Local circuit amplification of spatial selectivity in the hippocampus.

Local circuit architecture facilitates the emergence of feature selectivity in the cerebral cortex1. In the hippocampus, it remains unknown whether local computations supported by specific connectivity motifs2 regulate the spatial receptive fields of pyramidal cells3. Here we developed an in vivo electroporation method for monosynaptic retrograde tracing4 and optogenetics manipulation at single-cell resolution to interrogate the dynamic interaction of place cells with their microcircuitry during navigation. We found a local circuit mechanism in CA1 whereby the spatial tuning of an individual place cell can propagate to a functionally recurrent subnetwork5 to which it belongs. The emergence of place fields in individual neurons led to the development of inverse selectivity in a subset of their presynaptic interneurons, and recruited functionally coupled place cells at that location. Thus, the spatial selectivity of single CA1 neurons is amplified through local circuit plasticity to enable effective multi-neuronal representations that can flexibly scale environmental features locally without degrading the feedforward input structure.

Immediate major dynamic changes in the T- and NK-cell subset composition after cardiac transplantation.

Early kinetics of lymphocyte subsets involved in tolerance and rejection following heart transplantation (HTx) are barely defined. Here, we aimed to delineate the early alloimmune response immediately after HTx. Therefore, blood samples from 23 heart-transplanted patients were collected before (pre-), immediately (T0), 24 hours (T24), and 3 weeks (3 wks) after HTx. Immunophenotyping was performed using flow cytometry. A significant increase was detected for terminally differentiated (TEMRA) CD4+ or CD8+ T cells and CD56dim CD16+ NK cells immediately after HTx linked to a decrease in naïve CD8+ and CM CD4+ T as well as CD56bright CD16- NK cells, returning to baseline levels at T24. More detailed analyses revealed increased CD69+ CD25- and diminished CD69- CD25- CD4+ or CD8+ T-cell proportions at T0 associated with decreasing S1PR1 expression. Passenger T and NK cells were found at low frequencies only in several patients at T0 and did not correlate with lymphocyte alterations. Collectively, these results suggest an immediate, transient shift toward memory T and NK cells following HTx. Opposite migratory properties of naïve versus memory T and NK cells occurring in the early phase after HTx could underlie these observations and may impinge on the development of allo-specific immune responses.

A Volume-Adjustable Artificial Womb for Extremely Preterm Infants.

More than 13 million children are born preterm annually. Prematurity-related mortality accounts for 0.9 million deaths worldwide. The majority of those affected are Extremely Preterm Infants (gestational age less than 28 weeks). Immaturity causes organ failure and specific morbidities like germinal matrix hemorrhage, bronchopulmonary dysplasia, and necrotizing enterocolitis. Artificial womb and placenta technologies address these issues. As a bridge-to-life technology, they provide a liquid environment to allow organ maturation under more physiological conditions. The proposed artificial womb can adapt to fetal growth. Volume adjustment is achieved by removing fluid from the interspace between an inner and outer chamber. Results of the in vitro tests showed a temperature constancy of 36.8°C ± 0.3°C without pressure loss over 7 days. The volume of the inner sac was variable between 3.6 and 7.0 L. We designed a filtration and disinfection system for this particular purpose. This system has proven strong disinfection capabilities, effective filtering of metabolic waste, and the ability to avoid phospholipid washout. The presented artificial womb has sufficient volume variability to adapt to the physiologic growth of an extremely preterm neonate over a 4-week period. We regard this as an important step in the development of this bridge-to-life technology.

The LDL receptor is regulated by membrane cholesterol as revealed by fluorescence fluctuation analysis.

Membrane cholesterol-rich domains have been shown to be important for regulating a range of membrane protein activities. Low-density lipoprotein receptor (LDLR)-mediated internalization of cholesterol-rich LDL particles is tightly regulated by feedback mechanisms involving intracellular sterol sensors. Since LDLR plays a role in maintaining cellular cholesterol homeostasis, we explore the role that membrane domains may have in regulating LDLR activity. We expressed a fluorescent LDLR-mEGFP construct in HEK293T cells and imaged the unligated receptor or bound to an LDL/DiI fluorescent ligand using total internal reflection fluorescence microscopy. We studied the receptor's spatiotemporal dynamics using fluorescence fluctuation analysis methods. Image cross correlation spectroscopy reveals a lower LDL-to-LDLR binding fraction when membrane cholesterol concentrations are augmented using cholesterol esterase, and a higher binding fraction when the cells are treated with methyl-ß-cyclodextrin) to lower membrane cholesterol. This suggests that LDLR's ability to metabolize LDL particles is negatively correlated to membrane cholesterol concentrations. We then tested if a change in activity is accompanied by a change in membrane localization. Image mean-square displacement analysis reveals that unligated LDLR-mEGFP and ligated LDLR-mEGFP/LDL-DiI constructs are transiently confined on the cell membrane, and the size of their confinement domains increases with augmented cholesterol concentrations. Receptor diffusion within the domains and their domain-escape probabilities decrease upon treatment with methyl-ß-cyclodextrin, consistent with a change in receptor populations to more confined domains, likely clathrin-coated pits. We propose a feedback model to account for regulation of LDLR within the cell membrane: when membrane cholesterol concentrations are high, LDLR is sequestered in cholesterol-rich domains. These LDLR populations are attenuated in their efficacy to bind and internalize LDL. However, when membrane cholesterol levels drop, LDL has a higher binding affinity to its receptor and the LDLR transits to nascent clathrin-coated domains, where it diffuses at a slower rate while awaiting internalization.

Electronic spectroscopy of homo- and heterometallic binuclear coinage metal phosphine complexes in isolation.

Binuclear coinage metal phosphine complexes are examined under ion trap isolation in order to elucidate their noncovalent binding, structural properties and intrinsic electronic spectra. Our survey shows an intriguing order of electronic transitions obtained by in situ synthesis and mass-spectrometrically supported UV photodissociation spectroscopy on a series of six isolated homo- and heterobinuclear complexes of type [MM'(dcpm)2]2+ (M, M' = CuI, AgI, AuI; dcpm = bis(dicyclohexyl-phosphino)methane). This approach provides the unique opportunity to study all possible coinage metal interactions within a fixed ligand framework. A successive blue-shift (33 700-38 500 cm-1; 297-260 nm) of the lowest-energy bright electronic transition energy in gas phase was observed in the order of Cu2 < CuAu < CuAg < Au2 < AgAu < Ag2. This order was reproduced by quantum chemical calculations using a scalar-relativistic GW-Bethe-Salpeter-equation (GW-BSE) approach. Theory ascribes the electronic bands of all complexes to metal-centered 1MC(dσ*-pσ) transitions revealing a strengthening of metal-metal' (M-M') binding upon excitation, in agreement to mass spetrometric results. A test of the correlation of transition energies with M-M' distance by quantum chemical calculations of single point energies as a function of intermetallic distance indicates qualitative agreement with experimental results. However, the experimentally observed high sensitivity of spectroscopic shifts towards metal composition cannot be accounted for solely by M-M' distance variation. The differences in electronic transitions are qualitatively rationalized by the varying (n + 1)s (n = 3, 4, 5) orbital contributions (increase from Cu2via CuAu/CuAg to Au2/AgAu/Ag2) within the nd(n + 1)s/p-hybridization for the ground electronic state of the different complexes, whereas the excited state (of (n + 1)p orbital character) shows significantly less variation in energy. In particular, the observed spectroscopic and mass spectrometric sequence for the Ag/Au complexes is traced back to the interplay of Pauli repulsion and variation in metal-ligand bond strength within the orbital hybridization model.

Detection of physiological control inputs preload and afterload from intrinsic pump parameters in total artificial heart.

BACKGROUND: In the total artificial heart (TAH), the inputs to the physiological control unit, preload, and afterload, are detected from intrinsic pump parameters (e.g., motor current). Within this study, their detection techniques are developed, and their reliability in pre- and afterload prediction is mapped for a broad range of cardiovascular system states. METHODS: We used ReinHeart TAH which is a fully implantable TAH with a plunger coil drive that is alternately emptying the left and right chambers. From the coil currents we first derived a force generated by the piston with respect to its position and then analyzed its pattern to detect (1) preload-chamber filling, found as piston position at begin ejection and (2) afterload-mean outflow pressures, determined as linearly calibrated average piston force during ejection. TAH is then integrated into a mock loop circulation (MLC) which is set to 135 different steady operating points varying in chamber filling (0%-100%, five steps), mean outflow pressures (system circulation: 60-90-120 mm Hg, pulmonary circulation: 15-30-45 mm Hg), and heart cycle duration (171-600 ms in seven non-equidistant steps). The detected preload and afterload are compared to MLC set values, and the errors are mapped. RESULTS: Respectively for the left and right chambers, the preload was detectable in 134 and 118 operating points and the mean error was ±3% and ±2%. The afterload was detectable in 135 and 87 operating points and the mean error was 37% and 30% respectively for left and right circulation. The operational points that are further away from homeostatic equilibrium values generally yielded larger errors. The largest errors were observed for right circulation at long cycle duration, low afterload, and low filling. CONCLUSIONS: The study yields reliable preload estimation in a broad range of physiological states, particularly for left circulation. Detection of afterload needs further improvements. The study revealed a need for piston movement optimization within the ReinHeart TAH during the early phase of systole.

Satellite images as tools of visual diplomacy: NASA's ozone hole visualizations and the Montreal Protocol negotiations.

On 16 September 1987, the main chlorofluorocarbon-producing and -consuming countries signed the Montreal Protocol, despite the absence of a scientific consensus on the mechanisms of ozone depletion over Antarctica. We argue in this article that the rapid diffusion from late 1985 onwards of satellite images showing the Antarctic ozone hole played a significant role in this diplomatic outcome. Whereas negotiators claimed that they chose to deliberately ignore the Antarctic ozone hole during the negotiations since no theory was able yet to explain it, the images still loomed large for many of the actors involved. In Western countries, the National Aeronautics and Space Administration's (NASA) satellite visualizations were diffused through the general press and television stations. Other popular and mass media outlets followed quickly. In describing the circulation and appropriation processes of these images within and beyond the scientific and negotiation arenas, we show that the ozone hole images did play an important part in ozone diplomacy in the two years leading up to the signing of the Montreal Protocol, both in the expert and diplomatic arenas and as public diplomacy tools. We conclude by encouraging scholars to engage with new visual archives and to contribute to the development of the vibrant new field of research on visual diplomacy.

Heart transplantation across preformed donor-specific antibody barriers using a perioperative desensitization protocol.

Heart transplantation across preformed donor-specific HLA-antibody barriers is associated with impaired short- and long-term survival. Therefore, in recipients with preformed anti-HLA antibodies, waiting for crossmatch-negative donors is standard practice. As an alternative strategy, recipients with preformed anti-HLA donor specific antibodies have been managed at our institutions with a perioperative desensitization regimen. A retrospective analysis was performed comparing heart transplant recipients with preformed donor-specific HLA-antibodies to recipients without donor-specific antibodies. Recipients with a positive virtual crossmatch received a perioperative desensitization protocol including tocilizumab intraoperatively, plasma exchange and rituximab followed by a six-month course of IgGAM. Among the 117 heart-transplanted patients, 19 (16%) patients underwent perioperative desensitization, and the remaining 98 (84%) patients did not. Cold ischemic time, posttransplant extracorporeal life support for primary graft dysfunction, and intensive care unit stay time did not differ between groups. At 1-year follow-up, freedom from pulsed steroid therapy for presumed rejection and biopsy-confirmed acute cellular or humoral rejection did not differ between groups. One-year survival amounted to 94.7% in the treated patients and 81.4% in the control group. Therefore, heart transplantation in sensitized recipients undergoing a perioperative desensitization appears safe with comparable postoperative outcomes as patients with a negative crossmatch.

Identification of distinct secretory patterns and their regulatory networks of ischemia versus reperfusion phases in clinical heart transplantation.

BACKGROUND: Ischemia/reperfusion injury (IRI) is associated with inflammatory responses contributing to the development of primary graft dysfunction (PGD) and rejection. Here, we investigated the pathophysiology of IRI and the early phase after heart transplantation (HTx) regarding its cytokine/chemokine and endothelial networks. METHODS: Using multiplex technology, we assessed protein concentrations in plasma samples of HTx recipients (n = 11) pre-, postoperatively, 24 h and 3 weeks after HTx. The same proteins were quantified in organ storage solutions at the end of heart storage (n = 10). Unsupervised cluster, principal component analysis (PCA), K-nearest neighbor (KNN) network classifier analysis, ANOVA and Spearman correlation analyses were performed to identify specific patterns for IRI and individual kinetics of important soluble factors in HTx. RESULTS: Unique patterns of soluble factors were identified in plasma of HTx patients. KNN analysis defined IL-10, IL-6, sIL-6Rα, IL-1RA, IL-16, sVEGFR-1, IGFBP-1, HGF and sHer-2 as strongest signals directly post-Tx declining 24 hrs after HTx. By contrast, MIF, osteopontin (OPN), sVCAM-1 and sICAM-1, IGFBP-1, SCGF-ß, HGF were highly enriched in organ storage solutions, reflecting distinct ischemic (storage solution) vs. reperfusion (plasma) signatures. CONCLUSIONS: We identified specific inflammatory signatures for ischemic vs. reperfusion phases of HTx, associated with pro- as well as anti-inflammatory and endothelial biomarker candidates for IRI. These signatures might help to identify potential danger factors and their networks at both the ex situ (ischemic) as well as the reperfusion phase in the recipient after implantation.

The HeartWare Ventricular Assist Device (HVAD): A Single Institutional 10-Year Experience.

OBJECTIVES: The aim of this study was to analyze our 10-year experience with the HVAD in a real-world scenario in a high-volume German heart center. METHODS: We retrospectively analyzed outcomes of adults (≥18 years) with terminal heart failure (HF), who underwent HVAD implantation for durable LVAD therapy in our center between October 2009 and March 2020. Primary and secondary end points were all-cause death after implantation and LVAD-associated complications, respectively. We focused the distinct analyses on risk profiles at the time of implantation and implant strategies, i.e., bridge-to-transplant (BTT) or destination therapy (DT). RESULTS: A total of 510 patients were included, with 229 and 281 individuals in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) level 1 (45%) and 2 to 4, respectively. Median follow-up was 26 months (IQR: 5-54 months). Overall survival at 1, 3, and 5 years after HVAD implantation was 66% (95% CI; 61.7-70%), 49.4% (95% CI; 44.9-53.8%), and 37.4% (95% CI; 32.8-42%), not censored for LVAD exchange, LVAD explantation, or heart transplantation. INTERMACS level 1 and peri-operative temporary right heart assistance were independent risk factors for survival. Survival was best in BTT patients undergoing heart transplantation at any time during follow-up. The INTERMACS level at time of HVAD implantation did not affect survival after heart transplantation. Freedom from the combined end point of any device-associated severe complication and death was 44.5% (95% CI; 40-48.8%) at 1-year after implantation. CONCLUSION: The HVAD is a reliable pump for durable mechanical circulatory support even in high-risk patients. Still, heart transplantation outperforms durable MCS therapy for a superior long-term survival.

On the Hydrogen Oxalate Binding Motifs onto Dinuclear Cu and Ag Metal Phosphine Complexes.

We report the binding geometries of the isomers that are formed when the hydrogen oxalate ((CO2 )2 H=HOx) anion attaches to dinuclear coinage metal phosphine complexes of the form [M1 M2 dcpm2 (HOx)]+ with M=Cu, Ag and dcpm=bis(dicyclohexylphosphino)methane, abbreviated [MM]+ . These structures are established by comparison of isomer-selective experimental vibrational band patterns displayed by the cryogenically cooled and N2 -tagged cations with DFT calculations of the predicted spectra for various local minima. Two isomeric classes are identified that feature either attachment of the carboxylate oxygen atoms to the two metal centers (end-on docking) or attachment of oxygen atoms on different carbon atoms asymmetrically to the metal ions (side-on docking). Within each class, there are additional isomeric variations according to the orientation of the OH group. This behavior indicates that HOx undergoes strong and directional coordination to [CuCu]+ but adopts a more flexible coordination to [AgAg]+ . Infrared spectra of the bare ions, fragmentation thresholds and ion mobility measurements are reported to explore the behaviors of the complexes at ambient temperature.

In vitro thrombogenicity testing of pulsatile mechanical circulatory support systems: Design and proof-of-concept.

Thrombogenic complications are a main issue in mechanical circulatory support (MCS). There is no validated in vitro method available to quantitatively assess the thrombogenic performance of pulsatile MCS devices under realistic hemodynamic conditions. The aim of this study is to propose a method to evaluate the thrombogenic potential of new designs without the use of complex in-vivo trials. This study presents a novel in vitro method for reproducible thrombogenicity testing of pulsatile MCS systems using low molecular weight heparinized porcine blood. Blood parameters are continuously measured with full blood thromboelastometry (ROTEM; EXTEM, FIBTEM and a custom-made analysis HEPNATEM). Thrombus formation is optically observed after four hours of testing. The results of three experiments are presented each with two parallel loops. The area of thrombus formation inside the MCS device was reproducible. The implantation of a filter inside the loop catches embolizing thrombi without a measurable increase of platelet activation, allowing conclusions of the place of origin of thrombi inside the device. EXTEM and FIBTEM parameters such as clotting velocity (α) and maximum clot firmness (MCF) show a total decrease by around 6% with a characteristic kink after 180 minutes. HEPNATEM α and MCF rise within the first 180 minutes indicate a continuously increasing activation level of coagulation. After 180 minutes, the consumption of clotting factors prevails, resulting in a decrease of α and MCF. With the designed mock loop and the presented protocol we are able to identify thrombogenic hot spots inside a pulsatile pump and characterize their thrombogenic potential.

Patients with ventricular assist device and cerebral entrapment-Supporting skullcap reimplantation.

Effects of cranioplasty (CP) and skullcap reimplantation after decompressive craniectomy (DC) for cerebral hemorrhage or malignant brain infarction in patients with left ventricular assist device (LVAD) support as bridge to transplantation has not been surveyed yet. The aim of this study was to evaluate outcome and management after CP when aiming for transplantation. Data were collected from our prospective institutional database including all patients undergoing LVAD implantation between 2010 and 2019. Six patients needed CP procedures and were included. Our analysis focused on postoperative outcome, survival, and facilitation of heart transplantation. Study endpoints included also all-cause mortality. From a total of 1010 LVAD implantations during analysis period in our center, six bridge-to-transplantation LVAD patients [median age at LVAD implantation: 32.5 years (IQR: 24.8-39.5 years); four male, HVAD, n = 3; HM II, n = 1; HM 3, n = 2] underwent CP with imminent entrapment secondary to cerebral hemorrhage or malignant infarction. Primary heart failure etiology was myocarditis (n = 2), dilated (n = 2), or ischemic (n = 2). Median INTERMACS class was 1.5 (IQR; 1.0-2.8). Median time on LVAD support to DC procedure was 33 months (IQR: 16-48 months). The indication for DC was intraparenchymal hemorrhage (n = 4), subdural hematoma (n = 1), and malignant middle cerebral artery infarction (n = 1). After a median time of 4 months (IQR: 3.3-4.0 months, range; 2.0-10 months) post DC procedure, CP was subsequently performed without profound neurologic disabilities in all patients. After median time of 26 months (IQR: 21-42 months) follow-up, three patients successfully received heart transplantation, one patient could undergo LVAD explantation for myocardial recovery, and the remaining two patients are still on the list awaiting heart transplantation. CP procedure with skullcap reimplantation is feasible and can be safely performed in LVAD patients, which subsequently may even be eligible for heart transplantation with beneficial prognosis.

Secondary aortic valve replacement in continuous flow left ventricular assist device therapy.

The purpose of the study was to investigate the outcome of secondary surgical aortic valve replacement (sSAVR) in patients with severe aortic regurgitation (AR) in the context of ventricular assist device (VAD) therapy. From 2009 to 2020, 792 patients underwent cf-LVAD implantation [HVAD (Medtronic, USA), n = 585, and HM 3 (Abbott, USA), n = 207]. All cf-LVAD patients with severe AR requiring secondary AVR were enrolled in this study. A total of six patients (median, 40 years, IQR; 34-61 years, 50% male) underwent secondary surgical aortic valve replacement (sSAVR) after cf-LVAD implantation. Median time of previous LVAD support was 26 months (IQR: 21-29 months). Two patients required additional tricuspid valve repair (TVR) and one patient underwent SAVR after failed TAVR. Four patients needed temporary right ventricular assist device (RVAD) with a median of 30 days (IQR; 29-33 days). Three patients were bridged to urgent heart transplantation due to persevering right heart failure, whereas two destination therapy (DT) candidates survived without any associated complications. An additional DT patient died of pneumonia 1 month after sSAVR. Secondary surgical aortic valve replacement in ongoing LVAD patients is an advanced procedure for a complex cohort. In our series, sSAVR was safely performed and effective, but involved a high-risk for subsequent right heart failure, requiring urgent heart transplantation. In LVAD patients with severe AR requiring treatment where TAVR is not feasible, sSAVR can be evaluated as salvage option for bridge to transplant patients or selected destination therapy candidates.

Identification of characteristics, risk factors, and predictors of recurrent LVAD thrombosis: conditions in HeartWare devices.

BACKGROUND: Redictors of repetitive left-ventricular assist device (LVAD)-thrombosis have not been studied yet. METHODS: We identified predictors of recurrent LVAD thrombosis in HeartWare (HVAD) patients in a long-term study from 2010 until 2020. We included all patients with two or more thrombolysis treatments for repetitive HVAD thrombosis and effectiveness of thrombolytic therapy was defined as freedom from stroke, death, another HVAD thrombosis, or surgical device exchange within 30 days after the event. Study endpoints also include all-cause mortality and heart transplantation. RESULTS: A total of 534 HVAD implantations have been screened, and 73 patients (13.7%) developed first HVAD thrombosis after a median of 10 months (IQR; 6-21 months). 46 of these patients had effective thrombolysis in 71.7% (n = 33/46). After a median of 14 months (IQR 4-32 months) follow-up, 17 patients (51.5%) had developed a second HVAD thrombosis and all were treated with t-PA therapy again, resulting in effectiveness in 76.5% (n = 13/17). The four patients with ineffective t-PA therapy underwent subsequent surgical HVAD exchange. Multiple Cox regression model analysis revealed time interval between HVAD implantation and first thrombosis as an independent risk factor of recurrent thrombosis (HR, 0.93, 95% CI 0.87-0.99, p = 0.031). Kaplan-Meier analysis at 3 year follow-up showed no significant difference in overall survival for recurrent vs non-recurrent thrombosis groups (log-rank test, p = 0.959). CONCLUSION: Recurrent HVAD thrombosis mostly appears within 12 months after first thrombosis. Systemic t-PA therapy for recurrent pump thrombosis seems safe, achieving comparable effectiveness rates to initial t-PA therapy. Survival does not differ between patients with or without recurrent HVAD thrombosis.

Translational control in the tumor microenvironment promotes lung metastasis: Phosphorylation of eIF4E in neutrophils.

The translation of mRNAs into proteins serves as a critical regulatory event in gene expression. In the context of cancer, deregulated translation is a hallmark of transformation, promoting the proliferation, survival, and metastatic capabilities of cancer cells. The best-studied factor involved in the translational control of cancer is the eukaryotic translation initiation factor 4E (eIF4E). We and others have shown that eIF4E availability and phosphorylation promote metastasis in mouse models of breast cancer by selectively augmenting the translation of mRNAs involved in invasion and metastasis. However, the impact of translational control in cell types within the tumor microenvironment (TME) is unknown. Here, we demonstrate that regulatory events affecting translation in cells of the TME impact cancer progression. Mice bearing a mutation in the phosphorylation site of eIF4E (S209A) in cells comprising the TME are resistant to the formation of lung metastases in a syngeneic mammary tumor model. This is associated with reduced survival of prometastatic neutrophils due to decreased expression of the antiapoptotic proteins BCL2 and MCL1. Furthermore, we demonstrate that pharmacological inhibition of eIF4E phosphorylation prevents metastatic progression in vivo, supporting the development of phosphorylation inhibitors for clinical use.

Photoinitiated Charge Transfer in a Triangular Silver(I) Hydride Complex and Its Oxophilicity.

The photoexcitation of a triangular silver(I) hydride complex, [Ag3 (µ3 -H)(µ2 -dcpm)3 ](PF6 )2 ([P](PF6 )2 , dcpm=bis(dicyclohexylphosphino)methane), designed with "UV-silent" bis-phosphine ligands, provokes hydride-to-Ag3 single and double electron transfer. The nature of the electronic transitions has been authenticated by absorption and photodissociation spectroscopy in parallel with high-level quantum-chemical computations utilizing the GW method and Bethe-Salpeter equation (GW-BSE). Specific photofragments of mass-selected [P]2+ ions testify to charge transfer and competing pathways resulting from the unique [Ag3 (µ3 -H)]2+ scaffold. This structural motif of [P](PF6 )2 has been unequivocally verified by 1 H NMR spectroscopy in concert with DFT and X-ray diffraction structural analysis, which revealed short equilateral Ag-Ag distances (dAgAg =3.08 Å) within the range of argentophilic interactions. The reduced radical cation [P]. + exhibits strong oxophilicity, forming [P+O2 ].+ ,which is a model intermediate for silver oxidation catalysis.

Bimetallic d10 -Metal Complexes of a Bipyridine Substituted N-Heterocyclic Carbene.

The hybrid ligand 3-(2,2'-bipyridine-6-ylmethyl)-1-mesityl-1H-imidazolylidene (NHCBipy ) featuring both carbene and N-donor sites, was selectively complexed with various d10 metal cations in order to examine its coordination behavior with regard to homo and heterometallic structures. Respective silver complexes can be obtained by the silver oxide route and are suitable transmetallation reagents for the synthesis of gold(I) compounds. Starting from the mononuclear complexes [(NHCBipy )AuCl], [(NHCBipy )Au(C6 F5 )] and [(NHCBipy )2 Au][ClO4 ], open-chain as well as cyclic heterobimetallic complexes containing Cu+ , Ag+ , Zn2+ , Cd2+ , and Hg2+ were synthesized. Furthermore, the homobimetallic species [(NHCBipy )2 M2 ][ClO4 ]2 (M=Cu, Ag) were obtained. All bimetallic compounds were fully characterized including single-crystal X-ray analysis. Their photoluminescence (PL) properties were investigated in the solid state at temperatures between 15 and 295 K and compared with those of the mononuclear species. There is a clear difference in PL properties between the open chain and the cyclic heterobimetallic complexes. The latter species show different PL properties, depending on the metals involved. In addition, collision-induced dissociation (CID) experiments were performed on electrosprayed cations of the cyclic heterobimetallic compounds, to compare the metal binding at the carbene and N-donor sites.

The psychoactive drug Escitalopram affects swimming behaviour and increases boldness in zebrafish (Danio rerio).

Selective serotonin re-uptake inhibitors are pharmaceuticals used to treat a range of psychological disorders. They are frequently found in surface waters in populated areas. In recent years, they have been shown to affect the behaviour of various aquatic organisms in a way that can have ecological effects. In this study, we exposed zebrafish of both sexes to nominally 0.00, 0.15 and 1.50 µg L-1 Escitalopram in flow-through tanks for three weeks. Subsequently, ten swimming behaviour parameters were quantified using high-resolution video tracking. There were noticeable gender differences in the behaviour responses to Escitalopram. Female fish exposed to 1.50 µg L-1 Escitalopram had a lower maximum swimming velocity, stopped less often and exhibited increased boldness (reduced thigmotaxis) compared to controls. Male fish exposed to 1.50 µg L-1 had a lower maximum swimming velocity compared to control fish. At the end of exposures, both length and weight of the females exposed to 1.50 µg L-1 Escitalopram were significantly less than the group of control fish. In addition, males exposed to 1.50 µg L-1 Escitalopram were significantly shorter than control fish. The behaviour, weight and body length of the fish exposed to nominally 0.15 µg L-1 was not significantly different from control fish in either sex. The results of this study demonstrate that Escitalopram can affect subtle but ecologically important aspects of fish behaviour and lends further credibility to the assumption that Escitalopram is an environmentally active pharmaceutical.

Multimodal Imaging for In Vivo Evaluation of Induced Pluripotent Stem Cells in a Murine Model of Heart Failure.

Myocardial stem cell therapy in heart failure is strongly dependent on successful cellular transfer, engraftment, and survival. Moreover, massive cell loss directly after intramyocardial injection is commonly observed, generating the need for efficient longitudinal monitoring of transplanted cells in order to develop more efficient transplantation techniques. Therefore, the aim of the present study was to assess viability and cardiac retention of induced pluripotent stem cells after intramyocardial delivery using in vivo bioluminescence analysis (BLI) and magnetic resonance imaging (MRI). Murine induced pluripotent stem cells (iPSCs) were transfected for luciferase reporter gene expression and labeled intracellularly with supraparamagnetic iron oxide particles. Consequently, 5 × 105 cells were transplanted intramyocardially following left anterior descending coronary artery ligation in mice. Cardiac iPSCs were detected using BLI and serial T2* sequences by MRI in a 14-day follow-up. Additionally, infarct extension and left ventricular (LV) function were assessed by MRI. Controls received the same surgical procedure without cell injection. MRI sequences showed a strong MRI signal of labeled iPSCs correlating with myocardial late enhancement, demonstrating engraftment in the infarcted area. Mean iPSC volumes were 4.2 ± 0.4 mm3 at Day 0; 3.1 ± 0.4 mm3 at Day 7; and 5.1 ± 0.8 mm3 after 2 weeks. Thoracic BLI radiance decreased directly after injection from 1.0 × 106 ± 4.2 × 104 (p/s/cm2 /sr) to 1.0 × 105 ± 4.9 × 103 (p/s/cm2 /sr) on Day 1. Afterward, BLI radiance increased to 1.1 × 106 ± 4.2 × 104 (p/s/cm2 /sr) 2 weeks after injection. Cardiac graft localization was confirmed by ex vivo BLI analysis and histology. Left ventricular ejection fraction was higher in the iPSC group (30.9 ± 0.9%) compared to infarct controls (24.0 ± 2.1%; P < 0.05). The combination of MRI and BLI assesses stem cell fate in vivo, enabling cardiac graft localization with evaluation of LV function in myocardial infarction.