bluuebunny/crossref_metadata_2025 huggingface dataset:
Drydock Service Life Cost Reduction by Use of Finite Element Analysis
Authors: ASHLEY ADAM R. , LAROCK FRANCIS J. , MANN CHARLES E.
Published: October 2008

Military Standard 1625 (SH) is currently the principal governing document for certification of floating drydocks which service US Navy ships. In order to maintain their certification, drydock owners must periodically document, evaluate, and repair corroded structural elements according to this standard's specifications. This evaluation and repair process is frequently cost‐prohibitive for some docks that have sustained significant corrosion. As an alternative, a finite element analysis (FEA) may be performed to isolate areas that require repair to maintain the safe operating capacity of the vessel. First, a finite element model of the drydock is created based on corrosion data from ultrasonic testing (UT). The corroded model is then analyzed to evaluate the global strength of the drydock and to isolate specific areas of corrosion that require repair. By isolating structurally critical areas, unnecessary repairs otherwise required, may be avoided. This process may result in considerable cost savings for drydock owners. In addition, wastage rates from historic ultrasonic survey data may be used to predict future corrosion. This paper will summarize the FEA conducted of the floating drydock ADEPT, a US Navy‐owned dock that is leased by Gulf Copper Ship Repair Inc. of Corpus Christi, TX. During the drydock's service life, significant corrosion has developed throughout the vessel's structure. Ultrasonic surveys were conducted to document the existing levels of corrosion and MAESTRO, a FEA program developed by Proteus Engineering, was used to develop a finite element model of the vessel based on the scantlings reported from the surveys. MAESTRO was then used to perform a FEA to isolate areas that require repair. Additionally, results from this analysis were used to calculate wastage rates and predict future corrosion. The FEA was then modified to analyze the future condition of the vessel in order to evaluate the need for future repairs.
Identification of Supplementary Metrics to Sustain Fleet Readiness from a Maintenance Perspective
Authors: DEAN ANTHONY W. , REINA JERRY J. , BAO HAN P.
Published: October 2008

A wide variety of programs and schemes are in place (and many programs are in continuous development by organizations such as the Office of Naval Research) that address the sustainability of the Navy's Fleet. Newly developed technologies are allowing for the continued design and development of much more complex ships with a host of innovative concepts and requirements. The cost of construction of these next‐generation ships, budgetary restraints, and other factors have also made it so necessary to maintain, adapt, and extend the life of the legacy fleet to meet operational requirements and maintain our maritime dominance. As we extend and adapt technology to become implemented across the wide variety of vessel platforms in existence in the legacy fleet, manning reductions are being implemented across the various ship‐type classes. As more and more maintenance is being shifted from the sailors on the ships to various off‐ship organizations, this brings into question the level of training necessary for ship's personnel in the maintenance area that is required when manning the ship from a tactical or operational perspective. Decision tools need to be developed for senior Navy management for use in evaluating and determining the optimal balance in manning ships from not only the operational perspective but also from the maintainability/survivability perspective. It is believed evaluation of the requirements, benchmarking, and the development of assessment metrics for determining the requirements of the Fleet for capable maintainers are of vital importance and will have far‐reaching impact on the Sea Warrior, Sea Trial, and Sea Enterprise programs in support of the “Sea Power 21” strategic concept of the Navy. This paper explores the necessity of benchmarking current ship's force capabilities, establishing manning requirement metrics, and evaluation of current maintenance policies.
Bond Strength and Etching Pattern of Adhesive Systems to Enamel: Effects of Conditioning Time and Enamel Preparation
Authors: PIVETTA MARCELA RIGUERA , MOURA SANDRA KISS , BARROSO LUCIA PEREIRA , LASCALA ANTONIO CARLOS , REIS ALESSANDRA , LOGUERCIO ALESSANDRO DOURADO , GRANDE ROSA HELENA MIRANDA
Published: October 2008

Statement of the problem:  The performance of self‐etch systems on enamel is controversial and seems to be dependent on the application technique and the enamel preparation.

Purpose of the Study:  To examine the effects of conditioning time and enamel surface preparation on bond strength and etching pattern of adhesive systems to enamel.

Materials and Methods:  Ninety‐six teeth were divided into 16 conditions (N = 6) in function of enamel preparation and conditioning time for bond strength test. The adhesive systems OptiBond FL (Kerr, Orange, CA, USA), OptiBond SOLO Plus (Kerr), Clearfil SE Bond (Kuraray, Osaka, Japan), and Adper Prompt L‐Pop (3M ESPE, St. Paul, MN, USA) were applied on unground or ground enamel following the manufacturers’ directions or doubling the conditioning time. Cylinders of Filtek Flow (0.5‐mm height) were applied to each bonded enamel surface using a Tygon tube (0.7 mm in diameter; Saint‐Gobain Corp., Aurora, OH, USA). After storage (24 h/37°C), the specimens were subjected to shear force (0.5 mm/min). The data were treated by a three‐way analysis of variance and Tukey's test (α = 0.05). The failure modes of the debonded interfaces and the etching pattern of adhesives were observed using scanning electron microscopy.

Results:  Only the main factor “adhesive” was statistically significant (p < 0.001). The lowest bond strength value was observed for OptiBond FL. The most defined etching pattern was observed for 35% phosphoric acid and for Adper Prompt L‐Pop. Mixed failures were observed for all adhesives, but OptiBond FL showed cohesive failures in resin predominantly.

Conclusions:  The increase in the conditioning time as well as the enamel pretreatment did not provide an increase in the resin–enamel bond strength values for the studied adhesives.

CLINICAL SIGNIFICANCE

The surface enamel preparation and the conditioning time do not affect the performance of self‐etch systems to enamel.
Hydrocolloid dressings in the management of acute wounds: a review of the literature
Authors: Thomas Stephen
Published: October 2008

A review of the literature suggests that the application of self‐adhesive hydrocolloid dressings, most commonly associated with the treatment of ulcerative conditions such as pressure ulcers and leg ulcers, may also offer benefits in the management of acute wounds of all types, for example decreasing healing times of donor sites by about 40% compared with traditional treatments. Healing times of superficial traumatic injuries and surgical wounds are similarly enhanced but in the treatment of burns, the principal benefit appears to be a reduction in wound pain, an effect that has also been reported in virtually all other wound types. The impermeable nature of hydrocolloids provides a protective covering to the wound, permitting washing or showering while helping to prevent the spread of pathogenic microorganisms. There also appear to be significant cost–benefits associated with the use of hydrocolloids. In recent years, hydrocolloid dressings have been replaced by other products such as foams for the treatment of more heavily exuding wounds but for more lightly exuding wounds they still offer many practical advantages and as such will undoubtedly continue to meet an important need in wound management practice.
Toward representative protection of the world's coasts and oceans—progress, gaps, and opportunities
Authors: Spalding Mark D. , Fish Lucy , Wood Louisa J.
Published: October 2008

Marine conservation lags behind terrestrial in the establishment of protected areas. This was recognized by the Convention on Biological Diversity, whose members, in 2004, agreed to establish “comprehensive, effectively managed, and ecologically representative” systems of marine protected areas (MPAs) by 2012. Halfway toward this target date, we look at the coverage of the world's 5045 MPAs from a biogeographic perspective. Only 4.09% of continental shelf areas are incorporated within MPAs, although coverage rises to 12.1% in a narrow coastal belt. Approximately half of all marine ecoregions have less than 1% MPA coverage across the shelf, but this is highly variable, and (8%) of ecoregions have >30% protection. Protection is greatest in the tropical realms, while temperate realms remain poorly represented. Given that that many sites lack effective management, even these low estimates of coverage are an optimistic measure of the extent of effective marine conservation.
Comparison of Extraintestinal Pathogenic
Escherichia coli
Strains from Human and Avian Sources Reveals a Mixed Subset Representing Potential Zoonotic Pathogens
Authors: Johnson Timothy J. , Wannemuehler Yvonne , Johnson Sara J. , Stell Adam L. , Doetkott Curt , Johnson James R. , Kim Kwang S. , Spanjaard Lodewijk , Nolan Lisa K.
Published: September 2008

Since extraintestinal pathogenic
Escherichia coli
(ExPEC) strains from human and avian hosts encounter similar challenges in establishing infection in extraintestinal locations, they may share similar contents of virulence genes and capacities to cause disease. In the present study, 1,074 ExPEC isolates were classified by phylogenetic group and possession of 67 other traits, including virulence-associated genes and plasmid replicon types. These ExPEC isolates included 452 avian pathogenic
E. coli
strains from avian colibacillosis, 91 neonatal meningitis
E. coli
(NMEC) strains causing human neonatal meningitis, and 531 uropathogenic
E. coli
strains from human urinary tract infections. Cluster analysis of the data revealed that most members of each subpathotype represent a genetically distinct group and have distinguishing characteristics. However, a genotyping cluster containing 108 ExPEC isolates was identified, heavily mixed with regard to subpathotype, in which there was substantial trait overlap. Many of the isolates within this cluster belonged to the O1, O2, or O18 serogroup. Also, 58% belonged to the ST95 multilocus sequence typing group, and over 90% of them were assigned to the B2 phylogenetic group typical of human ExPEC strains. This cluster contained strains with a high number of both chromosome- and plasmid-associated ExPEC genes. Further characterization of this ExPEC subset with zoonotic potential urges future studies exploring the potential for the transmission of certain ExPEC strains between humans and animals. Also, the widespread occurrence of plasmids among NMEC strains and members of the mixed cluster suggests that plasmid-mediated virulence in these pathotypes warrants further attention.
Biofilm Formation by
Pneumocystis
spp
Authors: Cushion Melanie T. , Collins Margaret S. , Linke Michael J.
Published: September 2008

Pneumocystis
spp. can cause a lethal pneumonia in hosts with debilitated immune systems. The manner in which these fungal infections spread throughout the lung, the life cycles of the organisms, and their strategies used for survival within the mammalian host are largely unknown, due in part to the lack of a continuous cultivation method. Biofilm formation is one strategy used by microbes for protection against environmental assaults, for communication and differentiation, and as foci for dissemination. We posited that the attachment and growth of
Pneumocystis
within the lung alveoli is akin to biofilm formation. An in vitro system comprised of insert wells suspended in multiwell plates containing supplemented RPMI 1640 medium supported biofilm formation by
P. carinii
(from rat) and
P. murina
(from mouse).Dramatic morphological changes accompanied the transition to a biofilm. Cyst and trophic forms became highly refractile and produced branching formations that anastomosed into large macroscopic clusters that spread across the insert. Confocal microscopy revealed stacking of viable organisms enmeshed in concanavalin A-staining extracellular matrix. Biofilms matured over a 3-week time period and could be passaged. These passaged organisms were able to cause infection in immunosuppressed rodents. Biofilm formation was inhibited by farnesol, a quorum-sensing molecule in
Candida
spp., suggesting that a similar communication system may be operational in the
Pneumocystis
biofilms. Intense staining with a monoclonal antibody to the major surface glycoproteins and an increase in (1,3)-β-
d
-glucan content suggest that these components contributed to the refractile properties. Identification of this biofilm process provides a tractable in vitro system that should fundamentally advance the study of
Pneumocystis
.
SETTLEMENT OF A HIGH EMBANKMENT AND OVERPASS STRUCTURES IN OTTAWA
Authors: Burn K. N.
Published: October 2008

Settlement observations have been conducted over a 5-year period on a 20-ft-high earth embankment and 2 highway overpass structures founded on spread footings over a thick deposit of Leda clay. The applied stresses were considerably less than the overconsolidation pressure of the clay. In the five years since construction, settlements of approximately 12 cm have occurred, of which about 4 cm occurred immediately. The observed settlements are compared with settlement predictions on the basis of various types of laboratory tests. The observations indicate that significant settlements occur on a long-term basis and can be attributed to a slow yielding of the clay structure. Piezometers failed to detect any excess pore water pressure due to slow process of consolidation.
Leptin inhibits food-deprivation-induced increases in food intake and food hoarding
Authors: Keen-Rhinehart Erin , Bartness Timothy J.
Published: October 2008

Food deprivation stimulates foraging and hoarding and to a much lesser extent, food intake in Siberian hamsters. Leptin, the anorexigenic hormone secreted primarily from adipocytes, may act in the periphery, the brain, or both to inhibit these ingestive behaviors. Therefore, we tested whether leptin given either intracerebroventricularly or intraperitoneally, would block food deprivation-induced increases in food hoarding, foraging, and intake in animals with differing foraging requirements. Hamsters were trained in a running wheel-based food delivery foraging system coupled with simulated burrow housing. We determined the effects of food deprivation and several peripheral doses of leptin on plasma leptin concentrations. Hamsters were then food deprived for 48 h and given leptin (0, 10, 40, or 80 μg ip), and additional hamsters were food deprived for 48 h and given leptin (0, 1.25, 2.5, or 5.0 μg icv). Foraging, food intake, and hoarding were measured postinjection. Food deprivation stimulated food hoarding to a greater degree and duration than food intake. In animals with a foraging requirement, intracerebroventricular leptin almost completely blocked food deprivation-induced increased food hoarding and intake, but increased foraging. Peripheral leptin treatment was most effective in a sedentary control group, completely inhibiting food deprivation-induced increased food hoarding and intake at the two highest doses, and did not affect foraging at any dose. Thus, the ability of leptin to inhibit food deprivation-induced increases in ingestive behaviors differs based on foraging effort (energy expenditure) and the route of administration of leptin administration.
Asymmetric Operation of the Locomotor Central Pattern Generator in the Neonatal Mouse Spinal Cord
Authors: Endo Toshiaki , Kiehn Ole
Published: October 2008

The rhythmic voltage oscillations in motor neurons (MNs) during locomotor movements reflect the operation of the pre-MN central pattern generator (CPG) network. Recordings from MNs can thus be used as a method to deduct the organization of CPGs. Here, we use continuous conductance measurements and decomposition methods to quantitatively assess the weighting and phase tuning of synaptic inputs to different flexor and extensor MNs during locomotor-like activity in the isolated neonatal mice lumbar spinal cord preparation. Whole cell recordings were obtained from 22 flexor and 18 extensor MNs in rostral and caudal lumbar segments. In all flexor and the large majority of extensor MNs the extracted excitatory and inhibitory synaptic conductances alternate but with a predominance of inhibitory conductances, most pronounced in extensors. These conductance changes are consistent with a “push–pull” operation of locomotor CPG. The extracted excitatory and inhibitory synaptic conductances varied between 2 and 56% of the mean total conductance. Analysis of the phase tuning of the extracted synaptic conductances in flexor and extensor MNs in the rostral lumbar cord showed that the flexor-phase–related synaptic conductance changes have sharper locomotor-phase tuning than the extensor-phase–related conductances, suggesting a modular organization of premotor CPG networks consisting of reciprocally coupled, but differently composed, flexor and extensor CPG networks. There was a clear difference between phase tuning in rostral and caudal MNs, suggesting a distinct operation of CPG networks in different lumbar segments. The highly asymmetric features were preserved throughout all ranges of locomotor frequencies investigated and with different combinations of locomotor-inducing drugs. The asymmetric nature of CPG operation and phase tuning of the conductance profiles provide important clues to the organization of the rodent locomotor CPG and are compatible with a multilayered and distributed structure of the network.
What Can Population Calcium Imaging Tell Us About Neural Circuits?
Authors: Kwan Alex C.
Published: October 2008

Calcium imaging of bulk-loaded fluorescent indicators can be used to record the spiking activity of hundreds of neurons. Recent advances promise imaging technologies that are faster, more efficient, and applicable to awake animals, thereby moving imaging capabilities closer to the traditional strengths of multi-electrode arrays. This article reviews these technical achievements and discusses how they can help us achieve the goal of understanding neural circuits.
Renal medullary 11β-hydroxysteroid dehydrogenase type 1 in Dahl salt-sensitive hypertension
Authors: Liu Yong , Singh Ravinder J. , Usa Kristie , Netzel Brian C. , Liang Mingyu
Published: October 2008

The Dahl salt-sensitive rat is a widely used model of human salt-sensitive forms of hypertension. The kidney plays an important role in the pathogenesis of Dahl salt-sensitive hypertension, but the molecular mechanisms involved remain a subject of intensive investigation. Gene expression profiling studies suggested that 11β-hydroxysteroid dehydrogenase type 1 might be dysregulated in the renal medulla of Dahl salt-sensitive rats. Additional analysis confirmed that renal medullary expression of 11β-hydroxysteroid dehydrogenase type 1 was downregulated by a high-salt diet in SS-13BN rats, a consomic rat strain with reduced blood pressure salt sensitivity, but not in Dahl salt-sensitive rats. 11β-Hydroxysteroid dehydrogenase type 1 is known to convert inactive 11-dehydrocorticosterone to active corticosterone. The urinary corticosterone/11-dehydrocorticosterone ratio as well as urinary excretion of corticosterone was higher in Dahl salt-sensitive rats than in SS-13BN rats. Knockdown of renal medullary 11β-hydroxysteroid dehydrogenase type 1 with small-interfering RNA attenuated the early phase of salt-induced hypertension in Dahl salt-sensitive rats and reduced urinary excretion of corticosterone. Knockdown of 11β-hydroxysteroid dehydrogenase type 1 did not affect blood pressure in SS-13BN rats. Long-term attenuation of salt-induced hypertension was achieved with small hairpin RNA targeting renal medullary 11β-hydroxysteroid dehydrogenase type 1. In summary, we have demonstrated that suppression of 11β-hydroxysteroid dehydrogenase type 1 expression in the renal medulla attenuates salt-induced hypertension in Dahl salt-sensitive rats.
Abnormal DNA Methylation ofCD133in Colorectal and Glioblastoma Tumors
Authors: Yi Joo Mi , Tsai Hsing-Chen , Glöckner Sabine C. , Lin Steven , Ohm Joyce E. , Easwaran Hari , James C. David , Costello Joseph F. , Riggins Gregory , Eberhart Charles G. , Laterra John , Vescovi Angelo L. , Ahuja Nita , Herman James G. , Schuebel Kornel E. , Baylin Stephen B.
Published: October 2008

Much recent effort has focused on identifying and characterizing cellular markers that distinguish tumor propagating cells (TPC) from more differentiated progeny. We report here an unusual promoter DNA methylation pattern for one such marker, the cell surface antigen CD133 (Prominin 1). This protein has been extensively used to enrich putative cancer propagating stem-like cell populations in epithelial tumors and, especially, glioblastomas. We find that, within individual cell lines of cultured colon cancers and glioblastomas, the promoter CpG island of CD133 is DNA methylated, primarily, in cells with absent or low expression of the marker protein, whereas lack of such methylation is evident in purely CD133+ cells. Differential histone modification marks of active versus repressed genes accompany these DNA methylation changes. This heterogeneous CpG island DNA methylation status in the tumors is unusual in that other DNA hypermethylated genes tested in such cultures preserve their methylation patterns between separated CD133+ and CD133− cell populations. Furthermore, the CD133 DNA methylation seems to constitute an abnormal promoter signature because it is not found in normal brain and colon but only in cultured and primary tumors. Thus, the DNA methylation is imposed on the transition between the active versus repressed transcription state for CD133 only in tumors. Our findings provide additional insight for the dynamics of aberrant DNA methylation associated with aberrant gene silencing in human tumors. [Cancer Res 2008;68(19):8094–103]
Ectopic Expression of P-Cadherin Correlates with Promoter Hypomethylation Early in Colorectal Carcinogenesis and Enhanced Intestinal Crypt Fission In vivo
Authors: Milicic Anita , Harrison Lea-Anne , Goodlad Robert A. , Hardy Robert G. , Nicholson Anna M. , Presz Michal , Sieber Oliver , Santander Sonia , Pringle James H. , Mandir Nikki , East Philip , Obszynska Jolanta , Sanders Scott , Piazuelo Elena , Shaw Jacqui , Harrison Rebecca , Tomlinson Ian P. , McDonald Stuart A.C. , Wright Nicholas A. , Jankowski Janusz A.Z.
Published: October 2008

P-cadherin is normally expressed in the basal layer of squamous epithelia and absent from the healthy intestine and colon. We have previously shown it to be expressed in all inflamed, hyperplastic, and dysplastic intestinal and colonic mucosa. This study aimed to better understand the mechanisms controlling the expression of P-cadherin and the biological effects of its ectopic presence in the intestine and colon. We investigated the CpG methylation status of the P-cadherin (CDH3) promoter and P-cadherin mRNA and protein expression in cases of familial and sporadic colorectal cancer (CRC). The CDH3 promoter was hypomethylated in colonic aberrant crypt foci, in CRC, and, occasionally, in the normal epithelium adjacent to cancer, demonstrating a potential “field effect” of cancerization. The hypomethylation was also associated with induction of P-cadherin expression in the neoplastic colon (P < 0.0001). We then created transgenic mice that overexpressed P-cadherin specifically in the intestinal and colonic epithelium under the liver fatty acid binding protein promoter. Forced ectopic expression of P-cadherin accompanied by indomethacin-induced inflammation resulted in a 3-fold higher crypt fission rate within the small and large intestines in the homozygous mice compared with the wild-type animals (P < 0.02). We conclude that epigenetic demethylation of the P-cadherin promoter in the human intestine permits its ectopic expression very early in the colorectal adenoma-carcinoma sequence and persists during invasive cancer. Induced P-cadherin expression, especially in mucosal damage, leads to an increased rate of crypt fission, a common feature of clonal expansion in gastrointestinal dysplasia. [Cancer Res 2008;68(19):7760–8]
Heterogeneity of Receptor Function in Colon Carcinoma Cells Determined by Cross-talk between Type I Insulin-like Growth Factor Receptor and Epidermal Growth Factor Receptor
Authors: Hu Yi Peter , Patil Sandip B. , Panasiewicz Michelle , Li Wenhui , Hauser Jennie , Humphrey Lisa E. , Brattain Michael G.
Published: October 2008

This study identifies a novel cross-talk paradigm between the type I insulin-like growth factor receptor (IGF1R) and epidermal growth factor receptor (EGFR) in colon cancer cells. IGF1R activation by ligand exposure in growth factor–deprived cells induces Akt activation in the FET, CBS, and GEO colon cancer cell lines. Investigation of IGF1R-mediated signaling pathways using small interfering RNA approaches indicated that, as expected, phosphatidylinositol 3′-kinase (PI3K) was activated by IGF1R. Mitogen-activated protein kinase (MAPK) activity as reflected by phospho-extracellular signal-regulated kinase (ERK) induction was not significantly activated until later times following release of these cells from growth factor deprivation stress. The appearance of phospho-ERK was proximal to EGFR activation. Treatment of cells with the PI3K inhibitor LY294002 before release from stress resulted in a concentration-dependent loss of EGFR activation, whereas treatment with the MAPK inhibitor PD98059 did not block EGFR activation, indicating that EGFR activation was downstream of the IGF1R/PI3K pathway. PD98059 inhibition of MAPK was associated with a concentration-dependent reduction in EGFR-mediated phospho-ERK. EGFR inhibitor blocked induction of phospho-ERK, showing that MAPK activity was a consequence of EGFR-mediated signaling. On the other hand, a small-molecule IGF1R inhibitor, PQIP, blocked Akt phosphorylation. The divergent signaling functions of IGF1R and EGFR suggested the potential for synergism by a combination of therapy directed at the two receptors. Combination treatment with PQIP and EGFR inhibitor Tarceva resulted in synergistic effects as indicated by combination index analysis in all three cell lines tested. [Cancer Res 2008;68(19):8004–13]
Tbx3 Represses E-Cadherin Expression and Enhances Melanoma Invasiveness
Authors: Rodriguez Mercedes , Aladowicz Ewa , Lanfrancone Luisa , Goding Colin R.
Published: October 2008

The T-box transcription factors Tbx2 and Tbx3 are overexpressed in many cancers and in melanoma promote proliferation by actively suppressing senescence. Whether they also contribute to tumor progression via other mechanisms is not known. Here, we identify a novel role for these factors, providing evidence that Tbx3, and potentially Tbx2, directly repress the expression of E-cadherin, a keratinocyte-melanoma adhesion molecule whose loss is required for the acquisition of an invasive phenotype. Overexpression of Tbx2 and Tbx3 in melanoma cells down-regulates endogenous E-cadherin expression, whereas depletion of Tbx3, but not Tbx2, increases E-cadherin mRNA and protein levels and decreases melanoma invasiveness in vitro. Consistent with these observations, in melanoma tissue, Tbx3 and E-cadherin expression are inversely correlated. Depletion of Tbx3 also leads to substantial up-regulation of Tbx2. The results suggest that Tbx2 and Tbx3 may play a dual role during the radial to vertical growth phase transition by both inhibiting senescence via repression of p21CIP1 expression, and enhancing melanoma invasiveness by decreasing E-cadherin levels. [Cancer Res 2008;68(19):7872–81]
Evaluation of Cancer Tests of 1,3-Butadiene Using Internal Dose, Genotoxic Potency, and a Multiplicative Risk Model
Authors: Fred Charlotta , Törnqvist Margareta , Granath Fredrik
Published: October 2008

In cancer tests with 1,3-butadiene (BD), the mouse is much more sensitive than the rat. This is considered to be related to the metabolism of BD to the epoxide metabolites, 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane, and 1,2-epoxy-3,4-butanediol. This study evaluates whether the large difference in outcome in cancer tests with BD could be predicted quantitatively on the basis of the concentration over time in blood (AUC) of the epoxide metabolites, their mutagenic potency, and a multiplicative cancer risk model, which has earlier been used for ionizing radiation. Published data on hemoglobin adduct levels from inhalation experiments with BD were used for the estimation of the AUC of the epoxide metabolites in the cancer tests. The estimated AUC of the epoxides were then weighed together to a total genotoxic dose, by using the relative genotoxic potency of the respective epoxide inferred from in vitro hprt mutation assays using EB as standard. The tumor incidences predicted with the risk model on the basis of the total genotoxic dose correlated well with the earlier observed tumor incidences in the cancer tests. The total genotoxic dose that leads to a doubling of the tumor incidences was estimated to be the same in both species, 9 to 10 mmol/L×h EB-equivalents. The study validates the applicability of the multiplicative cancer risk model to genotoxic chemicals. Furthermore, according to this evaluation, different epoxide metabolites are predominating cancer-initiating agents in the cancer tests with BD, the diepoxide in the mouse, and the monoepoxides in the rat. [Cancer Res 2008;68(19):8014–21]
CD8+ T-Cell Responses against Hemoglobin-β Prevent Solid Tumor Growth
Authors: Komita Hideo , Zhao Xi , Taylor Jennifer L. , Sparvero Louis J. , Amoscato Andrew A. , Alber Sean , Watkins Simon C. , Pardee Angela D. , Wesa Amy K. , Storkus Walter J.
Published: October 2008

Bone marrow–derived dendritic cells engineered using recombinant adenovirus to secrete high levels of IL-12p70 dramatically inhibited the growth of established CMS4 sarcomas in BALB/c mice after intratumoral administration. An analysis of splenic CD8+ T cells in regressor mice revealed a strong, complex reactivity pattern against high-performance liquid chromatography (HPLC)–resolved peptides isolated by acid elution from single-cell suspensions of surgically resected CMS4 lesions. Mass spectrometry analyses defined two major overlapping peptide species that derive from the murine hemoglobin-β (HBB) protein within the most stimulatory HPLC fractions. Although cultured CMS4 tumor cells failed to express HBB mRNA based on reverse transcription-PCR analyses, prophylactic vaccination of BALB/c mice with vaccines containing HBB peptides promoted specific CD8+ T-cell responses that protected mice against a subsequent challenge with CMS4 or unrelated syngeneic (HBBneg) tumors of divergent histology (sarcoma, carcinomas of the breast or colon). In situ imaging suggested that vaccines limit or destabilize tumor-associated vascular structures, potentially by promoting immunity against HBB+ vascular pericytes. Importantly, there were no untoward effects of vaccination with the HBB peptide on peripheral RBC numbers, RBC hemoglobin content, or vascular structures in the brain or eye. [Cancer Res 2008;68(19):8076–84]
Chromosomal Instability in Unirradiated Hemaopoietic Cells Induced by Macrophages Exposed In vivo to Ionizing Radiation
Authors: Lorimore Sally A. , Chrystal Jennifer A. , Robinson Joanne I. , Coates Philip J. , Wright Eric G.
Published: October 2008

The tumorigenic potential of ionizing radiation has conventionally been attributed to DNA damage in irradiated cells induced at the time of exposure. Recently, there have been an increasing number of reports of damage in unirradiated cells that are either neighbors or descendants of irradiated cells, respectively, regarded as bystander effects and genomic instability and collectively termed nontargeted effects. In this study, we show that descendants of normal murine hemaopoietic clonogenic stem cells exposed to bone marrow–conditioned medium derived from γ-irradiated mice exhibit chromosomal instability unlike the descendants of directly γ-irradiated cells. The instability is expressed in bone marrow cells of the radiation-induced acute myeloid leukemia (r-AML) susceptible strain (CBA/Ca) but not in mice resistant to r-AML (C57BL/6). Furthermore, crossgenetic experiments show the induction of the instability phenotype requires both the producer and responder cells to be of the susceptible CBA/Ca genotype. Macrophages are the source of the bystander signals, and the signaling mechanism involves tumor necrosis factor-α, nitric oxide, and superoxide. The findings show a genotype-dependent chromosomal instability phenotype induced by radiation-induced macrophage-mediated bystander signaling. As the majority of accidental, occupational, and therapeutic exposures to ionizing radiation are partial body exposures, the findings have implications for understanding the consequences of such exposure. [Cancer Res 2008;68(19):8122–6]
PIK3CA Cooperates with Other Phosphatidylinositol 3′-Kinase Pathway Mutations to Effect Oncogenic Transformation
Authors: Oda Katsutoshi , Okada Jennifer , Timmerman Luika , Rodriguez-Viciana Pablo , Stokoe David , Shoji Keiko , Taketani Yuji , Kuramoto Hiroyuki , Knight Zachary A. , Shokat Kevan M. , McCormick Frank
Published: October 2008

Mutations in genes functioning in different pathways frequently occur together in the same cancer, whereas mutations in the same pathway tend to be mutually exclusive. However, the majority of colon, breast, and endometrial cancers that possess mutations in PIK3CA, the catalytic subunit p110α of phosphatidylinositol 3′-kinase (PI3K), also possess mutations or alterations in genes upstream of PI3K such as Ras, ERBB2/ERBB3, or PTEN. PIK3CA mutations occur almost exclusively in invasive tumors, whereas upstream mutations occur as frequently in early-stage and late-stage tumors, suggesting that PIK3CA mutation is a late-stage event that may augment earlier activation of the PI3K pathway. Consistent with this, we find that levels of p-AKT (Ser473) induced by mutant Ras or knockdown of PTEN were dramatically increased by addition of mutant PIK3CA. Soft agar assays revealed that anchorage-independent growth induced by mutant Ras was greatly increased in the presence of mutant PIK3CA. In breast, colon, and endometrial cancers in which the PI3K pathway is activated by a combination of mutant PIK3CA and alterations in Ras, ERBB2/3, or PTEN, signaling to downstream elements such as Akt was mediated exclusively by the p110α isoform, rather than a combination of different PI3K isoforms. Our data therefore suggest that in tumors with co-occurring mutations in multiple components of the PI3K pathway, selective inhibition of the α isoform of p110 is an attractive therapeutic strategy, especially for late-stage tumors. [Cancer Res 2008;68(19):8127–36]
Nuclear Survivin Abrogates Multiple Cell Cycle Checkpoints and Enhances Viral Oncolysis
Authors: Connell Claire M. , Wheatley Sally P. , McNeish Iain A.
Published: October 2008

Survivin (BIRC5) promotes cell division and survival with roles as chromosomal passenger protein and inhibitor of apoptosis protein (IAP). It is overexpressed in many cancers and is associated with resistance to chemotherapy and radiation. Previously, we showed that expression of survivin within the nucleus of HeLa cells accelerates its degradation and blocks apoptosis inhibition without affecting localization during mitosis. Here, we have investigated the effects of survivin on cell cycle control and potential therapeutic consequences using HeLa and IGROV1 cells expressing wild-type and nuclear-targeted survivin. We show that overexpression of survivin, especially within the nucleus, increases control over G1-S checkpoint via increased nuclear accumulation of cyclin D and cyclin-dependent kinase 4 and subsequent pRb phosphorylation. We investigated the influence of survivin on the activity of the E1A CR2-deleted oncolytic adenovirus dl922-947, which depends critically on an aberrant G1-S checkpoint. Nuclear expression of survivin augments virus-induced S-phase induction and increases viral protein expression and overall viral replication. There is a consequent increase in antitumor activity both in vitro and in vivo. The increased dl922-947 activity is restricted to malignant cells and is not associated with induction of apoptosis, nor does it rely on the role of survivin as an IAP. In addition, we observe the appearance of a large ≥4N population coincident with multiple mitotic defects in dl922-947–infected cells, both of which are significantly increased by nuclear survivin. This indicates that adenoviral activity is facilitated by abrogation of multiple cell cycle checkpoints and can be enhanced by expression of survivin within the nucleus. [Cancer Res 2008;68(19):7923–31]
Validation of the p21-Activated Kinases as Targets for Inhibition in Neurofibromatosis Type 2
Authors: Yi Chunling , Wilker Erik W. , Yaffe Michael B. , Stemmer-Rachamimov Anat , Kissil Joseph L.
Published: October 2008

Neurofibromatosis type 2 (NF2) is a dominantly inherited cancer disorder caused by mutations at the NF2 gene locus. Merlin, the protein product of the NF2 gene, has been shown to negatively regulate Rac1 signaling by inhibiting its downstream effector kinases, the p21-activated kinases (Pak). Given the implication of Paks in tumorigenesis, it is plausible that merlin's tumor suppressive function might be mediated, at least in part, via inhibition of the Paks. We present data indicating this is indeed the case. First, analysis of primary schwannoma samples derived from NF2 patients showed that in a significant fraction of the tumors, the activity of Pak1 was highly elevated. Second, we used shRNAs to knockdown Pak1, 2, and 3 in NIH3T3 cells expressing a dominant-negative form of merlin, NF2BBA (NIH3T3/NF2BBA), and find that simultaneous knockdown of Pak1-3 in these cells significantly reduced their growth rates in vitro and inhibited their ability to form tumors in vivo. Finally, while attempting to silence Pak1 in rat schwannoma cells, we found that these cells were unable to tolerate long-term Pak1 inhibition and rapidly moved to restore Pak1 levels by shutting down Pak1 shRNA expression through a methylation-dependent mechanism. These data suggest that inhibiting Pak could be a beneficial approach for the development of therapeutics toward NF2. In addition, the finding that the shRNA-mediated Pak1 suppression was silenced rapidly by methylation raises questions about the future application of such technologies for the treatment of diseases such as cancer. [Cancer Res 2008;68(19):7932–7]
Breast Tumor Kinase Phosphorylates p190RhoGAP to Regulate Rho and Ras and Promote Breast Carcinoma Growth, Migration, and Invasion
Authors: Shen Che-Hung , Chen Hsin-Yi , Lin Ming-Shien , Li Fang-Yen , Chang Cheng-Chi , Kuo Min-Liang , Settleman Jeffrey , Chen Ruey-Hwa
Published: October 2008

Breast tumor kinase (Brk), an Src-like nonreceptor tyrosine kinase, is overexpressed in breast cancer and several other cancer types. Our previous study indicates that Brk promotes cell migration and tumor invasion by phosphorylating the focal adhesion protein paxillin. Here, we report the identification of p190RhoGAP-A (p190) as a Brk substrate. Brk phosphorylates p190 at the Y1105 residue both in vitro and in vivo, thereby promoting the association of p190 with p120RasGAP (p120). As a consequence, Brk stimulates p190 and attenuates p120 functions, leading to RhoA inactivation and Ras activation, respectively. In carcinoma cells expressing high levels of Brk, endogenous Brk functions as a key contributor to epidermal growth factor–induced p190 tyrosine phosphorylation. We present evidence showing that p190 phosphorylation plays essential roles in both migratory and proliferative effects of Brk. Furthermore, disruption of p190 phosphorylation–induced p190/p120 complex in breast cancer cells abolishes not only the abilities of Brk to regulate RhoA and Ras but also the stimulatory effects of Brk on proliferation, migration, invasion, transformation, and tumorigenicity. Together, our findings reveal a previously unknown function of Brk in regulating both RhoA and Ras by phosphorylating p190 and provide evidence for the crucial roles of this Brk-elicited signaling pathway in promoting breast malignancy. [Cancer Res 2008;68(19):7779–87]
Runx2 Transcriptional Activation of Indian Hedgehog and a Downstream Bone Metastatic Pathway in Breast Cancer Cells
Authors: Pratap Jitesh , Wixted John J. , Gaur Tripti , Zaidi Sayyed K. , Dobson Jason , Gokul Karthiga Devi , Hussain Sadiq , van Wijnen Andre J. , Stein Janet L. , Stein Gary S. , Lian Jane B.
Published: October 2008

Runx2, required for bone formation, is ectopically expressed in breast cancer cells. To address the mechanism by which Runx2 contributes to the osteolytic disease induced by MDA-MB-231 cells, we investigated the effect of Runx2 on key components of the “vicious cycle” of transforming growth factor β (TGFβ)-mediated tumor growth and osteolysis. We find that Runx2 directly up-regulates Indian Hedgehog (IHH) and colocalizes with Gli2, a Hedgehog signaling molecule. These events further activate parathyroid hormone-related protein (PTHrP). Furthermore, Runx2 directly regulates the TGFβ-induced PTHrP levels. A subnuclear targeting deficient mutant Runx2, which disrupts TGFβ-induced Runx2-Smad interactions, failed to induce IHH and downstream events. In addition, Runx2 knockdown in MDA-MB-231 inhibited IHH and PTHrP expression in the presence of TGFβ. In vivo blockade of the Runx2-IHH pathway in MDA-MB-231 cells by Runx2 short hairpin RNA inhibition prevented the osteolytic disease. Thus, our studies define a novel role of Runx2 in up-regulating the vicious cycle of metastatic bone disease, in addition to Runx2 regulation of genes related to progression of tumor metastasis. [Cancer Res 2008;68(19):7795–802]
SLITs Suppress Tumor Growth In vivo by Silencing Sdf1/Cxcr4 within Breast Epithelium
Authors: Marlow Rebecca , Strickland Phyllis , Lee Ji Shin , Wu Xinyan , PeBenito Milana , Binnewies Mikhail , Le Elizabeth K. , Moran Angel , Macias Hector , Cardiff Robert D. , Sukumar Saraswati , Hinck Lindsay
Published: October 2008

The genes encoding Slits and their Robo receptors are silenced in many types of cancer, including breast, suggesting a role for this signaling pathway in suppressing tumorigenesis. The molecular mechanism underlying these tumor-suppressive effects has not been delineated. Here, we show that loss of Slits, or their Robo1 receptor, in murine mammary gland or human breast carcinoma cells results in coordinate up-regulation of the Sdf1 and Cxcr4 signaling axis, specifically within mammary epithelium. This is accompanied by hyperplastic changes in cells and desmoplastic alterations in the surrounding stroma. A similar inverse correlation between Slit and Cxcr4 expression is identified in human breast tumor tissues. Furthermore, we show in a xenograft model that Slit overexpression down-regulates CXCR4 and dominantly suppresses tumor growth. These studies classify Slits as negative regulators of Sdf1 and Cxcr4 and identify a molecular signature in hyperplastic breast lesions that signifies inappropriate up-regulation of key prometastatic genes. [Cancer Res 2008;68(19):7819–27]
Suppression of Prostate Cancer Nodal and Systemic Metastasis by Blockade of the Lymphangiogenic Axis
Authors: Burton Jeremy B. , Priceman Saul J. , Sung James L. , Brakenhielm Ebba , An Dong Sung , Pytowski Bronislaw , Alitalo Kari , Wu Lily
Published: October 2008

Lymph node involvement denotes a poor outcome for patients with prostate cancer. Our group, along with others, has shown that initial tumor cell dissemination to regional lymph nodes via lymphatics also promotes systemic metastasis in mouse models. The aim of this study was to investigate the efficacy of suppressive therapies targeting either the angiogenic or lymphangiogenic axis in inhibiting regional lymph node and systemic metastasis in subcutaneous and orthotopic prostate tumor xenografts. Both androgen-dependent and more aggressive androgen-independent prostate tumors were used in our investigations. Interestingly, we observed that the threshold for dissemination is lower in the vascular-rich prostatic microenvironment compared with subcutaneously grafted tumors. Both vascular endothelial growth factor-C (VEGF-C) ligand trap (sVEGFR-3) and antibody directed against VEGFR-3 (mF4-31C1) significantly reduced tumor lymphangiogenesis and metastasis to regional lymph nodes and distal vital organs without influencing tumor growth. Conversely, angiogenic blockade by short hairpin RNA against VEGF or anti–VEGFR-2 antibody (DC101) reduced tumor blood vessel density, significantly delayed tumor growth, and reduced systemic metastasis, although it was ineffective in reducing lymphangiogenesis or nodal metastasis. Collectively, these data clarify the utility of vascular therapeutics in prostate tumor growth and metastasis, particularly in the context of the prostate microenvironment. Our findings highlight the importance of lymphangiogenic therapies in the control of regional lymph node and systemic metastasis. [Cancer Res 2008;68(19):7828–37] [Cancer Res 2008;68(19):7828–37]
Vitamin C Antagonizes the Cytotoxic Effects of Antineoplastic Drugs
Authors: Heaney Mark L. , Gardner Jeffrey R. , Karasavvas Nicos , Golde David W. , Scheinberg David A. , Smith Emily A. , O'Connor Owen A.
Published: October 2008

Vitamin C is an antioxidant vitamin that has been hypothesized to antagonize the effects of reactive oxygen species–generating antineoplastic drugs. The therapeutic efficacy of the widely used antineoplastic drugs doxorubicin, cisplatin, vincristine, methotrexate, and imatinib were compared in leukemia (K562) and lymphoma (RL) cell lines with and without pretreatment with dehydroascorbic acid, the commonly transported form of vitamin C. The effect of vitamin C on viability, clonogenicity, apoptosis, P-glycoprotein, reactive oxygen species (ROS), and mitochondrial membrane potential was determined. Pretreatment with vitamin C caused a dose-dependent attenuation of cytotoxicity, as measured by trypan blue exclusion and colony formation after treatment with all antineoplastic agents tested. Vitamin C given before doxorubicin treatment led to a substantial reduction of therapeutic efficacy in mice with RL cell–derived xenogeneic tumors. Vitamin C treatment led to a dose-dependent decrease in apoptosis in cells treated with the antineoplastic agents that was not due to up-regulation of P-glycoprotein or vitamin C retention modulated by antineoplastics. Vitamin C had only modest effects on intracellular ROS and a more general cytoprotective profile than N-acetylcysteine, suggesting a mechanism of action that is not mediated by ROS. All antineoplastic agents tested caused mitochondrial membrane depolarization that was inhibited by vitamin C. These findings indicate that vitamin C given before mechanistically dissimilar antineoplastic agents antagonizes therapeutic efficacy in a model of human hematopoietic cancers by preserving mitochondrial membrane potential. These results support the hypothesis that vitamin C supplementation during cancer treatment may detrimentally affect therapeutic response. [Cancer Res 2008;68(19):8031–8]