Structure and IR Spectra of 3(5)-Aminopyrazoles and UV-induced tautomerization in argon matrix

The prototropic tautomerism in 3(5)-aminopyrazoles was investigated by matrix isolation infrared (IR) spectroscopy, supported by DFT(B3LYP)/6-311++G(d,p) calculations. In consonance with the experimental data, the calculations predict tautomer 3-aminopyrazole (3AP) to be more stable than the 5-aminopyrazole (5AP) tautomer (calculated energy difference: 10.7 kJ mol−1 ; Gibbs free energy difference: 9.8 kJ mol−1 ). The obtained matrix isolation IR spectra (in both argon and xenon matrices) were interpreted, and the observed bands were assigned to the tautomeric forms with help of vibrational calculations carried out at both harmonic and anharmonic levels. The matrix-isolated compound (in argon matrix) was then subjected to in situ broadband UV irradiation (λ > 235 nm), and the UV-induced transformations were followed by IR spectroscopy. Phototautomerization of the 3AP tautomer into the 5AP form was observed as the strongly prevalent reaction.UI0313B/QUI/2020, UI0313P/QUI/2020info:eu-repo/semantics/publishedVersio

Low temperature matrix-isolation and solid state vibrational spectra of 5-chlorotetrazole

The vibrational spectra of 5-chlorotetrazole (CN4HCl) isolated in an argon matrix (T ¼ 8.5 K) and in the solid state (at room temperature) were studied. The infrared spectrum of monomers of 5-chlorotetrazole isolated in an argon matrix agrees well with the spectrum predicted theoretically (DFT(B3LYP)/6-31G*) for the 2Htautomer of the compound. The bands assigned to the 1H-tautomer appear in the experimental spectrum as very low intensity features. Based on the relative intensities of the bands in the spectra of the 1H- and 2Htautomers, the relative amount of the first tautomer in this matrix can be estimated as 1%. Three matrixes were deposited with different nozzle temperatures and the enthalpy difference between the tautomers DH ¼ 8.0 kJ mol 1 was estimated using the Van’t Hoff relation. The internal energy difference between the two tautomers was predicted theoretically (DFT B3LYP/6-31G*) as 12.6 kJ mol 1. This is in reasonable agreement with experimental observations. In the crystalline phase, this compound exists in its 1H-tautomeric form. Accordingly, the IR spectrum of polycrystalline 5-chlorotetrazole is well reproduced by the spectrum predicted theoretically for the 1H- tautomer

Toxin profile of two Gymnodinium catenatum strains from Iberian Coastal Waters

Gymnodinium catenatum has been the main species responsible for paralytic shellfish poisoning events along the Portuguese coast (Iberian Peninsula), causing bans on bivalve harvesting that result in huge economic losses. This work presents the characterization of two novel isolates of G. catenatum regarding their growth and toxin profiles. Laboratory growth experiments revealed that, although low growth rates were obtained during cultivation, the cell yields were high compared to those reported in the literature. Evaluation of the toxin profiles, by HPLC-FLD, essentially confirmed the typical composition of toxins of this regional population (Iberian Peninsula), namely, the absence or low representation of the toxins dcNEO, GTX1,4 and NEO and a higher ratio of the toxins C1,2, GTX6 and GTX5. However, the percentage of the identified toxins varied among the strains of this study (under the same isolation, growth, and analysis conditions), and also differed from that of other strains described in the literature. Interestingly, we found a comparatively high abundance of dcSTX in both strains, relative to the other toxins, and an unquantifiable amount of C3,4 toxins. In addition to the geographic relationship between toxin profiles, chemical conversions among toxins may explain some differences encountered in the toxin profiles of G. catenatum strains.info:eu-repo/semantics/publishedVersio

Synthesis, structure and antileishmanial evaluation of endoperoxide–pyrazole hybrids

Leishmaniases are among the most impacting neglected tropical diseases. In attempts to repurpose antimalarial drugs or candidates, it was found that selected 1,2,4-trioxanes, 1,2,4,5-tetraoxanes, and pyrazole-containing chemotypes demonstrated activity against Leishmania parasites. This study reports the synthesis and structure of trioxolane–pyrazole (OZ1, OZ2) and tetraoxane–pyrazole (T1, T2) hybrids obtained from the reaction of 3(5)-aminopyrazole with endoperoxide-containing building blocks. Interestingly, only the endocyclic amine of 3(5)-aminopyrazole was found to act as nucleophile for amide coupling. However, the fate of the reaction was influenced by prototropic tautomerism of the pyrazole heterocycle, yielding 3- and 5-aminopyrazole containing hybrids which were characterized by different techniques, including X-ray crystallography. The compounds were evaluated for in vitro antileishmanial activity against promastigotes of L. tropica and L. infantum, and for cytotoxicity against THP-1 cells. Selected compounds were also evaluated against intramacrophage amastigote forms of L. infantum. Trioxolane–pyrazole hybrids OZ1 and OZ2 exhibited some activity against Leishmania promastigotes, while tetraoxane–pyrazole hybrids proved inactive, most likely due to solubility issues. Eight salt forms, specifically tosylate, mesylate, and hydrochloride salts, were then prepared to improve the solubility of the corresponding peroxide hybrids and were uniformly tested. Biological evaluations in promastigotes showed that the compound OZ1•HCl was the most active against both strains of Leishmania. Such finding was corroborated by the results obtained in assessments of the L. infantum amastigote susceptibility. It is noteworthy that the salt forms of the endoperoxide–pyrazole hybrids displayed a broader spectrum of action, showing activity in both strains of Leishmania. Our preliminary biological findings encourage further optimization of peroxide–pyrazole hybrids to identify a promising antileishmanial lead.info:eu-repo/semantics/publishedVersio

Desenvolvimento de metodologias de análise de imagem para quantificar PHA, polifosfatos e glicogénio intracelular em estações de tratamento de águas residuais

O processo de remoção biológica de fósforo, em estações de tratamento de águas residuais, é um processo efetuado por culturas mistas contendo organismos acumuladores de polifosfatos (PAO) e de glicogénio (GAO). No decurso deste processo os microrganismos podem formar inclusões de glicogénio, polihidroxialcanoatos (PHA) e polifosfatos (poli-P). Neste processo, é fulcral monitorizar o metabolismo intracelular para determinar a sua eficiência. Contudo, a sua monitorização, realizada através de análise químicas em diferido, é laboriosa e morosa. Deste modo, existe uma clara necessidade do desenvolvimento de métodos mais expeditos, como metodologias de análise de imagens, para a monitorização destes polímeros intracelulares. Estas técnicas foram implementadas neste estudo, encontrando-se, no caso da determinação da concentração intracelular de poli-P, em fase de desenvolvimento dos protocolos de coloração e aquisição de imagens. Para a determinação da concentração intracelular de glicogénio, foi obtida uma boa correlação inicial. Na determinação da concentração intracelular de PHA, este estudo foca-se na otimização dos protocolos de coloração e no desenvolvimento do programa de análise de imagem

Extracellular electrophysiological measurements of cooperative signals in astrocytes populations

Astrocytes are neuroglial cells that exhibit functional electrical properties sensitive to neuronal activity and capable of modulating neurotransmission. Thus, electrophysiological recordings of astroglial activity are very attractive to study the dynamics of glial signaling. This contribution reports on the use of ultra-sensitive planar electrodes combined with low noise and low frequency amplifiers that enable the detection of extracellular signals produced by primary cultures of astrocytes isolated from mouse cerebral cortex. Recorded activity is characterized by spontaneous bursts comprised of discrete signals with pronounced changes on the signal rate and amplitude. Weak and sporadic signals become synchronized and evolve with time to higher amplitude signals with a quasi-periodic behavior, revealing a cooperative signaling process. The methodology presented herewith enables the study of ionic fluctuations of population of cells, complementing the single cells observation by calcium imaging as well as by patch-clamp techniques.Portuguese Foundation for Science and Technology (FCT) [PTDC/EEI-AUT/5442/2014]; Instituto de Telecomunicacoes [UID/Multi/04326/2013]; Associated Laboratory - Institute of Nanoscience and Nanotechnology [POCI-01-0145-FEDER-016623]; [PTDC/CTM-NAN/3146/2014]info:eu-repo/semantics/publishedVersio

West Nile virus transmission. results from the integrated surveillance system in Italy, 2008 to 2015

IIn Italy a national Plan for the surveillance of imported and autochthonous human vector-borne diseases (chikungunya, dengue, Zika virus disease and West Nile virus (WNV) disease) that integrates human and veterinary (animals and vectors) surveillance, is issued and revised annually according with the observed epidemiological changes. Here we describe results of the WNV integrated veterinary and human surveillance systems in Italy from 2008 to 2015. A real time data exchange protocol is in place between the surveillance systems to rapidly identify occurrence of human and animal cases and to define and update the map of affected areas i.e. provinces during the vector activity period from June to October. WNV continues to cause severe illnesses in Italy during every transmission season, albeit cases are sporadic and the epidemiology varies by virus lineage and geographic area. The integration of surveillance activities and a multidisciplinary approach made it possible and have been fundamental in supporting implementation of and/or strengthening preventive measures aimed at reducing the risk of transmission of WNV trough blood, tissues and organ donation and to implementing further measures for vector control

Evolution shapes the responsiveness of the D-box enhancer element to light and reactive oxygen species in vertebrates

The circadian clock is a highly conserved cell-autonomous mechanism that directs daily rhythms in most aspects of biology. Daily entrainment by environmental signals, notably light, is essential for its function. However, our understanding of the mechanisms and the evolution of photic entrainment remains incomplete. Fish represent attractive models for exploring how light regulates the circadian clock due to the direct light sensitivity of their peripheral clocks. Central to this property is the light induced expression of clock genes that is mediated by D-box enhancer elements. Here, using zebrafish cells, we reveal that the light responsive D-box enhancer serves as a nuclear target for reactive oxygen species (ROS). We demonstrate that exposure to short wavelengths of visible light triggers increases in ROS levels via NADPH oxidase activity. Elevated ROS activates the JNK and p38 MAP kinases and in turn, induces clock gene expression via the D-box. In blind cavefish and mammals, where peripheral clocks are no longer entrained by direct illumination, ROS levels are still increased upon light exposure. However, in these species ROS no longer induces D-box driven clock gene transcription. Thus, during evolution, alterations in ROS-responsive signal transduction pathways underlie fundamental changes in peripheral clock photoentrainment

Beta-lactam-induced immediate hypersensitivity reactions: A genome-wide association study of a deeply phenotyped cohort

Background β-lactam antibiotics are associated with a variety of immune-mediated or hypersensitivity reactions, including immediate (Type I) reactions mediated by antigen-specific IgE. Objective To identify genetic predisposing factors for immediate reactions to β-lactam antibiotics. Methods Patients with a clinical history of immediate hypersensitivity reactions to either penicillins or cephalosporins, which were immunologically confirmed, were recruited from allergy clinics. A genome-wide association study (GWAS) was conducted on 662 patients (the discovery cohort) with a diagnosis of immediate hypersensitivity and the main finding was replicated in a cohort of 98 Spanish cases, recruited using the same diagnostic criteria as the discovery cohort. Results GWAS identified rs71542416 within the Class II HLA region as the top hit (P = 2x10-14); this was in linkage disequilibrium with HLA-DRB1*10:01 (OR = 2.93 P = 5.4x10-7) and HLA-DQA1*01:05 (OR=2.93, P=5.4x10-7). Haplotype analysis identified that HLA-DRB1*10:01 was a risk factor even without the HLA-DQA1*01:05 allele. The association with HLA-DRB1*10:01 was replicated in another cohort, with the meta-analysis of the discovery and replication cohorts showing that HLA-DRB1*10:01 increased the risk of immediate hypersensitivity at a genome-wide level (OR = 2.96 P=4.1x10-9). No association with HLA-DRB1*10:01 was identified in 268 patients with delayed hypersensitivity reactions to β-lactams. Conclusion HLA-DRB1*10:01 predisposed to immediate hypersensitivity reactions to penicillins. Further work to identify other predisposing HLA and non-HLA loci is required. Clinical implications This novel insight into the mechanisms of immediate reactions associated with penicillins may be of use in risk stratifying patients where penicillin cannot be excluded as an etiological agent