Is spontaneous echo contrast associated with device-related thrombus or embolic events after left atrial appendage occlusion? - Insights from the multicenter German LAARGE registry.

BACKGROUND: Interventional left atrial appendage occlusion (LAAO) provides an alternative to oral anticoagulation (OAC) for prophylaxis of thromboembolic events (TEs) in nonvalvular atrial fibrillation patients, predominantly in those with high bleeding risk and contraindications for long-term OAC. Although spontaneous echo contrast (SEC) is a well-known risk factor for atrial thrombus formation, little is known about whether this means an increased risk of device-related thrombus (DRT) or TEs following LAAO. METHODS: This substudy of the prospective, multicenter German LAARGE registry assessed two groups according to absence (SEC -) or presence of SEC (SEC +) in preprocedural cardiac imaging. Clinical and echocardiographic parameters were registered up to 1 year after LAAO. RESULTS: Five hundred eighty-eight patients (SEC - 85.5 vs. SEC + 14.5%) were included. More SEC + patients were implanted for OAC non-compliance (11.8 vs. 4.6%, p = 0.008) and a higher proportion received only antiplatelet therapy without OAC at hospital discharge (96.5 vs. 86.0%, p = 0.007). The SEC + patients had larger LA diameters (50 (47; 54) vs. 47 (43; 51) mm, p < 0.001), wider LAA ostia (21 (19; 23) vs. 20 (17; 22) mm at 45°, p = 0.011), and lower left ventricular ejection fraction (50 (45; 60) vs. 60 (50; 60) %, p < 0.001) on admission. Procedural success was very high in both groups (98.1%, p = 1.00). Periprocedural major adverse cardiac and cerebrovascular events and other major complications were rare in both groups (3.8 vs. 4.7%, p = 0.76). At follow-up, DRT was only detected in the SEC - group (3.8 vs. 0%, p = 1.00). The rates of TEs (SEC - 1.2 vs. SEC + 0%, p = 1.00) after hospital discharge and 1-year mortality (SEC - 12.0 vs. SEC + 11.8%, p = 0.96) were not significantly different between the two groups. CONCLUSIONS: Presence of SEC at baseline was not associated with an increased rate of DRT or TEs at 1-year follow-up after LAAO in LAARGE.

CYP3A4 Catalyzes the Rearrangement of the Dual Orexin Receptor Antagonist Daridorexant to 4-Hydroxypiperidinol Metabolites.

The dual orexin receptor antagonist daridorexant was approved in 2022 in the USA and EU for the treatment of insomnia. The purpose of this study was the identification of its metabolic pathways and the human cytochrome P450 (P450) enzymes involved in its biotransformation. With human liver microsomes, daridorexant underwent hydroxylation at the methyl group of the benzimidazole moiety, oxidative O-demethylation of the anisole to the corresponding phenol, and hydroxylation to a 4-hydroxy piperidinol derivative. While the chemical structures of the benzylic alcohol and the phenol proved to be products of standard P450 reactions, 1D and 2D NMR data of the latter hydroxylation product was incompatible with the initially postulated hydroxylation of the pyrrolidine ring and suggested the disappearance of the pyrrolidine ring and formation of a new 6-membered ring. Its formation is best explained by initial hydroxylation of the pyrrolidine ring in 5-position to yield a cyclic hemiaminal. Hydrolytic ring opening then results in an aldehyde that subsequently cyclizes onto one of the benzimidazole nitrogen atoms to yield the final 4-hydroxy piperidinol. The proposed mechanism was substantiated using an N-methylated analogue, which might hydrolyze to the open-chain aldehyde but cannot undergo the final cyclization step. CYP3A4 was the major P450 enzyme responsible for daridorexant metabolism, accounting for 89 % of metabolic turnover.

Association of atrial myopathy in mitral valve disease on safety outcomes in left atrial appendage closure.

BACKGROUND: Patients undergoing left atrial appendage (LAA) occlusion (LAAO) are multi-morbid, including mitral valve disease (MVD) which is associated with anatomic changes of the left atrium (LA). This study aims to identify how atrial myopathy in MVD influences outcomes in LAAO. METHODS: Atrial myopathy in MVD was defined as LA diameter > 45 mm (♀) and > 48 mm (♂) and existing MVD or history of surgical/interventional treatment. Patients were compared with controls from the prospective, multicentre LAArge registry of LAAO. RESULTS: A total of 528 patients (52 MVD, 476 no-MVD) were included. The MVD group was significantly more likely to be older (78.2 years vs 75.9 years, p = 0.036) and female (59.6% vs 37.8%, p = 0.002). Altered LA anatomy was observed in MVD with significantly larger LA diameter (53 mm vs. 48 mm, p < 0.001) and LAA Ostia [at 135° 23.0 mm (20.5, 26.0) vs 20.0 mm (18.0, 23.0), p = 0.002]. Implant success was high with 96.2% and 97.9%, respectively, without differences in severe complications (7.7% vs 4.6%, p = 0.31). One-year mortality (17.8% vs 11.5%, p = 0.19) and a combined outcome of death, stroke, and systemic embolism (20.3% vs 12.4%, p = 0.13) were not different. Independent predictors of the combined outcome were peripheral artery disease (HR 2.41, 95% CI 1.46-3.98, p < 0.001) and chronic kidney disease (HR 3.46, 95% CI 2.02-5.93, p < 0.001) but not MVD and atrial myopathy. CONCLUSION: Patients with MVD present with altered LA anatomy with increased LA and LAA diameter. However, procedural success and safety in LAAO are not compromised. One-year mortality is numerically higher in patients with MVD but driven by comorbidities.

The metal-ionic liquid interface as characterized by impedance spectroscopy and in situ scanning tunneling microscopy.

We summarize our results of electrochemical measurements carried out on inert or close-to-inert metals in ionic liquids, with the aim to explore the metal|ionic liquid interface structure. To this we used electrochemical methods: cyclic voltammetry, impedance spectroscopy, potential of zero total charge measurements and structure-sensitive techniques, such as in situ scanning tunneling spectroscopy. The studied systems were mostly single crystals of noble metals in imidazolium-based ionic liquids. The two main findings are: (i) in the potential window where no Faradaic reactions occur, the interfacial capacitance exhibits a frequency dependence due to double-layer rearrangement processes and (ii) in certain cases ordered anion and cation structures exist at the interface.

Thickness dependence of the triplet spin-valve effect in superconductor-ferromagnet-ferromagnet heterostructures.

BACKGROUND: In nanoscale layered S/F1/N/F2/AF heterostructures, the generation of a long-range, odd-in-frequency spin-projection one triplet component of superconductivity, arising at non-collinear alignment of the magnetizations of F1 and F2, exhausts the singlet state. This yields the possibility of a global minimum of the superconducting transition temperature T c, i.e., a superconducting triplet spin-valve effect, around mutually perpendicular alignment. RESULTS: The superconducting triplet spin valve is realized with S = Nb a singlet superconductor, F1 = Cu41Ni59 and F2 = Co ferromagnetic metals, AF = CoO x an antiferromagnetic oxide, and N = nc-Nb a normal conducting (nc) non-magnetic metal, which serves to decouple F1 and F2. The non-collinear alignment of the magnetizations is obtained by applying an external magnetic field parallel to the layers of the heterostructure and exploiting the intrinsic perpendicular easy-axis of the magnetization of the Cu41Ni59 thin film in conjunction with the exchange bias between CoO x and Co. The magnetic configurations are confirmed by superconducting quantum interference device (SQUID) magnetic moment measurements. The triplet spin-valve effect has been investigated for different layer thicknesses, d F1, of F1 and was found to decay with increasing d F1. The data is described by an empirical model and, moreover, by calculations using the microscopic theory. CONCLUSION: The long-range triplet component of superconducting pairing is generated from the singlet component mainly at the N/F2 interface, where the amplitude of the singlet component is suppressed exponentially with increasing distance d F1. The decay length of the empirical model is found to be comparable to twice the electron mean free path of F1 and, thus, to the decay length of the singlet component in F1. Moreover, the obtained data is in qualitative agreement with the microscopic theory, which, however, predicts a (not investigated) breakdown of the triplet spin-valve effect for d F1 smaller than 0.3 to 0.4 times the magnetic coherence length, ξF1.

Novel S1P1 receptor agonists - Part 4: Alkylaminomethyl substituted aryl head groups.

In a previous communication we reported on the discovery of alkylamino pyridine derivatives (e.g. 1) as a new class of potent, selective and efficacious S1P1 receptor (S1PR1) agonists. However, more detailed profiling revealed that this compound class is phototoxic in vitro. Here we describe a new class of potent S1PR1 agonists wherein the exocyclic nitrogen was moved away from the pyridine ring (e.g. 11c). Further structural modifications led to the identification of novel alkylaminomethyl substituted phenyl and thienyl derivatives as potent S1PR1 agonists. These new alkylaminomethyl aryl compounds showed no phototoxic potential. Based on their in vivo efficacy and ability to penetrate the brain, the 5-alkyl-aminomethyl thiophenes appeared to be the most interesting class. Potent and selective S1PR1 agonist 20e, for instance, maximally reduced the blood lymphocyte count (LC) for 24 h after oral administration of 10 mg/kg to rat and its brain concentrations reached >500 ng/g over 24 h.

Novel S1P(1) receptor agonists--part 3: from thiophenes to pyridines.

In preceding communications we summarized our medicinal chemistry efforts leading to the identification of potent, selective, and orally active S1P1 agonists such as the thiophene derivative 1. As a continuation of these efforts, we replaced the thiophene in 1 by a 2-, 3-, or 4-pyridine and obtained less lipophilic, potent, and selective S1P1 agonists (e.g., 2) efficiently reducing blood lymphocyte count in the rat. Structural features influencing the compounds' receptor affinity profile and pharmacokinetics are discussed. In addition, the ability to penetrate brain tissue has been studied for several compounds. As a typical example for these pyridine based S1P1 agonists, compound 53 showed EC50 values of 0.6 and 352 nM for the S1P1 and S1P3 receptor, respectively, displayed favorable PK properties, and penetrated well into brain tissue. In the rat, compound 53 maximally reduced the blood lymphocyte count for at least 24 h after oral dosing of 3 mg/kg.

Novel S1P(1) receptor agonists--part 2: from bicyclo[3.1.0]hexane-fused thiophenes to isobutyl substituted thiophenes.

Previously, we reported on the discovery of a novel series of bicyclo[3.1.0]hexane fused thiophene derivatives that serve as potent and selective S1P1 receptor agonists. Here, we discuss our efforts to simplify the bicyclohexane fused thiophene head. In a first step the bicyclohexane moiety could be replaced by a simpler, less rigid cyclohexane ring without compromising the S1P receptor affinity profile of these novel compounds. In a second step, the thiophene head was simplified even further by replacing the cyclohexane ring with an isobutyl group attached either to position 4 or position 5 of the thiophene. These structurally much simpler headgroups again furnished potent and selective S1P1 agonists (e.g., 87), which efficiently and dose dependently reduced the number of circulating lymphocytes upon oral administration to male Wistar rats. For several compounds discussed in this report lymphatic transport is an important route of absorption that may offer opportunities for a tissue targeted approach with minimal plasma exposure.

Novel S1P1 receptor agonists--part 1: From pyrazoles to thiophenes.

From a high-throughput screening campaign aiming at the identification of novel S1P1 receptor agonists, the pyrazole derivative 2 emerged as a hit structure. Medicinal chemistry efforts focused not only on improving the potency of the compound but in particular also on resolving its inherent instability issue. This led to the discovery of novel bicyclo[3.1.0]hexane fused thiophene derivatives. Compounds with high affinity and selectivity for S1P1 efficiently reducing the blood lymphocyte count in the rat were identified. For instance, compound 85 showed EC50 values of 7 and 2880 nM on S1P1 and S1P3, respectively, had favorable pharmacokinetic properties in rat and dog, distributed well into brain tissue, and efficiently and dose dependently reduced the blood lymphocyte count in the rat. After oral administration to spontaneously hypertensive rats, the S1P1 selective compound 85 showed no effect on mean arterial blood pressure and affected the heart rate during the wake phase of the animals only.

Electrodynamic coupling of electric dipole emitters to a fluctuating mode density within a nanocavity.

We investigate the impact of rotational diffusion on the electrodynamic coupling of fluorescent dye molecules (oscillating electric dipoles) to a tunable planar metallic nanocavity. Fast rotational diffusion of the molecules leads to a rapidly fluctuating mode density of the electromagnetic field along the molecules' dipole axis, which significantly changes their coupling to the field as compared to the opposite limit of fixed dipole orientation. We derive a theoretical treatment of the problem and present experimental results for rhodamine 6G molecules in cavities filled with low and high viscosity liquids. The derived theory and presented experimental method is a powerful tool for determining absolute quantum yield values of fluorescence.

Image scanning microscopy.

A new microscopy technique is introduced, image scanning microscopy (ISM), which combines conventional confocal-laser scanning microscopy with fast wide-field CCD detection. The technique allows for doubling the lateral optical resolution in fluorescence imaging. The physical principle behind ISM is similar to structured illumination microscopy, by combining the resolving power of confocal-laser scanning microscopy with that of a wide-field imaging microscopy. This Letter describes the theoretical foundation and experimental realization of ISM.

2-imino-thiazolidin-4-one derivatives as potent, orally active S1P1 receptor agonists.

Sphingosine-1-phosphate (S1P) is a widespread lysophospholipid which displays a wealth of biological effects. Extracellular S1P conveys its activity through five specific G-protein coupled receptors numbered S1P(1) through S1P(5). Agonists of the S1P(1) receptor block the egress of T-lymphocytes from thymus and lymphoid organs and hold promise for the oral treatment of autoimmune disorders. Here, we report on the discovery and detailed structure-activity relationships of a novel class of S1P(1) receptor agonists based on the 2-imino-thiazolidin-4-one scaffold. Compound 8bo (ACT-128800) emerged from this series and is a potent, selective, and orally active S1P(1) receptor agonist selected for clinical development. In the rat, maximal reduction of circulating lymphocytes was reached at a dose of 3 mg/kg. The duration of lymphocyte sequestration was dose dependent. At a dose of 100 mg/kg, the effect on lymphocyte counts was fully reversible within less than 36 h. Pharmacokinetic investigation of 8bo in beagle dogs suggests that the compound is suitable for once daily dosing in humans.

Study of layer-by-layer films on thermoresponsive nanogels using temperature-controlled dual-focus fluorescence correlation spectroscopy.

While a few studies have reported on the layer-by-layer (LbL) assembly of polyelectrolytes on soft and porous templates, none have really demonstrated direct proof that the layers are actually on the template. Thermoresponsive nanogels present challenges that render a quantitative proof of successful polyelectrolyte deposition extremely difficult. Additionally, the fate of the polyelectrolyte has never been investigated during the phase transition of the coated nanogel. Here, the auto- and cross-correlation functions of a labeled polyelectrolyte assembled via the LbL technique onto soft and porous thermoresponsive labeled nanogels using dual-focus fluorescence correlation spectroscopy (2f-FCS) are presented. Performing 2f-FCS as a function of temperature, hydrodynamic radii of nanogels coated with various numbers of layers are determined, which are found to be in excellent agreement with values obtained from dynamic light scattering. This study presents irrefutable quantitative evidence of successful LbL assembly on thermoresponsive nanogels and demonstrates that the layers are not stripped off during the phase transition of the nanogels. Forster Resonance Energy Transfer (FRET) detection also supports our findings.

Remote temperature measurements in femto-liter volumes using dual-focus-Fluorescence Correlation Spectroscopy.

Remote temperature measurements in microfluidic devices with micrometer spatial resolution are important for many applications in biology, biochemistry and chemistry. The most popular methods use the temperature-dependent fluorescence lifetime of Rhodamine B, or the temperature-dependent size of thermosensitive materials such as microgel particles. Here, we use the recently developed method of dual-focus fluorescence correlation spectroscopy (2fFCS) for measuring the absolute diffusion coefficient of small fluorescent molecules at nanomolar concentrations and show how these data can be used for remote temperature measurements on a micrometer scale. We perform comparative temperature measurements using all three methods and show that the accuracy of 2fFCS is comparable or even better than that achievable with Rhodamine B fluorescence lifetime measurements. The temperature dependent microgel swelling leads to an enhanced accuracy within a narrow temperature range around the volume phase transition temperature, but requires the availability of specific microgels, whereas 2fFCS is applicable under very general conditions.

The optics and performance of dual-focus fluorescence correlation spectroscopy.

Fluorescence correlation spectroscopy (FCS) is an important spectroscopic technique which can be used for measuring the diffusion and thus size of fluorescing molecules at pico- to nanomolar concentrations. Recently, we introduced an extension of conventional FCS, which is called dual-focus FCS (2fFCS) and allows absolute diffusion measurements with high precision and repeatability. It was shown experimentally that the method is robust against most optical and sample artefacts which are troubling conventional FCS measurements, and is furthermore able to yield absolute values of diffusion coefficients without referencing against known standards. However, a thorough theoretical treatment of the performance of 2fFCS is still missing. The present paper aims at filling this gap. Here, we have systematically studied the performance of 2fFCS with respect to the most important optical and photophysical factors such as cover slide thick-ness, refractive index of the sample, laser beam geometry, and optical satu-ration. We show that 2fFCS has indeed a superior performance when com-pared with conventional FCS, being mostly insensitive to most potential ab-errations when working under optimized conditions.

Calibrating differential interference contrast microscopy with dual-focus fluorescence correlation spectroscopy.

We present a novel calibration technique for determining the shear distance of a Nomarski Differential Interference Contrast prism, which is used in Differential Interference Contrast microscopy as well as for the recently developed dual-focus fluorescence correlation spectroscopy. In both applications, an exact knowledge of the shear distance induced by the Nomarski prism is important for a quantitative data evaluation. In Differential Interference Contrast microscopy, the shear distance determines the spatial resolution of imaging, in dual-focus fluorescence correlation spectroscopy, it represents the extrinsic length scale for determining diffusion coefficients. The presented calibration technique is itself based on a combination of fluorescence correlation spectroscopy and dynamic light scattering. The method is easy to implement and allows for determining the shear distance with nanometer accuracy.

Dual-focus fluorescence correlation spectroscopy of colloidal solutions: influence of particle size.

Fluorescence correlation spectroscopy (FCS) is a powerful technique for measuring diffusion coefficients of small fluorescent molecules at pico- to nanomolar concentrations. Recently, a modified version of FCS, dual-focus FCS (2fFCS), was introduced that significantly improves the reliability and accuracy of FCS measurements and allows for obtaining absolute values of diffusion coefficients without the need of referencing again a known standard. It was shown that 2fFCS gives excellent results for measuring the diffusion of small molecules. However, when measuring colloids or macromolecules, the size of these objects can no longer be neglected with respect to the excitation laser focus. Here, we analyze how 2fFCS data evaluation has to be modified for correctly taking into a count these finite size effects. We exemplify the new method of measuring the absolute size of polymeric particles with simple and complex fluorophore distributions.

Direct evidence of layer-by-layer assembly of polyelectrolyte multilayers on soft and porous temperature-sensitive PNiPAM microgel using fluorescence correlation spectroscopy.

We describe the layer-by-layer assembly of polyelectrolyte multilayers on soft and porous temperature-sensitive poly(N-isopropylacrylamide) (PNiPAM) microgel. Microgels are not hard and rigid but rather are soft and porous particles, and polyelectrolytes not only interdigitate with each other during multilayer formation but also with the microgel. Because of this difference, there could be concerns about the feasibility of the layer-by-layer technique on these systems. The argument is that the layer being deposited is stripping the underlying layer instead of anchoring to the latter, and common methods of characterizing film growth on particles such as zeta-potentials will still show "successful" charge reversal. To address this issue, we used two differently labeled polyelectrolytes during the deposition. Because of the small size of the microgel (400 nm) studied, we cannot distinguish between polyelectrolytes adsorbed on or in the microgel. However, with fluorescence correlation spectroscopy, we can clearly distinguish between free labeled polyelectrolytes and those that are bound to the microgel. Dual-color correlation confirms the presence of both polyelectrolytes bound to the same particle while fluorescence imaging (on a dry sample) provides the visual proof.

Pharmacology of the urotensin-II receptor antagonist palosuran (ACT-058362; 1-[2-(4-benzyl-4-hydroxy-piperidin-1-yl)-ethyl]-3-(2-methyl-quinolin-4-yl)-urea sulfate salt): first demonstration of a pathophysiological role of the urotensin System.

Urotensin-II (U-II) is a cyclic peptide now described as the most potent vasoconstrictor known. U-II binds to a specific G protein-coupled receptor, formerly the orphan receptor GPR14, now renamed urotensin receptor (UT receptor), and present in mammalian species. Palosuran (ACT-058362; 1-[2-(4-benzyl-4-hydroxy-piperidin-1-yl)-ethyl]-3-(2-methyl-quinolin-4-yl)-urea sulfate salt) is a new potent and specific antagonist of the human UT receptor. ACT-058362 antagonizes the specific binding of (125)I-labeled U-II on natural and recombinant cells carrying the human UT receptor with a high affinity in the low nanomolar range and a competitive mode of antagonism, revealed only with prolonged incubation times. ACT-058362 also inhibits U-II-induced calcium mobilization and mitogen-activated protein kinase phosphorylation. The binding inhibitory potency of ACT-058362 is more than 100-fold less on the rat than on the human UT receptor, which is reflected in a pD'(2) value of 5.2 for inhibiting contraction of isolated rat aortic rings induced by U-II. In functional assays of short incubation times, ACT-058362 behaves as an apparent noncompetitive inhibitor. In vivo, intravenous ACT-058362 prevents the no-reflow phenomenon, which follows renal artery clamping in rats, without decreasing blood pressure and prevents the subsequent development of acute renal failure and the histological consequences of ischemia. In conclusion, the in vivo efficacy of the specific UT receptor antagonist ACT-058362 reveals a role of endogenous U-II in renal ischemia. As a selective renal vasodilator, ACT-058362 may be effective in other renal diseases.

[The importance of mammography in the early diagnosis of breast cancer (author's transl)]. / Die Notwendigkeit der Mammographie

Mammography has been performed routinely preoperatively over the last 5 years on 278 patients with breast tumors. In 85 per cent the radiographic findings showed an exact correlation to histologic results. In 12 per cent there was only a partial correlation, in only 3 per cent the mammograpic findings could not be verified by the pathologist. The purpose of this paper is to emphasize that mammography should be considered as the prime diagnostic procedure in the diagnosis of breast disease. The examination of the breast should therefore always be followed by mammography, especially in women at risk and elderly patients. In this connection we would also like to stress the vital cooperation between the radiologist and surgeon both pre- and intraoperatively. and intraoperatively. In summary we would like to emphasize the importance of possibility to achieve a better survial rate in these patients.