bluuebunny/crossref_metadata_2025 huggingface dataset:
The national head and neck histopathology external quality assurance scheme: evolution, design, and analysis of 11 circulations from 1999 to 2005
Authors: Woolgar J A
Published: February 2006

The background and design of a specialised head and neck histopathology external quality assurance (assessment) scheme with optional oral and ENT arms is described. Participation (submission of response forms) exceeded 85% in eight of 11 slide circulations. In 60% of the 168 circulated cases, up to 33% (and in occasional cases, up to 56%) of respondents gave incomplete or wrong responses owing to a lack of awareness of specific diagnostic entities or to the misinterpretation of specific histological features. In all, there were 118 wrong responses, of which 58% could be considered “potentially serious”. The scheme incorporates several design features which optimise the educational value. The stringent marking of cases, and the flagging of performances showing “a meaningful deviation in standard” based on the decision of peer members rather than a rigid numerical formula, encourages high standards.
Retinoic acid can induce markers of endocrine transdifferentiation in pancreatic ductal adenocarcinoma: preliminary observations from an in vitro cell line model
Authors: El-Metwally T H , Hussein M R , Abd-El-Ghaffar S Kh , Abo-El-Naga M M , Ulrich A B , Pour P M
Published: February 2006

Background and hypothesis:The pancreatic ductal adenocarcinoma (HPAF) cells have a multipotent stem cell potential. It was hypothesised that all-trans-retinoic acid (atRA) can induce transdifferentiation of these cells into cells with an endocrine phenotype.

Material and methods:To explore this hypothesis, an in vitro system of cells was established. Some cells were treated with atRA at concentrations of 100 nmol/l (non-apoptosis-inducing) and 5 μmol/l (apoptosis-inducing) and harvested. Cells were examined for cell cycle kinetics, apoptosis (terminal deoxynucleotidyl transferase assay and p53 protein expression) and immunomorphological features of redifferentiation (MUC1 and DUPAN-2) and endocrine transdifferentiation (insulin, somatostatin, glucagon, neurone-specific enolase) by using immunoperoxidase staining methods. Levels of insulin, transforming growth factor (TGF) β2, TGFα and epidermal growth factor receptor (EGFR) were measured by enzyme-linked immunosorbent assay (ELISA). The vehicle-treated cells served as a control group.

Results:When compared with untreated cells, cells treated with 100 nmol/l and 5 μmol/l atRA were observed to show (1) decreased proliferative activity (cpm) as indicated by decreased incorporation of thymidine labelled with hydrogen-3; (2) cell cycle arrest; (3) increased apoptotic activity associated with p53 protein overexpression; (4) upregulated expression of the transdifferentiation and redifferentiation markers; (5) morphological changes indicative of transdifferentiation (increased cell size and appearance of dendrites); (6) decreased production of EGFR; (7) upregulation of TGFα and TGFβ2; and (8) increase in basal and glucose-induced insulin secretion.

Conclusions:Functional endocrine transdifferentiation can be induced in HPAF lines by atRA. Further investigations are mandated to explore the underlying mechanisms of this transdifferentiation and to explore its in vivo extrapolation.
RECENT ADVANCES AND DESIGN TRENDS IN CMOS RADIO FREQUENCY INTEGRATED CIRCUITS
Authors: ALLSTOT DAVID J. , ANIRUDDHAN SANKARAN , CHU MIN , PARAMESH JEYANANDH , SHEKHAR SUDIP
Published: February 2006

Several state-of-the-art wireless receiver architectures are presented including the traditional super-heterodyne, the image-reject heterodyne, the direct-conversion, and the very-low intermediate frequency (VLIF). The case studies are followed by a detailed view of receiver building blocks: low-noise amplifiers (LNA), mixers, and voltage-controlled oscillators (VCO). Two popular topologies currently exist for LNAs: the common-gate configuration, which offers low power consumption with superior stability, robustness and linearity performance, and its common-source counterpart, which provides comparatively higher gain and lower noise figure. Aside from the traditional passive and active Gilbert mixers, the even-harmonic and masking-quadrature mixers are developed to combat second-order non-linearity and improve image-rejection, respectively. For quadrature carrier generation, the degeneration-injected QVCO is superior to the cascode-injected QVCO both in terms of phase noise and tuning range. The Colpitts QVCO is attractive as a low-noise alternative as it does not disturb the output voltage as much as its traditional LC counterpart and thus offers lower phase noise.
EQUALIZERS FOR HIGH-SPEED SERIAL LINKS
Authors: HANUMOLU PAVAN KUMAR , WEI GU-YEON , MOON UN-KU
Published: February 2006

In this tutorial paper we present equalization techniques to mitigate inter-symbol interference (ISI) in high-speed communication links. Both transmit and receive equalizers are analyzed and high-speed circuits implementing them are presented. It is shown that a digital transmit equalizer is the simplest to design, while a continuous-time receive equalizer generally provides better performance. Decision feedback equalizer (DFE) is described and the loop latency problem is addressed. Finally, techniques to set the equalizer parameters adaptively are presented.
AN APPLICATION OF NEUTRIX CALCULUS TO QUANTUM FIELD THEORY
Authors: NG Y. JACK , VAN DAM H.
Published: February 2006

Neutrices are additive groups of negligible functions that do not contain any constants except 0. Their calculus was developed by van der Corput and Hadamard in connection with asymptotic series and divergent integrals. We apply neutrix calculus to quantum field theory, obtaining finite renormalizations in the loop calculations. For renormalizable quantum field theories, we recover all the usual physically observable results. One possible advantage of the neutrix framework is that effective field theories can be accommodated. Quantum gravity theories will then appear to be more manageable.
PAIR PRODUCTION IN A STRONG ROTATING MAGNETIC FIELD: THE EFFECT OF A WEAK BACKGROUND GRAVITATIONAL FIELD
Authors: DI PIAZZA ANTONINO
Published: February 2006

In this paper we present the calculation of the production probability of an e-–e+ pair in the presence of a strong, uniform and slowly rotating magnetic field by taking into account the presence of a weak background gravitational field. The gravitational field is treated perturbatively and it is shown how the curvature of the space–time metric induced by the gravitational field itself enhances the production probability with respect to the analogous one obtained in Minkowski space–time.
AN ALTERNATIVE METHOD TO OBTAIN THE MUON CHARGE RATIO AT SEA LEVEL
Authors: PORTELLA H. M. , SHIGUEOKA H. , DE OLIVEIRA L. C. S. , LIMA C. E. C.
Published: February 2006

The vertical muon charge ratio generated from hadron showers in the earth's atmosphere is obtained accurately in the energy range from a few GeV to several TeV. To solve the hadron diffusion equations we apply the analytical method based on depth-like ordered exponential operator. A comparison among our calculations (with and without scaling violation) with the measured ratio and Lipari's analytical calculation is made. Our differential muon fluxes are also compared with data at sea level.
DOUBLE STRUCTURES AND DOUBLE SYMMETRIES FOR THE EINSTEIN–KALB–RAMOND THEORY
Authors: GAO YA-JUN
Published: February 2006

We further study the two-dimensional reduced Einstein–Kalb–Ramond (EKR) theory in the axisymmetric case by using the so-called double-complex function method. We find a doubleness symmetry of this theory and exploit it so that some double-complex d×d matrix Ernst-like potential can be constructed, and the associated equations of motion can be extended into a double-complex matrix Ernst-like form. Then we give a double symmetry group [Formula: see text] for the EKR theory and verify that its action can be realized concisely by a double-complex matrix, form generalization of the fractional linear transformation on the Ernst potential. These results demonstrate that the theory under consideration possesses more and richer symmetry structures. Moreover, as an application, we obtain an infinite chain of double-solutions of the EKR theory showing that the double-complex method is more effective. Some of the results in this paper cannot be obtained by the usual (nondouble) scheme.
Measurement of Ca2+signaling dynamics in exocrine cells with total internal reflection microscopy
Authors: Won Jong Hak , Yule David I.
Published: February 2006

In nonexcitable cells, such as exocrine cells from the pancreas and salivary glands, agonist-stimulated Ca2+signals consist of both Ca2+release and Ca2+influx. We have investigated the contribution of these processes to membrane-localized Ca2+signals in pancreatic and parotid acinar cells using total internal reflection fluorescence (TIRF) microscopy (TIRFM). This technique allows imaging with unsurpassed resolution in a limited zone at the interface of the plasma membrane and the coverslip. In TIRFM mode, physiological agonist stimulation resulted in Ca2+oscillations in both pancreas and parotid with qualitatively similar characteristics to those reported using conventional wide-field microscopy (WFM). Because local Ca2+release in the TIRF zone would be expected to saturate the Ca2+indicator (Fluo-4), these data suggest that Ca2+release is occurring some distance from the area subjected to the measurement. When acini were stimulated with supermaximal concentrations of agonists, an initial peak, largely due to Ca2+release, followed by a substantial, maintained plateau phase indicative of Ca2+entry, was observed. The contribution of Ca2+influx and Ca2+release in isolation to these near-plasma membrane Ca2+signals was investigated by using a Ca2+readmission protocol. In the absence of extracellular Ca2+, the profile and magnitude of the initial Ca2+release following stimulation with maximal concentrations of agonist or after SERCA pump inhibition were similar to those obtained with WFM in both pancreas and parotid acini. In contrast, when Ca2+influx was isolated by subsequent Ca2+readmission, the Ca2+signals evoked were more robust than those measured with WFM. Furthermore, in parotid acinar cells, Ca2+readdition often resulted in the apparent saturation of Fluo-4 but not of the low-affinity dye Fluo-4-FF. Interestingly, Ca2+influx as measured by this protocol in parotid acinar cells was substantially greater than that initiated in pancreatic acinar cells. Indeed, robust Ca2+influx was observed in parotid acinar cells even at low physiological concentrations of agonist. These data indicate that TIRFM is a useful tool to monitor agonist-stimulated near-membrane Ca2+signals mediated by Ca2+influx in exocrine acinar cells. In addition, TIRFM reveals that the extent of Ca2+influx in parotid acinar cells is greater than pancreatic acinar cells when compared using identical methodologies.
Left ventricular hypertrophy in mice with a cardiac-specific overexpression of interleukin-1
Authors: Nishikawa Kenichiro , Yoshida Mikoto , Kusuhara Masatoshi , Ishigami Norio , Isoda Kikuo , Miyazaki Kohji , Ohsuzu Fumitaka
Published: February 2006

Recent studies have identified the importance of proinflammatory cytokines in the development of left ventricular (LV) hypertrophy. However, the precise role of interleukin-1 (IL-1), one of the major proinflammatory cytokines, in the myocardium is not fully understood. In this study, we investigated the pathophysiological consequences of cardiac expression of IL-1 in vivo. We generated mice with a cardiac-specific overexpression of human IL-1α. We then analyzed their heart morphology and functions. Histological and echocardiographic analyses revealed concentric LV hypertrophy with preserved LV systolic function in the mice. Our results suggest that myocardial expression of IL-1 is sufficient to cause LV hypertrophy.
Docosahexaenoic acid induces ciap1 mRNA and protects human endothelial cells from stress-induced apoptosis
Authors: Pfrommer Claudia A. , Erl Wolfgang , Weber Peter C.
Published: February 2006

Induction of apoptosis represents a potential reaction of endothelial cells (ECs) after injury of the vascular endothelium. Beneficial effects of n–3 polyunsaturated fatty acids (PUFAs) in vascular diseases are widely recognized although the responsible mechanisms are not fully understood. Because it is not known whether PUFAs modulate EC apoptosis, we investigated the effects of n–3 and n–6 PUFAs on 4-hydroxynonenal (HNE)-induced EC apoptosis by annexin V staining and caspase-3 activation assays. Pretreatment with the n–3 fatty acid docosahexaenoic acid (DHA) reduced HNE-induced EC apoptosis. DHA-treated cells did not show the pronounced drop in intracellular GSH after HNE exposure seen in vehicle- or n–6 arachidonic acid-treated cells. This is most likely due to increased GSH levels in DHA-treated cells. Furthermore, DHA pretreatment increased ciap1 mRNA levels and transfection of cIAP1 small interfering RNA abolished the protective effect of DHA in HNE-induced apoptosis in HUVECs. Thus pretreatment of HUVECs with DHA reduces HNE-induced oxidative stress and apoptosis, and the protective effects of DHA seem to be dependent on cIAP1. The results provide a possible new mechanism for the atheroprotective effects of n–3 fatty acids in vascular disease.
Mesenchymal stem cell injection after myocardial infarction improves myocardial compliance
Authors: Berry Mark F. , Engler Adam J. , Woo Y. Joseph , Pirolli Timothy J. , Bish Lawrence T. , Jayasankar Vasant , Morine Kevin J. , Gardner Timothy J. , Discher Dennis E. , Sweeney H. Lee
Published: February 2006

Cellular therapy for myocardial injury has improved ventricular function in both animal and clinical studies, though the mechanism of benefit is unclear. This study was undertaken to examine the effects of cellular injection after infarction on myocardial elasticity. Coronary artery ligation of Lewis rats was followed by direct injection of human mesenchymal stem cells (MSCs) into the acutely ischemic myocardium. Two weeks postinfarct, myocardial elasticity was mapped by atomic force microscopy. MSC-injected hearts near the infarct region were twofold stiffer than myocardium from noninfarcted animals but softer than myocardium from vehicle-treated infarcted animals. After 8 wk, the following variables were evaluated: MSC engraftment and left ventricular geometry by histological methods, cardiac function with a pressure-volume conductance catheter, myocardial fibrosis by Masson Trichrome staining, vascularity by immunohistochemistry, and apoptosis by TdT-mediated dUTP nick-end labeling assay. The human cells engrafted and expressed a cardiomyocyte protein but stopped short of full differentiation and did not stimulate significant angiogenesis. MSC-injected hearts showed significantly less fibrosis than controls, as well as less left ventricular dilation, reduced apoptosis, increased myocardial thickness, and preservation of systolic and diastolic cardiac function. In summary, MSC injection after myocardial infarction did not regenerate contracting cardiomyocytes but reduced the stiffness of the subsequent scar and attenuated postinfarction remodeling, preserving some cardiac function. Improving scarred heart muscle compliance could be a functional benefit of cellular cardiomyoplasty.
Production of NAADP and its role in Ca2+mobilization associated with lysosomes in coronary arterial myocytes
Authors: Zhang Fan , Zhang Guo , Zhang Andrew Y. , Koeberl Matthew J. , Wallander Eryn , Li Pin-Lan
Published: February 2006

The present study was designed to determine the production of nicotinic acid adenine dinucleotide phosphate (NAADP) and its role associated with lysosomes in mediating endothelin-1 (ET-1)-induced vasoconstriction in coronary arteries. HPLC assay showed that NAADP was produced in coronary arterial smooth muscle cells (CASMCs) via endogenous ADP-ribosyl cyclase. Fluorescence microscopic analysis of intracellular Ca2+concentration ([Ca2+]i) in CASMCs revealed that exogenous 100 nM NAADP increased [Ca2+]iby 711 ± 47 nM. Lipid bilayer experiments, however, demonstrated that NAADP did not directly activate ryanodine (Rya) receptor Ca2+release channels on the sarcoplasmic reticulum. In CASMCs pretreated with 100 nM bafilomycin A1 (Baf), an inhibitor of lysosomal Ca2+release and vacuolar proton pump function, NAADP-induced [Ca2+]iincrease was significantly abolished. Moreover, ET-1 significantly increased NAADP formation in CASMCs and resulted in the rise of [Ca2+]iin these cells with a large increase in global Ca2+level of 1,815 ± 84 nM. Interestingly, before this large Ca2+increase, a small Ca2+spike with an increase in [Ca2+]iof 529 ± 32 nM was observed. In the presence of Baf (100 nM), this ET-1-induced two-phase [Ca2+]iresponse was completely abolished, whereas Rya (50 μM) only markedly blocked the ET-1-induced large global Ca2+increase. Functional studies showed that 100 nM Baf significantly attenuated ET-1-induced maximal constriction from 82.26 ± 4.42% to 51.80 ± 4.36%. Our results suggest that a lysosome-mediated Ca2+regulatory mechanism via NAADP contributes to ET-1-induced Ca2+mobilization in CASMCs and consequent vasoconstriction of coronary arteries.
Cardiac fibrogenesis in magnesium deficiency: a role for circulating angiotensin II and aldosterone
Authors: Sapna S. , Ranjith S. K. , Shivakumar K.
Published: February 2006

Mechanisms underlying cardiac fibrogenesis in magnesium deficiency are unclear. It was reported earlier from this laboratory that serum from magnesium-deficient rats has a more pronounced stimulatory effect on cell proliferation, net collagen production, and superoxide generation in adult rat cardiac fibroblasts than serum from rats on the control diet. The profibrotic serum factors were, however, not identified. This study tested the hypothesis that circulating angiotensin II may modulate cardiac fibroblast activity in hypomagnesemic rats. Male Sprague-Dawley rats were pair-fed a magnesium-deficient (0.0008% Mg) or -sufficient (0.05%) diet for 6 days, and the effects of serum from these rats on [3H]thymidine and [3H]proline incorporation into cardiac fibroblasts from young adult rats were evaluated in the presence of losartan, an angiotensin II type 1 (AT1) receptor antagonist, and spironolactone, an aldosterone antagonist. Losartan and spironolactone markedly attenuated the stimulatory effects in vitro of serum from the magnesium-deficient and control groups, but the inhibitory effects were considerably higher in cells exposed to serum from magnesium-deficient animals. Circulating and cardiac tissue levels of angiotensin II were significantly elevated in magnesium-deficient animals (67.6% and 93.1%, respectively, vs. control). Plasma renin activity was 61.9% higher in magnesium-deficient rats, but serum angiotensin-converting enzyme activity was comparable in the two groups. Furthermore, preliminary experiments in vivo using enalapril supported a role for angiotensin II in magnesium deficiency. There was no significant difference between the groups in serum aldosterone levels. The findings suggest that circulating angiotensin II and aldosterone may stimulate fibroblast activity and contribute to a fibrogenic response in the heart in magnesium deficiency.
Inhibition of cardiac contractility by 5-hydroxydecanoate and tetraphenylphosphonium ion: a possible role of mitoKATP in response to inotropic stress
Authors: Garlid Keith D. , Puddu Paolo E. , Pasdois Philippe , Costa Alexandre D. T. , Beauvoit Bertrand , Criniti Anna , Tariosse Liliane , Diolez Philippe , Santos Pierre Dos
Published: February 2006

This study investigates the role of the mitochondrial ATP-sensitive K+ channel (mitoKATP) in response to positive inotropic stress. In Langendorff-perfused rat hearts, inotropy was induced by increasing perfusate calcium to 4 mM, by adding 80 μM ouabain or 0.25 μM dobutamine. Each of these treatments resulted in a sustained increase in rate-pressure product (RPP) of ∼60%. Inhibition of mitoKATP by perfusion of 5-hydroxydecanoate (5-HD) or tetraphenylphosphonium before induction of inotropic stress resulted in a marked attenuation of RPP. Inhibition of mitoKATP after induction of stress caused the inability of the heart to maintain a high-work state. In human atrial fibers, the increase in contractility induced by dobutamine was inhibited 60% by 5-HD. In permeabilized fibers from the Langendorff-perfused rat hearts, inhibition of mitoKATP resulted, in all cases, in an alteration of adenine nucleotide compartmentation, as reflected by a 60% decrease in the half-saturation constant for ADP [ K1/2 (ADP)]. We conclude that opening of cardiac mitoKATP is essential for an appropriate response to positive inotropic stress and propose that its involvement proceeds through the prevention of stress-induced decrease in mitochondrial matrix volume. These results indicate a physiological role for mitoKATP in inotropy and, by extension, in heart failure.
Sex differences in myocardial infarct size are abolished by sarcolemmal KATPchannel blockade in rat
Authors: Johnson Micah S. , Moore Russell L. , Brown David A.
Published: February 2006

This study was conducted to examine the relationship between myocardial ATP-sensitive potassium (KATP) channels and sex differences in myocardial infarct size after in vitro ischemia-reperfusion (I/R). Hearts from adult male and female Sprague-Dawley rats were excised and exposed to an I/R protocol (1 h of ischemia, followed by 2 h of reperfusion) on a modified Langendorff apparatus. Hearts from female rats showed significantly smaller infarct sizes than hearts from males (23 ± 4 vs. 40 ± 5% of the zone at risk, respectively; P < 0.05). Administration of HMR-1098, a sarcolemmal KATPchannel blocker, abolished the sex difference in infarct size (42 ± 4 vs. 45 ± 5% of the zone at risk in hearts from female and male rats, respectively; P = not significant). Further experiments showed that blocking the KATPchannels in ischemia, and not reperfusion, was sufficient to increase infarct size in female rats. These data demonstrate that sarcolemmal KATPchannels are centrally involved in mechanisms that underlie sex differences in the susceptibility of the intact heart to I/R injury.
Regional heterogeneity in acetylcholine-induced relaxation in rat vascular bed: role of calcium-activated K+channels
Authors: Hilgers Rob H. P. , Todd Joseph , Webb R. Clinton
Published: February 2006

Ca+-activated K+-channels (KCa) regulate vasomotor tone via smooth muscle hyperpolarization and relaxation. The relative contribution of the endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation differs depending on vessel type and size. It is unknown whether these KCachannels are differentially distributed along the same vascular bed and hence have different roles in mediating the EDHF response. We therefore assessed the role of small- (SKCa), intermediate- (IKCa), and large-conductance (BKCa) channels in mediating acetylcholine-induced relaxations in both first- and fourth-order side branches of the rat superior mesenteric artery (MA1 and MA4, respectively). Two-millimeter segments of each MA were mounted in the wire myograph, incubated with Nω-nitro-l-arginine methyl ester (l-NAME, 100 μmol/l) and indomethacin (10 μmol/l), and precontracted with phenylephrine (10 μmol/l). Cumulative concentration-response curves to ACh (0.001–10 μmol/l) were performed in the absence or presence of selective KCachannel antagonists. Apamin almost completely abolished these relaxations in MA4 but only partially blocked relaxations in MA1. The selective IKCachannel blocker 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34) caused a significantly greater inhibition of the ACh-induced relaxation in MA4 compared with MA1. Iberiotoxin had no inhibitory effect in MA4 but blunted relaxation in MA1. Relative mRNA expression levels of SKCa(rSK1, rSK3, and rSK4 = rIK1) were significantly higher in MA4 compared with MA1. BKCa(rBKα1and rBKβ1) genes were similar in both MA1 and MA4. Our data demonstrate regional heterogeneity in SKCaand IKCafunction and gene expression and stress the importance of these channels in smaller resistance-sized arteries, where the role of EDHF is more pronounced.
NKG2D ligands are expressed on stressed human airway epithelial cells
Authors: Borchers Michael T. , Harris Nathaniel L. , Wesselkamper Scott C. , Vitucci Mark , Cosman David
Published: February 2006

Immune surveillance of the airways is critical to maintain the integrity and health of the lung. We have identified a family of ligands expressed on the surface of stressed airway epithelial cells whose function is to bind the NKG2D-activating receptor found on several pulmonary lymphocytes, including natural killer cells, γδ+ T cells, and CD8+ T cells. We employed real-time PCR and flow cytometry in normal and transformed airway epithelial cell to demonstrate that major histocompatibility complex class I chain-related (MIC) B and the UL-16 binding protein (ULBP) ligands (ULBP1–4) are ubiquitously expressed at the mRNA level in all cell lines. MICA/B surface expression was present on 70% of transformed cell lines but was undetectable on primary cells. We demonstrate that MICA/B and ULBP 1, 2, 3, and 4 expression is rare or absent on the cell surface of unstimulated normal human bronchial epithelial cells although transcripts and intracellular proteins are present. Normal human bronchial epithelial cells exposed to 0.3 mM hydrogen peroxide exhibit an induction of all ligands examined on the cell surface. Surface expression is independent of changes in transcript level or total cellular protein and is mediated by the ERK family of mitogen-activated protein kinases. The induction of NKG2D ligands on stressed airway epithelial cells represents a potentially important mechanism of immune cell activation in regulation of pulmonary health and disease.
COX-2-derived prostacyclin protects against bleomycin-induced pulmonary fibrosis
Authors: Lovgren Alysia Kern , Jania Leigh A. , Hartney John M. , Parsons Kelly K. , Audoly Laurent P. , FitzGerald Garret A. , Tilley Stephen L. , Koller Beverly H.
Published: February 2006

Prostacyclin is one of a number of lipid mediators elaborated from the metabolism of arachidonic acid by the cyclooxygenase (COX) enzymes. This prostanoid is a potent inhibitor of platelet aggregation, and its production by endothelial cells and protective role in the vasculature are well established. In contrast, much less is known regarding the function of this prostanoid in other disease processes. We show here that COX-2-dependent production of prostacyclin plays an important role in the development of fibrotic lung disease, limiting both the development of fibrosis and the consequential alterations in lung mechanics. In stark contrast, loss of prostaglandin E2synthesis and signaling through the Gs-coupled EP2 and EP4 receptors had no effect on the development of disease. These findings suggest that prostacyclin analogs will protect against bleomycin-induced pulmonary fibrosis in COX-2−/−mice. If such protection is observed, investigation of these agents as a novel therapeutic approach to pulmonary fibrosis in humans may be warranted.
Patched1 Functions as a Gatekeeper by Promoting Cell Cycle Progression
Authors: Adolphe Christelle , Hetherington Rehan , Ellis Tammy , Wainwright Brandon
Published: February 2006

Mutations in the Hedgehog receptor, Patched 1 (Ptch1), have been linked to both familial and sporadic forms of basal cell carcinoma (BCC), leading to the hypothesis that loss of Ptch1 function is sufficient for tumor progression. By combining conditional knockout technology with the inducible activity of the Keratin6 promoter, we provide in vivo evidence that loss of Ptch1 function from the basal cell population of mouse skin is sufficient to induce rapid skin tumor formation, reminiscent of human BCC. Elimination of Ptch1 does not promote the nuclear translocation of β-catenin and does not induce ectopic activation or expression of Notch pathway constituents. In the absence of Ptch1, however, a large proportion of basal cells exhibit nuclear accumulation of the cell cycle regulators cyclin D1 and B1. Collectively, our data suggest that Ptch1 likely functions as a tumor suppressor by inhibiting G1-S phase and G2-M phase cell cycle progression, and the rapid onset of tumor progression clearly indicates Ptch1 functions as a “gatekeeper.” In addition, we note the high frequency and rapid onset of tumors in this mouse model makes it an ideal system for testing therapeutic strategies, such as Patched pathway inhibitors. (Cancer Res 2006; 66(4): 2081-8)
The Homeoprotein Six1 Transcriptionally Activates Multiple Protumorigenic Genes but Requires Ezrin to Promote Metastasis
Authors: Yu Yanlin , Davicioni Elai , Triche Timothy J. , Merlino Glenn
Published: February 2006

The vast majority of deaths associated with cancer are a consequence of a complex phenotypic behavior, metastasis, by which tumor cells spread from their primary site of origin to regional and distant sites. This process requires the tumor cell to make numerous adjustments, both subtle and dramatic, to successfully reach, survive, and flourish at favorable secondary sites. It has been suggested that molecular mechanisms accounting for metastatic behavior can recapitulate those employed during embryogenesis. We have shown that the homeodomain transcription factor Six1, known to be required for normal development of migratory myogenic progenitor cells, is sufficient to promote metastatic spread in a mouse model of the pediatric skeletal muscle cancer rhabdomyosarcoma. Here, we report that Six1 is able to activate the expression of a set of protumorigenic genes (encoding cyclin D1, c-Myc, and Ezrin) that can control cell proliferation, survival, and motility. Although the role of Ezrin in cytoskeletal organization and adhesion has been well studied, the means by which its expression is regulated are poorly understood. We now show that the gene encoding Ezrin is a direct transcriptional target of Six1. Moreover, Ezrin is indispensable for Six1-induced metastasis and highly expressed in a panel of representative pediatric cancers. Our data indicate that Ezrin represents a promising therapeutic target for patients with advanced-stage rhabdomyosarcoma and perhaps other malignancies. (Cancer Res 2006; 66(4): 1982-9)
Melanosomal Targeting Sequences from gp100 Are Essential for MHC Class II–Restricted Endogenous Epitope Presentation and Mobilization to Endosomal Compartments
Authors: Lepage Stéphanie , Lapointe Réjean
Published: February 2006

CD4+ T lymphocytes play an important role in CD8+ T cell–mediated responses against tumors. Considering that ∼20% of melanomas express MHC class II, it is plausible that concomitant presentation by MHC class I and class II shapes positive (helper T cells) or negative (regulatory T cells) antitumor responses. Interestingly, gp100, a melanoma antigen, can be presented by both MHC class I and class II when expressed endogenously, suggesting that it can reach endosomal/MHC class II compartments (MIIC). Here, we showed that gp100 putative NH2-terminal signal sequence and the last 70 residues in COOH terminus are essential for MIIC localization and MHC class II presentation. Confocal microscopy analyses confirmed that gp100 was localized in LAMP-1+/HLA-DR+ endosomal/MIIC. Gp100 targeting sequences were characterized by deleting different sections in the COOH terminus (last 70 residues). Transfection in 293T cells, expressing MHC class I and class II molecules, revealed that specific deletions in COOH terminus resulted in decreased MHC class II presentation, without effects on class I presentation, suggesting a role in MIIC trafficking for these deleted sections. Then, we used these gp100 targeting sequences to mobilize green fluorescent protein to endosomal compartments and to allow MHC class II and class I presentation of minimal endogenous epitopes. We conclude that these specific sequences are MIIC-targeting motifs, which could be included in expression cassettes for endogenously expressed tumor or viral antigens for MHC class II and class I presentation and optimize in vivo T-cell responses or as an in vitro tool for characterization of new MHC class II epitopes. (Cancer Res 2006; 66(4): 2423-32)
BRCA1 DNA-Binding Activity Is Stimulated by BARD1
Authors: Simons Amanda M. , Horwitz Andrew A. , Starita Lea M. , Griffin Karen , Williams R. Scott , Glover J.N. Mark , Parvin Jeffrey D.
Published: February 2006

The breast- and ovarian-specific tumor suppressor BRCA1 has been implicated in numerous cellular processes, including transcription, ubiquitination, and DNA repair. Its tumor suppression activity is tightly linked to that of BARD1, a protein that heterodimerizes with BRCA1. It has been previously shown that BRCA1 binds to DNA, an interesting functional observation in light of the genetic data linking BRCA1 to DNA repair pathways. In this work, we reexamine the DNA-binding properties of BRCA1, comparing them with the DNA-binding properties of the BRCA1/BARD1 heterodimer. Because nuclear BRCA1 exists as a heterodimer with BARD1, it is likely that in vitro studies of the heterodimer will provide a more accurate model of physiologic conditions. Our results indicate that whereas BARD1 cannot directly bind DNA, it does enhance DNA binding by BRCA1. This is a surprising observation as both DNA-binding domains are distal to the BARD1-interacting RING domain of BRCA1. Further analysis of the dimerization reveals that the BRCA1/BARD1 interaction is not limited to the amino-terminal RING domains of each protein. The carboxyl terminus of BRCA1 contributes significantly to the stability of the heterodimer. We also show that the presence of BARD1 has a secondary effect, as autoubiquitination of BRCA1/BARD1 heterodimers additionally enhances the affinity of BRCA1 for DNA. Together, these data suggest that BRCA1 and BARD1 heterodimerization is stabilized via domains not previously thought to interact and that BARD1 acts in both ubiquitination-dependent and ubiquitination-independent ways to influence the role of BRCA1 in DNA repair. (Cancer Res 2006; 66(4): 2012-8)
Association between Plasma Prolactin Concentrations and Risk of Breast Cancer among Predominately Premenopausal Women
Authors: Tworoger Shelley S. , Sluss Patrick , Hankinson Susan E.
Published: February 2006

Recent evidence suggests that prolactin may be positively associated with postmenopausal breast cancer risk; however, little data are available in younger women. Therefore, we conducted a prospective, nested case-control study to examine the relationship between plasma prolactin concentrations and breast cancer risk in predominately premenopausal women from the Nurses' Health Study II. Blood samples were collected from 1996 to 1999. The analysis includes 316 cases of breast cancer diagnosed after blood donation and before June 1, 2003, who had two controls matched on age, fasting status, time of day and month of blood collection, race/ethnicity, and timing of blood draw within the menstrual cycle. Sixty-three percent of participants provided a timed follicular and luteal menstrual phase blood sample; other women provided a single untimed sample. When including all women, we observed a positive association between prolactin and breast cancer risk [relative risk (RR), top quartile versus bottom quartile, 1.5; 95% confidence interval (95% CI), 1.0-2.3; Ptrend = 0.03] that was slightly stronger among estrogen receptor–positive/progesterone receptor–positive tumors (comparable RR, 1.9; 95% CI, 1.1-3.3; Ptrend = 0.04). Associations were similar among premenopausal women only. However, we did not find an association between prolactin and breast cancer risk among the subset of women who only provided timed samples (comparable RR, average of timed samples, 1.3; 95% CI, 0.8-2.3; Ptrend = 0.40). The association seemed stronger among women ≥45 years old and for cases diagnosed within ∼4 years of blood collection. Our data suggest a modest positive association between prolactin and breast cancer risk among predominately premenopausal women; however, further follow-up is needed to increase power for subgroup analyses. (Cancer Res 2006; 66(4): 2476-82)
Cooperation between FGF8b Overexpression and PTEN Deficiency in Prostate Tumorigenesis
Authors: Zhong Chen , Saribekyan Gohar , Liao Chun-Peng , Cohen Michael B. , Roy-Burman Pradip
Published: February 2006

Two commonly occurring genetic aberrations of human prostate cancer [i.e., overexpression of a mitogenic polypeptide (fibroblast growth factor 8, isoform b or FGF8b) and loss of function of PTEN tumor suppressor] were recapitulated into a new combinatorial mouse model. This model harboring the Fgf8b transgene and haploinsufficiency in Pten, both in a prostate epithelium–specific manner, yielded prostatic adenocarcinoma with readily detectable lymph node metastases, whereas single models with each of the defects were shown earlier to progress generally only up to prostatic intraepithelial neoplasia (PIN). In addition to late age-related development of typical adenocarcinoma, the model also displayed a low incidence of mucinous adenocarcinoma, a rare variant type of human prostatic adenocarcinoma. The cooperation between FGF8b activation and PTEN deficiency must be linked to acquisition of additional genetic alterations for the progression of the lesions to primary adenocarcinoma. Here, we identified loss of heterozygosity at the Pten gene leading to bialleic loss, as a necessary secondary event, indicating that a complete loss of PTEN function is required in the development of invasive cancer in the model. Analyses of expression of downstream mediators phospho-AKT (p-AKT) and p27KIP1, in various types of lesions, however, revealed a complex picture. Although PIN lesions displayed relatively strong expression of p-AKT and p27KIP1, there was a notable heterogeneity with variable decrease in their immunostaining in adenocarcinomas. Together, the results further underscore the notion that besides activation of AKT by loss of PTEN function, other PTEN-regulated pathways must be operative for progression of lesions from PIN to adenocarcinoma. (Cancer Res 2006; 66(4): 2188-94)
The Novel Tumor Suppressor p33ING2 Enhances Nucleotide Excision Repair via Inducement of Histone H4 Acetylation and Chromatin Relaxation
Authors: Wang Jing , Chin Mei Yieng , Li Gang
Published: February 2006

p33ING2 is a novel candidate tumor suppressor, which has been shown to be involved in the regulation of gene transcription, cell cycle arrest, and apoptosis in a p53-dependent manner for maintaining the genomic stability. Previously, we showed that p33ING2 promoted UV-induced apoptosis in human melanoma cells. To further reveal the role of p33ING2 in cellular stress response to UV irradiation, we hypothesized that p33ING2 may enhance the repair of UV-damaged DNA, similarly to its homologue p33ING1b. Using the host-cell reactivation assay, we show that overexpression of p33ING2 significantly enhances nucleotide excision repair of UV-induced DNA damage in melanoma cells in a p53-dependent manner. Furthermore, DNA repair is completely abolished in cells treated with p33ING2 small interfering RNA, suggesting that a physiologic level of p33ING2 is required for nucleotide excision repair. In addition, we found that p33ING2 is an essential factor for UV-induced rapid histone H4 acetylation, chromatin relaxation, and the recruitment of damage recognition protein, xeroderma pigmentosum group A protein, to the photolesions. These observations suggest that p33ING2 is required for the initial DNA damage sensing and chromatin remodeling in the nucleotide excision repair process. (Cancer Res 2006; 66(4): 1906-11)
Multiple Hepatic Receptors Cooperate to Eliminate Secretory Mucins Aberrantly Entering the Bloodstream: Are Circulating Cancer Mucins the “Tip of the Iceberg”?
Authors: Wahrenbrock Mark G. , Varki Ajit
Published: February 2006

Hollow organs lined by columnar epithelial cells normally secrete mucins and their proteolytic fragments vectorially into the lumen. These heterogeneously O-glycosylated molecules are known to aberrantly enter the bloodstream in the setting of epithelial carcinomas and possibly during injury or inflammation. We have recently shown that carcinoma mucin fragments can trigger the rapid formation of platelet-rich microthrombi in vivo. Thus, mechanisms to clear such aberrantly secreted mucins must exist. Indeed, we found that i.v. injected carcinoma mucin fragments had an ∼1 minute half-life in mice, which was primarily due to rapid clearance by hepatic reticuloendothelial cells. Inhibition of known glycan-recognizing hepatic clearance receptors showed involvement of multiple partially overlapping clearance systems. Studies of genetically deficient mice and incomplete competition between different mucins confirmed this result. Thus, multiple hepatic clearance receptors cooperate to eliminate secretory mucins entering the circulation, limiting potential pathology. This may also explain why mucin-type clustered O-glycosylation is rare on plasma proteins. Notably, small subsets of injected carcinoma mucins remained unrecognized by clearance systems, had a much longer half-life, and carried highly sialylated O-glycans. Similar circulating mucins were found in tumor-bearing mice despite lack of saturation of hepatic clearance mechanisms. Thus, circulating cancer mucins currently used as clinical diagnostic markers likely represent only the clearance-resistant “tip of the iceberg.” Such aberrantly circulating mucins could play pathologic roles not only in cancer but also during injury or inflammation of hollow organs and in liver disease. (Cancer Res 2006; 66(4): 2433-41)
Molecular Dissection of Angiotensin II–Activated Human LOX-1 Promoter
Authors: Chen Jiawei , Liu Yong , Liu Hongmei , Hermonat Paul L. , Mehta Jawahar L.
Published: February 2006

Objective—

LOX-1, a receptor for oxidized low-density lipoprotein, plays a critical role in atherosclerosis. Its expression is upregulated by pro-atherogenic stimuli, such as angiotensin II (Ang II). In this study, we explored LOX-1 transcriptional promoter activation in response to Ang II in human coronary artery endothelial cells (HCAECs).

Methods and Results—

We constructed full-length and deletion LOX-1 promoter mutants and examined their activation in response to Ang II in HCAECs. The Ang II (1 μmol/L for 24 hours) markedly induced LOX-1 promoter activity beyond the basal level, and a 116-bp fragment (between nt −2247 and −2131) was necessary for this induction. Within this 116-bp promoter fragment, there is a potential binding motif for transcription factor NF-κB. By EMSA, we observed the activation of NF-κB by Ang II. The critical role of NF-κB in Ang II–induced LOX-1 promoter activation was confirmed by mutagenesis assay, and further confirmed by blocking NF-κB activation with the NF-κB inhibitor caffeic acid phenethyl ester or NF-κB p65 siRNA.

Conclusion—

This study strongly suggests that Ang II, by activating NF-κB, induces LOX-1 promoter activation.
Minimally Oxidized LDL Offsets the Apoptotic Effects of Extensively Oxidized LDL and Free Cholesterol in Macrophages
Authors: Boullier Agnès , Li Yankun , Quehenberger Oswald , Palinski Wulf , Tabas Ira , Witztum Joseph L. , Miller Yury I.
Published: February 2006

Objective—

Lipid-loaded macrophage-derived foam cells populate atherosclerotic lesions and produce many pro-inflammatory and plaque-destabilizing factors. An excessive accumulation of extensively oxidized low-density lipoprotein (OxLDL) or free cholesterol (FC), both of which are believed to be major lipid components of macrophages in advanced lesions, rapidly induces apoptosis in macrophages. Indeed, there is evidence of macrophage death in lesions, but how the surviving macrophages avoid death induced by OxLDL, FC, and other factors is not known.

Methods and Results—

Minimally oxidized LDL (mmLDL), which is an early product of progressive LDL oxidation in atherosclerotic lesions, countered OxLDL-induced or FC-induced apoptosis and stimulated macrophage survival both in cell culture and in vivo. DNA fragmentation and caspase-3 activity in OxLDL-treated peritoneal macrophages were significantly reduced by coincubation with mmLDL. In a separate set of experiments, mmLDL significantly reduced annexin V binding to macrophages in which apoptosis was induced by FC loading. In both cellular models, mmLDL activated a pro-survival PI3K/Akt signaling pathway, and PI3K inhibitors, wortmannin and LY294002, eliminated the pro-survival effect of mmLDL. Immunohistochemical examination demonstrated phospho-Akt in murine atherosclerotic lesions.

Conclusions—

Minimally oxidized LDL, an early form of oxidized LDL in atherosclerotic lesions, may contribute to prolonged survival of macrophage foam cells in lesions via a PI3K/Akt-dependent mechanism.
Dietary Factors That Promote or Retard Inflammation
Authors: Basu Arpita , Devaraj Sridevi , Jialal Ishwarlal
Published: February 2006

Inflammation plays a pivotal role in all stages of atherosclerosis. Cardiovascular risk factors and metabolic syndrome are typified by low-grade inflammation. Intervention trials convincingly demonstrate that weight loss reduces biomarkers of inflammation, such as C-reactive protein (CRP) and interleukin (IL)-6. Limited studies have shown that certain dietary factors; oleic acid, α-linolenic acid, and antioxidants RRR-α-alpha tocopherol, reduce biomarkers of inflammation. Most of the studies with fish oil supplementation have shown null effects, and conflicting results have been reported with saturated and
trans
fatty acids, cholesterol, and soy intake. Much further research is needed to define the role of individual dietary factors on the biomarkers of inflammation and the mechanism of the anti-inflammatory effects of weight loss.
No Apparent Requirement for Neuronal Sodium Channels in Excitation-Contraction Coupling in Rat Ventricular Myocytes
Authors: Brette Fabien , Orchard Clive H.
Published: February 2006

The majority of Na channels in the heart are composed of the tetrodotoxin (TTX)-resistant (K
D
, 2 to 6 μmol/L) “cardiac” Na
V
1.5 isoform; however, TTX-sensitive (K
D
, 1 to 25 nmol/L) “neuronal” Na channel isoforms have recently been detected in several cardiac preparations. In the present study, we determined the functional subcellular localization of Na channel isoforms (according to their TTX sensitivity) in rat ventricular myocytes by recording
I
Na
in control and detubulated myocytes. We found that TTX-sensitive
I
Na
(K
D
, &8.8 nmol/L) makes up 14±3% of total
I
Na
in control and ≤4% in detubulated myocytes and calculated that &80% of TTX-sensitive
I
Na
is located in the t-tubules, where it generates &1/3 of t-tubular
I
Na
. In contrast, TTX-resistant
I
Na
is located predominantly (&78%) at the surface membrane. We also investigated the possible contribution of TTX-sensitive
I
Na
to excitation-contraction coupling, using 200 nmol/L TTX to selectively block TTX-sensitive
I
Na
. TTX decreased the rate of depolarization of the action potential by 10% but did not delay the rise of systolic Ca
2+
in the center of the cell (transverse confocal line scan), suggesting that TTX-sensitive
I
Na
does not play a role in synchronizing Ca
2+
release at the t-tubules; the amplitude of the Ca
2+
transient and contraction were also unchanged by 200 nmol/L TTX. The quantity of charge entering via
I
Ca
elicited by control or TTX action potential waveforms was similar, suggesting that the trigger for Ca
2+
release is not altered by blocking TTX-sensitive
I
Na
. We conclude that neuronal
I
Na
is concentrated at the t-tubules, but there is no evidence of a requirement for these channels in normal excitation-contraction coupling in ventricular myocytes.