Effect of Terminal Hydroxy Groups on the Structural Properties of Acyl Thioureas.

The 1-acyl thiourea family [R1C(O)NHC(S)NR2R3] exhibits the flexibility to incorporate a wide variety of substituents into their structure. The structural attributes of these compounds are intricately tied to the type and extent of substitution. In the case of 3-mono-substituted thioureas (R2 = H), the conformational behavior is predominantly shaped by the presence of an intramolecular N-H···O=C hydrogen bond. This study delves into the structural consequences stemming from the inclusion of substituents possessing hydrogen-donor capabilities within four novel 1-acyl-3-mono-substituted thiourea derivatives. A comprehensive suite of analytical techniques, encompassing FTIR, Raman spectroscopy, multinuclear (1H and 13C) NMR spectroscopy, single-crystal X-ray diffraction, and supported by computational methods, notably NBO (Natural Bond Orbital) population analysis, Hirshfeld analysis, and QTAIM (Quantum Theory of Atoms in Molecules), was harnessed to scrutinize and characterize these compounds. In the crystalline state, these compounds exhibit an intricate interplay of intermolecular interactions, prominently featuring an expansive network of hydrogen bonds between the hydroxy (-OH) groups and the carbonyl and thiocarbonyl bonds within the 1-acyl thiourea fragment. Notably, the topological analysis underscores significant distinctions in the properties of the acyl thiourea fragment and the intramolecular >C=O···H-N bond when transitioning from the isolated molecule to the crystalline environment.

Assessing the impact of various tuberculin PPD brands on bovine tuberculosis diagnosis.

Although several brands of tuberculin purified protein derivatives (PPDs) are available for diagnosing bovine tuberculosis (bTB), comparative studies to determine their diagnostic accuracy are infrequent. In Ecuador we compared two different PPD brands for bTB diagnosis using skin testing and measuring skin thickness increase. Additionally, we evaluated four PPD brands, including those used for skin testing, in the Bovine Tuberculosis Interferon Gamma Test (IFN-γ test) measuring IFN-γ induction in whole blood. The study included 17 naturally tuberculosis-infected PPD and IFN-γ test positive bovines. Both the field and laboratory results showed significant differences in classifying the 17 bovines as bTB positive or negative. We hypothesize that several factors, such as the genetic background of the cows, sensitization to environmental mycobacteria, M. bovis strains involved in the bTB infection, and the manufacturing procedures of the PPDs, could have influenced the immune reaction toward the different tuberculin PPD brands. Our study emphasizes the necessity for comparative studies aimed at determining the diagnostic accuracy of PPD brands for bTB diagnosis as well as the development of standardized methods for PPD production and potency determination.

Promising Dual Anticancer and Antimetastatic Action by a Cu(II) Complex Derived from Acylhydrazone on Human Osteosarcoma Models.

Osteosarcoma cancers are becoming more common in children and young adults, and existing treatments have low efficacy and a very high mortality rate, making it pressing to search for new chemotherapies with high efficacy and high selectivity index. Copper complexes have shown promise in the treatment of osteosarcoma. Here, we report the synthesis, characterization, and anticancer activity of [Cu(N-N-Fur)(NO3)(H2O)] complex where N-N-Fur is (E)-N'-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazide. The [Cu(N-N-Fur)(NO3)(H2O)] complex was characterized via X-ray diffraction and electron spin resonance (ESR), displaying a copper center in a nearly squared pyramid environment with the nitrate ligand acting as a fifth ligand in the coordination sphere. We observed that [Cu(N-N-Fur)(NO3)(H2O)] binds to DNA in an intercalative manner. Anticancer activity on the MG-63 cell line was evaluated in osteosarcoma monolayer (IC50 2D: 1.1 ± 0.1 µM) and spheroids (IC50 3D: 16.3 ± 3.1 µM). Selectivity assays using nontumoral fibroblast (L929 cell line) showed that [Cu(N-N-Fur)(NO3)(H2O)] has selectivity index value of 2.3 compared to cis-diamminedichloroplatinum(II) (CDDP) (SI = 0.3). Additionally, flow cytometry studies demonstrated that [Cu(N-N-Fur)(NO3)(H2O)] inhibits cell proliferation and conveys cells to apoptosis. Cell viability studies of MG-63 spheroids (IC50 = 16.3 ± 3.1 µM) showed that its IC50 value is 4 times lower than for CDDP (IC50 = 65 ± 6 µM). Besides, we found that cell death events mainly occurred in the center region of the spheroids, indicating efficient transport to the microtumor. Lastly, the complex showed dose-dependent reductions in spheroid cell migration from 7.5 to 20 µM, indicating both anticancer and antimetastatic effects.

Spin canting and slow magnetic relaxation in mononuclear cobalt(II) sulfadiazine ternary complexes.

Monomeric [Co(SDZ)2phen] (1) and [Co(SDZ)(bq)Cl] (2) complexes (SDZ = sulfadiazine, phen = 1,10-phenanthroline, and bq = 2,2'-biquinoline) have been synthesized and characterized. X-ray diffraction studies indicate that SDZ acts as a bidentate ligand coordinating through the sulfonamide and the pyrimidine N atoms in both compounds. In complex 1, the coordination sphere consists of two SDZ ligands and a bis-chelating phen ligand, giving rise to a CoN6 coordination sphere. On the other hand, 2 has a CoN4Cl core, with two N-atoms from SDZ and two from the bq ligand. Both compounds have been studied by dc and ac magnetometry and shown to display slow magnetic relaxation under an optimum external dc field (1 kOe) at low temperatures. Moreover, compound 2 displays long range magnetic ordering provided by spin-canted antiferromagnetism, which has been characterized by further field-dependent magnetic susceptibility measurements, FC/ZFC curves, hysteresis loops and frequency-independent ac curves. The signs of the calculated D parameters, positive in 1 and negative in 2, have been rationalized according to the two lowest-lying transitions in the orbital energy diagrams derived from ab initio ligand field theory (AILFT). In a subsequent attempt to reveal the possible hidden zero-field SMM behaviour, Ni(II)-based 3 and Co(II)-doped Ni(II)-based (with a Ni : Co ratio of 0.9 : 0.1) heterometallic compound 2Ni were synthesized.

Crystal Structure, Hirshfeld Surface Analysis, and Biological Activities of Schiff-Base Derivatives of 4-Aminoantipyrine.

Eight Schiff bases, synthesized by the reaction of 4-aminoantipyrine with different cinnamaldehydes, were studied in the solid state by using vibrational spectroscopy (IR) and X-ray diffraction techniques. The analysis was extended to the solution phase through ultraviolet-vis, fluorescence spectroscopy, and cyclic voltammetry. Finally, the crystal structures of four compounds (3b, 3d, 3g, and 3h) were determined and studied. In addition to the experimental study, theoretical calculations using the semiempirical method PM6/ZDO were performed to understand better the compound's molecular properties, UV-vis, and infrared spectra. The primary difference is the angular conformation of the terminal phenyl rings around the corresponding linking C-N and C-C σ-bonds. Furthermore, as a result of extended bonding, the > C=N- azomethine group-containing Cpyr-N=(CH)-(CR)=(CH)-Cbz chain (with R=H for 3b, 3d, and 3h, and R=CH3 for 3g) is planar, nearly coplanar, with the mean plane of the pyrazole ring. Hirshfeld surface (HS) analysis was used to investigate the crystal packing and intermolecular interactions, which revealed that intermolecular C-H···O and C-H···N hydrogen bonds, π···π stacking, and C-H···π and C=O···π interactions stabilize the compounds. The energy contributions to the lattice energies of potential hydrogen bonds were primarily dispersive and repulsive. All derivatives were tested in vitro on LPS-stimulated mouse macrophages to assess their ability to suppress the LPS-induced inflammatory responses. Only a slight reduction in the level of NO production was found in activated macrophages treated with 3h. Additionally, the derivatives were tested for antimicrobial activity against several clinical bacteria and fungi strains, including three biofilm-forming microorganisms. Nevertheless, only Schiff base 3f showed interesting antibacterial activities with minimum inhibitory concentration (MIC) values as low as 15.6 µM against Enterobacter gergoviae. On the other hand, Schiff base 3f and, to a lesser extent, 3b and 3h showed antifungal activity against clinical isolates of Candida. The lowest MIC value was for 3f against Candida albicans (15.6 µM). It is interesting to note that the same Schiff bases exhibit the highest activity in both biological evaluations.

The Development of a Multiplex PCR Assay for Fast and Cost-Effective Identification of the Five Most Significant Pathogenic Prototheca Species.

A multiplex PCR system (m-PCR) has been developed to accurately differentiate the five most important pathogenic Prototheca species, including the three species associated with infection in dairy cattle (P. ciferrii, P. blaschkeae, and P. bovis) and the two species associated with human infections (P. wickerhamii and P. cutis). The method is low-cost since it employs a simple "heat-shock" method in a TE buffer for DNA extraction. Furthermore, it requires only primers, a Taq polymerase, an agarose gel, and a molecular weight marker for identification. The method was based on published Prototheca cytochrome B sequences and was evaluated using reference strains from each of the five Prototheca species. The validity of the method was confirmed by identifying 50 strains isolated from milk samples. The specificity was tested in silico and with experimental PCR trials, showing no cross-reactions with other Prototheca species, as well as with bacteria, fungi, cows, algae, animals, or humans. The method could detect mixed infections involving two or three Prototheca species, providing a rapid test that delivers results within three hours.

Tautomerism and Rotamerism of Favipiravir and Halogenated Analogues in Solution and in the Solid State.

Favipiravir is an important selective antiviral against RNA-based viruses, and currently, it is being repurposed as a potential drug for the treatment of COVID-19. This type of chemical system presents different carboxamide-rotameric and hydroxyl-tautomeric states, which could be essential for interpreting its selective antiviral activity. Herein, the tautomeric 3-hydroxypyrazine/3-pyrazinone pair of favipiravir and its 6-substituted analogues, 6-Cl, 6-Br, 6-I, and 6-H, were fully investigated in solution and in the solid state through ultraviolet-visible, 1H nuclear magnetic resonance, infrared spectroscopy, and X-ray diffraction techniques. Also, a study of the gas phase was performed using density functional theory calculations. In general, the keto-enol balance in these 3-hydroxy-2-pyrazinecarboxamides is finely modulated by external and internal electrical variations via changes in solvent polarity or by replacement of substituents at position 6. The enol tautomer was prevalent in an apolar environment, whereas an increase in the level of the keto tautomer was favored by an increase in solvent polarity and, even moreso, with a strong hydrogen-donor solvent. Keto tautomerization was favored either in solution or in the solid state with a decrease in 6-substituent electronegativity as follows: H ≫ I ≈ Br > Cl ≥ F. Specific rotameric states based on carboxamide, "cisoide" and "transoide", were identified for the enol and keto tautomer, respectively; their rotamerism is dependent on the tautomerism and not the aggregation state.

First Case Reports of Nontuberculous Mycobacterial (NTM) Lung Disease in Ecuador: Important Lessons to Learn.

Nontuberculous mycobacteria (NTM) lung infections are often misdiagnosed as tuberculosis, which can lead to ineffective antibiotic treatments. In this report, we present three cases of NTM lung infections in Ecuador that were initially diagnosed and treated as tuberculosis based on the results of sputum smear microscopy. The patients, all male, included two immunocompetent individuals and one HIV-positive subject. Unfortunately, sputum culture was not initiated until late in the course of the disease and the cause of the lung infection, Mycobacterium avium complex (MAC), was only identified after the patients had either passed away or were lost to follow-up. These cases are the first documented cases of NTM lung infections in the English medical literature from Ecuador. We emphasize the importance of accurate diagnosis of NTM infections by culture and identification to species level. Sputum smear staining alone cannot differentiate between mycobacterial species, which can lead to misidentification and ineffective treatments. Additionally, reporting NTM pulmonary disease as a notifiable disease to national TB control programs is recommended to obtain accurate prevalence data. These data are critical in determining the importance of this public health problem and the necessary actions needed to address it.

Multifunctional organometallic compounds for the treatment of Chagas disease: Re(I) tricarbonyl compounds with two different bioactive ligands.

Chagas' disease (American Trypanosomiasis) is an ancient and endemic illness in Latin America caused by the protozoan parasite Trypanosoma cruzi. Although there is an urgent need for more efficient and less toxic chemotherapeutics, no new drugs to treat this disease have entered the clinic in the last decades. Searching for metal-based prospective antichagasic drugs, in this work, multifunctional Re(I) tricarbonyl compounds bearing two different bioactive ligands were designed: a polypyridyl NN derivative of 1,10-phenanthroline and a monodentate azole (Clotrimazole CTZ or Ketoconazol KTZ). Five fac-[Re(CO)3(NN)(CTZ)](PF6) compounds and a fac-[Re(CO)3(NN)(KTZ)](PF6) were synthesized and fully characterized. They showed activity against epimastigotes (IC50 3.48-9.42 µM) and trypomastigotes of T. cruzi (IC50 0.61-2.79 µM) and moderate to good selectivity towards the parasite compared to the VERO mammalian cell model. In order to unravel the mechanism of action of our compounds, two potential targets were experimentally and theoretically studied, namely DNA and one of the enzymes involved in the parasite ergosterol biosynthetic pathway, CYP51 (lanosterol 14-α-demethylase). As hypothesized, the multifunctional compounds shared in vitro a similar mode of action as that disclosed for the single bioactive moieties included in the new chemical entities. Additionally, two relevant physicochemical properties of biological interest in prospective drug development, namely lipophilicity and stability in solution in different media, were determined. The whole set of results demonstrates the potentiality of these Re(I) tricarbonyls as promising candidates for further antitrypanosomal drug development.

High Prevalence of Prototheca bovis Infection in Dairy Cattle with Chronic Mastitis in Ecuador.

The genus Prototheca, a unicellular, non-photosynthetic, yeast-like microalgae, is a pathogen of concern for the dairy industry. It causes bovine mastitis that currently cannot be cured, and hence generates significant economic losses in milk production. In this study, for the first time in Ecuador, we identify Prototheca bovis as the etiologic agent of chronic mastitis in dairy cattle. Milk samples (n = 458) of cows with chronic mastitis were cultured on Sabouraud Dextrose Agar (SDA). Microscopy and cytB gene sequencing were used to identify Prototheca, whereby Prototheca bovis was isolated from 15.1% (n = 69) of the milk samples, one of the highest infection rates that can be found in the literature in a "non-outbreak" situation. No other Prototheca species were found. We were unable to isolate the alga from environmental samples. We showed that P. bovis was relatively resistant to disinfectants used to sterilize milking equipment on the cattle farms where it was isolated. We discuss how to avoid future infection and also hypothesize that the real prevalence of Prototheca infection in bovine mastitis is probably much higher than what was detected. We recommend a protocol to increase the diagnostic yield in the bacteriology laboratory.

The Re-Identification of Previously Unidentifiable Clinical Non-Tuberculous Mycobacterial Isolates Shows Great Species Diversity and the Presence of Other Acid-Fast Genera.

Non-tuberculous mycobacteria that cannot be identified at the species level represent a challenge for clinical laboratories, as proper species assignment is key to implementing successful treatments or epidemiological studies. We re-identified forty-eight isolates of Ziehl-Neelsen (ZN)-staining-positive "acid-fast bacilli" (AFB), which were isolated in a clinical laboratory and previously identified as Mycobacterium species but were unidentifiable at the species level with the hsp65 PCR restriction fragment length polymorphism analysis (PRA). As most isolates also could not be identified confidently via 16S, hsp65, or rpoB DNA sequencing and a nBLAST search analysis, we employed a phylogenetic method for their identification using the sequences of the 16S rDNA, which resulted in the identification of most AFB and a Mycobacterium species diversity not found before in our laboratory. Most were rare species with only a few clinical reports. Moreover, although selected with the ZN staining as AFB, not all isolates belonged to the genus Mycobacterium, and we report for the first time in Latin America the isolation of Nocardia puris, Tsukamurella pulmosis, and Gordonia sputi from sputum samples of symptomatic patients. We conclude that ZN staining does not differentiate between the genus Mycobacterium and other genera of AFB. Moreover, there is a need for a simple and more accurate tree-based identification method for mycobacterial species. For this purpose, and in development in our lab, is a web-based identification system using a phylogenetic analysis (including all AFB genera) based on 16S rDNA sequences (and in the future multigene datasets) and the closest relatives.

Molecular structures of two copper complexes with the pharmaceuticals norfloxacin and tinidazole, when powder X-ray diffraction assists multi-domain single-crystal X-ray diffraction.

The crystal structures of bis[1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-ium-4-yl)-1,4-dihydroquinoline-3-carboxylato]copper(II) sulfate heptahydrate, [Cu(C16H18FN3O3)2]SO4·7H2O or [Cu(nor)2]SO4·7H2O (nor is norfloxacin), and bis{1-[2-(ethylsulfonyl)ethyl]-2-methyl-5-nitroimide}dinitratocopper(II), [Cu(NO3)2(C8H13N3O4S)2] or [Cu(NO3)2(tnz)2] (tnz is tinidazole), were solved by X-ray diffraction. Both complexes crystallize in the space group P21/c, with Z = 4 (for nor) and Z = 2 (for ntz) molecules per unit cell. In [Cu(nor)2]SO4·7H2O, the CuII ion is at the centre of a square-planar environment, trans coordinated to two independent norfloxacin molecules in the zwitterionic form acting as bidentate ligands through one of the carboxyl (cbx) and the carbonyl (cb) O atoms. The solid is further stabilized by an extensive network of N-H...O(sulfate), N-H...O(cbx), N-H...OW, OW-H...O(sulfate) and OW-H...OW hydrogen bonds. The [Cu(NO3)2(tnz)2] complex is centrosymmetric, with the CuII ion in a square planar environment, coordinated to a tinidazole molecule acting as a monodentate ligand through its imidazole N atom and to one nitrate O atom. The vibrational FT-IR absorption spectra and thermal behaviour of the complexes were also studied and are briefly discussed based on the crystal structures.

Synthesis, Experimental and Theoretical Study of Azidochromones.

A series of 2-(haloalkyl)-3-azidomethyl and 6-azido chromones has been synthetized, characterized and studied by theoretical (DFT calculations) and spectroscopic methods (UV-Vis, NMR). The crystal structure of 3-azidomethyl-2-difluoromethyl chromone, determined by X-ray diffraction methods, shows a planar framework due to extended π-bond delocalization. Its molecular packing is stabilized by F···H, N···H and O···H hydrogen bonds, π···π stacking and C-O···π intermolecular interactions. Moreover, AIM, NCI and Hirshfeld analysis evidenced that azido moiety has a significant role in the stabilization of crystal packing through weak intermolecular interactions, where analysis of electronic density suggested closed-shell (CS) interatomic interactions.

Novel 'main-part' isostructuralism in metal complexes with 1-methylimidazole: crystal structures, energy calculations and magnetic properties.

Two new transition metal complexes with 1-methylimidazole (1-MeIm) and azide as ligands, namely, [Co(1-MeIm)4(N3)2] (1) and [Ni(1-MeIm)4(N3)2] (2), have been synthesized and characterized by IR, Raman, UV-Vis and XPS spectroscopy. Their crystal structures were solved by single-crystal X-ray diffraction. The supramolecular self-assembly of the two complexes is governed by non-classical C-H⋯N hydrogen bonds and C-H⋯π interactions. Lattice energies and intermolecular interaction energies for various molecular pairs are quantified using the PIXEL method. DFT computational studies to assess the binding energy through modern tools like non-covalent interaction (NCI plots) analysis and reduced density gradient (RDG) analysis have also been carried out. A detailed analysis of geometric descriptors revealed the existence of quasi-isostructural pairs or 'main-part' isostructuralism in a series formed by 1, 2, and a related cadmium complex, being more evident in the 1/2 pair. DFT studies using theoretical models have been used to disclose the relative importance of the H-bond and C-H⋯π noncovalent interactions. Magnetic measurements for compound 1 show weak ferrimagnetic coupling between adjacent M(II) centers, mediated by H-bonding and C-H⋯π non-covalent interactions.

Photo-Induced Partially Aromatized Intramolecular Charge Transfer.

Diverse models of intramolecular charge transfer (ICT) have been proposed for interpreting the origin of the charge-transfer (CT) state in donor-acceptor (D-A) dyes. However, a large variety of fused-heterocyclic dyes containing a pseudo-aromatic ring in the rigid structure have shown to be incompatible with them. To approximate a solution within the ICT concept, we reported a novel ICT model called partially aromatized intramolecular charge transfer (PAICT). PAICT involves the generation of a CT state from an ICT that occurred within a pre-excited D-A fused-heterocyclic structure possessing a pseudo-aromatic or unstable aromatic ring as the acceptor moiety. The model was proposed from the multiple-emissive mesomeric D-A N1-aryl-2-(trifluoromethyl)benzo[b][1,8]naphthyridin-4(1H)-one, whose excited mesomeric states, which are defined by the aromatic and pseudo-aromatic forms of the pyrindin-4(1H)-one ring, led to a common partial aromatized CT state upon excitation via PAICT. The latter was supported through theoretical calculations on the excited mesomeric states, one-dimensional (1D) and two-dimensional (2D) excitation-emission measurements in different solvents, and the detection of three excited states by lifetime measurements upon 370 nm excitation. The existence of mesomerism was supposed from: (i) two overlapping bands at 370-390 (or 400-420 nm) in UV-vis spectra, (ii) the direct interaction between the pyridinic nitrogen of one molecule and the carbonylic oxygen of the other found in the solid state and, (iii) the detection of three excited states by lifetime measurements. The PAICT opens new perspectives for interpreting the charge-transfer phenomenon in fused-heterocyclic dyes, in particular, those containing a pseudo-aromatic or unstable aromatic ring as an acceptor moiety.

Anticancer activity of a new copper(II) complex with a hydrazone ligand. Structural and spectroscopic characterization, computational simulations and cell mechanistic studies on 2D and 3D breast cancer cell models.

We report here the synthesis, crystal structure, characterization and anticancer activity of a copper(ii)-hydrazone complex, [Cu(MeBHoVa)(H2O)2](NO3) (for short, CuHL), against human breast cancer cells on monolayer (2D) and spheroids/mammospheres (3D). The solid-state molecular structure of the complex has been determined by X-ray diffraction methods. The conformational space was searched and geometries were optimized both in the gas phase and including solvent effects by computational methods based on DFT. The compound has been characterized in the solid state and in solution by spectroscopic (FTIR, Raman, UV-vis) methods. The results were compared with those obtained for the hydrazone ligand and complemented with DFT calculations. Cell viability assays on MCF7 (IC50(CuHL) = 1.7 ± 0.1 µM, IC50(CDDP) = 42.0 ± 3.2 µM) and MDA-MB-231 (IC50(CuHL) = 1.6 ± 0.1 µM, IC50(CDDP) = 131.0 ± 18 µM) demonstrated that the complex displays higher antitumor activity than cisplatin (CDDP) on 2D and 3D human breast cancer cell models. Molecular docking and molecular dynamics simulations showed that CuHL could interacts with DNA, inducing a significant genotoxic effect on both breast cancer cells from 0.5 to 1 µM. On the other hand, CuHL increases the ROS production and induces cell programmed death on breast cancer cells at very low micromolar concentrations (0.5-1.0 µM). Moreover, the compound decreased the amount of breast CSCs on MCF7 and MDA-MB-231 cells reducing the percentage of CD44+/CD24-/low cells from 0.5 to 1.5 µM. In addition, CuHL overcame CDDP with an IC50 value 65-fold lower against breast multicellular spheroids ((IC50(CuHL) = 2.2 ± 0.3 µM, IC50(CDDP) = 125 ± 4.5 µM)). Finally, CuHL reduced mammosphere formation capacity, hence affecting the size and number of mammospheres and showing that the complex exhibits antitumor properties on monolayer (2D) and spheroids (3D) derived from human breast cancer cells.

Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay.

BACKGROUND: Studies of T-cell immune responses against SARS-CoV-2 are important in understanding the immune status of individuals or populations. Here, we use a simple, cheap, and rapid whole blood stimulation assay - an Interferon-Gamma Release Assay (IGRA) - to study T-cell immunity to SARS-CoV-2 in convalescent COVID-19 patients and in unexposed healthy contacts from Quito, Ecuador. METHODS: Interferon-gamma (INF-γ) production was measured in the heparinized blood of convalescent and unexposed subjects after stimulation for 24 h with the SARS-CoV-2 Spike S1 protein, the Receptor Binding Domain (RBD) protein or the Nucleocapsid (NP) protein, respectively. The presence of IgG-RBD protein antibodies in both study groups was determined with an "in-house" ELISA. RESULTS: As measured with INF-γ production, 80% of the convalescent COVID-19 patients, all IgG-RBD seropositive, had a strong T-cell response. However, unexpectedly, 44% of unexposed healthy controls, all IgG-RBD seronegative, had a strong virus-specific T-cell response with the COVID-19 IGRA, probably because of prior exposure to common cold-causing coronaviruses or other viral or microbial antigens. CONCLUSION AND DISCUSSION: The high percentage of unexposed healthy subjects with a pre-existing immunity suggests that a part of the Ecuadorian population is likely to have SARS-CoV-2 reactive T-cells. Given that the IGRA technique is simple and can be easily scaled up for investigations where high numbers of patients are needed, this COVID-19 IGRA may serve to determine if the T-cell only response represents protective immunity to SARS-CoV-2 infection in a population-based study.

Role of hydrogen bonds and weak non-covalent interactions in the supramolecular assembly of 9-hydroxyeucaliptol: crystal structure, Hirshfeld surface analysis, and DFT calculations.

The compound 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-9-ol (9-hydroxyeucaliptol) has been prepared and characterized by single-crystal X-ray diffraction analysis, infrared, Raman, and UV-visible spectroscopies. The molecular geometry of the title compound was also investigated theoretically by density functional theory (DFT) calculations to compare with the experimental data. The substance crystallizes in the trigonal crystal system, space group P32 with Z = 9 molecules per unit cell. There are three independent molecules in the crystal asymmetric unit having the same chirality and showing some differences in the orientation of the H-atom of the hydroxyl group. The crystal structure of 9-hydroxyeucaliptol shows that the hydroxyl group presents an anti-conformation with respect to the O-atom of the ether group. The crystal packing of 9-hydroxyeucaliptol is stabilized by intermolecular O-H···O hydrogen bonds involving the hydroxyl groups of different molecules, which play a decisive role in the preferred conformation adopted in solid state. The intermolecular interactions observed in solid state were also studied through the Hirshfeld surface analysis and quantum theory of atoms in molecules (QTAIM) approaches. Energy framework calculations have also been carried out to analyze and visualize the topology of the supramolecular assembly, and the results indicate a significant contribution from electrostatic energy over the dispersion.

Dental Unit Waterlines in Quito and Caracas Contaminated with Nontuberculous Mycobacteria: A Potential Health Risk in Dental Practice.

Three cases of severe odontogenic infections due to nontuberculous mycobacteria (NTM) in Venezuela that were directly associated with dental procedures and the finding of dental unit waterlines (DUWLs) in dental offices that were colonized with mycobacteria species was the reason for assessing the water quality of DUWLs in dental offices in two capital cities in South America, namely, Quito and Caracas. The main water supplies and the water from 143 DUWLs in both cities were sampled and especially checked for contamination with NTM. To measure the overall bacteriological quality of the water also the presence of heterotrophic bacteria, coliform bacteria, and Pseudomonas was determined. Results showed that respectively 3% and 56% of the DUWLs in Quito and Caracas yielded NTM species (up to 1000 colony-forming units (CFU)/mL). Furthermore, high and unacceptable total viable counts of heterotrophic bacteria and/or coliform bacteria and Pseudomonas were detected in 73% of the samples. We conclude that, in both cities, the water in the majority of DUWLs was contaminated with NTM and other potential pathogens, presenting a risk to human health. The detection of NTM in DUWL water with acceptable heterotrophic bacteria counts shows the need to include NTM in water quality testing. Mycobacteria are more resistant to disinfection procedures than other types of vegetative bacteria, and most testing protocols for DUWLs do not assess mycobacteria and thus do not guarantee risk-free water.