Phase diagram of YBa2_2Cu3_3O7−y_{7-y} at T<<Tc_c based on Cu(2) transverse nuclear relaxation

Two maxima in transverse relaxation rate of Cu(2) nuclei in YBa$_2$Cu$_3$O$_{7-y}$ are observed, at T = 35 K and T = 47 K. Comparison of the $^{63}$Cu(2) and $^{65}$Cu(2) rates at T = 47 K indicates the magnetic character of relaxation. The enhancement at T = 47 K of fluctuating local magnetic fields perpendicular to the CuO$_2$ planes is connected with the critical fluctuations of orbital currents. Maximum at T = 35 K is connected with the appearance of inhomogeneous supeconducting phase. Together with data published to date, our experimental results allow to suggest a qualitatively new phase diagram of the superconducting phase.Comment: 4 LaTEX pages + 3 figures in *.ps forma

Water diffusion modulates the cest effect on Tb(III)-mesoporous silica probes

The anchoring of lanthanide(III) chelates on the surface of mesoporous silica nanoparticles (MSNs) allowed their investigation as magnetic resonance imaging (MRI) and chemical exchange saturation transfer (CEST) contrast agents. Since their efficiency is strongly related to the interaction occurring between Ln-chelates and \u201cbulk\u201d water, an estimation of the water diffusion inside MSNs channels is very relevant. Herein, a method based on the exploitation of the CEST properties of TbDO3A-MSNs was applied to evaluate the effect of water diffusion inside MSN channels. Two MSNs, namely MCM-41 and SBA-15, with different pores size distributions were functionalized with TbDO3A-like chelates and polyethylene glycol (PEG) molecules and characterized by HR-TEM microscopy, IR spectroscopy, N2 physisorption, and thermogravimetric analysis (TGA). The different distribution of Tb-complexes in the two systems, mainly on the external surface in case of MCM-41 or inside the internal pores for SBA-15, resulted in variable CEST efficiency. Since water molecules diffuse slowly inside silica channels, the CEST effect of the LnDO3A-SBA-15 system was found to be one order of magnitude lower than in the case of TbDO3A-MCM-41. The latter system reaches an excellent sensitivity of ca. 55 \ub1 5 \ub5M, which is useful for future theranostic or imaging applications

High spin Fe(III)-doped nanostructures as T1 MR imaging probes

Magnetic Resonance Imaging (MRI) T1 contrast agents based on Fe(III) as an alternative to Gd-based compounds have been under intense scrutiny in the last 6-8 years and a number of nanostructures have been designed and proposed for in vivo diagnostic and theranostic applications. Excluding the large family of superparamagnetic iron oxides widely used as T2 -MR imaging agents that will not be covered by this review, a considerable number and type of nanoparticles (NPs) have been employed, ranging from amphiphilic polymer-based NPs, NPs containing polyphenolic binding units such as melanin-like or polycatechols, mixed metals such as Fe/Gd or Fe/Au NPs and perfluorocarbon nanoemulsions. Iron(III) exhibits several favorable magnetic properties, high biocompatibility and improved toxicity profile that place it as the paramagnetic ion of choice for the next generation of nanosized MRI and theranostic contrast agents. An analysis of the examples reported in the last decade will show the opportunities for relaxivity and MR-contrast enhancement optimization that could bring Fe(III)-doped NPs to really compete with Gd(III)-based nanosystems. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease

Surprising Complexity of the [Gd(AAZTA)(H2O)2]- Chelate Revealed by NMR in the Frequency and Time Domains

Typically, Ln(III) complexes are isostructural along the series, which enables studying one particular metal chelate to derive the structural features of the others. This is not the case for [Ln(AAZTA)(H2O)x]- (x = 1, 2) systems, where structural variations along the series cause changes in the hydration number of the different metal complexes, and in particular the loss of one of the two metal-coordinated water molecules between Ho and Er. Herein, we present a 1H field-cycling relaxometry and 17O NMR study that enables accessing the different exchange dynamics processes involving the two water molecules bound to the metal center in the [Gd(AAZTA)(H2O)2]- complex. The resulting picture shows one Gd-bound water molecule with an exchange rate ∼6 times faster than that of the other, due to a longer metal-water distance, in accordance with density functional theory (DFT) calculations. The substitution of the more labile water molecule with a fluoride anion in a diamagnetic-isostructural analogue of the Gd-complex, [Y(AAZTA)(H2O)2]-, allows us to follow the chemical exchange process by high-resolution NMR and to describe its thermodynamic behavior. Taken together, the variety of tools offered by NMR (including high-resolution 1H, 19F NMR as a function of temperature, 1H longitudinal relaxation rates vs B0, and 17O transverse relaxation rates vs T) provides a complete description of the structure and exchange dynamics of these Ln-complexes along the series

Pericardial Thickness Measured With Transesophageal Echocardiography: Feasibility and Potential Clinical Usefulness

AbstractObjectives. This study assessed the reliability of transesophageal echocardiographic measurements of pericardial thickness and the potential diagnostic usefulness of this technique.Background. Transthoracic echocardiography cannot reliably detect thickened pericardium. The superior resolution achieved with transesophageal echocardiography should allow better pericardial definition.Methods. Pericardial thickness measured at 26 locations in 11 patients with constrictive pericarditis who underwent intraoperative transesophageal echocardiography was compared with pericardial thickness measured with electron beam computed tomography. Intraobserver and interobserver variabilities were determined. Pericardial thickness was then measured in 21 normal subjects. With these values as a guide, two observers reviewed 37 transesophageal echocardiographic studies to determine whether echocardiographic measurement of pericardial thickness could be used to distinguish diseased from normal pericardium.Results. The correlation between echocardiographic and computed tomographic measurements (r ≥ 0.95, SE ≤ 0.06 mm, p < 0.0001) was excellent. The ±2 SD limits of agreement were ±1.0 mm or less for pericardial thickness <5.5 mm and ±2.0 mm or less for the entire range of thicknesses. Intraobserver and interobserver agreements were good. Mean normal pericardial thickness was 1.2 ± 0.8 mm (±2 SD) and did not exceed 2.5 mm. Pericardial thickness ≥3 mm on transesophageal echocardiography was 95% sensitive and 86% specific for the detection of thickened pericardium.Conclusions. Measurement of pericardial thickness with transesophageal echocardiography is reproducible and should be a valuable adjunct in assessing constrictive pericarditis.(J Am Coll Cardiol 1997;29:1317–23

Synthesis and preliminary in vitro evaluation of DOTA-Tenatumomab conjugates for theranostic applications in tenascin expressing tumors

Tenatumomab is an anti-tenascin murine monoclonal antibody previously used in clinical trials for delivering radionuclides to tumors by both pre-targeting (biotinylated Tenatumomab within PAGRIT) and direct 131Iodine labeling approaches. Here we present the synthesis and in vitro characterization of three Tenatumomab con-jugates to bifunctional chelating agents (NHS-DOTA, NCS-DOTA and NCS-DTPA). Results indicate ST8198AA1(Tenatumomab-DOTAMA, derived by conjugation of NHS-DOTA), as the most promising candidate in terms ofconjugation rate andyield, stability,antigenimmunoreactivity andaffinity. Labeling efficiency of thedifferentchelators was investigated with a panel of cold metals indicating DOTAMA as the best chelator. Labeling ofTenatumomab-DOTAMA was then optimized with several metals and stability performed confirms suitability of this conjugate for further development. ST8198AA1 represents an improvement of the previous antibody forms because the labeling with radionuclides like177Lu or64Cu would allow theranostic applications in patientsbearing tenascin expressing tumor

Collaborative roles of Temporoparietal Junction and Dorsolateral Prefrontal Cortex in Different Types of Behavioural Flexibility

Behavioural flexibility is essential for everyday life. This involves shifting attention between different perspectives. Previous studies suggest that flexibility is mainly subserved by the dorsolateral prefrontal cortex (DLPFC). However, although rarely emphasized, the temporoparietal junction (TPJ) is frequently recruited during flexible behaviour. A crucial question is whether TPJ plays a role in different types of flexibility, compared to its limited role in perceptual flexibility. We hypothesized that TPJ activity during diverse flexibility tasks plays a common role in stimulus-driven attention-shifting, thereby contributing to different types of flexibility, and thus the collaboration between DLPFC and TPJ might serve as a more appropriate mechanism than DLPFC alone. We used fMRI to measure DLPFC/TPJ activity recruited during moral flexibility, and examined its effect on other domains of flexibility (economic/perceptual). Here, we show the additional, yet crucial role of TPJ: a combined DLPFC/TPJ activity predicted flexibility, regardless of domain. Different types of flexibility might rely on more basic attention-shifting, which highlights the behavioural significance of alternatives.Peer reviewe