Evaluation of chelating agents based on pyridine-azacrown compounds HPATA, PATAM, and HPATPA for Ga and Lu.

In this article, we present the synthesis and characterization of three macrocyclic chelators, HPATA, PATAM, and HPATPA, based on a pyridine-azacrown compound. Their complexation with Ga and Lu has been thoroughly investigated using MALDI TOF MS, H NMR spectroscopy, radiolabeling studies, and experiments in vitro with fetal bovine serum and a 1000-fold molar excess of HEDTA. Our studies have shown that the chelators HPATA and HPATPA form complexes at room temperature with both radionuclides (RCY > 80 % and > 90 % for complexes with HPATA and HPATPA after 30 min, respectively).

Double-Armed 18- and 21-Membered Macrocycles as Potential Chelators for Lead and Bismuth Radiopharmaceuticals.

With increasing clinical applications and interest in targeted alpha therapy, there is growing interest in developing alternative chelating agents for [Pb]Pb and [Bi]Bi that exhibit rapid radiolabeling kinetics and kinetic inertness. Herein we report the synthesis and detailed investigation of diacetate and dipicolinate 18- and 21-membered macrocyclic chelators BADA-18, BADA-21, BADPA-18, and BADPA-21 for the complexation of Pb and Bi ions with potential use in the preparation of radiopharmaceuticals. The formation of mononuclear complexes was established by using ESI-mass spectrometry, and their stability constants were determined by potentiometric titration.

Assessing the biocompatibility and stability of CeO nanoparticle conjugates with azacrowns for use as radiopharmaceuticals.

The application of nanoparticles is promising for the purposes of nuclear medicine due to the possibilities of using them as vectors and transporters of radionuclides. In this study, we have successfully synthesised conjugates of CeO nanoparticles and azacrown ligands. Then, the radiolabelling conditions with radionuclides Zn, Sc and Bi were selected and the kinetic stability of the complexes in biologically significant media was evaluated.

Synthesis of new acyclic chelators H4aPyta and H6aPyha and their complexes with Cu, Ga, Y, and Bi.

In this article, we present the synthesis and characterization of new acyclic pyridine-containing polyaminocarboxylate ligands H4aPyta and H6aPyha, which differ in structural rigidity and the number of chelating groups. Their abilities to form complexes with Cu, Ga, Y, and Bi cations, as well as the stability of the complexes, were evaluated by potentiometric titration method, radiolabeling with the corresponding radionuclides, studies, mass spectrometry, and HPLC. The structures of the resulting complexes were determined using NMR spectroscopy and DFT calculations.

Non-uniform sampling of similar NMR spectra and its application to studies of the interaction between alpha-synuclein and liposomes.

The accelerated acquisition of multidimensional NMR spectra using sparse non-uniform sampling (NUS) has been widely adopted in recent years. The key concept in NUS is that a major part of the data is omitted during measurement, and then reconstructed using, for example, compressed sensing (CS) methods. CS requires spectra to be compressible, that is, they should contain relatively few "significant" points.

Novel candidate theranostic radiopharmaceutical based on strontium hexaferrite nanoparticles conjugated with azacrown ligand.

In this article, we report to the best of our knowledge the first modification of NPs with ligands for combined radiopharmaceuticals. Nanoparticles with suitable magnetic properties can be used both for diagnostics as a contrast for MRI and for therapy, including the insufficiently studied magneto-mechanical therapy. Strontium hexaferrite is one of the few hard-magnetic materials for which stable biocompatible colloidal solutions can be obtained.

CeO-Azacrown Conjugate as a Nanoplatform for Combined Radiopharmaceuticals.

This study is one of the first attempts to assess CeO nanoparticles as a nanoplatform for radiopharmaceuticals with radionuclides. The process of functionalization using a bifunctional azacrown ligand is described, and the resulting conjugates are characterized by IR and Raman spectroscopy. Their complexes with Bi show a high stability in medically relevant media, thus encouraging the further study of these conjugates in vivo as potential combined radiopharmaceuticals.

Accelerating quantitative C NMR spectra using an EXtended ACquisition Time (EXACT) method.

Accurate quantitative C NMR spectra can be accelerated by using EXACT (EXtended ACquisition Time) NMR methods which reduce Nuclear Overhauser Enhancement (NOE) during the FID. This allows 30-50% shorter experiment times to be used when achieving a given level of quantitative accuracy.

Enhanced Nuclear Magnetic Resonance Spectroscopy with Isotropic Mixing as a Pseudodimension.

Chemical analysis based on liquid-state nuclear magnetic resonance spectroscopy exploits numerous observables, mainly chemical shifts, relaxation rates, and internuclear coupling constants. Regarding the latter, the efficiencies of internuclear coherence transfers may be encoded in spectral peak intensities. The dependencies of these intensities on the experimental parameter that influences the transfer, for example, mixing time, are an important source of structural information.

Temperature as an Extra Dimension in Multidimensional Protein NMR Spectroscopy.

NMR spectroscopy is a particularly informative method for studying protein structures and dynamics in solution; however, it is also one of the most time-consuming. Modern approaches to biomolecular NMR spectroscopy are based on lengthy multidimensional experiments, the duration of which grows exponentially with the number of dimensions. The experimental time may even be several days in the case of 3D and 4D spectra.

Non-Stationary Complementary Non-Uniform Sampling (NOSCO NUS) for Fast Acquisition of Serial 2D NMR Titration Data.

NMR spectroscopy offers unique benefits for ligand binding studies on isotopically labelled target proteins. These benefits include atomic resolution, direct distinction of binding sites and modes, a lowest detectable affinity limit, and function independent setup. Yet, retracing protein signal assignments from apo to holo states to derive exact dissociation constants and chemical shift perturbation amplitudes (for ligand docking and structure-based optimization) requires lengthy titration series of 2D heteronuclear correlation spectra at variable ligand concentration that may exceed the protein's lifetime and available spectrometer time.

Accelerated acquisition in pure-shift spectra based on prior knowledge from H NMR.

Pure-shift NMR enhances spectral resolution, but the optimal resolution can only be obtained at the cost of acquisition time. We propose to accelerate pure-shift acquisition using optimised 'burst' non-uniform sampling schemes [I. E.

TReNDS-Software for reaction monitoring with time-resolved non-uniform sampling.

NMR spectroscopy, used routinely for structure elucidation, has also become a widely applied tool for process and reaction monitoring. However, the most informative of NMR methods-correlation experiments-are often useless in this kind of applications. The traditional sampling of a multidimensional FID is usually time-consuming, and thus, the reaction-monitoring toolbox was practically limited to 1D experiments (with rare exceptions, e.

SCoT: Swept coherence transfer for quantitative heteronuclear 2D NMR.

Nuclear magnetic resonance (NMR) spectroscopy is frequently applied in quantitative chemical analysis (qNMR). It is easy to measure one-dimensional (1D) NMR spectra in a quantitative regime (with appropriately long relaxation delays and acquisition times); however, their applicability is limited in the case of complex samples with severe peak overlap. Two-dimensional (2D) NMR solves the overlap problem, but at the cost of biasing peak intensities and hence quantitativeness.

Enabling Fast Pseudo-2D NMR Spectral Acquisition for Broadband Homonuclear Decoupling: The EXACT NMR Approach.

Pseudo-2D NMR spectroscopy provides a means of acquiring broadband homonuclear decoupled spectra useful for structural characterization of complex molecules. However, data points concatenated in the direct dimension in these experiments are acquired over incremented time periods-leading to long acquisition times with no sensitivity benefits due to the absence of signal averaging between scans. Herein, the concept of EXACT NMR spectroscopy ("burst" non-uniform sampling of data points) is explored in pseudo-2D experiments with results revealing little or no loss in spectral quality or signal intensity despite the acceleration of acquisition-up to 400 % in some cases.

Pitfalls in compressed sensing reconstruction and how to avoid them.

Multidimensional NMR can provide unmatched spectral resolution, which is crucial when dealing with samples of biological macromolecules. The resolution, however, comes at the high price of long experimental time. Non-uniform sampling (NUS) of the evolution time domain allows to suppress this limitation by sampling only a small fraction of the data, but requires sophisticated algorithms to reconstruct omitted data points.

Rapid and safe ASAP acquisition with EXACT NMR.

The dangerously high power levels required for fast ASAP-HSQC and ASAP-HMQC experiments are mitigated by employing EXACT NMR. The utility of this technique is demonstrated by application of the EXACT ASAP-HSQC to chemical reaction monitoring, accelerating data acquisition by up to 2 orders of magnitude - providing evidence of it's value in fast quantitative NMR processes.

EXtended ACquisition Time (EXACT) NMR-A Case for 'Burst' Non-Uniform Sampling.

A strong case exists for the introduction of burst non-uniform sampling (NUS) in the direct dimension of NMR spectroscopy experiments. The resulting gaps in the NMR free induction decay can reduce the power demands of long experiments (by switching off broadband decoupling for example) and/or be used to introduce additional pulses (to refocus homonuclear coupling, for example). The final EXtended ACquisition Time (EXACT) spectra are accessed by algorithmic reconstruction of the missing data points and can provide higher resolution in the direct dimension than is achievable with existing non-NUS methods.

Looking at a blinking quantum emitter through time slots: the effect of blind times.

Most experimental observations of physical processes are naturally accompanied by "blind" ("dead") times, which in principle can distort the result of measurements. Here we analyze how the presence of blind times in measurements changes the measured statistics of blinking fluorescence of single quantum dots. We show that information can be extracted even for blinking processes with characteristic times longer than both blind times and time slots between them.

[Urinary excretion of markers for podocyte injury in patients with diabetes mellitus].

Aim: To estimate the urinary excretion of markers for podocyte injury, to specify their value for the early diagnosis of diabetic nephropathy (DN), and to access the risk of its progression in patients with diabetes mellitus (DM) with varying degrees of albuminuria/proteinuria.

Subject And Methods: Seventy-four diabetic patients (30 with type 1 DM and 44 with type 2 DM) were examined and divided into 3 groups according to the urinary concentration in one urinary portion: 1) 41 patients with normal albuminuria (NAU) (<20 mg/l); 2) 13 patients with microalbuminuria (MAU) (20-200 mg/l); 3) 20 patients with proteinuria (PU) (>200 mg/l). A control group included 10 healthy individuals.

[The objective method for recording stapedial reflex during surgery for cochlear implantation].

The purpose of the present study was to develop a method for the objective registration of the stapedial reflex at the contralateral ear during cochlear implantation surgery on the affected one. The excessive pressure in the middle ear (up to 500 daPa) was compensated by the administration of an additional air volume (1 liter) into the AA220 impedance meter pneumatic circuit. A syringe was used to measure variations of pressure in the new pneumatic circuit.

Blinking fluorescence of single donor-acceptor pairs: important role of "dark'' states in resonance energy transfer via singlet levels.

The influence of triplet levels on Förster resonance energy transfer via singlet levels in donor-acceptor (D-A) pairs is studied. Four types of D-A pair are considered: (i) two-level donor and two-level acceptor, (ii) three-level donor and two-level acceptor, (iii) two-level donor and three-level acceptor, and (iv) three-level donor and three-level acceptor. If singlet-triplet transitions in a three-level acceptor molecule are ineffective, the energy transfer efficiency E=I_{A}/(I_{A}+I_{D}), where I_{D} and I_{A} are the average intensities of donor and acceptor fluorescence, can be described by the simple theoretical equation E(F)=FT_{D}/(1+FT_{D}).

[The algorithms for the tuning of the speech processors of cochlear implants].

The tuning of the speech processors of cochlear implants implies the measurement of the threshold perception levels and the achievement of the maximally comfortable level of loudness in each auditory channel. The authors present a detailed description of the approach to the optimal tuning including the sequence of procedures and manipulations for this purpose, from the first tuning to the achievement of the desired result. This algorithm summarizes the worldwide and the authors' own experience based on the original investigations that have been carried in the Sankt-Peterburg Research Institute of Otorhinolaryngology and Speech during more than 15 years.

[Monitoring of implant electrode impedance].

Monitoring of implant reference and active electrode impedance was carried out intraoperatively, at the first fitting, during the first two weeks after the first fitting, and within the next 6 months. It was shown that impedance of the electrodes during surgery was significantly lower than after the first fitting. Moreover, the intraoperative impedance of all active electrodes was significantly lower than in the postoperative period.