bluuebunny/crossref_metadata_2025 huggingface dataset:
Gene deletion of P2Y4 receptor lowers exercise capacity and reduces myocardial hypertrophy with swimming exercise
Authors: Horckmans Michael , Léon-Gómez Elvira , Robaye Bernard , Balligand Jean-Luc , Boeynaems Jean-Marie , Dessy Chantal , Communi Didier
Published: August 2012

Nucleotides released within the heart under pathological conditions can be involved in cardioprotection or cardiac fibrosis through the activation purinergic P2Y2 and P2Y6 receptors, respectively. We previously demonstrated that adult P2Y4-null mice display a microcardia phenotype related to a cardiac angiogenic defect. To evaluate the functional consequences of this defect, we performed here a combination of cardiac monitoring and exercise tests. We investigated the exercise capacity of P2Y4 wild-type and P2Y4-null mice in forced swimming and running tests. Analysis of their stress, locomotion, and resignation was realized in open field, black and white box, and tail suspension experiments. Exercise-induced cardiac hypertrophy was evaluated after repeated and prolonged exercise in P2Y4 wild-type and P2Y4-null hearts. We showed that P2Y4-null mice have a lower exercise capacity in both swimming and treadmill tests. This was not related to decreased motivation or increased stress, since open field, white and black box, and mouse tail suspension tests gave comparable results in P2Y4 wild-type and P2Y4-null mice. Heart rate and blood pressure rose normally in P2Y4-null swimming mice equipped with a telemetric implant. On the contrary, we observed a delayed recovery of postexercise blood pressure after exercise in P2Y4-null mice. The heart rate increment in response to catecholamines was also similar in P2Y4 wild-type and P2Y4-null implanted mice, which is consistent with a similar level of cardiac β-receptor expression. Interestingly, the heart of P2Y4-null mice displayed a reduced sympathetic innervation associated with a decreased norepinephrine level. We also demonstrated that exercise-induced cardiac hypertrophy was lower in P2Y4-null mice after repeated and prolonged exercise. This was associated with a lower increase in cardiomyocyte size and microvessel density. In conclusion, besides its role in cardiac development, P2Y4 receptor could constitute an important regulator of acute and chronic response to exercise.
Independent and interactive effects of preload and afterload on the pump function of the isolated lymphangion
Authors: Scallan Joshua P. , Wolpers John H. , Muthuchamy Mariappan , Zawieja David C. , Gashev Anatoliy A. , Davis Michael J.
Published: August 2012

We tested the responses of single, isolated lymphangions to selective changes in preload and the effects of changing preload on the response to an imposed afterload. The methods used were similar to those described in our companion paper. Step-wise increases in input pressure (Pin; preload) over a pressure range between 0.5 and 3 cmH2O, at constant output pressure (Pout), led to increases in end-diastolic diameter, decreases in end-systolic diameter, and increases in stroke volume. From a baseline of 1 cmH2O, Pin elevation by 2–7 cmH2O consistently produced an immediate fall in stroke volume that subsequently recovered over a time course of 2–3 min. Surprisingly, this adaptation was associated with an increase in the slope of the end-systolic pressure-volume relationship, indicative of an increase in contractility. Lymphangions subjected to Pout levels exceeding their initial ejection limit would often accommodate by increasing diastolic filling to strengthen contraction sufficiently to match Pout. The lymphangion adaptation to various pressure combinations (Pin ramps with low or high levels of Pout, Pout ramps at low or intermediate levels of Pin, and combined Pin + Pout ramps) were analyzed using pressure-volume data to calculate stroke work. Under relatively low imposed loads, stroke work was maximal at low preloads (Pin ∼2 cmH2O), whereas at more elevated afterloads, the optimal preload for maximal work displayed a broad plateau over a Pin range of 5–11 cmH2O. These results provide new insights into the normal operation of the lymphatic pump, its comparison with the cardiac pump, and its potential capacity to adapt to increased loads during edemagenic and/or gravitational stress.
NOX2 (gp91phox) is a predominant O2 sensor in a human airway chemoreceptor cell line: biochemical, molecular, and electrophysiological evidence
Authors: Buttigieg Josef , Pan Jie , Yeger Herman , Cutz Ernest
Published: August 2012

Pulmonary neuroepithelial bodies (NEBs), composed of clusters of amine [serotonin (5-HT)] and peptide-producing cells, are widely distributed within the airway mucosa of human and animal lungs. NEBs are thought to function as airway O2-sensors, since they are extensively innervated and release 5-HT upon hypoxia exposure. The small cell lung carcinoma cell line (H146) provides a useful model for native NEBs, since they contain (and secrete) 5-HT and share the expression of a membrane-delimited O2 sensor [classical NADPH oxidase (NOX2) coupled to an O2-sensitive K+ channel]. In addition, both native NEBs and H146 cells express different NADPH oxidase homologs (NOX1, NOX4) and its subunits together with a variety of O2-sensitive voltage-dependent K+ channel proteins (Kv) and tandem pore acid-sensing K+ channels (TASK). Here we used H146 cells to investigate the role and interactions of various NADPH oxidase components in O2-sensing using a combination of coimmunoprecipitation, Western blot analysis (quantum dot labeling), and electrophysiology (patchclamp, amperometry) methods. Coimmunoprecipitation studies demonstrated formation of molecular complexes between NOX2 and Kv3.3 and Kv4.3 ion channels but not with TASK1 ion channels, while NOX4 associated with TASK1 but not with Kv channel proteins. Downregulation of mRNA for NOX2, but not for NOX4, suppressed hypoxia-sensitive outward current and significantly reduced hypoxia -induced 5-HT release. Collectively, our studies suggest that NOX2/Kv complexes are the predominant O2 sensor in H146 cells and, by inference, in native NEBs. Present findings favor a NEB cell-specific plasma membrane model of O2-sensing and suggest that unique NOX/K+ channel combinations may serve diverse physiological functions.
STAT6 regulates natural helper cell proliferation during lung inflammation initiated byAlternaria
Authors: Doherty Taylor A. , Khorram Naseem , Chang Jinny E. , Kim Hee-Kyoo , Rosenthal Peter , Croft Michael , Broide David H.
Published: August 2012

Asthma exacerbations can be caused by a number of factors, including the fungal allergen Alternaria, which is specifically associated with severe and near-fatal attacks. The mechanisms that trigger lung responses are unclear and might vary between allergens. A comparison between Alternaria, Aspergillus, Candida, and house dust mite, all allergens in humans, showed that only Alternaria promoted immediate innate airway eosinophilia within 12 h of inhalation in nonsensitized mice. Alternaria, but not the other allergens, induced a rapid increase in airway levels of IL-33, accompanied by IL-33 receptor (IL-33R)-positive natural helper cell (NHC) production of IL-5 and IL-13. NHCs in the lung and bone marrow constitutively expressed transcription factors [GATA-3 and E26 transformation-specific sequence-1 (ETS-1)] that could allow for rapid induction of T helper type 2 (Th2) cytokines. Lung NHC numbers and proliferation (%Ki-67), but not IL-5 or GATA-3 expression, were significantly reduced in STAT6-deficient mice 3 days after one challenge with Alternaria. Alternaria induced NHC expression of the EGF receptor ligand amphiregulin (partially dependent on STAT6), as well as EGF receptor signaling in the airway epithelium. Finally, human peripheral blood NHCs (CRTH2+CD127+lineage-negative lymphocytes) from allergic individuals highly expressed GATA-3 and ETS-1, similar to lung NHCs in mice. In summary, Alternaria-induced lung NHC proliferation and expression of amphiregulin are regulated by STAT6. In addition, NHCs in mouse and humans are primed to express Th2 cytokines through constitutive expression of GATA-3 and ETS-1. Thus several transcription factor pathways (STAT6, GATA-3, and ETS-1) may contribute to NHC proliferation and Th2-type responses in Alternaria-induced asthma.
Pathogenetic and predictive value of biomarkers in patients with ALI and lower severity of illness: results from two clinical trials
Authors: Agrawal Ashish , Zhuo Hanjing , Brady Sandra , Levitt Joseph , Steingrub Jay , Siegel Mark D. , Soto Graciela , Peterson Michael W. , Chesnutt Mark S. , Matthay Michael A. , Liu Kathleen D.
Published: August 2012

Plasma and bronchoalveolar lavage (BAL) biomarkers related to the pathogenesis of acute lung injury (ALI) have previously been associated with poorer clinical outcomes and increased disease severity among patients with ALI. Whether these biomarkers have predictive value in a less severely ill population that excludes septic patients with high APACHE II scores is currently unknown. We tested the association of plasma and BAL biomarkers with physiological markers of ALI severity or clinically relevant outcomes in a secondary analysis of a clinical trial of activated protein C for the treatment of ALI. Plasma plasminogen activator inhibitor-1 (PAI-1) and mini-BAL protein were both significantly associated with increased oxygenation index ( P = 0.02 and 0.01, respectively), whereas there was a trend toward an association between IL-6 and oxygenation index ( P = 0.057). High plasma IL-6, thrombomodulin, and mini-BAL protein were all significantly associated with fewer ventilator-free days (VFDs) ( P = 0.01, 0.01, and 0.05, respectively); no markers were associated with mortality, but we hypothesized that this was due to the small size of our cohort and the low death rate. To confirm these associations in a larger sample, we identified a restricted cohort of patients from the ARDS Network ALVEOLI study with similar baseline characteristics. We retested the associations of the significant biomarkers with markers of severity and clinical outcomes and studied IL-8 as an additional biomarker given its important predictive value in prior studies. In this restricted cohort, IL-6 was significantly associated with oxygenation index ( P = 0.02). Both IL-6 and IL-8 were associated with decreased VFDs and increased 28-day mortality. Future studies should be focused on examining larger numbers of patients with less severe ALI to further test the relative predictive value of plasma and mini-BAL biomarkers for clinically relevant outcomes, including VFDs and mortality, and for their prospective utility in risk stratification for future clinical trials.
Muscarinic receptor stimulation augments TGF-β1-induced contractile protein expression by airway smooth muscle cells
Authors: Oenema Tjitske A. , Smit Marieke , Smedinga Lyanne , Racké Kurt , Halayko Andrew J. , Meurs Herman , Gosens Reinoud
Published: August 2012

Acetylcholine (ACh) is the primary parasympathetic neurotransmitter in the airways. Recently, it was established that ACh, via muscarinic receptors, regulates airway remodeling in animal models of asthma and chronic obstructive pulmonary disease (COPD). The mechanisms involved are not well understood. Here, we investigated the functional interaction between muscarinic receptor stimulation and transforming growth factor (TGF)-β1 on the expression of contractile proteins in human airway smooth muscle (ASM) cells. ASM cells expressing functional muscarinic M2 and M3 receptors were stimulated with methacholine (MCh), TGF-β1, or their combination for up to 7 days. Western blot analysis revealed a strong induction of sm-α-actin and calponin by TGF-β1, which was increased by MCh in ASM cells. Immunocytochemistry confirmed these results and revealed that the presence of MCh augmented the formation of sm-α-actin stress fibers by TGF-β1. MCh did not augment TGF-β1-induced gene transcription of contractile phenotype markers. Rather, translational processes were involved in the augmentation of TGF-β1-induced contractile protein expression by muscarinic receptor stimulation, including phosphorylation of glycogen synthase kinase-3β and 4E-binding protein 1, which was enhanced by MCh. In conclusion, muscarinic receptor stimulation augments functional effects of TGF-β1 in human ASM cells on cellular processes that underpin ASM remodeling in asthma and COPD.
Candidate Pathways for Promoting Differentiation or Quiescence of Oligodendrocyte Progenitor-like Cells in Glioma
Authors: Dougherty Joseph D. , Fomchenko Elena I. , Akuffo Afua A. , Schmidt Eric , Helmy Karim Y. , Bazzoli Elena , Brennan Cameron W. , Holland Eric C. , Milosevic Ana
Published: August 2012

Platelet-derived growth factor receptor alpha–positive oligodendrocyte progenitor cells (OPC) located within the mature central nervous system may remain quiescent, proliferate, or differentiate into oligodendrocytes. Human glioblastoma multiforme tumors often contain rapidly proliferating oligodendrocyte lineage transcription factor 2 (Olig2)-positive cells that resemble OPCs. In this study, we sought to identify candidate pathways that promote OPC differentiation or quiescence rather than proliferation. Gene expression profiling conducted in both normal murine OPCs and highly proliferative Olig2-positive glioma cells identified all the transcripts associated with the highly proliferative state of these cells and showed that among the various cell types found within the brain, Olig2-positive tumor cells are most similar to OPCs. We then subtracted OPC transcripts found in tumor samples from those found in normal brain samples and identified 28 OPC transcripts as candidates for promoting differentiation or quiescence. Systematic analysis of human glioma data revealed that these genes have similar expression profiles in human tumors and were significantly enriched in genomic deletions, suggesting an antiproliferative role. Treatment of primary murine glioblastoma cells with agonists of one candidate gene, Gpr17, resulted in a decreased number of neurospheres. Together, our findings show that comparison of the molecular phenotype of progenitor cells in tumors to the equivalent cells in the normal brain represents a novel approach for the identification of targeted therapies. Cancer Res; 72(18); 4856–68. ©2012 AACR.
The Microculture-Kinetic (MiCK) Assay: The Role of a Drug-Induced Apoptosis Assay in Drug Development and Clinical Care
Authors: Bosserman Linda , Prendergast Franklyn , Herbst Roy , Fleisher Martin , Salom Emery , Strickland Steven , Raptis Anastasios , Hallquist Allan , Perree Mathieu , Rajurkar Swapnil , Karimi Misagh , Rogers Karl , Davidson Dirk , Willis Carl , Penalver Manuel , Homesley Howard , Burrell Matthew , Garrett Audrey , Rutledge James , Chernick Michael , Presant Cary A.
Published: August 2012

A drug-induced apoptosis assay, termed the microculture-kinetic (MiCK) assay, has been developed. Blinded clinical trials have shown higher response rates and longer survival in groups of patients with acute myelocytic leukemia and epithelial ovarian cancer who have been treated with drugs that show high apoptosis in the MiCK assay. Unblinded clinical trials in multiple tumor types have shown that the assay will be used frequently by clinicians to determine treatment, and when used, results in higher response rates, longer times to relapse, and longer survivals. Model economic analyses suggest possible cost savings in clinical use based on increased generic drug use and single-agent substitution for combination therapies. Two initial studies with drugs in development are promising. The assay may help reduce costs and speed time to drug approval. Correlative studies with molecular biomarkers are planned. This assay may have a role both in personalized clinical therapy and in more efficient drug development. Cancer Res; 72(16); 3901–5. ©2012 AACR.
Rab27a Supports Exosome-Dependent and -Independent Mechanisms That Modify the Tumor Microenvironment and Can Promote Tumor Progression
Authors: Bobrie Angélique , Krumeich Sophie , Reyal Fabien , Recchi Chiara , Moita Luis F. , Seabra Miguel C. , Ostrowski Matias , Théry Clotilde
Published: August 2012

During progression from single cancer cells to a tumor mass and metastases, tumor cells send signals that can subvert their tissue microenvironment. These signals involve soluble molecules and various extracellular vesicles, including a particular type termed exosomes. The specific roles of exosomes secreted in the tumor microenvironment, however, is unclear. The small GTPases RAB27A and RAB27B regulate exocytosis of multivesicular endosomes, which lead to exosome secretion, in human HeLa cells. Here, we used mouse models to show that Rab27a blockade in mammary carcinoma cells decreased secretion of exosomes characterized by endocytic markers, but also of matrix metalloproteinase 9, which is not associated with exosomes. Rab27a blockade resulted in decreased primary tumor growth and lung dissemination of a metastatic carcinoma (4T1), but not of a nonmetastatic carcinoma (TS/A). Local growth of 4T1 tumors required mobilization of a population of neutrophil immune cells induced by Rab27a-dependent secretion of exosomes together with a specific combination of cytokines and/or metalloproteinases. Our findings offer in vivo validation of the concept that exosome secretion can exert key pathophysiologic roles during tumor formation and progression, but they also highlight the idiosyncratic character of the tumor context. Cancer Res; 72(19); 4920–30. ©2012 AACR.
Inactivation of the HIF-1α/PDK3 Signaling Axis Drives Melanoma toward Mitochondrial Oxidative Metabolism and Potentiates the Therapeutic Activity of Pro-Oxidants
Authors: Kluza Jérome , Corazao-Rozas Paola , Touil Yasmine , Jendoubi Manel , Maire Cyril , Guerreschi Pierre , Jonneaux Aurélie , Ballot Caroline , Balayssac Stéphane , Valable Samuel , Corroyer-Dulmont Aurélien , Bernaudin Myriam , Malet-Martino Myriam , de Lassalle Elisabeth Martin , Maboudou Patrice , Formstecher Pierre , Polakowska Renata , Mortier Laurent , Marchetti Philippe
Published: August 2012

Cancer cells can undergo a metabolic reprogramming from oxidative phosphorylation to glycolysis that allows them to adapt to nutrient-poor microenvironments, thereby imposing a selection for aggressive variants. However, the mechanisms underlying this reprogramming are not fully understood. Using complementary approaches in validated cell lines and freshly obtained human specimens, we report here that mitochondrial respiration and oxidative phosphorylation are slowed in metastatic melanomas, even under normoxic conditions due to the persistence of a high nuclear expression of hypoxia-inducible factor-1α (HIF-1α). Pharmacologic or genetic blockades of the HIF-1α pathway decreased glycolysis and promoted mitochondrial respiration via specific reduction in the expression of pyruvate dehydrogenase kinase-3 (PDK3). Inhibiting PDK3 activity by dichloroacetate (DCA) or siRNA-mediated attenuation was sufficient to increase pyruvate dehydrogenase activity, oxidative phosphorylation, and mitochondrial reactive oxygen species generation. Notably, DCA potentiated the antitumor effects of elesclomol, a pro-oxidative drug currently in clinical development, both by limiting cell proliferation and promoting cell death. Interestingly, this combination was also effective against BRAF V600E-mutant melanoma cells that were resistant to the BRAF inhibitor vemurafenib. Cotreatment of melanomas with DCA and elesclomol in vivo achieved a more durable response than single agent alone. Our findings offer a preclinical validation of the HIF-1/PDK3 bioenergetic pathway as a new target for therapeutic intervention in metastatic melanoma, opening the door to innovative combinations that might eradicate this disease. Cancer Res; 72(19); 5035–47. ©2012 AACR.
Effective Photothermal Chemotherapy Using Doxorubicin-Loaded Gold Nanospheres That Target EphB4 Receptors in Tumors
Authors: You Jian , Zhang Rui , Xiong Chiyi , Zhong Meng , Melancon Maritess , Gupta Sanjay , Nick Alpa M. , Sood Anil K. , Li Chun
Published: August 2012

Photothermal ablation (PTA) is an emerging technique that uses near-infrared (NIR) laser light–generated heat to destroy tumor cells. However, complete tumor eradication by PTA therapy alone is difficult because heterogeneous heat distribution can lead to sublethal thermal dose in some areas of the tumor. Successful PTA therapy requires selective delivery of photothermal conducting nanoparticles to mediate effective PTA of tumor cells, and the ability to combine PTA with other therapy modalities. Here, we synthesized multifunctional doxorubicin (DOX)-loaded hollow gold nanospheres (DOX@HAuNS) that target EphB4, a member of the Eph family of receptor tyrosine kinases overexpressed on the cell membrane of multiple tumors and angiogenic blood vessels. Increased uptake of targeted nanoparticles T-DOX@HAuNS was observed in three EphB4-positive tumors both in vitro and in vivo. In vivo release of DOX from DOX@HAuNS, triggered by NIR laser, was confirmed by dual-radiotracer technique. Treatment with T-DOX@HAuNS followed by NIR laser irradiation resulted in significantly decreased tumor growth when compared with treatments with nontargeted DOX@HAuNS plus laser or HAuNS plus laser. The tumors in 6 of the 8 mice treated with T-DOX@HAuNS plus laser regressed completely with only residual scar tissue by 22 days following injection, and none of the treatment groups experienced a loss in body weight. Together, our findings show that concerted chemo-photothermal therapy with a single nanodevice capable of mediating simultaneous PTA and local drug release may have promise as a new anticancer therapy. Cancer Res; 72(18); 4777–86. ©2012 AACR.
RNF8 Regulates Assembly of RAD51 at DNA Double-Strand Breaks in the Absence of BRCA1 and 53BP1
Authors: Nakada Shinichiro , Yonamine Rikako Miyamoto , Matsuo Koichi
Published: August 2012

The tumor suppressor protein BRCA1 localizes to sites of DNA double-strand breaks (DSB), promoting repair by homologous recombination through the recruitment of DNA damage repair proteins. In normal cells, homologous recombination largely depends on BRCA1. However, assembly of the pivotal homologous recombination regulator RAD51 can occur independently of BRCA1 in the absence of 53BP1, another DNA damage response protein. How this assembly process proceeds is unclear, but important to understand in tumor cell settings where BRCA1 is disabled. Here we report that RNF8 regulates BRCA1-independent homologous recombination in 53BP1-depleted cells. RNF8 depletion suppressed the recruitment of RAD51 to DSB sites without affecting assembly or phosphorylation of the replication protein RPA in neocarzinostatin-treated or X-ray-irradiated BRCA1/53BP1-depleted cells. Furthermore, RNF8/BRCA1/53BP1-depleted cells exhibited less efficient homologous recombination than BRCA1/53BP1-depleted cells. Intriguingly, neither RNF8 nor its relative RNF168 were required for RAD51 assembly at DSB sites in 53BP1-expressing cells. Moreover, RNF8-independent RAD51 assembly was found to be regulated by BRCA1. Together, our findings indicate a tripartite regulation of homologous recombination by RNF8, BRCA1, and 53BP1. In addition, our results predict that RNF8 inhibition may be a useful treatment of BRCA1-mutated/53BP1low cancers, which are considered resistant to treatment by PARP1 inhibitors and of marked current clinical interest. Cancer Res; 72(19); 4974–83. ©2012 AACR.
Cardiac Inflammation after Local Irradiation Is Influenced by the Kallikrein-Kinin System
Authors: Sridharan Vijayalakshmi , Tripathi Preeti , Sharma Sunil K. , Moros Eduardo G. , Corry Peter M. , Lieblong Benjamin J. , Kaschina Elena , Unger Thomas , Thöne-Reineke Christa , Hauer-Jensen Martin , Boerma Marjan
Published: August 2012

Radiotherapy of intrathoracic and chest wall tumors may lead to exposure of the heart to ionizing radiation, resulting in radiation-induced heart diseases (RIHD). The main manifestations of RIHD become apparent many years after treatment and include cardiomyopathy and accelerated atherosclerosis. This study examines the role of the kallikrein-kinin system (KKS) in RIHD by investigating the cardiac radiation response in a kininogen-deficient Brown Norway Katholiek (BN/Ka) rat model. BN/Ka rats and wild-type Brown Norway (BN) rats were exposed to local heart irradiation with a single dose of 18 Gy or 24 Gy and were observed for 3 to 6 months. Examinations included in vivo and ex vivo cardiac function, histopathology, gene and protein expression measurements, and mitochondrial swelling assays. Upon local heart irradiation, changes in in vivo cardiac function were significantly less in BN/Ka rats. For instance, a single dose of 24 Gy caused a 35% increase in fractional shortening in BN rats compared with a 16% increase in BN/Ka rats. BN rats, but not BN/Ka rats, showed a 56% reduction in cardiac numbers of CD2-positive cells, and a 57% increase in CD68-positive cells, together with a 52% increase in phosphorylation of extracellular signal–regulated kinase 1/2 (Erk1/2). Local heart irradiation had similar effects on histopathology, mitochondrial changes, and left ventricular mRNA levels of NADPH oxidases in the two genotypes. These results suggest that the KKS plays a role in the effects of radiation on cardiac function and recruitment of inflammatory cells. The KKS may have these effects at least in part by altering Erk1/2 signaling. Cancer Res; 72(19); 4984–92. ©2012 AACR.
Roles for Endothelin Receptor B and BCL2A1 in Spontaneous CNS Metastasis of Melanoma
Authors: Cruz-Muñoz William , Jaramillo Maria L. , Man Shan , Xu Ping , Banville Myriam , Collins Catherine , Nantel Andre , Francia Giulio , Morgan Sherif S. , Cranmer Lee D. , O'Connor-McCourt Maureen D. , Kerbel Robert S.
Published: August 2012

Metastatic spread of melanoma to the central nervous system (CNS) is a common and devastating manifestation of disease progression, which, despite its clinical importance, remains poorly understood with respect to underlying molecular mechanisms. Using a recently developed preclinical model of spontaneous melanoma CNS metastasis, we have identified alterations in expression of endothelin receptor B (EDNRB) as a potential factor that influences brain metastatic potential. Induced overexpression of this gene mediated enhanced overall metastatic disease, and resulted in an increased incidence of spontaneous CNS metastases. In contrast, the overexpression of other highlighted genes, such as BCL2A1, did not affect the incidence of CNS metastases but nevertheless appears to facilitate intracranial tumor growth. The prometastatic effect in the CNS associated with EDNRB appears to be mediated by the interaction with its ligands resulting in enhanced tumor cell proliferation and thus intracranial melanoma growth. That EDNRB contributes to melanoma metastasis is underscored by the fact that its therapeutic inhibition by the EDNRB-specific inhibitor A192621 translated into improved outcomes when treating mice with either visceral metastases or intracranial tumors. The identification of an influential role of EDNRB in CNS melanoma spontaneous metastasis may provide both a target for therapeutic intervention as well as a potential prognostic marker for patients having an increased predisposition for incidence of CNS melanoma metastases. Cancer Res; 72(19); 4909–19. ©2012 AACR.
Mechanism of Drug Efficacy Within the EGF Receptor Revealed by Microsecond Molecular Dynamics Simulation
Authors: Wan Shunzhou , Wright David W. , Coveney Peter V.
Published: August 2012

The EGF receptor (EGFR) regulates important cellular processes including proliferation, differentiation, and apoptosis. EGFR is frequently overexpressed in a range of cancers and is associated with disease progression and treatment. Clinical studies have shown that EGFR mutations confer tumor sensitivity to tyrosine kinase inhibitors in patients with non–small cell lung cancer. In this study, we have conducted molecular dynamics simulations over several microseconds for wild-type and L858R mutant forms of EGFR in the ligand-free state. Close inspection of the conformations and interactions within the binding pocket reveals, converse to the wild type, that the mutant EGFR prefers to bind gefitinib, a targeted anticancer drug, rather than ATP, offering an explanation for why gefitinib is more effective in patients with EGFR mutations than those without. Mol Cancer Ther; 11(11); 2394–400. ©2012 AACR.
Measurement of
S
-Nitrosylation Occupancy in the Myocardium With Cysteine-Reactive Tandem Mass Tags
Authors: Kohr Mark J. , Aponte Angel , Sun Junhui , Gucek Marjan , Steenbergen Charles , Murphy Elizabeth
Published: August 2012

Rationale:

S-nitrosylation (SNO) is a reversible, thiol-based protein modification that plays an important role in the myocardium by protecting critical cysteine residues from oxidation. However, little is known with regard to the percentage of a given protein that is modified by SNO (ie, SNO occupancy). Current methods allow for the relative quantification of SNO levels, but not for the determination of SNO occupancy.

Objective:

To develop a method for the measurement of SNO occupancy, and apply this methodology to determine SNO occupancy in the myocardium.

Methods and Results:

We developed a differential cysteinereactive tandem mass tag (cysTMT) labeling procedure for the measurement of SNO occupancy. To validate this cysTMT labeling method, we treated whole-heart homogenates with the S-nitrosylating agent S-nitrosoglutathione and determined maximal SNO occupancy. We also examined SNO occupancy under more physiological conditions and observed that SNO occupancy is low for most protein targets at baseline. Following ischemic preconditioning, SNO occupancy increased to an intermediate level compared to baseline and Snitrosoglutathione treatment, and this is consistent with the ability of SNO to protect against cysteine oxidation.

Conclusions:

This novel cysTMT labeling approach provides a method for examining SNO occupancy in the myocardium. Using this approach, we demonstrated that IPC-induced SNO occupancy levels are sufficient to protect against oxidation.
Myocardial Relaxation, Restoring Forces, and Early-Diastolic Load Are Independent Determinants of Left Ventricular Untwisting Rate
Authors: Opdahl Anders , Remme Espen W. , Helle-Valle Thomas , Edvardsen Thor , Smiseth Otto A.
Published: August 2012

Background—

Peak left ventricular (LV) untwisting rate (UTR) has been introduced as a clinical marker of diastolic function. This study investigates if early-diastolic load and restoring forces are determinants of UTR in addition to the rate of LV relaxation.

Methods and Results—

In 10 anesthetized dogs we measured UTR by sonomicrometry and speckle tracking echocardiography at varying LV preloads, increased contractility, and myocardial ischemia. UTR was calculated as the time derivative of LV twist. Because preload modified end-diastolic twist, LV systolic twist was calculated in absolute terms with reference to the end-diastolic twist configuration at baseline. Relaxation rate was measured as the time constant (τ) of LV isovolumic pressure decay. Early-diastolic load was measured as LV pressure at the time of mitral valve opening. Circumferential-longitudinal shear strain was used as an index of restoring forces. In a multivariable mixed model analysis a strong association was observed between UTR and LV pressure at the time of mitral valve opening (parameter estimate [β]=6.9;
P
<0.0001), indicating an independent effect of early-diastolic load. Furthermore, the associations between UTR and circumferential-longitudinal shear strain (β=−11.3;
P
<0.0001) and τ (β=−1.6,
P
<0.003) were consistent with independent contributions from restoring forces and rate of relaxation. Maximal UTR before mitral valve opening, however, was determined only by relaxation rate and restoring forces.

Conclusions—

The present study indicates that early-diastolic load, restoring forces, and relaxation rate are independent determinants of peak UTR. However, only relaxation rate and restoring forces contributed to UTR during isovolumic relaxation.
Cyclooxygenase-2–Derived Prostacyclin Regulates Arterial Thrombus Formation by Suppressing Tissue Factor in a Sirtuin-1–Dependent-Manner
Authors: Barbieri Silvia S. , Amadio Patrizia , Gianellini Sara , Tarantino Eva , Zacchi Elena , Veglia Fabrizio , Howe Louise R. , Weksler Babette B. , Mussoni Luciana , Tremoli Elena
Published: August 2012

Background—

Selective inhibitors of cyclooxygenase (COX)-2 increase the risk of myocardial infarction and thrombotic events, but the responsible mechanisms are not fully understood.

Methods and Results—

We found that ferric chloride–induced arterial thrombus formation was significantly greater in COX-2 knockout compared with wild-type mice. Cross-transfusion experiments excluded the likelihood that COX-2 knockout platelets, despite enhanced aggregation responses to collagen and thrombin, are responsible for increased arterial thrombus formation in COX-2 knockout mice. Importantly, we observed that COX-2 deletion decreased prostacyclin synthase and production and peroxisome proliferator-activated receptor- and sirtuin-1 (SIRT1) expression, with consequent increased upregulation of tissue factor (TF), the primary initiator of blood coagulation. Treatment of wild-type mice with a prostacyclin receptor antagonist or a peroxisome proliferator-activated receptor-δ antagonist, which predisposes to arterial thrombosis, decreased SIRT1 expression and increased TF activity. Conversely, exogenous prostacyclin or peroxisome proliferator-activated receptor-δ agonist completely reversed the thrombotic phenotype in COX-2 knockout mice, restoring normal SIRT1 levels and reducing TF activity. Furthermore, inhibition of SIRT1 increased TF expression and activity and promoted generation of occlusive thrombi in wild-type mice, whereas SIRT1 activation was sufficient to decrease abnormal TF activity and prothrombotic status in COX-2 knockout mice.

Conclusions—

Modulation of SIRT1 and hence TF by prostacyclin/peroxisome proliferator-activated receptor-δ pathways not only represents a new mechanism in controlling arterial thrombus formation but also might be a useful target for therapeutic intervention in the atherothrombotic complications associated with COX-2 inhibitors.
The Cell Motility Modulator Slit2 Is a Potent Inhibitor of Platelet Function
Authors: Patel Sajedabanu , Huang Yi-Wei , Reheman Adili , Pluthero Fred G. , Chaturvedi Swasti , Mukovozov Ilya M. , Tole Soumitra , Liu Guang-Ying , Li Ling , Durocher Yves , Ni Heyu , Kahr Walter H.A. , Robinson Lisa A.
Published: August 2012

Background—

Vascular injury and atherothrombosis involve vessel infiltration by inflammatory leukocytes, migration of medial vascular smooth muscle cells to the intimal layer, and ultimately acute thrombosis. A strategy to simultaneously target these pathological processes has yet to be identified. The secreted protein, Slit2, and its transmembrane receptor, Robo-1, repel neuronal migration in the developing central nervous system. More recently, it has been appreciated that Slit2 impairs chemotaxis of leukocytes and vascular smooth muscle cells toward diverse inflammatory attractants. The effects of Slit2 on platelet function and thrombus formation have never been explored.

Methods and Results—

We detected Robo-1 expression in human and murine platelets and megakaryocytes and confirmed its presence via immunofluorescence microscopy and flow cytometry. In both static and shear microfluidic assays, Slit2 impaired platelet adhesion and spreading on diverse extracellular matrix substrates by suppressing activation of Akt. Slit2 also prevented platelet activation on exposure to ADP. In in vivo studies, Slit2 prolonged bleeding times in murine tail bleeding assays. Using intravital microscopy, we found that after mesenteric arteriolar and carotid artery injury, Slit2 delayed vessel occlusion time and prevented the stable formation of occlusive arteriolar thrombi.

Conclusions—

These data demonstrate that Slit2 is a powerful negative regulator of platelet function and thrombus formation. The ability to simultaneously block multiple events in vascular injury may allow Slit2 to effectively prevent and treat thrombotic disorders such as myocardial infarction and stroke.
Rwanda
Authors: Stanfield John H.
Published: August 2012

Historical oriented macro-sociology of knowledge analyses of the origins and development of nations and other societies and global formations are usually confined to the examination of the United States and European countries and Europe as a continental global space. In this essay the author plays with ideas and tries on sociology of knowledge concepts for size in exploring the pre-colonial, colonial, and genocide apartheid societal roots of post-genocide Rwanda as an East-Central African society emerging symbolically as an extraordinary 21st century Post-Cold War African State.
Knowledge Practices, Institutional Strategies, and External Influences in the Making of an Interdisciplinary Field
Authors: Wood Christine V.
Published: August 2012

This article analyzes the formation of women’s and gender studies as an interdisciplinary academic field. The author draws on comparative case studies of three early-adopter women’s studies departments from historical records and interviews with faculty members. Existing research on disciplinary formation focuses on the way practitioners forge institutional niches for new academic programs but not on sustained analysis of knowledge-making processes. Research on processes of knowledge construction focuses on established research situations, such as physics labs or literary seminars, as opposed to newly emerging fields and fields with politicized origins. The author combines institutional and practice-oriented approaches to explain the formation of knowledge-making agendas in new interdisciplinary research fields. In the case of women’s and gender studies, practitioners’ strategies for promoting the growth of their programs corresponded with the kinds of knowledge that they produced. In the period of adoption in the 1970s, scholars across the three units defined the intellectual goals of women’s studies similarly in working to redress the lack of research on women in existing disciplines and to analyze social problems affecting contemporary women’s lives. Each program acquired institutional stability, which involved the negotiation of budgeted faculty hires in specific research areas and the development of degree programs. Over time, practitioners at each program justified the continued existence of women’s studies programs by claiming expertise in a diverse range of topics relating to human gender and sexual experience and by constituting their academic programs in relation to local intellectual agendas.
The Supervision Competency
Authors: Grus Catherine L.
Published: August 2012

The competency of supervision is one that is receiving increased attention in the professional psychology literature. References to supervision in historical and current competency models including the benchmarks are described to illustrate this. Ways in which our understanding of the supervision competency and competency-based education and training broadly is advanced through this major contribution are noted, including focus on empirical support for the essential components of the competency, considerations of how competency models work and do not in other countries, and attention to the interrelationships between competencies. While this major contribution helps expand the scholarly literature on the competency of supervision, challenges remain in the broader adoption of competency-based education and training, including program and systems-level support and the need to identify effective education and training practices to promote competency development.
Correlation of the bridging model predictions for triaxial failure strengths of composites with experiments
Authors: Huang Z-M , Zhou Y-X
Published: August 2012

The bridging model was incorporated with a pseudo three-dimensional laminate theory to predict the strengths and deformation curves of a set of typical fiber‐reinforced composites under triaxial loads. The prediction was achieved using the constituent properties and geometric parameters of the composites based on the information provided by the WWFE-II’s organizers. In the present paper, the ‘blind’ predictions shown in Part A of this work are compared with the experimental results. The overall correlations between the predictions and the experiments are reasonable but somewhat conservative, especially when shear failures or large hydrostatic pressures are involved. Satisfactory improvement has been achieved when the modified maximum compressive stress failure criterion proposed previously is applied to detect fiber failure as well. Even better predictions for a number of the problems have been obtained if the constituent material properties directly taken from the organizers, rather than retrieved from the laminae data, are employed.
The influence of montmorillonite on mechanical, thermal and fire retardation properties of vinylester/glass composites
Authors: Mahesh KR Vishnu , Murthy HN Narasimha , Kumaraswamy BE , Sridhar R , Krishna M , Sherigara BS
Published: August 2012

This paper presents the influence of dispersing montmorillonite in 2 to 8 wt% in vinylester on the mechanical, thermal and fire retardation behaviour of vinylester/glass composites. X-ray diffraction and transmission electron microscopy results of montmorillonite/vinylester showed exfoliation of montmorillonite up to 4 wt% loading. Glass transition temperature ( Tg) and microhardness of montmorillonite/vinylester increased with increase in montmorillonite loading. Tensile strength, interlaminar shear strength, flexural strength, impact strength and fatigue life of vinylester/glass increased by the addition of 4 wt% montmorillonite. Thermogravimetric analysis showed decrease in thermal degradation in 4 wt%/montmorillonite/vinylester compared to 2 wt%/montmorillonite/vinylester. Horizontal and vertical burning rates of vinylester/glass decreased with the addition of montmorillonite. Limiting oxygen index increased by 18% and 25% with the addition of 8 wt% montmorillonite to vinylester and vinylester/glass respectively. Scanning electron microscopy was used to study montmorillonite, vinylester and glass fibre interfacial strengths and the fatigue damage mechanism.
Drop-weight impact damage of three-dimensional angle-interlock woven composites
Authors: Sun B , Zhang R , Zhang Q , Gideon R , Gu B
Published: August 2012

The drop-weight impact behavior of three-dimensional angle-interlock woven glass fiber/unsaturated polyester resin composites was investigated with a drop-weight impact tester (Instron Dynatup 9250 impact tester). A unit cell model based on the maximum stress failure criterion and critical damage area failure theory was established to define the material properties and stiffness degradation of the three-dimensional angle-interlock woven composites. A user-defined subroutine vectorized user-material was developed to connect with the commercial finite element analysis package ABAQUS/Explicit. The drop-weight impact damage and impact load-displacement curves were calculated and compared with those in the experimental. Good agreements between the experimental and finite element analysis results proved the validity of the unit cell model and the subroutine vectorized user-material. The unit cell model is expected to be extended for the study of the impact damage of three-dimensional angle-interlock woven composites structures.
Microbiological Characterization in Children with Aggressive Periodontitis
Authors: Shaddox L.M. , Huang H. , Lin T. , Hou W. , Harrison P.L. , Aukhil I. , Walker C.B. , Klepac-Ceraj V. , Paster B.J.
Published: August 2012

The objective of this study was to characterize the subgingival microbiota of African-American children with Localized Aggressive Periodontitis (LAP). Fifty-one children were included. Subgingival plaque samples were taken from diseased (DD) and healthy sites (DH) in LAP and from healthy sites in HS and HC and analyzed by 16S rRNA-based microarrays. Aggregatibacter actinomycetemcomitans (Aa) was the only species found to be both more prevalent (OR = 8.3, p = 0.0025) and abundant (p < 0.01) in DD. Filifactor alocis (Fa) was also found to be more prevalent in DD (OR 2.31, CI 1.06-5.01, p = 0.03). Most prevalent species in healthy sites were Selenomonas spp, Veillonella spp, Streptococcus spp, Bergeyella sp, and Kingella oralis. Overall, Streptococcus spp, Campylobacter gracilis, Capnocytophaga granulosa, Haemophilus parainfluenzae, and Lautropia mirabilis were most abundant in healthy children, while Aa, Fa, Tannerella sp, Solobacterium moorei, Parvimonas micra, and Capnocytophaga sp were most abundant in LAP. Based on a comprehensive analysis with 16S rRNA-based microarrays, Aa was strongly associated and site-specific in LAP. In contrast, other species were found to be associated with healthy sites and individuals (ClinicalTrials.gov number CT01330719).

Abbreviations: healthy site in healthy sibling (HS); healthy site in healthy control child (HC).
Training for Efficiency
Authors: Szymczak Julia E. , Bosk Charles L.
Published: August 2012

Medical residency is a period of intense socialization with a heavy workload. Previous sociological studies have identified efficiency as a practical skill necessary for success. However, many contextual features of the training environment have undergone dramatic change since these studies were conducted. What are the consequences of these changes for the socialization of residents to time management and the development of a professional identity? Based on observations of and interviews with internal medicine residents at three training programs, we find that efficiency is both a social norm and strategy that residents employ to manage a workload for which the demand for work exceeds the supply of time available to accomplish it. We found that residents struggle to be efficient in the face of seemingly intractable “systems” problems. Residents work around these problems, and in doing so develop a tolerance for organizational vulnerabilities.
An evaluation of the ramp metering effectiveness in reducing carbon dioxide emissions
Authors: Bae Sang-Hoon , Heo Tae-Young , Ryu Byoung-Yong
Published: August 2012

In this study, we develop a methodology to estimate the effectiveness of ramp metering in reducing CO2 emissions. Ramp metering is one of several Intelligent Transportation Systems (ITS) applications to control traffic flow. In this paper in order to estimate the reduced emissions, we followed the procedure supported by the United Nations Framework Convention on Climate Change (UN-FCCC). And ramp metering causes some drivers to change their routes and affects CO2 emissions on the ramp and on the main lane. With these issues in mind, we performed Stated Preference analysis to determine the degree of driver preference for individual traffic situations.The Traffic Software Integrated System (TSIS) simulation program was used to verify the CO2 measurement model. The TSIS simulation showed that the reduction in CO2 emissions was 818.4 kg/h and that the decrease in the effectiveness was 7.3%. It also revealed that ramp metering reduced the CO2. emissions to 3,273.6kg emissions per day and 1,194.9 ton per year. In conclusion we found that ramp metering is effective in reducing CO2 emissions.