Search

β-Adrenoceptor stimulation serves as the most powerful means to increase cardiac output in response to stress or exercise. However, sustained β-adrenoceptor stimulation promotes pathological cardiac remodeling such as myocyte hypertrophy and apoptosis, thus contributing to heart failure. Coexisting cardiac β-adrenoceptor subtypes, mainly β 1 -adrenoceptors and β 2 -adrenoceptors, activate different signaling cascades with β 1 -adrenoceptors coupling to G s and β 2 -adrenoceptors coupling to G s and G i pathways. As a result, sustained β 2 -adrenoceptor stimulation protects cardiomyocytes against apoptosis via a G i –phosphatidylinositol 3-kinase–protein kinase B pathway, whereas chronic β 1 -adrenoceptor stimulation induces myocyte hypertrophy and apoptosis by protein kinase A-independent activation of calmodulin kinase II signaling. These advances in our understanding of β-adrenoceptor subtype signaling identify the mechanisms that underlie the beneficial effects of β-adrenoceptor antagonists and delineate the rationale for combining β 1 -adrenoceptor blockade with β 2 -adrenoceptor activation as a potential therapy for heart failure.

For the inner-city, low SES African-American community sample of this study, prospective data on childhood educational performance and adjustment to school was available for use as control variables in analyses planned for predicting from early adolescent substance use/abuse to work history during adulthood. Results: (1) For the male sub-sample (N = 205), a greater degree of alcohol use up to age 16 was found to predict to poorer work history during the three-year period that preceded age 37. Some possible explanations for these gender-specific findings are discussed.

Three commercially available carbon nanoparticles, i.e., combustion fullerene soot, C60-fullerene, and mixed fullerene, have been characterized using field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM) equipped with energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) as well as surface measurements. Fullerene soot contained a mixture of fullerenic carbons and carbon blacks. Face-centered cubic structure was a predominant phase in the C60-fullerene sample with graphitic and amorphous carbons being minor phases, whereas mixed fullerene was a mixture of fullerene, multiwalled carbon nanotubes, and trace amounts of amorphous carbons.

Multiwalled carbon nanotubes (MWNTs) prepared by carbon arc cathode deposit were characterized by scanning electron microscopy (SEM), high resolution transmission electron microcopy (HRTEM), X-ray diffraction (XRD), and nitrogen gas chromatography BET (Brunauer Emmett Teller) surface measurement. Experimental results indicate that besides carbon nanotubes, the as-received deposit also contains amorphous carbon particles, multi-layer polygonal particles (MPPs), and large graphite platelets. Various tube morphologies are revealed by phase contrast HRTEM images, which are probably associated with different catalyst behaviors involved in the tube growth. Within reasonable fluctuation range, fast Fourier transform (FFT) results and the XRD profile provide essentially identical structural information. The tube-containing deposit exhibits a broad pore size distribution range of 2–100 nm, which is consistent with its isotherm profile.

Background— Myocardial contractile response to β 1 - and β 2 -adrenergic receptor (AR) stimulation is severely impaired in chronic heart failure, in which G i signaling and the ratio of β 2 /β 1 are often increased. Because β 2 -AR but not β 1 -AR couples to G s and G i with the G i coupling negating the G s -mediated contractile response, we determined whether the heart failure–associated augmentation of G i signaling contributes differentially to the defects of these β-AR subtypes and, if so, whether inhibition of G i or selective activation of β 2 -AR/G s by ligands restores β 2 -AR contractile response in the failing heart. Methods and Results— Cardiomyocytes were isolated from 18- to 24-month-old failing spontaneously hypertensive (SHR) or age-matched Wistar-Kyoto (WKY) rat hearts. In SHR cardiomyocytes, either β-AR subtype–mediated inotropic effect was markedly diminished, whereas G i proteins and the β 2 /β 1 ratio were increased. Disruption of G i signaling by pertussis toxin (PTX) enabled β 2 - but not β 1 -AR to induce a full positive inotropic response in SHR myocytes. Furthermore, screening of a panel of β 2 -AR ligands revealed that the contractile response mediated by most β 2 -AR agonists, including zinterol, salbutamol, and procaterol, was potentiated by PTX, indicating concurrent G s and G i activation. In contrast, fenoterol, another β 2 -AR agonist, induced a full positive inotropic effect in SHR myocytes even in the absence of PTX. Conclusions— We conclude that enhanced G i signaling is selectively involved in the dysfunction of β 2 - but not β 1 -AR in failing SHR hearts and that disruption of G i signaling by PTX or selective activation of β 2 -AR/G s signaling by fenoterol restores the blunted β 2 -AR contractile response in the failing heart.

Calmodulin (CaM) as a ubiquitous Ca 2+ sensor interacts with multiple key molecules involved in excitation-contraction (EC) coupling. In the present study, we report that adenoviral expression of a mutant CaM lacking all of its four Ca 2+ -binding sites, CaM(1-4), at a level 6.5-fold over endogenous CaM markedly increases the amplitude and abbreviates the decay time of Ca 2+ transients and contraction in cultured rat ventricular myocytes. To determine the underlying mechanisms, we examined the properties of L-type Ca 2+ channels, Ca 2+ /CaM-dependent protein kinase II (CaMKII), and phospholamban (PLB) in the sarcoplasmic reticulum (SR). We found that CaM(1-4) expression markedly augmented L-type Ca 2+ current amplitude and slowed its inactivation. Surprisingly, overexpression of CaM(1-4) increased CaMKII activity and phosphorylation of PLB-Thr-17. Moreover, CaM(1-4) elevated diastolic Ca 2+ and caffeine-labile Ca 2+ content of the SR. Inhibition of CaMKII by KN-93 or a myristoylated autocamtide-2 related inhibitory peptide prevented the aforementioned PLB phosphorylation and reversed the positive inotropic and relaxant effects, indicating that CaMKII is essential to CaM(1-4) actions. These results demonstrate that CaM modulates Ca 2+ influx, SR Ca 2+ release, and Ca 2+ recycling during cardiac EC coupling. A novel finding of this study is that expression of a Ca 2+ -insensitive CaM mutant can lead to activation of CaMKII in cardiac myocytes.

Background— Enhanced arginine vasopressin levels are associated with increased mortality during end-stage human heart failure, and cardiac arginine vasopressin type 1A receptor (V1AR) expression becomes increased. Additionally, mice with cardiac-restricted V1AR overexpression develop cardiomyopathy and decreased β-adrenergic receptor (βAR) responsiveness. This led us to hypothesize that V1AR signaling regulates βAR responsiveness and in doing so contributes to development of heart failure. Methods and Results— Transaortic constriction resulted in decreased cardiac function and βAR density and increased cardiac V1AR expression, effects reversed by a V1AR-selective antagonist. Molecularly, V1AR stimulation led to decreased βAR ligand affinity, as well as βAR-induced Ca 2+ mobilization and cAMP generation in isolated adult cardiomyocytes, effects recapitulated via ex vivo Langendorff analysis. V1AR-mediated regulation of βAR responsiveness was demonstrated to occur in a previously unrecognized Gq protein–independent/G protein receptor kinase–dependent manner. Conclusions— This newly discovered relationship between cardiac V1AR and βAR may be informative for the treatment of patients with acute decompensated heart failure and elevated arginine vasopressin.

The body is constantly faced with a dynamic requirement for blood flow. The heart is able to respond to these changing needs by adjusting cardiac output based on cues emitted by circulating catecholamine levels. Cardiac β-adrenoceptors transduce the signal produced by catecholamine stimulation via Gs proteins to their downstream effectors to increase heart contractility. During heart failure, cardiac output is insufficient to meet the needs of the body; catecholamine levels are high and β-adrenoceptors become hyperstimulated. The hyperstimulated β1-adrenoceptors induce a cardiotoxic effect, which could be counteracted by the cardioprotective effect of β2-adrenoceptor-mediated Gi signalling. However, β2-adrenoceptor-Gi signalling negates the stimulatory effect of the Gs signalling on cardiomyocyte contraction and further exacerbates cardiodepression. Here, further to the localization of β1- and β2-adrenoceptors and β2-adrenoceptor-mediated β-arrestin signalling in cardiomyocytes, we discuss features of the dysregulation of β-adrenoceptor subtype signalling in the failing heart, and conclude that Gi-biased β2-adrenoceptor signalling is a pathogenic pathway in heart failure that plays a crucial role in cardiac remodelling. In contrast, β2-adrenoceptor-Gs signalling increases cardiomyocyte contractility without causing cardiotoxicity. Finally, we discuss a novel therapeutic approach for heart failure using a Gs-biased β2-adrenoceptor agonist and a β1-adrenoceptor antagonist in combination. This combination treatment normalizes the β-adrenoceptor subtype signalling in the failing heart and produces therapeutic effects that outperform traditional heart failure therapies in animal models. The present review illustrates how the concept of biased signalling can be applied to increase our understanding of the pathophysiology of diseases and in the development of novel therapies.

Although ligand-free, constitutive beta(2)-adrenergic receptor (AR) signaling has been demonstrated in naive cell lines and in transgenic mice overexpressing cardiac beta(2)-AR, it is unclear whether the dominant cardiac beta-AR subtype, beta(1)-AR, shares the ability of spontaneous activation. In the present study, we expressed human beta(1)- or beta(2)-AR via recombinant adenoviral infection in ventricular myocytes isolated from beta(1)beta(2)-AR double knockout mice, creating pure beta(1)-AR and beta(2)-AR systems with variable receptor densities. A contractile response to a nonselective beta-AR agonist, isoproterenol, was absent in double knockout mouse myocytes but was fully restored after adenoviral beta(1)-AR or adenoviral beta(2)-AR infection. Increasing the titer of adenoviral vectors (multiplicity of infection 10-1000) led to a dose-dependent expression of beta(1)- or beta(2)-AR with a maximal density of 1207 +/- 173 (36-fold over the wild-type control value) and 821+/-38 fmol/mg protein (69-fold), respectively. Using confocal immunohistochemistry, we directly visualized the cellular distribution of beta(1)-AR and beta(2)-AR and found that both subtypes were distributed on the cell surface membrane and transverse tubules, resulting in a striated pattern. In the absence of ligand, beta(2)-AR expression resulted in graded increases in baseline cAMP and contractility up to 428% and 233% of control, respectively, at the maximal beta(2)-AR density. These effects were specifically reversed by a beta(2)-AR inverse agonist, ICI 118,551 (10(-7) M). In contrast, overexpression of beta(1)-AR, even at a greater density, failed to enhance either basal cAMP or contractility; the alleged beta(1)-AR inverse agonist, CGP 20712A (10(-6) M), had no significant effect on basal contraction in these cells. Thus, we conclude that acute beta(2)-AR overexpression in cardiac myocytes elicits significant physiological responses due to spontaneous receptor activation; however, this property is beta-AR subtype specific because beta(1)-AR does not exhibit agonist-independent spontaneous activation.

Rapid development of transgenic and gene-targeted mice and acute genetic manipulation via gene transfer vector systems have provided powerful tools for cardiovascular research. To facilitate the phenotyping of genetically engineered murine models at the cellular and subcellular levels and to implement acute gene transfer techniques in single mouse cardiomyocytes, we have modified and improved current enzymatic methods to isolate a high yield of high-quality adult mouse myocytes (5.3 ± 0.5 × 105 cells/left ventricle, 83.8 ± 2.5% rod shaped). We have also developed a technique to culture these isolated myocytes while maintaining their morphological integrity for 2–3 days. The high percentage of viable myocytes after 1 day in culture (72.5 ± 2.3%) permitted both physiological and biochemical characterization. The major functional aspects of these cells, including excitation-contraction coupling and receptor-mediated signaling, remained intact, but the contraction kinetics were significantly slowed. Furthermore, gene delivery via recombinant adenoviral infection was highly efficient and reproducible. In adult β1/β2-adrenergic receptor (AR) double-knockout mouse myocytes, adenovirus-directed expression of either β1- or β2-AR, which occurred in 100% of cells, rescued the functional response to β-AR agonist stimulation. These techniques will permit novel experimental settings for cellular genetic physiology.

Cardiac-specific overexpression of the human beta(2)-adrenergic receptor (AR) in transgenic mice (TG4) enhances basal cardiac function due to ligand-independent spontaneous beta(2)-AR activation. However, agonist-mediated stimulation of either beta(1)-AR or beta(2)-AR fails to further enhance contractility in TG4 ventricular myocytes. Although the lack of beta(2)-AR response has been ascribed to an efficient coupling of the receptor to pertussis toxin-sensitive G(i) proteins in addition to G(s), the contractile response to beta(1)-AR stimulation by norepinephrine and an alpha(1)-adrenergic antagonist prazosin is not restored by pertussis toxin treatment despite a G(i) protein elevation of 1.7-fold in TG4 hearts. Since beta-adrenergic receptor kinase, betaARK1, activity remains unaltered, the unresponsiveness of beta(1)-AR is not caused by betaARK1-mediated receptor desensitization. In contrast, pre-incubation of cells with anti-adrenergic reagents such as muscarinic receptor agonist, carbachol (10(-5)m), or a beta(2)-AR inverse agonist, ICI 118,551 (5 x 10(-7)m), to abolish spontaneous beta(2)-AR signaling, both reduce the base-line cAMP and contractility and, surprisingly, restore the beta(1)-AR contractile response. The "rescued" contractile response is completely reversed by a beta(1)-AR antagonist, CGP 20712A. Furthermore, these results from the transgenic animals are corroborated by in vitro acute gene manipulation in cultured wild type adult mouse ventricular myocytes. Adenovirus-directed overexpression of the human beta(2)-AR results in elevated base-line cAMP and contraction associated with a marked attenuation of beta(1)-AR response; carbachol pretreatment fully revives the diminished beta(1)-AR contractile response. Thus, we conclude that constitutive beta(2)-AR activation induces a heterologous desensitization of beta(1)-ARs independent of betaARK1 and G(i) proteins; suppression of the constitutive beta(2)-AR signaling by either a beta(2)-AR inverse agonist or stimulation of the muscarinic receptor rescues the beta(1)-ARs from desensitization, permitting agonist-induced contractile response.

Coronary atherosclerosis leads to ischaemic heart disease, the single greatest cause of death in developed countries. In the ischaemic heart, blockage of coronary circulation causes myocardial infarction (MI) which produces two types of damage: initial ischaemic injury and reperfusion injury following restoration of blood flow. Ischaemia–reperfusion (IR) injury leads to cardiac contractile dysfunction, loss of cardiomyocytes, maladaptive remodelling, and eventually congestive heart failure. Since mammalian cardiomyocytes are terminally differentiated cells with limited regenerative capacity, preservation of cardiomyocytes is an area that has attracted a lot of interest from both scientists and physicians. In this regard, studies by Kewalraman et al. 1 have defined AMP-activated protein kinase (AMPK) as a powerful cardiac protector against tumour necrosis factor-alpha (TNF-α)-triggered cardiomyocyte apoptosis through phosphorylating Bad and subsequently suppressing mitochondrial apoptotic signalling. This discovery sheds new light on our understanding of the cardiac beneficial effects of clinically used hypoglycaemic drugs such as dexamethasone and metformin (MET), which activate AMPK and are widely used to treat type II diabetes. Equally important, this study may have important clinical relevance, since excessive TNF-α production has been implicated in the pathogenesis of a multitude of metabolic as well as cardiovascular disorders, including obesity, diabetes, and ischaemic heart disease. Thus, we envision that this work would stimulate a flurry of basic and translational studies in the field of cardiovascular biology and medicine and in the area of … *Corresponding author. Tel: +1 410 558 8662; fax: +1 410 558 8150. E-mail address: xiaor{at}grc.nia.nih.gov

We present a new formant-type speech analysis-synthesis-editing system based on the ARX (Auto-Regressive with Exogenous Input) speech production model. One of the key featuresof the proposed system is implementation of the algorithm that automatically estimatesvoicing and unvoiced source parameters as well as formant-antiformant parameters of thesynthesizer directly from a speech utterance. After automatically estimating the parametersfrom the utterance, one can manipulate the estimates using a flexible editing tool that hasbeen developed as a part of the system. Using the parameter values so modified, one cansynthesize speech with various voice qualities. Since the system has been developed on the MS-Windows platform, it is expected to be a useful tool in various areas of speech research.

The subtype of alpha1-adrenoceptor mediating the exogenous noradrenaline-induced vasopressor response in perfused rat hind limb was determined by functional measurements and radioligand binding assays. The potencies (pA2 values) of alpha1A-adrenoceptor-selective antagonists, RS-17053 (N-[2-(2-cyclopropylmethoxy-phenoxy) ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethanamine hydrochloride), WB 4101 (2-(2,6-dimethoxyphenoxyethyl) aminomethyl-1,4 benzodioxane), 5-methyl-urapidil, and the alpha1D-adrenoceptor-selective antagonist, BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspirol[4.5]de cane-7,9-dione), to inhibit the noradrenaline-induced vasopressor response determined by Schild plot were 9.47 +/- 0.21, 9.48 +/- 0.19, 8.10 +/- 0.27 and 6.66 +/- 0.14, respectively, with no slope significantly different from unity. The affinities (K(i) values) of these antagonists were determined by displacement of 125I-BE 2254 (2-beta(4-hydroxyphenyl)-ethylaminomethyl)-tetralone) binding from the cloned alpha1a-, alpha1b-, alpha1d-adrenoceptor, stably expressed in human embryonic kidney (HEK) 293 cells. The pA2 values of the above antagonists correlated well with the binding K(i) values only for alphaIA-adrenoceptors (r = 0.93), but not for alpha1B-adrenoceptors (r = 0.51) and alpha1D-adrenoceptors (r = 0.13). The concentration-vasopressor response curve for noradrenaline was not significantly affected by pretreatment with 50 microM chloroethylclonidine for 30 min. The results suggest that only alpha1A-adrenoceptors mediate the noradrenaline-induced vasopressor response in perfused rat hind limb.

See related article, pages 566–573 Four decades ago, it was thought that the cardiac β-adrenergic receptor (AR) was β1AR, the vascular/bronchial counterpart was β2AR, and that β2AR was either nonexistent or nonfunctional in myocardium.1 In the heart, stimulation of β1AR leads to PKA-dependent phosphorylation of a set of Ca2+ regulatory proteins, including sarcolemmal L-type Ca2+ channels, sarcoplasmic reticulum (SR) Ca2+-release channels (ryanodine receptors), SR Ca2+-ATPase (SERCA) and its regulator phospholamban (PLB), and some myofilament proteins, resulting in positive inotropic, lusitropic, and chronotropic effects. However, over the past decade, compelling evidence has shown that the β2AR subtype is expressed in the heart and its signaling and functionalities markedly differ from those evoked by the closely related βAR subtype, the β1AR. Unlike β1AR, β2AR couples dually to Gs and Gi proteins; the β2AR-Gi signaling pathway plays a crucial role in cardioprotection against apoptotic death of myocytes in culture and in vivo (the “good”), while attenuating the β2AR-Gs-mediated inotropic response (the “bad”) (Figure).2 Now, in the current issue of Circulation Research , He et al revealed one “ugly” facet of the β2AR-Gi signaling in a canine heart failure model.3 They demonstrated that in the failing heart, activation of β2AR dampens the ability of β1AR, the primary cardiac subtype, to stimulate ICa,L, thus resulting in an overall dysfunction of βAR inotropic response in the failing heart (Figure).3 Specifically, the effect of βAR stimulation with a nonselective agonist, isoproterenol (ISO), on ICa,L is strikingly diminished in cardiomyocytes from canine failing heart, but can be revived by disruption …

Protein phosphatase 1 (PP1) and Ca2+/calmodulin-dependent protein kinase δ (CaMKIIδ) are upregulated in heart disorders. Alternative splicing factor (ASF), a major splice factor for CaMKIIδ splicing, can be regulated by both protein kinase and phosphatase. Here we determine the role of PP1 isoforms in ASF-mediated splicing of CaMKIIδ in cells. We found that 1) PP1γ, but not α or β isoform, enhanced the splicing of CaMKIIδ in HEK293T cells; 2) PP1γ promoted the function of ASF, evidenced by the existence of ASF-PP1γ association as well as the PP1γ overexpression- or silencing-mediated change in CaMKIIδ splicing in ASF-transfected HEK293T cells; 3) CaMKIIδ splicing was promoted by overexpression of PP1γ and impaired by application of PP1 inhibitor 1 (I1PP1) or pharmacological inhibitor tautomycetin in primary cardiomyocytes; 4) CaMKIIδ splicing and enhancement of ASF-PP1γ association induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) were potentiated by overexpression of PP1γ and suppressed by inhibition of PP1γ with I1PP1 or tautomycetin in primary cardiomyocytes; 5) functionally, overexpression and inhibition of PP1γ, respectively, potentiated or suppressed the apoptosis and Bax/Bcl-2 ratio, which were associated with the enhanced activity of CaMKII in OGD/R-stimulated cardiomyocytes; and 6) CaMKII was required for the OGD/R induced- and PP1γ exacerbated-apoptosis of cardiomyocytes, evidenced by a specific inhibitor of CaMKII KN93, but not its structural analog KN92, attenuating the apoptosis and Bax/Bcl-2 ratio in OGD/R and PP1γ-treated cells. In conclusion, our results show that PP1γ promotes the alternative splicing of CaMKIIδ through its interacting with ASF, exacerbating OGD/R-triggered apoptosis in primary cardiomyocytes.

Because C50 concrete with antifreeze admixtures has not been used in bridge engineering in cold weather areas, this paper focuses on how to avoid damage from early-age freezing for C50 concrete. First of all, compressive strength and frost resistance test of C50 concrete with antifreeze admixtures were researched in the conditions of -10°C. The concrete mix proportion was optimized, and the critical frozen compressive strength was 15.6MPa, and the critical frozen compressive strength subjected to freezing and thawing was 26MPa. According to the research results of the effect of antifreeze admixtures on concrete durability in the laboratory, the concrete mix proportion for girders of Harbin Yang Ming Beach Bridge in winter construction was determined, and various technical measures were adopted, such as temperature controlling of concrete casting and curing. The field application of C50 concrete for girders at negative temperature was successfully completed.

This paper mainly studies workability and strength development law after curing in standard condition of concrete with LNC-53, which is cast at different negative temperatures (-5°C, -10°C, -15°C, -20°C). The results show that workability of pumped concrete is excellent at the negative temperature, and the slump only reduced 5mm~20mm and the slump flow reduced 10mm~30mm after mixing 1h. By appropriate early curing, the strength of concrete at -7+28d is higher than that at 28d in standard condition. At the temperature of 0~-15°C, the strength of concrete at -90d is 80~100% of that after curing 28d in standard condition, while at the temperature of -15~-20°C, the strength of concrete at -90d could be 70~80% of that after curing 28d in standard condition.

Circulating levels of arginine vasopressin (AVP) are elevated during hypovolemia and during cardiac stress. AVP activates arginine vasopressin type 1A (V(1A))/Gα(q)-coupled receptors in the heart and vasculature and V(2)/Gα(s)-coupled receptors in the kidney. However, little is known regarding the signaling pathways that influence the effects of V(1A) receptor (V(1A)R) activation during cellular injury. Using hypoxia-reoxygenation (H/R) as a cell injury model, we evaluated cell survival and caspase 3/7 activity in H9c2 myoblasts after treatment with AVP. Pretreatment of H9c2 cells with AVP significantly reduced H/R-induced cell death and caspase 3/7 activity, effects that were blocked via both selective V(1A)R inhibition and mitogen-activated protein kinase (MEK1/2) inhibition. AVP increased extracellular-regulated kinase 1/2 (ERK1/2) phosphorylation in a concentration-dependent manner that was sensitive to MEK1/2 inhibition and V(1A)R inhibition, but not V(1B)R or V(2)R inhibition. Discrete elements of the V(1A)/Gα(q)-protein kinase C (PKC) and V(1A)/G protein-coupled receptor kinase (GRK)/β-arrestin signaling cascades were inhibited to dissect the pathways responsible for the protective effects of V(1A)R signaling: Gα(q) (overexpression of Gq-I-ires-green fluorescent protein), PKC (administration of Ro 31-82425; 2-[8-(aminomethyl)-6,7,8,9-tetrahydropyrido[1,2-a]indol-3-yl]-3-(1-methyl-1H-indol-3-yl)maleimide, HCl, bisindolylmaleimide X, HCl), GRK2 [C-terminal GRK2 peptide overexpression and small interfering RNA (siRNA) knockdown], GRK5 (siRNA knockdown), and β-arrestin1 (siRNA knockdown). These studies demonstrated that both Gα(q)/PKC- and GRK2/β-arrestin1-dependent V(1A)R signaling were capable of inducing ERK1/2 phosphorylation in response to AVP stimulation. However, AVP-mediated protection against H/R was elicited only via GRK2- and β-arrestin1-dependent signaling. These results suggest that activation of the V(1A)R in H9c2 cells mediates protective signaling via a GRK2/β-arrestin1/ERK1/2-dependent mechanism that leads to decreased caspase 3/7 activity and enhanced survival under conditions of ischemic stress.

To the Editor: Plasma levels of the neurohormone arginine vasopressin (AVP) are increased in patients with heart failure (HF), and there is a direct relationship between a rise in AVP levels and increased morbidity and mortality [(1)][1]. Arginine vasopressin activates a family of distinct G

Probabilistic linear discriminant analysis (PLDA) is a generative model to explain between and within class variations. When the underlying latent variables are modelled by standard Gaussian distributions, the PLDA recognition scores can be evaluated as a dot product between a high dimensional PLDA feature vector and a weight vector. A key contribution of this paper is showing that the high dimensional PLDA feature vectors can be equivalently (in a non-strict sense) represented as the second-degree polynomial kernel induced features of the vectors formed by concatenating the two input vectors constituting a trial. This equivalence relationship paves the way for the speaker recognition problem to be viewed as a two-class support vector machine (SVM) training problem where higher degree polynomial kernels can give better discriminative power. To alleviate the large scale SVM training problem, we propose a kernel evaluation trick that greatly simplifies the kernel evaluation operations. In our experiments, a combination of multiple second degree polynomial kernel SVMs performed comparably to a state-of-the-art PLDA system. For the analysed test case, SVMs trained with third degree polynomial kernel reduced the EERs on average by 10% relative to that of the SVMs trained with second degree polynomial kernel.

Rationale: Phosphorylation of β 2 -adrenergic receptor (β 2 AR) by a family of serine/threonine kinases known as G protein–coupled receptor kinase (GRK) and protein kinase A (PKA) is a critical determinant of cardiac function. Upregulation of G protein–coupled receptor kinase 2 (GRK2) is a well-established causal factor of heart failure, but the underlying mechanism is poorly understood. Objective: We sought to determine the relative contribution of PKA- and GRK-mediated phosphorylation of β 2 AR to the receptor coupling to G i signaling that attenuates cardiac reserve and contributes to the pathogenesis of heart failure in response to pressure overload. Methods and Results: Overexpression of GRK2 led to a G i -dependent decrease of contractile response to βAR stimulation in cultured mouse cardiomyocytes and in vivo. Importantly, cardiac-specific transgenic overexpression of a mutant β 2 AR lacking PKA phosphorylation sites (PKA-TG) but not the wild-type β 2 AR (WT-TG) or a mutant β 2 AR lacking GRK sites (GRK-TG) led to exaggerated cardiac response to pressure overload, as manifested by markedly exacerbated cardiac maladaptive remodeling and failure and early mortality. Furthermore, inhibition of G i signaling with pertussis toxin restores cardiac function in heart failure associated with increased β 2 AR to G i coupling induced by removing PKA phosphorylation of the receptor and in GRK2 transgenic mice, indicating that enhanced phosphorylation of β 2 AR by GRK and resultant increase in G i -biased β 2 AR signaling play an important role in the development of heart failure. Conclusions: Our data show that enhanced β 2 AR phosphorylation by GRK, in addition to PKA, leads the receptor to G i -biased signaling, which, in turn, contributes to the pathogenesis of heart failure, marking G i -biased β 2 AR signaling as a primary event linking upregulation of GRK to cardiac maladaptive remodeling, failure and cardiodepression.

Cardiac resynchronization therapy (CRT), in which both ventricles are paced to recoordinate contraction in hearts that are dyssynchronous from conduction delay, is the only heart failure (HF) therapy to date to clinically improve acute and chronic function while also lowering mortality. CRT acutely enhances chamber mechanical efficiency but chronically alters myocyte signaling, including improving β-adrenergic receptor reserve. We speculated that the latter would identify unique CRT effects that might themselves be effective for HF more generally. HF was induced in dogs by 6 weeks of atrial rapid pacing with (HFdys, left bundle ablated) or without (HFsyn) dyssynchrony. We used dyssynchronous followed by resynchronized tachypacing (each 3 weeks) for CRT. Both HFdys and HFsyn myocytes had similarly depressed rest and β-adrenergic receptor sarcomere and calcium responses, particularly the β2-adrenergic response, whereas cells subjected to CRT behaved similarly to those from healthy controls. CRT myocytes exhibited suppressed Gαi signaling linked to increased regulator of G protein (heterotrimeric guanine nucleotide–binding protein) signaling (RGS2, RGS3), yielding Gαs-biased β2-adrenergic responses. This included increased adenosine cyclic AMP responsiveness and activation of sarcoplasmic reticulum–localized protein kinase A. Human CRT responders also showed up-regulated myo-cardial RGS2 and RGS3. Inhibition of Gαi (with pertussis toxin, RGS3, or RGS2 transfection), stimulation with a Gαs-biased β2 agonist (fenoterol), or transient (2-week) exposure to dyssynchrony restored β-adrenergic receptor responses in HFsyn to the values obtained after CRT. These results identify a key pathway that is triggered by restoring contractile synchrony and that may represent a new therapeutic approach for a broad population of HF patients.

Carvedilol is one of the most effective beta blockers for preventing ventricular tachyarrhythmias in heart failure, but the mechanisms underlying its favorable antiarrhythmic benefits remain unclear. Spontaneous Ca(2+) waves, also called store overload-induced Ca(2+) release (SOICR), evoke ventricular tachyarrhythmias in individuals with heart failure. Here we show that carvedilol is the only beta blocker tested that effectively suppresses SOICR by directly reducing the open duration of the cardiac ryanodine receptor (RyR2). This unique anti-SOICR activity of carvedilol, combined with its beta-blocking activity, probably contributes to its favorable antiarrhythmic effect. To enable optimal titration of carvedilol's actions as a beta blocker and as a suppressor of SOICR separately, we developed a new SOICR-inhibiting, minimally beta-blocking carvedilol analog, VK-II-86. VK-II-86 prevented stress-induced ventricular tachyarrhythmias in RyR2-mutant mice and did so more effectively when combined with either of the selective beta blockers metoprolol or bisoprolol. Combining SOICR inhibition with optimal beta blockade has the potential to provide antiarrhythmic therapy that can be tailored to individual patients.

This paper presents ongoing research leveraging forensic methods for automatic speaker recognition. Some of the methods forensic scientists employ include identifying speaker distinctive audio segments and comparing these segments using features such as pitch, formant, and other information. Other approaches have also involved performing a phonetic analysis to recognize idiolectal attributes, and an implicit analysis of the demographics of speakers. Inspired by these forensic phonetic approaches, we target three threads of work; hot-spot analysis, speaker style and pronunciation modelling, and demographics analysis. As a result of this work we show that a phonetic analysis conditioned on select speech events (or hot-spots) can outperform a phonetic analysis performed over all speech without conditioning. In the area of pronunciation modelling, one set of results demonstrate significantly improved robustness by exploiting phonetic structure in an automatic speech recognition system. For demographics analysis, we present state-of-the-art results of systems capable of detecting dialect, non-nativeness and native language.

Publisher Summary This chapter discusses the β-adrenergic receptor (βAR) subtype signaling in the heart. The stimulation of βAR, a prototypical member of G protein-coupled receptor (GPCR) superfamily, is broadly involved in metabolic regulation, growth control, muscle contraction, cell survival, and cell death. The major βAR subtypes—β 1 AR and β 2 AR—couple to distinct G proteins and differentially regulate cardiac function and remodeling. Three major discoveries have marked the recent research line with respect to βAR subtype-specific signal transduction. Heart failure (HF) is a complex clinical syndrome featured by extensive abnormalities in the βAR system, including elevated circulating catecholamine levels, selective down regulation and desensitization of β 1 AR, and increased β 2 AR-coupled G i signaling. In particular, the enhanced G i signaling negates β 1 AR- as well as β 2 AR-mediated contractile response, thus contributing to the pathogenesis of HF. Recent translational studies support the concept that inhibition of the G i signaling or selective β 2 AR-G s stimulation with fenoterol markedly improves cardiac remodeling and the function of the failing heart.

Two major β-adrenergic receptor (βAR) subtypes, β(1)AR and β(2)AR, are expressed in mammalian heart with β(1)AR coupling to G(s) and β(2)AR dually coupling to G(s) and G(i) proteins. In many types of chronic heart failure, myocardial contractile response to both β(1)AR and β(2)AR stimulation is severely impaired. The dysfunction of βAR signaling in failing hearts is largely attributable to an increase in G(i) signaling, because disruption of the G(i) signaling restores myocardial contractile response to β(1)AR as well as β(2)AR stimulation. However, the mechanism terminating the β(2)AR-G(i) signaling remains elusive, while it has been shown activation of the G(i) signaling is dependent on agonist stimulation and subsequent PKA-mediated phosphorylation of the receptor. Here we demonstrate that regulator of G protein signaling 2 (RGS2) is a primary terminator of the β(2)AR-G(i) signaling. Specifically, prolonged absence of agonist stimulation for 24h impairs the β(2)AR-G(i) signaling, resulting in enhanced β(2)AR- but not β(1)AR-mediated contractile response in cultured adult mouse cardiomyocytes. Increased β(2)AR contractile response is accompanied by a selective upregulation of RGS2 in the absence of alterations in other major cardiac RGS proteins (RGS3-5) or G(s), G(i) or βAR subtypes. Administration of a βAR agonist, isoproterenol (ISO, 1.0 nM), prevents RGS2 upregulation and restores the β(2)AR-G(i) signaling in cultured cells. Furthermore, RGS2 ablation, similar to βAR agonist stimulation, sustains the β(2)AR-G(i) signaling in cultured cells, whereas adenoviral overexpression of RGS2 suppresses agonist-activated β(2)AR-G(i) signaling in cardiomyocytes and HEK293 cells. These findings not only define RGS2 as a novel negative regulator of the β(2)AR-G(i) signaling but also provide a potential novel target for the treatment of chronic heart failure.

The nicotinic acetylcholine receptor alpha1 (nAChRalpha1) was investigated as a potential fibrogenic molecule in the kidney, given reports that it may be an alternative urokinase (urokinase plasminogen activator; uPA) receptor in addition to the classical receptor uPAR. In a mouse obstructive uropathy model of chronic kidney disease, interstitial fibroblasts were identified as the primary cell type that bears nAChRalpha1 during fibrogenesis. Silencing of the nAChRalpha1 gene led to significantly fewer interstitial alphaSMA(+) myofibroblasts (2.8 times decreased), reduced interstitial cell proliferation (2.6 times decreased), better tubular cell preservation (E-cadherin 14 times increased), and reduced fibrosis severity (24% decrease in total collagen). The myofibroblast-inhibiting effect of nAChRalpha1 silencing in uPA-sufficient mice disappeared in uPA-null mice, suggesting that a uPA-dependent fibroblastic nAChRalpha1 pathway promotes renal fibrosis. To further establish this possible ligand-receptor relationship and to identify downstream signaling pathways, in vitro studies were performed using primary cultures of renal fibroblasts. (35)S-Labeled uPA bound to nAChRalpha1 with a K(d) of 1.6 x 10(-8) m, which was displaced by the specific nAChRalpha1 inhibitor d-tubocurarine in a dose-dependent manner. Pre-exposure of uPA to the fibroblasts inhibited [(3)H]nicotine binding. The uPA binding induced a cellular calcium influx and an inward membrane current that was entirely prevented by d-tubocurarine preincubation or nAChRalpha1 silencing. By mass spectrometry phosphoproteome analyses, uPA stimulation phosphorylated nAChRalpha1 and a complex of signaling proteins, including calcium-binding proteins, cytoskeletal proteins, and a nucleoprotein. This signaling pathway appears to regulate the expression of a group of genes that transform renal fibroblasts into more active myofibroblasts characterized by enhanced proliferation and contractility. This new fibrosis-promoting pathway may also be relevant to disorders that extend beyond chronic kidney disease.

Background Apoptosis is thought to play a role in infarction induced ventricular remodeling. Apoptosis repressor with caspase recruitment domain (ARC) has been shown to limit cardiomyocytes apoptosis; however, its role in the pathogenesis of heart failure is not established. This study examines the regional and temporal relationships of apoptosis, ARC, and remodeling. Methods Myocardium was harvested from the infarct borderzone and remote regions of the left ventricle (LV) at 2 ( n = 8), 8 ( n = 6), and 32 ( n = 5) wk after MI. Activated ARC was compared with myocardial apoptosis in each region at each time. Both were then compared with the progression of remodeling. Results LV systolic volume increased by a factor 1.56 ± 0.06 and 2.09 ± 0.07 at 2 and 8 wk, respectively then stabilized by 32 wk (2.08 ± 0.18). Activated ARC was elevated at 2 wk, diminished at 8 wk, and increased again at 32 wk in both regions. Apoptosis was elevated at 2 wk, and further increased at 8 wk. By 32 wk, apoptosis had diminished significantly. Conclusions In a large animal infarction model, remodeling varied directly with the degree of apoptosis and inversely with ARC activation, suggesting that ARC acts as a natural regulatory phenomenon that limits apoptosis induced ventricular remodeling.

To develop a system for the interactive exploration and examination of histologically derived data that is associated with breast tumors and may be used to evaluate the histologic grade of the tumor.The system integrates pathologist-generated prognostic data with 2-dimensional (2-D) image analysis data, 2-D digital tissue cross-sections and annotations, 3-dimensional (3-D) tumor reconstructions and volumetric analysis, 3D spatial tumor display and recorded prognostic information from available cases in the Drexel University College of Medicine tumor databank. The system consists of 3 components: (1) a user interface for applying 2-D image processing, segmentation and annotation to a digitized histology slide, (2) a distance field interpolation method for contour-based 3D reconstruction of breast tumors and volumetric model analysis routines and (3) a Web-based database management interface for interactive data browsing and searching and multimodality visualization.The system has been implemented and deployed with data from 36 breast cancer cases, 7 of which have been reconstructed in 3-D.Interactive visual analytics technology may be used to create an effective breast tumor evaluation system.

Transmission gratings with a period of 100 nm for extreme ultraviolet interference lithography are fabricated with 2 groups of 50 nm thick Cr bars on a 100 nm thick Si3N4 film. The fabrication process starts with depositing Si3N4 on both sides of (100) Si wafers by LPCVD, followed by electron beam lithography of ZEP520A resist, evaporation of Cr and resist lift-off. A 120 nm thick stop layer of Au is then evaporated onto the surrounding area to eliminate unwanted transmission. Finally, a pair of Si3N4 windows are opened on the back side by dry etching, and the Si under the grating pattern is removed by KOH anisotropic wet etching. Diffraction measurement shows an acceptable first order efficiency of the gratings at the wavelength of 13.4 nm. Using the fabricated gratings at the interference lithography beam line of Shanghai Synchrotron Radiation Facility, economic and efficient fabrication of gratings with a doubled pitch, namely 50 nm period gratings, can be expected.

Understanding the propagation of influence and the concept flow over a network in general has profound theoretical and practical implications. In this paper, we propose a novel approach to ranking individual members of a real-world communication network in terms of their roles in such propagation processes. We first improve the accuracy of the centrality measures by incorporating temporal attributes. Then, we integrate weighted PageRank and centrality scores to further improve the quality of these measures. We valid these ranking measures through a study of an email archive of a W3C working group against an independent list of experts. The results show that time-sensitive Degree, time-sensitive Betweenness and the integration of the weighted PageRank and these centrality measures yield the best ranking results. Our approach partially solves the rank sink problem of PageRank by adjusting flexible jumping probabilities with Betweenness centrality scores. Finally the text analysis based on Latent Semantic Indexing extracts key concepts distributed in different time frames and explores the evolution of the discussion topics in the social network. The overall study depicts an overview of the roles of the actors and conceptual evolution in the social network. These findings are important to understand the dynamics of the social networks.

Spontaneous beating of rabbit sinoatrial node cells (SANCs) is controlled by cAMP-mediated, protein kinase A–dependent local subsarcolemmal ryanodine receptor Ca 2+ releases (LCRs). LCRs activated an inward Na + /Ca 2+ exchange current that increases the terminal diastolic depolarization rate and, therefore, the spontaneous SANC beating rate. Basal cAMP in SANCs is elevated, suggesting that cAMP degradation by phosphodiesterases (PDEs) may be low. Surprisingly, total suppression of PDE activity with a broad-spectrum PDE inhibitor, 3′-isobutylmethylxanthine (IBMX), produced a 9-fold increase in the cAMP level, doubled cAMP-mediated, protein kinase A–dependent phospholamban phosphorylation, and increased SANC firing rate by ≈55%, indicating a high basal activity of PDEs in SANCs. A comparison of specific PDE1 to -5 inhibitors revealed that the specific PDE3 inhibitor, milrinone, accelerated spontaneous firing by ≈47% (effects of others were minor) and increased amplitude of L-type Ca 2+ current ( I Ca,L ) by ≈46%, indicating that PDE3 was the major constitutively active PDE in the basal state. PDE-dependent control of the spontaneous SANC firing was critically dependent on subsarcolemmal LCRs, ie, PDE inhibition increased LCR amplitude and size and decreased LCR period, leading to earlier and augmented LCR Ca 2+ release, Na + /Ca 2+ exchange current, and an increase in the firing rate. When ryanodine receptors were disabled by ryanodine, neither IBMX nor milrinone was able to amplify LCRs, accelerate diastolic depolarization rate, or increase the SANC firing rate, despite preserved PDE inhibition–induced augmentation of I Ca,L amplitude. Thus, basal constitutive PDE activation provides a novel and powerful mechanism to decrease cAMP, limit cAMP-mediated, protein kinase A–dependent increase of diastolic ryanodine receptor Ca 2+ release, and restrict the spontaneous SANC beating rate.

The crucial dependence of normal automaticity of sinoatrial nodal cells (SANC) on CaMKII signaling has previously been linked to an effect to facilitate recovery from inactivation of L-type Ca 2+ channels. More recently, however, it has been discovered that spontaneous, rhythmic, local Ca 2+ releases (LCR’s) from sarcoplasmic reticulum (SR) activate Na + /Ca 2+ exchanger current, imparting an exponential increase to the later part of the spontaneous depolarization that brings the surface membrane to threshold to fire an action potential (AP). Here, in single isolated intact SANC, using the phosphorylation site-specific polyclonal antibody, we show (Fig. A ) that, basal state phospholamban (PLB) phosphorylation at Thr-17, a CaMKII phosphorylation site, is over 3 times greater in SANC than in ventricular cells (VC). The CaMKII inhibitor, KN-93, but not its inactive analog, KN-92, markedly inhibits (by 80%) PLB Thr-17 phosphorylation (Fig. B ). Confocal imaging of saponin permeablized SANC, superfused in physiological solution with 150nM free Ca 2+ and 0.5mM EGTA, showed that KN-93 reduced the LCR frequency by 80% (from 5.6 ± 1.5 to 1.1 ± 0.3/1s × 100 μm) and size by 50% (from 4.0 ± 0.3 to 2.0 ± 0.3 μm). Thus, in addition to an effect on L-type Ca 2+ channels, the high basal CaMKII activation (indexed by PLB phosphorylation at Thr-17) has a major effect to determine the characteristics of spontaneous LCR’s that initiate AP’s and control normal automaticity of SANC.

Identifying the significance of specific concepts in the diffusion of scientific knowledge is a challenging issue concerning many theoretical and practical areas. We introduce an innovative visual analytic approach to integrate microscopic and macroscopic perspectives of a rapidly growing scientific knowledge domain. Specifically, our approach focuses on statistically unexpected phrases extracted from unstructured text of titles and abstracts at the microscopic level in association with the magnitude and timeliness of their citation impact at the macroscopic level. The H-index, originally defined to measure individual scientists. productivity in terms of their citation profiles, is extended in two ways: 1) to papers and terms as a means of dividing these items into two groups so as to replace the less optimal threshold-based divisions, and 2) to take into account the timeliness of the impact of knowledge diffusion in terms of the timing of citations and publications so that attention is particularly drawn towards potentially significant and timely papers. The selected terms are connected to higher-level performance indicators, such as measures derived from the H-index, in the form of decision trees. A top-down traversal of such decision trees provides an intuitive walkthrough of concepts and phrases that may underline potentially significant but currently still latent scientific discoveries. Timeliness measures can also help to identify institutions that are at the forefront of a research field. We illustrate how widely accessible tools such as Google Earth can be utilized to disseminate such insights. The practical significance for digital libraries and fostering scientific discoveries is demonstrated through the astronomical literature related to the Sloan Digital Sky Survey (SDSS).

Stereoisomers of fenoterol and six fenoterol derivatives have been synthesized and their binding affinities for the beta2 adrenergic receptor (Kibeta2-AR), the subtype selectivity relative to the beta1-AR (Kibeta1-AR/Kibeta2-AR) and their functional activities were determined. Of the 26 compounds synthesized in the study, submicromolar binding affinities were observed for (R,R)-fenoterol, the (R,R)-isomer of the p-methoxy, and (R,R)- and (R,S)-isomers of 1-naphthyl derivatives and all of these compounds were active at submicromolar concentrations in cardiomyocyte contractility tests. The Kibeta1-AR/Kibeta2-AR ratios were >40 for (R,R)-fenoterol and the (R,R)-p-methoxy and (R,S)-1-naphthyl derivatives and 14 for the (R,R)-1-napthyl derivative. The binding data was analyzed using comparative molecular field analysis (CoMFA), and the resulting model indicated that the fenoterol derivatives interacted with two separate binding sites and one steric restricted site on the pseudo-receptor and that the chirality of the second stereogenic center affected Kibeta2 and subtype selectivity.

Ca(2+)-calmodulin-dependent protein kinase II (CaMKII) is expressed in many mammalian cells, with the delta isoform predominantly expressed in cardiomyocytes. Previous studies have shown that inhibition of CaMKII protects cardiomyocytes against beta(1)-adrenergic receptor-mediated apoptosis. However, it is unclear whether activation of CaMKII is sufficient to cause cardiomyocyte apoptosis and whether CaMKII signaling is important in heart muscle cell apoptosis mediated by other stimuli. Here, we specifically enhanced or suppressed CaMKII activity using adenoviral gene transfer of constitutively active (CA-CaMKII(deltaC)) or dominant negative (DN-CaMKII(deltaC)) mutants of CaMKII(deltaC) in cultured adult rat cardiomyocytes. Expression of CA-CaMKII(deltaC) promoted cardiomyocyte apoptosis that was associated with increased mitochondrial cytochrome c release and attenuated by co-expression of Bcl-X(L). Importantly, isoform-specific suppression of CaMKII(deltaC) with the DN-CaMKII(deltaC) mutant similar to nonselective CaMKII inhibition by the pharmacological inhibitors (KN-93 or AIP) not only prevented CA-CaMKII(deltaC)-mediated apoptosis but also protected cells from multiple death-inducing stimuli. Thus, activation of CaMKII(deltaC) constitutes a common intermediate by which various death-inducing stimuli trigger cardiomyocyte apoptosis via the primary mitochondrial death pathway.

Understanding the dynamics of knowledge diffusion has profound theoretical and practical implications across a wide variety of domains, ranging from scientific disciplines to education and understanding emergent social phenomena. On the other hand, it involves many challenging issues due to the inherited complexity of knowledge diffusion. In this article, we describe a unifying framework that is designed to facilitate the study of knowledge diffusion through multiple geospatial and semantic perspectives. In particular, we address the role of intrinsic and extrinsic geospatial properties of underlying phenomena in understanding conceptual and geospatial diffusion of knowledge. We illustrate the use of visualizations of geographic distributions of terrorist incidents, the structural evolution of research networks on terrorism and avian flu, and concept-location relations extracted from news stories.

Cepstral mean normalization (CMN) has proved to be a simple noise robust feature processing technique. In its computation, the log-energy feature or C0 is treated in the same way as other cepstral coefficients. Mean normalization is not an effective way to remove effects of additive noise for the log-energy feature. We propose a log-energy dynamic range normalization (ERN) algorithm which normalizes log-energy sequences of an utterance to a target dynamic range. The AURORA 2.0 database together with HTK speech recognition toolkits are used to evaluate the proposed algorithm. The proposed algorithm improves the recognition result by 30.83% over the reference front-end algorithm in clean-condition training. It is superior to the result of CMN, which is 19.30%. It is also confirmed that this technique can be combined with CMN to achieve a 46.33% performance gain. The proposed algorithm is fairly simple and it only requires a very small extra computation load.

In this paper we present the design and evaluation of our biomedical literature searching approaches using the TREC 2004 ad hoc retrieval task in the Genomics track. The main approach taken in our system is to expand queries by exploiting the three widely used strategies - local analysis, global analysis, and ontology-based term re-weighting across various search engines. The experimental results show that (1) ontology-based term re-weighting provides the best results among the three query expansion strategies, (2) expanding the initial query with more precise ontology-based term enhances LSI based local analysis substantially, and (3) including context to term re-weighting and LSI further improves the precision. Experimental results also show that the ontology-based term re-weighting with LUCENE or LEMUR search engines increases the average precision by up to 20.3% or 12.1%, respectively, compared to that of the baseline runs. In addition, the LSI-based local analysis increases the average precision by 9.2% with LEMUR search engine. We believe the approaches of the term re-weighting and LSI-based local analysis may be exploited in other bio-medical domains.

Background: rac-Fenoterol is a β2-adrenoceptor agonist (β2-AR) used in the treatment of asthma. It has two chiral centers and is marketed as a racemic mixture of R,R′- and S,S′-fenoterol (R-F and S-F). Here we report the separation of the R-F and S-F enantiomers and the evaluation of their binding to and activation of the β2-AR. Methods: R-F and S-F were separated from the enantiomeric mixture by chiral chromatography and absolute configuration determined by circular dichroism. β2-AR binding was evaluated using frontal affinity chromatography with a stationary phase containing immobilized membranes from HEK-293 cells that express human β2-AR and standard membrane binding studies using the same membranes. The effect of R-F and S-F on cardiomyocyte contractility was also investigated using freshly isolated adult rat cardiomyocytes. Results: Chiral chromatography of rac-fenoterol yielded separated peaks with an enantioselectivity factor of 1.21. The less retained peak was assigned the absolute configuration of S-F and the more retained peak R-F. Frontal chromatography using membrane-bound β2-AR as the stationary phase and rac-3H-fenoterol as a marker ligand showed that addition of increasing concentrations of R-F to the mobile phase produced concentration-dependent decreases in rac-3H-fenoterol retention, while similar addition of S-F produced no change in rac-3H-fenoterol retention. The calculated dissociation constant of R-F was 472 nM and the number of available binding sites 176 pmol/column, which was consistent with the results from the membrane binding study 460 ± 55 nM (R-F) and 109,000 ± 10,400 nM (S-F). In the cardiomyocytes, R-F increased maximum contractile response from (265 ± 11.6)% to (306 ± 11.8)% of resting cell length (P < 0.05) and reduced EC50 from −7.0 ± 0.270 to −7.1 ± 0.2 log[M] (P < 0.05), while S-F had no significant effect. Discussion: Previous studies have shown that rac-fenoterol acts as an apparent β2-AR/Gs selective agonist and fully restores diminished β2-AR contractile response in cardiomyocytes from failing hearts of spontaneously hypertensive rats (SHR). Here we report the separation of the enantiomers of rac-fenoterol and that R-F is the active component of rac-fenoterol. Further evaluation of R-F will determine if it has enhanced selectivity and specificity for β2-AR/Gs activation and if it can be used in the treatment of congestive heart failure. Chirality, 2006. Published 2006 Wiley-Liss, Inc.

In this paper, we describe the IBM MASTOR systems which handle spontaneous free-form speech-to-speech translation on both laptop and hand-held PDAs. Challenges include speech recognition and machine translation in adverse environments, lack of data and linguistic resources for under-studied languages, and the need to rapidly develop capabilities for new languages. Importantly, the code and models must fit within the limited memory and computational resources of hand-held devices. We describe our approaches, experience, and success in building working free-form S2S systems that can handle two language pairs (including a low-resource language).

Understanding the patterns of sending and receiving email within an organization may help us to understand the historical and social dimensions of that organization. In addition to asynchronous person-to-person communication, email is also used for other purposes such as task management and personal archives. However, tools for visualizing, analyzing, and understanding communication patterns tend to focus on a static view of such patterns. We are developing a visualization system to help users perform tasks from perspectives based on temporal and connectivity patterns. Specifically, our system is designed to support browsing the email archive of W3C working groups. The archive has been made available to the TREC 2005 Enterprise Competition. This system supports both temporal views and linkage views. Temporal views can help users easily find a mail. Linkage views show emails that belong to the same discussion group. Linkage views make it easy to extract related information by showing the relationships of those messages and senders

Search engines have significantly improved the efficiency of bio-medical literature searching. These search engines, however, still return many results that are irrelevant to the intention of a user's query. To improve precision and recall, various query expansion strategies are widely used. In this paper, we explore the three widely used query expansion strategies - local analysis, global analysis, and ontology-based term re- weighting across various search engines. Through experiments, we show that ontology-based term re-weighting works best. Term re-weighting reformulates queries with selection of key original query terms and re-weights these key terms and their associated synonyms from UMLS. The results of experiments show that with LUCENE and LEMUR, the average precision is enhanced by up to 20.3% and 12.1%, respectively, compared to baseline runs. We believe the principles of this term re-weighting strategy may be extended and utilized in other bio-medical domains. users and suggest the user to refine the original query. In this research, three query expansion strategies - local analysis, global analysis, and ontology-based term re-weighting - integrated with the UMLS (Unified Medical Language System) are compared. These methods are applied to the Ad Hoc Retrieval task of the TREC 2004 Genomics task.