPM2 tyrosine phosphorylation reduces Ca2+ influx and protects cell viability. They also suggest that modulation of TRPM2 tyrosine phosphorylation is a mechanism through which PTPL1 may mediate resistance to cell death.
Endogenous substance P modulates human cardiovascular regulation at rest and during orthostatic load
Authors: Dzurik Matthew V. , Diedrich André , Black Bonnie , Paranjape Sachin Y. , Raj Satish R. , Byrne Daniel W. , Robertson David
Published: January 2007

Substance P (SP) is a peptide neurotransmitter identified in many central and peripheral neural pathways. Its precise role in human physiology has been difficult to elucidate. We used the selective neurokinin 1 (NK1) antagonist aprepitant as a pharmacological probe to determine the role of endogenous SP in human cardiovascular regulation. We performed a randomized, double-blind, placebo-controlled, crossover trial in healthy subjects. Blockade of endogenous NK1 receptors reduced resting muscle sympathetic activity 38% ( P = 0.002), reduced systemic vascular resistance by 25% ( P = 0.021), and increased cardiac index by 47% ( P = 0.006). This constellation of changes did not, however, alter either blood pressure or heart rate in the supine position. NK1 antagonism also raised orthostatic heart rate change by 38% ( P = 0.023), although during the incremental postural adjustment on the tilt table neither heart rate nor blood pressure was altered significantly. Despite a mildly attenuated vagal baroreflex with SP blockade, the depressor and pressor responses to nitroprusside and phenylephrine did not differ compared with placebo, suggesting other compensatory mechanisms. NK1 blockade manifests as a decrease in muscle sympathetic nerve activity and systemic vascular resistance. Our study suggests SP exerts a tonic enhancement of sympathetic outflow to some cardiovascular structures via its modulation of the NK1 receptor. Most likely, this ubiquitous neurotransmitter exerts effects at multiple sites that, in the aggregate, are relatively well compensated under many circumstances but may emerge with perturbations. This study is consistent with a role for SP afferents in supporting peripheral vascular resistance.
Control of Foot Trajectory in Walking Toddlers: Adaptation to Load Changes
Authors: Dominici Nadia , Ivanenko Yuri P. , Lacquaniti Francesco
Published: January 2007

On earth, body weight is an inherent constraint, and accordingly, load-regulating mechanisms play an important role in terrestrial locomotion. How do toddlers deal with the effects of their full body weight when faced with the task of independent upright locomotion for the first time? Here we studied the effect of load variation on walking in 12 toddlers during their first unsupported steps, 15 older children (1.3–5 yr), and 10 adults. To simulate various levels of body weight, an experimenter held the trunk of the subject with both hands and supplied an approximately constant vertical force during stepping on a force platform. During unsupported stepping, the shape of the foot path in toddlers (typically single-peak toe trajectory) was different from that of adults and older children (double-peak trajectory). In contrast to adults and older children, who showed only limited changes in kinematic coordination, the “reduced-gravity” condition considerably affected the shape of the foot path in toddlers: they tended to make a high lift and forward foot overshoot at the end of swing. In addition, stepping at high levels of body unloading was characterized by a significant change in the initial direction of foot motion during early swing. Intermediate walkers (1.5–5 mo after walking onset) showed only partial improvement in foot trajectory characteristics. The results suggest that, at the onset of walking, changes in vertical body loads are not compensated accurately by the kinematic controllers; compensation necessitates a few months of independent walking experience.
A Role for Short-Term Synaptic Facilitation and Depression in the Processing of Intensity Information in the Auditory Brain Stem
Authors: MacLeod K. M. , Horiuchi T. K. , Carr C. E.
Published: January 2007

The nature of the synaptic connection from the auditory nerve onto the cochlear nucleus neurons has a profound impact on how sound information is transmitted. Short-term synaptic plasticity, by dynamically modulating synaptic strength, filters information contained in the firing patterns. In the sound-localization circuits of the brain stem, the synapses of the timing pathway are characterized by strong short-term depression. We investigated the short-term synaptic plasticity of the inputs to the bird's cochlear nucleus angularis (NA), which encodes intensity information, by using chick embryonic brain slices and trains of electrical stimulation. These excitatory inputs expressed a mixture of short-term facilitation and depression, unlike those in the timing nuclei that only depressed. Facilitation and depression at NA synapses were balanced such that postsynaptic response amplitude was often maintained throughout the train at high firing rates (>100 Hz). The steady-state input rate relationship of the balanced synapses linearly conveyed rate information and therefore transmits intensity information encoded as a rate code in the nerve. A quantitative model of synaptic transmission could account for the plasticity by including facilitation of release (with a time constant of ∼40 ms), and a two-step recovery from depression (with one slow time constant of ∼8 s, and one fast time constant of ∼20 ms). A simulation using the model fit to NA synapses and auditory nerve spike trains from recordings in vivo confirmed that these synapses can convey intensity information contained in natural train inputs.
Responses of Olfactory Forebrain Units to Amino Acids in the Channel Catfish
Authors: Nikonov Alexander A. , Caprio John
Published: January 2007

A paucity of information exists concerning the processing of odorant information by single neurons in any vertebrate above the level of the olfactory bulb (OB). In this report, odorant specificity to four types of L-α-amino acids (neutral with long side-chains, neutral with short side-chains, basic and acidic), known biologically relevant odorants for teleosts, was determined for 217 spontaneously active forebrain (FB) neurons in the channel catfish. Group I FB units were identified that were excited by only one of four types of amino acids; no Group I unit was encountered that was excited by an acidic amino acid. The Group I FB units exhibited similar preferences as described previously for OB neurons, suggesting that no major modifications of olfactory information for at least some of these units occurred between the OB and FB. Evidence, however, for the convergence of odor information between the OB and FB was suggested by Group II FB units that exhibited a broader excitatory molecular receptive range (EMRR) than those of previously recorded types of OB units or the Group I FB units. Group II FB units were excited by both neutral and basic amino acids and a few also by acidic amino acids, EMRRs not observed previously in OB units. Stimulus-induced inhibition, likely for contrast enhancement, was also often observed for the many of the FB units encountered. The observed EMRRs of the FB units presently identified and those of the OB units previously studied are consistent with the ability of catfish to behaviorally discriminate these compounds.
Lumbar Bone Marrow Microcirculation Measurements from Dynamic Contrast-Enhanced Magnetic Resonance Imaging Is a Predictor of Event-Free Survival in Progressive Multiple Myeloma
Authors: Hillengass Jens , Wasser Klaus , Delorme Stefan , Kiessling Fabian , Zechmann Christian , Benner Axel , Kauczor Hans-Ulrich , Ho Anthony D. , Goldschmidt Hartmut , Moehler Thomas M.
Published: January 2007

Purpose: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with high temporal resolution enables the detection of microcirculation variables amplitude A and exchange rate constant kep. In this study, the prognostic value of the DCE-MRI variables for overall survival and event-free survival in patients with progressive multiple myeloma was investigated.

Experimental Design: Between 1999 and 2001, 65 patients with progressive or relapse of multiple myeloma requiring therapy were investigated with DCE-MRI of the lumbar spine before start of therapy. The contrast uptake was quantified using a two-compartment model with the output variables amplitude A and exchange rate constant kep reflecting bone marrow microcirculation. The estimated median follow-up was 56 months. Event-free survival and overall survival were investigated for DCE-MRI variables and for established prognosis variables (β2-microglobulin, lactate dehydrogenase, albumin, and age).

Results: Using a multivariate Cox regression model, β2-microglobulin and amplitude A of DCE-MRI were identified as statistically significant prognostic variable of event-free survival with Ps of 0.01 and 0.02, respectively. A statistical correlation of DCE-MRI variables with overall survival could not be found. The multivariate analysis of β2-microglobulin, age, lactate dehydrogenase, and albumin revealed β2-microglobulin as statistically significant prognostic factor for overall survival in this group of patients (P < 0.001).

Conclusions: This analysis identifies contrast-enhanced DCE-MRI variable amplitude A reflecting increased bone marrow microcirculation and angiogenesis as a novel and possibly useful prognostic factor in patients with multiple myeloma. Prospective studies are currently done to further investigate this functional variable for prognosis and stratification of myeloma patients.
Glucocorticoids Modulate Tumor Radiation Response through a Decrease in Tumor Oxygen Consumption
Authors: Crokart Nathalie , Jordan Bénédicte F. , Baudelet Christine , Cron Gregory O. , Hotton Julie , Radermacher Kim , Grégoire Vincent , Beghein Nelson , Martinive Philippe , Bouzin Caroline , Feron Olivier , Gallez Bernard
Published: January 2007

Purpose: We hypothesized that glucocorticoids may enhance tumor radiosensitivity by increasing tumor oxygenation (pO2) through inhibition of mitochondrial respiration.

Experimental Design: The effect of three glucocorticoids (hydrocortisone, dexamethasone, and prednisolone) on pO2 was studied in murine TLT liver tumors and FSaII fibrosarcomas. At the time of maximum pO2 (tmax, 30 min after administration), perfusion, oxygen consumption, and radiation sensitivity were studied. Local pO2 measurements were done using electron paramagnetic resonance. The oxygen consumption rate of tumor cells after in vivo glucocorticoid administration was measured using high-frequency electron paramagnetic resonance. Tumor perfusion and permeability measurements were assessed by dynamic contrast-enhanced magnetic resonance imaging.

Results: All glucocorticoids tested caused a rapid increase in pO2. At tmax, tumor perfusion decreased, indicating that the increase in pO2 was not caused by an increase in oxygen supply. Also at tmax, global oxygen consumption decreased. When irradiation (25 Gy) was applied at tmax, the tumor radiosensitivity was enhanced (regrowth delay increased by a factor of 1.7).

Conclusion: These results show the potential usefulness of the administration of glucocorticoids before irradiation.
Phase I Clinical Trial of STA-4783 in Combination with Paclitaxel in Patients with Refractory Solid Tumors
Authors: Berkenblit Anna , Eder Joseph P. , Ryan David P. , Seiden Michael V. , Tatsuta Noriaki , Sherman Matthew L. , Dahl Thomas A. , Dezube Bruce J. , Supko Jeffrey G.
Published: January 2007

Purpose: STA-4783 is a new compound that markedly enhances the therapeutic index of paclitaxel against human tumor xenograft models. A phase I clinical trial was undertaken to determine the maximum tolerated dose, toxicity profile, and pharmacokinetics of STA-4783 in combination with paclitaxel.

Experimental Design: Adults with refractory solid tumors concurrently received STA-4783 and paclitaxel as a 3-h i.v. infusion at starting doses of 44 and 135 mg/m2, respectively. After increasing paclitaxel to 175 mg/m2, the STA-4783 dose was escalated as permitted by dose-limiting toxicity during the first 21-day cycle.

Results: Thirty-five patients were treated with eight dose levels of STA-4783/paclitaxel. In patients receiving 175 mg/m2 paclitaxel, the incidence of severe toxicity increased with escalation of the STA-4783 dose above 263 mg/m2, and 438 mg/m2 was the maximum tolerated dose. All toxicities were typical of paclitaxel, with neutropenia, mucositis, and myalgia/arthralgia being dose limiting. Partial responses were achieved in one patient with Kaposi's sarcoma and another with ovarian cancer that progressed during prior treatment with paclitaxel. STA-4783 exhibited linear pharmacokinetics characterized by rapid elimination from plasma (biological half-life, 1.06 ± 0.24 h) and a low steady-state apparent volume of distribution (25.1 ± 8.1 L/m2). The total body clearance of paclitaxel decreased significantly with escalation of the STA-4783 dose.

Conclusions: The STA-4783/paclitaxel combination was well tolerated with a toxicity profile similar to single-agent paclitaxel. Enhanced systemic exposure to paclitaxel resulting from a dose-dependent interaction with STA-4783 was associated with increased toxicity. Objective responses in two heavily pretreated patients, both with taxane exposure, have encouraged further clinical evaluation of this regimen.
A Phase I Study of Pemetrexed, Carboplatin, and Concurrent Radiotherapy in Patients with Locally Advanced or Metastatic Non–Small Cell Lung or Esophageal Cancer
Authors: Seiwert Tanguy Y. , Connell Philip P. , Mauer Ann M. , Hoffman Philip C. , George Christopher M. , Szeto Livia , Salgia Ravi , Posther Katherine E. , Nguyen Binh , Haraf Daniel J. , Vokes Everett E.
Published: January 2007

Purpose: The primary objective of this phase I study was to determine the maximum tolerated dose for pemetrexed, alone and in combination with carboplatin, with concurrent radiotherapy.

Experimental Design: Patients with locally advanced or metastatic non–small cell lung cancer (NSCLC) or esophageal cancer were treated every 21 days for two cycles. Regimen 1 was pemetrexed (200-600 mg/m2); regimen 2 was pemetrexed (500 mg/m2) with escalating carboplatin doses (AUC = 4-6). Both regimens included concurrent radiation (40-66 Gy; palliative-intent doses were lower).

Results: Thirty patients (18 locally advanced and 12 metastatic with dominant local symptoms) were enrolled, with an Eastern Cooperative Oncology Group performance status of 0/1/2 (n = 8/21/1). All dose levels were tolerable for regimen 1 (n = 18: 15 NSCLC and 3 esophageal cancers) and regimen 2 (n = 12: all NSCLC). In regimen 1, one dose-limiting toxicity (grade 4 esophagitis/anorexia) occurred (500 mg/m2). Grade 3 neutropenia (3 of 18 patients) was the main hematologic toxicity. In regimen 2, one dose-limiting toxicity (grade 3 esophagitis) occurred (500 mg/m2; AUC = 6); grade 3/4 leukopenia (4 of 12 patients) was the main hematologic toxicity. Four complete responses (2 pathology proven) and eight partial responses were observed. When systemically active chemotherapy doses were reached, further dose escalation was discontinued, and a phase II dose-range was established (pemetrexed 500 mg/m2 and carboplatin AUC = 5-6).

Conclusions: The combination of pemetrexed (500 mg/m2) and carboplatin (AUC = 5 or 6) with concurrent radiation is well tolerated, allows for the administration of systemically active chemotherapy doses, and shows signs of activity. To further determine efficacy, safety profile, and optimal dosing, the Cancer and Leukemia Group B study 30407 is currently evaluating this regimen in patients with unresectable stage III NSCLC.
Phase I Study of the Farnesyltransferase Inhibitor Lonafarnib with Weekly Paclitaxel in Patients with Solid Tumors
Authors: Ready Neal E. , Lipton Alan , Zhu Yali , Statkevich Paul , Frank Emily , Curtis Dolores , Bukowski Ronald M.
Published: January 2007

Purpose: To establish the maximum tolerated dose of the farnesyltransferase inhibitor lonafarnib (Sarasar, Schering-Plough Corp., Kenilworth, NJ) in combination with weekly paclitaxel in patients with solid tumors. Tolerability, pharmacokinetics, safety, and dose-limiting toxicity were characterized.

Experimental Design: Patients were enrolled from January 2000 to May 2001. Lonafarnib was administered continuously orally twice daily at doses of 100, 125, and 150 mg in combination with paclitaxel at doses of 40, 60, or 80 mg/m2 i.v. over 1 h weekly in 28-day cycles in a phase I design. Plasma samples for determinations of lonafarnib and paclitaxel concentrations were collected at selected time points.

Results: Twenty-seven patients were enrolled. The maximum tolerated dose (the dose level below where dose-limiting toxicity occurred and the recommended phase II dose) was lonafarnib 125 mg/m2 twice daily and paclitaxel 80 mg/m2 weekly. Dose-limiting toxicity was neutropenia with or without fever, which occurred in two of three patients treated at the lonafarnib 150 mg twice daily dose level. Diarrhea was a common side effect of lonafarnib but usually was mild to moderate in severity and could be controlled with standard medication without lonafarnib dose adjustment. Other reported adverse events included nausea, vomiting, fatigue, and taste changes. These adverse events were neither more frequent nor more severe than would be expected with paclitaxel alone. There were no apparent pharmacokinetic interactions between weekly paclitaxel and continuous twice-daily lonafarnib.

Conclusions: The recommended dose of lonafarnib for phase II trials is 125 mg orally twice daily when combined with weekly paclitaxel 80 mg/m2. The dose-limiting toxicity was neutropenia.
Regulation of Hepatocyte Growth Factor Activator Inhibitor 2 by Hypoxia in Breast Cancer
Authors: Generali Daniele , Fox Stephen B. , Berruti Alfredo , Moore John W. , Brizzi Maria Pia , Patel Nilay , Allevi Giovanni , Bonardi Simone , Aguggini Sergio , Bersiga Alessandra , Campo Leticia , Dogliotti Luigi , Bottini Alberto , Harris Adrian L.
Published: January 2007

Purpose: To examine the in vitro regulation of hepatocyte growth factor activator inhibitor type 2 (HAI-2) in breast cancer cells and the in vivo predictive role for the efficacy of chemoendocrine primary therapy in patients with breast cancer.

Materials and Methods: HAI-2 regulation was studied in a panel of breast cancer cell lines comparing normoxia to hypoxia. The effect of HIF-1α RNAi on HAI-2 expression was evaluated in these cells. HAI-2 was examined in breast cancer using in situ hybridization and immunohistochemistry. The HAI-2 predictive role was assessed in T2-4 N0-1 breast cancers (n = 177) enrolled in a neoadjuvant randomized trial comparing epirubicin versus epirubicin + tamoxifen.

Results: HAI-2 mRNA and protein were regulated by hypoxia in the c-erbB2–positive cell lines, SKBR3 and BT474, and controlled by HIF-1α in these cells. Immunohistochemistry confirmed this profile with high expression of HAI-2 in c-erbB2–positive breast cancer. HAI-2 was correlated with T status (P < 0.004), node involvement (P = 0.01), and c-erbB2 expression (P = 0.05). HAI-2 also correlated with hypoxia markers such as carbonic anhydrase IX expression (P = 0.01) and HIF-1α. Additionally, high levels of HAI-2 were a significant predictor for poor clinical complete response to preoperative epirubicin in univariate (P = 0.01) and multivariate analyses (P = 0.016). No correlation with disease-free survival and survival was observed.

Conclusion: HAI-2 expression in breast cancer correlated with tumor aggressiveness in vivo. It is a HIF target in c-erbB2–positive cells and it is an independent negative predictive factor of efficacy of anthracycline therapy. The interaction of HAI-2 with the hepatocyte growth factor activation pathway may be a useful site for therapeutic intervention.
Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography Predicts Tumor Differentiation, P-glycoprotein Expression, and Outcome after Resection in Hepatocellular Carcinoma
Authors: Seo Satoru , Hatano Etsuro , Higashi Tatsuya , Hara Tadashi , Tada Masaharu , Tamaki Nobuyuki , Iwaisako Keiko , Ikai Iwao , Uemoto Shinji
Published: January 2007

Purpose: To investigate the diagnostic value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for prediction of tumor differentiation, P-glycoprotein (P-gp) expression, and outcome in hepatocellular carcinoma (HCC) patients.

Experimental Design: Seventy HCC patients who underwent curative resection were prospectively enrolled in the study. FDG-PET was done 2 weeks preoperatively, and the standardized uptake value (SUV) and the tumor to nontumor SUV ratio (TNR) were calculated from FDG uptake. Tumor differentiation and P-gp expression were examined with H&E and immunohistochemical staining, respectively.

Results: SUV and TNR were significantly higher in poorly differentiated HCCs than in well-differentiated (P = 0.001 and 0.002) and moderately differentiated HCCs (P < 0.0001 and P < 0.0001). The percentage P-gp–positive area was significantly higher in well-differentiated HCCs than in poorly differentiated (P < 0.0001) and moderately differentiated HCCs (P = 0.0001). Inverse correlations were found between SUV and P-gp expression (r = −0.44; P < 0.0001) and between TNR and P-gp expression (r = −0.47; P = 0.01). Forty-three (61.4%) patients had postoperative recurrence. The overall and disease-free survival rates in the high TNR (≥2.0) group were significantly lower than in the low TNR (<2.0) group (P = 0.0001 and 0.0002). In multivariate analysis, a high α-fetoprotein level (risk ratio, 5.46; P = 0.003; risk ratio, 8.78; P = 0.006) and high TNR (risk ratio, 1.3; P = 0.03; risk ratio, 1.6; P = 0.02) were independent predictors of postoperative recurrence and overall survival.

Conclusions: The results suggest that preoperative FDG-PET reflects tumor differentiation and P-gp expression and may be a good predictor of outcome in HCC.
Cyclin A Immunocytology as a Risk Stratification Tool for Barrett's Esophagus Surveillance
Authors: Lao-Sirieix Pierre , Lovat Laurence , Fitzgerald Rebecca C.
Published: January 2007

Purpose: Endoscopic surveillance of Barrett's esophagus (BE) by histopathologic biopsy assessment is suboptimal. A proliferation marker, minichromosome maintenance protein 2, has potential as a biomarker but lacks specificity. We hypothesized that cyclin A, which detects a proportion of proliferating cells, would be more specific. Because cytologic sampling has clinical advantages, we also evaluated the efficacy of cyclin A in endoscopic brushing samples.

Experimental Design: A cross-sectional cyclin A immunostaining study was done in 77 patients attending for BE surveillance and 17 patients undergoing evaluation of esophageal adenocarcinoma. The control tissues were as follows: 30 squamous esophagus, 20 gastric antrum, and 13 duodenum. A nested case-control study was done within the same surveillance cohort (16 progressors compared with 32 matched controls) to determine the relative risk for progression. Immunocytology was done for endoscopic brushings collected prospectively from 75 BE ± dysplasia and 33 esophageal adenocarcinomas.

Results: Surface expression of cyclin A in BE samples correlated with the degree of dysplasia (P = 0.016). In the case-control cohort, patients with biopsies expressing cyclin A at the surface were more likely to progress to adenocarcinoma than those who did not (odds ratio, 7.5; 95% confidence interval, 1.8-30.7). The sensitivity and specificity of cyclin A expression in brushings for the detection of high-grade dysplasia and cancer patients were 97.8% and 58.7%, respectively. The associated negative predictive value was 97.4%.

Conclusions: Cyclin A immunopositivity correlates with cancer risk. Application of this marker to endoscopic brushings could be used as a first step to identify BE patients with the highest risk of progression.
CHIR-124, a Novel Potent Inhibitor of Chk1, Potentiates the Cytotoxicity of Topoisomerase I PoisonsIn vitroandIn vivo
Authors: Tse Archie N. , Rendahl Katherine G. , Sheikh Tahir , Cheema Haider , Aardalen Kim , Embry Millicent , Ma Sylvia , Moler Edward J. , Ni Zhi Jie , Lopes de Menezes Daniel E. , Hibner Barbara , Gesner Thomas G. , Schwartz Gary K.
Published: January 2007

Purpose: Chk1 kinase is a critical regulator of both S and G2-M phase cell cycle checkpoints in response to DNA damage. This study aimed to evaluate the biochemical, cellular, and antitumor effects of a novel Chk1 inhibitor, CHIR124.

Experimental Design: CHIR-124 was evaluated for its ability to abrogate cell cycle checkpoints, to potentiate cytotoxicity, and to inhibit Chk1-mediated signaling induced by topoisomerase I poisons in human tumor cell line and xenograft models.

Results: CHIR-124 is a quinolone-based small molecule that is structurally unrelated to other known inhibitors of Chk1. It potently and selectively inhibits Chk1 in vitro (IC50 = 0.0003 μmol/L). CHIR-124 interacts synergistically with topoisomerase poisons (e.g., camptothecin or SN-38) in causing growth inhibition in several p53-mutant solid tumor cell lines as determined by isobologram or response surface analysis. CHIR-124 abrogates the SN-38–induced S and G2-M checkpoints and potentiates apoptosis in MDA-MD-435 breast cancer cells. The abrogation of the G2-M checkpoint and induction of apoptosis by CHIR-124 are enhanced by the loss of p53. We have also shown that CHIR-124 treatment can restore the level of cdc25A protein, which is normally targeted by Chk1 for degradation following DNA damage, indicating that Chk1 signaling is suppressed in the presence of CHIR-124. Finally, in an orthotopic breast cancer xenograft model, CHIR-124 potentiates the growth inhibitory effects of irinotecan by abrogating the G2-M checkpoint and increasing tumor apoptosis.

Conclusions: CHIR-124 is a novel and potent Chk1 inhibitor with promising antitumor activities when used in combination with topoisomerase I poisons.
Copper-67 Radioimmunotherapy and Growth Inhibition by Anti–L1-Cell Adhesion Molecule Monoclonal Antibodies in a Therapy Model of Ovarian Cancer Metastasis
Authors: Knogler Karin , Grünberg Jürgen , Zimmermann Kurt , Cohrs Susan , Honer Michael , Ametamey Simon , Altevogt Peter , Fogel Mina , Schubiger P. August , Novak-Hofer Ilse
Published: January 2007

Purpose: We examined the tumor-targeting and therapeutic effects of 67Cu-labeled single amino acid mutant forms of anti-L1 monoclonal antibody chCE7 in nude mice with orthotopically implanted SKOV3ip human ovarian carcinoma cells.

Experimental Design: For radioimmunotherapy, chCE7 antibodies with a mutation of histidine 310 to alanine (chCE7H310A) and a mutation of asparagine 297 to glutamine (chCE7agl) were generated to achieve more rapid blood clearance. Biodistributions of 67Cu-4-(1,4,8,11-tetraazacyclotetradec-1-yl)-methyl benzoic acid tetrachloride (CPTA)–labeled mutant antibodies were measured in nude mice bearing SKOV3ip human ovarian cancer metastases. The effects of single i.v. injections of 67Cu-chCE7agl alone on tumor reduction and survival were investigated. In addition, a combination of low-dose 67Cu-radioimmunotherapy with unlabeled anti-L1 antibody L1-11A on survival was investigated.

Results: 67Cu-CPTA-chCE7agl showed high (up to 49% ID/g) and persistent (up to 168 h) uptake in SKOV3ip metastases, with low levels in normal tissues. 67Cu-CPTA-chCE7H310A revealed a shorter half-life in the blood and a lower tumor uptake and retention. A single low dose of 4 MBq of 67Cu-chCE7agl reduced tumor growth but did not prolong survival significantly, whereas a single 10.5 MBq dose of 67Cu-chCE7agl reduced tumor growth and prolonged survival significantly. The combination of unlabeled monoclonal antibody L1-11A with a subtherapeutic dose of 67Cu-radioimmunotherapy also prolonged survival significantly.

Conclusion: The results show improved pharmacokinetics and biodistributions as well as the therapeutic effect of the 67Cu-labeled single amino acid mutant chCE7agl. Therapeutic data indicate, for the first time, the feasibility of combining anti–L1-directed growth inhibition and 67Cu-radioimmunotherapy, thereby increasing the efficiency of antibody treatment of metastatic ovarian carcinoma.
Centromere Protein H Is a Novel Prognostic Marker for Nasopharyngeal Carcinoma Progression and Overall Patient Survival
Authors: Liao Wen-Ting , Song Li-Bing , Zhang Hui-Zhong , Zhang Xing , Zhang Ling , Liu Wan-Li , Feng Yan , Guo Bao-Hong , Mai Hai-Qiang , Cao Su-Mei , Li Man-Zhi , Qin Hai-De , Zeng Yi-Xin , Zeng Mu-Sheng
Published: January 2007

Purpose: The aim of the present study was to analyze the expression of Centromere protein H (CENP-H), one of the fundamental components of the human active kinetochore, in nasopharyngeal carcinoma (NPC) and to correlate it with clinicopathologic data, including patient survival.

Experimental Design: Using reverse transcription-PCR and Western blot, we detected the expression of CENP-H in normal nasopharyngeal epithelial cells, immortalized nasopharyngeal epithelial cell lines, and NPC cell lines. Using immunohistochemistry, we analyzed CENP-H protein expression in 160 clinicopathologically characterized NPC cases. Statistical analyses were applied to test for prognostic and diagnostic associations.

Results: Reverse transcription-PCR and Western blot showed that the expression level of CENP-H was higher in NPC cell lines and in immortalized nasopharyngeal epithelial cells than in the normal nasopharyngeal epithelial cell line at both transcriptional and translational levels. By immunohistochemical analysis, we found that 76 of 160 (47.5%) paraffin-embedded archival NPC biopsies showed high expression of CENP-H. Statistical analysis showed that there was a significant difference of CENP-H expression in patients categorized according to clinical stage (P = 0.024) and T classification (P = 0.027). Patients with higher CENP-H expression had shorter overall survival time, whereas patients with lower CENP-H expression had better survival. A prognostic value of CENP-H was also found of the subgroup of N0-N1 tumor classification. Multivariate analysis showed that CENP-H expression was an independent prognostic indicator for patient's survival.

Conclusions: Our results suggest that CENP-H protein is a valuable marker of NPC progression. High CENP-H expression is associated with poor overall survival in NPC patients.
The Bcl-2 Family Protein Inhibitor, ABT-737, Has Substantial Antimyeloma Activity and Shows Synergistic Effect with Dexamethasone and Melphalan
Authors: Trudel Suzanne , Stewart A. Keith , Li Zhihua , Shu Yanjun , Liang Sheng-Ben , Trieu Young , Reece Donna , Paterson Josh , Wang Dingyan , Wen Xiao-Yan
Published: January 2007

Purpose: The aim of this study is to investigate the antimyeloma activity of a novel Bcl-2 family inhibitor, ABT-737, in preclinical treatment of multiple myeloma.

Experimental Design: The antimyeloma activity of ABT-737 was evaluated in cultured myeloma cell lines and patient myeloma samples, and in a xenograft mouse myeloma model. Drug combination therapy using ABT-737 with other commonly used myeloma drugs was also investigated.

Results: MY5 and JJN3 cell lines exhibited the most sensitivity to ABT-737 with an EC50 of 0.2 and 0.5 μmol/L, respectively, with increased cell apoptosis and elevated activated caspase-3. We identified two distinct groups of myeloma patient samples that were either sensitive or resistant to the drug. Four of 15 patient bone marrow samples (27%) were highly sensitive to ABT-737 at doses of 0.25 and 0.5 μmol/L, which eliminated 80% to 90% of myeloma cells as a result of cellular apoptosis 3 days after drug treatment. ABT-737 showed a synergistic effect when combined with dexamethasone or melphalan in inducing myeloma cell death. Furthermore, the dexamethasone-resistant MM1(Dex)R myeloma cell line was highly sensitive to 0.2 μmol/L ABT-737. As determined by colony assay, little or no detectable toxicity to patient hematologic progenitor cells was observed at 1 μmol/L ABT-737. ABT-737 dose dependently suppressed tumor growth in a xenograft MY5 mouse model.

Conclusions: These studies show substantial antimyeloma activity of ABT-737 as a single agent or in combination with dexamethasone or melphalan and suggest a rationale for future clinical trials.
A Phase I and Pharmacokinetic Study of Pemetrexed Plus Irinotecan in Patients with Advanced Solid Malignancies
Authors: Rowinsky Eric K. , Beeram Muralidhar , Hammond Lisa A. , Schwartz Garry , De Bono Johann , Forouzesh Baharam , Chu Quincy , Latz Jane E. , Hong Shengyan , John William , Nguyen Binh
Published: January 2007

Purpose: The main objectives of this phase I and pharmacokinetic, open-label study were to characterize the principal toxicities and determine the maximum tolerated dose of the multitargeted antifolate pemetrexed administered in combination with irinotecan. The study also sought to detect major pharmacokinetic drug-drug interactions between these agents and preliminary evidence of antitumor activity in patients with advanced solid malignancies.

Experimental Design: Pemetrexed was administered as a 10-min i.v. infusion followed by irinotecan given i.v. over 90 min every 3 weeks to patients with advanced solid malignancies. The study objectives were first pursued in heavily pretreated patients and then in lightly pretreated patients who also received vitamin supplementation.

Results: Twenty-three heavily pretreated patients enrolled in the first stage of the study, and the maximum tolerated dose level of pemetrexed/irinotecan without vitamin supplementation was 400/250 mg/m2; further dose escalation was precluded by severe neutropenia that was protracted and/or associated with fever. In the second stage of the study, 28 lightly pretreated patients were administered pemetrexed/irinotecan with vitamin supplementation; these patients tolerated pemetrexed/irinotecan at a dose level of 500/350 mg/m2, which reflected clinically relevant single-agent doses of both agents. No major pharmacokinetic interactions between the agents were evident. Four patients, two patients each with colorectal cancer refractory to fluoropyrimidines and advanced mesothelioma, had partial responses.

Conclusions: The pemetrexed/irinotecan regimen is well tolerated in patients with advanced solid malignancies at clinically relevant single-agent doses. The recommended dose level of pemetrexed/irinotecan for subsequent disease-directed evaluations involving lightly pretreated patients is 500/350 mg/m2 every 3 weeks with vitamin supplementation.