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Lanthanides have unique photoluminescence (PL) emission properties, including very long PL lifetimes. This makes them ideal for biological imaging applications, especially using PL lifetime imaging microscopy (PLIM). PLIM is an inherently multidimensional technique with exceptional advantages for quantitative biological imaging. Unfortunately, due to the required prolonged acquisitions times, photobleaching of lanthanide PL emission currently constitutes one of the main drawbacks of PLIM. In this study, we report a small aqueous‐soluble, lanthanide antenna, 8‐methoxy‐2‐oxo‐1,2,4,5‐tetrahydrocyclopenta[de]quinoline‐3‐phosphonic acid, PAnt, specifically designed to dynamically interact with lanthanide ions, serving as exchangeable dye aimed at mitigating photobleaching in PLIM microscopy in cellulo. Thus, self‐assembled lanthanide complexes that may be photobleached during image acquisition are continuously replenished by intact lanthanide antennas from a large reservoir. Remarkably, our self‐assembled lanthanide complex clearly demonstrated a significant reduction of PL photobleaching when compared to well‐established lanthanide cryptates, used for bioimaging. This concept of exchangeable lanthanide antennas opens new possibilities for quantitative PLIM bioimaging. [ABSTRACT FROM AUTHOR]

The scope and stereoselectivity of the acid-promoted cyclization of new tryptophan-based alpha-amino nitriles derived from either ketones or aldehydes to novel hexahydropyrrolo[1',2',3':1,9a,9]imidazo-[1,2-a]indoles is described. The time and stereoselectivity of the reaction mostly depended on both the steric volume of the substituents at the amino nitrile and its stereochemistry.

Two new families of lanthanide antennas are described. 8-Methoxy-4,5-dihydrocyclopenta[de]quinolin-2(1H)-one phosphonates or carboxylates behave as selective antennas exhibiting Eu3+ luminescence in organic solvents, while quinolin-2(1H)-one analogues selectively sensitize the Tb3+ emission. These emissions are quenched by H2O addition. Based on this behaviour, the new lanthanide antennas can be used as highly sensitive water sensors. [ABSTRACT FROM AUTHOR]

The article discusses a significant advancement in quantitative PLIM bioimaging called PAnt (phosphonic acid antenna). PAnt is a small water-soluble lanthanide antenna that can self-assemble with lanthanide ions, serving as an exchangeable probe to overcome photobleaching in PLIM microscopy in cellulo. This allows for continuous replenishment of lanthanide complexes that may be photobleached during acquisition, resulting in remarkable photostability compared to traditional lanthanide cryptates. The research was conducted by Angel Orte, Juan A. González-Vera, and their team, and the article includes artwork by M. Eugenio Vázquez from the University of Santiago de Compostela. [Extracted from the article]

The article discusses a significant advancement in quantitative PLIM bioimaging called PAnt (phosphonic acid antenna). PAnt is a small water-soluble lanthanide antenna that can self-assemble with lanthanide ions, serving as an exchangeable probe to overcome photobleaching in PLIM microscopy in cellulo. The use of PAnt allows for continuous replenishment of lanthanide complexes that may be photobleached during acquisition, resulting in remarkable photostability compared to traditional lanthanide cryptates. The research was conducted by Angel Orte, Juan A. González-Vera, and their colleagues. [Extracted from the article]

The synthesis of new indole alkaloid analogues through highly stereoselective novel domino cyclative halogenation or prenylation reactions of tryptophan-derived [alpha]-amino nitriles is described.

Research has been conducted on phenylalanine- and tryptophan-derived 5-phenyl-1,4-benzodiazepines. The authors describe the stereocontrolled synthesis of these compounds.

Novel 4,5-quinolimide-based fluorophores are more solvatochromic and red-shifted than known naphthalimide analogues. Conjugation of one of these fluorophores to a peptide derived from CDK5 kinase demonstrated its sensitivity for monitoring the interaction with its regulatory partner p25. Introduction of the quinolimide-labelled peptide into living glioblastoma cells probed the interaction with endogenous p25. [ABSTRACT FROM AUTHOR]

A series of Phe-Gly dipeptide-derived piperazinones containing an aromatic urea moiety and a basic amino acid has been synthesized and evaluated as inhibitors of human platelet aggregation induced by the PAR1 agonist SFLLRN and as cytotoxic agents in human cancer cells. The synthetic strategy involves coupling of a protected basic amino acid benzyl amide to 1,2- and 1,2,4-substituted-piperazinone derivatives, through a carbonylmethyl group at the N1-position, followed by formation of an aromatic urea at the exocyclic moiety linked at the C2 position of the piperazine ring and removal of protecting groups. None of the compounds showed activity in the biological evaluation. [ABSTRACT FROM AUTHOR]

The synthesis of 1,4-unsubstituted piperazin-2-ones by one-pot reductive cyclization of PheΨ[CH(CN)NH]Gly pseudodipeptides is described. Studies on the reactivity of the piperazin-2-one ring showed a higher reactivity at the N4 position than at the N1 position. The stepwise regioselective functionalization of piperazin-2-one derivatives showed great potential for molecular diversity generation. [ABSTRACT FROM AUTHOR]

Background: Extending the therapeutic window of intravenous thrombolysis for acute ischemic stroke beyond the established 4.5-hour limit is of critical importance in order to increase the proportion of thrombolysed stroke patients. In this setting, the capacity of MRI to select acute stroke patients for reperfusion therapies in delayed time windows has been and is being tested in clinical trials. However, whether the more available and cost-effective perfusion computed tomography (PCT) may be useful to select candidates for delayed intravenous thrombolysis remains largely unexplored. We aimed to evaluate the safety and efficacy of PCI-guided intravenous thrombolysis beyond 4.5 h after stroke onset. Methods: We prospectively studied all consecutive acute ischemic stroke patients treated with intravenous tissue plasminogen activator (tPA) in our stroke unit between January 2008 and December 2010. Patients treated within 0-4.5 h were treated according to non-contrast CI (NCCI) criteria. Beyond 4.5 h, patients received intravenous tPA according to PCT criteria, i.e. an infarct core on cerebral blood volume (CBV) maps not exceeding ore third of the middle cerebral artery (MCA) territory and tissue at risk as defined by mean transit time-CBV mismatch greater than 20%. Pre-determined primary endpoints were symptomatic hemorrhagic transformation and favorable long-term outcome, while early neurological improvement and MCA recanalization were considered secondary endpoints. Statistical analysis included bivariate comparisons between the two groups for each endpoint and logistic regression models when significance was found in bivariate analyses. This study was approved by our local ethics committee. Results: A total of 245 patients received intravenous thrombolysis. After the groups were matched by baseline National Institutes of Health Stroke Scale score, 172 patients treated at <4.5 hand 43 patients treated at >4.5 h were finally included. Early and late groups were comparable regarding baseline variables; only cardioembolic etiology was more frequent in the >4.5 h group. Rates of symptomatic hemorrhagic transformation (2.9% in the <4.5 h group vs. 2.3% in the >4.5 h group; p = 1.0) and good long-term outcome (64.5 vs. 60.5%, respectively; p = 0.620) were similar between the groups. However, delayed intravenous thrombolysis was independently associated with a worse early clinical course [odds ratio (OR) 2.07, 95% confidence interval (Cl) 1.04-4.1; p = 0.038] and lower 2-hour MCA recanalization rates (OR 0.4, 95% Cl 0.1 7-0.92; p = 0.03). Conclusion: Primary safety and efficacy endpoints were comparable between the early and delayed thrombolysis groups. The results of our exploratory study may justify a randomized clinical trial to test the safety and efficacy of PCT-guided intravenous thrombolysis in acute ischemic stroke patients presenting beyond 4.5 h from symptom onset. [ABSTRACT FROM AUTHOR]