A tetrahedron from homooxacalix[3]arene, the fifth Platonic polyhedron from calixarenes and uranyl.

A self-assembled tetrahedral cage results from two -symmetry building blocks, namely, homooxacalix[3]arene tricarboxylate and uranyl cation, as demonstrated by X-ray crystallography. In the cage, four metals coordinate at the lower rim with the phenolic and ether oxygen atoms to shape the macrocycle with appropriate dihedral angles for tetrahedron formation, whereas four additional uranyl cations further coordinate at the upper-rim carboxylates to finalize the assembly. Counterions dictate the filling and porosity of the aggregates, whereas potassium induces highly porous structures, and tetrabutylammonium yields compact, densely packed frameworks.

Brucellosis in the Brazilian Pantanal wetland: threat to animal production and wildlife conservation.

This review was performed to gather knowledge about brucellosis in livestock and wildlife in the Brazilian Pantanal, a biome with a huge biodiversity and extensive livestock production. Following the preferred reporting items for narrative review guidelines and using the terms "Brucella" and "Pantanal," we explored the PubMed, SciELO, Jstor, Science Direct, and Scholar Google databases. Information on host species, diagnostic test, number of positive animals, and positivity rates were acquired.

Clonality and Persistence of Multiresistant Methicillin-Resistant Coagulase-Negative Staphylococci Isolated from the Staff of a University Veterinary Hospital.

The aim of this study was to characterize methicillin-resistant coagulase-negative staphylococci (MRCoNS) isolates from the healthy staff of a university veterinary hospital in order to assess their importance as a reservoir of antimicrobial resistance and to determine their population structure and evolution. The study duration was over two years (2020-2021), 94 individuals were analyzed in duplicate, and 78 strains were obtained. The overall prevalence of methicillin-resistant strains detected throughout the study was 61.

Metal Coordination Guided Formation of Discrete Neutral Three-Component Hydrogen-Bonded Architectures.

Interesting molecular architectures were obtained by combining heterodimeric quadruple hydrogen-bonding and neutral metal corner braces. The selection of cyclic and noncyclic aggregates from a random mixture of two-component assemblies has been achieved through metal coordination and careful adjustment of monomer rigidity and dimensions.

Selective Formation of - and -Symmetric Supramolecular Tetrahedral Cages and Helicates in Polar Media Assembled via Cooperative Action of Coordination and Hydrogen Bonds.

We report on the synthesis and self-assembly study of novel supramolecular monomers encompassing quadruple hydrogen-bonding motifs and metal-coordinating 2,2'-bipyridine units. When mixed with metal ions such as Fe or Zn, the tetrahedron cage complexes are formed in quantitative yields and full diastereoselectivity, even in highly polar acetonitrile or methanol solvents. The symmetry of the complexes obtained has been shown to depend critically on the flexibility of the ligand.

Molecular Basis for the Recognition of Higher Fullerenes into Ureidopyrimidinone-Cyclotriveratrylene Self-Assembled Capsules.

Fullerenes C60 , C70 , and C84 may be readily encaged within a hydrogen-bonded dimeric capsule, based on two concave cyclotriveratrylene (CTV) scaffolds, each containing three self-complementary 2-ureido-4-[1H]-pyrimidinone (UPy) subunits. NMR spectroscopy and circular dichroism studies, complemented by dispersion-corrected DFT calculations, are reported with the aim of characterizing such capsule-fullerene complexes both structurally and energetically. Six fullerenes are considered: in agreement with experiments, calculations find that encapsulation is most favorable for C84 (on a par with C90 ), and follows the trend C60 View Article and Find Full Text PDF

FATAL CASE OF STREPTOCOCCUS SUIS INFECTION IN A YOUNG WILD BOAR (SUS SCROFA) FROM SOUTHWESTERN SPAIN.

Streptococcus suis is a recognized pathogen that may cause important diseases in pigs and humans. This microorganism has been repeatedly isolated from wild boar (Sus scrofa). However, its health implications for this wild species are still unknown.

Cellular Antisense Activity of PNA-Oligo(bicycloguanidinium) Conjugates Forming Self-Assembled Nanoaggregates.

A series of peptide nucleic acid-oligo(bicycloguanidinium) (PNA-BGn ) conjugates were synthesized and characterized in terms of cellular antisense activity by using the pLuc750HeLa cell splice correction assay. PNA-BG4 conjugates exhibited low micromolar antisense activity, and their cellular activity required the presence of a hydrophobic silyl terminal protecting group on the oligo(BG) ligand and a minimum of four guanidinium units. Surprisingly, a nonlinear dose-response with an activity threshold around 3-4 μM, indicative of large cooperativity, was observed.

Sequence-selective DNA binding with cell-permeable oligoguanidinium-peptide conjugates.

Conjugation of a short peptide fragment from a bZIP protein to an oligoguanidinium tail results in a DNA-binding miniprotein that selectively interacts with composite sequences containing the peptide-binding site next to an A/T-rich tract. In addition to stabilizing the complex with the target DNA, the oligoguanidinium unit also endows the conjugate with cell internalization properties.

Enhancing molecular recognition in electron donor-acceptor hybrids via cooperativity.

Herein, we report the synthesis of guanidinium bis-porphyrin tweezers 1 and fullerene carboxylate 3, their assembly into a novel supramolecular 1@3 electron donor-acceptor hybrid, and its characterization. In solution, the binding constant affording 1@3 is exceptionally high. 1@3, which features a highly confined topography, builds up from a combination of guanidinium-carboxylate hydrogen bonding and π-π stacking/charge-transfer motifs.

Self-assembled squares and triangles by simultaneous hydrogen bonding and metal coordination.

Through the combination of hydrogen bonding and metal-templated self-assembly, molecular squares and molecular triangles are observed in chloroform solution upon the complexation of hydrogen-bonded dimers of para-pyridyl-substituted 2-ureido-4-[1H]-pyrimidinone (UPy) and an appropriate cis-substituted palladium complex. Molecular modeling studies and NMR analysis confirmed the presence of two distinct structures in solution: the tubular structure of the molecular square and propeller-bowl structure of the molecular triangle.

Dynamic multivalency for carbohydrate-protein recognition through dynamic combinatorial libraries based on Fe(II)-bipyridine complexes.

Molecular recognition: Dynamic combinatorial libraries (DCLs) exploiting multivalency effects and metal coordination have been employed for carbohydrate-protein recognition. The interaction of a three-component DCL based on 2,2'-bipyridine (bipy)-Fe(II) complexes with concanavalin A (ConA; see scheme) results in enhanced binding by multivalent presentation with a bias towards mannose-containing library components.

Anion-responsive diguanidinium-based chiral organogelators.

The chiral bicyclic diguanidinium chloride 1 forms gels in aromatic apolar solvents. The gels were characterized at different levels of organization, from the macroscopic to the molecular level by using microscopy, spectroscopy, and powder X-ray diffraction. The dependency on chirality has been highlighted by circular dichroism and electron microscopy.

Non-peptidic cell-penetrating agents: synthesis of oligomeric chiral bicyclic guanidinium vectors.

Polycationic oligo(chiral bicyclic guanidines) constitute useful non-peptidic penetrating agents for cell uptake and protein surface recognition. We report herein improved and selective procedures for the preparation of oligoguanidinium scaffolds linked through thioether bonds, with similar or different groups and functions at both ends of the chain. Two synthetic strategies were developed to obtain these compounds in relatively good yields from a common thioacetate precursor: generation of a disulfide intermediate or thiolate formation.

Giant regular polyhedra from calixarene carboxylates and uranyl.

Self-assembly of large multi-component systems is a common strategy for the bottom-up construction of discrete, well-defined, nanoscopic-sized cages. Icosahedral or pseudospherical viral capsids, built up from hundreds of identical proteins, constitute typical examples of the complexity attained by biological self-assembly. Chemical versions of the so-called 5 Platonic regular or 13 Archimedean semi-regular polyhedra are usually assembled combining molecular platforms with metals with commensurate coordination spheres.

On the role of flexibility in protein-ligand interactions: the example of p53 tetramerization domain.

The recognition of protein surfaces by designed ligands has become an attractive approach in drug discovery. However, the variable nature and irregular behavior of protein surfaces defy this new area of research. The easy to understand "lock-and-key" model is far from being the ideal paradigm in biomolecular interactions and, hence, any new finding on how proteins and ligands behave in recognition events paves a step of the way.

Hydrogen-bonded cyclic tetramers based on ureidopyrimidinones attached to a 3,6-carbazolyl spacer.

Direct attachment of two 2-ureido-4-[1H]-pyrimidinone (UPy) subunits to a 3,6-carbazolyl core gives rise to a highly viscous, supramolecular polymer. However, insertion of a methylene spacer between the UPy's and the carbazole leads to a well-defined, cyclic tetramer, in a belt-shaped arrangement, as evidenced by MALDI-TOF, DOSY, and NOESY spectra.

A deep tetranuclear metallo-cavitand with bis(aryl) palladium bridges.

A neutral metallo-cavitand based on cis bis-perhaloaryl Pd(II) bridges co-ordinated at the corners of a deep calix[4]arene. Both the metallo-cavitand and its inclusion complexes with other calix[4]arenes were investigated by means of (1)H and (19)F NMR experiments.

Tripodal exTTF-CTV hosts for fullerenes.

A receptor for fullerenes featuring three exTTF units linked to a CTV scaffold is described. The exTTF-CTV host forms remarkably stable complexes with both C(60) (log K(a) = 5.3 +/- 0.

A calixarene dendron with surface congestion at the first generation.

The X-ray structure of a dendrimeric receptor based on calixarenes showed a packed periphery in the first generation. The presence of urea groups as linkers between the calix[4]arene core and the calix[6]arene dendrons makes it a good model as an endo-receptor which is able to coordinate squarate dianions with a high association constant.

Outbreak of ringworm in a traditional Iberian pig farm in Spain.

An outbreak of dermatophytosis caused by Microsporum nanum in a traditional Iberian extensive farm is described. The morbidity was 100% among lactating sows; however, suckling and weaning pigs, as well as boars never developed the lesions seen in the sows. The clinical aspects of porcine ringworm caused by this fungus are discussed and the ecology of the organism is reviewed.

Molecular recognition and self-assembly special feature: Calix[4]arene-based conical-shaped ligands for voltage-dependent potassium channels.

Potassium channels are among the core functional elements of life because they underpin essential cellular functions including excitability, homeostasis, and secretion. We present here a series of multivalent calix[4]arene ligands that bind to the surface of voltage-dependent potassium channels (K(v)1.x) in a reversible manner.

Solid-phase synthesis of chiral bicyclic guanidinium oligomers.

A simple solid-phase synthesis of thioether-linked chiral bicyclic guanidinium oligomers for cell internalization purposes has been developed. The approach is based on a Merrifield-like peptide synthesis on Rinkamide-p-methylbenzhydrylamine resin functionalized with Cys(methoxytrityl). A difunctionalized bicyclic guanidinium synthon, bearing both electrophile (O-mesyl) and protected nucleophile (S-methoxytrityl) group, is repeatedly grafted via a nucleophilic substitution.

Stability and structural recovery of the tetramerization domain of p53-R337H mutant induced by a designed templating ligand.

Protein p53 is a transcription factor crucial for cell cycle and genome integrity. It is able to induce both cell arrest when DNA is damaged and the expression of DNA repair machinery. When the damage is irreversible, it triggers apoptosis.

Binding to protein surfaces by supramolecular multivalent scaffolds.

Multivalency plays a pivotal role in biological recognition, particularly at protein-protein and protein-carbohydrate interaction sites. Scaffolds of diverse structure, flexibility, and valency are gaining increasing biomedical importance in the development of artificial multivalent ligands for these interfaces. Relevant examples range from small C(4) symmetric calix[4]arenes and porphyrin ligands, which may achieve nanomolar affinity for protein surfaces of pharmaceutical interest, to large-sized dendrimers that provide promising adherence-inhibition for toxins and other relevant lectins.