bluuebunny/crossref_metadata_2025 huggingface dataset:
‘Love's Interest’: Agency and Identity in a Seventeenth‐Century Nun's Letters
Authors: Pfannebecker Mareile
Published: February 2006

This essay won the 2005 Literature Compass Graduate Essay Prize, Seventeenth Century Section.

In studies of seventeenth‐century women's writing, emphasis has recently shifted from the more traditional literary canon to investigations of ‘non‐literary’ manuscript text. As James Daybell notes, the vast majority of texts authored by early modern women are letters (161). Many of these letters explicitly engage with religious matters or are pervaded by the religiosity of the speaker. Winefrid Thimelby, a recusant Englishwoman who became a nun and lived at an English convent in France throughout much of the Civil War and Restoration, is one of these letter‐writers. In this paper, I argue that not despite, but because of her religious seclusion, Thimelby's letters facilitate her engagement in power relations outside convent walls. In this context, the self‐construction of the letter‐writer is examined with reference to Stephen Greenblatt's notion of self‐fashioning.
Properties of ivabradine‐induced block of HCN1 and HCN4 pacemaker channels
Authors: Bucchi A. , Tognati A. , Milanesi R. , Baruscotti M. , DiFrancesco D.
Published: February 2006

Ivabradine is a ‘heart rate‐reducing’ agent able to slow heart rate, without complicating side‐effects. Its action results from a selective and specific block of pacemaker f‐channels of the cardiac sinoatrial node (SAN). Investigation has shown that block by ivabradine requires open f‐channels, is use dependent, and is affected by the direction of current flow. The constitutive elements of native pacemaker channels are the hyperpolarization‐activated cyclic nucleotide‐gated (HCN) channels, of which four isoforms (HCN1–4) are known; in rabbit SAN tissue HCN4 is expressed strongly, and HCN1 weakly. In this study we have investigated the blocking action of ivabradine on mouse (m) HCN1 and human (h) HCN4 channels heterologously expressed in HEK 293 cells. Ivabradine blocked both channels in a dose‐dependent way with half‐block concentrations of 0.94 μm for mHCN1 and 2.0 μm for hHCN4. Properties of block changed substantially for the two channels. Block of hHCN4 required open channels, was strengthened by depolarization and was relieved by hyperpolarization. Block of mHCN1 did not occur, nor was it relieved, when channels were in the open state during hyperpolarization; block required channels to be either closed, or in a transitional state between open and closed configurations. The dependence of block upon current flow was limited for hHCN4, and not significant for mHCN1 channels. In summary our results indicate that ivabradine is an ‘open‐channel’ blocker of hHCN4, and a ‘closed‐channel’ blocker of mHCN1 channels. The mode of action of ivabradine on the two channels is discussed by implementing a simplified version of a previously developed model of f‐channel kinetics.
Exercise increases SOCS‐3 expression in rat skeletal muscle: potential relationship to IL‐6 expression
Authors: Spangenburg Espen E. , Brown David A. , Johnson Micah S. , Moore Russell L.
Published: February 2006

Suppressor of cytokine signalling‐3 (SOCS‐3) has been implicated in the onset of insulin resistance in non‐muscle tissue. Thus, we examined the effects of exercise training on SOCS‐3 expression and the potential role of SOCS‐3 in muscle. Female Sprague‐Dawley rats (5–8 months) were treadmill trained for 12 weeks and the muscles were removed 24 h after the last bout of exercise. Exercise training increased SOCS‐3 mRNA expression by 80% and 154% in the plantaris and soleus muscle, respectively. To mimic the effects of increased SOCS‐3 expression, SOCS‐3 cDNA was cotransfected with a NF‐kappa B (NF‐κB) luciferase construct into cultured C2C12 myotubes. SOCS‐3 overexpression increased NF‐κB transcriptional activity by 27‐fold. The proximal region of the IL‐6 gene promoter contains a NF‐κB consensus site, which contributes to increased IL‐6 expression in various tissues. SOCS‐3 cDNA was cotransfected into cultured C2C12 myotubes with either the IL‐6 luciferase construct or a mutated NF‐κB IL‐6 luciferase construct. SOCS‐3 overexpression increased IL‐6 transcriptional activity by 15‐fold, however, when the NF‐κB site was mutated SOCS‐3 failed to increase IL‐6 transcriptional activity. We subsequently found that IL‐6 mRNA expression was elevated in the plantaris and soleus muscles of the trained animals compared to the sedentary animals. Finally, exercise induced a significant reduction in IκBα and increased phosphorylation of Iκκ suggesting that NF‐κB activation was elevated after exercise training. These data suggest that training‐induced elevations in SOCS‐3 expression in skeletal muscle may contribute to the exercise‐induced increase in IL‐6 expression through alterations in the mechanisms that mediate NF‐κB activity.
Relationship between evolving epileptiform activity and delayed loss of mitochondrial activity after asphyxia measured by near‐infrared spectroscopy in preterm fetal sheep
Authors: Bennet L. , Roelfsema V. , Pathipati P. , Quaedackers J. S. , Gunn A. J.
Published: February 2006

Early onset cerebral hypoperfusion after birth is highly correlated with neurological injury in premature infants, but the relationship with the evolution of injury remains unclear. We studied changes in cerebral oxygenation, and cytochrome oxidase (CytOx) using near‐infrared spectroscopy in preterm fetal sheep (103–104 days of gestation, term is 147 days) during recovery from a profound asphyxial insult (n= 7) that we have shown produces severe subcortical injury, or sham asphyxia (n= 7). From 1 h after asphyxia there was a significant secondary fall in carotid blood flow (P < 0.001), and total cerebral blood volume, as reflected by total haemoglobin (P < 0.005), which only partially recovered after 72 h. Intracerebral oxygenation (difference between oxygenated and deoxygenated haemoglobin concentrations) fell transiently at 3 and 4 h after asphyxia (P < 0.01), followed by a substantial increase to well over sham control levels (P < 0.001). CytOx levels were normal in the first hour after occlusion, was greater than sham control values at 2–3 h (P < 0.05), but then progressively fell, and became significantly suppressed from 10 h onward (P < 0.01). In the early hours after reperfusion the fetal EEG was highly suppressed, with a superimposed mixture of fast and slow epileptiform transients; overt seizures developed from 8 ± 0.5 h. These data strongly indicate that severe asphyxia leads to delayed, evolving loss of mitochondrial oxidative metabolism, accompanied by late seizures and relative luxury perfusion. In contrast, the combination of relative cerebral deoxygenation with evolving epileptiform transients in the early recovery phase raises the possibility that these early events accelerate or worsen the subsequent mitochondrial failure.
PGE2 glycerol ester, a COX‐2 oxidative metabolite of 2‐arachidonoyl glycerol, modulates inhibitory synaptic transmission in mouse hippocampal neurons
Authors: Sang Nan , Zhang Jian , Chen Chu
Published: February 2006

The oxygenation of endogenous cannabinoids (eCBs) 2‐arachidonoyl glycerol (2‐AG) and arachidonoyl ethanolamide by cyclooxygenase‐2 (COX‐2) produces novel types of prostanoids: prostaglandin glycerol esters (PG‐Gs) and prostaglandin ethanolamides (PG‐EAs). However, the physiological function of COX‐2 oxidative metabolites of eCBs is still unclear. Here we demonstrate that PGE2‐G, a COX‐2 oxidative metabolite of 2‐AG, induced a concentration‐dependent increase in the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in primary cultured hippocampal neurons, an effect opposite to that of 2‐AG. This increase was not inhibited by SR141716, a CB1 receptor antagonist, but was attenuated by an IP3 or MAPK inhibitor. In addition, we also examined the effects of other prostanoids derived from COX‐2 oxygenation of eCBs on mIPSCs. PGD2‐G, PGF2α‐G and PGD2‐EA, but not PGE2‐EA or PGF2α‐EA, also increased the frequency of mIPSCs. The eCB‐derived prostanoid‐induced responses appeared to be different from those of corresponding arachidonic acid‐derived prostanoids, implying that these effects are not mediated via known prostanoid receptors. We further discovered that the inhibition of COX‐2 activity reduced inhibitory synaptic activity and augmented depolarization‐induced suppression of inhibition (DSI), whereas the enhancement of COX‐2 augmented the synaptic transmission and abolished DSI. Our results, which show that COX‐2 oxidative metabolites of eCBs exert opposite effects to their parent molecules on inhibitory synaptic transmission, suggest that alterations in COX‐2 activity will have significant impact on endocannabinoid signalling in hippocampal synaptic activity.
Differential effects of contraction and PPAR agonists on the expression of fatty acid transporters in rat skeletal muscle
Authors: Benton Carley R. , Koonen Debby P. Y. , Calles‐Escandon Jorge , Tandon Narendra N. , Glatz Jan F. C. , Luiken Joost J. F. P. , Heikkila John J. , Bonen Arend
Published: February 2006

We have examined over the course of a 1‐week period the independent and combined effects of chronically increased muscle contraction and the peroxisome proliferator‐activated receptor (PPAR)α and PPARγ activators, Wy 14,643 and rosiglitazone, on the expression and plasmalemmal content of the fatty acid transporters, FAT/CD36 and FABPpm, as well as on the rate of fatty acid transport. In resting muscle, the activation of either PPARα or PPARγ failed to induce the protein expression of FAT/CD36. PPARα activation also failed to induce the protein expression of FABPpm. In contrast, PPARγ activation induced the expression of FABPpm protein (40%; P < 0.05). Chronic muscle contraction increased the protein expression of FAT/CD36 (∼50%; P < 0.05), whereas FABPpm was slightly increased (12%; P < 0.05). Neither PPARα nor PPARγ activation altered the contraction‐induced expression of FAT/CD36 or FABPpm. Changes in protein expression of FAT/CD36 or FABPpm, induced by either contractions or by administration of rosiglitazone, were largely attributable to increased transcription. The contraction‐induced increments in FAT/CD36 were accompanied by parallel increments in plasmalemmal FAT/CD36 and in rates of fatty acid transport (P < 0.05). Up‐regulation of FABPpm expression was, however, accompanied by a reduction in plasmalemmal FABPpm, which did not affect the rates of long chain fatty acid (LCFA) transport. These studies have shown that in skeletal muscle (i) neither PPARα nor PPARγ activation alters FAT/CD36 expression, (ii) PPARγ activation selectively up‐regulates FABPpm expression and (iii) contraction‐induced up‐regulation of LCFA transport does not appear to occur via activation of either PPARα or PPARγ.
Ultrafast Laser-Driven Microlens to Focus and Energy-Select Mega-Electron Volt Protons
Authors: Toncian Toma , Borghesi Marco , Fuchs Julien , d'Humières Emmanuel , Antici Patrizio , Audebert Patrick , Brambrink Erik , Cecchetti Carlo Alberto , Pipahl Ariane , Romagnani Lorenzo , Willi Oswald
Published: February 2006

We present a technique for simultaneous focusing and energy selection of high-current, mega–electron volt proton beams with the use of radial, transient electric fields (10
7
to 10
10
volts per meter) triggered on the inner walls of a hollow microcylinder by an intense subpicosecond laser pulse. Because of the transient nature of the focusing fields, the proposed method allows selection of a desired range out of the spectrum of the polyenergetic proton beam. This technique addresses current drawbacks of laser-accelerated proton beams, such as their broad spectrum and divergence at the source.
Early integration of high copy HPV16 detectable in women with normal and low grade cervical cytology and histology
Authors: Kulmala S-M A , Syrjänen S M , Gyllensten U B , Shabalova I P , Petrovichev N , Tosi P , Syrjänen K J , Johansson B C
Published: February 2006

Background:Integration of human papillomavirus (HPV) DNA has been considered a late event in cervical carcinogenesis. However, integrated forms of HPV were recently detected in cancer precursor lesions using a new real time polymerase chain reaction (PCR) to detect the deletions at the 3362–3443 region of HPV16 E2

Objective:To study the frequency of HPV16 DNA integration in cervical lesions and compare the sensitivity of an additional upstream region of the E2 ORF (2962–3138) in detecting HPV integration.

Methods:Using the TaqMan based PCR, HPV16 positive DNA samples were analysed in 164 cervical scrapings from women participating in a multicentre screening trial. Biopsy confirmation was available in 62 cases.

Results:Primers targeting the 3362–3443 region detected the majority of E2 deletions. In only 23% of the samples was the E2 upstream region equal or better target than the 3362–3443 region. Mixed (episomal/integrated) pattern was the most prevalent physical state of HPV16, also present in PAP smears with normal morphology. Pure integrated form was most prevalent in HSIL and cancer lesions, but also detectable in low grade abnormalities (NSIL, ASC-US, LSIL). Women with only integrated HPV16 were almost 10 years older than those with episomal HPV16. Viral load of integrated HPV16 was related to cytological abnormality (p = 0.003) but not to histology.

Conclusions:Integrated HPV16 is present in low grade cervical lesions, mostly mixed with the episomal form. Women with the pure integrated form of HPV16 are older than those with the other forms.
Designing LC VCOs Using Capacitive Degeneration Techniques
Authors: Jung Byunghoo , Harjani Ramesh
Published: February 2006

In this paper, we present a detailed analysis of VCOs using a capacitively degenerated negative resistance cell. The negative resistance cell using capacitive degeneration has a higher maximum attainable oscillation frequency and a smaller equivalent shunt capacitance when compared to the widely used cross-coupled negative-gm cell. These properties are of particular interest for the design of high-frequency and/or wide tuning range VCOs. The negative resistance provided by a traditional capacitively degenerated negative resistance cell is lower than that provided by a cross-coupled negative-gm cell. We present an active capacitive degeneration topology that overcomes this limitation. To validate this circuit topology we use two test vehicles. The first test vehicle is a 5.3 GHz VCO designed in a 0.25 μm CMOS technology and the second test vehicle is a 20 GHz VCO designed in a 0.25 μm BiCMOS technology. Measurement and simulation results from both test vehicles effectively demonstrate the efficacy of the capacitive degeneration technique.
LOW-POWER, PARALLEL INTERFACE WITH CONTINUOUS-TIME ADAPTIVE PASSIVE EQUALIZER AND CROSSTALK CANCELLATION
Authors: YUE C. PATRICK , PARK JAEJIN , SUN RUIFENG , CARLEY L. RICK , O'MAHONY FRANK
Published: February 2006

This paper presents the low-power circuit techniques suitable for high-speed digital parallel interfaces each operating at over 10 Gbps. One potential application for such high-performance I/Os is the interface between the channel IC and the magnetic read head in future compact hard disk systems. First, a crosstalk cancellation technique using a novel data encoding scheme is introduced to suppress electromagnetic interference (EMI) generated by the adjacent parallel I/Os . This technique is implemented utilizing a novel 8-4-PAM signaling with a data look-ahead algorithm. The key circuit components in the high-speed interface transceiver including the receive sampler, the phase interpolator, and the transmitter output driver are described in detail. Designed in a 0.13-μm digital CMOS process, the transceiver consumes 310 mW per 10-Gps channel from a I-V supply based on simulation results. Next, a 20-Gbps continuous-time adaptive passive equalizer utilizing on-chip lumped RLC components is described. Passive equalizers offer the advantages of higher bandwidth and lower power consumption compared with conventional designs using active filter. A low-power, continuous-time servo loop is designed to automatically adjust the equalizer frequency response for the optimal gain compensation. The equalizer not only adapts to different channel characteristics, but also accommodates temperature and process variations. Implemented in a 0.25-μm, 1P6M BiCMOS process, the equalizer can compensate up to 20 dB of loss at 10 GHz while only consumes 32 mW from a 2.5-V supply.
ON THE QUARTIC HIGHER-DERIVATIVE GRAVITATIONAL TERMS IN THE HETEROTIC SUPERSTRING THEORY
Authors: POLLOCK M. D.
Published: February 2006

The quartic higher-derivative gravitational terms [Formula: see text] in the heterotic-superstring effective Lagrangian [Formula: see text], defined from the Riemann ten-tensor [Formula: see text], are expanded, after reduction to the conformally-flat physical D-space gij, in terms of the Ricci tensor Rij and scalar R. The resulting quadratic term [Formula: see text] is tachyon-free and agrees exactly with the prediction from global supersymmetry in the nonlinear realization of Volkov and Akulov of the flat-space, quadratic fermionic Lagrangian [Formula: see text] for a massless Dirac or Weyl spinor, only when D = 4, assuming the Einstein equation [Formula: see text] for the energy–momentum tensor. This proves that the heterotic superstring has to be reduced from ten to four dimensions if supersymmetry is to be correctly incorporated into the theory, and it rules out the bosonic string and type-II superstring, for which [Formula: see text] has the different a priori forms ±(R2-4RijRij) derived from [Formula: see text], which also contain tachyons (that seem to remain after the inclusion of a further contribution to [Formula: see text] from [Formula: see text]).

The curvature of space–time introduces a mass into the Dirac equation, [Formula: see text], while quadratic, higher-derivative terms [Formula: see text] make an additional contribution to the Einstein equations, these two effects causing a difference between [Formula: see text] and [Formula: see text] on the one hand, and the predictions from [Formula: see text] and [Formula: see text] on the other. The quartic terms [Formula: see text] still possess some residual symmetry, however, enabling us to estimate the radius-squared of the internal six-dimensional space [Formula: see text] in units of the Regge slope-parameter α′ as B r ≈ 1.75, indicating that compactification occurs essentially at the Planck era, due to quantum mechanical processes, when the action evaluated within the causal horizon is S h ~ 1. This symmetry is also discussed with regard to the zero-action hypothesis.

The dimensionality D = 4 of space–time is rederived from the Wheeler–DeWitt equation (Schrödinger equation) of quantum cosmology in the mini-superspace approximation, by demanding invariance and positive-semi-definiteness of the potential [Formula: see text] under Wick rotation of the time coordinate, which also determines the three-space to be flat, so that K = 0, and again involves the nonlinearity of gravitation.
SYMMETRIES AND PHYSICAL FUNCTIONS IN GENERAL GAUGE THEORY
Authors: GITMAN D. M. , TYUTIN I. V.
Published: February 2006

The aim of the present paper is to describe the symmetry structure of a general gauge (singular) theory, and, in particular, to relate the structure of gauge transformations with the constraint structure of a theory in the Hamiltonian formulation. We demonstrate that the symmetry structure of a theory action can be completely revealed by solving the so-called symmetry equation. We develop a corresponding constructive procedure of solving the symmetry equation with the help of a special orthogonal basis for the constraints. Thus, we succeed in describing all the gauge transformations of a given action. We find the gauge charge as a decomposition in the orthogonal constraint basis. Thus, we establish a relation between the constraint structure of a theory and the structure of its gauge transformations. In particular, we demonstrate that, in the general case, the gauge charge cannot be constructed with the help of some complete set of first-class constraints alone, because the charge decomposition also contains second-class constraints. The above-mentioned procedure of solving the symmetry equation allows us to describe the structure of an arbitrary symmetry for a general singular action. Finally, using the revealed structure of an arbitrary gauge symmetry, we give a rigorous proof of the equivalence of two definitions of physicality condition in gauge theories: one of them states that physical functions are gauge-invariant on the extremals, and the other requires that physical functions commute with FCC (the Dirac conjecture).
BOUND STATES OF THE KLEIN–GORDON EQUATION IN THE PRESENCE OF SHORT RANGE POTENTIALS
Authors: VILLALBA VÍCTOR M. , ROJAS CLARA
Published: February 2006

We solve the Klein–Gordon equation in the presence of a spatially one-dimensional cusp potential. The bound state solutions are derived and the antiparticle bound state is discussed.
HUNTING FOR SUPERSYMMETRY IN DARK MATTER ALLOWED REGIONS
Authors: BELYAEV ALEXANDER
Published: February 2006

Supersymmetry remains compelling theory over 30 years in spite of lack of its discovery. It might be somewhere near the corner at the present era of TeV energy colliders and sensitive dark matter search experiments which are crucial for constraining or even discovery of the supersymmetry.
GENERALIZED ENDOPRIMAL ABELIAN GROUPS
Authors: ALBRECHT U. , BREAZ S. , WICKLESS W.
Published: February 2006

An n-ary endofunction on an abelian group G is a function f : Gn → G such that f(θg1,…,θgn) = θ f(g1,…,gn) for all endomorphisms θ of G. A group G is endoprimal if, for each natural number n, each n-ary endofunction has the following simple form: [Formula: see text] for some collection of integers {li : 1 ≤ i ≤ n}. The notion of endoprimality arises from universal algebra in a natural way and has been applied to the study of abelian groups in papers Davey and Pitkethly (97), Kaarli and Marki (99) and Göbel, Kaarli, Marki, and Wallutis (to appear). These papers make the case that the notion of endoprimality can give rise to interesting and tractable classes of abelian groups. We continue working along these lines, adapting our definition to make it more suitable for working with general classes of abelian groups. We study generalized endoprimal (ge) abelian groups. Here every n-ary endofunction is required to be of the form [Formula: see text] for some collection of central endomorphisms {λi : 1 ≤ i ≤ n} of G. (Note that such a sum is always an endofunction.) We characterize generalized endoprimal abelian groups in a number of cases, in particular for torsion groups, torsion-free finite rank groups G such that E(G) has zero nil radical, and self-small mixed groups of finite torsion-free rank.
QUALITATIVE RESEARCH: Recent Developments in Case Study Methods
Authors: Bennett Andrew , Elman Colin
Published: February 2006

▪ Abstract  This article surveys the extensive new literature that has brought about a renaissance of qualitative methods in political science over the past decade. It reviews this literature's focus on causal mechanisms and its emphasis on process tracing, a key form of within-case analysis, and it discusses the ways in which case-selection criteria in qualitative research differ from those in statistical research. Next, the article assesses how process tracing and typological theorizing help address forms of complexity, such as path dependence and interaction effects. The article then addresses the method of fuzzy-set analysis. The article concludes with a call for greater attention to means of combining alternative methodological approaches in research projects.
REGULATING INFORMATION FLOWS: States, Private Actors, and E-Commerce
Authors: Farrell Henry
Published: February 2006

▪ Abstract  Growing interdependence between jurisdictions means that states are increasingly using private actors as proxies in order to achieve desired regulatory outcomes. International relations theory has had difficulty in understanding the exact circumstances under which they might wish to do this. Drawing on literatures in both international relations and legal scholarship, this article proposes a framework for understanding when states will or will not use private actors as proxy regulators. This framework highlights the relationship between state preferences and the presence or absence of a “point of control,” a special kind of private actor. The article then conducts an initial plausibility probe of the framework, assessing how well it explains outcomes in the regulation of gambling, privacy, and the taxation of e-commerce.
The Heart of the African Conflict Zone: Democratization, Ethnicity, Civil Conflict, and the Great Lakes Crisis
Authors: Young Crawford
Published: February 2006

▪ Abstract  In the 1990s, simultaneous with a wave of democratization that proved only partially successful, Africa was swept by protracted civil conflicts, which had a number of novel attributes. The Great Lakes region—Congo-Kinshasa, Rwanda, and Burundi—was the epicenter. In their dynamics and demographics, the violent combats became interpenetrated, embroiling the three countries in intractable struggles. Their extraordinary complexity, and multiplicity of state and other actors, interrogated a number of distinct literatures. State decay and collapse, a broader phenomenon in Africa, was especially marked in Congo-Kinshasa. In all three countries, the irresistible pressures for democratization—which were part of a broader African pattern—triggered violent struggles over definitions of identity, citizenship, and indigeneity. The legal, moral, and analytical issue of genocide returned to the research agenda with a vengeance with the Rwandan catastrophe in 1994, and mass ethnic killings in Burundi and Congo-Kinshasa. The new dynamics of African civil wars and warlord politics demanded inquiry. Finally, the necessity of international intervention to contain and mediate the violence brought new attention to peacekeeping issues.
COMPARATIVE ETHNIC POLITICS IN THE UNITED STATES: Beyond Black and White
Authors: Segura Gary M. , Rodrigues Helena Alves
Published: February 2006

▪ Abstract  The study of race in American politics has largely been confined to the examination of African-Americans and their relations with whites. Demographic changes in the American population necessitate that we broaden this perspective to include other nonwhite groups. In this essay, we examine the similarities and differences between African-Americans on the one hand and Latinos and Asian-Americans on the other. In particular, we identify factors that are likely to distinguish the political experiences of these groups, focusing particularly on the roles of immigration and group identity. We also examine the state of knowledge regarding circumstances under which intergroup competition and cooperation are likely to occur. We suggest that neither competition nor cooperation is inevitable; rather, the emergence of either will be contingent on the specific historical and demographic circumstances of the community and the choices and attitudes of both political elites and mass publics.
Effect of chloride on pH microclimate and electrogenic Na+absorption across the rumen epithelium of goat and sheep
Authors: Leonhard-Marek S. , Breves G. , Busche R.
Published: February 2006

Active Na+absorption across rumen epithelium comprises Na+/H+exchange and a nonselective cation conductance (NSCC). Luminal chloride is able to stimulate Na+absorption, which has been attributed to an interaction between Cl−/HCO3−and Na+/H+exchangers. However, isolated rumen epithelial cells also express a Cl−conductance. We investigated whether Cl−has an additional effect on electrogenic Na+absorption via NSCC. NSCC was estimated from short-circuit current ( Isc) across epithelia of goat and sheep rumen in Ussing chambers. Epithelial surface pH (pHs) was measured with 5- N-hexadecanoyl-aminofluorescence. Membrane potentials were measured with microelelectrodes. Luminal, but not serosal, Cl−stimulated the Ca2+and Mg2+sensitive Isc. This effect was independent of the replacing anion (gluconate or acetate) and of the presence of bicarbonate. The mean pHsof rumen epithelium amounted to 7.47 ± 0.03 in a low-Cl−solution. It was increased by 0.21 pH units when luminal Cl−was increased from 10 to 68 mM. Increasing mucosal pH from 7.5 to 8.0 also increased the Ca2+and Mg2+sensitive Iscand transepithelial conductance and reduced the fractional resistance of the apical membrane. Luminal Cl−depolarized the apical membrane of rumen epithelium. 5-Nitro-2-(3-phenylpropylamino)-benzoate reduced the divalent cation sensitive Isc, but only in low-Cl−solutions. The results show that luminal Cl−can increase the microclimate pH via apical Cl−/HCO3−or Cl−/OH−exchangers. Electrogenic Na+absorption via NSCC increases with pH, explaining part of the Cl−effects on Na+absorption. The data further show that the Cl−conductance of rumen epithelium must be located at the basolateral membrane.
Downregulation by a long-acting β2-adrenergic receptor agonist and corticosteroid of Staphylococcus aureus-induced airway epithelial inflammatory mediator production
Authors: Fragaki Konstantina , Kileztky Claire , Trentesaux Chantal , Zahm Jean-Marie , Bajolet Odile , Johnson Malcolm , Puchelle Edith
Published: February 2006

Although Staphylococcus aureus is a major cause of pulmonary infection, the role played by this bacterium in the induction of inflammation of human airway epithelial cells (HAEC) is poorly understood. In this study, we investigated the inflammatory response of HAEC to S. aureus soluble virulence factors and demonstrate that the combination of a long-acting β2-adrenergic receptor agonist (salmeterol) with a glucocorticoid (fluticasone propionate) has an anti-inflammatory effect on HAEC. First, we demonstrate increased expression at both the mRNA and protein levels of interleukin (IL)-8, IL-6, and tumor necrosis factor (TNF)-α following incubation of HAEC in the presence of S. aureus soluble virulence factors and the increase of 1) the free nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activities and 2) the phosphorylated (P-) extracellular signal-regulated kinases 1 and 2 (ERK1/ERK2), the P-c-Jun NH2-terminal kinase (JNK), and the P-isoform-α of the NF-κB inhibitor (IκBα). Next, when HAEC were preincubated with the combination of salmeterol and fluticasone propionate, the inflammatory response of HAEC was markedly attenuated in that levels of IL-8, IL-6, TNF-α, NF-κB, AP-1, P-ERK1/ERK2, P-JNK, and P-IκBα decreased significantly. These data emphasize the deleterious effect of S. aureus soluble virulence factors and suggest that the combination of a β2-adrenergic receptor agonist with a glucocorticoid may attenuate the associated airway epithelial inflammation.
Tidal breathing pattern differentially antagonizes bronchoconstriction in C57BL/6J vs. A/J mice
Authors: Chen Bohao , Liu Gustine , Shardonofsky Felix , Dowell Maria , Lakser Oren , Mitchell Richard W. , Fredberg Jeffrey J. , Pinto Lawrence H. , Solway Julian
Published: February 2006

There is abundant evidence that tidal breathing, and especially tidal breathing at elevated minute ventilation, antagonizes the development and persistence of airflow obstruction during bronchoconstrictor stimulation in normal animals and people. Here, we studied the antiobstructive effect of different tidal breathing patterns in C57Bl/6J and A/J mice during bronchoconstriction induced by continuous or bolus infusion of methacholine. Anesthetized, paralyzed mice were mechanically ventilated at 1,500 ml·kg−1·min−1, using each of three breathing patterns: 5 ml/kg, 300 breath/min; 10 ml/kg, 150 breath/min; or 20 ml/kg, 75 breath/min. Changing from 10 ml/kg, 150 breath/min to 20 ml/kg, 75 breath/min, breathing functionally antagonized bronchoconstriction, reducing the level of airflow obstruction induced by methacholine infusion or boluses equivalently in both strains. In marked contrast, changing from 10 ml/kg, 150 breath/min to 5 ml/kg, 300 breath/min, breathing substantially exacerbated methacholine-induced airflow obstruction in A/J mice, whereas it had no significant effect in C57Bl/6J mice. Our results therefore demonstrate that 1) even at moderate, fixed minute ventilation, the precise breathing pattern can influence the degree of airflow obstruction substantially, and 2) the influence of breathing pattern on bronchoconstriction differs considerably between genetically diverse inbred mouse strains. These findings imply that differences in antiobstructive effects of breathing can contribute to differences in apparent airway constrictor responsiveness. Much attention has been placed on dysregulation of contractile function of airway smooth muscle in human disease. We suggest that important pathophysiology might also be found in impairment of the functional antagonist effect of tidal breathing on airflow obstruction.
Relative roles of local and reflex components in cutaneous vasoconstriction during skin cooling in humans
Authors: Alvarez Guy E. , Zhao Kun , Kosiba Wojciech A. , Johnson John M.
Published: February 2006

The reduction in skin blood flow (SkBF) with cold exposure is partly due to the reflex vasoconstrictor response from whole body cooling (WBC) and partly to the direct effects of local cooling (LC). Although these have been examined independently, little is known regarding their roles when acting together, as occurs in environmental cooling. We tested the hypothesis that the vasoconstrictor response to combined LC and WBC would be additive, i.e., would equal the sum of their independent effects. We further hypothesized that LC would attenuate the reflex vasoconstrictor response to WBC. We studied 16 (7 women, 9 men) young (30.5 ± 2 yr) healthy volunteers. LC and WBC were accomplished with metal Peltier cooler-heater probe holders and water-perfused suits, respectively. Forearm SkBF was monitored by laser-Doppler flowmetry (LDF). Cutaneous vascular conductance (CVC) was calculated as LDF/blood pressure. Subjects underwent 15 min of LC alone or 15 min of WBC with and without simultaneous LC, either at equal levels (34–31°C) or as equipotent stimuli (34–28°C LC; 34–31°C WBC). The fall in CVC with combined WBC and LC was greater ( P < 0.05) than for either alone (57.0 ± 5% combined vs. 39.2 ± 6% WBC; 34.4 ± 4% LC) with equipotent cooling, but it was only significantly greater than for LC alone with equal levels of cooling (51.3 ± 8% combined vs. 29.5 ± 4% LC). The sum of the independent effects of WBC and LC was greater than their combined effects (74.9 ± 4 vs. 51.3 ± 8% equal and 73.6 ± 7 vs. 57.0 ± 5% equipotent; P < 0.05). The fall in CVC with WBC at LC sites was reduced compared with control sites (17.6 ± 2 vs. 42.4 ± 8%; P < 0.05). Hence, LC contributes importantly to the reduction in SkBF with body cooling, but also suppresses the reflex response, resulting in a nonadditive effect of these two components.
Direct Demonstration of Instabilities in Oxygen Concentrations within the Extravascular Compartment of an Experimental Tumor
Authors: Lanzen Jennifer , Braun Rod D. , Klitzman Bruce , Brizel David , Secomb Timothy W. , Dewhirst Mark W.
Published: February 2006

To test the hypothesis that temporal variations in microvessel red cell flux cause unstable oxygen levels in tumor interstitium, extravascular oxygenation of R3230Ac mammary tumors grown in skin-fold window chambers was measured using recessed tip polarographic microelectrodes. Red cell fluxes in microvessels surrounding pO2 measurement locations were measured using fluorescently labeled red cells. Temporal pO2 instability was observed in all experiments. Median pO2 was inversely related to radial distance from microvessels. Transient fluctuations above and below 10 mm Hg were consistently seen, except in one experiment near the oxygen diffusion distance limit (140 μm) where pO2 fluctuations were <2 mm Hg and median pO2 was <5 mm Hg. Vascular stasis was not seen in these experiments. These results show that fluctuations in red cell flux, as opposed to vascular stasis, can cause temporal variations in pO2 that extend from perivascular regions to the maximum oxygen diffusion distance. (Cancer Res 2006; 66(4): 2219-23)
Identification of Small Molecules that Sensitize Resistant Tumor Cells to Tumor Necrosis Factor-Family Death Receptors
Authors: Schimmer Aaron D. , Thomas Michael P. , Hurren Rose , Gronda Marcela , Pellecchia Maurizio , Pond Gregory R. , Konopleva Marina , Gurfinkel Debbie , Mawji Imtiaz A. , Brown Ewan , Reed John C.
Published: February 2006

Two major pathways for apoptosis have been identified, involving either mitochondria (intrinsic) or tumor necrosis factor (TNF)-family death receptors (extrinsic) as initiators of caspase protease activation and cell death. Because tumor resistance to TNF-family death receptor ligands is a common problem, helping malignant cells evade host immune defenses, we sought to identify compounds that selectively sensitize resistant tumor cells to death receptor ligands. We screened a 50,000-compound library for agents that enhanced anti-FAS antibody–mediated killing of FAS-resistant PPC-1 prostate cancer cell, then did additional analysis of the resulting hits to arrive at eight compounds that selectively sensitized PPC-1 cells to anti-FAS antibody (extrinsic pathway agonist) without altering sensitivity to staurosporine and etoposide (VP-16; intrinsic pathway agonists). These eight compounds did not increase Fas surface levels and also sensitized PPC-1 cells to apoptosis induced by TNF-family member TNF-related apoptosis-inducing ligand, consistent with a post-receptor mechanism. Of these, two reduced expression of c-FLIP, an intracellular antagonist of the extrinsic pathway. Characterization of the effects of the eight compounds on a panel of 10 solid tumor cell lines revealed two structurally distinct compounds that frequently sensitize to extrinsic pathway agonists. Structure-activity relation studies of one of these compounds revealed a pharmacophore from which it should be possible to generate analogues with improved potency. Altogether, these findings show the feasibility of identifying compounds that selectively enhance apoptosis via the extrinsic pathway, thus providing research tools for uncovering resistance mechanisms and a starting point for novel therapeutics aimed at restoring sensitivity of tumor cells to immune effector mechanisms. (Cancer Res 2006; 66(4): 2367-75)
Targeting of the Receptor Protein Tyrosine Phosphatase β with a Monoclonal Antibody Delays Tumor Growth in a Glioblastoma Model
Authors: Foehr Erik D. , Lorente Gustavo , Kuo Jane , Ram Rosie , Nikolich Karoly , Urfer Roman
Published: February 2006

The receptor protein tyrosine phosphatase β (RPTPβ) is a functional biomarker for several solid tumor types. RPTPβ expression is largely restricted to the central nervous system and overexpressed primarily in astrocytic tumors. RPTPβ is known to facilitate tumor cell adhesion and migration through interactions with extracellular matrix components and the growth factor pleiotrophin. Here, we show that RPTPβ is expressed in a variety of solid tumor types with low expression in normal tissue. To assess RPTPβ as a potential target for treatment of glioblastoma and other cancers, antibodies directed to RPTPβ have been developed and profiled in vitro and in vivo. The recombinant extracellular domain of human short RPTPβ was used to immunize mice and generate monoclonal antibodies that selectively recognize RPTPβ and bind to the antigen with low nanomolar affinities. Moreover, these antibodies recognized the target on living tumor cells as measured by flow cytometry. These antibodies killed glioma cells in vitro when coupled to the cytotoxin saporin either directly or via a secondary antibody. Finally, in vivo studies showed that an anti-RPTPβ immunotoxin (7E4B11-SAP) could significantly delay human U87 glioma tumors in a mouse xenograft model. Unconjugated 7E4B11 provides a modest but statistically significant tumor growth delay when delivered systemically in mice bearing U87 glioma tumors. (Cancer Res 2006; 66(4): 2271-8)
Stalled Replication Induces p53 Accumulation through Distinct Mechanisms from DNA Damage Checkpoint Pathways
Authors: Ho Chui Chui , Siu Wai Yi , Lau Anita , Chan Wan Mui , Arooz Talha , Poon Randy Y.C.
Published: February 2006

Stalled replication forks induce p53, which is required to maintain the replication checkpoint. In contrast to the well-established mechanisms of DNA damage-activated p53, the downstream effectors and upstream regulators of p53 during replication blockade remain to be deciphered. Hydroxyurea triggered accumulation of p53 through an increase in protein stability. The requirement of p53 accumulation for the replication checkpoint was not due to p21CIP1/WAF1 as its down-regulation with short-hairpin RNA did not affect the checkpoint. Similar to DNA damage, stalled replication triggered the activation of the MRN–ataxia telangiectasia mutated (ATM)/ATM and Rad3-related–CHK1/CHK2 axis. Down-regulation of CHK1 or CHK2, however, reduced p53 basal expression but not the hydroxyurea-dependent induction. Moreover, p53 was still stabilized in ataxia telangiectasia cells or in cells treated with caffeine, suggesting that ATM was not a critical determinant. These data also suggest that the functions of ATM, CHK1, and CHK2 in the replication checkpoint were not through the p53-p21CIP1/WAF1 pathway. In contrast, induction of p53 by hydroxyurea was defective in cells lacking NBS1 and BLM. In this connection, the impaired replication checkpoint in several other genetic disorders has little correlation with the ability to stabilize p53. These data highlighted the different mechanisms involved in the stabilization of p53 after DNA damage and stalled replication forks. (Cancer Res 2006; 66(4): 2233-41)
Pten Deficiency Activates Distinct Downstream Signaling Pathways in a Tissue-Specific Manner
Authors: Yoo Lina I. , Liu David W. , Vu Sandrine Le , Bronson Roderick T. , Wu Hong , Yuan Junying
Published: February 2006

PTEN deficiency predisposes to a subset of human cancers, but the mechanism that underlies such selectivity is unknown. We have generated a mouse line that conditionally deletes Pten in urogenital epithelium. These mice develop carcinomas at high frequency in the prostate but at relatively low frequency in the bladder, despite early and complete penetrance of hyperplasia in both organs. Cell proliferation is initially high in the bladder of newborn Pten-deficient mice but within days is inhibited by p21 induction. In contrast, proliferation remains elevated in Pten-deficient prostate, where p21 is never induced, suggesting that p21 induction is a bladder-specific compensatory mechanism to inhibit proliferation caused by Pten deletion. Furthermore, the AKT/mammalian target of rapamycin growth pathway, which is highly activated in Pten-deficient prostate, is not activated in bladder epithelium. Our results reveal alternative downstream signaling pathways activated by Pten deficiency that lead to tissue-specific susceptibilities to tumorigenesis. (Cancer Res 2006; 66(4): 1929-39)
Stimulation of Cyclooxygenase-2 Expression by Bone-Derived Transforming Growth Factor-β Enhances Bone Metastases in Breast Cancer
Authors: Hiraga Toru , Myoui Akira , Choi Mary E. , Yoshikawa Hideki , Yoneda Toshiyuki
Published: February 2006

Cyclooxygenase-2 (COX-2), the rate-limiting enzyme of prostaglandin synthesis, has been implicated in invasiveness and distant metastases of cancer. Bone is one of the most common target sites of cancer metastasis. However, the role of COX-2 in bone metastasis is unclear. We examined the surgical specimens of bone metastases from patients with various types of cancers by using immunohistochemistry and observed evident COX-2 expression in these bone metastases. In a nude mouse model of bone metastasis, the MDA-MB-231 human breast cancer cells showed no COX-2 expression at orthotopic sites, whereas these cells, when metastasized to bone, intensely expressed COX-2, suggesting that the bone microenvironment induced COX-2 expression. Consistent with this notion, inhibition of bone resorption by the bisphosphonate ibandronate reduced COX-2 expression in MDA-MB-231 cells in bone. Transforming growth factor-β (TGFβ), one of the most abundant growth factors stored in bone, increased COX-2 expression and prostaglandin E2 production in MDA-MB-231 cells in culture. MDA-MB-231 cells overexpressing dominant-negative TGFβ type II receptors showed decreased bone metastases and reduced osteoclastic bone resorption with impaired COX-2 expression. The COX-2 inhibitors, NS-398 and nimesulide, significantly suppressed bone metastases with decreased osteoclast number and increased apoptosis in MDA-MB-231 cells. These results suggest that bone-derived TGFβ up-regulates COX-2 expression in breast cancer cells, thereby increasing prostaglandin E2 production, which in turn, stimulates osteoclastic bone destruction, leading to the progression of bone metastases. Our results also suggest that COX-2 is a potential therapeutic target for bone metastases in breast cancer. (Cancer Res 2006; 66(4): 2067-73)
Soluble IGF2 Receptor Rescues Apc
Min/+ Intestinal Adenoma Progression Induced by Igf2 Loss of Imprinting
Authors: Harper James , Burns Jason L. , Foulstone Emily J. , Pignatelli Massimo , Zaina Silvio , Hassan A. Bassim
Published: February 2006

The potent growth-promoting activity of insulin-like growth factor-II (IGF-II) is highly regulated during development but frequently up-regulated in tumors. Increased expression of the normally monoallelic (paternally expressed) mouse (Igf2) and human (IGF2) genes modify progression of intestinal adenoma in the ApcMin/+ mouse and correlate with a high relative risk of human colorectal cancer susceptibility, respectively. We examined the functional consequence of Igf2 allelic dosage (null, monoallelic, and biallelic) on intestinal adenoma development in the ApcMin/+ by breeding with mice with either disruption of Igf2 paternal allele or H19 maternal allele and used these models to evaluate an IGF-II–specific therapeutic intervention. Increased allelic Igf2 expression led to elongation of intestinal crypts, increased adenoma growth independent of systemic growth, and increased adenoma nuclear β-catenin staining. By introducing a transgene expressing a soluble form of the full-length IGF-II/mannose 6-phosphate receptor (sIGF2R) in the intestine, which acts as a specific inhibitor of IGF-II ligand bioavailability (ligand trap), we show rescue of the Igf2-dependent intestinal and adenoma phenotype. This evidence shows the functional potency of allelic dosage of an epigenetically regulated gene in cancer and supports the application of an IGF-II ligand–specific therapeutic intervention in colorectal cancer. (Cancer Res 2006; 66(4): 1940-8)