The assessment of pressure-volume relationship during exercise stress echocardiography predicts left ventricular remodeling and eccentric hypertrophy in patients with chronic heart failure.

BACKGROUND: The contractile response of patients with heart failure (HF) may be assessed by exercise stress echocardiography (ESE)-derived indexes. We sought to test whether ESE parameters are useful to identify the risk of adverse left ventricular (LV) remodeling in patients with chronic HF and reduced or mildly reduced LV ejection fraction (EF). METHODS: We enrolled 155 stabilized patients (age: 62 ± 11 years, 17% female, coronary artery disease 47%) with chronic HF, LV EF ≤50% and LV end-diastolic volume index > 75 ml/m2. All patients underwent a symptom-limited graded bicycle semi-supine ESE, with evaluation of peak stress LV EF, end-systolic pressure-volume relation (ESPVR, i.e. LV elastance) and cardiac power output to LV mass (CPOM). A complete echocardiographic study was performed at baseline and after 6 ± 3 months. Adverse LV remodeling was defined as the association of eccentric LV hypertrophy (LV mass: ≥115 g/m2 for male and ≥ 95 g/m2 for women, and relative wall thickness < 0.32) with an increase in LV end-systolic volume index ≥10% at six months. RESULTS: Adverse LV remodeling was detected in 34 (22%) patients. After adjustment for clinical, biochemical and echocardiographic data, peak ESPVR resulted in the most powerful independent predictor of adverse LV remodeling (OR: 12.5 [95% CI 4.5-33]; p < 0.0001) followed by ischemic aetiology (OR: 2.64 [95% 1.04-6.73]; p = 0.04). CONCLUSION: In patients with HF and reduced or mildly reduced EF, a compromised ESE-derived peak ESPVR, that reflects impaired LV contractility, resulted to be the most powerful predictor of adverse LV remodeling.

Value of combined cardiopulmonary and echocardiography stress test to characterize the haemodynamic and metabolic responses of patients with heart failure and mid-range ejection fraction.

AIMS: To characterize heart failure (HF) with mid-range ejection fraction (HFmrEF), combining cardiopulmonary exercise test, and exercise stress echocardiography. METHODS AND RESULTS: We studied 169 consecutive subjects (age 62.3 ± 11 years; 74% male): 30 healthy controls, 45 patients with HF and preserved EF (HFpEF), 40 HFmrEF, and 54 with HF and reduced EF (HFrEF). Left ventricular (LV) stroke volume (SV), EF, elastance, global longitudinal strain, E/E', oxygen consumption (VO2), and arterial-venous oxygen content difference (AVO2diff) were measured in all exercise stages. HFmrEF revealed baseline features intermediate between HFrEF and HFpEF, except for B-type natriuretic peptide levels, which was similar to HFpEF and significantly lower than HFrEF. Peak VO2 was not significantly different between HF groups. HFrEF exhibited a significantly lower peak SV as compared to either HFpEF or HFmrEF (74.3 ± 21.8 mL vs. 88.0 ± 17.4 mL and 96.5 ± 25.1 mL; P < 0.01), whereas peak heart rate was not significantly different between HF groups. A significantly reduced AVO2diff at peak exercise was apparent in HFpEF and HFmrEF (15.2 ± 3.3 mL/dL and 13.3 ± 4.2 mL/dL) vs. HFrEF (17.±6.6 mL/dL; P < 0.01), whereas no significant difference was reported between HFpEF and HFmrEF. Multivariate analysis in the overall population and all groups revealed peak parameters as independent predictors of peak VO2 (R2 = 0.90, P < 0.0001); AVO2diff showed the largest standardized regression coefficient. CONCLUSION: In HFpEF and HFmrEF, effort intolerance is predominantly due to peripheral factors (AVO2diff), whereas in HFrEF peak VO2 is restricted by low increases in SV. Individual therapy according to which component of VO2 is more impaired is advisable.

Oxygenated amorphous carbon for resistive memory applications.

Carbon-based electronics is a promising alternative to traditional silicon-based electronics as it could enable faster, smaller and cheaper transistors, interconnects and memory devices. However, the development of carbon-based memory devices has been hampered either by the complex fabrication methods of crystalline carbon allotropes or by poor performance. Here we present an oxygenated amorphous carbon (a-COx) produced by physical vapour deposition that has several properties in common with graphite oxide. Moreover, its simple fabrication method ensures excellent reproducibility and tuning of its properties. Memory devices based on a-COx exhibit outstanding non-volatile resistive memory performance, such as switching times on the order of 10 ns and cycling endurance in excess of 10(4) times. A detailed investigation of the pristine, SET and RESET states indicates a switching mechanism based on the electrochemical redox reaction of carbon. These results suggest that a-COx could play a key role in non-volatile memory technology and carbon-based electronics.

Selective actuation of arrays of carbon nanotubes using magnetic resonance.

We introduce the use of ferromagnetic resonance (FMR) to actuate mechanical resonances in as grown arrays of carbon nanotubes (CNTs) loaded with Ni particles (Ni-CNTs). This contactless method is closely related to the magnetic resonance force microscopy technique and provides spatial selectivity of actuation along the array. The Ni-CNT arrays are grown by chemical vapor deposition and are composed of homogeneous CNTs with uniform length (~600 nm) and almost equal diameter (~20 nm), which are loaded with Ni catalyst particles at their tips due to the tip growth mode. The vibrations of the Ni-CNTs are actuated by relying on the driving force that appears due to the FMR excited at about 2 GHz in the Ni particles (diameter ~100 nm). The Ni-CNT oscillations (frequency ~40 MHz) are detected mechanically by atomic force microscopy. The acquired oscillation images of the Ni-CNT uniform array reveal clear maxima in the spatial distribution of the oscillation amplitudes. We attribute these maxima to the "sensitive slices", i.e., the spatial regions of the Ni-CNT array where the FMR condition is met. Similar to magnetic resonance imaging, the sensitive slice is determined by the magnetic field gradient and moves along the Ni-CNT array as the applied magnetic field is ramped. Our excitation method does not require the presence of any additional microfabricated electrodes or coils near the CNTs and is particularly advantageous in cases where the traditional electrical actuation methods are not effective or cannot be implemented. The remote actuation can be effectively implemented also for arrays of other magnetic nanomechanical resonators.

Growth and characterization of horizontally suspended CNTs across TiN electrode gaps.

A technique is proposed to grow horizontal carbon nanotubes (CNTs) bridging metal electrodes and to assess their electrical properties. A test structure was utilized that allows for selective electrochemical sidewall catalyst placement. The selectivity of the technique is based on the connection of the desired metal electrodes to the silicon substrate where the potential for electrochemical deposition was applied. Control over the Ni catalyst size (15-30 nm) and density (up to 3 x 10(11) particles cm(-2)) is demonstrated. Horizontal CNTs with controlled diameter and density were obtained by CVD growth perpendicular to the sidewalls of patterned TiN electrode structures. Electrode gaps with spacings from 200 nm up to 5 microm could be bridged by both direct CNT-electrode contact and CNT-CNT entanglement. The TiN-CNT-TiN and TiN-CNT-CNT-TiN bridges were electrically characterized without any further post-growth contacting. Resistance values as low as 40 Omega were measured for the smallest gap spacing and depended mainly on the number and configuration of the CNT bridges. The proposed method could be implemented for CNT-based horizontal interconnections and be a route to make different nanoelectronic devices such as chemical and electromechanical sensors.

Anti-EphA2 Antibodies with Distinct In Vitro Properties Have Equal In Vivo Efficacy in Pancreatic Cancer.

The EphA2 receptor tyrosine kinase is overexpressed in a variety of human epithelial cancers and is a determinant of malignant cellular behavior in pancreatic adenocarcinoma cells. Moreover, it is expressed in tumor endothelium and its activation promotes angiogenesis. To better clarify the therapeutic potential of monoclonal antibodies (mAbs) directed to the EphA2 receptor, we generated a large number of mAbs by differential screening of phage-Ab libraries by oligonucleotide microarray technology and implemented a strategy for the rapid identification of antibodies with the desired properties. We selected two high-affinity and highly specific EphA2 monoclonal antibodies with different in vitro properties on the human pancreatic tumor cell line MiaPaCa2. One is a potent EphA2-agonistic antibody, IgG25, that promotes receptor endocytosis and subsequent degradation, and the second is a ligand antagonist, IgG28, that blocks the binding to ephrin A1 and is cross-reactive with the mouse EphA2 receptor. We measured the effect of antibody treatment on the growth of MiaPaCa2 cells orthotopically transplanted in nude mice. Both IgG25 and IgG28 had strong antitumor and antimetastatic efficacy. In vivo treatment with IgG25 determined the reduction of the EphA2 protein levels in the tumor and the phosphorylation of FAK on Tyr576 while administration of IgG28 caused a decrease in tumor vascularization as measured by immunohistochemical analysis of CD31 in tumor sections. These data show that in a pancreatic cancer model comparable therapeutic efficacy is obtained either by promoting receptor degradation or by blocking receptor activation.

Differential screening of phage-ab libraries by oligonucleotide microarray technology.

A novel and efficient tagArray technology was developed that allows rapid identification of antibodies which bind to receptors with a specific expression profile, in the absence of biological information. This method is based on the cloning of a specific, short nucleotide sequence (tag) in the phagemid coding for each phage-displayed antibody fragment (phage-Ab) present in a library. In order to set up and validate the method we identified about 10,000 different phage-Abs binding to receptors expressed in their native form on the cell surface (10 k Membranome collection) and tagged each individual phage-Ab. The frequency of each phage-Ab in a given population can at this point be inferred by measuring the frequency of its associated tag sequence through standard DNA hybridization methods. Using tiny amounts of biological samples we identified phage-Abs binding to receptors preferentially expressed on primary tumor cells rather than on cells obtained from matched normal tissues. These antibodies inhibited cell proliferation in vitro and tumor development in vivo, thus representing therapeutic lead candidates.

High-avidity monoclonal antibodies against the human scavenger class B type I receptor efficiently block hepatitis C virus infection in the presence of high-density lipoprotein.

The human scavenger class B type 1 receptor (SR-B1/Cla1) was identified as a putative receptor for hepatitis C virus (HCV) because it binds to soluble recombinant HCV envelope glycoprotein E2 (sE2). High-density lipoprotein (HDL), a natural SR-B1 ligand, was shown to increase the in vitro infectivity of retroviral pseudoparticles bearing HCV envelope glycoproteins and of cell culture-derived HCV (HCVcc), suggesting that SR-B1 promotes viral entry in an HDL-dependent manner. To determine whether SR-B1 participates directly in HCV infection or facilitates HCV entry through lipoprotein uptake, we generated a panel of monoclonal antibodies (MAbs) against native human SR-B1. Two of them, 3D5 and C167, bound to conformation-dependent SR-B1 determinants and inhibited the interaction of sE2 with SR-B1. These antibodies efficiently blocked HCVcc infection of Huh-7.5 hepatoma cells in a dose-dependent manner. To examine the role of HDL in SR-B1-mediated HCVcc infection, we set up conditions for HCVcc production and infection in serum-free medium. HCVcc efficiently infected Huh-7.5 cells in the absence of serum lipoproteins, and addition of HDL led to a twofold increase in infectivity. However, the HDL-induced enhancement of infection had no impact on the neutralization potency of MAb C167, despite its ability to inhibit both HDL binding to cells and SR-B1-mediated lipid transfer. Of note, MAb C167 also potently blocked Huh-7.5 infection by an HCV strain recovered from HCVcc-infected chimpanzees. These results demonstrate that SR-B1 is essential for infection with HCV produced in vitro and in vivo and suggest the possible use of anti-SR-B1 antibodies as therapeutic agents.

Modulation of the immune response induced by gene electrotransfer of a hepatitis C virus DNA vaccine in nonhuman primates.

Induction of multispecific, functional CD4+ and CD8+ T cells is the immunological hallmark of acute self-limiting hepatitis C virus (HCV) infection in humans. In the present study, we showed that gene electrotransfer (GET) of a novel candidate DNA vaccine encoding an optimized version of the nonstructural region of HCV (from NS3 to NS5B) induced substantially more potent, broad, and long-lasting CD4+ and CD8+ cellular immunity than naked DNA injection in mice and in rhesus macaques as measured by a combination of assays, including IFN-gamma ELISPOT, intracellular cytokine staining, and cytotoxic T cell assays. A protocol based on three injections of DNA with GET induced a substantially higher CD4+ T cell response than an adenovirus 6-based viral vector encoding the same Ag. To better evaluate the immunological potency and probability of success of this vaccine, we have immunized two chimpanzees and have compared vaccine-induced cell-mediated immunity to that measured in acute self-limiting infection in humans. GET of the candidate HCV vaccine led to vigorous, multispecific IFN-gamma+CD8+ and CD4+ T lymphocyte responses in chimpanzees, which were comparable to those measured in five individuals that cleared spontaneously HCV infection. These data support the hypothesis that T cell responses elicited by the present strategy could be beneficial in prophylactic vaccine approaches against HCV.

A novel adenovirus type 6 (Ad6)-based hepatitis C virus vector that overcomes preexisting anti-ad5 immunity and induces potent and broad cellular immune responses in rhesus macaques.

Success in resolving hepatitis C virus (HCV) infection has been correlated to vigorous, multispecific, and sustained CD8(+) T-cell response in humans and chimpanzees. The efficacy of inducing T-cell-mediated immunity by recombinant serotype 5 adenovirus vector has been proven in many animal models of infectious diseases, but its immunogenicity can be negatively influenced by preexisting immunity against the vector itself. To evaluate the less prevalent adenovirus serotype 6 (Ad6) as an alternative vector for and HCV vaccine development, we have generated serotype 5 and 6 adenoviral vectors directing expression of the nonstructural region of HCV (MRKAd5-NSmut and MRKAd6-NSmut). Immunogenicity studies in mice showed that the two vectors induced comparable T-cell responses but that only MRKAd6-NSmut was not suppressed in the presence of anti-Ad5 immunity. In contrast, preexisting anti-Ad5 immunity dramatically blunted the immunogenicity of the serotype 5-based HCV vector. Furthermore, MRKAd6-NSmut showed equivalent potency, breadth, and longevity of HCV-specific T-cell responses in rhesus macaques as the corresponding Ad5-based vector over a wide range of doses and was capable of boosting DNA-primed animals even if administered at low doses. These data support the use of the MRKAd6-NSmut for anti-HCV immunotherapy and, more generally, for the Ad6 serotype as a better genetic vaccine vehicle than Ad5.