Anion binding and transport with meso-alkyl substituted two-armed calix[4]pyrroles bearing urea and hydroxyl groups.

Calix[4]pyrroles bearing hydroxyl (1) or urea (3) groups attached to the meso-positions with propyl linkers were synthesized as cis- and trans-isomers. The anion binding properties of cis-1 and cis-3 were screened with ion-mobility mass spectrometry, where cis-1 formed complexes with Cl-, Br- and H2PO4-, whereas cis-3 formed complexes with most of the investigated anions, including Cl-, Br-, I-, NO3-, ClO4-, OTf-, SCN- and PF6-. The structures of the chloride complexes were further elucidated with density functional theory calculations and a crystal structure obtained for cis-1. In solution, chloride and dihydrogenphosphate anion binding with cis-1 and cis-3 were compared using 1H NMR titrations. To assess the suitability of two-armed calix[4]pyrroles as anion transporters, chloride transport studies of cis-1, cis-3 and trans-3 were performed using large unilamellar vesicles. The results revealed that cis-3 had the highest activity among the investigated calix[4]pyrroles, which was related to the improved affinity and isolation of chloride inside the binding cavity of cis-3 in comparison to cis-1. The results indicate that appending calix[4]pyrroles with two hydrogen bonding arms is a feasible strategy to obtain anion transporters and receptors with high anion affinity.

Electrochemical assessment of a tripodal thiourea-based anion receptor at the liquid|liquid interface.

Thiourea-based receptors for anions have been widely studied due to their ability to transport anions across phospholipid bilayers. The binding affinity of a tripodal thiourea-based receptor for anions was assessed at the aqueous|organic interface using electrochemical measurements. A 1 : 1 stoichiometry was determined for the complexation of most anions, with a higher stoichiometry found in the presence of excess Cl- and Br- anions. High stability constants were estimated for the formation of the complexes at the aqueous|1,2-dichlorobenzene (DCB) interface. When compared with an organic solvent of higher polarity, nitrobenzene (NB), the high stability constants observed in DCB are believed to be due to the less competitive environment of the less polar solvent. Protonation of the receptor at the bridgehead tertiary amine was also inferred from the potential-dependent voltammetric measurements that are not related to anion:receptor complexation. The inherent advantages of the electrochemical method with the use of low polarity solvents are expected to provide new insights into the binding and transport of newly-developed neutral receptors.

Chemically Fueled Communication Along a Scaffolded Nanoscale Array of Squaramides.

Relaying conformational change over several nanometers is central to the function of allosterically regulated proteins. Replicating this mechanism artificially would provide important communication tools, but requires nanometer-sized molecules that reversibly switch between defined shapes in response to signaling molecules. In this work, 1.8 nm long rigid rod oligo(phenylene-ethynylene)s are scaffolds for switchable multi-squaramide hydrogen-bond relays. Each relay can adopt either a parallel or an antiparallel orientation relative to the scaffold; the preferred orientation is dictated by a director group at one end. An amine director responded to proton signals, with acid-base cycles producing multiple reversible changes in relay orientation that were reported by a terminal NH, which is 1.8 nm distant. Moreover, a chemical fuel acted as a dissipative signal. As the fuel was consumed, the relay reverted to its original orientation, illustrating how information from out-of-equilibrium molecular signals can be communicated to a distant site.

Monofunctionalized Fluorinated Bambusurils and Their Conjugates for Anion Transport and Extraction.

Bambusurils are macrocyclic molecules that are known for their high binding affinity and selectivity toward anions. Here, we present the preparation of two bambusurils bearing fluorinated substituents and one carboxylic function. These monofunctionalized bambusurils were conjugated with crown ether and cholesterol units. The resulting conjugates were successfully tested in liquid-liquid extraction of inorganic salts and chloride/bicarbonate transport across lipid bilayers.

Transmembrane Transport of Bicarbonate Unravelled*.

Anion receptors can be used to transport ions across lipid bilayers, which has potential for therapeutic applications. Synthetic bicarbonate transporters are of particular interest, as defects in transmembrane transport of bicarbonate are associated with various diseases. However, no convenient method exists to directly observe bicarbonate transport and study the mechanisms involved. Here, an assay is presented that allows the kinetics of bicarbonate transport into liposomes to be monitored directly and with great sensitivity. The assay utilises an encapsulated europium(III) complex, which exhibits a large increase in emission intensity upon binding bicarbonate. Mechanisms involving CO2 diffusion and the dissipation of a pH gradient are shown to be able to lead to an increase in bicarbonate concentration within liposomes, without transport of the anion occurring at all. By distinguishing these alternative mechanisms from actual bicarbonate transport, this assay will inform the future development of bicarbonate transporters.

Transmembrane Transport of Bicarbonate Unravelled.

Invited for the cover of this issue are Dr. Stephen Butler, Dr. Hennie Valkenier and co-workers at Université Libre de Bruxelles, Loughborough University, Masaryk University, and the University of Bristol. The image depicts the transport of bicarbonate anions versus the spontaneous diffusion of CO2 across the lipid bilayer of a liposome. Read the full text of the article at 10.1002/chem.202100491.

Hydrazones in anion transporters: the detrimental effect of a second binding site.

Synthetic anion transporters can be developed using anion receptors that are able to bind the anion and stabilize it in the lipophilic interior of a bilayer membrane, and they usually contain functional groups with acidic NHs, such as ureas, thioureas and squaramides. To assess the suitability of acylhydrazones as a new functional group for the preparation of anion transporters, we have studied a family of thioureas functionalized with these and related functional groups. 1H NMR titrations and DFT calculations indicate that the thioureas bearing acylhydrazone groups behave as chloride receptors with two separate binding sites, of which the acylhydrazone binds weaker than the thiourea. Chloride transport studies show that the additional binding site has a detrimental effect on thiourea-based transporters, and this phenomenon is also observed for bis(thio)ureas with two separate binding sites. We propose that the presence of a second anion binding unit hinders the transport activity of the thiourea due to additional interactions with the phospholipids of the membrane. In agreement with this hypothesis, extensive molecular dynamics simulations suggest that the molecules will tend to be positioned in the water/lipid interface, driven by the interaction of the NHs of the thiourea and of the acylhydrazone groups with the POPC polar head groups and water molecules. Moreover, the interaction energies show that the poorest transporters have indeed the strongest interactions with the membrane phospholipids, inhibiting chloride transport. This detrimental effect of additional functional groups on transport activity should be considered when designing new ion transporters, unless these groups cooperatively promote anion recognition and transmembrane transport.

Influence of the Insertion Method of Aryl-Extended Calix[4]pyrroles into Liposomal Membranes on Their Properties as Anion Carriers.

We disclose the results of our investigations on the influence that the insertion method of aryl-extended calix[4]pyrrole into liposomal membranes exerts on their properties as anion carriers. We use the standard HPTS assay to assess the transport properties of the carriers. We show that the post-insertion of the carrier, as DMSO solution, assigns better transport activities to the "two-wall" α,α-aryl-extended calix[4]pyrrole 1 compared to the "four-wall" α,α,α,α-counterpart 2. Notably, opposite results were obtained when the carriers were pre-inserted into the liposomal membranes. We assign this difference to an improved incorporation of carrier 2 into the membrane when delivered by the pre-insertion method. On the other hand, carrier 1 shows comparable levels of transport independently of the method used for its incorporation. Thus, an accurate comparison of the chloride transport activities featured by these two carriers demands their pre-incorporation in the liposomal membranes. In contrast, using the lucigenin assay with the pre-insertion method both carriers displayed similar transport efficiencies.

The Role of N-Methyl Squaramides in a Hydrogen-Bonding Strategy to Fold Peptidomimetic Compounds.

Small peptides and peptomimetic compounds are valuable tools to probe and study biological systems. Small synthetic peptide analogues adopt a given secondary structure driven by structural modules that organize the compound architecture. Among them, ß- and α-turn mimetics are widely used. This work reports SQ4 and SQ5 squaramido-based turn modules that combine tertiary and secondary squaramide bonds in their structure to control their conformational properties. The efficacy of this combination has been evaluated to promote folding in peptide-like compounds to obtain parallel and antiparallel-hairpin model compounds in hydrogen-bonding competitive media. Crystallographic structures of model compounds and conformational studies based on NMR spectroscopic analysis of the squaramido-peptides confirm that secondary-tertiary squaramides are more prone to adopt the E,Z-conformation than di-secondary squaramides, and consequently are more suitable to gain conformational control over foldable peptidomimetic compounds.

Random variables with moment-matching staircase density functions.

This paper proposes a family of random variables for uncertainty modeling. The variables of interest have a bounded support set, and prescribed values for the first four moments. We present the feasibility conditions for the existence of any of such variables, and propose a class of variables that conforms to such constraints. This class is called staircase because the density of its members is a piecewise constant function. Convex optimization is used to calculate their distributions according to several optimality criteria, including maximal entropy and maximal log-likelihood. The flexibility and efficiency of staircases enable modeling phenomena having a possibly skewed and/or multimodal response at a low computational cost. Furthermore, we provide a means to account for the uncertainty in the distribution caused by estimating staircases from data. These ideas are illustrated by generating empirical staircase predictor models. We consider the case in which the predictor matches the sample moments exactly (a setting applicable to large datasets), as well as the case in which the predictor accounts for the sampling error in such moments (a setting applicable to sparse datasets). A predictor model for the dynamics of an aeroelastic airfoil subject to flutter instability is used as an example. The resulting predictor not only describes the system's response accurately, but also enables carrying out a risk analysis for safe flight.

Comparative phylogeography of endemic Azorean arthropods.

BACKGROUND: For a remote oceanic archipelago of up to 8 Myr age, the Azores have a comparatively low level of endemism. We present an analysis of phylogeographic patterns of endemic Azorean island arthropods aimed at testing patterns of diversification in relation to the ontogeny of the archipelago, in order to distinguish between alternative models of evolutionary dynamics on islands. We collected individuals of six species (representing Araneae, Hemiptera and Coleoptera) from 16 forest fragments from 7 islands. Using three mtDNA markers, we analysed the distribution of genetic diversity within and between islands, inferred the differentiation time-frames and investigated the inter-island migration routes and colonization patterns. RESULTS: Each species exhibited very low levels of mtDNA divergence, both within and between islands. The two oldest islands were not strongly involved in the diffusion of genetic diversity within the archipelago. The most haplotype-rich islands varied according to species but the younger, central islands contributed the most to haplotype diversity. Colonization events both in concordance with and in contradiction to an inter-island progression rule were inferred, while a non-intuitive pattern of colonization from western to eastern islands was also inferred. CONCLUSIONS: The geological development of the Azores has followed a less tidy progression compared to classic hotspot archipelagos, and this is reflected in our findings. The study species appear to have been differentiating within the Azores for <2 Myr, a fraction of the apparent life span of the archipelago, which may indicate that extinction events linked to active volcanism have played an important role. Assuming that after each extinction event, colonization was initiated from a nearby island hosting derived haplotypes, the apparent age of species diversification in the archipelago would be moved closer to the present after each extinction-recolonization cycle. Exploiting these ideas, we propose a general model for future testing.

[Final results of an initiative aiming to improve the referrals from primary care to a Department of Urology]. / Resultados finales de un programa para la mejora de las derivaciones desde las unidades de atención primaria a un Servicio de Urología.

OBJECTIVES: To test two interventions aiming at improving the compliance of primary health care physicians with an agreed-on protocol of referrals to a urology department. METHODS: Joint formative meetings (every six months) were celebrated throughout a 24-month period. Also a counseling telephone line was implemented. 18.088 referrals were analyzed. The effect of both expositions was tested comparing basal data (T0) with the performance at 6, 12, 18 and 24 months later (T1, T2, T3 and T4, respectively). An additional comparison was conducted to approach the results 1 year after the study ended (T5). RESULTS: 61.7% of the referrals at baseline complied with the protocol. A significant improvement was detected at T1 (compliance 73.4%, RR with respect to T0 1.19, 95% CI 1.14- 1.23). At T2, 73.7% of referrals were adequate (RR with respect to T0 1.19, 95% CI 1.15-1.24). The percent of adequate referrals at T3 remained stable (73.4%, RR with respect to T0 1.18, 95% CI 1.15-1.23). Nevertheless, adequacy of referrals by the end of the second year (T4) significantly decreased (67.3%, RR with respect to T0, 1.09, 95% CI 1.05-1.12). Adequacy at T5 was almost identical to the basal (64.4%, RR with respect to T0, 1.04 95% CI 1.04-1.07). CONCLUSIONS: Learning activities can be effective in improving the quality of referrals from primary care to one urology department. Stopping the activities entails an immediate return to the basal standards.

Standardised inventories of spiders (Arachnida, Araneae) of Macaronesia III: dry habitats of Cabo Verde Archipelago (São Vicente and Santo Antão).

Background: With this publication, we contribute to the knowledge of the arachnofauna of Cabo Verde, focusing specifically on the Islands of Santo Antão and São Vicente. Data were obtained from samples collected as part of the project "Macaronesian Islands as a testing ground to assess biodiversity drivers at multiple scales" (FCT - MACDIV, 2015-2018). This project aimed to identify the factors influencing community assembly in Macaronesian islands. For the Cabo Verde Islands, we focused on dry habitats with the additional aim to revise the aracnofauna of this poorly-known fauna. We applied the COBRA (Conservation Oriented Biodiversity Rapid Assessment) sampling protocol in ten 50 m x 50 m dry shrub plots, with five on each of the two islands, using pitfall traps, sweep-netting and active search. Additional ad-hoc samples were also collected and reported. New information: Our sampling of spiders from Cabo Verde (Santo Antão and São Vicente) yielded a total of 3,368 specimens, of which 1300 (39%) were adults. The samples include 21 families, 87 species, 18 of which are morphospecies awaiting formal identification or description at species level. Species in the families Oxyopidae (2 spp.) and Araneidae (8 spp.) were the most abundant, making up 49% of the specimens. From the 68 named species, 14 are endemic to Cabo Verde, 40 are native non-endemic and 14 are introduced. The colonisation status of Cithaeronreimoseri Platnick, 1991 is unknown. Endemic species accounted for 24% (n = 818) of the specimens and native non-endemic for 63% (n = 2122). A total of 29 species were new records for Cabo Verde, with 15 for Santo Antão, seven for São Vicente and seven for both Islands.

On the endemic spider species of the genus Savigniorrhipis Wunderlich, 1992 (Araneae: Linyphiidae) in the Azores (Portugal), with description of a new species.

Savigniorrhipis topographicus new species is described from the Azores. The synapomorphies of Savigniorrhipis are discussed along with the affinities of the genus within the Savignia-group. Given the extremely restricted and increasingly disturbed habitat, S. topographicus new species should be classified as Critically Endangered and its single forest habitat at Topo (São Jorge Island) should increase its current protection level to a strict nature reserve.

Light-Driven Photoconversion of Squaramides with Implications in Anion Transport.

Simple, clean and fast photoconversion of aniline-derived squaramides was achieved by flashlight illumination. UV irradiation enabled the photochemical squaramide ring-opening to generate 1,2-bisketenes, which DMSO trapped as the nucleophilic oxidant. The only photoproducts isolated were 3,4-arylamino maleic anhydrides, which present conformational preferences very different from those of their parent squaramides. Similar photoconversion was achieved in MeOH. The UV-mediated time-dependent anion transport inhibition was demonstrated, establishing a new approach for modulating the transport abilities of AD-squaramides.

Areolar sebaceous hyperplasia with underlying primary duct carcinoma of the breast in a woman with Donohue syndrome (leprechaunism).

Areolar hyperplasia is only reported when exaggerated, and even so, exaggerated areolar sebaceous hyperplasia is rare. We have recently seen a case of areolar sebaceous hyperplasia in a 32-year-old woman with Donohue syndrome (leprechaunism), who also had an invasive ductal carcinoma in the same breast. The patient showed typical "elfin-like" face with wide nostrils and thick lips, large and low-set ears, and dysplastic nails. The areola showed a yellowish thickened plaque of 5-cm diameter that corresponded to a hyperplasia of the sebaceous glands. Immunohistochemistry for the mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2) was performed on the sebaceous hyperplasia and on the breast carcinoma, and no lack of expression of the markers was evidenced. We have found no other reported case of areolar sebaceous hyperplasia either in cases of breast carcinoma or in cases of leprechaunism.

Quality perception in the outpatient area of an Urology department. Can we improve it?

OBJECTIVES: To test patient's satisfaction after consultation in the outpatient area of the Urology Department in a public hospital using a structured interview. METHODS: We used the Comunidad Autónoma de Madrid (CAM) standard interview form modified to include three questions related to the implementation of a 'one-visit'policy and nurses' empowerment. Patients' opinions were gathered with respect to waiting times in the waiting room, facilities, and staff kindness and professionalism. Sample size was estimated in 386 patients. The effect of every predictive factor on the overall satisfaction was tested using the chi square test. To define the effect of every variable in presence of the rest of covariates a logistic regression model was used. RESULTS: Participation reached 65.5%. Overall, 86.4% of the patients were satisfied. Irrespectively of the professional and personal style, the quality perception was homogeneous (p=ns). Multivariate analysis couldn't disclose any independent predictive variable. Only the perception in the item 'overall time available for the consultation' approached statistical significance (p=0.08), with patients scoring high in this variable getting the highest overall satisfaction scores. CONCLUSIONS: There was no personal or professional style particularly related with patient satisfaction. Nevertheless, there is a slight trend towards a higher satisfaction when patients feel enough time has been spent in their consultation. The new organizational resources (one-visit clinic and nurses' empowerment) are both welcome but are not clearly related to patient satisfaction.

Impact of Radiation Quality on Microdosimetry and Chromosome Aberrations for High-Energy (>250 MeV/n) Ions

Studying energy deposition by space radiation at the cellular scale provides insights on health risks to astronauts. Using the Monte Carlo track structure code RITRACKS, and the chromosome aberrations code RITCARD, we performed a modeling study of single-ion energy deposition spectra and chromosome aberrations for high-energy (>250 MeV/n) ion beams with linear energy transfer (LET) varying from 0.22 to 149.2 keV/µm. The calculations were performed using cells irradiated directly by mono-energetic ion beams, and by poly-energetic beams after particle transport in a digital mouse model, representing the radiation exposure of a cell in a tissue. To discriminate events from ion tracks directly traversing the nucleus, to events from δ-electrons emitted by distant ion tracks, we categorized ion contributions to microdosimetry or chromosome aberrations into direct and indirect contributions, respectively. The ions were either ions of the mono-energetic beam or secondary ions created in the digital mouse due to interaction of the beam with tissues. For microdosimetry, the indirect contribution is largely independent of the beam LET and minimally impacted by the beam interactions in mice. In contrast, the direct contribution is strongly dependent on the beam LET and shows increased probabilities of having low and high-energy deposition events when considering beam transport. Regarding chromosome aberrations, the indirect contribution induces a small number of simple exchanges, and a negligible number of complex exchanges. The direct contribution is responsible for most simple and complex exchanges. The complex exchanges are significantly increased for some low-LET ion beams when considering beam transport.

Transmembrane Transport of Bicarbonate by Anion Receptors.

The development of synthetic anion transporters is motivated by their potential application as treatment for diseases that originate from deficient anion transport by natural proteins. Transport of bicarbonate is important for crucial biological functions such as respiration and digestion. Despite this biological relevance, bicarbonate transport has not been as widely studied as chloride transport. Herein we present an overview of the synthetic receptors that have been studied as bicarbonate transporters, together with the different assays used to perform transport studies in large unilamellar vesicles. We highlight the most active transporters and comment on the nature of the functional groups present in active and inactive compounds. We also address recent mechanistic studies that have revealed different processes that can lead to net transport of bicarbonate, as well as studies reported in cells and tissues, and comment on the key challenges for the further development of bicarbonate transporters.